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At least 775 records · Page 43Linked to original sources
PubMed1995

Impact of electroosmosis on isotachophoresis in open-tubular fused-silica capillaries: analysis of the evolution of a stationary steady-state zone structure by computer simulation and experimental validation.

A dynamic computer model for simulation of open-tubular capillary electrophoresis that includes in situ calculation of electroosmosis along the fused-silica capillary column has been applied to the characterization of an anionic isotachophoretic system in presence of a cathodic electroosmotic flow. For each column segment, electroosmosis is calculated with the use of a wall mobility, the voltage gradient and the degree of dissociation of the silanol surface groups of the capillary wall. Then, the bulk capillary flow is taken to be the average of all of the segment flows and considered to represent a plug flow. This simple approach enables the combined simulation of the temporal behavior of an isotachophoretic zone structure in presence of electroosmosis. For a model anionic isotachophoretic configuration at pH 6, simulation data reveal the asymptotic formation of a stationary steady-state zone configuration in which electrophoretic and electroosmotic zone displacements are opposite and of equal magnitude. The position of the stationary boundaries are predicted to be dependent on the selected wall pK and mobility values. For two different instruments, qualitative agreement between experimental data and simulation results obtained with a wall pK between 5 and 6 is demonstrated. However, for the two experimental setups, significant differences in electroosmotic pumping (i.e. wall mobility values) are noted.

Anions↗
PubMed2006

Factor structure of the Comprehensive Adolescent Severity Inventory (CASI): results of reliability, validity, and generalizability analyses.

This article describes the results of psychometric work conducted on the Comprehensive Adolescent Severity Inventory (CASI) among 205 in-treatment substance-abusing adolescents. Four dimensions, each composed of component subscales, resulted from standard psychometric analyses: Chemical Dependency, Psychosocial Functioning, Delinquency, and Risk Behavior. Each dimension had high internal consistency (alpha coefficients for the component subscales comprising each clinical dimension range from .78 to .96) and test-retest reliability (intraclass correlation coefficients range from .88 to .96 and all are significant at p < .0001.). Concurrent validity and specificity of the CASI dimensions also were found: significant and substantial variance in NIMH Diagnostic Interview Schedule for Children-Revised (DISC-IV) and Brief Symptom Inventory (BSI) scores was associated with relevant CASI dimensions; CASI dimensions that theoretically should show no significant relationship with divergent pathology were not associated. The dimensions forecasted substantial variance in adolescent functioning posttreatment discharge, supporting predictive validity. Finally, the dimensional clinical structure was found to be generalizable over male and female adolescents, younger and older adolescents, and adolescents from different ethnic groups. These results provide further evidence for the CASI's promise in research and practice as an adolescent-specific assessment instrument that comprehensively assesses multidimensional areas of functioning within a developmental context of measurement. Limitations of the study along with future work currently being conducted on the CASI are discussed.

Adolescent↗
PubMed2002

A multidimensional measure of caregiving appraisal: validation of the Caregiver Appraisal Scale in traumatic brain injury.

OBJECTIVE: To investigate the factor structure and concurrent validity of the Caregiver Appraisal Scale (CAS) in a sample of caregivers of adults with traumatic brain injury (TBI). DESIGN: Prospective cohort study. SETTING: Two sites: (1) Outpatient clinics associated with a comprehensive inpatient brain injury rehabilitation program and (2) a comprehensive residential postacute rehabilitation program in the Southern United States. PARTICIPANTS: One hundred forty-nine caregivers of adults with TBI enrolled in the TBI Model Systems Project and 92 caregivers of adults with TBI admitted to a residential postacute rehabilitation program. Most caregivers were women and either parents or spouses of the injured person. MAIN OUTCOME MEASURES: Caregiver Appraisal Scale (CAS); Subjective Burden Scale (SBS); Objective Burden Scale (OBS); General Health Questionnaire (GHQ). RESULTS: Principal components analysis with varimax rotation yielded four factors: perceived burden (PB), caregiver relationship satisfaction (CRS), caregiving ideology (CI), and caregiving mastery (CM), which were found to be fairly stable across treatment settings. Adequate concurrent validity was demonstrated for the perceived burden factor, and adequate internal consistency was found for three of four scales. CONCLUSIONS: Preliminary support for the use of the CAS in caregivers of adults with TBI was obtained. However, further scale development, particularly for the CM factor, will likely improve the stability and usefulness of this instrument.

Adolescent↗
PubMed1989

A factorial, reliability, and validity study of the Devereux Elementary School Behavior Rating Scale.

This investigation explored the factor structure, reliability, and validity of the Devereux Elementary School Behavior Rating Scale, employing a large (n = 648) sample of children. Factor analysis suggested that the Devereux scale can be described by four factors, which were named Disruptive-Oppositional, Poor Comprehension-Disattention, Cooperative-Initiating, and Performance Anxiety. All four factors showed high internal consistency, and three of the four were stable over a 17-mo. period. Correlations of the four factors with academic achievement, IQ, socioeconomic status, and peer ratings of social competence are presented. All four factors showed significant relations with these variables, with Poor Comprehension-Disattention the strongest of all. Multiple regression analysis indicated that the Poor Comprehension-Disattention factor accounted for significant variance in academic achievement even after IQ was taken into account. Large differences between classroom means on the factor scores suggested that Devereux ratings for individual students may need to be interpreted cautiously.

Achievement↗
PubMed2004

The ADP-IV questionnaire: differential validity and concordance with the semi-structured interview.

The Assessment of DSM-IV Personality Disorders questionnaire (ADP-IV) is a self-report measure of the DSM-IV Axis II personality disorders (PDs). The ADP-IV assesses for each DSM-IV criterion its typicality as well as the accompanying distress and impairment. This study investigates two important aspects of the construct validity of the ADP-IV: (a) the differential validity (i.e., the ability to differentiate between a sample of the general Flemish population ( n = 659) and a sample of psychiatric inpatients ( n = 487) with a high prevalence of clinical PD diagnoses, and patients with and without a PD in the psychiatric sample; (b) the convergent validity with the SCID-II semi-structured interview in a population of psychiatric inpatients ( n = 59). The results indicate a good differential validity: the dimensional scales and the categorical measures discriminated well between both groups and between patients with and without a PD diagnosis in the psychiatric sample. Concerning the concordance with the SCID-II, a decent level of agreement is exemplified by a correlation of.67 between the dimensional total scores of both instruments and by kappa coefficients for an "any" Axis II diagnosis at the.50 level. In conclusion, the results indicate that the ADP-IV is an efficient method for assessing PD in dimensional and categorical ways.

Adolescent↗
PubMed1998

Factor structures of the Zung Self-Rating Depression Scale (SDS) for undergraduates.

In order to categorize the items of the Zung Self-Rating Depression Scale (SDS) so as to allow the construction of subscales, the Japanese version of the SDS was administered to a total of 2,258 undergraduates. Principal-component analyses of the SDS extracted three factors interpretable as cognitive, affective, and somatic symptoms. The SDS was then administered to 597 undergraduates in order to cross-validate the factor structures. The coefficient of congruence and the goodness-of-fitness index generated by a confirmatory factor analysis showed good cross-validity of the factor structures.

Adolescent↗
PubMed1998

Use of structural equation modeling to test the construct validity of the SF-36 Health Survey in ten countries: results from the IQOLA Project. International Quality of Life Assessment.

A crucial prerequisite to the use of the SF-36 Health Survey in multinational studies is the reproduction of the conceptual model underlying its scoring and interpretation. Structural equation modeling (SEM) was used to test these aspects of the construct validity of the SF-36 in ten IQOLA countries: Denmark, France, Germany, Italy, the Netherlands, Norway, Spain, Sweden, the United Kingdom, and the United States. Data came from general population surveys fielded to gather normative data. Measurement and structural models developed in the United States were cross-validated in random halves of the sample in each country. SEM analyses supported the eight first-order factor model of health that underlies the scoring of SF-36 scales and two second-order factors that are the basis for summary physical and mental health measures. A single third-order factor was also observed in support of the hypothesis that all responses to the SF-36 are generated by a single, underlying construct--health. In addition, a third second-order factors, interpreted as general well-being, was shown to improve the fit of the model. This model (including eight first-order factors, three second-order factors, and one third-order factor) was cross-validated using a holdout sample within the United States and in each of the nine other countries. These results confirm the hypothesized relationships between SF-36 items and scales and justify their scoring in each country using standard algorithms. Results also suggest that SF-36 scales and summary physical and mental health measures will have similar interpretations across countries. The practical implications of a third second-order SF-36 factor (general well-being) warrant further study.

Cross-Cultural Comparison↗
PubMed2005

Molecular simulations for the conformational assessment of a porphyrin-fullerene dyad in different environments.

Conformational space of a porphyrin-fullerene dyad with the donor and acceptor connected by a relatively flexible linker is studied by molecular dynamics simulations in both non-polar and polar solvents, as well as in vacuum. The most probable conformations obtained from the vacuum MD simulations were optimized with semi-empirical (SE) and density functional theory (DFT) methods and the extent of the structural changes is assessed. The computational results indicate the co-existence of different conformers in both polar and nonpolar solvents showing agreement with experimental results. The most probable vacuum conformations at 300 K are similar to the ones at 0 K, while the structures most often observed in the solvents show less compact conformations. Optimization with SE and DFT calculations leads to structures, which represent relatively well the folded conformations in solvent, which validates the electronic structure calculations relevant to describing photoinduced electron-transfer in H2P-O34-C60.

Computer Simulation↗
PubMed2005

Protein structural change upon ligand binding: linear response theory.

A simple formula based on linear response theory is proposed to explain and predict the structural change of proteins upon ligand binding. By regarding ligand binding as an external perturbation, the structural change as a response is described by atomic fluctuations in the ligand-free form and the protein-ligand interactions. The results for three protein systems of various sizes are consistent with the observations in the crystal structures, confirming the validity of the linear relationship between the equilibrium fluctuations and the structural change upon ligand binding.

Acetyl Coenzyme A↗
PubMed1997

Overall maturity of object relations as assessed by the McGill Object Relations Scale.

The McGill Object Relations Scale (MORS) is an instrument for assessing levels of drive-based object relations along a continuum of positions representative of psychosexual development. Its theoretical foundations as well as empirical antecedents are presented, and its rating procedure is demonstrated through a case application. The MORS was applied, by five experienced psychiatrists, to 67 adult patients seeking psychoanalytic psychotherapy, in order to assess interrater reliability, internal structure, and construct validity. Results indicate that overall maturity of object relations stems from structural indices of self-object differentiation determined by a particular configuration of many positions, rather than from the thematic aspects included in the individual psychosexual positions.

Adult↗
PubMed2005

Reliability and validity of the French version of the tobacco craving questionnaire.

OBJECTIVES: (1) To assess the factorial structure, reliability and validity of the French language version of the Tobacco Craving Questionnaire (TCQ), a multidimensional, self-report instrument evaluating tobacco craving, to allow its use in French-speaking populations. (2) To compare the two different language versions of the same instrument in 2 independent samples from 2 cultures in 2 distinct time periods. METHODS: The French TCQ was administered to 226 current cigarette smokers after at least 2 h of abstinence. RESULTS: Despite the substantial difference in population characteristics between the French and American samples of smokers, both exploratory and confirmatory factor analyses indicated that the French version was best described by a 4-factor solution, similar to the original English version. Reliability estimates were 0.83, 0.79, 0.69 and 0.66 for the French and 0.82, 0.70, 0.75 and 0.48 for the English version for 'emotionality' (factor 1), 'expectancy' (factor 2), 'compulsivity' (factor 3) and 'purposefulness' (factor 4), respectively. The 4 factors accounted for 11.6, 17.1, 9.0, and 9.5% of the total variance in emotionality, expectancy, compulsivity, and purposefulness, respectively, for the French compared to 14.2, 12.5, 14.4 and 5% of the total variance for the English version, respectively. CONCLUSION: The French version of the TCQ is as valid and reliable instrument as the original English version and assesses the same 4 dimensions of craving for tobacco.

Adult↗
PubMed2000

Statistical dynamical direct methods. I. The effective kinematical approximation

While it is known that the kinematical approximation works poorly if at all for transmission electron diffraction, substantial success has been achieved over the last few years in applying it via direct methods to determine atomic structures. This raises an interesting quandary; is the established theory of electron diffraction wrong, or are the apparent successes mirages? The intention of this note is to look more deeply into this question and it is found that the correct answer is neither of the above. Beyond vanishingly thin samples when the kinematical approximation holds rigorously, the distribution of phases can remain effectively kinematical; the summation operator(0) distribution given by the sum of the phase of +g and -g reflections remains peaked, albeit not at zero phase, and has a relatively narrow distribution. This fact is shown via both exploiting prior works on including anomalous-scattering effects into direct methods, and numerical calculations. Provided that the summation operator(0) distribution remains narrow, direct methods and indeed structural refinements have some validity. Even larger unit-cell structures with close to statistically random atomic positions do not approach a kinematical limit but instead an effective statistical kinematical approximation. While there are similarities to what there is in conventional (kinematical) direct methods, there remain major differences; for instance, positivity is no longer a valid constraint and the scattering need not be dominated by heavy atoms.

Journal Article↗
PubMed2005

Validation of the Chinese version of the Oswestry Disability Index.

This study aimed to collect evidence on the structural and substantive validity, and test-retest reliability of the Chinese version of the Oswestry Disability Index (CODI). Seventy-nine patients suffering from chronic low back pain were assessed with the CODI. The results of explorative factor analysis primarily suggested a single-factor structure with nine out of 10 items (factor loading = 0.66-0.79). The sex life item was found to load on a different factor. The Cronbach's alpha of all 10 items was 0.81 (p<0.05). When the sex life item was removed from the analysis, the alpha value was increased to 0.89 (p<0.05). The test-retest reliability was estimated based on 56 participants who completed two administrations of CODI in 48 hours. The intraclass correlation coefficient (ICC) computed for the total CODI scores was 0.86 (95% C.I. = 0.81-0.91). The reliability estimated for the item scores using Kappa statistics ranged from a high of k=0.80 for the sitting item to a low of k=0.49 for the traveling item. Kappa statistics were not available for three items. The Chinese version of the Oswestry Disability Index demonstrated satisfactory validity and test-retest reliability, and so could be considered as an appropriate instrument for assessing chronic back pain-related disability in Chinese patients in Hong Kong. Further research should address the cross-cultural and measurement issues in regard to sex life in order to further improve the test content of the instrument.

Adult↗
PubMed2004

Agitated behaviours among the institutionalized elderly with dementia: validation of the Korean version of the Cohen-Mansfield Agitation Inventory.

OBJECTIVES: To analyze the factor structure, the criterion validity, the internal consistency, inter-rater reliability and test-retest reliability of the Korean version of Cohen-Mansfield Agitation Inventory, to provide data on the frequency and distribution of agitated behaviours, and to compare patterns of agitated behaviours among the institutionalized elderly with Alzheimer's disease (AD) or Vascular dementia (VaD). METHODS: The Korean version of the Cohen-Mansfield Agitation Inventory (CMAI-K) was administered to a total of 257 elderly with AD or VaD in a nursing home in Seoul, Korea. Three kinds of reliability and criterion validity were tested. Factor analysis using principal component analysis with the varimax rotation was performed. To identify different patterns of agitated behaviours, multiple logistic regression analysis was used. RESULTS: This study demonstrated satisfactory reliability and validity for the CMAI-K as an instrument measuring agitation in Korean dementia sufferers in nursing homes. Eighty-three percent of the subjects manifested one or more agitated behaviours at least once a week. Factor analysis yielded four subtypes of agitation: physically aggressive behaviours, physically nonaggressive behaviours, verbally agitated behaviours, and hiding/hoarding behaviours. CONCLUSION: These results indicate that the CMAI-K is a reliable and valid instrument to measure agitated behaviours in Korean elderly with AD or VaD. These results validate and expand previous research on the agitation in dementia, and guide in the development of interventions.

Aged↗
PubMed2003

Ab-initio prediction and reliability of protein structural genomics by PROPAINOR algorithm.

We have formulated the ab-initio prediction of the 3D-structure of proteins as a probabilistic programming problem where the inter-residue 3D-distances are treated as random variables. Lower and upper bounds for these random variables and the corresponding probabilities are estimated by nonparametric statistical methods and knowledge-based heuristics. In this paper we focus on the probabilistic computation of the 3D-structure using these distance interval estimates. Validation of the predicted structures shows our method to be more accurate than other computational methods reported so far. Our method is also found to be computationally more efficient than other existing ab-initio structure prediction methods. Moreover, we provide a reliability index for the predicted structures too. Because of its computational simplicity and its applicability to any random sequence, our algorithm called PROPAINOR (PROtein structure Prediction by AI an Nonparametric Regression) has significant scope in computational protein structural genomics.

Algorithms↗
PubMed1986

The NCI Drug Information System. 2. DIS Pre-Registry.

The Pre-Registry Module of the Drug Information System (DIS) is a staging area through which all new compounds are passed prior to acquisition and testing. Several methods are available for the entry of structures into the Pre-Registry; all involve built-in data validation. Newly entered structures are examined by computer programs for structural novelty and potential for anticancer activity. For those compounds that proceed to acquisition, the various acquisition steps, such as letter writing and record updating, are performed automatically. When a sample is obtained, the entire Pre-Registry record is updated and moved forward into the permanent DIS chemistry files.

Antineoplastic Agents↗
PubMed1999

Men's sexual self-schema.

Sexual self-schemas are cognitive generalizations about sexual aspects of oneself. In Part 1, a measure of men's sexual self-schema is developed. Studies of test-retest and internal consistency reliability and validity studies of factor analysis, internal structure, convergent and discriminant validity, process, group difference, and change are provided. The construct consists of 3 dimensions: passionate-loving, powerful-aggressive, and open-minded-liberal traits. In Part 2, the data suggest that men's sexual schema is derived from past sexual experience, is manifest in current sexual experience, and guides future sexual behavior. In Part 3, the data document the cognitive processing aspects of sexual schema. Consistent with the investigators' schema research with women, these data substantiate the importance of cognitive representations of sexuality.

Adult↗