Category Science

When we talk about tectonic or lithospheric plates, we mean the sections into which the lithosphere is cracked. The surface of the Earth is divided into 7 major and 8 minor plates. The largest plates are the Antarctic, Eurasian, and North American plates.

The mechanism by which tectonic plates move is still a subject of much debate among Earth scientists. The Earth is dynamic thanks to its internal heat, which comes from deep within the mantle from the breakdown of radioactive isotopes. It was long thought that this resulted in convection currents in the mantle which were responsible for the movement of tectonic plates across the Earth’s surface – indeed this is still the most common idea illustrated in many textbooks and on the internet. However, this theory is now largely out of favour, with modern imaging techniques unable to identify mantle convection cells that are sufficiently large to drive plate movement. Some plate models show that two thirds of the Earth’s surface move faster than the underlying mantle so there appears to be little or no evidence that convection currents in the mantle move plates (apart maybe from some very small plates in unusual circumstances).

Where slab pull is not the main plate driver, ‘ridge push’ is another possibility. As the lithosphere formed at divergent plate margins is hot, and less dense than the surrounding area it rises to form oceanic ridges. The newly-formed plates slide sideways off these high areas, pushing the plate in front of them resulting in a ridge-push mechanism.

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The amygdaloid body is also known as the amygdaloid nucleus. This is an oval structure located within the temporal lobe of the human brain. The structure is a small part of the brain and is closely associated with the hypothalamus, cingulated gyrus, and hippocampus.

The amygdala is an important part of the brain, which assists in responses of fear and pleasure. The abnormal working of the amygdaloid body can lead to various clinical conditions including developmental delay, depression, anxiety, and autism.

A simple view of the information processing through the amygdala follows as- the amygdala sends projections to the hypothalamus, the dorsomedial thalamus, the thalamic reticular nucleus, the nuclei of the trigeminal nerve and the facial nerve, the ventral tegmental area, the locus coeruleus, and the laterodorsal tegmental nucleus. The basolateral amygdala projects to the nucleus accumbens, including the medial shell.

The amygdala is also involved in the modulation of memory consolidation. Following any learning event, the long-term memory for the event is not formed instantaneously. Rather, information regarding the event is slowly assimilated into long-term (potentially lifelong) storage over time, possibly via long-term potentiation. Recent studies suggest that the amygdala regulates memory consolidation in other brain regions. Also, fear conditioning, a type of memory that is impaired following amygdala damage, is mediated in part by long-term potentiation.

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The Arecibo Telescope was primarily used for research in radio astronomy, atmospheric science, and radar astronomy, as well as for programs that search for extraterrestrial intelligence (SETI). Scientists wanting to use the observatory submitted proposals that were evaluated by independent scientific referees. NASA also used the telescope for near-Earth object detection programs. The observatory, funded primarily by the National Science Foundation (NSF) with partial support from NASA, was managed by Cornell University from its completion in 1963 until 2011, after which it was transferred to a partnership led by SRI International. In 2018, a consortium led by the University of Central Florida assumed operation of the facility.

Since its completion in November 1963, the Telescope had been used for radar astronomy and radio astronomy, and had been part of the Search for extraterrestrial intelligence (SETI) program. It was also used by NASA for Near-Earth object detection. Since around 2006, NSF funding support for the telescope had waned as the Foundation directed funds to newer instruments, though academics petitioned to the NSF and Congress to continue support for the telescope. Numerous hurricanes, including Hurricane Maria, had damaged parts of the telescope, straining the reduced budget.

Two cable breaks, one in August 2020 and a second in November 2020, threatened the structural integrity of the support structure for the suspended platform and damaged the dish. The NSF determined in November 2020 that it was safer to decommission the telescope rather than to try to repair it, but the telescope collapsed before a controlled demolition could be carried out. The remaining support cables from one tower failed around 7:56 a.m. local time on December 1, 2020, causing the receiver platform to fall into the dish and collapsing the telescope.

In late 2020, Wanda Vázquez Garced, then governor of Puerto Rico signed an executive order for $8 million for the removal of debris and for the design of a new observatory to be built in its place. The governor stated reconstruction of the observatory is a “matter of public policy”. The executive order also designated the area as a history site.

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The ASKAP telescope makes images of radio signals from the sky, allowing astronomers to view the Universe at wavelengths that our eyes cannot see. It is a type of radio telescope known as an ‘interferometer’. This means it uses many antennas acting together as one large telescope. In our case, ASKAP has 36 dish antennas spread out over six kilometres in outback Western Australia.

ASKAP’s key feature is its wide field of view, generated by its unique chequerboard Phased Array Feed (PAF) receivers. Together with specialised digital systems, a PAF creates 36 separate (simultaneous) beams on the sky which are mosaicked together into a large single image. This gives ASKAP the ability to rapidly survey large areas of the sky – making it one of the world’s fastest survey radio telescopes. ASKAP will help to answer some of the most fundamental questions of 21st century astronomy and astrophysics involving dark matter, dark energy, the nature of gravity, the origins of the first stars, the evolution of galaxies and the properties of magnetic fields in space.

ASKAP is located at CSIRO’s Murchison Radio-astronomy Observatory (MRO) in Western Australia (WA). The MRO is about 700 kilometres north of Perth in the Murchison Shire, on the traditional lands of the Wajarri Yamaji. Situated in Mid West WA, the Shire covers an area of 49,500 square kilometers and has a population of 120 people.

This remote location is ideal for radio astronomy as there is minimal interference from Earth-based radio transmissions. In the same way that it is necessary for us to avoid city-lights when we’re looking up at the stars, radio telescopes must avoid other radio communication networks that disrupt the signals being received from space.  

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