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PubMed1987

Instrumental set-up as a factor influencing the variability of retention index values in high pressure liquid chromatography.

The influence of different laboratory set-ups on HPLC retention index values of selected acidic and basic drugs was investigated. The RI values of drugs were calculated using the alkyrarylketone scale. Two columns filled with different batches of the same Hypersil ODS phase were consecutively used in two laboratories under identical conditions, but using different instrumentation. The study showed that the different laboratory set-ups influence the precision of RI values, and the differences in column filling affect the accuracy.

Chromatography, High Pressure Liquid↗
PubMed2006

[Psychometric contributions to the assessment of psychosocial responses in nursing].

This article presents the methodological bases that guide the development of instruments to measure psychosocial variables. It describes the theoretical, empirical or experimental and analytical and exemplifies the theoretical steps through the experience of developing an instrument to measure powerlessness as a nursing diagnosis. The most difficult procedures for developing instruments to are the theoretical steps. They require the development of theoretical sensitivity as a continuous going forward and backward between concrete and abstract issues; they also require the development of tolerance towards ambiguity, but without abandoning the examination of evidences.

Mental Disorders↗
PubMed1992

Accuracy and precision of computer-aided sperm analysis in multicenter studies.

STUDY OBJECTIVES: To develop methods of instrument calibration and standardization that enable the use of computer-aided sperm analysis (CASA) technology in multicenter studies of sperm motility. SETTING: Clinical semen evaluation for the andrology laboratory and in vitro fertilization programs. PATIENTS: Semen specimens were selected from the videotape archives of the University of California at Davis Andrology Laboratory and used to produce a videotape reference standard for CASA instrument testing and calibration. Four identical CASA instruments, two each at two sites, were used to analyze the videotape. Machine accuracy was verified by manual analysis of the videotape. RESULTS: The coefficient of variation (CV) for repeated measures was between 1% and 8% for each variable on all CASA instruments. Mean values for CASA parameters varied as a function of the digitization threshold. A minimum CV was obtained at a particular threshold setting, suggesting an optimum for each machine. Because of high within-machine precision, slight differences in mean values between machines were statistically significant for some variables and some specimens; such differences are probably not biologically significant. CONCLUSION: Multicenter standardization of CASA instrumentation is possible, but threshold settings are one source of variation that must be controlled using CVs or another means of objective calibration. One method is to adjust the threshold of each instrument until the count obtained by CASA equals the count obtained by the manual method used to determine the dilution requirements for neat semen.

Computers↗
PubMed1991

[Some criteria for the planning and evaluation of the ruggedness test of HPLC methods].

Ruggedness is a measure of the reproducibility of the individual test results when the procedure is used repeatedly to determine the same homogeneous sample in a variety of specified experimental conditions. Ruggedness testing can be divided into two major groups: Type-A, when the influence of the changed environmental conditions (different equipment, analysts, etc.) on the analytical performance parameters and results are tested, and Type-B, when the effect of variation in the experimental conditions are checked. In the latter case, Type-B group can be further classified into two major subgroups: ruggedness testing of sample preparation and chromatographic separation. Checking sample preparation for ruggedness testing includes the investigation of various sample preparation procedures, such as: liquid-liquid extraction, solid phase extraction, direct sample introduction and derivative formation. The investigation of column-to-column variability, changes in the instrumental and experimental conditions belongs to the ruggedness testing of chromatographic separation. In this paper the basic principles of selection for experimental variables for various ruggedness tests are discussed introducing a new possibility to design multivariable-multicriteria system, and the evaluation of a single-variable-single-criterion system, as well. In general, from the work introduced in this paper, it can be concluded that when new analytical methods are developed, it is quite important to be aware the sensitivity of the method to variations in the specified conditions. For adequate performance of ruggedness testing: a) the factors (variables) which have significant influence on the chromatographic results can be firstly selected, b) maximum acceptable deviations from the prespecified experimental conditions can be decided, and c) the acceptable deviations from the values of the prespecified analytical performance parameters can be defined.

Chromatography, High Pressure Liquid↗
PubMed2004

The role of increasing temperature variability in European summer heatwaves.

Instrumental observations and reconstructions of global and hemispheric temperature evolution reveal a pronounced warming during the past approximately 150 years. One expression of this warming is the observed increase in the occurrence of heatwaves. Conceptually this increase is understood as a shift of the statistical distribution towards warmer temperatures, while changes in the width of the distribution are often considered small. Here we show that this framework fails to explain the record-breaking central European summer temperatures in 2003, although it is consistent with observations from previous years. We find that an event like that of summer 2003 is statistically extremely unlikely, even when the observed warming is taken into account. We propose that a regime with an increased variability of temperatures (in addition to increases in mean temperature) may be able to account for summer 2003. To test this proposal, we simulate possible future European climate with a regional climate model in a scenario with increased atmospheric greenhouse-gas concentrations, and find that temperature variability increases by up to 100%, with maximum changes in central and eastern Europe.

Journal Article↗
PubMed2004

[Lack of association between blood pressure variability and left ventricular hypertrophy in essential hypertension].

BACKGROUND AND OBJECTIVE: Blood pressure (BP) fluctuations may contribute to the development of target organ damage in essential hypertension. However, a possible relationship with left ventricular hypertrophy (LVH) is controversial. The aim of the present study was to analyze the association between BP variability, defined through different instrument measures, and LVH in a group of essential hypertensive patients. PATIENTS AND METHOD: Forty-three untreated hypertensive patients were studied. BP variability was evaluated by using both non-invasive, beat-to-beat finger 24-hour monitoring (Portapres) and discontinuous oscillometric ambulatory blood pressure monitoring (ABPM). All patients underwent echocardiography in order to detect the presence or absence of LVH. RESULTS: Thirty out of 43 patients studied (70%) exhibited LVH. Office [167.7 (19.5) versus 156.7 (14.9) mmHg; p = 0.032], 24-hour ambulatory [146.6 (15.7) versus 131.9 (15.1) mmHg; p = 0.003] and 24-hour continuous finger [147.5 (21.3) versus 135.7 (14.2) mmHg; p = 0.046] systolic BP were significantly higher in patients with LVH with respect to those without cardiac hypertrophy. No differences were observed in terms of nocturnal BP fall, ABPM 24-h standard deviation of BP or continuous finger BP variability estimates. CONCLUSION: Left ventricular hypertrophy is mainly correlated with the severity of systolic BP elevation, but not with BP variability, neither long-term nor short-term.

Blood Pressure↗
PubMed2001

Outcomes of depression in early adolescents.

The purpose of this study was to examine the relationship between depressed mood and depressive symptomatology and the influence of both variables on perceived social support, interpersonal conflict, general well-being, and perceived health status in 144 early adolescents. The subjects responded to instruments measuring the study variables in classroom settings. Two bivariate regression structural equation models were examined using the LISREL 7 computer software program. In the health model, depressed mood had a direct positive effect on depressive symptoms and a direct negative effect on well-being and on perceived health status. Depressive symptoms had a direct negative effect on well-being and on perceived health status. In the interpersonal model, depressed mood had a direct positive effect on depressive symptoms and on conflict and a direct negative effect on social support. Depressive symptoms had a direct positive effect on conflict and a direct negative effect on social support.

Adolescent↗
PubMed1992

The variability of response of scoliotic spines to segmental spinal instrumentation.

Ninety-two patients (71 idiopathic, 15 neurogenic, 2 Marfan's syndrome, 1 Down's syndrome, 1 osteogenesis imperfecta, 1 Prader-Willi syndrome, 1 Klippel-Trenaunay-Weber syndrome), ages 9-49 years, had posterior spine fusion and stabilization with Luque L-rods and sublaminar segmental wires (SSI) for progressive scoliosis. There were no neurologic complications. The average preoperative major curve of 52 degrees (37-113 degrees) initially corrected to 30 degrees (6-94 degrees), and at last follow-up (range, 2-7 years), was 33 degrees (8-90 degrees). There was marked variability in curvature correction and maintenance of correction, with 14 patients progressively decreasing their curvatures postoperatively. Average preoperative Pedriolle vertebral rotation angle for all 92 patients was 16 degrees (4-26 degrees), which initially corrected to 14 degrees (0-24 degrees), and at last follow-up remained 14 degrees (0-23 degrees). Although SSI had little influence on rotation, 12 patients progressively decreased their rotational deformity after operation. Aside from the positive influence of curve flexibility on the degree of postoperative curve correction, the authors could not identify factors explaining how curvature and vertebral rotation responded so variably to SSI. The authors recommend continued use of SSI to stabilize curvatures in osteopenic patients (particularly those with neuromuscular disease), but rotational deformity will probably persist.

Adolescent↗
PubMedDate not supplied

A model for predicting the counseling practices of physicians.

The authors present a conceptual model of the determinants of the counseling practices of physicians and an empirical test of the model. Seventy-six per cent of a 50% random sample of physicians in a western county medical society completed a questionnaire (n = 151). This instrument measures the aggressiveness, the indications and techniques used by physicians in counseling patients about smoking, exercise, weight control and alcohol use. The independent variables assessed by this instrument are motivations, perceived skills and barriers, medical specialty, and personal health habits. Significant associations were found between the counseling practices reported and physicians' personal health habits, attitudes and specialties. Non-surgeons counseled more patients, counseled more intensively, and used a greater variety of techniques than surgeons and obstetrician-gynecologists. In general, physicians who had poor health habits did not fully counsel patients about those habits; however, physicians attempting to improve poor habits counseled patients significantly more often than physicians who were not trying to change their own behavior. Health maintenance efforts among physicians may have a multiplier effect.

Alcohol Drinking↗
PubMed1976

Field work experience ratings and certification examination scores as predictors of job performance and satisfaction in occupational therapy.

The American Occupational Therapy Association's certification instruments, the Certification Examination for Occupational Therapists Registered and the Field Work Performance Report, were examined in terms of their ability to predict future job performance and satisfaction of occupational therapists. A job satisfaction questionnaire was administered to 208 occupational therapists, and their supervisors rated them on a job performance instrument. The resulting correlations between these work adjustment variables and the previously administered certification instruments failed to reveal any predictive ability. Some plausible reasons for these negative results and possible directions for further research into this professional screening process were explored.

Certification↗
PubMed1993

Establishing the reliability and validity of a new instrument: pilot testing.

Development of instruments to measure psychosocial variables is a complex process that begins with concept analysis and concludes with pilot testing to establish initial reliability and validity properties. Although the instrument development process is lengthy. PACU nurses are encouraged to follow all steps; if they do not, they will be unsure of what is measured or the meaning of the finding. Discussed here is the final phase of the instrument development process; calculating and analyzing construct validity and internal consistency reliability. An example is given that applies reliability and validity methods to a hypothetical instrument.

Factor Analysis, Statistical↗
PubMedDate not supplied

[Statistics and medical decision making].

Statistics is the science that studies variability in all its forms and, in essence, is an instrument that allows us to analyze variable phenomena and detect small, but nevertheless important, differences. The instrumental character of this science made Statistics a fundamental tool for the study of biological and clinical phenomena, but the purpose of this discussion is to focus on the fact that Statistics, either directly or indirectly, is presently the basis of virtually all medical decision-making processes and, consequently, has had a major influence on clinical practice itself. Disease prevalence, the consideration of risk factors, for instance, which is information of great importance in the process of diagnosis, is obtained through studies that are based in statistical methodologies. It is, however, in the decision-intensive processes of selecting diagnostic examinations, choosing the best therapy and evaluating the prognostic implications, that Statistics have had a more direct impact on clinical practice. In modern Medicine, Statistics may no longer be seen as a set of techniques that are applied in scientific research. Rather, Statistics should be understood as the appropriate language for describing and discussing observed phenomena.

Diagnosis↗
PubMedDate not supplied

Juvenile rheumatoid arthritis--assessment.

The assessment of overall health status of a child with juvenile rheumatoid arthritis (JRA) is complex and multi-dimensional. The general physical examination is complemented by a rheumatological evaluation that includes determination of articular indices of inflammation and duration of inactivity stiffness. Laboratory assessment plays a critical role in monitoring side effects of pharmacologic management, but is limited in its ability to portray accurately the degree of active inflammation. Newly measureable indicators of inflammatory activity, such as serum cytokine and soluble cytokine receptors will likely become part of routine laboratory assessment in the future. Radiographs remain a useful tool for assessing disease progression, but may be replaced in the future by magnetic resonance imaging. In recent years, rheumatologists have realized that measurement of overall physical and psycho-social functional ability, quality of life, and pain are major descriptors to consider during routine follow-up. They are also critical in the assessment of long-term clinical effectiveness. The importance of nutritional assessment has also been realized. This section seeks to describe some of the methodologic approaches currently used to assess the variables mentioned above, and includes a brief discussion of the evolving instrumentation which attempts to measure variables of a more cognitive or subjective aspect.

Adolescent↗
PubMed2000

Multisystemic therapy: monitoring treatment fidelity.

The challenges of specifying a complex and individualized treatment model and measuring fidelity thereto are described, using multisystemic therapy (MST) as an example. Relations between therapist adherence to MST principles and instrumental and ultimate outcome variables are examined, as are relations between clinical supervision and therapist adherence. The findings provide modest support for the associations between MST adherence measures and instrumental and ultimate outcomes. Results also show that adherence can be altered when clinical supervision and adherence monitoring procedures are fortified. The modest associations between adherence measures and youth outcomes argue for further refinement and validation of the MST adherence measure, especially in light of the well-established effectiveness of MST with challenging clinical populations and the increasing dissemination of MST programs.

Family Relations↗
PubMed1999

Defining disease activity in ankylosing spondylitis: is a combination of variables (Bath Ankylosing Spondylitis Disease Activity Index) an appropriate instrument?

OBJECTIVE: Disease activity has been defined using a self-administered instrument, focusing on fatigue, axial pain, peripheral pain, enthesopathy and morning stiffness [Bath Ankylosing Spondylitis Disease Activity Index (BASDAI)]. This validated instrument is simple and takes 40 s to complete, but whether the index is an accurate expression of the component parts, or whether additional weighting would enhance its efficacy, is unclear. METHODS: Four hundred and seventy-three patients with ankylosing spondylitis received placebo or active non-steroidal anti-inflammatory drug (NSAID) for 6 weeks, and changes between entry and completion were captured by BASDAI and the individual components. Principle component analysis (PCA) was used to explore the best combinations of variables in decreasing order of explained total dispersion and to assess whether a single sum (or algebraic expression) best defined disease activity status. RESULTS: At entry, the correlation between BASDAI and the first axis was 0.99, 0.11 with the second, and zero thereafter. Data at study end and relating to change revealed a 100% correlation (R = 1) between the first axis and the sum, with zero for the remainder. CONCLUSIONS: The data support BASDAI as being a valid and appropriate composite to define disease activity in ankylosing spondylitis. Developed as a simple sum of its components, BASDAI has excellent content validity.

Aged↗
PubMed2003

Does 'like predict like' when patients discharged from high secure hospitals re-offend? An instrument to describe serious offences.

BACKGROUND: The statement that past behaviour is the best predictor of future behaviour has empirical support in respect of whether an individual will, or will not, commit a criminal offence. People who have offended in the past are more likely to offend in the future. The aims of this study were to develop an instrument and to examine whether the same statement applies in respect of the nature and circumstances of successive offences committed by the same person. METHOD: A rating instrument to describe seven variables relating to the nature and circumstances of a serious offence, the SODI, was developed by the authors. Inter-rater reliability was measured when the instrument was applied to 80 offences committed by 40 patients leaving high secure hospitals. The data were examined for evidence of similarity in the nature and circumstances of successive offences. RESULTS: For five of the seven items of the instrument the kappa coefficients for inter-rater reliability were > 0.65. No significant associations, in terms of SODI ratings, were found between the offence that led to hospital admission and that which was committed after discharge. CONCLUSIONS: The SODI is a reliable instrument for the description of serious offences committed by this group. Risk assessments in psychiatry should be informed by an awareness that in only a proportion of cases will the nature and circumstances of any serious re-offence resemble the nature and circumstances of the offence which contributed to a patient's admission to hospital.

Crime↗
PubMed1983

Automation of a cryopreservation apparatus.

An organ preservation apparatus was interfaced to a process-control computer and automated. The flexibility of the equipment was demonstrated by running simultaneous dual sets of experiments under multiple and variable conditions. The computer-control program was written in a new high-level language, Real Time Extended Basic (RTEB), which allowed interactive calibration of the instruments, accurate control of variables, and modification of parameters during run time. A series of preliminary tests in the areas of normothermia, hypothermia, cooling of isolated rat hearts, and cryoprotectant toxicity were performed successfully. This work describes the apparatus and computer program in use.

Analog-Digital Conversion↗
PubMedDate not supplied

Development of cultural belief scales for mammography screening.

PURPOSE/OBJECTIVES: To develop instruments to measure culturally related variables that may influence mammography screening behaviors in African American women. DESIGN: Instrumentation methodology. SETTING: Community organizations and public housing in the Indianapolis, IN, area. SAMPLE: 111 African American women with a mean age of 60.2 years and 64 Caucasian women with a mean age of 60 years. METHODS: After item development, scales were administered. Data were analyzed by factor analysis, item analysis via internal consistency reliability using Cronbach's alpha, and independent t tests and logistic regression analysis to test theoretical relationships. MAIN RESEARCH VARIABLES: Personal space preferences, health temporal orientation, and perceived personal control. FINDINGS: Space items were factored into interpersonal and physical scales. Temporal orientation items were loaded on one factor, creating a one-dimensional scale. Control items were factored into internal and external control scales. Cronbach's alpha coefficients for the scales ranged from 0.76-0.88. Interpersonal space preference, health temporal orientation, and perceived internal control scales each were predictive of mammography screening adherence. CONCLUSIONS: The three tested scales were reliable and valid. Scales, on average, did not differ between African American and Caucasian populations. IMPLICATIONS FOR NURSING: These scales may be useful in future investigations aimed at increasing mammography screening in African American and Caucasian women.

Adult↗