12,507 research outputs found
One Out of Every Five: Teen Mothers and Subsequent Childbearing
The birth of a child to a teenager puts the young family at risk for negative social and health consequences; the birth of additional children can further impede the family's financial, academic, and social success. Though there is a national interest in reducing the teen birth rate, strategies designed to achieve this goal often insufficiently target a readily identifiable group -teens who are already mothers. Of those programs that do target teen mothers, few have been able to demonstrate success. Teen mothers should be targeted for pregnancy prevention not only because they contribute to the teen birth rate with its attendant consequences, but also because second and higher-order births to teenaged mothers often limits life options further than having only one child.Compared to a teen mother with one child, a teenager with two or more children typically faces: lower educational attainment;greater likelihood of poverty; andimpaired health for the infant
Impact of Electron-Electron Cusp on Configuration Interaction Energies
The effect of the electron-electron cusp on the convergence of configuration
interaction (CI) wave functions is examined. By analogy with the
pseudopotential approach for electron-ion interactions, an effective
electron-electron interaction is developed which closely reproduces the
scattering of the Coulomb interaction but is smooth and finite at zero
electron-electron separation. The exact many-electron wave function for this
smooth effective interaction has no cusp at zero electron-electron separation.
We perform CI and quantum Monte Carlo calculations for He and Be atoms, both
with the Coulomb electron-electron interaction and with the smooth effective
electron-electron interaction. We find that convergence of the CI expansion of
the wave function for the smooth electron-electron interaction is not
significantly improved compared with that for the divergent Coulomb interaction
for energy differences on the order of 1 mHartree. This shows that, contrary to
popular belief, description of the electron-electron cusp is not a limiting
factor, to within chemical accuracy, for CI calculations.Comment: 11 pages, 6 figures, 3 tables, LaTeX209, submitted to The Journal of
Chemical Physic
Dynamical Monte Carlo Study of Equilibrium Polymers : Static Properties
We report results of extensive Dynamical Monte Carlo investigations on
self-assembled Equilibrium Polymers (EP) without loops in good solvent. (This
is thought to provide a good model of giant surfactant micelles.) Using a novel
algorithm we are able to describe efficiently both static and dynamic
properties of systems in which the mean chain length \Lav is effectively
comparable to that of laboratory experiments (up to 5000 monomers, even at high
polymer densities). We sample up to scission energies of over
nearly three orders of magnitude in monomer density , and present a
detailed crossover study ranging from swollen EP chains in the dilute regime up
to dense molten systems. Confirming recent theoretical predictions, the
mean-chain length is found to scale as \Lav \propto \phi^\alpha \exp(\delta
E) where the exponents approach
and in the
dilute and semidilute limits respectively. The chain length distribution is
qualitatively well described in the dilute limit by the Schulz-Zimm
distribution \cN(s)\approx s^{\gamma-1} \exp(-s) where the scaling variable
is s=\gamma L/\Lav. The very large size of these simulations allows also an
accurate determination of the self-avoiding walk susceptibility exponent
. ....... Finite-size effects are discussed in
detail.Comment: 15 pages, 14 figures, LATE
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Examining the Benefits of Project Management Professional (PMP) Certification for IS Project Managers and Organizations
The project management professional (PMP) certification has gained a positive reputation among project managers as well as with HR managers and recruiters. However, the organizational benefits are untested. This paper examines the business value of PMP certification. The three questions this study investigates are, What value does certification give project managers? What value does certification give organizations? and How can organizations encourage project managers to pursue certification? Content analysis of transcripts from twenty-five structured interviews identified several reasons businesses should encourage their project managers to pursue PMP certification, but many of the benefits are not easily quantified
Mechanical compatibility of sol–gel annealing with titanium for orthopaedic prostheses
Sol–gel processing is an attractive method for large-scale surface coating due to its facile and inexpensive preparation, even with the inclusion of precision nanotopographies. These are desirable traits for metal orthopaedic prostheses where ceramic coatings are known to be osteoinductive and the effects may be amplified through nanotexturing. However there are a few concerns associated with the application of sol–gel technology to orthopaedics. Primarily, the annealing stage required to transform the sol–gel into a ceramic may compromise the physical integrity of the underlying metal. Secondly, loose particles on medical implants can be carcinogenic and cause inflammation so the coating needs to be strongly bonded to the implant. These concerns are addressed in this paper. Titanium, the dominant material for orthopaedics at present, is examined before and after sol–gel processing for changes in hardness and flexural modulus. Wear resistance, bending and pull tests are also performed to evaluate the ceramic coating. The findings suggest that sol–gel coatings will be compatible with titanium implants for an optimum temperature of 500 °C
What physical exam techniques are useful to detect malingering?
No examination technique objectively proves malingering (strength of recommendation [SOR]: C, expert opinion). Waddell's signs are associated with poor treatment outcomes but cannot discriminate organic from nonorganic causes (SOR: B, systematic review
of low-quality studies). Hoover's and the Abductor sign indicate nonorganic paralysis (SOR: C, small, lower-quality case-control studies)
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