Long-Term, Seasonal, and Event-Driven Sediment Movement on East Beach, San Salvador Island, Bahamas

East Beach is a modern, medium-energy shoreline located on the northeast coast of San Salvador Island, Bahamas. Stake and horizon profiles were made at 9 sites along a 1-km section of the beach in June, 1990, and every six months thereafter through January,1992. These observations appear to confirm that East Beach is a prograding shoreline, building onto the eastern shelf of the island. Seasonally corrected volume calculations indicate that between June, 1990 and January, 1992 approximately 14,000 m3 of new sand per kilometer were added to the East Beach system, with most of the sand likely derived from the nearshore shelf area. Visual evidence for progradation could be seen in the formation of a heavily vegetated berm along the backshore, that by June, 1991 had reached a maximum height of 40 cm before its destruction by the powerful storm that hit San Salvador in late October, 1991. Seasonal topographic measurements and volume calculations indicate a minimum of 8,600 m3/km of sediment moving offshore in response to higher average wave energies in the winter, and returning to build a wide foreshore and pronounced berm during the summer months. The late October storm battered East Beach with waves that entrained meter-sized blocks of coral, cut back the primary dune line by an average of 5.1 m, and washed over approximately 1,500 m3of sediment into the primary dune swale. Storm damage was measurably less severe at northern stations, possibly because of sheltering by Northeast Point and Man Head Cay, or by baffling action of the dense patch reefs offshore, or both

Neurophysiology

Contains reports on five research projects.National Institutes of Health (Training Grant 5 TO1 EY00090)Bell Laboratories (Grant

Gravitational wave detectors based on matter wave interferometers (MIGO) are no better than laser interferometers (LIGO)

We show that a recent claim that matter wave interferometers have a much higher sensitivity than laser interferometers for a comparable physical setup is unfounded. We point out where the mistake in the earlier analysis is made. We also disprove the claim that only a description based on the geodesic deviation equation can produce the correct physical result. The equations for the quantum dynamics of non-relativistic massive particles in a linearly perturbed spacetime derived here are useful for treating a wider class of related physical problems. A general discussion on the use of atom interferometers for the detection of gravitational waves is also provided.Comment: 16 pages, REVTeX4; minor changes, one figure and a few references were added, an additional appendix was included where we explain why, contrary to the claims in gr-qc/0409099, the effects due to the reflection off the mirrors cancel out in the final result for the phase shif

Risky Sex and HIV Acquisition Among HIV Serodiscordant Couples in Zambia, 2002-2012: What Does Alcohol Have To Do With It?

In this paper we evaluate the effects of heavy alcohol consumption on sexual behavior, HIV acquisition, and antiretroviral treatment (ART) initiation in a longitudinal open cohort of 1929 serodiscordant couples in Lusaka, Zambia from 2002 to 2012. We evaluated factors associated with baseline heavy alcohol consumption and its association with condomless sex with the study partner, sex outside of the partnership, and ART initiation using multivariable logistic regression. We estimated the effect of alcohol consumption on HIV acquisition using multivariable Cox models. Baseline factors significantly associated with women's heavy drinking (drunk weekly or more in 12-months before enrollment) included woman's older age (adjusted prevalence odds ratio [aPOR] = 1.04), partner heavy drinking (aPOR = 3.93), and being HIV-infected (aPOR = 2.03). Heavy drinking among men was associated with less age disparity with partner (aPOR per year disparity = 0.97) and partner heavy drinking (aPOR = 1.63). Men's being drunk daily (aOR = 1.18), women's being drunk less than monthly (aOR = 1.39) vs. never drunk and being in a male HIV-negative and female HIV-positive union (aOR = 1.45) were associated with condomless sex. Heavy alcohol use was associated with having 1 or more outside sex partners among men (aOR drunk daily = 1.91, drunk weekly = 1.32, drunk monthly = 2.03 vs. never), and women (aOR drunk monthly = 2.75 vs. never). Being drunk weekly or more increased men's risk of HIV acquisition (adjusted hazard ratio [aHR] = 1.72). Men and women being drunk weekly or more was associated (p < 0.1) with women's seroconversion (aHR = 1.42 and aHR = 3.71 respectively). HIV-positive women who were drunk monthly or more had lower odds of initiating ART (aOR = 0.83; 95% CI = 0.70-0.99) adjusting for age, months since baseline and previous pregnancies. Individuals in HIV-serodiscordant couples who reported heavy drinking had more outside sex partnerships and condomless sex with their study partner and were more likely to acquire HIV. HIV-positive women had lower odds of initiating ART if they were heavy drinkers

Dynamics of Scalar Fields in the Background of Rotating Black Holes

A numerical study of the evolution of a massless scalar field in the background of rotating black holes is presented. First, solutions to the wave equation are obtained for slowly rotating black holes. In this approximation, the background geometry is treated as a perturbed Schwarzschild spacetime with the angular momentum per unit mass playing the role of a perturbative parameter. To first order in the angular momentum of the black hole, the scalar wave equation yields two coupled one-dimensional evolution equations for a function representing the scalar field in the Schwarzschild background and a second field that accounts for the rotation. Solutions to the wave equation are also obtained for rapidly rotating black holes. In this case, the wave equation does not admit complete separation of variables and yields a two-dimensional evolution equation. The study shows that, for rotating black holes, the late time dynamics of a massless scalar field exhibit the same power-law behavior as in the case of a Schwarzschild background independently of the angular momentum of the black hole.Comment: 14 pages, RevTex, 6 Figure

2017-2018 The Fulfillment of a Dream

Featuring Roberta Rust, David Cole and the students of the Piano and String Programs.https://spiral.lynn.edu/foc-events/1025/thumbnail.jp

Neurophysiology

Contains research objectives and summary of research.National Institutes of Health (Grant 1 RO1 EY01149-01)National Institutes of Health (Grant 5 P01 GM14940-07)Bell Telephone Laboratories, Inc. (Grant)National Institutes of Health (Grant 5 TO1 GM01555-07)M. I. T. Sloan Fund for Basic Researc

Neurophysiology

Contains research objectives and summary of research on ten research projects.National Institutes of Health (Grant 5 R01 EY01149-02)National Institutes of Health (Grant 1 T01 EY00090-01)Bell Telephone Laboratories, Inc. (Grant)National Institutes of Health (Grant 5 TO1 GM00778-19)National Institutes of Health (Grant 5 TO1 GM01555-08

The imposition of Cauchy data to the Teukolsky equation II: Numerical comparison with the Zerilli-Moncrief approach to black hole perturbations

We revisit the question of the imposition of initial data representing astrophysical gravitational perturbations of black holes. We study their dynamics for the case of nonrotating black holes by numerically evolving the Teukolsky equation in the time domain. In order to express the Teukolsky function Psi explicitly in terms of hypersurface quantities, we relate it to the Moncrief waveform phi_M through a Chandrasekhar transformation in the case of a nonrotating black hole. This relation between Psi and phi_M holds for any constant time hypersurface and allows us to compare the computation of the evolution of Schwarzschild perturbations by the Teukolsky and by the Zerilli and Regge-Wheeler equations. We explicitly perform this comparison for the Misner initial data in the close limit approach. We evolve numerically both, the Teukolsky (with the recent code of Ref. [1]) and the Zerilli equations, finding complete agreement in resulting waveforms within numerical error. The consistency of these results further supports the correctness of the numerical code for evolving the Teukolsky equation as well as the analytic expressions for Psi in terms only of the three-metric and the extrinsic curvature.Comment: 14 pages, 7 Postscript figures, to appear in Phys. Rev.