11,468 research outputs found
Spectra, composition, and interactions of nuclei above 10 TeV using magnet-interferometric chambers
Although the SCIN-MAGIC experiment has, like all ASTROMAG and most other Attached Payload experiments, been 'deselected' from Space Station, it is expected that ultimately such emulsion chambers will be flown on the Station. Some brief studies are described which were made in support of the design efforts for such a program being conducted at NASA Marshall
Parallel Computing on a PC Cluster
The tremendous advance in computer technology in the past decade has made it
possible to achieve the performance of a supercomputer on a very small budget.
We have built a multi-CPU cluster of Pentium PC capable of parallel
computations using the Message Passing Interface (MPI). We will discuss the
configuration, performance, and application of the cluster to our work in
physics.Comment: 3 pages, uses Latex and aipproc.cl
CAutoCSD-evolutionary search and optimisation enabled computer automated control system design
This paper attempts to set a unified scene for various linear time-invariant (LTI) control system design schemes, by transforming the existing concept of 'Computer-Aided Control System Design' (CACSD) to the novel 'Computer-Automated Control System Design' (CAutoCSD). The first step towards this goal is to accommodate, under practical constraints, various design objectives that are desirable in both time and frequency-domains. Such performance-prioritised unification is aimed to relieve practising engineers from having to select a particular control scheme and from sacrificing certain performance goals resulting from pre-committing to the adopted scheme. With the recent progress in evolutionary computing based extra-numeric, multi-criterion search and optimisation techniques, such unification of LTI control schemes becomes feasible, analytically and practically, and the resultant designs can be creative. The techniques developed are applied to, and illustrated by, three design problems. The unified approach automatically provides an integrator for zero-steady state error in velocity control of a DC motor, meets multiple objectives in designing an LTI controller for a non-minimum phase plant and offers a high-performing LTI controller network for a nonlinear chemical process
Genome-wide profiling of uncapped mRNA
Gene transcripts are under extensive posttranscriptional regulation, including the regulation of their
stability. A major route for mRNA degradation produces uncapped mRNAs, which can be generated by
decapping enzymes, endonucleases, and small RNAs. Profiling uncapped mRNA molecules is important for
the understanding of the transcriptome, whose composition is determined by a balance between mRNA
synthesis and degradation. In this chapter, we describe a method to profile these uncapped mRNAs at the
genome scale
Flux quantization and superfluid weight in doped antiferromagnets
Doped antiferromagnets, described by a t-t'-J model and a suitable 1/N
expansion, exhibit a metallic phase-modulated antiferromagnetic ground state
close to half-filling. Here we demonstrate that the energy of latter state is
an even periodic function of the external magnetic flux threading the square
lattice in an Aharonov-Bohm geometry. The period is equal to the flux quantum
entering the Peierls phase factor of the hopping
matrix elements. Thus flux quantization and a concomitant finite value of
superfluid weight D_s occur along with metallic antiferromagnetism. We argue
that in the context of the present effective model, whereby carriers are
treated as hard-core bosons, the charge q in the associated flux quantum might
be set equal to 2e. Finally, the superconducting transition temperature T_c is
related to D_s linearly, in accordance to the generic Kosterlitz-Thouless type
of transition in a two-dimensional system, signaling the coherence of the phase
fluctuations of the condensate. The calculated dependence of T_c on hole
concentration is qualitatively similar to that observed in the high-temperature
superconducting cuprates.Comment: 5 pages, 2 figures, to be published in J. Phys. Condens. Matte
Black hole solutions in the warped DGP braneworld
We study the static, analytical solution of black holes in the warped DGP
braneworld scenario. We show that the linearized field equations and matching
conditions lead to solutions that are not compatible with
Schwarzschild-(A)dS solutions on the brane. This incompatibility is
similar to vDVZ discontinuity in massive gravity theory. Following the standard
procedure to remove this discontinuity, which firstly was proposed by
Vainshtein, we keep some appropriate nonlinear terms in the field equations.
This strategy has its origin in the fact that the spatial extrinsic curvature
of the brane plays a crucial role in the nonlinear nature of the solutions and
also in recovering the well-measured predictions of General Relativity (GR) at
small scales. Using this feature, we obtained an interesting black string
solution in the bulk when it is compatible with 4D GR solutions on the brane.Comment: 15 pages, no figure
Diffusive scaling and the high-energy limit of deep inelastic scattering in QCD at large
URL: http://www-spht.cea.fr/articles/T06/001 Processus diffractifs en QCD à haute énergie et grand nombre de couleurs http://fr.arxiv.org/abs/hep-ph/0601150International audienceWithin the limits of the large-- approximation (with the number of colors), we establish the high--energy behaviour of the diffractive and inclusive cross--sections for deep inelastic scattering at fixed impact parameter. We demonstrate that for sufficiently high energies and up to very large values of , well above the proton average saturation momentum , the cross--sections are dominated by dense fluctuations in the target wavefunction, that is, by the relatively rare gluon configurations which are at saturation on the resolution scale of the virtual photon. This has important physical consequences, like the emergence of a new, {\em diffusive}, scaling, which replaces the `geometric scaling' property characteristic of the mean field approximation. To establish this, we shall rely on a dipole version of the Good--Walker formula for diffraction (that we shall derive here in the context of DIS), together with the high--energy estimates for the dipole scattering amplitudes which follow from the recently established evolution equations with Pomeron loops and include the relevant fluctuations. We also find that, as a consequence of fluctuations, the diffractive cross--section at high energy is dominated by the elastic scattering of the quark--antiquark component of the virtual photon, up to relatively large virtualities
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