2,378 research outputs found
Effects of the galactic magnetic field upon large scale anisotropies of extragalactic Cosmic Rays
The large scale pattern in the arrival directions of extragalactic cosmic
rays that reach the Earth is different from that of the flux arriving to the
halo of the Galaxy as a result of the propagation through the galactic magnetic
field. Two different effects are relevant in this process: deflections of
trajectories and (de)acceleration by the electric field component due to the
galactic rotation. The deflection of the cosmic ray trajectories makes the flux
intensity arriving to the halo from some direction to appear reaching the Earth
from another direction. This applies to any intrinsic anisotropy in the
extragalactic distribution or, even in the absence of intrinsic anisotropies,
to the dipolar Compton-Getting anisotropy induced when the observer is moving
with respect to the cosmic rays rest frame. For an observer moving with the
solar system, cosmic rays traveling through far away regions of the Galaxy also
experience an electric force coming from the relative motion (due to the
rotation of the Galaxy) of the local system in which the field can be
considered as being purely magnetic. This produces small changes in the
particles momentum that can originate large scale anisotropies even for an
isotropic extragalactic flux.Comment: 11 pages, 4 figure
Recent results from the Pierre Auger Observatory
The main results from the Auger Observatory are described. A steepening of
the spectrum is observed at the highest energies, supporting the expectation
that above eV the cosmic ray energies are significantly
degraded by interactions with the CMB photons (the GZK effect). This is further
supported by the correlations observed above eV with the
distribution of nearby active galaxies, which also show the potential of Auger
to start the era of charged particle astronomy. The lack of observation of
photons or neutrinos strongly disfavors top-down models, and these searches may
approach in the long term the sensitivity required to test the fluxes expected
from the secondaries of the very same GZK process. Bounds on the anisotropies
at EeV energies contradict hints from previous experiments that suggested a
large excess from regions near the Galactic centre or the presence of a dipolar
type modulation of the cosmic ray flux.Comment: 6 p., 8 figs., proceedings of the XXIII International Conference on
Neutrino Physics and Astrophysics (Neutrino 08
Search for single sources of ultra high energy cosmic rays on the sky
In this paper, we suggest a new way to identify single bright sources of
Ultra High Energy Cosmic Rays (UHECR) on the sky, on top of background. We look
for doublets of events at the highest energies, E > 6 x 10^19 eV, and identify
low energy tails, which are deflected by the Galactic Magnetic Field (GMF). For
the sources which are detected, we can recover their angular positions on the
sky within one degree from the real ones in 68% of cases. The reconstruction of
the deflection power of the regular GMF is strongly affected by the value of
the turbulent GMF. For typical values of 4 microG near the Earth, one can
reconstruct the deflection power with 25% precision in 68% of cases.Comment: 20 pages, 10 figures. Corresponds to the version published in JCA
International Research Collaboration in Small and Big Science: Comparing Global Research Output Between Biofuels and Neutron Scattering
Atlanta Conference on Science and Innovation Policy 2009This presentation was part of the session : Globalization of Science and InnovationThis material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder. ©2009 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.We investigate patterns of international research collaboration in two different fields: biofuels, and neutron scattering. We use bibliometric analysis with data retrieved from the Science Citation Index, through Web of Science from 2003 through 2008. We find that international collaboration in relation to the number of publications in the field is more intense in neutron scattering than in biofuels. Moreover, international teams in neutron scattering include more countries than is the case in biofuels. We also find that publications in biofuels have increased faster among some of the BRIC (Brazil, India, China) countries than among the U.S. and European countries. In neutron scattering publications remain concentrated in more developed countries. The U.S. remains the leader in scientific production in both fields. The emergence of developing countries as producers of science in biofuels suggests opportunities for North-South collaboration in research.U.S. National Science Foundatio
Ultrahigh Energy Nuclei in the Galactic Magnetic Field
Observations are consistent with a significant fraction of heavy nuclei in
the cosmic ray flux above a few times 10^19 eV. Such nuclei can be deflected
considerably in the Galactic magnetic field, with important implications for
the search of their sources. We perform detailed simulations of heavy nuclei
propagation within recent Galactic magnetic field models. While such models are
not yet sufficiently constrained to predict deflection maps in detail, we find
general features of the distribution of (de-) magnified flux from sources.
Since in most theoretical models sources of heavy nuclei are located in the
local large scale structure of galaxies, we show examples of images of several
nearby galaxy clusters and of the supergalactic plane. Such general features
may be useful to develop efficient methods for source reconstruction from
observed ultrahigh energy cosmic ray arrival directions.Comment: 17 pages, 11 figures. Published in JCA
Clinical Medicine and Clinical Trials
The author discusses the role of clinical trials in clinical medicine
Gravity of Monopole and String and Gravitational Constant in 3He-A
We discuss the effective metric produced in superfluid 3He-A by such
topological objects as radial disgyration and monopole. In relativistic
theories these metrics are similar to that of the local string and global
monopole correspondingly. But in 3He-A they have the negative angle deficit,
which corresponds to the negative mass of the topological objects. The
effective gravitational constant G in superfluid 3He-A, derived from the
comparison with relativistic theories, is inversely proportional to the square
of the gap amplitude Delta, which plays the part of the Planck energy cut-off.
G depends on temperature and increases with T, which corresponds to the vacuum
screening of the Newton's constant.Comment: Latex file, 10 pages, no figure
Sirolimus Therapy for Patients With Lymphangioleiomyomatosis Leads to Loss of Chylous Ascites and Circulating LAM Cells
A young woman received a diagnosis of abdominal, sporadic lymphangioleiomyomatosis (LAM) and multiple abdominal lymphangioleiomyomas and was referred for recurrent chylous ascites responding only to a fat-free diet. On admission, pulmonary function test (PFT) results showed a moderate reduction in the transfer factor for carbon monoxide with normal exercise performance. The serum vascular endothelial growth factor D (VEGF-D) level was 2,209 pg/mL. DNA sequences, amplified at loci kg8, D16S3395, D16S3024, D16S521, and D16S291 on chromosome 16p13.3, showed a loss of heterozygosity (LOH) only for kg8. Fat-free total parenteral nutrition in association with sirolimus (2 mg po daily) was initiated. Serum sirolimus levels were maintained at concentrations between 5 and 15 ng/mL. After 1 month, reintroduction of a low-fat oral feeding was achieved without recurrence of ascites. PFT results were stable. Interestingly, clinical improvement was associated with a reduction in the VEGF-D serum level (1,558 pg/mL). LOH at the kg8 biomarker in blood LAM cells was no longer detected
The origins of quark-hadron duality: How does the square of the sum become the sum of the squares?
Bloom-Gilman duality demonstrates empirically that the electroproduction of
's at low momentum transfers averages smoothly around the scaling curve
measured at large momentum transfers. The latter is proportional to the sum of
the squares of the constituent charges whereas the former involves the coherent
excitation of resonances and is driven by the square of summed constituent
charges. We determine the minimal necessary conditions for this equality to be
realised so that duality can occur and consider the implications for a range of
processes that may be studied soon at CEBAF.Comment: 9 page
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