Synthetic aperture radar images of ocean waves, theories of imaging physics and experimental tests

The physical mechanism for the synthetic Aperture Radar (SAR) imaging of ocean waves is investigated through the use of analytical models. The models are tested by comparison with data sets from the SEASAT mission and airborne SAR's. Dominant ocean wavelengths from SAR estimates are biased towards longer wavelengths. The quasispecular scattering mechanism agrees with experimental data. The Doppler shift for ship wakes is that of the mean sea surface

Protecting the SWAP\sqrt{SWAP} operation from general and residual errors by continuous dynamical decoupling

We study the occurrence of errors in a continuously decoupled two-qubit state during a $\sqrt{SWAP}$ quantum operation under decoherence. We consider a realization of this quantum gate based on the Heisenberg exchange interaction, which alone suffices for achieving universal quantum computation. Furthermore, we introduce a continuous-dynamical-decoupling scheme that commutes with the Heisenberg Hamiltonian to protect it from the amplitude damping and dephasing errors caused by the system-environment interaction. We consider two error-protection settings. One protects the qubits from both amplitude damping and dephasing errors. The other features the amplitude damping as a residual error and protects the qubits from dephasing errors only. In both settings, we investigate the interaction of qubits with common and independent environments separately. We study how errors affect the entanglement and fidelity for different environmental spectral densities.Comment: Extended version of arXiv:1005.1666. To appear in PR

Nonlinear metrology with a quantum interface

We describe nonlinear quantum atom-light interfaces and nonlinear quantum metrology in the collective continuous variable formalism. We develop a nonlinear effective Hamiltonian in terms of spin and polarization collective variables and show that model Hamiltonians of interest for nonlinear quantum metrology can be produced in $^{87}$Rb ensembles. With these Hamiltonians, metrologically relevant atomic properties, e.g. the collective spin, can be measured better than the "Heisenberg limit" $\propto 1/N$. In contrast to other proposed nonlinear metrology systems, the atom-light interface allows both linear and non-linear estimation of the same atomic quantities.Comment: 8 pages, 1 figure

ANALYTICAL AND NUMERICAL MODELS FOR THE AERODYNAMIC NOISE PREDICTION OF AN HIGH-SPEED TRAIN PANTOGRAPH

The present work deals with the aeroacoustic analysis of a three-dimensional pantograph model, through the employment of an innovative analytical approach and a 3D numerical modeling. Specifically, the proposed analytical approach, aimed to predict the noise emission, is based on a modified formulation of the Smith and Chow's formula. Namely, by considering the entire landing gear structure as a sum of cylindrical elements, each cylinder noise has been individually calculated by the formula, as a result, based on the superposition principle, the whole noise is obtained; considering that the pantograph can also be considered as a sum of cylindrical elements, this formula, initially developed for aircraft landing gears, has been optimized and calibrated for the purpose of the present study. Because of, the analytical formula does not take obviously into account several effects related to the noise generation mechanism, a 3D numerical aeroacoustic model of the pantograph was needed. Specifically, the theoretical background adopted is the Williams and Hawkings acoustic analogy, an evolution of the well-known Lighthill acoustic analogy. The latter consists in the substitution of the noise generating surface with a distribution of dipole punctual sound sources, whose intensity is proportional to the temporal variation of fluid dynamic quantities acting in that point. As a result, a more detailed characterization of the noise spectrum can be provided. The analytical and numerical results have been then compared in terms of sound pressure levels and a well spectral contents, to themselves and to available experimental data

Should Minor League Mean Minor Pay: A Student Analysis of the Public Debate

Historically, and at the time of this study’s project, many minor league baseball players in the United States were paid below the federal minimum wage, which has been recently circulating in the media and has been a source of ongoing controversy (McDaniel, 2022). This article is a write-up to the first author’s end-of-term course project, which was supervised by the second author. The objective of the present study was to perform a historical and philosophical analysis of the public debate on minor league pay as well as describe ethical arguments within the debate. This should guide future debates on labor rights and fairness within sport, including professional leagues. Methods for a single-artifact descriptive case study (March 2021) were used to describe opposing views on the issue of minor league pay in baseball, which were then analyzed using historical and philosophical perspectives. The case study material was a 2019 popular press article of journalism covering both sides of the debate. Two modes of qualitative research were used: qualitative critical analysis and discourse analysis. Qualitative critical analysis entailed comparing discourse within the case article to information within one peer-reviewed research article, which presented historical and jurisprudence discourse and research on why Major League Baseball team-owners have been allowed to legally pay minor league players below the federal minimum wage cut-point. Fourteen parsimonious concepts from one undergraduate course on physical activity perspectives were used to describe and analyze data extracted vis-à-vis the qualitative critical analysis, followed by a discourse analysis of the extracted data. We discuss the study results, then present recommendations for future research. We conclude with a reflection from the first author about her project experience

Evolution of the Mass-Metallicity relations in passive and star-forming galaxies from SPH-cosmological simulations

We present results from SPH-cosmological simulations, including self-consistent modelling of SN feedback and chemical evolution, of galaxies belonging to two clusters and twelve groups. We reproduce the mass-metallicity (ZM) relation of galaxies classified in two samples according to their star-forming activity, as parametrized by their sSFR, across a redshift range up to z=2. Its slope shows irrelevant evolution in the passive sample, being steeper in groups than in clusters. However, the sub-sample of high-mass passive galaxies only is characterized by a steep increase of the slope with redshift, from which it can be inferred that the bulk of the slope evolution of the ZM relation is driven by the more massive passive objects. (...ABRIDGED...) The ZM relation for the star-forming sample reveals an increasing scatter with redshift, indicating that it is still being built at early epochs. The star-forming galaxies make up a tight sequence in the SFR-M_* plane at high redshift, whose scatter increases with time alongside with the consolidation of the passive sequence. We also confirm the anti-correlation between sSFR and stellar mass, pointing at a key role of the former in determining the galaxy downsizing, as the most significant means of diagnostics of the star formation efficiency. Likewise, an anti-correlation between sSFR and metallicity can be established for the star-forming galaxies, while on the contrary more active galaxies in terms of simple SFR are also metal-richer. We discuss these results in terms of the mechanisms driving the evolution within the high- and low-mass regimes at different epochs: mergers, feedback-driven outflows and the intrinsic variation of the star formation efficiency.Comment: Emended list of author

Issues in the Treatment of Depressed Children

Basic research into the cognitive, behavioral, familial, and physiological disturbances associated with depressive disorders during childhood is reviewed. hnplications for the development of a treatment program are discussed and a comprehensive treatment model is proposed. The proposed model includes intervention strategies for the child, parents, family, and school. The child component consists of intervention strategies for the affective, cognitive, behavioral, and physiological disturbances that are evident from the existing research. The parent training component is designed to address disturbances in parenting due to cognitive disturbances and skills deficits. The family therapy component emphasizes changing interaction patterns that communicate schema-consistent maladaptive interactions. A school consultation component is proposed in which school personnel support the skills training through prompting use of the skills and reinforcement of the use of the coping skills