Sunday, August 2, 2020

Yemen's Multilayered Civil War: A Brief History

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Anant Jani

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Yemen's Multilayered Civil War: A Brief History


Global Views 360

Publication Date

August 2, 2020


Children in Yemen

Children in Yemen | Source: Rod Waddington via Flickr

This is the 1st part of a short explainer article series on the current crisis in Yemen.

Since 2015, Yemen has been at war on two different fronts, 1) The Civil War between the Iran-backed Houthi rebels and the UAE-Saudi Arabia backed government headed by Abdrabbuh Mansur Hadi, and 2) the war against the local terrorist outfits of Al-Qaeda and ISIS.

However, last year one more complexity was added to the conflict when UAE withdrew from the coalition backing Hadi government and later threw its support behind another secessionist force in southern Yemen, which seeks to re-create the State of South Yemen, as it was before the unification of Yemen in 1990.

As of early this year, it has added another layer to the war: the failing healthcare infrastructure and the rise of COVID-19.

The staggering cost of this war in the past five years has prompted the UN to name it the worst man-made humanitarian crisis in history, with Some 24 million Yemeni people - 80 percent of the country's population - requiring assistance or protection.

This series of articles seeks to build historical context to follow the current events in Yemen, believing much of the recent media coverage to have been ignored, or otherwise made wholly uncontextualized in the process of following the crisis for over a decade.

Yemen and the greater neighbourhood | Source: Google Map

The History

Much of the current conflict can only be understood as a result of the events of the latter half of the 20th century. Here is a brief look at the history that has shaped today’s wars in Yemen.

At the heart of several issues in the conflict is the fact that modern day Yemen was initially divided into North Yemen and South Yemen until 1990, when it was unified.

Yemen and the greater neighbourhood | Source: Wikimedia

North Yemen:

The Yemen Arab Republic (YAR), a coalition in North Yemen, overthrew the Mutawakilite Kingdom in 1970, which had been ruling since Yemen’s decolonization, in 1918. The YAR established their capital at Sana’a, a site which will often be the site of conflict in the following years.
This part of Yemen, during the cold war  was backed the countries aligned with the anti-communist block like Saudi Arabia, Jordan, the US, the UK and West Germany. The influence of Saudi Arabia and their relations with the US will come to play a greater role in the following decades.

South Yemen:

This referred to the region that was under the British Raj as the Aden Protectorate, since 1874. It consisted of two-thirds of present-day Yemen. In 1937 it became a Province of the British Raj, and in 1963, it collapsed and an emergency declared. The collapse was the joint effort of the National Liberation Front (NLF) and the Front for the Liberation of Occupied South Yemen (FLOSY).

Aden was used by the East India Company as a coal depot, and to stop Arab pirates from harassing British-India trade. Until 1937, Aden was part of British India, officially titled the Aden Protectorate.

Aden, like Sana’a will come to be the capital of southern Yemen, and the site of many conflicts.

This part of Yemen, during the cold war was backed by the Cummunist bloc countries like USSR, Cuba, and East Germany.

The Unification:

North and South Yemen united in 1990, after several years of conflict with one another. The leader of North Yemen, Ali Abdullah Saleh, was named President of unified Yemen in 1990. He was to continue ruling over Yemen for over three decades.

The unification of Yemen finally fulfilled almost a century of struggle that started during the British occupation and continued at different paces throughout the monarchy and cold war period. This unification also took away the privileges and power vested with many important tribes and people. Unlike the political forces, the armed forces of North and South Yemen were not unified at the time of political unification of the country.

The disgruntled former elites and the partisan army provided the fertile ground for the first civil war of Yemen which followed shortly after the unification.

Link to the second part.

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April 13, 2021 2:10 PM

Detecting The Ultra-High Energy Cosmic Rays With Smartphones

Smartphones have become the most commonplace objects in our daily lives. The unimaginable power that we hold in our hands is unrealized by most of us and, more importantly, untapped. Its creativity often gets misused but one can only hope that it’s fascinating abilities would be utilized. For example, did you know that the millions of phones around the globe can be connected to form a particle detector? The following article covers the CRAYFIS (Cosmic RAYs Found in Smartphones) phone-based application developed by the physicists from the University of California—Daniel Whiteson, Michael Mulhearn, and their team. CRAYFIS aims to take advantage of the large network of smartphones around the world and detect the cosmic or gamma rays bursts which enter the Earth’s atmosphere almost constantly.

What Are Cosmic Rays?

Cosmic rays are high velocity subatomic particles bombarding the Earth’s upper atmosphere continuously. Cosmic ray bursts have the highest energy compared to all forms of electro-magnetic radiation. When we say ultra-high energy particles (energy more than 1018^eV), we mean two million times more energetic than the ones that can be produced by the particle colliders on Earth.  These rays are thought to be more powerful than typical supernovae and can release trillions of times more energy than the Sun. They are also highly unpredictable as they can enter Earth’s atmosphere from any direction and the bursts can last for any period of time ranging from a few thousand seconds to several minutes.

Despite many theoretical hypotheses, the sources of these ultra-high energy cosmic rays are still a mystery to us even after many decades of their discovery. These rays were initially discovered in the 1960’s by the U.S. military when they were doing background checks for gamma rays after nuclear weapon testing. Cosmologists suggest that these bursts could be the result of super massive stars collapsing - leading to hypernova; or can be retraced to collisions of black holes with other black holes or neutron stars.

How Do We Detect Them?

When the high-energy particles collide with the Earth’s atmosphere, the air and the gas molecules cause them to break apart and create massive showers of relatively low-energy particles. Aurora borealis i.e., the Northern and the Southern lights are the lights that are emitted when these cosmic rays interact with the Earth’s magnetic field. Currently, these particles are hitting the Earth at a rate of about one per square meter per second. The showers get scattered to a radius of one or two kilometers consisting mostly of high-energy photons, electrons, positrons and muons. But the fact that these particles can hit the Earth anytime and anywhere is where the problem arises. Since the Earth has a massive area, it is not possible to place a detector everywhere and catch them at the exact moment.

Energetic charged particles known as cosmic rays hit our atmosphere, where they collide with air molecules to produce a shower of secondary particle | Source: CERN

Detecting such a shower requires a very big telescope, which logically means a network of individual particle detectors distributed over a mile or two-wide radius and connected to each other. The Pierre Auger Observatory in South America is the only such arrangement where 1,600 particle detectors have been scattered on 3,000 square kilometers of land. But the construction cost of the same was about $100 million. Yet, only a few cosmic ray particles could be detected using this arrangement. How do we spread this network around the Earth?

In addition to being cost-effective, such a setup must also be feasible. The Earth’s surface cannot possibly be dotted with particle detectors which cost huge fortunes. This is where smartphones come into the picture.

Detecting The Particles Using Smartphones

Smartphones are the most appropriate devices required to solve the problem. They have planet wide coverage, are affordable by most people and are being actively used by more than 1.5 billion users around the planet. Individually, these devices are low and inefficient; but a considerably dense network of such devices can give us a chance to detect cosmic ray showers belonging to the highest energy range.

Previous research has shown that smartphones have the capability of detecting ionizing radiation. The camera is the most sensitive part of the smartphone and is just the device required to meet our expectations. A CMOS (Complementary Metal Oxide Semiconductor) device is present in the camera- in which silicon photodiode pixels produce electron-hole pairs when struck by visible photons (when photons are detected by the CMOS device, it leaves traces of weakly activated pixels). The incoming rays are also laced with other noises and interference from the surroundings.  Although these devices are made to detect visible light, they still have the capability of detecting higher-energy photons and also low-ionizing particles such as the muons.

A screenshot from the app which shows the exposure time, the events- the number of particles recorded and other properties

To avoid normal light, the CRAYFIS application is to be run during nighttime with the camera facing down. As the phone processor runs the application it collects data from its surroundings using a camera as its detector element. The megapixel images (i.e., the incoming particles) are scanned at a speed of 5 to 15 frames per second, depending on the frame-processing speed of the device. Scientists expect that signals from the cosmic rays would occur rarely, i.e., around one in 500 frames. Also, there is the job of removing background data. An algorithm was created to tune the incoming particle shower by setting a threshold frequency at around 0.1 frames per second. Frames containing pixels above the threshold are stored and passed to the second stage which examines the stored frames, saving only the pixels above a second, lower threshold.

The CRAYFIS app is designed to run when the phone is not being used and when it is connected to a power source. The actual performance would be widely affected by the geometry of the smartphone’s camera and the conditions in which the data is being collected. Further, once the application is installed and is in the operating mode, no participation is required from the user, which is required to achieve wide-scale participation. When a Wifi connection is available the collected data would be uploaded to the central server so that it could be interpreted.

There is much complicated math used to trace back the information collected from the application. The most important parameters for the app are the local density of incoming particles, the detection area of the phone and the particle identification efficiency. These parameters are used to find the mean number of candidates (photons or muons) being detected. Further, the probability that a phone will detect no candidates or the probability that a phone will detect one or more candidates is given by Poisson distribution. The density of the shower is directly proportional to the incident particle energy with a distribution in x and y sensitive to the direction in which the particle came from. An Unbinned Likelihood (it is the probability of obtaining a certain data- in this case the distribution of the cosmic rays including their energy and direction, the obtained data is arranged into bins which are very, very small) analysis is used to determine the incident particle energy and direction. To eliminate background interference, a benchmark requirement has been set that at least 5 phones must detect and register a hit to be considered as a candidate.

It is impossible to express just how mind-blowing this innovation is. As the days pass, Science and Technology around us keep on surprising us and challenge us to rack our brains for more and more unique ways to deal with complex problems. The CRAYFIS app is simply beautiful and it would be a dream-come-true to the scientists if the project works out and we are able to detect these high energy, super intimidating cosmic rays with smartphones from our backyard.

Further Reading

The paper by Daniel Whiteson and team can be found here.

An exciting book “We Have No Idea” by Daniel Whiteson and cartoonist Jorge Cham can be found here.

The CRAYFIS app can be found here.

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