bluuebunny/crossref_metadata_2025 huggingface dataset:
A Spiking Neuron Model of Cortical Correlates of Sensorineural Hearing Loss: Spontaneous Firing, Synchrony, and Tinnitus
Authors: Dominguez Melissa , Becker Suzanna , Bruce Ian , Read Heather
Published: October 2006

Hearing loss due to peripheral damage is associated with cochlear hair cell damage or loss and some retrograde degeneration of auditory nerve fibers. Surviving auditory nerve fibers in the impaired region exhibit elevated and broadened frequency tuning, and the cochleotopic representation of broadband stimuli such as speech is distorted. In impaired cortical regions, increased tuning to frequencies near the edge of the hearing loss coupled with increased spontaneous and synchronous firing is observed. Tinnitus, an auditory percept in the absence of sensory input, may arise under these circumstances as a result of plastic reorganization in the auditory cortex. We present a spiking neuron model of auditory cortex that captures several key features of cortical organization. A key assumption in the model is that in response to reduced afferent excitatory input in the damaged region, a compensatory change in the connection strengths of lateral excitatory and inhibitory connections occurs. These changes allow the model to capture some of the cortical correlates of sensorineural hearing loss, including changes in spontaneous firing and synchrony; these phenomena may explain central tinnitus. This model may also be useful for evaluating procedures designed to segregate synchronous activity underlying tinnitus and for evaluating adaptive hearing devices that compensate for selective hearing loss.
On the Computational Power of Threshold Circuits with Sparse Activity
Authors: Uchizawa Kei , Douglas Rodney , Maass Wolfgang
Published: October 2006

Circuits composed of threshold gates (McCulloch-Pitts neurons, or perceptrons) are simplified models of neural circuits with the advantage that they are theoretically more tractable than their biological counterparts. However, when such threshold circuits are designed to perform a specific computational task, they usually differ in one important respect from computations in the brain: they require very high activity. On average every second threshold gate fires (sets a 1 as output) during a computation. By contrast, the activity of neurons in the brain is much sparser, with only about 1% of neurons firing. This mismatch between threshold and neuronal circuits is due to the particular complexity measures (circuit size and circuit depth) that have been minimized in previous threshold circuit constructions. In this letter, we investigate a new complexity measure for threshold circuits, energy complexity, whose minimization yields computations with sparse activity. We prove that all computations by threshold circuits of polynomial size with entropy O(log n) can be restructured so that their energy complexity is reduced to a level near the entropy of circuit states. This entropy of circuit states is a novel circuit complexity measure, which is of interest not only in the context of threshold circuits but for circuit complexity in general. As an example of how this measure can be applied, we show that any polynomial size threshold circuit with entropy O(log n) can be simulated by a polynomial size threshold circuit of depth 3.

Our results demonstrate that the structure of circuits that result from a minimization of their energy complexity is quite different from the structure that results from a minimization of previously considered complexity measures, and potentially closer to the structure of neural circuits in the nervous system. In particular, different pathways are activated in these circuits for different classes of inputs. This letter shows that such circuits with sparse activity have a surprisingly large computational power.
A Model for Perceptual Averaging and Stochastic Bistable Behavior and the Role of Voluntary Control
Authors: Koene Ansgar R.
Published: October 2006

We combine population coding, winner-take-all competition, and differentiated inhibitory feedback to model the process by which information from different, continuously variable signals is integrated for perceptual awareness. We focus on “slant rivalry,” where binocular disparity is in conflict with monocular perspective in specifying surface slant. Using a robust single parameter set, our model successfully replicates three key experimental results: (1) transition from signal averaging to bistability with increasing signal conflict, (2) change in perceptual reversal rates as a function of signal conflict, and (3) a shift in the distribution of percept durations through voluntary control exertion. Voluntary control is implemented through the use of a single top-down bias input. The transition from signal averaging to bistability arises as a natural consequence of combining population coding and wide receptive fields, common to higher cortical areas. The model architecture does not contain any assumption that would limit it to this particular example of stimulus rivalry. An emergent physiological interpretation is that differentiated inhibitory feedback may play an important role for increasing percept stability without reducing sensitivity to large stimulus changes, which for bistable conditions leads to increased alternation rate as a function of signal conflict.
Do Adolescents Engage in Delinquency to Attract the Social Attention of Peers? An Extension and Longitudinal Test of the Social Reinforcement Hypothesis
Authors: Rebellon Cesar J.
Published: October 2006

Although social-learning theory remains among the dominant perspectives in micro-level research concerning the causes of delinquency, research has yet to provide an adequate test of its social-reinforcement component using the methods required by the logic of operant psychology. The present article discusses the limits of existing attempts to test the social-reinforcement hypothesis, offers a new approach for testing it, and describes the use of panel data to provide such a test. In particular, the author examined (1) whether delinquency increases the amount of time a perpetrator's peers choose to spend with him or her, (2) whether such attention serves as a direct reinforcement prompting further delinquency from the perpetrator, and (3) whether such attention serves as a vicarious reinforcement prompting delinquency from audience members in proportion to their desire for informal socializing among peers. The results suggest support for vicarious, but not direct, social reinforcement.
The Impact of Community Disadvantage on the Relationship between the Family and Juvenile Crime
Authors: Hay Carter , Fortson Edward N. , Hollist Dusten R. , Altheimer Irshad , Schaible Lonnie M.
Published: October 2006

Prior research on the family has identified many variables significantly associated with criminal involvement, including such things as parental supervision and discipline and the quality of the parent-child relationship. However, little attention has been devoted to the possibility that the effects of these variables on crime depend on characteristics of the social context in which a family resides. Using data from a national sample of adolescents, the authors examined how the effects of key family variables depend on two indicators of a community's level of disadvantage: its objective level of community poverty (as indicated by U.S. census data) and its perceived inadequacy as a place to raise children (as rated by parents). The analysis suggests that community disadvantage significantly amplifies the effects on crime of problems in the family environment. The implications of this conclusion for criminological theory and future research on the causes of crime are addressed.
How General Is General Strain Theory? Assessing Determinacy and Indeterminacy across Life Domains
Authors: De Coster Stacy , Kort-Butler Lisa
Published: October 2006

This article explores how assumptions of determinacy and indeterminacy apply to general strain theory. Theories assuming determinacy assert that motivational conditions determine specific forms of deviant adaptations, whereas those assuming indeterminacy propose that a given social circumstance can predispose a person toward many forms of deviance. The authors propose that strain theory posits a strong tendency for the domains in which stresses occur to match those in which delinquency takes place. This is a source of determinacy. Drawing on stress spillover and aggression displacement arguments, the authors also discuss sources of indeterminacy—or domain crossover effects. The tendency toward domain matching that is tempered by stress spillover and aggression displacement is what the authors refer to as soft determinacy. The authors derive hypotheses from their soft determinacy argument and test them on a sample of middle school students. The results support the arguments and suggest that discussion of soft determinacy is worthy of further attention.
“I Ain't Gonna Let No One Disrespect Me”
Authors: Stewart Eric A. , Schreck Christopher J. , Simons Ronald L.
Published: October 2006

The authors extended Elijah Anderson's “code of the street” thesis to explain victimization among a longitudinal sample of 720 African American adolescents from 259 neighborhoods. Specifically, the authors assessed whether the street code promotes greater safety or aggravates the risk for victimization. Anderson portrayed the code of the street, which encourages individuals to appear aggressive and tough, as an adaptation necessary for safely functioning in a disadvantaged, high-crime community. He theorized that adopting the street code promotes respect among one's peers and would-be attackers, thereby increasing one's safety against victimization. The authors found no support for the idea that adopting the street code reduces victimization. Instead, their findings suggest that individuals who adopt the street code have higher levels of victimization. Furthermore, adopting the street code exacerbates the risk for victimization beyond what would be the case from living in a dangerous and disorganized neighborhood.
A Life-Course Analysis of the Criminogenic Effects of Maternal Cigarette Smoking During Pregnancy
Authors: McGloin Jean Marie , Pratt Travis C. , Piquero Alex R.
Published: October 2006

Research from a variety of disciplines indicates that maternal cigarette smoking (MCS) during pregnancy is associated with an array of problematic outcomes, including various measures of criminal offending. Although some researchers have applied Moffitt's developmental taxonomy as a framework for understanding this relationship, this line of research has treated MCS as a proxy for neuropsychological deficit rather than a precursor to it. In short, no research has yet tested whether neuropsychological deficit in fact mediates the relationship between MCS and life-course-persistent offending. Using longitudinal data on an inner-city African American cohort, this research found no evidence of such a mediating relationship. The empirical and theoretical implications of these findings are discussed in the context of identifying pathways for future research.
The Love of a Good Man? Romantic Relationships as a Source of Support or Hindrance for Female Ex-Offenders
Authors: Leverentz Andrea M.
Published: October 2006

This article explores the impact of romantic relationships on the reentry experiences of female ex-offenders. Although attachment to a prosocial spouse is an important social bond in the desistance of male offenders, male and female offenders have different offending and life experiences and are likely to draw romantic partners from very different groups. This article addresses this issue through an analysis of qualitative interviews with 49 female ex-offenders and their romantic partners. These women most often have relationships with recovering drug users and/or ex-offenders, not purely prosocial men or women. These relationships are dynamic and may be both destructive and conventionalizing at different points in time. Many women also consciously avoid romantic relationships, at least temporarily. These patterns of romantic relationships for female ex-offenders add to our understanding of the role of social bonds in desistance. This article emphasizes the need to look at relationships as processes rather than static events and to expand the definition of prosocial partners.
Is clozapine—aripiprazole combination a useful regime in the management of treatment-resistant schizophrenia?
Authors: Karunakaran Kanapathippillai , Tungaraza Tongeji E. , Harborne Giles C.
Published: October 2006

Around 40—70% patients with treatment-resistant schizophrenia fail to respond to clozapine. Though combining antipsychotics is commonly practised with non-responders, there is Little evidence for its use.

We carried out a retrospective review of case notes of patients with treatment-resistant schizophrenia on clozapine—aripiprazole combination at our clozapine clinic. We report changes in psychotic symptoms, social function, weight, total cholesterol, serum glucose, HDL, CGI and GAF score pre- and post-aripiprazole augmentation.

Clozapine—aripiprazole combination was associated with 22% reduction of clozapine dose. Eighteen out of 24 (75%) Lost a mean weight of 5.05 kg. There was improvement in positive and negative symptoms, sociaL functions, weight Loss and a moderate increase in HDL. Our findings suggest that clozapine—aripiprazole is a safe and tolerable combination; however, controL trials are needed to validate our findings.
Cost effectiveness of olanzapine in prevention of affective episodes in bipolar disorder in the United Kingdom
Authors: McKendrick J. , Cerri K.H. , LLoyd A. , D'AusiLio A. , Dando S. , Chinn C.
Published: October 2006

This study evaLuated the cost effectiveness of oLanzapine compared with lithium as maintenance therapy for patients with bipoLar I disorder (BP1) in the UK.

A Markov model was deveLoped to assess costs and outcomes from the perspective of the UK National HeaLth Service over a 1-year period. Patients enter the modeL after stabilization of a manic episode and are then treated with olanzapine or lithium. Using the findings of a recent randomized clinical trial, the modeL considers the monthly risk of manic or depressive episodes and of dropping out from allocated therapy. Health care resources associated with acute episodes were derived primarily from a recent UK chart review. Costs of maintenance therapy and monitoring were also considered. Key factors influencing cost effectiveness were identified and included in a stochastic sensitivity analysis.

The model estimated that, compared to lithium, olanzapine significantly reduced the annual number of acute mood episodes per patient from 0.81 to 0.58 (difference —0.23; 95% CI: —0.34, —0.12). Per patient average annual care costs fell by £799 (95% CI: —£1,824, £59) driven by reduced inpatient days — but the cost difference was not statistically significant. Sensitivity analysis found the results to be robust to plausible variation in the model's parameters.

The model estimated that using olanzapine instead of lithium as maintenance therapy for BP1 would significantly reduce the rate of acute mood events resulting in reduced hospital costs. Based on available evidence, there is a high likelihood that olanzapine would reduce costs of care compared to lithium.
Altered expression of synaptic protein mRNAs in STOP (MAP6) mutant mice
Authors: Eastwood Sharon L. , Lyon Louisa , George Lydia , Andrieux Annie , Job Didier , Harrison Paul J.
Published: October 2006

Stable tubule-only polypeptide (STOP) proteins are a family of microtubule associated proteins (MAPs) important in microtubule stabilization. Data indicating a role for microtubules in synaptic function has come from studies of the STOP null mouse, which exhibits synaptic deficits, in association with behavioural changes that are alleviated by antipsychotic treatment. These findings suggested that STOP mutant mice may be useful in studies of synaptic function, and could be especially relevant to schizophrenia, postulated to be a disorder of the synapse. Moreover, a genetic association between STOP and schizophrenia has been reported. This study aimed to further characterize synaptic alterations in STOP null and heterozygous mice. Using in situ hybridization histochemistry, the mRNA expression of three pre-synaptic (synaptophysin; growth associated protein-43 (GAP-43); vesicular glutamate transporter-1 (VGlut1)) and two post-synaptic (spinophilin; MAP2) proteins, was quantified in female STOP null ( n = 7), heterozygous ( n = 5) and wild type ( n = 6) mice. For STOP null and heterozygous mice, synaptophysin, VGlut1, GAP-43 and spinophilin mRNAs were decreased in the hippocampus, whilst in addition in the null mice, synaptophysin, VGlut1 and spinophilin mRNAs were decreased in the cerebellum. Alterations in synaptic protein mRNA expression were also detected in the frontal and occipital cortex. MAP2 mRNA expression was unchanged in all brain regions. The profile of mRNA changes is broadly similar to that observed in schizophrenia. Together the data provide supporting evidence for a role for microtubules in synaptic function, and suggest that STOP, or other microtubule proteins, may contribute to the synaptic pathology of schizophrenia.
Alterations of glucose metabolism during treatment with clozapine or amisulpride: results from a prospective 16-week study
Authors: Rettenbacher Maria A. , Hummer Martina , Hofer ALex , Baumgartner Susanne , Ebenbichler Christoph , EdLinger Monika , Kemmler Georg , Lechleitner Monika , Wolfgang Fleischhacker W.
Published: October 2006

Although second-generation antipsychotics have notabLe benefits as compared to typical antipsychotics, their use has been associated with metaboLic disturbances, such as alterations of glucose homeostasis. It is still being debated whether this is a class effect of second-generation antipsychotics.

We conducted a prospective, open study comparing body weight, parameters of insuLin resistance in schizophrenia patients treated with either clozapine ( n = 10) or amisuLpride ( n = 12). All parameters were assessed monthly over a period of 12 to 16 weeks. Body mass index (BMI), fasting serum insulin Levels and the Homeostasis Model Assessment (HOMA) index for insulin resistance increased significantly in patients treated with clozapine. None of these parameters increased significantly in patients treated with amisulpride.

This study indicates that treatment with clozapine appears to have a higher risk to Lead to metabolic disturbances than amisupride.
Effects of olanzapine in male rats: enhanced adiposity in the absence of hyperphagia, weight gain or metabolic abnormalities
Authors: Cooper G.D. , Pickavance L.C. , Wilding J.P.H. , HarroLd J.A. , HaLford J.C.G. , Goudie A.J.
Published: October 2006

Many of olanzapine's (OLZ) actions in humans related to weight regulation can be modelled in female rats (Cooper et al., 2005). Such effects include weight gain, hyperphagia, enhanced visceral adiposity and elevated Levels of insulin and adiponectin. As sex differences have been reported in the effects of antipsychotic drugs, including OLZ, in rats, the current study extended our study in female rats by directly comparing the actions of OLZ in maLes using identical methodology. Individually housed male Han Wistar rats were administered OLZ twice daily (i.p.), at 0, 1, 2, and 4 mg/kg over 21 days. Both differences from, and simiLarities to, the data obtained in females were obtained. Males treated with OLZ showed reduced weight gain, enhanced visceral adiposity and reduced Lean muscle mass. There were no accompanying changes in food or water intake. OLZ did not induce changes in plasma Levels of insulin, Leptin or gLucose. Significant elevation of adiponectin was observed. OLZ-treated males dispLayed elevated prolactin and suppressed testosterone. OLZ's effects in humans can very clearly be most validly modelled in female rats, although the cause(s) of the sex difference in OLZ's actions in rats are not clear. However, the finding that significantly enhanced adiposity is seen in both male and female rats, in other animal species (mice and dogs) and in humans suggests that studies in male rats of OLZ's effects may be of value, by highlighting the consistent ability of OLZ to increase visceral adiposity. It is hypothesized that such adiposity is a key, clinically relevant, common component of OLZ's actions which may be, at Least partially, independent of both OLZinduced weight gain and hyperphagia, and which is induced reliably in male and female rats and other animal species. Possible mechanisms involved in the effects reported are discussed.
Synergistic Flame Retardant Effect of SiO2in LLDPE/EVA/ATH Blends
Authors: Wei Ping , Han Zhidong , Xu Xiaonan , Li Zhanxiong
Published: October 2006

SiO2 has long been recognized as an inert diluent and usually used as an enhancing agent in thermoplastic polymers. Few reports are presented about its use as additive flame retardant. In this article, the flame retardant synergistic effect of SiO2 with aluminum hydroxide (ATH) on linear low density polyethylene and ethylene-vinyl acetate (LLDPE/EVA) composites in the presence of a new compatibilizer, polyethylene (PE) grafted by fluoropolysiloxane (FS), prepared to improve the compatibility between polymers (LLDPE/EVA) and inorganic fillers (ATH and SiO2), is investigated by means of limited oxygen index (LOI), cone calorimeter (CONE) and thermogravimetric analysis (TGA). The results show that the addition of SiO2apparently increases the LOI value and decreases the heat release rate (HRR), mass loss rate (MLR), and specific extinction area (SEA). The TGA data shows further evidence that the synergistic mechanism of SiO2 with ATH is mainly due to the physical process in the condensed phase leading to the formation of a more stable and compact barrier, which efficiently prevents the heat and mass transfer in fire. The good mechanical properties of the flame retardant materials implies the improved compatibility by the newly prepared compatibilizer.
Synergism of GUP and Boric Acid Characterized by Cone Calorimetry and Thermogravimetry
Authors: Gao Ming , Niu Jincheng , Yang Rongjie
Published: October 2006

Wood is treated with a new composite flame retardant, whose components guanyl urea phosphate (GUP) and boric acid (BA) impart flame retardance. The flame retarding behavior of these samples is measured by cone calorimeter. The thermal behavior of samples has been studied by differential thermogravimetry (DTG) and thermogravimetry (TG) in air. The activation energies for different stages of thermal degradation are obtained following the method of Broido, A. (1969). J. Polym. Sci., Part 2, 7: 1761. It is found that the combustion parameters of wood, including rate of heat release (RHR) and total heat release (THR) are decreased considerably by the treatment, especially for wood treated with the composite flame retardant of wood (FRW) because of a strong synergistic effect of flame retardance between GUP and boric acid. The mechanism of synergism is explained by analyzing the TG data. The GUP can accelerate dehydration and carbonization while BA can relatively increase thermal stabilization of wood. Their synthetical actions result in more char and less flammable volatile products, obtaining good flame retardance.
Smoke Movement in a Compartmental Fire
Authors: Chow W. K. , Yin R.
Published: October 2006

Transport of larger smoke particles generated by a fire in a compartment is studied. An atrium fire with three different heat release rates is taken as an example. The air flow pattern and temperature contours are predicted by a fire field (or application of computational fluid dynamics (CFD) model. The paths of smoke particles are modeled by the Lagrangian method coupled with the air movement induced by hot smoke. Distribution of smoke particles and their trajectories are then calculated. By superimposing the trajectories of particles of different sizes, the shape of the smoke plume is observed.
Evaluation of Thermal Performance of Flame-resistant Fabrics Considering Thermal Wave Influence in Human Skin Model
Authors: Zhu Fang-Long , Zhang Wei-Yuan
Published: October 2006

A thermal wave skin model incorporating surface heat flux from a skin simulant sensor is developed to characterize the thermal performance of flame-resistant (FR) fabrics covering the skin simulant sensor. Comparison of the results of time to 2nd degree skin burn and temperature elevation of skin beneath a layer of fabric obtained from the newly developed thermal wave skin model to the results obtained by using the Pennes' equation is performed in this research. Results of tolerance time from Stoll criterion method are also compared with Henriques burn damage integral from two skin models between constant–flux exposures in TPP calorimeter. Investigations have been conducted to find the effects of structural parameter, air pressure, and air layer thickness on the thermal performance of the selected FR fabric determined by the newly developed skin model and the method. It is concluded that the thermal protective performance of FR fabrics can be characterized here more precisely than in previous work.
Fire Retardancy of Polyureas
Authors: Costache Marius C. , Kanugh Eric M. , Wilkie Charles A. , Sorathia Usman
Published: October 2006

In this study, a variety of additives have been evaluated as potential fire retardants for polyureas with cone calorimetry being the method of evaluation. The additives that have been evaluated include minerals (alumina trihydrate), bromine-, nitrogen-, and phosphorus-based fire retardants. The major criteria for evaluation are the reductions in the peak heat release rate and the total heat released, the evolution of smoke and dripping.
Dynamic–Mechanical Properties of Wood–Fiber Reinforced Polylactide: Experimental Characterization and Micromechanical Modeling
Authors: Bogren Karin M. , Gamstedt E. Kristofer , Neagu R. Cristian , AÅkerholm Margaretha , LindstroÖm Mikael
Published: October 2006

Wood-fiber reinforced polylactide is a biodegradable composite where both fibers and matrix are from renewable resources. When designing new materials of this kind, it is useful to measure the influence of fiber–matrix interface properties on macroscopic mechanical properties. In particular, a quantitative measure of the dynamic stress transfer between the fibers and the matrix when the material is subjected to cyclic loading would simplify the development of wood-fiber composites. This is obtained by comparing the mechanical dissipation of the composite with a value predicted by a viscoelastic micromechanical model based on perfect interfacial stress transfer. The loss factors predicted by the model are 0.12 and 0.16 at dry and humid conditions, respectively, which amount to 63 and 66% of the experimentally determined values. For Young's moduli the predicted values are 1.01 and 0.88 GPa, which correspond to 92% of the experimentally determined values. The mismatch between the predicted and experimental values may be attributed to imperfect interfaces with restrained stress transfer. Loss factors are also determined for specific molecular bonds using dynamic Fourier transform infrared (FT-IR) spectroscopy. These values show the same trends with regard to moisture content as the macroscopically determined loss factors.
Injection Molding of Postconsumer Wood–Plastic Composites II: Mechanical Properties
Authors: Gosselin R. , Rodrigue D. , Riedl B.
Published: October 2006

ABSTRACT: In the first part of this study, fiber-reinforced microcellular foams were produced via injection molding to study their morphological properties as a function of mold temperature as well as wood, blowing agent, and coupling agent concentrations. Yellow birch wood fibers are added to a recycled postconsumer HDPE/PP matrix (85: 15 ratio) in proportions ranging from 0 to 40 wt% and then foamed with a chemical blowing agent. Maleic-anhydride-polypropylene copolymer (MAPP) is also used as a coupling agent in proportions ranging from 0 to 10 wt% of wood content. In this second part, the mechanical properties in flexion, torsion, and traction are presented.
Progressive Damage Modeling of an Adhesively Bonded Unidirectional Composite Single-lap Joint in Tension at the Mesoscale Level
Authors: Apalak Z. Gul , Apalak M. Kemal , Genc M. Serdar
Published: October 2006

ABSTRACT: This study investigates initiation and propagation of damage zones in the composite plates of an adhesively bonded single-lap joint in tension at the mesoscale level. A set of material degradation rules is applied to the mechanical properties of each failed ply of the plates based on the Hashin failure criterion. The von Mises stress concentrates along the free edges of the adhesive layer and the corresponding lower and upper plate regions and peaks along the free edges of the adhesive–plate interfaces. Consequently, the damage initiates at the lower plate interface to the adhesive layer and propagates in the first ply along this adhesive free edge, and then spreads through the neighboring plies of the lower plate in a similar failure mechanism. The damage in the lower plate occurs in the matrix, delamination, and fiber–matrix failure modes, and the first ply-failure loads decrease significantly with increasing ply fiber angle. Tension tests showed that the adhesive joints with ply lay-ups between [0]10 and [15]10 fails through the adhesive layer, and the lower plates with larger fiber angles break along the free edge of the lower plate– adhesive interface whereas the adhesive layer is still intact. The adhesive failure is interfacial around the adhesive free edges and is through the adhesive in the middle of the overlap region in the joints with the ply lay-ups [0]10. Although a similar failure mechanism is observed in the ply lay-up [15]10, the damage zones in the first ply of the lower plate in which the matrix and fibers are damaged, are distributed in the overlap region. The damage is initiated in the first ply of the lower plate of the adhesive joints with the ply lay-ups [30–90]10 and propagated through the matrix in the fiber direction, and then the lower plate is broken. The present failure model predicts reasonably the initiation and propagation of the damage in the adhesively bonded single-lap joints in tension.
Effects of Particle Size on Melt Viscoelastic Properties During Capillary Extrusion of Glass Bead-filled LDPE Composites
Authors: Liang Ji-ZHAO
Published: October 2006

ABSTRACT: In this study, the viscoelastic properties of a low-density polyethylene (LDPE) filled with glass beads (GBs) are measured at 150 C by means of a capillary rheometer to identify the effect of the particle size on the melt viscoelasticity. The volume fraction of the GB was 8.4%. The surface of the particles has been treated with a silane-coupling agent and the diameter range was from 4 to 180 mm. The results showed that either the entry pressure drop (Pen) or the entry elongation stress (e) is a linear function of shear stress (w) at the channel wall. The values of both Pen and e of these composite melts are close to each other. This illustrates that the influence of the bead size and its distribution on them is insignificant at low filler concentration. The die-swell ratio (B) increases nonlinearly with an addition of w. When the diameter (d) of the beads is less than 50 mm, B decreases dramatically with an increase of d, especially at low shear stress level, and then it decreases slightly under the given shear stress level.
Idiopathic CD4+ T lymphocytopenia is associated with increases in immature/transitional B cells and serum levels of IL-7
Authors: Malaspina Angela , Moir Susan , Chaitt Doreen G. , Rehm Catherine A. , Kottilil Shyam , Falloon Judith , Fauci Anthony S.
Published: October 2006

Idiopathic CD4+ T lymphocytopenia (ICL) is a rare heterogeneous disorder defined by CD4+ T-cell counts below 300 cells/μL in the absence of human immunodeficiency virus (HIV) infection or other known immune deficiency disorders. Here, we report the expansion of immature/transitional B cells in patients with ICL, which is associated with elevated serum levels of IL-7. Both the percentage of immature/transitional B cells and levels of IL-7 were inversely correlated with levels of CD4+ T-cell counts and directly correlated to each other. Further analyses of B cells indicated that, in contrast to the activating effects of HIV disease on mature B cells, the expansion of immature/transitional B cells in patients with ICL occurred at the expense of memory B cells. These findings extend previous reports on primary immunodeficiencies as well as HIV disease by suggesting that CD4+ T-cell lymphopenia has an impact on human B-cell development either directly or indirectly via the associated elevation of IL-7 levels.
Alterations of exhaled nitric oxide in pre-term infants with chronic lung disease
Authors: Roiha H. L. , Kuehni C. E. , Zanolari M. , Zwahlen M. , Baldwin D. N. , Casaulta C. , Nelle M. , Frey U.
Published: October 2006

Animal models suggest that reduced nitric oxide (NO) synthase activity results in lower values of exhaled NO (eNO) present at birth in those individuals who are going to develop chronic lung disease of infancy (CLDI).

Online tidal eNO was measured in 39 unsedated pre-term infants with CLDI (mean gestational age (GA) 27.3 weeks) in comparison with 23 healthy pre-term (31.6 weeks) and 127 term infants (39.9 weeks) at 44 weeks post-conceptional age, thus after the main inflammatory response. NO output (NO output (V′NO) = eNO×flow) was calculated to account for tidal- flow-related changes. Sex, maternal atopic disease and environmental factors (smoking, caffeine) were controlled for.

The mean eNO was not different (14.9 ppb in all groups) butV′NOwas lower in CLDI compared with healthy term infants (0.52versus0.63 nL·s-1). Values for healthy pre-term infants were between these two groups (0.58 nL·s-1). Within all pre-term infants (n = 62),V′NOwas reduced in infants with low GA, high clinical risk index for babies scores and longer duration of oxygen therapy but not associated with post-natal factors, such as ventilation or corticosteroid treatment.

After accounting for flow, the lower nitric oxide output in premature infants with chronic lung disease of infancy is consistent with the hypothesis of nitric oxide metabolism being involved in chronic lung disease of infancy.
Clarithromycin in the treatment of RSV bronchiolitis: a double-blind, randomised, placebo-controlled trial
Authors: Tahan F. , Ozcan A. , Koc N.
Published: October 2006

Respiratory syncytial virus (RSV) bronchiolitis is the most common lower respiratory tract infection in infancy. To date, there is no effective therapy for RSV bronchiolitis.

In order to investigate the efficacy of clarithromycin in the treatment of RSV bronchiolitis, the present authors conducted a randomised, double-blind, placebo-controlled trial comparing clarithromycin with placebo in 21 infants with a diagnosis of RSV bronchiolitis. The infants were randomised to receive clarithromycin or placebo daily for 3 weeks. Levels of interleukin (IL)-4, IL-8, eotaxin, and interferon-γ were determined in plasma, before and after treatment, using ELISA. Six months after treatment, parents were surveyed as to whether their child had experienced wheezing within the previous 6 months.

Treatment with clarithromycin was associated with a statistically significant reduction in the length of hospital stay, the duration of need for supplemental oxygen and the need for β2-agonist treatment. There were significant decreases in plasma IL-4, IL-8 and eotaxin levels after 3 weeks of treatment with clarithromycin. Readmission to the hospital within 6 months after discharge was significantly lower in the clarithromycin group.

In conclusion, clarithromycin has statistically significant effects on the clinical and laboratory findings in respiratory syncytial virus bronchiolitis. Therefore, clarithromycin treatment may be helpful in reducing the short-term effects of respiratory syncytial virus bronchiolitis.
α1-Antitrypsin inhalation reduces airway inflammation in cystic fibrosis patients
Authors: Griese M. , Latzin P. , Kappler M. , Weckerle K. , Heinzlmaier T. , Bernhardt T. , Hartl D.
Published: October 2006

The airways of cystic fibrosis (CF) patients are characterised by neutrophils that release high amounts of elastase overwhelming the local antiprotease shield. Inhalation of α1-antitrypsin (AAT) may restore the protease–antiprotease balance and attenuate airway inflammation in CF airways. The aims of the present study were: 1) to assess the best deposition region for inhaled AAT by two different inhalation strategies; and 2) to examine the effect of 4 weeks of AAT inhalation on lung function, protease–antiprotease balance and airway inflammation in CF patients.

In a prospective, randomised study, 52 CF patients received a daily deposition by inhalation of 25 mg AAT for 4 weeks targeting their peripheral or bronchial compartment. The levels of elastase activity, AAT, pro-inflammatory cytokines, neutrophils, immunoglobulin G fragments and the numbers ofPseudomonas aeruginosawere assessed in induced sputum before and after the inhalation period.

Inhalation of AAT increased AAT levels and decreased the levels of elastase activity, neutrophils, pro-inflammatory cytokines and the numbers ofP. aeruginosa. However, it had no effect on lung function. No difference was found between the peripheral and bronchial inhalation mode.

In conclusion, although no effect on lung function was observed, the clear reduction of airway inflammation after α1-antitrypsin treatment may precede pulmonary structural changes. The α1-antitrypsin deposition region may play a minor role for α1-antitrypsin inhalation in cystic fibrosis patients.
Differences in proteoglycan deposition in the airways of moderate and severe asthmatics
Authors: Pini L. , Hamid Q. , Shannon J. , Lemelin L. , Olivenstein R. , Ernst P. , Lemière C. , Martin J. G. , Ludwig M. S.
Published: October 2006

Excess deposition of proteoglycans (PGs) has been described in the subepithelial layer of the asthmatic airway wall. However, less is known about deposition in the airway smooth muscle (ASM) layer, and whether the pattern of deposition is altered depending upon disease severity.

Endobronchial biopsies were performed in patients with severe or moderate asthma (defined using American Thoracic Society criteria) and in control subjects. Biopsies were immunostained for the PGs biglycan, lumican, versican and decorin. PG deposition was measured in the subepithelial and ASM layers, the former by calculating the area of positive staining, and the latter by determining the percentage area stained using point counting.

Immunostaining for PGs was prominent in biopsies from both moderate and severe asthmatics, compared with control subjects. While there was no difference in the amount of PG in the subepithelial layer between the two asthmatic groups, the percentage area of biglycan and lumican staining in the ASM layer was significantly greater in moderateversussevere asthmatics.

Differences in the deposition of proteoglycans within the airway smooth muscle layer of moderateversussevere asthmatics potentially impact on the functional behaviour of the airway smooth muscle in these two groups of patients.
Modification of surface antigens in blood CD8+ T-lymphocytes in COPD: effects of smoking
Authors: Koch A. , Gaczkowski M. , Sturton G. , Staib P. , Schinköthe T. , Klein E. , Rubbert A. , Bacon K. , Waβermann K. , Erdmann E.
Published: October 2006

In contrast to the effects of cigarette smoke on T-lymphocyte subsets in the airways, it has not yet been determined whether smoking has immunomodulatory effects on surface antigens of peripheral blood T-lymphocytes and, if that is the case, whether these effects differ in smokers with and without chronic obstructive pulmonary disease (COPD).

The present authors have, therefore, examined the expression of the surface activation marker CD28, the levels of cytotoxic effector lymphocytes (CD27-/CD45RA+) and the expression of the lung type (Tc)1-specific chemokine receptor CXCR3+ on peripheral blood CD8+ T-lymphocytes. The present authors have also studied the chemotactic activity of CD8+ T-lymphocytes on monocyte chemotactic protein (MCP)-1 and compared 13 nonsmoking controls, 12 smokers with COPD and 14 smokers without airflow limitation.

There was a decrease in the total count of CD8+ T-cells and an increase in the CD4+/CD8+ ratio in smokers with COPD compared with smokers without COPD and controls. Expression of the Tc1-specific chemokine receptor CXCR3+ by CD8+ T-cells was increased in smokers with COPD compared with smokers without COPD and controls.

The expression of activated and of cytotoxic effector CD8+ T-cells in smokers with and without COPD showed an increase compared with controls. CD8+ T-cells from smokers with and without COPD showed a decrease in chemotactic activity to MCP-1 compared with controls.

In conclusion, chronic obstructive pulmonary disease may be a systemic immunomodulatory disease associated with the modification of surface antigens in blood CD8+ T-lymphocytes.
Analysis and functional annotation of expressed sequence tags from the fall armyworm Spodoptera frugiperda
Authors: Deng Youping , Dong Yinghua , Thodima Venkata , Clem Rollie J , Passarelli A Lorena
Published: October 2006

Background

Little is known about the genome sequences of lepidopteran insects, although this group of insects has been studied extensively in the fields of endocrinology, development, immunity, and pathogen-host interactions. In addition, cell lines derived from Spodoptera frugiperda and other lepidopteran insects are routinely used for baculovirus foreign gene expression. This study reports the results of an expressed sequence tag (EST) sequencing project in cells from the lepidopteran insect S. frugiperda, the fall armyworm.

Results

We have constructed an EST database using two cDNA libraries from the S. frugiperda-derived cell line, SF-21. The database consists of 2,367 ESTs which were assembled into 244 contigs and 951 singlets for a total of 1,195 unique sequences.

Conclusion

S. frugiperda is an agriculturally important pest insect and genomic information will be instrumental for establishing initial transcriptional profiling and gene function studies, and for obtaining information about genes manipulated during infections by insect pathogens such as baculoviruses.
Status of national health research systems in ten countries of the WHO African Region
Authors: Kirigia Joses M , Wambebe Charles
Published: October 2006

Background

The World Health Organization (WHO) Regional Committee for Africa, in 1998, passed a resolution (AFR/RC48/R4) which urged its Member States in the Region to develop national research policies and strategies and to build national health research capacities, particularly through resource allocation, training of senior officials, strengthening of research institutions and establishment of coordination mechanisms.

The purpose of this study was to take stock of some aspects of national resources for health research in the countries of the Region; identify current constraints facing national health research systems; and propose the way forward.

Methods

A questionnaire was prepared and sent by pouch to all the 46 Member States in the WHO African Region through the WHO Country Representatives for facilitation and follow up. The health research focal person in each of the countries Ministry of Health (in consultation with other relevant health research bodies in the country) bore the responsibility for completing the questionnaire. The data were entered and analysed in Excel spreadsheet.

Results

The key findings were as follows: the response rate was 21.7% (10/46); three countries had a health research policy; one country reported that it had a law relating to health research; two countries had a strategic health research plan; three countries reported that they had a functional national health research system (NHRS); two countries confirmed the existence of a functional national health research management forum (NHRMF); six countries had a functional ethical review committee (ERC); five countries had a scientific review committee (SRC); five countries reported the existence of health institutions with institutional review committees (IRC); two countries had a health research programme; and three countries had a national health research institute (NHRI) and a faculty of health sciences in the national university that conducted health research. Four out of the ten countries reported that they had a budget line for health research in the Ministry of Health budget document.

Conclusion

Governments of countries of the African Region, with the support of development partners, private sector and civil society, urgently need to improve the research policy environment by developing health research policies, strategic plans, legislations, programmes and rolling plans with the involvement of all stakeholders, e.g., relevant sectors, research organizations, communities, industry and donors.

In a nutshell, development of high-performing national health research systems in the countries of the WHO African Region, though optional, is an imperative. It may be the only way of breaking free from the current vicious cycle of ill-health and poverty.
The use of sleep aids among Emergency Medicine residents: a web based survey
Authors: Handel Daniel A , Raja Ali , Lindsell Christopher J
Published: October 2006

Background

Sleepiness is a significant problem among residents due to chronic sleep deprivation. Recent studies have highlighted medical errors due to resident sleep deprivation. We hypothesized residents routinely use pharmacologic sleep aids to manage their sleep deprivation and reduce sleepiness.

Methods

A web-based survey of US allopathic Emergency Medicine (EM) residents was conducted during September 2004. All EM residency program directors were asked to invite their residents to participate. E-mail with reminders was used to solicit participation. Direct questions about use of alcohol and medications to facilitate sleep, and questions requesting details of sleep aids were included.

Results

Of 3,971 EM residents, 602 (16%) replied to the survey. Respondents were 71% male, 78% white, and mean (SD) age was 30 (4) years, which is similar to the entire EM resident population reported by the ACGME. There were 32% 1st year, 32% 2nd year, 28% 3rd year, and 8% 4th year residents. The Epworth Sleepiness Scale (ESS) showed 38% of residents were excessively sleepy (ESS 11–16) and 7% were severely sleepy (ESS>16). 46% (95 CI 42%–50%) regularly used alcohol, antihistamines, sleep adjuncts, benzodiazepines, or muscle relaxants to help them fall or stay asleep. Study limitations include low response and self-report.

Conclusion

Even with a low response rate, sleep aid use among EM residents may be common. How this affects performance, well-being, and health remains unknown.
LitMiner: integration of library services within a bio-informatics application
Authors: Demaine Jeffrey , Martin Joel , Wei Lynn , de Bruijn Berry
Published: October 2006

Background

This paper examines how the adoption of a subject-specific library service has changed the way in which its users interact with a digital library. The LitMiner text-analysis application was developed to enable biologists to explore gene relationships in the published literature. The application features a suite of interfaces that enable users to search PubMed as well as local databases, to view document abstracts, to filter terms, to select gene name aliases, and to visualize the co-occurrences of genes in the literature. At each of these stages, LitMiner offers the functionality of a digital library. Documents that are accessible online are identified by an icon. Users can also order documents from their institution's library collection from within the application. In so doing, LitMiner aims to integrate digital library services into the research process of its users.

Methods

Case study

Results

This integration of digital library services into the research process of biologists results in increased access to the published literature.

Conclusion

In order to make better use of their collections, digital libraries should customize their services to suit the research needs of their patrons.