66 research outputs found
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Bounds for creep in thick spherical pressure vessels
The creep of a hollow sphere subject to constant internal pressure is considered. A method is derived for obtining a priori upper and lower bounds for the displacement of any point in the spherical body at any time. (TFP
SO(N) Superpotential, Seiberg-Witten Curves and Loop Equations
We consider the exact superpotential of N=1 super Yang-Mills theory with
gauge group SO(N) and arbitrary tree-level polynomial superpotential of one
adjoint Higgs field. A field-theoretic derivation of the glueball
superpotential is given, based on factorization of the N=2 Seiberg-Witten
curve. Following the conjecture of Dijkgraaf and Vafa, the result is matched
with the corresponding SO(N) matrix model prediction. The verification involves
an explicit solution of the first non-trivial loop equation, relating the
spherical free energy to that of the non-orientable surfaces with topology
.Comment: 13 pages; v2: minor typos, one equation adde
More on N=1 Matrix Model Curve for Arbitrary N
Using both the matrix model prescription and the strong-coupling approach, we
describe the intersections of n=0 and n=1 non-degenerated branches for quartic
(polynomial of adjoint matter) tree-level superpotential in N=1 supersymmetric
SO(N)/USp(2N) gauge theories with massless flavors. We also apply the method to
the degenerated branch. The general matrix model curve on the two cases we
obtain is valid for arbitrary N and extends the previous work from
strong-coupling approach. For SO(N) gauge theory with equal massive flavors, we
also obtain the matrix model curve on the degenerated branch for arbitrary N.
Finally we discuss on the intersections of n=0 and n=1 non-degenerated branches
for equal massive flavors.Comment: 36pp; to appear in JHE
(Anti)symmetric matter and superpotentials from IIB orientifolds
We study the IIB engineering of N=1 gauge theories with unitary gauge group
and matter in the adjoint and (anti)symmetric representations. We show that
such theories can be obtained as Z2 orientifolds of Calabi-Yau A2 fibrations,
and discuss the explicit T-duality transformation to an orientifolded
Hanany-Witten construction. The low energy dynamics is described by a geometric
transition of the orientifolded background. Unlike previously studied cases, we
show that the orientifold 5-`plane' survives the transition, thus bringing a
nontrivial contribution to the effective superpotential. We extract this
contribution by using matrix model results and compare with geometric data. A
Higgs branch of our models recovers the engineering of SO/Sp theories with
adjoint matter through an O5-`plane' T-dual to an O6-plane. We show that the
superpotential agrees with that produced by engineering through an O5-`plane'
dual to an O4-plane, even though the orientifold of this second construction is
replaced by fluxes after the transition.Comment: 40 page
Characterization of a Legionella pneumophila gene encoding a lipoprotein antigen
A prominent 19kDa surface antigen of Legionella pneumophila , cloned in Escherichia coli , was found to be intimately associated with peptidoglycan. The DNA region encoding this antigen was mapped on an 11.9kb plasmid by means of deletion analysis and transposon mutagenesis. PhoA + gene fusions, generated by Tn phoA insertions into this region, confirmed the presence of a gene encoding a secreted protein. PhoA + transposon insertions were also associated with loss of the 19 kDa antigen in immunoassay s using a monoclonal antibody (mAb1E9) and the replacement of the 19kDa antigen with larger fusion proteins in immunoblots using Legionella immune serum. A 1540bp PstI fragment carrying the gene was sequenced, and the open reading frame encoding the antigen was identified. The gene encodes a polypeptide 176 amino acid residues long and 18913Da in size. The presence of a signal sequence of 22 amino acids with a consensus sequence for cleavage by signal peptidase II indicates that the antigen is a lipoprotein, and striking similarity with peptidoglycan-associated lipoproteins (PALs) from E. coli (51% amino acid homology) and Haemophilus influenzae (55% homology) is noted. We conclude that the 19kDa antigen of L. pneumophila is the structural equivalent of the PAL found in other Gram-negative species and suggest that its post-translational acylation may explain its potency as an immunogen.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75712/1/j.1365-2958.1991.tb00824.x.pd
Random Convex Hulls and Extreme Value Statistics
In this paper we study the statistical properties of convex hulls of
random points in a plane chosen according to a given distribution. The points
may be chosen independently or they may be correlated. After a non-exhaustive
survey of the somewhat sporadic literature and diverse methods used in the
random convex hull problem, we present a unifying approach, based on the notion
of support function of a closed curve and the associated Cauchy's formulae,
that allows us to compute exactly the mean perimeter and the mean area enclosed
by the convex polygon both in case of independent as well as correlated points.
Our method demonstrates a beautiful link between the random convex hull problem
and the subject of extreme value statistics. As an example of correlated
points, we study here in detail the case when the points represent the vertices
of independent random walks. In the continuum time limit this reduces to
independent planar Brownian trajectories for which we compute exactly, for
all , the mean perimeter and the mean area of their global convex hull. Our
results have relevant applications in ecology in estimating the home range of a
herd of animals. Some of these results were announced recently in a short
communication [Phys. Rev. Lett. {\bf 103}, 140602 (2009)].Comment: 61 pages (pedagogical review); invited contribution to the special
issue of J. Stat. Phys. celebrating the 50 years of Yeshiba/Rutgers meeting
Measurement of B(D_s+ -> mu+ nu_mu)/B(D_s+ -> phi mu+ nu_mu) and Determination of the Decay Constant f_{D_s}
We have observed purely-leptonic decays of
from a sample of muonic one prong decay events
detected in the emulsion target of Fermilab experiment E653. Using the yield measured previously in this experiment, we obtain
. In addition, we extract the decay constant .Comment: 15 pages including one figur
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Bounds and limit theorems for secondary creep in symmetric pressure vessels
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THE TEMPERATURE DEPENDENCE OF THE SPECIFIC HEAT AND ENTROPY OF CeAl3
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[(MeC{sub 5}H{sub 4}){sub 3}U]{sub 2}[{mu}-1,4-N{sub2}C{sub 6}H{sub 4}]: A Bimetallic Molecule with Antiferromagnetic Coupling between the Uranium Centers
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