суббота, 27 октября 2018 г.

Tracing the evolutionary origins of fish to shallow ocean waters

The first vertebrates on Earth were fish, and scientists believe they first appeared around 480 million years ago. But fossil records from this time are spotty, with only small fragments identified. By 420 million years ago, however, the fossil record blossoms, with a huge variety of fish species present en masse.











Tracing the evolutionary origins of fish to shallow ocean waters
Bothriolepis, an armored, bottom-dwelling placoderm related to some of the earliest jawed vertebrates
 to appear in the record, lived mostly at the coasts [Credit: Nobumichi Tamura]

“It’s been this ongoing question of, well, where were they?” says Lauren Sallan, a paleobiologist at the University of Pennsylvania. “Where were they hiding? What were their environmental origins?”


Sallan Ivan J. Sansom of the University of Birmingham and colleagues are the first to present a wealth of evidence to answer that question in a report out this week in the journal Science.


And the answer, it seems, is near shore, the areas often describe as the intertidal zone, or shallow lagoons.


“In modern conceptions, we see that coral reefs are so important for fish biodiversity, so we assume there’s an ancient link between fishes and reefs going back to the beginning,” says Sallan. “But decades of searching in places like the Cincinnati Arch have come up empty.”


“Instead, our work shows that almost every major vertebrate division, from the earliest armored jawless fish all the way up through sharks and our own ancestors, all started out right near the beach, far inshore of the reef. Even as older groups spread out, newer groups were also appearing at the shoreline.”


The findings help explain important features of the fossil record, such as why so few early fish fossils are found intact; the wave action of the shallow ocean area likely blasted them into tiny fragments. It also helps scientists make sense of the fact that, over evolutionary time, many fish groups moved from ocean water to freshwater with some becoming freshwater fish while others evolved into the earliest tetrapods, land-dwelling vertebrates.











Tracing the evolutionary origins of fish to shallow ocean waters
Sacabambaspis, a 460 million year old jawless relative of modern jawed fishes, swims
in the shallow coastal waters of modern day Bolivia [Credit: Nobumichi Tamura]

“They often went to freshwater before the reefs, which is almost an independent line of evidence that they would have had to have been close to shore before doing so,” Sallan says.


Exactly where vertebrates originated and diversified has been a hotly debated subject in paleontology. Certain groups of fossils from this key period in the middle Paleozoic Era told one story–perhaps a freshwater site of origin–while other groups may point to a birthplace in the open ocean, and still others popped up in other habitat types. Further complicating matters, the origin story of invertebrate biodiversity seem settled: They diversified around coral reefs, their descendants subsequently striking out to inhabit shallower or deeper waters.


Sallan, Sansom, and colleagues decided to investigate the question for vertebrates using a big-data approach.


“The nice thing about the fossil record is that we often find fishes in the context of where they live,” Sallan says. “The rock that holds them tells us what their environment looked like, whether it was reef, shallow water, deep water, a riverbed, or a lake.”


Bringing that environmental context together with what was already known about the family tree relationships of vertebrates from the middle Paleozoic, 480 to 360 million years ago, the researchers created a database that involved 2,728 early records for jawed and jawless fishes.


“It’s a really huge new dataset,” says Sallan.











Tracing the evolutionary origins of fish to shallow ocean waters
Pituriaspis, a member of rare group of 410 million year old jawless fishes from Australia, meets a mate along the shoreline. Research by the University of Pennsylvania’s Lauren Sallan and colleagues found that such groups diversified
in shallow ocean waters before spreading out to other habitat types [Credit: Nobumichi Tamura]

The team was then able to reconstruct the missing information in the fossil record using mathematical modeling, allowing them to make informed predictions about the habitat type in which the earliest ancestors of various vertebrate groups emerged.


“For vertebrates, we find that they’re originating in this unexpected, really restricted shallow area of the oceans,” Sallan says. “And they stay in this limited area for a long time after they emerge.”


As they remained in the shallows, however, they gained a variety of adaptations that enabled them to compete with the others in a shared habitat. The researchers noted that many groups acquired traits that made them well-suited for life either as bottom-dwellers, or for a free-swimming ecology out in the ocean’s deeper waters.


A similar divergence has been seen in modern fish, such as sticklebacks, which evolved a bottom-dwelling and a free-swimming form from common ancestors in more recent times.


No one has done a similarly comprehensive study on living vertebrate species, however. “One of the things we want to know is whether these shallow waters are still the biological pump that is feeding the reef,” Sallan says. “Where is the current site of innovation?”


If that were the case, there may be some small consolation in the face of mass reef die-offs around the world; maybe shallow waters will continue to be the cradle of diversification for fish, allowing biodiversity to persist despite a paucity of reef habitat.


Source: University of Pennsylvania [October 25, 2018]



TANN



Archive


Byzantine-era fountain, 1,000-year-old skeleton found in Istanbul

The archaeological excavation carried out as part of the restoration works in Istanbul’s landmark Haydarpaşa Train Station continues to recover precious historical artefacts that potentially shed light on the city’s Byzantine history.











Byzantine-era fountain, 1,000-year-old skeleton found in Istanbul
Credit: AA

A nearly-intact skeleton wearing what is described as “a scented necklace, believed to be some 1,000 years old”, was found Thursday, the latest discovery at the site.
Three museum experts, 18 archaeologists, one restorer, one photographer and nearly 400 workers resumed efforts at the Haydarpaşa restoration site on May 11.


The excavation recovered dozens of remains of graves, in addition to some 2,000 gold and silver coins and ornaments. Some coins date back to 6th century AD and bear the sign of Justinian I, while some others of Constantine III from the 7th century.











Byzantine-era fountain, 1,000-year-old skeleton found in Istanbul
Credit: AA

Another surprising discovery was a Byzantine-era fountain recovered in working condition, the only one of its kind in Istanbul. The water flowing from the fountain is fed by water channels also recovered during the excavation.
Archaeologists said that the water is of drinking quality, attesting to the utmost care given in the original architectural with enabled the fountain and its channels to endure centuries and heavy layers of construction in surrounding areas.


In the area where train platforms are located, a podium was found which is believed to date back to the Hellenistic period and was constructed with iron clasps and quadrangle blocks of stones. Just north of the platforms, a large wall was also found.











Byzantine-era fountain, 1,000-year-old skeleton found in Istanbul
Credit: AA

The exact construction period of the three-metre-wide wall, which intermittently spans 100 metres, is yet to be determined.
Archaeologists believe that the wall, dating back some 2,000 years, is either the extension of the city walls of the ancient city of Chalcedon or the breakwater of its port.


A mid-Byzantine era ceramics kiln was also found in digs near the İbrahimağa neighbourhood.


Source: Daily Sabah [October 25, 2018]



TANN



Archive


Dry Danube reveals hidden treasure in Hungary

A treasure trove of some 2,000 gold and silver coins has been found on the Danube riverbed in Hungary thanks to an exceptionally low water level, archaeologists said on Thursday.











Dry Danube reveals hidden treasure in Hungary
Hungarian archaeologists inspect the site where they found coins from the 16th-17th centuries and special
weapons on the banks of the Danube river due to its low water level [Credit: Ferenic Isza/AFP]

“Around 2,000 coins have been found, as well as arms, pikes, cannon balls and swords,” Katalin Kovacs, an archaeologist with the Ferenczy Museum Center, told the MTI agency.
The discovery was made this week where the river passes by the town of Erd, to the south of Budapest.











Dry Danube reveals hidden treasure in Hungary
Researchers from the Ferenczy Museum Centre from Szentendre have found the
 sensational treasures in the past few days [Credit: Ferenic Isza/AFP]

Archaeologists are working frantically, assisted by divers and drones, to extract what they can from the site before a rise in river levels expected this weekend.
Like other rivers across Europe, the Danube is in some places at a historically low level after a long period of dry weather. In Budapest it is running at a mere 38cm, which has affected shipping traffic.











Dry Danube reveals hidden treasure in Hungary
According to archaeologists working on site, the treasure comes from a cargo of a commercial
ship that probably sank in the 18th century [Credit: Ferenic Isza/AFP]

The treasure, which includes ducats and pennies, was found amid the wreck of a trading boat whose origin is not yet known, archaeologists said.Like many rivers across Europe, the Danube is in some places at a historically low level after a long period of dry weather
“The coins are 90 percent foreign and date from between 1630 and 1743”, archaeologist Balazs Nagy told the Klub radio station, adding that they had been minted in “the Netherlands, in France, Zurich and even the Vatican”.











Dry Danube reveals hidden treasure in Hungary
The water level is exceptionally low at the moment revealing incredibly rare treasures
from the cargo of an unknown commercial ship [Credit: Ferenic Isza/AFP]

The low level of the Danube has already revealed the remains of Budapest’s former Franz Josef bridge, which was destroyed during World War II, as well as an American bomb from the same period.


Source: AFP [October 25, 2018]



TANN



Archive


Over 200 Viking coins found in Danish wetlands

The city of Ribe in west Jutland can not only claim to be Denmark’s oldest town, but it can now boast to be the site of one of the most interesting archaeological finds in Danish history.











Over 200 Viking coins found in Danish wetlands
Treasures in the soil [Credit: Museum of Southwest Jutland]

In a nearby bog, archaeologists have uncovered 248 coins that are believed to have been minted over 1,000 years ago – way back in the early 9th century.
The excavation, which is ongoing, is unique because only ten such coins have been found worldwide until now, according to the curator of the Museum of Southwest Jutland, Claus Feveile.











Over 200 Viking coins found in Danish wetlands
The so-called face/deer money [Credit: Museum of Southwest Jutland]

“This is an exceptional find that means a quantum leap in our understanding of minting. They are Danish coins and clearly minted for the purpose of being implemented in Ribe,” Feveile told DR Nyheder.
“This completely shifts our understanding of how we used to mint and the process of coin production.”











Over 200 Viking coins found in Danish wetlands
With the excavator, the archaeologists scrape off thin layers and the surface is thoroughly
scoured with metal detectors
 [Credit: Museum of Southwest Jutland]

The coins were found in an old bog area, and this has meant that the coins have been preserved to the point where they look almost freshly-minted.


The discovery will assist archaeologists in studying coin dies and learning more about the kingship behind the minting.


The coins will be on display at the Museum of Southwest Jutland from October 29 to November 4.


Source: The Copenhagen Post [October 25, 2018]



TANN



Archive


Tunnel, chamber discovered beneath Mexico’s Pyramid of the Moon

Experts have discovered a tunnel leading to a chamber that was possibly used for funeral rituals beneath the Pyramid of the Moon at the Teotihuacán archaeological site.











Tunnel, chamber discovered beneath Mexico's Pyramid of the Moon
Archaeologists have discovered a new tunnel and a cavity hidden below an ancient pyramid
in Mexico that is believed to have been dedicated to ‘underworld’ Toltec rituals
[Credit: Mauricio Marat/INAH]

A team of researchers from the National Institute of Anthropology and History (INAH) working in collaboration with the Institute of Geophysics at the National Autonomous University (UNAM) made the finds during an electrical resistivity study of the pyramid.


Verónica Ortega, director of the Plaza de la Luna Conservation Project, said it is possible that human remains and artifacts could be found in the 15-metre-diametre chamber.


She explained that archaeologists discovered skeletons with deformed skulls as well as a range of objects made out of green stone within the same pyramid in the 1980s.


“Because of that it’s not hard to think that something similar could be found”, Ortega said.











Tunnel, chamber discovered beneath Mexico's Pyramid of the Moon
To demonstrate the possibilities of the proposed ERT-3D method, 72 electrodes were deployed around the base of the temple
of El Osario (A). The inverted model shows a high resistivity anomaly towards the central part of the WRC (B). This
anomaly can be isolated and a void structure can be observed, corresponding to the mentioned cavity (C). The image
of the WRC, seen from above, defines the dimensions of the structure, and the 3 passages that connect it (D, broken
arrows). The outline of El Osario was placed on top of the resistivity model for a better visualization, as well
as the location of the vertical shaft entrance (E) [Credit: René E. Chávez et al. 2018]

She added that the investigation would help researchers to understand more about ancient rituals at Teotihuacán and the civilization’s relationship with other pre-Hispanic cultures.


“What’s found inside could help to unravel the relationships that this ancient metropolis had with other regions of Mesoamerica,” Ortega said.


At the start of this month, the INAH team carried out a new study that detected the location of the tunnel leading to the chamber.


“The tunnel is towards the south of the Plaza de la Luna [Plaza of the Moon] but it’s probable that there is another entrance [to the chamber] towards the eastern side. Consequently, getting a complete radiography is fundamental to finding out where it can be accessed from,” Ortega said.


The Pyramid of the Moon is the only structure at Teotihuacán that directly faces the Calzada de los Muertos, or Avenue of the Dead. It is believed to have been enlarged seven times since it was first built.


The findings are published in Scientific Reports.


Source: Mexico News Daily [October 25, 2018]



TANN



Archive


3,000-year-old burials found in Cusco

Experts from the Decentralized Culture Directorate of Cusco (DDCC) have unearthed two human burials — dating back 3,000 years — in Marcavalle archaeological area comprised in South-Andean Cusco region.











3,000-year-old burials found in Cusco
Credit: Andina/Percy Hurtado Santillán

According to research project director Luz Marina Monrroy, the first one belongs to a person under the age of 20.
The bent body features cephalic modifications and was surrounded by a stone structure.











3,000-year-old burials found in Cusco
Credit: Andina/Percy Hurtado Santillán

Furthermore, a perforated golden circular sheet — for ornamental purposes — was linked to the skull.


The complete skeleton of a young individual — lying on its side — was discovered in the second burial, located a few meters from the first one.











3,000-year-old burials found in Cusco
Credit: Andina/Percy Hurtado Santillán

Diverse cultural items —including obsidian pieces— were found close to it.
“These findings belong to the formative period; that means, approximately 1,000 BC, which confirms Marcavalle holds the first human burials unearthed in Cusco’s Valley (…),” the archeologist expressed.











3,000-year-old burials found in Cusco
Credit: Andina/Percy Hurtado Santillán

Among the five excavation sites in the area, DDCC researchers have also discovered the burial of a South American camelid —suspected to be part of a sacrifice— in a circular well, the oldest one found in Cusco.


Likewise, evidence of a lithic workshop has been discovered, as well as architectural segments composed of chambers, stone walls, and remains of an elevated platform.











3,000-year-old burials found in Cusco
Credit: Andina/Percy Hurtado Santillán

Fragments of decorated and painted ceramics, with incisions showing human faces, bone instruments, carbonized residues of farming products, and stone mortars were also seen at the archaeological site.
The project has been scheduled to run thru end-2018, thus researchers will continue to dig in accordance with the inter-institutional agreement signed between the DDCC and Cusco’s Superior Justice Court. Both organizations work together to protect Marcavalle’s cultural heritage.


Source: Andina [October 25, 2018]



TANN



Archive


Heat Wave Although we can see some of the blood vessels…


Heat Wave


Although we can see some of the blood vessels under our skin, many are buried deep. Here a technique called photoacoustic tomography reveals the hidden network of arteries and veins in an adult’s palm. Harmless laser pulses turn into tiny puffs of heat after hitting chemicals in the blood –helping to produce these maps of circulation. On the right, artificial colours pick out deeper vessels in red and yellow. These are mostly arteries, with veins lying nearer the surface of the skin in blue and green. After testing on healthy subjects, the technique may be applied to investigate conditions like varicose veins – looking for changes in the bends and twists of vessels – or to spot angiogenesis, the formation of new vessels common in breast cancer; guiding diagnosis, treatment and recovery.


Written by John Ankers



You can also follow BPoD on Instagram, Twitter and Facebook


Archive link


Light Installations in Gop Cave, a Mesolithic and Neolithic site in North Wales,...





Light Installations in Gop Cave, a Mesolithic and Neolithic site in North Wales, 27.10.18.


Source link


Stratocumulus Cirrocumulus clouds кучевые облака TimeLapse

Stratocumulus Cirrocumulus clouds кучевые облака TimeLapse
Source Stratocumulus Cirrocumulus clouds кучевые облака TimeLapse by AncientWanderer
 Grey or whitish, or both grey and whitish, patch, sheet or layer of cloud that almost always has dark parts, composed of tessellations, rounded masses, rolls, etc. Cirrocumulus are a relatively rare cloud forming ripples which may resemble honeycomb or the scales of fish, giving rise to the phrase 'mackerel skies'. Height of base: 20,000 - 40,000 ft
 Shape Layers or patches of cells Latin: cirrus - lock or tuft of hair cumulus - heap

Слоисто-кучевые облака (лат. Stratocumulus, Sc) — крупные серые гряды пластин или хлопьев, разделённые просветами, либо сливающиеся в сплошной покров. Образуются на высоте 0,6—1,5 км. Состоят в основном из мелких капелек воды радиусом 5—7 мкм с колебаниями от 1 до 60 мкм, зимой переохлаждённых. Из большинства разновидностей слоисто-кучевых облаков осадки, как правило, не выпадают. Из непросвечивающих слоисто-кучевых (Sc op.) может выпасть слабый дождь или редкий снег.

 Высококучевые облака (лат. Altocumulus, Ac) — белые, сероватые или синеватые облака в виде гряд, состоящих из пластин или хлопьев, которые могут сливаться в сплошной покров. Образуются на высоте от 2 до 6 километров. Состоят в основном из переохлажденных капелек воды радиусом 5—7 мкм с колебаниями от 3 до 24 мкм. Сквозь тонкие края высоко-кучевых облаков просвечивают Солнце и Луна, вокруг них часто наблюдаются венцы. Сквозь уплотнения просветов нет или они очень слабые. Из высоко-кучевых облаков могут выпадать осадки в виде отдельных капель дождя или снежинок.
  Слоисто-кучевые облака (лат. Stratocumulus, Sc) — крупные серые гряды пластин или хлопьев, разделённые просветами, либо сливающиеся в сплошной покров. Образуются на высоте 0,6—1,5 км. Состоят в основном из мелких капелек воды радиусом 5—7 мкм с колебаниями от 1 до 60 мкм, зимой переохлаждённых. Из большинства разновидностей слоисто-кучевых облаков осадки, как правило, не выпадают. Из непросвечивающих слоисто-кучевых (Sc op.) может выпасть слабый дождь или редкий снег.Слоисто-кучевые облака (лат. Stratocumulus, Sc) — крупные серые гряды пластин или хлопьев, разделённые просветами, либо сливающиеся в сплошной покров. Образуются на высоте 0,6—1,5 км. Состоят в основном из мелких капелек воды радиусом 5—7 мкм с колебаниями от 1 до 60 мкм, зимой переохлаждённых. Из большинства разновидностей слоисто-кучевых облаков осадки, как правило, не выпадают. Из непросвечивающих слоисто-кучевых (Sc op.) может выпасть слабый дождь или редкий снег.Слоисто-кучевые облака (лат. Stratocumulus, Sc) — крупные серые гряды пластин или хлопьев, разделённые просветами, либо сливающиеся в сплошной покров. Образуются на высоте 0,6—1,5 км. Состоят в основном из мелких капелек воды радиусом 5—7 мкм с колебаниями от 1 до 60 мкм, зимой переохлаждённых. Из большинства разновидностей слоисто-кучевых облаков осадки, как правило, не выпадают. Из непросвечивающих слоисто-кучевых (Sc op.) может выпасть слабый дождь или редкий снег.Слоисто-кучевые облака (лат. Stratocumulus, Sc) — крупные серые гряды пластин или хлопьев, разделённые просветами, либо сливающиеся в сплошной покров. Образуются на высоте 0,6—1,5 км. Состоят в основном из мелких капелек воды радиусом 5—7 мкм с колебаниями от 1 до 60 мкм, зимой переохлаждённых. Из большинства разновидностей слоисто-кучевых облаков осадки, как правило, не выпадают. Из непросвечивающих слоисто-кучевых (Sc op.) может выпасть слабый дождь или редкий снег. Высококучевые облака (лат. Altocumulus, Ac) — белые, сероватые или синеватые облака в виде гряд, состоящих из пластин или хлопьев, которые могут сливаться в сплошной покров. Образуются на высоте от 2 до 6 километров. Состоят в основном из переохлажденных капелек воды радиусом 5—7 мкм с колебаниями от 3 до 24 мкм. Сквозь тонкие края высоко-кучевых облаков просвечивают Солнце и Луна, вокруг них часто наблюдаются венцы. Сквозь уплотнения просветов нет или они очень слабые. Из высоко-кучевых облаков могут выпадать осадки в виде отдельных капель дождя или снежинок. Высококучевые облака (лат. Altocumulus, Ac) — белые, сероватые или синеватые облака в виде гряд, состоящих из пластин или хлопьев, которые могут сливаться в сплошной покров. Образуются на высоте от 2 до 6 километров. Состоят в основном из переохлажденных капелек воды радиусом 5—7 мкм с колебаниями от 3 до 24 мкм. Сквозь тонкие края высоко-кучевых облаков просвечивают Солнце и Луна, вокруг них часто наблюдаются венцы. Сквозь уплотнения просветов нет или они очень слабые. Из высоко-кучевых облаков могут выпадать осадки в виде отдельных капель дождя или снежинок. Высококучевые облака (лат. Altocumulus, Ac) — белые, сероватые или синеватые облака в виде гряд, состоящих из пластин или хлопьев, которые могут сливаться в сплошной покров. Образуются на высоте от 2 до 6 километров. Состоят в основном из переохлажденных капелек воды радиусом 5—7 мкм с колебаниями от 3 до 24 мкм. Сквозь тонкие края высоко-кучевых облаков просвечивают Солнце и Луна, вокруг них часто наблюдаются венцы. Сквозь уплотнения просветов нет или они очень слабые. Из высоко-кучевых облаков могут выпадать осадки в виде отдельных капель дождя или снежинок. Grey or whitish, or both grey and whitish, patch, sheet or layer of cloud that almost always has dark parts, composed of tessellations, rounded masses, rolls, etc. Cirrocumulus are a relatively rare cloud forming ripples which may resemble honeycomb or the scales of fish, giving rise to the phrase 'mackerel skies'. Height of base: 20,000 - 40,000 ft Shape: Layers or patches of cells Latin: cirrus - lock or tuft of hair cumulus - heap Grey or whitish, or both grey and whitish, patch, sheet or layer of cloud that almost always has dark parts, composed of tessellations, rounded masses, rolls, etc. Cirrocumulus are a relatively rare cloud forming ripples which may resemble honeycomb or the scales of fish, giving rise to the phrase 'mackerel skies'. Height of base: 20,000 - 40,000 ft Shape: Layers or patches of cells Latin: cirrus - lock or tuft of hair cumulus - heap Grey or whitish, or both grey and whitish, patch, sheet or layer of cloud that almost always has dark parts, composed of tessellations, rounded masses, rolls, etc. Cirrocumulus are a relatively rare cloud forming ripples which may resemble honeycomb or the scales of fish, giving rise to the phrase 'mackerel skies'. Height of base: 20,000 - 40,000 ft Shape: Layers or patches of cells Latin: cirrus - lock or tuft of hair cumulus - heap Grey or whitish, or both grey and whitish, patch, sheet or layer of cloud that almost always has dark parts, composed of tessellations, rounded masses, rolls, etc. Cirrocumulus are a relatively rare cloud forming ripples which may resemble honeycomb or the scales of fish, giving rise to the phrase 'mackerel skies'. Height of base: 20,000 - 40,000 ft Shape: Layers or patches of cells Latin: cirrus - lock or tuft of hair cumulus - heap Grey or whitish, or both grey and whitish, patch, sheet or layer of cloud that almost always has dark parts, composed of tessellations, rounded masses, rolls, etc. Cirrocumulus are a relatively rare cloud forming ripples which may resemble honeycomb or the scales of fish, giving rise to the phrase 'mackerel skies'. Height of base: 20,000 - 40,000 ft Shape: Layers or patches of cells Latin: cirrus - lock or tuft of hair cumulus - heap Grey or whitish, or both grey and whitish, patch, sheet or layer of cloud that almost always has dark parts, composed of tessellations, rounded masses, rolls, etc. Cirrocumulus are a relatively rare cloud forming ripples which may resemble honeycomb or the scales of fish, giving rise to the phrase 'mackerel skies'. Height of base: 20,000 - 40,000 ft Shape: Layers or patches of cells Latin: cirrus - lock or tuft of hair cumulus - heap

Coyamito Agate Pseudomorph aka pretty rock. | #Geology…


Coyamito Agate Pseudomorph aka pretty rock. | #Geology #GeologyPage #Agate #Mineral


Photo Copyright © onebrightcrew/flickr


Geology Page

www.geologypage.com

https://www.instagram.com/p/BpbaUnTl9hs/?utm_source=ig_tumblr_share&igshid=1evrtpvgd3juc


2018 October 27 Airglow Borealis Image Credit & Copyright:…


2018 October 27


Airglow Borealis
Image Credit & Copyright: Yuri Beletsky (Carnegie Las Campanas Observatory, TWAN)


Explanation: The best known asterism in northern skies hangs over the Canadian Rockies in this mountain and night skyscape taken last week from Banff National Park. But most remarkable is the amazing greenish airglow. With airglow visible to the eye, but not in color, the scene was captured in two exposures with a single camera, one exposure made while tracking the stars and one fixed to a tripod. Airglow emission is predominately from atmospheric oxygen atoms at extremely low densities. Commonly recorded in color by sensitive digital cameras the eerie, diffuse light is seen here in waves across the northern night. Originating at an altitude similar to aurorae, the luminous airglow is due to chemiluminescence, the production of light through chemical excitation and radiative decay. Energy for the chemical excitation is provided during daytime by the Sun’s extreme ultraviolet radiation. Unlike aurorae which are limited to high latitudes, airglow can be found around the globe.


∞ Source: apod.nasa.gov/apod/ap181027.html


HiPOD (26 October 2018): Like a Lonely, Little Isle   – This…



HiPOD (26 October 2018): Like a Lonely, Little Isle


   – This image is in Mamers Valles, which is a winding canyon in the north of Mars, about 1000 kilometers in length. It likely formed about 3.8 billion years ago. (297 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


Forming Mercury by Giant Impacts


Movie of a Case-1 collision: the proto-Mercury of 2.7 M_☿ collides with the impactor of 1.125 M_☿ at an impact angle of b=0.2 and v=18 km/s. In the right panel, we zoom on the largest fragment of 0.99 M_☿ and an iron-to-rock ratio of 0.6.

The smallest planet in our Solar System has a large iron core. How come? According to the most popular theory, Mercury lost big parts of its rocky mantle in a collision. Alice Chau and her colleagues at the University of Zürich simulated different scenarios with a super computer. Their result: Forming Mercury by giant impacts is feasible but difficult.


Compared to Earth, Venus or Mars, Mercury is much more metallic. It has a large iron core and only a thin rocky mantle. This mysterious nature has puzzled researchers for decades. “We think that Mercury might have formed in a similar way as the other planets, and therefore initially had a core which weighed one third of the planet’s mass, but lost most of its mantle”, explains Alice Chau, PhD student and associate of PlanetS at the University of Zürich. But how this loss came about is still being debated.


In 1988, Willy Benz, now director of the NCCR PlanetS, and colleagues suggested that this was due to the blasting off of the mantle during a giant impact and simulated such a process with computer calculations which were refined in 2007. “However, the exact conditions that lead to Mercury’s formation via a giant impact are still unknown,” says Chau. Therefore, together with her colleagues at the Institute for Computational Science she decided to investigate the giant impact hypothesis based on simulations performed with one of the most powerful supercomputers in Europe. The machine called “Piz Daint” named after a prominent peak in Grisons is located at the Swiss National Supercomputing Centre (CSCS) in Lugano.


“We investigated three different scenarios,” explains Chau. In “Case-1” the proto-Mercury is hit by a smaller body as in the simulations calculated by Benz et al. in 2007. In “Case-2” Mercury is actually the impactor and collides with a larger body which no longer resides in the Solar System. This is called the hit-and-run scenario. In the third case, Mercury is hit by multiple impactors. “We found that it is possible to form Mercury in all these scenarios but each of them requires rather specific conditions,” summarizes Chau.


Multiple impacts more probable

For instance, in a single violent collision the impact angle and velocity have to be highly tuned to reproduce Mercury’s mass and iron-to-rock ratio. In addition, it is still an open question whether datacollected by the NASA spacecraft Messenger are consistent with a single giant impact. New observations by Europe’s BepiColombo could solve this problem, once the spacecraft will have arrived at Mercury in 2025. “It is therefore possible, and maybe even more probable, that Mercury formed as a result of multiple impacts,” the team writes in its paper published in the Astrophysical Journal.


The fact that it seems difficult to form Mercury maybe disappointing, but it also has something to offer: “It is consistent with the fact that we observed only very few exoplanets that have similar average density as Mercury among the few thousands we already know,” says Chau: “What will be very interesting is if we discover more of these planets to investigate if they have a common formation mechanism with Mercury, and maybe they will help us to better understand the origin our own Mercury.“


Alice Chau, Christian Reinhardt, Ravit Helled, and Joachim Stadel: Forming Mercury by Giant Impacts, The Astrophysical Journal, Volume 865, Number 1,


DOI: https://doi.org/10.3847/1538-4357/aad8b0






Archive link


Do mussels reveal the fate of the oceans?

More than 10 million tons of plastic debris enter the oceans every year and are found in nearly every oceanic layer. They start out as large floating items and eventually break down into much smaller pieces called microplastics. These particles are pervasive and have been found in the digestive tracts of more than 100 different species, posing physical, chemical and even potential biological harm to these animals. Mussels and other bivalves like oysters and clams are eaten whole without removal of the gastrointestinal tract and therefore represent a pathway for microplastics to enter the human food chain.











Do mussels reveal the fate of the oceans?
For the study, the researchers collected marine aggregates and blue mussels at Avery Point in Connecticut and used
microscopy and microspectrometry to measure the spectra of these microscopic samples [Credit: Evan Ward/
Meghan Danley/University of Connecticut, and Shiye Zhao/FAU-Harbor Branch]

Contrary to prior research, a first-of-its-kind study from a team of scientists suggests that mussels are not a robust indicator of microplastics in the marine environment because of their inherent ability to selectively feed, making them very picky eaters. Instead, marine aggregates, also referred to as “marine snow,” have much more to say about the fate of microplastics in the environment.


Marine aggregates are a predominant form of sinking particulate carbon in the marine water column and form the basis of the food chain in the ocean. These aggregates also represent a mechanism for transporting microplastics to the sea floor. The study demonstrates that they play an important role in removing microplastics from the ocean surface, vertically transferring them through the water column, and facilitating their transfer to marine food webs.


Using a powerful tool called spectroscopy, researchers from Florida Atlantic University, East China Normal University, Woods Hole Oceanographic Institution, the University of Connecticut, and the University of New England, are the first to identify a connection, under field conditions, between microplastics within marine aggregates and mussels (Mytulis edulis). Results of the study, published in the journal Environmental Science & Technology, have important implications for the fate of plastic particles in marine environments.


“We suspected that suspension-feeding bivalves like mussels would particularly be impacted by plastic-laden marine aggregates,” said Tracy J. Mincer, Ph.D., co-author and a research professor at FAU’s Harbor Branch Oceanographic Institute and FAU’s Harriet L. Wilkes Honors College. “We wanted to better understand the link between marine aggregates, microplastics and marine animals, especially bivalves, in the environment.”


For the study, the researchers collected marine aggregates and blue mussels at Avery Point in Connecticut and used microscopy and microspectrometry to measure the spectra of these microscopic samples. They found that 73 percent of the marine aggregates they sampled contained plastic particles. More than 90 percent of these microplastics measured less than 1 millimeter.


In the mussels, the researchers detected microplastics in the biodeposits or digestive gland/gut of nearly all of the mussels they collected from the Avery Point dock. More than 40 percent of the microplastic particles were either rejected in the mussels’ pseudofeces or egested (discharging undigested material) in feces. Normally, mussels can digest their food within a matter of minutes. In contrast, the plastic particles passed to the digestive diverticula of the mussels took days to digest.


The characteristics of microplastics in the marine aggregates and mussels were similar, which provided further evidence of marine aggregates’ role in the trophic transfer of plastic particles to bottom suspension-feeders.


The uniformity of microplastic sizes and shapes identified within the mussels indicated that selective ingestion of certain types of plastics occurred. The mussels preferentially ingested particles of a smaller size and a relatively larger shape factor.


“The good news is that mussels are picky eaters and have well-developed mechanisms for particle discrimination,” said Mincer. “They sort particles based on physical features like size, shape, flexibility and density as well as chemical and nutritional properties. Particle selection is one strategy that they use to enhance their diet quality and optimize energy intake.”


The chemical composition from these marine aggregates were diverse and included a broad range of domestic and industrial uses. Polypropylene, polyester and cellulose acetate, commonly used in cigarette filters, hygiene products, and clothing, made up nearly 76.3 percent of all plastic particles identified in the sampled marine aggregates. Cellulose acetate is primarily introduced into marine environments via sewage discharge, and cigarette butts are a major coastal ocean input mechanism as well.


An unexpected finding from the study was that fragmented plastics were the predominant type of synthetic particles identified in the marine aggregates and accounted for 65.9 percent of all microplastics.


The researchers compared the abundances of plastic particles in the marine aggregates with other reports worldwide. They also found that the concentration of microplastics in the mussels they sampled was about three times lower than those found in wild mussels from China’s coastal waters.


Author: Gisele Galoustian | Source: Florida Atlantic University [October 23, 2018]



TANN



Archive


Wildlife on the highway to hell: Roadkill in the largest wetland, Pantanal region, Brazil

Having systematically monitored wild animals killed on the Brazilian federal highway BR-262, which passes through the Pantanal region, a research team from the Federal University of Mato Grosso do Sul, Brazil, published their data concerning birds and reptiles in the open access journal Check List.











Wildlife on the highway to hell: Roadkill in the largest wetland, Pantanal region, Brazil
These are roadkills on the BR-262 highway, Pantanal region, Brazil
[Credit: Ricardo Fraga & Wagner Fischer]

Apart from information crucial for future conservation activities, the paper provides new and unexpected roadkill records, including the Black-and-white hawk-eagle.
Authored by Wagner Fischer and his colleagues Raquel Faria de Godoi and Antonio Conceição Paranhos Filho, the article is part of the first dataset of vertebrate mortality in the region. A separate paper of theirs is planned to present the data concerning mammals gathered during the same survey, which took place between 1996 and 2000.


Having mapped bird and reptile roadkill on the highway between the cities of Campo Grande and Corumbá in the Brazilian savannah, the team reports a total of 930 animals representing 29 reptile and 47 bird species. In addition, the data provide the first regional geographic record of the colubrid snake Hydrodynastes bicinctus.











Wildlife on the highway to hell: Roadkill in the largest wetland, Pantanal region, Brazil
This is an adult individual of Erythrolamprus aesculapii captured in roadside habitats of BR-262
[Credit: Michel Passos]

The researchers conclude that the species richness observed in the road-killed animals clearly confirms earlier concerns about wildlife-vehicle collisions in the Pantanal region. Such accidents lead to long-term and chronic impact on both wildlife and road safety.
“Mitigation of wildlife-vehicle collisions on this road continues to claim urgency for biodiversity conservation and for human and animal safety and care,” say the authors.


“For managers, the main goal should be to determine target species of greatest concern, focusing on those vulnerable to local extinction or those which represent major risks of serious accidents.”











Wildlife on the highway to hell: Roadkill in the largest wetland, Pantanal region, Brazil
This is an adult individual of Xenodon matogrossensis captured in roadside habitats of BR-262
[Credit: Cyntia Santos]

In the past, the team’s dataset had already been used as a guide to road fauna management. In particular, it was used by government road managers when planning animal overpassess and underpassess equipped with roadside fences as part of the long-term project Programa Estrada Viva: BR-262. So far, however, only some of the less efficient safety methods, such as road signs and lowered speed limits, have been applied at the most critical points.
Over the past several years, a few independent studies have been conducted to monitor roadkill in a similar manner. Two of them (2010 and 2017) looked into mammal-vehicle collisions, while the third recorded reptiles and birds as well. All of them serve to demonstrate that BR-262 continues to be a major cause for the regional wildlife mortality, which in turn increases the risks of serious accidents.


“BR-262 keeps its inglorious fame as a highway to hell for human and wild lives,” points out lead author Wagner Fischer.


Source: Pensoft Publishers [October 23, 2018]



TANN



Archive


Featured

UFO sighting in Odessa UA НЛО шар плазмы UFO sighting in Odessa UA, white orb An unusual-looking object appeared suddenly in the sky at...

Popular