32 CFR 644.411 - Form of inter-agency transfer instrument.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 4 2010-07-01 2010-07-01 true Form of inter-agency transfer instrument. 644.411 Section 644.411 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY (CONTINUED) REAL... of the Secretary of the transferring department and will be addressed to the Secretary of head of the...

Analysis of variance to assess statistical significance of Laplacian estimation accuracy improvement due to novel variable inter-ring distances concentric ring electrodes.

PubMed

Makeyev, Oleksandr; Joe, Cody; Lee, Colin; Besio, Walter G

2017-07-01

Concentric ring electrodes have shown promise in non-invasive electrophysiological measurement demonstrating their superiority to conventional disc electrodes, in particular, in accuracy of Laplacian estimation. Recently, we have proposed novel variable inter-ring distances concentric ring electrodes. Analytic and finite element method modeling results for linearly increasing distances electrode configurations suggested they may decrease the truncation error resulting in more accurate Laplacian estimates compared to currently used constant inter-ring distances configurations. This study assesses statistical significance of Laplacian estimation accuracy improvement due to novel variable inter-ring distances concentric ring electrodes. Full factorial design of analysis of variance was used with one categorical and two numerical factors: the inter-ring distances, the electrode diameter, and the number of concentric rings in the electrode. The response variables were the Relative Error and the Maximum Error of Laplacian estimation computed using a finite element method model for each of the combinations of levels of three factors. Effects of the main factors and their interactions on Relative Error and Maximum Error were assessed and the obtained results suggest that all three factors have statistically significant effects in the model confirming the potential of using inter-ring distances as a means of improving accuracy of Laplacian estimation.

QIVIVE Approaches to Evaluate Inter-individual Toxicokinetic Variability

EPA Science Inventory

Manifestation of inter-individual variability in toxicokinetics (TK) will result in identical external exposure concentrations yielding differing blood or tissue concentrations. As efforts to incorporate in vitro testing strategies into human health assessment continue to grow, a...

Finite element method modeling to assess Laplacian estimates via novel variable inter-ring distances concentric ring electrodes.

PubMed

Makeyev, Oleksandr; Besio, Walter G

2016-08-01

Noninvasive concentric ring electrodes are a promising alternative to conventional disc electrodes. Currently, superiority of tripolar concentric ring electrodes over disc electrodes, in particular, in accuracy of Laplacian estimation has been demonstrated in a range of applications. In our recent work we have shown that accuracy of Laplacian estimation can be improved with multipolar concentric ring electrodes using a general approach to estimation of the Laplacian for an (n + 1)-polar electrode with n rings using the (4n + 1)-point method for n ≥ 2. This paper takes the next step toward further improving the Laplacian estimate by proposing novel variable inter-ring distances concentric ring electrodes. Derived using a modified (4n + 1)-point method, linearly increasing and decreasing inter-ring distances tripolar (n = 2) and quadripolar (n = 3) electrode configurations are compared to their constant inter-ring distances counterparts using finite element method modeling. Obtained results suggest that increasing inter-ring distances electrode configurations may decrease the estimation error resulting in more accurate Laplacian estimates compared to respective constant inter-ring distances configurations. For currently used tripolar electrode configuration the estimation error may be decreased more than two-fold while for the quadripolar configuration more than six-fold decrease is expected.

Inter- and intraobserver variability of (semi-)quantitative parameters commonly used in feline thyroid scintigraphy.

PubMed

Volckaert, Veerle; Vandermeulen, Eva; Duchateau, Luc; Saunders, Jimmy H; Peremans, Kathelijne

2016-04-01

The aim of this study was to assess inter- and intraobserver variability of commonly used semi-quantitative and quantitative parameters in feline thyroid scintigraphy: thyroid to salivary gland ratio (T/S), thyroid to background ratio (T/B) and the percentage technetium pertechnetate uptake for the thyroid glands (%TcUT). These parameters are being used to diagnose thyroid disease and to assess its severity, but may be influenced by operator related factors when processing the images. Additionally, inter- and intraobserver variability of the percentage technetium pertechnetate uptake for the salivary glands was determined (%TcUSG). The study included technetium pertechnetate scans of 100 hyperthyroid cats. Variability within and between three observers was determined using a random effects model and variance components were estimated by the restricted maximum likelihood procedure. The %TcU for the thyroid and salivary glands, as well as the T/S ratio, showed little to no difference in inter- and intraobserver variability, whereas this was clearly present for the T/B ratio. Overall, the T/S ratio and %TcUSG showed a good repeatability and reproducibility with low inter- and intraobserver variabilities. Inter- and intraobserver variability was higher for the %TcUT, however variations were still considered to be acceptable. On the contrary, inter- and intraobserver variability was clearly larger for the T/B ratio. These findings suggest the preferential use of the T/S ratio or %TcU, especially in facilities with a less experienced staff. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Linking Inter-Individual Variability in Functional Brain Connectivity to Cognitive Ability in Elderly Individuals

PubMed Central

Li, Rui; Yin, Shufei; Zhu, Xinyi; Ren, Weicong; Yu, Jing; Wang, Pengyun; Zheng, Zhiwei; Niu, Ya-Nan; Huang, Xin; Li, Juan

2017-01-01

Increasing evidence suggests that functional brain connectivity is an important determinant of cognitive aging. However, the fundamental concept of inter-individual variations in functional connectivity in older individuals is not yet completely understood. It is essential to evaluate the extent to which inter-individual variability in connectivity impacts cognitive performance at an older age. In the current study, we aimed to characterize individual variability of functional connectivity in the elderly and to examine its significance to individual cognition. We mapped inter-individual variability of functional connectivity by analyzing whole-brain functional connectivity magnetic resonance imaging data obtained from a large sample of cognitively normal older adults. Our results demonstrated a gradual increase in variability in primary regions of the visual, sensorimotor, and auditory networks to specific subcortical structures, particularly the hippocampal formation, and the prefrontal and parietal cortices, which largely constitute the default mode and fronto-parietal networks, to the cerebellum. Further, the inter-individual variability of the functional connectivity correlated significantly with the degree of cognitive relevance. Regions with greater connectivity variability demonstrated more connections that correlated with cognitive performance. These results also underscored the crucial function of the long-range and inter-network connections in individual cognition. Thus, individual connectivity–cognition variability mapping findings may provide important information for future research on cognitive aging and neurocognitive diseases. PMID:29209203

Scaling functional status within the interRAI suite of assessment instruments

PubMed Central

2013-01-01

Background As one ages, physical, cognitive, and clinical problems accumulate and the pattern of loss follows a distinct progression. The first areas requiring outside support are the Instrumental Activities of Daily Living and over time there is a need for support in performing the Activities of Daily Living. Two new functional hierarchies are presented, an IADL hierarchical capacity scale and a combination scale integrating both IADL and ADL hierarchies. Methods A secondary analyses of data from a cross-national sample of community residing persons was conducted using 762,023 interRAI assessments. The development of the new IADL Hierarchy and a new IADL-ADL combined scale proceeded through a series of interrelated steps first examining individual IADL and ADL item scores among persons receiving home care and those living independently without services. A factor analysis demonstrated the overall continuity across the IADL-ADL continuum. Evidence of the validity of the scales was explored with associative analyses of factors such as a cross-country distributional analysis for persons in home care programs, a count of functional problems across the categories of the hierarchy, an assessment of the hours of informal and formal care received each week by persons in the different categories of the hierarchy, and finally, evaluation of the relationship between cognitive status and the hierarchical IADL-ADL assignments. Results Using items from interRAI’s suite of assessment instruments, two new functional scales were developed, the interRAI IADL Hierarchy Scale and the interRAI IADL-ADL Functional Hierarchy Scale. The IADL Hierarchy Scale consisted of 5 items, meal preparation, housework, shopping, finances and medications. The interRAI IADL-ADL Functional Hierarchy Scale was created through an amalgamation of the ADL Hierarchy (developed previously) and IADL Hierarchy Scales. These scales cover the spectrum of IADL and ADL challenges faced by persons in the community

Technical aspects and inter-laboratory variability in native peptide profiling: the CE-MS experience.

PubMed

Mischak, Harald; Vlahou, Antonia; Ioannidis, John P A

2013-04-01

Mass spectrometry platforms have attracted a lot of interest in the last 2 decades as profiling tools for native peptides and proteins with clinical potential. However, limitations associated with reproducibility and analytical robustness, especially pronounced with the initial SELDI systems, hindered the application of such platforms in biomarker qualification and clinical implementation. The scope of this article is to give a short overview on data available on performance and on analytical robustness of the different platforms for peptide profiling. Using the CE-MS platform as a paradigm, data on analytical performance are described including reproducibility (short-term and intermediate repeatability), stability, interference, quantification capabilities (limits of detection), and inter-laboratory variability. We discuss these issues by using as an example our experience with the development of a 273-peptide marker for chronic kidney disease. Finally, we discuss pros and cons and means for improvement and emphasize the need to test in terms of comparative clinical performance and impact, different platforms that pass reasonably well analytical validation tests. Copyright © 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Instrumental variable methods in comparative safety and effectiveness research.

PubMed

Brookhart, M Alan; Rassen, Jeremy A; Schneeweiss, Sebastian

2010-06-01

Instrumental variable (IV) methods have been proposed as a potential approach to the common problem of uncontrolled confounding in comparative studies of medical interventions, but IV methods are unfamiliar to many researchers. The goal of this article is to provide a non-technical, practical introduction to IV methods for comparative safety and effectiveness research. We outline the principles and basic assumptions necessary for valid IV estimation, discuss how to interpret the results of an IV study, provide a review of instruments that have been used in comparative effectiveness research, and suggest some minimal reporting standards for an IV analysis. Finally, we offer our perspective of the role of IV estimation vis-à-vis more traditional approaches based on statistical modeling of the exposure or outcome. We anticipate that IV methods will be often underpowered for drug safety studies of very rare outcomes, but may be potentially useful in studies of intended effects where uncontrolled confounding may be substantial.

Instrumental variable methods in comparative safety and effectiveness research†

PubMed Central

Brookhart, M. Alan; Rassen, Jeremy A.; Schneeweiss, Sebastian

2010-01-01

Summary Instrumental variable (IV) methods have been proposed as a potential approach to the common problem of uncontrolled confounding in comparative studies of medical interventions, but IV methods are unfamiliar to many researchers. The goal of this article is to provide a non-technical, practical introduction to IV methods for comparative safety and effectiveness research. We outline the principles and basic assumptions necessary for valid IV estimation, discuss how to interpret the results of an IV study, provide a review of instruments that have been used in comparative effectiveness research, and suggest some minimal reporting standards for an IV analysis. Finally, we offer our perspective of the role of IV estimation vis-à-vis more traditional approaches based on statistical modeling of the exposure or outcome. We anticipate that IV methods will be often underpowered for drug safety studies of very rare outcomes, but may be potentially useful in studies of intended effects where uncontrolled confounding may be substantial. PMID:20354968

Drivers of inter-year variability of plant production and decomposers across contrasting island ecosystems.

PubMed

Wardle, David A; Jonsson, Micael; Kalela-Brundin, Maarit; Lagerström, Anna; Bardgett, Richard D; Yeates, Gregor W; Nilsson, Marie-Charlotte

2012-03-01

Despite the likely importance of inter-year dynamics of plant production and consumer biota for driving community- and ecosystem-level processes, very few studies have explored how and why these dynamics vary across contrasting ecosystems. We utilized a well-characterized system of 30 lake islands in the boreal forest zone of northern Sweden across which soil fertility and productivity vary considerably, with larger islands being more fertile and productive than smaller ones. In this system we assessed the inter-year dynamics of several measures of plant production and the soil microbial community (primary consumers in the decomposer food web) for each of nine years, and soil microfaunal groups (secondary and tertiary consumers) for each of six of those years. We found that, for measures of plant production and each of the three consumer trophic levels, inter-year dynamics were strongly affected by island size. Further, many variables were strongly affected by island size (and thus bottom-up regulation by soil fertility and resources) in some years, but not in other years, most likely due to inter-year variation in climatic conditions. For each of the plant and microbial variables for which we had nine years of data, we also determined the inter-year coefficient of variation (CV), an inverse measure of stability. We found that CVs of some measures of plant productivity were greater on large islands, whereas those of other measures were greater on smaller islands; CVs of microbial variables were unresponsive to island size. We also found that the effects of island size on the temporal dynamics of some variables were related to inter-year variability of macroclimatic variables. As such, our results show that the inter-year dynamics of both plant productivity and decomposer biota across each of three trophic levels, as well as the inter-year stability of plant productivity, differ greatly across contrasting ecosystems, with potentially important but largely overlooked

Power calculator for instrumental variable analysis in pharmacoepidemiology

PubMed Central

Walker, Venexia M; Davies, Neil M; Windmeijer, Frank; Burgess, Stephen; Martin, Richard M

2017-01-01

Abstract Background Instrumental variable analysis, for example with physicians’ prescribing preferences as an instrument for medications issued in primary care, is an increasingly popular method in the field of pharmacoepidemiology. Existing power calculators for studies using instrumental variable analysis, such as Mendelian randomization power calculators, do not allow for the structure of research questions in this field. This is because the analysis in pharmacoepidemiology will typically have stronger instruments and detect larger causal effects than in other fields. Consequently, there is a need for dedicated power calculators for pharmacoepidemiological research. Methods and Results The formula for calculating the power of a study using instrumental variable analysis in the context of pharmacoepidemiology is derived before being validated by a simulation study. The formula is applicable for studies using a single binary instrument to analyse the causal effect of a binary exposure on a continuous outcome. An online calculator, as well as packages in both R and Stata, are provided for the implementation of the formula by others. Conclusions The statistical power of instrumental variable analysis in pharmacoepidemiological studies to detect a clinically meaningful treatment effect is an important consideration. Research questions in this field have distinct structures that must be accounted for when calculating power. The formula presented differs from existing instrumental variable power formulae due to its parametrization, which is designed specifically for ease of use by pharmacoepidemiologists. PMID:28575313

76 FR 323 - Sensors and Instrumentation Technical Advisory Committee; Notice of Partially Closed Meeting

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Inter-individual cognitive variability in children with Asperger's syndrome

PubMed Central

Gonzalez-Gadea, Maria Luz; Tripicchio, Paula; Rattazzi, Alexia; Baez, Sandra; Marino, Julian; Roca, Maria; Manes, Facundo; Ibanez, Agustin

2014-01-01

Multiple studies have tried to establish the distinctive profile of individuals with Asperger's syndrome (AS). However, recent reports suggest that adults with AS feature heterogeneous cognitive profiles. The present study explores inter-individual variability in children with AS through group comparison and multiple case series analysis. All participants completed an extended battery including measures of fluid and crystallized intelligence, executive functions, theory of mind, and classical neuropsychological tests. Significant group differences were found in theory of mind and other domains related to global information processing. However, the AS group showed high inter-individual variability (both sub- and supra-normal performance) on most cognitive tasks. Furthermore, high fluid intelligence correlated with less general cognitive impairment, high cognitive flexibility, and speed of motor processing. In light of these findings, we propose that children with AS are characterized by a distinct, uneven pattern of cognitive strengths and weaknesses. PMID:25132817

Tutorial in Biostatistics: Instrumental Variable Methods for Causal Inference*

PubMed Central

Baiocchi, Michael; Cheng, Jing; Small, Dylan S.

2014-01-01

A goal of many health studies is to determine the causal effect of a treatment or intervention on health outcomes. Often, it is not ethically or practically possible to conduct a perfectly randomized experiment and instead an observational study must be used. A major challenge to the validity of observational studies is the possibility of unmeasured confounding (i.e., unmeasured ways in which the treatment and control groups differ before treatment administration which also affect the outcome). Instrumental variables analysis is a method for controlling for unmeasured confounding. This type of analysis requires the measurement of a valid instrumental variable, which is a variable that (i) is independent of the unmeasured confounding; (ii) affects the treatment; and (iii) affects the outcome only indirectly through its effect on the treatment. This tutorial discusses the types of causal effects that can be estimated by instrumental variables analysis; the assumptions needed for instrumental variables analysis to provide valid estimates of causal effects and sensitivity analysis for those assumptions; methods of estimation of causal effects using instrumental variables; and sources of instrumental variables in health studies. PMID:24599889

Staging Sleep in Polysomnograms: Analysis of Inter-Scorer Variability

PubMed Central

Younes, Magdy; Raneri, Jill; Hanly, Patrick

2016-01-01

Study Objectives: To determine the reasons for inter-scorer variability in sleep staging of polysomnograms (PSGs). Methods: Fifty-six PSGs were scored (5-stage sleep scoring) by 2 experienced technologists, (first manual, M1). Months later, the technologists edited their own scoring (second manual, M2) based upon feedback from the investigators that highlighted differences between their scoring. The PSGs were then scored with an automatic system (Auto) and the technologists edited them, epoch-by-epoch (Edited-Auto). This resulted in 6 different manual scores for each PSG. Epochs were classified as scorer errors (one M1 score differed from the other 5 scores), scorer bias (all 3 scores of each technologist were similar, but differed from the other technologist) and equivocal (sleep scoring was inconsistent within and between technologists). Results: Percent agreement after M1 was 78.9% ± 9.0% and was unchanged after M2 (78.1% ± 9.7%) despite numerous edits (≈40/PSG) by the scorers. Agreement in Edited-Auto was higher (86.5% ± 6.4%, p < 1E−9). Scorer errors (< 2% of epochs) and scorer bias (3.5% ± 2.3% of epochs) together accounted for < 20% of M1 disagreements. A large number of epochs (92 ± 44/PSG) with scoring agreement in M1 were subsequently changed in M2 and/or Edited-Auto. Equivocal epochs, which showed scoring inconsistency, accounted for 28% ± 12% of all epochs, and up to 76% of all epochs in individual patients. Disagreements were largely between awake/NREM, N1/N2, and N2/N3 sleep. Conclusion: Inter-scorer variability is largely due to epochs that are difficult to classify. Availability of digitally identified events (e.g., spindles) or calculated variables (e.g., depth of sleep, delta wave duration) during scoring may greatly reduce scoring variability. Citation: Younes M, Raneri J, Hanly P. Staging sleep in polysomnograms: analysis of inter-scorer variability. J Clin Sleep Med 2016;12(6):885–894. PMID:27070243

Does using the interRAI Palliative Care instrument reduce the needs and symptoms of nursing home residents receiving palliative care?

PubMed

Hermans, Kirsten; De Almeida Mello, Johanna; Spruytte, Nele; Cohen, Joachim; Van Audenhove, Chantal; Declercq, Anja

2018-02-01

This study aimed to evaluate whether using the interRAI Palliative Care instrument (the interRAI PC) in nursing homes is associated with reduced needs and symptoms in residents nearing the end of their lives. A quasi-experimental pretest-posttest study using the Palliative care Outcome Scale (POS) was conducted to compare the needs and symptoms of residents nearing the end of their lives in the control and intervention nursing homes. Care professionals at the intervention nursing homes filled out the interRAI PC over the course of a year for all residents aged 65 years and older who were nearing the end of their lives. This intervention was not implemented in the control nursing homes. At baseline, POS scores in the intervention nursing homes were lower (more favorable) than in the control nursing homes on the items "pain", "other symptoms", "family anxiety", and the total POS score. Posttest POS scores for "wasted time" were higher (less favorable) than pretest scores in the intervention nursing homes. In the intervention nursing homes where care professionals did not have prior experience with the interRAI Long-Term Care Facilities (LTCF) assessment instrument (n = 8/15), total POS scores were lower (more favorable) at posttest. One year after introducing the interRAI PC, no reduction in residents' needs and symptoms were detected in the intervention nursing homes. However, reductions in needs and symptoms were found in the subgroup of intervention nursing homes without prior experience with the interRAI LTCF instrument. This may suggest that the use of an interRAI instrument other than the interRAI PC specifically can improve care. Future research should aim at replicating this research with a long-term design in order to evaluate the effect of integrating the use of the interRAI PC in the day-to-day practices at nursing homes.

Latent class instrumental variables: a clinical and biostatistical perspective.

PubMed

Baker, Stuart G; Kramer, Barnett S; Lindeman, Karen S

2016-01-15

In some two-arm randomized trials, some participants receive the treatment assigned to the other arm as a result of technical problems, refusal of a treatment invitation, or a choice of treatment in an encouragement design. In some before-and-after studies, the availability of a new treatment changes from one time period to this next. Under assumptions that are often reasonable, the latent class instrumental variable (IV) method estimates the effect of treatment received in the aforementioned scenarios involving all-or-none compliance and all-or-none availability. Key aspects are four initial latent classes (sometimes called principal strata) based on treatment received if in each randomization group or time period, the exclusion restriction assumption (in which randomization group or time period is an instrumental variable), the monotonicity assumption (which drops an implausible latent class from the analysis), and the estimated effect of receiving treatment in one latent class (sometimes called efficacy, the local average treatment effect, or the complier average causal effect). Since its independent formulations in the biostatistics and econometrics literatures, the latent class IV method (which has no well-established name) has gained increasing popularity. We review the latent class IV method from a clinical and biostatistical perspective, focusing on underlying assumptions, methodological extensions, and applications in our fields of obstetrics and cancer research. Copyright © 2015 John Wiley & Sons, Ltd.

Latent class instrumental variables: A clinical and biostatistical perspective

PubMed Central

Baker, Stuart G.; Kramer, Barnett S.; Lindeman, Karen S.

2015-01-01

In some two-arm randomized trials, some participants receive the treatment assigned to the other arm as a result of technical problems, refusal of a treatment invitation, or a choice of treatment in an encouragement design. In some before-and-after studies, the availability of a new treatment changes from one time period to this next. Under assumptions that are often reasonable, the latent class instrumental variable (IV) method estimates the effect of treatment received in the aforementioned scenarios involving all-or-none compliance and all-or-none availability. Key aspects are four initial latent classes (sometimes called principal strata) based on treatment received if in each randomization group or time period, the exclusion restriction assumption (in which randomization group or time period is an instrumental variable), the monotonicity assumption (which drops an implausible latent class from the analysis), and the estimated effect of receiving treatment in one latent class (sometimes called efficacy, the local average treatment effect, or the complier average causal effect). Since its independent formulations in the biostatistics and econometrics literatures, the latent class IV method (which has no well-established name) has gained increasing popularity. We review the latent class IV method from a clinical and biostatistical perspective, focusing on underlying assumptions, methodological extensions, and applications in our fields of obstetrics and cancer research. PMID:26239275

The predicted CLARREO sampling error of the inter-annual SW variability

NASA Astrophysics Data System (ADS)

Doelling, D. R.; Keyes, D. F.; Nguyen, C.; Macdonnell, D.; Young, D. F.

2009-12-01

The NRC Decadal Survey has called for SI traceability of long-term hyper-spectral flux measurements in order to monitor climate variability. This mission is called the Climate Absolute Radiance and Refractivity Observatory (CLARREO) and is currently defining its mission requirements. The requirements are focused on the ability to measure decadal change of key climate variables at very high accuracy. The accuracy goals are set using anticipated climate change magnitudes, but the accuracy achieved for any given climate variable must take into account the temporal and spatial sampling errors based on satellite orbits and calibration accuracy. The time period to detect a significant trend in the CLARREO record depends on the magnitude of the sampling calibration errors relative to the current inter-annual variability. The largest uncertainty in climate feedbacks remains the effect of changing clouds on planetary energy balance. Some regions on earth have strong diurnal cycles, such as maritime stratus and afternoon land convection; other regions have strong seasonal cycles, such as the monsoon. However, when monitoring inter-annual variability these cycles are only important if the strength of these cycles vary on decadal time scales. This study will attempt to determine the best satellite constellations to reduce sampling error and to compare the error with the current inter-annual variability signal to ensure the viability of the mission. The study will incorporate Clouds and the Earth's Radiant Energy System (CERES) (Monthly TOA/Surface Averages) SRBAVG product TOA LW and SW climate quality fluxes. The fluxes are derived by combining Terra (10:30 local equator crossing time) CERES fluxes with 3-hourly 5-geostationary satellite estimated broadband fluxes, which are normalized using the CERES fluxes, to complete the diurnal cycle. These fluxes were saved hourly during processing and considered the truth dataset. 90°, 83° and 74° inclination precessionary orbits as

Inter-individual Differences in Heart Rate Variability Are Associated with Inter-individual Differences in Empathy and Alexithymia.

PubMed

Lischke, Alexander; Pahnke, Rike; Mau-Moeller, Anett; Behrens, Martin; Grabe, Hans J; Freyberger, Harald J; Hamm, Alfons O; Weippert, Matthias

2018-01-01

In the present study, we investigated whether inter-individual differences in vagally mediated heart rate variability (vmHRV) would be associated with inter-individual differences in empathy and alexithymia. To this end, we determined resting state HF-HRV in 90 individuals that also completed questionnaires assessing inter-individual differences in empathy and alexithymia. Our categorical and dimensional analyses revealed that inter-individual differences in HF-HRV were differently associated with inter-individual differences in empathy and alexithymia. We found that individuals with high HF-HRV reported more empathy and less alexithymia than individuals with low HF-HRV. Moreover, we even found that an increase in HF-HRV was associated with an increase in empathy and a decrease in alexithymia across all participants. Taken together, these findings indicate that individuals with high HF-HRV are more empathetic and less alexithymic than individuals with low HF-HRV. These differences in empathy and alexithymia may explain why individuals with high HF-HRV are more successful in sharing and understanding the mental and emotional states of others than individuals with low HF-HRV.

Inter-annual Variability in Tundra Phenology Captured with Digital Photography

NASA Astrophysics Data System (ADS)

Melendez, M.; Vargas, S. A.; Tweedie, C. E.

2012-12-01

The need to improve multi-scale phenological monitoring of arctic terrestrial ecosystems has been a persistent research challenge. Although there has been a range of advances in remote sensing capacities over the past decade, these present costly, and sometimes logistically challenging and technically demanding solutions for arctic terrestrial ecosystems. In this poster and undergraduate research project, we demonstrate how seasonal and inter-annual variability in landscape phenology can be derived for multiple tundra ecosystems using a low-cost and low-tech kite aerial photography (KAP) system that has been developed as a contribution to the US Arctic Observing Network. Seasonal landscape phenology was observed over the Networked Info-Mechanical Systems (NIMS) grids (2 x 50 meters) located in Barrow and Atqasuk, Alaska using imagery acquired with KAP and analyzed for a range of greenness indices. Preliminary results showed that the 2G-RB greenness index correlated the best with NDVI values calculated from ground based hyperspectral reflectance measurements. 2012 had the highest 2G-RB greenness index values for both Barrow and Atqasuk sites, which correlated well with NDVI values acquired from ground-based hyperspectral reflectance measurements. Wet vegetation types showed the most interannual variability at the Atqasuk site based on the 2G-RB greenness index while in Barrow the moist vegetation types showed the most interannual variability. These results show that vegetation indices similar to those acquired from hyperspectral remote sensing platforms can be derived using low-cost and low-tech techniques. Further analysis using these same techniques is required in order to link relatively small scale vegetation dynamics measured with KAP with those documented at large scales using satellite imagery.

Eliminating Survivor Bias in Two-stage Instrumental Variable Estimators.

PubMed

Vansteelandt, Stijn; Walter, Stefan; Tchetgen Tchetgen, Eric

2018-07-01

Mendelian randomization studies commonly focus on elderly populations. This makes the instrumental variables analysis of such studies sensitive to survivor bias, a type of selection bias. A particular concern is that the instrumental variable conditions, even when valid for the source population, may be violated for the selective population of individuals who survive the onset of the study. This is potentially very damaging because Mendelian randomization studies are known to be sensitive to bias due to even minor violations of the instrumental variable conditions. Interestingly, the instrumental variable conditions continue to hold within certain risk sets of individuals who are still alive at a given age when the instrument and unmeasured confounders exert additive effects on the exposure, and moreover, the exposure and unmeasured confounders exert additive effects on the hazard of death. In this article, we will exploit this property to derive a two-stage instrumental variable estimator for the effect of exposure on mortality, which is insulated against the above described selection bias under these additivity assumptions.

76 FR 20948 - Sensors and Instrumentation Technical Advisory Committee; Notice of Partially Closed Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-14

... DEPARTMENT OF COMMERCE Bureau of Industry and Security Sensors and Instrumentation Technical Advisory Committee; Notice of Partially Closed Meeting The Sensors and Instrumentation Technical Advisory... of export controls applicable to sensors [[Page 20949

Instrument and Survey Analysis Technical Report: Program Implementation Survey. Technical Report #1112

ERIC Educational Resources Information Center

Alonzo, Julie; Tindal, Gerald

2011-01-01

This technical document provides guidance to educators on the creation and interpretation of survey instruments, particularly as they relate to an analysis of program implementation. Illustrative examples are drawn from a survey of educators related to the use of the easyCBM learning system. This document includes specific sections on…

Instrumental variables and Mendelian randomization with invalid instruments

NASA Astrophysics Data System (ADS)

Kang, Hyunseung

Instrumental variables (IV) methods have been widely used to determine the causal effect of a treatment, exposure, policy, or an intervention on an outcome of interest. The IV method relies on having a valid instrument, a variable that is (A1) associated with the exposure, (A2) has no direct effect on the outcome, and (A3) is unrelated to the unmeasured confounders associated with the exposure and the outcome. However, in practice, finding a valid instrument, especially those that satisfy (A2) and (A3), can be challenging. For example, in Mendelian randomization studies where genetic markers are used as instruments, complete knowledge about instruments' validity is equivalent to complete knowledge about the involved genes' functions. The dissertation explores the theory, methods, and application of IV methods when invalid instruments are present. First, when we have multiple candidate instruments, we establish a theoretical bound whereby causal effects are only identified as long as less than 50% of instruments are invalid, without knowing which of the instruments are invalid. We also propose a fast penalized method, called sisVIVE, to estimate the causal effect. We find that sisVIVE outperforms traditional IV methods when invalid instruments are present both in simulation studies as well as in real data analysis. Second, we propose a robust confidence interval under the multiple invalid IV setting. This work is an extension of our work on sisVIVE. However, unlike sisVIVE which is robust to violations of (A2) and (A3), our confidence interval procedure provides honest coverage even if all three assumptions, (A1)-(A3), are violated. Third, we study the single IV setting where the one IV we have may actually be invalid. We propose a nonparametric IV estimation method based on full matching, a technique popular in causal inference for observational data, that leverages observed covariates to make the instrument more valid. We propose an estimator along with

Soot Particle Studies - Instrument Inter-Comparison – Project Overview

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

Cross, E.; Sedlacek, A.; Onasch, T. B.

2010-03-06

An inter-comparison study of instruments designed to measure the microphysical and optical properties of soot particles was completed. The following mass-based instruments were tested: Couette Centrifugal Particle Mass Analyzer (CPMA), Time-of-Flight Aerosol Mass Spectrometer - Scanning Mobility Particle Sizer (AMS-SMPS), Single Particle Soot Photometer (SP2), Soot Particle-Aerosol Mass Spectrometer (SP-AMS) and Photoelectric Aerosol Sensor (PAS2000CE). Optical instruments measured absorption (photoacoustic, interferometric, and filter-based), scattering (in situ), and extinction (light attenuation within an optical cavity). The study covered an experimental matrix consisting of 318 runs that systematically tested the performance of instruments across a range of parameters including: fuel equivalence ratiomore » (1.8 {le} {phi} {le} 5), particle shape (mass-mobility exponent (D{sub f m}), 2.0 {le} D{sub f m} {le} 3.0), particle mobility size (30 {le} d{sub m} {le} 300 nm), black carbon mass (0.07 {le} m{sub BC} {le} 4.2 fg) and particle chemical composition. In selected runs, particles were coated with sulfuric acid or dioctyl sebacate (DOS) (0.5 {le} {Delta}r{sub ve} {le} 201 nm) where {Delta}r{sub ve} is the change in the volume equivalent radius due to the coating material. The effect of non-absorbing coatings on instrument response was determined. Changes in the morphology of fractal soot particles were monitored during coating and denuding processes and the effect of particle shape on instrument response was determined. The combination of optical and mass based measurements was used to determine the mass specific absorption coefficient for denuded soot particles. The single scattering albedo of the particles was also measured. An overview of the experiments and sample results are presented.« less

Compliance-Effect Correlation Bias in Instrumental Variables Estimators

ERIC Educational Resources Information Center

Reardon, Sean F.

2010-01-01

Instrumental variable estimators hold the promise of enabling researchers to estimate the effects of educational treatments that are not (or cannot be) randomly assigned but that may be affected by randomly assigned interventions. Examples of the use of instrumental variables in such cases are increasingly common in educational and social science…

Falsification Testing of Instrumental Variables Methods for Comparative Effectiveness Research.

PubMed

Pizer, Steven D

2016-04-01

To demonstrate how falsification tests can be used to evaluate instrumental variables methods applicable to a wide variety of comparative effectiveness research questions. Brief conceptual review of instrumental variables and falsification testing principles and techniques accompanied by an empirical application. Sample STATA code related to the empirical application is provided in the Appendix. Comparative long-term risks of sulfonylureas and thiazolidinediones for management of type 2 diabetes. Outcomes include mortality and hospitalization for an ambulatory care-sensitive condition. Prescribing pattern variations are used as instrumental variables. Falsification testing is an easily computed and powerful way to evaluate the validity of the key assumption underlying instrumental variables analysis. If falsification tests are used, instrumental variables techniques can help answer a multitude of important clinical questions. © Health Research and Educational Trust.

Genetic markers as instrumental variables.

PubMed

von Hinke, Stephanie; Davey Smith, George; Lawlor, Debbie A; Propper, Carol; Windmeijer, Frank

2016-01-01

The use of genetic markers as instrumental variables (IV) is receiving increasing attention from economists, statisticians, epidemiologists and social scientists. Although IV is commonly used in economics, the appropriate conditions for the use of genetic variants as instruments have not been well defined. The increasing availability of biomedical data, however, makes understanding of these conditions crucial to the successful use of genotypes as instruments. We combine the econometric IV literature with that from genetic epidemiology, and discuss the biological conditions and IV assumptions within the statistical potential outcomes framework. We review this in the context of two illustrative applications. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Inter-annual Variability of Snowfall in the Lower Peninsula of Michigan, USA

NASA Astrophysics Data System (ADS)

Meng, L.

2016-12-01

Winter snowfall, particularly lake-effect snowfall, impacts all aspects of Michigan life in the wintertime, from motorsports and tourism to impacting the day-to-day lives of residents. Understanding the inter-annual variability of winter snowfall will provide sound basis for local community safety management and improve weather forecasting. This study attempts to understand the trend in winter snowfall and the influencing factors of winter snowfall variability in the Lower Peninsula of Michigan (LPM) using station snowfall measurements and statistical analysis. Our study demonstrates that snowfall has significantly increased from 1932 to 2015. Correlation analysis suggests that regionally average air temperatures have a strong negative relationship with snowfall in LPM. On average, approximately 27% of inter-annual variability in snowfall can be explained by regionally average air temperatures. ENSO events are also negatively related to snowfall in LPM and can explain 8% of inter-annual variability. North Atlantic Oscillation (NAO) does not have strong influence on snowfall. Composite analysis demonstrates that on annual basis, more winter snowfall occurs during the years with higher maximum ice cover (MIC) than during the years with lower MIC in Lake Michigan. Higher MIC is often associated with lower air temperatures which are negatively related to winter snowfall. This study could provide insight on future snow related climate model improvement and weather forecasting.

Inter-individual Variability in Soccer Players of Different Age Groups Playing Different Positions

PubMed Central

Nikolaidis, Pantelis; Ziv, Gal; Lidor, Ronnie; Arnon, Michal

2014-01-01

The purpose of this study was twofold: (a) to profile physical characteristics and motor abilities of three age groups of soccer players – under 14 years, 14–17, and over 17, playing different positions – goalkeepers, defenders, midfielders, and forwards; and (b) to examine the inter-individual variability among the players in each age group in all physical and physiological measurements performed in the study. In addition, anthropometric, power, strength, and flexibility tests were administered. Findings showed large inter-individual variability in all three age groups and in all playing positions. Differences between playing positions were found only in the 14–17 group (body mass) and in the over-17 group (body height, body mass, fat-free mass, and mean power in the Wingate Anaerobic Test). Due to the observed large inter-individual variability, it was concluded that the findings obtained in the physical and physiological tests should be interpreted with caution when attempting to differentiate between successful and unsuccessful soccer players, as well as when trying to predict future success in soccer. PMID:25031689

3D facial landmarks: Inter-operator variability of manual annotation

PubMed Central

2014-01-01

Background Manual annotation of landmarks is a known source of variance, which exist in all fields of medical imaging, influencing the accuracy and interpretation of the results. However, the variability of human facial landmarks is only sparsely addressed in the current literature as opposed to e.g. the research fields of orthodontics and cephalometrics. We present a full facial 3D annotation procedure and a sparse set of manually annotated landmarks, in effort to reduce operator time and minimize the variance. Method Facial scans from 36 voluntary unrelated blood donors from the Danish Blood Donor Study was randomly chosen. Six operators twice manually annotated 73 anatomical and pseudo-landmarks, using a three-step scheme producing a dense point correspondence map. We analyzed both the intra- and inter-operator variability, using mixed-model ANOVA. We then compared four sparse sets of landmarks in order to construct a dense correspondence map of the 3D scans with a minimum point variance. Results The anatomical landmarks of the eye were associated with the lowest variance, particularly the center of the pupils. Whereas points of the jaw and eyebrows have the highest variation. We see marginal variability in regards to intra-operator and portraits. Using a sparse set of landmarks (n=14), that capture the whole face, the dense point mean variance was reduced from 1.92 to 0.54 mm. Conclusion The inter-operator variability was primarily associated with particular landmarks, where more leniently landmarks had the highest variability. The variables embedded in the portray and the reliability of a trained operator did only have marginal influence on the variability. Further, using 14 of the annotated landmarks we were able to reduced the variability and create a dense correspondences mesh to capture all facial features. PMID:25306436

Toward a clearer portrayal of confounding bias in instrumental variable applications.

PubMed

Jackson, John W; Swanson, Sonja A

2015-07-01

Recommendations for reporting instrumental variable analyses often include presenting the balance of covariates across levels of the proposed instrument and levels of the treatment. However, such presentation can be misleading as relatively small imbalances among covariates across levels of the instrument can result in greater bias because of bias amplification. We introduce bias plots and bias component plots as alternative tools for understanding biases in instrumental variable analyses. Using previously published data on proposed preference-based, geography-based, and distance-based instruments, we demonstrate why presenting covariate balance alone can be problematic, and how bias component plots can provide more accurate context for bias from omitting a covariate from an instrumental variable versus non-instrumental variable analysis. These plots can also provide relevant comparisons of different proposed instruments considered in the same data. Adaptable code is provided for creating the plots.

Instrumental Variable Analysis with a Nonlinear Exposure–Outcome Relationship

PubMed Central

Davies, Neil M.; Thompson, Simon G.

2014-01-01

Background: Instrumental variable methods can estimate the causal effect of an exposure on an outcome using observational data. Many instrumental variable methods assume that the exposure–outcome relation is linear, but in practice this assumption is often in doubt, or perhaps the shape of the relation is a target for investigation. We investigate this issue in the context of Mendelian randomization, the use of genetic variants as instrumental variables. Methods: Using simulations, we demonstrate the performance of a simple linear instrumental variable method when the true shape of the exposure–outcome relation is not linear. We also present a novel method for estimating the effect of the exposure on the outcome within strata of the exposure distribution. This enables the estimation of localized average causal effects within quantile groups of the exposure or as a continuous function of the exposure using a sliding window approach. Results: Our simulations suggest that linear instrumental variable estimates approximate a population-averaged causal effect. This is the average difference in the outcome if the exposure for every individual in the population is increased by a fixed amount. Estimates of localized average causal effects reveal the shape of the exposure–outcome relation for a variety of models. These methods are used to investigate the relations between body mass index and a range of cardiovascular risk factors. Conclusions: Nonlinear exposure–outcome relations should not be a barrier to instrumental variable analyses. When the exposure–outcome relation is not linear, either a population-averaged causal effect or the shape of the exposure–outcome relation can be estimated. PMID:25166881

Inter-individual variability in response to non-invasive brain stimulation paradigms.

PubMed

López-Alonso, Virginia; Cheeran, Binith; Río-Rodríguez, Dan; Fernández-Del-Olmo, Miguel

2014-01-01

Non-invasive Brain Stimulation (NIBS) paradigms are unique in their ability to safely modulate cortical plasticity for experimental or therapeutic applications. However, increasingly, there is concern regarding inter-individual variability in the efficacy and reliability of these paradigms. Inter-individual variability in response to NIBS paradigms would be better explained if a multimodal distribution was assumed. In three different sessions for each subject (n = 56), we studied the Paired Associative Stimulation (PAS25), Anodal transcranial DC stimulation (AtDCS) and intermittent theta burst stimulation (iTBS) protocols. We applied cluster analysis to detect distinct patterns of response between individuals. Furthermore, we tested whether baseline TMS measures (such as short intracortical inhibition (SICI), resting motor threshold (RMT)) or factors such as time of day could predict each individual's response pattern. All three paradigms show similar efficacy over the first hour post stimulation--there is no significant effect on excitatory or inhibitory circuits for the whole sample, and AtDCS fares no better than iTBS or PAS25. Cluster analysis reveals a bimodal response pattern--but only 39%, 45% and 43% of subjects responded as expected to PAS25, AtDCS, and iTBS respectively. Pre-stimulation SICI accounted for 10% of the variability in response to PAS25, but no other baseline measures were predictive of response. Finally, we report implications for sample size calculation and the remarkable effect of sample enrichment. The implications of the high rate of 'dose-failure' for experimental and therapeutic applications of NIBS lead us to conclude that addressing inter-individual variability is a key area of concern for the field. Copyright © 2014 Elsevier Inc. All rights reserved.

Inter-individual variability and pattern recognition of surface electromyography in front crawl swimming.

PubMed

Martens, Jonas; Daly, Daniel; Deschamps, Kevin; Staes, Filip; Fernandes, Ricardo J

2016-12-01

Variability of electromyographic (EMG) recordings is a complex phenomenon rarely examined in swimming. Our purposes were to investigate inter-individual variability in muscle activation patterns during front crawl swimming and assess if there were clusters of sub patterns present. Bilateral muscle activity of rectus abdominis (RA) and deltoideus medialis (DM) was recorded using wireless surface EMG in 15 adult male competitive swimmers. The amplitude of the median EMG trial of six upper arm movement cycles was used for the inter-individual variability assessment, quantified with the coefficient of variation, coefficient of quartile variation, the variance ratio and mean deviation. Key features were selected based on qualitative and quantitative classification strategies to enter in a k-means cluster analysis to examine the presence of strong sub patterns. Such strong sub patterns were found when clustering in two, three and four clusters. Inter-individual variability in a group of highly skilled swimmers was higher compared to other cyclic movements which is in contrast to what has been reported in the previous 50years of EMG research in swimming. This leads to the conclusion that coaches should be careful in using overall reference EMG information to enhance the individual swimming technique of their athletes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Characterization of inter-tissue and inter-strain variability of TCE glutathione conjugation metabolites DCVG, DCVC, and NAcDCVC in the mouse.

PubMed

Luo, Yu-Syuan; Furuya, Shinji; Chiu, Weihsueh; Rusyn, Ivan

2018-01-01

Trichloroethylene (TCE) is a ubiquitous environmental toxicant that is a liver and kidney carcinogen. Conjugation of TCE with glutathione (GSH) leads to formation of nepthrotoxic and mutagenic metabolites postulated to be critical for kidney cancerdevelopment; however, relatively little is known regarding their tissue levels as previous analytical methods for their detection lacked sensitivity. Here, an LC-MS/MS-based method for simultaneous detection of S-(1,2-dichlorovinyl)-glutathione (DCVG), S-(1,2-dichlorovinyl)-L-cysteine (DCVC), and N-acetyl-S-(1,2-dichlorovinyl)-L-cysteine (NAcDCVC) in multiple mouse tissues was developed. This analytical method is rapid, sensitive (limits of detection (LOD) 3-30 fmol across metabolites and tissues), and robust to quantify all three metabolites in liver, kidneys, and serum. The method was used to characterize inter-tissue and inter-strain variability in formation of conjugative metabolites of TCE. Single oral dose of TCE (24, 240 or 800 mg/kg) was administered to male mice from 20 inbred strains of Collaborative Cross. Inter-strain variability in the levels of DCVG, DCVC, and NAcDCVC (GSD = 1.6-2.9) was observed. Whereas NAcDCVC was distributed equally among analyzed tissues, highest levels of DCVG were detected in liver and DCVC in kidneys. Evidence indicated that inter-strain variability in conjugative metabolite formation of TCE might affect susceptibility to adverse health effects and that this method might aid in filling data gaps in human health assessment of TCE.

Evaluation of inter-day and inter-individual variability of tear peptide/protein profiles by MALDI-TOF MS analyses

PubMed Central

González, Nerea; Iloro, Ibon; Durán, Juan A.; Elortza, Félix

2012-01-01

Purpose To characterize the tear film peptidome and low molecular weight protein profiles of healthy control individuals, and to evaluate changes due to day-to-day and individual variation and tear collection methods, by using solid phase extraction coupled to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiling. Methods The tear protein profiles of six healthy volunteers were analyzed over seven days and inter-day and inter-individual variability was evaluated. The bilaterality of tear film and the effect of tear collection methods on protein profiles were also analyzed in some of these patients. MALDI-TOF MS analyses were performed on tear samples purified by using a solid phase extraction (SPE) method based on C18 functionalized magnetic beads for peptide and low molecular weight protein enrichment, focusing spectra acquisition on the 1 to 20 kDa range. Spectra were analyzed using principal component analysis (PCA) with MultiExperiment Viewer (TMeV) software. Volunteers were examined in terms of tear production status (Schirmer I test), clinical assessment of palpebral lids and meibomian glands, and a subjective OSD questionnaire before tear collection by a glass micro-capillary. Results Analysis of peptides and proteins in the 1–20 kDa range showed no significant inter-day differences in tear samples collected from six healthy individuals during seven days of monitoring, but revealed subtle intrinsic inter-individual differences. Profile analyses of tears collected from the right and left eyes confirmed tear bilaterality in four healthy patients. The addition of physiologic serum for tear sample collection did not affect the peptide and small protein profiles with respect to the number of resolved peaks, but it did reduce the signal intensity of the peaks, and increased variability. Magnetic beads were found to be a suitable method for tear film purification for the profiling study. Conclusions No significant

Watershed-scale response of groundwater recharge to inter-annual and inter-decadal variability in precipitation (Alberta, Canada)

NASA Astrophysics Data System (ADS)

Hayashi, Masaki; Farrow, Christopher R.

2014-12-01

Groundwater recharge sets a constraint on aquifer water balance in the context of water management. Historical data on groundwater and other relevant hydrological processes can be used to understand the effects of climatic variability on recharge, but such data sets are rare. The climate of the Canadian prairies is characterized by large inter-annual and inter-decadal variability in precipitation, which provides opportunities to examine the response of groundwater recharge to changes in meteorological conditions. A decadal study was conducted in a small (250 km2) prairie watershed in Alberta, Canada. Relative magnitude of annual recharge, indicated by water-level rise, was significantly correlated with a combination of growing-season precipitation and snowmelt runoff, which drives depression-focussed infiltration of meltwater. Annual precipitation was greater than vapour flux at an experimental site in some years and smaller in other years. On average precipitation minus vapour flux was 10 mm y-1, which was comparable to the magnitude of watershed-scale groundwater recharge estimated from creek baseflow. Average baseflow showed a distinct shift from a low value (4 mm y-1) in 1982-1995 to a high value (15 mm y-1) in 2003-2013, indicating the sensitivity of groundwater recharge to a decadal-scale variability of meteorological conditions.

Statistically Characterizing Intra- and Inter-Individual Variability in Children with Developmental Coordination Disorder

ERIC Educational Resources Information Center

King, Bradley R.; Harring, Jeffrey R.; Oliveira, Marcio A.; Clark, Jane E.

2011-01-01

Previous research investigating children with Developmental Coordination Disorder (DCD) has consistently reported increased intra- and inter-individual variability during motor skill performance. Statistically characterizing this variability is not only critical for the analysis and interpretation of behavioral data, but also may facilitate our…

Instrumental variables I: instrumental variables exploit natural variation in nonexperimental data to estimate causal relationships.

PubMed

Rassen, Jeremy A; Brookhart, M Alan; Glynn, Robert J; Mittleman, Murray A; Schneeweiss, Sebastian

2009-12-01

The gold standard of study design for treatment evaluation is widely acknowledged to be the randomized controlled trial (RCT). Trials allow for the estimation of causal effect by randomly assigning participants either to an intervention or comparison group; through the assumption of "exchangeability" between groups, comparing the outcomes will yield an estimate of causal effect. In the many cases where RCTs are impractical or unethical, instrumental variable (IV) analysis offers a nonexperimental alternative based on many of the same principles. IV analysis relies on finding a naturally varying phenomenon, related to treatment but not to outcome except through the effect of treatment itself, and then using this phenomenon as a proxy for the confounded treatment variable. This article demonstrates how IV analysis arises from an analogous but potentially impossible RCT design, and outlines the assumptions necessary for valid estimation. It gives examples of instruments used in clinical epidemiology and concludes with an outline on estimation of effects.

Instrumental variables I: instrumental variables exploit natural variation in nonexperimental data to estimate causal relationships

PubMed Central

Rassen, Jeremy A.; Brookhart, M. Alan; Glynn, Robert J.; Mittleman, Murray A.; Schneeweiss, Sebastian

2010-01-01

The gold standard of study design for treatment evaluation is widely acknowledged to be the randomized controlled trial (RCT). Trials allow for the estimation of causal effect by randomly assigning participants either to an intervention or comparison group; through the assumption of “exchangeability” between groups, comparing the outcomes will yield an estimate of causal effect. In the many cases where RCTs are impractical or unethical, instrumental variable (IV) analysis offers a nonexperimental alternative based on many of the same principles. IV analysis relies on finding a naturally varying phenomenon, related to treatment but not to outcome except through the effect of treatment itself, and then using this phenomenon as a proxy for the confounded treatment variable. This article demonstrates how IV analysis arises from an analogous but potentially impossible RCT design, and outlines the assumptions necessary for valid estimation. It gives examples of instruments used in clinical epidemiology and concludes with an outline on estimation of effects. PMID:19356901

Mn/Ca intra- and inter-test variability in the benthic foraminifer Ammonia tepida

NASA Astrophysics Data System (ADS)

Petersen, Jassin; Barras, Christine; Bézos, Antoine; La, Carole; de Nooijer, Lennart J.; Meysman, Filip J. R.; Mouret, Aurélia; Slomp, Caroline P.; Jorissen, Frans J.

2018-01-01

The adaptation of some benthic foraminiferal species to low-oxygen conditions provides the prospect of using the chemical composition of their tests as proxies for bottom water oxygenation. Manganese may be particularly suitable as such a geochemical proxy because this redox element is soluble in reduced form (Mn2+) and hence can be incorporated into benthic foraminiferal tests under low-oxygen conditions. Therefore, intra- and inter-test differences in foraminiferal Mn/Ca ratios may hold important information about short-term variability in pore water Mn2+ concentrations and sediment redox conditions. Here, we studied Mn/Ca intra- and inter-test variability in living individuals of the shallow infaunal foraminifer Ammonia tepida sampled in Lake Grevelingen (the Netherlands) in three different months of 2012. The deeper parts of this lake are characterized by seasonal hypoxia/anoxia with associated shifts in microbial activity and sediment geochemistry, leading to seasonal Mn2+ accumulation in the pore water. Earlier laboratory experiments with similar seawater Mn2+ concentrations as encountered in the pore waters of Lake Grevelingen suggest that intra-test variability due to ontogenetic trends (i.e. size-related effects) and/or other vital effects occurring during calcification in A. tepida (11-25 % relative SD, RSD) is responsible for part of the observed variability in Mn/Ca. Our present results show that the seasonally highly dynamic environmental conditions in the study area lead to a strongly increased Mn/Ca intra- and inter-test variability (average of 45 % RSD). Within single specimens, both increasing and decreasing trends in Mn/Ca ratios with size are observed. Our results suggest that the variability in successive single-chamber Mn/Ca ratios reflects the temporal variability in pore water Mn2+. Additionally, active or passive migration of the foraminifera in the surface sediment may explain part of the observed Mn/Ca variability.

Analytic assessment of Laplacian estimates via novel variable interring distances concentric ring electrodes.

PubMed

Makeyev, Oleksandr; Besio, Walter G

2016-08-01

Noninvasive concentric ring electrodes are a promising alternative to conventional disc electrodes. Currently, superiority of tripolar concentric ring electrodes over disc electrodes, in particular, in accuracy of Laplacian estimation has been demonstrated in a range of applications. In our recent work we have shown that accuracy of Laplacian estimation can be improved with multipolar concentric ring electrodes using a general approach to estimation of the Laplacian for an (n + 1)-polar electrode with n rings using the (4n + 1)-point method for n ≥ 2. This paper takes the next step toward further improving the Laplacian estimate by proposing novel variable inter-ring distances concentric ring electrodes. Derived using a modified (4n + 1)-point method, linearly increasing inter-ring distances tripolar (n = 2) and quadripolar (n = 3) electrode configurations are analytically compared to their constant inter-ring distances counterparts using coefficients of the Taylor series truncation terms. Obtained results suggest that increasing inter-ring distances electrode configurations may decrease the truncation error of the Laplacian estimation resulting in more accurate Laplacian estimates compared to respective constant inter-ring distances configurations. For currently used tripolar electrode configuration the truncation error may be decreased more than two-fold while for the quadripolar more than seven-fold decrease is expected.

A Polychoric Instrumental Variable (PIV) Estimator for Structural Equation Models with Categorical Variables

ERIC Educational Resources Information Center

Bollen, Kenneth A.; Maydeu-Olivares, Albert

2007-01-01

This paper presents a new polychoric instrumental variable (PIV) estimator to use in structural equation models (SEMs) with categorical observed variables. The PIV estimator is a generalization of Bollen's (Psychometrika 61:109-121, 1996) 2SLS/IV estimator for continuous variables to categorical endogenous variables. We derive the PIV estimator…

Facility Instrumentation for SOFIA: Technical Specifications and Scientific Goals

NASA Astrophysics Data System (ADS)

Stacey, G. J.

2000-05-01

The Stratospheric Observatory for Infrared Astronomy (SOFIA) is NASA's next generation airborne observatory consisting of a 2.5 m telescope in a modified Boeing 747 SP. First light is expected in late 2002. Three "Facility Class" instruments were among the first generation of instruments selected to fly on SOFIA. These instruments, currently under development are (1) a 5 to 38 um imaging photometer based on twin As:Si and Sb:Sb BIB arrays (FORCAST), (2) a 40 to 300 um photometer based on three arrays of bolometers, and (3) a 17 to 210 um eschelle grating spectrometer based on an Sb:Sb BIB array and a Ge:Sb and stressed Ge:Ga array of photoconductors. I will discuss both the technical aspects of these facility instruments, and some of the exciting new science that is possible with these ground breaking instruments on an airborne 2.5 meter telescope. Science topics include circumstellar debris disks, star formation, the Galactic Center, and distant galaxies.

High inter-specimen variability of baseline data for the tibio-talar contact area.

PubMed

Matricali, Giovanni A; Bartels, Ward; Labey, Luc; Dereymaeker, Greta Ph E; Luyten, Frank P; Vander Sloten, Jos

2009-01-01

The tibio-talar contact area has been widely investigated to monitor biomechanical changes due to articular incongruities or an altered loading. This study aims to investigate for the first time in a systematic way the extent of the inter-specimen variability of the tibio-talar contact area, and its repercussions when analyzing data concerning this parameter. Ten specimens were loaded to record the tibio-talar contact characteristics by use of pressure sensitive film. The size of the talar dome area, the size of the (normalized) tibio-talar contact area, the position of the tibio-talar contact area, and the shape of the latter were determined and analyzed. Inter-specimen variability was expressed as the coefficient of variation and was calculated for the datasets of previous studies as well. The size of the tibio-talar contact area showed a very high inter-specimen variability, as is the case in previous studies. This high variability persisted when a normalized tibio-talar contact area was calculated. The shape of the tibio-talar contact area showed some basic characteristics, but a high variation in details could be observed. Every specimen can be considered to have its own "ankle print". By this variability, articular incongruities are expected to have a different effect on local biomechanical characteristics in every single individual. Therefore, every single case has to be evaluated and reported for significant changes. In case of modeling, this also underscores the need to use subject specific models fed by sets of parameters derived from a series of single specimens.

78 FR 63161 - Sensors and Instrumentation Technical Advisory Committee; Notice of Partially Closed Meeting...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-23

... DEPARTMENT OF COMMERCE Bureau of Industry and Security Sensors and Instrumentation Technical Advisory Committee; Notice of Partially Closed Meeting ``Rescheduled'' The Sensors and Instrumentation... that affect the level of export controls applicable to sensors and instrumentation equipment and...

Implementation of Instrumental Variable Bounds for Data Missing Not at Random.

PubMed

Marden, Jessica R; Wang, Linbo; Tchetgen, Eric J Tchetgen; Walter, Stefan; Glymour, M Maria; Wirth, Kathleen E

2018-05-01

Instrumental variables are routinely used to recover a consistent estimator of an exposure causal effect in the presence of unmeasured confounding. Instrumental variable approaches to account for nonignorable missing data also exist but are less familiar to epidemiologists. Like instrumental variables for exposure causal effects, instrumental variables for missing data rely on exclusion restriction and instrumental variable relevance assumptions. Yet these two conditions alone are insufficient for point identification. For estimation, researchers have invoked a third assumption, typically involving fairly restrictive parametric constraints. Inferences can be sensitive to these parametric assumptions, which are typically not empirically testable. The purpose of our article is to discuss another approach for leveraging a valid instrumental variable. Although the approach is insufficient for nonparametric identification, it can nonetheless provide informative inferences about the presence, direction, and magnitude of selection bias, without invoking a third untestable parametric assumption. An important contribution of this article is an Excel spreadsheet tool that can be used to obtain empirical evidence of selection bias and calculate bounds and corresponding Bayesian 95% credible intervals for a nonidentifiable population proportion. For illustrative purposes, we used the spreadsheet tool to analyze HIV prevalence data collected by the 2007 Zambia Demographic and Health Survey (DHS).

Inter-individual variability in high-throughput risk prioritization of environmental chemicals (IVIVE)

EPA Science Inventory

We incorporate inter-individual variability into an open-source high-throughput (HT) toxicokinetics (TK) modeling framework for use in a next-generation risk prioritization approach. Risk prioritization involves rapid triage of thousands of environmental chemicals, most which hav...

Inter-observer variability in fetal biometric measurements.

PubMed

Kilani, Rami; Aleyadeh, Wesam; Atieleh, Luay Abu; Al Suleimat, Abdul Mane; Khadra, Maysa; Hawamdeh, Hassan M

2018-02-01

To evaluate inter-observer variability and reproducibility of ultrasound measurements for fetal biometric parameters. A prospective cohort study was implemented in two tertiary care hospitals in Amman, Jordan; Prince Hamza Hospital and Albashir Hospital. 192 women with a singleton pregnancy at a gestational age of 18-36 weeks were the participants in the study. Transabdominal scans for fetal biometric parameter measurement were performed on study participants from the period of November 2014 to March 2015. Women who agreed to participate in the study were administered two ultrasound scans for head circumference, abdominal circumference and femur length. The correlation coefficient was calculated. Bland-Altman plots were used to analyze the degree of measurement agreement between observers. Limits of agreement ± 2 SD for the differences in fetal biometry measurements in proportions of the mean of the measurements were derived. Main outcome measures examine the reproducibility of fetal biometric measurements by different observers. High inter-observer inter-class correlation coefficient (ICC) was found for femur length (0.990) and abdominal circumference (0.996) where Bland-Altman plots showed high degrees of agreement. The highest degrees of agreement were noted in the measurement of abdominal circumference followed by head circumference. The lowest degree of agreement was found for femur length measurement. We used a paired-sample t-test and found that the mean difference between duplicate measurements was not significant (P > 0.05). Biometric fetal parameter measurements may be reproducible by different operators in the clinical setting with similar results. Fetal head circumference, abdominal circumference and femur length were highly reproducible. Large organized studies are needed to ensure accurate fetal measurements due to the important clinical implications of inaccurate measurements. Copyright © 2018. Published by Elsevier B.V.

An instrumental variable random-coefficients model for binary outcomes

PubMed Central

Chesher, Andrew; Rosen, Adam M

2014-01-01

In this paper, we study a random-coefficients model for a binary outcome. We allow for the possibility that some or even all of the explanatory variables are arbitrarily correlated with the random coefficients, thus permitting endogeneity. We assume the existence of observed instrumental variables Z that are jointly independent with the random coefficients, although we place no structure on the joint determination of the endogenous variable X and instruments Z, as would be required for a control function approach. The model fits within the spectrum of generalized instrumental variable models, and we thus apply identification results from our previous studies of such models to the present context, demonstrating their use. Specifically, we characterize the identified set for the distribution of random coefficients in the binary response model with endogeneity via a collection of conditional moment inequalities, and we investigate the structure of these sets by way of numerical illustration. PMID:25798048

The impact of inter-annual rainfall variability on African savannas changes with mean rainfall.

PubMed

Synodinos, Alexis D; Tietjen, Britta; Lohmann, Dirk; Jeltsch, Florian

2018-01-21

Savannas are mixed tree-grass ecosystems whose dynamics are predominantly regulated by resource competition and the temporal variability in climatic and environmental factors such as rainfall and fire. Hence, increasing inter-annual rainfall variability due to climate change could have a significant impact on savannas. To investigate this, we used an ecohydrological model of stochastic differential equations and simulated African savanna dynamics along a gradient of mean annual rainfall (520-780 mm/year) for a range of inter-annual rainfall variabilities. Our simulations produced alternative states of grassland and savanna across the mean rainfall gradient. Increasing inter-annual variability had a negative effect on the savanna state under dry conditions (520 mm/year), and a positive effect under moister conditions (580-780 mm/year). The former resulted from the net negative effect of dry and wet extremes on trees. In semi-arid conditions (520 mm/year), dry extremes caused a loss of tree cover, which could not be recovered during wet extremes because of strong resource competition and the increased frequency of fires. At high mean rainfall (780 mm/year), increased variability enhanced savanna resilience. Here, resources were no longer limiting and the slow tree dynamics buffered against variability by maintaining a stable population during 'dry' extremes, providing the basis for growth during wet extremes. Simultaneously, high rainfall years had a weak marginal benefit on grass cover due to density-regulation and grazing. Our results suggest that the effects of the slow tree and fast grass dynamics on tree-grass interactions will become a major determinant of the savanna vegetation composition with increasing rainfall variability. Copyright © 2017 Elsevier Ltd. All rights reserved.

Inter-annual variability of North Sea plaice spawning habitat

NASA Astrophysics Data System (ADS)

Loots, C.; Vaz, S.; Koubbi, P.; Planque, B.; Coppin, F.; Verin, Y.

2010-11-01

Potential spawning habitat is defined as the area where environmental conditions are suitable for spawning to occur. Spawning adult data from the first quarter (January-March) of the International Bottom Trawl Survey have been used to study the inter-annual variability of the potential spawning habitat of North Sea plaice from 1980 to 2007. Generalised additive models (GAM) were used to create a model that related five environmental variables (depth, bottom temperature and salinity, seabed stress and sediment type) to presence-absence and abundance of spawning adults. Then, the habitat model was applied each year from 1970 to 2007 to predict inter-annual variability of the potential spawning habitat. Predicted responses obtained by GAM for each year were mapped using kriging. A hierarchical classification associated with a correspondence analysis was performed to cluster spawning suitable areas and to determine how they evolved across years. The potential spawning habitat was consistent with historical spawning ground locations described in the literature from eggs surveys. It was also found that the potential spawning habitat varied across years. Suitable areas were located in the southern part of the North Sea and along the eastern coast of England and Scotland in the eighties; they expanded further north from the nineties. Annual survey distributions did not show such northward expansion and remained located in the southern North Sea. This suggests that this species' actual spatial distribution remains stable against changing environmental conditions, and that the potential spawning habitat is not fully occupied. Changes in environmental conditions appear to remain within plaice environmental ranges, meaning that other factors may control the spatial distribution of plaice spawning habitat.

Factors influencing physical and technical variability in the English Premier League.

PubMed

Bush, Michael D; Archer, David T; Hogg, Robert; Bradley, Paul S

2015-10-01

To investigate match-to-match variability of physical and technical performances in English Premier League players and quantify the influence of positional and contextual factors. Match data (N = 451) were collected using a multicamera computerized tracking system across multiple seasons (2005-06 to 2012-13). The coefficient of variation (CV) was calculated from match to match for physical and technical performances in selected positions across different match contexts (location, standard, and result). Wide midfielders demonstrated the greatest CVs for total distance (4.9% ± 5.9%) and central midfielders the smallest (3.6% ± 2.0%); nevertheless, all positions exhibited CVs <5% (P > .05, effect size [ES] 0.1-0.3). Central defenders demonstrated the greatest CVs and wide midfielders the lowest for both high-intensity running (20.2% ± 8.8% and 13.7% ± 7.7%, P < .05, ES 0.4-0.8) and sprint distance (32.3% ± 13.8% and 22.6% ± 11.2%, P < .05, ES 0.5-0.8). Technical indicators such as tackles (83.7% ± 42.3%), possessions won (47.2% ± 27.9%), and interceptions (59.1% ± 37.3%) illustrated substantial variability for attackers compared with all other positions (P < .05, ES 0.4-1.1). Central defenders demonstrated large variability for the number of times tackled per match (144.9% ± 58.3%) and passes attempted and received compared with other positions (39.2% ± 17.5% and 46.9% ± 20.2%, P < .001, ES 0.6-1.8). Contextual factors had limited impact on the variability of physical and technical parameters. The data demonstrate that technical parameters varied more from match to match than physical parameters. Defensive players (fullbacks and central defenders) displayed higher CVs for offensive technical variables, while attacking players (attackers and wide midfielders) exhibited higher CVs for defensive technical variables. Physical and technical performances are variable per se regardless of context.

Histone H4 acetylation regulates behavioral inter-individual variability in zebrafish.

PubMed

Román, Angel-Carlos; Vicente-Page, Julián; Pérez-Escudero, Alfonso; Carvajal-González, Jose M; Fernández-Salguero, Pedro M; de Polavieja, Gonzalo G

2018-04-25

Animals can show very different behaviors even in isogenic populations, but the underlying mechanisms to generate this variability remain elusive. We use the zebrafish (Danio rerio) as a model to test the influence of histone modifications on behavior. We find that laboratory and isogenic zebrafish larvae show consistent individual behaviors when swimming freely in identical wells or in reaction to stimuli. This behavioral inter-individual variability is reduced when we impair the histone deacetylation pathway. Individuals with high levels of histone H4 acetylation, and specifically H4K12, behave similarly to the average of the population, but those with low levels deviate from it. More precisely, we find a set of genomic regions whose histone H4 acetylation is reduced with the distance between the individual and the average population behavior. We find evidence that this modulation depends on a complex of Yin-yang 1 (YY1) and histone deacetylase 1 (HDAC1) that binds to and deacetylates these regions. These changes are not only maintained at the transcriptional level but also amplified, as most target regions are located near genes encoding transcription factors. We suggest that stochasticity in the histone deacetylation pathway participates in the generation of genetic-independent behavioral inter-individual variability.

An integrated workflow to assess technical and biological variability of cell population frequencies in human peripheral blood by flow cytometry

PubMed Central

Burel, Julie G.; Qian, Yu; Arlehamn, Cecilia Lindestam; Weiskopf, Daniela; Zapardiel-Gonzalo, Jose; Taplitz, Randy; Gilman, Robert H.; Saito, Mayuko; de Silva, Aruna D.; Vijayanand, Pandurangan; Scheuermann, Richard H.; Sette, Alessandro; Peters, Bjoern

2016-01-01

In the context of large-scale human system immunology studies, controlling for technical and biological variability is crucial to ensure that experimental data support research conclusions. Here, we report on a universal workflow to evaluate both technical and biological variation in multiparameter flow cytometry, applied to the development of a 10-color panel to identify all major cell populations and T cell subsets in cryopreserved PBMC. Replicate runs from a control donation and comparison of different gating strategies assessed technical variability associated with each cell population and permitted the calculation of a quality control score. Applying our panel to a large collection of PBMC samples, we found that most cell populations showed low intra-individual variability over time. In contrast, certain subpopulations such as CD56 T cells and Temra CD4 T cells were associated with high inter-individual variability. Age but not gender had a significant effect on the frequency of several populations, with a drastic decrease in naïve T cells observed in older donors. Ethnicity also influenced a significant proportion of immune cell population frequencies, emphasizing the need to account for these co-variates in immune profiling studies. Finally, we exemplify the usefulness of our workflow by identifying a novel cell-subset signature of latent tuberculosis infection. Thus, our study provides a universal workflow to establish and evaluate any flow cytometry panel in systems immunology studies. PMID:28069807

A multi-segment foot model based on anatomically registered technical coordinate systems: method repeatability in pediatric feet.

PubMed

Saraswat, Prabhav; MacWilliams, Bruce A; Davis, Roy B

2012-04-01

Several multi-segment foot models to measure the motion of intrinsic joints of the foot have been reported. Use of these models in clinical decision making is limited due to lack of rigorous validation including inter-clinician, and inter-lab variability measures. A model with thoroughly quantified variability may significantly improve the confidence in the results of such foot models. This study proposes a new clinical foot model with the underlying strategy of using separate anatomic and technical marker configurations and coordinate systems. Anatomical landmark and coordinate system identification is determined during a static subject calibration. Technical markers are located at optimal sites for dynamic motion tracking. The model is comprised of the tibia and three foot segments (hindfoot, forefoot and hallux) and inter-segmental joint angles are computed in three planes. Data collection was carried out on pediatric subjects at two sites (Site 1: n=10 subjects by two clinicians and Site 2: five subjects by one clinician). A plaster mold method was used to quantify static intra-clinician and inter-clinician marker placement variability by allowing direct comparisons of marker data between sessions for each subject. Intra-clinician and inter-clinician joint angle variability were less than 4°. For dynamic walking kinematics, intra-clinician, inter-clinician and inter-laboratory variability were less than 6° for the ankle and forefoot, but slightly higher for the hallux. Inter-trial variability accounted for 2-4° of the total dynamic variability. Results indicate the proposed foot model reduces the effects of marker placement variability on computed foot kinematics during walking compared to similar measures in previous models. Copyright © 2011 Elsevier B.V. All rights reserved.

Instrument inter-comparison of glyoxal, methyl glyoxal and NO2 under simulated atmospheric conditions

NASA Astrophysics Data System (ADS)

Thalman, R.; Baeza-Romero, M. T.; Ball, S. M.; Borrás, E.; Daniels, M. J. S.; Goodall, I. C. A.; Henry, S. B.; Karl, T.; Keutsch, F. N.; Kim, S.; Mak, J.; Monks, P. S.; Muñoz, A.; Orlando, J.; Peppe, S.; Rickard, A. R.; Ródenas, M.; Sánchez, P.; Seco, R.; Su, L.; Tyndall, G.; Vázquez, M.; Vera, T.; Waxman, E.; Volkamer, R.

2014-08-01

glyoxal (0.58 < R2 < 0.68) than for glyoxal (0.79 < R2 < 0.99). The intercepts of correlations were insignificant for the most part; slopes varied by less than 5% for instruments that also measure NO2. For glyoxal and methyl glyoxal the slopes varied by less than 12% and 17% (both 3-sigma) between inherently calibrated instruments (i.e., calibration from knowledge of the absorption cross-section). We find a larger variability among in situ techniques that employ external calibration sources (75% to 90%, 3-sigma), and/or techniques that employ offline analysis. Our inter-comparison reveal existing differences in reports about precision and detection limits in the literature, and enables comparison on a common basis by observing a common airmass. Finally, we evaluate the influence of interfering species (e.g., NO2, O3 and H2O) of relevance in field and laboratory applications. Techniques now exist to conduct fast and accurate measurements of glyoxal at ambient concentrations, and methyl glyoxal under simulated conditions. However, techniques to measure methyl glyoxal at ambient concentrations remain a challenge, and would be desirable.

Inter-Annual and Shorter-Term Variability in Physical and Biological Characteristics Across Barrow Canyon in August - September 2005-2014

NASA Astrophysics Data System (ADS)

Ashjian, C. J.; Okkonen, S. R.; Campbell, R. G.; Alatalo, P.

2014-12-01

Late summer physical and biological conditions along a 37-km transect crossing Barrow Canyon have been described for the past ten years as part of an ongoing program, supported by multiple funding sources including the NSF AON, focusing on inter-annual variability and the formation of a bowhead whale feeding hotspot near Barrow. These repeated transects (at least two per year, separated in time by days-weeks) provide an opportunity to assess the inter-annual and shorter term (days-weeks) changes in hydrographic structure, ocean temperature, current velocity and transport, chlorophyll fluorescence, nutrients, and micro- and mesozooplankton community composition and abundance. Inter-annual variability in all properties was high and was associated with larger scale, meteorological forcing. Shorter-term variability could also be high but was strongly influenced by changes in local wind forcing. The sustained sampling at this location provided critical measures of inter-annual variability that should permit detection of longer-term trends that are associated with ongoing climate change.

77 FR 66178 - Sensors and Instrumentation Technical Advisory Committee; Notice of Partially Closed Meeting...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-02

... DEPARTMENT OF COMMERCE Bureau of Industry and Security Sensors and Instrumentation Technical Advisory Committee; Notice of Partially Closed Meeting; Rescheduled The Sensors and Instrumentation... that affect the level of export controls applicable to sensors [[Page 66179

Approaches for modeling within subject variability in pharmacometric count data analysis: dynamic inter-occasion variability and stochastic differential equations.

PubMed

Deng, Chenhui; Plan, Elodie L; Karlsson, Mats O

2016-06-01

Parameter variation in pharmacometric analysis studies can be characterized as within subject parameter variability (WSV) in pharmacometric models. WSV has previously been successfully modeled using inter-occasion variability (IOV), but also stochastic differential equations (SDEs). In this study, two approaches, dynamic inter-occasion variability (dIOV) and adapted stochastic differential equations, were proposed to investigate WSV in pharmacometric count data analysis. These approaches were applied to published count models for seizure counts and Likert pain scores. Both approaches improved the model fits significantly. In addition, stochastic simulation and estimation were used to explore further the capability of the two approaches to diagnose and improve models where existing WSV is not recognized. The results of simulations confirmed the gain in introducing WSV as dIOV and SDEs when parameters vary randomly over time. Further, the approaches were also informative as diagnostics of model misspecification, when parameters changed systematically over time but this was not recognized in the structural model. The proposed approaches in this study offer strategies to characterize WSV and are not restricted to count data.

Nonsense-mediated mRNA decay: inter-individual variability and human disease

PubMed Central

Nguyen, Lam Son; Wilkinson, Miles; Gecz, Jozef

2013-01-01

Nonsense-Mediated mRNA Decay (NMD) is a regulatory pathway that functions to degrade transcripts containing premature termination codons (PTCs) and to maintain normal transcriptome homeostasis. Nonsense and frameshift mutations that generate PTCs cause approximately one-third of all known human genetic diseases and thus NMD has a potentially important role in human disease. In genetic disorders in which the affected genes carry PTC-generating mutations, NMD acts as a double-edge sword. While it can benefit the patient by degrading PTC-containing mRNAs that encode detrimental, dominant-negative truncated proteins, it can also make the disease worse when a PTC-containing mRNA is degraded that encodes a mutant but still functional protein. There is evidence that the magnitude of NMD varies between individuals, which, in turn, has been shown to correlate with both clinical presentations and the patients’ responses to drugs that promote read-through of PTCs. In this review, we examine the evidence supporting the existence of inter-individual variability in NMD efficiency and discuss the genetic factors that underlie this variability. We propose that inter-individual variability in NMD efficiency is a common phenomenon in human populations and that an individual’s NMD efficiency should be taken into consideration when testing, developing, and making therapeutic decisions for diseases caused by genes harboring PTCs. PMID:24239855

Inter-observer variability within BI-RADS and RANZCR mammographic density assessment schemes

NASA Astrophysics Data System (ADS)

Damases, Christine N.; Mello-Thoms, Claudia; McEntee, Mark F.

2016-03-01

This study compares variability associated with two visual mammographic density (MD) assessment methods using two separate samples of radiologists. The image test-set comprised of images obtained from 20 women (age 42-89 years). The images were assessed for their MD by twenty American Board of Radiology (ABR) examiners and twenty-six radiologists registered with the Royal Australian and New Zealand College of Radiologists (RANZCR). Images were assessed using the same technology and conditions, however the ABR radiologists used the BI-RADS and the RANZCR radiologists used the RANZCR breast density synoptic. Both scales use a 4-point assessment. The images were then grouped as low- and high-density; low including BIRADS 1 and 2 or RANZCR 1 and 2 and high including BI-RADS 3 and 4 or RANZCR 3 and 4. Four-point BI-RADS and RANZCR showed no or negligible correlation (ρ=-0.029 p<0.859). The average inter-observer agreement on the BI-RADS scale had a Kappa of 0.565; [95% CI = 0.519 - 0.610], and ranged between 0.328-0.669 while the inter-observer agreement using the RANZCR scale had a Kappa of 0.360; [95% CI = 0.308 - 0.412] and a range of 0.078-0.499. Our findings show a wider range of inter-observer variability among RANZCR registered radiologists than the ABR examiners.

Measuring the effect of inter-study variability on estimating prediction error.

PubMed

Ma, Shuyi; Sung, Jaeyun; Magis, Andrew T; Wang, Yuliang; Geman, Donald; Price, Nathan D

2014-01-01

The biomarker discovery field is replete with molecular signatures that have not translated into the clinic despite ostensibly promising performance in predicting disease phenotypes. One widely cited reason is lack of classification consistency, largely due to failure to maintain performance from study to study. This failure is widely attributed to variability in data collected for the same phenotype among disparate studies, due to technical factors unrelated to phenotypes (e.g., laboratory settings resulting in "batch-effects") and non-phenotype-associated biological variation in the underlying populations. These sources of variability persist in new data collection technologies. Here we quantify the impact of these combined "study-effects" on a disease signature's predictive performance by comparing two types of validation methods: ordinary randomized cross-validation (RCV), which extracts random subsets of samples for testing, and inter-study validation (ISV), which excludes an entire study for testing. Whereas RCV hardwires an assumption of training and testing on identically distributed data, this key property is lost in ISV, yielding systematic decreases in performance estimates relative to RCV. Measuring the RCV-ISV difference as a function of number of studies quantifies influence of study-effects on performance. As a case study, we gathered publicly available gene expression data from 1,470 microarray samples of 6 lung phenotypes from 26 independent experimental studies and 769 RNA-seq samples of 2 lung phenotypes from 4 independent studies. We find that the RCV-ISV performance discrepancy is greater in phenotypes with few studies, and that the ISV performance converges toward RCV performance as data from additional studies are incorporated into classification. We show that by examining how fast ISV performance approaches RCV as the number of studies is increased, one can estimate when "sufficient" diversity has been achieved for learning a molecular

SU-E-J-266: Cone Beam Computed Tomography (CBCT) Inter-Scan and Inter-Observer Tumor Volume Variability Assessment in Patients Treated with Stereotactic Body Radiation Therapy (SBRT) for Early Stage Non-Small Cell Lung Cancer (NSCLC)

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

Hou, Y; Aileen, C; Kozono, D

Purpose: Quantification of volume changes on CBCT during SBRT for NSCLC may provide a useful radiological marker for radiation response and adaptive treatment planning, but the reproducibility of CBCT volume delineation is a concern. This study is to quantify inter-scan/inter-observer variability in tumor volume delineation on CBCT. Methods: Twenty earlystage (stage I and II) NSCLC patients were included in this analysis. All patients were treated with SBRT with a median dose of 54 Gy in 3 to 5 fractions. Two physicians independently manually contoured the primary gross tumor volume on CBCTs taken immediately before SBRT treatment (Pre) and after themore » same SBRT treatment (Post). Absolute volume differences (AVD) were calculated between the Pre and Post CBCTs for a given treatment to quantify inter-scan variability, and then between the two observers for a given CBCT to quantify inter-observer variability. AVD was also normalized with respect to average volume to obtain relative volume differences (RVD). Bland-Altman approach was used to evaluate variability. All statistics were calculated with SAS version 9.4. Results: The 95% limit of agreement (mean ± 2SD) on AVD and RVD measurements between Pre and Post scans were −0.32cc to 0.32cc and −0.5% to 0.5% versus −1.9 cc to 1.8 cc and −15.9% to 15.3% for the two observers respectively. The 95% limit of agreement of AVD and RVD between the two observers were −3.3 cc to 2.3 cc and −42.4% to 28.2% respectively. The greatest variability in inter-scan RVD was observed with very small tumors (< 5 cc). Conclusion: Inter-scan variability in RVD is greatest with small tumors. Inter-observer variability was larger than inter-scan variability. The 95% limit of agreement for inter-observer and inter-scan variability (∼15–30%) helps define a threshold for clinically meaningful change in tumor volume to assess SBRT response, with larger thresholds needed for very small tumors. Part of the work was funded by a

Dynamic modal estimation using instrumental variables

NASA Technical Reports Server (NTRS)

Salzwedel, H.

1980-01-01

A method to determine the modes of dynamical systems is described. The inputs and outputs of a system are Fourier transformed and averaged to reduce the error level. An instrumental variable method that estimates modal parameters from multiple correlations between responses of single input, multiple output systems is applied to estimate aircraft, spacecraft, and off-shore platform modal parameters.

Inter- annual variability of water vapor over an equatorial coastal station using Microwave Radiometer observations.

NASA Astrophysics Data System (ADS)

Renju, Ramachandran Pillai; Uma, K. N.; Krishna Moorthy, K.; Mathew, Nizy; Raju C, Suresh

The south-western region of the Indian peninsula is the gateway of Indian summer monsoon. This region experiences continuous monsoon rain for a longer period of about six months from June to November. The amount of water vapor variability is one of the important parameters to study the onset, active and break phases of the monsoon. Keeping this in view, a multi-frequency Microwave Radiometer Profiler (MRP) has been made operational for continuous measurements of water vapor over an equatorial coastal station Thiruvananthapuram (8.5(°) N, 76.9(°) E) since April 2010. The MRP estimated precipitable water vapor (PWV) for different seasons including monsoon periods have been evaluated by comparing with the collocated GPS derived water vapor and radiosonde measurements. The diurnal, seasonal and inter annual variation of water vapor has been studied for the last four years (2010-2013) over this station. The significant diurnal variability of water vapor is found only during the winter and pre-monsoon periods (Dec -April). The vertical distribution of water vapour is studied in order to understand its variability especially during the onset of monsoon. During the building up of south-west monsoon, the specific humidity increases to ˜ 10g/kg in the altitude range of 4-6 km and consistently maintained it throughout the active spells and reduces to below 2g/kg during break spells of monsoon. The instrument details and the results will be presented.

Technical basis for implementation of remote reading capabilities for radiological control instruments at tank farms

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

PIERSON, R.M.

1999-10-27

This document provides the technical basis for use of remote reading capabilities with radiological control instruments at River Protection Project facilities. The purpose of this document is to evaluate applications of remote reading capabilities with Radiological Control instrumentation to allow continuous monitoring of radiation dose rates at River Protection Project (RPP) facilities. In addition this document provides a technical basis and implementing guidelines for remote monitoring of dose rates and their potential contribution to maintaining radiation exposures ALARA.

Inter-annual and spatial variability in hillslope runoff and mercury flux during spring snowmelt.

PubMed

Haynes, Kristine M; Mitchell, Carl P J

2012-08-01

Spring snowmelt is an important period of mercury (Hg) export from watersheds. Limited research has investigated the potential effects of climate variability on hydrologic and Hg fluxes during spring snowmelt. The purpose of this research was to assess the potential impacts of inter-annual climate variability on Hg mobility in forested uplands, as well as spatial variability in hillslope hydrology and Hg fluxes. We compared hydrological flows, Hg and solute mobility from three adjacent hillslopes in the S7 watershed of the Marcell Experimental Forest, Minnesota during two very different spring snowmelt periods: one following a winter (2009-2010) with severely diminished snow accumulation (snow water equivalent (SWE) = 48 mm) with an early melt, and a second (2010-2011) with significantly greater winter snow accumulation (SWE = 98 mm) with average to late melt timing. Observed inter-annual differences in total Hg (THg) and dissolved organic carbon (DOC) yields were predominantly flow-driven, as the proportion by which solute yields increased was the same as the increase in runoff. Accounting for inter-annual differences in flow, there was no significant difference in THg and DOC export between the two snowmelt periods. The spring 2010 snowmelt highlighted the important contribution of melting soil frost in the timing of a considerable portion of THg exported from the hillslope, accounting for nearly 30% of the THg mobilized. Differences in slope morphology and soil depths to the confining till layer were important in controlling the large observed spatial variability in hydrological flowpaths, transmissivity feedback responses, and Hg flux trends across the adjacent hillslopes.

The impact of inter-annual rainfall variability on food production in the Ganges basin

NASA Astrophysics Data System (ADS)

Siderius, Christian; Biemans, Hester; van Walsum, Paul; hellegers, Petra; van Ierland, Ekko; Kabat, Pavel

2014-05-01

Rainfall variability is expected to increase in the coming decades as the world warms. Especially in regions already water stressed, a higher rainfall variability will jeopardize food security. Recently, the impact of inter-annual rainfall variability has received increasing attention in regional to global analysis on water availability and food security. But the description of the dynamics behind it is still incomplete in most models. Contemporary land surface and hydrological models used for such analyses describe variability in production primarily as a function of yield, a process driven by biophysical parameters, thereby neglecting yearly variations in cropped area, a process driven largely by management decisions. Agricultural statistics for northern India show that the latter process could explain up to 40% of the observed inter-annual variation in food production in various states. We added a simple dynamic land use decision module to a land surface model (LPJmL) and analyzed to what extent this improved the estimation of variability in food production. Using this improved modelling framework we then assessed if and at which scale rainfall variability affects meeting the food self-sufficiency threshold. Early results for the Ganges Basin indicate that, while on basin level variability in crop production is still relatively low, several districts and states are highly affected (RSTD > 50%). Such insight can contribute to better recommendations on the most effective measures, at the most appropriate scale, to buffer variability in food production.

Development from childhood to adulthood increases morphological and functional inter-individual variability in the right superior temporal cortex.

PubMed

Bonte, Milene; Frost, Martin A; Rutten, Sanne; Ley, Anke; Formisano, Elia; Goebel, Rainer

2013-12-01

We study the developmental trajectory of morphology and function of the superior temporal cortex (STC) in children (8-9 years), adolescents (14-15 years) and young adults. We analyze cortical surface landmarks and functional MRI (fMRI) responses to voices, other natural categories and tones and examine how hemispheric asymmetry and inter-subject variability change across age. Our results show stable morphological asymmetries across age groups, including a larger left planum temporale and a deeper right superior temporal sulcus. fMRI analyses show that a rightward lateralization for voice-selective responses is present in all groups but decreases with age. Furthermore, STC responses to voices change from being less selective and more spatially diffuse in children to highly selective and focal in adults. Interestingly, the analysis of morphological landmarks reveals that inter-subject variability increases during development in the right--but not in the left--STC. Similarly, inter-subject variability of cortically-realigned functional responses to voices, other categories and tones increases with age in the right STC. Our findings reveal asymmetric developmental changes in brain regions crucial for auditory and voice perception. The age-related increase of inter-subject variability in right STC suggests that anatomy and function of this region are shaped by unique individual developmental experiences. © 2013.

A statistical parts-based appearance model of inter-subject variability.

PubMed

Toews, Matthew; Collins, D Louis; Arbel, Tal

2006-01-01

In this article, we present a general statistical parts-based model for representing the appearance of an image set, applied to the problem of inter-subject MR brain image matching. In contrast with global image representations such as active appearance models, the parts-based model consists of a collection of localized image parts whose appearance, geometry and occurrence frequency are quantified statistically. The parts-based approach explicitly addresses the case where one-to-one correspondence does not exist between subjects due to anatomical differences, as parts are not expected to occur in all subjects. The model can be learned automatically, discovering structures that appear with statistical regularity in a large set of subject images, and can be robustly fit to new images, all in the presence of significant inter-subject variability. As parts are derived from generic scale-invariant features, the framework can be applied in a wide variety of image contexts, in order to study the commonality of anatomical parts or to group subjects according to the parts they share. Experimentation shows that a parts-based model can be learned from a large set of MR brain images, and used to determine parts that are common within the group of subjects. Preliminary results indicate that the model can be used to automatically identify distinctive features for inter-subject image registration despite large changes in appearance.

Effects of climatic factors and ecosystem responses on the inter-annual variability of evapotranspiration in a coniferous plantation in subtropical China.

PubMed

Xu, Mingjie; Wen, Xuefa; Wang, Huimin; Zhang, Wenjiang; Dai, Xiaoqin; Song, Jie; Wang, Yidong; Fu, Xiaoli; Liu, Yunfen; Sun, Xiaomin; Yu, Guirui

2014-01-01

Because evapotranspiration (ET) is the second largest component of the water cycle and a critical process in terrestrial ecosystems, understanding the inter-annual variability of ET is important in the context of global climate change. Eight years of continuous eddy covariance measurements (2003-2010) in a subtropical coniferous plantation were used to investigate the impacts of climatic factors and ecosystem responses on the inter-annual variability of ET. The mean and standard deviation of annual ET for 2003-2010 were 786.9 and 103.4 mm (with a coefficient of variation of 13.1%), respectively. The inter-annual variability of ET was largely created in three periods: March, May-June, and October, which are the transition periods between seasons. A set of look-up table approaches were used to separate the sources of inter-annual variability of ET. The annual ETs were calculated by assuming that (a) both the climate and ecosystem responses among years are variable (Vcli-eco), (b) the climate is variable but the ecosystem responses are constant (Vcli), and (c) the climate is constant but ecosystem responses are variable (Veco). The ETs that were calculated under the above assumptions suggested that the inter-annual variability of ET was dominated by ecosystem responses and that there was a negative interaction between the effects of climate and ecosystem responses. These results suggested that for long-term predictions of water and energy balance in global climate change projections, the ecosystem responses must be taken into account to better constrain the uncertainties associated with estimation.

Effects of Climatic Factors and Ecosystem Responses on the Inter-Annual Variability of Evapotranspiration in a Coniferous Plantation in Subtropical China

PubMed Central

Xu, Mingjie; Wen, Xuefa; Wang, Huimin; Zhang, Wenjiang; Dai, Xiaoqin; Song, Jie; Wang, Yidong; Fu, Xiaoli; Liu, Yunfen; Sun, Xiaomin; Yu, Guirui

2014-01-01

Because evapotranspiration (ET) is the second largest component of the water cycle and a critical process in terrestrial ecosystems, understanding the inter-annual variability of ET is important in the context of global climate change. Eight years of continuous eddy covariance measurements (2003–2010) in a subtropical coniferous plantation were used to investigate the impacts of climatic factors and ecosystem responses on the inter-annual variability of ET. The mean and standard deviation of annual ET for 2003–2010 were 786.9 and 103.4 mm (with a coefficient of variation of 13.1%), respectively. The inter-annual variability of ET was largely created in three periods: March, May–June, and October, which are the transition periods between seasons. A set of look-up table approaches were used to separate the sources of inter-annual variability of ET. The annual ETs were calculated by assuming that (a) both the climate and ecosystem responses among years are variable (Vcli-eco), (b) the climate is variable but the ecosystem responses are constant (Vcli), and (c) the climate is constant but ecosystem responses are variable (Veco). The ETs that were calculated under the above assumptions suggested that the inter-annual variability of ET was dominated by ecosystem responses and that there was a negative interaction between the effects of climate and ecosystem responses. These results suggested that for long-term predictions of water and energy balance in global climate change projections, the ecosystem responses must be taken into account to better constrain the uncertainties associated with estimation. PMID:24465610

Correlations of Handgrip Strength with Selected Hand-Arm-Anthropometric Variables in Indian Inter-university Female Volleyball Players

PubMed Central

Koley, Shyamal; Pal Kaur, Satinder

2011-01-01

Purpose The purpose of this study was to estimate the dominant handgrip strength and its correlations with some hand and arm anthropometric variables in 101 randomly selected Indian inter-university female volleyball players aged 18-25 years (mean age 20.52±1.40) from six Indian universities. Methods Three anthropometric variables, i.e. height, weight, BMI, two hand anthropometric variables, viz. right and left hand width and length, four arm anthropometric variables, i.e. upper arm length, lower arm length, upper extremity length, upper arm circumference and dominant right and non-dominant handgrip strength were measured among Indian inter-university female volleyball players by standard anthropometric techniques. Results The findings of the present study indicated that Indian female volleyball players had higher mean values in eleven variables and lesser mean values in two variables than their control counterparts, showing significant differences (P<0.032-0.001) in height (t=2.63), weight (t=8.66), left hand width (t=2.10), left and right hand length (t=9.99 and 10.40 respectively), right upper arm length (t=8.48), right forearm length (t=5.41), dominant (right) and non-dominant (left) handgrip strength (t=9.37 and 6.76 respectively). In female volleyball players, dominant handgrip strength had significantly positive correlations (P=0.01) with all the variables studied. Conclusion It may be concluded that dominant handgrip strength had strong positive correlations with all the variables studied in Indian inter-university female volleyball players. PMID:22375242

When to simulate and when to associate? Accounting for inter-talker variability in the speech signal.

PubMed

Trude, Alison M

2013-08-01

Pickering & Garrod's (P&G's) theory could be modified to describe how listeners rapidly incorporate context to generate predictions about speech despite inter-talker variability. However, in order to do so, the content of "impoverished" predicted percepts must be expanded to include phonetic information. Further, the way listeners identify and represent inter-talker differences and subsequently determine which prediction method to use would require further specification.

Patterns and controls of inter-annual variability in the terrestrial carbon budget

NASA Astrophysics Data System (ADS)

Marcolla, Barbara; Rödenbeck, Christian; Cescatti, Alessandro

2017-08-01

The terrestrial carbon fluxes show the largest variability among the components of the global carbon cycle and drive most of the temporal variations in the growth rate of atmospheric CO2. Understanding the environmental controls and trends of the terrestrial carbon budget is therefore essential to predict the future trajectories of the CO2 airborne fraction and atmospheric concentrations. In the present work, patterns and controls of the inter-annual variability (IAV) of carbon net ecosystem exchange (NEE) have been analysed using three different data streams: ecosystem-level observations from the FLUXNET database (La Thuile and 2015 releases), the MPI-MTE (model tree ensemble) bottom-up product resulting from the global upscaling of site-level fluxes, and the Jena CarboScope Inversion, a top-down estimate of surface fluxes obtained from observed CO2 concentrations and an atmospheric transport model. Consistencies and discrepancies in the temporal and spatial patterns and in the climatic and physiological controls of IAV were investigated between the three data sources. Results show that the global average of IAV at FLUXNET sites, quantified as the standard deviation of annual NEE, peaks in arid ecosystems and amounts to ˜ 120 gC m-2 y-1, almost 6 times more than the values calculated from the two global products (15 and 20 gC m-2 y-1 for MPI-MTE and the Jena Inversion, respectively). Most of the temporal variability observed in the last three decades of the MPI-MTE and Jena Inversion products is due to yearly anomalies, whereas the temporal trends explain only about 15 and 20 % of the variability, respectively. Both at the site level and on a global scale, the IAV of NEE is driven by the gross primary productivity and in particular by the cumulative carbon flux during the months when land acts as a sink. Altogether these results offer a broad view on the magnitude, spatial patterns and environmental drivers of IAV from a variety of data sources that can be

Econometrics in outcomes research: the use of instrumental variables.

PubMed

Newhouse, J P; McClellan, M

1998-01-01

We describe an econometric technique, instrumental variables, that can be useful in estimating the effectiveness of clinical treatments in situations when a controlled trial has not or cannot be done. This technique relies upon the existence of one or more variables that induce substantial variation in the treatment variable but have no direct effect on the outcome variable of interest. We illustrate the use of the technique with an application to aggressive treatment of acute myocardial infarction in the elderly.

Inter-annual Variability in Global Suspended Particulate Inorganic Carbon Inventory Using Space-based Measurements

NASA Astrophysics Data System (ADS)

Hopkins, J.; Balch, W. M.; Henson, S.; Poulton, A. J.; Drapeau, D.; Bowler, B.; Lubelczyk, L.

2016-02-01

Coccolithophores, the single celled phytoplankton that produce an outer covering of calcium carbonate coccoliths, are considered to be the greatest contributors to the global oceanic particulate inorganic carbon (PIC) pool. The reflective coccoliths scatter light back out from the ocean surface, enabling PIC concentration to be quantitatively estimated from ocean color satellites. Here we use datasets of AQUA MODIS PIC concentration from 2003-2014 (using the recently-revised PIC algorithm), as well as statistics on coccolithophore vertical distribution derived from cruises throughout the world ocean, to estimate the average global (surface and integrated) PIC standing stock and its associated inter-annual variability. In addition, we divide the global ocean into Longhurst biogeochemical provinces, update the PIC biomass statistics and identify those regions that have the greatest inter-annual variability and thus may exert the greatest influence on global PIC standing stock and the alkalinity pump.

Inter-annual variability of carbon fluxes in temperate forest ecosystems: effects of biotic and abiotic factors

NASA Astrophysics Data System (ADS)

Chen, M.; Keenan, T. F.; Hufkens, K.; Munger, J. W.; Bohrer, G.; Brzostek, E. R.; Richardson, A. D.

2014-12-01

Carbon dynamics in terrestrial ecosystems are influenced by both abiotic and biotic factors. Abiotic factors, such as variation in meteorological conditions, directly drive biophysical and biogeochemical processes; biotic factors, referring to the inherent properties of the ecosystem components, reflect the internal regulating effects including temporal dynamics and memory. The magnitude of the effect of abiotic and biotic factors on forest ecosystem carbon exchange has been suggested to vary at different time scales. In this study, we design and conduct a model-data fusion experiment to investigate the role and relative importance of the biotic and abiotic factors for inter-annual variability of the net ecosystem CO2 exchange (NEE) of temperate deciduous forest ecosystems in the Northeastern US. A process-based model (FöBAAR) is parameterized at four eddy-covariance sites using all available flux and biometric measurements. We conducted a "transplant" modeling experiment, that is, cross- site and parameter simulations with different combinations of site meteorology and parameters. Using wavelet analysis and variance partitioning techniques, analysis of model predictions identifies both spatial variant and spatially invariant parameters. Variability of NEE was primarily modulated by gross primary productivity (GPP), with relative contributions varying from hourly to yearly time scales. The inter-annual variability of GPP and NEE is more regulated by meteorological forcing, but spatial variability in certain model parameters (biotic response) has more substantial effects on the inter-annual variability of ecosystem respiration (Reco) through the effects on carbon pools. Both the biotic and abiotic factors play significant roles in modulating the spatial and temporal variability in terrestrial carbon cycling in the region. Together, our study quantifies the relative importance of both, and calls for better understanding of them to better predict regional CO2

Transferability and inter-laboratory variability assessment of the in vitro bovine oocyte fertilization test.

PubMed

Tessaro, Irene; Modina, Silvia C; Crotti, Gabriella; Franciosi, Federica; Colleoni, Silvia; Lodde, Valentina; Galli, Cesare; Lazzari, Giovanna; Luciano, Alberto M

2015-01-01

The dramatic increase in the number of animals required for reproductive toxicity testing imposes the validation of alternative methods to reduce the use of laboratory animals. As we previously demonstrated for in vitro maturation test of bovine oocytes, the present study describes the transferability assessment and the inter-laboratory variability of an in vitro test able to identify chemical effects during the process of bovine oocyte fertilization. Eight chemicals with well-known toxic properties (benzo[a]pyrene, busulfan, cadmium chloride, cycloheximide, diethylstilbestrol, ketoconazole, methylacetoacetate, mifepristone/RU-486) were tested in two well-trained laboratories. The statistical analysis demonstrated no differences in the EC50 values for each chemical in within (inter-runs) and in between-laboratory variability of the proposed test. We therefore conclude that the bovine in vitro fertilization test could advance toward the validation process as alternative in vitro method and become part of an integrated testing strategy in order to predict chemical hazards on mammalian fertility. Copyright © 2015 Elsevier Inc. All rights reserved.

Use of allele scores as instrumental variables for Mendelian randomization

PubMed Central

Burgess, Stephen; Thompson, Simon G

2013-01-01

Background An allele score is a single variable summarizing multiple genetic variants associated with a risk factor. It is calculated as the total number of risk factor-increasing alleles for an individual (unweighted score), or the sum of weights for each allele corresponding to estimated genetic effect sizes (weighted score). An allele score can be used in a Mendelian randomization analysis to estimate the causal effect of the risk factor on an outcome. Methods Data were simulated to investigate the use of allele scores in Mendelian randomization where conventional instrumental variable techniques using multiple genetic variants demonstrate ‘weak instrument’ bias. The robustness of estimates using the allele score to misspecification (for example non-linearity, effect modification) and to violations of the instrumental variable assumptions was assessed. Results Causal estimates using a correctly specified allele score were unbiased with appropriate coverage levels. The estimates were generally robust to misspecification of the allele score, but not to instrumental variable violations, even if the majority of variants in the allele score were valid instruments. Using a weighted rather than an unweighted allele score increased power, but the increase was small when genetic variants had similar effect sizes. Naive use of the data under analysis to choose which variants to include in an allele score, or for deriving weights, resulted in substantial biases. Conclusions Allele scores enable valid causal estimates with large numbers of genetic variants. The stringency of criteria for genetic variants in Mendelian randomization should be maintained for all variants in an allele score. PMID:24062299

78 FR 17871 - Changes To Implement the Technical Corrections to the Leahy-Smith America Invents Act as to Inter...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-25

... rule eliminates the nine-month ``dead zone'' for filing an inter partes review petition challenging a..., section 1(d) of the AIA Technical Corrections Act and this final rule eliminate the nine-month ``dead zone... the nine-month ``dead zone'' as to first-to-invent patents and reissue patents. Costs and Benefits...

Data Combination and Instrumental Variables in Linear Models

ERIC Educational Resources Information Center

Khawand, Christopher

2012-01-01

Instrumental variables (IV) methods allow for consistent estimation of causal effects, but suffer from poor finite-sample properties and data availability constraints. IV estimates also tend to have relatively large standard errors, often inhibiting the interpretability of differences between IV and non-IV point estimates. Lastly, instrumental…

Seasonal and inter-annual variability of the net ecosystem CO2 exchange of a temperate mountain grassland: effects of climate and management.

PubMed

Wohlfahrt, Georg; Hammerle, Albin; Haslwanter, Alois; Bahn, Michael; Tappeiner, Ulrike; Cernusca, Alexander

2008-04-27

The role and relative importance of climate and cutting for the seasonal and inter-annual variability of the net ecosystem CO 2 (NEE) of a temperate mountain grassland was investigated. Eddy covariance CO 2 flux data and associated measurements of the green area index and the major environmental driving forces acquired during 2001-2006 at the study site Neustift (Austria) were analyzed. Driven by three cutting events per year which kept the investigated grassland in a stage of vigorous growth, the seasonal variability of NEE was primarily modulated by gross primary productivity (GPP). The role of environmental parameters in modulating the seasonal variability of NEE was obscured by the strong response of GPP to changes in the amount of green area, as well as the cutting-mediated decoupling of phenological development and the seasonal course of climate drivers. None of the climate and management metrics examined was able to explain the inter-annual variability of annual NEE. This is thought to result from (1) a high covariance between GPP and ecosystem respiration (R eco ) at the annual time scale which results in a comparatively small inter-annual variation of NEE, (2) compensating effects between carbon exchange during and outside the management period, and (3) changes in the biotic response to rather than the climate variables per se. GPP was more important in modulating inter-annual variations in NEE in spring and before the first and second cut, while R eco explained a larger fraction of the inter-annual variability of NEE during the remaining, in particular the post-cut, periods.

Inter-annual variability of the Mediterranean thermohaline circulation in Med-CORDEX simulations

NASA Astrophysics Data System (ADS)

Vittoria Struglia, Maria; Adani, Mario; Carillo, Adriana; Pisacane, Giovanna; Sannino, Gianmaria; Beuvier, Jonathan; Lovato, Tomas; Sevault, Florence; Vervatis, Vassilios

2016-04-01

Recent atmospheric reanalysis products, such as ERA40 and ERA-interim, and their regional dynamical downscaling prompted the HyMeX/Med-CORDEX community to perform hind-cast simulations of the Mediterranean Sea, giving the opportunity to evaluate the response of different ocean models to a realistic inter-annual atmospheric forcing. Ocean numerical modeling studies have been steadily improving over the last decade through hind-cast processing, and are complementary to observations in studying the relative importance of the mechanisms playing a role in ocean variability, either external forcing or internal ocean variability. This work presents a review and an inter-comparison of the most recent hind-cast simulations of the Mediterranean Sea Circulation, produced in the framework of the Med-CORDEX initiative, at resolutions spanning from 1/8° to 1/16°. The richness of the simulations available for this study is exploited to address the effects of increasing resolution, both of models and forcing, the initialization procedure, and the prescription of the atmospheric boundary conditions, which are particularly relevant in order to model a realistic THC, in the perspective of fully coupled regional ocean-atmosphere models. The mean circulation is well reproduced by all the simulations. However, it can be observed that the horizontal resolution of both atmospheric forcing and ocean model plays a fundamental role in the reproduction of some specific features of both sub-basins and important differences can be observed among low and high resolution atmosphere forcing. We analyze the mean circulation on both the long-term and decadal time scale, and the represented inter-annual variability of intermediate and deep water mass formation processes in both the Eastern and Western sub-basins, finding that models agree with observations in correspondence of specific events, such as the 1992-1993 Eastern Mediterranean Transient, and the 2005-2006 event in the Gulf of Lion. Long

Bias and Bias Correction in Multi-Site Instrumental Variables Analysis of Heterogeneous Mediator Effects

ERIC Educational Resources Information Center

Reardon, Sean F.; Unlu, Faith; Zhu, Pei; Bloom, Howard

2013-01-01

We explore the use of instrumental variables (IV) analysis with a multi-site randomized trial to estimate the effect of a mediating variable on an outcome in cases where it can be assumed that the observed mediator is the only mechanism linking treatment assignment to outcomes, as assumption known in the instrumental variables literature as the…

Radiometric calibration stability and inter-calibration of solar-band instruments in orbit using the moon

USGS Publications Warehouse

Stone, T.C.

2008-01-01

With the increased emphasis on monitoring the Earth's climate from space, more stringent calibration requirements are being placed on the data products from remote sensing satellite instruments. Among these are stability over decade-length time scales and consistency across sensors and platforms. For radiometer instruments in the solar reflectance wavelength range (visible to shortwave infrared), maintaining calibration on orbit is difficult due to the lack of absolute radiometric standards suitable for flight use. The Moon presents a luminous source that can be viewed by all instruments in Earth orbit. Considered as a solar diffuser, the lunar surface is exceedingly stable. The chief difficulty with using the Moon is the strong variations in the Moon's brightness with illumination and viewing geometry. This mandates the use of a photometric model to compare lunar observations, either over time by the same instrument or between instruments. The U.S. Geological Survey in Flagstaff, Arizona, under NASA sponsorship, has developed a model for the lunar spectral irradiance that explicitly accounts for the effects of phase, the lunar librations, and the lunar surface reflectance properties. The model predicts variations in the Moon's brightness with precision ???1% over a continuous phase range from eclipse to the quarter lunar phases. Given a time series of Moon observations taken by an instrument, the geometric prediction capability of the lunar irradiance model enables sensor calibration stability with sub-percent per year precision. Cross-calibration of instruments with similar passbands can be achieved with precision comparable to the model precision. Although the Moon observations used for intercomparison can be widely separated in phase angle and/or time, SeaWiFS and MODIS have acquired lunar views closely spaced in time. These data provide an example to assess inter-calibration biases between these two instruments.

47 CFR 25.279 - Inter-satellite service.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Technical Operations § 25.279 Inter-satellite service. (a) Any satellite communicating with other space stations may use frequencies in the inter-satellite service as indicated in § 2.106 of this chapter. This...

47 CFR 25.279 - Inter-satellite service.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Technical Operations § 25.279 Inter-satellite service. (a) Any satellite communicating with other space stations may use frequencies in the inter-satellite service as indicated in § 2.106 of this chapter. This...

47 CFR 25.279 - Inter-satellite service.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Technical Operations § 25.279 Inter-satellite service. (a) Any satellite communicating with other space stations may use frequencies in the inter-satellite service as indicated in § 2.106 of this chapter. This...

47 CFR 25.279 - Inter-satellite service.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Technical Operations § 25.279 Inter-satellite service. (a) Any satellite communicating with other space stations may use frequencies in the inter-satellite service as indicated in § 2.106 of this chapter. This...

47 CFR 25.279 - Inter-satellite service.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Technical Operations § 25.279 Inter-satellite service. (a) Any satellite communicating with other space stations may use frequencies in the inter-satellite service as indicated in § 2.106 of this chapter. This...

VO2 and VCO2 variabilities through indirect calorimetry instrumentation.

PubMed

Cadena-Méndez, Miguel; Escalante-Ramírez, Boris; Azpiroz-Leehan, Joaquín; Infante-Vázquez, Oscar

2013-01-01

The aim of this paper is to understand how to measure the VO2 and VCO2 variabilities in indirect calorimetry (IC) since we believe they can explain the high variation in the resting energy expenditure (REE) estimation. We propose that variabilities should be separately measured from the VO2 and VCO2 averages to understand technological differences among metabolic monitors when they estimate the REE. To prove this hypothesis the mixing chamber (MC) and the breath-by-breath (BbB) techniques measured the VO2 and VCO2 averages and their variabilities. Variances and power spectrum energies in the 0-0.5 Hertz band were measured to establish technique differences in steady and non-steady state. A hybrid calorimeter with both IC techniques studied a population of 15 volunteers that underwent the clino-orthostatic maneuver in order to produce the two physiological stages. The results showed that inter-individual VO2 and VCO2 variabilities measured as variances were negligible using the MC while variabilities measured as spectral energies using the BbB underwent 71 and 56% (p < 0.05), increase respectively. Additionally, the energy analysis showed an unexpected cyclic rhythm at 0.025 Hertz only during the orthostatic stage, which is new physiological information, not reported previusly. The VO2 and VCO2 inter-individual averages increased to 63 and 39% by the MC (p < 0.05) and 32 and 40% using the BbB (p < 0.1), respectively, without noticeable statistical differences among techniques. The conclusions are: (a) metabolic monitors should simultaneously include the MC and the BbB techniques to correctly interpret the steady or non-steady state variabilities effect in the REE estimation, (b) the MC is the appropriate technique to compute averages since it behaves as a low-pass filter that minimizes variances, (c) the BbB is the ideal technique to measure the variabilities since it can work as a high-pass filter to generate discrete time series able to accomplish

Censored Quantile Instrumental Variable Estimates of the Price Elasticity of Expenditure on Medical Care.

PubMed

Kowalski, Amanda

2016-01-02

Efforts to control medical care costs depend critically on how individuals respond to prices. I estimate the price elasticity of expenditure on medical care using a censored quantile instrumental variable (CQIV) estimator. CQIV allows estimates to vary across the conditional expenditure distribution, relaxes traditional censored model assumptions, and addresses endogeneity with an instrumental variable. My instrumental variable strategy uses a family member's injury to induce variation in an individual's own price. Across the conditional deciles of the expenditure distribution, I find elasticities that vary from -0.76 to -1.49, which are an order of magnitude larger than previous estimates.

The influence of intra- and inter-annual meteorological variability on dengue transmission: a multi-level modeling analysis

NASA Astrophysics Data System (ADS)

Wen, Tzai-Hung; Chen, Tzu-Hsin

2017-04-01

Dengue fever is one of potentially life-threatening mosquito-borne diseases and IPCC Fifth Assessment Report (AR5) has confirmed that dengue incidence is sensitive to the critical weather conditions, such as effects of temperature. However, previous literature focused on the effects of monthly or weekly average temperature or accumulative precipitation on dengue incidence. The influence of intra- and inter-annual meteorological variability on dengue outbreak is under investigated. The purpose of the study focuses on measuring the effect of the intra- and inter-annual variations of temperature and precipitation on dengue outbreaks. We developed the indices of intra-annual temperature variability are maximum continuity, intermittent, and accumulation of most suitable temperature (MST) for dengue vectors; and also the indices of intra-annual precipitation variability, including the measure of continuity of wetness or dryness during a pre-epidemic period; and rainfall intensity during an epidemic period. We used multi-level modeling to investigate the intra- and inter-annual meteorological variations on dengue outbreaks in southern Taiwan from 1998-2015. Our results indicate that accumulation and maximum continuity of MST are more significant than average temperature on dengue outbreaks. The effect of continuity of wetness during the pre-epidemic period is significantly more positive on promoting dengue outbreaks than the rainfall effect during the epidemic period. Meanwhile, extremely high or low rainfall density during an epidemic period do not promote the spread of dengue epidemics. Our study differentiates the effects of intra- and inter-annual meteorological variations on dengue outbreaks and also provides policy implications for further dengue control under the threats of climate change. Keywords: dengue fever, meteorological variations, multi-level model

Intra- and inter-population variability and evaluation of the physical development of a young generation.

PubMed

Yampolskaya, Yulia A

2005-07-01

This study is concerned with long-term anthropometric examinations of children and adolescents aged 3-17 years in Moscow (over 10,500 persons, longitudinal and cross-sectional). Population variability of physical development was analyzed by means of regional estimation tables, which were developed on the basis of a regression analysis (scale of the regression of body mass to body length within a range from M - 1sigmaR to M + 2 sigmaR) and used for individual and group diagnostics taking into account age and sex. Such an approach allowed for the determination of the dynamics of the variability of Moscow schoolchildren from decade to decade (inter-population variability) and variations due to social differences (intra-population variability).

[Inter-and intra-operator variability in the analysis of semen parameters: results from a quality control program].

PubMed

Daoud, Salima; Chakroun-Feki, Nozha; Sellami, Afifa; Ammar-Keskes, Leila; Rebai, Tarek

2016-01-01

Semen analysis is a key part of male infertility investigation. The necessity of quality management implementation in the andrology laboratory has been recognized in order to ensure the reliability of its results. The aim of this study was to evaluate intra- and inter-individual variability in the assessment of semen parameters in our laboratory through a quality control programme. Four participants from the laboratory with different experience levels have participated in this study. Semen samples of varying quality were assessed for sperm motility, concentration and morphology and the results were used to evaluate inter-participant variability. In addition, replicates of each semen sample were analyzed to determine intra-individual variability for semen parameters analysis. The average values of inter-participant coefficients of variation for sperm motility, concentration and morphology were 12.8%, 19.8% and 48.9% respectively. The mean intra-participant coefficients of variation were, respectively, 6.9%, 12.3% and 42.7% for sperm motility, concentration and morphology. Despite some random errors of under- or overestimation, the overall results remained within the limits of acceptability for all participants. Sperm morphology assessment was particularly influenced by the participant's level of experience. The present data emphasize the need for appropriate training of the laboratory staff and for regular participation in internal quality control programmes in order to improve the reliability of laboratory results.

An Analysis of Inter-annual Variability and Uncertainty of Continental Surface Heat Fluxes

NASA Astrophysics Data System (ADS)

Huang, S. Y.; Deng, Y.; Wang, J.

2016-12-01

The inter-annual variability and the corresponding uncertainty of land surface heat fluxes during the first decade of the 21st century are re-evaluated at continental scale based on the heat fluxes estimated by the maximum entropy production (MEP) model. The MEP model predicted heat fluxes are constrained by surface radiation fluxes, automatically satisfy surface energy balance, and are independent of temperature/moisture gradient, wind speed, and roughness lengths. The surface radiation fluxes and temperature data from Clouds and the Earth's Radiant Energy System and the surface specific humidity data from Modern-Era Retrospective analysis for Research and Applications were used to reproduce the global surface heat fluxes with land-cover data from the NASA Energy and Water cycle Study (NEWS). Our analysis shows that the annual means of continental latent heat fluxes have increasing trends associated with increasing trends in surface net radiative fluxes. The sensible heat fluxes also have increasing trends over most continents except for South America. Ground heat fluxes have little trends. The continental-scale analysis of the MEP fluxes are compared with other existing global surface fluxes data products and the implications of the results for inter-annual to decadal variability of regional surface energy budget are discussed.

Censored Quantile Instrumental Variable Estimates of the Price Elasticity of Expenditure on Medical Care

PubMed Central

Kowalski, Amanda

2015-01-01

Efforts to control medical care costs depend critically on how individuals respond to prices. I estimate the price elasticity of expenditure on medical care using a censored quantile instrumental variable (CQIV) estimator. CQIV allows estimates to vary across the conditional expenditure distribution, relaxes traditional censored model assumptions, and addresses endogeneity with an instrumental variable. My instrumental variable strategy uses a family member’s injury to induce variation in an individual’s own price. Across the conditional deciles of the expenditure distribution, I find elasticities that vary from −0.76 to −1.49, which are an order of magnitude larger than previous estimates. PMID:26977117

THAT INSTRUMENT IS LOUSY! IN SEARCH OF AGREEMENT WHEN USING INSTRUMENTAL VARIABLES ESTIMATION IN SUBSTANCE USE RESEARCH

PubMed Central

Popovici, Ioana

2009-01-01

SUMMARY The primary statistical challenge that must be addressed when using cross-sectional data to estimate the consequences of consuming addictive substances is the likely endogeneity of substance use. While economists are in agreement on the need to consider potential endogeneity bias and the value of instrumental variables estimation, the selection of credible instruments is a topic of heated debate in the field. Rather than attempt to resolve this debate, our paper highlights the diversity of judgments about what constitutes appropriate instruments for substance use based on a comprehensive review of the economics literature since 1990. We then offer recommendations related to the selection of reliable instruments in future studies. PMID:20029936

InterFacility communications technical document 1.1

DOT National Transportation Integrated Search

1996-04-01

InterFacility (IF) communications allows 2 adjacent air traffic control (ATC) facilities to communicate with each other. IF is simulated in TGF to allow whatever lab we are responding to (ARTS/NAS) to simulate communications with one or more adjacent...

Assessing the inter-observer variability of Computer-Aided Nodule Assessment and Risk Yield (CANARY) to characterize lung adenocarcinomas.

PubMed

Nakajima, Erica C; Frankland, Michael P; Johnson, Tucker F; Antic, Sanja L; Chen, Heidi; Chen, Sheau-Chiann; Karwoski, Ronald A; Walker, Ronald; Landman, Bennett A; Clay, Ryan D; Bartholmai, Brian J; Rajagopalan, Srinivasan; Peikert, Tobias; Massion, Pierre P; Maldonado, Fabien

2018-01-01

Lung adenocarcinoma (ADC), the most common lung cancer type, is recognized increasingly as a disease spectrum. To guide individualized patient care, a non-invasive means of distinguishing indolent from aggressive ADC subtypes is needed urgently. Computer-Aided Nodule Assessment and Risk Yield (CANARY) is a novel computed tomography (CT) tool that characterizes early ADCs by detecting nine distinct CT voxel classes, representing a spectrum of lepidic to invasive growth, within an ADC. CANARY characterization has been shown to correlate with ADC histology and patient outcomes. This study evaluated the inter-observer variability of CANARY analysis. Three novice observers segmented and analyzed independently 95 biopsy-confirmed lung ADCs from Vanderbilt University Medical Center/Nashville Veterans Administration Tennessee Valley Healthcare system (VUMC/TVHS) and the Mayo Clinic (Mayo). Inter-observer variability was measured using intra-class correlation coefficient (ICC). The average ICC for all CANARY classes was 0.828 (95% CI 0.76, 0.895) for the VUMC/TVHS cohort, and 0.852 (95% CI 0.804, 0.901) for the Mayo cohort. The most invasive voxel classes had the highest ICC values. To determine whether nodule size influenced inter-observer variability, an additional cohort of 49 sub-centimeter nodules from Mayo were also segmented by three observers, with similar ICC results. Our study demonstrates that CANARY ADC classification between novice CANARY users has an acceptably low degree of variability, and supports the further development of CANARY for clinical application.

Longitudinal Surveys of Australian Youth (LSAY): Derived Variables. Technical Report 64

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2012

2012-01-01

This technical report describes the 24 derived variables developed for users of the Longitudinal Surveys of Australian Youth (LSAY) data. The variables fall into the categories education, employment and social, and help to simplify the complexity of the LSAY data by providing useful indicators for analysis. To help LSAY data users understand and…

SU-G-206-07: Dual-Energy CT Inter- and Intra-Scanner Variability Within One Make and Model

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

Jacobsen, M; Wood, C; Cody, D

Purpose: It can be logistically quite difficult to scan patients on the same exact device for their repeat visits in multi-scanner facilities. The reliability between dual-energy CT scanners’ quantitative results is not known, nor is their individual repeatability. Therefore, we evaluated inter- and intra-scanner variability with respect to several key clinical quantitative metrics specific to dual-energy CT. Methods: Eleven identical GE HD-750 CT scanners in a busy clinical environment were used to perform dual-energy (DE) CT scans of a large elliptical quality control (QC) phantom (Gammex, Inc.; Middleton, WI) which contains many standard insert materials. The DE-QC phantom was scannedmore » bi-weekly during 2016; 3 to 4 scans were obtained from each scanner (a total of 35 data sets were used for analysis). Iodine accuracy for the 2mg/ml, 5mg/ml and 15mg/ml rods (from the Iodine(Water) image set) and soft tissue HU (40 HU based on NIST constants) from the 50keV data set were used to assess inter- and intra-scanner variability (standard deviation). Results: Intra-scanner variability average for 2mg/ml Iodine was 0.10 mg/ml (range 0.05–0.15 mg/ml), for 5mg/ml Iodine was 0.12 mg/ml (range 0.07–0.16 mg/ml), for 15 mg/ml Iodine was 0.25 mg/ml (range 0.16–0.37 mg/ml), and for the soft tissue inserts was 2.1 HU (range 1.8–2.6 HU). Inter-scanner variability average for 2mg/ml Iodine was 0.16 mg/ml (range 0.11–0.19 mg/ml), for 5mg/ml Iodine was 0.18 mg/ml (range 0.11–0.22 mg/ml), for 15 mg/ml Iodine was 0.35 mg/ml (range 0.23–0.44 mg/ml), and for the soft tissue inserts was 3.8 HU (range 3.1–4.5 HU). Conclusion: Intra-scanner variability for the iodine and soft tissue inserts averaged 3.1% and 5.2% respectively, and inter-scanner variability for these regions analyzed averaged 5.0% and 9.5%, respectively. Future work will include determination of smallest measurable change and acceptable limits for DE-CT scanner variability over longer time intervals

Informed palliative care in nursing homes through the interRAI Palliative Care instrument: a study protocol based on the Medical Research Council framework.

PubMed

Hermans, Kirsten; Spruytte, Nele; Cohen, Joachim; Van Audenhove, Chantal; Declercq, Anja

2014-12-05

Nursing homes are important locations for palliative care. Through comprehensive geriatric assessments (CGAs), evaluations can be made of palliative care needs of nursing home residents. The interRAI Palliative Care instrument (interRAI PC) is a CGA that evaluates diverse palliative care needs of adults in all healthcare settings. The evaluation results in Client Assessment Protocols (CAPs: indications of problems that need addressing) and Scales (e.g. Palliative Index for Mortality (PIM)) which can be used to design, evaluate and adjust care plans. This study aims to examine the effect of using the interRAI PC on the quality of palliative care in nursing homes. Additionally, it aims to evaluate the feasibility and validity of the interRAI PC. This study covers phases 0, I and II of the Medical Research Council (MRC) framework for designing and evaluating complex interventions, with a longitudinal, quasi-experimental pretest-posttest design and with mixed methods of evaluation. In phase 0, a systematic literature search is conducted. In phase I, the interRAI PC is adapted for use in Belgium and implemented on the BelRAI-website and a practical training is developed. In phase II, the intervention is tested in fifteen nursing homes. Participating nursing homes fill out the interRAI PC during one year for all residents receiving palliative care. Using a pretest-posttest design with quasi-random assignment to the intervention or control group, the effect of the interRAI PC on the quality of palliative care is evaluated with the Palliative care Outcome Scale (POS). Psychometric analysis is conducted to evaluate the predictive validity of the PIM and the convergent validity of the CAP 'Mood' of the interRAI PC. Qualitative data regarding the usability and face validity of the instrument are collected through focus groups, interviews and field notes. This is the first study to evaluate the validity and effect of the interRAI PC in nursing homes, following a methodology

Overview of intercalibration of satellite instruments

USGS Publications Warehouse

Chander, G.; Hewison, T.J.; Fox, N.; Wu, X.; Xiong, X.; Blackwell, W.J.

2013-01-01

Inter-calibration of satellite instruments is critical for detection and quantification of changes in the Earth’s environment, weather forecasting, understanding climate processes, and monitoring climate and land cover change. These applications use data from many satellites; for the data to be inter-operable, the instruments must be cross-calibrated. To meet the stringent needs of such applications requires that instruments provide reliable, accurate, and consistent measurements over time. Robust techniques are required to ensure that observations from different instruments can be normalized to a common scale that the community agrees on. The long-term reliability of this process needs to be sustained in accordance with established reference standards and best practices. Furthermore, establishing physical meaning to the information through robust Système International d'unités (SI) traceable Calibration and Validation (Cal/Val) is essential to fully understand the parameters under observation. The processes of calibration, correction, stability monitoring, and quality assurance need to be underpinned and evidenced by comparison with “peer instruments” and, ideally, highly calibrated in-orbit reference instruments. Inter-calibration between instruments is a central pillar of the Cal/Val strategies of many national and international satellite remote sensing organizations. Inter-calibration techniques as outlined in this paper not only provide a practical means of identifying and correcting relative biases in radiometric calibration between instruments but also enable potential data gaps between measurement records in a critical time series to be bridged. Use of a robust set of internationally agreed upon and coordinated inter-calibration techniques will lead to significant improvement in the consistency between satellite instruments and facilitate accurate monitoring of the Earth’s climate at uncertainty levels needed to detect and attribute the mechanisms

Determination of the anaerobic threshold in the pre-operative assessment clinic: inter-observer measurement error.

PubMed

Sinclair, R C F; Danjoux, G R; Goodridge, V; Batterham, A M

2009-11-01

The variability between observers in the interpretation of cardiopulmonary exercise tests may impact upon clinical decision making and affect the risk stratification and peri-operative management of a patient. The purpose of this study was to quantify the inter-reader variability in the determination of the anaerobic threshold (V-slope method). A series of 21 cardiopulmonary exercise tests from patients attending a surgical pre-operative assessment clinic were read independently by nine experienced clinicians regularly involved in clinical decision making. The grand mean for the anaerobic threshold was 10.5 ml O(2).kg body mass(-1).min(-1). The technical error of measurement was 8.1% (circa 0.9 ml.kg(-1).min(-1); 90% confidence interval, 7.4-8.9%). The mean absolute difference between readers was 4.5% with a typical random error of 6.5% (6.0-7.2%). We conclude that the inter-observer variability for experienced clinicians determining the anaerobic threshold from cardiopulmonary exercise tests is acceptable.

Developing and Validating the Socio-Technical Model in Ontology Engineering

NASA Astrophysics Data System (ADS)

Silalahi, Mesnan; Indra Sensuse, Dana; Giri Sucahyo, Yudho; Fadhilah Akmaliah, Izzah; Rahayu, Puji; Cahyaningsih, Elin

2018-03-01

This paper describes results from an attempt to develop a model in ontology engineering methodology and a way to validate the model. The approach to methodology in ontology engineering is from the point view of socio-technical system theory. Qualitative research synthesis is used to build the model using meta-ethnography. In order to ensure the objectivity of the measurement, inter-rater reliability method was applied using a multi-rater Fleiss Kappa. The results show the accordance of the research output with the diamond model in the socio-technical system theory by evidence of the interdependency of the four socio-technical variables namely people, technology, structure and task.

Inter-annual variability and long term predictability of exchanges through the Strait of Gibraltar

NASA Astrophysics Data System (ADS)

Boutov, Dmitri; Peliz, Álvaro; Miranda, Pedro M. A.; Soares, Pedro M. M.; Cardoso, Rita M.; Prieto, Laura; Ruiz, Javier; García-Lafuente, Jesus

2014-03-01

Inter-annual variability of calculated barotropic (netflow) and simulated baroclinic (inflow and outflow) exchanges through the Strait of Gibraltar is analyzed and their response to the main modes of atmospheric variability is investigated. Time series of the outflow obtained by high resolution simulations and estimated from in-situ Acoustic Doppler Current Profiler (ADCP) current measurements are compared. The time coefficients (TC) of the leading empirical orthogonal function (EOF) modes that describe zonal atmospheric circulation in the vicinity of the Strait (1st and 3rd of Sea-Level Pressure (SLP) and 1st of the wind) show significant covariance with the inflow and outflow. Based on these analyses, a regression model between these SLP TCs and outflow of the Mediterranean Water was developed. This regression outflow time series was compared with estimates based on current meter observations and the predictability and reconstruction of past exchange variability based on atmospheric pressure fields are discussed. The simple regression model seems to reproduce the outflow evolution fairly reasonably, with the exception of the year 2008, which is apparently anomalous without available physical explanation yet. The exchange time series show a reduced inter-annual variability (less than 1%, 2.6% and 3.1% of total 2-day variability, for netflow, inflow and outflow, respectively). From a statistical point of view no clear long-term tendencies were revealed. Anomalously high baroclinic fluxes are reported for the years of 2000-2001 that are coincident with strong impact on the Alboran Sea ecosystem. The origin of the anomalous flow is associated with a strong negative anomaly (~ - 9 hPa) in atmospheric pressure fields settled north of Iberian Peninsula and extending over the central Atlantic, favoring an increased zonal circulation in winter 2000/2001. These low pressure fields forced intense and durable westerly winds in the Gulf of Cadiz-Alboran system. The signal of

Testing concordance of instrumental variable effects in generalized linear models with application to Mendelian randomization

PubMed Central

Dai, James Y.; Chan, Kwun Chuen Gary; Hsu, Li

2014-01-01

Instrumental variable regression is one way to overcome unmeasured confounding and estimate causal effect in observational studies. Built on structural mean models, there has been considerale work recently developed for consistent estimation of causal relative risk and causal odds ratio. Such models can sometimes suffer from identification issues for weak instruments. This hampered the applicability of Mendelian randomization analysis in genetic epidemiology. When there are multiple genetic variants available as instrumental variables, and causal effect is defined in a generalized linear model in the presence of unmeasured confounders, we propose to test concordance between instrumental variable effects on the intermediate exposure and instrumental variable effects on the disease outcome, as a means to test the causal effect. We show that a class of generalized least squares estimators provide valid and consistent tests of causality. For causal effect of a continuous exposure on a dichotomous outcome in logistic models, the proposed estimators are shown to be asymptotically conservative. When the disease outcome is rare, such estimators are consistent due to the log-linear approximation of the logistic function. Optimality of such estimators relative to the well-known two-stage least squares estimator and the double-logistic structural mean model is further discussed. PMID:24863158

Inter-Individual Variability in Human Response to Low-Dose Ionizing Radiation, Final Report

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

Rocke, David

2016-08-01

In order to investigate inter-individual variability in response to low-dose ionizing radiation, we are working with three models, 1) in-vivo irradiated human skin, for which we have a realistic model, but with few subjects, all from a previous project, 2) ex-vivo irradiated human skin, for which we also have a realistic model, though with the limitations involved in keeping skin pieces alive in media, and 3) MatTek EpiDermFT skin plugs, which provides a more realistic model than cell lines, which is more controllable than human samples.

Inter-decadal variability of phytoplankton biomass along the coastal West Antarctic Peninsula.

PubMed

Kim, Hyewon; Ducklow, Hugh W; Abele, Doris; Ruiz Barlett, Eduardo M; Buma, Anita G J; Meredith, Michael P; Rozema, Patrick D; Schofield, Oscar M; Venables, Hugh J; Schloss, Irene R

2018-06-28

The West Antarctic Peninsula (WAP) is a climatically sensitive region where periods of strong warming have caused significant changes in the marine ecosystem and food-web processes. Tight coupling between phytoplankton and higher trophic levels implies that the coastal WAP is a bottom-up controlled system, where changes in phytoplankton dynamics may largely impact other food-web components. Here, we analysed the inter-decadal time series of year-round chlorophyll- a (Chl) collected from three stations along the coastal WAP: Carlini Station at Potter Cove (PC) on King George Island, Palmer Station on Anvers Island and Rothera Station on Adelaide Island. There were trends towards increased phytoplankton biomass at Carlini Station (PC) and Palmer Station, while phytoplankton biomass declined significantly at Rothera Station over the studied period. The impacts of two relevant climate modes to the WAP, the El Niño-Southern Oscillation and the Southern Annular Mode, on winter and spring phytoplankton biomass appear to be different among the three sampling stations, suggesting an important role of local-scale forcing than large-scale forcing on phytoplankton dynamics at each station. The inter-annual variability of seasonal bloom progression derived from considering all three stations together captured ecologically meaningful, seasonally co-occurring bloom patterns which were primarily constrained by water-column stability strength. Our findings highlight a coupled link between phytoplankton and physical and climate dynamics along the coastal WAP, which may improve our understanding of overall WAP food-web responses to climate change and variability.This article is part of the theme issue 'The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change'. © 2018 The Author(s).

Instrument comparison for Aerosolized Titanium Dioxide

NASA Astrophysics Data System (ADS)

Ranpara, Anand

Recent toxicological studies have shown that the surface area of ultrafine particles (UFP i.e., particles with diameters less than 0.1 micrometer) has a stronger correlation with adverse health effects than does mass of these particles. Ultrafine titanium dioxide (TiO2) particles are widely used in industry, and their use is associated with adverse health outcomes, such as micro vascular dysfunctions and pulmonary damages. The primary aim of this experimental study was to compare a variety of laboratory and industrial hygiene (IH) field study instruments all measuring the same aerosolized TiO2. The study also observed intra-instrument variability between measurements made by two apparently identical devices of the same type of instrument placed side-by-side. The types of instruments studied were (1) DustTrak(TM) DRX, (2) Personal Data RAMs(TM) (PDR), (3) GRIMM, (4) Diffusion charger (DC) and (5) Scanning Mobility Particle Sizer (SMPS). Two devices of each of the four IH field study instrument types were used to measure six levels of mass concentration of fine and ultrafine TiO2 aerosols in controlled chamber tests. Metrics evaluated included real-time mass, active surface area and number/geometric surface area distributions, and off-line gravimetric mass and morphology on filters. DustTrak(TM) DRXs and PDRs were used for mass concentration measurements. DCs were used for active surface area concentration measurements. GRIMMs were used for number concentration measurements. SMPS was used for inter-instrument comparisons of surface area and number concentrations. The results indicated that two apparently identical devices of each DRX and PDR were statistically not different with each other for all the trials of both the sizes of powder (p < 5%). Mean difference between mass concentrations measured by two DustTrak DRX devices was smaller than that measured by two PDR devices. DustTrak DRX measurements were closer to the reference method, gravimetric mass concentration

Estimating inter-annual variability in winter wheat sowing dates from satellite time series in Camargue, France

NASA Astrophysics Data System (ADS)

Manfron, Giacinto; Delmotte, Sylvestre; Busetto, Lorenzo; Hossard, Laure; Ranghetti, Luigi; Brivio, Pietro Alessandro; Boschetti, Mirco

2017-05-01

Crop simulation models are commonly used to forecast the performance of cropping systems under different hypotheses of change. Their use on a regional scale is generally constrained, however, by a lack of information on the spatial and temporal variability of environment-related input variables (e.g., soil) and agricultural practices (e.g., sowing dates) that influence crop yields. Satellite remote sensing data can shed light on such variability by providing timely information on crop dynamics and conditions over large areas. This paper proposes a method for analyzing time series of MODIS satellite data in order to estimate the inter-annual variability of winter wheat sowing dates. A rule-based method was developed to automatically identify a reliable sample of winter wheat field time series, and to infer the corresponding sowing dates. The method was designed for a case study in the Camargue region (France), where winter wheat is characterized by vernalization, as in other temperate regions. The detection criteria were chosen on the grounds of agronomic expertise and by analyzing high-confidence time-series vegetation index profiles for winter wheat. This automatic method identified the target crop on more than 56% (four-year average) of the cultivated areas, with low commission errors (11%). It also captured the seasonal variability in sowing dates with errors of ±8 and ±16 days in 46% and 66% of cases, respectively. Extending the analysis to the years 2002-2012 showed that sowing in the Camargue was usually done on or around November 1st (±4 days). Comparing inter-annual sowing date variability with the main local agro-climatic drivers showed that the type of preceding crop and the weather conditions during the summer season before the wheat sowing had a prominent role in influencing winter wheat sowing dates.

Effects of inter- and intra-observer variability on echocardiographic measurements in awake cats.

PubMed

Chetboul, V; Concordet, D; Pouchelon, J L; Athanassiadis, N; Muller, C; Benigni, L; Munari, A C; Lefebvre, H P

2003-08-01

The objective of this study was to determine intra- and inter-observer variability of echocardiographic measurements in awake cats. Four observers with different levels of experience in echocardiography performed 96 echocardiographic examinations in four cats on four different days over a 3-week period. The examinations were randomized and blinded. The maximum within-day and between-day CV values were 17.4 and 18.5% for inter-ventricular septal thickness in diastole, 18.7 and 22.6% for left ventricular free-wall thickness in diastole, 9.8 and 14.9% for left ventricular end-diastolic diameter, 20.8 and 15.2% for left ventricular end-systolic diameter, and 21.2 and 18.4% for left ventricular shortening fraction. The maximum within-day CV values were most often associated with the least competent observer (i.e. the graduate student) and, the minimum CV values with the most competent observer (i.e. the associate professor in cardiology). A significant interaction between cat and observer was also evidenced. Thus, the most competent observer could not be replaced by any of the other observers.

Inter-individual variability in the production of flavan-3-ol colonic metabolites: preliminary elucidation of urinary metabotypes.

PubMed

Mena, Pedro; Ludwig, Iziar A; Tomatis, Virginia B; Acharjee, Animesh; Calani, Luca; Rosi, Alice; Brighenti, Furio; Ray, Sumantra; Griffin, Julian L; Bluck, Les J; Del Rio, Daniele

2018-04-03

There is much information on the bioavailability of (poly)phenolic compounds following acute intake of various foods. However, there are only limited data on the effects of repeated and combined exposure to specific (poly)phenol food sources and the inter-individual variability in their bioavailability. This study evaluated the combined urinary excretion of (poly)phenols from green tea and coffee following daily consumption by healthy subjects in free-living conditions. The inter-individual variability in the production of phenolic metabolites was also investigated. Eleven participants consumed both tablets of green tea and green coffee bean extracts daily for 8 weeks and 24-h urine was collected on five different occasions. The urinary profile of phenolic metabolites and a set of multivariate statistical tests were used to investigate the putative existence of characteristic metabotypes in the production of flavan-3-ol microbial metabolites. (Poly)phenolic compounds in the green tea and green coffee bean extracts were absorbed and excreted after simultaneous consumption, with green tea resulting in more inter-individual variability in urinary excretion of phenolic metabolites. Three metabotypes in the production of flavan-3-ol microbial metabolites were tentatively defined, characterized by the excretion of different amounts of trihydroxyphenyl-γ-valerolactones, dihydroxyphenyl-γ-valerolactones, and hydroxyphenylpropionic acids. The selective production of microbiota-derived metabolites from flavan-3-ols and the putative existence of characteristic metabotypes in their production represent an important development in the study of the bioavailability of plant bioactives. These observations will contribute to better understand the health effects and individual differences associated with consumption of flavan-3-ols, arguably the main class of flavonoids in the human diet.

Non-technical skills evaluation in the critical care air ambulance environment: introduction of an adapted rating instrument--an observational study.

PubMed

Myers, Julia A; Powell, David M C; Psirides, Alex; Hathaway, Karyn; Aldington, Sarah; Haney, Michael F

2016-03-08

In the isolated and dynamic health-care setting of critical care air ambulance transport, the quality of clinical care is strongly influenced by non-technical skills such as anticipating, recognising and understanding, decision making, and teamwork. However there are no published reports identifying or applying a non-technical skills framework specific to an intensive care air ambulance setting. The objective of this study was to adapt and evaluate a non-technical skills rating framework for the air ambulance clinical environment. In the first phase of the project the anaesthetists' non-technical skills (ANTS) framework was adapted to the air ambulance setting, using data collected directly from clinician groups, published literature, and field observation. In the second phase experienced and inexperienced inter-hospital transport clinicians completed a simulated critical care air transport scenario, and their non-technical skills performance was independently rated by two blinded assessors. Observed and self-rated general clinical performance ratings were also collected. Rank-based statistical tests were used to examine differences in the performance of experienced and inexperienced clinicians, and relationships between different assessment approaches and assessors. The framework developed during phase one was referred to as an aeromedical non-technical skills framework, or AeroNOTS. During phase two 16 physicians from speciality training programmes in intensive care, emergency medicine and anaesthesia took part in the clinical simulation study. Clinicians with inter-hospital transport experience performed more highly than those without experience, according to both AeroNOTS non-technical skills ratings (p = 0.001) and general performance ratings (p = 0.003). Self-ratings did not distinguish experienced from inexperienced transport clinicians (p = 0.32) and were not strongly associated with either observed general performance (r(s) = 0.4, p = 0

Inter- and Intra-individual Variability in Response to Transcranial Direct Current Stimulation (tDCS) at Varying Current Intensities.

PubMed

Chew, Taariq; Ho, Kerrie-Anne; Loo, Colleen K

2015-01-01

Translation of transcranial direct current stimulation (tDCS) from research to clinical practice is hindered by a lack of consensus on optimal stimulation parameters, significant inter-individual variability in response, and in sufficient intra-individual reliability data. Inter-individual differences in response to anodal tDCS at a range of current intensities were explored. Intra-individual reliability in response to anodal tDCS across two identical sessions was also investigated. Twenty-nine subjects participated in a crossover study. Anodal-tDCS using four different current intensities (0.2, 0.5, 1 and 2 mA), with an anode size of 16 cm2, was tested. The 0.5 mA condition was repeated to assess intra-individual variability. TMS was used to elicit 40 motor-evoked potentials (MEPs) before 10 min of tDCS, and 20 MEPs at four time-points over 30 min following tDCS. ANOVA revealed no main effect of TIME for all conditions except the first 0.5 mA condition, and no differences in response between the four current intensities. Cluster analysis identified two clusters for the 0.2 and 2 mA conditions only. Frequency distributions based on individual subject responses (excitatory, inhibitory or no response) to each condition indicate possible differential responses between individuals to different current intensities. Test-retest reliability was negligible (ICC(2,1) = -0.50). Significant inter-individual variability in response to tDCS across a range of current intensities was found. 2 mA and 0.2 mA tDCS were most effective at inducing a distinct response. Significant intra-individual variability in response to tDCS was also found. This has implications for interpreting results of single-session tDCS experiments. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

Inter-annual variability and spatial coherence of net primary productivity across a western Oregon Cascades landscape

Treesearch

Travis J. Woolley; Mark E. Harmon; Kari B. O’Connell

2015-01-01

Inter-annual variability (IAV) of forest Net Primary Productivity (NPP) is a function of both extrinsic (e.g., climate) and intrinsic (e.g., stand dynamics) drivers. As estimates of NPP in forests are scaled from trees to stands to the landscape, an understanding of the relative effects of these factors on spatial and temporal behavior of NPP is important. Although a...

Climate Variability and Inter-Provincial Migration in South America, 1970-2011

PubMed Central

Thiede, Brian; Gray, Clark; Mueller, Valerie

2016-01-01

We examine the effect of climate variability on human migration in South America. Our analyses draw on over 21 million observations of adults aged 15-40 from 25 censuses conducted in eight South American countries. Addressing limitations associated with methodological diversity among prior studies, we apply a common analytic approach and uniform definitions of migration and climate across all countries. We estimate the effects of climate variability on migration overall and also investigate heterogeneity across sex, age, and socioeconomic groups, across countries, and across historical climate conditions. We also disaggregate migration by the rural/urban status of destination. We find that exposure to monthly temperature shocks has the most consistent effects on migration relative to monthly rainfall shocks and gradual changes in climate over multi-year periods. We also find evidence of heterogeneity across demographic groups and countries. Analyses that disaggregate migration by the rural/urban status of destination suggest that much of the climate-related inter-province migration is directed toward urban areas. Overall, our results underscore the complexity of environment-migration linkages and challenge simplistic narratives that envision a linear and monolithic migratory response to changing climates. PMID:28413264

Climate Variability and Inter-Provincial Migration in South America, 1970-2011.

PubMed

Thiede, Brian; Gray, Clark; Mueller, Valerie

2016-11-01

We examine the effect of climate variability on human migration in South America. Our analyses draw on over 21 million observations of adults aged 15-40 from 25 censuses conducted in eight South American countries. Addressing limitations associated with methodological diversity among prior studies, we apply a common analytic approach and uniform definitions of migration and climate across all countries. We estimate the effects of climate variability on migration overall and also investigate heterogeneity across sex, age, and socioeconomic groups, across countries, and across historical climate conditions. We also disaggregate migration by the rural/urban status of destination. We find that exposure to monthly temperature shocks has the most consistent effects on migration relative to monthly rainfall shocks and gradual changes in climate over multi-year periods. We also find evidence of heterogeneity across demographic groups and countries. Analyses that disaggregate migration by the rural/urban status of destination suggest that much of the climate-related inter-province migration is directed toward urban areas. Overall, our results underscore the complexity of environment-migration linkages and challenge simplistic narratives that envision a linear and monolithic migratory response to changing climates.

How Plantar Exteroceptive Efficiency Modulates Postural and Oculomotor Control: Inter-Individual Variability.

PubMed

Foisy, Arnaud; Kapoula, Zoï

2016-01-01

In a previous experiment, we showed that among young and healthy subjects, thin plantar inserts improve postural control and modify vergence amplitudes. In this experiment, however, significant inter-individual variability was observed. We hypothesize that its origin could be attributed to a different reliance upon feet cutaneous afferents. In order to test this hypothesis, we re-analyzed the data relative to 31 young (age 25.7 ± 3.8) and healthy subjects who participated in the first experiment after having classified them into two groups depending on their Plantar Quotient (PQ = Surface area of CoPfoam/Surface area of CoPfirm ground × 100). Foam decreases the information arising from the feet, normally resulting in a PQ > 100. Hence, the PQ provides information on the weight of plantar cutaneous afferents used in postural control. Twelve people were Plantar-Independent Subjects, as indicated by a PQ < 100. These individuals did not behave like the Normal Plantar Quotient Subjects: they were almost insensitive to the plantar stimulations in terms of postural control and totally insensitive in terms of oculomotor control. We conclude that the inter-individual variability observed in our first experiment is explained by the subjects' degree of plantar reliance. We propose that plantar independence is a dysfunctional situation revealing inefficiency in plantar cutaneous afferents. The latter could be due to a latent somatosensory dysfunction generating a noise which prevents the CNS from correctly processing and using feet somatosensory afferents both for balance and vergence control: Plantar Irritating Stimulus. Considering the non-noxious nature and prevalence of this phenomenon, these results can be of great interest to researchers and clinicians who attempt to trigger postural or oculomotor responses through mechanical stimulation of the foot sole.

Impacts of correcting the inter-variable correlation of climate model outputs on hydrological modeling

NASA Astrophysics Data System (ADS)

Chen, Jie; Li, Chao; Brissette, François P.; Chen, Hua; Wang, Mingna; Essou, Gilles R. C.

2018-05-01

Bias correction is usually implemented prior to using climate model outputs for impact studies. However, bias correction methods that are commonly used treat climate variables independently and often ignore inter-variable dependencies. The effects of ignoring such dependencies on impact studies need to be investigated. This study aims to assess the impacts of correcting the inter-variable correlation of climate model outputs on hydrological modeling. To this end, a joint bias correction (JBC) method which corrects the joint distribution of two variables as a whole is compared with an independent bias correction (IBC) method; this is considered in terms of correcting simulations of precipitation and temperature from 26 climate models for hydrological modeling over 12 watersheds located in various climate regimes. The results show that the simulated precipitation and temperature are considerably biased not only in the individual distributions, but also in their correlations, which in turn result in biased hydrological simulations. In addition to reducing the biases of the individual characteristics of precipitation and temperature, the JBC method can also reduce the bias in precipitation-temperature (P-T) correlations. In terms of hydrological modeling, the JBC method performs significantly better than the IBC method for 11 out of the 12 watersheds over the calibration period. For the validation period, the advantages of the JBC method are greatly reduced as the performance becomes dependent on the watershed, GCM and hydrological metric considered. For arid/tropical and snowfall-rainfall-mixed watersheds, JBC performs better than IBC. For snowfall- or rainfall-dominated watersheds, however, the two methods behave similarly, with IBC performing somewhat better than JBC. Overall, the results emphasize the advantages of correcting the P-T correlation when using climate model-simulated precipitation and temperature to assess the impact of climate change on watershed

[Instrumental, directive, and affective communication in hospital leaflets].

PubMed

Vasconcellos-Silva, Paulo Roberto; Uribe Rivera, Francisco Javier; Castiel, Luis David

2003-01-01

This study focuses on the typical semantic systems extracted from hospital staff communicative resources which attempt to validate information as an "object" to be transferred to patients. We describe the models of textual communication in 58 patient information leaflets from five hospital units in Brazil, gathered from 1996 to 2002. Three categories were identified, based on the theory of speech acts (Austin, Searle, and Habermas): 1) cognitive-instrumental utterances: descriptions by means of technical terms validated by self-referred, incomplete, or inaccessible argumentation, with an implicit educational function; 2) technical-directive utterances: self-referred (to the context of the source domains), with a shifting of everyday acts to a technical terrain with a disciplinary function and impersonal features; and 3) expressive modulations: need for inter-subjective connections to strengthen bonds of trust and a tendency to use childish arguments. We conclude that the three categories displayed: fragmentary sources; assumption of univocal messages and invariable use of information (idealized motivations and interests, apart from individualized perspectives); and assumption of universal interests as generators of knowledge.

Missing data and technical variability in single-cell RNA-sequencing experiments.

PubMed

Hicks, Stephanie C; Townes, F William; Teng, Mingxiang; Irizarry, Rafael A

2017-11-06

Until recently, high-throughput gene expression technology, such as RNA-Sequencing (RNA-seq) required hundreds of thousands of cells to produce reliable measurements. Recent technical advances permit genome-wide gene expression measurement at the single-cell level. Single-cell RNA-Seq (scRNA-seq) is the most widely used and numerous publications are based on data produced with this technology. However, RNA-seq and scRNA-seq data are markedly different. In particular, unlike RNA-seq, the majority of reported expression levels in scRNA-seq are zeros, which could be either biologically-driven, genes not expressing RNA at the time of measurement, or technically-driven, genes expressing RNA, but not at a sufficient level to be detected by sequencing technology. Another difference is that the proportion of genes reporting the expression level to be zero varies substantially across single cells compared to RNA-seq samples. However, it remains unclear to what extent this cell-to-cell variation is being driven by technical rather than biological variation. Furthermore, while systematic errors, including batch effects, have been widely reported as a major challenge in high-throughput technologies, these issues have received minimal attention in published studies based on scRNA-seq technology. Here, we use an assessment experiment to examine data from published studies and demonstrate that systematic errors can explain a substantial percentage of observed cell-to-cell expression variability. Specifically, we present evidence that some of these reported zeros are driven by technical variation by demonstrating that scRNA-seq produces more zeros than expected and that this bias is greater for lower expressed genes. In addition, this missing data problem is exacerbated by the fact that this technical variation varies cell-to-cell. Then, we show how this technical cell-to-cell variability can be confused with novel biological results. Finally, we demonstrate and discuss how batch

Site-specific 13C content by quantitative isotopic 13C nuclear magnetic resonance spectrometry: a pilot inter-laboratory study.

PubMed

Chaintreau, Alain; Fieber, Wolfgang; Sommer, Horst; Gilbert, Alexis; Yamada, Keita; Yoshida, Naohiro; Pagelot, Alain; Moskau, Detlef; Moreno, Aitor; Schleucher, Jürgen; Reniero, Fabiano; Holland, Margaret; Guillou, Claude; Silvestre, Virginie; Akoka, Serge; Remaud, Gérald S

2013-07-25

Isotopic (13)C NMR spectrometry, which is able to measure intra-molecular (13)C composition, is of emerging demand because of the new information provided by the (13)C site-specific content of a given molecule. A systematic evaluation of instrumental behaviour is of importance to envisage isotopic (13)C NMR as a routine tool. This paper describes the first collaborative study of intra-molecular (13)C composition by NMR. The main goals of the ring test were to establish intra- and inter-variability of the spectrometer response. Eight instruments with different configuration were retained for the exercise on the basis of a qualification test. Reproducibility at the natural abundance of isotopic (13)C NMR was then assessed on vanillin from three different origins associated with specific δ (13)Ci profiles. The standard deviation was, on average, between 0.9 and 1.2‰ for intra-variability. The highest standard deviation for inter-variability was 2.1‰. This is significantly higher than the internal precision but could be considered good in respect of a first ring test on a new analytical method. The standard deviation of δ (13)Ci in vanillin was not homogeneous over the eight carbons, with no trend either for the carbon position or for the configuration of the spectrometer. However, since the repeatability for each instrument was satisfactory, correction factors for each carbon in vanillin could be calculated to harmonize the results. Copyright © 2013 Elsevier B.V. All rights reserved.

Longitudinal Surveys of Australian Youth (LSAY): 1995 Cohort Derived Variables. Technical Report 69

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2012

2012-01-01

This technical report details the derived variables developed for users of the Longitudinal Surveys of Australian Youth (LSAY) data. The derived variables fall into the categories education, employment and social, and help to simplify the complexity of the LSAY data by providing useful indicators for analysis. To help LSAY data users understand…

Network Mendelian randomization: using genetic variants as instrumental variables to investigate mediation in causal pathways

PubMed Central

Burgess, Stephen; Daniel, Rhian M; Butterworth, Adam S; Thompson, Simon G

2015-01-01

Background: Mendelian randomization uses genetic variants, assumed to be instrumental variables for a particular exposure, to estimate the causal effect of that exposure on an outcome. If the instrumental variable criteria are satisfied, the resulting estimator is consistent even in the presence of unmeasured confounding and reverse causation. Methods: We extend the Mendelian randomization paradigm to investigate more complex networks of relationships between variables, in particular where some of the effect of an exposure on the outcome may operate through an intermediate variable (a mediator). If instrumental variables for the exposure and mediator are available, direct and indirect effects of the exposure on the outcome can be estimated, for example using either a regression-based method or structural equation models. The direction of effect between the exposure and a possible mediator can also be assessed. Methods are illustrated in an applied example considering causal relationships between body mass index, C-reactive protein and uric acid. Results: These estimators are consistent in the presence of unmeasured confounding if, in addition to the instrumental variable assumptions, the effects of both the exposure on the mediator and the mediator on the outcome are homogeneous across individuals and linear without interactions. Nevertheless, a simulation study demonstrates that even considerable heterogeneity in these effects does not lead to bias in the estimates. Conclusions: These methods can be used to estimate direct and indirect causal effects in a mediation setting, and have potential for the investigation of more complex networks between multiple interrelated exposures and disease outcomes. PMID:25150977

Genetic instrumental variable regression: Explaining socioeconomic and health outcomes in nonexperimental data

PubMed Central

DiPrete, Thomas A.; Burik, Casper A. P.; Koellinger, Philipp D.

2018-01-01

Identifying causal effects in nonexperimental data is an enduring challenge. One proposed solution that recently gained popularity is the idea to use genes as instrumental variables [i.e., Mendelian randomization (MR)]. However, this approach is problematic because many variables of interest are genetically correlated, which implies the possibility that many genes could affect both the exposure and the outcome directly or via unobserved confounding factors. Thus, pleiotropic effects of genes are themselves a source of bias in nonexperimental data that would also undermine the ability of MR to correct for endogeneity bias from nongenetic sources. Here, we propose an alternative approach, genetic instrumental variable (GIV) regression, that provides estimates for the effect of an exposure on an outcome in the presence of pleiotropy. As a valuable byproduct, GIV regression also provides accurate estimates of the chip heritability of the outcome variable. GIV regression uses polygenic scores (PGSs) for the outcome of interest which can be constructed from genome-wide association study (GWAS) results. By splitting the GWAS sample for the outcome into nonoverlapping subsamples, we obtain multiple indicators of the outcome PGSs that can be used as instruments for each other and, in combination with other methods such as sibling fixed effects, can address endogeneity bias from both pleiotropy and the environment. In two empirical applications, we demonstrate that our approach produces reasonable estimates of the chip heritability of educational attainment (EA) and show that standard regression and MR provide upwardly biased estimates of the effect of body height on EA. PMID:29686100

Genetic instrumental variable regression: Explaining socioeconomic and health outcomes in nonexperimental data.

PubMed

DiPrete, Thomas A; Burik, Casper A P; Koellinger, Philipp D

2018-05-29

Identifying causal effects in nonexperimental data is an enduring challenge. One proposed solution that recently gained popularity is the idea to use genes as instrumental variables [i.e., Mendelian randomization (MR)]. However, this approach is problematic because many variables of interest are genetically correlated, which implies the possibility that many genes could affect both the exposure and the outcome directly or via unobserved confounding factors. Thus, pleiotropic effects of genes are themselves a source of bias in nonexperimental data that would also undermine the ability of MR to correct for endogeneity bias from nongenetic sources. Here, we propose an alternative approach, genetic instrumental variable (GIV) regression, that provides estimates for the effect of an exposure on an outcome in the presence of pleiotropy. As a valuable byproduct, GIV regression also provides accurate estimates of the chip heritability of the outcome variable. GIV regression uses polygenic scores (PGSs) for the outcome of interest which can be constructed from genome-wide association study (GWAS) results. By splitting the GWAS sample for the outcome into nonoverlapping subsamples, we obtain multiple indicators of the outcome PGSs that can be used as instruments for each other and, in combination with other methods such as sibling fixed effects, can address endogeneity bias from both pleiotropy and the environment. In two empirical applications, we demonstrate that our approach produces reasonable estimates of the chip heritability of educational attainment (EA) and show that standard regression and MR provide upwardly biased estimates of the effect of body height on EA. Copyright © 2018 the Author(s). Published by PNAS.

Trend Change Detection in NDVI Time Series: Effects of Inter-Annual Variability and Methodology

NASA Technical Reports Server (NTRS)

Forkel, Matthias; Carvalhais, Nuno; Verbesselt, Jan; Mahecha, Miguel D.; Neigh, Christopher S.R.; Reichstein, Markus

2013-01-01

Changing trends in ecosystem productivity can be quantified using satellite observations of Normalized Difference Vegetation Index (NDVI). However, the estimation of trends from NDVI time series differs substantially depending on analyzed satellite dataset, the corresponding spatiotemporal resolution, and the applied statistical method. Here we compare the performance of a wide range of trend estimation methods and demonstrate that performance decreases with increasing inter-annual variability in the NDVI time series. Trend slope estimates based on annual aggregated time series or based on a seasonal-trend model show better performances than methods that remove the seasonal cycle of the time series. A breakpoint detection analysis reveals that an overestimation of breakpoints in NDVI trends can result in wrong or even opposite trend estimates. Based on our results, we give practical recommendations for the application of trend methods on long-term NDVI time series. Particularly, we apply and compare different methods on NDVI time series in Alaska, where both greening and browning trends have been previously observed. Here, the multi-method uncertainty of NDVI trends is quantified through the application of the different trend estimation methods. Our results indicate that greening NDVI trends in Alaska are more spatially and temporally prevalent than browning trends. We also show that detected breakpoints in NDVI trends tend to coincide with large fires. Overall, our analyses demonstrate that seasonal trend methods need to be improved against inter-annual variability to quantify changing trends in ecosystem productivity with higher accuracy.

The individualistic fallacy, ecological studies and instrumental variables: a causal interpretation.

PubMed

Loney, Tom; Nagelkerke, Nico J

2014-01-01

The validity of ecological studies in epidemiology for inferring causal relationships has been widely challenged as observed associations could be biased by the Ecological Fallacy. We reconsider the important design components of ecological studies, and discuss the conditions that may lead to spurious associations. Ecological associations are useful and valid when the ecological exposures can be interpreted as Instrumental Variables. A suitable example may be a time series analysis of environmental pollution (e.g. particulate matter with an aerodynamic diameter of <10 micrometres; PM10) and health outcomes (e.g. hospital admissions for acute myocardial infarction) as environmental pollution levels are a cause of individual exposure levels and not just an aggregate measurement. Ecological exposures may also be employed in situations (perhaps rare) where individual exposures are known but their associations with health outcomes are confounded by unknown or unquantifiable factors. Ecological associations have a notorious reputation in epidemiology and individualistic associations are considered superior to ecological associations because of the "ecological fallacy". We have argued that this is incorrect in situations in which ecological or aggregate exposures can serve as an instrumental variable and associations between individual exposure and outcome are likely to be confounded by unmeasured variables.

The Effect of Birth Weight on Academic Performance: Instrumental Variable Analysis.

PubMed

Lin, Shi Lin; Leung, Gabriel Matthew; Schooling, C Mary

2017-05-01

Observationally, lower birth weight is usually associated with poorer academic performance; whether this association is causal or the result of confounding is unknown. To investigate this question, we obtained an effect estimate, which can have a causal interpretation under specific assumptions, of birth weight on educational attainment using instrumental variable analysis based on single nucleotide polymorphisms determining birth weight combined with results from the Social Science Genetic Association Consortium study of 126,559 Caucasians. We similarly obtained an estimate of the effect of birth weight on academic performance in 4,067 adolescents from Hong Kong's (Chinese) Children of 1997 birth cohort (1997-2016), using twin status as an instrumental variable. Birth weight was not associated with years of schooling (per 100-g increase in birth weight, -0.006 years, 95% confidence interval (CI): -0.02, 0.01) or college completion (odds ratio = 1.00, 95% CI: 0.96, 1.03). Birth weight was also unrelated to academic performance in adolescents (per 100-g increase in birth weight, -0.004 grade, 95% CI: -0.04, 0.04) using instrumental variable analysis, although conventional regression gave a small positive association (0.02 higher grade, 95% CI: 0.01, 0.03). Observed associations of birth weight with academic performance may not be causal, suggesting that interventions should focus on the contextual factors generating this correlation. © The Author 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Trends and Controls of inter-annual Variability in the Carbon Budget of Terrestrial Ecosystems

NASA Astrophysics Data System (ADS)

Cescatti, A.; Marcolla, B.

2014-12-01

The climate sensitivity of the terrestrial carbon budget will substantially affect the sign and strength of the land-climate feedbacks and the future climate trajectories. Current trends in the inter-annual variability of terrestrial carbon fluxes (IAV) may contribute to clarify the relative role of physical and biological controls of ecosystem responses to climate change. For this purpose we investigated how recent climate variability has impacted the carbon fluxes at long-term FLUXNET sites. Using a novel method, the IAV has been factored out in climate induced variability (physical control), variability due to changes in ecosystem functioning (biological control) and the interaction of the two terms. The relative control of the main climatic drivers (temperature, water availability) on the physical and biological sources of IAV has been investigated using both site level fluxes and global gridded products generated from the up-scaling of flux data. Results of this analysis highlight the fundamental role of precipitation trends on the pattern of IAV in the last 30 years. Our findings on the spatial/temporal trends of IAV have been finally confirmed using the signal derived from the global network of atmospheric CO2 concentrations measurements.

Designing low-carbon power systems for Great Britain in 2050 that are robust to the spatiotemporal and inter-annual variability of weather

NASA Astrophysics Data System (ADS)

Zeyringer, Marianne; Price, James; Fais, Birgit; Li, Pei-Hao; Sharp, Ed

2018-05-01

The design of cost-effective power systems with high shares of variable renewable energy (VRE) technologies requires a modelling approach that simultaneously represents the whole energy system combined with the spatiotemporal and inter-annual variability of VRE. Here, we soft-link a long-term energy system model, which explores new energy system configurations from years to decades, with a high spatial and temporal resolution power system model that captures VRE variability from hours to years. Applying this methodology to Great Britain for 2050, we find that VRE-focused power system design is highly sensitive to the inter-annual variability of weather and that planning based on a single year can lead to operational inadequacy and failure to meet long-term decarbonization objectives. However, some insights do emerge that are relatively stable to weather-year. Reinforcement of the transmission system consistently leads to a decrease in system costs while electricity storage and flexible generation, needed to integrate VRE into the system, are generally deployed close to demand centres.

Intra- and Inter-observer Variability of Measurements of the Laxity Index on Stress Radiographs Performed with the Vezzoni-Modified Badertscher Hip Distension Device.

PubMed

Bertal, Mileva; Vezzoni, Aldo; Houdellier, Blandine; Bogaerts, Evelien; Stock, Emmelie; Polis, Ingeborgh; Deforce, Dieter; Saunders, Jimmy H; Broeckx, Bart J G

2018-06-02

 To describe and evaluate the accuracy, intra- and inter-observer variability of the laxity index (LI), used to quantify hip laxity on stress radiographs obtained with the Vezzoni-modified Badertscher distension device (VMBDD).  Stress radiographs of 10 dogs obtained with the VMBDD were measured three times by an experienced observer. Six participants with different backgrounds (two ECVDI residents, two PhD students, two veterinary assistants) followed a short presentation and performed subsequently the measurements four times in two separate sessions. The effect of self-learning, feedback and specialization on the accuracy of the measurements was assessed.  While the intra- and inter-observer variability were in agreement with other studies, the results of the experienced observer indicated that the variability can be very low. Neither feedback nor self-learning improved the results. A high degree of experience in radiographic assessment was not necessary to perform the measurements correctly.  As the LI measurements were acceptable after a short presentation, they support the use of VMBDD for a complete and correct in-house evaluation of the hip joint by trained clinicians. However, we propose that, in the context of screening, measurements should be performed by a limited number of experienced examiners, to limit the impact of the inter-observer variability. Schattauer GmbH Stuttgart.

Measurement of inter- and intra-annual variability of landscape fire activity at a continental scale: The Australian case

Treesearch

Grant J. Williamson; Lynda D. Prior; Matt Jolly; Mark A. Cochrane; Brett P. Murphy; David M. J. S. Bowman

2016-01-01

Climate dynamics at diurnal, seasonal and inter-annual scales shape global fire activity, although difficulties of assembling reliable fire and meteorological data with sufficient spatio-temporal resolution have frustrated quantification of this variability. Using Australia as a case study, we combine data from 4760 meteorological stations with 12 years of satellite-...

ENSO Related Inter-Annual Lightning Variability from the Full TRMM LIS Lightning Climatology

NASA Technical Reports Server (NTRS)

Clark, Austin; Cecil, Daniel

2018-01-01

The El Nino/Southern Oscillation (ENSO) contributes to inter-annual variability of lightning production more than any other atmospheric oscillation. This study further investigated how ENSO phase affects lightning production in the tropics and subtropics using the Tropical Rainfall Measuring Mission (TRMM) Lightning Imaging Sensor (LIS). Lightning data were averaged into mean annual warm, cold, and neutral 'years' for analysis of the different phases and compared to model reanalysis data. An examination of the regional sensitivities and preliminary analysis of three locations was conducted using model reanalysis data to determine the leading convective mechanisms in these areas and how they might respond to the ENSO phases

A review of interventions to reduce inter-observer variability in volume delineation in radiation oncology.

PubMed

Vinod, Shalini K; Min, Myo; Jameson, Michael G; Holloway, Lois C

2016-06-01

Inter-observer variability (IOV) in target volume and organ-at-risk (OAR) delineation is a source of potential error in radiation therapy treatment. The aims of this study were to identify interventions shown to reduce IOV in volume delineation. Medline and Pubmed databases were queried for relevant articles using various keywords to identify articles which evaluated IOV in target or OAR delineation for multiple (>2) observers. The search was limited to English language articles and to those published from 1 January 2000 to 31 December 2014. Reference lists of identified articles were scrutinised to identify relevant studies. Studies were included if they reported IOV in contouring before and after an intervention including the use of additional or alternative imaging. Fifty-six studies were identified. These were grouped into evaluation of guidelines (n = 9), teaching (n = 9), provision of an autocontour (n = 7) and the impact of imaging (n = 31) on IOV. Guidelines significantly reduced IOV in 7/9 studies. Teaching interventions reduced IOV in 8/9 studies, statistically significant in 4. The provision of an autocontour improved consistency of contouring in 6/7 studies, statistically significant in 5. The effect of additional imaging on IOV was variable. Pre-operative CT was useful in reducing IOV in contouring breast and liver cancers, PET scans in lung cancer, rectal cancer and lymphoma and MRI scans in OARs in head and neck cancers. Inter-observer variability in volume delineation can be reduced with the use of guidelines, provision of autocontours and teaching. The use of multimodality imaging is useful in certain tumour sites. © 2016 The Royal Australian and New Zealand College of Radiologists.

Inter-Annual Variability in Stream Water Temperature, Microclimate and Heat Exchanges: a Comparison of Forest and Moorland Environments

NASA Astrophysics Data System (ADS)

Garner, G.; Hannah, D. M.; Malcolm, I.; Sadler, J. P.

2012-12-01

Riparian forest is recognised as important for moderating stream temperature variability and has the potential to mitigate thermal extremes in a changing climate. Previous research on the heat exchanges controlling water column temperature has often been short-term or seasonally-constrained, with the few multi-year studies limited to a maximum of two years. This study advances previous work by providing a longer-term perspective which allows assessment of inter-annual variability in stream temperature, microclimate and heat exchange dynamics between a semi-natural woodland and a moorland (no trees) reach of the Girnock Burn, a tributary of the Scottish Dee. Automatic weather stations collected 15-minute data over seven consecutive years, which to our knowledge is a unique data set in providing the longest term perspective to date on stream temperature, microclimate and heat exchange processes. Results for spring-summer indicate that the presence of a riparian canopy has a consistent effect between years in reducing the magnitude and variability of mean daily water column temperature and daily net energy totals. Differences in the magnitude and variability in net energy fluxes between the study reaches were driven primarily by fluctuations in net radiation and latent heat fluxes in response to between- and within-year variability in growth of the riparian forest canopy at the forest and prevailing weather conditions at both the forest and moorland. This research provides new insights on the inter-annual variability of stream energy exchanges for moorland and forested reaches under a wide range of climatological and hydrological conditions. The findings therefore provide a more robust process basis for modelling the impact of changes in forest practice and climate change on river thermal dynamics.

Gonioscopy in the dog: inter-examiner variability and the search for a grading scheme.

PubMed

Oliver, J A C; Cottrell, B C; Newton, J R; Mellersh, C S

2017-11-01

To investigate inter-examiner variability in gonioscopic evaluation of pectinate ligament abnormality in dogs and to assess level of inter-examiner agreement for four different gonioscopy grading schemes. Two examiners performed gonioscopy in 98 eyes of 49 Welsh springer spaniel dogs and estimated the percentage circumference of iridocorneal angle affected by pectinate ligament abnormality to the nearest 5%. Percentage scores assigned to each eye by the two examiners were compared. Inter-examiner agreement was assessed following assignment of the percentage scores to each of four grading schemes by Cohen's kappa statistic. There was a strong positive correlation between the results of the two examiners (R=0·91). In general, Examiner 1 scored individual eyes higher than Examiner 2, especially for eyes in which both examiners diagnosed pectinate ligament abnormality. A "good" level of agreement could only be achieved with a gonioscopy grading scheme of no more than three categories and with a relatively large intermediate bandwidth (κ=0·68). A three-tiered grading scheme might represent an improvement on hereditary eye disease schemes which simply classify dogs to be either "affected" or "unaffected" for pectinate ligament abnormality. However, the large intermediate bandwidth of this scheme would only allow for the additional detection of those dogs with marked progression of pectinate ligament abnormality which would be considered most at risk of primary closed-angle glaucoma. © 2017 British Small Animal Veterinary Association.

Genetic Instrumental Variable Studies of Effects of Prenatal Risk Factors

PubMed Central

von Hinke Kessler Scholder, Stephanie

2013-01-01

Identifying the effects of maternal risk factors during pregnancy on infant and child health is an area of tremendous research interest. However, of interest to policy makers is unraveling the causal effects of prenatal risk factors, not their associations with child health, which may be confounded by several unobserved factors. In this paper, we evaluate the utility of genetic variants in three genes that have unequivocal evidence of being related to three major risk factors – CHRNA3 for smoking, ADH1B for alcohol use, and FTO for obesity – as instrumental variables for identifying the causal effects of such factors during pregnancy. Using two independent datasets, we find that these variants are overall predictive of the risk factors and are not systematically related to observed confounders, suggesting that they may be useful instruments. We also find some suggestive evidence that genetic effects are stronger during than before pregnancy. We provide an empirical example illustrating the use of these genetic variants as instruments to evaluate the effects of risk factors on birth weight. Finally, we offer suggestions for researchers contemplating the use of these variants as instruments. PMID:23701534

Critical discussion of evaluation parameters for inter-observer variability in target definition for radiation therapy.

PubMed

Fotina, I; Lütgendorf-Caucig, C; Stock, M; Pötter, R; Georg, D

2012-02-01

Inter-observer studies represent a valid method for the evaluation of target definition uncertainties and contouring guidelines. However, data from the literature do not yet give clear guidelines for reporting contouring variability. Thus, the purpose of this work was to compare and discuss various methods to determine variability on the basis of clinical cases and a literature review. In this study, 7 prostate and 8 lung cases were contoured on CT images by 8 experienced observers. Analysis of variability included descriptive statistics, calculation of overlap measures, and statistical measures of agreement. Cross tables with ratios and correlations were established for overlap parameters. It was shown that the minimal set of parameters to be reported should include at least one of three volume overlap measures (i.e., generalized conformity index, Jaccard coefficient, or conformation number). High correlation between these parameters and scatter of the results was observed. A combination of descriptive statistics, overlap measure, and statistical measure of agreement or reliability analysis is required to fully report the interrater variability in delineation.

Statistical Analysis for Multisite Trials Using Instrumental Variables with Random Coefficients

ERIC Educational Resources Information Center

Raudenbush, Stephen W.; Reardon, Sean F.; Nomi, Takako

2012-01-01

Multisite trials can clarify the average impact of a new program and the heterogeneity of impacts across sites. Unfortunately, in many applications, compliance with treatment assignment is imperfect. For these applications, we propose an instrumental variable (IV) model with person-specific and site-specific random coefficients. Site-specific IV…

Bias and Bias Correction in Multisite Instrumental Variables Analysis of Heterogeneous Mediator Effects

ERIC Educational Resources Information Center

Reardon, Sean F.; Unlu, Fatih; Zhu, Pei; Bloom, Howard S.

2014-01-01

We explore the use of instrumental variables (IV) analysis with a multisite randomized trial to estimate the effect of a mediating variable on an outcome in cases where it can be assumed that the observed mediator is the only mechanism linking treatment assignment to outcomes, an assumption known in the IV literature as the exclusion restriction.…

Inter-laboratory analysis of selected genetically modified plant reference materials with digital PCR.

PubMed

Dobnik, David; Demšar, Tina; Huber, Ingrid; Gerdes, Lars; Broeders, Sylvia; Roosens, Nancy; Debode, Frederic; Berben, Gilbert; Žel, Jana

2018-01-01

Digital PCR (dPCR), as a new technology in the field of genetically modified (GM) organism (GMO) testing, enables determination of absolute target copy numbers. The purpose of our study was to test the transferability of methods designed for quantitative PCR (qPCR) to dPCR and to carry out an inter-laboratory comparison of the performance of two different dPCR platforms when determining the absolute GM copy numbers and GM copy number ratio in reference materials certified for GM content in mass fraction. Overall results in terms of measured GM% were within acceptable variation limits for both tested dPCR systems. However, the determined absolute copy numbers for individual genes or events showed higher variability between laboratories in one third of the cases, most possibly due to variability in the technical work, droplet size variability, and analysis of the raw data. GMO quantification with dPCR and qPCR was comparable. As methods originally designed for qPCR performed well in dPCR systems, already validated qPCR assays can most generally be used for dPCR technology with the purpose of GMO detection. Graphical abstract The output of three different PCR-based platforms was assessed in an inter-laboratory comparison.

Inter-Population Variability of Endosymbiont Densities in the Asian Citrus Psyllid (Diaphorina citri Kuwayama).

PubMed

Chu, Chia-Ching; Gill, Torrence A; Hoffmann, Mark; Pelz-Stelinski, Kirsten S

2016-05-01

The Asian citrus psyllid (Diaphorina citri Kuwayama) is an insect pest capable of transmitting Candidatus Liberibacter asiaticus (CLas), the causal agent of citrus greening in North America. D. citri also harbors three endosymbionts, Wolbachia, Candidatus Carsonella ruddii, and Candidatus Profftella armatura, which may influence D. citri physiology and fitness. Although genomic researches on these bacteria have been conducted, much remains unclear regarding their ecology and inter-population variability in D. citri. The present work examined the densities of each endosymbiont in adult D. citri sampled from different populations using quantitative PCR. Under field conditions, the densities of all three endosymbionts positively correlated with each other, and they are associated with D. citri gender and locality. In addition, the infection density of CLas also varied across populations. Although an analysis pooling D. citri from different populations showed that CLas-infected individuals tended to have lower endosymbiont densities compared to uninfected individuals, the difference was not significant when the population was included as a factor in the analysis, suggesting that other population-specific factors may have stronger effects on endosymbiont densities. To determine whether there is a genetic basis to the density differences, endosymbiont densities between aged CLas-negative females of two D. citri populations reared under standardized laboratory conditions were compared. Results suggested that inter-population variability in Wolbachia infection density is associated with the genotypes of the endosymbiont or the host. Findings from this work could facilitate understanding of D. citri-bacterial associations that may benefit the development of approaches for managing citrus greening, such as prevention of CLas transmission.

Measurement of inter- and intra-annual variability of landscape fire activity at a continental scale: the Australian case

NASA Astrophysics Data System (ADS)

Williamson, Grant J.; Prior, Lynda D.; Jolly, W. Matt; Cochrane, Mark A.; Murphy, Brett P.; Bowman, David M. J. S.

2016-03-01

Climate dynamics at diurnal, seasonal and inter-annual scales shape global fire activity, although difficulties of assembling reliable fire and meteorological data with sufficient spatio-temporal resolution have frustrated quantification of this variability. Using Australia as a case study, we combine data from 4760 meteorological stations with 12 years of satellite-derived active fire detections to determine day and night time fire activity, fire season start and end dates, and inter-annual variability, across 61 objectively defined climate regions in three climate zones (monsoon tropics, arid and temperate). We show that geographic patterns of landscape burning (onset and duration) are related to fire weather, resulting in a latitudinal gradient from the monsoon tropics in winter, through the arid zone in all seasons except winter, and then to the temperate zone in summer and autumn. Peak fire activity precedes maximum lightning activity by several months in all regions, signalling the importance of human ignitions in shaping fire seasons. We determined median daily McArthur forest fire danger index (FFDI50) for days and nights when fires were detected: FFDI50 varied substantially between climate zones, reflecting effects of fire management in the temperate zone, fuel limitation in the arid zone and abundance of flammable grasses in the monsoon tropical zone. We found correlations between the proportion of days when FFDI exceeds FFDI50 and the Southern Oscillation index across the arid zone during spring and summer, and Indian Ocean dipole mode index across south-eastern Australia during summer. Our study demonstrates that Australia has a long fire weather season with high inter-annual variability relative to all other continents, making it difficult to detect long term trends. It also provides a way of establishing robust baselines to track changes to fire seasons, and supports a previous conceptual model highlighting multi-temporal scale effects of climate in

Designed experiment evaluation of key variables affecting the cutting performance of rotary instruments.

PubMed

Funkenbusch, Paul D; Rotella, Mario; Ercoli, Carlo

2015-04-01

Laboratory studies of tooth preparation are often performed under a limited range of conditions involving single values for all variables other than the 1 being tested. In contrast, in clinical settings not all variables can be tightly controlled. For example, a new dental rotary cutting instrument may be tested in the laboratory by making a specific cut with a fixed force, but in clinical practice, the instrument must make different cuts with individual dentists applying a range of different forces. Therefore, the broad applicability of laboratory results to diverse clinical conditions is uncertain and the comparison of effects across studies is difficult. The purpose of this study was to examine the effect of 9 process variables on dental cutting in a single experiment, allowing each variable to be robustly tested over a range of values for the other 8 and permitting a direct comparison of the relative importance of each on the cutting process. The effects of 9 key process variables on the efficiency of a simulated dental cutting operation were measured. A fractional factorial experiment was conducted by using a computer-controlled, dedicated testing apparatus to simulate dental cutting procedures and Macor blocks as the cutting substrate. Analysis of Variance (ANOVA) was used to judge the statistical significance (α=.05). Five variables consistently produced large, statistically significant effects (target applied load, cut length, starting rpm, diamond grit size, and cut type), while 4 variables produced relatively small, statistically insignificant effects (number of cooling ports, rotary cutting instrument diameter, disposability, and water flow rate). The control exerted by the dentist, simulated in this study by targeting a specific level of applied force, was the single most important factor affecting cutting efficiency. Cutting efficiency was also significantly affected by factors simulating patient/clinical circumstances as well as hardware choices

Instrumental variables estimation of exposure effects on a time-to-event endpoint using structural cumulative survival models.

PubMed

Martinussen, Torben; Vansteelandt, Stijn; Tchetgen Tchetgen, Eric J; Zucker, David M

2017-12-01

The use of instrumental variables for estimating the effect of an exposure on an outcome is popular in econometrics, and increasingly so in epidemiology. This increasing popularity may be attributed to the natural occurrence of instrumental variables in observational studies that incorporate elements of randomization, either by design or by nature (e.g., random inheritance of genes). Instrumental variables estimation of exposure effects is well established for continuous outcomes and to some extent for binary outcomes. It is, however, largely lacking for time-to-event outcomes because of complications due to censoring and survivorship bias. In this article, we make a novel proposal under a class of structural cumulative survival models which parameterize time-varying effects of a point exposure directly on the scale of the survival function; these models are essentially equivalent with a semi-parametric variant of the instrumental variables additive hazards model. We propose a class of recursive instrumental variable estimators for these exposure effects, and derive their large sample properties along with inferential tools. We examine the performance of the proposed method in simulation studies and illustrate it in a Mendelian randomization study to evaluate the effect of diabetes on mortality using data from the Health and Retirement Study. We further use the proposed method to investigate potential benefit from breast cancer screening on subsequent breast cancer mortality based on the HIP-study. © 2017, The International Biometric Society.

Important variables for parents' postnatal sense of security: evaluating a new Swedish instrument (the PPSS instrument).

PubMed

Persson, Eva K; Dykes, Anna-Karin

2009-08-01

to evaluate dimensions of both parents' postnatal sense of security the first week after childbirth, and to determine associations between the PPSS instrument and different sociodemographic and situational background variables. evaluative, cross-sectional design. 113 mothers and 99 fathers with children live born at term, from five hospitals in southern Sweden. mothers and fathers had similar feelings concerning postnatal sense of security. Of the dimensions in the PPSS instrument, a sense of midwives'/nurses' empowering behaviour, a sense of one's own general well-being and a sense of the mother's well-being as experienced by the father were the most important dimensions for parents' experienced security. A sense of affinity within the family (for both parents) and a sense of manageable breast feeding (for mothers) were not significantly associated with their experienced security. A sense of participation during pregnancy and general anxiety were significantly associated background variables for postnatal sense of security for both parents. For the mothers, parity and a sense that the father was participating during pregnancy were also significantly associated. more focus on parents' participation during pregnancy as well as midwives'/nurses' empowering behaviour during the postnatal period will be beneficial for both parents' postnatal sense of security.

FHR Process Instruments

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

Holcomb, David Eugene

2015-01-01

Fluoride salt-cooled High temperature Reactors (FHRs) are entering into early phase engineering development. Initial candidate technologies have been identified to measure all of the required process variables. The purpose of this paper is to describe the proposed measurement techniques in sufficient detail to enable assessment of the proposed instrumentation suite and to support development of the component technologies. This paper builds upon the instrumentation chapter of the recently published FHR technology development roadmap. Locating instruments outside of the intense core radiation and high-temperature fluoride salt environment significantly decreases their environmental tolerance requirements. Under operating conditions, FHR primary coolant salt ismore » a transparent, low-vapor-pressure liquid. Consequently, FHRs can employ standoff optical measurements from above the salt pool to assess in-vessel conditions. For example, the core outlet temperature can be measured by observing the fuel s blackbody emission. Similarly, the intensity of the core s Cerenkov glow indicates the fission power level. Short-lived activation of the primary coolant provides another means for standoff measurements of process variables. The primary coolant flow and neutron flux can be measured using gamma spectroscopy along the primary coolant piping. FHR operation entails a number of process measurements. Reactor thermal power and core reactivity are the most significant variables for process control. Thermal power can be determined by measuring the primary coolant mass flow rate and temperature rise across the core. The leading candidate technologies for primary coolant temperature measurement are Au-Pt thermocouples and Johnson noise thermometry. Clamp-on ultrasonic flow measurement, that includes high-temperature tolerant standoffs, is a potential coolant flow measurement technique. Also, the salt redox condition will be monitored as an indicator of its corrosiveness. Both

Neurobiological degeneracy and affordance perception support functional intra-individual variability of inter-limb coordination during ice climbing.

PubMed

Seifert, Ludovic; Wattebled, Léo; Herault, Romain; Poizat, Germain; Adé, David; Gal-Petitfaux, Nathalie; Davids, Keith

2014-01-01

This study investigated the functional intra-individual movement variability of ice climbers differing in skill level to understand how icefall properties were used by participants as affordances to adapt inter-limb coordination patterns during performance. Seven expert climbers and seven beginners were observed as they climbed a 30 m icefall. Movement and positioning of the left and right hand ice tools, crampons and the climber's pelvis over the first 20 m of the climb were recorded and digitized using video footage from a camera (25 Hz) located perpendicular to the plane of the icefall. Inter-limb coordination, frequency and types of action and vertical axis pelvis displacement exhibited by each climber were analysed for the first five minutes of ascent. Participant perception of climbing affordances was assessed through: (i) calculating the ratio between exploratory movements and performed actions, and (ii), identifying, by self-confrontation interviews, the perceptual variables of environmental properties, which were significant to climbers for their actions. Data revealed that experts used a wider range of upper and lower limb coordination patterns, resulting in the emergence of different types of action and fewer exploratory movements, suggesting that effective holes in the icefall provided affordances to regulate performance. In contrast, beginners displayed lower levels of functional intra-individual variability of motor organization, due to repetitive swinging of ice tools and kicking of crampons to achieve and maintain a deep anchorage, suggesting lack of perceptual attunement and calibration to environmental properties to support climbing performance.

The Greenland Sea Odden: Intra- and inter-annual variability

USGS Publications Warehouse

Russell, C.A.; Fischer, K.W.; Shuchman, R.A.; Josberger, E.G.

1997-01-01

The "Odden" is a large sea ice feature that forms in the East Greenland Sea which generally forms at the beginning of the winter season and can cover 300,000 km2. Throughout the winter, the outer edge of the Odden may advance and retreat by several hundred kilometers on time scales of a few days to weeks. Satellite passive microwave observations from 1978 through 1995 provide a continuous record of the spatial and temporal variations of this extremely dynamic phenomenon. The 17 year record shows both strong inter- and intra-annual variations in Odden extent and temporal behavior. An analysis of the satellite passive microwave derived ice area and extent time series along with meteorological data from the Arctic Drifting Buoy Network determined the meteorological forcing required for Odden growth, maintenance and decay. The key meteorological parameters which cause the rapid ice formation and decay associated with the Odden are, in order of importance, air temperature, wind speed, and wind direction. Atmospheric pressure was found not to play a significant role in the Odden events. Air temperature and wind direction are the dominant variables with temperatures below -9.5??C and winds from the west required to trigger significant Odden ice formation events. ??2004 Copyright SPIE - The International Society for Optical Engineering.

Practical methodological guide for hydrometric inter-laboratory organisation

NASA Astrophysics Data System (ADS)

Besson, David; Bertrand, Xavier

2015-04-01

Discharge measurements performed by the French governmental hydrometer team feed a national database. This data is available for general river flows knowkedge, flood forecasting, low water survey, statistical calculations flow, control flow regulatory and many other uses. Regularly checking the measurements quality and better quantifying its accuracy is therefore an absolute need. The practice of inter-laboratory comparison in hydrometry particularly developed during the last decade. Indeed, discharge measurement can not easily be linked to a standard. Therefore, on-site measurement accuracy control is very difficult. Inter-laboratory comparison is thus a practical solution to this issue. However, it needs some regulations in order to ease its practice and legitimize its results. To do so, the French government hydrometrics teams produced a practical methodological guide for hydrometric inter-laboratory organisation in destination of hydrometers community in view of ensure the harmonization of inter-laboratory comparison practices for different materials (ADCP, current meter on wadind rod or gauging van, tracer dilution, surface speed) and flow range (flood, low water). Ensure the results formalization and banking. The realisation of this practice guide is grounded on the experience of the governmental teams & their partners (or fellows), following existing approaches (Doppler group especially). The guide is designated to validate compliance measures and identify outliers : Hardware, methodological, environmental, or human. Inter-laboratory comparison provides the means to verify the compliance of the instruments (devices + methods + operators) and provides methods to determine an experimental uncertainty of the tested measurement method which is valid only for the site and the measurement conditions but does not address the calibration or periodic monitoring of the few materials. After some conceptual definitions, the guide describes the different stages of an

An introduction to instrumental variables analysis: part 1.

PubMed

Bennett, Derrick A

2010-01-01

There are several examples in the medical literature where the associations of treatment effects predicted by observational studies have been refuted by evidence from subsequent large-scale randomised trials. This is because of the fact that non-experimental studies are subject to confounding - and confounding cannot be entirely eliminated even if all known confounders have been measured in the study as there may be unknown confounders. The aim of this 2-part methodological primer is to introduce an emerging methodology for estimating treatment effects using observational data in the absence of good randomised evidence known as the method of instrumental variables. Copyright © 2010 S. Karger AG, Basel.

Inter-seasonal variability in baseflow recession rates: The role of aquifer antecedent storage in central California watersheds

NASA Astrophysics Data System (ADS)

Bart, Ryan; Hope, Allen

2014-11-01

Baseflow recession rates vary inter-seasonally in many watersheds. This variability is generally associated with changes in evapotranspiration; however, an additional and less studied control over inter-seasonal baseflow recession rates is the effect of aquifer antecedent storage. Understanding the role of aquifer antecedent storage on baseflow recession rates is crucial for Mediterranean-climate regions, where seasonal asynchronicity of precipitation and energy levels produces large inter-seasonal differences in aquifer storage. The primary objective of this study was to elucidate the relation between aquifer antecedent storage and baseflow recession rates in four central California watersheds using antecedent streamflow as a surrogate for watershed storage. In addition, a parsimonious storage-discharge model consisting of two nonlinear stores in parallel was developed as a heuristic tool for interpreting the empirical results and providing insight into how inter-seasonal changes in aquifer antecedent storage may affect baseflow recession rates. Antecedent streamflow cumulated from the beginning of the wateryear was found to be the strongest predictor of baseflow recession rates, indicating that inter-seasonal differences in aquifer storage are a key control on baseflow recession rates in California watersheds. Baseflow recession rates and antecedent streamflow exhibited a negative power-law relation, with baseflow recession rates decreasing by up to two orders of magnitude as antecedent streamflow levels increased. Inference based on the storage-discharge model indicated that the dominant source of recession flow shifted from small, rapid response aquifers at the beginning of the wet season to large, seasonal aquifers as the wet season progressed. Aquifer antecedent storage in California watersheds should be accounted for along with evapotranspiration when characterizing baseflow recession rates.

Instrumental variables as bias amplifiers with general outcome and confounding.

PubMed

Ding, P; VanderWeele, T J; Robins, J M

2017-06-01

Drawing causal inference with observational studies is the central pillar of many disciplines. One sufficient condition for identifying the causal effect is that the treatment-outcome relationship is unconfounded conditional on the observed covariates. It is often believed that the more covariates we condition on, the more plausible this unconfoundedness assumption is. This belief has had a huge impact on practical causal inference, suggesting that we should adjust for all pretreatment covariates. However, when there is unmeasured confounding between the treatment and outcome, estimators adjusting for some pretreatment covariate might have greater bias than estimators without adjusting for this covariate. This kind of covariate is called a bias amplifier, and includes instrumental variables that are independent of the confounder, and affect the outcome only through the treatment. Previously, theoretical results for this phenomenon have been established only for linear models. We fill in this gap in the literature by providing a general theory, showing that this phenomenon happens under a wide class of models satisfying certain monotonicity assumptions. We further show that when the treatment follows an additive or multiplicative model conditional on the instrumental variable and the confounder, these monotonicity assumptions can be interpreted as the signs of the arrows of the causal diagrams.

Spatial variability of metals in the inter-tidal sediments of the Medway Estuary, Kent, UK.

PubMed

Spencer, Kate L

2002-09-01

Concentrations of major and trace metals were determined in eight sediment cores collected from the inter-tidal zone of the Medway Estuary, Kent, UK. Metal associations and potential sources have been investigated using principal component analysis. These data provide the first detailed geochemical survey of recent sediments in the Medway Estuary. Metal concentrations in surface sediments lie in the mid to lower range for UK estuarine sediments indicating that the Medway receives low but appreciable contaminant inputs. Vertical metal distributions reveal variable redox zonation across the estuary and historically elevated anthropogenic inputs. Peak concentrations of Cu, Pb and Zn can be traced laterally across the estuary and their positions indicate periods of past erosion and/or non-deposition. However, low rates of sediment accumulation do not allow these sub surface maxima to be used as accurate geochemical marker horizons. The salt marshes and inter-tidal mud flats in the Medway Estuary are experiencing erosion, however the erosion of historically contaminated sediments is unlikely to re-release significant amounts of heavy metals to the estuarine system.

A selective review of the first 20 years of instrumental variables models in health-services research and medicine.

PubMed

Cawley, John

2015-01-01

The method of instrumental variables (IV) is useful for estimating causal effects. Intuitively, it exploits exogenous variation in the treatment, sometimes called natural experiments or instruments. This study reviews the literature in health-services research and medical research that applies the method of instrumental variables, documents trends in its use, and offers examples of various types of instruments. A literature search of the PubMed and EconLit research databases for English-language journal articles published after 1990 yielded a total of 522 original research articles. Citations counts for each article were derived from the Web of Science. A selective review was conducted, with articles prioritized based on number of citations, validity and power of the instrument, and type of instrument. The average annual number of papers in health services research and medical research that apply the method of instrumental variables rose from 1.2 in 1991-1995 to 41.8 in 2006-2010. Commonly-used instruments (natural experiments) in health and medicine are relative distance to a medical care provider offering the treatment and the medical care provider's historic tendency to administer the treatment. Less common but still noteworthy instruments include randomization of treatment for reasons other than research, randomized encouragement to undertake the treatment, day of week of admission as an instrument for waiting time for surgery, and genes as an instrument for whether the respondent has a heritable condition. The use of the method of IV has increased dramatically in the past 20 years, and a wide range of instruments have been used. Applications of the method of IV have in several cases upended conventional wisdom that was based on correlations and led to important insights about health and healthcare. Future research should pursue new applications of existing instruments and search for new instruments that are powerful and valid.

Biomechanical effects of a 2 suture-pass medial inter-implant mattress on transosseous-equivalent rotator cuff repair and considerations for a "technical efficiency ratio".

PubMed

Park, Maxwell C; Peterson, Alexander; Patton, John; McGarry, Michelle H; Park, Chong J; Lee, Thay Q

2014-03-01

Rotator cuff repair involving fewer tendon suture passes without compromising biomechanical performance would represent a technical advancement. An inter-implant "medial pulley-mattress" transosseous-equivalent (MP-TOE) repair requiring fewer tendon suture-passes was hypothesized to provide equivalent biomechanical characteristics compared to the control. In 6 human cadaveric shoulders, a transosseous-equivalent (TOE) repair (control) was performed utilizing 2 separate medial mattresses resulting in 4 tendon-bridging sutures. In 6 matched-pairs, 2 single-loaded anchors were used to create a medial inter-implant mattress construct (all sutures shuttled in 1 tendon pass per anchor)-after knot-tying, the same tendon-bridging pattern as the control was created. A materials testing machine cyclically loaded each repair from 10-180 N for 30 cycles; each repair subsequently underwent failure testing. Gap and strain were measured with a video digitizing system. A "technical efficiency ratio" (TER) was defined as: (#knots + #suture passes + #suture limbs)/#fixation points. Cyclic and failure testing demonstrated no significant differences between constructs. Gap formation at cycle 30 was 5.3 ± 0.8 mm (TOE) and 5.0 ± 0.3 mm (MP-TOE) (P = .62). Cycle 30 anterior strain values were -16.0 ± 7.3% (TOE) and -15.8 ± 6.6% (MP-TOE) (P = .99). Yield loads were 208.7 ± 2.7 N (TOE) and 204.0 ± 1.3 N (MP-TOE) (P = .17). Mode of failure demonstrated less tendon cut-out with the MP-TOE repair. The MP-TOE repair has a TER of 2.0 vs 2.5 for the control. The MP-TOE repair requiring fewer tendon suture passes, yet creating an additional inter-implant mattress configuration, is biomechanically equivalent to the original TOE technique, and may limit failure with improved medial load-sharing capacity. A TER may help quantify technical ease and help standardize comparisons between repair techniques. Copyright © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights

The contextual effects of social capital on health: a cross-national instrumental variable analysis.

PubMed

Kim, Daniel; Baum, Christopher F; Ganz, Michael L; Subramanian, S V; Kawachi, Ichiro

2011-12-01

Past research on the associations between area-level/contextual social capital and health has produced conflicting evidence. However, interpreting this rapidly growing literature is difficult because estimates using conventional regression are prone to major sources of bias including residual confounding and reverse causation. Instrumental variable (IV) analysis can reduce such bias. Using data on up to 167,344 adults in 64 nations in the European and World Values Surveys and applying IV and ordinary least squares (OLS) regression, we estimated the contextual effects of country-level social trust on individual self-rated health. We further explored whether these associations varied by gender and individual levels of trust. Using OLS regression, we found higher average country-level trust to be associated with better self-rated health in both women and men. Instrumental variable analysis yielded qualitatively similar results, although the estimates were more than double in size in both sexes when country population density and corruption were used as instruments. The estimated health effects of raising the percentage of a country's population that trusts others by 10 percentage points were at least as large as the estimated health effects of an individual developing trust in others. These findings were robust to alternative model specifications and instruments. Conventional regression and to a lesser extent IV analysis suggested that these associations are more salient in women and in women reporting social trust. In a large cross-national study, our findings, including those using instrumental variables, support the presence of beneficial effects of higher country-level trust on self-rated health. Previous findings for contextual social capital using traditional regression may have underestimated the true associations. Given the close linkages between self-rated health and all-cause mortality, the public health gains from raising social capital within and across

The contextual effects of social capital on health: a cross-national instrumental variable analysis

PubMed Central

Kim, Daniel; Baum, Christopher F; Ganz, Michael; Subramanian, S V; Kawachi, Ichiro

2011-01-01

Past observational studies of the associations of area-level/contextual social capital with health have revealed conflicting findings. However, interpreting this rapidly growing literature is difficult because estimates using conventional regression are prone to major sources of bias including residual confounding and reverse causation. Instrumental variable (IV) analysis can reduce such bias. Using data on up to 167 344 adults in 64 nations in the European and World Values Surveys and applying IV and ordinary least squares (OLS) regression, we estimated the contextual effects of country-level social trust on individual self-rated health. We further explored whether these associations varied by gender and individual levels of trust. Using OLS regression, we found higher average country-level trust to be associated with better self-rated health in both women and men. Instrumental variable analysis yielded qualitatively similar results, although the estimates were more than double in size in women and men using country population density and corruption as instruments. The estimated health effects of raising the percentage of a country's population that trusts others by 10 percentage points were at least as large as the estimated health effects of an individual developing trust in others. These findings were robust to alternative model specifications and instruments. Conventional regression and to a lesser extent IV analysis suggested that these associations are more salient in women and in women reporting social trust. In a large cross-national study, our findings, including those using instrumental variables, support the presence of beneficial effects of higher country-level trust on self-rated health. Past findings for contextual social capital using traditional regression may have underestimated the true associations. Given the close linkages between self-rated health and all-cause mortality, the public health gains from raising social capital within countries may

Visualising inter-subject variability in fMRI using threshold-weighted overlap maps

NASA Astrophysics Data System (ADS)

Seghier, Mohamed L.; Price, Cathy J.

2016-02-01

Functional neuroimaging studies are revealing the neural systems sustaining many sensory, motor and cognitive abilities. A proper understanding of these systems requires an appreciation of the degree to which they vary across subjects. Some sources of inter-subject variability might be easy to measure (demographics, behavioural scores, or experimental factors), while others are more difficult (cognitive strategies, learning effects, and other hidden sources). Here, we introduce a simple way of visualising whole-brain consistency and variability in brain responses across subjects using threshold-weighted voxel-based overlap maps. The output quantifies the proportion of subjects activating a particular voxel or region over a wide range of statistical thresholds. The sensitivity of our approach was assessed in 30 healthy adults performing a matching task with their dominant hand. We show how overlap maps revealed many effects that were only present in a subsample of our group; we discuss how overlap maps can provide information that may be missed or misrepresented by standard group analysis, and how this information can help users to understand their data. In particular, we emphasize that functional overlap maps can be particularly useful when it comes to explaining typical (or atypical) compensatory mechanisms used by patients following brain damage.

Assessing variability in chemical acute toxicity of unionid mussels: Influence of intra- and inter-laboratory testing, life stage, and species

USGS Publications Warehouse

Raimondo, Sandy; Lilavois, Crystal R.; Lee, Larisa; Augspurger, Tom; Wang, Ning; Ingersoll, Christopher G.; Bauer, Candice R.; Hammer, Edward J.; Barron, Mace G.

2016-01-01

We developed a toxicity database for unionid mussels to examine the extent of intra- and inter-laboratory variability in acute toxicity tests with mussel larvae (glochidia) and juveniles; the extent of differential sensitivity of the two life stages; and the variation in sensitivity among commonly tested mussels (Lampsilis siliquoidea, Utterbackia imbecillis, Villosa iris), commonly tested cladocerans (Daphnia magna, Ceriodaphnia dubia) and fish (Oncorhynchus mykiss, Pimephales promelas, Lepomis macrochirus). The results of these analyses indicate intra-laboratory variability for median effect concentrations (EC50) averaged about 2 fold for both life stages, while inter-laboratory variability averaged 3.6 fold for juvenile mussels and 6.3 fold for glochidia. The EC50s for juveniles and glochidia were within a factor of 2 of each other for 50% of paired records across chemicals, with juveniles more sensitive than glochidia by more than 2 fold for 33% of the comparisons made between life stages. There was a high concurrence of the sensitivity of commonly tested L. siliquoidea, U. imbecillis, and V. iris to that of other mussels. However, this concurrence decreases as the taxonomic distance of the commonly tested cladocerans and fish to mussels increases. The compiled mussel database and determination of data variability will advance risk assessments by including more robust species sensitivity distributions, interspecies correlation estimates, and availability of taxon-specific empirically derived application factors for risk assessment.

Inter-decadal change in potential predictability of the East Asian summer monsoon

NASA Astrophysics Data System (ADS)

Li, Jiao; Ding, Ruiqiang; Wu, Zhiwei; Zhong, Quanjia; Li, Baosheng; Li, Jianping

2018-05-01

The significant inter-decadal change in potential predictability of the East Asian summer monsoon (EASM) has been investigated using the signal-to-noise ratio method. The relatively low potential predictability appears from the early 1950s through the late 1970s and during the early 2000s, whereas the potential predictability is relatively high from the early 1980s through the late 1990s. The inter-decadal change in potential predictability of the EASM can be attributed mainly to variations in the external signal of the EASM. The latter is mostly caused by the El Niño-Southern Oscillation (ENSO) inter-decadal variability. As a major external signal of the EASM, the ENSO inter-decadal variability experiences phase transitions from negative to positive phases in the late 1970s, and to negative phases in the late 1990s. Additionally, ENSO is generally strong (weak) during a positive (negative) phase of the ENSO inter-decadal variability. The strong ENSO is expected to have a greater influence on the EASM, and vice versa. As a result, the potential predictability of the EASM tends to be high (low) during a positive (negative) phase of the ENSO inter-decadal variability. Furthermore, a suite of Pacific Pacemaker experiments suggests that the ENSO inter-decadal variability may be a key pacemaker of the inter-decadal change in potential predictability of the EASM.

Instrument Noise Simulation for GRACE Follow-On

NASA Astrophysics Data System (ADS)

Darbeheshti, N.; Mueller, V.; Wegener, H.; Hewitson, M.; Heinzel, G.; Naeimi, M.; Flury, J.

2016-12-01

The quality of the temporal gravity field from GRACE Follow-On mission depends on its multi-sensor system consisting of inter-satellite ranging with microwave and laser ranging instrument, GNSS orbit tracking, accelerometry, and attitude sensing. In this presentation, the noise models for GRACE Follow-On major instruments are described and their effect on the estimation of Earth's gravity field accuracy are discussed. To do this the spectrum of the instruments noise models has been related to the spectrum of the disturbing potential of the Earth's gravity field. The instrument noise models are available to the geodesy community through GRACE Follow-On mock data challenges. The performance of gravity field recovery approaches can be tested by comparing observation residuals to the simulated instrument noises. The instrument noise models will also provide valuable insight for inter-satellite ranging configurations beyond GRACE Follow-On.

Technical variables in high-throughput miRNA expression profiling: much work remains to be done.

PubMed

Nelson, Peter T; Wang, Wang-Xia; Wilfred, Bernard R; Tang, Guiliang

2008-11-01

MicroRNA (miRNA) gene expression profiling has provided important insights into plant and animal biology. However, there has not been ample published work about pitfalls associated with technical parameters in miRNA gene expression profiling. One source of pertinent information about technical variables in gene expression profiling is the separate and more well-established literature regarding mRNA expression profiling. However, many aspects of miRNA biochemistry are unique. For example, the cellular processing and compartmentation of miRNAs, the differential stability of specific miRNAs, and aspects of global miRNA expression regulation require specific consideration. Additional possible sources of systematic bias in miRNA expression studies include the differential impact of pre-analytical variables, substrate specificity of nucleic acid processing enzymes used in labeling and amplification, and issues regarding new miRNA discovery and annotation. We conclude that greater focus on technical parameters is required to bolster the validity, reliability, and cultural credibility of miRNA gene expression profiling studies.

Work and Inter-subjectivity: a theoretical reflection on its dialectics in the field of health and nursing.

PubMed

Carvalho, Brígida Gimenez; Peduzzi, Marina; Mandú, Edir Nei Teixeira; Ayres, José Ricardo de Carvalho Mesquita

2012-01-01

This theoretical reflection intends to show the inter-subjective relationship that takes place in health and nursing practices under the following theoretical perspectives: Institutional Analysis, Psychodynamics of Labor and the Theory of Communicative Action, with an emphasis on the latter. Linking these concepts to the Marxist approach to work in the field of health emerges from recognizing the need for its continuous reconstruction-in this case, with a view to understand the interaction and communication intrinsic to work in action. The theory of Communicative Action seeks to consider these two inextricable dimensions: work as productive action and as interaction. The first corresponds to instrumental action based on technical rules with a production-guided rationale. The second refers to the interaction that takes place as communicative action and seeks understanding among subjects. We assume that adopting this theoretical perspective in the analysis of health and nursing practices opens new possibilities for clarifying its social and historical process and inter-subjective connections.

Inter- and intrascanner variability of pulmonary nodule volumetry on low-dose 64-row CT: an anthropomorphic phantom study

PubMed Central

Xie, X; Willemink, M J; Zhao, Y; de Jong, P A; van Ooijen, P M A; Oudkerk, M; Greuter, M J W

2013-01-01

Objective: To assess inter- and intrascanner variability in volumetry of solid pulmonary nodules in an anthropomorphic thoracic phantom using low-dose CT. Methods: Five spherical solid artificial nodules [diameters 3, 5, 8, 10 and 12 mm; CT density +100 Hounsfield units (HU)] were randomly placed inside an anthropomorphic thoracic phantom in different combinations. The phantom was examined on two 64-row multidetector CT (64-MDCT) systems (CT-A and CT-B) from different vendors with a low-dose protocol. Each CT examination was performed three times. The CT examinations were evaluated twice by independent blinded observers. Nodule volume was semi-automatically measured by dedicated software. Interscanner variability was evaluated by Bland–Altman analysis and expressed as 95% confidence interval (CI) of relative differences. Intrascanner variability was expressed as 95% CI of relative variation from the mean. Results: No significant difference in CT-derived volume was found between CT-A and CT-B, except for the 3-mm nodules (p<0.05). The 95% CI of interscanner variability was within ±41.6%, ±18.2% and ±4.9% for 3, 5 and ≥8 mm nodules, respectively. The 95% CI of intrascanner variability was within ±28.6%, ±13.4% and ±2.6% for 3, 5 and ≥8 mm nodules, respectively. Conclusion: Different 64-MDCT scanners in low-dose settings yield good agreement in volumetry of artificial pulmonary nodules between 5 mm and 12 mm in diameter. Inter- and intrascanner variability decreases at a larger nodule size to a maximum of 4.9% for ≥8 mm nodules. Advances in knowledge: The commonly accepted cut-off of 25% to determine nodule growth has the potential to be reduced for ≥8 mm nodules. This offers the possibility of reducing the interval for repeated CT scans in lung cancer screenings. PMID:23884758

Measuring health related quality of life (HRQoL) in community and facility-based care settings with the interRAI assessment instruments: development of a crosswalk to HUI3.

PubMed

Hirdes, John P; Bernier, Julie; Garner, Rochelle; Finès, Philippe; Jantzi, Micaela

2018-05-01

Health-related quality of life (HRQoL) measures are of interest because they can be used to describe health of populations and represent a broader health outcome for population health analyses than mortality rates or life expectancy. The most widely used measure of HRQoL for deriving estimates of health-adjusted life expectancy is the Health Utilities Index Mark 3 (HUI3). The HUI3 is available in most national surveys administered by Statistics Canada, and has been used as part of a microsimulation model to examine the impact of neurological conditions over the life course. Persons receiving home care and nursing home services are often not well-represented in these surveys; however, interRAI assessment instruments are now used as part of normal clinical practice in these settings for nine Canadian provinces/territories. Building on previous research that developed a HUI2 crosswalk for the interRAI assessments, the present study examined a new interRAI HRQoL index crosswalked to the HUI3. interRAI and survey data were used to examine the distributional properties of global and domain-specific interRAI HRQoL and HUI3 index scores, respectively. Three populations were considered: well-elderly persons not receiving home care, home care clients and nursing home residents. The mean HUI3 and interRAI HRQoL index global scores declined from independent healthy older persons to home care clients, followed by nursing home residents. For the home care and nursing home populations, the interRAI HRQoL global estimates tended to be lower than HUI3 global scores obtained from survey respondents. While there were some statistically significant age, sex and diagnostic group differences in global scores and within attributes, the most notable differences were between populations from different care settings. The present study provides strong evidence for the validity of the interRAI HRQoL based on comparisons of distributional properties with those obtained with survey data based

Regularization Methods for High-Dimensional Instrumental Variables Regression With an Application to Genetical Genomics

PubMed Central

Lin, Wei; Feng, Rui; Li, Hongzhe

2014-01-01

In genetical genomics studies, it is important to jointly analyze gene expression data and genetic variants in exploring their associations with complex traits, where the dimensionality of gene expressions and genetic variants can both be much larger than the sample size. Motivated by such modern applications, we consider the problem of variable selection and estimation in high-dimensional sparse instrumental variables models. To overcome the difficulty of high dimensionality and unknown optimal instruments, we propose a two-stage regularization framework for identifying and estimating important covariate effects while selecting and estimating optimal instruments. The methodology extends the classical two-stage least squares estimator to high dimensions by exploiting sparsity using sparsity-inducing penalty functions in both stages. The resulting procedure is efficiently implemented by coordinate descent optimization. For the representative L1 regularization and a class of concave regularization methods, we establish estimation, prediction, and model selection properties of the two-stage regularized estimators in the high-dimensional setting where the dimensionality of co-variates and instruments are both allowed to grow exponentially with the sample size. The practical performance of the proposed method is evaluated by simulation studies and its usefulness is illustrated by an analysis of mouse obesity data. Supplementary materials for this article are available online. PMID:26392642

Inter-rater reliability of measures to characterize the tobacco retail environment in Mexico.

PubMed

Hall, Marissa G; Kollath-Cattano, Christy; Reynales-Shigematsu, Luz Myriam; Thrasher, James F

2015-01-01

To evaluate the inter-rater reliability of a data collection instrument to assess the tobacco retail environment in Mexico, after major marketing regulations were implemented. In 2013, two data collectors independently evaluated 21 stores in two census tracts, through a data collection instrument that assessed the presence of price promotions, whether single cigarettes were sold, the number of visible advertisements, the presence of signage prohibiting the sale of cigarettes to minors, and characteristics of cigarette pack displays. We evaluated the inter-rater reliability of the collected data, through the calculation of metrics such as intraclass correlation coefficient, percent agreement, Cohen's kappa and Krippendorff's alpha. Most measures demonstrated substantial or perfect inter-rater reliability. Our results indicate the potential utility of the data collection instrument for future point-of-sale research.

The Intra-Rater Reliability of Nine Content-Validated Technical Skill Assessment Instruments (TSAI) for Athletic Taping Skills

ERIC Educational Resources Information Center

Lagumen, Niko G.; Butterwick, Dale J.; Paskevich, David M.; Fung, Tak S.; Donnon, Tyrone L.

2008-01-01

Objective: To establish the intra-rater reliability of nine content-validated Technical Skill Assessment Instruments (TSAI) for the skills of athletic taping. Setting: University of Calgary. Subjects: Canadian Certified Athletic Therapists, CAT(C), with a mean ± SD of 9.6 ± 10.8 years as a CAT(C), 7.8 ± 10.9 years as a Supervisory Athletic…

PISA for Development Technical Strand A: Enhancement of PISA Cognitive Instruments. OECD Education Working Papers, No. 126

ERIC Educational Resources Information Center

Adams, Ray; Cresswell, John

2016-01-01

The OECD is planning to enhance existing PISA assessment instruments in reading, mathematics and science so that they will be more suitable to the context of developing countries. The main purpose of this paper is to identify the main technical issues associated with this aim. The paper reports detailed analysis of the existing PISA item pool and…

Central Corneal Thickness Reproducibility among Ten Different Instruments.

PubMed

Pierro, Luisa; Iuliano, Lorenzo; Gagliardi, Marco; Ambrosi, Alessandro; Rama, Paolo; Bandello, Francesco

2016-11-01

To assess agreement between one ultrasonic (US) and nine optical instruments for the measurement of central corneal thickness (CCT), and to evaluate intra- and inter-operator reproducibility. In this observational cross-sectional study, two masked operators measured CCT thickness twice in 28 healthy eyes. We used seven spectral-domain optical coherence tomography (SD-OCT) devices, one time-domain OCT, one Scheimpflug camera, and one US-based instrument. Inter- and intra-operator reproducibility was evaluated by intraclass correlation coefficient (ICC), coefficient of variation (CV), and Bland-Altman test analysis. Instrument-to-instrument reproducibility was determined by ANOVA for repeated measurements. We also tested how the devices disagreed regarding systemic bias and random error using a structural equation model. Mean CCT of all instruments ranged from 536 ± 42 μm to 577 ± 40 μm. An instrument-to-instrument correlation test showed high values among the 10 investigated devices (correlation coefficient range 0.852-0.995; p values <0.0001 in all cases). The highest correlation coefficient values were registered between 3D OCT-2000 Topcon-Spectral OCT/SLO Opko (0.995) and Cirrus HD-OCT Zeiss-RS-3000 Nidek (0.995), whereas the lowest were seen between SS-1000 CASIA and Spectral OCT/SLO Opko (0.852). ICC and CV showed excellent inter- and intra-operator reproducibility for all optic-based devices, except for the US-based device. Bland-Altman analysis demonstrated low mean biases between operators. Despite highlighting good intra- and inter-operator reproducibility, we found that a scale bias between instruments might interfere with thorough CCT monitoring. We suggest that optimal monitoring is achieved with the same operator and the same device.

An Instrumental Perspective on CSCL Systems

ERIC Educational Resources Information Center

Lonchamp, Jacques

2012-01-01

The theory of instrumental genesis of Rabardel relates the social and the technical through the concept of instrument. An instrument is defined as a mixed entity made up by an artifact, the technical/material part, and a set of utilization schemes, the social/behavioural part, which both result from users' constructive activities. This theory is…

Invited Commentary: Using Financial Credits as Instrumental Variables for Estimating the Causal Relationship Between Income and Health.

PubMed

Pega, Frank

2016-05-01

Social epidemiologists are interested in determining the causal relationship between income and health. Natural experiments in which individuals or groups receive income randomly or quasi-randomly from financial credits (e.g., tax credits or cash transfers) are increasingly being analyzed using instrumental variable analysis. For example, in this issue of the Journal, Hamad and Rehkopf (Am J Epidemiol. 2016;183(9):775-784) used an in-work tax credit called the Earned Income Tax Credit as an instrument to estimate the association between income and child development. However, under certain conditions, the use of financial credits as instruments could violate 2 key instrumental variable analytic assumptions. First, some financial credits may directly influence health, for example, through increasing a psychological sense of welfare security. Second, financial credits and health may have several unmeasured common causes, such as politics, other social policies, and the motivation to maximize the credit. If epidemiologists pursue such instrumental variable analyses, using the amount of an unconditional, universal credit that an individual or group has received as the instrument may produce the most conceptually convincing and generalizable evidence. However, other natural income experiments (e.g., lottery winnings) and other methods that allow better adjustment for confounding might be more promising approaches for estimating the causal relationship between income and health. © The Author 2016. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Analytical variability of estimated platelet counts on canine blood smears.

PubMed

Paltrinieri, Saverio; Paciletti, Veronica; Zambarbieri, Jari

2018-06-04

The analytical variability of estimated platelet counts in dogs has not been reported. The purpose of this study was to assess the magnitude of analytical imprecision of platelet estimates and the possible impact of this imprecision on clinical decisions. Three independent observers counted the number of platelets in 3 different areas (LE = lateral edge; CM = central monolayer; FE = feathered edge) of 30 canine blood smears with different instrumental platelet counts. The coefficient of variation (CV) for each observer was calculated in different areas of each smear (intra-observer variability), among different regions of each smear (inter-area variability), and among different observers in each area (inter-observer variability). The influence of these variabilities on the classification of platelet estimates as adequate, increased, or decreased was also assessed. The CVs recorded in the different areas by each observer ranged from 8% to 88% and were negatively correlated (P < .001, r = -.65) with the mean number of platelets per field. The mean platelet number was significantly lower in the FE and significantly higher in the CM compared with the LE, but the magnitude of this difference varied with the operators. The concordance among operators regarding platelet estimates was fair (k = 0.36) to substantial (k = 0.71) depending on the area. The overall inter-area concordance was moderate (k = 0.59). Platelet estimates suffer from high variability that could lead to patient misclassification. Therefore, guidelines to standardize the platelet estimate are needed. © 2018 American Society for Veterinary Clinical Pathology.

SU-E-J-275: Impact of the Intra and Inter Observer Variability in the Delineation of Parotid Glands On the Dose Calculation During Head and Neck Helical Tomotherapy

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

Jodda, A; Piotrowski, T

2014-06-01

Purpose: The intra- and inter-observer variability in delineation of the parotids on the kilo-voltage computed tomography (kVCT) and mega-voltage computed tomography (MVCT) were examined to establish their impact on the dose calculation during adaptive head and neck helical tomotherapy (HT). Methods: Three observers delineated left and right parotids for ten randomly selected patients with oropharynx cancer treated on HT. The pre-treatment kVCT and the MVCT from the first fraction of irradiation were selected to delineation. The delineation procedure was repeated three times by each observer. The parotids were delineated according to the institutional protocol. The analyses included intra-observer reproducibility andmore » inter-structure, -observer and -modality variability of the volume and dose. Results: The differences between the left and right parotid outlines were not statistically significant (p>0.3). The reproducibility of the delineation was confirmed for each observer on the kVCT (p>0.2) and on the MVCT (p>0.1). The inter-observer variability of the outlines was significant (p<0.001) as well as the inter-modality variability (p<0.006). The parotids delineated on the MVCT were 10% smaller than on the kVCT. The inter-observer variability of the parotids delineation did not affect the average dose (p=0.096 on the kVCT and p=0.176 on the MVCT). The dose calculated on the MVCT was higher by 3.3% than dose from the kVCT (p=0.009). Conclusion: Usage of the institutional protocols for the parotids delineation reduces intra-observer variability and increases reproducibility of the outlines. These protocols do not eliminate delineation differences between the observers, but these differences are not clinically significant and do not affect average doses in the parotids. The volumes of the parotids delineated on the MVCT are smaller than on the kVCT, which affects the differences in the calculated doses.« less

Detection Of Malware Collusion With Static Dependence Analysis On Inter-App Communication

DTIC Science & Technology

2016-12-08

DETECTION OF MALWARE COLLUSION WITH STATIC DEPENDENCE ANALYSIS ON INTER-APP COMMUNICATION VIRGINIA TECH DECEMBER 2016 FINAL TECHNICAL REPORT... DEPENDENCE ANALYSIS ON INTER-APP COMMUNICATION 5a. CONTRACT NUMBER FA8750-15-2-0076 5b. GRANT NUMBER N/A 5c. PROGRAM ELEMENT NUMBER 61101E 6. AUTHOR(S...exploited. 15. SUBJECT TERMS Malware Collusion; Inter-App Communication; Static Dependence Analysis 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF

Technical clarity in inter-agency negotiations: Lessons from four hydropower projects

USGS Publications Warehouse

Burkardt, Nina; Lamb, Berton Lee; Taylor, Jonathan G.; Waddle, Terry J.

1995-01-01

We investigated the effect of technical clarity on success in multi-party negotiations in the Federal Energy Regulatory Commission (FERC) licensing process. Technical clarity is the shared understanding of dimensions such as the geographic extent of the project, range of flows to be considered, important species and life stages, and variety of water uses considered. The results of four hydropower licensing consultations are reported. Key participants were interviewed to ascertain the level of technical clarity present during the consultations and the degree to which the consultations were successful. Technical clarity appears to be a prerequisite for successful outcomes. Factors that enhance technical clarity include simple project design, new rather than existing projects, precise definition of issues, a sense of urgency to reach agreement, a sense of fairness among participants, and consistency in participation. Negotiators should not neglect the critical pre-negotiation steps of defining technical issues and determining appropriate studies, deciding how to interpret studies, and agreeing on responses to study results.

Inter-laboratory consistency and variability in the buccal micronucleus cytome assay depends on biomarker scored and laboratory experience: results from the HUMNxl international inter-laboratory scoring exercise.

PubMed

Bolognesi, Claudia; Knasmueller, Siegfried; Nersesyan, Armen; Roggieri, Paola; Ceppi, Marcello; Bruzzone, Marco; Blaszczyk, Ewa; Mielzynska-Svach, Danuta; Milic, Mirta; Bonassi, Stefano; Benedetti, Danieli; Da Silva, Juliana; Toledo, Raphael; Salvadori, Daisy Maria Fávero; Groot de Restrepo, Helena; Filipic, Metka; Hercog, Klara; Aktas, Ayça; Burgaz, Sema; Kundi, Michael; Grummt, Tamara; Thomas, Philip; Hor, Maryam; Escudero-Fung, Maria; Holland, Nina; Fenech, Michael

2017-03-01

The buccal micronucleus cytome (BMNcyt) assay in uncultured exfoliated epithelial cells from oral mucosa is widely applied in biomonitoring human exposures to genotoxic agents and is also proposed as a suitable test for prescreening and follow-up of precancerous oral lesions. The main limitation of the assay is the large variability observed in the baseline values of micronuclei (MNi) and other nuclear anomalies mainly related to different scoring criteria. The aim of this international collaborative study, involving laboratories with different level of experience, was to evaluate the inter- and intra-laboratory variations in the BMNcyt parameters, using recently implemented guidelines, in scoring cells from the same pooled samples obtained from healthy subjects (control group) and from cancer patients undergoing radiotherapy (treated group). The results indicate that all laboratories correctly discriminated samples from the two groups by a significant increase of micronucleus (MN) and nuclear bud (NBUD) frequencies and differentiated binucleated (BN) cells, associated with the exposure to ionizing radiation. The experience of the laboratories was shown to play an important role in the identification of the different cell types and nuclear anomalies. MN frequency in differentiated mononucleated (MONO) and BN cells showed the greatest consistency among the laboratories and low variability was also detected in the frequencies of MONO and BN cells. A larger variability was observed in classifying the different cell types, indicating the subjectivity in the interpretation of some of the scoring criteria while reproducibility of the results between scoring sessions was very good. An inter-laboratory calibration exercise is strongly recommended before starting studies with BMNcyt assay involving multiple research centers. © The Author 2016. Published by Oxford University Press on behalf of the UK Environmental Mutagen Society. All rights reserved. For permissions

Inter-model variability in hydrological extremes projections for Amazonian sub-basins

NASA Astrophysics Data System (ADS)

Andres Rodriguez, Daniel; Garofolo, Lucas; Lázaro de Siqueira Júnior, José; Samprogna Mohor, Guilherme; Tomasella, Javier

2014-05-01

during the historical period, when feed with climate model data, were tested using descriptors of the Flow Duration Curves. The analyses of projected extreme values were carried out considering the nonstationarity of the GEV distribution parameters and compared with extremes events in present time. Results show inter-model variability in a broad dispersion on projected extreme's values. Such dispersion implies different degrees of socio-economic impacts associated to extreme hydrological events. Despite the no existence of one optimum result, this variability allows the analyses of adaptation strategies and its potential vulnerabilities.

Assessing variability in chemical acute toxicity of unionid mussels: Influence of intra- and inter-laboratory testing, life stage, and species - SETAC Abstract

EPA Science Inventory

We developed a toxicity database for unionid mussels to examine the extent of intra- and inter-laboratory variability in acute toxicity tests with mussel larvae (glochidia) and juveniles; the extent of differential sensitivity of the two life stages; and the variation in sensitiv...

Time dependent analysis of assay comparability: a novel approach to understand intra- and inter-site variability over time

NASA Astrophysics Data System (ADS)

Winiwarter, Susanne; Middleton, Brian; Jones, Barry; Courtney, Paul; Lindmark, Bo; Page, Ken M.; Clark, Alan; Landqvist, Claire

2015-09-01

We demonstrate here a novel use of statistical tools to study intra- and inter-site assay variability of five early drug metabolism and pharmacokinetics in vitro assays over time. Firstly, a tool for process control is presented. It shows the overall assay variability but allows also the following of changes due to assay adjustments and can additionally highlight other, potentially unexpected variations. Secondly, we define the minimum discriminatory difference/ratio to support projects to understand how experimental values measured at different sites at a given time can be compared. Such discriminatory values are calculated for 3 month periods and followed over time for each assay. Again assay modifications, especially assay harmonization efforts, can be noted. Both the process control tool and the variability estimates are based on the results of control compounds tested every time an assay is run. Variability estimates for a limited set of project compounds were computed as well and found to be comparable. This analysis reinforces the need to consider assay variability in decision making, compound ranking and in silico modeling.

Twenty Years of High-Resolution Sea Surface Temperature Imagery around Australia: Inter-Annual and Annual Variability

PubMed Central

Foster, Scott D.; Griffin, David A.; Dunstan, Piers K.

2014-01-01

The physical climate defines a significant portion of the habitats in which biological communities and species reside. It is important to quantify these environmental conditions, and how they have changed, as this will inform future efforts to study many natural systems. In this article, we present the results of a statistical summary of the variability in sea surface temperature (SST) time-series data for the waters surrounding Australia, from 1993 to 2013. We partition variation in the SST series into annual trends, inter-annual trends, and a number of components of random variation. We utilise satellite data and validate the statistical summary from these data to summaries of data from long-term monitoring stations and from the global drifter program. The spatially dense results, available as maps from the Australian Oceanographic Data Network's data portal (http://www.cmar.csiro.au/geonetwork/srv/en/metadata.show?id=51805), show clear trends that associate with oceanographic features. Noteworthy oceanographic features include: average warming was greatest off southern West Australia and off eastern Tasmania, where the warming was around 0.6°C per decade for a twenty year study period, and insubstantial warming in areas dominated by the East Australian Current, but this area did exhibit high levels of inter-annual variability (long-term trend increases and decreases but does not increase on average). The results of the analyses can be directly incorporated into (biogeographic) models that explain variation in biological data where both biological and environmental data are on a fine scale. PMID:24988444

The productivity of mental health care: an instrumental variable approach.

PubMed

Lu, Mingshan

1999-06-01

BACKGROUND: Like many other medical technologies and treatments, there is a lack of reliable evidence on treatment effectiveness of mental health care. Increasingly, data from non-experimental settings are being used to study the effect of treatment. However, as in a number of studies using non-experimental data, a simple regression of outcome on treatment shows a puzzling negative and significant impact of mental health care on the improvement of mental health status, even after including a large number of potential control variables. The central problem in interpreting evidence from real-world or non-experimental settings is, therefore, the potential "selection bias" problem in observational data set. In other words, the choice/quantity of mental health care may be correlated with other variables, particularly unobserved variables, that influence outcome and this may lead to a bias in the estimate of the effect of care in conventional models. AIMS OF THE STUDY: This paper addresses the issue of estimating treatment effects using an observational data set. The information in a mental health data set obtained from two waves of data in Puerto Rico is explored. The results using conventional models - in which the potential selection bias is not controlled - and that from instrumental variable (IV) models - which is what was proposed in this study to correct for the contaminated estimation from conventional models - are compared. METHODS: Treatment effectiveness is estimated in a production function framework. Effectiveness is measured as the improvement in mental health status. To control for the potential selection bias problem, IV approaches are employed. The essence of the IV method is to use one or more instruments, which are observable factors that influence treatment but do not directly affect patient outcomes, to isolate the effect of treatment variation that is independent of unobserved patient characteristics. The data used in this study are the first (1992

NGST Science Instruments and Process

NASA Technical Reports Server (NTRS)

Mather, John

1999-01-01

Possible NGST (Next Generation Space Telescope) instruments have been studied by NASA, ESA (European Space Agency), and CSA (Canadian Space Agency) teams, and their reports were presented at this meeting and published on the NGST web sites. The instrument capabilities will be evaluated by the Ad Hoc Science Working Group and the technical readiness will be reviewed by a technical panel. Recommendations will be made to the NASA Project Scientist, who will present a report for public comment. NASA. ESA, and the CSA will then allocate instrument, responsibilities in early 2000. NASA will choose its scientific investigations with instruments in 2002.

Cluster analysis and subgrouping to investigate inter-individual variability to non-invasive brain stimulation: a systematic review.

PubMed

Pellegrini, Michael; Zoghi, Maryam; Jaberzadeh, Shapour

2018-01-12

Cluster analysis and other subgrouping techniques have risen in popularity in recent years in non-invasive brain stimulation research in the attempt to investigate the issue of inter-individual variability - the issue of why some individuals respond, as traditionally expected, to non-invasive brain stimulation protocols and others do not. Cluster analysis and subgrouping techniques have been used to categorise individuals, based on their response patterns, as responder or non-responders. There is, however, a lack of consensus and consistency on the most appropriate technique to use. This systematic review aimed to provide a systematic summary of the cluster analysis and subgrouping techniques used to date and suggest recommendations moving forward. Twenty studies were included that utilised subgrouping techniques, while seven of these additionally utilised cluster analysis techniques. The results of this systematic review appear to indicate that statistical cluster analysis techniques are effective in identifying subgroups of individuals based on response patterns to non-invasive brain stimulation. This systematic review also reports a lack of consensus amongst researchers on the most effective subgrouping technique and the criteria used to determine whether an individual is categorised as a responder or a non-responder. This systematic review provides a step-by-step guide to carrying out statistical cluster analyses and subgrouping techniques to provide a framework for analysis when developing further insights into the contributing factors of inter-individual variability in response to non-invasive brain stimulation.

Predicting Student Performance in Web-Based Distance Education Courses Based on Survey Instruments Measuring Personality Traits and Technical Skills

ERIC Educational Resources Information Center

Hall, Michael

2008-01-01

Two common web-based surveys, "Is Online Learning Right for Me?' and "What Technical Skills Do I Need?", were combined into a single survey instrument and given to 228 on-campus and 83 distance education students. The students were enrolled in four different classes (business, computer information services, criminal justice, and…

Multi-Epoch Mid-Infrared Interferometric Observations of the Oxygen-rich Mira Variable Star RR Aql with the VLTI/MIDI Instrument

DTIC Science & Technology

2011-01-01

VLTI/ MIDI Instrument I. Karovicova,1,3 M. Wittkowski,1 D. A. Boboltz,2 E. Fossat,3 K. Ohnaka,4 and M. Scholz5,6 1European Southern Observatory...the oxygen-rich Mira variable RR Aql at 13 epochs covering 4 pulsation cycles with the MIDI instrument at the VLTI. We modeled the observed data...Variable Star RR Aql with the VLTI/ MIDI Instrument 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e

The impact of extracurricular activities participation on youth delinquent behaviors: An instrumental variables approach.

PubMed

Han, Sehee; Lee, Jonathan; Park, Kyung-Gook

2017-07-01

The purpose of this study was to examine the association between extracurricular activities (EA) participation and youth delinquency while tackling an endogeneity problem of EA participation. Using survey data of 12th graders in South Korea (n = 1943), this study employed an instrumental variables approach to address the self-selection problem of EA participation as the data for this study was based on an observational study design. We found a positive association between EA participation and youth delinquency based on conventional regression analysis. By contrast, we found a negative association between EA participation and youth delinquency based on an instrumental variables approach. These results indicate that caution should be exercised when we interpret the effect of EA participation on youth delinquency based on observational study designs. Copyright © 2017 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

SU-E-T-509: Inter-Observer and Inter-Modality Contouring Analysis for Organs at Risk for HDR Gynecological Brachytherapy

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

Sadeghi, P; Smith, W; Tom Baker Cancer Centre, Calgary, AB

2015-06-15

Purpose This study quantifies errors associated with MR-guided High Dose Rate (HDR) gynecological brachytherapy. Uncertainties in this treatment results from contouring, organ motion between imaging and treatment delivery, dose calculation, and dose delivery. We focus on interobserver and inter-modality variability in contouring and the motion of organs at risk (OARs) in the time span between the MR and CT scans (∼1 hour). We report the change in organ volume and position of center of mass (CM) between the two imaging modalities. Methods A total of 8 patients treated with MR-guided HDR brachytherapy were included in this study. Two observers contouredmore » the bladder and rectum on both MR and CT scans. The change in OAR volume and CM position between the MR and CT imaging sessions on both image sets were calculated. Results The absolute mean bladder volume change between the two imaging modalities is 67.1cc. The absolute mean inter-observer difference in bladder volume is much lower at 15.5cc (MR) and 11.0cc (CT). This higher inter-modality volume difference suggests a real change in the bladder filling between the two imaging sessions. Change in Rectum volume inter-observer standard error of means (SEM) is 3.18cc (MR) and 3.09cc (CT), while the inter-modality SEM is 3.65cc (observer 1), and 2.75cc (observer 2). The SEM for rectum CM position in the superior-inferior direction was approximately three times higher than in other directions for both the inter—observer (0.77 cm, 0.92 cm for observers 1 and 2, respectively) and inter-modality (0.91 cm, 0.95 cm for MR and CT, respectively) variability. Conclusion Bladder contours display good consistency between different observers on both CT and MR images. For rectum contouring the highest inconsistency stems from the observers’ choice of the superior-inferior borders. A complete analysis of a larger patient cohort will enable us to separate the true organ motion from the inter-observer variability.« less

Sources of Biased Inference in Alcohol and Drug Services Research: An Instrumental Variable Approach

PubMed Central

Schmidt, Laura A.; Tam, Tammy W.; Larson, Mary Jo

2012-01-01

Objective: This study examined the potential for biased inference due to endogeneity when using standard approaches for modeling the utilization of alcohol and drug treatment. Method: Results from standard regression analysis were compared with those that controlled for endogeneity using instrumental variables estimation. Comparable models predicted the likelihood of receiving alcohol treatment based on the widely used Aday and Andersen medical care–seeking model. Data were from the National Epidemiologic Survey on Alcohol and Related Conditions and included a representative sample of adults in households and group quarters throughout the contiguous United States. Results: Findings suggested that standard approaches for modeling treatment utilization are prone to bias because of uncontrolled reverse causation and omitted variables. Compared with instrumental variables estimation, standard regression analyses produced downwardly biased estimates of the impact of alcohol problem severity on the likelihood of receiving care. Conclusions: Standard approaches for modeling service utilization are prone to underestimating the true effects of problem severity on service use. Biased inference could lead to inaccurate policy recommendations, for example, by suggesting that people with milder forms of substance use disorder are more likely to receive care than is actually the case. PMID:22152672

Decoupling Solar Variability and Instrument Trends Using the Multiple Same-Irradiance-Level (MuSIL) Analysis Technique

NASA Astrophysics Data System (ADS)

Woods, Thomas N.; Eparvier, Francis G.; Harder, Jerald; Snow, Martin

2018-05-01

The solar spectral irradiance (SSI) dataset is a key record for studying and understanding the energetics and radiation balance in Earth's environment. Understanding the long-term variations of the SSI over timescales of the 11-year solar activity cycle and longer is critical for many Sun-Earth research topics. Satellite measurements of the SSI have been made since the 1970s, most of them in the ultraviolet, but recently also in the visible and near-infrared. A limiting factor for the accuracy of previous solar variability results is the uncertainties for the instrument degradation corrections, which need fairly large corrections relative to the amount of solar cycle variability at some wavelengths. The primary objective of this investigation has been to separate out solar cycle variability and any residual uncorrected instrumental trends in the SSI measurements from the Solar Radiation and Climate Experiment (SORCE) mission and the Thermosphere, Mesosphere, Ionosphere, Energetic, and Dynamics (TIMED) mission. A new technique called the Multiple Same-Irradiance-Level (MuSIL) analysis has been developed, which examines an SSI time series at different levels of solar activity to provide long-term trends in an SSI record, and the most common result is a downward trend that most likely stems from uncorrected instrument degradation. This technique has been applied to each wavelength in the SSI records from SORCE (2003 - present) and TIMED (2002 - present) to provide new solar cycle variability results between 27 nm and 1600 nm with a resolution of about 1 nm at most wavelengths. This technique, which was validated with the highly accurate total solar irradiance (TSI) record, has an estimated relative uncertainty of about 5% of the measured solar cycle variability. The MuSIL results are further validated with the comparison of the new solar cycle variability results from different solar cycles.

Design, testing and validation of an innovative web-based instrument to evaluate school meal quality.

PubMed

Patterson, Emma; Quetel, Anna-Karin; Lilja, Karin; Simma, Marit; Olsson, Linnea; Elinder, Liselotte Schäfer

2013-06-01

To develop a feasible, valid, reliable web-based instrument to objectively evaluate school meal quality in Swedish primary schools. The construct 'school meal quality' was operationalized by an expert panel into six domains, one of which was nutritional quality. An instrument was drafted and pilot-tested. Face validity was evaluated by the panel. Feasibility was established via a large national study. Food-based criteria to predict the nutritional adequacy of school meals in terms of fat quality, iron, vitamin D and fibre content were developed. Predictive validity was evaluated by comparing the nutritional adequacy of school menus based on these criteria with the results from a nutritional analysis. Inter-rater reliability was also assessed. The instrument was developed between 2010 and 2012. It is designed for use in all primary schools by school catering and/or management representatives. A pilot-test of eighty schools in Stockholm (autumn 2010) and a further test of feasibility in 191 schools nationally (spring 2011). The four nutrient-specific food-based criteria predicted nutritional adequacy with sensitivity ranging from 0.85 to 1.0, specificity from 0.45 to 1.0 and accuracy from 0.67 to 1.0. The sample in the national study was statistically representative and the majority of users rated the questionnaire positively, suggesting the instrument is feasible. The inter-rater reliability was fair to almost perfect for continuous variables and agreement was ≥ 67 % for categorical variables. An innovative web-based system to comprehensively monitor school meal quality across several domains, with validated questions in the nutritional domain, is available in Sweden for the first time.

8 years of Solar Spectral Irradiance Variability Observed from the ISS with the SOLAR/SOLSPEC Instrument

NASA Astrophysics Data System (ADS)

Damé, Luc; Bolsée, David; Meftah, Mustapha; Irbah, Abdenour; Hauchecorne, Alain; Bekki, Slimane; Pereira, Nuno; Cessateur, Marchand; Gäel; , Marion; et al.

2016-10-01

Accurate measurements of Solar Spectral Irradiance (SSI) are of primary importance for a better understanding of solar physics and of the impact of solar variability on climate (via Earth's atmospheric photochemistry). The acquisition of a top of atmosphere reference solar spectrum and of its temporal and spectral variability during the unusual solar cycle 24 is of prime interest for these studies. These measurements are performed since April 2008 with the SOLSPEC spectro-radiometer from the far ultraviolet to the infrared (166 nm to 3088 nm). This instrument, developed under a fruitful LATMOS/BIRA-IASB collaboration, is part of the Solar Monitoring Observatory (SOLAR) payload, externally mounted on the Columbus module of the International Space Station (ISS). The SOLAR mission, with its actual 8 years duration, will cover almost the entire solar cycle 24. We present here the in-flight operations and performances of the SOLSPEC instrument, including the engineering corrections, calibrations and improved know-how procedure for aging corrections. Accordingly, a SSI reference spectrum from the UV to the NIR will be presented, together with its variability in the UV, as measured by SOLAR/SOLSPEC for 8 years. Uncertainties on these measurements and comparisons with other instruments will be briefly discussed.

Inter-comparison between AIRS and IASI through Retrieved Parameters

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Larar, Allen M.; Smith, William L.; Taylor, Jonathan P.; Schluessel, Peter; Strow, L. Larrabee; Mango, Steve

2008-01-01

A State-of-the-art retrieval algorithm dealing with all-weather conditions has been applied to satellite/aircraft instruments retrieving cloud/surface and atmospheric conditions. High quality retrievals have been achieved from IASI data. Surface, cloud, and atmospheric structure and variation are well captured by IASI measurements and/or retrievals. The same retrieval algorithm is also applied to AIRS for retrieval inter-comparison. Both AIRS and IASI have a similar FOV size but AIRS has a higher horizontal resolution. AIRS data can be interpolated to IASI horizontal resolution for inter-comparison at the same geophysical locations, however a temporal variation between AIRS and IASI observations need to be considered. JAIVEx has employed aircraft to obtain the atmospheric variation filling the temporal gap between two satellites. First results show that both AIRS and IASI have a very similar vertical resolving power, atmospheric conditions are well captured by both instruments, and radiances are well calibrated. AIRS data shown in retrievals (e.g., surface emissivity and moisture) have a relatively higher noise level. Since the this type of retrieval is very sensitive to its radiance quality, retrieval products inter-comparison is an effective way to identify/compare their radiance quality, in terms of a combination of spectral resolution and noise level, and to assess instrument performance. Additional validation analyses are needed to provide more-definitive conclusions.

Inter-track interference mitigation with two-dimensional variable equalizer for bit patterned media recording

NASA Astrophysics Data System (ADS)

Wang, Yao; Vijaya Kumar, B. V. K.

2017-05-01

The increased track density in bit patterned media recording (BPMR) causes increased inter-track interference (ITI), which degrades the bit error rate (BER) performance. In order to mitigate the effect of the ITI, signals from multiple tracks can be equalized by a 2D equalizer with 1D target. Usually, the 2D fixed equalizer coefficients are obtained by using a pseudo-random bit sequence (PRBS) for training. In this study, a 2D variable equalizer is proposed, where various sets of 2D equalizer coefficients are predetermined and stored for different ITI patterns besides the usual PRBS training. For data detection, as the ITI patterns are unknown in the first global iteration, the main and adjacent tracks are equalized with the conventional 2D fixed equalizer, detected with Bahl-Cocke-Jelinek-Raviv (BCJR) detector and decoded with low-density parity-check (LDPC) decoder. Then using the estimated bit information from main and adjacent tracks, the ITI pattern for each island of the main track can be estimated and the corresponding 2D variable equalizers are used to better equalize the bits on the main track. This process is executed iteratively by feeding back the main track information. Simulation results indicate that for both single-track and two-track detection, the proposed 2D variable equalizer can achieve better BER and frame error rate (FER) compared to that with the 2D fixed equalizer.

Sources of Variability in Chlorophyll Analysis by Fluorometry and High-Performance Liquid Chromatography in a SIMBIOS Inter-Calibration Exercise

NASA Technical Reports Server (NTRS)

VanHeukelem, Laurie; Thomas, Crystal S.; Gilbert, Patricia M.; Fargion, Giulietta S. (Editor); McClain, Charles R. (Editor)

2002-01-01

The purpose of this technical report is to provide current documentation of the Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) Project activities, NASA Research Announcement (NRA) research status, satellite data processing, data product validation, and field calibration. This documentation is necessary to ensure that critical information is related to the scientific community and NASA management. This critical information includes the technical difficulties and challenges of validating and combining ocean color data from an array of independent satellite systems to form consistent and accurate global bio-optical time series products. This technical report is not meant as a substitute for scientific literature. Instead, it will provide a ready and responsive vehicle for the multitude of technical reports issued by an operational project. This particular document focus on the variability in chlorophyll pigment measurements resulting from differences in methodologies and laboratories conducting the pigment analysis.

Cesarean delivery rates among family physicians versus obstetricians: a population-based cohort study using instrumental variable methods

PubMed Central

Dawe, Russell Eric; Bishop, Jessica; Pendergast, Amanda; Avery, Susan; Monaghan, Kelly; Duggan, Norah; Aubrey-Bassler, Kris

2017-01-01

Background: Previous research suggests that family physicians have rates of cesarean delivery that are lower than or equivalent to those for obstetricians, but adjustments for risk differences in these analyses may have been inadequate. We used an econometric method to adjust for observed and unobserved factors affecting the risk of cesarean delivery among women attended by family physicians versus obstetricians. Methods: This retrospective population-based cohort study included all Canadian (except Quebec) hospital deliveries by family physicians and obstetricians between Apr. 1, 2006, and Mar. 31, 2009. We excluded women with multiple gestations, and newborns with a birth weight less than 500 g or gestational age less than 20 weeks. We estimated the relative risk of cesarean delivery using instrumental-variable-adjusted and logistic regression. Results: The final cohort included 776 299 women who gave birth in 390 hospitals. The risk of cesarean delivery was 27.3%, and the mean proportion of deliveries by family physicians was 26.9% (standard deviation 23.8%). The relative risk of cesarean delivery for family physicians versus obstetricians was 0.48 (95% confidence interval [CI] 0.41-0.56) with logistic regression and 1.27 (95% CI 1.02-1.57) with instrumental-variable-adjusted regression. Interpretation: Our conventional analyses suggest that family physicians have a lower rate of cesarean delivery than obstetricians, but instrumental variable analyses suggest the opposite. Because instrumental variable methods adjust for unmeasured factors and traditional methods do not, the large discrepancy between these estimates of risk suggests that clinical and/or sociocultural factors affecting the decision to perform cesarean delivery may not be accounted for in our database. PMID:29233843

Job demands and job strain as risk factors for employee wellbeing in elderly care: an instrumental-variables analysis.

PubMed

Elovainio, Marko; Heponiemi, Tarja; Kuusio, Hannamaria; Jokela, Markus; Aalto, Anna-Mari; Pekkarinen, Laura; Noro, Anja; Finne-Soveri, Harriet; Kivimäki, Mika; Sinervo, Timo

2015-02-01

The association between psychosocial work environment and employee wellbeing has repeatedly been shown. However, as environmental evaluations have typically been self-reported, the observed associations may be attributable to reporting bias. Applying instrumental-variable regression, we used staffing level (the ratio of staff to residents) as an unconfounded instrument for self-reported job demands and job strain to predict various indicators of wellbeing (perceived stress, psychological distress and sleeping problems) among 1525 registered nurses, practical nurses and nursing assistants working in elderly care wards. In ordinary regression, higher self-reported job demands and job strain were associated with increased risk of perceived stress, psychological distress and sleeping problems. The effect estimates for the associations of these psychosocial factors with perceived stress and psychological distress were greater, but less precisely estimated, in an instrumental-variables analysis which took into account only the variation in self-reported job demands and job strain that was explained by staffing level. No association between psychosocial factors and sleeping problems was observed with the instrumental-variable analysis. These results support a causal interpretation of high self-reported job demands and job strain being risk factors for employee wellbeing. © The Author 2014. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.

Exploring Differences in Measurement and Reporting of Classroom Observation Inter-Rater Reliability

ERIC Educational Resources Information Center

Wilhelm, Anne Garrison; Gillespie Rouse, Amy; Jones, Francesca

2018-01-01

Although inter-rater reliability is an important aspect of using observational instruments, it has received little theoretical attention. In this article, we offer some guidance for practitioners and consumers of classroom observations so that they can make decisions about inter-rater reliability, both for study design and in the reporting of data…

The Paired Availability Design and Related Instrumental Variable Meta-analyses | Division of Cancer Prevention

Cancer.gov

Stuart G. Baker, 2017 Introduction This software computes meta-analysis and extrapolation estimates for an instrumental variable meta-analysis of randomized trial or before-and-after studies (the latter also known as the paired availability design). The software also checks on the assumptions if sufficient data are available. |

Inter-Rater Variability as Mutual Disagreement: Identifying Raters' Divergent Points of View

ERIC Educational Resources Information Center

Gingerich, Andrea; Ramlo, Susan E.; van der Vleuten, Cees P. M.; Eva, Kevin W.; Regehr, Glenn

2017-01-01

Whenever multiple observers provide ratings, even of the same performance, inter-rater variation is prevalent. The resulting "idiosyncratic rater variance" is considered to be unusable error of measurement in psychometric models and is a threat to the defensibility of our assessments. Prior studies of inter-rater variation in clinical…

Determining the Attitudes of Undergraduate Students Having Vocational Music Education towards Individual Instrument Course According to Different Variables

ERIC Educational Resources Information Center

Uluçay, Taner

2017-01-01

This study was carried out in order to determine attitudes of undergraduate students who studied music vocationally towards the individual instrument course according to the variables of grade, gender, individual instrument and graduated high school type. The research data were obtained from 102 undergraduate students studying in Erzincan…

Secular Change and Inter-annual Variability of the Gulf Stream Position, 1993-2013, 70°-55°W

NASA Astrophysics Data System (ADS)

Bisagni, J. J.; Gangopadhyay, A.

2016-12-01

The Gulf Stream (GS) is the northeastward-flowing surface limb of the Atlantic Ocean meridional overturning circulation (AMOC) "conveyer belt" that flows towards Europe and the Nordic Seas. Changes in the GS position after its separation from the coast at Cape Hatteras, i.e., from 75°W to 50°W, may be key to understanding the AMOC, sea level variability and ecosystem behavior along the east coast of North America. In this study we compare secular change and inter-annual variability (IAV) of annual mean Gulf Stream North Wall (GSNW) position with equator-ward Labrador Current (LC) transport along the southwestern Grand Banks near 52° W using 21 years (1993-2013) of satellite altimeter data. Results at 70°, 65°, 60° and 55° W show a southward secular trend for the GSNW, decreasing to the west. IAV of de-trended GSNW position residuals also decreases to the west. The long-term secular trend of annual mean upper layer LC transport increases near 52° W. Furthermore, IAV of LC transport residuals near 52° W is significantly correlated with GSNW position residuals at 55° W at a lag of +1-year. Spectral analysis reveals inter-annual peaks at 5-7 years and 2-3 years for the North Atlantic Oscillation (NAO), GSNW (65°-55°W) and LC transport for 1993-2013. A volume calculation using the LC rms residual of +1.04 Sv near 52° W results in an estimated GSNW residual of 79 km, or 63% of the observed 125.6 km (1.13°) rms value at 55° W. A similar volume calculation using the positive long-term, upper-layer LC transport trend accounts for 68% of the observed southward shift of the GSNW over the 1993-2013 period. Our work provides observational evidence of direct interaction between the upper layers of the sub-polar and sub-tropical gyres within the North Atlantic over secular and inter-annual time scales as suggested by previous workers.

Airborne hygrometer calibration inter-comparison against a metrological water vapour standard

NASA Astrophysics Data System (ADS)

Smorgon, Denis; Boese, Norbert; Ebert, Volker

2014-05-01

Water vapour is the most important atmospheric greenhouse gas, which causes a major feedback to warming and other changes in the climate system. Knowledge of the distribution of water vapour and its climate induced changes is especially important in the upper troposphere and lower stratosphere (UT/LS) where vapour plays a critical role in atmospheric radiative balance, cirrus cloud formation, and photochemistry. But, our understanding of water in the UT/LS is limited by significant uncertainties in current UT/LS water measurements. One of the most comprehensive inter-comparison campaigns for airborne hygrometers, termed AQUAVIT (AV1) [1], took place in 2007 at the AIDA chamber at the Karlsruhe Institute of Technology (KIT) in Germany. AV1 was a well-defined, referred, blind inter-comparison of 22 airborne field instruments from 17 international research groups. One major metrological deficit of AV1, however, was, that no traceable reference instrument participated in the inter-comparison experiments and that the calibration procedures of the participating instruments were not monitored or interrogated. Consequently a follow-up inter-comparison was organized in April 2013, which for the first time also provides a traceable link to the international humidity scale. This AQUAVIT2 (AV2) campaign (details see: http://www.imk-aaf.kit.edu/aquavit/index.php/Main_Page) was again located at KIT/AIDA and organised by an international organizing committee including KIT, PTB, FZJ and others. Generally AV2 is divided in two parallel comparisons: 1) AV2-A uses the AIDA chamber for a simultaneous comparison of all instruments (incl. sampling and in-situ instruments) over a broad range of conditions characteristic for the UT/LS; 2) AV2-B, about which this paper is reporting, is a sequential comparison of selected hygrometers and (when possible) their reference calibration infrastructures by means of a chilled mirror hygrometer traced back to the primary National humidity standard

The impact of inter-annual variability of annual cycle on long-term persistence of surface air temperature in long historical records

NASA Astrophysics Data System (ADS)

Deng, Qimin; Nian, Da; Fu, Zuntao

2018-02-01

Previous studies in the literature show that the annual cycle of surface air temperature (SAT) is changing in both amplitude and phase, and the SAT departures from the annual cycle are long-term correlated. However, the classical definition of temperature anomalies is based on the assumption that the annual cycle is constant, which contradicts the fact of changing annual cycle. How to quantify the impact of the changing annual cycle on the long-term correlation of temperature anomaly variability still remains open. In this paper, a recently developed data adaptive analysis tool, the nonlinear mode decomposition (NMD), is used to extract and remove time-varying annual cycle to reach the new defined temperature anomalies in which time-dependent amplitude of annual cycle has been considered. By means of detrended fluctuation analysis, the impact induced by inter-annual variability from the time-dependent amplitude of annual cycle has been quantified on the estimation of long-term correlation of long historical temperature anomalies in Europe. The results show that the classical climatology annual cycle is supposed to lack inter-annual fluctuation which will lead to a maximum artificial deviation centering around 600 days. This maximum artificial deviation is crucial to defining the scaling range and estimating the long-term persistence exponent accurately. Selecting different scaling range could lead to an overestimation or underestimation of the long-term persistence exponent. By using NMD method to extract the inter-annual fluctuations of annual cycle, this artificial crossover can be weakened to extend a wider scaling range with fewer uncertainties.

Inter-Labeler and Intra-Labeler Variability of Condition Severity Classification Models Using Active and Passive Learning Methods

PubMed Central

Nissim, Nir; Shahar, Yuval; Boland, Mary Regina; Tatonetti, Nicholas P; Elovici, Yuval; Hripcsak, George; Moskovitch, Robert

2018-01-01

Background and Objectives Labeling instances by domain experts for classification is often time consuming and expensive. To reduce such labeling efforts, we had proposed the application of active learning (AL) methods, introduced our CAESAR-ALE framework for classifying the severity of clinical conditions, and shown its significant reduction of labeling efforts. The use of any of three AL methods (one well known [SVM-Margin], and two that we introduced [Exploitation and Combination_XA]) significantly reduced (by 48% to 64%) condition labeling efforts, compared to standard passive (random instance-selection) SVM learning. Furthermore, our new AL methods achieved maximal accuracy using 12% fewer labeled cases than the SVM-Margin AL method. However, because labelers have varying levels of expertise, a major issue associated with learning methods, and AL methods in particular, is how to best to use the labeling provided by a committee of labelers. First, we wanted to know, based on the labelers’ learning curves, whether using AL methods (versus standard passive learning methods) has an effect on the Intra-labeler variability (within the learning curve of each labeler) and inter-labeler variability (among the learning curves of different labelers). Then, we wanted to examine the effect of learning (either passively or actively) from the labels created by the majority consensus of a group of labelers. Methods We used our CAESAR-ALE framework for classifying the severity of clinical conditions, the three AL methods and the passive learning method, as mentioned above, to induce the classifications models. We used a dataset of 516 clinical conditions and their severity labeling, represented by features aggregated from the medical records of 1.9 million patients treated at Columbia University Medical Center. We analyzed the variance of the classification performance within (intra-labeler), and especially among (inter-labeler) the classification models that were induced by

Inter-labeler and intra-labeler variability of condition severity classification models using active and passive learning methods.

PubMed

Nissim, Nir; Shahar, Yuval; Elovici, Yuval; Hripcsak, George; Moskovitch, Robert

2017-09-01

Labeling instances by domain experts for classification is often time consuming and expensive. To reduce such labeling efforts, we had proposed the application of active learning (AL) methods, introduced our CAESAR-ALE framework for classifying the severity of clinical conditions, and shown its significant reduction of labeling efforts. The use of any of three AL methods (one well known [SVM-Margin], and two that we introduced [Exploitation and Combination_XA]) significantly reduced (by 48% to 64%) condition labeling efforts, compared to standard passive (random instance-selection) SVM learning. Furthermore, our new AL methods achieved maximal accuracy using 12% fewer labeled cases than the SVM-Margin AL method. However, because labelers have varying levels of expertise, a major issue associated with learning methods, and AL methods in particular, is how to best to use the labeling provided by a committee of labelers. First, we wanted to know, based on the labelers' learning curves, whether using AL methods (versus standard passive learning methods) has an effect on the Intra-labeler variability (within the learning curve of each labeler) and inter-labeler variability (among the learning curves of different labelers). Then, we wanted to examine the effect of learning (either passively or actively) from the labels created by the majority consensus of a group of labelers. We used our CAESAR-ALE framework for classifying the severity of clinical conditions, the three AL methods and the passive learning method, as mentioned above, to induce the classifications models. We used a dataset of 516 clinical conditions and their severity labeling, represented by features aggregated from the medical records of 1.9 million patients treated at Columbia University Medical Center. We analyzed the variance of the classification performance within (intra-labeler), and especially among (inter-labeler) the classification models that were induced by using the labels provided by seven

Single-breath diffusing capacity for carbon monoxide instrument accuracy across 3 health systems.

PubMed

Hegewald, Matthew J; Markewitz, Boaz A; Wilson, Emily L; Gallo, Heather M; Jensen, Robert L

2015-03-01

Measuring diffusing capacity of the lung for carbon monoxide (DLCO) is complex and associated with wide intra- and inter-laboratory variability. Increased D(LCO) variability may have important clinical consequences. The objective of the study was to assess instrument performance across hospital pulmonary function testing laboratories using a D(LCO) simulator that produces precise and repeatable D(LCO) values. D(LCO) instruments were tested with CO gas concentrations representing medium and high range D(LCO) values. The absolute difference between observed and target D(LCO) value was used to determine measurement accuracy; accuracy was defined as an average deviation from the target value of < 2.0 mL/min/mm Hg. Accuracy of inspired volume measurement and gas sensors were also determined. Twenty-three instruments were tested across 3 healthcare systems. The mean absolute deviation from the target value was 1.80 mL/min/mm Hg (range 0.24-4.23) with 10 of 23 instruments (43%) being inaccurate. High volume laboratories performed better than low volume laboratories, although the difference was not significant. There was no significant difference among the instruments by manufacturers. Inspired volume was not accurate in 48% of devices; mean absolute deviation from target value was 3.7%. Instrument gas analyzers performed adequately in all instruments. D(LCO) instrument accuracy was unacceptable in 43% of devices. Instrument inaccuracy can be primarily attributed to errors in inspired volume measurement and not gas analyzer performance. D(LCO) instrument performance may be improved by regular testing with a simulator. Caution should be used when comparing D(LCO) results reported from different laboratories. Copyright © 2015 by Daedalus Enterprises.

Development of an audit instrument for nursing care plans in the patient record

PubMed Central

Bjorvell, C; Thorell-Ekstrand, I; Wredling, R

2000-01-01

Objectives—To develop, validate, and test the reliability of an audit instrument that measures the extent to which patient records describe important aspects of nursing care. Material—Twenty records from each of three hospital wards were collected and audited. The auditors were registered nurses with a knowledge of nursing documentation in accordance with the VIPS model—a model designed to structure nursing documentation. (VIPS is an acronym formed from the Swedish words for wellbeing, integrity, prevention, and security.) Methods—An audit instrument was developed by determining specific criteria to be met. The audit questions were aimed at revealing the content of the patient for nursing assessment, nursing diagnosis, planned interventions, and outcome. Each of the 60 records was reviewed by the three auditors independently and the reliability of the instrument was tested by calculating the inter-rater reliability coefficient. Content validity was tested by using an expert panel and calculating the content validity ratio. The criterion related validity was estimated by the correlation between the score of the Cat-ch-Ing instrument and the score of an earlier developed and used audit instrument. The results were then tested by using Pearson's correlation coefficient. Results—The new audit instrument, named Cat-ch-Ing, consists of 17 questions designed to judge the nursing documentation. Both quantity and quality variables are judged on a rating scale from zero to three, with a maximum score of 80. The inter-rater reliability coefficients were 0.98, 0.98, and 0.92, respectively for each group of 20 records, the content validity ratio ranged between 0.20 and 1.0 and the criterion related validity showed a significant correlation of r = 0.68 (p< 0.0001, 95% CI 0.57 to 0.76) between the two audit instruments. Conclusion—The Cat-ch-Ing instrument has proved to be a valid and reliable audit instrument for nursing records when the VIPS model is used as the

Inter-laboratory validation of bioaccessibility testing for metals.

PubMed

Henderson, Rayetta G; Verougstraete, Violaine; Anderson, Kim; Arbildua, José J; Brock, Thomas O; Brouwers, Tony; Cappellini, Danielle; Delbeke, Katrien; Herting, Gunilla; Hixon, Greg; Odnevall Wallinder, Inger; Rodriguez, Patricio H; Van Assche, Frank; Wilrich, Peter; Oller, Adriana R

2014-10-01

Bioelution assays are fast, simple alternatives to in vivo testing. In this study, the intra- and inter-laboratory variability in bioaccessibility data generated by bioelution tests were evaluated in synthetic fluids relevant to oral, inhalation, and dermal exposure. Using one defined protocol, five laboratories measured metal release from cobalt oxide, cobalt powder, copper concentrate, Inconel alloy, leaded brass alloy, and nickel sulfate hexahydrate. Standard deviations of repeatability (sr) and reproducibility (sR) were used to evaluate the intra- and inter-laboratory variability, respectively. Examination of the sR:sr ratios demonstrated that, while gastric and lysosomal fluids had reasonably good reproducibility, other fluids did not show as good concordance between laboratories. Relative standard deviation (RSD) analysis showed more favorable reproducibility outcomes for some data sets; overall results varied more between- than within-laboratories. RSD analysis of sr showed good within-laboratory variability for all conditions except some metals in interstitial fluid. In general, these findings indicate that absolute bioaccessibility results in some biological fluids may vary between different laboratories. However, for most applications, measures of relative bioaccessibility are needed, diminishing the requirement for high inter-laboratory reproducibility in absolute metal releases. The inter-laboratory exercise suggests that the degrees of freedom within the protocol need to be addressed. Copyright © 2014 Elsevier Inc. All rights reserved.

Factors Affecting the Inter-annual to Centennial Time Scale Variability of All Indian Summer Monsoon Rainfall

NASA Astrophysics Data System (ADS)

Malik, Abdul; Brönnimann, Stefan

2016-04-01

The All Indian Summer Monsoon Rainfall (AISMR) is highly important for the livelihood of more than 1 billion people living in the Indian sub-continent. The agriculture of this region is heavily dependent on seasonal (JJAS) monsoon rainfall. An early start or a slight delay of monsoon, or an early withdrawal or prolonged monsoon season may upset the farmer's agricultural plans, can cause significant reduction in crop yield, and hence economic loss. Understanding of AISMR is also vital because it is a part of global atmospheric circulation system. Several studies show that AISMR is influenced by internal climate forcings (ICFs) viz. ENSO, AMO, PDO etc. as well as external climate forcings (ECFs) viz. Greenhouse Gases, volcanic eruptions, and Total Solar Irradiance (TSI). We investigate the influence of ICFs and ECFs on AISMR using recently developed statistical technique called De-trended Partial-Cross-Correlation Analysis (DPCCA). DPCCA can analyse a complex system of several interlinked variables. Often, climatic variables, being cross correlated, are simultaneously tele-connected with several other variables and it is not easy to isolate their intrinsic relationship. In the presence of non-stationarities and background signals the calculated correlation coefficients can be overestimated and erroneous. DPCCA method removes the non-stationarities and partials out the influence of background signals from the variables being cross correlated and thus give a robust estimate of correlation. We have performed the analysis using NOAA Reconstructed SSTs and homogenised instrumental AISMR data set from 1854-1999. By employing the DPCCA method we find that there is a statistically insignificant negative intrinsic relation (by excluding the influence of ICFs, and ECFs except TSI) between AISMR and TSI on decadal to centennial time scale. The ICFs considerably modulate the relation between AISMR and solar activity between 50-80 year time scales and transform this relationship

Intra-seasonal and Inter-annual variability of Bowen Ratio over rain-shadow region of North peninsular India

NASA Astrophysics Data System (ADS)

Morwal, S. B.; Narkhedkar, S. G.; Padmakumari, B.; Maheskumar, R. S.; Deshpande, C. G.; Kulkarni, J. R.

2017-05-01

Intra-seasonal and inter-annual variability of Bowen Ratio (BR) have been studied over the rain-shadow region of north peninsular India during summer monsoon season. Daily grid point data of latent heat flux (LHF), sensible heat flux (SHF) from NCEP/NCAR Reanalysis for the period 1970-2014 have been used to compute daily area-mean BR. Daily grid point rainfall data at a resolution of 0.25° × 0.25° from APHRODITE's Water Resources for the available period 1970-2007 have been used to study the association between rainfall and BR. The study revealed that BR rapidly decreases from 4.1 to 0.29 in the month of June and then remains nearly constant at the same value (≤0.1) in the rest of the season. High values of BR in the first half of June are indicative of intense thermals and convective clouds with higher bases. Low values of BR from July to September period are indicative of weak thermals and convective clouds with lower bases. Intra-seasonal and inter-annual variability of BR is found to be inversely related to precipitation over the region. BR analysis indicates that the land surface characteristics of the study region during July-September are similar to that over oceanic regions as far as intensity of thermals and associated cloud microphysical properties are concerned. Similar variation of BR is found in El Nino and La Nina years. During June, an increasing trend is observed in SHF and BR and decreasing trend in LHF from 1976 to 2014. Increasing trend in the SHF is statistically significant.

Comparison of variance estimators for meta-analysis of instrumental variable estimates

PubMed Central

Schmidt, AF; Hingorani, AD; Jefferis, BJ; White, J; Groenwold, RHH; Dudbridge, F

2016-01-01

Abstract Background: Mendelian randomization studies perform instrumental variable (IV) analysis using genetic IVs. Results of individual Mendelian randomization studies can be pooled through meta-analysis. We explored how different variance estimators influence the meta-analysed IV estimate. Methods: Two versions of the delta method (IV before or after pooling), four bootstrap estimators, a jack-knife estimator and a heteroscedasticity-consistent (HC) variance estimator were compared using simulation. Two types of meta-analyses were compared, a two-stage meta-analysis pooling results, and a one-stage meta-analysis pooling datasets. Results: Using a two-stage meta-analysis, coverage of the point estimate using bootstrapped estimators deviated from nominal levels at weak instrument settings and/or outcome probabilities ≤ 0.10. The jack-knife estimator was the least biased resampling method, the HC estimator often failed at outcome probabilities ≤ 0.50 and overall the delta method estimators were the least biased. In the presence of between-study heterogeneity, the delta method before meta-analysis performed best. Using a one-stage meta-analysis all methods performed equally well and better than two-stage meta-analysis of greater or equal size. Conclusions: In the presence of between-study heterogeneity, two-stage meta-analyses should preferentially use the delta method before meta-analysis. Weak instrument bias can be reduced by performing a one-stage meta-analysis. PMID:27591262

An improved estimator for the hydration of fat-free mass from in vivo measurements subject to additive technical errors.

PubMed

Kinnamon, Daniel D; Lipsitz, Stuart R; Ludwig, David A; Lipshultz, Steven E; Miller, Tracie L

2010-04-01

The hydration of fat-free mass, or hydration fraction (HF), is often defined as a constant body composition parameter in a two-compartment model and then estimated from in vivo measurements. We showed that the widely used estimator for the HF parameter in this model, the mean of the ratios of measured total body water (TBW) to fat-free mass (FFM) in individual subjects, can be inaccurate in the presence of additive technical errors. We then proposed a new instrumental variables estimator that accurately estimates the HF parameter in the presence of such errors. In Monte Carlo simulations, the mean of the ratios of TBW to FFM was an inaccurate estimator of the HF parameter, and inferences based on it had actual type I error rates more than 13 times the nominal 0.05 level under certain conditions. The instrumental variables estimator was accurate and maintained an actual type I error rate close to the nominal level in all simulations. When estimating and performing inference on the HF parameter, the proposed instrumental variables estimator should yield accurate estimates and correct inferences in the presence of additive technical errors, but the mean of the ratios of TBW to FFM in individual subjects may not.

Inter-worker variability in lower body postures during assembly line work: implications for exposure assessment.

PubMed

Keyserling, W Monroe; Wiggermann, Neal; Werner, Robert A; Gell, Nancy

2010-05-01

This study evaluated inter-worker variability in lower body posture and work activity during highly-structured assembly line work. Data were collected from 79 unique assembly line workstations in an engine manufacturing plant. Because the plant utilized work teams, 4-8 workers rotated through each workstation. At least 30 min of videotape was collected from at least three workers at each workstation. A computer-assisted work sampling procedure randomly selected 200 video "freeze-frames" for each worker. Lower body posture/movement (e.g., sit, stand, walk, etc.) was determined for each frame and used to estimate the percentage of time the worker spent in various postures and activities. Chi-square analyses were performed for each workstation to assess the significance of inter-worker differences. Due to variations in individual work methods, significant differences (p <.05) were found at 57 out of 79 workstations (72%). The greatest differences occurred when workers had the option to choose between standing and sitting (significant in 8 of 8 cases; in extreme examples, sit time ranged between 0-100% on one job, and 6.5-98% on another). Studying a single worker (or "proxy") can contribute to substantial error when estimating exposures in workplace studies of ergonomic stressors, since the proxy may not be representative of all workers who perform the job. Individual measurements are preferable, particularly for jobs where workers have substantial latitude to develop individualized work methods.

Comparison of Inter-Observer Variability and Diagnostic Performance of the Fifth Edition of BI-RADS for Breast Ultrasound of Static versus Video Images.

PubMed

Youk, Ji Hyun; Jung, Inkyung; Yoon, Jung Hyun; Kim, Sung Hun; Kim, You Me; Lee, Eun Hye; Jeong, Sun Hye; Kim, Min Jung

2016-09-01

Our aim was to compare the inter-observer variability and diagnostic performance of the Breast Imaging Reporting and Data System (BI-RADS) lexicon for breast ultrasound of static and video images. Ninety-nine breast masses visible on ultrasound examination from 95 women 19-81 y of age at five institutions were enrolled in this study. They were scheduled to undergo biopsy or surgery or had been stable for at least 2 y of ultrasound follow-up after benign biopsy results or typically benign findings. For each mass, representative long- and short-axis static ultrasound images were acquired; real-time long- and short-axis B-mode video images through the mass area were separately saved as cine clips. Each image was reviewed independently by five radiologists who were asked to classify ultrasound features according to the fifth edition of the BI-RADS lexicon. Inter-observer variability was assessed using kappa (κ) statistics. Diagnostic performance on static and video images was compared using the area under the receiver operating characteristic curve. No significant difference was found in κ values between static and video images for all descriptors, although κ values of video images were higher than those of static images for shape, orientation, margin and calcifications. After receiver operating characteristic curve analysis, the video images (0.83, range: 0.77-0.87) had higher areas under the curve than the static images (0.80, range: 0.75-0.83; p = 0.08). Inter-observer variability and diagnostic performance of video images was similar to that of static images on breast ultrasonography according to the new edition of BI-RADS. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Inter-subject variability of muscle synergies during bench press in power lifters and untrained individuals.

PubMed

Kristiansen, M; Madeleine, P; Hansen, E A; Samani, A

2015-02-01

The purpose of the study was to elucidate the role of expertise on muscle synergies involved in bench press. Ten expert power lifters (EXP) and nine untrained participants (UNT) completed three sets of eight repetitions at 60% of three repetition maximum in bench press. Muscle synergies were extracted from surface electromyography data of 21 bench press cycles using non-negative matrix factorization algorithm. The synergy activation coefficient represents the relative contribution of the muscle synergy to the overall muscle activity pattern, while the muscle synergy vector represents the relative weighting of each muscle within each synergy. Describing more than 90% of the variability, two muscle synergies reflected the eccentric and concentric phase. The cross-correlations (ρ(max)) for synergy activation coefficient 2 (concentric phase) were 0.83 [0.71;0.88] and 0.59 [0.49;0.77] [Median ρ(max) (25th;75th percentile)] (P = 0.001) in UNT and EXP, respectively. Median correlation coefficient (ρ) for muscle synergy vector 2 was 0.15 [-0.08;0.46] and 0.48 [0.02;0.70] (P = 0.03) in UNT and EXP, respectively. Thus, EXP showed larger inter-subject variability than UNT in the synergy activation coefficient during the concentric phase, while the muscle synergy vectors were less variable in EXP. This points at the importance of a specialized neural strategy in elite bench press performance. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Book Order/Inter Library Loan Documentation

DTIC Science & Technology

1992-04-20

BORROWER: SCOTT DAVID OFFICE: DPRA ARTICLE TITLE: LABORATORY STUDY OF THE RELEASE OF PESTICIDES AND PCB MATERIALS TO THE WATER COLUMN DURING... ARTICLE...TECHNICAL INFORMATION CENTER PAGE NO. INTER LIBARY LOAN REPORT BORROWER: SCOTT DAVID OFFICE: DPRA ARTICLE TITLE: LABORATORY STUDY OF THE RELEASE OF...FROM A USER THAT REQUIRES FEWER THAN 15 MINUTES OF A STAFF MEMBER’S TIME TO ANSWER. MAY INCLUDE A RTIC CATALOG SEARCH, VERIFICATION OF INFORMATION IN A

Analytical techniques and instrumentation: A compilation

NASA Technical Reports Server (NTRS)

1974-01-01

Technical information on developments in instrumentation is arranged into four sections: (1) instrumentation for analysis; (2) analysis of matter; (3) analysis of electrical and mechanical phenomena; and (4) structural analysis. Patent information for two of the instruments described is presented.

Comparison and covalidation of ozone anomalies and variability observed in SBUV(/2) and Umkehr northern midlatitude ozone profile estimates

NASA Astrophysics Data System (ADS)

Petropavlovskikh, I.; Ahn, Changwoo; Bhartia, P. K.; Flynn, L. E.

2005-03-01

This analysis presents comparisons of upper-stratosphere ozone information observed by two independent systems: the Solar Backscatter UltraViolet (SBUV and SBUV/2) satellite instruments, and ground-based Dobson spectrophotometers. Both the new SBUV Version 8 and the new UMK04 profile retrieval algorithms are optimized for studying long-term variability and trends in ozone. Trend analyses of the ozone time series from the SBUV(/2) data set are complex because of the multiple instruments involved, changes in the instruments' geo-location, and short periods of overlaps for inter-calibrations among different instruments. Three northern middle latitudes Dobson ground stations (Arosa, Boulder, and Tateno) are used in this analysis to validate the trend quality of the combined 25-year SBUV/2 time series, 1979 to 2003. Generally, differences between the satellite and ground-based data do not suggest any significant time-dependent shifts or trends. The shared features confirm the value of these data sets for studies of ozone variability.

Regression calibration for models with two predictor variables measured with error and their interaction, using instrumental variables and longitudinal data.

PubMed

Strand, Matthew; Sillau, Stefan; Grunwald, Gary K; Rabinovitch, Nathan

2014-02-10

Regression calibration provides a way to obtain unbiased estimators of fixed effects in regression models when one or more predictors are measured with error. Recent development of measurement error methods has focused on models that include interaction terms between measured-with-error predictors, and separately, methods for estimation in models that account for correlated data. In this work, we derive explicit and novel forms of regression calibration estimators and associated asymptotic variances for longitudinal models that include interaction terms, when data from instrumental and unbiased surrogate variables are available but not the actual predictors of interest. The longitudinal data are fit using linear mixed models that contain random intercepts and account for serial correlation and unequally spaced observations. The motivating application involves a longitudinal study of exposure to two pollutants (predictors) - outdoor fine particulate matter and cigarette smoke - and their association in interactive form with levels of a biomarker of inflammation, leukotriene E4 (LTE 4 , outcome) in asthmatic children. Because the exposure concentrations could not be directly observed, we used measurements from a fixed outdoor monitor and urinary cotinine concentrations as instrumental variables, and we used concentrations of fine ambient particulate matter and cigarette smoke measured with error by personal monitors as unbiased surrogate variables. We applied the derived regression calibration methods to estimate coefficients of the unobserved predictors and their interaction, allowing for direct comparison of toxicity of the different pollutants. We used simulations to verify accuracy of inferential methods based on asymptotic theory. Copyright © 2013 John Wiley & Sons, Ltd.

Physical fitness predicts technical-tactical and time-motion profile in simulated Judo and Brazilian Jiu-Jitsu matches.

PubMed

Coswig, Victor S; Gentil, Paulo; Bueno, João C A; Follmer, Bruno; Marques, Vitor A; Del Vecchio, Fabrício B

2018-01-01

Among combat sports, Judo and Brazilian Jiu-Jitsu (BJJ) present elevated physical fitness demands from the high-intensity intermittent efforts. However, information regarding how metabolic and neuromuscular physical fitness is associated with technical-tactical performance in Judo and BJJ fights is not available. This study aimed to relate indicators of physical fitness with combat performance variables in Judo and BJJ. The sample consisted of Judo ( n  = 16) and BJJ ( n  = 24) male athletes. At the first meeting, the physical tests were applied and, in the second, simulated fights were performed for later notational analysis. The main findings indicate: (i) high reproducibility of the proposed instrument and protocol used for notational analysis in a mobile device; (ii) differences in the technical-tactical and time-motion patterns between modalities; (iii) performance-related variables are different in Judo and BJJ; and (iv) regression models based on metabolic fitness variables may account for up to 53% of the variances in technical-tactical and/or time-motion variables in Judo and up to 31% in BJJ, whereas neuromuscular fitness models can reach values up to 44 and 73% of prediction in Judo and BJJ, respectively. When all components are combined, they can explain up to 90% of high intensity actions in Judo. In conclusion, performance prediction models in simulated combat indicate that anaerobic, aerobic and neuromuscular fitness variables contribute to explain time-motion variables associated with high intensity and technical-tactical variables in Judo and BJJ fights.

Evaluating disease management programme effectiveness: an introduction to instrumental variables.

PubMed

Linden, Ariel; Adams, John L

2006-04-01

This paper introduces the concept of instrumental variables (IVs) as a means of providing an unbiased estimate of treatment effects in evaluating disease management (DM) programme effectiveness. Model development is described using zip codes as the IV. Three diabetes DM outcomes were evaluated: annual diabetes costs, emergency department (ED) visits and hospital days. Both ordinary least squares (OLS) and IV estimates showed a significant treatment effect for diabetes costs (P = 0.011) but neither model produced a significant treatment effect for ED visits. However, the IV estimate showed a significant treatment effect for hospital days (P = 0.006) whereas the OLS model did not. These results illustrate the utility of IV estimation when the OLS model is sensitive to the confounding effect of hidden bias.

Effects of modified Pilates on variability of inter-joint coordination during walking in the elderly

PubMed Central

Roh, SuYeon; Yoon, Sukhoon; Kim, Joo Nyeon; Lim, Hee Sung

2016-01-01

[Purpose] This study aimed to examine the effects of an 8-week modified Pilates program on the variability of inter-joint coordination in the elderly during walking. [Subjects and Methods] Twenty elderly participants with no recent history of orthopedic abnormalities (age, 67.9 ± 2.7 years; height, 163.7 ± 8.9 cm; weight, 67.1 ± 11.6 kg) were recruited for this study and randomly allocated to a modified Pilates exercise group or a control group. Three-dimensional motion analysis was performed on both groups to evaluate the effects of the Pilates exercise. [Results] There was no significant difference in the joint variability of the ankle, knee, and hip joints between the groups, both before training and after training. However, there was a significant increase in the hip-knee deviation phase value in the exercise group after the program was completed, and this increase was also significant when compared with that in the control group. [Conclusion] This study has demonstrated that an 8-week modified Pilates exercise program can have a positive impact on the gait of elderly participants, potentially by enhancing neuromuscular adjustment, which may have positive implications for reducing their fall risk. PMID:28174474

Effects of modified Pilates on variability of inter-joint coordination during walking in the elderly.

PubMed

Yoon, Sukhoon; Kim, Joo Nyeon; Lim, Hee Sung

2016-12-01

[Purpose] This study aimed to examine the effects of an 8-week modified Pilates program on the variability of inter-joint coordination in the elderly during walking. [Subjects and Methods] Twenty elderly participants with no recent history of orthopedic abnormalities (age, 67.9 ± 2.7 years; height, 163.7 ± 8.9 cm; weight, 67.1 ± 11.6 kg) were recruited for this study and randomly allocated to a modified Pilates exercise group or a control group. Three-dimensional motion analysis was performed on both groups to evaluate the effects of the Pilates exercise. [Results] There was no significant difference in the joint variability of the ankle, knee, and hip joints between the groups, both before training and after training. However, there was a significant increase in the hip-knee deviation phase value in the exercise group after the program was completed, and this increase was also significant when compared with that in the control group. [Conclusion] This study has demonstrated that an 8-week modified Pilates exercise program can have a positive impact on the gait of elderly participants, potentially by enhancing neuromuscular adjustment, which may have positive implications for reducing their fall risk.

Non-technical skills assessment for prelicensure nursing students: An integrative review.

PubMed

Pires, Sara; Monteiro, Sara; Pereira, Anabela; Chaló, Daniela; Melo, Elsa; Rodrigues, Alexandre

2017-11-01

In nursing, non-technical skills are recognized as playing an important role to increase patient safety and successful clinical outcomes (Pearson and McLafferty, 2011). Non-technical skills are cognitive and social resource skills that complement technical skills and contribute to safe and efficient task performance (Flin et al., 2008). In order to effectively provide non-technical skills training, it is essential to have an instrument to measure these skills. An online search was conducted. Articles were selected if they referred to and/or described instruments assessing non-technical skills for nurses and/or prelicensure nursing students in educational, clinical and/or simulated settings with validation evidence (inclusion criteria). Of the 53 articles located, 26 met the inclusion criteria. Those referred to and/or described 16 instruments with validation evidence developed to assess non-technical skills in multidisciplinary teams including nurses. Although articles have shown 16 valid and reliable instruments, to our knowledge, no instrument has been published or developed and validated for the assessment of non-technical skills of only nurses in general, relevant for use in high-fidelity simulation-based training for prelicensure nursing students. Therefore, there is a need for the development of such an instrument. Copyright © 2017 Elsevier Ltd. All rights reserved.

Inter- and Intra-method Variability of VS Profiles and VS30 at ARRA-funded Sites

NASA Astrophysics Data System (ADS)

Yong, A.; Boatwright, J.; Martin, A. J.

2015-12-01

The 2009 American Recovery and Reinvestment Act (ARRA) funded geophysical site characterizations at 191 seismographic stations in California and in the central and eastern United States. Shallow boreholes were considered cost- and environmentally-prohibitive, thus non-invasive methods (passive and active surface- and body-wave techniques) were used at these stations. The drawback, however, is that these techniques measure seismic properties indirectly and introduce more uncertainty than borehole methods. The principal methods applied were Array Microtremor (AM), Multi-channel Analysis of Surface Waves (MASW; Rayleigh and Love waves), Spectral Analysis of Surface Waves (SASW), Refraction Microtremor (ReMi), and P- and S-wave refraction tomography. Depending on the apparent geologic or seismic complexity of the site, field crews applied one or a combination of these methods to estimate the shear-wave velocity (VS) profile and calculate VS30, the time-averaged VS to a depth of 30 meters. We study the inter- and intra-method variability of VS and VS30 at each seismographic station where combinations of techniques were applied. For each site, we find both types of variability in VS30 remain insignificant (5-10% difference) despite substantial variability observed in the VS profiles. We also find that reliable VS profiles are best developed using a combination of techniques, e.g., surface-wave VS profiles correlated against P-wave tomography to constrain variables (Poisson's ratio and density) that are key depth-dependent parameters used in modeling VS profiles. The most reliable results are based on surface- or body-wave profiles correlated against independent observations such as material properties inferred from outcropping geology nearby. For example, mapped geology describes station CI.LJR as a hard rock site (VS30 > 760 m/s). However, decomposed rock outcrops were found nearby and support the estimated VS30 of 303 m/s derived from the MASW (Love wave) profile.

QNOTE: an instrument for measuring the quality of EHR clinical notes.

PubMed

Burke, Harry B; Hoang, Albert; Becher, Dorothy; Fontelo, Paul; Liu, Fang; Stephens, Mark; Pangaro, Louis N; Sessums, Laura L; O'Malley, Patrick; Baxi, Nancy S; Bunt, Christopher W; Capaldi, Vincent F; Chen, Julie M; Cooper, Barbara A; Djuric, David A; Hodge, Joshua A; Kane, Shawn; Magee, Charles; Makary, Zizette R; Mallory, Renee M; Miller, Thomas; Saperstein, Adam; Servey, Jessica; Gimbel, Ronald W

2014-01-01

The outpatient clinical note documents the clinician's information collection, problem assessment, and patient management, yet there is currently no validated instrument to measure the quality of the electronic clinical note. This study evaluated the validity of the QNOTE instrument, which assesses 12 elements in the clinical note, for measuring the quality of clinical notes. It also compared its performance with a global instrument that assesses the clinical note as a whole. Retrospective multicenter blinded study of the clinical notes of 100 outpatients with type 2 diabetes mellitus who had been seen in clinic on at least three occasions. The 300 notes were rated by eight general internal medicine and eight family medicine practicing physicians. The QNOTE instrument scored the quality of the note as the sum of a set of 12 note element scores, and its inter-rater agreement was measured by the intraclass correlation coefficient. The Global instrument scored the note in its entirety, and its inter-rater agreement was measured by the Fleiss κ. The overall QNOTE inter-rater agreement was 0.82 (CI 0.80 to 0.84), and its note quality score was 65 (CI 64 to 66). The Global inter-rater agreement was 0.24 (CI 0.19 to 0.29), and its note quality score was 52 (CI 49 to 55). The QNOTE quality scores were consistent, and the overall QNOTE score was significantly higher than the overall Global score (p=0.04). We found the QNOTE to be a valid instrument for evaluating the quality of electronic clinical notes, and its performance was superior to that of the Global instrument. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Modelling Inter-relationships among water, governance, human development variables in developing countries with Bayesian networks.

NASA Astrophysics Data System (ADS)

Dondeynaz, C.; Lopez-Puga, J.; Carmona-Moreno, C.

2012-04-01

Improving Water and Sanitation Services (WSS), being a complex and interdisciplinary issue, passes through collaboration and coordination of different sectors (environment, health, economic activities, governance, and international cooperation). This inter-dependency has been recognised with the adoption of the "Integrated Water Resources Management" principles that push for the integration of these various dimensions involved in WSS delivery to ensure an efficient and sustainable management. The understanding of these interrelations appears as crucial for decision makers in the water sector in particular in developing countries where WSS still represent an important leverage for livelihood improvement. In this framework, the Joint Research Centre of the European Commission has developed a coherent database (WatSan4Dev database) containing 29 indicators from environmental, socio-economic, governance and financial aid flows data focusing on developing countries (Celine et al, 2011 under publication). The aim of this work is to model the WatSan4Dev dataset using probabilistic models to identify the key variables influencing or being influenced by the water supply and sanitation access levels. Bayesian Network Models are suitable to map the conditional dependencies between variables and also allows ordering variables by level of influence on the dependent variable. Separated models have been built for water supply and for sanitation because of different behaviour. The models are validated if complying with statistical criteria but either with scientific knowledge and literature. A two steps approach has been adopted to build the structure of the model; Bayesian network is first built for each thematic cluster of variables (e.g governance, agricultural pressure, or human development) keeping a detailed level for interpretation later one. A global model is then built based on significant indicators of each cluster being previously modelled. The structure of the

Evidence for inter- and intraspecies biofilm formation variability among a small group of coagulase-negative staphylococci.

PubMed

Oliveira, Fernando; Lima, Cláudia Afonso; Brás, Susana; França, Ângela; Cerca, Nuno

2015-10-01

Coagulase-negative staphylococci (CoNS) are common bacterial colonizers of the human skin. They are often involved in nosocomial infections due to biofilm formation in indwelling medical devices. While biofilm formation has been extensively studied in Staphylococcus epidermidis, little is known regarding other CoNS species. Here, biofilms from six different CoNS species were characterized in terms of biofilm composition and architecture. Interestingly, the ability to form a thick biofilm was not associated with any particular species, and high variability on biofilm accumulation was found within the same species. Cell viability assays also revealed different proportions of live and dead cells within biofilms formed by different species, although this parameter was particularly similar at the intraspecies level. On the other hand, biofilm disruption assays demonstrated important inter- and intraspecies differences regarding extracellular matrix composition. Lastly, confocal laser scanning microscopy experiments confirmed this variability, highlighting important differences and common features of CoNS biofilms. We hypothesized that the biofilm formation heterogeneity observed was rather associated with biofilm matrix composition than with cells themselves. Additionally, our results indicate that polysaccharides, DNA and proteins are fundamental pieces in the process of CoNS biofilm formation. © FEMS 2015. All rights reserved.

Aiming for excellence - A simulation-based study on adapting and testing an instrument for developing non-technical skills in Norwegian student nurse anaesthetists.

PubMed

Flynn, Fiona M; Sandaker, Kjersti; Ballangrud, Randi

2017-01-01

There is increasing focus on building safety into anaesthesia practice, with excellence in anaesthesia as an aspirational goal. Non-technical skills are an important factor in excellence and improved patient safety, though there have been few systematic attempts at integrating them into anaesthesia nursing education. This study aimed to test the reliability of NANTS-no, a specially adapted behavioural marker system for nurse anaesthetists in Norway, and explore the development of non-technical skills in student nurse anaesthetists. The pre-test post-test design incorporated a 10-week simulation-based programme, where non-technical skills in 14 student nurse anaesthetists were rated on three different occasions during high-fidelity simulation, before and after taking part in a training course. NANTS-no demonstrated high overall inter-rater reliability (ICC = 0.91), high test-retest reliability (ICC = 0.94) and good internal consistency (Cronbach's α of 0.85-0.92). A significant improvement was demonstrated across all categories of non-technical skills, with greatest improvements between the first and third and second and third sessions. There was also a significant improvement in two categories between the first and second sessions. NANTS-no is therefore suitable for assessing non-technical skills during simulation training in anaesthesia nursing education. More research is needed to validate its use in clinical practice. Copyright © 2016 Elsevier Ltd. All rights reserved.

Technical Stability and Biological Variability in MicroRNAs from Dried Blood Spots: A Lung Cancer Therapy-Monitoring Showcase.

PubMed

Kahraman, Mustafa; Laufer, Thomas; Backes, Christina; Schrörs, Hannah; Fehlmann, Tobias; Ludwig, Nicole; Kohlhaas, Jochen; Meese, Eckart; Wehler, Thomas; Bals, Robert; Keller, Andreas

2017-09-01

Different work flows have been proposed to use miRNAs as blood-borne biomarkers. In particular, the method used for collecting blood from patients can considerably influence the diagnostic results. We explored whether dried blood spots (DBSs) facilitate stable miRNA measurements and compared its technical stability with biological variability. First, we tested the stability of DBS samples by generating from 1 person 18 whole-genome-wide miRNA profiles of DBS samples that were exposed to different temperature and humidity conditions. Second, we investigated technical reproducibility by performing 7 replicates of DBS again from 1 person. Third, we investigated DBS samples from 53 patients with lung cancer undergoing different therapies. Across these 3 stages, 108 genome-wide miRNA profiles from DBS were generated and evaluated biostatistically. In the stability analysis, we observed that temperature and humidity had an overall limited influence on the miRNomes (average correlation between the different conditions of 0.993). Usage of a silica gel slightly diminished DBS' technical reproducibility. The 7 technical replicates had an average correlation of 0.996. The correlation with whole-blood PAXGene miRNomes of the same individual was remarkable (correlation of 0.88). Finally, evaluation of the samples from the 53 patients with lung cancer exposed to different therapies showed that the biological variations exceeded the technical variability significantly ( P < 0.0001), yielding 51 dysregulated miRNAs. We present a stable work flow for profiling of whole miRNomes on the basis of samples collected from DBS. Biological variations exceeded technical variations significantly. DBS-based miRNA profiles will potentially further the translational character of miRNA biomarker studies. © 2017 American Association for Clinical Chemistry.

The effect of inter-annual variability of consumption, production, trade and climate on crop-related green and blue water footprints and inter-regional virtual water trade: A study for China (1978-2008).

PubMed

Zhuo, La; Mekonnen, Mesfin M; Hoekstra, Arjen Y

2016-05-01

Previous studies into the relation between human consumption and indirect water resources use have unveiled the remote connections in virtual water (VW) trade networks, which show how communities externalize their water footprint (WF) to places far beyond their own region, but little has been done to understand variability in time. This study quantifies the effect of inter-annual variability of consumption, production, trade and climate on WF and VW trade, using China over the period 1978-2008 as a case study. Evapotranspiration, crop yields and green and blue WFs of crops are estimated at a 5 × 5 arc-minute resolution for 22 crops, for each year in the study period, thus accounting for climate variability. The results show that crop yield improvements during the study period helped to reduce the national average WF of crop consumption per capita by 23%, with a decreasing contribution to the total from cereals and increasing contribution from oil crops. The total consumptive WFs of national crop consumption and crop production, however, grew by 6% and 7%, respectively. By 2008, 28% of total water consumption in crop fields in China served the production of crops for export to other regions and, on average, 35% of the crop-related WF of a Chinese consumer was outside its own province. Historically, the net VW within China was from the water-rich South to the water-scarce North, but intensifying North-to-South crop trade reversed the net VW flow since 2000, which amounted 6% of North's WF of crop production in 2008. South China thus gradually became dependent on food supply from the water-scarce North. Besides, during the whole study period, China's domestic inter-regional VW flows went dominantly from areas with a relatively large to areas with a relatively small blue WF per unit of crop, which in 2008 resulted in a trade-related blue water loss of 7% of the national total blue WF of crop production. The case of China shows that domestic trade, as governed by

Career Technical Education Adjunct Faculty Teacher Readiness: An Investigation of Teacher Excellence and Variables of Preparedness

ERIC Educational Resources Information Center

Guerra, Jorge

2012-01-01

The purpose of this research was to examine the relationship between teaching readiness and teaching excellence with three variables of preparedness of adjunct professors teaching career technical education courses through student surveys using a correlational design of two statistical techniques; least-squares regression and one-way analysis of…

Inter- and intra-observer variability of radiography and computed tomography for evaluation of Zurich cementless acetabular cup placement ex vivo.

PubMed

Leasure, Jessica O; Peck, Jeffrey N; Villamil, Armando; Fiore, Kara L; Tano, Cheryl A

2016-11-23

To evaluate the inter- and intra-observer variability in measurement of the angle of lateral opening (ALO) and version angle measurement using digital radiography and computed tomography (CT). Each hemipelvis was implanted with a cementless acetabular cup. Ventrodorsal and mediolateral radiographs were made of each pelvis, followed by CT imaging. After removal of the first cup, the pelves were implanted with an acetabular cup in the contralateral acetabulum and imaging was repeated. Three surgeons measured the ALO and version angles three times for each cup from the mediolateral radiographic projection. The same measurements were made using three-dimensional multiplanar reconstructions from CT images. Two anatomical axes were used to measure pelvic inclination in the sagittal plane, resulting in six measurements per cup. Two-way repeated measures analysis of variance evaluated inter- and intra-observer repeatability for radiographic and CT-based measurements. Version angle based on radiographic measurement did not differ within surgeons (p = 0.433), but differed between surgeons (p <0.001). Radiographic measurement of ALO differed within surgeons (p = 0.006) but not between surgeons (p = 0.989). The ALO and version angle measured on CT images did not differ with or between surgeons. Assessment of inter- and intra-observer measurement of ALO and version angle was more reproducible using CT images than conventional mediolateral radiography for a Zurich cementless acetabular cup.

Inter Annual Variability of the Acoustic Propagation in the Yellow Sea Identified from a Synoptic Monthly Gridded Database as Compared with GDEM

DTIC Science & Technology

2016-09-01

the world climate is in fact warming due to anthropogenic causes (Anderegg et al. 2010; Solomon et al. 2009). To put this in terms for this research ...2006). The present research uses a 0.5’ resolution. B. SEDIMENTS DATABASE There are four openly available sediment databases: Enhanced, Standard...DISTRIBUTION CODE 13. ABSTRACT (maximum 200 words) This research investigates the inter-annual acoustic variability in the Yellow Sea identified from

Inter-subject variability modulates phonological advance planning in the production of adjective-noun phrases.

PubMed

Michel Lange, Violaine; Laganaro, Marina

2014-01-01

The literature on advance phonological planning in adjective-noun phrases (NPs) presents diverging results: while many experimental studies suggest that the entire NP is encoded before articulation, other results favor a span of encoding limited to the first word. Although cross-linguistic differences in the structure of adjective-NPs may account for some of these contrasting results, divergences have been reported even among similar languages and syntactic structures. Here we examined whether inter-individual differences account for variability in the span of phonological planning in the production of French NPs, where previous results indicated encoding limited to the first word. The span of phonological encoding is tested with the picture-word interference (PWI) paradigm using phonological distractors related to the noun or to the adjective of the NPs. In Experiment 1, phonological priming effects were limited to the first word in adjective NPs whichever the position of the adjective (pre-nominal or post-nominal). Crucially, phonological priming effects on the second word interacted with speakers' production speed suggesting different encoding strategies for participants. In Experiment 2, we tested this hypothesis further with a larger group of participants. Results clearly showed that slow and fast initializing participants presented different phonological priming patterns on the last element of adjective-NPs: while the first word was primed by a distractor for all speakers, only the slow speaker group presented a priming effect on the second element of the NP. These results show that the span of phonological encoding is modulated by inter-individual strategies: in experimental paradigms some speakers plan word by word whereas others encode beyond the initial word. We suggest that the diverging results reported in the literature on advance phonological planning may partly be reconciled in light of the present results.

Development and evaluation of an instrument for assessing brief behavioral change interventions.

PubMed

Strayer, Scott M; Martindale, James R; Pelletier, Sandra L; Rais, Salehin; Powell, Jon; Schorling, John B

2011-04-01

To develop an observational coding instrument for evaluating the fidelity and quality of brief behavioral change interventions based on the behavioral theories of the 5 A's, Stages of Change and Motivational Interviewing. Content and face validity were assessed prior to an intervention where psychometric properties were evaluated with a prospective cohort of 116 medical students. Properties assessed included the inter-rater reliability of the instrument, internal consistency of the full scale and sub-scales and descriptive statistics of the instrument. Construct validity was assessed based on student's scores. Inter-rater reliability for the instrument was 0.82 (intraclass correlation). Internal consistency for the full scale was 0.70 (KR20). Internal consistencies for the sub-scales were as follows: MI intervention component (KR20=.7); stage-appropriate MI-based intervention (KR20=.55); MI spirit (KR20=.5); appropriate assessment (KR20=.45) and appropriate assisting (KR20=.56). The instrument demonstrated good inter-rater reliability and moderate overall internal consistency when used to assess performing brief behavioral change interventions by medical students. This practical instrument can be used with minimal training and demonstrates promising psychometric properties when evaluated with medical students counseling standardized patients. Further testing is required to evaluate its usefulness in clinical settings. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Non-coincident Inter-instrument Comparisons of Ozone Measurements Using Quasi-conservative Coordinates

NASA Technical Reports Server (NTRS)

Lait, L. R.; Newman, P. A.; Schoeberl, M. R.; McGee, T.; Twigg, T.; Browell, E.; Bevilacqua, R.; Andersen, S. B.; DeBacker, H.; Benesova, A.

2004-01-01

Ozone measurements from ozonesondes, AROTAL, DIAL, and POAM III instruments during the SOLVE-2/VINTERSOL period are composited in a time-varying, flow-following quasi-conservative (PV-6) coordinate space; the resulting composites from each instrument are mapped onto the other instruments locations and times. The mapped data are then used to intercompare data from the different instruments. Overall, the four data sets are found to be in good agreement. AROTAL shows somewhat lower values below 16 km, and DIAL has a positive bias at the upper limits of its altitude range. These intercomparisons are consistent with those obtained from more conventional near-coincident profiles, where available. Although the PV-theta mapping technique entails larger uncertainties of individual profile differences compared to direct near-coincident comparisons, the ability to include much larger numbers of comparisons can make this technique advantageous.

Physical fitness predicts technical-tactical and time-motion profile in simulated Judo and Brazilian Jiu-Jitsu matches

PubMed Central

Gentil, Paulo; Bueno, João C.A.; Follmer, Bruno; Marques, Vitor A.; Del Vecchio, Fabrício B.

2018-01-01

Background Among combat sports, Judo and Brazilian Jiu-Jitsu (BJJ) present elevated physical fitness demands from the high-intensity intermittent efforts. However, information regarding how metabolic and neuromuscular physical fitness is associated with technical-tactical performance in Judo and BJJ fights is not available. This study aimed to relate indicators of physical fitness with combat performance variables in Judo and BJJ. Methods The sample consisted of Judo (n = 16) and BJJ (n = 24) male athletes. At the first meeting, the physical tests were applied and, in the second, simulated fights were performed for later notational analysis. Results The main findings indicate: (i) high reproducibility of the proposed instrument and protocol used for notational analysis in a mobile device; (ii) differences in the technical-tactical and time-motion patterns between modalities; (iii) performance-related variables are different in Judo and BJJ; and (iv) regression models based on metabolic fitness variables may account for up to 53% of the variances in technical-tactical and/or time-motion variables in Judo and up to 31% in BJJ, whereas neuromuscular fitness models can reach values up to 44 and 73% of prediction in Judo and BJJ, respectively. When all components are combined, they can explain up to 90% of high intensity actions in Judo. Discussion In conclusion, performance prediction models in simulated combat indicate that anaerobic, aerobic and neuromuscular fitness variables contribute to explain time-motion variables associated with high intensity and technical-tactical variables in Judo and BJJ fights. PMID:29844991

Implementing and Evaluating a National Certification Technical Skills Examination: The Colorectal Objective Structured Assessment of Technical Skill.

PubMed

de Montbrun, Sandra; Roberts, Patricia L; Satterthwaite, Lisa; MacRae, Helen

2016-07-01

To implement the Colorectal Objective Structured Assessment of Technical skill (COSATS) into American Board of Colon and Rectal Surgery (ABCRS) certification and build evidence of validity for the interpretation of the scores of this high stakes assessment tool. Currently, technical skill assessment is not a formal component of board certification. With the technical demands of surgical specialties, documenting competence in technical skill at the time of certification with a valid tool is ideal. In September 2014, the COSATS was a mandatory component of ABCRS certification. Seventy candidates took the examination, with their performance evaluated by expert colorectal surgeons using a task-specific checklist, global rating scale, and overall performance scale. Passing scores were set and compared using 2 standard setting methodologies, using a compensatory and conjunctive model. Inter-rater reliability and the reliability of the pass/fail decision were calculated using Cronbach alpha and Subkoviak methodology, respectively. Overall COSATS scores and pass/fail status were compared with results on the ABCRS oral examination. The pass rate ranged from 85.7% to 90%. Inter-rater reliability (0.85) and reliability of the pass/fail decision (0.87 and 0.84) were high. A low positive correlation (r= 0.25) was seen between the COSATS and oral examination. All individuals who failed the COSATS passed the ABCRS oral examination. COSATS is the first technical skill examination used in national surgical board certification. This study suggests that the current certification process may be failing to identify individuals who have demonstrated technical deficiencies on this standardized assessment tool.

Development and Validation of a Practical Instrument for Injury Prevention: The Occupational Safety and Health Monitoring and Assessment Tool (OSH-MAT).

PubMed

Sun, Yi; Arning, Martin; Bochmann, Frank; Börger, Jutta; Heitmann, Thomas

2018-06-01

The Occupational Safety and Health Monitoring and Assessment Tool (OSH-MAT) is a practical instrument that is currently used in the German woodworking and metalworking industries to monitor safety conditions at workplaces. The 12-item scoring system has three subscales rating technical, organizational, and personnel-related conditions in a company. Each item has a rating value ranging from 1 to 9, with higher values indicating higher standard of safety conditions. The reliability of this instrument was evaluated in a cross-sectional survey among 128 companies and its validity among 30,514 companies. The inter-rater reliability of the instrument was examined independently and simultaneously by two well-trained safety engineers. Agreement between the double ratings was quantified by the intraclass correlation coefficient and absolute agreement of the rating values. The content validity of the OSH-MAT was evaluated by quantifying the association between OSH-MAT values and 5-year average injury rates by Poisson regression analysis adjusted for the size of the companies and industrial sectors. The construct validity of OSH-MAT was examined by principle component factor analysis. Our analysis indicated good to very good inter-rater reliability (intraclass correlation coefficient = 0.64-0.74) of OSH-MAT values with an absolute agreement of between 72% and 81%. Factor analysis identified three component subscales that met exactly the structure theory of this instrument. The Poisson regression analysis demonstrated a statistically significant exposure-response relationship between OSH-MAT values and the 5-year average injury rates. These analyses indicate that OSH-MAT is a valid and reliable instrument that can be used effectively to monitor safety conditions at workplaces.

Quantifying the impact of the major driving mechanisms of inter-annual variability of salinity in the North Sea

NASA Astrophysics Data System (ADS)

Núñez-Riboni, Ismael; Akimova, Anna

2017-05-01

New 67-year long (1948-2014) gridded time series of salinity in the North Sea at all depths allowed to quantify, spatially resolved, the amount of inter-annual salinity variability explained by each of its driving mechanisms: sea level pressure (SLP), precipitation, river run-off, zonal and meridional winds and currents over the eastern North Atlantic. For the current data, not only annual averages but also their deviations, as measure of turbulence, were considered. Our results summarize and expand the knowledge gathered in the last 50 years about the mechanisms driving inter-annual variability of salinity in the North Sea. Three mechanisms, uncorrelated with each other and acting over separate regions of the North Sea, arise as most important: (1) River run-off from continental Europe explains 50-80% of inter-annual salinity variations at lag 0 in the Southern and German Bights and the Norwegian Trench up to the connection with the North Atlantic, down to the seabed near the coasts and to the deep Norwegian Trench (100 m); (2) Remote variations of salinity in the Rockall Trough explain 70% of salinity variations of the tongue of high salinity in the northwestern North Sea with a lag of one year and down the water column; (3) The Neva discharge explains 60% of salinity changes in Skagerrak and southern Norwegian trench at lag 0. An explanation for this correlation might be the Baltic freshwater outflow being modulated by the Neva discharge through intensification of the estuarine gravitational circulation. We confirmed known relations between river run-off, precipitation over continental Europe, SLP over northern Europe and zonal wind over western Europe. Linked to these changes, we found also changes of meridional wind north of Scotland favoring eastward Ekman transport of salty North Atlantic waters into the North Sea off the Norwegian coast. Excluding this only case, we found no significant correlation between wind-driven currents and North Sea salinity changes

Aeronautic instruments. Section I : general classification of instruments and problems including bibliography

NASA Technical Reports Server (NTRS)

Hersey, Mayo D

1923-01-01

This report is intended as a technical introduction to the series of reports on aeronautic instruments. It presents a discussion of those subjects which are common to all instruments. First, a general classification is given, embracing all types of instruments used in aeronautics. Finally, a classification is given of the various problems confronted by the instrument expert and investigator. In this way the following groups of problems are brought up for consideration: problems of mechanical design, human factor, manufacturing problems, supply and selection of instruments, problems concerning the technique of testing, problems of installation, problems concerning the use of instruments, problems of maintenance, and physical research problems. This enumeration of problems which are common to instruments in general serves to indicate the different points of view which should be kept in mind in approaching the study of any particular instrument.

Translation and adaption of the interRAI suite to local requirements in Belgian hospitals

PubMed Central

2012-01-01

Background The interRAI Suite contains comprehensive geriatric assessment tools designed for various healthcare settings. Although each instrument is developed for a particular population, together they form an integrated health evaluation system. The interRAI Acute Care Minimum Data Set (interRAI AC) is tailored for hospitalized older persons. Our aim in this study was to translate and adapt the interRAI AC to the Belgian hospital context, where it can be used together with the interRAI Home Care (HC) and the interRAI Long Term Care Facility (LTCF). Methods A systematic, comprehensive, and rigorous 10-step approach was used to adapt the interRAI AC to local requirements. After linguistic translation by an official translator, five researchers assessed the translation for appropriate hospital jargon. Three researchers double-checked for translation accuracy and proposed additional items. A provisional version was converted into the three official languages of Belgium—Flemish, French, and German. Next, a multidisciplinary panel of nine experts judged item relevance to the Belgian care context and advised which country-specific items should be added. After these suggestions were incorporated into the interRAI AC, hospital staff from nine Flemish hospitals field-tested the tool in their practice. After evaluating field-test results, we compared the interRAI AC with Belgian versions of the interRAI HC and interRAI LTCF. Next, the Flemish, French, and German versions of the Belgian interRAI portfolio were harmonized. Finally, we submitted the Belgian interRAI AC to the interRAI organization for ratification. Results Eighteen administrative items of the interRAI AC were adapted to the Belgian healthcare context (e.g., usual residence, formal community services prior to admission). Fourteen items assessing the ‘informal caregiver’, and 17 items, including country-specific items, were added (e.g., advanced directive for euthanasia). Conclusions The interRAI AC was

The ceilometer inter-comparison campaign CeiLinEx2015

NASA Astrophysics Data System (ADS)

Mattis, Ina; Begbie, Robert; Boyouk, Neda; Bravo-Aranda, Juan Antonio; Brettle, Mike; Cermak, Jan; Drouin, Marc-Antoine; Geiß, Alexander; Görsdorf, Ulrich; Haefele, Alexander; Haeffelin, Martial; Hervo, Maxime; Komínková, Kateřina; Leinweber, Ronny; Müller, Gerhard; Münkel, Christoph; Pattantyús-Ábrahám, Margit; Pönitz, Kornelia; Wagner, Frank; Wiegner, Matthias

2016-04-01

Ceilometers are well established instruments for the detection of cloud base heights. Since about 2000, modern ceilometer types (mainly CHM15k, CL51, and CL31) are used also for investigations of the top height of the planetary boundary layer and for quantitative retrievals of vertical profiles of backscatter coefficients. In the framework of the European projects E-PROFILE and TOPROF, tools for the exchange of ceilometer data among European meteorological services, as well as calibration and visualization procedures are developed and established. Unfortunately, the national networks are equipped with instruments of different generations and different manufacturers. In order to quantify and reduce those inhomogeneities, the ceilometer inter-comparison experiment CeiLinEx2015 was performed between June and September 2015 at the Meteorological Observatory Lindenberg, Germany. We tested six different instrument types: LD40, CL31, CL51, CHM15k, CHM15kx, and CS135. Each instrument type was represented by two instruments to estimate the instrument-to-instrument variability and the influence of different firmware versions. Two Raman lidars (RAMSES and RALPH), operated by German Meteorological Service (DWD) are used as reference instruments. Further ancillary data are available, e.g., hourly eye observations, four radio soundings per day, and AERONET sun photometer observations. Beside the typical vertically pointing measurement scheme, we performed special measurements with horizontal pointing direction or blocked receiver telescope. During the experiment, we could collect measurements under very different meteorological situations: Several clear nights allow for Rayleigh-Calibration (see Hervo and CeiLinEx2015 team [EGU2016-4785]), a strong event of Sahara dust intrusion can be used to study the behaviour of the instruments in presence of large, non-spherical particles (like volcanic ash). Further investigations focus, e.g., on the detection of very low cloud base

Toward human resource management in inter-professional health practice: linking organizational culture, group identity and individual autonomy.

PubMed

Tataw, David

2012-01-01

The literature on team and inter-professional care practice describes numerous barriers to the institutionalization of inter-professional healthcare. Responses to slow institutionalization of inter-professional healthcare practice have failed to describe change variables and to identify change agents relevant to inter-professional healthcare practice. The purpose of this paper is to (1) describe individual and organizational level barriers to collaborative practice in healthcare; (2) identify change variables relevant to the institutionalization of inter-professional practice at individual and organizational levels of analysis; and (3) identify human resource professionals as change agents and describe how the strategic use of the human resource function could transform individual and organizational level change variables and therefore facilitate the healthcare system's shift toward inter-professional practice. A proposed program of institutionalization includes the following components: a strategic plan to align human resource functions with organizational level inter-professional healthcare strategies, activities to enhance professional competencies and the organizational position of human resource personnel, activities to integrate inter-professional healthcare practices into the daily routines of institutional and individual providers, activities to stand up health provider champions as permanent leaders of inter-professional teams with human resource professionals as consultants and activities to bring all key players to the table including health providers. Copyright © 2012 John Wiley & Sons, Ltd.

22 CFR 1003.4 - Inter-American Foundation system of records requirements.

Code of Federal Regulations, 2010 CFR

2010-04-01

..., technical, and physical safeguards to insure the security and confidentiality of records and to protect against any anticipated threats or hazards to their security or integrity which could result in..., retention, and disposal of the records; (6) The title and business address of the Inter-American Foundation...

Inter-physician agreement on the readiness of sick-listed employees to return to work.

PubMed

Schreuder, Jolanda A H; Roelen, Corné A M; de Boer, Mintje; Brouwer, Sandra; Groothoff, Johan W

2012-01-01

To determine the agreement between occupational physician (OP) ratings of an employee's readiness to return to work (RRTW). Anonymized written vignettes of 132 employees, sick-listed for at least 3 weeks, were reviewed by 5 OPs. The OPs intuitively rated RRTW as the ability (knowledge and skills) and willingness (motivation and confidence) of sick-listed employees to resume work. Inter-OP percentages of agreement were calculated and Cohen's kappas (κ) were determined to correct for agreement by chance. The percentage of agreement between OPs was 57% (range 39-89%) on the ability and 63% (range 48-87%) on the willingness of sick-listed employees to resume work. The mean κ was 0.14 (range from -0.21 to 0.79) for ability and 0.25 (range from -0.11 to 0.74) for willingness. The OP-rating of RRTW of employees sick-listed with mental disorders did not differ from the OP-rating of RRTW of employees with musculoskeletal disorders. The inter-OP agreement on intuitively rated RRTW showed a wide variability, which accentuates the need for instruments to establish an employee's RRTW and for training in giving well founded return to work recommendations.

Social interactions and college enrollment: A combined school fixed effects/instrumental variables approach.

PubMed

Fletcher, Jason M

2015-07-01

This paper provides some of the first evidence of peer effects in college enrollment decisions. There are several empirical challenges in assessing the influences of peers in this context, including the endogeneity of high school, shared group-level unobservables, and identifying policy-relevant parameters of social interactions models. This paper addresses these issues by using an instrumental variables/fixed effects approach that compares students in the same school but different grade-levels who are thus exposed to different sets of classmates. In particular, plausibly exogenous variation in peers' parents' college expectations are used as an instrument for peers' college choices. Preferred specifications indicate that increasing a student's exposure to college-going peers by ten percentage points is predicted to raise the student's probability of enrolling in college by 4 percentage points. This effect is roughly half the magnitude of growing up in a household with married parents (vs. an unmarried household). Copyright © 2015 Elsevier Inc. All rights reserved.

Social Interactions and College Enrollment: A Combined School Fixed Effects/Instrumental Variables Approach

PubMed Central

Fletcher, Jason M.

2015-01-01

This paper provides some of the first evidence of peer effects in college enrollment decisions. There are several empirical challenges in assessing the influences of peers in this context, including the endogeneity of high school, shared group-level unobservables, and identifying policy-relevant parameters of social interactions models. This paper addresses these issues by using an instrumental variables/fixed effects approach that compares students in the same school but different grade-levels who are thus exposed to different sets of classmates. In particular, plausibly exogenous variation in peers’ parents’ college expectations are used as an instrument for peers’ college choices. Preferred specifications indicate that increasing a student’s exposure to college-going peers by ten percentage points is predicted to raise the student’s probability of enrolling in college by 4 percentage points. This effect is roughly half the magnitude of growing up in a household with married parents (vs. an unmarried household). PMID:26004476

Project DIVIDE Instrument Development. Technical Report # 0810

ERIC Educational Resources Information Center

Ketterlin-Geller, Leanne; Jung, Eunju; Geller, Josh; Yovanoff, Paul

2008-01-01

In this technical report, we describe the development of cognitive diagnostic test items that form the basis of the diagnostic system for Project DIVIDE (Dynamic Instruction Via Individually Designed Environments). The construct underlying the diagnostic test is division of fractions. We include a description of the process we used to identify the…

Gait assessment using the Microsoft Xbox One Kinect: Concurrent validity and inter-day reliability of spatiotemporal and kinematic variables.

PubMed

Mentiplay, Benjamin F; Perraton, Luke G; Bower, Kelly J; Pua, Yong-Hao; McGaw, Rebekah; Heywood, Sophie; Clark, Ross A

2015-07-16

The revised Xbox One Kinect, also known as the Microsoft Kinect V2 for Windows, includes enhanced hardware which may improve its utility as a gait assessment tool. This study examined the concurrent validity and inter-day reliability of spatiotemporal and kinematic gait parameters estimated using the Kinect V2 automated body tracking system and a criterion reference three-dimensional motion analysis (3DMA) marker-based camera system. Thirty healthy adults performed two testing sessions consisting of comfortable and fast paced walking trials. Spatiotemporal outcome measures related to gait speed, speed variability, step length, width and time, foot swing velocity and medial-lateral and vertical pelvis displacement were examined. Kinematic outcome measures including ankle flexion, knee flexion and adduction and hip flexion were examined. To assess the agreement between Kinect and 3DMA systems, Bland-Altman plots, relative agreement (Pearson's correlation) and overall agreement (concordance correlation coefficients) were determined. Reliability was assessed using intraclass correlation coefficients, Cronbach's alpha and standard error of measurement. The spatiotemporal measurements had consistently excellent (r≥0.75) concurrent validity, with the exception of modest validity for medial-lateral pelvis sway (r=0.45-0.46) and fast paced gait speed variability (r=0.73). In contrast kinematic validity was consistently poor to modest, with all associations between the systems weak (r<0.50). In those measures with acceptable validity, the inter-day reliability was similar between systems. In conclusion, while the Kinect V2 body tracking may not accurately obtain lower body kinematic data, it shows great potential as a tool for measuring spatiotemporal aspects of gait. Copyright © 2015 Elsevier Ltd. All rights reserved.

An Integrated Workflow To Assess Technical and Biological Variability of Cell Population Frequencies in Human Peripheral Blood by Flow Cytometry.

PubMed

Burel, Julie G; Qian, Yu; Lindestam Arlehamn, Cecilia; Weiskopf, Daniela; Zapardiel-Gonzalo, Jose; Taplitz, Randy; Gilman, Robert H; Saito, Mayuko; de Silva, Aruna D; Vijayanand, Pandurangan; Scheuermann, Richard H; Sette, Alessandro; Peters, Bjoern

2017-02-15

In the context of large-scale human system immunology studies, controlling for technical and biological variability is crucial to ensure that experimental data support research conclusions. In this study, we report on a universal workflow to evaluate both technical and biological variation in multiparameter flow cytometry, applied to the development of a 10-color panel to identify all major cell populations and T cell subsets in cryopreserved PBMC. Replicate runs from a control donation and comparison of different gating strategies assessed the technical variability associated with each cell population and permitted the calculation of a quality control score. Applying our panel to a large collection of PBMC samples, we found that most cell populations showed low intraindividual variability over time. In contrast, certain subpopulations such as CD56 T cells and Temra CD4 T cells were associated with high interindividual variability. Age but not gender had a significant effect on the frequency of several populations, with a drastic decrease in naive T cells observed in older donors. Ethnicity also influenced a significant proportion of immune cell population frequencies, emphasizing the need to account for these covariates in immune profiling studies. We also exemplify the usefulness of our workflow by identifying a novel cell-subset signature of latent tuberculosis infection. Thus, our study provides a universal workflow to establish and evaluate any flow cytometry panel in systems immunology studies. Copyright © 2017 by The American Association of Immunologists, Inc.

[Instruments for quantitative methods of nursing research].

PubMed

Vellone, E

2000-01-01

Instruments for quantitative nursing research are a mean to objectify and measure a variable or a phenomenon in the scientific research. There are direct instruments to measure concrete variables and indirect instruments to measure abstract concepts (Burns, Grove, 1997). Indirect instruments measure the attributes by which a concept is made of. Furthermore, there are instruments for physiologic variables (e.g. for the weight), observational instruments (Check-lists e Rating Scales), interviews, questionnaires, diaries and the scales (Check-lists, Rating Scales, Likert Scales, Semantic Differential Scales e Visual Anologue Scales). The choice to select an instrument or another one depends on the research question and design. Instruments research are very useful in research both to describe the variables and to see statistical significant relationships. Very carefully should be their use in the clinical practice for diagnostic assessment.

Genetic basis of inter-individual variability in the effects of exercise on the alleviation of lifestyle-related diseases

PubMed Central

Mori, Masayuki; Higuchi, Keiichi; Sakurai, Akihiro; Tabara, Yasuharu; Miki, Tetsuro; Nose, Hiroshi

2009-01-01

Habitual exercise training, including a high-intensity interval walking programme, improves cardiorespiratory fitness and alleviates lifestyle-related diseases, such as obesity, hypertension and dyslipidaemia. However, the extent of improvement has been shown to differ substantially among individuals for various exercise regimens. A body of literature has demonstrated that gene polymorphisms could account for the inter-individual variability in the improvement of risk factors for lifestyle-related diseases following exercise training. However, the fractions of the variability explained by the polymorphisms are small (∼5%). Also, it is likely that the effects of gene polymorphisms differ with exercise regimens and subject characteristics. These observations suggest the necessity for further studies to exhaustively identify such gene polymorphisms. More importantly, the physiological and molecular genetic mechanisms by which gene polymorphisms interact with exercise to influence the improvements of risk factors for lifestyle-related diseases differentially remain to be clarified. A better understanding of these issues should lead to more effective integration of exercise to optimize the treatment and management of individuals with lifestyle-related diseases. PMID:19736300

Inter-individual variability in the patterns of responses for electromyography and mechanomyography during cycle ergometry using an RPE-clamp model.

PubMed

Cochrane-Snyman, Kristen C; Housh, Terry J; Smith, Cory M; Hill, Ethan C; Jenkins, Nathaniel D M; Schmidt, Richard J; Johnson, Glen O

2016-09-01

To examine inter-individual variability versus composite models for the patterns of responses for electromyography (EMG) and mechanomyography (MMG) versus time relationships during moderate and heavy cycle ergometry using a rating of perceived exertion (RPE) clamp model. EMG amplitude (amplitude root-mean-square, RMS), EMG mean power frequency (MPF), MMG-RMS, and MMG-MPF were collected during two, 60-min rides at a moderate (RPE at the gas exchange threshold; RPEGET) and heavy (RPE at 15 % above the GET; RPEGET+15 %) intensity when RPE was held constant (clamped). Composite (mean) and individual responses for EMG and MMG parameters were compared during each 60-min ride. There was great inter-individual variability for each EMG and MMG parameters at RPEGET and RPEGET+15 %. Composite models showed decreases in EMG-RMS (r (2) = -0.92 and R (2) = 0.96), increases in EMG-MPF (R (2) = 0.90), increases in MMG-RMS (r (2) = 0.81 and 0.55), and either no change or a decrease (r (2) = 0.34) in MMG-MPF at RPEGET and RPEGET+15 %, respectively. The results of the present study indicated that there were differences between composite and individual patterns of responses for EMG and MMG parameters during moderate and heavy cycle ergometry at a constant RPE. Thus, composite models did not represent the unique muscle activation strategies exhibited by individual responses when cycling in the moderate and heavy intensity domains when using an RPE-clamp model.

Too much ado about instrumental variable approach: is the cure worse than the disease?

PubMed

Baser, Onur

2009-01-01

To review the efficacy of instrumental variable (IV) models in addressing a variety of assumption violations to ensure standard ordinary least squares (OLS) estimates are consistent. IV models gained popularity in outcomes research because of their ability to consistently estimate the average causal effects even in the presence of unmeasured confounding. However, in order for this consistent estimation to be achieved, several conditions must hold. In this article, we provide an overview of the IV approach, examine possible tests to check the prerequisite conditions, and illustrate how weak instruments may produce inconsistent and inefficient results. We use two IVs and apply Shea's partial R-square method, the Anderson canonical correlation, and Cragg-Donald tests to check for weak instruments. Hall-Peixe tests are applied to see if any of these instruments are redundant in the analysis. A total of 14,952 asthma patients from the MarketScan Commercial Claims and Encounters Database were examined in this study. Patient health care was provided under a variety of fee-for-service, fully capitated, and partially capitated health plans, including preferred provider organizations, point of service plans, indemnity plans, and health maintenance organizations. We used controller-reliever copay ratio and physician practice/prescribing patterns as an instrument. We demonstrated that the former was a weak and redundant instrument producing inconsistent and inefficient estimates of the effect of treatment. The results were worse than the results from standard regression analysis. Despite the obvious benefit of IV models, the method should not be used blindly. Several strong conditions are required for these models to work, and each of them should be tested. Otherwise, bias and precision of the results will be statistically worse than the results achieved by simply using standard OLS.

Missing Oral Health-Related Data in the interRAI-HC - Associations with Selected Variables of General Health and the Effect of Multiple Imputation on the Relationship between Oral and General Health.

PubMed

Krausch-Hofmann, Stefanie; Bogaerts, Kris; Hofmann, Michael; de Almeida Mello, Johanna; Fávaro Moreira, Nádia Cristina; Lesaffre, Emmanuel; Declerck, Dominique; Declercq, Anja; Duyck, Joke

2015-01-01

Missing data within the comprehensive geriatric assessment of the interRAI suite of assessment instruments potentially imply the under-detection of conditions that require care as well as the risk of biased statistical results. Impaired oral health in older individuals has to be registered accurately as it causes pain and discomfort and is related to the general health status. This study was based on interRAI-Home Care (HC) baseline data from 7590 subjects (mean age 81.2 years, SD 6.9) in Belgium. It was investigated if missingness of the oral health-related items was associated with selected variables of general health. It was also determined if multiple imputation of missing data affected the associations between oral and general health. Multivariable logistic regression was used to determine if the prevalence of missingness in the oral health-related variables was associated with activities of daily life (ADLH), cognitive performance (CPS2) and depression (DRS). Associations between oral health and ADLH, CPS2 and DRS were determined, with missing data treated by 1. the complete-case technique and 2. by multiple imputation, and results were compared. The individual oral health-related variables had a similar proportion of missing values, ranging from 16.3% to 17.2%. The prevalence of missing data in all oral health-related variables was significantly associated with symptoms of depression (dental prosthesis use OR 1.66, CI 1.41-1.95; damaged teeth OR 1.74, CI 1.48-2.04; chewing problems OR 1.74, CI 1.47-2.05; dry mouth OR 1.65, CI 1.40-1.94). Missingness in damaged teeth (OR 1.27, CI 1.08-1.48), chewing problems (OR 1.22, CI 1.04-1.44) and dry mouth (OR 1.23, CI 1.05-1.44) occurred more frequently in cognitively impaired subjects. ADLH was not associated with the prevalence of missing data. When comparing the complete-case technique with the multiple imputation approach, nearly identical odds ratios characterized the associations between oral and general health

An Introduction to the Global Space-based Inter-Calibration System from a EUMETSAT Perspective

NASA Astrophysics Data System (ADS)

Wagner, S. C.; Hewison, T.; Roebeling, R. A.; Koenig, M.; Schulz, J.; Miu, P.

2012-04-01

The Global Space-based Inter-Calibration System (GSICS) (Goldberg and al. 2011) is an international collaborative effort which aims to monitor, improve and harmonize the quality of observations from operational weather and environmental satellites of the Global Observing System (GOS). GSICS aims at ensuring consistent accuracy among space-based observations worldwide for climate monitoring, weather forecasting, and environmental applications. This is achieved through a comprehensive calibration strategy, which involves monitoring instrument performances, operational inter-calibration of satellite instruments, tying the measurements to absolute references and standards, and recalibration of archived data. A major part of this strategy involves direct comparison of collocated observations from pairs of satellite instruments, which are used to systematically generate calibration functions to compare and correct the calibration of monitored instruments to references. These GSICS Corrections are needed for accurately integrating data from multiple observing systems into both near real-time and re-analysis products, applications and services. This paper gives more insight into the activities carried out by EUMETSAT as a GSICS Processing and Research Centre. Currently these are closely bound to the in-house development and operational implementation of calibration methods for solar and thermal band channels of geostationary and polar-orbiting satellites. They include inter-calibration corrections for Meteosat imagers using reference instruments such as the Moderate Resolution Imaging Spectroradiometer (MODIS) on-board the Aqua satellite for solar band channels, the Infrared Atmospheric Sounding Interferometer (IASI) on-board Metop-A and, for historic archive data, the High-resolution InfraRed Sounder (HIRS). Additionally, bias monitoring is routinely performed, allowing users to visualise the calibration accuracy of the instruments in near real-time. These activities are

Reliability of visual and instrumental color matching.

PubMed

Igiel, Christopher; Lehmann, Karl Martin; Ghinea, Razvan; Weyhrauch, Michael; Hangx, Ysbrand; Scheller, Herbert; Paravina, Rade D

2017-09-01

The aim of this investigation was to evaluate intra-rater and inter-rater reliability of visual and instrumental shade matching. Forty individuals with normal color perception participated in this study. The right maxillary central incisor of a teaching model was prepared and restored with 10 feldspathic all-ceramic crowns of different shades. A shade matching session consisted of the observer (rater) visually selecting the best match by using VITA classical A1-D4 (VC) and VITA Toothguide 3D Master (3D) shade guides and the VITA Easyshade Advance intraoral spectrophotometer (ES) to obtain both VC and 3D matches. Three shade matching sessions were held with 4 to 6 weeks between sessions. Intra-rater reliability was assessed based on the percentage of agreement for the three sessions for the same observer, whereas the inter-rater reliability was calculated as mean percentage of agreement between different observers. The Fleiss' Kappa statistical analysis was used to evaluate visual inter-rater reliability. The mean intra-rater reliability for the visual shade selection was 64(11) for VC and 48(10) for 3D. The corresponding ES values were 96(4) for both VC and 3D. The percentages of observers who matched the same shade with VC and 3D were 55(10) and 43(12), respectively, while corresponding ES values were 88(8) for VC and 92(4) for 3D. The results for visual shade matching exhibited a high to moderate level of inconsistency for both intra-rater and inter-rater comparisons. The VITA Easyshade Advance intraoral spectrophotometer exhibited significantly better reliability compared with visual shade selection. This study evaluates the ability of observers to consistently match the same shade visually and with a dental spectrophotometer in different sessions. The intra-rater and inter-rater reliability (agreement of repeated shade matching) of visual and instrumental tooth color matching strongly suggest the use of color matching instruments as a supplementary tool in

Wireless Instrumentation Systems for Flight Testing at NASA AFRC

NASA Technical Reports Server (NTRS)

Hang, Richard

2017-01-01

NASA Armstrong Flight Research Center is revolutionizing its traditional wired instrumentation systems with wireless technologies. This effort faces many technical challenges, such as spectrum compliance, time synchronization, power distribution and airworthiness. This presentation summarizes NASA AFRC's flight test capabilities with current conventional instrumentation methodology and highlights the technical challenges of wireless systems used for flight test research applications.

InterGeo II: International Geographical Achievement Test. Field Trials Report and Test (Secondary Schools, Grade 8).

ERIC Educational Resources Information Center

Niemz, Gunter; Stoltman, Joseph P.

InterGeo II, a project of the Commission on Geographical Education (CGE) of the International Geographical Union (IGU), has developed a broadly based, field-trialed testing instrument for making cross-national comparisons of achievement in geography. Field trials of InterGeo II were held in 23 countries. Data were analyzed for national achievement…

Development and Psychometric Properties of an Assessment for Persons with Intellectual Disability--The InterRAI ID

ERIC Educational Resources Information Center

Martin, Lynn; Hirdes, John P.; Fries, Brant E.; Smith, Trevor F.

2007-01-01

This paper describes the development of the interRAI-Intellectual Disability (interRAI ID), a comprehensive instrument that assesses all key domains of interest to service providers relative to a person with an intellectual disability (ID). The authors report on the reliability and validity of embedded scales for cognition, self-care, aggression,…

Impact of inter-seasonal solar variability on the association of lower troposphere and cold point tropopause in the tropics: Observations using RO data from COSMIC

NASA Astrophysics Data System (ADS)

Kumar, V.; Dhaka, S. K.; Ho, Shu-Peng; Singh, Narendra; Singh, Vir; Reddy, K. K.; Chun, H.-Y.

2017-12-01

Association of lower tropospheric variations with the cold point tropopause (CPT) is examined on inter-seasonal basis over the tropical region (30°N-30°S) during 2007-2010 using COSMIC/FORMOST-3 Radio Occultation (RO) data. Temperature analyses for this association are shown over different regions of the globe having contrast topography namely over Western Pacific sector, Indian sector, and African sector. Correlation coefficient (r), taken as a measurement of association, show specific longitudinal differences between the lower troposphere (from 1 km to 5 km height) and the CPT. The northern and southern hemispheres show contrast coupling of temperature variation between lower tropospheric region and the CPT. Land and ocean effects are found to contribute in a different way to the correlation coefficient. Analyses show symmetrical structure of 'r' on both sides of the equator over the African region, as data include mostly land region on both side of equator. Data represent positive correlation (r 0.5) over 15°-20° latitudes on either side of the equator over the African region, suggesting strong hold of the inter-seasonal variation of solar diabatic heating influence over the tropic of Cancer and tropic of Capricorn. On the other hand, there is a contrast behaviour over the Indian region, 'r' is nearly negative ( - 1.0) each year in the southern hemisphere (SH) and positive ( 0.4) in the northern hemisphere (NH) with a maxima near tropic of Cancer. Western Pacific region is found to display a linear increase in 'r' from negative ( - 1.0) in SH to positive ( 0.8) in NH. In general, 'r' (positive) maximizes over the land region around 15°-20° latitudes, suggesting a control of in phase inter-seasonal solar heating on the coupling of boundary layer/lower troposphere and CPT region, whereas it turns negative over water body. Analyses suggest that variabilities in CPT over different regions of globe show significant inter-seasonal association with the lower

75 FR 44940 - Withdrawal of Application for Duty-Free Entry of Scientific Instruments

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-30

... Entry of Scientific Instruments Applications may be examined between 8:30 A.M. and 5:00 P.M. in Room... determine, inter alia, whether instruments of equivalent scientific value, for the purposes for which the... scientific instrument. They noted that the instrument will be used at a show/demonstration. As noted in the...

76 FR 52936 - Withdrawal of Application for Duty-Free Entry of Scientific Instruments

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-24

... Entry of Scientific Instruments Applications may be examined between 8:30 a.m. and 5 p.m. in Room 3720... determine, inter alia, whether instruments of equivalent scientific value, for the purposes for which the... scientific instrument. They noted that the instrument will be cleared through Customs with duty paid by the...

500-year April-September droughts in the Czech Lands based on documentary data and instrumental records

NASA Astrophysics Data System (ADS)

Řezníčková, Ladislava; Brázdil, Rudolf; Trnka, Miroslav; Dobrovolný, Petr; Kotyza, Oldřich; Štěpánek, Petr; Zahradníček, Pavel; Valášek, Hubert

2013-04-01

This paper analyses temporal and spatial variability of April-September (the vegetation period) droughts in the Czech Lands over the last 500 years. The study is based on different types of documentary data (e.g. chronicles, newspapers, economic sources, weather diaries) covering the pre-instrumental period AD 1501-1804 and on the systematic instrumental meteorological measurements afterwards. Historical-climatological database of the Czech Lands is used for the study of the duration and intensity of drought episodes based on the series of precipitation indices created from documentary data in a 7-degree scale from -3 (extremely dry) to +3 (extremely wet). For the instrumental period of 1805-2012 Palmer's Z-index and PDSI series for mean Czech temperature and precipitation series are used (they were calculated from homogeneous series of 10 and 14 stations respectively). Consequently the 500-year chronology of drought episodes derived from documentary and instrumental data is compiled and the temporal (frequency, seasonality and intensity) and spatial variability of droughts in the Czech Lands from AD 1501 is analysed. The most outstanding drought events are selected and analysed in detail also with respect to their human impacts. The results obtained for the Czech Lands are compared with drought episodes known in Central Europe from other studies and are evaluated with respect to climate variability in Central Europe during the last 500 years (this research is supported by projects InterDrought no. CZ.1.07/2.3.00/20.0248, and GA CR no. P209/11/0956).

Presence and inter-individual variability of carboxylesterases (CES1 and CES2) in human lung.

PubMed

Gabriele, Morena; Puccini, Paola; Lucchi, Marco; Vizziello, Anna; Gervasi, Pier Giovanni; Longo, Vincenzo

2018-04-01

Lungs are pharmacologically active organs and the pulmonary drug metabolism is of interest for inhaled drugs design. Carboxylesterases (CESs) are enzymes catalyzing the hydrolysis of many structurally different ester, amide and carbamate chemicals, including prodrugs. For the first time, the presence, kinetics, inhibition and inter-individual variations of the major liver CES isozymes (CES1 and CES2) were investigated in cytosol and microsomes of human lungs from 20 individuals using 4-nitrophenyl acetate (pNPA), 4-methylumbelliferyl acetate (4-MUA), and fluorescein diacetate (FD) as substrates the rates of hydrolysis (V max ) for pNPA and 4-MUA, unlike FD, were double in microsomes than in cytosol. In these cellular fractions, the V max of pNPA, as CES1 marker, were much greater (30-50-fold) than those of FD, as a specific CES2 marker. Conversely, the K m values were comparable suggesting the involvement of the same enzymes. Inhibition studies revealed that the FD hydrolysis was inhibited by bis-p-nitrophenylphosphate, phenylmethanesulfonyl fluoride, and loperamide (specific for CES2), whereas the pNPA and 4-MUA hydrolysis inhibition was limited. Inhibitors selective for other esterases missed having any effect on above-mentioned activities. In cytosol and microsomes of 20 lung samples, inter-individual variations were found for the hydrolysis of pNPA (2.5-5-fold), FD or 4-MUA (8-15-fold). Similar variations were also observed in CES1 and CES2 gene expression, although determined in a small number (n = 9) of lung samples. The identification of CES1 and CES2 and their variability in human lungs are important for drug metabolism and design of prodrugs which need to be activated in this organ. Copyright © 2018 Elsevier Inc. All rights reserved.

Explaining the inter-annual variability in the ecosystem fluxes of the Brasschaat Scots pine forest: 20 years of eddy flux and pollution monitoring

NASA Astrophysics Data System (ADS)

Horemans, Joanna; Roland, Marilyn; Janssens, Ivan; Ceulemans, Reinhart

2017-04-01

Because of their ecological and recreational value, the health of forest ecosystems and their response to global change and pollution are of high importance. At a number of EuroFlux and ICOS ecosystem sites in Europe - as the Brasschaat forest site - the measurements of ecosystem fluxes of carbon and other gases are combined with vertical profiles of air pollution within the framework of the ICP-Forest monitoring program. The Brasschaat forest is dominated by 80-year old Scots pines (Pinus sylvestris L.), and has a total area of about 150 ha. It is situated near an urban area in the Campine region of Flanders, Belgium and is characterized by a mean annual temperature of 9.8 °C and an annual rainfall of 830 mm. In this contribution we report on a long-term analysis (1996-2016) of the ecosystem carbon and water fluxes, the energy exchanges and the pollutant concentrations (ozone, NOx, NH3, SO2). Particular interest goes to the inter-annual variation of the carbon fluxes and the carbon allocation patterns. The impact of the long-term (aggregated) and the short-term variability in both the meteorological drivers and in the main tropospheric pollutants on the carbon fluxes is examined, as well as their mutual interactive effects and their potential memory effect. The effect of variability in the drivers during the phenological phases (seasonality) on the inter-annual variability of the fluxes is also examined. Basic statistical techniques as well as spectral analyses and data mining techniques are being used.

Differing Roles of Functional Movement Variability as Experience Increases in Gymnastics

PubMed Central

Busquets, Albert; Marina, Michel; Davids, Keith; Angulo-Barroso, Rosa

2016-01-01

Current theories, like Ecological Dynamics, propose that inter-trial movement variability is functional when acquiring or refining movement coordination. Here, we examined how age-based experience levels of gymnasts constrained differences in emergent movement pattern variability during task performance. Specifically, we investigated different roles of movement pattern variability when gymnasts in different age groups performed longswings on a high bar, capturing the range of experience from beginner to advanced status. We also investigated the functionality of the relationships between levels of inter-trial variability and longswing amplitude during performance. One-hundred and thirteen male gymnasts in five age groups were observed performing longswings (with three different experience levels: beginners, intermediates and advanced performers). Performance was evaluated by analysis of key events in coordination of longswing focused on the arm-trunk and trunk-thigh segmental relations. Results revealed that 10 of 18 inter-trial variability measures changed significantly as a function of increasing task experience. Four of ten variability measures conformed to a U-shaped function with age implying exploratory strategies amongst beginners and functional adaptive variability amongst advanced performers. Inter-trial variability of arm-trunk coordination variables (6 of 10) conformed to a \\-shaped curve, as values were reduced to complete the longswings. Changes in coordination variability from beginner to intermediate status were largely restrictive, with only one variability measure related to exploration. Data revealed how inter-trial movement variability in gymnastics, relative to performance outcomes, needs careful interpretation, implying different roles as task experience changes. Key points Inter-trial variability while performing longswings on a high bar was assessed in a large sample (113 participants) divided into five age groups (form beginners to advanced

Right adolescent idiopathic thoracic curve (Lenke 1 A and B): does cost of instrumentation and implant density improve radiographic and cosmetic parameters?

PubMed

Yang, Scott; Jones-Quaidoo, Sean M; Eager, Matthew; Griffin, Justin W; Reddi, Vasantha; Novicoff, Wendy; Shilt, Jeffrey; Bersusky, Ernesto; Defino, Helton; Ouellet, Jean; Arlet, Vincent

2011-07-01

In adolescent idiopathic scoliosis (AIS) there has been a shift towards increasing the number of implants and pedicle screws, which has not been proven to improve cosmetic correction. To evaluate if increasing cost of instrumentation correlates with cosmetic correction using clinical photographs. 58 Lenke 1A and B cases from a multicenter AIS database with at least 3 months follow-up of clinical photographs were used for analysis. Cosmetic parameters on PA and forward bending photographs included angular measurements of trunk shift, shoulder balance, rib hump, and ratio measurements of waist line asymmetry. Pre-op and follow-up X-rays were measured for coronal and sagittal deformity parameters. Cost density was calculated by dividing the total cost of instrumentation by the number of vertebrae being fused. Linear regression and spearman's correlation were used to correlate cost density to X-ray and photo outcomes. Three independent observers verified radiographic and cosmetic parameters for inter/interobserver variability analysis. Average pre-op Cobb angle and instrumented correction were 54° (SD 12.5) and 59% (SD 25) respectively. The average number of vertebrae fused was 10 (SD 1.9). The total cost of spinal instrumentation ranged from $6,769 to $21,274 (Mean $12,662, SD $3,858). There was a weak positive and statistically significant correlation between Cobb angle correction and cost density (r = 0.33, p = 0.01), and no correlation between Cobb angle correction of the uninstrumented lumbar spine and cost density (r = 0.15, p = 0.26). There was no significant correlation between all sagittal X-ray measurements or any of the photo parameters and cost density. There was good to excellent inter/intraobserver variability of all photographic parameters based on the intraclass correlation coefficient (ICC 0.74-0.98). Our method used to measure cosmesis had good to excellent inter/intraobserver variability, and may be an effective tool to objectively assess cosmesis

Predicting Preservice Music Teachers' Performance Success in Instrumental Courses Using Self-Regulated Study Strategies and Predictor Variables

ERIC Educational Resources Information Center

Ersozlu, Zehra N.; Nietfeld, John L.; Huseynova, Lale

2017-01-01

The purpose of this study was to examine the extent to which self-regulated study strategies and predictor variables predict performance success in instrumental performance college courses. Preservice music teachers (N = 123) from a music education department in two state universities in Turkey completed the Music Self-Regulated Studying…

Effect of inter-annual variability in pasture growth and irrigation response on farm productivity and profitability based on biophysical and farm systems modelling.

PubMed

Vogeler, Iris; Mackay, Alec; Vibart, Ronaldo; Rendel, John; Beautrais, Josef; Dennis, Samuel

2016-09-15

Farm system and nutrient budget models are increasingly being used in analysis to inform on farm decision making and evaluate land use policy options at regional scales. These analyses are generally based on the use of average annual pasture yields. In New Zealand (NZ), like in many countries, there is considerable inter-annual variation in pasture growth rates, due to climate. In this study a modelling approach was used to (i) include inter-annual variability as an integral part of the analysis and (ii) test the approach in an economic analysis of irrigation in a case study within the Hawkes Bay Region of New Zealand. The Agricultural Production Systems Simulator (APSIM) was used to generate pasture dry matter yields (DMY) for 20 different years and under both dryland and irrigation. The generated DMY were linked to outputs from farm-scale modelling for both Sheep and Beef Systems (Farmaxx Pro) and Dairy Systems (Farmax® Dairy Pro) to calculate farm production over 20 different years. Variation in DMY and associated livestock production due to inter-annual variation in climate was large, with a coefficient of variations up to 20%. Irrigation decreased this inter-annual variation. On average irrigation, with unlimited available water, increased income by $831 to 1195/ha, but when irrigation was limited to 250mm/ha/year income only increased by $525 to 883/ha. Using pasture responses in individual years to capturing the inter-annual variation, rather than the pasture response averaged over 20years resulted in lower financial benefits. In the case study income from irrigation based on an average year were 10 to >20% higher compared with those obtained from individual years. Copyright © 2016 Elsevier B.V. All rights reserved.

Characterization of Regional Left Ventricular Function in Nonhuman Primates Using Magnetic Resonance Imaging Biomarkers: A Test-Retest Repeatability and Inter-Subject Variability Study

PubMed Central

Sampath, Smita; Klimas, Michael; Feng, Dai; Baumgartner, Richard; Manigbas, Elaine; Liang, Ai-Leng; Evelhoch, Jeffrey L.; Chin, Chih-Liang

2015-01-01

Pre-clinical animal models are important to study the fundamental biological and functional mechanisms involved in the longitudinal evolution of heart failure (HF). Particularly, large animal models, like nonhuman primates (NHPs), that possess greater physiological, biochemical, and phylogenetic similarity to humans are gaining interest. To assess the translatability of these models into human diseases, imaging biomarkers play a significant role in non-invasive phenotyping, prediction of downstream remodeling, and evaluation of novel experimental therapeutics. This paper sheds insight into NHP cardiac function through the quantification of magnetic resonance (MR) imaging biomarkers that comprehensively characterize the spatiotemporal dynamics of left ventricular (LV) systolic pumping and LV diastolic relaxation. MR tagging and phase contrast (PC) imaging were used to quantify NHP cardiac strain and flow. Temporal inter-relationships between rotational mechanics, myocardial strain and LV chamber flow are presented, and functional biomarkers are evaluated through test-retest repeatability and inter subject variability analyses. The temporal trends observed in strain and flow was similar to published data in humans. Our results indicate a dominant dimension based pumping during early systole, followed by a torsion dominant pumping action during late systole. Early diastole is characterized by close to 65% of untwist, the remainder of which likely contributes to efficient filling during atrial kick. Our data reveal that moderate to good intra-subject repeatability was observed for peak strain, strain-rates, E/circumferential strain-rate (CSR) ratio, E/longitudinal strain-rate (LSR) ratio, and deceleration time. The inter-subject variability was high for strain dyssynchrony, diastolic strain-rates, peak torsion and peak untwist rate. We have successfully characterized cardiac function in NHPs using MR imaging. Peak strain, average systolic strain-rate, diastolic E

A technical study of alloy compositions of "brass" wind musical instruments (1651-1867) utilizing non-destructive X-ray fluorescence

NASA Astrophysics Data System (ADS)

Bacon, Alice Louise

This thesis represents a new interdisciplinary approach to the conservation, care and curatorial study of 'brass' wind musical instruments. It attempts to combine metallurgical, chronological and historical aspects for a selection of instruments. The research consists of the systematic study of seventy-seven musical instruments, by known makers, using standardised non-destructive energy dispersive x-ray fluorescence (XRF). Such compositional data are virtually non-existent for historical 'brass' instruments in Britain and what few technical data that do exist are sporadic in quantity and quality. The development of brass instruments is interwoven with the history of brass making, but because there are a limited number of appropriate examples such links can be difficult to identify. This thesis describes the development of brass production from the cementation process to the commercial production of zinc and modern brass. Its relationship to the musical instrument industry in Britain is linked with historical evidence. It will be shown that innovation and known historical metallurgical achievements are reflected in the compositional changes of the alloys used for musical instruments. This thesis focuses on specific named brass wind musical instrument makers. This thesis sets out to investigate the extent to which a single analytical technique such as non-destructive analysis utilising XRF could be useful in the curatorial and conservation care of musical instruments. The results of the analyses revealed new aspects to the use of metals for making musical instruments. They give new information on approximate alloy compositions and, in particular, the results have shown that in the seventeenth-century in England, a ternary alloy of copper/tin/zinc was used, and that it was, perhaps, only superseded by brass (copper/zinc alloy) in the eighteenth century. It has been possible to arrange the results into a chronology of alloys particularly reflecting the change from the

42 CFR 493.1413 - Standard; Technical consultant responsibilities.

Code of Federal Regulations, 2013 CFR

2013-10-01

... consultant responsibilities. The technical consultant is responsible for the technical and scientific... of performance of instrument maintenance and function checks; (v) Assessment of test performance...

42 CFR 493.1413 - Standard; Technical consultant responsibilities.

Code of Federal Regulations, 2014 CFR

2014-10-01

... consultant responsibilities. The technical consultant is responsible for the technical and scientific... of performance of instrument maintenance and function checks; (v) Assessment of test performance...

Inter-individual variability and genetic influences on cytokine responses against bacterial and fungal pathogens

PubMed Central

Li, Yang; Oosting, Marije; Deelen, Patrick; Ricaño-Ponce, Isis; Smeekens, Sanne; Jaeger, Martin; Matzaraki, Vasiliki; Swertz, Morris A.; Xavier, Ramnik J.; Franke, Lude; Wijmenga, Cisca; Joosten, Leo A.B.; Kumar, Vinod; Netea, Mihai G.

2016-01-01

Little is known about the inter-individual variation of cytokine responses to different pathogens in healthy individuals. To systematically describe cytokine responses elicited by distinct pathogens, and to determine the impact of genetic variation on cytokine production, we profiled cytokines produced by peripheral blood mononuclear cells from 197 individuals of European origin from the 200 Functional Genomics (200FG) cohort within the Human Functional Genomics Study (www.humanfunctionalgenomics.org), obtained over three different years. By comparing bacteria- and fungi-induced cytokine profiles, we show that most cytokine responses are organized around a physiological response to specific pathogens, rather than around a particular immune pathway or cytokine. We then correlated genome-wide SNP genotypes with cytokine abundance and identified six cytokine QTLs. Among them, a cytokine QTL at NAA35-GOLM1 locus markedly modulates IL-6 production in response to multiple pathogens, and associated with susceptibility to candidemia. Furthermore, the cytokine QTLs we identified are enriched among SNPs previously associated with infectious diseases and heart diseases. These data reveal and begin to explain the variability in cytokine production by human immune cells in response to pathogens. PMID:27376574

Performance and technical commissioning of an ultra-stable cooling system for a mid-range cryogenic astrophysical instrument (CARMENES-NIR)

NASA Astrophysics Data System (ADS)

Becerril, S.; Mirabet, E.; Lizon, J. L.; Calvo, R.; Abril, M.; Cárdenas, C.; Ferro, I.; Morales, R.; Pérez, D.; Ramón, A.; Sánchez-Carrasco, M. A.; Quirrenbach, A.; Amado, P.; Ribas, I.; Reiners, A.; Caballero, J. A.; Seifert, W.; Herranz, J.

2017-12-01

CARMENES is the new high-resolution high-stability spectrograph built for the 3.5m telescope at the Calar Alto Observatory (CAHA, Almería, Spain) by a consortium formed by German and Spanish institutions. This instrument is composed of two separate spectrographs, VIS channel (550-1050 nm) and NIR channel (900-1700 nm). The Instituto de Astrofísica de Andalucía, IAA-CSIC was responsible for the NIR-channel spectrograph. This was installed at the telescope by the end of 2015, technical commissioning and final tuning of the instrument being extended up to fall 2016. In that sense, one of the most challenging systems in the instrument involves the cooling system of the NIR channel. It is a key system within the stability budget and was entirely under the control of the IAA-CSIC. That development has been possible thanks to a very fruitful collaboration with ESO (Jean-Louis Lizon). The present work describes the performance of the CARMENES-NIR cooling system, mainly focusing on the extremely high thermal stability -on the order of few cK-around the working temperature (138K), as well as the main events and upgrades achieved during commissioning. As a result of its performance, CARMENES-NIR is a cornerstone within the field of astrophysical instrumentation and, in particular, related to discovery of earth-like exoplanets.

Inter-Korean military confidence building after 2003.

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

Tae-woo, Kim; Littlefield, Adriane C.; Vannoni, Michael Geoffrey

2003-08-01

Tensions on the Korean Peninsula remain high despite a long-term strategy by South Korea to increase inter-Korean exchanges in economics, culture, sports, and other topics. This is because the process of reconciliation has rarely extended to military and security topics and those initiatives that were negotiated have been ineffective. Bilateral interactions must include actions to reduce threats and improve confidence associated with conventional military forces (land, sea, and air) as well as nuclear, chemical, and biological activities that are applicable to developing and producing weapons of mass destruction (WMD). The purpose of this project is to develop concepts for inter-Koreanmore » confidence building measures (CBMs) for military and WMD topics that South Korea could propose to the North when conditions are right. This report describes the historical and policy context for developing security-related CBMs and presents an array of bilateral options for conventional military and WMD topics within a consistent framework. The conceptual CBMs address two scenarios: (1) improved relations where construction of a peace regime becomes a full agenda item in inter-Korean dialogue, and (2) continued tense inter-Korean relations. Some measures could be proposed in the short term under current conditions, others might be implemented in a series of steps, while some require a higher level of cooperation than currently exists. To support decision making by political leaders, this research focuses on strategies and policy options and does not include technical details.« less

Latest technologic and surgical developments in using InterStim Therapy for sacral neuromodulation: impact on treatment success and safety.

PubMed

Spinelli, Michele; Sievert, Karl-Dietrich

2008-12-01

This article accompanies a "surgery in motion" DVD on sacral neuromodulation (SNM) with InterStim Therapy, which visualizes the implantation of the InterStim II system. The article describes the technical and surgical developments of SNM and their impact on treatment success, safety, and patient's quality of life (QoL). Relevant literature on SNM with regard to technical changes and related clinical outcomes has been reviewed. Since its introduction in the early 1990s, SNM has proven useful in the treatment of several types of chronic urinary (and bowel) dysfunction. Recent technical improvements in devices and, in particular, the introduction of the tined lead 5 yr ago made SNM progress from an elaborate, open-surgery, general anesthesia, one-stage implant procedure to a minimally invasive, local anesthesia, percutaneous technique in two stages. The permanent tined lead implant enables a longer patient testing period (minimum of 14 d recommended) and less lead migration. This has considerably reduced technical failures and improved the success rate of the test phase; the response rate was almost doubled to approximately 80%. These improvements also affected tolerability, resulting in increased QoL for the patient. The use of the recently introduced smaller implantable neurostimulator InterStim II seems to further improve patient comfort and makes the implant procedure for the physician easier and shorter. However, this must be further addressed in clinical studies. SNM with InterStim Therapy using the tined lead offers an efficient treatment modality for patients in whom conservative treatment has failed.

Large inter-individual and intra-individual variability in the effect of perceptual load

PubMed Central

Yeshurun, Yaffa

2017-01-01

This study examined whether the recurrent difficulty to replicate results obtained with paradigms measuring distractor processing as a function of perceptual load is due to individual differences. We first reanalyzed, at the individual level, the data of eight previously reported experiments. These reanalyses revealed substantial inter-individual differences, with particularly low percentage of participants whose performance matched the load theory’s predictions (i.e., larger distractor interference with low than high levels of load). Moreover, frequently the results were opposite to the theory's predictions–larger interference in the high than low load condition; and often a reversed compatibility effect emerged–better performance in the incompatible than neutral condition. Subsequently, seven observers participated in five identical experimental sessions. If the observed inter-individual differences are due to some stable trait or perceptual capacity, similar results should have emerged in all sessions of a given participant. However, all seven participants showed large between-sessions variations with similar patterns to those found between participants. These findings question the theoretical foundation implemented with these paradigms, as none of the theories suggested thus far can account for such inter- and intra-individual differences. Thus, these paradigms should be used with caution until further research will provide better understanding of what they actually measure. PMID:28406997

Radiographic technical quality of root canal treatment performed ex vivo by dental students at Valencia University Medical and Dental School, Spain

PubMed Central

Faus-Matoses, Vicente; Alegre-Domingo, Teresa; Faus-Llácer, Vicente J.

2014-01-01

Objectives: To evaluate radiographically the quality of root canal fillings and compare manual and rotary preparation performed on extracted teeth by undergraduate dental students. Study Design: A total of 561 premolars and molars extracted teeth were prepared using nickel-titanium rotary files or manual instrumentation and filled with gutta-percha using a cold lateral condensation technique, by 4th grade undergraduate students. Periapical radiographs were used to assess the technical quality of the root canal filling, evaluating three variables: length, density and taper. These data were recorded, scored and used to study the “technical success rate” and the “overall score”. The length of each root canal filling was classified as acceptable, short and overfilled, based on their relationship with the radiographic apex. Density and taper of filling were evaluated based on the presence of voids and the uniform tapering of the filling, respectively. Statistical analysis was used to evaluate the quality of root canal treatment, considering p < 0.05 as a statistical significant level. Results: The percentage of technical success was 44% and the overall score was 7.8 out of 10. Technical success and overall score were greater with rotary instruments (52% against 28% with a manual one, p < 0.001; 8.3 against 6.7 respectively, p < 0.001). Conclusions: It appears that inexperienced operators perform better root canal treatment (RCT) with the use of rotary instrumentation. Key words:Dental education, endodontics, rotary instrumentation, radiographs, root canal treatment, undergraduate students. PMID:24121911

Variability in bimanual wheelchair propulsion: consistency of two instrumented wheels during handrim wheelchair propulsion on a motor driven treadmill.

PubMed

Vegter, Riemer J K; Lamoth, Claudine J; de Groot, Sonja; Veeger, Dirkjan H E J; van der Woude, Lucas H V

2013-01-29

Handrim wheelchair propulsion is a complex bimanual motor task. The bimanually applied forces on the rims determine the speed and direction of locomotion. Measurements of forces and torques on the handrim are important to study status and change of propulsion technique (and consequently mechanical strain) due to processes of learning, training or the wheelchair configuration. The purpose of this study was to compare the simultaneous outcomes of two different measurement-wheels attached to the different sides of the wheelchair, to determine measurement consistency within and between these wheels given the expected inter- and intra-limb variability as a consequence of motor control. Nine able-bodied subjects received a three-week low-intensity handrim wheelchair practice intervention. They then performed three four-minute trials of wheelchair propulsion in an instrumented hand rim wheelchair on a motor-driven treadmill at a fixed belt speed. The two measurement-wheels on each side of the wheelchair measured forces and torques of one of the two upper limbs, which simultaneously perform the push action over time. The resulting data were compared as direct output using cross-correlation on the torque around the wheel-axle. Calculated push characteristics such as power production and speed were compared using an intra-class correlation. Measured torque around the wheel axle of the two measurement-wheels had a high average cross-correlation of 0.98 (std=0.01). Unilateral mean power output over a minute was found to have an intra-class correlation of 0.89 between the wheels. Although the difference over the pushes between left and right power output had a high variability, the mean difference between the measurement-wheels was low at 0.03 W (std=1.60). Other push characteristics showed even higher ICC's (>0.9). A good agreement between both measurement-wheels was found at the level of the power output. This indicates a high comparability of the measurement-wheels for the

Aeronautic Instruments. Section II : Altitude Instruments

NASA Technical Reports Server (NTRS)

Mears, A H; Henrickson, H B; Brombacher, W G

1923-01-01

This report is Section two of a series of reports on aeronautic instruments (Technical Report nos. 125 to 132, inclusive). This section discusses briefly barometric altitude determinations, and describes in detail the principal types of altimeters and barographs used in aeronautics during the recent war. This is followed by a discussion of performance requirements for such instruments and an account of the methods of testing developed by the Bureau of Standards. The report concludes with a brief account of the results of recent investigations. For accurate measurements of altitude, reference must also be made to thermometer readings of atmospheric temperature, since the altitude is not fixed by atmospheric pressure alone. This matter is discussed in connection with barometric altitude determination.

Comparison of the trunk-pelvis and lower extremities sagittal plane inter-segmental coordination and variability during walking in persons with and without chronic low back pain.

PubMed

Ebrahimi, Samaneh; Kamali, Fahimeh; Razeghi, Mohsen; Haghpanah, Seyyed Arash

2017-04-01

Inter-segmental coordination can be influenced by chronic low back pain (CLBP). The sagittal plane lower extremities inter-segmental coordination pattern and variability, in conjunction with the pelvis and trunk, were assessed in subjects with and without non-specific CLBP during free-speed walking. Kinematic data were collected from 10 non-specific CLBP and 10 non-CLBP control volunteers while the subjects were walking at their preferred speed. Sagittal plane time-normalized segmental angles and velocities were used to calculate continuous relative phase for each data point. Mean absolute relative phase (MARP) and deviation phase (DP) were derived to quantify the trunk-pelvis and bilateral pelvis-thigh, thigh-shank and shank-foot coordination pattern and variability over the stance and swing phases of gait. Mann-Whitney U test was employed to compare the means of DP and MARP values between two groups (same side comparison). Statistical analysis revealed more in-phase/less variable trunk-pelvis coordination in the CLBP group (P<0.05). CLBP group demonstrated less variable right or left pelvis-thigh coordination pattern (P<0.05). Moreover, the left thigh-shank and left shank-foot MARP values in the CLBP group, were more in-phase than left MARP values in the non-CLBP control group during the swing phase (P<0.05). In conclusion, the sagittal plane lower extremities, pelvis and trunk coordination pattern and variability could be generally affected by CLBP during walking. These changes can be possible compensatory strategies of the motor control system which can be considered in the CLBP subjects. Copyright © 2017 Elsevier B.V. All rights reserved.

Do Two or More Multicomponent Instruments Measure the Same Construct? Testing Construct Congruence Using Latent Variable Modeling

ERIC Educational Resources Information Center

Raykov, Tenko; Marcoulides, George A.; Tong, Bing

2016-01-01

A latent variable modeling procedure is discussed that can be used to test if two or more homogeneous multicomponent instruments with distinct components are measuring the same underlying construct. The method is widely applicable in scale construction and development research and can also be of special interest in construct validation studies.…

Inter- and intra-species variability in heat resistance and the effect of heat treatment intensity on subsequent growth of Byssochlamys fulva and Byssochlamys nivea.

PubMed

Santos, Juliana L P; Samapundo, Simbarashe; Gülay, Sonay M; Van Impe, Jan; Sant'Ana, Anderson S; Devlieghere, Frank

2018-04-21

The major aims of this study were to assess inter- and intra-species variability of heat resistant moulds (HRMs), Byssochlamys fulva and Byssochlamys nivea, with regards to (i) heat resistance and (ii) effect of heat treatment intensity on subsequent outgrowth. Four-week-old ascospores were suspended in buffered glucose solution (13° Brix, pH 3.5) and heat treated in a thermal cycler adjusted at 85 °C, 90 °C and 93 °C. Two variants of the Weibull model were fitted to the survival data and the following inactivation parameters estimated: b (inactivation rate, min -1 ), n (curve shape) and δ (the time taken for first decimal reduction, min). In addition to the assessment of heat resistance, outgrowth of Byssochlamys sp. from ascospores heated at 70 °C, 75 °C, 80 °C, 85 °C and 90 °C for 10 min and at 93 °C for 30 and 70 s was determined at 22 °C for up to 30 days. The Baranyi and Roberts model was fitted to the growth data to estimate the radial growth rates (μ max , mm.day -1 ) and lag times (λ, days). Inter-species variability and significant differences (p < 0.05) were observed for both inactivation and growth estimated parameters among B. fulva and B. nivea strains. The effect of heat treatment intensity on outgrowth of B. fulva strains was more apparent at the most intense heat treatment evaluated (90 °C/10 min), which was also the condition in which greater dispersion of the estimated kinetic parameters was observed. On the other hand, B. nivea strains were more affected by heating, resulting in greater variability of growth parameters estimated at different heating intensities and in very long lag phases (up to 25 days). The results show that inter- and intra-species variability in the kinetic parameters of Byssochlamys sp. needs to be taken into account for more accurate spoilage prediction. Furthermore, the effect of thermal treatments on subsequent outgrowth from ascospores should be explored in

Influence of seasonal and inter-annual hydro-meteorological variability on surface water fecal coliform concentration under varying land-use composition.

PubMed

St Laurent, Jacques; Mazumder, Asit

2014-01-01

Quantifying the influence of hydro-meteorological variability on surface source water fecal contamination is critical to the maintenance of safe drinking water. Historically, this has not been possible due to the scarcity of data on fecal indicator bacteria (FIB). We examined the relationship between hydro-meteorological variability and the most commonly measured FIB, fecal coliform (FC), concentration for 43 surface water sites within the hydro-climatologically complex region of British Columbia. The strength of relationship was highly variable among sites, but tended to be stronger in catchments with nival (snowmelt-dominated) hydro-meteorological regimes and greater land-use impacts. We observed positive relationships between inter-annual FC concentration and hydro-meteorological variability for around 50% of the 19 sites examined. These sites are likely to experience increased fecal contamination due to the projected intensification of the hydrological cycle. Seasonal FC concentration variability appeared to be driven by snowmelt and rainfall-induced runoff for around 30% of the 43 sites examined. Earlier snowmelt in nival catchments may advance the timing of peak contamination, and the projected decrease in annual snow-to-precipitation ratio is likely to increase fecal contamination levels during summer, fall, and winter among these sites. Safeguarding drinking water quality in the face of such impacts will require increased monitoring of FIB and waterborne pathogens, especially during periods of high hydro-meteorological variability. This data can then be used to develop predictive models, inform source water protection measures, and improve drinking water treatment. Copyright © 2013 Elsevier Ltd. All rights reserved.

Climate drives inter-annual variability in probability of high severity fire occurrence in the western United States

NASA Astrophysics Data System (ADS)

Keyser, Alisa; Westerling, Anthony LeRoy

2017-05-01

A long history of fire suppression in the western United States has significantly changed forest structure and ecological function, leading to increasingly uncharacteristic fires in terms of size and severity. Prior analyses of fire severity in California forests showed that time since last fire and fire weather conditions predicted fire severity very well, while a larger regional analysis showed that topography and climate were important predictors of high severity fire. There has not yet been a large-scale study that incorporates topography, vegetation and fire-year climate to determine regional scale high severity fire occurrence. We developed models to predict the probability of high severity fire occurrence for the western US. We predict high severity fire occurrence with some accuracy, and identify the relative importance of predictor classes in determining the probability of high severity fire. The inclusion of both vegetation and fire-year climate predictors was critical for model skill in identifying fires with high fractional fire severity. The inclusion of fire-year climate variables allows this model to forecast inter-annual variability in areas at future risk of high severity fire, beyond what slower-changing fuel conditions alone can accomplish. This allows for more targeted land management, including resource allocation for fuels reduction treatments to decrease the risk of high severity fire.

Ocean Observation Instrument

NASA Technical Reports Server (NTRS)

1993-01-01

The Airborne Ocean Color Imager (AOCI) was developed by Daedalus Enterprises, Inc. for Ames Research Center under a Small Business Innovation Research (SBIR) contract as a simulator for an advanced oceanographic satellite instrument. The instrument measures water temperature and detects water color in nine wavelengths. Water color indicates chlorophyll content or phytoplankton. After EOCAP assistance and technical improvements, the AOCI was successfully commercialized by Daedalus Enterprises, Inc. One version provides commercial fishing fleets with information about fish locations, and the other is used for oceanographic research.

Interannual variability of mean sea level and its sensitivity to wind climate in an inter-tidal basin

NASA Astrophysics Data System (ADS)

Gerkema, Theo; Duran-Matute, Matias

2017-12-01

The relationship between the annual wind records from a weather station and annual mean sea level in an inter-tidal basin, the Dutch Wadden Sea, is examined. Recent, homogeneous wind records are used, covering the past 2 decades. It is demonstrated that even such a relatively short record is sufficient for finding a convincing relationship. The interannual variability of mean sea level is largely explained by the west-east component of the net wind energy, with some further improvement if one also includes the south-north component and the annual mean atmospheric pressure. Using measured data from a weather station is found to give a slight improvement over reanalysis data, but for both the correlation between annual mean sea level and wind energy in the west-east direction is high. For different tide gauge stations in the Dutch Wadden Sea and along the coast, we find the same qualitative characteristics, but even within this small region, different locations show a different sensitivity of annual mean sea level to wind direction. Correcting observed values of annual mean level for meteorological factors reduces the margin of error (expressed as 95 % confidence interval) by more than a factor of 4 in the trends of the 20-year sea level record. Supplementary data from a numerical hydrodynamical model are used to illustrate the regional variability in annual mean sea level and its interannual variability at a high spatial resolution. This study implies that climatic changes in the strength of winds from a specific direction may affect local annual mean sea level quite significantly.

Inter- and Intra-individual variability following intermittent theta burst stimulation: implications for rehabilitation and recovery.

PubMed

Hinder, Mark R; Goss, Emily L; Fujiyama, Hakuei; Canty, Alison J; Garry, Michael I; Rodger, Jennifer; Summers, Jeffery J

2014-01-01

The continued refinement of non-invasive brain stimulation (NBS) techniques is indicative of promising clinical and rehabilitative interventions that are able to modulate cortical excitability. Intermittent theta burst stimulation (iTBS) is one such technique that can increase cortical excitability, purportedly via LTP-like mechanisms. While iTBS may have the capacity to promote recovery after neurological injury, and to combat cognitive and motor decline, recent reports observed highly variable effects across individuals, questioning the efficacy of iTBS as a clinical tool. The aim of this study was to examine intra-individual reliability and inter-individual variability in responses to iTBS. Thirty healthy participants completed two experimental sessions of the iTBS protocol 1-3 weeks apart. Motor evoked potentials in response to single pulse TMS were used to assess corticospinal excitability prior to, and up to 36 min following, iTBS. At the group level, iTBS evoked statistically significant increases in motor cortical excitability across both sessions (P < 0.001), with 22 out of 30 participants exhibiting increases in excitability in both sessions. A strong intraclass correlation demonstrated that both the direction, and magnitude of the plastic changes were reliable at the individual level. Overall, our results suggest that iTBS is capable of inducing relatively robust and consistent effects within and between young individuals. As such, the capacity for iTBS to be exploited in clinical and rehabilitative interventions should continue to be explored. Copyright © 2014 Elsevier Inc. All rights reserved.

Instrumental variable applications using nursing home prescribing preferences in comparative effectiveness research.

PubMed

Huybrechts, Krista F; Gerhard, Tobias; Franklin, Jessica M; Levin, Raisa; Crystal, Stephen; Schneeweiss, Sebastian

2014-08-01

Nursing home residents are of particular interest for comparative effectiveness research given their susceptibility to adverse treatment effects and systematic exclusion from trials. However, the risk of residual confounding because of unmeasured markers of declining health using conventional analytic methods is high. We evaluated the validity of instrumental variable (IV) methods based on nursing home prescribing preference to mitigate such confounding, using psychotropic medications to manage behavioral problems in dementia as a case study. A cohort using linked data from Medicaid, Medicare, Minimum Data Set, and Online Survey, Certification and Reporting for 2001-2004 was established. Dual-eligible patients ≥65 years who initiated psychotropic medication use after admission were selected. Nursing home prescribing preference was characterized using mixed-effects logistic regression models. The plausibility of IV assumptions was explored, and the association between psychotropic medication class and 180-day mortality was estimated. High-prescribing and low-prescribing nursing homes differed by a factor of 2. Each preference-based IV measure described a substantial proportion of variation in psychotropic medication choice (β(IV → treatment): 0.22-0.36). Measured patient characteristics were well balanced across patient groups based on instrument status (52% average reduction in Mahalanobis distance). There was no evidence that instrument status was associated with markers of nursing home quality of care. Findings indicate that IV analyses using nursing home prescribing preference may be a useful approach in comparative effectiveness studies, and should extend naturally to analyses including untreated comparison groups, which are of great scientific interest but subject to even stronger confounding. Copyright © 2014 John Wiley & Sons, Ltd.

Association of Body Mass Index with Depression, Anxiety and Suicide—An Instrumental Variable Analysis of the HUNT Study

PubMed Central

Bjørngaard, Johan Håkon; Carslake, David; Lund Nilsen, Tom Ivar; Linthorst, Astrid C. E.; Davey Smith, George; Gunnell, David; Romundstad, Pål Richard

2015-01-01

Objective While high body mass index is associated with an increased risk of depression and anxiety, cumulative evidence indicates that it is a protective factor for suicide. The associations from conventional observational studies of body mass index with mental health outcomes are likely to be influenced by reverse causality or confounding by ill-health. In the present study, we investigated the associations between offspring body mass index and parental anxiety, depression and suicide in order to avoid problems with reverse causality and confounding by ill-health. Methods We used data from 32,457 mother-offspring and 27,753 father-offspring pairs from the Norwegian HUNT-study. Anxiety and depression were assessed using the Hospital Anxiety and Depression Scale and suicide death from national registers. Associations between offspring and own body mass index and symptoms of anxiety and depression and suicide mortality were estimated using logistic and Cox regression. Causal effect estimates were estimated with a two sample instrument variable approach using offspring body mass index as an instrument for parental body mass index. Results Both own and offspring body mass index were positively associated with depression, while the results did not indicate any substantial association between body mass index and anxiety. Although precision was low, suicide mortality was inversely associated with own body mass index and the results from the analysis using offspring body mass index supported these results. Adjusted odds ratios per standard deviation body mass index from the instrumental variable analysis were 1.22 (95% CI: 1.05, 1.43) for depression, 1.10 (95% CI: 0.95, 1.27) for anxiety, and the instrumental variable estimated hazard ratios for suicide was 0.69 (95% CI: 0.30, 1.63). Conclusion The present study’s results indicate that suicide mortality is inversely associated with body mass index. We also found support for a positive association between body mass index

Association of Body Mass Index with Depression, Anxiety and Suicide-An Instrumental Variable Analysis of the HUNT Study.

PubMed

Bjørngaard, Johan Håkon; Carslake, David; Lund Nilsen, Tom Ivar; Linthorst, Astrid C E; Davey Smith, George; Gunnell, David; Romundstad, Pål Richard

2015-01-01

While high body mass index is associated with an increased risk of depression and anxiety, cumulative evidence indicates that it is a protective factor for suicide. The associations from conventional observational studies of body mass index with mental health outcomes are likely to be influenced by reverse causality or confounding by ill-health. In the present study, we investigated the associations between offspring body mass index and parental anxiety, depression and suicide in order to avoid problems with reverse causality and confounding by ill-health. We used data from 32,457 mother-offspring and 27,753 father-offspring pairs from the Norwegian HUNT-study. Anxiety and depression were assessed using the Hospital Anxiety and Depression Scale and suicide death from national registers. Associations between offspring and own body mass index and symptoms of anxiety and depression and suicide mortality were estimated using logistic and Cox regression. Causal effect estimates were estimated with a two sample instrument variable approach using offspring body mass index as an instrument for parental body mass index. Both own and offspring body mass index were positively associated with depression, while the results did not indicate any substantial association between body mass index and anxiety. Although precision was low, suicide mortality was inversely associated with own body mass index and the results from the analysis using offspring body mass index supported these results. Adjusted odds ratios per standard deviation body mass index from the instrumental variable analysis were 1.22 (95% CI: 1.05, 1.43) for depression, 1.10 (95% CI: 0.95, 1.27) for anxiety, and the instrumental variable estimated hazard ratios for suicide was 0.69 (95% CI: 0.30, 1.63). The present study's results indicate that suicide mortality is inversely associated with body mass index. We also found support for a positive association between body mass index and depression, but not for anxiety.

Content validity of the Geriatric Health Assessment Instrument

PubMed Central

Pedreira, Rhaine Borges Santos; Rocha, Saulo Vasconcelos; dos Santos, Clarice Alves; Vasconcelos, Lélia Renata Carneiro; Reis, Martha Cerqueira

2016-01-01

ABSTRACT Objective Assess the content validity of the Elderly Health Assessment Tool with low education. Methods The data collection instrument/questionnaire was prepared and submitted to an expert panel comprising four healthcare professionals experienced in research on epidemiology of aging. The experts were allowed to suggest item inclusion/exclusion and were asked to rate the ability of individual items in questionnaire blocks to encompass target dimensions as “not valid”, “somewhat valid” or “valid”, using an interval scale. Percent agreement and the Content Validity Index were used as measurements of inter-rater agreement; the minimum acceptable inter-rater agreement was set at 80%. Results The mean instrument percent agreement rate was 86%, ranging from 63 to 99%, and from 50 to 100% between and within blocks respectively. The Mean Content Validity Index score was 93.47%, ranging from 50 to 100% between individual items. Conclusion The instrument showed acceptable psychometric properties for application in geriatric populations with low levels of education. It enabled identifying diseases and assisted in choice of strategies related to health of the elderly. PMID:27462889

Mixed effects versus fixed effects modelling of binary data with inter-subject variability.

PubMed

Murphy, Valda; Dunne, Adrian

2005-04-01

The question of whether or not a mixed effects model is required when modelling binary data with inter-subject variability and within subject correlation was reported in this journal by Yano et al. (J. Pharmacokin. Pharmacodyn. 28:389-412 [2001]). That report used simulation experiments to demonstrate that, under certain circumstances, the use of a fixed effects model produced more accurate estimates of the fixed effect parameters than those produced by a mixed effects model. The Laplace approximation to the likelihood was used when fitting the mixed effects model. This paper repeats one of those simulation experiments, with two binary observations recorded for every subject, and uses both the Laplace and the adaptive Gaussian quadrature approximations to the likelihood when fitting the mixed effects model. The results show that the estimates produced using the Laplace approximation include a small number of extreme outliers. This was not the case when using the adaptive Gaussian quadrature approximation. Further examination of these outliers shows that they arise in situations in which the Laplace approximation seriously overestimates the likelihood in an extreme region of the parameter space. It is also demonstrated that when the number of observations per subject is increased from two to three, the estimates based on the Laplace approximation no longer include any extreme outliers. The root mean squared error is a combination of the bias and the variability of the estimates. Increasing the sample size is known to reduce the variability of an estimator with a consequent reduction in its root mean squared error. The estimates based on the fixed effects model are inherently biased and this bias acts as a lower bound for the root mean squared error of these estimates. Consequently, it might be expected that for data sets with a greater number of subjects the estimates based on the mixed effects model would be more accurate than those based on the fixed effects model

THE EFFECT OF FEEDBACK ON THE ACCURACY OF CHECKLIST COMPLETION DURING INSTRUMENT FLIGHT TRAINING

PubMed Central

Rantz, William G; Dickinson, Alyce M; Sinclair, Gilbert A; Van Houten, Ron

2009-01-01

This study examined whether pilots completed airplane checklists more accurately when they receive postflight graphic and verbal feedback. Participants were 8 college students who are pilots with an instrument rating. The task consisted of flying a designated flight pattern using a personal computer aviation training device (PCATD). The dependent variables were the number of checklist items completed correctly. A multiple baseline design across pairs of participants with withdrawal of treatment was employed in this study. During baseline, participants were given postflight technical feedback. During intervention, participants were given postflight graphic feedback on checklist use and praise for improvements along with technical feedback. The intervention produced near perfect checklist performance, which was maintained following a return to the baseline conditions. PMID:20190914

Robust best linear estimator for Cox regression with instrumental variables in whole cohort and surrogates with additive measurement error in calibration sample.

PubMed

Wang, Ching-Yun; Song, Xiao

2016-11-01

Biomedical researchers are often interested in estimating the effect of an environmental exposure in relation to a chronic disease endpoint. However, the exposure variable of interest may be measured with errors. In a subset of the whole cohort, a surrogate variable is available for the true unobserved exposure variable. The surrogate variable satisfies an additive measurement error model, but it may not have repeated measurements. The subset in which the surrogate variables are available is called a calibration sample. In addition to the surrogate variables that are available among the subjects in the calibration sample, we consider the situation when there is an instrumental variable available for all study subjects. An instrumental variable is correlated with the unobserved true exposure variable, and hence can be useful in the estimation of the regression coefficients. In this paper, we propose a nonparametric method for Cox regression using the observed data from the whole cohort. The nonparametric estimator is the best linear combination of a nonparametric correction estimator from the calibration sample and the difference of the naive estimators from the calibration sample and the whole cohort. The asymptotic distribution is derived, and the finite sample performance of the proposed estimator is examined via intensive simulation studies. The methods are applied to the Nutritional Biomarkers Study of the Women's Health Initiative. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Robust best linear estimator for Cox regression with instrumental variables in whole cohort and surrogates with additive measurement error in calibration sample

PubMed Central

Wang, Ching-Yun; Song, Xiao

2017-01-01

SUMMARY Biomedical researchers are often interested in estimating the effect of an environmental exposure in relation to a chronic disease endpoint. However, the exposure variable of interest may be measured with errors. In a subset of the whole cohort, a surrogate variable is available for the true unobserved exposure variable. The surrogate variable satisfies an additive measurement error model, but it may not have repeated measurements. The subset in which the surrogate variables are available is called a calibration sample. In addition to the surrogate variables that are available among the subjects in the calibration sample, we consider the situation when there is an instrumental variable available for all study subjects. An instrumental variable is correlated with the unobserved true exposure variable, and hence can be useful in the estimation of the regression coefficients. In this paper, we propose a nonparametric method for Cox regression using the observed data from the whole cohort. The nonparametric estimator is the best linear combination of a nonparametric correction estimator from the calibration sample and the difference of the naive estimators from the calibration sample and the whole cohort. The asymptotic distribution is derived, and the finite sample performance of the proposed estimator is examined via intensive simulation studies. The methods are applied to the Nutritional Biomarkers Study of the Women’s Health Initiative. PMID:27546625

Instruments speak global language

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

Nudo, L.

1993-07-01

If all goes as planned, companies that use instruments for measurement and control will get more complete, reliable and repeatable information about their processes with advanced digital devices that speak a global language. That language, in technical terms, is known as international fieldbus. But it's not much different from English's role as the international language of business. Companies that use a remote measurement device for environmental applications, such as pH control and fugitive emissions control, are candidates for fieldbus devices, which are much faster and measure more process variables than their counterpart analog devices. With the advent of a globalmore » fieldbus, users will see digital valves, solenoids and multivariable transmitters. Fieldbus technology redefines the roles of the control system and field devices. The control system still serves as a central clearinghouse, but field devices will handle more control and reporting functions and generate data that can be used for trending and preventive maintenance.« less

Analysis of the contribution of experimental bias, experimental noise, and inter-subject biological variability on the assessment of developmental trajectories in diffusion MRI studies of the brain.

PubMed

Sadeghi, Neda; Nayak, Amritha; Walker, Lindsay; Okan Irfanoglu, M; Albert, Paul S; Pierpaoli, Carlo

2015-04-01

Metrics derived from the diffusion tensor, such as fractional anisotropy (FA) and mean diffusivity (MD) have been used in many studies of postnatal brain development. A common finding of previous studies is that these tensor-derived measures vary widely even in healthy populations. This variability can be due to inherent inter-individual biological differences as well as experimental noise. Moreover, when comparing different studies, additional variability can be introduced by different acquisition protocols. In this study we examined scans of 61 individuals (aged 4-22 years) from the NIH MRI study of normal brain development. Two scans were collected with different protocols (low and high resolution). Our goal was to separate the contributions of biological variability and experimental noise to the overall measured variance, as well as to assess potential systematic effects related to the use of different protocols. We analyzed FA and MD in seventeen regions of interest. We found that biological variability for both FA and MD varies widely across brain regions; biological variability is highest for FA in the lateral part of the splenium and body of the corpus callosum along with the cingulum and the superior longitudinal fasciculus, and for MD in the optic radiations and the lateral part of the splenium. These regions with high inter-individual biological variability are the most likely candidates for assessing genetic and environmental effects in the developing brain. With respect to protocol-related effects, the lower resolution acquisition resulted in higher MD and lower FA values for the majority of regions compared with the higher resolution protocol. However, the majority of the regions did not show any age-protocol interaction, indicating similar trajectories were obtained irrespective of the protocol used. Published by Elsevier Inc.

Technical quality of a matching-taper single-cone filling technique following rotary instrumentation compared with lateral compaction after manual preparation: a retrospective study.

PubMed

Krug, R; Krastl, G; Jahreis, M

2017-03-01

The objectives of the study were to evaluate the radiographic technical quality of root canal treatment before and after the implementation of a nickel-titanium rotary (NiTiR) preparation followed by a matching-taper single-cone (mSC) obturation and to detect the procedural errors associated with this technique. A random sample of 535 patients received root canal treatment at the Department of Conservative Dentistry and Periodontology at the University of Würzburg: 254 teeth were treated in 2002-2003 by using stainless steel instruments (SSI) for preparation and a lateral compaction (LC) technique (classic group (CG)). Two hundred eighty-one teeth were root filled in 2012-2013 employing NiTiR instruments for the root canal shaping and a mSC technique (advanced group (AG)). The quality assessments were based on the radiographic criteria of the European Society of Endodontology. The presence of voids was recorded separately for the apical, central and cervical thirds of the root canals. Procedural errors, such as ledges, apical transportations, perforations and fractured instruments, were detected. The root canal fillings in the CG and AG were compared using chi-squared and Fisher's exact tests. Multivariable logistic regression was performed to investigate the association between the independent variables (patient age, tooth type and type of treatment) and the dependent variables (density and length). Adequate length was achieved significantly more often in the AG compared to the CG for molars (p = 0.017), mandibular teeth (p = 0.013) and primary root canal treatments (p = 0.024). No significant difference was detected between the AG and CG regarding adequate length in general (p = 0.051) or adequate overall quality of root canal filling (p = 0.1). In the AG, a significant decrease in procedural errors was evident (p = 0.019) and decreases in the densities of the root canal fillings in the cervical (p = 0.01) and central (p = 0.01) thirds of the

Evaluating the effectiveness of case method instruction in technical communication

NASA Technical Reports Server (NTRS)

Feinberg, S. G.

1981-01-01

The effectiveness of the case method as an instructional technique in improving technical writing was evaluated. The development of a self-report instrument that attempts to measure changes in attitude toward technical communication and the presentation results change are the purpose of this paper. Standards for developing a case set forth by Goldstein and Couture, were used to design an evaluation instrument to measure the effect instruction on student attitude toward technical communication. This self-report instrument is based on model developed and tested by Daly and Miller who studied writer attitude and apprehension toward writing. It was the most important objective of any evaluation is to provide information for improving the program.

Instrumental Variable Methods for Continuous Outcomes That Accommodate Nonignorable Missing Baseline Values.

PubMed

Ertefaie, Ashkan; Flory, James H; Hennessy, Sean; Small, Dylan S

2017-06-15

Instrumental variable (IV) methods provide unbiased treatment effect estimation in the presence of unmeasured confounders under certain assumptions. To provide valid estimates of treatment effect, treatment effect confounders that are associated with the IV (IV-confounders) must be included in the analysis, and not including observations with missing values may lead to bias. Missing covariate data are particularly problematic when the probability that a value is missing is related to the value itself, which is known as nonignorable missingness. In such cases, imputation-based methods are biased. Using health-care provider preference as an IV method, we propose a 2-step procedure with which to estimate a valid treatment effect in the presence of baseline variables with nonignorable missing values. First, the provider preference IV value is estimated by performing a complete-case analysis using a random-effects model that includes IV-confounders. Second, the treatment effect is estimated using a 2-stage least squares IV approach that excludes IV-confounders with missing values. Simulation results are presented, and the method is applied to an analysis comparing the effects of sulfonylureas versus metformin on body mass index, where the variables baseline body mass index and glycosylated hemoglobin have missing values. Our result supports the association of sulfonylureas with weight gain. © The Author 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The Mean State and Inter-annual Variability of East Asian Summer Monsoon in CMIP5 Coupled Models: Does Air-Sea Coupling Improve the Simulations?

NASA Astrophysics Data System (ADS)

Zhou, T.; Song, F.

2014-12-01

The climatology and inter-annual variability of East Asian summer monsoon (EASM) simulated by 34 Coupled Model Intercomparison Project phase 5 (CMIP5) coupled general circulation models (CGCMs) are evaluated. To estimate the role of air-sea coupling, 17 CGCMs are compared to their corresponding atmospheric general circulation models (AGCMs). The climatological low-level monsoon circulation and mei-yu/changma/baiu rainfall band are improved in CGCMs from AGCMs. The improvement is at the cost of the local cold sea surface temperature (SST) biases in CGCMs, since they decrease the surface evaporation and enhance the circulation. The inter-annual EASM pattern is evaluated by a skill formula and the highest/lowest 8 models are selected to investigate the skill origins. The observed Indian Ocean (IO) warming, tropical eastern Indian Ocean (TEIO) rainfall anomalies and Kelvin wave response are captured well in high-skill models, while these features are not present in low-skill models. Further, the differences in the IO warming between high-skill and low-skill models are rooted in the preceding ENSO simulation. Hence, the IO-WPAC teleconnection is important for CGCMs, similar to AGCMs. However, compared to AGCMs, the easterly anomalies in the southern flank of the WPAC make the TEIO warmer in CGCMs by reducing the climatological monsoon westerlies and decreasing the surface evaporation. The warmer TEIO induces the stronger precipitation anomalies and intensifies the teleconnection. Hence, the inter-annual EASM pattern is better simulated in CGCMs than that in AGCMs. Key words: CMIP5, CGCMs, air-sea coupling, AGCMs, inter-annual EASM pattern, ENSO, IO-WPAC teleconnection

Implicit Review Instrument to Evaluate Quality of Care Delivered by Physicians to Children in Emergency Departments.

PubMed

Marcin, James P; Romano, Patrick S; Dharmar, Madan; Chamberlain, James M; Dudley, Nanette; Macias, Charles G; Nigrovic, Lise E; Powell, Elizabeth C; Rogers, Alexander J; Sonnett, Meridith; Tzimenatos, Leah; Alpern, Elizabeth R; Andrews-Dickert, Rebecca; Borgialli, Dominic A; Sidney, Erika; Casper, Charlie; Dean, Jonathan Michael; Kuppermann, Nathan

2018-06-01

To evaluate the consistency, reliability, and validity of an implicit review instrument that measures the quality of care provided to children in the emergency department (ED). Medical records of randomly selected children from 12 EDs in the Pediatric Emergency Care Applied Research Network (PECARN). Eight pediatric emergency medicine physicians applied the instrument to 620 medical records. We determined internal consistency using Cronbach's alpha and inter-rater reliability using the intraclass correlation coefficient (ICC). We evaluated the validity of the instrument by correlating scores with four condition-specific explicit review instruments. Individual reviewers' Cronbach's alpha had a mean of 0.85 with a range of 0.76-0.97; overall Cronbach's alpha was 0.90. The ICC was 0.49 for the summary score with a range from 0.40 to 0.46. Correlations between the quality of care score and the four condition-specific explicit review scores ranged from 0.24 to 0.38. The quality of care instrument demonstrated good internal consistency, moderate inter-rater reliability, high inter-rater agreement, and evidence supporting validity. The instrument could be useful for systems' assessment and research in evaluating the care delivered to children in the ED. © Health Research and Educational Trust.

The interRAI Acute Care instrument incorporated in an eHealth system for standardized and web-based geriatric assessment: strengths, weaknesses, opportunities and threats in the acute hospital setting

PubMed Central

2013-01-01

Background The interRAI Acute Care instrument is a multidimensional geriatric assessment system intended to determine a hospitalized older persons’ medical, psychosocial and functional capacity and needs. Its objective is to develop an overall plan for treatment and long-term follow-up based on a common set of standardized items that can be used in various care settings. A Belgian web-based software system (BelRAI-software) was developed to enable clinicians to interpret the output and to communicate the patients’ data across wards and care organizations. The purpose of the study is to evaluate the (dis)advantages of the implementation of the interRAI Acute Care instrument as a comprehensive geriatric assessment instrument in an acute hospital context. Methods In a cross-sectional multicenter study on four geriatric wards in three acute hospitals, trained clinical staff (nurses, occupational therapists, social workers, and geriatricians) assessed 410 inpatients in routine clinical practice. The BelRAI-system was evaluated by focus groups, observations, and questionnaires. The Strengths, Weaknesses, Opportunities and Threats were mapped (SWOT-analysis) and validated by the participants. Results The primary strengths of the BelRAI-system were a structured overview of the patients’ condition early after admission and the promotion of multidisciplinary assessment. Our study was a first attempt to transfer standardized data between home care organizations, nursing homes and hospitals and a way to centralize medical, allied health professionals and nursing data. With the BelRAI-software, privacy of data is guaranteed. Weaknesses are the time-consuming character of the process and the overlap with other assessment instruments or (electronic) registration forms. There is room for improving the user-friendliness and the efficiency of the software, which needs hospital-specific adaptations. Opportunities are a timely and systematic problem detection and continuity of

The interRAI Acute Care instrument incorporated in an eHealth system for standardized and web-based geriatric assessment: strengths, weaknesses, opportunities and threats in the acute hospital setting.

PubMed

Devriendt, Els; Wellens, Nathalie I H; Flamaing, Johan; Declercq, Anja; Moons, Philip; Boonen, Steven; Milisen, Koen

2013-09-05

The interRAI Acute Care instrument is a multidimensional geriatric assessment system intended to determine a hospitalized older persons' medical, psychosocial and functional capacity and needs. Its objective is to develop an overall plan for treatment and long-term follow-up based on a common set of standardized items that can be used in various care settings. A Belgian web-based software system (BelRAI-software) was developed to enable clinicians to interpret the output and to communicate the patients' data across wards and care organizations. The purpose of the study is to evaluate the (dis)advantages of the implementation of the interRAI Acute Care instrument as a comprehensive geriatric assessment instrument in an acute hospital context. In a cross-sectional multicenter study on four geriatric wards in three acute hospitals, trained clinical staff (nurses, occupational therapists, social workers, and geriatricians) assessed 410 inpatients in routine clinical practice. The BelRAI-system was evaluated by focus groups, observations, and questionnaires. The Strengths, Weaknesses, Opportunities and Threats were mapped (SWOT-analysis) and validated by the participants. The primary strengths of the BelRAI-system were a structured overview of the patients' condition early after admission and the promotion of multidisciplinary assessment. Our study was a first attempt to transfer standardized data between home care organizations, nursing homes and hospitals and a way to centralize medical, allied health professionals and nursing data. With the BelRAI-software, privacy of data is guaranteed. Weaknesses are the time-consuming character of the process and the overlap with other assessment instruments or (electronic) registration forms. There is room for improving the user-friendliness and the efficiency of the software, which needs hospital-specific adaptations. Opportunities are a timely and systematic problem detection and continuity of care. An actual shortage of

Instrumental variable approaches to identifying the causal effect of educational attainment on dementia risk

PubMed Central

Nguyen, Thu T.; Tchetgen Tchetgen, Eric J.; Kawachi, Ichiro; Gilman, Stephen E.; Walter, Stefan; Liu, Sze Y.; Manly, Jennifer; Glymour, M. Maria

2015-01-01

Purpose Education is an established correlate of cognitive status in older adulthood, but whether expanding educational opportunities would improve cognitive functioning remains unclear given limitations of prior studies for causal inference. Therefore, we conducted instrumental variable (IV) analyses of the association between education and dementia risk, using for the first time in this area, genetic variants as instruments as well as state-level school policies. Methods IV analyses in the Health and Retirement Study cohort (1998–2010) used two sets of instruments: 1) a genetic risk score constructed from three single nucleotide polymorphisms (SNPs) (n=8,054); and 2) compulsory schooling laws (CSLs) and state school characteristics (term length, student teacher ratios, and expenditures) (n=13,167). Results Employing the genetic risk score as an IV, there was a 1.1% reduction in dementia risk per year of schooling (95% CI: −2.4, 0.02). Leveraging compulsory schooling laws and state school characteristics as IVs, there was a substantially larger protective effect (−9.5%; 95% CI: −14.8, −4.2). Analyses evaluating the plausibility of the IV assumptions indicated estimates derived from analyses relying on CSLs provide the best estimates of the causal effect of education. Conclusion IV analyses suggest education is protective against risk of dementia in older adulthood. PMID:26633592

Analytical techniques and instrumentation: A compilation. [analytical instrumentation, materials performance, and systems analysis

NASA Technical Reports Server (NTRS)

1974-01-01

Technical information is presented covering the areas of: (1) analytical instrumentation useful in the analysis of physical phenomena; (2) analytical techniques used to determine the performance of materials; and (3) systems and component analyses for design and quality control.

Human instrumental performance in ratio and interval contingencies: A challenge for associative theory.

PubMed

Pérez, Omar D; Aitken, Michael R F; Zhukovsky, Peter; Soto, Fabián A; Urcelay, Gonzalo P; Dickinson, Anthony

2016-12-15

Associative learning theories regard the probability of reinforcement as the critical factor determining responding. However, the role of this factor in instrumental conditioning is not completely clear. In fact, free-operant experiments show that participants respond at a higher rate on variable ratio than on variable interval schedules even though the reinforcement probability is matched between the schedules. This difference has been attributed to the differential reinforcement of long inter-response times (IRTs) by interval schedules, which acts to slow responding. In the present study, we used a novel experimental design to investigate human responding under random ratio (RR) and regulated probability interval (RPI) schedules, a type of interval schedule that sets a reinforcement probability independently of the IRT duration. Participants responded on each type of schedule before a final choice test in which they distributed responding between two schedules similar to those experienced during training. Although response rates did not differ during training, the participants responded at a lower rate on the RPI schedule than on the matched RR schedule during the choice test. This preference cannot be attributed to a higher probability of reinforcement for long IRTs and questions the idea that similar associative processes underlie classical and instrumental conditioning.

Sonar Test and Test Instrumentation Support.

DTIC Science & Technology

1979-03-29

AD-AlSO 055 TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS F/6 17/1 SONAR TEST AND TEST INSTRUMENTATION SUPPORT (U) MAR 79 0 D BAKER N00140-76-C-64a7... SONAR TEST AND TEST INSTRUMENTATION SUPPORT quarterly progress report September - 30 November 197Pj 6. PERFORMING ORG. REPORT NUMBER 7. AUTHOR(e) S...involves technical support with sonar testing, test instrumentation, and documentation. This report describes progress made under the tasks that are

Evaluation of platelet adhesion and activation on polymers: Round-robin study to assess inter-center variability.

PubMed

Braune, S; Sperling, C; Maitz, M F; Steinseifer, U; Clauser, J; Hiebl, B; Krajewski, S; Wendel, H P; Jung, F

2017-10-01

The regulatory agencies provide recommendations rather than protocols or standard operation procedures for the hemocompatibility evaluation of novel materials e.g. for cardiovascular applications. Thus, there is a lack of specifications with regard to test setups and procedures. As a consequence, laboratories worldwide perform in vitro assays under substantially different test conditions, so that inter-laboratory and inter-study comparisons are impossible. Here, we report about a prospective, randomized and double-blind multicenter trial which demonstrates that standardization of in vitro test protocols allows a reproducible assessment of platelet adhesion and activation from fresh human platelet rich plasma as possible indicators of the thrombogenicity of cardiovascular implants. Standardization of the reported static in vitro setup resulted in a laboratory independent scoring of the following materials: poly(dimethyl siloxane) (PDMS), poly(ethylene terephthalate) (PET) and poly(tetrafluoro ethylene) (PTFE). The results of this in vitro study provide evidence that inter-laboratory and inter-study comparisons can be achieved for the evaluation of the adhesion and activation of platelets on blood-contacting biomaterials by stringent standardization of test protocols. Copyright © 2017 Elsevier B.V. All rights reserved.

Genome-wide DNA methylation map of human neutrophils reveals widespread inter-individual epigenetic variation

PubMed Central

Chatterjee, Aniruddha; Stockwell, Peter A.; Rodger, Euan J.; Duncan, Elizabeth J.; Parry, Matthew F.; Weeks, Robert J.; Morison, Ian M.

2015-01-01

The extent of variation in DNA methylation patterns in healthy individuals is not yet well documented. Identification of inter-individual epigenetic variation is important for understanding phenotypic variation and disease susceptibility. Using neutrophils from a cohort of healthy individuals, we generated base-resolution DNA methylation maps to document inter-individual epigenetic variation. We identified 12851 autosomal inter-individual variably methylated fragments (iVMFs). Gene promoters were the least variable, whereas gene body and upstream regions showed higher variation in DNA methylation. The iVMFs were relatively enriched in repetitive elements compared to non-iVMFs, and were associated with genome regulation and chromatin function elements. Further, variably methylated genes were disproportionately associated with regulation of transcription, responsive function and signal transduction pathways. Transcriptome analysis indicates that iVMF methylation at differentially expressed exons has a positive correlation and local effect on the inclusion of that exon in the mRNA transcript. PMID:26612583

Inter-laboratory agreement on embryo classification and clinical decision: Conventional morphological assessment vs. time lapse.

PubMed

Martínez-Granados, Luis; Serrano, María; González-Utor, Antonio; Ortíz, Nereyda; Badajoz, Vicente; Olaya, Enrique; Prados, Nicolás; Boada, Montse; Castilla, Jose A

2017-01-01

The aim of this study is to determine inter-laboratory variability on embryo assessment using time-lapse platform and conventional morphological assessment. This study compares the data obtained from a pilot study of external quality control (EQC) of time lapse, performed in 2014, with the classical EQC of the Spanish Society for the Study of Reproductive Biology (ASEBIR) performed in 2013 and 2014. In total, 24 laboratories (8 using EmbryoScope™, 15 using Primo Vision™ and one with both platforms) took part in the pilot study. The clinics that used EmbryoScope™ analysed 31 embryos and those using Primo Vision™ analysed 35. The classical EQC was implemented by 39 clinics, based on an analysis of 25 embryos per year. Both groups were required to evaluate various qualitative morphological variables (cell fragmentation, the presence of vacuoles, blastomere asymmetry and multinucleation), to classify the embryos in accordance with ASEBIR criteria and to stipulate the clinical decision taken. In the EQC time-lapse pilot study, the groups were asked to determine, as well as the above characteristics, the embryo development times, the number, opposition and size of pronuclei, the direct division of 1 into 3 cells and/or of 3 into 5 cells and false divisions. The degree of agreement was determined by calculating the intra-class correlation coefficients and the coefficient of variation for the quantitative variables and the Gwet index for the qualitative variables. For both EmbryoScope™ and Primo Vision™, two periods of greater inter-laboratory variability were observed in the times of embryo development events. One peak of variability was recorded among the laboratories addressing the first embryo events (extrusion of the second polar body and the appearance of pronuclei); the second peak took place between the times corresponding to the 8-cell and morula stages. In most of the qualitative variables analysed regarding embryo development, there was almost

Inter-laboratory agreement on embryo classification and clinical decision: Conventional morphological assessment vs. time lapse

PubMed Central

Serrano, María; González-Utor, Antonio; Ortíz, Nereyda; Badajoz, Vicente; Olaya, Enrique; Prados, Nicolás; Boada, Montse; Castilla, Jose A.

2017-01-01

The aim of this study is to determine inter-laboratory variability on embryo assessment using time-lapse platform and conventional morphological assessment. This study compares the data obtained from a pilot study of external quality control (EQC) of time lapse, performed in 2014, with the classical EQC of the Spanish Society for the Study of Reproductive Biology (ASEBIR) performed in 2013 and 2014. In total, 24 laboratories (8 using EmbryoScope™, 15 using Primo Vision™ and one with both platforms) took part in the pilot study. The clinics that used EmbryoScope™ analysed 31 embryos and those using Primo Vision™ analysed 35. The classical EQC was implemented by 39 clinics, based on an analysis of 25 embryos per year. Both groups were required to evaluate various qualitative morphological variables (cell fragmentation, the presence of vacuoles, blastomere asymmetry and multinucleation), to classify the embryos in accordance with ASEBIR criteria and to stipulate the clinical decision taken. In the EQC time-lapse pilot study, the groups were asked to determine, as well as the above characteristics, the embryo development times, the number, opposition and size of pronuclei, the direct division of 1 into 3 cells and/or of 3 into 5 cells and false divisions. The degree of agreement was determined by calculating the intra-class correlation coefficients and the coefficient of variation for the quantitative variables and the Gwet index for the qualitative variables. For both EmbryoScope™ and Primo Vision™, two periods of greater inter-laboratory variability were observed in the times of embryo development events. One peak of variability was recorded among the laboratories addressing the first embryo events (extrusion of the second polar body and the appearance of pronuclei); the second peak took place between the times corresponding to the 8-cell and morula stages. In most of the qualitative variables analysed regarding embryo development, there was almost

Critical evaluation of connectivity-based point of care testing systems of glucose in a hospital environment.

PubMed

Floré, Katelijne M J; Fiers, Tom; Delanghe, Joris R

2008-01-01

In recent years a number of point of care testing (POCT) glucometers were introduced on the market. We investigated the analytical variability (lot-to-lot variation, calibration error, inter-instrument and inter-operator variability) of glucose POCT systems in a university hospital environment and compared these results with the analytical needs required for tight glucose monitoring. The reference hexokinase method was compared to different POCT systems based on glucose oxidase (blood gas instruments) or glucose dehydrogenase (handheld glucometers). Based upon daily internal quality control data, total errors were calculated for the various glucose methods and the analytical variability of the glucometers was estimated. The total error of the glucometers exceeded by far the desirable analytical specifications (based on a biological variability model). Lot-to-lot variation, inter-instrument variation and inter-operator variability contributed approximately equally to total variance. As in a hospital environment, distribution of hematocrit values is broad, converting blood glucose into plasma values using a fixed factor further increases variance. The percentage of outliers exceeded the ISO 15197 criteria in a broad glucose concentration range. Total analytical variation of handheld glucometers is larger than expected. Clinicians should be aware that the variability of glucose measurements obtained by blood gas instruments is lower than results obtained with handheld glucometers on capillary blood.

North Atlantic simulations in Coordinated Ocean-ice Reference Experiments phase II (CORE-II). Part II: Inter-annual to decadal variability

NASA Astrophysics Data System (ADS)

Danabasoglu, Gokhan; Yeager, Steve G.; Kim, Who M.; Behrens, Erik; Bentsen, Mats; Bi, Daohua; Biastoch, Arne; Bleck, Rainer; Böning, Claus; Bozec, Alexandra; Canuto, Vittorio M.; Cassou, Christophe; Chassignet, Eric; Coward, Andrew C.; Danilov, Sergey; Diansky, Nikolay; Drange, Helge; Farneti, Riccardo; Fernandez, Elodie; Fogli, Pier Giuseppe; Forget, Gael; Fujii, Yosuke; Griffies, Stephen M.; Gusev, Anatoly; Heimbach, Patrick; Howard, Armando; Ilicak, Mehmet; Jung, Thomas; Karspeck, Alicia R.; Kelley, Maxwell; Large, William G.; Leboissetier, Anthony; Lu, Jianhua; Madec, Gurvan; Marsland, Simon J.; Masina, Simona; Navarra, Antonio; Nurser, A. J. George; Pirani, Anna; Romanou, Anastasia; Salas y Mélia, David; Samuels, Bonita L.; Scheinert, Markus; Sidorenko, Dmitry; Sun, Shan; Treguier, Anne-Marie; Tsujino, Hiroyuki; Uotila, Petteri; Valcke, Sophie; Voldoire, Aurore; Wang, Qiang; Yashayaev, Igor

2016-01-01

Simulated inter-annual to decadal variability and trends in the North Atlantic for the 1958-2007 period from twenty global ocean - sea-ice coupled models are presented. These simulations are performed as contributions to the second phase of the Coordinated Ocean-ice Reference Experiments (CORE-II). The study is Part II of our companion paper (Danabasoglu et al., 2014) which documented the mean states in the North Atlantic from the same models. A major focus of the present study is the representation of Atlantic meridional overturning circulation (AMOC) variability in the participating models. Relationships between AMOC variability and those of some other related variables, such as subpolar mixed layer depths, the North Atlantic Oscillation (NAO), and the Labrador Sea upper-ocean hydrographic properties, are also investigated. In general, AMOC variability shows three distinct stages. During the first stage that lasts until the mid- to late-1970s, AMOC is relatively steady, remaining lower than its long-term (1958-2007) mean. Thereafter, AMOC intensifies with maximum transports achieved in the mid- to late-1990s. This enhancement is then followed by a weakening trend until the end of our integration period. This sequence of low frequency AMOC variability is consistent with previous studies. Regarding strengthening of AMOC between about the mid-1970s and the mid-1990s, our results support a previously identified variability mechanism where AMOC intensification is connected to increased deep water formation in the subpolar North Atlantic, driven by NAO-related surface fluxes. The simulations tend to show general agreement in their temporal representations of, for example, AMOC, sea surface temperature (SST), and subpolar mixed layer depth variabilities. In particular, the observed variability of the North Atlantic SSTs is captured well by all models. These findings indicate that simulated variability and trends are primarily dictated by the atmospheric datasets which

North Atlantic Simulations in Coordinated Ocean-Ice Reference Experiments Phase II (CORE-II) . Part II; Inter-Annual to Decadal Variability

NASA Technical Reports Server (NTRS)

Danabasoglu, Gokhan; Yeager, Steve G.; Kim, Who M.; Behrens, Erik; Bentsen, Mats; Bi, Daohua; Biastoch, Arne; Bleck, Rainer; Boening, Claus; Bozec, Alexandra;

Artwork as Technics

ERIC Educational Resources Information Center

Jackson, Mark

2016-01-01

"Artwork as technics" opens discussion on activating aesthetics in educational contexts by arguing that we require some fundamental revision in understanding relations between aesthetics and technology in contexts where education is primarily encountered instrumentally and technologically. The paper addresses this through the writing of…

26 CFR 1.1275-5 - Variable rate debt instruments.

Code of Federal Regulations, 2010 CFR

2010-04-01

... nonpublicly traded property. A debt instrument (other than a tax-exempt obligation) that would otherwise... variations in the cost of newly borrowed funds in the currency in which the debt instrument is denominated... on the yield of actively traded personal property (within the meaning of section 1092(d)(1)). (ii...

[A survey instrument for evaluating psychological variables and risky sexual behavior among young adults at two university centers in Mexico].

PubMed

Piña López, Julio A; Robles Montijo, Susana; Rivera Icedo, Blanca M

2007-11-01

To measure the psychometric attributes of a survey instrument designed to evaluate historical and context variables that lead to high-risk sexual behaviors among a sample of university students in Mexico. Cross-sectional study of a sample of 1 346 university students in Mexico: 784 from the Sonora State Center for Higher Education in Hermosillo, Sonora, or 33.2% of its total enrollment; and 562 from the National Autonomous University of Mexico, at Tlalnepantla campus in Mexico State, or 23.5% of its total enrollment. The study took place in Hermosillo during the month of October 2006 and in Tlalnepantla from January to March 2006. The survey had 11 questions on sociodemographics, 7 on risky sexual behaviors, 22 on related motives, 8 on social context, and 6 on physical status prior to sexual relations. The survey was evaluated in terms of how well the questions were understood, its conceptual validity, and reliability. The final version of the survey instrument was composed of 44 questions. The reliability analysis produced an overall Cronbach alpha value of 0.821, taking into account all the variables combined and grouped by factor. Three factors were found that together accounted for 38.36% of the total variance: reasons for not using a condom in the first sexual relationship or throughout life, reasons for inconsistent use of a condom with a casual sex partner, and willingness to become sexually active and to engage in casual sex. The psychometric attributes of this survey instrument were found to be satisfactory. Those interested in using this instrument should become familiar with the theoretical model on which it is based, since understanding the results depends on properly defining the historical and context variables, and their interaction.

Inter-annual rainfall variability in the eastern Antilles and coupling with the regional and intra-seasonal circulation

NASA Astrophysics Data System (ADS)

Jury, Mark R.

2016-11-01

Climate variability in the eastern Antilles island chain is analyzed via principal component analysis of high-resolution monthly rainfall in the period 1981-2013. The second mode reflecting higher rainfall in July-October season between Martinique and Grenada is the focus of this study. Higher rainfall corresponds with a weakened trade wind and boundary current along the southern edge of the Caribbean. This quells the coastal upwelling off Venezuela and builds the freshwater plume east of Trinidad. There is corresponding upper easterly wind flow that intensifies passing tropical waves. During a storm event over the Antilles on 4-5 October 2010, there was inflow from east of Guyana where low salinity and high sea temperatures enable surplus latent heat fluxes. A N-S convective rain band forms ˜500 km east of the cyclonic vortex. Many features at the weather timescale reflect the seasonal correlation and composite difference maps and El Nino Southern Oscillation (ENSO) modulation of oceanic inter-basin transfers.

Technical Performance as a Predictor of Clinical Outcomes in Laparoscopic Gastric Cancer Surgery.

PubMed

Fecso, Andras B; Bhatti, Junaid A; Stotland, Peter K; Quereshy, Fayez A; Grantcharov, Teodor P

2018-03-23

The purpose of this study was to evaluate the relationship between technical performance and patient outcomes in laparoscopic gastric cancer surgery. Laparoscopic gastrectomy for cancer is an advanced procedure with high rate of postoperative morbidity and mortality. Many variables including patient, disease, and perioperative management factors have been shown to impact postoperative outcomes; however, the role of surgical performance is insufficiently investigated. A retrospective review was performed for all patients who had undergone laparoscopic gastrectomy for cancer at 3 teaching institutions between 2009 and 2015. Patients with available, unedited video-recording of their procedure were included in the study. Video files were rated for technical performance, using Objective Structured Assessments of Technical Skills (OSATS) and Generic Error Rating Tool instruments. The main outcome variable was major short-term complications. The effect of technical performance on patient outcomes was assessed using logistic regression analysis with backward selection strategy. Sixty-one patients with available video recordings were included in the study. The overall complication rate was 29.5%. The mean Charlson comorbidity index, type of procedure, and the global OSATS score were included in the final predictive model. Lower performance score (OSATS ≤29) remained an independent predictor for major short-term outcomes (odds ratio 6.49), while adjusting for comorbidities and type of procedure. Intraoperative technical performance predicts major short-term outcomes in laparoscopic gastrectomy for cancer. Ongoing assessment and enhancement of surgical skills using modern, evidence-based strategies might improve short-term patient outcomes. Future work should focus on developing and studying the effectiveness of such interventions in laparoscopic gastric cancer surgery.

[Benchmarking using different measurement instruments and the management of measurement variability].

PubMed

Blankers, M; Barendregt, M; Dekker, J J M

2016-01-01

In mental health care centres in the Netherlands outcome data are collected using a variety of outcome instruments. This may have implications for the comparability of outcome results between different centres. To discuss recent findings regarding the extent to which the eight instruments currently used in clinical practice report comparable results. Our study is based on a combination of literature review and empirical research. The results obtained with the eight instruments are not equivalent. Patients symptom reductions appear larger with some instruments than with others. The current practice of benchmarking in the Dutch mental health system would have greater validity if the number of different instruments would be reduced. State-of-the-art calibration studies are necessary to validate the comparability of the remaining instruments. Ideally, all mental health centres will soon use one instrument per care domain to measure treatment outcome.

Biomechanical risk factors for proximal junctional kyphosis: a detailed numerical analysis of surgical instrumentation variables.

PubMed

Cammarata, Marco; Aubin, Carl-Éric; Wang, Xiaoyu; Mac-Thiong, Jean-Marc

2014-04-15

Biomechanical analysis of proximal junctional kyphosis (PJK) through computer simulations and sensitivity analysis. To gain biomechanical knowledge on the risk of PJK and find surgical solutions to reduce the risks. PJK is a pathological kyphotic deformity adjacent to the instrumentation. Clinical studies have documented its risk factors, but still little is known on how it is correlated with various individual instrumentation variables. Biomechanical spine models of 6 patients with adult scoliosis were developed, validated, and then used to perform 576 simulations, varying the proximal dissection procedure, the implant type at the upper instrumented vertebra, the sagittal rod curvature, and the proximal diameter of the proximal transition rods. Four biomechanical indices--the proximal junctional kyphotic angle, thoracic kyphosis, proximal flexion force, and proximal flexion moment--were assessed. The bilateral complete facetectomy, the posterior ligaments resection, and the combination of both increased the proximal junctional kyphotic angle (respectively, by 10%, 28% and 53%) and the proximal flexion force (4%, 12%, and 22%) and moment (16%, 44%, and 83%). Compared with pedicle screws at upper instrumented vertebra, proximal transverse process hooks reduced the 3 biomechanical indices by approximately 26%. The use of proximal transition rods with reduced proximal diameter from 5.5 mm to 4 mm decreased the proximal junctional kyphotic angle (by 6%) and the proximal flexion force (4%) and moment (8%). The increase of the sagittal rod curvature from 10° to 20°, 30°, and 40° increased the proximal junctional kyphotic angle (by 6%, 13%, and 19%) and the proximal flexion force (3%, 7%, and 10%) and moment (9%, 18%, and 27%). Preserving more posterior proximal intervertebral elements, the use of transition rods and transverse process hooks at upper instrumented vertebra, and reducing the global sagittal rod curvature each decreased the 4 biomechanical indices that

On Aethalometer measurement uncertainties and an instrument correction factor for the Arctic

NASA Astrophysics Data System (ADS)

Backman, John; Schmeisser, Lauren; Virkkula, Aki; Ogren, John A.; Asmi, Eija; Starkweather, Sandra; Sharma, Sangeeta; Eleftheriadis, Konstantinos; Uttal, Taneil; Jefferson, Anne; Bergin, Michael; Makshtas, Alexander; Tunved, Peter; Fiebig, Markus

2017-12-01

Several types of filter-based instruments are used to estimate aerosol light absorption coefficients. Two significant results are presented based on Aethalometer measurements at six Arctic stations from 2012 to 2014. First, an alternative method of post-processing the Aethalometer data is presented, which reduces measurement noise and lowers the detection limit of the instrument more effectively than boxcar averaging. The biggest benefit of this approach can be achieved if instrument drift is minimised. Moreover, by using an attenuation threshold criterion for data post-processing, the relative uncertainty from the electronic noise of the instrument is kept constant. This approach results in a time series with a variable collection time (Δt) but with a constant relative uncertainty with regard to electronic noise in the instrument. An additional advantage of this method is that the detection limit of the instrument will be lowered at small aerosol concentrations at the expense of temporal resolution, whereas there is little to no loss in temporal resolution at high aerosol concentrations ( > 2.1-6.7 Mm-1 as measured by the Aethalometers). At high aerosol concentrations, minimising the detection limit of the instrument is less critical. Additionally, utilising co-located filter-based absorption photometers, a correction factor is presented for the Arctic that can be used in Aethalometer corrections available in literature. The correction factor of 3.45 was calculated for low-elevation Arctic stations. This correction factor harmonises Aethalometer attenuation coefficients with light absorption coefficients as measured by the co-located light absorption photometers. Using one correction factor for Arctic Aethalometers has the advantage that measurements between stations become more inter-comparable.

Variability in bimanual wheelchair propulsion: consistency of two instrumented wheels during handrim wheelchair propulsion on a motor driven treadmill

PubMed Central

2013-01-01

Background Handrim wheelchair propulsion is a complex bimanual motor task. The bimanually applied forces on the rims determine the speed and direction of locomotion. Measurements of forces and torques on the handrim are important to study status and change of propulsion technique (and consequently mechanical strain) due to processes of learning, training or the wheelchair configuration. The purpose of this study was to compare the simultaneous outcomes of two different measurement-wheels attached to the different sides of the wheelchair, to determine measurement consistency within and between these wheels given the expected inter- and intra-limb variability as a consequence of motor control. Methods Nine able-bodied subjects received a three-week low-intensity handrim wheelchair practice intervention. They then performed three four-minute trials of wheelchair propulsion in an instrumented hand rim wheelchair on a motor-driven treadmill at a fixed belt speed. The two measurement-wheels on each side of the wheelchair measured forces and torques of one of the two upper limbs, which simultaneously perform the push action over time. The resulting data were compared as direct output using cross-correlation on the torque around the wheel-axle. Calculated push characteristics such as power production and speed were compared using an intra-class correlation. Results Measured torque around the wheel axle of the two measurement-wheels had a high average cross-correlation of 0.98 (std=0.01). Unilateral mean power output over a minute was found to have an intra-class correlation of 0.89 between the wheels. Although the difference over the pushes between left and right power output had a high variability, the mean difference between the measurement-wheels was low at 0.03 W (std=1.60). Other push characteristics showed even higher ICC’s (>0.9). Conclusions A good agreement between both measurement-wheels was found at the level of the power output. This indicates a high

Breastfeeding and the risk of childhood asthma: A two-stage instrumental variable analysis to address endogeneity.

PubMed

Sharma, Nivita D

2017-09-01

Several explanations for the inconsistent results on the effects of breastfeeding on childhood asthma have been suggested. The purpose of this study was to investigate one unexplored explanation, which is the presence of a potential endogenous relationship between breastfeeding and childhood asthma. Endogeneity exists when an explanatory variable is correlated with the error term for reasons such as selection bias, reverse causality, and unmeasured confounders. Unadjusted endogeneity will bias the effect of breastfeeding on childhood asthma. To investigate potential endogeneity, a cross-sectional study of breastfeeding practices and incidence of childhood asthma in 87 pediatric patients in Georgia, the USA, was conducted using generalized linear modeling and a two-stage instrumental variable analysis. First, the relationship between breastfeeding and childhood asthma was analyzed without considering endogeneity. Second, tests for presence of endogeneity were performed and having detected endogeneity between breastfeeding and childhood asthma, a two-stage instrumental variable analysis was performed. The first stage of this analysis estimated the duration of breastfeeding and the second-stage estimated the risk of childhood asthma. When endogeneity was not taken into account, duration of breastfeeding was found to significantly increase the risk of childhood asthma (relative risk ratio [RR]=2.020, 95% confidence interval [CI]: [1.143-3.570]). After adjusting for endogeneity, duration of breastfeeding significantly reduced the risk of childhood asthma (RR=0.003, 95% CI: [0.000-0.240]). The findings suggest that researchers should consider evaluating how the presence of endogeneity could affect the relationship between duration of breastfeeding and the risk of childhood asthma. © 2017 EAACI and John Wiley and Sons A/S. Published by John Wiley and Sons Ltd.

A recent U.S. patent process for a musical instrument

NASA Astrophysics Data System (ADS)

Baecker, James I.

2005-09-01

The ins and outs of going from a novel musical instrument concept to issuance of a U.S. patent. The technical work performed included the development of a musical instrument based on space-frame body construction and a definition of the instrument body's resonance characteristics. The result required a description of the invention and communication with the patent attorney and conveying a correct perception of the invention to the U.S. Patent Office. This presentation describes several technical, practical, legal, and commercial issues encountered during the patent process by the inventors and their business entity. On 7 September 2004, U.S. Patent No. 6,787,688 for a musical instrument was issued and assigned by the inventors to Harmos Music, Ltd.

On inter-hemispheric coupling in the middle atmosphere

NASA Astrophysics Data System (ADS)

Karlsson, Bodil; Bailey, S.; Benze, S.; Gumbel, J.; Harvey, V. L.; Kürnich, H.; Lossow, S.; McLandress, D. Marsh, C.; Merkel, A. W.; Mills, M.; Randall, C. E.; Russell, J.; Shepherd, T. G.

On inter-hemispheric coupling in the middle atmosphere From recent studies it is evident that planetary wave activity in the winter hemisphere influences the high-latitude summer mesosphere on the opposite side of the globe. This is an extraordinary example of multi-scale wave-mean flow interaction. The first indication of this inter-hemispheric coupling came from a model study by Becker and Schmitz (2003). Since then, the results have been reproduced in several models, and observations have confirmed the existence of this link. We present current understanding of inter-hemispheric coupling and its consequences for the middle atmosphere, focusing on the summer mesosphere where polar mesospheric clouds (PMCs) form. The results shown are based on year-to-year and intra-seasonal variability in PMCs ob-served by the Odin satellite and the Aeronomy of Ice in the Mesosphere (AIM) satellite, as well as on model results from the extended Canadian Middle Atmosphere Model (CMAM), the Whole Atmosphere Community Climate Model (WACCM) and the Kühlungsborn Mechanis-u tic general Circulation Model (KMCM). The latter has been used to pinpoint the proposed mechanism behind the inter-hemispheric coupling.

Root-associated fungi of Vaccinium carlesii in subtropical forests of China: intra- and inter-annual variability and impacts of human disturbances

PubMed Central

Zhang, Yanhua; Ni, Jian; Tang, Fangping; Pei, Kequan; Luo, Yiqi; Jiang, Lifen; Sun, Lifu; Liang, Yu

2016-01-01

Ericoid mycorrhiza (ERM) are expected to facilitate establishment of ericaceous plants in harsh habitats. However, diversity and driving factors of the root-associated fungi of ericaceous plants are poorly understood. In this study, hair-root samples of Vaccinium carlesii were taken from four forest types: old growth forests (OGF), secondary forests with once or twice cutting (SEC I and SEC II), and Cunninghamia lanceolata plantation (PLF). Fungal communities were determined using high-throughput sequencing, and impacts of human disturbances and the intra- and inter-annual variability of root-associated fungal community were evaluated. Diverse fungal taxa were observed and our results showed that (1) Intra- and inter-annual changes in root-associated fungal community were found, and the Basidiomycota to Ascomycota ratio was related to mean temperature of the sampling month; (2) Human disturbances significantly affected structure of root-associated fungal community of V. carlesii, and two secondary forest types were similar in root-associated fungal community and were closer to that of the old growth forest; (3) Plant community composition, edaphic parameters, and geographic factors significantly affected root-associated fungal communities of V. carlesii. These results may be helpful in better understanding the maintenance mechanisms of fungal diversity associated with hair roots of ERM plants under human disturbances. PMID:26928608

Preliminary results of a prospective study of inter- and intra-user variability of the Royal Veterinary College corneal clarity score (RVC-CCS) for use in veterinary practice.

PubMed

Sanchez, Rick F; Dawson, Charlotte; Matas Riera, Màrian; Escanilla, Natàlia

2016-07-01

To introduce a new corneal clarity score for use in small animals and describe its inter- and intra-user variability. Twelve dogs and two cats with corneal abnormalities and five dogs with healthy corneas. Four examiners scored every patient twice and never consecutively, focusing on the central cornea. The peripheral cornea was scored separately. The following scoring system was used to describe corneal clarity: G0: no fundus reflection is visible on retroillumination (RI) using a head-mounted indirect ophthalmoscope. G1: a fundus reflection is visible with RI. G2: a 0.1-mm diameter light beam is visible on the anterior surface of the iris and/or lens. G3: gross fundic features are visible when viewed with indirect ophthalmoscopy (IO) using a head-mounted indirect ophthalmoscope and a hand-held 30D lens, although fine details are not clear. G4: fine details of the fundic features are clearly visible with IO. The minimum grades given were analyzed for inter- and intra-user variability with kappa analysis. Intra- and interuser variability of the central corneal clarity ranged from 0.78 to 0.96, showing substantial to almost perfect reproducibility, and from 0.66 to 0.91, showing substantial to almost perfect reliability, respectively. Intra- and interuser variability of the peripheral cornea ranged from 0.83 to 0.95, showing almost perfect agreement, and from 0.53 to 0.91, showing moderate to almost perfect agreement. The RVC-CCS is well suited to assess and monitor central corneal clarity in small animals and to compare outcomes between studies and different surgeons. © 2015 American College of Veterinary Ophthalmologists.

Effect of Highly Active Antiretroviral Therapy on Incident AIDS Using Calendar Period as an Instrumental Variable

PubMed Central

Cole, Stephen R.; Greenland, Sander; Brown, Todd T.; Chmiel, Joan S.; Kingsley, Lawrence; Detels, Roger

2009-01-01

Human immunodeficiency virus (HIV) researchers often use calendar periods as an imperfect proxy for highly active antiretroviral therapy (HAART) when estimating the effect of HAART on HIV disease progression. The authors report on 614 HIV-positive homosexual men followed from 1984 to 2007 in 4 US cities. During 5,321 person-years, 268 of 614 men incurred acquired immunodeficiency syndrome, 49 died, and 90 were lost to follow-up. Comparing the pre-HAART calendar period (<1996) with the HAART calendar period (≥1996) resulted in a naive rate ratio of 3.62 (95% confidence limits: 2.67, 4.92). However, this estimate is likely biased because of misclassification of HAART use by calendar period. Simple calendar period approaches may circumvent confounding by indication at the cost of inducing exposure misclassification. To correct this misclassification, the authors propose an instrumental-variable estimator analogous to ones previously used for noncompliance corrections in randomized clinical trials. When the pre-HAART calendar period was compared with the HAART calendar period, the instrumental-variable rate ratio was 5.02 (95% confidence limits: 3.45, 7.31), 39% higher than the naive result. Weighting by the inverse probability of calendar period given age at seroconversion, race/ethnicity, and time since seroconversion did not appreciably alter the results. These methods may help resolve discrepancies between observational and randomized evidence. PMID:19318615

Evaluation of Inter-Mountain Labs infrasound sensors : July 2007.

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

Hart, Darren M.

2007-10-01

Sandia National Laboratories has tested and evaluated three Inter Mountain Labs infrasound sensors. The test results included in this report were in response to static and tonal-dynamic input signals. Most test methodologies used were based on IEEE Standards 1057 for Digitizing Waveform Recorders and 1241 for Analog to Digital Converters; others were designed by Sandia specifically for infrasound application evaluation and for supplementary criteria not addressed in the IEEE standards. The objective of this work was to evaluate the overall technical performance of the Inter Mountain Labs (IML) infrasound sensor model SS. The results of this evaluation were only comparedmore » to relevant noise models; due to a lack of manufactures documentation notes on the sensors under test prior to testing. The tests selected for this system were chosen to demonstrate different performance aspects of the components under test.« less

Effect of corruption on healthcare satisfaction in post-soviet nations: A cross-country instrumental variable analysis of twelve countries.

PubMed

Habibov, Nazim

2016-03-01

There is the lack of consensus about the effect of corruption on healthcare satisfaction in transitional countries. Interpreting the burgeoning literature on this topic has proven difficult due to reverse causality and omitted variable bias. In this study, the effect of corruption on healthcare satisfaction is investigated in a set of 12 Post-Socialist countries using instrumental variable regression on the sample of 2010 Life in Transition survey (N = 8655). The results indicate that experiencing corruption significantly reduces healthcare satisfaction. Copyright © 2016 The Author. Published by Elsevier Ltd.. All rights reserved.

First-Passage-Time Distribution for Variable-Diffusion Processes

NASA Astrophysics Data System (ADS)

Barney, Liberty; Gunaratne, Gemunu H.

2017-05-01

First-passage-time distribution, which presents the likelihood of a stock reaching a pre-specified price at a given time, is useful in establishing the value of financial instruments and in designing trading strategies. First-passage-time distribution for Wiener processes has a single peak, while that for stocks exhibits a notable second peak within a trading day. This feature has only been discussed sporadically—often dismissed as due to insufficient/incorrect data or circumvented by conversion to tick time—and to the best of our knowledge has not been explained in terms of the underlying stochastic process. It was shown previously that intra-day variations in the market can be modeled by a stochastic process containing two variable-diffusion processes (Hua et al. in, Physica A 419:221-233, 2015). We show here that the first-passage-time distribution of this two-stage variable-diffusion model does exhibit a behavior similar to the empirical observation. In addition, we find that an extended model incorporating overnight price fluctuations exhibits intra- and inter-day behavior similar to those of empirical first-passage-time distributions.

Developing an instrument to measure heart failure disease management program intensity and complexity.

PubMed

Riegel, Barbara; Lee, Christopher S; Sochalski, Julie

2010-05-01

Comparing disease management programs and their effects is difficult because of wide variability in program intensity and complexity. The purpose of this effort was to develop an instrument that can be used to describe the intensity and complexity of heart failure (HF) disease management programs. Specific composition criteria were taken from the American Heart Association (AHA) taxonomy of disease management and hierarchically scored to allow users to describe the intensity and complexity of the domains and subdomains of HF disease management programs. The HF Disease Management Scoring Instrument (HF-DMSI) incorporates 6 of the 8 domains from the taxonomy: recipient, intervention content, delivery personnel, method of communication, intensity/complexity, and environment. The 3 intervention content subdomains (education/counseling, medication management, and peer support) are described separately. In this first test of the HF-DMSI, overall intensity (measured as duration) and complexity were rated using an ordinal scoring system. Possible scores reflect a clinical rationale and differ by category, with zero given only if the element could potentially be missing (eg, surveillance by remote monitoring). Content validity was evident as the instrument matches the existing AHA taxonomy. After revision and refinement, 2 authors obtained an inter-rater reliability intraclass correlation coefficient score of 0.918 (confidence interval, 0.880 to 0.944, P<0.001) in their rating of 12 studies. The areas with most variability among programs were delivery personnel and method of communication. The HF-DMSI is useful for describing the intensity and complexity of HF disease management programs.

Treatment Effect Estimation Using Nonlinear Two-Stage Instrumental Variable Estimators: Another Cautionary Note.

PubMed

Chapman, Cole G; Brooks, John M

2016-12-01

To examine the settings of simulation evidence supporting use of nonlinear two-stage residual inclusion (2SRI) instrumental variable (IV) methods for estimating average treatment effects (ATE) using observational data and investigate potential bias of 2SRI across alternative scenarios of essential heterogeneity and uniqueness of marginal patients. Potential bias of linear and nonlinear IV methods for ATE and local average treatment effects (LATE) is assessed using simulation models with a binary outcome and binary endogenous treatment across settings varying by the relationship between treatment effectiveness and treatment choice. Results show that nonlinear 2SRI models produce estimates of ATE and LATE that are substantially biased when the relationships between treatment and outcome for marginal patients are unique from relationships for the full population. Bias of linear IV estimates for LATE was low across all scenarios. Researchers are increasingly opting for nonlinear 2SRI to estimate treatment effects in models with binary and otherwise inherently nonlinear dependent variables, believing that it produces generally unbiased and consistent estimates. This research shows that positive properties of nonlinear 2SRI rely on assumptions about the relationships between treatment effect heterogeneity and choice. © Health Research and Educational Trust.

Development and testing of an assessment instrument for the formative peer review of significant event analyses.

PubMed

McKay, J; Murphy, D J; Bowie, P; Schmuck, M-L; Lough, M; Eva, K W

2007-04-01

To establish the content validity and specific aspects of reliability for an assessment instrument designed to provide formative feedback to general practitioners (GPs) on the quality of their written analysis of a significant event. Content validity was quantified by application of a content validity index. Reliability testing involved a nested design, with 5 cells, each containing 4 assessors, rating 20 unique significant event analysis (SEA) reports (10 each from experienced GPs and GPs in training) using the assessment instrument. The variance attributable to each identified variable in the study was established by analysis of variance. Generalisability theory was then used to investigate the instrument's ability to discriminate among SEA reports. Content validity was demonstrated with at least 8 of 10 experts endorsing all 10 items of the assessment instrument. The overall G coefficient for the instrument was moderate to good (G>0.70), indicating that the instrument can provide consistent information on the standard achieved by the SEA report. There was moderate inter-rater reliability (G>0.60) when four raters were used to judge the quality of the SEA. This study provides the first steps towards validating an instrument that can provide educational feedback to GPs on their analysis of significant events. The key area identified to improve instrument reliability is variation among peer assessors in their assessment of SEA reports. Further validity and reliability testing should be carried out to provide GPs, their appraisers and contractual bodies with a validated feedback instrument on this aspect of the general practice quality agenda.

Kelvin wave coupling from TIMED and GOCE: Inter/intra-annual variability and solar activity effects

NASA Astrophysics Data System (ADS)

Gasperini, Federico; Forbes, Jeffrey M.; Doornbos, Eelco N.; Bruinsma, Sean L.

2018-06-01

The primary mechanism through which energy and momentum are transferred from the lower atmosphere to the thermosphere is through the generation and propagation of atmospheric waves. It is becoming increasingly evident that a few waves from the tropical wave spectrum preferentially propagate into the thermosphere and contribute to modify satellite drag. Two of the more prominent and well-established tropical waves are Kelvin waves: the eastward-propagating 3-day ultra-fast Kelvin wave (UFKW) and the eastward-propagating diurnal tide with zonal wave number 3 (DE3). In this work, Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) temperatures at 110 km and Gravity field and steady-state Ocean Circulation Explorer (GOCE) neutral densities and cross-track winds near 260 km are used to demonstrate vertical coupling in this height regime due to the UFKW and DE3. Significant inter- and intra-annual variability is found in DE3 and the UFKW, with evidence of latitudinal broadening and filtering of the latitude structures with height due to the effect of dissipation and mean winds. Additionally, anti-correlation between the vertical penetration of these waves to the middle thermosphere and solar activity level is established and explained through the effect of molecular dissipation.

Instrumentation for Aerosol and Gas Speciation

NASA Technical Reports Server (NTRS)

Coggiola, Michael J.

1998-01-01

Using support from NASA Grant No. NAG 2-963, SRI International successfully completed the project, entitled, 'Instrumentation for Aerosol and Gas Speciation.' This effort (SRI Project 7383) covered the design, fabrication, testing, and deployment of a real-time aerosol speciation instrument in NASA's DC-8 aircraft during the Spring 1996 SUbsonic aircraft: Contrail and Cloud Effects Special Study (SUCCESS) mission. This final technical report describes the pertinent details of the instrument design, its abilities, its deployment during SUCCESS and the data acquired from the mission, and the post-mission calibration, data reduction, and analysis.

Using instrumental variables to estimate a Cox's proportional hazards regression subject to additive confounding

PubMed Central

Tosteson, Tor D.; Morden, Nancy E.; Stukel, Therese A.; O'Malley, A. James

2014-01-01

The estimation of treatment effects is one of the primary goals of statistics in medicine. Estimation based on observational studies is subject to confounding. Statistical methods for controlling bias due to confounding include regression adjustment, propensity scores and inverse probability weighted estimators. These methods require that all confounders are recorded in the data. The method of instrumental variables (IVs) can eliminate bias in observational studies even in the absence of information on confounders. We propose a method for integrating IVs within the framework of Cox's proportional hazards model and demonstrate the conditions under which it recovers the causal effect of treatment. The methodology is based on the approximate orthogonality of an instrument with unobserved confounders among those at risk. We derive an estimator as the solution to an estimating equation that resembles the score equation of the partial likelihood in much the same way as the traditional IV estimator resembles the normal equations. To justify this IV estimator for a Cox model we perform simulations to evaluate its operating characteristics. Finally, we apply the estimator to an observational study of the effect of coronary catheterization on survival. PMID:25506259

Using instrumental variables to estimate a Cox's proportional hazards regression subject to additive confounding.

PubMed

MacKenzie, Todd A; Tosteson, Tor D; Morden, Nancy E; Stukel, Therese A; O'Malley, A James

2014-06-01

The estimation of treatment effects is one of the primary goals of statistics in medicine. Estimation based on observational studies is subject to confounding. Statistical methods for controlling bias due to confounding include regression adjustment, propensity scores and inverse probability weighted estimators. These methods require that all confounders are recorded in the data. The method of instrumental variables (IVs) can eliminate bias in observational studies even in the absence of information on confounders. We propose a method for integrating IVs within the framework of Cox's proportional hazards model and demonstrate the conditions under which it recovers the causal effect of treatment. The methodology is based on the approximate orthogonality of an instrument with unobserved confounders among those at risk. We derive an estimator as the solution to an estimating equation that resembles the score equation of the partial likelihood in much the same way as the traditional IV estimator resembles the normal equations. To justify this IV estimator for a Cox model we perform simulations to evaluate its operating characteristics. Finally, we apply the estimator to an observational study of the effect of coronary catheterization on survival.

A New IMS Based Inter-working Solution

NASA Astrophysics Data System (ADS)

Zhu, Zhongwen; Brunner, Richard

With the evolution of third generation network, more and more multimedia services are developed and deployed. Any new service to be deployed in IMS network is required to inter-work with existing Internet communities or legacy terminal users in order to appreciate the end users, who are the main drivers for the service to succeed. The challenge for Inter-working between IMS (IP Multimedia Subsystem) and non-IMS network is “how to handle recipient’s address”. This is because each network has its own routable address schema. For instance, the address for Google Talk user is xmpp:xyz@google.com, which is un-routable in IMS network. Hereafter a new Inter-working (IW) solution between IMS and non-IMS network is proposed for multimedia services that include Instant Messaging, Chat, and File transfer, etc. It is an end-to-end solution built on IMS infrastructure. The Public Service Identity (PSI) defined in 3GPP standard (3rd Generation Partnership Project) is used to allow terminal clients to allocate this IW service. When sending the SIP (Session Initial Protocol) request out for multimedia services, the terminal includes the recipient’s address in the payload instead of the “Request-URI” header. In the network, the proposed solution provides the mapping rules between different networks in MM-IW (Multimedia IW). The detailed technical description and the corresponding use cases are present. The comparison with other alternatives is made. The benefits of the proposed solution are highlighted.

Simulating the hydrological impacts of inter-annual and seasonal variability in land use land cover change on streamflow

NASA Astrophysics Data System (ADS)

Taxak, A. K.; Ojha, C. S. P.

2017-12-01

Land use and land cover (LULC) changes within a watershed are recognised as an important factor affecting hydrological processes and water resources. LULC changes continuously not only in long term but also on the inter-annual and season level. Changes in LULC affects the interception, storage and moisture. A widely used approach in rainfall-runoff modelling through Land surface models (LSM)/ hydrological models is to keep LULC same throughout the model running period. In long term simulations where land use change take place during the run period, using a single LULC does not represent a true picture of ground conditions could result in stationarity of model responses. The present work presents a case study in which changes in LULC are incorporated by using multiple LULC layers. LULC for the study period were created using imageries from Landsat series, Sentinal, EO-1 ALI. Distributed, physically based Variable Infiltration Capacity (VIC) model was modified to allow inclusion of LULC as a time varying variable just like climate. The Narayani basin was simulated with LULC, leaf area index (LAI), albedo and climate data for 1992-2015. The results showed that the model simulation with varied parametrization approach has a large improvement over the conventional fixed parametrization approach in terms of long-term water balance. The proposed modelling approach could improve hydrological modelling for applications like land cover change studies, water budget studies etc.

iPod touch-assisted instrumentation of the spine: a technical report.

PubMed

Jost, Gregory F; Bisson, Erica F; Schmidt, Meic H

2013-12-01

Instrumentation of the spine depends on choosing the correct insertion angles to implant screws. Although modern image guidance facilitates precise instrumentation of the spine, the equipment is costly and availability is limited. Although most surgeons use lateral fluoroscopy to guide instrumentation in the sagittal plane, the lateromedial angulation is often chosen by estimation. To overcome the associated uncertainty, iPod touch-based applications for measuring angles can be used to assist with screw implantation. To evaluate the use of the iPod touch to adjust instruments to the optimal axial insertion angle for placement of pedicle screws in the lumbar spine. Twenty lumbar pedicle screws in 5 consecutive patients were implanted using the iPod touch. The lateromedial angulation was measured on preoperative images and reproduced in the operative field with the iPod touch. The instruments to implant the screws were aligned with the side of the iPod for screw insertion. Actual screw angles were remeasured on postoperative imaging. We collected demographic, clinical, and operative data for each patient. In 16 of 20 screws, the accuracy of implantation was within 3 degrees of the ideal trajectory. The 4 screws with an angle mismatch of 7 to 13 degrees were all implanted at the caudal end of the exposure, where maintaining the planned angulation was impeded by strong muscles pushing medially. iPod touch-assisted instrumentation of the spine is a very simple technique, which, in combination with a lateral fluoroscopy, may guide placement of pedicle screws in the lumbar spine.

Biasogram: Visualization of Confounding Technical Bias in Gene Expression Data

PubMed Central

Krzystanek, Marcin; Szallasi, Zoltan; Eklund, Aron C.

2013-01-01

Gene expression profiles of clinical cohorts can be used to identify genes that are correlated with a clinical variable of interest such as patient outcome or response to a particular drug. However, expression measurements are susceptible to technical bias caused by variation in extraneous factors such as RNA quality and array hybridization conditions. If such technical bias is correlated with the clinical variable of interest, the likelihood of identifying false positive genes is increased. Here we describe a method to visualize an expression matrix as a projection of all genes onto a plane defined by a clinical variable and a technical nuisance variable. The resulting plot indicates the extent to which each gene is correlated with the clinical variable or the technical variable. We demonstrate this method by applying it to three clinical trial microarray data sets, one of which identified genes that may have been driven by a confounding technical variable. This approach can be used as a quality control step to identify data sets that are likely to yield false positive results. PMID:23613961

Sweat Sodium Concentration: Inter-Unit Variability of a Low Cost, Portable, and Battery Operated Sodium Analyzer.

PubMed

Goulet, Eric D B; Baker, Lindsay B

2017-12-01

The B-722 Laqua Twin is a low cost, portable, and battery operated sodium analyzer, which can be used for the assessment of sweat sodium concentration. The Laqua Twin is reliable and provides a degree of accuracy similar to more expensive analyzers; however, its interunit measurement error remains unknown. The purpose of this study was to compare the sodium concentration values of 70 sweat samples measured using three different Laqua Twin units. Mean absolute errors, random errors and constant errors among the different Laqua Twins ranged respectively between 1.7 mmol/L to 3.5 mmol/L, 2.5 mmol/L to 3.7 mmol/L and -0.6 mmol/L to 3.9 mmol/L. Proportional errors among Laqua Twins were all < 2%. Based on a within-subject biological variability in sweat sodium concentration of ± 12%, the maximal allowable imprecision among instruments was considered to be £ 6%. In that respect, the within (2.9%), between (4.5%), and total (5.4%) measurement error coefficient of variations were all < 6%. For a given sweat sodium concentration value, the largest observed difference in mean and lower and upper bound error of measurements among instruments were, respectively, 4.7 mmol/L, 2.3 mmol/L, and 7.0 mmol/L. In conclusion, our findings show that the interunit measurement error of the B-722 Laqua Twin is low and methodologically acceptable.

Contracting Officer's Technical Representatives

NASA Technical Reports Server (NTRS)

Brisbin, Steve

1997-01-01

The Breakout Session is a traditional conference instrument used by the NASA Occupational Health Program (OHP) as a method to convene people with common interests. Typically these sessions provide discussion of current topics of high priority and currency and allow multiple views and opinions to be shared and evaluated by all participants. Since the Contracting Officer's Technical Representatives (COTRs) occupy the technical focus of support contract management, this particular group, attended by 20 representatives, addressed issues and topics at the forefront of operational concerns.

Instrumentation at Paranal Observatory: maintaining the instrument suite of five large telescopes and its interferometer alive

NASA Astrophysics Data System (ADS)

Gillet, Gordon; Alvarez, José Luis; Beltrán, Juan; Bourget, Pierre; Castillo, Roberto; Diaz, Álvaro; Haddad, Nicolás; Leiva, Alfredo; Mardones, Pedro; O'Neal, Jared; Ribes, Mauricio; Riquelme, Miguel; Robert, Pascal; Rojas, Chester; Valenzuela, Javier

2010-07-01

This presentation provides interesting miscellaneous information regarding the instrumentation activities at Paranal Observatory. It introduces the suite of 23 instruments and auxiliary systems that are under the responsibility of the Paranal Instrumentation group, information on the type of instruments, their usage and downtime statistics. The data is based on comprehensive data recorded in the Paranal Night Log System and the Paranal Problem Reporting System whose principles are explained as well. The work organization of the 15 team members around the high number of instruments is laid out, which includes: - Maintaining older instruments with obsolete components - Receiving new instruments and supporting their integration and commissioning - Contributing to future instruments in their developing phase. The assignments of the Instrumentation staff to the actual instruments as well as auxiliary equipment (Laser Guide Star Facility, Mask Manufacturing Unit, Cloud Observation Tool) are explained with respect to responsibility and scheduling issues. The essential activities regarding hardware & software are presented, as well as the technical and organizational developments within the group towards its present and future challenges.

Climate Informed Economic Instruments to Enhance Urban Water Supply Resilience to Hydroclimatological Variability and Change

NASA Astrophysics Data System (ADS)

Brown, C.; Carriquiry, M.; Souza Filho, F. A.

2006-12-01

Hydroclimatological variability presents acute challenges to urban water supply providers. The impact is often most severe in developing nations where hydrologic and climate variability can be very high, water demand is unmet and increasing, and the financial resources to mitigate the social effects of that variability are limited. Furthermore, existing urban water systems face a reduced solution space, constrained by competing and conflicting interests, such as irrigation demand, recreation and hydropower production, and new (relative to system design) demands to satisfy environmental flow requirements. These constraints magnify the impacts of hydroclimatic variability and increase the vulnerability of urban areas to climate change. The high economic and social costs of structural responses to hydrologic variability, such as groundwater utilization and the construction or expansion of dams, create a need for innovative alternatives. Advances in hydrologic and climate forecasting, and the increasing sophistication and acceptance of incentive-based mechanisms for achieving economically efficient water allocation offer potential for improving the resilience of existing water systems to the challenge of variable supply. This presentation will explore the performance of a system of climate informed economic instruments designed to facilitate the reduction of hydroclimatologic variability-induced impacts on water-sensitive stakeholders. The system is comprised of bulk water option contracts between urban water suppliers and agricultural users and insurance indexed on reservoir inflows designed to cover the financial needs of the water supplier in situations where the option is likely to be exercised. Contract and insurance parameters are linked to forecasts and the evolution of seasonal precipitation and streamflow and designed for financial and political viability. A simulation of system performance is presented based on ongoing work in Metro Manila, Philippines. The

OPTION(5) versus OPTION(12) instruments to appreciate the extent to which healthcare providers involve patients in decision-making.

PubMed

Stubenrouch, Fabienne E; Pieterse, Arwen H; Falkenberg, Rijan; Santema, T Katrien B; Stiggelbout, Anne M; van der Weijden, Trudy; Aarts, J Annemijn W M; Ubbink, Dirk T

2016-06-01

The 12-item "observing patient involvement" (OPTION(12))-instrument is commonly used to assess the extent to which healthcare providers involve patients in health-related decision-making. The five-item version (OPTION(5)) claims to be a more efficient measure. In this study we compared the Dutch versions of the OPTION-instruments in terms of inter-rater agreement and correlation in outpatient doctor-patient consultations in various settings, to learn if we can safely switch to the shorter OPTION(5)-instrument. Two raters coded 60 audiotaped vascular surgery and oncology patient consultations using OPTION(12) and OPTION(5). Unweighted Cohen's kappa was used to compute inter-rater agreement on item-level. The association between the total scores of the two OPTION-instruments was investigated using Pearson's correlation coefficient (r) and a Bland & Altman plot. After fine-tuning the OPTION-manuals, inter-rater agreement for OPTION(12) and OPTION(5) was good to excellent (kappa range 0.69-0.85 and 0.63-0.72, respectively). Mean total scores were 23.7 (OPTION(12); SD=7.8) and 39.3 (OPTION(5); SD=12.7). Correlation between the total scores was high (r=0.71; p=0.01). OPTION(5) scored systematically higher with a wider range than OPTION(12). Both OPTION-instruments had a good inter-rater agreement and correlated well. OPTION(5) seems to differentiate better between various levels of patient involvement. The OPTION(5)-instrument is recommended for clinical application. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Mapping Variables.

ERIC Educational Resources Information Center

Stone, Mark H.; Wright, Benjamin D.; Stenner, A. Jackson

1999-01-01

Describes mapping variables, the principal technique for planning and constructing a test or rating instrument. A variable map is also useful for interpreting results. Provides several maps to show the importance and value of mapping a variable by person and item data. (Author/SLD)

Quantitative image feature variability amongst CT scanners with a controlled scan protocol

NASA Astrophysics Data System (ADS)

Ger, Rachel B.; Zhou, Shouhao; Chi, Pai-Chun Melinda; Goff, David L.; Zhang, Lifei; Lee, Hannah J.; Fuller, Clifton D.; Howell, Rebecca M.; Li, Heng; Stafford, R. Jason; Court, Laurence E.; Mackin, Dennis S.

2018-02-01

Radiomics studies often analyze patient computed tomography (CT) images acquired from different CT scanners. This may result in differences in imaging parameters, e.g. different manufacturers, different acquisition protocols, etc. However, quantifiable differences in radiomics features can occur based on acquisition parameters. A controlled protocol may allow for minimization of these effects, thus allowing for larger patient cohorts from many different CT scanners. In order to test radiomics feature variability across different CT scanners a radiomics phantom was developed with six different cartridges encased in high density polystyrene. A harmonized protocol was developed to control for tube voltage, tube current, scan type, pitch, CTDIvol, convolution kernel, display field of view, and slice thickness across different manufacturers. The radiomics phantom was imaged on 18 scanners using the control protocol. A linear mixed effects model was created to assess the impact of inter-scanner variability with decomposition of feature variation between scanners and cartridge materials. The inter-scanner variability was compared to the residual variability (the unexplained variability) and to the inter-patient variability using two different patient cohorts. The patient cohorts consisted of 20 non-small cell lung cancer (NSCLC) and 30 head and neck squamous cell carcinoma (HNSCC) patients. The inter-scanner standard deviation was at least half of the residual standard deviation for 36 of 49 quantitative image features. The ratio of inter-scanner to patient coefficient of variation was above 0.2 for 22 and 28 of the 49 features for NSCLC and HNSCC patients, respectively. Inter-scanner variability was a significant factor compared to patient variation in this small study for many of the features. Further analysis with a larger cohort will allow more thorough analysis with additional variables in the model to truly isolate the interscanner difference.

Software Framework for Controlling Unsupervised Scientific Instruments.

PubMed

Schmid, Benjamin; Jahr, Wiebke; Weber, Michael; Huisken, Jan

2016-01-01

Science outreach and communication are gaining more and more importance for conveying the meaning of today's research to the general public. Public exhibitions of scientific instruments can provide hands-on experience with technical advances and their applications in the life sciences. The software of such devices, however, is oftentimes not appropriate for this purpose. In this study, we describe a software framework and the necessary computer configuration that is well suited for exposing a complex self-built and software-controlled instrument such as a microscope to laymen under limited supervision, e.g. in museums or schools. We identify several aspects that must be met by such software, and we describe a design that can simultaneously be used to control either (i) a fully functional instrument in a robust and fail-safe manner, (ii) an instrument that has low-cost or only partially working hardware attached for illustration purposes or (iii) a completely virtual instrument without hardware attached. We describe how to assess the educational success of such a device, how to monitor its operation and how to facilitate its maintenance. The introduced concepts are illustrated using our software to control eduSPIM, a fluorescent light sheet microscope that we are currently exhibiting in a technical museum.

Inter-observer variability in the classification of ovarian cancer cell type using microscopy: a pilot study

NASA Astrophysics Data System (ADS)

Gavrielides, Marios A.; Ronnett, Brigitte M.; Vang, Russell; Seidman, Jeffrey D.

2015-03-01

Studies have shown that different cell types of ovarian carcinoma have different molecular profiles, exhibit different behavior, and that patients could benefit from typespecific treatment. Different cell types display different histopathology features, and different criteria are used for each cell type classification. Inter-observer variability for the task of classifying ovarian cancer cell types is an under-examined area of research. This study served as a pilot study to quantify observer variability related to the classification of ovarian cancer cell types and to extract valuable data for designing a validation study of digital pathology (DP) for this task. Three observers with expertise in gynecologic pathology reviewed 114 cases of ovarian cancer with optical microscopy, with specific guidelines for classifications into distinct cell types. For 93 cases all 3 pathologists agreed on the same cell type, for 18 cases 2 out of 3 agreed, and for 3 cases there was no agreement. Across cell types with a minimum sample size of 10 cases, agreement between all three observers was {91.1%, 80.0%, 90.0%, 78.6%, 100.0%, 61.5%} for the high grade serous carcinoma, low grade serous carcinoma, endometrioid, mucinous, clear cell, and carcinosarcoma cell types respectively. These results indicate that unanimous agreement varied over a fairly wide range. However, additional research is needed to determine the importance of these differences in comparison studies. These results will be used to aid in the design and sizing of such a study comparing optical and digital pathology. In addition, the results will help in understanding the potential role computer-aided diagnosis has in helping to improve the agreement of pathologists for this task.

Inter-individual variability in cortical excitability and motor network connectivity following multiple blocks of rTMS

PubMed Central

Nettekoven, Charlotte; Volz, Lukas J.; Leimbach, Martha; Pool, Eva-Maria; Rehme, Anne K.; Eickhoff, Simon B.; Fink, Gereon R.; Grefkes, Christian

2016-01-01

The responsiveness to non-invasive neuromodulation protocols shows high inter-individual variability, the reasons of which remain poorly understood. We here tested whether the response to intermittent theta-burst stimulation (iTBS) – an effective repetitive transcranial magnetic stimulation (rTMS) protocol for increasing cortical excitability – depends on network properties of the cortical motor system. We furthermore investigated whether the responsiveness to iTBS is dose-dependent. To this end, we used a sham-stimulation controlled, single-blinded within-subject design testing for the relationship between iTBS aftereffects and (i) motor-evoked potentials (MEPs) as well as (ii) resting-state functional connectivity (rsFC) in 16 healthy subjects. In each session, three blocks of iTBS were applied, separated by 15 min. We found that non-responders (subjects not showing an MEP increase of ≥10% after one iTBS block) featured stronger rsFC between the stimulated primary motor cortex (M1) and premotor areas before stimulation compared to responders. However, only the group of responders showed increases in rsFC and MEPs, while most non-responders remained close to baseline levels after all three blocks of iTBS. Importantly, there was still a large amount of variability in both groups. Our data suggest that responsiveness to iTBS at the local level (i.e., M1 excitability) depends upon the pre-interventional network connectivity of the stimulated region. Of note, increasing iTBS dose did not turn non-responders into responders. The finding that higher levels of pre-interventional connectivity precluded a response to iTBS could reflect a ceiling effect underlying non-responsiveness to iTBS at the systems level. PMID:26052083

[Stainless steels for medical instruments].

PubMed

Feofilov, R N

1981-01-01

Both in the USSR and abroad similar types of martensitic and austenitic stainless steel are used for the manufacture of medical instruments. Martensitic steel, the cheapest and most economically alloyed, has the best combination of properties necessary for medical instruments. The analysis of the Soviet and foreign experience in using different grades of steel for the production of medical instruments demonstrates the expediency and possibility of improving the quality of martensitic steel and rolled stock, as well as that of medical instruments manufactured from these materials, by improving, the operations of the metallurgical and technological processes and by specifying more precisely the requirements for medical instruments. The possibility and expediency of using, in some technically justified cases, lower grades of alloyed steel instead of grade 12X18H9T for clamps and other instruments made of stainless steel, as well as highly corrosive grades of steel for microinstruments, have been established.

Wetland inventory and variability over the last two decades at a global scale

NASA Astrophysics Data System (ADS)

Prigent, C.; Papa, F.; Aires, F.; Rossow, W. B.; Matthews, E.

2011-12-01

Remote sensing techniques employing visible, infrared, and microwave observations offer varying success in estimating wetlands and inundation extent and in monitoring their natural and anthropogenic variations. Low spatial resolution (e.g., 30 km) limits detection to large wetlands but has the advantage of frequent coverage. High spatial resolution (e.g., 100 m), while providing more environmental information, suffers from poor temporal resolution, with observations for just high/low water or warm/cold seasons. Most existing wetland data sets are limited to a few regions, for specific times in the year. The only global inventories of wetland dynamics over a long period of time is derived from a remote-sensing technique employing a suite of complementary satellite observations: it uses passive microwave land-surface microwave emissivities, scatterometer responses, and visible and near infrared reflectances. Combining observations from different instruments makes it possible to capitalize on their complementary strengths, and to extract maximum information about inundation characteristics. The technique is globally applicable without any tuning for particular environments. The satellite data are used to calculate monthly-mean inundated fractions of equal-area grid cells (0.25°x0.25° at the equator), taking into account the contribution of vegetation to the passive microwave signal (Prigent et al., 2001, 2007). Several adjustments to the initial technique have been applied to account for changes in satellite instruments (Papa et al., 2010). The resulting data set now covers 1993-2008 and has been carefully evaluated. We will present the inter-annual variability of the water surface extents under different environments, and relate these variations to other hydrological variables such as river height, precipitation, water runoff, or Grace data. Natural wetlands are the world's largest methane source and dominate the inter-annual variability of atmospheric methane

The Relationship between Seven Variables and the Use of U.S. Government Technical Reports by U.S. Aerospace Engineers and Scientists.

ERIC Educational Resources Information Center

Pinelli, Thomas E.; And Others

1991-01-01

Describes a project sponsored by the National Aeronautics and Space Administration (NASA) and the Department of Defense that investigated the relationship between the use of U.S. government technical reports by aerospace engineers and scientists and seven independent sociometric variables. The conceptual framework is explained, and relevant…

Atmospheric circulation patterns associated to the variability of River Ammer floods: evidence from observed and proxy data

NASA Astrophysics Data System (ADS)

Rimbu, N.; Czymzik, M.; Ionita, M.; Lohmann, G.; Brauer, A.

2015-09-01

The relationship between the frequency of River Ammer floods (southern Germany) and atmospheric circulation variability is investigated based on observational Ammer discharge data back to 1926 and a flood layer time series from varved sediments of the downstream Lake Ammersee for the pre-instrumental period back to 1766. A composite analysis reveals that, at synoptic time scales, observed River Ammer floods are associated with enhanced moisture transport from the Atlantic Ocean and the Mediterranean towards the Ammer region, a pronounced trough over Western Europe as well as enhanced potential vorticity at upper levels. We argue that this synoptic scale configuration can trigger heavy precipitation and floods in the Ammer region. Interannual to multidecadal increases in flood frequency as recorded in the instrumental discharge record are associated to a wave-train pattern extending from the North Atlantic to western Asia with a prominent negative center over western Europe. A similar atmospheric circulation pattern is associated to increases in flood layer frequency in the Lake Ammersee sediment record during the pre-instrumental period. We argue that the complete flood layer time-series from Lake Ammersee sediments covering the last 5500 years, contains information about atmospheric circulation variability on inter-annual to millennial time-scales.

The development and testing of a qualitative instrument designed to assess critical thinking

NASA Astrophysics Data System (ADS)

Clauson, Cynthia Louisa

This study examined a qualitative approach to assess critical thinking. An instrument was developed that incorporates an assessment process based on Dewey's (1933) concepts of self-reflection and critical thinking as problem solving. The study was designed to pilot test the critical thinking assessment process with writing samples collected from a heterogeneous group of students. The pilot test included two phases. Phase 1 was designed to determine the validity and inter-rater reliability of the instrument using two experts in critical thinking, problem solving, and literacy development. Validity of the instrument was addressed by requesting both experts to respond to ten questions in an interview. The inter-rater reliability was assessed by analyzing the consistency of the two experts' scorings of the 20 writing samples to each other, as well as to my scoring of the same 20 writing samples. Statistical analyses included the Spearman Rho and the Kuder-Richardson (Formula 20). Phase 2 was designed to determine the validity and reliability of the critical thinking assessment process with seven science teachers. Validity was addressed by requesting the teachers to respond to ten questions in a survey and interview. Inter-rater reliability was addressed by comparing the seven teachers' scoring of five writing samples with my scoring of the same five writing samples. Again, the Spearman Rho and the Kuder-Richardson (Formula 20) were used to determine the inter-rater reliability. The validity results suggest that the instrument is helpful as a guide for instruction and provides a systematic method to teach and assess critical thinking while problem solving with students in the classroom. The reliability results show the critical thinking assessment instrument to possess fairly high reliability when used by the experts, but weak reliability when used by classroom teachers. A major conclusion was drawn that teachers, as well as students, would need to receive instruction

Characterization of Chinese body skin through in vivo instrument assessments, visual evaluations, and questionnaire: influences of body area, inter-generation, season, sex, and skin care habits.

PubMed

Li, Xi; Galzote, Carlos; Yan, Xiuyuan; Li, Li; Wang, Xi

2014-02-01

The varying influence of multiple factors (e.g., aging, sex, season, skin care habits) on skin structure and function necessitates study within ethnic groups to fully characterize their skin. Men and women aged 40-50 years (n = 43) and their consanguineous same-sex children, aged 18-25 years (n = 43), living in Chengdu, China were enrolled in this single center, non-interventional study. Volunteers attended two study visits (summer, 2010 and winter, 2011) at which dermatologists measured transepidermal water loss (TEWL), skin hydration, sebum secretion, fine lines/roughness, melanin/erythema, temperature, and color, and clinically graded participants' skin. Participants answered a questionnaire, indicating their perceived skin type/condition. Data were analyzed using t-test/anova or Friedman/Wilcoxon test. Objective measurements demonstrated statistically significant inter-generational differences in skin condition, with aged skin more wrinkled at most sites, having reduced oil/colder facial and décolletage skin, darker/more erythematous skin in exposed areas, and less hydrated/rougher heel skin; similarities were detected in skin melanin, erythema, and TEWL. There were also statistically significant differences between seasons and sexes. The intersection between instrument measurements and subjective perceptions of skin revealed notable differences. Objective measurements and their intersection with subjective perceptions demonstrate the influences of inter-generation, season, sex, and living habits on Chinese body skin. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Inter- and intra-population variability of the protein content of femoral gland secretions from a lacertid lizard

PubMed Central

Fumagalli, Marco; Scali, Stefano; Zuffi, Marco A L; Cagnone, Maddalena; Salvini, Roberta; Sacchi, Roberto

2017-01-01

Abstract Femoral glands of male lizards produce waxy secretions that are involved in inter- and intraspecific chemical communication. The main components of these secretions are proteins and lipids, the latter having been extensively studied and already associated to male quality. On the opposite, the composition and role of proteins are nearly unknown, the only available information coming from few studies on iguanids. These studies got the conclusion that proteins might have a communicative function, notably they could signal individual identity. A generalization of these findings requires the extension of protein analysis to other lizard families, and the primary detection of some patterns of individual variability. Using the common wall lizard Podarcis muralis as a model species, the protein fraction of the femoral pore secretions was investigated to provide the first characterization of this component in a lacertid lizard and to explore its source of variability, as a first step to support the hypothesized communicative role. Samples of proteins from femoral secretions were collected from 6 Italian populations and subjected to 1-dimensional electrophoresis. The binary vector of the band presence/absence was used to define the individual profiles. Protein fraction is found to have a structured pattern, with both an individual and a population component. Although the former supports the potential communicative role of proteins, the latter offers a double interpretation, phylogenetic or environmental, even though the phylogenetic effect seems more likely given the climatic resemblance of the considered sites. Further studies are necessary to shed light on both these issues. PMID:29492027

Inter-laboratory comparison study on measuring semi-volatile organic chemicals in standards and air samples.

PubMed

Su, Yushan; Hung, Hayley

2010-11-01

Measurements of semi-volatile organic chemicals (SVOCs) were compared among 21 laboratories from 7 countries through the analysis of standards, a blind sample, an air extract, and an atmospheric dust sample. Measurement accuracy strongly depended on analytes, laboratories, and types of standards and samples. Intra-laboratory precision was generally good with relative standard deviations (RSDs) of triplicate injections <10% and with median differences of duplicate samples between 2.1 and 22%. Inter-laboratory variability, measured by RSDs of all measurements, was in the range of 2.8-58% in analyzing standards, and 6.9-190% in analyzing blind sample and air extract. Inter-laboratory precision was poorer when samples were subject to cleanup processes, or when SVOCs were quantified at low concentrations. In general, inter-laboratory differences up to a factor of 2 can be expected to analyze atmospheric SVOCs. When comparing air measurements from different laboratories, caution should be exercised if the data variability is less than the inter-laboratory differences. 2010. Published by Elsevier Ltd. All rights reserved.

THE DEVELOPMENT AND INTER-LABORATORY VERIFICATION OF LC-MS LIBRARIES FOR ORGANIC CHEMICALS OF ENVIRONMENTAL CONCERN

EPA Science Inventory

The development, verification, and comparison study between LC-MS libraries for two manufacturers’ instruments and a verified protocol are discussed. The LC-MS library protocol was verified through an inter-laboratory study that involved Federal, State, and private laboratories. ...

Investigating Inter-Individual Differences in Short-Term Intra-Individual Variability

ERIC Educational Resources Information Center

Wang, Lijuan; Hamaker, Ellen; Bergeman, C. S.

2012-01-01

Intra-individual variability over a short period of time may contain important information about how individuals differ from each other. In this article we begin by discussing diverse indicators for quantifying intra-individual variability and indicate their advantages and disadvantages. Then we propose an alternative method that models…

Instrumental variables estimates of peer effects in social networks.

PubMed

An, Weihua

2015-03-01

Estimating peer effects with observational data is very difficult because of contextual confounding, peer selection, simultaneity bias, and measurement error, etc. In this paper, I show that instrumental variables (IVs) can help to address these problems in order to provide causal estimates of peer effects. Based on data collected from over 4000 students in six middle schools in China, I use the IV methods to estimate peer effects on smoking. My design-based IV approach differs from previous ones in that it helps to construct potentially strong IVs and to directly test possible violation of exogeneity of the IVs. I show that measurement error in smoking can lead to both under- and imprecise estimations of peer effects. Based on a refined measure of smoking, I find consistent evidence for peer effects on smoking. If a student's best friend smoked within the past 30 days, the student was about one fifth (as indicated by the OLS estimate) or 40 percentage points (as indicated by the IV estimate) more likely to smoke in the same time period. The findings are robust to a variety of robustness checks. I also show that sharing cigarettes may be a mechanism for peer effects on smoking. A 10% increase in the number of cigarettes smoked by a student's best friend is associated with about 4% increase in the number of cigarettes smoked by the student in the same time period. Copyright © 2014 Elsevier Inc. All rights reserved.

Evaluating Written Patient Information for Eczema in German: Comparing the Reliability of Two Instruments, DISCERN and EQIP

PubMed Central

McCool, Megan E.; Wahl, Josepha; Schlecht, Inga; Apfelbacher, Christian

2015-01-01

Patients actively seek information about how to cope with their health problems, but the quality of the information available varies. A number of instruments have been developed to assess the quality of patient information, primarily though in English. Little is known about the reliability of these instruments when applied to patient information in German. The objective of our study was to investigate and compare the reliability of two validated instruments, DISCERN and EQIP, in order to determine which of these instruments is better suited for a further study pertaining to the quality of information available to German patients with eczema. Two independent raters evaluated a random sample of 20 informational brochures in German. All the brochures addressed eczema as a disorder and/or therapy options and care. Intra-rater and inter-rater reliability were assessed by calculating intra-class correlation coefficients, agreement was tested with weighted kappas, and the correlation of the raters’ scores for each instrument was measured with Pearson’s correlation coefficient. DISCERN demonstrated substantial intra- and inter-rater reliability. It also showed slightly better agreement than EQIP. There was a strong correlation of the raters’ scores for both instruments. The findings of this study support the reliability of both DISCERN and EQIP. However, based on the results of the inter-rater reliability, agreement and correlation analyses, we consider DISCERN to be the more precise tool for our project on patient information concerning the treatment and care of eczema. PMID:26440612

Evaluating Written Patient Information for Eczema in German: Comparing the Reliability of Two Instruments, DISCERN and EQIP.

PubMed

McCool, Megan E; Wahl, Josepha; Schlecht, Inga; Apfelbacher, Christian

2015-01-01

Patients actively seek information about how to cope with their health problems, but the quality of the information available varies. A number of instruments have been developed to assess the quality of patient information, primarily though in English. Little is known about the reliability of these instruments when applied to patient information in German. The objective of our study was to investigate and compare the reliability of two validated instruments, DISCERN and EQIP, in order to determine which of these instruments is better suited for a further study pertaining to the quality of information available to German patients with eczema. Two independent raters evaluated a random sample of 20 informational brochures in German. All the brochures addressed eczema as a disorder and/or therapy options and care. Intra-rater and inter-rater reliability were assessed by calculating intra-class correlation coefficients, agreement was tested with weighted kappas, and the correlation of the raters' scores for each instrument was measured with Pearson's correlation coefficient. DISCERN demonstrated substantial intra- and inter-rater reliability. It also showed slightly better agreement than EQIP. There was a strong correlation of the raters' scores for both instruments. The findings of this study support the reliability of both DISCERN and EQIP. However, based on the results of the inter-rater reliability, agreement and correlation analyses, we consider DISCERN to be the more precise tool for our project on patient information concerning the treatment and care of eczema.

Relationship between intraoperative non-technical performance and technical events in bariatric surgery.

PubMed

Fecso, A B; Kuzulugil, S S; Babaoglu, C; Bener, A B; Grantcharov, T P

2018-03-30

The operating theatre is a unique environment with complex team interactions, where technical and non-technical performance affect patient outcomes. The correlation between technical and non-technical performance, however, remains underinvestigated. The purpose of this study was to explore these interactions in the operating theatre. A prospective single-centre observational study was conducted at a tertiary academic medical centre. One surgeon and three fellows participated as main operators. All patients who underwent a laparoscopic Roux-en-Y gastric bypass and had the procedures captured using the Operating Room Black Box ® platform were included. Technical assessment was performed using the Objective Structured Assessment of Technical Skills and Generic Error Rating Tool instruments. For non-technical assessment, the Non-Technical Skills for Surgeons (NOTSS) and Scrub Practitioners' List of Intraoperative Non-Technical Skills (SPLINTS) tools were used. Spearman rank-order correlation and N-gram statistics were conducted. Fifty-six patients were included in the study and 90 procedural steps (gastrojejunostomy and jejunojejunostomy) were analysed. There was a moderate to strong correlation between technical adverse events (r s  = 0·417-0·687), rectifications (r s  = 0·380-0·768) and non-technical performance of the surgical and nursing teams (NOTSS and SPLINTS). N-gram statistics showed that after technical errors, events and prior rectifications, the staff surgeon and the scrub nurse exhibited the most positive non-technical behaviours, irrespective of operator (staff surgeon or fellow). This study demonstrated that technical and non-technical performances are related, on both an individual and a team level. Valuable data can be obtained around intraoperative errors, events and rectifications. © 2018 BJS Society Ltd Published by John Wiley & Sons Ltd.

The Cerro Tololo Inter-American Observatory Summer Student Programs in La Serena, Chile

NASA Astrophysics Data System (ADS)

Kaleida, Catherine C.; Smith, C.; Van Der Bliek, N. S.; James, D.

2014-01-01

The Cerro Tololo Inter-American Observatory (CTIO) offers positions for U.S. and Chilean student interns during the Chilean summer months of January-March (northern winter semester) at the CTIO offices in La Serena, Chile. CTIO is part of the National Optical Astronomy Observatory (NOAO) of the United States, focused on the development of astronomy in the southern hemisphere. Six undergraduate research assistantships are offered for U.S. physics and astronomy undergraduate students through the NSF-funded Research Experiences for Undergraduates (REU) program. The CTIO-funded Prácticas de Investigación en Astronomía (PIA) program is run concurrently with the REU program, and offers two research assistantships for Chilean undergraduate or 1st or 2nd year masters students, also at the CTIO offices in La Serena, Chile. The CTIO REU and PIA programs provide exceptional opportunities for students considering a career in astronomy to engage in substantive research activities with scientists working at the forefront of contemporary astrophysics. Student participants work on specific research projects in close collaboration with members of the CTIO scientific and technical staff, such as galaxy clusters, gravitational lensing, supernovae, planetary nebulae, stellar populations, star clusters, star formation, variable stars and interstellar medium. The CTIO REU and PIA programs emphasize observational techniques and provide opportunities for direct observational experience using CTIO's state-of-the-art telescopes and instrumentation. The programs run for 10 weeks, from mid-January to the end of March. A two-night observing run on Cerro Tololo and a field trip to another observatory in Chile are included for students of both programs. These positions are full time, and those selected will receive a modest stipend and subsidized housing on the grounds of the offices of CTIO in La Serena, as well as travel costs to and from La Serena. In addition, the students have the

Instrumental variable specifications and assumptions for longitudinal analysis of mental health cost offsets.

PubMed

O'Malley, A James

2012-12-01

Instrumental variables (IVs) enable causal estimates in observational studies to be obtained in the presence of unmeasured confounders. In practice, a diverse range of models and IV specifications can be brought to bear on a problem, particularly with longitudinal data where treatment effects can be estimated for various functions of current and past treatment. However, in practice the empirical consequences of different assumptions are seldom examined, despite the fact that IV analyses make strong assumptions that cannot be conclusively tested by the data. In this paper, we consider several longitudinal models and specifications of IVs. Methods are applied to data from a 7-year study of mental health costs of atypical and conventional antipsychotics whose purpose was to evaluate whether the newer and more expensive atypical antipsychotic medications lead to a reduction in overall mental health costs.

Inter-individual variability in cortical excitability and motor network connectivity following multiple blocks of rTMS.

PubMed

Nettekoven, Charlotte; Volz, Lukas J; Leimbach, Martha; Pool, Eva-Maria; Rehme, Anne K; Eickhoff, Simon B; Fink, Gereon R; Grefkes, Christian

2015-09-01

The responsiveness to non-invasive neuromodulation protocols shows high inter-individual variability, the reasons of which remain poorly understood. We here tested whether the response to intermittent theta-burst stimulation (iTBS) - an effective repetitive transcranial magnetic stimulation (rTMS) protocol for increasing cortical excitability - depends on network properties of the cortical motor system. We furthermore investigated whether the responsiveness to iTBS is dose-dependent. To this end, we used a sham-stimulation controlled, single-blinded within-subject design testing for the relationship between iTBS aftereffects and (i) motor-evoked potentials (MEPs) as well as (ii) resting-state functional connectivity (rsFC) in 16 healthy subjects. In each session, three blocks of iTBS were applied, separated by 15min. We found that non-responders (subjects not showing an MEP increase of ≥10% after one iTBS block) featured stronger rsFC between the stimulated primary motor cortex (M1) and premotor areas before stimulation compared to responders. However, only the group of responders showed increases in rsFC and MEPs, while most non-responders remained close to baseline levels after all three blocks of iTBS. Importantly, there was still a large amount of variability in both groups. Our data suggest that responsiveness to iTBS at the local level (i.e., M1 excitability) depends upon the pre-interventional network connectivity of the stimulated region. Of note, increasing iTBS dose did not turn non-responders into responders. The finding that higher levels of pre-interventional connectivity precluded a response to iTBS could reflect a ceiling effect underlying non-responsiveness to iTBS at the systems level. Copyright © 2015 Elsevier Inc. All rights reserved.

Combined role of heat and water stresses on wheat, maize and rice inter-annual variability and trend from 1980 to 2010.

NASA Astrophysics Data System (ADS)

Zampieri, M.; Ceglar, A., , Dr; Dentener, F., , Dr; van den Berg, M., , Dr; Toreti, A., , Dr

2017-12-01

Heat waves and drought are often considered the most damaging climatic stressors for wheat and maize. In this study, based on data derived from observations, we characterize and attribute the effects of these climate extremes on wheat and maize yield anomalies (at global and national scales) with respect to the mean trend from 1980 to 2010. Using a combination of up-to-date heat wave and drought indexes (i.e. the Heat Magnitude Day, HMD, and the Standardized Precipitation Evapotranspiration Index, SPEI), we have developed a composite indicator (i.e. the Combined Stress Index, CSI) that is able to capture the spatio-temporal characteristics of the underlying physical processes in the different agro-climatic regions of the world. At the global level, our diagnostic explains the 42% and the 50% of the inter-annual wheat and maize production variabilities, respectively. The relative importance of heat stress and drought in determining the yield anomalies depends on the region. Compared to maize, and in contrast to common perception, water excess affects wheat production more than drought in several countries. The index definition can be modified in order to quantify the role of combined heat and water stress events occurrence in determining the recorded yield trends as well. Climate change is increasingly limiting maize yields in several countries, especially in Europe and China. A comparable opposite signal, albeit less statistically significant, is found for the USA, which is the main world producer. As for rice, we provide a statistical evidence pointing out to the importance of considering the interactions with the horizontal surface waters fluxes carried out by the rivers. In fact, compared to wheat and maize, the CSI statistical skills in explaining rice production variability are quite reduced. This issue is particularly relevant in paddy fields and flooded lowlands where rice is mainly grown. Therefore, we have modified the procedure including a proxy for the

Interindividual variability of electromyographic patterns and pedal force profiles in trained cyclists.

PubMed

Hug, François; Drouet, Jean Marc; Champoux, Yvan; Couturier, Antoine; Dorel, Sylvain

2008-11-01

The aim of this study was to determine whether high inter-individual variability of the electromyographic (EMG) patterns during pedaling is accompanied by variability in the pedal force application patterns. Eleven male experienced cyclists were tested at two submaximal power outputs (150 and 250 W). Pedal force components (effective and total forces) and index of mechanical effectiveness were measured continuously using instrumented pedals and were synchronized with surface electromyography signals measured in ten lower limb muscles. The intersubject variability of EMG and mechanical patterns was assessed using standard deviation, mean deviation, variance ratio and coefficient of cross-correlation (_R(0), with lag time = 0). The results demonstrated a high intersubject variability of EMG patterns at both exercise intensities for biarticular muscles as a whole (and especially for Gastrocnemius lateralis and Rectus femoris) and for one monoarticular muscle (Tibialis anterior). However, this heterogeneity of EMG patterns is not accompanied by a so high intersubject variability in pedal force application patterns. A very low variability in the three mechanical profiles (effective force, total force and index of mechanical effectiveness) was obtained in the propulsive downstroke phase, although a greater variability in these mechanical patterns was found during upstroke and around the top dead center, and at 250 W when compared to 150 W. Overall, these results provide additional evidence for redundancy in the neuromuscular system.

Atmospheric Research 2011 Technical Highlights

NASA Technical Reports Server (NTRS)

2012-01-01

The 2011 Technical Highlights describes the efforts of all members of Atmospheric Research. Their dedication to advancing Earth Science through conducting research, developing and running models, designing instruments, managing projects, running field campaigns, and numerous other activities, is highlighted in this report.