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Selected AbstractsLeft Ventricular Non Compaction in ChildrenCONGENITAL HEART DISEASE, Issue 5 2010Sara H. Weisz MD ABSTRACT Left ventricular non compaction (LVNC) is a myocardial disease characterized by a hypertrabeculated myocardium. The hypertrabeculations in the left ventricular wall define deep recesses communicating with the left ventricular chamber where blood penetrates with increased risk of blood clots in the meshwork of the prominent trabeculations. The left ventricular apex and the free wall are particularly affected. During in utero ventriculogenesis, myocardial blood supply is initially linked to the presence of sinusoids, in which blood penetrates and diffuses nutriments and oxygen to myocardial cells. Progressively, with the development of the heart and the increase of cells demand of blood, coronary arteries system develops. This step is associated with myocardial modification that leads to compaction of hypertrabeculated myocardial net. Probably, the premature interruption of this process leads to ventricular noncompaction. Many studies have been conducted in adults with hypertrabeculated myocardium. To date, data regarding childhood LVNC are sparse. The aim of this review is to summarize the clinical and preclinical knowledge about LVNC in children. [source] The Potential for Species Conservation in Tropical Secondary ForestsCONSERVATION BIOLOGY, Issue 6 2009ROBIN L. CHAZDON especialización de hábitat; biodiversidad forestal; bosque secundario; bosque tropical; sucesión Abstract:,In the wake of widespread loss of old-growth forests throughout the tropics, secondary forests will likely play a growing role in the conservation of forest biodiversity. We considered a complex hierarchy of factors that interact in space and time to determine the conservation potential of tropical secondary forests. Beyond the characteristics of local forest patches, spatial and temporal landscape dynamics influence the establishment, species composition, and persistence of secondary forests. Prospects for conservation of old-growth species in secondary forests are maximized in regions where the ratio of secondary to old-growth forest area is relatively low, older secondary forests have persisted, anthropogenic disturbance after abandonment is relatively low, seed-dispersing fauna are present, and old-growth forests are close to abandoned sites. The conservation value of a secondary forest is expected to increase over time, as species arriving from remaining old-growth forest patches accumulate. Many studies are poorly replicated, which limits robust assessments of the number and abundance of old-growth species present in secondary forests. Older secondary forests are not often studied and few long-term studies are conducted in secondary forests. Available data indicate that both old-growth and second-growth forests are important to the persistence of forest species in tropical, human-modified landscapes. Resumen:,A raíz de la pérdida generalizada de los bosques maduros en el trópico, los bosques secundarios probablemente jugarán un mayor papel en la conservación de la biodiversidad forestal. Consideramos una jerarquía compleja de factores que interactúan en el espacio y tiempo para determinar el potencial de conservación de los bosques tropicales secundarios. Más allá de las características de los fragmentos de bosque locales, la dinámica espacial y temporal del paisaje influye en el establecimiento, la composición de especies y la persistencia de bosques secundarios. Los prospectos para la conservación de especies primarias en los bosques secundarios se maximizan en regiones donde la proporción de superficie de bosque maduro-bosque secundario es relativamente baja, los bosques secundarios más viejos han persistido, la perturbación antropogénica después del abandono es relativamente baja, hay presencia de fauna dispersora de semillas y donde hay bosques primarios cerca de sitios abandonados. Se espera que el valor de conservación de un bosque secundario incremente en el tiempo, a medida que se acumulan especies provenientes de los fragmentos de bosque primario remanentes. Muchos estudios están pobremente replicados, lo que impide evaluaciones robustas del número y abundancia de especies primarias presentes en bosques secundarios. Los bosques secundarios más viejos generalmente no son estudiados y son pocos los estudios a largo plazo en bosques secundarios. Los datos disponibles indican que tanto los bosques primarios como los secundarios son importantes para la persistencia de especies forestales en paisajes tropicales modificados por humanos. [source] Probing the corticospinal link between the motor cortex and motoneurones: some neglected aspects of human motor cortical functionACTA PHYSIOLOGICA, Issue 4 2010N. C. Petersen Abstract This review considers the operation of the corticospinal system in primates. There is a relatively widespread cortical area containing corticospinal outputs to a single muscle and thus a motoneurone pool receives corticospinal input from a wide region of the cortex. In addition, corticospinal cells themselves have divergent intraspinal branches which innervate more than one motoneuronal pool but the synergistic couplings involving the many hand muscles are likely to be more diverse than can be accommodated simply by fixed patterns of corticospinal divergence. Many studies using transcranial magnetic stimulation of the human motor cortex have highlighted the capacity of the cortex to modify its apparent excitability in response to altered afferent inputs, training and various pathologies. Studies using cortical stimulation at ,very low' intensities which elicit only short-latency suppression of the discharge of motor units have revealed that the rapidly conducting corticospinal axons (stimulated at higher intensities) drive motoneurones in normal voluntary contractions. There are also major non-linearities generated at a spinal level in the relation between corticospinal output and the output from the motoneurone pool. For example, recent studies have revealed that the efficacy of the human corticospinal connection with motoneurones undergoes activity-dependent changes which influence the size of voluntary contractions. Hence, corticospinal drives must be sculpted continuously to compensate for the changing functional efficacy of the descending systems which activate the motoneurones. This highlights the need for proprioceptive monitoring of movements to ensure their accurate execution. [source] Gazing at the Hand: A Foucaultian View of the Teaching of Manipulative Skills to Introductory Chemistry Students in the United States and the Potential for Transforming Laboratory InstructionCURRICULUM INQUIRY, Issue 3 2005STEPHEN DEMEO ABSTRACT Many studies of chemistry have described the rise of the academic chemical laboratory and laboratory skills in the United States as a result of famous men, important discoveries, and international influences. What is lacking is a perspective of the manifestations of the balances of power and knowledge between teacher and student. A Foucaultian analysis of the teaching of manipulative skills to the introductory student in high school and college in the United States during the later half of the 19th and into the 20th century has provided such a perspective. The analysis focuses on the body, specifically students' hands, and how this body has been redescribed in terms of time, space, activity, and their combinations. It is argued in the first part of this article that the teaching of manipulative skills in the chemistry laboratory can be characterized by effects of differential forms of power and knowledge, such as those provided by Foucault's ideas of hierarchical observation, normalization, and the examination. Moreover, it is evident that disciplinary techniques primarily focused on the physical hands of the student have been recast to include a new cognitive-physiological space in which the teaching of manipulative skills currently takes place. In the second part of this article, the author describes his own professional development as a laboratory instructor through a series of reflective statements that are critiqued from a Foucaultian perspective. The personal narratives are presented in order to pro- vide science educators with an alternative way for their students to think about the relationship between one's manipulative skills and the quality of their data. The pedagogical approach is related to the maturation process of the chemist and contextualized in the current paradigm of laboratory practice, inquiry-based science education. [source] Analysis of force generation during flagellar assembly through optical trapping of free-swimming Chlamydomonas reinhardtiiCYTOSKELETON, Issue 3 2005Rachel Patton McCord Abstract Many studies have used velocity measurements, waveform analyses, and theoretical flagella models to investigate the establishment, maintenance, and function of flagella of the biflagellate green algae Chlamydomonas reinhardtii. We report the first direct measurement of Chlamydomonas flagellar swimming force. Using an optical trap ("optical tweezers") we detect a 75% decrease in swimming force between wild type (CC124) cells and mutants lacking outer flagellar dynein arms (oda1). This difference is consistent with previous estimates and validates the force measurement approach. To examine mechanisms underlying flagella organization and function, we deflagellated cells and examined force generation during flagellar regeneration. As expected, fully regenerated flagella are functionally equivalent to flagella of untreated wild type cells. However, analysis of swimming force vs. flagella length and the increase in force over regeneration time reveals intriguing patterns where increases in force do not always correspond with increases in length. These investigations of flagellar force, therefore, contribute to the understanding of Chlamydomonas motility, describe phenomena surrounding flagella regeneration, and demonstrate the advantages of the optical trapping technique in studies of cell motility. Cell Motil. Cytoskeleton 61:137,144, 2005. © 2005 Wiley-Liss, Inc. [source] Cardiac anxiety in people with and without coronary atherosclerosis,DEPRESSION AND ANXIETY, Issue 10 2008Craig D. Marker Ph.D. Abstract Many studies have shown that cardiac anxiety when occurring in the absence of coronary artery disease is common and quite costly. The Cardiac Anxiety Questionnaire (CAQ) is an 18-item self-report measure that assesses anxiety related to cardiac symptoms. To better understand the construct of cardiac anxiety, a factor analysis was conducted on CAQ data from 658 individuals who were self or physician-referred for electron beam tomographic screening to determine whether clinically significant coronary atherosclerosis was present. A four-factor solution was judged to provide the best fit with the results reflecting the following factor composition: heart-focused attention, avoidance of activities that bring on symptoms, worry or fear regarding symptoms, and reassurance-seeking. Factorial invariance across groups was also assessed to determine whether the factor structure of the CAQ was similar in individuals with and without clear evidence of coronary atherosclerosis. The factor structure of the CAQ did not differ between the two groups. However, the group without coronary atherosclerosis had significantly higher mean scores on their attention and worry/fear factors suggesting that people without a diagnosed cardiac condition pay more attention to and worry more about their cardiac-related symptoms than those people who have coronary atherosclerosis. Depression and Anxiety 2007. Published 2007 Wiley-Liss, Inc. [source] Non-remission of depression in the general population as assessed by the HAMD-7 scaleDEPRESSION AND ANXIETY, Issue 5 2008Andrew G. Bulloch Ph.D. Abstract Remission from the symptoms of depression is the optimal outcome for depression treatment. Many studies have assessed the frequency of treatment, but there are none that have estimated the frequency of treated remission in the general population. We addressed this issue in the population of Alberta using a brief Hamilton Depression Rating Scale (HAMD)-7 scale (recently validated against the HAMD-17 scale in a clinical setting) that has been proposed as a suitable indicator for remission in primary care. We used data from a survey conducted within the Alberta Depression Initiative in 2005 (n=3,345 adults), to produce a population-based estimate of the number of respondents taking antidepressant medication for depression. From this group we selected a subpopulation that did not screen positive when the MINI module for major depression was administered (i.e., who did not have an active episode). Non-remission in this subpopulation was assessed with a version of the HAMD-7 scale adapted for telephone administration by a nonclinician. Of the survey respondents, 189 reported taking antidepressant medication for depression. Of these, 115 were found not to have an active episode. However, 49.0% of this subpopulation was not in remission as evaluated by the HAMD-7. We estimate that 1.3% (95% confidence interval, 0.9,2.0%) of the population is in treated non-remission for depression. Our study indicates a substantial degree of non-remission from depression in individuals taking antidepressants in the general population. This suggests that, in addition to increasing the frequency of treatment, increasing the effectiveness of treatment can have an impact on population health. Depression and Anxiety 0:1,5, 2007. © 2007 Wiley-Liss, Inc. [source] Memory and prefrontal functions in earthquake survivors: differences between current and past post-traumatic stress disorder patientsACTA PSYCHIATRICA SCANDINAVICA, Issue 1 2009E. Eren-Koçak Objective:, Many studies reported deficits in cognitive functions in post-traumatic stress disorder (PTSD). Most were, however, conducted on man-made trauma survivors. The high comorbidity of alcohol use and depression with PTSD in these studies further complicated the interpretation of their results. We compared prefrontal lobe functions and memory in three earthquake survivor groups: current PTSD, past PTSD and no PTSD. We hypothesized that prefrontal performances of the current and past PTSD groups would be worse than that of control group. Method:, Survivors of the 1999 earthquakes in Turkey were evaluated for current and lifetime PTSD. Memory and prefrontal functions were assessed by a neuropsychological test battery. Results:, Current PTSD patients performed worse on attention, verbal memory, verbal fluency, and psychomotor speed. Past PTSD group was similar to the controls on most cognitive measures, except for their vulnerability to proactive interference and low performance in verbal fluency for animal names. Conclusion:, Our findings indicate that the prefrontal organization and monitorization of verbally processed information are defective in earthquake-related PTSD patients, more so in the current PTSD group. [source] Usefulness of lavage cytology during endoscopic transpapillary catheterization into the gallbladder in the cytological diagnosis of gallbladder diseaseDIAGNOSTIC CYTOPATHOLOGY, Issue 6 2009Ph.D., Yoshiki Naito M.D. Abstract Many studies have reported methods of cell collection involving percutaneous transhepatic cholangiodrainage (PTCD) and fine-needle aspiration cytology for the diagnosis of gallbladder disease. However, few studies have described the use of a transpapillary approach, i.e., endoscopic transpapillary catheterization into the gallbladder (ETCG). In this study, we analyzed cells collected by ETCG to evaluate its usefulness in the cytological diagnosis of gallbladder disease. The subjects were 19 patients who had undergone ETCG for the diagnosis of gallbladder disease. Of these patients, 11 and 8 had gallbladder cancer and benign gallbladder disease, respectively. We also evaluated the diagnostic accuracy of PTCD cytology performed in 15 patients with gallbladder cancer. Specimens were cytologically diagnosed as normal or benign, indeterminate, suspected malignancy, malignant, and inadequate in 47% (9/19), 11% (2/19), 0% (0/19), 37% (7/19), and 5% (1/19) of patients, respectively. Specimens were diagnosed as malignant, indeterminate, normal or benign, and inadequate in 7, 2, 1, and 1, respectively, of the 11 patients diagnosed with gallbladder cancer. The sensitivity and specificity of ETCG cytology were 78 and 100%, respectively, whereas the diagnostic accuracy of PTCD cytology was 20% (3/15). None of the patients developed complications of ETCG. Despite its technical difficulty, ETCG for bile cytology allows the collection of adequate cell numbers from patients with benign disease or gallbladder cancer and facilitates a cytological diagnosis, making it a useful method for collecting cells. Diagn. Cytopathol. 2009. © 2009 Wiley-Liss, Inc. [source] HBME-1 and CK19 are highly discriminatory in the cytological diagnosis of papillary thyroid carcinomaDIAGNOSTIC CYTOPATHOLOGY, Issue 8 2008FRCPA, Min-En Nga MRCPath Abstract The cytologic diagnosis of papillary thyroid carcinoma is straightforward in most instances. However, there are some mimics including goitrous nodules and Hurthle cell neoplasms. Many studies have shown the combination of HBME-1 and CK19 expression to be useful in reaching a correct histologic diagnosis on tissue sections. We aim to assess the value of these markers in the setting of cell blocks prepared from needle aspiration specimens. We performed immunohistochemical staining of HBME-1 and CK19 on cell block material from 22 thyroid nodules that also had follow-up histology. Both CK19 and HBME-1 were strongly positive in all nine cases of papillary thyroid carcinoma, the latter showing distinct luminal accentuation. In the non-papillary carcinomas, none showed positivity for both HBME-1 and CK19. Two of six Hurthle cell neoplasms were positive for CK19, however all were negative for HBME-1. One of nine goitrous nodules was strongly positive for HBME-1 with luminal/membranous staining, but this were negative for CK19. The sensitivity, specificity and positive predictive value of HBME-1 in distinguishing between papillary thyroid carcinoma and goitrous nodules/Hurthle cell neoplasms were found to be 100%, 92.9% and 0.9, respectively; and that of HBME-1 and CK19 combination was 100%, 100% and 1. We thus conclude that the combination of positive HBME-1 (luminal/membranous) and CK 19 (cytoplasmic) staining on cell blocks of thyroid cytologic specimens is highly discriminatory in the diagnostic workup for papillary thyroid carcinoma. Diagn. Cytopathol. 2008; 36: 550,556. © 2008 Wiley-Liss, Inc. [source] Pathological gambling: an increasing public health problemACTA PSYCHIATRICA SCANDINAVICA, Issue 4 2001Article first published online: 7 JUL 200 Gambling has always existed, but only recently has it taken on the endlessly variable and accessible forms we know today. Gambling takes place when something valuable , usually money , is staked on the outcome of an event that is entirely unpredictable. It was only two decades ago that pathological gambling was formally recognized as a mental disorder, when it was included in the DSM-III in 1980. For most people, gambling is a relaxing activity with no negative consequences. For others, however, gambling becomes excessive. Pathological gambling is a disorder that manifests itself through the irrepressible urge to wager money. This disorder ultimately dominates the gambler's life, and has a multitude of negative consequences for both the gambler and the people they interact with, i.e. friends, family members, employers. In many ways, gambling might seem a harmless activity. In fact, it is not the act of gambling itself that is harmful, but the vicious cycle that can begin when a gambler wagers money they cannot afford to lose, and then continues to gamble in order to recuperate their losses. The gambler's ,tragic flaw' of logic lies in their failure to understand that gambling is governed solely by random, chance events. Gamblers fail to recognize this and continue to gamble, attempting to control outcomes by concocting strategies to ,beat the game'. Most, if not all, gamblers try in some way to predict the outcome of a game when they are gambling. A detailed analysis of gamblers' selfverbalizations reveals that most of them behave as though the outcome of the game relied on their personal ,skills'. From the gambler's perspective, skill can influence chance , but in reality, the random nature of chance events is the only determinant of the outcome of the game. The gambler, however, either ignores or simply denies this fundamental rule (1). Experts agree that the social costs of pathological gambling are enormous. Changes in gaming legislation have led to a substantial expansion of gambling opportunities in most industrialized countries around the world, mainly in Europe, America and Australia. Figures for the United States' leisure economy in 1996 show gross gambling revenues of $47.6 billion, which was greater than the combined revenue of $40.8 billion from film box offices, recorded music, cruise ships, spectator sports and live entertainment (2). Several factors appear to be motivating this growth: the desire of governments to identify new sources of revenue without invoking new or higher taxes; tourism entrepreneurs developing new destinations for entertainment and leisure; and the rise of new technologies and forms of gambling (3). As a consequence, prevalence studies have shown increased gambling rates among adults. It is currently estimated that 1,2% of the adult population gambles excessively (4, 5). Given that the prevalence of gambling is related to the accessibility of gambling activities, and that new forms of gambling are constantly being legalized throughout most western countries, this figure is expected to rise. Consequently, physicians and mental health professionals will need to know more about the diagnosis and treatment of pathological gamblers. This disorder may be under-diagnosed because, clinically, pathological gamblers usually seek help for the problems associated with gambling such as depression, anxiety or substance abuse, rather than for the excessive gambling itself. This issue of Acta Psychiatrica Scandinavica includes the first national survey of problem gambling completed in Sweden, conducted by Volberg et al. (6). This paper is based on a large sample (N=9917) with an impressively high response rate (89%). Two instruments were used to assess gambling activities: the South Oaks Gambling Screen-Revised (SOGS-R) and an instrument derived from the DSM-IV criteria for pathological gambling. Current (1 year) and lifetime prevalence rates were collected. Results show that 0.6% of the respondents were classified as probable pathological gamblers, and 1.4% as problem gamblers. These data reveal that the prevalence of pathological gamblers in Sweden is significantly less than what has been observed in many western countries. The authors have pooled the rates of problem (1.4%) and probable pathological gamblers (0.6%), to provide a total of 2.0% for the current prevalence. This 2% should be interpreted with caution, however, as we do not have information on the long-term evolution of these subgroups of gamblers; for example, we do not know how many of each subgroup will become pathological gamblers, and how many will decrease their gambling or stop gambling altogether. Until this information is known, it would be preferable to keep in mind that only 0.6% of the Swedish population has been identified as pathological gamblers. In addition, recent studies show that the SOGS-R may be producing inflated estimates of pathological gambling (7). Thus, future research in this area might benefit from the use of an instrument based on DSM criteria for pathological gambling, rather than the SOGS-R only. Finally, the authors suggest in their discussion that the lower rate of pathological gamblers obtained in Sweden compared to many other jurisdictions may be explained by the greater availability of games based on chance rather than games based on skill or a mix of skill and luck. Before accepting this interpretation, researchers will need to demonstrate that the outcomes of all games are determined by other factor than chance and randomness. Many studies have shown that the notion of randomness is the only determinant of gambling (1). Inferring that skill is an important issue in gambling may be misleading. While these are important issues to consider, the Volberg et al. survey nevertheless provides crucial information about gambling in a Scandinavian country. Gambling will be an important issue over the next few years in Sweden, and the publication of the Volberg et al. study is a landmark for the Swedish community (scientists, industry, policy makers, etc.). This paper should stimulate interesting discussions and inspire new, much-needed scientific investigations of pathological gambling. Acta Psychiatrica Scandinavica Guido Bondolfi and Robert Ladouceur Invited Guest Editors References 1.,LadouceurR & WalkerM. The cognitive approach to understanding and treating pathological gambling. In: BellackAS, HersenM, eds. Comprehensive clinical psychology. New York: Pergamon, 1998:588 , 601. 2.,ChristiansenEM. Gambling and the American economy. In: FreyJH, ed. Gambling: socioeconomic impacts and public policy. Thousand Oaks, CA: Sage, 1998:556:36 , 52. 3.,KornDA & ShafferHJ. Gambling and the health of the public: adopting a public health perspective. J Gambling Stud2000;15:289 , 365. 4.,VolbergRA. Problem gambling in the United States. J Gambling Stud1996;12:111 , 128. 5.,BondolfiG, OsiekC, FerreroF. Prevalence estimates of pathological gambling in Switzerland. Acta Psychiatr Scand2000;101:473 , 475. 6.,VolbergRA, AbbottMW, RönnbergS, MunckIM. Prev-alence and risks of pathological gambling in Sweden. Acta Psychiatr Scand2001;104:250 , 256. 7.,LadouceurR, BouchardC, RhéaumeNet al. Is the SOGS an accurate measure of pathological gambling among children, adolescents and adults?J Gambling Stud2000;16:1 , 24. [source] Investigation of coupling between surface processes and induced flow in the lower continental crust as a cause of intraplate seismicityEARTH SURFACE PROCESSES AND LANDFORMS, Issue 12 2006Rob Westaway Abstract Many studies have highlighted the role of coupling between surface processes and flow in the lower continental crust in deforming the crust and creating topographic relief over Quaternary timescales. On the basis of the rheological knowledge gained, it is suggested that intraplate seismicity can also be caused by coupling between surface processes and flow in the lower continental crust. This view is shown to be a natural consequence of the modern idea that isostatic equilibrium is maintained by flow in the weak lower crust in response to erosion and sedimentation. It is supported by a general correlation between the vigour of surface processes and rates of intraplate seismicity, and by instances of seasonal seismicity that correlates with seasonal climate. Human interference in the environment can affect surface loading: for instance, deforestation for agriculture or urban development can cause increased erosion rates; global warming is expected to cause increased storminess (and thus increased erosion rates) and/or global sea-level rise. The possibility of increased rates of seismicity resulting from these processes should thus be considered in future hazard assessment. Copyright © 2006 John Wiley & Sons, Ltd. [source] Hepatopulmonary Syndrome and Right Ventricular Diastolic Functions: An Echocardiographic ExaminationECHOCARDIOGRAPHY, Issue 4 2006Aziz Karabulut M.D. Aim: Liver functions are affected in the course of cardiac diseases, and similarly, liver diseases affect cardiac functions. Many studies in the literature have shown that left ventricular systolic and/or diastolic dysfunction may develop during chronic liver disease. However, there are limited studies investigating right ventricular functions during chronic liver diseases. Methods: A total of 84 patients who had no systolic and/or diastolic dysfunction in the left ventricle (LV) were evaluated; 46 patients with liver cirrhosis; 10 (21.74%) cirrhotic patients with hepatopulmonary syndrome (HPS) (group 1), 36 (78.26) cirrhotic patients without HPS (group 2), and 38 healthy individuals were treated as control. Results: Right ventricular diastolic dysfunction was determined in all patients of group 1 (100%), 26 of group 2 (72.22 %), and 4 of the controls (10.52%) (P < 0.05). Tricuspid deceleration time (dt) was significantly different between the groups (P < 0.05). In addition, right atrium (RA) diameters, right ventricle (RV) diameters, and RV wall thickness were significantly different between the groups (P < 0.05). Pulmonary artery pressure (P < 0.05) and pulmonary vascular resistance (P < 0.05) were also seen to be higher in group 1 than those in group 2 and control group. Conclusions: Right ventricular diastolic dysfunction rate is high in chronic liver diseases. In the presence of HPS, right ventricular diastolic dysfunction is more remarkable in patients than those without HPS. Right ventricular diastolic dysfunction may result in dilatation and hypertrophy in the right heart. [source] Differences in spatial predictions among species distribution modeling methods vary with species traits and environmental predictorsECOGRAPHY, Issue 6 2009Alexandra D. Syphard Prediction maps produced by species distribution models (SDMs) influence decision-making in resource management or designation of land in conservation planning. Many studies have compared the prediction accuracy of different SDM modeling methods, but few have quantified the similarity among prediction maps. There has also been little systematic exploration of how the relative importance of different predictor variables varies among model types and affects map similarity. Our objective was to expand the evaluation of SDM performance for 45 plant species in southern California to better understand how map predictions vary among model types, and to explain what factors may affect spatial correspondence, including the selection and relative importance of different environmental variables. Four types of models were tested. Correlation among maps was highest between generalized linear models (GLMs) and generalized additive models (GAMs) and lowest between classification trees and GAMs or GLMs. Correlation between Random Forests (RFs) and GAMs was the same as between RFs and classification trees. Spatial correspondence among maps was influenced the most by model prediction accuracy (AUC) and species prevalence; map correspondence was highest when accuracy was high and prevalence was intermediate (average prevalence for all species was 0.124). Species functional type and the selection of climate variables also influenced map correspondence. For most (but not all) species, climate variables were more important than terrain or soil in predicting their distributions. Environmental variable selection varied according to modeling method, but the largest differences were between RFs and GLMs or GAMs. Although prediction accuracy was equal for GLMs, GAMs, and RFs, the differences in spatial predictions suggest that it may be important to evaluate the results of more than one model to estimate the range of spatial uncertainty before making planning decisions based on map outputs. This may be particularly important if models have low accuracy or if species prevalence is not intermediate. [source] Capital-skill Complementarity and Inequality: A Macroeconomic AnalysisECONOMETRICA, Issue 5 2000Per Krusell The supply and price of skilled labor relative to unskilled labor have changed dramatically over the postwar period. The relative quantity of skilled labor has increased substantially, and the skill premium, which is the wage of skilled labor relative to that of unskilled labor, has grown significantly since 1980. Many studies have found that accounting for the increase in the skill premium on the basis of observable variables is difficult and have concluded implicitly that latent skill-biased technological change must be the main factor responsible. This paper examines that view systematically. We develop a framework that provides a simple, explicit economic mechanism for understanding skill-biased technological change in terms of observable variables, and we use the framework to evaluate the fraction of variation in the skill premium that can be accounted for by changes in observed factor quantities. We find that with capital-skill complementarity, changes in observed inputs alone can account for most of the variations in the skill premium over the last 30 years. [source] Quantitation of reduced glutathione and cysteine in human immunodeficiency virus-infected patientsELECTROPHORESIS, Issue 10-11 2004Elena Sbrana Abstract Plasma viral load (VL) values and CD4+ cell count are employed clinically for initiation of therapy in the treatment of patients infected with human immunodeficiency virus (HIV), as previous clinical studies have shown a marked prevalence of acquired immunodeficiency sydrome (AIDS) development in seropositive individuals with VL values over 30,000 copies/mL. Many studies have shown that reduced glutathione (GSH) and cysteine (Cys) deficiency play an important role in the infection. We have developed capillary zone electrophoresis (CZE)-based assays and have used them to investigate the relationship between plasma and intracellular thiol levels and HIV-1 viremia in plasma. Blood samples from healthy volunteers and seropositive patients undergoing different antiretroviral regimes were analyzed in the study. The VL assay was based on CZE-UV detection of viral RNA at 260 nm. Determination of endogenous reduced Cys and GSH was achieved by CZE-UV detection of their mercurial complexes at 200 nm. We found that a decrease in GSH and Cys levels may be associated with disease progress. In fact, reduced GSH and Cys levels appear progressively reduced with increasing VL. [source] The effects of chronic nitrogen fertilization on alpine tundra soil microbial communities: implications for carbon and nitrogen cyclingENVIRONMENTAL MICROBIOLOGY, Issue 11 2008Diana R. Nemergut Summary Many studies have shown that changes in nitrogen (N) availability affect primary productivity in a variety of terrestrial systems, but less is known about the effects of the changing N cycle on soil organic matter (SOM) decomposition. We used a variety of techniques to examine the effects of chronic N amendments on SOM chemistry and microbial community structure and function in an alpine tundra soil. We collected surface soil (0,5 cm) samples from five control and five long-term N-amended plots established and maintained at the Niwot Ridge Long-term Ecological Research (LTER) site. Samples were bulked by treatment and all analyses were conducted on composite samples. The fungal community shifted in response to N amendments, with a decrease in the relative abundance of basidiomycetes. Bacterial community composition also shifted in the fertilized soil, with increases in the relative abundance of sequences related to the Bacteroidetes and Gemmatimonadetes, and decreases in the relative abundance of the Verrucomicrobia. We did not uncover any bacterial sequences that were closely related to known nitrifiers in either soil, but sequences related to archaeal nitrifiers were found in control soils. The ratio of fungi to bacteria did not change in the N-amended soils, but the ratio of archaea to bacteria dropped from 20% to less than 1% in the N-amended plots. Comparisons of aliphatic and aromatic carbon compounds, two broad categories of soil carbon compounds, revealed no between treatment differences. However, G-lignins were found in higher relative abundance in the fertilized soils, while proteins were detected in lower relative abundance. Finally, the activities of two soil enzymes involved in N cycling changed in response to chronic N amendments. These results suggest that chronic N fertilization induces significant shifts in soil carbon dynamics that correspond to shifts in microbial community structure and function. [source] Studies on the effect of soil aging on the toxicity of pyrene and phenanthrene to a soil-dwelling springtailENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2002Line E. Sverdrup Abstract Soil samples spiked with five concentrations of pyrene and phenanthrene were aged for 0, 10, 40, and 120 d before toxicity was investigated using a standardized bioassay with the soil-dwelling collembolan Folsomia fimetaria L. Toxic effects were measured as reductions in survival and reproductive output after 3 weeks of exposure. Both pyrene and phenanthrene were degraded in the test system during storage, phenanthrene to a higher degree than pyrene. However, when toxic effects of the tested substances were calculated on the basis of measured concentrations of the parent compounds, toxicity was unaffected by storage for up to 120 d. Many studies have shown a negative correlation between aging and the biodegradation of polycyclic aromatic hydrocarbons (PAHs), indicating a reduction in the bioavailability of PAHs to micro-organisms with time. Our results indicate that a reduction in toxicity, as related to the measured concentrations of the parent compounds in the soil, may not always be expected for aged soils. Provided that metabolites of pyrene and phenanthrene did not significantly contribute to the toxicity in aged soil samples, a possible explanation for the absence of aging effects is the high test concentrations used in combination with the low content of organic carbon (1.6%) in the test soil. [source] Assessing the impacts of grazing levels on bird density in woodland habitat: a Bayesian approach using expert opinionENVIRONMETRICS, Issue 7 2005Petra M. Kuhnert Abstract Many studies on birds focus on the collection of data through an experimental design, suitable for investigation in a classical analysis of variance (ANOVA) framework. Although many findings are confirmed by one or more experts, expert information is rarely used in conjunction with the survey data to enhance the explanatory and predictive power of the model. We explore this neglected aspect of ecological modelling through a study on Australian woodland birds, focusing on the potential impact of different intensities of commercial cattle grazing on bird density in woodland habitat. We examine a number of Bayesian hierarchical random effects models, which cater for overdispersion and a high frequency of zeros in the data using WinBUGS and explore the variation between and within different grazing regimes and species. The impact and value of expert information is investigated through the inclusion of priors that reflect the experience of 20 experts in the field of bird responses to disturbance. Results indicate that expert information moderates the survey data, especially in situations where there are little or no data. When experts agreed, credible intervals for predictions were tightened considerably. When experts failed to agree, results were similar to those evaluated in the absence of expert information. Overall, we found that without expert opinion our knowledge was quite weak. The fact that the survey data is quite consistent, in general, with expert opinion shows that we do know something about birds and grazing and we could learn a lot faster if we used this approach more in ecology, where data are scarce. Copyright © 2005 John Wiley & Sons, Ltd. [source] Temporal lobe epilepsy surgery and the quest for optimal extent of resection: A reviewEPILEPSIA, Issue 8 2008Johannes Schramm Summary The efficacy of surgery to treat drug-resistant temporal lobe epilepsy (TLE) has been demonstrated in a prospective randomized trial. It remains controversial which resection method gives best results for seizure freedom and neuropsychological function. This review of 53 studies addressing extent of resection in surgery for TLE identified seven prospective studies of which four were randomized. There is considerable variability between the intended resection and the volumetrically assessed end result. Even leaving hippocampus or amygdalum behind can result in seizure freedom rates around 50%. Most authors found seizure outcome in selective amygdalohippocampectomy (SAH) to be similar to that of lobectomy and there is considerable evidence for better neuropsychological outcome in SAH. Studies varied in the relationship between extent of mesial resection and seizure freedom, most authors finding no positive correlation to larger mesial resection. Electrophysiological tailoring saw no benefit from larger resection in 6 of 10 studies. It must be concluded that class I evidence concerning seizure outcome related to type and extent of resection of mesial temporal lobe structures is rare. Many studies are only retrospective and do not use MRI volumetry. SAH appears to have similar seizure outcome and a better cognitive outcome than TLR. It remains unclear whether a larger mesial resection extent leads to better seizure outcome. [source] Adjustment of Parental Investment in the Dung Beetle Onthophagus atripennis (Col., Scarabaeidae)ETHOLOGY, Issue 12 2006Shigeki Kishi If parents can invest resources optimally per offspring, they should adjust the amount of investment in an offspring according to environmental heterogeneity. Many studies have demonstrated changes in egg size or the amount of resource supplied in response to environmental heterogeneity. However, it remains unclear whether parents simply know the resource type a priori or can assess resource quality and adjust the quantity of investment accordingly. We examined the parental capability to adjust the amount of investment per offspring by providing Onthophagus atripennis dung beetle parents with one of three dung types of different quality: monkey dung (high quality), cow dung (low quality), or a mixture of monkey and cow dung (medium quality). The beetle parents cooperatively produce dung brood masses each with one egg under the ground. The size of a brood mass, on which a larva can only feed until adult, represents a large part of the amount of investment. Parents produced a greater number of smaller brood masses given high-quality resource, while they compensated for low quality of the resource by providing a larger amount of the resource, at the cost of offspring number. However, despite this compensation in the amount of food, offspring raised on low-quality food was still smaller than offspring raised on high-quality food. Thus, O. atripennis parents assessed resource quality partly and adjusted the amount of resource provided for their offspring. [source] Learner-control vs. program-control instructional multimedia: a comparison of two interactions when teaching principles of orthodontic appliancesEUROPEAN JOURNAL OF DENTAL EDUCATION, Issue 4 2005M. Aly Abstract Background:, Many studies have compared computer assisted learning (CAL) to more traditional learning formats and have shown CAL to be as effective as or superior to the alternative resources. However, there are only scarce attempts to show which style of CAL leads to the best learning outcomes in orthodontics. Aim:, To compare the effectiveness of a learner-control (group A) vs. program-control (group B) multimedia learning environment courseware packages regarding knowledge, understanding and transfer of content when applied to teaching principles of orthodontic appliances to undergraduate students. Methods:, Pre- and post-test assessments of undergraduate dental students (n = 30) who either studied a learner-control multimedia learning environment courseware package (n = 15) or a program-control version (n = 15) on equivalent material of the orthodontic appliances curriculum. Both groups were evaluated by means of multiple-choice questions covering knowledge, understanding and application. A one-way ANOVA was carried out in order to check for statistical difference between the two groups. The P -value was set at 0.05. Results:, There was no difference in prior knowledge between both groups at baseline. Although, both groups significantly improved their scores after having studied the course, no significant difference was found between both groups in relation to answers to questions about knowledge, understanding and application. Conclusions:, In this study, the learner-control instructional multimedia program was found to be as effective as the program-control version when teaching principles of the orthodontic appliances to undergraduate students. The focus needs to be on improving the value of CAL. Comparative evaluations of how different CAL approaches compare with or complement one another are certainly needed. [source] Independent on-line control of the two hands during bimanual reachingEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2004Jörn Diedrichsen Abstract Many studies on bimanual coordination have shown that people exhibit a preference for mirror-symmetric movements. We demonstrate that this constraint is absent when bimanual reaching movements are made to visual targets. We investigated the ability of humans to make on-line adjustments during such movements when one or both targets were displaced during the initial phase of the movements. Adjustments were as efficient during bimanual as unimanual movements, even when two adjustments had to be made simultaneously. When one target was displaced in the bimanual condition, the hand reaching to that target adjusted efficiently to the displacement. However, a small transient perturbation in the trajectory of the other hand was also observed. This perturbation was in the same direction as the displacement, rather than in mirror-symmetric direction. A control experiment demonstrated that these perturbations could be elicited by visual information alone, but that they were also influenced by whether an adjustment was required in the trajectory of the other hand. Our results demonstrate near independent control of the two arms during visually guided reaching. The subtle interference observed between the arms reflects interactions between target-related representations in visual coordinates rather than between movement-related representations in joint- or muscle-coordinates. [source] Variability of the masticatory process during chewing of elastic model foodsEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 6 2000Claire Lassauzay Many studies show a consistent individual chewing pattern; chewing being governed by a pattern generator and regulated by sensory feedback. The aim of this study was to determine the variation in chewing between sessions, replicates and subjects using elastic model foods. Fifteen young male subjects were selected to chew four food products differing in hardness. Four sessions were performed at 1-wk intervals for each subject and, within each session, the four model foods were presented 3 times each. Jaw movement was recorded simultaneously with masseter and anterior temporalis electromyographic activities. Several chewing characteristics increased progressively from one session to the next; the largest increase occurred from the 1st to the 2nd session, with little difference between the last two sessions. No differences were observed between the samples of the same food product within a session. As mastication progressed, the amplitude and speed of the cycles and the muscular work decreased progressively. The first cycle appeared to be very different from the subsequent for all parameters except for occlusal duration. Thus, under our experimental conditions, the origin and amount of variation in chewing patterns were identified and provide information to improve the accuracy and comparability of results in studies of mastication. [source] LEAKY PREZYGOTIC ISOLATION AND POROUS GENOMES: RAPID INTROGRESSION OF MATERNALLY INHERITED DNAEVOLUTION, Issue 4 2005Kai M. A. Chan Abstract Accurate phylogenies are crucial for understanding evolutionary processes, especially species diversification. It is commonly assumed that "good" species are sufficiently isolated genetically that gene genealogies represent accurate phylogenies. However, it is increasingly clear that good species may continue to exchange genetic material through hybridization (introgression). Many studies of closely related species reveal introgression of some genes without others, often with more rapid introgression of maternally inherited chloroplast or mitochondrial DNA (cpDNA, mtDNA). We seek a general explanation for this biased introgression using simple models of common reproductive isolating barriers (RIBs). We compare empirically informed models of prezygotic isolation (for pre- and postinsemination mechanisms of both female choice and male competition) with postzygotic isolation and demonstrate that rate of introgression depends critically upon type of RIB and mode of genetic inheritance (maternal versus biparental versus paternal). Our frequency-dependent prezygotic RIBs allow much more rapid introgression of biparentally and maternally inherited genes than do commonly modeled postzygotic RIBs (especially maternally inherited DNA). After considering the specific predictions in the context of empirical observations, we conclude that our model of prezygotic RIBs is a general explanation for biased introgression of maternally inherited genomic components. These findings suggest that we should use extreme caution when interpreting single gene genealogies as species phylogenies, especially for cpDNA and mtDNA. [source] Effects of Endotoxin Exposure on Cationic Amino Acid Transporter Function in Ovine Peripheral Blood Mononuclear CellsEXPERIMENTAL PHYSIOLOGY, Issue 2 2003Megan F. Clark Rodent models of sepsis differ from clinical human disease in that humans make substantially less whole-body nitric oxide and have different cellular responses to endotoxin. Sheep, when exposed to endotoxin, behave in a manner more similar to humans. Many studies of rodent peripheral blood mononuclear cells (PBMCs) exposed to endotoxin demonstrate increased cationic amino acid transporter function (particularly through the y+ transporter) to supply arginine substrate to upregulated nitric oxide synthase. Whether this is true in sheep is not known. We have studied cationic amino acid transport in sheep PBMCs stimulated with endotoxin, using labelled lysine. PBMCs stimulated both in vitro and in vivo show an initial reduction in total and y+ lysine transport (after 1-2 h exposure to endotoxin): a previously undescribed effect of endotoxin. In in vitro activated cells, the reduction in y+ transport was prevented by the lipoxygenase inhibitor, nordihydroguaretic acid (NDGA), and the phospholipase inhibitor 4-bromophenacyl bromide (4-BPAB), but not cyclohexamide or a number of other inhibitors of intracellular second-messenger pathways. In contrast after 14 h incubation, the expected increase in total and y+ lysine transport was seen. The increase in y+ transport could be prevented by cyclohexamide, dexamethasone, ibuprofen, the protein kinase C inhibitor sphingosine, NDGA and 4-BPAB. These results suggest that in response to endotoxin exposure there is an initial decrease in y+ activity mediated by a lipoxygenase product, followed by a substantial increase in y+ activity mediated by the products of either cyclo-oxygenase or lipoxygenase. Cyclo-oxygenase and/or lipoxygenase inhibition might be useful in reducing arginine transport, and hence nitric oxide production, in these cells. [source] Assembly rules and community models for unicellular organisms: patterns in diatoms of boreal streamsFRESHWATER BIOLOGY, Issue 4 2005JANI HEINO Summary 1. Many studies have addressed either community models (e.g. Clementsian versus Gleasonian gradients) or assembly rules (e.g. nestedness, checkerboards) for higher plant and animal communities, but very few studies have examined different non-random distribution patterns simultaneously with the same data set. Even fewer studies have addressed generalities in the distribution patterns of unicellular organisms, such as diatoms. 2. We studied non-randomness in the spatial distribution and community composition of stream diatoms. Our data consisted of diatom surveys from 47 boreal headwater streams and small rivers in northern Finland. Our analytical approaches included ordinations, cluster analysis, null model analyses, and associated randomisation tests. 3. Stream diatom communities did not follow discrete Clementsian community types, where multiple species occur exclusively in a single community type. Rather, diatom species showed rather individualistic responses, leading to continuous Gleasonian variability in community composition. 4. Although continuous variability was the dominating pattern in the data, diatoms also showed significant nestedness and less overlap in species distribution than expected by chance. However, these patterns were probably only secondary signals from species' individualistic responses to the environment. 5. Although unicellular organisms, such as diatoms, differ from multicellular organisms in several biological characteristics, they nevertheless appear to show largely similar non-random distribution patterns previously found for higher plants and metazoans. [source] Plant functional type classifications in tropical dry forests in Costa Rica: leaf habit versus taxonomic approachesFUNCTIONAL ECOLOGY, Issue 4 2010Jennifer S. Powers Summary 1.,One way to simplify the high taxonomic diversity of plant species in vegetation models is to place species into groups based on shared, dominant traits. Many studies have suggested that morphological and physiological traits of tropical dry forest tree species vary with leaf habit (i.e. leaves from evergreen, deciduous or semi-deciduous species) and thus this characteristic may serve as a useful way to distinguish ecologically meaningful functional types. 2.,In this study we examine whether 10 plant traits vary with leaf habit in replicated leaves and individual trees of 87 species from a tropical dry forest in Costa Rica. We also looked for evidence of phylogenetic conservatism, i.e. closely related species sharing similar trait values compared to more distantly related taxa. 3.,While some of the traits varied within and among individual trees of the same species, interspecific variation accounted for 57,83% of the variance among samples. Four traits in addition to leaf habit showed evidence of phylogenetic conservatism, but these results were strongly dependent on the inclusion of the 18 species of legumes (Fabaceae) in our dataset. Contrary to our predictions, none of the traits we measured differed among leaf habits. However, five traits (wood density, leaf C, leaf N, N/P and C/N) varied significantly between legumes and other functional types. Furthermore, when all high-nitrogen non-legume taxa were compared to the high-nitrogen legumes, six traits excluding leaf N differed significantly, indicating that legumes are functionally different from other tree species beyond high N concentrations. Similarly, the 18 legume taxa (which all have compound leaves) also differed from other compound-leaved species for six traits, thus leaf type does not explain these patterns. 4.,Our main conclusions are that (i) a plant functional type classification based on leaf habit alone has little utility in the tropical dry forest we studied, and (ii) legumes have a different suite of traits including high leaf carbon and wood density in addition to high leaf nitrogen. Whether this result generalizes to other tropical forests is unknown, but merits future research due to the consequences of these traits for carbon storage and ecosystem processes. [source] The role of static stress transfer in mining induced seismic events occurrence, a case study of the Rudna mine in the Legnica-Glogow Copper District in PolandGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2010B. Orlecka-Sikora SUMMARY Seismicity accompanying mining exploitation results from changes in the stress field in the rock mass near the mining excavations caused by human activity. Many studies of the temporal and spatial distribution of mining induced seismicity have provided evidence for interrelations among events. Although a variety of techniques have been applied to quantify the interdependences of mining induced seismic events, the physical mechanism of interactions has not been unequivocally identified. Based on the premise that one possible cause of interactions among seismic events can be static stress transfer, we have verified statistically the role of Coulomb stress transfer in the generation process of mining induced seismicity using a series of seismic events that occurred in the Rudna mine in the Legnica-G,ogów Copper District in Poland. We quantify the triggering and inhibiting effect by the proportion of events in the series, whose locations are consistent with the stress increased and stress decreased zones, respectively. We have found that more than 60 per cent of the analysed seismic events occurred in areas where stress was enhanced due to the occurrence of previous events. The statistical significance of these results is tested by comparing them with the same proportions obtained for 2000 random permutations of the original series of events. The test has indicated that the locations in positive stress changes areas are preferred statistically significantly when the stress changes exceed 0.05 bar. This result turns out to be robust to the errors of the nodal planes determination. [source] Impact of history or onset of chronic medical conditions on higher-level functional capacity among older community-dwelling Japanese adultsGERIATRICS & GERONTOLOGY INTERNATIONAL, Issue 2003Yoshinori Fujiwara Background: Many studies have examined the impact of chronic medical conditions on the age-related decline in basic activities of daily living (BADL) and the instrumental activities of daily living (IADL), but less is known concerning the influence of chronic disease on physical, cognitive, social, and economic aspects of higher-level functional capacity. Methods: Subjects comprised 793 and 725 persons aged 65,84 years, living in an urban and a rural Japanese community, respectively. A baseline interview established any history of chronic medical conditions. Four years later, a second interview again assessed chronic disease, and higher-level functional capacity was evaluated using the Tokyo Metropolitan Institute of Gerontology (TMIG) Index of Competence. Results: Multiple logistic regression analysis revealed that declines in total score and/or any of three subscales of the TMIG Index of Competence were significantly associated with a history of chronic disease, the onset of visual impairment and the development of hearing impairment, even after controlling for the subject's age, gender, educational attainment, and baseline TMIG Index of Competence. Episodes of stroke were significantly associated with declines in IADL. Hypertension, diabetes mellitus, and heart disease were also significantly associated with a decrease in functional competence, although each affected a different subscale of the TMIG Index of Competence. Conclusions: The present results underline the importance of controlling chronic medical conditions through a physically active lifestyle and an appropriate medical regimen in order to limit the age-related decline in functional capacity. [source] | |||||||||||||||||||||||||||||||||||||||||||