Multichannel pulse height analyzer is inexpensive, features low power requirements

Consumption multichannel pulse height analyzer performs balloon and rocket investigations of solar neutrons with energies greater than 10 MeV. The lightweight unit can operate in a temperature range of minus 30 degrees to plus 70 degrees C and withstand storage temperatures from minus 50 degrees to plus 90 degrees C

Wavefront sensing of atmospheric phase distortions at the Palomar 200-in. telescope and implications for adaptive optics

Major efforts in astronomical instrumentation are now being made to apply the techniques of adaptive optics to the correction of phase distortions induced by the turbulent atmosphere and by quasi-static aberrations in telescopes themselves. Despite decades of study, the problem of atmospheric turbulence is still only partially understood. We have obtained video-rate (30 Hz) imaging of stellar clusters and of single-star phase distortions over the pupil of the 200" Hale telescope on Palomar Mountain. These data show complex temporal and spatial behavior, with multiple components arising at a number of scale heights in the atmosphere; we hope to quantify this behavior to ensure the feasibility of adaptive optics at the Observatory. We have implemented different wavefront sensing techniques to measure aperture phase in wavefronts from single stars, including the classical Foucault test, which measures the local gradient of phase, and the recently-devised curvature sensing technique, which measures the second derivative of pupil phase and has formed the real-time wavefront sensor for some very productive astronomical adaptive optics. Our data, though not fast enough to capture all details of atmospheric phase fluctuations, provide important information regarding the capabilities that must be met by the adaptive optics system now being built for the 200" telescope by a team at the Jet Propulsion Lab. We describe our data acquisition techniques, initial results from efforts to characterize the properties of the turbulent atmosphere at Palomar Mountain, and future plans to extract additional quantitative parameters of use for adaptive optics performance predictions

The grey partridge in the UK: population status, research, policy and prospects

La perdiz pardilla en el Reino Unido: estado de la población, investigación, gestión y perspectivas Durante los últimos cincuenta años, los efectivos de la perdiz pardilla (Perdix perdix) han descendido catastróficamente en el Reino Unido. Por el contrario, el Programa de Recuento de la Perdiz de la GWCT (Fundación para la Conservación de la Caza y la Fauna Salvaje) presenta un 81% de aumento desde el año 2000 en los lugares del Reino Unido en que interviene. En este estudio exploramos los antecedentes y las razones de estos resultados tan contradictorios. Las investigaciones de la GWCT han tenido como consecuencias recomendaciones científicamente demostradas para la mejora del medio ambiente de la perdiz en el Reino Unido, desde los requerimientos del hábitat hasta la densidad de depredadores. Dichas investigaciones han influido en la política gubernamental del Reino Unido, que ahora incluye uno de los proyectos de Europa más orientadas hacia la conservación y más flexible en cuanto a hábitat y agricultura, lo que permite a los gestores del territorio recuperar gran parte del hábitat costero de la perdiz pardilla. Actualmente, los proyectos sobre agricultura y medio ambiente no abarcan la selección de los depredadores más comunes, de manera que son principalmente los cotos de caza con guardabosques privados los que han aplicado todas las medidas de gestión. El futuro de la perdiz pardilla en el Reino Unido reside en el equilibrio entre la economía de la producción agrícola, las medidas agro–medioambientales, y la caza.La perdiz pardilla en el Reino Unido: estado de la población, investigación, gestión y perspectivas Durante los últimos cincuenta años, los efectivos de la perdiz pardilla (Perdix perdix) han descendido catastróficamente en el Reino Unido. Por el contrario, el Programa de Recuento de la Perdiz de la GWCT (Fundación para la Conservación de la Caza y la Fauna Salvaje) presenta un 81% de aumento desde el año 2000 en los lugares del Reino Unido en que interviene. En este estudio exploramos los antecedentes y las razones de estos resultados tan contradictorios. Las investigaciones de la GWCT han tenido como consecuencias recomendaciones científicamente demostradas para la mejora del medio ambiente de la perdiz en el Reino Unido, desde los requerimientos del hábitat hasta la densidad de depredadores. Dichas investigaciones han influido en la política gubernamental del Reino Unido, que ahora incluye uno de los proyectos de Europa más orientadas hacia la conservación y más flexible en cuanto a hábitat y agricultura, lo que permite a los gestores del territorio recuperar gran parte del hábitat costero de la perdiz pardilla. Actualmente, los proyectos sobre agricultura y medio ambiente no abarcan la selección de los depredadores más comunes, de manera que son principalmente los cotos de caza con guardabosques privados los que han aplicado todas las medidas de gestión. El futuro de la perdiz pardilla en el Reino Unido reside en el equilibrio entre la economía de la producción agrícola, las medidas agro–medioambientales, y la caza.Numbers of grey partridges (Perdix perdix) have declined catastrophically over the last 50 years in the UK. By contrast, the Partridge Count Scheme of the Game & Wildlife Conservation Trust (GWCT) shows an 81% increase on participating UK sites since 2000. We explore the background and reasons for this conflicting picture. GWCT research has led to scientifically proven recommendations for improving the UK partridge environment, ranging from habitat requirements to predator density. The research has influenced UK government policy, which now includes one of the most conservation–oriented and flexible agri–environment schemes in Europe, allowing land managers to recover much of the cost of grey partridge habitat creation. Culling common predators is not covered by agri–environment schemes, so it is primarily shooting estates with private gamekeepers that have implemented the full package of management measures. The future fate of the grey partridge in the UK rests on the balance between the economics of agricultural production, agri–environment measures and shooting

Fully covariant and conformal formulation of the Z4 system in a reference-metric approach: comparison with the BSSN formulation in spherical symmetry

We adopt a reference-metric approach to generalize a covariant and conformal version of the Z4 system of the Einstein equations. We refer to the resulting system as ``fully covariant and conformal", or fCCZ4 for short, since it is well suited for curvilinear as well as Cartesian coordinates. We implement this fCCZ4 formalism in spherical polar coordinates under the assumption of spherical symmetry using a partially-implicit Runge-Kutta (PIRK) method and show that our code can evolve both vacuum and non-vacuum spacetimes without encountering instabilities. Our method does not require regularization of the equations to handle coordinate singularities, nor does it depend on constraint-preserving outer boundary conditions, nor does it need any modifications of the equations for evolutions of black holes. We perform several tests and compare the performance of the fCCZ4 system, for different choices of certain free parameters, with that of BSSN. Confirming earlier results we find that, for an optimal choice of these parameters, and for neutron-star spacetimes, the violations of the Hamiltonian constraint can be between 1 and 3 orders of magnitude smaller in the fCCZ4 system than in the BSSN formulation. For black-hole spacetimes, on the other hand, any advantages of fCCZ4 over BSSN are less evident.Comment: 13 pages, 10 figure

Restoration of a wild grey partridge shoot: a major development in the Sussex study, UK

Restauración de la caza de la perdiz pardilla: un importante progreso en el estudio de Sussex, Reino Unido Desde hace una generación se conoce la base científica de la gestión de la perdiz pardilla. Ésta incluye el control de los depredadores de nidos, la provisión de material para la nidificación, tener suficientes insectos para alimentar a las crías, y un control adecuado de la caza. Más recientemente también se ha considerado importante proveer alimento para las aves adultas y y hábitats para protegerlas de las aves rapaces. El abastecimiento del hábitat puede ser caro, pero en el Reino Unido los costos pueden recuperarse parcialmente mediante proyectos agro-medioambientales. El propietario de la tierra aún tiene que pagar por los servicios de los guardabosques. Desde 2003/2004, una parte del área de estudio de Sussex de la GWCT ha puesto en práctica estos principios de gestión ambiental, con la intención de restaurar la caza de la perdiz pardilla en esta zona del sur de Inglaterra. Los resultados han sido impresionantes, con un aumento de la densidad de parejas en primavera de 0,3/100 ha en 2003 hasta casi 20 parejas/100 ha en el 2010, en un área total de más de 10 km2. Durante los últimos dos años se ha practicado la caza de la perdiz pardilla y los propietarios de las tierras y sus equipos se han ganado el reconocimiento nacional por su labor conservacionista.Restauración de la caza de la perdiz pardilla: un importante progreso en el estudio de Sussex, Reino Unido Desde hace una generación se conoce la base científica de la gestión de la perdiz pardilla. Ésta incluye el control de los depredadores de nidos, la provisión de material para la nidificación, tener suficientes insectos para alimentar a las crías, y un control adecuado de la caza. Más recientemente también se ha considerado importante proveer alimento para las aves adultas y y hábitats para protegerlas de las aves rapaces. El abastecimiento del hábitat puede ser caro, pero en el Reino Unido los costos pueden recuperarse parcialmente mediante proyectos agro-medioambientales. El propietario de la tierra aún tiene que pagar por los servicios de los guardabosques. Desde 2003/2004, una parte del área de estudio de Sussex de la GWCT ha puesto en práctica estos principios de gestión ambiental, con la intención de restaurar la caza de la perdiz pardilla en esta zona del sur de Inglaterra. Los resultados han sido impresionantes, con un aumento de la densidad de parejas en primavera de 0,3/100 ha en 2003 hasta casi 20 parejas/100 ha en el 2010, en un área total de más de 10 km2. Durante los últimos dos años se ha practicado la caza de la perdiz pardilla y los propietarios de las tierras y sus equipos se han ganado el reconocimiento nacional por su labor conservacionista.The scientific basis of wild grey partridge management has been known for a generation. This includes controlling nest predators, providing nesting cover, having sufficient insect food for chicks and appropriate rates of shooting. More recently, measures such as providing food for adult birds and habitats for protection from birds of prey have also been considered important. Habitat provision can be expensive, but in the UK costs can be partially recovered through governmental agri–environment schemes. The landowner still needs to pay for the essential gamekeeper. Since 2003/04, one part of the Game & Wildlife Conservation Trust’s (GWCT) Sussex Study area has put these principles of environmental management into practice with the aim of restoring a wild grey partridge shoot to this part of Southern England. Results have been impressive, with the spring pair density increasing from 0.3 pairs/100 ha in 2003 to nearly 20 pairs/100 ha in 2010 on an area of just over 10 km2. Over the past two years a wild grey partridge shoot has taken place, and the landowner and his team have gained national recognition for their conservation work

Heliostat-array wind-tunnel study

CER78-79RLE-JAP-JEC31.Prepared for Martin Marietta Aerospace.Includes bibliographical references (page 24).January 1979

Mitofusins Mfn1 and Mfn2 coordinately regulate mitochondrial fusion and are essential for embryonic development

Mitochondrial morphology is determined by a dynamic equilibrium between organelle fusion and fission, but the significance of these processes in vertebrates is unknown. The mitofusins, Mfn1 and Mfn2, have been shown to affect mitochondrial morphology when overexpressed. We find that mice deficient in either Mfn1 or Mfn2 die in midgestation. However, whereas Mfn2 mutant embryos have a specific and severe disruption of the placental trophoblast giant cell layer, Mfn1-deficient giant cells are normal. Embryonic fibroblasts lacking Mfn1 or Mfn2 display distinct types of fragmented mitochondria, a phenotype we determine to be due to a severe reduction in mitochondrial fusion. Moreover, we find that Mfn1 and Mfn2 form homotypic and heterotypic complexes and show, by rescue of mutant cells, that the homotypic complexes are functional for fusion. We conclude that Mfn1 and Mfn2 have both redundant and distinct functions and act in three separate molecular complexes to promote mitochondrial fusion. Strikingly, a subset of mitochondria in mutant cells lose membrane potential. Therefore, mitochondrial fusion is essential for embryonic development, and by enabling cooperation between mitochondria, has protective effects on the mitochondrial population

Wind-tunnel study of wind over an offshore platform helideck

CER78-79RE-JAP-JBC25.Prepared for Earl and Wright Consulting Engineers.Includes bibliographical references (page 16).December 1978

Evolutionary bi-stability in pathogen transmission mode

Many pathogens transmit to new hosts by both infection (horizontal transmission) and transfer to the infected host's offspring (vertical transmission). These two transmission modes require speci®c adap- tations of the pathogen that can be mutually exclusive, resulting in a trade-off between horizontal and vertical transmission. We show that in mathematical models such trade-offs can lead to the simultaneous existence of two evolutionary stable states (evolutionary bi-stability) of allocation of resources to the two modes of transmission. We also show that jumping between evolutionary stable states can be induced by gradual environmental changes. Using quantitative PCR-based estimates of abundance in seed and vege- tative parts, we show that the pathogen of wheat, Phaeosphaeria nodorum, has jumped between two distinct states of transmission mode twice in the past 160 years, which, based on published evidence, we interpret as adaptation to environmental change. The ®nding of evolutionary bi-stability has impli- cations for human, animal and other plant diseases. An ill-judged change in a disease control programme could cause the pathogen to evolve a new, and possibly more damaging, combination of transmission modes. Similarly, environmental changes can shift the balance between transmission modes, with adverse effects on human, animal and plant health

Systematic {\it ab initio} study of the magnetic and electronic properties of all 3d transition metal linear and zigzag nanowires

It is found that all the zigzag chains except the nonmagnetic (NM) Ni and antiferromagnetic (AF) Fe chains which form a twisted two-legger ladder, look like a corner-sharing triangle ribbon, and have a lower total energy than the corresponding linear chains. All the 3d transition metals in both linear and zigzag structures have a stable or metastable ferromagnetic (FM) state. The electronic spin-polarization at the Fermi level in the FM Sc, V, Mn, Fe, Co and Ni linear chains is close to 90% or above. In the zigzag structure, the AF state is more stable than the FM state only in the Cr chain. It is found that the shape anisotropy energy may be comparable to the electronic one and always prefers the axial magnetization in both the linear and zigzag structures. In the zigzag chains, there is also a pronounced shape anisotropy in the plane perpendicular to the chain axis. Remarkably, the axial magnetic anisotropy in the FM Ni linear chain is gigantic, being ~12 meV/atom. Interestingly, there is a spin-reorientation transition in the FM Fe and Co linear chains when the chains are compressed or elongated. Large orbital magnetic moment is found in the FM Fe, Co and Ni linear chains