1,652 research outputs found
Broadscale coral disease interventions elicit efficiencies in endemic disease response
The presence and abundance of reef-building corals are crucial to the long-term existence of Caribbean coral reef ecosystems, providing both direct and indirect, local and global, ecological, economic, and social benefits. In 2014, stony coral tissue loss disease (SCTLD) was first identified in southeast Florida and remains endemic to the region, while continuing to spread throughout the Caribbean. Effective in situ intervention treatments using antibiotic paste can halt lesion progression on Montastraea cavernosa up to 90% of the time. This study investigated intervention activities over a three-year period to identify efficiencies in disease response. Since May 2019, 1,037 corals, \u3e85% of which were M. cavernosa, were treated during disease intervention dives in southeast Florida. Treated coral density, the number of treated corals per meter along a dive track, was significantly higher in the first year compared to subsequent years and displayed annual peaks in late summer each year. Season significantly influenced treatment density, leading to higher values in the wet season across all years, 2019 to 2022. Areas of highest treatment density were identified between Haulover Inlet and Government Cut near Miami and Hillsboro Inlet in northern Broward County. Areas with the highest treatment density were only identified in the first year, suggesting that broadscale interventions may have decreased disease prevalence in subsequent years. Results indicate that in endemic areas with sporadic and dynamic disease prevalence, intervention efforts should be weighted proportionally across space and time to maximize intervention efficiency. This study provides optimistic results for the potential of interventions reducing disease prevalence and supports that disease interventions are an effective coral restoration tool that can decrease the increasing burden on post hoc coral restoration
Enhanced He-alpha emission from "smoked" Ti targets irradiated with 400nm, 45 fs laser pulses
We present a study of He-like 1s(2)-1s2p line emission from solid and low-density Ti targets under similar or equal to 45 fs laser pulse irradiation with a frequency doubled Ti: Sapphire laser. By varying the beam spot, the intensity on target was varied from 10(15) W/cm(2) to 10(19) W/cm(2). At best focus, low density "smoked" Ti targets yield similar to 20 times more He-alpha than the foil targets when irradiated at an angle of 45 degrees with s-polarized pulses. The duration of He-alpha emission from smoked targets, measured with a fast streak camera, was similar to that from Ti foils
The simulation of the activity dependent neural network growth
It is currently accepted that cortical maps are dynamic constructions that
are altered in response to external input. Experience-dependent structural
changes in cortical microcurcuts lead to changes of activity, i.e. to changes
in information encoded. Specific patterns of external stimulation can lead to
creation of new synaptic connections between neurons. The calcium influxes
controlled by neuronal activity regulate the processes of neurotrophic factors
released by neurons, growth cones movement and synapse differentiation in
developing neural systems. We propose a model for description and investigation
of the activity dependent development of neural networks. The dynamics of the
network parameters (activity, diffusion of axon guidance chemicals, growth cone
position) is described by a closed set of differential equations. The model
presented here describes the development of neural networks under the
assumption of activity dependent axon guidance molecules. Numerical simulation
shows that morpholess neurons compromise the development of cortical
connectivity.Comment: 10 pages, 2 figure
Combination Forecasts of Bond and Stock Returns: An Asset Allocation Perspective
We investigate the out-of-sample forecasting ability of the HML, SMB, momentum, short-term and long-term reversal factors along with their size and value decompositions on U.S. bond and stock returns for a variety of horizons ranging from the short run (1 month) to the long run (2 years). Our findings suggest that these factors contain significantly more information for future bond and stock market returns than the typically employed financial variables. Combination of forecasts of the empirical factors turns out to be particularly successful, especially from an an asset allocation perspective. Similar findings pertain to the European and Japanese markets
Health representations, perceived valence, and concept associations for symbols as food cues: A mixed-methods approach
Researchers have experimented with a range of point-of-purchase (PoP) interventions in supermarkets, restaurants, and cafeterias. In general, these interventions have employed written materials. This research tested symbols to visually summarize information about the (un)healthiness of food. Study one explored health representations and valence associated with the image of a heart, a bathroom scale, and a running shoe using qualitative field interviews (NÂ =Â 1200). Study two explored accessibility of a priori concept associations for two of those images, stratified by valence, in a computerized response latency task (NÂ =Â 40). Study one indicted that the heart was best linked to its intended theme "heart health." Concerning valence, the heart was seen as both positive and negative whereas the scale was less likely to be viewed as positive relative to the running shoe. In study two, the heart was linked to five of the six a priori concepts and there was evidence that three of these were more accessible. Overall, the heart was better linked to positive poles than negative ones. A heart symbol may be useful to prompt heart healthy choices at the PoP. There was evidence that a scale may bias choice away from undesirable foods
Theory of laser ion acceleration from a foil target of nanometers
A theory for laser ion acceleration is presented to evaluate the maximum ion
energy in the interaction of ultrahigh contrast (UHC) intense laser with a
nanometer-scale foil. In this regime the energy of ions may be directly related
to the laser intensity and subsequent electron dynamics. This leads to a simple
analytical expression for the ion energy gain under the laser irradiation of
thin targets. Significantly, higher energies for thin targets than for thicker
targets are predicted. Theory is concretized to the details of recent
experiments which may find its way to compare with these results.Comment: 22 pages 7 figures. will be submitted to NJ
Superfluid behaviour of a two-dimensional Bose gas
Two-dimensional (2D) systems play a special role in many-body physics.
Because of thermal fluctuations, they cannot undergo a conventional phase
transition associated to the breaking of a continuous symmetry. Nevertheless
they may exhibit a phase transition to a state with quasi-long range order via
the Berezinskii-Kosterlitz-Thouless (BKT) mechanism. A paradigm example is the
2D Bose fluid, such as a liquid helium film, which cannot Bose-condense at
non-zero temperature although it becomes superfluid above a critical phase
space density. Ultracold atomic gases constitute versatile systems in which the
2D quasi-long range coherence and the microscopic nature of the BKT transition
were recently explored. However, a direct observation of superfluidity in terms
of frictionless flow is still missing for these systems. Here we probe the
superfluidity of a 2D trapped Bose gas with a moving obstacle formed by a
micron-sized laser beam. We find a dramatic variation of the response of the
fluid, depending on its degree of degeneracy at the obstacle location. In
particular we do not observe any significant heating in the central, highly
degenerate region if the velocity of the obstacle is below a critical value.Comment: 5 pages, 3 figure
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Kinematics of femtosecond laser-generated plasma expansion: Determination of sub-micron density gradient and collisionality evolution of over-critical laser plasmas
An optical diagnostic based on resonant absorption of laser light in a plasma is introduced and is used for the determination of density scale lengths in the range of 10 nm to >1 μm at the critical surface of an overdense plasma. This diagnostic is also used to extract the plasma collisional frequency, allowing inference of the temporally evolving plasma composition on the tens of femtosecond timescale. This is found to be characterized by two eras: the early time and short scale length expansion (L  0.1λ); this is consistent with a hydrogen plasma decoupling from the bulk target material. Density gradients and plasma parameters on this scale are of importance to plasma mirror optical performance and comment is made on this theme
Determinants of the voltage dependence of G protein modulation within calcium channel β subunits
CaVβ subunits of voltage-gated calcium channels contain two conserved domains, a src-homology-3 (SH3) domain and a guanylate kinase-like (GK) domain with an intervening HOOK domain. We have shown in a previous study that, although Gβγ-mediated inhibitory modulation of CaV2.2 channels did not require the interaction of a CaVβ subunit with the CaVα1 subunit, when such interaction was prevented by a mutation in the α1 subunit, G protein modulation could not be removed by a large depolarization and showed voltage-independent properties (Leroy et al., J Neurosci 25:6984–6996, 2005). In this study, we have investigated the ability of mutant and truncated CaVβ subunits to support voltage-dependent G protein modulation in order to determine the minimal domain of the CaVβ subunit that is required for this process. We have coexpressed the CaVβ subunit constructs with CaV2.2 and α2δ-2, studied modulation by the activation of the dopamine D2 receptor, and also examined basal tonic modulation. Our main finding is that the CaVβ subunit GK domains, from either β1b or β2, are sufficient to restore voltage dependence to G protein modulation. We also found that the removal of the variable HOOK region from β2a promotes tonic voltage-dependent G protein modulation. We propose that the absence of the HOOK region enhances Gβγ binding affinity, leading to greater tonic modulation by basal levels of Gβγ. This tonic modulation requires the presence of an SH3 domain, as tonic modulation is not supported by any of the CaVβ subunit GK domains alone
Boundaries of Semantic Distraction: Dominance and Lexicality Act at Retrieval
Three experiments investigated memory for semantic information with the goal of determining boundary conditions for the manifestation of semantic auditory distraction. Irrelevant speech disrupted the free recall of semantic category-exemplars to an equal degree regardless of whether the speech coincided with presentation or test phases of the task (Experiment 1) and occurred regardless of whether it comprised random words or coherent sentences (Experiment 2). The effects of background speech were greater when the irrelevant speech was semantically related to the to-be-remembered material, but only when the irrelevant words were high in output dominance (Experiment 3). The implications of these findings in relation to the processing of task material and the processing of background speech is discussed
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