bluuebunny/crossref_metadata_2025 huggingface dataset:
Endogenous secretory receptor for advanced glycation endproducts as a novel prognostic marker in chondrosarcoma
Authors: Takeuchi Akihiko , Yamamoto Yasuhiko , Tsuneyama Koichi , Cheng Chunmei , Yonekura Hideto , Watanabe Takuo , Shimizu Katsuji , Tomita Katsuro , Yamamoto Hiroshi , Tsuchiya Hiroyuki
Published: May 2007

BACKGROUND

Chondrosarcoma, the second most frequent primary malignant bone tumor, is classified into 3 grades according to histologic criteria of malignancy. However, a low‐grade lesion can be difficult to distinguish from a benign enchondroma, whereas some histologically low‐grade lesions may carry a poor prognosis. The receptor for advanced glycation endproducts (RAGE) and its ligand, high‐mobility group box‐1 (HMGB1), was quantified in enchondromas and chondrosarcomas to determine whether these markers were associated with histological malignancy and prognosis.

METHODS

Enchondromas (n = 20) and typical chondrosarcomas (n = 39) were evaluated for RAGE, endogenous secretory RAGE (esRAGE, a splice variant form), and HMGB1 protein expression by immunohistochemistry including laser confocal microscopy. The content of esRAGE in resected specimens was measured with an enzyme‐linked immunosorbent assay. Associations of these molecules with histology and clinical behavior of tumors were analyzed.

RESULTS

Expression of esRAGE and HMGB1 was observed in all specimens. The numbers of cells positive for esRAGE and HMGB1 expression were positively associated with histologic grade. Expression of esRAGE was significantly higher in chondrosarcomas than in enchondromas (P < .001). Tissue esRAGE content was also significantly higher in grade 1 and 2 chondrosarcomas than enchondromas (P = .0255 and P = .008, respectively). High expression of esRAGE in grade 1 chondrosarcoma was associated with subsequent recurrence (P = .0013), lung metastasis (P = .0071), and poor survival (P < .001).

CONCLUSIONS

Assessment of esRAGE expression should aid in diagnostic andprognostic determinations in chondrosarcoma. Cancer 2007. © 2007 American Cancer Society.
Molecular Distortion Effect on ff‐Emission in a Pr(III) Complex with 4,7‐Diphenyl‐1,10‐Phenanthroline
Authors: Ishii Ayumi , Kishi Shinobu , Ohtsu Hideki , Iimori Toshifumi , Nakabayashi Takakazu , Ohta Nobuhiro , Tamai Naoto , Melnik Milan , Hasegawa Miki , Shigesato Yuzo
Published: May 2007

The electronic and structural behaviour of a Pr(III) complex with 4,7‐diphenyl‐1,10‐phenanthroline, [Pr(bathophen)2(NO3)3], is investigated with respect to the effect of configuration changes on the Pr(III) centre. [Pr(bathophen)2(NO3)3] luminesces from the excited states of the ligand and the metal ion. The fluorescence, ff‐emission (1D2→3H4), and phosphorescence bands appear at 394, 608.2 and 482 nm, respectively, in the solid state. In acetonitrile, the complex also shows multiple emissions. From the time‐resolved emission and the lifetime measurements, the excitation energy‐transfer in [Pr(bathophen)2(NO3)3] is clarified, that is, the upper excited triplet level of the ligand acts as an energy donor, while the 1D2 levels of Pr(III) is the acceptor. Additionally, the emission phenomena of the complex can be modified by molecular distortion, particularly by rotation of the phenyl groups in the ligand.
Atomic Layer Deposition of BaTiO3 Thin Films—Effect of Barium Hydroxide Formation
Authors: Vehkamäki M. , Hatanpää T. , Ritala M. , Leskelä M. , Väyrynen S. , Rauhala E.
Published: May 2007

Barium titanate thin films are grown by atomic layer deposition (ALD) at 340 °C from barium cyclopentienyl and titanium methoxide precursors. H2O is used as the oxygen source. Binary reactions of Ba(tBu3C5H2)2 and H2O are first studied separately in BaO deposition and are found to result in a hydration/dehydration cycle, which is strongly influenced by the process temperature. Self‐limiting growth of amorphous barium titanate films becomes possible when Ti(OMe)4 – H2O growth cycles are mixed as well as possible with Ba(tBu3C5H2)2 – H2O cycles. The as‐deposited amorphous films are crystallized by post‐deposition annealing at 600 °C. Permittivities of 15 and 70 are measured for as‐deposited and post‐deposition annealed films, respectively. A charge density of 1.9 μC cm–2 (equivalent oxide thickness of 1.8 nm) and leakage current density ≤ 1 × 10–7 A cm–2 were achieved at 1 V bias with a 32 nm thick Ba–Ti–O film in a Pt electrode stack annealed at 600 °C.
Pulmonary metastasis of giant cell tumor of the bone diagnosed by fine‐needle aspiration biopsy
Authors: Cai Guoping , Ramdall Risha , Garcia Roberto , Levine Pascale
Published: May 2007

Giant cell tumor is a benign but locally aggressive tumor that primarily affects the epiphyses of long bones of young adults. Pulmonary metastases in giant cell tumor are rare (about 1–9%). Here, we report a case of metastatic pulmonary giant cell tumor in a patient who had a previous history of giant cell tumor of the distal femur with multiple recurrences. The diagnosis of pulmonary metastasis was achieved by cytologic evaluation with concurrent immunohistochemical studies in material obtained by fine‐needle aspiration biopsy. The aspirate smears contained clustered and dispersed mononuclear and osteoclast‐like giant cells that had bland nuclei with inconspicuous nucleoli. All multinucleated cells showed immunoreactivity to KP‐1 antibody, a histiocytic marker (not lineage specific) and only a subset of mononuclear cells (30%) stained with this marker. Twenty percent of the mononuclear cells also displayed increased Ki‐67 and p53 protein expression. The pulmonary metastasis was similar morphologically and immunophenotypically to the recurrent giant cell tumor of the bone. Diagn. Cytopathol. 2007;35:358–362. © 2007 Wiley‐Liss, Inc.
Developmental characteristics of AMPA receptors in chick lumbar motoneurons
Authors: Ni Xianglian , Sullivan Grace J. , Martin‐Caraballo Miguel
Published: May 2007

Ca2+ fluxes through ionotropic glutamate receptors regulate a variety of developmental processes, including neurite outgrowth and naturally occurring cell death. In the CNS, NMDA receptors were originally thought to be the sole source of Ca2+ influx through glutamate receptors; however, AMPA receptors also allow a significant influx of Ca2+ ions. The Ca2+ permeability of AMPA receptors is regulated by the insertion of one or more edited GluR2 subunits. In this study, we tested the possibility that changes in GluR2 expression regulate the Ca2+ permeability of AMPA receptors during a critical period of neuronal development in chick lumbar motoneurons. GluR2 expression is absent between embryonic day (E) 5 and E7, but increases significantly by E8 in the chick ventral spinal cord. Increased GluR2 protein expression is correlated with parallel changes in GluR2 mRNA in the motoneuron pool. Electrophysiological recordings of kainate‐evoked currents indicate a significant reduction in the Ca2+‐permeability of AMPA receptors between E6 and E11. Kainate‐evoked currents were sensitive to the AMPA receptor blocker GYKI 52466. Application of AMPA or kainate generates a significant increase in the intracellular Ca2+ concentration in E6 spinal motoneurons, but generates a small response in older neurons. Changes in the Ca2+‐permeability of AMPA receptors are not mediated by age‐dependent changes in the editing pattern of GluR2 subunits. These findings raise the possibility that Ca2+ influx through Ca2+‐permeable AMPA receptors plays an important role during early embryonic development in chick spinal motoneurons. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007
Health service utilization for eating disorders: Findings from a community‐based study
Authors: Mond Jonathan M. , Hay Phillipa J. , Rodgers Bryan , Owen Cathy
Published: May 2007

Background:

Prior use of health services was examined in a community sample of women with bulimic‐type eating disorders.

Method:

Participants (n = 159) completed a structured interview for the assessment of eating disorder psychopathology as well as questions concerning treatment‐seeking and type of treatment received.

Results:

Whereas a minority (40.3%) of participants had received treatment for an eating problem, most had received treatment for a general mental health problem (74.2%) and/or weight loss (72.8%), and all had used one or more self‐help treatments. Where treatment was received for an eating or general mental health problem, this was from a primary care practitioner in the vast majority of cases. Only half of those participants who reported marked impairment associated with an eating problem had ever received treatment for such a problem and less than one in five had received such treatment from a mental health professional.

Conclusion:

Women with bulimic‐type eating disorders rarely receive treatment for an eating problem, but frequently receive treatment for a general mental health problem and/or for weight loss. The findings underscore the importance of programs designed to improve the detection and management of eating disorders in primary care. © 2007 by Wiley Periodicals, Inc. Int J Eat Disord 2007
The use of guidelines for dissemination of “best practice” in primary care of patients with eating disorders
Authors: Currin Laura , Waller Glenn , Treasure Janet , Nodder Jane , Stone Christine , Yeomans Maria , Schmidt Ulrike
Published: May 2007

Objective:

A number of sets of clinical guidelines have been developed for the treatment of eating‐disordered patients. This study aimed to measure adherence to such guidance among family physicians working in primary care settings.

Method:

In the wake of the publication of national guidelines for “best practice,” family physicians in a large but diverse geographical region of the UK (population of 6.4 million) were approached and asked to complete a two‐stage survey.

Results:

Only 4% of these clinicians report using published guidelines or protocols, and none used the national guidelines that were available. Nor were these clinicians using the spirit of the guidelines, as there was little correspondence between recommended and actual treatment behavior.

Conclusion:

These findings suggest that specialist eating disorders services should not rely on guidelines to ensure the dissemination of best practice for these patients in primary care. Alternative means of dissemination are needed, and suggestions are made. © 2007 by Wiley Periodicals, Inc. Int J Eat Disord 2007
Differential role of IL‐2R signaling for CD8+ T cell responses in acute and chronic viral infections
Authors: Bachmann Martin F. , Wolint Petra , Walton Senta , Schwarz Katrin , Oxenius Annette
Published: May 2007

IL‐2 is a cytokine with multiple and even divergent functions; it has been described as a key cytokine for in vitro T cell proliferation but is also essential for down‐regulating T cell responses by inducing activation‐induced cell death as well as regulatory T cells. The in vivo analysis of IL‐2 function in regulating specific T cell responses has been hampered by the fact that mice deficient in IL‐2 or its receptors develop lymphoproliferative diseases and/or autoimmunity. Here we generated chimeric mice harboring both IL‐2R‐competent and IL‐2R‐deficient T cells and assessed CD8+ T cell induction, function and maintenance after acute or persistent viral infections. Induction and maintenance of CD8+ T cells were relatively independent of IL‐2R signaling during acute/resolved viral infection. In marked contrast, IL‐2 was crucial for secondary expansion of memory CD8+ T cells and for the maintenance of virus‐specific CD8+ T cells during persistent viral infections. Thus, depending on the chronicity of antigen exposure, IL‐2R signaling is either essential or largely dispensable for induction and maintenance of virus‐specific CD8+ T cell responses.
US health services employment: A time series analysis
Authors: Kendix Michael , Getzen Thomas E.
Published: May 2007

The growth of health services employment in the United States is modelled using ARIMA analysis, and related to the growth in total U.S. employment. It is argued that specific features of the medical care sector (licensed professional manpower, non‐profit firms, third‐party financing) create institutional rigidities which delay adjustment to macroeconomic conditions and other shocks. Tests of Granger causality and the pattern of coefficients in the cross‐correlation function show that health services employment does lag other sectors of the economy by an average of 2 to 4 years. A Box‐Jenkins transfer‐noise function model between total and health employment is constructed and evaluated, and the impact dynamics of adjustment to Medicare and Medicaid are estimated.
Inpatient and outpatient health care demand in Cairo, Egypt
Authors: Ellis Randall P. , McInnes D. Keith , Stephenson Elizabeth H.
Published: May 2007

This paper uses the results of a household survey conducted in Cairo, Egypt in 1992 to examine the factors that influence the demand for inpatient and outpatient health services. Multi‐stage discrete choice models of the demand for health care, which identify the importance of individual, household, and facility level variables on each treatment decision, are estimated separately for outpatients and inpatients. Consumers are assumed to decide whether to seek any treatment and then choose between three categories of providers: a large public hospital (Embaba Hospital), all other public providers, and private/charitable providers. The results confirm that more affluent consumers prefer the higher cost, higher quality private and charitable hospitals. Age, sex, education, and insurance are also found to strongly impact the use of medical services. The results are suggestive but do not conclusively show that inpatient care is less price responsive than outpatient care. Price responsiveness of inpatient and outpatient demand are imprecisely estimated because price is highly correlated with quality, and the available data on facility quality do not permit us to adequately control for quality variations across facilities.
Statistical analysis of cost outcomes in a randomized controlled clinical trial
Authors: Rutten‐van Mölken Maureen P. M. H. , Van Eddy K. A. , van Vliet René C. J. A.
Published: May 2007

This paper suggests an approach to deal with an estimation problem which is often encountered in analyzing the longitudinal cost data gathered in a clinical trial. The source of that estimation problem is twofold: 1) a considerable number of missing data due to treatment‐related withdrawal of severely affected patients with high health care costs in only one the treatment groups and 2) a heavily skewed cost distribution due to rare high‐cost events. The approach is illustrated using data from a trial comparing 3 different drug regimes.

In order to calculate costs per patient‐year in case of selectively missing data we extrapolated the costs of patients with incomplete follow‐up. Due to the skewness and the associated large variance in costs per patient‐year, these costs cannot be analyzed using common parametric statistical methods relying on underlying normal distributions. A logarithmic transformation was performed to approximate a normal distribution, reduce the impact of extreme values and create similar size variances in the treatment groups. An ordinary least squares regression analysis of transformed data then standardized for differences in patient characteristics between the groups. For the retransformation, the so‐called smearing estimate was used. This ‘transformation‐standardization‐retransformation’ approach enabled us to provide more consistent and efficient estimates of cost differences that were shown to be statistically significant and judged to be important.
The demand for cigarettes in california and behavioural risk factors
Authors: Hu Teh‐Wei , Ren Qui‐Fang , Keeler Theodore E. , Bartlett Joan
Published: May 2007

This study contributes to the understanding of the demand for cigarettes by taking into account the interdependence of smoking and other behavioural risk factors. Information on smoking and other behavioural risk factors including drinking, alcohol use, and obesity were obtained from the California Behavioural Risk Factor Survey for the period 1985–91. A monthly cigarette price index for California was constructed based on data obtained from the Bureau of Labor Statistics. A two‐part model was used to examine separately the effect of price on the decision to be a smoker, and on the amount of cigarettes smoked by smokers. The overall price elasticity of cigarettes was estimated at −0.46, with a price elasticity of −0.33 for smoking participation and of −0.22 for the amount of cigarettes consumed by smokers. The inclusion of other behavioural risk factors reduced the estimated price elasticity for smoking participation substantially, but had no effect on the conditional price elasticity for the quantity of cigarettes smoked.
On approximations in treatment costing
Authors: Whynes David K. , Walker Andrew R.
Published: May 2007

As detailed costing may be a time‐consuming and expensive exercise within an evaluation, economists will be conscious of the possibilities of taking short‐cuts. To explore the viability of such approaches in the context of acute care (the surgical treatment for colorectal cancer), we compare the results of a detailed costing study with reduced list costing and econometric estimation. We conclude, first, that use of a reduced list is likely to generate substantial research economies only at the expense of inaccuracy. Second, crude costing, based upon average costs of the specialty, is acceptable when the frame of reference is the aggregate. Such crude costing, however, is vulnerable to bias when specific sub‐samples of patients are to be considered. Finally, total costs are predictable from a restricted list of cost and event variables, and with a high degree of accuracy, although ex ante specification of the functional form is problematic.
The impact of nursing grade on the quality and outcome of nursing care
Authors: Carr‐Hill Roy A. , Dixon Paul , Griffiths Mary , Higgins Moira , McCaughan Dorothy , Rice Nigel , Wright Ken
Published: May 2007

The large industry which has grown up around the estimation of nursing requirements for a ward or for a hospital takes little account of variations in nursing skill; meanwhile nursing researchers tend to concentrate on the appropriate organisation of the nursing process to deliver best quality care. This paper, drawing on a Department of Health funded study, analyses the relation between skill mix of a group of nurses and the quality of care provided.

Detailed data was collected on 15 wards at 7 sites on both the quality and outcome of care delivered by nurses of different grades, which allowed for analysis at several levels from a specific nurse‐patient interaction to the shift sessions. The analysis shows a strong grade effect at the lowest level which is 'diluted' at each succeeding level of aggregation; there is also a strong ward effect at each of the lower levels of aggregation. The conclusion is simple; you pay for quality care.
Nitric oxide‐releasing polyurethane–PEG copolymer containing the YIGSR peptide promotes endothelialization with decreased platelet adhesion
Authors: Taite Lakeshia J. , Yang Peter , Jun Ho‐Wook , West Jennifer L.
Published: May 2007

Thrombosis and intimal hyperplasia are the principal causes of small‐diameter vascular graft failure. To improve the long‐term patency of polyurethane vascular grafts, we have incorporated both poly(ethylene glycol) and a diazeniumdiolate nitric oxide (NO) donor into the backbone of polyurethane to improve thromboresistance. Additionally, we have incorporated the laminin‐derived cell adhesive peptide sequence YIGSR to encourage endothelial cell adhesion and migration, while NO release encourages endothelial cell proliferation. NO production by polyurethane films under physiological conditions demonstrated biphasic release, in which an initial burst of 70% of the incorporated NO was released within 2 days, followed by sustained release over 2 months. Endothelial cell proliferation in the presence of the NO‐releasing material was increased as compared to control polyurethane, and platelet adhesion to polyethylene glycol‐containing polyurethane was decreased significantly with the addition of the NO donor. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008
Evidence that PI3K, Rac, Rho, and Rho kinase are involved in basic fibroblast growth factor‐stimulated fibroblast–Collagen matrix contraction
Authors: Abe Masatoshi , Sogabe Yoko , Syuto Tomoko , Yokoyama Yoko , Ishikawa Osamu
Published: May 2007

Fibroblast–collagen matrix contraction has been used as a model system to study how cells organize connective tissue. Previous work showed that lysophosphatidic acid (LPA)‐stimulated floating collagen matrix contraction is independent of Rho kinase while platelet‐derived growth factor (PDGF)‐stimulated contraction is Rho kinase‐dependent. The current studies were carried out to determine the signaling mechanisms of basic fibroblast growth factor (bFGF)‐stimulated fibroblast–collagen matrix contraction. Both bFGF and LPA promoted equally collagen matrix contraction well. Three different inhibitors, LY294002 for phosphatidylinositol‐3‐kinase (PI3K), C3 exotransferase for Rho and Y27632 for Rho kinase, suppressed the bFGF‐stimulated fibroblast–collagen matrix contraction. With bFGF stimulation, fibroblasts spread with prominent stress fiber network formation and focal adhesions. In the presence of Rho kinase inhibitor, focal adhesions and stress fibers were mostly lost. We demonstrated that bFGF stimulation for fibroblast caused transient Rac and Rho activation but did not activate Cdc42. In addition, bFGF enhanced fibroblast migration in wound healing assay. The present study implicates PI3K, Rac, Rho, and Rho kinase as being involved in bFGF‐stimulated collagen matrix contraction. The elucidation of bFGF‐triggered signal transduction may be an important clue to understand the roles of bFGF in wound healing. J. Cell. Biochem. 102: 1290–1299, 2007. © 2007 Wiley‐Liss, Inc.
Role of aralar, the mitochondrial transporter of aspartate‐glutamate, in brain N‐acetylaspartate formation and Ca2+ signaling in neuronal mitochondria
Authors: Satrústegui Jorgina , Contreras Laura , Ramos Milagros , Marmol Patricia , del Arco Araceli , Saheki Takeyori , Pardo Beatriz
Published: May 2007

Aralar, the Ca2+‐dependent mitochondrial aspartate‐glutamate carrier expressed in brain and skeletal muscle, is a member of the malate–aspartate NADH shuttle. Disrupting the gene for aralar, SLC25a12, in mice has enabled the discovery of two new roles of this carrier. On the one hand, it is required for synthesis of brain aspartate and N‐acetylaspartate, a neuron‐born metabolite that supplies acetate for myelin lipid synthesis; and on the other, it is essential for the transmission of small Ca2+ signals to mitochondria via an increase in mitochondrial NADH. © 2007 Wiley‐Liss, Inc.
Among the branched‐chain amino acids, only valine metabolism is up‐regulated in astrocytes during glutamate exposure
Authors: Bak Lasse K. , Johansen Maja L. , Schousboe Arne , Waagepetersen Helle S.
Published: May 2007

Glutamate homeostasis during glutamatergic neurotransmission is predominantly maintained via functioning of the glutamate‐glutamine cycle. However, the glutamate‐glutamine cycle explains only the fate of the carbon atoms but not that of the accompanying transfer of nitrogen from neurons to astrocytes. In this respect, a putative branched‐chain amino acid (BCAA) shuttle has been suggested for transfer of amino nitrogen. Metabolism of BCAAs was investigated in cultured cerebellar astrocytes in a superfusion paradigm employing 15N‐labeled leucine, isoleucine, or valine. Some cultures were exposed to pulses of glutamate (50 μM; 10 sec every 2 min; 75 min in total) to mimic conditions during glutamatergic synaptic activity. 15N labeling of glutamate, aspartate, glutamine, alanine, and the three BCAAs was determined by using mass spectrometry. Incorporation of 15N into intracellular glutamate from [15N]leucine, [15N]isoleucine, or [15N]valine amounted to about 40–50% and differed only slightly among the individual BCAAs. Interestingly, label (%) in glutamate from [15N]valine was not decreased upon exposure to exogenous glutamate, which was in contrast to a marked decrease in labeling (%) from [15N]leucine or [15N]isoleucine. This suggests an up‐regulation of transamination involving only valine during repetitive exposure to glutamate. It is suggested that valine in particular might have an important function as an amino acid translocated between neuronal and astrocytic compartments, a function that might be up‐regulated during synaptic activity. © 2007 Wiley‐Liss, Inc.
A systematic review of the evidence for cranberries and blueberries in UTI prevention
Authors: Jepson Ruth G. , Craig Jonathan C.
Published: May 2007

In this review we assess the effectiveness of cranberry and blueberry products in preventing symptomatic urinary tract infections (UTIs). Selection criteria were randomised or quasi‐randomised controlled trials of cranberry or blueberry juice/products for the prevention of symptomatic UTIs. A comprehensive search was undertaken in November 2006 whereupon two reviewers independently assessed and extracted data. Quality was assessed using Cochrane criteria. Relative risks (RR) were calculated where appropriate; otherwise a narrative synthesis was undertaken. No relevant trials of blueberry products were identified. Nine trials of cranberry products met the inclusion criteria. In four good quality randomised controlled trials (RCTs), cranberry products significantly reduced the incidence of symptomatic UTIs in 12 months (overall RR 0.65, 95% CI: 0.46–0.90) compared with placebo/control. Five trials were not included in the meta‐analyses due to the lack of appropriate data. However, only one reported a significant result. Side effects were common, and losses to followup/withdrawals in several of the trials were high (> 40%). There is some evidence from four good quality RCTs that cranberry juice may decrease the number of symptomatic UTIs over a 12‐month period, particularly in women with recurrent UTIs. It is uncertain whether it is effective in other susceptible groups.
Connecticut con‐con
Authors: Davis I. Ridgway
Published: May 2007

Under court pressure, it handles redistricting but party control postpones facing other issues.
Oh, ye of little faith
Authors: Steadman Robert F.
Published: May 2007

Critics of CED's proposals to improve state, local governments told to get their chins up.
A graph theoretic approach to the grouping of ordering data
Authors: Bodin L. D.
Published: May 2007

This paper gives a graph theoretic interpretation of the problem of stratifying ordered data.
Minimum cost routing for dynamic network models
Authors: Yaged B.
Published: May 2007

This paper presents a heuristic technique which attempts to minimize the present worth of first costs (PWFC) needed to satisfy the growth in point‐to‐point flow requirements for a dynamic (in time) model of the long‐haul communications network which spans the United States. This extends earlier work on the design of static (in time) multicommodity flow networks in which each link cost function is a concave function of the link flow. The cost reduction techniques presented here are based upon the coupling between network structure, routing techniques, and economies of scale evident in transmission system costs. The technique does not change any circuit routings performed prior to the study interval. The network model studied is normative, not predictive, and cannot be used to predict the outcome of short range issues (e.g. ‐ impact of rate changes).
Algorithms for a maximum clique and a maximum independent set of a circle graph
Authors: Gavril F.
Published: May 2007

Consider a family of chords in a circle. A circle graph is obtained by representing each chord by a vertex, two vertices being connected by an edge when the corresponding chords intersect. In this paper, we describe efficient algorithms for finding a maximum clique and a maximum independent set of circle graphs. These algorithms require at most n3 steps, where n is the number of vertices in the graph.
Cost allocation in networks: The bulk supplier problem
Authors: Claus A. , Kleitman D. J.
Published: May 2007

We consider the cost allocation problem faced by a large scale supplier (the telephone company) who rents telephone circuits to its customers. A number of possible allocation rate structures are analyzed, as are some of the criteria that they may be measured by. Finally, we draw conclusions and make recommendations for cost allocation in these circumstances.
On building minimum cost communication networks over time
Authors: Zadeh N.
Published: May 2007

This paper deals with the problem of minimizing the present worth of expenditures needed to enlarge the capacity of a communications network over time so as to meet rising traffic demands. Eight general “tests” are given for improving network solutions. The tests require only a moderate amount of computation and have the property that they will improve a wide class of non‐optimal solutions. It is observed that for a large subclass of practical problems, the dynamic problem of building a network over time may be converted to a static problem for most of the computations. This suggests a strong similarity between the optimal solutions to both problems.
On general routing problems
Authors: Lenstra J. K. , Kan A. H. G. Rinnooy
Published: May 2007

In two recent papers by C. S. Orloff (Networks, 4(1974)35–64, 147–162) general routing problems for one or more vehicles on a graph G = (N,A) are introduced and discussed. The single vehicle problem is to find an optimal tour on G, containing required subsets Q ⊆ N and R ⊆ A. We show that a proposed conversion of required nodes to required arcs is not allowed and that the problem remains polynomial complete if Q = θ. Furthermore, the proposed transformations from M vehicle to single vehicle problems are shown to be incorrect; correct transformations are presented as well.
On optimum path problems
Authors: Thomas R. E.
Published: May 2007

This tutorial paper is concerned with network problems characterized as finding optimum paths in given networks and with synthesizing networks with given optimum paths. Optimum paths are best with respect to path weights where the path weights can represent such‐diverse path parameters as distances, costs, flows, or reliabilities. This paper surveys these problems and the known results by considering specific but simple generic examples while avoiding any detailed or rigorous proofs. The final example uses a mathematical equivalence and combines known optimum path results to obtain new results regarding the synthesis of optimum networks with specified point‐to‐point reliabilities.
A good algorithm for smallest spanning trees with a degree constraint
Authors: Gabow H. N.
Published: May 2007

Given a connected graph with edge costs, we seek a spanning tree having a specified degree at one vertex r, with cost as small as possible. A previous algorithm, using edge exchanges, has run time 0(V2); we improve this to 0(E log log V+V log V). Here V and E are the number of vertices and edges. The algorithm uses edge exchanges ordered efficiently on a reduced graph; it also uses efficient algorithms for minimum spanning trees and priority queues.
A note on finding optimum branchings
Authors: Camerini P. M. , Fratta L. , Maffioli F.
Published: May 2007

The subject of this note is Tarjan's algorithm for finding an optimum branching in a directed graph. Two errors are pointed out, namely (i) an incorrect claim involving branching uniqueness, and (ii) an imprecise way of updating edge values in each iteration. These two inaccuracies do not affect the basic validity of the algorithm. It is shown here that they may be fixed via a simple modification, which leaves unchanged the overall time and space performances.
An integer linear programming approach to the steiner problem in graphs
Authors: Aneja Y. P.
Published: May 2007

Consider a connected undirected graph G[N; E] with N = S ∪ P, the set of nodes, where P is designated as the set of Steiner points. A weight is associated with each edge ei of the set E. The problem of obtaining a minimal weighted tree which spans the set S of nodes has been termed in literature as the Steiner problem in graphs. A specialized integer programming (set covering) formulation is presented for the problem. The number of constraints in this formulation grows exponentially with the size of the problem. A method called the row generation scheme is developed to solve the above problem. The method requires knowing the constraints only implicitly. Several other problems which can be put in a similar framework can also be handled by the above scheme. The generality of the scheme and its efficiency is discussed. Finally the computational result is demonstrated.
Graphs as models of communication network vulnerability: Connectivity and persistence
Authors: Boesch Frank T. , Harary Frank , Kabell Jerald A.
Published: May 2007

It is well known that the maximum connectivity k of a graph G with p points and q lines is given by [2 q/p]. This is restated in two useful alternative forms which minimize q given p and k, and which maximize p in terms of q and k. We define the persistence of a graph as the smallest number of points whose removal increases the diameter. It is shown that the persistence of a graph of diameter d is the minimum over all pairs of nonadjacent points of the maximum number of disjoint paths of length at most d joining them. A similar result is obtained for line‐persistence and it is shown that these invariants are independent of each other.
The cohesiveness of a point of a graph
Authors: Akiyama Jin , Boesch Frank , Era Hiroshi , Harary Frank , Tindell Ralph
Published: May 2007

The connectivity contribution or cohesiveness of a point v of graph G is defined as the difference k(G) ‐ k(G ‐ v) where kappa is the usual connectivity symbol. It is shown that if a point v of G has negative cohesiveness, then the set of points adjacent to v is the unique minimum size disconnecting set of G. This theorem has several corollaries including the result that if v has negative cohesiveness in G, then it does not in Γ. Finally we define a cohesiveness triple (n_, n0, n+) of a graph by taking these, respectively, as the number of negative, zero, and positive cohesiveness points of G. The necessary and sufficient conditions for an arbitrary triple to be the cohesiveness triple of a graph are derived.
Mean flow scheduling and optimal construction of a treelike communication network
Authors: Perl Yehoshua , Yesha Yaacov
Published: May 2007

Horn's algorithm for weighted mean flow scheduling with treelike precedence constraints is reexamined. A new analysis of an efficient implementation of Horn's algorithm shows an O(n log n) complexity. This is an improvement on the known O(n2) complexity of this algorithm. An application of Horn's algorithm to a problem of optimal scheduling of a treelike communication network is presented.
Complexity of vehicle routing and scheduling problems
Authors: Lenstra J. K. , Kan A. H. G. Rinnooy
Published: May 2007

The complexity of a class of vehicle routing and scheduling problems is investigated. We review known NP‐hardness results and compile the results on the worst‐case performance of approximation algorithms. Some directions for future research are suggested. The presentation is based on two discussion sessions during the Workshop to Investigate Future Directions in Routing and Scheduling of Vehicles and Crews, held at the University of Maryland at College Park, June 4–6, 1979.
Series‐parallel reduction for difficult measures of network reliability
Authors: Rosenthal Arnon
Published: May 2007

Formulas for series and parallel reductions are obtained for difficult measures of network reliability. Examples considered include “traffic to center,” “total traffic carried,” “minimum cut,” and “all demanding vertices communicate.” We find general properties of “distribution‐preserving” and “average‐preserving” replacements, and present several examples. For systems analyzed by Monte‐Carlo sampling, we find that the estimator variance is reduced by the replacement.
A new approach to near‐optimal path assignment through electric‐circuit modeling
Authors: Smolleck Howard A. , Chen Mo‐Shing
Published: May 2007

This paper introduces a new philosophy and an associated computational algorithm for obtaining near‐optimal path assignments in a connected network. The method, which differs completely from traditional and other currently used techniques, is based upon the performance of successive computational examinations of the distribution of currents in the electric‐circuit model of the network under observation. Fast sparse‐matrix techniques originally developed for real‐time studies in the electric power sector are introduced in order to make the algorithm feasible for large‐system applications.

Small illustrative examples are presented, and observations concerning the use of the authors' algorithm in the solution of a large transportation system problem are discussed. Some unique characteristics of the algorithm are explored.
Aggregation and disaggregation in convex network problems
Authors: Zipkin Paul H.
Published: May 2007

This article considers the error induced when the nodes of a large convex‐cost network problem are aggregated to form a smaller problem. First, I formalize the notion of aggregation, focusing on disaggregation of the solution and construction of the cost functions of the aggregate problem. I then explore qualitatively the conditions under which the error is likely to be small, and show how to compute bounds on the error.
An optimal 2‐FT realization of binary symmetric hierarchical tree systems
Authors: Kwan C. L. , Toida S.
Published: May 2007

Fault tolerance is expected to become the major concern for complex systems consisting of many computing or processing units. Given a basic nonredundant system of computing units, the problems are to determine the minimum extra units and connections required and their structures so that the resulting system would tolerate k faulty units. These problems have been formulated and solved for some special types of systems by Hayes using a graph model. In this paper, we present a procedure for designing an optimal 2‐FT (two‐fault‐tolerant) structure for binary symmetric hierarchical tree systems.
Modular decomposition and reliability computation in stochastic transportation networks having cutnodes
Authors: Shogan Andrew W.
Published: May 2007

Consider a flow network having random arc capacities and having associated with each node n a “supply‐demand random variable” Yn whose absolute value equals the supply available at the node when Yn assumes a non‐negative value and the demand required by the node when Yn assumes a nonpositive value. A fundamental problem is the computation of the reliability R, that is, the probability that the random variables will assume values that permit a feasible flow. Upon adapting the graph‐theoretic concepts of “cutnode” and “block,” it is possible to identify a “block‐module,” an independent, nontrivial subnetwork that has one and only one node (the “cutnode”) connected to nodes outside the subnetwork. The reliability of the network will increase by a known factor after a “block‐modular decomposition” that consists of a transformation of the cutnode's supply‐demand random variable and the deletion of the remainder of the block module. Provided the original network possesses at least one block module, R can be determined from a sequence of block‐modular decompositions that reduce the original network to a single node whose reliability is easily computed. Computational experience with a computer implementation of such a decomposition method is reported, and the application of the method to the analysis of electrical power networks is included.
The complexity of finding maximum disjoint paths with length constraints
Authors: Itai A. , Perl Y. , Shiloach Y.
Published: May 2007

The following problem is considered: Given an integer K, a graph G with two distinct vertices s and t, find the maximum number of disjoint paths of length K from s to t. The problem has several variants: the paths may be vertex‐disjoint or edge‐disjoint, the lengths of the paths may be equal to K or bounded by K, the graph may be undirected or directed. It is shown that except for small values of K all the problems are NP‐complete. Assuming P ≠ NP, for each problem, the largest value of K for which the problem is not NP‐complete is found. Whenever a polynomial algorithm exists, an efficient algorithm is described.
Polynomial algorithms for estimating network reliability
Authors: Zemel Eitan
Published: May 2007

We consider the problem of calculating the best possible bounds on the reliability of a system given limited information about the joint density function of its components. We show that a polynomial algorithm for this problem exists iff such an algorithm exists for a certain related problem of minimizing a linear objective function over a clutter. We give numerous examples of network as well as other problems for which the algorithm runs in polynomial time. We also use our construction to prove NP‐hardness for others.
A procedure for dispatching moving mobile servers
Authors: Berman O. , Rahnama M. Rasty
Published: May 2007

This article deals with some dispatching aspects of a system in which the dispatcher, in addition to stationary service units, has also the option to assign service units in motion. The nonstationary servers leave their home location at different times and move on different paths. The response time is the shortest time path of a server from the incident. The objective is to identify efficiently the appropriate unit to dispatch to a random incident. The analysis ends as soon as one of the servers is dispatched. The paper contains an efficient procedure based on the notion of the general time path. The general time path is a single path in which we superimpose the various different paths of all the moving servers. This simplifies the analysis since once the general time path is constructed it contains all the information that is provided by all those different paths. The procedure shows how to divide the general time path to disjoint segments according to the server which is closest to the incident (in each one of the segments exactly one identifiable server is closest to the incident).
Constructing a minimal‐cost spanning tree subject to resource constraints and flow requirements
Authors: Shogan Andrew W.
Published: May 2007

Consider a network in which one node is a source having an infinite supply of a commodity, and every other node is a sink having a known constant demand. Furthermore, associated with each potential arc of the network are the following known constants: the cost of constructing the arc, the amount of each scarce resource consumed during the construction of the arc, and the flow capacity of the arc. Given the above known constants as well as the available supply of each of the scarce resources, the problem is to construct a minimal‐cost spanning tree subject to the limitations on the consumption of the scarce resources and the requirement that there exists a flow from the source satisfying the demands at the sinks without exceeding any arc capacity. This paper discusses the solution of such a problem by a branch and bound algorithm based on Lagrangian relaxation. Also included are applications of the problem, extensions of the problem, and a report on preliminary computational experience with a computer implementation of the algorithm.
An algorithm for finding a large independent set in planar graphs
Authors: Chiba Norishige , Nishizeki Takao , Saito Nobuji
Published: May 2007

A subset of the vertices of a graph is independent if no two vertices in the set are adjacent. M. O. Albertson proposed an algorithm for finding an independent set that contains more than two‐ninth of the vertices of a planar graph. Refining his algorithm, we give an O(n2) algorithm for the same purpose.
I‐Colorings, I‐Phasings, and I‐Intersection assignments for graphs, and their applications
Authors: Opsut Robert J. , Roberts Fred S.
Published: May 2007

This paper studies set assignments on graphs, functions assigning a set S(x) to each vertex x of a graph, and specifically set assignments where each set is a real interval, perhaps of specified minimum length. Such set assignments arise in applied problems dealing with fleet maintenance, mobile radio frequency assignment, task assignment, traffic phasing, banquet preparation, and computer storage optimization. These problems are briefly discussed. They are translated into problems of finding a set coloring [a set assignment in which an edge between x and y implies that S(x) and S(y) are disjoint], a set phasing [a set coloring of the complementary graph], or a set intersection assignment. The paper presents methods for finding set colorings, phasings, and intersection assignments in which the measure of the union of the intervals S(x) is minimized or in which the sum of the lengths of the S(x) is maximized.
Dynamic matchings and quasidynamic fractional matchings. II
Authors: Orlin James B.
Published: May 2007

Consider a directed graph G in which every edge has an associated real‐valued distance and a real‐valued weight. The weight of an undirected circuit of G is the sum of the weights of the edges, whereas the distance of an undirected circuit is the sum of the distances of the forward edges of the circuit minus the sum of the distances of the backward edges. A trivial circuit is a two‐edge circuit in which one edge of G appears twice on the circuit. A quasidynamic fractional matching (or Q‐matching) is a collection of vertex‐disjoint circuits such that each circuit is either trivial or else it is an odd circuit whose distance is nonzero. The G‐matching problem is to find a Q‐matching that maximizes the sum of the weights of its circuits. The Q‐matching problem generalizes both the matching problem and the fractional matching problem. Moreover, the dynamic matching problem, which is a matching problem on an infinite dynamic (time‐expanded) graph, is linearly transformable to the Q‐matching problem, as shown in Part I of this paper. In this paper we solve the Q‐matching problem by generalizing Edmonds' blossom algorithm. In fact, all of the major components of the blossom algorithm‐including alternating trees, augmentations, shrinking, and expanding‐are appropriately generalized to yield a running time that is proportional to that for the weighted matching problem. Furthermore, if all edge distances are equal to zero, this new algorithm reduces to the blossom algorithm.
A special spatial equilibrium problem
Authors: Pang Jong‐Shi , Yu Chang‐Sung
Published: May 2007

In this paper, we study a special single‐commodity spatial equilibrium problem. We show how the problem is related to a shortest‐path problem and develop a simple algorithm for its solution. We also discuss an extension of the single‐commodity problem to a multicommodity problem.
On multicommodity flows in planar graphs
Authors: Hassin Refael
Published: May 2007

Okamura and Seymour recently proved two properties of multicommodity flows in undirected planar networks where all the sources and the sinks are on a common face of the underlying graph. One is that a feasible solution is guaranteed whenever each cut's capacity is at least as large as the cut's demand. The second is that if all demands and capacities are integers then the flow values may be chosen half‐integer‐valued. In this paper we use the first property to construct two computational procedures; one examines the existence of a feasible flow, and the other constructs such a flow if one exists. We also show that the construction procedure can be used as an alternative proof to the above properties. Finally we show, by presenting counterexamples, that the half‐integrality property does not necessarily hold when either the graph cannot be drawn in the plane with all sources and sinks on a common face, or the graph is directed.