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Selected AbstractsA Framework for Estimating Benefits of Using Auctions in Revenue Management,DECISION SCIENCES, Issue 3 2002Tim Baker ABSTRACT We develop a stochastic model to explore the benefits of incorporating auctions in revenue management. To the best of our knowledge the extant literature on modeling in revenue management has not considered auctions. We consider three models, namely, a traditional fixed price (non-auction) model, a pure auction model, and a hybrid auction model and evaluate their revenue performance under a variety of conditions. The hybrid approach outperforms the other two in all 24 scenarios and yields an average revenue increase of 16.1% over the next best. A surprise finding is that there is no significant difference between the performance of the fixed price and pure auction approaches. A sensitivity analysis reveals that the relative superiority of the hybrid revenue management strategy is reasonably robust. [source] Random controls on semi-rhythmic spacing of pools and riffles in constriction-dominated riversEARTH SURFACE PROCESSES AND LANDFORMS, Issue 11 2001Douglas M. Thompson Abstract Average pool spacing between five and seven bankfull widths has been documented in environments throughout the world, but has limited theoretical justification in coarse-bedded and bedrock environments. Pool formation in coarse-bedded and bedrock channels has been attributed to bedrock and boulder constrictions. Because the spacing of these constrictions may be irregular in nature, it is difficult to reconcile pool-formation processes with the supposedly rhythmic spacing of pools and riffles. To address these issues, a simulation model for pool and riffle formation is used to demonstrate that semi-rhythmic spacing of pools with an approximate spacing of five to seven bankfull widths can be recreated from a random distribution of obstructions and minimum pool- and riffle-length criteria. It is assumed that a pool,riffle couplet will achieve a minimum length based on dominant-discharge conditions. Values for the minimum-length assumption are based on field data collected in New England and California, while the theoretical basis relies on the demonstrated hydraulic response of individual pools to elongation. Results from the simulations show that the location of pools can be primarily random in character, but still assume an average spacing between four and eight bankfull widths for a variety of conditions. Field verification data generally support the model but highlight a highly skewed distribution of pool-forming elements and pool spacing. The relation between pool spacing and bankfull widths is attributed to the common geometric response of these features to dominant-discharge conditions. Copyright © 2001 John Wiley & Sons, Ltd. [source] Review article: Hypertonic saline use in the emergency departmentEMERGENCY MEDICINE AUSTRALASIA, Issue 4 2008Colin J Banks Abstract Hypertonic saline (HS) is being increasingly used for the management of a variety of conditions, most notably raised intracranial pressure. This article reviews the available evidence on HS solutions as they relate to emergency medicine, and develops a set of recommendations for its use. To conclude, HS is recommended as an alternative to mannitol for treating raised intracranial pressure in traumatic brain injury. HS is also recommended for treating severe and symptomatic hyponatremia, and is worth considering for both recalcitrant tricyclic antidepressant toxicity and for cerebral oedema complicating paediatric diabetic ketoacidosis. HS is not recommended for hypovolaemic resuscitation. [source] CLINICAL STUDY: Prolactin response to fenfluramine in abstinent, alcohol-dependent patientsADDICTION BIOLOGY, Issue 3-4 2008Richard J. Porter ABSTRACT It has been suggested that serotonin (5HT) function is abnormal in alcoholics even during abstinence. The prolactin response to fenfluramine (PRF) is generally believed to reflect the activity of the 5HT system and has been previously used to investigate 5HT activity in a variety of conditions, including alcoholism. The origin of the cortisol (CORT) response to fenfluramine is less clear. The objectives of this paper are to examine the prolactin (PRL) and CORT response to dl -fenfluramine in a large cohort of males with alcohol dependence who had been abstinent for 3 weeks, and to compare this with an age-matched control group. Ninety-four subjects with a DSM-III-R diagnosis of moderate to severe alcohol dependence who had been abstinent for 3 weeks, and 23 control subjects underwent neuroendocrine challenge with dl -fenfluramine (10 mg per 10 kg body weight). PRL and CORT responses were measured. No significant difference was found in PRF between abstinent, alcoholic patients and controls (F = 2.7, d.f. = 1.115, P = 0.10). CORT response was significantly lower in abstinent alcoholics than in controls (F = 10.0, d.f. = 1.116, P = 0.002). The results suggest no clear difference in 5HT function between abstinent alcoholics and healthy controls. The reduced CORT response in abstinent alcoholics further supports evidence of hypofunction of the adrenocortical system in this group. [source] Quantifying carbon sequestration as a result of soil erosion and deposition: retrospective assessment using caesium-137 and carbon inventoriesGLOBAL CHANGE BIOLOGY, Issue 12 2007TIMOTHY ANDREW QUINE Abstract The role of soil erosion in the global carbon cycle remains a contested subject. A new approach to the retrospective derivation of erosion-induced quantitative fluxes of carbon between soil and atmosphere is presented and applied. The approach is based on the premise that soil redistribution perturbs the carbon cycle by driving disequilibrium between soil carbon content and input. This perturbation is examined by establishing the difference between measured carbon inventories and the inventories that would be found if input and content were in dynamic equilibrium. The carbon inventory of a profile in dynamic equilibrium is simulated by allowing lateral and vertical redistribution of carbon but treating all other profile inputs as equal to outputs. Caesium-137 is used to derive rates of vertical and lateral soil redistribution. Both point and field-scale estimates of carbon exchange with the atmosphere are derived using the approach for a field subject to mechanized agricultural in the United Kingdom. Sensitivity analysis is undertaken and demonstrates that the approach is robust. The results indicate that, despite a 15% decline in the carbon content of the cultivation layer of the eroded part of the field, this area has acted as a net sink of 11 ± 2 g C m,2 yr,1 over the last half century and that in the field as a whole, soil redistribution has driven a sink of 7 ± 2 g C m,2 yr,1 (6 ± 2 g C m,2 yr,1 if all eroded carbon transported beyond the field boundary is lost to the atmosphere) over the same period. This is the first empirical evidence for, and quantification of, dynamic replacement of eroded carbon. The relatively modest field-scale net sink is more consistent with the identification of erosion and deposition as a carbon sink than a carbon source. There is a clear need to assemble larger databases with which to evaluate critically the carbon sequestration potential of erosion and deposition in a variety of conditions of agricultural management, climate, relief, and soil type. In any case, this study demonstrated that the operation of erosion and deposition processes within the boundaries of agricultural fields must be understood as a key driver of the net carbon cycle consequences of cultivating land. [source] Optimization of Full-Scale Permanganate ISCO System Operation: Laboratory and Numerical StudiesGROUND WATER MONITORING & REMEDIATION, Issue 4 2008Jeffrey L. Heiderscheidt Laboratory characterization studies, one-dimensional flow-through studies, and numerical model simulations were conducted to examine site conditions and system features that may have adversely affected in situ chemical oxidation (ISCO) performance at the Naval Training Center's (NTC) Operable Unit 4 located in Orlando, Florida, and to identify potential ISCO system modifications to achieve the desired remediation performance. At the NTC site, ISCO was implemented using vertical injection wells to deliver potassium permanganate into a ground water zone for treatment of tetrachloroethylene and its breakdown products. However, oxidant distribution was much more limited than anticipated. Characterization studies revealed that the ground water zone being treated by ISCO was very fine sand with a small effective particle size and low uniformity coefficient, along with a high organic carbon content, high natural oxidant demand (NOD), and a high ground water dissolved solids concentration, all of which contributed to full-scale ISCO application difficulties. These site conditions contributed to injection well permeability loss and an inability to achieve the design oxidant injection flow rate, limiting the actual oxidant distribution at the site. Flow-through experiments demonstrated that more favorable oxidant delivery and distribution conditions are enabled by applying a lower oxidant concentration at a faster delivery rate for a greater number of pore volumes. Numerical simulations, run for a variety of conditions (injection/extraction well flow rates, injected oxidant concentration, amount of NOD present, and NOD oxidation rate), also revealed that low,oxidant concentration injection at a high flow rate is a more effective method to deliver the required mass of oxidant to the target treatment zone. [source] Impact of treating facilities' volume on survival for early-stage laryngeal cancer,HEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 9 2009Amy Y. Chen MD Abstract Background Treatment at a high-volume facility has been associated with better outcomes in a variety of conditions. The relationship between volume and survival from laryngeal cancer has not been examined previously. Methods A total of 11,446 early-stage laryngeal cancer patients (1996,1998) who reported to the National Cancer Database (NCDB) were analyzed. Proportional hazards regression was used to assess the relationship between survival and treatment volume controlling for other factors associated with survival. Results Treatment at low-volume facilities was associated with a significantly increased likelihood of death (hazard ratio 1.20, 95% CI 1.04,1.38). Surgical resection, as compared with radiation treatment, was associated with lower mortality (HR 0.74, 95% CI 0.69,0.80). Conclusion This study is the first to assess the relationship between survival and treatment volume in laryngeal cancer. Treatment at a high-volume facility is associated with better survival. Surgical treatment rather than radiation was also associated with better survival, although we could not control for confounders that may bias treatment selection. © 2009 Wiley Periodicals, Inc. Head Neck, 2009 [source] Selective Hydrogenation of 5-Ethoxymethylfurfural over Alumina-Supported Heterogeneous CatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Erik-Jan Ras Abstract We report here the synthesis and testing of a set of 48 alumina-supported catalysts for hydrogenation of 5-ethoxymethylfurfural. This catalytic reaction is very important in the context of converting biomass to biofuels. The catalysts are composed of one main metal (gold, copper, iridium, nickel, palladium, platinum, rhodium, ruthenium) and one promoter metal (bismuth, chromium, iron, sodium, tin, tungsten). Using a 16-parallel trickle-flow reactor, we tested all 48 catalyst combinations under a variety of conditions. The results show that both substrate conversion and product selectivity are sensitive towards temperature changes and solvent effects. The best results of >99% yield to the desired product, 5-ethoxymethylfurfuryl alcohol, are obtained using an iridium/chromium (Ir/Cr) catalyst. The mechanistic implications of different possible reaction pathways in this complex hydrogenation system are discussed. [source] Mathematical improvements to maximum likelihood parallel factor analysis: theory and simulationsJOURNAL OF CHEMOMETRICS, Issue 4 2005Lorenzo Vega-Montoto Abstract A number of simplified algorithms for carrying out maximum likelihood parallel factor analysis (MLPARAFAC) for three-way data affected by different error structures are described. The MLPARAFAC method was introduced to establish the theoretical basis to treat heteroscedastic and/or correlated noise affecting trilinear data. Unfortunately, the large size of the error covariance matrix employed in the general formulation of this algorithm prevents its application to solve standard three-way problems. The algorithms developed here are based on the principle of alternating least squares, but differ from the generalized MLPARAFAC algorithm in that they do not use equivalent alternatives of the objective function to estimate the loadings for the different modes. Instead, these simplified algorithms tackle the loss of symmetry of the PARAFAC model by using only one representation of the objective function to estimate the loadings of all of the modes. In addition, a compression step is introduced to allow the use of the generalized algorithm. Simulation studies carried out under a variety of measurement error conditions were used for statistical validation of the maximum likelihood properties of the algorithms and to assess the quality of the results and computation time. The simplified MLPARAFAC methods are also shown to produce more accurate results than PARAFAC under a variety of conditions. Copyright © 2005 John Wiley & Sons, Ltd. [source] Structured reminiscence: an intervention to decrease depression and increase self-transcendence in older womenJOURNAL OF CLINICAL NURSING, Issue 2 2006Cynthia Kellam Stinson MSN Aims/objectives., The purpose of this study was to assess the effect of group reminiscing on depression and self-transcendence of older women residing in an assisted living facility in southeast Texas. There were two major objectives for this study. One objective was to determine if depression decreased in older women after structured reminiscence group sessions held twice weekly for a six-week period. A second objective was to determine if self-transcendence increased after structured reminiscence group sessions held twice weekly for a six-week period. Background., Reminiscence has been studied to determine its impact on a variety of conditions including but not limited to depression, self-esteem, fatigue, isolation, socialization, well-being, language acquisition and cognitive functioning. This review of research specifically focused on reminiscence, depression, self-transcendence and older people. Design/methods., Two groups were assessed at baseline, three and six weeks to answer the research questions. A sample of 24 women between the ages of 72 and 96 years were randomly assigned to either a reminiscence (experimental) group or the activity (control) group of the facility. Pearson's r was used to determine the magnitude of the relationship between subjects' responses on the Geriatric Depression Scale and the Self-Transcendence Scale. A mixed design analysis of variance (anova) was used to determine if there was a difference between the experimental and control groups on scores of the Geriatric Depression Scale and the Self-Transcendence Scale at baseline, three and six weeks. Conclusions., Data revealed a non-significant decrease in depression and increase in self-transcendence in the reminiscence group at the completion of six weeks, indicating a trend toward a positive result with reminiscence group sessions. The study also revealed an inverse relationship between depression and self-transcendence. These findings underscore the importance of screening older people for depression. Relevance to clinical practice., One of the primary modalities used for the treatment of depression in elderly women is medication. Antidepressant medications lead to harmful side effects without alleviating the underlying depression. For these reasons, there is a need to research alternative therapies for treatment of depression in the older female. Reminiscence offers a possible intervention for treatment of depression in older women. [source] An Odds Ratio Approach for Assessing Differential Distractor Functioning Effects under the Nominal Response ModelJOURNAL OF EDUCATIONAL MEASUREMENT, Issue 3 2008Randall D. Penfield Investigations of differential distractor functioning (DDF) can provide valuable information concerning the location and possible causes of measurement invariance within a multiple-choice item. In this article, I propose an odds ratio estimator of the DDF effect as modeled under the nominal response model. In addition, I propose a simultaneous distractor-level (SDL) test of invariance based on the results of the distractor-level tests of DDF. The results of a simulation study indicated that the DDF effect estimator maintained good statistical properties under a variety of conditions, and the SDL test displayed substantially higher power than the traditional Mantel-Haenszel test of no DIF when the DDF effect varied in magnitude and/or size across the distractors. [source] Functional MR imaging of the female pelvisJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2007Takashi Koyama MD Abstract Recent developments in MR techniques have magnified the roles and potential of MRI in the female pelvis. This article reviews the techniques and clinical applications of functional MRI (fMRI) of the female pelvis, including cine MRI, diffusion-weighted MRI (DWI), and dynamic contrast-enhanced (DCE)-MRI. Cine MRI is a useful tool for evaluating uterine contractility, including sustained contraction and peristalsis, in a variety of conditions and gynecologic disorders, and for evaluating pelvic-floor weakness. DWI can demonstrate abnormal signals in pathologic foci based on differences in molecular diffusion. It also enables the quantitative evaluation of the apparent diffusion coefficient (ADC), which may be useful for distinguishing malignant from benign tissues and monitoring therapeutic outcome. DCE-MRI has the potential to improve tumor detection and local staging, and can also provide quantitative information about perfusion of the tumor, which may be useful for both monitoring therapeutic effects and predicting therapeutic outcome. Understanding the roles played by functional MR techniques in the female pelvic region is beneficial not only for determining clinical applications, but also for developing further investigations with MRI. J. Magn. Reson. Imaging 2007;25:1101,1112. © 2007 Wiley-Liss, Inc. [source] Vulval lymphangiomata mimicking genital wartsJOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY & VENEREOLOGY, Issue 6 2003K Al Aboud ABSTRACT Genital warts can mimic a variety of conditions. We report a middle-aged pregnant woman with lymphangiectatic lesions on the vulva resembling warts. [source] Hepatic artery thrombosis after orthotopic liver transplantation: A review of nonsurgical causesLIVER TRANSPLANTATION, Issue 2 2001Sabrina Pastacaldi Hepatic artery thrombosis (HAT) is one of the principal causes of morbidity and graft loss following liver transplantation. There are several risk factors for the development of HAT; technical aspects of the arterial anastomosis are important particularly for early thrombosis, but the improvement of surgical technique has lessened this problem. Apart from technical causes, other risk factors include a variety of conditions such as low donor/recipient age ratio, immunologic factors, clotting abnormalities, tobacco use, and infections. In particular, cytomegalovirus (CMV) infection of endothelial cells has been recently suggested as an infective cause of HAT, as it is known to be followed by a rapid procoagulant response. Thus, latent CMV in an allograft may become activated and promote or contribute to vascular thrombosis. This review evaluates these aspects, focusing on data relating CMV infection or viremia to HAT following liver transplantation. [source] Evaluating planetesimal bow shocks as sites for chondrule formationMETEORITICS & PLANETARY SCIENCE, Issue 11 2004Fred J. CIESLA The formation of such shocks is modeled using a piecewise parabolic method (PPM) code under a variety of conditions. The results of this modeling are used as a guide to study chondrule formation in a one-dimensional, finite shock wave. This model considers a mixture of chondrule-sized particles and micron-sized dust and models the kinetic vaporization of the solids. We found that only planetesimals with a radius of ,1000 km and moving at least ,8 km/s with respect to the nebular gas can generate shocks that would allow chondrule-sized particles to have peak temperatures and cooling rates that are generally consistent with what has been inferred for chondrules. Planetesimals with smaller radii tend to produce lower peak temperatures and cooling rates that are too high. However, the peak temperatures of chondrules are only matched for low values of chondrule wavelength-averaged emissivity. Very slow cooling (<,100s of K/hr) can only be achieved if the nebular opacity is low, which may result after a significant amount of material has been accreted into objects that are chondrule-sized or larger, or if chondrules formed in regions of the nebula with small dust concentrations. Large shock waves of approximately the same scale as those formed by gravitational instabilities or tidal interactions between the nebula and a young Jupiter do not require this to match the inferred thermal histories of chondrules. [source] Understanding the human salivary metabolomeNMR IN BIOMEDICINE, Issue 6 2009Ienaka Takeda Abstract Saliva is a readily accessible biofluid that is important for the overall health, aiding in the chewing, swallowing, and tasting of food as well as the regulation mouth flora. As a first step to determining and understanding the human saliva metabolome, we have measured salivary metabolite concentrations under a variety of conditions in a healthy population with reasonably good oral hygiene. Using 1H NMR spectroscopy, metabolite concentrations were measured in resting (basal) and stimulated saliva from the same subject and compared in a cohort of healthy male non-smoking subjects (n,=,62). Almost all metabolites were higher in the unstimulated saliva when compared to the stimulated saliva. Comparison of the salivary metabolite profile of male smokers and non-smokers (n,=,46) revealed citrate, lactate, pyruvate, and sucrose to be higher and formate to be lower in concentration in smokers compared with non-smokers (p,<,0.05). Gender differences were also investigated (n,=,40), and acetate, formate, glycine, lactate, methanol, propionate, propylene glycol, pyruvate, succinate, and taurine were significantly higher in concentration in male saliva compared to female saliva (p,<,0.05). These results show that differences between male and female, stimulated and unstimulated, as well as smoking status may be observed in the salivary metabolome. Copyright © 2009 John Wiley & Sons, Ltd. [source] Short-wave diathermy: current clinical and safety practicesPHYSIOTHERAPY RESEARCH INTERNATIONAL, Issue 4 2002Nora Shields MISCP Abstract Background and Purpose Short-wave diathermy (SWD) is widely available, yet a comprehensive examination of current clinical practice remains absent from the literature. The present paper aims to assess clinical and safety issues in continuous (CSWD) and pulsed (PSWD) short-wave diathermy application and subsequently indicate areas for future research. Method A postal survey was carried out among 116 senior physiotherapists in 41 Irish hospital-based physiotherapy departments. Results The response rate to the study was 75%. Analysis found that PSWD was the preferred mode of treatment with 27% of respondents using it more than once daily. Respondents considered both modes of treatment indicated for a variety of conditions. CSWD was rated as an effective treatment for chronic osteoarthritis, polyarthritis, non-specific arthrosis and haematomas. PSWD was reported an effective modality for acute soft tissue injury, haematomas, acute osteoarthritis, sinusitis and rheumatoid arthritis. Dose selection varied greatly but tended to be based on the type, nature and duration of the condition. Analysis of safety practices uncovered concerning findings. Although a high level of agreement was found on measures for patient safety, 30% of respondents reported that no measures for operator safety were taken and only five respondents stated they remained a specified distance from SWD equipment. Measures to ensure the safety of other personnel in the physiotherapy department were also lacking. Conclusions Given the availability of SWD equipment and its apparent efficacy in certain conditions, future research should aim to establish this by means of controlled clinical trials. The findings on safety practices underline the urgent need for comprehensive guidelines to ensure the safety of operators, patients and the general public during SWD application. Copyright © 2002 Whurr Publishers Ltd. [source] Rotational molding cycle time reduction through surface enhanced molds: Part A,Theoretical studyPOLYMER ENGINEERING & SCIENCE, Issue 9 2007M.Z. Abdullah Rotational molding has been regarded as a plastic molding method with great potential. The process offers virtually stress-free products having no weld lines or material wastage, and utilizes relatively inexpensive molds. Yet its widespread growth is hindered due to long production cycle times, which are limited by the time required to heat up and cool down the mold and the product. To address this issue, efforts have been made to enhance heat transfer to and from molds, ultimately reducing cycle times. The application of extended and rough surfaces to molds is investigated here. The aim of this study is to predict reductions in cycle time due to the enhancement of mold surfaces (i.e. roughness-enhanced and pin-enhanced molds). By utilizing a combination of heat transfer correlations, numerical analysis, and an existing rotational molding process simulation, cycle time predictions were made. The average predicted cycle time reductions were ,21 and 32% for the roughness-enhanced and pin-enhanced molds considered, under a variety of conditions. POLYM. ENG. SCI., 47:1406,1419, 2007. © 2007 Society of Plastics Engineers [source] Confidence Intervals for Unbalanced Two-factor Gauge R&R StudiesQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 8 2005Liyun Gong Abstract We consider methods for constructing confidence intervals in a two-factor gauge repeatability and reproducibility (R&R) study when there are unequal replicates. We consider both random and mixed models and propose a general approach using unweighted sums of squares. Computer simulation is used to determine how well confidence intervals maintain the stated confidence level. The main conclusion is that the method performs well under a variety of conditions typically encountered in gauge R&R studies. The method is simple and the intervals can be computed in a spreadsheet program. Copyright © 2005 John Wiley & Sons, Ltd. [source] Practitioner Review: Clinical applications of pediatric hypnosisTHE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 8 2007Jeffrey I. Gold Background:, Over the past quarter century, hypnosis has been employed in a broad range of pediatric clinical settings; however, its efficacy and feasibility as a treatment approach for children and adolescents remain in question. Method:, Published studies on the role of clinical hypnosis in the management of specific pediatric medical and psychological conditions were identified and reviewed. Results:, Pediatric clinical hypnosis has been employed in diverse medical settings to treat primary conditions (e.g., enuresis), as well as to address factors related to management of the condition (e.g., skills training for asthma) or its treatment (e.g., burn dressing changes). Despite great breadth to the possible applications of pediatric hypnosis and many reported successes, much of the present research comprises case histories and small, uncontrolled group studies. Conclusion:, To date, research in pediatrics views clinical hypnosis as a promising tool with the potential to help manage a variety of conditions. However, additional research, particularly utilizing randomized, controlled methodologies and adequate sample sizes, is required. [source] The pair-functional method for direct solution of molecular structures.ACTA CRYSTALLOGRAPHICA SECTION A, Issue 2 2001The new pair-functional direct method has been implemented and tested. Like the Patterson function, the pairing force has valuable imaging properties at high resolution. Two simple iterative algorithms were designed to refine on the total pair potential and the normalized intensity correlation coefficient of an atomic model. The first algorithm is a peak-picking method which selects the best-paired high peaks from a density map and then uses the strong reflections to generate a new Fourier filtered map. The second algorithm, the pair-and-square method, uses a tangent formula step instead of the Fourier and is a little more efficient. Computational experiments on a point-atom grid model, with perfect data, reached exact ab initio solutions for up to 600 atoms. Point-atom models were also solved by searching for reduced structures that contained as few as one quarter of the atoms. Seeded searches, guided by a small known fragment, solved up to 30000 atoms on the grid. Realistic tests on actual molecules showed that Sheldrick's [Acta Cryst. (1990), A46, 467,473] test structures of 50,200 atoms can be solved under a variety of conditions. [source] The ,Indirect' Effects of Cytomegalovirus InfectionAMERICAN JOURNAL OF TRANSPLANTATION, Issue 11 2009R. B. Freeman Cytomegalovirus (CMV) remains the most important infection in the immunocompromized host even in the era of effective therapy. CMV is usually acquired early in life and can be transmitted by contact with infected body fluids. In the immunocompetent population, primary infection is almost always of little clinical consequence. However, CMV infection in immunocompromized patients, especially those naive to CMV exposure, can cause tissue invasive disease, severe symptoms and/or death. However, beyond these direct effects, increasing in vitro evidence is accumulating that suggests CMV has many other effects on the host's immune response which may explain some of the detrimental consequences for the immunosuppressed patient, and may also be partially responsible for a variety of conditions in immunocompetent individuals. In its latent state, CMV employs several mechanisms to evade detection by the host's immune system. The virus also employs other methods to take advantage of activation of the immune system and replicate in sites of inflammation. This review focuses on the immunosuppressive and inflammatory mechanisms that have been attributed to CMV and will relate them to some of the clinical sequellae that have been associated with the indirect effects of CMV infection. [source] Growth plasticity of the embryonic and fetal heartBIOESSAYS, Issue 12 2009Jörg-Detlef Drenckhahn Abstract The developing mammalian heart responds to a variety of conditions, including changes in nutrient availability, blood oxygenation, hemodynamics, or tissue homeostasis, with impressive growth plasticity. This ensures the formation of a functional and normal sized organ by birth. During embryonic and fetal development the heart is exposed to various physiological and potentially pathological changes in the intrauterine environment which dramatically impact on normal cardiac function, tissue composition, and morphology. This paper summarizes the mechanisms employed by the embryonic and fetal heart to adapt to various intrauterine challenges to prevent or minimize postnatal consequences of impaired cardiac development. Future investigations of this growth plasticity might lead to new therapeutic strategies for the prevention of cardiac disease in postnatal life. [source] A Multilevel Model for Continuous Time Population EstimationBIOMETRICS, Issue 3 2009Jason M. Sutherland Summary Statistical methods have been developed and applied to estimating populations that are difficult or too costly to enumerate. Known as multilist methods in epidemiological settings, individuals are matched across lists and estimation of population size proceeds by modeling counts in incomplete multidimensional contingency tables (based on patterns of presence/absence on lists). As multilist methods typically assume that lists are compiled instantaneously, there are few options available for estimating the unknown size of a closed population based on continuously (longitudinally) compiled lists. However, in epidemiological settings, continuous time lists are a routine byproduct of administrative functions. Existing methods are based on time-to-event analyses with a second step of estimating population size. We propose an alternative approach to address the twofold epidemiological problem of estimating population size and of identifying patient factors related to duration (in days) between visits to a health care facility. A Bayesian framework is proposed to model interval lengths because, for many patients, the data are sparse; many patients were observed only once or twice. The proposed method is applied to the motivating data to illustrate the methods' applicability. Then, a small simulation study explores the performance of the estimator under a variety of conditions. Finally, a small discussion section suggests opportunities for continued methodological development for continuous time population estimation. [source] Concentration of mammalian genomic DNA using two-phase aqueous micellar systemsBIOTECHNOLOGY & BIOENGINEERING, Issue 6 2009Foad Mashayekhi Abstract The concentration of biomarkers, such as DNA, prior to a subsequent detection step may facilitate the early detection of cancer, which could significantly increase chances for survival. In this study, the partitioning behavior of mammalian genomic DNA fragments in a two-phase aqueous micellar system was investigated using both experiment and theory. The micellar system was generated using the nonionic surfactant Triton X-114 and phosphate-buffered saline (PBS). Partition coefficients were measured under a variety of conditions and compared with our theoretical predictions. With this comparison, we demonstrated that the partitioning behavior of DNA fragments in this system is primarily driven by repulsive, steric, excluded-volume interactions that operate between the micelles and the DNA fragments, but is limited by the entrainment of micelle-poor, DNA-rich domains in the macroscopic micelle-rich phase. Furthermore, the volume ratio, that is, the volume of the top, micelle-poor phase divided by that of the bottom, micelle-rich phase, was manipulated to concentrate DNA fragments in the top phase. Specifically, by decreasing the volume ratio from 1 to 1/10, we demonstrated proof-of-principle that the concentration of DNA fragments in the top phase could be increased two- to nine-fold in a predictive manner. Biotechnol. Bioeng. 2009;102: 1613,1623. © 2008 Wiley Periodicals, Inc. [source] Preliminary crystallographic studies of glucose dehydrogenase from the promiscuous Entner,Doudoroff pathway in the hyperthermophilic archaeon Sulfolobus solfataricusACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 1 2005Alex Theodossis The hyperthermophilic archaeon Sulfolobus solfataricus grows optimally above 353,K and can metabolize glucose and its C4 epimer galactose via a non-phosphorylative variant of the Entner,Doudoroff pathway involving catalytically promiscuous enzymes that can operate with both sugars. The initial oxidation step is catalysed by glucose dehydrogenase (SsGDH), which can utilize both NAD and NADP as cofactors. The enzyme operates with glucose and galactose at similar catalytic efficiency, while its substrate profile also includes a range of other five- and six-carbon sugars. Crystals of the 164,kDa SsGDH homotetramer have been grown under a variety of conditions. The best crystals to date diffract to 1.8,Å on a synchrotron source, have orthorhombic symmetry and belong to space group P21212. Attempts are being made to solve the structure by MAD and MR. [source] Laparoscopic splenectomy: a suitable technique for children and adultsBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 3 2000T. J. Wheatley Aims: Splenectomy retains an important role in the management of certain haematological conditions that fail to respond to conventional medical therapy, and has traditionally been performed through a midline or left subcostal incision with patients requiring 5,7 days in hospital. The well recognized benefits of laparoscopic surgery should also apply to splenectomy. This study aimed to develop a safe and effective technique suitable for all age ranges and without the requirement for expensive stapling devices. Methods: An operative technique evolved over the 5-year period from 1994, from an initial six-port approach with the patient supine, to a four-port approach in a modified right lateral position, with locking surgical clips applied down a 5-mm port to vessels in the hilum, and removal of the spleen within a retrieval bag through a 4,6-cm Pfannanstiel incision. Data were collected prospectively for all patients undergoing laparoscopic splenectomy at Leicester Royal Infirmary, including demographic details, indication for surgery, duration of surgery, length of inpatient stay, transfusion requirement, postoperative complications and the response of the original condition to surgical intervention. Results: A total of 40 patients underwent laparoscopic splenectomy (14 children, 26 adults) for a variety of conditions (idiopathic thrombocytopenia (ITP) (n = 24), haemolytic anaemia (n = 9) or malignancy (n = 7)) with a median operating time of 180 min for the first 20 patients and 100 min for the second 20 (P < 0·0001), and median inpatient stay of 3 days for the first 20 patients and 2 days for the second 20 (P < 0·0003). None of the operations was converted to open surgery, five patients required blood and/or platelet transfusion perioperatively, none of the patients had major postoperative complications, 23 of the 24 patients with ITP developed normal platelet counts after operation, and all nine patients with haemolytic anaemia maintained a normal haemoglobin concentration after operation. Conclusions: Laparoscopic splenectomy can be performed safely and effectively in adults and children without the need for stapling devices. © 2000 British Journal of Surgery Society Ltd [source] Optimal Generic Advertising with a Rationed Related Good: The Case of Canadian Beef and Chicken MarketsCANADIAN JOURNAL OF AGRICULTURAL ECONOMICS, Issue 2 2002J. A. L. Cranfield An optimal advertising rule is derived for a good sold in an open market (beef) when a related substitute good (chicken) is production rationed and whose imports are subject to trade restrictions. Such a rule is developed using a multi-market equilibrium displacement model that reflects demand interrelatedness, open trade of the advertised good (beef), with rationed production and restricted trade of the related good (chicken). The optimal rule nests earlier optimal advertising rules under a variety of conditions. Results underscore the importance of accounting for cross-product advertising effects. When these effects are present (absent), the optimal generic beef advertising intensity in Canada is shown to fall (rise) with elimination of supply management in Canada's chicken sector. L'auteur dérive une règie sur l'optimisation de la publicité pour un produit vendu sur un marché libre (b,uf) en présence d'un produit de substitution rationné dont on restreint les importations. Pour parvenir à une telle règie, l'auteur a utilisé un modèle de déplacement du point d'équilibre sur un marché multiple illustrant les liens entre la demande des produits concernés, le libre-échange du produit faisant l'objet de la publicité (b,uf) et la restriction de la production et des importations du produit apparenté (poulet). La règie d'optimisation englobe les règles antérieures sur l'optimisation de la publicité dans diverses situations. Les résultats soulignent qu'il est important de prendre en compte les retombées de la publicité sur les autres produits. Au Canada, en présence (absence) de telles retombées, le degré optimal de publicité générique sur le b,uf diminue (augmente) avec l'abolition de la gestion de l'offre de poulet. [source] The effects of the caffeic acid phenethyl ester (CAPE) on erythrocyte membrane damage after hind limb ischaemia,reperfusionCELL BIOCHEMISTRY AND FUNCTION, Issue 5 2004Lülüfer Tamer Abstract Reactive oxygen species have been implicated in pathogenesis injury after ischaemia,reperfusion (I/R). Caffeic Acid Phenethyl Ester (CAPE), an active component of honeybee propolis extract, exhibits antioxidant and anti-inflammatory properties. The aim of this study was to investigate the effects of CAPE on erythrocyte membrane damage after hind limb I/R. Rats were divided into two groups: I/R and I/R with CAPE pre-treatment. They were anaesthetized with intramuscular ketamine 100,mg,kg,1. A 4-h I/R period was performed on the right hind limb of all animals. In the CAPE-treated group, animals received CAPE 10,,m by intraperitoneal injection 1,h before the reperfusion. At the end of the reperfusion period, a midsternotomy was performed. A 5-ml blood sample was withdrawn from the ascending aorta for biochemical assays. Serum and erythrocyte membrane MDA levels were significantly lower in the CAPE-treated group when compared to the I/R group (,p,=,0.001 and p<0.001, respectively). Erythrocyte membrane Na+ -K+ ATPases activity in the CAPE-treated group was significantly higher than the I/R group (,p<0.001). In conclusion, CAPE seems to be effective in protecting against oxidative stress. Therefore, we suggest that in order to decrease I/R injury, pre-administration of CAPE may be a promising agent for a variety of conditions associated with I/R. Copyright © 2004 John Wiley & Sons, Ltd. [source] Synthesis and Properties of (Triptycenedicarboxylatio)zinc Coordination NetworksCHEMISTRY - A EUROPEAN JOURNAL, Issue 23 2009Sergei Abstract Paddle wheels and pillars: Layered 3D metal,organic frameworks comprised of paddle-wheel coordination units are constructed under a variety of conditions to incorporate bridging ligands (as illustrated) that impart desired properties, such as guest-exchange behavior, luminescence, microporosity, and stability, to the material. (Triptycenedicarboxylato)zinc metal,organic frameworks (MOFs) based on paddle wheel secondary building units (SBUs) with different axial ligands have been prepared. The reproducible formation of the layered paddle-wheel structures from triptycenedicarboxylic acid (H2TDC) and zinc nitrate under various conditions seems to be characteristic of this acid and is utilized for the construction of 3D frameworks by a pillaring approach. We attempted to bring additional functionalities into MOFs by employing the appropriate pillaring ligands, for example, bis(4-pyridyl)- s -tetrazine and bis(4-pyridyl)-dimethoxy- p -phenylenedivinylene, and investigated certain properties of some MOF materials, such as guest-exchange behavior, luminescence, microporosity, and stability. [source] | ||||||||||||||||||||||||||||||||||