977 research outputs found
Testing improved staggered fermions with and
We study the improvement of staggered fermions using hypercubically smeared
(HYP) links. We calculate the strange quark mass and the kaon B-parameter,
, in quenched QCD on a lattice at . We find
MeV and , where the first error is from
statistics and fitting, and the second from using one-loop matching factors.
The scale (GeV) is set by , and is determined using the
kaon mass. Comparing to quenched results obtained using unimproved staggered
fermions and other discretizations, we argue that the size of discretization
errors in is substantially reduced by improvement.Comment: 9 pages, 12 figure, referee's comments are incorporate
Massive gas gangrene secondary to occult colon carcinoma
AbstractGas gangrene is a rare but often fatal soft-tissue infection. Because it is uncommon and the classic symptom of crepitus does not appear until the infection is advanced, prompt diagnosis requires a high index of suspicion. We present a case report of a middle-aged man who presented with acute onset lower-extremity pain that was initially thought to be due to deep vein thrombosis. After undergoing workup for pulmonary embolism, he was found to have massive gas gangrene of the lower extremity secondary to an occult colon adenocarcinoma and died within hours of presentation from multisystem organ failure
Hadron Spectrum with Wilson fermions
We present results of a high statistics study of the quenched spectrum using
Wilson fermions at on lattices. We calculate the
masses of mesons and baryons composed of both degenerate and non-degenerate
quarks. Using non-degenerate quark combinations allows us to study baryon mass
splittings in detail. We find significant deviations from the lowest order
chiral expansion, deviations that are consistent with the expectations of
quenched chiral perturbation theory. We find that there is a
systematic error in the extracted value of , depending on the meson mass
ratio used to set its value. Using the largest estimate of we find that
the extrapolated octet mass-splittings are in agreement with the experimental
values, as is , while the decuplet splittings are 30% smaller
than experiment. Combining our results with data from the GF11 collaboration we
find considerable ambiguity in the extrapolation to the continuum limit. Our
preferred values are and , suggesting that the quenched approximation is good to only . We also analyze the discretization errors in heavy quark
masses.Comment: 52 pages. Tex. Modified "axis" source for figures also included.
Needs macro packages lanlmac and epsf. Uses hyperbasics if available.
Significant number of typographical errors correcte
Hybrid Approach for Resource Allocation in Cloud Infrastructure Using Random Forest and Genetic Algorithm
In cloud computing, the virtualization technique is a significant technology to optimize the power consumption of the cloud data center. In this generation, most of the services are moving to the cloud resulting in increased load on data centers. As a result, the size of the data center grows and hence there is more energy consumption. To resolve this issue, an efficient optimization algorithm is required for resource allocation. In this work, a hybrid approach for virtual machine allocation based on genetic algorithm (GA) and the random forest (RF) is proposed which belongs to a class of supervised machine learning techniques. The aim of the work is to minimize power consumption while maintaining better load balance among available resources and maximizing resource utilization. The proposed model used a genetic algorithm to generate a training dataset for the random forest model and further get a trained model. The real-time workload traces from PlanetLab are used to evaluate the approach. The results showed that the proposed GA-RF model improves energy consumption, execution time, and resource utilization of the data center and hosts as compared to the existing models. The work used power consumption, execution time, resource utilization, average start time, and average finish time as performance metrics
Defining the Incremental Utility of Prostate Multiparametric Magnetic Resonance Imaging at Standard and Specialized Read in Predicting Extracapsular Extension of Prostate Cancer
AbstractMultiparametric magnetic resonance imaging (mpMRI) is increasingly used in staging early prostate cancer (PCa) but remains heavily reader-dependent. We aim to define the incremental utility of mpMRI over clinical parameters in determining the pathologic extracapsular extension (pECE) of PCa interpreted in a standard radiologic setting and when further over-read by a specialized reader. We retrospectively reviewed 120 men with clinically localized PCa undergoing mpMRI and radical prostatectomy. We obtained radiologic prediction of pECE from standard radiologic reports (standard read) and by a specialized reader blinded to clinical and pathologic findings (specialized read). We determined the incremental benefit of standard read and specialized read by sequential addition to a baseline clinical parameters-only logistic regression model predicting pECE. The sensitivity and specificity of standard read were 77% and 44%, respectively, whereas those of specialized read were 86% and 81%. The positive likelihood ratio was 1.7 at baseline, 1.7 adding standard read, and 6.5 adding specialized read. The negative likelihood ratio was 0.6 at baseline, 0.5 adding standard read, and 0.1 adding specialized read. Standard read modestly improved prediction of pECE, whereas specialized read improved it moderately.Patient summaryThe incremental benefit of mpMRI over clinical information is small but increases to moderate with a specialized second opinion. This second opinion may be useful when considering active surveillance, nerve-sparing surgery, or focal therapy
Intelligent Fault-Tolerant Mechanism for Data Centers of Cloud Infrastructure
Fault tolerance in cloud computing is considered as one of the most vital issues to deliver reliable services. Checkpoint/restart is one of the methods used to enhance the reliability of the cloud services. However, many existing methods do not focus on virtual machine (VM) failure that occurs due to the higher response time of a node, byzantine fault, and performance fault, and existing methods also ignore the optimization during the recovery phase. This paper proposes a checkpoint/restart mechanism to enhance reliability of cloud services. Our work is threefold: (1) we design an algorithm to identify virtual machine failure due to several faults; (2) an algorithm to optimize the checkpoint interval time is designed; (3) lastly, the asynchronous checkpoint/restart with log-based recovery mechanism is used to restart the failed tasks. The valuation results obtained using a real-time dataset shows that the proposed model reduces power consumption and improves the performance with a better fault tolerance solution compared to the nonoptimization method
Order a improved renormalization constants
We present non-perturbative results for the constants needed for on-shell
improvement of bilinear operators composed of Wilson fermions. We work
at and 6.2 in the quenched approximation. The calculation is done
by imposing axial and vector Ward identities on correlators similar to those
used in standard hadron mass calculations. A crucial feature of the calculation
is the use of non-degenerate quarks. We also obtain results for the constants
needed for off-shell improvement of bilinears, and for the scale and
scheme independent renormalization constants, (Z_A), (Z_V) and (Z_S/Z_P).
Several of the constants are determined using a variety of different Ward
identities, and we compare their relative efficacies. In this way, we find a
method for calculating that gives smaller errors than that used
previously. Wherever possible, we compare our results with those of the ALPHA
collaboration (who use the Schr\"odinger functional) and with 1-loop
tadpole-improved perturbation theory.Comment: 48 pages. Modified "axis" source for figures also included. Typos
corrected (version published in Phys. Rev. D
Light Quark Masses from Lattice QCD
We present estimates of the masses of light quarks using lattice data. Our
main results are based on a global analysis of all the published data for
Wilson, Sheikholeslami-Wohlert (clover), and staggered fermions, both in the
quenched approximation and with dynamical flavors. We find that the
values of masses with the various formulations agree after extrapolation to the
continuum limit for the theory. Our best estimates, in the MSbar scheme
at , are \mbar=3.4 +- 0.4 +- 0.3 MeV and in the quenched approximation. The results, \mbar = 2.7 +- 0.3 +-
0.3 MeV and , are preliminary. (A linear
extrapolation in would further reduce these estimates for the physical
case of three dynamical flavors.) These estimates are smaller than
phenomenological estimates based on sum rules, but maintain the ratios
predicted by chiral perturbation theory. The new results have a significant
impact on the extraction of from the Standard Model. Using
the same lattice data we estimate the quark condensate using the
Gell-Mann-Oakes-Renner relation. Again the three formulations give consistent
results after extrapolation to , and the value turns out to be
correspondingly larger, roughly preserving m_s \vev{\bar \psi \psi}.Comment: 32 pages. Package submitted in uufiles format: unpack and tex
paper.tex. Modified "axis" source for figures also included. Latex2e
document. Uncomment hyperref if available. This is the final published
versio
Fluctuations and Correlations of net baryon number, electric charge, and strangeness: A comparison of lattice QCD results with the hadron resonance gas model
We calculate the quadratic fluctuations of net baryon number, electric charge
and strangeness as well as correlations among these conserved charges in
(2+1)-flavor lattice QCD at zero chemical potential. Results are obtained using
calculations with tree level improved gauge and the highly improved staggered
quark (HISQ) actions with almost physical light and strange quark masses at
three different values of the lattice cut-off. Our choice of parameters
corresponds to a value of 160 MeV for the lightest pseudo scalar Goldstone mass
and a physical value of the kaon mass. The three diagonal charge
susceptibilities and the correlations among conserved charges have been
extrapolated to the continuum limit in the temperature interval 150 MeV <T <
250 MeV. We compare our results with the hadron resonance gas (HRG) model
calculations and find agreement with HRG model results only for temperatures
T<= 150 MeV. We observe significant deviations in the temperature range 160 MeV
< T < 170 MeV and qualitative differences in the behavior of the three
conserved charge sectors. At T < 160 MeV quadratic net baryon number
fluctuations in QCD agree with HRG model calculations while, the net electric
charge fluctuations in QCD are about 10% smaller and net strangeness
fluctuations are about 20% larger. These findings are relevant to the
discussion of freeze-out conditions in relativistic heavy ion collisions.Comment: 17 pages, 18 EPS-files, 5 tables, revised version includes continuum
limit extrapolations of off-diagonal susceptibilities, to appear in Phys.
Rev.
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