Two-fluid temperature-dependent relativistic waves in magnetized streaming pair plasmas

A relativistic two-fluid temperature-dependent approach for a streaming magnetized pair plasma is considered. Such a scenario corresponds to secondary plasmas created at the polar caps of pulsar magnetospheres. In the model the generalized vorticity rather than the magnetic field is frozen into the fluid. For parallel propagation four transverse modes are found. Two are electromagnetic plasma modes which at high temperature become light waves. The remaining two are Alfveacutenic modes split into a fast and slow mode. The slow mode is cyclotron two-stream unstable at large wavelengths and is always subluminous. We find that the instability cannot be suppressed by temperature effects in the limit of large (finite) magnetic field. The fast Alfveacuten mode can be superluminous only at large wavelengths, however it is always subluminous at high temperatures. In this incompressible approximation only the ordinary mode is present for perpendicular propagation. For oblique propagation the dispersion relation is studied for finite and large strong magnetic fields and the results are qualitatively described.Institute for Fusion Studie

Deep Studies of the Resolved Stellar Populations in the Outskirts of M31

We discuss the first results from ongoing studies of the resolved stellar populations in the outskirts of our nearest large neighbour, M31. Deep HST/WFPC2 archival observations are used to construct colour-magnitude-diagrams which reach well below the horizontal branch at selected locations in the outer disk and halo, while a panoramic ground-based imaging survey maps spatial density variations through resolved star counts to a projected radius of ~50 kpc.Comment: 4 pages, to appear in proc of "New Quests in Stellar Astrophysics: The Link Between Stars and Cosmology", eds. M. Chavez, A. Bressan, A. Buzzoni, D. Mayy

Optimal Configurations for Aerosol Monitoring with Multi-Rotor Small Unmanned Aerial Systems

Applicability of aerosol sampling on multi-rotor unmanned aerial systems (UAS) platform was investigated. Multi-rotor UAS have impacts of wind speed, turbulence, and orientation possibly contributing to sampling bias. The SKC IMPACT sampler, Tecora C.A.Th.I.A., and modified three-dimensionally printed Universal Inlet for Airborne-Particle Size-Selective Sampling were selected based on particle size-selectivity and operational independence to wind. Airflow visualizations concluded that below UAS fuselage was optimal sampler placement. Tests were conducted with Arizona Road Dust in a still-air chamber, and aerosolized sugar in a wind tunnel. Inlet mounting was evaluated in, upright, upside-down, and horizontal orientations. Horizontal orientations of all inlets resulted in negative sampling bias compared to upright/upside-down positions. Sampling bias of inlets mounted on the UAS were compared with and without motor employment. In wind tunnel tests, the IMPACT sampler averaged lowest count concentration bias while the 3D printed inlet resulted in the largest percent difference. Results suggests, UAS turbulence and low wind speed produced negative sampling bias. The 3D printed inlet was designed with Stokes’ scaling factor, and compared with the well-characterized IMPACT sampler. Three-dimensional printing bolstered a cost-effective and fast method of inlet design and construction. Iterative designs can optimize aerosol inlets suitable for mounting on multi-rotor UAS

Effects of landscape configuration metrics on American barn owl nest box occupancy and hunting

Harnessing ecosystem services, broadly defined as the benefits nature gives to people, is one approach to minimize the widespread negative impacts of agriculture on wildlife and biodiversity conservation. Conservation biological control is one such service that aims to use natural enemies to reduce crops losses from pests without the use of harmful pesticides, including rodenticides. In Napa Valley, California, human-made nest boxes are deployed on wine grape vineyards to attract barn owls (Tyto furcata) that depredate and remove thousands of rodent pests throughout the nesting season. However, the provisioning of this ecosystem service depends on whether a box is occupied and where on the landscape the owls are hunting. In this thesis, I used predictive occupancy models to show that barn owls prefer to occupy nest boxes surrounded by high proportions of grassland, and they prefer to hunt near their nest boxes, near oak savanna habitat, and in areas with a low habitat aggregation. A map of these models combined shows the hunting pressure by the owls in the study site’s vineyards. By mapping the provisioning of ecosystem services, landowners can be better informed on how land cover and nest box deployment affect the provisioning of rodent pest removal in their vineyard agroecosystems