On deadlock detection in distributed computing systems

With the advent of distributed computing systems, the problem of deadlock, which has been essentially solved for centralized computing systems, has reappeared. Existing centralized deadlock detection techniques are either too expensive or they do not work correctly in distributed computing systems. Although several algorithms have been developed specifically for distributed systems, the majority of them have also been shown to be inefficient or incorrect. A new algorithm is proposed which is more efficient than any existing distributed deadlock detection algorithm. (Author)supported in part by the Foundation Research Program of the Naval Postgraduate School with funds provided the by Chief of Naval Researchhttp://archive.org/details/ondeadlockdetect00badaApproved for public release; distribution is unlimited

Automatic first-arrival picking method based on an image connectivity algorithm and multiple time windows

The use of a computer to automatically pick the first-arrival of a seismic signal is an operation that involves picking and screening the first arrival of the wave according to the criteria established in the manual picking process. To increase the picking accuracy for data with low-to-moderate signal-to-noise ratio (SNR), we propose a new single-trace boundary detection algorithm. This algorithm includes three steps: (1) calculate the first-arrival characteristic values through multi time windows; (2) take the times corresponding to the maximum characteristic values given by different time windows as intermediate results; (3) compare the intermediate results: if the difference is too large, it is marked the time is abnormal, otherwise the average time of the intermediate results is taken as the first-arrival time. Using this energy boundary detection method, the characteristic values obtained are bi-directionally expanded to allow the use of the trace connectivity algorithm which is improved from the region growing method. Determining the connectivity between the first-arrival characteristic values is a way to simulate how the human eye discriminates true first arrivals. This method significantly improves the elimination of false or abnormal first-arrivals. Next, a small-step fitting algorithm is applied to the remaining first-arrival characteristic values to complete the calculation of the final characteristic values. Based on the retained first-arrival characteristic values, the missing values are assigned by interpolation. The characteristic values are mapped on the original record and finally the first-arrival picking is completed using a small time window. Theoretical results as well as the results obtained from real data demonstrate that the proposed automatic first-arrival picking method effectively improves the accuracy of the first-arrival picking. Finally, the new picking algorithm is presented more efficient than the energy ratio method, as well as cross-correlation method

Spatial distribution of atoms in gas-covered Pd-X nanoparticles (X= Ag, Cu, Ni, Pt)

A Monte-carlo (MC) simulation procedure has been developed where the pair bond energies are allowed to take into account the various coordination numbers of surface atoms and the presence of adsorbates. The pair bond energies are calculated from partial bond energies of atoms which, in turn, are calculated from modified tight binding model in the second moment approximation. The model has been applied to study the role of adsorption of hydrogen, oxygen, carbon monoxide and nitric oxide on the surface composition and surface bond geometry of bimetallic Pd-X (X = Ag, Cu, Ni, Pt) nanoparticles having fcc cubo-octahedral geometry with 201, 586, 1289 and 2406 atoms. The results are compared with the known experimental results. Importance of the results in studying reactions on supported bimetallic catalysts has been highlighted.Comment: 15 pages (Latex) + 38 figures (eps

Lithospheric dynamics in the vicinity of the Tengchong volcanic field (southeastern margin of Tibet): An investigation using P receiver functions

Tengchong volcanic field (TVF) in the northern Indochina block lies in a critical area for understanding complex regional dynamics associated with continent-continent convergence between the Indian and Eurasian plates, including northeastward compression generated by subduction of the Indian Plate beneath the Burma Arc, and southeastward lateral extrusion of the crust from below central Tibet. We gathered 3408 pairs of P receiver functions with different frequencies and calculated the splitting parameters of the Moho-converted Pms phase. An anisotropic H-¿ stacking algorithm was used to determine crustal thickness and Vp/Vs ratios. We also inverted for the detailed S-velocity structure of the crust and upper mantle using a two-step inversion technique. Finally, we mapped the topography of the lithosphere-asthenosphere boundary. Results show fast-wave polarization directions with a dominant NE-SW orientation and delay times varying between 0.19 and 1.22 s, with a mean of 0.48 ± 0.07 s. The crustal Vp/Vs ratio varies from 1.68 to 1.90 and shows a maximum value below the central part of the TVF, where there is relatively thin crust (~35-39 km) and a pronounced low-velocity anomaly in the middle-lower crust. The depth of the lithosphere-asthenosphere boundary ranges from 53 to 85 km: it is relatively deep (~70-85 km) in the vicinity of the TVF and relatively shallow in the south of the study area. In the absence of low shear wave velocity in the upper mantle below the TVF, we propose that the low-velocity anomaly in the lower crust beneath the TVF derives from the upper mantle below the neighbouring Baoshan block

Decoding the Emeishan Permian mantle plume in the southeastern margin of Tibet from the seismic signature of the local lithosphere

The Emeishan large igneous province (ELIP), which is located along the southeastern margin of Tibet, is widely regarded as the erosional remnants of voluminous Permian mafic volcanic successions that were associated with mantle plume activity. In addition, evidence for the eruption of the mantle plume and its signature of lithospheric modification should have been retained in the lithosphere after cooling of the plume. Here we use calculated compressional- and shear wave receiver functions (PRFs and SRFs, respectively) from >750 broad-band stations, together with heat flow and Bouguer gravity anomaly data, to investigate the seismic signature within the lithosphere beneath the southeastern margin of Tibet. Our results from the inner zone (INZ) of the ELIP indicate that the ∼60 km depth of the Moho interpreted from depth-migrated PRF images is consistent with that inferred from SRFs and is deeper than that in the region surrounding the INZ, which shows a continuous positive converted phase at ∼35–40 km depth. The crustal geometry and physical properties show a 15–20-km-thick mafic underplated layer that extends for 150–200 km in the E–W direction and ∼400 km in the N–S direction along the base of the crust in the northeastern INZ and its surrounding region. We interpret the underplated layer as the concealed Emeishan plume hotspot track and suggest that the head of the postulated mantle plume is centred approximately beneath Panzhihua City and its surroundings. We propose a new geodynamic model for the formation of the ELIP, in which the lower–middle crust has been strengthened by voluminous mafic intrusions and underplating, whereas the Yangtze Craton in the plume region has been destroyed by removing the base of the lithosphere

Text Mining for Protein Docking

The rapidly growing amount of publicly available information from biomedical research is readily accessible on the Internet, providing a powerful resource for predictive biomolecular modeling. The accumulated data on experimentally determined structures transformed structure prediction of proteins and protein complexes. Instead of exploring the enormous search space, predictive tools can simply proceed to the solution based on similarity to the existing, previously determined structures. A similar major paradigm shift is emerging due to the rapidly expanding amount of information, other than experimentally determined structures, which still can be used as constraints in biomolecular structure prediction. Automated text mining has been widely used in recreating protein interaction networks, as well as in detecting small ligand binding sites on protein structures. Combining and expanding these two well-developed areas of research, we applied the text mining to structural modeling of protein-protein complexes (protein docking). Protein docking can be significantly improved when constraints on the docking mode are available. We developed a procedure that retrieves published abstracts on a specific protein-protein interaction and extracts information relevant to docking. The procedure was assessed on protein complexes from Dockground (http://dockground.compbio.ku.edu). The results show that correct information on binding residues can be extracted for about half of the complexes. The amount of irrelevant information was reduced by conceptual analysis of a subset of the retrieved abstracts, based on the bag-of-words (features) approach. Support Vector Machine models were trained and validated on the subset. The remaining abstracts were filtered by the best-performing models, which decreased the irrelevant information for ~ 25% complexes in the dataset. The extracted constraints were incorporated in the docking protocol and tested on the Dockground unbound benchmark set, significantly increasing the docking success rate

Inversion of surface wave phase velocities in a slightly a nisotropic medium

Inversion of surface wave velocities in examples of multilayered anisotropic media is examined using an extension of the Smith-Dahlen formulation. Thus, surface wave propagation in a slightly anisotropic earth model has been found and the inversion of the azimuthal dependence of surface wave dispersion curves has been performed. The inversion scheme proposed in this paper has been verified by numerical matrix inversion with a computer programme in FORTRAN code. In two examples, hexagonal simmetry and 13 non zero canonical harmonic components, we have got results that show an excellent agreement between all phase velocities obtained for both Love and Rayleigh waves. We also perform two additional experiments with observed data, Love and Rayleigh waves phase velocities results of previous studies carry out in the Pacific (Nishimura & Forsyth, 1985, 1988, 1989). In these data test we also have a good agreement between observed and theoretical data

Wave equation-based reflection tomography of the 1992 Landers earthquake area

In the framework of a recent wave equation-based traveltime seismic tomography, we show that incorporating Moho-reflected phases (PmP and SmS) in addition to the direct P and S phases can significantly increase tomography resolution in the lower crust and this may provide additional evidence to resolve important tectonic issues. To highlight the resolving power of the new strategy, we apply it in the region around the 1992 Landers earthquake (Mw = 7.3) in Southern California using seismic arrivals from local earthquakes, obtaining 3-D high-resolution P and S wave crustal velocity models and Poisson''s ratio structures. In the upper crust, our method confirmed features that had been previously found. However, in the middle-to-lower crust, we found low-velocity anomalies on the southeastern section of the San Jacinto Fault and high Vp and low Vs structures to the west of the Big Bear earthquake, which may be related to upwelling of partial melt from the mantle

Thrombin is a novel regulator of hexokinase activity in mesangial cells

Thrombin is a novel regulator of hexokinase activity in mesangial cells.BackgroundHexokinase (HK) activity is fundamentally important to cellular glucose uptake and metabolism. Phorbol esters increase both HK activity and glucose utilization in cultured mesangial cells via a protein kinase C (PKC)- and extracellular signal-regulated kinases 1 and 2 (ERK1/2)-dependent mechanism. In adult kidneys, increased HK activity has been reported in both glomerular injury and in diabetes, but the mechanisms responsible for these changes are unknown. Thrombin, a known activator of both PKC and ERK1/2, is increased in the settings of renal injury and diabetes. Thus, thrombin may contribute to the observed changes in HK activity in vivo.MethodsThrombin and thrombin receptor agonists were tested for the ability to increase HK activity and glucose metabolism in murine mesangial (SV40 MES 13) cells. ERK1/2 activation was also evaluated in parallel. Thrombin inhibition (hirudins), PKC depletion, Ser-Thr kinase inhibition (H-7), MEK1/2 inhibition (PD98059), pertussis toxin (PTX), and general inhibitors of transcription or translation were then tested for the ability to attenuate these effects.ResultsThrombin (≥0.01 U/mL) mimicked the effect of phorbol esters, increasing HK activity 50% within 12 to 24 hours (P < 0.05). This effect was inhibited by hirudins, mimicked by thrombin receptor agonists, and accompanied by increased Glc utilization. H-7, PD98059, and general inhibitors of transcription or translation—but not PTX—prevented thrombin-induced HK activity at 24 hours. PKC depletion and PD98059 also blocked the associated phosphorylation and activation of ERK1/2.ConclusionsThrombin increases mesangial cell HK activity via a PTX-insensitive mechanism involving thrombin receptor activation, PKC-dependent activation of ERK1/2, and both ongoing gene transcription and de novo protein synthesis. As such, thrombin is a novel regulator of HK activity in mesangial cells and may play a role in coupling renal injury to metabolism