bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantifying the evidence for biodiversity effects on ecosystem functioning and services
Authors: Balvanera Patricia , Pfisterer Andrea B. , Buchmann Nina , He Jing‐Shen , Nakashizuka Tohru , Raffaelli David , Schmid Bernhard
Published: August 2006

Concern is growing about the consequences of biodiversity loss for ecosystem functioning, for the provision of ecosystem services, and for human well being. Experimental evidence for a relationship between biodiversity and ecosystem process rates is compelling, but the issue remains contentious. Here, we present the first rigorous quantitative assessment of this relationship through meta‐analysis of experimental work spanning 50 years to June 2004. We analysed 446 measures of biodiversity effects (252 in grasslands), 319 of which involved primary producer manipulations or measurements. Our analyses show that: biodiversity effects are weaker if biodiversity manipulations are less well controlled; effects of biodiversity change on processes are weaker at the ecosystem compared with the community level and are negative at the population level; productivity‐related effects decline with increasing number of trophic links between those elements manipulated and those measured; biodiversity effects on stability measures (‘insurance’ effects) are not stronger than biodiversity effects on performance measures. For those ecosystem services which could be assessed here, there is clear evidence that biodiversity has positive effects on most. Whilst such patterns should be further confirmed, a precautionary approach to biodiversity management would seem prudent in the meantime.
Determining the identity and roles of oil‐metabolizing marine bacteria from the Thames estuary, UK
Authors: McKew Boyd A. , Coulon Frédéric , Osborn A. Mark , Timmis Kenneth N. , McGenity Terry J.
Published: August 2006

Crude oil is a complex mixture of different hydrocarbons. While diverse bacterial communities can degrade oil, the specific roles of individual members within such communities remain unclear. To identify the key bacterial taxa involved in aerobic degradation of specific hydrocarbons, microcosm experiments were established using seawater from Stanford le Hope, Thames estuary, UK, adjacent to a major oil refinery. In all microcosms, hydrocarbon degradation was significant within 10 weeks, ranging from > 99% of low‐molecular‐weight alkanes (C10–C18), 41–84% of high‐molecular‐weight alkanes (C20–C32) and pristane, and 32–88% of polycyclic aromatic hydrocarbons (PAHs). Analysis of 16S rRNA sequences from clone libraries and denaturing gradient gel electrophoresis (DGGE) indicated that, except when incubated with fluorene, PAH‐degrading communities were dominated by Cycloclasticus. Moreover, PAH‐degrading communities were distinct from those in microcosms containing alkanes. Degradation of the branched alkane, pristane, was carried out almost exclusively by Alcanivorax. Bacteria related to Thalassolituus oleivorans (99–100% identity) were the dominant known alkane degraders in n‐alkane (C12–C32) microcosms, while Roseobacter‐related bacteria were also consistently found in these microcosms. However, in contrast to previous studies, Thalassolituus, rather than Alcanivorax, was dominant in crude oil‐enriched microcosms. The communities in n‐decane microcosms differed from those in microcosms supplemented with less volatile alkanes, with a phylogenetically distinct species of Thalassolituus out‐competing T. oleivorans. These data suggest that the diversity and importance of the genus Thalassolituus is greater than previously established. Overall, these experiments demonstrate how degradation of different petroleum hydrocarbons is partitioned between different bacterial taxa, which together as a community can remediate petroleum hydrocarbon‐impacted estuarine environments.
Effects of temperature and biostimulation on oil‐degrading microbial communities in temperate estuarine waters
Authors: Coulon Frédéric , McKew Boyd A. , Osborn A. Mark , McGenity Terry J. , Timmis Kenneth N.
Published: August 2006

Improved strategies for oil‐spill remediation will follow a better understanding of the nature, activities and regulating parameters of petroleum hydrocarbon‐degrading microbial communities in temperate marine environments. The addition of crude oil to estuarine water resulted in an immediate change in bacterial community structure, increased abundance of hydrocarbon‐degrading microorganisms and a rapid rate of oil degradation, suggesting the presence of a pre‐adapted oil‐degrading microbial community and sufficient supply of nutrients. Relatively rapid degradation was found at 4°C, the lowest temperature tested; and it was temperature rather than nutrient addition that most influenced the community structure. A detailed phylogenetic analysis of oil‐degrading microcosms showed that known hydrocarbonoclastic organisms like Thalassolituus and Cycloclasticus, as well as proposed oil degraders like Roseobacter, were present at both 4°C and 20°C, demonstrating the thermo‐versatility of such organisms. Clones related to Oleispira antarctica (98% 16S rRNA similarity), a psychrophilic alkane degrader, were dominant in the 4°C oil‐degrading community, whereas other clones constituting a different clade and showing 94% similarity 16S rRNA with O. antarctica were found in situ. These findings demonstrate the potential for intrinsic bioremediation throughout the course of the year in temperate estuarine waters, and highlight the importance of both versatile psychrotolerant and specialized psychrophilic hydrocarbon‐degrading microbes in effecting this process at low temperatures.
A prospective evaluation of occult disorders in obstructed defecation using the ‘iceberg diagram’
Authors: Pescatori M. , Spyrou M. , Pulvirenti d'Urso A.
Published: August 2006

Objective  Surgical treatment of constipation and obstructed defecation (OD) carries frequent recurrences, as OD is an ‘iceberg syndrome’ characterized by ‘underwater rocks’ or occult diseases which may affect the outcome of surgery. The aim of this study was to evaluate occult disorders, in order to alert the clinician of these and minimize failures.

Method  One hundred consecutive constipated patients with OD symptoms, 81 women, median age 52 years, underwent perineal examination, proctoscopy, anorectal manometry and anal/vaginal ultrasound (US). Anorectal physiology and imaging tests were also carried out when indicated, as well as psychological and urogynaecological consultations. Symptoms were graded using a modified 1–20 constipation score. Both evident (e.g. rectocele) and occult (e.g. anismus) diseases were prospectively evaluated using a novel ‘iceberg diagram’. The type of treatment, whether conservative or surgical, was also recorded.

Results  Fifty‐four (54%) patients had both mucosal prolapse and rectocele. All patients had at least two occult OD‐related diseases, 66 patients had at least three of them: anxiety–depression, anismus and rectal hyposensation were the most frequent (66%, 44% and 33%, respectively). The median constipation score was 11 (range 2–20), the median number of ‘occult disorders’ was 5 (range 2–8). Conservative treatment was carried out in most cases. Surgery was carried out in 14 (14%) patients.

Conclusion  The novel ‘iceberg diagram’ allowed the adequate evaluation of OD‐related occult diseases and better selection of patients for treatment. Most were managed conservatively, and only a minority were treated by surgery.
Acute hyperglycaemia does not alter coronary vascular function in isolated, perfused rat hearts
Authors: Klabunde R. E. , Ryan K. M. , Paxson C. E.
Published: August 2006

Aim:  The purpose of this study was to evaluate the hypothesis that acute hyperglycaemia in hearts of rats without diabetes alters coronary vascular responses to nitric oxide (NO), adenosine (ADO) and phenylephrine (PHE).

Methods:  Coronary function was studied in isolated, Langendorff‐perfused, non‐beating rat hearts that were perfused with an oxygenated Krebs–Henseleit solution containing 40 mM KCl to arrest the hearts. Changes in coronary vascular resistance were assessed by measuring changes in coronary perfusion pressure under constant flow conditions. Coronary responses to ADO, sodium nitroprusside (SNP), PHE and L‐NAME (inhibitor of NO synthase) were studied either under normoglycaemic conditions (100 mg/dl d‐glucose) or after 60 min of hyperglycaemic perfusion (500 mg/dl d‐glucose). d‐mannitol was used as a hyperosmotic control.

Results:  Hyperglycaemia did not alter vasodilator responses to ADO or SNP in the presence or absence of L‐NAME. Furthermore, hyperglycaemia, compared with normoglycaemia, did not alter vasoconstrictor responses induced by L‐NAME or PHE.

Conclusions:  Sixty minutes of exposure to 500 mg/dl of d‐glucose in an isolated, non‐beating, buffer‐perfused rat heart did not significantly affect coronary vascular smooth muscle vasodilator responses to NO and ADO or alter α1‐adrenoceptor‐mediated vasoconstrictor responses to PHE. Furthermore, an unchanged vasoconstrictor response to L‐NAME suggests that acute hyperglycaemia did not alter NO bioavailability.
Corporate Entrepreneurship Activities through Strategic Alliances: A Resource‐Based Approach toward Competitive Advantage*
Authors: Teng Bing‐Sheng
Published: August 2006

abstract  Corporate entrepreneurship (CE) activities may significantly benefit from interfirm strategic alliances, although such benefits have not been sufficiently examined in the literature. In this paper, a resource‐based framework is presented to examine how strategic alliances offer entrepreneurial firms needed resources that may not otherwise be available. We argue that CE activities are likely to lead to resource gaps. We compare various options to fill resource gaps, and identify the pros and cons of the alliance approach. We then discuss the resource conditions that provide competitive advantage for a firm, if alliances are properly used to help implement CE. Finally, we examine how different types of alliance (e.g. joint ventures, R&D alliances, and learning alliances) facilitate various CE activities, including innovation, corporate venturing, and strategic renewal.
On the Demonstration of Blindsight in Monkeys
Authors: CHRISTOPHER MOLE , SEAN DORRANCE KELLY
Published: August 2006

Abstract:  The work of Alan Cowey and Petra Stoerig is often taken to have shown that, following lesions analogous to those that cause blindsight in humans, there is blindsight in monkeys. The present paper reveals a problem in Cowey and Stoerig’s case for blindsight in monkeys. The problem is that Cowey and Stoerig’s results would only provide good evidence for blindsight if there is no difference between their two experimental paradigms with regard to the sorts of stimuli that are likely to come to consciousness. We show that the paradigms could differ in this respect, given the connections that have been shown to exist between working memory, perceptual load, attention, and consciousness.
Educational Investments in a Dual Economy
Authors: MUDE ANDREW G. , BARRETT CHRISTOPHER B. , McPEAK JOHN G. , DOSS CHERYL R.
Published: August 2006

We present a simple two‐period, dual‐economy model in which migration options may affect the informal financing of educational investments. When credit contracts are universally available and perfectly enforceable, spatially varied returns to human capital have no effect on educational investment patterns. But when financial markets are incomplete and informal mechanisms with imperfect contract enforcement must fill the breach, attributes that affect the returns to education will affect educational lending and, consequently, educational attainment. Migration options can increase the returns to education, but can also choke off the informal finance on which poorer rural households may depend for long‐term, lumpy investments like children's education.
Spectrum of Mutations in the CFTR Gene in Cystic Fibrosis Patients of Spanish Ancestry
Authors: Alonso M. J. , Heine‐Suñer D. , Calvo M. , Rosell J. , Giménez J. , Ramos M. D. , Telleria J. J. , Palacio A. , Estivill X. , Casals T.
Published: August 2006

We analyzed 1,954 Spanish cystic fibrosis (CF) alleles in order to define the molecular spectrum of mutations in the CFTR gene in Spanish CF patients. Commercial panels showed a limited detection power, leading to the identification of only 76% of alleles. Two scanning techniques, denaturing gradient gel electrophoresis (DGGE) and single strand conformation polymorphism/hetroduplex (SSCP/HD), were carried out to detect CFTR sequence changes. In addition, intragenic markers IVS8CA, IVS8‐6(T)n and IVS17bTA were also analyzed. Twelve mutations showed frequencies above 1%, p.F508del being the most frequent mutation (51%). We found that eighteen mutations need to be studied to achieve a detection level of 80%. Fifty‐one mutations (42%) were observed once. In total, 121 disease‐causing mutations were identified, accounting for 96% (1,877 out of 1,954) of CF alleles. Specific geographic distributions for the most common mutations, p.F508del, p.G542X, c.1811 + 1.6kbA > G and c.1609delCA, were confirmed. Furthermore, two other relatively common mutations (p.V232D and c.2789 + 5G > A) showed uneven geographic distributions. This updated information on the spectrum of CF mutations in Spain will be useful for improving genetic testing, as well as to facilitate counselling in people of Spanish ancestry. In addition, this study contributes to defining the molecular spectrum of CF in Europe, and corroborates the high molecular mutation heterogeneity of Mediterranean populations.
Attentional blink and prepulse inhibition of startle are positively correlated
Authors: Cornwell Brian R. , Echiverri Aileen M. , Grillon Christian
Published: August 2006

Although a link between the attentional blink and prepulse startle inhibition has been considered, no evidence of this relationship has been reported. We delivered acoustic startle probes during rapid serial visual presentations in which the relative positions of two targets (targets 1 and 2) was varied within a stream of distractors. Startle probes were presented at 100 ms lead intervals relative to onset of a target or distractor. We found positive correlations between visual prepulse inhibition and attentional blink effects across participants. As the magnitude of prepulse inhibition with target and distractor lead stimuli increased, deficits in identifying target 2 during the attentional blink increased, suggesting similar processes underlying these phenomena. Whereas prepulse inhibition may reveal the strength of inhibition to protect stimulus processing, attentional blink may index the rate of recovery from similar inhibitory processes.
Electromyographic responses to static and dynamic avatar emotional facial expressions
Authors: Weyers Peter , Mühlberger Andreas , Hefele Carolin , Pauli Paul
Published: August 2006

Facial muscular reactions to avatars' static (neutral, happy, angry) and dynamic (morphs developing from neutral to happy or angry) facial expressions, presented for 1 s each, were investigated in 48 participants. Dynamic expressions led to better recognition rates and higher intensity and realism ratings. Angry expressions were rated as more intense than happy expressions. EMG recordings indicated emotion‐specific reactions to happy avatars as reflected in increased M. zygomaticus major and decreased M. corrugator supercilii tension, with stronger reactions to dynamic as compared to static expressions. Although rated as more intense, angry expressions elicited no significant M. corrugator supercilii activation. We conclude that facial reactions to angry and to happy facial expressions hold different functions in social interactions. Further research should vary dynamics in different ways and also include additional emotional expressions.
Nerve growth factor‐induced phosphorylation of amphiphysin‐1 by casein kinase 2 regulates clathrin–amphiphysin interactions
Authors: Döring Markus , Loos Anneke , Schrader Nina , Pfander Boris , Bauerfeind Rudolf
Published: August 2006

Amphiphysins interact directly with clathrin and have a function in clathrin‐mediated synaptic vesicle recycling and clathrin‐mediated endocytosis. The neuronal isoform amphiphysin‐1 is a serine/threonine phosphoprotein that is dephosphorylated upon stimulation of synaptic vesicle endocytosis. Rephosphorylation was stimulated by nerve growth factor. We analysed the regulation of amphiphysin–clathrin interactions by phosphorylation. The N‐terminal domain of clathrin bound to unphosphorylated amphiphysin‐1, but not to the phosphorylated protein. A search for possible phosphorylation sites revealed two casein kinase 2 consensus motifs in close proximity to the clathrin binding sites in amphiphysin‐1 and ‐2. We mutagenized these residues (T350 and T387) to glutamate, mimicking a constitutive phosphorylation. The double mutant showed a strong reduction in clathrin binding. The assumption that casein kinase 2 phosphorylates amphiphysin‐1 at T350 and T387 was corroborated by experiments showing that: (i) casein kinase 2 phosphorylated these residues directly in vitro, (ii) when expressed in HeLa cells, the glutamate mutant showed reduced phosphorylation, and (iii) casein kinase 2 inhibitors blocked nerve growth factor‐induced phosphorylation of endogenous amphiphysin‐1 in PC12 cells. These observations are consistent with the hypothesis that, upon activation by nerve growth factor, casein kinase 2 phosphorylates amphiphysin‐1 and thereby regulates the endocytosis of clathrin‐coated vesicles via the interaction between clathrin and amphiphysin.
Synaptic and vesicular co‐localization of the glutamate transporters VGLUT1 and VGLUT2 in the mouse hippocampus
Authors: Herzog Etienne , Takamori Shigeo , Jahn Reinhard , Brose Nils , Wojcik Sonja M.
Published: August 2006

Vesicular glutamate transporters (VGLUTs) are essential to glutamatergic synapses and determine the glutamatergic phenotype of neurones. The three known VGLUT isoforms display nearly identical uptake characteristics, but the associated expression domains in the adult rodent brain are largely segregated. Indeed, indirect evidence obtained in young VGLUT1‐deficient mice indicated that in cells that co‐express VGLUT1 and VGLUT2, the transporters may be targeted to different synaptic vesicles, which may populate different types of synapses formed by the same neurone. Direct evidence for a systematic segregation of VGLUT1 and VGLUT2 to distinct synapses and vesicles is lacking, and the mechanisms that may convey this segregation are not known. We show here that VGLUT1 and VGLUT2 are co‐localized in many layers of the young hippocampus. Strikingly, VGLUT2 co‐localizes with VGLUT1 in the mossy fibers at early stages. Furthermore, we show that a fraction of VGLUT1 and VGLUT2 is carried by the same vesicles at these stages. Hence, hippocampal neurones co‐expressing VGLUT1 and VGLUT2 do not appear to sort them to separate vesicle pools. As the number of transporter molecules per vesicle affects quantal size, the developmental window where VGLUT1 and VGLUT2 are co‐expressed may allow for greater plasticity in the control of quantal release.
Isolation and characterization of eight microsatellite loci for the study of gene flow between Testudo marginata and Testudo weissingeri (Testudines: Testudinidae)
Authors: PEREZ MELANIE , BOUR ROGER , LAMBOURDIERE JOSIE , SAMADI SARAH , BOISSELIER MARIE‐CATHERINE
Published: August 2006

The taxonomic status of the Greek Testudo species, marginated tortoise (Testudo marginata Schoepff, 1793) and dwarf marginated tortoise (Testudo weissingeri Bour, 1995), is controversed. In order to study the gene flow among these Greek Testudo species, eight polymorphic microsatellite markers were characterized and screened for 32 individuals. The number of alleles observed per locus ranged from two to 19. Observed heterozygosities varied from 0.235 to 0.830. These microsatellite loci were also successfully tested on seven closely related species of Testudinidae. This set of microsatellites offers an efficient tool to investigate genetic differentiation among testudinid species.
Characterization of six polymorphic microsatellite loci from Ampelomyces quisqualis, intracellular mycoparasite and biocontrol agent of powdery mildew
Authors: HARVEY N. G.
Published: August 2006

Ampelomyces spp. are common intracellular mycoparasites of powdery mildews worldwide and a strain has been commercialized as a biocontrol agent against these plant pathogens. In light of recent genetic analyses revealing high internal transcribed spacer sequence variability among Ampelomyces strains on different host plant mildews, yet no sequence variability within the Malus strain, polymorphic microsatellites were required to permit biocontrol and ecological studies of the complex apple/apple mildew/Ampellomyces tritrophic interaction. For this purpose, described here are the primers to amplify six polymorphic microsatellite loci from Ampelomyces quisqualis isolated from mycelia of the apple powdery mildew fungus, Podosphaera leucotricha.
Development of microsatellite markers in a mangrove tree species Aegiceras corniculatum (Myrsinaceae)
Authors: GENG Q. F. , LIAN C. L. , TAO J. M. , QIU R. L. , HOGETSU T.
Published: August 2006

Aegiceras corniculatum is an ecologically important mangrove tree species. We isolated 18 polymorphic microsatellite loci from this species. These loci provided microsatellite markers with polymorphism of two to eight alleles per locus. The observed and expected heterozygosities ranged from 0.050 to 0.550, and from 0.097 to 0.736, respectively. These markers will contribute to research on the conservation, genetic diversity and mating patterns of A. corniculatum.
Development of 21 microsatellite loci for puma (Puma concolor) ecology and forensics
Authors: KURUSHIMA JENNIFER D. , COLLINS JULIA A. , WELL JAY A. , ERNEST HOLLY B.
Published: August 2006

We developed 21 microsatellite (13 dinucleotide and 8 tetranucleotide) primers specifically for pumas (Puma concolor). The primers were tested across 243 individuals from California and Nevada, and displayed an average of 5.5 alleles per locus. Previously, domestic cat (Felis catus) primers have been adapted for puma genetic studies. Puma‐specific loci may reduce concerns associated with ascertainment bias, improve genetic structure resolution and provide additional tetranucleotide loci valuable for forensic applications. These puma‐specific microsatellites will aid studies involving parentage, kinship and population structure, along with forensic case applications including poaching and puma‐associated injuries to humans and domestic animals.
Isolation and characterization of polymorphic microsatellite markers of Anopheles sinensis, a malaria vector mosquito in the East Asia region
Authors: JUNG J. , LEE E. , KIM W.
Published: August 2006

Eleven polymorphic dinucleotide (GA and CA) microsatellites were isolated and characterized in the mosquito Anopheles sinensis; this species is distributed over the East Asia region and is a primary vector of malaria, particularly in Korea. The number of alleles per locus ranged from 4 to 13. The observed heterozygosity (HO) and expected heterozygosity (HE) varied from 0.30 to 0.89 and from 0.59 to 0.90, respectively. These microsatellites could be useful in studying the evolution of the widely distributed A. sinensis in diverse environments.
Development and characterization of microsatellite loci from Olea europaea
Authors: GIL F. SABINO , BUSCONI M. , DA CÂMARA MACHADO A. , FOGHER C.
Published: August 2006

This study reports 19 simple sequence repeat loci developed from a genomic library of the olive tree (Olea europaea L.), of which 12 revealed to be polymorphic and informative, ranging from two to 14 alleles.
MICROFAMILY (version 1): a computer program for detecting flanking‐region similarities among different microsatellite loci
Authors: MEGLÉCZ EMESE
Published: August 2006

Microsatellite flanking regions are not necessarily unique sequences, but they may group into sequence families. Microsatellites occurring within such families are likely to give multiple banding patterns during polymerase chain reaction amplifications. microfamily (version 1) is a program that detects flanking‐region similarities between different microsatellite‐containing sequences, thus allowing for potentially problematic sequences to be eliminated prior to primer design. The program also accomplishes some otherwise tedious sequence editing, such as checking for nonpermitted characters, and eliminates poorly readable extremities or potential vector/adapter contamination.

microfamily is written in Perl and available for Linux and Windows systems at http://www.up.univ‐mrs.fr/local/egee/dir/meglecz/microfamily.html.
House Finch Carpodacus mexicanus roosting behaviour during the non‐breeding season and possible effects of mycoplasmal conjunctivitis
Authors: DHONDT ANDRÉ A. , DRISCOLL MELANIE J. L. , SWARTHOUT ELLIOTT C. H.
Published: August 2006

We studied House Finch Carpodacus mexicanus roosting behaviour during the non‐breeding season using radiotracking and direct observations in Ithaca, NY, USA. In contrast to what has been reported in the literature and in contrast to what should be expected from Newton's European studies of cardueline finches, House Finches roost in small groups (mean 3.5; maximum 11) and do not display at roost sites. Seventy‐seven per cent of the birds re‐used the same tree on successive observations. In winter, birds re‐used the same roost tree more often than in the autumn, and birds with mycoplasmal conjunctivitis tended to move more between roost trees than did birds without conjunctivitis. A small number of radiotagged birds that roosted in the same tree were observed together in the daytime more often than by chance, suggesting the existence of social bonds between birds (some same sex) during the non‐breeding season. In the autumn the birds often roosted in leafed deciduous trees and closer to their daytime feeding locations than they did in winter. In winter all birds roosted in evergreen trees. It is possible that the reliable and predictable food sources at feeding sites offered by the public might have changed House Finch roosting behaviour.
Acute haemodynamic effects of erythropoietin alone and in combination with dopamine in a porcine model
Authors: Kristensen Jens , Soegaard Henrik , Maeng Michael , Rehling Michael , Nielsen Torsten Toftegaard
Published: August 2006

Background:  Previous studies in rodents from different kinds of shock models and isolated vessel models indicate that erythropoietin (EPO) has haemodynamic effects through interaction with sympathetic stimuli. This has relevance to the recently described non‐haematopoietic effects of EPO, e.g. tissue protective effects. Studies describing the acute effects on integrated physiological haemodynamic variables in larger animal models are scarce though.

Aim:  To examine the acute effects of EPO on standard physiological haemodynamic parameters as well as a possible synergistic effect of a sympathetic agonist (dopamine) and EPO on these parameters.

Results and design:  A porcine model was applied. Invasive haemodynamic variables were recorded at baseline, during 2 h after EPO injection and with addition of dopamine. Significant changes were only seen with addition of dopamine. Thus cardiac output increased only significantly in control group (21% versus 4%, P<0·05), and accordingly a decline in systemic vascular resistance was only seen in the control group (19% versus 5%, P< 0·05) with addition of dopamine. Pulmonary vascular resistance increased in EPO group (42% versus unchanged, P<0·05). There was a trend towards increase in left ventricular contractility as measured by slope of the pressure–volume relation (Emax) in EPO group with addition of dopamine.

Conclusion:  Erythropoietin has small but significant haemodynamic effects on the response to a sympathetic agonist in the present minimal invasive porcine model.
The Role of OR in Information Systems Strategy Development
Authors: Ormerod R.J.
Published: August 2006

Some of the most inspiring OR successes in World War II addressed the deployment of new technology into military operations. Today information technology has strategic implications for most if not all organisations. In addition to their structuring and analytical expertise, OR practitioners have developed skills of intervention, knowledge of how organisations work and experience of implementing change. OR should therefore have much to contribute to information systems strategy development and implementation but there is little evidence of activity in the U.K. at least. The paper considers why this might be the case and challenges the OR community to get involved before it is too late. This lack of activity in the U.K. is particularly surprising given the development of an interest in ‘soft’ OR methods, which are well suited to the development of information systems strategy. As an example, the contribution of ‘soft’ OR methods to the development of an IS strategy for a large retailing chain is described.
Simulation Exercise on Time Perception Parameters in Discrete‐time Dynamic Assignment Models
Authors: Bellei G. , Bielli M. , Gastaldi M.
Published: August 2006

In order to assess the performance of information systems to road users and of demand management measures, like staggered and/or flexible work times and road pricing, with respect to congestion prevention problems, it is necessary to simulate dynamics of traffic flows on the transport network and users' behaviour. This can be accomplished by taking into account several aspects such as users' information level, travel demand distribution over time and the expected smoothing effect of adopted measures and information systems. Dynamic assignment and arrival time choice models and computational procedures to perform this assessment for various traffic scenarios and hypotheses about users' behaviour are presented in this paper. Moreover, the indicators needed to quantify information systems and demand management effectiveness are identified together with parameters defining traffic scenarios. The main results obtained by applying these models and techniques as deterministic and probabilistic simulation tools are also presented and discussed.
Optimizing Frequencies in a Transit Network: a Nonlinear Bi‐level Programming Approach
Authors: Constantin I. , Florian M.
Published: August 2006

We consider the problem of optimizing the frequencies of transit lines in an urban transportation network. The problem is formulated first as a nonlinear nonconvex mixed integer programming problem and then it is converted into a bi‐level Min–Min nonconvex optimization problem. This problem is solved by a projected (sub)gradient algorithm, where a (sub)gradient is obtained at each iteration by solving the lower level problem. Computational results obtained with this algorithm are presented for the transit networks of the cities of Stockholm, Sweden, Winnipeg, Man., Canada and Portland, OR, U.S.A.
Lot Size Scheduling using Fuzzy Numbers
Authors: Pappis C.P. , Karacapilidis N.I.
Published: August 2006

Due to imprecision that is often inherent in the estimates of future demand for various products in a batch type production system, there are cases where the lot sizing problem may be more naturally treated using fuzzy concepts. Triangular fuzzy sets may be employed in order to represent qualitative estimates that are expressed linguisticaly. In this paper the above approach is introduced in order to derive an appropriate number of production runs and the corresponding lot sizes.
Guided Neural Network Learning Using a Fuzzy Controller, with Applications to Textile Spinning
Authors: Wu P. , Fang S‐C. , Nuttle H.L.W. , Wilson J.R. , King R.E.
Published: August 2006

We apply neural networks to build a metamodel of the relation between key input parameters and output performance measures of a simulated textile spinning plant. We investigate two different neural network estimation algorithms, namely back‐propagation and an algorithm incorporating a fuzzy controller for the learning rate. According to our experience, both algorithms are capable of providing high‐quality predictions. In addition, results obtained using a fuzzy controller for the learning rate suggest a significant potential for speeding up the training process.
Influence of the Limited Service Capacity of the Inspection Station on the Control Policy of an Automatized Production System
Authors: Braglia M.
Published: August 2006

The influence of the limited capacity of an inspection station on the control policy is studied for a job shop manufacturing process. The production system and the control station are described by queue models M/G/1 and G/G/1, respectively. The deterministic sampling rate is obtained which, in case of breakdown, minimizes the number of defective units.
Dynamic Location and Entry Mode Selection of Multinational Manufacturing Facilities under Uncertainty: A Chance‐constrained Goal Programming Approach
Authors: Min H. , Melachrinoudis E.
Published: August 2006

As the global marketplace continues to expand, the firm's location strategy should shift from domestic to international. An international location problem is different from the traditional domestic location problem in that the former is influenced by a greater variety of uncontrollable, unpredictable, and dynamic factors than is the latter. These factors may include political conditions, expropriation risks, trade regulations, currency exchange rates, cultural differences, and global distribution channel structures. Consequently, the international location problem is more diverse, volatile and complex. Nevertheless, a vast majority of the location literature overlooked many important international aspects. To help the multinational firm formulate viable location strategies in the changing world marketplace, this paper proposes multiple‐period, multiple‐plant, multiple‐objective, and stochastic location model.
Effective Engineering Design through Simulation
Authors: Sanchez S.M. , Sanchez P.J. , Ramberg J.S. , Moeeni F.
Published: August 2006

This paper presents a framework for designing, analyzing and improving systems and processes via discrete event simulation. The framework incorporates a robust design philosophy into a response surface metamodeling approach, and the simulation setting provides the analyst with an increased level of control relative to industrial experimentation. System optimization and improvement efforts can be carried out efficiently and effectively, providing insights into system behavior and suggesting optimal system configurations which may yield substantial improvements over those selected using more traditional approaches. One noteworthy benefit of the simulation framework is that robust design methodologies can be applied prospectively – at the inception and conceptualization phases of an engineering design project. We illustrate the method by considering the design of a small job shop.
Optimizing Long‐term Hydro‐power Production Using Markov Decision Processes
Authors: Lamond B.F. , Boukhtouta A.
Published: August 2006

Modelling the long‐term operation of hydroelectric systems is one of the classic applications of Markov decision process (MDP). The computation of optimal policies, for MDP models, is usually done by dynamic programming (DP) on a discretized state space. A major difficulty arises when optimizing multi‐reservoir systems, because the computational complexity of DP increases exponentially with the number of sites. This so‐called ‘curse of dimensionality’ has so far restricted the applicability of DP to very small systems (2 or 3 sites). Practitioners have thus had to resort to other methodologies for the long‐term planning, often at the expense of rigour, and without reliable error estimates. This paper surveys recent research of MDP computation, with application to hydro‐power systems. Three main approaches are discussed: (i) discrete DP, (ii) numerical approximation of the expected future reward function, and (iii) analytic solution of the DP recursion.
On the Use of a Mixed Integer Non‐linear Programming Model for Refrigerant Design
Authors: Churi N. , Achenie L.E.K.
Published: August 2006

In this paper, a novel mixed integer non‐linear programming model for single component refrigerant design is presented. At the heart of the approach is a new formulation for structural feasibility that allows multiple bonds, connectivity and isomers. The strategy defines a set of structural groups (consisting of atoms), subsets of which are combined to form refrigerant molecules. Molecules formed this way must obey structural and stability constraints. The design objective is to build a refrigerant molecule that has desired physical properties and performance characteristics. These attributes are formulated as mathematical programming constraints and performance objectives which involve both continuous and integer variables. With the current renewed interest in the environment, the suggested approach is applied to refrigerant design with an environmental constraint. The results indicate the viability and the flexibility of the approach.
Design Verification for Bent Sheet Metal Parts: A Graphs Approach
Authors: Duflou J.R.
Published: August 2006

Design for manufacturing requires the flexible verification and optimization of design features with regard to the suitability to the planned production methods. The automatic identification and generation of a suitable process plan for large scale bent sheet metal parts would provide a tool that would allow efficient feedback in the design phase. In this paper, a number of problem‐size reduction methods are proposed to bring automatic manufacturability verification a few steps closer to reality. The scale of the reformulated combinatorial problems is illustrated, indicating the suitability for solution by means of known search algorithms.
Topological Design of Centralized Computer Networks
Authors: Pirkul H. , Gupta R.
Published: August 2006

Topological design of centralized computer‐communication networks is an important issue that has been investigated by a large number of researchers. Such networks typically involve a large number of terminals connected by low or medium speed lines to concentrators, which are then connected to a central computing site by high speed lines. This problem is known to be a very difficult one. In general, the design problem involves determining the following: (a) the numbers and locations of concentrators that are to be opened; (b) the topology of connecting user nodes to concentrations sites; and (c) determining the links between open concentrators and the central node. Since the overall design problem belongs to the class of problems that are NP Hard, most prior research has investigated ways in which to disaggregate the problem into several simpler problems that can be solved iteratively until a satisfactory solution is reached. The problem we solve is this research involves multipoint lines between terminals and concentrators, and dedicated lines between concentrators and the central node. This problem therefore combines features of concentrator location problems as well as local access network design problems. We utilize a Lagrangian heuristic designed to efficiently solve this problem with gap ranging from 2.7 to 10.4% of the lower bound.
Adaptive Queueing: A Study Using Dynamic Structure DEVS
Authors: Barros F.J. , Zeigler B.P.
Published: August 2006

Conventional modeling methodologies only give support for the representation of model behavior, providing no help for describing changes in model structure. Some models are better represented by changes in their structure. Instead of forcing these changes to be represented at the simple behavioral level, a strong theoretical support is needed to allow the representation of structural changes in a natural way. In this paper we present a new modeling methodology for representing Dynamic Structure Systems. To illustrate this methodology we describe a dynamic structure queueing system. This system dynamically changes its structure to improve performance.
Wanted: Dead OR Alive—Ways of Using Problem‐structuring Methods in Community OR
Authors: Taket A. , White L.
Published: August 2006

Problem structuring has often been seen as providing an appropriate framework for Community OR; from our point of view the question to raise is not how to choose the best method for any particular situation, but how to act on opportunities to use different methods in practice, i.e. making the process the central focus. In this paper we examine our use of problem‐structuring methods in the context provided by postmodernist poststructuralist ideas in some Community OR (COR) case studies. In particular this paper will:

• scrutinise the notion of ‘problem’ and suggest that it might open a larger space for action and choice to recast this in terms of issues;

• show the applicability of issue‐structuring methods in combination with other participatory methods, e.g. rapid appraisal and action methods, especially in the context of evaluation, which most of our case studies will be concerned with;

• illustrate the possibilities of mixing and matching different parts of different issue structuring methods in practice.

In this way we demonstrate some ways in which the practice of OR can be revitalised, in particular through a re‐conceptualisation of the notion of ‘praxis’.
On the Application of an Economic Life Model with a Fixed Planning Horizon
Authors: Scarf P.A. , Hashem M.H.
Published: August 2006

Capital replacement models with finite planning horizons may be used to model replacement policies in complex operational contexts. They may also be used to investigate the cost consequences of technological change. These models are refinements of earlier economic life models, and this paper describes the application of one such model, with a fixed planning horizon, to the management of replacement for a large inhomogeneous fleet of buses. The paper also describes the behaviour of a simple fixed planning horizon model in a general context.
Logarithmic Barrier Decomposition Methods for Semi‐infinite Programming
Authors: Kaliski J. , Haglin D. , Roos C. , Terlaky T.
Published: August 2006

A computational study of some logarithmic barrier decomposition algorithms for semi‐infinite programming is presented in this paper. The conceptual algorithm is a straightforward adaptation of the logarithmic barrier cutting plane algorithm which was presented recently by den Hartog et al. (Annals of Operations Research, 58, 69–98, 1995), to solve semi‐infinite programming problems. Usually decomposition (cutting plane methods) use cutting planes to improve the localization of the given problem. In this paper we propose an extension which uses linear cuts to solve large scale, difficult real world problems. This algorithm uses both static and (doubly) dynamic enumeration of the parameter space and allows for multiple cuts to be simultaneously added for larger/difficult problems. The algorithm is implemented both on sequential and parallel computers. Implementation issues and parallelization strategies are discussed and encouraging computational results are presented.
The Bin‐Packing Problem: A Problem Generator and Some Numerical Experiments with FFD Packing and MTP
Authors: Schwerin P. , Wäscher G.
Published: August 2006

In this paper a problem generator for the Bin‐Packing Problem (BPP) is presented which is suggested to be used in future for the empirical evaluation of exact and heuristic solution methods. Also some numerical experiments are performed with FFD Packing in order to identify hard problem classes of the BPP. From the results it becomes evident that the design of a previous test by Martello and Toth, in which the authors tried to verify the solution power of their method, MTP, has been biased. Thus, new experiments with MTP have been performed on instances from more challenging problem classes. Our results confirm the general opinion that MTP represents the state‐or‐the‐art for exact solution methods for the BPP, even though the size of the problems, which can be solved to a proven optimum in reasonable computing time, still appears to be unsatisfactory.
An Evolutionary Approach of Multicriteria Manufacturing Cell Formation
Authors: Pierreval H. , Plaquin M‐F.
Published: August 2006

Several approaches to designing cellular manufacturing systems exist, but they are generally based on the optimization of a single criterion, such as the minimization of the inter‐cell movement or the total cost. Unfortunately, in practice, it is often necessary to take into account multiple criteria. We present an approach based on a niched pareto evolutionary algorithm which does not rely on weights or distances to a target solution. The suggested method allows several solutions to be provided, so that a choice is offered to the decision maker, according to his/her particular constraints. A new recombination operator is also presented. This approach is illustrated on a cell formation problem using two criteria: the cell workload and the traffic between cells.
Two‐stage Maintenance of a Production System with Exponentially Distributed On‐ and Off‐periods
Authors: van Dijkhuizen G. , van Harten A.
Published: August 2006

We consider an on–off production system which is subject to failure during on‐periods. In case of a failure, the production system is maintained correctively. In addition, preventive maintenance is carried out to prevent failures. The costs of both preventive and corrective maintenance are modelled in terms of the net down‐time of the production system, that is, the time that the system is not available when needed for production. Since preventive maintenance can be planned during off‐periods, there is a perspective of significant savings if some freedom is built in concerning the starting time of preventive maintenance. Therefore, a two‐stage maintenance policy is considered, which—in a first stage—provides the maintenance manager with a finite interval during which preventive maintenance must be carried out, and—in a second stage—determines the optimal starting time for preventive maintenance within this interval. Computational results offer useful insights, and indicate that significant savings can be achieved in comparison with a classical age maintenance policy.
Modelling the Retail Sales of Gasoline in a Portuguese Metropolitan Area
Authors: Themido I.H. , Quintino A. , Leitão J.
Published: August 2006

This paper describes the modelling approach for the sales of gasoline in service stations located in a Portuguese metropolitan area. The models were developed for planning purposes in order to assess potential sales of new sites. The estimates produced are more accurate than those made by previous models and are currently being used to support investment decisions of the largest Portuguese company. Starting from a basic multiplicative regression model, several segmentations of the service stations were obtained. Among these, the submodels for service stations located in urban areas and for service stations located along routes produced a better fit. The models reflect, without exception, the importance of the variables representing the size of service station and the “traffic” passing by, as well as variables which express location and road type. The fast growth experienced by this market explains the lesser impact on sales of the area sales potential and of competition.