A Student Environment Model: A Measure of Institutional Effectiveness. AIR 1998 Annual Forum Paper.

ERIC Educational Resources Information Center

Morris-Baldwin, Darline

This study traces the development of a student environment model (SEM) at Texas State Technical College (Waco) that is used to assess students' perceptions of their college environment outside the formal classroom, provides baseline data for comparative analyses, establishes goals for student support services, measures program and process…

Method variation in the impact of missing data on response shift detection.

PubMed

Schwartz, Carolyn E; Sajobi, Tolulope T; Verdam, Mathilde G E; Sebille, Veronique; Lix, Lisa M; Guilleux, Alice; Sprangers, Mirjam A G

2015-03-01

Missing data due to attrition or item non-response can result in biased estimates and loss of power in longitudinal quality-of-life (QOL) research. The impact of missing data on response shift (RS) detection is relatively unknown. This overview article synthesizes the findings of three methods tested in this special section regarding the impact of missing data patterns on RS detection in incomplete longitudinal data. The RS detection methods investigated include: (1) Relative importance analysis to detect reprioritization RS in stroke caregivers; (2) Oort's structural equation modeling (SEM) to detect recalibration, reprioritization, and reconceptualization RS in cancer patients; and (3) Rasch-based item-response theory-based (IRT) models as compared to SEM models to detect recalibration and reprioritization RS in hospitalized chronic disease patients. Each method dealt with missing data differently, either with imputation (1), attrition-based multi-group analysis (2), or probabilistic analysis that is robust to missingness due to the specific objectivity property (3). Relative importance analyses were sensitive to the type and amount of missing data and imputation method, with multiple imputation showing the largest RS effects. The attrition-based multi-group SEM revealed differential effects of both the changes in health-related QOL and the occurrence of response shift by attrition stratum, and enabled a more complete interpretation of findings. The IRT RS algorithm found evidence of small recalibration and reprioritization effects in General Health, whereas SEM mostly evidenced small recalibration effects. These differences may be due to differences between the two methods in handling of missing data. Missing data imputation techniques result in different conclusions about the presence of reprioritization RS using the relative importance method, while the attrition-based SEM approach highlighted different recalibration and reprioritization RS effects by attrition group. The IRT analyses detected more recalibration and reprioritization RS effects than SEM, presumably due to IRT's robustness to missing data. Future research should apply simulation techniques in order to make conclusive statements about the impacts of missing data according to the type and amount of RS.

Frame of Reference Model of Self-Concept and Locus of Control: A Cross Gender Study in the United Arab Emirates.

ERIC Educational Resources Information Center

Abu-Hilal, Maher M.

A study tested predictions for I/E (internal external) frame of reference model and extended this model to include locus of control. A sample of upper elementary (n=181) and junior high (n=191) students in the United Arab Emirates participated in the study. Structural equation modeling (SEM) analyses provided support to the external comparison…

A Simulation Study of Threats to Validity in Quasi-Experimental Designs: Interrelationship between Design, Measurement, and Analysis.

PubMed

Holgado-Tello, Fco P; Chacón-Moscoso, Salvador; Sanduvete-Chaves, Susana; Pérez-Gil, José A

2016-01-01

The Campbellian tradition provides a conceptual framework to assess threats to validity. On the other hand, different models of causal analysis have been developed to control estimation biases in different research designs. However, the link between design features, measurement issues, and concrete impact estimation analyses is weak. In order to provide an empirical solution to this problem, we use Structural Equation Modeling (SEM) as a first approximation to operationalize the analytical implications of threats to validity in quasi-experimental designs. Based on the analogies established between the Classical Test Theory (CTT) and causal analysis, we describe an empirical study based on SEM in which range restriction and statistical power have been simulated in two different models: (1) A multistate model in the control condition (pre-test); and (2) A single-trait-multistate model in the control condition (post-test), adding a new mediator latent exogenous (independent) variable that represents a threat to validity. Results show, empirically, how the differences between both the models could be partially or totally attributed to these threats. Therefore, SEM provides a useful tool to analyze the influence of potential threats to validity.

A Simulation Study of Threats to Validity in Quasi-Experimental Designs: Interrelationship between Design, Measurement, and Analysis

PubMed Central

Holgado-Tello, Fco. P.; Chacón-Moscoso, Salvador; Sanduvete-Chaves, Susana; Pérez-Gil, José A.

2016-01-01

The Campbellian tradition provides a conceptual framework to assess threats to validity. On the other hand, different models of causal analysis have been developed to control estimation biases in different research designs. However, the link between design features, measurement issues, and concrete impact estimation analyses is weak. In order to provide an empirical solution to this problem, we use Structural Equation Modeling (SEM) as a first approximation to operationalize the analytical implications of threats to validity in quasi-experimental designs. Based on the analogies established between the Classical Test Theory (CTT) and causal analysis, we describe an empirical study based on SEM in which range restriction and statistical power have been simulated in two different models: (1) A multistate model in the control condition (pre-test); and (2) A single-trait-multistate model in the control condition (post-test), adding a new mediator latent exogenous (independent) variable that represents a threat to validity. Results show, empirically, how the differences between both the models could be partially or totally attributed to these threats. Therefore, SEM provides a useful tool to analyze the influence of potential threats to validity. PMID:27378991

Identification of Some Zeolite Group Minerals by Application of Artificial Neural Network and Decision Tree Algorithm Based on SEM-EDS Data

NASA Astrophysics Data System (ADS)

Akkaş, Efe; Evren Çubukçu, H.; Akin, Lutfiye; Erkut, Volkan; Yurdakul, Yasin; Karayigit, Ali Ihsan

2016-04-01

Identification of zeolite group minerals is complicated due to their similar chemical formulas and habits. Although the morphologies of various zeolite crystals can be recognized under Scanning Electron Microscope (SEM), it is relatively more challenging and problematic process to identify zeolites using their mineral chemical data. SEMs integrated with energy dispersive X-ray spectrometers (EDS) provide fast and reliable chemical data of minerals. However, considering elemental similarities of characteristic chemical formulae of zeolite species (e.g. Clinoptilolite ((Na,K,Ca)2 -3Al3(Al,Si)2Si13O3612H2O) and Erionite ((Na2,K2,Ca)2Al4Si14O36ṡ15H2O)) EDS data alone does not seem to be sufficient for correct identification. Furthermore, the physical properties of the specimen (e.g. roughness, electrical conductivity) and the applied analytical conditions (e.g. accelerating voltage, beam current, spot size) of the SEM-EDS should be uniform in order to obtain reliable elemental results of minerals having high alkali (Na, K) and H2O (approx. %14-18) contents. This study which was funded by The Scientific and Technological Research Council of Turkey (TUBITAK Project No: 113Y439), aims to construct a database as large as possible for various zeolite minerals and to develop a general prediction model for the identification of zeolite minerals using SEM-EDS data. For this purpose, an artificial neural network and rule based decision tree algorithm were employed. Throughout the analyses, a total of 1850 chemical data were collected from four distinct zeolite species, (Clinoptilolite-Heulandite, Erionite, Analcime and Mordenite) observed in various rocks (e.g. coals, pyroclastics). In order to obtain a representative training data set for each minerals, a selection procedure for reference mineral analyses was applied. During the selection procedure, SEM based crystal morphology data, XRD spectra and re-calculated cationic distribution, obtained by EDS have been used for the characterization of the training set. Consequently, for each zeolite species 250 EDS data (as elemental intensities) used for training and 200 ±50 analyses were tested. Finally, two prediction models were developed. The constructed models with various cross-correlation values (r) yielded an average accuracy of >91% for the best predictions using C5.0 Decision Tree algorithm and back propagation artificial neural network. Despite having similar accuracies, the developed models exhibit different prediction behaviors for some zeolite minerals. The results demonstrate that artificial neural network as a nonlinear tool and decision tree algorithm as a rule based prediction model would be employed to provide considerably efficient and reliable identification/classification of some zeolite minerals regardless of their similar elemental compositions. Keywords: mineral identification; zeolites; energy dispersive spectrometry; artificial neural networks; decision tree.

Structural equation modeling of the relationships between pesticide poisoning, depressive symptoms and safety behaviors among Colorado farm residents.

PubMed

Beseler, Cheryl Lynn; Stallones, Lorann

2006-01-01

To use structural equation modeling (SEM) to test the theory that a past pesticide poisoning may act as a mediator in the relationship between depression and safety practices. Depression has been associated with pesticide poisoning and was more strongly associated with safety behaviors than workload, social support or health status of farm residents in a previously published report. A cross-sectional survey of farmers and their spouses was conducted in eight counties in northeastern Colorado. Depressive symptoms were assessed using the Center for Epidemiologic Studies-Depression (CES-D) scale. Exploratory and confirmatory factor analyses were used to identify symptoms most correlated with risk factors for depression and safety practices. SEM was used to examine theoretical causal models of the relationship between depression and poor health, financial difficulties, a history of pesticide poisoning, and safety practices. Exploratory factor analysis identified three factors in the CES-D scale. The SEM showed that poor health, financial difficulties and a history of pesticide poisoning significantly explained the depressive symptoms. Models with an excellent fit for the safety behaviors resulted when modeling the probability that the pesticide poisoning preceded depression, but no fit was possible when reversing the direction and modeling depression preceding pesticide poisoning. Specific depressive symptoms appeared to be significantly associated with primarily animal handling and farm machinery. The order of events, based on SEM results, was a pesticide poisoning preceding depressed mood in relation to safety behaviors.

Failure analysis of broken pedicle screws on spinal instrumentation.

PubMed

Chen, Chen-Sheng; Chen, Wen-Jer; Cheng, Cheng-Kung; Jao, Shyh-Hua Eric; Chueh, Shan-Chang; Wang, Chang-Chih

2005-07-01

Revised spinal surgery is needed when there is a broken pedicle screw in the patient. This study investigated the pedicle screw breakage by conducting retrieval analyses of broken pedicle screws from 16 patients clinically and by performing stress analyses in the posterolateral fusion computationally using finite element (FE) models. Fracture surface of screws was studied by scanning electron microscope (SEM). The FE model of the posterolateral fusion with the screw showed that screws on the caudal side had larger axial stress than those on the cephalic side, supporting the clinical findings that 75% of the patients had the screw breakage on the caudal side. SEM fractography showed that all broken screws exhibited beach marks or striations on the fractured surface, indicating fatigue failure. Screws of patients with spinal fracture showed fatigue striations and final ductile fracture around the edge. Among the 16 patients who had broken pedicle screws 69% of them achieved bone union in the bone graft, showing that bone union in the bone graft did not warrant the prevention of screw breakage.

Replication and extension of a hierarchical model of social anxiety and depression: fear of positive evaluation as a key unique factor in social anxiety.

PubMed

Weeks, Justin W

2015-01-01

Wang, Hsu, Chiu, and Liang (2012, Journal of Anxiety Disorders, 26, 215-224) recently proposed a hierarchical model of social interaction anxiety and depression to account for both the commonalities and distinctions between these conditions. In the present paper, this model was extended to more broadly encompass the symptoms of social anxiety disorder, and replicated in a large unselected, undergraduate sample (n = 585). Structural equation modeling (SEM) and hierarchical regression analyses were employed. Negative affect and positive affect were conceptualized as general factors shared by social anxiety and depression; fear of negative evaluation (FNE) and disqualification of positive social outcomes were operationalized as specific factors, and fear of positive evaluation (FPE) was operationalized as a factor unique to social anxiety. This extended hierarchical model explicates structural relationships among these factors, in which the higher-level, general factors (i.e., high negative affect and low positive affect) represent vulnerability markers of both social anxiety and depression, and the lower-level factors (i.e., FNE, disqualification of positive social outcomes, and FPE) are the dimensions of specific cognitive features. Results from SEM and hierarchical regression analyses converged in support of the extended model. FPE is further supported as a key symptom that differentiates social anxiety from depression.

Posttraumatic stress symptoms and the diathesis-stress model of chronic pain and disability in patients undergoing major surgery.

PubMed

Martin, Andrea L; Halket, Eileen; Asmundson, Gordon J G; Flora, David B; Katz, Joel

2010-01-01

To (1) use structural equation modeling (SEM) to examine relationships proposed in Turk's diathesis-stress model of chronic pain and disability as well as (2) investigate what role, if any, posttraumatic stress symptoms (PTSS) play in predicting pain disability, relative to some of the other factors in the model. The study sample consisted of 208 patients scheduled for general surgery, 21 to 60 years of age (mean age=47.18 y, SD=9.72 y), who reported experiencing persistent pain for an average of 5.56 years (SD=7.90 y). At their preadmission hospital visit, patients completed the Anxiety Sensitivity Index, Pain Catastrophizing Scale, Pain Anxiety Symptoms Scale-20, Pain Disability Index, posttraumatic stress disorder Checklist, and rated the average intensity of their pain (0 to 10 numeric rating scale). SEM was used to test a model of chronic pain disability and to explore potential relationships between PTSS and factors in the diathesis-stress model. SEM results provided support for a model in which anxiety sensitivity predicted fear of pain and catastrophizing, fear of pain predicted escape/avoidance, and escape/avoidance predicted pain disability. Results also provided support for a feedback loop between disability and fear of pain. SEM analyses provided preliminary support for the inclusion of PTSS in the diathesis-stress model, with PTSS accounting for a significant proportion of the variance in pain disability. Results provide empirical support for aspects of Turk's diathesis-stress model in a sample of patients with persistent pain. Findings also offer preliminary support for the role of PTSS in fear-avoidance models of chronic pain.

Quantified Choice of Root-Mean-Square Errors of Approximation for Evaluation and Power Analysis of Small Differences between Structural Equation Models

ERIC Educational Resources Information Center

Li, Libo; Bentler, Peter M.

2011-01-01

MacCallum, Browne, and Cai (2006) proposed a new framework for evaluation and power analysis of small differences between nested structural equation models (SEMs). In their framework, the null and alternative hypotheses for testing a small difference in fit and its related power analyses were defined by some chosen root-mean-square error of…

Burnout and connectedness in the job demands-resources model: studying palliative care volunteers and their families.

PubMed

Huynh, Jasmine-Yan; Winefield, Anthony H; Xanthopoulou, Despoina; Metzer, Jacques C

2012-09-01

This study examined the role of burnout and connectedness in the job demands-resources (JD-R) model among palliative care volunteers. It was hypothesized that (a) exhaustion mediates the relationship between demands and depression, and between demands and retention; (b) cynicism mediates the relationship between resources and retention; and (c) connectedness mediates the relationship between resources and retention. Hypotheses were tested in 2 separate analyses: structural equation modeling (SEM) and path analyses. The first was based on volunteer self-reports (N = 204), while the second analysis concerned matched data from volunteers and their family members (N = 99). While strong support was found for cynicism and connectedness as mediators in both types of analyses, this was not altogether the case for exhaustion. Implications of these findings for the JD-R model and volunteer organizations are discussed.

Differential Ability Scales-II Prediction of Reading Performance: Global Scores Are Not Enough

ERIC Educational Resources Information Center

Elliott, Colin D.; Hale, James B.; Fiorello, Catherine A.; Dorvil, Cledicianne; Moldovan, Jaime

2010-01-01

This study investigated the effects of broad cognitive abilities derived from the Cattell-Horn-Carroll (CHC) taxonomy, together with the effect of the general factor ("g"), on Wechsler Individual Achievement Test, Second Edition (WIAT-II) reading achievement. Structural equation modeling (SEM) and commonality analyses were applied to the…

SEM and TEM Analyses of Minerals Xifengite, Gupeiite, Fe2Si (Hapkeite?), Titanium Carbide (TiC) and Cubic Moissanite (SiC) from the Subsoil in the Alpine Foreland: Are they Cosmochemical?

NASA Astrophysics Data System (ADS)

Hiltl, M.; Bauer, F.; Ernstson, K.; Mayer, W.; Neumair, A.; Rappenglück, M. A.

2011-03-01

SEM and TEM analyses of millimeter- to centimeter-sized particles from Holocene soils reveal a multi-stoichiometric iron silicide matrix containing purest crystals of titanium carbide and cubic moissanite. A cosmochemical origin is suggested.

Reliability of four models for clinical gait analysis.

PubMed

Kainz, Hans; Graham, David; Edwards, Julie; Walsh, Henry P J; Maine, Sheanna; Boyd, Roslyn N; Lloyd, David G; Modenese, Luca; Carty, Christopher P

2017-05-01

Three-dimensional gait analysis (3DGA) has become a common clinical tool for treatment planning in children with cerebral palsy (CP). Many clinical gait laboratories use the conventional gait analysis model (e.g. Plug-in-Gait model), which uses Direct Kinematics (DK) for joint kinematic calculations, whereas, musculoskeletal models, mainly used for research, use Inverse Kinematics (IK). Musculoskeletal IK models have the advantage of enabling additional analyses which might improve the clinical decision-making in children with CP. Before any new model can be used in a clinical setting, its reliability has to be evaluated and compared to a commonly used clinical gait model (e.g. Plug-in-Gait model) which was the purpose of this study. Two testers performed 3DGA in eleven CP and seven typically developing participants on two occasions. Intra- and inter-tester standard deviations (SD) and standard error of measurement (SEM) were used to compare the reliability of two DK models (Plug-in-Gait and a six degrees-of-freedom model solved using Vicon software) and two IK models (two modifications of 'gait2392' solved using OpenSim). All models showed good reliability (mean SEM of 3.0° over all analysed models and joint angles). Variations in joint kinetics were less in typically developed than in CP participants. The modified 'gait2392' model which included all the joint rotations commonly reported in clinical 3DGA, showed reasonable reliable joint kinematic and kinetic estimates, and allows additional musculoskeletal analysis on surgically adjustable parameters, e.g. muscle-tendon lengths, and, therefore, is a suitable model for clinical gait analysis. Copyright © 2017. Published by Elsevier B.V.

Randomized trial in malignant biliary obstruction: Plastic vs partially covered metal stents

PubMed Central

Moses, Peter L; AlNaamani, Khalid M; Barkun, Alan N; Gordon, Stuart R; Mitty, Roger D; Branch, M Stanley; Kowalski, Thomas E; Martel, Myriam; Adam, Viviane

2013-01-01

AIM: To compare efficacy and complications of partially covered self-expandable metal stent (pcSEMS) to plastic stent (PS) in patients treated for malignant, infrahilar biliary obstruction. METHODS: Multicenter prospective randomized clinical trial with treatment allocation to a pcWallstent® (SEMS) or a 10 French PS. Palliative patients aged ≥ 18, for infrahilar malignant biliary obstruction and a Karnofsky performance scale index > 60% from 6 participating North American university centers. Primary endpoint was time to stent failure, with secondary outcomes of death, adverse events, Karnofsky performance score and short-form-36 scale administered on a three-monthly basis for up to 2 years. Survival analyses were performed for stent failure and death, with Cox proportional hazards regression models to determine significant predictive characteristics. RESULTS: Eighty-five patients were accrued over 37 mo, 42 were randomized to the SEMS group and 83 patients were available for analyses. Time to stent failure was 385.3 ± 52.5 d in the SEMS and 153.3 ± 19.8 d in the PS group, P = 0.006. Time to death did not differ between groups (192.3 ± 23.4 d for SEMS vs 211.5 ± 28.0 d for PS, P = 0.70). The only significant predictor was treatment allocation, relating to the time to stent failure (P = 0.01). Amongst other measured outcomes, only cholangitis differed, being more common in the PS group (4.9% vs 24.5%, P = 0.029). The small number of patients in follow-up limits longitudinal assessments of performance and quality of life. From an initially planned 120 patients, only 85 patients were recruited. CONCLUSION: Partially covered SEMS result in a longer duration till stent failure without increased complication rates, yet without accompanying measurable benefits in survival, performance, or quality of life. PMID:24379581

Finite Element Model Optimization of the FalconSAT-5 Structural Engineering Model

DTIC Science & Technology

2009-03-01

for coupled loads analyses. To develop the FE tuning process, this research focuses on the United States Air Force Academy (USAFA) FalconSAT-5 SEM II...Kirtland Air Force Base (KAFB) were sufficient for design engineers to ensure compliance with launch loads. However, for the coupled loads analysis...OF THE AIR FORCE AIR UNIVERSITY AIR FORCE INSTITUTE OF TECHNOLOGY Wright-Patterson Air Force Base, Ohio APPROVED FOR PUBLIC RELEASE; DISTRIBUTION

CD-SEM real time bias correction using reference metrology based modeling

NASA Astrophysics Data System (ADS)

Ukraintsev, V.; Banke, W.; Zagorodnev, G.; Archie, C.; Rana, N.; Pavlovsky, V.; Smirnov, V.; Briginas, I.; Katnani, A.; Vaid, A.

2018-03-01

Accuracy of patterning impacts yield, IC performance and technology time to market. Accuracy of patterning relies on optical proximity correction (OPC) models built using CD-SEM inputs and intra die critical dimension (CD) control based on CD-SEM. Sub-nanometer measurement uncertainty (MU) of CD-SEM is required for current technologies. Reported design and process related bias variation of CD-SEM is in the range of several nanometers. Reference metrology and numerical modeling are used to correct SEM. Both methods are slow to be used for real time bias correction. We report on real time CD-SEM bias correction using empirical models based on reference metrology (RM) data. Significant amount of currently untapped information (sidewall angle, corner rounding, etc.) is obtainable from SEM waveforms. Using additional RM information provided for specific technology (design rules, materials, processes) CD extraction algorithms can be pre-built and then used in real time for accurate CD extraction from regular CD-SEM images. The art and challenge of SEM modeling is in finding robust correlation between SEM waveform features and bias of CD-SEM as well as in minimizing RM inputs needed to create accurate (within the design and process space) model. The new approach was applied to improve CD-SEM accuracy of 45 nm GATE and 32 nm MET1 OPC 1D models. In both cases MU of the state of the art CD-SEM has been improved by 3x and reduced to a nanometer level. Similar approach can be applied to 2D (end of line, contours, etc.) and 3D (sidewall angle, corner rounding, etc.) cases.

Mechanisms of Association between Paternal Alcoholism and Abuse of Alcohol and Other Illicit Drugs among Adolescents

ERIC Educational Resources Information Center

Peleg-Oren, Neta; Hospital, Michelle; Morris, Staci Leon; Wagner, Eric F.

2013-01-01

The current study examines the effect of paternal alcohol problems on adolescent use of alcohol and other illicit drugs as a function of maternal communication, as well as adolescent social and coping skills (N = 145). Structural equation modeling (SEM) analyses indicated that adolescents with a paternal history of alcohol problems reported higher…

Structural Equation Modeling: A Framework for Ocular and Other Medical Sciences Research

PubMed Central

Christ, Sharon L.; Lee, David J.; Lam, Byron L.; Diane, Zheng D.

2017-01-01

Structural equation modeling (SEM) is a modeling framework that encompasses many types of statistical models and can accommodate a variety of estimation and testing methods. SEM has been used primarily in social sciences but is increasingly used in epidemiology, public health, and the medical sciences. SEM provides many advantages for the analysis of survey and clinical data, including the ability to model latent constructs that may not be directly observable. Another major feature is simultaneous estimation of parameters in systems of equations that may include mediated relationships, correlated dependent variables, and in some instances feedback relationships. SEM allows for the specification of theoretically holistic models because multiple and varied relationships may be estimated together in the same model. SEM has recently expanded by adding generalized linear modeling capabilities that include the simultaneous estimation of parameters of different functional form for outcomes with different distributions in the same model. Therefore, mortality modeling and other relevant health outcomes may be evaluated. Random effects estimation using latent variables has been advanced in the SEM literature and software. In addition, SEM software has increased estimation options. Therefore, modern SEM is quite general and includes model types frequently used by health researchers, including generalized linear modeling, mixed effects linear modeling, and population average modeling. This article does not present any new information. It is meant as an introduction to SEM and its uses in ocular and other health research. PMID:24467557

Does exercise habit strength moderate the relationship between emotional distress and short-term memory in Malaysian primary school children?

PubMed

Zainol, Nurul Ain; Hashim, Hairul Anuar

2015-01-01

We examined the moderating effects of exercise habit strength on the relationship between emotional distress and short-term memory in primary school children. The sample consisted of 165 primary school students (10-12 years old). Participants completed measures of emotional distress, exercise habit strength, and the Digit Span Test. Mid-year exam results were used as an indicator of academic performance. Structural equation modelling (SEM) was used to analyse the data. The results of SEM revealed an acceptable fit for the hypothesised model. Exercise habit was positively associated with short-term memory, and better short-term memory was associated with better academic performance. However, although an inverse relationship was found between emotional distress and short-term memory, a positive association was found between exercise habit strength and emotional distress. The findings indicate that exercise habit is positively associated with cognitive ability and mediates the negative effect of distress.

Examining the Link between Patient Satisfaction and Adherence to HIV Care: A Structural Equation Model

PubMed Central

Dang, Bich N.; Westbrook, Robert A.; Black, William C.; Rodriguez-Barradas, Maria C.; Giordano, Thomas P.

2013-01-01

Introduction Analogous to the business model of customer satisfaction and retention, patient satisfaction could serve as an innovative, patient-centered focus for increasing retention in HIV care and adherence to HAART, and ultimately HIV suppression. Objective To test, through structural equation modeling (SEM), a model of HIV suppression in which patient satisfaction influences HIV suppression indirectly through retention in HIV care and adherence to HAART. Methods We conducted a cross-sectional study of adults receiving HIV care at two clinics in Texas. Patient satisfaction was based on two validated items, one adapted from the Consumer Assessment of Healthcare Providers and Systems survey (“Would you recommend this clinic to other patients with HIV?) and one adapted from the Delighted-Terrible Scale, (“Overall, how do you feel about the care you got at this clinic in the last 12 months?”). A validated, single-item question measured adherence to HAART over the past 4 weeks. Retention in HIV care was based on visit constancy in the year prior to the survey. HIV suppression was defined as plasma HIV RNA <48 copies/mL at the time of the survey. We used SEM to test hypothesized relationships. Results The analyses included 489 patients (94% of eligible patients). The patient satisfaction score had a mean of 8.5 (median 9.2) on a 0- to 10- point scale. A total of 46% reported “excellent” adherence, 76% had adequate retention, and 70% had HIV suppression. In SEM analyses, patient satisfaction with care influences retention in HIV care and adherence to HAART, which in turn serve as key determinants of HIV suppression (all p<.0001). Conclusions Patient satisfaction may have direct effects on retention in HIV care and adherence to HAART. Interventions to improve the care experience, without necessarily targeting objective clinical performance measures, could serve as an innovative method for optimizing HIV outcomes. PMID:23382948

Structural Equation Model Trees

ERIC Educational Resources Information Center

Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman

2013-01-01

In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree…

Evaluation of an Approximate Method for Synthesizing Covariance Matrices for Use in Meta-Analytic SEM

ERIC Educational Resources Information Center

Beretvas, S. Natasha; Furlow, Carolyn F.

2006-01-01

Meta-analytic structural equation modeling (MA-SEM) is increasingly being used to assess model-fit for variables' interrelations synthesized across studies. MA-SEM researchers have analyzed synthesized correlation matrices using structural equation modeling (SEM) estimation that is designed for covariance matrices. This can produce incorrect…

Structural Equation Model Trees

PubMed Central

Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman

2015-01-01

In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree structures that separate a data set recursively into subsets with significantly different parameter estimates in a SEM. SEM Trees provide means for finding covariates and covariate interactions that predict differences in structural parameters in observed as well as in latent space and facilitate theory-guided exploration of empirical data. We describe the methodology, discuss theoretical and practical implications, and demonstrate applications to a factor model and a linear growth curve model. PMID:22984789

Stochastic epigenetic mutations (DNA methylation) increase exponentially in human aging and correlate with X chromosome inactivation skewing in females.

PubMed

Gentilini, Davide; Garagnani, Paolo; Pisoni, Serena; Bacalini, Maria Giulia; Calzari, Luciano; Mari, Daniela; Vitale, Giovanni; Franceschi, Claudio; Di Blasio, Anna Maria

2015-08-01

In this study we applied a new analytical strategy to investigate the relations between stochastic epigenetic mutations (SEMs) and aging. We analysed methylation levels through the Infinium HumanMethylation27 and HumanMethylation450 BeadChips in a population of 178 subjects ranging from 3 to 106 years. For each CpG probe, epimutated subjects were identified as the extreme outliers with methylation level exceeding three times interquartile ranges the first quartile (Q1-(3 x IQR)) or the third quartile (Q3+(3 x IQR)). We demonstrated that the number of SEMs was low in childhood and increased exponentially during aging. Using the HUMARA method, skewing of X chromosome inactivation (XCI) was evaluated in heterozygotes women. Multivariate analysis indicated a significant correlation between log(SEMs) and degree of XCI skewing after adjustment for age (β = 0.41; confidence interval: 0.14, 0.68; p-value = 0.0053). The PATH analysis tested the complete model containing the variables: skewing of XCI, age, log(SEMs) and overall CpG methylation. After adjusting for the number of epimutations we failed to confirm the well reported correlation between skewing of XCI and aging. This evidence might suggest that the known correlation between XCI skewing and aging could not be a direct association but mediated by the number of SEMs.

A structural equation modelling approach to explore the role of B vitamins and immune markers in lung cancer risk.

PubMed

Baltar, Valéria Troncoso; Xun, Wei W; Johansson, Mattias; Ferrari, Pietro; Chuang, Shu-Chun; Relton, Caroline; Ueland, Per Magne; Midttun, Øivind; Slimani, Nadia; Jenab, Mazda; Clavel-Chapelon, Françoise; Boutron-Ruault, Marie-Christine; Fagherazzi, Guy; Kaaks, Rudolf; Rohrmann, Sabine; Boeing, Heiner; Weikert, Cornelia; Bueno-de-Mesquita, Bas; Boshuizen, Hendriek; van Gils, Carla H; Onland-Moret, N Charlotte; Agudo, Antonio; Barricarte, Aurelio; Navarro, Carmen; Rodríguez, Laudina; Castaño, José Maria Huerta; Larrañaga, Nerea; Khaw, Kay-Tee; Wareham, Nick; Allen, Naomi E; Crowe, Francesca; Gallo, Valentina; Norat, Teresa; Krogh, Vittorio; Masala, Giovanna; Panico, Salvatore; Sacerdote, Carlotta; Tumino, Rosario; Trichopoulou, Antonia; Lagiou, Pagona; Trichopoulos, Dimitrios; Rasmuson, Torgny; Hallmans, Göran; Roswall, Nina; Tjønneland, Anne; Riboli, Elio; Brennan, Paul; Vineis, Paolo

2013-08-01

The one-carbon metabolism (OCM) is considered key in maintaining DNA integrity and regulating gene expression, and may be involved in the process of carcinogenesis. Several B-vitamins and amino acids have been implicated in lung cancer risk, via the OCM directly as well as immune system activation. However it is unclear whether these factors act independently or through complex mechanisms. The current study applies structural equations modelling (SEM) to further disentangle the mechanisms involved in lung carcinogenesis. SEM allows simultaneous estimation of linear relations where a variable can be the outcome in one equation and the predictor in another, as well as allowing estimation using latent variables (factors estimated by correlation matrix). A large number of biomarkers have been analysed from 891 lung cancer cases and 1,747 controls nested within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Four putative mechanisms in the OCM and immunity were investigated in relation to lung cancer risk: methionine-homocysteine metabolism, folate cycle, transsulfuration, and mechanisms involved in inflammation and immune activation, all adjusted for tobacco exposure. The hypothesized SEM model confirmed a direct and protective effect for factors representing methionine-homocysteine metabolism (p = 0.020) and immune activation (p = 0.021), and an indirect protective effect of folate cycle (p = 0.019), after adjustment for tobacco smoking. In conclusion, our results show that in the investigation of the involvement of the OCM, the folate cycle and immune system in lung carcinogenesis, it is important to consider complex pathways (by applying SEM) rather than the effects of single vitamins or nutrients (e.g. using traditional multiple regression). In our study SEM were able to suggest a greater role of the methionine-homocysteine metabolism and immune activation over other potential mechanisms.

The SEM Risk Behavior (SRB) Model: A New Conceptual Model of how Pornography Influences the Sexual Intentions and HIV Risk Behavior of MSM.

PubMed

Wilkerson, J Michael; Iantaffi, Alex; Smolenski, Derek J; Brady, Sonya S; Horvath, Keith J; Grey, Jeremy A; Rosser, B R Simon

2012-01-01

While the effects of sexually explicit media (SEM) on heterosexuals' sexual intentions and behaviors have been studied, little is known about the consumption and possible influence of SEM among men who have sex with men (MSM). Importantly, conceptual models of how Internet-based SEM influences behavior are lacking. Seventy-nine MSM participated in online focus groups about their SEM viewing preferences and sexual behavior. Twenty-three participants reported recent exposure to a new behavior via SEM. Whether participants modified their sexual intentions and/or engaged in the new behavior depended on three factors: arousal when imagining the behavior, pleasure when attempting the behavior, and trust between sex partners. Based on MSM's experience, we advance a model of how viewing a new sexual behavior in SEM influences sexual intentions and behaviors. The model includes five paths. Three paths result in the maintenance of sexual intentions and behaviors. One path results in a modification of sexual intentions while maintaining previous sexual behaviors, and one path results in a modification of both sexual intentions and behaviors. With this model, researchers have a framework to test associations between SEM consumption and sexual intentions and behavior, and public health programs have a framework to conceptualize SEM-based HIV/STI prevention programs.

An overview of structural equation modeling: its beginnings, historical development, usefulness and controversies in the social sciences.

PubMed

Tarka, Piotr

2018-01-01

This paper is a tribute to researchers who have significantly contributed to improving and advancing structural equation modeling (SEM). It is, therefore, a brief overview of SEM and presents its beginnings, historical development, its usefulness in the social sciences and the statistical and philosophical (theoretical) controversies which have often appeared in the literature pertaining to SEM. Having described the essence of SEM in the context of causal analysis, the author discusses the years of the development of structural modeling as the consequence of many researchers' systematically growing needs (in particular in the social sciences) who strove to effectively understand the structure and interactions of latent phenomena. The early beginnings of SEM models were related to the work of Spearman and Wright, and to that of other prominent researchers who contributed to SEM development. The importance and predominance of theoretical assumptions over technical issues for the successful construction of SEM models are also described. Then, controversies regarding the use of SEM in the social sciences are presented. Finally, the opportunities and threats of this type of analytical strategy as well as selected areas of SEM applications in the social sciences are discussed.

Pain and chronic mild traumatic brain injury in the US military population: a Chronic Effects of Neurotrauma Consortium study.

PubMed

Hoot, Michelle R; Levin, Harvey S; Smith, Austin N; Goldberg, Gary; Wilde, Elisabeth A; Walker, William C; Eapen, Blessen C; Nolen, T; Pugh, N L

2018-06-08

To describe the association between mild traumatic brain injury (mTBI) and pain intensity and pain interference outcomes while accounting for potential confounders and mediators including environmental factors and comorbidities in a cohort of US Veterans of the Iraq and Afghanistan wars. Cross-sectional snapshot of baseline data from a prospective, longitudinal study. Effects of mTBI on pain intensity and pain interference were compared between participants with or without mTBI exposure. Data were analysed using covariate-adjusted regression analyses as well as structural equation modelling (SEM) methods to assess the robustness of findings across different modelling assumptions. As results of the two approaches were consistent with respect to the overall association between mTBI exposure and pain, the results focus primarily on the SEM findings. The mTBI exposed group reported significantly greater indices of post-traumatic stress disorder (PTSD), depression, anxiety and sleep disturbance. After accounting for other factors, mTBI exposure was significantly, but indirectly associated with the pain interference and pain intensity outcomes. mTBI is strongly associated with pain intensity and pain interference in this sample. However, the effect appears to be mediated by other common mTBI comorbidities: PTSD, depression, anxiety and sleep disturbance.

The development of comparative bias index

NASA Astrophysics Data System (ADS)

Aimran, Ahmad Nazim; Ahmad, Sabri; Afthanorhan, Asyraf; Awang, Zainudin

2017-08-01

Structural Equation Modeling (SEM) is a second generation statistical analysis techniques developed for analyzing the inter-relationships among multiple variables in a model simultaneously. There are two most common used methods in SEM namely Covariance-Based Structural Equation Modeling (CB-SEM) and Partial Least Square Path Modeling (PLS-PM). There have been continuous debates among researchers in the use of PLS-PM over CB-SEM. While there is few studies were conducted to test the performance of CB-SEM and PLS-PM bias in estimating simulation data. This study intends to patch this problem by a) developing the Comparative Bias Index and b) testing the performance of CB-SEM and PLS-PM using developed index. Based on balanced experimental design, two multivariate normal simulation data with of distinct specifications of size 50, 100, 200 and 500 are generated and analyzed using CB-SEM and PLS-PM.

The role of workaholism in the job demands-resources model.

PubMed

Molino, Monica; Bakker, Arnold B; Ghislieri, Chiara

2016-07-01

The present study tries to gain more insight in workaholism by investigating its antecedents and consequences using the job demands-resources model. We hypothesized that job demands would be positively related to workaholism, particularly when job resources are low. In addition, we hypothesized that workaholism would be positively related to negative outcomes in three important life domains: health, family, and work. The research involved 617 Italian workers (employees and self-employed). To test the hypotheses we applied structural equation modeling (SEM) and moderated structural equation modeling (MSEM) using Mplus 6. The results of SEM showed a good model where workload, cognitive demands, emotional demands, and customer-related social stressors were positively related to workaholism and work-family conflict (WFC) (partial mediation). Additionally, workaholism was indirectly related to exhaustion and intentions to change jobs through WFC. Moreover, MSEM analyses confirmed that job resources (job security and opportunities for development) buffered the relationship between job demands and workaholism. Particularly, the interaction effects were statistically significant in five out of eight combinations. These findings suggest that workaholism is a function of a suboptimal work environment and predicts unfavorable employee outcomes. We discuss the theoretical and practical implications of these findings.

The SEM Risk Behavior (SRB) Model: A New Conceptual Model of how Pornography Influences the Sexual Intentions and HIV Risk Behavior of MSM

PubMed Central

Wilkerson, J. Michael; Iantaffi, Alex; Smolenski, Derek J.; Brady, Sonya S.; Horvath, Keith J.; Grey, Jeremy A.; Rosser, B. R. Simon

2012-01-01

While the effects of sexually explicit media (SEM) on heterosexuals’ sexual intentions and behaviors have been studied, little is known about the consumption and possible influence of SEM among men who have sex with men (MSM). Importantly, conceptual models of how Internet-based SEM influences behavior are lacking. Seventy-nine MSM participated in online focus groups about their SEM viewing preferences and sexual behavior. Twenty-three participants reported recent exposure to a new behavior via SEM. Whether participants modified their sexual intentions and/or engaged in the new behavior depended on three factors: arousal when imagining the behavior, pleasure when attempting the behavior, and trust between sex partners. Based on MSM’s experience, we advance a model of how viewing a new sexual behavior in SEM influences sexual intentions and behaviors. The model includes five paths. Three paths result in the maintenance of sexual intentions and behaviors. One path results in a modification of sexual intentions while maintaining previous sexual behaviors, and one path results in a modification of both sexual intentions and behaviors. With this model, researchers have a framework to test associations between SEM consumption and sexual intentions and behavior, and public health programs have a framework to conceptualize SEM-based HIV/STI prevention programs. PMID:23185126

Multiple-Group Analysis Using the sem Package in the R System

ERIC Educational Resources Information Center

Evermann, Joerg

2010-01-01

Multiple-group analysis in covariance-based structural equation modeling (SEM) is an important technique to ensure the invariance of latent construct measurements and the validity of theoretical models across different subpopulations. However, not all SEM software packages provide multiple-group analysis capabilities. The sem package for the R…

Implementing Restricted Maximum Likelihood Estimation in Structural Equation Models

ERIC Educational Resources Information Center

Cheung, Mike W.-L.

2013-01-01

Structural equation modeling (SEM) is now a generic modeling framework for many multivariate techniques applied in the social and behavioral sciences. Many statistical models can be considered either as special cases of SEM or as part of the latent variable modeling framework. One popular extension is the use of SEM to conduct linear mixed-effects…

Social goals, social behavior, and social status in middle childhood.

PubMed

Rodkin, Philip C; Ryan, Allison M; Jamison, Rhonda; Wilson, Travis

2013-06-01

This study examines motivational precursors of social status and the applicability of a dual-component model of social competence to middle childhood. Concurrent and longitudinal relationships between self-reported social goals (social development, demonstration-approach, demonstration-avoid goal orientations), teacher-rated prosocial and aggressive behavior, and peer nominations of social status (preference, popularity) were examined over the course of an academic year among 980 3rd- to 5th-grade children. Findings support dual-component expectations. Confirmatory factor analyses verified the expected 3-factor structure of social goals and 2-factor structure of social status. Structural equation modeling (SEM) found that (a) social development goals were associated with prosocial behavior and increased preference, and (b) demonstration-approach goals were associated with aggressive behavior and increased popularity. Demonstration-avoid goals were associated with a popularity decrease. SEMs were invariant across grade, gender, and ethnicity. Discussion concerns the potential risks of high social status, extensions to the dual-component model, and the generality of an achievement goal approach to child social development. PsycINFO Database Record (c) 2013 APA, all rights reserved

Spectral-element Method for 3D Marine Controlled-source EM Modeling

NASA Astrophysics Data System (ADS)

Liu, L.; Yin, C.; Zhang, B., Sr.; Liu, Y.; Qiu, C.; Huang, X.; Zhu, J.

2017-12-01

As one of the predrill reservoir appraisal methods, marine controlled-source EM (MCSEM) has been widely used in mapping oil reservoirs to reduce risk of deep water exploration. With the technical development of MCSEM, the need for improved forward modeling tools has become evident. We introduce in this paper spectral element method (SEM) for 3D MCSEM modeling. It combines the flexibility of finite-element and high accuracy of spectral method. We use Galerkin weighted residual method to discretize the vector Helmholtz equation, where the curl-conforming Gauss-Lobatto-Chebyshev (GLC) polynomials are chosen as vector basis functions. As a kind of high-order complete orthogonal polynomials, the GLC have the characteristic of exponential convergence. This helps derive the matrix elements analytically and improves the modeling accuracy. Numerical 1D models using SEM with different orders show that SEM method delivers accurate results. With increasing SEM orders, the modeling accuracy improves largely. Further we compare our SEM with finite-difference (FD) method for a 3D reservoir model (Figure 1). The results show that SEM method is more effective than FD method. Only when the mesh is fine enough, can FD achieve the same accuracy of SEM. Therefore, to obtain the same precision, SEM greatly reduces the degrees of freedom and cost. Numerical experiments with different models (not shown here) demonstrate that SEM is an efficient and effective tool for MSCEM modeling that has significant advantages over traditional numerical methods.This research is supported by Key Program of National Natural Science Foundation of China (41530320), China Natural Science Foundation for Young Scientists (41404093), and Key National Research Project of China (2016YFC0303100, 2017YFC0601900).

The influence of maternal psychopathology on ratings of child psychiatric symptoms: an SEM analysis on cross-informant agreement.

PubMed

Müller, Jörg M; Achtergarde, Sandra; Furniss, Tilman

2011-05-01

The distorting influence of maternal depression on the ratings of child behaviour is known as the depression-distortion hypothesis. This study investigated the depression-distortion hypothesis in a clinical sample of child psychiatric preschool children and extended the depression-distortion hypothesis to maternal psychopathology-distortion hypothesis in general. Subjects were 124 children, who were referred for treatment in a Child Psychiatric Family Day Hospital for preschool children, and their parents. Children were rated on the CBCL/1.5-5 and the C-TRF/1.5-5 by their mothers, kindergarten teachers and therapists. Maternal psychopathology was assessed by self-rating with the SCL-90-R and the BDI. The appropriateness of the depression-distortion hypothesis, as well as two alternatives, the accuracy and the combinatory model, were subsequently analysed by structural equation modelling (SEM), including the ratings of all three informants. Model fit and parameter estimation supported the distortion model, suggesting that ratings of child behaviour by mothers may be biased by maternal psychopathology. Findings are discussed with regard to the existing cross-informant literature, with particular consideration of the distortion hypothesis and third person ratings of child psychopathology in preschool age.

Studies of Al-Ti Alloys by SEM

NASA Astrophysics Data System (ADS)

Yildiz, K.; Atici, Y.; Keşlİ Oǧlu, K.; Yaşar, E.

2007-04-01

Al-Ti (1, 2 wt. %) alloys were investigated by Scanning Electron Microscopy (SEM). SEM observations and energy-dispersive x-ray analyses (EDX) showed that the phase structure of Al-Ti (1 %) alloy at 165 μm/s is composed of Al matrix and C, Ni, Fe and Si particles and the Al-Ti (1 %) alloys at 16 and 8 μm/s have only the Al matrix and C particles. It was also found that the Al-Ti (2 %) form the Al matrix and intermetallic TiAl.

Interlaboratory comparison of measurements of acid-volatile sulfide and simultaneously extracted nickel in spiked sediments

USGS Publications Warehouse

Brumbaugh, William G.; Hammerschmidt, Chad R.; Zanella, Luciana; Rogevich, Emily; Salata, Gregory; Bolek, Radoslaw

2011-01-01

An interlaboratory comparison of acid-volatile sulfide (AVS) and simultaneously extracted nickel (SEM_Ni) measurements of sediments was conducted among five independent laboratories. Relative standard deviations for the seven test samples ranged from 5.6 to 71% (mean = 25%) for AVS and from 5.5 to 15% (mean = 10%) for SEM_Ni. These results are in stark contrast to a recently published study that indicated AVS and SEM analyses were highly variable among laboratories.

Analysis of the factors influencing healthcare professionals' adoption of mobile electronic medical record (EMR) using the unified theory of acceptance and use of technology (UTAUT) in a tertiary hospital.

PubMed

Kim, Seok; Lee, Kee-Hyuck; Hwang, Hee; Yoo, Sooyoung

2016-01-30

Although the factors that affect the end-user's intention to use a new system and technology have been researched, the previous studies have been theoretical and do not verify the factors that affected the adoption of a new system. Thus, this study aimed to confirm the factors that influence users' intentions to utilize a mobile electronic health records (EMR) system using both a questionnaire survey and a log file analysis that represented the real use of the system. After observing the operation of a mobile EMR system in a tertiary university hospital for seven months, we performed an offline survey regarding the user acceptance of the system based on the Unified Theory of Acceptance and Use of Technology (UTAUT) and the Technology Acceptance Model (TAM). We surveyed 942 healthcare professionals over two weeks and performed a structural equation modeling (SEM) analysis to identify the intention to use the system among the participants. Next, we compared the results of the SEM analysis with the results of the analyses of the actual log files for two years to identify further insights into the factors that affected the intention of use. For these analyses, we used SAS 9.0 and AMOS 21. Of the 942 surveyed end-users, 48.3 % (23.2 % doctors and 68.3 % nurses) responded. After eliminating six subjects who completed the survey insincerely, we conducted the SEM analyses on the data from 449 subjects (65 doctors and 385 nurses). The newly suggested model satisfied the standards of model fitness, and the intention to use it was especially high due to the influences of Performance Expectancy on Attitude and Attitude. Based on the actual usage log analyses, both the doctors and nurses used the menus to view the inpatient lists, alerts, and patients' clinical data with high frequency. Specifically, the doctors frequently retrieved laboratory results, and the nurses frequently retrieved nursing notes and used the menu to assume the responsibilities of nursing work. In this study, the end-users' intentions to use the mobile EMR system were particularly influenced by Performance Expectancy and Attitude. In reality, the usage log revealed high-frequency use of the functions to improve the continuity of care and work efficiency. These results indicate the influence of the factor of performance expectancy on the intention to use the mobile EMR system. Consequently, we suggest that when determining the implementation of mobile EMR systems, the functions that are related to workflow with ability to increase performance should be considered first.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cooke, Gary A.; Pestovich, John A.; Huber, Heinz J.

This report presents the results for solid phase characterization (SPC) of solid samples removed from tank 241-C-108 (C-108) on August 12-13,2012, using the off-riser sampler. Samples were received at the 222-S Laboratory on August 13 and were described and photographed. The SPC analyses that were performed include scanning electron microscopy (SEM) using the ASPEX(R)l scanning electron microscope, X-ray diffraction (XRD) using the Rigaku(R) 2 MiniFlex X-ray diffractometer, and polarized light microscopy (PLM) using the Nikon(R) 3 Eclipse Pol optical microscope. The SEM is equipped with an energy dispersive X-ray spectrometer (EDS) to provide chemical information. Gary A. Cooke conducted themore » SEM analysis, John A. Pestovich performed the XRD analysis, and Dr. Heinz J. Huber performed the PLM examination. The results of these analyses are presented here.« less

Assessing the utility of FIB-SEM images for shale digital rock physics

NASA Astrophysics Data System (ADS)

Kelly, Shaina; El-Sobky, Hesham; Torres-Verdín, Carlos; Balhoff, Matthew T.

2016-09-01

Shales and other unconventional or low permeability (tight) reservoirs house vast quantities of hydrocarbons, often demonstrate considerable water uptake, and are potential repositories for fluid sequestration. The pore-scale topology and fluid transport mechanisms within these nanoporous sedimentary rocks remain to be fully understood. Image-informed pore-scale models are useful tools for studying porous media: a debated question in shale pore-scale petrophysics is whether there is a representative elementary volume (REV) for shale models? Furthermore, if an REV exists, how does it differ among petrophysical properties? We obtain three dimensional (3D) models of the topology of microscale shale volumes from image analysis of focused ion beam-scanning electron microscope (FIB-SEM) image stacks and investigate the utility of these models as a potential REV for shale. The scope of data used in this work includes multiple local groups of neighboring FIB-SEM images of different microscale sizes, corresponding core-scale (milli- and centimeters) laboratory data, and, for comparison, series of two-dimensional (2D) cross sections from broad ion beam SEM images (BIB-SEM), which capture a larger microscale field of view than the FIB-SEM images; this array of data is larger than the majority of investigations with FIB-SEM-derived microscale models of shale. Properties such as porosity, organic matter content, and pore connectivity are extracted from each model. Assessments of permeability with single phase, pressure-driven flow simulations are performed in the connected pore space of the models using the lattice-Boltzmann method. Calculated petrophysical properties are compared to those of neighboring FIB-SEM images and to core-scale measurements of the sample associated with the FIB-SEM sites. Results indicate that FIB-SEM images below ∼5000 μm3 volume (the largest volume analyzed) are not a suitable REV for shale permeability and pore-scale networks; i.e. field of view is compromised at the expense of detailed, but often unconnected, nanopore morphology. Further, we find that it is necessary to acquire several local FIB-SEM or BIB-SEM images and correlate their extracted geometric properties to improve the likelihood of achieving representative values of porosity and organic matter volume. Our work indicates that FIB-SEM images of microscale volumes of shale are a qualitative tool for petrophysical and transport analysis. Finally, we offer alternatives for quantitative pore-scale assessments of shale.

The assessment of the performance of covariance-based structural equation modeling and partial least square path modeling

NASA Astrophysics Data System (ADS)

Aimran, Ahmad Nazim; Ahmad, Sabri; Afthanorhan, Asyraf; Awang, Zainudin

2017-05-01

Structural equation modeling (SEM) is the second generation statistical analysis technique developed for analyzing the inter-relationships among multiple variables in a model. Previous studies have shown that there seemed to be at least an implicit agreement about the factors that should drive the choice between covariance-based structural equation modeling (CB-SEM) and partial least square path modeling (PLS-PM). PLS-PM appears to be the preferred method by previous scholars because of its less stringent assumption and the need to avoid the perceived difficulties in CB-SEM. Along with this issue has been the increasing debate among researchers on the use of CB-SEM and PLS-PM in studies. The present study intends to assess the performance of CB-SEM and PLS-PM as a confirmatory study in which the findings will contribute to the body of knowledge of SEM. Maximum likelihood (ML) was chosen as the estimator for CB-SEM and was expected to be more powerful than PLS-PM. Based on the balanced experimental design, the multivariate normal data with specified population parameter and sample sizes were generated using Pro-Active Monte Carlo simulation, and the data were analyzed using AMOS for CB-SEM and SmartPLS for PLS-PM. Comparative Bias Index (CBI), construct relationship, average variance extracted (AVE), composite reliability (CR), and Fornell-Larcker criterion were used to study the consequence of each estimator. The findings conclude that CB-SEM performed notably better than PLS-PM in estimation for large sample size (100 and above), particularly in terms of estimations accuracy and consistency.

The effects of sexually explicit material use on romantic relationship dynamics

PubMed Central

Minarcik, Jenny; Wetterneck, Chad T.; Short, MARY B.

2016-01-01

Background and aims Pornography use has become increasingly common. Studies have shown that individuals who use sexually explicit materials (SEMs) report negative effects (Schneider, 2000b). However, Bridges (2008b) found that couples who use SEM together have higher relationship satisfaction than those who use SEM independently. A further investigation into various types of SEM use in relationships may highlight how SEM is related to various areas of couple satisfaction. Thus, the purpose of the current study is to examine the impact of SEM use related to different relationship dynamics. Methods The current study included a college and Internet sample of 296 participants divided into groups based upon the SEM use in relationships (i.e., SEM alone, SEM use with partner, and no SEM use). Results There were significant differences between groups in relationship satisfaction [F(2, 252) = 3.69, p = .026], intimacy [F(2, 252) = 7.95, p = <.001], and commitment [F(2, 252) = 5.30, p = .006]. Post-hoc analyses revealed additional differences in relationship satisfaction [t(174) = 2.13, p = .035] and intimacy [t(174) = 2.76, p = .006] based on the frequency of SEM use. Discussion Further exploration of the SEM use function in couples will provide greater understanding of its role in romantic relationships. PMID:27784182

Scanning Electron Microscope-Cathodoluminescence Analysis of Rare-Earth Elements in Magnets.

PubMed

Imashuku, Susumu; Wagatsuma, Kazuaki; Kawai, Jun

2016-02-01

Scanning electron microscope-cathodoluminescence (SEM-CL) analysis was performed for neodymium-iron-boron (NdFeB) and samarium-cobalt (Sm-Co) magnets to analyze the rare-earth elements present in the magnets. We examined the advantages of SEM-CL analysis over conventional analytical methods such as SEM-energy-dispersive X-ray (EDX) spectroscopy and SEM-wavelength-dispersive X-ray (WDX) spectroscopy for elemental analysis of rare-earth elements in NdFeB magnets. Luminescence spectra of chloride compounds of elements in the magnets were measured by the SEM-CL method. Chloride compounds were obtained by the dropwise addition of hydrochloric acid on the magnets followed by drying in vacuum. Neodymium, praseodymium, terbium, and dysprosium were separately detected in the NdFeB magnets, and samarium was detected in the Sm-Co magnet by the SEM-CL method. In contrast, it was difficult to distinguish terbium and dysprosium in the NdFeB magnet with a dysprosium concentration of 1.05 wt% by conventional SEM-EDX analysis. Terbium with a concentration of 0.02 wt% in an NdFeB magnet was detected by SEM-CL analysis, but not by conventional SEM-WDX analysis. SEM-CL analysis is advantageous over conventional SEM-EDX and SEM-WDX analyses for detecting trace rare-earth elements in NdFeB magnets, particularly dysprosium and terbium.

On the Benefits of Latent Variable Modeling for Norming Scales: The Case of the "Supports Intensity Scale-Children's Version"

ERIC Educational Resources Information Center

Seo, Hyojeong; Little, Todd D.; Shogren, Karrie A.; Lang, Kyle M.

2016-01-01

Structural equation modeling (SEM) is a powerful and flexible analytic tool to model latent constructs and their relations with observed variables and other constructs. SEM applications offer advantages over classical models in dealing with statistical assumptions and in adjusting for measurement error. So far, however, SEM has not been fully used…

A comparison using Faraday cups with 1013 Ω amplifiers and a secondary electron multiplier to measure Os isotopes by negative thermal ionization mass spectrometry

NASA Astrophysics Data System (ADS)

Wang, G. Q.; Xu, J. F.

2017-12-01

According to the Johnson-Nyquist noise equation, the value of electron noise is proportional to the square root of the resistor value. This ralationship gives a theoretical improvement of in the signal/noise ratio by going from 1011 Ω to 1013 Ω amplifiers for Faraday detection in thermal ionization mass spectrometry (TIMS). We measured Os isotopes using static Faraday cups with 1013 Ω amplifiers in a negative thermal ionization mass spectrometry (NTIMS) and compared the results with those obtained with 1011 Ω amplifiers and by peak hopping on a single secondary electron multiplier (SEM). We analysed large loads of Os (1 μg) at a range of intensities of 187OsO3 (0.02 - 10 mV) in addition to small loads of Os (5 - 500 pg) to compare the results of the three methods. Using 1013 Ω amplifiers, the long time reproducibility determined from Merck Os was 187Os/188Os = 0.1211 ±0.0086 and 0.120229 ±0.000034 at 0.02 mV and 10 mV of 187OsO3 intensities. Meanwhile, the analysed JMC Os loading 5 and 500 pg showed 187Os/188Os = 0.10669 ±0.00036 and 0.106807 ± 0.000023. In comparison, the values measured by SEM were 187Os/188Os = 0.10704 ± 0.00056 and 0.10690 ± 0.00013. All errors are in 2 SD. Both the accuracy and precision analysed using the 1013 Ω amplifiers and SEM are identical when the Os amounts are within 10 - 50 pg. However, the former analysis time can be shortened by approximately 2/3. SEM measurement is still the most precise method for Os amounts 10 pg, but the analyses of 1013 Ω amplifiers suggest they are significantly better than SEM for Os amounts > 50 pg.

Bootstrap Estimation of Sample Statistic Bias in Structural Equation Modeling.

ERIC Educational Resources Information Center

Thompson, Bruce; Fan, Xitao

This study empirically investigated bootstrap bias estimation in the area of structural equation modeling (SEM). Three correctly specified SEM models were used under four different sample size conditions. Monte Carlo experiments were carried out to generate the criteria against which bootstrap bias estimation should be judged. For SEM fit indices,…

High-resolution 3D analyses of the shape and internal constituents of small volcanic ash particles: The contribution of SEM micro-computed tomography (SEM micro-CT)

NASA Astrophysics Data System (ADS)

Vonlanthen, Pierre; Rausch, Juanita; Ketcham, Richard A.; Putlitz, Benita; Baumgartner, Lukas P.; Grobéty, Bernard

2015-02-01

The morphology of small volcanic ash particles is fundamental to our understanding of magma fragmentation, and in transport modeling of volcanic plumes and clouds. Until recently, the analysis of 3D features in small objects (< 250 μm) was either restricted to extrapolations from 2D approaches, partial stereo-imaging, or CT methods having limited spatial resolution and/or accessibility. In this study, an X-ray computed-tomography technique known as SEM micro-CT, also called 3D X-ray ultramicroscopy (3D XuM), was used to investigate the 3D morphology of small volcanic ash particles (125-250 μm sieve fraction), as well as their vesicle and microcrystal distribution. The samples were selected from four stratigraphically well-established tephra layers of the Meerfelder Maar (West Eifel Volcanic Field, Germany). Resolution tests performed on a Beametr v1 pattern sample along with Monte Carlo simulations of X-ray emission volumes indicated that a spatial resolution of 0.65 μm was obtained for X-ray shadow projections using a standard thermionic SEM and a bulk brass target as X-ray source. Analysis of a smaller volcanic ash particle (64-125 μm sieve fraction) showed that features with volumes > 20 μm3 (~ 3.5 μm in diameter) can be successfully reconstructed and quantified. In addition, new functionalities of the Blob3D software were developed to allow the particle shape factors frequently used as input parameters in ash transport and dispersion models to be calculated. This study indicates that SEM micro-CT is very well suited to quantify the various aspects of shape in fine volcanic ash, and potentially also to investigate the 3D morphology and internal structure of any object < 0.1 mm3.

In severely suicidal young adults, hopelessness, depressive symptoms, and suicidal ideation constitute a single syndrome.

PubMed

Shahar, Golan; Bareket, Liad; Rudd, M David; Joiner, Thomas E

2006-07-01

Despite voluminous research on the role of hopelessness and depression in suicidality, a systematic examination of various causal models pertaining to these variables is conspicuous in its absence. The directions of relationships between the three variables were examined by means of a prospective-longitudinal, cross-lagged, three-wave design in a severely suicidal young adults. Structural Equation Modeling (SEM) analyses revealed synchronous, but not longitudinal, associations between hopelessness, depressive symptoms, and suicidal ideation. In severely suicidal young adults, the three clinical constructs appear to constitute a single depressive syndrome.

On the Benefits of Latent Variable Modeling for Norming Scales: The Case of the "Supports Intensity Scale--Children's Version"

ERIC Educational Resources Information Center

Seo, Hyojeong; Little, Todd D.; Shogren, Karrie A.; Lang, Kyle M.

2016-01-01

Structural equation modeling (SEM) is a powerful and flexible analytic tool to model latent constructs and their relations with observed variables and other constructs. SEM applications offer advantages over classical models in dealing with statistical assumptions and in adjusting for measurement error. So far, however, SEM has not been fully used…

Single-entry models (SEMs) for scheduled services: Towards a roadmap for the implementation of recommended practices.

PubMed

Lopatina, Elena; Damani, Zaheed; Bohm, Eric; Noseworthy, Tom W; Conner-Spady, Barbara; MacKean, Gail; Simpson, Chris S; Marshall, Deborah A

2017-09-01

Long waiting times for elective services continue to be a challenging issue. Single-entry models (SEMs) are used to increase access to and flow through the healthcare system. This paper provides a roadmap for healthcare decision-makers, managers, physicians, and researchers to guide implementation and management of successful and sustainable SEMs. The roadmap was informed by an inductive qualitative synthesis of the findings from a deliberative process (a symposium on SEMs, with clinicians, researchers, senior policy-makers, healthcare managers, and patient representatives) and focus groups with the symposium participants. SEMs are a promising strategy to improve the management of referrals and represent one approach to reduce waiting times. The SEMs roadmap outlines current knowledge about SEMs and critical success factors for SEMs' implementation and management. This SEM roadmap is intended to help clinicians, decision-makers, managers, and researchers interested in developing new or strengthening existing SEMs. We consider this roadmap to be a living document that will continue to evolve as we learn more about implementing and managing sustainable SEMs. Copyright © 2017 Elsevier B.V. All rights reserved.

Behavioral change theories can inform the prediction of young adults' adoption of a plant-based diet.

PubMed

Wyker, Brett A; Davison, Kirsten K

2010-01-01

Drawing on the Theory of Planned Behavior (TPB) and the Transtheoretical Model (TTM), this study (1) examines links between stages of change for following a plant-based diet (PBD) and consuming more fruits and vegetables (FV); (2) tests an integrated theoretical model predicting intention to follow a PBD; and (3) identifies associated salient beliefs. Cross-sectional. Large public university in the northeastern United States. 204 college students. TPB and TTM constructs were assessed using validated scales. Outcome, normative, and control beliefs were measured using open-ended questions. The overlap between stages of change for FV consumption and adopting a PBD was assessed using Spearman rank correlation analysis and cross-tab comparisons. The proposed model predicting adoption of a PBD was tested using structural equation modeling (SEM). Salient beliefs were coded using automatic response coding software. No association was found between stages of change for FV consumption and following a PBD. Results from SEM analyses provided support for the proposed model predicting intention to follow a PBD. Gender differences in salient beliefs for following a PBD were found. Results demonstrate the potential for effective theory-driven and stage-tailored public health interventions to promote PBDs. Copyright 2010 Society for Nutrition Education. Published by Elsevier Inc. All rights reserved.

A Two-Stage Approach to Synthesizing Covariance Matrices in Meta-Analytic Structural Equation Modeling

ERIC Educational Resources Information Center

Cheung, Mike W. L.; Chan, Wai

2009-01-01

Structural equation modeling (SEM) is widely used as a statistical framework to test complex models in behavioral and social sciences. When the number of publications increases, there is a need to systematically synthesize them. Methodology of synthesizing findings in the context of SEM is known as meta-analytic SEM (MASEM). Although correlation…

The role of advanced reactive surface area characterization in improving predictions of mineral reaction rates

NASA Astrophysics Data System (ADS)

Beckingham, L. E.; Zhang, S.; Mitnick, E.; Cole, D. R.; Yang, L.; Anovitz, L. M.; Sheets, J.; Swift, A.; Kneafsey, T. J.; Landrot, G.; Mito, S.; Xue, Z.; Steefel, C. I.; DePaolo, D. J.; Ajo Franklin, J. B.

2014-12-01

Geologic sequestration of CO2 in deep sedimentary formations is a promising means of mitigating carbon emissions from coal-fired power plants but the long-term fate of injected CO2 is challenging to predict. Reactive transport models are used to gain insight over long times but rely on laboratory determined mineral reaction rates that have been difficult to extrapolate to field systems. This, in part, is due to a lack of understanding of mineral reactive surface area. Many models use an arbitrary approximation of reactive surface area, applying orders of magnitude scaling factors to measured BET or geometric surface areas. Recently, a few more sophisticated approaches have used 2D and 3D image analyses to determine mineral-specific reactive surface areas that account for the accessibility of minerals. However, the ability of these advanced surface area estimates to improve predictions of mineral reaction rates has yet to be determined. In this study, we fuse X-ray microCT, SEM QEMSCAN, XRD, SANS, and SEM-FIB analysis to determine mineral-specific accessible reactive surface areas for a core sample from the Nagaoka pilot CO2 injection site (Japan). This sample is primarily quartz, plagioclase, smectite, K-feldspar, and pyroxene. SEM imaging shows abundant smectite cement and grain coatings that decrease the fluid accessibility of other minerals. However, analysis of FIB-SEM images reveals that smectite nano-pores are well connected such that access to underlying minerals is not occluded by smectite coatings. Mineral-specific accessible surfaces are determined, accounting for the connectivity of the pore space with and without connected smectite nano-pores. The large-scale impact of variations in accessibility and dissolution rates are then determined through continuum scale modeling using grid-cell specific information on accessible surface areas. This approach will be compared with a traditional continuum scale model using mineral abundances and common surface area estimates. Ultimately, the effectiveness of advanced surface area characterization to improve mineral dissolution rates will be evaluated by comparison of model results with dissolution rates measured from a flow-through column experiment.

Language-related cerebral oscillatory changes are influenced equally by genetic and environmental factors.

PubMed

Araki, Toshihiko; Hirata, Masayuki; Yanagisawa, Takufumi; Sugata, Hisato; Onishi, Mai; Watanabe, Yoshiyuki; Ogata, Soshiro; Honda, Chika; Hayakawa, Kazuo; Yorifuji, Shiro

2016-11-15

Twin studies have suggested that there are genetic influences on inter-individual variation in terms of verbal abilities, and candidate genes have been identified by genome-wide association studies. However, the brain activities under genetic influence during linguistic processing remain unclear. In this study, we investigated neuromagnetic activities during a language task in a group of 28 monozygotic (MZ) and 12 dizygotic (DZ) adult twin pairs. We examined the spatio-temporal distribution of the event-related desynchronizations (ERDs) in the low gamma band (25-50Hz) using beamformer analyses and time-frequency analyses. Heritability was evaluated by comparing the respective MZ and DZ correlations. The genetic and environmental contributions were then estimated by structural equation modeling (SEM). We found that the peaks of the low gamma ERDs were localized to the left frontal area. The power of low gamma ERDs in this area exhibited higher similarity between MZ twins than that between DZ twins. SEM estimated the genetic contribution as approximately 50%. In addition, these powers were negatively correlated with the behavioral verbal scores. These results improve our understanding of how genetic and environmental factors influence cerebral activities during linguistic processes. Copyright © 2016 Elsevier Inc. All rights reserved.

Viewing of Internet-Based Sexually Explicit Media as a Risk Factor for Condomless Anal Sex among Men Who Have Sex with Men in Four U.S. Cities

PubMed Central

Antebi-Gruszka, Nadav; Downing, Martin J.

2016-01-01

The last decade has seen a dramatic increase in the availability of sexually explicit media (SEM) on the Internet. Men who have sex with men (MSM) report near universal use of SEM. However, this widespread use of SEM among MSM may contribute to more condomless anal sex. To examine the association of viewing SEM on the Internet and the number of condomless anal sex encounters among MSM, in 2012, an online survey was conducted of 265 MSM from New York, Philadelphia, Baltimore, or Washington D.C. who reported viewing SEM online in the past 3 months. Analyses were performed using negative binomial regression. Nearly all men reported viewing SEM featuring anal sex with (91%) or without (92%) condoms in the past 3 months. Neither viewing more hours of SEM per week or compulsively viewing SEM were associated with more condomless anal sex encounters. Rather, viewing a greater proportion of SEM containing condomless anal sex was associated with engaging in more condomless anal encounters (IRR = 1.25), while viewing a greater proportion of SEM containing anal sex where condoms were used was associated with fewer condomless anal sex encounters (IRR = 0.62). MSM reported that viewing SEM caused changes in their sexual fantasies, desires, and behaviors. These findings provide important insights for health policy and the design of interventions addressing SEM and condomless sex among MSM. The findings suggest that condom use by SEM performers may benefit not only actor health, but also have health implications for SEM viewers. PMID:27119990

The Adolescent's Competency for Interacting with Alcohol as a Determinant of Intake: The Role of Self-Regulation.

PubMed

de la Fuente, Jesús; Cubero, Inmaculada; Sánchez-Amate, Mari Carmen; Peralta, Francisco J; Garzón, Angélica; Fiz Pérez, Javier

2017-01-01

The competency for interacting with alcohol is a highly useful Educational Psychology model for preventing and for understanding the different behavioral levels of this interaction. Knowledge of facts, concepts and principles about alcohol use, self-regulated behavior, and attitudes toward alcohol are predictive of adequate interaction with alcohol. The objective of this study was to empirically evaluate this postulated relationship. A total of 328 Spanish adolescents participated, between the ages of 12 and 17. All were enrolled in 1st-4th year of compulsory secondary education, in the context of the ALADO Program for prevention of alcohol intake in adolescents. An ex post facto design was used, with inferential analyses and SEM analyses. Results show an interdependence relationship, with significant structural prediction between the behavioral levels defined and the level of alcohol intake, with principles, self-regulating control and attitudes carrying more weight. Analyses are presented, as are implications for psychoeducational intervention using preventive programs based on this competency model.

The Adolescent's Competency for Interacting with Alcohol as a Determinant of Intake: The Role of Self-Regulation

PubMed Central

de la Fuente, Jesús; Cubero, Inmaculada; Sánchez-Amate, Mari Carmen; Peralta, Francisco J.; Garzón, Angélica; Fiz Pérez, Javier

2017-01-01

The competency for interacting with alcohol is a highly useful Educational Psychology model for preventing and for understanding the different behavioral levels of this interaction. Knowledge of facts, concepts and principles about alcohol use, self-regulated behavior, and attitudes toward alcohol are predictive of adequate interaction with alcohol. The objective of this study was to empirically evaluate this postulated relationship. A total of 328 Spanish adolescents participated, between the ages of 12 and 17. All were enrolled in 1st–4th year of compulsory secondary education, in the context of the ALADO Program for prevention of alcohol intake in adolescents. An ex post facto design was used, with inferential analyses and SEM analyses. Results show an interdependence relationship, with significant structural prediction between the behavioral levels defined and the level of alcohol intake, with principles, self-regulating control and attitudes carrying more weight. Analyses are presented, as are implications for psychoeducational intervention using preventive programs based on this competency model. PMID:29123492

Structural equation modeling in pediatric psychology: overview and review of applications.

PubMed

Nelson, Timothy D; Aylward, Brandon S; Steele, Ric G

2008-08-01

To describe the use of structural equation modeling (SEM) in the Journal of Pediatric Psychology (JPP) and to discuss the usefulness of SEM applications in pediatric psychology research. The use of SEM in JPP between 1997 and 2006 was examined and compared to leading journals in clinical psychology, clinical child psychology, and child development. SEM techniques were used in <4% of the empirical articles appearing in JPP between 1997 and 2006. SEM was used less frequently in JPP than in other clinically relevant journals over the past 10 years. However, results indicated a recent increase in JPP studies employing SEM techniques. SEM is an under-utilized class of techniques within pediatric psychology research, although investigations employing these methods are becoming more prevalent. Despite its infrequent use to date, SEM is a potentially useful tool for advancing pediatric psychology research with a number of advantages over traditional statistical methods.

Multitemporal Three Dimensional Imaging of Volcanic Products on the Macro- and Micro- Scale

NASA Astrophysics Data System (ADS)

Carter, A. J.; Ramsey, M. S.; Durant, A. J.; Skilling, I. P.

2006-12-01

Satellite data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) can be processed using a nadir- and backward-viewing band at the same wavelength to generate a Digital Elevation Model (DEM) at a maximum spatial resolution of 15 metres. Bezymianny Volcano (Kamchatka Peninsula, Russia) was chosen as a test target for multitemporal DEM generation. DEMs were used to generate a layer stack and calculate coarse topographic changes from 2000 to 2006, the most significant of which was a new crater that formed in spring 2005. The eruption that occurred on 11 January 2005 produced a pyroclastic deposit on the east flank, which was mapped and from which samples were collected in August 2005. A comparison was made between field-based observations of the deposit and micron-scale roughness (analogous to vesicularity) derived from ASTER thermal infrared data following the model described in Ramsey and Fink (1999) on lava domes. In order to investigate applying this technique to the pyroclastic deposits, 18 small samples from Bezymianny were selected for Scanning Electron Microscope (SEM) micron-scale analysis. The SEM image data were processed using software capable of calculating surface roughness and vesicle volume from stereo pairs: a statistical analysis of samples is presented using a high resolution grid of surface profiles. The results allow for a direct comparison to field, laboratory, and satellite-based estimates of micron-scale roughness. Prior to SEM processing, laboratory thermal emission spectra of the microsamples were collected and modelled to estimate vesicularity. Each data set was compared and assessed for coherence within the limitations of each technique. This study outlines the value of initially imaging at the macro-scale to assess major topographic changes over time at the volcano. This is followed by an example of the application of micro-scale SEM imaging and spectral deconvolution, highlighting the advantages of using multiple resolutions to analyse frequently overlapping products at Bezymianny.

Comparing the Effectiveness of Polymer Debriding Devices Using a Porcine Wound Biofilm Model.

PubMed

Wilkinson, Holly N; McBain, Andrew J; Stephenson, Christian; Hardman, Matthew J

2016-11-01

Objective: Debridement to remove necrotic and/or infected tissue and promote active healing remains a cornerstone of contemporary chronic wound management. While there has been a recent shift toward less invasive polymer-based debriding devices, their efficacy requires rigorous evaluation. Approach: This study was designed to directly compare monofilament debriding devices to traditional gauze using a wounded porcine skin biofilm model with standardized application parameters. Biofilm removal was determined using a surface viability assay, bacterial counts, histological assessment, and scanning electron microscopy (SEM). Results: Quantitative analysis revealed that monofilament debriding devices outperformed the standard gauze, resulting in up to 100-fold greater reduction in bacterial counts. Interestingly, histological and morphological analyses suggested that debridement not only removed bacteria, but also differentially disrupted the bacterially-derived extracellular polymeric substance. Finally, SEM of post-debridement monofilaments showed structural changes in attached bacteria, implying a negative impact on viability. Innovation: This is the first study to combine controlled and defined debridement application with a biologically relevant ex vivo biofilm model to directly compare monofilament debriding devices. Conclusion: These data support the use of monofilament debriding devices for the removal of established wound biofilms and suggest variable efficacy towards biofilms composed of different species of bacteria.

A Miniaturized Variable Pressure Scanning Electron Microscope (MVP-SEM) for the Surface of Mars: An Instrument for the Planetary Science Community

NASA Technical Reports Server (NTRS)

Edmunson, J.; Gaskin, J. A.; Danilatos, G.; Doloboff, I. J.; Effinger, M. R.; Harvey, R. P.; Jerman, G. A.; Klein-Schoder, R.; Mackie, W.; Magera, B.;

Quantitative assessments of arousal by analyzing microsaccade rates and pupil fluctuations prior to slow eye movements.

PubMed

Honda, Shogo; Kohama, Takeshi; Tanaka, Tatsuro; Yoshida, Hisashi

2014-01-01

It is well known that a decline of arousal level causes of poor performance of movements or judgments. Our previous study indicates that microsaccade (MS) rates and pupil fluctuations change before slow eye movements (SEMs) (Honda et al. 2013). However, SEM detection of this study was obscure and insufficient. In this study, we propose a new SEM detection method and analyze MS rates and pupil fluctuations while subjects maintain their gaze on a target. We modified Shin et al.'s method, which is optimized for EOG (electrooculography) signals, to extract the period of sustaining SEMs using a general eye tracker. After SEM detection, we analyzed MS rates and pupil fluctuations prior to the initiation of SEMs. As a result, we were able to detect SEMs more precisely than in our previous study. Moreover, the results of eye movements and pupil fluctuations analyses show that gradual rise of MS rate and longitudinal miosis are observed prior to the initiation of SEMs, which is consistent with our previous study. These findings suggest that monitoring eye movements and pupil fluctuations may evaluate the arousal level more precisely. Further, we found that these tendencies become more significant when they are restricted to the initial SEMs.

Structural Equation Modeling for the Associations between the Home Environment and Obesity-related Cardiovascular Fitness and Insulin Resistance among Hispanic Children

PubMed Central

Santiago-Torres, Margarita; Cui, Yuchen; Adams, Alexandra K.; Allen, David B.; Carrel, Aaron L.; Guo, Jessica Y.; LaRowe, Tara L.; Schoeller, Dale A.

2017-01-01

Objective To use the Structural Equation Modeling (SEM) to examined the associations between the home environment (HE), diet and physical activity (PA) factors with Hispanic children’s obesity, cardiovascular fitness (CVF), and insulin resistance (IR) measures. Design Cross-sectional analyses of the HE, diet and PA factors with children’s metabolic health. Setting Urban Community School, Wisconsin, USA. Subjects A total of 187 Hispanic children and their parents participated. Methods Children’s reported their diet and PA, and parents reported on the HE through self-administered questionnaires. Outcome variables were measured anthropometrics, CVF assessed using the Progressive Aerobic Cardiovascular Endurance Run (PACER). IR was determined with the homeostasis model assessment of insulin resistance (HOMAIR) in a subgroup of children (n=99) who participated in a one-time blood draw for fasting glucose and insulin concentrations. Results Parents exercise (β=0.33), home availability of PA equipment (β=0.20) and sugar-sweetened beverages (SSB) (β=0.19) were all associated with children’s PA and SSB consumption, respectively. Children’s SSB consumption (β=0.15) was associated with BMI z-score, which in turn, was associated with HOMAIR (β=0.61). In contrast, children’s PA (β=0.17) was associated with PACER z-score, which in turn was inversely associated with HOMAIR (β=−0.18). The SEM indices suggested a satisfactory model fit (Chi-square, Χ2 =53.1, comparative fix index=0.92, root-mean-squared error associated=0.04). Conclusions The SEM findings confirm the need to focus intervention efforts at the family level where parents are educated on making a healthier HE targeting poor diet and low levels of PA among Hispanic children who are disproportionally affected by obesity-related IR. PMID:26850309

On the Nature of SEM Estimates of ARMA Parameters.

ERIC Educational Resources Information Center

Hamaker, Ellen L.; Dolan, Conor V.; Molenaar, Peter C. M.

2002-01-01

Reexamined the nature of structural equation modeling (SEM) estimates of autoregressive moving average (ARMA) models, replicated the simulation experiments of P. Molenaar, and examined the behavior of the log-likelihood ratio test. Simulation studies indicate that estimates of ARMA parameters observed with SEM software are identical to those…

The reliability, precision and clinically meaningful change of walking assessments in multiple sclerosis.

PubMed

Learmonth, Yvonne C; Dlugonski, Deirdre D; Pilutti, Lara A; Sandroff, Brian M; Motl, Robert W

2013-11-01

Assessing walking impairment in those with multiple sclerosis (MS) is common, however little is known about the reliability, precision and clinically important change of walking outcomes. The purpose of this study was to determine the reliability, precision and clinically important change of the Timed 25-Foot Walk (T25FW), Six-Minute Walk (6MW), Multiple Sclerosis Walking Scale-12 (MSWS-12) and accelerometry. Data were collected from 82 persons with MS at two time points, six months apart. Analyses were undertaken for the whole sample and stratified based on disability level and usage of walking aids. Intraclass correlation coefficient (ICC) analyses established reliability: standard error of measurement (SEM) and coefficient of variation (CV) determined precision; and minimal detectable change (MDC) defined clinically important change. All outcome measures were reliable with precision and MDC varying between measures in the whole sample: T25FW: ICC=0.991; SEM=1 s; CV=6.2%; MDC=2.7 s (36%), 6MW: ICC=0.959; SEM=32 m; CV=6.2%; MDC=88 m (20%), MSWS-12: ICC=0.927; SEM=8; CV=27%; MDC=22 (53%), accelerometry counts/day: ICC=0.883; SEM=28450; CV=17%; MDC=78860 (52%), accelerometry steps/day: ICC=0.907; SEM=726; CV=16%; MDC=2011 (45%). Variation in these estimates was seen based on disability level and walking aid. The reliability of these outcomes is good and falls within acceptable ranges. Precision and clinically important change estimates provide guidelines for interpreting these outcomes in clinical and research settings.

Partially covered self-expandable metal stents versus polyethylene stents for malignant biliary obstruction: A cost-effectiveness analysis

PubMed Central

Barkun, Alan N; Adam, Viviane; Martel, Myriam; AlNaamani, Khalid; Moses, Peter L

2015-01-01

BACKGROUND/OBJECTIVE: Partially covered self-expandable metal stents (SEMS) and polyethylene stents (PES) are both commonly used in the palliation of malignant biliary obstruction. Although SEMS are significantly more expensive, they are more efficacious than PES. Accordingly, a cost-effectiveness analysis was performed. METHODS: A cost-effectiveness analysis compared the approach of initial placement of PES versus SEMS for the study population. Patients with malignant biliary obstruction underwent an endoscopic retrograde cholangiopancreatography to insert the initial stent. If the insertion failed, a percutaneous transhepatic cholangiogram was performed. If stent occlusion occurred, a PES was inserted at repeat endoscopic retrograde cholangiopancreatography, either in an outpatient setting or after admission to hospital if cholangitis was present. A third-party payer perspective was adopted. Effectiveness was expressed as the likelihood of no occlusion over the one-year adopted time horizon. Probabilities were based on a contemporary randomized clinical trial, and costs were issued from national references. Deterministic and probabilistic sensitivity analyses were performed. RESULTS: A PES-first strategy was both more expensive and less efficacious than an SEMS-first approach. The mean per-patient costs were US$6,701 for initial SEMS and US$20,671 for initial PES, which were associated with effectiveness probabilities of 65.6% and 13.9%, respectively. Sensitivity analyses confirmed the robustness of these results. CONCLUSION: At the time of initial endoscopic drainage for patients with malignant biliary obstruction undergoing palliative stenting, an initial SEMS insertion approach was both more effective and less costly than a PES-first strategy. PMID:26125107

Team performance in the Italian NHS: the role of reflexivity.

PubMed

Urbini, Flavio; Callea, Antonino; Chirumbolo, Antonio; Talamo, Alessandra; Ingusci, Emanuela; Ciavolino, Enrico

2018-04-09

Purpose The purpose of this paper is twofold: first, to investigate the goodness of the input-process-output (IPO) model in order to evaluate work team performance within the Italian National Health Care System (NHS); and second, to test the mediating role of reflexivity as an overarching process factor between input and output. Design/methodology/approach The Italian version of the Aston Team Performance Inventory was administered to 351 employees working in teams in the Italian NHS. Mediation analyses with latent variables were performed via structural equation modeling (SEM); the significance of total, direct, and indirect effect was tested via bootstrapping. Findings Underpinned by the IPO framework, the results of SEM supported mediational hypotheses. First, the application of the IPO model in the Italian NHS showed adequate fit indices, showing that the process mediates the relationship between input and output factors. Second, reflexivity mediated the relationship between input and output, influencing some aspects of team performance. Practical implications The results provide useful information for HRM policies improving process dimensions of the IPO model via the mediating role of reflexivity as a key role in team performance. Originality/value This study is one of a limited number of studies that applied the IPO model in the Italian NHS. Moreover, no study has yet examined the role of reflexivity as a mediator between input and output factors in the IPO model.

Some Esoteric Aspects of SEM that Its Practitioners Should Want to Know

ERIC Educational Resources Information Center

Rozeboom, William W.

2009-01-01

The topic of this article is the interpretation of structural equation modeling (SEM) solutions. Its purpose is to augment structural modeling's metatheoretic resources while enhancing awareness of how problematic is the causal significance of SEM-parameter solutions. Part I focuses on the nonuniqueness and consequent dubious interpretability of…

Graphical Tools for Linear Structural Equation Modeling

DTIC Science & Technology

2014-06-01

others. 4Kenny and Milan (2011) write, “Identification is perhaps the most difficult concept for SEM researchers to understand. We have seen SEM...model to using typical SEM software to determine model identifia- bility. Kenny and Milan (2011) list the following drawbacks: (i) If poor starting...the well known recursive and null rules (Bollen, 1989) and the regression rule (Kenny and Milan , 2011). A Simple Criterion for Identifying Individual

Bayesian Data-Model Fit Assessment for Structural Equation Modeling

ERIC Educational Resources Information Center

Levy, Roy

2011-01-01

Bayesian approaches to modeling are receiving an increasing amount of attention in the areas of model construction and estimation in factor analysis, structural equation modeling (SEM), and related latent variable models. However, model diagnostics and model criticism remain relatively understudied aspects of Bayesian SEM. This article describes…

Nuclear Electromagnetic Pulse Review

NASA Astrophysics Data System (ADS)

Dinallo, Michael

2011-04-01

Electromagnetic Pulse (EMP) from nuclear detonations have been observed for well over half a century. Beginning in the mid-to-late 1950s, the physics and modeling of EMP has been researched and will continue into the foreseeable future. The EMP environment propagates hundreds of miles from its origins and causes interference for all types of electronic instrumentation. This includes military, municipal and industry based electronic infrastructures such as power generation and distribution, command and control systems, systems used in financial and emergency services, electronic monitoring and communications networks, to mention some key infrastructure elements. Research into EMP has included originating physics, propagation and electromagnetic field coupling analyses and measurement-sensor development. Several methods for calculating EMP induced transient interference (voltage and current induction) will be briefly discussed and protection techniques reviewed. These methods can be mathematically simple or involve challenging boundary value solution techniques. A few illustrative calculations will demonstrate the concern for electronic system operability. Analyses such as the Wunsch-Bell model for electronic upset or damage, and the Singularity Expansion Method (SEM) put forth by Dr. Carl Baum, will facilitate the concern for EMP effects. The SEM determines the voltages and currents induced from transient electromagnetic fields in terms of natural modes of various types of electronic platforms (aerospace vehicles or land-based assets - fixed or mobile). Full-scale facility and laboratory simulation and response measurement approaches will be discussed. The talk will conclude with a discussion of some present research activities.

USING STRUCTURAL EQUATION MODELING TO INVESTIGATE RELATIONSHIPS AMONG ECOLOGICAL VARIABLES

EPA Science Inventory

This paper gives an introductory account of Structural Equation Modeling (SEM) and demonstrates its application using LISREL< with a model utilizing environmental data. Using nine EMAP data variables, we analyzed their correlation matrix with an SEM model. The model characterized...

Investigating the role of personal and context-related factors in convenience foods consumption.

PubMed

Contini, Caterina; Boncinelli, Fabio; Gerini, Francesca; Scozzafava, Gabriele; Casini, Leonardo

2018-07-01

In the scenario of food consumptions, we witness the consumer's growing consideration for the "convenience" attribute. Our study intends to understand the consumer behaviour towards convenience-processed foods by analysing in a single model the role of beliefs, personal traits, social influence and market availability. We applied a Structural Equation Model (SEM) to a representative sample of 426 Italian consumers. The results show a correlation between intention to consume convenience-processed foods and social influence, market availability and several personal traits, suggesting strategies for the development of the convenience food market. Copyright © 2018 Elsevier Ltd. All rights reserved.

Sensitivity analysis for linear structural equation models, longitudinal mediation with latent growth models and blended learning in biostatistics education

NASA Astrophysics Data System (ADS)

Sullivan, Adam John

In chapter 1, we consider the biases that may arise when an unmeasured confounder is omitted from a structural equation model (SEM) and sensitivity analysis techniques to correct for such biases. We give an analysis of which effects in an SEM are and are not biased by an unmeasured confounder. It is shown that a single unmeasured confounder will bias not just one but numerous effects in an SEM. We present sensitivity analysis techniques to correct for biases in total, direct, and indirect effects when using SEM analyses, and illustrate these techniques with a study of aging and cognitive function. In chapter 2, we consider longitudinal mediation with latent growth curves. We define the direct and indirect effects using counterfactuals and consider the assumptions needed for identifiability of those effects. We develop models with a binary treatment/exposure followed by a model where treatment/exposure changes with time allowing for treatment/exposure-mediator interaction. We thus formalize mediation analysis with latent growth curve models using counterfactuals, makes clear the assumptions and extends these methods to allow for exposure mediator interactions. We present and illustrate the techniques with a study on Multiple Sclerosis(MS) and depression. In chapter 3, we report on a pilot study in blended learning that took place during the Fall 2013 and Summer 2014 semesters here at Harvard. We blended the traditional BIO 200: Principles of Biostatistics and created ID 200: Principles of Biostatistics and epidemiology. We used materials from the edX course PH207x: Health in Numbers: Quantitative Methods in Clinical & Public Health Research and used. These materials were used as a video textbook in which students would watch a given number of these videos prior to class. Using surveys as well as exam data we informally assess these blended classes from the student's perspective as well as a comparison of these students with students in another course, BIO 201: Introduction to Statistical Methods in Fall 2013 as well as students from BIO 200 in Fall semesters of 1992 and 1993. We then suggest improvements upon our original course designs and follow up with an informal look at how these implemented changes affected the second offering of the newly blended ID 200 in Summer 2014.

From patterns to causal understanding: Structural equation modeling (SEM) in soil ecology

USGS Publications Warehouse

Eisenhauer, Nico; Powell, Jeff R; Grace, James B.; Bowker, Matthew A.

2015-01-01

In this perspectives paper we highlight a heretofore underused statistical method in soil ecological research, structural equation modeling (SEM). SEM is commonly used in the general ecological literature to develop causal understanding from observational data, but has been more slowly adopted by soil ecologists. We provide some basic information on the many advantages and possibilities associated with using SEM and provide some examples of how SEM can be used by soil ecologists to shift focus from describing patterns to developing causal understanding and inspiring new types of experimental tests. SEM is a promising tool to aid the growth of soil ecology as a discipline, particularly by supporting research that is increasingly hypothesis-driven and interdisciplinary, thus shining light into the black box of interactions belowground.

Sample Size Requirements for Structural Equation Models: An Evaluation of Power, Bias, and Solution Propriety

ERIC Educational Resources Information Center

Wolf, Erika J.; Harrington, Kelly M.; Clark, Shaunna L.; Miller, Mark W.

2013-01-01

Determining sample size requirements for structural equation modeling (SEM) is a challenge often faced by investigators, peer reviewers, and grant writers. Recent years have seen a large increase in SEMs in the behavioral science literature, but consideration of sample size requirements for applied SEMs often relies on outdated rules-of-thumb.…

Analyses of scattering characteristics of chosen anthropogenic aerosols

NASA Astrophysics Data System (ADS)

Kaszczuk, Miroslawa; Mierczyk, Zygmunt; Muzal, Michal

2008-10-01

In the work, analyses of scattering profile of chosen anthropogenic aerosols for two wavelengths (λ1 = 1064 nm and λ2 = 532 nm) were made. As an example of anthropogenic aerosol three different pyrotechnic mixtures (DM11, M2, M16) were taken. Main parameters of smoke particles were firstly analyzed and well described, taking particle shape and size into special consideration. Shape of particles was analyzed on the basis of SEM pictures, and particle size was measured. Participation of particles in each fixed fraction characterized by range of sizes was analyzed and parameters of smoke particles of characteristic sizes and function describing aerosol size distribution (ASD) were determinated. Analyses of scattering profiles were carried out on the basis of both model of scattering on spherical and nonspherical particles. In the case of spherical particles Rayleigh-Mie model was used and for nonspherical particles analyses firstly model of spheroids was used, and then Rayleigh-Mie one. For each characteristic particle one calculated value of four parameters (effective scattering cross section σSCA, effective backscattering cross section σBSCA, scattering efficiency QSCA, backscattering efficiency QBSCA) and value of backscattering coefficient β for whole particles population. Obtained results were compared with the same parameters calculated for natural aerosol (cirrus cloud).

Conductive resins improve charging and resolution of acquired images in electron microscopic volume imaging

PubMed Central

Nguyen, Huy Bang; Thai, Truc Quynh; Saitoh, Sei; Wu, Bao; Saitoh, Yurika; Shimo, Satoshi; Fujitani, Hiroshi; Otobe, Hirohide; Ohno, Nobuhiko

2016-01-01

Recent advances in serial block-face imaging using scanning electron microscopy (SEM) have enabled the rapid and efficient acquisition of 3-dimensional (3D) ultrastructural information from a large volume of biological specimens including brain tissues. However, volume imaging under SEM is often hampered by sample charging, and typically requires specific sample preparation to reduce charging and increase image contrast. In the present study, we introduced carbon-based conductive resins for 3D analyses of subcellular ultrastructures, using serial block-face SEM (SBF-SEM) to image samples. Conductive resins were produced by adding the carbon black filler, Ketjen black, to resins commonly used for electron microscopic observations of biological specimens. Carbon black mostly localized around tissues and did not penetrate cells, whereas the conductive resins significantly reduced the charging of samples during SBF-SEM imaging. When serial images were acquired, embedding into the conductive resins improved the resolution of images by facilitating the successful cutting of samples in SBF-SEM. These results suggest that improving the conductivities of resins with a carbon black filler is a simple and useful option for reducing charging and enhancing the resolution of images obtained for volume imaging with SEM. PMID:27020327

Typologies of sexually explicit media use among MSM: An application of latent class analysis

PubMed Central

Erickson, Darin J.; Galos, Dylan L; Smolenski, Derek, J.; Iantaffi, Alex; Rosser, B.R. Simon

2014-01-01

The viewing of sexually explicit media (SEM) is widespread, especially among men, and research linking SEM viewing and sexual behavior has shown a variety of results, some positive (e.g., sexuality education) and some negative (e.g., poorer body image). These results might be due to limitations in measuring SEM consumption, particularly around typology. The goal of the current study was to examine potential patterns of SEM viewing activities. Using data from an online survey of men who have sex with men (MSM), we conducted latent class analyses of 15 SEM activities. Results suggested a three-class solution. The most prevalent class included over 60% of men and was characterized by viewing primarily safer-sex or conventional behaviors. The second class included 32% of men and had a similar albeit amplified pattern of viewing. The final class included just 7% of men and was marked by high levels of viewing of all activities, including fetish and kink. Compared to the conventional or safer-sex class, the other classes had lower internalized homonegativity, lower condom use self-efficacy, and higher SEM consumption or dose. Implications for HIV prevention, sexuality research and the SEM industry are discussed. PMID:25642301

Analyzing latent state-trait and multiple-indicator latent growth curve models as multilevel structural equation models

PubMed Central

Geiser, Christian; Bishop, Jacob; Lockhart, Ginger; Shiffman, Saul; Grenard, Jerry L.

2013-01-01

Latent state-trait (LST) and latent growth curve (LGC) models are frequently used in the analysis of longitudinal data. Although it is well-known that standard single-indicator LGC models can be analyzed within either the structural equation modeling (SEM) or multilevel (ML; hierarchical linear modeling) frameworks, few researchers realize that LST and multivariate LGC models, which use multiple indicators at each time point, can also be specified as ML models. In the present paper, we demonstrate that using the ML-SEM rather than the SL-SEM framework to estimate the parameters of these models can be practical when the study involves (1) a large number of time points, (2) individually-varying times of observation, (3) unequally spaced time intervals, and/or (4) incomplete data. Despite the practical advantages of the ML-SEM approach under these circumstances, there are also some limitations that researchers should consider. We present an application to an ecological momentary assessment study (N = 158 youths with an average of 23.49 observations of positive mood per person) using the software Mplus (Muthén and Muthén, 1998–2012) and discuss advantages and disadvantages of using the ML-SEM approach to estimate the parameters of LST and multiple-indicator LGC models. PMID:24416023

Microstructural characterization and simulation of damage for geared sheet components

NASA Astrophysics Data System (ADS)

Gerstein, G.; Isik, K.; Gutknecht, F.; Sieczkarek, P.; Ewert, J.; Tekkaya, A. E.; Clausmeyer, T.; Nürnberger, F.

2017-09-01

The evolution of damage in geared components manufactured from steel sheets was investigated, to analyse the influence of damage caused by the sheet-bulk-metal forming. Due to the inhomogeneous and multi-axial deformation in the investigated parts, different aspects such as the location-dependent shape and size of voids are analysed by means of various microscopic methods. In particular, a method to characterize the state of damage evolution, i. e. void nucleation, growth and coalescence using scanning electron microscopy (SEM) is applied. The investigations reveal a strong dependence of the void area fraction, shape of voids and thus damage evolution on the loading mode. The microstructural analysis is complemented with FEM simulations using material models which consider the characteristics of the void evolution.

Screening and vaccination as determined by the Social Ecological Model and the Theory of Triadic Influence: a systematic review.

PubMed

Nyambe, Anayawa; Van Hal, Guido; Kampen, Jarl K

2016-11-17

Vaccination and screening are forms of primary and secondary prevention methods. These methods are recommended for controlling the spread of a vast number of diseases and conditions. To determine the most effective preventive methods to be used by a society, multi-level models have shown to be more effective than models that focus solely on individual level characteristics. The Social Ecological Model (SEM) and the Theory of Triadic Influence (TTI) are such models. The purpose of this systematic review was to identify main differences and similarities of SEM and TTI regarding screening and vaccination in order to prepare potentially successful prevention programs for practice. A systematic review was conducted. Separate literature searches were performed during January and February 2015 using Medline, Ovid, Proquest, PubMed, University of Antwerp Discovery Service and Web of Science, for articles that apply the SEM and TTI. A Data Extraction Form with mostly closed-end questions was developed to assist with data extraction. Aggregate descriptive statistics were utilized to summarize the general characteristics of the SEM and TTI as documented in the scientific literature. A total of 290 potentially relevant articles referencing the SEM were found. As for the TTI, a total of 131 potentially relevant articles were found. After strict evaluation for inclusion and exclusion criteria, 40 SEM studies and 46 TTI studies were included in the systematic review. The SEM and TTI are theoretical frameworks that share many theoretical concepts and are relevant for several types of health behaviors. However, they differ in the structure of the model, and in how the variables are thought to interact with each other, the TTI being a matrix while the SEM has a ring structure. The main difference consists of the division of the TTI into levels of causation (ultimate, distal and proximal) which are not considered within the levels of the SEM. It was further found that in the articles studied in this systematic review, both models are often considered effective, while the empirical basis of these (and other) conclusions reached by their authors is in many cases unclear or incompletely specified.

Quantifying Golgi structure using EM: combining volume-SEM and stereology for higher throughput.

PubMed

Ferguson, Sophie; Steyer, Anna M; Mayhew, Terry M; Schwab, Yannick; Lucocq, John Milton

2017-06-01

Investigating organelles such as the Golgi complex depends increasingly on high-throughput quantitative morphological analyses from multiple experimental or genetic conditions. Light microscopy (LM) has been an effective tool for screening but fails to reveal fine details of Golgi structures such as vesicles, tubules and cisternae. Electron microscopy (EM) has sufficient resolution but traditional transmission EM (TEM) methods are slow and inefficient. Newer volume scanning EM (volume-SEM) methods now have the potential to speed up 3D analysis by automated sectioning and imaging. However, they produce large arrays of sections and/or images, which require labour-intensive 3D reconstruction for quantitation on limited cell numbers. Here, we show that the information storage, digital waste and workload involved in using volume-SEM can be reduced substantially using sampling-based stereology. Using the Golgi as an example, we describe how Golgi populations can be sensed quantitatively using single random slices and how accurate quantitative structural data on Golgi organelles of individual cells can be obtained using only 5-10 sections/images taken from a volume-SEM series (thereby sensing population parameters and cell-cell variability). The approach will be useful in techniques such as correlative LM and EM (CLEM) where small samples of cells are treated and where there may be variable responses. For Golgi study, we outline a series of stereological estimators that are suited to these analyses and suggest workflows, which have the potential to enhance the speed and relevance of data acquisition in volume-SEM.

Structural Equation Modeling in Language Testing and Learning Research: A Review

ERIC Educational Resources Information Center

In'nami, Yo; Koizumi, Rie

2011-01-01

Despite the recent increase of structural equation modeling (SEM) in language testing and learning research and Kunnan's (1998) call for the proper use of SEM to produce useful findings, there seem to be no reviews about how SEM is applied in these areas or about the extent to which the current application accords with appropriate practices. To…

Correlated Raman micro-spectroscopy and scanning electron microscopy analyses of flame retardants in environmental samples: a micro-analytical tool for probing chemical composition, origin and spatial distribution.

PubMed

Ghosal, Sutapa; Wagner, Jeff

2013-07-07

We present correlated application of two micro-analytical techniques: scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) and Raman micro-spectroscopy (RMS) for the non-invasive characterization and molecular identification of flame retardants (FRs) in environmental dusts and consumer products. The SEM/EDS-RMS technique offers correlated, morphological, molecular, spatial distribution and semi-quantitative elemental concentration information at the individual particle level with micrometer spatial resolution and minimal sample preparation. The presented methodology uses SEM/EDS analyses for rapid detection of particles containing FR specific elements as potential indicators of FR presence in a sample followed by correlated RMS analyses of the same particles for characterization of the FR sub-regions and surrounding matrices. The spatially resolved characterization enabled by this approach provides insights into the distributional heterogeneity as well as potential transfer and exposure mechanisms for FRs in the environment that is typically not available through traditional FR analysis. We have used this methodology to reveal a heterogeneous distribution of highly concentrated deca-BDE particles in environmental dust, sometimes in association with identifiable consumer materials. The observed coexistence of deca-BDE with consumer material in dust is strongly indicative of its release into the environment via weathering/abrasion of consumer products. Ingestion of such enriched FR particles in dust represents a potential for instantaneous exposure to high FR concentrations. Therefore, correlated SEM/RMS analysis offers a novel investigative tool for addressing an area of important environmental concern.

Shockless spalling damage of alumina ceramic

NASA Astrophysics Data System (ADS)

Erzar, B.; Buzaud, E.

2012-05-01

Ceramic materials are commonly used to build multi-layer armour. However reliable test data is needed to identify correctly models and to be able to perform accurate numerical simulation of the dynamic response of armour systems. In this work, isentropic loading waves have been applied to alumina samples to induce spalling damage. The technique employed allows assessing carefully the strain-rate at failure and the dynamic strength. Moreover, specimens have been recovered and analysed using SEM. In a damaged but unbroken specimen, interactions between cracks has been highlighted illustrating the fragmentation process.

Structural equation modeling for observational studies

USGS Publications Warehouse

Grace, J.B.

2008-01-01

Structural equation modeling (SEM) represents a framework for developing and evaluating complex hypotheses about systems. This method of data analysis differs from conventional univariate and multivariate approaches familiar to most biologists in several ways. First, SEMs are multiequational and capable of representing a wide array of complex hypotheses about how system components interrelate. Second, models are typically developed based on theoretical knowledge and designed to represent competing hypotheses about the processes responsible for data structure. Third, SEM is conceptually based on the analysis of covariance relations. Most commonly, solutions are obtained using maximum-likelihood solution procedures, although a variety of solution procedures are used, including Bayesian estimation. Numerous extensions give SEM a very high degree of flexibility in dealing with nonnormal data, categorical responses, latent variables, hierarchical structure, multigroup comparisons, nonlinearities, and other complicating factors. Structural equation modeling allows researchers to address a variety of questions about systems, such as how different processes work in concert, how the influences of perturbations cascade through systems, and about the relative importance of different influences. I present 2 example applications of SEM, one involving interactions among lynx (Lynx pardinus), mongooses (Herpestes ichneumon), and rabbits (Oryctolagus cuniculus), and the second involving anuran species richness. Many wildlife ecologists may find SEM useful for understanding how populations function within their environments. Along with the capability of the methodology comes a need for care in the proper application of SEM.

Three-Dimensional (3D) Nanometrology Based on Scanning Electron Microscope (SEM) Stereophotogrammetry.

PubMed

Tondare, Vipin N; Villarrubia, John S; Vlada R, András E

2017-10-01

Three-dimensional (3D) reconstruction of a sample surface from scanning electron microscope (SEM) images taken at two perspectives has been known for decades. Nowadays, there exist several commercially available stereophotogrammetry software packages. For testing these software packages, in this study we used Monte Carlo simulated SEM images of virtual samples. A virtual sample is a model in a computer, and its true dimensions are known exactly, which is impossible for real SEM samples due to measurement uncertainty. The simulated SEM images can be used for algorithm testing, development, and validation. We tested two stereophotogrammetry software packages and compared their reconstructed 3D models with the known geometry of the virtual samples used to create the simulated SEM images. Both packages performed relatively well with simulated SEM images of a sample with a rough surface. However, in a sample containing nearly uniform and therefore low-contrast zones, the height reconstruction error was ≈46%. The present stereophotogrammetry software packages need further improvement before they can be used reliably with SEM images with uniform zones.

Synthesis and statistical modelling of dry sliding wear of Al 8011/6 vol.% AlB2 in situ composite

NASA Astrophysics Data System (ADS)

Kumar, Narendra; Singh, Sandeep Kumar; Gautam, Gaurav; Padap, Aditya Kumar; Mohan, Anita; Mohan, Sunil

2017-10-01

The present study has used response surface methodology (RSM) and central composite design (CCD) for modelling, using wear parameters to predict the wear performance of an Al 8011/6.0 vol.% AlB2 composite. The effect of applied load and sliding velocity was studied at five levels for a fixed sliding distance. To understand wear behaviour, sliding wear tests were planned according to CCD and performed on a pin-on-disc apparatus at ambient temperature. An analysis of variance (ANOVA) was conducted to show the relative significance of the parameters. A second-order regression model was developed to predict the wear loss and to establish the relationships between wear parameters. Response surface and contour plots were drawn to analyse the wear results. Worn surfaces were examined under scanning electron microscope (SEM), and energy dispersive spectroscopy (EDS) was used to interpret the operative wear mechanisms. Validation tests results show good agreement between experimental and predicted data. As an initial step of this study, AlB2 particles were reinforced in Al 8011 alloy by an in situ technique to synthesise an Al 8011/6.0 vol.% AlB2 composite. During synthesis an in situ reaction takes place between molten alloy and inorganic salt KBF4 at 850 °C, which leads to the formation of AlB2 particles. The composite was analysed by x-ray diffractometer (XRD) to detect the phases present, while optical and scanning electron microscopy (OM & SEM) were carried out to ascertain morphology and particle distribution. Hardness was evaluated by a Vickers hardness testing machine.

Effective model development of internal auditors in the village financial institution

NASA Astrophysics Data System (ADS)

Arsana, I. M. M.; Sugiarta, I. N.

2018-01-01

Designing an effective audit system is complex and challenging, and a focus on examining how internal audit drive improvement in three core performance dimensions ethicality, efficiency, and effectiveness in organization is needed. The problem of research is how the desain model and peripheral of supporter of effective supervation Village Credit Institution? Research of objectives is yielding the desain model and peripheral of supporter of effective supervation Village Credit Institution. Method Research use data collecting technique interview, observation and enquette. Data analysis, data qualitative before analysed to be turned into quantitative data in the form of scale. Each variable made to become five classificat pursuant to scale of likert. Data analysed descriptively to find supervation level, Structural Equation Model (SEM) to find internal and eksternal factor. So that desain model supervation with descriptive analysis. Result of research desain model and peripheral of supporter of effective supervation Village Credit Institution. The conclusion desain model supported by three sub system: sub system institute yield body supervisor of Village Credit Institution, sub system standardization and working procedure yield standard operating procedure supervisor of Village Credit Institution, sub system education and training yield supervisor professional of Village Credit Institution.

In Vitro Evaluation of Shear Bond Strength of Nanocomposites to Dentin

PubMed Central

Vellanki, Vinay Kumar; Shetty, Vikram K; Kushwah, Sudhanshu; Goyal, Geeta; Chandra, S.M. Sharath

2015-01-01

Aims: To compare the shear bond strength of nanocomposites to dentin using three different types of adhesive systems; and to test few specimens under Scanning Electron Microscope (SEM) for analysing whether the bond failure is adhesive or cohesive. Materials and Methods: Sixty human premolar teeth were selected and were randomly grouped, with 20 specimens in each group: group 1 - fluoride releasing dentin bonding agent; group 2 - antibacterial containing dentin bonding agent; and group 3 - one step conventional self etch adhesive. Each group was treated with its respective bonding agents, composite resin build up was done, and shear bond strengths were tested using Instron Universal testing machine. Few of the specimens were tested under SEM. Results: The results were statistically analysed using One-way ANOVA and paired t-test. It was observed that group 3 has the highest shear bond strength followed by group 2, and then group 1. Adhesive failures and mixed failures were most frequent types of failures as seen under SEM. Conclusion: Addition of antimicrobial agent decreases the bond strength of dentin bonding agent and addition of fluoride further decreases the bond strength. From SEM results it can be concluded that the zone of failure could not be defined and also that the failure mode was independent of the dentin bonding agent used. PMID:25738077

Comparing the Effectiveness of Polymer Debriding Devices Using a Porcine Wound Biofilm Model

PubMed Central

Wilkinson, Holly N.; McBain, Andrew J.; Stephenson, Christian; Hardman, Matthew J.

2016-01-01

Objective: Debridement to remove necrotic and/or infected tissue and promote active healing remains a cornerstone of contemporary chronic wound management. While there has been a recent shift toward less invasive polymer-based debriding devices, their efficacy requires rigorous evaluation. Approach: This study was designed to directly compare monofilament debriding devices to traditional gauze using a wounded porcine skin biofilm model with standardized application parameters. Biofilm removal was determined using a surface viability assay, bacterial counts, histological assessment, and scanning electron microscopy (SEM). Results: Quantitative analysis revealed that monofilament debriding devices outperformed the standard gauze, resulting in up to 100-fold greater reduction in bacterial counts. Interestingly, histological and morphological analyses suggested that debridement not only removed bacteria, but also differentially disrupted the bacterially-derived extracellular polymeric substance. Finally, SEM of post-debridement monofilaments showed structural changes in attached bacteria, implying a negative impact on viability. Innovation: This is the first study to combine controlled and defined debridement application with a biologically relevant ex vivo biofilm model to directly compare monofilament debriding devices. Conclusion: These data support the use of monofilament debriding devices for the removal of established wound biofilms and suggest variable efficacy towards biofilms composed of different species of bacteria. PMID:27867752

Disability and health-related quality-of-life 4 years after a severe traumatic brain injury: A structural equation modelling analysis.

PubMed

Azouvi, Philippe; Ghout, Idir; Bayen, Eleonore; Darnoux, Emmanuelle; Azerad, Sylvie; Ruet, Alexis; Vallat-Azouvi, Claire; Pradat-Diehl, Pascale; Aegerter, Philippe; Charanton, James; Jourdan, Claire

2016-01-01

To assess predictors and indicators of disability and quality-of-life 4 years after severe traumatic brain injury (TBI), using structural equation modelling (SEM). The PariS-TBI study is a longitudinal multi-centre inception cohort study of 504 patients with severe TBI. Among 245 survivors, 147 patients were evaluated upon 4-year follow-up, and 85 completed the full assessment. Two outcome measures were analysed separately using SEM: the Glasgow Outcome Scale-extended (GOS-E), to measure disability, and the QOLIBRI, to assess quality-of-life. Four groups of variables were entered in the model: demographics; injury severity; mood and cognitive impairments; somatic impairments. The GOS-E was directly significantly related to mood and cognition, injury severity, and somatic impairments. Age and education had an indirect effect, mediated by mood/cognition or somatic deficiencies. In contrast, the only direct predictor of QOLIBRI was mood and cognition. Age and somatic impairments had an indirect influence on the QOLIBRI. Although this study should be considered as explorative, it suggests that disability and quality-of-life were directly influenced by different factors. While disability appeared to result from an interaction of a wide range of factors, quality-of-life was solely directly related to psycho-cognitive factors.

Discopersicus n. gen., a New Member of the Family Tylenchidae Örley, 1880 with Detailed SEM Study on Two Known Species of the Genus Discotylenchus Siddiqi, 1980 (Nematoda; Tylenchidae) from Iran.

PubMed

Yaghoubi, Ali; Pourjam, Ebrahim; Álvarez-Ortega, Sergio; Liébanas, Gracia; Atighi, Mohammad Reza; Pedram, Majid

2016-09-01

Discopersicus iranicus n. gen., n. comb., previously described from Iran as a new species under the genus Discotylenchus , is illustrated using light microscope and scanning electron microscope (SEM) observations and further studied using molecular characters. SEM studies revealed the newly proposed genus has oblique amphidial apertures on the lateral sides of the lip region. SEM images are also provided for two species of Discotylenchus , namely D. discretus and D. brevicaudatus , as the first SEM study of the genus . These results confirmed longitudinal amphidial aperture type on lateral sides of the lip region in genus Discotylenchus , as noted by Siddiqi while erecting the genus with D. discretus as the type species . Molecular phylogenetic analyses using partial small subunit (SSU) and large subunit (LSU) rDNA sequences revealed the affinity of the genus Discopersicus n. gen. with members of the subfamily Boleodorinae, as supported by morphological characters (mainly, the oblique amphidial opening).

A structural equation model of soil metal bioavailability to earthworms: confronting causal theory and observations using a laboratory exposure to field-contaminated soils.

PubMed

Beaumelle, Léa; Vile, Denis; Lamy, Isabelle; Vandenbulcke, Franck; Gimbert, Frédéric; Hedde, Mickaël

2016-11-01

Structural equation models (SEM) are increasingly used in ecology as multivariate analysis that can represent theoretical variables and address complex sets of hypotheses. Here we demonstrate the interest of SEM in ecotoxicology, more precisely to test the three-step concept of metal bioavailability to earthworms. The SEM modeled the three-step causal chain between environmental availability, environmental bioavailability and toxicological bioavailability. In the model, each step is an unmeasured (latent) variable reflected by several observed variables. In an exposure experiment designed specifically to test this SEM for Cd, Pb and Zn, Aporrectodea caliginosa was exposed to 31 agricultural field-contaminated soils. Chemical and biological measurements used included CaC12-extractable metal concentrations in soils, free ion concentration in soil solution as predicted by a geochemical model, dissolved metal concentration as predicted by a semi-mechanistic model, internal metal concentrations in total earthworms and in subcellular fractions, and several biomarkers. The observations verified the causal definition of Cd and Pb bioavailability in the SEM, but not for Zn. Several indicators consistently reflected the hypothetical causal definition and could thus be pertinent measurements of Cd and Pb bioavailability to earthworm in field-contaminated soils. SEM highlights that the metals present in the soil solution and easily extractable are not the main source of available metals for earthworms. This study further highlights SEM as a powerful tool that can handle natural ecosystem complexity, thus participating to the paradigm change in ecotoxicology from a bottom-up to a top-down approach. Copyright © 2016 Elsevier B.V. All rights reserved.

Vector Autoregression, Structural Equation Modeling, and Their Synthesis in Neuroimaging Data Analysis

PubMed Central

Chen, Gang; Glen, Daniel R.; Saad, Ziad S.; Hamilton, J. Paul; Thomason, Moriah E.; Gotlib, Ian H.; Cox, Robert W.

2011-01-01

Vector autoregression (VAR) and structural equation modeling (SEM) are two popular brain-network modeling tools. VAR, which is a data-driven approach, assumes that connected regions exert time-lagged influences on one another. In contrast, the hypothesis-driven SEM is used to validate an existing connectivity model where connected regions have contemporaneous interactions among them. We present the two models in detail and discuss their applicability to FMRI data, and interpretational limits. We also propose a unified approach that models both lagged and contemporaneous effects. The unifying model, structural vector autoregression (SVAR), may improve statistical and explanatory power, and avoids some prevalent pitfalls that can occur when VAR and SEM are utilized separately. PMID:21975109

Scanning electron microscopic and X-ray micro analysis on tooth enamel exposed to alkaline agents.

PubMed

Taubee, Fabian; Steiniger, Frank; Nietzsche, Sandor; Norén, Jörgen G

2010-01-01

The background of this study comprises two clinical cases, where patients exposed to aerosols of an alkaline and surface active cleaning agent developed loss of enamel substance on their teeth, further resulting in loss of teeth and partially destroyed soft tissues. The alkaline cleaning agent consisted of potassium hydroxide and various surfactants. The purpose of this study was to investigate possible changes in morphology and composition in human teeth enamel exposed to alkaline solutions, by means of X-ray micro analysis (XRMA), FTIR-spectroscopic analyses and scanning electron microscopy (SEM). Extracted premolars, exposed to potassium hydroxide solutions and alkaline cleaning solution,were analyzed by means of XRMA and SEM. Enamel powder, exposed to cleaning solution, was analyzed by means of FTIR. The SEM analysis revealed an increased porosity of the enamel surface and partially loss of enamel substance after exposure to alkaline solutions. The XRMA analyses revealed a decrease in carbon concentration while phosphorous and calcium showed no marked changes. The FTIR analyses showed no significant changes in peak heights or peak positions for phosphate, carbonate or hydroxide. It was concluded that human teeth enamel exposed to alkaline solutions showed loss of organic substance, marked pores in enamel surface and loss of substance in the enamel surface.

The effect of service satisfaction and spiritual well-being on the quality of life of patients with schizophrenia.

PubMed

Lanfredi, Mariangela; Candini, Valentina; Buizza, Chiara; Ferrari, Clarissa; Boero, Maria E; Giobbio, Gian M; Goldschmidt, Nicoletta; Greppo, Stefania; Iozzino, Laura; Maggi, Paolo; Melegari, Anna; Pasqualetti, Patrizio; Rossi, Giuseppe; de Girolamo, Giovanni

2014-05-15

Quality of life (QOL) has been considered an important outcome measure in psychiatric research and determinants of QOL have been widely investigated. We aimed at detecting predictors of QOL at baseline and at testing the longitudinal interrelations of the baseline predictors with QOL scores at a 1-year follow-up in a sample of patients living in Residential Facilities (RFs). Logistic regression models were adopted to evaluate the association between WHOQoL-Bref scores and potential determinants of QOL. In addition, all variables significantly associated with QOL domains in the final logistic regression model were included by using the Structural Equation Modeling (SEM). We included 139 patients with a diagnosis of schizophrenia spectrum. In the final logistic regression model level of activity, social support, age, service satisfaction, spiritual well-being and symptoms' severity were identified as predictors of QOL scores at baseline. Longitudinal analyses carried out by SEM showed that 40% of QOL follow-up variability was explained by QOL at baseline, and significant indirect effects toward QOL at follow-up were found for satisfaction with services and for social support. Rehabilitation plans for people with schizophrenia living in RFs should also consider mediators of change in subjective QOL such as satisfaction with mental health services. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Cumulative childhood trauma and psychological maladjustment of sexually abused children in Korea: mediating effects of emotion regulation.

PubMed

Choi, Ji Young; Oh, Kyung Ja

2014-02-01

The purpose of the present study was to identify the mediating effects of emotion regulation on the association between cumulative childhood trauma and behavior problems in sexually abused children in Korea, using structural equation modeling (SEM). Data were collected on 171 children (ages 6-13 years) referred to a public counseling center for sexual abuse in Seoul, Korea. Cumulative childhood traumas were defined on the basis of number of traumas (physical abuse, witnessing domestic violence, neglect, traumatic separation from parent, and sexual abuse) and the severity and duration of traumas. Children were evaluated by their parents on emotion regulation using the Emotion Regulation Checklist and internalizing and externalizing behavior problems using the Korean-Child Behavior Checklist. SEM analyses confirmed the complete mediation model, in which emotion dysregulation fully mediates the relationship between cumulative childhood traumas and internalizing/externalizing behavior problems. These findings indicate that emotion regulation is an important mechanism that can explain the negative effects of cumulative childhood traumas and that there is a need to focus on emotion regulation in sexually abused children exposed to cumulative trauma. Copyright © 2013 Elsevier Ltd. All rights reserved.

Determinants of fast-food consumption. An application of the Theory of Planned Behaviour.

PubMed

Dunn, Kirsten I; Mohr, Philip; Wilson, Carlene J; Wittert, Gary A

2011-10-01

This study applied and extended the Theory of Planned Behaviour (TPB; Ajzen, 1988) in an examination of the variables influencing fast-food consumption in an Australian sample. Four hundred and four participants responded to items measuring TPB constructs and retrospective and prospective measures of fast-food consumption. Additional independent variables included: Consideration of Future Consequences (Strathman, Gleicher, Boninger, & Edwards, 1994), Fear of Negative Evaluation (Leary, 1983), and Self-Identification as a Healthy Eater Scale (Armitage & Conner, 1999a). Structural Equation Modeling (SEM) was used to examine predictors of consumption. SEM indicated that the TPB successfully predicted fast-food consumption. Factor analyses assisted in the definition of constructs that underlay attitudes towards fast foods. These constructs were included in an 'extended' TPB model which then provided a richer source of information regarding the nature of the variables influencing fast-food consumption. Findings suggest that fast-food consumption is influenced by specific referent groups as well as a general demand for meals that are tasty, satisfying, and convenient. These factors reflect immediate needs and appear to override concerns about longer-term health risks associated with fast food. Results are discussed in the context of possible applications. Copyright © 2011 Elsevier Ltd. All rights reserved.

Petrographic and petrological studies of lunar rocks. [from the Apollo 15 mission

NASA Technical Reports Server (NTRS)

Winzer, S. R.

1978-01-01

Thin sections and polished electron probe mounts of Apollo 15 glasscoated breccias 15255, 15286, 15466, and 15505 were examined optically and analyzed by sem/microprobe. Sections from breccias 15465 and 15466 were examined in detail, and chemical and mineralogical analyses of several larger lithic clasts, green glass, and partly crystallized green glass spheres are presented. Area analyses of 33 clasts from the above breccias were also done using the SEM/EDS system. Mineralogical and bulk chemical analyses of clasts from the Apollo 15 glass-coated breccias reveal a diverse set of potential rock types, including plutonic and extrusive igneous rocks and impact melts. Examination of the chemistry of the clasts suggests that many of these clasts, like those found in 61175, are impact melts. Their variability suggests formation by several small local impacts rather than by a large basin-forming event.

Does species diversity limit productivity in natural grassland communities?

USGS Publications Warehouse

Grace, J.B.; Anderson, T.M.; Smith, M.D.; Seabloom, E.; Andelman, S.J.; Meche, G.; Weiher, E.; Allain, L.K.; Jutila, H.; Sankaran, M.; Knops, J.; Ritchie, M.; Willig, M.R.

2007-01-01

Theoretical analyses and experimental studies of synthesized assemblages indicate that under particular circumstances species diversity can enhance community productivity through niche complementarity. It remains unclear whether this process has important effects in mature natural ecosystems where competitive feedbacks and complex environmental influences affect diversity-productivity relationships. In this study, we evaluated diversity-productivity relationships while statistically controlling for environmental influences in 12 natural grassland ecosystems. Because diversity-productivity relationships are conspicuously nonlinear, we developed a nonlinear structural equation modeling (SEM) methodology to separate the effects of diversity on productivity from the effects of productivity on diversity. Meta-analysis was used to summarize the SEM findings across studies. While competitive effects were readily detected, enhancement of production by diversity was not. These results suggest that the influence of small-scale diversity on productivity in mature natural systems is a weak force, both in absolute terms and relative to the effects of other controls on productivity. ?? 2007 Blackwell Publishing Ltd/CNRS.

Alginate-hydroxypropylcellulose hydrogel microbeads for alkaline phosphatase encapsulation.

PubMed

Karewicz, A; Zasada, K; Bielska, D; Douglas, T E L; Jansen, J A; Leeuwenburgh, S C G; Nowakowska, M

2014-01-01

There is a growing interest in using proteins as therapeutics agents. Unfortunately, they suffer from limited stability and bioavailability. We aimed to develop a new delivery system for proteins. ALP, a model protein, was successfully encapsulated in the physically cross-linked sodium alginate/hydroxypropylcellulose (ALG-HPC) hydrogel microparticles. The obtained objects had regular, spherical shape and a diameter of ∼4 µm, as confirmed by optical microscopy and SEM analysis. The properties of the obtained microbeads could be controlled by temperature and additional coating or crosslinking procedures. The slow, sustained release of ALP in its active form with no initial burst effect was observed for chitosan-coated microspheres at pH = 7.4 and 37 °C. Activity of ALP released from ALG/HPC microspheres was confirmed by the occurance of effectively induced mineralization. SEM and AFM images revealed formation of the interpenetrated three-dimensional network of mineral, originating from the microbeads' surfaces. FTIR and XRD analyses confirmed formation of hydroxyapatite.

A Miniaturized Variable Pressure Scanning Electron Microscope (MVP-SEM) for In-Situ Mars Surface Sample Analysis

NASA Technical Reports Server (NTRS)

Edmunson, J.; Gaskin, J. A.; Jerman, G. A.; Harvey, R. P.; Doloboff, I. J.; Neidholdt, E. L.

2016-01-01

The Miniaturized Variable Pressure Scanning Electron Microscope (MVP-SEM) project, funded by the NASA Planetary Instrument Concepts for the Advancement of Solar System Observations (PICASSO) Research Opportunities in Space and Earth Sciences (ROSES), will build upon previous miniaturized SEM designs and recent advancements in variable pressure SEM's to design and build a SEM to complete analyses of samples on the surface of Mars using the atmosphere as an imaging medium. This project is a collaboration between NASA Marshall Space Flight Center (MSFC), the Jet Propulsion Laboratory (JPL), electron gun and optics manufacturer Applied Physics Technologies, and small vacuum system manufacturer Creare. Dr. Ralph Harvery and environmental SEM (ESEM) inventor Dr. Gerry Danilatos serve as advisors to the team. Variable pressure SEMs allow for fine (nm-scale) resolution imaging and micron-scale chemical study of materials without sample preparation (e.g., carbon or gold coating). Charging of a sample is reduced or eliminated by the gas surrounding the sample. It is this property of ESEMs that make them ideal for locations where sample preparation is not yet feasible, such as the surface of Mars. In addition, the lack of sample preparation needed here will simplify the sample acquisition process and allow caching of the samples for future complementary payload use.

The advancement of the built environment research through employment of structural equation modeling (SEM)

NASA Astrophysics Data System (ADS)

Wasilah, S.; Fahmyddin, T.

2018-03-01

The employment of structural equation modeling (SEM) in research has taken an increasing attention in among researchers in built environment. There is a gap to understand the attributes, application, and importance of this approach in data analysis in built environment study. This paper intends to provide fundamental comprehension of SEM method in data analysis, unveiling attributes, employment and significance and bestow cases to assess associations amongst variables and constructs. The study uses some main literature to grasp the essence of SEM regarding with built environment research. The better acknowledgment of this analytical tool may assist the researcher in the built environment to analyze data under complex research questions and to test multivariate models in a single study.

Comparison of methods for the analysis of relatively simple mediation models.

PubMed

Rijnhart, Judith J M; Twisk, Jos W R; Chinapaw, Mai J M; de Boer, Michiel R; Heymans, Martijn W

2017-09-01

Statistical mediation analysis is an often used method in trials, to unravel the pathways underlying the effect of an intervention on a particular outcome variable. Throughout the years, several methods have been proposed, such as ordinary least square (OLS) regression, structural equation modeling (SEM), and the potential outcomes framework. Most applied researchers do not know that these methods are mathematically equivalent when applied to mediation models with a continuous mediator and outcome variable. Therefore, the aim of this paper was to demonstrate the similarities between OLS regression, SEM, and the potential outcomes framework in three mediation models: 1) a crude model, 2) a confounder-adjusted model, and 3) a model with an interaction term for exposure-mediator interaction. Secondary data analysis of a randomized controlled trial that included 546 schoolchildren. In our data example, the mediator and outcome variable were both continuous. We compared the estimates of the total, direct and indirect effects, proportion mediated, and 95% confidence intervals (CIs) for the indirect effect across OLS regression, SEM, and the potential outcomes framework. OLS regression, SEM, and the potential outcomes framework yielded the same effect estimates in the crude mediation model, the confounder-adjusted mediation model, and the mediation model with an interaction term for exposure-mediator interaction. Since OLS regression, SEM, and the potential outcomes framework yield the same results in three mediation models with a continuous mediator and outcome variable, researchers can continue using the method that is most convenient to them.

An examination of the path between recent sexual violence and sexually transmitted infections.

PubMed

von Sternberg, Kirk; Cardoso, Jodi Berger; Jun, Jina; Learman, Joy; Velasquez, Mary M

2012-01-01

Sexually transmitted infections (STIs) are among the most common infections in the United States and are particularly prevalent in survivors of sexual violence. The purpose of this study is to examine co-occurring risk factors for sexual violence and STIs including mental health, alcohol use, drug use, and multiple partners as intersecting pathways to STIs for women who experienced sexual abuse in the past year. Secondary analyses were conducted on cross-sectional data from women originally recruited as respondents for an epidemiologic survey funded by the Centers for Disease Control and Prevention (CDC): Project CHOICES. The survey was administered to 2,672 women in six settings: A large, urban jail and residential alcohol and drug treatment facilities (Texas); a gynecology clinic (Virginia); two primary care clinics (Virginia and Florida); and media solicitation (Florida). Women were included in the current study if they were fertile, sexually active, and not pregnant or trying to get pregnant (n = 1,183). Structural equation modeling (SEM) was used to test the conceptual path model between sexual violence and STI occurrence. In the SEM, there were no significant paths from mental health, alcohol severity, or drug use to STI occurrence contrary to the results of the initial bivariate analyses. Multiple sexual partners significantly mediated the relationship between sexual violence and STIs and between mental health and drug use and STIs. This study highlights the importance of providing effective treatment to survivors of sexual violence, which includes addressing risky sexual behaviors to reduce STI occurrence. Copyright © 2012 Jacobs Institute of Women's Health. Published by Elsevier Inc. All rights reserved.

IPS-Empress II inlay-retained fixed partial denture reinforced with zirconia bar: three-dimensional finite element and in-vitro studies.

PubMed

Kermanshah, Hamid; Geramy, Allahyar; Ebrahimi, Shahram Farzin; Bitaraf, Tahereh

2012-12-01

This study evaluated von Mises stress distribution, flexural strength and interface micrographs of IPS-Empress II (IPS) inlay-retained fixed partial dentures (IRFPD) reinforced with Zirconia bars (Zb). In the Finite element analysis, six three-dimensional models of IRFPD were designed using Solid Works 2006. Five models were reinforced with different Zb and a model without Zb was considered as a control. The bridges were loaded by 200 and 500 N forces at the middle of the pontic on the occlusal surface. Subsequently, von Mises stress and displacement of the models were evaluated along a defined path. In the experimental part, 21 bar shape specimens were fabricated from lithium disilicate and zirconia ceramic in three different designs. The zirconia-IPS interfaces and the fractured surfaces of flexural test were observed using SEM. In the connector area, von Mises stress and displacement of the models with Zb under a load of 500 N were decreased compared to the model without the Zb; however, this difference was not considerable at a load of 200 N. In the mesial connector, Von Mises stress and displacement was decreased from 12.5 Mpa for the control model tested at 500 N to 7.0 Mpa for the model with Zb and from 0.0050-0.0041 mm, respectively. SEM analyses showed that, before fracture, interfacial gaps were not observed along the interfaces, but initiated cracks propagated along the interfaces after flexural loading. IPS IRFPD reinforced by Zb can tolerate higher stresses while still functioning effectively and the interfaces may have desirable adaption.

Adolescents' relationship with God and internalizing adjustment over time: the moderating role of maternal religious coping.

PubMed

Goeke-Morey, Marcie C; Taylor, Laura K; Merrilees, Christine E; Shirlow, Peter; Cummings, E Mark

2014-12-01

A growing literature supports the importance of understanding the link between religiosity and youths' adjustment and development, but in the absence of rigorous, longitudinal designs, questions remain about the direction of effect and the role of family factors. This paper investigates the bidirectional association between adolescents' relationship with God and their internalizing adjustment. Results from 2-wave, SEM cross-lag analyses of data from 667 mother/adolescent dyads in Belfast, Northern Ireland (50% male, M age = 15.75 years old) supports a risk model suggesting that greater internalizing problems predict a weaker relationship with God 1 year later. Significant moderation analyses suggest that a stronger relationship with God predicted fewer depression and anxiety symptoms for youth whose mothers used more religious coping.

Adolescents’ relationship with God and internalizing adjustment over time: The moderating role of maternal religious coping

PubMed Central

Goeke-Morey, Marcie C.; Taylor, Laura K.; Merrilees, Christine E.; Shirlow, Peter; Cummings, E. Mark

2015-01-01

A growing literature supports the importance of understanding the link between religiosity and youths’ adjustment and development, but in the absence of rigorous, longitudinal designs, questions remain about the direction of effect and the role of family factors. This paper investigates the bi-directional association between adolescents’ relationship with God and their internalizing adjustment. Results from two-wave, SEM cross-lag analyses of data from 667 mother/adolescent dyads in Belfast, Northern Ireland (50% male, M age = 15.75 years old) supports a risk model suggesting that greater internalizing problems predicts a weaker relationship with God one year later. Significant moderation analyses suggest that a stronger relationship with God predicted fewer depression and anxiety symptoms for youth whose mothers used more religious coping. PMID:24955590

Validating the cross-cultural factor structure and invariance property of the Insomnia Severity Index: evidence based on ordinal EFA and CFA.

PubMed

Chen, Po-Yi; Yang, Chien-Ming; Morin, Charles M

2015-05-01

The purpose of this study is to examine the factor structure of the Insomnia Severity Index (ISI) across samples recruited from different countries. We tried to identify the most appropriate factor model for the ISI and further examined the measurement invariance property of the ISI across samples from different countries. Our analyses included one data set collected from a Taiwanese sample and two data sets obtained from samples in Hong Kong and Canada. The data set collected in Taiwan was analyzed with ordinal exploratory factor analysis (EFA) to obtain the appropriate factor model for the ISI. After that, we conducted a series of confirmatory factor analyses (CFAs), which is a special case of the structural equation model (SEM) that concerns the parameters in the measurement model, to the statistics collected in Canada and Hong Kong. The purposes of these CFA were to cross-validate the result obtained from EFA and further examine the cross-cultural measurement invariance of the ISI. The three-factor model outperforms other models in terms of global fit indices in Taiwan's population. Its external validity is also supported by confirmatory factor analyses. Furthermore, the measurement invariance analyses show that the strong invariance property between the samples from different cultures holds, providing evidence that the ISI results obtained in different cultures are comparable. The factorial validity of the ISI is stable in different populations. More importantly, its invariance property across cultures suggests that the ISI is a valid measure of the insomnia severity construct across countries. Copyright © 2014 Elsevier B.V. All rights reserved.

On the Progress of Scanning Transmission Electron Microscopy (STEM) Imaging in a Scanning Electron Microscope.

PubMed

Sun, Cheng; Müller, Erich; Meffert, Matthias; Gerthsen, Dagmar

2018-04-01

Transmission electron microscopy (TEM) with low-energy electrons has been recognized as an important addition to the family of electron microscopies as it may avoid knock-on damage and increase the contrast of weakly scattering objects. Scanning electron microscopes (SEMs) are well suited for low-energy electron microscopy with maximum electron energies of 30 keV, but they are mainly used for topography imaging of bulk samples. Implementation of a scanning transmission electron microscopy (STEM) detector and a charge-coupled-device camera for the acquisition of on-axis transmission electron diffraction (TED) patterns, in combination with recent resolution improvements, make SEMs highly interesting for structure analysis of some electron-transparent specimens which are traditionally investigated by TEM. A new aspect is correlative SEM, STEM, and TED imaging from the same specimen region in a SEM which leads to a wealth of information. Simultaneous image acquisition gives information on surface topography, inner structure including crystal defects and qualitative material contrast. Lattice-fringe resolution is obtained in bright-field STEM imaging. The benefits of correlative SEM/STEM/TED imaging in a SEM are exemplified by structure analyses from representative sample classes such as nanoparticulates and bulk materials.

Equivalence and Differences between Structural Equation Modeling and State-Space Modeling Techniques

ERIC Educational Resources Information Center

Chow, Sy-Miin; Ho, Moon-ho R.; Hamaker, Ellen L.; Dolan, Conor V.

2010-01-01

State-space modeling techniques have been compared to structural equation modeling (SEM) techniques in various contexts but their unique strengths have often been overshadowed by their similarities to SEM. In this article, we provide a comprehensive discussion of these 2 approaches' similarities and differences through analytic comparisons and…

Genome-wide association study of cognitive functions and educational attainment in UK Biobank (N=112 151)

PubMed Central

Davies, G; Marioni, R E; Liewald, D C; Hill, W D; Hagenaars, S P; Harris, S E; Ritchie, S J; Luciano, M; Fawns-Ritchie, C; Lyall, D; Cullen, B; Cox, S R; Hayward, C; Porteous, D J; Evans, J; McIntosh, A M; Gallacher, J; Craddock, N; Pell, J P; Smith, D J; Gale, C R; Deary, I J

2016-01-01

People's differences in cognitive functions are partly heritable and are associated with important life outcomes. Previous genome-wide association (GWA) studies of cognitive functions have found evidence for polygenic effects yet, to date, there are few replicated genetic associations. Here we use data from the UK Biobank sample to investigate the genetic contributions to variation in tests of three cognitive functions and in educational attainment. GWA analyses were performed for verbal–numerical reasoning (N=36 035), memory (N=112 067), reaction time (N=111 483) and for the attainment of a college or a university degree (N=111 114). We report genome-wide significant single-nucleotide polymorphism (SNP)-based associations in 20 genomic regions, and significant gene-based findings in 46 regions. These include findings in the ATXN2, CYP2DG, APBA1 and CADM2 genes. We report replication of these hits in published GWA studies of cognitive function, educational attainment and childhood intelligence. There is also replication, in UK Biobank, of SNP hits reported previously in GWA studies of educational attainment and cognitive function. GCTA-GREML analyses, using common SNPs (minor allele frequency>0.01), indicated significant SNP-based heritabilities of 31% (s.e.m.=1.8%) for verbal–numerical reasoning, 5% (s.e.m.=0.6%) for memory, 11% (s.e.m.=0.6%) for reaction time and 21% (s.e.m.=0.6%) for educational attainment. Polygenic score analyses indicate that up to 5% of the variance in cognitive test scores can be predicted in an independent cohort. The genomic regions identified include several novel loci, some of which have been associated with intracranial volume, neurodegeneration, Alzheimer's disease and schizophrenia. PMID:27046643

Bayesian Semiparametric Structural Equation Models with Latent Variables

ERIC Educational Resources Information Center

Yang, Mingan; Dunson, David B.

2010-01-01

Structural equation models (SEMs) with latent variables are widely useful for sparse covariance structure modeling and for inferring relationships among latent variables. Bayesian SEMs are appealing in allowing for the incorporation of prior information and in providing exact posterior distributions of unknowns, including the latent variables. In…

Imaging of surface spin textures on bulk crystals by scanning electron microscopy

NASA Astrophysics Data System (ADS)

Akamine, Hiroshi; Okumura, So; Farjami, Sahar; Murakami, Yasukazu; Nishida, Minoru

2016-11-01

Direct observation of magnetic microstructures is vital for advancing spintronics and other technologies. Here we report a method for imaging surface domain structures on bulk samples by scanning electron microscopy (SEM). Complex magnetic domains, referred to as the maze state in CoPt/FePt alloys, were observed at a spatial resolution of less than 100 nm by using an in-lens annular detector. The method allows for imaging almost all the domain walls in the mazy structure, whereas the visualisation of the domain walls with the classical SEM method was limited. Our method provides a simple way to analyse surface domain structures in the bulk state that can be used in combination with SEM functions such as orientation or composition analysis. Thus, the method extends applications of SEM-based magnetic imaging, and is promising for resolving various problems at the forefront of fields including physics, magnetics, materials science, engineering, and chemistry.

Test and Evaluation of TRUST: Tools for Recognizing Useful Signals of Trustworthiness

DTIC Science & Technology

2016-04-01

guaranteed, social exchange requires trust—the belief that others will follow through on their obligations. The model includes the beliefs that...current reflection could be measured based on properties of the skin, and (2) skin conductance response (SCR), where the fastest could be measured and...SEM prediction (H4d). The results of the LF HRV signals indicate the SEM model predicts distrust base on the experimental SS paradigm and SEM

Apatite Formation and Biocompatibility of a Low Young’s Modulus Ti-Nb-Sn Alloy Treated with Anodic Oxidation and Hot Water

PubMed Central

Tanaka, Hidetatsu; Mori, Yu; Noro, Atsushi; Kogure, Atsushi; Kamimura, Masayuki; Yamada, Norikazu; Hanada, Shuji; Masahashi, Naoya; Itoi, Eiji

2016-01-01

Ti-6Al-4V alloy is widely prevalent as a material for orthopaedic implants because of its good corrosion resistance and biocompatibility. However, the discrepancy in Young’s modulus between metal prosthesis and human cortical bone sometimes induces clinical problems, thigh pain and bone atrophy due to stress shielding. We designed a Ti-Nb-Sn alloy with a low Young’s modulus to address problems of stress disproportion. In this study, we assessed effects of anodic oxidation with or without hot water treatment on the bone-bonding characteristics of a Ti-Nb-Sn alloy. We examined surface analyses and apatite formation by SEM micrographs, XPS and XRD analyses. We also evaluated biocompatibility in experimental animal models by measuring failure loads with a pull-out test and by quantitative histomorphometric analyses. By SEM, abundant apatite formation was observed on the surface of Ti-Nb-Sn alloy discs treated with anodic oxidation and hot water after incubation in Hank’s solution. A strong peak of apatite formation was detected on the surface using XRD analyses. XPS analysis revealed an increase of the H2O fraction in O 1s XPS. Results of the pull-out test showed that the failure loads of Ti-Nb-Sn alloy rods treated with anodic oxidation and hot water was greater than those of untreated rods. Quantitative histomorphometric analyses indicated that anodic oxidation and hot water treatment induced higher new bone formation around the rods. Our findings indicate that Ti-Nb-Sn alloy treated with anodic oxidation and hot water showed greater capacity for apatite formation, stronger bone bonding and higher biocompatibility for osteosynthesis. Ti-Nb-Sn alloy treated with anodic oxidation and hot water treatment is a promising material for orthopaedic implants enabling higher osteosynthesis and lower stress disproportion. PMID:26914329

Towards a theory of PACS deployment: an integrative PACS maturity framework.

PubMed

van de Wetering, Rogier; Batenburg, Ronald

2014-06-01

Owing to large financial investments that go along with the picture archiving and communication system (PACS) deployments and inconsistent PACS performance evaluations, there is a pressing need for a better understanding of the implications of PACS deployment in hospitals. We claim that there is a gap in the research field, both theoretically and empirically, to explain the success of the PACS deployment and maturity in hospitals. Theoretical principles are relevant to the PACS performance; maturity and alignment are reviewed from a system and complexity perspective. A conceptual model to explain the PACS performance and a set of testable hypotheses are then developed. Then, structural equation modeling (SEM), i.e. causal modeling, is applied to validate the model and hypotheses based on a research sample of 64 hospitals that use PACS, i.e. 70 % of all hospitals in the Netherlands. Outcomes of the SEM analyses substantiate that the measurements of all constructs are reliable and valid. The PACS alignment-modeled as a higher-order construct of five complementary organizational dimensions and maturity levels-has a significant positive impact on the PACS performance. This result is robust and stable for various sub-samples and segments. This paper presents a conceptual model that explains how alignment in deploying PACS in hospitals is positively related to the perceived performance of PACS. The conceptual model is extended with tools as checklists to systematically identify the improvement areas for hospitals in the PACS domain. The holistic approach towards PACS alignment and maturity provides a framework for clinical practice.

The Relationship of Birth Order and Gender with Academic Standing and Substance Use Among Youth in Latin America.

PubMed

Horner, Pilar; Andrade, Fernando; Delva, Jorge; Grogan-Kaylor, Andy; Castillo, Marcela

2012-01-01

Alfred Adler attempted to understand how family affects youth outcomes by considering the order of when a child enters a family (Adler, 1964). Adler's theory posits that birth order formation impacts individuals. We tested Adler's birth order theory using data from a cross-sectional survey of 946 Chilean youths. We examined how birth order and gender are associated with drug use and educational outcomes using three different birth order research models including: (1) Expedient Research, (2) Adler's birth order position, and (3) Family Size theoretical models. Analyses were conducted with structural equation modeling (SEM). We conclude that birth order has an important relationship with substance use outcomes for youth but has differing effects for educational achievement across both birth order status and gender.

Three Approaches to Using Lengthy Ordinal Scales in Structural Equation Models: Parceling, Latent Scoring, and Shortening Scales

ERIC Educational Resources Information Center

Yang, Chongming; Nay, Sandra; Hoyle, Rick H.

2010-01-01

Lengthy scales or testlets pose certain challenges for structural equation modeling (SEM) if all the items are included as indicators of a latent construct. Three general approaches to modeling lengthy scales in SEM (parceling, latent scoring, and shortening) have been reviewed and evaluated. A hypothetical population model is simulated containing…

Adapting the Sport Education Model for Children with Disabilities

ERIC Educational Resources Information Center

Presse, Cindy; Block, Martin E.; Horton, Mel; Harvey, William J.

2011-01-01

The sport education model (SEM) has been widely used as a curriculum and instructional model to provide children with authentic and active sport experiences in physical education. In this model, students are assigned various roles to gain a deeper understanding of the sport or activity. This article provides a brief overview of the SEM and…

A Sandwich-Type Standard Error Estimator of SEM Models with Multivariate Time Series

ERIC Educational Resources Information Center

Zhang, Guangjian; Chow, Sy-Miin; Ong, Anthony D.

2011-01-01

Structural equation models are increasingly used as a modeling tool for multivariate time series data in the social and behavioral sciences. Standard error estimators of SEM models, originally developed for independent data, require modifications to accommodate the fact that time series data are inherently dependent. In this article, we extend a…

Maximum Likelihood Dynamic Factor Modeling for Arbitrary "N" and "T" Using SEM

ERIC Educational Resources Information Center

Voelkle, Manuel C.; Oud, Johan H. L.; von Oertzen, Timo; Lindenberger, Ulman

2012-01-01

This article has 3 objectives that build on each other. First, we demonstrate how to obtain maximum likelihood estimates for dynamic factor models (the direct autoregressive factor score model) with arbitrary "T" and "N" by means of structural equation modeling (SEM) and compare the approach to existing methods. Second, we go beyond standard time…

Modelling elderly patients' perception of the community pharmacist image when providing professional services.

PubMed

Sabater-Galindo, Marta; Sabater-Hernández, Daniel; Ruiz de Maya, Salvador; Gastelurrutia, Miguel Angel; Martínez-Martínez, Fernando; Benrimoj, Shalom I

2017-06-01

Professional pharmaceutical services may impact on patient's health behaviour as well as influence on patients' perceptions of the pharmacist image. The Health Belief Model predicts health-related behaviours using patients' beliefs. However, health beliefs (HBs) could transcend beyond predicting health behaviour and may have an impact on the patients' perceptions of the pharmacist image. This study objective was to develop and test a model that relates patients' HBs to patient's perception of the image of the pharmacist, and to assess if the provision of pharmacy services (Intervention group-IG) influences this perception compared to usual care (Control group). A qualitative study was undertaken and a questionnaire was created for the development of the model. The content, dimensions, validity and reliability of the questionnaire were pre-tested qualitatively and in a pilot mail survey. The reliability and validity of the proposed model were tested using Confirmatory Factor Analysis (CFA). Structural Equation Modelling (SEM) was used to explain relationships between dimensions of the final model and to analyse differences between groups. As a result, a final model was developed. CFA concluded that the model was valid and reliable (Goodness of Fit indices: x²(80) = 125.726, p = .001, RMSEA = .04, SRMR = .04, GFI = .997, NFI = .93, CFI = .974). SEM indicated that 'Perceived benefits' were significantly associated with 'Perceived Pharmacist Image' in the whole sample. Differences were found in the IG with also 'Self-efficacy' significantly influencing 'Perceived pharmacist image'. A model of patients' HBs related to their image of the pharmacist was developed and tested. When pharmacists deliver professional services, these services modify some patients' HBs that in turn influence public perception of the pharmacist.

Raman-in-SEM, a multimodal and multiscale analytical tool: performance for materials and expertise.

PubMed

Wille, Guillaume; Bourrat, Xavier; Maubec, Nicolas; Lahfid, Abdeltif

2014-12-01

The availability of Raman spectroscopy in a powerful analytical scanning electron microscope (SEM) allows morphological, elemental, chemical, physical and electronic analysis without moving the sample between instruments. This paper documents the metrological performance of the SEMSCA commercial Raman interface operated in a low vacuum SEM. It provides multiscale and multimodal analyses as Raman/EDS, Raman/cathodoluminescence or Raman/STEM (STEM: scanning transmission electron microscopy) as well as Raman spectroscopy on nanomaterials. Since Raman spectroscopy in a SEM can be influenced by several SEM-related phenomena, this paper firstly presents a comparison of this new tool with a conventional micro-Raman spectrometer. Then, some possible artefacts are documented, which are due to the impact of electron beam-induced contamination or cathodoluminescence contribution to the Raman spectra, especially with geological samples. These effects are easily overcome by changing or adapting the Raman spectrometer and the SEM settings and methodology. The deletion of the adverse effect of cathodoluminescence is solved by using a SEM beam shutter during Raman acquisition. In contrast, this interface provides the ability to record the cathodoluminescence (CL) spectrum of a phase. In a second part, this study highlights the interest and efficiency of the coupling in characterizing micrometric phases at the same point. This multimodal approach is illustrated with various issues encountered in geosciences. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dislocation, crystallite size distribution and lattice strain of magnesium oxide nanoparticles

NASA Astrophysics Data System (ADS)

Sutapa, I. W.; Wahid Wahab, Abdul; Taba, P.; Nafie, N. L.

2018-03-01

The oxide of magnesium nanoparticles synthesized using sol-gel method and analysis of the structural properties was conducted. The functional groups of nanoparticles has been analysed by Fourier Transform Infrared Spectroscopy (FT-IR). Dislocations, average size of crystal, strain, stress, the energy density of crystal, crystallite size distribution and morphologies of the crystals were determined based on X-ray diffraction profile analysis. The morphological of the crystal was analysed based on the image resulted from SEM analysis. The crystallite size distribution was calculated with the contention that the particle size has a normal logarithmic form. The most orientations of crystal were determined based on the textural crystal from diffraction data of X-ray diffraction profile analysis. FT-IR results showed the stretching vibration mode of the Mg-O-Mg in the range of 400.11-525 cm-1 as a broad band. The average size crystal of nanoparticles resulted is 9.21 mm with dislocation value of crystal is 0.012 nm-2. The strains, stress, the energy density of crystal are 1.5 x 10-4 37.31 MPa; 0.72 MPa respectively. The highest texture coefficient value of the crystal is 0.98. This result is supported by morphological analysis using SEM which shows most of the regular cubic-shaped crystals. The synthesis method is suitable for simple and cost-effective synthesis model of MgO nanoparticles.

International note: Prediction of mathematics work ethic and performance from behavioral, normative, and control beliefs among Qatari adolescents.

PubMed

Areepattamannil, Shaljan; Abdelfattah, Faisal; Mahasneh, Randa Ali; Khine, Myint Swe; Welch, Anita G; Melkonian, Michael; Al Nuaimi, Samira Ahmed

2016-01-01

Over half-a-million adolescents take part in each cycle of the Program for International Student Assessment (PISA). Yet often, researchers and policy makers across the globe tend to focus their attention primarily on the academic trajectories of adolescents hailing from highly successful education systems. Hence, a vast majority of the adolescent population who regionally and globally constitute the 'long tail of underachievement' often remain unnoticed and underrepresented in the growing literature on adolescents' academic trajectories. The present study, therefore, explored the relations of dispositions toward mathematics, subjective norms in mathematics, and perceived control of success in mathematics to mathematics work ethic as well as mathematics performance; and the mediational role of mathematics work ethic in the association between dispositional, normative, and control beliefs and mathematics performance among adolescents in one of the lowest performing education systems, Qatar. Structural equation modeling (SEM) analyses revealed that Qatari adolescents' dispositional, normative, and control beliefs about mathematics were significantly associated with their mathematics work ethic and mathematics performance, and mathematics work ethic significantly mediated the relationship between dispositional, normative, and control beliefs about mathematics and mathematics performance. However, multi-group SEM analyses indicated that these relationships were not invariant across the gender and the SES groups. Copyright © 2015 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

Structural Equations and Causal Explanations: Some Challenges for Causal SEM

ERIC Educational Resources Information Center

Markus, Keith A.

2010-01-01

One common application of structural equation modeling (SEM) involves expressing and empirically investigating causal explanations. Nonetheless, several aspects of causal explanation that have an impact on behavioral science methodology remain poorly understood. It remains unclear whether applications of SEM should attempt to provide complete…

Experimental sharp force injuries to ribs: Multimodal morphological and geometric morphometric analyses using micro-CT, macro photography and SEM.

PubMed

Komo, Larissa; Grassberger, Martin

2018-07-01

Tool marks on bones induced by knife blades can be analysed morphometrically in order to enable an allocation of the suspected "inflicting weapon" to the particular morphology of the bone lesions. Until now, geometric morphometrics has not been used to analyse the morphology of knife lesions on fleshed bones in detail. By using twelve experimental knives and a drop weight tower, stab/cut injuries were inflicted on untreated pig ribs. The morphology of the experimentally produced lesions was subsequently recorded with three imaging techniques (μCT, macro photography and SEM) and analysed with different morphometric software (Amira, tps and Morpheus). Based on the measured distances between the walls of the kerf marks, which corresponded to the thickness of the blade, one could conclude to the respective blade thickness with a deviation of max. ±0.35mm and match the injuries to the knives. With subsequent reanalysis after maceration, an average shrinkage factor up to 8.6% was observed. Among the three imaging techniques used in this study, μCT was the most accurate and efficient technique, particularly because it represented the only non-destructive modality to document injuries without maceration, even though μCT is more expensive and time-consuming as well as less accessible than a macro SLR-camera or a SEM. For optimal characterizations of the blades' and kerfs' shapes the software tps proofed to be the best choice. Accordingly, geometric morphometrics could serve as a tool in forensic investigations concerning kerf marks. Copyright © 2018 Elsevier B.V. All rights reserved.

Prescriptive Statements and Educational Practice: What Can Structural Equation Modeling (SEM) Offer?

ERIC Educational Resources Information Center

Martin, Andrew J.

2011-01-01

Longitudinal structural equation modeling (SEM) can be a basis for making prescriptive statements on educational practice and offers yields over "traditional" statistical techniques under the general linear model. The extent to which prescriptive statements can be made will rely on the appropriate accommodation of key elements of research design,…

A Note on Structural Equation Modeling Estimates of Reliability

ERIC Educational Resources Information Center

Yang, Yanyun; Green, Samuel B.

2010-01-01

Reliability can be estimated using structural equation modeling (SEM). Two potential problems with this approach are that estimates may be unstable with small sample sizes and biased with misspecified models. A Monte Carlo study was conducted to investigate the quality of SEM estimates of reliability by themselves and relative to coefficient…

The Schoolwide Enrichment Model: A Focus on Student Strengths and Interests

ERIC Educational Resources Information Center

Renzulli, Joseph S.; Renzulli, Sally Reis

2010-01-01

This article includes an introduction to the Schoolwide Enrichment Model (SEM), with its three components: a total talent portfolio for each child, curriculum differentiation and modification, and enrichment opportunities from the Enrichment Triad Model. Also included is a brief history of the SEM and a summary of 30 years of research underlying…

A Multilevel CFA-MTMM Model for Nested Structurally Different Methods

ERIC Educational Resources Information Center

Koch, Tobias; Schultze, Martin; Burrus, Jeremy; Roberts, Richard D.; Eid, Michael

2015-01-01

The numerous advantages of structural equation modeling (SEM) for the analysis of multitrait-multimethod (MTMM) data are well known. MTMM-SEMs allow researchers to explicitly model the measurement error, to examine the true convergent and discriminant validity of the given measures, and to relate external variables to the latent trait as well as…

Frequency domain finite-element and spectral-element acoustic wave modeling using absorbing boundaries and perfectly matched layer

NASA Astrophysics Data System (ADS)

Rahimi Dalkhani, Amin; Javaherian, Abdolrahim; Mahdavi Basir, Hadi

2018-04-01

Wave propagation modeling as a vital tool in seismology can be done via several different numerical methods among them are finite-difference, finite-element, and spectral-element methods (FDM, FEM and SEM). Some advanced applications in seismic exploration benefit the frequency domain modeling. Regarding flexibility in complex geological models and dealing with the free surface boundary condition, we studied the frequency domain acoustic wave equation using FEM and SEM. The results demonstrated that the frequency domain FEM and SEM have a good accuracy and numerical efficiency with the second order interpolation polynomials. Furthermore, we developed the second order Clayton and Engquist absorbing boundary condition (CE-ABC2) and compared it with the perfectly matched layer (PML) for the frequency domain FEM and SEM. In spite of PML method, CE-ABC2 does not add any additional computational cost to the modeling except assembling boundary matrices. As a result, considering CE-ABC2 is more efficient than PML for the frequency domain acoustic wave propagation modeling especially when computational cost is high and high-level absorbing performance is unnecessary.

A comparison using Faraday cups with 1013 Ω amplifiers and a secondary electron multiplier to measure Os isotopes by negative thermal ionization mass spectrometry.

PubMed

Wang, Guiqin; Sun, Tiantian; Xu, Jifeng

2017-10-15

According to the Johnson-Nyquist noise equation, the value of electron noise is proportional to the square root of the resistor value. This relationship gives a theoretical improvement of 100 in the signal/noise ratio by going from 10 11 Ω to 10 13 Ω amplifiers for Faraday detection in thermal ionization mass spectrometry (TIMS). We measured Os isotopes using static Faraday cups with 10 13 Ω amplifiers in negative thermal ionization mass spectrometry (NTIMS) and compared the results with those obtained with 10 11 Ω amplifiers and by peak-hopping on a single secondary electron multiplier (SEM). We analysed large loads of Os (1 μg) at a range of intensities of 187 OsO 3 (0.02-10 mV) in addition to small loads of Os (5-500 pg) to compare the results of the three methods. Using 10 13 Ω amplifiers, the long-term reproducibility determined from Merck Os was 187 Os/ 188 Os = 0.1211 ± 0.0086 and 0.120229 ± 0.000034 at 0.02 mV and 10 mV of 187 OsO 3 intensities. Meanwhile, the analysed JMC Os loadings of 5 and 500 pg showed 187 Os/ 188 Os = 0.10669 ± 0.00036 and 0.106807 ± 0.000023. In comparison, the values measured by the SEM were 187 Os/ 188 Os = 0.10704 ± 0.00056 and 0.10690 ± 0.00013. All errors are in 2 standard deviation (SD). Both the accuracy and the precision determined using the 10 13 Ω amplifiers and the SEM are identical when the Os amounts are within 10-50 pg. However, the former analysis time can be shortened by approximately two-thirds. The SEM measurement is still the most precise method for Os amounts <10 pg, but the analyses using 10 13 Ω amplifiers suggest they are significantly better than the SEM for Os amounts >50 pg. Copyright © 2017 John Wiley & Sons, Ltd.

Viscoelasticity and structure of blood clots generated in-vitro by rheometry: A comparison between human, horse, rat, and camel.

PubMed

Dibiasi, Christoph; Plewka, Jacek; Ploszczanski, Leon; Glanz, Veronika; Lichtenegger, Helga; Windberger, Ursula

2018-04-14

Although the coagulation system is evolutionary well preserved, profound species differences exist in viscoelastic as well as in common laboratory tests of coagulation. Evaluating differences in clot formation and material characterisation of clots of four mammalian species on macro-, micro- and nanoscales by the means of rheometry, scanning electron microscopy (SEM) and small angle x-ray scattering (SAXS). Blood samples were collected from healthy human volunteers, laboratory rats (HL/LE inbred strain), warmblood horses and dromedary camels. Clot formation was observed by oscillating shear rheometry until plateau formation of the shear storage modulus G', at which point selected clots were prepared for scanning electron microscopy. SEM images were analysed for fibre diameter and fractal dimension. Additionally, scattering profiles for plasma and whole blood samples were obtained with SAXS. Viscoelasticity of clots showed great interspecies variation: clots of rats and horses exhibited shorter clotting times and higher G' plateau values, when compared to human clots. Camel clots showed unique clotting characteristics with no G' plateau formation in the timeframe observed. Less differentiating features were found with SEM and SAXS, although the rat fibre network appears to be more convoluted and dense, which resulted in a higher fractal dimension. Clotting kinetic differs between the species, which is not only of clinical interest, but could also be an important finding for animal models of blood coagulation.

A Neglected Population: Media Consumption, Perceived Risk, and Fear of Crime Among International Students.

PubMed

Shi, Luzi

2018-03-01

The 4.5 million international students worldwide bring in multifold benefits to the advancement of culture, economy, and national security in education host countries. Surprisingly, few prior studies have explored international students' fear of crime, which may harm their mental and physical health and undermine their educational achievements. The current study aims to fill in this research void by investigating international students' fear of crime in line with the cultivation theoretical framework, which postulates that media consumption cultivates fear of crime. The analyses draw on a sample of 398 international students attending nine different public and private universities across the United States. Using structural equation modeling (SEM), I investigate the extent and correlates of students' fear of crime. The findings reveal that international students are more fearful in the United States than in their home countries. SEM results show that controlling for students' fear in their home countries, attention paid to crime news is positively related to fear in the United States, through perceived victimization risk. The SEM results also suggest that exposure to non-U.S. social media (e.g., WeChat and Weibo) is positively related to respondents' fear of crime, whereas exposure to U.S. social media (e.g., Facebook and Twitter) is not related to fear of crime. The current study highlights the importance of studying the impact of fear of crime and social media use on international students.

Early Adolescents' Emotional Well-Being in the Classroom: The Role of Personal and Contextual Assets.

PubMed

Oberle, Eva

2018-02-01

The objective was to predict early adolescents' emotional well-being from personal and contextual assets in the classroom. Emotional well-being is a key indicator of health. Aligned with the positive youth development (PYD) framework, a supportive classroom environment and positive relationships with teachers and peers were contextual assets in the present study; positive self-concept was a personal asset. The sample was 406 grade 4 to 7 public elementary school students from diverse backgrounds (mean = 11.27 years; SD = 0.89; 50% female). Data were self-, teacher-, and peer-reported. Structural equation modeling (SEM) analyses were used to evaluate model fit and identify significant pathways. SEM indicated a good model fit. Overall, 68% of variability in early adolescents' emotional well-being was explained. Positive self-concept directly predicted emotional well-being. Supportive classroom environment predicted emotional well-being directly and indirectly through increases in positive social relationships and self-concept. Positive social relationships predicted well-being only indirectly through positive self-concept. Contextual and personal assets are central for early adolescents' emotional well-being. The interrelation among assets needs to be considered when understanding, and ultimately promoting students' emotional well-being. The present findings extend previous research and inform school-based intervention and prevention programming and teacher professional development. © 2018, American School Health Association.

Do associations between employee self-reported organizational assessments and attitudinal outcomes change over time? An analysis of four Veterans Health Administration surveys using structural equation modelling.

PubMed

Das, Sonali; Chen, Ming-Hui; Warren, Nicholas; Hodgson, Michael

2011-12-01

This paper evaluates relationships between healthcare employees' perceptions of three hospital organizational constructs (Leadership, Support and Resources), and their assessment of two employee-related outcomes (employee satisfaction and retention) and two patient-related outcomes (patient satisfaction and quality of care). Using four all-employee surveys conducted by the Veterans Health Administration in the United States between 1997 and 2006, we examine the strength of these relationships and their changes over time. Exposure and outcome measures are employee-assessed in all the surveys. Because it can accommodate both latent and measured variables into the model, Structural Equation Modelling (SEM) is used to capture and quantify the relationship structure. The aim of the project is to identify possible intervention foci. The analyses revealed that employee-related outcomes are improved by increases in Leadership and Support, and, not surprisingly, the outcome variable of employee satisfaction reduced turnover intention. The employee assessed patient-related outcomes of satisfaction and quality of care were most improved by increases in Resources. Results also indicate that the three organizational constructs and the web of associations characterized by SEM underwent changes over the study period, perhaps in relation to changes in VHA policy emphases, changes in survey wording and other possible unmeasured factors. Copyright © 2010 John Wiley & Sons, Ltd.

Spatial modeling on the upperstream of the Citarum watershed: An application of geoinformatics

NASA Astrophysics Data System (ADS)

Ningrum, Windy Setia; Widyaningsih, Yekti; Indra, Tito Latif

2017-03-01

The Citarum watershed is the longest and the largest watershed in West Java, Indonesia, located at 106°51'36''-107°51' E and 7°19'-6°24'S across 10 districts, and serves as the water supply for over 15 million people. In this area, the water criticality index is concerned to reach the balance between water supply and water demand, so that in the dry season, the watershed is still able to meet the water needs of the society along the Citarum river. The objective of this research is to evaluate the water criticality index of Citarum watershed area using spatial model to overcome the spatial dependencies in the data. The result of Lagrange multiplier diagnostics for spatial dependence results are LM-err = 34.6 (p-value = 4.1e-09) and LM-lag = 8.05 (p-value = 0.005), then modeling using Spatial Lag Model (SLM) and Spatial Error Model (SEM) were conducted. The likelihood ratio test show that both of SLM dan SEM model is better than OLS model in modeling water criticality index in Citarum watershed. The AIC value of SLM and SEM model are 78.9 and 51.4, then the SEM model is better than SLM model in predicting water criticality index in Citarum watershed.

Self-expandable Metallic Stents Contribute to Reducing Perioperative Complications in Colorectal Cancer Patients with Acute Obstruction.

PubMed

Furuke, Hirotaka; Komatsu, Shuhei; Ikeda, Jun; Tanaka, Sachie; Kumano, Tatsuya; Imura, Ken-Ichiro; Shimomura, Katsumi; Taniguchi, Fumihiro; Ueshima, Yasuo; Takashina, Ken-Ichiro; Lee, Chol Joo; Deguchi, Eiichi; Ikeda, Eito; Otsuji, Eigo; Shioaki, Yasuhiro

2018-03-01

The self-expandable metallic stent (SEMS) is an excellent non-invasive tool for emergent bowel obstruction. This study was designed to evaluate the clinical usefulness of the SEMS for avoiding perioperative complications. We analyzed a total of 47 consecutive patients who had a bowel obstruction due to colorectal cancer at initial diagnosis between 2012 and 2017 from hospital records. Perioperative complications occurred in 30% (14/47) of patients. Univariate and multivariate logistic regression analyses identified an age of more than 75 years [p=0.037, OR=6.84 (95% CI=1.11-41.6)] and the absence of an SEMS treatment [p=0.028, OR=18.5 (95% CI=1.36-250.0)] as independent risk factors for perioperative complications. Pneumonia (12.7% (6/47)) was the most common complication. There were no pneumonia patients (0% (0/15)) who were treated with the SEMS. In contrast to patients with the non-SEMS treatment, 18.7% (6/32) of all patients and 35.7% (5/14) of elderly patients had pneumonia. The SEMS is a safe and effective treatment for avoiding perioperative complications, particularly pneumonia, and may be a crucial strategy in elderly patients with acute obstruction due to colorectal cancer. Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

Surgery on spinal epidural metastases (SEM) in renal cell carcinoma: a plea for a new paradigm.

PubMed

Bakker, Nicolaas A; Coppes, Maarten H; Vergeer, Rob A; Kuijlen, Jos M A; Groen, Rob J M

2014-09-01

Prediction models for outcome of decompressive surgical resection of spinal epidural metastases (SEM) have in common that they have been developed for all types of SEM, irrespective of the type of primary tumor. It is our experience in clinical practice, however, that these models often fail to accurately predict outcome in the individual patient. To investigate whether decision making could be optimized by applying tumor-specific prediction models. For the proof of concept, we analyzed patients with SEM from renal cell carcinoma that we have operated on. Retrospective chart analysis 2006 to 2012. Twenty-one consecutive patients with symptomatic SEM of renal cell carcinoma. Predictive factors for survival. Next to established predictive factors for survival, we analyzed the predictive value of the Motzer criteria in these patients. The Motzer criteria comprise a specific and validated risk model for survival in patients with renal cell carcinoma. After multivariable analysis, only Motzer intermediate (hazard ratio [HR] 17.4, 95% confidence interval [CI] 1.82-166, p=.01) and high risk (HR 39.3, 95% CI 3.10-499, p=.005) turned out to be significantly associated with survival in patients with renal cell carcinoma that we have operated on. In this study, we have demonstrated that decision making could have been optimized by implementing the Motzer criteria next to established prediction models. We, therefore, suggest that in future, in patients with SEM from renal cell carcinoma, the Motzer criteria are also taken into account. Copyright © 2014 Elsevier Inc. All rights reserved.

Spatially explicit modeling in ecology: A review

USGS Publications Warehouse

DeAngelis, Donald L.; Yurek, Simeon

2017-01-01

The use of spatially explicit models (SEMs) in ecology has grown enormously in the past two decades. One major advancement has been that fine-scale details of landscapes, and of spatially dependent biological processes, such as dispersal and invasion, can now be simulated with great precision, due to improvements in computer technology. Many areas of modeling have shifted toward a focus on capturing these fine-scale details, to improve mechanistic understanding of ecosystems. However, spatially implicit models (SIMs) have played a dominant role in ecology, and arguments have been made that SIMs, which account for the effects of space without specifying spatial positions, have an advantage of being simpler and more broadly applicable, perhaps contributing more to understanding. We address this debate by comparing SEMs and SIMs in examples from the past few decades of modeling research. We argue that, although SIMs have been the dominant approach in the incorporation of space in theoretical ecology, SEMs have unique advantages for addressing pragmatic questions concerning species populations or communities in specific places, because local conditions, such as spatial heterogeneities, organism behaviors, and other contingencies, produce dynamics and patterns that usually cannot be incorporated into simpler SIMs. SEMs are also able to describe mechanisms at the local scale that can create amplifying positive feedbacks at that scale, creating emergent patterns at larger scales, and therefore are important to basic ecological theory. We review the use of SEMs at the level of populations, interacting populations, food webs, and ecosystems and argue that SEMs are not only essential in pragmatic issues, but must play a role in the understanding of causal relationships on landscapes.

Development of uncertainty-based work injury model using Bayesian structural equation modelling.

PubMed

Chatterjee, Snehamoy

2014-01-01

This paper proposed a Bayesian method-based structural equation model (SEM) of miners' work injury for an underground coal mine in India. The environmental and behavioural variables for work injury were identified and causal relationships were developed. For Bayesian modelling, prior distributions of SEM parameters are necessary to develop the model. In this paper, two approaches were adopted to obtain prior distribution for factor loading parameters and structural parameters of SEM. In the first approach, the prior distributions were considered as a fixed distribution function with specific parameter values, whereas, in the second approach, prior distributions of the parameters were generated from experts' opinions. The posterior distributions of these parameters were obtained by applying Bayesian rule. The Markov Chain Monte Carlo sampling in the form Gibbs sampling was applied for sampling from the posterior distribution. The results revealed that all coefficients of structural and measurement model parameters are statistically significant in experts' opinion-based priors, whereas, two coefficients are not statistically significant when fixed prior-based distributions are applied. The error statistics reveals that Bayesian structural model provides reasonably good fit of work injury with high coefficient of determination (0.91) and less mean squared error as compared to traditional SEM.

Reliability of Summed Item Scores Using Structural Equation Modeling: An Alternative to Coefficient Alpha

ERIC Educational Resources Information Center

Green, Samuel B.; Yang, Yanyun

2009-01-01

A method is presented for estimating reliability using structural equation modeling (SEM) that allows for nonlinearity between factors and item scores. Assuming the focus is on consistency of summed item scores, this method for estimating reliability is preferred to those based on linear SEM models and to the most commonly reported estimate of…

Structural Equation Modeling (SEM) for Satisfaction and Dissatisfaction Ratings; Multiple Group Invariance Analysis across Scales with Different Response Format

ERIC Educational Resources Information Center

Mazaheri, Mehrdad; Theuns, Peter

2009-01-01

The current study evaluates three hypothesized models on subjective well-being, comprising life domain ratings (LDR), overall satisfaction with life (OSWL), and overall dissatisfaction with life (ODWL), using structural equation modeling (SEM). A sample of 1,310 volunteering students, randomly assigned to six conditions, rated their overall life…

Comparing Indirect Effects in SEM: A Sequential Model Fitting Method Using Covariance-Equivalent Specifications

ERIC Educational Resources Information Center

Chan, Wai

2007-01-01

In social science research, an indirect effect occurs when the influence of an antecedent variable on the effect variable is mediated by an intervening variable. To compare indirect effects within a sample or across different samples, structural equation modeling (SEM) can be used if the computer program supports model fitting with nonlinear…

Self-Concealment, Social Network Sites Usage, Social Appearance Anxiety, Loneliness of High School Students: A Model Testing

ERIC Educational Resources Information Center

Dogan, Ugur; Çolak, Tugba Seda

2016-01-01

This study was tested a model for explain to social networks sites (SNS) usage with structural equation modeling (SEM). Using SEM on a sample of 475 high school students (35% male, 65% female) students, model was investigated the relationship between self-concealment, social appearance anxiety, loneliness on SNS such as Twitter and Facebook usage.…

The effectiveness of manual and mechanical instrumentation for the retreatment of three different root canal filling materials.

PubMed

Somma, Francesco; Cammarota, Giuseppe; Plotino, Gianluca; Grande, Nicola M; Pameijer, Cornelis H

2008-04-01

The aim of this study was to compare the effectiveness of the Mtwo R (Sweden & Martina, Padova, Italy), ProTaper retreatment files (Dentsply-Maillefer, Ballaigues, Switzerland), and a Hedström manual technique in the removal of three different filling materials (gutta-percha, Resilon [Resilon Research LLC, Madison, CT], and EndoRez [Ultradent Products Inc, South Jordan, UT]) during retreatment. Ninety single-rooted straight premolars were instrumented and randomly divided into 9 groups of 10 teeth each (n = 10) with regards to filling material and instrument used. For all roots, the following data were recorded: procedural errors, time of retreatment, apically extruded material, canal wall cleanliness through optical stereomicroscopy (OSM), and scanning electron microscopy (SEM). A linear regression analysis and three logistic regression analyses were performed to assess the level of significance set at p = 0.05. The results indicated that the overall regression models were statistically significant. The Mtwo R, ProTaper retreatment files, and Resilon filling material had a positive impact in reducing the time for retreatment. Both ProTaper retreatment files and Mtwo R showed a greater extrusion of debris. For both OSM and SEM logistic regression models, the root canal apical third had the greatest impact on the score values. EndoRez filling material resulted in cleaner root canal walls using OSM analysis, whereas Resilon filling material and both engine-driven NiTi rotary techniques resulted in less clean root canal walls according to SEM analysis. In conclusion, all instruments left remnants of filling material and debris on the root canal walls irrespective of the root filling material used. Both the engine-driven NiTi rotary systems proved to be safe and fast devices for the removal of endodontic filling material.

Examining the mediating role of cancer-related problems on spirituality and self-rated health among African American cancer survivors: a report from the American Cancer Society's Studies of Cancer Survivors-II.

PubMed

Best, Alicia L; Alcaraz, Kassandra I; McQueen, Amy; Cooper, Dexter L; Warren, Rueben C; Stein, Kevin

2015-09-01

African American (AA) cancer survivors report poorer self-rated health (SRH) compared to other racial/ethnic groups. Spirituality is often linked to positive health outcomes, with AAs reporting greater levels of spirituality. This study examined the potential mediating role of cancer-related problems in the relationship between spirituality and SRH among AA cancer survivors compared to non-African American (non-AA) survivors. We analyzed data on 9006 adult cancer survivors from the American Cancer Society's Study of Cancer Survivors-II. Preliminary analyses compared characteristics of AAs and non-AAs and identified significant covariates of SRH. We tested a path model using multi-group structural equation modeling (SEM), and then examined race as a moderator. Of the three domains of spirituality assessed, AAs had higher levels of peace (p < .001) and faith (p < .001), but not meaning, compared to non-AAs; and of four domains of cancer-related problems assessed, AAs had greater physical distress (p < .001), emotional distress (p < .001), and employment/finance problems (p < .001), but not fear of recurrence. In SEM analyses adjusting for number of comorbidities and income, race moderated the impact of spirituality and cancer-related problems on SRH. Specifically, spirituality had significantly stronger associations with cancer-related problems among AAs than non-AAs. Spirituality was positively associated with all four domains of cancer-related problems, but only physical distress was associated with SRH among AAs. The negative effects of physical distress may attenuate the positive effects of spirituality on AA's SRH. Future studies should consider racial/ethnic differences in the determinants and conceptualization of SRH, which is a known predictor of survival. Copyright © 2014 John Wiley & Sons, Ltd.

Surface remineralization potential of casein phosphopeptide-amorphous calcium phosphate on enamel eroded by cola-drinks: An in-situ model study.

PubMed

Grewal, Navneet; Kudupudi, Vinod; Grewal, Sukrit

2013-07-01

The aim of this study was to investigate the remineralization potential of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on enamel eroded by cola drinks. A total of 30 healthy subjects were selected from a random sample of 1200 children and divided into two groups of 15 each wherein calcium and phosphorus analyses and scanning electron microscope (SEM) analysis was carried out to investigate the remineralization of enamel surface. A total of 30 non-carious premolar teeth were selected from the human tooth bank (HTB) to prepare the in-situ appliance. Three enamel slabs were prepared from the same. One enamel slab was used to obtain baseline values and the other two were embedded into the upper palatal appliances prepared on the subjects' maxillary working model. The subjects wore the appliance after which 30 ml cola drink exposure was given. After 15 days, the slabs were removed and subjected to respective analysis. Means of all the readings of soluble calcium and phosphorous levels at baseline,post cola-drink exposure and post cpp-acp application were subjected to statistical analysis SPSS11.5 version. Comparison within groups and between groups was carried out using ANOVA and F-values at 1% level of significance. Decrease in calcium solubility of enamel in the CPP-ACP application group as compared to post-cola drink exposure group (P < 0.05) was seen. Distinctive change in surface topography of enamel in the post-CPP-ACP application group as compared to post-cola drink exposure group was observed. CPP-ACP significantly promoted remineralization of enamel eroded by cola drinks as revealed by significant morphological changes seen in SEM magnification and spectrophotometric analyses.

Rasch analyses of the Activities-specific Balance Confidence Scale with individuals 50 years and older with lower limb amputations

PubMed Central

Sakakibara, Brodie M.; Miller, William C.; Backman, Catherine L.

2012-01-01

Objective To explore shortened response formats for use with the Activities-specific Balance Confidence scale and then: 1) evaluate the unidimensionality of the scale; 2) evaluate the item difficulty; 3) evaluate the scale for redundancy and content gaps; and 4) evaluate the item standard error of measurement (SEM) and internal consistency reliability among aging individuals (≥50 years) with a lower-limb amputation living in the community. Design Secondary analysis of cross-sectional survey and chart review data. Setting Out-patient amputee clinics, Ontario, Canada. Participants Four hundred forty eight community living adults, at least 50 years old (mean = 68 years), who have used a prosthesis for at least 6 months for a major unilateral lower limb amputation. Three hundred twenty five (72.5%) were men. Intervention N/a Main Outcome Measure(s) Activities-specific Balance Confidence Scale. Results A 5-option response format outperformed 4- and 6-option formats. Factor analyses confirmed a unidimensional scale. The distance between response options is not the same for all items on the scale, evident by the Partial Credit Model (PCM) having a better fit to the data than the Rating Scale Model. Two items, however, did not fit the PCM within statistical reason. Revising the wording of the two items may resolve the misfit, and improve the construct validity and lower the SEM. Overall, the difficulty of the scale’s items is appropriate for use with aging individuals with lower-limb amputation, and is most reliable (Cronbach ∝ = 0.94) for use with individuals with moderately low balance confidence levels. Conclusions The ABC-scale with a simplified 5-option response format is a valid and reliable measure of balance confidence for use with individuals aging with a lower limb amputation. PMID:21704978

The Role of Sexually Explicit Material (SEM) in the Sexual Development of Black Young Same-Sex-Attracted Men

PubMed Central

Morgan, Anthony; Ogunbajo, Adedotun; Trent, Maria; Harper, Gary W.; Fortenberry, J. Dennis

2015-01-01

Sexually explicit material (SEM) (including Internet, video, and print) may play a key role in the lives of Black same-sex sexually active youth by providing the only information to learn about sexual development. There is limited school-and/or family-based sex education to serve as models for sexual behaviors for Black youth. We describe the role SEM plays in the sexual development of a sample of Black same-sex attracted (SSA) young adolescent men ages 15–19. Adolescents recruited from clinics, social networking sites, and through snowball sampling were invited to participate in a 90-min, semi-structured qualitative interview. Most participants described using SEM prior to their first same-sex sexual experience. Participants described using SEM primarily for sexual development, including learning about sexual organs and function, the mechanics of same-gender sex, and to negotiate one’s sexual identity. Secondary functions were to determine readiness for sex; to learn about sexual performance, including understanding sexual roles and responsibilities (e.g., “top” or “bottom”); to introduce sexual performance scripts; and to develop models for how sex should feel (e.g., pleasure and pain). Youth also described engaging in sexual behaviors (including condom non-use and/or swallowing ejaculate) that were modeled on SEM. Comprehensive sexuality education programs should be designed to address the unmet needs of young, Black SSA young men, with explicit focus on sexual roles and behaviors that may be inaccurately portrayed and/or involve sexual risk-taking (such as unprotected anal intercourse and swallowing ejaculate) in SEM. This work also calls for development of Internet-based HIV/STI prevention strategies targeting young Black SSA men who maybe accessing SEM. PMID:25677334

Efficacy of terbinafine compared to lanoconazole and luliconazole in the topical treatment of dermatophytosis in a guinea pig model.

PubMed

Ghannoum, M A; Long, L; Kim, H G; Cirino, A J; Miller, A R; Mallefet, P

2010-05-01

The in vivo efficacy of terbinafine was compared to lanoconazole and luliconazole in the topical treatment of dermatophytosis caused by Trichophyton mentagrophytes using a guinea pig model. Topical antifungal treatment commenced three days post-infection, and each agent was applied once daily for seven consecutive days. Upon completion of the treatment period, evaluations of clinical and mycological efficacies were performed, as was scanning electron microscopy (SEM) analyses. Data showed that while all tested antifungals demonstrated significant mycological efficacy in terms of eradicating the fungi over untreated control, terbinafine and luliconazole showed superior clinical efficacy compared to lanoconazole (P-values < 0.001 & 0.003, respectively). Terbinafine demonstrated the highest clinical percent efficacy. SEM analysis revealed hairs from terbinafine and lanoconazole-treated animals had near complete clearance of fungi, while samples from luliconazole-treated animals were covered with debris and few conidia. This study demonstrates that, in general, terbinafine possessed similar efficacy to lanoconazole and luliconazole in the treatment of dermatophytosis. Terbinafine tended to have superior clinical efficacy compared to the azoles tested, although this difference was not statistically significant against luliconazole. This apparent superiority may be due to the fungicidal activity of terbinafine compared to the fungistatic effect of the other two drugs.

Fungal-Induced Deterioration of Mural Paintings: In Situ and Mock-Model Microscopy Analyses.

PubMed

Unković, Nikola; Grbić, Milica Ljaljević; Stupar, Miloš; Savković, Željko; Jelikić, Aleksa; Stanojević, Dragan; Vukojević, Jelena

2016-04-01

Fungal deterioration of frescoes was studied in situ on a selected Serbian church, and on a laboratory model, utilizing standard and newly implemented microscopy techniques. Scanning electron microscopy (SEM) with energy-dispersive X-ray confirmed the limestone components of the plaster. Pigments used were identified as carbon black, green earth, iron oxide, ocher, and an ocher/cinnabar mixture. In situ microscopy, applied via a portable microscope ShuttlePix P-400R, proved very useful for detection of invisible micro-impairments and hidden, symptomless, microbial growth. SEM and optical microscopy established that observed deterioration symptoms, predominantly discoloration and pulverization of painted layers, were due to bacterial filaments and fungal hyphal penetration, and formation of a wide range of fungal structures (i.e., melanized hyphae, chlamydospores, microcolonial clusters, Cladosporium-like conidia, and Chaetomium perithecia and ascospores). The all year-round monitoring of spontaneous and induced fungal colonization of a "mock painting" in controlled laboratory conditions confirmed the decisive role of humidity level (70.18±6.91% RH) in efficient colonization of painted surfaces, as well as demonstrated increased bioreceptivity of painted surfaces to fungal colonization when plant-based adhesives (ilinocopie, murdent), compared with organic adhesives of animal origin (bone glue, egg white), are used for pigment sizing.

Stressful work environment and wellbeing: What comes first?

PubMed

Elovainio, Marko; Heponiemi, Tarja; Jokela, Markus; Hakulinen, Christian; Presseau, Justin; Aalto, Anna-Mari; Kivimäki, Mika

2015-07-01

The association between the psychosocial work environment, including job demands, job control, and organizational justice, and employee wellbeing has been well established. However, the exposure to adverse work environments is typically measured only using self-reported measures that are vulnerable to reporting bias, and thus any associations found may be explained by reverse causality. Using linear regression models and cross-lagged structural equation modeling (SEM), we tested the direction of the association between established job stress models (job demand control and organizational justice models) and 3 wellbeing indicators (psychological distress, sleeping problems, and job satisfaction) among 1524 physicians in a 4-year follow-up. Results from the longitudinal cross-lagged analyses showed that the direction of the association was from low justice to decreasing wellbeing rather than the reverse. Although the pattern was similar in job demands and job control, a reciprocal association was found between job control and psychological distress. (c) 2015 APA, all rights reserved).

The Relationship of Birth Order and Gender with Academic Standing and Substance Use Among Youth in Latin America

PubMed Central

Horner, Pilar; Andrade, Fernando; Delva, Jorge; Grogan-Kaylor, Andy; Castillo, Marcela

2012-01-01

Alfred Adler attempted to understand how family affects youth outcomes by considering the order of when a child enters a family (Adler, 1964). Adler’s theory posits that birth order formation impacts individuals. We tested Adler’s birth order theory using data from a cross-sectional survey of 946 Chilean youths. We examined how birth order and gender are associated with drug use and educational outcomes using three different birth order research models including: (1) Expedient Research, (2) Adler’s birth order position, and (3) Family Size theoretical models. Analyses were conducted with structural equation modeling (SEM). We conclude that birth order has an important relationship with substance use outcomes for youth but has differing effects for educational achievement across both birth order status and gender. PMID:22707916

Friendship, perceived mattering and happiness: a study of American and Turkish college students.

PubMed

Demir, Melikşah; Ozen, Ayça; Doğan, Aysun

2012-01-01

Although it is well established that friendship is a consistent correlate of happiness, less is known about how friendship experiences might promote happiness. The current investigation addressed this gap by testing a mediational model proposing that perceived mattering explains the association of friendship quality with happiness among college students in Turkey and the United States. An alternative model suggesting friendship quality as the mediator was also tested to enhance confidence in the proposed model. SEM analyses revealed that perceived mattering mediated the association of friendship with happiness only in the American sample. In the Turkish sample, friendship quality mediated the association between mattering and happiness. Findings highlight the importance of cross-cultural research and suggest that the underlying processes and psychological mechanisms related to the friendship-happiness link might be different in different cultures.

Scanning electron microscopy of bone: instrument, specimen, and issues.

PubMed

Boyde, A; Jones, S J

1996-02-01

There are many ways available now to maximise and analyse the information that can be obtained on the structure and constitution of bone using SEM. This paper considers a range of methods and the problems that arise relating to instrumentation and methodology as they apply to the use of SEM in the study of bone. In addition to the review content, some novel technical approaches to the SEM of bone are considered here for the first time; these include low kV imaging for the detection of new surface bone packets (and residual demineralized matrix after resorption), low kV BSE imaging of uncoated, embedded, and unembedded samples, environmental SEM for the study of wet tissue, low distortion, very low magnification imaging for the study of cancellous bone architecture, the use of multiple detectors for fast electrons in improving the imaging of porous samples, and high resolution, low voltage imaging for the study of collagen degradation during bone resorption.

Dealing with Multiple Solutions in Structural Vector Autoregressive Models.

PubMed

Beltz, Adriene M; Molenaar, Peter C M

2016-01-01

Structural vector autoregressive models (VARs) hold great potential for psychological science, particularly for time series data analysis. They capture the magnitude, direction of influence, and temporal (lagged and contemporaneous) nature of relations among variables. Unified structural equation modeling (uSEM) is an optimal structural VAR instantiation, according to large-scale simulation studies, and it is implemented within an SEM framework. However, little is known about the uniqueness of uSEM results. Thus, the goal of this study was to investigate whether multiple solutions result from uSEM analysis and, if so, to demonstrate ways to select an optimal solution. This was accomplished with two simulated data sets, an empirical data set concerning children's dyadic play, and modifications to the group iterative multiple model estimation (GIMME) program, which implements uSEMs with group- and individual-level relations in a data-driven manner. Results revealed multiple solutions when there were large contemporaneous relations among variables. Results also verified several ways to select the correct solution when the complete solution set was generated, such as the use of cross-validation, maximum standardized residuals, and information criteria. This work has immediate and direct implications for the analysis of time series data and for the inferences drawn from those data concerning human behavior.

Gallic acid/hydroxypropyl-β-cyclodextrin complex: Improving solubility for application on in vitro/ in vivo Candida albicans biofilms

PubMed Central

Teodoro, Guilherme Rodrigues; Salvador, Marcos José; Koga-Ito, Cristiane Yumi

2017-01-01

The aim of this study was to increase the solubility of gallic acid (GA) for the treatment of Candida albicans biofilm, which is very difficult to treat and requires high drug concentrations. Cyclodextrins (CDs) were used for this purpose. Complexes were evaluated by phase-solubility studies, prepared by spray drying and characterized by drug loading, scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The complexes were tested on C. albicans biofilm using in vitro and in vivo models. HPβCD formed soluble inclusion complexes with GA. The percentage of GA in GA/HPβCD was 10.8 ± 0.01%. The SEM and DSC analyses confirmed the formation of inclusion complexes. GA/HPβCD maintained the antimicrobial activity of the pure GA. GA/HPβCD was effective on C. albicans biofilms of 24 and 48h. The in vivo results showed an anti-inflammatory activity of GA/HPβCD with no difference in invading hypha counting among the groups. This study encourages the development of new antifungal agents. PMID:28700692

Automated Transmission-Mode Scanning Electron Microscopy (tSEM) for Large Volume Analysis at Nanoscale Resolution

PubMed Central

Kuwajima, Masaaki; Mendenhall, John M.; Lindsey, Laurence F.; Harris, Kristen M.

2013-01-01

Transmission-mode scanning electron microscopy (tSEM) on a field emission SEM platform was developed for efficient and cost-effective imaging of circuit-scale volumes from brain at nanoscale resolution. Image area was maximized while optimizing the resolution and dynamic range necessary for discriminating key subcellular structures, such as small axonal, dendritic and glial processes, synapses, smooth endoplasmic reticulum, vesicles, microtubules, polyribosomes, and endosomes which are critical for neuronal function. Individual image fields from the tSEM system were up to 4,295 µm2 (65.54 µm per side) at 2 nm pixel size, contrasting with image fields from a modern transmission electron microscope (TEM) system, which were only 66.59 µm2 (8.160 µm per side) at the same pixel size. The tSEM produced outstanding images and had reduced distortion and drift relative to TEM. Automated stage and scan control in tSEM easily provided unattended serial section imaging and montaging. Lens and scan properties on both TEM and SEM platforms revealed no significant nonlinear distortions within a central field of ∼100 µm2 and produced near-perfect image registration across serial sections using the computational elastic alignment tool in Fiji/TrakEM2 software, and reliable geometric measurements from RECONSTRUCT™ or Fiji/TrakEM2 software. Axial resolution limits the analysis of small structures contained within a section (∼45 nm). Since this new tSEM is non-destructive, objects within a section can be explored at finer axial resolution in TEM tomography with current methods. Future development of tSEM tomography promises thinner axial resolution producing nearly isotropic voxels and should provide within-section analyses of structures without changing platforms. Brain was the test system given our interest in synaptic connectivity and plasticity; however, the new tSEM system is readily applicable to other biological systems. PMID:23555711

Toward a Model of Strategies and Summary Writing Performance

ERIC Educational Resources Information Center

Yang, Hui-Chun

2014-01-01

This study explores the construct of a summarization test task by means of single-group and multigroup structural equation modeling (SEM). It examines the interrelationships between strategy use and performance, drawing on data from 298 Taiwanese undergraduates' summary essays and their self-reported strategy use. Single-group SEM analyses…

Modeling the Relationships between Subdimensions of Environmental Literacy

ERIC Educational Resources Information Center

Genc, Murat; Akilli, Mustafa

2016-01-01

The aim of this study is to demonstrate the relationships between subdimensions of environmental literacy using Structural Equation Modeling (SEM). The study was conducted by the analysis of students' answers to questionnaires data using SEM. Initially, Kaiser-Meyer-Olkin and Bartlett's tests were done to test appropriateness of subdimensions to…

Errors of Inference in Structural Equation Modeling

ERIC Educational Resources Information Center

McCoach, D. Betsy; Black, Anne C.; O'Connell, Ann A.

2007-01-01

Although structural equation modeling (SEM) is one of the most comprehensive and flexible approaches to data analysis currently available, it is nonetheless prone to researcher misuse and misconceptions. This article offers a brief overview of the unique capabilities of SEM and discusses common sources of user error in drawing conclusions from…

A Methodological Review of Structural Equation Modelling in Higher Education Research

ERIC Educational Resources Information Center

Green, Teegan

2016-01-01

Despite increases in the number of articles published in higher education journals using structural equation modelling (SEM), research addressing their statistical sufficiency, methodological appropriateness and quantitative rigour is sparse. In response, this article provides a census of all covariance-based SEM articles published up until 2013…

AxiSEM3D: broadband seismic wavefields in 3-D aspherical Earth models

NASA Astrophysics Data System (ADS)

Leng, K.; Nissen-Meyer, T.; Zad, K. H.; van Driel, M.; Al-Attar, D.

2017-12-01

Seismology is the primary tool for data-informed inference of Earth structure and dynamics. Simulating seismic wave propagation at a global scale is fundamental to seismology, but remains as one of most challenging problems in scientific computing, because of both the multiscale nature of Earth's interior and the observable frequency band of seismic data. We present a novel numerical method to simulate global seismic wave propagation in realistic 3-D Earth models. Our method, named AxiSEM3D, is a hybrid of spectral element method and pseudospectral method. It reduces the azimuthal dimension of wavefields by means of a global Fourier series parameterization, of which the number of terms can be locally adapted to the inherent azimuthal smoothness of the wavefields. AxiSEM3D allows not only for material heterogeneities, such as velocity, density, anisotropy and attenuation, but also for finite undulations on radial discontinuities, both solid-solid and solid-fluid, and thereby a variety of aspherical Earth features such as ellipticity, topography, variable crustal thickness, and core-mantle boundary topography. Such interface undulations are equivalently interpreted as material perturbations of the contiguous media, based on the "particle relabelling transformation". Efficiency comparisons show that AxiSEM3D can be 1 to 3 orders of magnitude faster than conventional 3-D methods, with the speedup increasing with simulation frequency and decreasing with model complexity, but for all realistic structures the speedup remains at least one order of magnitude. The observable frequency range of global seismic data (up to 1 Hz) has been covered for wavefield modelling upon a 3-D Earth model with reasonable computing resources. We show an application of surface wave modelling within a state-of-the-art global crustal model (Crust1.0), with the synthetics compared to real data. The high-performance C++ code is released at github.com/AxiSEM3D/AxiSEM3D.

Expanding the Conversation about SEM: Advancing SEM Efforts to Improve Student Learning and Persistence--Part II

ERIC Educational Resources Information Center

Yale, Amanda

2010-01-01

The first article in this two-part series focused on the need for enrollment management conceptual and organizational models to focus more intentionally and purposefully on efforts related to improving student learning, success, and persistence. Time and again, SEM is viewed from a conventional lens comprising marketing, recruitment and …

Fabricating the spherical and flake silver powder used for the optoelectronic devices

NASA Astrophysics Data System (ADS)

Ju, Wei; Ma, Wangjing; Zhang, Fangzhi; Chen, Yixiang; Xie, Jinpeng

2018-01-01

The spherical and flake silver powder with different particle size for the optoelectronic devices was partly prepared by using chemical reduction and ball milling method, and charactered by scanning electron microscope (SEM), X-ray diffraction (XRD), laser particle size analyzer and thermo-gravimetric(TG) analyzer. The particle size of three series of spherical silver powder fabricated by chemical reduction is about 1.5μm, 1μm and 0.6μm, respectively; after being mechanical milling, the particle size of flake silver powder with high flaky rate is about 10μm, 6μm and 2μm respectively. Thermo gravimetric (TG) and XRD analyses showed that the silver powders have high purity and crystalline, and then the laser particle size and SEM analyses showed that the silver powders has good uniformity.

Minimal resin embedding of multicellular specimens for targeted FIB-SEM imaging.

PubMed

Schieber, Nicole L; Machado, Pedro; Markert, Sebastian M; Stigloher, Christian; Schwab, Yannick; Steyer, Anna M

2017-01-01

Correlative light and electron microscopy (CLEM) is a powerful tool to perform ultrastructural analysis of targeted tissues or cells. The large field of view of the light microscope (LM) enables quick and efficient surveys of the whole specimen. It is also compatible with live imaging, giving access to functional assays. CLEM protocols take advantage of the features to efficiently retrace the position of targeted sites when switching from one modality to the other. They more often rely on anatomical cues that are visible both by light and electron microscopy. We present here a simple workflow where multicellular specimens are embedded in minimal amounts of resin, exposing their surface topology that can be imaged by scanning electron microscopy (SEM). LM and SEM both benefit from a large field of view that can cover whole model organisms. As a result, targeting specific anatomic locations by focused ion beam-SEM (FIB-SEM) tomography becomes straightforward. We illustrate this application on three different model organisms, used in our laboratory: the zebrafish embryo Danio rerio, the marine worm Platynereis dumerilii, and the dauer larva of the nematode Caenorhabditis elegans. Here we focus on the experimental steps to reduce the amount of resin covering the samples and to image the specimens inside an FIB-SEM. We expect this approach to have widespread applications for volume electron microscopy on multiple model organisms. Copyright © 2017 Elsevier Inc. All rights reserved.

Plastic vs. Self-Expandable Metal Stents for Palliation in Malignant Biliary Obstruction: A Series of Meta-Analyses.

PubMed

Almadi, Majid A; Barkun, Alan; Martel, Myriam

2017-02-01

Self-expandable metal stents (SEMS) are thought to have an advantage over plastic stents in achieving biliary drainage. We performed a systematic search of MEDLINE, EMBASE, Scopus, CENTRAL, and ISI Web of knowledge databases, from January 1980 to September 2015, for randomized-controlled trials (RCTs) comparing SEMS vs. plastic stents in the palliation of malignant biliary obstruction. Primary outcomes were durations of stent patency, patient survival, and 30-day mortality. Numerous secondary outcomes were assessed, and extensive sensitivity and subgroup analyses were performed. In all, 20 RCTs totaling 1,713 patients yielded a weighted mean difference (WMD) in time to stent patency (4 studies) of 4.45 months (95% confidence interval (CI), 0.31, 8.59; GRADE=moderate) favoring SEMS. There were no differences in overall patient survival (5 studies) WMD=0.67 months (95% CI, -0.66, 1.99; GRADE=moderate), or 30-day mortality (8 studies) odds ratio (OR)=0.80 (95% CI, 0.52, 1.24; GRADE=moderate) but there was a higher symptom-free survival at 6 months (4 studies) OR=5.96 (95% CI, 1.71, 20.81; GRADE=moderate). SEMS use resulted in lower rates of late complications (11 studies) OR=0.43 (95% CI, 0.26, 0.71; GRADE=moderate), sepsis or cholangitis (14 studies) OR=0.53 (95% CI, 0.37, 0.77; GRADE=high), blocking from sludge (8 studies) OR=0.11(95% CI, 0.07, 0.17; GRADE=moderate), and mean number of re-interventions (8 studies) WMD=-0.83 interventions (95% CI, -1.64, -0.02; GRADE=moderate). There was a longer patency of SEMS for those without a prior drainage attempt (2 studies) WMD 7.70 months (95% CI, 7.14, 8.25; GRADE=high). Although a survival advantage was found when an uncovered SEMS was used (3 studies) WMD 1.31 months (95% CI, 0.30, 2.32; GRADE=high), but not partially or fully covered SEMS (2 studies) WMD -0.66 months (95% CI, -1.02, -0.30; GRADE=high) vs. plastic stents, and for SEMS in the setting of pre- or post-procedural antibiotic administration (2 studies) WMD 1.49 months (95% CI, 0.27, 2.70; GRADE=high), and performance of a sphincterotomy (2 studies) WMD 1.63 months (95% CI, 0.42, 2.84; GRADE=high). Keeping in mind the noted risk of bias in source data, the use of SEMS compared with plastic stents, in the palliation of patients with malignant biliary obstruction results in longer stent patency, lower complications rates, and fewer re-interventions, whereas exhibiting survival benefits in selected subgroups of patients.

Genome-wide association study of offspring birth weight in 86 577 women identifies five novel loci and highlights maternal genetic effects that are independent of fetal genetics.

PubMed

Beaumont, Robin N; Warrington, Nicole M; Cavadino, Alana; Tyrrell, Jessica; Nodzenski, Michael; Horikoshi, Momoko; Geller, Frank; Myhre, Ronny; Richmond, Rebecca C; Paternoster, Lavinia; Bradfield, Jonathan P; Kreiner-Møller, Eskil; Huikari, Ville; Metrustry, Sarah; Lunetta, Kathryn L; Painter, Jodie N; Hottenga, Jouke-Jan; Allard, Catherine; Barton, Sheila J; Espinosa, Ana; Marsh, Julie A; Potter, Catherine; Zhang, Ge; Ang, Wei; Berry, Diane J; Bouchard, Luigi; Das, Shikta; Hakonarson, Hakon; Heikkinen, Jani; Helgeland, Øyvind; Hocher, Berthold; Hofman, Albert; Inskip, Hazel M; Jones, Samuel E; Kogevinas, Manolis; Lind, Penelope A; Marullo, Letizia; Medland, Sarah E; Murray, Anna; Murray, Jeffrey C; Njølstad, Pål R; Nohr, Ellen A; Reichetzeder, Christoph; Ring, Susan M; Ruth, Katherine S; Santa-Marina, Loreto; Scholtens, Denise M; Sebert, Sylvain; Sengpiel, Verena; Tuke, Marcus A; Vaudel, Marc; Weedon, Michael N; Willemsen, Gonneke; Wood, Andrew R; Yaghootkar, Hanieh; Muglia, Louis J; Bartels, Meike; Relton, Caroline L; Pennell, Craig E; Chatzi, Leda; Estivill, Xavier; Holloway, John W; Boomsma, Dorret I; Montgomery, Grant W; Murabito, Joanne M; Spector, Tim D; Power, Christine; Järvelin, Marjo-Ritta; Bisgaard, Hans; Grant, Struan F A; Sørensen, Thorkild I A; Jaddoe, Vincent W; Jacobsson, Bo; Melbye, Mads; McCarthy, Mark I; Hattersley, Andrew T; Hayes, M Geoffrey; Frayling, Timothy M; Hivert, Marie-France; Felix, Janine F; Hyppönen, Elina; Lowe, William L; Evans, David M; Lawlor, Debbie A; Feenstra, Bjarke; Freathy, Rachel M

2018-02-15

Genome-wide association studies of birth weight have focused on fetal genetics, whereas relatively little is known about the role of maternal genetic variation. We aimed to identify maternal genetic variants associated with birth weight that could highlight potentially relevant maternal determinants of fetal growth. We meta-analysed data on up to 8.7 million SNPs in up to 86 577 women of European descent from the Early Growth Genetics (EGG) Consortium and the UK Biobank. We used structural equation modelling (SEM) and analyses of mother-child pairs to quantify the separate maternal and fetal genetic effects. Maternal SNPs at 10 loci (MTNR1B, HMGA2, SH2B3, KCNAB1, L3MBTL3, GCK, EBF1, TCF7L2, ACTL9, CYP3A7) were associated with offspring birth weight at P < 5 × 10-8. In SEM analyses, at least 7 of the 10 associations were consistent with effects of the maternal genotype acting via the intrauterine environment, rather than via effects of shared alleles with the fetus. Variants, or correlated proxies, at many of the loci had been previously associated with adult traits, including fasting glucose (MTNR1B, GCK and TCF7L2) and sex hormone levels (CYP3A7), and one (EBF1) with gestational duration. The identified associations indicate that genetic effects on maternal glucose, cytochrome P450 activity and gestational duration, and potentially on maternal blood pressure and immune function, are relevant for fetal growth. Further characterization of these associations in mechanistic and causal analyses will enhance understanding of the potentially modifiable maternal determinants of fetal growth, with the goal of reducing the morbidity and mortality associated with low and high birth weights. © The Author(s) 2018. Published by Oxford University Press.

Genome-wide association study of offspring birth weight in 86 577 women identifies five novel loci and highlights maternal genetic effects that are independent of fetal genetics

PubMed Central

Beaumont, Robin N; Warrington, Nicole M; Cavadino, Alana; Tyrrell, Jessica; Nodzenski, Michael; Horikoshi, Momoko; Geller, Frank; Myhre, Ronny; Richmond, Rebecca C; Paternoster, Lavinia; Bradfield, Jonathan P; Kreiner-Møller, Eskil; Huikari, Ville; Metrustry, Sarah; Lunetta, Kathryn L; Painter, Jodie N; Hottenga, Jouke-Jan; Allard, Catherine; Barton, Sheila J; Espinosa, Ana; Marsh, Julie A; Potter, Catherine; Zhang, Ge; Ang, Wei; Berry, Diane J; Bouchard, Luigi; Das, Shikta; Hakonarson, Hakon; Heikkinen, Jani; Helgeland, Øyvind; Hocher, Berthold; Hofman, Albert; Inskip, Hazel M; Jones, Samuel E; Kogevinas, Manolis; Lind, Penelope A; Marullo, Letizia; Medland, Sarah E; Murray, Anna; Murray, Jeffrey C; Njølstad, Pål R; Nohr, Ellen A; Reichetzeder, Christoph; Ring, Susan M; Ruth, Katherine S; Santa-Marina, Loreto; Scholtens, Denise M; Sebert, Sylvain; Sengpiel, Verena; Tuke, Marcus A; Vaudel, Marc; Weedon, Michael N; Willemsen, Gonneke; Wood, Andrew R; Yaghootkar, Hanieh; Muglia, Louis J; Bartels, Meike; Relton, Caroline L; Pennell, Craig E; Chatzi, Leda; Estivill, Xavier; Holloway, John W; Boomsma, Dorret I; Montgomery, Grant W; Murabito, Joanne M; Spector, Tim D; Power, Christine; Järvelin, Marjo-Ritta; Bisgaard, Hans; Grant, Struan F A; Sørensen, Thorkild I A; Jaddoe, Vincent W; Jacobsson, Bo; Melbye, Mads; McCarthy, Mark I; Hattersley, Andrew T; Hayes, M Geoffrey; Frayling, Timothy M; Hivert, Marie-France; Felix, Janine F; Hyppönen, Elina; Lowe, William L; Evans, David M; Lawlor, Debbie A; Feenstra, Bjarke

2018-01-01

Abstract Genome-wide association studies of birth weight have focused on fetal genetics, whereas relatively little is known about the role of maternal genetic variation. We aimed to identify maternal genetic variants associated with birth weight that could highlight potentially relevant maternal determinants of fetal growth. We meta-analysed data on up to 8.7 million SNPs in up to 86 577 women of European descent from the Early Growth Genetics (EGG) Consortium and the UK Biobank. We used structural equation modelling (SEM) and analyses of mother–child pairs to quantify the separate maternal and fetal genetic effects. Maternal SNPs at 10 loci (MTNR1B, HMGA2, SH2B3, KCNAB1, L3MBTL3, GCK, EBF1, TCF7L2, ACTL9, CYP3A7) were associated with offspring birth weight at P < 5 × 10−8. In SEM analyses, at least 7 of the 10 associations were consistent with effects of the maternal genotype acting via the intrauterine environment, rather than via effects of shared alleles with the fetus. Variants, or correlated proxies, at many of the loci had been previously associated with adult traits, including fasting glucose (MTNR1B, GCK and TCF7L2) and sex hormone levels (CYP3A7), and one (EBF1) with gestational duration. The identified associations indicate that genetic effects on maternal glucose, cytochrome P450 activity and gestational duration, and potentially on maternal blood pressure and immune function, are relevant for fetal growth. Further characterization of these associations in mechanistic and causal analyses will enhance understanding of the potentially modifiable maternal determinants of fetal growth, with the goal of reducing the morbidity and mortality associated with low and high birth weights. PMID:29309628

Intraoral laser welding: ultrastructural and mechanical analysis to compare laboratory laser and dental laser.

PubMed

Fornaini, Carlo; Passaretti, Francesca; Villa, Elena; Rocca, Jean-Paul; Merigo, Elisabetta; Vescovi, Paolo; Meleti, Marco; Manfredi, Maddalena; Nammour, Samir

2011-07-01

The Nd:YAG laser has been used since 1970 in dental laboratories to weld metals on dental prostheses. Recently in several clinical cases, we have suggested that the Nd:YAG laser device commonly utilized in the dental office could be used to repair broken fixed, removable and orthodontic prostheses and to weld metals directly in the mouth. The aim of this work was to evaluate, using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and dynamic mechanical analysis (DMA), the quality of the weld and its mechanical strength, comparing a device normally used in dental laboratory and a device normally used in the dental office for oral surgery, the same as that described for intraoral welding. Metal plates of a Co-Cr-Mo dental alloy and steel orthodontic wires were subjected to four welding procedures: welding without filler metal using the laboratory laser, welding with filler metal using the laboratory laser, welding without filler metal using the office laser, and welding with filler metal using the office laser. The welded materials were then analysed by SEM, EDS and DMA. SEM analysis did not show significant differences between the samples although the plates welded using the office laser without filler metal showed a greater number of fissures than the other samples. EDS microanalysis of the welding zone showed a homogeneous composition of the metals. Mechanical tests showed similar elastic behaviours of the samples, with minimal differences between the samples welded with the two devices. No wire broke even under the maximum force applied by the analyser. This study seems to demonstrate that the welds produced using the office Nd:YAG laser device and the laboratory Nd:YAG laser device, as analysed by SEM, EDS and DMA, showed minimal and nonsignificant differences, although these findings need to be confirmed using a greater number of samples.

Intraoral Laser Welding (ILW): ultrastructural and mechanical analysis

NASA Astrophysics Data System (ADS)

Fornaini, Carlo; Passaretti, Francesca; Villa, Elena; Nammour, Samir

2010-05-01

Nd:YAG, currently used since 1970 in dental laboratories to weld metals on dental prostheses has some limits such great dimensions, high costs and fixed delivery system. Recently it was proposed the possibility to use the Nd:YAG laser device commonly utilised in dental office, to repair broken fixed, removable and orthodontic prostheses and to weld metals directly into the mouth. The aim of this work is to value, through SEM (Scanning Electron Microscope), EDS (Energy Dispersive X-Ray Spectroscopy) and DMA (Dynamic Mechanical Analysis), quality and mechanical strength of the welding process comparing a device normally used in dental lab and a device normally used in dental office for oral surgery. Sixteen CoCrMo metal plates and twenty steel orthodontic wires were divided in four groups: one was welded without metal apposition by laboratory laser, one was welded with metal apposition by laboratory laser, one was welded without metal apposition by office laser and one was welded with metal apposition by office laser. The welding process was analysed by SEM, EDS and DMA to compare the differences between the different samples. By SEM analysis it was seen that the plates welded by office laser without apposition metal showed a greater number of fissurations compared with the other samples. By EDS analysis it was seen a homogeneous composition of the metals in all the samples. The mechanical tests showed a similar elastic behaviour of the samples, with minimal differences between the two devices. No wire broke even under the maximum strength by the Analyser. This study seems to demonstrate that the welding process by office Nd:YAG laser device and the welding process by laboratory Nd:YAG laser device, analysed by SEM, EDS and DMA, showed minimal and not significant differences even if these data will be confirmed by a greater number of samples.

Mathematical model of the seismic electromagnetic signals (SEMS) in non crystalline substances

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dennis, L. C. C.; Yahya, N.; Daud, H.

The mathematical model of seismic electromagnetic waves in non crystalline substances is developed and the solutions are discussed to show the possibility of improving the electromagnetic waves especially the electric field. The shear stress of the medium in fourth order tensor gives the equation of motion. Analytic methods are selected for the solutions written in Hansen vector form. From the simulated SEMS, the frequency of seismic waves has significant effects to the SEMS propagating characteristics. EM waves transform into SEMS or energized seismic waves. Traveling distance increases once the frequency of the seismic waves increases from 100% to 1000%. SEMSmore » with greater seismic frequency will give seismic alike waves but greater energy is embedded by EM waves and hence further distance the waves travel.« less

SEM/EDS and optical microscopy analyses of microplastics in ocean trawl and fish guts.

PubMed

Wang, Zhong-Min; Wagner, Jeff; Ghosal, Sutapa; Bedi, Gagandeep; Wall, Stephen

2017-12-15

Microplastic particles from Atlantic and Pacific Ocean trawls, lab-fed fish guts and ocean fish guts have been characterized using optical microscopy and SEM/EDS in terms of size, morphology, and chemistry. We assessed whether these measurements could serve as a rapid screening process for subsequent identification of the likely microplastic candidates by micro-spectroscopy. Optical microscopy enabled morphological classification of the types of particles or fibers present in the sample, as well as the quantification of particle size ranges and fiber lengths. SEM/EDS analysis was used to rule out non-plastic particles and screen the prepared samples for potential microplastic, based on their element signatures and surface characteristics. Chlorinated plastics such as polyvinyl chloride (PVC) could be easily identified with SEM/EDS due to their unique elemental signatures including chlorine, as could mineral species that are falsely identified as plastics by optical microscopy. Particle morphology determined by optical microscopy and SEM suggests the fish ingested particles contained both degradation fragments from larger plastic pieces and also manufactured microplastics. SEM images of microplastic particle surfaces revealed characteristic cracks consistent with environmental exposure, as well as pigment particles consistent with manufactured materials. Most of the microplastic surfaces in the fish guts and ocean trawls were covered with biofilms, radiolarians, and crustaceans. Many of the fish stomachs contained micro-shell pieces which visually resembled microplastics. Copyright © 2017 Elsevier B.V. All rights reserved.

Subjective Values of Quality of Life Dimensions in Elderly People. A SEM Preference Model Approach

ERIC Educational Resources Information Center

Elosua, Paula

2011-01-01

This article proposes a Thurstonian model in the framework of Structural Equation Modelling (SEM) to assess preferences among quality of life dimensions for the elderly. Data were gathered by a paired comparison design in a sample comprised of 323 people aged from 65 to 94 years old. Five dimensions of quality of life were evaluated: Health,…

Child-mother and child-father attachment security: links to internalizing adjustment among children with learning disabilities.

PubMed

Al-Yagon, Michal

2014-02-01

The study examined the unique role of children's attachment with the father and with the mother, in explaining differences in internalizing features (i.e., loneliness, sense of coherence, hope and effort, and internalizing behavior syndrome) among 107 children with learning disabilities (LD) versus 98 children with typical development ages 8-12. Preliminary analyses yielded significant group differences on most measures. SEM analysis indicated high fit between the theoretical model and empirical findings, and different patterns of relations among the model's components for the two populations. As hypothesized, child-father and child-mother attachment contributed differently to children's internalizing features for the two subgroups. Discussion focused on understanding unique and complementary roles of attachment relations with fathers versus mothers among children with and without LD.

Thermocatalytic Behavior of Manganese (IV) Oxide as Nanoporous Material on the Dissociation of a Gas Mixture Containing Hydrogen Peroxide.

PubMed

Jildeh, Zaid B; Oberländer, Jan; Kirchner, Patrick; Wagner, Patrick H; Schöning, Michael J

2018-04-21

In this article, we present an overview on the thermocatalytic reaction of hydrogen peroxide (H 2 O 2 ) gas on a manganese (IV) oxide (MnO 2 ) catalytic structure. The principle of operation and manufacturing techniques are introduced for a calorimetric H 2 O 2 gas sensor based on porous MnO 2 . Results from surface analyses by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) of the catalytic material provide indication of the H 2 O 2 dissociation reaction schemes. The correlation between theory and the experiments is documented in numerical models of the catalytic reaction. The aim of the numerical models is to provide further information on the reaction kinetics and performance enhancement of the porous MnO 2 catalyst.

A Review of Structural Equation Modeling Applications in Turkish Educational Science Literature, 2010-2015

ERIC Educational Resources Information Center

Karakaya-Ozyer, Kubra; Aksu-Dunya, Beyza

2018-01-01

Structural equation modeling (SEM) is one of the most popular multivariate statistical techniques in Turkish educational research. This study elaborates the SEM procedures employed by 75 educational research articles which were published from 2010 to 2015 in Turkey. After documenting and coding 75 academic papers, categorical frequencies and…

Teacher's Corner: Structural Equation Modeling with the Sem Package in R

ERIC Educational Resources Information Center

Fox, John

2006-01-01

R is free, open-source, cooperatively developed software that implements the S statistical programming language and computing environment. The current capabilities of R are extensive, and it is in wide use, especially among statisticians. The sem package provides basic structural equation modeling facilities in R, including the ability to fit…

Meta-Analytic Structural Equation Modeling: A Two-Stage Approach

ERIC Educational Resources Information Center

Cheung, Mike W. L.; Chan, Wai

2005-01-01

To synthesize studies that use structural equation modeling (SEM), researchers usually use Pearson correlations (univariate r), Fisher z scores (univariate z), or generalized least squares (GLS) to combine the correlation matrices. The pooled correlation matrix is then analyzed by the use of SEM. Questionable inferences may occur for these ad hoc…

Comparison of non-Gaussian and Gaussian diffusion models of diffusion weighted imaging of rectal cancer at 3.0 T MRI.

PubMed

Zhang, Guangwen; Wang, Shuangshuang; Wen, Didi; Zhang, Jing; Wei, Xiaocheng; Ma, Wanling; Zhao, Weiwei; Wang, Mian; Wu, Guosheng; Zhang, Jinsong

2016-12-09

Water molecular diffusion in vivo tissue is much more complicated. We aimed to compare non-Gaussian diffusion models of diffusion-weighted imaging (DWI) including intra-voxel incoherent motion (IVIM), stretched-exponential model (SEM) and Gaussian diffusion model at 3.0 T MRI in patients with rectal cancer, and to determine the optimal model for investigating the water diffusion properties and characterization of rectal carcinoma. Fifty-nine consecutive patients with pathologically confirmed rectal adenocarcinoma underwent DWI with 16 b-values at a 3.0 T MRI system. DWI signals were fitted to the mono-exponential and non-Gaussian diffusion models (IVIM-mono, IVIM-bi and SEM) on primary tumor and adjacent normal rectal tissue. Parameters of standard apparent diffusion coefficient (ADC), slow- and fast-ADC, fraction of fast ADC (f), α value and distributed diffusion coefficient (DDC) were generated and compared between the tumor and normal tissues. The SEM exhibited the best fitting results of actual DWI signal in rectal cancer and the normal rectal wall (R 2  = 0.998, 0.999 respectively). The DDC achieved relatively high area under the curve (AUC = 0.980) in differentiating tumor from normal rectal wall. Non-Gaussian diffusion models could assess tissue properties more accurately than the ADC derived Gaussian diffusion model. SEM may be used as a potential optimal model for characterization of rectal cancer.

Associations Between Croatian Adolescents' Use of Sexually Explicit Material and Sexual Behavior: Does Parental Monitoring Play a Role?

PubMed

Tomić, Ivan; Burić, Jakov; Štulhofer, Aleksandar

2017-10-25

The use of sexually explicit material (SEM) has become a part of adolescent sexual socialization, at least in the Western world. Adolescent and young people's SEM use has been associated with risky sexual behaviors, which has recently resulted in policy debates about restricting access to SEM. Such development seems to suggest a crisis of the preventive role of parental oversight. Based on the Differential Susceptibility to Media Effects Model, this study assessed the role of parental monitoring in the context of adolescent vulnerability to SEM-associated risky or potentially adverse outcomes (sexual activity, sexual aggressiveness, and sexting). Using an online sample of Croatian 16-year-olds (N = 1265) and structural equation modeling approach, parental monitoring was found consistently and negatively related to the problematic behavioral outcomes, regardless of participants' gender. While SEM use was related to sexual experience and sexting, higher levels of parental monitoring were associated with less frequent SEM use and lower acceptance of sexual permissiveness. Despite parents' fears about losing the ability to monitor their adolescent children's lives in the Internet era, there is evidence that parental engagement remains an important protective factor.

Biofilm removal by 6% sodium hypochlorite activated by different irrigation techniques.

PubMed

Ordinola-Zapata, R; Bramante, C M; Aprecio, R M; Handysides, R; Jaramillo, D E

2014-07-01

To compare the removal of biofilm utilizing four irrigation techniques on a bovine root canal model. Fifty dentine specimens (2 × 2 mm) were infected with biofilm. The samples were then adapted to previously created cavities in the bovine model. The root canals were irrigated twice with 2 mL of 6% sodium hypochlorite for 2 min (4 min total). Following initial irrigation, the different treatment modalities were introduced for 60 s (3 × 20 s intervals). The evaluated techniques were needle irrigation, Endoactivator (Dentsply Tulsa Dental, Tulsa, OK, USA), passive ultrasonic irrigation and laser-activated irrigation (photon-induced photoacoustic streaming). The controls were irrigated with distilled water and conventional needle irrigation. Subsequently, the dentine samples were separated from the model and analysed using a scanning electron microscope (SEM). Fifteen operative fields were scanned per block, and SEM pictures were captured. Two calibrated evaluators examined the images and collected data using a four-degree scale. Nonparametric tests were used to evaluate for statistical significance amongst the groups. The group undergoing laser-activated irrigation using photon-induced photoacoustic streaming exhibited the most favourable results in the removal of biofilm. Passive ultrasonic irrigation scores were significantly lower than both the Endoactivator and needle irrigation scores. Sonic and needle irrigation were not significantly different. The least favourable results were found in the control group. Laser activation of 6% sodium hypochlorite significantly improved the cleaning of biofilm-infected dentine followed by passive ultrasonic irrigation. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Grape stalks biomass as raw material for activated carbon production: synthesis, characterization and adsorption ability

NASA Astrophysics Data System (ADS)

Hashemi Shahraki, Zahra; Sharififard, Hakimeh; Lashanizadegan, Asghar

2018-05-01

In order to produce activated carbon from grape stalks, this biomass was activated chemically with KOH. Identification methods including FTIR, BET, SEM, Boehm titration and pHzpc measurement were applied to characterize the produced carbon. The adsorption ability of produced activated carbon toward cadmium removal from aqueous solution was evaluated by using Central Composite Design methodology and the effects of process parameters were analysed, as well as, the optimum processing conditions were determined using statistical methods. In order to characterize the equilibrium behaviour of adsorption process, the equilibrium data were analysed by Langmuir, Freundlich, and R-D isotherm models. Results indicated that the adsorption process is a monolayer process and the adsorption capacity of prepared activated carbon was 140.84 mg L‑1. Analysis of kinetics data showed that the pseudo-second-order and Elovich models were well fitted with the kinetics results and this suggests the domination of chemical adsorption. The regenerability results showed that the prepared activated carbon has a reasonable adsorption capacity toward cadmium after five adsorption/desorption cycles.

Microstructure of Concrete with Aggregates from Construction and Demolition Waste Recycling Plants.

PubMed

Bravo, Miguel; Santos Silva, António; de Brito, Jorge; Evangelista, Luís

2016-02-01

This paper intends to analyze the microstructure of concrete with recycled aggregates (RA) from construction and demolition waste from various Portuguese recycling plants. To that effect, several scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses were performed. Various concrete mixes were evaluated in order to analyze the influence of the RA's collection point and consequently of their composition on the mixes' characteristics. Afterward all the mixes were subjected to the capillary water absorption test in order to quantitatively evaluate their porosity. Results from the SEM/EDS analysis were compared with those from capillary water absorption test. The SEM/EDS analysis showed that the bond capacity of aggregates to the new cement paste is greatly influenced by the RA's nature. On the other hand, there was an increase in porosity with the incorporation of RA.

Nutrition, Balance and Fear of Falling as Predictors of Risk for Falls among Filipino Elderly in Nursing Homes: A Structural Equation Model (SEM)

ERIC Educational Resources Information Center

de Guzman, Allan B.; Ines, Joanna Louise C.; Inofinada, Nina Josefa A.; Ituralde, Nielson Louie J.; Janolo, John Robert E.; Jerezo, Jnyv L.; Jhun, Hyae Suk J.

2013-01-01

While a number of empirical studies have been conducted regarding risk for falls among the elderly, there is still a paucity of similar studies in a developing country like the Philippines. This study purports to test through Structural Equation Modeling (SEM) a model that shows the interaction between and among nutrition, balance, fear of…

Femtosecond laser ablation of cemented carbides: properties and tribological applications

NASA Astrophysics Data System (ADS)

Dumitru, G.; Romano, V.; Weber, H. P.; Gerbig, Y.; Haefke, H.; Bruneau, S.; Hermann, J.; Sentis, M.

Laser ablation with fs laser pulses was performed in air on cobalt cemented tungsten carbide by means of a Ti : sapphire laser (800 nm, 100 fs). Small and moderate fluences (2, 5, 10 J/cm2) and up to 5×104 pulses per irradiated spot were used to drill holes with aspect ratios up to 10. Cross-section cuts from laser-irradiated samples were produced and they were analysed with optical microscopy and SEM. EDX analyses were carried out on selected zones. Quasi-cylindrical holes were found for 2 J/cm2, whereas for 5 and 10 J/cm2 irregular shapes (lobes, bottoms wider than hole entrances) were found to occur after a given number of incident pulses. Layers with modified structure were evidenced at pore walls. SEM revealed a denser structure, while EDX analyses showed uniform and almost similar contents of W, C, and Co in these layers. As a direct application, patterning of coated WC-Co was carried out with 2 J/cm2 and 100 pulses per pore. The resulted surfaces were tribologically tested and these tests revealed an improved friction and wear behaviour.

Black Stains: a microbiological analysis and a view on familiarity and susceptibility to tooth decay of patients in childhood.

PubMed

Tripodi, D; Martinelli, D; Pasini, M; Giuca, M R; D'Ercole, S

2016-12-01

Assess prevalence, familial predisposition and susceptibility to caries of Black Stains (BS). Evaluate the microbiological composition of BS, saliva and subgingival plaque. Sixty nine subjects with BS (test group) and 120 subjects without BS (control group) were analysed for oral status. For each BS-patient, a BS-deposit, 1 ml of saliva and subgingival plaque were collected and microbiologically analysed. Five deciduous teeth with BS were observed under SEM. This study showed a BS prevalence similar to that of the Mediterranean area and a familiality. The microbiological origin of BS was confirmed by SEM and culture method and the BS flora differ from that of supragingival plaque. Predominance in BS and saliva of Actinomycetes and the low salivary prevalence of S. mutans and L. acidophilus may be related with low caries incidence in BS patients. The high presence of Actinomyces spp can be a causative factor for BS.

Characterization of minerals in air dust particles in the state of Tamilnadu, India through FTIR, XRD and SEM analyses

NASA Astrophysics Data System (ADS)

Senthil Kumar, R.; Rajkumar, P.

2014-11-01

The abstract of this paper explains the presence of minerals in air which causes great concern regarding public health issues. The spectroscopic investigation of air dust particles of several samples in various locations in the state of Tamilnadu, India is reported. Qualitative analyses were carried out to determine the major and minor constituent minerals present in the samples based on the FTIR, XRD absorption peaks. This study also identified the minerals like quartz, asbestos, kaolinite, calcite, hematite, montmorillonite, nacrite and several other trace minerals in the air dust particles. The presents of quartz is mainly found in all the samples invariably. Hence the percentage of quartz and its crystalline nature were determined with the help of extinction co-efficient and crystallinity index respectively. The shape and size of the particulates are studied with SEM analysis.

Characterization of individual complex particles in urban atmospheric environment

NASA Astrophysics Data System (ADS)

Suzuki, K.; Takii, T.; Tomiyasu, B.; Nihei, Y.

2006-07-01

The origins of carrier particles of complex particles (iron-rich particles) collected from the urban atmospheric environment near to road traffic and a railroad were investigated from the detailed surface information using FE-SEM/EDS and TOF-SIMS analyses. From the FE-SEM/EDS analyses, the iron-rich particles were classified into two typical types (spherical type and non-spherical type). From the TOF-SIMS measurements, the characteristic secondary ions of spherical type of iron-rich particles were 23Na + and 39K +. The minor components of non-spherical type were Al, Ca and Ba. On the other hand, we carried out TOF-SIMS measurement to materials of rail origin and brake origin. From the comparison of these spectra pattern, it seemed that the spherical type of iron-rich particles was emitted from the rail origin. We concluded that the origin of non-spherical type of iron-rich particles were brake pad of vehicles.

Chapter 14: Electron Microscopy on Thin Films for Solar Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Romero, Manuel; Abou-Ras, Daniel; Nichterwitz, Melanie

2016-07-22

This chapter overviews the various techniques applied in scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and highlights their possibilities and also limitations. It gives the various imaging and analysis techniques applied on a scanning electron microscope. The chapter shows that imaging is divided into that making use of secondary electrons (SEs) and of backscattered electrons (BSEs), resulting in different contrasts in the images and thus providing information on compositions, microstructures, and surface potentials. Whenever aiming for imaging and analyses at scales of down to the angstroms range, TEM and its related techniques are appropriate tools. In many cases,more » also SEM techniques provide the access to various material properties of the individual layers, not requiring specimen preparation as time consuming as TEM techniques. Finally, the chapter dedicates to cross-sectional specimen preparation for electron microscopy. The preparation decides indeed on the quality of imaging and analyses.« less

Examination of Self-Determination within the Sport Education Model

ERIC Educational Resources Information Center

Perlman, Dana J.

2011-01-01

The purpose of this study was to examine the influence of the Sport Education Model (SEM) on students' self-determined motivation and underlying psychological need(s) in physical education. A total of 182 Year-9 students were engaged in 20 lesson units of volleyball, using either the SEM or a traditional approach. Data was collected using a…

Meta-Analytic Methods of Pooling Correlation Matrices for Structural Equation Modeling under Different Patterns of Missing Data

ERIC Educational Resources Information Center

Furlow, Carolyn F.; Beretvas, S. Natasha

2005-01-01

Three methods of synthesizing correlations for meta-analytic structural equation modeling (SEM) under different degrees and mechanisms of missingness were compared for the estimation of correlation and SEM parameters and goodness-of-fit indices by using Monte Carlo simulation techniques. A revised generalized least squares (GLS) method for…

A SEM Model in Assessing the Effect of Convergent, Divergent and Logical Thinking on Students' Understanding of Chemical Phenomena

ERIC Educational Resources Information Center

Stamovlasis, D.; Kypraios, N.; Papageorgiou, G.

2015-01-01

In this study, structural equation modeling (SEM) is applied to an instrument assessing students' understanding of chemical change. The instrument comprised items on understanding the structure of substances, chemical changes and their interpretation. The structural relationships among particular groups of items are investigated and analyzed using…

Quantified choice of root-mean-square errors of approximation for evaluation and power analysis of small differences between structural equation models.

PubMed

Li, Libo; Bentler, Peter M

2011-06-01

MacCallum, Browne, and Cai (2006) proposed a new framework for evaluation and power analysis of small differences between nested structural equation models (SEMs). In their framework, the null and alternative hypotheses for testing a small difference in fit and its related power analyses were defined by some chosen root-mean-square error of approximation (RMSEA) pairs. In this article, we develop a new method that quantifies those chosen RMSEA pairs and allows a quantitative comparison of them. Our method proposes the use of single RMSEA values to replace the choice of RMSEA pairs for model comparison and power analysis, thus avoiding the differential meaning of the chosen RMSEA pairs inherent in the approach of MacCallum et al. (2006). With this choice, the conventional cutoff values in model overall evaluation can directly be transferred and applied to the evaluation and power analysis of model differences. © 2011 American Psychological Association

Modelling of electron beam induced nanowire attraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bitzer, Lucas A.; Benson, Niels, E-mail: niels.benson@uni-due.de; Schmechel, Roland

2016-04-14

Scanning electron microscope (SEM) induced nanowire (NW) attraction or bundling is a well known effect, which is mainly ascribed to structural or material dependent properties. However, there have also been recent reports of electron beam induced nanowire bending by SEM imaging, which is not fully explained by the current models, especially when considering the electro-dynamic interaction between NWs. In this article, we contribute to the understanding of this phenomenon, by introducing an electro-dynamic model based on capacitor and Lorentz force interaction, where the active NW bending is stimulated by an electromagnetic force between individual wires. The model includes geometrical, electrical,more » and mechanical NW parameters, as well as the influence of the electron beam source parameters and is validated using in-situ observations of electron beam induced GaAs nanowire (NW) bending by SEM imaging.« less

A simple method for detection of gunshot residue particles from hands, hair, face, and clothing using scanning electron microscopy/wavelength dispersive X-ray (SEM/WDX).

PubMed

Kage, S; Kudo, K; Kaizoji, A; Ryumoto, J; Ikeda, H; Ikeda, N

2001-07-01

We devised a simple and rapid method for detection of gunshot residue (GSR) particles, using scanning electron microscopy/wavelength dispersive X-ray (SEM/WDX) analysis. Experiments were done on samples containing GSR particles obtained from hands, hair, face, and clothing, using double-sided adhesive coated aluminum stubs (tape-lift method). SEM/WDX analyses for GSR were carried out in three steps: the first step was map analysis for barium (Ba) to search for GSR particles from lead styphnate primed ammunition, or tin (Sn) to search for GSR particles from mercury fulminate primed ammunition. The second step was determination of the location of GSR particles by X-ray imaging of Ba or Sn at a magnification of x 1000-2000 in the SEM, using data of map analysis, and the third step was identification of GSR particles, using WDX spectrometers. Analysis of samples from each primer of a stub took about 3 h. Practical applications were shown for utility of this method.

Crumb Rubber Recycling in Enhancing Damping Properties of Concrete

NASA Astrophysics Data System (ADS)

Sugapriya, P.; Ramkrishnan, R.

2018-02-01

Damping plays a major role in the design of roadside structures that gets affected due to vibrations transmitted from moving traffic. In this study, fine aggregates were partially replaced with crumb rubber in concrete, at varying percentages of 5, 10, 15 and 20% by weight. Three different sets of concrete, mixed with crumb rubber were prepared using raw rubber, treated rubber and treated rubber with partial replacement of cement. Cement was partially replaced with Ultra-Fine Ground Granulated Blast furnace Slag (UFGGBS) for this study. Samples were cast, cured and tested for various properties on the 7th and 28th day. The damping ratio and frequency of the peak value from a number of waves in rubber incorporated beams were found out using a FFT Analyser along with its Strength, Damping and Sorptivity characteristics. SEM analysis was conducted to analyse the micro structural bonding between rubber and concrete. The mode shapes of pavement slabs were modelled and analysed using a FEM tool, ANSYS. From the results, the behaviour of the three sets of rubberized concrete were compared and analysed, and an optimum percentage for crumb rubber and UFGGBS was proposed to achieve best possible damping without compromising the strength properties.

Eudaimonic Well-Being and Tumor Norepinephrine in Epithelial Ovarian Cancer Patients

PubMed Central

Davis, Lauren Z.; Slavich, George M.; Thaker, Premal H.; Goodheart, Michael J.; Bender, David; Dahmoush, Laila; Farley, Donna; Markon, Kristian; Penedo, Frank J.; Lubaroff, David M.; Cole, Steve W.; Sood, Anil K.; Lutgendorf, Susan K.

2015-01-01

Background The impact of psychological well-being on physiologic processes involved in cancer progression remains unclear. Prior research has implicated adrenergic signaling in tumor growth and metastasis. Given that adrenergic signaling is influenced by both positive and negative factors, we examined how two different aspects of well-being (eudaimonic and positive affect) and psychological distress were associated with tumor norepinephrine (NE) in ovarian cancer patients. Methods Women with suspected ovarian cancer (N=365) completed psychosocial assessments pre-surgery and clinical information was obtained from medical records. Study inclusion was confirmed following histological diagnosis. Tumor NE was measured in frozen tissue samples using HPLC with electrochemical detection. We employed confirmatory factor analysis to model eudaimonic well-being, positive affect, and psychological distress, and structural equation modeling (SEM) to examine associations between these factors and tumor NE. Results Eudaimonic well-being, positive affect, and psychological distress, modeled as distinct but correlated constructs, best fit the data (i.e., compared to unitary or 2-factor models) (RMSEA=.048, CFI=.982, SRMR=.035). SEM analyses that included physical well-being, stage, histology, psychological treatment history, beta-blocker use, and caffeine use as covariates had good model fit (RMSEA=.052, CFI=.955, SRMR=.036) and showed that eudaimonic well-being was related to lower tumor NE (β=−.24, p=.045). In contrast, we found no effects for positive affect or psychological distress. Conclusion Eudaimonic well-being is associated with lower tumor NE, independent of positive affect and psychological distress. Because adrenergic signaling is implicated in tumor progression, increasing eudaimonic well-being may improve both psychological and physiologic resilience in ovarian cancer patients. PMID:26096769

Thrombogenesis with continuous blood flow in the inferior vena cava. A novel mouse model.

PubMed

Diaz, José A; Hawley, Angela E; Alvarado, Christine M; Berguer, Alexandra M; Baker, Nichole K; Wrobleski, Shirley K; Wakefield, Thomas W; Lucchesi, Benedict R; Myers, Daniel D

2010-08-01

Several rodent models have been used to study deep venous thrombosis (DVT). However, a model that generates consistent venous thrombi in the presence of continuous blood flow, to evaluate therapeutic agents for DVT, is not available. Mice used in the present study were wild-type C57BL/6 (WT), plasminogen activator inhibitor-1 (PAI-1) knock out (KO) and Delta Cytoplasmic Tail (DCT). An electrolytic inferior vena cava (IVC) model (EIM) was used. A 25G stainless-steel needle, attached to a silver coated copper wire electrode (anode), was inserted into the exposed caudal IVC. Another electrode (cathode) was placed subcutaneously. A current of 250 muAmps over 15 minutes was applied. Ultrasound imaging was used to demonstrate the presence of IVC blood flow. Analyses included measurement of plasma soluble P-selectin (sP-Sel), thrombus weight (TW), vein wall morphometrics, P-selectin and Von Willebrand factor (vWF) staining, transmission electron microscopy (TEM), scanning electron microscopy (SEM); and the effect of enoxaparin on TW was evaluated. A current of 250 muAmps over 15 minutes consistently promoted thrombus formation in the IVC. Plasma sP-Sel was decreased in PAI-1 KO and increased in DCT vs. WT (WT/PAI-1: p=0.003, WT/DCT: p=0.0002). Endothelial activation was demonstrated by SEM, TEM, P-selectin and vWF immunohistochemistry and confirmed by inflammatory cell counts. Ultrasound imaging demonstrated thrombus formation in the presence of blood flow. Enoxaparin significantly reduced the thrombus size by 61% in this model. This EIM closely mimics clinical venous disease and can be used to study endothelial cell activation, leukocyte migration, thrombogenesis and therapeutic applications in the presence of blood flow.

Fitting direct covariance structures by the MSTRUCT modeling language of the CALIS procedure.

PubMed

Yung, Yiu-Fai; Browne, Michael W; Zhang, Wei

2015-02-01

This paper demonstrates the usefulness and flexibility of the general structural equation modelling (SEM) approach to fitting direct covariance patterns or structures (as opposed to fitting implied covariance structures from functional relationships among variables). In particular, the MSTRUCT modelling language (or syntax) of the CALIS procedure (SAS/STAT version 9.22 or later: SAS Institute, 2010) is used to illustrate the SEM approach. The MSTRUCT modelling language supports a direct covariance pattern specification of each covariance element. It also supports the input of additional independent and dependent parameters. Model tests, fit statistics, estimates, and their standard errors are then produced under the general SEM framework. By using numerical and computational examples, the following tests of basic covariance patterns are illustrated: sphericity, compound symmetry, and multiple-group covariance patterns. Specification and testing of two complex correlation structures, the circumplex pattern and the composite direct product models with or without composite errors and scales, are also illustrated by the MSTRUCT syntax. It is concluded that the SEM approach offers a general and flexible modelling of direct covariance and correlation patterns. In conjunction with the use of SAS macros, the MSTRUCT syntax provides an easy-to-use interface for specifying and fitting complex covariance and correlation structures, even when the number of variables or parameters becomes large. © 2014 The British Psychological Society.

Treatment of social approach processes in adults with social anxiety disorder.

PubMed

Alden, Lynn E; Buhr, Kristin; Robichaud, Melisa; Trew, Jennifer L; Plasencia, M Leili

2018-06-01

Despite the social impairment associated with social anxiety disorder (SAD), little research has examined the impact of treatment on positive relational functioning. Accordingly, the authors conducted a treatment outcome study to evaluate a cognitive behavior therapy (CBT) regimen augmented by a relational focus (CBT-R) relative to a graduated exposure-applied relaxation (GEAR) regimen and wait list (WL) control. To examine the mechanism(s) that underlies treatment effects, they used structural equation modeling (SEM) to evaluate two potential mediators, change in judgment biases and in safety behaviors. Treatment-seeking adults who met SAD diagnostic criteria (n = 100; 50% women; mean age = 32.9 years.; 36% ethnic minority) were randomly assigned to CBT-R, GEAR, or WL. CBT-R and GEAR participants received 14 group treatment sessions. Social initiation, relationship satisfaction, and a SAD symptom composite were assessed at pre- and postassessment, and 6- and 12-month follow-ups. Intent-to-treat multilevel modeling analyses indicated that the CBT-R regimen resulted in significantly greater improvement relative to GEAR on relationship satisfaction and SAD symptoms. SEM results revealed that change in safety behaviors partially mediated the superior performance of CBT-R on both variables with confidence intervals set at .90. These findings indicate that CBT-based regimens can improve social approach processes in individuals with SAD and that safety behavior reduction contributes to positive outcomes. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Measuring quantitative autism traits in families: informant effect or intergenerational transmission?

PubMed

De la Marche, Wouter; Noens, Ilse; Kuppens, Sofie; Spilt, Jantine L; Boets, Bart; Steyaert, Jean

2015-04-01

Autism spectrum disorders (ASD) have a high degree of heritability, but there is still much debate about specific causal genes and pathways. To gain insight into patterns of transmission, research has focused on the relatedness of quantitative autism traits (QAT) between family members, mostly using questionnaires. Yet, different kinds of bias may influence research results. In this paper, we focus on possible informant effects and, taking these into account, on possible intergenerational transmission of QAT. This study used multiple informant data retrieved via the Social Responsiveness Scale from 170 families with at least one member with ASD. Using intraclass correlations (ICCs) and mixed model analyses, we investigated inter-informant agreement and differences between parent and teacher reports on children and between self- and other-reports on adults. Using structural equation modelling (SEM), we investigated the relatedness of QAT between family members in ASD families. Parent-teacher agreement about social responsiveness was poor, especially for children with ASD, though agreement between parents was moderate to strong for affected and unaffected children. Agreement between self- and other-report in adult men was good, but only moderate in women. Agreement did not differ between adults with and without ASD. While accounting for informant effects, our SEM results corroborated the assortative mating theory and the intergenerational transmission of QAT from both fathers and mothers to their offspring.

Effects of thermal cycling parameters on residual stresses in alumina scales of CoNiCrAlY and NiCoCrAlY bond coats

DOE PAGES

Nordhorn, Christian; Mücke, Robert; Unocic, Kinga A.; ...

2014-08-20

In this paper, furnace cycling experiments were performed on free-standing high-velocity oxygen-fuel bond coat samples to investigate the effect of material composition, surface texture, and cycling conditions on the average stresses in the formed oxide scales after cooling. The oxide scale thicknesses were determined by SEM image analyses and information about the stresses were acquired by photo-stimulated luminescence-spectroscopy. Additionally, the scale thickness dependent stress fields were calculated in finite-element analyses including approximation functions for the surface roughness derived on the basis of profilometry data. The evolution of the average residual stress as a function of oxide scale thickness was subjectmore » to stochastic fluctuations predominantly caused by local scale spallations. In comparison to the supplemental modeling results, thermal stresses due to mismatch of thermal expansion coefficients are identified as the main contribution to the residual stresses. Finally, the theoretical results emphasize that analyses of spectroscopic data acquired for average stress investigations of alumina scales rely on detailed information about microstructural features.« less

The Influence of the Sport Education Model on Amotivated Students' In-Class Physical Activity

ERIC Educational Resources Information Center

Perlman, Dana

2012-01-01

The Sport Education Model (SEM) was designed by Siedentop to provide students with a holistic sport-based experience. As research on the SEM continues, an aspect that has gained interest is the influence on (a) students with low levels of motivation and (b) opportunities to engage in health-enhancing levels of physical activity. The purpose of…

Case Studies of Successful Schoolwide Enrichment Model-Reading (SEM-R) Classroom Implementations. Research Monograph Series. RM10204

ERIC Educational Resources Information Center

Reis, Sally M.; Little, Catherine A.; Fogarty, Elizabeth; Housand, Angela M.; Housand, Brian C.; Sweeny, Sheelah M.; Eckert, Rebecca D.; Muller, Lisa M.

2010-01-01

The purpose of this qualitative study was to examine the scaling up of the Schoolwide Enrichment Model in Reading (SEM-R) in 11 elementary and middle schools in geographically diverse sites across the country. Qualitative comparative analysis was used in this study, with multiple data sources compiled into 11 in-depth school case studies…

Classroom versus Societal Willingness to Communicate: Investigating French as a Second Language in Flanders

ERIC Educational Resources Information Center

Denies, Katrijn; Yashima, Tomoko; Janssen, Rianne

2015-01-01

This study investigates willingness to communicate (WTC) and its determinants through structural equation modelling (SEM). Building on models by MacIntyre and Charos (1996) and Yashima (2002), it addresses 3 apparent gaps in the current knowledge base: It is the first SEM-based WTC study in a Western European context, investigating French as a…

A Simulation of the Topographic Contrast in the SEM

NASA Astrophysics Data System (ADS)

Kotera, Masatoshi; Fujiwara, Takafumi; Suga, Hiroshi; Wittry, David B.

1990-10-01

A simulation model is presented to analyze the topographic contast in the scanning electron microscope (SEM). This simulation takes into account all major mechanisms from signal generation to signal detection in the SEM. The calculated result shows that the resolution of the secondary electron image is better than that of the backscattered electron image for 1 and 3 keV primary electrons incident on an Al target. An asymmetric intensity profile of a signal at a topographic pattern, usually found in the SEM equipped with the Everhart-Thornley detector, is mainly due to the asymmetric profile of the backscattered electron signal.

A hybrid method for the computation of quasi-3D seismograms.

NASA Astrophysics Data System (ADS)

Masson, Yder; Romanowicz, Barbara

2013-04-01

The development of powerful computer clusters and efficient numerical computation methods, such as the Spectral Element Method (SEM) made possible the computation of seismic wave propagation in a heterogeneous 3D earth. However, the cost of theses computations is still problematic for global scale tomography that requires hundreds of such simulations. Part of the ongoing research effort is dedicated to the development of faster modeling methods based on the spectral element method. Capdeville et al. (2002) proposed to couple SEM simulations with normal modes calculation (C-SEM). Nissen-Meyer et al. (2007) used 2D SEM simulations to compute 3D seismograms in a 1D earth model. Thanks to these developments, and for the first time, Lekic et al. (2011) developed a 3D global model of the upper mantle using SEM simulations. At the local and continental scale, adjoint tomography that is using a lot of SEM simulation can be implemented on current computers (Tape, Liu et al. 2009). Due to their smaller size, these models offer higher resolution. They provide us with images of the crust and the upper part of the mantle. In an attempt to teleport such local adjoint tomographic inversions into the deep earth, we are developing a hybrid method where SEM computation are limited to a region of interest within the earth. That region can have an arbitrary shape and size. Outside this region, the seismic wavefield is extrapolated to obtain synthetic data at the Earth's surface. A key feature of the method is the use of a time reversal mirror to inject the wavefield induced by distant seismic source into the region of interest (Robertsson and Chapman 2000). We compute synthetic seismograms as follow: Inside the region of interest, we are using regional spectral element software RegSEM to compute wave propagation in 3D. Outside this region, the wavefield is extrapolated to the surface by convolution with the Green's functions from the mirror to the seismic stations. For now, these Green's functions are computed using 2D SEM simulation in a 1D Earth model. Such seismograms account for the 3D structure inside the region of interest in a quasi-exact manner. Later we plan to extrapolate the misfit function computed from such seismograms at the stations back into the SEM region in order to compute local adjoint kernels. This opens a new path toward regional adjoint tomography into the deep Earth. Capdeville, Y., et al. (2002). "Coupling the spectral element method with a modal solution for elastic wave propagation in global Earth models." Geophysical Journal International 152(1): 34-67. Lekic, V. and B. Romanowicz (2011). "Inferring upper-mantle structure by full waveform tomography with the spectral element method." Geophysical Journal International 185(2): 799-831. Nissen-Meyer, T., et al. (2007). "A two-dimensional spectral-element method for computing spherical-earth seismograms-I. Moment-tensor source." Geophysical Journal International 168(3): 1067-1092. Robertsson, J. O. A. and C. H. Chapman (2000). "An efficient method for calculating finite-difference seismograms after model alterations." Geophysics 65(3): 907-918. Tape, C., et al. (2009). "Adjoint tomography of the southern California crust." Science 325(5943): 988-992.

Effects of gender, age, and diabetes duration on dietary self-care in adolescents with type 1 diabetes: a Self-Determination Theory perspective.

PubMed

Austin, Stéphanie; Senécal, Caroline; Guay, Frédéric; Nouwen, Arie

2011-09-01

This study tests a model derived from Self-Determination Theory (SDT) (Deci and Ryan, 2000) to explain the mechanisms by which non-modifiable factors influence dietary self-care in adolescents with type 1 diabetes (n = 289). SEM analyses adjusted for HbA1c levels revealed that longer diabetes duration and female gender were indicative of poorer dietary self-care. This effect was mediated by contextual and motivational factors as posited by SDT. Poorer autonomy support from practitioners was predominant in girls with longer diabetes duration. Perceived autonomous motivation and self-efficacy were indicative of greater autonomy support, and led to better dietary self-care.

Adsorption Isotherm of Chromium (Vi) into Zncl2 Impregnated Activated Carbon Derived by Jatropha Curcas Seed Hull

NASA Astrophysics Data System (ADS)

Mohammad, M.; Yakub, I.; Yaakob, Z.; Asim, N.; Sopian, K.

2017-12-01

Hexavalent chromium is carcinogenic and should be removed from industrial wastewater before discharged into water resources. Adsorption by using activated carbon from biomass is an economic and conventional way on removing the heavy metal ions from wastewater. In this research, activated carbon is synthesized from Jatropha curcas L. seed hull through chemical activation with ZnCl2 and carbonized at 800 °C (JAC/ZnCl2). The activated carbon has been characterized using FTIR, SEM-EDX, BET and CHNS-O analyzer. Adsorption isotherms have been analysed using Langmuir and Freundlich models to determine its removal mechanism. The maximum adsorption capacity of Cr (VI) metal ions onto JAC/ZnCl2 activated carbon is 25.189 mg/g and following Langmuir isotherm model which is monolayer adsorption.

Thermocatalytic Behavior of Manganese (IV) Oxide as Nanoporous Material on the Dissociation of a Gas Mixture Containing Hydrogen Peroxide

PubMed Central

Jildeh, Zaid B.; Kirchner, Patrick; Wagner, Patrick H.

2018-01-01

In this article, we present an overview on the thermocatalytic reaction of hydrogen peroxide (H2O2) gas on a manganese (IV) oxide (MnO2) catalytic structure. The principle of operation and manufacturing techniques are introduced for a calorimetric H2O2 gas sensor based on porous MnO2. Results from surface analyses by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) of the catalytic material provide indication of the H2O2 dissociation reaction schemes. The correlation between theory and the experiments is documented in numerical models of the catalytic reaction. The aim of the numerical models is to provide further information on the reaction kinetics and performance enhancement of the porous MnO2 catalyst. PMID:29690519

Electron microscopy and forensic practice

NASA Astrophysics Data System (ADS)

Kotrlý, Marek; Turková, Ivana

2013-05-01

Electron microanalysis in forensic practice ranks among basic applications used in investigation of traces (latents, stains, etc.) from crime scenes. Applying electron microscope allows for rapid screening and receiving initial information for a wide range of traces. SEM with EDS/WDS makes it possible to observe topography surface and morphology samples and examination of chemical components. Physical laboratory of the Institute of Criminalistics Prague use SEM especially for examination of inorganic samples, rarely for biology and other material. Recently, possibilities of electron microscopy have been extended considerably using dual systems with focused ion beam. These systems are applied mainly in study of inner micro and nanoparticles , thin layers (intersecting lines in graphical forensic examinations, analysis of layers of functional glass, etc.), study of alloys microdefects, creating 3D particles and aggregates models, etc. Automated mineralogical analyses are a great asset to analysis of mineral phases, particularly soils, similarly it holds for cathode luminescence, predominantly colour one and precise quantitative measurement of their spectral characteristics. Among latest innovations that are becoming to appear also at ordinary laboratories are TOF - SIMS systems and micro Raman spectroscopy with a resolution comparable to EDS/WDS analysis (capable of achieving similar level as through EDS/WDS analysis).

Combining the role of convenience and consideration set size in explaining fish consumption in Norway.

PubMed

Rortveit, Asbjorn Warvik; Olsen, Svein Ottar

2009-04-01

The purpose of this study is to explore how convenience orientation, perceived product inconvenience and consideration set size are related to attitudes towards fish and fish consumption. The authors present a structural equation model (SEM) based on the integration of two previous studies. The results of a SEM analysis using Lisrel 8.72 on data from a Norwegian consumer survey (n=1630) suggest that convenience orientation and perceived product inconvenience have a negative effect on both consideration set size and consumption frequency. Attitude towards fish has the greatest impact on consumption frequency. The results also indicate that perceived product inconvenience is a key variable since it has a significant impact on attitude, and on consideration set size and consumption frequency. Further, the analyses confirm earlier findings suggesting that the effect of convenience orientation on consumption is partially mediated through perceived product inconvenience. The study also confirms earlier findings suggesting that the consideration set size affects consumption frequency. Practical implications drawn from this research are that the seafood industry would benefit from developing and positioning products that change beliefs about fish as an inconvenient product. Future research for other food categories should be done to enhance the external validity.

Predictors of outcomes in patients undergoing covered and uncovered self-expandable metal stent placement for malignant gastric outlet obstruction: a multicenter study.

PubMed

Hori, Yasuki; Naitoh, Itaru; Hayashi, Kazuki; Ban, Tesshin; Natsume, Makoto; Okumura, Fumihiro; Nakazawa, Takahiro; Takada, Hiroki; Hirano, Atsuyuki; Jinno, Naruomi; Togawa, Shozo; Ando, Tomoaki; Kataoka, Hiromi; Joh, Takashi

2017-02-01

Uncovered self-expandable metal stents (U-SEMSs) and covered self-expandable metal stents (C-SEMSs) are available for palliative therapy for malignant gastric outlet obstruction (GOO). However, clinical differences and indications between the 2 types of SEMSs have not been elucidated. We retrospectively compared 126 patients with U-SEMS and 126 patients with C-SEMSs with regard to clinical outcome and factors predictive of clinical improvement after SEMSs placement. No significant difference was observed between the U-SEMS and C-SEMS groups with respect to technical success, clinical success, GOO score, or time to stent dysfunction. Stent migration was significantly more frequent in patients with C-SEMSs (U-SEMSs, .79%; C-SEMSs, 8.73%; P = .005). Karnofsky performance status, chemotherapy, peritoneal dissemination, and stent expansion ≤ 30% were associated significantly with poor GOO score improvement in multivariable analyses, but stent type was not (P = .213). In subgroup analyses, insufficient (≤30%) stent expansion was an independent factor in patients with U-SEMSs (P = .041) but not C-SEMSs. In the insufficient stent expansion subgroup, C-SEMSs was associated significantly with superior clinical improvement compared with U-SEMSs (P = .01). Insufficient stent expansion was observed more frequently in patients with GI obstruction because of anastomotic sites or metastatic cancer (44.8% [13/29], P = .001). No clinical difference, apart from stent migration, was observed between patients with U-SEMSs and C-SEMSs. GI obstruction because of an anastomotic site or metastatic cancer may be an indication for C-SEMS use to improve oral intake after SEMSs placement. Copyright © 2017 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.

Family Environment and Childhood Obesity: A New Framework with Structural Equation Modeling

PubMed Central

Huang, Hui; Wan Mohamed Radzi, Che Wan Jasimah bt; Salarzadeh Jenatabadi, Hashem

2017-01-01

The main purpose of the current article is to introduce a framework of the complexity of childhood obesity based on the family environment. A conceptual model that quantifies the relationships and interactions among parental socioeconomic status, family food security level, child’s food intake and certain aspects of parental feeding behaviour is presented using the structural equation modeling (SEM) concept. Structural models are analysed in terms of the direct and indirect connections among latent and measurement variables that lead to the child weight indicator. To illustrate the accuracy, fit, reliability and validity of the introduced framework, real data collected from 630 families from Urumqi (Xinjiang, China) were considered. The framework includes two categories of data comprising the normal body mass index (BMI) range and obesity data. The comparison analysis between two models provides some evidence that in obesity modeling, obesity data must be extracted from the dataset and analysis must be done separately from the normal BMI range. This study may be helpful for researchers interested in childhood obesity modeling based on family environment. PMID:28208833

Family Environment and Childhood Obesity: A New Framework with Structural Equation Modeling.

PubMed

Huang, Hui; Wan Mohamed Radzi, Che Wan Jasimah Bt; Salarzadeh Jenatabadi, Hashem

2017-02-13

The main purpose of the current article is to introduce a framework of the complexity of childhood obesity based on the family environment. A conceptual model that quantifies the relationships and interactions among parental socioeconomic status, family food security level, child's food intake and certain aspects of parental feeding behaviour is presented using the structural equation modeling (SEM) concept. Structural models are analysed in terms of the direct and indirect connections among latent and measurement variables that lead to the child weight indicator. To illustrate the accuracy, fit, reliability and validity of the introduced framework, real data collected from 630 families from Urumqi (Xinjiang, China) were considered. The framework includes two categories of data comprising the normal body mass index (BMI) range and obesity data. The comparison analysis between two models provides some evidence that in obesity modeling, obesity data must be extracted from the dataset and analysis must be done separately from the normal BMI range. This study may be helpful for researchers interested in childhood obesity modeling based on family environment.

Change in Affect and Needs Satisfaction for Amotivated Students within the Sport Education Model

ERIC Educational Resources Information Center

Perlman, Dana

2010-01-01

The purpose of this study is to examine the influence of the Sport Education Model ("SEM") on amotivated students affect and needs satisfaction. 78 amotivated students from an original pool of 1,176 students enrolled in one of 32 physical education classes. Classes were randomly assigned to either the "SEM" (N = 16)or traditional class (N = 16).…

Situational Effects May Account for Gain Scores in Cognitive Ability Testing: A Longitudinal SEM Approach

ERIC Educational Resources Information Center

Matton, Nadine; Vautier, Stephane; Raufaste, Eric

2009-01-01

Mean gain scores for cognitive ability tests between two sessions in a selection setting are now a robust finding, yet not fully understood. Many authors do not attribute such gain scores to an increase in the target abilities. Our approach consists of testing a longitudinal SEM model suitable to this view. We propose to model the scores' changes…

Review of Sample Size for Structural Equation Models in Second Language Testing and Learning Research: A Monte Carlo Approach

ERIC Educational Resources Information Center

In'nami, Yo; Koizumi, Rie

2013-01-01

The importance of sample size, although widely discussed in the literature on structural equation modeling (SEM), has not been widely recognized among applied SEM researchers. To narrow this gap, we focus on second language testing and learning studies and examine the following: (a) Is the sample size sufficient in terms of precision and power of…

Crystal growth and characterization of bulk Sb2Te3 topological insulator

NASA Astrophysics Data System (ADS)

Sultana, Rabia; Gurjar, Ganesh; Patnaik, S.; Awana, V. P. S.

2018-04-01

The Sb2Te3 crystals are grown using the conventional self flux method via solid state reaction route, by melting constituent elements (Sb and Te) at high temperature (850 °C), followed by slow cooling (2 °C/h). As grown Sb2Te3 crystals are analysed for various physical properties by x-ray diffraction (XRD), Raman Spectroscopy, Scanning Electron Microscopy (SEM) coupled with Energy Dispersive x-ray Spectroscopy (EDAX) and electrical measurements under magnetic field (6 Tesla) down to low temperature (2.5 K). The XRD pattern revealed the growth of synthesized Sb2Te3 sample along (00l) plane, whereas the SEM along with EDAX measurements displayed the layered structure with near stoichiometric composition, without foreign contamination. The Raman scattering studies displayed known ({{{{A}}}1{{g}}}1, {{{{E}}}{{g}}}2 and {{{{A}}}1{{g}}}2) vibrational modes for the studied Sb2Te3. The temperature dependent electrical resistivity measurements illustrated the metallic nature of the as grown Sb2Te3 single crystal. Further, the magneto—transport studies represented linear positive magneto-resistance (MR) reaching up to 80% at 2.5 K under an applied field of 6 Tesla. The weak anti localization (WAL) related low field (±2 Tesla) magneto-conductance at low temperatures (2.5 K and 20 K) has been analysed and discussed using the Hikami—Larkin—Nagaoka (HLN) model. Summarily, the short letter reports an easy and versatile method for crystal growth of bulk Sb2Te3 topological insulator (TI) and its brief physical property characterization.

Representing general theoretical concepts in structural equation models: The role of composite variables

USGS Publications Warehouse

Grace, J.B.; Bollen, K.A.

2008-01-01

Structural equation modeling (SEM) holds the promise of providing natural scientists the capacity to evaluate complex multivariate hypotheses about ecological systems. Building on its predecessors, path analysis and factor analysis, SEM allows for the incorporation of both observed and unobserved (latent) variables into theoretically-based probabilistic models. In this paper we discuss the interface between theory and data in SEM and the use of an additional variable type, the composite. In simple terms, composite variables specify the influences of collections of other variables and can be helpful in modeling heterogeneous concepts of the sort commonly of interest to ecologists. While long recognized as a potentially important element of SEM, composite variables have received very limited use, in part because of a lack of theoretical consideration, but also because of difficulties that arise in parameter estimation when using conventional solution procedures. In this paper we present a framework for discussing composites and demonstrate how the use of partially-reduced-form models can help to overcome some of the parameter estimation and evaluation problems associated with models containing composites. Diagnostic procedures for evaluating the most appropriate and effective use of composites are illustrated with an example from the ecological literature. It is argued that an ability to incorporate composite variables into structural equation models may be particularly valuable in the study of natural systems, where concepts are frequently multifaceted and the influence of suites of variables are often of interest. ?? Springer Science+Business Media, LLC 2007.

The Interface Between Theory and Data in Structural Equation Models

USGS Publications Warehouse

Grace, James B.; Bollen, Kenneth A.

2006-01-01

Structural equation modeling (SEM) holds the promise of providing natural scientists the capacity to evaluate complex multivariate hypotheses about ecological systems. Building on its predecessors, path analysis and factor analysis, SEM allows for the incorporation of both observed and unobserved (latent) variables into theoretically based probabilistic models. In this paper we discuss the interface between theory and data in SEM and the use of an additional variable type, the composite, for representing general concepts. In simple terms, composite variables specify the influences of collections of other variables and can be helpful in modeling general relationships of the sort commonly of interest to ecologists. While long recognized as a potentially important element of SEM, composite variables have received very limited use, in part because of a lack of theoretical consideration, but also because of difficulties that arise in parameter estimation when using conventional solution procedures. In this paper we present a framework for discussing composites and demonstrate how the use of partially reduced form models can help to overcome some of the parameter estimation and evaluation problems associated with models containing composites. Diagnostic procedures for evaluating the most appropriate and effective use of composites are illustrated with an example from the ecological literature. It is argued that an ability to incorporate composite variables into structural equation models may be particularly valuable in the study of natural systems, where concepts are frequently multifaceted and the influences of suites of variables are often of interest.

The Applicability of Standard Error of Measurement and Minimal Detectable Change to Motor Learning Research-A Behavioral Study.

PubMed

Furlan, Leonardo; Sterr, Annette

2018-01-01

Motor learning studies face the challenge of differentiating between real changes in performance and random measurement error. While the traditional p -value-based analyses of difference (e.g., t -tests, ANOVAs) provide information on the statistical significance of a reported change in performance scores, they do not inform as to the likely cause or origin of that change, that is, the contribution of both real modifications in performance and random measurement error to the reported change. One way of differentiating between real change and random measurement error is through the utilization of the statistics of standard error of measurement (SEM) and minimal detectable change (MDC). SEM is estimated from the standard deviation of a sample of scores at baseline and a test-retest reliability index of the measurement instrument or test employed. MDC, in turn, is estimated from SEM and a degree of confidence, usually 95%. The MDC value might be regarded as the minimum amount of change that needs to be observed for it to be considered a real change, or a change to which the contribution of real modifications in performance is likely to be greater than that of random measurement error. A computer-based motor task was designed to illustrate the applicability of SEM and MDC to motor learning research. Two studies were conducted with healthy participants. Study 1 assessed the test-retest reliability of the task and Study 2 consisted in a typical motor learning study, where participants practiced the task for five consecutive days. In Study 2, the data were analyzed with a traditional p -value-based analysis of difference (ANOVA) and also with SEM and MDC. The findings showed good test-retest reliability for the task and that the p -value-based analysis alone identified statistically significant improvements in performance over time even when the observed changes could in fact have been smaller than the MDC and thereby caused mostly by random measurement error, as opposed to by learning. We suggest therefore that motor learning studies could complement their p -value-based analyses of difference with statistics such as SEM and MDC in order to inform as to the likely cause or origin of any reported changes in performance.

A New Look at Genetic and Environmental Architecture on Lipids Using Non-Normal Structural Equation Modeling in Male Twins: The NHLBI Twin Study.

PubMed

Wu, Sheng-Hui; Ozaki, Koken; Reed, Terry; Krasnow, Ruth E; Dai, Jun

2017-07-01

This study examined genetic and environmental influences on the lipid concentrations of 1028 male twins using the novel univariate non-normal structural equation modeling (nnSEM) ADCE and ACE models. In the best fitting nnSEM ADCE model that was also better than the nnSEM ACE model, additive genetic factors (A) explained 4%, dominant genetic factors (D) explained 17%, and common (C) and unique (E) environmental factors explained 47% and 33% of the total variance of high-density lipoprotein cholesterol (HDL-C). The percentage of variation explained for other lipids was 0% (A), 30% (D), 34% (C) and 37% (E) for low-density lipoprotein cholesterol (LDL-C); 30, 0, 31 and 39% for total cholesterol; and 0, 31, 12 and 57% for triglycerides. It was concluded that additive and dominant genetic factors simultaneously affected HDL-C concentrations but not other lipids. Common and unique environmental factors influenced concentrations of all lipids.

The ultrastructure of mono- and holocentric plant centromeres: an immunological investigation by structured illumination microscopy and scanning electron microscopy.

PubMed

Wanner, Gerhard; Schroeder-Reiter, Elizabeth; Ma, Wei; Houben, Andreas; Schubert, Veit

2015-12-01

The spatial distribution of the three centromere-associated proteins α-tubulin, CENH3, and phosphorylated histone H2A (at threonine 120, H2AThr120ph) was analysed by indirect immunodetection at monocentric cereal chromosomes and at the holocentric chromosomes of Luzula elegans by super-resolution light microscopy and scanning electron microscopy (SEM). Using structured illumination microscopy (SIM) as the super-resolution technique on squashed specimens and SEM on uncoated isolated specimens, the three-dimensional (3D) distribution of the proteins was visualized at the centromeres. Technical aspects of 3D SEM are explained in detail. We show that CENH3 forms curved "pads" mainly around the lateral centromeric region in the primary constriction of metacentric chromosomes. H2AThr120ph is present in both the primary constriction and in the pericentromere. α-tubulin-labeled microtubule bundles attach to CENH3-containing chromatin structures, either in single bundles with a V-shaped attachment to the centromere or in split bundles to bordering pericentromeric flanks. In holocentric L. elegans chromosomes, H2AThr120ph is located predominantly in the centromeric groove of each chromatid as proven by subsequent FIB/FESEM ablation and 3D reconstruction. α-tubulin localizes to the edges of the groove. In both holocentric and monocentric chromosomes, no additional intermediate structures between microtubules and the centromere were observed. We established models of the distribution of CENH3, H2AThr120ph and the attachment sites of microtubules for metacentric and holocentric plant chromosomes.

Dimensions of disinhibited personality and their relation with alcohol use and problems

PubMed Central

Gunn, Rachel L.; Finn, Peter R.; Endres, Michael J.; Gerst, Kyle R.; Spinola, Suzanne

2013-01-01

Although alcohol use disorders (AUDs) have been associated with different aspects of disinhibited personality and antisociality, less is known about the specific relationships among different domains of disinhibited personality, antisociality, alcohol use, and alcohol problems. The current study was designed to address three goals, (i) to provide evidence of a three-factor model of disinhibited personality (comprised of impulsivity [IMP], risk taking/ low harm avoidance [RTHA], excitement seeking [ES]), (ii) to test hypotheses regarding the association between each dimension and alcohol use and problems, and (iii) to test the hypothesis that antisociality (social deviance proneness [SDP]) accounts for the direct association between IMP and alcohol problems, while ES is directly related to alcohol use. Measures of disinhibited personality IMP, RTHA, ES and SDP and alcohol use and problems were assessed in a sample of young adults (N=474), which included a high proportion of individuals with AUDs. Confirmatory factor analyses supported a three-factor model of disinhibited personality reflecting IMP, RTHA, and ES. A structural equation model (SEM) showed that IMP was specifically associated with alcohol problems, while ES was specifically associated with alcohol use. In a second SEM, SDP accounted for the majority of the variance in alcohol problems associated with IMP. The results suggest aspects of IMP associated with SDP represent a direct vulnerability to alcohol problems. In addition, the results suggest that ES reflects a specific vulnerability to excessive alcohol use, which is then associated with alcohol problems, while RTHA is not specifically associated with alcohol use or problems when controlling for IMP and ES. PMID:23588138

The detection of metallic residues in skin stab wounds by means of SEM-EDS: A pilot study.

PubMed

Palazzo, Elisa; Amadasi, Alberto; Boracchi, Michele; Gentile, Guendalina; Maciocco, Francesca; Marchesi, Matteo; Zoja, Riccardo

2018-05-01

The morphological analysis of stab wounds may often not be accurate enough to link it with the type of wounding weapon, but a further evaluation may be performed with the search for metallic residues left during the contact between the instrument and the skin. In this study, Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) was applied to the study of cadaveric stab wounds performed with kitchen knives composed of iron, chromium and nickel, in order to verify the presence of metallic residues on the wound's edge. Two groups of 10 corpses were selected: group A, including victims of stab wounds and a control group B (died of natural causes). Samplings were performed on the lesions and in intact areas of group A, whereas in group B sampling were performed in non-exposed intact skin. Samples were then analysed with optical microscopy and SEM-EDS. In group A, optical microscopic analysis showed the presence of vital haemorrhagic infiltration, while SEM-EDS showed evidence of microscopic metal traces, isolated or clustered, consisting of iron, chromium and nickel. Moreover, in two cases organic residues of calcium and phosphate were detected, as a probable sign of bone lesion. Control samples (group A in intact areas and group B), were negative for the search of exogenous material to optical microscopy and SEM-EDS. The results show the utility and possible application of the SEM-EDS in theidentification of metallic residues from sharp weapons on the skin. Copyright © 2017 The Chartered Society of Forensic Sciences. Published by Elsevier B.V. All rights reserved.

Counting Synapses Using FIB/SEM Microscopy: A True Revolution for Ultrastructural Volume Reconstruction.

PubMed

Merchán-Pérez, Angel; Rodriguez, José-Rodrigo; Alonso-Nanclares, Lidia; Schertel, Andreas; Defelipe, Javier

2009-01-01

The advent of transmission electron microscopy (TEM) in the 1950s represented a fundamental step in the study of neuronal circuits. The application of this technique soon led to the realization that the number of synapses changes during the course of normal life, as well as under certain pathological or experimental circumstances. Since then, one of the main goals in neurosciences has been to define simple and accurate methods to estimate the magnitude of these changes. Contrary to analysing single sections, TEM reconstructions are extremely time-consuming and difficult. Therefore, most quantitative studies use stereological methods to define the three-dimensional characteristics of synaptic junctions that are studied in two dimensions. Here, to count the exact number of synapses per unit of volume we have applied a new three-dimensional reconstruction method that involves the combination of focused ion beam milling and scanning electron microscopy (FIB/SEM). We show that the images obtained with FIB/SEM are similar to those obtained with TEM, but with the advantage that FIB/SEM permits serial reconstructions of large volumes of tissue to be generated rapidly and automatically. Furthermore, we compared the estimates of the number of synapses obtained with stereological methods with the values obtained by FIB/SEM reconstructions. We concluded that FIB/SEM not only provides the actual number of synapses per volume but it is also much easier and faster to use than other currently available TEM methods. More importantly, it also avoids most of the errors introduced by stereological methods and overcomes the difficulties associated with these techniques.

Laboratory batch experiments and geochemical modelling of water-rock-supercritical CO2 reactions in Southern San Joaquin Valley, California oil field sediments: Implications for future carbon capture and sequestration projects.

NASA Astrophysics Data System (ADS)

Mickler, P. J.; Rivas, C.; Freeman, S.; Tan, T. W.; Baron, D.; Horton, R. A.

2015-12-01

Storage of CO2 as supercritical liquid in oil reservoirs has been proposed for enhanced oil recovery and a way to lower atmospheric CO2 levels. The fate of CO2 after injection requires an understanding of mineral dissolution/precipitation reactions occurring between the formation minerals and the existing formation brines at formation temperatures and pressures in the presence of supercritical CO2. In this study, core samples from three potential storage formations, the Vedder Fm. (Rio Bravo oil field), Stevens Fm. (Elk Hills oil field) and Temblor Fm. (McKittrick oil field) were reacted with a synthetic brine and CO2(sc) at reservoir temperature (110°C) and pressure (245-250 bar). A combination of petrographic, SEM-EDS and XRD analyses, brine chemistry, and PHREEQ-C modelling were used to identify geochemical reactions altering aquifer mineralogy. XRD and petrographic analyses identified potentially reactive minerals including calcite and dolomite (~2%), pyrite (~1%), and feldspars (~25-60%). Despite the low abundance, calcite dissolution and pyrite oxidation were dominant geochemical reactions. Feldspar weathering produced release rates ~1-2 orders of magnitude slower than calcite dissolution. Calcite dissolution increased the aqueous concentrations of Ca, HCO3, Mg, Mn and Sr. Silicate weathering increased the aqueous concentrations of Si and K. Plagioclase weathering likely increased aqueous Ca concentrations. Pyrite oxidation, despite attempts to remove O2 from the experiment, increased the aqueous concentration of Fe and SO4. SEM-EDS analysis of post-reaction samples identified mixed-layered illite-smectites associated with feldspar grains suggesting clay mineral precipitation in addition to calcite, pyrite and feldspar dissolution. The Vedder Fm. sample underwent complete disaggregation during the reaction due to cement dissolution. This may adversely affect Vedder Formation CCS projects by impacting injection well integrity.

Electrophoretic Deposition of Chitosan/45S5 Bioactive Glass Composite Coatings Doped with Zn and Sr

PubMed Central

Miola, Marta; Verné, Enrica; Ciraldo, Francesca Elisa; Cordero-Arias, Luis; Boccaccini, Aldo R.

2015-01-01

In this research work, the original 45S5 bioactive glass was modified by introducing zinc and/or strontium oxide (6 mol%) in place of calcium oxide. Sr was added for its ability to stimulate bone formation and Zn for its role in bone metabolism, antibacterial properties, and anti-inflammatory effect. The glasses were produced by means of melting and quenching process. SEM and XRD analyses evidenced that Zr and Sr introduction did not modify the glass structure and morphology while compositional analysis (EDS) demonstrated the effective incorporation of these elements in the glass network. Bioactivity test in simulated body fluid (SBF) up to 1 month evidenced a reduced bioactivity kinetics for Zn-doped glasses. Doped glasses were combined with chitosan to produce organic/inorganic composite coatings on stainless steel AISI 316L by electrophoretic deposition (EPD). Two EPD processes were considered for coating development, namely direct current EPD (DC-EPD) and alternating current EPD (AC-EPD). The stability of the suspension was analyzed and the deposition parameters were optimized. Tape and bending tests demonstrated a good coating-substrate adhesion for coatings containing 45S5-Sr and 45S5-ZnSr glasses, whereas the adhesion to the substrate decreased by using 45S5-Zn glass. FTIR analyses demonstrated the composite nature of coatings and SEM observations indicated that glass particles were well integrated in the polymeric matrix, the coatings were fairly homogeneous and free of cracks; moreover, the AC-EPD technique provided better results than DC-EPD in terms of coating quality. SEM, XRD analyses, and Raman spectroscopy, performed after bioactivity test in SBF solution, confirmed the bioactive behavior of 45S5-Sr-containing coating while coatings containing Zn exhibited no hydroxyapatite formation. PMID:26539431

SEM-EDX analysis in the source apportionment of particulate matter on Hypogymnia physodes lichen transplants around the Cu smelter and former mining town of Karabash, South Urals, Russia.

PubMed

Williamson, B J; Mikhailova, I; Purvis, O W; Udachin, V

2004-04-25

Scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX) of particulate matter on lichen transplant thalli (Hypogymnia physodes) was assessed as a complementary technique to wet chemical analysis for source apportionment of airborne contaminants. Transplants (2 month exposure) stationed in the Cu smelter and former mining town of Karabash were compared with those from a control site 30 km south. Particulate matter in Karabash samples (715 analyses) showed higher levels of S, Pb, Cu, Sn and Zn compared with the control (598 analyses). Complex element associations among the particles confounded detailed mineralogical identifications, and therefore a simplified particle classification scheme was devised for source apportionment. Karabash samples contained high levels of particles classified as mining-related (MRP), and these were also identified in control samples, indicating wide spatial dispersion from the smelter and highlighting the sensitivity of the method. It was noted that MRP <2.5-microm diameter were poorly represented on lichen surfaces suggesting this may limit the usefulness of Hypogymnia transplants as proxies when assessing human health impacts from airborne particulates. Analyses of the lichen thallus surface (away from surface particulates) revealed high levels of Cu, Zn, Fe and Pb associated with organics in the Karabash samples compared with the control, with a proportionate loss of K, interpreted as being due to a stress-related increase in cell membrane permeability. This type of analysis may provide a novel SEM-EDX-based method for assessing lichen vitality. The techniques developed are presented and further implications of the study are discussed.

Scanning electron microscopy and X-ray energy dispersive spectroscopy - useful tools in the analysis of pharmaceutical products

NASA Astrophysics Data System (ADS)

Sarecka-Hujar, Beata; Balwierz, Radoslaw; Ostrozka-Cieslik, Aneta; Dyja, Renata; Lukowiec, Dariusz; Jankowski, Andrzej

2017-11-01

The quality of the drug, its purity and identification of degradation products provide the highest quality of pharmaceutical products. The energy dispersive spectroscopy (EDS) method analyses the percentage of each element form as well as their distribution, and morphological characteristics of the drug form. We analysed the usefulness of EDS method in testing orally disintegrating tablets (ODT) with trimetazidine hydrochloride with high resolution scanning electron microscopy (SEM, SUPRA25 Carl Zeiss company) with spectrophotometer equipped with an X-ray energy dispersion (EDAX Company). The samples of the analysed tablets were imaged after applying conductive layers of gold on their surface. In the EDS analysis the compositions of each sample of the obtained tablets were observed to be virtually identical. The differences in the content of carbon and oxygen came from differences in the composition of particular tablets. The presence of gold in the composition resulted from the sputtering the surface of tablets with gold during the analysis. Knowing the composition of the tablet, SEM-EDS method helps to locate and identify the impurities and degradation products of the compounds, leading to a better understanding of the mechanisms of their formation.

Glycolysis of carbon fiber-epoxy unidirectional mat catalysed by sodium hydroxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zaini, Mariana Binti Mohd; Badri, Khairiah Haji

2014-09-03

This study was conducted to recycle carbon fibre-epoxy (CFRP) composite in woven sheet/ mat form. The CFRP was recycled through glycolysis with polyethlyene glycol (PEG 200) as the solvent. The CFRP was loaded into the solvent at a ratio of 4:1 (w/w). PEG200 was diluted with water to a ratio of 80:20 (v/v). This reaction was catalysed by sodium hydroxide (NaOH) solution with varying concentrations at 1.5, 1.7 and 1.9% (w/v). The glycolysis was conducted at 180-190 °C. The recovered CF (rCF) was analysed using Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX) while themore » degraded solution was analysed using FTIR and the epoxy content was determined. The FTIR spectrum of the rCF exhibited the disappearance of the COC peak belonged to epoxy and supported by the SEM micrographs that showed clear rCF. On the other hand, the analysed filtrate detected the disappearance of oxygen peak element in the EDX spectrum for all rCF samples. This gave an indication that the epoxy resin has been removed from the surface of the carbon fiber.« less

Glycolysis of carbon fiber-epoxy unidirectional mat catalysed by sodium hydroxide

NASA Astrophysics Data System (ADS)

Zaini, Mariana Binti Mohd; Badri, Khairiah Haji

2014-09-01

This study was conducted to recycle carbon fibre-epoxy (CFRP) composite in woven sheet/ mat form. The CFRP was recycled through glycolysis with polyethlyene glycol (PEG 200) as the solvent. The CFRP was loaded into the solvent at a ratio of 4:1 (w/w). PEG200 was diluted with water to a ratio of 80:20 (v/v). This reaction was catalysed by sodium hydroxide (NaOH) solution with varying concentrations at 1.5, 1.7 and 1.9% (w/v). The glycolysis was conducted at 180-190 °C. The recovered CF (rCF) was analysed using Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX) while the degraded solution was analysed using FTIR and the epoxy content was determined. The FTIR spectrum of the rCF exhibited the disappearance of the COC peak belonged to epoxy and supported by the SEM micrographs that showed clear rCF. On the other hand, the analysed filtrate detected the disappearance of oxygen peak element in the EDX spectrum for all rCF samples. This gave an indication that the epoxy resin has been removed from the surface of the carbon fiber.

Determinants of biosecurity behaviour of British cattle and sheep farmers-a behavioural economics analysis.

PubMed

Toma, Luiza; Stott, Alistair W; Heffernan, Claire; Ringrose, Siân; Gunn, George J

2013-03-01

The paper analyses the impact of a priori determinants of biosecurity behaviour of farmers in Great Britain. We use a dataset collected through a stratified telephone survey of 900 cattle and sheep farmers in Great Britain (400 in England and a further 250 in Wales and Scotland respectively) which took place between 25 March 2010 and 18 June 2010. The survey was stratified by farm type, farm size and region. To test the influence of a priori determinants on biosecurity behaviour we used a behavioural economics method, structural equation modelling (SEM) with observed and latent variables. SEM is a statistical technique for testing and estimating causal relationships amongst variables, some of which may be latent using a combination of statistical data and qualitative causal assumptions. Thirteen latent variables were identified and extracted, expressing the behaviour and the underlying determining factors. The variables were: experience, economic factors, organic certification of farm, membership in a cattle/sheep health scheme, perceived usefulness of biosecurity information sources, knowledge about biosecurity measures, perceived importance of specific biosecurity strategies, perceived effect (on farm business in the past five years) of welfare/health regulation, perceived effect of severe outbreaks of animal diseases, attitudes towards livestock biosecurity, attitudes towards animal welfare, influence on decision to apply biosecurity measures and biosecurity behaviour. The SEM model applied on the Great Britain sample has an adequate fit according to the measures of absolute, incremental and parsimonious fit. The results suggest that farmers' perceived importance of specific biosecurity strategies, organic certification of farm, knowledge about biosecurity measures, attitudes towards animal welfare, perceived usefulness of biosecurity information sources, perceived effect on business during the past five years of severe outbreaks of animal diseases, membership in a cattle/sheep health scheme, attitudes towards livestock biosecurity, influence on decision to apply biosecurity measures, experience and economic factors are significantly influencing behaviour (overall explaining 64% of the variance in behaviour). Three other models were run for the individual regions (England, Scotland and Wales). A smaller number of variables were included in each model to account for the smaller sample sizes. Results show lower but still high levels of variance explained for the individual models (about 40% for each country). The individual models' results are consistent with those of the total sample model. The results might suggest that ways to achieve behavioural change could include ensuring increased access of farmers to biosecurity information and advice sources. Copyright © 2012 Elsevier B.V. All rights reserved.

Development of 1500mm Wide Wrought Magnesium Alloys by Twin Roll Casting Technique in Turkey

NASA Astrophysics Data System (ADS)

Duygulu, Ozgur; Ucuncuoglu, Selda; Oktay, Gizem; Temur, Deniz Sultan; Yucel, Onuralp; Kaya, Ali Arslan

Magnesium alloy AZ31, AZ61, AZ91, AM50 and AM60 sheets were produced by twin roll casting first time in Turkey. Sheets of 4.5-6.5mm thick and 1500mm width were successfully achieved. Microstructure of the sheet was analyzed by optical microscope, scanning electron microscope (SEM) and transmission electron microscope (TEM). Semi-quantitative analyses were performed by SEM-EDS. In addition, X-ray studies were performed for both characterization and texture purposes. Mechanical properties were investigated by tensile tests and also hardness measurements. Homogenization and annealing heat treatments were performed on the produced sheets.

Prophylometric and SEM analyses of four different finishing methods

PubMed Central

CHIODERA, G.; CERUTTI, F.; CERUTTI, A.; PUTIGNANO, A.; MANGANI, F.

2013-01-01

Summary Adhesion is the pivot of the modern restorative dentistry. Inlays, onlays and veneers have become a valid alternative to the traditional prosthetic treatments even in the rehabilitation of extremely damaged teeth, allowing a consistent saving of sound tooth tissues. Composite resins and dental adhesive are continously investigated and improved, nevertheless the optimization of the tooth-adhesive interface has to be considered: in fact, the long-term stability of adhesion between tooth and composite material depends on the treatment of the amelo-dentinal surfaces. This study investigated the quality of the occlusal walls of a cavity prepared to receive an inlay and finished with four different systems: thin and extra-thin diamond coated burs, a 12-blades carbide burs and a diamond-coated tip driven by sonic instrument. Consequently, prophylometric and SEM analyses were performed on the samples. The average roughness values recorded by the prophylometer were expressed by the parameters Ra and RZ: there is a correspondence between the numeric values and the pictures of the SEM. The results show a better quality (low roughness values) of the surface treated with multi-blade burs, followed by the this and extra-thin diamond coated burs. The 25 micron diamond-coated tip of the sonic instrument obtains the roughest surface and a sensibly higher amount of smear layer than the other tested systems. PMID:23741601

Influence of PCL on mechanical properties and bioactivity of ZrO2-based hybrid coatings synthesized by sol-gel dip coating technique.

PubMed

Catauro, Michelina; Bollino, Flavia; Veronesi, Paolo; Lamanna, Giuseppe

2014-06-01

The biological properties of medical implants can be enhanced through surface modifications such as to provide a firm attachment of the implant. In this study, organic-inorganic hybrid coatings have been synthesized via sol-gel dip coating. They consist of an inorganic ZrO2 matrix in which different amounts of poly(ε-caprolactone) have been entrapped to improve the mechanical properties of the films. The influence of the PCL amount on the microstructural, biological and mechanical properties of the coating has been investigated. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses have shown that the hybrids used for the coating are homogenous and totally amorphous materials; Fourier transform infrared spectroscopy (FT-IR) has demonstrated that hydrogen bonds arise between the organic and inorganic phases. SEM and atomic force microscopy (AFM) have highlighted the nanostructured nature of the film. SEM and EDS analyses, after soaking the samples in a simulated body fluid (SBF), have pointed out the apatite formation on the coating surface, which proves the bone-bonding ability of the nanocomposite bioactive films. Scratch and nano-indentation tests have shown that the coating hardness, stiffness and Young's modulus decrease in the presence of large amounts of the organic phase. Copyright © 2014. Published by Elsevier B.V.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Li; Zhu, Zihua; Yu, Xiao-Ying

In this study, we report new results of in situ study of 5 nm goat anti-mouse IgG gold nanoparticles in a novel portable vacuum compatible microfluidic device using scanning electron microscope (SEM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The unique feature of the liquid flow cell is that the detection window is open to the vacuum allowing direct probing of the liquid surface. The flow cell is composed of a silicon nitride (SiN) membrane and polydimethylsiloxane (PDMS), and it is fully compatible with vacuum operations for surface analysis. The aperture can be drilled through the 100 nm SiN membranemore » using a focused ion beam. Characteristic signals of the conjugated gold nanoparticles were successfully observed through the aperture by both energy-dispersive X-ray spectroscopy (EDX) in SEM and ToF-SIMS. Comparison was also made among wet samples, dry samples, and liquid sample in the flow cell using SEM/EDX. Stronger gold signal can be observed in our novel portable device by SEM/EDX compared with the wet or dry samples, respectively. Our results indicate that analyses of the nanoparticle components are better made in their native liquid environment. This is made possible using our unique microfluidic flow cell.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beckingham, Lauren E.; Peters, Catherine A.; Um, Wooyong

Although the impact of subsurface geochemical reactions on porosity is relatively well understood, changes in permeability remain difficult to estimate. In this work, pore-network modeling was used to predict permeability based on pore- and pore-throat size distributions determined from analysis of 2D scanning electron microscopy (SEM) images of thin sections and 3D X-ray computed microtomography (CMT) data. The analyzed specimens were a Viking sandstone sample from the Alberta sedimentary basin and an experimental column of reacted Hanford sediments. For the column, a decrease in permeability due to mineral precipitation was estimated, but the permeability estimates were dependent on imaging techniquemore » and resolution. X-ray CT imaging has the advantage of reconstructing a 3D pore network while 2D SEM imaging can easily analyze sub-grain and intragranular variations in mineralogy. Pore network models informed by analyses of 2D and 3D images at comparable resolutions produced permeability esti- mates with relatively good agreement. Large discrepancies in predicted permeabilities resulted from small variations in image resolution. Images with resolutions 0.4 to 4 lm predicted permeabilities differ- ing by orders of magnitude. While lower-resolution scans can analyze larger specimens, small pore throats may be missed due to resolution limitations, which in turn overestimates permeability in a pore-network model in which pore-to-pore conductances are statistically assigned. Conversely, high-res- olution scans are capable of capturing small pore throats, but if they are not actually flow-conducting predicted permeabilities will be below expected values. In addition, permeability is underestimated due to misinterpreting surface-roughness features as small pore throats. Comparison of permeability pre- dictions with expected and measured permeability values showed that the largest discrepancies resulted from the highest resolution images and the best predictions of permeability will result from images between 2 and 4 lm resolution. To reduce permeability underestimation from analyses of high-resolu- tion images, a resolution threshold between 3 and 15 lm was found to be effective, but it is not known whether this range is applicable beyond the samples studied here.« less

Spectroscopic, microchemical and petrographic analyses of plasters from ancient buildings in Lamezia Terme (Calabria, Southern Italy)

NASA Astrophysics Data System (ADS)

De Luca, Raffaella; Gigliotti, Valentina; Panarello, Mario; Bloise, Andrea; Crisci, Gino M.; Miriello, Domenico

2016-01-01

This work shows the results of the spectroscopic, microchemical and petrographic study carried out on six plasters coming from three important residential buildings of the 18th century, located in Lamezia Terme (Catanzaro, Southern Italy). To study the provenance of the raw materials used to make the plasters, one sample of limestone and two samples of sand were also collected from the quarries near Lamezia Terme and compared with the historical plasters. Samples were studied by polarized optical microscopy (OM), X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) and Raman spectroscopy. The results of these analyses allowed to determine the mineralogical, petrographical and chemical characteristics of the plasters, identify the pigments used for their coloration and provide useful information about the building techniques, the raw materials employed and the production technology of plasters during the 18th century in Lamezia Terme. SEM-EDS microanalysis also revealed the presence of gold and silver on the surface of two samples.

Observation of Live Ticks (Haemaphysalis flava) by Scanning Electron Microscopy under High Vacuum Pressure

PubMed Central

Ishigaki, Yasuhito; Nakamura, Yuka; Oikawa, Yosaburo; Yano, Yasuhiro; Kuwabata, Susumu; Nakagawa, Hideaki; Tomosugi, Naohisa; Takegami, Tsutomu

2012-01-01

Scanning electron microscopes (SEM), which image sample surfaces by scanning with an electron beam, are widely used for steric observations of resting samples in basic and applied biology. Various conventional methods exist for SEM sample preparation. However, conventional SEM is not a good tool to observe living organisms because of the associated exposure to high vacuum pressure and electron beam radiation. Here we attempted SEM observations of live ticks. During 1.5×10−3 Pa vacuum pressure and electron beam irradiation with accelerated voltages (2–5 kV), many ticks remained alive and moved their legs. After 30-min observation, we removed the ticks from the SEM stage; they could walk actively under atmospheric pressure. When we tested 20 ticks (8 female adults and 12 nymphs), they survived for two days after SEM observation. These results indicate the resistance of ticks against SEM observation. Our second survival test showed that the electron beam, not vacuum conditions, results in tick death. Moreover, we describe the reaction of their legs to electron beam exposure. These findings open the new possibility of SEM observation of living organisms and showed the resistance of living ticks to vacuum condition in SEM. These data also indicate, for the first time, the usefulness of tick as a model system for biology under extreme condition. PMID:22431980

A new way of measuring wiggling pattern in SADP for 3D NAND technology

NASA Astrophysics Data System (ADS)

Mi, Jian; Chen, Ziqi; Tu, Li Ming; Mao, Xiaoming; Liu, Gong Cai; Kawada, Hiroki

2018-03-01

A new metrology method of quantitatively measuring wiggling patterns in a Self-Aligned Double Patterning (SADP) process for 2D NAND technology has been developed with a CD-SEM metrology program on images from a Review-SEM system. The metrology program provided accurate modeling of various wiggling patterns. The Review-SEM system provided a-few-micrometer-wide Field of View (FOV), which exceeds precision-guaranteed FOV of a conventional CD-SEM. The result has been effectively verified by visual inspection on vertically compressed images compared with Wiggling Index from this new method. A best-known method (BKM) system has been developed with connected HW and SW to automatically measure wiggling patterns.

Changes in the labour market and health inequalities during the years of the recent economic downturn in Italy.

PubMed

Sarti, Simone; Zella, Sara

2016-05-01

There is widespread concern that episodes of unemployment and unstable working conditions adversely affect health. We add to the debate by focusing on the relationship between work trajectory and the self-reported health of Italian men and women during the present economic downturn. Relying on Italian data in the EU-SILC project (from 2007 to 2010), our sample includes all individuals aged 30 to 60 in 2010, and uses multivariate binomial regression models for preliminary analyses and the Structural Equations modelling (SEM) to observe the cumulative effects of health status according to different job trajectories. Our main findings show similar pictures for men and women. Individuals who are unemployed, ejected or in precarious occupational positions have a higher risk of worsening their health status during these years. Copyright © 2016 Elsevier Inc. All rights reserved.

Improving lead adsorption through chemical modification of wheat straw by lactic acid

NASA Astrophysics Data System (ADS)

Mu, Ruimin; Wang, Minxiang; Bu, Qingwei; Liu, Dong; Zhao, Yanli

2018-01-01

This work describes the creation of a new cellulosic material derived from wheat straw modified by lactic acid for adsorption of lead in aqueous solution, called 0.3LANS (the concentration of the lactic acid were 0.3mol/L). Batch experiments were conducted to study the effects of initial pH value, contact time, adsorbent dose, initial concentration and temperature. Fourier transform infrared (FTIR), Elemental analysis, BET surface area and Scanning electron micrographs (SEM) analysis were used to investigate the chemical modification. Adsorption isotherm models namely, Langmuir, Freundlich were used to analyse the equilibrium data, and the Langmuir isotherm model provided the best correlation, means that the adsorption was chemical monolayer adsorption and the adsorption capacity qm was increased with increasing temperature, and reached 51.49mg/g for 0.3LANS at 35°C, showing adsorption was exothermic.

Posttraumatic Stress Disorder Symptoms, Relationship Adjustment, and Relationship Aggression in a Sample of Female Flood Victims

PubMed Central

Monson, Candice M.; Schumm, Jeremiah A.; Watkins, Laura E.; Panuzio, Jillian; Resick, Patricia A.

2010-01-01

This study tested a model examining the interrelationships among posttraumatic stress disorder (PTSD) symptoms, intimate relationship adjustment, and intimate relationship aggression in a sample of 205 adult female flood victims. At the bivariate level, higher PTSD symptoms were associated with higher physical and psychological aggression victimization, poorer relationship adjustment, and higher physical and psychological aggression perpetration. Results from structural equation modeling (SEM) analyses indicated that relationship aggression victimization influenced aggression perpetration directly, and in the case of physical aggression, indirectly through its relationship with PTSD symptoms and relationship adjustment. The influence of PTSD symptoms on physical aggression perpetration was fully explained by poorer relationship adjustment. These findings extend prior work from other traumatized populations documenting associations between variables reflecting PTSD symptomatology and indices of relationship functioning, and indicate a need for further investigation in this area of inquiry. PMID:21057584

The relationship between use of sexually explicit media and sexual risk behavior in men who have sex with men: exploring the mediating effects of sexual self-esteem and condom use self-efficacy

PubMed Central

Træen, Bente; Hald, Gert Martin; Noor, Syed W.; Iantaffi, Alex; Grey, Jeremy; Rosser, B. R. Simon

2014-01-01

This study tests the following three hypotheses: 1) there is a direct association between consumption of sexually explicit media (SEM) depicting non-condom use and STI-related sexual risk behavior among men who have sex with men (MSM), 2) The association between SEM consumption and STI-related sexual risk behavior is mediated by men’s sexual self-esteem, and 3) the relationship between SEM consumption and sexual risk behavior is mediated by condom use self-efficacy. A cross-sectional, Internet-based survey on exposure to SEM and sexual behavior of 1,391 MSM in the USA was conducted in 2011. The results confirmed hypothesis 1 and 3 while hypothesis 2 was rejected. Accordingly, a significant association between the use of SEM picturing condom use and STI related sexual risk behavior among MSM was found. Likewise, we found that the association between the use of SEM and sexual risk behavior was mediated by condom use self-efficacy in an indirect path. However, SEM did not influence sexual risk behavior via sexual self-esteem. To promote STI prevention, the actors in SEM may be used as role models in managing condom use in sexual contexts. PMID:24904709

AxiSEM3D: a new fast method for global wave propagation in 3-D Earth models with undulating discontinuities

NASA Astrophysics Data System (ADS)

Leng, K.; Nissen-Meyer, T.; van Driel, M.; Al-Attar, D.

2016-12-01

We present a new, computationally efficient numerical method to simulate global seismic wave propagation in realistic 3-D Earth models with laterally heterogeneous media and finite boundary perturbations. Our method is a hybrid of pseudo-spectral and spectral element methods (SEM). We characterize the azimuthal dependence of 3-D wavefields in terms of Fourier series, such that the 3-D equations of motion reduce to an algebraic system of coupled 2-D meridional equations, which can be solved by a 2-D spectral element method (based on www.axisem.info). Computational efficiency of our method stems from lateral smoothness of global Earth models (with respect to wavelength) as well as axial singularity of seismic point sources, which jointly confine the Fourier modes of wavefields to a few lower orders. All boundary perturbations that violate geometric spherical symmetry, including Earth's ellipticity, topography and bathymetry, undulations of internal discontinuities such as Moho and CMB, are uniformly considered by means of a Particle Relabeling Transformation.The MPI-based high performance C++ code AxiSEM3D, is now available for forward simulations upon 3-D Earth models with fluid outer core, ellipticity, and both mantle and crustal structures. We show novel benchmarks for global wave solutions in 3-D mantle structures between our method and an independent, fully discretized 3-D SEM with remarkable agreement. Performance comparisons are carried out on three state-of-the-art tomography models, with seismic period going down to 5s. It is shown that our method runs up to two orders of magnitude faster than the 3-D SEM for such settings, and such computational advantage scales favourably with seismic frequency. By examining wavefields passing through hypothetical Gaussian plumes of varying sharpness, we identify in model-wavelength space the limits where our method may lose its advantage.

An SAS Macro for Implementing the Modified Bollen-Stine Bootstrap for Missing Data: Implementing the Bootstrap Using Existing Structural Equation Modeling Software

ERIC Educational Resources Information Center

Enders, Craig K.

2005-01-01

The Bollen-Stine bootstrap can be used to correct for standard error and fit statistic bias that occurs in structural equation modeling (SEM) applications due to nonnormal data. The purpose of this article is to demonstrate the use of a custom SAS macro program that can be used to implement the Bollen-Stine bootstrap with existing SEM software.…

Structural equation modeling and natural systems

USGS Publications Warehouse

Grace, James B.

2006-01-01

This book, first published in 2006, presents an introduction to the methodology of structural equation modeling, illustrates its use, and goes on to argue that it has revolutionary implications for the study of natural systems. A major theme of this book is that we have, up to this point, attempted to study systems primarily using methods (such as the univariate model) that were designed only for considering individual processes. Understanding systems requires the capacity to examine simultaneous influences and responses. Structural equation modeling (SEM) has such capabilities. It also possesses many other traits that add strength to its utility as a means of making scientific progress. In light of the capabilities of SEM, it can be argued that much of ecological theory is currently locked in an immature state that impairs its relevance. It is further argued that the principles of SEM are capable of leading to the development and evaluation of multivariate theories of the sort vitally needed for the conservation of natural systems.

Motivation, strategy, and English as a foreign language vocabulary learning: A structural equation modelling study.

PubMed

Zhang, Yining; Lin, Chin-Hsi; Zhang, Dongbo; Choi, Yunjeong

2017-03-01

In spite of considerable advancements in our understanding of the different factors involved in achieving vocabulary-learning success, the overall pattern and interrelationships of critical factors involved in L2 vocabulary learning - particularly, the mechanisms through which learners regulate their motivation and learning strategies - remain unclear. This study examined L2 vocabulary learning, focusing on the joint influence of different motivational factors and learning strategies on the vocabulary breadth of adolescent learners of English as a foreign language (EFL) in China. The participants were 107 tenth graders (68 females, 39 males) in China. The data were collected via two questionnaires, one assessing students' motivation towards English-vocabulary learning and the other their English vocabulary-learning strategies, along with a test measuring vocabulary breadth. Structural equation modelling (SEM) indicated that learning strategy partially mediated the relationship between motivation (i.e., a composite score of intrinsic and extrinsic motivation) and vocabulary learning. Separate SEM analyses for intrinsic (IM) and extrinsic motivation (EM) revealed that there were significant and positive direct and indirect effects of IM on vocabulary knowledge; and while EM's direct effect over and above that of learning strategies did not achieve significance, its indirect effect was significant and positive. The findings suggest that vocabulary-learning strategies mediate the relationship between motivation and vocabulary knowledge. In addition, IM may have a greater influence on vocabulary learning in foreign-language contexts. © 2016 The British Psychological Society.

Residual depressive symptoms, sleep disturbance and perceived cognitive impairment as determinants of functioning in patients with bipolar disorder.

PubMed

Samalin, Ludovic; Boyer, Laurent; Murru, Andrea; Pacchiarotti, Isabella; Reinares, María; Bonnin, Caterina Mar; Torrent, Carla; Verdolini, Norma; Pancheri, Corinna; de Chazeron, Ingrid; Boucekine, Mohamed; Geoffroy, Pierre-Alexis; Bellivier, Frank; Llorca, Pierre-Michel; Vieta, Eduard

2017-03-01

Many patients with bipolar disorder (BD) experience residual symptoms during their inter-episodic periods. The study aimed to analyse the relationship between residual depressive symptoms, sleep disturbances and self-reported cognitive impairment as determinants of psychosocial functioning in a large sample of euthymic BD patients. This was a cross-sectional study of 468 euthymic BD outpatients. We evaluated the residual depressive symptoms with the Bipolar Depression Rating Scale, the sleep disturbances with the Pittsburgh Sleep Quality Index, the perceived cognitive performance using visual analogic scales and functioning with the Functioning Assessment Short Test. Structural equation modelling (SEM) was used to describe the relationships among the residual depressive symptoms, sleep disturbances, perceived cognitive performance and functioning. SEM showed good fit with normed chi square=2.46, comparative fit index=0.94, root mean square error of approximation=0.05 and standardized root mean square residuals=0.06. This model revealed that residual depressive symptoms (path coefficient =0.37) and perceived cognitive performance (path coefficient=0.27) were the most important features significantly related to psychosocial functioning. Sleep disturbances were indirectly associated with functioning via residual depressive symptoms and perceived cognitive performance (path coefficient=0.23). This study contributes to a better understanding of the determinants of psychosocial functioning during the inter-episodic periods of BD patients. These findings should facilitate decision-making in therapeutics to improve the functional outcomes of BD during this period. Copyright © 2017 Elsevier B.V. All rights reserved.

3D reconstruction of SEM images by use of optical photogrammetry software.

PubMed

Eulitz, Mona; Reiss, Gebhard

2015-08-01

Reconstruction of the three-dimensional (3D) surface of an object to be examined is widely used for structure analysis in science and many biological questions require information about their true 3D structure. For Scanning Electron Microscopy (SEM) there has been no efficient non-destructive solution for reconstruction of the surface morphology to date. The well-known method of recording stereo pair images generates a 3D stereoscope reconstruction of a section, but not of the complete sample surface. We present a simple and non-destructive method of 3D surface reconstruction from SEM samples based on the principles of optical close range photogrammetry. In optical close range photogrammetry a series of overlapping photos is used to generate a 3D model of the surface of an object. We adapted this method to the special SEM requirements. Instead of moving a detector around the object, the object itself was rotated. A series of overlapping photos was stitched and converted into a 3D model using the software commonly used for optical photogrammetry. A rabbit kidney glomerulus was used to demonstrate the workflow of this adaption. The reconstruction produced a realistic and high-resolution 3D mesh model of the glomerular surface. The study showed that SEM micrographs are suitable for 3D reconstruction by optical photogrammetry. This new approach is a simple and useful method of 3D surface reconstruction and suitable for various applications in research and teaching. Copyright © 2015 Elsevier Inc. All rights reserved.

Semantics-Based Composition of Integrated Cardiomyocyte Models Motivated by Real-World Use Cases.

PubMed

Neal, Maxwell L; Carlson, Brian E; Thompson, Christopher T; James, Ryan C; Kim, Karam G; Tran, Kenneth; Crampin, Edmund J; Cook, Daniel L; Gennari, John H

2015-01-01

Semantics-based model composition is an approach for generating complex biosimulation models from existing components that relies on capturing the biological meaning of model elements in a machine-readable fashion. This approach allows the user to work at the biological rather than computational level of abstraction and helps minimize the amount of manual effort required for model composition. To support this compositional approach, we have developed the SemGen software, and here report on SemGen's semantics-based merging capabilities using real-world modeling use cases. We successfully reproduced a large, manually-encoded, multi-model merge: the "Pandit-Hinch-Niederer" (PHN) cardiomyocyte excitation-contraction model, previously developed using CellML. We describe our approach for annotating the three component models used in the PHN composition and for merging them at the biological level of abstraction within SemGen. We demonstrate that we were able to reproduce the original PHN model results in a semi-automated, semantics-based fashion and also rapidly generate a second, novel cardiomyocyte model composed using an alternative, independently-developed tension generation component. We discuss the time-saving features of our compositional approach in the context of these merging exercises, the limitations we encountered, and potential solutions for enhancing the approach.

Semantics-Based Composition of Integrated Cardiomyocyte Models Motivated by Real-World Use Cases

PubMed Central

Neal, Maxwell L.; Carlson, Brian E.; Thompson, Christopher T.; James, Ryan C.; Kim, Karam G.; Tran, Kenneth; Crampin, Edmund J.; Cook, Daniel L.; Gennari, John H.

2015-01-01

Semantics-based model composition is an approach for generating complex biosimulation models from existing components that relies on capturing the biological meaning of model elements in a machine-readable fashion. This approach allows the user to work at the biological rather than computational level of abstraction and helps minimize the amount of manual effort required for model composition. To support this compositional approach, we have developed the SemGen software, and here report on SemGen’s semantics-based merging capabilities using real-world modeling use cases. We successfully reproduced a large, manually-encoded, multi-model merge: the “Pandit-Hinch-Niederer” (PHN) cardiomyocyte excitation-contraction model, previously developed using CellML. We describe our approach for annotating the three component models used in the PHN composition and for merging them at the biological level of abstraction within SemGen. We demonstrate that we were able to reproduce the original PHN model results in a semi-automated, semantics-based fashion and also rapidly generate a second, novel cardiomyocyte model composed using an alternative, independently-developed tension generation component. We discuss the time-saving features of our compositional approach in the context of these merging exercises, the limitations we encountered, and potential solutions for enhancing the approach. PMID:26716837

Formation of the Mont Dieu IIE Non Magmatic Iron Meteorite, and Origin of its Silicate Inclusions

NASA Astrophysics Data System (ADS)

van Roosbroek, N.; Goderis, S.; Debaille, V.; Valley, J. W.; Claeys, Ph.

2012-03-01

Mont Dieu is an IIE nonmagmatic iron meteorite showing primitive features such as preserved chondrules and glass. SEM and geochemical analyses demonstrate that it most likely originated from an H-chondrite parent body impacted by a Fe-Ni projectile.

The Norwegian version of the QOLIBRI - a study of metric properties based on a 12 month follow-up of persons with traumatic brain injury.

PubMed

Soberg, Helene Lundgaard; Roe, Cecilie; Brunborg, Cathrine; von Steinbüchel, Nicole; Andelic, Nada

2017-01-19

Consequences after Traumatic brain injury (TBI) affect the injured person's self-image and quality of life. The purpose was to assess the health related quality of life (HRQoL) at 12 months after a TBI in patients admitted to regional trauma centres, and to evaluate the metric properties of the Norwegian version of the Quality of Life After Brain Injury (QOLIBRI) questionnaire. Two hundred four patients with TBI of all severities were included. HRQoL at 12 months post-injury was measured by the QOLIBRI. It has a total scale and 6 subscales (satisfied with Cognition, Self, Daily Life and Autonomy and Social Relationships, and bothered by Emotions and Physical Problems). Demographic and injury related data were registered. Disability was registered by Glasgow Outcome Scale Extended (GOSE) and Rivermead Post-Concussion Questionnaire, and mental health by Hospital Anxiety and Depression Scale. Descriptive statistics, internal consistency by Cronbach's alpha and Corrected Item-Total Correlations were calculated. Rasch analysis, Principal Component Analysis (PCA) and Structural Equation Modelling (SEM) were applied. Mean age was 37.6 (SD 15.4) years; 72% were men, and 41% had higher education. Over 60% were severely injured. Mean Glasgow Coma Scale score was 9.3 (SD 4.5). According to the GOSE 5.9% had severe disability, 45.5% had moderate disability, and 48.5% had good recovery at 12 months post-injury. The QOLIBRI scales had a high internal consistency (α = 0.75-0.96), and only Physical Problems had an α < 0.85. In the Rasch analysis all subscales and their items fit the Rasch model, except for the depression item in the Emotion subscale. PCA and SEM analyses supported a six-factor structure in a second-order latent model. The QOLIBRI supports an underlying unidimensional HRQoL model. The SEM model fit statistics of the second-order model indicated a moderate fit to the observed data (CFI = 0.86, TLI = 0.85, RMSEA = 0.076, SRMR = 0.061, χ 2  = 1315.76, df = 623, p-value < 0.001). The Norwegian QOLIBRI has favourable psychometric properties, but there were some weaknesses related to its measurement properties of the total score when tested on a TBI population where many had severe TBI, and many had good recovery.

Clinimetric properties of the Nepali version of the Pain Catastrophizing Scale in individuals with chronic pain

PubMed Central

Thibault, Pascal; Abbott, J Haxby; Jensen, Mark P

2018-01-01

Background Pain catastrophizing is an exaggerated negative cognitive response related to pain. It is commonly assessed using the Pain Catastrophizing Scale (PCS). Translation and validation of the scale in a new language would facilitate cross-cultural comparisons of the role that pain catastrophizing plays in patient function. Purpose The aim of this study was to translate and culturally adapt the PCS into Nepali (Nepali version of PCS [PCS-NP]) and evaluate its clinimetric properties. Methods We translated, cross-culturally adapted, and performed an exploratory factor analysis (EFA) of the PCS-NP in a sample of adults with chronic pain (N=143). We then confirmed the resulting factor model in a separate sample (N=272) and compared this model with 1-, 2-, and 3-factor models previously identified using confirmatory factor analyses (CFAs). We also computed internal consistencies, test–retest reliabilities, standard error of measurement (SEM), minimal detectable change (MDC), and limits of agreement with 95% confidence interval (LOA95%) of the PCS-NP scales. Concurrent validity with measures of depression, anxiety, and pain intensity was assessed by computing Pearson’s correlation coefficients. Results The PCS-NP was comprehensible and culturally acceptable. We extracted a two-factor solution using EFA and confirmed this model using CFAs in the second sample. Adequate fit was also found for a one-factor model and different two- and three-factor models based on prior studies. The PCS-NP scores evidenced excellent reliability and temporal stability, and demonstrated validity via moderate-to-strong associations with measures of depression, anxiety, and pain intensity. The SEM and MDC for the PCS-NP total score were 2.52 and 7.86, respectively (range of PCS scores 0–52). LOA95% was between −15.17 and +16.02 for the total PCS-NP scores. Conclusion The PCS-NP is a valid and reliable instrument to assess pain catastrophizing in Nepalese individuals with chronic pain. PMID:29430196

Stent migration following endoscopic suture fixation of esophageal self-expandable metal stents: a systematic review and meta-analysis.

PubMed

Law, Ryan; Prabhu, Anoop; Fujii-Lau, Larissa; Shannon, Carol; Singh, Siddharth

2018-02-01

Covered self-expandable metal stents (SEMS) are utilized for the management of benign and malignant esophageal conditions; however, covered SEMS are prone to migration. Endoscopic suture fixation may mitigate the migration risk of covered esophageal SEMS. Hence, we conducted a systematic review and meta-analysis to evaluate the effectiveness and safety of endoscopic suture fixation for covered esophageal SEMS. Following PRISMA guidelines, we performed a systematic review from 2011 to 2016 to identify studies (case control/case series) reporting the technical success and migration rate of covered esophageal SEMS following endoscopic suture fixation. We searched multiple electronic databases and conference proceedings. We calculated pooled rates (and 95% confidence intervals [CI]) of technical success and stent migration using a random effects model. We identified 14 studies (212 patients) describing covered esophageal SEMS placement with endoscopic suture fixation. When reported, SEMS indications included leak/fistula (n = 75), stricture (n = 65), perforation (n = 10), and achalasia (n = 4). The pooled technical success rate was 96.7% (95% CI 92.3-98.6), without heterogeneity (I 2  = 0%). We identified 29 SEMS migrations at rate of 15.9% (95% CI 11.4-21.6), without heterogeneity (I 2  = 0%). Publication bias was observed, and using the trim-and-fill method, a more conservative estimate for stent migration was 17.0%. Suture-related adverse events were estimated to occur in 3.7% (95% CI 1.6-8.2) of cases. Endoscopic suture fixation of covered esophageal SEMS appears to reduce stent migration when compared to published rates of non-anchored SEMS. However, SEMS migration still occurs in approximately 1 out of 6 cases despite excellent immediate technical success and low risk of suture-related adverse events.

SEM-microphotogrammetry, a new take on an old method for generating high-resolution 3D models from SEM images.

PubMed

Ball, A D; Job, P A; Walker, A E L

2017-08-01

The method we present here uses a scanning electron microscope programmed via macros to automatically capture dozens of images at suitable angles to generate accurate, detailed three-dimensional (3D) surface models with micron-scale resolution. We demonstrate that it is possible to use these Scanning Electron Microscope (SEM) images in conjunction with commercially available software originally developed for photogrammetry reconstructions from Digital Single Lens Reflex (DSLR) cameras and to reconstruct 3D models of the specimen. These 3D models can then be exported as polygon meshes and eventually 3D printed. This technique offers the potential to obtain data suitable to reconstruct very tiny features (e.g. diatoms, butterfly scales and mineral fabrics) at nanometre resolution. Ultimately, we foresee this as being a useful tool for better understanding spatial relationships at very high resolution. However, our motivation is also to use it to produce 3D models to be used in public outreach events and exhibitions, especially for the blind or partially sighted. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Seeing a Mycobacterium-Infected Cell in Nanoscale 3D: Correlative Imaging by Light Microscopy and FIB/SEM Tomography

PubMed Central

Beckwith, Marianne Sandvold; Beckwith, Kai Sandvold; Sikorski, Pawel; Skogaker, Nan Tostrup

2015-01-01

Mycobacteria pose a threat to the world health today, with pathogenic and opportunistic bacteria causing tuberculosis and non-tuberculous disease in large parts of the population. Much is still unknown about the interplay between bacteria and host during infection and disease, and more research is needed to meet the challenge of drug resistance and inefficient vaccines. This work establishes a reliable and reproducible method for performing correlative imaging of human macrophages infected with mycobacteria at an ultra-high resolution and in 3D. Focused Ion Beam/Scanning Electron Microscopy (FIB/SEM) tomography is applied, together with confocal fluorescence microscopy for localization of appropriately infected cells. The method is based on an Aclar poly(chloro-tri-fluoro)ethylene substrate, micropatterned into an advantageous geometry by a simple thermomoulding process. The platform increases the throughput and quality of FIB/SEM tomography analyses, and was successfully applied to detail the intracellular environment of a whole mycobacterium-infected macrophage in 3D. PMID:26406896

Quantification of silver nanoparticle uptake and distribution within individual human macrophages by FIB/SEM slice and view.

PubMed

Guehrs, Erik; Schneider, Michael; Günther, Christian M; Hessing, Piet; Heitz, Karen; Wittke, Doreen; López-Serrano Oliver, Ana; Jakubowski, Norbert; Plendl, Johanna; Eisebitt, Stefan; Haase, Andrea

2017-03-21

Quantification of nanoparticle (NP) uptake in cells or tissues is very important for safety assessment. Often, electron microscopy based approaches are used for this purpose, which allow imaging at very high resolution. However, precise quantification of NP numbers in cells and tissues remains challenging. The aim of this study was to present a novel approach, that combines precise quantification of NPs in individual cells together with high resolution imaging of their intracellular distribution based on focused ion beam/ scanning electron microscopy (FIB/SEM) slice and view approaches. We quantified cellular uptake of 75 nm diameter citrate stabilized silver NPs (Ag 75 Cit) into an individual human macrophage derived from monocytic THP-1 cells using a FIB/SEM slice and view approach. Cells were treated with 10 μg/ml for 24 h. We investigated a single cell and found in total 3138 ± 722 silver NPs inside this cell. Most of the silver NPs were located in large agglomerates, only a few were found in clusters of fewer than five NPs. Furthermore, we cross-checked our results by using inductively coupled plasma mass spectrometry and could confirm the FIB/SEM results. Our approach based on FIB/SEM slice and view is currently the only one that allows the quantification of the absolute dose of silver NPs in individual cells and at the same time to assess their intracellular distribution at high resolution. We therefore propose to use FIB/SEM slice and view to systematically analyse the cellular uptake of various NPs as a function of size, concentration and incubation time.

Modelling and analysis of FMS productivity variables by ISM, SEM and GTMA approach

NASA Astrophysics Data System (ADS)

Jain, Vineet; Raj, Tilak

2014-09-01

Productivity has often been cited as a key factor in a flexible manufacturing system (FMS) performance, and actions to increase it are said to improve profitability and the wage earning capacity of employees. Improving productivity is seen as a key issue for survival and success in the long term of a manufacturing system. The purpose of this paper is to make a model and analysis of the productivity variables of FMS. This study was performed by different approaches viz. interpretive structural modelling (ISM), structural equation modelling (SEM), graph theory and matrix approach (GTMA) and a cross-sectional survey within manufacturing firms in India. ISM has been used to develop a model of productivity variables, and then it has been analyzed. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) are powerful statistical techniques. CFA is carried by SEM. EFA is applied to extract the factors in FMS by the statistical package for social sciences (SPSS 20) software and confirming these factors by CFA through analysis of moment structures (AMOS 20) software. The twenty productivity variables are identified through literature and four factors extracted, which involves the productivity of FMS. The four factors are people, quality, machine and flexibility. SEM using AMOS 20 was used to perform the first order four-factor structures. GTMA is a multiple attribute decision making (MADM) methodology used to find intensity/quantification of productivity variables in an organization. The FMS productivity index has purposed to intensify the factors which affect FMS.

Effects of acid-volatile sulfide on metal bioavailability and toxicity to midge (Chironomus tentans) larvae in black shale sediments

USGS Publications Warehouse

Ogendi, G.M.; Brumbaugh, W.G.; Hannigan, R.E.; Farris, J.L.

2007-01-01

Metal bioavailability and toxicity to aquatic organisms are greatly affected by variables such as pH, hardness, organic matter, and sediment acid-volatile sulfide (AVS). Sediment AVS, which reduces metal bioavailability and toxicity by binding and immobilizing metals as insoluble sulfides, has been studied intensely in recent years. Few studies, however, have determined the spatial variability of AVS and its interaction with simultaneously extracted metals (SEM) in sediments containing elevated concentrations of metals resulting from natural geochemical processes, such as weathering of black shales. We collected four sediment samples from each of four headwater bedrock streams in northcentral Arkansa (USA; three black shale-draining streams and one limestone-draining stream). We conducted 10-d acute whole-sediment toxicity tests using the midge Chironomus tentans and performed analyses for AVS, total metals, SEMs, and organic carbon. Most of the sediments from shale-draining streams had similar total metal and SEM concentrations but considerable differences in organic carbon and AVS. Zinc was the leading contributor to the SEM molar sum, averaging between 68 and 74%, whereas lead and cadmium contributed less than 3%. The AVS concentration was very low in all but two samples from one of the shale streams, and the sum of the SEM concentrations was in molar excess of AVS for all shale stream sediments. No significant differences in mean AVS concentrations between sediments collected from shale-draining or limestone-draining sites were noted (p > 0.05). Midge survival and growth in black shale-derived sediments were significantly less (p < 0.001) than that of limestone-derived sediments. On the whole, either SEM alone or SEM-AVS explained the total variation in midge survival and growth about equally well. However, survival and growth were significantly greater (p < 0.05) in the two sediment samples that contained measurable AVS compared with the two sediments from the same stream that contained negligible AVS. ?? 2007 SETAC.

Morphometric analyses of hominoid crania, probabilities of conspecificity and an approximation of a biological species constant.

PubMed

Thackeray, J F; Dykes, S

2016-02-01

Thackeray has previously explored the possibility of using a morphometric approach to quantify the "amount" of variation within species and to assess probabilities of conspecificity when two fossil specimens are compared, instead of "pigeon-holing" them into discrete species. In an attempt to obtain a statistical (probabilistic) definition of a species, Thackeray has recognized an approximation of a biological species constant (T=-1.61) based on the log-transformed standard error of the coefficient m (log sem) in regression analysis of cranial and other data from pairs of specimens of conspecific extant species, associated with regression equations of the form y=mx+c where m is the slope and c is the intercept, using measurements of any specimen A (x axis), and any specimen B of the same species (y axis). The log-transformed standard error of the co-efficient m (log sem) is a measure of the degree of similarity between pairs of specimens, and in this study shows central tendency around a mean value of -1.61 and standard deviation 0.10 for modern conspecific specimens. In this paper we focus attention on the need to take into account the range of difference in log sem values (Δlog sem or "delta log sem") obtained from comparisons when specimen A (x axis) is compared to B (y axis), and secondly when specimen A (y axis) is compared to B (x axis). Thackeray's approach can be refined to focus on high probabilities of conspecificity for pairs of specimens for which log sem is less than -1.61 and for which Δlog sem is less than 0.03. We appeal for the adoption of a concept here called "sigma taxonomy" (as opposed to "alpha taxonomy"), recognizing that boundaries between species are not always well defined. Copyright © 2015 Elsevier GmbH. All rights reserved.

Oceanic Whitecaps and Associated, Bubble-Mediated, Air-Sea Exchange Processes

DTIC Science & Technology

1992-10-01

experiments performed in laboratory conditions using Air-Sea Exchange Monitoring System (A-SEMS). EXPERIMENTAL SET-UP In a first look, the Air-Sea Exchange...Model 225, equipped with a Model 519 plug-in module. Other complementary information on A-SEMS along with results from first tests and calibration...between 9.50C and 22.40C within the first 24 hours after transferring the water sample into laboratory conditions. The results show an enhancement of

An energy-dispersive X-ray analysis and SEM study of debris remaining on endodontic instruments after ultrasonic cleaning and autoclave sterilization.

PubMed

Parirokh, Masoud; Asgary, Saeed; Eghbal, Mohammad Jafar

2005-08-01

This study was carried out to investigate metallic and non-metallic debris remaining on endodontic files after ultrasonic cleaning and autoclave processing. Forty-eight unused rotary and hand endodontic files, including eight different brands, were tested. Instruments were cleaned with ultrasound, autoclaved and before and after each step were observed by scanning electron microscopy (SEM). Adherent debris was analysed by energy-dispersive X-ray analysis (EDXA). All of the instruments before ultrasound cleaning were contaminated with metallic and non-metallic debris. Although most non-metallic debris was removed by ultrasonic cleaning, most of the metallic debris remained even after the final step of sterilization.

Mineralogical Features and REE Distribution in Ortho- and Clinopyroxenes of the HaH 317 Enstatite Chondrite

NASA Astrophysics Data System (ADS)

Moggi-Cecchi, V.; Pratesi, G.

2004-03-01

SEM, EMPA and LA-ICP-MS analyses have been performed on HaH 317, an EL4 enstatite chondrite. Phases detected are En, Kam, Tro, Dio, Pla, Nin, Old. Diopside and enstatite grains display similar REEs patterns with marked Ce and LREE enrichments.

Linking Structural Equation Modelling with Bayesian Network and Coastal Phytoplankton Dynamics in Bohai Bay

NASA Astrophysics Data System (ADS)

Chu, Jiangtao; Yang, Yue

2018-06-01

Bayesian networks (BN) have many advantages over other methods in ecological modelling and have become an increasingly popular modelling tool. However, BN are flawed in regard to building models based on inadequate existing knowledge. To overcome this limitation, we propose a new method that links BN with structural equation modelling (SEM). In this method, SEM is used to improve the model structure for BN. This method was used to simulate coastal phytoplankton dynamics in Bohai Bay. We demonstrate that this hybrid approach minimizes the need for expert elicitation, generates more reasonable structures for BN models and increases the BN model's accuracy and reliability. These results suggest that the inclusion of SEM for testing and verifying the theoretical structure during the initial construction stage improves the effectiveness of BN models, especially for complex eco-environment systems. The results also demonstrate that in Bohai Bay, while phytoplankton biomass has the greatest influence on phytoplankton dynamics, the impact of nutrients on phytoplankton dynamics is larger than the influence of the physical environment in summer. Furthermore, despite the Redfield ratio indicating that phosphorus should be the primary nutrient limiting factor, our results indicate that silicate plays the most important role in regulating phytoplankton dynamics in Bohai Bay.

Ilmenite exsolution schemes in Apollo-17 high-Ti basalts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vaniman, D.; Heiken, G.; Muhich, T.

1990-01-01

Combined electron microprobe and scanning electron microscope (SEM) x-ray image analyses are used to obtain semiquantitative data on the relations between ilmenite grains and their exsolved chromite and rutile. Comparisons of these data for ilmenites in four Apollo-17 high-Ti basalts with a database of electron microprobe analyses from the literature indicates that Cr expulsion from ilmenite can be as important as Fe{sup 2+} reduction in causing subsolidus exsolution of chromite and rutile from ilmenite. 12 refs., 4 figs., 5 tabs.

Reliability study of tibialis posterior and selected leg muscle EMG and multi-segment foot kinematics in rheumatoid arthritis associated pes planovalgus

PubMed Central

Barn, Ruth; Rafferty, Daniel; Turner, Deborah E.; Woodburn, James

2012-01-01

Objective To determine within- and between-day reliability characteristics of electromyographic (EMG) activity patterns of selected lower leg muscles and kinematic variables in patients with rheumatoid arthritis (RA) and pes planovalgus. Methods Five patients with RA underwent gait analysis barefoot and shod on two occasions 1 week apart. Fine-wire (tibialis posterior [TP]) and surface EMG for selected muscles and 3D kinematics using a multi-segmented foot model was undertaken barefoot and shod. Reliability of pre-determined variables including EMG activity patterns and inter-segment kinematics were analysed using coefficients of multiple correlation, intraclass correlation coefficients (ICC) and the standard error of the measurement (SEM). Results Muscle activation patterns within- and between-day ranged from fair-to-good to excellent in both conditions. Discrete temporal and amplitude variables were highly variable across all muscle groups in both conditions but particularly poor for TP and peroneus longus. SEMs ranged from 1% to 9% of stance and 4% to 27% of maximum voluntary contraction; in most cases the 95% confidence interval crossed zero. Excellent within-day reliability was found for the inter-segment kinematics in both conditions. Between-day reliability ranged from fair-to-good to excellent for kinematic variables and all ICCs were excellent; the SEM ranged from 0.60° to 1.99°. Conclusion Multi-segmented foot kinematics can be reliably measured in RA patients with pes planovalgus. Serial measurement of discrete variables for TP and other selected leg muscles via EMG is not supported from the findings in this cohort of RA patients. Caution should be exercised when EMG measurements are considered to study disease progression or intervention effects. PMID:22721819

E-cigarette Use and Willingness to Smoke in a Sample of Adolescent Nonsmokers

PubMed Central

Wills, Thomas A.; Sargent, James D.; Knight, Rebecca; Pagano, Ian; Gibbons, Frederick X.

2016-01-01

Objective There is little evidence on the consequences of electronic cigarette (e-cigarette) use in adolescence. With a multiethnic sample of nonsmokers, we assessed the relation between e-cigarette use and social-cognitive factors that predict smoking combustible cigarettes (cigarettes). Methods School-based cross-sectional survey of 2,309 high school students (M age 14.7 years). Participants reported on e-cigarette use and cigarette use; on smoking-related cognitions (smoking expectancies, prototypes of smokers) and peer smoker affiliations; and on willingness to smoke cigarettes. Regression analyses conducted for non-cigarette smokers tested the association between e-cigarette use and willingness to smoke cigarettes, controlling for demographics, parenting, academic and social competence, and personality variables. Structural equation modeling (SEM) analyses tested whether the relation between e-cigarette use and willingness was mediated through any of the three smoking-related variables. Results Nonsmokers who had used e-cigarettes (18% of the total sample) showed more willingness to smoke cigarettes compared to those who had never used any tobacco product; the adjusted odds ratio was 2.35 (95% confidence interval 1.73 – 3.19). Additionally, willingness prospectively predicted smoking onset. SEM showed that the relation between e-cigarette use and willingness to smoke was partly mediated through more positive expectancies about smoking but there was also a direct path from e-cigarette use to willingness. Conclusions Among adolescent nonsmokers, e-cigarette use is associated with willingness to smoke, a predictor of future cigarette smoking. The results suggest that use of e-cigarettes by adolescents is not without attitudinal risk for cigarette smoking. These findings have implications for formulation of policy about access to e-cigarettes by adolescents. PMID:26261237

Software analysis in the semantic web

NASA Astrophysics Data System (ADS)

Taylor, Joshua; Hall, Robert T.

2013-05-01

Many approaches in software analysis, particularly dynamic malware analyis, benefit greatly from the use of linked data and other Semantic Web technology. In this paper, we describe AIS, Inc.'s Semantic Extractor (SemEx) component from the Malware Analysis and Attribution through Genetic Information (MAAGI) effort, funded under DARPA's Cyber Genome program. The SemEx generates OWL-based semantic models of high and low level behaviors in malware samples from system call traces generated by AIS's introspective hypervisor, IntroVirtTM. Within MAAGI, these semantic models were used by modules that cluster malware samples by functionality, and construct "genealogical" malware lineages. Herein, we describe the design, implementation, and use of the SemEx, as well as the C2DB, an OWL ontology used for representing software behavior and cyber-environments.

The effect of SEM imaging on the Ar/Ar system in feldspars

NASA Astrophysics Data System (ADS)

Flude, S.; Sherlock, S.; Lee, M.; Kelley, S. P.

2010-12-01

Complex microtextures form in K-feldspar crystals as they cool and are affected by deuteric alteration. This complex structure is the cause of variable closure temperatures for Ar-Ar, a phenomenon which has been utilized in multi domain diffusion (MDD) modelling to recover thermal histories [1]. However, there has been substantial controversy regarding the precise interaction between feldspar microtextures and Ar-diffusion [2,3]. A number of studies have addressed this issue using coupled SEM imaging and Ar/Ar UV laser ablation microprobe (UV-LAMP) analysis on the same sample, to enable direct comparison of microtextures with Ar/Ar age data [4]. Here we have tested the idea that SEM work may affect Ar/Ar ages, leading to inaccurate results in subsequent Ar/Ar analyses. Three splits of alkali feldspar from the Dartmoor Granite in SW England were selected for Ar/Ar UV-LAMP analysis. Split 1 (“control”) was prepared as a polished thick section for Ar/Ar analysis. Split 2 (“SEM”) was prepared as a polished thick section, was chemically-mechanically polished with colloidal silica and underwent SEM imaging (uncoated) and focussed ion beam (FIB) milling (gold coated); electron beam damage in the SEM was maximised by leaving the sample at high magnification for eight minutes. Split 3 (“Etch”) is a cleavage fragment that was etched with HF vapour and underwent low to moderate magnification SEM imaging. The control split gave a range of laser-spot ages consistent with the expected cooling age of the granite and high yields of radiogenic 40Ar* (>90%). The area of the “SEM” split that experienced significant electron beam damage gave younger than expected ages and 40Ar* yields as low as 57%. These are interpreted as a combination of implantation of atmospheric Ar and local redistribution of K within the sample. The area of “SEM” that underwent FIB milling gave ages and 40Ar* yields comparable to the control split, suggesting that the Au-coat minimises FIB damage and that colloidal-polishing and low-magnification SEM imaging do not affect the Ar/Ar system. The “Etch” split gave younger than expected ages and 40Ar* yields as low as 58%, suggesting that HF etching also disrupts the Ar/Ar system. These results suggest that SEM techniques involving intense electron bombardment of an uncoated sample, such as charge contrast imaging and electron backscatter diffraction (EBSD), may disrupt the Ar/Ar system in the sample, leading to spurious results. Etching samples with HF, as is often done for routine Ar/Ar preparation of volcanic phenocrysts, introduces atmospheric Ar and may result in differential loss or gain of K and Ar isotopes, leading to spurious results. References [1] Lovera and Richter, 1989, J. Geophys. Res. 94, 17917-17935. [2] Parsons. et al., 1999, Cont. Min. Pet. 136, 92-110. [3] Mark et al., 2008, Geochim. Cosmochim. Acta, 72 2695-2710. [4] Reddy et al., 2001, Cont. Min. Pet., 141 186-200.

Land use influences arbuscular mycorrhizal fungal communities in the farming-pastoral ecotone of northern China.

PubMed

Xiang, Dan; Verbruggen, Erik; Hu, Yajun; Veresoglou, Stavros D; Rillig, Matthias C; Zhou, Wenping; Xu, Tianle; Li, Huan; Hao, Zhipeng; Chen, Yongliang; Chen, Baodong

2014-12-01

We performed a landscape-scale investigation to compare the arbuscular mycorrhizal fungal (AMF) communities between grasslands and farmlands in the farming-pastoral ecotone of northern China. AMF richness and community composition were examined with 454 pyrosequencing. Structural equation modelling (SEM) and multivariate analyses were applied to disentangle the direct and indirect effects (mediated by multiple environmental factors) of land use on AMF. Land use conversion from grassland to farmland significantly reduced AMF richness and extraradical hyphal length density, and these land use types also differed significantly in AMF community composition. SEM showed that the effects of land use on AMF richness and hyphal length density in soil were primarily mediated by available phosphorus and soil structural quality. Soil texture was the strongest predictor of AMF community composition. Soil carbon, nitrogen and soil pH were also significantly correlated with AMF community composition, indicating that these abiotic variables could be responsible for some of the community composition differences among sites. Our study shows that land use has a partly predictable effect on AMF communities across this ecologically relevant area of China, and indicates that high soil phosphorus concentrations and poor soil structure are particularly detrimental to AMF in this fragile ecosystem. © 2014 The Author. New Phytologist © 2014 New Phytologist Trust.

Affective temperaments play an important role in the relationship between childhood abuse and depressive symptoms in major depressive disorder.

PubMed

Toda, Hiroyuki; Inoue, Takeshi; Tsunoda, Tomoya; Nakai, Yukiei; Tanichi, Masaaki; Tanaka, Teppei; Hashimoto, Naoki; Takaesu, Yoshikazu; Nakagawa, Shin; Kitaichi, Yuji; Boku, Shuken; Tanabe, Hajime; Nibuya, Masashi; Yoshino, Aihide; Kusumi, Ichiro

2016-02-28

Previous studies have shown that various factors, such as genetic and environmental factors, contribute to the development of major depressive disorder (MDD). The aim of this study is to clarify how multiple factors, including affective temperaments, childhood abuse and adult life events, are involved in the severity of depressive symptoms in MDD. A total of 98 participants with MDD were studied using the following self-administered questionnaire surveys: Patient Health Questionnaire-9 measuring the severity of depressive symptoms; Life Experiences Survey (LES) measuring negative and positive adult life events; Temperament Evaluation of the Memphis, Pisa, Paris, and San Diego auto-questionnaire (TEMPS-A) measuring affective temperaments; and the Child Abuse and Trauma Scale (CATS) measuring childhood abuse. The data were analyzed using single and multiple regression analyses and structural equation modeling (SEM). The neglect score reported by CATS indirectly predicted the severity of depressive symptoms through affective temperaments measured by TEMPS-A in SEM. Four temperaments (depressive, cyclothymic, irritable, and anxious) directly predicted the severity of depressive symptoms. The negative change in the LES score also directly predicted severity. This study suggests that childhood abuse, especially neglect, indirectly increases the severity of depressive symptoms through increased scores of affective temperaments in MDD. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Direct and indirect relationships of physical fitness, weight status, and learning duration to academic performance in Japanese schoolchildren.

PubMed

Ishihara, Toru; Morita, Noriteru; Nakajima, Toshihiro; Okita, Koichi; Yamatsu, Koji; Sagawa, Masato

2018-03-01

The purpose of this study was to determine, using structural equation modelling (SEM), the direct and indirect influence of daily behaviours (i.e. exercise/learning durations), weight status, and physical fitness on academic performance among seventh-grade schoolchildren, after controlling for socioeconomic status. We analysed cross-sectional data from 274 schoolchildren (159 males and 115 females; 12-13 years old). Academic performance was assessed using the total grade points in eight academic subjects. Physical fitness was evaluated using the total score of eight physical fitness tests and weight status using body mass index. The daily behaviours and socioeconomic status were assessed by the questionnaire. The SEM showed an adequate fit to the data (χ 2  = 0.684, p = .710, RMSEA = .000). Physical fitness and learning durations had direct effects on academic performance (β = .301, p < .001; β = .132, p = .037, respectively) after controlling for confounders. Healthy weight status and exercise habits positively indirectly influenced academic performance via physical fitness. These findings suggest that, independent of socioeconomic status and learning durations, exercise habits and maintaining healthy weight status may indirectly contribute to academic success via better physical fitness in children.

In Situ Characterization of Boehmite Particles in Water Using Liquid SEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yao, Juan; Arey, Bruce W.; Yang, Li

In situ imaging and elemental analysis of boehmite (AlOOH) particles in water is realized using the System for Analysis at the Liquid Vacuum Interface (SALVI) and Scanning Electron Microscopy (SEM). This paper describes the method and key steps in integrating the vacuum compatible SAVLI to SEM and obtaining secondary electron (SE) images of particles in liquid in high vacuum. Energy dispersive x-ray spectroscopy (EDX) is used to obtain elemental analysis of particles in liquid. A synthesized AlOOH particle is used as a model in the liquid SEM illustration. Our results demonstrate that particles can be imaged in the SE modemore » with good resolution. The AlOOH EDX spectrum shows significant signal from the Al compared with deionized water and the empty channel control. In situ liquid SEM is a powerful technique to study particles in liquid with many exciting applications. This procedure aims to provide technical details in how to conduct liquid SEM imaging and EDX analysis using SALVI and reduce potential pitfalls using this approach for other researchers.« less

Fabrication of a silver particle-integrated silicone polymer-covered metal stent against sludge and biofilm formation and stent-induced tissue inflammation

PubMed Central

Lee, Tae Hoon; Jang, Bong Seok; Jung, Min Kyo; Pack, Chan Gi; Choi, Jun-Ho; Park, Do Hyun

2016-01-01

To reduce tissue or tumor ingrowth, covered self-expandable metal stents (SEMSs) have been developed. The effectiveness of covered SEMSs may be attenuated by sludge or stone formation or by stent clogging due to the formation of biofilm on the covering membrane. In this study, we tested the hypothesis that a silicone membrane containing silver particles (Ag-P) would prevent sludge and biofilm formation on the covered SEMS. In vitro, the Ag-P-integrated silicone polymer-covered membrane exhibited sustained antibacterial activity, and there was no definite release of silver ions from the Ag-P-integrated silicone polymer membrane at any time point. Using a porcine stent model, in vivo analysis demonstrated that the Ag-P-integrated silicone polymer-covered SEMS reduced the thickness of the biofilm and the quantity of sludge formed, compared with a conventional silicone-covered SEMS. In vivo, the release of silver ions from an Ag-P-integrated silicone polymer-covered SEMS was not detected in porcine serum. The Ag-P-integrated silicone polymer-covered SEMS also resulted in significantly less stent-related bile duct and subepithelium tissue inflammation than a conventional silicone polymer-covered SEMS. Therefore, the Ag-P-integrated silicone polymer-covered SEMS reduced sludge and biofilm formation and stent-induced pathological changes in tissue. This novel SEMS may prolong the stent patency in clinical application. PMID:27739486

Focused ion beam (FIB)/scanning electron microscopy (SEM) in tissue structural research.

PubMed

Leser, Vladka; Milani, Marziale; Tatti, Francesco; Tkalec, Ziva Pipan; Strus, Jasna; Drobne, Damjana

2010-10-01

The focused ion beam (FIB) and scanning electron microscope (SEM) are commonly used in material sciences for imaging and analysis of materials. Over the last decade, the combined FIB/SEM system has proven to be also applicable in the life sciences. We have examined the potential of the focused ion beam/scanning electron microscope system for the investigation of biological tissues of the model organism Porcellio scaber (Crustacea: Isopoda). Tissue from digestive glands was prepared as for conventional SEM or as for transmission electron microscopy (TEM). The samples were transferred into FIB/SEM for FIB milling and an imaging operation. FIB-milled regions were secondary electron imaged, back-scattered electron imaged, or energy dispersive X-ray (EDX) analyzed. Our results demonstrated that FIB/SEM enables simultaneous investigation of sample gross morphology, cell surface characteristics, and subsurface structures. The same FIB-exposed regions were analyzed by EDX to provide basic compositional data. When samples were prepared as for TEM, the information obtained with FIB/SEM is comparable, though at limited magnification, to that obtained from TEM. A combination of imaging, micro-manipulation, and compositional analysis appears of particular interest in the investigation of epithelial tissues, which are subjected to various endogenous and exogenous conditions affecting their structure and function. The FIB/SEM is a promising tool for an overall examination of epithelial tissue under normal, stressed, or pathological conditions.

Fabrication of a silver particle-integrated silicone polymer-covered metal stent against sludge and biofilm formation and stent-induced tissue inflammation.

PubMed

Lee, Tae Hoon; Jang, Bong Seok; Jung, Min Kyo; Pack, Chan Gi; Choi, Jun-Ho; Park, Do Hyun

2016-10-14

To reduce tissue or tumor ingrowth, covered self-expandable metal stents (SEMSs) have been developed. The effectiveness of covered SEMSs may be attenuated by sludge or stone formation or by stent clogging due to the formation of biofilm on the covering membrane. In this study, we tested the hypothesis that a silicone membrane containing silver particles (Ag-P) would prevent sludge and biofilm formation on the covered SEMS. In vitro, the Ag-P-integrated silicone polymer-covered membrane exhibited sustained antibacterial activity, and there was no definite release of silver ions from the Ag-P-integrated silicone polymer membrane at any time point. Using a porcine stent model, in vivo analysis demonstrated that the Ag-P-integrated silicone polymer-covered SEMS reduced the thickness of the biofilm and the quantity of sludge formed, compared with a conventional silicone-covered SEMS. In vivo, the release of silver ions from an Ag-P-integrated silicone polymer-covered SEMS was not detected in porcine serum. The Ag-P-integrated silicone polymer-covered SEMS also resulted in significantly less stent-related bile duct and subepithelium tissue inflammation than a conventional silicone polymer-covered SEMS. Therefore, the Ag-P-integrated silicone polymer-covered SEMS reduced sludge and biofilm formation and stent-induced pathological changes in tissue. This novel SEMS may prolong the stent patency in clinical application.

Massive metrology using fast e-beam technology improves OPC model accuracy by >2x at faster turnaround time

NASA Astrophysics Data System (ADS)

Zhao, Qian; Wang, Lei; Wang, Jazer; Wang, ChangAn; Shi, Hong-Fei; Guerrero, James; Feng, Mu; Zhang, Qiang; Liang, Jiao; Guo, Yunbo; Zhang, Chen; Wallow, Tom; Rio, David; Wang, Lester; Wang, Alvin; Wang, Jen-Shiang; Gronlund, Keith; Lang, Jun; Koh, Kar Kit; Zhang, Dong Qing; Zhang, Hongxin; Krishnamurthy, Subramanian; Fei, Ray; Lin, Chiawen; Fang, Wei; Wang, Fei

2018-03-01

Classical SEM metrology, CD-SEM, uses low data rate and extensive frame-averaging technique to achieve high-quality SEM imaging for high-precision metrology. The drawbacks include prolonged data collection time and larger photoresist shrinkage due to excess electron dosage. This paper will introduce a novel e-beam metrology system based on a high data rate, large probe current, and ultra-low noise electron optics design. At the same level of metrology precision, this high speed e-beam metrology system could significantly shorten data collection time and reduce electron dosage. In this work, the data collection speed is higher than 7,000 images per hr. Moreover, a novel large field of view (LFOV) capability at high resolution was enabled by an advanced electron deflection system design. The area coverage by LFOV is >100x larger than classical SEM. Superior metrology precision throughout the whole image has been achieved, and high quality metrology data could be extracted from full field. This new capability on metrology will further improve metrology data collection speed to support the need for large volume of metrology data from OPC model calibration of next generation technology. The shrinking EPE (Edge Placement Error) budget places more stringent requirement on OPC model accuracy, which is increasingly limited by metrology errors. In the current practice of metrology data collection and data processing to model calibration flow, CD-SEM throughput becomes a bottleneck that limits the amount of metrology measurements available for OPC model calibration, impacting pattern coverage and model accuracy especially for 2D pattern prediction. To address the trade-off in metrology sampling and model accuracy constrained by the cycle time requirement, this paper employs the high speed e-beam metrology system and a new computational software solution to take full advantage of the large volume data and significantly reduce both systematic and random metrology errors. The new computational software enables users to generate large quantity of highly accurate EP (Edge Placement) gauges and significantly improve design pattern coverage with up to 5X gain in model prediction accuracy on complex 2D patterns. Overall, this work showed >2x improvement in OPC model accuracy at a faster model turn-around time.

Path analysis of the chronicity of depression using the comprehensive developmental model framework.

PubMed

Fandiño-Losada, Andrés; Bangdiwala, Shrikant I; Lavebratt, Catharina; Forsell, Yvonne

2016-07-01

Background Depressive disorder is recognized as recurrent or chronic in the majority of affected individuals; but literature is not consistent about determinants of the disorder course. Aims To analyse the relationships between familial, personal and environmental characteristics in different life phases and their effects on the chronicity of depression in a population-based sample. Methods It was a longitudinal panel study with three waves (W1-W3) for 651 adult men and women with diagnosis of minor/major depression or dysthymia at W1 of the Swedish PART (mental health, work and relations) study. Risk factors and co-morbidities were assessed with questionnaires. The main outcome was an episode of minor/major depression or dysthymia at 10-12 years of follow-up (W3). Liability for depressive episodes was determined using exploratory structural equation modelling (SEM), following a path approach with step-wise specification searches. Results Most of the risk factors determined, directly or indirectly, depression severity at W3. Somatic trait anxiety, partner loss and other negative life events at W1, depressive symptoms at W2, and life difficulties and other dependent life events at W3 had direct effects on the outcome. Conclusions SEM model revealed complex and intertwined psychopathological pathways leading to chronicity of depression, given previous episodes, which could be assembled in two main mechanisms: a depressive-internalizing path and an adversity path comprised of life events. Pathways are simpler than those of depression occurrence, emphasizing the relevance of personality factors as depression determinants, and excluding disability levels, co-morbidities and social support. These novel findings need to be replicated in future studies.

Repeatability of a 3D multi-segment foot model during anterior and lateral step down tests.

PubMed

Lucareli, Paulo Roberto Garcia; Contani, Luciane Beatriz Grohs; Lima, Bruna; Rabelo, Nayra Deise dos Anjos; Ferreira, Cintia Lopes; Lima, Fernanda Pulpio Silva; Correa, João Carlos Ferrari; Politti, Fabiano

2016-01-01

The aim of the present study was to analyse the reproducibility of the Oxford Foot Model (OFM) when used with healthy adults during two clinical tests, i.e., the Anterior Step Down Test (SDA) and the Lateral Step Down Test (SDL). Five healthy participants (one male and four females, 10 limbs in total) with a mean age of 22.2 (19-30) years were assessed in four sessions of tests conducted at intervals of one week. Two independent examiners performed two of the sessions of each of the tests. For each session (intra-day), nine repetitions of each clinical test (SDA and SDL) were performed. After an interval of three hours, the data were collected again. The tests were conducted again after an interval of one week using the same experimental conditions. The intra- and inter-session repeatabilities of the ranges of motion of the feet were determined according to the standard error of measurement (SEM) for each examiner and for the differences between the examiners. The repeatabilities of the results were high for both of the conducted tests. The SEM results were as follows: 0.47-1.94° for the intra-examiner assessment (SDA), 0.55-2.01° for the inter-examiner comparison (SDA), 0.44-2.43° for the intra-examiner assessment (SDL), and 0.54-1.89° for the inter-examiner comparison (SDL). The OFM model was shown to be reproducible in terms of assessing the range of motion of healthy adults during functional tests (SDA and SDL). Copyright © 2015 Elsevier B.V. All rights reserved.

Fall Risk, Supports and Services, and Falls Following a Nursing Home Discharge.

PubMed

Noureldin, Marwa; Hass, Zachary; Abrahamson, Kathleen; Arling, Greg

2017-09-04

Falls are a major source of morbidity and mortality among older adults; however, little is known regarding fall occurrence during a nursing home (NH) to community transition. This study sought to examine whether the presence of supports and services impacts the relationship between fall-related risk factors and fall occurrence post NH discharge. Participants in the Minnesota Return to Community Initiative who were assisted in achieving a community discharge (N = 1459) comprised the study sample. The main outcome was fall occurrence within 30 days of discharge. Factor analyses were used to estimate latent models from variables of interest. A structural equation model (SEM) was estimated to determine the relationship between the emerging latent variables and falls. Fifteen percent of participants fell within 30 days of NH discharge. Factor analysis of fall-related risk factors produced three latent variables: fall concerns/history; activities of daily living impairments; and use of high-risk medications. A supports/services latent variable also emerged that included caregiver support frequency, medication management assistance, durable medical equipment use, discharge location, and receipt of home health or skilled nursing services. In the SEM model, high-risk medications use and fall concerns/history had direct positive effects on falling. Receiving supports/services did not affect falling directly; however, it reduced the effect of high-risk medication use on falling (p < .05). Within the context of a state-implemented transition program, findings highlight the importance of supports/services in mitigating against medication-related risk of falling post NH discharge. © The Author 2017. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Psychiatric disability as mediator of the neurocognition-functioning link in schizophrenia spectrum disorders: SEM analysis using the Evaluation of Cognitive Processes involved in Disability in Schizophrenia (ECPDS) scale.

PubMed

Roux, Paul; Urbach, Mathieu; Fonteneau, Sandrine; Berna, Fabrice; Brunel, Lore; Capdevielle, Delphine; Chereau, Isabelle; Dubreucq, Julien; Faget-Agius, Catherine; Fond, Guillaume; Leignier, Sylvain; Perier, Claire-Cécile; Richieri, Raphaëlle; Schneider, Priscille; Schürhoff, Franck; Tronche, Anne-Marie; Yazbek, Hanan; Zinetti-Bertschy, Anna; Passerieux, Christine; Brunet-Gouet, Eric

2018-06-22

The functional outcome in schizophrenia spectrum disorders is affected by multiple factors such as cognitive performance and clinical symptoms. Psychiatric disability may be another important determinant of functional outcome. The purpose of this study was to test whether schizophrenia symptoms and psychiatric disability mediated the association between cognition and functioning. Between April 2013 and July 2017, we included 108 community-dwelling adults with stable schizophrenia spectrum disorder in a multicenter study. Psychiatric disability was assessed with the Evaluation of Cognitive Processes involved in Disability in Schizophrenia (ECPDS) scale by relatives of patients. ECPDS focused on the broad array of motivational, neurocognitive, sociocognitive, and metacognitive impairments that result in activity restrictions. We used a battery of tests to assess seven cognition domains (processing speed, attention/vigilance, working, verbal and visual memory, reasoning and problem solving, and executive functioning) and cross-sectional structural equation modeling (SEM) for the mediation analyses. We estimated the one-year temporal stability of ECPDS scores in 45 participants. The model provided showed good fit and explained 43.9% of the variance in functioning. The effect of neurocognition on functioning was fully mediated by symptoms (proportion mediated: 36.5%) and psychiatric disability (proportion mediated: 31.3%). The ECPDS score had acceptable one-year temporal stability. The ECPDS scale has satisfactory psychometric properties, and shows significant convergence with neurocognition and functioning, suggesting a role for this tool in the routine evaluation of cognitive remediation needs. Our model validates psychiatric disability as a crucial step from cognitive impairment to restricted participation in life situations. Copyright © 2018 Elsevier B.V. All rights reserved.

Effective connectivity of visual word recognition and homophone orthographic errors

PubMed Central

Guàrdia-Olmos, Joan; Peró-Cebollero, Maribel; Zarabozo-Hurtado, Daniel; González-Garrido, Andrés A.; Gudayol-Ferré, Esteve

2015-01-01

The study of orthographic errors in a transparent language like Spanish is an important topic in relation to writing acquisition. The development of neuroimaging techniques, particularly functional magnetic resonance imaging (fMRI), has enabled the study of such relationships between brain areas. The main objective of the present study was to explore the patterns of effective connectivity by processing pseudohomophone orthographic errors among subjects with high and low spelling skills. Two groups of 12 Mexican subjects each, matched by age, were formed based on their results in a series of ad hoc spelling-related out-scanner tests: a high spelling skills (HSSs) group and a low spelling skills (LSSs) group. During the f MRI session, two experimental tasks were applied (spelling recognition task and visuoperceptual recognition task). Regions of Interest and their signal values were obtained for both tasks. Based on these values, structural equation models (SEMs) were obtained for each group of spelling competence (HSS and LSS) and task through maximum likelihood estimation, and the model with the best fit was chosen in each case. Likewise, dynamic causal models (DCMs) were estimated for all the conditions across tasks and groups. The HSS group’s SEM results suggest that, in the spelling recognition task, the right middle temporal gyrus, and, to a lesser extent, the left parahippocampal gyrus receive most of the significant effects, whereas the DCM results in the visuoperceptual recognition task show less complex effects, but still congruent with the previous results, with an important role in several areas. In general, these results are consistent with the major findings in partial studies about linguistic activities but they are the first analyses of statistical effective brain connectivity in transparent languages. PMID:26042070

Topsoil structure stability in a restored floodplain: Impacts of fluctuating water levels, soil parameters and ecosystem engineers.

PubMed

Schomburg, A; Schilling, O S; Guenat, C; Schirmer, M; Le Bayon, R C; Brunner, P

2018-10-15

Ecosystem services provided by floodplains are strongly controlled by the structural stability of soils. The development of a stable structure in floodplain soils is affected by a complex and poorly understood interplay of hydrological, physico-chemical and biological processes. This paper aims at analysing relations between fluctuating groundwater levels, soil physico-chemical and biological parameters on soil structure stability in a restored floodplain. Water level fluctuations in the soil are modelled using a numerical surface-water-groundwater flow model and correlated to soil physico-chemical parameters and abundances of plants and earthworms. Causal relations and multiple interactions between the investigated parameters are tested through structural equation modelling (SEM). Fluctuating water levels in the soil did not directly affect the topsoil structure stability, but indirectly through affecting plant roots and soil parameters that in turn determine topsoil structure stability. These relations remain significant for mean annual days of complete and partial (>25%) water saturation. Ecosystem functioning of a restored floodplain might already be affected by the fluctuation of groundwater levels alone, and not only through complete flooding by surface water during a flood period. Surprisingly, abundances of earthworms did not show any relation to other variables in the SEM. These findings emphasise that earthworms have efficiently adapted to periodic stress and harsh environmental conditions. Variability of the topsoil structure stability is thus stronger driven by the influence of fluctuating water levels on plants than by the abundance of earthworms. This knowledge about the functional network of soil engineering organisms, soil parameters and fluctuating water levels and how they affect soil structural stability is of fundamental importance to define management strategies of near-natural or restored floodplains in the future. Copyright © 2018 Elsevier B.V. All rights reserved.

Measurement invariance via multigroup SEM: Issues and solutions with chi-square-difference tests.

PubMed

Yuan, Ke-Hai; Chan, Wai

2016-09-01

Multigroup structural equation modeling (SEM) plays a key role in studying measurement invariance and in group comparison. When population covariance matrices are deemed not equal across groups, the next step to substantiate measurement invariance is to see whether the sample covariance matrices in all the groups can be adequately fitted by the same factor model, called configural invariance. After configural invariance is established, cross-group equalities of factor loadings, error variances, and factor variances-covariances are then examined in sequence. With mean structures, cross-group equalities of intercepts and factor means are also examined. The established rule is that if the statistic at the current model is not significant at the level of .05, one then moves on to testing the next more restricted model using a chi-square-difference statistic. This article argues that such an established rule is unable to control either Type I or Type II errors. Analysis, an example, and Monte Carlo results show why and how chi-square-difference tests are easily misused. The fundamental issue is that chi-square-difference tests are developed under the assumption that the base model is sufficiently close to the population, and a nonsignificant chi-square statistic tells little about how good the model is. To overcome this issue, this article further proposes that null hypothesis testing in multigroup SEM be replaced by equivalence testing, which allows researchers to effectively control the size of misspecification before moving on to testing a more restricted model. R code is also provided to facilitate the applications of equivalence testing for multigroup SEM. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Chemical modification of magnetite nanoparticles and preparation of acrylic-base magnetic nanocomposite particles via miniemulsion polymerization

NASA Astrophysics Data System (ADS)

Mahdieh, Athar; Mahdavian, Ali Reza; Salehi-Mobarakeh, Hamid

2017-03-01

Nowadays, magnetic nanocomposite particles have attracted many interests because of their versatile applications. A new method for chemical modification of Fe3O4 nanoparticles with polymerizable groups is presented here. After synthesis of Fe3O4 nanoparticles by co-precipitation method, they were modified sequentially with 3-aminopropyl triethoxysilane (APTES), acryloyl chloride (AC) and benzoyl chloride (BC) and all were characterized by FTIR, XRD, SEM and TGA analyses. Then the modified magnetite nanoparticles with unsaturated acrylic groups were copolymerized with methyl methacrylate (MMA), butyl acrylate (BA) and acrylic acid (AA) through miniemulsion polymerization. Although several reports exist on preparation of magnetite-base polymer particles, but the efficiency of magnetite encapsulationwith reasonable content and obtaining final stable latexes with limited aggregation ofFe3O4 are still important issues. These were considered here by controlling reaction parameters. Hence, a seriesofmagneticnanocomposites latex particlescontaining different amounts of Fe3O4 nanoparticles (0-10 wt%) were prepared with core-shell morphology and diameter below 200 nm and were characterized by FT-IR, DSC and TGA analyses. Their morphology and size distribution were studied by SEM, TEM and DLS analyses too. Magnetic properties of all products were also measuredby VSM analysis and the results revealed almost superparamagnetic properties for the obtained nanocomposite particles.

Longitudinal patterns of semantic and episodic memory in frontotemporal lobar degeneration and Alzheimer's disease.

PubMed

Xie, Sharon X; Libon, David J; Wang, Xingmei; Massimo, Lauren; Moore, Peachie; Vesely, Luisa; Khan, Alea; Chatterjee, Anjan; Coslett, H Branch; Hurtig, Howard I; Liang, Tsao-Wei; Grossman, Murray

2010-03-01

The longitudinal assessment of episodic and semantic memory was obtained from 236 patients diagnosed with Alzheimer's disease (AD, n = 128) and with frontotemporal lobar degeneration (FTLD, n = 108), including patients with a social comportment/dysexecutive (SOC/EXEC) disorder, progressive nonfluent aphasia (PNFA), semantic dementia (SemD), and corticobasal syndrome (CBS). At the initial assessment, AD patients obtained a lower score on the delayed free recall test than other patients. Longitudinal analyses for delayed free recall found converging performance, with all patients reaching the same level of impairment as AD patients. On the initial evaluation for delayed recognition, AD patients also obtained lower scores than other groups. Longitudinal analyses for delayed recognition test performance found that AD patients consistently produced lower scores than other groups and no convergence between AD and other dementia groups was seen. For semantic memory, there were no initial between-group differences. However, longitudinal analyses for semantic memory revealed group differences over illness duration, with worse performance for SemD versus AD, PNFA, SOC/EXEC, and CBS patients. These data suggest the presence of specific longitudinal patterns of impairment for episodic and semantic memory in AD and FTLD patients suggesting that all forms of dementia do not necessarily converge into a single phenotype.

The Feasibility of Using Causal Indicators in Educational Measurement

ERIC Educational Resources Information Center

Wang, Jue; Engelhard, George, Jr.

2016-01-01

The authors of the focus article describe an important issue related to the use and interpretation of causal indicators within the context of structural equation modeling (SEM). In the focus article, the authors illustrate with simulated data the effects of omitting a causal indicator. Since SEMs are used extensively in the social and behavioral…

Improving access in gastroenterology: The single point of entry model for referrals

PubMed Central

Novak, Kerri L; Van Zanten, Sander Veldhuyzen; Pendharkar, Sachin R

2013-01-01

In 2005, a group of academic gastroenterologists in Calgary (Alberta) adopted a centralized referral intake system known as central triage. This system provided a single point of entry model (SEM) for referrals rather than the traditional system of individual practitioners managing their own referrals and queues. The goal of central triage was to improve wait times and referral management. In 2008, a similar system was developed in Edmonton at the University of Alberta Hospital (Edmonton, Alberta). SEMs have subsequently been adopted by numerous subspecialties throughout Alberta. There are many benefits of SEMs including improved access and reduced wait times. Understanding and measuring complex patient flow systems is key to improving access, and centralized intake systems provide an opportunity to better understand total demand and system bottlenecks. This knowledge is particularly important for specialties such as gastroenterology (GI), in which demand exceeds supply. While it is anticipated that SEMs will reduce wait times for GI care in Canada, the lack of sufficient resources to meet the demand for GI care necessitates additional strategies. PMID:24040629

Improving access in gastroenterology: the single point of entry model for referrals.

PubMed

Novak, Kerri; Veldhuyzen Van Zanten, Sander; Pendharkar, Sachin R

2013-11-01

In 2005, a group of academic gastroenterologists in Calgary (Alberta) adopted a centralized referral intake system known as central triage. This system provided a single point of entry model (SEM) for referrals rather than the traditional system of individual practitioners managing their own referrals and queues. The goal of central triage was to improve wait times and referral management. In 2008, a similar system was developed in Edmonton at the University of Alberta Hospital (Edmonton, Alberta). SEMs have subsequently been adopted by numerous subspecialties throughout Alberta. There are many benefits of SEMs including improved access and reduced wait times. Understanding and measuring complex patient flow systems is key to improving access, and centralized intake systems provide an opportunity to better understand total demand and system bottlenecks. This knowledge is particularly important for specialties such as gastroenterology (GI), in which demand exceeds supply. While it is anticipated that SEMs will reduce wait times for GI care in Canada, the lack of sufficient resources to meet the demand for GI care necessitates additional strategies.

Using a Structural Equation Modelling Approach (SEM) to Examine Leadership of Heads of Subject Departments (HODs) as Perceived by Principals and Vice-Principals, Heads of Subject Departments and Teachers within "School Based Management" (SBM) Secondary Schools: Some Evidence from Hong Kong

ERIC Educational Resources Information Center

Au, Loretta; Wright, Nigel; Botton, Christopher

2003-01-01

This article reports the use of a Structural Equation Modelling (SEM) technique as a means of exploring our understanding of the leadership of Heads of Subject Departments within School Based Management (SBM) secondary schools in Hong Kong. Arguments made by Gronn (1999, 2000), Spillane et al. (2001) suggest that studies of leadership need to…

A structural equation modeling approach for the adoption of cloud computing to enhance the Malaysian healthcare sector.

PubMed

Ratnam, Kalai Anand; Dominic, P D D; Ramayah, T

2014-08-01

The investments and costs of infrastructure, communication, medical-related equipments, and software within the global healthcare ecosystem portray a rather significant increase. The emergence of this proliferation is then expected to grow. As a result, information and cross-system communication became challenging due to the detached independent systems and subsystems which are not connected. The overall model fit expending over a sample size of 320 were tested with structural equation modelling (SEM) using AMOS 20.0 as the modelling tool. SPSS 20.0 is used to analyse the descriptive statistics and dimension reliability. Results of the study show that system utilisation and system impact dimension influences the overall level of services of the healthcare providers. In addition to that, the findings also suggest that systems integration and security plays a pivotal role for IT resources in healthcare organisations. Through this study, a basis for investigation on the need to improvise the Malaysian healthcare ecosystem and the introduction of a cloud computing platform to host the national healthcare information exchange has been successfully established.

Access to primary care for socio-economically disadvantaged older people in rural areas: exploring realist theory using structural equation modelling in a linked dataset.

PubMed

Ford, John A; Jones, Andy; Wong, Geoff; Clark, Allan; Porter, Tom; Steel, Nick

2018-06-19

Realist approaches seek to answer questions such as 'how?', 'why?', 'for whom?', 'in what circumstances?' and 'to what extent?' interventions 'work' using context-mechanism-outcome (CMO) configurations. Quantitative methods are not well-established in realist approaches, but structural equation modelling (SEM) may be useful to explore CMO configurations. Our aim was to assess the feasibility and appropriateness of SEM to explore CMO configurations and, if appropriate, make recommendations based on our access to primary care research. Our specific objectives were to map variables from two large population datasets to CMO configurations from our realist review looking at access to primary care, generate latent variables where needed, and use SEM to quantitatively test the CMO configurations. A linked dataset was created by merging individual patient data from the English Longitudinal Study of Ageing and practice data from the GP Patient Survey. Patients registered in rural practices and who were in the highest deprivation tertile were included. Three latent variables were defined using confirmatory factor analysis. SEM was used to explore the nine full CMOs. All models were estimated using robust maximum likelihoods and accounted for clustering at practice level. Ordinal variables were treated as continuous to ensure convergence. We successfully explored our CMO configurations, but analysis was limited because of data availability. Two hundred seventy-six participants were included. We found a statistically significant direct (context to outcome) or indirect effect (context to outcome via mechanism) for two of nine CMOs. The strongest association was between 'ease of getting through to the surgery' and 'being able to get an appointment' with an indirect mediated effect through convenience (proportion of the indirect effect of the total was 21%). Healthcare experience was not directly associated with getting an appointment, but there was a statistically significant indirect effect through convenience (53% mediated effect). Model fit indices showed adequate fit. SEM allowed quantification of CMO configurations and could complement other qualitative and quantitative techniques in realist evaluations to support inferences about strengths of relationships. Future research exploring CMO configurations with SEM should aim to collect, preferably continuous, primary data.

Physicochemical characterization of Capstone depleted uranium aerosols III: morphologic and chemical oxide analyses.

PubMed

Krupka, Kenneth M; Parkhurst, Mary Ann; Gold, Kenneth; Arey, Bruce W; Jenson, Evan D; Guilmette, Raymond A

2009-03-01

The impact of depleted uranium (DU) penetrators against an armored target causes erosion and fragmentation of the penetrators, the extent of which is dependent on the thickness and material composition of the target. Vigorous oxidation of the DU particles and fragments creates an aerosol of DU oxide particles and DU particle agglomerations combined with target materials. Aerosols from the Capstone DU aerosol study, in which vehicles were perforated by DU penetrators, were evaluated for their oxidation states using x-ray diffraction (XRD), and particle morphologies were examined using scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS). The oxidation state of a DU aerosol is important as it offers a clue to its solubility in lung fluids. The XRD analysis showed that the aerosols evaluated were a combination primarily of U3O8 (insoluble) and UO3 (relatively more soluble) phases, though intermediate phases resembling U4O9 and other oxides were prominent in some samples. Analysis of particle residues in the micrometer-size range by SEM/EDS provided microstructural information such as phase composition and distribution, fracture morphology, size distribution, and material homogeneity. Observations from SEM analysis show a wide variability in the shapes of the DU particles. Some of the larger particles were spherical, occasionally with dendritic or lobed surface structures. Others appear to have fractures that perhaps resulted from abrasion and comminution, or shear bands that developed from plastic deformation of the DU material. Amorphous conglomerates containing metals other than uranium were also common, especially with the smallest particle sizes. A few samples seemed to contain small bits of nearly pure uranium metal, which were verified by EDS to have a higher uranium content exceeding that expected for uranium oxides. Results of the XRD and SEM/EDS analyses were used in other studies described in this issue of Health Physics to interpret the results of lung solubility studies and in selecting input parameters for dose assessments.

Glycaemic index of different coconut (Cocos nucifera)-flour products in normal and diabetic subjects.

PubMed

Trinidad, Trinidad P; Valdez, Divinagracia H; Loyola, Anacleta S; Mallillin, Aida C; Askali, Faridah C; Castillo, Joan C; Masa, Dina B

2003-09-01

The glycaemic index (GI) of commonly consumed bakery products supplemented with increasing levels of coconut (Cocos nucifera) flour was determined in ten normal and ten diabetic subjects. Using a randomized crossover design, the control and test foods were fed in random order on separate occasions after an overnight fast. Blood samples were collected through finger prick before and after feeding and were analysed for glucose levels using a clinical chemistry analyser. The significantly low-GI (<60) foods investigated were: macaroons (GI 45.7 (sem 3.0)) and carrot cake (GI 51.8 (sem 3.3)), with 200-250 g coconut flour/kg (P<0.05). The test foods with 150 g coconut flour/kg had GI ranging from 61.3 to 71.4. Among the test foods, pan de sal (GI 87.2 (sem 5.5)) and multigrain loaf (GI 85.2 (sem 6.8)) gave significantly higher GI with 50 and 100 g coconut flour/kg respectively (P<0.05). On the other hand, granola bar and cinnamon bread with 50 and 100 g coconut flour/kg respectively gave a GI ranging from 62.7 to 71.6 and did not differ significantly from the test foods with 150 g coconut flour/kg (P<0.05). A very strong negative correlation (r -0.85, n 11, P<0.005) was observed between the GI and dietary fibre content of the test foods supplemented with coconut flour. In conclusion, the GI of coconut flour-supplemented foods decreased with increasing levels of coconut flour and this may be due to its high dietary fibre content. The results of the present study may form a scientific basis for the development of coconut flour as a functional food. However, the fat content of coconut flour-supplemented food should always be considered to optimize the functionality of coconut fibre in the proper control and management of diabetes mellitus.

Physicochemical Characterization of Capstone Depleted Uranium Aerosols III: Morphologic and Chemical Oxide Analyses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krupka, Kenneth M.; Parkhurst, MaryAnn; Gold, Kenneth

2009-03-01

The impact of depleted uranium (DU) penetrators against an armored target causes erosion and fragmentation of the penetrators, the extent of which is dependent on the thickness and material composition of the target. Vigorous oxidation of the DU particles and fragments creates an aerosol of DU oxide particles and DU particle agglomerations combined with target materials. Aerosols from the Capstone DU aerosol study, in which vehicles were perforated by DU penetrators, were evaluated for their oxidation states using X-ray diffraction (XRD) and particle morphologies using scanning electron microscopy/energy dispersive spectrometry (SEM/EDS). The oxidation state of a DU aerosol is importantmore » as it offers a clue to its solubility in lung fluids. The XRD analysis showed that the aerosols evaluated were a combination primarily of U3O8 (insoluble) and UO3 (relatively more soluble) phases, though intermediate phases resembling U4O9 and other oxides were prominent in some samples. Analysis of particle residues in the micrometer-size range by SEM/EDS provided microstructural information such as phase composition and distribution, fracture morphology, size distribution, and material homogeneity. Observations from SEM analysis show a wide variability in the shapes of the DU particles. Some of the larger particles appear to have been fractured (perhaps as a result of abrasion and comminution); others were spherical, occasionally with dendritic or lobed surface structures. Amorphous conglomerates containing metals other than uranium were also common, especially with the smallest particle sizes. A few samples seemed to contain small chunks of nearly pure uranium metal, which were verified by EDS to have a higher uranium content exceeding that expected for uranium oxides. Results of the XRD and SEM/EDS analyses were used in other studies described in this issue of The Journal of Health Physics to interpret the results of lung solubility studies and in selecting input parameters for dose assessments.« less

Measurement properties of the WOMAC LK 3.1 pain scale.

PubMed

Stratford, P W; Kennedy, D M; Woodhouse, L J; Spadoni, G F

2007-03-01

The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) is applied extensively to patients with osteoarthritis of the hip or knee. Previous work has challenged the validity of its physical function scale however an extensive evaluation of its pain scale has not been reported. Our purpose was to estimate internal consistency, factorial validity, test-retest reliability, and the standard error of measurement (SEM) of the WOMAC LK 3.1 pain scale. Four hundred and seventy-four patients with osteoarthritis of the hip or knee awaiting arthroplasty were administered the WOMAC. Estimates of internal consistency (coefficient alpha), factorial validity (confirmatory factor analysis), and the SEM based on internal consistency (SEM(IC)) were obtained. Test-retest reliability [Type 2,1 intraclass correlation coefficients (ICC)] and a corresponding SEM(TRT) were estimated on a subsample of 36 patients. Our estimates were: internal consistency alpha=0.84; SEM(IC)=1.48; Type 2,1 ICC=0.77; SEM(TRT)=1.69. Confirmatory factor analysis failed to support a single factor structure of the pain scale with uncorrelated error terms. Two comparable models provided excellent fit: (1) a model with correlated error terms between the walking and stairs items, and between night and sit items (chi2=0.18, P=0.98); (2) a two factor model with walking and stairs items loading on one factor, night and sit items loading on a second factor, and the standing item loading on both factors (chi2=0.18, P=0.98). Our examination of the factorial structure of the WOMAC pain scale failed to support a single factor and internal consistency analysis yielded a coefficient less than optimal for individual patient use. An alternate strategy to summing the five-item responses when considering individual patient application would be to interpret item responses separately or to sum only those items which display homogeneity.

Dynamic predictive model for growth of Salmonella spp. in scrambled egg mix.

PubMed

Li, Lin; Cepeda, Jihan; Subbiah, Jeyamkondan; Froning, Glenn; Juneja, Vijay K; Thippareddi, Harshavardhan

2017-06-01

Liquid egg products can be contaminated with Salmonella spp. during processing. A dynamic model for the growth of Salmonella spp. in scrambled egg mix - high solids (SEM) was developed and validated. SEM was prepared and inoculated with ca. 2 log CFU/mL of a five serovar Salmonella spp. cocktail. Salmonella spp. growth data at isothermal temperatures (10, 15, 20, 25, 30, 35, 37, 39, 41, 43, 45, and 47 °C) in SEM were collected. Baranyi model was used (primary model) to fit growth data and the maximum growth rate and lag phase duration for each temperature were determined. A secondary model was developed with maximum growth rate as a function of temperature. The model performance measures, root mean squared error (RMSE, 0.09) and pseudo-R 2 (1.00) indicated good fit for both primary and secondary models. A dynamic model was developed by integrating the primary and secondary models and validated using two sinusoidal temperature profiles, 5-15 °C (low temperature) for 480 h and 10-40 °C (high temperature) for 48 h. The RMSE values for the sinusoidal low and high temperature profiles were 0.47 and 0.42 log CFU/mL, respectively. The model can be used to predict Salmonella spp. growth in case of temperature abuse during liquid egg processing. Copyright © 2016. Published by Elsevier Ltd.

Assessment of biofilm changes and concentration-depth profiles during arsenopyrite oxidation by Acidithiobacillus thiooxidans.

PubMed

Ramírez-Aldaba, Hugo; Vazquez-Arenas, Jorge; Sosa-Rodríguez, Fabiola S; Valdez-Pérez, Donato; Ruiz-Baca, Estela; García-Meza, Jessica Viridiana; Trejo-Córdova, Gabriel; Lara, René H

2017-08-01

Biofilm formation and evolution are key factors to consider to better understand the kinetics of arsenopyrite biooxidation. Chemical and surface analyses were carried out using Raman spectroscopy, scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), glow discharge spectroscopy (GDS), and protein analysis (i.e., quantification) in order to evaluate the formation of intermediate secondary compounds and any significant changes arising in the biofilm structure of Acidithiobacillus thiooxidans during a 120-h period of biooxidation. Results show that the biofilm first evolves from a low cell density structure (1 to 12 h) into a formation of microcolonies (24 to 120 h) and then finally becomes enclosed by a secondary compound matrix that includes pyrite (FeS 2 )-like, S n 2- /S 0 , and As 2 S 3 compounds, as shown by Raman and SEM-EDS. GDS analyses (concentration-depth profiles, i.e., 12 h) indicate significant differences for depth speciation between abiotic control and biooxidized surfaces, thus providing a quantitative assessment of surface-bulk changes across samples (i.e. reactivity and /or structure-activity relationship). Respectively, quantitative protein analyses and CLSM analyses suggest variations in the type of extracellular protein expressed and changes in the biofilm structure from hydrophilic (i.e., exopolysaccharides) to hydrophobic (i.e., lipids) due to arsenopyrite and cell interactions during the 120-h period of biooxidation. We suggest feasible environmental and industrial implications for arsenopyrite biooxidation based on the findings of this study.

Exploring the influence of a social ecological model on school-based physical activity.

PubMed

Langille, Jessie-Lee D; Rodgers, Wendy M

2010-12-01

Among rising rates of overweight and obesity, schools have become essential settings to promote health behaviors, such as physical activity (PA). As schools exist within a broader environment, the social ecological model (SEM) provided a framework to consider how different levels interact and influence PA. The purpose of this study was to provide insight on school-based PA promotion by investigating the integration between different levels of Emmons's SEM within one public school board in a large Canadian city. Interviews were conducted with participants from the government (n = 4), the public school board (n = 3), principals (n = 3), and teachers (n = 4) and analyzed to explore perspectives on the various levels of the model. The results suggested that higher level policies "trickled down" into the organizational level of the SEM but there was pivotal responsibility for schools to determine how to implement PA strategies. Furthermore, schools have difficulty implementing PA because of the continued priority of academic achievement.

Template construction grammar: from visual scene description to language comprehension and agrammatism.

PubMed

Barrès, Victor; Lee, Jinyong

2014-01-01

How does the language system coordinate with our visual system to yield flexible integration of linguistic, perceptual, and world-knowledge information when we communicate about the world we perceive? Schema theory is a computational framework that allows the simulation of perceptuo-motor coordination programs on the basis of known brain operating principles such as cooperative computation and distributed processing. We present first its application to a model of language production, SemRep/TCG, which combines a semantic representation of visual scenes (SemRep) with Template Construction Grammar (TCG) as a means to generate verbal descriptions of a scene from its associated SemRep graph. SemRep/TCG combines the neurocomputational framework of schema theory with the representational format of construction grammar in a model linking eye-tracking data to visual scene descriptions. We then offer a conceptual extension of TCG to include language comprehension and address data on the role of both world knowledge and grammatical semantics in the comprehension performances of agrammatic aphasic patients. This extension introduces a distinction between heavy and light semantics. The TCG model of language comprehension offers a computational framework to quantitatively analyze the distributed dynamics of language processes, focusing on the interactions between grammatical, world knowledge, and visual information. In particular, it reveals interesting implications for the understanding of the various patterns of comprehension performances of agrammatic aphasics measured using sentence-picture matching tasks. This new step in the life cycle of the model serves as a basis for exploring the specific challenges that neurolinguistic computational modeling poses to the neuroinformatics community.

30 CFR 250.1911 - What criteria for hazards analyses must my SEMS program meet?

Code of Federal Regulations, 2011 CFR

2011-07-01

..., AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE OIL AND GAS AND SULPHUR OPERATIONS IN THE OUTER... to the seabed (i.e., mobile offshore drilling units; floating production systems; floating production..., production, and transportation activities for oil, gas, or sulphur from areas leased in the OCS. Facilities...

30 CFR 250.1911 - What criteria for hazards analyses must my SEMS program meet?

Code of Federal Regulations, 2012 CFR

2012-07-01

..., DEPARTMENT OF THE INTERIOR OFFSHORE OIL AND GAS AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Safety...., mobile offshore drilling units; floating production systems; floating production, storage and offloading... transportation activities for oil, gas, or sulphur from areas leased in the OCS. Facilities also include DOI...

A Strategic Enrollment Management Approach to Studying High School Student Transition to a Two-Year College

ERIC Educational Resources Information Center

Wang, Yan; Ye, Feifei; Pilarzyk, Tom

2014-01-01

This study used a strategic enrollment management (SEM) approach to studying high school students' transition to a two-year college and their initial college success. Path analyses suggested two important findings: (a) clear career choices among students, family influence, academic preparedness, and college recruitment efforts predicted earlier…

Sem-Analysing Events: Towards a Cultural Pedagogy of Hope

ERIC Educational Resources Information Center

Semetsky, Inna

2007-01-01

This paper locates the concept of learning among real-life human experiences and events. Functioning as a sign, a meaningful event can be understood in terms of a cultural extra-linguistic "text." Reading and interpreting diverse cultural "texts" are equivalent to constructing and learning critical symbolic lessons embedded in a continuous process…

Structural, microstructural and vibrational analyses of the monoclinic tungstate BiLuWO6

NASA Astrophysics Data System (ADS)

Ait Ahsaine, H.; Taoufyq, A.; Patout, L.; Ezahri, M.; Benlhachemi, A.; Bakiz, B.; Villain, S.; Guinneton, F.; Gavarri, J.-R.

2014-10-01

The bismuth lutetium tungstate phase BiLuWO6 has been prepared using a solid state route with stoichiometric mixtures of oxide precursors. The obtained polycrystalline phase has been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. In the first step, the crystal structure has been refined using Rietveld method: the crystal cell was resolved using monoclinic system (parameters a, b, c, β) with space group A2/m. SEM images showed the presence of large crystallites with a constant local nominal composition (BiLuW). TEM analyses showed that the actual local structure could be better represented by a superlattice (a, 2b, c, β) associated with space groups P2 or P2/m. The Raman spectroscopy showed the presence of vibrational bands similar to those observed in the compounds BiREWO6 with RE=Y, Gd, Nd. However, these vibrational bands were characterized by large full width at half maximum, probably resulting from the long range Bi/Lu disorder and local WO6 octahedron distortions in the structure.

A collagen and elastic network in the wing of the bat.

PubMed

Holbrook, K A; Odland, G F

1978-05-01

Bundles of collagen fibrils, elastic fibres and fibroblasts are organized into a network that lies in the plane of a large portion of the bat wing. By ultrastructural (TEM and SEM) and biochemical analyses it was found that individual bundles of the net are similar to elastic ligaments. Although elastic fibres predominate, they are integrated and aligned in parallel with small bundles of collagen. A reticulum of fibroblasts, joined by focal junctions, forms a cellular framework throughout each bundle. Because of the unique features of the fibre bundles of the bat's wing, in particular their accessibility, and the parallel alignment of the collagen fibrils and elastic fibres in each easily isolatable fibre bundle, they should prove a most valuable model for connective tissue studies, particularly for the study of collagen-elastin interactions.

Observed emotion frequency versus intensity as predictors of socioemotional maladjustment.

PubMed

Hernández, Maciel M; Eisenberg, Nancy; Valiente, Carlos; Spinrad, Tracy L; VanSchyndel, Sarah K; Diaz, Anjolii; Berger, Rebecca H; Silva, Kassondra M; Southworth, Jody; Piña, Armando A

2015-12-01

The purpose of this study was to assess whether observed emotional frequency (the proportion of instances an emotion was observed) and intensity (the strength of an emotion when it was observed) uniquely predicted kindergartners' (N = 301) internalizing and externalizing problems. Analyses were tested in a structural equation modeling (SEM) framework with data from multireporters (reports of problem behaviors from teachers and parents) and naturalistic observations of emotion in the fall semester. For observed positive emotion, both frequency and intensity negatively predicted parent- or teacher-reported internalizing symptoms. Anger frequency positively predicted parent- and teacher-reported externalizing symptoms, whereas anger intensity positively predicted parent- and teacher-reported externalizing and parent-reported internalizing symptoms. The findings support the importance of examining both aspects of emotion when predicting maladjustment. (c) 2015 APA, all rights reserved).

Why Isn't Talent Development on the IEP? SEM and the Twice Exceptional Learner

ERIC Educational Resources Information Center

Baum, Susan; Novak, Cynthia

2010-01-01

Why isn't talent development included on the Individual Educational Plan of 2E students? Twice exceptional students have unique issues that respond especially well to a talent development approach especially within the context of the Schoolwide Enrichment Model. Through case studies and a review of successful projects using SEM with at risk…

The Application of SEM to Behavioral Research in Oncology: Past Accomplishments and Future Opportunities

ERIC Educational Resources Information Center

Schnoll, Robert A.; Fang, Carolyn Y.; Manne, Sharon L.

2004-01-01

The past decade has seen a tremendous growth in the use of structural equation modeling (SEM) to address research questions in 2 subfields of behavioral science: cancer prevention and control (e.g., determinants of cancer screening adherence) and behavioral oncology (e.g., determinants of psychosocial adjustment among cancer patients or…

Lessons Learned from My Students: The Impact of SEM Teaching and Learning on Affective Development

ERIC Educational Resources Information Center

Hebert, Thomas P.

2010-01-01

Through reflection on his years as an enrichment teacher in Schoolwide Enrichment Model (SEM) programs, the author describes significant ways the social and emotional development of his students was shaped by their involvement in enriched teaching and learning. Through portraits of his students engaged in Type II and Type III enrichment, the…

Assessing statistical differences between parameters estimates in Partial Least Squares path modeling.

PubMed

Rodríguez-Entrena, Macario; Schuberth, Florian; Gelhard, Carsten

2018-01-01

Structural equation modeling using partial least squares (PLS-SEM) has become a main-stream modeling approach in various disciplines. Nevertheless, prior literature still lacks a practical guidance on how to properly test for differences between parameter estimates. Whereas existing techniques such as parametric and non-parametric approaches in PLS multi-group analysis solely allow to assess differences between parameters that are estimated for different subpopulations, the study at hand introduces a technique that allows to also assess whether two parameter estimates that are derived from the same sample are statistically different. To illustrate this advancement to PLS-SEM, we particularly refer to a reduced version of the well-established technology acceptance model.

The PM2.5 capture of poly (lactic acid)/nano MOFs eletrospinning membrane with hydrophilic surface

NASA Astrophysics Data System (ADS)

Wang, Yating; Dai, Xiu; Li, Xu; Wang, Xinlong

2018-03-01

In this article, metal organic frameworks (MOFs) material is introduced in the poly (lactic acid) (PLA) by electrospinning to fabricate the nanocomposite membrane. The acrylic acid (AA) is grafted onto the membrane under UV light. The prepared membrane is studied by scanning electron microscopy (SEM), x-ray diffraction (XRD), thermogravimetry (TG), contact angle test and tensile strength test. The SEM image and XRD indicate that nano MOFs particles adhere to the membrane. Contact angle test shows that grafting AA on the composite fiber membrane improves its hydrophilicity effectively. TG analyses show that the particulate matter (PM) capture capacity of PLA membrane with 2 wt% ZIF-8 content is 22%, which rises to 37% after grafting.

Group 12 dithiocarbamate complexes: Synthesis, spectral studies and their use as precursors for metal sulfides nanoparticles and nanocomposites

NASA Astrophysics Data System (ADS)

Ajibade, Peter A.; Ejelonu, Benjamin C.

2013-09-01

Zn(II), Cd(II) and Hg(II) dithiocarbamate complexes have been synthesized and characterized by elemental analysis, thermogravimetric analysis, UV-Vis, FTIR, 1H- and 13C NMR spectroscopy. The complexes were thermolysed at 180 °C and used as single molecule precursors for the synthesis of HDA capped ZnS, CdS and HgS nanoparticles and polymethylmethacrylate (PMMA) nanocomposites. The optical and structural properties of the nanoparticles and nanocomposites were studied by UV-Vis, PL, XRD and SEM. The crystallites sizes of the nanoparticles varied between 3.03 and 23.45 nm. SEM and EDX analyses of the nanocomposites confirmed the presence of the nanoparticles in the polymer matrix.

A Brief Scale to Measure Problematic Sexually Explicit Media Consumption: Psychometric Properties of the Compulsive Pornography Consumption (CPC) Scale among Men who have Sex with Men

PubMed Central

Noor, Syed WB; Simon Rosser, B. R.; Erickson, Darin J.

2015-01-01

Although the phenomenon of hypersexuality has been described in the literature, and scales of compulsive sexual behavior have been published, the existing measures do not assess compulsive sexually explicit media (SEM) consumption. This study tested the psychometric properties of a new scale, the Compulsive Pornography Consumption (CPC). Exploratory and confirmatory factor analyses results showed good psychometric performance of a five item two factor preoccupation-compulsivity solution. As hypothesized, the scale correlates positively with compulsive sexual behavior, internalized homonegativity, and negatively with sexual self-esteem. The scale will enable researchers to investigate the etiologic factors of compulsive SEM use, and enable clinicians to assess problematic consumption. PMID:25838755

Chlorination Kinetics of Titanium Nitride for Production of Titanium Tetrachloride from Nitrided Ilmenite

NASA Astrophysics Data System (ADS)

Ahmadi, Eltefat; Rezan, Sheikh Abdul; Baharun, Norlia; Ramakrishnan, Sivakumar; Fauzi, Ahmad; Zhang, Guangqing

2017-10-01

The kinetics of chlorination of titanium nitride (TiN) was investigated in the temperature range of 523 K to 673 K (250 °C to 400 °C). The results showed that the extent of chlorination slightly increased with increasing temperature and decreasing particle size of titanium nitride at constant flow rate of N2-Cl2 gas mixture. At 523 K (250 °C), the extent of chlorination was 85.6 pct in 60 minutes whereas at 673 K (400 °C), it was 97.7 pct investigated by weight loss measurement and confirmed by ICP analyses. The experimental results indicated that a shrinking unreacted core model with mixed-control mechanism governed the chlorination rate. It was observed that the surface chemical reaction of chlorine gas on the surface of TiN particles was rate controlling in the initial stage and, during later stage, internal (pore) diffusion through the intermediate product layer was rate controlling step. Overall the process follows the mixed-control model incorporating both chemical reaction and internal diffusion control. The activation energy for the chlorination of TiN was found to be about 10.97 kJ mol-1. In processing TiCl4 from TiN and TiO0.02C0.13N0.85, the solids involved in the chlorination process were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy-dispersive X-ray spectrometer (EDX). The SEM/EDX results demonstrated the consumption of TiN particles with extent of chlorination that showed shrinking core behavior.

Astaxanthin modulates osteopontin and transforming growth factor β1 expression levels in a rat model of nephrolithiasis: a comparison with citrate administration.

PubMed

Alex, Manju; Sauganth Paul, M V; Abhilash, M; Mathews, Varghese V; Anilkumar, T V; Nair, R Harikumaran

2014-09-01

To evaluate the effect of astaxanthin on renal angiotensin-I converting enzyme (ACE) levels, osteopontin (OPN) and transforming growth factor β1 (TGF-β1) expressions and the extent of crystal deposition in experimentally induced calcium oxalate kidney stone disease in a male Wistar rat model. To compare the efficacy of astaxanthin treatment with a currently used treatment strategy (citrate administration) for kidney stones. The expression of OPN was assessed by immunohistochemistry. One step reverse transcriptase polymerase chain reaction followed by densitometry was used to assess renal OPN and TGF-β1 levels. Renal ACE levels were quantified by an enzyme-linked immunosorbent assay method. Crystal deposition in kidney was analysed by scanning electron microscopic (SEM)-energy-dispersive X-ray (EDX). The renal ACE levels and the expression of OPN and TGF-β1 were upregulated in the nephrolithiasis-induced rats. Astaxanthin treatment reduced renal ACE levels and the expression OPN and TGF-β1. SEM-EDX analysis showed that crystal deposition was reduced in the astaxanthin-treated nephrolithiatic group. Astaxanthin treatment was more effective than citrate administration in the regulation of renal ACE levels, OPN and TGF-β1 expressions. Astaxanthin administration reduced renal calcium oxalate crystal deposition possibly by modulating the renal renin-angiotensin system (RAS), which reduced the expression of OPN and TGF-β1 levels. Astaxanthin administration was more effective than citrate treatment in reducing crystal deposition and down-regulating the expression of OPN and TGF-β1. © 2013 The Authors. BJU International © 2013 BJU International.

A two scale analysis of tight sandstones

NASA Astrophysics Data System (ADS)

Adler, P. M.; Davy, C. A.; Song, Y.; Troadec, D.; Hauss, G.; Skoczylas, F.

2015-12-01

Tight sandstones have a low porosity and a very small permeability K. Available models for K do not compare well with measurements. These sandstones are made of SiO_2 grains, with a typical size of several hundreds of micron. These grains are separated by a network of micro-cracks, with sizes ranging between microns down to tens of nm. Therefore, the structure can be schematized by Voronoi polyhedra separated by plane and permeable polygonal micro-cracks. Our goal is to estimate K based on a two scale analysis and to compare the results to measurements. For a particular sample [2], local measurements on several scales include FIB/SEM [3], CMT and 2D SEM. FIB/SEM is selected because the peak pore size given by Mercury Intrusion Porosimetry is of 350nm. FIB/SEM imaging (with 50 nm voxel size) identifies an individual crack of 180nm average opening, whereas CMT provides a connected porosity (individual crack) for 60 nm voxel size, of 4 micron average opening. Numerical modelling is performed by combining the micro-crack network scale (given by 2D SEM) and the 3D micro-crack scale (given by either FIB/SEM or CMT). Estimates of the micro-crack density are derived from 2D SEM trace maps by counting the intersections with scanlines, the surface density of traces, and the number of fracture intersections. K is deduced by using a semi empirical formula valid for identical, isotropic and uniformly distributed fractures [1]. This value is proportional to the micro-crack transmissivity sigma. Sigma is determined by solving the Stokes equation in the micro-cracks measured by FIB/SEM or CMT. K is obtained by combining the two previous results. Good correlation with measured values on centimetric plugs is found when using sigma from CMT data. The results are discussed and further research is proposed. [1] Adler et al, Fractured porous media, Oxford Univ. Press, 2012. [2] Duan et al, Int. J. Rock Mech. Mining Sci., 65, p75, 2014. [3] Song et al, Marine and Petroleum Eng., 65, p63, 2015.

3DSEM++: Adaptive and intelligent 3D SEM surface reconstruction.

PubMed

Tafti, Ahmad P; Holz, Jessica D; Baghaie, Ahmadreza; Owen, Heather A; He, Max M; Yu, Zeyun

2016-08-01

Structural analysis of microscopic objects is a longstanding topic in several scientific disciplines, such as biological, mechanical, and materials sciences. The scanning electron microscope (SEM), as a promising imaging equipment has been around for decades to determine the surface properties (e.g., compositions or geometries) of specimens by achieving increased magnification, contrast, and resolution greater than one nanometer. Whereas SEM micrographs still remain two-dimensional (2D), many research and educational questions truly require knowledge and facts about their three-dimensional (3D) structures. 3D surface reconstruction from SEM images leads to remarkable understanding of microscopic surfaces, allowing informative and qualitative visualization of the samples being investigated. In this contribution, we integrate several computational technologies including machine learning, contrario methodology, and epipolar geometry to design and develop a novel and efficient method called 3DSEM++ for multi-view 3D SEM surface reconstruction in an adaptive and intelligent fashion. The experiments which have been performed on real and synthetic data assert the approach is able to reach a significant precision to both SEM extrinsic calibration and its 3D surface modeling. Copyright © 2016 Elsevier Ltd. All rights reserved.

Recent advances in 3D SEM surface reconstruction.

PubMed

Tafti, Ahmad P; Kirkpatrick, Andrew B; Alavi, Zahrasadat; Owen, Heather A; Yu, Zeyun

2015-11-01

The scanning electron microscope (SEM), as one of the most commonly used instruments in biology and material sciences, employs electrons instead of light to determine the surface properties of specimens. However, the SEM micrographs still remain 2D images. To effectively measure and visualize the surface attributes, we need to restore the 3D shape model from the SEM images. 3D surface reconstruction is a longstanding topic in microscopy vision as it offers quantitative and visual information for a variety of applications consisting medicine, pharmacology, chemistry, and mechanics. In this paper, we attempt to explain the expanding body of the work in this area, including a discussion of recent techniques and algorithms. With the present work, we also enhance the reliability, accuracy, and speed of 3D SEM surface reconstruction by designing and developing an optimized multi-view framework. We then consider several real-world experiments as well as synthetic data to examine the qualitative and quantitative attributes of our proposed framework. Furthermore, we present a taxonomy of 3D SEM surface reconstruction approaches and address several challenging issues as part of our future work. Copyright © 2015 Elsevier Ltd. All rights reserved.

In Situ Characterization of Boehmite Particles in Water Using Liquid SEM.

PubMed

Yao, Juan; Arey, Bruce W; Yang, Li; Zhang, Fei; Komorek, Rachel; Chun, Jaehun; Yu, Xiao-Ying

2017-09-27

In situ imaging and elemental analysis of boehmite (AlOOH) particles in water is realized using the System for Analysis at the Liquid Vacuum Interface (SALVI) and Scanning Electron Microscopy (SEM). This paper describes the method and key steps in integrating the vacuum compatible SAVLI to SEM and obtaining secondary electron (SE) images of particles in liquid in high vacuum. Energy dispersive x-ray spectroscopy (EDX) is used to obtain elemental analysis of particles in liquid and control samples including deionized (DI) water only and an empty channel as well. Synthesized boehmite (AlOOH) particles suspended in liquid are used as a model in the liquid SEM illustration. The results demonstrate that the particles can be imaged in the SE mode with good resolution (i.e., 400 nm). The AlOOH EDX spectrum shows significant signal from the aluminum (Al) when compared with the DI water and the empty channel control. In situ liquid SEM is a powerful technique to study particles in liquid with many exciting applications. This procedure aims to provide technical know-how in order to conduct liquid SEM imaging and EDX analysis using SALVI and to reduce potential pitfalls when using this approach.

Reliability and Validity of the Telephone-Based eHealth Literacy Scale Among Older Adults: Cross-Sectional Survey.

PubMed

Stellefson, Michael; Paige, Samantha R; Tennant, Bethany; Alber, Julia M; Chaney, Beth H; Chaney, Don; Grossman, Suzanne

2017-10-26

Only a handful of studies have examined reliability and validity evidence of scores produced by the 8-item eHealth literacy Scale (eHEALS) among older adults. Older adults are generally more comfortable responding to survey items when asked by a real person rather than by completing self-administered paper-and-pencil or online questionnaires. However, no studies have explored the psychometrics of this scale when administered to older adults over the telephone. The objective of our study was to examine the reliability and internal structure of eHEALS data collected from older adults aged 50 years or older responding to items over the telephone. Respondents (N=283) completed eHEALS as part of a cross-sectional landline telephone survey. Exploratory structural equation modeling (E-SEM) analyses examined model fit of eHEALS scores with 1-, 2-, and 3-factor structures. Subsequent analyses based on the partial credit model explored the internal structure of eHEALS data. Compared with 1- and 2-factor models, the 3-factor eHEALS structure showed the best global E-SEM model fit indices (root mean square error of approximation=.07; comparative fit index=1.0; Tucker-Lewis index=1.0). Nonetheless, the 3 factors were highly correlated (r range .36 to .65). Item analyses revealed that eHEALS items 2 through 5 were overfit to a minor degree (mean square infit/outfit values <1.0; t statistics less than -2.0), but the internal structure of Likert scale response options functioned as expected. Overfitting eHEALS items (2-5) displayed a similar degree of information for respondents at similar points on the latent continuum. Test information curves suggested that eHEALS may capture more information about older adults at the higher end of the latent continuum (ie, those with high eHealth literacy) than at the lower end of the continuum (ie, those with low eHealth literacy). Item reliability (value=.92) and item separation (value=11.31) estimates indicated that eHEALS responses were reliable and stable. Results support administering eHEALS over the telephone when surveying older adults regarding their use of the Internet for health information. eHEALS scores best captured 3 factors (or subscales) to measure eHealth literacy in older adults; however, statistically significant correlations between these 3 factors suggest an overarching unidimensional structure with 3 underlying dimensions. As older adults continue to use the Internet more frequently to find and evaluate health information, it will be important to consider modifying the original eHEALS to adequately measure societal shifts in online health information seeking among aging populations. ©Michael Stellefson, Samantha R Paige, Bethany Tennant, Julia M Alber, Beth H Chaney, Don Chaney, Suzanne Grossman. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 26.10.2017.

Comparison of two dental implant surface modifications on implants with same macrodesign: an experimental study in the pelvic sheep model.

PubMed

Ernst, Sabrina; Stübinger, Stefan; Schüpbach, Peter; Sidler, Michéle; Klein, Karina; Ferguson, Stephen J; von Rechenberg, Brigitte

2015-08-01

The aim of this study was to compare two different surfaces of one uniform macro-implant design in order to focus exclusively on the osseointegration properties after 2, 4 and 8 weeks and to discuss the animal model chosen. In six mature sheep, n = 36 implants with a highly crystalline and phosphate-enriched anodized titanium oxide surface (TiU) and n = 36 implants with a hydrophilic, sandblasted, large grit and acid-etched surface (SLA) were placed in the pelvic bone. TiU implants were custom-made to match the SLA implant design. The implant stability and bone-to-implant contact (BIC) were assessed by resonance frequency (ISQ), backscatter scanning electron microscopy (B-SEM), light microscopy (LM), micro-CT and intravital fluorochrome staining. Biomechanical removal torque testing was performed. Overall, no statistically significant differences in BIC total (trabecular + cortical) between TiU and SLA were found via LM and B-SEM. BIC values (B-SEM; LM) in both groups revealed a steady rise in trabecular bone attachment to the implant surface after 2, 4 and 8 weeks. In the 2- to 4-week time interval in the TiU group (P = 0.005) as well as in the SLA group (P = 0.01), a statistically significant increase in BIC trabecular could be observed via LM. B-SEM values confirmed the statistically significant increase for TiU (P = 0.001). In both groups, BIC trabecular values after 8 weeks were significantly higher (P ≤ 0.05) than after 2 weeks (B-SEM; LM). Biomechanical data confirmed the histological data. The two surfaces proved comparable osseointegration in this sheep model. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Choices in higher education: Majoring in and changing from the sciences

NASA Astrophysics Data System (ADS)

Minear, Nancy Ann

This dissertation addresses patterns of retention of undergraduate science, engineering and mathematics (SEM) students, with special attention paid to female and under represented minority students. As such, the study is focused on issues related to academic discipline and institutional retention, rather than the retention of students in the overall system of higher education. While previous retention studies have little to say about rates of retention that are specific to the sciences (or any other specific area of study) or employ models that rely on students' performance at the college level, this work address both points by identifying the post secondary academic performance characteristics of persisters and non-persisters in the sciences by gender, ethnicity and matriculating major as well as identifying introductory SEM course requirements that prevent students from persisting in sciencegender, ethnicity and matriculating major as well as identifying introductory SEM course requirements that prevent students from persisting in science majors. A secondary goal of investigating the usefulness of institutional records for retention research is addressed. Models produced for the entire population and selected subpopulations consistently classified higher-performing (both SEM and non-SEM grade point averages) students into Bachelor of Science categories using the number of Introductory Chemistry courses attempted at the university. For lower performing students, those with more introductory chemistry courses were classified as changing majors out of the sciences, and in general as completing a Bachelor of Arts degree. Performance in gatekeeper courses as a predictor of terminal academic status was limited to Introductory Physics for a small number of cases. Performance in Introductory Calculus and Introductory Chemistry were not consistently utilized as predictor variables. The models produced for various subpopulations (women, ethnic groups and matriculation major) utilized the same set of predictor variables with varying cutpoints for classification.

Spectral-element global waveform tomography: A second-generation upper-mantle model

NASA Astrophysics Data System (ADS)

French, S. W.; Lekic, V.; Romanowicz, B. A.

2012-12-01

The SEMum model of Lekic and Romanowicz (2011a) was the first global upper-mantle VS model obtained using whole-waveform inversion with spectral element (SEM: Komatitsch and Vilotte, 1998) forward modeling of time domain three component waveforms. SEMum exhibits stronger amplitudes of heterogeneity in the upper 200km of the mantle compared to previous global models - particularly with respect to low-velocity anomalies. To make SEM-based waveform inversion tractable at global scales, SEMum was developed using: (1) a version of SEM coupled to 1D mode computation in the earth's core (C-SEM, Capdeville et al., 2003); (2) asymptotic normal-mode sensitivity kernels, incorporating multiple forward scattering and finite-frequency effects in the great-circle plane (NACT: Li and Romanowicz, 1995); and (3) a smooth anisotropic crustal layer of uniform 60km thickness, designed to match global surface-wave dispersion while reducing the cost of time integration in the SEM. The use of asymptotic kernels reduced the number of SEM computations considerably (≥ 3x) relative to purely numerical approaches (e.g. Tarantola, 1984), while remaining sufficiently accurate at the periods of interest (down to 60s). However, while the choice of a 60km crustal-layer thickness is justifiable in the continents, it can complicate interpretation of shallow oceanic upper-mantle structure. We here present an update to the SEMum model, designed primarily to address these concerns. The resulting model, SEMum2, was derived using a crustal layer that again fits global surface-wave dispersion, but with a more geologically consistent laterally varying thickness: approximately honoring Crust2.0 (Bassin, et al., 2000) Moho depth in the continents, while saturating at 30km in the oceans. We demonstrate that this approach does not bias our upper mantle model, which is constrained not only by fundamental mode surface waves, but also by overtone waveforms. We have also improved our data-selection and assimilation scheme, more readily allowing for additional and higher-quality data to be incorporated into our inversion as the model improves. Further, we have been able to refine the parameterization of the isotropic component of our model, previously limited by our ability to solve the large dense linear system that governs model updates (Tarantola and Valette, 1982). The construction of SEMum2 involved 3 additional inversion iterations away from SEMum. Overall, the combined effect of these improvements confirms and validates the general structure of the original SEMum. Model amplitudes remain an impressive feature in SEMum2, wherein peak-to-peak variation in VS can exceed 15% in close lateral juxtaposition. Further, many intriguing structures present in SEMum are now imaged with improved resolution in the updated model. In particular, the geographic extents of the anomalous oceanic cluster identified by Lekic and Romanowicz (2011b) are consistent with our findings and now allow us to further identify alternating bands of lower and higher velocities in the 200-300km depth range beneath the Pacific basin, with a characteristic spacing of ˜2000km normal to absolute plate motion. Possible dynamic interpretation of these and other features in the ocean basins is explored in a companion presentation (Romanowicz et al., this meeting).

Forensic microanalysis of Manhattan Project legacy radioactive wastes in St. Louis, MO.

PubMed

Kaltofen, Marco; Alvarez, Robert; Hixson, Lucas W

2018-06-01

Radioactive particulate matter (RPM) in St Louis, MO, area surface soils, house dusts and sediments was examined by scanning electron microscopy with energy dispersive X-ray analysis. Analyses found RPM containing 238 U and decay products (up to 46 wt%), and a distinct second form of RPM containing 230 Th and decay products (up to 15.6 wt%). The SEM-EDS analyses found similar RPM in Manhattan Project-era radioactive wastes and indoor dusts in surrounding homes. Copyright © 2018 Elsevier Ltd. All rights reserved.

Using structural equation modeling to detect response shifts and true change in discrete variables: an application to the items of the SF-36.

PubMed

Verdam, Mathilde G E; Oort, Frans J; Sprangers, Mirjam A G

2016-06-01

The structural equation modeling (SEM) approach for detection of response shift (Oort in Qual Life Res 14:587-598, 2005. doi: 10.1007/s11136-004-0830-y ) is especially suited for continuous data, e.g., questionnaire scales. The present objective is to explain how the SEM approach can be applied to discrete data and to illustrate response shift detection in items measuring health-related quality of life (HRQL) of cancer patients. The SEM approach for discrete data includes two stages: (1) establishing a model of underlying continuous variables that represent the observed discrete variables, (2) using these underlying continuous variables to establish a common factor model for the detection of response shift and to assess true change. The proposed SEM approach was illustrated with data of 485 cancer patients whose HRQL was measured with the SF-36, before and after start of antineoplastic treatment. Response shift effects were detected in items of the subscales mental health, physical functioning, role limitations due to physical health, and bodily pain. Recalibration response shifts indicated that patients experienced relatively fewer limitations with "bathing or dressing yourself" (effect size d = 0.51) and less "nervousness" (d = 0.30), but more "pain" (d = -0.23) and less "happiness" (d = -0.16) after antineoplastic treatment as compared to the other symptoms of the same subscale. Overall, patients' mental health improved, while their physical health, vitality, and social functioning deteriorated. No change was found for the other subscales of the SF-36. The proposed SEM approach to discrete data enables response shift detection at the item level. This will lead to a better understanding of the response shift phenomena at the item level and therefore enhances interpretation of change in the area of HRQL.

The impact of online visual on users' motivation and behavioural intention - A comparison between persuasive and non-persuasive visuals

NASA Astrophysics Data System (ADS)

Ibrahim, Nurulhuda; Shiratuddin, Mohd Fairuz; Wong, Kok Wai

2016-08-01

Research related to the first impression has highlighted the importance of visual appeal in influencing the favourable attitude towards a website. In the perspective of impression formation, it is proposed that the users are actually attracted to certain characteristics or aspects of the visual properties of a website, while ignoring the rests. Therefore, this study aims to investigate which visual strongly appeals to the users by comparing the impact of common visuals with the persuasive visuals. The principles of social influence are proposed as the added value to the persuasiveness of the web visuals. An experimental study is conducted and the PLS-SEM method is employed to analyse the obtained data. The result of the exploratory analyses demonstrated that the structural model has better quality when tested with persuasive data sample compared to non-persuasive data sample, evident with stronger coefficient of determination and path coefficients. Thus, it is concluded that persuasive visual provides better impact towards users' attitude and behavioural intention of a website.

Analysis on factors affecting household customers decision in using electricity at peak time and its correlation towards saving electricity

NASA Astrophysics Data System (ADS)

Pasasa, Linus; Marbun, Parlin; Mariza, Ita

2015-09-01

The purpose of this paper is to study and analyse the factors affecting customer decisions in using electricity at peak-load hours (between 17.00 to 22.00 WIB) and their behaviors towards electricity conservation in Indonesian household. The underlying rationale is to influence a reduction in energy consumption by stimulating energy saving behaviors, thereby reducing the impact of energy use on the environment. How is the correlation between the decisions in using electricity during peak load hours with the household customer's behavior towards saving electricity? The primary data is obtained by distributing questionnaires to customers of PT. PLN Jakarta Raya and Tangerang Distribution from Household segment. The data is analysed using the Structural Equation Model (SEM) and AMOS Software. The research is finding that all factors (Personal, Social, PLN Services, Psychological, and Cultural) are positively influence customer decision in using electricity at peak load hours. There is a correlation between the decisions in using electricity during peak load hours with the household customer's behavior towards saving electricity.

Neural Network for Nanoscience Scanning Electron Microscope Image Recognition.

PubMed

Modarres, Mohammad Hadi; Aversa, Rossella; Cozzini, Stefano; Ciancio, Regina; Leto, Angelo; Brandino, Giuseppe Piero

2017-10-16

In this paper we applied transfer learning techniques for image recognition, automatic categorization, and labeling of nanoscience images obtained by scanning electron microscope (SEM). Roughly 20,000 SEM images were manually classified into 10 categories to form a labeled training set, which can be used as a reference set for future applications of deep learning enhanced algorithms in the nanoscience domain. The categories chosen spanned the range of 0-Dimensional (0D) objects such as particles, 1D nanowires and fibres, 2D films and coated surfaces, and 3D patterned surfaces such as pillars. The training set was used to retrain on the SEM dataset and to compare many convolutional neural network models (Inception-v3, Inception-v4, ResNet). We obtained compatible results by performing a feature extraction of the different models on the same dataset. We performed additional analysis of the classifier on a second test set to further investigate the results both on particular cases and from a statistical point of view. Our algorithm was able to successfully classify around 90% of a test dataset consisting of SEM images, while reduced accuracy was found in the case of images at the boundary between two categories or containing elements of multiple categories. In these cases, the image classification did not identify a predominant category with a high score. We used the statistical outcomes from testing to deploy a semi-automatic workflow able to classify and label images generated by the SEM. Finally, a separate training was performed to determine the volume fraction of coherently aligned nanowires in SEM images. The results were compared with what was obtained using the Local Gradient Orientation method. This example demonstrates the versatility and the potential of transfer learning to address specific tasks of interest in nanoscience applications.

Alpha decay calculations with a new formula

NASA Astrophysics Data System (ADS)

Akrawy, D. T.; Poenaru, D. N.

2017-10-01

A new semi-empirical formula for calculations of α decay half-lives is presented. It was derived from the Royer relationship by introducing new parameters which are fixed by fit to a set of experimental data. We are using three sets: set A with 130 e-e (even-even), 119 e-o (even-odd), 109 o-e, and 96 o-o, set B with 188 e-e, 147 e-o, 131 o-e and 114 o-o, and set C with 136 e-e, 84 e-o, 76 o-e and 48 o-o alpha emitters. A comparison of results obtained with the new formula (newF) and the following well known relationships: semiempirical relationship based on fission theory (semFIS), analytical superasymmetric fission (ASAF) model and universal formula (UNIV) made in terms of rms standard deviation. We also introduced a weighted mean value of this quantity, allowing us to compare the global properties of a given model. For set B the order of the four models is the following: semFIS, UNIV, newF and ASAF. Nevertheless for even-even alpha emitters, UNIV gives the second best result after semFIS, and for odd-even parents the second is newF. Despite its simplicity in comparison with semFIS, newF, presented in this article, behaves quite well, competing with the other well known relationships.

A structural equation modeling of executive functions, IQ and mathematical skills in primary students: Differential effects on number production, mental calculus and arithmetical problems.

PubMed

Arán Filippetti, Vanessa; Richaud, María Cristina

2017-10-01

Though the relationship between executive functions (EFs) and mathematical skills has been well documented, little is known about how both EFs and IQ differentially support diverse math domains in primary students. Inconsistency of results may be due to the statistical techniques employed, specifically, if the analysis is conducted with observed variables, i.e., regression analysis, or at the latent level, i.e., structural equation modeling (SEM). The current study explores the contribution of both EFs and IQ in mathematics through an SEM approach. A total of 118 8- to 12-year-olds were administered measures of EFs, crystallized (Gc) and fluid (Gf) intelligence, and math abilities (i.e., number production, mental calculus and arithmetical problem-solving). Confirmatory factor analysis (CFA) offered support for the three-factor solution of EFs: (1) working memory (WM), (2) shifting, and (3) inhibition. Regarding the relationship among EFs, IQ and math abilities, the results of the SEM analysis showed that (i) WM and age predict number production and mental calculus, and (ii) shifting and sex predict arithmetical problem-solving. In all of the SEM models, EFs partially or totally mediated the relationship between IQ, age and math achievement. These results suggest that EFs differentially supports math abilities in primary-school children and is a more significant predictor of math achievement than IQ level.

Preferences for Condomless Sex in Sexually Explicit Media Among Black/African American Men Who Have Sex with Men: Implications for HIV Prevention.

PubMed

Nelson, Kimberly M; Eaton, Lisa A; Gamarel, Kristi E

2017-05-01

Accumulating evidence suggests that viewing sexually explicit media (SEM; i.e., pornography) may be related to the sexual behaviors of men who have sex with men (MSM). Furthermore, stereotypical depictions of Black/African American MSM engaging in sexual risk behaviors in SEM may serve to normalize condomless sex, reinforce low peer norms around condom use, and facilitate HIV risk taking among Black/African American MSM. Despite this evidence, very little is known about the correlates of SEM consumption among Black/African American MSM, including HIV risk behaviors and their relation to preferences for viewing condomless sex in SEM. Participants were 653 HIV-seronegative Black-identified MSM ages 18-62 (M 33.58, SD 11.01) who completed a cross-sectional survey as a part of a HIV prevention trial in Atlanta, Georgia. Over three-quarters of the men (n = 514) reported a preference for condomless sex in SEM. In multivariate models, engaging in serodiscordant condomless sex was not significantly associated with preferences for condomless sex in SEM; however, men who self-identified as bisexual, engaged in transactional sex, and reported greater agreement with sexual risk cognitions (i.e., heat-of-the-moment thoughts about condom use) had significantly greater odds of reporting a preference for condomless sex in SEM. Study findings highlight the need for future research exploring the role of SEM in the sexual health of Black/African American MSM, including the extent to which SEM exposure alters norms and expectations about sexual behaviors among Black/African American MSM and how this might be addressed in HIV prevention programs.

Preferences for condomless sex in sexually explicit media among Black/African American men who have sex with men: Implications for HIV prevention

PubMed Central

Nelson, Kimberly M.; Eaton, Lisa A.; Gamarel, Kristi E.

2016-01-01

Accumulating evidence suggests that viewing sexually explicit media (SEM; i.e., pornography) may be related to the sexual behaviors of men who have sex with men (MSM). Furthermore, stereotypical depictions of Black/African American MSM engaging in sexual risk behaviors in SEM may serve to normalize condomless sex, reinforce low peer norms around condom use, and facilitate HIV risk-taking among Black/African American MSM. Despite this evidence, very little is known about the correlates of SEM consumption among Black/African American MSM, including HIV risk behaviors and their relation to preferences for viewing condomless sex in SEM. Participants were 653 HIV-seronegative Black-identified MSM ages 18 to 62 (M = 33.58, SD = 11.01) who completed a cross-sectional survey as a part of a HIV-prevention trial in Atlanta, Georgia. Over three-quarters of the men (n = 514) reported a preference for condomless sex in SEM. In multivariate models, engaging in serodiscordant condomless sex was not significantly associated with preferences for condomless sex in SEM; however, men who self-identified as bisexual, engaged in transactional sex, and reported greater agreement with sexual risk cognitions (i.e., heat of the moment thoughts about condom use) has significantly greater odds of reporting a preference for condomless sex in SEM. Study findings highlight the need for future research exploring the role of SEM in the sexual health of Black/African American MSM, including the extent to which SEM exposure alters norms and expectations about sexual behaviors among Black/African American MSM and how this might be addressed in HIV prevention programs. PMID:27987085

Fabrication and characterization of aluminium hybrid composites reinforced with fly ash and silicon carbide through powder metallurgy

NASA Astrophysics Data System (ADS)

Bilal Naim Shaikh, Mohd; Arif, Sajjad; Arif Siddiqui, M.

2018-04-01

This paper reports the fabrication and characterization of aluminium hybrid composites (AMCs) reinforced with commonly available and inexpensive fly ash (FA, 0, 5, 10 and 15 wt.%) particles along silicon carbide (SiC) using powder metallurgy process. Scanning electron microscopy (SEM) and x-ray diffraction (XRD) were employed for microstructural characterization and phase identification respectively. Wear behaviour were investigated using pin-on-disc wear tester for the different combinations of wear parameters like load (10, 20 and 30 N), sliding speed (1.5, 2 and 2.5 m s‑1) and sliding distance (300, 600 and 900 m). SEM confirms the uniform distribution of FA and SiC in aluminium matrix. The hardness of Al/SiC/FA is increased by 20%–25% while wear rate decreased by 15%–40%. From wear analysis, sliding distance was the least significant parameter influencing the wear loss followed by applied load and sliding speed. To identify the mechanism of wear, worn out surface were also analysed by SEM.

Biosorption of Fe(II) and Mn(II) Ions from Aqueous Solution by Rice Husk Ash

PubMed Central

Zhao, Jiaying; Jiang, Zhao; Shan, Dexin; Lu, Yan

2014-01-01

Rice husk ash (RHA), an agricultural waste, was used as biosorbent for the removal of Iron(II) and Manganese(II) ions from aqueous solutions. The structural and morphological characteristics of RHA and its elemental compositions before and after adsorption of Fe(II) and Mn(II) were determined by scanning electron microscopic (SEM) and X-ray fluorescence (XRF) analyses. Batch experiments were carried out to determine the influence of initial pH, contact time, adsorbent dosage, and initial concentration on the removal of Fe(II) and Mn(II) ions. Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) models were applied to describe the biosorption isotherm of the metal ions by RHA. The correlation coefficient (R 2) of Langmuir and Freundlich isotherm models equals 0.995 and 0.901 for Fe(II), 0.9862 and 0.8924 for Mn(II), respectively, so the Langmuir model fitted the equilibrium data better than the Freundlich isotherm model. The mean free energy values evaluated from the D-R model indicated that the biosorption of Fe(II) and Mn(II) onto RHA was physical in nature. Experimental data also showed that the biosorption processes of both metal ions complied with the pseudo-second-order kinetics. PMID:24982918

Identification and significance of accessory minerals from a bituminous coal

USGS Publications Warehouse

Finkelman, R.B.; Stanton, R.W.

1978-01-01

A scanning electron microscope (SEM) has been used to study the in situ accessory minerals in polished blocks and pellets of petrographically analysed samples of the Waynesburg coal (hvb). Individual grains from the low-temperature ash (LTA) of the same coal were also studied. The visual resolution of the SEM permitted the detection of submicron mineral grains, which could then be analysed by the attached energy-dispersive system. Emphasis was placed on the highly reflective grains in the carbominerite bands. Among the most abundant accessory minerals observed were rutile, zircon, and rare-earth-bearing minerals. Small (1-5 ??m) particles of what may be authigenic iron-rich chromite and a nickel silicate form rims on quartz grains. The SEM also permits the observation of grain morphology and mineral intergrowths. These data are useful in determining authigenicity and diagenic alteration. Substances in density splits of LTA include authigenic, detrital, extraterrestrial magnetite, tourmaline, and evaporite (?) minerals, and a fluorine-bearing amphibole. This analytical approach allows the determination of specific sites for many of the trace elements in coals. In the Waynesburg coal, most of the chromium is in the iron-chromium rims, the fluorine is in the amphibole, and the rare-earth elements are in rare-earth-bearing minerals. The ability to relate trace-element data to specific minerals will aid in predicting the behaviour of elements in coal during combustion, liquefaction, gasification, weathering, and leaching processes. This ability also permits insight into the degree of mobility of these elements in coal and provides clues to sedimentological and diagenetic conditions. ?? 1978.

Using the Partial Credit Model to Evaluate the Student Engagement in Mathematics Scale

ERIC Educational Resources Information Center

Leis, Micela; Schmidt, Karen M.; Rimm-Kaufman, Sara E.

2015-01-01

The Student Engagement in Mathematics Scale (SEMS) is a self-report measure that was created to assess three dimensions of student engagement (social, emotional, and cognitive) in mathematics based on a single day of class. In the current study, the SEMS was administered to a sample of 360 fifth graders from a large Mid-Atlantic district. The…

Effects of Two Instructional Approaches on Skill Development, Knowledge, and Game Performance

ERIC Educational Resources Information Center

Pritchard, Tony; Hawkins, Andrew; Wiegand, Robert; Metzler, Jonathan N.

2008-01-01

Two instructional approaches that have been of interest in promoting sport have been the Sport Education Model (SEM) and the Traditional Style (TS) of teaching physical education. The purpose of this study was to investigate how SEM and TS would affect skill development, knowledge, and game performance for volleyball at the secondary level. A 2 x…

SEM with Missing Data and Unknown Population Distributions Using Two-Stage ML: Theory and Its Application

ERIC Educational Resources Information Center

Yuan, Ke-Hai; Lu, Laura

2008-01-01

This article provides the theory and application of the 2-stage maximum likelihood (ML) procedure for structural equation modeling (SEM) with missing data. The validity of this procedure does not require the assumption of a normally distributed population. When the population is normally distributed and all missing data are missing at random…

The Structure of Memory in Infants and Toddlers: An SEM Study with Full-Terms and Preterms

ERIC Educational Resources Information Center

Rose, Susan A.; Feldman, Judith F.; Jankowski, Jeffery J.; Van Rossem, Ronan

2011-01-01

There is considerable dispute about the nature of infant memory. Using SEM models, we examined whether popular characterizations of the structure of adult memory, including the two-process theory of recognition, are applicable in the infant and toddler years. The participants were a cohort of preterms and full-terms assessed longitudinally--at 1,…

Symposium N: Materials and Devices for Thermal-to-Electric Energy Conversion

DTIC Science & Technology

2010-08-24

X - ray diffraction, transmission electron microscopy, scanning electron microscopy, and dynamic light scattering. Thermal conductivity measurements...SEM), X - ray diffraction (XRD) measurements as well as Raman spectroscopy. The results from these techniques indicate a clear modification...was examined by using scanning electron microscope (SEM; HITACHI S-4500 model) attached with an energy dispersive x - ray spectroscopy. The electrical

Mid-term variation of vertical distribution of acid volatile sulphide and simultaneously extracted metals in sediment cores from Lake Albufera (Valencia, Spain).

PubMed

Hernández-Crespo, Carmen; Martín, Miguel

2013-11-01

Lake Albufera is one of the most eutrophic bodies of water in Spain due to point and diffuse pollution over past decades, and its sediments are likely to be anoxic because of high organic matter flux. Hence, sulphides can play an important role in limiting the mobility of heavy metals. This study aimed to study the vertical variation of acid volatile sulphide (AVS) and simultaneously extracted metals (SEM) in sediment cores collected from Lake Albufera; other sediment characteristics, such as organic matter, biochemical oxygen, demand or total metals, were also studied. Three sites were selected, and four sampling campaigns were performed to study spatial and temporal variation as well as to obtain information regarding historical variation in the composition of sediments. AVS and SEM were analysed by the purge-and-trap method. The vertical distribution of AVS and SEM varied depending on the sampling site-concentrations of AVS and SEM were higher at sites close to mouths of inflowing channels. A decreasing trend of AVS has been found at these sites over time: In the two first samplings, AVS increased with depth reaching maximum concentrations of 40 and 21 μmol g(-1), but from then on AVS were lower and decreased with depth. SEM decreased with depth from 3 μmol g(-1) in surface layers to approximately 1 μmol g(-1) at deeper segments at these sites. However, the central site was more uniform with respect to depth as well as with time; it presented lower values of SEM and AVS (mean 0.9 and 2.0 μmol g(-1) respectively), and the maximum value of AVS (7 μmol g(-1)) was found at the top layer (0-3 cm). According to the (SEM-AVS)/fOC approach, every site, and throughout the cores, can be classified as containing nontoxic metals because the values were <130 μmol g(-1).

A selective biomarker for confirming nitrofurazone residues in crab and shrimp using ultra-performance liquid chromatography-tandem mass spectrometry.

PubMed

Zhang, Shuai; Guo, Yuanming; Yan, Zhongyong; Sun, Xiumei; Zhang, Xiaojun

2015-12-01

Reliably detecting nitrofurazone (NFZ) residues in farmed crab and shrimp was previously hindered by lack of appropriately specific analytical methodology. Parent NFZ rapidly breaks down in meat, and the commonly used side-chain metabolite, semicarbazide (SEM), is non-specific as it occurs naturally in crustacean shell often leading to 'false positive' detections in meat. Using 5-nitro-2-furaldehyde (NF) as marker metabolite, following pre-column derivatization with 2,4-dinitrophenylhydrazine (DNPH), ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis in negative electrospray ionization mode enabled confirmation of NFZ residues in deliberately treated whole crab, crab meat and shrimp meat, with a limit of detection (LOD) and limit of quantification (LOQ) below 1 ng g(-1). Meanwhile, the derivatives of DNPH-NF were synthesized for the first time, purified by preparative liquid chromatography and structure characterized with nuclear magnetic resonance spectroscopy ((1)H-NMR). The purity of derivative was checked by ultra-performance liquid chromatography-tunable ultraviolet (UPLC-TUV), and the contents were beyond 99.9%. For comparison purposes, crustacean samples were analysed using both NF and SEM marker metabolites. NFZ treatment was revealed by both NF and SEM marker metabolites, but untreated crab also showed measurable levels of SEM which could potentially be misinterpreted as evidence of illegal NFZ use.

AFM and SEM study of the effects of etching on IPS-Empress 2 TM dental ceramic

NASA Astrophysics Data System (ADS)

Luo, X.-P.; Silikas, N.; Allaf, M.; Wilson, N. H. F.; Watts, D. C.

2001-10-01

The aim of this study was to investigate the effects of increasing etching time on the surface of the new dental material, IPS-Empress 2 TM glass ceramic. Twenty one IPS-Empress 2 TM glass ceramic samples were made from IPS-Empress 2 TM ingots through lost-wax, hot-pressed ceramic fabrication technology. All samples were highly polished and cleaned ultrasonically for 5 min in acetone before and after etching with 9.6% hydrofluoric acid gel. The etching times were 0, 10, 20, 30, 60, 90 and 120 s respectively. Microstructure was analysed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) was used to evaluate the surface roughness and topography. Observations with SEM showed that etching with hydrofluoric acid resulted in preferential dissolution of glass matrix, and that partially supported crystals within the glass matrix were lost with increasing etching time. AFM measurements indicated that etching increased the surface roughness of the glass-ceramic. A simple least-squares linear regression was used to establish a relationship between surface roughness parameters ( Ra, RMS), and etching time, for which r2>0.94. This study demonstrates the benefits of combining two microscopic methods for a better understanding of the surface. SEM showed the mode of action of hydrofluoric acid on the ceramic and AFM provided valuable data regarding the extent of surface degradation relative to etching time.

Resilience or hope? Incremental and convergent validity of the resilience scale for adults (RSA) and the Herth hope scale (HHS) in the prediction of anxiety and depression.

PubMed

Morote, Roxanna; Hjemdal, Odin; Krysinska, Karolina; Martinez Uribe, Patricia; Corveleyn, Jozef

2017-10-27

Hope and resilience protect against inner vulnerabilities or harsh life circumstances; they explain individual differences in physical or mental health outcomes under high stress. They have been studied in complementary or competing theoretical frameworks; therefore, the study of measures of hope and resilience should be undertaken prior to explore if they are truly value-added for research. This study investigates the convergent and incremental validity of the Resilience Scale for Adults (RSA) and the Herth Hope Scale (HHS), in the prediction of anxiety and depression (HSCL-25). Participants in this community-based sample are 762 adults from 18 to 74 years old. They answered the RSA, HHS, Spanish Language Stressful Life-Events Checklist (SL-SLE), and the Hopkins Symptom Checklist-25 (HSCL-25). Incremental validity analyses combined hierarchical regression and structural equation models (SEM). First, hierarchical regression models were compared based on three criteria (R 2 Diff., ΔF, and semi-partial r), then the direct effect of resilience on affective symptoms was compared with the mediated effect of resilience on affective symptoms through hope. The hierarchical models showed that (1) hope and resilience account significantly for the variance of affective symptoms above age, sex, and life-stress; (2) Resilience Total score has greater incremental validity than positive scales of HHS Hope; and (3) RSA Total score, HHS Optimism/Spiritual support, Stressful life-events and sex are unique predictors of affective symptoms. The SEM analyses verified a stronger direct effect of resilience in the prediction of affective symptoms above the significant partial mediated effect of resilience through hope. Additionally, results show that age and better educational opportunities were associated with protection (i.e. resilience and hope) and emotional well-being (i.e. affective symptoms and hopelessness). Women showed higher scores in social competences and resources (RSA), interconnectedness and initiative to take action (HHS). However, they have poorer evaluations of own abilities and efficacy (RSA), and higher scores in all the affective symptoms assessed. The RSA has incremental validity above the HHS, however, both the RSA and the HHS are effective, differentiated and complementary measures of protection that are of high relevance for research on psychosocial and emotional well-being.

Sediments as tracers for transport and deposition processes in peri-alpine lakes: A case study

NASA Astrophysics Data System (ADS)

Righetti, Maurizio; Toffolon, Marco; Lucarelli, Corrado; Serafini, Michele

2011-12-01

SummaryThe benthic sediment fingerprint is analysed in the small peri-alpine lake Levico (Trentino, Italy) to identify the causes of recurrent phenomena of turbidity peaks, particularly evident in a littoral region of the water body. In order to study the sediment transport processes, we exploit the fact that the sediment supply from the major tributary has a specific chemical composition, which differs from that of the nearby lake basin. Three elements (Fe, Al, K) have been used as tracers to identify the source and the deposition patterns of tributary sediments, and another typical element, Si, has been critically analysed because of its dual (allochthonous and autochthonous) origin. Several samples of the benthic material have been analysed using SEM-EDS, and the results of the sedimentological characterisation have been compared with the patterns of sediment accumulation at the bed of the lake obtained using a three-dimensional numerical model, in response to the tributary supply under different external forcing and stratification conditions. The coupled use of field measurements and numerical results suggests that the turbidity phenomena are strongly related to the deposition of the sediments supplied by the tributary stream, and shows that it is possible to reconstruct the process of local transport when the tributary inflow is chemically specific.

An Analysis on the Correlation and Gender Difference between College Students' Internet Addiction and Mobile Phone Addiction in Taiwan

PubMed Central

Chiu, Su-Lin

2013-01-01

This study is aimed at constructing a correlative model between Internet addiction and mobile phone addiction; the aim is to analyse the correlation (if any) between the two traits and to discuss the influence confirming that the gender has difference on this fascinating topic; taking gender into account opens a new world of scientific study to us. The study collected 448 college students on an island as study subjects, with 61.2% males and 38.8% females. Moreover, this study issued Mobile Phone Addiction Scale and Internet Addiction Scale to conduct surveys on the participants and adopts the structural equation model (SEM) to process the collected data. According to the study result, (1) mobile phone addiction and Internet addiction are positively related; (2) female college students score higher than male ones in the aspect of mobile addiction. Lastly, this study proposes relevant suggestions to serve as a reference for schools, college students, and future studies based on the study results. PMID:25938115

Influence of some psychosocial factors on mobbing and its consequences among employees working with people with intellectual disabilities.

PubMed

Figueiredo-Ferraz, Hugo; Gil-Monte, Pedro R; Grau-Alberola, Ester; Llorca-Pellicer, Marta; García-Juesas, Juan A

2012-09-01

The problem of mobbing has attracted a great deal of attention over the past few years. This concern has increased the study of the phenomena, which has resulted in many scientific publications. Mobbing has been characterized as an emerging risk at work. The aim of this study was to analyse the influence of some psychosocial factors at work - role clarity, interpersonal conflicts and social support - on mobbing and its consequences - that is, inclination towards absenteeism and psychosomatic disorders. The sample included 422 employees working with people with intellectual disabilities. Structural equation modelling (SEM) was used to test the hypotheses. The Hypothesized model showed an adequate fit to data, and all hypothesized relationships were significant. The results of this study provide support for the mediator role of mobbing in the relationship between high role ambiguity, low social support and high interpersonal conflicts and psychosomatic disorders and inclination towards absenteeism. © 2012 Blackwell Publishing Ltd.

Understanding Eating Behaviors through Parental Communication and the Integrative Model of Behavioral Prediction.

PubMed

Scheinfeld, Emily; Shim, Minsun

2017-05-01

Emerging adulthood (EA) is an important yet overlooked period for developing long-term health behaviors. During these years, emerging adults adopt health behaviors that persist throughout life. This study applies the Integrative Model of Behavioral Prediction (IMBP) to examine the role of childhood parental communication in predicting engagement in healthful eating during EA. Participants included 239 college students, ages 18 to 25, from a large university in the southern United States. Participants were recruited and data collection occurred spring 2012. Participants responded to measures to assess perceived parental communication, eating behaviors, attitudes, subjective norms, and behavioral control over healthful eating. SEM and mediation analyses were used to address the hypotheses posited. Data demonstrated that perceived parent-child communication - specifically, its quality and target-specific content - significantly predicted emerging adults' eating behaviors, mediated through subjective norm and perceived behavioral control. This study sets the stage for further exploration and understanding of different ways parental communication influences emerging adults' healthy behavior enactment.

Negative emotions and behaviour: The role of regulatory emotional self-efficacy.

PubMed

Mesurado, Belén; Vidal, Elisabeth Malonda; Mestre, Anna Llorca

2018-04-01

The objective of this study is to test a longitudinal model that analyses the direct effect of negative emotions (anger, depression and anxiety, wave 1) on prosocial and aggressive behaviour (wave 2) in adolescents. And the indirect effect of negative emotions (wave 1) on prosocial and aggressive behaviour (wave 2) through regulatory emotional self-efficacy. Data was obtained from 417 adolescents in a two-wave longitudinal study (225 girls, M age = 14.70 years) from schools located in Valencia, Spain. SEM was employed to explore longitudinal models. The results showed that anger had a direct relationship with prosocial behaviour and aggression, measured two years later. However, the depression and anxiety states did not predict prosociality and aggressiveness. The mediation role of regulatory emotional self-efficacy between negative emotion and behaviours was only partially confirmed. Finally, only the perception of self-efficacy in expressing positive affect is related to prosociality and aggressiveness. Copyright © 2018 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

Utilization of Corn Cob and TiO2 Photocatalyst Thin Films for Dyes Removal.

PubMed

Gan, Hui-Yee; Leow, Li-Eau; Ong, Siew-Teng

2017-01-01

The effectiveness of using TiO2 and corn cob films to remove Malachite Green oxalate (MG) and Acid Yellow 17 (AY 17) from binary dye solution was studied. The immobilization method in this study can avoid the filtration step which is not suited for practical applications. Batch studies were performed under different experimental conditions and the parameters studied involved initial pH of dye solution, initial dye concentration and contact time and reusability. The equilibrium data of MG and AY 17 conform to Freundlich and Langmuir isotherm model, respectively. The percentage removal of MG remained high after four sorption cycles, however for AY 17, a greater reduction was observed. The removal of both dyes were optimized and modeled via Plackett- Burman design (PB) and Response Surface Methodology (RSM). IR spectrum and surface conditions analyses were carried out using fourier-transform infrared spectrophotometer (FTIR), scanning electron microscope (SEM) and atomic force microscope (AFM), respectively.

An Analysis on the Correlation and Gender Difference between College Students' Internet Addiction and Mobile Phone Addiction in Taiwan.

PubMed

Chiu, Shao-I; Hong, Fu-Yuan; Chiu, Su-Lin

2013-01-01

This study is aimed at constructing a correlative model between Internet addiction and mobile phone addiction; the aim is to analyse the correlation (if any) between the two traits and to discuss the influence confirming that the gender has difference on this fascinating topic; taking gender into account opens a new world of scientific study to us. The study collected 448 college students on an island as study subjects, with 61.2% males and 38.8% females. Moreover, this study issued Mobile Phone Addiction Scale and Internet Addiction Scale to conduct surveys on the participants and adopts the structural equation model (SEM) to process the collected data. According to the study result, (1) mobile phone addiction and Internet addiction are positively related; (2) female college students score higher than male ones in the aspect of mobile addiction. Lastly, this study proposes relevant suggestions to serve as a reference for schools, college students, and future studies based on the study results.

Knowledge work productivity effect on quality of knowledge work in software development process in SME

NASA Astrophysics Data System (ADS)

Yusoff, Mohd Zairol; Mahmuddin, Massudi; Ahmad, Mazida

2016-08-01

Knowledge and skill are necessary to develop the capability of knowledge workers. However, there is very little understanding of what the necessary knowledge work (KW) is, and how they influence the quality of knowledge work or knowledge work productivity (KWP) in software development process, including that in small and medium-sized (SME) enterprise. The SME constitutes a major part of the economy and it has been relatively unsuccessful in developing KWP. Accordingly, this paper seeks to explore the influencing dimensions of KWP that effect on the quality of KW in SME environment. First, based on the analysis of the existing literatures, the key characteristics of KW productivity are defined. Second, the conceptual model is proposed, which explores the dimensions of the KWP and its quality. This study analyses data collected from 150 respondents (based on [1], who involve in SME in Malaysia and validates the models by using structural equation modeling (SEM). The results provide an analysis of the effect of KWP on the quality of KW and business success, and have a significant relevance for both research and practice in the SME

Improving contact layer patterning using SEM contour based etch model

NASA Astrophysics Data System (ADS)

Weisbuch, François; Lutich, Andrey; Schatz, Jirka; Hertzsch, Tino; Moll, Hans-Peter

2016-10-01

The patterning of the contact layer is modulated by strong etch effects that are highly dependent on the geometry of the contacts. Such litho-etch biases need to be corrected to ensure a good pattern fidelity. But aggressive designs contain complex shapes that can hardly be compensated with etch bias table and are difficult to characterize with standard CD metrology. In this work we propose to implement a model based etch compensation method able to deal with any contact configuration. With the help of SEM contours, it was possible to get reliable 2D measurements particularly helpful to calibrate the etch model. The selections of calibration structures was optimized in combination with model form to achieve an overall errRMS of 3nm allowing the implementation of the model in production.

Theoretical and measured electric field distributions within an annular phased array: consideration of source antennas.

PubMed

Zhang, Y; Joines, W T; Jirtle, R L; Samulski, T V

1993-08-01

The magnitude of E-field patterns generated by an annular array prototype device has been calculated and measured. Two models were used to describe the radiating sources: a simple linear dipole and a stripline antenna model. The stripline model includes detailed geometry of the actual antennas used in the prototype and an estimate of the antenna current based on microstrip transmission line theory. This more detailed model yields better agreement with the measured field patterns, reducing the rms discrepancy by a factor of about 6 (from approximately 23 to 4%) in the central region of interest where the SEM is within 25% of the maximum. We conclude that accurate modeling of source current distributions is important for determining SEM distributions associated with such heating devices.

Predicting physical activity and fruit and vegetable intake in adolescents: a test of the information, motivation, behavioral skills model.

PubMed

Kelly, Stephanie; Melnyk, Bernadette Mazurek; Belyea, Michael

2012-04-01

Most adolescents do not meet national recommendations regarding physical activity and/or the intake of fruits and vegetables. The purpose of this study was to explore whether variables in the information, motivation, behavioral skills (IMB) model of health promotion predicted physical activity and fruit and vegetable intake in 404 adolescents from 2 high schools in the Southwest United States using structural equation modeling (SEM). The SEM models included theoretical constructs, contextual variables, and moderators. The theoretical relationships in the IMB model were confirmed and were moderated by gender and race. Interventions that incorporate cognitive-behavioral skills building may be a key factor for promoting physical activity as well as fruit and vegetable intake in adolescents. Copyright © 2012 Wiley Periodicals, Inc.

Modeling of Individual and Organizational Factors Affecting Traumatic Occupational Injuries Based on the Structural Equation Modeling: A Case Study in Large Construction Industries.

PubMed

Mohammadfam, Iraj; Soltanzadeh, Ahmad; Moghimbeigi, Abbas; Akbarzadeh, Mehdi

2016-09-01

Individual and organizational factors are the factors influencing traumatic occupational injuries. The aim of the present study was the short path analysis of the severity of occupational injuries based on individual and organizational factors. The present cross-sectional analytical study was implemented on traumatic occupational injuries within a ten-year timeframe in 13 large Iranian construction industries. Modeling and data analysis were done using the structural equation modeling (SEM) approach and the IBM SPSS AMOS statistical software version 22.0, respectively. The mean age and working experience of the injured workers were 28.03 ± 5.33 and 4.53 ± 3.82 years, respectively. The portions of construction and installation activities of traumatic occupational injuries were 64.4% and 18.1%, respectively. The SEM findings showed that the individual, organizational and accident type factors significantly were considered as effective factors on occupational injuries' severity (P < 0.05). Path analysis of occupational injuries based on the SEM reveals that individual and organizational factors and their indicator variables are very influential on the severity of traumatic occupational injuries. So, these should be considered to reduce occupational accidents' severity in large construction industries.

Are Systemic Manifestations Ascribable to COPD in Smokers? A Structural Equation Modeling Approach.

PubMed

Boyer, Laurent; Bastuji-Garin, Sylvie; Chouaid, Christos; Housset, Bruno; Le Corvoisier, Philippe; Derumeaux, Geneviève; Boczkowski, Jorge; Maitre, Bernard; Adnot, Serge; Audureau, Etienne

2018-06-05

Whether the systemic manifestations observed in Chronic Obstructive Pulmonary Disease (COPD) are ascribable to lung dysfunction or direct effects of smoking is in debate. Structural Equations Modeling (SEM), a causal-oriented statistical approach, could help unraveling the pathways involved, by enabling estimation of direct and indirect associations between variables. The objectives of the study was to investigate the relative impact of smoking and COPD on systemic manifestations, inflammation and telomere length. In 292 individuals (103 women; 97 smokers with COPD, 96 smokers without COPD, 99 non-smokers), we used SEM to explore the pathways between smoking (pack-years), lung disease (FEV 1 , K CO ), and the following parameters: arterial stiffness (aortic pulse wave velocity, PWV), bone mineral density (BMD), appendicular skeletal muscle mass (ASMM), grip strength, insulin resistance (HOMA-IR), creatinine clearance (eGFR), blood leukocyte telomere length and inflammatory markers (Luminex assay). All models were adjusted on age and gender. Latent variables were created for systemic inflammation (inflammatory markers) and musculoskeletal parameters (ASMM, grip strength, BMD). SEM showed that most effects of smoking were indirectly mediated by lung dysfunction: e.g. via FEV 1 on musculoskeletal factor, eGFR, HOMA-IR, PWV, telomere length, CRP, white blood cells count (WBC) and inflammation factor, and via K CO on musculoskeletal factor, eGFR and PWV. Direct effects of smoking were limited to CRP and WBC. Models had excellent fit. In conclusion, SEM highlighted the major role of COPD in the occurrence of systemic manifestations while smoking effects were mostly mediated by lung function.

Novel characteristics of traction force in biliary self-expandable metallic stents.

PubMed

Hori, Yasuki; Hayashi, Kazuki; Yoshida, Michihiro; Naitoh, Itaru; Ban, Tesshin; Miyabe, Katsuyuki; Kondo, Hiromu; Nishi, Yuji; Umemura, Shuichiro; Fujita, Yasuaki; Natsume, Makoto; Kato, Akihisa; Ohara, Hirotaka; Joh, Takashi

2017-05-01

In recent years, knowledge concerning the mechanical properties of self-expandable metallic stents (SEMS) has increased. In a previous study, we defined traction force and traction momentum and reported that these characteristics are important for optimal stent deployment. However, traction force and traction momentum were represented as relative values and were not evaluated in various conditions. The purpose of the present study was to measure traction force in various situations assumed during SEMS placement. Traction force and traction momentum were measured in non-stricture, stricture, and angled stricture models using in-house equipment. Stricture and angled stricture models had significantly higher traction force and traction momentum than those of the non-stricture model (stricture vs non-stricture: traction force, 7.2 N vs 1.4 N, P < 0.001; traction momentum, 237.8 Ns vs 62.3 Ns, P = 0.001; angled stricture vs non-stricture: traction force, 7.4 N vs 1.4 N, P < 0.001; traction momentum, 307.2 Ns vs 62.3 Ns, P < 0.001). Traction force was variable during SEMS placement and was categorized into five different stages, which were similar in both the stricture and angled stricture models. We measured traction force and traction momentum under simulated clinical conditions and demonstrated that strictures and the angular positioning of the stent influenced the traction force. Clinicians should be aware of the transition of the traction force and should schedule X-ray imaging during SEMS placement. © 2017 Japan Gastroenterological Endoscopy Society.

Supervised Learning Based Hypothesis Generation from Biomedical Literature.

PubMed

Sang, Shengtian; Yang, Zhihao; Li, Zongyao; Lin, Hongfei

2015-01-01

Nowadays, the amount of biomedical literatures is growing at an explosive speed, and there is much useful knowledge undiscovered in this literature. Researchers can form biomedical hypotheses through mining these works. In this paper, we propose a supervised learning based approach to generate hypotheses from biomedical literature. This approach splits the traditional processing of hypothesis generation with classic ABC model into AB model and BC model which are constructed with supervised learning method. Compared with the concept cooccurrence and grammar engineering-based approaches like SemRep, machine learning based models usually can achieve better performance in information extraction (IE) from texts. Then through combining the two models, the approach reconstructs the ABC model and generates biomedical hypotheses from literature. The experimental results on the three classic Swanson hypotheses show that our approach outperforms SemRep system.

Relationship between early language skills and the development of inattention/hyperactivity symptoms during the preschool period: Results of the EDEN mother-child cohort.

PubMed

Peyre, Hugo; Galera, Cedric; van der Waerden, Judith; Hoertel, Nicolas; Bernard, Jonathan Y; Melchior, Maria; Ramus, Franck

2016-11-08

This study aims to examine bidirectional relationships between children's language skills and Inattention/Hyperactivity (IH) symptoms during preschool. Children (N = 1459) from the EDEN mother-child cohort were assessed at ages 3 and 5.5 years. Language skills were evaluated using the WPPSI-III, NEPSY and ELOLA batteries. Children's behavior, including IH symptoms, was assessed using the parent-rated Strengths & Difficulties Questionnaire (SDQ). Using a Structural Equation Modeling (SEM) approach, we examined the relationship between language skills and IH symptoms, as well as potential mediating processes. SEM analyses indicated a small negative effect of language skills at 3 years on ADHD symptoms at 5.5 years after adjusting for IH symptoms at 3 years (β =-0.12, SE = 0.04, p-value = 0.002). Interpersonal difficulties did not mediate the relationship between early language skills and later IH symptoms, nor was this association reduced after adjusting for a broad range of pre- and postnatal environmental factors and performance IQ. Among different language skills, receptive syntax at 3 years was most strongly related to IH symptoms at 5.5 years. Poor language skills at age 3 may predict IH symptoms when a child enters primary school. Implications for the understanding and the prevention of the co-occurrence of language disorders and ADHD are discussed.

The impact of financial incentives on physician empathy: a study from the perspective of patients with private and statutory health insurance.

PubMed

Neumann, Melanie; Bensing, Jozien; Wirtz, Markus; Wübker, Ansgar; Scheffer, Christian; Tauschel, Diethard; Edelhäuser, Friedrich; Ernstmann, Nicole; Pfaff, Holger

2011-08-01

We hypothesized that patients' ratings of physician empathy (PE) would be higher among those with private health insurance (PHI, referring to financial incentive) than among patients with statutory health insurance (SHI). A postal survey was administered to 710 cancer patients. PE was assessed using the Consultation-and-Relational-Empathy measure. T-tests were conducted to analyse whether PHI and SHI-patients differ in their ratings of PE and variables relating to contact time with the physician. Structural-equation-modelling (SEM) verified mediating effects. PHI-patients rated physician empathy higher. SEM revealed that PHI-status has a strong significant effect on frequency of talking with the physician, which has a strong significant effect (1) on PE and (2) has a moderate effect on patients' perception of medical staff stress, thereby also affecting patients' ratings of PE. Our findings suggest that PHI-status is one necessary precondition for physicians spending more time with the patient. Spending more time with the PHI-patient has two major effects: it results in a more positive perception of PE and positively impacts PHI-patients' perception of medical staff stress, which in turn, again influences PE. Health policy should discuss these findings in terms of equality in receiving high-quality care. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Effects of Ag and Cu ions on the microbial corrosion of 316L stainless steel in the presence of Desulfovibrio sp.

PubMed

Unsal, Tuba; Ilhan-Sungur, Esra; Arkan, Simge; Cansever, Nurhan

2016-08-01

The utilization of Ag and Cu ions to prevent both microbial corrosion and biofilm formation has recently increased. The emphasis of this study lies on the effects of Ag and Cu ions on the microbial corrosion of 316L stainless steel (SS) induced by Desulfovibrio sp. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization were used to analyze the corrosion behavior. The biofilm formation, corrosion products and Ag and Cu ions on the surfaces were investigated using scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS) and elemental mapping. Through circuit modeling, EIS results were used to interpret the physicoelectric interactions between the electrode, biofilm and culture interfaces. EIS results indicated that the metabolic activity of Desulfovibrio sp. accelerated the corrosion rate of SS in both conditions with and without ions. However, due to the retardation in the growth of Desulfovibrio sp. in the presence of Ag and Cu ions, significant decrease in corrosion rate was observed in the culture with the ions. In addition, SEM and EIS analyses revealed that the presence of the ions leads to the formation on the SS of a biofilm with different structure and morphology. Elemental analysis with EDS detected mainly sulfide- and phosphorous-based corrosion products on the surfaces. Copyright © 2016 Elsevier B.V. All rights reserved.

Spatio-Temporal Change Modeling of Lulc: a Semantic Kriging Approach

NASA Astrophysics Data System (ADS)

Bhattacharjee, S.; Ghosh, S. K.

2015-07-01

Spatio-temporal land-use/ land-cover (LULC) change modeling is important to forecast the future LULC distribution, which may facilitate natural resource management, urban planning, etc. The spatio-temporal change in LULC trend often exhibits non-linear behavior, due to various dynamic factors, such as, human intervention (e.g., urbanization), environmental factors, etc. Hence, proper forecasting of LULC distribution should involve the study and trend modeling of historical data. Existing literatures have reported that the meteorological attributes (e.g., NDVI, LST, MSI), are semantically related to the terrain. Being influenced by the terrestrial dynamics, the temporal changes of these attributes depend on the LULC properties. Hence, incorporating meteorological knowledge into the temporal prediction process may help in developing an accurate forecasting model. This work attempts to study the change in inter-annual LULC pattern and the distribution of different meteorological attributes of a region in Kolkata (a metropolitan city in India) during the years 2000-2010 and forecast the future spread of LULC using semantic kriging (SemK) approach. A new variant of time-series SemK is proposed, namely Rev-SemKts to capture the multivariate semantic associations between different attributes. From empirical analysis, it may be observed that the augmentation of semantic knowledge in spatio-temporal modeling of meteorological attributes facilitate more precise forecasting of LULC pattern.

Assessing pollution in a Mediterranean lagoon using acid volatile sulfides and estimations of simultaneously extracted metals.

PubMed

Zaaboub, Noureddine; Helali, Mohamed Amine; Martins, Maria Virgínia Alves; Ennouri, Rym; Béjaoui, Béchir; da Silva, Eduardo Ferreira; El Bour, Monia; Aleya, Lotfi

2016-11-01

Bizerte Lagoon is a southern Mediterranean semi-enclosed lagoon with a maximum depth of 12 m. After assessing sediment quality, the authors report on the physicochemical characteristics of the lagoon's surface sediment using SEM (simultaneously extracted metals) and AVS (acid volatile sulfides) as proxies. Biogeochemical tools are used to investigate the environmental disturbance at the water-sediment interface by means of SEM and AVS to seek conclusions concerning the study area's pollution status. Results confirm accumulation of trace elements in sediment. The use of the SEM-AVS model with organic matter in sediment (ƒOC) confirms possible bioavailability of accumulated trace elements, especially Zn, in the southern part of the lagoon, with organic matter playing an important role in SEM excess correction to affirm a nontoxic total metal sediment state. Individual trace element toxicity is dependent on the bioavailable fraction of SEM Metal on sediment, as is the influence of lagoon inflow from southern water sources on element bioavailability. Appropriate management strategies are highly recommended to mitigate any potential harmful effects on health from this heavy-metal-based pollution.

Group 12 dithiocarbamate complexes: synthesis, spectral studies and their use as precursors for metal sulfides nanoparticles and nanocomposites.

PubMed

Ajibade, Peter A; Ejelonu, Benjamin C

2013-09-01

Zn(II), Cd(II) and Hg(II) dithiocarbamate complexes have been synthesized and characterized by elemental analysis, thermogravimetric analysis, UV-Vis, FTIR, (1)H- and (13)C NMR spectroscopy. The complexes were thermolysed at 180 °C and used as single molecule precursors for the synthesis of HDA capped ZnS, CdS and HgS nanoparticles and polymethylmethacrylate (PMMA) nanocomposites. The optical and structural properties of the nanoparticles and nanocomposites were studied by UV-Vis, PL, XRD and SEM. The crystallites sizes of the nanoparticles varied between 3.03 and 23.45 nm. SEM and EDX analyses of the nanocomposites confirmed the presence of the nanoparticles in the polymer matrix. Copyright © 2013 Elsevier B.V. All rights reserved.

Synthesis and Thermal and Photo Behaviors of New Polyamide/Organocaly Nanocomposites Containing Para Phenylenediacrylic Moiety

NASA Astrophysics Data System (ADS)

Faghihi, Khalil; Soleimani, Masoumeh; Shabanian, Meisam; Abootalebi, Ashraf Sadat

2011-06-01

New type of aromatic polyamide/montmorillonite nanocomposites were produced using solution process in N-methyl-2-pyrolidone. Amide chains were synthesized from 4,4'-diaminodiphenyl sulfone and p-phenylenediacrylic acid in N-methyl-2-pyrolidone. The resulting nanocomposite films containing 5-15 mass % of organoclay were characterized for FT-IR, scanning electronmicroscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), optical transparency and water absorption measurements. The distribution of organoclay and nanostructure of the composites were investigated by (XRD) and SEM analyses. Thermogravimetric analysis indicated an increase in thermal stability of nanocomposites as compared to pristine polyamide. The percentage optical transparency and water absorption of these hybrids was found to be much reduced upon the addition of modified layered silicate indicating decreased permeability.

School Emphasis on Academic Success: Exploring Changes in Science Performance in Norway between 2007 and 2011 Employing Two-Level SEM

ERIC Educational Resources Information Center

Nilsen, Trude; Gustafsson, Jan-Eric

2014-01-01

We study whether changes in school emphasis on academic success (SEAS) and safe schools (SAFE) may explain the increased science performance in Norway between TIMSS 2007 and 2011. Two-level structural equation modelling (SEM) of merged TIMSS data was used to investigate whether changes in levels of SEAS and SAFE mediate the changes in science…

Construction of a Virtual Scanning Electron Microscope (VSEM)

NASA Technical Reports Server (NTRS)

Fried, Glenn; Grosser, Benjamin

2004-01-01

The Imaging Technology Group (ITG) proposed to develop a Virtual SEM (VSEM) application and supporting materials as the first installed instrument in NASA s Virtual Laboratory Project. The instrument was to be a simulator modeled after an existing SEM, and was to mimic that real instrument as closely as possible. Virtual samples would be developed and provided along with the instrument, which would be written in Java.

Resveratrol given intraperitoneally does not inhibit growth of high-risk t(4;11) acute lymphoblastic leukemia cells in NOD/SCID mouse model

USDA-ARS?s Scientific Manuscript database

The efficacy of the phytochemical resveratrol as a preventive agent against the growth of t(4;11) acute lymphoblastic leukemia (ALL) was evaluated in NOD.CB17-Prkdcscid/J mice engrafted with the human t(4;11) ALL line SEM. SEM cells were injected into the tail vein and engraftment was monitored by ...

Is the ML Chi-Square Ever Robust to Nonnormality? A Cautionary Note with Missing Data

ERIC Educational Resources Information Center

Savalei, Victoria

2008-01-01

Normal theory maximum likelihood (ML) is by far the most popular estimation and testing method used in structural equation modeling (SEM), and it is the default in most SEM programs. Even though this approach assumes multivariate normality of the data, its use can be justified on the grounds that it is fairly robust to the violations of the…

Dry Snow Metamorphism

DTIC Science & Technology

2012-09-19

behavior of snow during metamorphism and grain sintering using mathematical models. 2 Approach Our approach involved the collection and...examination of both types of specimens at various stages of metamorphism using the SEM and micro-CT. More specifically, the above approach involved...than 10ºC·m-1). 5. High-resolution images and X-ray spectra of snow specimens at various metamorphism stages were obtained using an SEM and EDS. 6

Generalized Multilevel Structural Equation Modeling

ERIC Educational Resources Information Center

Rabe-Hesketh, Sophia; Skrondal, Anders; Pickles, Andrew

2004-01-01

A unifying framework for generalized multilevel structural equation modeling is introduced. The models in the framework, called generalized linear latent and mixed models (GLLAMM), combine features of generalized linear mixed models (GLMM) and structural equation models (SEM) and consist of a response model and a structural model for the latent…

Mechanical Sensing with Flexible Metallic Nanowires

NASA Astrophysics Data System (ADS)

Dobrokhotov, Vladimir; Yazdanpanah, Mehdi; Pabba, Santosh; Safir, Abdelilah; Cohn, Robert

2008-03-01

A calibrated method of force sensing is demonstrated in which the buckled shape of a long flexible metallic nanowire is interpreted to determine the applied force. Using a nanomanipulator the nanowire is buckled in the chamber of a scanning electron microscope (SEM) and the buckled shapes are recorded in SEM images. Force is determined as a function of deflection for an assumed elastic modulus by fitting the shapes using the generalized elastica model. In this calibration the elastic modulus was determined using an auxiliary AFM measurement, with the needle in the same orientation as in the SEM. Following this calibration the needle was used as a sensor in a different orientation than the AFM coordinates to deflect a suspended PLLA polymer fiber from which the elastic modulus (2.96 GPa) was determined. In this study the same needle remained rigidly secured to the AFM cantilever throughout the entire SEM/AFM calibration procedure and the characterization of the nanofiber.

Plasmonic resonances in ordered and disordered aluminum nanocavities arrays.

NASA Astrophysics Data System (ADS)

Campuzano, R. G.; Mendoza, D.

2017-01-01

Nanocavities arrays were synthesized by electrochemical anodization of aluminum using oxalic and phosphoric acids as electrolytes. The morphology and topography of these structures were evaluated by SEM and AFM. Plasmonic properties of Al cavities arrays with different ordering and dimensions were analysed based on specular reflectivity. Al cavities arrays fabricated with phosphoric acid dramatically reduced the optical reflectivity as compared with unstructured Al. At the same time pronounced reflectivity dips were detectable in the 300nm-400nm range, which were ascribed to (0,1) plasmonic mode, and also a colored appearance in the samples is noticeably depending on the observation angle. These changes are not observed in samples made with oxalic acid and this fact was explained, based on a theoretical model, in terms that the surface plasmons are excited far in the UV range.

Dataset on brand culture and perceived value of offerings to customers in the hospitality industry in Nigeria.

PubMed

Dirisu, Joy; Worlu, Rowland; Osibanjo, Adewale; Borisade, Taiye; Olokundun, Maxwell; Atolagbe, Tolu; Obi, James

2018-08-01

This study critically examines the role of brand culture in influencing the perceived value of offerings to customers within the hospitality industry in Nigeria. In today's competitive market, the extent at which organizations disregard the importance of developing a strong brand culture before communicating their value to the outside world has become worrisome. Hence, this study filled in the gaps and a total of 434 customers drawn from six different hotels in Lagos state, Nigeria, were sampled. The data were analysed using Structural Equation Modelling (SEM). Management of these hotels were able to define their expectations in order to deliver a consistent brand experience to their customers. The result showed that brand culture has positive significant influence on the perceived value of offerings to customers. Important recommendations have also been made.

In first-time mothers, post-partum depressive symptom prospectively predict symptoms of post-traumatic stress.

PubMed

Shahar, Golan; Herishanu-Gilutz, Shirley; Holcberg, Gershon; Kofman, Ora

2015-11-01

Symptoms of both depression and Post-Traumatic Stress Disorder (PTSD) are prevalent among first-time mothers following birth. However, the direction of the association between the two types of symptoms is unclear. Ninety six first-time mothers giving birth via vaginal delivery (N=38), emergency C-Section (N=27) and planned C-Section (N=21) were assessed for depression and PTSD twice: Six weeks post-partum and six-weeks later. Cross-lagged Structural Equation Modeling (SEM) analyses revealed a prospective effect of depressive symptoms on PTSD symptoms. No moderating factors were identified. A relatively modest sample size and only two assessment waves. An early detection and intervention with symptoms of post-partum depression might also prevent the development of PTSD symptoms. Copyright © 2015 Elsevier B.V. All rights reserved.

Structural equation modeling of the inflammatory response to traffic air pollution

PubMed Central

Baja, Emmanuel S.; Schwartz, Joel D.; Coull, Brent A.; Wellenius, Gregory A.; Vokonas, Pantel S.; Suh, Helen H.

2015-01-01

Several epidemiological studies have reported conflicting results on the effect of traffic-related pollutants on markers of inflammation. In a Bayesian framework, we examined the effect of traffic pollution on inflammation using structural equation models (SEMs). We studied measurements of C-reactive protein (CRP), soluble vascular cell adhesion molecule-1 (sVCAM-1), and soluble intracellular adhesion molecule-1 (sICAM-1) for 749 elderly men from the Normative Aging Study. Using repeated measures SEMs, we fit a latent variable for traffic pollution that is reflected by levels of black carbon, carbon monoxide, nitrogen monoxide and nitrogen dioxide to estimate its effect on a latent variable for inflammation that included sICAM-1, sVCAM-1 and CRP. Exposure periods were assessed using 1-, 2-, 3-, 7-, 14- and 30-day moving averages previsit. We compared our findings using SEMs with those obtained using linear mixed models. Traffic pollution was related to increased inflammation for 3-, 7-, 14- and 30-day exposure periods. An inter-quartile range increase in traffic pollution was associated with a 2.3% (95% posterior interval (PI): 0.0–4.7%) increase in inflammation for the 3-day moving average, with the most significant association observed for the 30-day moving average (23.9%; 95% PI: 13.9–36.7%). Traffic pollution adversely impacts inflammation in the elderly. SEMs in a Bayesian framework can comprehensively incorporate multiple pollutants and health outcomes simultaneously in air pollution–cardiovascular epidemiological studies. PMID:23232970

Methodological Issues in Examining Measurement Equivalence in Patient Reported Outcomes Measures: Methods Overview to the Two-Part Series, “Measurement Equivalence of the Patient Reported Outcomes Measurement Information System® (PROMIS®) Short Forms”

PubMed Central

Teresi, Jeanne A.; Jones, Richard N.

2017-01-01

The purpose of this article is to introduce the methods used and challenges confronted by the authors of this two-part series of articles describing the results of analyses of measurement equivalence of the short form scales from the Patient Reported Outcomes Measurement Information System® (PROMIS®). Qualitative and quantitative approaches used to examine differential item functioning (DIF) are reviewed briefly. Qualitative methods focused on generation of DIF hypotheses. The basic quantitative approaches used all rely on a latent variable model, and examine parameters either derived directly from item response theory (IRT) or from structural equation models (SEM). A key methods focus of these articles is to describe state-of-the art approaches to examination of measurement equivalence in eight domains: physical health, pain, fatigue, sleep, depression, anxiety, cognition, and social function. These articles represent the first time that DIF has been examined systematically in the PROMIS short form measures, particularly among ethnically diverse groups. This is also the first set of analyses to examine the performance of PROMIS short forms in patients with cancer. Latent variable model state-of-the-art methods for examining measurement equivalence are introduced briefly in this paper to orient readers to the approaches adopted in this set of papers. Several methodological challenges underlying (DIF-free) anchor item selection and model assumption violations are presented as a backdrop for the articles in this two-part series on measurement equivalence of PROMIS measures. PMID:28983448

Methodological Issues in Examining Measurement Equivalence in Patient Reported Outcomes Measures: Methods Overview to the Two-Part Series, "Measurement Equivalence of the Patient Reported Outcomes Measurement Information System® (PROMIS®) Short Forms".

PubMed

Teresi, Jeanne A; Jones, Richard N

2016-01-01

The purpose of this article is to introduce the methods used and challenges confronted by the authors of this two-part series of articles describing the results of analyses of measurement equivalence of the short form scales from the Patient Reported Outcomes Measurement Information System ® (PROMIS ® ). Qualitative and quantitative approaches used to examine differential item functioning (DIF) are reviewed briefly. Qualitative methods focused on generation of DIF hypotheses. The basic quantitative approaches used all rely on a latent variable model, and examine parameters either derived directly from item response theory (IRT) or from structural equation models (SEM). A key methods focus of these articles is to describe state-of-the art approaches to examination of measurement equivalence in eight domains: physical health, pain, fatigue, sleep, depression, anxiety, cognition, and social function. These articles represent the first time that DIF has been examined systematically in the PROMIS short form measures, particularly among ethnically diverse groups. This is also the first set of analyses to examine the performance of PROMIS short forms in patients with cancer. Latent variable model state-of-the-art methods for examining measurement equivalence are introduced briefly in this paper to orient readers to the approaches adopted in this set of papers. Several methodological challenges underlying (DIF-free) anchor item selection and model assumption violations are presented as a backdrop for the articles in this two-part series on measurement equivalence of PROMIS measures.

Learner Centered Experiences with Flipped Classroom and Mobile Online Webinars in Distance Higher Education Program

ERIC Educational Resources Information Center

Amhag, Lisbeth

2015-01-01

The aim of this study is to describe and analyse students' learning activities in distance higher education program with online webinars (WEB-based semINAR) by computer, laptop or mobile app for phones and tablets directly face-to-face (F2F) with other students and teachers introduced by "flipped classroom." The data collection consists…

Processing and performance of self-healing materials

NASA Astrophysics Data System (ADS)

Tan, P. S.; Zhang, M. Q.; Bhattacharyya, D.

2009-08-01

Two self-healing methods were implemented into composite materials with self-healing capabilities, using hollow glass fibres (HGF) and microencapsulated epoxy resin with mercaptan as the hardener. For the HGF approach, two perpendicular layers of HGF were put into an E-glass/epoxy composite, and were filled with coloured epoxy resin and hardener. The HGF samples had a novel ball indentation test method done on them. The samples were analysed using micro-CT scanning, confocal microscopy and penetrant dye. Micro-CT and confocal microscopy produced limited success, but their viability was established. Penetrant dye images showed resin obstructing flow of dye through damage regions, suggesting infiltration of resin into cracks. Three-point bend tests showed that overall performance could be affected by the flaws arising from embedding HGF in the material. For the microcapsule approach, samples were prepared for novel double-torsion tests used to generate large cracks. The samples were compared with pure resin samples by analysing them using photoelastic imaging and scanning electron microscope (SEM) on crack surfaces. Photoelastic imaging established the consolidation of cracks while SEM showed a wide spread of microcapsules with their distribution being affected by gravity. Further double-torsion testing showed that healing recovered approximately 24% of material strength.

Ultrasonic-assisted synthesis of nano lead(II) coordination polymer as precursors for preparation of lead(II) oxide nano-structures: Thermal, optical properties and XRD studies.

PubMed

Ghavidelaghdam, Elham; Shahverdizadeh, Gholam Hossein; Motameni Tabatabai, Javad; Mirtamizdoust, Babak

2018-04-01

Nano structure of a lead (II) coordination polymer [Pb 2 (C 2 Cl 3 O 2 ) 2 (NO 3 ) 2 (C l2 H 8 N 2 ) 2 ] n (1), has been synthesized by a sonochemical method in different concentrations. The nano particles were characterized by scanning electron microscopy (SEM) X-ray powder diffraction (XRD), FT-IR spectroscopy and elemental analyses. The thermal stability of nano structure is closely investigated via thermal gravimetric (TGA), and compared with crystalline structure. The compounds are then heated to 600 °C to produce PbO nano particles. The resulting PbO is characterized through XRD and SEM analyses. Concentration of initial reagents effects on size and morphology of nano-structured compound 1 have been studied and show that low concentrations of initial reagents decreased particles size and leaded to uniform nano particles morphology. The photoluminescence properties of the prepared compound, as crystalline and as nanoparticles, have been investigated. The result showed a good correlation between the size and emission wavelength. Copyright © 2017. Published by Elsevier B.V.

Advanced metrology by offline SEM data processing

NASA Astrophysics Data System (ADS)

Lakcher, Amine; Schneider, Loïc.; Le-Gratiet, Bertrand; Ducoté, Julien; Farys, Vincent; Besacier, Maxime

2017-06-01

Today's technology nodes contain more and more complex designs bringing increasing challenges to chip manufacturing process steps. It is necessary to have an efficient metrology to assess process variability of these complex patterns and thus extract relevant data to generate process aware design rules and to improve OPC models. Today process variability is mostly addressed through the analysis of in-line monitoring features which are often designed to support robust measurements and as a consequence are not always very representative of critical design rules. CD-SEM is the main CD metrology technique used in chip manufacturing process but it is challenged when it comes to measure metrics like tip to tip, tip to line, areas or necking in high quantity and with robustness. CD-SEM images contain a lot of information that is not always used in metrology. Suppliers have provided tools that allow engineers to extract the SEM contours of their features and to convert them into a GDS. Contours can be seen as the signature of the shape as it contains all the dimensional data. Thus the methodology is to use the CD-SEM to take high quality images then generate SEM contours and create a data base out of them. Contours are used to feed an offline metrology tool that will process them to extract different metrics. It was shown in two previous papers that it is possible to perform complex measurements on hotspots at different process steps (lithography, etch, copper CMP) by using SEM contours with an in-house offline metrology tool. In the current paper, the methodology presented previously will be expanded to improve its robustness and combined with the use of phylogeny to classify the SEM images according to their geometrical proximities.

Modeling of electron-specimen interaction in scanning electron microscope for e-beam metrology and inspection: challenges and perspectives

NASA Astrophysics Data System (ADS)

Suzuki, Makoto; Kameda, Toshimasa; Doi, Ayumi; Borisov, Sergey; Babin, Sergey

2018-03-01

The interpretation of scanning electron microscopy (SEM) images of the latest semiconductor devices is not intuitive and requires comparison with computed images based on theoretical modeling and simulations. For quantitative image prediction and geometrical reconstruction of the specimen structure, the accuracy of the physical model is essential. In this paper, we review the current models of electron-solid interaction and discuss their accuracy. We perform the comparison of the simulated results with our experiments of SEM overlay of under-layer, grain imaging of copper interconnect, and hole bottom visualization by angular selective detectors, and show that our model well reproduces the experimental results. Remaining issues for quantitative simulation are also discussed, including the accuracy of the charge dynamics, treatment of beam skirt, and explosive increase in computing time.

Spectral element modelling of fault-plane reflections arising from fluid pressure distributions

USGS Publications Warehouse

Haney, M.; Snieder, R.; Ampuero, J.-P.; Hofmann, R.

2007-01-01

The presence of fault-plane reflections in seismic images, besides indicating the locations of faults, offers a possible source of information on the properties of these poorly understood zones. To better understand the physical mechanism giving rise to fault-plane reflections in compacting sedimentary basins, we numerically model the full elastic wavefield via the spectral element method (SEM) for several different fault models. Using well log data from the South Eugene Island field, offshore Louisiana, we derive empirical relationships between the elastic parameters (e.g. P-wave velocity and density) and the effective-stress along both normal compaction and unloading paths. These empirical relationships guide the numerical modelling and allow the investigation of how differences in fluid pressure modify the elastic wavefield. We choose to simulate the elastic wave equation via SEM since irregular model geometries can be accommodated and slip boundary conditions at an interface, such as a fault or fracture, are implemented naturally. The method we employ for including a slip interface retains the desirable qualities of SEM in that it is explicit in time and, therefore, does not require the inversion of a large matrix. We performa complete numerical study by forward modelling seismic shot gathers over a faulted earth model using SEM followed by seismic processing of the simulated data. With this procedure, we construct post-stack time-migrated images of the kind that are routinely interpreted in the seismic exploration industry. We dip filter the seismic images to highlight the fault-plane reflections prior to making amplitude maps along the fault plane. With these amplitude maps, we compare the reflectivity from the different fault models to diagnose which physical mechanism contributes most to observed fault reflectivity. To lend physical meaning to the properties of a locally weak fault zone characterized as a slip interface, we propose an equivalent-layer model under the assumption of weak scattering. This allows us to use the empirical relationships between density, velocity and effective stress from the South Eugene Island field to relate a slip interface to an amount of excess pore-pressure in a fault zone. ?? 2007 The Authors Journal compilation ?? 2007 RAS.

A guide to analysis and reconstruction of serial block face scanning electron microscopy data

PubMed Central

TAGGART, M.; RIND, F.C.; WHITE, K.

2018-01-01

Summary Serial block face scanning electron microscopy (SBF‐SEM) is a relatively new technique that allows the acquisition of serially sectioned, imaged and digitally aligned ultrastructural data. There is a wealth of information that can be obtained from the resulting image stacks but this presents a new challenge for researchers – how to computationally analyse and make best use of the large datasets produced. One approach is to reconstruct structures and features of interest in 3D. However, the software programmes can appear overwhelming, time‐consuming and not intuitive for those new to image analysis. There are a limited number of published articles that provide sufficient detail on how to do this type of reconstruction. Therefore, the aim of this paper is to provide a detailed step‐by‐step protocol, accompanied by tutorial videos, for several types of analysis programmes that can be used on raw SBF‐SEM data, although there are more options available than can be covered here. To showcase the programmes, datasets of skeletal muscle from foetal and adult guinea pigs are initially used with procedures subsequently applied to guinea pig cardiac tissue and locust brain. The tissue is processed using the heavy metal protocol developed specifically for SBF‐SEM. Trimmed resin blocks are placed into a Zeiss Sigma SEM incorporating the Gatan 3View and the resulting image stacks are analysed in three different programmes, Fiji, Amira and MIB, using a range of tools available for segmentation. The results from the image analysis comparison show that the analysis tools are often more suited to a particular type of structure. For example, larger structures, such as nuclei and cells, can be segmented using interpolation, which speeds up analysis; single contrast structures, such as the nucleolus, can be segmented using the contrast‐based thresholding tools. Knowing the nature of the tissue and its specific structures (complexity, contrast, if there are distinct membranes, size) will help to determine the best method for reconstruction and thus maximize informative output from valuable tissue. PMID:29333754

A guide to analysis and reconstruction of serial block face scanning electron microscopy data.

PubMed

Cocks, E; Taggart, M; Rind, F C; White, K

2018-05-01

Serial block face scanning electron microscopy (SBF-SEM) is a relatively new technique that allows the acquisition of serially sectioned, imaged and digitally aligned ultrastructural data. There is a wealth of information that can be obtained from the resulting image stacks but this presents a new challenge for researchers - how to computationally analyse and make best use of the large datasets produced. One approach is to reconstruct structures and features of interest in 3D. However, the software programmes can appear overwhelming, time-consuming and not intuitive for those new to image analysis. There are a limited number of published articles that provide sufficient detail on how to do this type of reconstruction. Therefore, the aim of this paper is to provide a detailed step-by-step protocol, accompanied by tutorial videos, for several types of analysis programmes that can be used on raw SBF-SEM data, although there are more options available than can be covered here. To showcase the programmes, datasets of skeletal muscle from foetal and adult guinea pigs are initially used with procedures subsequently applied to guinea pig cardiac tissue and locust brain. The tissue is processed using the heavy metal protocol developed specifically for SBF-SEM. Trimmed resin blocks are placed into a Zeiss Sigma SEM incorporating the Gatan 3View and the resulting image stacks are analysed in three different programmes, Fiji, Amira and MIB, using a range of tools available for segmentation. The results from the image analysis comparison show that the analysis tools are often more suited to a particular type of structure. For example, larger structures, such as nuclei and cells, can be segmented using interpolation, which speeds up analysis; single contrast structures, such as the nucleolus, can be segmented using the contrast-based thresholding tools. Knowing the nature of the tissue and its specific structures (complexity, contrast, if there are distinct membranes, size) will help to determine the best method for reconstruction and thus maximize informative output from valuable tissue. © 2018 The Authors. Journal of Microscopy published by John Wiley & Sons Ltd on behalf of Royal Microscopical Society.

Oral or parenteral administration of curcumin does not prevent the growth of high-risk t(4;11) acute lymphoblastic leukemia cells engrafted into a NOD/SCID mouse model

USDA-ARS?s Scientific Manuscript database

The efficacy of orally and parenterally administered curcumin was evaluated in NOD.CB17-Prkdcscid/J mice engrafted with the human t(4;11) acute lymphoblastic leukemia line SEM. SEM cells were injected into the tail vein and engraftment was monitored by flow cytometry. Once engraftment was observed...

Simulation of High-Latitude Hydrological Processes in the Torne-Kalix Basin: PILPS Phase 2(e). 3; Equivalent Model Representation and Sensitivity Experiments

NASA Technical Reports Server (NTRS)

Bowling, Laura C.; Lettenmaier, Dennis P.; Nijssen, Bart; Polcher, Jan; Koster, Randal D.; Lohmann, Dag; Houser, Paul R. (Technical Monitor)

2002-01-01

The Project for Intercomparison of Land Surface Parameterization Schemes (PILPS) Phase 2(e) showed that in cold regions the annual runoff production in Land Surface Schemes (LSSs) is closely related to the maximum snow accumulation, which in turn is controlled in large part by winter sublimation. To help further explain the relationship between snow cover, turbulent exchanges and runoff production, a simple equivalent model-(SEM) was devised to reproduce the seasonal and annual fluxes simulated by 13 LSSs that participated in PILPS Phase 2(e). The design of the SEM relates the annual partitioning of precipitation and energy in the LSSs to three primary parameters: snow albedo, effective aerodynamic resistance and evaporation efficiency. Isolation of each of the parameters showed that the annual runoff production was most sensitive to the aerodynamic resistance. The SEM was somewhat successful in reproducing the observed LSS response to a decrease in shortwave radiation and changes in wind speed forcings. SEM parameters derived from the reduced shortwave forcings suggested that increased winter stability suppressed turbulent heat fluxes over snow. Because winter sensible heat fluxes were largely negative, reductions in winter shortwave radiation imply an increase in annual average sensible heat.

GPU accelerated Monte-Carlo simulation of SEM images for metrology

NASA Astrophysics Data System (ADS)

Verduin, T.; Lokhorst, S. R.; Hagen, C. W.

2016-03-01

In this work we address the computation times of numerical studies in dimensional metrology. In particular, full Monte-Carlo simulation programs for scanning electron microscopy (SEM) image acquisition are known to be notoriously slow. Our quest in reducing the computation time of SEM image simulation has led us to investigate the use of graphics processing units (GPUs) for metrology. We have succeeded in creating a full Monte-Carlo simulation program for SEM images, which runs entirely on a GPU. The physical scattering models of this GPU simulator are identical to a previous CPU-based simulator, which includes the dielectric function model for inelastic scattering and also refinements for low-voltage SEM applications. As a case study for the performance, we considered the simulated exposure of a complex feature: an isolated silicon line with rough sidewalls located on a at silicon substrate. The surface of the rough feature is decomposed into 408 012 triangles. We have used an exposure dose of 6 mC/cm2, which corresponds to 6 553 600 primary electrons on average (Poisson distributed). We repeat the simulation for various primary electron energies, 300 eV, 500 eV, 800 eV, 1 keV, 3 keV and 5 keV. At first we run the simulation on a GeForce GTX480 from NVIDIA. The very same simulation is duplicated on our CPU-based program, for which we have used an Intel Xeon X5650. Apart from statistics in the simulation, no difference is found between the CPU and GPU simulated results. The GTX480 generates the images (depending on the primary electron energy) 350 to 425 times faster than a single threaded Intel X5650 CPU. Although this is a tremendous speedup, we actually have not reached the maximum throughput because of the limited amount of available memory on the GTX480. Nevertheless, the speedup enables the fast acquisition of simulated SEM images for metrology. We now have the potential to investigate case studies in CD-SEM metrology, which otherwise would take unreasonable amounts of computation time.

An integrated analysis of the effects of past land use on forest herb colonization at the landscape scale

USGS Publications Warehouse

Verheyen, K.; Guntenspergen, Glenn R.; Biesbrouck, B.; Hermy, M.

2003-01-01

A framework that summarizes the direct and indirect effects of past land use on forest herb recolonization is proposed, and used to analyse the colonization patterns of forest understorey herbaceous species in a 360-ha mixed forest, grassland and arable landscape in the Dijle river valley (central Belgium).Fine-scale distribution maps were constructed for 14 species. The species were mapped in 15 946 forest plots and outside forests (along parcel margins) in 5188 plots. Forest stands varied in age between 1 and more than 224 years. Detailed land-use history data were combined with the species distribution maps to identify species-specific colonization sources and to calculate colonization distances.The six most frequent species were selected for more detailed statistical analysis.Logistic regression models indicated that species frequency in forest parcels was a function of secondary forest age, distance from the nearest colonization source and their interaction. Similar age and distance effects were found within hedgerows.In 199 forest stands, data about soils, canopy structure and the cover of competitive species were collected. The relative importance of habitat quality and spatio-temporal isolation for the colonization of the forest herb species was quantified using structural equation modelling (SEM), within the framework proposed for the effects of past land use.The results of the SEM indicate that, except for the better colonizing species, the measured habitat quality variables are of minor importance in explaining colonization patterns, compared with the combination of secondary forest age and distance from colonization sources.Our results suggest the existence of a two-stage colonization process in which diaspore availability determines the initial pattern, which is affected by environmental sorting at later stages.

Racial and ethnic minority college students' stigma associated with seeking psychological help: Examining psychocultural correlates.

PubMed

Cheng, Hsiu-Lan; Kwan, Kwong-Liem Karl; Sevig, Todd

2013-01-01

Many college students underuse professional psychological help for mental health difficulties. The stigma associated with seeking such help appears to be one of the reasons for this underuse. Levels of psychological distress and past use of counseling/psychotherapy have been found to be important correlates of stigma associated with seeking psychological help (Obasi & Leong, 2009; Vogel, Wade, & Haake, 2006). For racial and ethnic minorities, the hindering effects of self-stigma and perceived stigmatization by others on treatment seeking may further be compounded by their relationships with their own ethnic groups, with other ethnic groups, and with the dominant society. This study used structural equation modeling (SEM) to test a model that explored the effects of psychological distress and psychocultural variables (i.e., ethnic identity, other-group orientation, perceived discrimination) on perceived stigmatization by others and self-stigma for seeking psychological help, controlling for past use of counseling/psychotherapy. The sample consisted of 260 African American, 166 Asian American, and 183 Latino American students. SEM multigroup analyses indicated measurement invariance, but partial structural invariance, across racial/ethnic groups. Across all 3 groups, higher levels of psychological distress and perceived racial/ethnic discrimination, respectively, predicted higher levels of perceived stigmatization by others for seeking psychological help, which, in turn, predicted greater self-stigma for seeking psychological help. Higher levels of other-group orientation predicted lower levels of self-stigma of seeking psychological help across groups. Higher levels of ethnic identity predicted lower levels of self-stigma of seeking psychological help only for African Americans. Implications for research and practice are discussed. PsycINFO Database Record (c) 2013 APA, all rights reserved.

Role of allostatic load and health behaviours in explaining socioeconomic disparities in mortality: a structural equation modelling approach.

PubMed

Kim, Gyu Ri; Jee, Sun Ha; Pikhart, Hynek

2018-06-01

The relationship between socioeconomic status and mortality has been well established; however, the extent to which biological factors mediate this relationship is less clear, and empirical evidence from non-Western settings is limited. Allostasis, a cumulative measure of physiological dysregulation, has been proposed as the underlying mechanism linking socioeconomic status to adverse health outcomes. The current study aimed to ascertain the contribution of allostatic load (AL) and health behaviours to socioeconomic inequalities in mortality among Korean adults. The sample comprised 70 713 middle-aged and older-aged adults, aged 40-79 years from the Korean Metabolic Syndrome Mortality Study. Using structural equation modelling (SEM), mediation analyses were performed to estimate the effects of socioeconomic position (SEP) on mortality over the follow-up and the extent to which AL, physical exercise and non-smoking status mediate the association between SEP and mortality. A total of 5618 deaths (7.9%) occurred during the mean follow-up of 15.2 years (SD 2.9). SEM confirmed a direct significant effect of SEP on mortality, as well as significant indirect paths through AL, physical exercise and non-smoking status. Our findings provide support for the mediating role of AL and health behaviours in the link between SEP and mortality. Policies designed to reduce social disparities in mortality in the long term should primarily focus on reducing stress and promoting healthy lifestyles among the socially disadvantaged groups. Future studies should further assess the role of other mediators such as psychosocial factors, which may contribute to socioeconomic inequalities in mortality. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Grape seed proanthocyanidins increase collagen biodegradation resistance in the dentin/adhesive interface when included in an adhesive.

PubMed

Green, Bradley; Yao, Xiaomei; Ganguly, Arindam; Xu, Changqi; Dusevich, Vladimir; Walker, Mary P; Wang, Yong

2010-11-01

Contemporary methods of dentin bonding could create hybrid layers (HLs) containing voids and exposed, demineralised collagen fibres. Proanthocyanidins (PA) have been shown to cross-link and strengthen demineralised dentin collagen, but their effects on collagen degradation within the HL have not been widely studied. The purpose of this study was to compare the morphological differences of HLs created by BisGMA/HEMA model adhesives with and without the addition of grape seed extract PA under conditions of enzymatic collagen degradation. Model adhesives formulated with and without 5% PA were bonded to the acid etched dentin. 5-μm-thick sections cut from the bonded specimens were stained with Goldner's trichrome. The specimens were then exposed to 0.1% collagenase solution for 0, 1, or 6 days. Following collagenase treatment, the specimens were analysed with SEM/TEM. Staining did not reveal a difference in the HLs created with the two adhesives. SEM showed the presence of intact collagen fibrils in all collagenase treatment conditions for specimens bonded with adhesive containing PA. These integral collagen fibrils were not observed in the specimens bonded with adhesive without PA after the same collagenase treatment. TEM confirmed that the specimens containing PA still showed normal collagen fibril organisation and dimensions after treatment with collagenase solution. In contrast, disorganised collagen fibrils in the interfacial zone lacked the typical cross-banding of normal collagen after collagenase treatment for specimens without PA. The presence of grape seed extract PA in dental adhesives may inhibit the biodegradation of unprotected collagen fibrils within the HL. Copyright © 2010 Elsevier Ltd. All rights reserved.

Modified multiblock partial least squares path modeling algorithm with backpropagation neural networks approach

NASA Astrophysics Data System (ADS)

Yuniarto, Budi; Kurniawan, Robert

2017-03-01

PLS Path Modeling (PLS-PM) is different from covariance based SEM, where PLS-PM use an approach based on variance or component, therefore, PLS-PM is also known as a component based SEM. Multiblock Partial Least Squares (MBPLS) is a method in PLS regression which can be used in PLS Path Modeling which known as Multiblock PLS Path Modeling (MBPLS-PM). This method uses an iterative procedure in its algorithm. This research aims to modify MBPLS-PM with Back Propagation Neural Network approach. The result is MBPLS-PM algorithm can be modified using the Back Propagation Neural Network approach to replace the iterative process in backward and forward step to get the matrix t and the matrix u in the algorithm. By modifying the MBPLS-PM algorithm using Back Propagation Neural Network approach, the model parameters obtained are relatively not significantly different compared to model parameters obtained by original MBPLS-PM algorithm.

Composition and microstructure of MTA and Aureoseal Plus: XRF, EDS, XRD and FESEM evaluation.

PubMed

Cianconi, L; Palopoli, P; Campanella, V; Mancini, M

2016-12-01

The aim of this study was to determine the chemical composition and the phases' microstructure of Aureoseal Plus (OGNA, Italy) and ProRoot MTA (Dentsply Tulsa Dental, USA) and to compare their characteristics. Study Design: Comparing Aureoseal Plus and ProRoot MTA microstructure by means of several analyses type. The chemical analysis of the two cements was assessed following the UNI EN ISO 196-2 norm. X-Ray fluorescence (XRF) was used to determine the element composition. The crystalline structure was analysed quantitatively using x-ray diffraction (XRD). Powders morphology was evaluated using a scanning electron microscope (SEM) with backscattering detectors, and a field emission scanning electron microscope (FESEM). Elemental analysis was performed by energy dispersive x-ray analysis (EDS). The semi-quantitative XRF analysis showed the presence of heavy metal oxides in both cements. The XRD spectra of the two cements reported the presence of dicalcium silicate, tricalcium silicate, tricalcium aluminate, tetracalcium aluminoferrite, bismuth oxide and gypsum. SEM analysis showed that ProRoot MTA powder is less coarse and more homogeneous than Aureoseal. Both powders are formed by particles of different shapes: round, prismatic and oblong. The EDS analysis showed that some ProRoot MTA particles, differently from Aureoseal, contain Ca, Si, Al and Fe. Oblong particles in ProRoot and Aureoseal are rich of bismuth. The strong interest in developing new Portland cement-based endodontic sealers will create materials with increased handling characteristics and physicochemical properties. A thorough investigation on two cement powders was carried out by using XRF, XRD, SEM and EDS analysis. To date there was a lack of studies on Aureoseal Plus. This cement is similar in composition to ProRoot MTA. Despite that it has distinctive elements that could improve its characteristics, resulting in a good alternative to MTA.

Comparison between different interdental stripping methods and evaluation of abrasive strips: SEM analysis.

PubMed

Grippaudo, Cristina; Cancellieri, Daniela; Grecolini, Maria E; Deli, Roberto

2010-01-01

The aim of this study was to evaluate the morphological effects and the surface irregularities produced by different methods of mechanical stripping (abrasive strips and burs) and chemical stripping (37% orthophosphoric acid) and the surface changes following the finishing procedures (polishing strips) or the subsequent application of sealants, in order to establish the right stripping method that can guarantee the smoothest surface. We have also analysed the level of wear on the different abrasive strips employed, according to their structure. 160 proximal surfaces of 80 sound molar teeth extracted for orthodontic and periodontal reasons, were divided into: 1 control group with non-treated enamel proximal surfaces and 5 different groups according to the stripping method used, were observed with scanning electron microscopy (SEM). Each one of the 5 treated groups was also divided into 3 different subgroups according to the finishing procedures or the subsequent application of sealants. The finishing stage following the manual reduction proves to be fundamental in reducing the number and depth of grooves created by the stripping. After the air rotor stripping method, the use of sealants is advised in order to obtain a smoother surface. The analysis of the combinations of mechanical and chemical stripping showed unsatisfactory results. Concerning the wear of the strips, we have highlighted a different abrasion degree for the different types of strips analysed with SEM. The enamel damages are limited only if the finishing procedure is applied, independently of the type of abrasive strip employed. It would be advisable, though clinically seldom possible, the use of sealants after the air rotor stripping technique. Copyright © 2010 Società Italiana di Ortodonzia SIDO. Published by Elsevier Srl. All rights reserved.

Seismic Wave Propagation in Fully Anisotropic Axisymmetric Media: Applications and Practical Considerations

NASA Astrophysics Data System (ADS)

van Driel, Martin; Nissen-Meyer, Tarje; Stähler, Simon; Waszek, Lauren; Hempel, Stefanie; Auer, Ludwig; Deuss, Arwen

2014-05-01

We present a numerical method to compute high-frequency 3D elastic waves in fully anisotropic axisymmetric media. The method is based on a decomposition of the wavefield into a series of uncoupled 2D equations, for which the dependence of the wavefield on the azimuth can be solved analytically. The remaining 2D problems are then solved using a spectral element method (AxiSEM). AxiSEM was recently published open-source (Nissen-Meyer et al. 2014) as a production ready code capable to compute global seismic wave propagation up to frequencies of ~2Hz. It accurately models visco-elastic dissipation and anisotropy (van Driel et al., submitted to GJI) and runs efficiently on HPC resources using up to 10K cores. At very short period, the Fresnel Zone of body waves is narrow and sensitivity is focused around the geometrical ray. In cases where the azimuthal variations of structural heterogeneity exhibit long spatial wavelengths, so called 2.5D simulations (3D wavefields in 2D models) provide a good approximation. In AxiSEM, twodimensional variations in the source-receiver plane are effectively modelled as ringlike structures extending in the out-of-plane direction. In contrast to ray-theory, which is widely used in high-frequency applications, AxiSEM provides complete waveforms, thus giving access to frequency dependency, amplitude variations, and peculiar wave effects such as diffraction and caustics. Here we focus on the practical implications of the inherent axisymmetric geometry and show how the 2.5D-features of our method method can be used to model realistic anisotropic structures, by applying it to problems such as the D" region and the inner core.

Modeling Particle Exposure in US Trucking Terminals

PubMed Central

Davis, ME; Smith, TJ; Laden, F; Hart, JE; Ryan, LM; Garshick, E

2007-01-01

Multi-tiered sampling approaches are common in environmental and occupational exposure assessment, where exposures for a given individual are often modeled based on simultaneous measurements taken at multiple indoor and outdoor sites. The monitoring data from such studies is hierarchical by design, imposing a complex covariance structure that must be accounted for in order to obtain unbiased estimates of exposure. Statistical methods such as structural equation modeling (SEM) represent a useful alternative to simple linear regression in these cases, providing simultaneous and unbiased predictions of each level of exposure based on a set of covariates specific to the exposure setting. We test the SEM approach using data from a large exposure assessment of diesel and combustion particles in the US trucking industry. The exposure assessment includes data from 36 different trucking terminals across the United States sampled between 2001 and 2005, measuring PM2.5 and its elemental carbon (EC), organic carbon (OC) components, by personal monitoring, and sampling at two indoor work locations and an outdoor “background” location. Using the SEM method, we predict: 1) personal exposures as a function of work related exposure and smoking status; 2) work related exposure as a function of terminal characteristics, indoor ventilation, job location, and background exposure conditions; and 3) background exposure conditions as a function of weather, nearby source pollution, and other regional differences across terminal sites. The primary advantage of SEMs in this setting is the ability to simultaneously predict exposures at each of the sampling locations, while accounting for the complex covariance structure among the measurements and descriptive variables. The statistically significant results and high R2 values observed from the trucking industry application supports the broader use of this approach in exposure assessment modeling. PMID:16856739

A potential utilization of end-of-life tyres as recycled carbon black in EPDM rubber.

PubMed

Sagar, M; Nibedita, K; Manohar, N; Kumar, K Raj; Suchismita, S; Pradnyesh, A; Reddy, A Babul; Sadiku, E Rotimi; Gupta, U N; Lachit, P; Jayaramudu, J

2018-04-01

End-of-life (EOL) tyres and their decomposition present severe environmental concern due to their resistance to moisture, oxygen, natural degradation, etc. Pyrolysis is considered to be the most effective and sustainable process for recycling, due to its eco-friendly process. The current work studied the effect of recycled carbon black (rCB), obtained from the pyrolysis of EOL tyres, on the properties of ethylene propylene diene rubber (EPDM). The rCB was characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and chemical methods. rCB was incorporated solely, into a conventional EPDM formulation and also in combination with N550 carbon black. The physico-mechanical properties of the EPDM vulcanizates, before and after aging, were succinctly studied by SEM, TGA, Differential Scanning Calorimetry (DSC), tensile tests and cross-link density. The average particle size of rCB was observed to be 8 µm and the ash content was observed to be higher when compared to the conventional N550 carbon black, which was evident, by the TGA and SEM-EDX analyses. The reinforcing effect and the cross-link density of the rCB-filled vulcanizates were found to be marginally inferior in comparison to the conventional carbon black (N550). The morphology of the tensile- and tear-fractured surfaces were studied by SEM and it was observed that the breaking mechanism follows the rubber chain detachment from the surface mode. Copyright © 2018 Elsevier Ltd. All rights reserved.

Intra-rater repeatability of gait parameters in healthy adults during self-paced treadmill-based virtual reality walking.

PubMed

Al-Amri, Mohammad; Al Balushi, Hilal; Mashabi, Abdulrhman

2017-12-01

Self-paced treadmill walking is becoming increasingly popular for the gait assessment and re-education, in both research and clinical settings. Its day-to-day repeatability is yet to be established. This study scrutinised the test-retest repeatability of key gait parameters, obtained from the Gait Real-time Analysis Interactive Lab (GRAIL) system. Twenty-three male able-bodied adults (age: 34.56 ± 5.12 years) completed two separate gait assessments on the GRAIL system, separated by 5 ± 3 days. Key gait kinematic, kinetic, and spatial-temporal parameters were analysed. The Intraclass-Correlation Coefficients (ICC), Standard Error Measurement (SEM), Minimum Detectable Change (MDC), and the 95% limits of agreements were calculated to evaluate the repeatability of these gait parameters. Day-to-day agreements were excellent (ICCs > 0.87) for spatial-temporal parameters with low MDC and SEM values, <0.153 and <0.055, respectively. The repeatability was higher for joint kinetic than kinematic parameters, as reflected in small values of SEM (<0.13 Nm/kg and <3.4°) and MDC (<0.335 Nm/kg and <9.44°). The obtained values of all parameters fell within the 95% limits of agreement. Our findings demonstrate the repeatability of the GRAIL system available in our laboratory. The SEM and MDC values can be used to assist researchers and clinicians to distinguish 'real' changes in gait performance over time.

Long-term changes in explosive and effusive behaviour at andesitic arc volcanoes: Chronostratigraphy of the Centre Hills Volcano, Montserrat

NASA Astrophysics Data System (ADS)

Coussens, Maya; Cassidy, Michael; Watt, Sebastian F. L.; Jutzeler, Martin; Talling, Peter J.; Barfod, Dan; Gernon, Thomas M.; Taylor, Rex; Hatter, Stuart J.; Palmer, Martin R.; Montserrat Volcano Observatory

2017-03-01

Volcanism on Montserrat (Lesser Antilles arc) has migrated southwards since the formation of the Silver Hills 2.5 Ma, and has formed three successively active volcanic centres. The Centre Hills volcano was the focus of volcanism from 1-0.4 Ma, before activity commenced at the currently active Soufrière Hills volcano. The history of activity at these two volcanoes provides an opportunity to investigate the pattern of volcano behaviour on an andesitic arc island over the lifetime of individual volcanoes. Here, we describe the pyroclastic stratigraphy of subaerial exposures around central Montserrat; identifying 11 thick (> 1 m) pumiceous units derived from sustained explosive eruptions of Centre Hills from 0.8-0.4 Ma. Over 10 other, less well- exposed pumiceous units have also been identified. The pumice-rich units are interbedded with andesite lava breccias derived from effusive, dome-forming eruptions of Centre Hills. The stratigraphy indicates that large (up to magnitude 5) explosive eruptions occurred throughout the history of Centre Hills, alongside effusive activity. This behaviour at Centre Hills contrasts with Soufrière Hills, where deposits from sustained explosive eruptions are much less common and restricted to early stages of activity at the volcano, from 175-130 ka. Subsequent eruptions at Soufriere Hills have been dominated by andesitic effusive eruptions. The bulk composition, petrography and mineral chemistry of volcanic rocks from Centre Hills and Soufrière Hills are similar throughout the history of both volcanoes, except for occasional, transient departures to different magma compositions, which mark shifts in vent location or dominant eruption style. For example, the final recorded eruption of Centre Hills, before the initiation of activity at Soufrière Hills, was more silicic than any other identified eruption on Montserrat; and the basaltic South Soufrière Hills episode marked the transition to the current stage of predominantly effusive Soufrière Hills activity. The compositional stability observed throughout the history of Centre Hills and Soufrière Hills suggests that a predominance towards effusive or explosive eruption styles is not driven by major compositional shifts of magma, but may reflect local changes in long-term magma storage conditions that characterise individual episodes (on 105 year timescales) of volcanism on Montserrat. Supplementary Table 2: Complete XRF analyses for all analysed samples Supplementary Table 3: Complete ICP-MS analyses for all analysed samples. Supplementary Table 4: Plagioclase composition and precision data from SEM analysis Supplementary Table 5: Clinopyroxene composition and precision data from SEM analysis Supplementary Table 6: Orthopyroxene composition and precision data from SEM analysis Supplementary Table 7: Amphibole composition and precision data from SEM analysis Supplementary Table 8: Glass compositions from EMP analysis Supplementary Table 9: Standard Deviation of glass compositions from EMP analysis. Supplementary Table 10: Isotopic composition of argon from plagioclase crystals from select units. Data obtained using an ARGUS V multi-collector mass spectrometer.

[Preparation of porous ceramics based on waste ceramics and its Ni2+ adsorption characteristics].

PubMed

Zhang, Yong-Li; Wang, Cheng-Zhi; Shi, Ce; Shang, Ling-Ling; Ma, Rui; Dong, Wan-Li

2013-07-01

The preparation conditions of porous ceramics were determined by SEM, XRD and FT-IR characterizations as well as the nickel removal ability of porous ceramics to be: the mass fraction w of sesbania powder doped was 4%, and the calcination temperature was 800 degrees C. SEM and pore structure characterization illustrated that calcination caused changes in the structure and morphology of waste ceramics. With the increase of calcination temperature, the specific surface area and pore volume decreased, while the aperture increased. EDS analyses showed that the main elements of both the original waste porcelain powder and the porous ceramics were Si, Al and O. The SEM, XRD and FT-IR characterization of porous ceramics illustrated that the structure of porous ceramics was stable before and after adsorption. The series of experiments of Ni2+ adsorption using these porous ceramics showed that when the dosage of porous ceramics was 10 g x L(-1), the adsorption time was 60 min, the pH value was 6.32, and the concentration of nickel-containing wastewater was below 100 mg x L(-1), the Ni2+ removal of wastewater reached 89.7%. Besides, the porous ceramics showed higher removal efficiency on nickel in the wastewater. The Ni(2+)-containing wastewater was processed by the porous ceramics prepared, and the adsorption dynamics and adsorption isotherms of Ni2+ in wastewater by porous ceramics were investigated. The research results showed that the Ni2+ adsorption process of porous ceramics was in accordance with the quasi second-order kinetic model (R2 = 0.999 9), with Q(e) of 9.09 mg x g(-1). The adsorption process can be described by the Freundlich equation and Langmuir equation, and when the temperature increased from 20 degrees C to 40 degrees C, the maximum adsorption capacity Q(m) increased from 14.49 mg x g(-1) to 15.38 mg x g(-1).

Evaluating the contribution of genetics and familial shared environment to common disease using the UK Biobank.

PubMed

Muñoz, María; Pong-Wong, Ricardo; Canela-Xandri, Oriol; Rawlik, Konrad; Haley, Chris S; Tenesa, Albert

2016-09-01

Genome-wide association studies have detected many loci underlying susceptibility to disease, but most of the genetic factors that contribute to disease susceptibility remain unknown. Here we provide evidence that part of the 'missing heritability' can be explained by an overestimation of heritability. We estimated the heritability of 12 complex human diseases using family history of disease in 1,555,906 individuals of white ancestry from the UK Biobank. Estimates using simple family-based statistical models were inflated on average by ∼47% when compared with those from structural equation modeling (SEM), which specifically accounted for shared familial environmental factors. In addition, heritabilities estimated using SNP data explained an average of 44.2% of the simple family-based estimates across diseases and an average of 57.3% of the SEM-estimated heritabilities, accounting for almost all of the SEM heritability for hypertension. Our results show that both genetics and familial environment make substantial contributions to familial clustering of disease.

Mapping temporal dynamics in social interactions with unified structural equation modeling: A description and demonstration revealing time-dependent sex differences in play behavior

PubMed Central

Beltz, Adriene M.; Beekman, Charles; Molenaar, Peter C. M.; Buss, Kristin A.

2013-01-01

Developmental science is rich with observations of social interactions, but few available methodological and statistical approaches take full advantage of the information provided by these data. The authors propose implementation of the unified structural equation model (uSEM), a network analysis technique, for observational data coded repeatedly across time; uSEM captures the temporal dynamics underlying changes in behavior at the individual level by revealing the ways in which a single person influences – concurrently and in the future – other people. To demonstrate the utility of uSEM, the authors applied it to ratings of positive affect and vigor of activity during children’s unstructured laboratory play with unfamiliar, same-sex peers. Results revealed the time-dependent nature of sex differences in play behavior. For girls more than boys, positive affect was dependent upon peers’ prior positive affect. For boys more than girls, vigor of activity was dependent upon peers’ current vigor of activity. PMID:24039386

Does Depressive Affect Mediate the Relationship between Self-Care Capacity and Nutritional Status Among Rural Older Adults? : A Structural Equation Modeling Approach.

PubMed

Jung, Seung Eun; Bishop, Alex J; Kim, Minjung; Hermann, Janice; Kim, Giyeon; Lawrence, Jeannine

2017-01-01

This study examined the relationships of self-care capacity and depressive affect on nutritional status and whether depressive affect mediated the relationship of self-care capacity on nutritional status. A convenience sample of 171 rural community-dwelling older adults, 65 years and above, participated. Structural equation modeling (SEM) was conducted to test a mediation model. The hypothesized SEM model was supported with adequate fit (χ 2 (1) = 1.87, p = 0.17; CFI = 0.94; RMSEA = 0.07; SRMR = 0.03). SEM analysis revealed a significant positive direct effect of self-care capacity on nutritional status (γ = 0.14, p = 0.042). Significant negative direct effects were observed for self-care capacity on depressive affect (γ = -0.15, p = 0.027) and for depressive affect on nutritional status (β = -0.27, p < 0.01). Depressive affect was also observed to partially mediate the relationship of self-care capacity on nutrition status (γ = 0.04, p = 0.046). Findings highlight the importance of emotional well-being on rural older adults' nutritional status, particularly those with decreased ability to engage in self-care practices.

Modeling of Individual and Organizational Factors Affecting Traumatic Occupational Injuries Based on the Structural Equation Modeling: A Case Study in Large Construction Industries

PubMed Central

Mohammadfam, Iraj; Soltanzadeh, Ahmad; Moghimbeigi, Abbas; Akbarzadeh, Mehdi

2016-01-01

Background Individual and organizational factors are the factors influencing traumatic occupational injuries. Objectives The aim of the present study was the short path analysis of the severity of occupational injuries based on individual and organizational factors. Materials and Methods The present cross-sectional analytical study was implemented on traumatic occupational injuries within a ten-year timeframe in 13 large Iranian construction industries. Modeling and data analysis were done using the structural equation modeling (SEM) approach and the IBM SPSS AMOS statistical software version 22.0, respectively. Results The mean age and working experience of the injured workers were 28.03 ± 5.33 and 4.53 ± 3.82 years, respectively. The portions of construction and installation activities of traumatic occupational injuries were 64.4% and 18.1%, respectively. The SEM findings showed that the individual, organizational and accident type factors significantly were considered as effective factors on occupational injuries’ severity (P < 0.05). Conclusions Path analysis of occupational injuries based on the SEM reveals that individual and organizational factors and their indicator variables are very influential on the severity of traumatic occupational injuries. So, these should be considered to reduce occupational accidents’ severity in large construction industries. PMID:27800465

Estimation of Bid Curves in Power Exchanges using Time-varying Simultaneous-Equations Models

NASA Astrophysics Data System (ADS)

Ofuji, Kenta; Yamaguchi, Nobuyuki

Simultaneous-equations model (SEM) is generally used in economics to estimate interdependent endogenous variables such as price and quantity in a competitive, equilibrium market. In this paper, we have attempted to apply SEM to JEPX (Japan Electric Power eXchange) spot market, a single-price auction market, using the publicly available data of selling and buying bid volumes, system price and traded quantity. The aim of this analysis is to understand the magnitude of influences to the auctioned prices and quantity from the selling and buying bids, than to forecast prices and quantity for risk management purposes. In comparison with the Ordinary Least Squares (OLS) estimation where the estimation results represent average values that are independent of time, we employ a time-varying simultaneous-equations model (TV-SEM) to capture structural changes inherent in those influences, using State Space models with Kalman filter stepwise estimation. The results showed that the buying bid volumes has that highest magnitude of influences among the factors considered, exhibiting time-dependent changes, ranging as broad as about 240% of its average. The slope of the supply curve also varies across time, implying the elastic property of the supply commodity, while the demand curve remains comparatively inelastic and stable over time.

Nanometer-scale characterization of exceptionally preserved bacterial fossils in Paleocene phosphorites from Ouled Abdoun (Morocco).

PubMed

Cosmidis, J; Benzerara, K; Gheerbrant, E; Estève, I; Bouya, B; Amaghzaz, M

2013-03-01

Micrometer-sized spherical and rod-shaped forms have been reported in many phosphorites and often interpreted as microbes fossilized by apatite, based on their morphologic resemblance with modern bacteria inferred by scanning electron microscopy (SEM) observations. This interpretation supports models involving bacteria in the formation of phosphorites. Here, we studied a phosphatic coprolite of Paleocene age originating from the Ouled Abdoun phosphate basin (Morocco) down to the nanometer-scale using focused ion beam milling, transmission electron microscopy (TEM), and scanning transmission x-ray microscopy (STXM) coupled with x-ray absorption near-edge structure spectroscopy (XANES). The coprolite, exclusively composed of francolite (a carbonate-fluroapatite), is formed by the accumulation of spherical objects, delimited by a thin envelope, and whose apparent diameters are between 0.5 and 3 μm. The envelope of the spheres is composed of a continuous crown dense to electrons, which measures 20-40 nm in thickness. It is surrounded by two thinner layers that are more porous and transparent to electrons and enriched in organic carbon. The observed spherical objects are very similar with bacteria encrusting in hydroxyapatite as observed in laboratory experiments. We suggest that they are Gram-negative bacteria fossilized by francolite, the precipitation of which started within the periplasm of the cells. We discuss the role of bacteria in the fossilization mechanism and propose that they could have played an active role in the formation of francolite. This study shows that ancient phosphorites can contain fossil biological subcellular structures as fine as a bacterial periplasm. Moreover, we demonstrate that while morphological information provided by SEM analyses is valuable, the use of additional nanoscale analyses is a powerful approach to help inferring the biogenicity of biomorphs found in phosphorites. A more systematic use of this approach could considerably improve our knowledge and understanding of the microfossils present in the geological record. © 2012 Blackwell Publishing Ltd.

Influence of a fluoridated medium with different pHs on commercially pure titanium-based implants.

PubMed

Sartori, Rafael; Correa, Cassia Bellotto; Marcantonio, Elcio; Vaz, Luis Geraldo

2009-02-01

The objective of this study was to assess the influence of a fluoride medium with different pHs on the corrosion resistance of three commercially pure titanium-based dental implant commercial brands, under scanning electron microscopy (SEM) and EDS. Forty-two dental implants, from three commercial brands, were used. Five years of regular use of mouth rinsing, with NaF 1500 ppm content and two different pHs, were simulated by immersing the specimens into that medium for 184 hours. SEM and EDS analyses demonstrated no evidence of corrosion on the specimens' surfaces after being submitted to fluoride ions or incorporation of fluoride ions to the set surface. It was possible to conclude that both the fluoride concentration and the pH of the solutions did not exert any influence upon implant corrosion resistance.

Electrical and thermal properties of Ca and Ni doped barium ferrite

NASA Astrophysics Data System (ADS)

Agrawal, Shraddha; Parveen, Azra; Azam, Ameer

2018-05-01

Ca and Ni doped M type Barium ferrite of the composition ((Ba0.9Ca0.1) (Fe0.8 Ni0.2)12O19) were prepared by the traditional sol gel auto combustion method using citric acid as a fuel. Microstructural analyses were carried out with the help of XRD and SEM. XRD analysis is the evidence of nanometer regime along with crystalline planes of hexagonal structure. It also confirms the hexagonal structure of barium ferrite even with the doping of Ca and Ni. SEM analysis is the signature of the spherical shape and surface morphology of agglomerated form of nano-powders of doped samples. The thermal properties of samples were carried out with the help of TGA. That shows the variation of weight loss of the prepared sample with the temperature.

Facile and Chemically Pure Preparation of YVO4:Eu3+ Colloid with Novel Nanostructure via Laser Ablation in Water

PubMed Central

Wang, Haohao; Odawara, Osamu; Wada, Hiroyuki

2016-01-01

A YVO4:Eu3+ colloid with an interesting nanostructure was formed by pulsed laser ablation in deionized water without any additives or surfactants. Analyses of particle morphology, composition and optical properties were accomplished by SEM, TEM, EDS PL and UV-vis. Ovoid-like particles formed by the agglomeration of numerous nanocrystals were observed by SEM and TEM, while EDS with area-mode analysis revealed that the content of dopant ion was well retained within the nanoparticles. In addition, the formation mechanism is deduced and discussed for the first time in this research. The findings of this study could provide new insights into the understanding of laser-induced oxide materials and offer an opportunity for other research groups to pursue red emitting nanophosphors with outstandingly purity. PMID:26842419

The Capabilities and Applications of FY-3A/B SEM on Monitoring Space Weather Events

NASA Astrophysics Data System (ADS)

Huang, C.; Li, J.; Yu, T.; Xue, B.; Wang, C.; Zhang, X.; Cao, G.; Liu, D.; Tang, W.

2012-12-01

The Space Environment Monitor (SEM), on board the Chinese meteorological satellites, FengYun-3A/B has the abilities to measure proton flux in 3-300 Mev energy range and electron flux in 0.15-5.7 Mev energy range. SEM can also detect the heavy ion compositions, satellite surface potential, the radiation dose in sensors, and the single events. The space environment information derived from SEM can be utilized for satellite security designs, scientific studies, development of radiation belt models, and space weather monitoring and disaster warning. In this study, the SEM's instrument characteristics are introduced and the post-launch calibration algorithm is presented. The applications in monitoring space weather events and the service for manned spaceflights are also demonstrated.; The protons with particle energy over 10 Mev are called "killer particles". These particles may damage the satellite and cause disruption of satellite's system. The protons flux of 10 M-26 Mev energy band reached 5000 in the SPE caused by a solar flare with CME during the period of 2012.01.23 to 2012.01.27 as shown in the figure. THE COMPARISONS OF HEAVY IONS (2010.11.11-2010.12.15)t;

Residential road traffic noise and general mental health in youth: The role of noise annoyance, neighborhood restorative quality, physical activity, and social cohesion as potential mediators.

PubMed

Dzhambov, Angel; Tilov, Boris; Markevych, Iana; Dimitrova, Donka

2017-12-01

Given the ubiquitous nature of both noise pollution and mental disorders, their alleged association has not escaped the spotlight of public health research. The effect of traffic noise on mental health is probably mediated by other factors, which have not been elucidated sufficiently. Herein, we aimed to disentangle the pathways linking road traffic noise to general mental health in Bulgarian youth, with a focus on several candidate mediators - noise annoyance, perceived restorative quality of the living environment, physical activity, and neighborhood social cohesion. A cross-sectional sample was collected in October - December 2016 in the city of Plovdiv, Bulgaria. It consisted of 399 students aged 15-25years, recruited from two high schools and three universities. Road traffic noise exposure (L den ) was derived from the strategic noise map of Plovdiv. Mental health was measured with the 12-item form of the General Health Questionnaire (GHQ-12). Noise annoyance, perceived restorative quality of the living environment, commuting and leisure time physical activity, and neighborhood social cohesion were assessed using validated questionnaires. Analyses were based on linear regression mediation models and a structural equation modeling (SEM) to account for the hypothesized interdependencies between candidate mediators. Results showed that higher noise exposure was associated with worse mental health only indirectly. More specifically, tests of the single and parallel mediation models indicated independent indirect paths through noise annoyance, social cohesion, and physical activity. In addition, the SEM revealed that more noise annoyance was associated with less social cohesion, and in turn with worse mental health; noise annoyance was also associated with lower neighborhood restorative quality, thereby with less social cohesion and physical activity, and in turn with worse mental health. However, causality could not be established. Further research is warranted to expand our still limited understanding of these person-environment interactions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simulation based mask defect repair verification and disposition

NASA Astrophysics Data System (ADS)

Guo, Eric; Zhao, Shirley; Zhang, Skin; Qian, Sandy; Cheng, Guojie; Vikram, Abhishek; Li, Ling; Chen, Ye; Hsiang, Chingyun; Zhang, Gary; Su, Bo

2009-10-01

As the industry moves towards sub-65nm technology nodes, the mask inspection, with increased sensitivity and shrinking critical defect size, catches more and more nuisance and false defects. Increased defect counts pose great challenges in the post inspection defect classification and disposition: which defect is real defect, and among the real defects, which defect should be repaired and how to verify the post-repair defects. In this paper, we address the challenges in mask defect verification and disposition, in particular, in post repair defect verification by an efficient methodology, using SEM mask defect images, and optical inspection mask defects images (only for verification of phase and transmission related defects). We will demonstrate the flow using programmed mask defects in sub-65nm technology node design. In total 20 types of defects were designed including defects found in typical real circuit environments with 30 different sizes designed for each type. The SEM image was taken for each programmed defect after the test mask was made. Selected defects were repaired and SEM images from the test mask were taken again. Wafers were printed with the test mask before and after repair as defect printability references. A software tool SMDD-Simulation based Mask Defect Disposition-has been used in this study. The software is used to extract edges from the mask SEM images and convert them into polygons to save in GDSII format. Then, the converted polygons from the SEM images were filled with the correct tone to form mask patterns and were merged back into the original GDSII design file. This merge is for the purpose of contour simulation-since normally the SEM images cover only small area (~1 μm) and accurate simulation requires including larger area of optical proximity effect. With lithography process model, the resist contour of area of interest (AOI-the area surrounding a mask defect) can be simulated. If such complicated model is not available, a simple optical model can be used to get simulated aerial image intensity in the AOI. With built-in contour analysis functions, the SMDD software can easily compare the contour (or intensity) differences between defect pattern and normal pattern. With user provided judging criteria, this software can be easily disposition the defect based on contour comparison. In addition, process sensitivity properties, like MEEF and NILS, can be readily obtained in the AOI with a lithography model, which will make mask defect disposition criteria more intelligent.

Semi-empirical model for retrieval of soil moisture using RISAT-1 C-Band SAR data over a sub-tropical semi-arid area of Rewari district, Haryana (India)

NASA Astrophysics Data System (ADS)

Rawat, Kishan Singh; Sehgal, Vinay Kumar; Pradhan, Sanatan; Ray, Shibendu S.

2018-03-01

We have estimated soil moisture (SM) by using circular horizontal polarization backscattering coefficient (σ o_{RH}), differences of circular vertical and horizontal σ o (σ o_{RV} {-} σ o_{RH}) from FRS-1 data of Radar Imaging Satellite (RISAT-1) and surface roughness in terms of RMS height ({RMS}_{height}). We examined the performance of FRS-1 in retrieving SM under wheat crop at tillering stage. Results revealed that it is possible to develop a good semi-empirical model (SEM) to estimate SM of the upper soil layer using RISAT-1 SAR data rather than using existing empirical model based on only single parameter, i.e., σ o. Near surface SM measurements were related to σ o_{RH}, σ o_{RV} {-} σ o_{RH} derived using 5.35 GHz (C-band) image of RISAT-1 and {RMS}_{height}. The roughness component derived in terms of {RMS}_{height} showed a good positive correlation with σ o_{RV} {-} σ o_{RH} (R2 = 0.65). By considering all the major influencing factors (σ o_{RH}, σ o_{RV} {-} σ o_{RH}, and {RMS}_{height}), an SEM was developed where SM (volumetric) predicted values depend on σ o_{RH}, σ o_{RV} {-} σ o_{RH}, and {RMS}_{height}. This SEM showed R2 of 0.87 and adjusted R2 of 0.85, multiple R=0.94 and with standard error of 0.05 at 95% confidence level. Validation of the SM derived from semi-empirical model with observed measurement ({SM}_{Observed}) showed root mean square error (RMSE) = 0.06, relative-RMSE (R-RMSE) = 0.18, mean absolute error (MAE) = 0.04, normalized RMSE (NRMSE) = 0.17, Nash-Sutcliffe efficiency (NSE) = 0.91 ({≈ } 1), index of agreement (d) = 1, coefficient of determination (R2) = 0.87, mean bias error (MBE) = 0.04, standard error of estimate (SEE) = 0.10, volume error (VE) = 0.15, variance of the distribution of differences ({S}d2) = 0.004. The developed SEM showed better performance in estimating SM than Topp empirical model which is based only on σ o. By using the developed SEM, top soil SM can be estimated with low mean absolute percent error (MAPE) = 1.39 and can be used for operational applications.

Treatment with Saccharomyces boulardii reduces the inflammation and dysfunction of the gastrointestinal tract in 5-fluorouracil-induced intestinal mucositis in mice.

PubMed

Justino, Priscilla F C; Melo, Luis F M; Nogueira, Andre F; Costa, Jose V G; Silva, Luara M N; Santos, Cecila M; Mendes, Walber O; Costa, Marina R; Franco, Alvaro X; Lima, Aldo A; Ribeiro, Ronaldo A; Souza, Marcellus H L P; Soares, Pedro M G

2014-05-01

Intestinal mucositis is an important toxic side effect of 5-fluorouracil (5-FU) treatment. Saccharomyces boulardii is known to protect from intestinal injury via an effect on the gastrointestinal microbiota. The objective of the present study was to evaluate the effect of S. boulardii on intestinal mucositis induced by 5-FU in a murine model. Mice were divided into saline, saline (control)+5-FU or 5-FU+S. boulardii (16 × 10⁹ colony-forming units/kg) treatment groups, and the jejunum and ileum were removed after killing of mice for the evaluation of histopathology, myeloperoxidase (MPO) activity, and non-protein sulfhydryl group (mainly reduced glutathione; GSH), nitrite and cytokine concentrations. To determine gastric emptying, phenol red was administered orally, mice were killed 20 min after administration, and the absorbance of samples collected from the mice was measured by spectrophotometry. Intestinal permeability was measured by the urinary excretion rate of lactulose and mannitol following oral administration. S. boulardii significantly reversed the histopathological changes in intestinal mucositis induced by 5-FU and reduced the inflammatory parameters: neutrophil infiltration (control 1·73 (SEM 0·37) ultrastructural MPO (UMPO)/mg, 5-FU 7·37 (SEM 1·77) UMPO/mg and 5-FU+S. boulardii 4·15 (SEM 0·73) UMPO/mg); nitrite concentration (control 37·00 (SEM 2·39) μm, 5-FU 59·04 (SEM 11·41) μm and 5-FU+S. boulardii 37·90 (SEM 5·78) μm); GSH concentration (control 477·60 (SEM 25·25) μg/mg, 5-FU 270·90 (SEM 38·50) μg/mg and 5-FU+S. boulardii 514·00 (SEM 38·64) μg/mg). Treatment with S. Boulardii significantly reduced the concentrations of TNF-α and IL-1β by 48·92 and 32·21 % in the jejunum and 38·92 and 61·79 % in the ileum. In addition, S. boulardii decreased the concentrations of chemokine (C-X-C motif) ligand 1 by 5-fold in the jejunum and 3-fold in the ileum. Interestingly, S. boulardii reduced the delay in gastric emptying (control 25·21 (SEM 2·55) %, 5-FU 54·91 (SEM 3·43) % and 5-FU+S. boulardii 31·38 (SEM 2·80) %) and induced the recovery of intestinal permeability (lactulose:mannitol ratio: control 0·52 (SEM 0·03), 5-FU 1·38 (SEM 0·24) and 5-FU+S. boulardii 0·62 (SEM 0·03)). In conclusion, S. boulardii reduces the inflammation and dysfunction of the gastrointestinal tract in intestinal mucositis induced by 5-FU.

The Loss Spiral of Work Pressure, Work-Home Interference and Exhaustion: Reciprocal Relations in a Three-Wave Study

ERIC Educational Resources Information Center

Demerouti, Evangelia; Bakker, Arnold B.; Bulters, Annemieke J.

2004-01-01

This study tested the "loss spiral" hypothesis of work-home interference (WHI). Accordingly, work pressure was expected to lead to WHI and exhaustion, and, vice versa, exhaustion was expected to result in more WHI and work pressure over time. Results of SEM-analyses using three waves of data obtained from 335 employees of an employment agency…

Empirical Synthesis of the Effect of Standard Error of Measurement on Decisions Made within Brief Experimental Analyses of Reading Fluency

ERIC Educational Resources Information Center

Burns, Matthew K.; Taylor, Crystal N.; Warmbold-Brann, Kristy L.; Preast, June L.; Hosp, John L.; Ford, Jeremy W.

2017-01-01

Intervention researchers often use curriculum-based measurement of reading fluency (CBM-R) with a brief experimental analysis (BEA) to identify an effective intervention for individual students. The current study synthesized data from 22 studies that used CBM-R data within a BEA by computing the standard error of measure (SEM) for the median data…

Advances in the Quantitative Characterization of the Shape of Ash-Sized Pyroclast Populations: Fractal Analyses Coupled to Micro- and Nano-Computed Tomography Techniques

NASA Astrophysics Data System (ADS)

Rausch, J.; Vonlanthen, P.; Grobety, B. H.

2014-12-01

The quantification of shape parameters in pyroclasts is fundamental to infer the dominant type of magma fragmentation (magmatic vs. phreatomagmatic), as well as the behavior of volcanic plumes and clouds in the atmosphere. In a case study aiming at reconstructing the fragmentation mechanisms triggering maar eruptions in two geologically and compositionally distinctive volcanic fields (West and East Eifel, Germany), the shapes of a large number of ash particle contours obtained from SEM images were analyzed by a dilation-based fractal method. Volcanic particle contours are pseudo-fractals showing mostly two distinct slopes in Richardson plots related to the fractal dimensions D1 (small-scale "textural" dimension) and D2 (large-scale "morphological" dimension). The validity of the data obtained from 2D sections was tested by analysing SEM micro-CT slices of one particle cut in different orientations and positions. Results for West Eifel maar particles yield large D1 values (> 1.023), resembling typical values of magmatic particles, which are characterized by a complex shape, especially at small scales. In contrast, the D1 values of ash particles from one East Eifel maar deposit are much smaller, coinciding with the fractal dimensions obtained from phreatomagmatic end-member particles. These quantitative morphological analyses suggest that the studied maar eruptions were triggered by two different fragmentation processes: phreatomagmatic in the East Eifel and magmatic in the West Eifel. The application of fractal analysis to quantitatively characterize the shape of pyroclasts and the linking of fractal dimensions to specific fragmentation processes has turned out to be a very promising tool for studying the fragmentation history of any volcanic eruption. The next step is to extend morphological analysis of volcanic particles to 3 dimensions. SEM micro-CT, already applied in this study, offers the required resolution, but is not suitable for the analysis of a large number of particles. Newly released nano CT-scanners, however, allows the simultaneous analysis of a statistically relevant number of particles (in the hundreds range). Preliminary results of a first trial will be presented.

Partial Least Squares Structural Equation Modeling with R

ERIC Educational Resources Information Center

Ravand, Hamdollah; Baghaei, Purya

2016-01-01

Structural equation modeling (SEM) has become widespread in educational and psychological research. Its flexibility in addressing complex theoretical models and the proper treatment of measurement error has made it the model of choice for many researchers in the social sciences. Nevertheless, the model imposes some daunting assumptions and…

Determinants of quality of life in patients with fibromyalgia: A structural equation modeling approach.

PubMed

Lee, Jeong-Won; Lee, Kyung-Eun; Park, Dong-Jin; Kim, Seong-Ho; Nah, Seong-Su; Lee, Ji Hyun; Kim, Seong-Kyu; Lee, Yeon-Ah; Hong, Seung-Jae; Kim, Hyun-Sook; Lee, Hye-Soon; Kim, Hyoun Ah; Joung, Chung-Il; Kim, Sang-Hyon; Lee, Shin-Seok

2017-01-01

Health-related quality of life (HRQOL) in patients with fibromyalgia (FM) is lower than in patients with other chronic diseases and the general population. Although various factors affect HRQOL, no study has examined a structural equation model of HRQOL as an outcome variable in FM patients. The present study assessed relationships among physical function, social factors, psychological factors, and HRQOL, and the effects of these variables on HRQOL in a hypothesized model using structural equation modeling (SEM). HRQOL was measured using SF-36, and the Fibromyalgia Impact Questionnaire (FIQ) was used to assess physical dysfunction. Social and psychological statuses were assessed using the Beck Depression Inventory (BDI), the State-Trait Anxiety Inventory (STAI), the Arthritis Self-Efficacy Scale (ASES), and the Social Support Scale. SEM analysis was used to test the structural relationships of the model using the AMOS software. Of the 336 patients, 301 (89.6%) were women with an average age of 47.9±10.9 years. The SEM results supported the hypothesized structural model (χ2 = 2.336, df = 3, p = 0.506). The final model showed that Physical Component Summary (PCS) was directly related to self-efficacy and inversely related to FIQ, and that Mental Component Summary (MCS) was inversely related to FIQ, BDI, and STAI. In our model of FM patients, HRQOL was affected by physical, social, and psychological variables. In these patients, higher levels of physical function and self-efficacy can improve the PCS of HRQOL, while physical function, depression, and anxiety negatively affect the MCS of HRQOL.

Determinants of quality of life in patients with fibromyalgia: A structural equation modeling approach

PubMed Central

Lee, Jeong-Won; Lee, Kyung-Eun; Park, Dong-Jin; Kim, Seong-Ho; Nah, Seong-Su; Lee, Ji Hyun; Kim, Seong-Kyu; Lee, Yeon-Ah; Hong, Seung-Jae; Kim, Hyun-Sook; Lee, Hye-Soon; Kim, Hyoun Ah; Joung, Chung-Il; Kim, Sang-Hyon

2017-01-01

Objective Health-related quality of life (HRQOL) in patients with fibromyalgia (FM) is lower than in patients with other chronic diseases and the general population. Although various factors affect HRQOL, no study has examined a structural equation model of HRQOL as an outcome variable in FM patients. The present study assessed relationships among physical function, social factors, psychological factors, and HRQOL, and the effects of these variables on HRQOL in a hypothesized model using structural equation modeling (SEM). Methods HRQOL was measured using SF-36, and the Fibromyalgia Impact Questionnaire (FIQ) was used to assess physical dysfunction. Social and psychological statuses were assessed using the Beck Depression Inventory (BDI), the State-Trait Anxiety Inventory (STAI), the Arthritis Self-Efficacy Scale (ASES), and the Social Support Scale. SEM analysis was used to test the structural relationships of the model using the AMOS software. Results Of the 336 patients, 301 (89.6%) were women with an average age of 47.9±10.9 years. The SEM results supported the hypothesized structural model (χ2 = 2.336, df = 3, p = 0.506). The final model showed that Physical Component Summary (PCS) was directly related to self-efficacy and inversely related to FIQ, and that Mental Component Summary (MCS) was inversely related to FIQ, BDI, and STAI. Conclusions In our model of FM patients, HRQOL was affected by physical, social, and psychological variables. In these patients, higher levels of physical function and self-efficacy can improve the PCS of HRQOL, while physical function, depression, and anxiety negatively affect the MCS of HRQOL. PMID:28158289

SEM-PLS Analysis of Inhibiting Factors of Cost Performance for Large Construction Projects in Malaysia: Perspective of Clients and Consultants

PubMed Central

Memon, Aftab Hameed; Rahman, Ismail Abdul

2014-01-01

This study uncovered inhibiting factors to cost performance in large construction projects of Malaysia. Questionnaire survey was conducted among clients and consultants involved in large construction projects. In the questionnaire, a total of 35 inhibiting factors grouped in 7 categories were presented to the respondents for rating significant level of each factor. A total of 300 questionnaire forms were distributed. Only 144 completed sets were received and analysed using advanced multivariate statistical software of Structural Equation Modelling (SmartPLS v2). The analysis involved three iteration processes where several of the factors were deleted in order to make the model acceptable. The result of the analysis found that R 2 value of the model is 0.422 which indicates that the developed model has a substantial impact on cost performance. Based on the final form of the model, contractor's site management category is the most prominent in exhibiting effect on cost performance of large construction projects. This finding is validated using advanced techniques of power analysis. This vigorous multivariate analysis has explicitly found the significant category which consists of several causative factors to poor cost performance in large construction projects. This will benefit all parties involved in construction projects for controlling cost overrun. PMID:24693227

SEM-PLS analysis of inhibiting factors of cost performance for large construction projects in Malaysia: perspective of clients and consultants.

PubMed

Memon, Aftab Hameed; Rahman, Ismail Abdul

2014-01-01

This study uncovered inhibiting factors to cost performance in large construction projects of Malaysia. Questionnaire survey was conducted among clients and consultants involved in large construction projects. In the questionnaire, a total of 35 inhibiting factors grouped in 7 categories were presented to the respondents for rating significant level of each factor. A total of 300 questionnaire forms were distributed. Only 144 completed sets were received and analysed using advanced multivariate statistical software of Structural Equation Modelling (SmartPLS v2). The analysis involved three iteration processes where several of the factors were deleted in order to make the model acceptable. The result of the analysis found that R(2) value of the model is 0.422 which indicates that the developed model has a substantial impact on cost performance. Based on the final form of the model, contractor's site management category is the most prominent in exhibiting effect on cost performance of large construction projects. This finding is validated using advanced techniques of power analysis. This vigorous multivariate analysis has explicitly found the significant category which consists of several causative factors to poor cost performance in large construction projects. This will benefit all parties involved in construction projects for controlling cost overrun.

Framework for SEM contour analysis

NASA Astrophysics Data System (ADS)

Schneider, L.; Farys, V.; Serret, E.; Fenouillet-Beranger, C.

2017-03-01

SEM images provide valuable information about patterning capability. Geometrical properties such as Critical Dimension (CD) can be extracted from them and are used to calibrate OPC models, thus making OPC more robust and reliable. However, there is currently a shortage of appropriate metrology tools to inspect complex two-dimensional patterns in the same way as one would work with simple one-dimensional patterns. In this article we present a full framework for the analysis of SEM images. It has been proven to be fast, reliable and robust for every type of structure, and particularly for two-dimensional structures. To achieve this result, several innovative solutions have been developed and will be presented in the following pages. Firstly, we will present a new noise filter which is used to reduce noise on SEM images, followed by an efficient topography identifier, and finally we will describe the use of a topological skeleton as a measurement tool that can extend CD measurements on all kinds of patterns.

Optimisation d'analyses de grenat almandin realisees au microscope electronique a balayage

NASA Astrophysics Data System (ADS)

Larose, Miguel

The electron microprobe (EMP) is considered as the golden standard for the collection of precise and representative chemical composition of minerals in rocks, but data of similar quality should be obtainable with a scanning electron microscope (SEM). This thesis presents an analytical protocol aimed at optimizing operational parameters of an SEM paired with an EDS Si(Li) X-ray detector (JEOL JSM-840A) for the imaging, quantitative chemical analysis and compositional X-ray maps of almandine garnet found in pelitic schists from the Canadian Cordillera. Results are then compared to those obtained for the same samples on a JEOL JXA 8900 EMP. For imaging purposes, the secondary electrons and backscattered electrons signals have been used to obtain topographic and chemical contrast of the samples, respectively. The SEM allows the acquisition of images with higher resolution than the EMP when working at high magnifications. However, for millimetric size minerals requiring very low magnifications, the EMP can usually match the imaging capabilities of an SEM. When optimizing images for both signals, the optimal operational parameters to show similar contrasts are not restricted to a unique combination of values. Optimization of operational parameters for quantitative chemical analysis resulted in analytical data with a similar precision and showing good correlation to that obtained with an EMP. Optimization of operational parameters for compositional X-ray maps aimed at maximizing the collected intensity within a pixel as well as complying with the spatial resolution criterion in order to obtain a qualitative compositional map representative of the chemical variation within the grain. Even though various corrections were needed, such as the shadow effect and the background noise removal, as well as the impossibility to meet the spatial resolution criterion because of the limited pixel density available on the SEM, the compositional X-ray maps show a good correlation with those obtained with the EMP, even for concentrations as low as 0,5%. When paired with a rigorous analytical protocol, the use of an SEM equipped with an EDS Si (Li) X-ray detector allows the collection of qualitative and quantitative results similar to those obtained with an EMP for all three of the applications considered.

Hepatic Activity and Transcription of Betaine-Homocysteine Methyltransferase, Methionine Synthase, and Cystathionine Synthase in Periparturient Dairy Cows Are Altered to Different Extents by Supply of Methionine and Choline.

PubMed

Zhou, Zheng; Garrow, Timothy A; Dong, Xianwen; Luchini, Daniel N; Loor, Juan J

2017-01-01

Compared with choline, Met enhances milk yield and feed intake, and elicits a better immuno-metabolic status in periparturient cows. It is unknown whether hepatic activity and transcription of betaine-homocysteine methyltransferase (BHMT), 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR), and cystathionine β-synthase (CBS) are responsive to Met and choline supply. This study sought to characterize hepatic BHMT, MTR, and CBS transcription and activity in response to Met and choline supplementation. Forty multiparous cows were used in a 2 × 2 factorial design from -21 d through 30 d around parturition to assess effects of dietary rumen-protected Met (0% or 0.08% dry matter basis) or rumen-protected choline (0 or 60 g · cow -1 · d -1 ). Liver tissue obtained on days -10, 7, 20, and 30 was used for analyses. Met-supplemented cows had greater methionine adenosyltransferase 1A (MAT1A) (0.38 compared with 0.27; SEM = 0.05; P = 0.02) and phosphatidylethanolamine methyltransferase (PEMT) (0.74 compared with 0.58; SEM = 0.08; P = 0.05) expression. Greater S-adenosylhomocysteine hydrolase (SAHH) (0.93 compared with 0.74; SEM = 0.05; P = 0.01) and CBS (1.16 compared with 1.02; SEM = 0.07; P = 0.04), as well as lower MTR activity (23.4 compared with 29.7 nmol product · h -1 · mg protein -1 ; SEM = 2.9; P = 0.04), also were detected in Met- but not choline-supplemented cows. Although BHMT and MTR expression and BHMT enzyme activity did not change (P > 0.05), MTR enzyme activity was lower in choline-supplemented cows (23.5 compared with 29.6 nmol product · h -1 · mg protein -1 ; SEM = 2.9; P = 0.05). These findings indicate that greater synthesis of phosphatidylcholine and antioxidants contribute to the better performance and immuno-metabolic status in Met-supplemented cows. Failure to generate a comparable amount of endogenous Met from choline could be one reason that choline-fed cows fail to achieve comparable performance and health benefits during the periparturient period. © 2017 American Society for Nutrition.

Quantitative Determination of Noa (Naturally Occurring Asbestos) in Rocks : Comparison Between Pcom and SEM Analysis

NASA Astrophysics Data System (ADS)

Baietto, Oliviero; Amodeo, Francesco; Giorgis, Ilaria; Vitaliti, Martina

2017-04-01

The quantification of NOA (Naturally Occurring Asbestos) in a rock or soil matrix is complex and subject to numerous errors. The purpose of this study is to compare two fundamental methodologies used for the analysis: the first one uses Phase Contrast Optical Microscope (PCOM) while the second one uses Scanning Electron Microscope (SEM). The two methods, although they provide the same result, which is the asbestos mass to total mass ratio, have completely different characteristics and both present pros and cons. The current legislation in Italy involves the use of SEM, DRX, FTIR, PCOM (DM 6/9/94) for the quantification of asbestos in bulk materials and soils and the threshold beyond which the material is considered as hazardous waste is a concentration of asbestos fiber of 1000 mg/kg.(DM 161/2012). The most used technology is the SEM which is the one among these with the better analytical sensitivity.(120mg/Kg DM 6 /9/94) The fundamental differences among the analyses are mainly: - Amount of analyzed sample portion - Representativeness of the sample - Resolution - Analytical precision - Uncertainty of the methodology - Operator errors Due to the problem of quantification of DRX and FTIR (1% DM 6/9/94) our Asbestos Laboratory (DIATI POLITO) since more than twenty years apply the PCOM methodology and in the last years the SEM methodology for quantification of asbestos content. The aim of our research is to compare the results obtained from a PCOM analysis with the results provided by SEM analysis on the base of more than 100 natural samples both from cores (tunnel-boring or explorative-drilling) and from tunnelling excavation . The results obtained show, in most cases, a good correlation between the two techniques. Of particular relevance is the fact that both techniques are reliable for very low quantities of asbestos, even lower than the analytical sensitivity. This work highlights the comparison between the two techniques emphasizing strengths and weaknesses of the two procedures and suggests how an integrated approach, together with the skills and experience of the operator may be the best way forward in order to obtain a constructive improvement of analysis techniques.

It could have been me: vicarious victims and disaster-focused distress.

PubMed

Wayment, Heidi A

2004-04-01

College students who had experienced no personal bereavement in the September 11 terrorist attacks completed questionnaires between 3 and 5 weeks after the attacks and 5 months later. Cross-sectional and longitudinal structural equation model (SEM) analyses revealed that general distress and disaster-focused distress are discernable reactions following a collective loss. Both types of distress were higher among women and by those reporting social strain. General distress was associated with previous stressful events and mental health issues. Perceived similarity to the victims predicted disaster-focused distress and mediated the relationship between attending to media accounts of victims and disaster-focused distress. Only the disaster-focused distress reactions of survivor guilt and grief were associated with collective helping behaviors after the attacks and, for women, these behaviors were associated with greater reductions in these distress reactions over time. Discussion focuses on the importance of examining disaster-focused distress reactions following collective loss.

The catechol-O-methyltransferase gene (COMT) and cognitive function from childhood through adolescence

PubMed Central

Gaysina, Darya; Xu, Man K.; Barnett, Jennifer H.; Croudace, Tim J.; Wong, Andrew; Richards, Marcus; Jones, Peter B.

2013-01-01

Genetic variation in the catechol-O-methyltransferase gene (COMT) can influence cognitive function, and this effect may depend on developmental stage. Using a large representative British birth cohort, we investigated the effect of COMT on cognitive function (verbal and non-verbal) at ages 8 and 15 years taking into account the possible modifying effect of pubertal stage. Five functional COMT polymorphisms, rs6269, rs4818, rs4680, rs737865 and rs165599 were analysed. Associations between COMT polymorphisms and cognition were tested using regression and latent variable structural equation modelling (SEM). Before correction for multiple testing, COMT rs737865 showed association with reading comprehension, verbal ability and global cognition at age 15 years in pubescent boys only. Although there was some evidence for age- and sex-specific effects of the COMT rs737865 none remained significant after correction for multiple testing. Further studies are necessary in order to make firmer conclusions. PMID:23178897

The effects of physically active leisure on stress-health relationships.

PubMed

Iwasaki, Y; Zuzanek, J; Mannell, R C

2001-01-01

In this article, the effects of physically active leisure on the relationships between stress and health are examined using structural equation modeling (SEM). The analyses are based on data from Canada's 1994 National Population Health Survey (n = 17,626). Overall, physically active leisure was found to directly contribute to higher levels of physical health and wellbeing, and lower levels of mental ill-health among Canadians. When the respondents experienced higher levels of chronic stress, life event stress, and/or work stress, involvement in physically active leisure appeared to help them maintain good health and wellbeing. Also, higher levels of participation in physically active leisure helped paid workers suppress levels of work stress. Agencies involved in health promotion and lifestyle intervention should give greater consideration to physically active leisure. As a significant component of an active lifestyle, physically active leisure can contribute to better health, and provide a valuable resource for coping with stress.

Consumer purchase intention towards environmentally friendly vehicles: an empirical investigation in Kuala Lumpur, Malaysia.

PubMed

Afroz, Rafia; Masud, Muhammad Mehedi; Akhtar, Rulia; Islam, Md Ashraful; Duasa, Jarita Bt

2015-10-01

This paper examines whether attitudes towards electric vehicles (ATEVs), subjective norms (SNs) and perceived behavioural control (PBC) have significant associations with consumer purchase intention (PI) and the purchase behaviour of environmentally friendly vehicles (EFVs). The results from the survey questionnaires are analysed using confirmatory factor analysis (CFA) and structural equation modelling (SEM). The findings of this paper indicate that ATEV, SN and PBC significantly influence PI. This finding also indicates that environmental consequence and individual preferences do not influence the PI of the respondents. We found that Malaysian car owners are largely unaware of the greenhouse effects on the environment or attach to it little importance, which is reflected in their PI towards EFVs. The outcomes of this study could help policymakers design programmes to influence attitudes, subjective norms, perceived behavioural control and purchase behaviour to prevent further air pollution and reduce CO2 emissions from the transportation sector.

Boehmite-An Efficient and Recyclable Acid-Base Bifunctional Catalyst for Aldol Condensation Reaction.

PubMed

Reshma, P C Rajan; Vikneshvaran, Sekar; Velmathi, Sivan

2018-06-01

In this work boehmite was used as an acid-base bifunctional catalyst for aldol condensation reactions of aromatic aldehydes and ketones. The catalyst was prepared by simple sol-gel method using Al(NO3)3·9H2O and NH4OH as precursors. The catalyst has been characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), UV-visible spectroscopy (DRS), BET surface area analyses. Boehmite is successfully applied as catalyst for the condensation reaction between 4-nitrobenzaldehyde and acetone as a model substrate giving α, β-unsaturated ketones without any side product. The scope of the reaction is extended for various substituted aldehydes. A probable mechanism has been suggested to explain the cooperative behavior of the acidic and basic sites. The catalyst is environmentally friendly and easily recovered from the reaction mixture. Also the catalyst is reusable up to 3 catalytic cycles.

The Effect of Microstructure On Transport Properties of Porous Electrodes

NASA Astrophysics Data System (ADS)

Peterson, Serena W.

The goal of this work is to further understand the relationships between porous electrode microstructure and mass transport properties. This understanding allows us to predict and improve cell performance from fundamental principles. The investigated battery systems are the widely used rechargeable Li-ion battery and the non-rechargeable alkaline battery. This work includes three main contributions in the battery field listed below. Direct Measurement of Effective Electronic Transport in Porous Li-ion Electrodes. An accurate assessment of the electronic conductivity of electrodes is necessary for understanding and optimizing battery performance. The bulk electronic conductivity of porous LiCoO2-based cathodes was measured as a function of porosity, pressure, carbon fraction, and the presence of an electrolyte. The measurements were performed by delamination of thin-film electrodes from their aluminum current collectors and by use of a four-line probe. Imaging and Correlating Microstructure To Conductivity. Transport properties of porous electrodes are strongly related to microstructure. An experimental 3D microstructure is needed not only for computation of direct transport properties, but also for a detailed electrode microstructure characterization. This work utilized X-ray tomography and focused ion beam (FIB)/scanning electron microscopy (SEM) to obtain the 3D structures of alkaline battery cathodes. FIB/SEM has the advantage of detecting carbon additives; thus, it was the main tomography tool employed. Additionally, protocols and techniques for acquiring, processing and segmenting series of FIB/SEM images were developed as part of this work. FIB/SEM images were also used to correlate electrodes' microstructure to their respective conductivities for both Li-ion and alkaline batteries. Electrode Microstructure Metrics and the 3D Stochastic Grid Model. A detailed characterization of microstructure was conducted in this work, including characterization of the volume fraction, nearest neighbor probability, domain size distribution, shape factor, and Fourier transform coefficient. These metrics are compared between 2D FIB/SEM, 3D FIB/SEM and X-ray structures. Among those metrics, the first three metrics are used as a basis for SG model parameterization. The 3D stochastic grid (SG) model is based on Monte Carlo techniques, in which a small set of fundamental inter-domain parameters are used to generate structures. This allows us to predict electrode microstructure and its effects on both electronic and ionic properties.

1998 Technology Showcase. JOAP International Condition Monitoring Conference.

DTIC Science & Technology

1998-04-01

Systems using Automated SEM/ EDX and New Diagnostic Routines 276 N. W Farrant & T. Luckhurst ADVANCED DIAGNOSTIC SYSTEMS Model-Based Diagnostics of Gas...Microscopy with Energy Dispersive X-Ray (SEM/ EDX ) micro analysis packages and Energy Dispersive X-Ray Fluorescence (EDXRF) analytical equipment. Therqfore...wear particles separated by ferrogram method. a- I WEAR PARTICLE A SLAS 97 (HOME PAGE) Fig I Home Page NONFE;RROUS MATERIAL A wW~ a48 -1, rV fr , ý b

Construyendo un Puente entre la Educacion del Dotado y el Mejoramiento Escolar Integral. Resumen. La Serie de Decision Basada en la Investigacion (Building a Bridge between Gifted Education and Total School Improvement. Summary. Talent Development Research-Based Decision Making Series).

ERIC Educational Resources Information Center

Renzulli, Joseph S.

This monograph addresses the role of gifted education in total school improvement by describing three service delivery components (the Total Talent Portfolio, Curriculum Modification Techniques, and Enrichment Learning and Teaching) and several organizational components of the Schoolwide Enrichment Model (SEM). The report describes how the SEM can…

Underground Habitats in the Río Tinto Basin: A Model for Subsurface Life Habitats on Mars

NASA Astrophysics Data System (ADS)

Fernández-Remolar, David C.; Prieto-Ballesteros, Olga; Rodríguez, Nuria; Gómez, Felipe; Amils, Ricardo; Gómez-Elvira, Javier; Stoker, Carol R.

2008-10-01

A search for evidence of cryptic life in the subsurface region of a fractured Paleozoic volcanosedimentary deposit near the source waters of the Río Tinto River (Iberian pyrite belt, southwest Spain) was carried out by Mars Astrobiology Research and Technology Experiment (MARTE) project investigators in 2003 and 2004. This conventional deep-drilling experiment is referred to as the MARTE ground truth drilling project. Boreholes were drilled at three sites, and samples from extracted cores were analyzed with light microscopy, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy. Core leachates were analyzed with ion chromatography, and borehole fluids were analyzed with ion and gas chromatography. Key variables of the groundwater system (e.g. , pO2, pH, and salinity) exhibit huge ranges probably due to surficial oxygenation of overall reducing waters, physical mixing of waters, and biologically mediated water-rock interactions. Mineral distribution is mainly driven by the pH of subsurface solutions, which range from highly acidic to neutral. Borehole fluids contain dissolved gases such as CO2, CH4, and H2. SEM-EDS analyses of core samples revealed evidence of microbes attacking pyrite. The Río Tinto alteration mechanisms may be similar to subsurface weathering of the martian crust and provide insights into the possible (bio)geochemical cycles that may have accompanied underground habitats in extensive early Mars volcanic regions and associated sulfide ores.

Underground habitats in the Río Tinto basin: a model for subsurface life habitats on Mars.

PubMed

Fernández-Remolar, David C; Prieto-Ballesteros, Olga; Rodríguez, Nuria; Gómez, Felipe; Amils, Ricardo; Gómez-Elvira, Javier; Stoker, Carol R

2008-10-01

A search for evidence of cryptic life in the subsurface region of a fractured Paleozoic volcanosedimentary deposit near the source waters of the Río Tinto River (Iberian pyrite belt, southwest Spain) was carried out by Mars Astrobiology Research and Technology Experiment (MARTE) project investigators in 2003 and 2004. This conventional deep-drilling experiment is referred to as the MARTE ground truth drilling project. Boreholes were drilled at three sites, and samples from extracted cores were analyzed with light microscopy, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy. Core leachates were analyzed with ion chromatography, and borehole fluids were analyzed with ion and gas chromatography. Key variables of the groundwater system (e.g., pO(2), pH, and salinity) exhibit huge ranges probably due to surficial oxygenation of overall reducing waters, physical mixing of waters, and biologically mediated water-rock interactions. Mineral distribution is mainly driven by the pH of subsurface solutions, which range from highly acidic to neutral. Borehole fluids contain dissolved gases such as CO(2), CH(4), and H(2). SEM-EDS analyses of core samples revealed evidence of microbes attacking pyrite. The Río Tinto alteration mechanisms may be similar to subsurface weathering of the martian crust and provide insights into the possible (bio)geochemical cycles that may have accompanied underground habitats in extensive early Mars volcanic regions and associated sulfide ores.

Does natural variation in diversity affect biotic resistance?

USGS Publications Warehouse

Harrison, Susan; Cornell, Howard; Grace, James B.

2015-01-01

Theories linking diversity to ecosystem function have been challenged by the widespread observation of more exotic species in more diverse native communities. Few studies have addressed the key underlying process by dissecting how community diversity is shaped by the same environmental gradients that determine biotic and abiotic resistance to new invaders. In grasslands on highly heterogeneous soils, we used addition of a recent invader, competitor removal and structural equation modelling (SEM) to analyse soil influences on community diversity, biotic and abiotic resistance and invader success. Biotic resistance, measured by reduction in invader success in the presence of the resident community, was negatively correlated with species richness and functional diversity. However, in the multivariate SEM framework, biotic resistance was independent of all forms of diversity and was positively affected by soil fertility via community biomass. Abiotic resistance, measured by invader success in the absence of the resident community, peaked on infertile soils with low biomass and high community diversity. Net invader success was determined by biotic resistance, consistent with this invader's better performance on infertile soils in unmanipulated conditions. Seed predation added slightly to biotic resistance without qualitatively changing the results. Soil-related genotypic variation in the invader also did not affect the results. Synthesis. In natural systems, diversity may be correlated with invasibility and yet have no effect on either biotic or abiotic resistance to invasion. More generally, the environmental causes of variation in diversity should not be overlooked when considering the potential functional consequences of diversity.

Does case-mix based reimbursement stimulate the development of process-oriented care delivery?

PubMed

Vos, Leti; Dückers, Michel L A; Wagner, Cordula; van Merode, Godefridus G

2010-11-01

Reimbursement based on the total care of a patient during an acute episode of illness is believed to stimulate management and clinicians to reduce quality problems like waiting times and poor coordination of care delivery. Although many studies already show that this kind of case-mix based reimbursement leads to more efficiency, it remains unclear whether care coordination improved as well. This study aims to explore whether case-mix based reimbursement stimulates development of care coordination by the use of care programmes, and a process-oriented way of working. Data for this study were gathered during the winter of 2007/2008 in a survey involving all Dutch hospitals. Descriptive and structural equation modelling (SEM) analyses were conducted. SEM reveals that adoption of the case-mix reimbursement within hospitals' budgeting processes stimulates hospitals to establish care programmes by the use of process-oriented performance measures. However, the implementation of care programmes is not (yet) accompanied by a change in focus from function (the delivery of independent care activities) to process (the delivery of care activities as being connected to a chain of interdependent care activities). This study demonstrates that hospital management can stimulate the development of care programmes by the adoption of case-mix reimbursement within hospitals' budgeting processes. Future research is recommended to confirm this finding and to determine whether the establishment of care programmes will in time indeed lead to a more process-oriented view of professionals. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Investigation of physical and mechanical properties of (BaSnO3)x(Bi,Pb)-2223 composite

NASA Astrophysics Data System (ADS)

Habanjar, K.; Barakat, M. M. E.; Awad, R.

2017-07-01

The effect of BaSnO3 nanoparticles addition on the structural and mechanical properties of (Bi,Pb)-2223 superconducting phase by means of X-rays diffraction analysis (XRD), scanning electron microscope (SEM), electrical resistance and Vickers microhardness measurement was studied. BaSnO3 nanomaterial and (BaSnO3)x(Bi,Pb)-2223 superconducting samples were prepared using co-precipitation method and standard solid-state reaction techniques, respectively. From XRD data, the addition of BaSnO3 into (Bi,Pb)-2223 phase does not affect the tetragonal structure and the lattice parameters. SEM images indicate that the microstructure of (Bi,Pb)-2223 was enhanced by adding BaSnO3 nanoparticles by filling its pores and voids. The superconducting transition temperature Tc as well as the critical transport current density Jc, estimated from electrical resistivity measurements, are increased up to x = 0.5 wt%, then decreased with further increase in x. Vickers microhardness measurements Hv were carried out at room temperature as a function of applied. The experimental Hv results were analysed in view of Meyer’s law, Hays and Kendall (HK) approach, elastic/plastic deformation (EPD) and proportional specimen resistance (PSR). All samples exhibit normal indentation size effect (ISE), in addition to that, the analysis shows that the Hays and Kendall model is the most suitable one to describe the load independent microhardness for (BaSnO3)x(Bi,Pb)-2223 superconducting samples.

Biosorption of Microelements by Spirulina: Towards Technology of Mineral Feed Supplements

PubMed Central

Chojnacka, Katarzyna

2014-01-01

Surface characterization and metal ion adsorption properties of Spirulina sp. and Spirulina maxima were verified by various instrumental techniques. FTIR spectroscopy and potentiometric titration were used for qualitative and quantitative determination of metal ion-binding groups. Comparative FTIR spectra of natural and Cu(II)-treated biomass proved involvement of both phosphoryl and sulfone groups in metal ions sorption. The potentiometric titration data analysis provided the best fit with the model assuming the presence of three types of surface functional groups and the carboxyl group as the major binding site. The mechanism of metal ions biosorption was investigated by comparing the results from multielemental analyses by ICP-OES and SEM-EDX. Biosorption of Cu(II), Mn(II), Zn(II), and Co(II) ions by lyophilized Spirulina sp. was performed to determine the metal affinity relationships for single- and multicomponent systems. Obtained results showed the replacement of naturally bound ions: Na(I), K(I), or Ca(II) with sorbed metal ions in a descending order of Mn(II) > Cu(II) > Zn(II) > Co(II) for single- and Cu(II) > Mn(II) > Co(II) > Zn(II) for multicomponent systems, respectively. Surface elemental composition of natural and metal-loaded material was determined both by ICP-OES and SEM-EDX analysis, showing relatively high value of correlation coefficient between the concentration of Na(I) ions in algal biomass. PMID:25386594

Efficacy of calcium oxide and calcium hydroxide nanoparticles on the elimination of Enterococcus faecalis in human root dentin.

PubMed

Louwakul, Phumisak; Saelo, Attapon; Khemaleelakul, Saengusa

2017-04-01

The objective of this study was to compare the antibacterial effect of calcium oxide nanoparticles (CONPs) and calcium hydroxide nanoparticles (CHNPs) against Enterococcus faecalis in a dentinal block model. E. faecalis strain JCM 7783 was introduced into dentinal tubules of semicylindrical dentin specimens by centrifugation and incubated for 1 week. Fifty microliters of CONPs or CHNPs was placed on the root canal side of the infected dentin specimens. The specimens were then incubated in aerobic condition at 37 °C and 100 % relative humidity for 1 week. The treated dentin specimens were subjected to fluorescent staining and confocal laser scanning microscopy (CLSM) to analyze the proportions of non-vital and vital bacterial cells inside the dentinal tubules. Scanning electron microscopy (SEM) was used to confirm the effect of the medicaments on the bacteria in the dentinal tubules. Calcium oxide (CO) and calcium hydroxide (CH) were used as controls. Based on the CLSM and SEM analyses, CHNPs were more efficient than CONPs in the elimination of the bacteria in the dentinal tubules. CONPs significantly killed more E. faecalis than CO and CH (P < .05). Neither CO nor CH was able to kill the bacteria. CHNPs were more effective than CONPs in the elimination of E. faecalis in dentinal tubules. CHNPs are effective nanoparticles in killing endodontic bacteria present in dentinal tubules. They have potential as an intracanal medicament, which may be beneficial in root canal therapy.

Synthesis, characterization, thermal and antimicrobial studies of diabetic drug models: Complexes of vanadyl(II) sulfate with ascorbic acid (vitamin C), riboflavin (vitamin B2) and nicotinamide (vitamin B3)

NASA Astrophysics Data System (ADS)

Refat, Moamen S.

2010-04-01

The oxovanadium(II) complexes of the different vitamins like ascorbic acid (vitamin C; Vit. C), riboflavin (vitamin B2; Vit. B2) and nicotinamide (vitamin B3; Vit. B3) were synthesized and characterized by elemental analysis, molar conductance, IR, electronic, magnetic measurements, thermal studies, XRD and SEM. Conductance measurements indicated that the vanadyl(II) complexes of Vit. B2 and Vit. B3 are 1:2 electrolytes except for [VO(Vit. C) 2(H 2O) 2] complex is non-electrolyte. IR data show that Vit. B2 is bidentate ligand against azomethine nitrogen of pyrazine ring and C dbnd O of pyrimidine-2,4-dione but Vit. B3 and Vit. C acts as a monodentate ligand through pyridine nitrogen and hydroxo oxygen of furan ring, respectively. Electronic spectral measurements indicated that all VO(II) complexes have a square-pyramidal geometry. Magnetic measurements for the new vanadyl(II) complexes are in a good agreement with the proposed formula. Thermal analyses (TG/DSC) of the studied complexes show that the decomposition process takes place in more than two steps. XRD refer that VO(II) complexes have an amorphous behavior. The surface morphology of the complexes was studied by SEM. The antimicrobial activities of the ligands and its complexes indicate that the vanadyl(II) complexes possess high antibacterial and antifungal activities towards the bacterial species and the fungal species than start ligands.

Assessing overall patient satisfaction in inflammatory bowel disease using structural equation modeling.

PubMed

Soares, João-Bruno; Marinho, Ana S; Fernandes, Dália; Moreira Gonçalves, Bruno; Camila-Dias, Cláudia; Gonçalves, Raquel; Magro, Fernando

2015-08-01

Structural equation modeling (SEM) is a very popular data-analytic technique for the evaluation of customer satisfaction. We aimed to measure the overall satisfaction of inflammatory bowel disease (IBD) patients with healthcare in Portugal and to define its main determinants using SEM. The study included three steps: (i) specification of a patient satisfaction model that included the following dimensions: Image, Expectations, Facilities, Admission process, Assistant staff, Nursing staff, Medical staff, Treatment, Inpatient care, Outpatient care, Overall quality, Overall satisfaction, and Loyalty; (ii) sample survey from 2000 patients, members of the Portuguese Association of the IBD; and (iii) estimation of the satisfaction model using partial least squares (XLSTAT-PLSPM). We received 498 (25%) valid questionnaires from 324 (66%) patients with Crohn's disease and 162 (33%) patients with ulcerative colitis. Our model provided a substantial explanation for Overall satisfaction (R=0.82). The mean index of overall satisfaction was 74.4 (0-100 scale). The main determinants of Overall satisfaction were the Image (β=0.26), Outpatient care (β=0.23), and Overall quality (β=0.21), whose mean indices were 83, 75, and 81, respectively. Facilities and Inpatient care were the variables with a significant impact on Overall satisfaction and the worst mean indices. SEM is useful for the evaluation of IBD patient satisfaction. The Overall satisfaction of IBD patients with healthcare in Portugal is good, but to increase it, IBD services need to focus on the improvement of Outpatient care, Facilities, and Inpatient care. Our model could be a matrix for a global model of IBD patient satisfaction.

Psychological models for development of motorcycle helmet use among students in Vietnam

NASA Astrophysics Data System (ADS)

Kumphong, J.; Satiennam, T.; Satiennam, W.; Trinh, Tu Anh

2018-04-01

A helmet can reduce head accident severity. The aim of this research study was to study the intention for helmet use of students who ride motorcycles in Vietnam, by Structural Equation Modeling (SEM). Questionnaires developed by several traffic psychology modules, including the Theory of Planned Behaviour (TPB), Traffic Locus of Control (T-LOC), and Health Belief Model (HBM), were distributed to students at Ton Thang University and University of Architecture, Ho Chi Minh City. SEM was used to explain helmet use behaviour. The results indicate that TPB, T-LOC and HBM could explain the variance in helmet use behaviour. However, TPB can explain behaviour (helmet use intention) better than T-LOC and HBM. The outcome of this study is useful for the agencies responsible to improve motorcycle safety.

A structural Model of Self-efficacy in Handball Referees

PubMed Central

Diotaiuti, Pierluigi; Falese, Lavinia; Mancone, Stefania; Purromuto, Francesco

2017-01-01

The study aimed to identify factors predicting self-efficacy in a sample of 248 Italian handball referees. The main hypothesis was that perception of teamwork efficacy would be a significant predictor of self-efficacy in handball referees. Participants completed an online questionnaire including Referee Self-Efficacy Scale (α = 0.85), Self-Determination Scale (α = 0.78), and an adaptation for Referees of the Sport Commitment Model (α = 0.80). Two hierarchical regression analyses have identified: (1) Enjoyment (β = 0.226), Couple Efficacy (β = 0.233), and Personal Awareness (β = 0.243), as predictors of Self-Efficacy; (2) Span of Co-Refereeing (β = 0.253), Perceived Quality of the Relationship (β = 0.239), and Mutual Agreement (β = 0.274), as predictors of Couple Self-Efficacy. A further SEM analysis confirmed the fit of a structural model of Self-efficacy considering the reciprocal influence of Couple Efficacy, Enjoyment and Awareness (χ2: 5.67; RMSEA: 0.000; SRMR: 0.019). The study underlines the importance of teamwork (or co-refereeing) as it relates to enjoyment and awareness in officiating and how it enhances the psychological well-being of handball referees. Future studies should investigate the relationship between factors influencing perceived teamwork efficacy and officiating performance outcome. PMID:28572783

Predicting adolescents' disclosure of personal information in exchange for commercial incentives: an application of an extended theory of planned behavior.

PubMed

Heirman, Wannes; Walrave, Michel; Ponnet, Koen

2013-02-01

This study adopts a global theoretical framework to predict adolescents' disclosure of personal information in exchange for incentives offered by commercial Websites. The study postulates and tests the validity of a model based on the theory of planned behavior (TPB), including antecedent factors of attitude and perceived behavioral control (PBC). A survey was conducted among 1,042 respondents. Results from SEM analyses show that the hypothesized model fits the empirical data well. The model accounts for 61.9 percent of the variance in adolescents' intention to disclose and 43.7 percent of the variance in self-reported disclosure. Perceived social pressure exerted by significant others (subjective norm) is the most important TPB factor in predicting intention to disclose personal information in exchange for incentives. This finding suggests that in discussions of adolescents' information privacy, the importance of social factors outweighs the individually oriented TPB factors of attitude and PBC. Moreover, privacy concern and trust propensity are significant predictors of respondents' attitudes toward online disclosure in exchange for commercial incentives, whereas the frequency of Internet use significantly affects their level of PBC.

FIB-SEM tomography in biology.

PubMed

Kizilyaprak, Caroline; Bittermann, Anne Greet; Daraspe, Jean; Humbel, Bruno M

2014-01-01

Three-dimensional information is much easier to understand than a set of two-dimensional images. Therefore a layman is thrilled by the pseudo-3D image taken in a scanning electron microscope (SEM) while, when seeing a transmission electron micrograph, his imagination is challenged. First approaches to gain insight in the third dimension were to make serial microtome sections of a region of interest (ROI) and then building a model of the object. Serial microtome sectioning is a tedious and skill-demanding work and therefore seldom done. In the last two decades with the increase of computer power, sophisticated display options, and the development of new instruments, an SEM with a built-in microtome as well as a focused ion beam scanning electron microscope (FIB-SEM), serial sectioning, and 3D analysis has become far easier and faster.Due to the relief like topology of the microtome trimmed block face of resin-embedded tissue, the ROI can be searched in the secondary electron mode, and at the selected spot, the ROI is prepared with the ion beam for 3D analysis. For FIB-SEM tomography, a thin slice is removed with the ion beam and the newly exposed face is imaged with the electron beam, usually by recording the backscattered electrons. The process, also called "slice and view," is repeated until the desired volume is imaged.As FIB-SEM allows 3D imaging of biological fine structure at high resolution of only small volumes, it is crucial to perform slice and view at carefully selected spots. Finding the region of interest is therefore a prerequisite for meaningful imaging. Thin layer plastification of biofilms offers direct access to the original sample surface and allows the selection of an ROI for site-specific FIB-SEM tomography just by its pronounced topographic features.

Fall Detection in Individuals With Lower Limb Amputations Using Mobile Phones: Machine Learning Enhances Robustness for Real-World Applications.

PubMed

Shawen, Nicholas; Lonini, Luca; Mummidisetty, Chaithanya Krishna; Shparii, Ilona; Albert, Mark V; Kording, Konrad; Jayaraman, Arun

2017-10-11

Automatically detecting falls with mobile phones provides an opportunity for rapid response to injuries and better knowledge of what precipitated the fall and its consequences. This is beneficial for populations that are prone to falling, such as people with lower limb amputations. Prior studies have focused on fall detection in able-bodied individuals using data from a laboratory setting. Such approaches may provide a limited ability to detect falls in amputees and in real-world scenarios. The aim was to develop a classifier that uses data from able-bodied individuals to detect falls in individuals with a lower limb amputation, while they freely carry the mobile phone in different locations and during free-living. We obtained 861 simulated indoor and outdoor falls from 10 young control (non-amputee) individuals and 6 individuals with a lower limb amputation. In addition, we recorded a broad database of activities of daily living, including data from three participants' free-living routines. Sensor readings (accelerometer and gyroscope) from a mobile phone were recorded as participants freely carried it in three common locations-on the waist, in a pocket, and in the hand. A set of 40 features were computed from the sensors data and four classifiers were trained and combined through stacking to detect falls. We compared the performance of two population-specific models, trained and tested on either able-bodied or amputee participants, with that of a model trained on able-bodied participants and tested on amputees. A simple threshold-based classifier was used to benchmark our machine-learning classifier. The accuracy of fall detection in amputees for a model trained on control individuals (sensitivity: mean 0.989, 1.96*standard error of the mean [SEM] 0.017; specificity: mean 0.968, SEM 0.025) was not statistically different (P=.69) from that of a model trained on the amputee population (sensitivity: mean 0.984, SEM 0.016; specificity: mean 0.965, SEM 0.022). Detection of falls in control individuals yielded similar results (sensitivity: mean 0.979, SEM 0.022; specificity: mean 0.991, SEM 0.012). A mean 2.2 (SD 1.7) false alarms per day were obtained when evaluating the model (vs mean 122.1, SD 166.1 based on thresholds) on data recorded as participants carried the phone during their daily routine for two or more days. Machine-learning classifiers outperformed the threshold-based one (P<.001). A mobile phone-based fall detection model can use data from non-amputee individuals to detect falls in individuals walking with a prosthesis. We successfully detected falls when the mobile phone was carried across multiple locations and without a predetermined orientation. Furthermore, the number of false alarms yielded by the model over a longer period of time was reasonably low. This moves the application of mobile phone-based fall detection systems closer to a real-world use case scenario. ©Nicholas Shawen, Luca Lonini, Chaithanya Krishna Mummidisetty, Ilona Shparii, Mark V Albert, Konrad Kording, Arun Jayaraman. Originally published in JMIR Mhealth and Uhealth (http://mhealth.jmir.org), 11.10.2017.

Synthesis of zeolite/nickel ferrite/sodium alginate bionanocomposite via a co-precipitation technique for efficient removal of water-soluble methylene blue dye.

PubMed

Bayat, Mahsa; Javanbakht, Vahid; Esmaili, Javad

2018-05-05

In this study, we sought to synthesize magnetic nanocomposite of zeolite/nickel ferrite through co-precipitation method and modify its surface by sodium alginate to enhance its methylene blue adsorption capacity and to prevent its oxidation. Nanocomposite characteristics were investigated by SEM, VSM, XRD and FTIR analyses. The results indicate that nanocomposite synthesis and modification has been completely successful. Adsorption thermodynamics, kinetics, and isotherms were examined and parameters were optimized by Minitab software using experimental design method, response surface methodology and Box-Behnken design. The highest capacity of methylene blue adsorption from the aqueous solution obtained at optimal pH of 5, the initial dye concentration of 10 mg/L and an adsorbent amount of 0.03 g was about 54.05 mg/g. Analyzing kinetic data of adsorption experiments confirmed that adsorption process complies with the pseudo-second-order kinetic model. Assessing equilibrium isotherm data at different temperatures showed that these data are in good agreement with Langmuir isotherm model. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of School Belonging Trajectories in Grades 6–8 on Achievement: Gender and Ethnic Differences

PubMed Central

Hughes, Jan N.; Im, Myung Hee; Allee, Paula J.

2015-01-01

This study investigated the association between trajectories of school belonging across grades 6–8 and academic achievement in grade 8 in an ethnically diverse sample of 527 academically at-risk adolescents. Students reported annually on school belonging. Reading and math achievement were assessed at grade 5 (baseline) and grade 8. Interactive effects of gender and ethnicity were found in the conditional growth models for school belonging. Girls of all ethnicities had identical growth trajectories and reported higher initial school belonging than Euro-American or Latino boys. Latino and Euro-American males had lower initial level of school belonging than African American males, and Latino males had lower growth in school belonging than Euro-American males. In structural equation modeling (SEM) analyses, initial level of school belonging predicted grade 8 reading for girls and grade 8 math for boys and girls, above prior achievement and school and child covariates, but growth in school belonging predicted grade 8 achievement only for African American students. Implications for strategies to improve school belonging among academically at-risk youth are discussed. PMID:26563601

Design, characterization and evaluation of hydroxyethylcellulose based novel regenerable supersorbent for heavy metal ions uptake and competitive adsorption.

PubMed

Abbas, Azhar; Hussain, Muhammad Ajaz; Sher, Muhammad; Irfan, Muhammad Imran; Tahir, Muhammad Nawaz; Tremel, Wolfgang; Hussain, Syed Zajif; Hussain, Irshad

2017-09-01

Hydroxyethylcellulose succinate-Na (HEC-Suc-Na) was designed and evaluated for removal of some heavy metal ions from aqueous solution. Pristine sorbent HEC-Suc-Na was thoroughly characterized by FTIR and solid-state CP/MAS 13 C NMR spectroscopy, SEM-EDS and zero point charge analyses. Langmuir isotherm, pseudo second order kinetic and ion exchange models provided best fit to the experimental data of sorption of metal ions. Maximum sorption capacities of supersorbent HEC-Suc-Na for sorption of heavy metal ions from aqueous solution as calculated by Langmuir isotherm model were found to be 1000, 909.09, 666.6, 588 and 500mgg -1 for Pb(II), Cr(VI), Co(II), Cu(II) and Ni(II), respectively. Competitive sorption of these heavy metal ions was carried out from galvanic and nuclear waste water simulated environment. The negative values of ΔG° and ΔH° indicated spontaneity and exothermic nature of sorption. The sorbent was efficiently regenerated with no significant decrease in sorption capacity after five cycles. Copyright © 2017 Elsevier B.V. All rights reserved.

DebriSat Laboratory Analyses

DTIC Science & Technology

2015-01-05

droplets. Fluorine from Teflon wire insulation was also common in the SEM stub and witness plates deposits. Nano droplets of metallic materials...and Debris-LV debris. Aluminum was from the Al honeycomb, nadir and zenith panels, structural core and COPV liner. Aluminum oxide particles were...three pieces: Outer Nylon shell (sabot) with 2 part hollow aluminum insert. • ~600 grams, 8.6 cm diameter X 10.3 cm long – size of a soup can

Mechanical-chemical analyses and sub-chronic systemic toxicity of chemical treated organic bovine bone.

PubMed

Lee, Kwang-il; Lee, Jung-soo; Lee, Keun-soo; Jung, Hong-hee; Ahn, Chan-min; Kim, Young-sik; Shim, Young-bock; Jang, Ju-woong

2015-12-01

Sequentially chemical-treated bovine bone was not only evaluated by mechanical and chemical analyses but also implanted into the gluteal muscles of rats for 12 weeks to investigate potential local pathological effects and systemic toxicities. The test (chemical treated bone) and control (heat treated bone) materials were compared using scanning electron microscope (SEM), x-ray diffraction pattern, inductively coupled plasma analysis, and bending strength test. In the SEM images, the micro-porous structure of heat-treated bone was changed to sintered ceramic-like structure. The structure of bone mineral from test and control materials was analyzed as100% hydroxyapatite. The ratio of calcium (Ca) to potassium (P), the main inorganic elements, was same even though the Ca and P percentages of the control material was relatively higher than the test material. No death or critical symptoms arose from implantation of the test (chemical treated bone) and control (physiological saline) materials during 12 weeks. The implanted sites were macroscopically examined, with all the groups showing non-irritant results. Our results indicate that chemical processed bovine bone has a better mechanical property than the heat treated bone and the implantation of this material does not produce systemic or pathological toxicity. Copyright © 2015 Elsevier Inc. All rights reserved.

Metastable phase in binary and ternary 12-carat gold alloys at low temperature

NASA Astrophysics Data System (ADS)

Lamiri, Imene; Abdelbaky, Mohammed S. M.; Hamana, Djamel; García-Granda, Santiago

2018-04-01

Low temperature phase transitions in 12-carat gold alloys have been investigated for binary Au-Cu and ternary Au-Cu-Ag compositions. The thermal analyses investigations using differential scanning calorimetry (DSC) and the dilatometry were performed in the 50–300 °C temperature range in order to detect the structural transformations. The thermal analyses were carried out on annealed samples at 700 °C for two hour followed by water quenching. They reveal an important new reaction for both used compositions and both thermal techniques confirm each other. This reaction has been assessed as pre-ordering reaction. SEM and STM imaging were performed on annealed samples at 700 °C for two hours and water quenched followed by a heating from room temperature up to the temperature of the new peaks obtained in the thermal study. The imaging reveals the relationship between the pre-ordering reaction and the surface aspect presented in the fact of dendrite precipitates. A series of SEM observation have been performed in order to follow the kinetic of the observed precipitates by the way of several series of heating up, from 140 to 220 °C for the binary composition and from 100 to 180 °C for the ternary composition. Furthermore, this study shows that the silver accelerates the ordering reaction.

Three-dimensional ultrastructural analyses of anterior pituitary gland expose spatial relationships between endocrine cell secretory granule localization and capillary distribution.

PubMed

Yoshitomi, Munetake; Ohta, Keisuke; Kanazawa, Tomonoshin; Togo, Akinobu; Hirashima, Shingo; Uemura, Kei-Ichiro; Okayama, Satoko; Morioka, Motohiro; Nakamura, Kei-Ichiro

2016-10-31

Endocrine and endothelial cells of the anterior pituitary gland frequently make close appositions or contacts, and the secretory granules of each endocrine cell tend to accumulate at the perivascular regions, which is generally considered to facilitate secretory functions of these cells. However, three-dimensional relationships between the localization pattern of secretory granules and blood vessels are not fully understood. To define and characterize these spatial relationships, we used scanning electron microscopy (SEM) three-dimensional reconstruction method based on focused ion-beam slicing and scanning electron microscopy (FIB/SEM). Full three-dimensional cellular architectures of the anterior pituitary tissue at ultrastructural resolution revealed that about 70% of endocrine cells were in apposition to the endothelial cells, while almost 30% of endocrine cells were entirely isolated from perivascular space in the tissue. Our three-dimensional analyses also visualized the distribution pattern of secretory granules in individual endocrine cells, showing an accumulation of secretory granules in regions in close apposition to the blood vessels in many cases. However, secretory granules in cells isolated from the perivascular region tended to distribute uniformly in the cytoplasm of these cells. These data suggest that the cellular interactions between the endocrine and endothelial cells promote an uneven cytoplasmic distribution of the secretory granules.

Silicifying Biofilm Exopolymers on a Hot-Spring Microstromatolite: Templating Nanometer-Thick Laminae

NASA Astrophysics Data System (ADS)

Handley, Kim M.; Turner, Sue J.; Campbell, Kathleen A.; Mountain, Bruce W.

2008-08-01

Exopolymeric substances (EPS) are an integral component of microbial biofilms; however, few studies have addressed their silicification and preservation in hot-spring deposits. Through comparative analyses with the use of a range of microscopy techniques, we identified abundant EPS significant to the textural development of spicular, microstromatolitic, siliceous sinter at Champagne Pool, Waiotapu, New Zealand. Examination of biofilms coating sinter surfaces by confocal laser scanning microscopy (CLSM), environmental scanning electron microscopy (ESEM), cryo-scanning electron microscopy (cryo-SEM), and transmission electron microscopy (TEM) revealed contraction of the gelatinous EPS matrix into films (approximately 10 nm thick) or fibrillar structures, which is common in conventional SEM analyses and analogous to products of naturally occurring desiccation. Silicification of fibrillar EPS contributed to the formation of filamentous sinter. Matrix surfaces or dehydrated films templated sinter laminae (nanometers to microns thick) that, in places, preserved fenestral voids beneath. Laminae of similar thickness are, in general, common to spicular geyserites. This is the first report to demonstrate EPS templation of siliceous stromatolite laminae. Considering the ubiquity of biofilms on surfaces in hot-spring environments, EPS silicification studies are likely to be important to a better understanding of the origins of laminae in other modern and ancient stromatolitic sinters, and EPS potentially may serve as biosignatures in extraterrestrial rocks.

Stable superhydrophilic coating on superhydrophobic porous media by functionalized nanoparticles

NASA Astrophysics Data System (ADS)

Khazaei, Masoud; Taghi Sadeghi, Mohammad; Sadat Hosseini, Marzieh

2018-01-01

In this study, the hydrophilicity property of TiO2 nano-coating was improved by zinc acetate-assisted sol-gel method. The stable superhydrophilic coating was fabricated on a superhydrophobic mineral rock surface. The wettability of surface before and after coating was characterized by contact angle measurements. The n-heptane and water droplet contact angle was 0° and 168° respectively, so the untreated rock was superhydrophobic. After nano-treatment, the n-heptane and water contact angle changed to 172° and 0° respectively, so the superhydrophilic coating was formed on the superhydrophobic surface. The thermal, mechanical and salinity stability of the fabricated coatings was investigated. The coatings had high thermal and salinity stability; they also had moderate mechanical stability that was evaluated by abrasion test. The morphology and composition of synthesized nanoparticles were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy and x-ray diffraction (XRD) analyses. Characterization of the coated surfaces was conducted by SEM and XRD analyses. Applications of these nano-coatings include surfaces where cleanliness is paramount such as in hospitals as well as the protection of public monuments and building facades from weathering. Novel industrial application includes wettability alteration of oil wet carbonate rock for enhanced oil recovery.

Electron Microscopic Analysis of Surface Inorganic Substances on Oral and Combustible Tobacco Products

PubMed Central

Halstead, Mary M.; Watson, Clifford H.; Pappas, R. Steven

2015-01-01

Though quantitative trace toxic metals analyses have been performed on tobacco products, little has been published on inorganic particulate constituents on and inside the products. We analyzed these constituents using scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM-EDS). The nature of SEM-EDS instrumentation makes it an ideal choice for inorganic particulate analyses and yields relevant information to potential exposures during consumption of oral tobacco products, and possibly as a consequence of smoking. Aluminum silicates, silica, and calcium compounds were common inorganic particulate constituents of tobacco products. Aluminum silicates and silica from soil were found on external leaf surfaces. Phytolithic silica, found in the lumen of the plant leaf, is of biogenic origin. Calcium oxalate was also apparently of biogenic origin. Small mineral deposits on tobacco could have health implications. Minerals found on the surfaces of smokeless tobacco products could possibly abrade the oral mucosa and contribute to the oral inflammatory responses observed with smokeless tobacco product use. If micron and sub-micron size calcium particles on cigarette filler were transported in mainstream smoke, they could potentially induce a pulmonary irritant inflammation when inhaled. The transport of aluminum silicate and silica in smoke could potentially also contribute to chronic inflammatory disease. PMID:26286581

Electrical Characteristics CuFe2O4 Thick Film Ceramics Made with Different Screen Size Utiizing Fe2O3 Nanopowder Derived from Yarosite for NTC Thermistor

NASA Astrophysics Data System (ADS)

Wiendartun, Syarif, Dani Gustaman

2010-10-01

Fabrication of CuFe2O4 thick film ceramics utilizing Fe2O3 derived from yarosite using screen printing technique for NTC thermistor has been carried out. Effect of thickness variation due to different size of screen (screen 225; 300 and 375 mesh) has been studied. X-ray diffraction analyses (XRD) was done to know crystal structure and phases formation. SEM analyses was carried out to know microstructure of the films. Electrical properties characterization was done through measurement of electrical resistance at various temperatures (room temperature to 100° C). The XRD data showed that the films crystalize in tetragonal spinel. The SEM images showed that the screen with the smaller of the hole size, made the grain size was bigger. Electrical data showed that the larger the screen different size thickness variation (mesh), the larger the resistance, thermistor constant and sensitivity. From the electrical characteristics data, it was known that the electrical characteristics of the CuFe2O4 thick film ceramics followed the NTC characteristic. The value of B and RRT of the produced CuFe2O4 ceramics namely B = 3241-3484 K and RRT = 25.6-87.0 M Ohm, fitted market requirement.

Sexually Explicit Media Use by Sexual Identity: A Comparative Analysis of Gay, Bisexual, and Heterosexual Men in the United States.

PubMed

Downing, Martin J; Schrimshaw, Eric W; Scheinmann, Roberta; Antebi-Gruszka, Nadav; Hirshfield, Sabina

2017-08-01

Advances in production and distribution of sexually explicit media (SEM) online have resulted in widespread use among men. Limited research has compared contexts of use and behaviors viewed in Internet SEM by sexual identity. The current study examined differences in recent SEM use (past 6 months) by sexual identity among an ethnically diverse sample of 821 men who completed an online survey in 2015. Both gay and bisexual men reported significantly more frequent use of Internet SEM compared to heterosexual men. Although most participants reported viewing SEM at home (on a computer, tablet, or smartphone), significantly more gay men reported SEM use at a sex party or commercial sex venue than either heterosexual or bisexual men. Sexual identity predicted viewing of high-risk and protective behaviors in separate logistic regression models. Specifically, compared to heterosexual men, gay and bisexual men had increased odds of viewing condomless anal sex (gay OR 5.20, 95 % CI 3.35-8.09; bisexual OR 3.99, 95 % CI 2.24-7.10) and anal sex with a condom (gay OR 3.93, 95 % CI 2.64-5.83; bisexual OR 4.59, 95 % CI 2.78-7.57). Compared to gay men, heterosexual and bisexual men had increased odds of viewing condomless vaginal sex (heterosexual OR 27.08, 95 % CI 15.25-48.07; bisexual OR 5.59, 95 % CI 3.81-8.21) and vaginal sex with a condom (heterosexual OR 7.90, 95 % CI 5.19-12.03; bisexual OR 4.97, 95 % CI 3.32-7.44). There was also evidence of identity discrepant SEM viewing as 20.7 % of heterosexual-identified men reported viewing male same-sex behavior and 55.0 % of gay-identified men reported viewing heterosexual behavior. Findings suggest the importance of assessing SEM use across media types and contexts and have implications for research to address the potential influence of SEM on sexual behavior (e.g., investigate associations between viewing condomless vaginal sex and engaging in high-risk encounters with female partners).

Field emission scanning electron microscopy (FE-SEM) as an approach for nanoparticle detection inside cells.

PubMed

Havrdova, M; Polakova, K; Skopalik, J; Vujtek, M; Mokdad, A; Homolkova, M; Tucek, J; Nebesarova, J; Zboril, R

2014-12-01

When developing new nanoparticles for bio-applications, it is important to fully characterize the nanoparticle's behavior in biological systems. The most common techniques employed for mapping nanoparticles inside cells include transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). These techniques entail passing an electron beam through a thin specimen. STEM or TEM imaging is often used for the detection of nanoparticles inside cellular organelles. However, lengthy sample preparation is required (i.e., fixation, dehydration, drying, resin embedding, and cutting). In the present work, a new matrix (FTO glass) for biological samples was used and characterized by field emission scanning electron microscopy (FE-SEM) to generate images comparable to those obtained by TEM. Using FE-SEM, nanoparticle images were acquired inside endo/lysosomes without disruption of the cellular shape. Furthermore, the initial steps of nanoparticle incorporation into the cells were captured. In addition, the conductive FTO glass endowed the sample with high stability under the required accelerating voltage. Owing to these features of the sample, further analyses could be performed (material contrast and energy-dispersive X-ray spectroscopy (EDS)), which confirmed the presence of nanoparticles inside the cells. The results showed that FE-SEM can enable detailed characterization of nanoparticles in endosomes without the need for contrast staining or metal coating of the sample. Images showing the intracellular distribution of nanoparticles together with cellular morphology can give important information on the biocompatibility and demonstrate the potential of nanoparticle utilization in medicine. Copyright © 2014 Elsevier Ltd. All rights reserved.

Characterisation of heavy metal-bearing phases in stream sediments of the Meža River Valley, Slovenia, by means of SEM/EDS analysis

NASA Astrophysics Data System (ADS)

Miler, M.; Gosar, M.

2010-02-01

Stream sediment reflects the rock structure of the catchment area, its geochemical characteristics and possible recent contamination upstream of the sampling point and thus, it is most frequently used in geochemical researches of heavy metal pollution. Stream sediment samples were collected along the Meža River and its tributaries and the Drava River, located in the NNE part of Slovenia. Previous geochemical studies have shown that these sediments are heavily polluted with heavy metals as a consequence of past mining of Pb-Zn ore and steelworks activities. Conventional geochemical analyses (ICP-MS, AAS, etc.) provided limited information on mineralogy, morphology and sources of heavy metal-bearing phases therefore SEM/EDS was utilized. Several problems were confronted with during EDS analysis, which are related to identification and quantification of light elements, identification of elements due to peak overlaps and quantification of spectra from unpolished samples. These problems were successfully dealt with. SEM/EDS enabled successful identification of heavy metal-bearing phases in stream sediments. Ore mineral phases, such as cerussite, sphalerite, smithsonite and galena, different heavy metal-bearing Fe-alloys, Fe-oxides and spherical particles and common rock-forming and accessory mineral phases, such as barite, rutile, ilmenite, zircon and monazite, were identified using solely SEM/EDS. These results were used for subsequent geochemical interpretation and source apportionment of heavy metals, according to associations of different heavy metal-bearing phases. Heavy metal-bearing phases were arranged by their source and genesis into three groups, denoted as geogenic/technogenic, technogenic and geogenic.

Opposing Effects of Semantic Diversity in Lexical and Semantic Relatedness Decisions

PubMed Central

2015-01-01

Semantic ambiguity has often been divided into 2 forms: homonymy, referring to words with 2 unrelated interpretations (e.g., bark), and polysemy, referring to words associated with a number of varying but semantically linked uses (e.g., twist). Typically, polysemous words are thought of as having a fixed number of discrete definitions, or “senses,” with each use of the word corresponding to one of its senses. In this study, we investigated an alternative conception of polysemy, based on the idea that polysemous variation in meaning is a continuous, graded phenomenon that occurs as a function of contextual variation in word usage. We quantified this contextual variation using semantic diversity (SemD), a corpus-based measure of the degree to which a particular word is used in a diverse set of linguistic contexts. In line with other approaches to polysemy, we found a reaction time (RT) advantage for high SemD words in lexical decision, which occurred for words of both high and low imageability. When participants made semantic relatedness decisions to word pairs, however, responses were slower to high SemD pairs, irrespective of whether these were related or unrelated. Again, this result emerged irrespective of the imageability of the word. The latter result diverges from previous findings using homonyms, in which ambiguity effects have only been found for related word pairs. We argue that participants were slower to respond to high SemD words because their high contextual variability resulted in noisy, underspecified semantic representations that were more difficult to compare with one another. We demonstrated this principle in a connectionist computational model that was trained to activate distributed semantic representations from orthographic inputs. Greater variability in the orthography-to-semantic mappings of high SemD words resulted in a lower degree of similarity for related pairs of this type. At the same time, the representations of high SemD unrelated pairs were less distinct from one another. In addition, the model demonstrated more rapid semantic activation for high SemD words, thought to underpin the processing advantage in lexical decision. These results support the view that polysemous variation in word meaning can be conceptualized in terms of graded variation in distributed semantic representations. PMID:25751041