bluuebunny/crossref_metadata_2025 huggingface dataset:
Tantalum and Tantalum Compounds
Authors: Lambert John B.
Published: January 2011

Tantalum, discovered in 1802, was not produced in significant quantities until the invention of the solid tantalum capacitor. This tough, ductile silvery gray metal is used primarily in electronic capacitors and a variety of chemical manufacturing applications. Only about 50% of processor demand for tantalum is provided by mine production. The other sources, synthetic concentrates, scrap recycle, and inventory movement, constitute the remainder. Corrosion resistance and the ability to support a stable anodic oxide film make tantalum an excellent material for prosthetics and biomedical devices as well as a substrate for capacitor dielectrics. Tantalum is used also for reactor vessel liners, heat exchangers, and heat shields. The corrosion resistance imparted to tantalum by the passivating surface thermal layer makes the metal inert to most hazards associate with metals. Potassium heptafluorotantalate, from which tantalum metal is formed, is the most important tantalum compound. Other compounds are used in cemented carbides for cutting tools, cermets, waveguides, and other optical and electronic devices.
Ant Colony Optimization
Authors: Dorigo Marco , Montes de Oca Marco A. , Oliveira Sabrina , Stützle Thomas
Published: January 2011

Ant colony optimization (ACO) is a class of algorithms for tackling optimization problems that is inspired by the pheromone trail laying and following behavior of some ant species. In ACO, (artificial) ants construct candidate solutions to the problem instance under consideration. Their solution construction is stochastically biased by (artificial) pheromone trails, which are represented in the form of numerical information that is associated with appropriately defined solution components, and possibly by heuristic information based on the input data of the problem instance being solved. A key aspect of ACO algorithms is the use of a positive feedback loop implemented by iterative modifications of the artificial pheromone trails that are a function of the ants' search experience; the goal of this feedback loop is to bias the colony toward the most promising solutions.

The ACO metaheuristic is a high‐level algorithmic framework for applying the above ideas to the approximate solution of discrete optimization problems. In this article, we review the most important developments on the algorithmic side of ACO and give a concise summary of approaches followed for the hybridization of ACO algorithms with other techniques, the main application areas of ACO, and the available theoretical results.
Antithetic Variates
Authors: He Donghai , Chen Chun‐Hung
Published: January 2011

Antithetic variates is a useful and simple technique for variance reduction in Monte Carlo simulation. The basic idea is to induce negative correlation into random samples. This article gives an overview of antithetic variates and discusses their recent development. Numerical results are presented to illustrate their effectiveness.
Assessing Remaining Useful Lifetime of Products
Authors: Kara Sami
Published: January 2011

The requirement for reliable methodologies to assess the remaining useful life of used components has become crucial in order to implement various end‐of‐life strategies. This article presents the latest development in predicting the remaining useful lifetime of used components. It takes the physical and the technological life aspects into account for an integrated assessment. There are three main parts of this article. First, the remaining physical life of used components is derived based on the failure rate data and the statistical analysis of usage life. Secondly, the use of technology forecasting technique to predict the remaining technological life. Finally, the resulting estimations from the two aspects are combined to obtain an integrated assessment for estimating the remaining useful life of components.
Axiomatic Models of Perceived Risk
Authors: Jia Jianmin , Dyer James S. , Butler John C.
Published: January 2011

This article presents two classes of measures for perceived risk based on decomposing a lottery into its mean and its dispersion about the mean, or standard risk. One of the classes of risk measures presumes that there is no risk when there is no uncertainty involved, and the other allows different degenerate lotteries to be evaluated with different values of “risk.” The former has more prescriptive appeal in risky decision making, but the latter may have more descriptive power for subjective risk judgments. These risk measures can also incorporate the asymmetric effects of losses and gains on perceived risk when an appropriate form of the standard measure of risk is applied. These perceived risk models unify a large body of empirical evidence regarding risk judgments, and provide sufficient flexibility to capture better perceptions of risk than previously developed risk models. Further, they provide clear ways to accommodate financial measures of risk and psychological measures of risk, and they can be incorporated into preference models based on mean‐risk trade‐offs.
Bayesian Aggregation of Experts' Forecasts
Authors: Lichtendahl Kenneth C.
Published: January 2011

Decision makers often consult multiple experts when trying to forecast a future event or quantity. Once the experts' forecasts are obtained, aggregating them into a single forecast can present a significant challenge. The simplest way to aggregate the experts' forecasts is to average them. The Bayesian decision maker, instead, uses the experts' forecasts as data to update prior beliefs about the event or quantity of interest. We examine several prototypical Bayesian aggregation models. We highlight the two main assessment challenges a decision maker faces in constructing such models: (i) judging each expert's discrimination or dependency between the event of interest and the expert's forecast and (ii) judging the dependency between the experts' forecasts, or overlap in their information sources.
Birth‐and‐Death Processes
Authors: Degirmenci Guvenc
Published: January 2011

A birth‐and‐death (BD) process is a continuous‐time Markov chain on the nonnegative integers whose transitions are restricted to its nearest neighbors. These processes have enjoyed wide popularity in a diverse set of fields. This article formally defines the BD process, reviews basic results for its transient and asymptotic analysis, discusses some special cases, and describes two applications in queueing theory.
Competing Risks and Limited Failure
Authors: Basu Sanjib
Published: January 2011

In engineering, biomedical, or other studies involving time‐to‐event outcomes, a fraction of the units or subjects in a limited failure population may continue to survive a risk. This may happen, for example, if a subject is cured of cancer or if a unit is immune from the risk of infant mortality. Another common occurrence is the setting of competing risks where subjects or units are exposed to multiple risks one of which may eventually cause the occurrence of the event, such as failure or recurrence or death. This article considers and reviews the limited failure competing risks model where a fraction of the units or subjects can be failure‐free from only one of the competing risks but not from the others. The case of masking, when the causes of events for some of the items are not exactly identified or recorded, is also considered.
Clustering
Authors: Iyigun Cem
Published: January 2011

Clustering is a process of partitioning (classification) of data points (observations, patterns) into disjoint groups (clusters) of similar objects. The search for clusters is a method ofunsupervisedlearning, used in many areas, including statistics, machine learning, data mining, operations research, bioinformatics, facility location, and across multiple application areas including genetics, taxonomy, medicine, marketing, finance, and e‐commerce. This article presents an overview of clustering methods and reviews the literature related to different clustering algorithms and methods.
Column Generation
Authors: Lübbecke Marco E.
Published: January 2011

Column generation is an indispensable tool in computational optimization to solve a mathematical program by iteratively adding the variables of the model. Even though the method is simple in theory, there are many algorithmic choices and we discuss the most common ones. Particular emphasis is placed on the dual interpretation, relating column generation to Langrangian relaxation and cutting plane algorithms, which revealed several critical issues like the need for dual variable stabilization techniques. We conclude with some advice for computer implementations.
Conic Optimization Software
Authors: Imre Pólik
Published: January 2011

We give an overview of cone optimization software, with special attention to the differences between the existing packages. We assume that the reader is familiar with the theory and algorithms of cone optimization, thus technical details are kept at a minimum. We also outline current research trends and area of potential improvement.
Scheduling Seaside Resources at Container Ports
Authors: Meisel Frank
Published: January 2011

This article provides an overview of operational planning and scheduling problems at seaport container terminals. It considers problems that deal with the seaside resources of a terminal, namely the berth space and the quay cranes, in detail. The corresponding problems of berth allocation, crane assignment, and crane scheduling are investigated in detail by providing comprehensive literature surveys and examples of mathematical models that are found in the recent literature. Finally, issues of further research are outlined.
Damage, Stress, Degradation, Shock
Authors: Kahle Waltraud
Published: January 2011

First, we give an overview of the most common degradation models. We describe in more detail two degradation models where the first one is based on a Wiener process and the second one is assumed to be generated by a position‐dependent marking of a doubly stochastic Poisson process. A failure occurs when the degradation reaches a given level first time. Some characteristics of these processes are described.
Inventory Record Inaccuracy in Retail Supply Chains
Authors: DeHoratius Nicole
Published: January 2011

Inventory record inaccuracy (IRI), defined as the discrepancy between the recorded inventory quantity and the actual inventory quantity physically available on the shelf, is a substantial problem in retailing. This article summarizes the research documenting the problem of IRI within retail supply chains and reviews several potential solutions to IRI offered by operations management researchers. In addition, this article explores how execution problems within retail distribution centers (DCs) contribute to store‐level IRI. Through direct observations and interviews with retail employees, we identify numerous errors that occur within the retail DC and how such errors create a mismatch between actual and recorded store inventory. We argue that it is critical to detect, determine the root cause of, and correct such errors in an effort to prevent them from cascading from one stage of the distribution process to the next. We claim error prevention in distribution, similar to quality improvement in manufacturing, requires improving workforce practices, fool‐proofing operational processes, and appropriate incentive design. We conclude with our recommendations for further study on this topic.
Memetic Algorithms
Authors: Moscato Pablo , Berretta Regina , Cotta Carlos
Published: January 2011

Memetic algorithms (MAs) are population‐based search strategies that have been extensively used as metaheuristics for optimization problems in a large number of domains. They are based on the synergistic combination of different algorithmic solvers, with an emphasis on hybridizations with advanced mathematical programming techniques. The synergies are obtained by balancing competitive and cooperative interactions among software agents, which are allowed to have different search strategies and sporadically interact. The paradigm was specially designed for heterogeneous distributed systems and parallel computers 20 years ago. We present a brief historical perspective on MAs, an outline of their algorithmic structural template, and some relevant design aspects of these techniques. The strong momentum of the field is further illustrated by an overview of up‐to‐date algorithmic developments of the paradigm and by highlighting some of the most recent applications published in the literature.
Optimal Reliability Allocation
Authors: Malaiya Yashwant K.
Published: January 2011

The overall reliability of a complex system, designed as an assembly of subsystems, depends on the subsystem reliability metrics. The cost of each subsystem is a function of its reliability. This article considers the problem of allocating the reliability values to minimize the total cost while achieving the reliability target. The reliability allocation problem is applicable to mechanical and electrical systems as well as computer hardware and software. The approach involves expressing the system reliability in terms of the subsystem reliability values and specifying the cost function for each subsystem, which allows setting up an optimization problem. Software reliability allocation is examined as a detailed example and some preliminary apportionment approaches are presented. While in many cases, it is possible to use exact optimization methods, a complex case may require use of iterative approaches.
Array‐based MLPA to detect recurrent copy number variations in patients with idiopathic mental retardation
Authors: Rooms Liesbeth , Vandeweyer Geert , Reyniers Edwin , van Mol Kurt , de Canck Ilse , Van der Aa Nathalie , Rossau Rudi , Kooy R. Frank
Published: January 2011

Microdeletions, either subtelomeric or interstitial, are responsible for the mental handicap in approximately 10–20% of all patients. Currently, Multiplex Ligation‐dependent Probe Amplification (MLPA) is widely used to detect these small aberrations in a routine fashion. Although cost‐effective, the throughput is low and the degree of multiplexing is limited to maximally 40–50 probes. Therefore, we developed an array‐based MLPA method, with probes identified by unique tag sequences, allowing the simultaneous analysis of 180 probes in a single experiment thereby covering all known mental retardation loci with at least two probes. We screened 120 patients with idiopathic mental retardation. In this group we detected 6 aberrations giving a detection rate of 5%, consistent with similar studies. In addition we tested 293 patients with mental retardation who were negative for fragile X syndrome and commercially available subtelomeric MLPA. We found seven causative rearrangements in this group (detection rate of 2.4%) thereby illustrating the value of including probes for interstitial microdeletion syndromes and additional probes in the telomeric regions in targeted screening sets for mental retardation. Array‐based MLPA may thus be a good candidate to develop probe sets that rapidly detect copy number changes of disease associated loci in the human genome. This method may become a valuable tool in a routine diagnostic setting as it is a fast, user‐friendly and relatively low‐cost technique providing straightforward results requiring only 125 ng of genomic DNA. © 2011 Wiley‐Liss, Inc.
Cerium‐catalyzed tandem synthesis of 2‐substituted benzothiazoles in PEG
Authors: Jin Hui‐Le , Cheng Tian‐Xing , Chen Jiu‐Xi
Published: January 2011

An efficient and convenient condensation reaction of 2‐aminothiophenol with aldehydes catalyzed by a catalytic amount of ceric ammonium nitrate in polyethylene glycol was investigated. As a result, a set of diverse 2‐substituted benzothiazoles such as 2‐phenylbenzothiazole as well as its p‐Me, p‐NO2, p‐F, p‐Cl, p‐Br, o‐OMe, p‐OMe and 2‐furyl, 2‐pyridyl and styryl derivatives were obtained in good to excellent yields for 5 h at room temperature. Additionally, the catalyst system was recovered and reused several times without evident loss in activity. Copyright © 2011 John Wiley & Sons, Ltd.
Synthesis and Anticancer Activity of New 2‐Aryl‐4H‐3,1‐benzothiazines
Authors: Niewiadomy Andrzej , Matysiak Joanna , Karpińska Monika M.
Published: January 2011

New compounds of 2‐aryl‐4H‐3,1‐benzothiazine set were synthesized and tested for their antiproliferative activity as part of our research in the antitumor field. The title compounds were obtained by the reaction of aryl‐modified sulfinylbis((2,4‐dihydroxyphenyl)methanethione) with 2‐aminobenzyl alcohols. The reaction proceeded through thiobenzanilide intermediates, which were converted to the 4H‐3,1‐benzothiazine fused ring by an endocyclization process. The structures of compounds were identified from elemental, IR, 1H‐NMR, 13C‐NMR, and MS spectra analyses. The cytotoxicity in vitro against four human cancer cell lines was determined. The antiproliferative properties of some compounds were more beneficial than cisplatin studied comparatively.
Effects of Metal Salophene and Saldach Complexes on Lymphoma and Leukemia Cells
Authors: Hille Annegret , Wolf Tanja , Schumacher Petra , Ott Ingo , Gust Ronald , Kircher Brigitte
Published: January 2011

Schiff base transition metal complexes are an important class of compounds with great potential for therapeutic interventions. However, data on antileukemic and antilymphoma effects of these complexes are limited. The activity of N,N′‐bis(salicylidene)‐1,2‐phenylenediamine (salophene, 1), its iron(II/III) and manganese(II/III) complexes as well as rac‐trans‐N,N′‐bis(salicylidene)‐1,2‐cyclohexanediamine (saldach, 2) and its respective iron(II/III) complexes was evaluated against U‐937 non‐Hodgkin's lymphoma and the HL‐60, SUP‐B15, and K‐562 leukemia cell lines. The free ligands induced in all cell lines, if at all, only marginal, concentration‐dependent growth inhibitory effects, and did not trigger Cu/Zn superoxide dismutase (Cu/Zn SOD) release or induce apoptosis. [FeII(salophene)] (3) and [FeIII(salophene)Cl] (4) blocked cellular growth, caused a strong release of Cu/Zn SOD and induced apoptosis. In contrast, the manganese analogs [MnII(salophene)] (5) and [MnIII(salophene)OAc] (6) inhibited cell growth, caused the programmed cell death only at higher concentrations and did not provoke release of Cu/Zn SOD in any of the four cell lines. Weaker cell death‐promoting effects were observed when the salophene moiety of 3 and 4 was replaced with saldach (complexes 7 and 8), indicating the influence exerted by the ligand structure. In conclusion, Schiff base transition metal complexes induce strong inhibitory effects on human lymphoma and leukemia cells.
An assessment of models to estimate pedestrian demand based on the level of activity
Authors: Pulugurtha Srinivas S. , Repaka Sudha R.
Published: January 2011

This paper presents the development and assessment of models to estimate pedestrian demand based on the level of pedestrian activity (high and low). As activity varies by the time of the day, temporal variations were evaluated by considering different time periods. Data collected at 128 low and 48 high pedestrian activity signalized intersections (a total of 176 signalized intersections) in the City of Charlotte, North Carolina were used to develop and assess the models using stepwise regression analysis through backward elimination of independent variables (includes demographic, land use, and network characteristics). The use of different buffer widths (proximal area) to extract these characteristics was also evaluated. Results, in general, show that pedestrian demand varied by the level of activity, explanatory variables extracted by buffer width, and time of the day. The estimates from the models could be used in transportation planning (identify required pedestrian facilities, resource allocation), safety, and operational analyses. Copyright © 2010 John Wiley & Sons, Ltd.
Effects of formulation and route of administration on the systemic availability of Ex‐RAD®, a new radioprotectant, in preclinical species
Authors: Chun Amy W. , Freshwater Robert E. , Taft David R. , Gillum Amanda M. , Maniar Manoj
Published: January 2011

ON 01210.Na (Ex‐RAD®) is a novel small molecule under development by Onconova Therapeutics, Inc. as a radiation protection agent. The purpose of this investigation was to evaluate the effect of various formulation approaches on the systemic exposure of ON 01210.Na.In vitroexperiments were used to characterize the plasma binding and metabolic stability of ON 01210.Na using hepatocytes from several animal species (mouse, rat, rabbit, dog, monkey and human).In vivostudies were performed in rats, rabbits, dogs and monkeys, and involved several routes of administration (intravenous, subcutaneous, oral). Plasma protein binding was high across species (>83%), and the rate of ON 01210.Na metabolism was highest in rat and mouse hepatocytes. After intravenous administration, ON 01210.Na demonstrated biphasic elimination from the plasma. Systemic exposure parameters (Cmax,AUC) were dose‐proportional up to 100 mg/kg. Following subcutaneous dosing, ON 01210.Na showed relatively low bioavailability upon administration of the suspension formulation. Developing a solution formulation significantly increased the bioavailability of the drug. This solution formulation demonstrated significant oral bioavailability in rabbit (70%) and monkey (30%). The findings from these preclinical studies provide an overview of the systemic disposition of ON 01210.Na, aiding in the development of optimal formulations and routes of administration for pivotal animal efficacy and clinical safety studies. A solution formulation of ON 01210.Na for s.c. administration is being developed, in addition to an oral dosage form for potential use of the compound as a radioprotectant and a radiation‐mitigating agent in wider military and civilian populations. Copyright © 2011 John Wiley & Sons, Ltd.
Detecting and adjusting for small‐study effects in meta‐analysis
Authors: Rücker Gerta , Carpenter James R. , Schwarzer Guido
Published: January 2011

Publication bias and related types of small‐study effects threaten the validity of systematic reviews. The existence of small‐study effects has been demonstrated in empirical studies. Small‐study effects are graphically diagnosed by inspection of the funnel plot. Though observed funnel plot asymmetry cannot be easily linked to a specific reason, tests based on funnel plot asymmetry have been proposed. Beyond a vast range of funnel plot tests, there exist several methods for adjusting treatment effect estimates for these biases. In this article, we consider the trim‐and‐fill method, the Copas selection model, and more recent regression‐based approaches. The methods are exemplified using a meta‐analysis from the literature and compared in a simulation study, based on binary response data. They are also applied to a large set of meta‐analyses. Some fundamental differences between the approaches are discussed. An assumption common to the trim‐and‐fill method and the Copas selection model is that the small‐study effect is caused by selection. The trim‐and‐fill method corresponds to an unknown implicit model generated by the symmetry assumption, whereas the Copas selection model is a parametric statistical model. However, it requires a sensitivity analysis. Regression‐based approaches are easier to implement and not based on a specific selection model. Both simulations and applications suggest that in the presence of strong selection both the trim‐and‐fill method and the Copas selection model may not fully eliminate bias, while regression‐based approaches seem to be a promising alternative.
How to quantify protein diffusion in the bacterial membrane
Authors: van den Wildenberg Siet M. J. L. , Bollen Yves J. M. , Peterman Erwin J. G.
Published: January 2011

Lateral diffusion of proteins in the plane of a biological membrane is important for many vital processes, including energy conversion, signaling, chemotaxis, cell division, protein insertion, and secretion. In bacteria, all these functions are located in a single membrane. Therefore, quantitative measurements of protein diffusion in bacterial membranes can provide insight into many important processes. Diffusion of membrane proteins in eukaryotes has been studied in detail using various experimental techniques, including fluorescence correlation spectroscopy (FCS), fluorescence recovery after photobleaching (FRAP), and particle tracking using single‐molecule fluorescence (SMF) microscopy. In case of bacteria, such experiments are intrinsically difficult due to the small size of the cells. Here, we review these experimental approaches to quantify diffusion in general and their strengths and weaknesses when applied to bacteria. In addition, we propose a method to extract multiple diffusion coefficients from trajectories obtained from SMF data, using cumulative probability distributions (CPDs). We demonstrate the power of this approach by quantifying the heterogeneous diffusion of the bacterial membrane protein TatA, which forms a pore for the translocation of folded proteins. Using computer simulations, we study the effect of cell dimensions and membrane curvature on measured CPDs. We find that at least two mobile populations with distinct diffusion coefficients (of 7 and 169 nm2 ms−1, respectively) are necessary to explain the experimental data. The approach described here should be widely applicable for the quantification of membrane‐protein diffusion in living bacteria. © 2011 Wiley Periodicals, Inc. Biopolymers 95: 312–321, 2011.
Chain‐to‐chain inventory transshipment model and robust switch control in CSC networks
Authors: Li Jizi , Xiong Naixue , Park Jong Hyuk , Liu Chunling , Ma Shihua , Sun Linfu
Published: January 2011

On the basis of CSC (Cluster Supply Chain) networks with two four‐echelon single supply chains, chain‐to‐chain inventory transshipment between two retailers is taken into account in the context of the two single chains cooperation. The uncertain robust switched control system model is built. Meanwhile, the methodology of robust optimization is introduced to minimize the bullwhip effect, and the solution of optimal decision serials is explored utilizing H‐infinity switched control algorithm. The online decision‐making simulation framework structure is developed to demonstrate the switching procedure. The simulation example proves that chain‐to‐chain inventory transshipment in CSC networks and robust switch control method can effectively weaken the bullwhip effect, reduce stock, dwindle fluctuation of order, and improve response to cluster market. Copyright © 2011 John Wiley & Sons, Ltd.
Nitric Oxide Transport in Blood: A Third Gas in the Respiratory Cycle
Authors: Doctor Allan , Stamler Jonathan S.
Published: January 2011

The trapping, processing, and delivery of nitric oxide (NO) bioactivity by red blood cells (RBCs) have emerged as a conserved mechanism through which regional blood flow is linked to biochemical cues of perfusion sufficiency. We present here an expanded paradigm for the human respiratory cycle based on the coordinated transport of three gases: NO, O2, and CO2. By linking O2and NO flux, RBCs couple vessel caliber (and thus blood flow) to O2availability in the lung and to O2need in the periphery. The elements required for regulated O2‐based signal transduction via controlled NO processing within RBCs are presented herein, includingS‐nitrosothiol (SNO) synthesis by hemoglobin and O2‐regulated delivery of NO bioactivity (capture, activation, and delivery of NO groups at sites remote from NO synthesis by NO synthase). The role of NO transport in the respiratory cycle at molecular, microcirculatory, and system levels is reviewed. We elucidate the mechanism through which regulated NO transport in blood supports O2homeostasis, not only through adaptive regulation of regional systemic blood flow but also by optimizing ventilation‐perfusion matching in the lung. Furthermore, we discuss the role of NO transport in the central control of breathing and in baroreceptor control of blood pressure, which subserve O2supply to tissue. Additionally, malfunctions of this transport and signaling system that are implicated in a wide array of human pathophysiologies are described. Understanding the (dys)function of NO processing in blood is a prerequisite for the development of novel therapies that target the vasoactive capacities of RBCs. © 2011 American Physiological Society.Compr Physiol1:541‐568, 2011.
Carbon Monoxide Transport and Actions in Blood and Tissues
Authors: Thom Stephen R.
Published: January 2011

This chapter will discuss the transport of carbon monoxide (CO) from the environment to the tissues of the body and physiological effects on blood‐borne cells and perivascular tissues. It will review the physiology of CO exchange between alveolar gas and pulmonary capillary blood, dynamics of hemoglobin transport, the effects of CO on blood elements, and the effects of CO on extravascular tissues at the capillary bed. Effects of CO from exogenous and endogenous sources on the activities of different proteins will be reviewed. Because CO binds competitively to heme‐containing proteins its effects depend on CO concentration relative to alternative ligands. Therefore, some discussion is devoted to how nitric oxide and hydrogen sulfide influence CO effects. © 2011 American Physiological Society.Compr Physiol1:421‐446, 2011.
A novel theory on parallel repeater‐insertion methodologies for long on‐chip interconnects
Authors: Awwad Falah R. , Nekili Mohamed , Sawan Mohamad
Published: January 2011

Repeaters are now widely used to enhance the performance of long on‐chip interconnects in CMOS devices. For RC‐as well as RLC‐modeled interconnects, parallel repeaters (PRs) have proved to be superior to serial ones. In a previous work, a new regeneration technique, named variable‐segment, was proven to outperform other existing regeneration techniques including variable‐repeater techniques. In this paper, an approximate analytical delay model is presented for both the variable‐repeater and variable‐segment parallel regeneration techniques. This model is used to confirm the optimality of our design and is built based on first and second‐moment transfer functions, which take into account the inductive effects of interconnects. HSpice electrical and C + +/MATLAB simulations are conducted to assess the performance of the proposed optimization methodology using 0.25‐µm CMOS technology. The mathematical simulation results are remarkably in agreement with those obtained from electrically simulated variable‐repeater and variable‐segment structures which are used in this work to regenerate interconnect lengths ranging from 0.1 to 10 cm. This work is part of a first‐of‐its‐kind global theory on PRs in repeater‐insertion methodologies for long on‐chip interconnects. This theory aims at exploring the different degrees of freedom in interconnect modeling as well as repeater type and design parameters. Copyright © 2011 John Wiley & Sons, Ltd.
Current‐fed isolated PFC pre‐regulator for multiple LED lamps with extended lifetime
Authors: Qu Xiaohui , Wong Siu‐Chung , Tse Chi K.
Published: January 2011

To emit high‐quality LED light, one or a bin of LED lamp(s) is normally driven by a PWM‐controlled constant current source to minimize device variation and achieve accurate brightness control. Powered from offline AC mains, the front‐end power converters should provide a relatively low DC voltage bus for the inputs of post‐end LED current regulators. To match the long lifetime of LEDs, the whole LED driver (ballast) should work as durably as the LEDs. However, the lifetime of the driver is usually limited by the high‐voltage electrolytic charge storage capacitors used in conventional PFC pre‐regulators. In this paper, our previously proposed resonant current‐fed isolated PFC pre‐regulator is extended to operate in discontinuous conduction mode (DCM). It allows the use of the low‐voltage storage capacitors on the transformer secondary, and therefore extends the overall lifetime of the LED lighting system. A detailed procedure for finding the expected lifetime of the low‐voltage electrolytic capacitor is given. As before, the high‐voltage stress on the main switches, which is typical in current‐fed isolated converters, is reduced substantially by taking advantage of the transformer leakage inductance necessary for resonance. Additionally, high efficiency is ensured by the use of dual non‐cascading structures. Steady‐state state‐space averaging analysis is performed for designing the converter in DCM operation. A prototype converter is built to verify performance of the proposed PFC LED pre‐regulator. Copyright © 2011 John Wiley & Sons, Ltd.
Critical factors of indirect determination of 3‐chloropropane‐1,2‐diol esters
Authors: Hrncirik Karel , Zelinkova Zuzana , Ermacora Alessia
Published: January 2011

Several indirect methods have been developed for the determination of 3‐chloropropane‐1,2‐diol (3‐MCPD) esters in fat matrices, but the variation between these methods leads to an uncertainty about the comparison of the results. All the indirect methods are based on the conversion of 3‐MCPD esters into free 3‐MCPD upon transesterification (either in acid or alkaline solution), its purification, derivatisation and instrumental analysis. In this study, major critical factors of the methodology, particularly transesterification, salting out and the choice of internal standard, were evaluated. 3‐MCPD showed low stability under the conditions of alkaline transesterification (only around 40% recovery) affecting the sensitivity of the method. Furthermore, the results obtained within the first 1–2 min were 10–20% higher than those obtained at longer (5–10 min) transesterification time. A comparison of results obtained by using two different internal standards (free or esterified form of deuterated 3‐MCPD) revealed a slight overestimation (7–15%) when free deuterated 3‐MCPD was used, which may be possibly explained by the different behaviour of the both forms during alkaline transesterification. The use of different salts and pH values of the reaction medium during salting out step had a major impact on the results due to the formation of additional 3‐MCPD. Other compounds, like glycidyl esters, present in oil samples may be converted to 3‐MCPD during this step, however, the conversion was not complete and varied substantially (12–93%) in dependence on the pH value of the medium. The method based on acid transesterification showed better selectivity and robustness.
Survey of US academic hospitalist leaders about mentorship and academic activities in hospitalist groups
Authors: Harrison Rebecca , Hunter Alan J. , Sharpe Bradley , Auerbach Andrew D.
Published: January 2011

BACKGROUND:

Few data describe the structure, activities, and goals of academic hospital medicine groups.

METHODS:

We carried out a cross sectional email survey of academic hospitalist leaders. Our survey asked about group resources, services, recruitment and growth, as well as mentoring of faculty, future priorities, and general impressions of group stability.

RESULTS:

A total of 57 of 142 (40%) potential hospitalist leaders responded to our email survey. Hospitalist groups were generally young (<5 years old). Hospitalist group leaders worried about adequate mentorship and burnout while placing a high priority on avoiding physician turnover. However, most groups also placed a high priority on expanding nonclinical activities (teaching, research, etc.). Leaders felt financially and philosophically unsupported, a sentiment which seemed to stem from being viewed primarily as a clinical rather than an academic service.

CONCLUSION:

Academic hospital medicine groups have an acute need for mentoring and career development programs. These programs should target both individual hospitalists and their leaders while also helping to enhance scholarly work. Journal of Hospital Medicine 2011;6:5–9. © 2011 Society of Hospital Medicine.
Production of biodiesel with glycerol carbonate by non‐catalytic supercritical dimethyl carbonate
Authors: Ilham Zul , Saka Shiro
Published: January 2011

New biodiesel production processes comprising one‐step and two‐step supercritical dimethyl carbonate methods have been pioneered. The use of dimethyl carbonate allows the reaction conditions to be mild and thus avoid unwanted deterioration of substrates during reaction. In this process, without any catalyst applied, supercritical dimethyl carbonate converts triglycerides (rapeseed oil) into fatty acid methyl esters (FAME) along with glycerol carbonate as a value‐added by‐product, instead of glycerol. Free fatty acids could be also converted into FAME so that the total yield of biodiesel for both methods resulted in over 96 wt%. In addition, the produced FAME satisfy the fuel requirements for the international standards of biodiesel specification.
Reversed‐phase analysis of triacylglycerols by ultra performance liquid chromatography‐evaporative light scattering detection (UPLC‐ELSD)
Authors: Ross Keri L. , Hansen Steven L. , Tu Travis
Published: January 2011

An improved reversed‐phase (RP) method has been developed for the analysis of triacylglycerols (TAG) in fats and oils. This method has shown superior performance over traditional reversed‐phase liquid chromatographic (LC) methods in speed and resolution, and equivalent to superior performance in quantitation accuracy (101%–109%) and reproducibility (1.3%–5.8% RSD). The method can easily be adjusted for use with different oils by simple modification of the gradient and run time. Additionally, a mobile phase is used that is compatible with liquid chromatography/mass spectrometry (LC/MS) that when required, can aid in identification of TAG, for which many standards do not exist. This method is suited to a broad number of applications including (but not limited to) research and development of new oils, quality control, production of industrial or edible oils, and seed strain selection.
Pharmacological postconditioning protects against hepatic ischemia/reperfusion injury a
Authors: Dal Ponte Caterina , Alchera Elisa , Follenzi Antonia , Imarisio Chiara , Prat Maria , Albano Emanuele , Carini Rita
Published: January 2011

Postconditioning is a procedure based on the induction of intracellular protective reactions immediately after the onset of reperfusion. Because of the growing need to prevent ischemia/reperfusion (I/R) injury during liver surgery and transplantation, we investigated the possibility of pharmacologically inducing hepatic postconditioning. The effects of the adenosine A2A receptor agonist 2p-(2-carboxyethyl)-phenyl-amino-5′-N-ethylcarboxyamido-adenosine (CGS21680; 5 μmol/L) and the phosphatase and tensin homologue deleted from chromosome 10 (PTEN) inhibitor dipotassium bisperoxo-(5-hydroxypyridine-2-carboxyl)-oxovanadate [bpV(HOpic); 250 nmol/L] were investigated in primary rat hepatocytes during reoxygenation after 24 hours of cold storage and in an in vivo model of rat liver warm I/R. The addition of CGS21680 at reoxygenation significantly reduced hepatocyte death through the activation of the phosphoinositide 3-kinase (PI3K)-protein kinase B (PKB)/Akt signal pathway and through the reduction of the intracellular level of PTEN. PTEN lowering was associated with the increased generation of reactive oxygen species after A2A receptor-mediated stimulation of β-nicotinamide adenine dinucleotide phosphate oxidase (NOX). The inhibition of PI3K or NOX with wortmannin or diphenyleneiodonium chloride, respectively, and the addition of the antioxidant N,N′-diphenyl-p-phenylenediamine reversed the effects of CGS21680. The PTEN inhibitor bpV(HOpic) mimicked the protection provided by CGS21680 against reoxygenation damage. An in vivo rat treatment with CGS21680 or bpV(HOpic) during reperfusion after 1 hour of partial hepatic ischemia also promoted PKB/Akt activation and ameliorated alanine aminotransferase release and histological lesions induced by 2 hours of reperfusion. We conclude that adenosine A2A receptor agonists and PTEN inhibitors are possibly useful agents for the pharmacological induction of postconditioning in the liver.
Liver Transpl, 2011. © 2011 AASLD.
Transplantation for liver failure in patients with sickle cell disease
Authors: Hurtova Monika , Bachir Dora , Lee Ketty , Calderaro Julien , Decaens Thomas , Kluger Michael D. , Zafrani Elie Serge , Cherqui Daniel , Mallat Ariane , Galactéros Frédéric , Duvoux Christophe
Published: January 2011

Sickle cell disease (SCD) frequently affects the liver; if acute liver failure (ALF) develops, the only potentially effective therapeutic option is liver transplantation (LT). Only 12 patients for whom LT was performed for SCD-related ALF have been described so far. We report a retrospective series of 6 adult patients with SCD (3 men and 3 women, median age = 40.1 years) who underwent emergency LT. The indication for LT was ALF complicating cirrhosis in 5 patients (hepatitis C/iron overload-induced cirrhosis in 3 and iron overload-induced cirrhosis in 2); one patient had autoimmune hepatitis. The median follow-up was 52.7 months (0.5-123 months). The 1-, 3-, 5-, and 10-year survival rates were 83.3%, 66.7%, 44.4%, and 44.4%, respectively. One patient died of hepatocellular failure precipitated by hyperacute allograft rejection on post-LT day 10. Soon after LT, 2 patients developed seizures; in 1 case, the seizures were a complication of early calcineurin inhibitor-induced leukoencephalopathy. Four long-term survivors benefited from specific management of SCD; specifically, the hemoglobin S fraction was maintained below 30% and the total hemoglobin level was maintained between 8 and 10 g/dL. Two patients had mild vaso-occlusive crises. Three patients experienced a recurrence of hepatitis C virus (HCV) infection; 2 of these patients experienced reversible neurological complications while they were receiving antiviral treatment. Carefully selected patients with SCD may benefit from emergency LT. However, such patients seem to be particularly susceptible to neurological complications after LT. In contrast, severe SCD-related crises do not seem to recur if specific management is provided. Outcomes may be improved if the neurological complications can be minimized; for example, the administration of a calcineurin inhibitor can be delayed, and the management of HCV infection recurrence can be improved.
Liver Transpl, 2011. © 2011 AASLD.
Simultaneous liver and kidney transplantation using donation after cardiac death donors
Authors: LaMattina John C. , Mezrich Joshua D. , Fernandez Luis A. , D'Alessandro Anthony M. , Bellingham Janet M. , Musat Alexandru I. , Foley David P.
Published: January 2011

Although the use of donation after cardiac death (DCD) donor organs has been shown to be a viable option for liver and kidney transplant recipients, outcomes after simultaneous liver and kidney (SLK) transplantation using DCD donors are less clear. We performed a retrospective analysis of 37 adult, primary SLK transplants performed at our center between January 1, 1998 and December 31, 2008. Thirty-two patients received donation after brain death (DBD) organs, and 5 patients received DCD organs. SLK recipients in the 2 groups were similar with respect to age, gender, race, body mass index, donor race, and donor body mass index. The calculated Model for End-Stage Liver Disease scores and pretransplant glomerular filtration rates were similar between the groups. DCD donors were younger and had shorter liver cold ischemia times. The median DCD donor warm ischemia time was 19.0 minutes (6.0-25.0 minutes). The recipient surgical times and hospital lengths of stay were comparable between the groups. Delayed graft function was more frequent in DCD renal allografts (80% versus 31%, P = 0.06). The 1-year graft survival rates for liver allografts (100% for the DCD group versus 94% for the DBD group) and kidney allografts (100% for the DCD group versus 94% for the DBD group) were similar. In conclusion, patients undergoing DCD SLK transplantation have comparable 1-year patient and graft survival rates and acceptable perioperative morbidity in comparison with DBD SLK transplant recipients. Although long-term outcomes remain unknown, the utilization of DCD organs for SLK transplantation should be considered a valid approach to safely expanding the donor organ pool. Liver Transpl 17:591-595, 2011. © 2011 AASLD.
Operational tolerance
Authors: Levitsky Josh
Published: January 2011

Every liver transplant (LT) center has had patients who either self-discontinue immunosuppressive (IS) therapy or are deliberately withdrawn due to a research protocol or clinical concern (ie, lymphoproliferative disorder [LPD], overwhelming infection). This is understandable because maintenance IS therapy, particularly calcineurin inhibitors (CNI), is associated with significant cost, side effects, and considerable long-term morbidity and mortality. Detrimental effects of IS therapy include increased risk of cardiovascular disease, metabolic syndrome, bone loss, opportunistic and community-acquired infections, and malignancy. In fact, LT recipients have among the highest rates of chronic kidney disease and associated mortality among all nonkidney solid organ recipients. This mortality is only ameliorated by undergoing a curative kidney transplant, usurping costs and valuable organ resources. The search for improved treatment algorithms includes trial and error CNI dose minimization, the use of alternative IS agents (antimetabolites, mammalian target of rapamycin [mTOR] inhibitors), or even complete CNI withdrawal. Yet those who are successful in achieving such operational tolerance (no immunosuppression and normal allograft function) are considered lucky. The vast majority of recipients will fail this approach, develop acute rejection or immune-mediated hepatitis, and require resumption of IS therapy. As such, withdrawal of IS following LT is not standard-of-care, leaving clinicians to currently maintain transplant patients on IS therapy for life. Nonetheless, the long-term complications of all IS therapies highlight the need for strategies to promote immunologic or operational tolerance. Clinically applicable biomarker assays signifying the potential for tolerance as well as tolerogenic IS conditioning are invariably needed if systematic, controlled rather than “hit or miss” approaches to withdrawal are considered. This review will provide an overview of the basic mechanisms of tolerance, particularly in relation to LT, data from previous IS withdrawal protocols and biomarker studies in tolerant recipients, and a discussion on the prospect of increasing the clinical feasibility and success of withdrawal. Liver Transpl, 2011. © 2011 AASLD.
Cognitive‐behavioral therapy in the schools: Bringing research to practice through effective implementation
Authors: Forman Susan G. , Barakat Nicole M.
Published: January 2011

A number of evidence‐based, cognitive‐behavioral interventions have been developed that are appropriate for use with children and adolescents in school settings. Despite the potential for these interventions to prevent or ameliorate a number of child and adolescent mental health problems, their use in schools remains low. Literature related to implementation of new programs indicates that personal, social, and organizational factors influence implementation success. What is known in general about implementation of new programs and practices, and what is known specifically about implementation of cognitive‐behavioral interventions in schools, is reviewed. An examination of existing studies on implementation of cognitive‐behavioral interventions in schools indicates that five factors have been found most frequently to influence implementation success: school organizational structure; program characteristics; fit with school goals, policies, and programs; training/technical assistance; and administrator support. © 2011 Wiley Periodicals, Inc.