9,022 research outputs found
Anisotropy in the sky distributions of the short and intermediate gamma-ray bursts: Breakdown of the cosmological principle?
After the discovery of the anisotropy in the sky-distribution of intermediate
gamma-ray bursts recently also the distribution of the short gamma-ray bursts
is proven to be anisotropic. The impact of these behaviors on the validity of
the cosmological principle is shortly discussed.Comment: 3 pages, 1 figure, to appear in the proceedings of the Sixth
Huntsville Gamma-Ray Burst Symposium, edited by C.A. Meegan, N. Gehrels, and
C. Kouvelioto
The Impact of Radiotherapy Dose on Local Control of Ewing's Sarcoma of Bone
Purpose. Improvements in the systemic management of Ewing's sarcoma of bone over the last 20 years have led to a
dramatic improvement in survival. The corollary is that treatment of the primary disease requires re-evaluation, since a
significant number of patients still suffer local relapse
A Preliminary Report on Unique Hail and Tornadic Storm Observations in Central Illinois and Eastern Indiana on 3 April 1974
published or submitted for publicationis peer reviewedOpe
Recommended from our members
Detection of coherent airstreams using cluster analysis: application to an extratropical cyclone
Flow in geophysical fluids is commonly summarized by coherent streams, for example conveyor belt flows in extratropical cyclones or jet streaks in the upper troposphere. Typically, parcel trajectories are calculated from the flow field and subjective thresholds are used to distinguish coherent streams of interest. This methodology contribution develops a more objective approach to distinguish coherent airstreams within extratropical cyclones. Agglomerative clustering is applied to trajectories along with a method to identify the optimal number of cluster classes. The methodology is applied to trajectories associated with the low-level jets of a well-studied extratropical cyclone. For computational efficiency, a constraint that trajectories must pass through these jet regions is applied prior to clustering; the partitioning into different airstreams is then performed by the agglomerative clustering. It is demonstrated that the methodology can identify the salient flow structures of cyclones: the warm and cold conveyor belts. A test focusing on the airstreams terminating at the tip of the bent-back front further demonstrates the success of the method in that it can distinguish fine-scale flow structure such as descending sting jet airstreams
Flavor-Changing Processes in Extended Technicolor
We analyze constraints on a class of extended technicolor (ETC) models from
neutral flavor-changing processes induced by (dimension-six) four-fermion
operators. The ETC gauge group is taken to commute with the standard-model
gauge group. The models in the class are distinguished by how the left- and
right-handed components of the quarks and charged leptons transform
under the ETC group. We consider and other pseudoscalar
meson mixings, and conclude that they are adequately suppressed if the and
components of the relevant quarks are assigned to the same (fundamental or
conjugate-fundamental) representation of the ETC group. Models in which the
and components of the down-type quarks are assigned to relatively conjugate
representations, while they can lead to realistic CKM mixing and intra-family
mass splittings, do not adequately suppress these mixing processes. We identify
an approximate global symmetry that elucidates these behavioral differences and
can be used to analyze other possible representation assignments.
Flavor-changing decays, involving quarks and/or leptons, are adequately
suppressed for any ETC-representation assignment of the and components
of the quarks, as well as the leptons. We draw lessons for future ETC model
building.Comment: 25 page
Orthogonality catastrophe in a composite fermion liquid
We discuss the emergence of an orthogonality catastrophe in the response of a
composite fermion liquid as the filling factor \nu approaches 1/2m, where
m=1,2,3.... A tunneling experiment is proposed in which dramatic changes in the
I-V characteristic should be observable as \nu is varied. Explicit I-V
characteristics calculated within the so-called Modified Random Phase
Approximation, are provided for \nu=1/3 -> \nu=1/2.Comment: Latex two-column 6 pages including 5 figure
Microarray Analysis of Bacterial Gene Expression: Towards the Regulome
Microarray technology allows co-regulated genes to be identified. In order to identify genes that are controlled by specific regulators, gene expression can be compared
in mutant and wild-type bacteria. However, there are a number of pitfalls with this
approach; in particular, the regulator may not be active under the conditions in which
the wild-type strain is cultured. Once co-regulated genes have been identified, proteinbinding
motifs can be identified. By combining these data with a map of promoters,
or operons (the operome), the regulatory networks in the cell (the regulome) can start
to be built up
Localized magnetoplasmon modes arising from broken translational symmetry in semiconductor superlattices
The electromagnetic propagator associated with the localized collective
magnetoplasmon excitations in a semiconductor superlattice with broken
translational symmetry, is calculated analytically within linear response
theory. We discuss the properties of these collective excitations in both
radiative and non-radiative regimes of the electromagnetic spectra. We find
that low frequency retarded modes arise when the surface density of carriers at
the symmetry breaking layer is lower than the density at the remaining layers.
Otherwise a doublet of localized, high-frequency magnetoplasmon-like modes
occurs.Comment: Revtex file + separate pdf figure
On the rigidity of a hard sphere glass near random close packing
We study theoretically and numerically the microscopic cause of the
mechanical stability of hard sphere glasses near their maximum packing. We show
that, after coarse-graining over time, the hard sphere interaction can be
described by an effective potential which is exactly logarithmic at the random
close packing . This allows to define normal modes, and to apply recent
results valid for elastic networks: mechanical stability is a non-local
property of the packing geometry, and is characterized by some length scale
which diverges at [1, 2]. We compute the scaling of the bulk and
shear moduli near , and speculate on the possible implications of these
results for the glass transition.Comment: 7 pages, 4 figures. Figure 4 had a wrong unit in abscissa, which was
correcte
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