Two-magnon bound state causes ultrafast thermally induced magnetisation switching

There has been much interest recently in the discovery of thermally induced magnetisation switching using femtosecond laser excitation, where a ferrimagnetic system can be switched deterministically without an applied magnetic field. Experimental results suggest that the reversal occurs due to intrinsic material properties, but so far the microscopic mechanism responsible for reversal has not been identified. Using computational and analytic methods we show that the switching is caused by the excitation of two-magnon bound states, the properties of which are dependent on material factors. This discovery allows us to accurately predict the onset of switching and the identification of this mechanism will allow new classes of materials to be identified or designed for memory devices in the THz regime.

Permutationally invariant state reconstruction

Feasible tomography schemes for large particle numbers must possess, besides an appropriate data acquisition protocol, an efficient way to reconstruct the density operator from the observed finite data set. Since state reconstruction typically requires the solution of a nonlinear large-scale optimization problem, this is a major challenge in the design of scalable tomography schemes. Here we present an efficient state reconstruction scheme for permutationally invariant quantum state tomography. It works for all common state-of-the-art reconstruction principles, including, in particular, maximum likelihood and least squares methods, which are the preferred choices in today's experiments. This high efficiency is achieved by greatly reducing the dimensionality of the problem employing a particular representation of permutationally invariant states known from spin coupling combined with convex optimization, which has clear advantages regarding speed, control and accuracy in comparison to commonly employed numerical routines. First prototype implementations easily allow reconstruction of a state of 20 qubits in a few minutes on a standard computer

Neurotransmitter signaling in the pathophysiology of microglia

Erratun publicado en Frontiers in Cellular Neuroscience 7 : (2013) // Article ID 107

Janus-faced microglia: beneficial and detrimental consequences of microglial phagocytosis

Microglia are the resident brain macrophages and they have been traditionally studied as orchestrators of the brain inflammatory response during infections and disease. In addition, microglia has a more benign, less explored role as the brain professional phagocytes. Phagocytosis is a term coined from the Greek to describe the receptor-mediated engulfment and degradation of dead cells and microbes. In addition, microglia phagocytoses brain-specific cargo, such as axonal and myelin debris in spinal cord injury or multiple sclerosis, amyloid-beta deposits in Alzheimer's disease, and supernumerary synapses in postnatal development. Common mechanisms of recognition, engulfment, and degradation of the different types of cargo are assumed, but very little is known about the shared and specific molecules involved in the phagocytosis of each target by microglia. More importantly, the functional consequences of microglial phagocytosis remain largely unexplored. Overall, phagocytosis is considered a beneficial phenomenon, since it eliminates dead cells and induces an anti-inflammatory response. However, phagocytosis can also activate the respiratory burst, which produces toxic reactive oxygen species (ROS). Phagocytosis has been traditionally studied in pathological conditions, leading to the assumption that microglia have to be activated inorder to become efficient phagocytes. Recent data, however, has shown that unchallenged microglia phagocytose apoptotic cells during development and in adult neurogenic niches, suggesting an overlooked role in brain remodeling throughout the normal lifespan. The present review will summarize the current state of the literature regarding the role of microglial phagocytosis in maintaining tissue homeostasis in health as in disease.

Fault-tolerant almost exact state transmission

We show that a category of one-dimensional XY-type models may enable high-fidelity quantum state transmissions, regardless of details of coupling configurations. This observation leads to a fault-tolerant design of a state transmission setup. The setup is fault-tolerant, with specified thresholds, against engineering failures of coupling configurations, fabrication imperfections or defects, and even time-dependent noises. We propose an experimental implementation of the fault-tolerant scheme using hard-core bosons in one-dimensional optical lattices.

Effects of beach remourishment on the benthic macrofauna and the fishes of the nearshore zone at Sebastian Inlet State Recreation Area

Approximately 100,000 cubic yards of sand was transported to the ocean beach to renourish the eroded beach front during the period December 1985 through May 1986. The ocean beach at Sebastian Inlet SRA was previously studied in a project examining the benthic macrofauna and the fishes of the nearshore zone during 1981-1982 (Allenbaugh, 1984; Peters, 1984; Nelson, unpublished). In view of the existing data, the US Army Corps of Engineers provided funding to study the effects of the beach renourishment activities at Sebastian Inlet SRA on the benthic macrofauna and the fishes of the nearshore zone. This is the report on the results of this study.

State of Technology for In Situ Measures of Salinity Using Conductive Temperature Sensors, Savannah, Georgia, December 3-5, 2007: workshop proceedings

This Alliance for Coastal Technologies (ACT) workshop was convened to assess the availability and state of development of conductivity-temperature sensors that can meet the needs of coastal monitoring and management communities. Rased on the discussion, there are presently a number of commercial sensor options available, with a wide range of package configurations suitable for deployment in a range of coastal environments. However, some of the central questions posed in the workshop planning documents were left somewhat unresolved. The workshop description emphasized coastal management requirements and, in particular, whether less expensive, easily deployed, lower-resolution instruments might serve many management needs. While several participants expressed interest in this class of conductivity-temperature sensors, based on input from the manufacturers, it is not clear that simply relaxing the present level of resolution of existing instruments will result in instruments of significantly lower unit cost. Conductivity-temperature sensors are available near or under the $1,000 unit cost that was operationally defined at the workshop as a breakpoint for what might be considered to be a "low cost" sensor. For the manufacturers, a key consideration before undertaking the effort to develop lower cost sensors is whether there will be a significant market. In terms of defining "low cost," it was also emphasized that the "life cycle costs" for a given instrument must be considered (e.g., including personnel costs for deployment and maintenance). An adequate market survey to demonstrate likely applications and a viable market for lower cost sensors is needed. Another topic for the workshop was the introduction to the proposed ACT verification for conductivity-temperature sensors. Following a summary of the process as envisioned by ACT, initial feedback was solicited. Protocol development will be pursued further in a workshop involving ACT personnel and conductivity-temperature sensor manufacturers.[PDF contains 28 pages]

Applications of in situ Fluorometers in Nearshore waters, Cape Elizabeth, Maine, February 2-4,2005: workshop proceedings

The Alliance for Coastal Technologies (ACT) Workshop "Applications of in situ Fluorometers in Nearshore Waters" was held in Cape Elizabeth, Maine, February 2-4,2005, with sponsorship by the Gulf of Maine Ocean Observing System (GoMOOS), one of the ACT partner organization. The purpose of the workshop was to explore recent trends in fluorometry as it relates to resource management applications in nearshore environments. Participants included representatives from state and federal environmental management agencies as well as research institutions, many of whom are currently using this technology in their research and management applications. Manufacturers and developers of fluorometric measuring systems also attended the meeting. The Workshop attendees discussed the historical and present uses of fluorometry technology and identified the great potential for its use by coastal managers to fulfill their regulatory and management objectives. Participants also identified some of the challenges associated with the correct use of Fluorometers to estimate biomass and the rate of primary productivity. The Workshop concluded that in order to expand the existing use of fluorometers in both academic and resource management disciplines, several issues concerning data collection, instrument calibration, and data interpretation needed to be addressed. Participants identified twelve recommendations, the top five of which are listed below: Recommendations 1) Develop a "Guide" that describes the most important aspects of fluorescence measurements. This guide should be written by an expert party, with both research and industry input, and should be distributed by all manufacturers with their instrumentation. The guide should also be made available on the ACT website as well as those of other relevant organizations. The guide should include discussions on the following topics: The benefits of using fluorometers in research and resource management applications; What fluorometers can and cannot provide in terms of measurements; The necessary assumptions required before applying fluorometry; Characterization and calibration of fluorometers; (pdf contains 32 pages)

Introduction of collection and distribution programme for the small-scale fisheries in Ondo State

Details are given of a programme for fresh fish collection and distribution in Ondo State, Nigeria. Collection centers, organization and managerial structure, collection scheme, trade system, price determination, management and distribution are described

Problems of industrial fisheries development in the Cross River State

The industrial fisheries as opposed to artisanal fisheries in Cross River State, Nigeria, is discussed, considering the prospect of industrial fisheries in the State and identifying the major fish and shrimp resources within the coastal waters. Industrial fishing was introduced in 1973 when the state government invited a Japaneese company to carry out a joint exploratory shrimp fishing venture. The contributions made by the Seastate Seafoods Company, the Eyib's Nutritional Food and the Arawak Fishing Companies towards the increase in the number of fishing fleet in the state are noted.

A review of the crayfish fishery of Nigeria with special reference to the Cross River State

The fishery for crayfish is of considerable importance in the maritime region of the Cross River State, Nigeria, where it forms an important occupation of a host of fishermen. Crayfish landings from this State contributed 11% to the national marine fish landings within the period 1980 to 1984 and also in the same period the volume of crayfish alone formed 26% of the marine fish landings within the State. The species exploited as crayfish include Palaemon hastatus; Hippolysmata hastatoides, and Macrobrachium sp; mixed with the larval, and juveniles of pink shrimp Panaeus dourarum. They are generally small in size ranging from 7 cm (maximum) to 2.5 cm. Crayfish are caught all year round along the Niger Delta, but particularly along the river estuaries and littoral waters of the Cross River State with the highest production occurring in March to May. Crayfish are usually smoked, and occasionally sun-dried, and they form an indispensable food item in the diet of the people of the entire southern States in particular and Nigeria in general. It appears that crayfish landings could be substantially increased without depleting the stock, if a proper exploratory survey is undertaken of the Niger delta, and the Cross River estuaries to chart potentially rich grounds of this resource

Market survey of the periwinkle Tympanotonus fuscatus in Rivers State: Sizes, prices, trade routes and exploitation levels

Tympanotonus fuscatus was collected from 23 markets through Rivers State (Nigeria), a few in neighbouring states, and from an unexploited population at Buguma. The size distribution of shells was determined,and information on prices and trade routes was also obtained. The mean shell length of specimens from the unexploited Buguma population was 46.4 mm, compared to 30.4 mm for the Buguma market samples. Mean sizes in other markets showed a geographic pattern: the smallest were from the Adoni-Ogoni-Opobo sector (28.1-30.9); the largest were from the Nembe-Brass sector (37.7-44.2) and Bendel State (35.7-45.6); The results suggest the population structure of Tympanotonus in much of Rivers State has been strongly impacted by overharvesting. They show that local market as well as some in Cross River State, are increasingly being supplied by road with specimens from the Benin River area of Bendel State. Differences between shell types; and relations between shell size, selling price and market distance from source, are also discussed