A two band model for Superconductivity: Probing interband pair formation

We propose a two band model for superconductivity. It turns out that the simplest nontrivial case considers solely interband scattering, and both bands can be modeled as symmetric (around the Fermi level) and flat, thus each band is completely characterized by its half-band width $W_{n}$ (n=1,2). A useful dimensionless parameter is $\delta$, proportional to $W_{2}-W_{1}$. The case $\delta =0$ retrieves the conventional BCS model. We probe the specific heat, the ratio gap over critical temperature, the thermodynamic critical field and tunneling conductance as functions of $\delta$ and temperature (from zero to $T_{c}$). We compare our results with experimental results for $MgB_{2}$ and good quantitative agreement is obtained, indicating the relevance of interband coupling. Work in progress also considers the inclusion of band hybridization and general interband as well as intra-band scattering mechanisms.Comment: 7 pages, 5 figures (in postscript format). PACS numbers: 74.20.-z, 74.20.Fg, 74.70.A

Magnetoresistance and transistor-like behavior of double quantum dots connected to ferromagnetic and superconductor leads

The electric current and the magnetoresistance effect are studied in a double quantum-dot system, where one of the dots QDa is coupled to two ferromagnetic electrodes (F1,F2), while the second QDb is connected to a superconductor S. For energy scales within the superconductor gap, electric conduction is allowed by Andreev reflection processes. Due to the presence of two ferromagnetic leads, non-local crossed Andreev reflections are possible. We found that the magnetoresistance sign can be changed by tuning the external potential applied to the ferromagnets. In addition, it is possible to control the current of the first ferromagnet (F1) through the potential applied to the second one (F2). We have also included intradot interaction and gate voltages at each quantum dot and analyzed their influence through a mean field approximation. The interaction reduces the current amplitudes with respect to the non-interacting case, but the switching effect still remains as a manifestation of quantum coherence, in scales of the order of the superconductor coherence length.Comment: Revised versio

Peer Mentors and Writing Center Tutors: What our collaborations taught us about serving the SJSU Freshmen Students

The Library Outpost, a satellite office of the campus’s Dr. Martin Luther King Jr. Library, seeks ways to reach out to First Year students who are new to writing research papers. One of our goals is to meet the First Year students on their own turf. Since the Peer Mentors and Writing Center tutors have peer relationships with the First year students, we want to learn how we can collaborate with them to provide services to the First year students. We surveyed the Peer Mentors and Writing Center Tutors to assess their perceptions of their own research skills, and their students’ research needs to guide the services and workshops offered by the Library Outpost

USDA's Livestock Gross Margin Insurance for Dairy: What Is It and How Can It Be Used for Risk Management

Dairy farmers are faced with tremendous and increasing volatility, both in terms of milk prices, and the costs of purchased feed. There is a new weapon in the risk management arsenal of U.S. dairy producers: the Livestock Gross Margin for Dairy (LGM-Dairy) insurance program controls for lower gross revenue, defined as the value of milk produced minus feed costs. This program is administered by USDA's Risk Management Agency, and made available via authorized crop insurance agents to dairy farm operators in the lower 48 states.

Slow light in molecular aggregates nanofilms

We study slow light performance of molecular aggregates arranged in nanofilms by means of coherent population oscillations (CPO). The molecular cooperative behavior inside the aggregate enhances the delay of input signals in the GHz range in comparison with other CPO-based devices. Moreover, the problem of residual absorption present in CPO processes, is removed. We also propose an optical switch between different delays by exploiting the optical bistability of these aggregates.Comment: 4 pages, 4 figure