41,906 research outputs found
Performance Evaluation of Sparse Matrix Multiplication Kernels on Intel Xeon Phi
Intel Xeon Phi is a recently released high-performance coprocessor which
features 61 cores each supporting 4 hardware threads with 512-bit wide SIMD
registers achieving a peak theoretical performance of 1Tflop/s in double
precision. Many scientific applications involve operations on large sparse
matrices such as linear solvers, eigensolver, and graph mining algorithms. The
core of most of these applications involves the multiplication of a large,
sparse matrix with a dense vector (SpMV). In this paper, we investigate the
performance of the Xeon Phi coprocessor for SpMV. We first provide a
comprehensive introduction to this new architecture and analyze its peak
performance with a number of micro benchmarks. Although the design of a Xeon
Phi core is not much different than those of the cores in modern processors,
its large number of cores and hyperthreading capability allow many application
to saturate the available memory bandwidth, which is not the case for many
cutting-edge processors. Yet, our performance studies show that it is the
memory latency not the bandwidth which creates a bottleneck for SpMV on this
architecture. Finally, our experiments show that Xeon Phi's sparse kernel
performance is very promising and even better than that of cutting-edge general
purpose processors and GPUs
On the Solution of Linear Programming Problems in the Age of Big Data
The Big Data phenomenon has spawned large-scale linear programming problems.
In many cases, these problems are non-stationary. In this paper, we describe a
new scalable algorithm called NSLP for solving high-dimensional, non-stationary
linear programming problems on modern cluster computing systems. The algorithm
consists of two phases: Quest and Targeting. The Quest phase calculates a
solution of the system of inequalities defining the constraint system of the
linear programming problem under the condition of dynamic changes in input
data. To this end, the apparatus of Fejer mappings is used. The Targeting phase
forms a special system of points having the shape of an n-dimensional
axisymmetric cross. The cross moves in the n-dimensional space in such a way
that the solution of the linear programming problem is located all the time in
an "-vicinity of the central point of the cross.Comment: Parallel Computational Technologies - 11th International Conference,
PCT 2017, Kazan, Russia, April 3-7, 2017, Proceedings (to be published in
Communications in Computer and Information Science, vol. 753
Higgs bosons of a supersymmetric model at the Large Hadron Collider
It is found that CP symmetry may be explicitly broken in the Higgs sector of
a supersymmetric model with two extra neutral gauge bosons at the
one-loop level. The phenomenology of the model, the Higgs sector in particular,
is studied for a reasonable parameter space of the model, in the presence of
explicit CP violation at the one-loop level. At least one of the neutral Higgs
bosons of the model might be produced via the fusion process at the Large
Hadron Collider.Comment: 23 pages, 5 figures, JHE
New approximations for the cone of copositive matrices and its dual
We provide convergent hierarchies for the cone C of copositive matrices and
its dual, the cone of completely positive matrices. In both cases the
corresponding hierarchy consists of nested spectrahedra and provide outer
(resp. inner) approximations for C (resp. for its dual), thus complementing
previous inner (resp. outer) approximations for C (for the dual). In
particular, both inner and outer approximations have a very simple
interpretation. Finally, extension to K-copositivity and K-complete positivity
for a closed convex cone K, is straightforward.Comment: 8
Exosomes and Exosomal miRNA in Respiratory Diseases
Exosomes are nanosized vesicles released from every cell in the body including those in the respiratory tract and lungs. They are found in most body fluids and contain a number of different biomolecules including proteins, lipids, and both mRNA and noncoding RNAs. Since they can release their contents, particularly miRNAs, to both neighboring and distal cells, they are considered important in cell-cell communication. Recent evidence has shown their possible importance in the pathogenesis of several pulmonary diseases. The differential expression of exosomes and of exosomal miRNAs in disease has driven their promise as biomarkers of disease enabling noninvasive clinical diagnosis in addition to their use as therapeutic tools. In this review, we summarize recent advances in this area as applicable to pulmonary diseases
Photonic crystal thin films of GaAs prepared by atomic layer deposition
Photonic crystal thin films were fabricated via the self-assembly of a lattice of silica spheres on silicon (100) substrates. Progressive infilling of the air spaces within the structure with GaAs was achieved using trimethylgallium and arsine under atomic-layer-deposition conditions. Samples with the highest levels of GaAs infill were subsequently inverted using selective etching. Reflectance spectra are interpreted via the Bragg expression and calculated photonic band structure diagrams. For GaAs infilled and inverted samples, the relative positions of the first and second order Bragg reflections are strongly influenced by the wavelength dependent refractive index
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