Number Of Available Instruments Research Articles

Factor IV Estimation in Conditional Moment Models with an Application to Inflation Dynamics

Abstract In a conditional moment model, we develop a new integrated conditional moment (ICM) estimator which directly exploits factor-based conditional moment restrictions without having to first parametrize, or estimate such restrictions. We focus on a time series framework where the large number of available instruments and associated lags is driven by a relatively small number of unobserved factors. We build on the ICM principle originally proposed by Bierens (1982) and combine it with information reduction methods to handle the large number of potential instruments which may exceed the sample size. Under the maintained validity of the true factors, but not that of observed instruments, and standard regularity assumptions, our estimator is consistent, asymptotically normally distributed, and easy to compute. In our simulation studies, we document its reliability and power in cases where the underlying relationship between the endogenous variables and the instruments may be heterogeneous, non-linear, or even unstable over time. Our estimation of the New Keynesian Phillips curve with U.S. data reveals that forward- and backward-looking behaviors are quantitatively equally as important, while the driver’s role is nil.

Neutron scattering: A subsurface application review

Geomaterials and filling fluids properties that are pertinent to a geologic porous media can be characterized using a range of methods, such as nuclear magnetic resonance, X-rays, infrared spectroscopy, and neutron scattering (NS). In this context, NS features as an important tool elucidate key properties of a porous medium, which has recently gained significant attention. Key rock properties that can be measured by NS include: rock texture (i.e. crystallographic preferred orientation), mechanical properties (i.e. stress and strain) as well as porous medium properties (pore porosity, pore size and connectivity). In addition, NS imaging can help elucidate the phase behaviour of confined reservoir fluids in rock matrix under prevailing pressures and temperatures. Thus, a precise characterization of these properties (amongst other multiphase flow attributes) is critical for several applications in varied fields such as hydrocarbon reservoirs, geothermal systems, crystallography, geomechanics and geochemistry. Low neutron attenuation by most substances (deep sample penetration) and strong neutron attenuation by hydrogen are essential features of neutrons that allow NS to collect high-quality data across a wide variety of subsurface conditions. These features enable NS to be ideally suited to some applications as compared to other techniques such as X-rays and magnetic resonance imaging (MRI). For example, X-rays may not have sufficient resolutions for examining nanopore structures and confined fluids. Contrastingly, MRI is limited by the visualization of a range of pore sizes. However, NS can capture angstrom-to-micron-scale information of atomic to meso-to-macro-scale structures of rocks and fluids (i.e. hydrogen-rich fluids) inside a porous medium. These insights are vital for predictive reservoir models, where meaningful reservoir-scale (hectometre-scale) predictions can be performed. However, when compared to X-rays, neutrons have weak sources and/or low signals; therefore, experimental time can be quite long and samples need to be relatively large. Other limitations of NS (some may be also true of other techniques) include problems like accessing neutron sources (e.g. complicated nuclear processes for neutron production and small number of available instruments when compared to X-rays), high costs, and the strong absorption of neutron signals by some elements [e.g. cadmium (Cd), boron (B), and gadolinium (Gd)]. Despite the potential of NS, a review that considers key NS subsurface applications, limitations, and outlooks is currently lacking. Thus, in this review, we describe the basic concepts, experiments, methods, requirements, restrictions, and applications of NS for rock and fluid characterization. This study finds that despite its overall challenges, NS is a promising technique for characterizing subsurface rock and fluid systems, opening diverse avenues for future technological and scientific research within this area.

The AMAGAMI technique: an easy technique to achieve precise stapling in thoracoscopic segmentectomy.

The "AMAGAMI" or "incomplete grasping" technique is used to adjust the location of the lung while gently grasping the lung tissue with a stapler. Thoracoscopic segmentectomy requires precise but complex stapling, while the surgical view and the number of available instruments are limited. In the AMAGAMI technique, instead of moving the stapler to the targeted position of the lung tissue, an unlocked stapler is used to hold the lung tissue at an easily accessible position, and the lung tissue can then be slid to the ideal resection line using forceps. To use the AMAGAMI technique effectively, "standing stitches" are very helpful in enabling visualization of the ideal resection lines. Standing stitches are placed along intersegmental lines that have been determined based on the information provided by virtual-assisted lung mapping (VAL-MAP) or other marking techniques; these stiches are usually placed at the corner of the targeted segment and in-between if necessary. Monofilament suture is used for standing stitches, and about 1 cm lengths are left to enable later visualization. As these stitches stick out of the lung surface even when viewed from a tangential angle, the direction of stapling is easily visualized in thoracoscopic surgery. These techniques are particularly useful in challenging segmentectomy requiring complex staple lines, such as S10 segmentectomy, and in surgery with limited instrumental access, such as uniportal thoracoscopic surgery.

Systemic inflammation and causal risk for Alzheimer's dementia: Possibilities and limitations of a Mendelian randomization approach.

Epidemiological studies have implicated systemic inflammation in the development of Alzheimer's disease (AD). However, these observations have been subject to residual confounding and reverse causation. We applied Mendelian randomization approaches to address this. We did not identify any causal associations between serum interleukin (IL)‐18, IL‐1ra, IL‐6, or erythrocyte sedimentation rate (ESR) concentrations and AD. Our findings are limited by the low number of available instruments, though some of those identified (e.g., IL‐6) were of sufficient power to indicate true negative results. Taken together, it appears there is no evidence for a causal association between these serum inflammatory cytokines and AD.

Outcomes for implementation science: an enhanced systematic review of instruments using evidence-based rating criteria.

BackgroundHigh-quality measurement is critical to advancing knowledge in any field. New fields, such as implementation science, are often beset with measurement gaps and poor quality instruments, a weakness that can be more easily addressed in light of systematic review findings. Although several reviews of quantitative instruments used in implementation science have been published, no studies have focused on instruments that measure implementation outcomes. Proctor and colleagues established a core set of implementation outcomes including: acceptability, adoption, appropriateness, cost, feasibility, fidelity, penetration, sustainability (Adm Policy Ment Health Ment Health Serv Res 36:24–34, 2009). The Society for Implementation Research Collaboration (SIRC) Instrument Review Project employed an enhanced systematic review methodology (Implement Sci 2: 2015) to identify quantitative instruments of implementation outcomes relevant to mental or behavioral health settings.MethodsFull details of the enhanced systematic review methodology are available (Implement Sci 2: 2015). To increase the feasibility of the review, and consistent with the scope of SIRC, only instruments that were applicable to mental or behavioral health were included. The review, synthesis, and evaluation included the following: (1) a search protocol for the literature review of constructs; (2) the literature review of instruments using Web of Science and PsycINFO; and (3) data extraction and instrument quality ratings to inform knowledge synthesis. Our evidence-based assessment rating criteria quantified fundamental psychometric properties as well as a crude measure of usability. Two independent raters applied the evidence-based assessment rating criteria to each instrument to generate a quality profile.ResultsWe identified 104 instruments across eight constructs, with nearly half (n = 50) assessing acceptability and 19 identified for adoption, with all other implementation outcomes revealing fewer than 10 instruments. Only one instrument demonstrated at least minimal evidence for psychometric strength on all six of the evidence-based assessment criteria. The majority of instruments had no information regarding responsiveness or predictive validity.ConclusionsImplementation outcomes instrumentation is underdeveloped with respect to both the sheer number of available instruments and the psychometric quality of existing instruments. Until psychometric strength is established, the field will struggle to identify which implementation strategies work best, for which organizations, and under what conditions.Electronic supplementary materialThe online version of this article (doi:10.1186/s13012-015-0342-x) contains supplementary material, which is available to authorized users.

Patient-Reported Outcome Instruments for Physical Symptoms Among Patients Receiving Maintenance Dialysis: A Systematic Review

Patients with end-stage renal disease (ESRD) receiving dialysis have poor health-related quality of life. Physical symptoms are highly prevalent among dialysis-dependent patients and play important roles in health-related quality of life. A range of symptom assessment tools have been used in dialysis-dependent patients, but there has been no previous systematic assessment of the existing symptom measures' content, validity, and reliability. Systematic review of the literature. Patients with ESRD on maintenance dialysis therapy. Instruments with 3 or more physical symptoms previously used in dialysis-dependent patients and evidence of validity or reliability testing. Patient-reported physical symptom assessment instrument. Instrument symptom-related content, validity, and reliability. From 3,148 screened abstracts, 89 full-text articles were eligible for review. After article exclusion and further article identification by reference reviews, 58 articles on 23 symptom assessment instruments with documented reliability or validity testing were identified. Of the assessment instruments, 43.5% were generic and 56.5% were ESRD specific. Symptoms most frequently assessed were fatigue, shortness of breath, insomnia, nausea and vomiting, and appetite. Instruments varied widely in respondent time burden, recall period, and symptom attributes. Few instruments considered recall periods less than 2 weeks and few assessed a range of symptom attributes. Psychometric testing was completed for congruent validity (70%), known-group validity (25%), responsiveness (30%), internal consistency (78%), and test-retest reliability (65%). Content validity was assessed in dialysis populations in 57% of the 23 instruments. Consideration of physical symptoms only and exclusion of single symptom-focused instruments. The number of available instruments focused exclusively on physical symptoms in dialysis patients is limited. Few symptom-containing instruments have short recall periods, assess diverse symptom attributes, and have undergone comprehensive psychometric testing. Improved symptom-focused assessment tools are needed to improve symptom evaluation and symptom responsiveness to intervention among dialysis-dependent patients.

Instrumental variables estimation with many weak instruments using regularized JIVE

We consider instrumental variables regression in models where the number of available instruments may be larger than the sample size and consistent model selection in the first stage may not be possible. Such a situation may arise when there are many weak instruments. With many weak instruments, existing approaches to first-stage regularization can lead to a large bias relative to standard errors. We propose a jackknife instrumental variables estimator (JIVE) with regularization at each jackknife iteration that helps alleviate this bias. We derive the limiting behavior for a ridge-regularized JIV estimator (RJIVE), verifying that the RJIVE is consistent and asymptotically normal under conditions which allow for more instruments than observations and do not require consistent model selection. We provide simulation results that demonstrate the proposed RJIVE performs favorably in terms of size of tests and risk properties relative to other many-weak instrument estimation strategies in high-dimensional settings. We also apply the RJIVE to the Angrist and Krueger (1991) example where it performs favorably relative to other many-instrument robust procedures.

Body image in Brazil: recent advances in the state of knowledge and methodological issues.

OBJECTIVETo analyze Brazilian literature on body image and the theoretical and methodological advances that have been made.METHODSA detailed review was undertaken of the Brazilian literature on body image, selecting published articles, dissertations and theses from the SciELO, SCOPUS, LILACS and PubMed databases and the CAPES thesis database. Google Scholar was also used. There was no start date for the search, which used the following search terms: “body image” AND “Brazil” AND “scale(s)”; “body image” AND “Brazil” AND “questionnaire(s)”; “body image” AND “Brazil” AND “instrument(s)”; “body image” limited to Brazil and “body image”.RESULTSThe majority of measures available were intended to be used in college students, with half of them evaluating satisfaction/dissatisfaction with the body. Females and adolescents of both sexes were the most studied population. There has been a significant increase in the number of available instruments. Nevertheless, numerous published studies have used non-validated instruments, with much confusion in the use of the appropriate terms (e.g., perception, dissatisfaction, distortion).CONCLUSIONSMuch more is needed to understand body image within the Brazilian population, especially in terms of evaluating different age groups and diversifying the components/dimensions assessed. However, interest in this theme is increasing, and important steps have been taken in a short space of time.

Patient-Reported Outcomes in Studies of Complementary and Alternative Medicine: Problems, Solutions, and Future Directions

Patient-reported outcome (PRO) measures are frequently used to assess therapeutic efficacy and effectiveness of complementary and alternative medicine (CAM). Although CAM investigators are increasingly making use of valid, self-report instruments to assess patient-relevant outcomes, the sheer number of available instruments poses challenges. Two of the more pressing issues are discussed: the lack of guidance for selecting measures and the limited attention paid to the clinical meaningfulness of PRO results. Solutions are offered that may support selection and standardization of outcome measures for future CAM studies. This includes testing of tools from the National Institutes of Health's Patient-Reported Outcomes Measurement Information System (PROMIS). Increased standardization of outcome measurement in CAM studies will allow for more cross-study comparisons and facilitate the statistical pooling of results, ultimately leading to a more informative evidence base.

Physical fitness in older people with ID—Concept and measuring instruments: A review

A certain level of physical fitness is a prerequisite for independent functioning and self-care, but the level of physical fitness declines with ageing. This applies to older adult with intellectual disabilities too, but very little is known about their actual level of physical fitness. This lack of knowledge is partly caused by a lack of suitable instruments to measure physical fitness in this group, but the search for and choice of instruments depends on the operationalisation of the concept physical fitness for specific this target population. In this article the advantages of two known definitions of physical fitness are combined, leading to a combination of seven components to describe physical fitness in older adults with intellectual disabilities: coordination, reaction time, balance, muscular strength, muscular endurance, flexibility and cardio-respiratory endurance. A literature search for all instruments to measure any of these components resulted in a large number of available instruments. These instruments were evaluated according criteria of functionality, reliability and feasibility in this target population. The aim of this article was to propose a selection of instruments which complied with these criteria and creates possibilities for widespread use and sharing and/or pooling of data. The proposed selection of tests to measure physical fitness in older adults with intellectual disabilities is: Box and Block test, Reaction time test with an auditive and visual signal, Berg balance scale, Walking speed comfortable and fast, Grip strength with a hand dynamometer, 30 s chair stand, modified back saver sit and reach and the 10 m incremental shuttle walking test.

Latent structure of learning goals and strategies

A review of the relevant literature demonstrates disagreement regarding the number and nature of factors that affect learning goals and strategies, as well as whether the goals and strategies may be treated as separate groups of phenomena. In order to clarify this controversy, a sample of 364 Belgrade University students was given an instrument consisting of 94 indicators taken from a larger number of available instruments that measure approaches to learning, goal orientations and learning strategies. Factor analysis, applied on the obtained data, showed that six first-order factors related to learning goals and seven first-order factors related to learning strategies explain the latent structure of the phenomenon. Then, second order factor analysis was applied on the pool of obtained factor scores. The assumption that learning goals and strategies share a similar latent structure was confirmed. The results show that a large number of these factors can be predominantly reduced to three latent dimensions: deep approach, surface approach, and achievement approach. The paper suggests that precise operationalisation of the achievement approach is required in the future research.

Experimental Analysis and Numerical Simulations of Waves and Current Flows Around Low-Crested Rubble-Mound Structures

The objective of this paper is to analyze flow patterns and velocity fields around rubble-mound low-crested structures based on wave basin experiments and 2DH numerical simulations. Experiments were performed in the 12.5×9.7m2 wave basin at Aalborg University, Denmark, within the framework of the EU-funded project DELOS. Two different layouts were designed: two detached breakwaters with a gap in between and an oblique breakwater forming a rip channel with the basin side wall. Both cases of narrow and wide berm were tested under two- and three-dimensional regular and irregular wave attacks. Fluxes around and through the structures are examined by means of image analysis and measurements of free surface elevation and velocity at fixed locations. An original scheme for evaluating the overtopping discharge through a wave-by-wave analysis of wave gauge records over the barrier is described. Overtopping discharges are reconstructed and related to existing wave run-up models for emerged and zero-freeboard structures. Since no measurement was performed in the rubble mound, a “scale” model to estimate filtration flux based on other available datasets containing filtration velocity and set-up is proposed and verified. The analysis of the datasets serves to discuss different filtration mechanisms depending on structure submergence. The approach for separately evaluating the different flux terms is then globally checked for zero freeboard and emerged structures through experimental mass balance. For deeply submerged structures, for which this approach fails, numerical simulations are carried out and the accuracy of the commercial 2DH model MIKE 21 is tested in predicting parameters relevant to the design process as set-up, overtopping and returning flows. Simulations are also presented for a sample emerged case in order to show how some limitations in the tool can be surpassed to allow general applications. The numerical model furthermore invites a description of the physical processes over the whole area of interest, where extensive measurements cannot be performed due to the test imperfect repeatability in presence of irregular waves and thus the impossibility of moving the limited number of available instruments.

Measuring Quality of Life: a Review

Measuring health-related Quality of Life (HRQOL) is becoming increasingly sophisticated as the number of available instruments and potential applications increases. Global, generic and disease-specific HRQOL instruments may be used alone or in combination and each type has advantages and disadvantages. As with any set of observations, the results of HRQOL assessment must be carefully interpreted with the knowledge and consideration of the setting as well as the potential effects of extraneous factors. Application of HRQOL is not meant to stand on its own or to replace other parameters of disease outcome but to complement what is available in the hope of generally improving medical care.

Notes on pareto improvement in incomplete financial markets

these notes describe some recent developments in the analysis of the possibilities for Pareto improvement when, in a competitive environment, financial markets are incomplete. The basic framework is a general methodology for investigating the welfare effects of policy or institutional changes in equilibrium models, when these can be characterized in terms of perturbing the solutions to a system, of smooth equations. Two particular scenarios are discussed in detail: First, the situation where a central government can intervene in the form of wealth taxes and subsidies, and second, the situation where the financial institutions can be modified by increasing the number of available instruments.