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At least 757 records · Page 42Linked to original sources
PubMed1998

Influence of acquisition parameters on hemodynamic measurements with the Heidelberg Retina Flowmeter at the optic disc.

PURPOSE: The Heidelberg Retina Flowmeter (HRF; Heidelberg Engineering GmbH, Heidelberg, Germany) is a new instrument that determines hemodynamic variables at discrete locations of the retina and the optic disc. The objective of this study was to evaluate the influence of various HRF recording settings on the long-term variability of the HRF parameter. "Flow," computed at the optic nerve head in healthy individuals. METHODS: The authors obtained 2 sets of 5 HRF recordings in 10 healthy individuals (age range, 23-60 years). The HRF recordings were obtained within a scan area of 10 degrees x 2.5 degrees (set 1) and 20 degrees x 5 degrees (set 2). For each set, the HRF recordings were obtained on 5 consecutive days. Respective HRF recordings for both sets were obtained on the same days. On these recordings, the HRF parameter, "Flow," was computed at 3 different regions of interest (temporal superior, temporal inferior, and temporal rim of the optic disc). At all three locations, Flow was computed within windows of measurement of 10 pixels x 10 pixels and 20 pixels x 20 pixels. The effect of larger windows (30 pixels x 30 pixels, 40 pixels x 40 pixels, and 50 pixels x 50 pixels) was tested at the temporal rim of the optic disc. RESULTS: The highest reliability coefficient was reached with a scan area of 20 degrees x 5 degrees at the temporal superior rim of the optic disc (r = 0.93). Within a scan area of 20 degrees x 5 degrees, the size of the user-defined measuring window did not influence the reliability. Two models of analysis of variance disclosed that the only effect on the computed value of Flow that reached statistical significance was that because of the scan area (F = 11.172; p = 0.001). The location of the window of measurement and its size had no statistically significant effect. CONCLUSION: The present results show that the location of the window of measurement has an important effect on the long-term variability of the HRF parameter, Flow. In addition, different scan areas influence significantly the computed values of this parameter.

Adult↗
PubMed1994

Variability of sonic scaling tip movement.

The sonic scaler operates at frequencies of 2 to 6 kHz and is powered by pressurised air from the dental unit. Variables likely to affect how these instruments perform include the air pressure input and load applied by the operator. Other variables include the brand of scaler used and the clinical technique of the operator. The aim of this study was to investigate differences in instrument performance within a dental teaching hospital. Light microscopy was used to measure the displacement amplitudes in air of 32 Sonic scalers which were in regular clinical use in three departments (Periodontal Unit, Restorative Unit and School of Hygiene). During operation, the air pressure was kept at a constant 2.8 kg cm-2 and measurements were made on each instrument with three scaling tips (universal, sickle and periodontal). The periodontal scaling tip exhibited the greatest vibration although this was not significant (p > 0.1). There was a significant difference in performance between the different clinical environments where the scalers were used (p < 0.01). 4 new sonic scaling instruments made by different manufacturers were selected for displacement amplitude measurements. One brand of sonic scaler demonstrated a significantly greater displacement amplitude in comparative measurements between instruments (p < 0.01). This study demonstrated differences in the oscillation of sonic scalers which should be recognised by clinicians when using these instruments, since they may influence clinical performance.

Calibration↗
PubMed1996

MMPI-Rorschach interrelationships: proposed criteria for evaluating explanatory models.

An extensive empirical literature, spanning 50 years and 45 published investigations, leads to the conclusion that the Rorschach and the Minnesota Multiphasic Personality Inventory (MMPI) bear little or no meaningful relationship to each other. An inherent tension exists between these empirical findings and the widespread clinical practice of integrating MMPI and Rorschach results. At least three perspectives have been advanced concerning the relationship between these two instruments. One view holds that variables from the two measures will demonstrate significant patterns of convergence only in carefully designed research studies that involve specific, well-constructed and theoretically derived predictions. A second view postulates that although variables from the Rorschach and MMPI do not bear a high intercorrelation with each other, these variables may be combined to contribute significantly to the prediction of outcome variance. In this view, the combined use of the two instruments yields clinically useful increases in incremental validity not achievable by the use of either instrument in isolation. A third approach is reflected in the proposition that although the MMPI and Rorschach do not produce significant interrelationships under general conditions, meaningful relationships may be yielded under specific psychometric conditions, for example, under conditions in which the response styles are consistently displayed across those two instruments. This article will review research evidence related to each of these perspectives, with particular emphasis on the importance of clearly specifying the criteria to be applied in evaluating these models. The concepts of parsimony and heuristic value are proposed for these evaluation purposes.

Journal Article↗
PubMed2002

Measuring health beliefs in Spanish-speaking Mexican Americans with type 2 diabetes: adapting an existing instrument.

Mexican Americans bear a disproportionate burden of type 2 diabetes, and although clinicians and researchers are beginning to develop culturally competent interventions, few instruments are available for measuring variables relevant to health outcomes. The purpose of this study was to determine the psychometric properties of a diabetes-related health belief instrument translated for use with Spanish-speaking Mexican Americans. Three hundred and twenty-six Spanish-speaking Mexican Americans from Starr County, a Texas-Mexico border community, diagnosed with type 2 diabetes participated in the study. Factor analysis was used to examine the factor structure of the instrument, and reliability testing was conducted to determine the internal consistency of the resulting factors. The final instrument had 25 items with four subscales-Barriers, Social Support for Diet, Impact of Job on Therapy, and Benefits of Therapy-and one item to measure, Control. Internal consistency coefficients for these subscales were .56, .62, .86, and .90, respectively. The translated instrument needs to be tested over time with other Hispanic populations.

Analysis of Variance↗
PubMedDate not supplied

A review of research instruments for use during the postpartum period.

Locating existing instruments available to measure key variables is critical to the success of a research study. However, this process can be a time-consuming activity. In this article, selected instruments available for use in research during the postpartum period are reviewed. These instruments are divided into two categories. The first category deals with instruments that focus on mothers only. These questionnaires measure mothers' perceptions of their deliveries, their adaptation to motherhood, and their breastfeeding experiences. The second category centers on instruments that both parents can complete. These instruments measure parents' perceptions of their parenting role, sense of competence, problem-solving ability, and perceptions of their newborns. The psychometric properties of each instrument are described, and selected nursing research studies that used the instrument are reviewed.

Breast Feeding↗
PubMed1990

Reduced behavioral variability in extinction: effects of chronic treatment with the benzodiazepine, diazepam or with ethanol.

Extinction of a food reinforced habit results in an increase in the variability of the response learned in acquisition and in the appearance of previously suppressed competing responses. The purpose of the present study was to examine the effects of chronically administered diazepam (0.0, 1.5, 3.0, or 6.0 mg/kg, IP, -30 min) or 10% ethanol (0.0, 1.0, 1.5, or 2.0 g/kg, IP, -15 min) on such behavioral variability in the extinction of radial maze performance. Eight groups of food deprived rats (n = 6) were given one of the forementioned doses for 2 sessions of baseline, 18 sessions of acquisition, and 5 sessions of extinction. In acquisition, eight rewards of two food pellets were obtained on each of three trials in each session. The food well at the end of each arm was rebaited when emptied by the animal, consequently an entry into any arm was reinforced. In baseline and extinction no food was available in the maze. Each session consisted of three 10-min trials. In extinction, compared to treatment with vehicle, both diazepam and ethanol treatments decreased the rate of the instrumental response, arm entry, and increased the variability of the instrumental response and of competing responses. Only the effects of the drugs on the competing responses in extinction were greater than those observed in acquisition. It was concluded that the interference-reduction model of drug action best described the magnitude of the drug effects and the variability-reduction model best predicted the direction of the effects.

Animals↗
PubMed2002

[Complex of factors affecting heart rate dispersion in survivors of myocardial infarction].

AIM: To establish complex of independent variables related to parameters of heart rate variability in patients with postinfarction cardiosclerosis. MATERIAL: Seventy four patients (age 49-/+0.8 years) were studied in 6 months or later after myocardial infarction. Temporal and spectral characteristics of heart rate variability from 5 min ECG strips were sequentially included in a multiple linear regression model as dependent variables while data of clinical and instrumental investigation were considered as independent parameters. RESULTS AND CONCLUSION: Depression of heart rate variability in survivors of myocardial infarction was linked to age, late postinfarction remodeling of the heart, development of systolic and diastolic left ventricular dysfunction and clinical severity of heart failure.

Factor Analysis, Statistical↗
PubMed1978

External quality-control survey of cholesterol analyses performed by 12 lipid research clinics.

We report accuracy and precision achieved in the automated analysis for cholesterol in a long-term multilaboratory study, presenting and evaluating the significance of data accumulated by 12 Lipid Research Clinics (LRC's) in the analysis of 18 unknown surveillance pools during three years. The average bias for all pools and for 13 autoAnalyzer II (Technicon Instruments Corp., Tarrytown, N.Y. 10591) instruments in the 12 clinics was -0.41% (range -1.2 to +0.3%), as compared to values established by reference methodology. The regression equation relating observed cholesterol values (y) to reference values (x) was: y = 0.35 + 0.977x. The bias varied from pool to pool (-2.3 to +5.3%), positive biases being observed for pools with cholesterol concentrations less than 1.4 g/liter, and negative biases for those pools with higher concentrations. Total standard deviations ranged between 25 and 75 mg/liter, and total CV's for most individual instruments were between 1 and 3%. Of the variability for a particular pool, less than 20% was due to differences among instruments, and within- and between-run variabilities were approximately equal. These trends were the same as those previously observed [Clin. Chem. 23, 1744 (1977)] in the analysis of bench control pools of known cholesterol concentration.

Autoanalysis↗
PubMed1982

A scale for measurement of the problem patient labeling process.

Physicians frequently use the term problem patient to subjectively label individuals who present with vague and shifting symptoms involving multiple organ systems, chronically complain, constantly worry about their health, and contribute in other ways to physician uncertainty and frustration. This article describes the development and reliability and validity studies of an instrument that objectively measures physicians' perceptions of problem patients. As such, the instrument quantifies a key qualitative impression that physicians may formulate. Use of the instrument in an ambulatory care setting yielded highly reliable data which, when subjected to correlation and regression analyses, display expected relationships with a parsimonious set of independent variables. We conclude that the instrument holds promise for further clinical and research work involving problem patients.

Ambulatory Care↗
PubMed2006

Casting light on the concept of patient satisfaction by studying the construct validity and the sensitivity of a questionnaire.

PURPOSE: This study aims to explore the construct validity and the sensitivity of a patient satisfaction questionnaire for the purpose of gaining a better understanding of the concept, and of issues surrounding its measurements. DESIGN/METHODOLOGY/APPROACH: Several statistical analyses were used to study the reliability, construct validity, and the sensitivity of a patient satisfaction questionnaire. FINDINGS: The study supported the construct validity, high internal consistency, and homogeneity of the instrument. Two factors were found; one consisted of negatively worded items and the other of positively worded items. The negatively worded items contributed more than the positively worded items to the sensitivity of the instrument. Items were identified that contribute little or nothing to the construct validity and/or the sensitivity of the questionnaire. RESEARCH LIMITATIONS/IMPLICATIONS: The effect of wording on the variability and sensitivity of the instrument can be explained both as a consequence of response set bias and with regard to the theories against which two phenomena were being measured - patient satisfaction and patient dissatisfaction. The development of two kinds of instruments is proposed: those that measure patient dissatisfaction and are sensitive to minute changes in nursing care and those that measure both concepts and capture what patients find important in their care. ORIGINALITY/VALUE: The paper demonstrates how an analysis of the construct validity and the sensitivity of patient satisfaction instrument, can enhance understanding of the concept. It contributes to the debate about whether patient satisfaction and dissatisfaction are opposite ends of the same continuum or two different phenomena that require two different definitions.

Data Interpretation, Statistical↗
PubMedDate not supplied

Application of improved standardization methods and instrumentation in the USP particulate test for SVI.

The USP (788) requirement for particulate matter in small volume injections (SVI) became effective January 1, 1986. The standardization component of the requirement is time-consuming and open to subjective interpretation. Current generation light obscuration (LO) counters offer many advantages over those available when (788) was implemented. Significant improvements may be made to the requirement by optimizing the counter standardization procedure and making provisions for use of newer instrumentation. Key improvements to (788) suggested by our experience with the SVI test method include: (1) revision of the requirement to include a time-effective stand-alone standardization procedure; (2) provision for use of currently marketed LO counter systems; (3) development of new standard materials including a count standard; and, (4) deletion of the present requirement for validation of LO counts by microscopy. Significant user advantages accruing to an improved methodology and the use of new instrumentation will include decreased time spent in standardization, lower variability of data between different laboratories, and less instrument down time.

Calibration↗
PubMed1992

Fundamental aspects of pulse phase-locked loop technology-based methods for measurement of ultrasonic velocity.

A new instrument based on a constant frequency pulse phase-locked loop concept has been developed to accurately measure the ultrasonic phase velocity in condensed matter. Measurements of the sound velocity in ultrapure water are reported in which both damped and undamped transducers are used with the instrument together with reflectors of various thicknesses placed in the sound propagation path. An analysis of measurements made with the new instrument and similar measurements, taken under identical experimental conditions, using a popular variable frequency pulsed-phase-locked loop instrument is reported. Uncertainties in both measurement systems are analyzed and discussed. A method for measuring inherent phase shifts, not addressed by previous investigators, within the variable frequency pulsed phase-locked loop system and a derivation of the equations that govern the overall use of variable frequency systems using phase-sensitive comparisons are presented. The effects of a finite pulse length on the measurements of phase velocity in dispersive media are addressed in detail.

Humans↗
PubMed2002

Patient satisfaction with outpatient physical therapy: instrument validation.

BACKGROUND AND PURPOSE: Patient satisfaction with physical therapy is used as an outcome variable. The purpose of this study was to develop and test an instrument used to determine which variables are associated with the satisfaction of patients receiving outpatient physical therapy. SUBJECTS: During the pilot study, 191 patients participated, and 1,868 patients then participated in the main phase of this work. METHODS: Using a survey instrument developed by the authors, subjects responded to global questions concerning overall satisfaction with physical therapy. Content validation of the instrument was investigated using item correlation, principal components analysis, and factor analysis. Reliability was measured using the standard error of measurement. Concurrent validity was investigated by correlating summary scores of the final survey instrument with global measures of satisfaction. RESULTS: Reliability was best for a 10-item questionnaire. Patient satisfaction was most associated with items that reflected a high-quality interaction with the therapist (eg, time, adequate explanations and instructions to patients). Environmental factors such as clinic location, parking, time spent waiting for the therapist, and type of equipment used were not strongly correlated with overall satisfaction with care. DISCUSSION AND CONCLUSION: Because the time the therapist spent with patients and the behavior of the therapists are important for patient satisfaction, emphasis on cost-cutting, high patient volume, and the use of "care extenders" may jeopardize satisfaction.

Female↗
PubMed2002

Homesickness among students in two cultures: antecedents and consequences.

Review of the theoretical and empirical literature on homesickness showed that despite recent advances, scientific understanding of the impact on students of leaving home for college is still limited. Further empirical investigation using standardized measures, structural equation models and including additional mediating/moderating variables is needed. Two studies were thus conducted, one in the Netherlands, and one in the UK. Homesickness was investigated among recent-intake students, using a newly developed instrument, the Utrecht Homesickness Scale. Variables investigated in relationship to homesickness included depression, personality factors (self-liking, competence, self-esteem) and family situation (attachment to family). Homesickness was found to be a common though differentially prevalent phenomenon (approximately 50% in the Netherlands; 80% in the UK). Structural equation models showed that students missed family and friends and had difficulties adjusting to college life. These difficulties were associated with ruminations about home and loneliness, which themselves were associated with depression. There were differences in intensity (UK students were more homesick) and there were gender differences (UK females experienced more homesickness). Both the personality and family situation factors had an impact on homesickness. The results supported the conceptualization of homesickness as a 'mini-grief', to be viewed from theoretical perspectives in the field of loss and bereavement.

Adult↗
PubMedDate not supplied

Relationships between objective assessment of ligament stability and subjective assessment of symptoms and function after anterior cruciate ligament reconstruction.

BACKGROUND: Relationships between objective assessment of ligament stability and subjective assessment of symptoms and function after anterior cruciate ligament reconstruction have not been established. HYPOTHESIS: Relationships exist between objective and subjective assessments after anterior cruciate ligament reconstruction. STUDY DESIGN: Case series. METHODS: Patients (N = 202) undergoing anterior cruciate ligament reconstruction with 2-year minimum follow-up were studied. Objective variables of ligament stability at follow-up included instrumented laxity, Lachman examination, and pivot-shift examination. Subjective variables of symptoms at follow-up included pain, swelling, giving way, locking, crepitus, stiffness, and limping. Subjective function at follow-up included walking, squatting, stair climbing, running, cutting, jumping, twisting, activity limitation, sports level, activities of daily living level, work level, knee function, sports participation, Lysholm score, and satisfaction with outcome. RESULTS: Instrumented knee laxity and Lachman examination had no significant (P >.05) relationships with any subjective variables of symptoms and function. Pivot-shift examination had significant associations with satisfaction (P =.03), partial giving way (P =.01), full giving way (P =.01), difficulty cutting (P =.01), difficulty twisting (P =.01), activity limitation (P =.01), overall knee function (P =.03), sports participation (P =.02), and Lysholm score (P =.01). CONCLUSIONS: The pivot-shift examination may be a better measure of "functional instability" than instrumented knee laxity or Lachman examination after anterior cruciate ligament reconstruction.

Adolescent↗
PubMedDate not supplied

Comparing measurements of retinal nerve fiber layer thickness obtained on scanning laser polarimetry with fixed and variable corneal compensator.

PURPOSE: To compare retinal nerve fiber layer (RNFL) thickness measurements obtained on scanning laser polarimetry (SLP) with commercially available instruments coupled with fixed (FCC) and variable corneal compensator (VCC). METHODS: Forty-two eyes of 42 patients underwent a complete ophthalmologic evaluation and achromatic automated perimetry (24-2 program, SITA standard strategy). Nineteen eyes were healthy (average mean deviation: -0.12 dB +/- 2.26) and 23 glaucomatous (average mean deviation: -4.92 dB +/- 6.49). All patients underwent SLP with both FCC and VCC. Adequate compensation of corneal birefringence on FCC-SLP was checked acquiring macular retardation map (MRM). RNFL thickness was evaluated considering superior and inferior maximum (SM, IM), average thickness and ellipse average (AT, EA), and superior and inferior average (SA, IA). Mean values (+/-SD) for each parameter measured by the two polarimeters were compared and linear regression calculated. The ability of each parameter to discriminate between normal and glaucomatous eyes was evaluated on both polarimeters calculating area under ROC curve. RESULTS: A significant linear correlation for all parameters was noted (r range: 0.65-0.78). VCC produced slightly higher thickness values than FCC, both in normal and glaucomatous eyes. On both polarimeters, area under ROC curve for all parameters discriminated adequately healthy from glaucomatous eyes (range: 0.68-0.81). CONCLUSIONS: In a highly comparable and selected group of normal and glaucomatous eyes, FCC-SLP and VCC-SLP showed considerable concordance in measuring peripapillary RNFL thickness, both for sectorial and global parameters. Proper corneal birefringence compensation provided separation of normal from glaucomatous eyes on both polarimeters.

Adult↗
PubMed2004

Matching strategies in cognitive research with individuals with high-functioning autism: current practices, instrument biases, and recommendations.

A meta-analysis was performed on the 133 cognitive and behavioral papers in autism using comparison groups in the 1999-2002 period. High-functioning (average IQ: 84.7), adolescents (average, 14.4 years) are largely dominant. IQ is the most frequent matching variable in use (51.2%). The instruments that are most frequently used to determine IQ or general level are Wechsler scales (46.9%), British Picture Vocabulary Scale (BPVS; 22.3%), and Raven Progressive Matrices (RPM; 16.9%). In order to determine if these instruments were equivalent when applied to individuals with pervasive developmental disorders (PDDs), Wechsler IQ, EVIP (a French Canadian translation of the BPVS), and RPM were given to a group of 14 individuals with autism and 12 with Asperger syndrome. Comparison of Wechsler and RPM IQs values, expressed as percentiles, to percentile values of EVIP score revealed that EVIP (and to a lesser extent RPM) considerably overestimates the level of all PDD participants as compared to Wechsler Verbal IQ (VIQ), Performance IQ (PIQ), or Full-Scale IQ (FSIQ), whereas these instruments are reported to be strongly correlated in typically developing individuals. This study reveals that identification of objects from a verbal label--the BPVS-PPVT-EVIP task--is a peak of ability in high functioning individuals with PDDs. This peak of ability, even superior to that of block design, has a detrimental effect on matching based on this instrument. A recommendation to replace BPVS/PPVT/EVIP or RPM by Wechsler scale as a basis of IQ/level matching is provided. Accordingly, the former instruments are a potential source of type-1 (for cognitive deficits) or type-2 (for cognitive hyperfunctioning) errors.

Adolescent↗