Fertilization in Broadcast-Spawning Corals of the Flower Garden Banks National Marine Sanctuary

Broadcast spawning is considered to be the dominant reproductive strategy for reef corals, but little is known about two critical postspawning processes, fertilization and early larval development. Instead, most efforts have focused on dispersal and recruitment. Since 1993, we have examined coral fertilization and development at the Flower Garden Banks, which contain two isolated reefs with predictable and dramatic annual mass spawning events in the northwestern Gulf of Mexico. Observations of in vitro fertilization indicate that the hermaphroditic scleractinian species Colpophyllia natans, Diploria strigosa, Monfastraea faveolata, and M. franksi all have high fertilization potentials when outcrossing. However, although D. strigosa can self-fertilize readily, self-fertilization levels within C. natans and the Montastraea species are low. In addition, interspecific crossing attempts among the hermaphroditic species of Montastraea (M. franksi, M. faveolata, and M. annularis) yielded low levels of fertilization. The differences observed in the timing of spawning and the low hybridization success between the Montastraea siblings lend additional support to their recent reclassification as separate species. Spawned egg samples collected immediately upon release from female colonies of the gonochoric species M. cavernosa and Stephanocoenia intersepta produced an unexpected observation—very high levels of fertilization. This suggests internal fertilization prior to egg release, a process that has not heretofore been observed in a broadcast-spawning scleractinian

Bi-partite mode entanglement of bosonic condensates on tunneling graph

We study a set of $L$ spatial bosonic modes localized on a graph $\Gamma.$ The particles are allowed to tunnel from vertex to vertex by hopping along the edges of $\Gamma.$ We analyze how, in the exact many-body eigenstates of the system i.e., Bose-Einstein condensates over single-particle eigenfunctions, the bi-partite quantum entanglement of a lattice vertex with respect to the rest of the graph depends on the topology of $\Gamma.$Comment: 3 Pages LaTeX, 2 Figures include

Speckle-visibility spectroscopy: A tool to study time-varying dynamics

We describe a multispeckle dynamic light scattering technique capable of resolving the motion of scattering sites in cases that this motion changes systematically with time. The method is based on the visibility of the speckle pattern formed by the scattered light as detected by a single exposure of a digital camera. Whereas previous multispeckle methods rely on correlations between images, here the connection with scattering site dynamics is made more simply in terms of the variance of intensity among the pixels of the camera for the specified exposure duration. The essence is that the speckle pattern is more visible, i.e. the variance of detected intensity levels is greater, when the dynamics of the scattering site motion is slow compared to the exposure time of the camera. The theory for analyzing the moments of the spatial intensity distribution in terms of the electric field autocorrelation is presented. It is demonstrated for two well-understood samples, a colloidal suspension of Brownian particles and a coarsening foam, where the dynamics can be treated as stationary. However, the method is particularly appropriate for samples in which the dynamics vary with time, either slowly or rapidly, limited only by the exposure time fidelity of the camera. Potential applications range from soft-glassy materials, to granular avalanches, to flowmetry of living tissue.Comment: review - theory and experimen

Minimum Wage Channels of Adjustment

Industrial Relations, forthcoming Abstract: The effects of minimum wage increases in 2007-2009 are analyzed using a sample of restaurants from Georgia/Alabama. Store-level payroll records provide precise measures of compliance costs. Examined are multiple adjustment channels. Exploiting variation in compliance costs across restaurants, we find employment and hours responses to be variable and in most cases statistically insignificant. Channels of adjustment to wage increases and to changes in non-labor costs include prices, profits, wage compression, turnover, and performance standards

GenASiS: General Astrophysical Simulation System. I. Refinable Mesh and Nonrelativistic Hydrodynamics

GenASiS (General Astrophysical Simulation System) is a new code being developed initially and primarily, though by no means exclusively, for the simulation of core-collapse supernovae on the world's leading capability supercomputers. This paper---the first in a series---demonstrates a centrally refined coordinate patch suitable for gravitational collapse and documents methods for compressible nonrelativistic hydrodynamics. We benchmark the hydrodynamics capabilities of GenASiS against many standard test problems; the results illustrate the basic competence of our implementation, demonstrate the strengths and limitations of the HLLC relative to the HLL Riemann solver in a number of interesting cases, and provide preliminary indications of the code's ability to scale and to function with cell-by-cell fixed-mesh refinement.Comment: Belated update to version accepted ApJ

Resourcing resilience: Social protection for HIV prevention amongst children and adolescents in Eastern and Southern Africa

Adolescents are the only age group with growing AIDS-related morbidity and mortality in Eastern and Southern Africa, making HIV prevention research among this population an urgent priority. Structural deprivations are key drivers of adolescent HIV infection in this region. Biomedical interventions must be combined with behavioural and social interventions to alleviate the socio-structural determinants of HIV infection. There is growing evidence that social protection has the potential to reduce the risk of HIV infection among children and adolescents. This research combined expert consultations with a rigorous review of academic and policy literature on the effectiveness of social protection for HIV prevention among children and adolescents, including prevention for those already HIV-positive. The study had three goals: (i) assess the evidence on the effectiveness of social protection for HIV prevention, (ii) consider key challenges to implementing social protection programmes that promote HIV prevention, and (iii) identify critical research gaps in social protection and HIV prevention, in Eastern and Southern Africa. Causal pathways of inequality, poverty, gender and HIV risk require flexible and responsive social protection mechanisms. Results confirmed that HIV-inclusive child- and adolescent-sensitive social protection has the potential to interrupt risk pathways to HIV infection and foster resilience. In particular, empirical evidence (literature and expert feedback) detailed the effectiveness of combination social protection particularly cash/in-kind components combined with “care” and “capability” among children and adolescents. Social protection programmes should be dynamic and flexible, and consider age, gender, HIV-related stigma, and context, including cultural norms, which offer opportunities to improve programmatic coverage, reach and uptake. Effective HIV prevention also requires integrated social protection policies, developed through strong national government ownership and leadership. Future research should explore which combinations of social protection work for sub-groups of children and adolescents, particularly those living with HIV