bluuebunny/crossref_metadata_2025 huggingface dataset:
Using immersive healthcare simulation for physiology education: initial experience in high school, college, and graduate school curricula
Authors: Oriol Nancy E. , Hayden Emily M. , Joyal-Mowschenson Julie , Muret-Wagstaff Sharon , Faux Russell , Gordon James A.
Published: September 2011

In the natural world, learning emerges from the joy of play, experimentation, and inquiry as part of everyday life. However, this kind of informal learning is often difficult to integrate within structured educational curricula. This report describes an educational program that embeds naturalistic learning into formal high school, college, and graduate school science class work. Our experience is based on work with hundreds of high school, college, and graduate students enrolled in traditional science classes in which mannequin simulators were used to teach physiological principles. Specific case scenarios were integrated into the curriculum as problem-solving exercises chosen to accentuate the basic science objectives of the course. This report also highlights the historic and theoretical basis for the use of mannequin simulators as an important physiology education tool and outlines how the authors' experience in healthcare education has been effectively translated to nonclinical student populations. Particular areas of focus include critical-thinking and problem-solving behaviors and student reflections on the impact of the teaching approach.
Development and evaluation of a multimedia e-learning resource for electrolyte and acid-base disorders
Authors: Davids Mogamat Razeen , Chikte Usuf M. E. , Halperin Mitchell L.
Published: September 2011

This article reports on the development and evaluation of a Web-based application that provides instruction and hands-on practice in managing electrolyte and acid-base disorders. Our teaching approach, which focuses on concepts rather than details, encourages quantitative analysis and a logical problem-solving approach. Identifying any dangers to the patient is a vital first step. Concepts such as an “appropriate response” to a given perturbation and the need for electroneutrality in body fluids are used repeatedly. Our Electrolyte Workshop was developed using Flash and followed an iterative design process. Two case-based tutorials were built in this first phase, with one tutorial including an interactive treatment simulation. Users select from a menu of therapies and see the impact of their choices on the patient. Appropriate text messages are displayed, and changes in body compartment sizes, brain size, and plasma sodium concentrations are illustrated via Flash animation. Challenges encountered included a shortage of skilled Flash developers, budgetary constraints, and challenges in communication between the authors and the developers. The application was evaluated via user testing by residents and specialists in internal medicine. Satisfaction was measured with a questionnaire based on the System Usability Scale. The mean System Usability Scale score was 78.4 ± 13.8, indicating a good level of usability. Participants rated the content as being scientifically sound; they liked the teaching approach and felt that concepts were conveyed clearly. They indicated that the application held their interest, that it increased their understanding of hyponatremia, and that they would recommend this learning resource to others.
GATA6 reporter gene reveals myocardial phenotypic heterogeneity that is related to variations in gap junction coupling
Authors: Rémond Mathieu C. , Iaffaldano Grazia , O'Quinn Michael P. , Mezentseva Nadejda V. , Garcia Victor , Harris Brett S. , Gourdie Robert G. , Eisenberg Carol A. , Eisenberg Leonard M.
Published: September 2011

This study examined transgenic mice whose expression of a β-galactosidase (lacZ) reporter is driven by a GATA6 gene enhancer. Previous investigations established that transcription of the transgene was associated with precardiac mesoderm and primary heart tube myocardium, which decreased progressively, so that its expression was no longer observed within ventricular myocardium by midgestation. Expression of this reporter in the adult was investigated for insights into myocyte homeostasis and cardiovascular biology. Morphometric analysis determined that <1% of myocytes, often found in small clusters, express this GATA6-associated reporter in the adult heart. LacZ expression was also found in the ascending aorta. Myocardial expression of the transgene was not associated with a proliferative phenotype or new myocyte formation, as lacZ-positive myocytes neither labeled with cell division markers nor following 5-bromodeoxyuridine pulse-chase experimentation. Despite exhibiting normal adherens junctions, these myocytes appeared to exhibit decreased connexin 43 gap junctions. Treatment with the gap junctional blocker heptanol both in vivo and in culture elevated myocardial β-galactosidase activity, suggesting that deficient gap junctional communication underlies expression of the transgenic reporter. LacZ expression within the myocardium was also enhanced in response to cryoinjury and isoproterenol-induced hypertrophy. These results reveal a previously uncharacterized phenotypic heterogeneity in the myocardium and suggest that decreased gap junctional coupling leads to induction of a signaling pathway that utilizes a unique GATA6 enhancer. Upregulation of lacZ reporter gene expression following cardiac injury indicates this transgenic mouse may serve as a model for examining the transition of the heart from healthy to pathological states.
Decreased tetrahydrobiopterin and disrupted association of Hsp90 with eNOS by hyperglycemia impair myocardial ischemic preconditioning
Authors: Vladic Nikolina , Ge Zhi-Dong , Leucker Thorsten , Brzezinska Anna K. , Du Jian-Hai , Shi Yang , Warltier David C. , Pratt Phillip F. , Kersten Judy R.
Published: September 2011

Cardioprotection by ischemic preconditioning (IPC) is impaired during hyperglycemia, but the mechanisms underlying this phenomenon are poorly understood. This study investigated the role of hyperglycemia to adversely modulate tetrahydrobiopterin (BH4) and heat shock protein 90 (Hsp90) during cardioprotection by IPC. Rabbits or mice underwent 30 min of coronary occlusion followed by reperfusion with or without IPC in the presence or absence of hyperglycemia. IPC significantly ( P < 0.05) decreased myocardial infarct size (46 ± 1 to 19 ± 2% of the area at risk in control and IPC rabbits, respectively) and increased BH4concentrations (HPLC; 7.6 ± 0.2 to 10.2 ± 0.3 pmol/mg protein, respectively), Hsp90-endothelial nitric oxide synthase (eNOS) association (coimmunoprecipitation and Western blotting in mice; 4.0 ± 0.3 to 5.4 ± 0.1, respectively), and the ratio of phosphorylated eNOS/total eNOS. These beneficial actions of IPC on infarct size, BH4, Hsp90/eNOS, and phosphorylated eNOS were eliminated by hyperglycemia. Pretreatment of animals with the Hsp90 inhibitor geldanamycin (0.6 mg/kg) or the BH4synthesis inhibitor diamino-6-hydroxypyrimidine (1.0 g/kg) also eliminated cardioprotection produced by IPC. In contrast, the BH4precursor sepiapterin (2 mg/kg iv) restored the beneficial effects of IPC on myocardial BH4concentrations, eNOS dimerization, and infarct size during hyperglycemia. A-23871 increased Hsp90-eNOS association (0.33 ± 0.06 to 0.59 ± 0.3) and nitric oxide production (184 ± 17%) in human coronary artery endothelial cells cultured in normal (5.5 mM) but not high (20 mM) glucose media. These data indicate that hyperglycemia eliminates protection by IPC via decreases in myocardial BH4concentration and disruption of the association of Hsp90 with eNOS. The results suggest that eNOS dysregulation may be a central mechanism of impaired cardioprotection during hyperglycemia.
β-Catenin signaling is required for TGF-β1-induced extracellular matrix production by airway smooth muscle cells
Authors: Baarsma Hoeke A. , Menzen Mark H. , Halayko Andrew J. , Meurs Herman , Kerstjens Huib A. M. , Gosens Reinoud
Published: September 2011

Chronic inflammatory airway diseases like asthma and chronic obstructive pulmonary disease (COPD) are characterized by airway remodeling with altered extracellular matrix (ECM) deposition. Transforming growth factor-β1 (TGF-β1) is upregulated in asthma and COPD and contributes to tissue remodeling in the airways by driving ECM production by structural cells, including airway smooth muscle. In this study, we investigated the activation of β-catenin signaling and its contribution to ECM production by airway smooth muscle cells in response to TGF-β1. Stimulation of airway smooth muscle cells with TGF-β1 resulted in a time-dependent increase of total and nonphosphorylated β-catenin protein expression via induction of β-catenin mRNA and inhibition of GSK-3. In addition, the TGF-β1-induced β-catenin activated TCF/LEF-dependent gene transcription, as determined by the β-catenin sensitive TOP-flash luciferase reporter assay. Furthermore, TGF-β1 stimulation increased mRNA expression of collagen Iα1, fibronectin, versican, and PAI-1. Pharmacological inhibition of β-catenin by PKF115-584 or downregulation of β-catenin expression by specific small interfering RNA (siRNA) substantially inhibited TGF-β1-induced expression of the ECM genes. Fibronectin protein deposition by airway smooth muscle cells in response to TGF-β1 was also inhibited by PKF115-584 and β-catenin siRNA. Moreover, transfection of airway smooth muscle cells with a nondegradable β-catenin mutant (S33Y β-catenin) was sufficient for inducing fibronectin protein expression. Collectively, these findings indicate that β-catenin signaling is activated in response to TGF-β1 in airway smooth muscle cells, which is required and sufficient for the regulation of ECM protein production. Targeting β-catenin-dependent gene transcription may therefore hold promise as a therapeutic intervention in airway remodeling in both asthma and COPD.
Pulmonary vascular effects of serotonin and selective serotonin reuptake inhibitors in the late-gestation ovine fetus
Authors: Delaney Cassidy , Gien Jason , Grover Theresa R. , Roe Gates , Abman Steven H.
Published: September 2011

Maternal use of selective serotonin (5-HT) reuptake inhibitors (SSRIs) is associated with an increased risk for persistent pulmonary hypertension of the newborn (PPHN), but little is known about 5-HT signaling in the developing lung. We hypothesize that 5-HT plays a key role in maintaining high pulmonary vascular resistance (PVR) in the fetus and that fetal exposure to SSRIs increases 5-HT activity and causes pulmonary hypertension. We studied the hemodynamic effects of 5-HT, 5-HT receptor antagonists, and SSRIs in chronically prepared fetal sheep. Brief infusions of 5-HT (3–20 μg) increased PVR in a dose-related fashion. Ketanserin, a 5-HT 2A receptor antagonist, caused pulmonary vasodilation and inhibited 5-HT-induced pulmonary vasoconstriction. In contrast, intrapulmonary infusions of GR127945 and SB206553, 5-HT 1B and 5-HT 2B receptor antagonists, respectively, had no effect on basal PVR or 5-HT-induced vasoconstriction. Pretreatment with fasudil, a Rho kinase inhibitor, blunted the effects of 5-HT infusion. Brief infusions of the SSRIs, sertraline and fluoxetine, caused potent and sustained elevations of PVR, which was sustained for over 60 min after the infusion. SSRI-induced pulmonary vasoconstriction was reversed by infusion of ketanserin and did not affect the acute vasodilator effects of acetylcholine. We conclude that 5-HT causes pulmonary vasoconstriction, contributes to maintenance of high PVR in the normal fetus through stimulation of 5-HT 2A receptors and Rho kinase activation, and mediates the hypertensive effects of SSRIs. We speculate that prolonged exposure to SSRIs can induce PPHN through direct effects on the fetal pulmonary circulation.
A Novel MLL5 Isoform That Is Essential to Activate E6 and E7 Transcription in HPV16/18-Associated Cervical Cancers
Authors: Yew Chow Wenn , Lee Pei , Chan Wai Keong , Lim Vania Kai Jun , Tay Sun Kuie , Tan Theresa M.C. , Deng Lih-Wen
Published: September 2011

Human papillomavirus (HPV) is the primary cause of human cervical cancer. The viral proteins E6 and E7 are essential to transform noncancerous epithelial cells into cancerous carcinomas by targeting key tumor suppressors p53 and retinoblastoma (Rb) proteins, respectively, but the cellular factors involved in E6 and E7 transcription themselves are incompletely understood. In this study, we defined a novel isoform of the mixed lineage leukemia 5 gene (MLL5β) as a specific and critical regulator of E6 and E7 transcription in cervical carcinoma cells. MLL5β is present in HPV16/18-positive cells including human primary cervical carcinoma specimens. Interaction of MLL5β with the AP-1–binding site at the distal region of the HPV18 long control region led to activation of E6/E7 transcription. Conversely, RNA interference–mediated knockdown of MLL5β downregulated both E6 and E7 expression. MLL5β downregulation was sufficient to restore p53 protein levels and reduce Rb phosphorylation, thereby reactivating apoptosis and cell-cycle checkpoints. By defining this novel MLL5β isoform and its specific critical role in activating E6/E7 gene transcription in HPV16/18-induced cervical cancers, our work highlights the potential of MLL5β as a biomarker and new therapeutic target in primary HPV–induced cervical cancers. Cancer Res; 71(21); 6696–707. ©2011 AACR.
Generation of a Mouse Model of Von Hippel–Lindau Kidney Disease Leading to Renal Cancers by Expression of a Constitutively Active Mutant of HIF1α
Authors: Fu Leiping , Wang Gang , Shevchuk Maria M. , Nanus David M. , Gudas Lorraine J.
Published: September 2011

Renal cancers are highly aggressive and clinically challenging, but a transgenic mouse model to promote pathologic studies and therapeutic advances has yet to be established. Here, we report the generation of a transgenic mouse model of von Hippel–Lindau (VHL) renal cancer termed the TRACK model (transgenic model of cancer of the kidney). TRACK mice specifically express a mutated, constitutively active HIF1α in kidney proximal tubule (PT) cells. Kidney histologies displayed by TRACK mice are highly similar to histologies seen in patients with VHL disease, including areas of distorted tubular structure, cells with clear cytoplasm and increased glycogen and lipid deposition, multiple renal cysts, and early onset of clear cell renal cell carcinoma (ccRCC). Distorted tubules in TRACK mice exhibit higher levels of CA-IX, Glut1, and VEGF than tubules in nontransgenic control mice. Furthermore, these tubules exhibit increased numbers of endothelial cells, increased cell proliferation, and increased expression of the human ccRCC marker CD70(TNFSF7). Moreover, PT cells in kidney tubules from TRACK mice exhibit increased genomic instability, as monitored by elevated levels of γH2AX. Our findings establish that activated HIF1α in murine kidney PT cells is sufficient to promote cell proliferation, angiogenesis, genomic instability, and other phenotypic alterations characteristic of human VHL kidney disease, establishing the TRACK mouse as a valid preclinical model of human renal cell carcinoma. Cancer Res; 71(21); 6848–56. ©2011 AACR.
Breast Cancer Subtype-Specific Interactions with the Microenvironment Dictate Mechanisms of Invasion
Authors: Dang Tuyen T. , Prechtl Amanda M. , Pearson Gray W.
Published: September 2011

Most ductal breast carcinoma cells are weakly invasive in vitro and in vivo, suggesting that components of their microenvironment may facilitate a transition from in situ to invasive stages during progression. Here, we report that coculture of mammary fibroblasts specifically triggers invasive behavior in basal-type breast cancer cells through a ligand independent mechanism. When cultured alone in organotypic culture, both basal- and luminal-type breast cancer cells formed noninvasive spheroids with characteristics of ductal carcinoma in situ (DCIS). In contrast, when cocultured with mammary fibroblasts, basal-type spheroids exhibited invasive character whereas the luminal-type spheroids retained a benign and noninvasive duct-like architecture. Real-time imaging and functional studies revealed that the specificity of invasion was linked to a unique capacity of basal-type breast cancer cells to move within spheroids. Mammary fibroblasts induced invasion by triggering basal-type breast cancer cells to convert from a noninvasive program of mammary epithelial morphogenesis to an invasive program of sprouting endothelial angiogenesis. Contrary to the existing invasion models, soluble ligands produced by the fibroblasts were not sufficient to trigger invasion. Instead, basal-type invasion relied upon a Cdc42-dependent reorganization of collagen fibers in the extracellular matrix by fibroblasts. Inhibiting basal-type cell movement with clinically relevant drugs blocked invasion both in organotypic culture and in animals, suggesting a new treatment strategy for early-stage patients. Together our findings establish that fibroblast recruitment by basal-type breast cancer cells into early-stage tumors is sufficient to trigger their conversion from a benign, noninvasive DCIS-like stage to a malignant invasive stage. Furthermore, our findings suggest that different subtypes of breast cancer may require distinct types of contributions from the microenvironment to undergo malignant progression. Cancer Res; 71(21); 6857–66. ©2011 AACR.
Merkel Cell Polyomavirus-Specific CD8+ and CD4+ T-cell Responses Identified in Merkel Cell Carcinomas and Blood
Authors: Iyer Jayasri G. , Afanasiev Olga K. , McClurkan Christopher , Paulson Kelly , Nagase Kotaro , Jing Lichen , Marshak Joshua O. , Dong Lichun , Carter Joseph , Lai Ivy , Farrar Erik , Byrd David , Galloway Denise , Yee Cassian , Koelle David M. , Nghiem Paul
Published: September 2011

Purpose: Merkel cell polyomavirus (MCPyV) is prevalent in the general population, integrates into most Merkel cell carcinomas (MCC), and encodes oncoproteins required for MCC tumor growth. We sought to characterize T-cell responses directed against viral proteins that drive this cancer as a step toward immunotherapy.

Experimental Design: Intracellular cytokine cytometry, IFN-γ enzyme-linked immunospot (ELISPOT) assay, and a novel HLA-A*2402–restricted MCPyV tetramer were used to identify and characterize T-cell responses against MCPyV oncoproteins in tumors and blood of MCC patients and control subjects.

Results: We isolated virus-reactive CD8 or CD4 T cells from MCPyV-positive MCC tumors (2 of 6) but not from virus-negative tumors (0 of 4). MCPyV-specific T-cell responses were also detected in the blood of MCC patients (14 of 27) and control subjects (5 of 13). These T cells recognized a broad range of peptides derived from capsid proteins (2 epitopes) and oncoproteins (24 epitopes). HLA-A*2402–restricted MCPyV oncoprotein processing and presentation by mammalian cells led to CD8-mediated cytotoxicity. Virus-specific CD8 T cells were markedly enriched among tumor infiltrating lymphocytes as compared with blood, implying intact T-cell trafficking into the tumor. Although tetramer-positive CD8 T cells were detected in the blood of 2 of 5 HLA-matched MCC patients, these cells failed to produce IFN-γ when challenged ex vivo with peptide.

Conclusions: Our findings suggest that MCC tumors often develop despite the presence of T cells specific for MCPyV T-Ag oncoproteins. The identified epitopes may be candidates for peptide-specific vaccines and tumor- or virus-specific adoptive immunotherapies to overcome immune evasion mechanisms in MCC patients. Clin Cancer Res; 17(21); 6671–80. ©2011 AACR.
Prevention of Persistent Human Papillomavirus Infection by an HPV16/18 Vaccine: A Community-Based Randomized Clinical Trial in Guanacaste, Costa Rica
Authors: Herrero Rolando , Wacholder Sholom , Rodríguez Ana C. , Solomon Diane , González Paula , Kreimer Aimee R. , Porras Carolina , Schussler John , Jiménez Silvia , Sherman Mark E. , Quint Wim , Schiller John T. , Lowy Douglas R. , Schiffman Mark , Hildesheim Allan
Published: September 2011

Target groups for human papillomavirus (HPV) vaccination are controversial. We evaluated vaccine efficacy (VE) against 1-year persistent infection, stratified by age and sexual behavior, among young women in Costa Rica. We randomized 7,466 healthy women 18 to 25 years of age to HPV16/18 or hepatitis A vaccine (follow-up, 50.4 months). According-to-protocol (ATP) cohorts included compliant HPV-negative women; intention-to-treat (ITT) included all randomized women. ATP VE was 90.9% (95% CI, 82.0–95.9) against HPV16/18 infections, 44.5% against HPV31/33/45 (95% CI, 17.5–63.1), and 12.4% (95% CI, −3.2 to 25.6) against any oncogenic infection. Overall ITT VE against HPV16/18 infections was 49.0%, but ATP and ITT VE almost reached 100% in year 4 of follow-up. ATP efficacy against HPV16/18 was similar by age, but ITT VE was greatest among youngest women (68.9% among those 18–19 years of age; 21.8% among those 24–25 years of age) and 79.8% among virgins. Among previously unexposed women, vaccination is highly efficacious against HPV16/18 and partially against HPV31/33/45. Vaccination is most effective in women and girls before they initiate sexual activity, with programmatic and individual decision implications.

Significance: In an independent trial of the bivalent ASO4-adjuvanted HPV16/18 vaccine (Cervarix) conducted among young women in Costa Rica, we confirmed the high efficacy against HPV16/18 persistent infection and partial cross-protection against HPV31/33/45. Furthermore, efficacy data suggest that the benefit of HPV vaccination is maximal when the vaccine is given to young women before they initiate sexual activity. Cancer Discovery; 1(5): 408–19. ©2011 AACR.

Read the Commentary on this article by Bosch et al., p. 377

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Decadal Trends in Evaporation from Global Energy and Water Balances
Authors: Zhang Yongqiang , Leuning Ray , Chiew Francis H. S. , Wang Enli , Zhang Lu , Liu Changming , Sun Fubao , Peel Murray C. , Shen Yanjun , Jung Martin
Published: September 2011

Satellite and gridded meteorological data can be used to estimate evaporation (E) from land surfaces using simple diagnostic models. Two satellite datasets indicate a positive trend (first time derivative) in global available energy from 1983 to 2006, suggesting that positive trends in evaporation may occur in “wet” regions where energy supply limits evaporation. However, decadal trends in evaporation estimated from water balances of 110 wet catchments do not match trends in evaporation estimated using three alternative methods: 1) , a model-tree ensemble approach that uses statistical relationships between E measured across the global network of flux stations, meteorological drivers, and remotely sensed fraction of absorbed photosynthetically active radiation; 2) , a Budyko-style hydrometeorological model; and 3) , the Penman–Monteith energy-balance equation coupled with a simple biophysical model for surface conductance. Key model inputs for the estimation of and are remotely sensed radiation and gridded meteorological fields and it is concluded that these data are, as yet, not sufficiently accurate to explain trends in E for wet regions. This provides a significant challenge for satellite-based energy-balance methods. Trends in for 87 “dry” catchments are strongly correlated to trends in precipitation (R2 = 0.85). These trends were best captured by , which explicitly includes precipitation and available energy as model inputs.
Markov Chain Models for Hydrological Drought Characteristics
Authors: Akyuz Dilek Eren , Bayazit Mehmetcik , Onoz Bihrat
Published: September 2011

Estimation of drought characteristics such as probabilities and return periods of droughts of various lengths is of major importance in drought forecast and management and in solving water resources problems related to water quality and navigation. This study aims at applying first- and second-order Markov chain models to dry and wet periods of annual streamflow series to reproduce the stochastic structure of hydrological droughts. Statistical evaluation of drought duration and intensity is usually carried out using runs analysis. First-order Markov chain model (MC1) for dry and wet periods is not adequate when autocorrelation of the original hydrological series is high. A second-order Markov chain model (MC2) is proposed to estimate the probabilities and return periods of droughts. Results of these models are compared with those of a simulation study assuming a lag-1 autoregressive [AR(1)] process widely used to model annual streamflows. Probability distribution and return periods of droughts of various lengths are estimated and compared with the results of MC1 and MC2 models using efficacy evaluation statistics. It is found that the MC2 model in general gives results that are in better agreement with simulation results as compared with the MC1 model. Skewness is found to have little effect on return periods except when autocorrelation is very high. MC1 and MC2 models are applied to droughts observed in some annual streamflow series, with the result that the MC2 model has a relatively good agreement considering the limited duration of the records.
Changes in Intense Precipitation over the Central United States
Authors: Groisman Pavel Ya. , Knight Richard W. , Karl Thomas R.
Published: September 2011

In examining intense precipitation over the central United States, the authors consider only days with precipitation when the daily total is above 12.7 mm and focus only on these days and multiday events constructed from such consecutive precipitation days. Analyses show that over the central United States, a statistically significant redistribution in the spectra of intense precipitation days/events during the past decades has occurred. Moderately heavy precipitation events (within a 12.7–25.4 mm day−1 range) became less frequent compared to days and events with precipitation totals above 25.4 mm. During the past 31 yr (compared to the 1948–78 period), significant increases occurred in the frequency of “very heavy” (the daily rain events above 76.2 mm) and extreme precipitation events (defined as daily and multiday rain events with totals above 154.9 mm or 6 in.), with up to 40% increases in the frequency of days and multiday extreme rain events. Tropical cyclones associated with extreme precipitation do not significantly contribute to the changes reported in this study. With time, the internal precipitation structure (e.g., mean and maximum hourly precipitation rates within each preselected range of daily or multiday event totals) did not noticeably change. Several possible causes of observed changes in intense precipitation over the central United States are discussed and/or tested.
Counseling for Work and Relationship
Authors: Richardson Mary Sue
Published: September 2011

Counseling for work and relationship is a social constructionist perspective, informed by feminist and social justice values, and responsive to radical changes in contemporary lives, that fosters a shift in vocational psychology from helping people develop careers to helping people construct lives through work and relationship. The first and major proposition of this perspective is a new discourse for describing the construction of lives that specifies four major social contexts through which people construct lives. These social contexts are market work, personal care work, personal relationships, and market work relationships. Additional propositions of the counseling for work and relationship perspective are the centrality of narrative theory for understanding how lives are constructed and agentic action as a critical process in constructing lives. Implications for research, intervention, and training are considered.
On the residual compressive strength of the glass–epoxy tubes subjected to transverse impact loading
Authors: Deniz Mehmet Emin , Karakuzu Ramazan , Sari Murat , Icten Bulent Murat
Published: September 2011

This experimental study discusses the effects of the tube diameter and the impact energy level on the impact and compression after impact behaviors of [±55]3 filament-wound glass/epoxy composite tubes. Four different tube diameters were selected as 50, 75, 100, and 150 mm. The composite tubes were subjected to various impact energy levels, 15, 20, and 25 J, using an instrumented impact testing machine at room temperature. Impacted and nonimpacted samples were subjected to axial compression tests. Results indicated that both specimen diameter and impact energy highly affect the impact response and compression-after impact strength of composite tubes.
Microwave absorbing characteristics of nanocrystalline Fe0.13(CoxNi100−x)0.87 alloy fine fiber–epoxy resin composites
Authors: Shen Xiang-Qian , Song Fu-Zhan , Chen Yun , Meng Xian-Feng , Zhu Yong-Wei
Published: September 2011

The nanocrystalline Fe0.13(Co xNi100− x)0.87 ( x = 30, 50, and 80) alloy fiber 50 wt%–epoxy resin composites were prepared by mixing epoxy resin with the alloy fibers. The electromagnetic parameters of the composites were measured using the coaxial line method and the reflection loss was calculated at a frequency range 1–18 GHz. The results show that the nanocrystalline Fe0.13(Co xNi100− x)0.87 alloy fiber–epoxy resin composites have effective microwave absorption characteristics in radar band, which are mainly influenced by the nanocrystalline alloy composition and the composite thickness. This microwave absorption effect largely arises from the eddy current, ferromagnetic resonance, and dielectric loss in the composite.
Evaluation of fatigue properties of high-performance fibers based on fixed-point bending fatigue test
Authors: Cai Guangming , Wang Xiaoguang , Shi Xianjun , Yu Weidong
Published: September 2011

The main aim of this article is to introduce a bending fatigue testing apparatus and a new fatigue testing method, which can be used to characterize the bending fatigue behavior of flexible materials by setting the following parameters: pre-tension, bending angle, and bending frequency. The Kevlar 49, poly(p-phenylene benzobisoxazole), Nomex, and high-performance polyethylene fibers are chosen to analyze the bending fatigue properties by the new apparatus. The cyclic stress data, number of cycle bending and bending fatigue photos are recorded during the process of the bending fatigue. The curve of the cyclic stress shows that the stress changes in periods during the cyclic bending process. The curve of the cyclic stress is theoretically analyzed. The S–N and the θ−ln N curves indicate that the pre-tension and the bending angle have significant effects on the bending fatigue life. The morphologies obtained from the digital optical apparatus can be used to explain the bending failure mechanisms of high-performance fibers. It is evident that the new bending fatigue testing apparatus is feasible and accurate in measuring and characterizing bending fatigue properties of fibers. The apparatus could effectively describe the bending fatigue lifetime and bending failure mechanisms of high-performance fibers.
Statistical study on non-linear effect of Carbon Nanotube on Mechanical Properties of Epoxy Composite
Authors: Fereidoon A , Rostamiyan Y , Omrani Abdollah , Kordani N , Ganji DD
Published: September 2011

In this manuscript, we generally study the role of functionalized MWCNT in improving mechanical properties of epoxy resins. Also we use ‘central composite design’ model as a statistical experimental design in order to qualitatively investigate the role of various parameters on experiment results. Statistical results show non-linear behavior of effective parameters on experiment results. Also the results of experiments show that, existence of Nano-filler has positive effects on mechanical properties of the Nanocomposites. The results also represent that functionalized Nano-filler with acid and amino agent improve the mechanical properties. Attention to results shows that MWCNT with amino agent is more effective than acid agent in improving the properties.
Infiltration casting and in situ fabrication of tantalum carbide particulate-reinforced iron matrix composites
Authors: Zhong Lisheng , Xu Yunhua , Li Chengchen , Ye Fangxia , Liu Xiaojie , Hojamberdiev Mirabbos
Published: September 2011

Reinforced tantalum carbide particles were synthesized between tantalum wires and graphite in gray cast iron by heat treatment; the effects of different heat treatment times on the phase evolution, microstructure, and micro-hardness of the composites were investigated. The particles obtained were small and square-shaped, 1–2 µm in size, and evenly distributed through the cast iron. The maximum micro-hardness of the composite region was 1832 HV0.1. After 20 min heat treatment, the micro-hardness decreased to approximately 1077 HV0.1, between about four and five times that of the matrix. The resulting composites also presented higher wear resistance compared with unreinforced gray cast iron.
Electrical conductivity of waterborne polyurethane/graphene composites prepared by solution mixing
Authors: Ding J.N. , Fan Y. , Zhao C.X. , Liu Y.B. , Yu C.T. , Yuan N.Y.
Published: September 2011

Hydrothermal method was used to convert graphene oxide to graphene in water. Polyvinylpyrrolidone was added to improve dispersion of graphene and form a stable graphene solution with a high concentration. This stable graphene solution was used to mix with waterborne polyurethane (WPU) to prepare WPU/graphene composites. The electrical conductivity of WPU was greatly improved with incorporation of graphene, and when the filling amount of graphene is 4.0 wt%, the conductivity of the composite reaches 8.30 × 10−4 S cm−1, which is a little higher than that of the composite prepared by in situ method.
Effect of carbon nanofibers content on thermal properties of ceramic nanocomposites
Authors: Borrell A , Rocha VG , Torrecillas R , Fernández A
Published: September 2011

The thermal properties of carbon nanofibers (CNFs)-alumina and CNFs-zirconia nanocomposites densified by spark plasma sintering technique were evaluated. The influence of CNFs content and type of ceramic matrix on thermal conductivity of ceramic-CNFs materials, measured by the laser-flash method, was studied. The effect of CNFs depends noticeably on the ceramic component and thus, an increase of 83% and a decrease of 97% in thermal conductivity at room temperature is observed when 80 vol% of CNFs is added to ZrO2 and Al2O3, respectively. However, even if the thermal conductivity is lower, the efficiency of heat transfer to the environment in CNFs/Al2O3 nanocomposites is better than that corresponding to monolithic alumina. This behavior is due to CNFs arrangement in dense materials. Considering the low electrical resistivity for CNFs/ Al2O3 and CNFs/ ZrO2 materials (10−1–10−2 Ω·cm), these nanocomposites are promising candidates as thermoelectric materials that require low thermal conductivity, but high electrical conductivity.
Polymer nanocomposites reinforced with C60 fullerene: effect of hydroxylation
Authors: Saotome Tsuyoshi , Kokubo Ken , Shirakawa Shogo , Oshima Takumi , Hahn H. Thomas
Published: September 2011

Novel nanocomposite films of polycarbonate (PC) with fullerene derivatives, such as pristine fullerene C60 and polyhydroxylated-fullerenes, C60(OH)12 and C60(OH)36, were prepared. The optical, thermal, and mechanical properties of the composites were measured. Nanocomposite films of poly (vinyl alcohol) (PVA) with C60(OH)36 were prepared as a reference to show how improved dispersion of the nanofiller affects the overall transparency of the composites. Ultraviolet-visible spectroscopy showed that the addition of hydroxylated fullerenes did not affect visible light transmittance of the films significantly in the range of 400–800 nm. Differential scanning calorimetry (DSC) and thermo–gravimetric analysis (TGA) measurements showed the increased thermal stability of PC/C60(OH)12 film as compared to pristine PC film. This phenomenon was explained by the rigid polymer interphase regions formed around C60(OH)12 due to the plausible hydrogen bonding and hydrophobic interaction. On the other hand, the lower thermal stability of PC–C60(OH)36 was assumed to be caused by large agglomeration of the C60(OH)36 particles and the partial hydrolysis of the polycarbonate matrix. Tensile testing of the composites showed reduction in elongation at break and yield tensile strength. These results may be caused by the particle agglomerations which act as the initiation points for cracks.
Investigation of temperature dependency of electrical resistance changes for structural management of graphite/polymer composite
Authors: Takahashi Kosuke , Hahn H. Thomas
Published: September 2011

This article investigates the dependency of electrical resistance on temperature for graphite/polymer composites. The electrical resistance change of a unidirectional laminate is measured with elevated temperature in the fiber, transverse and through-thickness directions. Because of the properties of graphite fibers, the electrical resistance decreases as temperature increases in any direction. The activation energy is calculated from an Arrhenius plot to evaluate the difference among the different directions. The activation energy is the lowest in the fiber direction due to the high electrical conductivity of graphite fibers. Since electric current flows thorough the contacts between neighboring graphite fibers, similar activation energies are required in the transverse and through-thickness directions, indicating transversely isotropic properties. These characteristics will be used to establish the relationship between electrical resistance outputs and structural conditions, and will be eventually applied to an in-service structural management system using addressable conducting network, which is a grid arrangement of conducting lines on a composite panel.
Fabrication and mechanical behaviors of 2D C/SiC–BCx composite at room temperature
Authors: Liu Yongsheng , Cheng Laifei , Zhang Litong , Yang Wenbin , Zhou Shengtian , Zhang Weihua
Published: September 2011

C/SiC composite modified with boron carbide (BC x) matrix (entitled: C/SiC–BC x composite) was fabricated by chemical vapor infiltration (CVI). The densification behavior, microstructure, and mechanical behaviors of C/SiC–BC x composite were investigated. The results indicated that the density increase, corresponding with a decreasing porosity when CVI times increase. The density achieves 2.2 g cm−3 with 5% open porosity ratio. Inner fiber bundle, the matrix is SiC. Among fiber bundles, the matrices are composed with multilayer SiC and BC x. The non-brittle flexural fracture behavior was demonstrated and the flexural strength is 442 MPa. The fracture toughness is 22.84 MPa.m1/2. The non-linear tensile behavior was also demonstrated and the strength is 250 MPa. The compressive curve of sample is linear and the strength is 280 MPa. The in-plane shear behavior is also non-linear and shear strength is 160.9 MPa. The inter-laminar shear behavior is linear and the shear strength is 32.5 MPa. All mechanical behaviors of 2D of the C/SiC–BC x composite have been compared with that of the C/SiC composite.
Development of a new finite element and parametric study for plates with compressible constrained layer damping
Authors: Xie Zhengchao , Shepard W Steve
Published: September 2011

Constrained layer damping (CLD) is widely used in many structures for vibration reduction. It is necessary to model CLD structures precisely. Most existing research studies have modeled the structures as beams, which in many cases is not a sufficient approach. These existing models are based on the assumption that shear deformation in the core layer is the only source of damping in the structure. However, previous research has shown that other types of deformation in the core layer, such as deformations from longitudinal extension and transverse compression, can also be important. To more accurately model CLD, a new plate finite element is developed in this study by assuming that there is shear as well as longitudinal and transverse deformations in the damping layer. This model can be used to better predict the structure’s dynamic characteristics, such as resonant frequencies and modal loss factors. By comparing the new model to experimental results from the open literature, this newly developed plate finite element model is validated. With all three types of damping included in this new approach, it becomes possible to study the impact of various design parameters, such as the damping layer’s thickness. To that end, a parametric study is also conducted using the newly developed finite element for various design parameters.
Self-reinforced nanocomposite by partial dissolution of cellulose microfibrils in ionic liquid
Authors: Shakeri Alireza , Mathew Aji P , Oksman Kristiina
Published: September 2011

All-cellulose nanocomposite films with different ratios of cellulose I and II were produced by partial dissolution of microfibrillated cellulose using ionic liquid and subsequent film casting. The films were isotropic, transparent to visible light, highly crystalline, and contained different amounts of undissolved cellulose I crystallites in a matrix of dissolved cellulose. X-ray diffraction confirmed that cellulose I, i.e., the major polymorphic modification of cellulose in these nanocomposites, is rearranged to cellulose II crystal packing after the partial dissolution. The all-cellulose nanocomposite showed enhanced thermal properties, with thermal degradation temperature increased by 22% compared with thedissolved cellulose. The SEM and AFM studies verified that the nano-sized cellulose crystallites were well dispersed in the matrix. Results from DMA showed that the storage modulus was increased from 270 MPa for the dissolved cellulose to 1104 MPa for the nanocomposite with lower dissolution grade. This indicates that the all-cellulose nanocomposite films contained undissolved cellulose fragments – possibly cellulose I crystallites or aggregates of crystallites in a matrix of regenerated cellulose.
Developmental Factors in Adolescent Child Sexual Offenders
Authors: Dennison Susan , Leclerc Benoit
Published: September 2011

Scholars have studied developmental factors relevant to adult sex offenders. These factors, however, have not been of interest so far in the area of adolescent sexual offenders. Given the paucity of research in this area, this study examines developmental factors that may be relevant in understanding why some offenders become persistent throughout the course of adolescence. The sample consisted of male adolescents convicted of a sexual offense against a child. Compared to nonrepeat sexual offenders ( n = 80), repeat sexual offenders ( n = 27) were characterized by a history of sexual abuse victimization and inappropriate sexual behaviors. However, offenders who had a history of sexual abuse but who did not exhibit inappropriate sexual behaviors were more likely to be classified as repeat sex offenders.
Does the teacher’s pet phenomenon inevitably cause classroom conflict? Comparative viewpoints of three pet-student groups
Authors: Chiu Shao-I , Lee Jiezhi , Liang Tsanglang
Published: September 2011

Although most studies reveal a relationship between the teacher’s pet phenomenon with classroom conflict, it does not necessarily cause classroom conflict. This study confirms the model fit for teacher authority, the existence of the teacher’s pet phenomenon and its relationship to classroom conflict and students’ self-adjustment, as well as testing the different viewpoints of three pet-student groups. Participants in the study comprised 407 5th through 8th grade students from 12 schools in Taiwan. The findings indicate that the estimated model fits the observed data; teacher authority directly affects the teacher’s pet phenomenon and indirectly affects classroom conflict and students’ self-adjustment. Non-pet students, popular-pet students, and unpopular pet students have different viewpoints of the variables. Three sub-models reveal different path effects; the inclusion of popular-pet students does not lead to classroom conflict. Implications for theory, practice, and research are discussed.
An assessment of, and response to, potential cross-contamination routes due to defective appliance water trap seals in building drainage systems
Authors: Gormley M , Swaffield JA , Sleigh PA , Noakes CJ
Published: September 2011

The outbreak of severe acute respiratory syndrome (SARS), centred on Southeast Asia in 2002 and 2003, sparked fears of an uncontrollable pandemic. The outbreak at one housing complex in Hong Kong resulted in a disproportionately large number of cases with 321 people contracting the virus, resulting in 42 fatalities. This outbreak led to an investigation by World Health Organisation, which firmly laid the blame for the spread of the virus in the housing complex on defects in the building drainage and vent system. The mode of viral transmission was identified as due to airborne aerosolised particles from virus-laden excreta emanating from the drainage system. The aerosolised particles were allowed to enter the habitable space through empty water trap seals which are the main protection against such ingress in a building drainage and vent system. This research reports on the defective trap identification system developed to provide a means of testing the seal afforded by the water trap seal inbuildings. This innovative sonar-like technology incorporates a means of identifying compromised water trap seals anywhere in a building in a repeatable, non-destructive manner. While the technology has been effectively validated by a combination of laboratory investigation, site testing and numerical simulation, the rationale for the need to monitor water trap seals is less obvious to professionals operating in this field. This article addresses this issue and presents such a rationale, identifying some of the harmful pathogens which could lead to cross-contamination from person to person via the building drainage system.

Practical applications: The research carried out in this area has highlighted the lack of any real monitoring of water trap seal status in buildings and has put the issue firmly on the agenda for consideration by building owners, operators and regulators, for whom the building drainage and vent system has long been categorised as ‘fit and forget’. The inspiration for this study was the response to the SARS outbreak which began in 2002. The case to monitor this important seal is clearly made and whilst the predicted pandemic of the SARS virus failed to materialise on an extended time frame and the outbreak has largely been consigned to history, it should serve as a constant reminder to professionals in the industry that we ‘fit and forget’ at our peril.