48,166 research outputs found
Multiband Emission from Pulsar Wind Nebulae: A Possible Injection Spectrum
A recent research shows that particles with a spectrum of a relativistic
Maxwellian plus a high-energy tail can be accelerated by relativistic
collisionless shocks. We investigate the possibility of the high-energy
particles with this new spectrum injected in pulsar wind nebulae (PWNe) from
the terminate shock based on the study of multiwavelength emission from PWNe.}
{The dynamics of a supernova remnant (SNR) and multiband nonthermal emission
from the PWN inside the remnant are investigated using a dynamical model with
electrons/positrons injected with the new spectrum. In this model, the
dynamical and radiative evolution of a pulsar wind nebula in a non-radiative
supernova remnant can be self-consistently described.} {This model is applied
to the three composite SNRs, G0.9+0.1, MSH 15-52, G338.3-0.0, and the multiband
observed emission from the three PWNe can be well reproduced.} {Our studies on
the three remnant provide evidence for the new spectrum of the particles, which
are accelerated by the terminate shock, injected into a PWN.Comment: 9 pages, 9 figures, accepted by A&
Effective SU(2)_L x U(1) theory and the Higgs boson mass
We assume the stability of vacuum under radiative corrections in the context
of the standard electroweak theory. We find that this theory behaves as a good
effective model already at cut off energy scales as low as 0.7 TeV. This
stability criterion allows to predict m_H= 318 +- 13 GeV for the Higgs boson
mass.Comment: Latex, 5 pages, 1 Postscript figure include
Determination of and Extraction of from Semileptonic Decays
By globally analyzing all existing measured branching fractions and partial
rates in different four momentum transfer-squared bins of decays, we obtain the product of the form factor and magnitude of
CKM matrix element to be . With this
product, we determine the semileptonic form factor
in conjunction with the value of
determined from the SM global fit. Alternately, with the product together with
the input of the form factor calculated in lattice QCD recently, we
extract , where the error is
still dominated by the uncertainty of the form factor calculated in lattice
QCD. Combining the
extracted from all existing measurements of decays and
together, we find the most
precisely determined to be , which improves
the accuracy of the PDG'2014 value by
The radial abundance gradient of oxygen towards the Galactic anticentre
We present deep optical spectroscopy of eight HII regions located in the
anticentre of the Milky Way. The spectra were obtained at the 10.4m GTC and
8.2m VLT. We determined Te([NII]) for all objects and Te([OIII]) for six of
them. We also included in our analysis an additional sample of 13 inner-disc
Galactic Hii regions from the literature that have excellent T_e
determinations. We adopted the same methodology and atomic dataset to determine
the physical conditions and ionic abundances for both samples. We also detected
the CII and OII optical recombination lines in Sh 2-100, which enables
determination of the abundance discrepancy factor for this object. We found
that the slopes of the radial oxygen gradients defined by the HII regions from
R_25 (= 11.5 kpc) to 17 kpc and those within R_25 are similar within the
uncertainties, indicating the absence of flattening in the radial oxygen
gradient in the outer Milky Way. In general, we found that the scatter of the
O/H ratios of Hii regions is not substantially larger than the observational
uncertainties. The largest possible local inhomogeneities of the oxygen
abundances are of the order of 0.1 dex. We also found positive radial gradients
in Te([O III]) and Te([N II]) across the Galactic disc. The shapes of these
temperature gradients are similar and also consistent with the absence of
flattening of the metallicity distribution in the outer Galactic disc.Comment: 20 pages, 11 figures. Accepted for publication in Monthly Notices of
the Royal Astronomical Societ
A relativistic calculation of super-Hubble suppression of inflation with thermal dissipation
We investigated the evolution of the primordial density perturbations
produced by inflation with thermal dissipation. A full relativistic analysis on
the evolution of initial perturbations from the warm inflation era to a
radiation-dominated universe has been developed. The emphasis is on tracking
the ratio between the adiabatic and the isocurvature mode of the initial
perturbations. This result is employed to calculate a testable factor: the
super-Hubble suppression of the power spectrum of the primordial perturbations.
We show that based on the warm inflation scenario, the super-Hubble suppression
factor, , for an inflation with thermal dissipation is at least 0.5. This
prediction does not depend on the details of the model parameters. If is
larger than 0.5, it implies that the friction parameter is larger than
the Hubble expansion parameter during the inflation era.Comment: 22 pages, 3 figures, use RevTex, accepted by Class. Quant. Gra
The Economic Impact of the Nevada Clean Indoor Air Act in Clark County, Nevada – Preliminary Findings
Objective. The primary purpose of this exploratory study was to quantitatively evaluate the economic impact of the Nevada Clean Indoor Air Act (NCIAA) on businesses in Clark County.
Methods. The goal of this research was to assess economic indicators over a ten year period utilizing measurable data points, including restaurant and drinking establishment employment rates, taxable sales, openings and closings, as well as slot gaming revenues. This ten year time period consisted of a seven year span prior to the enactment of the NCIAA, and three years post enactment. Researchers conceived this study as a means to independently evaluate and address the potential economic impact of a smoke-free law in a region dependent upon tourism and gaming.
Results. Economic indicators did in fact decrease after the NCIAA was enforced but most of the declining trends began prior to the passage of the smoke-free act and are consistent with downward trends in other, non-NCIAA affected segments of our economy.
Conclusion. The overall findings of this study are consistent with similar non-tobacco industry supported economic studies showing little or no statistically significant downward economic trends after passage of smoke-free legislation
Fokker-Planck type equations with Sobolev diffusion coefficients and BV drift coefficients
In this paper we give an affirmative answer to an open question mentioned in
[Le Bris and Lions, Comm. Partial Differential Equations 33 (2008),
1272--1317], that is, we prove the well-posedness of the Fokker-Planck type
equations with Sobolev diffusion coefficients and BV drift coefficients.Comment: 11 pages. The proof has been modifie
The origin of scale-scale correlations of the density perturbations during inflation
We show that scale-scale correlations are a generic feature of slow-roll
inflation theories. These correlations result from the long-time tails
characteristic of the time dependent correlations because the long wavelength
density perturbation modes are diffusion-like. A relationship between the
scale-scale correlations and time-correlations is established providing a way
to reveal the time correlations of the perturbations during inflation. This
mechanism provides for a testable prediction that the scale-scale correlations
at two different spatial points will vanish.Comment: Accepted for publication, International Journal of Modern Physics,
vol. 8 No.6 (Dec 1999
Magnetotransport with two occupied subbands in a Si(100) inversion layer
We have studied an electron transport in inversion layers of high-mobility
Si(100) samples. At high electron concentrations and temperatures below 4.2 K,
two series of Shubnikov-de Haas oscillations have been observed. The
temperature damping of the second series oscillations indicates that the second
occupied subband belongs to the first energy level of the fourfold-degenerate
ladder . Samples with two occupied subbans exhibit a strong anomalous
negative magnetoresitance, reaching of a zero field value
at 12 T. The resistance decrease is more pronounced for lower
temperatures and higher electron concentrations. We explain this behaviour by
an increase of the second subband mobility due to the freezing-out of the
scattering of electrons. Based on the measured periods of SdH
oscillations, we conclude that the electrons are distributed inhomogeneously
beneath the sample gate.Comment: 4 pages. RevTex text and 4 PostScript figures in a single
tar-compressed file produced by 'uufiles
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