545 research outputs found
Multivariate statistic analysis of the world population ageing
© 2014, Mediterranean Center of Social and Educational Research. All right reserved. The research is devoted to the issue of the ageing of population, which is one of the global problems of the modern world. World countries have been grouped according to the amount of people over 65 years old. The conclusions about spatial differentiation of the ageing population have been drawn. The groups of states with a different level of population ageing were singled out. The amount of ageing population have been forecasted
Feasibility of a Small, Rapid Optical-to-IR Response, Next Generation Gamma Ray Burst Mission
We present motivations for and study feasibility of a small, rapid optical to
IR response gamma ray burst (GRB) space observatory. By analyzing existing GRB
data, we give realistic detection rates for X-ray and optical/IR instruments of
modest size under actual flight conditions. Given new capabilities of fast
optical/IR response (about 1 s to target) and simultaneous multi-band imaging,
such an observatory can have a reasonable event rate, likely leading to new
science. Requiring a Swift-like orbit, duty cycle, and observing constraints, a
Swift-BAT scaled down to 190 square cm of detector area would still detect and
locate about 27 GRB per yr. for a trigger threshold of 6.5 sigma. About 23
percent of X-ray located GRB would be detected optically for a 10 cm diameter
instrument (about 6 per yr. for the 6.5 sigma X-ray trigger).Comment: Elaborated text version of a poster presented at 2012 Malaga/Marbella
symposiu
Possible structure in the cosmic ray electron spectrum measured by the ATIC-2 and ATIC-4 experiments
A strong excess in a form of a wide peak in the energy range of 300-800 GeV
was discovered in the first measurements of the electron spectrum in the energy
range from 20 GeV to 3 TeV by the balloon-borne experiment ATIC (J. Chang et
al. Nature, 2008). The experimental data processing and analysis of the
electron spectrum with different criteria for selection of electrons,
completely independent of the results reported in (J. Chang et al. Nature,
2008) is employed in the present paper. The new independent analysis generally
confirms the results of (J. Chang et al. Nature, 2008), but shows that the
spectrum in the region of the excess is represented by a number of narrow
peaks. The measured spectrum is compared to the spectrum of (J. Chang et al.
Nature, 2008) and to the spectrum of the Fermi/LAT experiment.Comment: LaTeX2e, 10 pages, 4 figures, a paper for ECRS 2010 (Turku, Finland);
http://www.astrophys-space-sci-trans.net/7/119/2011
Upturn observed in heavy nuclei to iron ratios by the ATIC-2 experiment
The ratios of fluxes of heavy nuclei from sulfur (Z=16) to chromium (Z=24) to
the flux of iron were measured by the ATIC-2 experiment. The ratios are
decreasing functions of energy from 5 GeV/n to approximately 80 GeV/n, as
expected. However, an unexpected sharp upturn in the ratios are observed for
energies above 100 GeV/n for all elements from Z=16 to Z=24. Similar upturn but
with lower amplitude was also discovered in the ATIC-2 data for the ratio of
fluxes of abundant even nuclei (C, O, Ne, Mg, Si) to the flux of iron.
Therefore the spectrum of iron is significantly different from the spectra of
other abundant even nuclei.Comment: 4 pages, LaTeX2e, a paper for 23rd European Cosmic Ray Symposium
(2012
Improved Constraints on the Preferential Heating and Acceleration of Oxygen Ions in the Extended Solar Corona
We present a detailed analysis of oxygen ion velocity distributions in the
extended solar corona, based on observations made with the Ultraviolet
Coronagraph Spectrometer (UVCS) on the SOHO spacecraft. Polar coronal holes at
solar minimum are known to exhibit broad line widths and unusual intensity
ratios of the O VI 1032, 1037 emission line doublet. The traditional
interpretation of these features has been that oxygen ions have a strong
temperature anisotropy, with the temperature perpendicular to the magnetic
field being much larger than the temperature parallel to the field. However,
recent work by Raouafi and Solanki suggested that it may be possible to model
the observations using an isotropic velocity distribution. In this paper we
analyze an expanded data set to show that the original interpretation of an
anisotropic distribution is the only one that is fully consistent with the
observations. It is necessary to search the full range of ion plasma parameters
to determine the values with the highest probability of agreement with the UVCS
data. The derived ion outflow speeds and perpendicular kinetic temperatures are
consistent with earlier results, and there continues to be strong evidence for
preferential ion heating and acceleration with respect to hydrogen. At
heliocentric heights above 2.1 solar radii, every UVCS data point is more
consistent with an anisotropic distribution than with an isotropic
distribution. At heights above 3 solar radii, the exact probability of isotropy
depends on the electron density chosen to simulate the line-of-sight
distribution of O VI emissivity. (abridged abstract)Comment: 19 pages (emulateapj style), 13 figures, ApJ, in press (v. 679; May
20, 2008
Relative abundances of cosmic ray nuclei B-C-N-O in the energy region from 10 GeV/n to 300 GeV/n. Results from ATIC-2 (the science flight of ATIC)
The ATIC balloon-borne experiment measures the energy spectra of elements
from H to Fe in primary cosmic rays from about 100 GeV to 100 TeV. ATIC is
comprised of a fully active bismuth germanate calorimeter, a carbon target with
embedded scintillator hodoscopes, and a silicon matrix that is used as the main
charge detector. The silicon matrix produces good charge resolution for protons
and helium but only partial resolution for heavier nuclei. In the present
paper, the charge resolution of ATIC was improved and backgrounds were reduced
in the region from Be to Si by using the upper layer of the scintillator
hodoscope as an additional charge detector. The flux ratios of nuclei B/C, C/O,
N/O in the energy region from about 10 GeV/nucleon to 300 GeV/nucleon obtained
from this high-resolution, high-quality charge spectra are presented, and
compared with existing theoretical predictions.Comment: 4 pages,2 figures, a paper for 30-th International Cosmic Rays
Conferenc
The Tunka Experiment: Towards a 1-km^2 Cherenkov EAS Array in the Tunka Valley
The project of an EAS Cherenkov array in the Tunka valley/Siberia with an
area of about 1 km^2 is presented. The new array will have a ten times bigger
area than the existing Tunka-25 array and will permit a detailed study of the
cosmic ray energy spectrum and the mass composition in the energy range from
10^15 to 10^18 eV.Comment: 3 pages, 2 figures, to be published in IJMP
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