Parametric Amplification of Nonlinear Response of Single Crystal Niobium

Giant enhancement of the nonlinear response of a single crystal Nb sample, placed in {\it a pumping ac magnetic field}, has been observed experimentally. The experimentally observed amplitude of the output signal is about three orders of magnitude higher than that seen without parametric pumping. The theoretical analysis based on the extended double well potential model provides a qualitative explanation of the experimental results as well as new predictions of two bifurcations for specific values of the pumping signal.Comment: 6 pages, 10 figure

Composite Ground Modification System: Vibroreplacement and Dynamic Compaction, Salt Lake County Detention Center, Utah

The site for a new Adult Detention Center currently under construction in Salt Lake City, Utah, is underlain by loose sands and soft clayey lake deposits. Due to bearing capacity, static settlement, and liquefaction concerns, a hybrid ground improvement program consisting of both dynamic compaction and vibroreplacement was implemented. Stone columns were concentrated under spread and wall footings; dynamic compaction was performed over the whole site. A comprehensive quality assurance/ quality control program was executed, with a significant number of cone penetration tests, standard penetration tests, 10 plate load tests, and deceleration readings taken with an accelerometer mounted on the dynamic compaction weight. This large body of data enabled the authors to assess the effectiveness of the ground improvement program, as well as analyze the results of the experimental deceleration readings

Steady Hall Magnetohydrodynamics Near a X-type Magnetic Neutral Line

Hall magnetohydrodynamics (MHD) properties near a two-dimensional (2D) X-type magnetic neutral line in the steady state are considered via heuristic and rigorous developments. Upon considering the steady-state as the asymptotic limit of the corresponding \textit{time-dependent} problem and using a rigorous development, Hall effects are shown to be able to sustain the hyperbolicity of the magnetic field (and hence a more open X-point configuration) near the neutral line in the steady state. The heuristic development misses this subtle connection of the steady state with the corresponding \textit{time-dependent} problem and predicts only an elongated current-sheet configuration (as in resistive MHD). However, the heuristic development turns out to be useful in providing insight into the lack of dependence of the reconnection rate on the mechanism breaking the frozen-in condition of the magnetic field lines. The latter result can be understood in terms of the ability of the ions and electrons to transport equal amounts of magnetic flux per unit time out of the reconnection region.Comment: 1-10 page

Characterization of the stretched exponential trap-time distributions in one-dimensional coupled map lattices

Stretched exponential distributions and relaxation responses are encountered in a wide range of physical systems such as glasses, polymers and spin glasses. As found recently, this type of behavior occurs also for the distribution function of certain trap time in a number of coupled dynamical systems. We analyze a one-dimensional mathematical model of coupled chaotic oscillators which reproduces an experimental set-up of coupled diode-resonators and identify the necessary ingredients for stretched exponential distributions.Comment: 8 pages, 8 figure

Modelling the Inorganic Bromine Partitioning in the Tropical Tropopause over the Pacific Ocean

The stratospheric inorganic bromine burden (Bry) arising from the degradation of brominated very short-lived organic substances (VSL org ), and its partitioning between reactive and reservoir species, is needed for a comprehensive assessment of the ozone depletion potential of brominated trace gases. Here we present modelled inorganic bromine abundances over the Pacific tropical tropopause based on aircraft observations of VSL org of two campaigns of the Airborne Tropical TRopopause EXperiment (ATTREX 2013 carried out over eastern Pacific and ATTREX 2014 carried out over the western Pacific) and chemistry-climate simulations (along ATTREX flight tracks) using the specific meteorology prevailing. Using the Community Atmosphere Model with Chemistry (CAM-Chem), we model that BrO and Br are the daytime dominant species. Integrated across all ATTREX flights BrO represents ~ 43 % and 48 % of daytime Bry abundance at 17 km over the Western and Eastern Pacific, respectively. The results also show zones where Br/BrO >1 depending on the solar zenith angle (SZA), ozone concentration and temperature. On the other hand, BrCl and BrONO 2 were found to be the dominant night-time species with ~ 61% and 56 % of abundance at 17 km over the Western and Eastern Pacific, respectively. The western-to-eastern differences in the partitioning of inorganic bromine are explained by different abundances of ozone (O3), nitrogen dioxide (NO2) , and total inorganic chlorine (Cly).Fil: Navarro, María A.. University of Miami; Estados UnidosFil: Saiz-lopez, Alfonso. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; EspañaFil: Cuevas, Carlos Alberto. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; EspañaFil: Fernandez, Rafael Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentina. Universidad Tecnologica Nacional. Facultad Regional Mendoza. Secretaría de Ciencia, Tecnología y Postgrado; ArgentinaFil: Atlas, Elliot. University of Miami; Estados UnidosFil: Rodriguez Lloeveras, Xavier. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; EspañaFil: Kinnison, Douglas E.. National Center For Atmospheric Research. Amospheric Chemistry División; Estados UnidosFil: Lamarque, Jean Francois. National Center For Atmospheric Research. Amospheric Chemistry División; Estados UnidosFil: Tilmes, Simone. National Center For Atmospheric Research. Amospheric Chemistry División; Estados UnidosFil: Thornberry, Troy. State University of Colorado at Boulder; Estados Unidos. Earth System Research Laboratory; Estados UnidosFil: Rollins, Andrew. State University of Colorado at Boulder; Estados Unidos. Earth System Research Laboratory; Estados UnidosFil: Elkins, James W.. Earth System Research Laboratory; Estados UnidosFil: Hintsa, Eric J.. State University of Colorado at Boulder; Estados Unidos. Earth System Research Laboratory; Estados UnidosFil: Moore, Fred L.. State University of Colorado at Boulder; Estados Unidos. Earth System Research Laboratory; Estados Unido

The 2013 Cybersecurity Executive Order: Overview and Considerations for Congress

This report provides background information regarding the threats and consequences of cybersecurity. The federal legislative framework for cybersecurity is complex, with more than 50 statutes addressing various aspects of it either directly or indirectly

A Simulation Model of Sustained-Yield Harvest for Northern Bobwhite in South Texas

Recommended sustainable harvest rates for northern bobwhite (Colinus virginianus) vary greatly and range from 25% to 70% of the prehunt population. Because northern bobwhite populations have declined across their geographic range, determining sustainable harvest levels is critical for effective management. Our objectives were to use simulation modeling to identify sustainable rates of bobwhite harvest, probability of population persistence, and minimum viable population estimates. We also conducted a sensitivity analysis to evaluate the impacts of harvest on northern bobwhite populations in Texas, USA. We constructed a simulation model using Program STELLA 9.0 for a hypothetical northern bobwhite population on 800 ha in the South Texas Plains USA and modeled population dynamics to 100 years over a range of harvest rates (0–40%). A 20% harvest rate produced the greatest average yields (mean ± standard error = 231 ± 10 bobwhites harvested/year). Given a quasi-extinction criterion of ≤40 bobwhites (≤0.05 bobwhite/ha), a 30% harvest rate resulted in a high probability of quasi-extinction (PE = 0.75) within 47.8 ± 2.3 years. A 40% harvest rate was not sustainable (PE = 1.0), with quasi-extinction occurring within 15.5 ± 2.6 years. Harvesting northern bobwhite populations in the South Texas Plains at rates of 20−25% of the prehunt population should maximize long-term harvest while minimizing the probability of population extinction. Spring densities of 0.60−0.80 bobwhite/ha may represent minimum viable spring densities for northern bobwhite populations in the South Texas Plains as these are the densities associated with sustainable 20-25% harvest rates. Harvest rates \u3e30% are likely to be excessive with respect to long-term population persistence for northern bobwhite populations in the South Texas Plains

Field Application of Sustained-Yield Harvest Management for Northern Bobwhite in Texas

Sustained-yield harvest (SYH) is considered a potentially viable strategy for managing harvest of northern bobwhites (Colinus virginianus). However, application of SYH has not been evaluated for northern bobwhites. We evaluated the application of using SYH as a harvest management strategy for bobwhite during the 2007 2008 and 2008 2009 hunting seasons in 2 ecoregions of Texas (Rolling Plains, South Texas Plains). We collected field data at 3 study sites/ecoregion (900 1,900 ha each; 2 hunted sites and 1 control) to estimate 4 demographic parameters (fall and spring density, overwinter survival in the absence of hunting, and harvest rate). We used these data to parameterize the additive harvest model for bobwhites and compare predictions of spring abundance of the model with field estimates. The additive harvest model, compared to field estimates, consistently underestimated spring population density (mean 6 SE) by 55.7 6 17.8% (2007 2008) and 34.1 6 4.9% (2008 2009) in the Rolling Plains, and by 26.4 6 25.3% (2007 2008) and 49.1 6 2.1% (2008 2009) in the South Texas Plains. Implementing SYH in the field, despite its potential benefits, will be challenging given the need for reliable estimates of 3 key population parameters (fall and spring density, and natural mortality in the absence of hunting) and the high variation often associated with them. Conservative harvest prescriptions based on the lower 95% CIs of fall density estimates may permit sustainable harvest despite variation in density estimates

Organic nitrate and secondary organic aerosol yield from NO3 oxidation of ß-pinene evaluated using a gas-phase kinetics/aerosol partitioning model

The yields of organic nitrates and of secondary organic aerosol (SOA) particle formation were measured for the reaction NO3+beta-pinene under dry and humid conditions in the atmosphere simulation chamber SAPHIR at Research Center Julich. These experiments were conducted at low concentrations of NO3 (NO3+N2O5 < 10 ppb) and beta-pinene (peak similar to 15 ppb), with no seed aerosol. SOA formation was observed to be prompt and substantial (similar to 50% mass yield under both dry conditions and at 60% RH), and highly correlated with organic nitrate formation. The observed gas/aerosol partitioning of organic nitrates can be simulated using an absorptive partitioning model to derive an estimated vapor pressure of the condensing nitrate species of p(vap) similar to 5x10(-6) Torr (6.67x10(-4) Pa), which constrains speculation about the oxidation mechanism and chemical identity of the organic nitrate. Once formed the SOA in this system continues to evolve, resulting in measurable aerosol volume decrease with time. The observations of high aerosol yield from NOx-dependent oxidation of monoterpenes provide an example of a significant anthropogenic source of SOA from biogenic hydrocarbon precursors. Estimates of the NO3+beta-pinene SOA source strength for California and the globe indicate that NO3 reactions with monoterpenes are likely an important source (0.5-8% of the global total) of organic aerosol on regional and global scales