Coherence Extrapolation for Underwater Ambient Noise

This paper considers extrapolation of the vertical coherence of surface-generated oceanic ambient noise to simulate measurements made on a longer sensor array. The extrapolation method consists of projecting the noise coherence measured with a limited aperture array into the domain spanned by prolate spheroidal wave functions, which are an orthogonal basis defined by array parameters and the noise frequency. Using simulated data corresponding to selected multi-layered seabeds as ground truth, the performance of the extrapolation method is explored. Application of the technique is also demonstrated on experimental data

Variable Intrinsic Absorption in Mrk 279

We examine the variability in the intrinsic absorption in the Seyfert 1 galaxy Mrk 279 using three epochs of observations from the Far Ultraviolet Spectroscopic Explorer (FUSE) and two epochs of observations with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. Rather than finding simple photoionization responses of the absorbing gas to changes in the underlying continuum, the observed changes in the absorption profiles can be understood more clearly if the effective covering fraction of the gas in all emission components, continuum and broad and intermediate velocity width emission lines, is accounted for. While we do not uniquely solve for all of these separate covering fractions and the ionic column densities using the spectral data, we examine the parameter space using previously well-constrained solutions for continuum and single emission component covering fractions. Assuming full coverage of the continuum, we find that of the two velocity components of the Mrk 279 absorption most likely associated with its outflow, one likely has zero coverage of the intermediate line region while the other does not. For each component, however, the broad line region is more fully covered than the intermediate line region. Changes in the O VI column densities are unconstrained due to saturation, but we show that small changes in the nonsaturated C IV and N V column densities are consistent with the outflow gas having zero or partial covering of the intermediate line region and an ionization parameter changing from ~0.01 to ~0.1 from 2002 to 2003 as the UV continuum flux increased by a factor of ~8. The absence of a change in the C III absorbing column density is attributed to this species arising outside the Mrk 279 outflow.Comment: 36 pages, 18 figures, accepted to Ap

The disconnect between knowledge and perceptions: A study of fishermen’s local ecological knowledge and their perception of the state of fisheries and how these are managed in the Dominican Republic

Understanding what fishers know about the ecology of the fish they catch, and how they perceive the state and management of their fisheries can guide efforts towards more sustainable fishing practices. We tested relationships between fishers’ local ecological knowledge (LEK) and their perceptions of their fisheries and of marine protected areas in the Dominican Republic. A qualitative-quantitative methodological sequence using data from interviews with 152 multi-species fishers revealed variable, but generally high levels of LEK, particularly of habitat use and predator–prey interactions. The majority reported negative perceptions of the state of their fishery and were aware of local management actions. Contrary to study expectations, we found that fishers’ LEK, measured by Cultural Consensus Analysis, did not significantly co-vary with their perceptions of the state of fisheries or with their awareness of, and support for, marine protected areas. These results highlight the need to identify and understand barriers to information flow and communication in local fisheries’ social/political networks

An Eigenvector-Based Test for Local Stationarity Applied to Array Processing

In sonar array processing, a challenging problem is the estimation of the data covariance matrix in the presence of moving targets in the water column, since the time interval of data local stationarity is limited. This work describes an eigenvector-based method for proper data segmentation into intervals that exhibit local stationarity, providing data-driven higher bounds for the number of snapshots available for computation of time-varying sample covariance matrices. Application of the test is illustrated with simulated data in a horizontal array for the detection of a quiet source in the presence of a loud interferer

The N=1 superstring as a topological field theory

By "untwisting" the construction of Berkovits and Vafa, one can see that the N=1 superstring contains a topological twisted N=2 algebra, with central charge c^ = 2. We discuss to what extent the superstring is actually a topological theory.Comment: 8 Pages (LaTeX). TAUP-2155-9

Trans-Dimensional Geoacoustic Inversion of Wind-Driven Ambient Noise

This letter applies trans-dimensional Bayesian geoacoustic inversion to quantify the uncertainty due to model selection when inverting bottom-loss data derived from wind-driven ambient-noise measurements. A partition model is used to represent the seabed, in which the number of layers, their thicknesses, and acoustic parameters are unknowns to be determined from the data. Exploration of the parameter space is implemented using the Metropolis–Hastings algorithm with parallel tempering, whereas jumps between parameterizations are controlled by a reversible-jump Markov chain Monte Carlo algorithm. Sediment uncertainty profiles from inversion of simulated and experimental data are presented

Prioritized crop wild relatives in Spain: status on the National Inventory of Plant Genetic Resources for Agriculture and Food

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Gira técnica a Embrapa Algodao, área de la empresa Brasilera de investigación Agropecuaria Embrapa.

En la reunión anual de Coordinadores regionales de Transferencia de Tecnología del Plan Algodón realizada en Rionegro (Antioquia) el 14-15 de Septiembre del 2000, el 1.A. Tomás Norato F .. Regional 6, presentó como uno es1Tategia práctica de capacitación, la propuesta de realizar visitas técnicas en grupo o países con zonas destacadas en la producción algodonero, para observar y acopiar información sobre los procesos de entrega de tecnologías con el fin de efectuar posibles mejoras a lo actividad de transferencia tecnológico del Pion Algodón en nuestro país. En esa oportunidad se refirió a la posibilidad de visitar Brasil, productor relevante de algodón en América Latina.Algodón-Gossypium herbaceu