244 research outputs found
Analytical solution of a generalized Penna model
In 1995 T.J.Penna introduced a simple model of biological aging. A modified
Penna model has been demonstrated to exhibit behaviour of real-life systems
including catastrophic senescence in salmon and a mortality plateau at advanced
ages. We present a general steady-state, analytic solution to the Penna model,
able to deal with arbitrary birth and survivability functions. This solution is
employed to solve standard variant Penna models studied by simulation.
Different Verhulst factors regulating both the birth rate and external death
rate are considered.Comment: 6 figure
Integrated Health Service Delivery Networks And Tuberculosis Avoidable Hospitalizations: Is There A Relation Between Them In Brazil?
The early identification of the Breathing Symptoms within the scope of Primary Health Care is recommended, and is also one of the strategies of national sanitary authorities for reaching the elimination of tuberculosis. The purpose of this study is to consider which attributes and which territories have shown the most significant progress in Primary Health Care, in terms of coordination of Health Care Networks, and also check if those areas of Primary Health Care that are most critical regarding coordination, there were more or less cases of avoidable hospitalizations for tuberculosis. Methods: This is an ecological study that uses primary and secondary data. For analysis, coropletic maps were developed through the ArcGIS software, version 10.2. There was also the calculation of gross annual and Bayesian rates for hospitalizations for tuberculosis, for each Primary Health Care territory. Results: There were satisfactory results for attributes such as Population (n = 37; 80.4 %), Primary Health Care (n = 43; 93.5 %), Support System (n = 45; 97.8 %); the exceptions were Logistics System (n = 32; 76.0 %) and Governance System, with fewer units in good condition (n = 31; 67.3 %). There is no evidence of any connection between networks' coordination by Primary Health Care and tuberculosis avoidable admissions. Conclusion: The results show that progress has been made regarding the coordination of the Health Care Networks, and a positive trend has been shown, even though the levels are not excellent. It was found no relationship between the critical areas of Primary Health Care and tuberculosis avoidable hospitalizations, possibly because other variables necessary to comprehend the phenomena. © 2016 Popolin et al.16
What is the Nature of EUV Waves? First STEREO 3D Observations and Comparison with Theoretical Models
One of the major discoveries of the Extreme ultraviolet Imaging Telescope
(EIT) on SOHO were intensity enhancements propagating over a large fraction of
the solar surface. The physical origin(s) of the so-called `EIT' waves is still
strongly debated. They are considered to be either wave (primarily fast-mode
MHD waves) or non-wave (pseudo-wave) interpretations. The difficulty in
understanding the nature of EUV waves lies with the limitations of the EIT
observations which have been used almost exclusively for their study. Their
limitations are largely overcome by the SECCHI/EUVI observations on-board the
STEREO mission. The EUVI telescopes provide high cadence, simultaneous
multi-temperature coverage, and two well-separated viewpoints. We present here
the first detailed analysis of an EUV wave observed by the EUVI disk imagers on
December 07, 2007 when the STEREO spacecraft separation was .
Both a small flare and a CME were associated with the wave cadence, and single
temperature and viewpoint coverage. These limitations are largely overcome by
the SECCHI/EUVI observations on-board the STEREO mission. The EUVI telescopes
provide high cadence, simultaneous multi-temperature coverage, and two
well-separated viewpoints. Our findings give significant support for a
fast-mode interpretation of EUV waves and indicate that they are probably
triggered by the rapid expansion of the loops associated with the CME.Comment: Solar Physics, 2009, Special STEREO Issue, in pres
The Fluorescence Detector of the Pierre Auger Observatory
The Pierre Auger Observatory is a hybrid detector for ultra-high energy
cosmic rays. It combines a surface array to measure secondary particles at
ground level together with a fluorescence detector to measure the development
of air showers in the atmosphere above the array. The fluorescence detector
comprises 24 large telescopes specialized for measuring the nitrogen
fluorescence caused by charged particles of cosmic ray air showers. In this
paper we describe the components of the fluorescence detector including its
optical system, the design of the camera, the electronics, and the systems for
relative and absolute calibration. We also discuss the operation and the
monitoring of the detector. Finally, we evaluate the detector performance and
precision of shower reconstructions.Comment: 53 pages. Submitted to Nuclear Instruments and Methods in Physics
Research Section
Update on the correlation of the highest energy cosmic rays with nearby extragalactic matter
Data collected by the Pierre Auger Observatory through 31 August 2007 showed
evidence for anisotropy in the arrival directions of cosmic rays above the
Greisen-Zatsepin-Kuz'min energy threshold, \nobreak{eV}. The
anisotropy was measured by the fraction of arrival directions that are less
than from the position of an active galactic nucleus within 75 Mpc
(using the V\'eron-Cetty and V\'eron catalog). An updated
measurement of this fraction is reported here using the arrival directions of
cosmic rays recorded above the same energy threshold through 31 December 2009.
The number of arrival directions has increased from 27 to 69, allowing a more
precise measurement. The correlating fraction is , compared
with expected for isotropic cosmic rays. This is down from the early
estimate of . The enlarged set of arrival directions is
examined also in relation to other populations of nearby extragalactic objects:
galaxies in the 2 Microns All Sky Survey and active galactic nuclei detected in
hard X-rays by the Swift Burst Alert Telescope. A celestial region around the
position of the radiogalaxy Cen A has the largest excess of arrival directions
relative to isotropic expectations. The 2-point autocorrelation function is
shown for the enlarged set of arrival directions and compared to the isotropic
expectation.Comment: Accepted for publication in Astroparticle Physics on 31 August 201
Evidence for a mixed mass composition at the `ankle' in the cosmic-ray spectrum
We report a first measurement for ultra-high energy cosmic rays of the
correlation between the depth of shower maximum and the signal in the water
Cherenkov stations of air-showers registered simultaneously by the fluorescence
and the surface detectors of the Pierre Auger Observatory. Such a correlation
measurement is a unique feature of a hybrid air-shower observatory with
sensitivity to both the electromagnetic and muonic components. It allows an
accurate determination of the spread of primary masses in the cosmic-ray flux.
Up till now, constraints on the spread of primary masses have been dominated by
systematic uncertainties. The present correlation measurement is not affected
by systematics in the measurement of the depth of shower maximum or the signal
in the water Cherenkov stations. The analysis relies on general characteristics
of air showers and is thus robust also with respect to uncertainties in
hadronic event generators. The observed correlation in the energy range around
the `ankle' at differs significantly from
expectations for pure primary cosmic-ray compositions. A light composition made
up of proton and helium only is equally inconsistent with observations. The
data are explained well by a mixed composition including nuclei with mass . Scenarios such as the proton dip model, with almost pure compositions, are
thus disfavoured as the sole explanation of the ultrahigh-energy cosmic-ray
flux at Earth.Comment: Published version. Added journal reference and DOI. Added Report
Numbe
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