bluuebunny/crossref_metadata_2025 huggingface dataset:
Does the International Classification of Disease (ICD-9) Code Accurately Identify Neonates Who Clinically Have Hypoxic-Ischemic Encephalopathy?
Authors: Vance Gregory A. , Niederhauser Amy , Chauhan Suneet P. , Magann Everett F. , Dahlke Joshua D. , Muraskas Jonathan K. , Morrison John C.
Published: April 2011

Background/Aims: Hypoxic-ischemic encephalopathy (HIE) refers to neonatal neurological signs and symptoms of hypoxia and/or ischemia. Our aim was to determine the accuracy of ICD-9 codes to identify newborns with HIE confirmed by umbilical cord blood analysis. Methods: ICD-9 codes in the newborn chart for birth trauma, birth asphyxia, intrauterine hypoxia, and fetal distress were used to identify newborns with suspected HIE by neonatal personnel. Maternal charts were reviewed for umbilical cord gases meeting the HIE clinical criteria. Results: There were 21,008 deliveries at center I and 17,540 at center II. ICD-9 codes identified 172 neonates, 49 infants (2.3‰ births) at center I and 123 neonates (7‰) at center II. Only 3 neonates (6%) were ≧34 weeks and none met ACOG criteria [umbilical artery pH <7.00 or base excess (BE) ≧12 mmol/l at center I]. At center II, 80 infants were ≧34 weeks but only 5/123 (4%) met the ACOG clinical criteria for HIE (pH <7.00, BE ≧12 mmol/l, and Apgar ≤3 at 5 min). Conclusions: ICD-9 codes are unreliable in identifying birth asphyxia and cannot identify newborns meeting the clinical criteria for intrapartum HIE.
A Noradrenergic Sensitive Endogenous Clock Is Present in the Rat Pineal Gland
Authors: Wongchitrat Prapimpun , Felder-Schmittbuhl Marie-Paule , Govitrapong Piyarat , Phansuwan-Pujito Pansiri , Simonneaux Valérie
Published: April 2011

The aim of this study was to examine the occurrence of endogenous oscillations of Per1, Per2, Bmal1 and Rev-erbα genes in rat pineal explants and to investigate their regulation by adrenergic ligands. Our results show a significant and sustained rhythm of Per2,Bmal1 and Rev-erbα gene expression for up to 48 h in cultured pineal gland with a pattern similar to that observed in vivo. By contrast, the rhythms of Per1 and Aa-nat, the rate-limiting enzyme for melatonin synthesis, were strongly attenuated after 24 h in culture. Addition of the exogenous adrenergic agonist isoproterenol on cultured pineal glands induced a short-term increase in mRNA levels of Per1 and Aa-nat, but not those of Per2,Bmal1 and Rev-erbα. This study demonstrates that the rat pineal gland hosts a circadian oscillator as evidenced by the sustained, noradrenergic-independent, endogenous oscillations of Per2, Bmal1 and Rev-erbα mRNA levels in cultured tissues. Only expression of Per1 was stimulated by adrenergic ligands suggesting that, in vivo, the adrenergic input could synchronize the pineal clock by acting selectively on Per1.
Glutathione Peroxidase-3 Deficiency Promotes Platelet-Dependent Thrombosis In Vivo
Authors: Jin Richard C. , Mahoney Christopher E. , (Coleman) Anderson Laura , Ottaviano Filomena , Croce Kevin , Leopold Jane A. , Zhang Ying-Yi , Tang Shiow-Shih , Handy Diane E. , Loscalzo Joseph
Published: April 2011

Background—

Glutathione peroxidase-3 (GPx-3) is a selenocysteine-containing plasma protein that scavenges reactive oxygen species in the extracellular compartment. A deficiency of this enzyme has been associated with platelet-dependent thrombosis, and a promoter haplotype with reduced function has been associated with stroke risk.

Methods and Results—

We recently developed a genetic mouse model to assess platelet function and thrombosis in the setting of GPx-3 deficiency. The GPx-3
(−/−)
mice showed an attenuated bleeding time and an enhanced aggregation response to the agonist ADP compared with wild-type mice. GPx-3
(−/−)
mice displayed increased plasma levels of soluble P-selectin and decreased plasma cyclic cGMP compared with wild-type mice. ADP infusion-induced platelet aggregation in the pulmonary vasculature produced a more robust platelet activation response in the GPx-3
(−/−)
than wild-type mice; histological sections from the pulmonary vasculature of GPx-3
(−/−)
compared with wild-type mice showed increased platelet-rich thrombi and a higher percentage of occluded vessels. Cremaster muscle preparations revealed endothelial dysfunction in the GPx-3
(−/−)
compared with wild-type mice. With a no-flow ischemia-reperfusion stroke model, GPx-3
(−/−)
mice had significantly larger cerebral infarctions compared with wild-type mice and platelet-dependent strokes. To assess the neuroprotective role of antioxidants in this model, we found that manganese(III) meso-tetrakis(4-benzoic acid)porphyrin treatment reduced stroke size in GPx-3
(−/−)
mice compared with vehicle-treated controls.

Conclusions—

These findings demonstrate that GPx-3 deficiency results in a prothrombotic state and vascular dysfunction that promotes platelet-dependent arterial thrombosis. These data illustrate the importance of this plasma antioxidant enzyme in regulating platelet activity, endothelial function, platelet-dependent thrombosis, and vascular thrombotic propensity.
Lapaquistat Acetate
Authors: Stein Evan A. , Bays Harold , O'Brien Dennis , Pedicano Jim , Piper Edward , Spezzi Andrea
Published: April 2011

Background—

Lapaquistat acetate is a squalene synthase inhibitor investigated for the treatment of hypercholesterolemia.

Methods and Results—

This report summarizes the phase 2 and 3 results from the lapaquistat clinical program, which was halted at an advanced stage as a result of potential hepatic safety issues. Efficacy and safety data were pooled from 12 studies (n=6151). These were 6- to 96-week randomized, double-blind, parallel, placebo- or active-controlled trials with lapaquistat monotherapy or coadministration with other lipid-altering drugs in dyslipidemic patients, including a large (n=2121) 96-week safety study. All studies included lapaquistat 100 mg daily; 5 included 50 mg; and 1 included 25 mg. The main outcome measures were the percent change in low-density lipoprotein cholesterol, secondary lipid/metabolic parameters, and overall safety. Lapaquistat 100 mg significantly decreased low-density lipoprotein cholesterol by 21.6% in monotherapy and by 18.0% in combination with a statin. It also reduced other cardiovascular risk markers, such as C-reactive protein. Total adverse events were higher for lapaquistat than placebo, although individual events were generally similar. At 100 mg, there was an increase in alanine aminotransferase value ≥3 times the upper limit of normal on ≥2 consecutive visits (2.0% versus 0.3% for placebo in the pooled efficacy studies; 2.7% versus 0.7% for low-dose atorvastatin in the long-term study). Two patients receiving lapaquistat 100 mg met the Hy Law criteria of alanine aminotransferase elevation plus increased total bilirubin.

Conclusions—

Squalene synthase inhibition with lapaquistat acetate, alone or in combination with statins, effectively lowered low-density lipoprotein cholesterol in a dose-dependent manner. Elevations in alanine aminotransferase, combined with a rare increase in bilirubin, presented potential hepatic safety issues, resulting in termination of development. The lapaquistat experience illustrates the current challenges in lipid-altering drug development.

Clinical Trial Registration—

URL:
http://www.clinicaltrials.gov
. Unique identifiers: NCT00487994, NCT00143663, NCT00143676, NCT00864643, NCT00263081, NCT00286481, NCT00249899, NCT00249912, NCT00813527, NCT00256178, NCT00268697, and NCT00251680.
G Protein–Coupled Receptor Kinase 2 Activity Impairs Cardiac Glucose Uptake and Promotes Insulin Resistance After Myocardial Ischemia
Authors: Ciccarelli Michele , Chuprun J. Kurt , Rengo Giuseppe , Gao Erhe , Wei Zhengyu , Peroutka Raymond J. , Gold Jessica I. , Gumpert Anna , Chen Mai , Otis Nicholas J. , Dorn Gerald W. , Trimarco Bruno , Iaccarino Guido , Koch Walter J.
Published: April 2011

Background—

Alterations in cardiac energy metabolism downstream of neurohormonal stimulation play a crucial role in the pathogenesis of heart failure. The chronic adrenergic stimulation that accompanies heart failure is a signaling abnormality that leads to the upregulation of G protein–coupled receptor kinase 2 (GRK2), which is pathological in the myocyte during disease progression in part owing to uncoupling of the β-adrenergic receptor system. In this study, we explored the possibility that enhanced GRK2 expression and activity, as seen during heart failure, can negatively affect cardiac metabolism as part of its pathogenic profile.

Methods and Results—

Positron emission tomography studies revealed in transgenic mice that cardiac-specific overexpression of GRK2 negatively affected cardiac metabolism by inhibiting glucose uptake and desensitization of insulin signaling, which increases after ischemic injury and precedes heart failure development. Mechanistically, GRK2 interacts with and directly phosphorylates insulin receptor substrate-1 in cardiomyocytes, causing insulin-dependent negative signaling feedback, including inhibition of membrane translocation of the glucose transporter GLUT4. This identifies insulin receptor substrate-1 as a novel nonreceptor target for GRK2 and represents a new pathological mechanism for this kinase in the failing heart. Importantly, inhibition of GRK2 activity prevents postischemic defects in myocardial insulin signaling and improves cardiac metabolism via normalized glucose uptake, which appears to participate in GRK2-targeted prevention of heart failure.

Conclusions—

Our data provide novel insights into how GRK2 is pathological in the injured heart. Moreover, it appears to be a critical mechanistic link within neurohormonal crosstalk governing cardiac contractile signaling/function through β-adrenergic receptors and metabolism through the insulin receptor.
Preoperative Factors Associated With Adverse Outcome After Tricuspid Valve Replacement
Authors: Topilsky Yan , Khanna Amber D. , Oh Jae K. , Nishimura Rick A. , Enriquez-Sarano Maurice , Jeon Yang B. , Sundt Thoralf M. , Schaff Hartzell V. , Park Soon J.
Published: April 2011

Background—

Preoperative factors associated with increased mortality and worse outcome after tricuspid valve replacement in patients with severe tricuspid regurgitation are poorly understood.

Methods and Results—

We retrospectively analyzed 189 patients (37% men; age, 67.5±11.3 years) who underwent tricuspid valve replacement for severe tricuspid regurgitation. Operative mortality rate was 10%, and was associated with intra-aortic balloon pump (odds ratio, 3.2; 95% confidence interval, 1.9 to 5.6;
P
<0.0001) or the presence of severe symptoms (New York Heart Association class IV relative to classes II and/or III) at the time of surgery (1.7; 95% confidence interval, 1.05 to 2.8;
P
=0.02). At the end of follow-up (29.3±27.1 months), 70 patients (37%) died, 6 (3%) needed tricuspid reoperation, and 41 (21.7%) were readmitted for heart failure. Seventy-eight patients (41.3%) were free from cardiovascular events (death, tricuspid reoperation, or heart failure admissions). The only echocardiographic parameter independently associated with adverse outcomes was a decrease in the right index of myocardial performance ratio. All-cause mortality was independently associated with a higher Charlson index (hazard ratio, 1.18; 95% confidence interval, 1.01 to 1.36;
P
=0.03), shorter right index of myocardial performance ratio (0.91; 95% confidence interval, 0.87 to 0.96;
P
=0.005), and preoperative New York Heart Association IV class (1.71; 95% confidence interval, 1.3 to 2.2;
P
<0.0001). In 68 patients with isolated tricuspid valve replacement, the associations between short right index of myocardial performance ratio, high Charlson index, New York Heart Association class IV, and increased mortality remained significant.

Conclusions—

Tricuspid valve replacement for severe tricuspid regurgitation can be performed with an acceptable operative mortality if patients undergo surgery before the onset of advanced heart failure symptoms. Late mortality is associated with a high preoperative Charlson index, short right index of myocardial performance ratio, and advanced New York Heart Association class.
Effect of Renal Sympathetic Denervation on Glucose Metabolism in Patients With Resistant Hypertension
Authors: Mahfoud Felix , Schlaich Markus , Kindermann Ingrid , Ukena Christian , Cremers Bodo , Brandt Mathias C. , Hoppe Uta C. , Vonend Oliver , Rump Lars C. , Sobotka Paul A. , Krum Henry , Esler Murray , Böhm Michael
Published: April 2011

Background—

Hypertension is associated with impaired glucose metabolism and insulin resistance. Chronic activation of the sympathetic nervous system may contribute to either condition. We investigated the effect of catheter-based renal sympathetic denervation on glucose metabolism and blood pressure control in patients with resistant hypertension.

Methods and Results—

We enrolled 50 patients with therapy-resistant hypertension. Thirty-seven patients underwent bilateral catheter-based renal denervation, and 13 patients were assigned to a control group. Systolic and diastolic blood pressures, fasting glucose, insulin, C peptide, hemoglobin A
1c
, calculated insulin sensitivity (homeostasis model assessment–insulin resistance), and glucose levels during oral glucose tolerance test were measured before and 1 and 3 months after treatment. Mean office blood pressure at baseline was 178/96±3/2 mm Hg. At 1 and 3 months, office blood pressure was reduced by −28/−10 mm Hg (
P
<0.001) and −32/−12 mm Hg (
P
<0.001), respectively, in the treatment group, without changes in concurrent antihypertensive treatment. Three months after renal denervation, fasting glucose was reduced from 118±3.4 to 108±3.8 mg/dL (
P
=0.039). Insulin levels were decreased from 20.8±3.0 to 9.3±2.5 μIU/mL (
P
=0.006) and C-peptide levels from 5.3±0.6 to 3.0±0.9 ng/mL (
P
=0.002). After 3 months, homeostasis model assessment–insulin resistance decreased from 6.0±0.9 to 2.4±0.8 (
P
=0.001). Additionally, mean 2-hour glucose levels during oral glucose tolerance test were reduced significantly by 27 mg/dL (
P
=0.012). There were no significant changes in blood pressure or metabolic markers in the control group.

Conclusions—

Renal denervation improves glucose metabolism and insulin sensitivity in addition to a significantly reducing blood pressure. However, this improvement appeared to be unrelated to changes in drug treatment. This novel procedure may therefore provide protection in patients with resistant hypertension and metabolic disorders at high cardiovascular risk.

Clinical Trial Registration—

URL:
http://www.ClinicalTrials.gov
. Unique identifiers: NCT00664638 and NCT00888433.
Expression of Placental
FLT1
Transcript Variants Relates to Both Gestational Hypertensive Disease and Fetal Growth
Authors: Jebbink Jiska , Keijser Remco , Veenboer Geertruda , van der Post Joris , Ris-Stalpers Carrie , Afink Gijs
Published: April 2011

The recent discovery of additional alternative spliced
FLT1
transcripts encoding novel soluble (s)FLT1 protein isoforms complicates both the predictive value and functional implications of sFLT1 in preeclampsia. We investigated
FLT1
expression levels and splicing patterns in placentas of normotensive and preeclamptic women, and established the tissue specificity of all
FLT1
transcript variants. mRNA levels of
sFLT1
splice variants were determined by real-time polymerase chain reaction in 21 normal human tissues and placental biopsies from 91 normotensive and 55 preeclamptic women. Cellular localization of placental
FLT1
expression was established by RNA in situ hybridization. Of all tissues investigated, placenta has by far the highest
FLT1
mRNA expression level, mainly localized in the syncytiotrophoblast layer. More than 80% of placental transcripts correspond to
sFLT1_v2
. Compared with normotensive placenta, preeclamptic placenta has ≈3-fold higher expression of all
FLT1
transcript variants (
P
<0.001), with a slight shift in favor of
sFLT1_v1
. Although to a lesser degree, transcript levels are also increased in placenta from normotensive women that deliver a small for gestational age neonate. We conclude that sFLT isoform–specific assays could potentially improve the accuracy of current sFLT1 assays for the prediction of preeclampsia. However, placental
FLT1
transcript levels are increased not only in preeclampsia but also in normotensive pregnancy with a small for gestational age fetus. This may indicate a common pathway involved in the development of both conditions but complicates the use of circulating sFLT1 protein levels for the prediction or diagnosis of preeclampsia alone.
Role of Asymmetrical Dimethylarginine in Inflammation-Induced Endothelial Dysfunction in Human Atherosclerosis
Authors: Antoniades Charalambos , Demosthenous Michael , Tousoulis Dimitris , Antonopoulos Alexios S. , Vlachopoulos Charalambos , Toutouza Marina , Marinou Kyriakoula , Bakogiannis Constantinos , Mavragani Kleio , Lazaros George , Koumallos Nikolaos , Triantafyllou Costas , Lymperiadis Dimitris , Koutsilieris Michael , Stefanadis Christodoulos
Published: April 2011

We explored the role of asymmetrical dimethylarginine (ADMA) as a cause of endothelial dysfunction induced by systemic inflammation. In vitro data suggest that ADMA bioavailability is regulated by proinflammatory stimuli, but it is unclear whether ADMA is a link between inflammation and endothelial dysfunction in humans. In study 1 we recruited 351 patients with coronary artery disease (CAD) and 87 healthy controls. In study 2 we recruited 69 CAD, 69 healthy, and 10 patients with rheumatoid arthritis, whereas in study 3, 22 healthy and 70 CAD subjects were randomly assigned to
Salmonella typhii
vaccination (n=11 healthy and n=60 CAD) or placebo (n=11 healthy and n=10 CAD). Circulating interleukin 6/ADMA and flow-mediated dilation (FMD) were measured at 0 and 8 hours. In study 1, ADMA was inversely correlated with FMD in healthy individuals and CAD patients (
P
<0.0001 for both). However, interleukin 6 was inversely correlated with FMD (
P
<0.0001) in healthy subjects but not in CAD patients. The positive correlation between ADMA and interleukin 6 was stronger in healthy (
r
=0.515;
P
<0.0001) compared with CAD (
r
=0.289;
P
=0.0001) subjects. In study 2, both patients with rheumatoid arthritis and CAD had higher interleukin 6 (
P
<0.0001) and ADMA (
P
=0.004) but lower FMD (
P
=0.001) versus healthy subjects. In study 3, vaccination increased interleukin 6 in healthy (
P
<0.001) and CAD (
P
<0.001) subjects. FMD was reduced in healthy subjects (
P
<0.05), but its reduction in CAD was borderline. Vaccination increased ADMA only in healthy subjects (
P
<0.001). Systemic, low-grade inflammation leads to increased ADMA that may induce endothelial dysfunction. This study demonstrated that ADMA may be a link between inflammation and endothelial dysfunction in humans.
Distributed Control of Uncertain Systems Using Superpositions of Linear Operators
Authors: Sanger Terence D.
Published: April 2011

Control in the natural environment is difficult in part because of uncertainty in the effect of actions. Uncertainty can be due to added motor or sensory noise, unmodeled dynamics, or quantization of sensory feedback. Biological systems are faced with further difficulties, since control must be performed by networks of cooperating neurons and neural subsystems. Here, we propose a new mathematical framework for modeling and simulation of distributed control systems operating in an uncertain environment. Stochastic differential operators can be derived from the stochastic differential equation describing a system, and they map the current state density into the differential of the state density. Unlike discrete-time Markov update operators, stochastic differential operators combine linearly for a large class of linear and nonlinear systems, and therefore the combined effects of multiple controllable and uncontrollable subsystems can be predicted. Design using these operators yields systems whose statistical behavior can be specified throughout state-space. The relationship to Bayesian estimation and discrete-time Markov processes is described.
A Simple Derivation of a Bound on the Perceptron Margin Using Singular Value Decomposition
Authors: Barak Omri , Rigotti Mattia
Published: April 2011

The perceptron is a simple supervised algorithm to train a linear classifier that has been analyzed and used extensively. The classifier separates the data into two groups using a decision hyperplane, with the margin between the data and the hyperplane determining the classifier's ability to generalize and its robustness to input noise. Exact results for the maximal size of the separating margin are known for specific input distributions, and bounds exist for arbitrary distributions, but both rely on lengthy statistical mechanics calculations carried out in the limit of infinite input size. Here we present a short analysis of perceptron classification using singular value decomposition. We provide a simple derivation of a lower bound on the margin and an explicit formula for the perceptron weights that converges to the optimal result for large separating margins.
Asymptotic Convergence Properties of the EM Algorithm for Mixture of Experts
Authors: Yang Yan , Ma Jinwen
Published: April 2011

Mixture of experts (ME) is a modular neural network architecture for supervised classification. The double-loop expectation-maximization (EM) algorithm has been developed for learning the parameters of the ME architecture, and the iteratively reweighted least squares (IRLS) algorithm and the Newton-Raphson algorithm are two popular schemes for learning the parameters in the inner loop or gating network. In this letter, we investigate asymptotic convergence properties of the EM algorithm for ME using either the IRLS or Newton-Raphson approach. With the help of an overlap measure for the ME model, we obtain an upper bound of the asymptotic convergence rate of the EM algorithm in each case. Moreover, we find that for the Newton approach as a specific Newton-Raphson approach to learning the parameters in the inner loop, the upper bound of asymptotic convergence rate of the EM algorithm locally around the true solution Θ* is [Formula: see text], where ϵ>0 is an arbitrarily small number, o(x) means that it is a higher-order infinitesimal as x → 0, and e(Θ*) is a measure of the average overlap of the ME model. That is, as the average overlap of the true ME model with large sample tends to zero, the EM algorithm with the Newton approach to learning the parameters in the inner loop tends to be asymptotically superlinear. Finally, we substantiate our theoretical results by simulation experiments.
A Regularized Correntropy Framework for Robust Pattern Recognition
Authors: He Ran , Zheng Wei-Shi , Hu Bao-Gang , Kong Xiang-Wei
Published: April 2011

This letter proposes a new multiple linear regression model using regularized correntropy for robust pattern recognition. First, we motivate the use of correntropy to improve the robustness of the classical mean square error (MSE) criterion that is sensitive to outliers. Then an l1 regularization scheme is imposed on the correntropy to learn robust and sparse representations. Based on the half-quadratic optimization technique, we propose a novel algorithm to solve the nonlinear optimization problem. Second, we develop a new correntropy-based classifier based on the learned regularization scheme for robust object recognition. Extensive experiments over several applications confirm that the correntropy-based l1 regularization can improve recognition accuracy and receiver operator characteristic curves under noise corruption and occlusion.
Firing Variability Is Higher than Deduced from the Empirical Coefficient of Variation
Authors: Ditlevsen Susanne , Lansky Petr
Published: April 2011

A convenient and often used summary measure to quantify the firing variability in neurons is the coefficient of variation (CV), defined as the standard deviation divided by the mean. It is therefore important to find an estimator that gives reliable results from experimental data, that is, the estimator should be unbiased and have low estimation variance. When the CV is evaluated in the standard way (empirical standard deviation of interspike intervals divided by their average), then the estimator is biased, underestimating the true CV, especially if the distribution of the interspike intervals is positively skewed. Moreover, the estimator has a large variance for commonly used distributions. The aim of this letter is to quantify the bias and propose alternative estimation methods. If the distribution is assumed known or can be determined from data, parametric estimators are proposed, which not only remove the bias but also decrease the estimation errors. If no distribution is assumed and the data are very positively skewed, we propose to correct the standard estimator. When defining the corrected estimator, we simply use that it is more stable to work on the log scale for positively skewed distributions. The estimators are evaluated through simulations and applied to experimental data from olfactory receptor neurons in rats.
New Method to Measure End-to-End Delay of Virtual Reality
Authors: Di Luca Massimiliano
Published: April 2011

A virtual reality (VR) system tracks one or more objects to generate the depiction of a virtual environment from the user's vantage point. No system achieves this instantaneously: changes in the depicted virtual environment are delayed from changes in the position of the objects being tracked. In this paper, a method is proposed to quantify this time difference, the end-to-end delay of the VR system. Two light-sensing devices and two luminance gradients are used to simultaneously encode the position of one tracked object and its virtual counterpart. One light-sensing device is attached to the tracked object and it captures light from the gradient in the physical environment. The other device captures light from the gradient in the virtual environment. A measurement is obtained by moving the tracked object repetitively (by hand) across the gradient. The end-to-end delay is the asynchrony between the signals generated by the two light-sensing devices. The results collected with oscillatory movements performed at different frequencies indicate that for some VR systems, the end-to-end delay might not be constant but could vary as a function of the oscillation frequency.
Perceived Digital Game Realism: A Quantitative Exploration of its Structure
Authors: Ribbens Wannes , Malliet Steven
Published: April 2011

A quantitative exploration is presented of the concept of perceived digital game realism, based upon the frameworks described by Malliet (2006), and Shapiro, Peña-Herborn, and Hancock (2006). The concepts and categories outlined in both studies are complemented with an additional literature study and subjected to an exploratory factor analysis. Principal axis factoring was performed on items completed by 385 respondents whose ages ranged between 15 and 19 years. Seven factors of perceived game realism were identified: simulation, freedom of choice, character involvement, perceptual pervasiveness, authenticity regarding subject matter, authenticity regarding characters, and social realism. These findings are to a considerable extent congruent with the theoretical framework.
Does Virtual Reality Enhance Exercise Performance, Enjoyment, and Dissociation? An Exploratory Study on a Stationary Bike Apparatus
Authors: Mestre Daniel R. , Dagonneau Virginie , Mercier Charles-Symphorien
Published: April 2011

The present study aimed at testing the general assumption that virtual reality can enhance the experience of exercising. More specifically, we tested the effects of sensory input (music and video feedback) during physical training on performance, enjoyment, and attentional focus by means of a computerized ergometer coupled with VR software. Twelve university students participated in the study. The experimental procedure consisted in a 2 × 3 × 4 mixed design, with two types of feedback (video feedback vs. video feedback and music), three course phases (e.g., flat, uphill, and downhill) and four sessions (task repetition). The virtual feedback was a video film of the course that participants had to complete. Video display speed was proportional to the participant's pedaling speed. Force feedback, applied to the real bicycle wheel, was proportional to the instantaneous course slope. The results showed a positive effect of task repetition on participants' performance only when video feedback was associated with listening to music. In an attempt to objectively assess attentional focus, we analyzed participants' gaze orientation. Gaze analysis showed a reduction in the time spent gazing at video feedback across sessions. Associating video feedback with freely chosen music led to a differential use of video feedback as a function of exercise intensity. Finally, sensory stimulation appeared to have a dissociative role on participants' attentional focus during exercise, but adding music listening to video feedback appears to be necessary to maintain (long term) the participants' commitment to the task. The results are discussed in terms of the functional status of sensory stimulation during exercise, and its interactions with exercise intensity, participants' performance, and attentional focus. They also suggest that gaze analysis is one promising way to access attention allocation and its relationships with performance.
Visual and Auditory Augmented Concurrent Feedback in a Complex Motor Task
Authors: Sigrist Roland
Published: April 2011

In general, concurrent augmented feedback has been shown to effectively enhance learning in complex motor tasks. However, to optimize technical systems that are intended to reinforce motor learning, a systematic evaluation of different augmented feedback designs is required. Until now, mainly visual augmented feedback has been applied to enhance learning of complex motor tasks. Since most complex motor tasks are mastered in response to information visually perceived, providing augmented concurrent feedback in a visual manner may overload the capacities of visual perception and cognitive processing. Thus, the aim of this work was to evaluate the practicability of auditory feedback designs supporting a three-dimensional rowing-type movement in comparison with visual feedback designs. We term a feedback design practical if the provided information can easily be perceived and interpreted, and immediately be used to support the movement. In a first experiment, it became evident that participants could interpret three-dimensional auditory feedback designs based on stereo balance, pitch, timbre, and/or volume. Eleven of 12 participants were able to follow the different target movements using auditory feedback designs as accurately as with a very abstract visual feedback design. Visual designs based on superposition of actual and target oar orientation led to the most accurate performance.

Considering the first experimental results, the feedback designs were further developed and again evaluated. It became evident that a permanent visual display of the target trajectories could further enhance movement accuracy. Moreover, results indicated that the practicability of the auditory designs depends on the polarity of the mapping functions. In general, both visual and auditory concurrent feedback designs were practical to immediately support multidimensional movement. In a next step, the effectiveness to enhance motor learning will be systematically evaluated.
The Short-Term Effects of Real-Time Virtual Reality Feedback on Motor Learning in Dance
Authors: Eaves Daniel L. , Breslin Gavin , van Schaik Paul
Published: April 2011

Does virtual reality (VR) represent a useful platform for teaching real-world motor skills? In domains such as sport and dance, this question has not yet been fully explored. The aim of this study was to determine the effects of two variations of real-time VR feedback on the learning of a complex dance movement. Novice participants (n = 30) attempted to learn the action by both observing a video of an expert's movement demonstration and physically practicing under one of three conditions. These conditions were: full feedback (FULL-FB), which presented learners with real-time VR feedback on the difference between 12 of their joint center locations and the expert's movement during learning; reduced feedback (REDUCED-FB), which provided feedback on only four distal joint center locations (end-effectors); and no feedback (NO-FB), which presented no real-time VR feedback during learning. Participants' kinematic data were gathered before, immediately after, and 24 hr after a motor learning session. Movement error was calculated as the difference in the range of movement at specific joints between each learner's movement and the expert's demonstrated movement. Principal component analysis was also used to examine dimensional change across time. The results showed that the REDUCED-FB condition provided an advantage in motor learning over the other conditions: it achieved a significantly greater reduction in error across five separate error measures. These findings indicate that VR can be used to provide a useful platform for teaching real-world motor skills, and that this may be achieved by its ability to direct the learner's attention to the key anatomical features of a to-be-learned action.
Astrojumper: Motivating Exercise with an Immersive Virtual Reality Exergame
Authors: Finkelstein Samantha , Suma Evan A.
Published: April 2011

We present the design and evaluation of Astrojumper, an immersive virtual reality exergame developed to motivate players to engage in rigorous, full-body exercise. We performed a user study with 30 people between the ages of 6 and 50 who played the game for 15 min. Regardless of differences in age, gender, activity level, and video game experience, participants rated Astrojumper extremely positively and experienced a significant increase in heart rate after gameplay. Additionally, we found that participants' ratings of perceived workout intensity positively correlated with their level of motivation. Overall, our results demonstrate that Astrojumper effectively motivates both children and adults to exercise through immersive virtual reality technology and a simple, yet engaging, game design.
Virtual Reality as a Tool for the Study of Perception-Action: The Case of Running to Catch Fly Balls
Authors: Zaal Frank T. J. M. , Bootsma Reinoud J.
Published: April 2011

Virtual reality (VR) holds great promise for the study of perception-action. The case of studying the outfielder problem is presented as an example of how VR has contributed to our understanding of perception-action, and of the potential and pitfalls of using VR in such a task. The outfielder problem refers to the situation in a baseball game (and analogous situations) in which an outfielder has to run to get to the right location at the right time to make a catch. Several experimental studies are discussed in which participants had to intercept real or virtual balls. The biggest added value of using VR is the fact that the virtual world is completely in the hands of the experimenter, which allows studying situations that do not exist outside of VR, thus enabling strong hypothesis testing. A number of factors related to the success of the VR experiments are identified, such as the lack of haptic feedback in VR setups used in this paradigm until now, the specifics of the optics presented to the participants, and the available space for locomotion. We argue that it is important to make a close comparison of task behavior in VR with that outside of VR, but conclude having great expectations of the role of VR in perception-action research.
Seasonal Modes of Surface Cooling in the Gulf of Guinea
Authors: Jouanno Julien , Marin Frédéric , du Penhoat Yves , Molines Jean Marc , Sheinbaum Julio
Published: April 2011

A numerical simulation of the tropical Atlantic Ocean indicates that surface cooling in upwelling zones of the Gulf of Guinea is mostly due to vertical mixing. At the seasonal scale, the spatial structure and the time variability of the northern and southern branches of the South Equatorial Current (SEC), and of the Guinea Current, are correlated with the timing and distribution of turbulent heat fluxes in the Gulf of Guinea. Through modulation of the velocity shear at the subsurface, these surface currents control the vertical turbulent exchanges, bringing cold and nutrient-rich waters to the surface. This mechanism explains the seasonality and spatial distribution of surface chlorophyll concentrations better than the generally accepted hypothesis that thermocline movements control the nutrient flux. The position of the southern SEC explains why the cold tongue and high chlorophyll concentrations extend from the equator to 4°S in the southeastern part of the basin.
Development and Application of a Compact, Tunable, Solid-State Airborne Ozone Lidar System for Boundary Layer Profiling
Authors: Alvarez R. J. , Senff C. J. , Langford A. O. , Weickmann A. M. , Law D. C. , Machol J. L. , Merritt D. A. , Marchbanks R. D. , Sandberg S. P. , Brewer W. A. , Hardesty R. M. , Banta R. M.
Published: April 2011

The National Oceanic and Atmospheric Administration/Earth System Research Laboratory/Chemical Sciences Division (NOAA/ESRL/CSD) has developed a versatile, airborne lidar system for measuring ozone and aerosols in the boundary layer and lower free troposphere. The Tunable Optical Profiler for Aerosol and Ozone (TOPAZ) lidar was deployed aboard a NOAA Twin Otter aircraft during the Texas Air Quality Study (TexAQS 2006) and the California Research at the Nexus of Air Quality and Climate Change (CalNex 2010) field campaigns. TOPAZ is capable of measuring ozone concentrations in the lower troposphere with uncertainties of several parts per billion by volume at 90-m vertical and 600-m horizontal resolution from an aircraft flying at 60 m s−1. The system also provides uncalibrated aerosol backscatter profiles at 18-m vertical and 600-m horizontal resolution. TOPAZ incorporates state-of-the-art technologies, including a cerium-doped lithium calcium aluminum fluoride (Ce:LiCAF) laser, to make it compact and lightweight with low power consumption. The tunable, three-wavelength UV laser source makes it possible to optimize the wavelengths for differing atmospheric conditions, reduce the interference from other atmospheric constituents, and implement advanced analysis techniques. This paper describes the TOPAZ lidar, its components and performance during testing and field operation, and the data analysis procedure, including a discussion of error sources. The performance characteristics are illustrated through a comparison between TOPAZ and an ozonesonde launched during the TexAQS 2006 field campaign. A more comprehensive set of comparisons with in situ measurements during TexAQS 2006 and an assessment of the TOPAZ accuracy and precision are presented in a companion paper.
Temporal–Spatial Distribution of Atmospheric Predictability Limit by Local Dynamical Analogs
Authors: Li Jianping , Ding Ruiqiang
Published: April 2011

To quantify the predictability limit of a chaotic system, the authors recently developed a method using the nonlinear local Lyapunov exponent (NLLE). The NLLE method provides a measure of local predictability limit of chaotic systems and is intended to supplement existing predictability methods. To apply the NLLE in studies of actual atmospheric predictability, an algorithm based on local dynamical analogs is devised to enable the estimation of the NLLE and its derivatives using experimental or observational data. Two examples are given to illustrate the effectiveness of the algorithm, involving the Lorenz63 three-variable model and the Lorenz96 forty-variable model; they reveal that the algorithm is applicable in estimating the NLLE of a chaotic system from its experimental time series. On this basis, the NLLE method is used to investigate temporal–spatial distributions of predictability limits of the daily geopotential height and wind fields. The limit of atmospheric predictability varies widely with region, altitude, and season. The predictability limits of the daily geopotential height and wind fields are generally less than 3 weeks in the troposphere, whereas they are approximately 1 month in the lower stratosphere, revealing a potential predictability source for forecasting weather from the stratosphere. Further work is required to examine broader applications of the NLLE method in predictability studies of the atmosphere, ocean, and other systems.
Older LGBT people’s care networks and communities of practice: A brief note
Authors: Hughes Mark , Kentlyn Sue
Published: April 2011

This article critically examines literature relating to the care of older lesbian, gay, bisexual and transgender (LGBT) people. It promotes an analysis of the network context of this care and advocates the use of the concept of ‘communities of practice’ to understand the processes of network participation and identity negotiation.
Population aging and social work practice with older adults: Demographic and policy challenges
Authors: Crampton Alexandra
Published: April 2011

Living into older ages is changing from an exceptional to an expected part of the life course experience worldwide. Improvement in health and longevity across the lifespan also brings challenges for social work practice. At the same time, these changes are part of population aging trends that are not universal or inevitable. In addition, population aging discourse often reduces the complex dynamics of population aging to a problematic rise in older adults characterized as unproductive and dependent. Social workers can challenge the ageist construction of older adults by using our contextualized knowledge of how people age in their social environments.
The meaning of community-based care for frail Mexican American elders
Authors: Donlan William 'Ted'
Published: April 2011

A qualitative, collective case study research design integrated in-depth interviewing and participant observation to identify how a theoretically sampled collection of frail Mexican American elders socially constructed the meaning of community-based care they received. Analysis revealed extensive variance in how Mexican American cultural identity systems attribute meaning to the eldercare context. The strong intertwined presence of cultural themes involving Latino/Hispanic familism, gender identity constructs, and religious belief systems demonstrated the importance for service providers to take minority cultures into consideration in the development of more consumer-directed eldercare policies and programs.
Political Institutions and Street Protests in Latin America
Authors: Machado Fabiana , Scartascini Carlos , Tommasi Mariano
Published: April 2011

In this article, the authors argue that where institutions are strong, actors are more likely to participate in the political process through institutionalized arenas, while where they are weak, protests and other unconventional means of participation become more appealing. The authors explore this relationship empirically by combining country-level measures of institutional strength with individual-level information on protest participation in seventeen Latin American countries. The authors find evidence that weaker political institutions are associated with a higher propensity to use alternative means for expressing preferences, that is, to protest.
A Synthesis of Read-Aloud Interventions on Early Reading Outcomes Among Preschool Through Third Graders at Risk for Reading Difficulties
Authors: Swanson Elizabeth , Vaughn Sharon , Wanzek Jeanne , Petscher Yaacov , Heckert Jennifer , Cavanaugh Christie , Kraft Guliz , Tackett Kathryn
Published: April 2011

A synthesis and meta-analysis of the extant research on the effects of storybook read-aloud interventions for children at risk for reading difficulties ages 3 to 8 is provided. A total of 29 studies met criteria for the synthesis, with 18 studies providing sufficient data for inclusion in the meta-analysis. Read-aloud instruction has been examined using dialogic reading; repeated reading of stories; story reading with limited questioning before, during, and/or after reading; computer-assisted story reading; and story reading with extended vocabulary activities. Significant, positive effects on children’s language, phonological awareness, print concepts, comprehension, and vocabulary outcomes were found. Despite the positive effects for read-aloud interventions, only a small amount of outcome variance was accounted for by intervention type.
A Meta-Analysis of the RTI Literature for Children at Risk for Reading Disabilities
Authors: Tran Loan , Sanchez Tori , Arellano Brenda , Lee Swanson H.
Published: April 2011

This article synthesizes the literature comparing at-risk children designated as responders and low responders to interventions in reading. The central question addressed in this review is whether individual differences in reading-related skills at pretest predict responders at posttest across a variety of interventions and sets of criteria for determining responding and low responding. A total of 13 studies met criteria for the meta-analysis, yielding 107 weighted effect sizes (ESs) at posttest ( M = .76, SE = .03, 95% confidence interval [CI] =.71, .81) and 108 weighted ESs at pretest ( M = 1.02, SE = .03, CI = 1.02, 1.13). The results showed that the magnitude of ES between responders and low responders increased from pretest to posttest on measures of reading (e.g., real word identification = 1.06 vs. 1.53, word attack = 1.10 vs. 1.28, and passage comprehension, 0.45 vs. 1.43). Hierarchical linear modeling indicated that overall posttest ESs were significantly moderated by pretest scores as well as the type of measure administered, whereas no significant moderating effects were found for number of weeks of intervention, length of sessions, number of sessions, type of intervention (one-to-one vs. small group instruction), and criteria for defining responders (cutoff, scores, discrepancy, benchmark). Overall, the synthesis suggested that regardless of type of treatment and identification criteria, response-to-intervention (RTI) conditions were not effective in mitigating learner characteristics related to pretest conditions.
Determining the Authenticity of Suicide Notes
Authors: Bennell Craig , Jones Natalie J. , Taylor Alyssa
Published: April 2011

Two studies examined the degree to which training could improve participants’ ability to determine the authenticity of suicide notes. In Study 1, informing participants about variables that are known to discriminate between genuine and simulated suicide notes did not improve their decision accuracy beyond chance, nor did this training allow participants to perform as accurately as a statistical prediction rule. In Study 2, the provision of additional training instructions did enhance participants’ decision accuracy but not to a level achieved by the statistical prediction rule. However, training that included all instructions simultaneously resulted in a slight performance decrease attributable to the fact that certain instructions proved problematic when applied to the sample of suicide notes upon which decisions were being made. The potential implications of these findings for police decision making and training are discussed.
Are Social Value Orientations Expressed Automatically? Decision Making in the Dictator Game
Authors: Cornelissen Gert , Dewitte Siegfried , Warlop Luk
Published: April 2011

Drawing on the social intuitionist model, the authors studied the hypothesis that social value orientations are expressed automatically in behavior. They compared spontaneous and more deliberated decisions in the dictator game and confirmed that social values determine behavior when responses are based on the automatic system. By means of both mediation and experimental analyses, the authors further demonstrate that the automatic expression of social value orientations is mediated by perceptions of interpersonal closeness. A reasoning process can subsequently override these automatic responses and disconnect decisions from perceptions of interpersonal closeness. This results in lower levels of other-regarding behavior, at least for prosocials.