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Adverse Environmental Conditions (adverse + environmental_condition)
Selected AbstractsProto-professionalism: how professionalisation occurs across the continuum of medical educationMEDICAL EDUCATION, Issue 1 2005Sean R Hilton Introduction, Professionalism and its assessment across the medical education continuum have become prominent topics in recent years. We consider the nature of professionalism and how it emerges and relates to the work carried out by doctors and doctors-in-training. Thesis and Discussion, We suggest 6 domains in which evidence of professionalism can be expected: ethical practice; reflection/self-awareness; responsibility for actions; respect for patients; teamwork, and social responsibility. Furthermore, we propose that a defining characteristic is encapsulated by the Greek term phronesis, or practical wisdom. Phronesis is acquired only after a prolonged period of experience (and reflection on experience) occurring in concert with the professional's evolving knowledge and skills base. The prior period we have termed as one of ,proto-professionalism'. Influences on proto-professionalism are considered in terms of moral and psychosocial development and reflective judgement. Conclusion, Curricula that develop meta-skills will foster the acquisition and maintenance of professionalism. Adverse environmental conditions in the hidden curriculum may have powerful attritional effects. [source] Subcellular distribution of key enzymes of lipid metabolism during the euthermia-hibernation-arousal cycleJOURNAL OF ANATOMY, Issue 6 2009Anna Suozzi Abstract Mammalian hibernation is a natural, fully reversible hypometabolic state characterized by a drastic reduction of body temperature and metabolic activity, which ensures survival to many species under adverse environmental conditions. During hibernation, many hibernators rely for energy supply almost exclusively on lipid reserves; the shift from carbohydrate to lipid metabolism implies profound rearrangement of the anabolic and catabolic pathways of energetic substrates. However, the structural counterpart of such adaptation is not known. In this study we investigated, by using immunoelectron microscopy, the fine intracellular distribution of two key enzymes involved in lipid metabolism, namely, the fatty acid synthase (FAS) and the long-chain fatty acyl-CoA synthetase (ACSL), in hepatocytes of euthermic, hibernating and arousing hazel dormice. Our results show that the two enzymes are differentially distributed in cellular compartments (cytoplasm, mitochondria and cell nuclei) of hepatocytes during euthermia. Quantitative redistribution of both enzymes among cellular compartments takes place during hibernation and arousal, in accordance with the physiological changes. Interestingly, this redistribution follows different seasonal patterns in cytoplasm, mitochondria and nuclei. In conclusion, our data represent the first quantitative morphological evidence of lipid enzyme distribution in a true hibernator throughout the year cycle, thus providing a structural framework to biochemical changes associated with the hypometabolism of hibernation. [source] Population stability in salmon species: effects of population size and female reproductive allocationJOURNAL OF ANIMAL ECOLOGY, Issue 5 2003Sigurd Einum Summary 1Population stability (i.e. level of temporal variation in population abundance) is linked commonly to levels of environmental disturbances. However, populations may also differ in their propensity to dampen or amplify the effects of exogenous forces. Here time-series of population estimates were used to test for such differences among 104 populations of six salmon species. 2At the species level, Atlantic (Salmo salar L.), chinook (Oncorhynchus tshawytscha Walbaum) and coho salmon (O. kisutch W) were less variable than sockeye (O. nerka W) and pink salmon (O. gorbuscha W). Chum salmon (O. keta W) was more similar to sockeye and pink salmon. These differences may be related in part to differences in body size, and hence susceptibility to adverse environmental conditions, at the time when they migrate to the sea or lakes. 3At the population level no effect of fecundity on variability was found, in contrast to findings for marine fishes, nor of egg size. Whereas substantial differences in the temporal stability of environmental factors among geographically close populations may over-ride any effects of fecundity or egg size in fresh water, this is less likely in the marine environment where spatial autocorrelations of environmental variability are more pronounced. 4Variation in population sizes was related positively to the duration of time-series when using standard deviations of ln-transformed population estimates, and also when using linearly detrended population variation, suggesting non-linear long-term abundance trends in salmon populations that extend beyond the 7-year period of the shortest time-series. 5When controlling for differences among species, stability increased with increasing population size, and it is hypothesized that this is due to large populations having a more complex spatial and genetic structure than small populations due to wider spatial distribution. The effects of population size on stability, as well as differences in stability among species, suggest that population- and organism-specific characteristics may interact with exogenous forces to shape salmon population dynamics. [source] Manipulating rearing conditions reveals developmental sensitivity in the smaller sex of a passerine bird, the European starling Sturnus vulgarisJOURNAL OF AVIAN BIOLOGY, Issue 5 2007Eloise Rowland Traditionally, studies of sexually size-dimorphic birds and mammals report that the larger sex is more sensitive to adverse environmental conditions during ontogeny. However, recent studies in avian species that exhibit moderate size-dimorphism indicate that the smaller sex may be more sensitive to poor rearing conditions. To better understand sex-specific sensitivity in a passerine exhibiting moderate size-dimorphism, we examined growth, cell-mediated immunity (CMI) and survival of European starling Sturnus vulgaris nestlings following an experimental reduction of maternal rearing ability (via a feather-clipping manipulation). Contrary to conventional theory, daughters showed reduced growth in both body mass and measures of structural size in response to the maternal treatment. In contrast, sons showed no reductions in any of these traits in relation to the treatment. No sex-specific differences in nestling CMI were found for either group, although CMI of nestlings raised by manipulated mothers were higher than those of control nestlings. Finally, fledging sex ratios did not change from those at hatching indicating that neither sex appeared differentially sensitive to the maternal treatment in terms of mortality. These results reveal that variation in the quality of the rearing environment can have significant effects on the smaller sex of a passerine exhibiting moderate dimorphism and as such support recent studies of species with small-moderate sexual size-dimorphism. Combined results suggest that sex-specific effects of environmental variation on nestling development may be both context- (i.e., brood size, resource level, hatching order) and temporally- (when during development they occur) specific. Furthermore, more studies are needed that examine multiple traits at several developmental stages and then follow the sexes over the longer-term to examine potential effects on fitness. [source] Performance of laser and radar ranging devices in adverse environmental conditionsJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 9 2009Julian Ryde A comparative evaluation of millimeter-wave radar and two-dimensional scanning lasers in dust and rain conditions for sensor applications in field robotics is presented. A robust and reliable method for measuring the level of suspended dust (or other obscurant media) by determining the transmission coefficient is developed and used for quantitative assessment of sensor performance. The criteria of target acquisition reliability, precision, and accuracy under varying environmental conditions are assessed via sensor operation in a controlled environment. This environment generated dust and rain of varying densities. Sensor performance is also assessed for the potential effect on digital terrain mapping and haul truck localization due to sensor-specific behaviors in these conditions (e.g., false targets, increased noise). Trials on a research electric face shovel are conducted to test observed behaviors. It is concluded that laser scanners are suitable for environments with transmissions exceeding 92%,93%/m for targets closer than 25 m. The radar remained relatively unaffected by the generated conditions of rain (50,70 mm/h) and dust (10-m visibility); however, its accuracy (0.1 m with a corner reflector and 0.3 m on a haul truck), free-space clutter, and scan rate were insufficient for locating unmodified haul trucks for this application. © 2009 Wiley Periodicals, Inc. [source] Critical habitat during the transition from maternal provisioning in freshwater fish, with emphasis on Atlantic salmon (Salmo salar) and brown trout (Salmo trutta)JOURNAL OF ZOOLOGY, Issue 4 2006J. D. Armstrong Abstract In freshwater fish, the transition from dependence on maternal yolk reserves to independent foraging can be an early critical period, with survival during this stage having a strong influence on population abundance and cohort strength. Information concerning Atlantic salmon Salmo salar and brown trout Salmo trutta as model species is reviewed to show how population dynamics are influenced by habitat use during the transitional stage and illustrate the role of maternal provisioning along with density-dependent and -independent factors. The allocation of resources in yolk and timing and position of spawning strongly influence the biotic and abiotic environments of juveniles and their subsequent performance. Vulnerability to predators, adverse environmental conditions and restricted conditions over which they can successfully forage result in specific habitat requirements for newly independent juveniles. The availability of slow-flowing habitats at stream margins during the first month of independence is crucial. Alteration of natural flow regimes and physical habitat structure, associated with a wide range of anthropogenic influences, can have significant deleterious effects on the availability of critical juvenile habitat. A model combining habitat structure and the relationship between density-dependent and -independent mortality is presented to explore the range of conditions under which the transitional period would have a strong influence on population abundance. This model provides a framework for establishing thresholds or optima for habitat availability that will favour sufficient recruitment out of the transitional stage. Using the modelling framework, managers can make informed decisions on the utility and cost effectiveness of fisheries and habitat management activities designed to increase juvenile survival during the transition to independence. A range of management options is outlined for improving habitat quality and increasing juvenile survival during the transitional period, including restoration of structural complexity, provision of suitable flow regimes, and tailoring stocking and reintroduction strategies to mimic natural dynamics. [source] Evolution of reproductive seasonality in bearsMAMMAL REVIEW, Issue 1 2007THOMAS J. SPADY ABSTRACT 1Of the eight species of Ursidae, six are currently at risk of extinction and the remainder face significant risks to their future survival. One of the greatest threats to bears is human-imposed environmental alteration (e.g. global warming, chemical pollutants, deforestation). An examination of the reproductive biology and phylogeny of the Ursidae reveals reproductive seasonality as a probable adaptation to adverse environmental conditions. 2Seven of the eight extant species exhibit distinct mating and birth seasons, with the most ancient species evolving facultative seasonality as an adaptation to the increasingly seasonal climate of the Pliocene. The remainder of the extant species evolved during the Pleistocene glaciations, under conditions of severe seasonal food restriction. Under these conditions, an obligate mode of seasonality emerged and persists to the present. 3Knowledge of the natural history of seasonal reproduction in the ursids and how it evolved in response to global climatic change provides a context for understanding the ramifications of current environmental change on the reproduction of these important species. [source] The role of abscisic acid and auxin in the response of poplar to abiotic stressPLANT BIOLOGY, Issue 2 2010J. Popko Abstract The plant hormones auxin and abscisic acid may at first sight appear to be a conflicting pair of plant regulators. Abscisic acid content increases during stress and protects plant water status. The content of free auxin in the developing xylem of poplar declines during stress, while auxin conjugates increase. This indicates that specific down-regulation of a signal transduction chain is important in plant adaptation to stress. Diminished auxin content may be a factor that adapts growth and wood development of poplar during adverse environmental conditions. To allow integration of environmental signals, abscisic acid and auxin must interact. Data are accumulating that abscisic acid,auxin cross-talk exists in plants. However, knowledge of the role of plant hormones in the response of trees to stress is scarce. Our data show that differences in the localisation of ABA synthesis exist between the annual, herbaceous plant Arabidopsis and the perennial woody species, poplar. [source] Insect-symbiont systems: From complex relationships to biotechnological applicationsBIOTECHNOLOGY JOURNAL, Issue 12 2009Sandra Chaves Abstract Microbial symbiosis is a ubiquitous aspect of life and was a major element in the ability of insects to explore several adverse environments. To date, the study of symbiosis in insects has been impaired by the unculturability of most symbionts. However, some molecular methods represent powerful tools to help understand insect-microorganism associations and to disclose new symbiont-host systems. Beyond playing an essential role in nutrition and development of the insects, symbionts can produce bioactive compounds that protect the host against adverse environmental conditions, predators and/or direct competitors. Since the search for natural bioactive products and new enzymes is a developing area, understanding the diversity and nature of symbiont-host relationships paves the way for the exploitation of new resources in biotechnology. Furthermore, genetic transformation of the symbionts with genes that code for compounds that are toxic for pathogenic and phytopathogenic agents is also a promising area of application of the insect-symbiont relationships. The search for new bioactive compounds, the use of symbionts for pest and disease control and the molecular strategies applied for these purposes are issues of particular interest for innovative biotechnological applications and are addressed in the present review. [source] Effect of disaccharides on the stabilization of bovine trypsin against detergent and autolysisBIOTECHNOLOGY PROGRESS, Issue 3 2010Shivcharan Prasad Abstract Osmolytes have been reported to stabilize biomolecules and even whole organisms against exposure to adverse environmental conditions. In this work, we report for the first time the use of some of these osmolytes, viz., the disaccharides trehalose and sucrose, in the stabilization of bovine trypsin against exposure to the anionic detergent sodium dodecyl sulfate and autolysis. Exposure of trypsin to SDS at a molar ratio of 1:45 led to decrease in trypsin activity by 61%. In the presence of 1 M sucrose and 1 M trehalose, the residual trypsin activity was found to increase to that of original enzyme activity. These two disaccharides were also found to slow down the rate of autolysis, resulting in residual activities of 80 and 88%, respectively, after incubation for 24 h. Active site titration showed retention of the fraction of active sites in the presence of trehalose. Fluorescence and CD spectroscopies were used to decipher the probable mechanism of this protective role of the disaccharides. Although complete resumption of secondary structure was not seen in the presence of the two disaccharides, the spectra of trypsin in the presence of stabilizers resembled the spectrum of native trypsin and were significantly different from the spectrum of detergent-denatured enzyme. Correlating the data obtained from spectroscopy with those obtained from activity assay, we propose that the retention of secondary structure of the enzyme is largely responsible for the retention of the functionally active form of trypsin. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] Dry Season Den Use by Pygmy Spotted Skunk (Spilogale pygmaea) in a Tropical Deciduous Forest of MexicoBIOTROPICA, Issue 3 2009Lisette Cantú-Salazar ABSTRACT Dry season den use by the pygmy spotted skunk Spilogale pygmaea, an endemic and threatened species of western Mexico, was evaluated at the micro and macrohabitat level, in the tropical deciduous forest of Chamela, Jalisco, Mexico. During the dry seasons of 1997, 1998, and 2000, 79 skunk den sites (29 for females and 50 males) were located using Radiotelemetry. Dens were underground excavations with one to five access points, located mostly on open ground or under live or dead trees. Skunks exhibited a continued reuse of dens but evidence of simultaneous occupation by two or more skunks was not found. Microhabitat den-site analysis showed that skunks showed flexibility and individual variation in usage of the microhabitat surrounding den sites inside the forest. Macrohabitat den-site analysis showed that skunks were not selecting either tropical deciduous or tropical semideciduous forest; however, no dens were located outside the forest in transformed habitats, strengthening the hypothesis of the association of this species with the tropical deciduous forests on the Pacific coast of Mexico. The current deforestation rates of the tropical deciduous forest in the coast of Jalisco could be reducing the potential den sites for pygmy spotted skunks and exposing them to adverse environmental conditions and predation. RESUMEN El zorrillo pigmeo (Spilogale pygmaea) es una especie endémica del oeste de México y considerada en peligro de extinción. Estudiamos el uso de madrigueras por parte del zorrillo pigmeo a nivel de micro y macrohabitat durante la época seca en el bosque tropical deciduo de Chamela, Jalisco, México. Durante las época seca de 1997, 1998 y 2000 localizamos un total de 79 madrigueras de zorrillo pigmeo utilizando telemetría (29 pertenecientes a hembras y 50 a machos). Las madrigueras fueron excavaciones subterráneas con uno a cinco accesos localizadas en áreas el suelo o bajo árboles vivos o muertos probablemente construidas por otras especies y ocupadas por los zorrillos pigmeos. Los zorrillos mostraron que los zorrillos en varias ocasiones cada una de las madrigueras, pero no encontramos evidencia de ocupación simultánea de una madriguera por más de un zorrillo pigmeo. El análisis a nivel microhabitat mostró que los zorrillos pigmeos utilizan madrigueras al interior del bosque pero presentaban una gran flexibilidad en cuanto al uso del hábitat a este nivel con un elevado nivel de variación individual. A nivel macrohabitat no encontramos selección por parte de los zorrillos para colocar sus madrigueras en el bosque tropical deciduo o el bosque tropical semideciduo, sin embargo no se encontraron madrigueras en áreas fuera del bosque. Esta observación sugiere que los zorrillos pigmeos presentan una fuerte asociación a las áreas de bosque tropical de la costa del Pacifico mexicano. Las elevadas tasas de deforestación de los bosques tropicales en la costa de Jalisco, podrían reducir la existencia de sitios potenciales para madrigueras de zorrillo pigmeo, exponiéndolos probablemente a condiciones ambientales adversas y depredación. [source] Facial skin fluorescence as a marker of the skin's response to chronic environmental insults and its dependence on ageBRITISH JOURNAL OF DERMATOLOGY, Issue 1 2006G.N. Stamatas Summary Background, Throughout life facial skin is exposed to a variety of adverse environmental conditions and is constantly required to repair itself. The rate of epidermal cell proliferation is indicative of the skin's repair rate and can be monitored noninvasively in vivo using skin intrinsic fluorescence markers. Objectives, The goal of the present study was to assess the effects of ageing, geographical region, ethnic origin and season on the ability of facial skin to repair itself in the presence of chronic environmental insults using in vivo fluorescence spectroscopy. Methods, Skin fluorescence emission was measured on the cheeks of 522 individuals in winter and repeated in summer in five different geographical locations in the Asia-Pacific region. Fluorescence emission was also measured from 80 caucasians of fair complexion in the United States (New Jersey area) on the face and on a relatively protected area (upper inner arm). The age range of the participants was 14,75 years. Results, We found that epidermal proliferation rates decrease monotonically with age, while the fluorescence of collagen and elastin cross-links increases with age indicating accumulation of advanced glycation end-products. These trends were independent of geographical region, ethnic origin and season of measurement. Epidermal proliferation rates of facial skin were higher than those of unexposed sites; they may be 10 times higher in younger (second decade) than in older (seventh decade) individuals, and they decrease with age at rates 10 times faster compared with those of unexposed sites. Conclusions, This is the first time that epidermal proliferation and its dependence on ageing have been measured noninvasively on the human face. The higher tryptophan fluorescence values on the face vs. the protected site are indicative of accelerated rates of epidermal proliferation in the presence of chronic environmental insults. The repair potential of facial skin, i.e. its ability to maintain high proliferation rates, is maximal in younger populations and gradually decreases with age. [source] | ||||||||||||||||||||||