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Poses Challenges (pose + challenge)
Selected AbstractsHost shifting by Operophtera brumata into novel environments leads to population differentiation in life-history traitsECOLOGICAL ENTOMOLOGY, Issue 5 2003Adam J. Vanbergen Abstract., 1. Operophtera brumata L. (Lepidoptera: Geometridae), a polyphagous herbivore usually associated with deciduous trees such as oak Quercus robur L., has expanded its host range to include the evergreen species heather Calluna vulgaris (L.) Hull and, most recently, Sitka spruce Picea sitchensis (Bong.) Carrière. 2. Phenology, morphology, and survival of O. brumata were measured at several life-history stages in populations from the three different host plant communities sampled from a range of geographical locations. The data were used to test for population differences, reflecting the marked differences in host-plant secondary chemistry, growth form, and site factors such as climate. The hypothesis that spruce-feeding populations originated from populations feeding on moorland, commonly sites of coniferous afforestation, was also tested. 3. Altitude, not host plant species, was the major influence on the timing of adult emergence. An effect of insect population independent of altitude was found, implying that additional unidentified factors contribute to this phenological variation. Larval survival and adult size varied between populations reared on different host plant species. Survival of larvae was affected negatively when reared on the novel host plant, Sitka spruce, versus the natal plant (oak or heather) but oak and heather-sourced insects did not differ in survivorship on Sitka spruce. 4. Host range extension into novel environments has resulted in population differentiation to the local climate, demonstrating that host shifts pose challenges to the herbivore population greater than those offered by the host plant alone. The hypothesis that Sitka spruce feeding populations have arisen predominantly from moorland feeding populations was not supported. [source] Controls on Ground Water Chemistry in the Central Couloir Sud Rifain, MoroccoGROUND WATER, Issue 2 2010Lahcen Benaabidate Irrigation, urbanization, and drought pose challenges for the sustainable use of ground water in the central Couloir sud rifain, a major agricultural region in north-central Morocco, which includes the cities of Fès and Meknès. The central Couloir is underlain by unconfined and confined carbonate aquifers that have suffered declines in hydraulic head and reductions in spring flow in recent decades. Previous studies have surveyed ground water flow and water quality in wells and springs but have not comprehensively addressed the chemistry of the regional aquifer system. Using graphical techniques and saturation index calculations, we infer that major ion chemistry is controlled (1) in the surficial aquifer by cation exchange, calcite dissolution, mixing with deep ground water, and possibly calcite precipitation and (2) in the confined aquifer and warm springs by calcite dissolution, dolomite dissolution, mixing with water that has dissolved gypsum and halite, and calcite precipitation. Analyses of 2H and 18O indicate that shallow ground water is affected by evaporation during recharge (either of infiltrating precipitation or return flow), whereas deep ground water is sustained by meteoric recharge with little evaporation. Mechanisms of recharge and hydrochemical evolution are broadly consistent with those delineated for similar regional aquifer systems elsewhere in Morocco and in southern Spain. [source] Passenger route guidance system for multi-modal transit networksJOURNAL OF ADVANCED TRANSPORTATION, Issue 3 2005Hong K. Lo In many public transport oriented cities in the world, especially Asian cities, the public transport system has been developed extensively, to the extent that it has become increasingly difficult to navigate. Although inter-modal transfers are common and often necessary, a complete set of the routes across transport modes is generally not presented in a form that is accessible to travelers, as each operator would only publish its own routes. Moreover, the common nonlinear fare tables together with inter-modal fare discounts pose challenges to travelers in deciding their best routes. This study develops a multi-modal passenger route guidance system, called eFinder, to aid travelers with their combined mode-route choices. We discuss the architecture and features of this system in this study. This system forms a platform for disseminating public transit information and should complement further development and use of the public transport network by enabling travelers to make informed choices. [source] Introduction to "Ethnographic Emergences"AMERICAN ANTHROPOLOGIST, Issue 1 2005BILL MAURER This introduction situates the articles in this "In Focus" in terms of the history of anthropological theory. I argue that the objects under ethnographic scrutiny here compel a rethinking of ethnography as a method and a retooling of the theoretical apparatus of the discipline. Such fields as medicine, science, media, law, and environment pose challenges to modernist analytical toolkits because they are always already complex hybrids of nature and culture. They do not stay put inside their own analytical frames. They are also autodocumentary and make use of the shift in perspective between general and particular to generate knowledge,much as anthropology does. This introduction is an argument for an anthropology of emergence that is not content to settle for mere descriptive adequacy but that uses its objects to unsettle anthropological claims to knowledge. [source] Constructing a ,plausible narrative of progress' for nursing: a neopragmatist suggestionNURSING PHILOSOPHY, Issue 1 2009Walter H. Mason MSN RN PMHCNS-BC CNL Abstract Identity, difference, and the associated subject of cultural diversity pose challenges for nursing. As the demographics of the world change, demands are rising for nurses to provide sensitive, individualized care to people living in our ever-changing global community. Issues concerning gender, sexuality, disability, age, language, economic and occupational status, multiculturalism, and ethnicity are made more complex because many of these topics strike a personal chord for individual nurses. In order for nursing to provide appropriate care to the world's people and to meet future challenges, nursing must define itself in new ways. Kikuchi and Simmons have stated that the best way for nursing to approach this task is through the development of a ,sound' philosophy of nursing that will ,accommodate diversity in nursing thought'. They contend that before we can establish a philosophy of nursing, nurses will have to agree upon the nature of reality, human beings, truth, and knowledge. This paper will suggest that neopragmatism, as described by Richard Rorty, is a way to assure diversity of thought in nursing. However, I will argue against the requirement for this philosophy to be ,sound' in the sense that Kikuchi and Simmons use this term. In place of their call for ,truth and unity in nursing thought'. I will attempt to demonstrate how neopragmatic ideas relate to the construction of what Rorty called a unifying ,plausible narrative of progress'. This change will allow nursing to abandon the dead end debate over epistemologies and instead focus on more important issues related to improving nursing practice. [source] Disrupting the Master Narrative: Global Politics, Historical Memory, and the Implications for Naturalization EducationANTHROPOLOGY & EDUCATION QUARTERLY, Issue 1 2010Daryl M. Gordon Dramatic increases in immigration pose challenges for democratic citizenship education to involve national members with different historical memories and current experiences of national belonging. The article draws on ethnographic research with Laotian refugees, who were the target of U.S. violence during the Vietnam War and later became naturalized U.S. citizens. The author contrasts the narrative of citizenship that informs naturalization education with complex ideologies of citizenship articulated by refugees. She argues that a nuanced understanding of citizenship can lead to more meaningful naturalization education, which is necessary to produce citizens with a full sense of national membership and agency in the democratic process.,[naturalization, national belonging, citizenship education, refugees] [source] RESTRUCTURING U.S. FEDERAL FINANCIAL REGULATIONCONTEMPORARY ECONOMIC POLICY, Issue 3 2007ROSE M. KUSHMEIDER Despite changes over the past 70 yr, the U.S. federal financial regulatory system remains rooted in the reforms of the 1930s. The institutions governed by this system have, nevertheless, continued to evolve. Today, regulation of large, multiproduct, internationally active financial organizations poses challenges for a system designed largely to regulate smaller, distinct, locally based organizations. Reform of the regulatory system, however, is not an easy task,complex issues regarding deposit insurance, the role of the central bank, and the dual banking system must be addressed. In the absence of a crisis, however, regulatory restructuring will not likely generate much political interest. (JEL G28) [source] Finding starting points for Markov chain Monte Carlo analysis of genetic data from large and complex pedigreesGENETIC EPIDEMIOLOGY, Issue 1 2003Yuqun Luo Abstract Genetic data from founder populations are advantageous for studies of complex traits that are often plagued by the problem of genetic heterogeneity. However, the desire to analyze large and complex pedigrees that often arise from such populations, coupled with the need to handle many linked and highly polymorphic loci simultaneously, poses challenges to current standard approaches. A viable alternative to solving such problems is via Markov chain Monte Carlo (MCMC) procedures, where a Markov chain, defined on the state space of a latent variable (e.g., genotypic configuration or inheritance vector), is constructed. However, finding starting points for the Markov chains is a difficult problem when the pedigree is not single-locus peelable; methods proposed in the literature have not yielded completely satisfactory solutions. We propose a generalization of the heated Gibbs sampler with relaxed penetrances (HGRP) of Lin et al., ([1993] IMA J. Math. Appl. Med. Biol. 10:1,17) to search for starting points. HGRP guarantees that a starting point will be found if there is no error in the data, but the chain usually needs to be run for a long time if the pedigree is extremely large and complex. By introducing a forcing step, the current algorithm substantially reduces the state space, and hence effectively speeds up the process of finding a starting point. Our algorithm also has a built-in preprocessing procedure for Mendelian error detection. The algorithm has been applied to both simulated and real data on two large and complex Hutterite pedigrees under many settings, and good results are obtained. The algorithm has been implemented in a user-friendly package called START. Genet Epidemiol 25:14,24, 2003. © 2003 Wiley-Liss, Inc. [source] A Stable and Efficient Numerical Algorithm for Unconfined Aquifer AnalysisGROUND WATER, Issue 4 2009Elizabeth Keating The nonlinearity of equations governing flow in unconfined aquifers poses challenges for numerical models, particularly in field-scale applications. Existing methods are often unstable, do not converge, or require extremely fine grids and small time steps. Standard modeling procedures such as automated model calibration and Monte Carlo uncertainty analysis typically require thousands of model runs. Stable and efficient model performance is essential to these analyses. We propose a new method that offers improvements in stability and efficiency and is relatively tolerant of coarse grids. It applies a strategy similar to that in the MODFLOW code to the solution of Richard's equation with a grid-dependent pressure/saturation relationship. The method imposes a contrast between horizontal and vertical permeability in gridblocks containing the water table, does not require "dry" cells to convert to inactive cells, and allows recharge to flow through relatively dry cells to the water table. We establish the accuracy of the method by comparison to an analytical solution for radial flow to a well in an unconfined aquifer with delayed yield. Using a suite of test problems, we demonstrate the efficiencies gained in speed and accuracy over two-phase simulations, and improved stability when compared to MODFLOW. The advantages for applications to transient unconfined aquifer analysis are clearly demonstrated by our examples. We also demonstrate applicability to mixed vadose zone/saturated zone applications, including transport, and find that the method shows great promise for these types of problem as well. [source] Tracheostomy management in Acute Care Facilities , a matter of teamworkJOURNAL OF CLINICAL NURSING, Issue 9-10 2010Vicki Parker Aim., Implement and evaluate an inter-disciplinary team approach to tracheostomy management in non-critical care. Background., Trends towards early tracheostomy in intensive care units (ICU) have led to increased numbers of tracheostomy patients. Together with the push for earlier discharge from ICU, this poses challenges across disciplines and wards. Even though tracheostomy is performed across a range of patient groups, tracheostomy care is seen as the domain of specialist clinicians in critical care. It is crucial to ensure quality care regardless of the patient's destination after ICU. Design., A mixed method evaluation incorporating quantitative and qualitative approaches. Method., Data collection included pre-implementation and postimplementation clinical audits and staff surveys and a postimplementation tracheostomy team focus group. Descriptive and inferential analysis was used to identify changes in clinical indicators and staff experiences. Focus group data were analysed using iterative processes of thematic analysis. Results., Findings revealed significant reductions in mean hospital length of stay (LOS) for survivors from 50,27 days (p < 0·0001) and an increase in the number of tracheostomy patients transferred to non-critical care wards in the postgroup (p = 0·006). The number of wards accepting patients from ICU increased from 3,7 and there was increased staff knowledge, confidence and awareness of the team's role. Conclusion., The team approach has led to work practice and patient outcome improvements. Organisational acceptance of the team has led to more wards indicating willingness to accept tracheostomy patients. Improved communication has resulted in more timely referral and better patient outcomes. Relevance to clinical practice., This study highlights the importance of inter-disciplinary teamwork in achieving effective patient outcomes and efficiencies. It offers a model of inter-disciplinary practice, supported by communication and data management that can be replicated across other patient groups. [source] Relationships between perceived features and similarity of images: A test of Tversky's contrast modelJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 10 2007Abebe Rorissa The rapid growth of the numbers of images and their users as a result of the reduction in cost and increase in efficiency of the creation, storage, manipulation, and transmission of images poses challenges to those who organize and provide access to images. One of these challenges is similarity matching, a key component of current content-based image retrieval systems. Similarity matching often is implemented through similarity measures based on geometric models of similarity whose metric axioms are not satisfied by human similarity judgment data. This study is significant in that it is among the first known to test Tversky's contrast model, which equates the degree of similarity of two stimuli to a linear combination of their common and distinctive features, in the context of image representation and retrieval. Data were collected from 150 participants who performed an image description and a similarity judgment task. Structural equation modeling, correlation, and regression analyses confirmed the relationships between perceived features and similarity of objects hypothesized by Tversky. The results hold implications for future research that will attempt to further test the contrast model and assist designers of image organization and retrieval systems by pointing toward alternative document representations and similarity measures that more closely match human similarity judgments. [source] ESTIMATING EFFECTS OF SYSTEMATIC TREATMENT ON RENAL FAILURE AND DEATH WITHOUT A PARALLEL PLACEBO CONTROL GROUPNEPHROLOGY, Issue 3 2000Hoy We Background: Chronic disease programs are poorly developed in most Aboriginal communities. Much disease is unrecognised or inadequately treated, although appropriate interventions profoundly reduce morbidity and mortality in nonAboriginal populations. Programs of improved management must aspire to best practice for all, so that maintaining parallel untreated control groups is unethical. This poses challenges for evaluating effect. Methods: We identified a large burden of chronic disease in a 1990-1995 screening program in one community, and started a renal & cardiovascular-protection program in Nov 1995. This centred around use of ACE inhibitors, rigorous BP control, better control of glycemia and lipids, & health education. By late 1999 about 275 people, or 30% of all adults had enrolled. The courses of BP, albuminuria and GFR was compared with those in the pre-program era (ANZSN, 1999). Treatment effects on renal failure & natural death were estimated in 3 ways. 1) Comparison of these endpoints in the "intention to treat" group with those in persons potentially eligible for treatment on their 1990-1995 screening results, ,controls'. There was 50% overlap between the groups, & controls were younger and had less severe disease than the treatment group. 2.Community-based trends in endpoints. 3. Comparison of these trends with those in other NT Top End communities. Results: 1. Risk ratios of rates, Kaplan Meier survivals, and Cox hazard ratios all showed better survival of the treated group over controls, with estimates of 41%-64% reductions in endpoints, after accounting for disease severity. 2. Dialysis starts in the entire community have fallen by at least 38% and natural deaths by 32%. 3. In contrast dialysis continue to increase at 11% per yr in other communities and deaths have not fallen. These results all suggest a marked benefit from the treatment program. Similar methods might be used where truly controlled observations are not feasible. [source] ESTIMATING EFFECTS OF SYSTEMATIC TREATMENT ON RENAL FAILURE AND DEATH WITHOUT A PARALLEL PLACEBO CONTROL GROUPNEPHROLOGY, Issue 3 2000Hoy We Background: Chronic disease programs are poorly developed in most Aboriginal communities. Much disease is unrecognised or inadequately treated, although appropriate interventions profoundly reduce morbidity and mortality in nonAboriginal populations. Programs of improved management must aspire to best practice for all, so that maintaining parallel untreated control groups is unethical. This poses challenges for evaluating effect. Methods: We identified a large burden of chronic disease in a 1990-1995 screening program in one community, and started a renal & cardiovascular-protection program in Nov 1995. This centred around use of ACE inhibitors, rigorous BP control, better control of glycemia and lipids, & health education. By late 1999 about 275 people, or 30% of all adults had enrolled. The courses of BP, albuminuria and GFR was compared with those in the pre-program era (ANZSN, 1999). Treatment effects on renal failure & natural death were estimated in 3 ways. 1) Comparison of these endpoints in the "intention to treat" group with those in persons potentially eligible for treatment on their 1990-1995 screening results, ,controls'. There was 50% overlap between the groups, & controls were younger and had less severe disease than the treatment group. 2.Community-based trends in endpoints. 3. Comparison of these trends with those in other NT Top End communities. Results: 1. Risk ratios of rates, Kaplan Meier survivals, and Cox hazard ratios all showed better survival of the treated group over controls, with estimates of 41%-64% reductions in endpoints, after accounting for disease severity. 2. Dialysis starts in the entire community have fallen by at least 38% and natural deaths by 32%. 3. In contrast dialysis continue to increase at 11% per yr in other communities and deaths have not fallen. These results all suggest a marked benefit from the treatment program. Similar methods might be used where truly controlled observations are not feasible. [source] Regional and local labour market prospects: the importance of ageing in workforce developmentPOPULATION, SPACE AND PLACE (PREVIOUSLY:-INT JOURNAL OF POPULATION GEOGRAPHY), Issue 5 2006Anne Green Abstract Overall, the labour force in the UK is ageing, although at different rates in different areas. This poses challenges for workforce development, and has implications not only for older workers, but for everyone, everywhere. However, demography is only one element in labour supply. It needs to be considered alongside trends in participation rates and in a broader policy and cultural context, and alongside likely changes in labour demand, in order to gain a picture of regional and local labour market prospects. The thrust of government policy is to raise employment rates amongst older people (aged 50,69) and to promote ,active ageing'. The decline in employment rates amongst older men evident in the 1980s has been reversed, but participation rates remain low by earlier standards. Shifts in the industrial and occupational structure of employment mean that there is likely to be a growing demand for customer care and service skills, which older people are well-placed to provide. Yet estimates of ,replacement demand' show that some of the most pressing workforce development issues are experienced in declining sectors and occupations, with an older than average age profile. Examples include agriculture and social care in Cornwall, where there is a lack of new recruits to replace those retiring. It is concluded that improved local intelligence on labour market flows and prospects is needed to inform skills and learning priorities. Copyright © 2006 John Wiley & Sons, Ltd. [source] Intracellular metabolite determination in the presence of extracellular abundance: Application to the penicillin biosynthesis pathway in Penicillium chrysogenum,BIOTECHNOLOGY & BIOENGINEERING, Issue 1 2010Rutger D. Douma Abstract Important steps in metabolic pathways are formed by the transport of substrates and products over the cell membrane. The study of in vivo transport kinetics requires accurate quantification of intra- and extracellular levels of the transported compounds. Especially in case of extracellular abundance, the proper determination of intracellular metabolite levels poses challenges. Efficient removal of extracellular substrates and products is therefore important not to overestimate the intracellular amounts. In this study we evaluated two different rapid sampling methods, one combined with cold filtration and the other with centrifugation, for their applicability to determine intracellular amounts of metabolites which are present in high concentrations in the extracellular medium. The filtration-based method combines fast sampling and immediate quenching of cellular metabolism in cold methanol, with rapid and effective removal of all compounds present outside the cells by means of direct filtration and subsequent filtration-based washing. In the centrifugation-based method, removal of the extracellular metabolites from the cells was achieved by means of multiple centrifugation and resuspension steps with the cold quenching solution. The cold filtration method was found to be highly superior to the centrifugation method to determine intracellular amounts of metabolites related to penicillin-G biosynthesis and allowed the quantification of compounds of which the extracellular amounts were 3,4 orders of magnitude higher than the intracellular amounts. Using this method for the first time allowed to measure the intracellular levels of the side chain precursor phenylacetic acid (PAA) and the product penicillin-G of the penicillin biosynthesis pathway, compounds of which the transport mechanism in Penicillium chrysogenum is still far from being sufficiently understood. Biotechnol. Bioeng. 2010;107: 105,115. © 2010 Wiley Periodicals, Inc. [source] The National Bowel Cancer Audit: the risks and benefits of moving to open reporting of clinical outcomesCOLORECTAL DISEASE, Issue 8 2010M. R. Thompson Abstract Background, The government's proposals to openly report clinical outcomes poses challenges to the National Bowel Cancer Audit now funded by the UK department of health. Aim, To identify the benefits and risks of open reporting and to propose ways the risks might be minimized. Methods, A review of the literature on clinical audit and the consequences of open reporting. Results, There are significant potential benefits of a national audit of bowel cancer including protecting patients from sub-standard care, providing clinicians with externally validated evidence of their performance, outcome data for clinical governance and evidence that increases in government expenditure are achieving improvements in survival from bowel cancer. These benefits will only be achieved if the audit captures most of the cases of bowel cancer in the UK, the data collected is complete and accurate, the results are risk adjusted and these are presented to the public in a way that is fair, clear and understandable. Involvement of clinicians who have confidence in the results of the audit and who actively compare their own results against a national standard is essential. It is suggested that a staged move to open reporting should minimise the risk of falsely identifying an outlying unit. Conclusion, The fundamental aim of the National Bowel Cancer Audit is the pursuit of excellence by identification and adoption of best practice. This could achieve a continuous improvement in the care of all patients with bowel cancer in the UK. The ACPGBI suggests a safer way of transition to open reporting to avoid at least some of its pitfalls. [source] | |||||||||||||||||||