			Home About us Contact

Greater Potential (greater + potential)

Distribution by Scientific Domains

Life Sciences	42%
Medical Sciences	26%
Engineering	7%
6 Other Domains	25%

Distribution within Life Sciences

Ecology & Organismal Biology	26%
Conservation Science	16%

Selected Abstracts

Economic Growth and Biodiversity Loss in an Age of Tradable Permits

CONSERVATION BIOLOGY, Issue 4 2006
JON ROSALES
comercio de emisiones; límite y comercio; proceso ciencia-política; Protocolo de Kyoto Abstract:,Tradable permits are increasingly becoming part of environmental policy and conservation programs. The efficacy of tradable permit schemes in addressing the root cause of environmental decline,economic growth,will not be achieved unless the schemes cap economic activity based on ecological thresholds. Lessons can be learned from the largest tradable permit scheme to date, emissions trading now being implemented with the Kyoto Protocol. The Kyoto Protocol caps neither greenhouse gas emissions at a level that will achieve climate stability nor economic growth. If patterned after the Kyoto Protocol, cap-and-trade schemes for conservation will not ameliorate biodiversity loss either because they will not address economic growth. In response to these failures to cap economic growth, professional organizations concerned about biodiversity conservation should release position statements on economic growth and ecological thresholds. The statements can then be used by policy makers to infuse these positions into the local, national, and international environmental science-policy process when these schemes are being developed. Infusing language into the science-policy process that calls for capping economic activity based on ecological thresholds represents sound conservation science. Most importantly, position statements have a greater potential to ameliorate biodiversity loss if they are created and released than if this information remains within professional organizations because there is the potential for these ideas to be enacted into law and policy. Resumen:,Cada vez más, los permisos comerciables son parte de la política ambiental y de los programas de conservación. La eficacia de los esquemas de permisos comerciables para atender la causa principal de la declinación ambiental,crecimiento económico,será baja a menos que los esquemas limiten la actividad económica con base en umbrales ecológicos. Se pueden aprender lecciones del mayor esquema de permisos comerciables a la fecha, la comercialización de emisiones implementada con el Protocolo de Kyoto. El Protocolo de Kyoto no limita a las emisiones de gases a un nivel que logre la estabilidad climática ni al crecimiento económico. Si se sigue el modelo del Protocolo de Kyoto, los esquemas de límite y comercio tampoco reducirán las pérdidas de biodiversidad porque no considerarán al crecimiento económico. En respuesta a estas fallas para limitar el crecimiento económico, las organizaciones profesionales preocupadas por la conservación de la biodiversidad deberían emitir declaraciones sobre su posición respecto a umbrales ecológicos y de crecimiento económico. Las declaraciones luego pueden ser usadas por políticos para infundir estas posiciones en el proceso ciencia ambiental-política a nivel local, nacional e internacional cuando estos esquemas estén siendo desarrollados. La infusión de lenguaje que demanda la limitación de actividades de crecimiento económico con base en umbrales ecológicos es ciencia de la conservación sólida. Más notablemente, las declaraciones de posición tienen un mayor potencial para reducir las pérdidas de biodiversidad si son creadas y publicadas que si esta información permanece dentro de las organizaciones profesionales porque existe el potencial para que estas ideas se constituyan en leyes y políticas. [source]

Form,flow interactions of an aeolian saucer blowout

EARTH SURFACE PROCESSES AND LANDFORMS, Issue 7 2009
Chris H. Hugenholtz
Abstract Airflow patterns through a saucer blowout are examined from wind speed and direction measurements made during a chinook wind event. The blowout long-axis is oriented east,west with a broad depositional apron on the east side. Wind directions during the event rotated from south-westerly to westerly, permitting an assessment of oblique and axis-parallel flows. Results show that airflow passing over the windward rim of the saucer blowout expands and decelerates, leading to flow separation and a small re-circulation zone on sheltered lee slopes. Near the deflation basin, airflow re-attaches to the blowout surface and accelerates up to a small opening in the east rim, where it can be up to 50% faster than on the windward edge. Beyond the downwind rim the airflow expands and decelerates and sand is deposited onto a broad apron. Similar to coastal trough blowouts, the degree of airflow steering and acceleration along the deflation basin is determined by the angle of incidence between the approach wind and the long-axis of the blowout. As the angle of incidence increases wind speed accelerates at 0·3 m above the surface of the deflation basin and the degree of airflow steering increases. Overall, a two-fold process is identified, where south-westerly flows have greater potential for eroding the deflation basin, while westerly flows have greater potential for evacuating sand from within the blowout. Visual observations indicate that sand eroded from the deflation basin during south-westerly flows is re-distributed to adjacent zones of low wind speed until axis-parallel winds evacuate the sand through the opening in the east rim. Morphometric changes since 1994 indicate that the blowout morphology has remained relatively constant, suggesting a persistent interplay between oblique and axis-parallel wind erosion events. Collectively, these findings indicate that the angle of approach winds is an important control on saucer blowout morphodynamics. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Assessing the potential for fish predation to impact zebra mussels (Dreissena polymorpha): insight from bioenergetics models

ECOLOGY OF FRESHWATER FISH, Issue 2 2004
M. A. Eggleton
Abstract,,, Rates of annual food consumption and biomass were modeled for several fish species across representative rivers and lakes in eastern North America. Results were combined to assess the relative potential of fish predation to impact zebra mussels (Dreissena polymorpha). Predicted annual food consumption by fishes in southern waters was over 100% greater than that in northern systems because of warmer annual water temperatures and presumed increases in metabolic demand. Although generally increasing with latitude, biomasses of several key zebra mussel fish predators did not change significantly across latitudes. Biomasses of some less abundant fish predators did increase significantly with latitude, but increases were not of the magnitude to offset predicted decreases in food consumption. Our results generally support the premise that fishes in rivers and lakes of the southern United States (U.S.) have inherently greater potential to impact zebra mussels by predation. Our simulations may provide a partial explanation of why zebra mussel invasions have not been as rapid and widespread in southern U.S. waters compared to the Great Lakes region. Resumen 1Modelamos la tasa de consumo anual de alimento y biomasa para varias especies de peces en una muestra representativa de ríos y lagos del este de Norte América. Combinamos los resultados para evaluar el potencial relativo que estas especies de peces pueden ejercer sobre la abundancia del mejillón asiático Dreissena polymorpha. Las predicciones sobre consumo para peces en lagos y ríos del sur fueron más del 100% comparadas con sistemas septentrionales. Esto se puede deber a las temperaturas anuales más altas y aumentos en la demanda metabólica de peces en ríos y lagos del sur de Norte América. 2La biomasa de varias especies claves de peces que consumen D. polymorpha no cambió apreciablemente con latitud. La biomasa de algunos peces que consumen D. polymorpha aumentó significativamente con latitud, pero este aumento no era de una magnitud suficiente para compensar la disminución en el consumo de alimento. 3Nuestros resultados apoyan generalmente la premisa de que los peces en ríos y lagos del sur de los Estados Unidos (EE.UU.) tienen un potencial inherente mayor para poder controlar D. polymorpha. Nuestras simulaciones proporcionan una explicación parcial de por qué las invasiones de D. polymorpha no han sido tan rápidas y ampliamente distribuidas en aguas sureñas comparado con la región de los Grandes Lagos. [source]

Crack closure on rehydration of glass-ionomer materials

EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 5 2004
Sharanbir K. Sidhu
Moisture-sensitivity of immature glass-ionomer cements suggests that hydration-induced volumetric expansion might close and potentially heal established cracks. Crack closure in glass-ionomer cements (GICs) was observed following rehydration. Circular cavities were prepared in 15 teeth: 10 were restored with resin-modified GICs (5 with Fuji II LC and 5 with Photac-Fil) and 5 were restored with a conventional GIC (Fuji IX); all were dehydrated for 1 min with air and imaged immediately by confocal microscopy. Crack formation in each was located, after which water was placed on the surface and observed for 15 min via a CCD camera. Dehydration caused cracks with measurable gaps, while rehydration resulted in varying degrees of closure: closure was limited in the conventional GIC, and complete or near complete along part/s of the crack in the resin-modified GICs. In all, closure movement became imperceptible after the first 10 min. Statistical analysis indicated no significant difference between the closure behavior of all materials. However, the resin-modified GICs appeared to show a greater potential for closure of established cracks than the conventional GIC upon rehydration. [source]

ADVERTISEMENT-CALL PREFERENCES IN DIPLOID-TETRAPLOID TREEFROGS (HYLA CHRYSOSCELIS AND HYLA VERSICOLOR): IMPLICATIONS FOR MATE CHOICE AND THE EVOLUTION OF COMMUNICATION SYSTEMS

EVOLUTION, Issue 2 2005
H. Carl Gerhardt
Abstract Signals used for mate choice and receiver preferences are often assumed to coevolve in a lock-step fashion. However, sender-receiver coevolution can also be nonparallel: even if species differences in signals are mainly quantitative, females of some closely related species have qualitatively different preferences and underlying mechanisms. T o-alternative playback experiments using synthetic calls that differed in fine-scale temporal properties identified the receiver criteria in females of the treefrog Hyla chrysoscelis for comparison with female criteria in a cryptic tetraploid species (H. versicolor); detailed preference functions were also generated for both species based on natural patterns of variation in temporal properties. The species were similar in three respects: (1) pulses of constant frequency were as attractive as the frequency-modulated pulses typical of conspecific calls; (2) changes in preferences with temperature paralleled temperature-dependent changes in male calls; and (3) preference functions were unimodal, with weakly defined peaks estimated at values slightly higher than the estimated means in conspecific calls. There were also species differences: (1) preference function slopes were steeper in H. chrysoscelis than in H. versicolor; (2) preferences were more intensity independent in H. chrysoscelis than in H. versicolor; (3) a synergistic effect of differences in pulse rate and shape on preference strength occurred in H. versicolor but not in H. chrysoscelis; and (4) a preference for the pulse shape typical of conspecific calls was expressed at the species-typical pulse duration in H. versicolor but not in H. chrysoscelis. However, females of H. chrysoscelis did express a preference based on pulse shape when tested with longer-than-average pulses, suggesting a hypothesis that could account for some examples of nonparallel coevolution. Namely, preferences can be hidden or revealed depending on the direction of quantitative change in a signal property relative to the threshold for resolving differences in that property. The results of the experiments reported here also predict patterns of mate choice within and between contemporary populations. First, intraspecific mate choice in both species is expected to be strongly influenced by variation in temperature among calling males. Second, simultaneous differences in pulse rate and pulse shape are required for effective species discrimination by females of H. versicolor but not by females of H. chrysoscelis. Third, there is greater potential for sexual selection within populations and for discrimination against calls produced by males in other geographically remote populations in H. chrysoscelis than in H. versicolor. [source]

Linking flux network measurements to continental scale simulations: ecosystem carbon dioxide exchange capacity under non-water-stressed conditions

GLOBAL CHANGE BIOLOGY, Issue 4 2007
KATHERINE E. OWEN
Abstract This paper examines long-term eddy covariance data from 18 European and 17 North American and Asian forest, wetland, tundra, grassland, and cropland sites under non-water-stressed conditions with an empirical rectangular hyperbolic light response model and a single layer two light-class carboxylase-based model. Relationships according to ecosystem functional type are demonstrated between empirical and physiological parameters, suggesting linkages between easily estimated parameters and those with greater potential for process interpretation. Relatively sparse documentation of leaf area index dynamics at flux tower sites is found to be a major difficulty in model inversion and flux interpretation. Therefore, a simplification of the physiological model is carried out for a subset of European network sites with extensive ancillary data. The results from these selected sites are used to derive a new parameter and means for comparing empirical and physiologically based methods across all sites, regardless of ancillary data. The results from the European analysis are then compared with results from the other Northern Hemisphere sites and similar relationships for the simplified process-based parameter were found to hold for European, North American, and Asian temperate and boreal climate zones. This parameter is useful for bridging between flux network observations and continental scale spatial simulations of vegetation/atmosphere carbon dioxide exchange. [source]

Medical journals and effective dissemination of health research

HEALTH INFORMATION & LIBRARIES JOURNAL, Issue 4 2001
Aravinthan Coomarasamy
Clinical medical journals have not been effective in meeting the information needs of practitioners and bridging the gap between clinical research and practice. The slow adoption of results of clinical research is at least partly due to the failure of clinical journals to disseminate information in a way that would motivate practitioners to change practice. Although implementation is primarily a local process, medical journals are in a unique position to advance implementation by modifying their focus and adjusting their contents. Strategies that may be useful include publication of pre-appraised evidence summaries and ,clinical bottom-lines' and giving importance to systematic reviews and large evaluative research articles as they represent higher levels of evidence and have greater potential to change practice. Clinical journals should encourage researchers to consider how and by whom the findings will be used and provide information on implications for implementation such as possible strategies that may work, cost-effectiveness, side-effects and potential barriers to implementation. Medical journal publishers should explore ways to cooperate so that findings of landmark clinical trials could be shared thus reducing the ,scatter' of medical information. Electronic media offers numerous advantages such as quick accessibility and linking of information, and medical journals should capitalize on such innovations. There is a paradigm shift in health care practice as evidence is consciously and explicitly incorporated into individual patient care. Medical journals need to change to reflect this change in practice and provide practitioners with valid and relevant information. [source]

The effect of riparian land use on transport hydraulics in agricultural headwater streams located in northeast Ohio, USA

HYDROLOGICAL PROCESSES, Issue 1 2010
Kyle S. Herrman
Abstract This study examined if riparian land use (forested vs agricultural) affects hydraulic transport in headwater streams located in an agriculturally fragmented watershed. We identified paired 50-m reaches (one reach in agricultural land use and the other in forested land use) along three headwater streams in the Upper Sugar Creek Watershed in northeast Ohio, USA (40° 51,42,N, 81° 50,29,W). Using breakthrough curves obtained by Rhodamine WT slug injections and the one-dimensional transport with inflow and storage model (OTIS), hydraulic transport parameters were obtained for each reach on six different occasions (n = 36). Relative transient storage (AS:A) was similar between both reach types (As: A = 0·3 ± 0·1 for both agricultural and forested reaches). Comparing values of Fmed200 to those in the literature indicates that the effect of transient storage was moderately high in the study streams in the Upper Sugar Creek Watershed. Examining travel times revealed that overall residence time (HRT) and residence time in transient storage (TSTO) were both longer in forested reaches (forested HRT = 19·1 ± 11·5 min and TSTO = 4·0 ± 3·8 min; agricultural HRT = 9·3 ± 5·3 min and TSTO = 1·7 ± 1·4 min). We concluded that the effect of transient storage on solute transport was similar between the forested and agricultural reaches but the forested reaches had a greater potential to retain solutes as a result of longer travel times. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Conceptions of aggression and withdrawal in early childhood

INFANT AND CHILD DEVELOPMENT, Issue 5 2004
Jessica W. Giles
Abstract Two studies investigate young children's beliefs about aggression and withdrawal in others with reference to the possibility of stability and change. Study 1 (N=41) provides evidence that preschool children (1) view aggression in more essentialist ways (i.e. they believe it to be more stable and less changeable) than withdrawal and (2) believe that friends hold a greater potential to create change in aggression and withdrawal than do other potential sources of influence, such as parents and teachers. Study 2 (N=25) replicates the findings of Study 1 and also demonstrates that by preschool age, children hold systematic ideas about the effectiveness of strategies that friends can use to change the behaviour of their peers. These ideas include the belief that prosocial strategies, such as showing peers how to make friends, are more effective than requests to stop engaging in undesirable behaviour. Study 2 also demonstrates that preschool-aged participants engaged in essentialist reasoning to a greater extent than did a comparison group of 20 7,8 year olds. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Quantification of blood intake of the head louse: Pediculus humanus capitis

INTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 5 2006
Rick Speare MB
Although head lice, Pediculus humanus capitis, are globally prevalent blood-sucking ectoparasites, the amount of blood imbibed by head lice has not been determined. This study investigated this parameter, as regular loss of a small quantity of blood may lead to an iron deficiency and anaemia. Adult female lice (66), adult males (46), and nymphs (152) were weighed before and after feeding in groups of 17,109 lice. The average amounts of blood imbibed at a single feed were: adult female louse (0.0001579 ml), adult male (0.0000657 ml) and nymph (0.0000387 ml). Assuming three feeds per day by an average infection of 30 lice (10 females, 10 males, and 10 nymphs), the average child with active pediculosis would loose 0.008 ml of blood per day. This amount of blood loss is of no clinical significance even in iron-deficient children. The most heavily infected child observed with 2657 lice could be expected to loose 0.7 ml/day or 20.8 ml/month, which may be of clinical importance in a child on an adequate diet, and would be significant in an iron-deficient child. However, if head lice feed more often than three times a day, a heavy infestation would have a greater potential to lead to iron deficiency. The frequency of feeding of head lice on the head of the human host needs to be determined. [source]

Simulation of an integrated PCM,wallboard system

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 3 2003
J.-S. Kim
Abstract Heat transfer barriers and other practical difficulties do currently hamper the development and application of (phase change materials) PCM,wallboard systems. In this study thermal performance of randomly mixed PCM and laminated PCM,wallboard systems have been numerically evaluated and results compared. The laminated system displayed up to 50% increment in heat flux enhancement and about 18% increase in heat transfer rates. Consequently, the laminated PCM,wallboard system has greater potential for heating and cooling application in buildings than the randomly mixed system. Experimental validation and investigation into manufacturing techniques are however needed to establish the commercial viability. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Workers' Remittances to India: An Examination of Transfer Cost and Efficiency

INTERNATIONAL MIGRATION, Issue 5 2010
Bhupal Singh
Regarding the time efficiency of remittance transfer channels to India, the evidence suggests that traditional banking instruments are relatively inefficient as compared to the new information technology-enabled products. Transfer arrangement of the Indian banks with overseas exchange houses has reduced the settlement cycle and the cost. Both the banks and money transfer operators (MTOs) are able to keep the transaction cycle low through the use of information technology-enabled formats. Given that the average cost curve of the banks is located to the right of the average cost curve of the MTOs, greater potential exists for the improvement in overall efficiency of the two entities, particularly through the sharing of messaging and the access and disbursement networks to reduce the overhead cost. The estimates of error correction model reveal that the transaction fee and payment infrastructure are significant determinants of remittance flows, underscoring the scope of policy measures in influencing remittance inflows. The estimates indicate that over the medium to long-term horizon, transaction cost emerges as the most dominant variable explaining the variation in remittances. The payments infrastructure also explains about 10 per cent variation in remittances over the medium-term. The impulse response analysis further reveals that the favourable shocks to transaction fees and the payments infrastructure cause steady improvement in remittance inflows over the medium-term horizon, thus underlining the importance of cost and efficiency in affecting the workers' remittances. [source]

Generalized marker regression and interval QTL mapping methods for binary traits in half-sib family designs

JOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 5 2001
H. N. Kadarmideen
A Generalized Marker Regression Mapping (GMR) approach was developed for mapping Quantitative Trait Loci (QTL) affecting binary polygenic traits in a single-family half-sib design. The GMR is based on threshold-liability model theory and regression of offspring phenotype on expected marker genotypes at flanking marker loci. Using simulation, statistical power and bias of QTL mapping for binary traits by GMR was compared with full QTL interval mapping based on a threshold model (GIM) and with a linear marker regression mapping method (LMR). Empirical significance threshold values, power and estimates of QTL location and effect were identical for GIM and GMR when QTL mapping was restricted to within the marker interval. These results show that the theory of the marker regression method for QTL mapping is also applicable to binary traits and possibly for traits with other non-normal distributions. The linear and threshold models based on marker regression (LMR and GMR) also resulted in similar estimates and power for large progeny group sizes, indicating that LMR can be used for binary data for balanced designs with large families, as this method is computationally simpler than GMR. GMR may have a greater potential than LMR for QTL mapping for binary traits in complex situations such as QTL mapping with complex pedigrees, random models and models with interactions. Generalisierte Marker Regression und Intervall QTL Kartierungsmethoden für binäre Merkmale in einem Halbgeschwisterdesign Es wurde ein Ansatz zur generalisierten Marker Regressions Kartierung (GMR) entwickelt, um quantitative Merkmalsloci (QTL) zu kartieren, die binäre polygenetische Merkmale in einem Einfamilien-Halbgeschwisterdesign beeinflussen. Das GMR basiert auf der Theorie eines Schwellenwertmodells und auf der Regression des Nachkommenphänotyps auf den erwarteten Markergenotyp der flankierenden Markerloci. Mittels Simulation wurde die statistische Power und Schiefe der QTL Kartierung für binäre Merkmale nach GMR verglichen mit vollständiger QTL Intervallkartierung, die auf einem Schwellenmodell (GIM) basiert, und mit einer Methode zur linearen Marker Regressions Kartierung (LMR). Empirische Signifikanzschwellenwerte, Power und Schätzer für die QTL Lokation und der Effekt waren für GIM und GMR identisch, so lange die QTL Kartierung innerhalb des Markerintervalls definiert war. Diese Ergebnisse zeigen, dass die Theorie der Marker Regressions-Methode zur QTL Kartierung auch für binäre Merkmale und möglicherweise auch für Merkmale, die keiner Normalverteilung folgen, geeignet ist. Die linearen und Schwellenmodelle, die auf Marker Regression (LMR und GMR) basieren, ergaben ebenfalls ähnliche Schätzer und Power bei großen Nachkommengruppen, was schlussfolgern lässt, dass LMR für binäre Daten in einem balancierten Design mit großen Familien genutzt werden kann. Schließlich ist diese Methode computertechnisch einfacher als GMR. GMR mag für die QTL Kartierung bei binären Merkmalen in komplexen Situationen ein größeres Potential haben als LMR. Ein Beispiel dafür ist die QTL Kartierung mit komplexen Pedigrees, zufälligen Modellen und Interaktionsmodellen. [source]

Free radical,scavenging activity and DNA damaging potential of auxins IAA and 2-methyl-IAA evaluated in human neutrophils by the alkaline comet assay

JOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 3 2010
Branka Salopek-Sondi
Auxins, of which indole-3-acetic acid (IAA) is the most widespread representative, are plant hormones. In addition to plants, IAA also naturally occurs in humans in micromolar concentrations. In the presence of peroxidase, indolic auxins are converted to cytotoxic oxidation products and have thus been proposed for use in gene-directed enzyme/prodrug tumor therapy. Since data on the genotoxicity of IAA and its derivatives are not consistent, here we investigate the early DNA damaging effects (2-h treatment) of the auxins, IAA, and 2-methyl-indole-3-acetic acid (2-Me-IAA) by the alkaline comet assay and compare them with their free radical,scavenging activity measured by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Human neutrophils are chosen as the test system since they possess inherent peroxidase activity. The results of the comet assay indicate an increase in DNA damage in a dose-dependent manner up to 1.00 mM of both auxins. Generally, IAA applied in the same concentration had greater potential to damage DNA in human neutrophils than did 2-Me-IAA. The genotoxicities of the two examined auxins are negatively correlated with their antioxidant activities, as measured by the DPPH assay; 2-Me-IAA showed a higher antioxidant capacity than did IAA. We assume that differences in the molecular structure of the tested auxins contributed to differences in their metabolism, in particular, with respect to interactions with peroxidases and other oxidative enzymes in neutrophils. However, the exact mechanisms have to be elucidated in future studies. © 2010 Wiley Periodicals, Inc. J Biochem Mol Toxicol 24:165,173, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20323 [source]

Molecular alterations resulting from frameshift mutations in peripheral myelin protein 22: Implications for neuropathy severity

JOURNAL OF NEUROSCIENCE RESEARCH, Issue 6 2005
J.S. Johnson
Abstract Alterations in peripheral myelin protein 22 (PMP22) expression are associated with a heterogeneous group of hereditary demyelinating peripheral neuropathies. Two mutations at glycine 94, a single guanine insertion or deletion in PMP22, result in different reading frameshifts and, consequently, an extended G94fsX222 or a truncated G94fsX110 protein, respectively. Both of these autosomal dominant mutations alter the second half of PMP22 and yet are linked to clinical phenotypes with distinct severities. The G94fsX222 is associated with hereditary neuropathy with liability to pressure palsies, whereas G94fsX110 causes severe neuropathy diagnosed as Dejerine-Sottas disease or Charcot-Marie-Tooth disease type IA. To investigate the subcellular changes associated with the G94 frameshift mutations, we expressed epitope-tagged forms in primary rat Schwann cells. Biochemical and immunolabeling studies indicate that, unlike the wild-type protein, which is targeted for the plasma membrane, frameshift PMP22s are retained in the cell, prior to reaching the medial Golgi compartment. Similar to Wt-PMP22, both frameshift mutants are targeted for proteasomal degradation and accumulate in detergent-insoluble, ubiquitin-containing aggregates upon inhibition of this pathway. The extended frameshift PMP22 shows the ability to form spontaneous aggregates in the absence of proteasome inhibition. On the other hand, Schwann cells expressing the truncated protein proliferate at a significantly higher rate than Schwann cells expressing the wild-type or the extended PMP22. In summary, these results suggest that a greater potential for PMP22 aggregation is associated with a less severe phenotype, whereas dysregulation of Schwann cell proliferation is linked to severe neuropathy. © 2005 Wiley-Liss, Inc. [source]

Feeding success of African wild dogs (Lycaon pictus) in the Serengeti: the effects of group size and kleptoparasitism

JOURNAL OF ZOOLOGY, Issue 2 2005
C. Carbone
Abstract Longer-term ecosystem level dynamics are often neglected in conservation studies involving single species. In this study, a retrospective analysis is presented on the feeding performance of African wild dogs Lycaon pictus in the Serengeti in relation to a competing species, the spotted hyena Crocuta crocuta, to test whether hyenas had an effect on feeding performance of wild dogs in this ecosystem. Our analysis is based on observations of over 700 wild dog kills recorded over a 20-year period (from 1964 to 1987) during which time there was a decline in wild dog numbers (ending with their local extinction in 1991) and a twofold increase in hyena density. Overall, the amount of time that dogs had access to the kill (access time) decreased with increasing numbers of hyenas attending kills, but access time increased with increasing hunting-group size of dogs and carcass mass. In addition, in the 1980s, dogs spent longer at kills than in the 1970s for a given set of conditions, including when hyenas were absent. Our analysis demonstrates a greater potential for group benefits than was found in a previous study (Carbone, Du Toit et al., 1997). Hunting-group sizes of between two and six dogs performed best when hyenas attended dog kills because the benefits of increased defence outweighed the costs of having to share the carcass with more dogs. Hunting-group sizes of wild dog and levels of hyena attendance at the kill broadly paralleled the population trends in these species, with hunting-group sizes of wild dog declining, followed by hyena attendance increasing. Despite the combined effects of increased hyena attendance and reduced hunting-group size, dogs in the 1980s typically spent longer feeding and consumed more of the carcass including the poorest sections. This suggests that dogs in the 1980s may have been under greater energetic stress. [source]

Business portfolio restructuring, prior diversification posture and investor reactions

MANAGERIAL AND DECISION ECONOMICS, Issue 8 2003
Robin T. Byerly
This study examined firm performance in market reaction to two types of business portfolio restructuring announcements: refocusing and repositioning. We predicted that market performance effects for these two types of strategic restructurers would be moderated by prior diversification posture. The theory behind these expectations was built on a general premise that restructuring strategy would be more favorably viewed by the market as performance enhancing when it offered greater potential for organizational transformation. Results showed strong support for our conclusion that prior diversification posture poses a significant contingency factor in restructuring firms' strategic choices. Further, the market tended to respond more favorably with this sample to repositioning restructuring choices. Copyright © 2003 John Wiley & Sons, Ltd. [source]

A Retrospective Study of the Incidence of Neurological Injury after Axillary Brachial Plexus Block

PAIN PRACTICE, Issue 2 2006
B. Ben-David MD
Abstract Background: It has been suggested that performing a nerve block under general anesthesia, as customary in pediatric population, may predispose to nerve injury. However, few clinical data exist to either support or refute this assertion. Methods: We retrospectively reviewed data on all patients who received an axillary block for upper extremity surgery in our institution during an eight-year period. The blocks were performed under sedation or general anesthesia, without using a nerve stimulator. Perioperative records from the Hand Surgery Unit Clinic were reviewed for postoperative complaints and complications. Results: In the eight-year period of the review, 336 patients had axillary block. In total, 230 received the block with sedation and 106 during general anesthesia. All the sedated patients were older than 14 years (mean age 45.2), while of the general anesthesia patients 48 were older than 14 years (mean age 13.9 years). There were six cases of postoperative nerve injury in sedated patients (2.6%) vs. eight cases (7.5%) in the general anesthesia patients. Most patients recovered fully within several weeks. One patient had permanent nerve injury. Conclusions: Definitive conclusions cannot be drawn because of disparities in patient group demographics (majority of pediatric patients were in the general anesthesia group) and the retrospective nature of this study. Nevertheless, the findings suggest that the conduct of axillary block under general anesthesia in pediatric patients holds a greater potential for nerve injury than when the block is performed under sedation in adults. [source]

The response of photosynthesis and stomatal conductance to rising [CO2]: mechanisms and environmental interactions

PLANT CELL & ENVIRONMENT, Issue 3 2007
ELIZABETH A. AINSWORTH
ABSTRACT This review summarizes current understanding of the mechanisms that underlie the response of photosynthesis and stomatal conductance to elevated carbon dioxide concentration ([CO2]), and examines how downstream processes and environmental constraints modulate these two fundamental responses. The results from free-air CO2 enrichment (FACE) experiments were summarized via meta-analysis to quantify the mean responses of stomatal and photosynthetic parameters to elevated [CO2]. Elevation of [CO2] in FACE experiments reduced stomatal conductance by 22%, yet, this reduction was not associated with a similar change in stomatal density. Elevated [CO2] stimulated light-saturated photosynthesis (Asat) in C3 plants grown in FACE by an average of 31%. However, the magnitude of the increase in Asat varied with functional group and environment. Functional groups with ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco)-limited photosynthesis at elevated [CO2] had greater potential for increases in Asat than those where photosynthesis became ribulose-1,5-bisphosphate (RubP)-limited at elevated [CO2]. Both nitrogen supply and sink capacity modulated the response of photosynthesis to elevated [CO2] through their impact on the acclimation of carboxylation capacity. Increased understanding of the molecular and biochemical mechanisms by which plants respond to elevated [CO2], and the feedback of environmental factors upon them, will improve our ability to predict ecosystem responses to rising [CO2] and increase our potential to adapt crops and managed ecosystems to future atmospheric [CO2]. [source]

The Not-so-Dark Ages: Ecology for human growth in medieval and early Twentieth Century Portugal as inferred from skeletal growth profiles

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2009
Hugo F.V. Cardoso
Abstract This study attempts to address the issue of relative living standards in Portuguese medieval and early 20th century periods. Since the growth of children provides a good measure of environmental quality for the overall population, the skeletal growth profiles of medieval Leiria and early 20th century Lisbon were compared. Results show that growth in femur length of medieval children did not differ significantly from that of early 20th century children, but after puberty medieval adolescents seem to have recovered, as they have significantly longer femora as adults. This is suggestive of greater potential for catch-up growth in medieval adolescents. We suggest that this results from distinct child labor practices, which impact differentially on the growth of Leiria and Lisbon adolescents. Work for medieval children and adolescents were related to family activities, and care and attention were provided by family members. Conversely, in early 20th century Lisbon children were more often sent to factories at around 12 years of age as an extra source of family income, where they were exploited for their labor. Since medieval and early 20th century children were stunted at an early age, greater potential for catch-up growth in medieval adolescents results from exhausting work being added to modern adolescent's burdens of disease and poor diet, when they entered the labor market. Although early 20th century Lisbon did not differ in overall unfavorable living conditions from medieval Leiria, after puberty different child labor practices may have placed modern adolescents at greater risk of undernutrition and poor growth. Am J Phys Anthropol 2009. © 2008 Wiley-Liss, Inc. [source]

Effect of exercise training on endothelium-derived nitric oxide function in humans

THE JOURNAL OF PHYSIOLOGY, Issue 1 2004
Daniel J. Green
Vascular endothelial function is essential for maintenance of health of the vessel wall and for vasomotor control in both conduit and resistance vessels. These functions are due to the production of numerous autacoids, of which nitric oxide (NO) has been the most widely studied. Exercise training has been shown, in many animal and human studies, to augment endothelial, NO-dependent vasodilatation in both large and small vessels. The extent of the improvement in humans depends upon the muscle mass subjected to training; with forearm exercise, changes are restricted to the forearm vessels while lower body training can induce generalized benefit. Increased NO bioactivity with exercise training has been readily and consistently demonstrated in subjects with cardiovascular disease and risk factors, in whom antecedent endothelial dysfunction exists. These conditions may all be associated with increased oxygen free radicals which impact on NO synthase activity and with which NO reacts; repeated exercise and shear stress stimulation of NO bioactivity redresses this radical imbalance, hence leading to greater potential for autacoid bioavailability. Recent human studies also indicate that exercise training may improve endothelial function by up-regulating eNOS protein expression and phosphorylation. While improvement in NO vasodilator function has been less frequently found in healthy subjects, a higher level of training may lead to improvement. Regarding time course, studies indicate that short-term training increases NO bioactivity, which acts to homeostatically regulate the shear stress associated with exercise. Whilst the increase in NO bioactivity dissipates within weeks of training cessation, studies also indicate that if exercise is maintained, the short-term functional adaptation is succeeded by NO-dependent structural changes, leading to arterial remodelling and structural normalization of shear. Given the strong prognostic links between vascular structure, function and cardiovascular events, the implications of these findings are obvious, yet many unanswered questions remain, not only concerning the mechanisms responsible for NO bioactivity, the nature of the cellular effect and relevance of other autacoids, but also such practical questions as the optimal intensity, modality and volume of exercise training required in different populations. [source]

Litter decomposition in a sandy Monte desert of western Argentina: Influences of vegetation patches and summer rainfall

AUSTRAL ECOLOGY, Issue 7 2006
EDUARDO PUCHETA
Abstract: We tested the hypothesis that shrub canopies interact with monthly rain pulses to control litter decomposition in a sandy Monte desert, in Argentina. We assessed (i) the potential for litter decomposition of soils beneath the canopies of two dominant shrub species (Larrea divaricata and Bulnesia retama, Zygophyllaceae R. Br.) and from bare-ground microsites or ,openings'; (ii) litter decomposition at different spatial patches over the summer rainy season; and (iii) the interaction between vegetation patches and monthly rain pulses on short-term litter decomposition, or decomposition pulses. In a greenhouse experiment, we found buried litter decomposition to be higher in soils from under the canopies of a dominant shrub species compared with soils from openings and sterilized controls. This, and higher nutrient concentration under shrub soils, suggest undercanopy soils may support a microbial community capable of decomposing litter at higher rates than soils in bare openings. However, ,eld trials showed that shrub patches did not affect leaf litter decomposition over the rainy season, at least for short periods. We found an interaction between shrub patches and incubation time at the end of the ,eld experiment, with higher litter decomposition rates under B. retama canopies. In a monthly ,eld experiment, we found monthly rain pulses signi,cantly explained decomposition pulses, irrespective of patch type. Our ,ndings support the hypothesis that shrub soils have a greater potential for litter decomposition, but this is not directly translated to the ,eld possibly due to interactions with abiotic factors. Rain pulses create conditions for decomposition pulses to occur at shorter time scales, whereas rainfall may interact with a dominant shrub undercanopy to control litter mass loss over longer time scales. [source]

Scaling-up from leaf to canopy-aggregate properties in sclerophyll shrub species

AUSTRAL ECOLOGY, Issue 3 2006
CASSIA READ
Abstract: Plant species vary widely in their average leaf lifespan (LL) and specific leaf area (SLA, leaf area per dry mass). The negative LL,SLA relationship commonly seen among species represents an important evolutionary trade-off, with higher SLA indicating greater potential for fast growth (higher rate of return on a given investment), but longer LL indicating a longer duration of the revenue stream from that investment. We investigated how these leaf-economic traits related to aggregate properties of the plant crown. Across 14 Australian sclerophyll shrub species, those with long LL accumulated more leaf mass and leaf area per unit ground area. Light attenuation through their canopies was more severe. Leaf accumulation and light attenuation were more weakly related to SLA than to LL. The greater accumulation of foliage in species with longer LL and lower SLA may counterbalance their generally lower photosynthetic rates and light-capture areas per gram of leaf. [source]

An in vitro study of the antimicrobial activity of some endodontic medicaments against Enteroccus faecalis biofilms

AUSTRALIAN DENTAL JOURNAL, Issue 2 2010
B Athanassiadis
Abstract Background:, The in vitro antimicrobial activity of a series of endodontic medicaments and their bases against biofilms of Enterococcus faecalis was investigated. Methods:, The medicaments tested were Pulpdent paste, Ledermix paste, a 50:50 Ledermix and Pulpdent mixture, and a replica of Ledermix paste. Bases included methyl cellulose with water, polyethylene glycol (PEG), and PEG with zinc oxide, calcium chloride and the other components (inactives) that make up the Ledermix paste base. Biofilms grown on cellulose nitrate membrane filters were exposed to the medicaments for up to 5 days. The number of surviving colony forming units (CFU) was determined at days 1, 3 and 5. The results were expressed as a bacterial survival index (BSI) when compared to the unexposed control. Results:, Pulpdent produced the greatest reduction of BSI, followed by the 50:50 mixture of Pulpdent and Ledermix pastes. Ledermix paste, its replica and the individual bases showed no significant reductions in the BSI for E. faecalis. Conclusions:, Within the limitations of this laboratory study, calcium hydroxide containing preparations had greater potential for reducing the survival of E. faecalis in a biofilm environment. [source]

Accounting for Multiplicities in Assessing Drug Safety: A Three-Level Hierarchical Mixture Model

BIOMETRICS, Issue 2 2004
Scott M. Berry
Summary. Multiple comparisons and other multiplicities are among the most difficult of problems that face statisticians, frequentists, and Bayesians alike. An example is the analysis of the many types of adverse events (AEs) that are recorded in drug clinical trials. We propose a three-level hierarchical mixed model. The most basic level is type of AE. The second level is body system, each of which contains a number of types of possibly related AEs. The highest level is the collection of all body systems. Our analysis allows for borrowing across body systems, but there is greater potential,depending on the actual data,for borrowing within each body system. The probability that a drug has caused a type of AE is greater if its rate is elevated for several types of AEs within the same body system than if the AEs with elevated rates were in different body systems. We give examples to illustrate our method and we describe its application to other types of problems. [source]

Targeted therapy in inflammatory breast cancer,

CANCER, Issue S11 2010
Hideko Yamauchi MD
Abstract Despite the introduction of multimodality treatment approaches, the prognosis of inflammatory breast cancer (IBC) is poor. Recent developments in molecular targeted therapy may be effective against IBC. The authors report the results of a literature review. Trastuzumab and lapatinib, which target human epidermal growth factor receptor 2 (HER-2), have demonstrated benefit in clinical trials for HER-2,positive breast cancers. WNT1-inducible signaling pathway protein 3, Ras homolog gene family member C guanosine triphosphatase, epidermal growth factor receptor (EGFR), and p27kip1 also have been studied as potential targets in IBC. Molecular targets in vasculolymphatic processes (angiogenesis, lymphangiogenesis, and vasculogenesis) have demonstrated greater potential in IBC than in non-IBC. Although loss of E-cadherin is a hallmark of epithelial-to-mesenchymal transition and may correlate with the promotion of metastasis, paradoxically, E-cadherin is overexpressed in IBC through an unknown mechanism. On the basis of dissecting the molecular mechanism of the aggressiveness of IBC, the authors currently are investigating whether EGFR may aid in developing innovative targeted therapies. Cancer 2010;116(11 suppl):2758,9. © 2010 American Cancer Society. [source]