Two techniques enable sampling of filtered and unfiltered molten metals

Filtered samples of molten metals are obtained by filtering through a plug of porous material fitted in the end of a sample tube, and unfiltered samples are obtained by using a capillary-tube extension rod with a perforated bucket. With these methods there are no sampling errors or loss of liquid

Cosmic antiprotons as a probe for supersymmetric dark matter?

The flux of cosmic ray antiprotons from neutralino annihilations in the galactic halo is computed for a large sample of models in the MSSM (the Minimal Supersymmetric extension of the Standard Model). We also revisit the problem of estimating the background of low-energy cosmic ray induced secondary antiprotons, taking into account their subsequent interactions (and energy loss) and the presence of nuclei in the interstellar matter. We consider a two-zone diffusion model, with and without a galactic wind. We find that, given the uncertainties in the background predictions, there is no need for a primary (exotic) component to explain present data. However, allowing for a signal by playing with the uncertainties in the background estimate, we discuss the characteristic features of the supersymmetric models which give a satisfactory description of the data. We point out that in some cases the optimal kinetic energy to search for a signal from supersymmetric dark matter is above several GeV, rather than the traditional sub-GeV region. The large astrophysical uncertainties involved do not, one the other hand, allow the exclusion of any of the MSSM models we consider, on the basis of data. We present besides numerical results also convenient parameterizations of the antiproton yields of all `basic' two-body final states. We also give examples of the yield and differential energy spectrum for a set of supersymmetric models with high rates. We also remark that it is difficult to put a limit on the antiproton lifetime from present measurements, since the injection of antiprotons from neutralino annihilation can compensate the loss from decay.Comment: 22 pages, 11 figures, uses emulateapj.st

Effect of dietary fatty acid composition on depot fat and exercise performance in a migrating songbird, the red-eyed vireo

Most migrating birds accumulate lipid stores as their primary source of energy for fueling long distance flights. Lipid stores of birds during migration are composed of mostly unsaturated fatty acids; whether such a fatty acid composition enhances exercise performance of birds is unknown. We tested this hypothesis by measuring metabolic rate at rest and during intense exercise in two groups of red-eyed vireos, a long-distance migratory passerine, fed either a diet containing 82% unsaturated fat (82%U), or one containing 58% unsaturated fat (58%U). Vireos fed the 82%U diet had fat stores containing (77%) unsaturated fatty acids, whereas vireos fed the 58% U diet had fat stores containing less (66%) unsaturated fatty acids. Blood metabolites measured prior to and immediately following exercise confirmed that vireos were metabolizing endogenous fat during intense exercise. Mass-specific resting metabolic rate (RMR) was similar for vireos fed the 58%U diet (2.75±0.32 ml O2 g–1 h–1) and for vireos fed the 82%U diet (2.30±0.30 ml O2 g–1 h–1). However, mass-specific peak metabolic rate (MRpeak) was 25% higher in vireos fed the 58%U diet (28.55±1.47 ml O2 g–1 h–1) than in vireos fed the 82%U diet (21.50±1.76 ml O2 g–1 h–1). Such whole-animal energetic effects of fatty acid composition of birds suggest that the energetic cost of migration in birds may be affected by the fatty acid composition of the diet

Tracking and imaging gamma ray experiment (TIGRE) for 1 to 100 MEV gamma ray astronomy

A large international collaboration from the high energy astrophysics community has proposed the Tracking and Imaging Gamma Ray Experiment (TIGRE) for future space observations. TIGRE will image and perform energy spectroscopy measurements on celestial sources of gamma rays in the energy range from 1 to 100 MeV. This has been a difficult energy range experimentally for gamma ray astronomy but is vital for the future considering the recent exciting measurements below 1 and above 100 MeV. TIGRE is both a double scatter Compton and gamma ray pair telescope with direct imaging of individual gamma ray events. Multi‐layers of Si strip detectors are used as Compton and pair converters CsI(Tl) scintillation detectors are used as a position sensitive calorimeter. Alternatively, thick GE strip detectors may be used for the calorimeter. The Si detectors are able to track electrons and positrons through successive Si layers and measure their directions and energy losses. Compton and pair events are completely reconstructed allowing each event to be imaged on the sky. TIGRE will provide an order‐of‐magnitude improvement in discrete source sensitivity in the 1 to 100 MeV energy range and determine spectra with excellent energy and excellent angular resolutions. It’s wide field‐of‐view of π sr permits observations of the entire sky for extended periods of time over the life of the mission

Sun-as-a-Star Spectrum Variations 1974-2006

We have observed selected Fraunhofer lines, both integrated over the Full Disk and for a small circular region near the center of the solar disk, on 1,215 days for the past 30 years. Full Disk results: Ca II K 393 nm nicely tracks the 11 year magnetic cycle based on sunspot number with a peak amplitude in central intensity of ~37%. The wavelength of the mid-line core absorption feature, called K3, referenced to nearby photospheric Fe, displays an activity cycle variation with an amplitude of 3 milli-Angstroms. Other chromospheric lines track Ca II K intensity with lower relative amplitudes. Low photosphere: Temperature sensitive CI 5380 nm appears constant in intensity to 0.2%. High photosphere: The cores of strong Fe I lines, Na D1 and D2, and the Mg I b lines, present a puzzling signal perhaps indicating a role for the 22 y Hale cycle. Solar minimum around 1985 was clearly seen, but the following minimum in 1996 was missing. This anomalous behavior is not seen in comparison atmospheric O2. Center Disk results: Both Ca II K and C I 538 nm intensities are constant, indicating that the basal quiet atmosphere is unaffected by cycle magnetism within our observational error. A lower limit to the Ca II K central intensity atmosphere is 0.040. The wavelength of Ca II K3 varies with the cycle by 6 milli-Angstroms, a factor of 2X over the full disk value. This may indicate the predominance of radial motions at Center Disk. This is not an effect of motions in plages since they are absent at Center Disk. This 11 y variation in the center of chromospheric lines could complicate the radial velocity detection of planets around solar-type stars. An appendix provides instructions for URL access to both the raw and reduced data.Comment: 38 pages with 20 figures. Accepted for publication in The Astrophysical Journa

Disorder-induced magnetic memory: Experiments and theories

Beautiful theories of magnetic hysteresis based on random microscopic disorder have been developed over the past ten years. Our goal was to directly compare these theories with precise experiments. We first developed and then applied coherent x-ray speckle metrology to a series of thin multilayer perpendicular magnetic materials. To directly observe the effects of disorder, we deliberately introduced increasing degrees of disorder into our films. We used coherent x-rays to generate highly speckled magnetic scattering patterns. The apparently random arrangement of the speckles is due to the exact configuration of the magnetic domains in the sample. In effect, each speckle pattern acts as a unique fingerprint for the magnetic domain configuration. Small changes in the domain structure change the speckles, and comparison of the different speckle patterns provides a quantitative determination of how much the domain structure has changed. How is the magnetic domain configuration at one point on the major hysteresis loop related to the configurations at the same point on the loop during subsequent cycles? The microscopic return-point memory(RPM) is partial and imperfect in the disordered samples, and completely absent when the disorder was not present. We found the complementary-point memory(CPM) is also partial and imperfect in the disordered samples and completely absent when the disorder was not present. We found that the RPM is always a little larger than the CPM. We also studied the correlations between the domains within a single ascending or descending loop. We developed new theoretical models that do fit our experiments.Comment: 26 pages, 25 figures, Accepted by Physical Review B 01/25/0

Development of StressCheck: A telehealth motivational enhancement therapy to improve voluntary engagement for PTSD treatment among active-duty service members

Background: Rates of PTSD in active-duty military are high relative to the general population. Although efficacious treatments exist, they are underutilized. Many service members with PTSD do not present for treatment and, of those who do, many do not receive sufficient doses of the interventions to receive full benefits. Motivational Enhancement Therapy (MET) “check-ups”, are brief interventions designed to elicit treatment engagement for those who are not treatment-seeking. Methods: StressCheck is an MET for nontreatment seeking Army and Air Force personnel. StressCheck aims to improve PTSD and increase treatment engagement, especially around evidence-based interventions, as well as to decrease stigma about seeking mental health services and improve knowledge about treatment options. This paper describes the intervention components and process of treatment development. The paper also describes next steps in testing the effectiveness of the intervention. Conclusion: PTSD is associated with deleterious health, occupational, and psychological effects. If effective, this innovative intervention will bridge the gap between those who are not treatment seeking and existing services, thereby enhancing reach and impact of existing services

Disorder-induced microscopic magnetic memory

Using coherent x-ray speckle metrology, we have measured the influence of disorder on major loop return point memory (RPM) and complementary point memory (CPM) for a series of perpendicular anisotropy Co/Pt multilayer films. In the low disorder limit, the domain structures show no memory with field cycling--no RPM and no CPM. With increasing disorder, we observe the onset and the saturation of both the RPM and the CPM. These results provide the first direct ensemble-sensitive experimental study of the effects of varying disorder on microscopic magnetic memory and are compared against the predictions of existing theories.Comment: 4 pages, 4 figures. Accepted for publication in Physical Review Letters in Nov. 200

Comparison of Satellite Observations of Nitrogen Dioxide to Surface Monitor Nitrogen Dioxide Concentration

Nitrogen dioxide is one of the U. S. EPA s criteria pollutants, and one of the main ingredients needed for the production of ground-level ozone. Both ozone and nitrogen dioxide cause severe public health problems. Existing satellites have begun to produce observational data sets for nitrogen dioxide. Under NASAs Earth Science Applications Program, we examined the relationship between satellite observations and surface monitor observations of this air pollutant to examine if the satellite data can be used to facilitate a more capable and integrated observing network. This report provides a comparison of satellite tropospheric column nitrogen dioxide to surface monitor nitrogen dioxide concentration for the period from September 1996 through August 1997 at more than 300 individual locations in the continental US. We found that the spatial resolution and observation time of the satellite did not capture the variability of this pollutant as measured at ground level. The tools and processes developed to conduct this study will be applied to the analysis of advanced satellite observations. One advanced instrument has significantly better spatial resolution than the measurements studied here and operates with an afternoon overpass time, providing a more representative distribution for once-per-day sampling of this photochemically active atmospheric constituent