436 research outputs found
Analysis of Stress State of Bolts Under Different Anchorage Qualities
A series of pull-out tests were conducted in order to study the stress states of bolts under different anchorage qualities and to simulate the influence of quality defects in empty-slurry and low-strength mortar anchorage in actual engineering. The tests mainly investigated strain characteristics at different positions of the bolts and the effects of strains at the same positions under different anchorage conditions. The research led to the following conclusions: (1) under ultimate bearing capacity, the strain values decayed the fastest along the length of the bolt in the full-length anchorage, the strain values decayed the slowest in the empty-slurry and low-strength mortar anchorage, and the decaying speed of strains in the empty-slurry mortar anchorage was between that of the above two kinds of anchorages; (2) at almost 50% of the ultimate bearing capacity, the strain values were slightly different between the empty-slurry and low-strength mortar anchorage and the empty-slurry anchorage. Obvious differences in strain values occurred when the bolts were continued to be loaded. The strain values of the full-length anchorage bolts were different from those of the other two kinds of anchorages; (3) from the analysis of stress variation characteristics, the safety reserve was the highest for the full-length anchorage under the condition of ultimate bearing capacity, followed by the empty-slurry mortar anchorage, while the safety reserve was the lowest for the empty-slurry and low-strength mortar anchorage. However, in terms of uniformity of force and utilization of the material, the result was reverse
Self-organized Boolean game on networks
A model of Boolean game with only one free parameter that denotes the
strength of herd behavior is proposed where each agent acts according to the
information obtained from his neighbors in network and those in the minority
are rewarded. The simulation results indicate that the dynamic of system is
sensitive to network topology, where the network of larger degree variance,
i.e. the system of greater information heterogeneity, leads to less system
profit. The system can self-organize to a stable state and perform better than
random choice game, although only the local information is available to the
agents. In addition, in heterogeneity networks, the agents with more
information gain more than those with less information for a wide extent of
herd strength .Comment: 5 pages, 5 eps figure
Non-uniform Black Strings with Schwarzschild-(Anti-)de Sitter Foliation
We present some exact non-uniform black string solutions of 5-dimensional
pure Einstein gravity as well as Einstein-Maxwell-dilaton theory at arbitrary
dilaton coupling. The solutions share the common property that their
4-dimensional slices are Schwarzchild-(anti-)de Sitter spacetimes. The pure
gravity solution is also generalized to spacetimes of dimensions higher than 5
to get non-uniform black branes.Comment: LaTeX 14 pages, 3 eps figures. V2: version appeared in CQ
Full polar cap cascade scenario: -ray and X-ray luminosities from spin-powered pulsars
We modify polar cap cascade picture to include the ICS of the higher
generation pairs. In such a ``full-cascade'' scenario, not only the
perpendicular portion of the energy of the pairs goes to high energy radiation
via SR, but the parallel portion of the energy of the pairs can also contribute
to high energy emission via ICS with the soft thermal photons from either the
full neutron star surface or the hot polar cap. An important output of such a
scenario is that the soft tail of the ICS spectrum can naturally result in a
non-thermal X-ray component which can contribute to the luminosities observed
by ROSAT and ASCA. Here we present an analytic description of such a full polar
cap cascade scenario within the framework of Harding & Muslimov acceleration
model. We present the theoretical predictions of the -ray luminosities,
the thermal and non-thermal X-ray luminosities for the known spin-powered X-ray
pulsars. Our results show that the observed different dependences of the high
energy luminosities on the pulsar spin-down luminosities, i.e., and , are well
reproduced. Our model predicts that the {\em pulsed} soft X-rays in the ROSAT
band from most of the millisecond pulsars might be of thermal origin if there
is no strong multipole field components near the surfaces of these pulsars.Comment: 23 pages, emulateapj style, final version to appear in the
Astrophysical Journa
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Effect of transcutaneous auricular vagus nerve stimulation on impaired glucose tolerance: a pilot randomized study
Background: Impaired glucose tolerance (IGT) is a pre-diabetic state of hyperglycemia that is associated with insulin resistance, increased risk of type II diabetes, and cardiovascular pathology. Recently, investigators hypothesized that decreased vagus nerve activity may be the underlying mechanism of metabolic syndrome including obesity, elevated glucose levels, and high blood pressure. Methods: In this pilot randomized clinical trial, we compared the efficacy of transcutaneous auricular vagus nerve stimulation (taVNS) and sham taVNS on patients with IGT. 72 participants with IGT were single-blinded and were randomly allocated by computer-generated envelope to either taVNS or sham taVNS treatment groups. In addition, 30 IGT adults were recruited as a control population and not assigned treatment so as to monitor the natural fluctuation of glucose tolerance in IGT patients. All treatments were self-administered by the patients at home after training at the hospital. Patients were instructed to fill in a patient diary booklet each day to describe any side effects after each treatment. The treatment period was 12 weeks in duration. Baseline comparison between treatment and control group showed no difference in weight, BMI, or measures of systolic blood pressure, diastolic blood pressure, fasting plasma glucose (FPG), 2-hour plasma glucose (2hPG), or glycosylated hemoglobin (HbAlc). Results: 100 participants completed the study and were included in data analysis. Two female patients (one in the taVNS group, one in the sham taVNS group) dropped out of the study due to stimulation-evoked dizziness. The symptoms were relieved after stopping treatment. Compared with sham taVNS, taVNS significantly reduced the two-hour glucose tolerance (F(2) = 5.79, p = 0.004). In addition, we found that taVNS significantly decreased (F(1) = 4.21, p = 0.044) systolic blood pressure over time compared with sham taVNS. Compared with the no-treatment control group, patients receiving taVNS significantly differed in measures of FPG (F(2) = 10.62, p < 0.001), 2hPG F(2) = 25.18, p < 0.001) and HbAlc (F(1) = 12.79, p = 0.001) over the course of the 12 week treatment period. Conclusions: Our study suggests that taVNS is a promising, simple, and cost-effective treatment for IGT/ pre-diabetes with only slight risk of mild side-effects
Feasibility of quantum key distribution through dense wavelength division multiplexing network
In this paper, we study the feasibility of conducting quantum key
distribution (QKD) together with classical communication through the same
optical fiber by employing dense-wavelength-division-multiplexing (DWDM)
technology at telecom wavelength. The impact of the classical channels to the
quantum channel has been investigated for both QKD based on single photon
detection and QKD based on homodyne detection. Our studies show that the latter
can tolerate a much higher level of contamination from the classical channels
than the former. This is because the local oscillator used in the homodyne
detector acts as a "mode selector" which can suppress noise photons
effectively. We have performed simulations based on both the decoy BB84 QKD
protocol and the Gaussian modulated coherent state (GMCS) QKD protocol. While
the former cannot tolerate even one classical channel (with a power of 0dBm),
the latter can be multiplexed with 38 classical channels (0dBm power each
channel) and still has a secure distance around 10km. Preliminary experiment
has been conducted based on a 100MHz bandwidth homodyne detector.Comment: 18 pages, 5 figure
MICB0106 gene polymorphism is associated with ulcerative colitis in central China
Background: The highly polymorphic nonclassical MHC class I chain-related genes A and B (MICA and MICB) encode stress-inducible glycoproteins expressed on various epithelial cells including intestinal epithelial cells. MICA and MICB gene polymorphisms and expressions are associated with autoimmune diseases but not known in ulcerative colitis (UC). Aims: To investigate the association of MICB exon 2-4 polymorphisms and soluble MICA (sMICA) expression with the susceptibility of UC in central China. Materials and methods: Genomic DNA was isolated from peripheral blood. The allele frequencies of MICB exon 2-4 were genotyped in 105 UC patients and 213 healthy controls by PCR single-stranded conformation polymorphism method. Thirty-two patients and 32 controls were selected for determining serum sMICA expression by ELISA. Results: Allele frequency of MICB0106 was significantly higher in UC patients than in healthy controls (19.0% vs. 8.9%, corrected P (Pc)=0.0006), especially in patients with extensive colitis (24.4% vs. 8.9%, Pc=0.0006), moderate and severe disease (24.1% vs. 8.9%, Pc=0.0006), extraintestinal manifestations (20.5% vs. 8.9%, Pc=0.012), male patients (22.1% vs. 8.0%, Pc=0.006), and patients over the age of 40 years (28.8% vs. 8.3%, Pc=0.0006). The sMICA level was significantly higher in UC than in healthy controls (604.41±480.43 pg/ml vs. 175.37±28.31 pg/ml, P=0.0001) but not associated with the MICB0106 genotypes. Conclusions: Overall, MICB0106 allele was positively associated with UC in the Han Chinese in central China. sMICA was highly expressed in UC but not associated with the MICB0106 genotype
Cooperation of breast cancer proteins PALB2 and piccolo BRCA2 in stimulating homologous recombination.
Inherited mutations in human PALB2 are associated with a predisposition to breast and pancreatic cancers. PALB2's tumor-suppressing effect is thought to be based on its ability to facilitate BRCA2's function in homologous recombination. However, the biochemical properties of PALB2 are unknown. Here we show that human PALB2 binds DNA, preferentially D-loop structures, and directly interacts with the RAD51 recombinase to stimulate strand invasion, a vital step of homologous recombination. This stimulation occurs through reinforcing biochemical mechanisms, as PALB2 alleviates inhibition by RPA and stabilizes the RAD51 filament. Moreover, PALB2 can function synergistically with a BRCA2 chimera (termed piccolo, or piBRCA2) to further promote strand invasion. Finally, we show that PALB2-deficient cells are sensitive to PARP inhibitors. Our studies provide the first biochemical insights into PALB2's function with piBRCA2 as a mediator of homologous recombination in DNA double-strand break repair
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