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Persistence
Kinds of Persistence Terms modified by Persistence Selected AbstractsTwin deficits: squaring theory, evidence and common senseECONOMIC POLICY, Issue 48 2006Giancarlo Corsetti SUMMARY Budget deficits and current accounts OPENNESS AND FISCAL PERSISTENCE Simple accounting suggests that shocks to the government budget move the current account in the same direction, and this ,twin deficits' intuition leads many observers to call for fiscal consolidation in the US as a necessary measure to reduce the large external imbalance of this country. The response of other macroeconomic variables to budget developments, however, has important implications for ,twin deficits' and for this policy prescription. Focusing on the international transmission of fiscal policy shocks via terms of trade changes, we show that the likelihood and magnitude of twin deficits increases with the degree of openness of an economy, and decreases with the persistence of fiscal shocks. We take this insight to the data and investigate the transmission of fiscal shocks in a vector autoregression (VAR) model estimated for Australia, Canada, the UK and the US. We find that in less open countries the external impact of shocks to either government spending or budget deficits is limited, while private investment responds in line with our theoretical prediction. These results suggest that a fiscal retrenchment in the US may have a limited impact on its current external deficit. , Giancarlo Corsetti and Gernot J. Müller [source] BEARING WITNESS: TOBACCO, PUBLIC HEALTH AND HISTORY THE CIGARETTE CENTURY: THE RISE, FALL AND DEADLY PERSISTENCE OF THE PRODUCT THAT DEFINED AMERICA.ADDICTION, Issue 7 20092000., Edited by A.M. Brandt MARKETING HEALTH: SMOKING AND THE DISCOURSE OF PUBLIC HEALTH IN BRITAIN First page of article [source] EFFECTS OF APPLICATION PARAMETERS AND ADJUVANTS ON THE FOLIAR SURVIVAL AND PERSISTENCE OF ENTOMOPATHOGENIC NEMATODE STEINERNEMA CARPOCAPSAE ALL STRAIN ON CABBAGESINSECT SCIENCE, Issue 2 2004Yong-ling Jin Abstract, Effects of the critical parameters (spray pressure, the distance between a sprayer and the sprayed plant, the concentration of infective juveniles (Us), volumes of the sprayed suspension of IJs, the temperature and humidity combinations) and the addition of various adjuvants on the survival and persistence of entomopathogenic nematode Steinernema carpocapsae All strain on leaf surfaces of the Chinese cabbage Brassica pekingensis were determined. The results showed that (1) The pressure of a sprayer had negative influence on the persistence of IJs on the leaf. (2) The numbers of the living IJs collected on the leaf significantly increased with the IJ dosages applied on the leaf when the dosage was over 2 000 IJs per mL. (3) More IJs (from 10.1 IJs/cm2 to 45.5 IJs/cm2) were collected on the leaf when more volumes of IJ suspension (from 3.3 mL to 19.8 mL) were sprayed. However, when the highest volume of IJ suspension was used, the IJ numbers collected did not increase. (4) In general, the survival of the IJs on the leaf decreased with the exposure time. (5) The formulation of IJs by adding xanthan gum, a sticker and detergent surfactant enhanced the survival and persistence of IJs. The number of living IJs on the leaf with 0.3 % of xanthan gum was 150 times higher than that of the IJs with water alone. IJ suspensions with different concentrations of glycerin and with 0.5 % molasses and 0.01 % detergent surfactant showed similar effects. [source] TESTING LONG-HORIZON PREDICTIVE ABILITY WITH HIGH PERSISTENCE, AND THE MEESE,ROGOFF PUZZLE*INTERNATIONAL ECONOMIC REVIEW, Issue 1 2005Barbara Rossi A well-known puzzle in international finance is that a random walk predicts exchange rates better than economic models. I offer a potential explanation. When exchange rates and fundamentals are highly persistent, long-horizon forecasts of economic models are biased by the estimation error. When this bias is big, a random walk will forecast better, even if the economic model is true. I propose a test for equal predictability in the presence of high persistence. It shows that the poor forecasting ability of economic models does not imply that the models are not good descriptions of the data. [source] POSITIVE FEEDBACK AND THE DEVELOPMENT AND PERSISTENCE OF ECOSYSTEM DISRUPTIVE ALGAL BLOOMS,JOURNAL OF PHYCOLOGY, Issue 5 2006William G. Sunda Harmful algal blooms (HABs) have occurred with increasing frequency in recent years with eutrophication and other anthropogenic alterations of coastal ecosystems. Many of these blooms severely alter or degrade ecosystem function, and are referred to here as ecosystem disruptive algal blooms (EDABs). These blooms are often caused by toxic or unpalatable species that decrease grazing rates by planktonic and benthic herbivores, and thereby disrupt the transfer of nutrients and energy to higher trophic levels, and decrease nutrient recycling. Many factors, such as nutrient availability and herbivore grazing have been proposed to separately influence EDAB dynamics, but interactions among these factors have rarely been considered. Here we discuss positive feedback interactions among nutrient availability, herbivore grazing, and nutrient regeneration, which have the potential to substantially influence the dynamics of EDAB events. The positive feedbacks result from a reduction of grazing rates on EDAB species caused by toxicity or unpalatability of these algae, which promotes the proliferation of the EDAB species. The decreased rates also lower grazer-mediated recycling of nutrients and thereby decrease nutrient availability. Since many EDAB species are well-adapted to nutrient-stressed environments and many exhibit increased toxin production and toxicity under nutrient limitation, positive feedbacks are established which can greatly increase the rate of bloom development and the adverse effects on the ecosystem. An understanding of how these feedbacks interact with other regulating factors, such as benthic/pelagic nutrient coupling, physical forcing, and life cycles of EDAB species provides a substantial future challenge. [source] EFFECTS OF DOMAIN SIZE ON THE PERSISTENCE OF POPULATIONS IN A DIFFUSIVE FOOD-CHAIN MODEL WITH BEDDINGTON-DeANGELIS FUNCTIONAL RESPONSENATURAL RESOURCE MODELING, Issue 3 2001ROBERT STEPHEN CANTRELL ABSTRACT. A food chain consisting of species at three trophic levels is modeled using Beddington-DeAngelis functional responses as the links between trophic levels. The dispersal of the species is modeled by diffusion, so the resulting model is a three component reaction-diffusion system. The behavior of the system is described in terms of predictions of extinction or persistence of the species. Persistence is characterized via permanence, i.e., uniform persistence plus dissi-pativity. The way that the predictions of extinction or persistence depend on domain size is studied by examining how they vary as the size (but not the shape) of the underlying spatial domain is changed. [source] CANDIDATE PERSISTENCE AND PERSONALITY TEST PRACTICE EFFECTS: IMPLICATIONS FOR STAFFING SYSTEM MANAGEMENTPERSONNEL PSYCHOLOGY, Issue 2 2010JOHN P. HAUSKNECHT Candidates persist in selection settings for numerous reasons, prompting several concerns regarding staffing-system management. Predictors of the propensity to retest and personality test practice effects were investigated among a sample of 15,338 candidates who applied for supervisory positions (and 357 who repeated the selection process) over a 4-year period with a large organization in the service industry. Results reveal greater likelihood of retesting among internal candidates and overall evidence of small-to-moderate personality test practice effects. Compared to passing candidates who retested for various reasons, failing candidates pursued alternative response strategies upon retesting and generated dimension-level practice effects that reached .40 to .60, whereas passing candidates generally replicated their initial profiles. For several subscales, low initial scores were associated with practice effects that exceeded a full standard deviation. Implications for research, practice, and policy are discussed. [source] RISK, PERSISTENCE and FOCUS: A LIFE CYCLE OF THE ENTREPRENEURAUSTRALIAN ECONOMIC HISTORY REVIEW, Issue 3 2005Ian Hunter Business lifecycle; business failure; entrepreneurship; New Zealand; colonisation Adapting a life cycle model from managerial literature, conclusions are drawn about the nature of colonial entrepreneurship from a case analysis of 133 New Zealand entrepreneurs, active between 1880 and 1910. Five stages in the life cycle of the entrepreneur are investigated: preparation, embarkation, exploration, expansion and transformation. Characteristic behaviours observed include the prevalence of entrepreneurial partnerships; a propensity for commencing multiple business ventures; and persistence in the face of business failure. Strategically, the colonial entrepreneur leveraged personal skills and abilities as a modus operandi for business expansion, often relying on family ownership and family management structures. [source] A Primer on Topological PersistenceCOMPUTER GRAPHICS FORUM, Issue 3 2006Herbert Edelsbrunner The idea of topological persistence is to look at homological features that persist along a nested sequence of topo-logical spaces. As a typical example, we may take the sequence of sublevel sets of a function. The combinatorial characterization of persistence in terms of pairs of critical values and fast algorithms computing these pairs make this idea practical and useful in dealing with the pervasive phenomenon of noise in geometric and visual data. This talk will 1. recall the relatively short history of persistence and some of its older roots; 2. introduce the concept intuitively while pointing out where algebra is needed to solidify the more difficult steps; 3. discuss a few applications to give a feeling of the potential of the method in dealing with noise and scale. Besides the initial concept, the talk will touch upon recent extensions and their motivation. [source] Persistence of Left Supracardinal Vein in an Adult Patient with Heart,Hand Syndrome and Cardiac PacemakerCONGENITAL HEART DISEASE, Issue 3 2008Jan Nemec MD ABSTRACT A patient with a sporadic heart,hand syndrome, which includes thumb hypoplasia, septum primum atrial septal defect, and cleft mitral valve is described. During attempted placement of a pacemaker lead, persistence of left superior and inferior vena cava was found in addition to the right-sided caval veins. This corresponds to persistence of left-sided supracardinal vein present during fetal development. [source] Quantifying Plant Population Persistence in Human-Dominated LandscapesCONSERVATION BIOLOGY, Issue 4 2008DAWN M. LAWSON Base de Datos de la Diversidad Natural de California; conservación de plantas; crecimiento de la población; especies en peligro; paisajes urbanos Abstract:,We assessed population performance of rare plants across a gradient from rural to urban landscapes and evaluated 2 hypotheses central to strategic conservation planning: (1) population performance declines with increasing human dominance and (2) small populations perform poorly relative to larger ones. Assessing these hypotheses is critical to strategic conservation planning. The current conservation paradigm adheres to the well-established ecology theory that small isolated populations, particularly those in human-dominated landscapes, are the least likely to succeed over the long term. Consequently, conservation planning has strongly favored large, remote targets for protection. This shift in conservation toward ecosystem-based programs and protection of populations within large, remote systems has been at the expense of protection of the rarest of the rare species, the dominant paradigm for conservation driven by the endangered species act. Yet, avoiding conservation of small populations appears to be based more on theoretical understanding and expert opinion than empiricism. We used Natural Heritage data from California in an assessment of population performance of rare plants across a landscape with an urban-rural gradient. Population performance did not decrease in urban settings or for populations that were initially small. Our results are consistent with a pattern of few species extinctions within these landscapes over the past several decades. We conclude that these populations within compromised landscapes can contribute to overall biodiversity conservation. We further argue that conservation planning for biodiversity preservation should allocate relatively more resources to protecting urban-associated plant taxa because they may provide conservation benefit beyond simply protecting isolated populations; they may be useful in building social interest in conservation. Resumen:,Evaluamos el funcionamiento de la población de plantas raras a lo largo de un gradiente de paisajes rurales a urbanos y evaluamos 2 hipótesis centrales para la planificación estratégica de la conservación: (1) declinaciones en el funcionamiento poblacional con el incremento de la dominancia humana y (2) las poblaciones pequeñas funcionan pobremente en relación con las grandes. La evaluación de estas hipótesis es crítica para la planificación estratégica de la conservación. El paradigma actual de la conservación se adhiere a la teoría ecológica bien establecida que propone que las poblaciones pequeñas aisladas, particularmente en paisajes dominados por humanos, tienen menor probabilidad de sobrevivir a largo plazo. Consecuentemente, la planificación de la conservación ha favorecido objetivos grandes y remotos. Este cambio hacia programas de conservación basados en ecosistemas y la protección de poblaciones en sistemas extensos y remotos ha sido a costa de la protección de las especies más raras entre las raras, el paradigma dominante en la conservación conducida por el acta de especies en peligro. No obstante, la evasión de la conservación de poblaciones pequeñas parece estar basada más en entendimiento teórico y en la opinión de expertos que en el empirismo. Utilizamos datos del Patrimonio Natural de California en una evaluación del funcionamiento de plantas raras en un paisaje con un gradiente urbano a rural. El funcionamiento de la población no decreció en sitios urbanos o en poblaciones que eran pequeñas inicialmente. Nuestros resultados son consistentes con un patrón de extinción de especies en estos paisajes en las últimas décadas. Concluimos que estas poblaciones en paisajes comprometidos pueden contribuir a la conservación de la biodiversidad en general. También argumentamos que la planificación de la conservación para la preservación de la biodiversidad debería asignar más recursos para la protección de taxa de plantas asociadas a ambientes urbanos porque pueden proporcionar beneficios de conservación más allá de simplemente proteger poblaciones aisladas; pueden ser útiles para construir el interés social por la conservación. [source] Effects of Habitat Fragmentation by Damming on the Persistence of Stream-Dwelling Charr PopulationsCONSERVATION BIOLOGY, Issue 5 2002Kentaro Morita We assessed the effect of habitat fragmentation by damming on the population persistence of a stream-dwelling fish, the white-spotted charr (Salvelinus leucomaenis), in streams of southwestern Hokkaido, Japan. We sampled for charr at 52 dammed-off sites by electrofishing or snorkeling and measured five habitat characteristics: isolation period, watershed area, gradient, elevation, distance from sea. Of the 52 study sites above dams, white-spotted charr were absent at 17 sites and were present at 35 sites. Because the charr occupied all undammed upstream reaches, the damming would cause the absence of charr upstream. Among five habitat characteristics examined, stepwise logistic-regression analysis showed that disappearance was promoted with increasing isolation period, with decreasing watershed area (i.e., habitat size), and with decreasing gradient. The resulting logistic model explained 82.7% of the present white-spotted charr occurrence and forecasted that 12 of 35 extant populations will disappear after 50 years. Our findings imply that extirpation of small, dammed-off populations is inevitable unless efficient fish ladders are installed or dams are removed. Resumen: La construcción de presas tiene serias consecuencias sobre los ecosistemas acuáticos y uno de los mas serios es el "efecto de barrera" ( la prevención de que un organismo migre a través del sistema). Evaluamos los efectos de la fragmentación del hábitat ocasionados por la construcción de presas en la persistencia de un pez morador de arroyos, la trucha de montaña de manchas blancas ( Salvelinus leucomaenis), en arroyos del suroeste de Hokkaido, Japón. Muestreamos en 52 sitios con represas empleando electropesca o buceo con esnórquel y medimos cinco características del hábitat ( periodo de aislamiento, área de la cuenca, gradiente, elevación y distancia al mar). De los 52 sitios de estudio ubicados arriba de las represas las truchas de montaña estuvieron ausentes en 17 sitios y presentes en 35 sitios. Debido a que las truchas de montaña ocupaban todos los rangos sin represas arroyo arriba, la creación de represas pudo causar la ausencia de truchas de montaña arroyo arriba. Dentro de las cinco características del hábitat examinadas, el análisis de regresión logística mostró que la desaparición era promovida por un incremento en el periodo de aislamiento, con una disminución en el área de la cuenca (i.e. tamaño del hábitat) y con una disminución del gradiente. El modelo logístico resultante explicó 82.7% de la presencia de truchas de montaña y pronosticó que 12 de la 35 poblaciones actuales desaparecerían después de 50 años. Nuestros resultados implican que la extirpación es pequeña y que la exclusión por construcción de represas es inevitable a menos que se instalen desvíos para peces o que se remuevan las presas. [source] Obsessive-compulsive disorder among African Americans and blacks of Caribbean descent: results from the national survey of American life,DEPRESSION AND ANXIETY, Issue 12 2008Joseph A. Himle Ph.D. Abstract Background: There is limited research regarding the nature and prevalence of obsessive-compulsive disorder (OCD) among various racial and ethnic subpopulations within the United States, including African Americans and blacks of Caribbean descent. Although heterogeneity within the black population in the United States has largely been ignored, notable differences exist between blacks of Caribbean descent and African Americans with respect to ethnicity, national heritage, and living circumstances. This is the first comprehensive examination of OCD among African Americans and blacks of Caribbean descent. Methods: Data from the National Survey of American Life, a national household probability sample of African Americans and Caribbean blacks in the United States, were used to examine rates of OCD among these groups. Results: Lifetime and 12-month OCD prevalence estimates were very similar for African Americans and Caribbean blacks. Persistence of OCD and rates of co-occurring psychiatric disorders were very high and also similar between African American and Caribbean black respondents. Both groups had high levels of overall mental illness severity and functional impairment. Use of services was low for both groups, particularly in specialty mental health settings. Use of anti-obsessional medications was also rare, especially among the Caribbean black OCD population. Conclusions: OCD among African Americans and Caribbean blacks is very persistent, often accompanied by other psychiatric disorders, and is associated with high overall mental illness severity and functional impairment. It is also likely that very few blacks in the United States with OCD are receiving evidence-based treatment and thus considerable effort is needed to bring treatment to these groups. Depression and Anxiety, 2008. Published 2008 Wiley-Liss, Inc. [source] Persistence and Improvement of Nasolabial Fold Correction with Nonanimal-Stabilized Hyaluronic Acid 100,000 Gel Particles/mL Filler on Two Retreatment Schedules: Results up to 18 Months on Two Retreatment SchedulesDERMATOLOGIC SURGERY, Issue 2008RHODA S. NARINS MD BACKGROUND Nonanimal-stabilized hyaluronic acid (NASHA) fillers are frequently used for facial soft tissue augmentation. Their long-term efficacy and the effects of different retreatment schedules are not well established. OBJECTIVE This is an 18-month interim analysis of a 30-month study to evaluate the efficacy and persistence of NASHA 100,000 gel particles/mL filler with two different retreatment schedules. METHODS This multicenter, randomized, evaluator-blinded study enrolled 75 patients with moderate to severe nasolabial folds. Patients were randomized to retreatment of one nasolabial fold at 4.5 months and the contralateral fold at 9 months after correction of both folds at the initial visit. RESULTS Wrinkle Severity Rating Scale scores improved significantly (p<.001) from baseline, with mean improvements ranging from 1.1 to 1.7 grades. Almost all patients (97%) responded satisfactorily, and the efficacy of the retreatment schedules did not differ significantly. Adverse events, primarily swelling and bruising, occurred in 33% of patients; none were serious. CONCLUSION The improvements seen after initial treatment with NASHA 100,000 gel particles/mL filler persisted for up to 18 months with one retreatment. The response was equivalent for retreatment at 4.5 and 9 months. [source] Persistence of road runoff generation in a logged catchment in Peninsular MalaysiaEARTH SURFACE PROCESSES AND LANDFORMS, Issue 13 2007Alan D. Ziegler Abstract Measurements of saturated hydraulic conductivity (Ks) and diagnostic model simulations show that all types of logging road/trail in the 14·4 ha Bukit Tarek Experimental Catchment 3 (BTEC3) generate substantial Horton overland flow (HOF) during most storms, regardless of design and level of trafficking. Near-surface Ks(0,0·05 m) on the main logging road, skid trails and newly constructed logging terraces was less than 1, 2 and 34 mm h,1, respectively. Near-surface Ks on an abandoned skid trail in an adjacent basin was higher (62 mm h,1), owing to the development of a thin organic-rich layer on the running surface over the past 40 years. Saturated hydraulic conductivity measured at 0·25 m below the surface of all roads was not different (all <6 mm h,1) and corresponded to the Ks of the adjacent hillslope subsoil, as most roads were excavated into the regolith more than 0·5,1 m. After 40 years, only limited recovery in near-surface Ks occurred on the abandoned skid trail. This road generated HOF after the storage capacity of the upper near-surface layer was exceeded during events larger than about 20 mm. Thus, excavation into low- Ks substrate had a greater influence on the persistence of surface runoff production than did surface compaction by machinery during construction and subsequent use during logging operations. Overland flow on BTEC3 roads was also augmented by the interception of shallow subsurface flow traveling along the soil,saprolite/bedrock interface and return flow emerging from the cutbank through shallow biogenic pipes. The most feasible strategy for reducing long-term road-related impacts in BTEC3 is limiting the depth of excavation and designing a more efficient road network, including minimizing the length and connectivity of roads and skid trails. Copyright © 2007 John Wiley & Sons, Ltd. [source] Persistence of vibrios in marine bivalves: the role of interactions with haemolymph componentsENVIRONMENTAL MICROBIOLOGY, Issue 6 2005Carla Pruzzo Summary Marine bivalves are widespread in coastal environments and, due to their filter-feeding habit, they can accumulate large numbers of bacteria thus acting as passive carriers of human pathogens. Bivalves possess both humoral and cellular defence mechanisms that operate in a co-ordinated way to kill and eliminate infecting bacteria. Vibrio species are very abundant in coastal waters and are commonly isolated from edible bivalves tissues where they can persist after depuration processes in controlled waters. Such observations indicate that vibrios are regular components of bivalve microflora and that the molluscs can represent an important ecological niche for these bacteria. Here we tried to summarize data on the interactions between vibrios and bivalve haemolymph; the available evidence supports the hypothesis that persistence of bacteria in bivalve tissues depends, at least in part, on their sensitivity to the bactericidal activity of the haemolymph. Results obtained with an in vitro model of Vibrio cholerae challenged against Mytilus galloprovincialis haemocytes indicate that bacterial surface components, soluble haemolymph factors and the signalling pathways of the haemocyte host are involved in determining the result of vibrio,haemolymph interactions. [source] Persistence and degradation of maize-expressed vaccine protein, Escherichia coli heat-labile enterotoxin subunit B, in soil and water,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2008Hirofumi Kosaki Abstract Transgenic plants represent an innovative platform for the cost-effective large-scale production of various pharmaceutical proteins. The eventual open-field production of plant-made pharmaceuticals (PMPs) requires risk assessment to determine the potential for harm to the surrounding ecosystem. In the present study, the environmental persistence of a transgenic maize-expressed antigen, Escherichia coli heat-labile enterotoxin subunit B (LTB), was studied under laboratory conditions. To semiquantitatively monitor the persistence of LTB in soil, extraction with a high-salt, high-pH extraction buffer was optimized using the closely homologous Vibrio cholerae enterotoxin subunit B (CTB) as a test substance. The time to dissipation of 50% (DT50) of the extractable fraction of maize-expressed LTB was 4 to 15 d in pond water and 35 to 90 d in soils. Both extraction efficacy and persistence were strongly affected by the matrix type and incubation conditions. In contrast with maize-expressed LTB, the DT50 for bacterially produced LTB and CTB was less than 4 d both in pond water and soil. Although maize-expressed LTB was more stable than bacterially produced analogue, its dissipation was governed by an initial lag, which could be attributed to release from the plant material, followed by rapid decline. [source] Persistence of drug use during imprisonment: relationship of drug type, recency of use and severity of dependence to use of heroin, cocaine and amphetamine in prisonADDICTION, Issue 8 2006John Strang ABSTRACT Aim To investigate the persistence of use of heroin, cocaine and amphetamine drugs during imprisonment, and to identify factors associated with increased levels of persistence. Design The use of heroin, cocaine and amphetamine by current prison inmates has been examined and, in particular, the relationship between drug use within prison and the type of drug used prior to imprisonment, recency of use and severity of dependence., Setting and participants A randomly selected sample of 1009 adult male prisoners in 13 prisons in England and Wales during 1994/95; structured confidential interviews conducted by independent research staff. Enquiry about prior use of heroin, cocaine or amphetamine focused on three time-periods (ever, last year and last month pre-prison) and the use of these drugs during the first month of imprisonment. Findings A total of 557 (55%) of the 1009 prisoners had used previously one of the three drugs selected for study: 58% had used heroin, 69% cocaine and 75% amphetamine. More than half (59%; 327/557) had used these drugs in the month before the current imprisonment. Drug use in prisons was most likely to occur among those who had used in the month prior to imprisonment. The persistence of heroin use in prison occurred more frequently (70%) than use of cocaine (20%) or amphetamine (15%). Of those using heroin pre-imprisonment, 67% considered they were dependent, compared to 15% and 22%, respectively, for cocaine and amphetamine users. Conclusions Changes in the drug-taking behaviour of drug users after imprisonment vary according to the type of drug being taken. Prisoners were much more likely to continue to use heroin than either cocaine or amphetamines while in prison. Heroin was most likely to be used by those who had been using heroin during the immediate pre-imprisonment period, and particularly by the two-thirds of heroin users who considered themselves dependent. In view of the high prevalence of prior use of these drugs by individuals currently imprisoned, continuing attention is required to study of their behaviour and of the impact of interventions that may be introduced during or following their incarceration. [source] A test of the community conditioning hypothesis: Persistence of effects in model ecological structures dosed with the jet fuel jp-8ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2000Wayne G. Landis Abstract The foundation of the community conditioning hypothesis, the persistence of effects, was tested in a series of microcosm experiments. Experiments were conducted with the water-soluble fraction of the turbine fuel JP-8 using the standard protocols for the standardized aquatic microcosm (SAM). A repeat trial was conducted using the SAM protocol but with a 126-d test period, twice the standard duration. The results were examined using a variety of conventional univariate, multivariate, and graphical techniques. The principal conclusions were as follows. Effects are persistent in these model ecological systems long after the degradation of the toxicant. Patterns of impacts are detectable at concentrations 15 times lower than an experimentally derived single-species EC50. The replicate experiments are not replicable in the specific, but the broad pattern of the disruption of algal- herbivore dynamics followed by more subtle effects are consistently repeated. The durability of the indirect effects and therefore the information about historical events appears to be a consistent feature of these microcosm systems. The identity of the treatment groups persists. The critical features of the community conditioning hypothesis,persistence of information within ecologicalsystems and the reappearance of patterns and therefore the nonequilibrium dynamics,are again confirmed. The implications of these findings for environmental toxicology, monitoring, and ecological risk assessment are discussed. [source] Persistence of Alarm-Call Behaviour in the Absence of Predators: A Comparison Between Wild and Captive-Born Meerkats (Suricata Suricatta)ETHOLOGY, Issue 11 2007Linda I. Hollén Performing correct anti-predator behaviour is crucial for prey to survive. But, are such abilities lost in species or populations living in predator-free environments? How individuals respond to the loss of predators has been shown to depend on factors such as the degree to which anti-predator behaviour relies on experience, the type of cues evoking the behaviour, the cost of expressing the behaviour and the number of generations under which relaxed selection has taken place. Here we investigated whether captive-born populations of meerkats (Suricata suricatta) used the same repertoire of alarm calls previously documented in wild populations and whether captive animals, as wild ones, could recognize potential predators through olfactory cues. We found that all alarm calls that have been documented in the wild also occurred in captivity and were given in broadly similar contexts. Furthermore, without prior experience of odours from predators, captive meerkats seemed to distinguish between faeces of potential predators (carnivores) and non-predators (herbivores). Despite slight structural differences, the alarm calls given in response to the faeces largely resembled those recorded in similar contexts in the wild. These results from captive populations suggest that direct, physical interaction with predators is not necessary for meerkats to perform correct anti-predator behaviour in terms of alarm-call usage and olfactory predator recognition. Such behaviour may have been retained in captivity because relatively little experience seems necessary for correct performance in the wild and/or because of the recency of relaxed selection on these populations. [source] The Multipredator Hypothesis and the Evolutionary Persistence of Antipredator BehaviorETHOLOGY, Issue 3 2006Daniel T. Blumstein Invited Review Abstract Isolation from predators affects prey behavior, morphology, and life history, but there is tremendous variation in the time course of these responses. Previous hypotheses to explain this variation have limited predictive ability. I develop a ,multipredator' hypothesis to explain the evolutionary persistence of antipredator behavior after the loss of some, but not all, of a species' predators. The hypothesis assumes pleiotropy, whereby elements of antipredator behavior may function in non-predatory situations, and linkage, such that genes influencing the expression of antipredator behavior do not assort independently. The hypothesis is restricted to species with multiple predators (most species) and aims to predict the conditions under which antipredator behavior will persist following the loss of one or more of a species' predators. I acknowledge that the relative costs of non-functional antipredator behavior will influence the likelihood of linkage and therefore persistence. The hypothesis makes two main predictions. First, genes responsible for antipredator behavior will not be scattered throughout the genome but rather may be found close together on the same chromosome(s). Secondly, the presence of any predators may be sufficient to maintain antipredator behavior for missing predators. Advances in behavioral genetics will allow tests of the first prediction, while studies of geographic variation in antipredator behavior provide some support for the second. [source] Inverse correlation between IL-7 receptor expression and CD8 T cell exhaustion during persistent antigen stimulationEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 3 2005Abstract Persistence is a hallmark of infection by viruses such as HIV, hepatitis B virus, hepatitis C virus and LCMV. In the case of LCMV, persistence may often be associated with exhaustion of CD8+ T cells. We demonstrate here that persistent antigen suppressed IL-7R, expression and this correlated with T cell exhaustion and reduced expression of the anti-apoptotic molecule B cell leukemia/lymphoma 2 (Bcl-2). In contrast, exposure to short-lived antigen only temporarily suppressed IL-7R, expression, failed to induce T cell exhaustion, and primed T cells. Persistent antigen also suppressed IL-7R, expression on primed T cells and this correlated with exhaustion of a previously stable primed T cell population. These findings suggest that antigen longevity regulates T cell fate. [source] Persistence of Cryphonectria hypoviruses after their release for biological control of chestnut blight in West Virginia forestsFOREST PATHOLOGY, Issue 6 2002Y.-C. Liu Summary Although Cryphonectria hypoviruses have been relatively successful as biological control agents of chestnut blight in Europe, their success in North America has been limited. Experimental releases of hypoviruses were made in 1978,82 at two sites in West Virginia forests with high densities of regenerating chestnut trees. Cryphonectria hypovirus 1 (CHV-1) from Europe, as well as American isolates of Cryphonectria parasitica containing CHV-3, were used for these releases. Although most trees died during the 5-year release period, it was not known if the hypoviruses persisted in the C. parasitica population at the two sites. When the experimental plots were revisited in 1994, few chestnut trees were found. The exception was one plot containing coppice sprouts that had grown from the root collars of the original trees. The authors intensively sampled C. parasitica from experimental plots and screened recovered isolates for double-stranded RNA (dsRNA). None of the isolates contained CHV-1; only six isolates contained CHV-3, all from the plots with the coppice sprouts. CHV-4, which occurs naturally in West Virginia forests and in two released isolates, hybridized to dsRNA from the isolates containing CHV-3, indicating mixed infections. CHV-4 also hybridized to dsRNA from other isolates sampled inside and outside the treated plots. In contrast to CHV-1 and CHV-3, however, CHV-4 has little effect on the growth or phenotype of C. parasitica. The limited persistence of CHV-1 and CHV-3 may have resulted when the C. parasitica population was reduced in size due to the failure of chestnut trees to resprout because of competition from other hardwood species. Résumé Bien que les hypovirus de Cryphonectria aient remporté un réel succès comme agents de lutte biologique contre le chancre du châtaignier en Europe, leur succès en Amérique du nord a été limité. Des applications d'hypovirus ont été faites en 1978,1982 en Virginie de l'ouest dans deux sites forestiers à fortes densités de régénérations de châtaigniers. Le CHV-1 originaire d'Europe ainsi que des isolats américains contenant le CHV-3 ont été utilisés dans ces essais. Bien que la plupart des arbres soient morts pendant les cinq ans de l'application, on ne sait pas si les hypovirus ont persisté dans la population de Cryphonectria parasitica. Quand les parcelles expérimentales ont été revisitées en 1994, peu de châtaigniers ont été trouvés. Un site faisait exception qui était un taillis de rejets issu de racines de souches. Nous avons échantillonné intensivement le C. parasitica dans les placettes et le dsRNA a été examiné dans les isolats obtenus. Parmi tous les isolats provenant des placettes de taillis, aucun ne contenait CHV-1 et seulement six contenaient CHV-3. CHV-4 qui existe naturellement dans les forêts en Virginie de l'ouest et dans deux des isolats appliqués, s'hybridait avec le dsRNA d'autres isolats contenant CHV-3, ce qui indique des infections mixtes. CHV-4 s'hybridait aussi avec le dsRNA d'autres isolats recueillis dans ou au dehors des placettes traitées. Contrairement à CHV1 et à CHV-3, CHV-4 a cependant peu d'effet sur la croissance et le phénotype de C. parasitica. La persistance limitée de CHV-1 et de CHV-3 peut avoir résulté de la réduction de la population de C. parasitica par un manque de rejets de châtaigniers dûà la compétition avec les autres espèces de feuillus. Zusammenfassung Währenddem der Einsatz von Cryphonectria Hypoviren zur biologischen Bekämpfung des Kastanienrindenkrebses in Europa relativ erfolgreich war, stimmt dies in Nordamerika nur begrenzt. In West-Virginia wurden in den Jahren 1978,82 Hypoviren in Experimenten an zwei Waldstandorten mit hoher Dichte regenerierender Edelkastanien freigesetzt. Cryphonectria hypovirus 1 (CHV-1) von Europa und amerikanische Isolate von Cryphonectria parasitica, die CHV-3 enthielten, wurden für diese Freisetzungsversuche verwendet. Obschon die meisten Bäume während der fünfjährigen Freisetzungsperiode abstarben, war unklar, ob die Hypoviren in der C. parasitica Population überlebten. Als die Versuchsflächen im Jahre 1994 erneut aufgesucht wurden, konnten nur noch wenige Edelkastanien gefunden werden mit Ausnahme einer Fläche, auf der die Wurzelanläufe ursprünglicher Bäume Stockausschläge trugen. Zahlreiche C. parasitica Stämme wurden von den Versuchsflächen gewonnen und auf Besiedlung mit dsRNA untersucht. Keines der Isolate enthielt CHV-1; nur sechs Isolate, welche alle von der Fläche mit den Stockausschlägen stammten, enthielten CHV-3. CHV-4, das natürlich in den Wäldern West-Viriginias vorkommt und in zwei der freigesetzten Isolate vorhanden war, hybridisierte mit dsRNA aus den Isolaten, die CHV-3 enthielten, was auf eine Mischinfektion hindeutet. CHV-4 hybridisierte auch mit dsRNA aus anderen Isolaten, die innerhalb und ausserhalb der behandelten Versuchsflächen gesammelt wurden. Im Gegensatz zu CHV-1 und CHV-3 war der Einfluss von CHV-4 auf den Phänotyp von C. parasitica gering. Die begrenzte Persistenz von CHV-1 und CHV-3 wird möglicherweise durch die Abnahme der C. parasitica Population als Folge des Ausbleibens der Regeneration der Edelkastanie bedingt. Erschwerend für die Edelkastanien dürfte sich zudem die Konkurrenz mit anderen Laubhölzern auswirken. [source] Persistence of a biocontrol strain of Phlebiopsis gigantea in conifer stumps and its effects on within-species genetic diversityFOREST PATHOLOGY, Issue 5 2001E. J. Vainio Fungal isolations and genetic fingerprinting were used to determine whether Phlebiopsis gigantea stump treatment against Heterobasidion annosum sl. using a single genotype (Rotstop) would affect the genetic diversity of P. gigantea populations. The survival time of P. gigantea was longer in Norway spruce (Picea abies) stumps compared to Scots pine (Pinus sylvestris) as no isolates were obtained from pine stumps 6 years after treatment, whereas in about half of the spruce stumps the fungus was still present. The usage of Rotstop did not seem to increase the occurrence of the fungus 5 years after the treatment in fresh (1-year-old) untreated stumps within the same forest stands. All the isolates from the 6-year-old treated spruce stumps were identical in genotype with the Rotstop-strain, whereas all isolates from the fresh untreated spruce and pine stumps differed from it. Within the treated pine stand, the biocontrol usage seemed to have caused a slight reduction in genetic markers not related to Rotstop, but there were no statistically significant differences between the marker frequencies and the local natural population. Thus, Rotstop is not likely to cause any immediate threat to the genetic diversity of P. gigantea. Persistance dans les souches de conifères d'un génotype de Phlebiopsis gigantea utilisée en lutte biologique, et effets sur la diversité génétique de l'espèce L'isolement et l'empreinte génétique ont été utilisés pour savoir si le traitement de souches contre Heterobasidion annosum avec un seul génotype de Phlebiopsis gigantea (Rotstop) peut affecter la diversité génétique des populations de P. gigantea. La durée de survie de P. gigantea a été plus longue dans les souches de Picea abies que dans celles de Pinus sylvestris. Chez celles-ci, aucun isolat n'a été obtenu six ans après le traitement alors que chez environ la moitié des souches d'épicéa le champignon était encore présent. Dans les mêmes peuplements, cinq ans après l'application du Rotstop, l'incidence du champignon ne semblait pas avoir augmenté chez les souches fraîches non traitées, âgées de un an. Tous les isolats obtenus à partir des souches traitées six ans auparavant avaient le même génotype que l'isolat du Rotstop, alors que tous ceux issus de souches fraîches non traitées d'épicéa et de pin étaient différents. Chez le peuplement de pins, le traitement biologique semblait avoir causé une légère réduction des marqueurs génétiques non liés au Rotstop, mais leur fréquence n'était pas statistiquement différente de celle de la population naturelle locale. Ainsi, il apparaît peu probable que le Rotstop soit une menace immédiate pour la diversité génétique du P. gigantea. Persistenz eines Phlebiopsis gigantea -Isolates in Koniferenstümpfen und seine Auswirkungen auf die intraspezifische genetische Diversität Mit Isolierungen und genetischem Fingerprinting wurde untersucht, ob eine Stumpfbehandlung mit einem einzelnen Genotyp von Phlebiopsis gigantea (Rotstop) gegen Heterobasidion annosum sl. die genetische Diversität von P. gigantea -Populationen beeinträchtigen könnte. P. giganteaüberlebte auf Stümpfen von Picea abies länger als auf solchen von Pinus sylvestris. Auf Kiefernstümpfen konnte der Pilz sechs Jahre nach der Behandlung nicht mehr nachgewiesen werden, während er auf 50% der Fichtenstümpfe noch vorhanden war. Eine Rotstop-Anwendung 5 Jahre zuvor hatte offenbar keinen Einfluss auf das Vorkommen von P. gigantea in frischen (einjährigen) unbehandelten Stümpfen im gleichen Bestand. Alle Isolate von den sechs Jahre alten behandelten Fichtenstümpfen hatten den gleichen Genotyp wie das Rotstop-Isolat, während alle Isolate von den frischen (unbehandelten) Fichten-und Kiefernstümpfen anderen Genotypen angehörten. In dem behandelten Kiefernbestand war die Frequenz der nicht mit dem Rotstop-Isolat assoziierten genetischen Marker etwas verringert, der Unterschied zur lokalen natürlichen Population war aber statistisch nicht signifikant. Die Anwendung von Rotstop dürfte somit keine kurzfristige Bedrohung der genetischen Diversität von P. gigantea darstellen. [source] Persistence and the four-factor model in the Australian funds market: a noteACCOUNTING & FINANCE, Issue 1 2010Jacquelyn E. Humphrey G11; G23 Abstract We investigate whether Australian fund managers are able to deliver persistent performance using Carhart's (1997) four-factor model. Short- and long-term persistence is examined and the sample is also divided into unit trusts and superannuation funds. We do not find evidence of persistence in any sample of funds. We find that winner (loser) funds tend to hold past winner (loser) stocks. Winner and loser unit trusts both appear to have positive exposure to small stocks. [source] The Substance of Sexual Difference: Change and Persistence in Representations of the Body in Eighteenth,Century EnglandGENDER & HISTORY, Issue 2 2002Karen HarveyArticle first published online: 16 DEC 200 The claims of Thomas Laqueur for a shift from a one,sex to a two,sex model of sexual difference are incorporated into many recent histories of gender in England between 1650 and 1850. Yet the Laqueurian narrative is not supported by discussions of the substance of sexual difference in eighteenth,century erotic books. This article argues that different models of sexual difference were not mutually exclusive and did not change in linear fashion, but that the themes of sameness and difference were strategically deployed in the same period. Thus, there was an enduring synchronic diversity which undermines claims for linear transformation. [source] Potential role of radial glia in adult neurogenesis of teleost fishGLIA, Issue 1 2003Günther K.H. Zupanc Abstract Persistence of radial glia within the adult central nervous system is a widespread phenomenon among fish. Based on a series of studies in the teleost species Apteronotus leptorhynchus, we propose that one function of this persistence is the involvement of radial glia in adult neurogenesis, i.e., the generation and further development of new neurons in the adult central nervous system. In particular, evidence has been obtained for the involvement of radial glia in the guidance of migrating young neurons in both the intact and the regenerating brain; for a possible role as precursor cells from which new neurons arise; and for its role as a source of trophic substances promoting the generation, differentiation, and/or survival of new neurons. These functions contribute not only to the potential of the intact brain to generate new neurons continuously, and of the injured brain to replace damaged cells by newly generated ones, but they also provide an essential part of the cellular substrate of behavioral plasticity. GLIA 43:77,86, 2003. © 2003 Wiley-Liss, Inc. [source] The Occurrence and Persistence of MTBE in Groundwater in Windham, Maine, USAGROUND WATER MONITORING & REMEDIATION, Issue 2 2010John M. Peckenham A study was conducted from July 1998 through November 2007 on the occurrence and distribution of the fuel oxygenate methyl tert-butyl ether (MTBE) in a large sand and gravel aquifer located in southern Maine. MTBE was detected in 44% of 129 water samples collected from monitoring wells in concentrations up to 38.7 µg/L (reporting limit = 0.1 µg/L). The number of wells with detectable quantities of MTBE declined slightly between 1999 and 2007, but in general MTBE persisted throughout the period of study. Overall, MTBE was detected more frequently in the shallow and more transmissive parts of the aquifer. There was a statistically significant difference (p < 0.001) for MTBE concentrations relative to nearby land uses. MTBE was detected in 83% of the samples collected from wells in low-density residential areas, in 50% of samples from urban areas, and in 60% of samples from undeveloped areas. The concentrations of MTBE in the test wells were compared across the sample dates for trends and seven wells had a positive trend (Mann,Kendall statistic), but none was significant at p < 0.05. Nine wells had a negative trend, but only one was significant at p < 0.05. Three wells had no trend. The absence of strong or even consistent trends indicates that MTBE persists in shallow groundwater, even after gasoline formulations were changed to reduce or eliminate MTBE. [source] Venous needle dislodgement during hemodialysis: An unresolved risk of catastrophic hemorrhageHEMODIALYSIS INTERNATIONAL, Issue 1 2005S. Sandroni Venous line disconnection or needle dislodgement during hemodialysis with resultant hemorrhage is a potentially lethal event. The risk is compounded by the frequent failure of standard dialysis machines to detect the event, as blood flow through the venous needle typically creates enough back pressure to prevent venous pressure alarms even if the needle is completely out of the patient's AV access. Manufacturers are well aware of the risk and device literature contains specific warnings about it. The FDA publishes reports on its website about these events; so far this year there have been seven reported events with five deaths. Informal sources indicate that the actual (unreported) occurrence is much more frequent; we are aware of four additional events within our region alone. Efforts to reduce the risk include protocols requiring the access needles to always be visible, and use of enuresis detection devices. Anecdotal experience with these efforts suggests they are not highly effective. Protocols requiring documentation of more frequent needle site checks or alternate methods of securing the needles have not been formally evaluated. However, such efforts do not address the primary problem: there is a need for an engineered solution to this problem. Requirements for such a solution include: reliable detection of needle position and blood flow discrepancies, a useful alarm, and feedback to stop the blood pump. Persistence of this problem raises issues of regulatory oversight. [source] Persistence, Principle and Patriotism in the Making of the Union of 1707: The Revolution, Scottish Parliament and the squadrone volanteHISTORY, Issue 306 2007DEREK J. PATRICK Since the 1960s most historians of the Union of 1707 have considered it a less than glorious chapter in Scotland's history. Driven by ambition and greed, Scots politicians, covetous of English wealth and swayed by promises and bribes, bartered their nation's independence for personal gain. Those genuinely committed to political union were in a minority. The following article maintains that this interpretation is based on an essentially short-term approach to the subject. Concentrating on the worsening relations between Scotland and England in the years immediately preceding the Union gives a distorted impression of what was a more enduring concern. It suggests the Revolution of 1688,9 had a far greater impact on the politics of union than previously anticipated, with the religious and political freedoms it guaranteed shaping the beliefs of a large number of Scots MPs who sat in Parliament 1706,7, almost half of whom had been members of King William's Convention Parliament with a majority supporting union. Focusing on the squadrone volante, one of the two much-maligned Scots unionist parties , the article traces the ideological roots of its key members and illustrates the various factors that led them to endorse an incorporating union which offered security for presbyterianism and a solution to Scotland's economic underdevelopment. Not denying that management and ambition played a significant part in securing the Union, it highlights the fact that amongst the Scottish political elite there was also a degree of genuine commitment and principled support. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||