Mottness at finite doping and charge-instabilities in cuprates.

The influence of the Mott physics on the doping-temperature phase diagram of copper oxides represents a major issue that is subject of intense theoretical and experimental effort. Here, we investigate the ultrafast electron dynamics in prototypical single-layer Bi-based cuprates at the energy scale of the O-2p→Cu-3d charge-transfer (CT) process. We demonstrate a clear evolution of the CT excitations from incoherent and localized, as in a Mott insulator, to coherent and delocalized, as in a conventional metal. This reorganization of the high-energy degrees of freedom occurs at the critical doping pcr ≈0.16 irrespective of the temperature, and it can be well described by dynamical mean field theory calculations. We argue that the onset of the low-temperature charge instabilities is the low-energy manifestation of the underlying Mottness that characterizes the p < pcr region of the phase diagram. This discovery sets a new framework for theories of charge order and low-temperature phases in underdoped copper oxides.

Positive social interdependence and classroom climate.

We explored the relationship between student perceptions of social interdependence and social support. Attitudinal responses to the Classroom Life Instrument (Johnson & Johnson, 1983; Johnson, Johnson, & Anderson, 1983; Johnson, Johnson, Buckman, & Richards, 1985) were gathered in Canada from four classes totaling 123 eighth-grade students learning geometry in cooperative groups. We extended previous findings by examining the relationships among the classroom climate variables, causal attributions, and achievement, and explored the consistency among the four classroom climate studies using statistical methods for meta-analysis to determine overall effect magnitudes and the degree of study-to-study variability. Social support from the teacher and fellow students was moderately related to perceptions of positive interdependence, but social interdependence factors were less important predictors of student learning than was student self-esteem.

Choosing the right information system for your hospital.

Thousands of information system products are available to the hospital manager. Therefore, it can be useful to have an overview of the major HIS vendors. In this discussion, the vendors' products are grouped by hospital size--large, medium, and small. With such a list, those interested in acquiring or upgrading a system will have the information necessary to begin the process.

Recruitment of college volunteers for community service organizations using the lecture method.

The present study was undertaken to determine those variables which best predict college students' reactions to lectures designed to solicit volunteers for a juvenile corrections program. One hundred and thirty-four students returned mailed questionnaires which assessed multiple variables related to: (1) audience characteristics, (2) recruiter (lecturer) characteristics, and (3) volunteer program (lecture content) characteristics. Results of canonical correlation analysis indicated that 8 of 17 predictor variables accounted for the majority of the variance in the volunteering behavior variate. Age of respondent, previous volunteer experience, overall lecture quality, understanding need for volunteer services, clarity and comprehension of volunteer roles, the value of the lecture as a significant learning experience, the opportunity for personal growth within the program, and the ability to influence existing structures were seen as important variables in predicting three volunteering behaviors. In particular, the data suggest that for recruitment programs using the lecture method recruiter characteristics have the greatest impact on soliciting volunteer personnel.