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One Explanation (one + explanation)
Selected AbstractsPlant,soil biota interactions and spatial distribution of black cherry in its native and invasive rangesECOLOGY LETTERS, Issue 12 2003Kurt O. Reinhart Abstract One explanation for the higher abundance of invasive species in their non-native than native ranges is the escape from natural enemies. But there are few experimental studies comparing the parallel impact of enemies (or competitors and mutualists) on a plant species in its native and invaded ranges, and release from soil pathogens has been rarely investigated. Here we present evidence showing that the invasion of black cherry (Prunus serotina) into north-western Europe is facilitated by the soil community. In the native range in the USA, the soil community that develops near black cherry inhibits the establishment of neighbouring conspecifics and reduces seedling performance in the greenhouse. In contrast, in the non-native range, black cherry readily establishes in close proximity to conspecifics, and the soil community enhances the growth of its seedlings. Understanding the effects of soil organisms on plant abundance will improve our ability to predict and counteract plant invasions. [source] Blushing after a moral transgression in a prisoner's dilemma game: appeasing or revealing?EUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 5 2002Peter J. de Jong This study investigated the alleged remedial effects of blushing in the context of real-time interactions. Therefore, 30 pairs of prosocial individuals participated in a prisoner's dilemma ,game'. The experiment was framed as an objective test of moral behaviour. To elicit a shameful moral transgression, one individual of each pair was instructed to select the non-habitual cheat-option on a pre-defined target trial. Supporting the idea that violation of shared rules elicits blushing, the defectors displayed a blush on the target trial. Yet, unexpectedly, there was a negative relationship between the observed blush intensity and the trustworthiness attributed to the defectors. One explanation might be that the ,victims' used the blush response to deduce and interpret the defector's motive. As the antecedent behaviour involved in the present context was not completely unambiguous with respect to the perpetrators' motive (e.g. innocent playing around vs. maximizing outcomes) the observers might have interpreted blushing as signaling that the situation should be interpreted as an intentional violation of a social standard. Together the available evidence suggests that only in the context of unambiguous antecedent behaviours blushing has remedial effects, whereas in ambiguous situations blushing has undesirable revealing effects. Copyright © 2002 John Wiley & Sons, Ltd. [source] Model complexity versus scatter in fatigueFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 11 2004T. SVENSSON ABSTRACT Fatigue assessment in industry is often based on simple empirical models, such as the Wöhler curve or the Paris' law. In contrast, fatigue research to a great extent works with very complex models, far from the engineering practice. One explanation for this discrepancy is that the scatter in service fatigue obscures many of the subtle phenomena that can be studied in a laboratory. Here we use a statistical theory for stepwise regression to investigate the role of scatter in the choice of model complexity in fatigue. The results suggest that the amount of complexity used in different design concepts reflects the appreciated knowledge about input parameters. The analysis also points out that even qualitative knowledge about the neglected complexity may be important in order to avoid systematic errors. [source] ,Beyond Left and Right': The New Partisan Politics of WelfareGOVERNANCE, Issue 2 2000Fiona Ross The ,new politics of the welfare state,' the term coined by Pierson (1996) to differentiate between the popular politics of welfare expansion and the unpopular politics of retrenchment, emphasizes a number of factors that distinguish countries' capacities to pursue contentious measures and avoid electoral blame. Policy structures, vested interests, and institutions play a prominent role in accounting for cross-national differences in leaders' abilities to diffuse responsibility for divisive initiatives. One important omission from the ,new politics' literature, however, is a discussion of partisan politics. ,Old' conceptualizations of the political right and left are implicitly taken as constants despite radical changes in the governing agenda of many leftist parties over the last decade. Responding to this oversight, Castles (1998) has recently probed the role of parties with respect to aggregate government expenditures, only to concludethat parties do not matter under ,conditions of constraint.' This article contends that parties are relevant to the ,new politics' and that, under specified institutional conditions, their impact is counterintuitive. In some notable cases the left has had more effect inbruising the welfare state than the right. One explanation for these cross-cutting tendencies is that parties not only provide a principal source of political agency, they also serve as strategies, thereby conditioning opportunities for political leadership. By extension, they need to be situatedwithin the ,new politics' constellation of blame-avoidance instruments. [source] Are Hispanic Immigrants in English-Only States at a Homeownership Disadvantage?GROWTH AND CHANGE, Issue 1 20031990 U.S. Censuses, Evidence from the 1980 Utilizing data from the 1980 and 1990 U.S. census, this study investigates whether the passage of official-English legislation at the state level during the 1980s affected the housing acquisition of foreign-born Hispanics. The results suggest that both limited-English-proficient (LEP) and English-fluent Hispanic immigrants who resided in states that passed English-only legislation were less likely to acquire a home during the 1980s compared to their counterparts in other areas. Consistent with economic theory, however, the group that seemed to be most affected included older LEP residents. One explanation for these findings is that the official-English legislation mirrored growing xenophobia against foreign-born Hispanics, resulting in additional social stratification on the basis of ethnicity in housing markets. [source] Does the Impact of Managed Care on Substance Abuse Treatment Services Vary by Provider Profit Status?HEALTH SERVICES RESEARCH, Issue 6p1 2005Todd A. Olmstead Objective. To extend our previous research by determining whether, and how, the impact of managed care (MC) on substance abuse treatment (SAT) services differs by facility ownership. Data Sources. The 2000 National Survey of Substance Abuse Treatment Services, which is designed to collect data on service offerings and other characteristics of SAT facilities in the U.S. These data are merged with data from the 2002 Area Resource File, a county-specific database containing information on population and MC activity. We use data on 10,513 facilities, virtually a census of all SAT facilities. Study Design. For each facility ownership type (for-profit [FP], not-for-profit [NFP], public), we estimate the impact of MC on the number and types of SAT services offered. We use instrumental variables techniques that account for possible endogeneity between facilities' involvement in MC and service offerings. Principal Findings. We find that the impact of MC on SAT service offerings differs in magnitude and direction by facility ownership. On average, MC causes FPs to offer approximately four additional services, causes publics to offer approximately four fewer services, and has no impact on the number of services offered by NFPs. The differential impact of MC on FPs and publics appears to be concentrated in therapy/counseling, medical testing, and transitional services. Conclusion. Our findings raise policy concerns that MC may reduce the quality of care provided by public SAT facilities by limiting the range of services offered. On the other hand, we find that FP clinics increase their range of services. One explanation is that MC results in standardization of service offerings across facilities of different ownership type. Further research is needed to better understand both the specific mechanisms of MC on SAT and the net impact on society. [source] Brain region binding of the D2/3 agonist [11C]-(+)-PHNO and the D2/3 antagonist [11C]raclopride in healthy humansHUMAN BRAIN MAPPING, Issue 4 2008Ariel Graff-Guerrero Abstract The D2 receptors exist in either the high- or low-affinity state with respect to agonists, and while agonists bind preferentially to the high-affinity state, antagonists do not distinguish between the two states. [11C]-(+)-PHNO is a PET D2agonist radioligand and therefore provides a preferential measure of the D2high receptors. In contrast, [11C]raclopride is an antagonist radioligand and thus binds with equal affinity to the D2 high- and low-affinity states. The aim was to compare the brain uptake, distribution and binding characteristics between [11C]-(+)-PHNO and [11C]raclopride in volunteers using a within-subject design. Both radioligands accumulated in brain areas rich in D2/D3 -receptors. However, [11C]-(+)-PHNO showed preferential uptake in the ventral striatum and globus pallidus, while [11C]raclopride showed preferential uptake in the dorsal striatum. Mean binding potentials were higher in the putamen (4.3 vs. 2.8) and caudate (3.4 vs 2.1) for [11C]raclopride, equal in the ventral-striatum (3.4 vs. 3.3), and higher in the globus pallidus for [11C]-(+)-PHNO (1.8 vs. 3.3). Moreover [11C]-(+)-PHNO kinetics in the globus pallidus showed a slower washout than other regions. One explanation for the preferential binding of [11C]-(+)-PHNO in the globus pallidus and ventral-striatum could be the presence of a greater proportion of high- vs. low-affinity receptors in these areas. Alternatively, the observed distribution could also be explained by a preferential binding of D3 -over-D2 with [11C]-(+)-PHNO. This differential binding of agonist vs. antagonist radioligand, especially in the critically important region of the limbic striatum/pallidum, offers new avenues to investigate the role of the dopamine system in health and disease. Hum Brain Mapp 2008. © 2007 Wiley-Liss, Inc. [source] MDM2 SNP309 T>G alone or in combination with the TP53 R72P polymorphism does not appear to influence disease expression and age of diagnosis of colorectal cancer in HNPCC patientsINTERNATIONAL JOURNAL OF CANCER, Issue 3 2007Bente A. Talseth Abstract Disease expression in hereditary nonpolyposis colorectal cancer (HNPCC) cannot be readily explained by mutation site in the respective DNA mismatch repair genes associated with this disorder. One explanation is the role of modifying genes that can either promote or prevent disease development on a background of increased risk. Two single nucleotide polymorphisms in MDM2 and TP53 have been shown to be associated with younger ages of disease onset in HNPCC (TP53) and Li-Fraumeni syndrome (MDM2). In this study 220 HNPCC patients were examined, from Australia and Poland, all characterized at the molecular level to determine the frequency of the MDM2 SNP309 T>G and to assess its influence on disease expression. The results were then pooled with the results of a previous study to assess the combined influence of the MDM2 SNP309 T>G and TP53 SNP R72P. A significant difference was observed between CRC patients and unaffected MMR gene mutation carriers over the age of 45 years (p = 0.01). The unaffected MMR gene mutation carriers over the age of 45 years who carry the G allele have a reduced risk of developing CRC. The results indicate that the MDM2 SNP309, alone or in combination with TP53 R72P, does not influence age of diagnosis of CRC in individuals with HNPCC. In conclusion, the data indicates the G allele of MDM2 SNP309 might have a protective effect on disease development in HNPCC patients and that age of diagnosis of CRC is not associated with MDM2 SNP309 or TP53 R72P either as single SNPs or combined. © 2006 Wiley-Liss, Inc. [source] Predicting the relationship between local and regional species richness from a patch occupancy dynamics modelJOURNAL OF ANIMAL ECOLOGY, Issue 2 2000B. Hugueny Summary 1.,A linear relationship between the number of species in ecological communities (local richness) and the species pools from which the communities are drawn (regional richness) suggests that species interactions are not sufficient to limit local richness and that communities are not saturated with species. Instead, this relationship implies that communities are open to regional influences and are interlinked by dispersal. 2.,Here we show how the linear relationship between local and regional richness in real, noninteractive, assemblages of cynipid gall wasps on California oaks, can be predicted from a simple patch-occupancy model. 3.,One cynipid assemblage has been surveyed for 3 years, allowing for crude estimates of colonization and extinction rates per patch. Using the mainland/island model of patch occupancy dynamics, these rates are combined with the observed number of cynipid species associated with each oak species (regional richness) to predict the expected local species richness in each patch. Assuming that species are independently distributed among localities, the expected variance in species richness among localities is also computed. 4.,The model is then tested on an independent data set. When differences in sampling effort (number of surveyed trees per locality) were accounted for, the regression equation relating observed (n = 41) to predicted local species richness does not differ statistically from the line of perfect agreement. The residuals are also distributed according to the predicted variance. 5.,Although not statistically significant, the variance in local richness appears to be slightly underestimated by the model. One explanation may be that cynipid species display some positive covariance in their distribution among localities, that is, groups of species occur together in given localities more frequently than would be expected by chance. Variance ratio tests identified statistically positive covariance within cynipid assemblages for three oaks species. 6.,The close fit of the model to the data supports the theoretical scenario for noninteractive communities, that the slope of the local,regional richness relationship and patch-occupancy processes are different expressions of the same phenomenon. [source] Refuge habitats modify impact of insecticide disturbance on carabid beetle communitiesJOURNAL OF APPLIED ECOLOGY, Issue 2 2001Jana C. Lee Summary 1Carabid beetles are polyphagous predators that can act as biological control agents of insect pests and weeds. While current agricultural practices often create a harsh environment, habitat management such as the establishment of within-field refuges has been proposed to enhance carabid beetle abundance and impact. We examined the joint effects of refuge habitats and insecticide application on carabid activity density (parameter of population density and relative activity) and species composition in a cornfield. 2Our 2-year study comprised four treatments: (i) ,refuge/,insecticide; (ii) +refuge/,insecticide; (iii) ,refuge/+insecticide; (iv) +refuge/+insecticide. Refuge strips consisted of grasses, legumes and perennial flowering plants. ,,Refuge' strips were planted with corn and not treated with insecticide. 3Before planting and insecticide application, carabid activity density in the crop areas was similar across all treatments. Insecticide application immediately reduced carabid activity density and altered community composition in the crop area. 4Refuge strips had significantly higher activity density of beetles than ,refuge strips before planting and during the summer. 5During summer, as new carabids emerged and insecticide toxicity declined, the presence of refuge strips influenced carabids in the adjacent crop area. Carabid activity density within crop areas previously treated with insecticide was significantly higher when adjacent to refuge strips. Also, carabid communities within insecticide-treated crop areas were affected by the presence or absence of a refuge strip. 6The presence of refuge strips did not consistently augment carabid numbers in crop areas where insecticide was not applied. One explanation may be that insecticides decreased the quality of crop habitat to carabids by depletion of prey and direct mortality. However, subsequent rebounds in prey density and the absence of competing predators may make these areas relatively more attractive than unperturbed crop habitats to carabid colonization from refuges. 7This study demonstrates that refuges may buffer the negative consequences of insecticide application on carabids in adjacent fields. Diversifying agro-ecosystems with refuge habitats may be a viable strategy for maintaining carabid populations in disturbed agricultural landscapes to keep pests below outbreak levels. [source] Capitalism, Unfree Labor and Colonial Doxa: The Master and Servant Act from Britain to Hong Kong, 1823,1932JOURNAL OF HISTORICAL SOCIOLOGY, Issue 2 2010WAI KIT CHOI The Master and Servant Act was a law that allowed the use of penal sanction against workers for breach of contract in nineteenth century Britain. For scholars who believe that wage laborers under capitalism are free from "extra-economic" coercion, this law was an anomaly. One explanation suggests technological backwardness during the early stages of capitalism as the cause. In this paper I will challenge this account and offer an alternative explanation. As the British Empire expanded, the same law was enacted in many British colonies. If it was the process of capitalist production that rendered the Master and Servant Act necessary, this explanation should also apply to the British colonies. By focusing on Hong Kong, I show that this was not the case. Instead, I show that the use of judiciary coercion could be explained by Bourdieu's notions of doxa, habitus and field. [source] Effects of Chronic Oestrogen Replacement on Stress-Induced Activation of Hypothalamic-Pituitary-Adrenal Axis Control PathwaysJOURNAL OF NEUROENDOCRINOLOGY, Issue 8 2000C. V. Dayas Abstract Oestrogen replacement therapy reportedly suppresses hypothalamic-pituitary-adrenal (HPA) axis responses to an emotional stressor in postmenopausal women. However, most studies in the rat suggest a facilitatory role for oestrogen in the control of HPA axis function. One explanation for this difference may be the regimen of oestrogen replacement: during oestrogen replacement therapy, oestrogen levels are low and constant whereas most animal studies examined the HPA axis response when oestrogen levels are rising. In the present study, we assessed HPA axis stress responses in mature ovariectomized rats after plasma oestrogen levels had been maintained at physiological levels for a prolonged period (25 or 100 pg/ml for 7 days). In the case of both an emotional stressor (noise) and a physical stressor (immune challenge by systemic interleukin-1, administration), oestrogen replacement suppressed stress-related Fos-like immunolabelling, in hypothalamic neuroendocrine cells and plasma adrenocorticotropin hormone responses. From the present data, and past reports, it appears unlikely that these effects of oestrogen are due to a direct action on corticotropin-releasing factor or oxytocin cells. Therefore, to obtain some indication of oestrogen's possible site(s) of action, Fos-like immunolabelling was mapped in the amygdala and in brainstem catecholamine groups, which are neuronal populations demonstrating substantial evidence of involvement in the generation of HPA axis stress responses. In the amygdala, oestrogen replacement suppressed central nucleus responses to immune challenge, but not to noise. Amongst catecholamine cells, oestrogen replacement was more effective against responses to noise than immune challenge, suppressing A1 and A2 (noradrenergic) and C2 (adrenergic) responses to noise, but only A1 responses to immune challenge. These data suggest that, as in postmenopausal women on oestrogen replacement therapy, chronic low-level oestrogen replacement can suppress HPA axis stress responses in the rat. Moreover, oestrogen appears to exert effects at multiple sites within putative HPA axis control pathways, even though most of the relevant neuronal populations do not contain genomic receptors for this gonadal steroid and the pattern of oestrogen action differs for an emotional vs a physical stressor. [source] Value choices and considerations when limiting intensive care treatment: a qualitative studyACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 1 2009K. HALVORSEN Background: To shed light on the values and considerations that affect the decision-making processes and the decisions to limit intensive care treatment. Method: Qualitative methodology with participant observation and in-depth interviews, with an emphasis on eliciting the underlying rationale of the clinicians' actions and choices when limiting treatment. Results: Informants perceived over-treatment in intensive care medicine as a dilemma. One explanation was that the decision-making base was somewhat uncertain, complex and difficult. The informants claimed that those responsible for taking decisions from the admitting ward prolonged futile treatment because they may bear guilt or responsibility for something that had gone wrong during the course of treatment. The assessments of the patient's situation made by physicians from the admitting ward were often more organ-oriented and the expectations were less realistic than those of clinicians in the intensive care unit who frequently had a more balanced and overall perspective. Aspects such as the personality and the speciality of those involved, the culture of the unit and the degree of interdisciplinary cooperation were important issues in the decision-making processes. Conclusion: Under-communicated considerations jeopardise the principle of equal treatment. If intensive care patients are to be ensured equal treatment, strategies for interdisciplinary, transparent and appropriate decision-making processes must be developed in which open and hidden values are rendered visible, power structures disclosed, employees respected and the various perspectives of the treatment given their legitimate place. [source] Extinction debt in fragmented grasslands: paid or not?JOURNAL OF VEGETATION SCIENCE, Issue 1 2009Sara A.O. Cousins Abstract Fragmentation of grasslands and forests is considered a major threat to biodiversity. In the case of plants, the effect of fragmentation or landscape context is still unclear and published results are divergent. One explanation for this divergence is the slow response of long-lived plants, creating an extinction debt. However, this has not been empirically confirmed. In this study, data were compiled from broad-scale studies of grasslands from throughout the world that relate plant diversity to fragmentation effects. Only seven studies from northern Europe, out of a total 61, gave any information on actual habitat fragmentation in time and space. In landscapes with >10% grassland remaining, present-day species richness was related to past landscape or habitat pattern. In landscapes with <10% grassland remaining, in contrast, plant species richness was more related to contemporary landscape or habitat pattern. Studies from landscapes with >10% grassland remaining supported the concept of an extinction debt, while studies from more fragmented landscapes did not provide any evidence of an extinction debt. In order to make generalisations about historical legacies on species diversity in grasslands it is important to consider a range of highly transformed landscapes, and not only landscapes with a high amount of grassland remaining. [source] Towards valid measures of self-directed clinical learningMEDICAL EDUCATION, Issue 11 2003Tim Dornan Aim, To compare the validity of different measures of self-directed clinical learning. Methods, We used a quasi-experimental study design. The measures were: (1) a 23-item quantitative instrument measuring satisfaction with the learning process and environment; (2) free text responses to 2 open questions about the quality of students' learning experiences; (3) a quantitative, self-report measure of real patient learning, and (4) objective structured clinical examination (OSCE) and progress test results. Thirty-three students attached to a single firm during 1 curriculum year in Phase 2 of a problem-based medical curriculum formed an experimental group. Thirty-one students attached to the same firm in the previous year served as historical controls and 33 students attached to other firms within the same module served as contemporary controls. After the historical control period, experimental group students were exposed to a complex curriculum intervention that set out to maximise appropriate real patient learning through increased use of the outpatient setting, briefing and supported, reflective debriefing. Results, The quantitative satisfaction instrument was insensitive to the intervention. In contrast, the qualitative measure recorded a significantly increased number of positive statements about the appropriateness of real patient learning. Moreover, the quantitative self-report measure of real patient learning found high levels of appropriate learning activity. Regarding outpatient learning, the qualitative and quantitative real patient learning instruments were again concordant and changed in the expected direction, whereas the satisfaction measure did not. An incidental finding was that, despite all attempts to achieve horizontal integration through simultaneously providing community attachments and opening up the hospital for self-directed clinical learning, real patient learning was strongly bounded by the specialty interest of the hospital firm to which students were attached. Assessment results did not correlate with real patient learning. Conclusions, Both free text responses and students' quantitative self-reports of real patient learning were more valid than a satisfaction instrument. One explanation is that students had no benchmark against which to rate their satisfaction and curriculum change altered their tacit benchmarks. Perhaps the stronger emphasis on self-directed learning demanded more of students and dissatisfied those who were less self-directed. Results of objective, standardised assessments were not sensitive to the level of self-directed, real patient learning. Despite an integrated curriculum design that set out to override disciplinary boundaries, students' learning remained strongly influenced by the specialty of their hospital firm. [source] Determining the possible building blocks of the Earth and MarsMETEORITICS & PLANETARY SCIENCE, Issue 5 2004Thomas H. Burbine Only a very small percentage of the combinations match the oxygen isotopic composition, the assumed bulk FeO concentration, and the assumed Fe/Al weight ratio for the Earth. Since chondrites are enriched in silicon relative to estimates of the bulk Earth, none of the combinations fall near the terrestrial magmatic fractionation trend line in Mg/Si-Al/Si space. More combinations match the oxygen isotopic composition and the assumed bulk FeO concentration for Mars. These combinations fall near the trend for shergottite meteorites in Mg/Si-Al/Si space. One explanation for the difficulty in forming Earth out of known chondrites is that the Earth may be composed predominately of material that did not survive to the present day as meteorites. Another explanation could be that significant amounts of silicon are sequestered in the core and/or lower mantle of the Earth. [source] Is There a Natural Rate of Crime?AMERICAN JOURNAL OF ECONOMICS AND SOCIOLOGY, Issue 2 2010Paresh Kumar Narayan Studies in the economics of crime literature have reached mixed conclusions on the deterrence hypothesis. One explanation that has been offered for the failure to find evidence of a deterrent effect in the long run is the natural rate of crime. This article applies univariate unit root tests to crime series for the United Kingdom and United States and panel unit roots to crime rates for a panel of G7 countries to examine whether there is a natural rate of crime. Our main finding is that when we allow for two structural breaks in the univariate unit root test and a structural break in the panel data unit root test, there is strong evidence of a natural rate of crime. The policy implications of our findings is that governments should focus on altering the economic and social structural profile that determines crime in the long run rather than increasing expenditure on law enforcement that will at best reduce crime rates in the short run. [source] THE REAL EXCHANGE RATE AND THE BALASSA,SAMUELSON EFFECT: THE ROLE OF THE DISTRIBUTION SECTORPACIFIC ECONOMIC REVIEW, Issue 1 2005Ronald MacDonald The main result is that an increase in the productivity and product market competition of the distribution sector with respect to foreign countries leads to an appreciation of the real exchange rate, similar to what a relative increase in the domestic productivity of tradables does. This contrasts with the result that one would expect by considering the distribution sector as belonging to the non-tradable sector. One explanation may lie in the use of the services from the distribution sector in the tradable sector. [source] Selection in utero: A biological response to mass layoffsAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 3 2010Ralph Catalano Most research describing the biological response to unemployment appears appropriately motivated by clinical or public health concerns and focuses on death, disease, and medical care. We argue that expanding the work to include other outcomes could contribute to basic science. As an example, we use the response to mass layoffs to discriminate between two explanations of low ratios of male to female live births in stressed populations. One explanation asserts that ambient stressors reduce the ratio of males to females conceived. The other argues that the maternal stress response selects against males in utero. We show that selection in utero better explains the observed data. We conclude that human adaptation to the economic environment deserves scrutiny from a wider array of scientists than it now receives. Am. J. Hum. Biol., 2010. © 2009 Wiley-Liss, Inc. [source] Realized kernels in practice: trades and quotesTHE ECONOMETRICS JOURNAL, Issue 3 2009O. E. Barndorff-Nielsen Summary, Realized kernels use high-frequency data to estimate daily volatility of individual stock prices. They can be applied to either trade or quote data. Here we provide the details of how we suggest implementing them in practice. We compare the estimates based on trade and quote data for the same stock and find a remarkable level of agreement. We identify some features of the high-frequency data, which are challenging for realized kernels. They are when there are local trends in the data, over periods of around 10 minutes, where the prices and quotes are driven up or down. These can be associated with high volumes. One explanation for this is that they are due to non-trivial liquidity effects. [source] An interruption in unconscious communication in the analytic coupleTHE INTERNATIONAL JOURNAL OF PSYCHOANALYSIS, Issue 1 2010Hilda María Feuerhake The authors describe an interruption in communication in the analyses of two patients, which gradually brings the analytic process to a halt/standstill. They propose several hypotheses for understanding this situation. One explanation is mutual identification of primitive superegos in the analytic couple which generates a moralizing effect thereby hindering investigation and discovery. They emphasize the importance of countertransference involvement which partly provokes this particular type of impasse. They also suggest the idea of shared acting out, with complementary participations of analyst and patient. In this way the analytic couple supports a ,bastion' which protects against the risk of breaking the omnipotence of patient and analyst or contributes to this omnipotence. Their shared unconscious phantasy feeds collusion linked to unconscious persecutory guilt. The authors also describe movements to break free from this impasse. The enclave created by the analytic couple is detected and subsequently worked through by way of the patient's contribution of dream material and the analyst's work with her countertransference. [source] Factors affecting fecal glucocorticoid levels in semi-free-ranging female mandrills (Mandrillus sphinx)AMERICAN JOURNAL OF PRIMATOLOGY, Issue 11 2008Joanna M Setchell Abstract Subordinate female cercopithecine primates often experience decreased reproductive success in comparison with high-ranking females, with a later age at sexual maturity and first reproduction and/or longer interbirth intervals. One explanation that has traditionally been advanced to explain this is high levels of chronic social stress in subordinates, resulting from agonistic and aggressive interactions and leading to higher basal levels of glucocorticoids. We assessed the relationships among fecal cortisol levels and reproductive condition, dominance rank, degree of social support, and fertility in female mandrills (Mandrillus sphinx) living in a semi-free-ranging colony in Franceville, Gabon. Lower-ranking females in this colony have a reproductive disadvantage relative to higher-ranking females, and we were interested in determining whether this relationship between dominance rank and reproductive success is mediated through stress hormones. We analyzed 340 fecal samples from 19 females, collected over a 14-month period. We found that pregnant females experienced higher fecal cortisol levels than cycling or lactating females. This is similar to results for other primate species and is likely owing to increased metabolic demands and interactions between the hypothalamus,pituitary,adrenal axis, estrogen, and placental production of corticotrophin releasing hormones during pregnancy. There was no influence of dominance rank on fecal cortisol levels, suggesting that subordinate females do not suffer chronic stress. This may be because female mandrills have a stable social hierarchy, with low levels of aggression and high social support. However, we found no relationship between matriline size, as a measure of social support, and fecal cortisol levels. Subordinates may be able to avoid aggression from dominants in the large enclosure or may react only transiently to specific aggressive events, rather than continuously expecting them. Finally, we found no relationship between fecal cortisol levels and fertility. There was no difference in fecal cortisol levels between conceptive and nonconceptive cycles, and no significant relationship between fecal cortisol level and either the length of postpartum amenorrhea or the number of cycles before conception. This suggests that the influence of dominance rank on female reproductive success in this population is not mediated through chronic stress in subordinate females, and that alternative explanations of the relationship between social rank and reproduction should be sought. Am. J. Primatol. 70:1023,1032, 2008. © 2008 Wiley-Liss, Inc. [source] Gadolinium inhibits group III but not group IV muscle afferent responses to dynamic exerciseTHE JOURNAL OF PHYSIOLOGY, Issue 4 2009Shawn G. Hayes Dynamic exercise has been shown to stimulate rapidly both group III and IV muscle afferents. The often rapid (i.e. 2 s) onset latencies of the group IV afferents is particularly surprising because these unmyelinated afferents are thought to respond to the gradual accumulation of metabolites signalling a mismatch between blood/oxygen demand and supply in exercising muscles. One explanation for the rapid onset to exercise by group IV afferents is that they are mechanosensitive, a concept that has been supported by the finding that these afferents were stimulated by vasodilatation induced by injection of vasoactive drugs. We therefore examined in decerebrated cats the effect of gadolinium, a blocker of mechanogated channels, on the responses of group III and IV muscle afferents to dynamic exercise induced by electrical stimulation of the mesencephalic locomotor region. We found that gadolinium (10 mm; 1 ml) injected into the abdominal aorta had no significant effect (P > 0.05) on the responses of 11 group IV afferents to dynamic exercise. In contrast, gadolinium markedly attenuated the responses of 11 group III afferents to exercise (P < 0.05). Our findings suggest that group IV afferents are not responding to a mechanical stimulus during exercise. Instead their rapid response to dynamic exercise might be caused by a chemical substance whose concentration is directly proportional to blood flow, which increases in the skeletal muscles when they are dynamically exercising. [source] Characterization of a new xyloglucan endotransglucosylase/hydrolase (XTH) from ripening tomato fruit and implications for the diverse modes of enzymic actionTHE PLANT JOURNAL, Issue 2 2006Montserrat Saladié Summary Xyloglucan endotransglucosylase/hydrolases (XTHs) are cell wall-modifying enzymes that align within three or four distinct phylogenetic subgroups. One explanation for this grouping is association with different enzymic modes of action, as XTHs can have xyloglucan endotransglucosylase (XET) or endohydrolase (XEH) activities. While Group 1 and 2 XTHs predominantly exhibit XET activity, to date the activity of only one member of Group 3 has been reported: nasturtium TmXH1, which has a highly specialized function and hydrolyses seed-storage xyloglucan rather than modifying cell wall structure. Tomato fruit ripening was selected as a model to test the hypothesis that preferential XEH activity might be a defining characteristic of Group 3 XTHs, which would be expressed during processes where net xyloglucan depolymerization occurs. Database searches identified 25 tomato XTHs, and one gene (SlXTH5) was of particular interest as it aligned within Group 3 and was expressed abundantly during ripening. Recombinant SlXTH5 protein acted primarily as a transglucosylase in vitro and depolymerized xyloglucan more rapidly in the presence than in the absence of xyloglucan oligosaccharides (XGOs), indicative of XET activity. Thus, there is no correlation between the XTH phylogenetic grouping and the preferential enzymic activities (XET or XEH) of the proteins in those groups. Similar analyses of SlXTH2, a Group 2 tomato XTH, and nasturtium seed TmXTH1 revealed a spectrum of modes of action, suggesting that all XTHs have the capacity to function in both modes. The biomechanical properties of plant walls were unaffected by incubation with SlXTH5, with or without XGOs, suggesting that XTHs do not represent primary cell wall-loosening agents. The possible roles of SlXTH5 in vivo are discussed. [source] Hen harrier foraging success in relation to land use in ScotlandANIMAL CONSERVATION, Issue 2 2002Steve Redpath In the UK, hen harriers (Circus cyaneus) are illegally killed on moorland that is managed for red grouse (Lagopus lagopus scoticus), and they produce fewer young per female on grouse moorland than on either unmanaged moorland or forestry. However, those breeding attempts on grouse moorland that escape nest destruction produce more young than in other land-use classes. One explanation for this difference is that food is more available to harriers on managed moorland than elsewhere. To examine this hypothesis, we compared the capture rates of hunting male harriers on sites across Scotland. Four of these sites were managed for grouse whilst the remaining three consisted of either unmanaged moorland or a mixture of unmanaged moorland and young forestry plantations. We found a significant difference in capture rates, with harriers on managed grouse moorland capturing prey at a greater rate than elsewhere, supporting the idea that prey were more available on grouse moorland. However, there was no difference in strike rates between the land-use classes, suggesting that prey were not necessarily more abundant on grouse moors. Males on unmanaged moorland tended to catch larger prey, though this was insufficient to compensate fully for the reduced capture rates. The improved hunting success on grouse moorland means that this habitat is likely to be more attractive to breeding harriers, thereby increasing the conflict between those interested in maximizing grouse numbers and those interested in conserving rare raptors. [source] When goals constrain: Eye movements and memory for goal-Oriented map studyAPPLIED COGNITIVE PSYCHOLOGY, Issue 6 2009Tad T. Brunyé Perspective goals, such as studying a map to learn a route through an environment or the overall layout of an environment, produce memory congruent with the goal-directed rather than the studied perspective. One explanation for this finding is that perspective goals guide attention towards actively gathering relevant information during learning. A second explanation is that information is automatically organized into a goal-congruent spatial model that guides retrieval. Both explanations predict goal-congruent memory, but only the former one predicts eye movement differences during study. The present experiment investigated the effect of perspective goals on eye movement during map study and the flexibility of resulting spatial memories. Results demonstrate eye movements towards goal-congruent map elements during learning, and lasting memory effects at test. These findings carry implications for the design of adaptive hand-held and in-vehicle navigation interfaces that accommodate for varied user goals. Copyright © 2008 John Wiley & Sons, Ltd. [source] The evolution of cluster early-type galaxies over the past 8 GyrASTRONOMISCHE NACHRICHTEN, Issue 9-10 2009A. Fritz Abstract We present the Fundamental Plane (FP) of early-type galaxies in the clusters of galaxies RXJ1415.1+3612 at z = 1.013. This is the first detailed FP investigation of cluster early-type galaxies at redshift z = 1. The distant cluster galaxies follow a steeper FP relation compared to the local FP. The change in the slope of the FP can be interpreted as a massdependent evolution. To analyse in more detail the galaxy population in high redshift galaxy clusters at 0.8 < z < 1, we combine our sample with a previous detailed spectroscopic study of 38 early-type galaxies in two distant galaxy clusters, RXJ0152.7,1357 at z = 0.83 and RXJ1226.9+3332 at z = 0.89. For all clusters Gemini/GMOS spectroscopy with high signal-to-noise and intermediate-resolution has been acquired to measure the internal kinematics and stellar populations of the galaxies. From HST/ACS imaging, surface brightness profiles, morphologies and structural parameters were derived for the galaxy sample. The least massive galaxies (M = 2 x 1010 M,) in our sample have experienced their most recent major star formation burst at zform , 1.1. For massive galaxies (M > 2 x 1011 M,) the bulk of their stellar populations have been formed earlier zform , 1.6. Our results confirm previous findings by Jørgensen et al. This suggests that the less massive galaxies in the distant clusters have much younger stellar populations than their more massive counterparts. One explanation is that low-mass cluster galaxies have experienced more extended star formation histories with more frequent bursts of star formation with shorter duration compared to the formation history of high-mass cluster galaxies (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The destruction of cometary grains and changes in the luminosity of cometsASTRONOMISCHE NACHRICHTEN, Issue 8 2009P. Gronkowski Abstract One explanation of the sudden changes in the brightness of comets is proposed based on the author's earlier suggestions involving the fragmentation of cometary grains. Within the inner coma, a core-mantle model of the structure of grains is assumed. The proposed mechanism is a combination of electrostatic stress and thermodynamical fragmentation of the cometary grains water-ice mantle. It has been shown that the vapour pressure of volatile inclusions placed in the waterice mantle of grains can increase sufficiently to cause their fragmentation. It takes place before grains can completely sublime into the vacuum away. Numerical calculations have been carried out for a large range of values of probable physical characteristics of cometary material. The proposed approach yields increases in cometary brightness consistent with observations of typical cometary outbursts. It is concluded that this approach can provide an explanation of the sudden change in activity of comets for a wide range of heliocentric distances (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Leadership and Effectiveness in the Context of Gender: The Role of Leaders' Verbal Behaviour,BRITISH JOURNAL OF MANAGEMENT, Issue 1 2008Gisela Mohr This field study focuses on verbal consideration, which is a leadership behaviour that expresses esteem for the follower and her or his work, knowledge and opinion. It was assumed that the relationship between verbal consideration and various outcomes is moderated by the leader's gender. One-hundred-and-forty leaders and 455 of their direct followers were surveyed in a one-wave questionnaire study in Germany. Male and female leaders showed the same degree of verbal consideration as rated by their followers. Verbal consideration is related to three out of four outcome variables for both sexes. One unexpected moderating effect of leaders' gender was found: followers of male leaders displaying verbal consideration report less ,irritation' (a state of exhaustion considered a threat to good task fulfilment). One explanation may be that male leaders get ,extra credit' for showing verbal consideration as it may be thought to entail special effort, whereas for female leaders it may be seen as normal and routine. This assumption should be examined in further studies in order to get more information about the different mechanisms by which female and male leaders reach the same quality of outcomes. [source] Adolescent smoking and depression: evidence for self-medication and peer smoking mediationADDICTION, Issue 10 2009Janet Audrain-McGovern ABSTRACT Aims The nature of the relationship between adolescent smoking and depression is unclear and the mechanisms that account for the comorbidity have received little investigation. The present study sought to clarify the temporal precedence for smoking and depression and to determine whether these variables are linked indirectly through peer smoking. Participants The sample was composed of 1093 adolescents participating in a longitudinal study of the behavioral predictors of smoking adoption. Design and measurements In this prospective cohort study, smoking, depression, peer smoking and other covariates were measured annually from mid-adolescence (9th grade; age 14) to late adolescence (12th grade, age 18). Findings Parallel processes latent growth curve models supported a bidirectional relationship between adolescent smoking and depression, where higher depression symptoms in mid-adolescence (age 14) predicted adolescent smoking progression from mid- to late adolescence (ages 14,18). A significant indirect effect indicated that higher depression symptoms across time predicted an increase in the number of smoking peers, which in turn predicted smoking progression from mid-adolescence to late adolescence. In addition, smoking progression predicted a deceleration of depression symptoms from mid- to late adolescence. A significant indirect effect indicated that greater smoking at baseline predicted a deceleration in the number of smoking peers across time, which predicted a deceleration in depression symptoms from mid-adolescence to late adolescence. Conclusions The current study provides the first evidence of bidirectional self-medication processes in the relationship between adolescent smoking and depression and highlights peer smoking as one explanation for the comorbidity. [source] | |||||||||||||||||||||||||||||||||||||