Discovery of a Spin-Down State Change in the LMC Pulsar B0540-69

We report the discovery of a large, sudden, and persistent increase in the spin-down rate of B0540-69, a young pulsar in the Large Magellanic Cloud, using observations from the Swift and RXTE satellites. The relative increase in the spin-down rate of 36% is unprecedented for B0540-69. No accompanying change in the spin rate is seen, and no change is seen in the pulsed X-ray emission from B0540-69 following the change in the spin-down rate. Such large relative changes in the spin-down rate are seen in the recently discovered class of 'intermittent pulsars', and we compare the properties of B0540-69 to such pulsars. We consider possible changes in the magnetosphere of the pulsar that could cause such a large change in the spin-down rate.Comment: 6 pages, 2 figures, accepted for publication in ApJ Letter

Modeling the Pulse Profiles of Millisecond Pulsars in the Second LAT Catalog of gamma-ray Pulsars

Significant gamma-ray pulsations have been detected from ~40 millisecond pulsars (MSPs) using 3 years of sky-survey data from the Fermi LAT and radio timing solutions from across the globe. We have fit the radio and gamma-ray pulse profiles of these MSPs using geometric versions of slot gap and outer gap gamma-ray emission models and radio cone and core models. For MSPs with radio and gamma-ray peaks aligned in phase we also explore low-altitude slot gap gamma-ray models and caustic radio models. The best-fit parameters provide constraints on the viewing geometries and emission sites. While the exact pulsar magnetospheric geometry is unknown, we can use the increased number of known gamma-ray MSPs to look for significant trends in the population which average over these uncertainties.Comment: 4 pages, 2 figures, to appear in the proceedings of the 5th International Symposium on High-Energy Astronom

Surface scattering properties estimated from modeling airborne multiple emission angle reflectance data

Here, researchers apply the Hapke function to airborne bidirectional reflectance data collected over three terrestrial surfaces. The objectives of the study were to test the range of natural surfaces that the Hapke model fits and to evaluate model parameters in terms of known surface properties. The data used are multispectral and multiple emission angle data collected during the Geologic Remote Sensing Field Experiment (GRSFE) over a mud-cracked playa, an artificially roughened playa, and a basalt cobble strewn playa at Lunar Lake Playa in Nevada. Airborne remote sensing data and associated field measurements were acquired at the same time. The airborne data were acquired by the Advanced Solid State Array Spectroradiometer (ASAS) instrument, a 29-spectral band imaging system. ASAS reflectance data for a cobble-strewn surface and an artificially rough playa surface on Lunar Lake Playa can be explained with the Hanke model. The cobble and rough playa sites are distinguishable by a single scattering albedo, which is controlled by material composition; by the roughness parameter, which appears to be controlled by the surface texture and particle size; and the symmetry factor of the single particle phase function, which is controlled by particle size and shape. A smooth playa surface consisting of compacted, fine-grained particles has reflectance variations that are also distinct from either the cobble site or rough playa site. The smooth playa appears to behave more like a Lambertian surface that cannot be modeled with the Hapke function

Identification of premature infant states in relation to introducing oral feeding

Background Recognizing oral readiness signs in infants is vital when planning the introduction of oral feeding. However, with premature infants, this can be difficult to gauge accurately because of immature development. Methods Twenty three staff from a level 2 neonatal unit participated. A questionnaire elicited knowledge about oral readiness and other factors related to oral feeding with premature infants. Participant knowledge of the written Als (1986) infant state descriptors was completed. A comparison was made of the skills in identification of the various infant states on video without and with written descriptors (Als, 1986). Correlations investigated if years of experience and grade had any relation to accurate infant state identification. Results There was wide variation in the type of training about premature infant feeding participants had received. Participants (65%) recognized the importance of oral readiness signs in relation to feeding development. A Wilcoxon signed ranks test revealed no significant differences in ability to identify infant states without and with the written Als (1986) descriptors when observing infant video materials. When not using the written descriptors, there was a strong negative correlation between grade and the identification of the [Active sleep] state, (p < 0.01), and a strong positive correlation between grade and the identification of the [Drowsy] state, (p < 0.05). There were no strong correlations between grade and years working when using the written descriptors. Conclusion Oral readiness signs are important when introducing oral feeding with premature infants. However, accurate identification of oral readiness remains challenging

Symbiotic unicellular cyanobacteria fix nitrogen in the Arctic Ocean.

Biological dinitrogen (N2) fixation is an important source of nitrogen (N) in low-latitude open oceans. The unusual N2-fixing unicellular cyanobacteria (UCYN-A)/haptophyte symbiosis has been found in an increasing number of unexpected environments, including northern waters of the Danish Straight and Bering and Chukchi Seas. We used nanoscale secondary ion mass spectrometry (nanoSIMS) to measure 15N2 uptake into UCYN-A/haptophyte symbiosis and found that UCYN-A strains identical to low-latitude strains are fixing N2 in the Bering and Chukchi Seas, at rates comparable to subtropical waters. These results show definitively that cyanobacterial N2 fixation is not constrained to subtropical waters, challenging paradigms and models of global N2 fixation. The Arctic is particularly sensitive to climate change, and N2 fixation may increase in Arctic waters under future climate scenarios

Drinking speed using a Pat Saunders valved straw, wide-bore straw and a narrow-bore straw in a normal adult population

Background: Straw drinking is often recommended as a strategy for managing swallowing difficulties in adult clinical populations. This study presents a range of normal adult straw drinking speeds and discusses clinical applications. Method: Straw drinking speed in a normal healthy population of 70 adults from 18 to 95 years of age was measured. Three types of straws were used: a Pat Saunders valved straw (PSVS), a wide-bore straw and a narrow-bore straw (NBS). Participants drank 40 ml of water for each straw tested. All participants were asked to comment on the straws used. A mixed-method design was used wherein both quantitative and simple structured qualitative data were collected. Results: Drinking speed was quickest for the wide-bore straw, followed by the NBS and slowest for the PSVS. This was supported by qualitative comments from the adults who reported that the PSVS was the most difficult straw to use. There were no significant differences between straw flow or straw type and sex of the participants. There were significant changes with aging and a decrease in flow speed with the NBS. Weight and height had some effect on straw drinking speeds. There was a slight correlation between age and sex and age and height, but not between age and weight. Conclusion: This article presents data for a normal range of straw drinking speeds in a healthy adult population. It can be used in the assessment and monitoring of straw drinking in acquired disorders of swallowing