30,373 research outputs found
A solution procedure for behavior of thick plates on a nonlinear foundation and postbuckling behavior of long plates
Approximate solutions for three nonlinear orthotropic plate problems are presented: (1) a thick plate attached to a pad having nonlinear material properties which, in turn, is attached to a substructure which is then deformed; (2) a long plate loaded in inplane longitudinal compression beyond its buckling load; and (3) a long plate loaded in inplane shear beyond its buckling load. For all three problems, the two dimensional plate equations are reduced to one dimensional equations in the y-direction by using a one dimensional trigonometric approximation in the x-direction. Each problem uses different trigonometric terms. Solutions are obtained using an existing algorithm for simultaneous, first order, nonlinear, ordinary differential equations subject to two point boundary conditions. Ordinary differential equations are derived to determine the variable coefficients of the trigonometric terms
Analysis techniques for multivariate root loci
Analysis and techniques are developed for the multivariable root locus and the multivariable optimal root locus. The generalized eigenvalue problem is used to compute angles and sensitivities for both types of loci, and an algorithm is presented that determines the asymptotic properties of the optimal root locus
Infrared astronomy research and high altitude observations
Highlights are presented of studies of the emission mechanisms in the 4 to 8 micron region of the spectrum using a circular variable filter wheel spectrometer with a PbSnTe photovoltaic detector. Investigations covered include the spectroscopy of planets, stellar atmospheres, highly obscured objects in molecular clouds, planetary nebulae, H2 regions, and extragalactic objects
The timing of maternal depressive symptoms and child cognitive development: a longitudinal study.
Background: Maternal depression is known to be associated with impairments in child cognitive development, although the effect of timing of exposure to maternal depression is unclear. Methods: Data collected for the Avon Longitudinal Study of Parents and Children, a longitudinal study beginning in pregnancy, included self-report measures of maternal depression the Edinburgh Postnatal Depression Scale, completed on 6 occasions up to 3 years of age, and IQ of the index child (WISC) measured at aged 8 years. We used these data to assign women to 8 groups according to whether depression occurred in the antenatal, postnatal, preschool period, any combination of these times, or not at all. We compared a model comprising all patterns of depression (saturated model) with models nested within this to test whether there is a relationship between depression and child cognitive development and, if so, whether there is a sensitive period. We then investigated the relationship with child IQ for each model, following adjustment for confounders. Results: Six thousand seven hundred and thirty-five of 13,615 children from singleton births (49.5%, of eligible core sample) attended a research clinic at 8 years and completed a WISC with a score ≥ 70. A total of 5,029 mothers of these children had completed mood assessments over the 3 time periods. In unadjusted analyses, all three sensitive period models were as good as the saturated model, as was an accumulation model. Of the sensitive period models, only that for antenatal exposure was a consistently better fit than the accumulation model. After multiple imputation for missing data (to n = 6,735), there was no effect of postnatal depression on child IQ independent of depression at other times [-0.19 IQ points, 95% confidence interval (CI) -1.5 to 1.1 points]. There was an effect of antenatal depression (-3.19 IQ points, 95% CI: -4.33 to -2.06) which attenuated following adjustment (-0.64 IQ points, 95% CI: -1.68 to 0.40). Conclusions: The postnatal period is not a sensitive one for the effect of maternal depression on child cognitive development. © 2011 The Authors. Journal of Child Psychology and Psychiatry
A stochastic perturbation of inviscid flows
We prove existence and regularity of the stochastic flows used in the
stochastic Lagrangian formulation of the incompressible Navier-Stokes equations
(with periodic boundary conditions), and consequently obtain a
\holderspace{k}{\alpha} local existence result for the Navier-Stokes
equations. Our estimates are independent of viscosity, allowing us to consider
the inviscid limit. We show that as , solutions of the stochastic
Lagrangian formulation (with periodic boundary conditions) converge to
solutions of the Euler equations at the rate of .Comment: 13 pages, no figures
On the Fourier transform of the characteristic functions of domains with -smooth boundary
We consider domains with -smooth boundary and
study the following question: when the Fourier transform of the
characteristic function belongs to ?Comment: added two references; added footnotes on pages 6 and 1
Breakdown of Strong-Coupling Perturbation Theory in Doped Mott Insulators
We show that doped Mott insulators, such as the copper-oxide superconductors,
are asymptotically slaved in that the quasiparticle weight, , near
half-filling depends critically on the existence of the high energy scale set
by the upper Hubbard band. In particular, near half filling, the following
dichotomy arises: when the high energy scale is integrated out but Z=0
in the thermodynamic limit when it is retained. Slavery to the high energy
scale arises from quantum interference between electronic excitations across
the Mott gap. Broad spectral features seen in photoemission in the normal state
of the cuprates are argued to arise from high energy slavery.Comment: Published versio
Influence of Larval Gizzard Shad (Dorosoma cepedianum) Density on Piscivory and Growth of Young-of-Year Saugeye (Stizostedion vitreum x S. canadense)
Abstract in English and French.Growth and survival of young-of-year saugeye (Stizostedion vitreum x S. canadense) (stocked into Ohio reservoirs to create sport fisheries) are probably influenced by prey availability, variations in which may
account for historically documented variability in stocking success. Because saugeye switch from a diet of
zooplankton to fish once stocked, we sought to determine experimentally if saugeye size and available ichthyoplankton,
i.e., larval gizzard shad (Borosoma cepediaraum), affected this switch and whether piscivory improved saugeye growth. In an enclosure experiment, saugeye (33.9 mm TL) immediately switched to
piscivory when exposed to ichthyoplankton densities of 20 and l00m^-3, growing faster when more gizzard shad were available. In another enclosure experiment, saugeye 30-49 mm TL consumed 14-mm gizzard shad. In ponds (N = 4 ponds-treatment-1) containing zooplankton and chironornids, we compared
saugeye growth with and without larval gizzard shad and found, as in the first enclosure experiment, that piscivory improved saugeye growth. Neither saugeye size nor ichthyoplankton density influenced
how quickly saugeye switched to piscivory. We conclude that managers should stock saugeye >=30 mm 1-2 wk before peak ichthyoplankton densities to improve saugeye growth and survival by enhancing
opportunities for exploitation of young-of-yeas gizzard shad.This work was funded by the Federal Aid in Sport Fish Restoration Program (F-57-R, Evaluation of Fish Management Techniques),
administered jointly by the U.S. Fish and Wildlife Service and the Ohio Division of Wildlife
Conservative Quantum Computing
Conservation laws limit the accuracy of physical implementations of
elementary quantum logic gates. If the computational basis is represented by a
component of spin and physical implementations obey the angular momentum
conservation law, any physically realizable unitary operators with size less
than n qubits cannot implement the controlled-NOT gate within the error
probability 1/(4n^2), where the size is defined as the total number of the
computational qubits and the ancilla qubits. An analogous limit for bosonic
ancillae is also obtained to show that the lower bound of the error probability
is inversely proportional to the average number of photons. Any set of
universal gates inevitably obeys a related limitation with error probability
O(1/n^2)$. To circumvent the above or related limitations yielded by
conservation laws, it is recommended that the computational basis should be
chosen as the one commuting with the additively conserved quantities.Comment: 5 pages, RevTex. Corrected to include a new statement that for
bosonic ancillae the lower bound of the error probability is inversely
proportional to the average number of photons, kindly suggested by Julio
Gea-Banacloch
Entanglement in bosonic systems
We present a technique to resolve a Gaussian density matrix and its time
evolution through known expectation values in position and momentum. Further we
find the full spectrum of this density matrix and apply the technique to a
chain of harmonic oscillators to find agreement with conformal field theory in
this domain. We also observe that a non-conformal state has a divergent
entanglement entropy.Comment: 7 pages, 6 figure
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