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Pooling
Kinds of Pooling Terms modified by Pooling Selected AbstractsHypofrontality in schizophrenia: a meta-analysis of functional imaging studiesACTA PSYCHIATRICA SCANDINAVICA, Issue 4 2004K. Hill Objective:, Hypofrontality is not a well-replicated finding in schizophrenia either at rest or under conditions of task activation. Method:, Studies comparing whole brain and frontal blood flow/metabolism in schizophrenic patients and normal controls were pooled. Voxel-based studies were also combined to examine the pattern of prefrontal activation in schizophrenia. Results:, Whole brain flow/metabolism was reduced in schizophrenia to only a small extent. Resting and activation frontal flow/metabolism were both reduced with a medium effect size. Duration of illness significantly moderated resting hypofrontality, but the moderating effects of neuroleptic treatment were consistent with an influence on global flow/metabolism only. Pooling of voxel-based studies did not suggest an abnormal pattern of activation in schizophrenia. Conclusion:, Meta-analysis supports resting hypofrontality in schizophrenia. Task-activated hypofrontality is also supported, but there is little from voxel-based studies to suggest that this is associated with an altered pattern of regional functional architecture. [source] Pooling as a response to the competing interests in corporate group collapse in AustraliaINTERNATIONAL INSOLVENCY REVIEW, Issue 1 2010Mary Wyburn There has always been a problem for company law in effectively responding to the financial collapse of a corporate group. In the past, a range of partial responses have been proposed and some implemented. The 2007 insolvency amendments introduced another partial solution, statutory pooling. This paper discusses the competing interests in a corporate group collapse, how Australian corporate law has so far dealt with group collapse and the implications of the 2007 statutory pooling amendments. Copyright © 2010 John Wiley & Sons, Ltd. [source] Meta-analysis: levamisole improves the immune response to hepatitis B vaccine in dialysis patientsALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 6 2010F. Fabrizi Summary Background, Patients undergoing maintenance dialysis often fail to mount protective antibodies to hepatitis B virus surface antigen (HBsAg) following vaccination against hepatitis B virus (HBV). Some authors have suggested that levamisole improves immune response to HBV vaccine in dialysis population. However, consistent information on this issue does not exist. Aim, To evaluate efficacy and safety of levamisole as adjuvant to hepatitis B virus (HBV) vaccine in dialysis patients by performing a systematic review of the literature with a meta-analysis of clinical trials. Methods, We used the random-effects model of DerSimonian and Laird, with heterogeneity and sensitivity analyses. Only trials comparing the seroresponse rate in study subjects (levamisole plus HBV vaccine) vs. controls (HBV vaccine alone) were included. The end point of interest was the rate of patients showing seroprotective anti-hepatitis B titres at completion of HBV vaccine schedule in study vs. control groups. Results, We identified four studies involving 328 unique patients on regular dialysis. Only prospective, randomized clinical trials (RCTs) were included. Pooling of study results showed a significant increase in response rates among study (levamisole plus HBV vaccine) vs. control (HBV vaccine alone) patients; the pooled Odds Ratio was 2.432 (95% Confidence Intervals, 1.34; 4.403), P = 0.002. No study heterogeneity was found. These results did not change in various subgroups of interest. Conclusions, Our meta-analysis showed that levamisole significantly improves immune response to hepatitis B vaccine in dialysis population. The limited number of patients precluded more conclusions. [source] Pooling-Based Data Interpolation and BackdatingJOURNAL OF TIME SERIES ANALYSIS, Issue 1 2007Massimiliano Marcellino C32; C43; C82 Abstract., Pooling forecasts obtained from different procedures typically reduces the mean square forecast error and more generally improve the quality of the forecast. In this paper, we evaluate whether pooling-interpolated or-backdated time series obtained from different procedures can also improve the quality of the generated data. Both simulation results and empirical analyses with macroeconomic time series indicate that pooling plays a positive and important role in this context also. [source] The impact of hepatitis C virus infection on survival in dialysis patients: meta-analysis of observational studiesJOURNAL OF VIRAL HEPATITIS, Issue 10 2007F. Fabrizi Summary., The impact of hepatitis C virus (HCV) infection on mortality of patients receiving regular dialysis remains unclear. The assessment of the natural history of HCV in dialysis population is difficult because of the low progression of HCV-related liver disease over time and the reduced life expectancy in patients with end-stage renal disease. The aim of the study was to conduct a systematic review of the published medical literature concerning the impact of HCV infection on the survival of patients undergoing maintenance dialysis. The relative risk of mortality was regarded as the most reliable outcome end-point. Study-specific relative risks were weighted by the inverse of their variance to obtain fixed- and random-effects pooled estimates for mortality with HCV across the published studies. We identified seven studies involving 11 589 unique patients on maintenance dialysis; two (29%) were case,control studies. Pooling of study results demonstrated that presence of anti-HCV antibody was an independent and significant risk factor for death in patients on maintenance dialysis. The summary estimate for adjusted relative risk (aRR) (all-cause mortality) was 1.34 with a 95% confidence interval (CI) of 1.13,1.59. Heterogeneity statistics, Ri = 0.48 (P -value by Q -test = 0.13). In a sensitivity analysis including only (n = 5) cohort studies, the pooled aRR was 1.38 (95% CI, 1.20,1.59); heterogeneity statistics Ri = 0.46. As a cause of death, hepatocellular carcinoma and liver cirrhosis were significantly more frequent among anti-HCV-positive than -negative dialysis patients. Our meta-analysis indicates that anti-HCV-positive patients on dialysis have an increased risk of mortality compared with HCV-negative patients. The excess risk of death in HCV-positive patients may be at least partially attributed to chronic liver disease with its attendant complications. [source] Estimation of gene frequency and heterozygosity from pooled samplesMOLECULAR ECOLOGY RESOURCES, Issue 3 2002K. Ritland Abstract Pooling of DNA samples can significantly reduce the effort of population studies with DNA markers. I present a statistical model and numerical method for estimating gene frequency when pooled DNA is assayed for the presence/absence of alleles. Analytical and Monte-Carlo methods examined estimation variance and bias, and hence optimal pool size, under a triangular allele frequency distribution. For gene frequency of rarer alleles, the optimal number of pooled individuals is approximately the inverse of the gene frequency. For heterozygosity, the optimal pool is approximately half the allele number; this results in pools containing, on average, 60% of possible alleles. [source] THE VALUE OF SKU RATIONALIZATION IN PRACTICE (THE POOLING EFFECT UNDER SUBOPTIMAL INVENTORY POLICIES AND NONNORMAL DEMAND)PRODUCTION AND OPERATIONS MANAGEMENT, Issue 1 2003JOSÉ A. ALFARO Several approaches to the widely recognized challenge of managing product variety rely on the pooling effect. Pooling can be accomplished through the reduction of the number of products or stock-keeping units (SKUs), through postponement of differentiation, or in other ways. These approaches are well known and becoming widely applied in practice. However, theoretical analyses of the pooling effect assume an optimal inventory policy before pooling and after pooling, and, in most cases, that demand is normally distributed. In this article, we address the effect of nonoptimal inventory policies and the effect of nonnormally distributed demand on the value of pooling. First, we show that there is always a range of current inventory levels within which pooling is better and beyond which optimizing inventory policy is better. We also find that the value of pooling may be negative when the inventory policy in use is suboptimal. Second, we use extensive Monte Carlo simulation to examine the value of pooling for nonnormal demand distributions. We find that the value of pooling varies relatively little across the distributions we used, but that it varies considerably with the concentration of uncertainty. We also find that the ranges within which pooling is preferred over optimizing inventory policy generally are quite wide but vary considerably across distributions. Together, this indicates that the value of pooling under an optimal inventory policy is robust across distributions, but that its sensitivity to suboptimal policies is not. Third, we use a set of real (and highly erratic) demand data to analyze the benefits of pooling under optimal and suboptimal policies and nonnormal demand with a high number of SKUs. With our specific but highly nonnormal demand data, we find that pooling is beneficial and robust to suboptimal policies. Altogether, this study provides deeper theoretical, numerical, and empirical understanding of the value of pooling. [source] Population modelling of the effect of inogatran, at thrombin inhibitor, on ex vivo coagulation time (APTT) in healthy subjects and patients with coronary artery diseaseBRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 1 2001Marie Cullberg Aims, The purpose of this study was to characterize the relationship between the degree of anticoagulation, assessed by APTT, and the plasma concentration of inogatran in healthy subjects and in patients with coronary artery disease. Methods, Data from five phase I studies in 78 healthy males and two phase II multicentre studies in 948 patients of both sexes with unstable angina pectoris or non-Q-wave myocardial infarction were evaluated. A total of 3296 pairs of concentration-APTT samples were obtained before, during, and after intravenous infusions of inogatran. Mixed effects modelling was used for population pharmacodynamic analysis of the drug effect and for describing the variability in baseline APTT. Results, The population mean baseline APTT was 29 s, but large variations between individuals (s.d. 3.6 s) were observed. The variability between studies (1.3 s) and centres (1.8 s) were of less importance, though statistically significant. APTT increased in a nonlinear manner with increasing inogatran concentration and the relationship was well described by a combined linear and Emax model. A significant part of the overall variability could be ascribed to the APTT reagent and equipment used at the different study centres. These method-dependent differences were compensated for by including the lower limit of the normal reference range as a covariate, affecting both baseline and Emax, in the model. For the typical healthy subject and patient, the method-corrected population mean parameters were: APTTbaseline 35 and 31 s, slope 8.0 and 5.8 s l µmol,1, Emax 36 and 34 s, and EC50 0.54 and 0.72 µmol l,1, respectively. The model predicted plasma concentration needed to double the APTT from the baseline value was 1.25 and 1.45 µmol l,1 in the healthy volunteer and patient, respectively. Conclusions, The nonlinear relationship between APTT and inogatran concentration in plasma was well described by a combined linear and Emax model. Pooling of data was made possible by incorporating a centre-specific characteristic of the assay method in the model. Patients had lower baseline APTT and appeared to have less pronounced effect of inogatran than young healthy subjects. [source] Compatibility of Government Guarantees with Flexibility in Canadian Wheat Price PoolingCANADIAN JOURNAL OF AGRICULTURAL ECONOMICS, Issue 1 2001James Unterschultz Financial option theory is used to evaluate Canadian Wheat Board (CWB) price pooling and associated government guarantees. Price guarantees and final payments on the pool can be viewed as special financial derivative products. Financial models are used to evaluate alternative pricing flexibility alternatives within the constraints of the CWB price pooling system and at the same time to provide a measure of the CWB dollars at risk associated with offering these contracts. Flexible pricing alternatives are incompatible with a government price guarantee that is valuable. The CWB dollar risk associated with flexible pricing could be substantial. Les auteurs recourent à la théorie des contrats d'option pour évaluer le système de fixation de prix communs par la Commission canadienne du blé (CCB) et les garanties connexes du gouvemement. On peut considérer les prix garantis et les paiements finals du pool comme un type particulier de produits dérivés. Des modéles financiers permettent d'évaluer d'autres méthodes qui autoriseraient la fluctuation des prix dans les contraintes du systéme de pool de la CCB, mais serviraient aussi à mesurer les risques financiers de la CCB associés à la proposition de contrats. Les autres méthodes de fixation des prix sont incompatibles avec une garantie valable du gouvemement au niveau des prix. La CCB courrait le risque de penes importantes si elle adoptait une politique de variation des prix. [source] Effect of stents in reducing restenosis in small coronary arteries: A meta-analysisCATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS, Issue 4 2004FSCAI, Paul T. Vaitkus MD Abstract The ability of stents to reduce restenosis was established in larger coronary arteries. Clinical trials of stenting in smaller vessels have yielded conflicting results due in part to their sample sizes. The aim of this meta-analysis was to increase the statistical power by pooling data from these clinical trials. Trials were identified from Medline search, review of recent cardiology meetings' abstracts, and manual review of bibliographies. Studies were included if they were prospective randomized controlled trials. Endpoints examined included a dichotomized definition of angiographic restenosis, target lesion revascularization (TLR), target vessel revascularization (TVR), or any repeat revascularization. Pooling of data was performed by calculating a Mantel-Haenszel odds ratio (OR). The analysis included 2,598 patients enrolled in eight clinical trials. Stenting significantly reduced restenosis (OR = 0.62; 95% CI = 0.61,0.63). Concordantly, stenting reduced TLR (OR = 0.49), TVR (OR = 0.90), and any revascularization (OR = 0.48). This meta-analysis supports the hypothesis that stenting reduces restenosis in small coronary arteries as well as in larger coronary arteries. The apparent discordant result of individual clinical trials was due in part to underpowering related to small sample sizes. Catheter Cardiovasc Interv 2004;62:425,429. © 2004 Wiley-Liss, Inc. [source] A meta-analysis of the association of physical activity with reduced risk of colorectal cancerCOLORECTAL DISEASE, Issue 3 2005A. K. A. Samad Abstract Background Physical activity may be associated with reduced risk of colorectal cancer. The main aim of this paper is to review the available evidence for a link between exercise and large bowel cancer. Methods A Cochrane-type methodology was performed. Data extracted included, type of study, type of physical activity measured and the numerical results. The risk ratios (RR) of the studies have been pooled according to the type of study, type of exercise, type of cancer and sex. Pooling was undertaken using fixed effect meta-analysis. A random effect meta-analysis was used where substantial heterogeneity existed. Result Data from 19 cohort studies showed a statistically significant reduction in the risk of colon cancer in physically active males, RR being 0.79 (95% CI 0.72,0.87) and 0.78 (95% CI 0.68,0.91) for occupational and recreational activities, respectively. In women only recreational activities are protective against colon cancer (RR = 0.71, 95%CI 0.57,0.88). Case-control studies showed significantly reduced risks of colon cancer in both sexes irrespective of the type of activity. No protection against rectal cancer is seen in either sex. Conclusion There is considerable evidence that physical activity is associated with reduced risk of colon cancer in both males and females. [source] Flow cytometry antibody screening using pooled red cells,CYTOMETRY, Issue 2 2010Dong Il Won Abstract Background: For red cell alloantibody screening, the column agglutination technique (CAT) is used extensively, and flow cytometry (FC) screening has recently been demonstrated to be accurate, rapid, and cost effective. We attempted to determine whether the high sensitivity of FC allows pooling of screening red cells, which is generally not an acceptable technique in CAT. Methods: For FC screening, a commercial two-cell screening panel was utilized for the preparation of individual cells (CSi), as well as pooled cells diluted 1 in 2 (CSp), and 1 in 3 (CS1/3). Another panel was pooled from 120 randomly selected group O donors (RSp). Results: Comparing the endpoint titrations of serial dilutions, CS1/3 was found to be one dilution, on the average, less sensitive than CSi. In 33 CAT-positive patient samples, the sensitivities of CSi and CSp did not differ significantly without polyethylene glycol (PEG) (30/33, 26/33, respectively, P = 0.125), although they did differ significantly with PEG (32/33, 25/33, respectively, P = 0.016). The percentages of reactive cells among the total cells from RSp were roughly proportional to the relevant antigen frequencies of the local donors. Conclusions: A trend toward reduced sensitivity was observed using pooled red cells, even via FC. Pooled cells from randomly selected group O donors may be employed as another method by which the characteristics of known antibodies might be assessed. © 2009 Clinical Cytometry Society [source] In-Class Simulation of Pooling Safety StockDECISION SCIENCES JOURNAL OF INNOVATIVE EDUCATION, Issue 2 2005D. Brent Bandy ABSTRACT In managing business process flows, safety stock can be used to protect against stockouts due to demand variability. When more than one location is involved, the concept of aggregation enables the pooling of demands and associated inventories, resulting in improved service levels without increasing the total level of safety stock. This pooling of safety stock can be done physically by consolidating inventory in one location, or by using virtual centralization, where inventories are kept at decentralized locations, but information is centralized. In teaching the concept of pooling safety stock, a simple in-class simulation can be helpful in demonstrating why the approach works. The approach presented here involves operations for a company where total product demand is constant, but there are two products and product mix can vary. The simulation can also be implemented using an electronic spreadsheet for classes that are taught on the Internet. A quiz was given to two sections, one that experienced the simulation and one that did not. A comparison of the results from the quiz provided evidence of the effectiveness of the simulation in helping students understand the impact of pooling safety stock. In addition, a brief anonymous survey that was administered in the section that had the simulation provided further support for the effectiveness of the simulation. [source] Incentive Problems With Unidimensional Hidden Characteristics: A Unified ApproachECONOMETRICA, Issue 4 2010Martin F. Hellwig This paper develops a technique for studying incentive problems with unidimensional hidden characteristics in a way that is independent of whether the type set is finite, the type distribution has a continuous density, or the type distribution has both mass points and an atomless part. By this technique, the proposition that optimal incentive schemes induce no distortion "at the top" and downward distortions "below the top" is extended to arbitrary type distributions. However, mass points in the interior of the type set require pooling with adjacent higher types and, unless there are other complications, a discontinuous jump in the transition from adjacent lower types. [source] Refining the results of a whole-genome screen based on 4666 microsatellite markers for defining predisposition factors for multiple sclerosisELECTROPHORESIS, Issue 14 2004René Gödde Abstract Multiple sclerosis (MS) is a demyelinating disease of the central nervous system with a complex genetic background. In order to identify loci associated with the disease, we had performed a genome screen initially using 6000 microsatellite markers in pooled DNA samples of 198 MS patients and 198 controls. Here, we report on the detailed reanalysis of this set of data. Distinctive features of microsatellites genotyped in pooled DNA causing false-positive association or masking existing association were met by improved evaluation and refined correction factors in the statistical analyses. In order to assess potential errors introduced by DNA pooling and genotyping, we resurveyed the experiment in a subset of microsatellite markers using de novo -composed DNA pools. True MS associations of markers were verified via genotyping all individual DNA samples comprised in the pools. Microsatellites share characteristically superb information content but they do not lend themselves to automation in very large scale formats. Especially after DNA pooling many artifacts of individual marker systems require special attention and treatment. Therefore, in the near future comprehensive whole-genome screens may rather be performed by typing single nucleotide polymorphisms on chip-based platforms. [source] Efficacy of single-agent bortezomib vs. single-agent thalidomide in patients with relapsed or refractory multiple myeloma: a systematic comparisonEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 2 2007H. Miles Prince Abstract Objective:, To conduct a systematic review of the efficacy of single-agent bortezomib vs. single-agent thalidomide in patients with relapsed/refractory multiple. Methods:, Publications in English from 1966 to June 2005 (MEDLINE, EMBASE, Cochrane library), publication reference lists, Janssen-Cilag data-on-file and abstracts from recent multiple myeloma conferences were reviewed. Prospective studies containing at least a single arm of either treatment group with n,30 were included. Studies adding dexamethasone for non-responders were excluded. Statistical pooling was performed for response rate and overallsurvival. Results:, One bortezomib study (n = 333, NEJM 2005, 352; 2487,98) and 15 thalidomide (n = 1007) studies met these criteria and were included. Patient baseline characteristics including age, gender, IgG : IgA, disease duration and beta-2 microglobulin were well matched except that 48% of bortezomib patients had received prior thalidomide. Response rate, defined as serum M-protein reduction ,50%, was 53% for patients receiving bortezomib vs. 32% for thalidomide (P < 0.001, n = 10 studies). Response rate determined by European Group for Blood and Marrow Transplantation (EBMT) criteria was 41% for patients receiving bortezomib vs. 22% for thalidomide (P < 0.001, n = 4 studies). Conclusion:, Bortezomib was associated with a significantly higher response rate and complete remission rate using both M-protein and EBMT criteria. [source] Stereoselective biosynthesis of chloroarylpropane diols by the basidiomycete Bjerkandera adusta: exploring the roles of amino acids, pyruvate, glycerol and phenyl acetyl carbinolFEMS MICROBIOLOGY LETTERS, Issue 1 2003Peter James Silk Abstract Bjerkandera adusta produces many chlorometabolites including chlorinated anisyl metabolites (CAMs) and 1-arylpropane-1,2-diols (1, 2, 3, 4) as idiophasic metabolic products of l -phenylalanine. These diols are stereoselectively biosynthesized from a C7 -unit (benzylic, from l -phenylalanine) and a C2 -unit, of unknown origin, as predominantly erythro (1R,2S) enantiomers. Of the labeled amino acids tested as possible C2 -units, at the 4,10 mM level, none were found to efficiently label the 2,3-propane carbons of the diols. However, glycine (2- 13C), l -serine (2,3,3-d3) and l -methionine (methyl-d3) entered the biomethylation pathway. Neither pyruvate (2,3- 13C2), acetate (1,2- 13C2), acetaldehyde (d4) nor ethanol (ethyl-d5) labeled the 2,3-propane carbons of the diols at the 4,10 mM level. Pyruvate (2,3- 13C2) and l -serine (2,3,3-d3) (which also entered the biomethylation pathway) did, however, effectively label the 2,3-propane carbons of the ,-ketols and diols at the 40 mM level as evidenced by mass spectrometry. Glycerol (1,1,2,3,3-d5) also appeared to label one of the 2,3-propane carbons (ca. 5% as 2H2 in the C3 side chain) as suggested by mass spectrometric data and also entered the biomethylation pathway, likely via amino acid synthesis. Glycerol (through pyruvate), therefore, likely supplies C2 and C3 of the propane side chain with arylpropane diol biosynthesis. Incubation of B. adusta with synthetic [2- 2H1,2- 18O]-glycerol showed that neither 2H nor 18O were incorporated in the ,-ketols or diols. The oxygen atom on the C2 of the ketols/diols, therefore, does not appear to come from the oxygen atom on the C2 of glycerol. Glycerol, however, can readily form l -serine (which can then form pyruvate via PLP/serine dehydratase and involve transamination washing out the 18O label and providing the oxygen from water), and can then go on to label the C2 -unit. Labeled ,-ketol, phenyl acetyl carbinol (5) (PAC; ring-d5, 2,3- 13C2 propane) cultured with B. adusta leads to stereospecific reduction to the (1R,2S)-diol (6) (ring-d5 and 2,3- 13C2); in all other metabolites produced, the 2,3- 13C2 label is washed out. Incubation of the fungus with 4-fluorobenzaldehyde (13) produces a pooling of predominantly erythro (1R,2S) 1-(4,-fluorophenyl)-1,2-propane diol (18 as diacetate) (through the corresponding ,-ketols 16, 17). Blocking the para-position with fluorine thus appears to prevent ring oxygenation and also chlorination, forcing the conclusion that para-ring oxygenation precedes meta-chlorination. [source] Case report of a focal nodular hyperplasia-like nodule present in cirrhotic liverHEPATOLOGY RESEARCH, Issue 5 2008Sho Takahashi An 81-year-old female was referred to Sapporo Medical University Hospital because of a nodular lesion 20 mm in diameter found in the liver S8 during follow-up for type C liver cirrhosis. Abdominal ultrasonography showed a capsule-like structure, and contrast computed tomography revealed hypervascularity at the early phase and inner pooling of the contrast medium with ring enhancement at the late phase. Magnetic resonance T2-weighted imaging (T2WI) demonstrated a hyperintensity nodule with further hyperintensity signals in some parts of the nodule, and the signal pattern differed from that of typical fibrosis. SPIO-magnetic resonance imaging showed partial hypointensity signals by T2WI, which indicated the presence of Kupffer cells. Angiography did not show a spoke-wheel pattern. The results by imaging modalities indicated that the nodule was atypical for hepatocellular carcinoma (HCC) and focal nodular hyperplasia (FNH), and liver nodule biopsy was performed for histological diagnosis. Compared with the background liver, the nodule revealed high cellular density, cellular dysplasia at the periphery, a pseudo-crypt structure and irregular hepatic cord arrangement in some parts of the nodule. Among them, there was immature fibrous tissue containing arterioles with muscular hypertrophy. There has been no report of well-differentiated HCC with a central scar, and this case was presumed to be an FNH-like nodule with dysplasia physically associated with cirrhotic tissue. [source] Assessment of the increase in variability when combining volumetric data from different scannersHUMAN BRAIN MAPPING, Issue 2 2009Santiago Reig Abstract In multicenter MRI studies, pooling of volumetric data requires a prior evaluation of compatibility between the different machines used. We tested the compatibility of five different scanners (2 General Electric Signa, 2 Siemens Symphony, and a Philips Gyroscan) at five different sites by repeating the scans of five volunteers at each of the sites. Using a semiautomatic method based on the Talairach atlas, and SPM algorithms for tissue segmentation (multimodal T1 and T2, or T1-only), we obtained volume measurements of the main brain lobes (frontal, parietal, occipital, temporal) and for each tissue type. Our results suggest that pooling of multisite data adds small error for whole brain measurements, intersite coefficient of variation (CV) ranging from 1.8 to 5.2%, respectively, for GM and CSF. However, in the occipital lobe, intersite CV can be as high as 11.7% for WM and 17.3% for CSF. Compared with the intersite, intrasite CV values were always much lower. Whenever possible, T1 and T2 tissue segmentation methods should be used because they yield more consistent volume measurements between sites than T1-only, especially when some of the scans were obtained with different sequence parameters and pixel size from those of the other sites. Our study shows that highest compatibility among scanners would be obtained using equipments of the same manufacturer and also image acquisition parameters as similar as possible. After validation, data from a specific ROI or scanner showing values markedly different from the other sites might be excluded from the analysis. Hum Brain Mapp, 2009. © 2007 Wiley-Liss, Inc. [source] The bootstrap and cross-validation in neuroimaging applications: Estimation of the distribution of extrema of random fields for single volume tests, with an application to ADC mapsHUMAN BRAIN MAPPING, Issue 10 2007Roberto Viviani Abstract We discuss the assessment of signal change in single magnetic resonance images (MRI) based on quantifying significant departure from a reference distribution estimated from a large sample of normal subjects. The parametric approach is to build a test based on the expected distribution of extrema in random fields. However, in conditions where the variance is not uniform across the volume and the smoothness of the images is moderate to low, this test may be rather conservative. Furthermore, parametric tests are limited to datasets for which distributional assumptions hold. This paper investigates resampling methods that improve statistical tests for signal changes in single images in such adverse conditions, and that can be used for the assessment of images taken for clinical purposes. Two methods, the bootstrap and cross-validation, are compared. It is shown that the bootstrap may fail to provide a good estimate of the distribution of extrema of parametric maps. In contrast, calibration of the significance threshold by means of cross-validation (or related sampling without replacement techniques) address three issues at once: improved power, better voxel-by-voxel estimate of variance by local pooling, and adaptation to departures from ideal distributional assumptions on the signal. We apply the cross-validated tests to apparent diffusion coefficient maps, a type of MRI capable of detecting changes in the microstructural organization of brain parenchyma. We show that deviations from parametric assumptions are strong enough to cast doubt on the correctness of parametric tests for these images. As case studies, we present parametric maps of lesions in patients suffering from stroke and glioblastoma at different stages of evolution. Hum Brain Mapp 2007. © 2007 Wiley-Liss, Inc. [source] Duloxetine in acute major depression: review of comparisons to placebo and standard antidepressants using dissimilar methodsHUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 3 2009Paolo Girardi Abstract Background Randomized controlled trials (RCTs) of duloxetine (DLX), an inhibitor of both norepinephrine and serotonin transporters (SNRI), have tested its efficacy in acute major depressive disorder (MDD) versus placebo (PBO) or standard serotonin-reuptake inhibitors (SRIs) and require review, comparing analytical methods. Method Computerized searching to identify reports of RCTs of DLX in adult, acute MDD patients permitted meta-analytic pooling to estimate overall response and remission rates, to compare mixed-model, repeated measures (MMRM) versus last-observations-carried-forward (LOCF) analytical methods, and to assess relations of DLX dose to efficacy and adverse outcomes. Results We identified 17 RCTs involving 22 comparisons (DLX versus PBO [n,=,17) and DLX versus an SRI [n,=,16]), based on MMRM and LOCF methods that allowed estimates of response (,50% improvement of depression scores) or remission (final depression score ,7). There was a large overall DLX/PBO contrast (LOCF, RR,=,1.42 [CI: 1.31,1.53], p,<,0.0001, with a success rate of 65% [11/17]), and somewhat larger effects with MMRM in both response (MMRM: RR,=,1.48 [95%CI: 1.31,1.66] versus LOCF: RR,=,1.41 [CI: 1.28,1.56]; NNT 4.8 versus 6.5) and remission (MMRM: RR,=,1.61 [CI: 1.41,1.85] versus LOCF: RR,=,1.44 [CI: 1.27,1.63]; NNT,=,5.9 versus 8.9). Based on LOCF methods, dropout rates were similar with DLX and PBO (RR,=,1.04 [CI: 0.94,1.15]); DLX response was dose-dependent (r,=,+0.72, p,=,0.001), and RCT-dropout rates were inversely related to DLX dose, but possibly artifactually. Limitations RCTs involving DLX are limited, with few direct comparisons to standard antidepressants. Conclusions DLX has good evidence of efficacy in acute, adult MDD, especially at doses of 80,120,mg/day, but remains inadequately tested against standard alternatives. MMRM analyses yielded slightly superior FLX/PBO contrasts than older LOCF methods. Copyright © 2009 John Wiley & Sons, Ltd. [source] Accuracy and precision of different sampling strategies and flux integration methods for runoff water: comparisons based on measurements of the electrical conductivityHYDROLOGICAL PROCESSES, Issue 2 2006Patrick Schleppi Abstract Because of their fast response to hydrological events, small catchments show strong quantitative and qualitative variations in their water runoff. Fluxes of solutes or suspended material can be estimated from water samples only if an appropriate sampling scheme is used. We used continuous in-stream measurements of the electrical conductivity of the runoff in a small subalpine catchment (64 ha) in central Switzerland and in a very small (0·16 ha) subcatchment. Different sampling and flux integration methods were simulated for weekly water analyses. Fluxes calculated directly from grab samples are strongly biased towards high conductivities observed at low discharges. Several regressions and weighted averages have been proposed to correct for this bias. Their accuracy and precision are better, but none of these integration methods gives a consistently low bias and a low residual error. Different methods of peak sampling were also tested. Like regressions, they produce important residual errors and their bias is variable. This variability (both between methods and between catchments) does not allow one to tell a priori which sampling scheme and integration method would be more accurate. Only discharge-proportional sampling methods were found to give essentially unbiased flux estimates. Programmed samplers with a fraction collector allow for a proportional pooling and are appropriate for short-term studies. For long-term monitoring or experiments, sampling at a frequency proportional to the discharge appears to be the best way to obtain accurate and precise flux estimates. Copyright © 2006 John Wiley & Sons, Ltd. [source] Comparison of MicroSeal and System B/Obtura II obturation techniquesINTERNATIONAL ENDODONTIC JOURNAL, Issue 12 2003P. R. Cathro Abstract Aim, To compare the proportion of gutta-percha, sealer and voids following the filling of simulated root canals in plastic blocks using two warm gutta-percha techniques. Methodology, Ten simulated root canals in plastic blocks were prepared using System GT Rotary Files® and a .02 taper size 40 Quantec rotary nickel,titanium instrument and then filled with MicroSeal and Kerr EWT sealer. A further 10 simulated canals were prepared solely with System GT Rotary Files® and obturated with System B/Obtura II and Kerr EWT sealer. All blocks were sectioned at 1 mm intervals. The sectioned root fillings were photographed through a stereomicroscope and the resultant slides scanned. The images were analysed using adobe photoshop 6.0 to give the proportions of gutta-percha, sealer or void at each level. The data were analysed using unpaired Student's t -test and Mann,Whitney U -test. Results, The MicroSeal technique produced a dense homogeneous gutta-percha fill at the apical 1 and 2 mm levels similar to the System B/Obtura II technique, but further coronally the sealer became mixed into the MicroFlow gutta-percha producing a heterogeneous mass with significantly less (P < 0.05) solid gutta-percha in the root filling compared to System B/Obtura II. The MicroSeal technique generally had more pooling of cement than the System B technique, however, this was only significantly different (P < 0.05) at the 4 mm level. The System B/Obtura II obturation gave an average of 99.27% ± 1.09 gutta-percha fill at all levels. Conclusions, The MicroSeal technique produced a heterogeneous fill consisting of the MicroFlow Master Cone and gutta-percha from the MicroFlow Cartridge mixed with sealer. The System B/Obtura II technique produced a homogeneous fill at all levels. [source] Pooling as a response to the competing interests in corporate group collapse in AustraliaINTERNATIONAL INSOLVENCY REVIEW, Issue 1 2010Mary Wyburn There has always been a problem for company law in effectively responding to the financial collapse of a corporate group. In the past, a range of partial responses have been proposed and some implemented. The 2007 insolvency amendments introduced another partial solution, statutory pooling. This paper discusses the competing interests in a corporate group collapse, how Australian corporate law has so far dealt with group collapse and the implications of the 2007 statutory pooling amendments. Copyright © 2010 John Wiley & Sons, Ltd. [source] A regional frequency analysis of United Kingdom extreme rainfall from 1961 to 2000INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 11 2003H. J. Fowler Abstract Multi-day rainfall events are an important cause of recent severe flooding in the UK, and any change in the magnitude of such events may have severe impacts upon urban structures such as dams, urban drainage systems and flood defences and cause failures to occur. Regional pooling of 1-, 2-, 5- and 10-day annual maxima for 1961 to 2000 from 204 sites across the UK is used in a standard regional frequency analysis to produce generalized extreme value growth curves for long return-period rainfall events for each of nine defined climatological regions. Temporal changes in 1-, 2-, 5- and 10-day annual maxima are examined with L-moments using both a 10 year moving window and the fixed decades of 1961,70, 1971,80, 1981,90 and 1991,2000. A bootstrap technique is then used to assess uncertainty in the fitted decadal growth curves and to identify significant trends in both distribution parameters and quantile estimates. There has been a two-part change in extreme rainfall event occurrence across the UK from 1961 to 2000. Little change is observed at 1 and 2 days duration, but significant decadal-level changes are seen in 5- and 10-day events in many regions. In the south of the UK, growth curves have flattened and 5- and 10-day annual maxima have decreased during the 1990s. However, in the north, the 10-day growth curve has steepened and annual maxima have risen during the 1990s. This is particularly evident in Scotland. The 50 year event in Scotland during 1961,90 has become an 8-year, 11-year and 25-year event in the East, South and North Scotland pooling regions respectively during the 1990s. In northern England the average recurrence interval has also halved. This may have severe implications for design and planning practices in flood control. Copyright © 2003 Royal Meteorological Society [source] Cognitive leisure activities and their role in preventing dementia: a systematic reviewINTERNATIONAL JOURNAL OF EVIDENCE BASED HEALTHCARE, Issue 1 2010Cindy Stern BHSc(Hons) Abstract Background, Dementia inflicts a tremendous burden on the healthcare system. Identifying protective factors or effective prevention strategies may lead to considerable benefits. One possible strategy mentioned in the literature relates to participation in cognitive leisure activities. Aim, To determine the effectiveness of cognitive leisure activities in preventing Alzheimer's and other dementias among older adults. Inclusion criteria Types of participants.,Adults aged at least 60 years of age with or without a clinical diagnosis of dementia that resided in the community or care setting. Types of interventions.,Cognitive leisure activities, defined as activities that required a mental response from the individual taking part in the activity (e.g. reading). Types of outcomes.,The presence or absence of dementia was the outcome of interest. Types of studies.,Any randomised controlled trials, other experimental studies, as well as cohort, case,control and cross-sectional studies were considered for inclusion. Search strategy.,A search for published and unpublished studies in the English language was undertaken with no publication date restriction. Methodological quality, Each study was appraised independently by two reviewers using the standard Joanna Briggs Institute instruments. Data collection and analysis, Information was extracted from studies meeting quality criteria using the standard Joanna Briggs Institute tools. Because of the heterogeneity of populations and interventions, meta-analyses were not possible and results are presented in narrative form. Results, There were no randomised controlled trials located that met inclusion criteria. Thirteen observational studies were included in the review; the majority were cohort design. Because of the heterogeneity of interventions, the study design, the way in which they were grouped and the different stages of life they were measured at, statistical pooling was not appropriate. Studies were grouped by stage of adult life participation when interventions were undertaken, that is, early adulthood, middle adulthood and late life. Five out of six studies showed a positive association between participating in activities and a reduced risk of developing Alzheimer's disease and other dementias when interventions were undertaken in middle adulthood and six out of seven studies produced a positive association for late life participation. Results indicated that some activities might be more beneficial than others; however, results should be interpreted with caution because of the subjective nature of activity inclusion. Conclusion ,,Actively participating in cognitive leisure activities during mid- or late life may be beneficial in preventing the risk of Alzheimer's disease and other dementias in the elderly; however, the evidence is currently not strong enough to infer a direct causal relationship. ,,Participating in selected cognitive leisure activities may be more favourable than others but currently there is no strong evidence to recommend one over the other. [source] Effectiveness of simulation on health profession students' knowledge, skills, confidence and satisfactionINTERNATIONAL JOURNAL OF EVIDENCE BASED HEALTHCARE, Issue 3 2008Susan Laschinger Abstract Background, Despite the recent wave of interest being shown in high-fidelity simulators, they do not represent a new concept in healthcare education. Simulators have been a part of clinical education since the 1950s. The growth of patient simulation as a core educational tool has been driven by a number of factors. Declining inpatient populations, concerns for patient safety and advances in learning theory are forcing healthcare educators to look for alternatives to the traditional clinical encounter for skill acquisition for students. Objective, The aim of this review was to identify the best available evidence on the effectiveness of using simulated learning experiences in pre-licensure health profession education. Inclusion criteria,Types of studies: This review considered any experimental or quasi-experimental studies that addressed the effectiveness of using simulated learning experiences in pre-licensure health profession practice. In the absence of randomised controlled trials, other research designs were considered for inclusion, such as, but not limited to: non-randomised controlled trials and before-and-after studies. Types of participants: This review included participants who were pre-licensure practitioners in nursing, medicine, and rehabilitation therapy. Types of intervention(s)/phenomena of interest: Studies that evaluated the use of human physical anatomical models with or without computer support, including whole-body or part-body simulators were included. Types of outcome measures, Student outcomes included knowledge acquisition, skill performance, learner satisfaction, critical thinking, self-confidence and role identity. Search strategy, Using a defined search and retrieval method, the following databases were accessed for the period 1995,2006: Medline, CINAHL, Embase, PsycINFO, HealthSTAR, Cochrane Database of Systematic Reviews and ERIC. Methodological quality, Each paper was assessed by two independent reviewers for methodological quality prior to inclusion in the review using the standardised critical appraisal instruments for evidence of effectiveness, developed by the Joanna Briggs Institute. Disagreements were dealt with by consultations with a third reviewer. Data collection, Information was extracted from each paper independently by two reviewers using the standardised data extraction tool from the Joanna Briggs Institute. Disagreements were dealt with by consultation with a third reviewer. Data synthesis, Due to the type of designs and quality of available studies, it was not possible to pool quantitative research study results in statistical meta-analysis. As statistical pooling was not possible, the findings are presented in descriptive narrative form. Results, Twenty-three studies were selected for inclusion in this review including partial task trainers and high-fidelity human patient simulators. The results indicate that there is high learner satisfaction with using simulators to learn clinical skills. The studies demonstrated that human patient simulators which are used for teaching higher level skills, such as airway management, and physiological concepts are useful. While there are short-term gains in knowledge and skill performance, it is evident that performance of skills over time after initial training decline. Conclusion, At best, simulation can be used as an adjunct for clinical practice, not a replacement for everyday practice. Students enjoyed the sessions and using the models purportedly makes learning easier. However, it remains unclear whether the skills learned through a simulation experience transfer into real-world settings. More research is needed to evaluate whether the skills acquired with this teaching methodology transfer to the practice setting such as the impact of simulation training on team function. [source] Effectiveness of interventions that assist caregivers to support people with dementia living in the community: a systematic reviewINTERNATIONAL JOURNAL OF EVIDENCE BASED HEALTHCARE, Issue 2 2008Deborah Parker BA, MSocSci Executive summary Objectives, The objective of this review was to assess the effectiveness of interventions that assist caregivers to provide support for people living with dementia in the community. Inclusion criteria, Types of participants, Adult caregivers who provide support for people with dementia living in the community (non-institutional care). Types of interventions, Interventions designed to support caregivers in their role such as skills training, education to assist in caring for a person living with dementia and support groups/programs. Interventions of formal approaches to care designed to support caregivers in their role, care planning, case management and specially designated members of the healthcare team , for example dementia nurse specialist or volunteers trained in caring for someone with dementia. Types of studies, This review considered any meta-analyses, systematic reviews, randomised control trials, quasi-experimental studies, cohort studies, case control studies and observational studies without control groups that addressed the effectiveness of interventions that assist caregivers to provide support for people living with dementia in the community. Search strategy, The search sought to identify published studies from 2000 to 2005 through the use of electronic databases. Only studies in English were considered for inclusion. The initial search was conducted of the databases, CINAHL, MEDLINE and PsychINFO using search strategies adapted from the Cochrane Dementia and Cognitive Improvement Group. A second more extensive search was then conducted using the appropriate Medical Subject Headings (MeSH) and keywords for other available databases. Finally, hand searching of reference lists of articles retrieved and of core dementia, geriatric and psycho geriatric journals was undertaken. Assessment of quality, Methodological quality of each of the articles was assessed by two independent reviewers using appraisal checklist developed by the Joanna Briggs Institute and based on the work of the Cochrane Collaboration and Centre for Reviews and Dissemination. Data collection and analysis, Standardised mean differences or weighted mean differences and their 95% confidence intervals were calculated for each included study reported in the meta-analysis. Results from comparable groups of studies were pooled in statistical meta-analysis using Review Manager Software from the Cochrane Collaboration. Heterogeneity between combined studies was tested using standard chi-square test. Where statistical pooling was not appropriate or possible, the findings are summarised in narrative form. Results, A comprehensive search of relevant databases, hand searching and cross referencing found 685 articles that were assessed for relevance to the review. Eighty-five papers appeared to meet the inclusion criteria based on title and abstract, and the full paper was retrieved. Of the 85 full papers reviewed, 40 were accepted for inclusion, three were systematic reviews, three were meta-analysis, and the remaining 34 were randomised controlled trials. For the randomised controlled trials that were able to be included in a meta-analysis, standardised mean differences or weighted mean differences and their 95% confidence intervals were calculated for each. Results from comparable groups of studies were pooled in statistical meta-analysis using Review Manager Software and heterogeneity between combined studies was assessed by using the chi-square test. Where statistical pooling was not appropriate or possible, the findings are summarised in narrative form. The results are discussed in two main sections. Firstly it was possible to assess the effectiveness of different types of caregiver interventions on the outcome categories of depression, health, subjective well-being, self-efficacy and burden. Secondly, results are reported by main outcome category. For each of these sections, meta-analysis was conducted where it was possible; otherwise, a narrative summary describes the findings. Effectiveness of intervention type, Four categories of intervention were included in the review , psycho-educational, support, multi-component and other. Psycho-educational Thirteen studies used psycho-educational interventions, and all but one showed positive results across a range of outcomes. Eight studies were entered in a meta-analysis. No significant impact of psycho-educational interventions was found for the outcome categories of subjective well-being, self-efficacy or health. However, small but significant results were found for the categories of depression and burden. Support Seven studies discussed support only interventions and two of these showed significant results. These two studies were suitable for meta-analysis and demonstrated a small but significant improvement on caregiver burden. Multi-component Twelve of the studies report multi-component interventions and 10 of these report significant outcomes across a broad range of outcome measures including self-efficacy, depression, subjective well-being and burden. Unfortunately because of the heterogeneity of study designs and outcome measures, no meta-analysis was possible. Other interventions Other interventions included the use of exercise or nutrition which resulted in improvements in psychological distress and health benefits. Case management and a computer aided support intervention provided mixed results. One cognitive behavioural therapy study reported a reduction in anxiety and positive impacts on patient behaviour. Effectiveness of interventions using specific outcome categories, In addition to analysis by type of intervention it was possible to analyse results based on some outcome categories that were used across the studies. In particular the impact of interventions on caregiver depression was available for meta-analysis from eight studies. This indicated that multi-component and psycho-educational interventions showed a small but significant positive effect on caregiver depression. Five studies using the outcome category of caregiver burden were entered into a meta-analysis and findings indicated that there were no significant effects of any of interventions. No meta-analysis was possible for the outcome categories of health, self-efficacy or subjective well-being. Implications for practice, From this review there is evidence to support the use of well-designed psycho-educational or multi-component interventions for caregivers of people with dementia who live in the community. Factors that appear to positively contribute to effective interventions are those which: ,,Provide opportunities within the intervention for the person with dementia as well as the caregiver to be involved ,,Encourage active participation in educational interventions for caregivers ,,Offer individualised programs rather than group sessions ,,Provide information on an ongoing basis, with specific information about services and coaching regarding their new role ,,Target the care recipient particularly by reduction in behaviours Factors which do not appear to have benefit in interventions are those which: ,,Simply refer caregivers to support groups ,,Only provide self help materials ,,Only offer peer support [source] Systematic review on embracing cultural diversity for developing and sustaining a healthy work environment in healthcareINTERNATIONAL JOURNAL OF EVIDENCE BASED HEALTHCARE, Issue 1 2007Alan Pearson RN, FRCN, FRCNA Abstract Objectives, The objective of this review was to evaluate evidence on the structures and processes that support development of effective culturally competent practices and a healthy work environment. Culturally competent practices are a congruent set of workforce behaviours, management practices and institutional policies within a practice setting resulting in an organisational environment that is inclusive of cultural and other forms of diversity. Inclusion criteria, This review included quantitative and qualitative evidence, with a particular emphasis on identifying systematic reviews and randomised controlled trials. For quantitative evidence, other controlled, and descriptive designs were also included. For qualitative evidence, all methodologies were considered. Participants were staff, patients, and systems or policies that were involved or affected by concepts of cultural competence in the nursing workforce in a healthcare environment. Types of interventions included any strategy that had a cultural competence component, which influenced the work environment, and/or patient and nursing staff in the environment. The types of outcomes of interest to this review included nursing staff outcomes, patient outcomes, organisational outcomes and systems level outcomes. Search strategy, The search sought both published and unpublished literature written in the English language. A comprehensive three-step search strategy was used, first to identify appropriate key words, second to combine all optimal key words into a comprehensive search strategy for each database and finally to review the reference lists of all included reviews and research reports. The databases searched were CINAHL, Medline, Current Contents, the Database of Abstracts of Reviews of Effectiveness, The Cochrane Library, PsycINFO, Embase, Sociological Abstracts, Econ lit, ABI/Inform, ERIC and PubMed. The search for unpublished literature used Dissertation Abstracts International. Methodological quality, Methodological quality was independently established by two reviewers, using standardised techniques from the Joanna Briggs Institute (JBI) System for the Unified Management, Assessment and Review of Information (SUMARI) package. Discussion with a third reviewer was initiated where a low level of agreement was identified for a particular paper. Following inclusion, data extraction was conducted using standardised data extraction tools from the JBI SUMARI suite for quantitative and qualitative research. Data synthesis was performed using the JBI Qualitative Assessment and Review Instrument and JBI Narrative, Opinion and Text Assessment and Review Instrument software to aggregate findings by identifying commonalities across texts. Quantitative data were presented in narrative summary, as statistical pooling was not appropriate with the included studies. Results, Of the 659 identified papers, 45 were selected for full paper retrieval, and 19 were considered to meet the inclusion criteria for this review. The results identified a number of processes that would contribute to the development of a culturally competent workforce. Appropriate and competent linguistic services, and intercultural staff training and education, were identified as key findings in this review. Conclusions, The review recommends that health provider agencies establish links with organisations that can address needs of culturally diverse groups of patients, include cultural competence in decision support systems and staff education as well as embed them in patient brochures and educational materials. The review also concluded that staff in-service programs consider the skills needed to foster a culturally competent workforce, and recruitment strategies that also explicitly address this need. [source] International liquidity swaps: is the Chiang Mai Initiative pooling reserves efficiently?INTERNATIONAL JOURNAL OF FINANCE & ECONOMICS, Issue 4 2008E. Kohlscheen Abstract We analyse the network of bilateral liquidity swaps (BSAs) among the ASEAN+3 countries. We find that the network has taken the correlation of capital flows in the region into account, in the sense that countries with lower correlation of reserve growth have engaged in larger BSAs. All else equal, a decimal point increase in the correlation of international reserve growth decreases the size of a bilateral swap agreement between 18% and 27%. Moreover, we find that the approximately $ 60,bn of BSAs have had a limited impact, if any, on government bond spreads so far. Finally, we identify potential gains from inter-regional BSAs. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||||||||||||||