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Long Period (long + period)
Selected AbstractsLong periods of boredom interspersed by brief moments of terror?EARTH SURFACE PROCESSES AND LANDFORMS, Issue 1 2008Stuart Lane No abstract is available for this article. [source] Longitudinal patterns of new Benzodiazepine use in the elderly,PHARMACOEPIDEMIOLOGY AND DRUG SAFETY, Issue 10 2004Gillian Bartlett PhD Abstract Purpose To characterize longitudinal patterns of Benzodiazepine use in the elderly. Methods Prospective cohort of 78,367 community-dwelling Quebec residents aged 66 years or more who were new Benzodiazepine users, was followed for 5 years, 1989,1994. Data acquired from four population-based, provincial administrative databases were used to create time-dependent measures of change in dosage, switching or adding Benzodiazepines for 11 drugs listed in the provincial formulary. Subject-specific Spearman's rank correlation coefficients between dose and time were used to measure the tendency of increasing dose with consecutive periods of use. Multiple logistic regression and generalized estimating equations (GEE) models evaluated subject characteristics associated with increasing dose. Results The mean duration of uninterrupted Benzodiazepine use was 75.5 days. The mean daily dose was about half the recommended adult daily dose but 8.6% of subjects exceeded the recommended adult dose. Some of them (28.8%) switched medications at least once and 8.2% filled two or more prescriptions concurrently. For women, older age at date of first prescription was associated with increasing dose over time (odds ratio (OR) for 10 year age increase,=,1.23, p,<,0.001). Conclusion Long periods of Benzodiazepine use are frequent among Quebec elderly. The evidence of increasing dose, particularly for older women, and long-duration of use has important implications for clinicians. Copyright © 2003 John Wiley & Sons, Ltd. [source] Patterns of precursor behaviors in the life span of a U.S. environmental terrorist groupCRIMINOLOGY AND PUBLIC POLICY, Issue 3 2009Brent L. Smith Research Summary This article discusses the paucity of data available for assessing the "life span" of a terrorist group. It introduces a new methodology that allows researchers to examine when terrorist groups perform their preincident activities. The findings suggest that differences exist in the temporal patterns of terrorist groups: environmental terrorist groups engage in a relatively short planning cycle compared with right-wing and international terrorists. The article concludes by examining a case study on "the Family," which is a unique environmental terrorist group that conducted activities over a relatively long period of time. This group provides an interesting contrast to other environmental terrorists. Despite significant organizational differences, their patterns of preparatory conduct were highly similar. Policy Implications The findings suggest that (1) temporal and spatial data about preincident terrorist activity can be collected from unclassified and open sources and (2) law-enforcement agencies that are investigating environmental groups have relatively little time to observe and infiltrate their individual cells (compared with right-wing and international terrorists). Finally, the data suggest that environmental terrorists,at least so far,have engaged in attacks that are less deadly than the comparison groups. [source] Follow-Up of 1 mg Finasteride Treatment of Male Pattern Baldness,Difference between Clinical Trials and Private Office Follow-Up: Influences on Prescribing Habits EvaluatedDERMATOLOGIC SURGERY, Issue 5 2004Marvin J. Rapaport MD Background. Finasteride (Propecia) was approved by the FDA in 1998 for treating men with androgenetic alopecia. The published clinical trials demonstrated statistical differences between drug and placebo. Rarely do new drugs undergo further non-drug-company-sponsored studies of efficacy. Concerns about clinical studies and marketing of drugs prompted this evaluation of a large group of patients taking this medication. Objective. Finasteride usage offered an opportunity not only to understand the acceptance of a cosmetically oriented medication, but also to evaluate subjective comments and compliance after a long period of time. Methods. A total of 1261 patients were monitored with phone calls every 3 months after finasteride was initially prescribed. After 12 months, a detailed questionnaire was sent to all patients with an additional letter and two telephone calls if no response was received. Statistical analysis of the patients' data was made. Results. Thirty-two percent or 414 men continued to take finasteride daily for 1 to 3 years. Twenty-four percent or 297 men discontinued the drug between 3 and 15 months owing to poor results. The remaining 44% or 549 men were lost to follow-up despite numerous attempts to contact them. Conclusion. A total of 414 men continued to take the medication, but only 211 returned detailed questionnaires. A small percentage of this group felt that they grew hair. The remaining patients noted poor results. [source] Flood Disasters and Agricultural Wages in BangladeshDEVELOPMENT AND CHANGE, Issue 4 2007Lopamudra Banerjee ABSTRACT This article examines the effects of abnormal floods on agricultural wages in Bangladesh. Drawing upon the district-wise monthly real wage data for the period 1979,2000, it shows that wages decline sharply in the regions that are severely inundated for a long period of time. Wages may remain depressed in these regions even in the post-flood months. However, wages increase in the flood months in the regions that remain submerged for short durations. The article examines the district-wise crop yield data to explain these results in terms of the impact of flood on agricultural productivity, and therefore the demand for labour. [source] Case of eosinophilic granulomatous enterocolitis caused by Strongyloides stercoralis infection with marked hypoalbuminemia and ascitesDIGESTIVE ENDOSCOPY, Issue 3 2004Nuthapong Ukarapol We report a 10-year-old boy presenting with generalized pitting edema, ascites, abdominal pain, and chronic mucous diarrhea for 4 weeks. He had underlying diseases of hemoglobin E and juvenile rheumatoid arthritis and had been treated with immunosuppressive agents for a long period of time, including prednisolone and methotrexate. After extensive investigations, Strongyloides stercoralis infection, leading to protein-losing enteropathy and eosinophilic granulomatous enterocolitis, was diagnosed. In the present report, we demonstrate early colonoscopic findings, revealing patchy erythema and small raised mucosal nodules with erosions at the cecum. Histopathological study showed open ulceration with cryptitis, intense infiltration of eosinophils and histiocytes with granuloma formation, in which Strongyloides stercoralis larvae were noted. [source] Multi-year tracking of sediment sources in a small agricultural watershed using rare earth elementsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 14 2006A. Kimoto Abstract Rare earth elements (REEs) have been successfully used as a sediment tracer, but the REE technique has never been used for studying sediment sources for a multi-year period. A nearly four-year field experiment was conducted on a small agricultural watershed near Coshocton, OH, USA, to assess the applicability of the REE technique for a multi-year period and to evaluate the relative contributions of sediment sources in the watershed. Tracer depletion and tracer enrichment ratio (ratio of the tracer concentrations in sediment to the concentrations in the soil in the areas of application) were evaluated to examine the applicability and accuracy of the technique. A minimum of 91 per cent of the mass of the applied elements was still available on any individual morphological element at the end of the experimental period. The tracer enrichment ratio varied from 0·4 to 2·3, and it was not significantly related to time. The relative contributions of six morphological elements within the watershed were evaluated as proportions to total sediment yield. The relative contribution of the lower channel was significantly increased as a function of the amount of sediment yield, while that of the lower backslope was significantly decreased. The relative contribution of the lower channel significantly decreased as a function of cumulative sediment yield, while the contributions of the shoulder and the upper backslope significantly increased. Our results showed that the REE technique can be used to track sediment sources for a relatively long period with two limitations or potential sources of error associated with a selective depletion of tracers and a contamination of downslope areas with tagged sediments from upslope areas. Copyright © 2006 John Wiley & Sons, Ltd. [source] Effects of environmental perturbations on abundance of subarctic plants after three, seven and ten years of treatmentsECOGRAPHY, Issue 1 2001Enrico Graglia Analyses of changes in vegetation were carried out after three, seven and ten years of fertilizer addition, warming and light attenuation in two subarctic, alpine dwarf shrub heaths. One site was just above the tree line, at ca 450 m a.s.l., and the other at a much colder fell-field at ca 1150 m altitude. The aim was to investigate how the treatments affected the abundance of different species and growth forms over time, including examinations of transient changes. Grasses, which increased in abundance by fertilizer addition, and cryptogams, which, by contrast, decreased by fertilizer addition and warming, were the most sensitive functional groups to the treatments at both sites. Nutrient addition exerted a stronger and more consistent effect than both shading and warming. Warming at the fell-field had slightly greater effect than at the warmer tree line with an increase in deciduous shrubs. The decreased abundance of mosses and lichens to fertilizer addition and/or warming was most likely an indirect treatment effect, caused by competition through increased abundance and overgrowth of grasses. Such changes in species composition are likely to alter decomposition rates and the water and energy exchange at the soil surface. We observed few, if any, transient effects of declining responses during the 10 yr of treatments. Instead, there were many cumulative effects of the treatments for all functional groups and many interactions between time and treatment, suggesting that once a change in community composition is triggered, it will continue with unchanged or accelerated rate for a long period of time. [source] The production and consumption of bar iron in early modern England and WalesECONOMIC HISTORY REVIEW, Issue 1 2005PETER KING Errata. The Economic History Review 59: 1, 64 The production and consumption of bar iron in early modern England and Wales. An estimate made of the bar iron production in England shows two periods when production grew rapidly, 1540-1620 and 1785-1810. Both of these were related to the adoption of new technology-the finery forge in the first case, and potting and stamping and then puddling in the second. Imports of iron from Spain declined sharply after 1540, but those from Sweden became significant from the mid-seventeenth century, and those from Russia after 1730. Consumption grew rapidly in the late sixteenth century, and again during the eighteenth. Hence, the industrial revolution was the culmination of a long period of growth. [source] Selection of hibernation sites by Anthonomus pomorum: preferences and ecological consequencesENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2000St. Toepfer Abstract The apple blossom weevil, Anthonomus pomorum (L.) (Coleoptera: Curculionidae), has a long period of aestivo-hibernation in the adult stage lasting from summer to early spring of the following year. Potential hibernation sites within an apple orchard consist of high-stem rough-bark trees or dwarf smooth-bark trees. Field release-recapture experiments in 2 consecutive years showed that 64 and 47% of the weevils remained in the vicinity of the release sites in an area of high-stem trees and dwarf trees, respectively. The dispersing weevils moved over an average distance of 5.5 m in the dwarf tree area, as compared to 3.8 m in the high-stem tree area. The prevalent direction of dispersal was along tree rows in both areas. Some weevils displayed, after release in mid-July, a directional dispersal to the adjacent forests. Others, released in the dwarf tree area, dispersed towards the area of high-stem rough-bark apple trees. Experiments simulating various hibernation sites demonstrated that the litter of dry leaves was the most preferred overwintering shelter, yielding a relatively high survival rate. Branches with rough bark ranked second, while branches with smooth bark, grass and pure soil were not favourable for overwintering. Flight tendency in newly emerged weevils of summer generation was significantly higher in June/July than in August/September. This corresponds to the dispersal behaviour in the field. The timing of spring colonisation of apple trees was similar for weevils overwintering within the orchard and for those from outside. These results suggest that modern, dwarf apple orchards offer unfavourable conditions for overwintering, but that the relatively small proportion of weevils which manage to reach the adjacent forests find optimal hibernation sites there. [source] Clinical and radiological features of symptomatic central nervous system tuberculomasEUROPEAN JOURNAL OF NEUROLOGY, Issue 10 2005A. Unal Tuberculomas may present with meningitis, may lead to meningitis, or may develop during the treatment of TBM. In this study, we report a series of 22 adult cases of symptomatic central nervous system tuberculomas, in eight of them tuberculomas were coexisting with TBM on admission and in 14 of them symptomatic tuberculomas developed during anti-tuberculosis therapy. We also aimed to compare the clinical, laboratory and outcome data of the 14 TBM patients that developed symptomatic tuberculomas, with the data of 41 TBM that did not, under the same treatment regimen. Most of the patients developed symptomatic tuberculomas in the first 6 weeks of treatment. Five patients developed late tuberculomas. The characteristics of tuberculomas and the role of corticosteroids in TBM patients are discussed. In conclusion, although steroids may diminish neurologic symptoms and improve outcome, tuberculomas may appear during the course of anti-tuberculosis and steroid treatment. Because of the possibility of late development of tuberculomas after initial successful treatment, all TBM patients need to be followed-up carefully for a long period. [source] Intrinsic and spontaneous neurogenesis in the postnatal slice culture of rat hippocampusEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2004Maki Kamada Abstract Organotypic slice culture preserves the morphological and physiological features of the hippocampus of live animals for a certain time. The hippocampus is one of exceptional regions where neurons are generated intrinsically and spontaneously throughout postnatal life. We investigated the possibility that neurons are generated continuously at the dentate granule cell layer (GCL) in slice culture of the rat hippocampus. Using 5-bromodeoxyuridine (BrdU) labelling and retrovirus vector transduction methods, the phenotypes of the newly generated cells were identified immunohistochemically. At 4 weeks after BrdU exposure, BrdU-labelled cells were found in the GCL and were immunoreactive with a neuronal marker, anti-NeuN. There were fibrils immunoreactive with anti-glial fibrillary acidic protein (GFAP), an astrocyte marker, in the layer covering the GCL and occasionally encapsulated BrdU-labelled nuclei. When the newly divided cells were marked with the enhanced green fluorescent protein (EGFP) using a retrovirus vector, these cells had proliferative abilities throughout the following 4-week cultivation period. Four weeks after the inoculation, the EGFP-expressing cells consisted of various phenotypes of both early and late stages of differentiation; some were NeuN-positive cells with appearances of neurons in the GCL and some were immunoreactive with anti-Tuj1, a marker of immature neurons. Some EGFP-expressing cells were immunoreactive with anti-GFAP or anti-nestin, a marker of neural progenitors. The present study suggests that slice cultures intrinsically retain spontaneous neurogenic abilities for their cultivation period. The combination of slice culture and retrovirus transduction methods enable the newly divided cells to be followed up for a long period. [source] Novel modelling of residual operating time of transformer oilEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 4 2003M. A. A. Wahab This paper presents techniques developed to accurately model the characteristics of transformer oil for the purpose of predicting the effect of aging on these characteristics. Aging causes some of the transformer oil characteristics to violate the internationally specified limits. The purpose of this simulation is to develop alternative techniques to predict the operating time after which these characteristics would violate the limits. The results obtained from monitoring of twenty in-service power transformers for long period of operating time up to ten years have been implemented in developing the proposed models. The physical, chemical and electrical characteristics have been determined periodically by internationally specified testing methods. The patterns of violation sequence of the standard limits, against operating time, by different transformer oil characteristics have been revealed and the most common pattern has been determined. The definition of residual operating time (trot) of the different transformer oil characteristics has been introduced. The choice of transformer oil breakdown voltage trot to represent that of the transformer oil characteristics has been justified. Modelling of trot as a function of transformer oil breakdown voltage, total acidity and water content by multiple-linear regression has been proposed and verified. Also, polynomial regression model of trot as a function only of transformer oil breakdown voltage has been given. The accuracy and applicability of these models and the different modelling techniques have been discussed and proved. [source] Photoaging and oxidative stressEXPERIMENTAL DERMATOLOGY, Issue 2003Chikako Nishigori Abstract Photoaging is significantly different from chronological aging in both clinical and histological appearance. It has been suggested that oxidative stress, generated by ultraviolet radiation (UVR), leads to photoaging over a long period. The presence of 8-OHdG, and oxidatively modified proteins such as 4-hydroxy-2-nonenal-modified protein, 3- l -nitro-tyrosine and N,,(carboxymethyl)lysine in UV-exposed skin specimens, supports this theory. The pathophysiology of photoaging of the skin caused by chronic inflammation after UVR is reviewed and discussed, with a focus on oxidative stress. [source] Fishery-induced demographic changes in the timing of spawning: consequences for reproductive success,FISH AND FISHERIES, Issue 3 2009Peter J. Wright Abstract Demography can have a significant effect on reproductive timing and the magnitude of such an effect can be comparable to environmentally induced variability. This effect arises because the individuals of many fish species spawn progressively earlier within a season and may produce more egg batches over a longer period as they get older, thus extending their lifetime spawning duration. Inter-annual variation in spawning time is a critical factor in reproductive success because it affects the early environmental conditions experienced by progeny and the period they have to complete phases of development. By reducing the average lifetime spawning duration within a fish stock, fishing pressure could be increasing the variability in reproductive success and reducing long-term stock reproductive potential. Empirical estimates of selection on birth date, from experiments and using otolith microstructure, demonstrate that there is considerable variation in selection on birth date both within a spawning season and between years. The few multi-year studies that have linked egg production with the survival of progeny to the juvenile stage further highlight the uncertainty that adults face in timing their spawning to optimize offspring survival. The production of many small batches of eggs over a long period of time within a season and over a lifetime is therefore likely to decrease variance and increase mean progeny survival. Quantifying this effect of demography on variability in survival requires a focus on lifetime reproductive success rather than year specific relationships between recruitment and stock reproductive potential. Modelling approaches are suggested that can better quantify the likely impact of changing spawning times on year-class strength and lifetime reproductive potential. The evidence presented strengthens the need to avoid fishing severely age truncated fish stocks. [source] Effects of floods versus low flows on invertebrates in a New Zealand gravel-bed riverFRESHWATER BIOLOGY, Issue 12 2006ALASTAIR M. SUREN Summary 1. Floods and low flows are hydrological events that influence river ecosystems, but few studies have compared their relative importance in structuring invertebrate communities. Invertebrates were sampled in riffles and runs at eight sites along 40 km of a New Zealand gravel-bed river every 1,3 months over 2.5 years, during which time a number of large flood and low flow events occurred. Flows were high in winter and spring, and low in summer and autumn. Four flow-related variables were calculated from hydrological data: flow on the day of sampling (Qsample), maximum and minimum flow between successive samples (Qmax and Qmin, respectively), and the number of days since the last bed-moving flood (Ndays). 2. The invertebrate community was summarised by relative densities of the 19 most abundant taxa and four biotic metrics [total abundance, taxon richness, the number of Ephemeroptera, Plecoptera and Trichoptera taxa (i.e. EPT richness), and per cent EPT]. Invertebrate density fluctuated greatly, and was high in summer and autumn, and low during winter and spring. Stepwise multiple regression (SMR) analysis was used to investigate relationships between the invertebrate community and season, flow, habitat and water temperature. 3. Seasonal variables were included in almost 50% of the SMR models, while flow-related variables were included in >75% of models. Densities of many taxa were negatively correlated to Qmin and Qmax, and positively correlated to Ndays, suggesting that while high flows reduced invertebrate densities, densities recovered with increasing time following a flood. Although season and flow were confounded in this study, many of the taxa analysed display little seasonal variation in abundance, suggesting that flow-related variables were more important in structuring communities than seasonal changes in density associated with life-cycles. 4. Five discrete flood and low flow events were identified and changes to invertebrate communities before and after these events examined. Invertebrate densities decreased more commonly after floods than after low flows, and there was a significant positive relationship between the number of taxa showing reductions in density and flood magnitude. Densities of most invertebrates either remained unchanged, or increased after low flow events, except for four taxa whose densities declined after a very long period (up to 9 months) of low flow. This decline was attributed to autogenic sloughing of thick periphyton communities and subsequent loss of habitat for these taxa. 5. Invertebrate communities changed more after floods and the degree of change was proportional to flood magnitude. Community similarity increased with increasing time since the last disturbance, suggesting that the longer stable flows lasted, the less the community changed. These results suggest that invertebrate communities in the Waipara River were controlled by both floods and low flows, but that the relative effects of floods were greater than even extended periods of extreme low flow. 6. Hydraulic conditions in riffles and runs were measured throughout the study. Riffles had consistently faster velocities, but were shallower and narrower than runs at all measured flows. Invertebrate density in riffles was expressed as a percentage of total density and regressed against the flow-related variables to see whether invertebrate locations changed according to flow. Significant negative relationships were observed between the per cent density of common taxa in riffles and Qsample, Qmax and Qmin. This result suggests either that these animals actively drifted into areas of faster velocity during low flows, or that their densities within riffles increased as the width of these habitats declined. [source] Effects of bears on rockshelter sediments at Tanay Sur-les-Creux, southwestern SwitzerlandGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 4 2004Luc Braillard Sur-les-Creux rockshelter is located in the Prealps of southwestern Switzerland. The sequence of deposits in the rockshelter is 80 cm thick and consists of weathered gravels in a phosphate-rich matrix. A few Middle Palaeolithic artifacts and the bones of cave bear (Ursus spelaeus) were recorded in the fill. We present the results of sedimentological, geochemical, and micromorphological analyses of the rockshelter sediment. All analyses suggest an endokarstic origin of the sediments. The alteration cortices of the gravels imply in situ weathering over a long period. The phosphates are essentially biogenic and have an apatitelike nature. Phosphatization and intense mixing of the sediment are attributed to cave bear (digging of lairs, input of excrements, and carcasses). Only rare carnivore coprolites (lynx) were preserved in the cave deposits. © 2004 Wiley Periodicals, Inc. [source] HYDROLOGY AND GEOMORPHIC EFFECTS OF A HIGH-MAGNITUDE FLOOD IN AN ALPINE RIVERGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 1 2007DAVID MORCHE ABSTRACT. The catchment of the River Partnach, a torrent situated in a glacial valley in the Northern Calcareous Alps of Bavaria/Germany, was affected by a high-magnitude flood on 22/23 August 2005 with a peak discharge of more than 16 m3s -1 at the spring and about 50 m3s -1 at the catchment outlet. This flood was caused by a long period of intense rainfall with a maximum intensity of 230 mm per day. During this event, a landslide dam, which previously held a small lake, failed. The flood wave originating from the dam breach transported a large volume of sediment (more than 50 000 m3) derived from bank erosion and the massive undercutting of a talus cone. This caused a fundamental transformation of the downstream channel system including the redistribution of large woody debris and channel switching. Using terrestrial survey and aerial photography, erosional and depositional consequences of the event were mapped, pre- and post-event surfaces were compared and the sediment budget of the event calculated for ten consecutive channel reaches downstream of the former lake. According to the calculations more than 100 000 tonnes of sediment were eroded, 75% of which was redeposited within the channel and the proximal floodplain. A previous large flood which occurred a few weeks prior to the August 2005 event had a significant effect on controlling the impact of this event. [source] Climatology at Urban Long-Term Ecological Research Sites: Baltimore Ecosystem Study and Central Arizona,PhoenixGEOGRAPHY COMPASS (ELECTRONIC), Issue 1 2009Anthony J. Brazel The Baltimore Ecosystem Study (BES) and Central Arizona,Phoenix (CAP) Long-Term Ecological Research (LTER) programs, established in 1997, are part of an international National Science Foundation long-term ecology monitoring and research network. The study sites are excellent laboratories to integrate ideas on climate of urban areas and how climate change and local variability of climate relate to social, political, economic, and ecological processes over a long time period. A large variety of research data are available online from individual LTER Web sites and a combined database called CLIMDB/HYDRODB is available for climate and ecology researchers and others, to investigate climate and hydrology in LTER study regions including those of BES and CAP. The basic program, climate aspects of these two areas, selected past research, and current ongoing work is briefly reviewed. A large benefit of this National Science Foundation program is the maintenance of support over a very long period of time. With the advent of a National Ecological Observatory Network, continuing collection of climate and environmental information over the coming decades at the local and regional scales, and maintenance of protocols of measurement, it is hoped that a more meaningfully integrated urban climatology with urban ecology will emerge. This will better prepare scientists to gage the impending rapid global warming expected not only of natural environments, but also of burgeoning urban places around the world. [source] Artificial neural network inversion of magnetotelluric data in terms of three-dimensional earth macroparametersGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2000Vjacheslav Spichak The possibility of solving the three-dimensional (3-D) inverse problem of geoelectrics using the artificial neural network (ANN) approach is investigated. The properties of a supervised ANN based on the back-propagation scheme with three layers of neurons are studied, and the ANN architecture is adjusted. A model class consisting of a dipping dyke in the basement of a two-layer earth with the dyke in contact with the overburden is used for numerical experiments. Six macroparameters of the 3-D model, namely the thickness of the top layer, which coincides with the depth of the dyke (D), the conductivity ratio between the first and second layers (C1,/C2,), the conductivity contrast of the dyke (C/C2,), and the width (W ), length (L ) and dip angle of the dyke (A), are used. Various groups of magnetotelluric field components and their transformations are studied in order to estimate the effect of the data type used on the ANN recognition ability. It is found that use of only the xy - and yx -components of impedance phases results in reasonable recognition errors for all unknown parameters (D: 0.02 per cent, C1/C2: 8.4 per cent, C/C2: 26.8 per cent, W : 0.02 per cent, L : 0.02 per cent, A: 0.24 per cent). The influence of the size and shape of the training data pool (including the ,gaps in education' and ,no target' effects) on the recognition properties is studied. Results from numerous ANN tests demonstrate that the ANN possesses good enough interpolation and extrapolation abilities if the training data pool contains a sufficient number of representative data sets. The effect of noise is estimated by means of mixing the synthetic data with 30, 50 and 100 per cent Gaussian noise. The unusual behaviour of the recognition errors for some of the model parameters when the data become more noisy (in particular, the fact that an increase in error is followed by a decrease) indicates that the use of standard techniques of noise reduction may give an opposite result, so the development of a special noise treatment methodology is required. Thus, it is shown that ANN-based recognition can be successfully used for inversion if the data correspond to the model class familiar to the ANN. No initial guess regarding the parameters of the 3-D target or 1-D layering is required. The ability of the ANN to teach itself using real geophysical (not only electromagnetic) data measured at a given location over a sufficiently long period means that there is the potential to use this approach for interpreting monitoring data. [source] Dynamical effects of the statistical structure of annual rainfall on dryland vegetationGLOBAL CHANGE BIOLOGY, Issue 5 2006CHRISTOPHER A. WILLIAMS Abstract In this study, we extend a model of daily dryland dynamics by parameterizing a modified version of a minimalistic annual model to examine how the statistical structure of annual rainfall and grazing intensity interact to influence dryland vegetation. With a Monte Carlo approach, an ensemble outcome provides a statistical description of likely dryland vegetation dynamics responding to variations in rainfall structure and grazing intensity. Results suggest that increased rainfall variability decreases the average and increases the variability of grass cover leading to more frequent degradation of the grass resource. Vegetation of drier regions is found to be more sensitive to interannual variability in rainfall. Concentrating this variability into an organized periodic mode further decreases the mean and increases the variability of grass cover. Hence, a shift toward lower, more variable, or more inter-annually correlated annual rainfall will likely lead to a general decrease in the grass resource and increased dryland vulnerability to degradation. Higher grazing intensity or lower annual rainfall both lead to more frequent and longer duration degradation of the grass condition. We note an interesting interaction in the response of grass biomass to grazing intensity and rainfall variability, where increased rainfall variability leads to longer duration degradation for low grazing, but shorter periods of degradation for high grazing. Once grass reaches a degraded condition, we find that woody vegetation strongly suppresses recovery even if successive rainfall is high. Overall, these findings suggest that the projected increase in interannual rainfall variability will likely decrease grass cover and potentially lead to more frequent, longer lasting degradation of dryland vegetation, particularly if enhanced rainfall variability is concentrated in long period (e.g. decadal) modes. [source] Constraining the Sheffield dynamic global vegetation model using stream-flow measurements in the United KingdomGLOBAL CHANGE BIOLOGY, Issue 12 2005G. Picard Abstract The biospheric water and carbon cycles are intimately coupled, so simulating carbon fluxes by vegetation also requires modelling of the water fluxes, with each component influencing the other. Observations of river streamflow integrate information at the catchment scale and are widely available over a long period; they therefore provide an important source of information for validating or calibrating vegetation models. In this paper, we analyse the performance of the Sheffield dynamic global vegetation model (SDGVM) for predicting river streamflow and quantifying how this information helps to constrain carbon flux predictions. The SDGVM is run for 29 large catchments in the United Kingdom. Annual streamflow estimates are compared with long time-series observations. In 23 out of the 29 catchments, the bias between model and observations is less than 50 mm, equivalent to less than 10% of precipitation. In the remaining catchments, larger errors are because of combinations of unpredictable causes, in particular various human activities and measurement issues and, in two cases, unidentified causes. In one of the catchments, we assess to what extent a knowledge of annual streamflow can constrain model parameters and in turn constrain estimates of gross primary production (GPP). For this purpose, we assume the model parameters are uncertain and constrain them by the streamflow observations using the generalized likelihood uncertainty estimation method. Comparing the probability density function of GPP with and without constraint shows that streamflow effectively constrains GPP, mainly by setting a low probability to GPP values below about 1100 g C,1 m2 yr,1. In other words, streamflow observations allow the rejection of low values of GPP, so that the potential range of possible GPP values is almost halved. [source] Geographical and taxonomic influences on cranial variation in red colobus monkeys (Primates, Colobinae): introducing a new approach to ,morph' monkeysGLOBAL ECOLOGY, Issue 2 2009Andrea Cardini ABSTRACT Aim, To provide accurate but parsimonious quantitative descriptions of clines in cranial form of red colobus, to partition morphological variance into geographical, taxonomic and structured taxonomic components, and to visually summarize clines in multivariate shape data using a method which produces results directly comparable to both univariate studies of geographical variation and standard geometric morphometric visualization of shape differences along vectors. Location, Equatorial Africa. Methods, Sixty-four three-dimensional cranial landmarks were measured on 276 adult red colobus monkeys sampled over their entire distribution. Geometric morphometric methods were applied, and size and shape variables regressed onto geographical coordinates using linear and curvilinear models. Model selection was done using the second-order Akaike information criterion. Components of variation related to geography, taxon or their combined effect were partitioned using partial regresssion. Multivariate trends in clinal shape were summarized using principal components of predictions from regressions, plotting vector scores on maps as for univariate size, and visualizing differences along main axes of clinal shape variation using surface rendering. Results, Significant clinal variation was found in size and shape. Clines were similar in females and males. Trend surface analysis tended to be more accurate and parsimonious than alternative models in predicting morphology based on geography. Cranial form was relatively paedomorphic in East Africa and peramorphic in central Africa. Most taxonomic variation was geographically structured. However, taxonomic differences alone accounted for a larger proportion of total explained variance in shape (up to 40%) than in size (, 20%). Main conclusions, A strong cline explained most of the observed size variation and a significant part of the shape differences of red colobus crania. The pattern of geographical variation was largely similar to that previously reported in vervets, despite different habitat preferences (arboreal versus terrestrial) and a long period since divergence (c. 14,15 Myr). This suggests that some aspects of morphological divergence in both groups may have been influenced by similar environmental, geographical and historical factors. Cranial size is likely to be evolutionarily more labile and thus better reflects the influence of recent environmental changes. Cranial shape could be more resilient to change and thus better reflects phylogenetically informative differences. [source] The Impact of Trade Liberalization on Regional Disparities in MexicoGROWTH AND CHANGE, Issue 1 2002Javier Sánchez-Reaza After a long period of industrialization based on import substitution (ISI), Mexico started to open up its economy by accessing the General Agreement on Tariffs and Trade (GATT) in 1986. The export-promotion strategy was transformed into one of regional integration with the signing of the North American Free Trade Agreement (NAFTA) in 1994. The paper explores the impact of the opening of the economy on regional disparities in Mexico using , and ,-convergence analyses. Four different samples have been employed to control for possible data bias linked to the inclusion of oil-producing and maquiladora-based states. The results show that whereas the final stages of the ISI period were dominated by convergence trends, trade liberalization (GATT) and economic integration (NAFTA) have led to divergence. In particular, the NAFTA period is related to divergence regardless of the type of analysis chosen and the sample used. [source] ,Taking off the suit': engaging the community in primary health care decision-makingHEALTH EXPECTATIONS, Issue 1 2006Elizabeth Anderson MSc RGN Abstract Objective, To explore the process of public involvement in planning primary health care. Background, Recent policy in the UK promotes public involvement in planning health but there have been difficulties in engaging communities in the process. Surveys of health service organizations have found that there has been a failure to adapt to new approaches. It has become important to understand why this has occurred if policy initiatives to encourage involvement are to succeed. Design, Qualitative study. Data collected through individual interviews and focus groups. Setting, Two new primary healthcare developments in deprived areas in Bristol and Weston-Super-Mare. Participants, Thirty-six professionals and 23 local residents in Bristol; six professionals and three local residents in Weston-Super-Mare. Results, Three themes were identified: process, partnership and power. The main findings were that exceptional people with a shared commitment to public involvement were necessary to motivate others and develop partnerships. Local people were drawn into the process and with increased confidence became powerful advocates for their community. Creative and varied methods to involve the public were important in achieving balance between professionals and lay people. However, conflicts over practical decisions arose from a lack of clarity over who had power to influence decisions. Conclusion, Most of the participants were enthusiastic about their experience of public involvement in planning primary health care. Features crucial to sustainable involvement included a commitment from leaders within statutory agencies, support over a long period to build the confidence of local people, willingness to use informal approaches that are in tune with local culture, and a recognition of the concerns of both service users and providers. [source] The assessment of surface water resources for the semi-arid Yongding River Basin from 1956 to 2000 and the impact of land use changeHYDROLOGICAL PROCESSES, Issue 9 2010Lei Wang Abstract The assessment of surface water resources (SWRs) in the semi-arid Yongding River Basin is vital as the basin has been in a continuous state of serious water shortage over the last 20 years. In this study, the first version of the geomorphology-based hydrological model (GBHM) has been applied to the basin over a long period of time (1956,2000) as part of an SWR assessment. This was done by simulating the natural hydrological processes in the basin. The model was first evaluated at 18 stream gauges during the period from 1990 to 1992 to evaluate both the daily streamflows and the annual SWRs using the land use data for 1990. The model was further validated in 2000 with the annual SWRs at seven major stream gauges. Second, the verified model was used in a 45-year simulation to estimate the annual SWRs for the basin from 1956 to 2000 using the 1990 land use data. An empirical correlation between the annual precipitation and the annual SWRs was developed for the basin. Spatial distribution of the long-term mean runoff coefficients for all 177 sub-basins was also achieved. Third, an additional 10-year (1991,2000) simulation was performed with the 2000 land use data to investigate the impact of land use changes from 1990 to 2000 on the long-term annual SWRs. The results suggest that the 10-year land use changes have led to a decrease of 8·3 × 107 m3 (7·9% of total) for the 10-year mean annual SWRs in the simulation. To our knowledge, this work is the first attempt to assess the long-term SWRs and the impact of land use change in the semi-arid Yongding River Basin using a semi-distributed hillslope hydrological model. Copyright © 2010 John Wiley & Sons, Ltd. [source] Sodium channel gene expression in mosquitoes, Aedes albopictus (S.)INSECT SCIENCE, Issue 6 2006NANNAN LIU Abstract A mosquito strain of Aedes albopictus, HAmAalG0, from Huntsville, Alabama, USA, showed a normal susceptibility and low tolerance to permethrin and resmethrin (pyrethroid insecticides) compared to a susceptible Ikaken strain, even though these pyrethroid insecticides have been used in the field for a long period of time in Alabama. Recently, we treated HAmAalG0 in the laboratory with permethrin for five generations and detected no significant change in the level of resistance to permethrin in the selected mosquitoes, HAmAalG5, compared with the parental strain HAmAalG0. We then examined the allelic expression at the L-to-F kdr site of the sodium channel gene in the Aedes mosquitoes to address our hypothesis that the L-to-F kdr mutation was not present in HAmAalG0 and HAmAalG5 mosquitoes. We found that every tested individual in Ikaken, HAmAalG0, and HAmAalG5 populations expressed a codon of CTA at the L-to-F kdr site encoding Leu, strongly corresponding to their susceptibility to insecticides. [source] Analytical solutions for dynamic pressures of coupling fluid,porous medium,solid due to SV wave incidenceINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 12 2009Jin-Ting Wang Abstract This paper presents the results of theoretical investigation on the dynamic coupling of an ideal fluid-porous medium-elastic half-space system subjected to SV waves to study the effect of sediment on the seismic response of dams for reservoirs that are deposited with a significant amount of sediment after a long period of operation. The effects of the porous medium and the incident wave angle on dynamic pressures in the overlying ideal fluid are analyzed, and the reflection and transmission coefficients of the wave at the material interfaces are derived using an analytical solution in terms of displacement potentials. The numerical test of modeling shows that the dynamic pressures significantly depend on the properties of porous medium. The fully saturated porous medium reduces the response peaks slightly, while the partially saturated porous medium causes a considerable increase in the resonance peaks. Copyright © 2009 John Wiley & Sons, Ltd. [source] Infancy is not a quiescent period of testicular developmentINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 1 2001Héctor E. Chemes Postnatal evolution of the testis in most laboratory animals is characterized by the close continuity between neonatal activation and pubertal development. In higher primates, infancy, a long period of variable duration, separates birth from the beginning of puberty. This period has been classically considered as a quiescent phase of testicular development, but is actually characterized by intense, yet inapparent activity. Testicular volume increases vigorously shortly after birth and in early infancy due to the growth in length of seminiferous cords. This longitudinal growth results from active proliferation of infantile Sertoli cells which otherwise display a unique array of functional capabilities (oestrogen and anti-müllerian hormone secretion, increase of FSH receptors and maximal response to FSH). Leydig cells also show recrudescence after birth, possibly determined by an active gonadotrophic-testicular axis which results in increased testosterone secretion of uncertain functional role. This postnatal activation slowly subsides during late infancy when periodic phases of activation of the hypothalamo-pituitary-testicular axis are paralleled by incomplete spermatogenic spurts. The beginning of puberty is marked by the simultaneous reawakening of Leydig cell function and succeeding phases of germ cell differentiation/degeneration which ultimately lead to final spermatogenic maturation. The marked testicular growth in this stage is due to progressive increase at seminiferous tubule diameter. Sertoli cells, which have reached mitotic arrest, develop and differentiate, establishing the seminiferous tubule barrier, fluid secretion and lumen formation, and acquiring cyclic morphological and metabolic variations characteristic of the mature stage. All of these modifications indicate that, far from being quiescent, the testis in primates experiences numerous changes during infancy, and that the potential for pubertal development and normal adult fertility depends on the successful completion of these changes. [source] Pre-rainy season moisture build-up and storm precipitation delivery in the West African SahelINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 7 2008J. Bayo Omotosho Abstract The salient differences between the years of above and below normal precipitation, particularly within the long period of 1972,1990 with persistently decreasing Sahelian rainfall, are investigated for Kano, a Nigerian station within the Sahel. Daily rainfall data from 1916 to 2000, storm records from 1951 to 2000 and radiosonde data for three dry and three wet years are used in this study. Results confirm previous findings that the African Easterly Jet (AEJ) located in the 700,600 mb layer is stronger during the dry than in wet years. Significantly, however, it is shown that during the wet years, there is stronger and deeper early season (April,June) build-up of moisture below the AEJ. Furthermore, throughout the period from April to August, the middle troposphere was almost always drier than normal during the dry years and moist than normal in the wet years. Consequent upon these, the storms, which deliver almost all the rainfall in the Sahel, produce at least 150% more precipitation during the wet than in the dry years, though the June to September or annual total number of storms differs by only about 30%. Finally, during the dry years, the onset of rainfall is found to be generally very late compared to the long-term mean, with shorter length of the rainy season. Copyright © 2007 Royal Meteorological Society [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||