15,036 research outputs found
Time and Geometric Quantization
In this paper we briefly review the functional version of the Koopman-von
Neumann operatorial approach to classical mechanics. We then show that its
quantization can be achieved by freezing to zero two Grassmannian partners of
time. This method of quantization presents many similarities with the one known
as Geometric Quantization.Comment: Talk given by EG at "Spacetime and Fundamental Interactions: Quantum
Aspects. A conference to honour A.P.Balachandran's 65th birthday
Fungsi Koordinasi Penyidik Polisi Dengan Penyidik Pegawai Negeri Sipil Kehutanan Dalam Proses Penyidikan Tindak Pidana Pembalakan Liar
Tulisan ini membahas tentang fungsi koordinasi Penyidik polisi dalam melaksanakan proses tindak pidana pembalakan liar bersama dengan penyidik pegawai negeri sipil kehutanan yang dalam Implementasinya penyidikan yang dilakukan Penyidik Pegawai Negeri Sipil (PPNS) Kehutanan terkait tindak pidana pembalakan liar dan koordinasi yang terjalin antara Penyidik Pegawai Negeri Sipil (PPNS) Kehutanan dengan Penyidik Kepolisian Republik Indonesia. Jenis penelitian adalah hukum empiris dengan metode pendekatan yuridis sosiologis. Dari hasil penelitian dapat diketahui bahwa penyidikan yang dilakukan oleh PPNS Kehutanan terkait tindak pidana kehutanan terhadap pembalakan liar masih belum optimal, dalam pelaksanaannya PPNS tidak melakukan penahanan terhadap tersangka dengan alasan tersangka bukan berasal dari sindikat yang besar dan tersangka kooperatif dalam memberikan keterangan
Hidden symmetries in a gauge covariant approach, Hamiltonian reduction and oxidation
Hidden symmetries in a covariant Hamiltonian formulation are investigated
involving gauge covariant equations of motion. The special role of the
Stackel-Killing tensors is pointed out. A reduction procedure is used to reduce
the original phase space to another one in which the symmetries are divided
out. The reverse of the reduction procedure is done by stages performing the
unfolding of the gauge transformation followed by the Eisenhart lift in
connection with scalar potentials.Comment: 15 pages; based on a talk at QTS-7 Conference, Prague, August 7-13,
201
Trigonometric Sutherland systems and their Ruijsenaars duals from symplectic reduction
Besides its usual interpretation as a system of indistinguishable
particles moving on the circle, the trigonometric Sutherland system can be
viewed alternatively as a system of distinguishable particles on the circle or
on the line, and these 3 physically distinct systems are in duality with
corresponding variants of the rational Ruijsenaars-Schneider system. We explain
that the 3 duality relations, first obtained by Ruijsenaars in 1995, arise
naturally from the Kazhdan-Kostant-Sternberg symplectic reductions of the
cotangent bundles of the group U(n) and its covering groups
and , respectively. This geometric interpretation
enhances our understanding of the duality relations and simplifies Ruijsenaars'
original direct arguments that led to their discovery.Comment: 34 pages, minor additions and corrections of typos in v
Distance Metric Learning using Graph Convolutional Networks: Application to Functional Brain Networks
Evaluating similarity between graphs is of major importance in several
computer vision and pattern recognition problems, where graph representations
are often used to model objects or interactions between elements. The choice of
a distance or similarity metric is, however, not trivial and can be highly
dependent on the application at hand. In this work, we propose a novel metric
learning method to evaluate distance between graphs that leverages the power of
convolutional neural networks, while exploiting concepts from spectral graph
theory to allow these operations on irregular graphs. We demonstrate the
potential of our method in the field of connectomics, where neuronal pathways
or functional connections between brain regions are commonly modelled as
graphs. In this problem, the definition of an appropriate graph similarity
function is critical to unveil patterns of disruptions associated with certain
brain disorders. Experimental results on the ABIDE dataset show that our method
can learn a graph similarity metric tailored for a clinical application,
improving the performance of a simple k-nn classifier by 11.9% compared to a
traditional distance metric.Comment: International Conference on Medical Image Computing and
Computer-Assisted Interventions (MICCAI) 201
The Star Formation History of the Hubble Sequence: Spatially Resolved Colour Distributions of Intermediate Redshift Galaxies in the Hubble Deep Field
We analyse the spatially resolved colours of distant galaxies of known
redshift in the Hubble Deep Field, using a new technique based on matching
resolved four-band internal colour data to the predictions of evolutionary
synthesis models. We quantify the relative age, dispersion in age, ongoing
star-formation rate, star-formation history, and dust content of these
galaxies. To demonstrate the potential of the method, we study the
near-complete sample of 32 I ~ 0.5 studied by
Bouwens et al (1997). The dispersion of the internal colours of a sample of
0.4<z<1 early-type field galaxies in the HDF indicates that ~40% [4/11] show
evidence of star formation which must have occurred within the past third of
their ages at the epoch of observation. For a sample of well-defined spirals,
we similarly exploit the dispersion in colour to analyse the relative histories
of bulge and disc stars, in order to resolve the current controversy regarding
the ages of galactic bulges. Dust and metallicity gradients are ruled out as
major contributors to the colour dispersions we observe in these systems. The
median ages of bulge stars are found to be signicantly older than those in
galactic discs, and exhibit markedly different star-formation histories. This
result is inconsistent with a secular growth of bulges from disc instabilities,
but consistent with gradual disc formation by accretion of gas onto bulges, as
predicted by hierarchical theories. We extend our technique in order to discuss
the star formation history of the entire Bouwens et al sample in the context of
earlier studies concerned with global star formation histories.Comment: 8 colour postscript figures plus LaTeX source; submitted to MNRAS.
Uses the mnras.sty LaTeX style fil
Priority-grouping method for parallel multi-scheduling in Grid
With the advent in multicore computers, the scheduling of Grid jobs can be made more effective if scaled to fully utilize the underlying hardware, and parallelized to benefit from the exploitation of multicores. The fact that sequential algorithms do not scale with multicore systems nor benefit from parallelism remains a major obstacle to scheduling in the Grid. As multicore systems become ever more pervasive in our computing lives, over reliance on such systems for passive parallelism does not offer the best option in harnessing the benefits of their multiprocessors for Grid scheduling. An explicit means of exploiting parallelism for Grid scheduling is required. The Group-based Parallel Multi-scheduler, introduced in this paper, is aimed at effectively exploiting the benefits of multicore systems for Grid scheduling by splitting jobs and machines into paired groups and independently scheduling jobs in parallel from those groups. We implemented two job grouping methods, Execution Time Balanced (ETB) and Execution Time Sorted then Balanced (ETSB), and two machine grouping methods, Evenly Distributed (EvenDist) and Similar Together (SimTog). For each method, we varied the number of groups between 2, 4 and 8. We then executed the MinMin Grid scheduling algorithm independently within the groups. We demonstrated that by sharing jobs and machines into groups before scheduling, the computation time for the scheduling process drastically improved by magnitudes of 85% over the ordinary MinMin algorithm when implemented on a HPC system. We also found that our balanced group based approach achieved better results than our previous Priority based grouping approach
Soliton form factors from lattice simulations
The form factor provides a convenient way to describe properties of
topological solitons in the full quantum theory, when semiclassical concepts
are not applicable. It is demonstrated that the form factor can be calculated
numerically using lattice Monte Carlo simulations. The approach is very general
and can be applied to essentially any type of soliton. The technique is
illustrated by calculating the kink form factor near the critical point in
1+1-dimensional scalar field theory. As expected from universality arguments,
the result agrees with the exactly calculable scaling form factor of the
two-dimensional Ising model.Comment: 5 pages, 3 figures; v2: discussion extended, references added,
version accepted for publication in PR
Group-based parallel multi-scheduler for grid computing
With the advent in multicore computers, the scheduling of Grid jobs can be made more effective if scaled to fully utilize the underlying hardware, and parallelized to benefit from the exploitation of multicores. The fact that sequential algorithms do not scale with multicore systems nor benefit from parallelism remains a major obstacle to scheduling in the Grid. As multicore systems become ever more pervasive in our computing lives, over reliance on such systems for passive parallelism does not offer the best option in harnessing the benefits of their multiprocessors for Grid scheduling. An explicit means of exploiting parallelism for Grid scheduling is required. The Group-based Parallel Multi-scheduler, introduced in this paper, is aimed at effectively exploiting the benefits of multicore systems for Grid scheduling by splitting jobs and machines into paired groups and independently scheduling jobs in parallel from those groups. We implemented two job grouping methods, Execution Time Balanced (ETB) and Execution Time Sorted then Balanced (ETSB), and two machine grouping methods, Evenly Distributed (EvenDist) and Similar Together (SimTog). For each method, we varied the number of groups between 2, 4 and 8. We then executed the MinMin Grid scheduling algorithm independently within the groups. We demonstrated that by sharing jobs and machines into groups before scheduling, the computation time for the scheduling process drastically improved by magnitudes of 85% over the ordinary MinMin algorithm when implemented on a HPC system. We also found that our balanced group based approach achieved better results than our previous Priority based grouping approach
The Moduli Space of BPS Domain Walls
N=2 SQED with several flavors admits multiple, static BPS domain wall
solutions. We determine the explicit two-kink metric and examine the dynamics
of colliding domain walls. The multi-kink metric has a toric Kahler structure
and we reduce the Kahler potential to quadrature. In the second part of this
paper, we consider semi-local vortices compactified on circle. We argue that,
in the presence of a suitable Wilson line, the vortices separate into domain
wall constituents. These play the role of fractional instantons in
two-dimensional gauge theories and sigma-models.Comment: 16 pages, LaTex, 2 figures; factors of zeta corrected, meaning of
cross-terms elucidated, further clarifying comments; (more) references adde
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