On the ground--state energy of finite Fermi systems

We study the ground--state shell correction energy of a fermionic gas in a mean--field approximation. Considering the particular case of 3D harmonic trapping potentials, we show the rich variety of different behaviors (erratic, regular, supershells) that appear when the number--theoretic properties of the frequency ratios are varied. For self--bound systems, where the shape of the trapping potential is determined by energy minimization, we obtain accurate analytic formulas for the deformation and the shell correction energy as a function of the particle number $N$. Special attention is devoted to the average of the shell correction energy. We explain why in self--bound systems it is a decreasing (and negative) function of $N$.Comment: 10 pages, 5 figures, 2 table

Impact of knee marker misplacement on gait kinematics of children with cerebral palsy using the Conventional Gait Model — a sensitivity study

Clinical gait analysis is widely used in clinical routine to assess the function of patients with motor disorders. The proper assessment of the patient’s function relies greatly on the repeatability between the measurements. Marker misplacement has been reported as the largest source of variability between measurements and its impact on kinematics is not fully understood. Thus, the purpose of this study was: 1) to evaluate the impact of the misplacement of the lateral femoral epicondyle marker on lower limb kinematics, and 2) evaluate if such impact can be predicted. The kinematic data of 10 children with cerebral palsy and 10 aged-match typical developing children were included. The lateral femoral epicondyle marker was virtually misplaced around its measured position at different magnitudes and directions. The outcome to represent the impact of each marker misplacement on the lower limb was the root mean square deviations between the resultant kinematics from each simulated misplacement and the originally calculated kinematics. Correlation and regression equations were estimated between the root mean square deviation and the magnitude of the misplacement expressed in percentage of leg length. Results indicated that the lower-limb kinematics is highly sensitive to the lateral femoral epicondyle marker misplacement in the anterior-posterior direction. The joint angles most impacted by the anterior-posterior misplacement were the hip internal-external rotation (5.3° per 10 mm), the ankle internal-external rotation (4.4° per 10 mm) and the knee flexion-extension (4.2° per 10 mm). Finally, it was observed that the lower the leg length, the higher the impact of misplacement on kinematics. This impact was predicted by regression equations using the magnitude of misplacement expressed in percentage of leg length. An error below 5° on all joints requires a marker placement repeatability under 1.2% of the leg length. In conclusion, the placement of the lateral femoral epicondyle marker in the antero-posterior direction plays a crucial role on the reliability of gait measurements with the Conventional Gait Model

The molecular basis of social behavior: models, methods and advances.

Elucidating the molecular and neural basis of complex social behaviors such as communal living, division of labor and warfare requires model organisms that exhibit these multi-faceted behavioral phenotypes. Social insects, such as ants, bees, wasps and termites, are attractive models to address this problem, with rich ecological and ethological foundations. However, their atypical systems of reproduction have hindered application of classical genetic approaches. In this review, we discuss how recent advances in social insect genomics, transcriptomics, and functional manipulations have enhanced our ability to observe and perturb gene expression, physiology and behavior in these species. Such developments begin to provide an integrated view of the molecular and cellular underpinnings of complex social behavior

Superfluidity versus Anderson localization in a dilute Bose gas

We consider the motion of a quasi one dimensional beam of Bose-Einstein condensed particles in a disordered region of finite extent. Interaction effects lead to the appearance of two distinct regions of stationary flow. One is subsonic and corresponds to superfluid motion. The other one is supersonic, dissipative and shows Anderson localization. We compute analytically the interaction-dependent localization length. We also explain the disappearance of the supersonic stationary flow for large disordered samples.Comment: 4 pages, 3 figures, final published versio

Predicting self-harm with NEO-PI-R facets

The current study explores the facet level personality predictors of self-harm in a college student sample and compares the facet scores for self-harming students to those in non-harming students. Personality is assessed using the Revised NEO Personality Inventory NEO-PI-R and self-harm is assessed using the Deliberate Self-Harm Inventory (DSHI). Results indicate self-harm can be predicted with four NEO-PI-R facets: E2: Gregariousness, N3: Depression, A3: Altruism, O5: Ideas. Multivariate analysis of variance revealed 10 facets that self-harmers scored significantly different on than their non-harming peers including: N1; Anxiety, O1: Fantasy, A1: Trust, N2: angry hostility, O2: Aesthetics, N3: Depression, N4: Self-consciousness, A4: compliance, N5: Impulsiveness, E5; Excitement-seeking, O5: Ideas, and N6; Vulnerability

Band Distributions for Quantum Chaos on the Torus

Band distributions (BDs) are introduced describing quantization in a toral phase space. A BD is the uniform average of an eigenstate phase-space probability distribution over a band of toral boundary conditions. A general explicit expression for the Wigner BD is obtained. It is shown that the Wigner functions for {\em all} of the band eigenstates can be reproduced from the Wigner BD. Also, BDs are shown to be closer to classical distributions than eigenstate distributions. Generalized BDs, associated with sets of adjacent bands, are used to extend in a natural way the Chern-index characterization of the classical-quantum correspondence on the torus to arbitrary rational values of the scaled Planck constant.Comment: 12 REVTEX page

Essays on Paid Family Leave in the United States

Chapter 1: The first chapter is a literature survey that reviews the empirical research conducted on paid family leave in the United States. This chapter summarizes the documented benefits of paid family leave on women\u27s labor force participation, leave usage, and children\u27s health. Also, evidence that suggests potentially harmful effects of paid family leave is discussed. Possible directions for future research are explored, and the chapter concludes by considering the implementation of a national paid family leave program in the United States. Chapter 2: The second chapter replicates and extends the results of Rossin-Slater et al. (2013). The purpose of this exercise is twofold. First, validating the results of a study that is the foundation of the literature on paid family leave in the U.S. is worthwhile in its own right. Second, extending the work of Rossin-Slater et al. by including later years of data allows me to examine the robustness of the results over time. Third, examining the robustness of Rossin-Slater et al.\u27s work to the choice of other estimation models, bolsters their findings. Furthermore, by extending the analysis to other states that have implemented paid family leave programs (namely New Jersey and Rhode Island), I present evidence that bolsters my claim that California’s paid family leave program (CA-PFL) generates stronger effects than New Jersey’s program (NJ-PFL) or Rhode Island’s (RI-PFL), supporting the decision to focus my empirical investigation in Chapter 3 on CA-PFL alone. This chapter also examines the impact of CA-PFL on women\u27s labor force participation at the extensive margin. Chapter 3: The third chapter estimates the impact of CA-PFL on women\u27s years of schooling and fertility, arguing that CA-PFL is a source of exogenous variation in expectations about future labor force participation for women. If in the absence of paid leave, childbearing and childrearing can lead a mother to reduce or even terminate her time at work by dropping out of the labor force, then California\u27s policy may change expectations about career span. In this chapter, I sketch out a model that shows that the theoretical impact of paid family leave on labor force participation is ambiguous. In addition to addressing the policy debate on whether paid family leave can impact women\u27s educational outcomes and career choices, this study contributes to the literature on the effects of paid leave, and more specifically, on the small literature analyzing the effects of CA-PFL. Much of the research conducted on this policy thus far has focused on its impact on labor force participation (Rossin-Slater et al., 2013, Baum and Ruhm, 2016) and maternal health (Rossin, 2011). I contribute to this literature by exploring the possibility that the program induces increases in schooling investments and impacts the fertility decision. I find that CA-PFL delays, but overall increases, educational investments of young women in California

Fluctuations in the level density of a Fermi gas

We present a theory that accurately describes the counting of excited states of a noninteracting fermionic gas. At high excitation energies the results reproduce Bethe's theory. At low energies oscillatory corrections to the many--body density of states, related to shell effects, are obtained. The fluctuations depend non-trivially on energy and particle number. Universality and connections with Poisson statistics and random matrix theory are established for regular and chaotic single--particle motion.Comment: 4 pages, 1 figur