7,007 research outputs found

    The Use of AIS Data for Identifying and Mapping Calcareous Soils in Western Nebraska

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    The identification of calcareous soils, through unique spectral responses of the vegetation to the chemical nature of calcareous soils, can improve the accuracy of delineating the boundaries of soil mapping units over conventional field techniques. The objective of this experiment is to evaluate the use of the Airborne Imaging Spectrometer (AIS) in the identification and delineation of calcareous soils in the western Sandhills of Nebraska. Based upon statistical differences found in separating the spectral curves below 1.3 microns, calcareous and non-calcareous soils may be identified by differences in species of vegetation. Additional work is needed to identify biogeochemical differences between the two soils

    The quiescent progenitors of four Type II-P/L supernovae

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    We present Large Binocular Telescope difference imaging data for the final years of four Type II-P/L supernovae progenitors. For all four, we find no significant evidence for stochastic or steady variability in the U, B, V, or R-bands. Our limits constrain variability to no more than roughly 5-10% of the expected R-band luminosities of the progenitors. These limits are comparable to the observed variability of red supergiants in the Magellanic Clouds. Based on these four events, the probability of a Type II-P/L progenitor having an extended outburst after Oxygen ignition is <37% at 90% confidence. Our observations cannot exclude short outbursts in which the progenitor returns to within ~10% of its quiescent flux on the time scale of months with no dust formation.Comment: 9 pages, 8 figures, 1 table. Accepted to MNRA

    Pseudogap in high-temperature superconductors from realistic Fr\"ohlich and Coulomb interactions

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    It has been recently shown that the competition between unscreened Coulomb and Fr\"{o}hlich electron-phonon interactions can be described in terms of a short-range spin exchange JpJ_p and an effective on-site interaction U~\tilde{U} in the framework of the polaronic tt-JpJ_p-U~\tilde{U} model. This model, that provides an explanation for high temperature superconductivity in terms of Bose-Einstein condensation (BEC) of small and light bipolarons, is now studied as a charged Bose-Fermi mixture. Within this approximation, we show that a gap between bipolaron and unpaired polaron bands results in a strong suppression of low-temperature spin susceptibility, specific heat and tunneling conductance, signaling the presence of normal state pseudogap without any assumptions on preexisting orders or broken symmetries in the normal state of the model.Comment: 5 pages, 5 figure

    Impact of Mobility on MIMO Green Wireless Systems

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    This paper studies the impact of mobility on the power consumption of wireless networks. With increasing mobility, we show that the network should dedicate a non negligible fraction of the useful rate to estimate the different degrees of freedom. In order to keep the rate constant, we quantify the increase of power required for several cases of interest. In the case of a point to point MIMO link, we calculate the minimum transmit power required for a target rate and outage probability as a function of the coherence time and the number of antennas. Interestingly, the results show that there is an optimal number of antennas to be used for a given coherence time and power consumption. This provides a lower bound limit on the minimum power required for maintaining a green network.Comment: Accepted for EUSIPCO conference. 5 page

    Cross-layer distributed power control: A repeated games formulation to improve the sum energy-efficiency

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    The main objective of this work is to improve the energy-efficiency (EE) of a multiple access channel (MAC) system, through power control, in a distributed manner. In contrast with many existing works on energy-efficient power control, which ignore the possible presence of a queue at the transmitter, we consider a new generalized cross-layer EE metric. This approach is relevant when the transmitters have a non-zero energy cost even when the radiated power is zero and takes into account the presence of a finite packet buffer and packet arrival at the transmitter. As the Nash equilibrium (NE) is an energy-inefficient solution, the present work aims at overcoming this deficit by improving the global energy-efficiency. Indeed, as the considered system has multiple agencies each with their own interest, the performance metric reflecting the individual interest of each decision maker is the global energy-efficiency defined then as the sum over individual energy-efficiencies. Repeated games (RG) are investigated through the study of two dynamic games (finite RG and discounted RG), whose equilibrium is defined when introducing a new operating point (OP), Pareto-dominating the NE and relying only on individual channel state information (CSI). Accordingly, closed-form expressions of the minimum number of stages of the game for finite RG (FRG) and the maximum discount factor of the discounted RG (DRG) were established. The cross-layer model in the RG formulation leads to achieving a shorter minimum number of stages in the FRG even for higher number of users. In addition, the social welfare (sum of utilities) in the DRG decreases slightly with the cross-layer model when the number of users increases while it is reduced considerably with the Goodman model. Finally, we show that in real systems with random packet arrivals, the cross-layer power control algorithm outperforms the Goodman algorithm.Comment: 36 pages, single column draft forma

    An Analysis of Remittance Tendencies of Philippine Migrant Workers

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    In developing countries, remittances play a key role as a source of external finance. Remittances are a form of aid that migrant workers send back to their families, located in their home countries, in order to support the needs of the household. In about 25% of developing countries, remittances are larger than public and private capital flows combined (International Monetary Fund, 2009). In 2008, the Philippines economy was the 47th largest economy in the world with a GDP of $322 billion dollars (Asian Development Bank, Fact Sheet). Remittances accounted for over 10% of the Philippine economy, making the Philippines one of the world’s highest remittance receiving countries. Using a probit model and an OLS regression model focusing on the Philippines in 2003, this paper will focus on exploring what variables influence the decision to send a household member away for work, what factors contribute to whether or not a household receives a remittance and if they do, how these same characteristics affect the value of the remittance

    THE ROLE OF THE COMMUNITY CAPITAL FRAMEWORK AND CHRISTIAN FAITH-BASED COMMUNITY DEVELOPMENT ORGANIZATIONS IN KENTUCKY

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    The purpose of this study is to investigate the work of Christian faith-based organizations (FBO) doing community development work in Kentucky and to learn about how they might be using community development concepts and system approaches as articulated in the Community Capitals Framework (CCF) and to critically examine those findings. The CCF is comprised of seven capitals including Natural, Cultural, Human, Social, Political, Financial, and Built. Emery and Flora (2006) assert that the “CCF offers a way to analyze community and economic development efforts from a systems perspective by identifying the assets in each capital (stock), the types of capital investment (flow), the interaction among the capitals, and the resulting impacts across capitals” (p.20). This study will explore and test how faith-based organizations are deliberately incorporating a systems approach through the application of the seven capitals in their planning; how they are emphasizing or de-emphasizing certain kinds of capital; and, how a particular-capital might be influencing people and communities. While many FBO’s are using some community development approaches in Kentucky, there is limited understanding about how they may or may not be using systems theory as manifested in the community capitals context. This study contains a critical analysis that might be helpful for government and private sector policy development. It provides insights about the applicability and limitations of the CCF in doing faith-based community development. I hope to use the knowledge gained from this study to further explore faith-based community development in my home country, Liberia

    Effect of probiotic Bacillus spp.-supplemented feed on the growth, length-weight relationship, and condition factor of Nile tilapia (Oreochromis niloticus)

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    This study was carried out to evaluate the effect of two probiotic Bacillus spp. (RM10 and BFAR9) on the growth, length-weight relationship (LWR), and condition factor (k) of Nile tilapia (Oreochromis niloticus). For this, one hundred thirty-five fingerlings (1.12±0.08 g weight and 1.26±0.15 cm length) were divided into three groups (Control, RM10, and BFAR9) and distributed into nine circular concrete tanks. The fish were fed with commercial (control) and Bacillus spp. supplemented diets at 5% of body weight for 56 days. The results of the study revealed better (P&lt;0.05) growth concerning average body weight (ABW - 17.12±0.71g), specific growth rate (SGR - 4.89±0.22 g·day-1), absolute growth (AG - 16.02±0.78 g), and feed conversion ratio (FCR - 1.31±0.09) in the group fed with Bacillus sp. RM10 as compared to the control (ABW- 13.25±2.34g; SGR - 4.41±0.17g·day-1; AG - 12.13±2.25g; FCR - 1.62±0.11). The LWR in all experimental treatments showed a significant correlation (P&lt;0.05) with an R2 value of 0.988, 0.966, and 0.979 for Control, RM10, and BFAR9, respectively. The k value revealed that all treatments are in good condition as k value is greater than 1 (1.913, 2.038, and 1.896 for control, RM10, and BFAR9 respectively). The result of the current study revealed that application of Bacillus sp. RM10 improves the growth and feed utilization in Nile tilapia

    X-56A Structural Dynamics Ground Testing Overview and Lessons Learned

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    The X-56A Multi-Utility Technology Testbed (MUTT) is a subscale, fixed-wing aircraft designed for high-risk aeroelastic flight demonstration and research. Structural dynamics ground testing for model validation was especially important for this vehicle because the structural model was directly used in the development of a flight control system with active flutter suppression capabilities. Structural dynamics ground tests of the X-56A MUTT with coupled rigid-body and structural modes provided a unique set of challenges. An overview of the ground vibration test (GVT) and moment of inertia (MOI) test setup and execution is presented. The series of GVTs included the wing by itself attached to a strongback and complete vehicle at two mass conditions: empty and full fuel. Two boundary conditions for the complete-vehicle test were studied: on landing gear and suspended free-free. Pitch MOI tests were performed using a compound pendulum method and repeated with two different pendulum lengths for independent verification. The original soft-support test configuration for the GVT used multiple bungees, resulting in unforeseen coupling interactions between the soft-support bungees and the vehicle structural modes. To resolve this problem, the soft-support test setup underwent multiple iterations. The various GVT configurations and boundary-condition modifications are highlighted and explained. Lessons learned are captured for future consideration when performing structural dynamics testing with similar vehicles
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