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At least 649 records · Page 36Linked to original sources
PubMed2003

Influence of operator experience on canal preparation time when using the rotary Ni-Ti ProFile system in simulated curved canals.

AIM: The aim of this study was to determine the influence of operator experience on the time needed for canal preparation when using a rotary nickel-titanium (Ni-Ti) system. METHOD: A total of 100 simulated curved canals in resin blocks were used. Four operators prepared a total of 25 canals each. The operators included practitioners with prior experience of the preparation technique, and practitioners with no experience. The working length for each instrument was precisely predetermined. All canals were instrumented with rotary Ni-Ti ProFile Variable Taper Series 29 engine-driven instruments using a high-torque handpiece (Maillefer, Ballaigues, Switzerland). The time taken to prepare each canal was recorded. Significant differences between the operators were analysed using the Student's t-test and the Kruskall-Wallis and Dunn nonparametric tests. RESULTS: Comparison of canal preparation times demonstrated a statistically significant difference between the four operators (P < 0.001). In the inexperienced group, a significant linear regression between canal number and preparation time occurred. CONCLUSION: Time required for canal preparation was inversely related to operator experience.

Analysis of Variance↗
PubMed2005

Creatinine measurement: state of the art in accuracy and interlaboratory harmonization.

CONTEXT: The National Kidney Disease Education Program recommends calculating glomerular filtration rate from serum creatinine concentration. Accurate creatinine measurements are necessary for this calculation. OBJECTIVE: To evaluate the state of the art in measuring serum creatinine, as well as the ability of a proficiency testing program to measure bias for individual laboratories and method peer groups. DESIGN: A fresh-frozen, off-the-clot pooled serum specimen plus 4 conventional specimens were sent to participants in the College of American Pathologists Chemistry Survey for assay of creatinine. Creatinine concentrations were assigned by isotope dilution mass spectrometry reference measurement procedures. PARTICIPANTS: Clinical laboratories with an acceptable result for all 5 survey specimens (n = 5624). RESULTS: The fresh frozen serum (FFS) specimen had a creatinine concentration of 0.902 mg/dL (79.7 micromol/L). Mean bias for 50 instrument-method peer groups varied from -0.06 to 0.31 mg/dL (-5.3 to 27.4 micromol/L), with 30 (60%) of 50 peer groups having significant bias (P < .001). The bias variability was related to instrument manufacturer (P < or = .001) rather than method type (P = .02) with 24 (63%) of 38 alkaline picric acid methods and with 6 (50%) of 12 enzymatic methods having significant biases. Two conventional specimens had creatinine concentrations of 0.795 and 2.205 mg/dL (70.3 and 194.9 micromol/L) and had apparent survey biases significantly different (P < .001) from that of the FFS specimen for 34 (68%) and 35 (70%) of 50 peer groups, respectively. CONCLUSIONS: Thirty of 50 peer groups had significant bias for creatinine. Bias was primarily associated with instrument manufacturer, not with type of method used. Proficiency testing using a commutable specimen measured participant bias versus a reference measurement procedure and provided trueness surveillance of instrument-method peer groups.

Bacteriological Techniques↗
PubMedDate not supplied

Addiction as a function of action system properties.

Generalising from some previous analyses of addiction and introducing the concept of an action system which governs all actions which are focused on what Brown (1988) calls "hedonic management," we argue that addictions of every kind involve an action system that displays high salience, low variety, and low vicariance. Addictions also involve what Apter (1982) calls the "paratelic state." A study was carried out comparing 31 drug addicts with 29 control subjects in terms of action system variables. To measure these variables, we constructed a new instrument, the Activity-System Drawing Test, and also used the Telic Dominance Scale to measure frequency of paratelic states. Dysphoria was measured by means of the BATE (anxiety), IDA-13 (depression), SEI (self-esteem), and TAS-20 (alexithymia) instruments. Strong significant differences were found between groups for both action system variables and dysphoria. This supports the idea that addictions emerge from systemic properties of the action system.

Adult↗
PubMedDate not supplied

[Addictions and action systems].

Generalizing from some previous analyses of addiction, and introducing the concept of an action system which governs all actions which are focussed on what Brown (1988) calls "hedonic management", we argue that addictions of every kind involve an action system that displays high salience, low variety and low vicariance. Addictions also involve what Apter (1982) calls the "paratelic state". A study was carried out comparing 31 drug addicts with 29 control subjects in terms of action system variables. To measure these variables, we constructed a new instrument, the Activity-System Drawing Test, and also used the Telic Dominance Scale to measure frequency of paratelic states. Dysphoria was measured by means of the BATE (anxiety), IDA-13 (depression), SEI (self-esteem), and TAS-20 (alexithymia) instruments. Strongly significant differences were found between groups for both action system variables and dysphoria, and there were also strong correlations between both groups of variables. This supports the idea that addictions emerge from systemic properties of the action system.

Adaptation, Psychological↗
PubMed2006

Instrumental stability requirements for exoplanet detection with a nulling interferometer: variability noise as a central issue.

We revisit the nulling interferometer performances that are needed for direct detection and the spectroscopic analysis of exoplanets, e.g., with the DARWIN [European Space Agency-SCI 12 (2000)] or TPF-I [JPL Publ. 05-5, (2005)] missions. Two types of requirement are found, one concerning the mean value of the instrumental nulling function (nl(lambda)) and another regarding its stability. The stress is usually put on the former. It is stringent at short wavelengths but somewhat relaxed at longer wavelengths. The latter, which we call the variability noise condition, does not usually receive enough attention. It is required regardless of telescope size and stellar distance. The results from three nulling experiments performed in laboratories around the world are reported and compared with the requirements. All three exhibit 1/f noise that is incompatible with the performances required by the mission. As pointed out by Lay [Appl. Opt. 43, 6100-6123 (2004)], this stability problem is not fully solved by modulation techniques. Adequate solutions must be found that are likely to include servo systems using the stellar signal itself as a reference and internal metrology with high stability.

Journal Article↗
PubMed2002

Evaluation of a four year experience with a fully instrumented anaerobic digestion process.

For several years, a 1 m3 fixed bed anaerobic digestion process has been operated for the treatment of distillery vinasses. This reactor has been fully instrumented with the following variables available on-line: pH, temperature, liquid and gas flow rates, gas composition (i.e., CH4, CO2 and H2), concentration of bicarbonate, chemical oxygen demand, total organic carbon, volatile fatty acids and partial and total alkalinity, these last four variables being measured twice by different techniques (i.e., using a TOC analyzer, a titrimetric sensor and an infrared spectrometer). The purpose of this paper is to compare the respective benefits of advanced instrumentation for the monitoring of wastewater treatment processes in general, and for anaerobic digestion in particular. It will also provide some statistical analysis of the time required to operate a fully instrumented wastewater treatment process. It is indeed well admitted in the literature that instrumentation is usually the main limitation step for using closed-loop control. However, it is our opinion that, in the near future, this situation will change. This point is discussed based on our four years practical experience.

Anaerobiosis↗
PubMed2000

Training software for high-performance liquid chromatography.

A computer simulation program of reversed-phase high-performance liquid chromatography was developed for training purposes. Experimental retention values of 75 organic compounds on a reversed-phase column at four different percentages of organic modifiers were reduced to a two-parameter retention model with the modifier content as variable. Modifiers used were acetonitrile, methanol and tetrahydrofuran. Isocratic and programmed solvent composition were included together with the usual experimental parameters available in modern HPLC equipment, such as UV diode array and refractive index detection. Instrument specifications were made variable within wide ranges. Detailed dispersion data were made available as tabulated output.

Chromatography, High Pressure Liquid↗
PubMed2000

Comparison between the GHQ-28 and SF-36 (MH 1-5) for the assessment of the mental health in patients with ischaemic heart disease.

OBJECTIVE: To assess the mental health of patients admitted to hospital with suspected ischaemic heart disease, by means of two instruments, the General Health Questionnaire (GHQ-28) and the MH (1-5) dimension of the SF-36 Health Survey Questionnaire, and to compare the psychometric properties of both questionnaires in this population. METHODS: A study was conducted of 185 patients consecutively admitted to hospital with suspected ischaemic heart disease, classified into four groups: Acute Myocardial Infarctus (AMI), unstable angina, non-ischaemic cardiologies, and non-cardiological conditions. Their mental health was assessed by means of the GHQ-28 and the MH 1-5 sub-scales of the SF-36; the validity of the results were analysed by the association of each instrument with socio-demographic (age, sex, social class, and educational level) and clinical (co-morbidity, risk factors, diagnostic groups and background to the illness) variables. The correlation of each instrument with other sub-scales of the SF-36 was studied. The internal consistency was measured by Cronbach's alpha, together with the item-internal consistency and item-discriminant validity. RESULTS: Of the population studied, 71.9% were males and the mean age was 60.2 years (SD: 10.4). The diagnosis for 33.5% was AMI and for 37.8% unstable angina. For all the variables studied, the scores in the two instruments were ordered in the same way, and were significantly worse for females and for the most disadvantaged social class. None of the scales discriminated in respect of the diagnostic group or the presence of comorbidity. However, a linear relationship was observed with risk factors. Cronbach's alpha was 0.95 for the GHQ-28 and 0.80 for the MH 1-5. Correlations with the other dimensions showed ranges of -0.35 to -0.61 for the GHQ-28 and of 0.26 to 0.61 for the MH 1-5. These were highest for the Vitality and Social Functioning sub-scales in both instruments. CONCLUSIONS: The subjective perception of mental health is measured in a similar way by both the MH 1-5 scale of the SF-36 and the GHQ-28. However, since the MH 1-5 questionnaire is shorter, it should be administratively easier to introduce into routine cardiological practice.

Adult↗
PubMed1990

A comparison of the preoperative concerns of open heart surgery patients and their significant others.

This article reports the findings of research about the concerns of open heart surgery (OHS) patients and their significant others (SOs) during the preoperative in-hospital waiting period. Concepts from the Roy Adaptation Model for Nursing framed this study and provided a basis for recognizing the problem, constructing instruments to measure the variable, analyzing and interpreting the data, and drawing implications from the findings. A convenience sample of 21 pairs of OHS and SO subjects reported data while awaiting surgery about demographic characteristics and concerns on self-administered instruments constructed for this research. A multitude of concerns was reported by the subjects, with some similarities and some differences between the OHS patients and their SOs. Implications for practice and theory are drawn, and suggestions for research are made.

Adaptation, Psychological↗
PubMedDate not supplied

Anger in early adolescent boys and girls with health manifestations.

BACKGROUND: Some theorists suggest that boys and girls might experience and express anger in different ways, while others do not, making the study of sex differences in anger an important area for investigation. Further, much has been written theoretically about the health implications of anger, but there is a paucity of studies that have examined the relationship between anger and health variables in early adolescent boys and girls separately. OBJECTIVES: The objectives of this study were to examine sex differences in anger in early adolescents, and to examine the relationship between anger and several health variables, e.g., current health status, clinical health, eudaimonistic health for boys and girls separately. METHODS: This study compared differences in five anger variables between boys and girls, and examined relationships between the anger variables and health variables for boys and girls separately. The final sample consisted of 148 seventh and eighth graders, ages 12 to 14; 81 were girls and 67 were boys. They responded to the State-Trait Anger Expression Inventory and instruments measuring three health variables. RESULTS: Using multisample analysis via LISREL 7 and independent t tests, findings indicated that boys and girls did not differ in the experience and expression of anger. Pearson correlations were used to examine the relationships between the anger variables and the health variables for boys and girls separately. Of the 30 relationships examined, 12 were statistically significant; seven of these correlations were for girls, while five were for boys. CONCLUSIONS: Early adolescent boys and girls may not differ in any meaningful way in self-reported experiences and expressions of anger, but they may differ in health outcomes in relation to various types of anger.

Adolescent↗
PubMed1983

[Methods of psychometric evaluation in geriatrics. Choice of an instrument and its reliability criteria].

As evaluation of patients functioning has become the key-stone of geriatric practice, the appropriated choice of a measuring instrument is of great importance. This article reviews rules and guidelines for a general approach to the orientation of this choice as well as the criteria of reliability of the chosen instrument. Starting from the principle that there is no universal instrument, but only instruments which are more or less adapted to the various requirements, the general characteristics which determine this choice are examined and discussed one by one. They concern the purpose, the study population, the rater, the applications and the variables, the type of instrument and the validation works. The various forms of validity, reliability and sensitivity are listed and defined. These criteria of reliability apply essentially to psychometric instruments with quantitative criteria of measurement, but not to clinical tests which have a qualitative evaluation and which are widely used in neurology. In geriatrics, particular attention should be paid to instruments with a high and demonstrated "face validity".

Aged↗
PubMedDate not supplied

Self-efficacy expectation, behavior performance, and mood status in early recovery from percutaneous transluminal coronary angioplasty.

OBJECTIVE: To describe levels of self-efficacy expectation and performance of selected cardiac recovery behaviors and mood state in patients recovering from percutaneous transluminal coronary angioplasty (PTCA) and to describe the nature of the relationships among these variables. DESIGN: Descriptive, correlational. SETTING: Hospital (postprocedure, predischarge) and home (2 weeks postdischarge). MEASURES: Jenkins Self-Efficacy Expectation Scales and Activity Checklists for Walking Various Distances, Following a Dietary Restriction, Maintaining Health, Resuming Roles and Working; and the Profile of Mood States (POMS) Inventory (McNair, Lorr, and Doppleman). PATIENTS: Adult patients (N = 90; 79% men; mean age = 61 years; 50% working preprocedure) who had undergone a PTCA (first procedure 71.1% and elective procedure 77.8%). Mean hospital stay was 3.9 days. RESULTS: Mean self-efficacy expectation scores were moderately high postprocedure for all behaviors and all, except scores for role resumption, increased significantly (p < 0.01) by 2 weeks postdischarge. Self-efficacy expectation scores were significantly and positively related to behavior performance for all study behaviors except work at 2 weeks, with r values ranging from 0.26 to 0.85. Mean total mood state (POMS) scores improved significantly (p < 0.01) over the 2-week period. Those with higher efficacy expectation scores tended to have higher behavior performance scores and lower levels of mood disturbance. It was noted that the level of mood disturbance was low at both data collection points. CONCLUSIONS: These findings demonstrate the predictive ability of self-efficacy expectation related to behavior performance and describe the relationships of these variables with total mood state as measured by the POMS. Clinical implications drawn from these findings support the individualization of patient teaching needed for this population and point to the need for further research, including development of more clinically useful instruments for assessing these variables.

Activities of Daily Living↗
PubMed1985

Quality of life as a cancer nursing outcome variable.

A reliable and valid multidimensional instrument for measuring quality of life in cancer patients has been developed. Furthermore, a model has been offered that describes how quality of life works as an outcome variable. Using this model, predictions were made of how nursing interventions may directly or indirectly impact on quality of life. Initial testing of the model using data from 135 colostomy patients showed how satisfaction with nursing care and personal control act as cognitive mediators of self-worth, which then impacts on dimensions of quality of life.

Body Image↗
PubMed2006

Estimation of Staphylococcus aureus growth parameters from turbidity data: characterization of strain variation and comparison of methods.

Turbidity methods offer possibilities for generating data required for addressing microorganism variability in risk modeling given that the results of these methods correspond to those of viable count methods. The objectives of this study were to identify the best approach for determining growth parameters based on turbidity data and use of a Bioscreen instrument and to characterize variability in growth parameters of 34 Staphylococcus aureus strains of different biotypes isolated from broiler carcasses. Growth parameters were estimated by fitting primary growth models to turbidity growth curves or to detection times of serially diluted cultures either directly or by using an analysis of variance (ANOVA) approach. The maximum specific growth rates in chicken broth at 17 degrees C estimated by time to detection methods were in good agreement with viable count estimates, whereas growth models (exponential and Richards) underestimated growth rates. Time to detection methods were selected for strain characterization. The variation of growth parameters among strains was best described by either the logistic or lognormal distribution, but definitive conclusions require a larger data set. The distribution of the physiological state parameter ranged from 0.01 to 0.92 and was not significantly different from a normal distribution. Strain variability was important, and the coefficient of variation of growth parameters was up to six times larger among strains than within strains. It is suggested to apply a time to detection (ANOVA) approach using turbidity measurements for convenient and accurate estimation of growth parameters. The results emphasize the need to consider implications of strain variability for predictive modeling and risk assessment.

Animals↗
PubMed2004

Do general and multiple sclerosis-specific quality of life instruments differ?

BACKGROUND: Quality of life instruments provide information that traditional outcome measures used in studies of multiple sclerosis do not. It is unclear if longer, disease-specific instruments provide more useful information than shorter, more general instruments, or whether patients prefer one type to another. METHODS: We conducted a cross-sectional study of quality of life in a multiple sclerosis clinic population using a mailed questionnaire that combined three different quality of life instruments; the SF-36, the Multiple Sclerosis Quality of Life Instrument-54, and the EuroQol EQ-5D. We assessed the feasability of using each instrument and patient preference for each, calculated correlation coefficients for the summary scores of each instrument and other measures of disease severity, and calculated odds ratios from proportional odds models comparing each instrument with the Expanded Disability Status Scale. RESULTS: We did not find substantial differences between the three instruments. All were well-received by patients, and over 75% felt that the combination of the three instruments best assessed their quality of life. For each instrument there was substantial variability between patients with similar quality of life scores in terms of their disability (as assessed by the Expanded Disability Status Scale and their own perception of their disease severity and quality of life (on simple 1-10 scales). CONCLUSIONS: Quality of life instruments are easy to use and well-received by patients, regardless of their length. There do not appear to be clinically important differences between general and disease-specific instruments. Each instrument appears to measure something other than a patient's disability or perception of their own disease severity or quality of life.

Adult↗
PubMed2000

Assessing the impact of differential measurement error on estimates of fine particle mortality.

In air pollution epidemiology, error in measurements of correlated pollutants has been advanced as a reason to distrust regressions that find statistically significant weak associations. Much of the related debate in the literature and elsewhere has been qualitative. To promote quantitative evaluation of such errors, this paper develops an air pollution time-series model based on correlations among unit-normal variables. Assuming there are no other sources of bias present, the model shows the expected amount of relative bias in the regression coefficients of a bivariate regression of coarse and fine particulate matter measurements on daily mortality. The model only requires information on instrumental error and spatial variability, along with the observed regression coefficients and information on the true fine-course correlation. Analytical results show that if one pollutant is truly more harmful than the other, then it must be measured more precisely than the other in order not to bias the ratio of the fine and course regression coefficients. Utilizing published data, a case study of the Harvard Six-Cities study illustrates use of the model and emphasizes the need for data on spatial variability across the study area. Current epidemiology time-series regressions can use this model to address the general concern of correlated pollutants with differing measurement errors.

Air Pollutants↗
PubMed1998

Reproducibility of topographic measures of the glaucomatous optic nerve head.

AIMS/BACKGROUND: Laser scanning tomography provides an assessment of three dimensional optic disc topography. For the clinical purpose of follow up of glaucoma patients, the repeatability of the various measured variables is essential. In the present study, the reproducibility of morphometric variables calculated by the topographic scanning system, TopSS (Laser Diagnostic Technology, San Diego, CA) was investigated. METHODS: Two independent measurements (30 minutes apart) each consisting of three complete images of the optic disc were performed on 16 eyes of 16 glaucoma patients using a TopSS. The instrument calculates 14 morphometric variables for the characterisation of the optic disc. RESULTS: From the two tailed paired tests, all variables were seen to have good reproducibility. However, correlation and regression analyses showed that only the three variables, volume below, half depth area, and average cup depth, are acceptably reproducible. CONCLUSION: The TopSS provides three variables which describe the physiological shape of the optic disc that have high reproducibility. These three variables might be useful for following the progression of optic disc changes in glaucoma patients.

Aged↗
PubMedDate not supplied

Life stress and risk of precancerous cervical lesions: a pretest directed by the life stress model.

PURPOSE/OBJECTIVES: To present the results of a pilot study to pretest instruments designed to measure selected variables named in the Life Stress Model, a model of health outcomes. Additional aims were to determine the effect of completing personal risk assessments for precancerous squamous-cell intraepithelial lesions of the cervic (SIL) on receptivity to cervical cancer prevention information and to extend knowledge of stressful life events experienced by inner-city women attending high-risk health clinics. DESIGN: Cross-sectional. SAMPLE: 20 adult women attending high-risk prenatal or human immunodeficiency virus (HIV) outpatient clinics in one of two New York City hospitals. Most were recovering drugs abusers; half were diagnosed with HIV infections. METHODS: Data were collected by self-report using standard measures. Demographics, medical histories of immunosuppressive states, and investigator-developed screening inventories of behavioral and dietary risk factors associated with SIL also were administered. MAIN RESEARCH VARIABLES: Life event stressors, psychological state, social support, symptom distress, and SIL diagnosis. FINDINGS: Instruments met acceptable psychometric standards for internal consistency, but the standard measure of stressful life events did not capture the full range of stressors experienced by this group of patients: hovering relatives, abusive spouses, HIV diagnosis, changes in welfare benefits, the HIV status of the unborn, and mandatory foster care. Although unable to recall cancer histories of family members, about half of the women who completed study instruments were interested in receiving more information cervical cancer. Exploratory analyses suggest that women diagnosed with SIL experience more psychological distress and family disfunction than women without SIL. CONCLUSIONS: Completing personal SIL risk assessments may stimulate patients' receptivity to cancer risk factor information. Health outcomes studies guided by the Life Stress Model may prove fruitful. IMPLICATIONS FOR NURSING PRACTICE: Cancer risk factor assessments may be an important method for promoting receptivity to cancer prevention information.

Adult↗