Search results for "PROFILE"
showing 10 items of 915 documents
Pressure Shift and Gravitational Red Shift of Balmer Lines in White Dwarfs. Rediscussion
2015
The Stark-induced shift and asymmetry, the so-called pressure shift (PS) of $H_\alpha$ and $H_\beta$ Balmer lines in spectra of DA white dwarfs (WDs), as masking effects in measurements of the gravitational red shift in WDs, have been examined in detail. The results are compared with our earlier ones from before a quarter of a century (Grabowski et al. 1987, hereafter ApJ'87; Madej and Grabowski 1990). In these earlier papers, as a dominant constituent of the Balmer-line-profiles, the standard, symmetrical Stark line profiles, shifted as the whole by PS-effect, were applied to all spectrally active layers of the WD atmosphere. At present, in each of the WD layers, the Stark-line-profiles (e…
The Gaia-ESO Survey: Catalogue of Hα emission stars
2015
We discuss the properties of Hα emission stars across the sample of 22035 spectra from the Gaia-ESO Survey internal data release, observed with the GIRAFFE instrument and largely belonging to stars in young open clusters. Automated fits using two independent Gaussian profiles and a third component that accounts for the nebular emission allow us to discern distinct morphological types of Hα line profiles with the introduction of a simplified classification scheme. All in all, we find 3765 stars with intrinsic emission and sort their spectra into eight distinct morphological categories: single-component emission, emission blend, sharp emission peaks, double emission, P-Cygni, inverted P-Cygni…
GRB 070311: a direct link between the prompt emission and the afterglow
2007
We present prompt gamma-ray, early NIR/optical, late optical and X-ray observations of the peculiar GRB 070311 discovered by INTEGRAL, in order to gain clues on the mechanisms responsible for the prompt gamma-ray pulse as well as for the early and late multi-band afterglow of GRB 070311. We fitted with empirical functions the gamma-ray and optical light curves and scaled the result to the late time X-rays. The H-band light curve taken by REM shows two pulses peaking 80 and 140 s after the peak of the gamma-ray burst and possibly accompanied by a faint gamma-ray tail. Remarkably, the late optical and X-ray afterglow underwent a major rebrightening between 3x10^4 and 2x10^5 s after the burst …
Inverse photonic-crystal-fiber design through geometrical and material scalings
2020
Geometrical and material - i.e., external and internal - scaling symmetries are exploited to obtain approximated analytical expressions for the mode effective index, group index, and chromatic dispersion of a scaled fiber. Our results include material refractive index scaling that changes the numerical aperture. First, the analytical expressions are successfully tested with a conventional step index fiber in a broadband range of wavelengths, from 1 to 2 mu m. Then, we establish a procedure to adapt the analytical expressions to photonic crystal fibers (PCFs) and illustrate its application in a triangular PCF with circular holes. These adapted analytical expressions show good agreement with …
A relativistically broadened iron line from an Accreting Millisecond Pulsar
2010
The capabilities of XMM-Newton have been fully exploited to detect a broadened iron Kα emission line from the 2.5 ms Accreting Millisecond Pulsar, SAX J1808.4-3658. The energy of the transition is compatible with fluorescence from neutral/lowly ionized iron. The observed large width (FWHM more than 1 keV) can be explained through Doppler and relativistic broadening from the inner rings of an accretion disc close to the NS. From a fit of the line shape with a diskline model we obtain an estimate of the inner disc radius of 18.0-5.6+7.6km for a 1.4 M⊙ neutron star. The disc is therefore truncated inside the corotation radius (31 km for SAX J1808.4-3658), in agreement with the observation of c…
Entropic approach to estimate the mean flow velocity: experimental investigation in laboratory flumes
2015
The paper deals with the linear entropic relationship between the maximum velocity, u max , and the mean flow velocity, u m , through a dimensionless parameter Φ(M), in open-channel flow. The analysis is conducted with the aid of experimental data collected in straight laboratory flumes under different bed and side-walls roughness conditions. In particular, rough/vegetated beds and smooth/rough side-walls conditions have been investigated. The results show that, in the investigated conditions (with exception of low-submergence vegetated bed—h/k v < 2), Φ(M) can be assumed equal to a value that is very close to that found in natural channels. This demonstrates that Φ(M) is able to implicitl…
Influence of distinct tool pin geometries on aluminum 8090 FSW joint properties
2023
Abstract. Aluminum Lithium alloys are recuperating substantial interest from automotive and aerospace industries owing to their extraordinary specific strength as compared to conventional aluminum (2xxx, 6xxx, and 7xxx) alloys. The goal of the present investigation is to study AA 8090 joints produced with the unique solid-state welding technique friction stir welding (FSW). Tool pin profile induces remarkable influence on friction and further plastic deformation during FSW. Therefrom, the influences of three distinct but constant dynamic area conditioned tool pin geometries namely, square trapezoidal, hexagonal trapezoidal, and threaded taper on the resulting material flow patterns, mechani…
Numerical simulations of air pollutant dispersion in a stratified planetary boundary layer
1978
Abstract A numerical model is described for computing pollutant concentration distributions downwind from a source. It is based on the three-dimensional dispersion equation governing the time-dependent advective and diffusive transport of air pollutants and is solved numerically by a mixed Lagrangian-Eulerian finite-difference scheme. The model includes the vertical wind shear, the turning of the actual wind, and vertical variations of the vertical eddy diffusivity. In this paper the model is used to simulate the pollutant dispersion process in a stratified planetary boundary layer. The vertical profiles of horizontal mean wind and vertical eddy diffusivities are calculated numerically from…
ICTV Virus Taxonomy Profile: Polycipiviridae
2019
Polycipiviridae is a family of picorna-like viruses with non-segmented, linear, positive-sense RNA genomes of approximately 10–12 kb. Unusually for viruses within the order Picornavirales, their genomes are polycistronic, with four (or more) consecutive 5′-proximal open reading frames (ORFs) encoding structural (and possibly other) proteins and a long 3′ ORF encoding the replication polyprotein. Members of species within the family have all been detected in ants or via arthropod transcriptomic datasets. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the Polycipiviridae, which is available at www.ictv.global/report/polycipiviridae.
Does a specific genetic background influence endurance or power-orientated phenotypes?
2012
The purpose of this study was to determine the probability of individuals having the “best” mitochondrial biogenesis related polygenic profile that could increase performance. We compared polygenic profile analyzing several polymorphisms on sixty professional italian soccer players, considered “power-oriented athletes” and thirty sedentary volunteers. Samples of venous blood were obtained by standard clinical procedures and anticoagulant-treated blood was used to prepare genomic DNA. The polymorphic sites were scanned using PCR-RFLP protocols with different enzyme. Furthermore, a cloted part of venus blood sample was used to obtain serum from which we analyzed total cholesterol, high densit…