A comparative analysis of two educational reform movements in America : the Eight Year Study and a Nation at Risk

http://www.worldcat.org/oclc/2430799

Asymmetric superconductivity in metallic systems

Different types of superfluid ground states have been investigated in systems of two species of fermions with Fermi surfaces that do not match. This study is relevant for cold atomic systems, condensed matter physics and quark matter. In this paper we consider this problem in the case the fermionic quasi-particles can transmute into one another and only their total number is conserved. We use a BCS approximation to study superconductivity in two-band metallic systems with inter and intra-band interactions. Tuning the hybridization between the bands varies the mismatch of the Fermi surfaces and produces different instabilities. For inter-band attractive interactions we find a first order normal-superconductor and a homogeneous metastable phase with gapless excitations. In the case of intra-band interactions, the transition from the superconductor to the normal state as hybridization increases is continuous and associated with a quantum critical point. The case when both interactions are present is also considered.Comment: new enlarged version, new title, 7 pages, 7 figure

Sistemas de producción de patata y otras hortalizas: procesos de producción, organización y consumo de productos ecológicos en Andalucía/España.

bitstream/item/43963/1/documento-329.pd

A Surgery Table with a Mouth Prop for Rodents

Laboratory animal research represents a remarkable source of information. Rodents are often used as an  experimental model for studies in the medical field, showing several advantages. The access to the oral  cavity allows one to examine it and to perform surgical restorative procedures. The application of topical  substances on hard tissues and mucosa is also possible. Literature includes reports on mouth-opening systems  for animals, but they are not available on the market. Therefore, researchers must improvise methods  that allow access to the oral cavity, but which may compromise the experiment. The purpose of this technical  report is to introduce an inexpensive and easy-to-use surgery table containing a device for rodent  mouth opening, which facilitates access to the oral cavity, maintaining mouth-opening and spreading the  cheeks apart.

Warm and Dry Spells (WDS) in Austral Winter over Central South America

The horizontal and vertical structure of unusually warm and dry spells (WDS) over the central parts of South America during the winter and post-winter months (JJAS) are studied. During WDS the mean temperature and humidity anomalies over central Brazil are about +4.1°C and −13.2%, respectively. The mean duration of WDS is 11 days and their mean frequency is less than one per year during the months of JJAS. Apparently, WDS have no preference for the phase of ENSO. Widespread and persistent subsidence in the middle troposphere is observed in tropical Brazil during WDS, which renders the lower tropospheric air warm and dry. The negative anomalies of the specific humidity are observed to be associated with the subsidence regions. A strong, slow moving ridge in the eastern South Pacific and a low-pressure center in northern Argentina are important surface characteristics during the WDS. A more detailed investigation of two specific WDS events, a strong event (August–September 1999) and a moderate one (June 2002), shows a blocking-like situation in the 500-hPa geopotential and surface pressure fields in the Pacific. The South Atlantic subtropical high somewhat approaches the continent. Strong northerlies over the central and eastern parts of Brazil are also observed in the lower troposphere. During WDS the regional circulation acquires summertime characteristics, except for the absence of precipitation, and the circulation in the meridional plane is in the opposite sense from the Hadley circulation. A frontal system, supported by a 500-hPa trough, advances into central Brazil, causing the dissipation of the anomalous situation