342 research outputs found
Finite element modeling for analysis of cracked cylindrical pipes
The characteristic properties of shell element with similar shapes are used to generate a so-called super element for the analysis of the crack problems for cylindrical pressure vessels. The formulation is processed by matrix condensation without the involvement of special treatment. This method can deal with various singularity problems and it also presents excellent results to crack problems for cylindrical shell. Especially, the knowledge of the kind of singular order is not necessary in super element generation; it is very economical in terms of computer memory and programming. This method also exhibits versatility to solve the problem of kinked crack at cylindrical shell
Duality of Quasilocal Gravitational Energy and Charges with Non-orthogonal Boundaries
We study the duality of quasilocal energy and charges with non-orthogonal
boundaries in the (2+1)-dimensional low-energy string theory. Quasilocal
quantities shown in the previous work and some new variables arisen from
considering the non-orthogonal boundaries as well are presented, and the boost
relations between those quantities are discussed. Moreover, we show that the
dual properties of quasilocal variables such as quasilocal energy density,
momentum densities, surface stress densities, dilaton pressure densities, and
Neuve-Schwarz(NS) charge density, are still valid in the moving observer's
frame.Comment: 19pages, 1figure, RevTe
The Localization Transition of the Two-Dimensional Lorentz Model
We investigate the dynamics of a single tracer particle performing Brownian
motion in a two-dimensional course of randomly distributed hard obstacles. At a
certain critical obstacle density, the motion of the tracer becomes anomalous
over many decades in time, which is rationalized in terms of an underlying
percolation transition of the void space. In the vicinity of this critical
density the dynamics follows the anomalous one up to a crossover time scale
where the motion becomes either diffusive or localized. We analyze the scaling
behavior of the time-dependent diffusion coefficient D(t) including corrections
to scaling. Away from the critical density, D(t) exhibits universal
hydrodynamic long-time tails both in the diffusive as well as in the localized
phase.Comment: 13 pages, 7 figures
Acclimation to short-term low temperatures in two Eucalyptus globulus clones with contrasting drought resistance
We tested the hypothesis that Eucalyptus
globulus Labill. genotypes that are more resistant to dry
environments might also exhibit higher cold tolerances
than drought-sensitive plants. The effect of low temperatures
was evaluated in acclimated and unacclimated
ramets of a drought-resistant clone (CN5) and a
drought-sensitive clone (ST51) of E. globulus. We
studied the plants’ response via leaf gas exchanges, leaf
water and osmotic potentials, concentrations of soluble
sugars, several antioxidant enzymes and leaf electrolyte
leakage. Progressively lowering air temperatures (from
24/16 to 10/ 2 C, day/night) led to acclimation of both
clones. Acclimated ramets exhibited higher photosynthetic
rates, stomatal conductances and lower membrane
relative injuries when compared to unacclimated ramets.
Moreover, low temperatures led to significant increases
of soluble sugars and antioxidant enzymes activity
(glutathione reductase, ascorbate peroxidase and superoxide
dismutases) of both clones in comparison to plants
grown at control temperature (24/16 C). On the other
hand, none of the clones, either acclimated or not,
exhibited signs of photoinhibition under low temperatures
and moderate light. The main differences in the
responses to low temperatures between the two clones
resulted mainly from differences in carbon metabolism,
including a higher accumulation of soluble sugars in the
drought-resistant clone CN5 as well as a higher capacity
for osmotic regulation, as compared to the droughtsensitive
clone ST51. Although membrane injury data
suggested that both clones had the same inherent
freezing tolerance before and after cold acclimation,
the results also support the hypothesis that the droughtresistant
clone had a greater cold tolerance at intermediate
levels of acclimation than the drought-sensitive
clone. A higher capacity to acclimate in a short period
can allow a clone to maintain an undamaged leaf surface
area along sudden frost events, increasing growt
ND5 gene marker reveals recent population expansion of wild Pearse’s mudskipper (Periophthalmus novemradiatus Hamilton) inhabits Setiu Wetlands in East Peninsular Malaysia
Genetic variation and differences in wild Pearse’s mudskipper Periophthalmus novemradiatus populations from Setiu Wetlands
in East Peninsular Malaysia were analysed using the partial mitochondrial DNA ND5 gene sequences. Among the 91 individuals
sampled from six different localities, 35 novel putative haplotypes of P. novemradiatus were detected. 77% (27) of the
haplotypes were unique sequences, with high level of haplotype diversity (H = 0.875) and low nucleotide diversity (Ď€ =
0.0037), contributing to the overall highly diversified gene pool of the P. novemradiatus. This reflects a large effective
population size with current population expansion, which allows the retention of new alleles in populations. However, due to
insufficient time, the accumulation of deeper divergent groups among haplotypes was not possible. Hap05 is the most dominant
(33%) and widespread haplotype, followed by Hap11 and 31. Low genetic differentiation with high gene flow was detected
between sampling sites, and no pattern for isolation by distance was observed despite being territorial creatures. All sites are
at the top priority for conservation because they possess unique haplotypes that are only present at the respective location.
Further samples collection from other native regions are required to provide full understanding of its genetic distribution and
phylogeographical study over larger scale of geographic regions. Heuristic approach to study other species in this area prior
to gazetting the Setiu Wetlands as state park is required in order to conserve the biodiversity in-situ
Structure of Fat Jets at the Tevatron and Beyond
Boosted resonances is a highly probable and enthusiastic scenario in any
process probing the electroweak scale. Such objects when decaying into jets can
easily blend with the cornucopia of jets from hard relative light QCD states.
We review jet observables and algorithms that can contribute to the
identification of highly boosted heavy jets and the possible searches that can
make use of such substructure information. We also review previous studies by
CDF on boosted jets and its measurements on specific jet shapes.Comment: invited review for a special "Top and flavour physics in the LHC era"
issue of The European Physical Journal C, we invite comments regarding
contents of the review; v2 added references and institutional preprint
number
First Observation of Coherent Production in Neutrino Nucleus Interactions with 2 GeV
The MiniBooNE experiment at Fermilab has amassed the largest sample to date
of s produced in neutral current (NC) neutrino-nucleus interactions at
low energy. This paper reports a measurement of the momentum distribution of
s produced in mineral oil (CH) and the first observation of coherent
production below 2 GeV. In the forward direction, the yield of events
observed above the expectation for resonant production is attributed primarily
to coherent production off carbon, but may also include a small contribution
from diffractive production on hydrogen. Integrated over the MiniBooNE neutrino
flux, the sum of the NC coherent and diffractive modes is found to be (19.5
1.1 (stat) 2.5 (sys))% of all exclusive NC production at
MiniBooNE. These measurements are of immediate utility because they quantify an
important background to MiniBooNE's search for
oscillations.Comment: Submitted to Phys. Lett.
In-plane Hall effect in c-axis-oriented MgB2 thin films
We have measured the longitudinal resistivity and the Hall resistivity in the
ab-plane of highly c-axis-oriented MgB2 thin films. In the normal state, the
Hall coefficient (R_H) behaves as R_H ~ T with increasing temperature (T) up to
130 K and then deviates from that linear T-dependence at higher temperatures.
The T^2 dependence of the cotangent of the Hall angle is only observed above
130 K. The mixed-state Hall effect reveals no sign anomaly over a wide range of
current densities from 10^2 to 10^4 A/cm^2 and for magnetic fields up to 5 T.Comment: 5 pages including 5 figure
Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV
A search for a Higgs boson decaying into two photons is described. The
analysis is performed using a dataset recorded by the CMS experiment at the LHC
from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an
integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross
section of the standard model Higgs boson decaying to two photons. The expected
exclusion limit at 95% confidence level is between 1.4 and 2.4 times the
standard model cross section in the mass range between 110 and 150 GeV. The
analysis of the data excludes, at 95% confidence level, the standard model
Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The
largest excess of events above the expected standard model background is
observed for a Higgs boson mass hypothesis of 124 GeV with a local significance
of 3.1 sigma. The global significance of observing an excess with a local
significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is
estimated to be 1.8 sigma. More data are required to ascertain the origin of
this excess.Comment: Submitted to Physics Letters
Measurement of isolated photon production in pp and PbPb collisions at sqrt(sNN) = 2.76 TeV
Isolated photon production is measured in proton-proton and lead-lead
collisions at nucleon-nucleon centre-of-mass energies of 2.76 TeV in the
pseudorapidity range |eta|<1.44 and transverse energies ET between 20 and 80
GeV with the CMS detector at the LHC. The measured ET spectra are found to be
in good agreement with next-to-leading-order perturbative QCD predictions. The
ratio of PbPb to pp isolated photon ET-differential yields, scaled by the
number of incoherent nucleon-nucleon collisions, is consistent with unity for
all PbPb reaction centralities.Comment: Submitted to Physics Letters
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