Device could open up new areas of research on materials and biological samples at tiny scales.


CAMBRIDGE, MA Researchers at MIT, working with partners at NASA, have developed a new concept for a microscope that would use neutrons — subatomic particles with no electrical charge — instead of beams of light or electrons to create high-resolution images.

Among other features, neutron-based instruments have the ability to probe inside metal objects — such as fuel cells, batteries, and engines, even when in use — to learn details of their internal structure. Neutron instruments are also uniquely sensitive to magnetic properties and to lighter elements that are important in biological materials.

The new concept has been outlined in a series of research papers this year, including one published this week in Nature Communications by MIT postdoc Dazhi Liu, research scientist Boris Khaykovich, professor David Moncton, and four others.

Moncton, an adjunct professor of physics and director of MIT’s Nuclear Reactor Laboratory, says that Khaykovich first proposed the idea of adapting a 60-year-old concept for a way of focusing X-rays using mirrors to the challenge of building a high-performing neutron microscope. Until now, most neutron instruments have been akin to pinhole cameras: crude imaging systems that simply let light through a tiny opening. Without efficient optical components, such devices produce weak images with poor resolution.

Beyond the pinhole

“For neutrons, there have been no high-quality focusing devices,” Moncton says. “Essentially all of the neutron instruments developed over a half-century are effectively pinhole cameras.” But with this new advance, he says, “We are turning the field of neutron imaging from the era of pinhole cameras to an era of genuine optics.”

“The new mirror device acts like the image-forming lens of an optical microscope,” Liu adds.

Because neutrons interact only minimally with matter, it’s difficult to focus beams of them to create a telescope or microscope. But a basic concept was proposed, for X-rays, by Hans Wolter in 1952 and later developed, under the auspices of NASA, for telescopes such as the orbiting Chandra X-ray Observatory (which was designed and is managed by scientists at MIT). Neutron beams interact weakly, much like X-rays, and can be focused by a similar optical system.

It’s well known that light can be reflected by normally nonreflective surfaces, so long as it strikes that surface at a shallow angle; this is the basic physics of a desert mirage. Using the same principle, mirrors with certain coatings can reflect neutrons at shallow angles.

A sharper, smaller device

The actual instrument uses several reflective cylinders nested one inside the other, so as to increase the surface area available for reflection. The resulting device could improve the performance of existing neutron imaging systems by a factor of about 50, the researchers say — allowing for much sharper images, much smaller instruments, or both.

The team initially designed and optimized the concept digitally, then fabricated a small test instrument as a proof-of-principle and demonstrated its performance using a neutron beam facility at MIT’s Nuclear Reactor Laboratory. Later work, requiring a different spectrum of neutron energies, was carried out at Oak Ridge National Laboratory (ORNL) and at the National Institute of Standards and Technology (NIST).

Such a new instrument could be used to observe and characterize many kinds of materials and biological samples; other nonimaging methods that exploit the scattering of neutrons might benefit as well. Because the neutron beams are relatively low-energy, they are “a much more sensitive scattering probe,” Moncton says, for phenomena such as “how atoms or magnetic moments move in a material.”

The researchers next plan to build an optimized neutron-microscopy system in collaboration with NIST, which already has a major neutron-beam research facility. This new instrument is expected to cost a few million dollars.

Moncton points out that a recent major advance in the field was the construction of a $1.4 billion facility that provides a tenfold increase in neutron flux. “Given the cost of producing the neutron beams, it is essential to equip them with the most efficient optics possible,” he says. 

In addition to the researchers at MIT, the team included Mikhail Gubarev and Brian Ramsey of NASA’s Marshall Space Flight Center and Lee Robertson and Lowell Crow of ORNL. The work was supported by the U.S. Department of Energy.

Drilling cores from Switzerland have revealed the oldest known fossils of direct ancestors of flowering plants. These beautifully preserved 240-million-year-old pollen grains are evidence that flowering plants evolved 100 million years earlier than previously thought, according to Rsearchers from the University of Zurich.

Flowering plants evolved from extinct plants related to conifers, ginkgos, cycads, and seed ferns. The oldest known fossils from flowering plants are pollen grains. These are small, robust and numerous and therefore fossilize more easily than leaves and flowers. An uninterrupted sequence of fossilized pollen from flowers begins in the Early Cretaceous, approximately 140 million years ago, and it is generally assumed that flowering plants first evolved around that time. But the present study documents flowering plant-like pollen that is 100 million years older, implying that flowering plants may have originated in the Early Triassic (between 252 to 247 million years ago) or even earlier.

Many studies have tried to estimate the age of flowering plants from molecular data, but so far no consensus has been reached. Depending on dataset and method, these estimates range from the Triassic to the Cretaceous. Molecular estimates typically need to be “anchored” in fossil evidence, but extremely old fossils were not available for flowering plants. “That is why the present finding of flower-like pollen from the Triassic is significant”, says Prof. Peter Hochuli, University of Zurich.

Peter Hochuli and Susanne Feist-Burkhardt from Paleontological Institute and Museum, University of Zürich, studied two drilling cores from Weiach and Leuggern, northern Switzerland, and found pollen grains that resemble fossil pollen from the earliest known flowering plants. With Confocal Laser Scanning Microscopy, they obtained high-resolution images across three dimensions of six different types of pollen.

In a previous study from 2004, Hochuli and Feist-Burkhardt documented different, but clearly related flowering-plant-like pollen from the Middle Triassic in cores from the Barents Sea, south of Spitsbergen. The samples from the present study were found 3000 km south of the previous site. “We believe that even highly cautious scientists will now be convinced that flowering plants evolved long before the Cretaceous”, say Hochuli.

What might these primitive flowering plants have looked like? In the Middle Triassic, both the Barents Sea and Switzerland lay in the subtropics, but the area of Switzerland was much drier than the region of the Barents Sea. This implies that these plants occurred a broad ecological range. The pollen’s structure suggests that the plants were pollinated by insects: most likely beetles, as bees would not evolve for another 100 million years.

Literature:

Peter A. Hochuli and Susanne Feist-Burkhardt. Angiosperm-like pollen and Afropollis from the Middle Triassic (Anisian) of the Germanic Basin (Northern Switzerland). Journal: Frontiers in Plant Science. DOI: 10.3389/fpls.2013.00344

FOTO SU:   VEDI TU

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The elongated body of some present-day fish evolved in different ways. Paleontologists from the University of Zurich have now discovered a new mode of body elongation based on a discovery in an exceptionally preserved fossilfish from Southern Ticino. In Saurichthys curionii, an early ray-finned fish, the vertebral arches of the axial skeleton doubled, resulting in the elongation of its body and giving it a needlefish-like appearance. The 240-million-year-old fossil find from Switzerland also revealed that this primitive fish was not as flexible as today’s eels, nor could it swim as fast or untiringly as a tuna.

Snake and eel bodies are elongated, slender and flexible in all three dimensions. This striking body plan has evolved many times independently in the more than 500 million years of vertebrate animals history. Based on the current state of knowledge, the extreme elongation of the body axis occurred in one of two ways: either through the elongation of the individual vertebrae of the vertebral column, which thus became longer, or through the development of additional vertebrae and associated muscle segments.
Long body thanks to doubling of the vertebral arches

A team of paleontologists from the University of Zurich headed by Professor Marcelo Sánchez-Villagra now reveal that a third, previously unknown mechanism of axial skeleton elongation characterized the early evolution of fishes, as shown by an exceptionally preserved form. Unlike other known fish with elongate bodies, the vertebral column of Saurichthys curionii does not have one vertebral arch per myomeric segment, but two, which is unique. This resulted in an elongation of the body and gave it an overall elongate appearance. “This evolutionary pattern for body elongation is new,” explains Erin Maxwell, a postdoc from Sánchez-Villagra’s group. “Previously, we only knew about an increase in the number of vertebrae and muscle segments or the elongation of the individual vertebrae.”

The fossils studied come from the Monte San Giorgio find in Ticino, which was declared a world heritage site by UNESCO in 2003. The researchers owe their findings to the fortunate circumstance that not only skeletal parts but also the tendons and tendon attachments surrounding the muscles of the primitive predatory fish had survived intact. Due to the shape and arrangement of the preserved tendons, the scientists are also able to draw conclusions as to the flexibility and swimming ability of the fossilized fish genus. According to Maxwell, Saurichthys curionii was certainly not as flexible as today’s eels and, unlike modern oceanic fishes such as tuna, was probably unable to swim for long distances at high speed. Based upon its appearance and lifestyle, the roughly half-meter-long fish is most comparable to the garfish or needlefish that exist today.
Literature:

Erin E. Maxwell, Heinz Furrer, Marcelo R. Sánchez-Villagra. Exceptional fossil preservation demonstrates a new mode of axial skeleton elongation in early ray-finned fishes. Nature Communications, October 7, 2013. doi: 10.1038/ncomms3570

FOTO CON DIDASCALIA CHE MERITA SU

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Paleoanthropologists from the University of Zurich have uncovered the intact skull of an early Homo individual in Dmanisi, Georgia. This find is forcing a change in perspective in the field of paleoanthropology: human species diversity two million years ago was much smaller than presumed thus far. However, diversity within the «Homo erectus», the first global species of human, was as great as in humans today.

This is the best-preserved fossil find yet from the early era of our genus. The particularly interesting aspect is that it displays a combination of features that were unknown to us before the find. The skull, found in Dmanisi by anthropologists from the University of Zurich as part of a collaboration with colleagues in Georgia funded by the Swiss National Science Foundation, has the largest face, the most massively built jaw and teeth and the smallest brain within the Dmanisi group.

It is the fifth skull to be discovered in Dmanisi. Previously, four equally well-preserved hominid skulls as well as some skeletal parts had been found there. Taken as a whole, the finds show that the first representatives of the genus Homo began to expand from Africa through Eurasia as far back as 1.85 million years ago.
Diversity within a species instead of species diversity

Because the skull is completely intact, it can provide answers to various questions which up until now had offered broad scope for speculation. These relate to none less than the evolutionary beginning of the genus «Homo» in Africa around two million years ago at the beginning of the Ice Age, also referred to as the Pleistocene. Were there several specialized «Homo» species in Africa at the time, at least one of which was able to spread outside of Africa too? Or was there just one single species that was able to cope with a variety of ecosystems? Although the early Homo finds in Africa demonstrate large variation, it has not been possible to decide on answers to these questions in the past. One reason for this relates to the fossils available, as Christoph Zollikofer, anthropologist at the University of Zurich, explains: «Most of these fossils represent single fragmentary finds from multiple points in space and geological time of at least 500,000 years. This ultimately makes it difficult to recognize variation among species in the African fossils as opposed to variation within species».
As many species as there are researchers

Marcia Ponce de León, who is also an anthropologist at the University of Zurich, points out another reason: paleoanthropologists often tacitly assumed that the fossil they had just found was representative for the species, i.e. that it aptly demonstrated the characteristics of the species. Statistically this is not very likely, she says, but nevertheless there were researchers who proposed up to five contemporary species of early «Homo» in Africa, including «Homo habilis», «Homo rudolfensis», «Homo ergaster» and «Homo erectus». Ponce de León sums up the problem as follows: «At present there are as many subdivisions between species as there are researchers examining this problem».
Tracking development of «Homo erectus» over one million years thanks to a change in perspective

Dmanisi now offers the key to the solution. According to Zollikofer, the reason why Skull 5 is so important is that it unites features that have been used previously as an argument for defining different African «species». In other words: «Had the braincase and the face of the Dmanisi sample been found as separate fossils, they very probably would have been attributed to two different species». Ponce de León adds: «It is also decisive that we have five well-preserved individuals in Dmanisi whom we know to have lived in the same place and at the same time». These unique circumstances of the find make it possible to compare variation in Dmanisi with variation in modern human and chimpanzee populations. Zollikofer summarizes the result of the statistical analyses as follows: «Firstly, the Dmanisi individuals all belong to a population of a single early Homo species. Secondly, the five Dmanisi individuals are conspicuously different from each other, but not more different than any five modern human individuals, or five chimpanzee individuals from a given population».

Diversity within a species is thus the rule rather than the exception. The present findings are supported by an additional study recently published in the PNAS journal. In that study, Ponce de León, Zollikofer and further colleagues show that differences in jaw morphology between the Dmanisi individuals are mostly due to differences in dental wear.

This shows the need for a change in perspective: the African fossils from around 1.8 million years ago likely represent representatives from one and the same species, best described as «Homo erectus». This would suggest that «Homo erectus» evolved about 2 million years ago in Africa, and soon expanded through Eurasia – via places such as Dmanisi – as far as China and Java, where it is first documented from about 1.2 million years ago. Comparing diversity patterns in Africa, Eurasia and East Asia provides clues on the population biology of this first global human species.

This makes «Homo erectus» the first «global player» in human evolution. Its redefinition now provides an opportunity to track this fossil human species over a time span of 1 million years.
Literature:

David Lordkipanidze, Marcia S. Ponce de León, Ann Margvelashvili, Yoel Rak, G. Philip Rightmire, Abesalom Vekua, and Christoph P.E. Zollikofer. A complete skull from Dmanisi, Georgia, and the evolutionary biology of early Homo. Science. October 18, 2013. doi: 10.1126/science.1238484

Ann Margvelashvili, Christoph P. E. Zollikofer, David Lordkipanidze, Timo Peltomäki, Marcia S. Ponce de León. Tooth wear and dentoalveolar remodeling are key factors of morphological variation in the Dmanisi mandibles. Proceedings of the National Academy of Sciences of the United States of America (PNAS). September 2, 2013. doi: 10.1073/pnas.1316052110

Research and development collaborative work with huge leverage

The new research findings on Dmanisi are based on collaborative work ongoing for many years between the Anthropological Institute at the University of Zurich and the Georgian National Museum in Tbilisi. The Dmanisi project is financed by SCOPES (Scientific co-operation between Eastern Europe and Switzerland), a research program co-funded by the Swiss National Science Foundation (SNSF) and the Swiss Agency for Development and Co-operation (SDC). This research tool operates with a comparatively modest budget, but has a major and positive impact on the research landscape in the participating countries.

CI SONO MOLTE FOTO INTERESSANTI LE METTI TU?

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Scaring away sharks in AU using recorded sounds of orcas - a theory to be tested but there's concern that it could chase away other animals, upsetting the marine balance.

'Screams' could chase away other marine life
by: Mitchell Nadin
From: The Australian
November 05, 2013 12:00AM

RECORDINGS of killer whale "screams" intended to scare sharks from popular West Australian beaches could end up chasing away other marine life, including dolphins.
http://www.theaustralian.com.au/news/health-science/screams-could-chase-away-other-marine-life/story-e6frg8y6-1226753085502#!

L’astronauta Luca Parmitano è atterrato nella notte dell’11 novembre alle 3:50 a bordo della capsula Soyuz, nelle steppe del Kazakistan.

È giunta al termine la missione da record dell'Agenzia Spaziale Italiana che avuto come protagonista Luca Parmitano, astronauta italiano dell'Agenzia Spaziale Europea e maggiore dell'Aeronautica Militare. Dopo quasi sei mesi sulla Stazione Spaziale Internazionale, oltre 30 esperimenti, due attività extra veicolari e l'attracco di tre navicelle, Luca Parmitano è tornato sulla Terra insieme all'astronauta della NASA Karen Nyberg e al comandante, il cosmonauta Fyodor Yurchikhin.

Sganciandosi dalla Stazione ieri sera, il viaggio di rientro attraverso l'atmosfera è stato brevissimo: l'equipaggio ha ridotto la propria velocità di crociera da 28.800 Km/h in orbita, a zero, nel corso di poco più di tre ore, ed è arrivato a destinazione nelle steppe del Kazakistan.

Secondo un recente studio, 1,1 milioni di persone nella Repubblica Centrafricana rischiano la fame mentre la situazione potrebbe peggiorare a causa dei raccolti ridotti e di una drastica riduzione delle attività economiche a seguito di mesi di violenze nel paese.

Una missione di verifica della sicurezza alimentare d’emergenza, condotta congiuntamente dalle Nazioni Unite, dalle organizzazioni non-governative e dal governo della Repubblica Centrafricana, riporta come 1,1 milioni di persone, circa il 30 per cento della popolazione che vive fuori della capitale Bangui, sia impossibilitato a sfamarsi in maniera regolare o necessiti di assistenza alimentare.

Almeno la metà degli stimati 395.000 sfollati nella Repubblica Centrafricana non ha accesso ad una quantità sufficiente di cibo sano e nutriente, necessario per condurre una vita attiva e in salute.

L’asteroide Vesta non è solo uno dei corpi più antichi del nostro Sistema solare, ma ci sta rivelando che la sua storia evolutiva è molto più complessa di quanto si ritenesse finora. L’ultimo studio sul corpo celeste appena pubblicato sulla rivista Nature,  realizzato grazie ai dati raccolti dallo spettrometro italiano VIR (Visual and InfraRed spectrometer) a bordo della sonda Dawn della NASA  indica infatti che l’olivina, un minerale presente nelle regioni più interne dei pianeti rocciosi come la Terra, risulta quasi del tutto assente nei grandi bacini meridionali di Vesta, che si pensa si siano formati a seguito di impatti con altri corpi celesti e che avrebbero asportato gli strati più esterni della crosta ed esposto il suo mantello. L’olivina è stata invece osservata,  sorprendentemente, in grande abbondanza in una  regione lontana dai bacini sud, nell’emisfero nord.

L’apprezzamento delle opere d’arte figurative aumenta dopo la stimolazione elettrica anodica a bassa intensità della corteccia dorso laterale prefrontale sinistra. Lo rivela uno studio dell’Università di Milano-Bicocca appena pubblicato sulla rivista Social Cognitive and Affective Neuroscience.

Milano, 4 novembre 2013 – Il grado di apprezzamento di un’opera d’arte può aumentare a seguito di una stimolazione elettrica a bassa intensità della corteccia dorso laterale prefrontale sinistra, sede della valutazione estetica. È la conclusione alla quale sono arrivati i ricercatori dell’Università di Milano-Bicocca che hanno pubblicato uno studio sulla rivista Social Cognitive and Affective Neuroscience.

Lo studio (The world can look better: enhancing beauty experience with brain stimulation doi:10.1093/scan/nst165) coordinato da Zaira Cattaneo, ricercatore di Psicobiologia e Psicologia Fisiologica nel dipartimento di Psicologia dell’Università di Milano-Bicocca e presso il Brain Connectivity Center-IRCCS Mondino di Pavia e realizzato con il contributo di Carlotta Lega, dottoranda in Psicologia presso l’ateneo milanese, Albert Flexas, Enric Munar, Camilo J. Cela-Conde dell’Università delle Isole Baleari e Marcos Nadal dell’Università di Vienna, rientra nel campo della neuro estetica, branca delle neuroscienze che si occupa di studiare i correlati neurali alla base dell'apprezzamento estetico.

Si sono conclusi il 22 settembre 2013 gli scavi dell’Istituto Italiano di Paleontologia Umana nel sito pleistocenico di Coste San Giacomo (Anagni) coodiretti da Fabio Parenti e Raffaele Sardella. Nel corso dello scavo, condotto in collaborazione con il  Dipartimento di Scienze della Terra della Sapienza – Università di Roma, sono venuti in luce  numerosissimi fossili di grandi e piccoli mammiferi di circa due milioni di anni fa. Fra essi spiccano per importanza  paleontologica due diverse specie di proboscidati, tre specie di cervi, gazzelle, ippopotami, carnivori come la tigre dai denti a sciabola e iene e, per la prima volta in Europa mediterranea, il lupo etrusco.