3,938 research outputs found
Network growth model with intrinsic vertex fitness
© 2013 American Physical SocietyWe study a class of network growth models with attachment rules governed by intrinsic node fitness. Both the individual node degree distribution and the degree correlation properties of the network are obtained as functions of the network growth rules. We also find analytical solutions to the inverse, design, problems of matching the growth rules to the required (e.g., power-law) node degree distribution and more generally to the required degree correlation function. We find that the design problems do not always have solutions. Among the specific conditions on the existence of solutions to the design problems is the requirement that the node degree distribution has to be broader than a certain threshold and the fact that factorizability of the correlation functions requires singular distributions of the node fitnesses. More generally, the restrictions on the input distributions and correlations that ensure solvability of the design problems are expressed in terms of the analytical properties of their generating functions
Synchronization of Estrus in the Ewe
Synchronization of estrus has been attempted by using hormone or hormone-like substances to bring females into estrus simultaneously. The objective of a synchronization program is to maniupulate the reproductive processes so that all females may be bred dring a short predefined interval with normal fertility at this breeding. Estrous control through synchronization offers the possibility of more uniform offspring, better use of facilities and labor, concentration of parturition and, in particular, the better utilization of outstanding sires through artificial insemination
Construction of n-Lie algebras and n-ary Hom-Nambu-Lie algebras
We present a procedure to construct (n+1)-Hom-Nambu-Lie algebras from
n-Hom-Nambu-Lie algebras equipped with a generalized trace function. It turns
out that the implications of the compatibility conditions, that are necessary
for this construction, can be understood in terms of the kernel of the trace
function and the range of the twisting maps. Furthermore, we investigate the
possibility of defining (n+k)-Lie algebras from n-Lie algebras and a k-form
satisfying certain conditions
On the Origin of the Early Solar System Radioactivities. Problems with the AGB and Massive Star Scenarios
Recent improvements in stellar models for intermediate-mass and massive stars
are recalled, together with their expectations for the synthesis of radioactive
nuclei of lifetime Myr, in order to re-examine the origins
of now extinct radioactivities, which were alive in the solar nebula. The
Galactic inheritance broadly explains most of them, especially if -process
nuclei are produced by neutron star merging according to recent models.
Instead, Al, Ca, Cs and possibly Fe require
nucleosynthesis events close to the solar formation. We outline the persisting
difficulties to account for these nuclei by Intermediate Mass Stars (2
M/M). Models of their final stages now
predict the ubiquitous formation of a C reservoir as a neutron capture
source; hence, even in presence of Al production from Deep Mixing or Hot
Bottom Burning, the ratio Al/Pd remains incompatible with
measured data, with a large excess in Pd. This is shown for two recent
approaches to Deep Mixing. Even a late contamination by a Massive Star meets
problems. In fact, inhomogeneous addition of Supernova debris predicts
non-measured excesses on stable isotopes. Revisions invoking specific low-mass
supernovae and/or the sequential contamination of the pre-solar molecular cloud
might be affected by similar problems, although our conclusions here are
weakened by our schematic approach to the addition of SN ejecta. The limited
parameter space remaining to be explored for solving this puzzle is discussed.Comment: Accepted for publication on Ap
Embedding of theories with SU(2|4) symmetry into the plane wave matrix model
We study theories with SU(2|4) symmetry, which include the plane wave matrix
model, 2+1 SYM on RxS^2 and N=4 SYM on RxS^3/Z_k. All these theories possess
many vacua. From Lin-Maldacena's method which gives the gravity dual of each
vacuum, it is predicted that the theory around each vacuum of 2+1 SYM on RxS^2
and N=4 SYM on RxS^3/Z_k is embedded in the plane wave matrix model. We show
this directly on the gauge theory side. We clearly reveal relationships among
the spherical harmonics on S^3, the monopole harmonics and the harmonics on
fuzzy spheres. We extend the compactification (the T-duality) in matrix models
a la Taylor to that on spheres.Comment: 56 pages, 6 figures, v2:a footnote and references added, section 5.2
improved, typos corrected, v3:typos corrected, v4: some equations are
corrected, eq.(G.2) is added, conclusion is unchange
M Theory As A Matrix Model: A Conjecture
We suggest and motivate a precise equivalence between uncompactified eleven
dimensional M-theory and the N = infinity limit of the supersymmetric matrix
quantum mechanics describing D0-branes. The evidence for the conjecture
consists of several correspondences between the two theories. As a consequence
of supersymmetry the simple matrix model is rich enough to describe the
properties of the entire Fock space of massless well separated particles of the
supergravity theory. In one particular kinematic situation the leading large
distance interaction of these particles is exactly described by supergravity .
The model appears to be a nonperturbative realization of the holographic
principle. The membrane states required by M-theory are contained as
excitations of the matrix model. The membrane world volume is a noncommutative
geometry embedded in a noncommutative spacetime.Comment: Typo and tex error corrected. 41 pages, harvma
Discontinuation of reflex testing of stool samples for vancomycin-resistant enterococci resulted in increased prevalence
Discontinuation of reflex testing stool submitted for Clostridium difficile testing for vancomycin-resistant enterococci (VRE) led to an increase of patients with healthcare-associated VRE bacteremia and bacteriuria (2.1 versus 3.6 per 10,000 patient days; p<0.01 ). Cost-benefit analysis showed reflex screening and isolation of VRE reduced hospital costs
Ternary q-Virasoro-Witt Hom-Nambu-Lie algebras
In this paper we construct ternary -Virasoro-Witt algebras which
-deform the ternary Virasoro-Witt algebras constructed by Curtright, Fairlie
and Zachos using enveloping algebra techniques. The ternary
Virasoro-Witt algebras constructed by Curtright, Fairlie and Zachos depend on a
parameter and are not Nambu-Lie algebras for all but finitely many values of
this parameter. For the parameter values for which the ternary Virasoro-Witt
algebras are Nambu-Lie, the corresponding ternary -Virasoro-Witt algebras
constructed in this article are also Hom-Nambu-Lie because they are obtained
from the ternary Nambu-Lie algebras using the composition method. For other
parameter values this composition method does not yield Hom-Nambu Lie algebra
structure for -Virasoro-Witt algebras. We show however, using a different
construction, that the ternary Virasoro-Witt algebras of Curtright, Fairlie and
Zachos, as well as the general ternary -Virasoro-Witt algebras we construct,
carry a structure of ternary Hom-Nambu-Lie algebra for all values of the
involved parameters
A Note on Classical Solution of Chaplygin-gas as D-brane
The classical solution of bosonic d-brane in (d+1,1) space-time is studied.
We work with light-cone gauge and reduce the problem into Chaplygin gas
problem. The static equation is equivalent to vanishing of extrinsic mean
curvature, which is similar to Einstein equation in vacuum. We show that the
d-brane problem in this gauge is closely related to Plateau problem, and we
give some non-trivial solutions from minimal surfaces. The solutions of
d-1,d,d+1 spatial dimensions are obtained from d-dimensional minimal surfaces
as solutions of Plateau problem. In addition we discuss on the relation to
Hamiltonian-BRST formalism for d-branes.Comment: 20 pages,No figures, Latex, Address change
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