Predicting Acute Renal Failure after Cardiac Surgery: Validation and Re‐definition of a Risk‐Stratification Algorithm

Background:  Acute renal failure (ARF) after cardiac surgery is associated with significant morbidity and mortality, irrespective of the need for dialysis. Previous studies have attempted to identify predictors of ARF and develop risk stratification algorithms. This study aims to validate the algorithm in an independent cohort of patients that includes a significant proportion of female and black patients and compares two different definitions of renal outcome.
Methods:  A large single center cardiac surgery database was examined (n, 24,660; 1993–2000) which included 29.9% females and 3.7% black patients. Post‐operative ARF was defined as: a) ARF requiring dialysis, b) > 50% reduction in creatinine clearance relative to baseline or requiring dialysis. Clinical variables related to baseline renal function and cardiovascular disease were used in recursive partitioning analysis for both outcome definitions. Chi‐square goodness of fit analysis was performed to validate the algorithm.
Results:  The frequency of post‐operative ARF requiring dialysis ranged between 0.5 and 15.5% based on the risk categories with the area under the receiver operating characteristic (ROC) curve of 0.78. Using the more inclusive definition of ARF, the frequency was significantly higher ranging from 2.6 to 25%(P < 0.001) with an area under ROC curve of 0.65.
Conclusions:  The renal risk stratification algorithm is valid in predicting post‐operative ARF in an independent cohort of patients, well represented by differences in gender and race. Since the need for dialysis remains subjective, a more objective and inclusive definition of ARF may help in identifying a larger number of patients 'at‐risk'.     

High performance air pollution modeling for a power plant environment

The aim of this work is to provide a high performance air quality simulation using the STEM-II (Sulphur Transport Eulerian Model 2) program, a large-scale pollution modeling application. First, we optimize the sequential program with the aim of increasing data locality. Then, we parallelized the program using OpenMP directives for shared memory systems, and the MPI library for distributed memory machines. Performance results are presented for a SGI O2000 multiprocessor, a Fujitsu AP3000 multicomputer and a Cluster of PCs. Experimental results show that the parallel versions of the code achieve important reductions in the CPU time needed by each simulation. This will allow us to obtain results with adequate speed and reliability for the industrial environment where it is intended to be applied.     

How social comparison mediates the relation between ability-grouping practices and students' achievement expectancies in mathematics.

This investigation tested the hypothesis that social comparison processes mediate the relation between ability-grouping practices in mathematics and students' achievement expectancies in a district-wide sample of 6th graders (N?=?452). Compared with between-classroom ability grouping, within-classroom grouping raises high achievers' achievement expectancies, math grades, and tendency to make downward comparisons (i.e., with a classmate who is worse at math). Within-classroom grouping lowers low achievers' expectancies and math grades and increases their tendency to make upward comparisons. When controls for the direction of students' social comparison choices and for their mathematics grades are introduced, the independent effect of ability grouping on achievement expectancies is consistently and substantially reduced. It is argued that ability-grouping practices constrain the choices available to students and teachers for social comparison of abilities and thereby influence the frame of reference students use for self-assessment and teachers use for assigning grades. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

British female academics and comparative psychology: Attempts to establish a research niche in the early 20th century.

Why was there a preponderance of women engaged in laboratory-based studies of animal behavior in Britain in the early years of the 20th century? As a new experimental subject with recently neglected potential, animal psychology then represented an opportunity for women to make further inroads into academic science. Because the study of psychology before World War I offered negligible professional opportunities for the application of the subject, the intake of students was restricted. Perhaps this encouraged academic access to it by aspiring female scientists who felt that career prospects, uncertain and socially unexpected of them in any case, were worth chancing for greater long-term rewards. The academic circumstances and contributions of 3 British female pioneers in experimental comparative psychology are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Toward bridging the science and practice of depression prevention: What can we learn from cognitive vulnerability?

Depression is a widespread disorder with devastating individual and societal consequences. Although a great deal of research and theory has focused on treatment of acute episodes, progress needs to be made in preventing the emergence of first episodes of the disorder. There has been considerable advancement in understanding psychological vulnerability factors associated with this mood disorder, especially on the basis of cognitive behavioural models and research findings based on this theoretical model. In this paper we review the concept of cognitive vulnerability, with a particular focus on what this body of research work suggests clinically for the prevention of depression. We outline, based on this science, what the effective ingredients of a prevention program could be. We also discuss some of the pragmatic aspects of developing an effective prevention program for depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Copper-zirconium tungstate composites exhibiting low and negative thermal expansion influenced by reinforcement phase transformations

A fully-dense Cu-75 vol pct ZrW₂O₈ metal matrix composite was fabricated by hot isostatic pressing of Cu-coated ZrW₂O₈ particles. A small amount of the high-pressure γ-ZrW₂O₈ phase was created during the cooldown and depressurization following densification; near complete transformation to γ-ZrW₂O₈ was achieved by subsequent cold isostatic pressing. The thermal expansion behavior of the composite between 25°C and 325°C was altered by the cold isostatic pressing treatment, and also depended on the length of time that had passed between thermal cycles. The measured thermal expansion coefficients within specific temperature ranges varied from −6·10⁻⁶ K⁻¹ to far above the thermal expansion coefficient of the copper matrix. The complex temperature-dependent expansion/contraction behavior could be justified by considering the evolution of phase transformations taking place in the ZrW₂O₈ phase, which were observed by in-situ synchrotron X-ray diffraction measurements.     

An experiment for showing some kind of artificial understanding

In this paper we design an experiment which can be depicted as a simple scenario, a very limited 'world'. In this world, there are an actor that can pursue a project and an observer that is keeping its eyes on the actor. We try to show in the experiment that the observer can to some degree understand the actor based on its knowledge and some metaphors, i.e. understand what the actor is doing and why. As the conclusion of this experiment, we try to show some features of 'understanding'. These are (1) that 'understanding' has to be based on some preliminary knowledge; (2) that 'understanding' is a process of incremental learning; (3) that, as for symbolic systems, some metaphors are necessary for mapping real entities into concepts in mind.     

Another Perspective on Vocabulary Richness

This article examines the usefulness ofvocabulary richness for authorship attributionand tests the assumption that appropriatemeasures of vocabulary richness can capture anauthor's distinctive style or identity. Afterbriefly discussing perceived and actualvocabulary richness, I show that doubling andcombining texts affects some measures incomputationally predictable but conceptuallysurprising ways. I discuss some theoretical andempirical problems with some measures anddevelop simple methods to test how wellvocabulary richness distinguishes texts bydifferent authors. These methods show thatvocabulary richness is ineffective for largegroups of texts because of the extremevariability within and among them. I concludethat vocabulary richness is of marginal valuein stylistic and authorship studies because thebasic assumption that it constitutes awordprint for authors is false.     

Standing on Solid Ground

The new Editor in Chief of IEEE Micro introduces himself and the first issue of 2007. He thanks outgoing Editor in Chief Pradip Bose for his outstanding work on Micro during his tenure. He assesses the current state of the microarchitecture field, speculates on the future, and asks readers for their suggestions on topics the magazine should cover in coming issues.     

Lateral Walking-Induced Forces on Footbridges

In the last several years many cases of large amplitude horizontal vibrations of footbridges have been observed, due to dynamic interaction between the walkers and the footbridge, which may occur when some conditions on the bridge mass, frequency and damping, as well as on the crowd density are met. Such interaction is an intriguing phenomenon, as it is associated with the dynamics of a complex system made of a structure and a number of walkers, the dynamics of the latter being governed by physiology and psychology. Provided this complexity, in this paper a preliminary step is made toward the modeling of the interaction forces exerted by a crowd to a footbridge. The results of an experimental investigation of the lateral forces exerted by one walker to a fixed floor are presented, and used to calibrate a deterministic and stochastic lateral loading models of footbridges, to be used in the case in which no interaction takes place. The results presented are also the background data for more sophisticated dynamic models allowing for bridge-crowd interaction.