bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanotransduction at Cell-Matrix and Cell-Cell Contacts
Authors: Chen Christopher S. , Tan John , Tien Joe
Published: July 2004

▪ Abstract  Mechanical forces play an important role in the organization, growth, maturation, and function of living tissues. At the cellular level, many of the biological responses to external forces originate at two types of specialized microscale structures: focal adhesions that link cells to their surrounding extracellular matrix and adherens junctions that link adjacent cells. Transmission of forces from outside the cell through cell-matrix and cell-cell contacts appears to control the maturation or disassembly of these adhesions and initiates intracellular signaling cascades that ultimately alter many cellular behaviors. In response to externally applied forces, cells actively rearrange the organization and contractile activity of the cytoskeleton and redistribute their intracellular forces. Recent studies suggest that the localized concentration of these cytoskeletal tensions at adhesions is also a major mediator of mechanical signaling. This review summarizes the role of mechanical forces in the formation, stabilization, and dissociation of focal adhesions and adherens junctions and outlines how integration of signals from these adhesions over the entire cell body affects how a cell responds to its mechanical environment. This review also describes advanced optical, lithographic, and computational techniques for the study of mechanotransduction.
Fractal Analysis of the Vascular Tree in the Human Retina
Authors: Masters Barry R.
Published: July 2004

▪ Abstract  The retinal circulation of the normal human retinal vasculature is statistically self-similar and fractal. Studies from several groups present strong evidence that the fractal dimension of the blood vessels in the normal human retina is approximately 1.7. This is the same fractal dimension that is found for a diffusion-limited growth process, and it may have implications for the embryological development of the retinal vascular system. The methods of determining the fractal dimension for branching trees are reviewed together with proposed models for the optimal formation (Murray Principle) of the branching vascular tree in the human retina and the branching pattern of the human bronchial tree. The limitations of fractal analysis of branching biological structures are evaluated. Understanding the design principles of branching vascular systems and the human bronchial tree may find applications in tissue and organ engineering, i.e., bioartificial organs for both liver and kidney.
Fluid Mechanics of Heart Valves
Authors: Yoganathan Ajit P. , He Zhaoming , Casey Jones S.
Published: July 2004

▪ Abstract  Valvular heart disease is a life-threatening disease that afflicts millions of people worldwide and leads to approximately 250,000 valve repairs and/or replacements each year. Malfunction of a native valve impairs its efficient fluid mechanic/hemodynamic performance. Artificial heart valves have been used since 1960 to replace diseased native valves and have saved millions of lives. Unfortunately, despite four decades of use, these devices are less than ideal and lead to many complications. Many of these complications/problems are directly related to the fluid mechanics associated with the various mechanical and bioprosthetic valve designs. This review focuses on the state-of-the-art experimental and computational fluid mechanics of native and prosthetic heart valves in current clinical use. The fluid dynamic performance characteristics of caged-ball, tilting-disc, bileaflet mechanical valves and porcine and pericardial stented and nonstented bioprostheic valves are reviewed. Other issues related to heart valve performance, such as biomaterials, solid mechanics, tissue mechanics, and durability, are not addressed in this review.
Mechanical Bioeffects of Ultrasound
Authors: Dalecki Diane
Published: July 2004

▪ Abstract  Ultrasound is used widely in medicine as both a diagnostic and therapeutic tool. Through both thermal and nonthermal mechanisms, ultrasound can produce a variety of biological effects in tissues in vitro and in vivo. This chapter provides an overview of the fundamentals of key nonthermal mechanisms for the interaction of ultrasound with biological tissues. Several categories of mechanical bioeffects of ultrasound are then reviewed to provide insight on the range of ultrasound bioeffects in vivo, the relevance of these effects to diagnostic imaging, and the potential application of mechanical bioeffects to the design of new therapeutic applications of ultrasound in medicine.
Molecular Machines
Authors: Mavroidis C. , Dubey A. , Yarmush M.L.
Published: July 2004

▪ Abstract  Molecular machines are tiny energy conversion devices on the molecular-size scale. Whether naturally occurring or synthetic, these machines are generally more efficient than their macroscale counterparts. They have their own mechanochemistry, dynamics, workspace, and usability and are composed of nature's building blocks: namely proteins, DNA, and other compounds, built atom by atom. With modern scientific capabilities it has become possible to create synthetic molecular devices and interface them with each other. Countless such machines exist in nature, and it is possible to build artificial ones by mimicking nature. Here we review some of the known molecular machines, their structures, features, and characteristics. We also look at certain devices in their early development stages, as well as their future applications and challenges.
Optical Projection Tomography
Authors: Sharpe James
Published: July 2004

▪ Abstract  Optical projection tomography is a new approach for three-dimensional (3-D) imaging of small biological specimens. It fills an imaging gap between MRI and confocal microscopy, being most suited to specimens that are from 1 to 10 mm across. The tomographic principles of optical projection tomography (OPT) are explained, its most important applications in biomedical research explored, and comparisons drawn of its pros and cons compared to a number of alternative imaging technologies.
Functional Efficacy of Tendon Repair Processes
Authors: Butler David L. , Juncosa Natalia , Dressler Matthew R.
Published: July 2004

▪ Abstract  Despite various attempts to repair and replace injured tendon, an understanding of the repair processes and a systematic approach to achieving functional efficacy remain elusive. In this review the epidemiology of tendon injury and repair is first examined. Using a traditional paradigm for repair assessment, the biology and biomechanics of normal tendon, natural healing, and repair are then explored. New treatment strategies such as functional tissue engineering are discussed, including a functional approach to treatment that involves the development of in vivo functional design parameters to judge the acceptability of a repair outcome. The paper concludes with future directions.
Tissue Growth and Remodeling
Authors: Cowin Stephen C.
Published: July 2004

▪ Abstract  The growth and remodeling of a tissue depends on certain features in the history of its mechanical environment as well as its genetic makeup. The mechanical environment influences the tissue's developing morphology, the process of simply increasing the size of existing morphological structures, and the formation of the proteins of which the tissue is constructed. The relationships between genetic information, various epigenetic mechanisms and tissue development are discussed. The developmental growth and remodeling of most structural tissues are enhanced by the use of those tissues and retarded by their disuse. The mechanical or mathematical modeling of tissue growth and development using cellular automata models and continuum mechanical models is reviewed.
Cation selectivity and inhibition of malignant glioma Na+ channels by Psalmotoxin 1
Authors: Bubien James K. , Ji Hong-Long , Gillespie G. Yancey , Fuller Catherine M. , Markert James M. , Mapstone Timothy B. , Benos Dale J.
Published: July 2004

Psalmotoxin 1 (a component of the venom of a West Indies tarantula) is a 40-amino acid peptide that inhibits cation currents mediated by acid-sensing ion channels (ASIC). In this study we performed electrophysiological experiments to test the hypothesis that Psalmotoxin 1 (PcTX1) inhibits Na+ currents in high-grade human astrocytoma cells (glioblastoma multiforme, or GBM). In whole cell patch-clamped cultured GBM cells, the peptide toxin quickly and reversibly inhibited both inward and outward current with an IC50 of 36 ± 2 pM. The same inhibition was observed in freshly resected GBM cells. However, when the same experiment was performed on normal human astrocytes, the toxin failed to inhibit the whole cell current. We also determined a cationic selectivity sequence for inward currents in three cultured GBM cell lines (SK-MG-1, U87-MG, and U251-MG). The selectivity sequence yielded a unique biophysical fingerprint with inward K+ conductance approximately fourfold greater than that of Na+, Li+, and Ca2+. These observations suggest that PcTX1 may prove useful in determining whether GBM cells express a specific ASIC-containing ion channel type that can serve as a target for both diagnostic and therapeutic treatments of aggressive malignant gliomas.
The Na+-K+-ATPase α2-subunit isoform modulates contractility in the perinatal mouse diaphragm
Authors: Radzyukevich Tatiana L. , Moseley Amy E. , Shelly Daniel A. , Redden Gregory A. , Behbehani Michael M. , Lingrel Jerry B. , Paul Richard J. , Heiny Judith A.
Published: July 2004

This study uses genetically altered mice to examine the contribution of the Na+-K+-ATPase α2 catalytic subunit to resting potential, excitability, and contractility of the perinatal diaphragm. The α2 protein is reduced by 38% in α2-heterozygous and absent in α2-knockout mice, and α1-isoform is upregulated 1.9-fold in α2-knockout. Resting potentials are depolarized by 0.8–4.0 mV in heterozygous and knockout mice. Action potential threshold, overshoot, and duration are normal. Spontaneous firing, a developmental function, is impaired in knockout diaphragm, but this does not compromise its ability to fire evoked action potential trains, the dominant mode of activation near birth. Maximum tetanic force, rate of activation, force-frequency and force-voltage relationships, and onset and magnitude of fatigue are not changed. The major phenotypic consequence of reduced α2 content is that relaxation from contraction is 1.7-fold faster. This finding reveals a distinct cellular role of the α2-isoform at a step after membrane excitation, which cannot be restored simply by increasing α1 content. Na+/Ca2+ exchanger expression decreases in parallel with α2-isoform, suggesting that Ca2+ extrusion is affected by the altered α2 genotype. There are no major compensatory changes in expression of sarcoplasmic reticulum Ca2+-ATPase, phospholamban, or plasma membrane Ca2+-ATPase. These results demonstrate that the Na+-K+-ATPase α1-isoform alone is able to maintain equilibrium K+ and Na+ gradients and to substitute for α2-isoform in most cellular functions related to excitability and force. They further indicate that the α2-isoform contributes significantly less at rest than expected from its proportional content but can modulate contractility during muscle contraction.
Voluntary running induces fiber type-specific angiogenesis in mouse skeletal muscle
Authors: Waters Richard E. , Rotevatn Svein , Li Ping , Annex Brian H. , Yan Zhen
Published: July 2004

Adult skeletal muscle undergoes adaptation in response to endurance exercise, including fast-to-slow fiber type transformation and enhanced angiogenesis. The purpose of this study was to determine the temporal and spatial changes in fiber type composition and capillary density in a mouse model of endurance training. Long-term voluntary running (4 wk) in C57BL/6 mice resulted in an approximately twofold increase in capillary density and capillary-to-fiber ratio in plantaris muscle as measured by indirect immunofluorescence with an antibody against the endothelial cell marker CD31 (466 ± 16 capillaries/mm2 and 0.95 ± 0.04 capillaries/fiber in sedentary control mice vs. 909 ± 55 capillaries/mm2 and 1.70 ± 0.04 capillaries/fiber in trained mice, respectively; P < 0.001). A significant increase in capillary-to-fiber ratio was present at day 7 with increased concentration of vascular endothelial growth factor (VEGF) in the muscle, before a significant increase in percentage of type IIa myofibers, suggesting that exercise-induced angiogenesis occurs first, followed by fiber type transformation. Further analysis with simultaneous staining of endothelial cells and isoforms of myosin heavy chains (MHCs) showed that the increase in capillary contact manifested transiently in type IIb + IId/x fibers at the time ( day 7) of significant increase in total capillary density. These findings suggest that endurance training induces angiogenesis in a subpopulation of type IIb + IId/x fibers before switching to type IIa fibers.
Adipocyte differentiation induces dynamic changes in NF-κB expression and activity
Authors: Berg Anders H. , Lin Ying , Lisanti Michael P. , Scherer Philipp E.
Published: July 2004

The adipocyte exerts an important role in energy homeostasis, both as depot for energy-rich triglycerides and as a source for metabolic hormones. Adipocytes also contribute to inflammation and the innate immune response. Although it can be physiologically beneficial to combine these two functions in a single cell type under some circumstances, the proinflammatory signals emanating from adipocytes in the obese state can have local and systemic effects that promote atherosclerosis and insulin resistance. The transcriptional machinery in the adipocyte that mediates these pro-inflammatory responses has remained poorly characterized to date. In particular, no information is currently available on the NF-κB family of transcription factors. Here, we show that adipogenesis is associated with changes in amount and subunit composition of the NF-κB complexes. NF-κB subunits p65 (RelA), p68 (RelB), and IκB are upregulated during fat cell differentiation. Correspondingly, basal NF-κB nuclear gel shift and luciferase reporter assays are induced in parallel during differentiation. Surprisingly, endotoxin sensitivity of the classical NF-κB pathway is substantially delayed and attenuated despite increased overall inflammatory response in the mature adipocyte, as judged by induction of IL-6 and TNF-α. As a reflection of the constitutively elevated NF-κB activity in the mature adipocyte, adipocytes (but not preadipocytes) exert a strong inflammatory stimulus on macrophages in vitro, suggesting a cross talk between adipocytes and interstitial macrophages in adipose tissue in vivo. These effects are mediated by a secretory product of adipocytes that is unlikely to be IL-6 or TNF-α.
Impaired muscle metaboreflex-induced increases in ventricular function in heart failure
Authors: O'Leary Donal S. , Sala-Mercado Javier A. , Augustyniak Robert A. , Hammond Robert L. , Rossi Noreen F. , Ansorge Eric J.
Published: July 2004

We investigated to what extent heart failure alters the ability of the muscle metaboreflex to improve ventricular function. Dogs were chronically instrumented to monitor mean arterial pressure (MAP), cardiac output (CO), heart rate (HR), stroke volume (SV), and central venous pressure (CVP) at rest and during mild treadmill exercise (3.2 km/h) before and during reductions in hindlimb blood flow imposed to activate the muscle metaboreflex. These control experiments were repeated at constant heart rate (ventricular pacing 225 beats/min) and at constant heart rate coupled with a β-adrenergic blockade (atenolol, 2 mg/kg iv) in normal animals and in the same animals after the induction of heart failure (HF, induced via rapid ventricular pacing). In control experiments in normal animals, metaboreflex activation caused tachycardia with no change in SV, resulting in large increases in CO and MAP. At constant HR, large increases in CO still occurred via significant increases in SV. Inasmuch as CVP did not change in this setting and that β-adrenergic blockade abolished the reflex increase in SV at constant HR, this increase in SV likely reflects increased ventricular contractility. In contrast, after the induction of HF, much smaller increases in CO occurred with metaboreflex activation because, although increases in HR still occurred, SV decreased thereby limiting any increase in CO. At constant HR, no increase in CO occurred with metaboreflex activation even though CVP increased significantly. After β-adrenergic blockade, CO and SV decreased with metaboreflex activation. We conclude that in HF, the ability of the muscle metaboreflex to increase ventricular function via both increases in contractility as well as increases in filling pressure are markedly impaired.
Urea may regulate urea transporter protein abundance during osmotic diuresis
Authors: Kim Dongun , Klein Janet D. , Racine Sandy , Murrell Brian P. , Sands Jeff M.
Published: July 2004

Rats with diabetes mellitus have an increase in UT-A1 urea transporter protein abundance and absolute urea excretion, but the relative amount (percentage) of urea in total urinary solute is actually decreased due to the marked glucosuria. Urea-specific signaling pathways have been identified in mIMCD3 cells and renal medulla, suggesting the possibility that changes in the percentage or concentration of urea could be a factor that regulates UT-A1 abundance. In this study, we tested the hypothesis that an increase in a urinary solute other than urea would increase UT-A1 abundance, similar to diabetes mellitus, whereas an increase in urine urea would not. In both inner medullary base and tip, UT-A1 protein abundance increased during NaCl- or glucose-induced osmotic diuresis but not during urea-induced osmotic diuresis. Next, rats undergoing NaCl or glucose diuresis were given supplemental urea to increase the percentage of urine urea to control values. UT-A1 abundance did not increase in these urea-supplemented rats compared with control rats. Additionally, both UT-A2 and UT-B protein abundances in the outer medulla increased during urea-induced osmotic diuresis but not in NaCl or glucose diuresis. We conclude that during osmotic diuresis, UT-A1 abundance increases when the percentage of urea in total urinary solute is low and UT-A2 and UT-B abundances increase when the urea concentration in the medullary interstitium is high. These findings suggest that a reduction in urine or interstitial urea results in an increase in UT-A1 protein abundance in an attempt to restore inner medullary interstitial urea and preserve urine-concentrating ability.
Contribution of Muscle Afferents to Prolonged Flexion Withdrawal Reflexes in Human Spinal Cord Injury
Authors: Hornby T. G. , Tysseling-Mattiace V. M. , Benz E. N. , Schmit B. D.
Published: July 2004

The contribution of force-sensitive muscular afferents to prolonged flexion withdrawal reflexes, or flexor spasms, after human spinal cord injury (SCI) was investigated. In three separate experimental conditions, flexion reflexes were triggered in subjects with SCI using trains of electrocutaneous stimuli delivered at the foot and lower leg and compared with reflexes elicited via intramuscular (IM) electrical stimuli. In the first experiment, flexion reflexes were elicited using IM stimuli to the tibialis anterior (TA) in the majority of subjects tested. The ratio of peak isometric ankle to hip torques during IM-triggered reflexes were proportionally similar to those evoked by electrocutaneous foot or shank stimulation, although the latency to onset and peak flexion torques were significantly longer with IM stimulation. In the second experiments, the amplitude and frequency of IM TA stimulation were varied to alter the stimulus-induced muscle torque. Peak ankle and hip torques generated during the flexion reflex responses were correlated to a greater extent with stimulus-induced muscle torques as compared with the modulated stimulus parameters. In the third experimental series, IM stimuli delivered to the gastrocnemius (GS) elicited flexion reflexes in approximately half of the subjects tested. The combined data indicate a potentially prominent role of the stimulus-induced muscle contraction to the magnitude and latency of flexor reflex behaviors after IM TA stimulation. Results after IM GS stimulation indicate multi-joint flexion reflexes can also be elicited, although to a lesser extent than IM TA stimulation.
Presynaptic GABAB Receptors Modulate Thalamic Excitation of Inhibitory and Excitatory Neurons in the Mouse Barrel Cortex
Authors: Porter James T. , Nieves Dalila
Published: July 2004

Cortical inhibition plays an important role in the processing of sensory information, and the enlargement of receptive fields by the in vivo application of GABAB receptor antagonists indicates that GABAB receptors mediate some of this cortical inhibition. Although there is evidence of postsynaptic GABAB receptors on cortical neurons, there is no evidence of GABAB receptors on thalamocortical terminals. Therefore to determine if presynaptic GABAB receptors modulate the thalamic excitation of layer IV inhibitory neurons and excitatory neurons in layers II–III and IV of the somatosensory “barrel” cortex of mice, we used a thalamocortical slice preparation and patch-clamp electrophysiology. Stimulation of the ventrobasal thalamus elicited excitatory postsynaptic currents (EPSCs) in cortical neurons. Bath application of baclofen, a selective GABAB receptor agonist, reversibly decreased AMPA receptor-mediated and N-methyl-d-aspartate (NMDA) receptor-mediated EPSCs in inhibitory and excitatory neurons. The GABAB receptor antagonist, CGP 35348, reversed the inhibition produced by baclofen. Blocking the postsynaptic GABAB receptor-mediated effects with a Cs+-based recording solution did not affect the inhibition, suggesting a presynaptic effect of baclofen. Baclofen reversibly increased the paired-pulse ratio and the coefficient of variation, consistent with the presynaptic inhibition of glutamate release. Our results indicate that the presynaptic activation of GABAB receptors modulates thalamocortical excitation of inhibitory and excitatory neurons and provide another mechanism by which cortical inhibition can modulate the processing of sensory information.
Preparatory Activity in Visual Cortex Indexes Distractor Suppression During Covert Spatial Orienting
Authors: Serences John T. , Yantis Steven , Culberson Andrew , Awh Edward
Published: July 2004

The deployment of spatial attention induces retinotopically specific increases in neural activity that occur even before a target stimulus is presented. Although this preparatory activity is thought to prime the attended regions, thereby improving perception and recognition, it is not yet clear whether this activity is a manifestation of signal enhancement at the attended locations or suppression of interference from distracting stimuli (or both). We investigated the functional role of these preparatory shifts by isolating a distractor suppression component of selection. Behavioral data have shown that manipulating the probability that visual distractors will appear modulates distractor suppression without concurrent changes in signal enhancement. In 2 experiments, functional magnetic resonance imaging revealed increased cue-evoked activity in retinotopically specific regions of visual cortex when increased distractor suppression was elicited by a high probability of distractors. This finding directly links cue-evoked preparatory activity in visual cortex with a distractor suppression component of visual selective attention.
Functional Impact of Alternative Splicing of Human T-Type Cav3.3 Calcium Channels
Authors: Murbartián Janet , Arias Juan Manuel , Perez-Reyes Edward
Published: July 2004

Low-voltage-activated T-type (Cav3) Ca2+ channels produce low-threshold spikes that trigger burst firing in many neurons. The CACNA1I gene encodes the Cav3.3 isoform, which activates and inactivates much more slowly than the other Cav3 channels. These distinctive kinetic features, along with its brain-region-specific expression, suggest that Cav3.3 channels endow neurons with the ability to generate long-lasting bursts of firing. The human CACNA1I gene contains two regions of alternative splicing: variable inclusion of exon 9 and an alternative acceptor site within exon 33, which leads to deletion of 13 amino acids (Δ33). The goal of this study is to determine the functional consequences of these variations in the full-length channel. The cDNA encoding these regions were cloned using RT-PCR from human brain, and currents were recorded by whole cell patch clamp. Introduction of the Δ33 deletion slowed the rate of channel opening. Addition of exon 9 had little effect on kinetics, whereas its addition to Δ33 channels unexpectedly slowed both activation and inactivation kinetics. Modeling of neuronal firing showed that exon 9 or Δ33 alone reduced burst firing, whereas the combination enhanced firing. The major conclusions of this study are that the intracellular regions after repeats I and IV play a role in channel gating, that their effects are interdependent, suggesting a direct interaction, and that splice variation of Cav3.3 channels provides a mechanism for fine-tuning the latency and duration of low-threshold spikes.
Erythroid-induced commitment of K562 cells results in clusters of differentially expressed genes enriched for specific transcription regulatory elements
Authors: Addya Sankar , Keller Margaret A. , Delgrosso Kathleen , Ponte Christine M. , Vadigepalli Rajanikanth , Gonye Gregory E. , Surrey Saul
Published: July 2004

Understanding regulation of fetal and embryonic hemoglobin expression is critical, since their expression decreases clinical severity in sickle cell disease and β-thalassemia. K562 cells, a human erythroleukemia cell line, can differentiate along erythroid or megakaryocytic lineages and serve as a model for regulation of fetal/embryonic globin expression. We used microarray expression profiling to characterize transcriptomes from K562 cells treated for various times with hemin, an inducer of erythroid commitment. Approximately 5,000 genes were expressed irrespective of treatment. Comparative expression analysis (CEA) identified 899 genes as differentially expressed; analysis by the self-organizing map (SOM) algorithm clustered 425 genes into 8 distinct expression patterns, 322 of which were shared by both analyses. Differential expression of a subset of genes was validated by real-time RT-PCR. Analysis of 5′-flanking regions from differentially expressed genes by PAINT v3.0 software showed enrichment in specific transcription regulatory elements (TREs), some localizing to different expression clusters. This finding suggests coordinate regulation of cluster members by specific TREs. Finally, our findings provide new insights into rate-limiting steps in the appearance of heme-containing hemoglobin tetramers in these cells.
Multigenic control of serum adiponectin levels: evidence for a role of the APM1 gene and a locus on 14q13
Authors: Menzaghi C. , Ercolino T. , Salvemini L. , Coco A. , Kim S. H. , Fini G. , Doria A. , Trischitta V.
Published: July 2004

Adiponectin is a circulating enhancer of insulin action that is secreted by the adipose tissue. In epidemiological studies, serum levels of this protein predict the risk of type 2 diabetes and cardiovascular events. Serum adiponectin levels have been associated with variants at the adiponectin (APM1) and PPARγ2 loci and have also been linked to markers on 5p15 and 14q13. We investigated the role of these four loci in regulating serum adiponectin in a Caucasian population from Italy. Four haplotype-tagging single-nucleotide polymorphisms (ht-SNPs) (−11377 C>G, −4041 A>C, +45 T>G, and +276 G>T) at the APM1 locus and the PPARγ2 Pro12Ala polymorphism were examined for association with serum adiponectin in 413 unrelated, nondiabetic individuals. Of the five SNPs tested, +276G>T was the only one to be associated with serum adiponectin ( P = 0.032), with “TT” individuals having higher adiponectin levels than other subjects. In a variance-components analysis of 737 nondiabetic members of 264 nuclear families, adiponectin heritability was 30%, with a small but significant proportion explained by the +276 genotype ( P = 0.0034). Suggestive evidence of linkage with adiponectin levels was observed on chromosome 14q13, with a LOD of 2.92 ( P = 0.000057) after including the APM1 +276 genotype in the model. No linkage was observed at 5p15. Our data indicate a strong genetic control of serum adiponectin. A small proportion of this can be attributed in our population to variability at the APM1 locus, but an as yet unidentified gene on 14q13 appears to play a much bigger role.
The Syntax of Existential Constructions
Authors: Hazout Ilan
Published: July 2004

This article outlines an account of the syntax of existential constructions (e.g., There are [too many problems]) based on a view of the postcopular NPas a predicate. This NPfigures as the predicate in an embedded clausal complement of be with expletivethere as its subject. There consequently moves to the higher Spec, IPposition for Case-theoretic reasons. Existential constructions and existential interpretation are a particular instance of a wider phenomenon involving the use of predicates of various categories with expletive subjects (e.g., It is cold).Long-distance agreement between the main (inflected) verb and the postcopular NPis a combined effect of the relation of subject-predicate agreement holding between the expletive subject (there) and a predicate NPwithin the embedded clausal structure and the relation of specifier-head agreement (feature checking) between the raised expletive and the matrix I/T. This analysis is generalized to other cases of long-distance agreement (e.g., There appeared a man). It is shown that an analysis based on the notionAgree (Chomsky 2000) is empirically inadequate. Well-known restrictions on the distribution of NPs/ DPs in existential constructions follow from the proposed analysis.
Movement under Control
Authors: Boeckx Cedric , Hornstein Norbert
Published: July 2004

We examine the three categories of empirical argument that Landau (2003) puts forward against a movement theory of control (MTC): overgeneration cases, alleged arguments in favor of an MTC, and raising/control contrasts. We show that the problems cited either have plausible alternative analyses that leave the MTC unscathed or, in fact, are not nearly as dire for the MTC as Landau supposes. We conclude that the “standard” theory enjoys no obvious empirical advantages over the MTC and that the MTC is superior on conceptual and methodological grounds.
On the Structure of Resultative Participles in English
Authors: Embick David
Published: July 2004

The article examines the structure of resultative participles in English: participles that denote a state resulting from a prior event, such as The cake is flattened or The metal is hammered.The analysis identifies distinct stative participles that derive from the different heights at which aspectual morphemes attach in a verbalizing structure.The Aspect head involved in resultative participles is shown to attach to a vP that is also found in (a) the formation of deadjectival verbs and (b) verb phrases with resultative secondary predicates, like John hammered the metal flat. These distinct constructions are shown to have a shared structural subcomponent.The analysis proposed here is compared with Lexicalist approaches employing the verbal versus adjectival passive distinction.It is shown that a uniformly syntactic analysis of the participles is superior to the Lexicalist alternative.
Against Bans on Lowering
Authors: Richards Norvin
Published: July 2004

A number of syntactic theories posit explicit bans on lowering operations. Such bans are largely redundant on cyclic approaches to the syntactic derivation, which can rule out most instances of lowering without an explicit ban. I concentrate here on one instance of lowering not ruled out by the cycle, namely, an Agree relation between a probe and a goal in the probe's own specifier. Facts about Bulgarian wh-movement suggest that operations of this kind are available in principle and that lowering therefore should not be banned.
The Emotional Intelligence Profile of Academics in a Merger Setting
Authors: Maree Jacobus G. , Eiselen Riette J.
Published: July 2004

In the past perceived cognitive potential, more than any other factor, was viewed as a predictor for a stable life and future success. The concept of “emotional intelligence” (EI), however, provides a useful instrument to describe the intricate configuration of interrelated factors that play a role in predicting a person’s success in life. Using the merger between the former Pretoria Teacher’s Training College and the University of Pretoria as a backdrop, the research reported in this article attempts to establish the emotional intelligence profiles of academics in a merger setting. The qualitative section of the research involves a study of the literature on certain aspects of the phenomenon “emotional intelligence”, whereas the quantitative part of the research involves the administration of the BarOn EQ-i™ measure to 53 participants who have all been involved in the above-mentioned merger. The results of the study provide statistical evidence of how a drastic life-changing event, such as a “merger” between two higher education institutions, may hamper the actualization of academics’ intellectual potential. The research accentuates the importance of timeous and continued assessment of the ongoing functioning and well-being of academics who have been involved in a merger and it underlines the need for tailor-made training programs that may help improve the emotional skills and functioning of such academics.
The “Significantly Worse” Phenomenon
Authors: Thirunarayanan M. O.
Published: July 2004

Students in central-city schools face many hardships and problems when compared to their suburban counterparts. To a large extent these problems and hardships prevent students in central-city schools from achieving their fullest potential. Students in central-city schools also typically score lower than students in other school locations on national assessments. This study used data from several National Assessment of Educational Progress (NAEP) reports to compare achievement of students in central-city schools, rural schools, and suburban schools in many content areas and in different years. Such comparisons led to the identification of the “Significantly Worse Phenomenon.”
African American Parents’ Educational Orientations
Authors: Diamond John B. , Gomez Kimberley
Published: July 2004

Research on race, social class, and parent involvement in education often implies that parents’ educational orientations result directly from their social class or racial group backgrounds. In this article, the authors study the involvement of working-class and middle-class African American parents. They argue that these parents’ educational orientations are informed by the educational environments they navigate, their resources for negotiating these environments, and their prior social class and race-based educational experiences. Middle-class African American parents studied were more likely to select their children’s schools, assess them favorably, and adopt supportive orientations toward them. In contrast, working-class African American parents studied were assigned to schools, tended to assess them less favorably, and adopted more reform-based orientations toward them. The article extends prior work by studying social class and parent involvement within the African American community and by highlighting the interaction between parents’ perceptions of school context and their educational orientations.
Social Power, Social Status and Perceptual Similarity of Workplace Victimization: A Social Network Analysis of Stratification
Authors: Lamertz Kai , Aquino Karl
Published: July 2004

This article develops and tests a comprehensive social structural model of social power and status effects on victimization in organizations. Victimization focuses on the extent to which individuals perceive themselves to be the target of negative or aggressive behaviors by others. The conceptual framework elucidates how formal and informal status differences associated with access to social powers in three different social networks are related to victimization perceptions. Using dyads as the unit of analysis in a sample of government employees, we find that asymmetric relationships between two actors in the friendship and advice networks, and structural equivalence in the advice and dislike networks are associated with perceptual agreement. The results suggest that stratification in a social system may create the context in which victimization thrives because it affects access to informal forms of social power.
The Toll of Unemployment Does Not Stop with the Unemployed
Authors: Westman Mina , Etzion Dalia , Horovitz Shoshi
Published: July 2004

This study focuses on the crossover of state anxiety between spouses in working couplesin Israel when one of them faces unemployment. We assessed state anxiety, financial hardship and social support for both spouses at two points in time. Participants were 113 unemployed people who came to the Academics Employment Exchange to apply for the ‘unemployment grant’. They and their spouses completed questionnaires at the beginning (wave 1) and end (wave 2) of the 2-month period for which they were entitled to the ‘unemployment grant’. Findings demonstrate that on both occasions, the economic hardship was a positive predictor of anxiety for both the unemployed and their spouses and social support was inversely related to their anxiety. Furthermore, there was a significant bidirectional crossover effect of state anxiety from the unemployed to the spouse and from the spouse to the unemployed at both waves after controlling for all relevant variables. We concluded that prevention programs dealing with the unemployed should take into account the crossover process and incorporate actions for both spouses.
Kindling Activism? Union Commitment and Participation in the UK Fire Service
Authors: Redman Tom , Snape Ed
Published: July 2004

Using survey data from a UK fire service, this article examines the antecedents of members’ intent to participate in their union. The authors identify three dimensions of intent to participate – in rankandfile activities, in militant activitiesand in standing for union office. Affective union commitment is the main direct determinant of all three. Affective union commitment itself reflects solidaristic prounion beliefs and instrumental union commitment, providing some support for interactionist and rational choice theories. There is also evidence of frustration–aggression effects, with perceived industrial relations climate and pay equity having negative direct effects on intent to participate. Perceived industrial relations climate moderates none of these relationships. Implications for union strategy and renewal are discussed.
For Queen and Country? National Frames of Reference in the Talk of Soldiers in England
Authors: Gibson Stephen , Abell Jackie
Published: July 2004

Social scientists frequently use the iconic figure of the soldier who fights and dies for the nation to exemplify the power of processes of national identification. However, little work has considered how soldiers themselves orient to the possibility of being motivated by a desire to ‘serve the country’. The present study explored this through a series of interviews with members of the British Army and Territorial Army. Although in explicit talk about ‘the country’ the soldiers typically downplayed the importance of ‘serving the country’ as motivation, in discussing the prospect of a European army the national basis of armies was taken for granted. The findings are discussed in terms of the problematic nature of displays of English ‘patriotism’ or ‘pride’. It is argued that the relationship between national identity and military service, often assumed to be straightforward in social scientific texts, is oriented to as a delicate issue by soldiers themselves.
Yabba-Dabba-Doo! Evolutionary Psychology and the Rise of Flintstone Psychological Thinking in Organization and Management Studies
Authors: Sewell Graham
Published: July 2004

Seven years have passed since Nigel Nicholson published his manifesto for evolutionary psychology (EP) in Human Relations. Given EP’s continued popularity, this article undertakes a timely reappraisal of its assumptions and practical implications. In particular, it assesses EP’s claim to unify the social and natural sciences by establishing a foundation for psychology in the evolutionary biological sciences. I demonstrate that EP is found wanting in both these areas: it cannot satisfy the rigorous demands of experimental evolutionary biology and does not deal well with some of the key problems faced by mainstream psychologists. As a result, EP’s claims as they pertain to management and organizations are speculative and highly normative, despite vigorous protestations to the contrary.
Collective Outcomes and Social Mobilization in Chilean Employment Initiatives for Women
Authors: Snyder Linda
Published: July 2004

Chilean case studies explore the potential of women’s employment initiatives to foster social mobilization addressing the underlying socio-political factors related to poverty and unemployment. Some insight is provided regarding the emergence of collective endeavours, factors favouring their development, and barriers to social and political involvement.
Human Rights and Social Work in a Transforming Society
Authors: Noyoo Ndangwa
Published: July 2004

This discussion is addressed to the question of human rights in South Africa. It argues that the profession of social work must continue to champion and shape a human rights discourse in the current democratic order.
Child Welfare Programs and Services
Authors: Segal Uma A.
Published: July 2004

This is a comparison of child welfare in the USA and Japan. It identi.es some of the major problems facing children in the two countries, presents policy and legislation relating to children, and explores services and programs available.
Job Security and the Perception of Unemployment among Immigrants
Authors: Kaufman Roni , Mirsky Julia
Published: July 2004

The article studies the occupational security and the perception of the economic situation of Russian immigrants in Israel and other Israelis. Similar rates of job security were found in the two groups. It is suggested that cultural factors and policies of integration of immigrants into the labor force affect these .ndings.
The Integrity of Polymer Composites during and after Fire
Authors: Gibson A. G. , Wright P. N. H. , Wu Y. -S. , Mouritz A. P. , Mathys Z. , Gardiner C. P.
Published: July 2004

This paper reports on changes to the mechanical properties of woven glass laminates with polyester, vinyl ester and phenolic resins during fire exposure. Two sets of experiments were carried out. First, unstressed laminates were exposed to a constant one-sided heat flux (50 kW m 2) for various times, and the residual post-fire strength at room temperature was reported.

In a second series of experiments, laminates were tested under load. The times corresponding to a given loss of properties were 2-3 times shorter than in the previous case. It was found in both cases that modes of loading involving compressive stress were more adversely affected by fire exposure than those involving tension.

A simple ‘two-layer’ model is proposed, in which the laminate is assumed to comprise (i) an unaffected layer with virgin properties and (ii) a heat-affected layer with zero properties. For residual properties after fire, the ‘effective’ thickness of undamaged laminate was calculated using this model and compared with measured values. A thermal model was employed to predict the temperature and the residual resin profile through the laminate versus time. Comparing the model predictions with the measured values of effective laminate thickness enabled simple criteria to be developed for determining the position of the ‘boundary’ between heat-affected and undamaged material. For post-fire integrity of unloaded laminates, this boundary corresponds to a Residual Resin Content (RRC) of 80%, a criterion that applies to all the resin types tested.

For polyester laminate under load in fire, the boundary in compressive loading (buckling failure) appears to correspond to the point where the resin reaches 170 C. In tensile loading, significant strength is retained, because of the residual strength of the glass reinforcement.

The model was used to produce predictions for ‘generic’ composite laminates in fire.
A Burr Type X Chain-of-Links Model for Carbon Fibers
Authors: Surles James G. , D’ambrosio Donna M.
Published: July 2004

A model for application to carbon fibrous composites is proposed based on the Burr type X (BurrX) distribution first proposed by Burr (Burr, I.W. (1942). Annals of Mathematical Statistics, 13: 215-222) with an included parameter to account for fiber length. The model is further generalized similar to the generalization of the Weibull proposed by Padgett et al. (Padgett, W.J., Durham, S.D. and Mason, A.M. (1995). Journal of Composite Materials, 29: 1873-1884). Maximum likelihood estimation is briefly discussed, and the model is applied to the single-filament data of Bader and Priest (Bader, M.G. and Priest, A.M. (1982). In: Hayashi, T., Kawata, K. and Umekawa, S. (eds), Progress in Science and Engineering of Composites, pp. 1129-1136. ICCM-IV, Tokyo).
Determination of the Moisture Uptake Mechanism in Closed Cell Polymeric Structural Foam during Hygrothermal Exposure
Authors: Earl J. S. , Shenoi R. A.
Published: July 2004

Polymer composite sandwich construction is increasingly used in the fabrication of marine craft where high specific strength and stiffness are required. While the moisture uptake behaviour of thermoset resins and their fibre-reinforced composites has been the focus of much research, the mechanisms of moisture absorption in foam core materials have received little attention. This paper presents a programme of work carried out to determine the moisture uptake mechanisms in closed cell PVC foam under fresh-water immersion. A comprehensive understanding of the ageing mechanism for the foam has been proposed. A multi-stage process was observed, which exhibited an initial mass increase that was linear with respect to the square root of time, followed by an apparent saturation plateau, subsequently followed by further increases and plateaus. While diffusion into the polymer cell wall network was found to be the primary mechanism, passage of moisture into cell cavities was also observed. The multi-stage process was attributed to diffusion, influenced by internal stress relaxation and the geometry of the local cell structure. A Fickian one-dimensional diffusion model was found to fit the initial part of the experimental results adequately.
Optimization of Logistic and Manufacturing Systems through Simulation: A Colored Petri Net-Based Methodology
Authors: Piera Miquel Àngel , Narciso Mercedes , Guasch Antoni , Riera Daniel
Published: July 2004

Simulation models have proved to be useful for examining the performance of different system configurations and/or alternative operating procedures for complex logistic or manufacturing systems. However, when applying simulation techniques to increase the performance of those systems, several limitations arise due to their inability to evaluate more than a fraction of the immense range of options available. Simulation-optimization is one of the most popular approaches to improve the use of simulation models as a tool to obtain the best (optimal or quasi-optimal) decision variable values that minimize a certain objective function. However, despite the success of several simulation-optimization packages, many technical barriers still remain. The authors describe a new approach to integrate evaluation (simulation) methods with search methods (optimization) based on not only simulation results but also information from the simulation model.