Method for establishing and measuring in vivo forces in an anterior cruciate ligament composite graft: response to differing levels of load sharing in a goat model

In order to determine the appropriate load history for optimal remodeling of an anterior cruciate ligament graft, methods for establishing and measuring the graft force due to an external load could be set to a preselected value in in vivo are required. Our objectives with this study were to (a) develop a method in which the graft force due to an external load could be set to a preselected value in a living animal, (b) show that this force could be maintained after fixation, and (c) determine what happens to the forces after the animal has functioned for as long as 2 weeks postoperatively, when differing levels of load sharing between the segments had been set at surgery. The anterior cruciate ligament was reconstructed in 12 goats with use of a bone-patellar tendon-bone graft and a synthetic augmentation device. The forces in the graft segments were established, at the time of surgical fixation, with use of a force-setting technique. In five animals, the tendon segment was set to carry 90% of the total graft force; in the remaining seven animals, the augmentation segment was set to share 90% of the total graft force. Graft forces were measured, with the use of buckle transducers mounted extra-articularly over the anterior tibia, under a 67 N anterior tibial load at 60 degrees of knee flexion before and after fixation and at 2 weeks postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Diethylpropion pharmacotherapeutic adjuvant therapy for inpatient treatment of cocaine dependence: a test of the cocaine-agonist hypothesis

Fifty cocaine-dependent patients completed a 2-week double-blind, double-dummy, parallel-group comparison of four dosage levels of diethylpropion and placebo. This clinical trial was designed to evaluate both diethylpropion's ability to attenuate cocaine cue-induced craving and its potential for development as a medication with cocaine-agonist properties. The results indicated that diethylpropion was not superior to placebo and confirmed earlier reports that craving for cocaine diminishes over the course of an inpatient hospitalization. Moreover, the results showed that the cocaine cue-induced craving paradigm employed is effective in stimulating craving for cocaine. Medications that are effective in attenuating this type of "conditioned" craving may have relevance to the breaking of the cycle of relapse and long-term treatment of cocaine dependence. Diethylpropion may not be an appropriate candidate for future medication development because of its lack of obvious therapeutic efficacy and the emergence of a significant number of side effects. However, a cocaine-agonist medication strategy may be appropriate for a subgroup of cocaine-dependent patients with coexisting attention deficit-hyperactivity disorder.     

PISA 2003—Mathematical Literacy and Learning in the Americas

Abstract

The article provides an overview of the mathematics assessment program of the Organization for Economic Cooperation and Developments’ (OECD) Program for Student Assessment (PISA). As such, it provides a comparative view of the PISA results for Canada, Mexico, and the United States. It outlines the program, its frameworks, and competencies PISA uses to describe the achievement of 15-year-olds in over 40 countries participating in the PISA assessments. Particular attention is given to the PISA conception of mathematical literacy and cross-disciplinary problem-solving. These two areas were a focus of the 2003 assessment. In addition to a discussion of general results, two sample problems are presented, one from the mathematical literacy and one from cross-disciplinary problem-solving, along with detailed information about student performances in the items. The article concludes with a consideration of the lessons to be learned from the PISA study relative to the teaching and learning of mathematics.     

Amygdala lesions block conditioned enhancement of the early component of the rat eyeblink reflex.

A tone-conditioned stimulus (CS) previously paired with a grid shock unconditioned stimulus (US) can greatly enhance the early electromyographic (EMG) component (RI) of the rat eyeblink reflex. The hypothesis that the central nucleus of the amygdala (ACe) is an essential part of the circuitry mediating conditioned RI enhancement was tested. After bilateral ACe lesions (L) or a sham operation (S), rats received paired presentations of the CS and US (P) or explicitly unpaired CS and US presentations (U), resulting in 4 groups: P/S, P/L, U/S, and U/L. ACe lesions completely prevented conditioned RI enhancement, which was only exhibited in Group P/S. In the latter group, the "preextinction" conditioned enhancement effect was roughly a 2-fold increase in the RI magnitude. Circuit-level mechanisms are discussed, and some advantages of the eyeblink EMG response in this general conditioning paradigm are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An image analysis algorithm for dendritic spines

The structure of neuronal dendrites and their spines underlie the connectivity of neural networks. Dendrites, spines, and their dynamics are shaped by genetic programs as well as sensory experience. Dendritic structures and dynamics may therefore be important predictors of the function of neural networks. Based on new imaging approaches and increases in the speed of computation, it has become possible to acquire large sets of high-resolution optical micrographs of neuron structure at length scales small enough to resolve spines. This advance in data acquisition has not been accompanied by comparable advances in data analysis techniques; the analysis of dendritic and spine morphology is still accomplished largely manually. In addition to being extremely time intensive, manual analysis also introduces systematic and hard-to-characterize biases. We present a geometric approach for automatically detecting and quantifying the three-dimensional structure of dendritic spines from stacks of image data acquired using laser scanning microscopy. We present results on the measurement of dendritic spine length, volume, density, and shape classification for both static and time-lapse images of dendrites of hippocampal pyramidal neurons. For spine length and density, the automated measurements in static images are compared with manual measurements. Comparisons are also made between automated and manual spine length measurements for a time-series data set. The algorithm performs well compared to a human analyzer, especially on time-series data. Automated analysis of dendritic spine morphology will enable objective analysis of large morphological data sets. The approaches presented here are generalizable to other aspects of neuronal morphology.     

Experimental evidence showing that stochastic subspace identification methods may fail

It is known that certain popular stochastic subspace identification methods may fail for theoretical reasons related to positive realness. In fact, these algorithms are implicitly based on the assumption that the positive and algebraic degrees of a certain estimated covariance sequence coincide. In this paper, we describe how to generate data with the property that this condition is not satisfied. Using these data we show through simulations that several subspace identification algorithms exhibit massive failure.     

The Inverse Problem of Analytic Interpolation With Degree Constraint and Weight Selection for Control Synthesis

The minimizers of certain weighted entropy functionals are the solutions to an analytic interpolation problem with a degree constraint, and all solutions to this interpolation problem arise in this way by a suitable choice of weights. Selecting appropriate weights is pertinent to feedback control synthesis, where interpolants represent closed-loop transfer functions. In this paper we consider the correspondence between weights and interpolants in order to systematize feedback control synthesis with a constraint on the degree. There are two basic issues that we address: we first characterize admissible shapes of minimizers by studying the corresponding inverse problem, and then we develop effective ways of shaping minimizers via suitable choices of weights. This leads to a new procedure for feedback control synthesis.      

A method for integrating MODIS and Landsat data for systematic monitoring of forest cover and change in the Congo Basin

In this paper we demonstrate a new approach that uses regional/continental MODIS (MODerate Resolution Imaging Spectroradiometer) derived forest cover products to calibrate Landsat data for exhaustive high spatial resolution mapping of forest cover and clearing in the Congo River Basin. The approach employs multi-temporal Landsat acquisitions to account for cloud cover, a primary limiting factor in humid tropical forest mapping. A Basin-wide MODIS 250 m Vegetation Continuous Field (VCF) percent tree cover product is used as a regionally consistent reference data set to train Landsat imagery. The approach is automated and greatly shortens mapping time. Results for approximately one third of the Congo Basin are shown. Derived high spatial resolution forest change estimates indicate that less than 1% of the forests were cleared from 1990 to 2000. However, forest clearing is spatially pervasive and fragmented in the landscapes studied to date, with implications for sustaining the region's biodiversity. The forest cover and change data are being used by the Central African Regional Program for the Environment (CARPE) program to study deforestation and biodiversity loss in the Congo Basin forest zone. Data from this study are available at http://carpe.umd.edu.     

Capacitive Transduction for Liquid Crystal-Based Sensors, Part I: Ordered System

In this paper, the theory for tracking the average molecular orientation of a liquid crystal (LC) material via capacitive sensing of anisotropic media is presented. The candidate LC sensor structure utilizes interdigital electrodes. Two capacitive measurements in orthogonal direction can track the director axis of nematic LC material in a homogenous ordered LC film. The sensitivity for the sensor at different alignments is studied. The candidate sensors have been fabricated and experimentally verified. Both experimental and calculated values for capacitances of selected interdigital fingers sensor structures are presented.     

Selection of college student therapeutic agents: Further analysis of the "group assessment of interpersonal traits" technique.

Assigned each of 84 male undergraduates to a 4-person assessment of interpersonal traits session to evaluate the technique and to determine the extent to which group members who model either positive or negative attributes affect and/or distort others' individual performances. Results suggest that the technique is a conservative selection device and can be recommended for its efficiency over individual interviews. (PsycINFO Database Record (c) 2010 APA, all rights reserved)