bluuebunny/crossref_metadata_2025 huggingface dataset:
Change in the Presence of Residual Fit: Can Competing Frames Coexist?
Authors: Gilbert Clark G.
Published: February 2006

Opportunities associated with discontinuous change typically do not trigger organizational response until the opportunity is perceived as a threat. However, threat perception can then trigger a response that accentuates organizational rigidity. This cognitive paradox is explored using a multilevel, longitudinal case study of a newspaper organization’s response to digital publishing. The results suggest that the competing frames of threat and opportunity can coexist within the firm when it creates organizationally differentiated subunits. Such a structure minimizes the need to integrate competing frames at the subunit level, enabling different behaviors to be enacted simultaneously across different units of the firm. This differentiated organizational form places an increased burden on senior teams that have to manage the inconsistencies across subunits. Insight into the structure of competing frames has broader implications for the structure of dynamic capabilities.
The Liability of Good Reputation: A Study of Product Recalls in the U.S. Automobile Industry
Authors: Rhee Mooweon , Haunschild Pamela R.
Published: February 2006

In this paper, we explore opposing theoretical claims about how organizational reputation affects market reactions to product defects. On the one hand, good reputation could be a disadvantage because expectations about product quality are more likely to be violated by defects in highly reputed products. On the other hand, a good reputation could be an advantage because of strong inertial effects on reputation orderings. We empirically test these competing hypotheses using data on product recalls in the U.S. automobile industry from 1975 to 1999. Our results support for the idea that reputation can be an organizational liability in that highly reputed firms suffer more market penalty as a result of their product recalls. We also propose that the reputational effects are moderated by two important factors: substitutability and generalism/specialism. Our results show that having few substitutes with an equivalent level of reputation, or a focused product identity stemming from specialism, buffers the negative market reactions to product recalls. We conclude with a discussion on the implications of these results for institutional, reputation, and status theories.
Organizational Becoming as Dialogic Imagination of Practice: The Case of the Indomitable Gauls
Authors: Carlsen Arne
Published: February 2006

This paper explores the relationship between authoring of identities and organizational development through a case study of the 18-year history of a professional service firm. Drawing from process theory, narrative psychology, and practice approaches to identity, I outline a perspective on organizational becoming as dialogic imagination of practice. Conceived as such, authoring takes place as a continuous stream of suggestions of what practice is, has been, and could be, simultaneously addressing life enrichment and organizational development. Three forms of imagination of practice are identified as central in the development of the case organization: (1) the instantiating of project experiences as identity exemplars; (2) a powerful dramatizing of trajectories of practice, exemplified by use of the metaphor of the “Indomitable Gauls;” and (3) a subsequent reframing instigated by discontinuous changes in dominant activity sets. The three authoring forms are discussed in relation to organizational development and adaptation. Implications include increased attention to forward-looking authoring motives and hope, a reformulation of the identity question from “who are we?” to “what are we doing?” and a possible location of practices as belonging to stories beyond that of the organization.
A Tabu Search Algorithm for the Split Delivery Vehicle Routing Problem
Authors: Archetti C. , Speranza M. G. , Hertz A.
Published: February 2006

We describe a tabu search algorithm for the vehicle routing problem with split deliveries. At each iteration, a neighbor solution is obtained by removing a customer from a set of routes where it is currently visited and inserting it either into a new route or into an existing route that has enough residual capacity. The algorithm also considers the possibility of inserting a customer into a route without removing it from another route. The insertion of a customer into a route is done by means of the cheapest insertion method. Computational experiments are reported for a set of benchmark problems, and the results are compared with those obtained by the algorithm proposed by Dror and Trudeau.
Heuristics for Joint Decisions in Production, Transportation, and Order Quantity
Authors: Yung Kai-Leung , Tang Jiafu , Ip Andrew W. H. , Wang Dingwei
Published: February 2006

An attempt is made to tackle joint decisions in assigning production, lot size, transportation, and order quantity for single and multiple products in a production-distribution network system with multiple suppliers and multiple destinations. The approach hinges on providing an optimized solution to the joint decision model (JDM) through a two-layer decomposition (TLD) method that combines several heuristics. By combining the Lagrange multipliers and introducing a number of artificial variables into the two-layer decomposition, a Lagrange relaxation decomposition (LRD) method with heuristics is developed to solve multiproduct joint decision problems (JDM-M). Using the LRD, the JDM-M model is solved by decomposing into two subproblems in two layers. The first layer is the joint decisions in assigning production, transportation flow, and lot size (APLS-TF) using the assignment heuristic AH-M. The second layer is the joint decisions in transportation and order quantity (TOQ-M) using a revised BH heuristic. Combined with Lagrange multipliers, the APLS-TF model takes into consideration the transportation costs together with production costs when it assigns annual production among suppliers. In essence, the algorithm assigns annual production simultaneously with annual transportation flows. Simulations on different sizes of problems and problems with large variances in data have shown that the LRD is effective, and in general more effective than the TLD.
Solving Noisy, Large-Scale Fixed-Point Problems and Systems of Nonlinear Equations
Authors: Bierlaire Michel , Crittin Frank
Published: February 2006

Many complex transportation models can be formulated as fixed-point problems. Typical examples are the “equilibrium-like” models, motivated by the need to capture the interaction between the transport supply (that is, the infrastructure) and transport demand (that is, travelers’ behavior) in various ways.

In this paper, we propose a new approach for solving fixed-point problems and, equivalently, systems of nonlinear equations. It is a generalization of secant methods, and uses several previous iterates to generate a linear approximation of the nonlinear function. Although it belongs to the quasi-Newton family of methods, our algorithm is matrix free, allowing it to solve large-scale systems of equations without derivative and without any particular assumption about the structure of the problem or its Jacobian.

Computational experiments on standard problems show that this algorithm outperforms classical, large-scale quasi-Newton methods in terms of efficiency and robustness. Its numerical performances are similar to Newton-Krylov methods currently considered as the best algorithms to solve large-scale nonlinear systems of equations. Furthermore, our approach, using multiple previous iterates to build a linear approximation of the nonlinear function, exhibits robust behavior in the presence of noise in the equations, which makes it particularly well adapted to transportation problems.

We run our algorithm on a simple origin-destination (OD) matrix estimation problem and on some instances of the consistent anticipatory route guidance (CARG) problem, to illustrate the applicability of the proposed method and to show its significant superiority to the classical method of successive averages (MSA). Regarding size, we were able to solve a CARG problem with more than 120,000 variables. We were also able to solve classical problems with up to two million variables.
Slot Trading Opportunities in Collaborative Ground Delay Programs
Authors: Vossen Thomas W. M. , Ball Michael O.
Published: February 2006

The Federal Aviation Administration (FAA) and the major airlines in the United States have embraced a new initiative to improve air traffic flow management. This initiative, called collaborative decision making (CDM), is based on the recognition that improved data exchange and communication between the FAA and the airlines will lead to better decision making. In particular, the CDM philosophy emphasizes that decisions with a potential economic impact on airlines should be decentralized and made in collaboration with the airlines whenever possible.

The CDM paradigm has led to fundamental changes in the implementation of ground delay programs. A key component has been the introduction of the compression procedure, which allows for the exchange of arrival slots between airlines. In this paper, we consider opportunities for increased airline control by interpreting the compression procedure as a mediated slot trading mechanism. Based on this interpretation, we propose an extension that allows airlines to submit so-called at-least, at-most offers. We develop an efficient integer programming model to solve the mediator’s problem, and show that the resulting mechanism can substantially improve the ability of airlines to optimize their internal cost functions.
A Transportation Problem with Minimum Quantity Commitment
Authors: Lim Andrew , Wang Fan , Xu Zhou
Published: February 2006

We study a transportation problem with the minimum quantity commitment (MQC), which is faced by a famous international company. The company has a large number of cargos for carriers to ship to the United States. However, the U.S. Marine Federal Commission stipulates that when shipping cargos to the United States, shippers must engage their carriers with an MQC. With such a constraint of MQC, the transportation problem becomes intractable. To solve it practically, we provide a mixed-integer programming model defined by a number of strong facets. Based on this model, a branch-and-cut search scheme is applied to solve small-size instances and a linear programming rounding heuristic for large ones. We also devise a greedy approximation method, whose solution quality depends on the scale of the minimum quantity if the transportation cost forms a distance metric. Extensive experiments have been conducted to measure the performance of the formulations and the algorithms and have shown that the linear rounding heuristic behaves best.
Dynamic Column Generation for Dynamic Vehicle Routing with Time Windows
Authors: Chen Zhi-Long , Xu Hang
Published: February 2006

We consider a dynamic vehicle routing problem with hard time windows, in which a set of customer orders arrives randomly over time to be picked up within their time windows. The dispatcher does not have any deterministic or probabilistic information on the location and size of a customer order until it arrives. The objective is to minimize the sum of the total distance of the routes used to cover all the orders. We propose a column-generation-based dynamic approach for the problem. The approach generates single-vehicle trips (i.e., columns) over time in a real-time fashion by utilizing existing columns, and solves at each decision epoch a set-partitioning-type formulation of the static problem consisting of the columns generated up to this time point. We evaluate the performance of our approach by comparing it to an insertion-based heuristic and an approach similar to ours, but without computational time limit for handling the static problem at each decision epoch. Computational results on various test problems generalized from a set of static benchmark problems in the literature show that our approach outperforms the insertion-based heuristic on most test problems.
Planning for Robust Airline Operations: Optimizing Aircraft Routings and Flight Departure Times to Minimize Passenger Disruptions
Authors: Lan Shan , Clarke John-Paul , Barnhart Cynthia
Published: February 2006

Airlines typically construct their schedules assuming that every flight leg will depart and arrive as planned. Because this optimistic scenario rarely occurs, these plans are frequently disrupted and airlines often incur significant costs in addition to those originally planned. Flight delays and schedule disruptions also cause passenger delays and disruptions. A more robust plan can reduce the occurrence and impact of these delays, thereby reducing costs. In this paper, we present two new approaches to minimize passenger disruptions and achieve robust airline schedule plans. The first approach involves routing aircraft, and the second involves retiming flight departure times.

Because each airplane usually flies a sequence of flight legs, delay of one flight leg might propagate along the aircraft route to downstream flight legs and cause further delays and disruptions. We propose a new approach to reduce delay propagation by intelligently routing aircraft. We formulate this problem as a mixed-integer programming problem with stochastically generated inputs. An algorithmic solution approach is presented. Computational results obtained using data from a major U.S. airline show that our approach can reduce delay propagation significantly, thus improving on-time performance and reducing the numbers of passengers disrupted.

Our second area of research considers passengers who miss their flight legs due to insufficient connection time. We develop a new approach to minimize the number of passenger misconnections by retiming the departure times of flight legs within a small time window. We formulate the problem and an algorithmic solution approach is presented. Computational results obtained using data from a major U.S. airline show that this approach can substantially reduce the number of passenger misconnections without significantly increasing operational costs.
A Stochastic Programming Approach to the Airline Crew Scheduling Problem
Authors: Yen Joyce W. , Birge John R.
Published: February 2006

Traditional methods model the billion-dollar airline crew scheduling problem as deterministic and do not explicitly include information on potential disruptions. Instead of modeling the crew scheduling problem as deterministic, we consider a stochastic crew scheduling model and devise a solution methodology for integrating disruptions in the evaluation of crew schedules. The goal is to use that information to find robust solutions that better withstand disruptions. Such an approach is important because we can proactively consider the effects of certain scheduling decisions. By identifying more robust schedules, cascading delay effects are minimized. In this paper we describe our stochastic integer programming model for the airline crew scheduling problem and develop a branching algorithm to identify expensive flight connections and find alternative solutions. The branching algorithm uses the structure of the problem to branch simultaneously on multiple variables without invalidating the optimality of the algorithm. We present computational results demonstrating the effectiveness of our branching algorithm.
Quantification of mRNA in Whole Blood by Assessing Recovery of RNA and Efficiency of cDNA Synthesis
Authors: Mitsuhashi Masato , Tomozawa Shigeru , Endo Katsuya , Shinagawa Atsushi
Published: February 2006

Background: Current gene expression analysis relies on the assumption that the isolated RNA represents all species of mRNA in proportions equal to those in the original materials. No system is available for absolute quantification of mRNA.

Methods: We applied whole blood to 96-well filterplates to trap leukocytes. Lysis buffer containing cocktails of specific reverse primers and known concentrations of synthetic external control RNA (RNA34) was added to filterplates, and cell lysates were transferred to oligo(dT)-immobilized microplates for hybridization. We then synthesized the cDNA in the oligo(dT)-immobilized microplates from these primer sites and used the cDNA for real-time PCR. RNA34 acted as a universal control, and gene amplification results were converted to quantities of mRNA per microliter of whole blood after the recovery of RNA34 in each sample was determined.

Results: Under fully optimized conditions, both added RNA34 and native mRNA species exhibited ∼10% recovery from whole blood to real-time PCR. When whole blood was stimulated ex vivo, changes in gene expression as low as 30%–40% were detected with statistical significance, and the experimental CVs were low (10%–20%).

Conclusion: This new system to estimate mRNA copies per microliter of whole blood may allow standardization of gene-expression–based molecular diagnostics.
Variations in Porphobilinogen and 5-Aminolevulinic Acid Concentrations in Plasma and Urine from Asymptomatic Carriers of the Acute Intermittent Porphyria Gene with Increased Porphyrin Precursor Excretion
Authors: Floderus Ylva , Sardh Eliane , Möller Christer , Andersson Claes , Rejkjaer Lillan , Andersson Dan EH , Harper Pauline
Published: February 2006

Background: The heme precursors porphobilinogen (PBG) and 5-aminolevulinic acid (ALA) accumulate during overt crises of acute intermittent porphyria (AIP), and high excretion of these metabolites often continues in the asymptomatic phase.

Methods: We measured concentrations of PBG and ALA and investigated the correlation between these metabolites in plasma and urine in 10 asymptomatic AIP carriers with high excretion and in 5 healthy individuals. We quantified plasma concentrations with an HPLC–mass spectrometric method and urine concentrations with ion-exchange chromatography.

Results: The mean (SD) plasma concentrations of PBG and ALA in the AIP carriers were 3.1 (1.0) and 1.7 (0.7) μmol/L, respectively. The mean 8-h urinary excretion amounts of PBG and ALA in the AIP carriers were 102 (25) and 56 (18) μmol, respectively, whereas the corresponding values for healthy individuals were 2.9 (0.7) and 9.3 (1.2) μmol. The correlations between PBG and ALA values in plasma and urine of the AIP carriers were 0.678 and 0.856, respectively. The mean PBG/ALA ratio was ∼2.0 in both plasma and urine for the AIP carriers and 0.3 in urine for the healthy individuals. The renal clearance rates for PBG and ALA were 71 (15) and 70 (13) mL/min, respectively.

Conclusions: The described HPLC-mass spectrometric method enabled characterization of variations in plasma PBG and ALA in AIP carriers during an 8-h period. The renal clearances were similar for both metabolites. This method could be used to monitor AIP patients during treatment.
B-Type Natriuretic Peptide (BNP) and N-Terminal Pro-BNP in Obese Patients without Heart Failure: Relationship to Body Mass Index and Gastric Bypass Surgery
Authors: St. Peter John V , Hartley Guilford G , Murakami MaryAnn M , Apple Fred S
Published: February 2006

Background: Further investigations are warranted to better characterize variables that may confound the clinical interpretation of plasma natriuretic peptide measurements, which are increasingly recognized to have diagnostic and predictive importance.

Methods: Blood samples (EDTA plasma) from patients (n = 206) attending clinics for the medical treatment and follow-up of obesity were analyzed for B-type natriuretic peptide (BNP; Bayer assay) and the N-terminal segment of its prohormone (NT-proBNP; Roche assay). Natriuretic peptide concentration ranges were evaluated in those without diagnosis of congestive heart failure (CHF) or chronic kidney disease (CKD).

Results: BNP and NT-proBNP were directly correlated (r = 0.87; P = 0.01), with NT-proBNP concentrations higher relative to BNP. Of obese patients without CHF or CKD, 21.6% (40 of 185) had NT-proBNP concentrations greater than the published assay upper reference limit. Concentrations of both natriuretic peptides were higher in patients currently exposed to beta blockers, patients with the diagnosis of hypertension or type 2 diabetes, and patients with a history of gastric bypass surgery. An inverse relationship between body mass index (BMI) and both BNP and NT-proBNP was evident. According to the National Institutes of Health, National Heart, Lung, and Blood Institute classification, more than 95% of the participants sampled in this study were either obesity class 2 (35 kg/m2 < BMI < 39.9 kg/m2) or class 3 (BMI ≥40 kg/m2)

Conclusions: A substantial proportion of obese patients without CHF or CKD have concentrations greater than the upper reference limit for NT-proBNP but not for simultaneously measured BNP. A history of gastric bypass surgery appeared to be a significant predictor of increased natriuretic peptide concentrations when assessed in a population of patients with class 2 or 3 obesity.
Mechanisms in Protein O-Glycan Biosynthesis and Clinical and Molecular Aspects of Protein O-Glycan Biosynthesis Defects: A Review
Authors: Wopereis Suzan , Lefeber Dirk J , Morava Éva , Wevers Ron A
Published: February 2006

Background: Genetic diseases that affect the biosynthesis of protein O-glycans are a rapidly growing group of disorders. Because this group of disorders does not have a collective name, it is difficult to get an overview of O-glycosylation in relation to human health and disease. Many patients with an unsolved defect in N-glycosylation are found to have an abnormal O-glycosylation as well. It is becoming increasingly evident that the primary defect of these disorders is not necessarily localized in one of the glycan-specific transferases, but can likewise be found in the biosynthesis of nucleotide sugars, their transport to the endoplasmic reticulum (ER)/Golgi, and in Golgi trafficking. Already, disorders in O-glycan biosynthesis form a substantial group of genetic diseases. In view of the number of genes involved in O-glycosylation processes and the increasing scientific interest in congenital disorders of glycosylation, it is expected that the number of identified diseases in this group will grow rapidly over the coming years.

Content: We first discuss the biosynthesis of protein O-glycans from their building blocks to their secretion from the Golgi. Subsequently, we review 24 different genetic disorders in O-glycosylation and 10 different genetic disorders that affect both N- and O-glycosylation. The key clinical, metabolic, chemical, diagnostic, and genetic features are described. Additionally, we describe methods that can be used in clinical laboratory screening for protein O-glycosylation biosynthesis defects and their pitfalls. Finally, we introduce existing methods that might be useful for unraveling O-glycosylation defects in the future.
Stochastische, rekursive Weichenklassifikation zur gleisselektiven Ortung von Schienenfahrzeugen (Stochastic, Recursive Turnout Classification for Track-selective Location of Rail Vehicles)
Authors: Geistler Alexander , Böhringer Frank
Published: February 2006

Bei der sicherheitstechnisch relevanten Anwendung bordautonomer Ortungssysteme im Eisenbahnwesen ist die gleisgenaue Ortung, z. B. in Bahnhöfen oder auf zwei- und mehrgleisigen Strecken, eine elementare Forderung. Mit Wirbelstrom-Sensoren können Eisenbahnweichen detektiert und klassifiziert werden, um diese Forderung zu erfüllen. Die statistische Bewertung der Klassifikation geschieht mit dem Modell eines Bayes-Klassifikators. Die Zuordnung der geschätzten Position zu einem Gleis erfolgt dann mittels eines Markov-Modells. Erste erfolgversprechende Versuchsergebnisse zeigen die Robustheit der propagierten Methode.
Innovative Dämpferkonzepte für moderne Hochleistungslokomotiven (Innovative Damper Concepts for Modern High-performance Locomotives)
Authors: Breuer Werner
Published: February 2006

Die Achslasten moderner Hochleistungslokomotiven nähern sich immer mehr den Grenzwerten. Dies zieht Einschränkungen bei der Zulassung und im Betrieb nach sich. Siemens Transportation Systems hat daher zwei neuartige Dämpferkonzepte entwickelt: Den aktiven Drehdämpfer, der die Zulassungsfähigkeit garantiert, und den frequenzgeregelten Vertikaldämpfer, der die Oberbaubelastung nachhaltig reduziert.
Potenziale aktiver und semiaktiver Skyhook-Regelgesetze in der Sekundärfederstufe von Schienenfahrzeugen (Potentials of Active and Semiactive Skyhook Control Laws applied to the Secondary Suspensions of Railway Vehicles)
Authors: Hohenbichler Norbert , Six Klaus
Published: February 2006

Im vorliegenden Beitrag wird das Potenzial nach dem Skyhook-Gesetz hochdynamisch geregelter aktiver und semiaktiver Fahrwerksregelungen in der Sekundärfederstufe von Schienenfahrzeugen hinsichtlich Fahrkomfort und unter Berücksichtigung der resultierenden Federwege untersucht. Es wird eine systematische Vorgehensweise vorgestellt, die es ermöglicht, einen sinnvollen Vergleich zwischen passiven und aktiven Systemen zu führen. Die Untersuchungen zeigen, dass der Komfortgewinn der untersuchten Skyhook-Konzepte auf dem betrachteten Fahrweg bei idealer Sensorik, Aktorik und Signalverarbeitung aufgrund der deterministischen Trassierung nicht mehr als 10% beträgt.
Prevalence of Necrotizing Hepatopancreatitis in Female Broodstock of White Shrimp Penaeus vannamei with Unilateral Eyestalk Ablation and Hormone Injection
Authors: Morales Covarrubias M. S. , Osuna-Duarte A. G. , Garcia-Gasca A. , Lightner D. V. , Mota-Urbina J. C.
Published: February 2006

The present study analyzed the relationship between unilateral eyestalk ablation and steroid hormone injection in female white shrimp Penaeus vannamei, the prevalence of necrotizing hepatopancreatitis (NHP) caused by the intracellular rickettsia-like bacterium NHP-B. Two simultaneous bioassays determined the onset and development of NHP in broodstock. Wet-mount analysis, conventional histopathology, and in situ hybridization with an NHP-B-specific DNA probe were used to assess the prevalence and degree of severity of NHP and to confirm NHP-B infection. Wet-mount and histopathological results showed that females with unilateral eyestalk ablation had a 64% prevalence of NHP at grades 2 and 4, while females receiving the hormone injection showed a 23% prevalence of NHP at grades 3 and 4; control shrimp injected with phosphate-buffered saline (PBS) displayed a 9% prevalence of NHP at grade 3, whereas nonablated controls showed no signs of disease. The rickettsia-like specific DNA probe demonstrated a positive hybridization signal in NHP-B, and the hepatopancreas, the target tissue for the bacterium, showed a strong positive signal. Significant differences (P < 0.05) were found in females with unilateral eyestalk ablation compared with nonablated controls, in hormone-injected females compared with PBS-injected controls, and in females with unilateral eyestalk ablation compared with the hormone injection group. We conclude that unilateral eyestalk ablation enhances NHP disease prevalence in broodstock reared under maturation conditions.
Susceptibility of Koi Carp, Common Carp, Goldfish, and Goldfish × Common Carp Hybrids to Cyprinid Herpesvirus-2 and Herpesvirus-3
Authors: Hedrick Ronald P. , Waltzek Thomas B. , McDowell Terry S.
Published: February 2006

Hybrid goldfish (male goldfish Carassius auratus × female common carp Cyprinus carpio) were completely resistant to mortality following experimental infections with cyprinid herpesvirus-2 (CyHV-2) and moderately resistant to cyprinid herpesvirus-3 (CyHV-3). In contrast, examination of the parental species demonstrated that goldfish were highly susceptible to CyHV-2 infections and that both common carp and koi (a variant of common carp) were highly susceptible to CyHV-3. Approximately 50% of the hybrids examined at 25 d after intraperitoneal injection with either CyHV-2 or CyHV-3 possessed viral genomic DNA, as detected by polymerase chain reaction assays. These initial trials suggest that hybrid goldfish have a natural resistance to mortality following experimental challenge with CyHV-2 and CyHV-3. However, additional studies that examine virus replication, including the potential for the development of a carrier state in hybrids, are needed. The production of hybrids for the food fish market may represent one means of avoiding the severe and negative impacts of the disease associated with CyHV-3.
Successful Stem Cell Therapy Using Umbilical Cord Blood-Derived Multipotent Stem Cells for Buerger's Disease and Ischemic Limb Disease Animal Model
Authors: Kim Sung-Whan , Han Hoon , Chae Gue-Tae , Lee Sung-Hoon , Bo Sun , Yoon Jung-Hee , Lee Yong-Soon , Lee Kwang-Soo , Park Hwon-Kyum , Kang Kyung-Sun
Published: February 2006

Buerger's disease, also known as thromboangiitis obliterans, is a nonatherosclerotic, inflammatory, vasoocclusive disease. It is characterized pathologically as a panangiitis of medium and small blood vessels, including both arteries and adjacent veins, especially the distal extremities (the feet and the hands). There is no curative medication or surgery for this disease. In the present study, we transplanted human leukocyte antigen-matched human umbilical cord blood (UCB)-derived mesenchymal stem cells (MSCs) into four men with Buerger's disease who had already received medical treatment and surgical therapies. After the stem cell transplantation, ischemic rest pain suddenly disappeared from their affected extremities. The necrotic skin lesions were healed within 4 weeks. In the follow-up angiography, digital capillaries were increased in number and size. In addition, vascular resistance in the affected extremities, compared with the preoperative examination, was markedly decreased due to improvement of the peripheral circulation. Because an animal model of Buerger's disease is absent and also to understand human results, we transplanted human UCB-derived MSCs to athymic nude mice with hind limb ischemia by femoral artery ligation. Up to 60% of the hind limbs were salvaged in the femoral artery-ligated animals. By in situ hybridization, the human UCB-derived MSCs were detected in the arterial walls of the ischemic hind limb in the treated group. Therefore, it is suggested that human UCB-derived MSC transplantation may be a new and useful therapeutic armament for Buerger's disease and similar ischemic diseases.
In Vitro Culture During Retroviral Transduction Improves Thymic Repopulation and Output After Total Body Irradiation and Autologous Peripheral Blood Progenitor Cell Transplantation in Rhesus Macaques
Authors: Loré Karin , Seggewiss Ruth , Guenaga F. Javier , Pittaluga Stefania , Donahue Robert E. , Krouse Allen , Metzger Mark E. , Koup Richard A. , Reilly Cavan , Douek Daniel C. , Dunbar Cynthia E.
Published: February 2006

Immunodeficiency after peripheral blood progenitor cell (PBPC) transplantation may be influenced by graft composition, underlying disease, and/or pre-treatment. These factors are difficult to study independently in humans. Ex vivo culture and genetic manipulation of PBPC grafts may also affect immune reconstitution, with relevance to gene therapy applications. We directly compared the effects of three clinically relevant autologous graft compositions on immune reconstitution after myeloblative total body irradiation in rhesus macaques, the first time these studies have been performed in a large animal model with direct clinical relevance. Animals received CD34+ cell dose-matched grafts of either peripheral blood mononuclear cells, purified CD34+ PBPCs, or purified CD34+ PBPCs expanded in vitro and retrovirally transduced. We evaluated the reconstitution of T, B, natural killer, dendritic cells, and monocytes in blood and lymph nodes for up to 1 year post-transplantation. Animals receiving selected-transduced CD34+ cells had the fastest recovery of T-cell numbers, along with the highest T-cell-receptor gene rearrangement excision circles levels, the fewest proliferating Ki-67+ T-cells in the blood, and the best-preserved thymic architecture. Selected-transduced CD34+ cells may therefore repopulate the thymus more efficiently and promote a higher output of naïve T-cells. These results have implications for the design of gene therapy trials, as well as for the use of expanded PBPCs for improved T-cell immune reconstitution after transplantation.
Three-dimensional lower-bound solutions for the stability of plate anchors in sand
Authors: Merifield R. S. , Lyamin A. V. , Sloan S. W.
Published: February 2006

Soil anchors are commonly used as foundation systems for structures that require uplift or lateral resistance. These types of structure include transmission towers, sheet pile walls and buried pipelines. Although anchors are typically complex in shape (e.g. drag or helical anchors), many previous analyses idealise the anchor as a continuous strip under plane strain conditions. This assumption provides numerical advantages, and the problem can be solved in two dimensions. In contrast to recent numerical studies, this paper applies three-dimensional numerical limit analysis and axisymmetrical displacement finite element analysis to evaluate the effect of anchor shape on the pullout capacity of horizontal anchors in sand. The anchor is idealised as either square or circular in shape. Results are presented in the familiar form of break-out factors based on various anchor shapes and embedment depths, and are also compared with existing numerical and empirical solutions.
Globalization and Stock Market Returns
Authors: Lam Swee Sum , Ang William Wee-Lian
Published: February 2006

With increasing globalization, to what extent do stock market returns reflect global or domestic risk factors? We find a significant relationship between stock market returns and the global market risk factor and macroeconomic factors respectively. In particular, global factors offer four times more explanatory power than domestic factors for developed market stock returns. Yet domestic factors are as important as global ones in emerging economies. Our method allows for the proxies of the state variables to be endogenously determined. The relationship between macroeconomy and stock market returns is robust after accounting for the market factor, firm size and book-to-market characteristics.
Special Interest Politics and Endogenous Lobby Formation
Authors: Laussel Didier G
Published: February 2006

We analyze endogenous lobby formation within a slightly modified version of the "special interest politics" model of Persson (1998). In our model the interest groups hold different fixed endowments of an "infrastructure good" which is a complement in consumption of the local public good. For any fixed set of organized groups the lobbying game is shown to have a unique equilibrium if the cost-elasticity of the supply of public good to the interest groups by the government is not too large. The groups which benefit from larger infrastructure endowments are then proved to be the ones which become organized while the others remain unorganized.
Citizen Candidacy With Asymmetric Information
Authors: Casamatta Georges , Sand-Zantman Wilfried
Published: February 2006

We extend a simple version of the citizen candidacy model (developed by Osborne-Slivinski (1996) and Besley-Coate (1997)) to an asymmetric information setting, in which the type of a given individual is assumed to be private information. Focusing on a particular class of perfect Bayesian equilibria, we show that there exist only two kinds of equilibria. In the first one, both non-median types become candidates and those equilibria generalize to any number of (potential) candidates. In the second one, only one of the non-median types chooses to become candidates for the election and those equilibria hold for a number of (potential) candidates at most equal to 3. This is in sharp contrast with the complete information framework in which only the median type individuals stand for office when the entry cost is sufficiently low.
Likely Events and Possible States
Authors: Lo Kin Chung
Published: February 2006

This paper provides a recipe to generate definitions of possibility, which is equivalent to the standard approach of deriving possibility from belief/knowledge. Savage's notion of nonnullity is therefore an example that fits into our framework. The recipe is used to create a new definition of possibility, which is logically coherent for all weakly monotonic preferences. For various nonexpected utility models of preference, our new definition improves nonnullity and its existing alternatives.
The Impact of Delivery Synergies on Bidding in the Georgia School Milk Market
Authors: Marshall Robert C. , Raiff Matthew E. , Richard Jean-Francois , Schulenberg Steven P.
Published: February 2006

Each summer milk processors around the country participate in sealed bid procurements for the right to provide public schools with milk throughout the subsequent academic year. School district contracts are an important part of vehicle routing problems that milk processors solve on an ongoing basis. There are allegedly substantial cost savings for a milk processor from servicing a district that is directly adjacent to one they already service. In this paper, following the work of Krishna and Rosenthal (1996), we construct a procurement model allowing for cost synergies. The equilibrium bid function maps directly into an empirical specification. Using data from a time period when bidders were allegedly acting non-cooperatively, our structural parametric estimation results give significant support for the presence of cost synergies in the bidding.
Mathematical Modeling of the Transient Behaviour of a Chemostat Undergoing Bio-Desulfurization of Model Organosulfur Compounds and Diesel Using Pure and Isolated Bacterial Strains
Authors: Chowdhury Ranjana , Duttagupta Anindita
Published: February 2006

Bio-desulfurization of model organosulfur compounds, namely alkylated dibenzothiophene (DBT) and diesel oil was conducted in a laboratory scale fermenter using pure and isolated bacterial strains namely, Rhodococcus sp. (NCIM-2891) and Rhodococcus sp. JUBDS1 respectively. The diesel used as the feedstock was previously hydrodesulfurized up to a total sulfur content of 300-500 ppm. The Sulphur concentration of product stream of diesel from the process lies in the range of 10-15 ppm. Alkylated dibenzothiophenes were used in pure forms. During the study of chemostat in batch mode the initial substrate concentration of organosulfur compounds, the sulfur concentration in diesel, the stirring speed, temperature, oil to aqueous phase ratio, etc., were varied as parameters. The intrinsic kinetic parameters of bacterial growth like maximum specific growth, mmax, half saturation constant, and KS were determined by carrying out experiments in Erlenmeyer flasks using suitable medium and subsequent non-linear regression analysis. A mathematical model showing the transient behavior of chemostat was developed. Simulated data were compared with the experimental findings to validate the model developed.
Towards Bifurcation Detection in Kinetic Monte Carlo Simulations: Robust Identification with Artificial Neural Networks and Nonlinear Kalman Filters
Authors: González-Figueredo Carlos , Rico-Martínez Ramiro
Published: February 2006

The efficient characterization of the nonlinear dynamical response of kinetic molecular simulations is discussed. Following ideas originally proposed by Kevrekidis et al. [1, 2], one can empower molecular simulations as model-free equations and use them as a reference to perform bifurcation detection. Such a procedure requires the use of trajectories from the molecular simulation to generate low-order models (e.g. polynomial) that allow one to infer the location of a bifurcation. If such identification step can be performed robustly, a feedback control policy that drives the molecular simulation to the bifurcation point can be constructed. In previous work, the identification of the low-order model has been singled out as the key element in handling noise trajectories, such as those generated by low-resolution molecular simulations. Here, a procedure motivated by the use of Kalman Filter observers is proposed as a means to give robustness to the identification procedure. The potential of the technique to characterize the dynamical response of kinetic molecular simulations is illustrated using examples related to the CO oxidation over a catalytic surface.
Stability Analysis of an Activated Sludge Bioreactor at a Petrochemical Plant at Different Temperatures
Authors: Martínez Sergio A. , Rodríguez Miriam G. , Morales Miguel A.
Published: February 2006

The Mexican petrochemical industry, Morelos S.A. de C.V. is one of the biggest and most important petroleum industries in Mexico and in Latin America. It has an activated sludge system to treat its wastewater flow, which is about 7000m3/d. The wastewater contains volatile organic carbon substances classified as toxic. The old surface aeration system was changed for fine bubble diffusers; however, one major drawback of the new aeration system is that the temperature in the bioreactor has increased due to the compression of the air, which at the compressor exit reaches up to 85oC. This effect produces a temperature in the aerated bioreactor of 32oC during the fall, whereas in the spring and summer, the bioreactor temperature reaches higher values than 40oC. The high temperatures reduce the microorganisms activity and cause higher volatilization rates of volatile compounds, among other effects, which affect the performance of the biological treatment. In this work we performed a stability analysis at different equilibrium points in different scenarios of temperatures, recycle flowrate and wastage flowrate. The eigenvalues of the state matrix of dynamical model of the petrochemical wastewater treatment were evaluated. The model describes the effect of the temperature on the soluble and volatile pollutants removal rate, heterotrophic organism growth rate, oxygen uptake rate and biomass concentration in the settler. The model was obtained from tests that were done in laboratory reactors with 14 L of capacity, which were operated at different temperatures (from 30oC to 45oC), with the same conditions as the actual system. Simulations were done based on the model obtained manipulating the operation variables Qw and Qr. The stability analysis was also done to the reactor without recycle (Qr = 0 m3/d). In all the cases the stability analyses was performed. The stripping of VOC´s is an important process of COD removal at high operation temperatures.
Dehydrogenation of Ethane and Hydrogenation of Carbon Dioxide in a Catalytic Membrane Reactor Using Copper-Plated LaNi5 as a Membrane Material
Authors: Uemura Yoshimitsu , Morita Kazuyuki , Ohzuno Yoshihiro , Hatate Yasuo
Published: February 2006

A membrane reactor consisting of a reactor and a separation membrane may be suitable to provide hydrogen from hydrocarbon in order to reduce carbon dioxide. In this study, a catalytic membrane reactor, a type of membrane reactor, was designed and tested to prove if both the reactions (dehydrogenation of ethane, and reduction of carbon dioxide to carbon monoxide) occur on each side of the membrane in the reactor as expected. As membrane materials, copper-plated LaNi5 and CaNi5 were chosen. In the first step, lower hydrocarbons including ethane was dehydrogenated at one side of the membrane; another side was swept by an inert gas. In the second step, simultaneous feed of ethane (one side) and carbon dioxide (another side) was tried if both the reactions (dehydrogenation of ethane and reduction of carbon dioxide) occur. Carbon dioxide was reduced to carbon monoxide; ethane was dehydrogenated to give ethene.
Plasma-Prepared Ni/Al2O3: Preparation, Characterization and Toluene Hydrogenation
Authors: Ding Lianhui , Zhang Zisheng Jason , Zheng Ying , Zhang Zhikun , Ring Zbigniew , Chen Jinwen
Published: February 2006

Nano-nickel particles were prepared using hydrogen arc plasma method and new nano-nickel hydrogenation catalysts were prepared through calcinating mixtures of the plasma-prepared nano-nickel particles and a ?-alumina support. The catalysts were characterized by using SEM, XRD, and TPR. The activities of the catalysts were evaluated through the hydrogenation of toluene in a fixed be microreactor. Catalysts prepared by conventional comulling and impregnation methods were also examined for comparative purposes. The characterization results showed that the nano-nickel catalysts had an egg-shell structure in terms of nickel-alumina distribution, with most of the nickel located at the outer surface of the catalyst particles. The hydrogenation experiments showed that the nano-nickel catalyst provided much higher activities than those co-precipitated and impregnated nickel catalysts with similar nickel contents. However, both types of catalysts followed first-order reaction kinetics and similar activation energies were observed.
Optimization of Bacterial Oxidation Process Parameters for Selective Leaching of Nickel by Thiobacillus Ferrooxidans
Authors: Pogaku Ravindra , Kodali Bharathi
Published: February 2006

Nickel bioleaching from copper flotation concentrate assumes greater significance because of its value and not many studies are carried out in these lines. Hence, nickel leaching was attempted and several process parameters of bacterial oxidation for copper flotation concentrate were examined for optimization. The parameters considered for shake flask leaching experiments were temperature, pulp density, particle size, agitation, residence time and inoculum size. The effect of variable proportions of each parameter on nickel leachability was studied. Optimum values of pulp density (10%) and agitation (140 rpm) played an important role in controlling the mass transfer resistance during leaching process. Increase in temperature from 27oC to 30oC has accelerated the bacterial oxidation process while initial concentration of inoculum (1-10%) has not shown considerable variation in nickel leachability. A particle size of ±60#size was found to be essential for bacterial attack. Maintenance of optimum conditions of leaching has yielded considerable nickel recovery (55%) compared to low recovery under unoptimal conditions.
Flow Induced by Dual-Turbine of Different Diameters in a Gas-Liquid Agitation System: the Agitation and Turbulence Indices
Authors: Garcia-Cortes Daniel , Xuereb Catherine , Taillandier Patricia , Jauregui-Haza Ulises J , Bertrand Joel
Published: February 2006

Flow induced by a dual turbine stirred tank was characterized measuring local velocities with a LDV and drawing the main velocity fields and the maps of turbulence intensities. The hydrodynamic regime studied in all the experiments was the so-called merging flow regime. Two impeller configurations were studied. In the first one, two disk style turbine of the same dimensions (configuration A) were used, while in the second one, the dimensions of the upper turbine were 20 % proportionally smaller than those of the lower turbine (configuration B). The agitation and turbulence indices were used to evaluate, as a first order approximation, the power consumption distribution between convective and turbulent flows. The comparison of the two-phase agitation systems studied showed that configuration B seems to be more efficient than configuration A, since both induce a similar global convective flow, but the first one assures a significant reduction of power consumption. The distribution of power consumption between convective and turbulent flows was evaluated using the agitation index and a new global parameter: turbulence index.