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Alternative Procedure (alternative + procedure)
Selected AbstractsEarly and Midterm Results of an Alternative Procedure to Homografts in Primary Repair of Truncus Arteriosus CommunisCONGENITAL HEART DISEASE, Issue 3 2010Pedro Curi-Curi MD ABSTRACT Background., Repair of truncus arteriosus communis (TAC) in the neonatal and early infant period has become a standard practice. We report our experience on primary repair of TAC with a bovine pericardial-valved woven Dacron conduit as an alternative procedure to homografts, with a focus on early and midterm results. Methods., From January 2001 to December 2007, 15 patients with mean age 1.5 years (range 3 months to 8 years), underwent primary repair of simple TAC. Cases with cardiogenic shock, complex-associated cardiac lesions, or adverse anatomy of the truncal valve were excluded. The Collett and Edwards anatomical type classification of TAC was as follows: type I, 13 (87%); and type II, 2 (13%). Right ventricular outflow tract was reconstructed in all the cases with a bovine pericardial-valved woven Dacron conduit. Results., Overall mortality was 6.6% (1 death due to severe pulmonary hypertension). At a mean follow-up of 31 months (range 6,51), there were no deaths (5-year actuarial survival 93.4%). Out of the 14 midterm survivors, three developed stenosis of the pericardial-valved woven Dacron conduit, but only one underwent interventional procedure including percutaneous balloon dilation with stenting for associated left pulmonary artery hypoplasia. The rate of patients with no surgical or percutaneous reinterventions performed because of obstruction of the right ventricular outflow tract reconstruction in the midterm (5 years) was 86%. Conclusions., Truncus arteriosus communis repair with a bovine pericardial-valved woven Dacron conduit can be performed with a very low perioperative mortality and satisfactory midterm morbidity, favorably compared with that reported for the use of homografts. Interventional cardiac catheterization may delay the time of reoperation for inevitable conduit replacement due to stenosis. [source] An Alternative Procedure for Fabricating a Hollow Interim Obturator for a Partial Maxillectomy PatientJOURNAL OF PROSTHODONTICS, Issue 3 2009Hiroshi Shimizu DDS Abstract A technique is described for fabricating an interim obturator for a partial maxillectomy patient. This technique enables the immediate and easy chairside fabrication of a lightweight hollow-type interim obturator when a preoperative cast is not available. After a master cast is formed, two duplicate casts are made from the master cast. One portion of the obturator is fabricated on a duplicate cast with a corrected defect, and the other portion of the prosthetic base is made on the second duplicate cast with a corrected alveolar ridge. These two portions are connected and adjusted in the patient's oral cavity. This technique is beneficial because it helps patients maintain good esthetics and their ability to speak, swallow, and chew just after surgery. [source] Assessing Goodness of Fit of Item Response Theory Models: A Comparison of Traditional and Alternative ProceduresJOURNAL OF EDUCATIONAL MEASUREMENT, Issue 4 2003Clement A. Stone Testing the goodness of fit of item response theory (IRT) models is relevant to validating IRT models, and new procedures have been proposed. These alternatives compare observed and expected response frequencies conditional on observed total scores, and use posterior probabilities for responses across , levels rather than cross-classifying examinees using point estimates of , and score responses. This research compared these alternatives with regard to their methods, properties (Type 1 error rates and empirical power), available research, and practical issues (computational demands, treatment of missing data, effects of sample size and sparse data, and available computer programs). Different advantages and disadvantages related to these characteristics are discussed. A simulation study provided additional information about empirical power and Type 1 error rates. [source] The dependence of the electrophoretic mobility of small organic ions on ionic strength and complex formationELECTROPHORESIS, Issue 5 2010Stuart A. Allison Abstract The ionic strength dependence of the electrophoretic mobility of small organic anions with valencies up to ,3 is investigated in this study. Provided the anions are not too aspherical, it is argued that shape and charge distribution have little influence on mobility. To a good approximation, the electrophoretic mobility of a small particle should be equal to that of a model sphere with the same hydrodynamic radius and same net charge. For small ions, the relaxation effect (distortion of the ion atmosphere from equilibrium due to external electric and flow fields) is significant even for monovalent ions. Alternative procedures of accounting for the relaxation effect are examined. In order to account for the ionic strength dependence of a specific set of nonaromatic and aromatic anions in aqueous solution, it is necessary to include complex formation between the anion with species in the BGE. A number of possible complexes are considered. When the BGE is Tris-acetate, the most important of these involves the complex formed between anion and Tris, the principle cation in the BGE. When the BGE is sodium borate, an anion,anion (borate) complex appears to be important, at least when the organic anion is monovalent. An algorithm is developed to analyze the ionic strength dependence of the electrophoretic mobility. This algorithm is applied to two sets of organic anions from two independent research groups. [source] Multidimensional analysis of fishery production systems in the state of Pernambuco, BrazilJOURNAL OF APPLIED ICHTHYOLOGY, Issue 3 2009R. P. Lessa Summary A total of 17 fishery systems covering gillnets, traps and seines targeting fish and crustaceans as well as hand-collected mussels in the state of Pernambuco (Brazil) were compared and analyzed in the present study using the RAPFISH method and 57 attributes to qualify five evaluation dimensions: economic, social, ecological, technological and management. The aim was to determine the sustainability of each field from the fishery (i.e. stocks) and social standpoint (i.e. fishermen). With regard to sustainability, it was generally apparent that the fisheries analyzed are far from any ideal that would permit long-term exploitation, but are nonetheless also distant from the extremes of non-sustainability in the environments investigated. The low degree of organization demonstrated in most fisheries of Pernambuco and the low level of schooling among the fishermen contribute toward maintaining the status quo, with an increase in situations of conflict and a lack of valorization regarding the activities. The shrimp system is the least sustainable, mainly due to its environmental impact; however, this is compensated by the relatively higher quality of living provided stakeholders through its exploitation. The evaluation dimensions showed the most sustainable system in Pernambuco to be the stationary ,uncovered pound net', followed by the line system. Alternative procedures for integrated fishery management, such as an increase in statistical data, coastal zoning to limit shrimp farms and establishing protected areas are proposed and discussed. Such procedures may contribute toward the formulation of public policies for the fishery industry of the state, which is essentially made up of artisanal fisheries with low yields and exercised by the 11 926 fishermen affiliated with coastal fishing colonies. [source] Early and Midterm Results of an Alternative Procedure to Homografts in Primary Repair of Truncus Arteriosus CommunisCONGENITAL HEART DISEASE, Issue 3 2010Pedro Curi-Curi MD ABSTRACT Background., Repair of truncus arteriosus communis (TAC) in the neonatal and early infant period has become a standard practice. We report our experience on primary repair of TAC with a bovine pericardial-valved woven Dacron conduit as an alternative procedure to homografts, with a focus on early and midterm results. Methods., From January 2001 to December 2007, 15 patients with mean age 1.5 years (range 3 months to 8 years), underwent primary repair of simple TAC. Cases with cardiogenic shock, complex-associated cardiac lesions, or adverse anatomy of the truncal valve were excluded. The Collett and Edwards anatomical type classification of TAC was as follows: type I, 13 (87%); and type II, 2 (13%). Right ventricular outflow tract was reconstructed in all the cases with a bovine pericardial-valved woven Dacron conduit. Results., Overall mortality was 6.6% (1 death due to severe pulmonary hypertension). At a mean follow-up of 31 months (range 6,51), there were no deaths (5-year actuarial survival 93.4%). Out of the 14 midterm survivors, three developed stenosis of the pericardial-valved woven Dacron conduit, but only one underwent interventional procedure including percutaneous balloon dilation with stenting for associated left pulmonary artery hypoplasia. The rate of patients with no surgical or percutaneous reinterventions performed because of obstruction of the right ventricular outflow tract reconstruction in the midterm (5 years) was 86%. Conclusions., Truncus arteriosus communis repair with a bovine pericardial-valved woven Dacron conduit can be performed with a very low perioperative mortality and satisfactory midterm morbidity, favorably compared with that reported for the use of homografts. Interventional cardiac catheterization may delay the time of reoperation for inevitable conduit replacement due to stenosis. [source] REASSESSING NONLINEARITY IN THE URBAN DISADVANTAGE/VIOLENT CRIME RELATIONSHIP: AN EXAMPLE OF METHODOLOGICAL BIAS FROM LOG TRANSFORMATION,CRIMINOLOGY, Issue 4 2003LANCE HANNON Sociologists and criminologists have become increasingly concerned with nonlinear relationships and interaction effects. For example, some recent studies suggest that the positive relationship between neighborhood disadvantage and violent crime is nonlinear with an accelerating slope, whereas other research indicates a nonlinear decelerating slope. The present paper considers the possibility that this inconsistency in findings is partially caused by lack of attention to an important methodological concern. Specifically, we argue that researchers have not been sensitive to the ways in which logarithmic transformation of the dependent variable can bias tests for nonlinearity and statistical interaction. We illustrate this point using demographic and violent crime data for urban neighborhoods, and we propose an alternative procedure to log transformation that involves the use of weighted least-squares regression, heteroscedasticity consistent standard errors, and diagnostics for influential observations. [source] The Politics of a European Civil CodeEUROPEAN LAW JOURNAL, Issue 6 2004Martijn W. Hesselink That plan forms an important step towards a European Civil Code. In its Plan, the Commission tries to depoliticise the codification process by asking a group of academic experts to prepare what it calls a ,common frame of reference'. This paper argues that drafting a European Civil Code involves making many choices that are essentially political. It further argues that the technocratic approach which the Commission has adopted in the Action Plan effectively excludes most stakeholders from having their say during the stage when the real choices are made. Therefore, before the drafting of the CFR/ECC starts, the Commission should submit a list of policy questions regarding the main issues of European private law to the European Parliament and the other stakeholders. Such an alternative procedure would repoliticise the process. It would increase the democratic basis for a European Civil Code and thus its legitimacy. [source] Assessment Center Procedures: Cognitive Load During the Observation PhaseINTERNATIONAL JOURNAL OF SELECTION AND ASSESSMENT, Issue 4 2002Nanja J. Kolk This study explores the traditional procedure of observing assessment center exercises while taking notes vs. an alternative procedure where assessors merely observe and postpone note-taking until immediately after the exercise. The first procedure is considered to be cognitively demanding due to the requirement of simultaneous note-taking and observing. Also, dual task processing (concurrent observing and note-taking) is considered to be especially demanding for assessors without rating experience. The procedures are evaluated using a 2 × 2 design (with note-taking/without note-taking × experienced/inexperienced). Some 121 experienced and inexperienced assessors rated videotaped candidates, observing either with or without taking notes. Results showed that experienced assessors yield significantly higher differential accuracy than inexperienced assessors. We did not find an effect of observation procedure on accuracy, interrater reliability or halo. Implications for future research are described. [source] Critical analysis of potential body temperature confounders on neurochemical endpoints caused by direct dosing and maternal separation in neonatal mice: a study of bioallethrin and deltamethrin interactions with temperature on brain muscarinic receptorsJOURNAL OF APPLIED TOXICOLOGY, Issue 1 2003Jürgen Pauluhn Abstract The present investigation was conducted to understand better possible confounding factors caused by direct dosing of neonatal mice during the pre-weaning developmental period. By direct dosing, pups might encounter thermal challenges when temporarily removed from their ,natural habitat'. Typically, this leads to a cold environment and food deprivation (impaired lactation) and modulation of the toxic potency of the substance administered. Growth retardation as a consequence of such behavioural changes in pups makes it increasingly difficult to differentiate specific from non-specific mechanisms. Neonatal NMRI mice were dosed daily by gavage (0.7 mg kg,1 body wt.) from postnatal day (PND) 10,16 with S -bioallethrin, deltamethrin or the vehicle. Then the pups, including their non-treated foster dams, were subjected temporarily for 6 h day to a hypo-, normo- or hyperthermic environment, which was followed by normal housing. The measured temperatures in the environmental chambers were ca. 21, 25 and 30°C, respectively. Thus, temperatures in the hypo- and normothermic groups are comparable to the temperatures commonly present in testing laboratories, whereas the hyperthermic condition is that temperature typically present in the ,natural habitat' of pups. A deviation from the normal behaviour of both pups and dams was observed in the hypo- and normothermic groups. In these groups the rectal temperatures of pups were markedly decreased, especially in the early phase of the study (PND 10,12). Neonates that received either test substance displayed changes in body weights and brain weights at terminal sacrifice (PND 17) when subjected temporarily to a non-physiological environment. An enormous influence of environmental temperature on the density of muscarinic receptors in the crude synaptosomal fraction of the cerebral cortex was ascertained. In summary, these results demonstrate that the direct dosing of thermolabile neonatal mice by gavage is subject to significant artefacts that render the interpretation of findings from such studies difficult. It appears that if direct dosing of neonatal pups is mandated, and inhalation is a relevant route of exposure, the combined inhalation exposure of dams with their litters is an alternative procedure that does not cause disruption of the ,natural habitat' of pups. However, owing to their higher ventilation, under such conditions the pups may receive dosages at least double those of the dams. Copyright © 2003 John Wiley & Sons, Ltd. [source] Fabrication of Direct Fiber-Reinforced Posts: A Structural Design ConceptJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 4 2001DOUGLAS A. TERRY DDS ABSTRACT As the clinician continues the quest for optimal functional and esthetic success of a tooth-restorative complex, the current selection of restorative materials and techniques may prove overwhelming. Although no single system provides the ideal restorative solution for every clinical circumstance, understanding of general design criteria and the components for the various post and core systems available allow the clinician to appropriately select the method and materials compatible with the existing tooth structure and desired result. This article provides a discussion of the various post and core systems, the methods and materials inherent in these systems, and general design principles. Using that basic information and clinical experience, the authors offer an alternative procedure for the rehabilitation of the intraradicular anatomy of the post-endodontic channel with a direct composite resin,the fiber-reinforced post and core system. CLINICAL SIGNIFICANCE Using improved restorative materials that simulate the physical properties and other characteristics of natural teeth in combination with the proper design principles, the clinician can develop a tooth-restorative complex with optimal functional and esthetic results. [source] Accuracy of the Calibration Curve Method for Absorbed Dose Assessment in Irradiated Refrigerated Chicken BoneJOURNAL OF FOOD SCIENCE, Issue 1 2001A.A. Basfar ABSTRACT: The influence of the decay of the radiation induced free radicals on electron spin resonance (ESR) bone dosimetry was studied. The absorbed doses in irradiated bone are usually assessed by applying correction factors for decay. An alternative procedure is presented in which the ESR readout was performed only when the ESR signal had reached good stability for the bone samples used to establish the calibration curves and also on bones for which absorbed dose assessment was to be made. The results of the evaluated doses obtained by using this approach were the same as the ones obtained by using corrections for the decay of ESR signals. [source] On the use of large time steps with ELLAM for transport with kinetic reactions over heterogeneous domainsAICHE JOURNAL, Issue 5 2009Marwan Fahs Abstract An Eulerian Lagrangian localized adjoint method (ELLAM) is considered for the resolution of advection-dominated transport problems in porous media. Contrary to standard Eulerian methods, ELLAM can use large time steps because the advection term is approximated accurately without any CFL restriction. However, it is shown in this article that special care must be taken for the approximation of the dispersive and reactive terms when large time steps are used over heterogeneous domains. An alternative procedure is proposed. It is based on an equivalent dispersion coefficient or an equivalent reaction rate when different zones are encountered during the tracking. Numerical experiments are performed with variable dispersion or variable reaction rates over space (including nonlinearity). When classical ELLAM require numerous time steps to handle heterogeneity, the alternative procedure is shown to perform with the same accuracy in a single time step. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Extraction of pure lycopene from industrial tomato by-products in water using a new high-pressure processJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2008Daniele Naviglio Abstract BACKGROUND: Lycopene, a precursor of ,-carotene with a well-known antioxidant activity, contained in many natural products such as tomato (Lycopersicon esculentum Mill.), watermelon, red pepper and papaya, is usually recovered from natural vegetal sources using organic solvents and a purification step. In this paper an innovative process for the extraction of pure lycopene from tomato waste in water that uses the Naviglio® extractor and water as extracting phase is presented. RESULTS: Lycopene was obtained in the all- trans form at a very high grade of purity, not less than 98% (w/w), with an average recovery of 14% (w/w). The availability of high-purity trans -lycopene allowed measurement of the molar absorption coefficient. An alternative procedure for high-performance liquid chromatographic analysis using a phenyl-hexyl silicone phase as inverse phase and a linear gradient in water and acetonitrile is also described. CONCLUSIONS: The use of water as extracting phase considerably reduces the cost of the entire process when compared with the commonly used solvent-based procedure or with the newer supercritical extraction process of lycopene from tomato waste. Lycopene, not soluble in water, was recovered in a quasi-crystalline solid form and purified by solid-phase extraction using a small amount of organic solvent. Copyright © 2008 Society of Chemical Industry This article was published online on September 15, 2008. Errors in Figures 2 - 4 were subsequently identified. The publishers wish to apologise for these errors. This notice is included in the online and print versions to indicate that both have been corrected [September 19, 2008] [source] A new type of magnification system in free microvascular tissue transfer: Varioscope M5MICROSURGERY, Issue 6 2007Ph.D., Stefano Chiummariello M.D. Free microvascular tissue transfers have become today a key instrument for the surgical treatment of wide loss of tissue. These procedures can provide definitive treatment in a single operation but they are expensive and require specialized practitioners. The operating microscope traditionally has provided this requirement; our study is focusing on the prospect of using a new visual system,Varioscope M5,in the reconstructive microsurgery field. Varioscope M5 (Life Optics, Vienna, Austria) has been employed in 21 microvascular anastomoses, where different free flaps were used in head and neck reconstruction. The necessity to operate in a different department, not provided with an operating microscope, brought along the idea of exploring an alternative procedure to classical visualization systems. Specific advantages such as reduced cost, freedom of movement, autofocus, minimal upkeep, a variable range of magnification from 2× to 9× are some of the reasons that convinced the authors to use this new type of magnification system. Increasing interest in microsurgery magnification highlights the need for further technical development in that field. We consider Varioscope M5 a future mean of anastomotic magnification in most free-tissue transfers with specific characteristics that combine the microscope and loupe philosophies. © 2007 Wiley-Liss, Inc. Microsurgery, 2007. [source] A novel visual analogue scale (VAS) device: an instrument based on the VAS designed to quantify the subjective visual experienceOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 3 2004Jonathan S. Pointer Abstract Purpose :,To evaluate a novel device intended to facilitate the direct quantification of the subjective visual experience. The design principle is based on that of the visual analogue scale (VAS) technique but obviates the need for subsequent measurement unlike the administration of the conventional paper VAS. Methods :,The visual experience of 134 normally sighted 17,40-year-olds was quantified using (in randomised sequence) a paper VAS and the novel VAS device. A notional 100-point scale was utilised in either case, and the extreme descriptive anchors for both instruments were ,dreadful' and ,perfect'. Results :,The degree of clinical agreement between the two alternative VAS techniques was very high. A small bias (mean = +0.7 VAS units: 95% confidence interval 0.3,1.2 units) towards the paper VAS was evident in these data, an outcome of no clinical significance or impediment as regards the substitution of the novel device for the conventional paper-based approach. Conclusions :,The moving of a bead along a wire is shown to be a clinically and statistically reliable alternative procedure to the pen-marking of a conventional paper VAS for the evaluation of the recent subjective visual experience, provided that the same minimum/maximum descriptive anchors are used for either instrument. The instant quantification of the VAS score afforded by the novel technique introduced here broadens the potential clinical application of this technique. [source] Mixed-effects models in psychophysiologyPSYCHOPHYSIOLOGY, Issue 1 2000Emilia Bagiella The current methodological policy in Psychophysiology stipulates that repeated-measures designs be analyzed using either multivariate analysis of variance (ANOVA) or repeated-measures ANOVA with the Greenhouse,Geisser or Huynh,Feldt correction. Both techniques lead to appropriate type I error probabilities under general assumptions about the variance-covariance matrix of the data. This report introduces mixed-effects models as an alternative procedure for the analysis of repeated-measures data in Psychophysiology. Mixed-effects models have many advantages over the traditional methods: They handle missing data more effectively and are more efficient, parsimonious, and flexible. We described mixed-effects modeling and illustrated its applicability with a simple example. [source] Cassette-accelerated rapid rat screen: a systematic procedure for the dosing and liquid chromatography/atmospheric pressure ionization tandem mass spectrometric analysis of new chemical entities as part of new drug discoveryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 5 2001Walter A. Korfmacher This report addresses the continuing need for increased throughput in the evaluation of new chemical entities (NCEs) in terms of their pharmacokinetic (PK) parameters by describing an alternative procedure for increasing the throughput of the in vivo screening of NCEs in the oral rat PK model. The new approach is called ,cassette-accelerated rapid rat screen' (CARRS). In this assay, NCEs are dosed individually (n,=,2 rats/compound) in batches of six compounds per set. The assay makes use of a semi-automated protein precipitation procedure for sample preparation in a 96-well plate format. The liquid chromatography/atmospheric pressure ionization tandem mass spectrometry (LC/API-MS/MS) assay is also streamlined by analyzing the samples as ,cassettes of six'. Using this new approach, a threefold increase in throughput was achieved over the previously reported ,rapid rat screen'. Copyright © 2001 John Wiley & Sons, Ltd. [source] Do not adjust coefficients in Shapley value regressionAPPLIED STOCHASTIC MODELS IN BUSINESS AND INDUSTRY, Issue 2 2010Ulrike Grömping Abstract Shapley value regression consists of assessing relative importance and accordingly adjusting regression coefficients. It is argued that adjustment of coefficients is unnecessary and even misleading for practically relevant situations. Examples are given, and an alternative procedure is proposed for situations for which the coefficients are requested to have a certain sign. Copyright © 2009 John Wiley & Sons, Ltd. [source] Use of Bakri balloon in post-partum haemorrhage: A series of 15 casesAUSTRALIAN AND NEW ZEALAND JOURNAL OF OBSTETRICS AND GYNAECOLOGY, Issue 2 2009Srisailesh VITTHALA Background: Post-partum haemorrhage (PPH) is a major complication of delivery. Hysterectomy is commonly performed when medical treatment of PPH fails. We assessed the effectiveness of Bakri balloon tamponade, a non-surgical technique in the management of PPH. Aim(s): Our objective is to report our experience in the use of Bakri balloon in treating PPH. Method: A retrospective study of 15 patients who underwent Bakri balloon insertion after unsuccessful medical management of PPH. Results: Fifteen cases of PPH were managed with Bakri balloon insertion. It was effective in all cases of PPH after vaginal delivery and in four cases of caesarean section; the overall effectiveness was 80%. Conclusion: Insertion of Bakri balloon is a simple alternative procedure in the management of PPH. It should be consider before any further surgical intervention including hysterectomy. Junior doctors and midwives can effectively apply it. It can be used during transfer or while waiting for a surgical procedure to reduce blood loss. [source] Measuring inequality in self-reported health,discussion of a recently suggested approach using Finnish dataHEALTH ECONOMICS, Issue 7 2004Jorgen Lauridsen Health surveys often include a general question on self-assessed health (SAH), usually measured on an ordinal scale with three to five response categories, from ,very poor' or ,poor' to ,very good' or ,excellent'. This paper assesses the scaling of responses on the SAH question. It compares alternative procedures designed to impose cardinality on the ordinal responses. These include OLS, ordered probit and interval regression approaches. The cardinal measures of health are used to compute and decompose concentration indices for income-related inequality in health. Results are provided using Finnish data on 15D and the SAH questions. Further evidence emerges for the internal validity of a method used in a pioneering study by van Doorslaer and Jones which was based on Canadian data on the McMaster Health Utility Index Mark III (HUI) and SAH. The study validates the conclusions drawn by van Doorslaer and Jones. It confirms that the interval regression approach is superior to OLS and ordered probit regression in assessing health inequality. However, regarding the choice of scaling instrument, it is concluded that the scaling of SAH categories and, consequently, the measured degree of inequality, are sensitive to characteristics of the chosen scaling instrument. Copyright © 2003 John Wiley & Sons, Ltd. [source] On boundary conditions of the characteristic based split (CBS) algorithm for fluid dynamicsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 4 2002P. NithiarasuArticle first published online: 12 MAR 200 Abstract This paper discusses alternative procedures which can be used in the application of boundary conditions for the CBS algorithm. Attention is focused on the problem of application of prescribed velocity and traction conditions. The paper is illustrated with some incompressible flow problems. Although previously logical and correct boundary condition specifications were introduced, the procedures outlined in this paper simplify calculations and generally make it more accurate. Copyright © 2002 John Wiley & Sons, Ltd. [source] An assessment of hydraulic design of trickle laterals considering effect of minor losses,IRRIGATION AND DRAINAGE, Issue 4 2007Gürol Y canalisations d'eau; canalisations tertiaires; conception hydraulique; analyse; perte de charge Abstract The accurate design of trickle irrigation laterals needs to determine the total energy losses that includes the pipe friction losses along the lateral line and the local pressure losses, sometimes called minor losses, due to the protrusion of emitter barbs into the flow. Evaluation of energy losses is usually carried out by assuming the hypothesis that minor losses can be neglected, even if previous experimental studies indicated that minor losses can become a significant percentage of total energy losses as a consequence of the high number of emitters installed along the lateral line. In this study, a simple analytical procedure is presented to evaluate the effect of minor losses which is characterized by a coefficient ,i, expressing the amount of minor head losses as a fraction of the kinetic head, on trickle lateral design. According to both the design cases of without and including minor losses, the dimensionless design curves were developed for both the various lateral diameters and lengths. The results of two practical examples for designing either the diameter or the length indicated that, in some design cases, neglecting minor losses may lead to erroneous designs of the lateral diameter and length. This method is simple and easily adaptable to solve lateral hydraulic problems but sufficiently precise in comparison with the alternative procedures. The proposed equations are useful when applied for design and evaluation purposes and offer a practical field solution for laterals used in irrigation systems. Copyright © 2007 John Wiley & Sons, Ltd. La conception précise des canalisations tertiaires dans un système d'irrigation au goutte à goutte doit déterminer le total des pertes de charge qui viennent du frottement dans la canalisation elle-même mais aussi des pertes locales, parfois appelées pertes mineures, dues à la protubérance de barbes au niveau des goutteurs. Cette évaluation est normalement réalisée en considérant comme négligeables les pertes mineures, même si des études expérimentales ont montré que ces pertes mineures pouvaient constituer un pourcentage significatif de la perte de charge totale du fait du grand nombre de goutteurs installés le long de la canalisation tertiaire. Dans cette étude, une procédure analytique simple est proposée pour évaluer l'effet des pertes mineures sur la conception des canalisations tertiaires grâce à un coefficient ,i, exprimant le montant de ces pertes en une fraction de la charge cinétique. En fonction des diverses options de conception prenant ou non en compte les pertes mineures, des courbes de conception non dimensionnelles ont été tracées pour les diamètres et les longueurs des canalisations. Les résultats de deux exemples concrets montrent que, dans certains cas de conception, le fait de négliger les pertes mineures peut conduire à des conceptions de diamètre et de longueur erronées. Cette méthode est simple et facilement adaptable à la résolution de problèmes hydrauliques au niveau des tertiaires mais suffisamment précise par rapport des méthodes alternatives. Les équations proposées sont utiles pour la conception et l'évaluation et offrent une solution de terrain concrète pour les canalisations tertiaires utilisées dans des systèmes d'irrigation (au goutte à goutte). Copyright © 2007 John Wiley & Sons, Ltd. [source] Bootstrap predictive inference for ARIMA processesJOURNAL OF TIME SERIES ANALYSIS, Issue 4 2004Lorenzo Pascual Abstract., In this study, we propose a new bootstrap strategy to obtain prediction intervals for autoregressive integrated moving-average processes. Its main advantage over other bootstrap methods previously proposed for autoregressive integrated processes is that variability due to parameter estimation can be incorporated into prediction intervals without requiring the backward representation of the process. Consequently, the procedure is very flexible and can be extended to processes even if their backward representation is not available. Furthermore, its implementation is very simple. The asymptotic properties of the bootstrap prediction densities are obtained. Extensive finite-sample Monte Carlo experiments are carried out to compare the performance of the proposed strategy vs. alternative procedures. The behaviour of our proposal equals or outperforms the alternatives in most of the cases. Furthermore, our bootstrap strategy is also applied for the first time to obtain the prediction density of processes with moving-average components. [source] Versatility of vertical rectus abdominis musculocutaneous flapsMICROSURGERY, Issue 5 2006Markus V. Küntscher M.D., Ph.D. The purpose of the study was to demonstrate a variety of indications for the vertical rectus abdominis musculocutaneous (VRAM) flap with respect to donor-site morbidity and alternative procedures. Fifteen VRAM flaps were performed in 15 patients during a 4-year period. The average age of patients was 58 years (range, 34,76 years). Inferiorly based VRAM flaps were used for defect coverage after tumor resection and for penile reconstruction in 7 cases. Superiorly based VRAM flaps were performed in 7 cases for reconstruction of osteocutaneous defects following sternal osteomyelitis and tumor resection. Arterial and venous "supercharging" was necessary in one case. One free VRAM flap was performed in a patient suffering from an osteocutaneous defect after resection of a malignant melanoma metastasis with infiltration of the brain and skull. The reconstructive goals were achieved in all cases using VRAM flap procedures. No total flap loss occurred. Minor complications as well as abdominal wall bulging and hernias were observed in four cases. The pedicled VRAM flap provides a reliable tool for coverage of large soft-tissue defects of the chest wall, groin, hip, and perineum even in a high-risk population, in which a safe and fast forward flap procedure is the primary reconstructive goal. Arterial and/or venous supercharging may be necessary, particularly in superiorly based VRAM flaps. An inferiorly based VRAM flap is a reliable tool for phalloplasty under special circumstances. The indication for free VRAM flaps is given in rare clinical situations. Stabilization of the donor site using artificial mesh is highly recommended. © 2006 Wiley-Liss, Inc. Microsurgery, 2006. [source] Imputation Strategies for Missing Continuous Outcomes in Cluster Randomized TrialsBIOMETRICAL JOURNAL, Issue 3 2008Monica Taljaard Abstract In cluster randomized trials, intact social units such as schools, worksites or medical practices , rather than individuals themselves , are randomly allocated to intervention and control conditions, while the outcomes of interest are then observed on individuals within each cluster. Such trials are becoming increasingly common in the fields of health promotion and health services research. Attrition is a common occurrence in randomized trials, and a standard approach for dealing with the resulting missing values is imputation. We consider imputation strategies for missing continuous outcomes, focusing on trials with a completely randomized design in which fixed cohorts from each cluster are enrolled prior to random assignment. We compare five different imputation strategies with respect to Type I and Type II error rates of the adjusted two-sample t -test for the intervention effect. Cluster mean imputation is compared with multiple imputation, using either within-cluster data or data pooled across clusters in each intervention group. In the case of pooling across clusters, we distinguish between standard multiple imputation procedures which do not account for intracluster correlation and a specialized procedure which does account for intracluster correlation but is not yet available in standard statistical software packages. A simulation study is used to evaluate the influence of cluster size, number of clusters, degree of intracluster correlation, and variability among cluster follow-up rates. We show that cluster mean imputation yields valid inferences and given its simplicity, may be an attractive option in some large community intervention trials which are subject to individual-level attrition only; however, it may yield less powerful inferences than alternative procedures which pool across clusters especially when the cluster sizes are small and cluster follow-up rates are highly variable. When pooling across clusters, the imputation procedure should generally take intracluster correlation into account to obtain valid inferences; however, as long as the intracluster correlation coefficient is small, we show that standard multiple imputation procedures may yield acceptable type I error rates; moreover, these procedures may yield more powerful inferences than a specialized procedure, especially when the number of available clusters is small. Within-cluster multiple imputation is shown to be the least powerful among the procedures considered. 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