Major Impediment (major + impediment)

Distribution by Scientific Domains

Selected Abstracts

Clock synchronization in Cell/B.E. traces

M. Biberstein
Abstract Cell/B.E. is a heterogeneous multicore processor that was designed for the efficient execution of parallel and vectorizable applications with high computation and memory requirements. The transition to multicores introduces the challenge of providing tools that help programmers tune the code running on these architectures. Tracing tools, in particular, often help locate performance problems related to thread and process communication. A major impediment to implementing tracing on Cell is the absence of a common clock that can be accessed at low cost from all cores. The OS clock is costly to access from the auxiliary cores and the hardware timers cannot be simultaneously set on all the cores. In this paper, we describe an offline trace analysis algorithm that assigns wall-clock time to trace records based on their thread-local time stamps and event order. Our experiments on several Cell SDK workloads show that the indeterminism in assigning wall-clock time to events is low, on average 20,40 clock ticks (translating into 1.4,2.8,µs on the system used in our experiments). We also show how various practical problems, such as the imprecision of time measurement, can be overcome. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Combining data from multiple years or areas to improve variogram estimation

John F. Walter III
Abstract A requirement for geostatistical prediction is estimation of the variogram from the data. Often low sample size is a major impediment to elucidating a variogram even for a highly autocorrelated spatial process. This paper presents a methodology for improving variogram estimation when samples exist from multiple years or regions sharing a similar process for generating spatial autocorrelation. Such samples may come from annual monitoring programs for natural resources or from multiple geologic regions. As each set of samples contains some information on the spatial autocorrelation, combining information through the construction of a combined variogram cloud and binning to obtain a common variogram improves the estimation of the variogram. In both simulations and in real datasets of oyster abundance the method proposed here reduces the likelihood of failing to obtain a variogram from a set of samples and improves the efficiency of variogram estimation. In practice, the benefits obtained by estimating an otherwise elusive variogram generally outweigh the costs of using a slightly incorrect variogram model if different sampling stanzas are combined when they do not share the same spatial autocorrelation. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Seed roasting improves the oxidative stability of canola (B.,napus) and mustard (B.,juncea) seed oils

Chakra Wijesundera
Abstract Animal fats and partially hydrogenated vegetable oils (PHVO) have preferentially been used for deep-frying of food because of their relatively high oxidative stability compared to natural vegetable oils. However, animal fats and PHVO are abundant sources of saturated fatty acids and trans fatty acids, respectively, both of which are detrimental to human health. Canola (Brassica napus) is the primary oilseed crop currently grown in Australia. Canola quality Indian mustard (Brassica juncea) is also being developed for cultivation in hot and low-rainfall areas of the country where canola does not perform well. A major impediment to using these oils for deep-frying is their relatively high susceptibility to oxidation, and so any processing interventions that would improve the oxidative stability would increase their prospects of use in commercial deep-frying. The oxidative stability of both B.,napus and B.,juncea crude oils can be improved dramatically by roasting the seeds (165,°C, 5,min) prior to oil extraction. Roasting did not alter the fatty acid composition or the tocopherol content of the oils. The enhanced oxidative stability of the oil, solvent-extracted from roasted seeds, is probably due to 2,6-dimethoxy-4-vinylphenol produced by thermal decarboxylation of the sinapic acid naturally occurring in the canola seed. [source]

Women's traditional fishery and alternative aquatic resource livelihood strategies in the Southern Cameroonian Rainforest

Abstract, To inform the development of alternative livelihoods, the women's traditional alok fishery in the Campo-Ma'an National Park and buffer zone of southern Cameroon were studied over 15 months. Participatory rural appraisal was used to characterise livelihood strategies among 45 households. Thirty-three cultured crops, nine farmed animal species and 65 non-timber forest products, including 31 bushmeat species are cultivated in, or harvested from, the forest. Transport is a major impediment to commercial trade of all local products. In 16 alok fishing events, average weight of fish harvested was 5.14 kg per 280 m of stream distributed among an average of 23 fishers for a return of 220 g person,1 or 40 g fish h,1 over 5 h of work. Fish and crustacean standing stock was 25 g per linear metre or 167 t when extrapolated to the zone. Implications for rainforest livelihoods in light of the Millennium Development Goals are discussed. [source]

Expression of multidrug resistance-associated protein 1 in invasive ovarian carcinoma: implication for prognosis

Areeg Faggad
Aims:, Multidrug resistance is a major impediment in chemotherapeutic treatment of ovarian carcinoma patients. The aim of this study was to investigate the expression of multidrug resistance-associated protein 1 (MRP1) and to assess the possible associations with clinicopathological variables and patient outcome in primary ovarian carcinoma. Methods and results:, Tumour specimens from 129 patients were obtained before chemotherapy and analysed by immunohistochemistry on tissue microarrays, and by real-time reverse transcriptase-polymerase chain reaction on RNA extracted from formalin-fixed paraffin-embedded tissue specimens using a new technique. Significantly increased MRP1 protein expression was observed in high-grade tumours (P = 0.005) and advanced International Federation of Gynaecology and Obstetrics stages (P = 0.036). On univariate Kaplan,Meier analysis, patients with higher expression of MRP1 protein had significantly decreased overall survival (P = 0.006). On multivariate Cox regression analysis, MRP1 protein expression retained its significance as an independent negative prognostic marker for overall survival (hazard ratio = 6.52, P = 0.003). Furthermore, MRP1 expression correlated with topoisomerase II, expression both at mRNA and protein level (P < 0.001 and P = 0.023, respectively). Conclusion:, In summary, in patients with primary ovarian cancer, overexpression of MRP1 is an adverse marker for patient outcome and cancer aggressiveness. Our data provide a translational basis for further clinical studies on the predictive value of MRP1 expression for response to chemotherapy. [source]

The Role of Trust in Low-Income Mothers' Intimate Unions

Linda M. Burton
Recent scholarship concerning low rates of marriage among low-income mothers emphasizes generalized gender distrust as a major impediment in forming sustainable intimate unions. Guided by symbolic interaction theory and longitudinal ethnographic data on 256 low-income mothers from the Three-City Study, we argue that generalized gender distrust may not be as influential in shaping mothers' unions as some researchers suggest. Grounded theory analysis revealed that 96% of the mothers voiced a general distrust of men, yet that distrust did not deter them from involvement in intimate unions. Rather, the pivotal ways mothers enacted trust in their partners were demonstrated by 4 emergent forms of interpersonal trust that we labeled as suspended, compartmentalized, misplaced, and integrated. Implications for future research are discussed. [source]

General linearized biexponential model for QSAR data showing bilinear-type distribution

Peter Buchwald
Abstract A major impediment of many QSAR-type analyses is that the data show a maximum or minimum and can no longer be adequately described by linear functions that provide unrivaled simplicity and usually give good description over more restricted ranges. Here, a general linearized biexponential (LinBiExp) model is proposed that can adequately describe data showing bilinear-type distribution as a function of not just often-employed lipophilicity descriptors (e.g., log P) but as a function of any descriptor (e.g., molecular volume). Contrary to Hansch-type parabolic models, LinBiExp allows the natural extension of linear models and fitting of asymmetrical data. It is also more general and intuitive than Kubinyi's model as it has a more natural functional form. It was obtained by a differential equation-based approach starting from very general assumptions that cover both static equilibriums and first-order kinetic processes and that involve abstract processes through which the concentration of the compound of interest in an assumed "effect" compartment is connected to its "external" concentration. Physicochemical aspects placing LinBiExp within the framework of linear free energy relationship (LFER) approaches are presented together with illustrative applications in various fields such as toxicity, antimicrobial activity, anticholinergic activity, and glucocorticoid receptor binding. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:2355-2379, 2005 [source]

Training subspecialty nurses in developing countries: Methods, outcome, and cost

Judith A. Wilimas MD
Abstract Background As infections are controlled in developing countries, other pediatric subspeciality programs such as oncology become increasingly important. A major impediment to the development of such programs is a lack of trained nurses. Therefore, education of pediatric subspecialty nurses becomes a priority. Procedure We describe three models we have used for education of pediatric oncology nurses: a short series of classes or lectures with additional training of key nurses, an expanded 12 week series of classes at centers combining didactic and clinical instruction and a regional residential school offering regular 12 week courses in theory and clinical practice. Results Cost analysis showed that the cost per nurse trained was, respectively, $3,700; $4,350; and $5,500. Early effectiveness indicators show that retention rates are high, home institutions are satisfied, and nurses trained shared their knowledge with other nurses and improved nursing practices. Conclusions Programs to teach subspecialty nursing in developing countries are effective and can improve medical care. Such programs should be based on past experience and evaluated as to cost and effectiveness. Med Pediatr Oncol 2003;41:136,140. © 2003 Wiley-Liss, Inc. [source]

Detection of urinary biomarkers for early diagnosis of acute renal allograft rejection by proteomic analysis

Xiongfei Jia
Abstract Acute allograft rejection has been recognized as a major impediment to improved success in renal transplantation. Timely detection and control of rejection are very important for the improvement in long-term renal allograft survival. Thus, biomarkers for early diagnosis of acute rejection are required urgently to clinical medication. This study seeks to search for such biomarker candidates by comparing patients' pre-treatment urinary protein profiling with their post-treatment urinary protein profiling. A total of 15 significantly and consistently down-regulated protein candidates were identified. Among them, alpha-1-antichymotrypsin precursor (AACT), tumor rejection antigen gp96 (GP96) and Zn-Alpha-2-Glycoprotein (ZAG) were selected for further analysis. The results indicated that Western Blot assay of AACT, GP96 and ZAG had advanced the diagnosis time of acute renal rejection by 3 days, compared with current standard clinical observation and laboratory examination. Furthermore, the double-blind detection revealed that the accuracy, sensitivity and specificity of the diagnosis of acute renal rejection of AACT, GP96 and ZAG were 66.67%/100%/60%, 83.33%/100%/80% and 66.67%/100%/60%, respectively, and 100%/100%/100% in combination. In conclusion, urinary protein AACT, GP96 and ZAG could be a set of potential biomarkers for early non-invasive diagnosis of the acute rejection after renal transplantation. [source]

Capacity development for education service delivery in Pakistan: Top-down devolution

David Watson
Abstract The historical, political, socio-cultural and institutional context in the public service of Pakistan is not auspicious for the delivery of social services such as education. The then military regime introduced radical devolution reforms in 2001 that promised improvements in service delivery by enhancing accountabilities and capacities for change in local government. However the political economy of this top-down devolution has proved contentious. It established new power structures and authorities over resources at local levels but without concurrent efforts to enhance service delivery capacities. This article examines capacity issues in two cases of capacity development in education service delivery in Pakistan's largest province. The Punjab Education Sector Reform Programme (PESRP) was managed by a provincial-level implementation unit; the Strategic Policy Unit (SPU) of City District Government Faisalabad was a local government project supported by technical co-operation. Both delivered major improvements in education delivery capacity in just 4 years, after decades of delivery stagnation and worsening education indicators. The sustainability of these initiatives is in doubt, as political economy factors remain a major impediment to devolved service delivery in Pakistan. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Asymmetric asset price reaction to news and arbitrage risk

John A. Doukas
Abstract This study documents that high book-to-market (value) and low book-to-market (glamour) stock prices react asymmetrically to both common and firm-specific information. Specifically, we find that value stock prices exhibit a considerably slow adjustment to both common and firm-specific information relative to glamour stocks. The results show that this pattern of differential price adjustment between value and glamour stocks is mainly driven by the high arbitrage risk borne by value stocks. The evidence is consistent with the arbitrage risk hypothesis, predicting that idiosyncratic risk, a major impediment to arbitrage activity, amplifies the informational loss of value stocks as a result of arbitrageurs' (informed investors) reduced participation in value stocks because of their inability to fully hedge idiosyncratic risk. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Thoracic aneurysm repair: Managing severe tortuosity with brachiofemoral traction

Christos Lioupis MD
Abstract Challenging anatomy of the thoracic aorta is often encountered, and aortic tortuosity may be a major impediment to the propulsion of the stent-graft. Traction on both ends of a guidewire, with one end exiting the right upper extremity and the other end exiting the lower extremity, is an excellent option to manage thoracic aorta tortuosity. Careful application of simple guidelines may lessen associated risks and improve safety. © 2007 Wiley-Liss, Inc. [source]

Knowledge Translation in International Emergency Medical Care

L. Kristian Arnold MD
More than 90% of the world population receives emergency medical care from different types of practitioners with little or no specific training in the field and with variable guidance and oversight. Emergency medical care is being recognized by actively practicing physicians around the world as an increasingly important domain in the overall health services package for a community. The know-do gap is well recognized as a major impediment to high-quality health care in much of the world. Knowledge translation principles for application in this highly varied young domain will require investigation of numerous aspects of the knowledge synthesis, exchange, and application domains in order to bring the greatest benefit of both explicit and tacit knowledge to increasing numbers of the world's population. This article reviews some of the issues particular to knowledge development and transfer in the international domain. The authors present a set of research proposals developed from a several-month online discussion among practitioners and teachers of emergency medical care in 16 countries from around the globe and from all economic strata, aimed at improving the flow of knowledge from developers and repositories of knowledge to the front lines of clinical care. [source]

Exploring the Dynamics of Calix[4]pyrrole: Effect of Solvent and Fluorine Substitution

Ramón Blas Dr.
Abstract Molecular dynamics simulations show that calix[4]pyrrole (CP) and octafluorocalix[4]pyrrole (8F-CP) are extremely flexible molecules. CP mainly adopts the 1,3-alternate conformation in all the solvents, although the percentage of alternative conformations increases in polar solvents, especially those with good hydrogen-bonding acceptor properties. However, in the case of 8F-CP, the cone conformation is the most populated in some solvents. Transitions between conformers are common and fast, and both CP and 8F-CP can adopt the cone conformation needed for optimum interaction with anions more easily than would be predicted on the basis of previous gas-phase calculations. Furthermore, the present studies show that when a fluoride anion is specifically placed initially in close proximity to CP and 8F-CP in their respective 1,3-alternate conformations, an extremely fast change to the cone conformation is observed in both cases. The results suggest that preorganization does not represent a major impediment to anion-binding for either CP or 8F-CP, and that ion-induced conformational changes can follow different mechanisms depending on the solvent and the chemical substituents present on the calix[4]pyrrole beta-pyrrolic positions. [source]

Thoracic organ donor characteristics associated with successful lung procurement

Doff B McElhinney
Purpose: A shortage of suitable donors is the major impediment to clinical lung transplantation. The rate of lung recovery from potential donors is lower than that for other organs. The purpose of this study was to evaluate what factors could be modified to improve the rate of cadaver lung recovery. Methods: We performed a retrospective review of records from all thoracic organ donors procured by the California Transplant Donor Network between 1 January 1995 and 31 May 1997 (251 donors) to determine which donor management factors were associated with an increased likelihood of successful lung procurement. Results: There were 88 lung donors (L) and 163 donors from which hearts but no lungs were procured (H). Longer time to donor network referral was associated with a reduced chance for successful lung procurement. Donor age, cause of death, and time of admission were not important factors. Most donors in this study had an acceptable A-a gradient at admission to the hospital but lung function deteriorated in group H. Corticosteroid usage and initially clear breath sounds were independent predictors of successful procurement by multivariate analysis. Conclusions: Early contact with the donor referral network, and corticosteroids may help to improve the lung procurement rate from potential donors. [source]

Tourism in Dubai: overcoming barriers to destination development

Joan C. Henderson
Abstract The Middle East as a whole attracts comparatively few visitors, and political events in the current century have generated new uncertainties and tensions which seem likely to further discourage tourists and investors. Additional barriers relate to poor accessibility, a perceived lack of conventional attractions and limited promotion. Despite these apparently unfavourable circumstances, international tourism has been adopted by the Dubai authorities as a core element in a programme of economic diversification. They have invested heavily in expensive facilities, as well as undertaken extensive marketing, and the outcome has been strong growth in tourism. There are great expectations of the future, reflected in the setting of very high arrival targets. However, there are also several constraints that might inhibit progress, with a need to review strategies. The experience of Dubai thus serves to illustrate factors that are critical to destination development, major impediments and approaches to overcoming these. Copyright © 2006 John Wiley &Sons, Ltd. [source]

Radiation: Facts, fallacies and phobias

DR Wigg
Summary There is frequent debate in the media and the scientific published reports about the use of radiation for diagnosis and treatment, the benefits and risks of the nuclear industry, uranium mining and the storage of radioactive wastes. Driving this debate is increasing concern about reliance on fossil fuels for power generation for which alternatives are required. Unfortunately, there is generally a poor understanding of the relevant basic sciences compounded by widespread irrational fear of irradiation (radiation phobia). Radioactivity, with special reference to uranium and plutonium is simply described. How radiation affect tissues and the potential hazards to individuals and populations are explained. The origins of radiation phobia and its harmful consequences are examined. Whether we like it or not, Australia is heavily involved in the uranium industry by virtue of having one-third of the world's known reserves, exports of which are worth approximately $470m annually. As this paper has been written as simply as possible, it may also be of interest to readers who may have had little scientific training. It may be downloaded from the web using references provided in this article. It is concluded that ignorance and fear are major impediments to rational debate on radiation issues. [source]


Vincent J. Lovko
Water quality, microbial contamination, prior fish health, and variable results have been major impediments to identifying the cause and mechanism of fish mortality in standard aquarium-format Pfiesteria bioassays. Therefore, we developed a sensitive 96-h larval fish bioassay for assessing Pfiesteria spp. pathogenicity using six-well tissue culture plates and 7-day-old larval cyprinodontid fish. We used the assay to test pathogenicity of several clonal lines of Pfiesteria piscicida Steidinger and Burkholder and P. shumwayae Glasgow and Burkholder that had been cultured with algal prey for 2 to 36 months. The P. shumwayae cultures exhibited 80%,100% cumulative mortality in less than 96 h at initial zoospore densities of approximately 1000 cells·mL,1. No fish mortalities occurred with P. piscicida at identical densities or in controls. In a dose-response assay, we demonstrated a strong positive correlation between dinospore density and fish mortality in a highly pathogenic culture of P. shumwayae, generating a 96-h LD50 of 108 zoospores·mL,1. Additionally, we applied the assay to evaluate a 38-L P. shumwayae bioassay that was actively killing fish and compared results with those from exposures of juvenile tilapia (Oreochromis niloticus) in a 500-mL assay system. Water from the fish-killing 38-L assay was filtered and centrifuged to produce fractions dominated by dinoflagellates, bacteria, or presumed ichthyotoxin (cell-free fraction). After 96 h, the larval fish assay exhibited 50%,100% cumulative mortality only in fractions containing dinoflagellates, with no mortalities occurring in the other fractions. The 500-mL bioassay with tilapia produced inconsistent results and demonstrated no clear correlation between mortality and treatment. The new larval fish bioassay was demonstrated as a highly effective method to verify and evaluate dinoflagellate pathogenicity. [source]

Somatic Embryogenesis in Leguminous Plants

PLANT BIOLOGY, Issue 2 2000
P. Lakshmanan
Abstract: This review examines recent advances in the induction and development of somatic embryos in leguminous plants. Emphasis has been given to identify the current trends and successful strategies for the establishment of somatic embryogenic systems, particularly in the economically important species. It appears that, in legumes, somatic embryogenesis can be realized relatively easily especially in young meristematic tissues such as immature embryos and developing leaves. In the majority of the species examined, chlorophenoxyacetic acids remained the most active inductive compounds; however, the new generation growth regulators such as thidiazuron are emerging as successful alternatives for high-frequency direct regeneration of somatic embryos, even from well differentiated explant tissues. Low-frequency embryo production, poor germination and conversion of somatic embryos into plantlets and somaclonal variation are the major impediments limiting the utility of somatic embryogenesis for biotechnological applications in legumes. These limitations, however, may be considerably reduced in the near future, as more newly developed growth regulators with specific morphogenic targets become available for experimentation. From the published data, it is apparent that more effort should be given to develop repetitive embryogenic systems with high frequency of germination and regeneration, since such systems will find immediate application in mass propagation and other crop improvement programmes. As our understanding of various morphogenic processes, including growth and differentiation of zygotic embryos, is fast expanding, it is conceivable that development of highly efficient somatic embryogenic systems with practical application can be anticipated, at least for the important leguminous crops, in the foreseeable future. [source]