417 research outputs found
The bulk Lorentz factors of Fermi-LAT GRBs
The Lorentz factor (LF) of gamma-ray burst (GRB) ejecta may be constrained by
observations of high-energy (HE) spectral attenuation. The recent Fermi-LAT
observations of prompt GeV emission from several bright GRBs have leaded to
conclusions of unexpectedly large LFs, . Here we revisit this
problem with two main concerns. (1) With one-zone assumption where all photons
are assumed to be generated in the same region (radius) and time, we {\em
self-consistently} calculate the optical depth by adopting a
target photon spectrum with HE cutoff. We find that this might be important
when the GRB LF is below a few hundreds. (2) Recent Fermi-LAT observations
suggest that the bulk MeV-range and HE (\ga100 MeV) emission may arise from
different regions. We then consider a two-zone case where HE emission is
generated in much larger radii than that of the MeV-range emission. We find
that the HE emission may be mainly attenuated by MeV-range emission and that
the attenuated HE spectrum does not show an exponential spectral cutoff but a
slight steepening. This suggests that there may be no abrupt cutoff due to
attenuation if relaxing the one-zone assumption. By studying the
spectra of three bright Fermi-LAT GRBs 080916C, 090510 and 090902B, we show
that a bulk LF of\textbf{ }can be consistent with observations
in the two-zone case. Even lower LFs can be obtained in the multi-zone case.Comment: 8 pages, a schematic figure added, the other 5 figures updated, ApJ,
in pres
A Case History of Ground Treatment for a Power Station in China
This paper presents a case history of ground treatment for a large power station - Zhang Ze Power Station, which locates in the south-east region in Shanxi, P. R. China. In the second phase of this project, a comprehensive treatment program including pile foundation, dynamic consolidation, and natural foundation has been used successfully according to significance of structure, conditions of loading, characters of technology, and so on. After 6 years working, the Station operates normally, and settlements of structures distribute well, proving the program is reasonable, workable, and economic. It is suggested that the choice of foundation treatment in a large project must consider comprehensively various factors, such as sorts of structure, types of loading, and geology in site, cost of construction, environment of site, etc
Microstructural deformation of clay
As far as is known, this is the first study to concentrate on the microstructural deformation of clay is undrained shear. The material was naturally dispersed; and it had been expected that during pre-peak deformation the platy clay particles would slip and turn to form large domains (i.e. groups of sub-parallel particles) inclined at 45o or more, although other hypotheses were also under consideration. Both optical microscopy and electron microscopy showed that the preferred orientation, which was originally horizontal, definitely remained horizontal whilst the shear strain increased, until the failure plane cut through the orientated structure.It was expected that when strongly anisotropic clay samples are deformed, the shear strain will disrupt the structure, so that the strength of anisotropy decreases. Conversely, when isotropic clay samples are deformed, it was expected that slippage of the particles will cause the strength of anisotropy to increase. The present samples started at a moderate strength of anisotropy, and the subsequent changes were small. This observation supports the above hypothesis and suggests that the examples were on the borderline between the two types of behaviour. There were, however, some changes of the microstructure. The strength of anisotropy at first appeared to increase and later to decrease as strain increased. The deviations of the orientations of the individual structural elements appeared to decrease at first and later to increase, this being the complementary trend. In addition, post-peak, the between-samples standard deviations increased with strain, suggesting that different samples were deforming in different ways.These results suggest that in normally consolidated undrained shear there may be three mechanisms acting within these samples, i.e. they were bedding down at first, and later being disrupted by the shear strains; but the failure plane cut through all pre-existing structure non-conformably. Further, there may have been an element of instability in the microstructural response to strain. The results available for the outer series of tests led to broadly similar conclusions.(Now derestricted
Development of a Work Zone Training Program
Safety in highway work zones has been a major concern for many decades. Over the years, government agencies and
highway industry have developed work zone safety training programs to educate general public, professionals, and
government employers. Existing training programs are conducted in the old fashion classroom setting which has some
disadvantages such as high travel costs and locations far away from jobs. The objective of this research project was to
develop a web-based training program for highway work zone safety. The developed program was built on advanced
computer science technologies and delivered via Internet so that a trainee can access the training materials at any time and
at any location as long as there is an Internet service. Training topics cover sign, marking, highway traffic signal, and
temporary traffic control. At the end of training, a trainee will have an opportunity to take an on-line quiz with 50
questions. A certificate will be sent to the trainee via e-mail if that personβs test score is higher than the passing grade.
The developed web-based training program has several advantages. First, using the developed program will eliminate the
travel costs for the instructors and trainees. Second, both the instructors and trainees will spend less time away from their
jobs. Third, the developed program can be easily modified and updated with any new information. Finally, trainees can
learn the training materials at their own pace. The self pace format can be easily fitted in a busy working schedule
Jet Sideways Expansion Effect on Estimating the Gamma-Ray Burst Efficiency
The high efficiency of converting kinetic energy into gamma-rays estimated
with late-time afterglows in Gamma-Ray Burst (GRB) phenomenon challenges the
commonly accepted internal-shock model. However, the efficiency is still highly
uncertain because it is sensitive to many effects. In this Letter we study the
sideways expansion effect of jets on estimating the efficiency. We find that
this effect is considerable, reducing the efficiency by a factor of
for typical parameters, when the afterglow data hr after the GRB
trigger are used to derive the kinetic energy. For a more dense circumburst
medium, this effect is more significant. As samples, taking this effect into
account, we specifically calculate the efficiency of two bursts whose
parameters were well constrained. Almost the same results are derived. This
suggests that the sideways expansion effect should be considered when the GRB
efficiency is estimated with the late afterglow data.Comment: 9pages, 2figures, ApJL, accepted, appearing in Vol 653 (2006, Dec.
10
A novel approach for sports injury risk prediction: based on time-series image encoding and deep learning
The rapid development of big data technology and artificial intelligence has provided a new perspective on sports injury prevention. Although data-driven algorithms have achieved some valuable results in the field of sports injury risk assessment, the lack of sufficient generalization of models and the inability to automate feature extraction have made it challenging to deploy research results in the real world. Therefore, this study attempts to build an injury risk prediction model using a combination of time-series image encoding and deep learning algorithms to address this issue better. This study used the time-series image encoding approach for feature construction to represent relationships between values at different moments, including Gramian Angular Summation Field (GASF), Gramian Angular Difference Field (GADF), Markov Transition Field (MTF), and Recurrence Plot (RP). Deep Convolutional Auto-Encoder (DCAE) learned the image-encoded data for representation to obtain features with good discrimination, and the classifier was performed using Deep Neural Network (DNN). The results from five repeated experiments show that the GASF-DCAE-DNN model is overall better in the training (AUC: 0.985 Β± 0.001, Gmean: 0.930 Β± 0.007, Sensitivity: 0.997 Β± 0.003, Specificity: 0.868 Β± 0.013) and test sets (AUC: 0.891 Β± 0.026, Gmean: 0.830 Β± 0.027, Sensitivity: 0.816 Β± 0.039, Specificity: 0.845 Β± 0.022), with good discriminative power, robustness, and generalization ability. Compared with the best model reported in the literature, the AUC, Gmean, Sensitivity, and Specificity of the GASF-DCAE-DNN model were higher by 23.9%, 27.5%, 39.7%, and 16.2%, respectively, which confirmed the validity and practicability of the model in injury risk prediction. In addition, differences in injury risk patterns between the training and test sets were identified through shapley additivity interpretation. It was also found that the training volume was an essential factor that affected injury risk prediction. The model proposed in this study provides a powerful injury risk prediction tool for future sports injury prevention practice
Genomic regions linked to alcohol consumption in the Framingham Heart Study
BACKGROUND: Pedigree, demographic, square-root transformed maximum alcohol (SRMAXAPD) and maximum cigarette (MAXCPD) consumption, and genome-wide scan data from the Framingham Heart Study (FHS) were used to investigate genetic factors that may affect alcohol and cigarette consumption in this population-based sample. RESULTS: A significant sister:sister correlation greater than spouse correlation was observed for MAXCPD only. Single-point sib-pair regression analysis provided nominal evidence for linkage of loci to both SRMAXAPD and MAXCPD consumption traits, with more significant evidence of linkage to SRMAXAPD than to MAXCPD. One genomic region, chr9q21.11, exhibits significant multi-point sib-pair regression to SRMAXAPD. CONCLUSION: SRMAXAPD exhibits greater evidence for genetic linkage than does MAXCPD in the FHS sample. Four regions of the genome exhibiting nominal evidence for linkage to SRMAXAPD in the FHS sample correspond to regions of the genome previously identified as linked to alcoholism or related traits in the family data set ascertained on individuals affected with alcohol dependence known as COGA
2-[(E)-2-(BenzylΒideneΒamino)ΒethΒyl]-3β²,6β²-bisΒ(diethylΒamino)ΒspiroΒ[isoindoline-1,9β²-xanthen]-3-one
In the title compound, C37H40N4O2, the xanthene and spiroΒlactam rings are almost planar, with r.m.s. deviations from the mean planes of 0.223β
(2) and 0.057β
(2)β
Γ
, respectively, and form a dihedral angle of 85.76β
(3)Β°. The dihedral angle between the xanthene mean plane and the benzene ring is 87.16β
(5)Β°. One of the two ethyl groups of one of the diethylΒamino groups is disordered over two sets of sites [0.76β
(1):0.24β
(1)]
Tourism-Related CO 2
The rapid development of the tourism industry has been accompanied by an increase in CO2 emissions and has a certain degree of impact on climate change. This study adopted the bottom-up approach to estimate the spatiotemporal change of CO2 emissions of the tourism industry in China and its 31 provinces over the period 2000β2015. In addition, the decoupling index was applied to analyze the decoupling effects between tourism-related CO2 emissions and tourism economy from 2000 to 2015. The results showed that the total CO2 emissions of the tourism industry rose from 37.95βMt in 2000 to 100.98βMt in 2015 with an average annual growth rate of 7.1%. The highest CO2 emissions from the tourism industry occurred in eastern coastal China, whereas the least CO2 emissions were in the west of China. Additionally, the decoupling of CO2 emissions from economic growth in Chinaβs tourism industry had mainly gone through the alternations of negative decoupling and weak decoupling. The decoupling states in most of the Chinese provinces were desirable during the study period. This study may serve as a scientific reference regarding decision-making in the sustainable development of the tourism industry in China
Ubiquitin-Specific Peptidase 10 (USP10) Deubiquitinates and Stabilizes MutS Homolog 2 (MSH2) to Regulate Cellular Sensitivity to DNA Damage
MSH2 is a key DNA mismatch repair protein, which plays an important role in genomic stability. In addition to its DNA repair function, MSH2 serves as a sensor for DNA base analogs-provoked DNA replication errors and binds to various DNA damage-induced adducts to trigger cell cycle arrest or apoptosis. Loss or depletion of MSH2 from cells renders resistance to certain DNA-damaging agents. Therefore, the level of MSH2 determines DNA damage response. Previous studies showed that the level of MSH2 protein is modulated by the ubiquitin-proteasome pathway, and histone deacetylase 6 (HDAC6) serves as an ubiquitin E3 ligase. However, the deubiquitinating enzymes, which regulate MSH2 remain unknown. Here we report that ubiquitin-specific peptidase 10 (USP10) interacts with and stabilizes MSH2. USP10 deubiquitinates MSH2 in vitro and in vivo. Moreover, the protein level of MSH2 is positively correlated with the USP10 protein level in a panel of lung cancer cell lines. Knockdown of USP10 in lung cancer cells exhibits increased cell survival and decreased apoptosis upon the treatment of DNA-methylating agent N-methyl-Nβ²-nitro-N-nitrosoguanidine (MNNG) and antimetabolite 6-thioguanine (6-TG). The above phenotypes can be rescued by ectopic expression of MSH2. In addition, knockdown of MSH2 decreases the cellular mismatch repair activity. Overall, our results suggest a novel USP10-MSH2 pathway regulating DNA damage response and DNA mismatch repair
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