1,201 research outputs found
The Stress-Energy Tensor in Soluble Models of Spherically Symmetric Charged Black Hole Evaporation
We study the decay of a near-extremal black hole in AdS, related to the
near-horizon region of 3+1-dimensional Reissner-Nordstr\"om spacetime,
following Fabbri, Navarro, and Navarro-Salas. Back-reaction is included in a
semiclassical approximation. Calculations of the stress-energy tensor of matter
coupled to the physical spacetime for an affine null observer demonstrate that
the black hole evaporation proceeds smoothly and the near-extremal black hole
evolves back to an extremal ground state, until this approximation breaks down.Comment: 19 pages, 14 figure
An overview of the current status of CMB observations
In this paper we briefly review the current status of the Cosmic Microwave
Background (CMB) observations, summarising the latest results obtained from CMB
experiments, both in intensity and polarization, and the constraints imposed on
the cosmological parameters. We also present a summary of current and future
CMB experiments, with a special focus on the quest for the CMB B-mode
polarization.Comment: Latest CMB results have been included. References added. To appear in
"Highlights of Spanish Astrophysics V", Proceedings of the VIII Scientific
Meeting of the Spanish Astronomical Society (SEA) held in Santander, 7-11
July, 200
Discrete molecular dynamics simulations of peptide aggregation
We study the aggregation of peptides using the discrete molecular dynamics
simulations. At temperatures above the alpha-helix melting temperature of a
single peptide, the model peptides aggregate into a multi-layer parallel
beta-sheet structure. This structure has an inter-strand distance of 0.48 nm
and an inter-sheet distance of 1.0 nm, which agree with experimental
observations. In this model, the hydrogen bond interactions give rise to the
inter-strand spacing in beta-sheets, while the Go interactions among side
chains make beta-strands parallel to each other and allow beta-sheets to pack
into layers. The aggregates also contain free edges which may allow for further
aggregation of model peptides to form elongated fibrils.Comment: 15 pages, 8 figure
Critical properties of superconducting Ba1-xKxFe2As2
Magnetisation and magnetoresistance measurements have been carried out on
superconducting Ba1-xKxFe2As2 samples with x=0.40 and 0.50. From low field
magnetization data carried out at different temperatures below TC, HC1 has been
extracted. The plot of HC1 versus temperature shows an anomalous increase at
low temperatures. From high field magnetization hysterisis measurements carried
out in fields up to 16 T at 4.2 K and 20 K, the critical current density has
been evaluated using the Bean critical state model. The JC determined from the
high field data is >104A/cm2 at 4.2 K and 5 T. The superconducting transitions
were also measured resistively in increasing applied magnetic fields up to 12
Tesla. From the variation of the TC onset with applied field, dHC2/dT at TC was
obtained to be -7.708 T/K and -5.57 T/K in the samples with x=0.40 and 0.50.Comment: 14 pages; 7 figure
Popcorn germplasm resistance to fungal diseases caused by Exserohilum turcicum and Bipolaris maydis
Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV
Results are presented from a search for a W' boson using a dataset
corresponding to 5.0 inverse femtobarns of integrated luminosity collected
during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV.
The W' boson is modeled as a heavy W boson, but different scenarios for the
couplings to fermions are considered, involving both left-handed and
right-handed chiral projections of the fermions, as well as an arbitrary
mixture of the two. The search is performed in the decay channel W' to t b,
leading to a final state signature with a single lepton (e, mu), missing
transverse energy, and jets, at least one of which is tagged as a b-jet. A W'
boson that couples to fermions with the same coupling constant as the W, but to
the right-handed rather than left-handed chiral projections, is excluded for
masses below 1.85 TeV at the 95% confidence level. For the first time using LHC
data, constraints on the W' gauge coupling for a set of left- and right-handed
coupling combinations have been placed. These results represent a significant
improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe
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