bluuebunny/crossref_metadata_2025 huggingface dataset:
Mitochondrial Transporter ATP Binding Cassette Mitochondrial Erythroid Is a Novel Gene Required for Cardiac Recovery After Ischemia/Reperfusion
Authors: Liesa Marc , Luptak Ivan , Qin Fuzhong , Hyde Brigham B. , Sahin Ergun , Siwik Deborah A. , Zhu Zhengkun , Pimentel David R. , Xu X. Julia , Ruderman Neil B. , Huffman Karl D. , Doctrow Susan R. , Richey Lauren , Colucci Wilson S. , Shirihai Orian S.
Published: July 2011

Background

Oxidative stress and mitochondrial dysfunction are central mediators of cardiac dysfunction after ischemia/reperfusion. ATP binding cassette mitochondrial erythroid (ABC-me; ABCB10; mABC2) is a mitochondrial transporter highly induced during erythroid differentiation and predominantly expressed in bone marrow, liver, and heart. Until now, ABC-me function in heart was unknown. Several lines of evidence demonstrate that the yeast ortholog of ABC-me protects against increased oxidative stress. Therefore, ABC-me is a potential modulator of the outcome of ischemia/reperfusion in the heart.

Methods and Results

Mice harboring 1 functional allele of ABC-me (ABC-me
+/−
) were generated by replacing ABC-me exons 2 and 3 with a neomycin resistance cassette. Cardiac function was assessed with Langendorff perfusion and echocardiography. Under basal conditions, ABC-me
+/−
mice had normal heart structure, hemodynamic function, mitochondrial respiration, and oxidative status. However, after ischemia/reperfusion, the recovery of hemodynamic function was reduced by 50% in ABC-me
+/−
hearts as a result of impairments in both systolic and diastolic function. This reduction was associated with impaired mitochondrial bioenergetic function and with oxidative damage to both mitochondrial lipids and sarcoplasmic reticulum calcium ATPase after reperfusion. Treatment of ABC-me
+/−
hearts with the superoxide dismutase/catalase mimetic EUK-207 prevented oxidative damage to mitochondria and sarcoplasmic reticulum calcium ATPase and restored mitochondrial and cardiac function to wild-type levels after reperfusion.

Conclusions

Inactivation of 1 allele of ABC-me increases the susceptibility to oxidative stress induced by ischemia/reperfusion, leading to increased oxidative damage to mitochondria and sarcoplasmic reticulum calcium ATPase and to impaired functional recovery. Thus, ABC-me is a novel gene that determines the ability to tolerate cardiac ischemia/reperfusion.
Sports-Related Sudden Death in the General Population
Authors: Marijon Eloi , Tafflet Muriel , Celermajer David S. , Dumas Florence , Perier Marie-Cécile , Mustafic Hazrije , Toussaint Jean-François , Desnos Michel , Rieu Michel , Benameur Nordine , Le Heuzey Jean-Yves , Empana Jean-Philippe , Jouven Xavier
Published: July 2011

Background—

Although such data are available for young competitive athletes, the prevalence, characteristics, and outcome of sports-related sudden death have not been assessed previously in the general population.

Methods and Results—

A prospective and comprehensive national survey was performed throughout France from 2005 to 2010, involving subjects 10 to 75 years of age. Case detection for sports-related sudden death, including resuscitated cardiac arrest, was undertaken via national ambulance service reporting and Web-based screening of media releases. The overall burden of sports-related sudden death was 4.6 cases per million population per year, with 6% of cases occurring in young competitive athletes. Sensitivity analyses used to address suspected underreporting demonstrated an incidence ranging from 5 to 17 new cases per million population per year. More than 90% of cases occurred in the context of recreational sports. The age of subjects was relatively young (mean±SD 46±15 years), with a predominance of men (95%). Although most cases were witnessed (93%), bystander cardiopulmonary resuscitation was only commenced in 30.7% of cases. Bystander cardiopulmonary resuscitation (odds ratio 3.73, 95% confidence interval 2.19 to 6.39,
P
<0.0001) and initial use of cardiac defibrillation (odds ratio 3.71, 95% confidence interval 2.07 to 6.64,
P
<0.0001) were the strongest independent predictors for survival to hospital discharge (15.7%, 95% confidence interval 13.2% to 18.2%).

Conclusions—

Sports-related sudden death in the general population is considerably more common than previously suspected. Most cases are witnessed, yet bystander cardiopulmonary resuscitation was only initiated in one third of cases. Given the often predictable setting of sports-related sudden death and that prompt interventions were significantly associated with improved survival, these data have implications for health services planning.
The Need for Multiple Measures of Hospital Quality
Authors: Hernandez Adrian F. , Fonarow Gregg C. , Liang Li , Heidenreich Paul A. , Yancy Clyde , Peterson Eric D.
Published: July 2011

Background—

Process and outcome measures are often used to quantify quality of care in hospitals. Whether these quality measures correlate with one another and the degree to which hospital provider rankings shift on the basis of the performance metric is uncertain.

Methods and Results—

Heart failure patients ≥65 years of age hospitalized in the Get With the Guidelines–Heart Failure registry of the American Heart Association were linked to Medicare claims from 2005 to 2006. Hospitals were ranked by (1) composite adherence scores for 5 heart failure process measures, (2) composite adherence scores for emerging quality measures, (3) risk-adjusted 30-day death after admission, and (4) risk-adjusted 30-day readmission after discharge. Hierarchical models using shrinkage estimates were performed to adjust for case mix and hospital volume. There were 19 483 patients hospitalized from 2005 to 2006 from 153 hospitals. The overall median composite adherence rate to heart process measures was 85.8% (25th, 75th percentiles 77.5, 91.4). Median 30-day risk-adjusted mortality was 9.0% (7.9, 10.4). Median risk-adjusted 30-day readmission was 22.9% (22.1, 23.5). The weighted κ for remaining within the top 20th percentile or bottom 20th percentile was ≤0.15 and the Spearman correlation overall was ≤0.21 between the different measures of quality of care. The average shift in ranks was 33 positions (13, 68) when criteria were changed from 30-day mortality to readmission and 51 positions (22, 76) when ranking metric changed from 30-day mortality to composite process adherence.

Conclusions—

Agreement between different methods of ranking hospital-based quality of care and 30-day mortality or readmission rankings was poor. Profiling quality of care will require multidimensional ranking methods and/or additional measures.
NADPH Oxidase 4 Promotes Endothelial Angiogenesis Through Endothelial Nitric Oxide Synthase Activation
Authors: Craige Siobhan M. , Chen Kai , Pei Yongmei , Li Chunying , Huang Xiaoyun , Chen; Christine , Shibata Rei , Sato Kaori , Walsh Kenneth , Keaney John F.
Published: July 2011

Background—

Reactive oxygen species serve signaling functions in the vasculature, and hypoxia has been associated with increased reactive oxygen species production. NADPH oxidase 4 (Nox4) is a reactive oxygen species–producing enzyme that is highly expressed in the endothelium, yet its specific role is unknown. We sought to determine the role of Nox4 in the endothelial response to hypoxia.

Methods and Results—

Hypoxia induced Nox4 expression both in vitro and in vivo and overexpression of Nox4 was sufficient to promote endothelial proliferation, migration, and tube formation. To determine the in vivo relevance of our observations, we generated transgenic mice with endothelial-specific Nox4 overexpression using the vascular endothelial cadherin promoter (VECad-Nox4 mice). In vivo, the VECad-Nox4 mice had accelerated recovery from hindlimb ischemia and enhanced aortic capillary sprouting. Because endothelial nitric oxide synthase (eNOS) is involved in endothelial angiogenic responses and eNOS is activated by reactive oxygen species, we probed the effect of Nox4 on eNOS. In cultured endothelial cells overexpressing Nox4, we observed a significant increase in eNOS protein expression and activity. To causally address the link between eNOS and Nox4, we crossed our transgenic Nox4 mice with eNOS
−/−
mice. Aortas from these mice did not demonstrate enhanced aortic sprouting, and VECad-Nox4 mice on the eNOS
−/−
background did not demonstrate enhanced recovery from hindlimb ischemia.

Conclusions—

Collectively, we demonstrate that augmented endothelial Nox4 expression promotes angiogenesis and recovery from hypoxia in an eNOS-dependent manner.
Change in Friendship Homophily
Authors: Titzmann Peter F. , Silbereisen Rainer K. , Mesch Gustavo S.
Published: July 2011

This longitudinal study investigated friendship homophily (i.e., the preference for intra-ethnic over inter-ethnic friends) among immigrant adolescents in Israel and Germany. Based on acculturation theories and known differences between Israel and Germany in the establishment of Russian-speaking immigrant communities in these countries, it was hypothesized that levels and rates of change in friendship homophily would differ. Associations between context- and acculturation-related variables and levels and rates of change in adolescent friendship homophily were also tested. The sample consisted of 877 Russian Jewish and 358 ethnic German Diaspora migrant adolescents (i.e., migrants returning to the country of their ancestors from the former Soviet Union). Results confirmed higher levels and a less pronounced decrease of friendship homophily in Israel as compared to Germany. Especially acculturation-related variables were found to be best at predicting intercept and slope of friendship homophily. Findings also showed that differences in levels and rates of change in adolescent friendship homophily between both countries could be explained by language use; thus, using the new host language more often appeared to be a crucial variable for lower levels of friendship homophily. Overall, results suggest very similar adaptation processes toward lower friendship homophily in the two countries but at a different pace over time.
Stadtluft Macht Frei (City Air Brings Freedom)
Authors: Yamagishi Toshio , Hashimoto Hirofumi , Li Yang , Schug Joanna
Published: July 2011

This study tested the “city air” hypothesis, which posits that the social constraints prevalent in rural life are weaker in metropolitan areas, freeing metropolitan residents from pressure to suppress their pursuit of individual goals. To do so, we replicated Yamagishi et al.’s vignette study of pen choice. In the first study using a web-based survey of 821 respondents from all prefectures in Japan, choice of a unique color pen was the highest among respondents from metropolitan areas, while respondents from non-urban prefectures were less willing to choose the unique pen. The second study with 1,398 respondents from Tokyo and rural Japan confirmed the findings.
Responding to Adverse Situations Within Exchange Relationships
Authors: Furrer Olivier , Tjemkes Brian V. , Ülgen Aydinlik Arzu , Adolfs Koen
Published: July 2011

When faced with adverse situations in exchange relationships, the people involved are required to respond. Response strategies are reactions to such adverse situations and represent cognitive schemata organized in an integrated structure forming a mental map. Extant response strategy research implicitly assumes that the content and internal structure of response strategies is universal, but with few exceptions, it fails to assess cross-cultural validity, a necessary step to investigate potential cultural variations in response strategy preferences. This study has investigated the cross-cultural validity of a circumplex model in the Netherlands, Switzerland, Turkey, and Japan. The seven response strategies examined attained measurement equivalence, and six were organized in an equivalent circumplex structure in all four countries. The findings also revealed cross-cultural differences in people’s preference to use response strategies. This study therefore contributes to the cross-cultural psychology literature by demonstrating that response strategy content and structure are nearly universal, whereas preferences for using response strategies vary across cultures.
Mexican American Birthweight and Child Overweight
Authors: Hamilton Erin R. , Teitler Julien O. , Reichman Nancy E.
Published: July 2011

Mexican American children have a weight distribution that categorizes them as relatively healthy at birth but relatively unhealthy by age 3. This early life course transition in health based on weight raises the question of whether Mexican American children “outgrow” the epidemiologic paradox of favorable birth outcomes despite social disadvantage or whether their birthweight distribution places them on trajectory for overweight in childhood. We address this question using newly available 9-year follow-up data from the Fragile Families and Child Wellbeing birth cohort study linked to pre-natal medical records. We systematically investigate the roles of birthweight, pre-natal factors, and childhood factors in explaining racial/ethnic differences in childhood overweight. Our main finding is that Mexican American children do outgrow the paradox: Their rates of childhood overweight are higher than expected given their birthweight distribution. Observed pre-natal and childhood factors do not explain the elevated rates of overweight among Mexican American children.
A quantitative study of Web cache replacement strategies using simulation
Authors: Romano Sam , ElAarag Hala
Published: July 2011

The Web has become the most important source of information and communication for the world. Proxy servers are used to cache objects with the goals of decreasing network traffic, reducing user perceived lag and loads on origin servers. In this paper, we focus on the cache replacement problem with respect to proxy servers. Despite the fact that some Web 2.0 applications have dynamic objects, most of the Web traffic has static content with file types such as cascading style sheets, javascript files, images, etc. The cache replacement strategies implemented in Squid, a widely used proxy cache software, are no longer considered ‘good enough’ today. Squid’s default strategy is Least Recently Used. While this is a simple approach, it does not necessarily achieve the targeted goals. We simulate 27 proxy cache replacement strategies and analyze them against several important performance measures. Hit rate and byte hit rate are the most commonly used performance metrics in the literature. Hit rate is an indication of user perceived lag, while byte hit rate is an indication of the amount of network traffic. We also introduce a new performance metric, the object removal rate, which is an indication of CPU usage and disk access at the proxy server. This metric is particularly important for busy cache servers or servers with lower processing power. Our study provides valuable insights for both industry and academia. They are especially important for Web proxy cache system administrators; particularly in wireless ad-hoc networks as the caches on mobile devices are relatively small.
Effect of wool fiber modified by ecologically acceptable ozone-assisted treatment on the pilling of knit fabrics
Authors: Wan Ailan , Yu Weidong
Published: July 2011

Wool fiber was modified using ecologically acceptable ozone-assisted treatment (ECO) in this study. Chemical and mechanical analysis of the treated samples compared with the untreated, Basolan®88 and Kroy-resin-treated ones are reported. Scanning electronic microscopy results show that the crimp was generated and some scales were partially cleaved on the surface of ECO-treated wool fibers. Fourier transform infrared spectra results suggest the absorbency and the oxidation of disulfide bonds increased after the ECO, especially at 1024 cm−1. The crystallinity of the treated wool fiber slightly increased based on the X-ray results. The friction properties of wool fiber samples were also tested. The hairiness and mechanical properties of yarns were tested. The pilling comparative experiments of the corresponding knitted fabrics were conducted with a Martindale fuzzing-pilling and abrasion meter. The pilling grade of knitted fabric comprised of ECO-treated fibers is 3.8 for 5000 abrasion cycles. It is postulated that the surface morphology and physical properties of fibers and the mechanical properties of corresponding yarns of ECO may resist pilling and make pills pull off.
Economic Development Perspectives and the Policy Process
Authors: Stich Bethany , Miller Chad R.
Published: July 2011

State and local governance operates in the context of multiple competing economic development perspectives. This article highlights three perspectives: Thomas Friedman’s flat world metaphor, Richard Florida’s spiky creative class world, and Michael Shuman’s localism, and reviews their resulting implications for a specific case in Mississippi. The examination of whether to revitalize the Columbus and Greenville Railroad in Mississippi or turn it into a recreational trail illustrates that the assumptions derived from these perspectives affects policy process and implementation. The implications are that public administration needs to operate with an agency perspective in the sense expressed in the “Blacksburg Manifesto.”
Patient Safety Attitudes and Behaviors of Graduating Medical Students
Authors: Wetzel Angela P. , Dow Alan W. , Mazmanian Paul E.
Published: July 2011

As North American medical schools reformulate curricula in response to public calls for better patient safety, surprisingly little research is available to explain and improve the translation of medical students’ knowledge and attitudes into desirable patient safety behaviors in the clinical setting. A total of 139 fourth-year medical students at Virginia Commonwealth University, School of Medicine, 96% of the 2010 graduating class, completed the Attitudes toward Patient Safety Questionnaire and a self-report of safety behaviors. The students were exposed to informal discussions of patient safety concepts but received no formal patient safety curriculum. Most students recognized errors and responded with attitudes supportive of patient safety but desired behaviors were less common. In particular, errors went unreported, owing, in part, to the relationships of power and social influence undergirding the traditional authority gradient in the culture of medicine. A deeper understanding of patient safety attitudes, behavior, and medical culture is required to better inform instructional design decisions that influence desired patient safety behaviors and improve patient care.
The broken curve: Effects of the Norwegian manifesto against bullying
Authors: Roland Erling
Published: July 2011

The first Norwegian Manifesto (Manifesto-I) Against Bullying was launched by the Prime Minister in autumn 2002 and lasted for 2 years. A background for Manifesto-I was that school bullying had increased almost linearly in Norway with over 60% more victims and bullies since 1995. During the manifest period, the percentage of victims and bullies were reduced. After that period, from 2004 to 2008, the percentage of victims and bullies increased again, although a second manifesto (Manifesto-II) was launched by a new government in January 2006. The changes for both victims and bullies were significant. Preconditions for the success of the Manifesto-I and the activities comprising it are described, analysed, and compared with the Manifesto-II period.
Promoting relationships and eliminating violence in Canada
Authors: Pepler Debra , Craig Wendy
Published: July 2011

The Promoting Relationships and Eliminating Violence Network (PREVNet) involves Canadian researchers and national organizations working to promote healthy relationships and prevent bullying. In this paper, we provide the rationale for establishing PREVNet, a description of the work of the network, and an assessment of the success of PREVNet. PREVNet’s strategic plan focuses on enhancing the practice of those who work with children and youth through knowledge mobilization under four strategy pillars: education and training, assessment and evaluation, prevention and intervention, and policy and advocacy. For this paper, we focus on proximal indicators of PREVNet’s success: growth of the network, participation in network activities, and development of knowledge mobilization resources. We illustrate that building partnerships with national organizations has been highly effective in the generation and dissemination of knowledge relating to children’s healthy development and healthy relationships.
National Safe Schools Framework: Policy and practice to reduce bullying in Australian schools
Authors: Cross Donna , Epstein Melanie , Hearn Lydia , Slee Phillip , Shaw Therese , Monks Helen
Published: July 2011

In 2003 Australia was one of the first countries to develop an integrated national policy, called the National Safe Schools Framework (NSSF), for the prevention and management of violence, bullying, and other aggressive behaviors. The effectiveness of this framework has not yet been formally evaluated. Cross-sectional data collected in 2007 from 7,418 students aged 9 to 14 years old and 453 teachers from 106 representative Australian schools were analyzed to determine teachers’ perceptions about the extent of implementation of the NSSF, teachers’ capacity to address student bullying, and students’ reports of bullying in their school, 4 years following the framework’s dissemination. While methodological issues limit the findings, schools appear not to have widely implemented the recommended safe school practices, teachers appear to need more training to address bullying, especially covert bullying, and bullying prevalence among students seems relatively unchanged compared to Australian data collected 4 years prior to the launch of the NSSF.
National strategy for violence prevention in the Austrian public school system: Development and implementation
Authors: Spiel Christiane , Strohmeier Dagmar
Published: July 2011

As a result of a quick succession of several spectacular events in schools, and the ensuing public discussion on the high rates of bullying in Austria, a national strategy for violence prevention in schools and preschools has been developed. In formulating the strategy, a systematic procedure involving international experts and a number of local stakeholders was applied. Six activity domains—(a) policy and advocacy, (b) information and public relations, (c) networking and cooperation, (d) knowledge transfer and education, (e) prevention and intervention, (f) evaluation and research—and the steps necessary for implementation were defined. This paper presents the national strategy. One measure, the Viennese Social Competence Training (ViSC) program, and the results obtained with prior implementations of it on the class level, are described in greater detail. Finally, a summary and a brief outlook for future prospects are provided.
Strategy as Practice and the Narrative Turn
Authors: Fenton Christopher , Langley Ann
Published: July 2011

This paper argues that organizational communication research, and in particular a perspective that focuses on narrative, can contribute in important ways to understanding the practices of strategy. Narrative is believed to be critical to sensemaking in organizations, and multiple levels and forms of narrative are inherent to strategic practices. For example, narrative can be found in the micro-stories told by managers and others as they interact and go about their daily work, in the formalized techniques for strategy-making whether or not the techniques are explicitly story-based, in the accounts people give of their work as strategy practitioners, and in the artefacts produced by strategizing activity. After exploring applications of narrative approaches to strategy praxis, practices, practitioners and text, we review two concepts that might serve to integrate micro and macro levels of analysis. Overall, narrative is seen as a way of giving meaning to the practice that emerges from sensemaking activities, of constituting an overall sense of direction or purpose, of refocusing organizational identity, and of enabling and constraining the ongoing activities of actors.
Secret Agencies: The Communicative Constitution of a Clandestine Organization
Authors: Stohl Cynthia , Stohl Michael
Published: July 2011

This special issue challenges scholars to consider the theoretical, methodological, and practical implications of viewing organizations as ‘constituted in and through human communication.’ Interrogating the work of one of the most influential approaches to the study of the constitutive nature of organizing, the oeuvre of James Taylor and his colleagues or what has become known as the Montreal School, we identify an implicit assumption of organizational transparency. We suggest that unpacking ‘the transparency principle’ helps build a richer framework that builds upon the foundations of the Montreal School, facilitates empirical inquiry, and highlights several aspects of the social context which are typically taken for granted within organizational studies. Expanding Taylor et al.’s orientation to clandestine organizations, we address the question posed by the editors in the call for papers: ‘How does a communication-as-constitutive of organization’s perspective shape understandings of the organization’s embeddedness in social contexts?’ Clandestine organizations embody secret agency and intriguing possibilities for understanding the ways in which social actors communicatively constitute organizations. The metaconversations of clandestine organizing take place in a complex socio-political historical context, and exploration of these metaconversations not only furthers our understanding of illicit and clandestine systems but also provides new insights into the communicative constitution of contemporary organizations in general.
Organizations as Discursive Constructions: A Foucauldian Approach
Authors: Leclercq-Vandelannoitte Aurélie
Published: July 2011

A growing body of literature suggests that communication constitutes organizations, but this argument requires refinement to address its remaining flaws. This essay suggests the tremendous potential of using Michel Foucault’s work to grasp the underlying meaning of this argument and to respond to its shortcomings. The proposed Foucauldian-based process model highlights links across Foucault’s main lines of thought, applied to the relationships among technology, discourse, discipline, control, subject, and identity in an organization. By reframing the concept of technology as a discursive and nondiscursive practice that constrains and enables everyday life, this approach offers better understanding of the argument that communication constitutes organizations. The conceptual model also serves as a backdrop for exploring a problematic field situation with a case study. Technology appears part of processes by which technology, organizations, and subjects get redefined. The organization is dynamically constituted as an evolving, political, negotiated order through power–knowledge relationships.
Potential effectiveness of three different treatment approaches to improve minimal to moderate arm and hand function after stroke – a pilot randomized clinical trial
Authors: Khan Christine Meier , Oesch Peter R , Gamper Urs N , Kool Jan P , Beer Serafin
Published: July 2011

Objective: To test a study design and explore the feasibility and potential effects of conventional neurological therapy, constraint induced therapy and therapeutic climbing to improve minimal to moderate arm and hand function in patients after a stroke.

Method: A pilot study with six-month follow-up in patients after stroke with minimal to moderate arm and hand function admitted for inpatient rehabilitation was performed. Participants were randomly allocated to one of three treatment approaches. Main outcomes were improvement of arm and hand function and adverse effects.

Results: 283 patients with stroke were screened for inclusion over a two-year period, out of which fourtyfour were included. All patients could be treated according to the protocol. Improvement of arm and hand function was significantly higher in conventional neurological therapy and constraint induced therapy compared with therapeutic climbing at discharge, and at six months follow-up ( P < 0.05, effect size = 0.56–0.76). No significant differences in arm and hand function were observed between constraint induced therapy and conventional neurological therapy. Constraint induced therapy participants were significantly less at risk of developing shoulder pain at six months follow-up compared with the other participants ( P < 0.05, effect size = 0.82 and 1.79, respectively).

Conclusions: The study design needs adaptation to accommodate the stringent inclusion criteria leading to prolonged study duration. Constraint induced therapy seems to be the optimal approach to improve arm and hand function and minimize the risk of shoulder pain for patients with minimal to moderate arm hand function after stroke in the intermediate term.
Sizing of delamination using time-of-flight of the fundamental symmetric Lamb modes
Authors: Ramadas C. , Hood Avinash , Padiyar Janardhan , Balasubramaniam Krishnan , Joshi Makarand
Published: July 2011

In this study, a procedure is devised, using the fundamental symmetric Lamb mode (So) to estimate the size of an impact-induced delamination at the bottom interface of a composite laminate, which has been subjected to a low-velocity impact. When S o mode incidents at the edge of delamination, it propagates independently in 0° layer and the rest of layers. Based on the propagation of So mode in the delaminated region, an expression is derived, which can estimate the size of interface delamination using measured arrival times or Time-of-Flight (ToF) of So modes. Numerical simulations were carried out on glass/epoxy (GFRP) cross-ply laminates ([0/902] s) to confirm the derived expression and eventually it was validated through experiments carried out on [0/90/0] GFRP laminates. Moreover, the minimum detectable size of delamination through the proposed method was estimated analytically and verified through numerical simulations.
Factors to Consider for Optimal Span of Control in Community Supervision Evidence-Based Practice Environments
Authors: Armstrong Gaylene S.
Published: July 2011

In the face of budgetary constraints, legislative discussions in Iowa have focused on fiscal savings through an increased probation/parole supervisor to officer ratio, resulting in a reduced number of supervisory staff. Ramifications of this change, given the concurrent implementation of evidence-based practices (EBP), are unknown, given the lack of existing research on rubric for span of control decisions within community corrections agencies. Interviews with stakeholders in both Iowa and a national convenience sample led to a development of factors that should be considered in the future, including an agency’s level of task complexity, the workforce skill level, and the work environment, such as the dynamic nature of assigned tasks. Participants perceived high span of control ratios in a typical community corrections environment would challenge the initial implementation of an effective EBP approach. Policy and practical implications are discussed.
Studies on thermal and dielectric properties of Octa (maleimido phenyl) silsesquioxane (OMPS) - polybenzoxazine (PBZ) hybrid nanocomposites
Authors: Vengatesan M.R. , Devaraju S. , Kumar A. Ashok , Alagar M.
Published: July 2011

Polybenzoxazine (PBZ) hybrid nanocomposites were prepared from new type of allyl-terminated benzoxazine monomer and various weight percentage of Octa (maleimido phenyl) silsesquioxane (OMPS). The allyl terminal benzoxazine monomer was synthesized from 1,1-bis (3-methyl-4-hydroxy phenyl) cyclohexane with allyl amine and formaldehyde through Mannich condensation and it was characterized by using Fourier transform infrared, 1H-NMR and 13C-NMR spectroscopy. Data from differential scanning calorimetry (DSC) analysis shows that the newly synthesized benzoxazine monomer (BZ-Cy-al) begins to show ring opening polymerization at lower temperature than that of conventional allyl terminal benzoxazine (BZ-al).Thermal properties of hybrid nanocomposites were analysed by using DSC and thermogravimetric analyser. The POSS-PBZ nanocomposites possess higher glass transition temperature and thermal stability than that of neat PBZ. Dielectric properties of hybrid polybenzoxazine nanocomposites were found decreasing with an increase in the OMPS content. The water absorption properties of hybrid polybenzoxazine nanocomposites decrease with increase in OMPS content. A homogeneous morphological behavior of the hybrid nanocomposites were studied by X-ray diffraction, scanning electron microscopy and transmission electron microscopy analysis.
Gear fault detection based on adaptive wavelet packet feature extraction and relevance vector machine
Authors: Li N , Liu C , He C , Li Y , Zha X F
Published: July 2011

In this article, a novel fault detection method based on adaptive wavelet packet feature extraction and relevance vector machine (RVM) is proposed for incipient fault detection of gear. First, ten statistical characteristics in time domain and all node energies of full wavelet packet tree are extracted as candidate features. Then, Fisher criterion is applied to evaluate the discrimination power of each feature. Finally, two optimal features from time domain and wavelet domain, respectively, are selected to be used as inputs to the RVM. Furthermore, moving average is applied to each feature to improve accuracy for online continuous fault detection. By combining wavelet packet transform with Fisher criterion, it is able to adaptively find the optimal decomposition level and select the global optimal features. The RVM, a Bayesian learning framework of statistical pattern recognition, is adopted to train the fault detection model. The RVM was compared with the popular support vector machine (SVM) with the increase of training samples. Experimental results validate the effectiveness of the proposed method, and indicate that RVM is more suitable than SVM for online fault detection.
Design and microfabrication of a constant-force microgripper
Authors: Hajhashemi MS , Barazandeh F , Nejad S Nazari , Nadafi DB R
Published: July 2011

The characterization process of micro- and submicrometre particles in some cases demands their careful handling and placement. In most cases, a well-designed microgripper can address these requirements. The following research is focused on the process of design, finite element analysis, and microfabrication of an innovative compliant constant-force microgripper. This new architecture enables microgripper to handle microcomponents under constant gripping force without using any force control system. This characteristic makes it outstanding in compare to the previous works in literature. The adopted fabrication process is a ultraviolet-assisted vertical etching on polyethylene terephthalate substrate. This process is a well-established process to offer the requirements of high resolution and high aspect ratio in microfabrication of plastic structures. The prototyped sample has been successfully tested and its performance during micro-assembly process has been verified.
Development of the process model for plunge grinding and optimization of grinding process
Authors: Choi J , Lee C W , Park J-H
Published: July 2011

This article presents improved grinding roughness model established for cylindrical plunge grinding though analysing the existing roughness models. The proposed roughness model is to consider the uncertain effects of grinding, such as changes of grinding conditions and circumstance, as grinding procedure is progressed. In order to consider the uncertain effect of grinding, the time delay between programmed and actual infeed rate of grinding table is selected as weighting factor of the proposed roughness model. The developed roughness model is also used for the optimization algorithm of grinding procedure. Optimization algorithm in this study is constructed to minimize the grinding cost and to obtain the optimized dressing and grinding conditions under grinding constraints such as no-burn condition, limitation of roughness of workpiece, grinding power, etc. The optimized results also give an optimized dressing interval in batch production. The used optimization algorithm is an Evolutionary Strategy algorithm, and performance of the proposed algorithm was evaluated with experiments.
A modified wave approach for calculation of natural frequencies and mode shapes in arbitrary non-uniform one-dimensional waveguides
Authors: Khoshbayani-Arani M , Rasekh-Saleh N , Nikkhah-Bahrami M
Published: July 2011

In this article, using the wave propagation method, the natural frequencies and mode shapes of an arbitrary non-uniform one-dimensional waveguide are calculated. The non-uniform rods and beams are partitioned into several continuous segments with constant cross-sections, for which there exists an exact analytical solution. At the end of each segment, waves in positive and negative directions are obtained in terms of waves at initial segment and subsequently, the calculations of the mode shapes become simple. By satisfying the boundary conditions, the characteristic equation is obtained and natural frequencies are calculated for both the arbitrary non-uniform rod and beam. Also, by adding waves in positive and negative directions at the end point of each segment, the mode shapes are obtained. To verify the modified wave method presented here, the frequencies and mode shapes of the rod and the beam with a polynomial cross-section having an exact analytical solution are compared and have been proven to be of high accuracy. Besides, comparisons of finite element method are also included. Therefore, this method can also be used to calculate the natural frequencies and mode shapes of rods and beams with any arbitrary variable cross-section for which no analytical solution is available. For the ‘Modified Wave Approach’ developed here, dimensions of transmission matrix remain constant if the number of segments is increased, while in general wave propagation method, dimensions of transmission matrix increase upon increasing the number of segments. Besides this novelty, this method has the advantage that it gives all the natural frequencies and mode shapes, unlike other approximate methods such as weighted residual, Rayleigh–Ritz, and finite difference methods which have their own shortcomings such as limited number of natural frequencies. Also, since each segment has an exact analytical solution, in contrast to other approximate methods, much higher accuracy is obtained even with only a few number of partitions.
The activity airflow detection of vehicle intake system using hot-film anemometry sensors instrument
Authors: Ma R-H
Published: July 2011

The goal of this study is to develop an airflow meter sensor for the detection of vehicle intake system in internal combustion engines. The study uses micro-electromechanical process technology to develop a hot-film flow meter with an alumina substrate and platinum film heater; the hot-line method is used to create a micro-airflow anemometry meter sensor relying on variations in resistance of the platinum film corresponding to different wind velocities at the set temperatures. The alumina plate used in this study is produced by polishing an alumina substrate; a platinum film is then deposited on the plate to complete the micro-heater used in the sensor. Resistance on the sensor side varies as gas flows through the sensor, and the instrument determines airflow velocity on the basis of the changes in resistance caused by gas flow differences. Airflow velocities ranging from 10 to 60 m/s are used to test. Signals of change in resistance display a regular slope, indicating that the relationship between the changes in airflow velocity remains predictable throughout the sensing range. Therefore, the sensor can achieve its purpose of airflow measurement completely.
Non-linear stability analysis of floating ring bearings using Hopf bifurcation theory
Authors: Amamou A , Chouchane M
Published: July 2011

Floating ring bearings are used to support and guide rotors in several high-speed rotating machinery applications. They are usually credited for lower heat generation and higher vibration suppressing ability. Similar to conventional hydrodynamic bearings, floating ring bearings may exhibit unstable behaviour above a certain stability critical speed. Linear stability analysis is usually applied to predict the stability threshold speed. Non-linear stability analysis, however, is needed to predict the presence and the size of stable limit cycles above the stability threshold speed or unstable limit cycles below the stability critical speed. The prediction of limit cycles is an important step in bearing stability analysis. In this article, a non-linear dynamic model is derived and used to investigate the stability of a perfectly balanced symmetric rigid rotor supported by two identical floating ring bearings near the critical stability boundaries. The fluid film hydrodynamic reactions of the floating ring bearings are modelled by applying the short bearing theory and the half Sommerfeld solution. Hopf bifurcation theory is then utilized to determine the existence and the approximate size of stable and unstable limit cycles in the neighbourhood of the stability critical speed depending on the bearing design parameters. Numerical integration of the non-linear equations of motion is then carried out in order to compare the trajectories obtained by numerical integration to those obtained analytically using Hopf bifurcation analysis. Stability boundary curves for typical bearing design parameters have been decomposed into boundaries with supercritical stable limit cycles and boundaries with subcritical unstable limit cycles. The shape and size of the limit cycles for selected bearing parameters are presented using both analytical and numerical approaches. This article shows that floating ring stability boundaries may exhibit either stable supercritical limit cycles or unstable subcritical limit cycles predictable by Hopf bifurcation.
Predictions of laminar flame in aluminium dust clouds with a cylindrical two-dimensional analytical model
Authors: Memarzadeh M , Bidabadi M , Jadidi M , Sedaghat A
Published: July 2011

A simple two-dimensional analytical model of laminar flame in aluminium dust clouds is developed for predicting temperature profiles, flame speed, and flammability limit. This study follows previous studies, in which the models were developed in one-dimensional and 2D in Cartesian coordinate forms, and considers cylindrical coordinates since a tubular space is where most of the experimental works on the subject of dust combustion have been carried out. This article aims mainly to study the effect of the heat loss that happens from the surrounding wall on important combustion parameters including the flame speed and lean flammability limit, with more accuracy. The equations are written in the fuel–lean condition and a tube with constant temperature boundary conditions is assumed as well. The zones constructing the structure of a flame include preheat, reaction, and post-flame zones, for which the equations are solved using the method of separation of variables. The model is used to generate a correlation for the variations of flame speeds in terms of particles’ diameter, equivalence ratio, and tube diameter. The results show that the flame speed increases with decreasing particle size. It increases with increasing equivalence ratio and the tube diameter, as well.
Dynamic comparison of different types of slab track and ballasted track using a flexible track model
Authors: Blanco-Lorenzo J , Santamaria J , Vadillo E G , Oyarzabal O
Published: July 2011

The dynamic performance of a ballasted track and three types of slab track is analysed and compared by means of a comprehensive dynamic model of the train–track system, generated using two commercial analysis software packages: the commercial multibody system (MBS) analysis software SIMPACK and the finite element method (FEM) analysis software NASTRAN. The use of a commercial MBS software makes it possible to include, in a reliable way, models of advanced non-linear wheel–rail contact as well as complex elements or joints in the vehicle model, while the FEM the flexibility of the rail and the slab to be taken into account. As a result, a combined MBS–FEM representation of the vehicle–track model is integrated into the MBS software, which allows for the study of dynamic phenomena in a wide frequency range. In this study, other simpler approaches for modelling the dynamic vehicle–track interaction are also considered, such as pure multibody or FE representations of the whole vehicle–track system. The quality of the results obtained with the different types of models used is analysed, and some conclusions are put forth regarding the possible validity of rather simple train–track interaction model types under certain conditions as well as the most suitable configuration of the most complex models.
Satellite constellations in inclined multi-stationary orbits
Authors: Ortore E , Ulivieri C , Bunkheila F
Published: July 2011

After a general approach to the concept of multi-synchronous orbit (MSO) missions, which includes some past investigations on the use of orbits alternative to the Geostationary one, a selection of satellite constellations in MSOs, providing continuous and complete longitudinal coverage of the Earth, has been carried out. The concept of four-leaf clover system (FLCS), already introduced in the past for the equatorial–tropical belt, has been generalized, taking into account orbit inclinations up to the critical value (63.43°) and the consequent different operational scenarios. The temporal evolution of ground tracks and coverage of periodic orbits have been investigated in depth. A comparison between a Geostationary system and an inclined FLCS, in terms of costs and performance, pointed out the advantages of using these latter orbits.
A comparison of neural networks for FDI of rolling element bearings – demonstrated on experimental rig data
Authors: Samy I , Whidborne J , Postlethwaite I
Published: July 2011

In this article, a fault detection and isolation (FDI) approach for bearing faults in rotating machinery using a combination of vibration analysis and expert systems via neural networks (NNs) is proposed. The NN chosen is the extended minimum resource allocating network (EMRAN) radial basis function (RBF) due to its good performance characteristics. While the EMRAN RBF NN structure is itself not novel, the application to bearing FDI has, to the author's knowledge, been less frequently explored. The EMRAN RBF NN is used for pattern classification of four types of bearing health conditions: healthy, inner race, outer race, and ball bearing faults. A machine fault simulator is used to simulate the bearing faults and the input nodes of the NN include five features extracted from the time-domain vibration data: peak, root mean square, standard deviation, kurtosis, and normal negative log-likelihood value. Using real experimental data from a machine fault simulator, it was found that a 3-7-4 EMRAN RBF NN structure outperforms a 5-20-4 multilayered perceptron NN with zero false alarms, fewer undetected faults, higher pattern correlation factors, and faster execution times.