bluuebunny/crossref_metadata_2025 huggingface dataset:
The impact of reading a web site's privacy statement on perceived control over privacy and perceived trust
Authors: Arcand Manon , Nantel Jacques , Arles‐Dufour Mathieu , Vincent Anne
Published: October 2007

Purpose

The purpose of this research is to study the impact of reading a web site's privacy statement on the perceptions of control over privacy and trust in a cyber merchant.

Design/methodology/approach

Two experiments were designed to monitor the actual reading of the privacy statement. Study one compares the influence of actual reading with self‐reported claims. Study two manipulated the format of the privacy statement (opt‐in or opt‐out) and included a control condition to assess the influence of the presence of a privacy statement and the influence of the format on the dependent variables.

Findings

The findings show that the mere presence of a privacy statement has a positive influence on perceived control. However, reading the privacy statement does not necessarily have a positive influence on perceived control and trust, contrary to commonly held assumptions. Participants who read the opt‐in format felt significantly more control and trust than the participants who read the opt‐out format. The opt‐out format decreases perceived control compared with the group that did not read the privacy statement when it was available.

Research limitations/implications

The sample size for both experiments was relatively modest, which limits the generalisability of the findings.

Practical implications

Cyber merchants should devote particular attention to the strategic role of the format of the privacy statement.

Originality/value

In contrast to other studies that relied on surveys, this paper assesses the impact of the actual reading of the privacy statement via an experimental approach. Moreover, the impact of the format of the privacy statement has been empirically tested.
Protecting online information sharing in peer‐to‐peer (P2P) networks
Authors: Rice Daniel O.
Published: October 2007

Purpose

The purpose of this paper is to present a P2P network security pricing model that promotes more secure online information sharing in P2P networks through the creation of networks with increased resistance to malicious code propagation. Online information sharing is at an all‐time high partly due to the recent growth in, and use of, online peer‐to‐peer (P2P) networks.

Design/methodology/approach

The model integrates current research findings in incentive compatible network pricing with recent developments in complex network theory. File download prices in P2P networks are linked to network security using a graph theory measurement called the Pearson coefficient. The Pearson coefficient indicates a structural dimension of scale‐free networks (scale‐free networks like the internet) called preferential attachment. Preferential attachment refers to the network property where the probability for a node to connect to a new node is greater if the new node already has a high number of connections.

Findings

The P2P network security pricing model concept is illustrated to show how the model functions to create more secure P2P networks.

Research limitations/implications

Future research in P2P network security pricing should focus on testing the model presented in this paper by numerical experiments and simulation including the tracking of malicious code propagation on networks grown under the pricing model.

Originality/value

The P2P network security pricing model demonstrated here is a different approach to network security that has a strong potential to impact on the future security of P2P and other computer based networks.
The dimensions of cited reference enhanced database subsets
Authors: Jacsó Péter
Published: October 2007

Purpose

The purpose of this paper is to discuss databases with cited references.

Design/methodology/approach

The paper considers the dimensions of cited reference enhanced database subsets.

Findings

The typical database has the ski slope shape, as there is a fairly steady, gradual growth in the yearly number of records added. This is not true for the shape of the cited references subset, as in most databases cited references have been added to the records only for the past few years.

Practical implications

There are many features which are specific to cited references, and thus the traditional bibliographic database design is just not sufficient.

Originality/value

The paper examines the issues surrounding cited reference enhanced database subsets.
The manufacturing extraprise: an emerging production network paradigm
Authors: Karlsson Christer , Sköld Martin
Published: October 2007

Purpose

Traditional perspectives of manufacturing strategy tend to focus internal transforming activities, including how transformed resources are handled and the relations with other value‐creating operations inside and outside the firm. Manufacturing management evolved as a discipline with little clear alignments with business strategy and firm positioning. Even manufacturing strategy is often delimited to the boundaries of the firm and its dyad relations to collaborating actors such as suppliers and distributors. This paper aims at exploring and demonstrating what a network perspective can add to the understanding of manufacturing management and strategy.

Design/methodology/approach

The research design is built on principal reasoning of future manufacturing strategy. Articles and conference papers together with over 25 years of field studies constitute the empirical base. An industry was chosen to demonstrate the application of the research framework of horizontal and vertical technologies.

Findings

The analysis indicates that manufacturing occurs within open‐production systems here called extraprises as an extension to enterprises with their inside the firm focus. Taking a network perspective, it is suggested that a conceptual framework of horizontal and vertical technologies offers a fruitful conceptualization to identify the content and meaning of future manufacturing strategy.

Research implications/implications

The network theory conceptualization takes the view of manufacturing systems a further step beyond systems theory and contributes a richer framework for manufacturing strategy research.

Originality/value

It is argued that future directions of manufacturing strategy will gain from taking a network perspective using network theory with its foundations in actors, resources, and activities.
The evolution of production systems and conceptual frameworks
Authors: Fleury Afonso , Tereza Fleury Maria
Published: October 2007

Purpose

The development of a conceptual framework for the study of production systems in general derived from the analysis of the telecommunications industry; since this industry is considered as one of the pillars of the coming information society and knowledge economy, the application of that framework to other industries and production systems brings insights as to their recent changes and future trends. This paper looks at the stream of frameworks proposed for production and operations management, with the intent of contributing to the debate by addressing the following question: would an analytical framework derived from the telecommunications industry have distinct features relative to the analytic frameworks currently in use?

Design/methodology/approach

Following a literature review of the evolution of the telecommunications industry, the framework (TbF for telecommunications‐based framework) was built from scratch, using grounded theory, case studies and Delphi methods. The field for research was the Brazilian Telecommunications industry, considered as a microcosm of the whole industry. The TbF was then applied to the automobile and textile/apparel industries for illustration purposes.

Findings

The TbF is composed by six types of companies, characterised by distinct profiles of organisational competences, interacting according to some specific patterns of relationships. Compared to the most commonly used conceptual frameworks, the TbF allows for critical assessments in regards to their basic assumptions and reveals ways to evolve in direction of more dynamic approaches to the study of production systems.

Research limitations/implications

As all other conceptual frameworks, the TbF is a simplification of reality and so its use requires a clear view of its assumptions. In regards to generalisation, the main assumption of the TbF is that other industries and production systems are accelerating their “clockspeeds” over time. As to the TbF's limitations, the main drawback relates to its development being derived from the most “traditional” segment of the telecommunications industry. This led to the exclusion of the internet‐enabled industries which promise a great impact in the near future.

Practical implications

The main contribution is for practical work in the academic and consultancy spheres, because what is under investigation is the way in which knowledge about production systems is being produced. The use of the TbF might disclose the limitations of the most commonly used conceptual frameworks and reveal ways to produce knowledge which is more aligned to the dynamism and complexity of production systems now and in the future.

Originality/value

The TbF is original in its structure. Its value in the creation of knowledge which is relevant and applicable still depends on further development.
Strategic options‐based framework for management of dynamic capabilities in manufacturing firms
Authors: Kyläheiko Kalevi , Sandström Jaana
Published: October 2007

Purpose

The purpose of this paper is to launch a dynamic strategic framework for a manufacturing firm for the digital age. The paper's dynamic capabilities‐ and strategic options‐based framework is comprised of the following key issues: how to sense the weak signals at the customer interface and how to formulate them as strategic options; how to exercise these options in the (often) intangible assets markets that are imperfect or even non‐existent; how to appropriate and/or share strategically relevant productive knowledge in order to obtain competitive advantage (CA) over the rivals, (iv) how to recognize the opportunities and threats of the underlying industrial structure, especially the economies of scale and scope and network externalities; and how to proactively reconfigure and reshape the existing knowledge base and capabilities in order to sustain the CA obtained.

Design/methodology/approach

The paradigm of creating CA is opened up in the context of knowledge‐based engineering and digital manufacturing. The Porterian five forces model, the resource‐based view and especially its dynamized extension, the dynamic capability view, are used as theoretical starting points. The modern strategic technology management literature will be complemented by means of the concepts of strategic options and related flexibility issues. Some illustrative examples will be offered as well.

Findings

In the author's view, the primary sources of sustainable CA in the digital manufacturing can be captured from active asset selection (strategic investments in both tangible and intangible assets), and efficient orchestrating of the global value net in “thin” intangible assets markets. The main determinants of CA are: the competitive nature of external environments, supply and demand conditions of the industry (economies of scale and scope and network externalities), renewal capacity of the organization, the dependence on complementary co‐specialized resources and capabilities, and the strategic role of the appropriability regime.

Originality/value

This paper tries to capture the critical elements of creating sustainable CA in the context of digital manufacturing and it is considered to be useful for strategic decision‐makers. The modern technology strategy management literature is synthesized in our framework and it tries to make the issues more applicable to the strategic management of the companies.
The impact of the demographic transition on manufacturing
Authors: Thun Jörn‐Henrik , Größler Andreas , Miczka Switbert
Published: October 2007

Purpose

The purpose of the paper is twofold: to discuss characteristics and potential effects of an ageing workforce and to present the perception manufacturing managers have of the influence of demographic change on the manufacturing function.

Design/methodology/approach

The phenomenon of demographic change and the characteristics of ageing workers are presented based on a literature study. In addition, the results of a survey within German industrial firms are put forward, in which operations managers were asked about their perception of older workers in manufacturing.

Findings

Effects of the demographic transition will influence manufacturing companies in every economy. An ageing workforce is well suited to support quality‐focussed manufacturing strategies. Yet, the adoption of new manufacturing technologies might be hampered by the older employees' unwillingness to learn that is assumed commonly.

Research limitations/implications

The empirical research provides a first look at the substantial impact that demographic change will have on manufacturing companies. The discussion is based on trends in Germany and on the reported perceptions of German manufacturing managers; however, it is argued that implications can be transferred to other economies.

Practical implications

Practitioners will see the necessity to consider the impact of demographical change in future decisions. It is discussed which commonly held beliefs about older workers are justified based on scientific research.

Originality/value

Focusing on the demographic transition, this paper adds an important aspect to the academic discussion of the future of manufacturing, highlighting the significant consequences that demographic change will have on manufacturing and suggesting concepts for addressing the challenge in practice. Furthermore, it provides first empirical results of the perception of manufacturing directors about this topic.
Is China's manufacturing sector becoming more high‐tech?
Authors: Vaidya Kirit , Bennett David , Liu Xiaming
Published: October 2007

Purpose

The paper assesses the extent to which China's comparative advantage in manufacturing has shifted towards higher‐tech sectors between 1987 and 2005 and proposes possible explanations for the shift.

Design/methodology/approach

Revealed comparative advantage (RCA) indices for 27 product groups, representing high‐, medium and low‐tech sectors have been calculated. Examination of international market attractiveness complements the RCA analysis. Findings for selected sectors are evaluated in the context of other evidence.

Findings

While China maintains its competitiveness in low‐tech labour intensive products, it has gained RCA in selected medium‐tech sectors (e.g. office machines and electric machinery) and the high‐tech telecommunications and automatic data processing equipment sectors. Evidence from firm and sector specific studies suggests that improved comparative advantage in medium and high‐tech sectors is based on capabilities developing through combining international technology transfer and learning.

Research limitations/implications

The quantitative analysis does not explain the shifts in comparative advantage, though the paper suggests possible explanations. Further research at firm and sector levels is required to understand the underlying capability development of Chinese enterprises and the relative competitiveness of Chinese and foreign invested enterprises.

Practical implications

Western companies should take account of capability development in China in forming their international manufacturing strategies. The rapid shifts in China's comparative advantage have lessons for other industrialising countries.

Originality/value

While RCA is a well‐known methodology, its application at the disaggregated product group level combined with market attractiveness assessment is distinctive. The paper provides a broad assessment of changes in Chinese manufacturing as a basis for further research on capability development at firm and sector levels.
Post mass production paradigm (PMPP) trajectories
Authors: Kuehnle Hermann
Published: October 2007

Purpose

The paper intends to contribute to interpretations of present and future developments in manufacturing and manufacturing research. It designs hypothetical expert consolidated projections for the future of manufacturing with the focus on social impacts from information and communications technologies (ICT).

Design/methodology/approach

In order to obtain valid projections, Kuhn's theory of scientific revolutions has been applied to production sciences. Since, the paradigm shift to post mass production has become evident, it is clear that manufacturing will be of network type. Since, the point of a “normal science” (Kuhn) is not yet reached, empirical and methodical work is exploited, especially expert discussion results, technology forecasts and field surveys, to draw the baselines for further developments, focussing on development lines on global, regional as well as company scale.

Findings

The paper sketches organisational set ups and ICT applications for future manufacturing in order to be able to point out induced effects on other trends and drivers (especially social and societal). Major changes in role and future behaviour of manufacturing could be verified.

Research limitations/implications

The paper assumes a specific driver/impact constellation, which emphasises socio‐technical relations and focuses on organisation and ICT use in manufacturing environments as decisive and limiting influences. Other socio/technology interrelations are not regarded as intensively and could be future research fields. Implications on the methods and the instruments to be used for production networks could be sketched.

Practical implications

Some of the methodologies may be downscaled and applied for companies in order to define future strategies. On global, on regional as well as on company level, relevant results may be considered as elements of a future networked manufacturing world.

Originality/value

Trends and drivers for future manufacturing have been newly put into network interrelations in order to obtain impact priorities and interaction hypotheses. Ongoing developments are envisioned as embedded in a general paradigm change. The paper draws from extensive research work on the field. It addresses researchers as well as practitioners dealing with manufacturing companies' strategy development.
The Keys of the Kingdom
Authors: Childe Wilfred
Published: October 2007

The swarming patriarchs of the Orient Assembling thus debated, how the Son Took on Him human flesh, and how the One Could yet be Three in One, Three still unblent; Turmoiled with multitudinous argument,

Rich Asia panted and the Nile’s domain Wrestled with falsehood in her subtle brain, Golden Byzantium blazed pre-eminent:

Yet all this while over the heaving sea Of definition and perplexity,

Bringing forth truth from out the dark abyss, The white Dove brooded with sustaining wings, And throned on ruins of Rome’s majesties, Peter in face of loud barbarian kings ....

Wilfred Childe.
Al Smith's Noble Reply
Authors: Jarrett Bede
Published: October 2007

We feel sure that readers of Blackfriars will welcome a resume of the open correspondence between Mr. Charles C. Marshall and Mr. A. E. Smith. It will be forever memorable in the history of English-speaking Catholicism. Mr. Marshall is an eminent Episcopalian lawyer; Mr. Alfred E. Smith, the popular Governor of the New York State, is almost certain to be the next democratic candidate for the American Presidency, and would undoubtedly have been so at the last nominations, were he not a Catholic and therefore a victim of sectarian prejudice. This prejudice, whatever be his disclaimers, must unconsciously have moved Mr. Marshall to publish his ‘Open Letter to the Honourable Alfred E. Smith’ in the April number of The Atlantic Monthly (pp. 540-549).

The general drift of his letter is shown clearly enough in the opening and concluding paragraphs; the Governor’s reply sufficiently explains the rest of the attack.

Sir,—The American people take pride in viewing the progress of an American citizen from the humble estate in which his life began toward the highest office within the gift of the nation. It is for this reason that your candidacy for the Presidential nomination has stirred the enthusiasm of a great body of your fellow citizens. They know and rejoice in the hardship and the struggle which have fashioned you as a leader of men. They know your fidelity to the morality you have advocated in public and private life and to the religion you have revered; your great record of public trusts successfully and honestly discharged; your spirit of fair play, and justice even to your political opponents.
Human cholesterol metabolism and therapeutic molecules
Authors: Charlton‐Menys V. , Durrington P. N.
Published: October 2007

There has been a fascinating interplay between the discovery of some of the key enzymes, receptors and transporters in cholesterol biosynthesis and transfer and the development of drugs for the regulation of cholesterol metabolism. The discovery of the low‐density lipoprotein (LDL) receptor led to the realization that circulating LDL cholesterol could be decreased when hepatic LDL receptor expression was stimulated by decreasing intrahepatic cholesterol levels. The first class of drugs which operate in this way were the bile‐acid sequestrating agents, which, by interrupting the enterohepatic circulation of bile acids, deplete the liver of cholesterol used to replenish the pool of bile salts. Ezetimibe, which was developed to block cholesterol absorption from the intestine, led to the discovery of the Nieman‐Pick C1‐Like 1 sterol transporter channel. The statins, which have proved enormously successful in preventing cardiovascular disease, were discovered amongst fungal metabolites which inhibit hydroxyl methyl CoA reductase, the rate‐limiting enzyme for hepatic cholesterol biosynthesis. Drugs which block enzymes at other stages of the cholesterol biosynthetic pathway, particularly the squalene synthase inhibitors, are entering the clinical phase of their development. Drugs which interfere with hepatic very low‐density lipoprotein assembly in the liver, such as microsomal triglyceride transfer protein inhibitors and apolipoprotein B mRNA antisense oligonucleotides, are currently undergoing evaluation. Cholesteryl ester transfer protein (CETP) inhibitors, which decrease cholesteryl ester heteroexchange within the circulation, have undergone development to the point of clinical evaluation, and this will eventually settle the controversy about whether CETP is pro‐ or antiatherogenic.
Genes, endothelial function and cerebral small vessel disease in man
Authors: Markus Hugh S.
Published: October 2007

Cerebral small vessel disease results from ischaemia in the perforating arteries supplying the white matter and deep grey matter nuclei. It results in both focal lacunar infarction and more diffuse areas of chronic ischaemia (leukoaraiosis). Two subtypes may exist. One subtype (isolated lacunar infarction) is associated with single or a few larger lacunar infarcts without leukoaraiosis, and may result from microatheroma in the larger perforating arteries. The second subtype (ischaemic leukoaraiosis) results in multiple small lacunar infarcts with leukoaraiosis secondary to a diffuse arteriopathy affecting the smaller perforating arteries, usually occurring in the presence of hypertension. In this subtype, chronic hypoperfusion and impaired cerebral autoregulation have been reported. A number of lines of evidence support a pathogenic role of endothelial activation and dysfunction. Genetic predisposition has also been implicated. Associations with genes involved in endothelial function, including those regulating the renin–angiotensin system, endothelial nitric oxide and homocysteine levels, have been reported. However, not all results have been replicated and there are few robust replicable associations. Larger studies are required to determine definitively which associations represent important risk factors.
Interactions between maternal subtotal nephrectomy and salt: effects on renal function and the composition of plasma in the late gestation sheep fetus
Authors: Boyce Amanda C. , Gibson Karen J. , Thomson Clare L. , Lumbers Eugenie R.
Published: October 2007

Effects of altered maternal salt intake between 122 and 127 days gestation (term is 150 days) were studied in eight fetuses carried by ewes which had renal insufficiency caused by subtotal nephrectomy (STNxF) and seven fetuses carried by intact ewes (IntF). Plasma sodium and osmolality were increased in ewes with subtotal nephrectomy on a high‐salt intake (0.17 m NaCl in place of drinking water for 5 days; P < 0.05). The STNxF had normal body weights. A high maternal salt intake did not affect fetal blood pressure or heart rate. Plasma osmolality was higher in STNxF (P < 0.001), and plasma sodium and osmolality were increased by high salt (P < 0.001 and P < 0.04, respectively). The STNxF had higher urinary osmolalities (P= 0.002), which were also increased by a high maternal salt intake (P= 0.03). Renal blood flow fell in STNxF in response to a high maternal salt intake, but increased in IntF (P= 0.003). In STNxF but not IntF, glomerular filtration rate and urinary protein excretion were positively related to fetal plasma renin levels (P≤ 0.01). It is concluded that the salt intake of pregnant ewes with renal insufficiency affects maternal and fetal osmolar balance, fetal plasma sodium and fetal renal function. Since STNxF also had altered renal haemodynamic responses to high maternal salt and evidence of renin‐dependent glomerular filtration and protein excretion, we suggest that interactions between dietary salt and pre‐existing maternal renal disease impair glomerular integrity and function in the fetus.
Insulin resistance and endothelial cell dysfunction: studies in mammalian models
Authors: Kearney Mark T. , Duncan Edward R. , Kahn Mathew , Wheatcroft Stephen B.
Published: October 2007

Type 2 diabetes and obesity are major risk factors for the development of cardiovascular atherosclerosis. Resistance to the metabolic effects of insulin on its traditional target tissues (muscle, liver and adipose tissue) is a central pathogenic feature of these disorders. However, the role of insulin resistance in non‐canonical tissues, such as the endothelium, is less clear. Several large studies support a role for insulin resistance in the development of premature cardiovascular atherosclerosis independent of type 2 diabetes and obesity. A key step in the initiation and progression of atherosclerosis is a reduction in the bioactivity of endothelial cell‐derived nitric oxide. Nitric oxide is a signalling molecule which has a portfolio of potential antiatherosclerotic effects. The presence of insulin receptors on endothelial cells is well documented, and the endothelium has now emerged as a potentially important target tissue for insulin, with insulin‐stimulated production of nitric oxide a feature of the action of insulin on endothelial cells. The role of insulin resistance at the level of the endothelial cell in vascular pathophysiology is unclear. A number of studies in humans and gene‐modified mice have demonstrated a close association between insulin resistance and nitric oxide bioactivity. In this review, we discuss the link between insulin resistance and endothelial cell function in humans and demonstrate the complimentary information provided by murine models of obesity and insulin resistance in our understanding of the vasculopathy associated with type 2 diabetes and obesity.
The pulmonary vascular response to the sustained activation of the muscle metaboreflex in man
Authors: Lykidis Christos K. , White Michael J. , Balanos George M.
Published: October 2007

The pulmonary circulation is influenced by the autonomic nervous system, yet whether this is physiologically important during exercise in man is not known. The aim of this study was to assess the pulmonary vascular response to sympathoexcitation induced by the maintained activation of the muscle metaboreflex in the postexercise period. Nine healthy subjects performed isometric handgrip exercise at 50% of their maximal voluntary contraction force for 2 min. Exercise was followed by circulatory occlusion so as to maintain the muscle metaboreflex activated for 2 min (postexercise circulatory occlusion; PECO). Blood pressure measurements and echocardiographically determined estimates of systolic pulmonary artery pressure (SPAP) and cardiac output were obtained at various intervals throughout the two protocols. Compared with baseline values, elevations in SPAP (by 20.06 ± 2.08%), cardiac output (by 36.04 ± 4.97%) and mean arterial pressure (MAP; by 25.62 ± 3.54%) were noted during isometric exercise (means ±s.e.m., all P < 0.05). Increases in SPAP and MAP persisted during PECO (all P < 0.05), whereas cardiac output returned to resting levels. Our findings suggest that the sympathoexcitation induced by isometric exercise affects the pulmonary circulation, possibly by inducing vasoconstriction and/or stiffening the large conduit arteries. The exaggerated activation of the sympathetic nervous system that has been evidenced in cardiopulmonary patients could therefore be implicated in their abnormal pulmonary haemodynamic responses and intolerance of exercise.
Analysis of the interplay between neurochemical control of respiration and upper airway mechanics producing upper airway obstruction during sleep in humans
Authors: Longobardo G. S. , Evangelisti C. J. , Cherniack N. S.
Published: October 2007

Increased loop gain (a function of both controller gain and plant gain), which results in instability in feedback control, is of major importance in producing recurrent central apnoeas during sleep but its role in causing obstructive apnoeas is not clear. The purpose of this study was to investigate the role of loop gain in producing obstructive sleep apnoeas. Owing to the complexity of factors that may operate to produce obstruction during sleep, we used a mathematical model to sort them out. The model used was based on our previous model of neurochemical control of breathing, which included the effects of chemical stimuli and changes in alertness on respiratory pattern generator activity. To this we added a model of the upper airways that contained a narrowed section which behaved as a compressible elastic tube and was tethered during inspiration by the contraction of the upper airway dilator muscles. These muscles in the model, as in life, responded to changes in hypoxia, hypercapnia and alertness in a manner similar to the action of the chest wall muscles, opposing the compressive action caused by the negative intraluminal pressure generated during inspiration which was magnified by the Bernoulli Effect. As the velocity of inspiratory airflow increased, with sufficiently large increase in airflow velocity, obstruction occurred. Changes in breathing after sleep onset were simulated. The simulations showed that increases in controller gain caused the more rapid onset of obstructive apnoeas. Apnoea episodes were terminated by arousal. With a constant controller gain, as stiffness decreased, obstructed breaths appeared and periods of obstruction recurred longer after sleep onset before disappearing. Decreased controller gain produced, for example, by breathing oxygen eliminated the obstructive apnoeas resulting from moderate reductions in constricted segment stiffness. This became less effective as stiffness was reduced more. Contraction of the upper airway muscles with hypercapnia and hypoxia could prevent obstructed apnoeas with moderate but not with severe reductions in stiffness. Increases in controller gain, as might occur with hypoxia, converted obstructive to central apnoeas. Breathing CO2 eliminated apnoeas when the activity of the upper airway muscles was considered to change as a function of CO2 to some exponent. Low arousal thresholds and increased upper airway resistance are two factors that promoted the occurrence and persistence of obstructive sleep apnoeas.
Magnesium sulphate treatment decreases blood–brain barrier permeability during acute hypertension in pregnant rats
Authors: Euser Anna G. , Bullinger Lisa , Cipolla Marilyn J.
Published: October 2007

Eclampsia is associated with increased blood–brain barrier (BBB) permeability and formation of cerebral oedema. Magnesium sulphate is used to treat eclampsia despite an unclear mechanism of action. This study was to determine the effect of magnesium sulphate on in vivo BBB permeability and formation of cerebral oedema during acute hypertension and on brain aquaporin‐4 (AQP4) protein expression. An in vivo model of hypertensive encephalopathy was used in late‐pregnant (LP) rats following magnesium sulphate treatment, 270 mg kg−1i.p. injection every 4 h for 24 h. Permeability of the BBB was determined by in situ brain perfusion of Evan's Blue (EB) and sodium fluorescein (NaFl), and dye clearance determined by fluorescence spectrophotometry. Cerebral oedema was determined following acute hypertension by measuring brain water content. The effect of magnesium treatment on AQP4 expression was determined by Western blot analysis. Acute hypertension with autoregulatory breakthrough increased BBB permeability to EB in both brain regions studied (P < 0.05). Magnesium attenuated BBB permeability to EB during acute hypertension by 41% in the posterior cerebrum (P < 0.05) but had no effect in the anterior cerebrum (P > 0.05). Treatment with magnesium did not change NaFl permeability, cerebral oedema formation or AQP4 expression. In summary, BBB permeability to Evan's Blue was increased by acute hypertension in LP rats, and this was attenuated by treatment with magnesium sulphate. The greatest effect on BBB permeability to EB was in the posterior cerebrum, an area particularly susceptible to oedema formation during eclampsia.
Regulation of mammalian gastrin/CCK receptor (CCK2R) expressionin vitroandin vivo
Authors: Ashurst H. Louise , Varro Andrea , Dimaline Rod
Published: October 2007

The gastrin/CCK receptor (CCK2R) mediates the physiological functions of gastrin in the stomach, including stimulation of acid secretion and cellular proliferation and migration, but little is known about the factors that regulate its expression. We identified endogenous CCK2R expression in several cell lines and used luciferase promoter–reporter constructs to define the minimal promoter required for transcription in human gastric adenocarcinoma, AGS, and rat gastric mucosa, RGM1, cells. Consensus binding sites for SP1, C/EBP and GATA were essential for activity. Following serum withdrawal from RGM1 and AR42J cells, endogenous CCK2R mRNA abundance and the activity of a CCK2R promoter–reporter construct were significantly elevated. Transcription of CCK2R was also increased in AGS‐GRand RGM1 cells by gastrin through mechanisms partly dependent upon protein kinase C (PKC) and mitogen/extracellular signal‐regulated kinase (MEK). Gastrin significantly increased endogenous CCK2R expression in RGM1 cells, and CCK2R protein expression was elevated in the stomach of hypergastrinaemic animals. In mice with cryoulcers in the acid‐secreting mucosa, CCK2R expression increased progressively in the regenerating mucosa adjacent to the ulcer repair margin, evident at 6 days postinjury and maximal at 13 days.De novoexpression of CCK2R was observed in the submucosa beneath the repairing ulcer crater 6–9 days postinjury. Many of the cells in mucosa and submucosa that expressed CCK2R in response to cryoinjury were identified as myofibroblasts, since they coexpressed vimentin and smooth muscle α‐actin but not desmin. The data suggest that increased CCK2R expression might influence the outcome of epithelial inflammation or injury and that the response may be mediated in part by myofibroblasts.
Conjugate Heat Transfer Analysis of a Cooled Turbine Vane Using the V2F Turbulence Model
Authors: Luo Jiang , Razinsky Eli H.
Published: October 2007

The conjugate heat transfer methodology has been employed to predict the flow and thermal properties including the metal temperature of a NASA turbine vane at three operating conditions. The turbine vane was cooled internally by air flowing through ten round pipes. The conjugate heat transfer methodology allows a simultaneous solution of aerodynamics and heat transfer in the external hot gas and the internal cooling passages and conduction within the solid metal, eliminating the need for multiple/decoupled solutions in a typical industry design process. The model of about 3 million computational meshes includes the gas path and the internal cooling channels, comprising hexa cells, and the solid metal comprising hexa and prism cells. The predicted aerodynamic loadings were found to be in close agreement with the data for all the cases. The predicted metal temperature, external, and internal heat transfer distributions at the midspan compared well with the measurement. The differences in the heat transfer rates and metal temperature under different running conditions were also captured well. The V2F turbulence model has been compared with a low-Reynolds-number k-ε model and a nonlinear quadratic k-ε model. The V2F model is found to provide the closest agreement with the data, though it still has room for improvement in predicting the boundary layer transition and turbulent heat transfer, especially on the suction side. The overall results are quite encouraging and indicate that conjugate heat transfer simulation with proper turbulence closure has the potential to become a viable tool in turbine heat transfer analysis and cooling design.
The Effect of Wake Induced Structures on Compressor Boundary-Layers
Authors: Wheeler Andrew P. S. , Miller Robert J. , Hodson Howard P.
Published: October 2007

The interaction of a convected wake with a compressor blade boundary layer was investigated. Measurements within a single-stage compressor were made using an endoscopic PIV system, a surface mounted pressure transducer, hotfilms and hotwire traverses, along with CFD simulations. The wake/leading-edge interaction was shown to lead to the formation of a thickened laminar boundary-layer, within which turbulent spots formed close to the leading edge. The thickened boundary-layer became turbulent and propagated down the blade surface, giving rise to pressure perturbations of 7% of the inlet dynamic head in magnitude. The results indicate that wake/leading-edge interactions have a crucial role to play in the performance of compressor blades in the presence of wakes.
Assessing Convergence in Predictions of Periodic-Unsteady Flowfields
Authors: Clark J. P. , Grover E. A.
Published: October 2007

Predictions of time-resolved flowfields are now commonplace within the gas-turbine industry, and the results of such simulations are often used to make design decisions during the development of new products. Hence it is necessary for design engineers to have a robust method to determine the level of convergence in design predictions. Here we report on a method developed to determine the level of convergence in a predicted flowfield that is characterized by periodic unsteadiness. The method relies on fundamental concepts from digital signal processing including the discrete Fourier transform, cross correlation, and Parseval’s theorem. Often in predictions of vane–blade interaction in turbomachines, the period of the unsteady fluctuations is expected. In this method, the development of time-mean quantities, Fourier components (both magnitude and phase), cross correlations, and integrated signal power are tracked at locations of interest from one period to the next as the solution progresses. Each of these separate quantities yields some relative measure of convergence that is subsequently processed to form a fuzzy set. Thus the overall level of convergence in the solution is given by the intersection of these sets. Examples of the application of this technique to several predictions of unsteady flows from two separate solvers are given. These include a prediction of hot-streak migration as well as more typical cases. It is shown that the method yields a robust determination of convergence. Also, the results of the technique can guide further analysis and∕or post-processing of the flowfield. Finally, the method is useful for the detection of inherent unsteadiness in the flowfield, and as such it can be used to prevent design escapes.
Three-Dimensional Numerical Analysis of Curved Transpiration Cooled Plates and Homogenization of Their Aerothermal Properties
Authors: Laschet Gottfried , Rex Stephan , Bohn Dieter , Krewinkel Robert
Published: October 2007

Three different designs of a transpiration cooled multilayer plate—plane, convex, and concave—are analyzed numerically by application of a 3D conjugate fluid flow and heat transfer solver. The geometrical setup and the fluid flow conditions are derived from modern gas turbine components. The conjugate analysis of these designs focus on the influence of the surface curvature, the cooling film development on the plate surface, the fluid structure in the cooling channels, and on the cooling efficiency of the plate. Moreover, to predict the effective thermal properties and the permeability of these multilayer plates, a multiscale approach based on the homogenization technique is employed. This method allows the calculation of effective equivalent properties either for each layer or for the multilayer of superalloy, bondcoat, and thermal barrier coating (TBC). Permeabilities of the different designs are presented in detail for the TBC layer. The influence of the plate curvature and the blowing ratio on the effective orthotropic thermal conductivities is finally outlined.
Aerodynamic Characteristics of Supercritical Outlet Guide Vanes at Low Reynolds Number Conditions
Authors: Sonoda Toyotaka , Schreiber Heinz-Adolf
Published: October 2007

As a part of an innovative aerodynamic design concept for a single stage low pressure turbine, a high turning outlet guide vane is required to remove the swirl from the hot gas. The airfoil of the vane is a highly loaded compressor airfoil that has to operate at very low Reynolds numbers (Re∼120,000). Recently published numerical design studies and experimental analysis on alternatively designed airfoils showed that blade profiles with an extreme front loaded pressure distribution are advantageous for low Reynolds number conditions. The advantage even holds true for an increased inlet Mach number at which the peak Mach number on the airfoils reaches and exceeds the critical conditions (Mss>1.0). This paper discusses the effect of the inlet Mach number and Reynolds number on the cascade performance for both a controlled diffusion airfoil (CDA) (called baseline) and a numerically optimized front loaded airfoil. The results show that it is advantageous to design the profile with a fairly steep pressure gradient immediately at the front part in order to promote early transition or to prevent too large laminar—even shock induced—separations with the risk of a bubble burst. Profile Mach number distributions and wake traverse data are presented for design and off-design conditions. The discussion of Mach number distributions and boundary layer behavior is supported by numerical results obtained from the blade-to-blade flow solver MISES.
Effects of Bleed Rate and Endwall Location on the Aerodynamic Behavior of a Circular Hole Bleed Off-Take
Authors: Leishman B. A. , Cumpsty N. A. , Denton J. D.
Published: October 2007

In a jet engine bleed off-takes on the hub and casing endwalls, part way through the compressor, supply high-pressure air for cooling, sealing, de-icing, and aircraft cabin air applications; bleed also assists compressor operation at part-speed conditions. Two separate issues are of interest: the bleed off-take air pressure and the interaction of the bleed off-take with the primary flow through the blade passage. In this paper, the aerodynamic behavior is presented for a circular-hole bleed off-take at three endwall locations within a stationary cascade blade passage: at midpassage; near the blade pressure surface; and near the blade suction surface. Results from low-speed cascade experiments are complemented by three-dimensional numerical calculations using an unstructured mesh-based solver, in which the blade passage and bleed off-take geometry are fully modeled. The bleed off-take location and the magnitude of bleed rate influence the off-take air pressure and the interaction with the primary passage flow. For optimum design at zero and low bleed rates, off-takes near the blade pressure surface give the highest bleed air pressures and minimum loss in the blade passage. For minimum blade passage loss at higher bleed rates, however, it is necessary to take bleed near the blade suction surface. The paper discusses the causes for this pattern of behavior.
Effects of Inlet Ramp Surfaces on the Aerodynamic Behavior of Bleed Hole and Bleed Slot Off-Take Configurations
Authors: Leishman B. A. , Cumpsty N. A. , Denton J. D.
Published: October 2007

Bleed off-take air pressure and the interaction of the off-take with the primary flow through the blade passage is determined by: (1) the location of the bleed off-take at the endwall relative to the blade passage; (2) the bleed flow rate; and (3) the off-take geometry. In the companion paper (Leishman et al., 2007, ASME J. Turbomach., 129, pp. 645–658) the effect of bleed rate and endwall location was investigated using a circular hole bleed off-take configuration; the circular hole was tested at three endwall locations and for bleed flow rates between 0% and 9% of the primary (core) flow through the blade passage. The effects of bleed off-take geometry are presented in this paper by comparing the aerodynamic behavior of a number of generic bleed off-take configurations. Using results from low-speed cascade experiments and three-dimensional numerical calculations, the off-take configurations are compared with respect to the requirement to maximize bleed off-take air pressure and minimize loss generated within the blade passage. The off-take geometry, and especially the introduction of contoured inlet ramp surfaces to guide flow into the off-take for high bleed pressure, has a strong effect on its aerodynamic behavior because it determines the extent to which flow within the off-take is coupled to the primary flow through the blade passage. In this paper, the off-take configurations that give the highest bleed pressure generally cause the highest levels of loss in the blade passage.
Improved Molecular Model of a Peptide Unit for Proteins
Authors: Subramanian Raghavendran , Kazerounian Kazem
Published: October 2007

Pauling et al. (1951, “The Structure of Proteins: Two Hydrogen-Bonded Helical Configurations of the Polypeptide Chain,” Proc. Natl. Acad. Sci. U.S.A., 37(4), pp. 205–211) in their seminal paper in 1951 reported numerical values for the bond lengths and bond angles for a peptide unit in proteins. These values became the standard model for several decades after that. In this paper, we have made an attempt to calibrate the values of these bond lengths and bond angles based on a systematic approach applied to a collection of proteins defined structurally in the protein data bank (PDB). Our method is based on the assumption that a peptide chain is a serial chain of identical rigid bodies connected by revolute joints (i.e., dihedral angles). Through an optimization process, the structural error (root mean square deviation of all atoms) between the resultant conformation and the PDB data is minimized to yield the best values for the bond length and bond angles in the calibrated peptide unit. Our numerical experiments indicate that by making small changes in the Pauling-Corey peptide model parameters (0.15–8.7%), the structural error is reduced significantly (3.0–57.4%). The optimum values for the bond angles and bond lengths are as follow; bond lengths: N–C(A): 1.4721Å, C(A)–C: 1.6167Å, C–N: 1.2047Å, CO: 1.1913Å and N–H: 0.9621Å. Bond bending angles: N–C(A)–C: 109.6823deg, C(A)–CO: 119.518deg, C(A)–C–N: 114.5553deg, OC–N: 125.9233deg, C–N–H: 123.5155deg, C–N–C(A): 121.5756deg, C(A)–N–H: 114.901deg peptide bond torsion angle: ω: 179.4432deg.