158,944 research outputs found
Broadening, shifting, and line asymmetries in the 2â0 band of CO and COâN2: Experimental results and theoretical calculations
We have measured the room temperature, widths, pressure shifts, and line asymmetry coefficients for many transitions of the first overtone band of CO and CO perturbed by N2. role= presentation style= display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px 2px 0px 0px; margin: 0px; position: relative; \u3eN2.N2. The broadening coefficients were obtained with an accuracy of about 1%. The pure CO profiles have been fitted by a Voigt profile while the COâN2 role= presentation style= display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px 2px 0px 0px; margin: 0px; position: relative; \u3eCOâN2COâN2 spectral profiles have been fitted with a Lorentz and an empirical line shape model (HCv) role= presentation style= display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px 2px 0px 0px; margin: 0px; position: relative; \u3e(HCv)(HCv) that blends together a hard collision model and a speed-dependent Lorentz profile. In addition to the Voigt, Lorentz, and HCv role= presentation style= display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px 2px 0px 0px; margin: 0px; position: relative; \u3eHCvHCv models, we have added a dispersion profile to account for weak line mixing. The line broadening and shift coefficients are compared to semiclassical calculations employing a variety of intermolecular interactions.The line asymmetry results are compared to line mixing calculations based on the energy corrected sudden (ECS) model.The results indicate that effects other than line mixing also contribute to the measured line asymmetry
The Subaru HSC weak lensing mass-observable scaling relations of spectroscopic galaxy groups from the GAMA survey
We utilize the galaxy shape catalogue from the first-year data release of the Subaru Hyper Suprime-Cam (HSC) survey to study the dark matter content of galaxy groups in the Universe using weak lensing. We use galaxy groups from the Galaxy Mass and Assembly galaxy survey in approximately 100 sq. degrees of the sky that overlap with the HSC survey as lenses. We restrict our analysis to the 1587 groups with at least five members. We divide these groups into six bins each of group luminosity and group member velocity dispersion and measure the lensing signal with a signal-to-noise ratio of 55 and 51 for these two different selections, respectively. We use a Bayesian halo model framework to infer the halo mass distribution of our groups binned in the two different observable properties and constrain the power-law scaling relation and the scatter between mean halo masses and the two-group observable properties. We obtain a 5 perâcent constraint on the amplitude of the scaling relation between halo mass and group luminosity with â©MâȘ = (0.81 ± 0.04) Ă 1014 hâ1 Mâ for Lgrp = 1011.5 hâ2 Lâ, and a power-law index of α = 1.01 ± 0.07. We constrain the amplitude of the scaling relation between halo mass and velocity dispersion to be â©MâȘ = (0.93 ± 0.05) Ă 1014 hâ1 Mâ for Ï=500kmsâ1 role= presentation style= box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; font-variant: inherit; font-stretch: inherit; line-height: normal; font-family: inherit; vertical-align: baseline; display: inline; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; position: relative; \u3eÏ=500kmsâ1Ï=500kmsâ1 and a power-law index to be α = 1.52 ± 0.10. However, these scaling relations are sensitive to the exact cuts applied to the number of group members. Comparisons with similar scaling relations from the literature show that our results are consistent and have significantly reduced errors
Robust and clean Majorana zero mode in the vortex core of high-temperature superconductor (Li0.84Fe0.16)OHFeSe
The Majorana fermion, which is its own anti-particle and obeys non-abelian
statistics, plays a critical role in topological quantum computing. It can be
realized as a bound state at zero energy, called a Majorana zero mode (MZM), in
the vortex core of a topological superconductor, or at the ends of a nanowire
when both superconductivity and strong spin orbital coupling are present. A MZM
can be detected as a zero-bias conductance peak (ZBCP) in tunneling
spectroscopy. However, in practice, clean and robust MZMs have not been
realized in the vortices of a superconductor, due to contamination from
impurity states or other closely-packed Caroli-de Gennes-Matricon (CdGM)
states, which hampers further manipulations of Majorana fermions. Here using
scanning tunneling spectroscopy, we show that a ZBCP well separated from the
other discrete CdGM states exists ubiquitously in the cores of free vortices in
the defect free regions of (Li0.84Fe0.16)OHFeSe, which has a superconducting
transition temperature of 42 K. Moreover, a Dirac-cone-type surface state is
observed by angle-resolved photoemission spectroscopy, and its topological
nature is confirmed by band calculations. The observed ZBCP can be naturally
attributed to a MZM arising from this chiral topological surface states of a
bulk superconductor. (Li0.84Fe0.16)OHFeSe thus provides an ideal platform for
studying MZMs and topological quantum computing.Comment: 32 pages, 15 figures (supplementary materials included), accepted by
PR
PAIRWISE VELOCITIES OF GALAXIES IN THE CFA AND SSRS2 REDSHIFT SURVEYS
(compressed version) We combine the CfA Redshift Survey (CfA2) and the
Southern Sky Redshift Survey (SSRS2) to estimate the pairwise velocity
dispersion of galaxies \sig12 on a scale of \sim 1 \hmpc. Both surveys are
complete to an apparent magnitude limit . Our sample includes 12,812
galaxies distributed in a volume 1.8 \times 10^6 \hmpc3. We conclude: 1) The
pairwise velocity dispersion of galaxies in the combined CfA2+SSRS2 redshift
survey is \sig12=540 \kms \pm 180 \kms. Both the estimate and the variance of
\sig12 significantly exceed the canonical values \sig12=340 \pm40 measured
by Davis \& Peebles (1983) using CfA1. 2) We derive the uncertainty in \sig12
from the variation among subsamples with volumes on the order of \hmpc3. This variation is nearly an order of magnitude larger than the
formal error, 36 \kms, derived using least-squares fits to the CfA2+SSRS2
correlation function. This variation among samples is consistent with the
conclusions of Mo \etal (1993) for a number of smaller surveys and with the
analysis of CfA1 by Zurek \etal (1994). 3) When we remove Abell clusters with
from our sample, the pairwise velocity dispersion of the remaining
galaxies drops to 295 \pm 99 \kms. Thus the dominant source of variance in
\sig12 is the shot noise contributed by dense virialized systems. 4) The
distribution of pairwise velocities is consistent with an isotropic exponential
with velocity dispersion independent of scale.Comment: 61 pages uuencoded, compressed postscript in 5 pieces. Also available
in one piece at http://www.dao.nrc.ca/DAO/SCIENCE/science.htm
P Wave Dispersion is Increased in Pulmonary Stenosis
Aim: The right atrium pressure load is increased in pulmonary stenosis (PS) that is a congenital anomaly and this changes the electrophysiological characteristics of the atria. However, there is not enough data on the issue of P wave dispersion (PWD) in PS.
Methods: Forty- two patients diagnosed as having valvular PS with echocardiography and 33 completely healthy individuals as the control group were included in the study. P wave duration, p wave maximum (p max) and p minimum (p min) were calculated from resting electrocariography (ECG) obtained at the rate of 50 mm/sec. P wave dispersion was derived by subtracting p min from p max. The mean pressure gradient (MPG) at the pulmonary valve, structure of the valve and diameters of the right and left atria were measured with echocardiography. The data from two groups were compared with the Mann-Whitney U test and correlation analysis was performed with the Pearson correlation technique.
Results: There wasnât any statistically significance in the comparison of age, left atrial diameter and p min between two groups. While the MPG at the pulmonary valve was 43.11 ± 18.8 mmHg in PS patients, it was 8.4 ± 4.5 mmHg in the control group. While p max was 107.1 ± 11.5 in PS group, it was 98.2 ± 5.1 in control group (p=0.01), PWD was 40.4 ± 1.2 in PS group, and 27.2 ± 9.3 in the control group (p=0.01)Moreover, while the diameter of the right atrium in PS group was greater than that of the control group, (38.7 ± 3.9 vs 30.2 ± 2.5, p=0.02). We detected a correlation between PWD and pressure gradient in regression analysis.
Conclusion: P wave dispersion and p max are increased in PS. While PWD was correlated with the pressure gradient that is the degree of narrowing, it was not correlated with the diameters of the right and left atria
Thickening of galactic disks through clustered star formation
(Abridged) The building blocks of galaxies are star clusters. These form with
low-star formation efficiencies and, consequently, loose a large part of their
stars that expand outwards once the residual gas is expelled by the action of
the massive stars. Massive star clusters may thus add kinematically hot
components to galactic field populations. This kinematical imprint on the
stellar distribution function is estimated here by calculating the velocity
distribution function for ensembles of star-clusters distributed as power-law
or log-normal initial cluster mass functions (ICMFs). The resulting stellar
velocity distribution function is non-Gaussian and may be interpreted as being
composed of multiple kinematical sub-populations. The notion that the formation
of star-clusters may add hot kinematical components to a galaxy is applied to
the age--velocity-dispersion relation of the Milky Way disk to study the
implied history of clustered star formation, with an emphasis on the possible
origin of the thick disk.Comment: MNRAS, accepted, 27 pages, 9 figure
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