Wednesday, 26 July 2017

The Delta Aquarid Meteors.

The Delta Aquarid Meteor Shower peaks each year on 27-28 July, when the shower can produce 10-20 meteors per hour. Best viewing this year is predicted to be between midnight and 2.00 am (this will be in local time wherever they are viewed from, as the time reflects the orientation of the planet to the rest of the Solar System), when the radiant point of the shower (point from which the meteors appear to radiate), which is close to the star Delta Aquari (hence the name) will be highest in the sky. At this time this year the Moon will be in a waxing crescent phase, so that viewing will be little impeded by moonlight.


The Delta Aquarids are thought to be caused by the Earth passing through the trail of Comet 96P/Machholz, where it encounters thousands of tiny dust particles shed from the comet as its icy surface is melted (strictly sublimated) by the heat of the Sun. 96P/Machholz is a short period, Jupiter Family Comet, crossing our orbit every 5.24 years, but the trail of particles shed by it forms a constant flow,

See also...

http://sciencythoughts.blogspot.co.uk/2017/04/gobekli-tepe-does-ancient-anatolian.html
http://sciencythoughts.blogspot.co.uk/2017/05/the-2017-eta-aquarid-meteors.html

http://sciencythoughts.blogspot.co.uk/2017/04/fireball-over-southern-united-sates.html
http://sciencythoughts.blogspot.co.uk/2017/04/the-lyrid-meteors.html
http://sciencythoughts.blogspot.co.uk/2017/03/fireball-over-northern-texas.html
http://sciencythoughts.blogspot.co.uk/2017/03/fireball-meteor-over-british-columbia.html

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Strongyloides stercoralis: Determining the origin of Human infection in a parasitic Nematode.

Parasitic Nematodes of the genus Strongyloides infect the guts of a wide range of Vertebrate hosts, including Birds, Reptiles, Amphibians, and Mammals, as well as Humans, livestock, and companion animals. Two species are known to infect Humans, Strongyloides fuelleborni, which has two subspecies, one found in tropical Africa and the other in Papua New Guinea, and Strongyloides stercoralis, which has a cosmopolitan distribution, though most infections occur in the tropics and subtropics, and which is also found in Dogs and Chimpanzees.

In a paper published in the journal Scientific Reports on 7 July 2017 a team of scientists led by Eiji Nagayasu of the Division of Parasitology at the University of Miyazaki published the result of a phylogenetic study of Strongyloides stercoralis, using four gene sets plus morphometric analysis. Nematodes were isolated from Humans from Japan, Myanmar, Thailand, Laos, Uganda, the Central African Republic and Tanzania, as well as Dogs from Japan and Myanmar and Chimpanzees from Tanzania, with a view to establishing a phylogenetic tree and potentially determining the origin of infection in Humans.

 
A Strongyloides stercoralis nematode. Oklahoma State University.

Nagayasu et al. found that the Nematodes could be divided into two main clades (groups with common ancestry), one of which contained all the Human derived worms, plus the Chimpanzee derived worms and all worms from Dog infections in Japan, and some of the worms from Dogs in Myanmar. The second clade was contained entirely worms obtained from Dogs in Myanmar. They interpret this data as indicating that Strongyloides stercoralis infection originated in Dogs and has spread to Humans during the two species’ long association. The first clade has apparently made the jump between Dogs and Humans (and subsequently to Chimpanzees, which are very similar to Humans in immunological terms), while the second clade not made this jump. 

Median-joining haplotype network for the mitochondrial Cox1 gene. Each circle represents one haplotype. The size of the circle represents the number of hosts that harbour the given haplotype. The colour inside the circle indicates the host species/geographical origin (country). Numbers beside the branches indicate the number of mutational steps between haplotypes (no number is shown in case of a single-step difference). Branch lengths are roughly proportional to the number of mutational steps. Nagayasu et al. (2017).

Interestingly, a previous study of Strongyloides stercoralis, published in 2014 that looked as a smaller number of gene-sets and which concentrated on infections in Cambodia, had also identified two major clades within the total population of Nematodes, one of which was associated principally with Dogs, but which was also found in some Humans. However, re-examination of this data reveals that all of the Humans infected with the second strain were immunocompromised individuals the HIV from Myanmar; HIV is known for its destruction of the immune system, and often individuals infected with it are infected by organisms which do not usually infect Humans, or even which are not usually pathogenic at all, suggesting that such individuals would be vulnerable to a strain of Nematodes which normally attacks only Dogs.

See also...

http://sciencythoughts.blogspot.co.uk/2015/04/tripius-gyraloura-sphaerularid-nematode.htmlhttp://sciencythoughts.blogspot.co.uk/2015/04/philometrid-nematodes-from-perciform.html
http://sciencythoughts.blogspot.co.uk/2015/03/a-new-species-of-capillariid-nematode.htmlhttp://sciencythoughts.blogspot.co.uk/2014/12/two-new-species-of-pinworms-from.html
http://sciencythoughts.blogspot.co.uk/2014/11/a-parasitic-heterakid-nematode-from.htmlhttp://sciencythoughts.blogspot.co.uk/2014/10/parasite-infections-in-german-soldiers.html
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Flooding leads to 111 known deaths as monsoon arives in Gujarat.

The number of known deaths has risen to 111 in flooding associated with the onset of the Asian summer monsoon in the Indian state of Gujarat after the bodies of a family of seventeen in the village of Khariya in Banaskantha District, and it is feared that many more bodies will be discovered as the floodwaters recede. Many of the worst ht areas were along the banks of the river Banas, where water was released from the Dantiwada Dam at an increased rate after floodwaters from Rajasthan threatened to overstress the dam. This led to a number of villages close to the river being inundated.  A similar release of waters from the Sipu Dam has also lead to flooding on the Sipu River.

Flooding in Banaskantha District, Gujarat, on 25 July 2017. IANS.

Monsoons are tropical sea breezes triggered by heating of the land during the warmer part of the year (summer). Both the land and sea are warmed by the Sun, but the land has a lower ability to absorb heat, radiating it back so that the air above landmasses becomes significantly warmer than that over the sea, causing the air above the land to rise and drawing in water from over the sea; since this has also been warmed it carries a high evaporated water content, and brings with it heavy rainfall. In the tropical dry season the situation is reversed, as the air over the land cools more rapidly with the seasons, leading to warmer air over the sea, and thus breezes moving from the shore to the sea (where air is rising more rapidly) and a drying of the climate. This situation is particularly intense in South Asia, due to the presence of the Himalayas. High mountain ranges tend to force winds hitting them upwards, which amplifies the South Asian Summer Monsoon, with higher winds leading to more upward air movement, thus drawing in further air from the sea. 

Diagrammatic representation of wind and rainfall patterns in a tropical monsoon climate. Geosciences/University of Arizona.

See also...

http://sciencythoughts.blogspot.co.uk/2017/04/explosion-kills-three-workers-at.htmlhttp://sciencythoughts.blogspot.co.uk/2015/07/landslide-kills-three-on-pune-mumbai.html
http://sciencythoughts.blogspot.co.uk/2015/06/flooding-feared-to-have-killed-at-least.htmlhttp://sciencythoughts.blogspot.co.uk/2015/06/landslide-kills-five-in-maharashtra.html
http://sciencythoughts.blogspot.co.uk/2014/07/at-least-41-dead-following-landslide.htmlhttp://sciencythoughts.blogspot.co.uk/2014/06/flooding-after-mumbai-hit-by-freak-waves.html
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Five killed by landslide at Ramu in Cox's Bazar District of Bangladesh.

Five people have been killed and another five injured by a landslide in the village of Ramu in the Cox's Bazar District of Chittagong, Bangladesh,which occurred at about 3.00 am local time  on Tuesday 25 July 2017. Two of the dead have been identifies as children aged five and seven, who were buried when a mass of mud engulfed their home, with their parents among the injured. In the 24 hours before the incident the area received about 20 cm of rain, associated with the Asian summer monsoon. Landslides are a common problem after severe weather, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall.

The approximate location of the 25 July 2017 Cox's Bazar landslide. Google Maps.

Monsoons are tropical sea breezes triggered by heating of the land during the warmer part of the year (summer). Both the land and sea are warmed by the Sun, but the land has a lower ability to absorb heat, radiating it back so that the air above landmasses becomes significantly warmer than that over the sea, causing the air above the land to rise and drawing in water from over the sea; since this has also been warmed it carries a high evaporated water content, and brings with it heavy rainfall. In the tropical dry season the situation is reversed, as the air over the land cools more rapidly with the seasons, leading to warmer air over the sea, and thus breezes moving from the shore to the sea (where air is rising more rapidly) and a drying of the climate. This situation is particularly intense in South Asia, due to the presence of the Himalayas. High mountain ranges tend to force winds hitting them upwards, which amplifies the South Asian Summer Monsoon, with higher winds leading to more upward air movement, thus drawing in further air from the sea. 

Diagrammatic representation of wind and rainfall patterns in a tropical monsoon climate. Geosciences/University of Arizona.

See also...

http://sciencythoughts.blogspot.co.uk/2017/07/student-killed-by-landslide-at.htmlhttp://sciencythoughts.blogspot.co.uk/2017/06/seven-confirmed-deaths-and-aeounf-150.html
http://sciencythoughts.blogspot.co.uk/2015/08/death-toll-thought-to-have-exceeded-120.htmlhttp://sciencythoughts.blogspot.co.uk/2015/06/flooding-and-landslides-kill-at-least.html
http://sciencythoughts.blogspot.co.uk/2015/02/one-killed-by-landslide-in-chittagong.htmlhttp://sciencythoughts.blogspot.co.uk/2013/07/two-women-killed-by-landslide-in.html
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Tuesday, 25 July 2017

Magnitude 2.3 Earthquake in the Scottish Highlands.

The British Geological Survey recorded a Magnitude 2.3 Earthquake at a depth of about 7 km about a kilometre to the northwestt of the village of Badrallach on the west coast of the Highland Region of Scotland, slightly before 8.00 am British Summertime (slightly before 7.00 am GMT) on Sunday 23 July 2017. This was not a major event, and presented no threat to human life or property, but was felt in several towns and villages in the area.

The approximate location of the 23 July 2017 Ballrallach Earthquake. Google Maps.

Earthquakes become more common as you travel north and west in Great Britain, with the west coast of Scotland being the most quake-prone part of the island and the northwest of Wales being more prone  to quakes than the rest of Wales or most of England. 
 
The precise cause of Earthquakes in the UK can be hard to determine; the country is not close to any obvious single cause of such activity such as a plate margin, but is subject to tectonic pressures from several different sources, with most quakes probably being the result of the interplay between these forces.
 
Britain is being pushed to the east by the expansion of the Atlantic Ocean and to the north by the impact of Africa into Europe from the south. It is also affected by lesser areas of tectonic spreading beneath the North Sea, Rhine Valley and Bay of Biscay. Finally the country is subject to glacial rebound; until about 10 000 years ago much of the north of the country was covered by a thick layer of glacial ice (this is believed to have been thickest on the west coast of Scotland), pushing the rocks of the British lithosphere down into the underlying mantle. This ice is now gone, and the rocks are springing (slowly) back into their original position, causing the occasional Earthquake in the process. 
 
 (Top) Simplified diagram showing principle of glacial rebound. Wikipedia. (Bottom) Map showing the rate of glacial rebound in various parts of the UK. Note that some parts of England and Wales show negative values, these areas are being pushed down slightly by uplift in Scotland, as the entire landmass is quite rigid and acts a bit like a see-saw. Climate North East.
  
Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. If you felt this quake, or were in the area but did not (which is also useful information) then you can report it to the British Geological Survey here.  
 
See also...
 
http://sciencythoughts.blogspot.co.uk/2016/05/magnitude-13-earthquake-in-northwest.htmlhttp://sciencythoughts.blogspot.co.uk/2015/12/magnitude-13-earthquake-in-highland.html
http://sciencythoughts.blogspot.co.uk/2015/07/magnitude-13-earthquake-near-glencoe.htmlhttp://sciencythoughts.blogspot.co.uk/2015/04/magnitude-22-earthquake-to-south-of.html
http://sciencythoughts.blogspot.co.uk/2015/03/earthquakes-on-either-side-of-loch.htmlhttp://sciencythoughts.blogspot.co.uk/2015/03/magnitude-14-earthquake-in-highland.html

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Monday, 24 July 2017

Asteroid 2017 NS5 passes the Earth.

Asteroid 2017 NS5 passed by the Earth at a distance of about 5 136 000 km (13.4 times the average distance between the Earth and the Moon, or 3.43% of the distance between the Earth and the Sun), at about 8.10 am GMT on Monday 17 July 2017. There was no danger of the asteroid hitting us, though were it to do so it would have presented a considerable threat. 2017 NS5 has an estimated equivalent diameter of 138-410 m (i.e. it is estimated that a spherical object with the same volume would be 138-410 m in diameter), and an object of this size would be predicted to be capable of passing through the Earth's atmosphere relatively intact, impacting the ground directly with an explosion that would be 3000-165 000 times as powerful as the Hiroshima bomb. Such an impact would result in an impact crater 2-7 km in diameter and devastation on a global scale, as well as climatic effects that would last decades or even centuries.

 Image of 2017 NS5 taken with the iTelescope T17 Deep Field Research Telescope at Siding Spring Observatory in New South Wales on 11 July 2017. The image is a composite of six fifty second exposures, the dotted lines being stars which have moved over the course of the exposures and the asteroid the faint object inset indicated by the arrow. Marian Urbanik/iTelescope/Fotografický občasník.

2017 NS5 was discovered on 10 July 2017 (seven days before its closest approach to the Earth) by the University of Hawaii's PANSTARRS telescope on Mount Haleakala on Maui. The designation 2017 NS5 implies that it was the 143rd asteroid (asteroid S5) discovered in the first half of July 2017 (period 2017 N).

The calculated orbit of 2017 NS1. Minor Planet Center.

2017 NS1 has a 353 day orbital period, with an elliptical orbit tilted at an angle of 44.0° to the plain of the Solar System which takes in to 0.72 AU from the Sun (72% of the distance at which the Earth orbits the Sun; slightly inside the orbit of the planet Venus) and out to 1.23 AU (23% further away from the Sun than the Earth). This means that close encounters between the asteroid and Earth are fairly common, with the last thought to have happened in July 2016 and the next predicted in July 2018. 2017 NS1 also has occasional close encounters with the planet Venus, with the next predicted for February 2148. Although it does cross the Earth's orbit and is briefly further from the Sun on each cycle, 2017 NS1 spends most of its time closer to the Sun than we are, and is therefore classified as an Aten Group Asteroid. As an asteroid probably larger than 150 m in diameter that occasionally comes within 0.05 AU of the Earth, 2017 NS1 is also classified as a Potentially Hazardous Asteroid.

See also...

http://sciencythoughts.blogspot.co.uk/2017/07/asteroid-2017-mc1-passes-earth.htmlhttp://sciencythoughts.blogspot.co.uk/2017/06/asteroid-2017-mf-passes-earth.html
http://sciencythoughts.blogspot.co.uk/2017/06/asteroid-2017-kw31-passes-earth.htmlhttp://sciencythoughts.blogspot.co.uk/2017/06/comet-c2015-v2-johnson-approaches-earth.html
http://sciencythoughts.blogspot.co.uk/2017/05/asteroid-2017-kh5-passes-earth.htmlhttp://sciencythoughts.blogspot.co.uk/2017/05/asteroid-2017-ky4-passes-earth.html
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