bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Alcohol‐Preferring and Nonpreferring Selectively Bred Rat Lines. I. Ethanol Initiation and Limited Access Operant Self‐Administration
Authors: Samson Herman H. , Files Forrest J. , Denning Charles , Marvin Shelly
Published: February 2008

Several lines of alcohol‐preferring and alcohol‐nonpreferring rats have been developed using selective breeding based on 24‐hr homecage ethanol consumption. However, it remains unclear if the selection based on two‐bottle choice resulted in similar ethanol self‐administration when measured using an operant procedure. In this paper, we compare our previous work using alcohol‐accepting (AA) and alcohol‐nonaccepting (ANA) rats with data obtained using the identical procedures in the (P) and (NP) rat lines, and both replicate lines of the high alcohol drinking (HAD1 and HAD2) and low alcohol drinking (LAD1 and LAD2) lines. All rats from each line were initiated to self‐administer 10% ethanol using the sucrose fading procedure. After initiation, increasing concentrations of ethanol up to 30% ethanol were tested. The results indicated that only in the LAD1 and LAD2 lines was ethanol presentation not able to maintain lever pressing after initiation. Compared with the AA line, the P, HAD1, HAD2, and NP lines all self‐administered more ethanol in the operant paradigm after initiation. The ANA line self‐administered less ethanol than the AA line, but more than the LAD lines. Correlational analysis of homecage consumption with operant ethanol self‐administration suggested that ‐62% of the genetic variance in operant self‐administration resulted from genes selected for the homecage drinking. At the same time, it was clear that there were genetic influences on operant self‐administration that were not selected for by homecage ethanol drinking.
Comparison of Alcohol‐Preferring and Nonpreferring Selectively Bred Rat Lines. II. Operant Self‐Administration in a Continuous‐Access Situation
Authors: Files Forrest J. , Samson Herman H. , Denning Charles E. , Marvin Shelly
Published: February 2008

Several rat lines have been developed using preference/nonpreference and daily ethanol intake in the homecage as criteria for selective breeding. Using these lines, behavioral and neural factors that may underlie the genetic basis for the control of ethanol consumption have been examined. In this paper, we report data from eight of these selected lines: the Alcohol‐Preferring (P) and Alcohol‐Nonpreferring (NP), the Alcohol‐Accepting (AA) and Alcohol‐Nonaccepting (ANA), and the High Alcohol Drinking (HAD1 and HAD2) and Low Alcohol Drinking (LAD1 and LAD2) rats. All lines were tested using operant procedures and the same protocols for both the ethanol self‐administration initiation and measurement of continuous‐access ethanol consumption. During continuous access, the animals were housed in operant chambers with access to 10% (v/v) ethanol after responses on one lever, food pellets (45 mg) after responses on a second lever, and water in a drinking tube that was connected to a drinkometer circuit Under these procedures, both similarities and differences among the selected lines on continuous‐access operant ethanol intake were observed. For example, overall total homecage ethanol drinking was similar for the AA and both HAD lines. When examined in the operant continuous‐access situation, however, the AA rats displayed a different consumption pattern, compared with the HAD lines. Data suggest that the frequency of drinking bouts was a primary factor in the phenotypic homecage selection of the preferring lines that was revealed by the use of the continuous‐access operant procedure. In general, data suggest that genes related to ethanol preference and intake in homecage continuous‐access situations may not be identical to those related to ethanol's reinforcing function in operant continuous‐access conditions. Because ethanol consumption appears to be controlled by different drinking patterns across lines, the selected lines provide for a variety of models to understand how varying genotypes can impact ethanol consumption.
Effects of Naltrexone Administered Repeatedly Across 30 or 60 Days on Ethanol Consumption Using a Limited Access Procedure in the Rat
Authors: Stromberg Michael F. , Volpicelli Joseph R. , O'Brien Charles P.
Published: February 2008

The present study examined the effects of naltrexone, 1.0 mg/kg, administered repeatedly across both 30 and 60 days on the consumption of an unsweetened ethanol solution by outbred Wistar rats in a limited access procedure. Naltrexone significantly suppressed consumption of ethanol across both 30 and 60 days. These results provide no evidence for the development of tolerance based on such factors as receptor upregulation or supersensitivity due to the repeated administration of naltrexone across extended periods. Ethanol consumption during the final one‐third of the naltrexone sessions, for both the 30‐ and 60‐day groups, was significantly lower than during the initial sessions. These results suggest an associative component That is, the rats apparently learned that ethanol consumption was no longer reinforcing across repeated exposures. After termination of naltrexone treatment, consumption of ethanol immediately increased. However, consumption in those rats who were administered naltrexone for 60 days remained significantly suppressed, compared with consumption in those rats who were administered naltrexone for 30 days. These results suggest that naltrexone reduces ethanol consumption by blocking endogenous opioid receptors that mediate, at least in part, ethanol's reinforcing properties. In addition, these data suggest that longer clinical use of naltrexone, as a pharmacological adjunct to psychosocial treatment for alcohol‐dependent patients, may be beneficial in reducing the number of relapses experienced.
Platelet count is a sensitive predictor of autologous peripheral blood progenitor cell collection yield in previously treated plasma cell disease patients
Authors: Zubair Abba C. , Grant Rhonda , Wu Wenting , Tun Han , Rivera Candido , Moreno‐Aspitia Alvaro , Joyce Michael , Roy Vivek , Colon‐Otero Gerardo , Solberg Lawrence A.
Published: February 2008

BACKGROUND: It is often a clinical dilemma to determine when to collect autologous peripheral blood progenitor cells (PBPCs) in patients who received prior chemotherapy. It is also challenging to predict if the collected cells will be enough for one or two transplants.

STUDY DESIGN AND METHODS: A total of 103 PBPC donors were followed to evaluate factors that predict poor autologous PBPC collection. The donors were categorized into three groups: plasma cell disorders (PCDs), lymphomas, and normal allogeneic donors.

RESULTS: Our evaluation showed that platelet (PLT) count before growth factor administration significantly correlated with total CD34+ cell yield (Spearman r = 0.38, p < 0.001). Further analysis showed this correlation was only significant in plasma cell disease patients who received prior chemotherapy (Spearman r = 0.5, p = 0.008). Baseline PLT counts did not correlate with PBPC collection yield in untreated PCD, lymphoma, and normal allogeneic donors. In addition, daily PLT count during PBPC harvest correlated with CD34+ cell yield for that day (Spearman r = 0.41, p < 0.001). With a multiple linear regression model (adjusted R2 = 0.31, AIC = 63.1), it has been determined that the baseline PLT count significantly correlates with total CD34+ cell yield in treated PCD patients.

CONCLUSION: Baseline PLT count is a sensitive indicator of autologous PBPC mobilization in PCD patients who received prior chemotherapy. This finding may be considered before growth factor administration to determine the optimal period to mobilize treated PCD patients and to predict if enough cells can be collected for one or two transplants.
A Psychometric Study of Information Technology Risks in the Workplace
Authors: Coles Robert , Hodgkinson Gerard P.
Published: February 2008

As organizations become increasingly reliant on information technology (IT) they are exposed to a growing number of risks. Surprisingly, however, very few studies to date have investigated the psychometric representation of IT risks, and none have been undertaken in the workplace. Accordingly, the present study was designed to map the judgments of a representative group of workplace IT users. Fifty‐seven participants evaluated 18 IT risk scenarios by means of 13 bipolar attribute‐rating scales. Profile proximities derived from the raw data were submitted to a weighted multidimensional scaling analysis. The results indicated that a six‐dimensional solution was required on both statistical and conceptual grounds to represent adequately the participants' judgments. The dimensions reflected the extent to which the various risk scenarios were perceived as: (1) serious or minor in nature; (2) having a high or low probability of occurrence; (3) causing a high or low degree of stress; (4) deliberate or accidental; (5) having an impact on the organization or on individuals; and (6) the product of human or technological causes. The data were also submitted to a series of hierarchical cluster analyses, using a variety of agglomeration techniques. This second approach revealed a robust structure in which the risk scenarios were grouped into two broad categories, based on whether the events depicted would be likely to have a major or minor impact. The major impact category broke down further, into two subcategories, based on whether the scenarios were seen to arise from deliberate causes or through negligence. In conclusion, we consider the implications of our findings for future research, the refinement of IT risk assessment frameworks and tools, and the training of risk management professionals.
Contemporary Terrorism: Risk Perception in the London Options Market
Authors: Garvey John , Mullins Martin
Published: February 2008

Previous studies have a demonstrated a linkage between terrorist attacks and the operation of financial markets. This article focuses on terrorist events carried out over the last five years and examines how they have been perceived among participants on the London financial market. Data from the London options market suggest a high degree of sensitivity to these events. We argue that this sensitivity reveals a vulnerability in the financial markets should the recent trends in terrorist activity continue.
Application of Correspondence Analysis in the Assessment of Mine Tailings Dam Breakage Risk in the Mediterranean Region
Authors: Salgueiro Ana Rita , Pereira Henrique Garcia , Rico Maria‐Teresa , Benito Gerado , Díez‐Herreo Andrés
Published: February 2008

A new statistical approach for preliminary risk evaluation of breakage in tailings dam is presented and illustrated by a case study regarding the Mediterranean region. The objective of the proposed method is to establish an empirical scale of risk, from which guidelines for prioritizing the collection of further specific information can be derived. The method relies on a historical database containing, in essence, two sets of qualitative data: the first set concerns the variables that are observable before the disaster (e.g., type and size of the dam, its location, and state of activity), and the second refers to the consequences of the disaster (e.g., failure type, sludge characteristics, fatalities categorization, and downstream range of damage). Based on a modified form of correspondence analysis, where the second set of attributes are projected as “supplementary variables” onto the axes provided by the eigenvalue decomposition of the matrix referring to the first set, a “qualitative regression” is performed, relating the variables to be predicted (contained in the second set) with the “predictors” (the observable variables). On the grounds of the previously derived relationship, the risk of breakage in a new case can be evaluated, given observable variables. The method was applied in a case study regarding a set of 13 test sites where the ranking of risk obtained was validated by expert knowledge. Once validated, the procedure was included in the final output of the e‐EcoRisk UE project (A Regional Enterprise Network Decision‐Support System for Environmental Risk and Disaster Management of Large‐Scale Industrial Spills), allowing for a dynamic historical database updating and providing a prompt rough risk evaluation for a new case. The aim of this section of the global project is to provide a quantified context where failure cases occurred in the past for supporting analogue reasoning in preventing similar situations.
Work‐Related Road Safety: An Analysis Based on U.K. Bus Driver Performance
Authors: Dorn Lisa , Af Wåhlberg Anders
Published: February 2008

The effects of age and experience on accident involvement for bus drivers were investigated, with special emphasis upon the first years of being an operator, using two methods. First, direct calculations between these variables were undertaken. Thereafter, a variant of the method of quasi‐induced exposure (a ratio of culpable versus nonculpable accidents in the population) was used and referred to as the indirect method. These methods yielded fairly similar results, given that the samples used were drawn from the same population but only partly overlapping. It was found that experience had the strongest effect on accidents in the first year of driving, while age had a u‐shaped association with accidents, that is, young and old drivers had more accidents, something that was more apparent when experience was held constant. These results show that, for bus drivers, experience is initially more important than age, but after two or three years, the effect is small. Thereafter, age is the more discernible variable, although it is a very weak factor in predicting crash risk.
A Risk‐Benefit Analysis of French High Fish Consumption: A QALY Approach
Authors: Guevel Marie‐Renée , Sirot Véronique , Volatier Jean‐Luc , Leblanc Jean‐Charles
Published: February 2008

The health risk and the nutritional benefit of a food are usually assessed separately. Toxicologists recommend limiting the consumption of certain fish because of methylmercury; while nutritionists recommend eating more oily fish because of omega 3. A common evaluation is imperative to provide coherent recommendations. In order to evaluate the risks along with the benefits related to fish consumption, a common metric based on the quality‐adjusted life year (QALY) method has been used. The impact of a theoretical change from a medium n‐3 PUFAs intake to a high intake is studied, in terms of the cardiovascular system (CHD mortality, stroke mortality and morbidity) and on fetal neuronal development (IQ loss or gain). This application can be considered as a sensitive analysis of the model used and looks at the impact of changing the dose‐response relationships between cardiovascular diseases and n‐3 PUFAs intakes. Results show that increasing fish consumption may have a beneficial impact on health. However, the confidence interval of the overall estimation has a negative lower bound, which means that this increase in fish consumption may have a negative impact due to MeHg contamination. Some limits of the QALY approach are identified. The first concerns determination of the dose‐response relationships. The second concerns the economic origins of the approach and of individual preferences. Finally, since only one beneficial aspect and one risk element were studied, consideration should be given to how other beneficial and risk components may be integrated in the model.
A Fuzzy Decision Tree for Fault Classification
Authors: Zio Enrico , Baraldi Piero , Popescu Irina C.
Published: February 2008

In plant accident management, the control room operators are required to identify the causes of the accident, based on the different patterns of evolution of the monitored process variables thereby developing. This task is often quite challenging, given the large number of process parameters monitored and the intense emotional states under which it is performed. To aid the operators, various techniques of fault classification have been engineered. An important requirement for their practical application is the physical interpretability of the relationships among the process variables underpinning the fault classification. In this view, the present work propounds a fuzzy approach to fault classification, which relies on fuzzy if‐then rules inferred from the clustering of available preclassified signal data, which are then organized in a logical and transparent decision tree structure. The advantages offered by the proposed approach are precisely that a transparent fault classification model is mined out of the signal data and that the underlying physical relationships among the process variables are easily interpretable as linguistic if‐then rules that can be explicitly visualized in the decision tree structure. The approach is applied to a case study regarding the classification of simulated faults in the feedwater system of a boiling water reactor.
Combining Measures of Risk Perceptions and Risk Activities: The Development of the RAPRA and PRISC Indices
Authors: Abbott‐Chapman Joan , Denholm Carey , Wyld Colin
Published: February 2008

The influence of risk perceptions on risk activities of teenagers is well known, but the development of indices, which combine measures of perception as well as behavioral outcomes, has proved problematical. This article discusses the ways in which this methodological problem was tackled within a five‐year, multiphase, multimethod study of factors affecting adolescent risk‐taking in Tasmania, Australia, which included an intergenerational comparison of adolescents and parents. The development of the Risk Activity by Personal Risk Assessment (RAPRA) Index combines measures of perceived riskiness of 26 activities identified by young people as involving varying degrees of risk, with the degree of participation by each respondent, through a rectangular model of weights. The Personal Risk Score Category (PRISC) Index summarizes and categorizes an individual's risk‐taking profile relative to the group's risk values and risk hierarchy established by the RAPRA Index. The article discusses ways in which technical problems involved in combining measures of risk perceptions and risk activities were addressed during index construction, compared with examples in the literature. Some key findings from analysis of two student and parent samples are presented as exemplars of the methods used and the results produced. Findings demonstrate the widespread nature of risk‐taking among teenagers, and the similarity of levels of risk‐taking between teenager and parental generations. The indices allow for detailed comparison of particular risk‐taking activities and reveal differences among teenagers now compared with parents when they were teenagers, and illustrate the dynamic cultural context of risk‐taking perceptions and values.
Marine and Offshore Safety Assessment by Incorporative Risk Modeling in a Fuzzy‐Bayesian Network of an Induced Mass Assignment Paradigm
Authors: Eleye‐Datubo A. G. , Wall A. , Wang J.
Published: February 2008

The incorporation of the human element into a probabilistic risk‐based model is one that requires a possibilistic integration of appropriate techniques and/or that of vital inputs of linguistic nature. While fuzzy logic is an excellent tool for such integration, it tends not to cross its boundaries of possibility theory, except via an evidential reasoning supposition. Therefore, a fuzzy‐Bayesian network (FBN) is proposed to enable a bridge to be made into a probabilistic setting of the domain. This bridge is formalized by way of the mass assignment theory. A framework is also proposed for its use in maritime safety assessment. Its implementation has been demonstrated in a maritime human performance case study that utilizes performance‐shaping factors as the input variables of this groundbreaking FBN risk model.
Comparative Risk Analysis of Dioxins in Fish and Fine Particles from Heavy‐Duty Vehicles
Authors: Leino Olli , Tainio Marko , Tuomisto Jouni T.
Published: February 2008

Dioxins and airborne fine particles are both environmental health problems that have been the subject of active public debate. Knowledge on fine particles has increased substantially during the last 10 years, and even the current, lowered levels in the Europe and in the United States appear to be a major public health problem. On the other hand, dioxins are ubiquitous persistent contaminants, some being carcinogens at high doses, and therefore of great concern. Our aim was to (a) quantitatively analyze the two pollutant health risks and (b) study the changes in risk in view of the current and forthcoming EU legislations on pollutants. We performed a comparative risk assessment for both pollutants in the Helsinki metropolitan area (Finland) and estimated the health effects with several scenarios. For primary fine particles: a comparison between the present emission situation for heavy‐duty vehicles and the new fine particle emission standards set by the EU. For dioxins: an EU directive that regulates commercial fishing of Baltic salmon and herring that exceed the dioxin concentration limit set for fish meat, and a derogation (= exemption) from the directive for these two species. Both of these two decisions are very topical issues and this study estimates the expected changes in health effects due to these regulations. It was found that the estimated fine particle risk clearly outweighed the estimated dioxin risk. A substantial improvement to public health could be achieved by initiating reductions in emission standards; about 30 avoided premature deaths annually in the study area. In addition, the benefits of fish consumption due to omega‐3 exposure were notably higher than the potential dioxin cancer risk. Both regulations were instigated as ways of promoting public health.
Trust and Risk Communication in High‐Risk Organizations: A Test of Principles from Social Risk Research
Authors: Conchie Stacey M. , Burns Calvin
Published: February 2008

This study explored the effects of open communication about occupational risks on workers' trust beliefs and trust intentions toward risk management, and the resilience of these beliefs and intentions to further risk information. An experimental survey of 393 student nurses showed the importance of open communication in the development of worker trust in risk management. Consistent with the trust asymmetry principle, we found that the increase in trust beliefs following open communication was weaker than the reduction in trust following a lack of communication. Further, the level of trust developed through communication (or lack of) influenced the way that subsequent risk information was processed. Negative risk information reduced trust beliefs in nurses with already low levels of trust while positive risk information increased trust beliefs only in those with already high levels. A similar pattern of results emerged for nurses' trust intentions, although the magnitude of these effects was weaker. The implications of these findings for occupational risk management are discussed.
Aggregating Disparate Epidemiological Evidence: Comparing Two Seminal EMF Reviews
Authors: O'Carroll Michael J. , Henshaw Denis L.
Published: February 2008

Two seminal reviews (IARC, 2002; CDHS, 2002) of possible health effects from power‐frequency EMFs reached partly different conclusions from similar epidemiological evidence. These differences have an impact on precautionary policy. We examine the statistical aggregation of results from individual disparate studies. Without consistent exposure metrics, the advantage of meta‐analysis to estimate magnitude of effect is lost. However, counting positive and statistically significant results yields important information. This is not a substitute for meta‐analysis, but a fall‐back when meaningful meta‐analysis is not available. Representative results from 33 independent adult leukemia studies tabled by IARC yielded 23.5 positives (p≈ 0.01) and 9 significant‐positives (p < 10−7). From 43 representative results from CDHS, there were 32 positive (p < 0.001) and 14 significant‐positives (p < 10−12). There were no significant‐negative results in either list. Results for adult brain cancer gave a similar, but less clear, message. Childhood leukemia EMF studies have been sufficiently comparable to allow selective pooled analysis, which was important in classifying carcinogenicity. Aggregating all the studies suggests that results for childhood leukemia are not stronger, numerically, than those for adult leukemia. CDHS did not note the number of significant‐positives, but noted the meta‐analytic summary and the number of positives, forming a view about the strength of these findings. IARC shows no evidence of considering the aggregation of results other than subjectively. It considered individual studies but this led to a tendency to fragment and dismiss evidence that is intrinsically highly significant. We make recommendations for future reviews.
Personal Efficacy, the Information Environment, and Attitudes Toward Global Warming and Climate Change in the United States
Authors: Kellstedt Paul M. , Zahran Sammy , Vedlitz Arnold
Published: February 2008

Despite the growing scientific consensus about the risks of global warming and climate change, the mass media frequently portray the subject as one of great scientific controversy and debate. And yet previous studies of the mass public's subjective assessments of the risks of global warming and climate change have not sufficiently examined public informedness, public confidence in climate scientists, and the role of personal efficacy in affecting global warming outcomes. By examining the results of a survey on an original and representative sample of Americans, we find that these three forces—informedness, confidence in scientists, and personal efficacy—are related in interesting and unexpected ways, and exert significant influence on risk assessments of global warming and climate change. In particular, more informed respondents both feel less personally responsible for global warming, and also show less concern for global warming. We also find that confidence in scientists has unexpected effects: respondents with high confidence in scientists feel less responsible for global warming, and also show less concern for global warming. These results have substantial implications for the interaction between scientists and the public in general, and for the public discussion of global warming and climate change in particular.
Food Safety in the Domestic Environment: The Effect of Consumer Risk Information on Human Disease Risks
Authors: Nauta Maarten J. , Fischer Arnout R. H. , Van Asselt Esther D. , De Jong Aarieke E. I. , Frewer Lynn J. , De Jonge Rob
Published: February 2008

The improvement of food safety in the domestic environment requires a transdisciplinary approach, involving interaction between both the social and natural sciences. This approach is applied in a study on risks associated withCampylobacteron broiler meat. First, some web‐based information interventions were designed and tested on participant motivation and intentions to cook more safely. Based on these self‐reported measures, the intervention supported by the emotion “disgust” was selected as the most promising information intervention. Its effect on microbial cross‐contamination was tested by recruiting a set of participants who prepared a salad with chicken breast fillet carrying a known amount of tracer bacteria. The amount of tracer that could be recovered from the salad revealed the transfer and survival ofCampylobacterand was used as a measure of hygiene. This was introduced into an existing risk model onCampylobacterin the Netherlands to assess the effect of the information intervention both at the level of exposure and the level of human disease risk. We showed that the information intervention supported by the emotion “disgust” alone had no measurable effect on the health risk. However, when a behavioral cue was embedded within the instruction for the salad preparation, the risk decreased sharply. It is shown that a transdisciplinary approach, involving research on risk perception, microbiology, and risk assessment, is successful in evaluating the efficacy of an information intervention in terms of human health risks. The approach offers a novel tool for science‐based risk management in the area of food safety.
Perceptions of Ecological Risk Associated with Mountain Pine Beetle (Dendroctonus ponderosae) Infestations in Banff and Kootenay National Parks of Canada
Authors: McFarlane Bonita L. , Witson David O. T.
Published: February 2008

Western Canada is experiencing an unprecedented outbreak of the mountain pine beetle (MPB). The MPB has the potential to impact some of Canada's national parks by affecting park ecosystems and the visitor experience. Controls have been initiated in some parks to lessen the impacts and to prevent the beetle from spreading beyond park boundaries. We examine the perception of ecological risk associated with MPB in two of Canada's national parks, the factors affecting perceptions of risk, and the influence of risk judgments on support for controlling MPB outbreaks in national parks. Data were collected using two studies of park visitors: a mail survey in 2003 and an onsite survey in 2005. The MPB was rated as posing a greater risk to the health and productivity of park ecosystems than anthropogenic hazards and other natural disturbance agents. Visitors who were familiar with MPB rated the ecological and visitor experience impacts as negative, unacceptable, and eliciting negative emotion. Knowledge and residency were the most consistent predictors of risk judgments. Of knowledge, risk, and demographic variables, only sex and risk to ecosystem domains influenced support for controlling the MPB in national parks. Implications for managing MPB in national parks, visitor education, and ecological integrity are discussed.
God's Country?
Authors: Russell Mead Walter
Published: February 2008

Abstract:  Religion has always been a major force in U.S. politics, but the recent surge in the number and the power of evangelicals is recasting the country's political scene—with dramatic implications for foreign policy. This should not be cause for panic: evangelicals are passionately devoted to justice and improving the world, and eager to reach out across sectarian lines.
Evangelicalism
Authors: Bloesch Donald G.
Published: February 2008

Abstract:  The evangelical ethos gives priority to grace over works and is shaped by its irrepressible missionary impulse; faith is existential rather than merely conceptual. The early roots of evangelicalism through the modern period are discussed, and put in context with other movements that grew out of the Reformation. The goal of Christian evangelizing is the creation of a person whose life bears witness to the authenticity of faith.
Examining Problems and Assumptions: An Update on Criticisms of Open Theism
Authors: Woodruff David M.
Published: February 2008

Abstract:  Open theism, a form of relational theology, has generated a host of criticisms. I examine some of the recent criticisms by analyzing several that center around biblical, doctrinal and philosophical problems. I show how many criticisms miss the mark by failing to recognize and address the underlying assumptions held by open theists.
Electrothermal Model Evaluation of Grain Size and Disorder Effects on Pulsed Voltage Response of Microstructured ZnO Varistors
Authors: Zhao Guogang , Joshi Ravi P. , Hjalmarson Harold P.
Published: February 2008

Time‐dependent, two‐dimensional, electrothermal simulations based on random Voronoi networks have been developed to study the internal heating, current distributions and breakdown effects in ZnO varistors in response to high‐voltage pulsing. The simulations allow for dynamic predictions of internal failures and to track the progression of hot‐spots and thermal stresses. The focus is on internal grain‐size variations and relative disorder including micropores. Our results predict that parameters such as the hold‐off voltage, internal temperature, and average dissipated energy density would be higher with more uniform grains. This uniformity is also predicted to produce lower thermal stresses and to allow for the application of longer duration pulses. It is shown that the principal failure mechanism arises from internal localized melting, while thermal stresses are well below the thresholds for cracking. Finally, detrimental effects of micropores have been quantified and shown to be in agreement with experimental trends.
In Situ Synthesis of Ultrafine ZrB2–SiC Composite Powders and the Pressureless Sintering Behaviors
Authors: Yan Yongjie , Zhang Hui , Huang Zhengren , Liu Jianxue , Jiang Dongliang
Published: February 2008

Ultrafine ZrB2–SiC composite powders have been synthesized in situ using carbothermal reduction reactions via the sol–gel method at 1500°C for 1 h. The powders synthesized had a relatively smaller average crystallite size (<200 nm), a larger specific surface area (∼20 m2/g), and a lower oxygen content (∼1.0 wt %). Composites of ZrB2+20 wt% SiC were pressureless sintered to ∼96.6% theoretical density at 2250°C for 2 h under an argon atmosphere using B4C and Mo as sintering aids. Vickers hardness and flexural strength of the sintered ceramic composites were 13.9±0.3 GPa and 294±14 MPa, respectively. The microstructure of the composites revealed that elongated SiC grain dispersed uniformly in the ZrB2 matrix. Oxidation from 1100° to 1600°C for 30 min showed no decrease in strength below 1400°C but considerable decrease in strength with a rapid weight increment was observed above 1500°C. The formation of a protective borosilicate glassy coating appeared at 1400°C and was gradually destroyed in the form of bubble at higher temperatures.
End of the Induction Period in Ordinary Portland Cement as Examined by High‐Resolution Scanning Electron Microscopy
Authors: Makar Jon M. , Chan Gordon W.
Published: February 2008

The early stages of ordinary Portland cement (OPC) hydration were studied by cold field emission scanning electron microscopy and isothermal conduction calorimetry. Particular attention was paid to samples from the end of the induction period, where an additional peak in the tricalcium silicate hydration reaction has recently been discovered. Higher resolution images were obtained than is possible with currentin situimaging techniques, allowing for the observation of features on the 5‐nm scale. The peak in the hydration at the end of the induction period was associated with both the formation of pores in the surface of the cement grains and the formation of nanoscale calcium silicate hydrate (C–S–H) structures on those surfaces. The effects of grinding of OPC and additions of tricalcium aluminate and tetracalcium aluminoferrite on the peak at the end of the induction period were also examined. The results of the study were compared with the models in the literature used to describe the causes of the induction period and its end.
Friction Behavior of Dental Porcelain with Different Leucite Particle Sizes
Authors: Zhang Yi , Xu Dengxiang , Rao Pinggen , Lü Ming , Wu Jianqing
Published: February 2008

The effect of leucite particle size on the friction behavior of dental ceramics was investigated using a ball‐on‐disc tribometer. The experimental loads were 20, 30 and 40 N and the tests were conducted unlubricated and under the lubrication of an artificial‐saliva. Dental ceramics with different leucite particle sizes, i.e. 0.5±0.2, 1.2±0.3 and 5±2 μm, were prepared by sintering the mixture of a low temperature frit and leucite powders with different average particle sizes (0.4, 1 and 5 μm). The results showed that the leucite particle size, experimental load and lubrication media had not significant effects on the steady‐state friction coefficient of the samples. However, the evolution of the friction coefficient was different, which could be generally classified into two categories, i.e. with and without an abrupt increase in the friction curve. The changes in experimental condition and leucite particle size were attributed to such difference.
Influences of Sintering Temperature on Piezoelectric, Dielectric and Ferroelectric Properties of Li/Ta‐Codoped Lead‐Free (Na,K)NbO3 Ceramics
Authors: Zhao Pei , Zhang Bo‐Ping , Li Jing‐Feng
Published: February 2008

Li/Ta‐codoped lead‐free (Na,K)NbO3 ceramics with a nominal composition of [(Na0.535K0.480)0.942Li0.058](Nb0.90Ta0.10)O3 were synthesized normally at 1070°–1100°C. The XRD patterns of all samples show a single pervoskite structure with tetragonal symmetry. Although MPB separating the orthorhombic and tetragonal symmetries was absent, the maximum piezoelectric coefficient (d33), electromechanical coupling coefficient (kp), Curie temperature (Tc), and remanent polarization (Pr) were optimized as 216 pC/N, 38.1%, 445°C, and 8.73 μC/cm2, respectively.
Solubility Limits of La and Y in Aluminum Oxynitride at 1870°C
Authors: Miller Lior , Kaplan Wayne D.
Published: February 2008

The solubility limits of important dopants (La and Y) in aluminum oxynitride (AlON) were measured using wavelength‐dispersive spectroscopy (WDS) mounted on a scanning electron microscope, from samples quickly cooled from 1870°C. To provide saturated AlON, samples were prepared with dopant concentrations well above the solubility limit, which was confirmed by the appearance of secondary phases using X‐ray diffraction, backscattered electron micrographs, and WDS. Measurements were conducted on polished samples without thermal or chemical etching. The results indicate solubility limits of 498±82 and 1775±128 ppm for La and Y in AlON at 1870°C, respectively. The solubility limit of Mg in AlON at 1870°C was found to be >4000 ppm. The relation between solubility limit and cation size is briefly discussed.
Odor‐based recognition of nectar in cursorial spiders
Authors: Patt Joseph M. , Pfannenstiel Robert S.
Published: February 2008

Carnivorous arthropods are known to rely on non‐prey foods, such as honeydew, pollen, and nectar. Consumption of plant‐based nutrients by spiders also appears to be widespread, especially in cursorial species. This is not surprising, as studies have shown that these spiders’ activity levels, survivorship, and reproduction are increased when their diet includes plant‐based nutrients, especially under conditions of prey scarcity. However, the sensory and behavioral means by which they recognize and locate non‐prey food is unknown. Here we show that immatures of a nectarivorous spider [Hibana futilis Banks (Araneae: Anyphaenidae)] can recognize and remember particular chemical stimuli associated with nectar. Following ingestion of minute amounts of sugar, these spiders exhibited counterturning and other local searching behaviors that increased their chances of finding more nectar. When placed on test arenas, spiders that were naïve with respect to nectar aroma located artificial nectaries composed of diluted honey significantly faster than unscented nectaries composed of 1 m sucrose solution. These results indicate that H. futilis is neurophysiologically and behaviorally adapted for recognizing olfactory stimuli. Interestingly, only spiders that ingested sugar and were engaged in local search responded to nectar aroma, suggesting that stimulation into local search is necessary to prime olfactory responses. We found that H. futilis could be conditioned to associate the presence of nectar with a novel aroma, in this case vanilla, and remember this aroma over the course of several hours. In arenas with vanilla‐scented nectaries, spiders that had previous experience feeding on vanilla‐scented sucrose droplets located the nectaries significantly faster than did vanilla‐naïve spiders. The capacity to remember specific aromas could enhance the spiders’ ability to find nectar, either when moving between different parts of the same plant or among different plant species. The results here indicate that nectarivorous spiders possess the sensory capabilities and programed behaviors necessary for efficient detection, recognition, and location of nectar sources.
Effect of photoperiod experienced by parents on diapause induction in Trichogramma cacoeciae
Authors: Pizzol Jeannine , Pintureau Bernard
Published: February 2008

In the genus Trichogramma, the prepupal stage can survive the cold season in diapause. However, optimal conditions for the induction of this cessation of development during the process of mass production of the parasitoid in a biological control program depend on the species. In Trichogramma cacoeciae Marchal (Hymenoptera: Trichogrammatidae), diapause is induced more easily if the parents are reared under short‐day conditions (L10:D14), and if the temperature is 10 °C rather than 13 °C. However, the effect of parental photoperiod on diapause induction is weaker at lower temperatures (10 °C). Following diapause induction, individuals can be stored at 3 °C for several months, up to 1 year. Non‐optimal conditions led to the establishment of a quiescent state in some or all individuals. In such cases, it was necessary to reduce the storage period to 1 or 2 months only, to prevent high mortality rates and low fecundity.
Chondroitin sulphate decreases collagen synthesis in normal and scleroderma fibroblasts through a Smad‐independent TGF‐β pathway – implication of C‐Krox and Sp1
Authors: Renard Emmanuelle , Chadjichristos Christos , Kypriotou Magdalini , Beauchef Gallic , Bordat Pascal , Dompmartin Anne , Widom Russell L. , Boumediene Karim , Pujol Jean‐Pierre , Galéra Philippe
Published: February 2008

Despite several investigations, the transcriptional mechanisms which regulate the expression of both type I collagen genes (COL1A1 and COL1A2) in either physiological or pathological situations, such as scleroderma, are not completely known. In this study, we determined the effects of both native ichtyan chondroïtin sulphate (CS) and its derived hydrolytic fragments (CSf) on human normal (NF) and scleroderma (SF) fibroblasts. Here, we demonstrate for the first time that CS and CSf exert an inhibitory effect on type I collagen protein synthesis and decrease the corresponding mRNA steady‐state levels of COL1A1 and COL1A2 in NF and SF. These glycosaminoglycan molecules repress COL1A1 gene transcription through a ‐112/‐61 bp sequence upstream the start site of transcription and imply hc‐Krox and Sp1 transcription factors. In addition, CS and CSf induced a down‐regulation of TβRI expression. As a conclusion, our findings highlight a possible new role for CS and CSf as anti‐fibrotic molecules and could help in elucidating the mechanisms of action by which CS and CSf exert their inhibitory effect on type I collagen synthesis.
Adipose stem cells for intervertebral disc regeneration: current status and concepts for the future
Authors: Hoogendoorn R. J. W. , Lu Z. F. , Kroeze R. J. , Bank R. A. , Wuisman P. I. , Helder M. N.
Published: February 2008

Introduction

Degenerative disc disease and emerging biological treatment approaches

Stem cell sources

Integration of ASC‐based regenerative medicine and surgery

In vitro studies

In vivo studies

Perspective

Conclusions

New regenerative treatment strategies are being developed for intervertebral disc degeneration of which the implantation of various cell types is promising. All cell types used so far require in vitro expansion prior to clinical use, as these cells are only limited available. Adipose‐tissue is an abundant, expendable and easily accessible source of mesenchymal stem cells. The use of these cells therefore eliminates the need for in vitro expansion and subsequently one‐step regenerative treatment strategies can be developed. Our group envisioned, described and evaluated such a one‐step procedure for spinal fusion in the goat model. In this review, we summarize the current status of cell‐based treatments for intervertebral disc degeneration and identify the additional research needed before adipose‐derived mesenchymal stem cells can be evaluated in a one‐step procedure for regenerative treatment of the intervertebral disc. We address the selection of stem cells from the stromal vascular fraction, the specific triggers needed for cell differentiation and potential suitable scaffolds. Although many factors need to be studied in more detail, potential application of a one‐step procedure for intervertebral disc regeneration seems realistic.
Caspases as therapeutic targets
Authors: Howley B. , Fearnhead H.O.
Published: February 2008

Introduction

Activation of caspases

Small molecule inhibitors of caspase activity and activation

Role of caspases in disease

Challenges facing the development of caspase therapeutics

Role of caspases in other aspects of cell death

Role of caspases in non‐apoptotic and non‐inflammatory processes

The future of caspase therapeutics

The development of small molecules to modulate caspase activity offers a novel therapeutic strategy in the treatment of apoptosis‐related and inflammatory diseases. Caspases are key mediators of apoptosis and inflammation; deregulation of their activation or expression can lead to the development of conditions such as neurodegenerative and autoinflammatory disorders. This review details the different caspase‐associated disorders while focusing on caspase‐1 inhibition as a potential therapeutic strategy. Problems facing the development of effective and safe caspase therapeutics will also be addressed.
Effect of a long‐term treatment with a low‐dose granulocyte colony‐stimulating factor on post‐infarction process in the heart
Authors: Okada Hideshi , Takemura Genzou , Li Yiwen , Ohno Takamasa , Li Longhu , Maruyama Rumi , Esaki Masayasu , Miyata Shusaku , Kanamori Hiromitsu , Ogino Atsushi , Nakagawa Munehiro , Minatoguchi Shinya , Fujiwara Takako , Fujiwara Hisayoshi
Published: February 2008

Although beneficial effects of granulocyte colony‐stimulating factor (G‐CSF) have been demonstrated on post‐myocardia infarction (MI) process, the mechanisms and feasibility are not fully agreed yet. We investigated effects of a long‐term treatment with a low‐dose G‐CSF started 1 day after the onset of MI, on post‐infarction process. One day after being made MI by left coronary ligation, mice were given G‐CSF (10 μg/kg/day) for 4 weeks. The G‐CSF treatment resulted in a significant mitigation of cardiac remodelling and dysfunction. In the G‐CSF‐treated hearts, the infarcted scar was smaller with less fibrosis and abundant vessels while in the non‐infarcted area, hypertrophic cardiomyocytes with attenuated degenerative changes and reduced fibrosis were apparent. These effects were accompanied by activation of signal transducer and activator of transcription 3 (STAT3) and Akt and also by up‐regulation of GATA‐4, myosin heavy chain and matrix metalloproteinases‐2 and ‐9. Apoptosis of cardiomyocytes appeared insignificant at any stages. Parthenolide, a STAT3 inhibitor, completely abolished the beneficial effects of G‐CSF on cardiac function and remodelling with loss of effect on both anti‐cardiomyocyte degeneration and anti‐fibrosis. In contrast, wortmannin, an Akt inhibitor, did not affect G‐CSF‐induced benefis despite cancelling vessel increase. In conclusion, treatment with G‐CSF at a small dose but for a long duration beneficially affects the post‐infarction process possibly through STAT3‐mediated anti‐cardiomyocyte degeneration and anti‐fibrosis, but not through anti‐cardiomyocyte apoptosis or Akt‐mediated angio‐genesis. The findings may also imply a more feasible way of G‐CSF administration in the clinical settings.