780 research outputs found
Addendum to: Search for anomalous top-gluon couplings at LHC revisited
In our latest paper "Search for anomalous top-gluon couplings at LHC
revisited" in Eur. Phys. J. C65 (2010), 127-135 (arXiv:0910.3049 [hep-ph]), we
studied possible effects of nonstandard top-gluon couplings through the
chromoelectric and chromomagnetic moments of the top quark using the total
cross section of ppbar/pp --> ttbar X at Tevatron/LHC. There we pointed out
that LHC data could give a stronger constraint on those two parameters, which
would be hard to obtain from Tevatron data alone. We show here the first CMS
measurement of this cross section actually makes it possible.Comment: 5 pages, 1 figure, LaTeX2e, Final version (to appear in Eur. Phys. C
Engrailed, a homeodomain protein, can repress in vitro transcription by competition with the TATA box-binding protein transcription factor IID.
High-pressure effects on isotropic superconductivity in the iron-free layered pnictide superconductor BaPd2As2
While the layered 122 iron arsenide superconductors are highly anisotropic,
unconventional, and exhibit several forms of electronic orders that coexist or
compete with superconductivity in different regions of their phase diagrams, we
find in the absence of iron in the structure that the superconducting
characteristics of the end member BaPd2As2 are surprisingly conventional. Here
we report on complementary measurements of specific heat, magnetic
susceptibility, resistivity measurements, Andreev spectroscopy, and synchrotron
high pressure x-ray diffraction measurements supplemented with theoretical
calculations for BaPd2As2. Its superconducting properties are completely
isotropic as demonstrated by the critical fields, which do not depend on the
direction of the applied field. Under the application of high pressure, Tc is
linearly suppressed, which is the typical behavior of classical phonon-mediated
superconductors with some additional effect of a pressure-induced decrease in
the electronic density of states and the electron-phonon coupling parameters.
Structural changes in the layered BaPd2As2 have been studied by means of
angle-dispersive diffraction in a diamond-anvil cell. At 12 GPa and 24.2 GPa we
observed pressure induced lattice distortions manifesting as the discontinuity
and, hence discontinuity in the Birch-Murnaghan equation of state. The bulk
modulus is B0=40(6) GPa below 12 GPa and B0=142(3) GPa below 27.2 GPa
Non-equilibrium fluctuation theorems in the presence of local heating
We study two non-equilibrium work fluctuation theorems, the Crooks' theorem
and the Jarzynski equality, for a test system coupled to a spatially extended
heat reservoir whose degrees of freedom are explicitly modeled. The sufficient
conditions for the validity of the theorems are discussed in detail and
compared to the case of classical Hamiltonian dynamics. When the conditions are
met the fluctuation theorems are shown to hold despite the fact that the
immediate vicinity of the test system goes out of equilibrium during an
irreversible process. We also study the effect of the coupling to the heat
reservoir on the convergence of to its theoretical mean
value, where is the work done on the test system and is the inverse
temperature. It is shown that the larger the local heating, the slower the
convergence.Comment: 8 pages, 7 figures, revised and extended version, to appear in Phys.
Rev.
Slow group velocity and Cherenkov radiation
We theoretically study the effect of ultraslow group velocities on the
emission of Vavilov-Cherenkov radiation in a coherently driven medium. We show
that in this case the aperture of the group cone on which the intensity of the
radiation peaks is much smaller than that of the usual wave cone associated
with the Cherenkov coherence condition. We show that such a singular behaviour
may be observed in a coherently driven ultracold atomic gas.Comment: 4 pages, 4 figure
Current fluctuations in stochastic systems with long-range memory
We propose a method to calculate the large deviations of current fluctuations
in a class of stochastic particle systems with history-dependent rates.
Long-range temporal correlations are seen to alter the speed of the large
deviation function in analogy with long-range spatial correlations in
equilibrium systems. We give some illuminating examples and discuss the
applicability of the Gallavotti-Cohen fluctuation theorem.Comment: 10 pages, 1 figure. v2: Minor alterations. v3: Very minor alterations
for consistency with published version appearing at
http://stacks.iop.org/1751-8121/42/34200
KLEIN: A New Family of Lightweight Block Ciphers
Resource-efficient cryptographic primitives become fundamental for realizing both security and efficiency in embedded systems like RFID tags and sensor nodes. Among those primitives, lightweight block cipher plays a major role as a building block for security protocols. In this paper, we describe a new family of lightweight block ciphers named KLEIN, which is designed for resource-constrained devices such as wireless sensors and RFID tags. Compared to the related proposals, KLEIN has advantage in the software performance on legacy sensor platforms, while in the same time its hardware implementation can also be compact
Molecular Phylogeny and Evolution of Parabasalia with Improved Taxon Sampling and New Protein Markers of Actin and Elongation Factor-1α
BACKGROUND: Inferring the evolutionary history of phylogenetically isolated, deep-branching groups of taxa-in particular determining the root-is often extraordinarily difficult because their close relatives are unavailable as suitable outgroups. One of these taxonomic groups is the phylum Parabasalia, which comprises morphologically diverse species of flagellated protists of ecological, medical, and evolutionary significance. Indeed, previous molecular phylogenetic analyses of members of this phylum have yielded conflicting and possibly erroneous inferences. Furthermore, many species of Parabasalia are symbionts in the gut of termites and cockroaches or parasites and therefore formidably difficult to cultivate, rendering available data insufficient. Increasing the numbers of examined taxa and informative characters (e.g., genes) is likely to produce more reliable inferences. PRINCIPAL FINDINGS: Actin and elongation factor-1α genes were identified newly from 22 species of termite-gut symbionts through careful manipulations and seven cultured species, which covered major lineages of Parabasalia. Their protein sequences were concatenated and analyzed with sequences of previously and newly identified glyceraldehyde-3-phosphate dehydrogenase and the small-subunit rRNA gene. This concatenated dataset provided more robust phylogenetic relationships among major groups of Parabasalia and a more plausible new root position than those previously reported. CONCLUSIONS/SIGNIFICANCE: We conclude that increasing the number of sampled taxa as well as the addition of new sequences greatly improves the accuracy and robustness of the phylogenetic inference. A morphologically simple cell is likely the ancient form in Parabasalia as opposed to a cell with elaborate flagellar and cytoskeletal structures, which was defined as most basal in previous inferences. Nevertheless, the evolution of Parabasalia is complex owing to several independent multiplication and simplification events in these structures. Therefore, systematics based solely on morphology does not reflect the evolutionary history of parabasalids
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