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Potential Effects (potential + effects)
Selected AbstractsPotential Effects of Passenger Pigeon Flocks on the Structure and Composition of Presettlement Forests of Eastern North AmericaCONSERVATION BIOLOGY, Issue 6 2003JOSHUA W. ELLSWORTH We suggest that the activities of roosting and nesting Passenger Pigeons caused widespread, frequent disturbances in presettlement eastern forests through tree limb and stem breakage and nutrient deposition from pigeon excrement. We suspect that the deposition of fine fuels resulting from such disturbances may have influenced fire intensity and frequency in presettlement forests. Further, we propose that consumption of vast quantities of acorns by pigeons during the spring breeding season may partially explain the dominance of white oak (Quercus alba) throughout much of the presettlement north-central hardwoods region. Consequently, the pigeon's extinction may have facilitated the increase and expansion of northern red oak (Quercus rubra) during the twentieth century. Although it is difficult to accurately quantify how physical and chemical disturbances and mast consumption by Passenger Pigeon flocks affected forest ecology, we suspect they shaped landscape structure and species composition in eastern forests prior to the twentieth century. We believe their impact should be accounted for in estimates of the range of natural variability of conditions in eastern hardwood forests. Resumen:,Consideramos los posibles efectos que pudieron haber tenido parvadas de Palomas Migratorias (Ectopistes migratorius) sobre el régimen de perturbación y la composición de especies de bosques en Norte América oriental antes de la colonización. Sugerimos que las actividades de perchado y anidación de las palomas causaron perturbaciones frecuentes y extensas en los bosques orientales antes de la colonización por medio de la ruptura de ramas y tallos de árboles y la deposición de nutrientes del excremento de las palomas. Sospechamos que la deposición de combustibles resultantes de tales perturbaciones pudo haber influido en la intensidad y frecuencia de incendios forestales. Más aún, proponemos que el consumo de grandes cantidades de bellotas por las palomas en la primavera puede parcialmente explicar la dominancia de roble blanco (Quercus alba) en muchos de los bosques nor-orientales. En consecuencia, la extinción de la paloma pudo haber facilitado el incremento y expansión del roble rojo (Quercus rubra) durante el siglo veinte. Aunque es difícil cuantificar con precisión como las perturbaciones físicas y químicas y el consumo masivo por parvadas de palomas migratorias afectaron a la ecología forestal, sospechamos que modelaron la estructura del paisaje y la composición de especies en los bosques orientales antes del siglo veinte. Creemos que su impacto debería ser considerado cuando se hacen estimaciones del rango de variabilidad natural de las condiciones en bosques orientales de maderas duras. [source] The Ozone Component of Global Change: Potential Effects on Agricultural and Horticultural Plant Yield, Product Quality and Interactions with Invasive SpeciesJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 4 2009Fitzgerald Booker The productivity, product quality and competitive ability of important agricultural and horticultural plants in many regions of the world may be adversely affected by current and anticipated concentrations of ground-level ozone (O3). Exposure to elevated O3 typically results in suppressed photosynthesis, accelerated senescence, decreased growth and lower yields. Various approaches used to evaluate O3 effects generally concur that current yield losses range from 5% to 15% among sensitive plants. There is, however, considerable genetic variability in plant responses to O3. To illustrate this, we show that ambient O3 concentrations in the eastern United States cause substantially different levels of damage to otherwise similar snap bean cultivars. Largely undesirable effects of O3 can also occur in seed and fruit chemistry as well as in forage nutritive value, with consequences for animal production. Ozone may alter herbicide efficacy and foster establishment of some invasive species. We conclude that current and projected levels of O3 in many regions worldwide are toxic to sensitive plants of agricultural and horticultural significance. Plant breeding that incorporates O3 sensitivity into selection strategies will be increasingly necessary to achieve sustainable production with changing atmospheric composition, while reductions in O3 precursor emissions will likely benefit world food production and reduce atmospheric concentrations of an important greenhouse gas. [source] Invasion Possibility and Potential Effects of Rhus typhina on Beijing MunicipalityJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 5 2008Guangmei Wang Abstract Rhus typhina, an alien species introduced from North America, was identified as a main afforestation species in Beijing municipality. However, its invasiveness is still at odds. To clarify this problem, we applied the North American Screening System and the Australian Screening System to preliminarily predict its invasion possibility. Both screening systems gave the same recommendation to "reject". The geographical distribution was surveyed, with the population features of R. typhina against the native plant communities being assessed. With anthropogenic assistance, R. typhina has been scattered on almost all habitats from downtown to mountains, including roadsides, farmlands and protected areas. As a clonal shrub, R. typhina possessed a high spreading rate, varying from 6.3 m/3 years at sterile habitats to 6.7 m/3 years at fertile ones. Significantly lower species richness, individual density and diversity were observed in the R. typhina community than those of the native Vitex negundo Linn.var. heterophylla (Franch.) Rehd. community at both sterile and fertile habitats. Continual wide plantation of R. typhina may further foster its population expansion, which helps the species to overcome spatial isolation. The fact that each root fragment can develop into a new individual makes R. typhina very difficult to be eradicated once established. From a biological point of view, we believe that R. typhina is a plant invader in Beijing. We therefore suggest the government should remove the name of R. typhina from the main tree species list in afforesting Beijing. [source] Osmotic Potential Effects on In Vitro Growth, Morphology and Pathogenicity of Macrophomina phaseolinaJOURNAL OF PHYTOPATHOLOGY, Issue 7-8 2003D. Cervantes-García Abstract The influence of osmotic potential (,s) on in vitro growth and morphology of four isolates of Macrophomina phaseolina was studied using potato-glucose-agar adjusted to different osmotic potentials with KCl, NaCl and sucrose. The effect of NaCl on M. phaseolina pathogenicity in common bean was determined and then related to the pathogenicity of each isolate on seeds of 12 differential common bean cultivars. The three sources of ,s reduced M. phaseolina growth under in vitro conditions, whereby NaCl caused the highest negative effects. The high solute concentrations reduced the synthesis of mycelial pigments and the size and shape of microsclerotia. Pathogenicity of M. phaseolina in common bean seeds was reduced by high concentrations of NaCl but no relationship was found between the tolerance to high ,s concentrations under in vitro conditions and M. phaseolina pathogenicity in common bean seeds. [source] Pulsed Laser Polymerization of Alkyl Acrylates: Potential Effects of the Oxygen Presence and High Laser Power,MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 1 2006Patrice Castignolles Abstract Summary: Unexpected difficulties are encountered in the determination of propagation rate coefficients (kp) in free radical polymerization of alkyl acrylates by pulsed laser polymerization (PLP), mainly due to intramolecular transfer to polymer.1 This article is focused on the role played by the high laser power in these difficulties and the possible reactions of mid-chain radical with residual oxygen. Removing the oxygen by simple bubbling of nitrogen is sufficient to avoid alteration of the polymerization kinetics of acrylates by residual oxygen under PLP conditions. Moreover, no degradation of polymer (or solvent) has been detected after irradiation with the high laser power typically used in PLP experiments. However, it has been shown that this high laser power completely prevents from having a temporally and spatially homogeneous radical concentration in the PLP cell. A model is proposed here to simulate the pulsed laser polymerization taking initiator consumption and laser energy absorption into account. According to our simulation results, this non-negligible initiator consumption and laser power absorption can indeed have a positive influence, i.e., it favors the obtainment of a bimodal molar mass distribution fulfilling the IUPAC consistency criteria. This observation may contradict the idea that PLP-SEC is not suitable to determine accurate kp values for acrylates above 20,30,°C. Instantaneous MMDs formed after N pulses. Simulation taking initiator consumption and laser absorption into account. [source] Response: DonorNet and the Potential Effects on Organ UtilizationAMERICAN JOURNAL OF TRANSPLANTATION, Issue 10 2010L. K. Kayler No abstract is available for this article. [source] Response: DonorNet and the Potential Effects on Organ UtilizationAMERICAN JOURNAL OF TRANSPLANTATION, Issue 10 2010D. A. Gerber No abstract is available for this article. [source] DonorNet and the Potential Effects on Organ UtilizationAMERICAN JOURNAL OF TRANSPLANTATION, Issue 4p2 2010D. A. Gerber The evolution of communication as donor data flows from organ procurement organization to transplant centers has evolved with the incorporation of DonorNet 2007® into the UNetSM system. The ensuing study looks at DonorNet's impact on this process. We established defined time periods for comparison purposes. The study looked at match number for organ placement and overall organ utilization with a focus on ischemia time and graft outcomes. The results of the study demonstrate no significant change in the median match number of organ placement in liver or kidney transplantation. Changes in discard rates were varied amongst transplanted organs and there were noticeable changes in organ sharing with an increase in local allocation for kidney and liver and an ensuing decrease in regional and national distribution. There were no significant differences in the outcomes of livers and kidneys with low offer numbers compared with those with high offer numbers. Overall the study suggests a modest impact by DonorNet on organ placement and utilization, but a longer term study would need to be done to fully evaluate its impact. [source] Evaluation of the methoxytriazine herbicide prometon using a short-term fathead minnow reproduction test and a suite of in vitro bioassaysENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2006Daniel L. Villeneuve Abstract Prometon is one of the most consistently detected herbicides in the U.S. environment. However, no previous assessment of the potential for prometon or related methoxytriazine herbicides to act as endocrine-disrupting chemicals has been conducted. This study used an array of in vitro bioassays to assess whether prometon, atraton, terbumeton, or secbumeton might act as potent (ant)agonists of the aryl hydrocarbon, estrogen, androgen, or glucocorticoid receptors or as aromatase inhibitors or inducers in vitro. Potential effects of prometon were also evaluated using a 21-d fathead minnow reproduction assay. Concentrations of methoxytriazines, as great as 1 mg/L (4.4 ,M), did not induce significant dioxin-like responses in H4IIE-luc cells, estrogenic responses in MVLN cells, or androgen or glucocorticoid receptor,mediated responses in MDA-kb2 cells, nor did the methoxytriazines significantly affect aromatase activity in vitro. In the fathead minnow assay, exposure to 20, 200, or 1,000 ,g prometon/L significantly reduced the weight of the male fat pad (an androgen-responsive tissue) relative to body weight. Exposure to 20 ,g prometon/L significantly increased female plasma testosterone concentrations, but the effect was not observed at greater concentrations. Overall, prometon did not significantly reduce fecundity over the 21-d exposure, nor were other endpoints, including plasma vitellogenin and estradiol concentrations, brain and ovary aromatase activity, and male tubercle index, significantly affected. Evidence from our work suggests that prometon may cause subtle endocrine and/or reproductive effects in fathead minnows, but no clear mechanism of action was observed. The relevance of these effects to hazard assessment for the pesticide is uncertain. [source] Biochemical and histopathological effects in pearl dace (Margariscus margarita) chronically exposed to a synthetic estrogen in a whole lake experimentENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2006Vince P. Palace Abstract Potential effects of exposure to the synthetic estrogen 17,-ethynylestradiol (EE2) were examined in several species of fish from a lake experimentally treated with environmentally relevant concentrations of the contaminant. Ethynylestradiol was added to Lake 260, a small Precambrian shield lake at the Experimental Lakes Area in northwestern Ontario, Canada, from May to October of 2001, 2002, and 2003. Mean concentrations of EE2 in epilimnetic waters ranged between 4.5 and 8.1 ng/L during the three years, with overall means of 6.1 (±2.8), 5.0 (±1.8), and 4.8 (±1.0) ng/L for the three years, respectively. Male and female pearl dace (Margariscus margarita) captured after EE2 additions began contained up to 4,000-fold higher concentrations of the egg yolk precursor vitellogenin than fish captured from the same lake before the EE2 additions or when compared to fish from reference lakes. Edema in the ovaries, inhibited development of testicular tissue, intersex, and histopathological kidney lesions were all evident in fish exposed to EE2. Some indications that EE2 exposure affected in vitro steroidogenic capacity of the ovaries and the testes existed, although results were not always consistent between years. Pearl dace abundance was similar in the lake treated with EE2 and the reference lake. A trend exists toward a reduced overall population of pearl dace from the treated and reference lakes, as do indications that young-of-the-year size classes are less abundant in the EE2-treated lake. Biochemical and histopathological impacts observed in fish exposed to EE2 in this study have not yet been linked to clear population level impacts in pearl dace. Monitoring of these populations is ongoing. [source] Potential effects of herbicides on native amphibians: A hierarchical approach to ecotoxicology research and risk assessmentENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2004Dean G. Thompson No abstract is available for this article. [source] Voltinism flexibility of a riverine dragonfly along thermal gradientsGLOBAL CHANGE BIOLOGY, Issue 3 2008ERIK BRAUNE Abstract Potential effects of future warming should be reflected in life history patterns of aquatic organisms observed in warmer climates or in habitats that are different in ambient temperature. In the special case of the dragonfly Gomphus vulgatissimus (L.) (Odonata: Gomphidae) previous research suggests that voltinism decreases from south to north. We analysed data on voltinism from 11 sample sites along a latitudinal gradient from about 44°N to 53°N, comprising small streams to medium-sized rivers. Furthermore, to simulate different conditions and to allow projections for future climate change scenarios, we developed a population dynamic model based on a projection matrix approach. The parameters of the model are dependent on temperature and day length. Our field results indicate a decrease in voltinism along the latitudinal gradient from southern to northern Europe and a corresponding increase of voltinism with higher temperatures. An increase in voltinism with width of the running water implies an effect of varying habitat temperature. Under the impact of global warming, our model predicts an increased development speed, particularly in the northern part of the latitudinal gradient, an extension of the northern range limit and changes in phenology of G. vulgatissimus, leading to an extension of the flight season in certain regions along the gradient. [source] Potential effects of warming and drying on peatland plant community compositionGLOBAL CHANGE BIOLOGY, Issue 2 2003Jake F. Weltzin Abstract Boreal peatlands may be particularly vulnerable to climate change, because temperature regimes that currently constrain biological activity in these regions are predicted to increase substantially within the next century. Changes in peatland plant community composition in response to climate change may alter nutrient availability, energy budgets, trace gas fluxes, and carbon storage. We investigated plant community response to warming and drying in a field mesocosm experiment in northern Minnesota, USA. Large intact soil monoliths removed from a bog and a fen received three infrared warming treatments crossed with three water-table treatments (n = 3) for five years. Foliar cover of each species was estimated annually. In the bog, increases in soil temperature and decreases in water-table elevation increased cover of shrubs by 50% and decreased cover of graminoids by 50%. The response of shrubs to warming was distinctly species-specific, and ranged from increases (for Andromeda glaucophylla) to decreases (for Kalmia polifolia). In the fens, changes in plant cover were driven primarily by changes in water-table elevation, and responses were species- and lifeform-specific: increases in water-table elevation increased cover of graminoids , in particular Carex lasiocarpa and Carex livida, as well as mosses. In contrast, decreases in water-table elevation increased cover of shrubs, in particular A. glaucophylla and Chamaedaphne calyculata. The differential and sometimes opposite response of species and lifeforms to the treatments suggest that the structure and function of both bog and fen plant communities will change , in different directions or at different magnitudes , in response to warming and/or changes in water-table elevation that may accompany regional or global climate change. [source] The Agreement on Textiles and Clothing: Potential effects on gendered employment in PakistanINTERNATIONAL LABOUR REVIEW, Issue 4 2005Karin Astrid SIEGMANN First page of article [source] Potential effects of a major hurricane on Atlantic bottlenose dolphin (Tursiops truncatus) reproduction in the Mississippi SoundMARINE MAMMAL SCIENCE, Issue 3 2010Lance J. Miller First page of article [source] Potential effects of tyramine on the transition to reproductive workers in honeybees (Apis mellifera L.)PHYSIOLOGICAL ENTOMOLOGY, Issue 2 2007KEN SASAKI Abstract To explore the role of brain tyramine in reproductive worker honeybees, its effects after injection and oral treatment on brain dopamine levels and ovarian development in queenless worker honeybees are determined. Both tyramine injection and oral treatment in 10-day-old queenless bees leads to tyramine transportation into the brain and significantly elevates brain dopamine levels as a function of the tyramine concentration. Ovarian diameters are significantly larger in 10-day-old queenless bees treated with tyramine compared with queenless bees of the same age without tyramine treatment. Results on yolk formation in the ovary support the finding of increased ovarian diameter, suggesting that oral tyramine treatment accelerates ovarian development through dopamine effects and/or direct effects of tyramine on the ovary in queenless bees. Thus, tyramine has potential effects on the enhancement of brain dopamine levels and the acceleration of ovarian development for the transition of normal workers to reproductive worker honeybees. [source] Workplace air quality and lung function among dental laboratory technicians,AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 2 2006Suh-Woan Hu DDS Abstract Background Dental laboratory technicians are exposed to dust and/or methyl methacrylate (MMA) in the workplace. Potential effects of the exposures on lung function merit further clarification. Methods This study measured lung function of 45 dental technicians, before and after shifts, on 3 workdays and monitored workplace concentrations of particulate matter with aerodynamic diameter less than 2.5 mm (PM2.5) and MMA in five dental laboratories in Taiwan. Base metals in particles were analyzed by X-ray fluorescence. Repeated measurement analysis was applied to estimate potential effects of PM2.5 on pulmonary function. Results PM2.5 ranged from 26 µg/m3 to 664 µg/m3 and levels of MMA were low in these laboratories. Nickel, cobalt, and chromium were detected in the particles. After controlling for important factors, PM2.5 was associated with a small decrease in forced vital capacity and forced expiratory flow in one second. Conclusion Workplace PM2.5 was associated with a non-significant decrease in lung function of dental technicians. Am. J. Ind. Med., 2006. © 2005 Wiley-Liss, Inc. [source] Forks in the Road: Choices in Procedures for Designing Wildland LinkagesCONSERVATION BIOLOGY, Issue 4 2008PAUL BEIER análisis de sensibilidad; conectividad; corredor de vida silvestre; enlace; diseño de reservas Abstract:,Models are commonly used to identify lands that will best maintain the ability of wildlife to move between wildland blocks through matrix lands after the remaining matrix has become incompatible with wildlife movement. We offer a roadmap of 16 choices and assumptions that arise in designing linkages to facilitate movement or gene flow of focal species between 2 or more predefined wildland blocks. We recommend designing linkages to serve multiple (rather than one) focal species likely to serve as a collective umbrella for all native species and ecological processes, explicitly acknowledging untested assumptions, and using uncertainty analysis to illustrate potential effects of model uncertainty. Such uncertainty is best displayed to stakeholders as maps of modeled linkages under different assumptions. We also recommend modeling corridor dwellers (species that require more than one generation to move their genes between wildland blocks) differently from passage species (for which an individual can move between wildland blocks within a few weeks). We identify a problem, which we call the subjective translation problem, that arises because the analyst must subjectively decide how to translate measurements of resource selection into resistance. This problem can be overcome by estimating resistance from observations of animal movement, genetic distances, or interpatch movements. There is room for substantial improvement in the procedures used to design linkages robust to climate change and in tools that allow stakeholders to compare an optimal linkage design to alternative designs that minimize costs or achieve other conservation goals. Resumen:,Los modelos son utilizados comúnmente para identificar tierras que mantengan la habilidad de la vida silvestre para moverse entre bloques de tierras silvestres a través de una matriz de tierras que habían sido incompatibles con el movimiento de vida silvestre. Ofrecemos 16 opciones y supuestos que se originan en el diseño de enlaces para facilitar el movimiento o el flujo de genes de especies focales entre 2 o más bloques de tierras silvestres predefinidos. Recomendamos el diseño de enlaces que sirvan a múltiples (y solo a una) especies focales que funjan como una sombrilla colectiva para todas las especies nativas y los procesos ecológicos, que explícitamente admitan supuestos no comprobados y que utilicen análisis de incertidumbre para ilustrar efectos potenciales de la incertidumbre del modelo. La mejor forma de mostrar tal incertidumbre a los interesados es mediante mapas de los enlaces modelados bajo diferentes suposiciones. También recomendamos modelar a habitantes de corredores (especies que requieren más de una generación para mover sus genes entre bloques de tierra silvestre) de manera diferente que las especies pasajeras (un individuo se puede mover entre bloques de tierras silvestres en unas cuantas semanas). Identificamos un problema, que denominamos el problema de traducción subjetiva, que surge porque un analista debe decidir subjetivamente cómo traducir medidas de selección de recursos a resistencia. Este problema puede ser sobrepuesto mediante la estimación de la resistencia a partir de observaciones de movimientos de animales, distancias genéticas o movimientos entre fragmentos. Hay espacio para la mejora sustancial de los procedimientos utilizados para diseñar enlaces robustos ante el cambio climático y en herramientas que permiten que los interesados comparen un diseño óptimo con diseños alternativos que minimicen costos o alcancen otras metas de conservación. [source] Using Population Count Data to Assess the Effects of Changing River Flow on an Endangered Riparian PlantCONSERVATION BIOLOGY, Issue 4 2006DIANE M. THOMSON análisis de viabilidad poblacional; gestión ribereña; método de difusión; presas; riesgo de extinción Abstract:,Methods for using simple population count data to project extinction risk have been the focus of much recent theoretical work, but few researchers have used these approaches to address management questions. We analyzed 15 years of census data on the federally endangered endemic riparian plant Pityopsis ruthii (Small) with the diffusion approximation (DA). Our goals were to evaluate relative extinction risk among populations in two different watersheds (in Tennessee, U.S.A.) and potential effects of variation in managed river flow on population dynamics. Populations in both watersheds had high projected risks of extinction within 50 years, but the causes of this risk differed. Populations of P. ruthii on the Hiwassee River had higher initial population sizes but significantly lower average growth rates than those on the Ocoee River. The only populations with low predicted short-term extinction risk were on the Ocoee. Growth rates for populations on both rivers were significantly reduced during periods of lower river flow. We found only marginal evidence of a quadratic relationship between population performance and flow. These patterns are consistent with the idea that low flows affect P. ruthii due to growth of competing vegetation, but the degree to which very high flows may reduce population growth is still unclear. Simulations indicated that populations were most sensitive to growth rates in low-flow years, but small changes in the frequency of these periods did not strongly increase risk for most populations. Consistent with results of other studies, DA estimates of extinction risk had wide confidence limits. Still, our results yielded several valuable insights, including the need for greater monitoring of populations on the Hiwassee and the importance of low-flow years to population growth. Our work illustrates the potential value of simple methods for analyzing count data despite the challenges posed by uncertainty in estimates of extinction risk. Resumen:,Los métodos que utilizan datos de conteos simples de la población para proyectar el riesgo de extinción han sido el foco reciente de mucho trabajo teórico, pero pocos investigadores han utilizado estos métodos para responder preguntas de gestión. Analizamos 15 años de datos de censos de la planta ribereña, endémica y federalmente en peligro Pityopsis ruthii (Small) mediante el método de difusión. Nuestras metas fueron evaluar el riesgo de extinción de poblaciones en dos cuencas hidrológicas distintas y con dos efectos potenciales de la variación del flujo de agua sobre la dinámica de la población. Las poblaciones en ambas cuencas tenían alto riesgo de extinción proyectado a 50 años, pero las causas de este riesgo difirieron. Las poblaciones de P. ruthii en el Río Hiwassee tuvieron poblaciones iniciales más grandes, pero tasas de crecimiento significativamente menores, que las poblaciones en el Río Ocoee. Las únicas poblaciones con bajo riesgo de extinción pronosticado estaban en el Ocoee. Las tasas de crecimiento de las poblaciones en ambos ríos se redujeron significativamente durante períodos de bajo flujo en el río. Sólo encontramos evidencia marginal de la relación cuadrática entre el funcionamiento de la población y el flujo. Estos patrones son consistentes con la idea de que los bajos flujos afectan a P. ruthii debido al crecimiento de vegetación competitiva, pero aun no es claro el grado en que flujos muy grandes pueden reducir el crecimiento poblacional. Las simulaciones indicaron que las poblaciones son más sensibles a las tasas de crecimiento en años con bajo flujo en los ríos, pero pequeños cambios en la frecuencia de esos períodos no aumentaron el riesgo en la mayoría de las poblaciones. Consistentemente con los resultados de otros estudios, las estimaciones del riesgo de extinción mediante el método de difusión tienen amplios límites de confianza. Aun así, nuestros resultados aportaron varios conocimientos valiosos, incluyendo la necesidad de mayor monitoreo de las poblaciones en el Hiwassee y la importancia para el crecimiento poblacional de los años con bajo flujo. Nuestro trabajo ilustra el valor potencial de métodos sencillos de análisis de datos de conteo a pesar de los retos impuestos por la incertidumbre en las estimaciones del riesgo de extinción. [source] Implications of Climatic Warming for Conservation of Native Trees and Shrubs in FloridaCONSERVATION BIOLOGY, Issue 4 2001David W. Crumpacker Climatic-envelope models are useful for simultaneous investigation of many plant species whose range-limiting mechanisms are poorly known. They are most effectively applied in regions with strong temperature and moisture gradients and low relief. Their required databases are often relatively easy to obtain. We provide an example involving the effect of six annual warming scenarios, ranging from +1° C to +2° C and from +10% to ,20% annual precipitation (some have greater warming in winter than in summer), on 117 native woody species in Florida (U.S.A.). Tree species at their southern range boundaries in several parts of Florida are likely to be negatively affected by as little as 1° C warming if it is greater in winter than in summer or is accompanied by a 20% decrease in annual precipitation. Potential species responses to an identical type of 1° C warming may be different for some conservation areas in the same region of Florida. Potentially extensive disruption of some major woody ecosystems is predicted under certain types of 1° C annual warming and under all types of 2° C annual warming that were investigated. Additional consideration of nonclimatic factors suggests that many potential effects on species and ecosystems are not underestimates of actual effects over a 100-year period of warming. We recommend monitoring for decreased fertility and viability of ecologically important, temperate woody species near their southern range limits in Florida. Early detection of such changes in fitness might then provide time for mitigations designed to alleviate more serious subsequent effects on biodiversity. Control of invasive, non-native plant species and prevention of their additional introduction, human-assisted translocation of native subtropical plant species into previously temperate parts of Florida, and restoration of more natural hydrological regimes are examples of potentially useful mitigations if climatic warming continues. Resumen: Los modelos de procesos ecológicos y los modelos empíricos han sido usados para relacionar predicciones de cambio climático con los efectos en especies de plantas y vegetación. Los modelos climáticos son útiles para la investigación simultánea de muchas especies de plantas cuyos mecanismos limitantes de rango son poco conocidos. Estos modelos son más eficientemente aplicados en regiones con gradientes de temperatura y humedad fuertes y con relieve bajo. Las bases de datos requeridas son a menudo relativamente fáciles de adquirir. Proveemos un ejemplo que involucra el efecto de seis escenarios anuales de calentamiento con un rango de +1° C a +2° C y de +10% a ,20% de precipitación anual (algunos con rangos de calentamiento mayores en el invierno que en el verano), en 117 especies leñosas nativas de Florida ( E.U.A.). Las especies de árboles en sus límites de rango al sur en diversas partes de Florida son más factibles de ser negativamente afectadas por tan poco como 1° C de calentamiento, si este es mayor en el invierno que en el verano o si es acompañado por una disminución de un 20% de precipitación anual. Las respuestas potenciales de las especies a un tipo idéntico de calentamiento de 1° C puede ser diferente para algunas áreas de conservación en la misma región de Florida. Se predicen perturbaciones potencialmente extensivas en algunos ecosistemas leñosos principales investigados bajo ciertos tipos de calentamiento anual de 1° C y bajo todos los tipos de calentamiento anual de 2° C. Las consideraciones adicionales de factores no climáticos sugieren que muchos efectos potenciales sobre las especies y ecosistemas no son subestimaciones de los efectos actuales sobre un período de calentamiento de 100 años. Se recomienda el monitoreo de la disminución de la fertilidad y viabilidad de especies leñosas templadas ecológicamente importantes cerca de los límites sureños de sus rangos en la Florida. La detección temprana de estos cambios en adaptabilidad pueden proveer tiempo para mitigaciones diseñadas para aliviar efectos posteriores más serios en la biodiversidad. Algunos ejemplos de mitigaciones potencialmente útiles en caso de que el calentamiento global continúe incluyen el control de especies de plantas invasoras no nativas y la prevención de su introducción adicional, la translocación asistida por humanos de plantas nativas subtropicales en partes previamente templadas de Florida y la restauración de regimenes hidrológicos más naturales. [source] L -Amino acid load to enhance PET differentiation between tumor and inflammation: an in vitro study on 18F-FET uptakeCONTRAST MEDIA & MOLECULAR IMAGING, Issue 5 2006S. Laïque Abstract Labeled amino acids (AA) are tumor tracers for use in nuclear medecine. O -(2-[18F]fluoroethyl)- L -tyrosine (FET) is transported by the L -system, known to function as an exchanger. In vitro utilization of FET, after a preload or prior to an afterload of non radioactive L -amino acids, was evaluated in order to measure the potential effects of AA content on the distinction between tumor and inflammatory lesions. Cellular uptake of FET was studied on rat osteosarcoma cells (ROS 17/2.8) and human leukocytes, initially loaded with nonradioactive L -tyrosine or L -methionine. FET efflux was evaluated from cells loaded with nonradioactive L -phenylalanine after tracer uptake. ROS 17/2.8 showed a higher sensitivity to preload and afterload effects on cellular FET content as compared with the leukocytes. We conclude that preload with L -tyrosine, prior to the administration of FET, may be a potential procedure to improve PET differentiation between tumor and inflammatory lesions. Copyright © 2006 John Wiley & Sons, Ltd. [source] THE APPRENDI-BLAKELY CASES: SENTENCING REFORM COUNTER REVOLUTION?CRIMINOLOGY AND PUBLIC POLICY, Issue 3 2007RICHARD S. FRASE Recent Supreme Court decisions have extended jury trial rights and beyond-reasonable-doubt proof standards to certain sentence-enhancement facts. The first two cases, Apprendi v. New Jersey and Ring v. Arizona, were narrow in scope and relatively uncontroversial. But Blakely v. Washington marked a substantial expansion of the rationale and scope of Apprendi, and threatened to invalidate entire sentencing reform systems, both legally-binding guidelines of the type at issue in Blakely and it's sequel, Booker v. United States, and statutory determinate sentence systems like the one invalidated in Cunningham v. California. Each of these decisions has potential effects not only on sentencing severity and disparity in the cases controlled by that decision, but also on prosecutorial, legislative, and sentencing commission measures designed to comply with the decision, avoid it, and/or mitigate its impact. Field resistance and avoidance measures are likely to be stronger in jurisdictions where the existing sentencing system enjoyed broad support; in such jurisdictions, resistance may be particularly strong to the more controversial Blakely ruling. Impact assessments must therefore carefully distinguish the separate impacts of Apprendi and Blakely in each jurisdiction being studied, and the extent of support for the existing sentencing system. Such assessments should also examine pre-existing trends and other independent sources of change; leadership by sentencing commissions or other officials in crafting responsive measures; structural and other features of the sentencing system which render compliance more or less difficult; and second-stage effects, on sentencing, prosecutorial, or sentencing policy decisions, that reflect the prior compliance, avoidance, and mitigation measures adopted in that jurisdiction. The greatest long-term effects may be on prosecutorial, legislative, and commission decisions, rather than on sentencing outcomes. [source] Flow cytometric measurement of circulating endothelial cells: The effect of age and peripheral arterial disease on baseline levels of mature and progenitor populationsCYTOMETRY, Issue 2 2006Rebecca Gusic Shaffer Abstract Background: Age and cardiovascular disease status appear to alter numbers and function of circulating endothelial progenitor cells (EPCs). Despite no universal phenotypic definition, numerous studies have implicated progenitors with apparent endothelial potential in local responses to vascular injury and with cardiovascular disease in general. To further define the role of this lineage in peripheral artery disease (PAD), we developed a multiparameter flow cytometry assay to analyze multiple phenotypic definitions of progenitor cells (PCs), EPCs, and mature endothelial cells (ECs) and evaluate effects of age and PAD on baseline levels of each subset. Methods: Blood was collected from young healthy subjects (N = 9, mean age 33 ± 8 years), older healthy subjects (N = 13, mean age 66 ± 8 years), and older subjects with PAD (N = 15, mean age 69 ± 8 years). After ammonium chloride lysis, cells were stained and analyzed on a Becton-Dickinson LSR II with a 5-color antibody panel: FITC-anti-CD31, PE-anti-CD146, PE-anti-CD133, PerCP-Cy5.5-anti-CD3,-CD19,-CD33 (lineage panel), PE-Cy7-anti-CD34, and APC-anti-VEGF-R2. Viability was assessed by propidium iodide exclusion, and only viable, low to medium side scatter lineage-negative singlets were analyzed. In some studies, cells were sorted for morphological studies. Subsets were defined as indicated later. Results: Our results, using a comprehensive flow cytometric panel, indicate that CD133+, CD34+, and CD133+/CD34+ PCs are elevated in younger healthy individuals compared to older individuals, both healthy and with PAD. However, the number of EPCs and mature ECs did not significantly differ among the three groups. Assessment of endothelial colony forming units and dual acLDL-lectin staining supported the flow cytometric findings. Conclusions: We describe a comprehensive flow cytometric method to detect circulating mature and progenitor endothelial populations confirmed by conventional morphological and functional assays. Our findings suggest that aging may influence circulating levels of PCs, but not EPCs or ECs; PAD had no effect on baseline levels of any populations investigated. This study provides the basis for evaluating the potential effects of acute stress and therapeutic intervention on circulating progenitor and endothelial populations as a biomarker for cardiovascular status. © 2005 International Society for Analytical Cytology [source] Measurement error: implications for diagnosis and discrepancy models of developmental dyslexiaDYSLEXIA, Issue 3 2005Sue M. Cotton Abstract The diagnosis of developmental dyslexia (DD) is reliant on a discrepancy between intellectual functioning and reading achievement. Discrepancy-based formulae have frequently been employed to establish the significance of the difference between ,intelligence' and ,actual' reading achievement. These formulae, however, often fail to take into consideration test reliability and the error associated with a single test score. This paper provides an illustration of the potential effects that test reliability and measurement error can have on the diagnosis of dyslexia, with particular reference to discrepancy models. The roles of reliability and standard error of measurement (SEM) in classic test theory are also briefly reviewed. This is followed by illustrations of how SEM and test reliability can aid with the interpretation of a simple discrepancy-based formula of DD. It is proposed that a lack of consideration of test theory in the use of discrepancy-based models of DD can lead to misdiagnosis (both false positives and false negatives). Further, misdiagnosis in research samples affects reproducibility and generalizability of findings. This in turn, may explain current inconsistencies in research on the perceptual, sensory, and motor correlates of dyslexia. Copyright © 2005 John Wiley & Sons, Ltd. [source] Geographic body size gradients in tropical regions: water deficit and anuran body size in the Brazilian CerradoECOGRAPHY, Issue 4 2009Miguel Á. Olalla-Tárraga A recent interspecific study found Bergmann's size clines for Holarctic anurans and proposed an explanation based on heat balance to account for the pattern. However, this analysis was limited to cold temperate regions, and exploring the patterns in warmer tropical climates may reveal other factors that also influence anuran body size variation. We address this using a Cerrado anuran database. We examine the relationship between mean body size in a grid of 1° cells and environmental predictors and test the relative support for four hypotheses using an AIC-based model selection approach. Also, we considered three different amphibian phylogenies to partition the phylogenetic and specific components of the interspecific variation in body size using a method analogous to phylogenetic eigen vector regression (PVR). To consider the potential effects of spatial autocorrelation we use eigenvector-based spatial filters. We found the largest species inhabiting high water deficit areas in the northeast and the smallest in the wet southwest. Our results are consistent with the water availability hypothesis which, coupled with previous findings, suggests that the major determinant of interspecific body size variation in anurans switches from energy to water towards the equator. We propose that anuran body size gradients reflect effects of reduced surface to volume ratios in larger species to control both heat and water balance. [source] Gall wasps and their parasitoids in cork oak fragmented forestsECOLOGICAL ENTOMOLOGY, Issue 1 2007GUILLEM CHUST Abstract 1.,This paper explores the potential effects of host-plant fragmentation on cork oak gall wasp populations (Cynipidae, Hymenoptera) and on their predators, lethal inquilines, and parasitoids. To address this objective, galls were collected across a gradient of cork oak (Quercus suber) forest fragmentation in the East Pyrenees (Albera, Spain), and they were incubated to obtain the parasitism rates. 2.,Two hypotheses were tested: (1) Host-plant fragmentation may induce a decline in gall wasp populations because of area and isolation effects on local extinction and dispersal; as a consequence of that, parasitoids may decline even more strongly in fragmented habitats than their prey. (2) Host-plant fragmentation may cause a decline in gall wasp parasitoid populations that, in turn, can lead to an ecological release in their prey populations. 3.,Among the eight cork oak gall wasps sampled in the study area of Albera, the gall abundances of three species (Callirhytis glandium, Callirhytis rufescens, and Andricus hispanicus) were significantly related to forest fragmentation. The overall abundance of gall wasps was affected by a radius of , 890 m surrounding landscape, presenting constant abundances with forest loss until forest cover is reduced at , 40%; below that value the abundance increased rapidly. Three inquilines and 23 parasitoids species were recorded after gall incubation. In 25 cases, species of inquilines and parasitoids were newly recorded for the corresponding host in the Iberian peninsula. 4.,Although the overall parasitism rate was high (1.1), it was uncorrelated with fragmentation and with overall cynipid abundance. These results indicate that host-plant fragmentation was correlated with higher abundance of gall wasps, whereas the parasitism rate could not explain this hyper-abundance in small forest fragments. [source] Ten years after the United Nations General Assembly Special Session (UNGASS): assessing drug problems, policies and reform proposalsADDICTION, Issue 4 2009Peter Reuter ABSTRACT In 1998 the United Nations General Assembly Special Session resolved that governments would reduce drug production and consumption greatly within 10 years. With that period now elapsed, there is an interest in reviewing how successful this was and considering how drug policy could be improved. The demand for drugs in the world has stabilized mainly as a result of the interaction of epidemic forces, culture and economic development. Supply has become more concentrated and the menu of drugs has changed surprisingly slowly. Drug policy is shifting to a more explicitly tolerant configuration in Europe and a few other countries, but retains its ferocity in most of the world. The most prominent innovations under discussion have limited potential effects (heroin maintenance), have as yet been unproductive of policy interventions (,addiction is a brain disease') or have no political appeal (legalization). The option with the most scope is increased effort at diverting arrested drug users out of criminal justice systems. No prevention, treatment or enforcement strategies have demonstrated an ability to substantially affect the extent of drug use and addiction. The best that government interventions can do is to reduce the damaging consequences of drug use and drug control. More attention should be given to reductions in the intensity of drug enforcement, which has many unintended adverse consequences and yields few of the claimed gains. [source] Endogenous estrogen status, but not genistein supplementation, modulates 7,12-dimethylbenz[a]anthracene-induced mutation in the liver cII gene of transgenic big blue rats,ENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 5 2005Tao Chen Abstract A growing number of studies suggest that isoflavones found in soybeans have estrogenic activity and may safely alleviate the symptoms of menopause. One of these isoflavones, genistein, is commonly used by postmenopausal women as an alternative to hormone replacement therapy. Although sex hormones have been implicated as an important risk factor for the development of hepatocellular carcinoma, there are limited data on the potential effects of the estrogens, including phytoestrogens, on chemical mutagenesis in liver. Because of the association between mutation induction and the carcinogenesis process, we investigated whether endogenous estrogen and supplemental genistein affect 7,12-dimethylbenz[a]anthracene (DMBA)-induced mutagenesis in rat liver. Intact and ovariectomized female Big Blue rats were treated with 80 mg DMBA/kg body weight. Some of the rats also received a supplement of 1,000 ppm genistein. Sixteen weeks after the carcinogen treatment, the rats were sacrificed, their livers were removed, and mutant frequencies (MFs) and types of mutations were determined in the liver cII gene. DMBA significantly increased the MFs in liver for both the intact and ovariectomized rats. While there was no significant difference in MF between the ovariectomized and intact control animals, the mutation induction by DMBA in the ovariectomized groups was significantly higher than that in the intact groups. Dietary genistein did not alter these responses. Molecular analysis of the mutants showed that DMBA induced chemical-specific types of mutations in the liver cII gene. These results suggest that endogenous ovarian hormones have an inhibitory effect on liver mutagenesis by DMBA, whereas dietary genistein does not modulate spontaneous or DMBA-induced mutagenesis in either intact or ovariectomized rats. Environ. Mol. Mutagen., 2005. Published 2005 Wiley-Liss, Inc. [source] Direct and indirect effects of a potential aquatic contaminant on grazer,algae interactionsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2009Michelle A. Evans-White Abstract Contaminants have direct, harmful effects across multiple ecological scales, including the individual, the community, and the ecosystem levels. Less, however, is known about how indirect effects of contaminants on consumer physiology or behavior might alter community interactions or ecosystem processes. We examined whether a potential aquatic contaminant, an ionic liquid, can indirectly alter benthic algal biomass and primary production through direct effects on herbivorous snails. Ionic liquids are nonvolatile organic salts being considered as an environmentally friendly potential replacement for volatile organic compounds in industry. In two greenhouse experiments, we factorially crossed four concentrations of 1-N-butyl-3-methylimidazolium bromide (bmimBr; experiment 1: 0 or 10 mg/L; experiment 2: 0, 1, or 100 mg/L) with the presence or absence of the snail Physa acuta in aquatic mesocosms. Experimental results were weighted by their respective control (no bmimBr or P. acuta) and combined for statistical analysis. When both bmimBr and snails were present, chlorophyll a abundance and algal biovolume were higher than would be expected if both factors acted additively. In addition, snail growth rates, relative to those of controls, declined by 41 to 101% at 10 and 100 mg/L of bmimBr. Taken together, these two results suggest that snails were less efficient grazers in the presence of bmimBr, resulting in release of algae from the grazer control. Snails stimulated periphyton primary production in the absence, but not in the presence, of bmimBr, suggesting that bmimBr also can indirectly alter ecosystem function. These findings suggest that sublethal contaminant levels can negatively impact communities and ecosystem processes via complex interactions, and they provide baseline information regarding the potential effects of an emergent industrial chemical on aquatic systems. [source] Impacts of aircraft deicer and anti-icer runoff on receiving waters from Dallas/Fort worth International Airport, Texas, USAENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2006Steven R. Corsi Abstract From October 2002 to April 2004, data were collected from Dallas/Fort Worth (DFW) International Airport (TX, USA) outfalls and receiving waters (Trigg Lake and Big Bear Creek) to document the magnitude and potential effects of aircraft deicer and anti-icer fluid (ADAF) runoff on water quality. Glycol concentrations at outfalls ranged from less than 18 to 23,800 mg/L, whereas concentrations in Big Bear Creek were less because of dilution, dispersion, and degradation, ranging from less than 18 to 230 mg/L. Annual loading results indicate that 10 and 35% of what was applied to aircraft was discharged to Big Bear Creek in 2003 and 2004, respectively. Glycol that entered Trigg Lake was diluted and degraded before reaching the lake outlet. Dissolved oxygen (DO) concentrations at airport outfalls sometimes were low (<2.0 mg/L) but typical of what was measured in an urban reference stream. In comparison, the DO concentration at Trigg Lake monitoring sites was consistently greater than 5.5 mg/L during the monitoring period, probably because of the installation of aerators in the lake by DFW personnel. The DO concentration in Big Bear Creek was very similar at sites upstream and downstream of airport influence (>5.0 mg/L). Results of toxicity tests indicate that effects on Ceriodaphnia dubia, Pimephales promelas, and Selanastrum capricornutum are influenced by type IV ADAF (anti-icer), not just type I ADAF (deicer) as is more commonly assumed. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||