RECRUITING CRISIS: ANALYSIS OF NAVY RECRUITING DEFICIENCIES IN 2022 AND BEYOND

Fiscal Year 2022 was described by senior military officials as one of the most difficult recruiting years since the end of conscription service in 1973. All services within the Department of Defense struggled to achieve or failed to meet assigned accession goals in Fiscal Year 2022 and officials predict that Fiscal Year 2023 will pose an even bigger challenge due to year over year accession goal increases and the depletion of future accessions from delayed entry pools. This thesis identifies systemic and emergent challenges specific to the United States Navy recruiting mission. Countless studies have identified challenges such as national unemployment rate and other economic factors, rising obesity and other medical trends in the American population, and war-time actions or military operations as contributors to recruiting difficulties. Using a qualitative analysis approach, I provide an in-depth description of the Navy recruiting structure, analyze past literature to identify factors causing recruiting challenges, and compile responses gathered from interviews with Navy Talent Acquisition Group leaders from across the enterprise. The findings indicate that manpower deficiencies, advertising shortcomings, the job market, recruiting transformation, high school access, the political environment, and low propensity to serve are all contributors to recruiting struggles. Future analysis of policies to counteract these external factors is highly recommended.Lieutenant Commander, United States NavyApproved for public release. Distribution is unlimited

Triplet proximity effect and odd-frequency pairing in graphene

We study the interplay between proximity-induced superconductivity and ferromagnetism in graphene by self-consistently solving the Bogoliubov-de Gennes equations on the honeycomb lattice. We find that a strong triplet proximity effect is generated in graphene, leading to odd-frequency pairing correlations. These odd-frequency correlations are clearly manifested in the local density of states of the graphene sheet, which can be probed via STM-measurements. Motivated by recent experiments on S$\mid$N$\mid$S graphene Josephson junctions, we also study the spectrum of Andreev-bound states formed in the normal region due to the proximity effect. Our results may be useful for interpreting spectroscopic data and can also serve as a guideline for future experiments.Comment: 4 pages, 3 figures. Submitted to Physical Review

Does Subsidizing Fertilizer Increase Yields? Evidence from Malawi

Despite their strain on government and donor budgets, fertilizer subsidies have once again become popular policy tools in several Sub-Saharan Africa countries as a potential way to increase yields in staple crops like maize. Policy makers often assume that farmers who receive the subsidy will achieve yield responses that are similar to those obtained by farmers who pay commercial prices for the input. This notion has not been verified empirically. Our study uses panel data from Malawi, a country that recently implemented a fertilizer subsidy program, to compare maize yield response to fertilizer from farmers who received subsidized fertilizer with yield responses from those who paid commercial prices for the input. Descriptive results indicate that maize plots using commercial fertilizer obtain higher yields per kilogram of fertilizer than maize plots that used subsidized fertilizer. Conversely, the results obtained using a fixed-effects estimator indicate that when other factors are controlled for, maize plots that use subsidized fertilizer obtain a higher yield response than other plots. The results seems to be influenced by a group of farmers who used no fertilizer before the subsidy program began, but used subsidized fertilizer after the program was implemented. This group of farmers obtained significantly higher yields in the year when they receive the subsidy than did the rest of the farmers in the sample during that year. These findings indicate that in order to be effective, government officials should specifically target fertilizer subsidies to farmers who lack access to commercial markets or would not otherwise find it profitable to purchase the input.Malawi, Fertilizer Subsidies, Production Function, Crop Production/Industries,

Josephson current in graphene: the role of unconventional pairing symmetries

We investigate the Josephson current in a graphene superconductor/normal/superconductor junction, where superconductivity is induced by means of the proximity effect from external contacts. We take into account the possibility of anisotropic pairing by also including singlet nearest-neighbor interactions, and investigate how the transport properties are affected by the symmetry of the superconducting order parameter. This corresponds to an extension of the usual on-site interaction assumption, which yields an isotropic s-wave order parameter near the Dirac points. Here, we employ a full numerical solution as well as an analytical treatment, and show how the proximity effect may induce exotic types of superconducting states near the Dirac points, e.g. $p_x$- and $p_y$-wave pairing or a combination of s-wave and p+\i p-wave pairing. We find that the Josephson current exhibits a weakly-damped, oscillatory dependence on the length of the junction when the graphene sheet is strongly doped. The analytical and numerical treatments are found to agree well with each other in the s-wave case when calculating the critical current and current-phase relationship. For the scenarios with anisotropic superconducting pairing, there is a deviation between the two treatments, especially for the effective $p_x$-wave order parameter near the Dirac cones which features zero-energy states at the interfaces. This indicates that a numerical, self-consistent approach becomes necessary when treating anisotropic superconducting pairing in graphene.Comment: 15 pages, 12 figure

Strongly anharmonic current-phase relation in ballistic graphene Josephson junctions

Motivated by a recent experiment directly measuring the current-phase relation (CPR) in graphene under the influence of a superconducting proximity effect, we here study the temperature dependence of the CPR in ballistic graphene SNS Josephson junctions within the the self-consistent tight-binding Bogoliubov-de Gennes (BdG) formalism. By comparing these results with the standard Dirac-BdG method, where rigid boundary conditions are assumed at the SN interfaces, we show on a crucial importance of both proximity effect and depairing by current for the CPR. The proximity effect grows with temperature and reduces the skewness of the CPR towards the harmonic result. In short junctions ($L<\xi$) current depairing is also important and gives rise to a critical phase $\phi_c<\pi/2$ over a wide range of temperatures and doping levels.Comment: 7 pages, 4 figures. v2 contains very minor change

Majorana fermions in spin-orbit coupled ferromagnetic Josephson junctions

We study all possible Majorana modes in two-dimensional spin-orbit coupled ferromagnetic superconductor-normal state-superconductor (SNS) Josephson junctions and propose experiments to detect them. With the S region in a non-trivial topological phase and a superconducting phase difference $\phi = \pi$ across the junction, two delocalized Majorana fermions with no excitation gap appear in the N region. In addition, if S and N belong to different topological phases and have well-separated the Fermi surfaces, localized Majorana fermions with a finite excitation gap also emerge at both SN interfaces for all $\phi$.Comment: 4 pages, 3 figures. Published versio