AGRICULTURAL, FOOD AND HUMAN RESOURCE POLICIES: IMPLICATIONS FOR RURAL AFRICAN-AMERICANS

Agricultural and Food Policy,

State-Dependent Variability of Neuronal Responses to Transcranial Magnetic Stimulation of the Visual Cortex

SummaryElectrical brain stimulation is a promising tool for both experimental and clinical applications. However, the effects of stimulation on neuronal activity are highly variable and poorly understood. To investigate the basis of this variability, we performed extracellular recordings in the visual cortex following application of transcranial magnetic stimulation (TMS). Our measurements of spiking and local field potential activity exhibit two types of response patterns which are characterized by the presence or absence of spontaneous discharge following stimulation. This variability can be partially explained by state-dependent effects, in which higher pre-TMS activity predicts larger post-TMS responses. These results reveal the possibility that variability in the neural response to TMS can be exploited to optimize the effects of stimulation. It is conceivable that this feature could be utilized in real time during the treatment of clinical disorders

Effects of vibration on inertial wind-tunnel model attitude measurement devices

Results of an experimental study of a wind tunnel model inertial angle-of-attack sensor response to a simulated dynamic environment are presented. The inertial device cannot distinguish between the gravity vector and the centrifugal accelerations associated with wind tunnel model vibration, this situation results in a model attitude measurement bias error. Significant bias error in model attitude measurement was found for the model system tested. The model attitude bias error was found to be vibration mode and amplitude dependent. A first order correction model was developed and used for estimating attitude measurement bias error due to dynamic motion. A method for correcting the output of the model attitude inertial sensor in the presence of model dynamics during on-line wind tunnel operation is proposed

Towards precision particle background estimation for future X-ray missions: correlated variability between Chandra ACIS and AMS

A science goal of many future X-ray observatories is mapping the cosmic web through deep exposures of faint diffuse sources. Such observations require low background and the best possible knowledge of the remaining unrejected background. The dominant contribution to the background above 1-2 keV is from Galactic Cosmic Ray protons. Their flux and spectrum are modulated by the solar cycle but also by solar activity on shorter timescales. Understanding this variability may prove crucial to reducing background uncertainty for ESA's Athena X-ray Observatory and other missions with large collecting area. We examine of the variability of the particle background as measured by ACIS on the Chandra X-ray Observatory and compare that variability to that measured by the Alpha Magnetic Spectrometer (AMS), a precision particle detector on the ISS. We show that cosmic ray proton variability measured by AMS is well matched to the ACIS background and can be used to estimate proton energies responsible for the background. We discuss how this can inform future missions.Comment: 11 pages, 8 figures, submitted to Proceedings of SPIE Astronomical Telescopes + Instrumentation 202

Using Satellite Aerosol Retrievals to Monitor Surface Particulate Air Quality

The MODIS and MISR aerosol products were designed nearly two decades ago for the purpose of climate applications. Since launch of Terra in 1999, these two sensors have provided global, quantitative information about column-integrated aerosol properties, including aerosol optical depth (AOD) and relative aerosol type parameters (such as Angstrom exponent). Although primarily designed for climate, the air quality (AQ) community quickly recognized that passive satellite products could be used for particulate air quality monitoring and forecasting. However, AOD and particulate matter (PM) concentrations have different units, and represent aerosol conditions in different layers of the atmosphere. Also, due to low visible contrast over brighter surface conditions, satellite-derived aerosol retrievals tend to have larger uncertainty in urban or populated regions. Nonetheless, the AQ community has made significant progress in relating column-integrated AOD at ambient relative humidity (RH) to surface PM concentrations at dried RH. Knowledge of aerosol optical and microphysical properties, ambient meteorological conditions, and especially vertical profile, are critical for physically relating AOD and PM. To make urban-scale maps of PM, we also must account for spatial variability. Since surface PM may vary on a finer spatial scale than the resolution of standard MODIS (10 km) and MISR (17km) products, we test higher-resolution versions of MODIS (3km) and MISR (1km research mode) retrievals. The recent (July 2011) DISCOVER-AQ campaign in the mid-Atlantic offers a comprehensive network of sun photometers (DRAGON) and other data that we use for validating the higher resolution satellite data. In the future, we expect that the wealth of aircraft and ground-based measurements, collected during DISCOVER-AQ, will help us quantitatively link remote sensed and ground-based measurements in the urban region

Theory of One-Channel vs. Multi-Channel Kondo Effects for Ce3+^{3+} Impurities

We introduce a model for Ce$^{3+}$ impurities in cubic metals which exhibits competition between the Fermi-liquid fixed point of the single channel Kondo model and the non-Fermi-liquid fixed point of the two- and three-channel Kondo models. Using the non-crossing approximation and scaling theory, we find: (i) A possible three-channel Kondo effect between the one- and two-channel regimes in parameter space. (ii) The sign of the thermopower is a fixed point diagnostic. (iii) Our results will likely survive the introduction of additional $f^2$ and conduction states. We apply this model to interpret the non-Fermi liquid alloy La$_{1-x}$Ce$_x$Cu$_{2.2}$Si$_2$.Comment: 13 pages, Revtex, To appear in Phys. Rev. Let

Convective plumes and the scarcity of Titan's clouds

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94936/1/grl19061.pd