319 research outputs found
Thirty years of research on Crown-of-Thorns Starfish (1986–2016): Scientific advances and emerging opportunities
Research on the coral-eating crown-of-thorns starfish (CoTS) has waxed and waned over the last few decades, mostly in response to population outbreaks at specific locations. This review considers advances in our understanding of the biology and ecology of CoTS based on the resurgence of research interest, which culminated in this current special issue on the Biology, Ecology and Management of Crown-of-Thorns Starfish. More specifically, this review considers progress in addressing 41 specific research questions posed in a seminal review by P. Moran 30 years ago, as well as exploring new directions for CoTS research. Despite the plethora of research on CoTS ( > 1200 research articles), there are persistent knowledge gaps that constrain effective management of outbreaks. Although directly addressing some of these questions will be extremely difficult, there have been considerable advances in understanding the biology of CoTS, if not the proximate and ultimate cause(s) of outbreaks. Moving forward, researchers need to embrace new technologies and opportunities to advance our understanding of CoTS biology and behavior, focusing on key questions that will improve effectiveness of management in reducing the frequency and likelihood of outbreaks, if not preventing them altogether
Nab: Measurement Principles, Apparatus and Uncertainties
The Nab collaboration will perform a precise measurement of 'a', the
electron-neutrino correlation parameter, and 'b', the Fierz interference term
in neutron beta decay, in the Fundamental Neutron Physics Beamline at the SNS,
using a novel electric/magnetic field spectrometer and detector design. The
experiment is aiming at the 10^{-3} accuracy level in (Delta a)/a, and will
provide an independent measurement of lambda = G_A/G_V, the ratio of
axial-vector to vector coupling constants of the nucleon. Nab also plans to
perform the first ever measurement of 'b' in neutron decay, which will provide
an independent limit on the tensor weak coupling.Comment: 12 pages, 6 figures, 1 table, talk presented at the International
Workshop on Particle Physics with Slow Neutrons, Grenoble, 29-31 May 2008; to
appear in Nucl. Instrum. Meth. in Physics Research
On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection
A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)
New Caledonian crows rapidly solve a collaborative problem without cooperative cognition
There is growing comparative evidence that the cognitive bases of cooperation are not unique to humans. However, the selective pressures that lead to the evolution of these mechanisms remain unclear. Here we show that while tool-making New Caledonian crows can produce collaborative behavior, they do not understand the causality of cooperation nor show sensitivity to inequity. Instead, the collaborative behavior produced appears to have been underpinned by the transfer of prior experience. These results suggest that a number of possible selective pressures, including tool manufacture and mobbing behaviours, have not led to the evolution of cooperative cognition in this species. They show that causal cognition can evolve in a domain specific manner-understanding the properties and flexible uses of physical tools does not necessarily enable animals to grasp that a conspecific can be used as a social tool
A breeding index to rank beef bulls for use on dairy females to maximize profit
peer-reviewedThe desire to increase profit on dairy farms necessitates consideration of the revenue attainable from the sale of surplus calves for meat production. However, the generation of calves that are expected to excel in efficiency of growth and carcass merit must not be achieved to the detriment of the dairy female and her ability to calve and re-establish pregnancy early postcalving without any compromise in milk production. Given the relatively high heritability of many traits associated with calving performance and carcass merit, and the tendency for many of these traits to be moderately to strongly antagonistic, a breeding index that encompasses both calving performance and meat production could be a useful tool to fill the void in supporting decisions on bull selection. The objective of the present study was to derive a dairy–beef index (DBI) framework to rank beef bulls for use on dairy females with the aim of striking a balance between the efficiency of valuable meat growth in the calf and the subsequent performance of the dam. Traits considered for inclusion in this DBI were (1) direct calving difficulty; (2) direct gestation length; (3) calf mortality; (4) feed intake; (5) carcass merit reflected by carcass weight, conformation, and fat and the ability to achieve minimum standards for each; (6) docility; and (7) whether the calf was polled. Each trait was weighted by its respective economic weight, most of which were derived from the analyses of available phenotypic data, supplemented with some assumptions on costs and prices. The genetic merit for a range of performance metrics of 3,835 artificial insemination beef bulls from 14 breeds ranked on this proposed DBI was compared with an index comprising only direct calving difficulty and gestation length (the 2 generally most important characteristics of dairy farmers when selecting beef bulls). Within the Angus breed (i.e., the beef breed most commonly used on dairy females), the correlation between the DBI and the index of genetic merit for direct calving difficulty plus gestation length was 0.74; the mean of the within-breed correlations across all other breeds was 0.87. The ranking of breeds changed considerably when ranked based on the top 20 artificial insemination bulls excelling in the DBI versus excelling in the index of calving difficulty and gestation length. Dairy breeds ranked highest on the index of calving difficulty and gestation length, whereas the Holstein and Friesian breeds were intermediate on the DBI; the Jersey breed was one of the poorest breeds on DBI, superior only to the Charolais breed. The results clearly demonstrate that superior carcass and growth performance can be achieved with the appropriate selection of beef bulls for use on dairy females with only a very modest increase in collateral effect on cow performance (i.e., 2–3% greater dystocia expected and a 6-d-longer gestation length)
Operation of an optoelectronic crossbar switch containing a terabit-per-second free-space optical interconnect
The experimental operation of a terabit-per-second scale optoelectronic connection to a silicon very-large-scale-integrated circuit is described. A demonstrator system, in the form of an optoelectronic crossbar switch, has been constructed as a technology test bed. The assembly and testing of the components making up the system, including a flip-chipped InGaAs-GaAs optical interface chip, are reported. Using optical inputs to the electronic switching chip, single-channel routing of data through the system at the design rate of 250 Mb/s (without internal fan-out) was achieved. With 4000 optical inputs, this corresponds to a potential aggregate data input of a terabit per second into the single 14.6 /spl times/ 15.6 mm CMOS chip. In addition 50-Mb/s data rates were switched utilizing the full internal optical fan-out included in the system to complete the required connectivity. This simultaneous input of data across the chip corresponds to an aggregate data input of 0.2 Tb/s. The experimental system also utilized optical distribution of clock signals across the CMOS chip
Multifunctional Magnetic-fluorescent Nanocomposites for Biomedical Applications
Nanotechnology is a fast-growing area, involving the fabrication and use of nano-sized materials and devices. Various nanocomposite materials play a number of important roles in modern science and technology. Magnetic and fluorescent inorganic nanoparticles are of particular importance due to their broad range of potential applications. It is expected that the combination of magnetic and fluorescent properties in one nanocomposite would enable the engineering of unique multifunctional nanoscale devices, which could be manipulated using external magnetic fields. The aim of this review is to present an overview of bimodal “two-in-one” magnetic-fluorescent nanocomposite materials which combine both magnetic and fluorescent properties in one entity, in particular those with potential applications in biotechnology and nanomedicine. There is a great necessity for the development of these multifunctional nanocomposites, but there are some difficulties and challenges to overcome in their fabrication such as quenching of the fluorescent entity by the magnetic core. Fluorescent-magnetic nanocomposites include a variety of materials including silica-based, dye-functionalised magnetic nanoparticles and quantum dots-magnetic nanoparticle composites. The classification and main synthesis strategies, along with approaches for the fabrication of fluorescent-magnetic nanocomposites, are considered. The current and potential biomedical uses, including biological imaging, cell tracking, magnetic bioseparation, nanomedicine and bio- and chemo-sensoring, of magnetic-fluorescent nanocomposites are also discussed
Use of Opuntia ficus-indica (L.) Mill extracts from Brazilian Caatinga as an alternative of natural moisturizer in cosmetic formulations
ABSTRACT The aim of this work was the obtainment of Opuntia fícus-indica (L.) Mill extract for the development of cosmetic formulations and in vivo evaluation of its moisturizing effects. The formulations were tested for preliminary and accelerated stability. Organoleptic characteristics, pH values and rheological behavior were assessed. The evaluation of moisturizing efficacy of the emulsions formulated with 3.0% of Polyacrylamide (and) C13-14 Isoparaffin (and) Laureth-7 containing 1.0 and 3.0% of O. ficus-indica hydroglycolic extract (EHG001) was performed using the capacitance method (Corneometer(r)) and the transepidermal water loss - TEWL evaluation (Tewameter(r)). The emulsions formulated were stable, exhibiting pseudoplastic and thixotropic behavior. The results of evaluation of moisturizing efficacy showed increased skin hydration after five hours by mainly increasing the skin barrier effect. The formulations containing 1.0 and 3.0% of EHG001 enhanced the skin barrier effect by reducing TEWL up to four hours after application. The results observed suggest that O. ficus-indica hydroglycolic extract may act through a humectant and occlusion mechanism
Operation of an optoelectronic crossbar switch containing a terabit-per-second free-space optical interconnect
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