bluuebunny/crossref_metadata_2025 huggingface dataset:
The Penumbra Pivotal Stroke Trial
Authors:   The Penumbra Pivotal Stroke Trial Investigators
Published: July 2009

Background and Purpose—

The purpose of this clinical evaluation was to assess the safety and effectiveness of the Penumbra System in the revascularization of patients presenting with acute ischemic stroke secondary to intracranial large vessel occlusive disease.

Methods—

In this prospective, multicenter, single-arm study, 125 patients with neurological deficits as defined by a National Institutes of Health Stroke Scale score ≥8, presented within 8 hours of symptom onset, and an angiographic occlusion (Thrombolysis In Myocardial Infarction [TIMI] Grade 0 or 1) of a treatable large intracranial vessel were enrolled. Patients who presented within 3 hours from symptom onset had to be ineligible or refractory to recombinant tissue plasminogen activator therapy. All patients were followed clinically for 90 days postprocedure.

Results—

A total of 125 target vessels in 125 patients were treated by the Penumbra System. Postprocedure, 81.6% of the treated vessels were successfully revascularized to TIMI 2 to 3. There were 18 procedural events reported in 16 patients (12.8%), 3 patients (2.4%) had events that were considered serious. A total of 35 patients (28%) were found to have intracranial hemorrhage on 24-hour CT of which 14 (11.2%) were symptomatic. All cause mortality was 32.8% at 90 days with 25% of the patients achieving a modified Rankin Scale score of ≤2.

Conclusions—

These results suggest the Penumbra System allows safe and effective revascularization in patients experiencing ischemic stroke secondary to large vessel occlusive disease who present within 8 hours from symptom onset.
Causes of Death and Predictors of 5-Year Mortality in Young Adults After First-Ever Ischemic Stroke
Authors: Putaala Jukka , Curtze Sami , Hiltunen Sini , Tolppanen Heli , Kaste Markku , Tatlisumak Turgut
Published: July 2009

Background and Purpose—

Data on mortality and its prognostic factors after an acute ischemic stroke in young adults are scarce and based on relatively small heterogeneous patient series.

Methods—

We analyzed 5-year mortality data of all consecutive patients aged 15 to 49 with first-ever ischemic stroke treated at the Department of Neurology, Helsinki University Central Hospital, from January 1994 to September 2003. We followed up the patients using data from the mortality registry of Statistics Finland. We used life table analyses for calculating mortality risks. Kaplan-Meier method allowed comparisons of survival between clinical subgroups. We used the Cox proportional hazard model for identifying predictors of mortality. Stroke severity was measured using the National Institutes of Health Stroke Scale and the Glasgow Coma Scale.

Results—

Among the 731 patients (mean age, 41.5±7.4 years; 62.8% males) followed, 78 died. Cumulative mortality risks were 2.7% (95% CI, 1.5% to 3.9%) at 1 month, 4.7% (3.1% to 6.3%) at 1 year, and 10.7% (9.9% to 11.5%) at 5 years with no gender difference. Those ≥45 years of age had lower probabilities of survival. Among the 30-day survivors (n=711), stroke caused 21%, cardioaortic and other vascular causes 36%, malignancies 12%, and infections 9% of the deaths. Malignancy, heart failure, heavy drinking, preceding infection, type 1 diabetes, increasing age, and large artery atherosclerosis causing the index stroke independently predicted 5-year mortality adjusted for age, gender, relevant risk factors, stroke severity, and etiologic subtype.

Conclusions—

Despite the overall low mortality after an ischemic stroke in young adults, several recognizable subgroups had substantially increased risk of death in the long term.
Office-Based Interventions for Recognizing Abnormal Pediatric Blood Pressures
Authors: McLaughlin Douglas , Hayes John R. , Kelleher Kelly
Published: July 2009

Interventions to improve pediatric blood pressure (BP) screening have not been well studied. The authors measured staff acceptance of 2 simple in-office interventions and measured the effect on physician recognition of elevated BP measurements. Group 1 used simplified normative pediatric BP tables affixed to the growth chart, group 2 used a personal digital assistant program (PDA) to calculate BP percentiles as part of the vital signs, and group 3 served as the control. Group detection rates by compliant (C) and noncompliant (NC) with the intervention were: (1) (BP table) C = 18%, NC = 12%; (2) (PDA) C = 33%, NC = 26%; and (3) (control) 18%. There was no statistically significant intervention effect with documented compliance ( P = .27) nor was there an effect in the noncompliant records ( P = .12). Although the interventions were used inconsistently, their presence in the medical record did not improve performance. Future education and interventions are needed to reduce barriers to elevated pediatric BP recognition.
Analysis of Deformation and Residual Stresses in Composites Processed on a Carbon Foam Tooling
Authors: Khairul Alam M. , Anghelescu Mihnea S.
Published: July 2009

Carbon foam is a low cost, durable, light-weight material with a low coefficient of thermal expansion (CTE) and it has cure process compatibility with aerospace composites. Therefore, carbon foam is being investigated as an alternative to traditional composite tooling material for aerospace applications. However, the dramatic differences in properties between traditional tooling materials and carbon foam makes it difficult to fully predict the performance of this novel material as a tooling alternative. This article is a comparative analytical study of the effects of processing of composite geometries on a carbon foam tooling vs. conventional tooling materials. Simulation is carried out on graphite-epoxy composite system using a carbon foam tooling and the stresses and the resulting deformations are predicted for three different geometric features of composites. The results show that both the lower CTE and modulus of the carbon foam tooling can contribute to a reduction of residual stresses in the part and the tooling; however, the mechanical strength of the foam needs to be considered in the tooling design.
Properties of Medium Density Fiberboard Based on Bagasse Fibers
Authors: Ashori Alireza , Nourbakhsh Amir , Karegarfard Abolfazl
Published: July 2009

In this study, sugarcane bagasse fiber was used for medium density fiberboard (MDF) manufacturing. The purpose of this study was to determine the effects of maleic anhydride (MA) and press temperature on the mechanical (static bending, modulus of elasticity, and internal bond) and physical properties (thickness swelling, water and steam absorption) of the boards. This study showed that all the MDF panels made from bagasse fibers treated with MA at 190°C press temperature had the highest values among the other types of panels for general purpose boards. In addition, treated fibers at 190°C showed minimum steam absorption. The absorption of steam increased with increase in time from 12 to 120 h in all the treatments. Beyond 120 h no additional absorption of steam was found in any of the six MDF boards. Overall results showed that MDF panels made from bagasse exceed the EN standards for internal bond, modulus of elasticity, and static bending. However, thickness swelling values were higher (poor) than requirements. For this reason, additional work needs to be done on improving the physical properties of particleboard produced from bagasse.
A Comprehensive Model for Determining Tensile Strengths of Various Unidirectional Composites
Authors: Koyanagi Jun , Hatta Hiroshi , Kotani Masaki , Kawada Hiroyuki
Published: July 2009

Simultaneous fiber-failure (SFF) model that determines tensile strengths for various systems of unidirectional composites comprehensively is presented. The SFF derives the strength of unidirectional composites as a function of the single-fiber strength distribution, interfacial shear strength, and matrix strength. The point of the SFF is that a fiber group which is considered to be experiencing simultaneous fiber failures triggered by neighboring fiber failures is assumed to fail when the weakest fiber in the fiber group fails. We discuss a method to determine the magnitude of the fiber group for various systems of composites on a basis of whether a crack located near a bi-materials interface penetrates into another material or deflects along the interface. The SFF is established by integrating the magnitude of the simultaneous fiber failures into the conventional Global load sharing model.
Analytical Modeling of Composite Molding by Resin Infusion with Flexible Tooling: VARI and RFI processes
Authors: Chung Hae Park  , Saouab Abdelghani
Published: July 2009

We present analytical modeling and closed form solutions for composite resin infusion processes such as the vacuum assisted resin infusion (VARI) process and the resin film infusion (RFI) process. As a flexible bag is placed on the top of fabric stack, while a rigid tooling is still used on the other side, a fabric deformation takes place as the resin pressure changes during the resin infiltration process. Subsequently, it is important to take into account the reinforcement compaction as well as the resin flow in the analysis of resin infusion processes. We present a fully analytical modeling of resin pressure distribution, resin flow front position, fiber volume fraction distribution, and part height change during the resin infusion process. Parametric studies are provided to investigate the influences of process parameters on the process feasibility. The evaluation of bulk permeability in the RFI process implies that the fabric compaction should be taken into account to exactly characterize the through-thickness permeability of fibrous reinforcement.
Applying the Risk Principle to Sex Offenders
Authors: Lovins Brian , Lowenkamp Christopher T. , Latessa Edward J.
Published: July 2009

The risk principle states that higher risk offenders should receive more intensive services, whereas lower risk offenders should receive less intensive services. However, the criminal justice system routinely ignores the risk principle for sex offenders and treats them all the same with little regard for level of risk. This article explores the effects of different levels of treatment intensity on 238 sexual offenders who are on parole. The findings suggest that the risk principle does, in fact, apply to sexual offenders.
Altering Category-Level Beliefs: The Impact of Level of Representation at Belief Formation and Belief Disconfirmation
Authors: Paik J. Shelly , MacDougall Bonnie L. , Fabrigar Leandre R. , Peach Jennifer M. , Jellous Kelly
Published: July 2009

This research program investigates whether representational level of information underlying initial beliefs (individual vs. category) and disconfirming information (individual vs. category) influence the magnitude of belief and attitude change regarding categories of objects. In 3 experiments, 2 key effects emerged. A main effect of type of disconfirming information indicated that category-level information produced more belief and attitude change than did individual-level information. Also, a significant interaction between type of information at formation and disconfirmation indicated a relative matching effect, with category-level disconfirmation producing substantially more belief and attitude change than individual-level disconfirmation when initial beliefs were based on category-level information but only slightly greater change when initial beliefs were based on individual-level information.
Towards a hundred issues of Critical Social Policy
Authors: Rogowski Steve
Published: July 2009

Despite the current economic crisis facing the global economy we continue to be faced with the seeming triumph of global capitalism/ neo-liberalism. This is despite the great insecurity, difficulties and hardship that undoubtedly result for the majority of people. Social workers have to deal with many of the casualties of this system on a day-to-day basis, and I argue they require journals like CSP to provide a critical perspective on social policy issues and developments at both a practical and theoretical level. This piece highlights some of the main CSP articles which have helped one social worker in this regard over the last almost thirty years of his career.
Women's disconnection from local labour markets: Real lives and policy failure
Authors: Grant Linda
Published: July 2009

This paper is based on research amongst women living in England who are on the margins of the labour market. It analyses why current policy works so inadequately for this group of women, whose existence is often marked by poverty and social exclusion. It emphasizes the significance of the reality of women's lived experiences and the nature of local labour markets, and discusses how and why policy fails to respond to these. Women lack bespoke support and are channelled into `women's jobs', perpetuating gender inequalities in employment and reinforcing precarious relationships with the labour market. In addition, the effect of the key ideas underpinning policy, in particular `welfare dependency' and a `work first' orientation, is to distort the responses to women claimants and to ignore the needs of non-claimant women returners. In conclusion the paper argues that current policy both overlooks the specificity of women's labour market disconnection and contributes to its reproduction.
Empowering the powerful: Challenging hidden processes of marginalization in youth work policy and practice in Belgium
Authors: Coussée Filip , Roets Griet , De Bie Maria
Published: July 2009

On the basis of extensive research, we turn a critical eye on often unnoticed processes of marginalization at play in current youth work policy and practice in Flanders (the Dutch speaking part of Belgium). Although the historical situation seems different from that in the UK, current policies show similar results: vulnerable youth is increasingly monitored into particular target categories and separated into distinct and professionalized youth work initiatives. Inspired by critical class theory, we raise the veil of youth work as a hidden civilization strategy that empowers the yet powerful and has served the often unconscious agenda of enforcing social control on vulnerable youth to create order in late capitalist societies. The perspective of the critical social theorist Hermann Giesecke who perceives youth work as ` politische Bildung' (a process of political socialization) allows us to explore strategies for inclusion which can be implemented to energize future youth work praxis.
Evidence, values and drug treatment policy
Authors: Valentine Kylie
Published: July 2009

Despite the controversial nature of illicit drug treatment, there is a relative lack of research on policy formation in this area. This paper draws on qualitative interviews with service providers and analysis of policy documents, conducted for an Australian National Health and Medical Research Council funded project entitled `Comparing the role of takeaways in methadone maintenance treatment in New South Wales and Victoria', to examine the formation and implementation of drug treatment policy. In particular, it considers two forces widely acknowledged to be important to drug treatment, and often argued to be antithetical to each other: community values and scientific evidence. Separation of the `social' and the `scientific' in treatment is a much-used but conceptually limited distinction. Two alternatives to evidence-based policy are proposed. The first, values-based policy, is increasingly important to critical discussions of social policy and could potentially add much to debates around drug treatment policy. The second alternative is suggested by social studies of science (STS), in particular feminist STS.
Culture, Change and the Meaning of History: Reflections on Richard Lebow's New Theory of International Relations
Authors: Osiander Andreas
Published: July 2009

In my critique of Richard Lebow's new A Cultural Theory of International Relations I highlight a lack of sensitivity to the problem of structural change. Contrary to Lebow's claim to be more attuned to change than existing IR theory, I contend that his exclusive focus on the recurrence of certain behavioural patterns in the course of history is insufficient as a foundation for a new grand theory. Interesting as it may be, this focus is restrictive even with regard to the concept of culture on which it is based. Thus, religion and ideology, which surely must be classified as cultural phenomena, are virtually ignored. Last but not least, I fault the book for its cavalier, indeed often cartoonish, treatment of the historical record. The book falls far short of the `sympathetic reliving' of the past that it promises; the argument is, moreover, seriously impaired by the myriad factual mistakes that the book contains.
A Fanonian Critique of Lebow's A Cultural Theory of International Relations
Authors: Shilliam Robbie
Published: July 2009

Ned Lebow's new project is not so much a cultural theory of international relations as an affective praxis of modernity. Lebow seeks to elucidate the psychical drivers of intersubjective identity formation that dynamically constitute status hierarchies in societies. And through this understanding Lebow holds that present-day possibilities of structural transformations in international relations might be clearly guided by practical reason. In what follows I mount a sympathetic critique of Lebow's affective praxis based upon its effective circumscription of psychical life to elite European men. Lebow pays hardly any attention to the psychic drivers of colonisation and decolonisation as felt by the colonised. Using the work of Frantz Fanon, I shall suggest that shifting the focus to the colonial and post-colonial world brings to light a set of considerations on the psychic sources of affect in modernity that remain obfuscated when the European elite man is conflated as the modern subject.
Psychometric Assessment and Reporting Practices
Authors: Slaney Kathleen L. , Tkatchouk Masha , Gabriel Stephanie M. , Maraun Michael D.
Published: July 2009

The aim of the current study is twofold: (a) to investigate the rates at which researchers assess and report on the psychometric properties of the measures they use in their research and (b) to examine whether or not researchers appear to be generally employing sound/unsound rationales when it comes to how they conduct test evaluations. Based on a sample of 368 articles published in four journals in the year 2004, the findings suggest that, although evidence bearing on score precision/reliability and the internal structure of item responses remains under-reported, researchers appear to be assessing the relationships between test scores and external variables relatively more frequently than in the past. However, findings also indicate that, all told, very few researchers are assessing and reporting on internal score validity, and score precision/reliability, and external score validity, and in that sequence, suggesting that applied researchers may not always be adopting sound test-evaluative rationales in their psychometric assessments.
Simulation of Phenolic Compounds Transformations and Interactions in an In Vitro Model of the Human Alimentary Tract
Authors: Tarko T. , Duda-Chodak A. , Tuszyński T.
Published: July 2009

Phenolic compounds play an important role in the defense system of the human organism against reactive oxygen species. They are present mainly in fruit and vegetables, but their bioavailability is the key factor determining their concentration in blood and tissues. The aim of this article was to study the transformations that apple polyphenols undergo during digestion. An in vitro model with dialysate membranes simulating the human alimentary tract was used for evaluating the composition and antioxidant properties of fresh apples and products of their digestion in dialysates. Epicatechin, chlorogenic acid, and procyanidins were the main antioxidant compounds in the whole fruits and flesh of the two varieties of apples analyzed. In the apple peel additionally quercetin glycosides were present. As a result of in vitro digestion both polyphenolic compounds concentration and the antioxidant activity of the dialysates increased as compared to the raw materials (from 35% to 95% and from 50% to 236%, respectively). In the simulated alimentary tract, it was proved that procyanidins disintegrate to (+)catechin, which is well absorbed from the small intestine, while chlorogenic acid and quercetin glycosides were characterized by a low bioavailability.
The Role of Domestic Architecture in the Structuring of Memory
Authors: Davidson Tonya
Published: July 2009

In this article, through personal narratives of three houses she knows, the authors asks, Can houses remember? She suggests that through processes of inhabitation, houses become “second bodies” that remember in two ways. Houses remember and haunt as they animate the memories of previous inhabitants, memories that become embodied by the houses and the current dwellers. Houses also embody histories of design, reflective of broader social attitudes toward intimate places. Second, houses remember as they are imbued with the responsibilities of representing in material form the virtualities of childhood, acting as Bachelard's “land of Motionless Childhood.” More broadly, houses become dwelling places through processes of inhabitation and appropriation. These processes involve the synthesis of memories of others animated by a house and one's own experiences of inhabitation.
Review Article: Influence of occupational stress on mental health among Chinese off-shore oil workers
Authors: Chen Wei-Qing , Wong Tze-Wai , Yu Tak-Sun
Published: July 2009

Aim: To explore the influence of occupational stress on mental health in off-shore oil production. Methods: A cross-sectional survey was conducted among 561 Chinese off-shore oil workers. The workers were invited to fill in a self-administered questionnaire exploring their socio-demographic characteristics, occupational stress levels, and 12-item general health questionnaire. A hierarchical multiple regression procedure was used to assess the effects of occupational stress on mental health. Results: After controlling for age, educational level, marital status and years of off-shore work, poor mental health was found to have a significant positive association with seven of the nine identified sources of occupational stress. They were: conflict between job and family/social life, poor development of career and achievement at work, safety problems at work, management problems and poor relationship with others at work, poor physical environment of the work place, uncomfortable ergonomic factors at work, and poor organizational structure at work. All of these occupational stress sources together explained 19.9% of the total variance. Conclusions: The results confirmed that occupational stress was a major risk factor for poor mental health among Chinese off-shore oil workers. Reducing or eliminating occupational stressors at work would benefit workers’ mental health.
Philadelphia-positive patients who already harbor imatinib-resistant Bcr-Abl kinase domain mutations have a higher likelihood of developing additional mutations associated with resistance to second- or third-line tyrosine kinase inhibitors
Authors: Soverini Simona , Gnani Alessandra , Colarossi Sabrina , Castagnetti Fausto , Abruzzese Elisabetta , Paolini Stefania , Merante Serena , Orlandi Ester , de Matteis Silvia , Gozzini Antonella , Iacobucci Ilaria , Palandri Francesca , Gugliotta Gabriele , Papayannidis Cristina , Poerio Angela , Amabile Marilina , Cilloni Daniela , Rosti Gianantonio , Baccarani Michele , Martinelli Giovanni
Published: July 2009

Dasatinib and nilotinib are tyrosine kinase inhibitors (TKIs) developed to overcome imatinib resistance in Philadelphia-positive leukemias. To assess how Bcr-Abl kinase domain mutation status evolves during sequential therapy with these TKIs and which mutations may further develop and impair their efficacy, we monitored the mutation status of 95 imatinib-resistant patients before and during treatment with dasatinib and/or nilotinib as second or third TKI. We found that 83% of cases of relapse after an initial response are associated with emergence of newly acquired mutations. However, the spectra of mutants conferring resistance to dasatinib or nilotinib are small and nonoverlapping, except for T315I. Patients already harboring mutations had higher likelihood of relapse associated with development of further mutations compared with patients who did not harbor mutations (23 of 51 vs 8 of 44, respectively, for patients who relapsed on second TKI; 13 of 20 vs 1 of 6, respectively, for patients who relapsed on third TKI).
Expression of the peroxisome proliferator activated receptor γ gene is repressed by DNA methylation in visceral adipose tissue of mouse models of diabetes
Authors: Fujiki Katsunori , Kano Fumi , Shiota Kunio , Murata Masayuki
Published: July 2009

Background

Adipose tissues serve not only as a store for energy in the form of lipid, but also as endocrine tissues that regulates metabolic activities of the organism by secreting various kinds of hormones. Peroxisome proliferator activated receptor γ (PPARγ) is a key regulator of adipocyte differentiation that induces the expression of adipocyte-specific genes in preadipocytes and mediates their differentiation into adipocytes. Furthermore, PPARγ has an important role to maintain the physiological function of mature adipocyte by controlling expressions of various genes properly. Therefore, any reduction in amount and activity of PPARγ is linked to the pathogenesis of metabolic syndrome.

Results

In this study, we investigated the contribution of epigenetic transcriptional regulatory mechanisms, such as DNA methylation, to the expression of the PPARγ gene, and further evaluated the contribution of such epigenetic regulatory mechanisms to the pathogenesis of metabolic syndrome. In 3T3-L1 preadipocytes, the promoter of the PPARγ2 gene was hypermethylated, but was progressively demethylated upon induction of differentiation, which was accompanied by an increase of mRNA expression. Moreover, treatment of cells with 5'-aza-cytideine, an inhibitor of DNA methylation, increased expression of the PPARγ gene in a dose-dependent manner. Methylation in vitro of a PPARγ promoter-driven reporter construct also repressed the transcription of a downstream reporter gene. These results suggest that the expression of the PPARγ gene is inhibited by methylation of its promoter. We next compared the methylation status of the PPARγ promoters in adipocytes from wild-type (WT) mice with those from two diabetic mouse models: +Lepr

db

/+Lepr

db
and diet-induced obesity mice. Interestingly, we found increased methylation of the PPARγ promoter in visceral adipose tissues (VAT) of the mouse models of diabetes, compared to that observed in wild-type mice. We observed a concomitant decrease in the level of PPARγ mRNA in the diabetic mice compared to the WT mice.

Conclusion

We conclude that the expression of PPARγ gene is regulated by DNA methylation of its promoter region and propose that reduced expression of PPARγ owing to DNA methylation in adipocytes of the VAT may contribute to the pathogenesis of metabolic syndrome.
Trefoil Factor-1 (TFF1) Enhances Oncogenicity of Mammary Carcinoma Cells
Authors: Amiry Naeem , Kong Xiangjun , Muniraj Nethaji , Kannan Nagarajan , Grandison Prudence M. , Lin Juan , Yang Yulu , Vouyovitch Cécile M. , Borges Sahra , Perry Jo K. , Mertani Hichem C. , Zhu Tao , Liu Dongxu , Lobie Peter E.
Published: July 2009

The functional role of autocrine trefoil factor-1 (TFF1) in mammary carcinoma has not been previously elucidated. Herein, we demonstrate that forced expression of TFF1 in mammary carcinoma cells resulted in increased total cell number as a consequence of increased cell proliferation and survival. Forced expression of TFF1 enhanced anchorage-independent growth and promoted scattered cell morphology with increased cell migration and invasion. Moreover, forced expression of TFF1 increased tumor size in xenograft models. Conversely, RNA interference-mediated depletion of TFF1 in mammary carcinoma cells significantly reduced anchorage-independent growth and migration. Furthermore, neutralization of secreted TFF1 protein by polyclonal antibody decreased mammary carcinoma cell viability in vitro and resulted in regression of mammary carcinoma xenografts. We have therefore demonstrated that TFF1 possesses oncogenic functions in mammary carcinoma cells. Functional antagonism of TFF1 can therefore be considered as a novel therapeutic strategy for mammary carcinoma.
The Protein-Tyrosine Phosphatase, Src Homology-2 Domain Containing Protein Tyrosine Phosphatase-2, Is a Crucial Mediator of Exogenous Insulin-Like Growth Factor Signaling to Human Trophoblast
Authors: Forbes Karen , West Gemma , Garside Rebecca , Aplin John D. , Westwood Melissa
Published: July 2009

Adequate fetal growth depends on placental transfer of nutrients and gases from the mother; thus, as pregnancy progresses, the placenta must grow to meet the increasing demands of the developing fetus. IGFs control proliferation, differentiation, and survival of trophoblast in first-trimester placenta via intracellular tyrosine kinase signaling cascades, the activation of which is also regulated by tyrosine phosphatases. The protein-tyrosine phosphatase, Src homology-2 domain containing protein tyrosine phosphatase (SHP)-2, is crucial for mouse placental development and is known to mediate IGF actions in other systems. In this study we examined the role of SHP-2 in regulating IGF-mediated proliferation in human trophoblast. Immunohistochemical analysis demonstrated that SHP-2 is expressed strongly in cytotrophoblast and only weakly in syncytium. After small interfering RNA-mediated knockdown of SHP-2 in BeWo choriocarcinoma cells and human first-trimester placental explants, IGF-induced trophoblast proliferation, examined using immunohistochemical analysis of Ki67 and 5-bromo-2′-deoxyuridine incorporation, was significantly reduced (P < 0.05). Kinase activation assays suggested that SHP-2 interacts with the MAPK pathway to mediate these effects. Markers of trophoblast differentiation were elevated after SHP-2 knockdown. This study demonstrates a role for tyrosine phosphatases in human trophoblast and establishes SHP-2 as a component of the IGF signaling pathway that is required for normal placental growth.
Influences of disturbance frequency on the droplet generation for microdroplet deposition manufacture
Authors: Jiang X-S , Qi L-H , Luo J , Zeng X-H
Published: July 2009

The influences of the disturbance frequency on the metal droplet generation are investigated for microdroplet deposition manufacture. The polynomial distribution model is assumed for the jet velocity profile. The optimal disturbance frequency is predicted according to the linear stability analysis. The jet velocity converges and the uniform droplets are generated at the optimal disturbance frequency in the simulation. Experiments have been conducted with the orifice diameter of 150 μm. The formation and diameter of Sn60/Pb40 droplets are estimated under the actions of the different frequency. Results show that the accuracy of the droplet shape and diameter are improved. A narrow-sized log-normal distribution is obtained and the diameter deviation is about 2.59 per cent at the optimal disturbance frequency of 3.89 kHz. Good agreements between the theoretical predictions and experimental values indicate that the optimal disturbance frequency is well predicted with a frequency deviation of less than 1.03 per cent. These works are useful when selecting the operating parameters for manufacturing.
Optimization of the characteristic angles of both front and rear McPherson suspensions on a circular track using multi-body numerical simulation
Authors: Mariotti G Virzì , Ficarra G
Published: July 2009

The research reported in this paper aims to simulate the road-holding of a virtual vehicle using multi-body simulation to estimate both the contact forces between the tyre and ground and the roll motion when cornering. Furthermore, the effect of the characteristic angles on the variation in the forces of the tyre in contact with the ground is studied to determine optimal values for these angles. Emphasis is placed on an average-class vehicle, of which both the external dimensions and mass are chosen appropriately, with a McPherson suspension mounted on both the front and the rear. The characteristic values of the camber and toe-in angles, in both the front and the rear, are optimized for motion in the curve under constant traction. The results of numerical simulation are compared with results from the theory of stability in the curve (given the vertical configuration of the vehicle).
Modelling and parametric investigation of NOx reduction by oxidation precatalyst-assisted ammonia-selective catalytic reduction
Authors: Jung S-C , Yoon W-S
Published: July 2009

Nitrogen oxide (NO x) reduction by the selective catalytic reduction (SCR) system assisted by an oxidation precatalyst is modelled and analytically investigated. The Langmuir—Hinshelwood SCR kinetic scheme with vanadium-based catalyst and ammonia (NH3) reductant in conjunction with the NO—NO2 conversion reaction over a platinum-based catalyst is used. The effects of the ratio of the oxidation precatalyst to the SCR monolith volume, the gas temperature, the space velocity, and the NH3-to-NO x concentration ratio on the de-NO x performance are parametrically examined. The oxidation precatalyst promotes NO x conversion at low temperatures. At intermediate temperatures, the NO x reduction is either activated or deactivated with increase in the space velocity. A higher oxidation precatalyst-to-SCR monolith volume ratio tends to promote the NO x reduction of higher space velocities. At high temperatures, the de-NO x efficiency is very high and insensitive to the space velocity. The NO x conversion efficiency depends on the NH3-to-NO x ratio at low temperatures.
Design and simulation of a variable-timing variable-lift cam mechanism
Authors: Valentini P P , Pennestri E
Published: July 2009

In this paper, the design and the analysis of a mechanical device to achieve the variable timing and the variable lift of a planar cam system, acting on a unique positioning lever, are discussed. The system, which the present authors believe to be novel, is suitable for automotive applications where variable timing and variable displacement of the distribution valves have a positive influence on the overall engine performance. After a general description of the mechanism's kinematic structure and its working principles, the kinematic synthesis algorithm is proposed and a multi-body simulation to investigate the dynamic behaviour is discussed.
Engine optimal operation lines for power-split hybrid electric vehicles
Authors: Ahn Kukhyun , Papalambros P Y
Published: July 2009

The powertrain of a hybrid electric vehicle (HEV) can be operated in either a power-boosting or an energy-saving mode. The first mode is used for responding to the driver's full-load demand and the second for achieving high fuel efficiency given an increased number of degrees of freedom in energy management. Optimization problems for the two operation modes are formulated, and the design spaces are analysed for general power-split architectures. Optimization results are presented and analysed for input-split and compound-split architectures. The analysis leads to the definition of a new concept of HEV optimal operation that improves the conventional idea of engine optimal operation line.
A study on an application of a hybrid break-up model for dimethyl ether atomization in a common-rail injection system
Authors: Kim H J , Suh H K , Lee C S
Published: July 2009

In this study, experimental and numerical investigations were performed to analyse the spray characteristics of dimethyl ether (DME) fuel in a common-rail fuel injection system. In order to analyse the DME fuel spray, overall spray characteristics such as the spray tip penetration, the spray evolution process, and the droplet size distribution were investigated by an application of the hybrid break-up model combined with primary and secondary break-up phenomena. The spray development process and spray tip penetration were measured experimentally from injected DME spray images obtained using a visualization system, while the microscopic characteristics were experimentally measured by a phase Doppler particle analyser system. Calculations based on hybrid break-up models were validated against the experimental results, and the associated break-up constants were optimized after the validation. Based on the optimized break-up constant, the calculated results under various experimental conditions were compared with measured results such as the spray development, the spray tip penetration, the Sauter mean diameter (SMD), and the SMD distribution.
Factors affecting the accuracy of durability estimates in the design of automotive V-belt pulleys using finite element analysis
Authors: Kim B-K , Hong J-P , Kim H-C , Ahn S-H
Published: July 2009

In this study, factors influencing the accuracy of the durability estimation for an automotive V-belt pulley were investigated using finite element analysis (FEA). The bolt load, centrifugal load, and stress history were considered for fatigue life calculations, and their effects on the accuracy of the durability estimation were analysed. The stress history of a pulley that experienced a compressive load induced by belt tension, bolt load, and centrifugal load was determined by performing a consecutive static FEA on the rotating pulley. An estimation of the V-belt pulley fatigue life was based on a damage analysis of 36 load steps. Durability tests for the pulleys were then performed to verify the analysis results. The analysis and experimental results were closely correlated. Additional analyses were performed using the same procedure by isolating each factor and studying its effect on the durability estimation. The results revealed that the bolt load in the pulley analysis was not negligible in improving the accuracy of the analysis, and showed that more stress history must be used for the fatigue life calculations.
Reliability-based design optimization of airframe components
Authors: Patnaik S N , Pai S S , Coroneos R M
Published: July 2009

A stochastic design optimization (SDO) methodology has been developed to design components of an airframe structure. The design is obtained as a function of the risk or reliability. Uncertainties in load, strength, and material properties are treated as distribution functions. Design constraints and optimum weight become functions of reliability. Weight versus reliability traces out an inverted S-shaped graph. The centre of the graph corresponds to 50 per cent probability of success. A heavy design with weight approaching infinity could be produced for a near-zero rate of failure. Weight can be reduced to a small value for the most failure-prone design. Reliability can be changed for different components of an airframe structure. The SDO capability is obtained by combining three codes. MSC/Nastran is the deterministic analysis tool, the fast probability integration of the NESSUS (numerical evaluation of stochastic structures under stress) software is the probabilistic calculator, and NASA (National Aeronautics and Space Administration) Glenn Research Center's testbed CometBoards is the optimizer. The SDO capability requires a finite-element model, a material model, a load model, and a design model. The stochastic optimization concept is illustrated considering an academic example and a real-life raked wingtip structure of the Boeing 767—400 extended range airliner made of metallic and composite materials.
Predictions of laminar flame in aluminium dust clouds with a two-dimensional analytical model
Authors: Jadidi M , Bidabadi M , Hosseini M E
Published: July 2009

In the present study, with the assumption of a laminar, steady and uniform flow and with the purpose of gaining flame speed, quenching distance, lean flammability limit, and temperature distribution, a two-dimensional (2D) analytical model of micro-sized aluminium dust cloud combustion in a channel is presented. In the previous analytical models, energy conservation equations of laminar flame had been solved one-dimensionally and flame speed and quenching distance had been obtained assuming that heat loss to the wall is linear. This model is developed with the assumption that the particle burning rate in the flame front is controlled by the process of oxygen diffusion, and a channel with constant temperature boundary conditions, similar to those of quenching plates and experimental aluminium dust cloud combustion channels, is assumed as well. In order to examine more precisely the impact from the amount of heat loss originating from the channel wall on combustion parameters including flame speed, energy equations are written in two-dimensions. The equations are written in two limiting cases: lean and rich mixtures. Flame structure consists of preheat, reaction, and post-flame zones for the lean mixture and preheat and reaction zones for the rich mixture. Although equations in the lean mixture are solved using the separation of variables method, Laplace method is used for their solution in the rich mixture. By solving the energy equations in each zone and matching the temperature and heat flux at the interfacial boundaries, algebraic equations of flame speed are obtained. The obtained gas temperature distribution in different flame zones in the channel and also flame speed changes in terms of particles' diameter, equivalence ratio, and channel width in both lean and rich mixtures are presented in the results section. Generally, the results of the study shows that solving equations in 2D models leads to higher agreements between the theoretical and experimental results in flame speed, lean limit, and quenching distance terms.
Prediction of unsteady non-linear combustion instability in solid rocket motors
Authors: Montesano J , Greatrix D R , Behdinan K , Fawaz Z
Published: July 2009

The influence of the surrounding motor structure on the appearance of unsteady non-linear axial combustion instability symptoms in a solid rocket motor internal combustion chamber is investigated. The numerical simulation model consists of three coupled physical components, including the combined propellant and motor casing structure, the motor core fluid flow, and the corresponding propellant combustion. A transient frequency-dependent burning-rate model and an updated erosive burning-rate component model are incorporated in the current overall numerical simulation model. The results of simulating a hot-flow unsteady motor firing indicate that structural vibrations directly affect the burning rate and the axial pressure wave development within the chamber that appears as a primary symptom of combustion instability. Comparison of the predicted results with the experimental test results indicates that a good correlation exists between the two, providing support for the present simulation model.
In-flight experiments for delaying laminar—turbulent transition on a laminar wing glove
Authors: Peltzer I , Pätzold A , Nitsche W
Published: July 2009

This article describes in-flight measurements to delay laminar—turbulent transition by means of active Tollmien—Schlichting (TS) wave cancellation. The damping of unstable TS waves in the boundary layer leads to downstream shifting of the laminar—turbulent transition and therefore to the reduction of skin friction. In-flight experiments were carried out using a laminar wing glove for a sailplane. A sensor—actuator system attached to the wing glove consisted of an array of surface hot-wire reference sensors to detect oncoming TS-waves upstream of a membrane actuator and surface hot-wire error sensors downstream of the actuator. The method applied to delay laminar—turbulent transition is based on damping of naturally occurring instabilities through superimposition of the counter wave, which is calculated by a fast digital signal processor using a closed-loop feed-forward control algorithm. The experiments were carried out at flight velocities in the region of 20 m/s, which corresponds to a chord Reynolds number of about 2 million. The results show a damping of ∼ 50 per cent reduction of the local amplitudes of the instabilities. It is anticipated that using an actuator with a high resonance frequency and a minimal reaction time will improve damping significantly in future experiments.
Design and simulation of a poly(vinyl alcohol)—bacterial cellulose nanocomposite mechanical aortic heart valve prosthesis
Authors: Mohammadi H , Boughner D , Millon L E , Wan W K
Published: July 2009

In this study, a polymeric aortic heart valve made of poly(vinyl alcohol) (PVA)—bacterial cellulose (BC) nanocomposite is simulated and designed using a hyperelastic non-linear anisotropic material model. A novel nanocomposite biomaterial combination of 15 wt % PVA and 0.5 wt % BC is developed in this study. The mechanical properties of the synthesized PVA—BC are similar to those of the porcine heart valve in both the principal directions. To design the geometry of the leaflets an advance surfacing technique is employed. A Galerkin-based non-linear finite element method is applied to analyse the mechanical behaviour of the leaflet in the closing and opening phases under physiological conditions. The model used in this study can be implemented in mechanical models for any soft tissues such as articular cartilage, tendon, and ligament.
Biotribological investigation of a multi-tube foot for traction generation in a medical microrobot
Authors: Kim Y-T , Kim D-E
Published: July 2009

In recent years, efforts to develop microrobots for medical applications have been expanding. One of the key design issues in such microrobots is to attain adequate frictional interaction between the robotic foot and the organ tissue. In particular, it is important to generate the necessary frictional force without damaging the tissue. In this work, a design for the robotic foot was proposed on the basis of the frictional behaviour of a tube structure. Fundamental experiments were initially performed to understand the biotribological behaviour of the tube and rod structures. The design was then modified to a multi-tube structure to achieve adequate frictional behaviour. Biotribological investigation of a multi-tube foot in contact with a small intestine specimen of a pig was conducted using a pin-on-reciprocator type biotribotester. It was found that there is an optimum number and arrangement of the tubes for generating high frictional force. Experimental results showed that a nine-tube foot had the highest initial friction coefficient of about 1.5. The major frictional mechanism was determined to be interlocking between the tubes and the surface structures of the intestine specimen. The results of this work will aid the optimum design of frictional surface for medical microrobots and other biological devices.
Parameterization of all stable controllers stabilizing full state information systems and mixed sensitivity
Authors: Orozco R Galindo
Published: July 2009

Analytical expressions for the parameterization of all one- and two-degrees-of-freedom stable controllers stabilizing full state information systems are presented. It is assumed that the strictly proper, lumped, and linear time-invariant nominal plant has a stabilizable realization and is strongly stabilizable, and that the number of entries of the plant state is even and is double the number of entries of the plant input. Right and left coprime factorizations of the transfer function of the plant in terms of the matrices of the plant realization are proposed, the Diophantine equation is solved, and stabilizing controllers are obtained using Youla parameterization. Conditions for strong stability are given, and the free parameters of the stabilizing controllers solving the mixed sensitivity problem are established. The results are illustrated through simulation examples of a half-car active suspension system and a two-degrees-of-freedom planar rotational robot.