title: Orion molecular cloud complex

abstract: The Orion molecular cloud complex is a star-forming region with stellar ages ranging up to 12 Myr. Two giant molecular clouds are a part of it, Orion A and Orion B. The stars currently forming within the complex are located within these clouds. A number of other somewhat older stars no longer associated with the molecular gas are also part of the complex, most notably the Orion's Belt, as well as the dispersed population north of it. Near the head of Orion there is also a population of young stars that is centered on Meissa. The complex is between 1 000 and 1 400 light-years away, and hundreds of light-years across. The Orion complex is one of the most active regions of nearby stellar formation visible in the night sky, and is home to both protoplanetary discs and very young stars. Much of it is bright in infrared wavelengths due to the heat-intensive processes involved in stellar formation, though the complex contains dark nebulae, emission nebulae, reflection nebulae, and H II regions. The presence of ripples on the surface of Orion's molecular clouds was discovered in 2010. The ripples are a result of the expansion of the nebulae gas over pre-existing molecular gas. The Orion complex includes a large group of bright nebulae, dark clouds in the Orion constellation. Several nebulae can be observed through binoculars and small telescopes, and some parts are visible to the naked eye.

text:
# Orion molecular cloud complex

The **Orion molecular cloud complex** (or, simply, the **Orion complex**) is a star-forming region with stellar ages ranging up to 12 Myr. Two giant molecular clouds are a part of it, Orion A and Orion B. The stars currently forming within the complex are located within these clouds. A number of other somewhat older stars no longer associated with the molecular gas are also part of the complex, most notably the Orion's Belt (Orion OB1b), as well as the dispersed population north of it (Orion OB1a). Near the head of Orion there is also a population of young stars that is centered on Meissa. The complex is between 1 000 and 1 400 light-years away, and hundreds of light-years across.

The Orion complex is one of the most active regions of nearby stellar formation visible in the night sky, and is home to both protoplanetary discs and very young stars. Much of it is bright in infrared wavelengths due to the heat-intensive processes involved in stellar formation, though the complex contains dark nebulae, emission nebulae, reflection nebulae, and H II regions. The presence of ripples on the surface of Orion's molecular clouds was discovered in 2010. The ripples are a result of the expansion of the nebulae gas over pre-existing molecular gas.

The Orion complex includes a large group of bright nebulae, dark clouds in the Orion constellation. Several nebulae can be observed through binoculars and small telescopes, and some parts (such as the Orion Nebula) are visible to the naked eye.

## Nebulae within the complex

The following is a list of notable regions within the larger complex:

A more complete list can be found for example in Maddalena et al. (1986) Table 1

## Individual components

### Orion A

The giant molecular cloud Orion A is the most active star-forming region in the local neighbourhood of the Sun. In the last few million years about 3000 young stellar objects were formed in this region, including about 190 protostars and about 2600 pre-main sequence stars. The Orion A cloud has a mass in the order of 105 . The stars in Orion A do not have the same distance to us. The "head" of the cloud, which also contains the Orion Nebula is about 1300 light-years (400 parsecs) away from the Sun. The "tail" however is up to 1530 light-years (470 parsecs) away from the Sun. The Orion A cloud is therefore longer than the projected length of 130 light-years (40 parsecs) and has a true length of 290 light-years (90 parsecs).

#### Orion Molecular Clouds

The Orion Molecular Clouds (OMC 1 to OMC 4) are molecular clouds located behind the Orion Nebula. Most of the light from the OMCs are blocked by material from the Orion Nebula, but some features like the Kleinmann-Low Nebula and the Becklin-Neugebauer object can be seen in the infrared. The clouds can be seen in the far-infrared and in radio wavelengths. The Trapezium Cluster has a small angular separation from the Kleinmann-Low Nebula, but the Trapezium Cluster is located inside the Orion Nebula, which is closer towards Earth.

### Orion B

Orion B is about 1370 light-years (420 parsecs) from Earth. It has a size of about 1.5 kpc² and a mass in the order of 105 . It contains several star forming regions with the star cluster inside the Flame Nebula being the largest cluster.

### Orion OB1 association

The Orion OB1 association represents different stellar populations that are superimposed along our line of sight. The oldest group with 8-10 million years is Orion OB1a, northwest of Orion's Belt, and the youngest group with less than 2 million years is Orion OB1d, which contains the Orion Nebula cluster and NGC 2024.

### Lambda Orionis molecular ring

The Lambda Orionis ring is a large molecular ring, centered around Lambda Orioinis (Meissa). It was suggested that this ring formed after a supernova occurred inside the central star-forming region that once surrounded the Lambda Orionis Cluster, dispersing the material into the ring seen today. Star-formation is still continuing in regions of the ring.

### Superbubble

Parts of the Orion-Eridanus superbubble were first seen as Barnard's Loop in Hydrogen-alpha images that warp around the eastern portion of Orion. The other part of the superbubble that is seen in H-alpha is the Eridanus Loop. The walls of the entire bubble are seen in far-infrared and HI. Some features of the Eridanus Loop might be as close as 590 light-years (180 parsecs) to the Sun.

## InfoBox

Orion molecular cloud complex
| Molecular cloud | |
| --- | --- |
| Molecular cloud complex | |
| Part of the Orion molecular cloud complex, with the *Great Nebula in Orion* near the center, along with the *Belt of Orion*, and *Barnard's Loop* curling around the image | |
| Observation data: J2000.0 epoch | |
| Right ascension | 05h 35.3m |
| Declination | −05° 23 |
| Constellation | Orion |
|  | |
| Designations | Orion complex, Orion cloud complex, Orion molecular cloud complex |
|


title: Osbaston, Telford

abstract: Osbaston is a hamlet in the English county of Shropshire. Osbaston forms part of the civil parish of Ercall Magna and the unitary authority of Telford and Wrekin, it lies eleven miles north-west from the centre of Telford.

text:
# Osbaston, Telford

**Osbaston** is a hamlet in the English county of Shropshire.

Osbaston forms part of the civil parish of Ercall Magna and the unitary authority of Telford and Wrekin, it lies eleven miles north-west from the centre of Telford.

Media related to Osbaston, Telford and Wrekin at Wikimedia Commons

## InfoBox

| Osbaston | |
| --- | --- |
| RAF High Ercall, Osbaston | |
| OsbastonLocation within Shropshire | |
| OS grid reference | SJ598187 |
| Civil parish |  |
| Unitary authority |  |
| Ceremonial county |  |
| Region |  |
| Country | England |
| Sovereign state | United Kingdom |
| Post town | TELFORD |
| Postcode district | TF6 |
| Dialling code | 01952 |
|  | |
| Police | West Mercia |
| Fire | Shropshire |
| Ambulance | West Midlands |
|  | |
| UK Parliament |  |
|


title: International Crisis Behavior Project

abstract: The International Crisis Behavior (ICB) Project is a project that collates interstate crisis data from 1918 onward to 2019. The project was created in 1975 by Michael Brecher and Jonathan Wilkenfeld.

text:
# International Crisis Behavior Project

The **International Crisis Behavior** (**ICB**) Project is a project that collates interstate crisis data from 1918 (the end of World War I) onward to 2019. The project was created in 1975 by Michael Brecher and Jonathan Wilkenfeld.

## Data

The International Crisis Behavior project contains data on international crises from 1918 onward (i.e., after the end of World War I). As of March 2023, the newest available data is ICB Version 15. The data for this version extends through 2019 and includes 496 international crises and 1,100 crisis actors. All data is available freely for download.

## Reception

### Academic reception

Data from the ICB has been referenced in a number of academic papers studying the patterns of conflicts and international crises. It was also used in Chapter 3 of the book *What Do We Know About War?* edited by John A. Vasquez. The Forecasting Principles website lists the ICB Project as an important data resource in the analysis of conflict and terror.


title: Orthogonius putzeysi

abstract: Orthogonius putzeysi is a species of ground beetle in the subfamily Orthogoniinae. It was described by Tian & Deuve in 2006.

text:
# Orthogonius putzeysi

***Orthogonius putzeysi*** is a species of ground beetle in the subfamily Orthogoniinae. It was described by Tian & Deuve in 2006.

## InfoBox

| *Orthogonius putzeysi* | |
| --- | --- |
|
| Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Coleoptera |
| Family: | Carabidae |
| Genus: | *Orthogonius* |
| Species: | ***O. putzeysi*** |
| Binomial name | |
| ***Orthogonius putzeysi***<br>Tian & Deuve, 2006 | |
|


abstract: The International Institute of Depth Psychology (IIDP) is a private higher educational establishment in Kyiv, Ukraine. It specializes in psychoanalytic education, including theoretical psychoanalytic education, psychoanalytic training and supervision support for the beginning of practical psychotherapeutic activities. The IIDP was founded in 2001 as the Kyiv branch of the Eastern European Institute of Psychoanalysis, but became independent a year later. In 2002 the International Institute of Depth Psychology obtained its first State License of the Ministry of Education and Science of Ukraine for psychoanalytic programs in education. The institute includes post-graduate psychoanalytic education, the Magistracy of Humanitarian and Social Sciences on Psychology, counseling centers, and a publishing house. The IIDP is a collective member of the Ukrainian Association of Psychoanalysis. In 2011 the Institute was accredited by the European Confederation of Psychoanalytic Psychotherapies. A founder and a rector of the Institute is Svetlana Uvarova.

text:
# International Institute of Depth Psychology

**The International Institute of Depth Psychology** (IIDP) is a private higher educational establishment in Kyiv, Ukraine. It specializes in psychoanalytic education, including theoretical psychoanalytic education, psychoanalytic training (personal analysis) and supervision support for the beginning of practical psychotherapeutic activities.

The IIDP was founded in 2001 as the Kyiv branch of the Eastern European Institute of Psychoanalysis (St. Petersburg), but became independent a year later. In 2002 the International Institute of Depth Psychology obtained its first State License of the Ministry of Education and Science of Ukraine for psychoanalytic programs in education.

The institute includes post-graduate psychoanalytic education, the Magistracy of Humanitarian and Social Sciences on Psychology, counseling centers, and a publishing house. The IIDP is a collective member of the Ukrainian Association of Psychoanalysis.

In 2011 the Institute was accredited by the European Confederation of Psychoanalytic Psychotherapies. A founder and a rector of the Institute is Svetlana Uvarova.

## Programs

The Institute offers a postgraduate course that lasts two and a half years.

The curriculum includes history, theory, methods and techniques of classical psychoanalysis and the main contemporary psychodynamic approaches. Students completing the course earn a National Diploma of Specialist in retraining within specialization in “Practical Psychology (psychoanalysis).”

The institute conducts research on psychoanalytic, psychotherapeutic, socially-psychological and socially-economic problems. The Institute executes consulting, training and supervisory activities. It offers specialized conferences, seminars, round tables, press conferences and tutorial training.

## Departments

### History and Theory of Psychoanalysis

The chairperson of the Department of the History and Theory of Psychoanalysis is Svetlana Bondareva, a psychoanalyst with a master's degree in Clinical Psychology from the University of Nice Sophia Antipolis.

### Clinical Psychoanalysis

The chairperson of the Department of Clinical Psychoanalysis is Inna Karavanova, a psychoanalyst with a master's degree in Psychology from Strasbourg University. She specializes in working with children and adolescents, a chairperson of the section of child psychoanalysis

## Magistracy of Humanitarian and Social Sciences on Psychology

In 2011 a project called Magistracy of Humanitarian and Social Sciences on Psychology was started. The project is a collaboration between the University of Strasbourg, the University of Nice, the IIDP and National Pedagogical Dragomanov University.

A magistracy is a form of training where students engage in psychoanalytic, clinical, scientific and research activities in clinical psychology. It is designed for students who plan to continue their education in doctoral studies or conduct professional activities at a higher level. The program combines aspects of French and Ukrainian approaches in education. The course lasts two years.

The course includes fundamental and theoretical study of psychoanalysis, research activities in the field of practical, social psychology and psychoanalysis.

## Counseling Center

The Counseling Center offers qualified psychoanalysts who assistance to adults, adolescents and children.

### Crisis Center

The center on overcoming crisis is a branch of the Counseling Center. It was established to help people in serious psychological distress. The specialists have completed a specialized program of training in Israel.

## Center for Psychological Expertise

The center is accredited by the Ukrainian Association of Psychoanalysis. The Center carries out psychological research in civil and criminal legal proceedings. The Center also carries out psycho-diagnostics of personality, study of child-parent relations and career counseling.

## Publishing

The literary publishing house *International Institute of Depth Psychology* was founded in 2003. It publishes scientific literature on psychoanalysis, books and periodicals *Psychoanalysis (Chronicle)* and the Russian-language version of the *European Journal of Psychoanalysis.*

## InfoBox

International Institute of Depth Psychology
| Established | 2001 |
| --- | --- |
| Location | Kyiv, Ukraine |


title: Osmium borides

abstract: Osmium borides are compounds of osmium and boron. Their most remarkable property is potentially high hardness. It is thought that a combination of high electron density of osmium with the strength of boron-osmium covalent bonds will make osmium borides superhard materials, however this has not been demonstrated yet. For example, OsB2 is hard (hardness comparable to that of sapphire), but not superhard.

text:
# Osmium borides

**Osmium borides** are compounds of osmium and boron. Their most remarkable property is potentially high hardness. It is thought that a combination of high electron density of osmium with the strength of boron-osmium covalent bonds will make osmium borides superhard materials, however this has not been demonstrated yet. For example, OsB2 is hard (hardness comparable to that of sapphire), but not superhard.

## Synthesis

Osmium borides are produced in vacuum or inert atmosphere to prevent formation of osmium tetroxide, which is a hazardous compound. Synthesis occurs at high temperatures (~1000 °C) from a mixture of MgB2 and OsCl3.

## Structure

Three osmium borides are known: OsB, Os2B3 and OsB2. The first two have hexagonal structure, similar to that of rhenium diboride. Osmium diboride was first also sought as hexagonal, but one of its phases was later reassigned to orthorhombic. In recent methods of synthesis, it has also been found that a hexagonal phase of OsB2 exists with a similar structure to ReB2.


title: International Socialism (magazine)

abstract: International Socialism is a British-based quarterly journal established in 1960 and published in London by the Socialist Workers Party which discusses socialist theory. It is currently edited by Joseph Choonara who replaced Alex Callinicos, who took over for ten years in November 2009 after Chris Harman died. The current journal is the second series following an earlier series which ran from 1960 to 1978 publishing a total of 104 issues. Originally edited by Michael Kidron for its first five years, with Alasdair MacIntyre co-editing it alongside him for 18 months, subsequently the first series was variously edited by Nigel Harris, Chris Harman, Duncan Hallas and Alex Callinicos. The second series was originally edited by Peter Binns, who was succeeded as editor by John Rees. Previously, a single issue of a duplicated journal of this name had been published in 1958 and the first edition of Tony Cliff's essay on Rosa Luxemburg was published, in book form, as issue 2/3 in series with this otherwise one-off publication.

text:
# International Socialism (magazine)

***International Socialism*** is a British-based quarterly journal established in 1960 and published in London by the Socialist Workers Party which discusses socialist theory. It is currently edited by Joseph Choonara who replaced Alex Callinicos, who took over for ten years in November 2009 after Chris Harman died.

The current journal is the second series following an earlier series which ran from 1960 to 1978 publishing a total of 104 issues. Originally edited by Michael Kidron for its first five years, with Alasdair MacIntyre co-editing it alongside him for 18 months, subsequently the first series was variously edited by Nigel Harris, Chris Harman, Duncan Hallas and Alex Callinicos. The second series was originally edited by Peter Binns, who was succeeded as editor by John Rees. Previously, a single issue of a duplicated journal of this name had been published in 1958 and the first edition of Tony Cliff's essay on Rosa Luxemburg was published, in book form, as issue 2/3 in series with this otherwise one-off publication.

## InfoBox

*International Socialism*
| Editor | Joseph Choonara |
| --- | --- |
| Former editors | Michael Kidron, Nigel Harris, Duncan Hallas, Chris Harman, John Rees, Alex Callinicos |
| Categories | Politics |
| Frequency | Quarterly |
| First issue | 1958 (1958) |
| Country | United Kingdom |
| Language | English |
| Website | www.isj.org.uk |
| ISSN | 1754-4653 |


title: Orr Regional Airport

abstract: Orr Regional Airport is a city-owned public-use airport located three nautical miles (6 km) southwest of the central business district of Orr, a city in Saint Louis County, Minnesota, United States. Although most U.S. airports use the same three-letter location identifier for the FAA and IATA, this airport is assigned ORB by the FAA but has no designation from the IATA.

text:
# Orr Regional Airport

**Orr Regional Airport** (ICAO: **KORB**, FAA LID: **ORB**) is a city-owned public-use airport located three nautical miles (6 km) southwest of the central business district of Orr, a city in Saint Louis County, Minnesota, United States.

Although most U.S. airports use the same three-letter location identifier for the FAA and IATA, this airport is assigned **ORB** by the FAA but has no designation from the IATA (which assigned **ORB** to Örebro Airport in Örebro, Sweden).

## Facilities and aircraft

Orr Regional Airport covers an area of 332 acres (134 ha) at an elevation of 1,311 feet (400 m) above mean sea level. It has one runway designated 13/31 with an asphalt surface measuring 4,000 by 75 feet (1,220 x 23 m).

For the 12-month period ending May 31, 2014, the airport had 2,500 general aviation aircraft operations; an average of 208 per month. In March 2017, there were 10 aircraft based at this airport; all 10 single-engine.

## InfoBox

| Orr Regional Airport | |
| --- | --- |
|  | |
| Summary | |
| Airport type | Public |
| Owner | City of Orr |
| Serves | Orr, Minnesota |
| Location | Leiding Township, St. Louis County, Minnesota |
| Elevation AMSL | 1,311 ft / 400 m |
| Coordinates | 48°00′57″N 092°51′22″W / 48.01583°N 92.85611°W / 48.01583; -92.85611 |
| Map | |
| **ORB**Location of airport in Minnesota / United States**ORB****ORB** (the United States) | |
| Runways | |
| Direction Length Surface  ft m  13/31 4,000 1,220 Asphalt | |
| Statistics | |
| Aircraft operations (2014) 2,500  Based aircraft (2017) 10 | |
| Sources: Minnesota DOT, FAA | |


title: Ostedes harmandi

abstract: Ostedes harmandi is a species of beetle in the family Cerambycidae. It was described by Breuning in 1968.

text:
# Ostedes harmandi

***Ostedes harmandi*** is a species of beetle in the family Cerambycidae. It was described by Breuning in 1968.

## InfoBox

| *Ostedes harmandi* | |
| --- | --- |
|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Coleoptera |
| Suborder: | Polyphaga |
| Family: | Cerambycidae |
| Genus: | ***Ostedes*** |
| Species: | ***O. harmandi*** |
| Binomial name | |
| ***Ostedes harmandi***<br>Breuning, 1968 | |
|


title: Oscinisoma

abstract: Oscinisoma is a genus of frit flies in the family Chloropidae. There are about eight described species in Oscinisoma.

text:
# Oscinisoma

***Oscinisoma*** is a genus of frit flies in the family Chloropidae. There are about eight described species in *Oscinisoma*.

## Species

These eight species belong to the genus *Oscinisoma*:

Data sources: i = ITIS, c = Catalogue of Life, g = GBIF, b = Bugguide.net

## Further reading

## InfoBox

| *Oscinisoma* | |
| --- | --- |
|
| Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Diptera |
| Family: | Chloropidae |
| Subfamily: | Oscinellinae |
| Genus: | *Oscinisoma*<br>Lioy, 1864 |
|


title: Oscilloscope types

text:
# Oscilloscope types

This is a subdivision of the Oscilloscope article, discussing the various types and models of oscilloscopes in greater detail.

## Digital oscilloscopes

While analog devices make use of continually varying voltages, digital devices employ binary numbers which correspond to samples of the voltage. In the case of digital oscilloscopes, an analog-to-digital converter (ADC) is used to change the measured voltages into digital information. Waveforms are taken as a series of samples. The samples are stored, accumulating until enough are taken in order to describe the waveform, which are then reassembled for display. Digital technology allows the information to be displayed with brightness, clarity, and stability. There are, however, limitations as with the performance of any oscilloscope. The highest frequency at which the oscilloscope can operate is determined by the analog bandwidth of the front-end components of the instrument and the sampling rate.

Digital oscilloscopes can be classified into two primary categories: digital storage oscilloscopes and digital sampling oscilloscopes. Newer variants include PC-based oscilloscopes (which attach to a PC for data processing and display) and mixed-signal oscilloscopes (which employ other functions in addition to voltage measurement).

### Digital storage oscilloscope

The **digital storage oscilloscope**, or **DSO** for short, is now the preferred type for most industrial applications. Instead of storage-type cathode ray tubes, DSOs use digital memory, which can store data as long as required without degradation. A digital storage oscilloscope also allows complex processing of the signal by high-speed digital signal processing circuits.

The vertical input is digitized by an analog-to-digital converter to create a data set that is stored in the memory of a microprocessor. The data set is processed and then sent to the display, which in early DSOs was a cathode ray tube, but today is an LCD flat panel. DSOs with color LCD displays are common. The sampling data set can be stored to internal or removable storage or sent over a LAN or USB for processing or archiving. A screen image can also be saved to internal or removable storage, or sent to a built-in or externally connected printer, without the need for an oscilloscope camera. The oscilloscope's own signal analysis software can extract many useful time-domain features (e.g., rise time, pulse width, amplitude), frequency spectra, histograms and statistics, persistence maps, and a large number of parameters meaningful to engineers in specialized fields such as telecommunications, disk drive analysis and power electronics..

Digital oscilloscopes are limited principally by the performance of the analog input circuitry, the duration of the sample window, and resolution of the sample rate. When not using equivalent-time sampling, the sampling frequency should be higher than the Nyquist rate which is double the frequency of the highest-frequency component of the observed signal, otherwise aliasing occurs.

Advantages over the analog oscilloscope are:

* Brighter and bigger display with color to distinguish multiple traces
* Simple one-shot acquisitions into memory without the issues that come with storage-type CRTs
* Much more versatile triggers
* No hiding of noise in the phosphor gloom as it happens on analog oscilloscopes
* The input signal is not just converted into a line on the screen, it is available as sample data which can be stored or further processed (i.e. through measurements and analysis tools that come with the oscilloscope)
* Averaging across consecutive samples or scans as well as specific HiRes modes which work through oversampling can lead to higher vertical resolution
* Versatile measurement and analysis functions make it easy to gather all relevant signal properties
* Peak detection to find specific events at long timebase settings on digital oscilloscopes with small memory (less relevant as newer oscilloscopes now come with large memories that keep the sample rate sufficiently high even at very long timebase settings)
* Easy pan and zoom
* Remote control via USB, Ethernet or GPIB

A disadvantage of older digital oscilloscopes is the limited waveform update rate (trigger rate) compared to their analog predecessors, which can make it difficult to spot "glitches" or other rare phenomena with digital oscilloscopes, especially older ones that have no persistence mode. However, thanks to improvements in waveform processing, newer digital oscilloscopes can reach trigger rates in excess of 1 million updates/second, which is more than the roughly 600,000 triggers/sec the best analog oscilloscopes were able to do. Newer digital oscilloscopes also come with analog persistence modes, which replicate the afterglow of an analog oscilloscope's phosphor CRT.

### Digital sampling oscilloscopes

Digital sampling oscilloscopes operate on the same principle as analog sampling oscilloscopes and, like their analog counterparts, are of great use when analyzing high-frequency signals; that is, repetitive signals whose frequencies are higher than the oscilloscope's sampling rate. For measuring repetitive signals, this type once used to offer bandwidth and high-speed timing up to ten times greater than any real-time oscilloscope.

A real-time oscilloscope, which also used to be called a “single-shot” scope, captures an entire waveform on each trigger event. This requires the scope to capture a large number of data points in one continuous record. A sequential equivalent-time sampling oscilloscope, sometimes simply called a “sampling scope,” measures the input signal only once per trigger. The next time the scope is triggered, a small delay is added and another sample is taken. Thus a large number of trigger events must occur in order to collect enough samples to build a picture of the waveform. The measurement bandwidth is determined by the frequency response of the sampler which currently can extend beyond 90 GHz.

An alternative to sequential equivalent-time sampling is called random equivalent-time sampling. Samples are synchronised not with trigger events but with the scope's internal sampling clock. This causes them to occur at apparently random times relative to the trigger event. The scope measures the time interval between the trigger and each sample, and uses this to locate the sample correctly on the x-axis. This process continues until enough samples have been collected to build up a picture of the waveform. The advantage of this technique over sequential equivalent-time sampling is that the scope can collect data from before the trigger event as well as after it, in a similar way to the pre-trigger function of most real-time digital storage scopes. Random equivalent-time sampling can be integrated into a standard DSO without requiring special sampling hardware, but has the disadvantage of poorer timing precision than the sequential sampling method.

However, due to the progress in ADC technology which has led to real-time oscilloscopes with bandwidths over 100 GHz, the demand for digital sampling oscilloscopes has been shrinking, as has the need for integrating equivalent time sampling in real-time oscilloscopes.

### Handheld oscilloscopes

Handheld oscilloscopes are useful for many test and field service applications. Today, a hand-held oscilloscope is usually a real-time oscilloscope, using a monochrome or color LCD display. Typically, a hand-held oscilloscope has one or two analog input channels, but four-input-channel versions are also available. Some instruments combine the functions of a digital multimeter with the oscilloscope. These usually are lightweight and have good accuracy.

### PC-based oscilloscopes

A **PC-based oscilloscope** is a type of digital oscilloscope which relies on a standard PC platform for waveform display and instrument control. In general, there are two types of PC-based oscilloscopes

* Standalone oscilloscopes which contain an internal PC platform (PC mainboard) – common with upper mid-range and high-end oscilloscopes
* External oscilloscopes which connect via USB or Ethernet to a separate PC (desktop or laptop)

At the end of the 1990s, Nicolet and HP introduced the first standalone PC-based oscilloscopes, where the "oscilloscope" part consisted of a specialized signal acquisition system, consisting of an electrical interface providing isolation and automatic gain controls, high-speed analog-to-digital converters, sample memory and on-board Digital Signal Processor (DSPs). The PC part ran Microsoft Windows as the operating system with an oscilloscope application on top, which displayed the waveform data and was used to control the instrument.

Since then, the high-end lines of standalone oscilloscopes of all four major oscilloscope manufacturers (HP/Agilent/Keysight, LeCroy, Tektronix, Rohde & Schwarz) have been based on a PC platform.

The other group of PC-based oscilloscopes are the external oscilloscopes, i.e. where the acquisition system is physically separate from the PC platform. Depending on the exact hardware configuration of the external oscilloscope, the hardware also could be described as a digitizer, a data logger or as a part of a specialized automatic control system. The separate PC provides the display, control interface, disc storage, networking and often the electrical power for the acquisition hardware. The external oscilloscope can transfer data to the computer in two main ways – streaming and block mode. In streaming mode the data is transferred to the PC in a continuous flow without any loss of data. The way in which the PCO is connected to the PC (e.g. Ethernet, USB etc.) will dictate the maximum achievable speed and thereby frequency and resolution using this method. Block mode utilizes the on-board memory of the external oscilloscope to collect a block of data which is then transferred to the PC after the block has been recorded. The acquisition hardware then resets and records another block of data. This process happens very quickly, but the time taken will vary according to the size of the block of data and the speed at which it can be transferred. This method enables a much higher sampling speed, but in many cases the hardware will not record data whilst it is transferring the existing block.

The advantages of a standalone PC-based oscilloscopes include:

* Easy exporting of data to standard PC software such as spreadsheets and word processors which can run on the oscilloscope
* Ability to run analysis tools like numerical analysis software and or signal analysis software directly on the oscilloscope
* Ability to run automation software to perform automatic tests
* Ability to easily control the oscilloscope from a remote location via networking

The advantages of external oscilloscopes are the same as for standalone PC-based oscilloscopes, plus in addition:

* Costs are often lower than for a comparable stand-alone oscilloscope, especially if the user already owns a suitable PC or laptop
* Standalone PCs and laptops typically have large high-resolution color displays which can be easier to read than the smaller displays found on conventional oscilloscopes.
* Portability when used with a laptop PC
* Some external oscilloscopes are much smaller physically than even handheld oscilloscopes

However, PC-based oscilloscopes, standalone or external, also have some disadvantages, which include:

* Power-supply and electromagnetic noise from PC circuits, which requires careful and extensive shielding to obtain good low-level signal resolution
* For external oscilloscopes, the need for the owner to install oscilloscope software on the PC, which may not be compatible with the current release of the PC operating system
* Time for the PC platform to boot, compared with the almost instant start-up of a standalone oscilloscope based on an embedded platform (although every oscilloscope will require a warm-up period to reach specification compliance so this should rarely be an issue)

### Mixed-signal oscilloscopes

A mixed-signal oscilloscope (MSO) combines all the measurement capabilities and the use model of a Digital Storage Oscilloscope with some of the measurement capabilities of a logic analyzer. Analog and digital signals are acquired with a single time base, they are viewed on a single display, and any combination of these signals can be used to trigger the oscilloscope.

MSOs typically lack the advanced digital measurement capabilities and the large number of digital acquisition channels of standalone logic analyzers. Typical mixed-signal measurement uses include the characterization and debugging of hybrid analog/digital circuits like for example embedded systems, Analog-to-digital converters (ADCs), Digital-to-analog converters (DACs), and control systems.

## Cathode-ray oscilloscope

The earliest and simplest type of oscilloscope consisted of a cathode ray tube, a vertical amplifier, a timebase, a horizontal amplifier and a power supply. These are now called "analog" oscilloscopes to distinguish them from the "digital" oscilloscopes that became common in the 1990s and 2000s.

Before the introduction of the CRO in its current form, the cathode ray tube had already been in use as a measuring device. The cathode ray tube is an evacuated glass envelope, similar to that in a black-and-white television set, with its flat face covered in a fluorescent material (the phosphor). The screen is typically less than 20 cm in diameter, much smaller than the one in a television set. Older CROs had round screens or faceplates, while newer CRTs in better CROs have rectangular faceplates.

In the neck of the tube is an electron gun, which is a small heated metal cylinder with a flat end coated with electron-emitting oxides. Close to it is a much-larger-diameter cylinder carrying a disc at its cathode end with a round hole in it; it's called a "grid" (G1), by historic analogy with amplifier vacuum-tube grids. A small negative grid potential (referred to the cathode) is used to block electrons from passing through the hole when the electron beam needs to be turned off, as during sweep retrace or when no trigger events occur.

However, when G1 becomes less negative with respect to the cathode, another cylindrical electrode designated G2, which is hundreds of volts positive referred to the cathode, attracts electrons through the hole. Their trajectories converge as they pass through the hole, creating quite-small diameter "pinch" called the crossover. Following electrodes ("grids"), electrostatic lenses, focus this crossover onto the screen; the spot is an image of the crossover.

Typically, the CRT runs at roughly -2 kV or so, and various methods are used to correspondingly offset the G1 voltage. Proceeding along the electron gun, the beam passes through the imaging lenses and first anode, emerging with an energy in electron-volts equal to that of the cathode. The beam passes through one set of deflection plates , then the other, where it is deflected as required to the phosphor screen.

The average voltage of the deflection plates is relatively close to ground, because they have to be directly connected to the vertical output stage.

By itself, once the beam leaves the deflection region, it can produce a usefully bright trace. However, for higher bandwidth CROs where the trace may move more rapidly across the phosphor screen, a positive post-deflection acceleration ("PDA") voltage of over 10,000 volts is often used, increasing the energy (speed) of the electrons that strike the phosphor. The kinetic energy of the electrons is converted by the phosphor into visible light at the point of impact.

When switched on, a CRT normally displays a single bright dot in the center of the screen, but the dot can be moved about electrostatically or magnetically. The CRT in an oscilloscope always uses electrostatic deflection. Ordinary electrostatic deflection plates can typically move the beam roughly only 15 degrees or so off-axis, which means that oscilloscope CRTs have long, narrow funnels, and for their screen size, are usually quite long. It's the CRT length that makes CROs "deep", from front to back. Modern flat-panel oscilloscopes have no need for such rather-extreme dimensions; their shapes tend to be more like one kind of rectangular lunchbox.

Between the electron gun and the screen are two opposed pairs of metal plates called the deflection plates. The vertical amplifier generates a potential difference across one pair of plates, giving rise to a vertical electric field through which the electron beam passes. When the plate potentials are the same, the beam is not deflected. When the top plate is positive with respect to the bottom plate, the beam is deflected upwards; when the field is reversed, the beam is deflected downwards. The horizontal amplifier does a similar job with the other pair of deflection plates, causing the beam to move left or right. This deflection system is called electrostatic deflection, and is different from the electromagnetic deflection system used in television tubes. In comparison to magnetic deflection, electrostatic deflection can more readily follow random and fast changes in potential, but is limited to small deflection angles.

Common representations of deflection plates are misleading. For one, the plates for one deflection axis are closer to the screen than the plates for the other. Plates that are closer together provide better sensitivity, but they also need to extend far enough along the CRT's axis to obtain adequate sensitivity. (The longer the time a given electron spends in the field, the farther it's deflected.) However, closely spaced long plates would cause the beam to contact them before full amplitude deflection occurs, so the compromise shape has them relatively close together toward the cathode, and flared apart in a shallow vee toward the screen. They are not flat in any but quite-old CRTs!

The timebase is an electronic circuit that generates a ramp voltage. This is a voltage that changes continuously and linearly with time. When it reaches a predefined value the ramp is reset and settles to its starting value. When a trigger event is recognized, provided the reset process (holdoff) is complete, the ramp starts again. The timebase voltage usually drives the horizontal amplifier. Its effect is to sweep the screen end of the electron beam at a constant speed from left to right across the screen, then blank the beam and return its deflection voltages to the left, so to speak, in time to begin the next sweep. Typical sweep circuits can take significant time to reset; in some CROs, fast sweeps required more time to retrace than to sweep.

Meanwhile, the vertical amplifier is driven by an external voltage (the vertical input) that is taken from the circuit or experiment that is being measured. The amplifier has a very high input impedance, typically one megohm, so that it draws only a tiny current from the signal source. Attenuator probes reduce the current drawn even more. The amplifier drives the vertical deflection plates with a voltage that is proportional to the vertical input. Because the electrons have already been accelerated by typically 2kV (roughly), this amplifier also has to deliver almost a hundred volts, and this with a very wide bandwidth. The gain of the vertical amplifier can be adjusted to suit the amplitude of the input voltage. A positive input voltage bends the electron beam upwards, and a negative voltage bends it downwards, so that the vertical deflection at any part of the trace shows the value of the input at that time.

The response of any oscilloscope is much faster than that of mechanical measuring devices such as the multimeter, where the inertia of the pointer (and perhaps damping) slows down its response to the input.

Observing high speed signals, especially non-repetitive signals, with a conventional CRO is difficult, due to non-stable or changing triggering threshold which makes it hard to "freeze" the waveform on the screen. This often requires the room to be darkened or a special viewing hood to be placed over the face of the display tube. To aid in viewing such signals, special oscilloscopes have borrowed from night vision technology, employing a microchannel plate electron multiplier behind the tube face to amplify faint beam currents.

Although a CRO allows one to view a signal, in its basic form it has no means of recording that signal on paper for the purpose of documentation. Therefore, special oscilloscope cameras were developed to photograph the screen directly. Early cameras used roll or plate film, while in the 1970s Polaroid instant cameras became popular. A P11 CRT phosphor (visually blue) was especially effective in exposing film. Cameras (sometimes using single sweeps) were used to capture faint traces.

The power supply is an important component of the oscilloscope. It provides low voltages to power the cathode heater in the tube (isolated for high voltage!), and the vertical and horizontal amplifiers as well as the trigger and sweep circuits. Higher voltages are needed to drive the electrostatic deflection plates, which means that the output stage of the vertical deflection amplifier has to develop large signal swings. These voltages must be very stable, and amplifier gain must be correspondingly stable. Any significant variations will cause errors in the size of the trace, making the oscilloscope inaccurate.

Later analog oscilloscopes added digital processing to the standard design. The same basic architecture — cathode ray tube, vertical and horizontal amplifiers — was retained, but the electron beam was controlled by digital circuitry that could display graphics and text mixed with the analog waveforms. Display time for those was interleaved — multiplexed — with waveform display in basically much the same way that a dual/multitrace oscilloscope displays its channels. The extra features that this system provides include:

* on-screen display of amplifier and timebase settings;
* voltage cursors — adjustable horizontal lines with voltage display;
* time cursors — adjustable vertical lines with time display;
* on-screen menus for trigger settings and other functions.
* automatic measurement of voltage and frequency of a displayed trace

### Dual-beam oscilloscope

A **dual-beam oscilloscope** was a type of oscilloscope once used to compare one signal with another. There were two beams produced in a special type of CRT.

Unlike an ordinary "dual-trace" oscilloscope (which time-shared a single electron beam, thus losing about 50% of each signal), a dual-beam oscilloscope simultaneously produced two separate electron beams, capturing the entirety of both signals. One type (Cossor, UK) had a beam-splitter plate in its CRT, and single-ended vertical deflection following the splitter. (More about this type of oscilloscope appears near the end of this article.)

Other dual-beam oscilloscopes had two complete electron guns, requiring tight control of axial (rotational) mechanical alignment in manufacturing the CRT. In the latter type, two independent pairs of vertical plates deflect the beams. Vertical plates for channel A had no effect on channel B's beam. Similarly for channel B, separate vertical plates existed which deflected the B beam only.

On some dual-beam oscilloscopes the time base, horizontal plates and horizontal amplifier were common to both beams (the beam-splitter CRT worked this way). More elaborate oscilloscopes like the Tektronix 556 and 7844 could employ two independent time bases and two sets of horizontal plates and horizontal amplifiers. Thus one could look at a very fast signal on one beam and a slow signal on another beam.

Most multichannel oscilloscopes do not have multiple electron beams. Instead, they display only one trace at a time, but switch the later stages of the vertical amplifier between one channel and the other either on alternate sweeps (ALT mode) or many times per sweep (CHOP mode). Very few true *dual-beam* oscilloscopes were built.

With the advent of digital signal capture, true dual-beam oscilloscopes became obsolete, as it was then possible to display two truly simultaneous signals from memory using either the ALT or CHOP display technique, or even possibly a raster display mode.

## Analog storage oscilloscope

Trace storage is an extra feature available on some analog oscilloscopes; they used direct-view storage CRTs. Storage allows the trace pattern that normally decays in a fraction of a second to remain on the screen for several minutes or longer. An electrical circuit can then be deliberately activated to store and erase the trace on the screen.

The storage is accomplished using the principle of secondary emission. When the ordinary writing electron beam passes a point on the phosphor surface, not only does it momentarily cause the phosphor to illuminate, but the kinetic energy of the electron beam knocks other electrons loose from the phosphor surface. This can leave a net positive charge. Storage oscilloscopes then provide one or more secondary electron guns (called the "flood guns") that provide a steady flood of low-energy electrons traveling towards the phosphor screen. Flood guns cover the entire screen, ideally uniformly. The electrons from the flood guns are more strongly drawn to the areas of the phosphor screen where the writing gun has left a net positive charge; in this way, the electrons from the flood guns re-illuminate the phosphor in these positively charged areas of the phosphor screen.

If the energy of the flood gun electrons is properly balanced, each impinging flood gun electron knocks out one secondary electron from the phosphor screen, thus preserving the net positive charge in the illuminated areas of the phosphor screen. In this way, the image originally written by the writing gun can be maintained for a long time — many seconds to a few minutes. Eventually, small imbalances in the secondary emission ratio cause the entire screen to "fade positive" (light up) or cause the originally written trace to "fade negative" (extinguish). It is these imbalances that limit the ultimate storage time possible.

Storage oscilloscopes (and large-screen storage CRT displays) of this type, with storage at the phosphor, were made by Tektronix. Other companies, notably Hughes, earlier made storage oscilloscopes with a more-elaborate and costly internal storage structure.

Some oscilloscopes used a strictly binary (on/off) form of storage known as "bistable storage". Others permitted a constant series of short, incomplete erasure cycles which created the impression of a phosphor with "variable persistence". Certain oscilloscopes also allowed the partial or complete shutdown of the flood guns, allowing the preservation (albeit invisibly) of the latent stored image for later viewing. (Fading positive or fading negative only occurs when the flood guns are "on"; with the flood guns off, only leakage of the charges on the phosphor screen degrades the stored image.

## Analog sampling oscilloscope

The principle of sampling was developed during the 1930s in Bell Laboratories by Nyquist, after whom the sampling theorem is named. The first sampling oscilloscope was, however, developed in the late 1950s at the Atomic Energy Research Establishment at Harwell in England by G.B.B. Chaplin, A.R. Owens and A.J. Cole. \["A Sensitive Transistor Oscillograph With DC to 300 Mc/s Response", Proc I.E.E. (London) Vol.106, Part B. Suppl., No. 16, 1959\].

The first sampling oscilloscope was an analog instrument, originally developed as a front-end unit for a conventional oscilloscope. The need for this instrument grew out of the requirement of nuclear scientists at Harwell to capture the waveform of very fast repetitive pulses. The current state-of-the-art oscilloscopes — with bandwidths of typically 20 MHz — were not able to do this and the 300 MHz effective bandwidth of their analog sampling oscilloscope represented a considerable advance.

A short series of these "front-ends" was made at Harwell and found much use, and Chaplin et al. patented the invention. Commercial exploitation of this patent was ultimately done by the Hewlett-Packard Company (later Agilent Technologies).

Sampling oscilloscopes achieve their large bandwidths by not taking the entire signal at a time. Instead, only a sample of the signal is taken. The samples are then assembled to create the waveform. This method can only work for repetitive signals, not transient events. The idea of sampling can be thought of as a stroboscopic technique. When using a strobe light, only pieces of the motion are seen, but when enough of these images are taken, the overall motion can be captured

A large number of instruments used in a variety of technical fields are really oscilloscopes with inputs, calibration, controls, display calibration, etc., specialized and optimized for a particular application. In some cases additional functions such as a signal generator are built into the instrument to facilitate measurements that would otherwise require one or more additional instruments.

The waveform monitor in television broadcast engineering is very close to a standard oscilloscope, but it includes triggering circuits and controls that allow a stable display of a composite video frame, field, or even a selected line out of a field. Robert Hartwig explains the waveform monitor as "providing a graphic display of the black-and-white portion of the picture." The black-and-white portion of the video signal is called the "luminance" due to its fluorescent complexion. The waveform monitor's display of black vs. white levels allows the engineer to troubleshoot the quality of the picture and be certain that it is within the required standards. For convenience, the vertical scale of the waveform monitor is calibrated in IRE units.


title: Intelsat 39

abstract: Intelsat 39, also known as IS-39, is a geostationary communications satellite operated by Intelsat and designed and manufactured by Space Systems/Loral on the SSL 1300 satellite bus. It covers Asia, Africa, Europe, and the Middle East from the 62° East longitude. It has a mixed C-band and Ku-band.

text:
# Intelsat 39

**Intelsat 39**, also known as **IS-39**, is a geostationary communications satellite operated by Intelsat and designed and manufactured by Space Systems/Loral (now subsidiary of Maxar Technologies) on the SSL 1300 satellite bus. It covers Asia, Africa, Europe, and the Middle East from the 62° East longitude. It has a mixed C-band and Ku-band.

## Launch

Intelsat 39 was launched on August 6, 2019, on an Ariane 5 launch vehicle from the Guiana Space Center in Kourou, French Guiana, along with EDRS-C/HYLAS-3. From there, the satellite achieved its geostationary orbit by firing its main engine and was positioned at its position at 62° East, replacing Intelsat 902.

## Specifications

Intelsat announced in May 2016 that they had commissioned the satellite manufacturer Space Systems/Loral to produce a modern communications satellite for their fleet. It has powerful C-band and Ku-band transponders, a projected lifespan of more than 15 years and is powered by two solar panels and batteries. It is also three-axis stabilized and weighs around 6,600 kilograms (14,600 pounds). For propulsion, the satellite has both chemical and electric thrusters, using only electric propulsion for in-orbit attitude control.

## InfoBox

Intelsat 39
| Names | IS-39 |
| --- | --- |
|  | |
| Mission type | Communications |
| Operator | Intelsat |
| COSPAR ID | 2019-049B |
| SATCAT no. | 44476 |
| Website | Intelsat 39 |
| Mission duration | 15 years (planned)
Elapsed: 5 years, 1 month and 24 days |
|  | |
|  | |
| Spacecraft properties | |
| Spacecraft | Intelsat 39 |
| Bus | SSL 1300 |
| Manufacturer | Space Systems/Loral |
| Launch mass | 6,600 kg (14,600 lb) |
|  | |
|  | |
| Start of mission | |
| Launch date | 6 August 2019, 19:30:07 UTC |
| Rocket | Ariane 5 ECA (VA-249) |
| Launch site | Centre Spatial Guyanais, ELA-3 |
| Contractor | Arianespace |
|  | |
|  | |
| Orbital parameters | |
| Reference system | Geocentric orbit |
| Regime | Geostationary orbit |
| Longitude | 62° East |
|  | |
|  | |
| Transponders | |
| Band | 128 transponders:
56 C-band
72 Ku-band |
| Coverage area | Asia, Africa, Europe, and the Middle East |
|  | |
| Intelsat constellation | |


title: Intercooler (band)

abstract: Intercooler is a rock band out of Brisbane, Australia

text:
# Intercooler (band)

**Intercooler** is a rock band out of Brisbane, Australia

## Biography

Intercooler was formed by members of a Sunshine Coast band named Uncle Ecstasy. They have released three full-length albums - *Old School Is The New School* (released 2002, and re-issued, with a different track listing, in 2006), *Forever Or Whatever* (released in 2007), and *Time To Let Go* (released September 2011). Intercooler have also released two EPs - *Goodness of the Girl*, and *Dance of a Thousand Promises* (2004).

Intercooler was formed in 2001 when Damon Cox paired up with already established songwriting trio Phil Ballantyne, Joel Potter and Michael Caso (later replaced by Darek Mudge of Screamfeeder). They all had the same affinity for rock music and so decided to form the band Intercooler as their genre was chosen for them.

After completing their first album, Intercooler toured up and down the east coast of their home country of Australia, playing shows with the likes of The Casanovas, Dallas Crane, Peabody, Grinspoon, The Living End and claiming prime international support slots with Teenage Fanclub, Buzzcocks, J Mascis, Gomez, Maxïmo Park, Preston School of Industry and The Delgados.

Four songs from Intercooler's album *Old School Is The New School* were added to high rotation on national radio network Triple J, including live favourites "Goodness of the Girl" and "Leaflet". Videos were shot for two of the tracks and both enjoyed airplay on ABC's *Fly TV*, *rage* and also Channel \[V\]. Intercooler was responsible for knocking Jennifer Lopez off the pole position on Fly TV's buzz clip of the week, as voted by viewers.

Intercooler continued on to play the Queensland leg of the Big Day Out and Livid music festivals in 2003. Their first U.S. tour commenced in September of the same year. They supported Red Hot Chili Peppers and Queens of the Stone Age at their Washington, D.C. show plus appeared at Wisconsin's renowned Summerjam festival. The tour also included their own club shows in New York City, Chicago, Philadelphia, Atlanta and more.

2004 saw the release of the EP *Dance of a Thousand Promises* which spent 41 weeks in the top 20 of the Australian Independent Charts and had two songs added to high rotation nationally. Videos for "Cream Puff" and "If I Try" both enjoyed airplay on rage, MTV Australia and Channel \[V\].

The video for "Carving Others", from their *Forever Or Whatever* album, was released in February 2007.

Their music video for "You're Not Gonna Hurt Us Again" was a Finalist for 'Best Music Video' at the Australian Effects & Animation Awards. Directed by Michael Ebner the video stars pro skateboarding star, Corbin Harris and screened at Dendy Cinemas, Rage and other music channels.

## Side projects

* Darek Mudge played lead guitar for Screamfeeder, one of Brisbane's longest serving bands, from 2000 - 2003 and intermittently thereafter.
* In 2005 Damon Cox co-founded Mary Trembles with Skritch (guitars and vocals) and Duey Coert (bass).
* Beginning 2007 Damon Cox also comprises An Horse along with Kate Cooper of Iron On.

## Discography

### Albums

### EPs

### Singles

## InfoBox

| Intercooler | |
| --- | --- |
| 2007 performance at the Annandale hotel | |
| Background information | |
| Origin | Brisbane, Queensland, Australia |
| Genres | Rock |
| Years active | 2001–present |
| Labels | Rhythm Ace/MGM Distribution
Plus One/Shock Records
Silent Echo |
|  | |
| Members | Joel Potter
Phil Ballantyne
Damon Cox
Michael Caso
Darek Mudge |
|  | |
| Website | Official website |


abstract: The International Organization of Masters, Mates & Pilots or MM&P is a United States labor union representing licensed mariners. MM&P represents licensed deck officers on U.S.-flag commercial vessels sailing offshore, on the inland waterways and on civilian-crewed ships in the government fleet; state-licensed marine pilots; marine engineers; mariners who work on tug, ferry and harbor tour vessels in New York Harbor and throughout the Northeast; licensed and unlicensed mariners who work on dredges; and maritime industry shore-side clerical and service workers. In addition, it operates two training facilities: the Maritime Institute of Technology & Graduate Studies near Baltimore, Maryland; and the Pacific Maritime Institute, in Seattle, Washington. It operates hiring halls in port cities in the continental United States and Hawaii.

text:
# International Organization of Masters, Mates & Pilots

The **International Organization of Masters, Mates & Pilots** or **MM&P** is a United States labor union representing licensed mariners.

MM&P represents licensed deck officers on U.S.-flag commercial vessels sailing offshore, on the inland waterways and on civilian-crewed ships in the government fleet; state-licensed marine pilots; marine engineers; mariners who work on tug, ferry and harbor tour vessels in New York Harbor and throughout the Northeast; licensed and unlicensed mariners who work on dredges; and maritime industry shore-side clerical and service workers. In addition, it operates two training facilities: the Maritime Institute of Technology & Graduate Studies near Baltimore, Maryland; and the Pacific Maritime Institute, in Seattle, Washington. It operates hiring halls in port cities in the continental United States and Hawaii.

## History

MM&P's historical roots lie in the frustration felt by steamship pilots who were criminalized for marine accidents but had no voice in policy. They organized in New York in 1887, forming the first local of the American Brotherhood of Steamship Pilots. As more locals were founded, shipmasters expressed interest in joining. As a result, in 1891, the fledgling union changed its name to the American Association of Masters and Pilots of Steam Vessels.

### 20th Century

In 1900, it expanded once again to include all deck officers, and changed its name to the American Association of Masters, Mates, and Pilots of Steam Vessels.

On January 9, 1919 MM&P Local, Harbor No. 1 participated in the 1919 New York City Harbor Strike, as one of six unions that made up the Marine Workers Affiliation of the Port of New York, shutting down the port for weeks.

MM&P was active in the 1934 West Coast waterfront strike, joining in along with the Marine Engineers' Beneficial Association (MEBA) on 19 May 1934. Together, in 1937 the two unions became part of the Maritime Federation of the Pacific (MFP). The alliance, however, was short-lived. In July 1938, MM&P withdrew from the MFP, along with the Sailors' Union of the Pacific and the Marine Firemen, Oilers, Watertenders, and Wipers of the Pacific Coast Union.

In 1954, the union added Canadian locals, and changed its name to the International Organization of Masters, Mates & Pilots.

In 1971, by becoming an affiliate of the International Longshoremen's Association, MM&P was able to distance itself from the fight between the American Federation of Labor's (AFL) Seafarers International Union on one side and the Congress of Industrial Organizations's (CIO) National Maritime Union (NMU) on the other. The link has sometimes been tenuous: some 17 years later, when NMU joined MEBA, MM&P very nearly followed suit.

### 21st Century

In 2017, members of the union approved MM&P's affiliation with the Panamanian Union of Captains and Deck Officers (Union de Capitanes y Oficiales de Cubierta-UCOC). UCOC is the exclusive representative for the bargaining unit covering all licensed deck officers of the tugboat fleet, dredges and related vessels operated by the Panama Canal Authority.

In 2020, Masters, Mates & Pilots separated from the ILA and once again became an affiliate of the AFL-CIO.

In 2021, members of Masters, Mates & Pilots approved MM&P's affiliation with the Mexican merchant marine union, Orden Mexicana de Profesionales Marítimos y Portuarios, Similares y Conexos (Orden Maritima).

### Archives

## InfoBox

MM&P
| International Organization of Masters, Mates & Pilots | |
| --- | --- |
|
| Founded | 1880 |
| Headquarters | Linthicum Heights, Maryland |
| Location |  |
| Members | 5,500 (2018) |
| Key people | Donald J. Marcus, President |
| Affiliations | AFL-CIO |
| Website | www.bridgedeck.org |


title: International Origin

abstract: International Origin was an annual series of rugby league football matches between England and the Exiles. The International Origin was created by the Rugby Football League (RFL) to ensure that the English national side had a good strong mid-season international very much like Australia has with their State of Origin series. The RFL intended this to be an annual one-off game and it was in 2011, however this progressed to a two-game series in 2012. Plans were in the works to make this into a three-game series for the future, however it was scaled back to a standalone fixture in 2013 due to a lack of interest from both players and spectators.

text:
# International Origin

**International Origin** was an annual series of rugby league football matches between England and the Exiles. The International Origin was created by the Rugby Football League (RFL) to ensure that the English national side had a good strong mid-season international very much like Australia has with their State of Origin series. The RFL intended this to be an annual one-off game and it was in 2011, however this progressed to a two-game series in 2012. Plans were in the works to make this into a three-game series for the future, however it was scaled back to a standalone fixture in 2013 due to a lack of interest from both players and spectators.

## Teams

In late 2010 the RFL called for a strong mid-season international for 2011 to try to give England a good competitive fixture before they played the international games at the end of the season.

The England team is selected by the best English players currently playing in the domestic competition (Super League). The Australian-based England players are not released by their clubs as this series is technically not an international test.

The Exiles team is selected from the overseas players in the Super League competition. These players are chosen to form a 23-man squad by a foreign coach (usually an Australian or New Zealand coach). For the Exiles team the fans get to choose who plays for the Exiles. All players in the squad are NRL club trained players. For the 2011 series, the players were chosen by a fan poll.

## History

### Background

The RFL had previously attempted a mid-season series in 2001, reviving the War of the Roses match from the defunct County Championship competition (1895–1983) between Lancashire and Yorkshire under the name "County of Origin Series", inspired by the success of State of Origin series, however this folded in 2003.

### Build Up to the First Origin Game

In 2011 the RFL decided to take the first steps into making the International Origin a success, they had a marketing team put together a couple of screen shots of a hooded figure with the Exiles logo on the front of the hooded garment, this created interest in the rugby league community as these were present at quite a few Super League games in 2011. In addition to this the hooded figures were also seen on every video ref decision with captions such as "They are coming…." accompanied by the Exiles logo, then "…….We are waiting". accompanied by the England logo.

The RFL announced that the first ever Exiles coach would be former Leeds Rhinos coach Brian McLennan, McLennan won numerous accolades with the Leeds Rhinos and his first step as coach of the Exiles was to appoint Leeds Rhinos hooker Danny Buderus as the captain of the Exiles. He therefore became the first ever Exiles player and captain.

### 2011

On 10 June 2011, England took to the field against the Exiles at Leeds Rhinos home ground of Headingley, Leeds. Hull F.C.'s powerful second-rower Willie Manu provided the first try for the Exiles after Wigan Warriors Thomas Leuluai carved up the English defence and offloaded the ball. Winger Pat Richards provided the conversion. England soon hit back with prop James Graham making a half break before offloading the ball to Warrington Wolves scrum half Richie Myler to sprint 35 metres to score, Kevin Sinfield added the extras. The Exiles were to strike next on the scoreboard though, some neat interplay from Rangi Chase, George Carmont and Glenn Morrison saw the Exiles go 55 metres in one play down the left before Leuluai found Brett Hodgson in the centre of the field who provided a nice cross field kick into the arms of Tony Puletua who simple tapped it infield to St Helens R.F.C. teammate Francis Meli who had the easiest of scores. However, with 10 minutes to go Wigan Warriors second-rower Joel Tomkins intercepted a pass on his own 10-metre line and raced nearly the length of the field to score a try, Sinfield once again added the extras to put England into a 12–10 lead. But with a minute left on the clock, Chase offloaded a ball to Puletua who gave a pass to Carmont, Carmont then stepped inside to score the decisive try, Richards converted to give the Exiles their first International Origin win. Exiles stand-off Castleford Tigers Rangi Chase was the Man of the Match.

### 2012

After the mild success of the first International Origin, the RFL decided to use it as an annual series, however they announced that the 2012 series would consist of two games instead of one. The two games would be the start of an ongoing development of the series. The first game was announced to be at St Helens R.F.C.'s new ground Langtree Park whilst the second game was announced as being at Huddersfield Giants Galpharm Stadium. Game 1 of the 2012 series was won by England 18–10, tries from Wigan Warriors back rower Gareth Hock and Hull FC's back rower Danny Tickle ensured England had an early advantage. The Exiles did hit back though through a try shortly before half time from winger Francis Meli. However England remained dominant after the break and a try from Sam Tomkins sealed the win as Kevin Sinfield kicked all 3 goals, the Exiles were able to conjure up a consolation try through Daryl Millard and a Scott Dureau conversion before the end. England's James Roby was the Man of the Match for Game 1.

### 2013

In 2013, the International Origin returned to its one-game format. England would play the Exiles in a one-off Test match at Warrington Wolves home ground Halliwell Jones Stadium on 14 June 2013. England won the match 30–10.

## Results

| Year | Date | Winner | Score | Runner-up | Venue | Crowd |
| --- | --- | --- | --- | --- | --- | --- |
| 2011 | 10 June | Exiles | 16–12 | England | Headingley, Leeds | 14,174 |
| 2012 | 16 June | England | 18–10 | Exiles | Langtree Park, St. Helens | 11,083 |
| | 4 July | Exiles | 32–20 | England | Kirklees Stadium, Huddersfield | 7,865 |
| 2013 | 14 June | England | 30–10 | Exiles | Halliwell Jones Stadium, Warrington | 7,926 |

### Series wins

| Wins | Team |
| --- | --- |
| 2 | Exiles |
| 1 | England |

### Match wins

| Wins | Team |
| --- | --- |
| 2 | Exiles |
| 2 | England |

## Individual records

### Playing

#### England

#### Exiles

### Coaching

#### England

#### Exiles

## InfoBox

International Origin
|  | |
| --- | --- |
| Sport | Rugby league |
| Instituted | 2010 |
| Inaugural season | 2011 |
| Ceased | 2013 |
| Number of teams | 2 |
| Country | England (RFL) |
| Trophy Holders | England |
| Most titles | Exiles (2 titles) |
| Website | www.internationalorigin.com |
| Broadcast partner | Sky Sports |
| Related competition | State of Origin series |


title: Osterburg (Groothusen)

abstract: The Osterburg is a castle from the High Middle Ages in the village of Groothusen in the municipality of Krummhörn, in the district of Aurich in Lower Saxony, Germany.

text:
# Osterburg (Groothusen)

The **Osterburg** is a castle from the High Middle Ages in the village of Groothusen in the municipality of Krummhörn, in the district of Aurich in Lower Saxony, Germany.

## Location

The castles lies at the eastern end of the East Frisian village next to a protected landscape. Today it houses a large quantity of historical memorabilia.

## History

The village of Groothusen was originally built on a long warft in the early Middle Ages and was an important trading centre and meeting place in the Frisian Emsigerland, as well as the provost office for 12 parishes. At that time, like many other places in Krummhörn, it was on the edge of a bay and was accessible to shipping. There were, in those days, three moated castles in the village: the Osterburg, Middelburg and Westerburg. Only the Osterburg - rebuilt in 1490 - has survived; the other two were destroyed by Hamburg forces during feuds in 1400 and 1432.

The Osterburg, is surrounded by a moat in the middle of a park with an old lime tree avenue. The oldest part is a long, two-story hall, which was built around 1490 by the chieftain family of Beninga. Around 1550 the castle was converted into a three-winged manor house, when two lower wings were built in front of the hall. In 1700 the right wing was demolished to make way for a Gulf farmhouse, which was built in 1707. The last structural change to the Osterburg was carried out in 1900, when a hallway was built in front of the hall. So the form of the original building cannot be easily seen from the front. From the rear of the building there is however a view of the original stage of construction.

Today the Osterburg houses a significant collection of cultural and art historical artefacts such as furniture, weapons, a library, items of Old East Frisian culture and a remarkable art collection of ancestral portraits from five centuries.

The castle is now owned by the descendants of the chieftain family of Beninga and may be visited in guided tours arranged by telephone. The left wing has been extended to create guest rooms, where bed and breakfast is offered.

## Sources

* Kempe, Enno F. (1989). *Die Osterburg zu Groothusen* (Ostfriesische Kunstführer, Heft 12). Aurich. ISBN 3-925365-34-6

## InfoBox

| Osterburg | |
| --- | --- |
| Groothusen | |
|  | |
| OsterburgOsterburg | |
| Coordinates | 53°26′07″N 7°04′08″E / 53.435278°N 7.068889°E / 53.435278; 7.068889 |
| Type | Lowland castle |
| Code | DE-NI |
| Site information | |
| Condition | Preserved or largely preserved |
| Site history | |
| Built | around 1200 to 1300 |


title: Oscar Kawagley

abstract: Angayuqaq Oscar Kawagley, best known as Oscar Kawagley, was a Yup'ik anthropologist, teacher and actor from Alaska. He was an associate professor of education at the University of Alaska, Fairbanks until his death in 2011. The Anchorage Daily News described him as "one of (Alaska's) most influential teachers and thinkers".

text:
# Oscar Kawagley

**Angayuqaq Oscar Kawagley** (November 8, 1934 – April 27, 2011), best known as **Oscar Kawagley**, was a Yup'ik anthropologist, teacher and actor from Alaska. He was an associate professor of education at the University of Alaska, Fairbanks until his death in 2011. The *Anchorage Daily News* described him as "one of (Alaska's) most influential teachers and thinkers".

## Career

Kawagley's 1995 book *A Yupiaq Worldview: a Pathway to Ecology and Spirit* was an attempt to reconcile indigenous and Western worldviews from an indigenous perspective, and was an important contribution to the field of ethnoecology. In the book he developed the concept of "indigenous methodology", explaining how western science can benefit from native ways of understanding and vice versa.

Oscar's acting career included a major role in the independent 1991 film *Salmonberries*, starring k.d. lang. He appeared in the television show *Northern Exposure*, and contributed his voice to the elderly Denahi in the 2003 Disney film *Brother Bear*.\[https://en.m.wikipedia.org/wiki/Brother\_Bear}

## Death

He died of cancer in Fairbanks, Alaska, in 2011 at the age of 76. His ashes were scattered after his cremation.

## Publications

* Kawagley, A. O. (2006). A Yupiaq Worldview: A Pathway to Ecology and Spirit. United States: Waveland Press.

## Filmography

| Year | Title | Role | Notes |
| --- | --- | --- | --- |
| 1991 | *Salmonberries* | Butch |  |
| 2003 | *Brother Bear* | Old Denahi/Inuit Narrator | Voice, (final film role) |

## InfoBox

| Oscar Kawagley | |
| --- | --- |
| Born | Angayuqaq Oscar Kawagley
(1934-11-08)November 8, 1934
Bethel, Alaska, U.S. |
| Died | April 27, 2011(2011-04-27) (aged 76)
Fairbanks, Alaska, U.S. |
| Occupation(s) | Actor, teacher, anthropologist |


title: Interatomic potential

abstract: Interatomic potentials are mathematical functions to calculate the potential energy of a system of atoms with given positions in space. Interatomic potentials are widely used as the physical basis of molecular mechanics and molecular dynamics simulations in computational chemistry, computational physics and computational materials science to explain and predict materials properties. Examples of quantitative properties and qualitative phenomena that are explored with interatomic potentials include lattice parameters, surface energies, interfacial energies, adsorption, cohesion, thermal expansion, and elastic and plastic material behavior, as well as chemical reactions.

text:
# Interatomic potential

**Interatomic potentials** are mathematical functions to calculate the potential energy of a system of atoms with given positions in space. Interatomic potentials are widely used as the physical basis of molecular mechanics and molecular dynamics simulations in computational chemistry, computational physics and computational materials science to explain and predict materials properties. Examples of quantitative properties and qualitative phenomena that are explored with interatomic potentials include lattice parameters, surface energies, interfacial energies, adsorption, cohesion, thermal expansion, and elastic and plastic material behavior, as well as chemical reactions.

## Functional form

Interatomic potentials can be written as a series expansion of functional terms that depend on the position of one, two, three, etc. atoms at a time. Then the total potential of the system $\textstyle V\_{\mathrm {} }$ can be written as

$$V\_{\mathrm {} }=\sum \_{i=1}^{N}V\_{1}({\vec {r}\_{i})+\sum \_{i,j=1}^{N}V\_{2}({\vec {r}\_{i},{\vec {r}\_{j})+\sum \_{i,j,k=1}^{N}V\_{3}({\vec {r}\_{i},{\vec {r}\_{j},{\vec {r}\_{k})+\cdots }}}}}}$$

Here $\textstyle V\_{1}$ is the one-body term, $\textstyle V\_{2}$ the two-body term, $\textstyle V\_{3}$ the three body term, $\textstyle N$ the number of atoms in the system, $\vec {r}\_{i}$ the position of atom $i$, etc. $i$, $j$ and $k$ are indices that loop over atom positions.

Note that in case the pair potential is given per atom pair, in the two-body term the potential should be multiplied by 1/2 as otherwise each bond is counted twice, and similarly the three-body term by 1/6. Alternatively, the summation of the pair term can be restricted to cases $\textstyle i\<j$ and similarly for the three-body term $\textstyle i\<j\<k$, if the potential form is such that it is symmetric with respect to exchange of the $j$ and $k$ indices (this may not be the case for potentials for multielemental systems).

The one-body term is only meaningful if the atoms are in an external field (e.g. an electric field). In the absence of external fields, the potential $V$ should not depend on the absolute position of atoms, but only on the relative positions. This means that the functional form can be rewritten as a function of interatomic distances $\textstyle r\_{ij}=|{\vec {r}\_{i}-{\vec {r}\_{j}|}}$ and angles between the bonds (vectors to neighbours) $\textstyle \theta \_{ijk}$. Then, in the absence of external forces, the general form becomes

$$V\_{\mathrm {TOT} }=\sum \_{i,j}^{N}V\_{2}(r\_{ij})+\sum \_{i,j,k}^{N}V\_{3}(r\_{ij},r\_{ik},\theta \_{ijk})+\cdots $$

In the three-body term $\textstyle V\_{3}$ the interatomic distance $\textstyle r\_{jk}$ is not needed since the three terms $\textstyle r\_{ij},r\_{ik},\theta \_{ijk}$ are sufficient to give the relative positions of three atoms $i,j,k$ in three-dimensional space. Any terms of order higher than 2 are also called *many-body potentials*. In some interatomic potentials the many-body interactions are embedded into the terms of a pair potential (see discussion on EAM-like and bond order potentials below).

In principle the sums in the expressions run over all $N$ atoms. However, if the range of the interatomic potential is finite, i.e. the potentials $\textstyle V(r)\equiv 0$ above some cutoff distance $\textstyle r\_{\mathrm {cut} }$, the summing can be restricted to atoms within the cutoff distance of each other. By also using a cellular method for finding the neighbours, the MD algorithm can be an O(N) algorithm. Potentials with an infinite range can be summed up efficiently by Ewald summation and its further developments.

## Force calculation

The forces acting between atoms can be obtained by differentiation of the total energy with respect to atom positions. That is, to get the force on atom $i$ one should take the three-dimensional derivative (gradient) of the potential $V\_{\text{tot}}$ with respect to the position of atom $i$:

$$\vec {F}\_{i}=-\nabla \_{{\vec {r}\_{i}V\_{\mathrm {TOT} }}}$$

For two-body potentials this gradient reduces, thanks to the symmetry with respect to $ij$ in the potential form, to straightforward differentiation with respect to the interatomic distances $\textstyle r\_{ij}$. However, for many-body potentials (three-body, four-body, etc.) the differentiation becomes considerably more complex since the potential may not be any longer symmetric with respect to $ij$ exchange. In other words, also the energy of atoms $k$ that are not direct neighbours of $i$ can depend on the position $\textstyle {\vec {r}\_{i}}$ because of angular and other many-body terms, and hence contribute to the gradient $\textstyle \nabla \_{{\vec {r}\_{k}}}$.

## Classes of interatomic potentials

Interatomic potentials come in many different varieties, with different physical motivations. Even for single well-known elements such as silicon, a wide variety of potentials quite different in functional form and motivation have been developed. The true interatomic interactions are quantum mechanical in nature, and there is no known way in which the true interactions described by the Schrödinger equation or Dirac equation for all electrons and nuclei could be cast into an analytical functional form. Hence all analytical interatomic potentials are by necessity approximations.

Over time interatomic potentials have largely grown more complex and more accurate, although this is not strictly true. This has included both increased descriptions of physics, as well as added parameters. Until recently, all interatomic potentials could be described as "parametric", having been developed and optimized with a fixed number of (physical) terms and parameters. New research focuses instead on non-parametric potentials which can be systematically improvable by using complex local atomic neighbor descriptors and separate mappings to predict system properties, such that the total number of terms and parameters are flexible. These non-parametric models can be significantly more accurate, but since they are not tied to physical forms and parameters, there are many potential issues surrounding extrapolation and uncertainties.

### Parametric potentials

#### Pair potentials

The arguably simplest widely used interatomic interaction model is the Lennard-Jones potential

$$V\_{\mathrm {LJ} }(r)=4\varepsilon \left\[\left({\frac {\sigma }{r}\right)^{12}-\left({\frac {\sigma }{r}\right)^{6}\right\]}}$$

where $\textstyle \varepsilon $ is the depth of the potential well and $\textstyle \sigma $ is the distance at which the potential crosses zero. The attractive term proportional to $\textstyle 1/r^{6}$ in the potential comes from the scaling of van der Waals forces, while the $\textstyle 1/r^{12}$ repulsive term is much more approximate (conveniently the square of the attractive term). On its own, this potential is quantitatively accurate only for noble gases and has been extensively studied in the past decades, but is also widely used for qualitative studies and in systems where dipole interactions are significant, particularly in chemistry force fields to describe intermolecular interactions - especially in fluids.

Another simple and widely used pair potential is the Morse potential, which consists simply of a sum of two exponentials.

$$V\_{\mathrm {M} }(r)=D\_{e}(e^{-2a(r-r\_{e})}-2e^{-a(r-r\_{e})})$$

Here $\textstyle D\_{e}$ is the equilibrium bond energy and $\textstyle r\_{e}$ the bond distance. The Morse potential has been applied to studies of molecular vibrations and solids, and also inspired the functional form of more accurate potentials such as the bond-order potentials.

Ionic materials are often described by a sum of a short-range repulsive term, such as the Buckingham pair potential, and a long-range Coulomb potential giving the ionic interactions between the ions forming the material. The short-range term for ionic materials can also be of many-body character .

Pair potentials have some inherent limitations, such as the inability to describe all 3 elastic constants of cubic metals or correctly describe both cohesive energy and vacancy formation energy. Therefore, quantitative molecular dynamics simulations are carried out with various of many-body potentials.

##### Repulsive potentials

For very short interatomic separations, important in radiation material science, the interactions can be described quite accurately with screened Coulomb potentials which have the general form

$$V(r\_{ij})={1 \over 4\pi \varepsilon \_{0}{Z\_{1}Z\_{2}e^{2} \over r\_{ij}\varphi (r/a)}}$$

Here, $\varphi (r)\to 1$ when $r\to 0$. $Z\_{1}$ and $Z\_{2}$ are the charges of the interacting nuclei, and *$a$* is the so-called screening parameter. A widely used popular screening function is the "Universal ZBL" one. and more accurate ones can be obtained from all-electron quantum chemistry calculations In binary collision approximation simulations this kind of potential can be used to describe the nuclear stopping power.

#### Many-body potentials

The Stillinger-Weber potential is a potential that has a two-body and three-body terms of the standard form

$$V\_{\mathrm {TOT} }=\sum \_{i,j}^{N}V\_{2}(r\_{ij})+\sum \_{i,j,k}^{N}V\_{3}(r\_{ij},r\_{ik},\theta \_{ijk})$$

where the three-body term describes how the potential energy changes with bond bending. It was originally developed for pure Si, but has been extended to many other elements and compounds and also formed the basis for other Si potentials.

Metals are very commonly described with what can be called "EAM-like" potentials, i.e. potentials that share the same functional form as the embedded atom model. In these potentials, the total potential energy is written

$$V\_{\mathrm {TOT} }=\sum \_{i}^{N}F\_{i}\left(\sum \_{j}\rho (r\_{ij})\right)+{\frac {1}{2}\sum \_{i,j}^{N}V\_{2}(r\_{ij})}$$

where $\textstyle F\_{i}$ is a so-called embedding function (not to be confused with the force $\textstyle {\vec {F}\_{i}}$) that is a function of the sum of the so-called electron density $\textstyle \rho (r\_{ij})$. $\textstyle V\_{2}$ is a pair potential that usually is purely repulsive. In the original formulation the electron density function $\textstyle \rho (r\_{ij})$ was obtained from true atomic electron densities, and the embedding function was motivated from density-functional theory as the energy needed to 'embed' an atom into the electron density. . However, many other potentials used for metals share the same functional form but motivate the terms differently, e.g. based on tight-binding theory or other motivations .

EAM-like potentials are usually implemented as numerical tables. A collection of tables is available at the interatomic potential repository at NIST

Covalently bonded materials are often described by bond order potentials, sometimes also called Tersoff-like or Brenner-like potentials.

These have in general a form that resembles a pair potential:

$$V\_{ij}(r\_{ij})=V\_{\mathrm {repulsive} }(r\_{ij})+b\_{ijk}V\_{\mathrm {attractive} }(r\_{ij})$$

where the repulsive and attractive part are simple exponential functions similar to those in the Morse potential. However, the strength is modified by the environment of the atom $i$ via the $b\_{ijk}$ term. If implemented without an explicit angular dependence, these potentials can be shown to be mathematically equivalent to some varieties of EAM-like potentials Thanks to this equivalence, the bond-order potential formalism has been implemented also for many metal-covalent mixed materials.

EAM potentials have also been extended to describe covalent bonding by adding angular-dependent terms to the electron density function $\rho $, in what is called the modified embedded atom method (MEAM).

##### Force fields

A force field is the collection of parameters to describe the physical interactions between atoms or physical units (up to ~108) using a given energy expression. The term force field characterizes the collection of parameters for a given interatomic potential (energy function) and is often used within the computational chemistry community. The force field parameters make the difference between good and poor models. Force fields are used for the simulation of metals, ceramics, molecules, chemistry, and biological systems, covering the entire periodic table and multiphase materials. Today's performance is among the best for solid-state materials, molecular fluids, and for biomacromolecules, whereby biomacromolecules were the primary focus of force fields from the 1970s to the early 2000s. Force fields range from relatively simple and interpretable fixed-bond models (e.g. Interface force field, CHARMM, and COMPASS) to explicitly reactive models with many adjustable fit parameters (e.g. ReaxFF) and machine learning models.

### Non-parametric potentials

It should first be noted that non-parametric potentials are often referred to as "machine learning" potentials. While the descriptor/mapping forms of non-parametric models are closely related to machine learning in general and their complex nature make machine learning fitting optimizations almost necessary, differentiation is important in that parametric models can also be optimized using machine learning.

Current research in interatomic potentials involves using systematically improvable, non-parametric mathematical forms and increasingly complex machine learning methods. The total energy is then written $V\_{\mathrm {TOT} }=\sum \_{i}^{N}E(\mathbf {q} \_{i})$where $\mathbf {q} \_{i}$ is a mathematical representation of the atomic environment surrounding the atom $i$, known as the descriptor. $E$ is a machine-learning model that provides a prediction for the energy of atom $i$ based on the descriptor output. An accurate machine-learning potential requires both a robust descriptor and a suitable machine learning framework. The simplest descriptor is the set of interatomic distances from atom $i$ to its neighbours, yielding a machine-learned pair potential. However, more complex many-body descriptors are needed to produce highly accurate potentials. It is also possible to use a linear combination of multiple descriptors with associated machine-learning models. Potentials have been constructed using a variety of machine-learning methods, descriptors, and mappings, including neural networks, Gaussian process regression, and linear regression.

A non-parametric potential is most often trained to total energies, forces, and/or stresses obtained from quantum-level calculations, such as density functional theory, as with most modern potentials. However, the accuracy of a machine-learning potential can be converged to be comparable with the underlying quantum calculations, unlike analytical models. Hence, they are in general more accurate than traditional analytical potentials, but they are correspondingly less able to extrapolate. Further, owing to the complexity of the machine-learning model and the descriptors, they are computationally far more expensive than their analytical counterparts.

Non-parametric, machine learned potentials may also be combined with parametric, analytical potentials, for example to include known physics such as the screened Coulomb repulsion, or to impose physical constraints on the predictions.

## Potential fitting

Since the interatomic potentials are approximations, they by necessity all involve parameters that need to be adjusted to some reference values. In simple potentials such as the Lennard-Jones and Morse ones, the parameters are interpretable and can be set to match e.g. the equilibrium bond length and bond strength of a dimer molecule or the surface energy of a solid . Lennard-Jones potential can typically describe the lattice parameters, surface energies, and approximate mechanical properties. Many-body potentials often contain tens or even hundreds of adjustable parameters with limited interpretability and no compatibility with common interatomic potentials for bonded molecules. Such parameter sets can be fit to a larger set of experimental data, or materials properties derived from less reliable data such as from density-functional theory. For solids, a many-body potential can often describe the lattice constant of the equilibrium crystal structure, the cohesive energy, and linear elastic constants, as well as basic point defect properties of all the elements and stable compounds well, although deviations in surface energies often exceed 50%. Non-parametric potentials in turn contain hundreds or even thousands of independent parameters to fit. For any but the simplest model forms, sophisticated optimization and machine learning methods are necessary for useful potentials.

The aim of most potential functions and fitting is to make the potential *transferable*, i.e. that it can describe materials properties that are clearly different from those it was fitted to (for examples of potentials explicitly aiming for this, see e.g.). Key aspects here are the correct representation of chemical bonding, validation of structures and energies, as well as interpretability of all parameters. Full transferability and interpretability is reached with the Interface force field (IFF). An example of partial transferability, a review of interatomic potentials of Si describes that Stillinger-Weber and Tersoff III potentials for Si can describe several (but not all) materials properties they were not fitted to.

The NIST interatomic potential repository provides a collection of fitted interatomic potentials, either as fitted parameter values or numerical tables of the potential functions. The OpenKIM project also provides a repository of fitted potentials, along with collections of validation tests and a software framework for promoting reproducibility in molecular simulations using interatomic potentials.

## Machine-learned interatomic potentials

Since the 1990s, machine learning programs have been employed to construct interatomic potentials, mapping atomic structures to their potential energies. These are generally referred to as 'machine learning potentials' (MLPs) or as 'machine-learned interatomic potentials' (MLIPs). Such machine learning potentials help fill the gap between highly accurate but computationally intensive simulations like density functional theory and computationally lighter, but much less precise, empirical potentials. Early neural networks showed promise, but their inability to systematically account for interatomic energy interactions limited their applications to smaller, low-dimensional systems, keeping them largely within the confines of academia. However, with continuous advancements in artificial intelligence technology, machine learning methods have become significantly more accurate, positioning machine learning as a significant player in potential fitting.

Modern neural networks have revolutionized the construction of highly accurate and computationally light potentials by integrating theoretical understanding of materials science into their architectures and preprocessing. Almost all are local, accounting for all interactions between an atom and its neighbor up to some cutoff radius. These neural networks usually intake atomic coordinates and output potential energies. Atomic coordinates are sometimes transformed with atom-centered symmetry functions or pair symmetry functions before being fed into neural networks. Encoding symmetry has been pivotal in enhancing machine learning potentials by drastically constraining the neural networks' search space.

Conversely, message-passing neural networks (MPNNs), a form of graph neural networks, learn their own descriptors and symmetry encodings. They treat molecules as three-dimensional graphs and iteratively update each atom's feature vectors as information about neighboring atoms is processed through message functions and convolutions. These feature vectors are then used to directly predict the final potentials. In 2017, the first-ever MPNN model, a deep tensor neural network, was used to calculate the properties of small organic molecules. Advancements in this technology led to the development of Matlantis in 2022, which commercially applies machine learning potentials for new materials discovery. Matlantis, which can simulate 72 elements, handle up to 20,000 atoms at a time, and execute calculations up to 20 million times faster than density functional theory with almost indistinguishable accuracy, showcases the power of machine learning potentials in the age of artificial intelligence.

Another class of machine-learned interatomic potential is the Gaussian approximation potential (GAP), which combines compact descriptors of local atomic environments with Gaussian process regression to machine learn the potential energy surface of a given system. To date, the GAP framework has been used to successfully develop a number of MLIPs for various systems, including for elemental systems such as Carbon Silicon, and Tungsten, as well as for multicomponent systems such as Ge2Sb2Te5 and austenitic stainless steel, Fe7Cr2Ni.

## Reliability of interatomic potentials

Classical interatomic potentials often exceed the accuracy of simplified quantum mechanical methods such as density functional theory at a million times lower computational cost. The use of interatomic potentials is recommended for the simulation of nanomaterials, biomacromolecules, and electrolytes from atoms up to millions of atoms at the 100 nm scale and beyond. As a limitation, electron densities and quantum processes at the local scale of hundreds of atoms are not included. When of interest, higher level quantum chemistry methods can be locally used.

The robustness of a model at different conditions other than those used in the fitting process is often measured in terms of transferability of the potential.


title: Orrin Bacon

abstract: Orrin Bacon was an American miller and politician. Born in Barnstable, Massachusetts, Bacon moved to Wisconsin in 1848. He first settled in Janesville, Wisconsin and then in 1855 moved to Green County, Wisconsin living in Monticello, Wisconsin. Bacon was a miller. In 1871, Bacon served in the Wisconsin State Assembly and was a Republican. He then served in the Wisconsin State Senate in 1872 and 1873. Bacon died of influenza in Monticello, Wisconsin. He was buried at Lima Center Cemetery in Lima Center, Wisconsin.

text:
# Orrin Bacon

**Orrin Bacon** (October 4, 1820  November 17, 1893) was an American miller and politician.

Born in Barnstable, Massachusetts, Bacon moved to Wisconsin in 1848. He first settled in Janesville, Wisconsin and then in 1855 moved to Green County, Wisconsin living in Monticello, Wisconsin. Bacon was a miller. In 1871, Bacon served in the Wisconsin State Assembly and was a Republican. He then served in the Wisconsin State Senate in 1872 and 1873. Bacon died of influenza in Monticello, Wisconsin. He was buried at Lima Center Cemetery in Lima Center, Wisconsin.