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Optimal
Kinds of Optimal Terms modified by Optimal Selected AbstractsOPTIMAL AND ADAPTIVE SEMI-PARAMETRIC NARROWBAND AND BROADBAND AND MAXIMUM LIKELIHOOD ESTIMATION OF THE LONG-MEMORY PARAMETER FOR REAL EXCHANGE RATES,THE MANCHESTER SCHOOL, Issue 2 2005SAEED HERAVI The nature of the time series properties of real exchange rates remains a contentious issue primarily because of the implications for purchasing power parity. In particular are real exchange rates best characterized as stationary and non-persistent; nonstationary but non-persistent; or nonstationary and persistent? Most assessments of this issue use the I(0)/I(1) paradigm, which only allows the first and last of these options. In contrast, in the I(d) paradigm, d fractional, all three are possible, with the crucial parameter d determining the long-run properties of the process. This study includes estimation of d by three methods of semi-parametric estimation in the frequency domain, using both local and global (Fourier) frequency estimation, and maximum likelihood estimation of ARFIMA models in the time domain. We give a transparent assessment of the key selection parameters in each method, particularly estimation of the truncation parameters for the semi-parametric methods. Two other important developments are also included. We implement Tanaka's locally best invariant parametric tests based on maximum likelihood estimation of the long-memory parameter and include a recent extension of the Dickey,Fuller approach, referred to as fractional Dickey,Fuller (FD-F), to fractionally integrated series, which allows a much wider range of generating processes under the alternative hypothesis. With this more general approach, we find very little evidence of stationarity for 10 real exchange rates for developed countries and some very limited evidence of nonstationarity but non-persistence, and none of the FD-F tests leads to rejection of the null of a unit root. [source] Optimal Left Ventricular Lead Position Predicts Reverse Remodeling and Survival After Cardiac Resynchronization TherapyCONGESTIVE HEART FAILURE, Issue 2 2009David Tepper MD Background., A nonoptimal LV pacing lead position may be a potential cause for nonresponse to CRT. Methods., The site of latest mechanical activation was determined by speckle tracking radial strain analysis and related to the LV lead position on chest x-ray in 244 CRT candidates. Echocardiographic evaluation was performed after 6 months. Long-term follow-up included all-cause mortality and hospitalizations for heart failure. Results., Significant LV reverse remodeling (reduction in LV end-systolic volume from 189±83 mL to 134±71 mL, P<.001) was noted in the group of patients with a concordant LV lead position (n=153, 63%), whereas patients with a discordant lead position showed no significant improvements. In addition, during long-term follow-up (32±16 months), less events (combined for heart failure hospitalizations and death) were reported in patients with a concordant LV lead position. Moreover, a concordant LV lead position appeared to be an independent predictor of hospitalization-free survival after long-term CRT (hazard ratio: 0.22, P=.004). Conclusions., Pacing at the site of latest mechanical activation, as determined by speckle tracking radial strain analysis, resulted in superior echocardiographic response after 6 months of CRT and better prognosis during long-term follow-up. [source] Optimal design of supplemental viscous dampers for irregular shear-frames in the presence of yieldingEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 8 2005Oren Lavan Abstract A methodology for the optimal design of supplemental viscous dampers for regular as well as irregular yielding shear-frames is presented. It addresses the problem of minimizing the added damping subject to a constraint on an energy-based global damage index (GDI) for an ensemble of realistic ground motion records. The applicability of the methodology for irregular structures is achieved by choosing an appropriate GDI. For a particular choice of the parameters comprising the GDI, a design for the elastic behavior of the frame or equal damage for all stories is achieved. The use of a gradient-based optimization algorithm for the solution of the optimization problem is enabled by first deriving an expression for the gradient of the constraint. The optimization process is started for one ,active' ground motion record which is efficiently selected from the given ensemble. If the resulting optimal design fails to satisfy the constraints for other records from the original ensemble, additional ground motions (loading conditions) are added one by one to the ,active' set until the optimum is reached. Two examples for the optimal designs of supplemental dampers are given: a 2-story shear frame with varying strength distribution and a 10-story shear frame. The 2-story shear frame is designed for one given ground motion whereas the 10-story frame is designed for an ensemble of twenty ground motions. Copyright © 2005 John Wiley & Sons, Ltd. [source] Optimal design of added viscoelastic dampers and supporting bracesEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 4 2004Ji-Hun Park Abstract This paper presents a simultaneous optimization procedure for both viscoelastic dampers (VEDs) and supporting braces installed in a structure. The effect of supporting braces on the control efficiency of VEDs is also investigated. To apply a general gradient-based optimization algorithm, closed-form expressions for the gradients of objective function and constraints are derived. Also, the constraint on the dynamic behavior of a structure is embedded in the gradient computation procedure to reduce the number of variables in the optimization. From numerical analysis of an example structure, it was found that when sufficient stiffness cannot be provided for the supporting braces, the flexibility of the brace should be taken into account in the design of the VED to achieve the desired performance of the structure. It was also observed that, as a result of the proposed optimization process, the size of the supporting brace could be reduced while the additional VED size (to compensate for the loss of the control effect) was insignificant. Copyright © 2003 John Wiley & Sons, Ltd. [source] Three Options Are Optimal for Multiple-Choice Items: A Meta-Analysis of 80 Years of ResearchEDUCATIONAL MEASUREMENT: ISSUES AND PRACTICE, Issue 2 2005Michael C. Rodriguez Multiple-choice items are a mainstay of achievement testing. The need to adequately cover the content domain to certify achievement proficiency by producing meaningful precise scores requires many high-quality items. More 3-option items can be administered than 4- or 5-option items per testing time while improving content coverage, without detrimental effects on psychometric quality of test scores. Researchers have endorsed 3-option items for over 80 years with empirical evidence,the results of which have been synthesized in an effort to unify this endorsement and encourage its adoption. [source] Optimal and self-tuning fusion Kalman filters for discrete-time stochastic singular systemsINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 10 2008Shu-Li Sun Abstract Based on the optimal fusion estimation algorithm weighted by scalars in the linear minimum variance sense, a distributed optimal fusion Kalman filter weighted by scalars is presented for discrete-time stochastic singular systems with multiple sensors and correlated noises. A cross-covariance matrix of filtering errors between any two sensors is derived. When the noise statistical information is unknown, a distributed identification approach is presented based on correlation functions and the weighted average method. Further, a distributed self-tuning fusion filter is given, which includes two stage fusions where the first-stage fusion is used to identify the noise covariance and the second-stage fusion is used to obtain the fusion state filter. A simulation verifies the effectiveness of the proposed algorithm. Copyright © 2008 John Wiley & Sons, Ltd. [source] Blood Pressure Goals for Hypertension Guidelines: What Is Wrong With "Optimal"?JOURNAL OF CLINICAL HYPERTENSION, Issue 12 2006Thomas D. Giles MD First page of article [source] Problem management maturity within corrective maintenanceJOURNAL OF SOFTWARE MAINTENANCE AND EVOLUTION: RESEARCH AND PRACTICE, Issue 3 2002Mira Kajko-Mattsson Abstract CM: Problem Management is a first detailed descriptive problem management process model to be utilized within corrective maintenance. It is the result of a long-term empirical study of industrial corrective maintenance processes. It has been developed at ABB and evaluated for its industrial relevance within 17 non-ABB organizations. Playing the role of a descriptive model, CM: Problem Management specifies what a problem management process should look like. It also structures it into three maturity levels, Initial, Defined, and Optimal, where each level offers a different grainedness of process visibility. In this paper, we present the CM levels of problem management process maturity within corrective maintenance and match them against the industrial state of practice. Our goal is to establish the current status of problem management maturity using CM: Problem Management as an evaluation model. Our evaluation results show that the industrial processes today suffice to attend to software problems within corrective maintenance. Very few of them, however, do learn from the past in order to prevent future problems and to improve development or maintenance processes. Copyright © 2002 John Wiley & Sons, Ltd. [source] Optimal and sub-optimal control in Dengue epidemicsOPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 2 2001Marco Antonio Leonel Caetano Abstract This work concerns the application of the optimal control theory to Dengue epidemics. The dynamics of this insect-borne disease is modelled as a set of non-linear ordinary differential equations including the effect of educational campaigns organized to motivate the population to break the reproduction cycle of the mosquitoes by avoiding the accumulation of still water in open-air recipients. The cost functional is such that it reflects a compromise between actual financial spending (in insecticides and educational campaigns) and the population health (which can be objectively measured in terms of, for instance, treatment costs and loss of productivity). The optimal control problem is solved numerically using a multiple shooting method. However, the optimal control policy is difficult to implement by the health authorities because it is not practical to adjust the investment rate continuously in time. Therefore, a suboptimal control policy is computed assuming, as the admissible set, only those controls which are piecewise constant. The performance achieved by the optimal control and the sub-optimal control policies are compared with the cases of control using only insecticides when Breteau Index is greater or equal to 5 and the case of no-control. The results show that the sub-optimal policy yields a substantial reduction in the cost, in terms of the proposed functional, and is only slightly inferior to the optimal control policy. Copyright © 2001 John Wiley & Sons, Ltd. [source] Structure,Activity Relationships through Sequencing (StARTS) Defines Optimal and Suboptimal RNA Motif Targets for Small Molecules,ANGEWANDTE CHEMIE, Issue 22 2010Pradeep Velagapudi Genau ins Schwarze: Ein kombinierter Computer- und experimenteller Ansatz identifiziert optimale (und suboptimale) RNA-Motive als Angriffsziele niedermolekularer Verbindungen mithilfe eines zweidimensionalen kombinatorischen Screenings. Die als ,Struktur-Aktivitäts-Beziehungen durch Sequenzierung" (StARTS) bezeichnete Methode nutzt Sequenzinformationen der gewählten RNA-Motive für die Bindung eines Liganden. [source] Water fluoridation, osteoporosis, fractures,recent developmentsAUSTRALIAN DENTAL JOURNAL, Issue 2 2001Lisa L. Demos Abstract Background: Optimal (1 ppm) water fluoridation is seen as the most socially equitable way to prevent dental caries, however concerns about the safety of fluoridation are periodically raised. Methods: Research on effects on bone published since the 1991 National Health and MedicalResearch Council report on water fluoridation was reviewed. Results: Thirty-three studies were identified. Adverse effects in animal feeding studies were only seen at doses much greater than those currently used in artificial water fluoridation. The majority of animal studies showed no effect or a beneficial effect of lowfluoride doses. The results of ecological studies were conflicting. One of the two cohort studies showed an increase in fracture incidence at fluoride levels four times greater than optimal water fluoridation and the other showed no effect after 20 years' optimal fluoridation. The cross-sectional studies showed a favourable effect on bone mineral density. The clinical trials predominantly showed increased bone density in several sites associated with fluoride treatment of 9,22.6mg fluoride per day for one-four years. Conclusion: These studies provide a substantial body of evidence that fluoride at up to 1ppm does not have an adverse effect on bone strength, bone mineral density or fracture incidence. [source] Do radiologists agree on the quality of computed tomography enterography?JOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 4 2009Kari Ersland Summary This study aimed to assess variation between radiologists evaluating the quality of multi-detector computed tomography enterography. For 40 consecutive examinations, three experienced radiologists independently rated the following quality variables: % length of adequately filled bowel, bowel lumen diameters, bowel wall delineation, superior mesenteric vein, and bowel wall enhancement, artefacts, and total quality. We calculated the mean difference between observers with standard deviation (SD) for continuous variables and % total agreement, exact Fleiss kappa, and P -values (McNemar's test) for categorical variables. Depending on bowel segment (duodenum distal to bulb, jejunum, ileum, terminal ileum), mean difference between observers ranged from two to 33 (SD from 11 to 32) for % length of adequately filled bowel judged subjectively, 0,2 (SD 0,3) mm for smallest bowel lumen diameter and 0,4 (SD 3,7) mm for largest bowel lumen diameter. Agreement on bowel wall delineation was 80%/kappa 0.50 in duodenum, 90%/kappa 0.57 in jejunum, 75%/kappa 0.14 in ileum and 88%/kappa 0.17 in terminal ileum, where ratings differed between observers (P < 0.04). Agreement was 65%/kappa 0.18 for bowel wall enhancement judged subjectively. For contrast enhancement measured in Hounsfield Units, mean difference between observers ranged from two to 11 (SD 12,15) in normal jejunum wall and zero to one (SD 4,5) in the superior mesenteric vein depending on observer pair. Agreement was 78%/kappa 0.12 for image artefacts. Rating of total examination quality (good/optimal versus poor/very poor) differed between observers (P < 0.01); agreement was 60%/kappa 0.41. Many subjective evaluations varied between observers. We believe that measurements of bowel lumen diameters and contrast enhancement may be preferable. [source] Preference-Based Constrained Optimization with CP-NetsCOMPUTATIONAL INTELLIGENCE, Issue 2 2004Craig Boutilier Many artificial intelligence (AI) tasks, such as product configuration, decision support, and the construction of autonomous agents, involve a process of constrained optimization, that is, optimization of behavior or choices subject to given constraints. In this paper we present an approach for constrained optimization based on a set of hard constraints and a preference ordering represented using a CP-network,a graphical model for representing qualitative preference information. This approach offers both pragmatic and computational advantages. First, it provides a convenient and intuitive tool for specifying the problem, and in particular, the decision maker's preferences. Second, it admits an algorithm for finding the most preferred feasible (Pareto-optimal) outcomes that has the following anytime property: the set of preferred feasible outcomes are enumerated without backtracking. In particular, the first feasible solution generated by this algorithm is Pareto optimal. [source] Automatic Palletizing of Concrete Pavement Blocks: An Algorithm for Near-Optimal AssemblyCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 3 2001Shraga Shoval Palletizing concrete pavement blocks is a labor-intensive task that requires high levels of workmanship, skill, and concentration. This article proposes an automatic system in which palettes with required design patterns are assembled automatically off-site and then shipped to the construction site. The efficiency of the assembly process can be improved by incorporating automatic equipment consisting of assembly heads and feeders. An algorithm was developed to determine the optimal layout of the feeders (of different blocks) around the palette and the exact assembly sequence of each layer of blocks. Experimental results show that the algorithm is near optimal and that the solutions provided by it reduce palletizing cycle time for various patterns and sizes of concrete block by 20 to 30 percent. [source] Toward portable nuclear magnetic resonance devices using atomic magnetometersCONCEPTS IN MAGNETIC RESONANCE, Issue 2 2009Dindi Yu Abstract The motivation for developing alternative detection techniques for nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) is to overcome some of the limitations associated with high-field NMR/MRI instruments. The limitations include poor portability, cryogenic requirements, and high costs. To achieve this goal, a low magnetic field is preferred. Since the sensitivity of inductive detection for conventional NMR and MRI scales linearly with the magnetic field strength, it is not optimal for low-field detection. In this contribution, we describe the concept of using atomic magnetometers as an alternative detection method. Atomic magnetometers possess an ultrahigh sensitivity that is independent of the magnetic field strength, which makes them viable for low-field detection in NMR and MRI. We first introduce the principle of atomic magnetometry and follow this with a discussion of recent progress in the field. To compare the sensitivities of atomic magnetometers of diverse sizes, we define a signal-to-noise ratio for a fixed detection volume to normalize the sensitivity with regard to the cell size. We then focus on two coupling schemes for NMR and MRI detection using atomic magnetometers. Finally, we discuss the challenges involved in implementing this alternative detection technique for NMR and MRI. © 2009 Wiley Periodicals, Inc. Concepts Magn Reson Part A 34A: 124,132, 2009. [source] GAUGE: Grid Automation and Generative Environment,CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 10 2006Francisco Hernández Abstract The Grid has proven to be a successful paradigm for distributed computing. However, constructing applications that exploit all the benefits that the Grid offers is still not optimal for both inexperienced and experienced users. Recent approaches to solving this problem employ a high-level abstract layer to ease the construction of applications for different Grid environments. These approaches help facilitate construction of Grid applications, but they are still tied to specific programming languages or platforms. A new approach is presented in this paper that uses concepts of domain-specific modeling (DSM) to build a high-level abstract layer. With this DSM-based abstract layer, the users are able to create Grid applications without knowledge of specific programming languages or being bound to specific Grid platforms. An additional benefit of DSM provides the capability to generate software artifacts for various Grid environments. This paper presents the Grid Automation and Generative Environment (GAUGE). The goal of GAUGE is to automate the generation of Grid applications to allow inexperienced users to exploit the Grid fully. At the same time, GAUGE provides an open framework in which experienced users can build upon and extend to tailor their applications to particular Grid environments or specific platforms. GAUGE employs domain-specific modeling techniques to accomplish this challenging task. Copyright © 2005 John Wiley & Sons, Ltd. [source] Combining Strategies to Select Reserves in Fragmented LandscapesCONSERVATION BIOLOGY, Issue 4 2004KRISTINA D. ROTHLEY These criteria are assumed to be reasonable surrogates for the true network objectives. Caution is warranted, however, because the relationships between the selection criteria and the reserve-network objectives may be inconsistent. Conflicts are also likely to arise because no single reserve network will be optimal with respect to multiple objectives (or selection criteria) simultaneously. Instead, reserve planners must compromise between conflicting demands. We field tested the relationships between a variety of selection criteria and the objectives of a reserve network for the sandplain natural communities on Martha's Vineyard Island, Massachusetts (U.S.A.). Selection criteria that correlated with the reserve-network objectives were used in a multi-objective integer program to identify the 10-patch reserve networks that were optimal with each objective independently and those that offered optimal tradeoffs between the reserve-network objectives. From these 10-patch networks, one can select a final reserve network that provides the preferred compromise between the objectives. Resumen:,La utilización de criterios de selección, como el tamaño de parche, para clasificar el valor de conservación de los parches de hábitat y evaluar redes de reservas alternativas es un método para identificar redes de reservas en paisajes fragmentados con datos especie-específicos limitados,. Se asume que estos criterios son sustitutos razonables de los verdaderos objetivos de la red. Sin embargo, se requiere cuidado porque las relaciones entre los criterios de selección y los objetivos de la red de reservas pueden ser inconsistentes. Es probable que surjan conflictos porque ninguna red de reservas seráóptima con respecto a objetivos (o criterios de selección) múltiples simultáneamente. Más bien, los planificadores de reservas deben transigir entre demandas conflictivas. Probamos las relaciones entre una variedad de criterios de selección y los objetivos de una red de reservas para comunidades arenícolas naturales en la Isla Martha's Vineyard, Massachussets (E.U.A.). Los criterios de selección que se correlacionaron con los objetivos de la red de reservas fueron utilizados en un programa multi-objetivo integral para identificar las 10 redes de reservas de fragmentos óptimas con cada objetivo independientemente y las que ofrecían compensaciones óptimas entre los objetivos de la red de reservas. De estas 10 redes de reservas de fragmentos, se puede seleccionar una red de reservas final que proporcione el compromiso preferido entre los objetivos. [source] Optimal conservation planning for migratory animals: integrating demographic information across seasonsCONSERVATION LETTERS, Issue 3 2010Justin Sheehy Abstract Conservation strategies for migratory animals are typically based on ad-hoc or simple ranking methods and focus on a single period of the annual cycle. We use a density-dependent population model to examine one-time land purchase strategies for a migratory population with a breeding and wintering grounds. Under equal rates of habitat loss, we show that it is optimal to invest more, but never solely, in the habitat with the higher density dependence to habitat cost ratio. When there are two habitats that vary in quality within a season, the best strategy is to invest only in one habitat. Whether to purchase high- or low-quality habitat depends on the general life history of the species and the ratio of habitat quality to habitat cost. When carry-over effects are incorporated, it is almost always optimal to invest in high-quality habitat during the season that produces the carry-over effect. We apply this model to a threatened warbler population and show the optimal strategy is to purchase more breeding than wintering habitat despite the fact that breeding habitat is over ten times more expensive. Our model provides a framework for developing year-round conservation strategies for migratory animals and has important implications for long-term planning and management. [source] Moisturizer effect on Irritant Dermatitis: an overviewCONTACT DERMATITIS, Issue 2 2006Miki Yokota Moisturizers are empirically used as prevention and treatment of surfactant and irritant dermatitis. Some products state they not only improve barrier function by providing moisturization but also create an environment optimal for healing. Yet, moisturizer clinical efficacy remains a topic of controversy. We reviewed publication from 1992 to 2006 that quantitatively examines moisturizer effectiveness, as an update of our prior overview, Zhai and Maibach in 1998 (2). We intuitively (in a testimonial sense) believe that moisturizers are sometimes effective for preventing and treating irritant dermatitis. However, moisturizer may not be broadly effective (8, 12) and may be relatively specific against certain acids, bases, hydrophilics, and lipophilics. We need to develop principles of what is formulated in moisturizers to improve efficacy; for this purpose, there is a need for experimental moisturizer models for comparative studies. [source] Resource Allocation Effects of Price Reactions to Disclosures,CONTEMPORARY ACCOUNTING RESEARCH, Issue 3 2002Ronald A. Dye Abstract Capital market participants collectively may possess information about the valuation implications of a firm's change in strategy not known by the management of the firm proposing the change. We ask whether a firm's management can exploit the capital market's information in deciding either whether to proceed with a contemplated strategy change or whether to continue with a previously initiated strategy change. In the case of a proposed strategy change, we show that managers can extract the capital market's information by announcing a potential new strategy, and then conditioning the decision to implement the new strategy on the size of the market's price reaction to the announcement. Under this arrangement, we show that a necessary condition to implement all and only positive net present value strategy changes is that managers proceed to implement some strategies that garner negative price reactions upon their announcement. In the case of deciding whether to continue with a previously implemented strategy change, we show that it may be optimal for the firm to predicate its abandonment/continuation decision on the magnitude of the costs it has already incurred. Thus, what looks like "sunk-cost" behavior may in fact be optimal. Both demonstrations show that, in addition to performing their usual role of anticipating future cash flows generated by a manager's actions, capital market prices can also be used to direct a manager's actions. It follows that, in contrast to the usual depiction of the information flows between capital markets and firms as being one way , from firms to the capital markets , information also flows from capital markets to firms. [source] Accounting Recognition, Moral Hazard, and Communication,CONTEMPORARY ACCOUNTING RESEARCH, Issue 3 2000PIERRE JINGHONG LIANG Abstract Two complementary sources of information are studied in a multiperiod agency model. One is an accounting source that partially but credibly conveys the agent's private information through accounting recognition. The other is an unverified communication by the agent (i.e., a self-report). In a simple setting with no communication, alternative labor market frictions lead to alternative optimal recognition policies. When the agent is allowed to communicate his or her private information, accounting signals serve as a veracity check on the agent's self-report. Finally, such communication sometimes makes delaying the recognition optimal. We see contracting and confirmatory roles of accounting as its comparative advantage. As a source of information, accounting is valuable because accounting reports are credible, comprehensive, and subject to careful and professional judgement. While other information sources may be more timely in providing valuation information about an entity, audited accounting information, when used in explicit or implicit contracts, ensures the accuracy of the reports from nonaccounting sources. [source] Agency Relations within the Family Business System: an exploratory approachCORPORATE GOVERNANCE, Issue 3 2003L.A.A. Van den Berghe Researchers use various definitions to describe the family firm. The characteristics of family firms that are stressed in each of these definitions are somehow related to family control. All characteristics together reflect a spectrum of family firm types along one core dimension: family involvement in the firm. However, it is more helpful to distinguish among family firms by using their precise type. Each particular family firm type is characterised by a set of agency relations within and between the family system, ownership system and the business system. This paper is a first attempt to apply the insights from agency theory on a highly simplified (reference) family firm situation where the father is full owner and the daughter manager of the family firm. Agency theory establishes the foundation for the optimal contract conditions between father and daughter. While real life is often characterised by bounded rationality and incomplete information, future research should help identify the "optimal contract" be-tween the family/shareholders and management in various family firm types under these circumstances. [source] A theory for elastic properties of single crystals with microstructure and its application to diffusion induced segregationCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2008T. Blesgen Abstract In this article a general theory for elastically stressed single crystals in the presence of microstructure is presented and an explicit formula for the resulting non-linear stored mechanical energy is obtained. The optimal microstructure under applied stress is characterised and the optimal laminates are identified in 2D. The analysis is based on a sharp lower estimate of the energy that relies on relaxation. The new theory is then used to extend existing models for diffusion induced segregation (DIS) in the case of (Zn,Fe)S single crystals. Numerical simulations based on finite elements are carried out and the results are compared with former computations of the homogeneous case. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Slit-flow ektacytometry: Laser diffraction in a slit rheometerCYTOMETRY, Issue 1 2005Sehyun Shin Abstract Background Deformability of red blood cells (RBCs) is a determinant of blood flow resistance as RBCs pass through small capillaries of the microcirculation. Available techniques for measuring RBC deformability often require a washing process after each measurement, which is not optimal for day-to-day clinical use. Methods A laser diffraction technique has been combined with slit-flow rheometry, which shows significant advances in ektacytometric design, operation, and data analysis. The essential features of this design are its simplicity (ease of operation and no moving parts) and a disposable element that is in contact with the blood sample. Results With slit ektacytometry, the deformation of RBCs subjected to continuously decreasing shear stress in a slit flow can be quickly measured with extremely small quantities of blood. The measurements with the slit ektacytometer were compared with those of LORCA and a strong correlation was apparent. The deformability of the hardened RBCs was markedly lower than that of the normal RBCs. In addition, the young cells showed higher values of the elongation index than did the old cells. Conclusions The newly developed slit ektacytometer can measure RBC deformability with ease and accuracy. In addition, the slit ektacytometer can be easily used in a clinical setting owing to the incorporation of a disposable element that holds the blood sample. © 2005 Wiley-Liss, Inc. [source] Coordinated Capacitated Lot-Sizing Problem with Dynamic Demand: A Lagrangian HeuristicDECISION SCIENCES, Issue 1 2004E. Powell Robinson Jr. ABSTRACT Coordinated replenishment problems are common in manufacturing and distribution when a family of items shares a common production line, supplier, or a mode of transportation. In these situations the coordination of shared, and often limited, resources across items is economically attractive. This paper describes a mixed-integer programming formulation and Lagrangian relaxation solution procedure for the single-family coordinated capacitated lot-sizing problem with dynamic demand. The problem extends both the multi-item capacitated dynamic demand lot-sizing problem and the uncapacitated coordinated dynamic demand lot-sizing problem. We provide the results of computational experiments investigating the mathematical properties of the formulation and the performance of the Lagrangian procedures. The results indicate the superiority of the dual-based heuristic over linear programming-based approaches to the problem. The quality of the Lagrangian heuristic solution improved in most instances with increases in problem size. Heuristic solutions averaged 2.52% above optimal. The procedures were applied to an industry test problem yielding a 22.5% reduction in total costs. [source] Channel Strategies and Stocking Policies in Uncapacitated and Capacitated Supply Chains,DECISION SCIENCES, Issue 2 2002Jayashree Mahajan ABSTRACT A supply chain consisting of a single supplier distributing two independent products through multiple retailers is analyzed in this paper. The supplier needs to incentivize its retailers to adopt stocking policies that are mutually advantageous and that result in the optimal level of market coverage. The focus is on determining the optimal stocking policies for retailers and the resulting distribution strategy given that the supplier has either unlimited or limited capacity. The results provide insights on the optimal distribution strategy and stocking policies for the supply chain. In general, the paper shows that it is optimal for the supplier to use an intensive distribution strategy (i.e., the products are stocked by all retailers). Selective or exclusive strategies are optimal only when retailers are risk averse, stocking synergies exist, and there are differences in demand or supply uncertainties across products. The analysis also shows that retailers hold larger stocks of a product which generates higher supplier margins but only when the supplier has unlimited capacity. If the supplier has limited capacity, then their margins have no effect on retailers' stocking decisions. Contrary to conventional wisdom, retailers hold larger stocks of a product that has less demand uncertainty as compared to one that has more demand uncertainty. [source] Healing and prognosis of teeth with intra-alveolar fractures involving the cervical part of the rootDENTAL TRAUMATOLOGY, Issue 2 2002Miomir Cvek Abstract Healing and long-term prognosis of 94 cervical root fractures were evaluated. The teeth were divided into two groups according to type of fracture: transverse fractures limited to the cervical third of the root (51 incisors) and oblique fractures involving both the cervical and middle parts of the root (43 incisors). Neither the frequency nor the type of fracture healing differed significantly between the two groups. In the material as a whole, healing of the fracture with hard tissue formation was observed in 17 teeth (18%), and healing with interposition of periodontal ligament (PDL) and, in some cases, hard tissue between the fragments in 62 teeth (66%). Fifteen teeth (16%) showed no healing and a radiolucency adjacent to the fracture. Statistical analyses revealed that incomplete root formation and a positive sensibility test at the time of injury were significantly related to both healing and hard tissue repair. The same applied to concussion or subluxation compared with dislocation of coronal fragment, as well as optimal compared with suboptimal reposition of displaced coronal fragments. The type and duration of splinting (or no splinting) appeared to be of no significance for frequency or type of healing of cervical root fractures. During the observation time (mean = 75 months), 19 (44%) of the teeth with transverse fractures and 3 (8%) of those with oblique fractures were lost after healing. In conclusion, fractures in the cervical part of the root had a healing potential and the predictive parameters identified for fractures in other parts of the root seemed to be valid for the healing of cervical root fractures. Transverse fractures appeared to have a significantly poorer long-term prognosis compared to oblique fractures, apparently due to a marked post-treatment mobility, which often led to new luxation caused by even minor impacts. [source] Psychometric evaluation of the mini-social phobia inventory (Mini-SPIN) in a treatment-seeking sample,DEPRESSION AND ANXIETY, Issue 6 2007Justin W. Weeks M.A. Abstract The Mini-Social Phobia Inventory (Mini-SPIN) is a 3-item, self-rated screening instrument to assess social anxiety disorder, but its psychometric properties have not yet been examined in a sample seeking treatment for psychiatric disorders. We analyzed responses from 291 adults who telephoned the Adult Anxiety Clinic of Temple (AACT) seeking treatment for social anxiety or generalized anxiety and worry. The Mini-SPIN demonstrated strong internal consistency. Support for the convergent validity of the Mini-SPIN was provided by moderate correlations with several self-report measures and a clinician-administered measure of social anxiety completed by the subsample of callers who later came to the AACT for evaluation. Furthermore, the Mini-SPIN correlated significantly with two of three measures of functional disability, but not with a measure of life satisfaction. Correlations with measures of other constructs were nonsignificant, providing support for the discriminant validity of the Mini-SPIN. In addition, a cutoff score of 6 on the Mini-SPIN yielded strong sensitivity and diagnostic efficiency in the subsample of treatment seekers that later completed pretreatment evaluation, although the specificity of this cutoff score was not optimal in this sample. Overall, the Mini-SPIN demonstrated sound psychometric properties in this treatment-seeking sample. Depression and Anxiety 24:382,391, 2007. Published 2006 Wiley-Liss, Inc. [source] Schizophrenia treatment: content versus deliveryACTA PSYCHIATRICA SCANDINAVICA, Issue 2009J. Van Os Objective:, To review the evidence supporting the importance of ensuring that patients with psychiatric disorders receive an optimal and appropriate level of non-pharmacological treatment, and how Assertive Community Treatment (ACT) may be able to contribute to this aim. Method:, Analysis of data from selected individual published studies on ACT, in addition to reviews from the Cochrane Library, and other study groups. Results:, Treatment management using ACT appears to offer benefits in terms of reduction in hospitalisation, although there is some debate as to whether this is the most representative outcome measure. Preliminary indications using remission as an outcome measure have also shown promising results in favour of ACT. Conclusion:, While further investigation and validation are necessary, current data indicate that ACT may be an appropriate strategy to facilitate the delivery of treatment to patients with psychotic disorders. [source] Mechanical computation in neuronsDEVELOPMENTAL NEUROBIOLOGY, Issue 11 2009Jummi Laishram Abstract Growth cones are the main motile structures located at the tip of neurites and are composed of a lamellipodium from which thin filopodia emerge. In this article, we analyzed the kinetics and dynamics of growth cones with the aim to understand two major issues: first, the strategy used by filopodia and lamellipodia during their exploration and navigation; second, what kind of mechanical problems neurons need to solve during their operation. In the developing nervous system and in the adult brain, neurons constantly need to solve mechanical problems. Growth cones must decide how to explore the environment and in which direction to grow; they also need to establish the appropriate contacts, to avoid obstacles and to determine how much force to exert. Here, we show that in sparse cultures, filopodia grow and retract following statistical patterns, nearly optimal for an efficient exploration of the environment. In a dense culture, filopodia exploration is still present although significantly reduced. Analysis on 1271, 6432, and 185 pairs of filopodia of DRG, PC12 and Hippocampal neurons respectively showed that the correlation coefficient |,| of the growth of more than 50% of filopodia pairs was >0.15. From a computational point of view, filopodia and lamellipodia motion can be described by a random process in which errors are corrected by efficient feedback loops. This article argues that neurons not only process sensory signals, but also solve mechanical problems throughout their entire lifespan, from the early stages of embryogenesis to adulthood. © 2009 Wiley Periodicals, Inc. Develop Neurobiol, 2009 [source] | ||||||||||||||||||||||||||||||||||