bluuebunny/crossref_metadata_2025 huggingface dataset:
Long-term Follow-up and Knee Osteoarthritis Change after Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Dislocation
Authors: Nomura Eiki , Inoue Motoyasu , Kobayashi Shigeru
Published: August 2007

Background

Proximal or distal realignment procedures have long been selected as treatment for recurrent patellar dislocation, but associated knee osteoarthritis has been a substantial problem that leads to poor results. A new approach, medial patellofemoral ligament reconstruction, has recently started, but there have been no reports on the long-term follow-up.

Hypothesis

Anatomical medial patellofemoral ligament reconstruction can lead to satisfactory long-term outcome and a low association rate of knee osteoarthritis.

Study Design

Case series; Level of evidence, 4.

Methods

Twenty-four knees from 22 patients who underwent medial patellofemoral ligament reconstruction for recurrent patellar dislocation were reviewed at a mean follow-up of 11.9 years (range, 8.5-17.2 years). A lateral release was done on 14 of 24 knees. The clinical/physical outcome and the association of knee osteoarthritis were investigated. Patellofemoral and femorotibial osteoarthritis on the radiographs was evaluated using the Crosby/Insall and the Kellgren/Lawrence grading systems.

Results

According to the Crosby/Insall criteria, 11 knees (46%) were classified as excellent, 10 (42%) as good, 3 (12%) as fair/poor, and none as worse at follow-up. Further lateral subluxation or dislocation occurred in only 2 knees. The mean Kujala score improved significantly from 63.2 points preoperatively to 94.2 points at follow-up (P < .0001). According to the Crosby/Insall grading system, patellofemoral osteoarthritis was none to mild in 23 of the 24 knees and moderate in 1 knee, preoperatively. At the final follow-up, 21 knees were none to mild, and 3 knees were moderate. There were only 2 knees that had definite progression from none to mild to a moderate grade.

Conclusion

The association of definite knee osteoarthritis in medial patellofemoral ligament reconstruction with or without lateral release was small in the long-term follow-up. The conclusion is that medial patellofemoral ligament reconstruction not only prevents further patellar dislocation but also shows no or only slight progression of knee osteoarthritis.
Spirituality and Health in Punjabi Sikh
Authors: Labun Evelyn , Emblen Julia D.
Published: August 2007

The purpose of this study was to examine the interrelationship of health, illness, and spirituality for Punjabi Sikh living in Canada. A grounded theory study with a convenience sample and use of snowballing technique provided a sample of 15 participants ranging in age from 20 to 70 years. Constant comparative method with dimensional analysis was used to analyze the data beginning with the first interview. The themes of being healthy and looking for the spiritual are described. Looking for the spiritual results in the person becoming spiritually strong and therefore being healthier, recovering from illness, or having the ability to feel comfortable when near death. Nurses who understand the interplay of spirituality and health can support Punjabi Sikh in their food requirements, prayers, and feelings of hope and anguish during illness or life transitions.
Pre-service professionals' constructs of adolescent risk-taking and approaches to risk management
Authors: Abbott-Chapman Joan , Denholm Carey , Wyld Colin
Published: August 2007

The research explored constructs of potentially harmful adolescent risk-taking of 220 university students in their final year of degree courses in education, law, medicine, nursing, psychology and social work, who anticipated they would be dealing with young people professionally. Their personal risk hierarchies, and their own experience of risk-taking when they were teenagers, were investigated as potential influences upon the normative orientations of their future professional roles, expressed in their support for varying social policy options including zero tolerance and harm minimization. Findings suggest that their commitment to underlying value positions regarding risk-taking and risk-management were not significantly related to gender, age or personal risk-taking profiles but to professional socialization in their degree course. The implications of respondents' preferred ways of dealing with adolescent risk-taking as compared to young people's choices for themselves are explored, along with concepts of risk management in current policy frameworks.
Educational provision for refugee youth in Australia: left to chance?
Authors: Sidhu Ravinder , Taylor Sandra
Published: August 2007

This article investigates how education bureaucracies in Australia use languages of categorization and promote community partnerships to construct and govern the refugee subject. We use a framework of governmentality to analyse education policies and statements emerging from two levels of government — Commonwealth and state. Drawing on web-based materials, policy statements and accounts of parliamentary debates, the article documents the ways in which refugee education continues to be subsumed within broader education policies and programmes concerned with social justice, multiculturalism and English language provision. Such categorizations are premised on an undifferentiated ethnoscape that ignores the significantly different learning needs and sociocultural adjustments faced by refugee students compared with migrants and international students. At the same time, educational programmes of inclusion that are concerned with utilizing community organizations to deliver services and enhance participation, point to the emergence of `government through community partnerships' — a mode of governance increasingly associated with advanced liberal societies.
Acquired hematopoietic stem-cell disorders and mammalian size
Authors: Lopes Joao V. , Pacheco Jorge M. , Dingli David
Published: August 2007

Hematopoietic stem cells (HSCs) can both self renew and differentiate into precursors of all types of blood cells. HSCs are divided into an active pool and a quiescent reserve. Cells selected for the active pool contribute to hematopoiesis for many years. Mutations in HSCs can lead to neoplasms such as chronic myeloid leukemia, although the risk of neoplastic HSC disorders varies across mammals. We use allometric scaling relations combined with mutation-selection evolutionary dynamics to determine which mammalian species is most resistant to HSC disorders. We find that the advantage of large mammals at escaping the selective pressure of cancer cells is insufficient to overcome the increased risk of acquiring mutations. Hence, mutation dominates, which favors smaller stem-cell pools and, consequently, smaller mammals, since these minimize the development of mutations in the active stem-cell pool. Consequently, the smaller the active stem-cell pools, the better.
Modular co-evolution of metabolic networks
Authors: Zhao Jing , Ding Guo-Hui , Tao Lin , Yu Hong , Yu Zhong-Hao , Luo Jian-Hua , Cao Zhi-Wei , Li Yi-Xue
Published: August 2007

Background

The architecture of biological networks has been reported to exhibit high level of modularity, and to some extent, topological modules of networks overlap with known functional modules. However, how the modular topology of the molecular network affects the evolution of its member proteins remains unclear.

Results

In this work, the functional and evolutionary modularity of Homo sapiens (H. sapiens) metabolic network were investigated from a topological point of view. Network decomposition shows that the metabolic network is organized in a highly modular core-periphery way, in which the core modules are tightly linked together and perform basic metabolism functions, whereas the periphery modules only interact with few modules and accomplish relatively independent and specialized functions. Moreover, over half of the modules exhibit co-evolutionary feature and belong to specific evolutionary ages. Peripheral modules tend to evolve more cohesively and faster than core modules do.

Conclusion

The correlation between functional, evolutionary and topological modularity suggests that the evolutionary history and functional requirements of metabolic systems have been imprinted in the architecture of metabolic networks. Such systems level analysis could demonstrate how the evolution of genes may be placed in a genome-scale network context, giving a novel perspective on molecular evolution.
A comprehensive system for evaluation of remote sequence similarity detection
Authors: Qi Yuan , Sadreyev Ruslan I , Wang Yong , Kim Bong-Hyun , Grishin Nick V
Published: August 2007

Background

Accurate and sensitive performance evaluation is crucial for both effective development of better structure prediction methods based on sequence similarity, and for the comparative analysis of existing methods. Up to date, there has been no satisfactory comprehensive evaluation method that (i) is based on a large and statistically unbiased set of proteins with clearly defined relationships; and (ii) covers all performance aspects of sequence-based structure predictors, such as sensitivity and specificity, alignment accuracy and coverage, and structure template quality.

Results

With the aim of designing such a method, we (i) select a statistically balanced set of divergent protein domains from SCOP, and define similarity relationships for the majority of these domains by complementing the best of information available in SCOP with a rigorous SVM-based algorithm; and (ii) develop protocols for the assessment of similarity detection and alignment quality from several complementary perspectives. The evaluation of similarity detection is based on ROC-like curves and includes several complementary approaches to the definition of true/false positives. Reference-dependent approaches use the 'gold standard' of pre-defined domain relationships and structure-based alignments. Reference-independent approaches assess the quality of structural match predicted by the sequence alignment, with respect to the whole domain length (global mode) or to the aligned region only (local mode). Similarly, the evaluation of alignment quality includes several reference-dependent and -independent measures, in global and local modes. As an illustration, we use our benchmark to compare the performance of several methods for the detection of remote sequence similarities, and show that different aspects of evaluation reveal different properties of the evaluated methods, highlighting their advantages, weaknesses, and potential for further development.

Conclusion

The presented benchmark provides a new tool for a statistically unbiased assessment of methods for remote sequence similarity detection, from various complementary perspectives. This tool should be useful both for users choosing the best method for a given purpose, and for developers designing new, more powerful methods. The benchmark set, reference alignments, and evaluation codes can be downloaded from ftp://iole.swmed.edu/pub/evaluation/.
Exonization of the LTR transposable elements in human genome
Authors: Piriyapongsa Jittima , Polavarapu Nalini , Borodovsky Mark , McDonald John
Published: August 2007

Background

Retrotransposons have been shown to contribute to evolution of both structure and regulation of protein coding genes. It has been postulated that the primary mechanism by which retrotransposons contribute to structural gene evolution is through insertion into an intron or a gene flanking region, and subsequent incorporation into an exon.

Results

We found that Long Terminal Repeat (LTR) retrotransposons are associated with 1,057 human genes (5.8%). In 256 cases LTR retrotransposons were observed in protein-coding regions, while 50 distinct protein coding exons in 45 genes were comprised exclusively of LTR RetroTransposon Sequence (LRTS). We go on to reconstruct the evolutionary history of an alternatively spliced exon of the Interleukin 22 receptor, alpha 2 gene (IL22RA2) derived from a sequence of retrotransposon of the Mammalian apparent LTR retrotransposons (MaLR) family. Sequencing and analysis of the homologous regions of genomes of several primates indicate that the LTR retrotransposon was inserted into the IL22RA2 gene at least prior to the divergence of Apes and Old World monkeys from a common ancestor (~25 MYA). We hypothesize that the recruitment of the part of LTR as a novel exon in great ape species occurred prior to the divergence of orangutans and humans from a common ancestor (~14 MYA) as a result of a single mutation in the proto-splice site.

Conclusion

Our analysis of LRTS exonization events has shown that the patterns of LRTS distribution in human exons support the hypothesis that LRTS played a significant role in human gene evolution by providing cis-regulatory sequences; direct incorporation of LTR sequences into protein coding regions was observed less frequently. Combination of computational and experimental approaches used for tracing the history of the LTR exonization process of IL22RA2 gene presents a promising strategy that could facilitate further studies of transposon initiated gene evolution.
Dimerization of inositol monophosphatase Mycobacterium tuberculosis SuhB is not constitutive, but induced by binding of the activator Mg2+
Authors: Brown Alistair K , Meng Guoyu , Ghadbane Hemza , Scott David J , Dover Lynn G , Nigou Jérôme , Besra Gurdyal S , Fütterer Klaus
Published: August 2007

Background

The cell wall of Mycobacterium tuberculosis contains a wide range of phosphatidyl inositol-based glycolipids that play critical structural roles and, in part, govern pathogen-host interactions. Synthesis of phosphatidyl inositol is dependent on free myo-inositol, generated through dephosphorylation of myo-inositol-1-phosphate by inositol monophosphatase (IMPase). Human IMPase, the putative target of lithium therapy, has been studied extensively, but the function of four IMPase-like genes in M. tuberculosis is unclear.

Results

We determined the crystal structure, to 2.6 Å resolution, of the IMPase M. tuberculosis SuhB in the apo form, and analysed self-assembly by analytical ultracentrifugation. Contrary to the paradigm of constitutive dimerization of IMPases, SuhB is predominantly monomeric in the absence of the physiological activator Mg2+, in spite of a conserved fold and apparent dimerization in the crystal. However, Mg2+ concentrations that result in enzymatic activation of SuhB decisively promote dimerization, with the inhibitor Li+ amplifying the effect of Mg2+, but failing to induce dimerization on its own.

Conclusion

The correlation of Mg2+-driven enzymatic activity with dimerization suggests that catalytic activity is linked to the dimer form. Current models of lithium inhibition of IMPases posit that Li+ competes for one of three catalytic Mg2+ sites in the active site, stabilized by a mobile loop at the dimer interface. Our data suggest that Mg2+/Li+-induced ordering of this loop may promote dimerization by expanding the dimer interface of SuhB. The dynamic nature of the monomer-dimer equilibrium may also explain the extended concentration range over which Mg2+ maintains SuhB activity.
PROUD: Effects of preoperative long-term immunonutrition in patients listed for liver transplantation
Authors: Nickkholgh Arash , Schneider Heinz , Encke Jens , Büchler Markus W , Schmidt Jan , Schemmer Peter
Published: August 2007

Background

Patients with end stage liver disease are characteristically malnourished which is associated with poor outcome. Formulas enriched with arginine, ω-3 fatty acids, and nucleotides, "immunonutrients", potentially improve their nutritional status. This study is designed to evaluate the clinical outcome of long-term "immunonutrition" of patients with end-stage liver disease while on the waiting list for liver transplantation.

Methods/design

A randomized controlled double blind multi-center clinical trial with two parallel groups comprising a total of 142 newly registered patients for primary liver transplantation has been designed to assess the safety and efficacy of the long-term administration of ORAL IMPACT®, an "immunonutrient" formula, while waiting for a graft. Patients will be enrolled the day of registration on the waiting list for liver transplantation. Study ends on the day of transplantation. Primary endpoints include improved patients' nutritional and physiological status, as measured by mid-arm muscle area, triceps skin fold thickness, grip strength, and fatigue score, as well as patients' health related quality of life. Furthermore, patients will be followed for 12 postoperative weeks to evaluate anabolic recovery after transplantation as shown by reduced post-transplant mechanical ventilation, hospital stay, wound healing, infectious morbidities (pneumonia, intraabdominal abscess, sepsis, line sepsis, wound infection, and urinary tract infection), acute and chronic rejection, and mortality.

Discussion

Formulas enriched with arginine, ω-3 fatty acids, and nucleotides have been proven to be beneficial in reducing postoperative infectious complications and length of hospital stay among the patients undergoing elective gastrointestinal surgery. Possible mechanisms include downregulation of the inflammatory responses to surgery and immune modulation rather than a sole nutritional effect.

Trial registration

ClinicalTrials.gov NCT00495859
No supra-additive effects of goserelin and radiotherapy on clonogenic survival of prostate carcinoma cells in vitro
Authors: Hermann Robert M , Schwarten Dag , Fister Stefanie , Grundker Carsten , Rave-Frank Margret , Nitsche Mirko , Hille Andrea , Thelen Paul , Schmidberger Heinz , Christiansen Hans
Published: August 2007

Background

Oncological results of radiotherapy for locally advanced prostate cancer (PC) are significantly improved by simultaneous application of LHRH analoga (e.g. goserelin). As 85% of PC express LHRH receptors, we investigated the interaction of goserelin incubation with radiotherapy under androgen-deprived conditions in vitro.

Methods

LNCaP and PC-3 cells were stained for LHRH receptors. Downstream the LHRH receptor, changes in protein expression of c-fos, phosphorylated p38 and phosphorylated ERK1/2 were analyzed by means of Western blotting after incubation with goserelin and irradiation with 4 Gy. Both cell lines were incubated with different concentrations of goserelin in hormone-free medium. 12 h later cells were irradiated (0 – 4 Gy) and after 12 h goserelin was withdrawn. Endpoints were clonogenic survival and cell viability (12 h, 36 h and 60 h after irradiation).

Results

Both tested cell lines expressed LHRH-receptors. Changes in protein expression demonstrated the functional activity of goserelin in the tested cell lines. Neither in LNCaP nor in PC-3 any significant effects of additional goserelin incubation on clonogenic survival or cell viability for all tested concentrations in comparison to radiation alone were seen.

Conclusion

The clinically observed increase in tumor control after combination of goserelin with radiotherapy in PC cannot be attributed to an increase in radiosensitivity of PC cells by goserelin in vitro.
The temporal program of peripheral blood gene expression in the response of nonhuman primates to Ebola hemorrhagic fever
Authors: Rubins Kathleen H , Hensley Lisa E , Wahl-Jensen Victoria , Daddario DiCaprio Kathleen M , Young Howard A , Reed Douglas S , Jahrling Peter B , Brown Patrick O , Relman David A , Geisbert Thomas W
Published: August 2007

Background

Infection with Ebola virus (EBOV) causes a fulminant and often fatal hemorrhagic fever. In order to improve our understanding of EBOV pathogenesis and EBOV-host interactions, we examined the molecular features of EBOV infection in vivo.

Results

Using high-density cDNA microarrays, we analyzed genome-wide host expression patterns in sequential blood samples from nonhuman primates infected with EBOV. The temporal program of gene expression was strikingly similar between animals. Of particular interest were features of the data that reflect the interferon response, cytokine signaling, and apoptosis. Transcript levels for tumor necrosis factor-α converting enzyme (TACE)/α-disintegrin and metalloproteinase (ADAM)-17 increased during days 4 to 6 after infection. In addition, the serum concentration of cleaved Ebola glycoprotein (GP2 delta) was elevated in late-stage EBOV infected animals. Of note, we were able to detect changes in gene expression of more than 300 genes before symptoms appeared.

Conclusion

These results provide the first genome-wide ex vivo analysis of the host response to systemic filovirus infection and disease. These data may elucidate mechanisms of viral pathogenesis and host defense, and may suggest targets for diagnostic and therapeutic development.
Neutrophil transepithelial migration in response to the chemoattractant fMLP but not C5a is phospholipase D-dependent and related to the use of CD11b/CD18
Authors: Carrigan Svetlana O , Pink Desmond B S , Stadnyk Andrew W
Published: August 2007

In Crohn’s disease and ulcerative colitis patients, the numbers of neutrophils recovered from stool directly correlates with the severity of disease, implying that neutrophils in the lumen contribute to the tissue destruction; therefore, it is important to understand the mechanisms behind transintestinal epithelial migration. Neutrophil transintestinal epithelial migration to fMLP is appreciated to be CD11b/CD18 integrin (Mac-1)-dependent, while we recently reported that migration to C5a is Mac-1-independent. Here, we investigated whether phospholipase D (PLD), a signaling molecule linked to chemoattractant activation of neutrophils, is necessary for both Mac-1-dependent and Mac-1-independent migration. Both fMLP and C5a increased neutrophil expression of the Mac-1 activation epitope, indicating PLD was activated. This up-regulation was dose-dependently prevented by incubation of neutrophils in 1-butanol, an inhibitor of PLD activity. Despite this effect on Mac-1, 1-butanol did not prevent neutrophil migration across acellular filters. Incubation in 1-butanol did inhibit fMLP but not C5a-mediated migration across intestinal epithelial cell monolayers, showing that transepithelial migration to fMLP but not C5a is dependent on PLD. The addition of phosphatidic acid, a reaction product of PLD, partially restored fMLP-mediated transepithelial migration in the presence of 1-butanol but not the migration of Mac-1-deficient neutrophil-differentiated HL-60 cells. Thus PLD control over expression of the Mac-1 activation epitope is critical for neutrophil migration to fMLP but not C5a. Moreover, as PLD controls other neutrophil functions, such as the oxidative response, degranulation, and protease release, we could exclude these functions as being important in neutrophil transepithelial migration to C5a.
Single Nucleotide Polymorphisms in the NOD2/CARD15 Gene Are Associated With an Increased Risk of Relapse and Death for Patients With Acute Leukemia After Hematopoietic Stem-Cell Transplantation With Unrelated Donors
Authors: Mayor Neema P. , Shaw Bronwen E. , Hughes Derralynn A. , Maldonado-Torres Hazael , Madrigal J. Alejandro , Keshav Satish , Marsh Steven G.E.
Published: August 2007

Purpose

Hematopoietic stem cell transplantation (HSCT) is an important option in the management of acute leukemia, but the risk of disease relapse and death remains appreciable. Recent studies have suggested that nucleotide-binding oligomerization domain 2 (NOD2)/caspase recruitment domain 15 (CARD15) gene single nucleotide polymorphisms (SNPs), implicated in innate immunity and Crohn's disease, may also affect immune function post-HSCT.

Patients and Methods

NOD2/CARD15 genotypes were analyzed in 196 patients diagnosed with acute leukemia and their unrelated donors. The pairs are part of a previously well-characterized cohort with a median follow-up of 2.2 years (range, 0.42 to 6.61 years). T-cell depletion was used in 83% of pairs.

Results

NOD2/CARD15 SNPs were associated with a reduction in overall survival (44% v 22%; log-rank P = .0087) due to an increase in disease relapse (32% v 54%; Gray's test P = .001) as compared with wild-type pairs. In multivariate analyses, the two most significant factors impacting outcome were transplantation in relapse and the presence of SNPs. The incidence of acute graft-versus-host disease was low and there was no significant difference due to the presence of SNPs.

Conclusion

These data indicate an unrecognized role for the NOD2/CARD15 gene in unrelated donor HSCT for acute leukemia. The increased risk of disease relapse suggests that the wild-type gene product may contribute to a graft-versus-leukemia effect. These data suggest that NOD2/CARD15 genotyping before transplantation may contribute to prognosis and influence clinical management.
Electro-rheological polymers
Authors: Akhavan J
Published: August 2007

Smart fluids in the form of electro-rheological (ER) fluids are among the most spectacular of the smart materials. ER fluids are typically suspensions of semiconducting, solid particles dispersed in an insulating carrier liquid, which show a dramatic increase in flow resistance when an external electric field is applied. This reversible and rapid change in flow properties has potential applications in many electronically controlled mechanical devices. This article gives a short overview of the field of ER materials and their basic properties. Current and future developments with particular attention to electrorheological polymers have been reviewed.
Auxetic materials
Authors: Alderson A , Alderson K L
Published: August 2007

The current status of research into auxetic (negative Poisson's ratio) materials is reviewed, with particular focus on those aspects of relevance to aerospace engineering. Developments in the modelling, design, manufacturing, testing, and potential applications of auxetic cellular solids, polymers, composites, and sensor/actuator devices are presented. Auxetic cellular solids in the forms of honeycombs and foams are reviewed in terms of their potential in a diverse range of applications, including as core materials in curved sandwich panel composite components, radome applications, directional pass band filters, adaptive and deployable structures, MEMS devices, filters and sieves, seat cushion material, energy absorption components, viscoelastic damping materials, and fastening devices. The review of auxetic polymers includes the fabrication and characterization of microporous polymer solid rods, fibres, and films, as well as progress towards the first synthetic molecular-level auxetic polymer. Potential auxetic polymer applications include self-locking reinforcing fibres in composites, controlled release media, and self-healing films. Auxetic composite laminates and composites containing auxetic constituents are reviewed and enhancements in fracture toughness, and static and low velocity impact performance are presented to demonstrate potential in energy absorber components. Finally, the potential of auxetics as strain amplifiers, piezoelectric devices, and structural health monitoring components is presented.
Aerospace applications of shape memory alloys
Authors: Hartl D J , Lagoudas D C
Published: August 2007

With the increased emphasis on both reliability and multi-functionality in the aerospace industry, active materials are fast becoming an enabling technology capturing the attention of an increasing number of engineers and scientists worldwide. This article reviews the class of active materials known as shape memory alloys (SMAs), especially as used in aerospace applications. To begin, a general overview of SMAs is provided. Their useful properties and engineering effects are described and the methods in which these may be utilized are discussed. A review of past and present aerospace applications is presented. The discussion addresses applications for both atmospheric earth flight as well as space flight. To complete the discussion, SMA design challenges and methodologies are addressed and the future of the field is examined.
Engineering nanostructures at surfaces using nanolithography
Authors: Diegoli S , Hamlett C A E , Leigh S J , Mendes P M , Preece J A
Published: August 2007

In just a few years, exploring nanostructured materials has become a new theme common to many disciplines of science and engineering. Recent surge of interest in these nanostructured systems stems from the remarkable effects that may arise from the critical size reduction. Structured materials on the nanometre scale can lead to improved and sometimes novel properties with emerging applications ranging from novel highly functional devices to advanced chemical and biological sensors. Significant advances made in nanomaterials research, together with improved lithographic fabrication strategies have led to dramatic enhancements in the creation of complex and well-defined nanostructures on surfaces. This article reviews the status of research and development in nanostructured materials, with particular focus on the recent advances on nanolithographic techniques. Finally, perspectives and future challenges in this emerging field of research are also discussed.
Dynamic Bid Prices in Revenue Management
Authors: Adelman Daniel
Published: August 2007

We formally derive the standard deterministic linear program (LP) for bid-price control by making an affine functional approximation to the optimal dynamic programming value function. This affine functional approximation gives rise to a new LP that yields tighter bounds than the standard LP. Whereas the standard LP computes static bid prices, our LP computes a time trajectory of bid prices. We show that there exist dynamic bid prices, optimal for the LP, that are individually monotone with respect to time. We provide a column generation procedure for solving the LP within a desired optimality tolerance, and present numerical results on computational and economic performance.
Optimal Control of Serial Inventory Systems with Fixed Replenishment Intervals
Authors: van Houtum Geert-Jan , Scheller-Wolf Alan , Yi Jinxin
Published: August 2007

We consider a single-item, periodic-review, serial inventory/production system, with linear inventory-holding and penalty costs. To facilitate shipment consolidation and capacity planning, we assume that the system has implemented fixed replenishment intervals; each stage is allowed to order only at given equidistant times. Further, for each stage except the most downstream one, the replenishment interval is assumed to be an integer multiple of the replenishment interval of the next downstream stage. This reflects the fact that the further upstream in a supply chain, the higher setup times and costs tend to be, and thus larger batches are desired. Our model with fixed replenishment intervals is a direct generalization of the serial model of Clark and Scarf (1960). For this generalized model, we prove the optimality of base-stock policies, we derive newsboy equations for the optimal base-stock levels, and we describe an efficient exact solution procedure for the case with mixed Erlang demands. Finally, we present extensions to assembly systems and to systems with a modified fill-rate constraint instead of backorder costs.
A Screening Technique for Joint Chance-Constrained Programming for Air-Quality Management
Authors: An Hyunhee , Eheart J. Wayland
Published: August 2007

This technical note presents a screening technique for using chance-constrained programming to achieve overall system (i.e., joint) reliability when there is statistical dependence between constraints representing an ambient air-quality requirement at different geographical locations. The technique is intended to determine whether the full analysis of row interdependence, which requires more intensive programming and larger computational effort, is warranted, by examining a possible spectrum of solutions at three extreme cases of row dependence. The technique is illustrated for airborne particulate emissions control, in which the overall cost of controlling particulate emissions from two electrostatic precipitators is minimized in a manner that maintains ground-level particulate concentration at all receptors with a prescribed reliability.

In accordance with the theory presented here, such screening is achieved by setting the required reliability values of individual constraints according to assumptions of complete codependence, zero codependence, and complete negative codependence. In application, these reliability values represent the probability of achieving the ambient concentration standard at several receptor locations. The results of the screening technique are compared to those of two more computationally intensive methods for achieving overall system reliability. It is found that, for a given example, the screening technique brackets the results of those full-analysis methods for row dependence, as expected.
Locating a Circle on a Sphere
Authors: Brimberg Jack , Juel Henrik , Schöbel Anita
Published: August 2007

We consider the problem of locating a spherical circle with respect to existing facilities on a sphere, such that the sum of distances between the circle and the facilities is minimized or such that the maximum distance is minimized. The problem properties are analyzed, and we give solution procedures. When the circle to be located is restricted to be a great circle, some simplifications are possible. The models may be used in preliminary studies on the location of large linear facilities on the earth’s surface, such as superhighways, pipelines, and transmission lines, or in totally different contexts such as search-and-rescue missions and medical or biological studies.
Incentives and Commonality in a Decentralized Multiproduct Assembly System
Authors: Bernstein Fernando , DeCroix Gregory A. , Wang Yulan
Published: August 2007

In this paper, we explore the impact of decentralized decision making on the behavior of multiproduct assembly systems. Specifically, we consider a system where three components (two product specific and one common) are used to produce two end products to satisfy stochastic customer demands. We study the system under both centralized and decentralized decision making. In the decentralized system, we prove that for any set of wholesale prices, there exists a unique Pareto-optimal equilibrium in the suppliers’ capacity game. We show that the assembler’s optimal wholesale prices lie in one of two regions—one leads to capacity imbalance and one does not. We use these results to derive insights regarding the inefficiencies that decentralization can cause in such systems. In particular, several of our findings indicate that outsourcing the management of component supplies may inhibit the use of operational hedging approaches for managing uncertainty.
Integrated Production-Inventory-Distribution System Design with Risk Pooling: Model Formulation and Heuristic Solution
Authors: Vidyarthi Navneet , Çelebi Emre , Elhedhli Samir , Jewkes Elizabeth
Published: August 2007

In this paper, we consider a multiproduct two-echelon production-inventory-distribution system design model that captures risk-pooling effects by consolidating the safety-stock inventory of the retailers at distribution centers (DCs). We propose a model that determines plant and DC locations, shipment levels from plants to the DCs, safety-stock levels at DCs, and the assignment of retailers to DCs by minimizing the sum of fixed facility location costs, transportation costs, and safety-stock costs. The model is formulated as a nonlinear mixed-integer programming problem and linearized using piecewise-linear functions. The formulation is strengthened using redundant constraints. Lagrangean relaxation is applied to decompose the problem by echelon. A lower bound is provided by the Lagrangean relaxation, while a heuristic is proposed that uses the solution of the subproblems to construct an overall feasible solution. Computational results reveal that the Lagrangean relaxation provides a sharp lower bound and a heuristic solution that is within 5% of the optimal solution.
The Robust Traveling Salesman Problem with Interval Data
Authors: Montemanni R. , Barta J. , Mastrolilli M. , Gambardella L. M.
Published: August 2007

The traveling salesman problem is one of the most famous combinatorial optimization problems and has been intensively studied. Many extensions to the basic problem have also been proposed, with the aim of making the resulting mathematical models as realistic as possible. We present a new extension to the basic problem, where travel times are specified as a range of possible values. This model reflects the intrinsic difficulties of estimating travel times in reality. We apply the robust deviation criterion to drive optimization over the interval data problem so obtained. Some interesting theoretical properties of the new optimization problems are identified and discussed, together with a new mathematical formulation and some exact and heuristic algorithms. Computational experiments are finally presented.
Waiting Strategies for Anticipating Service Requests from Known Customer Locations
Authors: Thomas Barrett W.
Published: August 2007

This paper considers a dynamic and stochastic routing problem in which information about customer locations and probabilistic information about future service requests are used to maximize the expected number of customers served by a single uncapacitated vehicle. The problem is modeled as a Markov decision process, and analytical results on the structure of the optimal policy are derived. For the case of a single dynamic customer, we completely characterize the optimal policy. Using the analytical results, we propose a real-time heuristic and demonstrate its effectiveness compared with a series of other intuitively appealing heuristics. We also use computational tests to determine the heuristic value of knowing both customer locations and probabilistic information about future service requests.
A Branch-and-Cut Algorithm for a Vendor-Managed Inventory-Routing Problem
Authors: Archetti Claudia , Bertazzi Luca , Laporte Gilbert , Speranza Maria Grazia
Published: August 2007

We consider a distribution problem in which a product has to be shipped from a supplier to several retailers over a given time horizon. Each retailer defines a maximum inventory level. The supplier monitors the inventory of each retailer and determines its replenishment policy, guaranteeing that no stockout occurs at the retailer (vendor-managed inventory policy). Every time a retailer is visited, the quantity delivered by the supplier is such that the maximum inventory level is reached (deterministic order-up-to level policy). Shipments from the supplier to the retailers are performed by a vehicle of given capacity. The problem is to determine for each discrete time instant the quantity to ship to each retailer and the vehicle route. We present a mixed-integer linear programming model and derive new additional valid inequalities used to strengthen the linear relaxation of the model. We implement a branch-and-cut algorithm to solve the model optimally. We then compare the optimal solution of the problem with the optimal solution of two problems obtained by relaxing in different ways the deterministic order-up-to level policy. Computational results are presented on a set of randomly generated problem instances.
Convergence to Equilibrium in Dynamic Traffic Networks when Route Cost Is Decay Monotone
Authors: Mounce Richard
Published: August 2007

This paper addresses the issue of convergence to equilibrium in dynamic traffic assignment. Within-day time is considered to be a continuous variable, so that traffic flows and costs are functions of within-day time. Flow propagates along routes connecting origin-destination (OD) pairs with the demand for travel between each OD pair considered to be rigid (fixed from day to day although it can vary within day). Day-to-day time is also modelled as continuous with the day-to-day dynamical system derived naturally from the usual dynamical user equilibrium (DUE) condition. This paper focuses on the bottleneck model, which has deterministic vertical queueing at bottleneck link exits when flow exceeds capacity. A new property called decay monotonicity is introduced. The link delay (and hence link cost) function is shown to be a decay monotone function of link flow provided that the link capacity is continuously differentiable and positive. In a restricted version of the single bottleneck per route case, it is shown that link cost decay monotonicity implies route cost decay monotonicity. Decay monotonicity of the route cost function is shown to be sufficient for convergence to equilibrium of the dynamical system.
The Rookwood Driving Battery: Normative older adult performance
Authors: Rees Janice. , McKenna Pat. , Bell Vaughan. , Skucek Emily. , Nichols E. , Fisher P.
Published: August 2007

Objectives

The current study aimed to obtain older adult normative data on a neuropsychological battery in relation to functions underlying driving ability. The effect of age on performance on the battery was previously unknown; normative data revision was necessary to enable more appropriate use of the battery with older clients.

Design

Cross‐sectional cohort study.

Methods

Volunteers were sought from healthy older people living independently in the community to complete the Rookwood Driving Battery. A group of 202 volunteers above the age of 70 were recruited from local social groups to complete the battery. Of these, 184 completed a screening test of cognitive integrity (Mini Mental State Examination, MMSE). The age ranged from 70 to 96 (mean age=81 years,SD= 5.438). In the total sample, 155 (77%) were females.

Results

Results of the MMSE indicated that 161 (87.5%) of the group fell above a cut‐off (25/30) typically used in epidemiological studies to identify age‐related cognitive decline. Of these cognitively intact volunteers, performance was marked by higher battery error scores (mean=5.12,SD= 3.75) than those observed in an earlier normative study using younger volunteers below 70 years of age (mean=1.41,SD= 1.87). The two age groups differed significantly on all 10 battery subtests; in all cases the level of significance was .002 or less; for nine subtests, significance fell below .001. In the ‘intact’ older group, battery performance was observed to be closely related to score on the MMSE, a test of general cognitive integrity (r= .558,p= .01).

Conclusions

Performance on the Rookwood Battery differs for the over 70s and under 70s. The authors suggest essential modifications in its use with older people.
Can children construct inverse relations in arithmetic? Evidence for individual differences in the development of conceptual understanding and computational skill
Authors: Gilmore Camilla K. , Bryant Peter
Published: August 2007

Understanding conceptual relationships is an important aspect of learning arithmetic. Most studies of arithmetic, however, do not distinguish between children's understanding of a concept and their ability to identify situations in which it might be relevant. We compared 8‐ to 9‐year‐old children's use of a computational shortcut based on the inverse relationship between addition and subtraction, in problems where it was transparently applicable (e.g. 17+11−11=□) and where it was not (e.g. 15+11−8−3=□). Most children were able to construct inverse transformations and apply the shortcut in at least some situations, although they used the shortcut more for problems where it was transparently applicable. There were individual differences in the relationship between children's understanding of the inverse relationship and computational skill that have implications for theories of mathematical development.
Low Dietary Riboflavin but Not Folate Predicts Increased Fracture Risk in Postmenopausal Women Homozygous for the MTHFR 677 T Allele
Authors: Yazdanpanah Nahid , Uitterlinden André G , Zillikens M Carola , Jhamai Mila , Rivadeneira Fernando , Hofman Albert , de Jonge Robert , Lindemans Jan , Pols Huibert AP , van Meurs Joyce B
Published: August 2007

The MTHFR C677T polymorphism is associated with mildly elevated homocysteine levels when folate and/or riboflavin status is low. Furthermore, a mildly elevated homocysteine level is a risk factor for osteoporotic fractures. We studied whether dietary intake of riboflavin and folate modifies the effects of the MTHFR C677T variant on fracture risk in 5035 men and women from the Rotterdam Study. We found that the MTHFR C677T variant interacts with dietary riboflavin intake to influence fracture risk in women.

Introduction: The MTHFR C677T polymorphism is associated with mildly elevated homocysteine (Hcy) levels in the presence of low folate and/or riboflavin status. A mildly elevated Hcy level was recently identified as a modifiable risk factor for osteoporotic fracture. We studied whether dietary intake of riboflavin and folate modifies the effects of the MTHFR C677T polymorphism on BMD and fracture risk.

Materials and Methods: We studied 5035 individuals from the Rotterdam Study, ≥55 yr of age, who had data available on MTHFR, nutrient intake, and fracture risk. We performed analysis on Hcy levels in a total of 666 individuals, whereas BMD data were present for 4646 individuals (2692women).

Results: In the total population, neither the MTHFR C677T polymorphism nor low riboflavin intake was associated with fracture risk and BMD. However, in the lowest quartile of riboflavin intake, female 677-T homozygotes had a 1.8 (95% CI: 1.1-2.9, p = 0.01) times higher risk for incident osteoporotic fractures and a 2.6 (95% CI: 1.3-5.1, p = 0.01) times higher risk for fragility fractures compared with the 677-CC genotype (interaction, p = 0.0002). This effect was not seen for baseline BMD in both men and women. No significant influence was found for dietary folate intake on the association between the MTHFR C677T genotype and fracture risk or BMD. In the lowest quartile of dietary riboflavin intake, T-homozygous individuals (men and women combined) had higher (22.5%) Hcy levels compared with C-homozygotes (mean difference = 3.44 νM, p = 0. 01; trend, p = 0.02).

Conclusions: In this cohort of elderly whites, the MTHFR C677T variant interacts with dietary riboflavin intake to influence fracture risk in women.
Development of American National Standards for Sustainable Building Products
Authors: Wilson Jane M. , Bowen Jaclyn M.
Published: August 2007

Numerous interior furnishing products have been introduced into the market claiming a variety of environmental attributes. End users are requesting access to information other than marketing claims to help understand the environmental benefits of each product and to be able to compare products using a consistent basis of measurement. Developing responses to these requests is time-consuming and expensive for manufacturers. Having a consensus set of attributes that define and identify sustainable products in the form of American National Standards will assist both manufacturers and end users in communicating environmental and sustainability related product benefits. NSF International, an ANSI-accredited standards development organization, is working with stakeholders in the contract textile, carpet and rug, and resilient flooring sectors to initiate separate sustainability standardization efforts for these product categories. By working with multiple industries that affect the indoor environment, NSF intends to promote the sharing of best sustainability practices across standards committees, so that the standards are developed in a consistent and cohesive manner. Establishment of these standards will serve to directly support and inform the end user decision-making process for the evaluation of products in these categories with respect to identifying the desired sustainability performance for products to be utilized within specific indoor environments.