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Scarce
Kinds of Scarce Terms modified by Scarce Selected AbstractsTHINGS BECAME SCARCE: FOOD AVAILABILITY AND ACCESSIBILITY IN SANTIAGO de CUBA THEN AND NOWANNALS OF ANTHROPOLOGICAL PRACTICE, Issue 1 2009Hanna Garth Cuba has had a nationalized food rationing system since 1962, and has been lauded for exemplary food security innovations in the face of national financial hardship. Decreases in food and agricultural related importations after the collapse of the Soviet Union in 1990 limited the amount of food provided in the monthly rations, forcing individuals to acquire increasing amounts of their food through other means. This article reveals the complexities Cubans face when attempting to access foods in Santiago de Cuba. This project examines how Cubans experience their food system, their struggles to maintain food traditions despite the low availability of ingredients, and how people use and relate to Cuba's food provisioning system. In this article two memories of past periods of abundance are juxtaposed to show the different ways in which individuals interpret food security. The analysis of semistructured interviews, community mapping, and participant-observation reveal the ways in which residents of Santiago de Cuba orient to their present situation through memories of past periods when foods were more available and more easily accessible. [source] Molecular Editing and Biological Evaluation of Amphidinolide X and YCHEMISTRY - A EUROPEAN JOURNAL, Issue 16 2009Alois Fürstner Prof. Abstract Scarce and precious: A collection of compounds with deep-seated structural "point mutations" within the framework of the marine natural products amphidinolide X and Y was prepared by "diverted total synthesis". The resulting products provided first insights into the cytotoxicity profile of these extremely scarce macrolides. Deliberate deviations from the previously described total syntheses of amphidinolide X (1) and Y (2) allowed a collection of seven designed analogues of these extremely scarce marine natural products to be obtained. These fully synthetic "natural product-like" compounds enabled first insights into the previously unknown structure,activity relationships governing this series. Although the average cytotoxicity is moderate, it was found that certain bladder, colon and prostate cancer cell lines are fairly sensitive, and that the best synthetic analogues are more active than the natural products themselves. The syntheses rely on the 9-MeO-9-BBN variant of the Suzuki coupling for the formation of the carbon frameworks, as well as on Yamaguchi lactonization reactions for the cyclization of the macrocyclic rings. [source] Comparison of Neural Networks and Gravity Models in Trip DistributionCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 2 2006Frans Tillema Modeling the distribution of trips between zones is complex and dependent on the quality and availability of field data. This research explores the performance of neural networks in trip distribution modeling and compares the results with commonly used doubly constrained gravity models. The approach differs from other research in several respects; the study is based on both synthetic data, varying in complexity, as well as real-world data. Furthermore, neural networks and gravity models are calibrated using different percentages of hold out data. Extensive statistical analyses are conducted to obtain necessary sample sizes for significant results. The results show that neural networks outperform gravity models when data are scarce in both synthesized as well as real-world cases. Sample size for statistically significant results is forty times lower for neural networks. [source] Congenital malformations in infants whose mothers reported the use of folic acid in early pregnancy in Sweden.CONGENITAL ANOMALIES, Issue 4 2007A prospective population study ABSTRACT The use of folic acid prior to conception is generally recommended for the prevention of birth defects, notably neural tube defects. In a previous study from Sweden, based on interviews of women in early pregnancy, no such effect was found on the general malformation rate, but data for neural tube defects were scarce. Using data from the Swedish Medical Birth Register for the years 1995,2004, 20 891 women were identified who reported the use of folic acid in early pregnancy, but not of anticonvulsants. These women were compared to all other women who gave birth during the study period. Malformations in the infants born were identified from multiple sources. No reduction in the general malformation rate was seen among infants born to women who reported the use of folic acid (OR = 1.09, 95% CI 1.02,1.17) and no effect of neural tube defect rate was seen (RR = 1.35, 95% CI 0.82,2.22), based on 16 infants with neural tube defect whose mother reported the use of folic acid. No effect was seen on the rates of other malformations except for cardiac defects, where a statistically significant increased risk (notably for severe defects) was found (OR = 1.19, 95% CI 1.05,1.35). The effect of various deficiencies in data collection is discussed, but is unlikely to explain the lack of protective effect noticed. So far, it has not been possible to demonstrate a beneficial effect of folic acid supplementation on malformation risk in Sweden. A more complete ascertainment and detailed timing and dosage of folic acid use in a prospective study is recommended. [source] Providers' Beliefs, Attitudes, and Behaviors before Implementing a Computerized Pneumococcal Vaccination ReminderACADEMIC EMERGENCY MEDICINE, Issue 12 2006Judith W. Dexheimer MS Abstract Background The emergency department (ED) has been recommended as a suitable setting for offering pneumococcal vaccination; however, implementations of ED vaccination programs remain scarce. Objectives To understand beliefs, attitudes, and behaviors of ED providers before implementing a computerized reminder system. Methods An anonymous, five-point Likert-scale, 46-item survey was administered to emergency physicians and nurses at an academic medical center. The survey included aspects of ordering patterns, implementation strategies, barriers, and factors considered important for an ED-based vaccination initiative as well as aspects of implementing a computerized vaccine-reminder system. Results Among 160 eligible ED providers, the survey was returned by 64 of 67 physicians (96%), and all 93 nurses (100%). The vaccine was considered to be cost effective by 71% of physicians, but only 2% recommended it to their patients. Although 98% of physicians accessed the computerized problem list before examining the patient, only 28% reviewed the patient's health-maintenance section. Physicians and nurses preferred a computerized vaccination-reminder system in 93% and 82%, respectively. Physicians' preferred implementation approach included a nurse standing order, combined with physician notification; nurses, however, favored a physician order. Factors for improving vaccination rates included improved computerized documentation, whereas increasing the number of ED staff was less important. Relevant implementation barriers for physicians were not remembering to offer vaccination, time constraints, and insufficient time to counsel patients. The ED was believed to be an appropriate setting in which to offer vaccination. Conclusions Emergency department staff had favorable attitudes toward an ED-based pneumococcal vaccination program; however, considerable barriers inherent to the ED setting may challenge such a program. Applying information technology may overcome some barriers and facilitate an ED-based vaccination initiative. [source] Capability, Quality, and Performance of Offshore IS Vendors: A Theoretical Framework and Empirical InvestigationDECISION SCIENCES, Issue 2 2010Prashant C. Palvia ABSTRACT Information systems (IS) offshoring has become a widespread practice and a strategic sourcing choice for many firms. While much has been written by researchers about the factors that lead to successful offshoring arrangements from the client's viewpoint, the vendor's perspective has been largely scarce. The vendor perspective is equally important as offshore IS vendors need to make important decisions in terms of delivering operational and strategic performance and aligning their resources and processes in order to meet or exceed targeted outcomes. In this article, we propose and test a three-level capability,quality,performance (CQP) theoretical framework to understand vendor outcomes and their antecedents. The first level of the framework represents three vendor capabilities: relationship management, contract management, and information technology management. The second level has three mediating variables representing process quality: partnership, service, and deliverable quality. The third level has three dependent variables representing vendor outcomes: operational performance, strategic performance, and satisfaction. The model was tested with 188 vendor firms from India and China, the two most popular destinations for IS offshoring. Results support the CQP framework; vendor capabilities are significant predictors of intermediate quality measures, which in turn affect vendor outcomes. Implications of the study findings to both theory development and IS offshore vendor strategic decision making are discussed. [source] Prevalence and predictors of recurrence of major depressive disorder in the adult populationACTA PSYCHIATRICA SCANDINAVICA, Issue 3 2010F. Hardeveld Hardeveld F, Spijker J, De Graaf R, Nolen WA, Beekman ATF. Prevalence and predictors of recurrence of major depressive disorder in the adult population. Objective:, Knowledge of the risk of recurrence after recovery of a major depressive disorder (MDD) is of clinical and scientific importance. The purpose of this paper was to provide a systematic review of the prevalence and predictors of recurrence of MDD. Method:, Studies were searched in Medline en PsychINFO using the search terms ,recur*', ,relaps*', ,depress*', ,predict*' and course. Results:, Recurrence of MDD in specialised mental healthcare settings is high (60% after 5 years, 67% after 10 years and 85% after 15 years) and seems lower in the general population (35% after 15 years). Number of previous episodes and subclinical residual symptoms appear to be the most important predictors. Gender, civil status and socioeconomic status seem not related to the recurrence of MDD. Conclusion:, Clinical factors seem the most important predictors of recurrence. Data from studies performed in the general population and primary care on the recurrent course of MDD are scarce. [source] Comparison of Long-Pulsed Diode and Long-Pulsed Alexandrite Lasers for Hair Removal: A Long-Term Clinical and Histologic StudyDERMATOLOGIC SURGERY, Issue 7 2001Christiane Handrick MD Background. Unwanted facial and body hair is a common problem, generating a high level of interest for treatment innovations. Advances in laser technology over the past several years has led to the development and distribution of numerous red and infrared lasers and light sources to address this issue. Despite the impressive clinical results that have been reported with the use of individual laser hair removal systems, long-term comparative studies have been scarce. Objective. To compare the clinical and histologic efficacy, side effect profile, and long-term hair reduction of long-pulsed diode and long-pulsed alexandrite laser systems. Methods. Twenty women with Fitzpatrick skin types I,IV and dark terminal hair underwent three monthly laser-assisted hair removal sessions with a long-pulsed alexandrite laser (755 nm, 2-msec pulse, 10 mm spot) and a long-pulsed diode laser (800 nm, 12.5 msec or 25 msec, 9 mm spot). Axillary areas were randomly assigned to receive treatment using each laser system at either 25 J/cm2 or 40 J/cm2. Follow-up manual hair counts and photographs of each area were obtained at each of the three treatment visits and at 1, 3, and 6 months after the final laser session. Histologic specimens were obtained at baseline, immediately after the initial laser treatment, and 1 and 6 months after the third treatment session. Results. After each laser treatment, hair counts were successively reduced and few patients found it necessary to shave the sparsely regrown hair. Optimal clinical response was achieved 1 month after the second laser treatment, regardless of the laser system or fluence used. Six months after the third and final treatment, prolonged clinical hair reduction was observed with no significant differences between the laser systems and fluences used. Histologic tissue changes supported the clinical responses observed with evidence of initial follicular injury followed by slow follicular regeneration. Side effects, including treatment pain and vesiculation, were rare after treatment with either laser system, but were observed more frequently with the long-pulsed diode system at the higher fluence of 40 J/cm2. Conclusion. Equivalent clinical and histologic responses were observed using a long-pulsed alexandrite and a long-pulsed diode laser for hair removal with minimal adverse sequelae. While long-term hair reduction can be obtained in most patients after a series of laser treatments, partial hair regrowth is typical within 6 months, suggesting the need for additional treatments to improve the rate of permanent hair removal. [source] Proving our value: Measuring package design's Return On InvestmentDESIGN MANAGEMENT REVIEW, Issue 3 2001Rob Wallace Since resources are scarce, it makes sense to allocate budgets in ways that generate the highest yields. In the arena of consumer awareness and influencing the decision to purchase, Rob Wallace makes the case that money spent on package design results in an outstanding return on investment. He outlines a methodology to quantify this return, and challenges design management colleagues to refine the calculus. [source] Patterning the heart, a template for human cardiomyocyte developmentDEVELOPMENTAL DYNAMICS, Issue 7 2006Susana M. Chuva de Sousa Lopes Abstract Although in mice, the dynamics of gene expression during heart development is well characterized, information on humans is scarce due to the limited availability of material. Here, we analyzed the transcriptional distribution of Mlc-2a, Mlc-1v, Mlc-2v, and atrial natriuretic factor (ANF) in human embryonic hearts between 7 and 18 weeks of gestation and in healthy and hypertrophic adult hearts by in situ hybridization and compared expression with that in mice. Strikingly, Mlc-2a, Mlc-1v, and ANF, which are essentially chamber-restricted in mice by mid-gestation, showed a broader distribution in humans. On the other hand, Mlc-2v may prove to be an adequate ventricular marker in humans in contrast to mouse. This study emphasizes the importance of careful comparative human,animal analyses during embryonic development and adulthood, as avoiding erroneous extrapolations may be critical to develop new and successful myocardial replacement therapies. Development Dynamics 235:1994,2002, 2006. © 2006 Wiley-Liss, Inc. [source] Autophagic pathways and metabolic stressDIABETES OBESITY & METABOLISM, Issue 2010S. Kaushik Autophagy is an essential intracellular process that mediates degradation of intracellular proteins and organelles in lysosomes. Autophagy was initially identified for its role as alternative source of energy when nutrients are scarce but, in recent years, a previously unknown role for this degradative pathway in the cellular response to stress has gained considerable attention. In this review, we focus on the novel findings linking autophagic function with metabolic stress resulting either from proteins or lipids. Proper autophagic activity is required in the cellular defense against proteotoxicity arising in the cytosol and also in the endoplasmic reticulum, where a vast amount of proteins are synthesized and folded. In addition, autophagy contributes to mobilization of intracellular lipid stores and may be central to lipid metabolism in certain cellular conditions. In this review, we focus on the interrelation between autophagy and different types of metabolic stress, specifically the stress resulting from the presence of misbehaving proteins within the cytosol or in the endoplasmic reticulum and the stress following a lipogenic challenge. We also comment on the consequences that chronic exposure to these metabolic stressors could have on autophagic function and on how this effect may underlie the basis of some common metabolic disorders. [source] The value of debridement and Vacuum-Assisted Closure (V.A.C.) Therapy in diabetic foot ulcersDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue S1 2008Magnus Eneroth Abstract Background Treatment of diabetic foot ulcers includes a number of different regimes such as glycaemic control, re-vascularization, surgical, local wound treatment, offloading and other non-surgical treatments. Although considered the standard of care, the scientific evidence behind the various debridements used is scarce. This presentation will focus on debridement and V.A.C. Therapy, two treatments widely used in patients with diabetes and foot ulcers. Methods A review of existing literature on these treatments in diabetic foot ulcers, with focus on description of the various types of debridements used, the principles behind negative pressure wound therapy (NPWT) using the V.A.C. Therapy system and level of evidence. Results Five randomized controlled trials (RCT) of debridement were identified; three assessed the effectiveness of a hydrogel as a debridement method, one evaluated surgical debridement and one evaluated larval therapy. Pooling the three hydrogel RCTs suggested that hydrogels are significantly more effective than gauze or standard care in healing diabetic foot ulcers. Surgical debridement and larval therapy showed no significant benefit. Other debridement methods such as enzyme preparations or polysaccharide beads have not been evaluated in RCTs of people with diabetes. More than 300 articles have been published on negative pressure wound therapy, including several small RCTs and a larger multi-centre RCT of diabetic foot ulcers. Negative pressure wound therapy seems to be a safe and effective treatment for complex diabetic foot wounds, and could lead to a higher proportion of healed wounds, faster healing rates, and potentially fewer re-amputations than standard care. Conclusions Although debridement of the ulcer is considered a prerequisite for healing of diabetic foot ulcers, the grade of evidence is quite low. This may be due to a lack of studies rather than lack of effect. Negative pressure wound therapy seems to be safe and effective in the treatment of some diabetic foot ulcers, although there is still only one well-performed trial that evaluates the effect. Copyright © 2008 John Wiley & Sons, Ltd. [source] Coexistent atypical polypoid adenomyoma and complex atypical endometrial hyperplasia in the uterusDIAGNOSTIC CYTOPATHOLOGY, Issue 7 2010Ayako Horita M.D. Abstract We report a case of atypical polypoid adenomyoma (APA) concomitantly identified with complex atypical endometrial hyperplasia (CAH) in the uterus. Since an initial endometrial smear revealed atypical endometrial cells, a diagnosis of CAH was made. Even though a concomitantly performed uterine cervical smear contained both atypical epithelial and stromal cells, the diagnosis of APA was not initially made because the cytological criteria for APA had not been established. Histologically, we recognized both CAH in the uterine corpus and APA in the lower uterine segment in the hysterectomy material. Retrospectively, the cells in the first cervical smear were interpreted as part of APA because the same types of cells were observed in the intraoperative cytology sample. Although the APA and CAH lesions were interposed by normal endometrium, estrogen was suspected to be the common etiological factor. Reports regarding the cytology of APA are currently scarce. To our knowledge, this is the first report showing cytological presentation of association of APA with CAH in addition to the first cervical smear of APA containing both epithelial and stromal components. Identification of abnormal proliferation of epithelium and stromal cells of smooth muscle origin is useful in the cytological diagnosis of APA. Diagn. Cytopathol. 2010. © 2009 Wiley-Liss, Inc. [source] Phylogenetic relatedness and plant invader success across two spatial scalesDIVERSITY AND DISTRIBUTIONS, Issue 3 2009Marc W. Cadotte ABSTRACT Aim, Successful invaders often possess similar ecological traits that contribute to success in new regions, and thus under niche conservatism, invader success should be phylogenetically clustered. We asked if the degree to which non-native plant species are phylogenetically related is a predictor of invasion success at two spatial scales. Location, Australia , the whole continent and Royal National Park (south-eastern Australia). Methods, We used non-native plant species occupancy in Royal National Park, as well as estimated continental occupancy of these species from herbarium records. We then estimated phylogenetic relationships using molecular data from three gene sequences available on GenBank (matK, rbcL and ITS1). We tested for phylogenetic signals in occupancy using Blomberg's K. Results, Whereas most non-native plants were relatively scarce, there was a strong phylogenetic signal for continental occupancy, driven by the clustering of successful species in Asteraceae, Caryophyllaceae, Poaceae and Solanaceae. However, we failed to detect a phylogenetic signal at the park scale. Main Conclusions, Our results reveal that at a large spatial scale, invader success is phylogenetically clustered where ecological traits promoting success appear to be shared among close relatives, indicating that phylogenetic relationships can be useful predictors of invasion success at large spatial scales. At a smaller, landscape scale, there was no evidence of phylogenetic clustering of invasion success, and thus, relatedness plays a much reduced role in determining the relative success of invaders. [source] Mutualism as a constraint on invasion success for legumes and rhizobiaDIVERSITY AND DISTRIBUTIONS, Issue 3 2001Matthew A. Parker Abstract Because hereditary symbiont transmission is normally absent in the mutualism of legume plants and root-nodule bacteria (rhizobia), dispersing plants may often arrive at new habitats where mutualist partners are too rare to provide full benefits. Factors governing invasion success were explored by analysing a system of two coupled pairwise competition models: a legume invader competing with a resident non-mutualistic plant, and a rhizobial population competing with a resident population of nonsymbiotic bacteria. The non-linear dependence of benefits on partner abundance in this mutualism creates the possibility of two alternative population size equilibria, so that a threshold density can exist for invasion. If legumes and rhizobia exceed a critical population size, both species achieve rapid population growth, while if initial densities of both species are below their respective thresholds, they remain rare and are thus vulnerable to extinction in the presence of competitors. Overall, the results indicate that legumes may often fail at colonization attempts within habitats where mutualist partners are scarce. Data on legume prevalence in island floras and rates of geographical spread by legume weeds are consistent with this inference. Predictive insights about invasiveness may emerge from comparative research on key traits identified by the model, especially the shape of the function determining the number of nodules formed at low rhizobial density. [source] Field-based and spectral indicators for soil erosion mapping in semi-arid mediterranean environments (Coastal Cordillera of central Chile)EARTH SURFACE PROCESSES AND LANDFORMS, Issue 1 2007Renaud Mathieu Abstract The Coastal Cordillera of central Chile is naturally sensitive to soil erosion due to moderate to steep slopes, intense winter rains when the vegetation cover is scarce, and deeply weathered granitic rocks. In 1965, 60 per cent of its surface was moderately to very severely eroded. Today this process is still largely active, but no data are currently available to evaluate the real extent, distribution and severity of soil degradation on a regional scale. This information is vital to support efficient soil conservation plans. A multi-scale approach was implemented to produce regional land degradation maps based on remote sensing technologies. Fieldwork has shown that the surface colour or ,redness' and the density of coarse fragments are pertinent erosion indicators to describe a typical sequence of soil degradation in the context of mediterranean soil developed on granitic materials and micaschists. Field radiometric experiments concluded that both factors influence the reflectance of natural surfaces and can be modelled using radiometric indices accessible from most satellites operating in the optical domain, i.e. redness index and brightness index. Finally the radiometric indices were successfully applied to SPOT images to produce land degradation maps. Only broad classes of erosion status were discriminated and the detection of the degradation processes was only possible when most of the fertile layer had already been removed. This technology provides decision-making information required to develop regional soil conservation plans and to prioritize actions between catchment areas, especially in vast inter-tropical regions where spatialized data are not always readily available. Copyright © 2006 John Wiley & Sons, Ltd. [source] The Global Diversion of Pharmaceutical DrugsADDICTION, Issue 9 2010Opiate treatment, the diversion of pharmaceutical opiates: a clinician's perspective ABSTRACT Aim To provide a clinician's perspective on the problem of diversion of prescribed pharmaceuticals. Methods The paper provides a personal account of working in a treatment context where diversion from opioid substitution treatment (OST) became a political issue potentially compromising the continued delivery of OST. It summarizes evidence on the impact of diversion, and measures to contain it, from the United Kingdom 1986,2006, Australia 1996,2008 and the United States and France from the mid-1990s. Results Opioid diversion to the black market occurs in proportion to the amount of opioids prescribed to be taken without supervision, and in inverse proportion to the availability of heroin. Diversion for OST programmes using supervision of dosing is less than diversion of opioids prescribed for pain, which is now a growing public health problem. Adverse consequences of diversion include opioid overdose fatalities, an increased incidence of addiction (particularly in jurisdictions where heroin is scarce) and compromising the public acceptance of long-term opioid prescribing. All long-term opioid prescribing requires monitoring of risk and appropriate dispensing arrangements,including dilution of methadone take-aways, supervision of administration for high-risk patients and random urine testing. Clinical guidelines influence practice, although prescribing often deviates from guidelines. Conclusion Clinical guidelines and clinical audit to enhance compliance with guidelines are helpful in maintaining the quality and integrity of the treatment system, and can contribute to keeping diversion within acceptable levels. [source] Sexual patterns of prebreeding energy reserves in the common frog Rana temporaria along a latitudinal gradientECOGRAPHY, Issue 5 2009K. Ingemar Jönsson The ability to store energy is an important life history trait for organisms facing long periods without energy income, and in particular for capital breeders such as temperate zone amphibians, which rely on stored energy during reproduction. However, large scale comparative studies of energy stores in populations with different environmental constraints on energy allocation are scarce. We investigated energy storage patterns in spring (after hibernation and before reproduction) in eight common frog Rana temporaria populations exposed to different environmental conditions along a 1600,km latitudinal gradient across Scandinavia (range of annual activity period is 3,7,months). Analyses of lean body weight (eviscerated body mass), weight of fat bodies, liver weight, and liver fat content, showed that 1) post-hibernation/pre-breeding energy stores increased with increasing latitude in both sexes, 2) males generally had larger energy reserves than females and 3) the difference in energy stores between sexes decreased towards the north. Larger energy reserves towards the north can serve as a buffer against less predictable and/or less benign weather conditions during the short activity period, and may also represent a risk-averse tactic connected with a more pronounced iteroparous life history. In females, the continuous and overlapping vitellogenic activity in the north may also demand more reserves in early spring. The general sexual difference could be a consequence of the fact that, at the time of our sampling, females had already invested their energy into reproduction in the given year (i.e. their eggs were already ovulated), while the males' main reproductive activities (e.g. calling, mate searching, sexual competition) occurred later in the season. [source] Distribution, abundance, and individual strategies: a multi-scale analysis of dasyurid marsupials in arid central AustraliaECOGRAPHY, Issue 3 2006Adele S. Haythornthwaite We investigated the effects of different environmental factors on the distribution and abundance of 6 species of dasyurid marsupials using a multiple-scale analysis. Data collected in the spinifex dunefields of the Simpson Desert, Australia, were analysed at 3 spatial scales spanning more than 5 orders of magnitude: "metasite" (covering an area of 1000,2000 km2), site (2,12 km2) and grid (0.01 km2). Temporal variability was also investigated, using data collected in March, April, and May in 4 consecutive years from 1997 to 2000. Both abiotic and biotic factors influenced the capture rates of different species at different times and spatial scales. At the coarsest spatial scale, Dasycercus cristicauda (mulgara) was consistently limited in its distribution by the intensity of rainfall, probably as an indirect result of increased grazing pressure from pastoral activity and a higher density of feral predators in high rainfall areas. However, at the finest spatial scale, this partly carnivorous species was scarce in areas of dense spinifex, perhaps because such habitats yield lowest returns during foraging, and was more common in areas where small invertebrate prey were abundant. Factors affecting the distribution of the most abundant dasyurid species in the study area, Sminthopsis youngsoni (lesser hairy-footed dunnart), could not be identified at any scale; we conclude that this reflects the opportunistic foraging strategies and flexible habitat requirements of this insectivorous species. Both Ningaui ridei (wongai ningaui) and Sminthopsis hirtipes (hairy-footed dunnart) were less abundant throughout the study region. For N. ridei, a spinifex specialist, predictors of occurrence could be identified only at the finest scale of analysis; at the grid level, a close positive association was detected in 2 of the 4 study years between capture rate and spinifex cover. For S. hirtipes, all 3 levels of spatial analysis revealed a negative association between capture rate and both rainfall and spinifex density. For the rarely-caught S. crassicaudata (fat-tailed dunnart) and Planigale tenuirostris (narrow-nosed planigale), no clear results were obtained at any spatial scale, and we interpret this to indicate that the study region represents sub-optimal habitat for these species. Given that different factors affected the distribution and abundance of dasyurids at different spatial scales over time, we conclude that a multiple-scale approach to population and community analysis is vital to accurately identify which environmental processes shape population and community dynamics. Understanding the interplay between regional and local processes will be crucial for management of existing species populations and for prediction of their distributions and abundances in future. [source] Larval cannibalism during the late developmental stages of a facultatively gregarious encyrtid endoparasitoidECOLOGICAL ENTOMOLOGY, Issue 6 2009ALEJANDRO TENA Abstract. 1The larvae of many gregarious parasitoid species are usually non-aggressive when they develop in or on a host, but those of Metaphycus flavus are one of the few exceptions known. Herein we describe their aggressive behaviour and the conditions under which it occurs, using observations in which larval development and physical conflict within parasitised and superparasitised hosts were mapped daily. 2Metaphycus flavus larvae often engaged in physical conflict that resulted in consumption of the losing larvae (= cannibalism ) in superparasitised hosts, whereas such conflict and consumption occurred rarely when a single brood developed in a host. 3Cannibalism among M. flavus larvae only occurred after the host resources had become scarce. Typically it occurred after the sixth day of development (fourth-instar larvae) when the larvae in a clutch had separated from their aeroscopic plate and were freed of their attachment to the host's cuticle. 4Female larvae in the initial clutch appeared more aggressive than male larvae when a second clutch was allocated 4 h after the first clutch. The probability of a larva being attacked and consumed by a brood mate increased as the number of larvae increased in the host. This partial tolerance might allow the members of the initial brood to defend themselves from offspring of a superparasitising female (= competitors ). Such post-ovipositional regulation of brood size might be interpreted as high-density intolerance among female offspring. [source] Host specificity of ambrosia and bark beetles (Col., Curculionidae: Scolytinae and Platypodinae) in a New Guinea rainforestECOLOGICAL ENTOMOLOGY, Issue 6 2007JIRI HULCR Abstract 1.,Bark and ambrosia beetles are crucial for woody biomass decomposition in tropical forests worldwide. Despite that, quantitative data on their host specificity are scarce. 2.,Bark and ambrosia beetles (Scolytinae and Platypodinae) were reared from 13 species of tropical trees representing 11 families from all major lineages of dicotyledonous plants. Standardised samples of beetle-infested twigs, branches, trunks, and roots were taken from three individuals of each tree species growing in a lowland tropical rainforest in Papua New Guinea. 3.,A total of 81 742 beetles from 74 species were reared, 67 of them identified. Local species richness of bark and ambrosia beetles was estimated at 80,92 species. 4.,Ambrosia beetles were broad generalists as 95% of species did not show any preference for a particular host species or clade. Similarity of ambrosia beetle communities from different tree species was not correlated with phylogenetic distances between tree species. Similarity of ambrosia beetle communities from individual conspecific trees was not higher than that from heterospecific trees and different parts of the trees hosted similar ambrosia beetle communities, as only a few species preferred particular tree parts. 5.,In contrast, phloeophagous bark beetles showed strict specificity to host plant genus or family. However, this guild was poor in species (12 species) and restricted to only three plant families (Moraceae, Myristicaceae, Sapindaceae). 6.,Local diversity of both bark and ambrosia beetles is not driven by the local diversity of trees in tropical forests, since ambrosia beetles display no host specificity and bark beetles are species poor and restricted to a few plant families. [source] Structure of two macrolepidopteran assemblages on Salix nigra (Marsh) and Acer negundo L.: abundance, diversity, richness, and persistence of scarce speciesECOLOGICAL ENTOMOLOGY, Issue 4 2000Pedro Barbosa Summary 1. Most insect species occur at low abundance but a greater research effort has been devoted to so-called outbreak species and little research is available on scarce (low abundance) species that are typical of most insect species. 2. Larval free-feeding macrolepidoptera of two riparian trees Salix nigra (Marsh) (black willow) and Acer negundo L. (box elder) were sampled and sorted by species and abundance. 3. Data collected established that the majority of species in the assemblages in each tree species occurred at low abundance in each of the 5 years when larvae were sampled. 4. Species in the Noctuidae and Geometridae dominated both assemblages. 5. On both trees, assemblages were dominated numerically by relatively few species, a pattern that has been observed for insect assemblages on plants in managed and unmanaged habitats. [source] Four ways towards tropical herbivore megadiversityECOLOGY LETTERS, Issue 4 2008Thomas M. Lewinsohn Abstract Most multicellular species alive are tropical arthropods associated with plants. Hence, the host-specificity of these species, and their diversity at different scales, are keys to understanding the assembly structure of global biodiversity. We present a comprehensive scheme in which tropical herbivore megadiversity can be partitioned into the following components: (A) more host plant species per se, (B) more arthropod species per plant species, (C) higher host specificity of herbivores, or (D) higher species turnover (beta diversity) in the tropics than in the temperate zone. We scrutinize recent studies addressing each component and identify methodological differences among them. We find substantial support for the importance of component A, more tropical host species. A meta-analysis of published results reveals intermediate to high correlations between plant and herbivore diversity, accounting for up to 60% of the variation in insect species richness. Support for other factors is mixed, with studies too scarce and approaches too uneven to allow for quantitative summaries. More research on individual components is unlikely to resolve their relative contribution to overall herbivore diversity. Instead, we call for the adoption of more coherent methods that avoid pitfalls for larger-scale comparisons, for studies assessing different components together rather than singly, and for studies that investigate herbivore beta-diversity (component D) in a more comprehensive perspective. [source] Food web complexity and chaotic population dynamicsECOLOGY LETTERS, Issue 3 2002Gregor F. Fussmann Abstract In mathematical models, very simple communities consisting of three or more species frequently display chaotic dynamics which implies that long-term predictions of the population trajectories in time are impossible. Communities in the wild tend to be more complex, but evidence for chaotic dynamics from such communities is scarce. We used supercomputing power to test the hypothesis that chaotic dynamics become less frequent in model ecosystems when their complexity increases. We determined the dynamical stability of a universe of mathematical, nonlinear food web models with varying degrees of organizational complexity. We found that the frequency of unpredictable, chaotic dynamics increases with the number of trophic levels in a food web but decreases with the degree of complexity. Our results suggest that natural food webs possess architectural properties that may intrinsically lower the likelihood of chaotic community dynamics. [source] PROMOTING INNOVATION IN THE ELECTRICITY INDUSTRYECONOMIC AFFAIRS, Issue 2 2010L. Lynne Kiesling Smart metering can bring significant benefits to electricity markets by allowing customers to reduce demand or increase supply when generation capacity is temporarily scarce. To reap the full efficiency and environmental benefits of this technology, regulators must allow price volatility and free entry into the market. The efficiency gains are enormous as both demand and supply will be affected by both temporary and longer-lasting price changes. Experiments have shown the value of this approach. [source] The Bookmark Standard-Setting Method: A Literature ReviewEDUCATIONAL MEASUREMENT: ISSUES AND PRACTICE, Issue 1 2006Ana Karantonis The Bookmark method for setting standards on educational tests is currently one of the most popular standard-setting methods. However, research to support the method is scarce. In this report, we review the published and unpublished literature on this method as well as some seminal work in the area of evaluating standard-setting studies. Our review highlights both strengths and limitations of the method. Strengths include its wide acceptance and panelist confidence in the method. Limitations include a potential bias to produce lower-than-intended standards and problems in selecting the most appropriate response probability value for ordering the items presented to panelists. It is clear that more research on this method is needed to support its wide use. Several areas for future research to better understand the validity of the Bookmark method for setting standards on educational tests are presented. [source] Drug injecting and syringe use in the HIV risk environment of Russian penitentiary institutions: qualitative studyADDICTION, Issue 12 2006Anya Sarang ABSTRACT Background Evidence highlights the prison as a high risk environment in relation to human immunodeficiency virus (HIV) and hepatitis C virus (HCV) transmsission associated with injecting drug use. Methods We undertook qualitative studies among 209 injecting drug users (IDUs) in three Russian cities: Moscow (n = 56), Volgograd (n = 83) and Barnaul in western Siberia (n = 70). Results Over three-quarters (77%) reported experience of police arrest related to their drug use, and 35% (55% of men) a history of imprisonment or detention. Findings emphasize the critical role that penitentiary institutions may play as a structural factor in the diffusion of HIV associated with drug injection in the Russian Federation. While drugs were perceived to be generally available in penitentiary institutions, sterile injection equipment was scarce and as a consequence routinely shared, including within large groups. Attempts to clean borrowed needles or syringes were inadequate, and risk reduction was severely constrained by a combination of lack of injecting equipment availability and punishment for its possession. Perceptions of relative safety were also found to be associated with assumptions of HIV negativity, resulting from a perception that all prisoners are HIV tested upon entry with those found HIV positive segregated. Conclusion This study shows an urgent need for HIV prevention interventions in the Russian penitentiary system. [source] Prediction of uptake dynamics of persistent organic pollutants by bacteria and phytoplanktonENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2002Sabino Del Vento Abstract Phytoplankton and bacteria play an important role on the biogeochemical cycles of persistent organic pollutants (POPs). However, experimental data and quantitative knowledge of the kinetics of uptake and depuration of most POPs by bacteria and phytoplankton are scarce. In the present paper, a procedure to predict the sorption kinetics to bacteria and phytoplankton is developed. The prediction method is the combination of a mechanistic model for sorption and quantitative structure,activity relationships relating bioconcentration factors and membrane permeability to the chemical physical-chemical properties. The model consists of two compartments where the first compartment is the cellular surface and the second compartment is the cell biomass or matrix. Equations for estimating uptake and depuration rate constants into the matrix and adsorption and desorption rate constants onto the surface are obtained. These expressions depend on the physical-chemical properties of the chemical, the environmental temperature, the microorganism size, and species-specific quality of organic matter. While microorganism shape has a secondary influence on uptake dynamics, microorganism size and chemical hydrophobicity arise as the key factors controlling the kinetics of POP incorporation into bacteria and plankton. Uptake, depuration, adsorption, and desorption rate constants are reported for POPs such as polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated dioxins and furans (PCDD/Fs), and POPs of emerging concern, such as polybrominated diphenyl ethers (PBDEs). Finally, implications of uptake and depuration dynamics on the biogeochemical cycling of POPs are discussed. [source] Assessing the impacts of grazing levels on bird density in woodland habitat: a Bayesian approach using expert opinionENVIRONMETRICS, Issue 7 2005Petra M. Kuhnert Abstract Many studies on birds focus on the collection of data through an experimental design, suitable for investigation in a classical analysis of variance (ANOVA) framework. Although many findings are confirmed by one or more experts, expert information is rarely used in conjunction with the survey data to enhance the explanatory and predictive power of the model. We explore this neglected aspect of ecological modelling through a study on Australian woodland birds, focusing on the potential impact of different intensities of commercial cattle grazing on bird density in woodland habitat. We examine a number of Bayesian hierarchical random effects models, which cater for overdispersion and a high frequency of zeros in the data using WinBUGS and explore the variation between and within different grazing regimes and species. The impact and value of expert information is investigated through the inclusion of priors that reflect the experience of 20 experts in the field of bird responses to disturbance. Results indicate that expert information moderates the survey data, especially in situations where there are little or no data. When experts agreed, credible intervals for predictions were tightened considerably. When experts failed to agree, results were similar to those evaluated in the absence of expert information. Overall, we found that without expert opinion our knowledge was quite weak. The fact that the survey data is quite consistent, in general, with expert opinion shows that we do know something about birds and grazing and we could learn a lot faster if we used this approach more in ecology, where data are scarce. Copyright © 2005 John Wiley & Sons, Ltd. [source] Environmental power analysis , a new perspectiveENVIRONMETRICS, Issue 5 2001David R. Fox Abstract Power analysis and sample-size determination are related tools that have recently gained popularity in the environmental sciences. Their indiscriminate application, however, can lead to wildly misleading results. This is particularly true in environmental monitoring and assessment, where the quality and nature of data is such that the implicit assumptions underpinning power and sample-size calculations are difficult to justify. When the assumptions are reasonably met these statistical techniques provide researchers with an important capability for the allocation of scarce and expensive resources to detect putative impact or change. Conventional analyses are predicated on a general linear model and normal distribution theory with statistical tests of environmental impact couched in terms of changes in a population mean. While these are ,optimal' statistical tests (uniformly most powerful), they nevertheless pose considerable practical difficulties for the researcher. Compounding this difficulty is the subsequent analysis of the data and the impost of a decision framework that commences with an assumption of ,no effect'. This assumption is only discarded when the sample data indicate demonstrable evidence to the contrary. The alternative (,green') view is that any anthropogenic activity has an impact on the environment and therefore a more realistic initial position is to assume that the environment is already impacted. In this article we examine these issues and provide a re-formulation of conventional mean-based hypotheses in terms of population percentiles. Prior information or belief concerning the probability of exceeding a criterion is incorporated into the power analysis using a Bayesian approach. Finally, a new statistic is introduced which attempts to balance the overall power regardless of the decision framework adopted. Copyright © 2001 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||||||||||||||||||||