Medical College of Wisconsin New study finds healthy children of Alzheimer patients show early brain changes

Medical College of Wisconsin researchers in Milwaukee have reported that children of Alzheimer's patients who are carriers of a genetic risk factor for Alzheimer's disease have neurological changes that are detectable long before clinical symptoms may appear.

Functional MRI brain imaging revealed that these symptomless carriers of the APOE-4 gene demonstrated significantly reduced functional brain connectivity between the hippocampus and the posterior cingulated cortex, two important brain structures for memory processing. These structures are relevant for information acquisition, filtering and sorting.

The study, conducted at Froedtert Hospital, was led by Shi Jiang Li, Ph.D., professor of biophysics, and was presented at the Alzheimer's Association International Conference on Alzheimer's disease in Chicago, July 29th

"Just as if cancer could be detected when there were only a few cells, decades before it was evident, the advantage of identifying those at great risk for having Alzheimer's would be of tremendous value in development of interventional therapies," says Dr. Li.

The researchers studied 28 neurologically-normal subjects, between ages 45 and 65. Twelve carried the APOE-4 gene and 16 did not. The two groups showed no significant difference in age, educational level, or neuropsychological performances. All subjects received fMRI scans. For each subject, functional connectivity between the two brain structures was measured in a resting state.

Results showed that functional connectivity in the non APOE-4 carriers was approximately 65 percent better than that of the carriers.

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Other members of the research team were Piero Antuono, M.D., professor of neurology, and Zhilin Wu, Ph.D., Chunming Xie, Ph.D., and Jennifer L. Jones, M.S., research associates in the departments of biophysics and neurology.

European Space Agency : COROT finds exoplanet orbiting Sun-like star

Artist's impression of COROT

COROT finds exoplanet orbiting Sun-like star

24 July 2008
A team of European scientists working with COROT have discovered an exoplanet orbiting a star slightly more massive than the Sun. After just 555 days in orbit, the mission has now observed more than

50 000 stars and is adding significantly to our knowledge of the fundamental workings of stars. The latest discovery, COROT-exo-4b is an exoplanet of about the same size as Jupiter. It takes 9.2 days to orbit its star, the longest period for any transiting exoplanet ever found. The team has found that the star, which is slightly larger than our Sun, is rotating at the same pace as the planet's period of revolution. This is quite a surprise for the team, as the planet is thought to be too low in mass and too distant from its star, for the star to have any major influence on its rotation. Light-curve of COROT-exo-4b's parent star Launched in December 2006, COROT is the first space-based mission designed to search for exoplanets. Located outside Earth's atmosphere, the satellite is designed to detect rocky exoplanets almost as small as Earth. The satellite uses transits, the tiny dips in the light output from a star when a planet passes in front of it, to detect and study planets. This is followed up by extensive ground-based observations. Monitoring COROT-exo-4b continuously over several months, the team tracked variations in its brightness between transits. They derived its period of rotation by monitoring dark spots on its surface that rotated in and out of view. It is not known whether COROT-exo-4b and its star have always been rotating in sync since their formation about 1000 million years ago, or if the star’s rotation synchronized later. Studying such systems with COROT will help scientists gain valuable insight into star-planet interactions. This is the first transiting exoplanet found with such a peculiar combination of mass and period of rotation. There is surely something special about how it formed and evolved. Notes for editors: This discovery is being presented today at the Cool Stars 15 meeting at St Andrews University. The ground-based follow-up of the detection of COROT-exo-4b was carried out with the cross-dispersed echelle spectrograph, SOPHIE, on the 1.8-m telescope at the Observatoire de Haute Provence (France), the High Accuracy Radial velocity Planet Searcher, HARPS on the 3.6-m telescope at La Silla observatory (Chile) and the cross-dispersed echelle spectrograph, UVES on the 8.2-m Very Large Telescope at Paranal (Chile), the 1-m telescope at the Wise Observatory in Israel, the 1-m Euler telescope at La Silla, and the 3.6-m Canada-France-Hawaii telescope. COROT is a CNES project with ESA participation. The other major partners in this mission are Austria, Belgium, Brazil, Germany and Spain. For more information: Malcolm Fridlund, ESA COROT Project Scientist Email: Malcolm.Fridlund @ esa.int

ESO : Watching a 'New Star' Make the Universe Dusty

VLTI observes for the first time how dust forms around an erupting star

Using ESO's Very Large Telescope Interferometer, and its remarkable acuity, astronomers were able for the first time to witness the appearance of a shell of dusty gas around a star that had just erupted, and follow its evolution for more than 100 days. This provides the astronomers with a new way to estimate the distance of this object and obtain invaluable information on the operating mode of stellar vampires, dense stars that suck material from a companion.

ESO PR Photo 22/08
Dust shells around a nova

Although novae were first thought to be new stars appearing in the sky, hence their Latin name, they are now understood as signaling the brightening of a small, dense star. Novae occur in double star systems comprising a white dwarf - the end product of a solar-like star - and, generally, a low-mass normal star - a red dwarf. The two stars are so close together that the red dwarf cannot hold itself together and loses mass to its companion. Occasionally, the shell of matter that has fallen onto the ingesting star becomes unstable, leading to a thermonuclear explosion which makes the system brighter.

Nova Scorpii 2007a (or V1280 Scorpii), was discovered by Japanese amateur astronomers on 4 February 2007 towards the constellation Scorpius ("the Scorpion"). For a few days, it became brighter and brighter, reaching its maximum on 17 February, to become one of the brightest novae of the last 35 years. At that time, it was easily visible with the unaided eye.

Eleven days after reaching its maximum, astronomers witnessed the formation of dust around the object. Dust was present for more than 200 days, as the nova only slowly emerged from the smoke between October and November 2007. During these 200 days, the erupting source was screened out efficiently, becoming more than 10,000 times dimmer in the visual.

An unprecedented high spatial resolution monitoring of the dust formation event was carried out with the Very Large Telescope Interferometer (VLTI), extending over more than 5 months following the discovery. The astronomers first used the AMBER near-infrared instrument, then, as the nova continued to produce dust at a high rate, they moved to using the MIDI mid-infrared instrument, that is more sensitive to the radiation of the hot dust. Similarly, as the nova became fainter, the astronomers switched from the 1.8-m Auxiliary Telescopes to their larger brethren, the 8.2-m Unit Telescopes. With the interferometry mode, the resolution obtained is equivalent to using a telescope with a size between 35 and 71 metres (the distance between the 2 telescopes used).

The first observations, secured 23 days after the discovery, showed that the source was very compact, less than 1 thousandth of an arcsecond (1 milli-arcsecond or mas), which is a size comparable to viewing one grain of sand from about 100 kilometres away. A few days later, after the detection of the major dust formation event, the source measured 13 mas.

"It is most likely that the latter size corresponds to the diameter of the dust shell in expansion, while the size previously measured was an upper limit of the erupting source," explains lead author Olivier Chesneau. Over the following months the dusty shell expanded regularly, at a rate close to 2 million km/h.

"This is the first time that the dust shell of a nova is spatially resolved and its evolution traced starting from the onset of its formation up to the point that it becomes too diluted to be seen", says co-author Dipankar Banerjee, from India.

The measurement of the angular expansion rate, together with the knowledge of the expansion velocity, enables the astronomer to derive the distance of the object, in this case about 5500 light-years.

"This is a new and promising technique for providing distances of close novae. This was made possible because the state of the art facility of the VLTI, both in terms of infrastructure and management of the observations, allows one to schedule such observations," says co-author Markus Wittkowski from ESO.

Moreover, the quality of the data provided by the VLTI was such that it was possible to estimate the daily production of dust and infer the total mass ejected. "Overall, V1280 Sco probably ejected more than the equivalent of 33 times the mass of the Earth, a rather impressive feat if one considers that this mass was ejected from a star not larger in radius than the Earth," concludes Chesneau. Of this material, about a percent or less was in the form of dust.

More information

"VLTI monitoring of the dust formation event of the Nova V1280 Sco", by O. Chesneau et al. appears today in the research journal Astronomy and Astrophysics.

The team is composed of O. Chesneau, S. Sacuto, and A. Spang (CNRS/OCA, Grasse, France), D. P. K. Banerjee, N. M. Ashok and R. K. Das, (Physical Research Laboratory, Gujarat, India), F. Millour, N. Nardetto and S. Kraus (Max-Planck-Institut für Radioastronomie, Bonn, Germany), E. Lagadec (Department of Physics and Astronomy University of Manchester, UK), and M. Wittkowski, C. Hummel, M. Petr-Gotzens, S. Morel, F. Rantakyro, and M. Schöller (ESO).
A French press release is available at http://fizeau.unice.fr/article.php3?id_article=189

Contacts

Olivier Chesneau
Observatoire de la Côte d'Azur, Dpt. Fizeau
Grasse, France
Phone: +33 4 93 40 53 40
E-mail: Olivier.Chesneau (at) obs-azur.fr

ESA/Hubble Information Centre : Lenses galore - Hubble finds large sample of very distant galaxies

24-Jul-2008: New Hubble Space Telescope observations of six spectacular galaxy clusters acting as gravitational lenses have given significant insights into the early stages of the Universe. Scientists have found the largest sample of very distant galaxies seen to date: ten promising candidates thought to lie at a distance of 13 billion light-years (~redshift 7.5). By using the gravitational magnification from six massive lensing galaxy clusters, the NASA/ESA Hubble Space Telescope has provided scientists with the largest sample of very distant galaxies seen to date. Some of the newly found magnified objects are dimmer than the faintest ones seen in the legendary Hubble Ultra Deep Field, which is usually considered the deepest image of the Universe. By combining both visible and near-infrared observations from Hubble’s Advanced Camera for Surveys (ACS) and Near Infrared Camera and Multi-Object Spectrometer (NICMOS), scientists searched for galaxies that are only visible in near-infrared light. They uncovered 10 candidates believed to lie about 13 billion light-years away (a redshift of approximately 7.5), which means that the light gathered was emitted by the stars when the Universe was still very young — a mere 700 million years old. “These candidates could well explain one of the big puzzles plaguing astronomy today. We know that the Universe was reionised within the first 5-600 million years after the Big Bang, but we don’t know if the ionising energy came from a smaller number of big galaxies or a more plentiful population of tiny ones”, said Johan Richard, from the California Institute of Technology. The relatively high number of redshift 7.5 galaxies claimed in this survey suggests that most of the ionising energy was produced by dim and abundant galaxies rather than large, scarce ones. “The challenge for astronomers is that galaxies beyond a distance of 13 billion light-years (past a redshift of 7) are exceedingly faint and are only visible in the near-infrared — just at the limit of what Hubble can observe” explained Jean-Paul Kneib from the Laboratoire d’Astrophysique de Marseille. This new result was only made possible with some cosmic assistance in the form of gravitational lensing that magnified the light from the distant galaxies enough for Hubble to detect them. A firm confirmation of their distance was beyond even the capabilities of the 10-meter Keck telescope and must await powerful future ground-based telescopes. First observationally confirmed in 1979, gravitational lenses were predicted by Albert Einstein’s theory of General Relativity, a theory that allows astronomers to calculate the path of starlight as it moves through curved space-time. According to the theory, the bending of light is brought about by the presence of matter in the Universe, which causes the fabric of space-time to warp and curve. Gravitational lensing is the result of this warping of spacetime and is mainly detected around very massive galaxy clusters. Due to the gravitational effect of both the cluster’s observable matter and hidden dark matter, the light is bent around the cluster. This bending of light allows the clusters in certain places to act as natural gravitational telescopes that give the light of faint and faraway objects a boost. Where Earth-bound telescopes fail to detect such faint and distant objects due to the blurring introduced by the Earth’s atmosphere, a combination of Hubble’s location in space and the magnification of the gravitation lenses provides astronomers with a birds-eye view of these elusive objects. This technique has already been used numerous times by Hubble and has helped astronomers to find and study many of the most distant known galaxies. Notes for editors: The Hubble Space Telescope is a project of international cooperation between ESA and NASA. Image credit: NASA, ESA and Johan Richard (Caltech, USA) Acknowledgement: Davide de Martin & James Long (ESA/Hubble) Links: Science paper Wikipedia site explaining Gravitational Lensing More Hubble discoveries relating to gravitational lenses Contacts: Johan Richard Department of Astrophysics, California Institute of Technology Tel: +1-626-395-3293 E-mail: johan@astro.caltech.edu Jean-Paul Kneib Department of Astrophysics, California Institute of Technology Laboratoire d'Astrophysique de Marseille Cell: +33-685-988-265 E-mail: jean-paul.kneib@oamp.fr Richard Ellis Department of Astrophysics, Oxford California Institute of Technology Tel: +44-1865-283124 Cellular: +44-7885-403334 E-mail: rse@astro.caltech.edu Lars Lindberg Christensen Hubble/ESA, Garching, Germany Tel: +49-89-3200-6306 Cellular: +49-173-3872-621 E-mail: lars@eso.org

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Science and Technology Facilities Council : Polarised sunglasses see black hole disks

For the first time astronomers have found a way to get a clean view of the elusive disks of matter surrounding supermassive black holes. By using a polarising filter on the Science and Technology Facility Council’s UK Infrared Telescope (UKIRT) in Hawaii, they have been able to see through the clouds of dust which surround these black holes. This work is published on 24th July 2008 in Nature.

This figure schematically shows how the team's polarization observation works.

In a similar way that a fisherman would wear polarised sunglasses to help get rid of the glare from the water surface and allow him to see more clearly under the water, the filter on the telescope allowed the astronomers to see beyond surrounding clouds of dust and gas to the blue colour of the disk in infrared light.

It is believed that most, if not all, galaxies have a supermassive black hole in their centre, and this is an area of intense research within astronomy. Studying these black holes and discovering more about their structure can be difficult as they are so far away from us.

Also, the clouds of gas and dust which surround the black holes make it difficult to achieve a clean, uncontaminated spectrum of the black hole vicinity.

Andy Lawrence, of the University of Edinburgh's Institute for Astronomy, and co-investigator on the project, says “For decades there has been a theory that supermassive black holes should be accumulating materials in the form of a disk …but until now this has been impossible to test due to the contamination by the dust clouds.”

The team, led by Makoto Kishimoto of the Max Planck Institut fuer Radioastronomie, have found a way around this problem.

Looking at UKIRT on Mauna Kea through IRPOL

Some of the black holes have a very small amount of scattered light coming from the vicinity of the black hole itself, rather than the clouds of gas and dust around it. This light has become polarised after hitting matter within the disk. By using a filter that only allows this polarised light to come through and blocks out the unpolarised light from the gas clouds, they were able to visually eliminate them and reveal the disk.

This new method could help astronomers in their understanding of the outermost region of the disks where important questions are still to be answered: how and where the disk ends, and how material is being supplied to the disk.

Dr. Chris Davis of the Joint Astronomy Centre, the facility operating UKIRT, says: "UKIRT has long been at the forefront of infrared astronomy, and has been a leader in the niche area of infrared polarimetry for almost two decades. Without facilities like the infrared polarimeter (IRPOL), even with the very largest telescopes in the world, exciting discoveries like those of Kishimoto and his colleagues could not be made."

ESO : Accretion Discs Show Their True Colours

VLT observations of quasars reconcile observations with models

Quasars are the brilliant cores of remote galaxies, at the hearts of which lie supermassive black holes that can generate enough power to outshine the Sun a trillion times. These mighty power sources are fuelled by interstellar gas, thought to be sucked into the hole from a surrounding 'accretion disc'. A paper in this week's issue of the journal Nature, partly based on observations collected with ESO's Very Large Telescope, verifies a long-standing prediction about the intensely luminous radiation emitted by these accretion discs.

ESO PR Photo 21/08
Uncovering the inner disc

"Astronomers were puzzled by the fact that the best models of these discs couldn't quite be reconciled with some of the observations, in particular, with the fact that these discs did not appear as blue as they should be," explains lead-author Makoto Kishimoto.

Such a discrepancy could be the signal that there was something very wrong with the models. With his colleagues, he investigated this discrepancy by studying the polarised light from six quasars. This enabled them to demonstrate that the disc spectrum is as blue as predicted.

"The crucial observational difficulty here has been that the disc is surrounded by a much larger torus containing hot dust, whose light partly outshines that of the disc," says Kishimoto. "Because the light coming from the disc is scattered in the disc vicinity and thus polarised, by observing only polarised light from the quasars, one can uncover the buried light from the disc."

In a similar way that a fisherman would wear polarised sunglasses to help get rid of the glare from the water surface and allow him to see more clearly under the water, the filter on the telescope allowed the astronomers to see beyond surrounding clouds of dust and gas to the blue colour of the disc in infrared light.

The observations were done with the FORS and ISAAC instruments on one of the 8.2-m Unit Telescopes of ESO's Very Large Telescope, located in the Atacama Desert, in Chile, as well as several other telescopes, including STFC's UKIRT.

The standard picture of the accretion disc is therefore vindicated. The authors believe that further measurements could eventually provide valuable insight into how and where the disc ends, and how material is being supplied to the disc.

More information

"The characteristic blue spectra of accretion disks in quasars as uncovered in the infrared," by Makoto Kishimoto et al., appears in the 24 July 2008 issue of the journal Nature. The team is composed of Makoto Kishimoto (Max-Planck-Institut für Radioastronomie, Bonn, Germany), Robert Antonucci, Omer Blaes, and Christian Leipski (University of California, Santa Barbara, USA), Andy Lawrence (SUPA, University of Edinburgh, UK), Catherine Boisson (LUTH, Observatoire de Paris, France), and Marcus Albrecht (Universidad Catolica del Norte, Chile).

Contacts

Makoto Kishimoto
Max-Planck-Institut für Radioastronomie
Bonn, Germany
Phone: +49 228 525 186
E-mail: mk (at) mpifr-bonn.mpg.de

ESO Press Officer: Dr. Henri Boffin - +49 89 3200 6222 - hboffin@eso.org
ESO Press Officer in Chile: Valentina Rodriguez - +56 2 463 3123 - vrodrigu@eso.org

Physikalisch-Technische Bundesanstalt (PTB) : Shielding for ambitious neutron experiment

PTB expertise supports research for better understanding of antimaterial

In science fiction stories it is either the inexhaustible energy source of the future or a superweapon of galactic magnitude: antimaterial. In fact, antimaterial can neither be found on Earth nor in space, is extremely complex to produce and thus difficult to study. In order to nevertheless track down the origin of material and antimaterial in the universe, a European research group is measuring the power of the electrical dipole moment of neutrons, which represents a measure for the different physical properties of material and antimaterial. The prerequisite for further, still more accurate measurements is a perfect insulation against electrical and magnetic radiation from the environment. Magnetically soft mumetal serves as a material of the new shielding - the design, testing and set-up of which the Physikalisch-Technische Bundesanstalt is responsible.

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PTB-Contact:
Dr. Allard Schnabel, Fachbereich 8.2 Biosignale, Tel. (030) 3481-7423, E-Mail: Allard.Schnabel@ptb.de
Dr. Martin Burghoff, Fachbereich 8.2 Biosignale, Tel. (030) 3481-7238, E-Mail: Martin.Burghoff@ptb.de

Information on mu-metal cabin at PTB
http://www.ptb.de/en/publikationen/blickpunkt/_biomagnetismus.html

List of involved research institutions
http://nedm.web.psi.ch

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