4,785 research outputs found
PREDICTIVE VARIABLES AND CAREER PATHS FOR SELECTION TO LIEUTENANT COLONEL COMMAND WITHIN THE MARINE CORPS
In this thesis, I study the predictive variables and career paths associated with selection to lieutenant colonel command within the Marine Corps. Previous research analyzed the lieutenant colonel command screening board (CSB), but none have focused on an officer’s career path and its effect on lieutenant colonel command selection. First, I determine the variables associated for selection to lieutenant colonel in three different populations contained within the data. I then analyze which career paths for the infantry, artillery, tank, and assault amphibious vehicle officer military occupational specialties (MOS) are predictive for selection to lieutenant colonel command. I applied logit multivariate models to CSB data from FY 2015 and FY 2017–2022 to determine these variables and career paths. My findings suggest command selection is associated with physical fitness, Fitness Report evaluations, and resident major professional military education. Regarding predictive career paths, captains who fill a b-billet associated with their primary MOS have an increased probability of selection for lieutenant colonel command. Individual b-billets positively correlated with command selection include Tactical Training Exercise Control Group as a captain, Expeditionary Warfare School instructor as a major, and a Recruiting Station Commanding Officer. Additionally, possessing the additional MOSs of Operational Planner is positively correlated with lieutenant colonel command selection.Major, United States Marine CorpsApproved for public release. Distribution is unlimited
Competing epidemics on complex networks
Human diseases spread over networks of contacts between individuals and a
substantial body of recent research has focused on the dynamics of the
spreading process. Here we examine a model of two competing diseases spreading
over the same network at the same time, where infection with either disease
gives an individual subsequent immunity to both. Using a combination of
analytic and numerical methods, we derive the phase diagram of the system and
estimates of the expected final numbers of individuals infected with each
disease. The system shows an unusual dynamical transition between dominance of
one disease and dominance of the other as a function of their relative rates of
growth. Close to this transition the final outcomes show strong dependence on
stochastic fluctuations in the early stages of growth, dependence that
decreases with increasing network size, but does so sufficiently slowly as
still to be easily visible in systems with millions or billions of individuals.
In most regions of the phase diagram we find that one disease eventually
dominates while the other reaches only a vanishing fraction of the network, but
the system also displays a significant coexistence regime in which both
diseases reach epidemic proportions and infect an extensive fraction of the
network.Comment: 14 pages, 5 figure
Snell's Law for a vortex dipole in a Bose-Einstein condensate
A quantum vortex dipole, comprised of a closely bound pair of vortices of
equal strength with opposite circulation, is a spatially localized travelling
excitation of a planar superfluid that carries linear momentum, suggesting a
possible analogy with ray optics. We investigate numerically and analytically
the motion of a quantum vortex dipole incident upon a step-change in the
background superfluid density of an otherwise uniform two-dimensional
Bose-Einstein condensate. Due to the conservation of fluid momentum and energy,
the incident and refracted angles of the dipole satisfy a relation analogous to
Snell's law, when crossing the interface between regions of different density.
The predictions of the analogue Snell's law relation are confirmed for a wide
range of incident angles by systematic numerical simulations of the
Gross-Piteavskii equation. Near the critical angle for total internal
reflection, we identify a regime of anomalous Snell's law behaviour where the
finite size of the dipole causes transient capture by the interface.
Remarkably, despite the extra complexity of the surface interaction, the
incoming and outgoing dipole paths obey Snell's law.Comment: 16 pages, 7 figures, Scipost forma
Tuning the interactions of spin-polarized fermions using quasi-one-dimensional confinement
The behavior of ultracold atomic gases depends crucially on the two-body
scattering properties of these systems. We develop a multichannel scattering
theory for atom-atom collisions in quasi-one-dimensional (quasi-1D) geometries
such as atomic waveguides or highly elongated traps. We apply our general
framework to the low energy scattering of two spin-polarized fermions and show
that tightly-confined fermions have infinitely strong interactions at a
particular value of the 3D, free-space p-wave scattering volume. Moreover, we
describe a mapping of this strongly interacting system of two quasi-1D fermions
to a weakly interacting system of two 1D bosons.Comment: Submitted to Phys. Rev. Let
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Spinal Progenitor-Laden Bridges Support Earlier Axon Regeneration Following Spinal Cord Injury.
Impact statementSpinal cord injury (SCI) results in loss of tissue innervation below the injury. Spinal progenitors have a greater ability to repair the damage and can be injected into the injury, but their regenerative potential is hampered by their poor survival after transplantation. Biomaterials can create a cell delivery platform and generate a more hospitable microenvironment for the progenitors within the injury. In this work, polymeric bridges are used to deliver embryonic spinal progenitors to the injury, resulting in increased progenitor survival and subsequent regeneration and functional recovery, thus demonstrating the importance of combined therapeutic approaches for SCI
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