Collective shuttling of attracting particles in asymmetric narrow channels

The rectification of a single file of attracting particles subjected to a low frequency ac drive is proposed as a working mechanism for particle shuttling in an asymmetric narrow channel. Increasing the particle attraction results in the file condensing, as signalled by the dramatic enhancement of the net particle current. Magnitude and direction of the current become extremely sensitive to the actual size of the condensate, which can then be made to shuttle between two docking stations, transporting particles in one direction, with an efficiency much larger than conventional diffusive models predict

Peer Counseling for Student Success in University Flight Education: A Case Example

In response to attrition rates, the Department of Aeronautical Science in the College of Aviation at Embry-Riddle Aeronautical University in Prescott, AZ, analyzed how best to identify and assist students who were struggling with their flight training. In order to maximize student retention, students at risk must be identified early, prior to training failure or financial distress. The assessment of these findings of the flight program and the attrition rates resulted in a “Student Success Initiative” (SSI) being established that would identify students approaching ‘at-risk’ points in flight training, both fixed-wing and helicopter. These students would be assessed and ultimately required to attend an intervention session with support staff in coordination with his/her academic faculty advisor and/or flight staff. This meeting concludes with a contract of expectations signed by the student that includes a plan of action and specific timelines. One critical challenge in the implementation of the SSI program was to find an effective way to provide support for students in the program. The answer was to develop a program manned by “peer counselors” to provide tutoring and other support resources for students in need of help

Maximizing Student Achievements: Mastering Aviation English

Flight training delays and corresponding increased costs appear to be widespread among universities with aviation programs. Students in these programs have to juggle demanding academics and flight training. Additionally, international students, for whom English is not their primary language, have the added disadvantage of learning complex aviation concepts in English. In order to maximize retention in collegiate flight programs, an experimental aviation English course has been designed to help frontload aviation vocabulary and take a proactive approach to teaching language skills that are essential in flight training

Field Theory of the Random Flux Model

The long-range properties of the random flux model (lattice fermions hopping under the influence of maximally random link disorder) are shown to be described by a supersymmetric field theory of non-linear sigma model type, where the group GL(n|n) is the global invariant manifold. An extension to non-abelian generalizations of this model identifies connections to lattice QCD, Dirac fermions in a random gauge potential, and stochastic non-Hermitian operators.Comment: 4 pages, 1 eps figur

Effect of soil fertilization on the incidence of berry shrivel and the quality of resulting wine

Berry shrivel is becoming an increasing concern for winegrowers all over the world. Until today, no single factor causing this physiological disorder has been determined. Studies concerning berry shrivel conducted in Austria have shown that an unbalanced ratio of K and Mg in the soil is a likely factor contributing to the disorder. The aims of the present study were to establish a better understanding of the causes and consequences of berry shrivel and observe the effects of K and Mg fertilization via the soil on the incidence of berry shrivel, the mineral composition of affected berries and the resulting wine quality. A two-year fertilization trial was conducted on two sites located within southern Germany with the varieties 'Zweigelt' and 'Pinot Blanc'. Different amounts of K and Mg were applied each year at both locations in order to generate different ratios of K and Mg in the soil. Before harvest, the incidences of berry shrivel of the different treatments were determined. In addition, macronutrients including K, Mg and Ca that were translocated in healthy berries and berries affected by berry shrivel were determined at harvest. To compare the quality of wine influenced by berry shrivel, different wines were produced consisting of shrivelled berries, berries affected by bunch stem necrosis and healthy berries. In the soil fertilization trials, no significant differences in the incidences of berry shrivel were observed in relation to the soil fertilization. Major differences were found in the wine qualities of the different wines. Wines produced from healthy berries were always rated as the best wines, whereas wines produced from shrivelled berries were always rated as the lowest quality. The low quality parameters found in the must did not improve in the wine making process. Wines produced from berries affected by bunch stem necrosis were rated better than berry-shrivel-wines, however, rated less than the wine produced from healthy berries. The determinations of macronutrients’ level in the berries showed significant differences regarding the concentration of Ca. In the variety 'Zweigelt' in 2009, an average of 36 mg∙L-1 of Ca were found in healthy berries and 107 mg∙L-1 in berries affected by berry shrivel. In 'Pinot Blanc' in 2010, the average of Ca in healthy berries was 46 mg∙L-1 and 70 mg∙L-1 in berries affected by berry shrivel. No significant differences were found for K and Mg in the berries.

Localization in non-chiral network models for two-dimensional disordered wave mechanical systems

Scattering theoretical network models for general coherent wave mechanical systems with quenched disorder are investigated. We focus on universality classes for two dimensional systems with no preferred orientation: Systems of spinless waves undergoing scattering events with broken or unbroken time reversal symmetry and systems of spin 1/2 waves with time reversal symmetric scattering. The phase diagram in the parameter space of scattering strengths is determined. The model breaking time reversal symmetry contains the critical point of quantum Hall systems but, like the model with unbroken time reversal symmetry, only one attractive fixed point, namely that of strong localization. Multifractal exponents and quasi-one-dimensional localization lengths are calculated numerically and found to be related by conformal invariance. Furthermore, they agree quantitatively with theoretical predictions. For non-vanishing spin scattering strength the spin 1/2 systems show localization-delocalization transitions.Comment: 4 pages, REVTeX, 4 figures (postscript

Two Electrons in a Quantum Dot: A Unified Approach

Low-lying energy levels of two interacting electrons confined in a two-dimensional parabolic quantum dot in the presence of an external magnetic field have been revised within the frame of a novel model. The present formalism, which gives closed algebraic solutions for the specific values of magnetic field and spatial confinement length, enables us to see explicitly individual effects of the electron correlation.Comment: 14 page

Critical regime of two dimensional Ando model: relation between critical conductance and fractal dimension of electronic eigenstates

The critical two-terminal conductance $g_c$ and the spatial fluctuations of critical eigenstates are investigated for a disordered two dimensional model of non-interacting electrons subject to spin-orbit scattering (Ando model). For square samples, we verify numerically the relation $\sigma_c=1/[2\pi(2-D(1))] e^2/h$ between critical conductivity $\sigma_c=g_c=(1.42\pm 0.005) e^2/h$ and the fractal information dimension of the electron wave function, $D(1)=1.889\pm 0.001$. Through a detailed numerical scaling analysis of the two-terminal conductance we also estimate the critical exponent $\nu=2.80\pm 0.04$ that governs the quantum phase transition.Comment: IOP Latex, 7 figure

The two electron artificial molecule

Exact results for the classical and quantum system of two vertically coupled two-dimensional single electron quantum dots are obtained as a function of the interatomic distance (d) and with perpendicular magnetic field. The classical system exhibits a second order structural transition as a function of d which is smeared out and shifted to lower d values in the quantum case. The spin-singlet - spin-triplet oscillations are shifted to larger magnetic fields with increasing d and are quenched for a sufficiently large interatomic distance.Comment: 4 pages, 4 ps figure