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Selected AbstractsComparing Frequent and Average Users of Elementary School-Based Health Centers in the Bronx, New York CityJOURNAL OF SCHOOL HEALTH, Issue 4 2002Raymundo S. Baquiran ABSTRACT: This study analyzed health care utilization at three school-based health centers (SBHCs) in the Bronx, New York City, and compared characteristics of "frequent" and "average" service users. Encounter form data for visits by 2,795 students who received services at least once between September 7, 1998, and June 30, 1999, were reviewed. Demographic comparisons between clinic users and the total school population, and between "frequent" (five or more visits/year) and "average" (one to four visits/year) users were made. The two groups also were compared after primary diagnoses were classified into five general categories. Some 96% (3,469/3,614) of students were registered in the SBHCs, of whom 81% (2,795/3,469) used clinic services at least once during the school year. Clinic users did not differ from the general school population by gender, but were younger (p < 0.01). "Frequent" users were more likely than "average" users to be older (p < 0.01), but they did not differ by gender, race/ethnicity, or insurance status. "Frequent" users comprised 28% of the clinic-using population, but accounted for 72.5% of all visits. Similarly, "average" users comprised 72.4% of the clinic-using population, but accounted for 27.5% of all visits. "Frequent" users generated most visits for mental health and chronic medical conditions, while "average" users generated most visits for preventive care, acute medical care, and injuries/emergencies (p < 0.01 for all). Important challenges for elementary SBHCs include developing new approaches that meet children's needs while protecting clinic resources, like scheduling group interventions for those with on-going health care needs who require frequent use of school health services. [source] Studying natural structural protein fibers by solid-state nuclear magnetic resonanceCONCEPTS IN MAGNETIC RESONANCE, Issue 1 2009Alexandre A. Arnold Abstract As a consequence of evolutionary pressure, various organisms have developed structural fibers displaying a range of exceptional mechanical properties adapted specifically to their functions. An understanding of these properties at the molecular level requires a detailed description of local structure, orientation with respect to the fiber and size of constitutive units, and dynamics on various timescales. The size and lack of long-range order in these protein systems constitute an important challenge to classical structural techniques such as high-resolution NMR and X-ray diffraction. Solid-state NMR overcomes these constraints and is uniquely suited to the study of these inherently disordered systems. Solid-state NMR experiments developed or applied to determine structure, orientation, and dynamics of these complex proteins will be reviewed and illustrated through examples of their applications to fibers such as spider and silkworm silks, collagen, elastin, and keratin. © 2009 Wiley Periodicals, Inc. Concepts Magn Reson Part A 34A: 24,27, 2009. [source] Early detection and intervention in first-episode schizophrenia: a critical reviewACTA PSYCHIATRICA SCANDINAVICA, Issue 5 2001T. K. Larsen Objective: To review the literature on early intervention in psychosis and to evaluate relevant studies. Method: Early intervention was defined as intervention in the prodromal phase (primary prevention) and intervention after the onset of psychosis, i.e. shortening of duration of untreated psychosis (DUP) (secondary prevention). Results: We found few studies aimed at early intervention, but many papers discussing the idea at a more general level. We identified no studies that prove that intervention in the prodromal phase is possible without a high risk for treating false positives. We identified some studies aimed at reducing DUP, but the results are ambiguous and, until now, no follow-up data showing a positive effect on prognosis have been presented. Conclusion: Early intervention in psychosis is a difficult and important challenge for the psychiatric health services. At the time being reduction of DUP seems to be the most promising strategy. Intervention in the prodromal phase is more ethically and conceptually problematic. [source] Symbolic dynamics for identifying similarity between rhythms of ecological time seriesECOLOGY LETTERS, Issue 9 2004Bernard Cazelles Abstract Explaining the associations between animal populations or between population and environmental signals is an important challenge. The time series that quantify animal populations are often complex, nonlinear, noisy and non-stationary. These characteristics may make it inappropriate to use traditional techniques when analysing these time series and their mutual dependencies. Here I propose to use symbolic dynamics and techniques from Information Theory to evaluate the degree of dynamic cohesion between time series fluctuations. The main idea is to check whether two (or more) signals tend to oscillate simultaneously, rising and falling together with the same rhythm. Based on synthetic and real time series, I demonstrate that this method is robust to the presence of noise and to the short length of the analysed time series and gives relevant information about the weak relationships between different series. Furthermore, this method appears as simple as classical cross-correlation and outperforms it in the analysed examples. [source] The emerging role of neuronal nitric oxide synthase in the regulation of myocardial functionEXPERIMENTAL PHYSIOLOGY, Issue 6 2006Barbara Casadei The recent discovery of a NOS1 gene product (i.e. a neuronal-like isoform of nitric oxide synthase or nNOS) in the mammalian left ventricular (LV) myocardium has provided a new key for the interpretation of the complex experimental evidence supporting a role for myocardial constitutive nitric oxide (NO) production in the regulation of basal and ,-badrenergic cardiac function. Importantly, nNOS gene deletion has been associated with more severe LV remodelling and functional deterioration in murine models of myocardial infarction, suggesting that nNOS-derived NO may also be involved in the myocardial response to injury. To date, the mechanisms by which nNOS influences myocardial pathophysiology remain incompletely understood. In particular, it seems over simplistic to assume that all aspects of the myocardial phenotype of nNOS knockout (nNOS,/,) mice are a direct consequence of lack of NO production from this source. Emerging data showing co-localisation of xanthine oxidoreductase (XOR) and nNOS in the sarcoplasmic reticulum of rodents, and increased XOR activity in the nNOS,/, myocardium, suggest that nNOS gene deletion may have wider implications on the myocardial redox state. Similarly, the mechanisms regulating the targeting of myocardial nNOS to different subcellular compartments and the functional consequences of intracellular nNOS trafficking have not been fully established. Whether this information could be translated into a better understanding and management of human heart failure remains the most important challenge for future investigations. [source] Acceptable prior fatigue damage and failure threshold for impact loading of an aluminium alloyFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 1 2001T. Auzanneau In a competitive economic context that aims at gains in safety, some problems of combined fatigue-impact loadings are crucial, particularly in the case of light alloys used in the transport and aeronautical industries. One important challenge is to quantify the fatigue preloading effect on the residual dynamic plasticity of a 2017-A T3 aluminium alloy. From an experimental modal analysis, the change in mechanical properties of prefatigued material under impact loading allows us to define the best mechanical parameter for a limiting threshold between a no-damage state and weakened states due to fatigue predamage. For this situation a hybrid technique has been developed. A numerical model including voids (which represent surface micro-cracks produced by the fatigue preloading) is fitted to the results obtained by the modal analysis of the damaged sample. Hence, an acceptable damage threshold (i.e. a damage critical volume below which the impact toughness is not affected by fatigue preloading) and a failure threshold are established. On the basis of this methodology, it is possible to predict the energy required for the impact failure of prefatigued specimens and therefore to predict a safe or a dangerous mechanical state. [source] Rational Pricing of Internet Companies RevisitedFINANCIAL REVIEW, Issue 4 2001Eduardo S. Schwartz G12 Abstract In this article we expand and improve the Internet company valuation model of Schwartz and Moon (2000) in numerous ways. By using techniques from real options theory and modern capital budgeting, the earlier paper demonstrated that uncertainty about key variables plays a major role in the valuation of high growth Internet companies. Presently, we make the model more realistic by providing for stochastic costs and future financing, and also by including capital expenditures and depreciation in the analysis. Perhaps more importantly, we offer insights into the practical implementation the model. An important challenge to implementing the original model was estimating the various parameters of the model. Here, we improve the procedure by setting the speed of adjustment parameters equal to one another, by tying the implied half-life of the revenue growth process to analyst forecasts, and by inferring the risk-adjustment parameter from the observed beta of the company's stock price. We illustrate these extensions in a valuation of the company eBay. [source] Finnish lake fisheries and conservation of biodiversity: coexistence or conflict?FISHERIES MANAGEMENT & ECOLOGY, Issue 1-2 2000P. Salmi The conservation of biodiversity in aquatic habitats has become an increasingly important challenge in the management of water resources. In addition to the complexity of the lake fishery and the management structure, the popularity of gill net fishing, in particular, has brought problems when re-establishing populations of Arctic charr, Salvelinus alpinus (L.), collecting genetically sustainable numbers of spawners of the land-locked salmon, Salmo salar m. sebago (Girard), and increasing the population of the Saimaa ringed seal, Phoca hispida saimensis (Nordq.) to a sustainable level in the Vuoksi watercourse, south-east Finland. The attitudes towards protection among the users and other interested parties vary. In order to enhance the coexistence of the lake fishery and endangered species over large water areas, improved institutional linkages are needed among the local, regional and governmental levels of the fragmented decision-making regime. Environmental interests should also be integrated into the communication structure. [source] Control of the Morphology and Structural Development of Solution-Processed Functionalized Acenes for High-Performance Organic TransistorsADVANCED FUNCTIONAL MATERIALS, Issue 10 2009Jung Ah Lim Abstract Solution-processable functionalized acenes have received special attention as promising organic semiconductors in recent years because of their superior intermolecular interactions and solution-processability, and provide useful benchmarks for organic field-effect transistors (OFETs). Charge-carrier transport in organic semiconductor thin films is governed by their morphologies and molecular orientation, so self-assembly of these functionalized acenes during solution processing is an important challenge. This article discusses the charge-carrier transport characteristics of solution-processed functionalized acene transistors and, in particular, focuses on the fine control of the films' morphologies and structural evolution during film-deposition processes such as inkjet printing and post-deposition annealing. We discuss strategies for controlling morphologies and crystalline microstructure of soluble acenes with a view to fabricating high-performance OFETs. [source] Health care reform in BelgiumHEALTH ECONOMICS, Issue S1 2005Erik Schokkaert Abstract Curbing the growth of public sector health expenditures has been the proclaimed government objective in Belgium since the 1980s. However, the respect for freedom of choice for patients and for therapeutic freedom for providers has blocked the introduction of microeconomic incentives and quality control. Therefore , with some exceptions, particularly in the hospital sector , policy has consisted mainly of tariff and supply restrictions and increases in co-payments. These measures have not been successful in curbing the growth of expenditures. Moreover, there remains a large variation in medical practices. While the structure of health financing is relatively progressive from an international perspective, socioeconomic and regional inequalities in health persist. The most important challenge is the restructuring of the basic decision-making processes; i.e. a simplification of the bureaucratic procedures and a re-examination of the role of regional authorities and sickness funds. Copyright © 2002 John Wiley & Sons, Ltd. [source] Determinants of perceived health in families of patients with heart diseaseJOURNAL OF ADVANCED NURSING, Issue 2 2004Päivi Ĺstedt-Kurki PhD RN Background., Heart disease is a severe long-term illness, which often requires lifestyle changes and self-care and affects the life of the whole family. Perceived family health is highly complex. It combines people's values and everyday experiences, such as knowledge about their own health, what they do to promote their health, how their life progresses, and how they feel physically and emotionally. Aim., The aim of this paper is to report a study to describe the perceived health of families of patients with heart disease and to ascertain factors related to family health. Methods., Data were collected by questionnaire with a convenience sample of 161 family members of patients receiving treatment on two medical wards of a university hospital in southern Finland. Data were analysed using means and medians and tested by parametric and non-parametric tests. A stepwise regression analysis was also used. Results., The most important predictors of family health were family structural factors, effect of illness symptoms on daily life, and family relationships. The strongest predictor was family structural factors. It was found that the better the family structure and relationships, the better the family health. Similarly, the greater the effect of the illness on the patient's daily life, the worse the family health. Conclusion., The findings suggest that supporting family functioning in the families of people with heart disease is an important challenge for family nursing. [source] Performance of a new furnace for high-resolution synchrotron powder diffraction up to 1900,K: application to determine electron density distribution of the cubic CaTiO3 perovskite at 1674,KJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 5 2004Masatomo Yashima Accurate crystal structure analysis at high temperatures is an important challenge in science and technology. A new electric furnace for the measurement of high-resolution (,d/d = 0.03%) synchrotron radiation powder diffraction profiles from materials at high temperatures (up to 1900,K in air) has been designed and fabricated. This furnace consists of a ceramic refractory with MoSi2 heaters, an aluminium body cooled by flowing water, and a sample stage with a spinner and a controller for sample-height adjustment. In situ synchrotron powder diffraction measurement for a calcium titanate perovskite specimen at 1674,K has been performed using the furnace at beamline 3A of the Photon Factory. The electron density distribution of the cubic perovskite at 1674,K was successfully obtained using a combination of Rietveld refinement, the maximum-entropy method (MEM) and MEM-based pattern-fitting techniques. The Ti atoms exhibit covalent bonding with the O atoms in the cubic CaTiO3 perovskite at this temperature, while the Ca atoms are ionic. These results indicate that the new furnace yields high-quality data for accurate crystal structure analysis. [source] How issues get framed and reframed when different communities meet: a multi-level analysis of a collaborative soil conservation initiative in the Ecuadorian AndesJOURNAL OF COMMUNITY & APPLIED SOCIAL PSYCHOLOGY, Issue 3 2004Art Dewulf Abstract Drawing on qualitative data from a longitudinal case study of a collaborative soil conservation initiative in southern Ecuador, we study how multiple actors, including university experts, development organizations and local communities, make sense of the issues from different perspectives through the process of issue framing. Starting from an analysis of the actors' usual issue frames, we point out their differences in selecting aspects, connecting them and drawing boundaries around the issues. Bringing in the time dimension leads us to consider how changing patterns of actor involvement and evolving frame configurations mutually influence each other. In a third step, we zoom in on the here-and-now level of ongoing interaction using discourse analysis, outlining an interactive, communicative and discursive approach to dealing with differences in issue framing. We identify various ways of dealing with these differences and argue that approaching them constructively by tuning the different frames into a mutually acceptable configuration is an important challenge for any attempt at integrated management of natural resources. Copyright © 2004 John Wiley & Sons, Ltd. [source] Up-regulation of heat shock protein HSP 20 in the hippocampus as an early response to hypoxia of the newbornJOURNAL OF NEUROCHEMISTRY, Issue 2 2006Jean-Claude David Abstract Hypoxia is an important challenge for newborn mammals. Stress generated at the brain level under low oxygenation conditions results in up-regulation of heat shock proteins (HSPs) and other stress proteins. The aim of the present work was to determine the effect of hypoxia in the newborn on some newly described small molecular weight HSPs (HSP 20 and B8) in the hippocampus, cortex and cerebellum of newborn piglets. These effects will be compared with those of other closely related proteins such as ,B crystallin, HSP 27, heme oxygenase (HO)-1, HO-2, cyclooxygenase (COX)-1 and COX-2. The piglets were submitted to hypoxia (5% O2; 95% N2) over either 1 or 4 h, with recovery periods ranging from 0 to 68 h. Western blot analysis showed that HSP 20 was rapidly induced only in the hippocampus, long before hypoxia-inducible transcription factor HIF-1,, while HSP 27 was rapidly induced in the cortex and cerebellum. Vascular epithelial growth factor was increased simultaneously in the three regions. Moreover, an increase in the expression of, respectively, HO-1 and COX-2 was observed later, but at the same time, in the three regions tested. It appears that HSP 20 can be an early marker of hypoxia in the hippocampus. The other small HSPs or stress proteins display different temporal patterns of up-regulation (HSP 27 and HO-1, COX-2) or do not show changes in their expressions (,B crystallin, HSP B8, HO-2 and COX-1). [source] An outcomes research perspective on medical education: the predominance of trainee assessment and satisfactionMEDICAL EDUCATION, Issue 4 2001Jay B Prystowsky Context A fundamental premise of medical education is that faculty should educate trainees, that is, students and residents, to provide high quality patient care. Yet, there is little research on the effect of medical education on patient outcomes. Objective A content analysis of leading medical education journals was performed to determine the primary foci of medical education research, using a three- dimensional outcomes research framework based on the paradigm of health services outcomes research. Data sources All articles in three medical education journals (Academic Medicine, Medical Education, and Teaching and Learning in Medicine) from 1996 to 1998 were reviewed. Papers presented at the Research in Medical Education conference at the Association of American Medical Colleges annual meeting during the same period, and published as Academic Medicine supplements, were also analysed. Study selection Only data-driven articles were selected for analysis; thus editorials and abstracts were excluded. Data extraction Each article was categorized according to primary participant (i.e. trainee, faculty, provider and patient), outcome (performance, satisfaction, professionalism and cost), and level of analysis (geographic, system, institution and individual(s)). Data synthesis A total of 599 articles were analysed. Trainees were the most frequent participants studied (68·9%), followed by faculty (19·4%), providers (8·1%) and patients (3·5%). Performance was the most common outcome measured (49·4%), followed by satisfaction (34·1%). Cost was the focus of only 2·3% of articles and patient outcomes accounted for only 0·7% of articles. Conclusions Medical education research is dominated by assessment of trainee performance followed by trainee satisfaction. Leading journals in medical education contain little information concerning the cost and products of medical education, that is, provider performance and patient outcomes. The study of these medical education outcomes represents an important challenge to medical education researchers. [source] Can punishment maintain sex?OIKOS, Issue 2 2008Daniel J. Rankin Individuals who reproduce asexually have a two-fold advantage over their sexually-reproducing counterparts as they are able to reproduce twice as fast. Explaining why sexual reproduction is favoured over asexual reproduction therefore remains an important challenge in evolutionary biology. Various mechanisms involving resistance to parasites, adaptation to novel environments and helping to purge the genome of deleterious mutations have all been proposed as potential mechanisms which could promote the evolution of sex. A recent article has suggested that spiteful males may help to reduce the two-fold advantage of asexual females. Here I discuss this idea, and further ask whether punishment of asexual females by sexual females could be one way in which sexual reproduction could be maintained in groups of animals; in light of recent research on the repression of competition, it could be possible that asexual females which reproduce faster than their sexual counterparts will be punished for using group resources. It may therefore be possible that the behaviour of sexual individuals towards asexual females could have fitness consequences which could potentially reduce the two-fold advantage they gain from reproducing parthenogenetically. [source] Production of cyanophycin, a suitable source for the biodegradable polymer polyaspartate, in transgenic plantsPLANT BIOTECHNOLOGY JOURNAL, Issue 2 2005Katrin Neumann Summary The production of biodegradable polymers in transgenic plants in order to replace petrochemical compounds is an important challenge for plant biotechnology. Polyaspartate, a biodegradable substitute for polycarboxylates, is the backbone of the cyanobacterial storage material cyanophycin. Cyanophycin, a copolymer of l -aspartic acid and l -arginine, is produced via non-ribosomal polypeptide biosynthesis by the enzyme cyanophycin synthetase. A gene from Thermosynechococcus elongatus BP-1 encoding cyanophycin synthetase has been expressed constitutively in tobacco and potato. The presence of the transgene-encoded messenger RNA (mRNA) correlated with changes in leaf morphology and decelerated growth. Such transgenic plants were found to produce up to 1.1% dry weight of a polymer with cyanophycin-like properties. Aggregated material, able to bind a specific cyanophycin antibody, was detected in the cytoplasm and the nucleus of the transgenic plants. [source] The demographic transition revisited as a global processPOPULATION, SPACE AND PLACE (PREVIOUSLY:-INT JOURNAL OF POPULATION GEOGRAPHY), Issue 1 2004David S. Reher Abstract With dramatic declines in fertility taking place throughout the world, it is increasingly important to understand the demographic transition as a global process. While this universality was a cornerstone of classic transition theories, for many decades it was largely neglected by experts because fertility in the developing world did not seem to follow the expected pattern. When comparing earlier and more recent transition experiences, important similarities and disparities can be seen. Everywhere mortality decline appears to have played a central role for fertility decline. The differences in the timing of the response of fertility to mortality decline, with very small gaps historically and prolonged ones in more recent transitions, plus the much more rapid decline in vital rates in many developing countries, constitute an important challenge to any general explanation of the process. The specific characteristics of recent transitions have led to decades of higher population growth rates, and promise to give way to much more rapid dynamics of population ageing in many countries. This may limit the ability of newcomers to take full advantage of the demographic transition for the social and economic modernisation of their societies. Copyright © 2004 John Wiley & Sons, Ltd. [source] Dihydropyrimidinase related protein-2 as a biomarker for temperature and time dependent post mortem changes in the mouse brain proteomePROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 10 2003Bo Franzén Abstract Proteome analysis in the central nervous system area represents a large and important challenge in drug discovery. One major problem is to obtain representative and well characterized tissues of high quality for analysis. We have used brain tissues from normal mice to study the effect of post mortem time (up to 32 h) and temperature (4°C and room temperature) on protein expression patterns. A number of proteins were identified using mass spectrometry and potential markers were localized. One of the proteins identified, dihydropyrimidinase related protein-2 (DRP-2), occurs as multiple spots in two-dimensional electrophoresis gels. The ratio between the truncated form of DRP-2 (fDRP-2) and full length DRP-2 is suggested as an internal control that can be used as a biomarker of post mortem time and post mortem temperature between unrelated brain protein samples. Results of this study may be useful in future efforts to detect disease specific alterations in proteomic studies of human post mortem brain tissues. [source] Beyond Cognition: Affective Leadership and Emotional LaborPUBLIC ADMINISTRATION REVIEW, Issue 1 2009Meredith A. Newman How do the concepts of emotional labor and artful affect translate into our understanding of leadership? Where would one find affective leadership in practice? To address these questions, the workdays of civil servants are examined. Based on interviews and focus groups, the authors set forth in their own words how social workers, 911 operators, corrections officials, detectives, and child guardians experience their work. These interviews reveal the centrality of emotion work in the service exchange and underscore affective leadership in practice. The authors conclude that the most important challenge facing public administrators is not to make work more efficient but to make it more humane and caring. Affective leadership, and recognition of the centrality of emotional labor therein, are the means by which this approach is championed. [source] Resilience of Native Plant Community Following Manual Control of Invasive Cinchona pubescens in GalápagosRESTORATION ECOLOGY, Issue 2010Heinke Jäger As invasive plant species are a major driver of change on oceanic islands, their control is an important challenge for restoration ecology. The post-control recovery of native vegetation is crucial for the treatments to be considered successful, but few studies have evaluated the effects of control measures on both target and non-target species. To investigate the efficiency of manual control of Cinchona pubescens and its impacts on the sub-tropical highland vegetation of Santa Cruz Island, Galápagos, vegetation was sampled before and up to two years after control was carried out in permanent sampling plots. Manual control significantly reduced Cinchona density. Due to regeneration from the seed or bud bank, follow-up control is required, however, for long-term success. Despite heavy disturbance from tree uprooting, herbaceous angiosperms were little affected by the control actions, whereas dominant fern species declined in cover initially. Most native, endemic, and other introduced species regained their pre-control levels of cover 2 years after control; some species even exceeded them. The total number of species significantly increased over the study period, as did species diversity. The native highland vegetation appeared to be resilient, recovering to a level probably more characteristic of the pre-invasion state without human intervention after Cinchona control. However, some introduced species seemed to have been facilitated by the control actions, namely Stachys agraria and Rubus niveus. Further monitoring is needed to confirm the long-term nature of vegetation change in the area. [source] Science against modernism: the relevance of the social theory of Michael PolanyiTHE BRITISH JOURNAL OF SOCIOLOGY, Issue 1 2001Charles Thorpe ABSTRACT Science, as an institution, is widely taken by sociologists to exemplify the modern tendency towards vesting trust and authority in impersonal offices and procedures, rather than in embodied human individuals. Such views of science face an important challenge in the social philosophy of Michael Polanyi. His work provides important insights into the continuing role of embodied personal authority and tradition in science and, hence, in late modernity. I explicate Polanyi's relevance for social theory, through a comparison with Weber's essay ,Science as a Vocation'. An understanding of the personal dimensions of trust and authority in science suggests practical limits to the position of Giddens on the disembedding of social relations and on the scepticism and reflexivity of modernity. [source] Developing recovery and monitoring strategies for the endemic Mount Graham red squirrels (Tamiasciurus hudsonicus grahamensis) in ArizonaANIMAL CONSERVATION, Issue 1 2004Kate E. Buenau An important challenge in conservation biology is extracting pertinent information from the available data for endangered species. Rarely do we have enough information to precisely determine an organism's risk of extinction and other factors that affect its management. How, then, can we use limited information to make responsible conservation decisions on controversial species such as the Mount Graham red squirrel? We used several analytical approaches to examine 15 years of abundance data for the Mount Graham red squirrel in order to propose recovery criteria and to evaluate alternative conservation strategies. We analysed the historical population dynamics using a diffusion approximation model and showed that the main threat to the population was not the overall growth rate (which may well be greater than 1) but rather the wide range of variation in annual growth rates. We used information on the distribution of growth rates and abundance to classify the species as threatened under the Endangered Species Act (ESA). We then presented a simple demographic model to examine the effects of proportional changes in vital rates on the population growth rate (,). The elasticity values obtained for Mount Graham red squirrels indicate that the population is far more sensitive to changes in survival rates (particularly adult survival) compared to reproduction. Our analyses suggest that management should focus on refining monitoring techniques, reducing sources of variability, improving the survival of adult animals and filling the gaps in the currently available data. [source] Computational Fluid Dynamics Analysis of Blade Tip Clearances on Hemodynamic Performance and Blood Damage in a Centrifugal Ventricular Assist DeviceARTIFICIAL ORGANS, Issue 5 2010Jingchun Wu Abstract An important challenge facing the design of turbodynamic ventricular assist devices (VADs) intended for long-term support is the optimization of the flow path geometry to maximize hydraulic performance while minimizing shear-stress-induced hemolysis and thrombosis. For unshrouded centrifugal, mixed-flow and axial-flow blood pumps, the complex flow patterns within the blade tip clearance between the lengthwise upper surface of the rotating impeller blades and the stationary pump housing have a dramatic effect on both the hydrodynamic performance and the blood damage production. Detailed computational fluid dynamics (CFD) analyses were performed in this study to investigate such flow behavior in blade tip clearance region for a centrifugal blood pump representing a scaled-up version of a prototype pediatric VAD. Nominal flow conditions were analyzed at a flow rate of 2.5 L/min and rotor speed of 3000 rpm with three blade tip clearances of 50, 100, and 200 µm. CFD simulations predicted a decrease in the averaged tip leakage flow rate and an increase in pump head and axial thrust with decreasing blade tip clearances from 200 to 50 µm. The predicted hemolysis, however, exhibited a unimodal relationship, having a minimum at 100 µm compared to 50 µm and 200 µm. Experimental data corroborate these predictions. Detailed flow patterns observed in this study revealed interesting fluid dynamic features associated with the blade tip clearances, such as the generation and dissipation of tip leakage vortex and its interaction with the primary flow in the blade-blade passages. Quantitative calculations suggested the existence of an optimal blade tip clearance by which hydraulic efficiency can be maximized and hemolysis minimized. [source] FOSTERING HOPE IN PEOPLE LIVING WITH AIDS IN AFRICA: THE ROLE OF PRIMARY HEALTH-CARE WORKERSAUSTRALIAN JOURNAL OF RURAL HEALTH, Issue 4 2001Henry Abayomi Akinsola ABSTRACT: Today the medical literature is dominated by discussions on issues related to HIV/AIDS. This is not surprising considering the fact that in the history of humankind, the HIV/AIDS scenario has posed one of the greatest challenges. The reality of the physical, socioeconomic and psychological problems associated with the AIDS epidemic has become obvious to the general populace in Africa. Currently, both the AIDS victims and several others in the society continue to entertain the fear of dying from AIDS. The situation has become a source of concern to almost everyone, including primary health-care (PHC) workers. While several options are being examined to address the AIDS problem in Africa, one area that is often neglected is how to foster hope in people living with AIDS (PLWA) and their caregivers. In an attempt to examine this issue, this paper discusses the concept of hope, the cultural construct of HIV/AIDS in African countries and the role of PHC workers in fostering hope in PLWA. The paper concludes that by assisting the PLWA to develop a good sense of hope, PHC workers will be able to meet an important challenge: how to improve the quality of life for PLWA. [source] RNA interference of sialidase improves glycoprotein sialic acid content consistencyBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2006Frederyk A. Ngantung Abstract An important challenge facing therapeutic protein production in mammalian cell culture is the cleavage of terminal sialic acids on recombinant protein glycans by the glycosidase enzymes released by lysed cells into the supernatant. This undesired phenomenon results in a protein product which is rapidly cleared from the plasma by asialoglycoprotein receptors in the liver. In this study, RNA interference was utilized as a genetic approach to silence the activity of sialidase, a glycosidase responsible for cleaving terminal sialic acids on IFN-, produced by Chinese Hamster Ovary (CHO) cells. We first identified a 21-nt double stranded siRNA that reduced endogenous sialidase mRNA and protein activity levels. Potency of each siRNA sequences was compared using real time RT-PCR and a sialidase activity assay. We next integrated the siRNA sequence into CHO cells, allowing production and selection of stable cell lines. We isolated stable clones with sialidase activity reduced by over 60% as compared to the control cell line. Micellar electrokinetic chromatography (MEKC), thiobarbituric acid assay (TAA), and high performance anion exchange chromatography (HPAEC) coupled to amperometric detection were performed to analyze glycan site occupancy, sialic acid content, and distribution of asialo-/sialylated-glycan structures, respectively. Two of the stable clones successfully retained the full sialic acid content of the recombinant IFN-,, even upon cells' death. This was comparable to the case where a chemically synthesized sialidase inhibitor was used. These results demonstrated that RNA interference of sialidase can prevent the desialylation problem in glycoprotein production, resulting improved protein quality during the entire cell culture process. © 2006 Wiley Periodicals, Inc. [source] 2243: Update on inherited ocular developmental diseaseACTA OPHTHALMOLOGICA, Issue 2010GCM BLACK Purpose To provide an overview of progress in understanding of the genetics of developmental ocular disease. Methods A systematic review, including case presentations, to illustrate insights into genes underlying developmental ocular disorders: Results Studies suggest that, in developed countries, between a third and a half of the diagnoses underlying childhood blind or partial-sighted registration are genetic while a number of other ,non-genetic' conditions also have a substantial genetic contribution. Such a figure is likely to be an underestimate. Although most of these conditions are rare, many of the issues regarding diagnosis and counselling apply to the group as a whole and it is therefore possible to consider a common approach to many aspects of their clinical management. An important challenge, for example, is to improve genetic counselling for patients affected by, and at risk of, disorders that may be caused by a genetic change in one of many possible genes, which typifies many inherited conditions associated with blindness (developmental ocular disorders, early-onset retinal dystrophies, congenital cataract). Most diagnostic genetic testing currently being undertaken focuses on single genes; this will be illustrated for ocular conditions such as retinoblastoma, Norrie disease and microphthalmia. However future prospects will focus upon use of new higher throughput technologies (e.g Microarray technologies). Conclusion The recent identification of genes underlying, for example, anophthalmia/microphthalmia spectrum (e.g. VSX2, SOX2, BCOR), anterior segment dysgenesis (e.g. PITX2, FOXC1, FOXE3) and early,onset retinal disorders (e.g. ADVIRC, RPE65) has shed light on the pathways and processes underlying a range of the biological processes underlying ocular development. [source] Implantable cardioverter defibrillators for prevention of sudden cardiac DeathCLINICAL CARDIOLOGY, Issue 1 2007Rishi Sukhija M.D. Abstract Despite the multiple advances in the field of cardiovascular medicine, the incidence of sudden cardiac death (SCD) continues to rise. Of all SCDs, <25% occur in individuals deemed at high risk by current risk-stratification algorithms; hence, these risk-stratification algorithms are not satisfactory. Until better markers are identified to risk stratify patients, we will see an increasing use of implantable cardioverter defibrillators (ICDs). However, even with the increase in defibrillator use, the impact on overall incidence of SCD may only be modest, as many individuals experience SCD as the first manifestation of cardiovascular disease. Another important challenge is widespread availability of automated external defibrillators and effective utilization of public access defibrillation programs for timely and appropriate management of out-of-hospital victims with cardiac arrest. This review discusses the current understanding on SCD, risk stratification, and management aimed at reducing SCD, particularly with the use of ICDs. Copyright © 2007 John Wiley & Sons, Ltd. [source] Campylobacter infections of the pericardium and myocardiumCLINICAL MICROBIOLOGY AND INFECTION, Issue 4 2005C. Uzoigwe Abstract Members of the genus Campylobacter are notorious for their ability to cause gastroenteritis. However, increasing numbers of case reports now suggest that they may have a wider pathogenic repertoire. Pericarditis and myocarditis are increasingly being recognised as sequelae of Campylobacter infection. Although rare, these presentations are important, as misdiagnosis may result in inappropriate thrombolysis or angioplasty, with potential accompanying complications. Extraintestinal Campylobacter infections, and the resulting pathogenesis, remain an important challenge for the 21st century, particularly as immunocompromised patients are likely to become increasingly common. [source] Fluoride ingestion from toothpaste: conclusions of European Union-funded multicentre projectCOMMUNITY DENTISTRY AND ORAL EPIDEMIOLOGY, Issue 2004Denis M. O'Mullane Abstract,-, An important challenge encountered in this multicentred project was the need to take account of the different cultural and legal differences between the seven sites when agreeing the protocol. Examples such as access to registers of births and subject consent dictated that there were some differences in the methods used in the different sites. The data presented showed that it was possible to train and calibrate a number of examiners in a standardized photographic method for recording enamel fluorosis. This method has a number of important advantages for the objective monitoring of enamel fluorosis over time. There were considerable differences between the seven sites in the formulations of the toothpaste used and in the pattern of their use. The results indicate that it is possible to agree and adopt a standardized method for measuring fluoride ingestion from toothpaste. The aesthetic impact of enamel fluorosis seemed low in the populations included in this project, but further work is required on this issue. [source] | ||||||||||||||||||||||||||||||||||||||||