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At least 19 recordsLinked to original sources
PubMed1976

Age differences in personality structure: a cluster analytic approach.

A cluster analytic approach was used to determine possible age differences in the structure of personality as measured by the Cattell Sixteen Personality Factor Questionnaire. Subjects were 969 adult male volunteers, originally divided into three groups: 25 to 34, 35 to 54, and 55 to 82. Two familiar dimensions of personality, Anxiety-Adjustment and Introversion-Extraversion, were found to be cross sectionally stable. A third cluster dimension, interpreted as openness to experience, showed age-related differences. Young subjects showed openness to feelings; middle-aged subjects showed openness to ideas; and old subjects showed a balanced openness to both feelings and ideas. Repartitioning of the sample into two groups (ages 25 to 43 and 44 to 82), and three groups (25 to 39, 40 to 47, and 48 to 82) confirmed these age differences in the third cluster. The interpretation of the third cluster is discussed in terms of Jung's concepts of psychological functions.

Age Factors↗
PubMed1990

Current analytical approaches to measuring blood analytes.

In recent years, laboratory testing in the critical-care setting has increased, a trend due, in part, to the evolution of electrochemical sensors. Various innovations have extended sensor lifetimes, reduced sensor maintenance, and led to the development of single-use and unit-use disposable sensors. These sensor technologies allow the accurate and precise determination, either at or near the bedside, of several analytes including pO2, pCO2, pH, Na, K, Cl, ionized calcium, hematocrit, total hemoglobin, and glucose. Use of these new systems, however, has raised new issues regarding sensor calibration and sample handling and collection. The number of direct-reading analyzers for electrolyte determinations has also increased dramatically. Issues regarding calibration of ion-selective electrodes (ISEs) for Na/K have also been raised after demonstrations of between-instrument variation. Recently, collaborative efforts between eight ISE instrument manufacturers and the National Institute of Standards and Technology resulted in the development of a Standard Reference Material, SRM 956, for the purpose of standardizing direct-reading Na/K ISEs to the flame photometer. Other widely used technologies that provide noninvasive, continuous monitoring include pulse oximetry and transcutaneous gas electrodes. These trends are expected to continue and to produce a new generation of electrochemical and optical sensors.

Autoanalysis↗
PubMed1990

New in vitro analytical approaches for clinical chemistry measurements in critical care.

The effective management of patients in intensive care units, operating rooms, and emergency rooms requires frequent measurement of a select group of analytes, preferably at or near the patient's bedside. Tests recognized as being essential for such management include blood gases and related variables (pH, pO2, pCO2, HCO3-, hematocrit/hemoglobin, O2 saturation), electrolytes (Na+, K+, Ca2+, Cl-), and in some cases, certain metabolites (glucose, lactate, urea, creatinine). This report describes the measurement principles, practical instrumental designs, analytical performance, and limitations of several newer electrochemical sensor-based approaches useful for in vitro determination of these species in undiluted whole-blood samples. Considerable attention is given to the most recent advances in ion-selective electrode technology as they relate to blood gas and electrolyte determinations. Similar attention is given to modern enzyme-electrode techniques, which are useful for direct measurements of metabolites in whole blood. The challenges of integrating these new analytical methods into convenient, multi-analyte, user-friendly, bedside or stat-lab instruments are also discussed.

Autoanalysis↗
PubMed1975

Analytical approach for depth dose calculations (60Co beams with fixed source-target distance).

A method is described to calculate depth dose distribution to a principal plane using analytical formulas for 60Co teletherapy units and constant source-to-target distance. The formulas were derived from experimental measurements taking into consideration the obliquity of the beam. For the purposes of dose calculation the beam was divided into primary and scattered components. A computer program incorporating the formulas was developed for an IBM 360/67 computer. Dose distributions computed and obtained from experimental measurements were in good agreement. The computer program is now in use for treatment planning, including rotational techniques.

Cobalt Radioisotopes↗
PubMed1990

Analytical approaches to the study of monoclonal antibody stability.

The stability of two purified monoclonal antibodies, MN12 and WT31, was investigated. The monoclonal antibodies were incubated for 32 days at different pH values (ranging from 3.0 to 10.0) at 4 and 37 degrees C. Various analytical methods were used to assess changes in physicochemical properties of the proteins. The monoclonal antibodies were more susceptible to degradation at 37 degrees C than at 4 degrees C. At low pH irreversible precipitation occurred. Decomposition of the proteins was enhanced at increasing pH values in the alkaline range. This was concluded from mouse IgG-specific and antigen-specific enzyme-linked immunosorbent assays, flow cytometry, analytical gel permeation chromatography, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, isoelectric focusing, and immunoblotting. No substantial change in the apparent affinity constant of MN12 was observed, as determined by an affinity enzyme-linked immunosorbent assay. Fluorescence spectra, fluorescence polarization values, and fluorescence quenching parameters of MN12 and WT31 were not substantially affected, indicating that no major irreversible conformational changes had occurred. It was concluded that each of the techniques used has only limited value for stability assessment of monoclonal antibodies and, hence, that the application of several analytical techniques is essential to gain insight into monoclonal antibody stability.

Animals↗
PubMed1992

Life-style and substance use among male African-American urban adolescents: a cluster analytic approach.

Cluster analyzed four variables: school attendance, employment, church attendance, and delinquency, to develop life-style profiles. Data from 218 African-American urban adolescents were used in the study. Five meaningful clusters were retained and subjected to criterion validity analyses using measures of spirituality, participation in a voluntary organization, self-esteem, and friend's substance use. The five clusters were then compared on cigarette, alcohol, marijuana, and hard drug use. The results suggest that a life-style that includes an adaptive compensatory behavior component may be more adaptive than a life-style that does not include compensatory behavior. For example, youths who left high school before graduation but were involved in church reported less alcohol and substance use than youths who left school and were not involved in any meaningful instrumental activity. Implications for intervention and future research on high-risk behaviors are discussed.

Adolescent↗
PubMed1990

Heart rate variability in diabetic patients during orthostatic load--a spectral analytic approach.

Spectral analysis of heart rate variability (HRV) was used to assess the autonomic nervous control of cardiac function during orthostatic load in insulin-dependent diabetic patients and healthy subjects. The diabetic patients were divided into three groups: diabetics without neuropathy (group 1), diabetics with peripheral neuropathy (group 2), and diabetics with peripheral and autonomic neuropathy (group 3). Resting mid-frequency (MF, 0.05-0.15 Hz) and respiration-related (RF, power around respiration rate) HRV were significantly lower in group 2 and 3 diabetics than in controls, indicating a reduced parasympathetic nervous system influence on the heart. Standing MF and RF spectral power data were significantly lower in all diabetic groups than in controls, suggesting marked alterations in the autonomic cardiovascular control during a mild physical load not only in symptomatic diabetics but also in patients with no signs and symptoms of neuropathy. The difference between supine and standing MF power, an estimate of beta-adrenergic influence on the heart, was significantly lower in all diabetic subject groups studied than in controls. This suggests a reduced sympathetic nervous system influence on the heart in diabetic patients. Our data suggest that computerized spectral analysis of HRV during orthostatic load seems to be a very sensitive method of evaluating of the autonomic nervous systems influence on the heart in patients suffering from diabetes mellitus.

Adult↗
PubMedDate not supplied

Analytical approach to mathematical modelling of the isometric contraction of the hypertrophied myocardium.

It is attempted on the basis of the Hill two-element model to simulate mathematically the rising phase of the isometric mechanogram in the pressure-hypertrophied rat myocardium (Goldblatt II). The evaluation is based on the experimentally determined force-velocity relation as well as on the characteristic of the series-elastic stiffness. The changes in the isometric mechanogram of the hypertrophied heart muscle observed in the experiment can be mathematically predicted solely by means of the alterations in the force-velocity relationships induced by the hypertrophy, whereby the characteristic of the series-elastic stiffness is considered to be unchanged.

Cardiomegaly↗
PubMed1990

Toward an identification of mechanical parameters initiating periosteal remodeling: a combined experimental and analytic approach.

The ability of bone to adapt to its mechanical environment is well recognized, although the specific mechanical parameters initiating or maintaining the adaptive responses have yet to be identified. Recently introduced mathematical models offer the potential to aid in the identification of such parameters, although these models have not been well validated experimentally or clinically. We formulated a complementary experimental/analytic approach, using an animal model with a well-controlled mechanical environment combined with finite element modeling (FEM). We selected the functionally isolated turkey ulna, since the loading could be completely characterized and the periosteal adaptive responses subsequently monitored and quantified after four and eight weeks of loading. Known loads input into a three-dimensional, linearly elastic FEM of the ulna then permitted full-field mechanical characterization of the ulna. The FEM was validated against a normal strain-gaged turkey ulna, loaded in vivo in an identical fashion to the experimental ulnae. Twenty-four candidate mechanical parameters were then compared to the quantified adaptive responses, using statistical techniques. The data supported strain energy density, longitudinal shear stress, and tensile principal stress/strain as the mechanical parameters most likely related to the initiation of the remodeling response. Model predictions can now suggest new experiments, against which the predictions can be supported or falsified.

Adaptation, Physiological↗
PubMed1991

Seasonal variations in mood and behavior in the general population: a factor-analytic approach.

In a mailed survey conducted at four centers--Nashua, NH; New York, NY; Washington, DC; and Sarasota, FL--1,671 respondents provided information on monthly variations in 10 behavioral categories representing extremes in the areas of mood, socializing, appetite, weight gain/loss, and sleep length. A 10-factor solution revealed the following factors: (1) a winter weight gain factor; (2) a winter depression factor; (3) a winter hypersomnia factor; (4) a summer weight gain factor; (5) a summer hypersomnia factor; (6) a summer depression factor; (7) a winter socializing factor; (8) a winter weight loss factor; (9) a fall depression factor; and (10) a possibly mixed factor. Factors consistent with winter seasonal affective disorder were positively correlated with latitude, while those consistent with summer seasonal affective disorder were negatively correlated with latitude.

Affect↗
PubMed1990

An analytic approach to optimized retracted missing tissue compensators.

The introduction of an attenuating medium into a photon beam serves both to reduce the intensity of the primary beam and to create secondary radiation due to scatter. When retracted missing tissue compensators are employed to compensate for irregular surface contour or internal inhomogeneities, they are often fabricated without regard to the scattered radiation that they introduce into the system. The study of a mathematically describable conical geometry has clearly demonstrated the need for improved compensator design. Experimental results obtained with this geometry can be reproduced with good agreement, using theoretical calculations based on primary and first order scattered radiation. This method of analysis may be extended to predict the shape of a compensator which will produce an optimized dose distribution at a given depth in a phantom, equivalent to that which would be obtained when an irregular surface is filled with unit density material (bolus), producing a flat surface. An optimized compensator was constructed based on these theoretical considerations and excellent agreement was observed between theory and experiment. Dramatic improvement in the restoration of bolus dose is obtained with this optimized compensator. Finally, an anthropomorphic phantom of the neck region has been constructed and the performance of a compensator designed according to current clinical methods for this geometry has been evaluated. The performance of an optimized compensator specific to this geometry is presented and good agreement between theoretical predictions and experimental results is observed. Dramatic improvement in bolus dose restoration over that obtained with the clinically designed compensator is realized.

Humans↗
PubMed1990

Hippuric acid and 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid in serum and urine. Analytical approaches and clinical relevance in kidney diseases.

Hippuric acid (HA) and 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid (FA) were determined in serum, plasma, ultrafiltrate and urine by gas chromatography (GC), high-performance liquid chromatography and GC with mass-selective detection, and the methods were compared. As determined by affinity chromatography and analysis of serum and ultrafiltrate, 0.5% of FA in serum occurs free and 99.5% is bound to albumin. In haemodialysed patients with chronic renal failure, the plasma levels of HA and FA are elevated in comparison with normal controls and hospital patients without kidney diseases: HA, 11.1 +/- 5.7 mg/dl (n = 86); FA, 1.9 +/- 1.2 mg/dl (n = 86). Gradual increases in HA in serum, depending on the creatinine concentrations, are found in non-dialysed patients with chronic renal failure. By haemodialysis and haemofiltration the HA levels are lowered (53-66 and 30-36%, respectively), whereas FA is not dialysable.

Chromatography, Gas↗
PubMed1977

A systems-analytical approach to macro-evolutionary phenomena.

Two sets of evolutionary phenomena find no explanation through current theory. For the static phenomena (such as homology, homonomy, systematic weight, and "Type") there is no causal base, although these principles are responsible for all phenomena of predictable order in the living world. The dynamic phenomena (such as homodynamy, coadaptation, parallel evolution, orthogenesis, Cartesian transformation, typostrophy, hetermorphosis, systemic mutation, and spontaneous atavism) have no causal explanation, although they are responsible for all directed phenomena in macroevolution. These phenomena share one unifying principle which can be explained by a system theory of evolution based on, but extending, the current synthetic theory. This system theory envisages feedback conditions between genotype and phenotype by which the chances of successful adaptation increase if the genetic units, by insertion of superimposed genes, copy the functional dependencies of those phene structures for which they code. This positive feedback of the adaptive speed (or probability) within a single adaptive direction is compensated by negative feedback in most of the alternative directions. The negative feedback operates as selection not be environmental but by systemic conditions developed by the organization of the organism. The consequences are an imitatively organized system of gene interractions, the rehabilitation of classical systematics, the reality of the "natural system," and, in general, the resolution of the contradiction between neodarwinists and their critics, between reductionists and holists, between "a priori" and "a posteriori" views, between idealism and materialism, and between the notions of freedom and of purpose in evolution.

Biological Evolution↗