Links between topography, wind, deflation, lakes and dust: The case of the Bodélé Depression, Chad

The Bodélé Depression, Chad is the planet's largest single source of dust. Deflation from the Bodélé could be seen as a simple coincidence of two key prerequisites: strong surface winds and a large source of suitable sediment. But here we hypothesise that long term links between topography, winds, deflation and dust ensure the maintenance of the dust source such that these two apparently coincidental key ingredients are connected by land-atmosphere processes with topography acting as the overall controlling agent. We use a variety of observational and numerical techniques, including a regional climate model, to show that: 1) contemporary deflation from the Bodélé is delineated by topography and a surface wind stress maximum; 2) the Tibesti and Ennedi mountains play a key role in the generation of the erosive winds in the form of the Bodélé Low Level Jet (LLJ); 3) enhanced deflation from a stronger Bodélé LLJ during drier phases, for example, the Last Glacial Maximum, was probably sufficient to create the shallow lake in which diatoms lived during wetter phases, such as the Holocene pluvial. Winds may therefore have helped to create the depression in which erodible diatom material accumulated. Instead of a simple coincidence of nature, dust from the world's largest source may result from the operation of long term processes on paleo timescales which have led to ideal conditions for dust generation in the world's largest dust source. Similar processes plausibly operate in other dust hotspots in topographic depressions

Two-qubit parametric amplifier: large amplification of weak signals

Using numerical simulations, we show that two coupled qubits can amplify a weak signal about hundredfold. This can be achieved if the two qubits are biased simultaneously by this weak signal and a strong pump signal, both of which having frequencies close to the inter-level transitions in the system. The weak signal strongly affects the spectrum generated by the strong pumping drive by producing and controlling mixed harmonics with amplitudes of the order of the main harmonic of the strong drive. We show that the amplification is robust with respect to noise, with an intensity of the order of the weak signal. When deviating from the optimal regime (corresponding to strong qubit coupling and a weak-signal frequency equal to the inter-level transition frequency) the proposed amplifier becomes less efficient, but it can still considerably enhance a weak signal (by several tens). We therefore propose to use coupled qubits as a combined parametric amplifier and frequency shifter.Comment: 6 figure

Carbonate-Clastic Synthems of the Middle Beekmantown Group in the Central and Southern Champlain Valley

Guidebook for field trips in Vermont: New England Intercollegiate Geological Conference, 79th annual meeting, October 16, 17 and 18, 1987: Trips C-4. Irregular pagination

Stimulants for enhancement purposes: perceptions attitudes, usage among university students

Objective: Determine perceptions, attitudes, and usage of non medical prescription stimulants among students at a Midwestern technology focused university. Participants: 241 university students. Methods: Data was collected in March 2015 through an anonymous web survey. A logistic regression model evaluated predictors. T-test was used to evaluate differences between groups. Results: 9.5% had used prescription stimulants without a valid prescription. Primary motives were academic preparation (78%) and recreation (61%). Nicotine use (OR = 8.99, CI 2.40, 33.77, p \u3c .01), peer\u27s suggestion (OR = 6.95, C12.21, 21.84, p \u3c .01), and positive attitudes toward use (OR = 1.99, CI 1.06, 3.72, p \u3c .05) increased odds of nonmedical use. Users and non-users differed in estimations of nonmedical use within peers (t (239) = 3.17, p \u3c .01) and in their field (t (239) = 3.22, p \u3c .01). Conclusions: Administrators should acknowledge student use and develop strategies to address it

Rethinking Female Urinary Devices for the US Army

As women assume more combat roles in the US military and continue to operate in austere environments with varied mission sets, the Department of Defense must rethink its approach to equipment and uniform development to accommodate female anatomical differences. This article analyzes the results of a study conducted during the Sandhurst Military Skills Competition at the United States Military Academy to determine the effectiveness of commercial off-the-shelf products the Army has adopted to aid female urination—products used by competition participants that may not be the best or healthiest options for women

A bound on 6D N=1 supergravities

We prove that there are only finitely many distinct semi-simple gauge groups and matter representations possible in consistent 6D chiral (1,0) supergravity theories with one tensor multiplet. The proof relies only on features of the low-energy theory; the consistency conditions we impose are that anomalies should be cancelled by the Green-Schwarz mechanism, and that the kinetic terms for all fields should be positive in some region of moduli space. This result does not apply to the case of the non-chiral (1,1) supergravities, which are not constrained by anomaly cancellation.Comment: 23 pages, no figures; two paragraphs added to the proof in Appendix A covering the SU(2) and SU(3) case, other minor correction

Renormalized Equilibria of a Schloegl Model Lattice Gas

A lattice gas model for Schloegl's second chemical reaction is described and analyzed. Because the lattice gas does not obey a semi-detailed-balance condition, the equilibria are non-Gibbsian. In spite of this, a self-consistent set of equations for the exact homogeneous equilibria are described, using a generalized cluster-expansion scheme. These equations are solved in the two-particle BBGKY approximation, and the results are compared to numerical experiment. It is found that this approximation describes the equilibria far more accurately than the Boltzmann approximation. It is also found, however, that spurious solutions to the equilibrium equations appear which can only be removed by including effects due to three-particle correlations.Comment: 21 pages, REVTe