122 research outputs found
HyperLoom possibilities for executing scientific workflows on the cloud
We have developed HyperLoom - a platform for defining and executing scientific workflows in large-scale HPC systems. The computational tasks in such workflows often have non-trivial dependency patterns, unknown execution time and unknown sizes of generated outputs. HyperLoom enables to efficiently execute the workflows respecting task requirements and cluster resources agnostically to the shape or size of the workflow. Although HPC infrastructures provide an unbeatable performance, they may be unavailable or too expensive especially for small to medium workloads. Moreover, for some workloads, due to HPCs not very flexible resource allocation policy, the system energy efficiency may not be optimal at some stages of the execution. In contrast, current public cloud providers such as Amazon, Google or Exoscale allow users a comfortable and elastic way of deploying, scaling and disposing a virtualized cluster of almost any size. In this paper, we describe HyperLoom virtualization and evaluate its performance in a virtualized environment using workflows of various shapes and sizes. Finally, we discuss the Hyperloom potential for its expansion to cloud environments.61140639
Light-Front Aspects of Chiral Symmetry
Spontaneous chiral symmetry breaking and axial anomaly are studied in the
light-front formulation. The existence of multiple vacua and a Nambu-Goldstone
boson, both related to dynamical fermion zero modes, are demonstrated within a
simple sigma model with fermions. The Weyl gauge formulation and a consistent
gauge invariant point-splitting regularization, which includes the light front
time, are crucial for obtaining the anomaly in the massive Schwinger model and
QED(3+1).Comment: 5 pages, Latex2e, uses elsart.cls, to apper in the proceedings of the
X. International Light-Cone Meeting, Heidelberg, June 200
Theta-Vacuum of the Bosonized Massive Light-Front Schwinger Model
The massive Schwinger model in bosonic representation is quantized on the
light front using the Dirac--Bergmann method. The non-perturbative theta-
vacuum in terms of coherent states of the gauge-field zero mode is derived and
found to coincide with the massless case. On the other hand, the mass term
becomes highly non-linear due to the constrained zero mode of the scalar field.
A non-trivial mixing between the normal-mode and zero-mode sectors of the model
is crucial for the correct calculation of the theta-dependence of the leading
order mass correction to the chiral condensate.Comment: 9 pages, LaTe
Essence of the vacuum quark condensate
We show that the chiral-limit vacuum quark condensate is qualitatively
equivalent to the pseudoscalar meson leptonic decay constant in the sense that
they are both obtained as the chiral-limit value of well-defined
gauge-invariant hadron-to-vacuum transition amplitudes that possess a spectral
representation in terms of the current-quark mass. Thus, whereas it might
sometimes be convenient to imagine otherwise, neither is essentially a constant
mass-scale that fills all spacetime. This means, in particular, that the quark
condensate can be understood as a property of hadrons themselves, which is
expressed, for example, in their Bethe-Salpeter or light-front wavefunctions.Comment: 5 pages, 1 figur
Higgs mechanism in a light front formulation
We give a simple derivation of the Higgs mechanism in an abelian light front
field theory. It is based on a finite volume quantization with antiperiodic
scalar fields and a periodic gauge field. An infinite set of degenerate vacua
in the form of coherent states of the scalar field that minimize the light
front energy, is constructed. The corresponding effective Hamiltonian descibes
a massive vector field whose third component is generated by the would-be
Goldstone boson. This mechanism, understood here quantum mechanically in the
form analogous to the space-like quantization, is derived without gauge fixing
as well as in the unitary and the light cone gauge.Comment: 9 page
Application of Thai boxing techniques in MMA
Katedra tělesné výchovyFaculty of EducationPedagogická fakult
Optimization of rules selection for robot soccer strategies
Mobile embedded systems belong among the
typical applications of distributed systems control in realtime.
An example of a mobile control system is a robotic
system. The proposal and realization of such a distributed
control system represents a demanding and complex task
for real-time control. In the process of robot soccer game
applications, extensive data is accumulated. The reduction
of such data is a possible win in a game strategy. The main
topic of this article is a description of an efficient method
for rule selection from a strategy. The proposed algorithm
is based on the geometric representation of rules. A
described problem and a proposed solution can be applied
to other areas dealing with effective searching of rules in
structures that also represent coordinates of the real world.
Because this construed strategy describes a real space and
the stores physical coordinates of real objects, our method
can be used in strategic planning in the real world where
we know the geographical positions of objects.Web of Science11art. no. 1
HyperLoom: A platform for defining and executing scientific pipelines in distributed environments
Real-world scientific applications often encompass end-to-end data processing pipelines composed of a large number of interconnected computational tasks of various granularity. We introduce HyperLoom, an open source platform for defining and executing such pipelines in distributed environments and providing a Python interface for defining tasks. HyperLoom is a self-contained system that does not use an external scheduler for the actual execution of the task. We have successfully employed HyperLoom for executing chemogenomics pipelines used in pharmaceutic industry for novel drug discovery.6
Kinks in Discrete Light Cone Quantization
We investigate non-trivial topological structures in Discrete Light Cone
Quantization (DLCQ) through the example of the broken symmetry phase of the two
dimensional theory using anti periodic boundary condition (APBC). We
present evidence for degenerate ground states which is both a signature of
spontaneous symmetry breaking and mandatory for the existence of kinks. Guided
by a constrained variational calculation with a coherent state ansatz, we then
extract the vacuum energy and kink mass and compare with classical and semi -
classical results. We compare the DLCQ results for the number density of bosons
in the kink state and the Fourier transform of the form factor of the kink with
corresponding observables in the coherent variational kink state.Comment: 10 pages, 3 figure
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