Showing papers by "Queen's University published in 2008"

Impacts of climate warming on terrestrial ectotherms across latitude.

Abstract: The impact of anthropogenic climate change on terrestrial organisms is often predicted to increase with latitude, in parallel with the rate of warming. Yet the biological impact of rising temperatures also depends on the physiological sensitivity of organisms to temperature change. We integrate empirical fitness curves describing the thermal tolerance of terrestrial insects from around the world with the projected geographic distribution of climate change for the next century to estimate the direct impact of warming on insect fitness across latitude. The results show that warming in the tropics, although relatively small in magnitude, is likely to have the most deleterious consequences because tropical insects are relatively sensitive to temperature change and are currently living very close to their optimal temperature. In contrast, species at higher latitudes have broader thermal tolerance and are living in climates that are currently cooler than their physiological optima, so that warming may even enhance their fitness. Available thermal tolerance data for several vertebrate taxa exhibit similar patterns, suggesting that these results are general for terrestrial ectotherms. Our analyses imply that, in the absence of ameliorating factors such as migration and adaptation, the greatest extinction risks from global warming may be in the tropics, where biological diversity is also greatest.

Nanomaterials and nanoparticles: Sources and toxicity

Abstract: This review is written with the goal of informing public health concerns related to nanoscience, while raising awareness of nanomaterials toxicity among scientists and manufacturers handling them. We show that humans have always been exposed to nanoparticles and dust from natural sources and human activities, the recent development of industry and combustion-based engine transportation profoundly increasing anthropogenic nanoparticulate pollution. The key to understanding the toxicity of nanoparticles is that their minute size, smaller than cells and cellular organelles, allows them to penetrate these basic biological structures, disrupting their normal function. Among diseases associated with nanoparticles are asthma, bronchitis, lung cancer, neurodegenerative diseases (such as Parkinson`s and Alzheimer`s diseases), Crohn`s disease, colon cancer. Nanoparticles that enter the circulatory system are related to occurrence of arteriosclerosis, and blood clots, arrhythmia, heart diseases, and ultimately cardiac death. We show that possible adverse effects of nanoparticles on human health depend on individual factors such as genetics and existing disease, as well as exposure, and nanoparticle chemistry, size, shape, and agglomeration state. The faster we will understand their causes and mechanisms, the more likely we are to find cures for diseases associated with nanoparticle exposure. We foresee a future with better-informed, and hopefully more cautious manipulation of engineered nanomaterials, as well as the development of laws and policies for safely managing all aspects of nanomaterial manufacturing, industrial and commercial use, and recycling.

A comparison of direct versus self-report measures for assessing physical activity in adults: a systematic review

Abstract: Accurate assessment is required to assess current and changing physical activity levels, and to evaluate the effectiveness of interventions designed to increase activity levels. This study systematically reviewed the literature to determine the extent of agreement between subjectively (self-report e.g. questionnaire, diary) and objectively (directly measured; e.g. accelerometry, doubly labeled water) assessed physical activity in adults. Eight electronic databases were searched to identify observational and experimental studies of adult populations. Searching identified 4,463 potential articles. Initial screening found that 293 examined the relationship between self-reported and directly measured physical activity and met the eligibility criteria. Data abstraction was completed for 187 articles, which described comparable data and/or comparisons, while 76 articles lacked comparable data or comparisons, and a further 30 did not meet the review's eligibility requirements. A risk of bias assessment was conducted for all articles from which data was abstracted. Correlations between self-report and direct measures were generally low-to-moderate and ranged from -0.71 to 0.96. No clear pattern emerged for the mean differences between self-report and direct measures of physical activity. Trends differed by measure of physical activity employed, level of physical activity measured, and the gender of participants. Results of the risk of bias assessment indicated that 38% of the studies had lower quality scores. The findings suggest that the measurement method may have a significant impact on the observed levels of physical activity. Self-report measures of physical activity were both higher and lower than directly measured levels of physical activity, which poses a problem for both reliance on self-report measures and for attempts to correct for self-report – direct measure differences. This review reveals the need for valid, accurate and reliable measures of physical activity in evaluating current and changing physical activity levels, physical activity interventions, and the relationships between physical activity and health outcomes.

British guideline on the management of asthma: A national clinical guideline

Abstract: These guidelines have been replaced by British Guideline on the Management of Asthma. A national clinical guideline. Superseded By 2012 Revision Of 2008 Guideline: British Guideline on the Management of Asthma. Thorax 2008 May; 63(Suppl 4): 1–121.

Genetic variation across species' geographical ranges: the central-marginal hypothesis and beyond

Abstract: There is growing interest in quantifying genetic population structure across the geographical ranges of species to understand why species might exhibit stable range limits and to assess the conservation value of peripheral populations. However, many assertions regarding peripheral populations rest on the long-standing but poorly tested supposition that peripheral populations exhibit low genetic diversity and greater genetic differentiation as a consequence of smaller effective population size and greater geographical isolation relative to geographically central populations. We reviewed 134 studies representing 115 species that tested for declines in within-population genetic diversity and/or increases in among-population differentiation towards range margins using nuclear molecular genetic markers. On average, 64.2% of studies detected the expected decline in diversity, 70.2% of those that tested for it showed increased differentiation and there was a positive association between these trends. In most cases, however, the difference in genetic diversity between central and peripheral population was not large. Although these results were consistent across plants and animals, strong taxonomic and biogeographical biases in the available studies call for a cautious generalization of these results. Despite the large number of studies testing these simple predictions, very few attempted to test possible mechanisms causing reduced peripheral diversity or increased differentiation. Almost no study incorporated a phylogeographical framework to evaluate historical influences on contemporary genetic patterns. Finally, there has been little effort to test whether these geographical trends in putatively neutral variation at marker loci are reflected by quantitative genetic trait variation, which is likely to influence the adaptive potential of populations across the geographical range.

Institutional Theory in the Study of Multinational Corporations: A Critique and New Directions

Abstract: This paper was motivated by the growing interest of scholars of multinational corporations (MNCs) in the institutional perspective. Our review of the literature suggests that international management applications of this perspective have been dominated by a narrow set of neoinstitutional ideas. We develop a set of provocations that challenge the validity of traditional neoinstitutionalism in the context of MNCs. We then offer ideas for more novel theory building in the study of MNCs, based on integrating “old” and “new” institutionalism.

Gene expression-based survival prediction in lung adenocarcinoma: a multi-site, blinded validation study.

Abstract: Although prognostic gene expression signatures for survival in early-stage lung cancer have been proposed, for clinical application, it is critical to establish their performance across different subject populations and in different laboratories. Here we report a large, training-testing, multi-site, blinded validation study to characterize the performance of several prognostic models based on gene expression for 442 lung adenocarcinomas. The hypotheses proposed examined whether microarray measurements of gene expression either alone or combined with basic clinical covariates (stage, age, sex) could be used to predict overall survival in lung cancer subjects. Several models examined produced risk scores that substantially correlated with actual subject outcome. Most methods performed better with clinical data, supporting the combined use of clinical and molecular information when building prognostic models for early-stage lung cancer. This study also provides the largest available set of microarray data with extensive pathological and clinical annotation for lung adenocarcinomas.

Investigation, treatment and monitoring of late-onset hypogonadism in males: ISA, ISSAM, EAU, EAA and ASA recommendations

Abstract: Demographic data clearly demonstrate that the percentage of the population in the older age group is increasing. Androgen deficiency in the aging male has become a topic of increasing interest and debate throughout the world. Cross-sectional and longitudinal data indicate that the testosterone falls progressively with age and that a significant percentage of men over the age of 60 years have serum testosterone levels that are below the lower limits of young adult (age 20–30 years) men (1–4). The principal questions raised by these observations are whether older hypogonadal men will benefit from testosterone treatment and what will be the risks associated with such intervention. The past decade has brought evidence of benefit of androgen treatment of hypogonadal men on multiple target organs and the recent studies show short-term beneficial effects of testosterone in older men that are similar to those in younger men. This has been comprehensively reviewed and summarized by the Institute of Medicine in ‘Testosterone and Aging: Clinical Research Directions’ (5). Long-term data on the effects of testosterone treatment in the older population are limited mainly to effects on body composition and bone mass (6–11). Key questions of the effects of testosterone on patient reported outcomes and functional benefits that may retard physical or mental frailty of the elderly or improve the quality of life are not yet available. Specific risk data on the prostate and cardiovascular systems are needed.

Breastfeeding and Child Cognitive Development: New Evidence From a Large Randomized Trial

Abstract: Context: The evidence that breastfeeding improves cognitive development is based almost entirely on observational studies and is thus prone to confounding by subtle behavioral differences in the breastfeeding mother’s behavior or her interaction with the infant. Objective: To assess whether prolonged and exclusive breastfeeding improves children’s cognitive ability at age 6.5 years.

Ferruginous Conditions Dominated Later Neoproterozoic Deep-Water Chemistry

Abstract: Earth9s surface chemical environment has evolved from an early anoxic condition to the oxic state we have today. Transitional between an earlier Proterozoic world with widespread deep-water anoxia and a Phanerozoic world with large oxygen-utilizing animals, the Neoproterozoic Era [1000 to 542 million years ago (Ma)] plays a key role in this history. The details of Neoproterozoic Earth surface oxygenation, however, remain unclear. We report that through much of the later Neoproterozoic (

Identification in rats of a programming window for reproductive tract masculinization, disruption of which leads to hypospadias and cryptorchidism

Abstract: Becoming a phenotypic male is ultimately determined by androgen-induced masculinization. Disorders of fetal masculinization, resulting in hypospadias or cryptorchidism, are common, but their cause remains unclear. Together with the adult-onset disorders low sperm count and testicular cancer, they can constitute a testicular dysgenesis syndrome (TDS). Although masculinization is well studied, no unifying concept explains normal male reproductive development and its abnormalities, including TDS. We exposed rat fetuses to either anti-androgens or androgens and showed that masculinization of all reproductive tract tissues was programmed by androgen action during a common fetal programming window. This preceded morphological differentiation, when androgen action was, surprisingly, unnecessary. Only within the programming window did blocking androgen action induce hypospadias and cryptorchidism and altered penile length in male rats, all of which correlated with anogenital distance (AGD). Androgen-driven masculinization of females was also confined to the same programming window. This work has identified in rats a common programming window in which androgen action is essential for normal reproductive tract masculinization and has highlighted that measuring AGD in neonatal humans could provide a noninvasive method to predict neonatal and adult reproductive disorders. Based on the timings in rats, we believe the programming window in humans is likely to be 8–14 weeks of gestation.

Chemotherapy in addition to supportive care improves survival in advanced non-small-cell lung cancer: A systematic review and meta-analysis of individual patient data from 16 randomized controlled trials

Abstract: PURPOSE Since our individual patient data (IPD) meta-analysis (MA) of supportive care and chemotherapy for non-small-cell lung cancer (NSCLC), published in 1995, many trials have been completed. An updated, IPD MA has been carried out to assess newer regimens and determine conclusively the effect of chemotherapy. METHODS Systematic searches for randomized controlled trials (RCTs) were undertaken, followed by central collection, checking, and reanalysis of updated IPD. Results from RCTs were combined to calculate individual and pooled hazard ratios (HRs). RESULTS Data were obtained from 2,714 patients from 16 RCTs. There were 1,293 deaths among 1,399 patients assigned supportive care and chemotherapy and 1,240 among 1,315 assigned supportive care alone. Results showed a significant benefit of chemotherapy (HR, 0.77; 95% CI, 0.71 to 0.83; P

The surprisingly diverse ways that prokaryotes move

Abstract: Prokaryotic cells move through liquids or over moist surfaces by swimming, swarming, gliding, twitching or floating. An impressive diversity of motility mechanisms has evolved in prokaryotes. Movement can involve surface appendages, such as flagella that spin, pili that pull and Mycoplasma 'legs' that walk. Internal structures, such as the cytoskeleton and gas vesicles, are involved in some types of motility, whereas the mechanisms of some other types of movement remain mysterious. Regardless of the type of motility machinery that is employed, most motile microorganisms use complex sensory systems to control their movements in response to stimuli, which allows them to migrate to optimal environments.

NICAD: Accurate Detection of Near-Miss Intentional Clones Using Flexible Pretty-Printing and Code Normalization

Abstract: This paper examines the effectiveness of a new language- specific parser-based but lightweight clone detection approach. Exploiting a novel application of a source transformation system, the method accurately finds near-miss clones using an efficient text line comparison technique. The transformation system assists the method in three ways. First, using agile parsing it provides user-specified flexible pretty- printing to remove noise, standardize formatting and break program statements into parts such that potential changes can be detected as simple linewise text differences. Second, it provides efficient flexible extraction of potential clones to be compared using island grammars and agile parsing to select granularities and enumerate potential clones. Third, using transformation rules it provides flexible code normalization to allow for local editing differences between similar code segments and filtering out of uninteresting parts of potential clones. In this paper we introduce the theory and practice of the framework and demonstrate its use in finding function clones in C code. Early experiments indicate that the method is capable of finding near-miss clones with high precision and recall, and with reasonable performance.

Productivity and the Decision to Import and Export: Theory and Evidence

Abstract: This paper develops an open economy model with heterogeneous final goods producers who simultaneously choose whether to export their goods and whether to use imported intermediates. The model highlights mechanisms whereby import policies affect aggregate productivity, resource allocation, and industry export activity along both the extensive and intensive margins. Using the theoretical model, we develop and estimate a structural empirical model that incorporates heterogeneity in productivity and shipping costs using Chilean plant-level data for a set of manufacturing industries. The estimated model is consistent with the key features of the data regarding productivity, exporting, and importing. We perform a variety of counterfactual experiments to assess quantitatively the positive and normative effects of barriers to trade in import and export markets. These experiments suggest that there are substantial aggregate productivity and welfare gains due to trade. Furthermore, because of import and export complementarities, policies which inhibit the importation of foreign intermediates can have a large adverse effect on the exportation of final goods.

Exploring the effects of trust, task interdependence and virtualness on knowledge sharing in teams

Abstract: The sharing of knowledge within teams is critical to team functioning. However, working with team members who are in different locations (i.e. in virtual teams) may introduce communication challenges and reduce opportunities for rich interactions, potentially affecting knowledge sharing and its outcomes. Therefore, using questionnaire-based data, this study examined the potential effects of dif- ferent aspects of virtuality on a knowledge-sharing model. Social exchange theory was used to develop a model relating trust to knowledge sharing and knowledge sharing to team effectiveness. The moderating effects of virtuality and task inter- dependence on these relationships were examined. A strong positive relationship was found between trust and knowledge sharing for all types of teams (local, hybrid and distributed), but the relationship was stronger when task interdepen- dence was low, supporting the position that trust is more critical in weak structural situations. Knowledge sharing was positively associated with team effectiveness outcomes; however, this relationship was moderated by team imbalance and hybrid structures, such that the relationship between sharing and effectiveness was weaker. Organizations should therefore avoid creating unbalanced or hybrid virtual teams.

Heuristic evaluation for games: usability principles for video game design

Abstract: Most video games require constant interaction, so game designers must pay careful attention to usability issues. However, there are few formal methods for evaluating the usability of game interfaces. In this paper, we introduce a new set of heuristics that can be used to carry out usability inspections of video games. The heuristics were developed to help identify usability problems in both early and functional game prototypes. We developed the heuristics by analyzing PC game reviews from a popular gaming website, and the review set covered 108 different games and included 18 from each of 6 major game genres. We analyzed the reviews and identified twelve common classes of usability problems seen in games. We developed ten usability heuristics based on the problem categories, and they describe how common game usability problems can be avoided. A preliminary evaluation of the heuristics suggests that they help identify game-specific usability problems that can easily be overlooked otherwise.

Double-blind review favours increased representation of female authors

Abstract: Double-blind peer review, in which neither author nor reviewer identity are revealed, is rarely practised in ecology or evolution journals However, in 2001, double-blind review was introduced by the journal Behavioral Ecology Following this policy change, there was a significant increase in female first-authored papers, a pattern not observed in a very similar journal that provides reviewers with author information No negative effects could be identified, suggesting that double-blind review should be considered by other journals

Hemispheric-scale patterns of climate-related shifts in planktonic diatoms from North American and European lakes

Abstract: A synthesis of over 200 diatom-based paleolimnological records from nonacidified/nonenriched lakes reveals remarkably similar taxon-specific shifts across the Northern Hemisphere since the 19th century. Our data indicate that these diatom shifts occurred in conjunction with changes in freshwater habitat structure and quality, which, in turn, we link to hemispheric warming trends. Significant increases in the relative abundances of planktonic Cyclotella taxa (P<0.01) were concurrent with sharp declines in both heavily silicified Aulacoseira taxa (P<0.01) and benthic Fragilaria taxa (P<0.01). We demonstrate that this trend is not limited to Arctic and alpine environments, but that lakes at temperate latitudes are now showing similar ecological changes. As expected, the onset of biological responses to warming occurred significantly earlier (P<0.05) in climatically sensitive Arctic regions (median age=ad 1870) compared with temperate regions (median age=ad 1970). In a detailed paleolimnological case study, we report strong relationships (P<0.005) between sedimentary diatom data from Whitefish Bay, Lake of the Woods (Ontario, Canada), and long-term changes in air temperature and ice-out records. Other potential environmental factors, such as atmospheric nitrogen deposition, could not explain our observations. These data provide clear evidence that unparalleled warming over the last few decades resulted in substantial increases in the length of the ice-free period that, similar to 19th century changes in high-latitude lakes, likely triggered a reorganization of diatom community composition. We show that many nonacidified, nutrient-poor, freshwater ecosystems throughout the Northern Hemisphere have crossed important climatically induced ecological thresholds. These findings are worrisome, as the ecological changes that we report at both mid- and high-latitude sites have occurred with increases in mean annual air temperature that are less than half of what is projected for these regions over the next half century.

Random-Forests-Based Network Intrusion Detection Systems

Abstract: Prevention of security breaches completely using the existing security technologies is unrealistic. As a result, intrusion detection is an important component in network security. However, many current intrusion detection systems (IDSs) are rule-based systems, which have limitations to detect novel intrusions. Moreover, encoding rules is time-consuming and highly depends on the knowledge of known intrusions. Therefore, we propose new systematic frameworks that apply a data mining algorithm called random forests in misuse, anomaly, and hybrid-network-based IDSs. In misuse detection, patterns of intrusions are built automatically by the random forests algorithm over training data. After that, intrusions are detected by matching network activities against the patterns. In anomaly detection, novel intrusions are detected by the outlier detection mechanism of the random forests algorithm. After building the patterns of network services by the random forests algorithm, outliers related to the patterns are determined by the outlier detection algorithm. The hybrid detection system improves the detection performance by combining the advantages of the misuse and anomaly detection. We evaluate our approaches over the knowledge discovery and data mining 1999 (KDDpsila99) dataset. The experimental results demonstrate that the performance provided by the proposed misuse approach is better than the best KDDpsila99 result; compared to other reported unsupervised anomaly detection approaches, our anomaly detection approach achieves higher detection rate when the false positive rate is low; and the presented hybrid system can improve the overall performance of the aforementioned IDSs.

Treatment of neuromyelitis optica with rituximab: retrospective analysis of 25 patients.

Abstract: Background: Neuromyelitis optica (NMO) is an uncommon, life-threatening inflammatory demyelinating disorder. Recently, much has become known about its immunopathogenesis. However, optimal treatments, with expected outcomes, have not been established. Objective: To evaluate the use and efficacy of rituximab for treating NMO. Design: Retrospective multicenter case series of NMO patients treated with rituximab. Setting: Seven tertiary medical centers in the United States and England. Patients: Twenty-five patients (including 2 children), 23 of whom experienced relapses despite use of other drugs before rituximab. Extended follow-up of 7 previously reported patients is included. Interventions: Infusions of rituximab at median intervals of 8 months. Main Outcome Measures: Annualized relapse rate and disability (expressed as Expanded Disability Status Scale score). Results: At a median follow-up of 19 months, the median annualized posttreatment relapse rate was lower than the pretreatment rate (0 [range 0-3.2] vs 1.7 [range, 0.5-5] relapses, P<.001). Disability improved or stabilized in 20 of 25 patients (80%, P=.02). Two patients died during the follow-up period, 1 owing to a brainstem relapse and 1 owing to suspected septicemia. Infections were reported in 20% of patients. Conclusions: In NMO, treatment with rituximab appears to reduce the frequency of attacks, with subsequent stabilization or improvement in disability.