1,854 research outputs found
A method for finding optimal location for an optometric practice
Students graduating from schools of optometry, and established optometrists who desire to relocate need a systematic approach to determine an optimal location for their practices. This project demonstrates a method of finding that optimal location with an example of its application. The process is compared to performing a complete vision examination including case history, data collection, analysis, diagnosis, and treatment. Key factors considered are personal and professional goals, economics of the potential location, and practice opportunities in the area
The Intrinsic Matter Bispectrum in CDM
We present a fully relativistic calculation of the matter bispectrum at
second order in cosmological perturbation theory assuming a Gaussian primordial
curvature perturbation. For the first time we perform a full numerical
integration of the bispectrum for both baryons and cold dark matter using the
second-order Einstein-Boltzmann code, SONG. We review previous analytical
results and provide an improved analytic approximation for the second-order
kernel in Poisson gauge which incorporates Newtonian nonlinear evolution,
relativistic initial conditions, the effect of radiation at early times and the
cosmological constant at late times. Our improved kernel provides a percent
level fit to the full numerical result at late times for most configurations,
including both equilateral shapes and the squeezed limit. We show that baryon
acoustic oscillations leave an imprint in the matter bispectrum, making a
significant impact on squeezed shapes.Comment: Accepted for publication in JCAP. 17 pages + appendices, 6 figures.
Code available at GitHub: http://github.com/coccoinomane/son
Impact of polarization on the intrinsic cosmic microwave background bispectrum
We compute the cosmic microwave background (CMB) bispectrum induced by the evolution of the primordial density perturbations, including for the first time both temperature and polarization using a second-order Boltzmann code. We show that including polarization can increase the signal-to-noise by a factor 4 with respect to temperature alone. We find the expected signal-to-noise for this intrinsic bispectrum of S=N ¼ 3.8; 2.9; 1.6 and 0.5 for an ideal experiment with an angular resolution of lmax ¼ 3000, the proposed CMB surveys PRISM and COrE, and Planck’s polarized data, respectively; the bulk of this signal comes from E-mode polarization and from squeezed configurations. We discuss how CMB lensing is expected to reduce these estimates as it suppresses the bispectrum for squeezed configurations and contributes to the noise in the estimator. We find that the presence of the intrinsic bispectrum will bias a measurement of primordial non-Gaussianity of local type by fintr NL ¼ 0.66 for an ideal experiment with lmax ¼ 3000. Finally, we verify the robustness of our results by recovering the analytic approximation for the squeezed-limit bispectrum in the general polarized case
Establishing Public Health Security in a Postwar Iraq: Constitutional Obstacles and Lessons for Other Federalizing States
The public health consequences of the conflict in Iraq will likely continue after the violence has subsided. Reestablishing public health security will require large investments in infrastructure and the creation of effective systems of governance. On the question of governance, the allocation of powers in the new constitution of Iraq is critical. Given the ease with which public health threats cross borders, the constitution needs to grant to the federal government the legal authority to manage such threats and simultaneously meet international requirements. Unfortunately, the draft constitution does not accomplish this objective. If politically possible, the constitution should be amended to provide the federal government with this authority. If not possible, the Iraqi federal government would have two options. It could attempt to use alternative constitutional powers, such as national security powers. This option would be contentious and the results uncertain. Alternatively, the federal government could attempt to establish collaborative relationships with regional governments. Residual sectarian tensions create potential problems for this option, however. Reflecting on the Iraqi situation, we conclude that other federalizing countries emerging from conflict should ensure that their constitutions provide the federal government with the necessary authority to manage threats to public health security effectively
Simulation Studies of Nanomagnet-Based Architecture
We report a simulation study on interacting ensembles of Co nanomagnets that
can perform basic logic operations and propagate logic signals, where the state
variable is the magnetization direction. Dipole field coupling between
individual nanomagnets drives the logic functionality of the ensemble and
coordinated arrangements of the nanomagnets allow for the logic signal to
propagate in a predictable way. Problems with the integrity of the logic signal
arising from instabilities in the constituent magnetizations are solved by
introducing a biaxial anisotropy term to the Gibbs magnetic free energy of each
nanomagnet. The enhanced stability allows for more complex components of a
logic architecture capable of random combinatorial logic, including horizontal
wires, vertical wires, junctions, fanout nodes, and a novel universal logic
gate. Our simulations define the focus of scaling trends in nanomagnet-based
logic and provide estimates of the energy dissipation and time per nanomagnet
reversal
Calculation of coercivity of magnetic nanostructures at finite temperatures
We report a finite temperature micromagnetic method (FTM) that allows for the
calculation of the coercive field of arbitrary shaped magnetic nanostructures
at time scales of nanoseconds to years. Instead of directly solving the
Landau-Lifshitz-Gilbert equation, the coercive field is obtained without any
free parameter by solving a non linear equation, which arises from the
transition state theory. The method is applicable to magnetic structures where
coercivity is determined by one thermally activated reversal or nucleation
process. The method shows excellent agreement with experimentally obtained
coercive fields of magnetic nanostructures and provides a deeper understanding
of the mechanism of coercivity.Comment: submitted to Phys. Rev.
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