вторник, 16 октября 2018 г.

Treatment in Sight This large green-coloured mass visible…

Treatment in Sight

This large green-coloured mass visible inside a patient’s eye is a uveal melanoma. Arising from the pigmented cells of the eye, such as those in the iris, uveal melanomas are rare but often fatal, killing approximately half of the patients in whom they develop. Such tumours may be treated with surgical removal of the eye or radiation therapy prior to metastasis, but once the cancer has spread, effective treatments are limited. But now scientists have discovered a natural plant compound, derived from a member of the primrose family, that inhibits the growth of uveal melanoma cells in culture. The flower substance binds tightly to an oncogenic – cancer driving – protein in the melanoma cells preventing its activity and, in so doing, either kills the cells or turns them back into apparently normal uveal cells. The next step is to test this primrose compound in animal models of uveal cancer.

Written by Ruth Williams

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All in the Family: Kin of Gravitational-Wave Source Discovered

GRB 150101B

Credit X-ray: NASA/CXC/GSFC/UMC/E. Troja et al.; 

Optical and infrared: NASA/STScI

A distant cosmic relative to the first source that astronomers detected in both gravitational waves and light may have been discovered, as reported in our latest press release. This object, called GRB 150101B, was first detected by identified as a gamma ray burst (GRB) by NASA’s Fermi Gamma-ray Space Telescope in January 2015.

This image shows data from NASA’s Chandra X-ray Observatory (purple in the inset boxes) in context with an optical image of GRB 150101B from the Hubble Space Telescope.

The detection and follow-up observations with Chandra, Hubble, the Discovery Channel Telescope, the Neil Gehrels Swift Observatory, and other telescopes show GRB 150101B shares remarkable similarities to the neutron star merger and gravitational wave source discovered by Advanced Laser Interferometer Gravitational Wave Observatory (LIGO) and its European counterpart Virgo in 2017 known as GW170817. In this view of GRB 150101B and its host galaxy, the Chandra field of view is outlined as a box on an optical and infrared image from the Hubble Space Telescope. Chandra images are included from two different times (labeled in the insets) to show how the X-ray source faded with time.

The latest study concludes that these two separate objects may, in fact, be related. The discovery suggests that events like GW170817 and GRB 150101B could represent a whole new class of erupting objects that turn on and off in X-rays and might actually be relatively common.

The researchers think both GRB 150101B and GW170817 were most likely produced by the same type of event: the merger of two neutron stars, a catastrophic coalescence that generated a narrow jet, or beam, of high-energy particles. The jet produced a short, intense burst of gamma rays (known as a short GRB), a high-energy flash that can last only seconds. GW170817 proved that these events may also create ripples in space-time itself called gravitational waves.

While there are many commonalities between GRB 150101B and GW170817, there are two very important differences. One is their location. GW170817 is about 130 million light years from Earth, while GRB 150101B lies about 1.7 billion light years away. Even if Advanced LIGO had been operating in early 2015, it would very likely not have detected gravitational waves from GRB 150101B because of its greater distance.

It is possible that a few mergers like the ones seen in GW170817 and GRB 150101B had been detected as short GRBs before but had not been identified with other telescopes. Without detections at longer wavelengths like X-rays or optical light, GRB positions are not accurate enough to determine what galaxy they are located in.

In the case of GRB 150101B, astronomers thought at first that the counterpart was an X-ray source detected by Swift in the center of the galaxy, likely from material falling into a supermassive black hole. However, follow-up observations with Chandra, with its sharp X-ray resolution, detected the true counterpart away from the center of the host galaxy. This can be seen in the Chandra images. Not only has the source dimmed dramatically, it is clearly outside the center of the galaxy, which appears as the constant brighter source to the upper right.

A paper describing this result by Eleonora Troja (Goddard Space Flight Center and the University of Maryland at College Park) and colleagues appears in the October 16, 2018, issue of the journal Nature Communications and is available online. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra’s science and flight operations.

Fast Facts for GRB 150101B:

Scale: Full field image:~41 arcmin across (300,000 light years across) Inset: ~12 arcsec across( 90,000 light years across)
Category: Supernovas & Supernova Remnants, Neutron Stars/X-ray Binaries
Coordinates (J2000): RA 12h 32m 04.96s | Dec -10° 56′ 00.7″
Constellation: Virgo
Observation Date: Jan 9 & Feb 10, 2015
Observation Time: 20 hours 39 minutes
Obs. ID: 17586 & 17594
Instrument: ACIS
References: E. Troja et al., 2018, Nature Communications (in press); arXiv:1806.10624
Color Code: X-ray (purple); Optical/IR (red/green)
Distance Estimate: About 1.7 billion light years (z=0.1341)

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2018 October 16 Jupiter in Ultraviolet from Hubble Image…

2018 October 16

Jupiter in Ultraviolet from Hubble
Image Credit: NASA, ESA, Hubble; Processing & License: Judy Schmidt

Explanation: Jupiter looks a bit different in ultraviolet light. To better interpret Jupiter’s cloud motions and to help NASA’s robotic Juno spacecraft understand the planetary context of the small fields that it sees, the Hubble Space Telescope is being directed to regularly image the entire Jovian giant. The colors of Jupiter being monitored go beyond the normal human visual range to include both ultraviolet and infrared light. Featured from 2017, Jupiter appears different in near ultraviolet light, partly because the amount of sunlight reflected back is distinct, giving differing cloud heights and latitudes discrepant brightnesses. In the near UV, Jupiter’s poles appear relatively dark, as does its Great Red Spot and a smaller (optically) white oval to the right. The String of Pearl storms farther to the right, however, are brightest in near ultraviolet, and so here appear (false-color) pink. Jupiter’s largest moon Ganymede appears on the upper left. Juno continues on its looping 53-day orbits around Jupiter, while Earth-orbiting Hubble is now recovering from the loss of a stabilizing gyroscope.

∞ Source: apod.nasa.gov/apod/ap181016.html

HiPOD (15 October 2018): All Rocks and No Central Peak Make…

HiPOD (15 October 2018): All Rocks and No Central Peak Make Kamativi a Dull Crater

   – This crater is named for a town in Zimbabwe, which is probably not dull at all. (257 km above the surface. Black and white is less than 5 km across; enhanced color is less than 1 km.)

NASA/JPL/University of Arizona

Captioned Image Spotlight: Dramatic Changes over the South Polar…

Captioned Image Spotlight: Dramatic Changes over the South Polar Residual Cap

The South Polar residual cap is composed of carbon dioxide ice that persists through each Martian summer. However, it is constantly changing shape.

The slopes get more direct illumination at this polar location, so they warm up and sublimate, going directly from a solid state to a gaseous state. The gas then re-condenses as frost over flat areas, building new layers as the older layers are destroyed. This animation compares a small subarea to the same locale imaged in 2009.

NASA/JPL/University of Arizona

Massive star’s unusual death heralds the birth of compact neutron star binary

Carnegie’s Anthony Piro was part of a Caltech-led team of astronomers who observed the peculiar death of a massive star that exploded in a surprisingly faint and rapidly fading supernova, possibly creating a compact neutron star binary system. Piro’s theoretical work provided crucial context for the discovery. Their findings are published by Science.

Massive star's unusual death heralds the birth of compact neutron star binary
The three panels represent moments before, when and after the faint supernova iPTF14gqr, visible in the middle panel,
appeared in the outskirts of a spiral galaxy located 920 million light years away from us. The massive star that died
in the supernova left behind a neutron star in a very tight binary system. These dense stellar remnants will ultimately
spiral into each other and merge in a spectacular explosion, giving off gravitational and electromagnetic waves
[Credit: SDSS/Caltech/Keck]

Observations made by the Caltech team–including lead author Kishalay De and project principal investigator Mansi Kasliwal (herself a former-Carnegie postdoc)–suggest that the dying star had an unseen companion, which gravitationally siphoned away most of the star’s mass before it exploded as a supernova. The explosion is believed to have resulted in a neutron star binary, suggesting that, for the first time, scientists have witnessed the birth of a binary system like the one first observed to collide by Piro and a team of Carnegie and UC Santa Cruz astronomers in August 2017.

A supernova occurs when a massive star–at least eight times the mass of the Sun–exhausts its nuclear fuel, causing the core to collapse and then rebound outward in a powerful explosion. After the star’s outer layers have been blasted away, all that remains is a dense neutron star–an exotic star about the size of a city but containing more mass than the Sun.

Usually, a lot of material–many times the mass of the Sun–is observed to be blasted away in a supernova. However, the event that Kasliwal and her colleagues observed, dubbed iPTF 14gqr, ejected matter only one fifth of the Sun’s mass.

“We saw this massive star’s core collapse, but we saw remarkably little mass ejected,” Kasliwal says. “We call this an ultra-stripped envelope supernova and it has long been predicted that they exist. This is the first time we have convincingly seen core collapse of a massive star that is so devoid of matter.”

Piro’s theoretical modeling guided the interpretation of these observations. This allowed the observers to infer the presence of dense material surrounding the explosion.

“Discoveries like this demonstrate why it has been so important to build a theoretical astrophysics group at Carnegie,” Piro said. “By combining observations and theory together, we can learn so much more about these amazing events.”

The fact that the star exploded at all implies that it must have previously had a lot of material, or its core would never have grown large enough to collapse. But where was the missing mass hiding? The researchers inferred that the mass must have been stolen by a compact companion star, such as a white dwarf, neutron star, or black hole.

The neutron star that was left behind from the supernova must have then been born into orbit with this compact companion. Because this new neutron star and its companion are so close together, they will eventually merge in a collision. In fact, the merger of two neutron stars was first observed in August 2017 by Piro and a team of Carnegie and UC Santa Cruz astronomers, and such events are thought to produce the heavy elements in our universe, such as gold, platinum, and uranium.

The event was first seen at Palomar Observatory as part of the intermediate Palomar Transient Factory (iPTF), a nightly survey of the sky to look for transient, or short-lived, cosmic events like supernovae. Because the iPTF survey keeps such a close eye on the sky, iPTF 14gqr was observed in the very first hours after it had exploded. As the earth rotated and the Palomar telescope moved out of range, astronomers around the world collaborated to monitor iPTF 14gqr, continuously observing its evolution with a number of telescopes that today form the Global Relay of Observatories Watching Transients Happen (GROWTH) network of observatories.

Source: Carnegie Institution For Science [October 11, 2018]



Aussie telescope almost doubles known number of mysterious ‘fast radio...

Australian researchers using a CSIRO radio telescope in Western Australia have nearly doubled the known number of ‘fast radio bursts’— powerful flashes of radio waves from deep space. The team’s discoveries include the closest and brightest fast radio bursts ever detected. Their findings were reported in the journal Nature.

Aussie telescope almost doubles known number of mysterious 'fast radio bursts'
Artist’s impression of CSIRO’s Australian SKA Pathfinder (ASKAP) radio telescope observing ‘fast radio bursts’
 in ‘fly’s eye mode’. Each antenna points in a slightly different direction, giving maximum sky coverage
[Credit: OzGrav, Swinburne University of Technology]

Fast radio bursts come from all over the sky and last for just milliseconds. Scientists don’t know what causes them but it must involve incredible energy—equivalent to the amount released by the Sun in 80 years.
“We’ve found 20 fast radio bursts in a year, almost doubling the number detected worldwide since they were discovered in 2007,” said lead author Dr. Ryan Shannon, from Swinburne University of Technology and the OzGrav ARC Centre of Excellence.

“Using the new technology of the Australia Square Kilometre Array Pathfinder (ASKAP), we’ve also proved that fast radio bursts are coming from the other side of the Universe rather than from our own galactic neighbourhood.”

Aussie telescope almost doubles known number of mysterious 'fast radio bursts'
An artist’s impression of CSIRO’s ASKAP radio telescope detecting a fast radio burst (FRB).
Scientists don’t know what causes FRBs but it must involve incredible
 energy – equivalent to the amount released by the Sun in 80 years
[Credit: OzGrav, Swinburne University of Technology]

Co-author Dr. Jean-Pierre Macquart, from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), said bursts travel for billions of years and occasionally pass through clouds of gas.

“Each time this happens, the different wavelengths that make up a burst are slowed by different amounts,” he said.

“Eventually, the burst reaches Earth with its spread of wavelengths arriving at the telescope at slightly different times, like swimmers at a finish line.

Aussie telescope almost doubles known number of mysterious 'fast radio bursts'
For each burst, the top panels show what the FRB signal looks like when averaged over all frequencies.
The bottom panels show how the brightness of the burst changes with frequency.
The bursts are vertical because they have been corrected for dispersion
[Credit: Ryan Shannon and the CRAFT collaboration]

“Timing the arrival of the different wavelengths tells us how much material the burst has travelled through on its journey.
“And because we’ve shown that fast radio bursts come from far away, we can use them to detect all the missing matter located in the space between galaxies—which is a really exciting discovery.”

CSIRO’s Dr. Keith Bannister, who engineered the systems that detected the bursts, said ASKAP’s phenomenal discovery rate is down to two things.

Aussie telescope almost doubles known number of mysterious 'fast radio bursts'
Antennas of CSIRO’s Australian SKA Pathfinder with the Milky Way overhead
[Credit: Alex Cherney/CSIRO]

“The telescope has a whopping field of view of 30 square degrees, 100 times larger than the full Moon,” he said.

“And, by using the telescope’s dish antennas in a radical way, with each pointing at a different part of the sky, we observed 240 square degrees all at once—about a thousand times the area of the full Moon.”

“ASKAP is astoundingly good for this work.”

A fast radio burst leaves a distant galaxy, travelling to Earth over billions of years and occasionally passing through clouds 

of gas in its path. Each time a cloud of gas is encountered, the different wavelengths that make up a burst are slowed by 

different amounts. Timing the arrival of the different wavelengths at a radio telescope tells us how much material the burst 

has travelled through on its way to Earth and allows astronomers to to detect “missing” matter located in the space between

 galaxies. Using CSIRO’s Australia Square Kilometre Array Pathfinder (ASKAP), astronomers have proved that fast radio

bursts are coming from the other side of the Universe rather than from our own galactic neighbourhood 

[Credit: CSIRO/ICRAR/OzGrav/Swinburne University of Technology]

Dr. Shannon said we now know that fast radio bursts originate from about halfway across the Universe but we still don’t know what causes them or which galaxies they come from.

The team’s next challenge is to pinpoint the locations of bursts on the sky. “We’ll be able to localise the bursts to better than a thousandth of a degree,” Dr. Shannon said.

“That’s about the width of a human hair seen ten metres away, and good enough to tie each burst to a particular galaxy.”

Dr Ryan Shannon (Swinburne/OzGrav), Dr Jean-Pierre Macquart (Curtin/ICRAR) and Dr Keith Bannister (CSIRO) 

describe their discovery of 20 new fast radio bursts (FRBs) and how the Phased Array Feed (PAF) receiver 

technology in CSIRO’s Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope 

enabled this breakthrough science [Credit: CSIRO]

ASKAP is located at CSIRO’s Murchison Radio-astronomy Observatory (MRO) in Western Australia and is a precursor for the future Square Kilometre Array (SKA) telescope.

The SKA could observe large numbers of fast radio bursts, giving astronomers a way to study the early Universe in detail.

The researchers and their institutions acknowledge the Wajarri Yamaji as the traditional owners of the MRO site.

Source: International Centre for Radio Astronomy Research [October 10, 2018]



Researcher warns of possible reprise of worst known drought, famine

A Washington State University researcher has completed the most thorough analysis yet of The Great Drought — the most devastating known drought of the past 800 years — and how it led to the Global Famine, an unprecedented disaster that took 50 million lives. She warns that the Earth’s current warming climate could make a similar drought even worse.

Researcher warns of possible reprise of worst known drought, famine
Engraving of two children in the Bellary district of the Madras Presidency, British India 
during the Great Famine of 1876–78 [Credit: WikiCommons]

Deepti Singh, an assistant professor in WSU’s School of the Environment, used tree-ring data, rainfall records and climate reconstructions to characterize the conditions leading up to the Great Drought, a period of widespread crop failures in Asia, Brazil and Africa from 1875 to 1878.

“Climate conditions that caused the Great Drought and Global Famine arose from natural variability. And their recurrence — with hydrological impacts intensified by global warming — could again potentially undermine global food security,” she and her colleagues write in the Journal of Climate. The paper comes as a United Nations report this week predicts that rising worldwide temperatures will bring about more frequent food shortages and wildfires as soon as 2040.

The Global Famine is among the worst humanitarian disasters in history, comparable to the influenza epidemic of 1918-1919, World War I or World War II. As an environmental disaster, it has few rivals. Making matters worse were social conditions, like British colonialists hoarding and exporting grain from India. Some populations were particularly vulnerable to disease and colonial expansion afterwards.

“In a very real sense, the El Niño and climate events of 1876-78 helped create the global inequalities that would later be characterized as ‘first’ and ‘third worlds’,” writes Singh, who was inspired by “Late Victorian Holocausts: El Niño Famines and the Making of the Third World.” The book details the social impact of the Great Drought and subsequent droughts in 1896-1897 and 1899-1902. Its author, Mike Davis, is a distinguished professor at the University of California, Riverside, and a co-author on Singh’s paper.

Despite its impact, few studies have characterized the dynamics of the drought, and Singh’s analysis is the first global-scale analysis of climatic conditions at the time.

“This is the first time that somebody is taking multiple sources of data — like rain gauges and tree-ring drought atlases that let us go back 500 and 800 years (respectively) — as well as multiple datasets of past climatic conditions, to quantify the severity of this event and the severity of the conditions that led to it,” Singh said.

The Great Drought actually was several droughts, Singh found, beginning with a failure of India’s 1875 monsoon season. East Asia’s drought started in the spring of 1876, followed by droughts in parts of South Africa, northern Africa and northeastern Brazil. There were also droughts in western Africa, Southeast Asia and Australia.

The length and severity of the droughts prompted the Global Famine, aided in no small part by one of the strongest known El Niños, the irregular but recurring periods of warm water in the tropical Pacific Ocean. That triggered the warmest known temperatures in the North Atlantic Ocean and the strongest known Indian Ocean dipole — an extreme temperature difference between warm waters in the west and cool waters in the east. These in turn triggered one of the worst droughts across Brazil and Australia.

Because the drought was induced by natural variations in sea-surface temperatures, says Singh, a similar global-scale event could happen again. Moreover, rising greenhouse gas concentrations and global warming are projected to intensify El Niño events, in which case “such widespread droughts could become even more severe.”

The socio-political factors that led to the famine no long exist, she notes. Still, she writes, “such extreme events would still lead to severe shocks to the global food system with local food insecurity in vulnerable countries potentially amplified by today’s highly connected global food network.”

Singh’s work was supported by a fellowship from Columbia University’s Lamont-Doherty Earth Observatory, where she collaborated with several of the paper’s co-authors. She continued working on the paper after arriving at WSU Vancouver this June.

Author: Eric Sorensen | Source: Washington State University [October 11, 2018]



Study of penguin colonies at Antarctic island shows decline

Results from a 21-year study into the breeding success of gentoo penguins at a well-known tourist site in Antarctica, reveal a 25 percent reduction in breeding pairs and a decrease of between 54-60 percent in chick numbers. Reporting this week in the journal Biodiversity and Conservation, researchers from British Antarctic Survey (BAS) say that the causes of the local decline is unclear.

Study of penguin colonies at Antarctic island shows decline
Ten colonies of gentoo penguin (Pygoscelis papua) inhabit Gouldier Island,
Port Lockroy [Credit: BAS]

During the study period there have been many changes: the number of visitors to Goudier Island, Port Lockroy on the Antarctic Peninsula increased on average by around 22 percent per year; at the same time, environmental conditions have changed with warmer air temperatures and changes in the duration of local sea-ice cover. The researchers say their analyses present a complex situation with different possible drivers. The potential link between an increase in visitors and the decline in the number of birds lead the authors to recommend new precautions in management of the site and the initiation of similar studies at other frequently visited sites.

The research team monitored ten gentoo penguin colonies on the small island. Six of those colonies are accessible to visitors under strict guidelines during the summer breeding season. The study also examined breeding success at four other ‘closed’ colonies, to which access is forbidden. The data were collected by the seasonal team from the UK Antarctic Heritage Trust (UKAHT) who manages Port Lockroy, the historic site on the island.

Lead author of the study Dr. Mike Dunn said, “We began this long-term study in 1996/97. For many years there appeared to be no adverse impact on the birds. Breeding success fluctuates greatly from year to year, so it is important to take a long-term view to understand the overall trend. The environmental change that we’ve seen in the Antarctic Peninsula region means that these penguins may also be vulnerable to changes in temperature and sea ice conditions. Our study suggests that it is sensible to review management of this heritage site and to conduct similar studies at other visited areas to determine whether or not the gentoo population decline is indeed a direct consequence of increasing numbers of visitors, or local environmental conditions.”

Port Lockroy, Base A, is Historic Site No 61 under the Antarctic Treaty. The former British Antarctic Survey research station and the only surviving base from a second world-war mission, is currently home to approximately 550 breeding pairs of gentoo penguins. The UK Antarctic Heritage Trust (UKAHT) actively manages the physical heritage of human endeavour in Antarctica (at Port Lockroy and five other former British Bases on the Antarctic Peninsula) through a sustainable conservation programme to recognise and conserve Britain’s long history of exploration and scientific research. UKAHT staff carry out annual monitoring of the breeding success of the gentoos on behalf of the British Antarctic Survey.

Camilla Nichol is Chief Executive of UKAHT. She says,”This study is an integral part of our operation on Goudier Island. Gathering data in this way enables us all to better understand all factors involved in changes in wildlife populations, and is fundamental to our responsible custodianship of this historic site. Visits to the island are managed under strict guidelines under the Antarctic Treaty and we work in partnership with the Antarctic Treaty system and the Antarctic tour operators to implement these guidelines. We will continue our work with these stakeholders to discuss the implications of these new findings in detail.”

Study of penguin colonies at Antarctic island shows decline
Tourists at Port Lockroy, Goudier Island, Antarctic Peninsula [Credit: BAS]

Port Lockroy (British Base A) is situated on Goudier Island in the Antarctic Peninsula. It was the first permanent British base in Antarctica established by a secret naval operation during the Second World War. It became Britain’s first wintering science station in the Antarctic and operated until its closure n 1962. After a survey of all the abandoned scientific bases in Antarctica in 1994 it was recognised for its historic significance. Port Lockroy was designated Historic Site and Monument No. 61 under the Antarctic Treaty in 1995. The buildings were restored in 1996 by a team from the British Antarctic Survey and have since been open to visitors during the Antarctic summer ever since. UKAHT took over the running of Port Lockroy in 2006. It is one of six historic sites cared for by UKAHT on the Antarctic Peninsula, and is the only one to have staff regularly based there each season.

Port Lockroy is one of 42 sites in the Antarctic Peninsula which have site guidelines to manage visitors. These site guidelines are agreed and adopted by the multi-lateral Committee for Environmental Protection (CEP) to the Antarctic Treaty; a committee comprising scientists, national Antarctic program managers, diplomats and environmentalists.

About gentoo penguins

In 2016 the IUCN Red List of threatened species re-classified gentoo penguins from ‘near threatened’ to ‘least concern.”

The Latin name pygoscelis, means brush tailed. Gentoos have the most prominent tail of all penguins, which sticks out behind and sweeps from side to side as they walk.

They have white patches extending from their eyes and a bright red-orange beak. No one knows where the name ‘gentoo’ came from, but they are one of the least numerous Antarctic penguins, with an estimated 387,000 breeding pairs.

Gentoo penguins are less likely to stick together than other penguins and can be found in small groups, sometimes with other species. Although, compared with some other species, they are less strongly attached to the same nest site (they have plenty of choice of sites), their pair-bonding is strong, and they usually mate with the same partner as the previous year.

Unusually for penguins, their breeding times are not well synchronised and their breeding success fluctuates greatly from year to year.

They nest on low hilltops or open beaches. When available, they make a nest with pebbles and other objects, and sometimes use a scrape in the ground. They lay two eggs and defend their nests fiercely. In southern locations the first and second-born chicks are equally likely to survive, but the second chick to hatch in more northerly islands often fails. If both eggs fail, breeding may sometimes take place again. Once hatched, the chicks join the crèche about a month later.

There are large differences in gentoo penguins from different locations. Fledging is far quicker in the south (62–82 days) than in the north (85–117 days) and gentoos from the south are smaller than their northerly relatives. Young gentoo penguins are very adventurous and have been spotted on the coasts of New Zealand and Africa.

Researchers think that the gentoos that currently breed at Port Lockroy first established a colony in 1985. UKAHT carries out annual monitoring of the breeding success of the gentoos on behalf of the British Antarctic Survey. The study has been ongoing since 1996 in order to determine the impact of visitation on their breeding success.

Source: British Antarctic Survey [October 11, 2018]



Do lizards dream like us?

Researchers from the Sleep Team at the Lyon Neuroscience Research Center (CNRS / INSERM / Claude Bernard Lyon 1 University / Université Jean Monnet), together with a colleague from the MECADEV research laboratory (CNRS / Muséum National d’Histoire Naturelle) have confirmed that lizards exhibit two sleep states, just like humans, other mammals, and birds. They corroborated the conclusions of a 2016 study on the bearded dragon (Pogona vitticeps) and conducted the same sleep investigation on another lizard, the Argentine tegu (Salvator merianae). Their findings, published in PLOS Biology, nevertheless point out differences between species, which raises new questions about the origin of sleep states.

Do lizards dream like us?
In addition to replicating the 2016 bearded dragon experiment, researchers conducted a new investigation using
another species of lizard, the Argentine tegu (Salvator merianae) [Credit: Paul-Antoine Libourel]

During sleep, the body carries out many vital activities: consolidation of knowledge acquired during the day, elimination of metabolic waste from the brain, hormone production, temperature regulation, and replenishment of energy stores. It would appear that this physiological phenomenon is shared by all members of the animal kingdom and has been preserved throughout evolution. But scientists long thought that only land mammals and birds experienced two separate sleep states: slow-wave sleep and REM, or paradoxical, sleep. The latter, associated with dreaming, is a complex phase during which the body exhibits behaviors in limbo between those of sleeping and waking hours.
A study whose findings were published by Science in 2016 focused on the bearded dragon (Pogona vitticeps) and demonstrated that this lizard also entered two distinct sleep states. It further hypothesized that such sleep states originated in a common ancestor of mammals and reptiles, 350 million years ago.

The team of researchers from the CNRS and Claude Bernard Lyon 1 University began by replicating the 2016 bearded dragon experiment. They then conducted a new investigation using another species of lizard, the Argentine tegu (Salvator merianae). Their data confirm both lizards go into two distinct sleep states bearing similarity to slow-wave and REM sleep, respectively.

But their analysis of behavioral, physiological, and cerebral parameters dug deeper and revealed differences not only between the sleep of the lizards and the sleep of both mammals and birds, but also between the two lizard species. Although human REM sleep is characterized by cerebral and ocular activity similar to that observed while awake, the corresponding state in both lizard species is associated with slower eye movements and, in the case of the tegu, cerebral activity very unlike that of waking hours.

These differences observed by the researchers paint a more complex picture of REM sleep in the animal kingdom and open new doors for investigations into the origin of our own sleep patterns and dreams . . . and those of lizards.

Source: CNRS [October 11, 2018]



Space Station Science Highlights: Week of Oct 8, 2018

ISS – Expedition 57 Mission patch.

Oct. 15, 2018

Last week’s departure of Expedition 56 astronauts marked the start of Expedition 57 and a new commander of the International Space Station, Alexander Gerst of the European Space Agency. Current crew members also include NASA astronauts Serena Auñón-Chancellor and Russian cosmonaut Sergey Prokopyev.

The Soyuz MS-10 spacecraft carrying Nick Hague of NASA and Alexey Ovchinin of the Russian space agency Roscosmos launched from the Baikonur Cosmodrome in Kazakhstan at 3:40 a.m. CDT on Thursday. Shortly after launch, an anomaly with the booster resulted in an abort of the ascent to orbit and a ballistic landing of the spacecraft in Kazakhstan. Hague and Ovchinin were recovered from the capsule and are in good condition. Crew aboard the station were informed and continue to operate the station and conduct important scientific research.

Image above: NASA astronaut Nick Hague and Alexey Ovchinin of Roscomos launched from the Baikonur Cosmodrome in Kazakhstan at 3:40 a.m. CDT on Thursday. Shortly after launch, an anomaly with the booster resulted in an abort of the ascent to orbit and a ballistic landing of the spacecraft in Kazakhstan. Both are in good condition. Image Credit: NASA.

Research last week included investigations related to human health and performance, and growing better protein crystals.

Advancing DNA and RNA sequencing in space continues

Crew members conducted operations with the Biomolecule Sequencer for the BEST investigation. This study seeks to advance use of DNA and RNA sequencing in space, using sequencing to identify microbial organisms living on the space station and to help determine how humans, plants and microbes adapt to life there.

Image above: The Biomolecule Extraction and Sequencing Technology (BEST) biomolecule sequencer floats in the International Space Station above a view of Earth. Image Credit: NASA.

Samples collected for ongoing look at effects of spaceflight

For the Biochemical Profile investigation, a crew member collected blood and urine samples at 120 days into spaceflight. The investigation tests blood and urine samples before, during, and after spaceflight to analyze biomarkers, or specific proteins and chemicals in the samples used as indicators of health. Scientists can use a database of post-flight analysis of samples and test results to study the effects of spaceflight on the human body.

A cooler way to create crystals

The crew prepared JAXA LT PCG samples and placed them in the Stirling-Cycle Refrigerator (FROST) to begin the process of producing high-quality protein crystals in microgravity at low temperatures. This new technique contributes to the development of new drugs by revealing disease-related protein structure, and to the production of new catalysts for the environmental and energy industries.

Animation above: The JAXA LT PCG investigation grows high quality protein crystals in microgravity to determine protein structures in detail. Last week, crew members prepared the samples and placed them in the FROST facility aboard the station. Animation Credit: NASA.

And a closer look at crystal formation

Also last week, crew members reconfigured the Fluids Integrated Rack (FIR) Light Microscopy Module (LMM) Biophysics facility for the LMM Biophysics 4 investigation. Proteins are important biological molecules that, when crystallized, provide better views of their structure that help scientists understand how they work. Proteins crystallized in microgravity are often higher in quality than those grown on Earth, and LMM Biophysics 4 examines the movement of single protein molecules in microgravity in order to determine why this is so.

International Space Station (ISS). Animation Credit: NASA

Other work was done on these investigations:

– Food Acceptability examines changes in how food appeals to crew members during their time aboard the station. Acceptability of food – whether crew members like and actually eat something – may directly affect crew caloric intake and associated nutritional benefits: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7562

– Sextant Navigation tests a hand-held sextant instrument that could provide emergency navigation for future manned spacecraft: https://www.nasa.gov/mission_pages/station/research/news/Sextant_ISS

– BCAT-CS studies dynamic forces between sediment particles that cluster together: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7668

– The Life Sciences Glovebox (LSG) is a sealed work area that accommodates life science and technology investigations in a workbench-type environment. Due to its larger size, two crew members can work in the LSG simultaneously: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=7676

– Meteor is a visible spectroscopy instrument used to observe meteors in Earth orbit: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1174

– ACME E-FIELD Flames studies the stability and sooting behavior of flames in microgravity to support development of less polluting and more efficient combustion technology for use on Earth: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=2058

Related articles:

Crew in Good Condition After Booster Failure:

Soyuz MS-10 – Emergency landing after a failure:

Related links:

Expedition 57: https://www.nasa.gov/mission_pages/station/expeditions/expedition57/index.html

BEST: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7687

Biochemical Profile: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=980

JAXA LT PCG: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=2031

LMM Biophysics 4: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7741

Spot the Station: https://spotthestation.nasa.gov/

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Images (mentioned), Animations (mentioned), Text, Credits: NASA/Michael Johnson/Vic Cooley, Lead Increment Scientist Expeditions 57/58.

Best regards, Orbiter.chArchive link

Clues from a Somalian cavefish about modern mammals’ dark past

After millions of years living in constant darkness, a species of blind cavefish found only in Somalia has lost an ancient system of DNA repair. That DNA repair system, found in organisms including bacteria, fungi, plants, and most other animals, harnesses energy from visible light to repair DNA damage induced by ultraviolet (UV) light.

Clues from a Somalian cavefish about modern mammals' dark past
A Somalian blind cavefish that, after evolving for millions of years in darkness, has lost the capacity
 to harness light for repairing DNA [Credit: Luca Scapoli at the University of Ferrara]

The findings reported in journal Current Biology are intriguing in part because only placental mammals, the group including people, were previously known to lack this system. Researchers say that the discovery supports the “nocturnal bottleneck” theory, which holds that the ancestors of modern mammals lived a subterranean or exclusively nocturnal existence as a strategy to avoid being eaten by dinosaurs.

“We have revealed in a species of blind cavefish the loss of an ancient DNA repair system that is highly conserved,” says Nicholas Foulkes of Karlsruhe Institute of Technology, Germany. “Curiously, the only other animals previously known to lack photoreactivation DNA repair are placental mammals. So, what we see in this species of cavefish may be the first stages in a process that happened before in our ancestors in the Mesozoic era.”

Foulkes’s team, including first author Haiyu Zhao, in collaboration with Cristiano Bertolucci at the University of Ferrara, Italy, is interested in understanding evolution in extreme environmental conditions and especially changes in DNA repair systems. The cavefish known as Phreatichthys andruzzii represented an ideal model for their studies because it has lived without any exposure to UV or visible light from the sun for more than 3 million years.

The researchers found that P. andruzzii carries mutations that disrupt the function of essential DNA repair genes. It also lacks a regulatory enhancer element, which coordinates and enhances DNA repair in response to sunlight in other species by turning other genes “on.”

Foulkes says that other cavefish species that have not been isolated in their cave environments for as long as P. andruzzii show normal, or even enhanced, photoreactivation mechanisms. Therefore, the new findings “highlight a more extreme level of adaptation in P. andruzzii compared with other cavefish species.”

The findings add to evidence that modern mammals once lived in darkness.

“Many features of modern mammals, such as the anatomy and function of the eye, show tell-tale features of a nocturnal life style,” Foulkes says. “It means we can now more confidently predict that mammalian ancestors experienced a prolonged period of evolution in complete darkness.”

The researchers say that they plan to study other DNA repair systems in the cavefish. They’re also curious to explore the links between the circadian clock and DNA repair, both mechanisms that rely on sunlight to function normally.

Source: Cell Press [October 11, 2018]



Smallest ever Tylosaurus fossil sheds light on species

The smallest Tylosaurus mosasaur fossil ever found has been revealed in a new study in the Journal of Vertebrate Paleontology and surprisingly it lacks a trademark feature of the species.

Smallest ever Tylosaurus fossil sheds light on species
From left to right a partial snout with teeth and tooth bases, partial braincase, and a section of upper jaw
with tooth bases [Credit: Ms. Christina Byrd, Paleontology Collections Manager
at the Sternberg Museum of Natural History in Hays, Kansas]

The fossil, likely to be that of a newborn, does not have the recognizable long snout typically seen in the species. The lack of this snout initially perplexed researchers, who struggled to identify which group of mosasaurs it belonged to.
After examining and comparing the fossil to young specimens of closely-related species, such as T. nepaeolicus and T. proriger which already had identifiable noses, researchers finally deemed it to be a young Tylosaurus.

Lead author Professor Takuya Konishi, of the Department of Biological Sciences at the University of Cincinnati said, “Having looked at the specimen in 2004 for the first time myself, it too took me nearly 10 years to think out of that box and realize what it really was—a baby Tylosaurus yet to develop such a snout.

Smallest ever Tylosaurus fossil sheds light on species
Comparison of a juvenile (L) and neonate (R) Tylosaurus fossil
[Credit: Historical Biology]

For those 10 years or so, I had believed too that this was a neonate of Platecarpus, a medium-sized (5-6m) and short-snouted mosasaur, not Tylosaurus, a giant (up to 13m) mosasaur with a significantly protruding snout.”
The lack of snout in the baby specimen found suggests to researchers that the development of this feature happens extremely quickly, between birth and juvenile stage—something that previous studies on the species had failed to notice.

Konishi further commented, “Yet again, we were challenged to fill our knowledge gap by testing our preconceived notion, which in this case was that Tylosaurus must have a pointy snout, a so-called ‘common knowledge.’

Smallest ever Tylosaurus fossil sheds light on species
The neonate fossil next to the fully formed Tylosaurus skull measuring 1.2m
[Credit: Historical Biology]

As individual development and evolutionary history are generally linked, the new revelation hints at the possibility that Tylosaurus adults from much older rock units may have been similarly short-snouted, something we can test with future discoveries.”

The fragments found include a partial snout with teeth and tooth bases, partial braincase, and a section of upper jaw with tooth bases. From this, they can estimate the entire baby skull to have been around 30cm (1ft) in total.

Tylosaurus belong to one of the largest-known groups of mosasaurs, up to 13m long, the front 1.8 m of that body being its head. The baby, therefore, was about 1/6 the size of such an adult.

Michael J. Everhart, a Kansas native and a special curator of paleontology at the Sternberg Museum of Natural History, Hays, Kansas, found the tiny specimens in 1991 in the lower Santonian portion of the Niobrara Chalk, in Kansas, which are now housed at the museum. The paper was co-authored by Paulina Jiménez-Huidobro and Michael W. Caldwell of the University of Alberta, Canada.

Source: Taylor & Francis [October 11, 2018]



Archaeology can help us prepare for climates ahead – not just look back

Watching the weather for today and tomorrow is relatively easy with apps and news programs – but knowing what the climate was like in the past is a little more difficult, writes Amy Prendergast, Lecturer in Physical Geography, University of Melbourne.

Archaeology can help us prepare for climates ahead – not just look back
Remains of meals at Haua Fteah cave reveal a lot about past climates in in the Gebel Akhdar region of Libya
[Credit: Amy Prendergast]

Archaeological evidence can show us how humans coped with long-gone seasonal and environmental changes. For me, it’s fascinating because it reveals what life was like back then. But it’s useful beyond that too. This body of data helps us understand and build resilience to climate change in the modern world.

Archaeological data is now of a standard where it can map past climate variability, offer context for human-induced climate change, and even improve future climate predictions.

Surviving all the seasons

As Earth takes its annual trip around the Sun, temperature, daylight hours and water availability vary through the seasons. These dictate natural cycles of animal breeding and migration, and plant fruiting and flowering. Such cycles control the availability of food, shelter, and raw material resources.

People living in cities might notice the changing seasons: autumn leaves turn a golden hue, and in summer fresh berries fill the supermarket shelves.

However, modern technology and global trade networks lessen the impact of the seasons on our daily lives. We can buy strawberries at any time of year (if we pay a premium). We can escape summer heatwaves by turning on air conditioners.

In most parts of Australia, our lives no longer depend on tracking the changes in plants and animals throughout the year. But in the past, if you weren’t in tune with seasonal patterns, you wouldn’t survive.

In my work I study how past people interacted with seasonal changes, using evidence from archaeological sites around the world.

Past and present seasonal patterns have changed due to climate change, causing cooler winters, warmer summers, or altered rainfall. Different seasons may occur earlier or later, last longer or be more extreme.

These changes have flow-on effects that can be detected in the archaeological record.

Life in ancient Libya

One archaeological site where seasonal changes have been well studied is the Haua Fteah cave in the Gebel Akhdar region of Libya.

Archaeology can help us prepare for climates ahead – not just look back
The entrance to the Haua Fteah cave site, Libya [Credit: Giulio Lucarini, University of Cambridge]

The Haua Fteah covers the transitions from prehistoric hunter-gatherers (beginning around 150,000 years ago), and prehistoric farmers (beginning around 7,500 years ago), right the way through to more recent times.

We found the Haua Fteah experienced the most arid and highly seasonal conditions just after the last global ice age. This changed the plant and animal resources available in the local landscape over 17,000 to 15,000 years ago.

However, despite the climate and resource instability, human activity was the most intense during this period.

To investigate this, we compared climate records from the Gebel Akhdar and adjacent regions of North Africa.

It turns out that even though the Gebel Akhdar had an arid and highly seasonal climate, it was not as arid as surrounding regions at this time. Scientists believe that increasingly dry conditions elsewhere led to population increases at the Haua Fteah – people were simply seeking a less hostile place to live.

Archaeology can help us prepare for climates ahead – not just look back
Amy Prendergast excavating a shell rich layer from the archaeological site of Haua Fteah
[Credit: Giulio Lucarini, University of Cambridge]

Additionally, use of shellfish as a food source changed from a predominantly winter-focused activity to a year-round activity during this period.

Year-round shellfish reliance was probably an adaptation to supplement the diet when other resources were less available. A mixture of climate and population pressures likely drove the restriction of resources and reliance on shellfish.

But beyond just knowing what people ate, and when, hiding in such shells (and other items) are clues about regional differences in seasonality.

Here’s how it works.

The remains of ancient meals

Archaeologists are essentially trash sifters. We use clues preserved in artefacts, plant and animal remains that people threw away or left behind to reconstruct the past.

Archaeology can help us prepare for climates ahead – not just look back
Marine mollusc shells (Phorcus turbinatus) from the Haua Fteah archaeological site
[Credit: Amy Prendergast]

Hard animal parts, including mollusc shells, teeth, fish ear bones (otoliths) and antlers, are routinely preserved in archaeological sites. These items accumulate from hunting, fishing, farming, and foraging activities.

The growth of these animal parts over time forms periodic growth rings, or increments. Much like tree rings in dendrochronology, the structure and chemical composition of these increments is influenced by the environment. By analysing these increments, we can understand what the environmental conditions during the animal’s life may have been like.

Seasonal variations in climate parameters such as temperature, rainfall, and humidity can be reconstructed by analysing the chemical composition of these growth increments using the presence of stable isotopes and trace elements.

Analyses of the annual—and in some cases, fortnightly, daily and even tidal—increments allow us to reconstruct a detailed timeline of environmental change. This field of study is known as sclerochronology and it has expanded exponentially in the past couple of decades.

The shells, teeth and animal bones that we analyse are the remains of food collected and consumed by people. Therefore climate reconstructions from them can be directly linked to human activity.

Archaeology can help us prepare for climates ahead – not just look back
Image of shell growth increments from a limpet shell. A shows where the shell is cut to reveal the cross section in B.
The shell cross section in C has been stained to enhance the visibility of the increments
[Credit: Amy Prendergast]

We can establish the animal’s season of death and season of exploitation by humans by examining the growth pattern or chemistry of the most recent growth increment. For example, we can use oxygen isotopes to reconstruct the sea surface temperature when the animal died. A very cool temperature tells us that the animal was collected by humans during the winter.

My colleagues and I recently wrote a review article and edited a journal special issue highlighting some of the latest research using these methods. The studies – which included evidence from prehistoric hunter-gatherers in the Mediterranean to historic Inuit sites in Canada – show how people dealt with seasonal variability in the past.

Learning from the past

Climate change is one of the most pressing issues in today’s world. However, our understanding of how human-induced climate change fits into natural climate variability (pre-industrial) is limited by the instrumental record, which rarely extends beyond a century or so.

Proxy records of past climate variability—such as increments from animal teeth or mollusc shells—extend our understanding of long-term climate variability.

Such abundant archaeological evidence can fill in the gaps from climate records about seasonal and sub-seasonal variation.

We need the robust, quantitative, detailed data we are now getting from archaeological sites around the globe. It helps to contextualise current and future climate change, and to form baselines for environmental monitoring.

Additionally, these climate records are useful for testing and refining global and regional climate models. More accurate climate models give us a better understanding of the overall climate system, and an enhanced ability to predict future climate change.

Such data may help us build resilience to climate change in our modern world.

So next time you tuck into your shellfish dinner, or juicy steak, take a moment to reflect on all of the useful information preserved in the intricate hard parts these creatures leave behind.

Will archaeologists of the future study your discarded shells and bones?

Author: Amy Prendergast | Source: The Conversation [October 12, 2018]



Quantifying evolutionary impacts of humans on the biosphere is harder than it seems

Are human disturbances to the environment driving evolutionary changes in animals and plants? A new study conducted by McGill researchers finds that, on average, human disturbances don’t appear to accelerate the process of natural selection. While the finding may seem reassuring, this unexpected pattern could reflect the limited number of species for which data were available.

Quantifying evolutionary impacts of humans on the biosphere is harder than it seems
Researchers might be studying species that fare relatively better in such environments than the average species
on Earth because one can only study selection in species that survive in impacted environments
[Credit: Andrew Hendry]

Many studies have shown that species evolve in response to human activity at a pace that exceeds natural rates: fish species often become smaller as humans selectively harvest the biggest fish; weeds and insect pests are becoming resistant to pesticides, and pathogens are becoming more resistant to antibiotics.
Rapid evolution in response to human activities could be caused by a strengthening of natural selection, a key influence on the pace of evolution. To better understand the extent to which this occurs, Vincent Fugère and Andrew Hendry from McGill’s Department of Biology reviewed thousands of scientific papers on the topic.

Of these, they retained 40 that provide estimates of “selection strength—the extent to which a particular trait is linked to survival or reproductive success (‘Darwinian fitness’)—in both human-disturbed and natural environments. These cases included, for instance, a weed species found in grasslands sprayed or not sprayed with herbicides; another involved a shark population before and after the construction of a beach resort that induced altered the local mangrove habitat.

From the 40 selected studies, the authors compiled 1,366 estimates covering 102 traits in 37 different species. They then used statistical models to test if there was an overall trend of stronger selection in human-disturbed conditions. While some disturbances caused very strong human-induced selection, others weakened selection, leading to no net effect on average when pooling all available studies.

“We are not arguing that human disturbances do not cause evolution; in fact, I certainly believe the opposite,” says Fugère, lead author of the new paper published in Proceedings of the National Academy of Sciences.

Rather, the finding, which is likely to surprise some evolutionary biologists, highlights the challenges of quantifying evolutionary impacts of humans on the biosphere.

For example, most species in the authors’ database performed well (had higher ‘fitness’) in the disturbed environment, which can weaken estimates of selection strength for statistical reasons. “Biologists know that many species who do poorly in human-impacted environments often go extinct in these environments, a phenomenon known as local extinction, says Fugère.

Rates of local extinction have never been higher, yet no species included in our database became locally extinct. So part of the explanation for our main conclusion is that researchers might be studying species that fare relatively better in such environments than the average species on Earth because one can only study selection in species that survive in impacted environments.”

Fugère and Hendry hope that their unexpected result will guide future studies of natural selection and help us better understand evolutionary impacts of environmental changes caused by humans.

Source: McGill University [October 12, 2018]



Does climate vary more from century to century when it is warmer?

Century-scale climate variability was enhanced when the Earth was warmer during the Last Interglacial period (129-116 thousand years ago) compared to the current interglacial (the last 11,700 years), according to a new UCL-led study.

Does climate vary more from century to century when it is warmer?
Credit: Pixabay

The findings, published in Nature Communications and funded by the Natural Environment Research Council (NERC) and the Australian Research Council (ARC), reveal that the Last Interglacial period was punctuated by a series of century-scale arid events in southern Europe and cold water-mass expansions in the North Atlantic.

Assessing natural climate variability under relatively warm conditions is crucial to inform projections under future carbon emission scenarios. Professor Chronis Tzedakis (UCL Geography), study lead author, said: “The Last Interglacial is particularly relevant because it provides insights into climate processes during a period of excess warmth.”

The Last Interglacial period contained an interval of intense Arctic warming, with surface air temperatures estimated at 3-11°C above pre-industrial, comparable to high-latitude warming scenarios for the end of this century.

Global sea-level during the Last Interglacial is estimated to have been ~6-9 m above present, with 0.6-3.5 m derived from melting of the Greenland Ice Sheet.

Previously, several North Atlantic and European records have detected century-scale changes in temperature and precipitation within the Last Interglacial, but there has been considerable uncertainty over the timing, extent and origin of these climate oscillations.

This new study by international researchers from twelve institutions used marine and terrestrial geological archives, coupled with climate model experiments, to create the most detailed timeline of ocean and atmosphere changes in the North Atlantic and southern Europe during the Last Interglacial.

To address the uncertainties in comparing records from different environments, researchers produced a “stratigraphic ‘rosetta stone’ by analysing different fossils from the same sediment samples in a marine core off Lisbon,” said Dr. Luke Skinner (Cambridge University) who led the palaeoceanographic analyses.

“The marine core also contained pollen transported from the Tagus river into the deep sea, thus enabling a direct comparison of vegetation and North Atlantic ocean changes,” said Dr. Vasiliki Margari (UCL Geography), who undertook the pollen analysis.

Changes in vegetation, primarily caused by variations in the amount of rainfall, were then linked to changes in the chemical signature of rainfall recorded in stalagmites from Corchia Cave in northern Italy.

“The Corchia record is particularly important because it is supported by very detailed radiometric dating using the decay of uranium isotopes, producing one of the best chronologies for this period available,” said Dr. Russell Drysdale (University of Melbourne), who led the team studying the Italian cave.

Climate model experiments, undertaken by Dr. Laurie Menviel and Dr. Andrea Taschetto of the University of New South Wales Sydney, revealed that the spatial fingerprint of these changes was consistent with disruptions of the Atlantic meridional overturning circulation.

Greenland ice-melt and runoff as a result of strong high-latitude warming during the Last Interglacial may have contributed to the weakening of the Atlantic meridional overturning circulation and to the observed climate changes.

“Although not a strict analogue for future anthropogenically-driven changes, the profile of the Last Interglacial that emerges is one of enhanced century-scale climate instability, with implications for ice-sheet and ocean dynamics,” said Professor Tzedakis.

“Future research efforts should focus on constraining further the extent of melting and runoff from the Greenland ice-sheet and its effects on ocean circulation during the Last Interglacial.”

Source: University College London [October 12, 2018]




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