998 resultados para sound archives


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The population of eastern oyster, C. virginica, has declined over the last century on most areas of the east and gulf coasts. North Carolina’s restoration efforts depend on the construction of subtidal oyster reefs to be used as broodstock sanctuaries in Pamlico Sound, NC. Successful restoration of the oyster population requires several thriving reefs connected as a meta-population. C. virginica has a 2-3 week larval stage, during which it gradually settles through the water column. Larvae that can travel from one reef to another during that stage form the basis of a meta-population. (PDF contains 3 pages)

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The goal of the Puget Sound Nearshore Ecosystem Restoration Project (PSNERP) is to improve system-wide functionality of nearshorei ecosystem processes. To achieve that goal, PSNERP plans to strategically restore nearshore sites throughout Puget Sound. PSNERP scientists are assessing changes to the nearshore, and will recommend an environmentally strategic restoration portfolio. Yet, PSNERP also needs stakeholder input to design a socially strategic portfolio. This research investigates the values and preferences of stakeholders in the Whidbey Sub-Basin of Puget Sound to help PSNERP be both socially and environmentally strategic. This investigation may be repeated in the six other Puget Sound Sub-Basins. The results will guide restoration portfolio design and future stakeholder involvement activities. This study examines four areas of stakeholder values and preferences: 1) beliefs about the causes, solutions, and severity of nearshore problems; 2) priorities for nearshore features, shoreforms, developments, and restoration objectives; 3) thoughts about ecosystem servicesiii and trade-offs among them; and 4) visions of a future, restored Puget Sound nearshore and the role of science in attaining this vision. The study is framed by two hypotheses from the Advocacy Coalition Framework (ACF), which suggests that groups of policy advocates form around shared “policy core beliefs” which can transcend traditional categories of stakeholders.(PDF contains 3 pages)

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Ultralow-velocity zones (ULVZs) are small structures at the base of the mantle characterized by sound velocities up to 30% lower than those of surrounding mantle. In this thesis, we propose that iron-rich (Mg,Fe)O plays a key role in the observed sound velocities, and argue that chemically distinct, iron-enriched structures are consistent with both the low sound velocities and the measured shapes of ULVZs.

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The problem is to calculate the attenuation of plane sound waves passing through a viscous, heat-conducting fluid containing small spherical inhomogeneities. The attenuation is calculated by evaluating the rate of increase of entropy caused by two irreversible processes: (1) the mechanical work done by the viscous stresses in the presence of velocity gradients, and (2) the flow of heat down the thermal gradients. The method is first applied to a homogeneous fluid with no spheres and shown to give the classical Stokes-Kirchhoff expressions. The method is then used to calculate the additional viscous and thermal attenuation when small spheres are present. The viscous attenuation agrees with Epstein's result obtained in 1941 for a non-heat-conducting fluid. The thermal attenuation is found to be similar in form to the viscous attenuation and, for gases, of comparable magnitude. The general results are applied to the case of water drops in air and air bubbles in water.

For water drops in air the viscous and thermal attenuations are camparable; the thermal losses occur almost entirely in the air, the thermal dissipation in the water being negligible. The theoretical values are compared with Knudsen's experimental data for fogs and found to agree in order of magnitude and dependence on frequency. For air bubbles in water the viscous losses are negligible and the calculated attenuation is almost completely due to thermal losses occurring in the air inside the bubbles, the thermal dissipation in the water being relatively small. (These results apply only to non-resonant bubbles whose radius changes but slightly during the acoustic cycle.)

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Otto Kelland was a truly unique individual in Newfoundland. During his long life he had several careers from being a prison superintendant to being an instructor at Marine Institute. During his life Kelland made hundreds of wooden boat models. They are beautifuly hand-crafted and represented the type of watercraft used by fishermen in Newfoundland. The collection of boat models made by Otto Kelland and owned by Marine Institute made an ideal object to be digitalized. In particular the collection of dories was an ideal group to be digitized. They were housed in one cabinet and accompanied by hand-written documents describing each model. The Digital Archives Initiative (DAI) is a “gateway to the learning and research-based cultural resources held by Memorial University of Newfoundland and partnering organizations.” The DAI hosts a variety of collections which together reinforce the importance, past and present, of Newfoundland and Labrador's history and culture. I will give an oral presentation of the project followed by a demonstration of the Otto Kelland Dories exhibit on the Digital Archives Initiative (DAI) at Memorial University of Newfoundland. I will be happy to answer questions following my presentation.

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I. The attenuation of sound due to particles suspended in a gas was first calculated by Sewell and later by Epstein in their classical works on the propagation of sound in a two-phase medium. In their work, and in more recent works which include calculations of sound dispersion, the calculations were made for systems in which there was no mass transfer between the two phases. In the present work, mass transfer between phases is included in the calculations.

The attenuation and dispersion of sound in a two-phase condensing medium are calculated as functions of frequency. The medium in which the sound propagates consists of a gaseous phase, a mixture of inert gas and condensable vapor, which contains condensable liquid droplets. The droplets, which interact with the gaseous phase through the interchange of momentum, energy, and mass (through evaporation and condensation), are treated from the continuum viewpoint. Limiting cases, for flow either frozen or in equilibrium with respect to the various exchange processes, help demonstrate the effects of mass transfer between phases. Included in the calculation is the effect of thermal relaxation within droplets. Pressure relaxation between the two phases is examined, but is not included as a contributing factor because it is of interest only at much higher frequencies than the other relaxation processes. The results for a system typical of sodium droplets in sodium vapor are compared to calculations in which there is no mass exchange between phases. It is found that the maximum attenuation is about 25 per cent greater and occurs at about one-half the frequency for the case which includes mass transfer, and that the dispersion at low frequencies is about 35 per cent greater. Results for different values of latent heat are compared.

II. In the flow of a gas-particle mixture through a nozzle, a normal shock may exist in the diverging section of the nozzle. In Marble’s calculation for a shock in a constant area duct, the shock was described as a usual gas-dynamic shock followed by a relaxation zone in which the gas and particles return to equilibrium. The thickness of this zone, which is the total shock thickness in the gas-particle mixture, is of the order of the relaxation distance for a particle in the gas. In a nozzle, the area may change significantly over this relaxation zone so that the solution for a constant area duct is no longer adequate to describe the flow. In the present work, an asymptotic solution, which accounts for the area change, is obtained for the flow of a gas-particle mixture downstream of the shock in a nozzle, under the assumption of small slip between the particles and gas. This amounts to the assumption that the shock thickness is small compared with the length of the nozzle. The shock solution, valid in the region near the shock, is matched to the well known small-slip solution, which is valid in the flow downstream of the shock, to obtain a composite solution valid for the entire flow region. The solution is applied to a conical nozzle. A discussion of methods of finding the location of a shock in a nozzle is included.

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Após o sucesso de vendas do Viagra, medicamento indicado para o tratamento da disfunção erétil, lançado em 1998, houve uma rápida proliferação de artigos, livros e encontros sobre as disfunções sexuais femininas. Desde 2000, um intenso debate sobre o envolvimento da indústria farmacêutica na produção biomédica sobre as disfunções sexuais femininas e a concomitante busca por um medicamento similar ao Viagra destinado às mulheres tem envolvido profissionais de diferentes disciplinas. Esta dissertação teve como objetivo investigar os discursos científicos sobre as disfunções sexuais femininas, através do exame dos artigos publicados no periódico Archives of Sexual Behavior, desde sua fundação, em 1971, até 2007. O periódico foi escolhido por sua legitimidade neste campo de saberes, por abranger um amplo período (36 anos) e seu caráter multidisciplinar. Pretendeu-se investigar quando, como e por quais grupos profissionais as disfunções sexuais femininas foram descritas e abordadas no periódico. No caso das chamadas disfunções sexuais, as descrições científicas, que vêm aumentando significativamente nos últimos anos, dão origem a prescrições de terapias, medicamentos, intervenções cirúrgicas, programas de educação sexual e políticas públicas. Ou seja, subjacente a esse discurso, que afirma ser empírico e imparcial, estão processos que se encontram muito além dos limites de um laboratório ou das atividades de um pesquisador. Buscou-se, assim, pensar a produção científica como produto de articulações e negociações que se desenrolam em esferas diversas, envolvendo processos culturais, sociais, econômicos e também cognitivos ou científicos, em contraposição às concepções que caracterizam a ciência como um projeto que apenas revela verdades. Para tanto, foi apresentado o contexto do surgimento de uma ciência da sexualidade, no decorrer do século XIX e, em seguida, o contexto no qual emergiram os discursos sobre as disfunções sexuais femininas, o que propiciou sua emergência naquele dado momento, o modo como foram definidas e por quem, como se articularam a processos sociais, econômicos e culturais e que transformações sofreram ao longo dos anos.

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Acoustic recorders were used to document black drum (Pogonias cromis) sound production during their spawning season in southwest Florida. Diel patterns of sound production were similar to those of other sciaenid fishes and demonstrated increased sound levels from the late afternoon to early evening—a period that lasted up to 12 hours during peak season. Peak sound production occurred from January through March when water temperatures were between 18° and 22°C. Seasonal trends in sound production matched patterns of black drum reproductive readiness and spawning reported previously for populations in the Gulf of Mexico. Total acoustic energy of nightly chorus events was estimated by integration of the sound pressure amplitude with duration above a threshold based on daytime background levels. Maximum chorus sound level was highly correlated with total acoustic energy and was used to quantitatively represent nightly black drum sound production. This study gives evidence that long-term passive acoustic recordings can provide information on the timing and location of black drum reproductive behavior that is similar to that provided by traditional, more costly methods. The methods and results have broad application for the study of many other fish species, including commercially and recreationally valuable reef fishes that produce sound in association with reproductive behav

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Fjord estuaries are common along the northeast Pacific coastline, but little information is available on fish assemblage structure and its spatiotemporal variability. Here, we examined changes in diversity metrics, species biomasses, and biomass spectra (the distribution of biomass across body size classes) over three seasons (fall, winter, summer) and at multiple depths (20 to 160 m) in Puget Sound, Washington, a deep and highly urbanized fjord estuary on the U.S. west coast. Our results indicate that this fish assemblage is dominated by cartilaginous species (spotted ratfish [Hydrolagus colliei] and spiny dogfish [Squalus acanthias]) and therefore differs fundamentally from fish assemblages found in shallower estuaries in the northeast Pacific. Diversity was greatest in shallow waters (<40 m), where the assemblage was composed primarily of flatfishes and sculpins, and lowest in deep waters (>80 m) that are more common in Puget Sound and that are dominated by spotted ratf ish and seasonally (fall and summer) by spiny dogfish. Strong depth-dependent variation in the demersal fish assemblage may be a general feature of deep fjord estuaries and indicates pronounced spatial variability in the food web. Future comparisons with less impacted fjords may offer insight into whether cartilaginous species naturally dominate these systems or only do so under conditions related to human-caused ecosystem degradation. Information on species distributions is critical for marine spatial planning and for modeling energy flows in coastal food webs. The data presented here will aid these endeavors and highlight areas for future research in this important yet understudied system.