794 research outputs found
Characteristics of profiles of gamma-ray burst pulses associated with the Doppler effect of fireballs
In this paper, we derive in a much detail the formula of count rates, in
terms of the integral of time, of gamma-ray bursts in the framework of
fireballs, where the Doppler effect of the expanding fireball surface is the
key factor to be concerned. Effects arising from the limit of the time delay
due to the limited regions of the emitting areas in the fireball surface and
other factors are investigated. Our analysis shows that the formula of the
count rate of fireballs can be expressed as a function of which is the
observation time scale relative to the dynamical time scale of the fireball.
The profile of light curves of fireballs depends only on the relative time
scale, entirely independent of the real time scale and the real size of the
objects. It displays in detail how a cutoff tail, or a turn over, feature
(called a cutoff tail problem) in the decay phase of a light curve can be
formed. This feature is a consequence of a hot spot in the fireball surface,
moving towards the observer, and was observed in a few cases previously. By
performing fits to the count rate light curves of six sample sources, we show
how to obtain some physical parameters from the observed profile of the count
rate of GRBs. In addition, the analysis reveals that the Doppler effect of
fireballs could lead to a power law relationship between the of pulses
and energy, which were observed previously by many authors.Comment: 38 pages, 10 figures; accepted for publication in ApJ (10 December
2004, v617
How much should I invest? The influence of reputable investors and platform investors in online lending
This paper draws on signaling theory to examine the joint effects of platform investment and investment of reputable investors on the investment behavior of ordinary investors in online lending. We tested our hypotheses with a dataset of 2,276,380 bidding records pertaining to 46,140 loans posted on an online lending platform. Our results show that (1) The investment of reputable investors as a quality signal can increase the investment amount of subsequent investors. (2) Platform investment signal and reputable investment signal are complementary. In the loan projects with platform investment (compared to those without), investment of reputable investors exerts greater influence on the investment amount of subsequent investors. (3) Focusing on loan projects with platform investment, the investment of reputable investors has greater impact on the investment amount of subsequent investors after the platform investment. This paper offers important theoretical and practical implications
Method of determining cosmological parameter ranges with samples of candles with an intrinsic distribution
In this paper, the effect of the intrinsic distribution of cosmological
candles is investigated. We find that, in the case of a narrow distribution,
the deviation of the observed modulus of sources from the expected central
value could be estimated within a ceratin range. We thus introduce a lower and
upper limits of , and , to
estimate cosmological parameters by applying the conventional minimizing method. We apply this method to a gamma-ray burst (GRB) sample as well as
to a combined sample including this GRB sample and an SN Ia sample. Our
analysis shows that: a) in the case of assuming an intrinsic distribution of
candles of the GRB sample, the effect of the distribution is obvious and should
not be neglected; b) taking into account this effect would lead to a poorer
constraint of the cosmological parameter ranges. The analysis suggests that in
the attempt of constraining the cosmological model with current GRB samples,
the results tend to be worse than what previously thought if the mentioned
intrinsic distribution does exist.Comment: 6 pages,4 figures,1 tables.Data updated. Main conclusion unchange
ANALYSIS OF FACTORS CAUSING WATER DAMAGE TO LOESS DOUBLE-ARCHED TUNNEL BASED ON TFN-AHP
In order to analysis the factors causing water damage to loess double-arched tunnel, this paper conducts field investigation on water damage to tunnels on Lishi-Jundu Expressway in Shanxi, China, confirms its development characteristics, builds an index system (covering 36 evaluation indexes for construction condition, design stage, construction stage, and operation stage) for the factors causing water damage to loess double-arched tunnel, applies TFN-AHP (triangular fuzzy number-analytic hierarchy process) in calculating the weight of indexes at different levels, and obtains the final sequence of weight of the factors causing water seepage to loess double-arched tunnel. It is found out that water damage to loess double-arched tunnel always develops in construction joints, expansion joints, settlement joints, and lining joints of tunnel and even around them; there is dotted water seepage, linear water seepage, and planar water seepage according to the trace and scope of water damage to tunnel lining. The result shows that water damage to loess double-arched tunnel mainly refers to linear water seepage, planar water seepage is also developed well, and partition and equipment box at the entrance and exit of tunnel are prone to water seepage; construction stage is crucial for controlling water damage to loess double-arched tunnel, atmospheric precipitation is the main water source, and the structure defect of double-arched tunnel increases the possibility of water seepage; the final sequence for weight of various factors is similar to the actual result
Magnetoelectric effects and valley controlled spin quantum gates in transition metal dichalcogenide bilayers
In monolayer group-VI transition metal dichalcogenides (TMDC), charge
carriers have spin and valley degrees of freedom, both associated with magnetic
moments. On the other hand, the layer degree of freedom in multilayers is
associated with electrical polarization. Here, we show that TMDC bilayers offer
an unprecedented platform to realize a strong coupling between the spin, layer
pseudospin, and valley degrees of freedom of holes. Such coupling not only
gives rise to the spin Hall effect and spin circular dichroism in inversion
symmetric bilayer, but also leads to a variety of magnetoelectric effects
permitting quantum manipulation of these electronic degrees of freedom.
Oscillating electric and magnetic fields can both drive the hole spin resonance
where the two fields have valley-dependent interference, making possible a
prototype interplay between the spin and valley as information carriers for
potential valley-spintronic applications. We show how to realize quantum gates
on the spin qubit controlled by the valley bit.Comment: 15 pages, 1 table, 4 figure
Sexually dimorphic genetic architecture of complex traits in a large-scale F2 cross in pigs
BACKGROUND: It is common for humans and model organisms to exhibit sexual dimorphism in a variety of complex traits. However, this phenomenon has rarely been explored in pigs. RESULTS: To investigate the genetic contribution to sexual dimorphism in complex traits in pigs, we conducted a sex-stratified analysis on 213 traits measured in 921 individuals produced by a White Duroc × Erhualian F(2) cross. Of the 213 traits examined, 102 differed significantly between the two sexes (q value <0.05), which indicates that sex is an important factor that influences a broad range of traits in pigs. We compared the estimated heritability of these 213 traits between males and females. In particular, we found that traits related to meat quality and fatty acid composition were significantly different between the two sexes, which shows that genetic factors contribute to variation in sexual dimorphic traits. Next, we performed a genome-wide association study (GWAS) in males and females separately; this approach allowed us to identify 13.6% more significant trait-SNP (single nucleotide polymorphism) associations compared to the number of associations identified in a GWAS that included both males and females. By comparing the allelic effects of SNPs in the two sexes, we identified 43 significant sexually dimorphic SNPs that were associated with 22 traits; 41 of these 43 loci were autosomal. The most significant sexually dimorphic loci were found to be associated with muscle hue angle and Minolta a* values (which are parameters that reflect the redness of meat) and were located between 9.3 and 10.7 Mb on chromosome 6. A nearby gene i.e. NUDT7 that plays an important role in heme synthesis is a strong candidate gene. CONCLUSIONS: This study illustrates that sex is an important factor that influences phenotypic values and modifies the effects of the genetic variants that underlie complex traits in pigs; it also emphasizes the importance of stratifying by sex when performing GWAS. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12711-014-0076-2) contains supplementary material, which is available to authorized users
3-(2-Bromophenyl)thiazolo[3,2-a]benzimidazole
The title compound, C15H9BrN2S, was prepared by the reaction of 1-bromo-2-(2,2-dibromovinyl)benzene with 1H-benzo[d]imidazole-2(3H)-thione. The thiazolo[3,2-a]benzimidazole fused-ring system is nearly planar, the maximum atomic deviation being 0.049 (4) Å. This mean plane is oriented at a dihedral angle of 71.55 (17)° with respect ot the bromophenyl ring. π–π stacking is observed in the crystal structure, the centroid–centroid distance between the thiazole and imidazole rings of adjacent molecules being 3.582 (2) Å
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