bluuebunny/crossref_metadata_2025 huggingface dataset:
Is There a (Viable) Crucial-Case Method?
Authors: Gerring John
Published: February 2007

Case study researchers use diverse methods to select their cases, a matter that has elicited considerable comment and no little consternation. Of all these methods, perhaps the most controversial is the crucial-case method, first proposed by Harry Eckstein several decades ago. Since Eckstein’s influential essay, the crucial-case approach has been used in a multitude of studies across several social science disciplines and has come to be recognized as a staple of the case study method. Yet the idea of any single case playing a crucial (or critical) role is not widely accepted. In this article, the method of the crucial case is explored, and a limited defense (somewhat less expansive than that envisioned by Eckstein) of that method is undertaken. A second method of case-selection, closely associated with the logic of the crucial case, is introduced: the pathway case.
Democratization and Economic Liberalization in the Postcommunist World
Authors: Fish M. Steven , Choudhry Omar
Published: February 2007

How does economic liberalization affect political regime? Economic liberalization is widely regarded as inimical to democratization. The “Washington Consensus,” which generally endorses “shock therapy” and envisions a basic compatibility between economic liberalization and democratization, is widely disdained in social science. Many scholars hold that neoliberal economics depresses popular living standards and exacerbates socioeconomic inequalities, thereby compromising democratization. Focusing on the postcommunist region, this article tests this hypothesis. It examines the data that have been used to assess the relationship between economic liberalization and political democratization and presents analyses using more appropriate and differentiated techniques. The authors find that economic liberalization advances rather than undermines democratization. Using Engle-Granger analysis, they find that although economic liberalization has no discernible impact on democratization in the short term, democratization adjusts in the direction of a long-term equilibrium to which economic liberalization contributes substantially.
The Gospel of Judas
Authors: Gathercole Simon
Published: February 2007

This article gives a brief account of the literature already produced on the recently published Gospel of Judas, and of the manuscript’s character and contents. A discussion of the work’s historical and theological relevance shows that while this new ‘Gospel’ does not provide any reliable information about the historical figures of Jesus and Judas, it does nevertheless afford a fascinating glimpse into the conflicts between Christianity and Gnosticism in the second century.
Resource conservation as a basis for the mutual exclusivity effect in children's word learning
Authors: Piccin Thomas B. , Blewitt Pamela
Published: February 2007

The tendency of children to apply a novel label to a novel object rather than to a familiar one, or to resist applying multiple labels to the same object, has often been interpreted as evidence of a ‘mutual exclusivity’ constraint on word learning. We offer evidence that the mutual exclusivity effect is not specific to word learning but is rooted in a tendency to conserve general cognitive resources. In the current research, 3-year-olds learned and produced two different novel labels for the same object when doing so allowed them to maximize their reward. However, when producing multiple labels afforded no apparent benefit, children tended to produce a single label. An identical pattern of responses was seen in a parallel non-word learning task. These results suggest that, to some extent, conservation of cognitive resources may play a role in the mutual exclusivity effect seen in word learning.
Qualitative aspects of productive vocabulary at the 200-and 500-word stages: A comparison between spontaneous speech and parental report data
Authors: Salerni Nicoletta , Assanelli Alessandra , D'Odorico Laura , Rossi Germano
Published: February 2007

This paper compares the proportions of different word classes present in 30 Italian children at two specific stages of vocabulary development (200 and 500 words). The Italian version of the MacArthur Communicative Development Inventory and spontaneous speech samples produced during an observation session were both used to examine the extent to which these children produce quantitatively different vocabulary compositions. Both methods revealed a greater presence of nouns than other word classes in the sample studied, although significant differences were found in the noun/other word class proportions.
The Physiology of Incretin Hormones and the Basis for DPP-4 Inhibitors
Authors: McKennon Skye Aiko , Campbell R. Keith
Published: February 2007

With the rising prevalence of diabetes, new therapies that provide glucose control are needed. Although many medications are available, tight glucose control is still a challenge. In this article, the physiology of glucose home-ostasis is explored with respect to type 2 diabetes. The incretin effect is explained in detail, and the incretin hormones, glucose-dependent insulinotrophic polypeptide and glucagon-like peptide 1, are investigated as well as their contribution to type 2 diabetes therapy. Studies involving dipeptidyl-peptidase 4 (DPP-4) inhibitors are summarized as to their effects on glucose homeostasis. Specifically, vildagliptin (Galvus®; Novartis International AG, Basel, Switzerland) and sitagliptin (Januvia™; Merck & Co, Inc, Whitehouse Station, NJ) are described. The use and efficacy of the currently available incretin mimetic, exenatide (Byetta®; Amylin Pharmaceuticals, Inc and Eli Lilly and Company, San Diego, Calif, and Indianapolis, Ind), are briefly discussed. Throughout this article, the rationale for the use of DPP-4 inhibitors is presented.
Ulnar Collateral Ligament Reconstruction in Major League Baseball Pitchers
Authors: Gibson Brett W. , Webner David , Huffman G. Russell , Sennett Brian J.
Published: February 2007

Background

Ulnar collateral ligament reconstruction is commonly performed in major league pitchers, but little is known about pitching performance after a return to major league play.

Hypothesis

Pitching performance after ulnar collateral ligament reconstruction returns to baseline by the second season after surgery.

Study Design

Cohort study (prognosis); Level of evidence, 2.

Methods

Data were reviewed for 68 major league pitchers who pitched in at least 1 major league game before undergoing ulnar collateral ligament reconstruction between 1998 and 2003. Mean innings pitched per season, earned run average, and walks and hits per inning pitched were compared for each major league pitcher before and after surgery. All demographic and performance variables were analyzed for an association with ulnar collateral ligament insufficiency and a successful return to major league play.

Results

Fifty-six (82%) pitchers returned to major league play at a mean of 18.5 months after surgery with no significant change in mean earned run average or walks and hits per inning pitched. The mean innings pitched per season was not statistically different from controls by the second season after surgery. Starting pitchers demonstrated a higher risk of ulnar collateral ligament injury requiring reconstruction. More experienced pitchers and those with a higher earned run average were less likely to require ulnar collateral ligament reconstruction. No factors predictive of a successful return to play were identified.

Conclusion

Most major league pitchers return from ulnar collateral ligament reconstruction by the second season after surgery with no statistical change in mean innings pitched, earned run average, or walks and hits per inning pitched from preinjury levels.
Pain Relief through an Antinociceptive Effect after Radiofrequency Application
Authors: Takahashi Norimasa , Tasto James P. , Ritter Mark , Ochiai Nobuyasu , Ohtori Seiji , Moriya Hideshige , Amiel David
Published: February 2007

Background

Many patients with chronic tendinosis have experienced early pain relief after application of bipolar radiofrequency treatment. Pathologic nerve ingrowth or nerve irritation in the tendon has been considered as a possible cause of the pain experienced with tendinosis.

Hypothesis

Bipolar radiofrequency treatment will ablate nerve fibers, resulting in pain relief.

Study Design

Controlled laboratory study.

Methods

Eighteen Sprague-Dawley rats were used in this study. Eight rats were treated with 2 points of bipolar radiofrequency applications applied to the hind paws with the Topaz microdebrider device, 6 sham rats had a needle applied to the hind paws, and there were 4 control rats. Tissues were processed for neural class III β-tubulin (TUJ-1) or calcitonin gene-related peptide (CGRP) immunohistochemistry by using the free-floating avidin-biotin complex technique. The numbers of TUJ1-immunoreactive and CGRP-immunoreactive nerve fibers in the epidermis were counted and compared with sham and control.

Results

The number of nerve fibers demonstrated by both the antibodies of TUJ1 and CGRP were significantly decreased (P = .0002-.002) during the first 2 weeks after bipolar radiofrequency treatment. Macroscopically, the foot pad showed 2 dimples on the surface after bipolar radiofrequency treatment. Although it still showed a scar after 7 days, after 14 days it looked no different than the untreated contralateral control foot pad and foot pad of the sham group.

Conclusion

Bipolar radiofrequency treatment induced acute degeneration and/or ablation of sensory nerve fibers.

Clinical Relevance

Degeneration or ablation of nerve fibers after bipolar radiofrequency treatment may explain the early postoperative pain relief after microtenotomy for tendinosis.
The Effects of Core Proprioception on Knee Injury
Authors: Zazulak Bohdanna T. , Hewett Timothy E. , Reeves N. Peter , Goldberg Barry , Cholewicki Jacek
Published: February 2007

Background

In sports involving pivoting and landing, female athletes suffer knee injury at a greater rate than male athletes.

Hypotheses

Proprioceptive deficits in control of the body's core may affect dynamic stability of the knee. Female, but not male, athletes who suffered a knee injury during a 3-year follow-up period would demonstrate decreased core proprioception at baseline testing as compared with uninjured athletes.

Study Design

Cohort study (prognosis); Level of evidence, 2.

Methods

Study subjects were 277 collegiate athletes (140 female, 137 male) who were prospectively tested for core proprioception by active and passive proprioceptive repositioning. Athletes were monitored for injury for 3 years. An ANOVA and multivariate logistic regression were used to test whether core proprioception was related to knee injuries in athletes.

Results

Twenty-five athletes sustained knee injuries (11 women, 14 men). Deficits in active proprioceptive repositioning were observed in women with knee injuries (2.2°) and ligament/meniscal injuries (2.4°) compared with uninjured women (1.5°, P ≤ .05). There were no differences in average active proprioceptive repositioning error between injured men and uninjured men (P ≥ .05). Uninjured women demonstrated significantly less average error in active proprioceptive repositioning than uninjured men (1.5° vs 1.7°, P ≤ .05). For each degree increase in average active proprioceptive repositioning error, a 2.9-fold increase in the odds ratio of knee injury was observed, and a 3.3-fold increase in odds ratio of ligament/meniscal injury was observed (P ≤ .01). Active proprioceptive repositioning predicted knee injury status with 90% sensitivity and 56% specificity in female athletes.

Conclusions

Impaired core proprioception, measured by active proprioceptive repositioning of the trunk, predicted knee injury risk in female, but not male, athletes.
Assessing the Working Memory Abilities of ADHD Children Using the Stanford-Binet Intelligence Scales, Fifth Edition
Authors: Marusiak Christopher W. , Janzen Henry L.
Published: February 2007

The present study investigated the working memory abilities of children with attention deficit/hyperactivity disorder (ADHD) as measured by the Stanford-Binet Intelligence Scales, Fifth Edition (SBV). In a retrospective causal-comparative design, the archival data of 46 ADHD children were compared to 59 nondiagnosed children. The ADHD children scored significantly lower in measures of working memory compared to the control group. Within the ADHD group, working memory was the lowest factor score, significantly lower than three of the four other factors. Significant differences were also revealed within the working memory factor, with ADHD children displaying significantly lower nonverbal working memory scores than verbal working memory. No such differences were evident in the control group. The results are interpreted within Baddeley’s working memory model.
Pratiques et Perceptions des Psychologues Scolaires Face à l’Évaluation des Élèves en Difficulté d’Apprentissage au Québec
Authors: Béland Karina , Goupil Georgette
Published: February 2007

This article explores the assessment practices of Quebec school psychologists in the evaluation of elementary school students referred for suspected learning disabilities as well as their perceptions of these practices. The purpose of this study is to identify the ratio of learning disabled students within the school psychologist’s clientele, the time spent assessing these students, the learning disabilities definition used by psychologists, the most frequently used assessment tools, and the psychologist’s role in the diagnosis of learning disabilities. Seventy-six school psychologists participate in this research. The majority of participants estimates that learning-disabled students represent more than 50% of their clientele. Seventy-two percent of the time they devote to these students is spent doing assessments. Results show that all participants use the Wechsler Scales. However, their assessment practices vary greatly, as they use a variety of other tests. They deplore the lack of consensus over assessment and identification procedures.
Steady Thermoelastic Oscillations in a Linear Theory of Plane Elasticity with Microstructure
Authors: Shmoylova E. , Potapenko S. , Rothenburg L.
Published: February 2007

In the present paper we consider the problem of steady thermoelastic oscillations in a linear theory of plane elasticity with microstructure where disturbance is represented by a train of harmonic waves. The corresponding boundary value problems of Dirichlet and Neumann type are formulated and solutions are obtained in the form of integral potentials using the real boundary integral equation method. Appropriate Sommerfeld radiation conditions are prescribed in the case of the exterior domain and the uniqueness result is established.
Defective targeting of hemojuvelin to plasma membrane is a common pathogenetic mechanism in juvenile hemochromatosis
Authors: Silvestri Laura , Pagani Alessia , Fazi Claudia , Gerardi Gianmario , Levi Sonia , Arosio Paolo , Camaschella Clara
Published: February 2007

Hemojuvelin (HJV) positively modulates the iron regulator hepcidin, and its mutations are the major cause of juvenile hemochromatosis (JH), a recessive disease leading to iron overload. Defective HJV reduces hepcidin up-regulation both in humans and in Hjv-deficient mice. To investigate the JH pathogenesis and the functional properties of human HJV we studied the biosynthesis and maturation of 6 HJV pathogenic mutants in HeLa and HepG2 cells. We show that proteolytic processing is defective in mutants F170S, W191C, and G320V, but not in G99V and C119F. Moreover, we show that mutants G99V and C119F are targeted to the cell surface, while F170S, W191C, G320V, and R326X (lacking the glycosilphosphatidylinositol [GPI] anchor) are mainly retained in the endoplasmic reticulum, although all mutants are released as soluble forms (s-HJV) in a proportion that is modulated by iron supplementation. Membrane HJV (m-HJV) is mainly composed of the cleaved protein, and its level is increased by iron in wild-type (WT) mice but not in the mutants. Altogether, the data demonstrate that the loss of HJV membrane export is central to the pathogenesis of JH, and that HJV cleavage is essential for the export. The results support a dual function for s- and m-HJV in iron deficiency and overload, respectively.
Bone marrow transplantation for severe aplastic anemia: a randomized controlled study of conditioning regimens
Authors: Champlin Richard E. , Perez Waleska S. , Passweg Jakob R. , Klein John P. , Camitta Bruce M. , Gluckman Eliane , Bredeson Christopher N. , Eapen Mary , Horowitz Mary M.
Published: February 2007

The addition of antithymocyte globulin (ATG) to a regimen of high-dose cyclophosphamide has been advocated to enhance engraftment after allogeneic bone marrow transplantation (BMT) for severe aplastic anemia (SAA). In a prospective clinical trial, 134 patients were randomly assigned to receive cyclophosphamide alone or in combination with ATG. All patients received T-cell–replete bone marrow from an HLA-matched sibling. With a median follow-up of 6 years, the 5-year probabilities of survival were 74% for the cyclophosphamide alone group and 80% for the cyclophosphamide plus ATG group (P = .44). Graft failure and graft-versus-host disease (GVHD) rates were similar in both groups. With the survival rates achieved, this study is not adequately powered to detect significant differences between the 2 treatment groups. In conclusion, the results of allogeneic BMT for SAA have improved over time related to advances in supportive care. The addition of ATG to the preparative regimen did not significantly improve the outcome.
Computational RNA secondary structure design: empirical complexity and improved methods
Authors: Aguirre-Hernández Rosalía , Hoos Holger H , Condon Anne
Published: February 2007

Background

We investigate the empirical complexity of the RNA secondary structure design problem, that is, the scaling of the typical difficulty of the design task for various classes of RNA structures as the size of the target structure is increased. The purpose of this work is to understand better the factors that make RNA structures hard to design for existing, high-performance algorithms. Such understanding provides the basis for improving the performance of one of the best algorithms for this problem, RNA-SSD, and for characterising its limitations.

Results

To gain insights into the practical complexity of the problem, we present a scaling analysis on random and biologically motivated structures using an improved version of the RNA-SSD algorithm, and also the RNAinverse algorithm from the Vienna package. Since primary structure constraints are relevant for designing RNA structures, we also investigate the correlation between the number and the location of the primary structure constraints when designing structures and the performance of the RNA-SSD algorithm. The scaling analysis on random and biologically motivated structures supports the hypothesis that the running time of both algorithms scales polynomially with the size of the structure. We also found that the algorithms are in general faster when constraints are placed only on paired bases in the structure. Furthermore, we prove that, according to the standard thermodynamic model, for some structures that the RNA-SSD algorithm was unable to design, there exists no sequence whose minimum free energy structure is the target structure.

Conclusion

Our analysis helps to better understand the strengths and limitations of both the RNA-SSD and RNAinverse algorithms, and suggests ways in which the performance of these algorithms can be further improved.
Heritable clustering and pathway discovery in breast cancer integrating epigenetic and phenotypic data
Authors: Wang Zailong , Yan Pearlly , Potter Dustin , Eng Charis , Huang Tim H-M , Lin Shili
Published: February 2007

Background

In order to recapitulate tumor progression pathways using epigenetic data, we developed novel clustering and pathway reconstruction algorithms, collectively referred to as heritable clustering. This approach generates a progression model of altered DNA methylation from tumor tissues diagnosed at different developmental stages. The samples act as surrogates for natural progression in breast cancer and allow the algorithm to uncover distinct epigenotypes that describe the molecular events underlying this process. Furthermore, our likelihood-based clustering algorithm has great flexibility, allowing for incomplete epigenotype or clinical phenotype data and also permitting dependencies among variables.

Results

Using this heritable clustering approach, we analyzed methylation data obtained from 86 primary breast cancers to recapitulate pathways of breast tumor progression. Detailed annotation and interpretation are provided to the optimal pathway recapitulated. The result confirms the previous observation that aggressive tumors tend to exhibit higher levels of promoter hypermethylation.

Conclusion

Our results indicate that the proposed heritable clustering algorithms are a useful tool for stratifying both methylation and clinical variables of breast cancer. The application to the breast tumor data illustrates that this approach can select meaningful progression models which may aid the interpretation of pathways having biological and clinical significance. Furthermore, the framework allows for other types of biological data, such as microarray gene expression or array CGH data, to be integrated.
Localisation of increased prefrontal white matter in
pathological liars
Authors: Yang Yaling , Raine Adrian , Narr Katherine L. , Lencz Todd , LaCasse Lori , Colletti Patrick , Toga Arthur W
Published: February 2007

We examined white matter volumes in four prefrontal subregions using
structural magnetic resonance imaging in 10 pathological liars, 14
antisocial controls, and 20 normal controls. Liars showed a relatively
widespread increase in white matter (23-36%) in orbitofrontal, middle and
inferior, but not superior, frontal gyri compared with antisocial and normal
controls. This white matter increase may predispose some individuals to
pathological lying.
Researching recovery from psychosis: a user-led project
Authors: Pitt Liz , Kilbride Martina , Nothard Sarah , Welford Mary , Morrison Anthony P.
Published: February 2007

Aims and Method

Involvement of service users in the research process and examination of recovery from psychosis are two topics that have generated recent interest within the research community. This user-led study examines the subjective experience of recovery in people with experience of psychosis. Seven interviews were analysed using interpretative phenomenological analysis and several themes emerged from the data.

Results

Recovery from psychosis was found to be a complex and idiosyncratic process, which often involved rebuilding life, rebuilding self and hope for a better future (each of these themes consisted of sub-themes).

Clinical Implications

The importance of continuity of care, the need for greater choice in approaches aimed at alleviating distress, access to stories of recovery and encouragement, and the importance of more individualised recovery care plans are among factors highlighted.
Case-based online learning for medical undergraduates
Authors: Hare Elizabeth H. , Evans Phillip , McIntosh Claire E. , Thomson Lindsay D. G.
Published: February 2007

Online learning is a tool for teaching and assessing students but to date it has been under-utilised in psychiatry. This article outlines the evidence base for such approaches and gives an illustrative account of developing modules for medical undergraduates on the topic of alcohol use and misuse. This may act as a guideline for the development of other psychiatric teaching modules.
Disparities in the Emergency Department Evaluation of Chest Pain Patients
Authors: Pezzin Liliana E. , Keyl Penelope M. , Green Gary B.
Published: February 2007

Background

The existence of race and gender differences in the provision of cardiovascular health care has been increasingly recognized. However, few studies have examined whether these differences exist in the emergency department (ED) setting.

Objectives

To evaluate race, gender, and insurance differences in the receipt of early, noninvasive diagnostic tests among persons presenting to an ED with a complaint of chest pain.

Methods

Data were drawn from the U.S. National Hospital Ambulatory Health Care Survey of EDs. Visits made during 1995–2000 by persons aged 30 years or older with chest pain as a reason for the visit were included. Factors affecting the likelihood of ordering electrocardiography, cardiac monitoring, oxygen saturation measurement using pulse oximetry, and chest radiography were analyzed using multivariate probit analysis.

Results

A total of 7,068 persons aged 30 years or older presented to an ED with a primary complaint of chest pain during the six‐year period, corresponding to more than 32 million such visits nationally. The adjusted probability of ordering a test was highest for non–African American patients for all tests considered. African American men had the lowest probabilities (74.3% and 62% for electrocardiography and chest radiography, respectively), compared with 81.1% and 70.3%, respectively, among non–African American men. Only 37.5% of African American women received cardiac monitoring, compared with 54.5% of non–African American men. Similarly, African American women were significantly less likely than non–African American men to have their oxygen saturation measured. Patients who were uninsured or self‐pay, as well as patients with “other” insurance, also had a lower probability than insured persons of having these tests ordered.

Conclusions

This study documents race, gender, and insurance differences in the provision of electrocardiography and chest radiography testing as well as cardiac rhythm and oxygen saturation monitoring in patients presenting with chest pain. These observed differences should catalyze further study into the underlying causes of disparities in cardiac care at an earlier point of patient contact with the health care system.
Procedural Sedation and Analgesia Research: State of the Art
Authors: Miner James R. , Krauss Baruch
Published: February 2007

The authors review the current state of procedural sedation and analgesia research and clinical practice in adults and children, discuss the limitations in research methodology, and propose future areas of investigation.
DrosophilaVaricose, a member of a new subgroup of basolateral MAGUKs, is required for septate junctions and tracheal morphogenesis
Authors: Wu Victoria M. , Yu Marcus H. , Paik Raehum , Banerjee Swati , Liang Zhiguo , Paul Sarah M. , Bhat Manzoor A. , Beitel Greg J.
Published: February 2007

Epithelial tubes are the functional units of many organs, but little is known about how tube sizes are established. Using the Drosophilatracheal system as a model, we previously showed that mutations in varicose (vari) cause tubes to become elongated without increasing cell number. Here we show vari is required for accumulation of the tracheal size-control proteins Vermiform and Serpentine in the tracheal lumen. We also show that vari is an essential septate junction (SJ) gene encoding a membrane associated guanylate kinase (MAGUK). In vivo analyses of domains important for MAGUK scaffolding functions demonstrate that while the Vari HOOK domain is essential, the L27 domain is dispensable. Phylogenetic analyses reveal that Vari helps define a new MAGUK subgroup that includes mammalian PALS2. Importantly, both Vari and PALS2 are basolateral,and the interaction of Vari with the cell-adhesion protein Neurexin IV parallels the interaction of PALS2 and another cell-adhesion protein, Necl-2. Vari therefore bolsters the similarity between Drosophila and vertebrate epithelial basolateral regions, which had previously been limited to the common basolateral localization of Scrib, Dlg and Lgl, proteins required for epithelial polarization at the beginning of embryogenesis. However, by contrast to Scrib, Dlg and Lgl, Vari is not required for cell polarity but rather is part of a cell-adhesion complex. Thus, Vari fundamentally extends the similarity of Drosophila and vertebrate basolateral regions from sharing only polarity complexes to sharing both polarity and cell-adhesion complexes.
Flexible information sampling in vibrational assessment of predation risk by red-eyed treefrog embryos
Authors: Warkentin Karen M. , Caldwell Michael S. , Siok Timothy D. , D'Amato Alison T. , McDaniel J. Gregory
Published: February 2007

Prey assessing risk may miss cues and fail to defend themselves, or respond unnecessarily to false alarms. Error rates can be ameliorated with more information, but sampling predator cues entails risk. Red-eyed treefrogs have arboreal eggs and aquatic tadpoles. The embryos use vibrations in snake attacks to cue behaviorally mediated premature hatching, and escape, but vibrations from benign sources rarely induce hatching. Missed cues and false alarms are costly; embryos that fail to hatch are eaten and hatching prematurely increases predation by aquatic predators. Embryos use vibration duration and spacing to inform their hatching decision. This information accrues with cycles of vibration, while risk accrues over time as snakes feed. We used vibration playback experiments to test if embryos adjust sampling of information based on its cost, and measured latency to initiate hatching in videotaped snake attacks. Embryos did not initiate hatching immediately in attacks or playbacks, and the delay varied with the rate at which information accrued. Embryos started hatching sooner in response to stimuli with shorter cycles but sampled fewer cycles (less information) of longer-cycle stimuli before hatching. This flexible sampling is consistent with embryos balancing a trade-off between the value and cost of information.
Plasticity and superplasticity in the acclimation potential of the Antarctic mite Halozetes belgicae (Michael)
Authors: Hawes T. C. , Bale J. S. , Worland M. R. , Convey P.
Published: February 2007

The plasticity of an organism's phenotype may vary spatially and temporally, and across levels of physiological organisation. Given the adaptive value of plasticity in heterogeneous environments, it might be expected that it will be expressed most in a phenotype's most significant adaptive suites; at high latitudes, one of these is low temperature adaptation. This study examines the phenotypic plasticity of cold acclimation in the Antarctic mite, Halozetes belgicae (Michael). Both plastic and`superplastic' (extreme plasticity) acclimation responses were found. Plastic responses were evident in responses to laboratory acclimation and field acclimatisation. `Superplasticity' was found in its ability to rapidly cold harden (RCH) at 0, –5 and –10°C. For example, after just 2 h of acclimation at 0°C, mites acclimated at 10°C shifted their supercooling points (SCPs) by approx. 15°C. In terms of the combined speed of induction and lowering of lethal temperature, this is the most potent RCH response yet reported for a terrestrial arthropod. RCH was also expressed in thermal activity thresholds. Mechanisms responsible for significant differences in recovery from chill torpor are unknown; however, analysis of gut nucleator abundance suggest that the dynamic management of supercooling potential is largely achieved behaviourally, via evacuation. Comparisons with the literature reveal that plasticity in this species varies latitudinally, as well as temporally. The high degree of plasticity identified here is coincident with H. belgicae's occupation of the most exposed spatial niche available to Antarctic terrestrial arthropods.
Dynamics of the body centre of mass during actual acceleration across transition speed
Authors: Segers Veerle , Aerts Peter , Lenoir Matthieu , De Clerq Dirk
Published: February 2007

Judged by whole body dynamics, walking and running in humans clearly differ. When walking, potential and kinetic energy fluctuate out-of-phase and energy is partially recovered in a pendulum-like fashion. In contrast, running involves in-phase fluctuations of the mechanical energy components of the body centre of mass, allowing elastic energy recovery. We show that, when constantly accelerating across the transition speed, humans make the switch from walking to running abruptly in one single step. In this step, active mechanical energy input triples the normal step-by-step energy increment needed to power the imposed constant acceleration. This extra energy is needed to launch the body into the flight phase of the first running step and to bring the trunk into its more inclined orientation during running. Locomotor cycles immediately proceed with the typical in-phase fluctuations of kinetic and potential energy. As a result, the pendular energy transfer drops in one step from 43% to 5%. Kinematically, the transition step is achieved by landing with the knee and hip significantly more flexed compared to the previous walking steps. Flexion in these joints continues during the first half of stance, thus bringing the centre of mass to its deepest position halfway through stance phase to allow for the necessary extension to initiate the running gait. From this point of view, the altered landing conditions seem to constitute the actual transition.
Synchronizing multiphasic circadian rhythms of rhodopsin promoter expression in rod photoreceptor cells
Authors: Yu Chuan-Jiang , Gao Yan , Li Ping , Li Lei
Published: February 2007

Endogenous circadian clocks regulate day–night rhythms of animal behavior and physiology. In zebrafish, the circadian clocks are located in the pineal gland and the retina. In the retina, each photoreceptor is considered a circadian oscillator. A critical question is whether the individual circadian oscillators are synchronized. If so, the mechanism that underlies the synchronization needs to be elucidated. We generated a transgenic zebrafish line that expresses short half-life GFP under the transcriptional control of the rhodopsin promoter. Time-lapse imaging of rhodopsin promoter-driven GFP expression revealed that during 24 h in constant darkness, rhodopsin promoter expression in rod photoreceptor cells fluctuated rhythmically. However, the pattern of fluctuation differed between individual cells. In some cells, peak expression was seen in the subjective early morning, whereas in other cells,peak expression was seen in the afternoon or at night. Light transiently decreased rhodopsin expression, thereby synchronizing the multiphasic circadian oscillation. The application of dopamine or dopamine D2receptor agonist also synchronized the circadian rhythms of rhodopsin promoter expression. When the D2 receptors were pharmacologically blocked,light exposure produced no effect. This suggests that the synchronization of the circadian rhythms of rhodopsin promoter expression by light is mediated by dopamine D2 receptors. The mechanism that underlies the synchronization probably involves dopamine-mediated Ca2+ signaling pathways. Light, as well as dopamine, lowered Ca2+ influx into the rod cells, thereby resetting rhodopsin promoter expression to the initial phase.
Cooling rates and body temperature regulation of hibernating echidnas(Tachyglossus aculeatus)
Authors: Nicol Stewart C. , Andersen Niels A.
Published: February 2007

Echidnas (Tachyglossus aculeatus) are amongst the largest deep hibernators, but it is difficult to get them to hibernate normally under laboratory conditions. We measured body temperature (Tb)in 14 free-ranging echidnas using implanted data-loggers. Cooling during entry into hibernation bouts followed a Newtonian cooling curve, and conductances calculated from cooling curves were identical to those observed in cold exposed euthermic echidnas. Comparison with a reference soil temperature demonstrated that echidnas showed behavioural thermoregulation during hibernation; early in the hibernation season echidnas preferred to hibernate in cool areas, while during the coldest months they moved to warmer hibernacula, giving a preferred Tb in the range 8–10°C. Thermal buffering against excessive variation in Tb may be as important as maintaining a low Tb.
Modelling the acceleration and braking characteristics of a fuel-cell electric sports vehicle equipped with an ultracapacitor
Authors: Marco J , Vaughan N D , Spowers H , McCulloch M
Published: February 2007

The traditional method of assessing the performance of a hybrid electric power-train is to construct a backward-facing model of the vehicle and then to exercise that model over a number of different legislative and ‘real-world’ drive cycles. Because of the low rates of acceleration and braking associated with such drive cycles, the effect of tyre dynamics on vehicle performance and powertrain efficiency, including that of regenerative braking, have been generally ignored in previous studies. Contained within this paper is the design of a detailed mathematical, physics-based model of a lightweight fuel-cell hybrid sports vehicle. The model is appropriate for studying the dynamic performance of the powertrain during periods of high acceleration and regenerative braking that are commensurate with the use of the vehicle as a sports car. The model characterizes both the electrical subsystems within the powertrain and the mechanical components including the longitudinal dynamics of the tyres. Simulation results show that, during rapid acceleration and braking, the effect of tyre losses on the performance and energy efficiency of the powertrain cannot be neglected. In addition, control objectives for the vehicle are also identified that aim to maximize the potential benefits associated with the integration of fuel-cell and ultracapacitor technology.
Adoption of state feedback to control dynamics of a vehicle with a steer-by-wire system
Authors: Chang Shun Chang
Published: February 2007

This investigation confirms the chaotic motion of a vehicle with a steer-by-wire system, and then elucidates a system for controlling the chaos. A bifurcation diagram reveals complex non-linear behaviours over a range of parameter values. Next, the largest Lyapunov exponent is estimated to identify periodic and chaotic motions. Finally, the state feedback control approach for controlling a chaotic cornering vehicle is presented. The control of chaos prevents the driver from cornering the vehicle dangerously, so the controlled vehicle exhibits stable cornering behaviour. Some simulation results are presented to reveal the feasibility of the presented approach.
Impulse loading resulting from shallow buried explosives in water-saturated sand
Authors: Grujicic M , Pandurangan B , Huang Y , Cheeseman B A , Roy W N , Skaggs R R
Published: February 2007

A transient non-linear dynamics analysis of the detonation of a landmine buried to different depths in water-saturated sand is carried out in order to determine the resulting impulse loading. The results obtained are compared with their experimental counterparts obtained using the vertical impulse measurement fixture (VIMF), a structural mechanical device that enables direct experimental determination of the blast-loading impulse. The mechanical response of the structural steel used in the construction of the VIMF and the hydrodynamic response of the TNT high-energy high-pressure detonation products generated during detonation of a mine and of the air surrounding the VIMF are represented using the standard materials models available in the literature. The mechanical response of the sand surrounding the mine, on the other hand, is represented using the present authors' recent modified compaction model [1], which incorporates the effects of degree of saturation and the rate of deformation, two important effects, that are generally neglected in standard constitutive models for sand. The results obtained indicate that the use of the modified compaction model yields a substantially better agreement with the experimentally determined impulse loads over the use the original compaction model. Furthermore, the results suggest that, in the case of fully saturated sand, the blast loading is of a bubble type rather than of a shock type, i.e. it resembles under-water explosion.
Estimating the Effects of Global Patent Protection in Pharmaceuticals: A Case Study of Quinolones in India
Authors: Chaudhuri Shubham , Goldberg Pinelopi K , Jia Panle
Published: February 2007

Under the Agreement on Trade-Related Intellectual Property Rights, the World Trade Organization members are required to enforce product patents for pharmaceuticals. In this paper we empirically investigate the welfare effects of this requirement on developing countries using data for the fluoroquinolones subsegment of the systemic anti-bacterials segment of the Indian pharmaceuticals market. Our results suggest that concerns about the potential adverse welfare effects of TRIPS may have some basis. We estimate that the withdrawal of all domestic products in this subsegment is associated with substantial welfare losses to the Indian economy, even in the presence of price regulation. The overwhelming portion of this welfare loss derives from the loss of consumer welfare.
Incentives and Prosocial Behavior
Authors: Bénabou Roland , Tirole Jean
Published: February 2007

We develop a theory of prosocial behavior that combines heterogeneity in individual altruism and greed with concerns for social reputation or self-respect. Rewards or punishments (whether material or image-related) create doubt about the true motive for which good deeds are performed, and this “overjustification effect” can induce a partial or even net crowding out of prosocial behavior by extrinsic incentives. We also identify the settings that are conducive to multiple social norms and, more generally, those that make individual actions complements or substitutes, which we show depends on whether stigma or honor is (endogenously) the dominant reputational concern. Finally, we analyze the socially optimal level of incentives and how monopolistic or competitive sponsors depart from it. Sponsor competition is shown to potentially reduce social welfare.
Self-Fulfilling Currency Crises: The Role of Interest Rates
Authors: Hellwig Christian , Mukherji Arijit , Tsyvinski Aleh
Published: February 2007

We develop a model of currency crises, in which traders are heterogeneously informed, and interest rates are endogenously determined in a noisy rational expectations equilibrium. In our model, multiple equilibria result from distinct roles an interest rate plays in determining domestic asset market allocations and the devaluation outcome. Except for special cases, this finding is not affected by the introduction of noisy private signals. We conclude that the global games results on equilibrium uniqueness do not apply to market-based models of currency crises.
Child Labor and the Labor Supply of Other Household Members: Evidence from 1920 America
Authors: Manacorda Marco
Published: February 2007

This paper exploits the variation in the legal minimum working age across states in 1920 America in order to identify households' labor supply responses to exogenous changes in children's labor force participation. Using micro data on urban households from the U.S. Census, I find evidence that as a child moves to the labor market his siblings are less likely to work and more likely to attend school. I find no significant effect on parents' labor supply.
How Special Is the Special Relationship? Using the Impact of U.S. R&D Spillovers on U.K. Firms as a Test of Technology Sourcing
Authors: Griffith Rachel , Harrison Rupert , Van Reenen John
Published: February 2007

We examine the “technology sourcing” hypothesis that foreign research labs located in the U.S. tap into U.S. R&D spillovers and improve home country productivity. We show that U.K. firms that established a high proportion of inventors based in the U.S. by 1990 benefited disproportionately from the growth of U.S. R&D stock over the next ten years. We estimate that U.S. R&D during the 1990s was associated with 5 percent higher Total Factor Productivity for U.K. manufacturing firms in 2000 (about $13 billion), with the majority of benefits accruing to firms with an innovative presence in the U.S.
Goodbye Washington Consensus, Hello Washington Confusion? A Review of the World Bank's Economic Growth in the 1990s: Learning from a Decade of Reform
Authors: Rodrik Dani
Published: February 2007

Proponents and critics alike agree that the policies spawned by the Washington Consensus have not produced the desired results. The debate now is not over whether the Washington Consensus is dead or alive, but over what will replace it. An important marker in this intellectual terrain is the World Bank's Economic Growth in the 1990s: Learning from a Decade of Reform (2005). With its emphasis on humility, policy diversity, selective and modest reforms, and experimentation, this is a rather extraordinary document demonstrating the extent to which the thinking of the development policy community has been transformed over the years. But there are other competing perspectives as well. One (trumpeted elsewhere in Washington) puts faith on extensive institutional reform, and another (exemplified by the U.N. Millennium Report) puts faith on foreign aid. Sorting intelligently among these diverse perspectives requires an explicitly diagnostic approach that recognizes that the binding constraints on growth differ from setting to setting.
Gender power imbalance and differential psychosocial correlates of intended condom use among male and female adolescents from Venda, South Africa
Authors: Boer Henk , Tshilidzi Mashamba M.
Published: February 2007

Objectives.In South Africa, a gender power imbalance exists which may prevent women from negotiating safe sexual encounters. In this study we tested which constructs from Protection Motivation Theory (PMT) and the Theory of Planned Behavior (TPB) under these circumstances were most related to condom use intention. We hypothesized that in a situation of gender power imbalance self‐efficacy would be a more salient correlate of intended condom use for females, while for males attitude to condoms and subjective norm would be more important.

Design.This study employed a cross‐sectional questionnaire design.

Method.Male participants (N= 94) and female participants (N= 101) from Venda, South Africa completed standard, multi‐item, reliable measures of TPB constructs (condom‐related attitude, subjective norm, perceived behavioural control, intention) and PMT constructs (vulnerability, severity, fear, response‐efficacy, self‐efficacy) and reported their past condom use behaviour.

Results.Regression analysis indicated that among males attitude to condoms and subjective norm were significantly related to intended condom use. Among females attitude and self‐efficacy were significantly related to intended condom use.

Conclusion.The findings indicate that in a situation of gender power imbalance psychosocial correlates of intended condom use differ for males and females. Gender‐specific analysis of determinants of condom use may be more appropriate in a situation of gender power imbalance.
Recent results toward the stereoselective synthesis of biologically active natural products
Authors: Dias Luiz C. , de Oliveira Luciana G. , Meira Paulo R. R.
Published: February 2007

This paper describes the convergent and stereocontrolled asymmetric total synthesis of (+)-crocacins C and D, potent inhibitors of animal cell cultures and several yeasts and fungi, and (-)-callystatin A, a potent antitumor polyketide.