Enhanced quantum tunnelling induced by disorder

We reconsider the problem of the enhancement of tunnelling of a quantum particle induced by disorder of a one-dimensional tunnel barrier of length $L$, using two different approximate analytic solutions of the invariant imbedding equations of wave propagation for weak disorder. The two solutions are complementary for the detailed understanding of important aspects of numerical results on disorder-enhanced tunnelling obtained recently by Kim et al. (Phys. rev. B{\bf 77}, 024203 (2008)). In particular, we derive analytically the scaled wavenumber $(kL)$-threshold where disorder-enhanced tunnelling of an incident electron first occurs, as well as the rate of variation of the transmittance in the limit of vanishing disorder. Both quantities are in good agreement with the numerical results of Kim et al. Our non-perturbative solution of the invariant imbedding equations allows us to show that the disorder enhances both the mean conductance and the mean resistance of the barrier.Comment: 10 page

Transmission, reflection and localization in a random medium with absorption or gain

We study reflection and transmission of waves in a random tight-binding system with absorption or gain for weak disorder, using a scattering matrix formalism. Our aim is to discuss analytically the effects of absorption or gain on the statistics of wave transport. Treating the effects of absorption or gain exactly in the limit of no disorder, allows us to identify short- and long lengths regimes relative to absorption- or gain lengths, where the effects of absorption/gain on statistical properties are essentially different. In the long-lengths regime we find that a weak absorption or a weak gain induce identical statistical corrections in the inverse localization length, but lead to different corrections in the mean reflection coefficient. In contrast, a strong absorption or a strong gain strongly suppress the effect of disorder in identical ways (to leading order), both in the localization length and in the mean reflection coefficient.Comment: Important revisions and expansion caused by a crucial property of $\hat Q

Client-Server Computing: Getting your Feet Wet

Tremendous growth of client-server (C-S) computing is expected throughout the 1990s. Computer information systems (CIS) curricula are faced with the ongoing challenge of providing client-server instruction while technologies and methodologies are still evolving. To keep pace with this dynamic environment, faculty must begin building initial client-server experiences into the CIS curriculum. The purpose of this paper is to describe one institution\u27s experiences getting its client-server feet wet. First, fundamental concepts of client-server are considered. Second, basic questions about introducing C-S to the CIS curriculum are addressed. Next, the introduction of client-server computing at Western Carolina University is described. Finally, future client-server changes are considered

Workshop: Exploring Microsoft’s Sharepoint Server

SharePoint Server provides functions and features for enterprise portal development, workgroup collaboration, and knowledge sharing. Its functionality can stand alone or be extended through Microsoft’s Office products. The purpose of the workshop will be to explore the SharePoint environment and consider its role as a development tool in a CIS program. The workshop will provide an overview of the SharePoint product, present ideas for implementing SharePoint development in a CIS program, and discuss implications for faculty interested in taking the SharePoint plunge

Integration of Host Plant Resistance and Insecticides in the Control of \u3ci\u3eNephotettix virescens\u3c/i\u3e (Homoptera: Cicadelli-dae), a Vector of Rice Tungro Virus

Combined effects of levels of vector resistance and insecticide application in control of rice tungro virus (RTV) were determined in three field tests. Cultivar “IR28,” with high levels of resistance to the vector, Nephotettix virescens (Distant), had low RTV infection in all treatments including the untreated check. In moderately resistant “IR36,” RTV decreased with an increase in level of insecticide but did not decrease to a level equaling the untreated “IR28.” The N. virescens-susceptible cultivar “IR22” had extremely high levels of RTV infection at all insecticide levels. Economic analysis indicated that gross profit and net gain were highest in the N. virescens-resistant “IR28,” intermediate in moderately resistant “IR36,” and lowest in susceptible “IR22.

Oxytocin and intergroup relations: Goodwill is not a fixed pie

peer reviewe

Management of the Rice Tungro Virus Vector \u3ci\u3eNephotettix virescens\u3c/i\u3e (Homoptera: Cicadellidae) with Controlled-Release Formulations of Carbofuran

Field trials were conducted in lowland flooded rice in the Philippines to evaluate a number of carbofuran controlled-release formulations in comparison with commercial formulations. The test formulations were based on a biodegradable matrix of pine kraft lignin and were used as granules of different sizes and also in the form of small strips. The release rates were assessed under field conditions by bioassaying rice plants in the field, using adult rice green leafhopper, Nephotettix virescens Distant. The lignin formulations with a high level of active ingredient (15–45% by weight) gave as good or better control than the commercial 3% granules in tests based on three application techniques: broadcast into the floodwater, soil incorporation, and root zone injection. The improvements in control levels of green leafhoppers were most marked with soil incorporation and root zone application. The best lignin-based formulation reduced levels of tungro virus infection from 23% for a conventional flowable carbofuran formulation to 1.0% at an application rate of 0.5 kg (AI)/ha. At the same rate, the grain yield was increased from 3.56 t/ha to 5.5 t/ha, using the controlled-released formulation

Feed the Future IPM Innovation Lab: A Critical Role in Global Food Security

The World Food Summit of 1966 defined ”food security” as existing “when all people at all times have access to sufficient, safe, and nutritious food to maintain a healthy and active life.” Food insecurity is part of a continuum that includes hunger (food deprivation), malnutrition (deficiencies, imbalances, or excess of nutrients), and famine. The world faces three major challenges: (1) to match the rapidly changing demand for food, (2) to do so in ways that are environmentally and socially acceptable, and (3) to ensure that the world’s poorest people are no longer hungry. World population is expected to reach 9 billion in 2050. To feed this population, there must be a 60–70% increase in food production. The effects of climate change must also be dealt with. The area under cultivation is not expected to expand to meet the gap, and we have yet to meet it by increasing yield per unit area and reducing losses in field and post-harvest handling. A concerted effort to reduce losses without jeopardizing environmental and public health concerns by adopting Integrated Pest Management (IPM) could reduce the loss by 50%, leading to a needed increase in food production of only 30%. Over several decades, the IPM Collaborative Research Program (CRSP) consortium developed IPM packages for tomatoes, other tropical vegetables, fruit, and grain crops and disseminated in host countries through research and extension arms. In addition, several national, regional, and international workshops have been conducted. The IPM Innovation Lab (new name for CRSP in 2013) is playing a vital role in the struggle for global food security. This will continue through the new Feed the Future IPM Innovation Lab which has expanded beyond a limited number of vegetables to include more vegetables, rice, fruit, maize, chickpea, climate change, and invasive species

Exact transmission moments in one-dimensional weak localization and single-parameter scaling

We obtain for the first time the expressions for the mean and the variance of the transmission coefficient for an Anderson chain in the weak localization regime, using exact expansions of the complex transmission- and reflection coefficients to fourth order in the weakly disordered site energies. These results confirm the validity of single-parameter scaling theory in a domain where the higher transmission cumulants may be neglected. We compare our results with earlier results for transmission cumulants in the weak localization domain based on the phase randomization hypothesis

Relação fósforo e magnésio na fertilidade do solo, no estado nutricional e na produção da alfafa.

Com o objetivo de avaliar a influência da relação P:Mg na fertilidade do solo, no estado nutricional e na produção de matéria seca da alfafa, foi realizado um experimento em vasos com Latossolo Vermelho Amarelo distrófico, segundo delineamento inteiramente casualizado, em esquema de parcelas subdivididas, com três repetições. Os tratamentos foram constituídos de combinações de P (doses: 0, 100, 200 e 400 mg kg-1, fonte: superfosfato triplo) e Mg (doses: 0, 100 e 200 mg kg-1, fonte: cloreto de magnésio), nas proporções de 0, 0,5, 1, 2 e 4. No período experimental, foram realizados três cortes, com intervalo de 30 dias (subparcelas). Os resultados demonstraram que o incremento da relação P:Mg e das doses de P e de Mg aumenta a produção de matéria seca. O teor de P e as combinações de P:Mg no tecido vegetal apresentaram estreita relação com a proporção desses nutrientes no solo. A relação 2:1 acarretou maior teor de clorofila e N na matéria seca, enquanto altas quantidades de P no solo diminuíram a absorção de K