1,049 research outputs found
A new parametric equation of state and quark stars
It is still a matter of debate to understand the equation of state of cold
supra-nuclear matter in compact stars because of unknown on-perturbative strong
interaction between quarks. Nevertheless, it is speculated from an
astrophysical view point that quark clusters could form in cold quark matter
due to strong coupling at realistic baryon densities. Although it is hard to
calculate this conjectured matter from first principles, one can expect the
inter-cluster interaction to share some general features to nucleon-nucleon
interaction. We adopt a two-Gaussian component soft-core potential with these
general features and show that quark clusters can form stable simple cubic
crystal structure if we assume Gaussian form wave function. With this
parameterizing, Tolman-Oppenheimer-Volkoff equation is solved with reasonable
constrained parameter space to give mass-radius relation of crystalline solid
quark star. With baryon densities truncated at 2 times nuclear density at
surface and range of interaction fixed at 2fm we can reproduce similar
mass-radius relation to that obtained with bag model equations of state. The
maximum mass ranges from about 0.5 to 3 solar mass. Observed maximum pulsar
mass (about 2 solar mass) is then used to constrain parameters of this simple
interaction potential.Comment: 5 pages, 2 figure
Laboratory spectral calibration of the TanSat atmospheric carbon dioxide grating spectrometer
TanSat is a key satellite mission in the Chinese Earth Observation program
and is designed to measure the global atmospheric column-averaged dry-air
CO2 mole fraction by measuring the visible and near-infrared
solar-reflected spectra. The first Chinese super-high-resolution grating
spectrometer for measuring atmospheric CO2 is aboard TanSat. This
spectrometer is a suite incorporating three grating spectrometers that make
coincident measurements of reflected sunlight in the near-infrared
CO2 band near 1.61 and 2.06 µm and in the molecular oxygen
(O2) A-band at 0.76 µm. The spectral resolving power
(λ∕Δλ) values are ∼ 19 000, ∼ 12 800, and
∼ 12 250 in the O2 A-band, and the weak and strong absorption bands of
CO2, respectively. This paper describes the prelaunch spectral
calibration of the atmospheric carbon dioxide grating spectrometer aboard
TanSat. Several critical aspects of the spectrometer, including the spectral
resolution, spectral dispersion, and the instrument line shape function of
each channel, which are directly related to producing the Level 1 products
are evaluated in this paper. The instrument line shape function of the
spectrometer is notably symmetrical and perfectly consistent across all
channels in the three bands. The symmetry is better then 99.99 %, and the
consistency in the worst case is better then 99.97 %, 99.98 %, and 99.98 %
in the O2 A, WCO2, and SCO2 bands, respectively. The
resulting variations in the spectral calibrations and the radiometric response
errors are negligible. The spectral resolution characterizations meet the
mission requirements. The spectral dispersions have excellent consistency in
the spatial dimension of each band, and there is good linearity in the
spectral dimension of each band. The RMS errors of the fitting residuals are
0.9, 1, and 0.7 pm in the O2 A-band, the WCO2 band, and the
SCO2 band, respectively. Taken together, these results suggest that
the spectral characterizations of the spectrometer aboard TanSat meet the
mission requirements.</p
An Updated Search of Steady TeV Ray Point Sources in Northern Hemisphere Using the Tibet Air Shower Array
Using the data taken from Tibet II High Density (HD) Array (1997
February-1999 September) and Tibet-III array (1999 November-2005 November), our
previous northern sky survey for TeV ray point sources has now been
updated by a factor of 2.8 improved statistics. From to
in declination (Dec) range, no new TeV ray point
sources with sufficiently high significance were identified while the
well-known Crab Nebula and Mrk421 remain to be the brightest TeV ray
sources within the field of view of the Tibet air shower array. Based on the
currently available data and at the 90% confidence level (C.L.), the flux upper
limits for different power law index assumption are re-derived, which are
approximately improved by 1.7 times as compared with our previous reported
limits.Comment: This paper has been accepted by hepn
Nitrated α-Synuclein Induces the Loss of Dopaminergic Neurons in the Substantia Nigra of Rats
BACKGROUND: The pathology of Parkinson's disease (PD) is characterized by the degeneration of the nigrostriatal dopaminergic pathway, as well as the formation of intraneuronal inclusions known as Lewy bodies and Lewy neurites in the substantia nigra. Accumulations of nitrated alpha-synuclein are demonstrated in the signature inclusions of Parkinson's disease. However, whether the nitration of alpha-synuclein is relevant to the pathogenesis of PD is unknown. METHODOLOGY/PRINCIPAL FINDINGS: In this study, effect of nitrated alpha-synuclein to dopaminergic (DA) neurons was determined by delivering nitrated recombinant TAT-alpha-synuclein intracellular. We provide evidence to show that the nitrated alpha-synuclein was toxic to cultured dopaminergic SHSY-5Y neurons and primary mesencephalic DA neurons to a much greater degree than unnitrated alpha-synuclein. Moreover, we show that administration of nitrated alpha-synuclein to the substantia nigra pars compacta of rats caused severe reductions in the number of DA neurons therein, and led to the down-regulation of D(2)R in the striatum in vivo. Furthermore, when administered to the substantia nigra of rats, nitrated alpha-synuclein caused PD-like motor dysfunctions, such as reduced locomotion and motor asymmetry, however unmodified alpha-synuclein had significantly less severe behavioral effects. CONCLUSIONS/SIGNIFICANCE: Our results provide evidence that alpha-synuclein, principally in its nitrated form, induce DA neuron death and may be a major factor in the etiology of PD
Outlook for inverse design in nanophotonics
Recent advancements in computational inverse design have begun to reshape the
landscape of structures and techniques available to nanophotonics. Here, we
outline a cross section of key developments at the intersection of these two
fields: moving from a recap of foundational results to motivation of emerging
applications in nonlinear, topological, near-field and on-chip optics.Comment: 13 pages, 6 figure
Does or did the supernova remnant Cassiopeia A operate as a PeVatron?
For decades, supernova remnants (SNRs) have been considered the prime sources
of Galactic Cosmic rays (CRs). But whether SNRs can accelerate CR protons to
PeV energies and thus dominate CR flux up to the knee is currently under
intensive theoretical and phenomenological debate. The direct test of the
ability of SNRs to operate as CR PeVatrons can be provided by ultrahigh-energy
(UHE; ~TeV) -rays. In this context, the historical
SNR Cassiopeia A (Cas A) is considered one of the most promising target for UHE
observations. This paper presents the observation of Cas A and its vicinity by
the LHAASO KM2A detector. The exceptional sensitivity of LHAASO KM2A in the UHE
band, combined with the young age of Cas A, enabled us to derive stringent
model-independent limits on the energy budget of UHE protons and nuclei
accelerated by Cas A at any epoch after the explosion. The results challenge
the prevailing paradigm that Cas A-type SNRs are major suppliers of PeV CRs in
the Milky Way.Comment: 11 pages, 3 figures, Accepted by the APJ
Measurement of ultra-high-energy diffuse gamma-ray emission of the Galactic plane from 10 TeV to 1 PeV with LHAASO-KM2A
The diffuse Galactic -ray emission, mainly produced via interactions
between cosmic rays and the interstellar medium and/or radiation field, is a
very important probe of the distribution, propagation, and interaction of
cosmic rays in the Milky Way. In this work we report the measurements of
diffuse -rays from the Galactic plane between 10 TeV and 1 PeV
energies, with the square kilometer array of the Large High Altitude Air Shower
Observatory (LHAASO). Diffuse emissions from the inner
(, ) and outer
(, ) Galactic plane are detected with
and significance, respectively. The outer Galactic
plane diffuse emission is detected for the first time in the very- to
ultra-high-energy domain (~TeV). The energy spectrum in the inner Galaxy
regions can be described by a power-law function with an index of
, which is different from the curved spectrum as expected from
hadronic interactions between locally measured cosmic rays and the
line-of-sight integrated gas content. Furthermore, the measured flux is higher
by a factor of than the prediction. A similar spectrum with an index of
is found in the outer Galaxy region, and the absolute flux for
TeV is again higher than the prediction for hadronic
cosmic ray interactions. The latitude distributions of the diffuse emission are
consistent with the gas distribution, while the longitude distributions show
clear deviation from the gas distribution. The LHAASO measurements imply that
either additional emission sources exist or cosmic ray intensities have spatial
variations.Comment: 12 pages, 8 figures, 5 tables; accepted for publication in Physical
Review Letters; source mask file provided as ancillary fil
On the Application of Situational Crime Prevention Theory to the Practice of Comprehensive Administration of Social Security
社会治安综合治理经过十几年的发展已成为具有中国特色的犯罪治理模式。但在实践中要如何突破“口号味浓、操作性难”的被动局面,是社会治安综合治理工作的当务之急。情境预防是近年来世界范围内犯罪预防的主流理论之一,其在西方国家取得的显著成效,使之与社会预防、司法预防鼎足而立。社会治安综合治理从宏观的角度入手,将预防措施逐步演绎至微观局面、大局观强;情境预防犯罪理论从微观的预防实践入手,将预防措施归纳成指导性的宏观原则、操作性强。笔者认为,在我国社会治安综合治理过程中借鉴情境预防犯罪理论,具有其特别的应用价值和现实意义。本文从探求情境预防犯罪理论在我国社会治安综合治理过程中的实践应用入手,应用大量实证事例...After years of development, the comprehensive administration of social security has become a crime control model with Chinese characteristics. However, as it is packed with slogans and difficult to operate, it is a priority to break though that passive situation in practice. Situational crime prevention is one of the mainstream theories on crime prevention throughout the world in recent years. Wit...学位:法律硕士院系专业:法学院法律系_法律硕士(JM)学号:X200512018
Establishment and assessments of a new model for the postoperative fatigue syndrome by major small intestinal resection in rats
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