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PubMedDate not supplied

An empirical approach to projecting regional blood need.

An empirical mathematical model was developed for projecting monthly and yearly regional blood utilization. Based upon 1974 data from eight Clark County, Nevada hospitals offering a total of 1,389 medical-surgical, and pediatric beds, an unadjusted projection deviated minus 7.2 per cent from the actual 1975 regional blood utilization. Adjusted projections, modified by an averaging technique that utilized previous month's blood utilization along with historical utilization data, resulted in an annual projection that deviated minus 1.9 per cent from the actual blood use. The adjusted monthly mean projection did not differ significantly from the actual mean monthly blood use. This approach appears to be of value in regional planning for long- and short-range blood needs.

Blood Banks↗
PubMed1984

Psychoanalytic concepts of eating disorders: an empirical approach with a semantic differential (Ertel).

To study empirically some psychoanalytic assumptions concerning aspects of the oral character and manifestations of fixation and regression, 61 neurotic inpatients at a psychotherapeutic clinic were investigated using a semantic differential technique (Ertel). Each patient was judged by the differential technique on the basis of 12 object representations which, in respect to the psychoanalytic theory of development, are postulated to have connections with the oral stage. A connotative proximity in the semantic space was postulated for several 'oral connotations'. For these relevant connotations the theoretical assumptions were proved empirically. However, there were no statistical differences between several groups of patients (those with an oral fixation and those with later fixations). Furthermore single dimensions of the semantic differential technique used, in contrast to the three-dimensional analysis, allowed the differentiation of patients with oral fixations from the others simply by using object representations that ought to be relevant for the oral stage of psychosexual development.

Arousal↗
PubMed2000

Experimental and empirical approaches in the study of aging.

Two approaches to the study of aging are contrasted. The results and implications of the gene-by-gene, hypothetico-deductive molecular genetic approach are compared with studies engendered by unique empirical findings. The former hypothesis-testing approach examines the changing phenotype that results from alterations of the genome and measures the relevance of a gene by the effectiveness with which it alters life-span. Investigations of empirical demographic and physiological puzzles that have come to light in aging studies, examine these phenomena for the broader understanding they bring rather than the knowledge of specific causative genetic elements. While the former hypothesis testing method requires caution in interpretation of results and conclusions, it has been highly informative. Studies of empirical phenomena have necessarily progressed more slowly, but have also yielded substantial gains. Both approaches have advanced the understanding of the aging process from distinctly different but complementary viewpoints.

Aging↗
PubMed2001

Criteria for patient decision making (in)competence: a review of and commentary on some empirical approaches.

The principle of autonomy presupposes Patient Decision Making Competence (PDMC). For a few decades a considerable amount of empirical research has been done into PDMC. In this contribution that research is explored. After a short exposition on four qualities involved in PDMC, different approaches to assess PDMC are distinguished, namely a negative and a positive one. In the negative approach the focus is on identifying psychopathologic conditions that impair sound decision making; the positive one attempts to assess whether a patient actually has the required abilities and qualities. Characteristic of the latter approach is the use of (or development of) test-like instruments for PDMC assessment. Some of these tests are discussed and commented on. Although they may be useful in investigating aspects of PDMC, none of the described approaches and tests offers a reliable and valid method for PDMC assessment. In response to a potential misuse of tests, the concept of a "supportive situation" is briefly introduced in order to draw attention to the risk of prematurely deeming patients incompetent on the basis of low test scores, whereas their insufficient performance may be (partly) attributable to a lack of situational support. Also, the need for and possibility of an emotionalist concept of PDMC are suggested, as an alternative to the more common rationalist one. In this regard, the legitimacy of competence being conceived as a presumption or fiction of law, deserves further investigation.

Cognition↗
PubMed1995

Rapid non-empirical approaches for estimating relative binding free energies.

Rapid non-empirical methods for estimating binding free energies are reviewed. A novel approach based on the application of the free energy perturbation formula to a biased ensemble is presented. Preliminary results demonstrating the applicability of this approach in protein systems are shown and the potential of this method in structure-based drug design is discussed.

Models, Theoretical↗
PubMed1986

Consistency of assessment of adverse drug reactions in psychiatric hospitals: a comparison of an algorithmic and an empirical approach.

Within an ongoing drug surveillance project (AMUP) in psychiatric hospitals, a comparative study was carried out to evaluate two methods commonly used in the field of adverse drug reaction assessment. Two raters, who have cooperated with the project since its inception, evaluated 80 randomly selected ADRs twice; first, by an empirical (implicit) approach, and second, 4 weeks later, by using an algorithm as proposed by Kramer et al. 1979. Agreement on medication and related probability ratings was obtained in 81% of all 80 cases for the empirical method (weighted Kappa = 0.41), and in 69% for the algorithmic method (weighted Kappa = 0.62), indicating that agreement exceeded chance for both methods. By comparison with assessments made in previous case conferences of the project, empirical ratings were found to be reliable over time due to homogeneous use of criteria by project raters. In contrast to the reports on the subject, agreement between raters appeared to be superior in the empirical method as compared to the algorithmic assessment. Analysis of disagreements suggested that probability ratings based on the empirical method were nonspecific, due to conventional criteria applied in the project. Inter-rater agreement was reduced by polypharmacy, especially in the case of algorithmic assessments. The consistency of assessment was also lowered by the fact that the 2 methods assigned different weights to particular assessment criteria.

Drug-Related Side Effects and Adverse Reactions↗
PubMed2006

A semi-empirical approach to projecting future sea-level rise.

A semi-empirical relation is presented that connects global sea-level rise to global mean surface temperature. It is proposed that, for time scales relevant to anthropogenic warming, the rate of sea-level rise is roughly proportional to the magnitude of warming above the temperatures of the pre-Industrial Age. This holds to good approximation for temperature and sea-level changes during the 20th century, with a proportionality constant of 3.4 millimeters/year per degrees C. When applied to future warming scenarios of the Intergovernmental Panel on Climate Change, this relationship results in a projected sea-level rise in 2100 of 0.5 to 1.4 meters above the 1990 level.

Journal Article↗
PubMed1996

The assessment of competence to make a treatment decision: an empirical approach.

OBJECTIVE: To compare physicians' judgements of competency in routine clinical practice with the findings obtained from a structured clinical interview. METHODS: Ninety-six patients referred for electroconvulsive therapy were administered the Competency Interview Schedule (CIS) prior to their first treatment. Cluster analysis was employed to categorize patients to 1 of 5 cluster centres represented by case studies previously judged competent or incompetent by lawyers and health professionals. RESULTS: A match-mismatch table revealed 88% (N = 66) of the 75 patients found competent by the attending physician and 90.5% (N = 19) of the 21 patients found incompetent by the attending physician were classified in agreement with the CIS. The 9 misclassified patients found competent by the attending physician but classified incompetent by the CIS had consented to treatment. The 2 misclassified patients found incompetent by the attending physician but classified competent by the CIS had refused treatment. Examination of individual item scores from the CIS indicated that, in some cases, a different standard of competency was applied in routine clinical practice depending upon the patient's treatment decision. CONCLUSIONS: The CIS is presented as a useful guide for clinicians with an interest in competency evaluations but caution is advised in using the instrument to make formal evaluations of competency owing to the imprecise definition of competency in various jurisdictions.

Adult↗
PubMed1997

New Semi-empirical Approach for the Calculation of 13C Chemical-Shift Tensors

The semi-empirical bond polarization theory is applied to the calculation of 13C chemical-shift tensors. This method allows prediction of shift tensors with deviations from experiment comparable to the errors of the ab initio methods. In contrast to ab initio calculations, a set of empirical parameters is needed, which can be estimated from experimental chemical-shift tensors solving a set of linear equations. The coefficients of this overdetermined set of equations are bond polarization energies that must be calculated within the framework of this theory. The parameters for C-C, C-H, and C-O bonds of sp3 and sp2 hybridized carbons and C-N bonds of sp3 carbons were obtained from 606 equations formed from experimental data from 20 substances taken from the literature. The substances include sugars, aromatic compounds, amino acids, and organic acids. The mean deviation of calculated from experimental 13C chemical-shift tensor components is 9 ppm.

Journal Article↗
PubMed1981

An empirical approach to insanity evaluations.

Described the development of the Rogers Criminal Responsibility Assessment Scales (RCRAS) as an empirically based testing procedure specifically designed for use in insanity evaluations. A pretest of the RCRAS that employed 10 case vignettes and a preliminary study of 25 patients are reported. Initial results indicated that the RCRAS has satisfactory interrater reliability and successfully discriminated between those patients evaluated as sane and insane. Results of the discriminant analysis, MANOVA, and factor analysis are discussed with reference to the RCRAS' construct validity and the need for further extensive studies.

Diagnosis, Differential↗
PubMed1998

A simplified empirical approach to evaluate the dissociation constant of a full agonist by the irreversible receptor inactivation method.

The estimation of the dissociation constant (Ka) of full agonists represents an essential tool for the classification of drugs and drug receptors, in functional pharmacology. The evaluation of the Ka was a problem until the development of the Furchgott's method (irreversible partial receptor inactivation method), which surely represents the most used analysis for the evaluation of the agonist Ka in experimental protocols on isolated tissues. The Furchgott's method can furnish a reliable estimation of the Ka, but it requires a relatively complicated manipulation of experimental data. In this article, an alternative approach for the evaluation of the Ka is proposed, on the basis of empirical considerations. This method, also based on the partial alkylation of a fraction of receptors, needs only the knowledge of the location parameters of the concentration-response curves and the application of a very simple equation, without any complicated intermediate interpolation of the experimental data.

Algorithms↗
PubMedDate not supplied

Malpractice litigation reform: empirical approaches to establishing the legal standard of care.

This article proposes that the legal standard of care in malpractice cases should be established through empirical methods rather than only with experts'subjective opinions. The authors outline and critique two approaches for doing so and explain the legal advantages and barriers to implementing these legal reforms. Basing the legal standard of care on evidence of actual physician behaviors and views would help to improve medical practice by reducing the need to engage in defensive medicine and by making it safer to institute quality improvement measures.

Data Collection↗
PubMed2000

An empirical approach to subtype identification in individuals with social phobia.

BACKGROUND: The present study used cluster analysis procedures to identify empirically subgroups of patients with social phobia in a large clinical sample. METHOD: The Liebowitz Social Anxiety Scale (LSAS) was administered to 382 patients from several studies of the treatment of social phobia. LSAS fear ratings were summed into four subscale scores (social interaction, public speaking, observation by others, eating and drinking in public) based on a previous factor analytical study of the LSAS. In order to produce a stable and robust solution, these factor scores were submitted to a two-stage clustering procedure consisting of an agglomerative-hierarchical clustering method followed by an iterative non-hierarchical clustering method. RESULTS: Three patient subgroups were identified based on their pattern of feared social situations on the LSAS. These groups were labelled: (1) pervasive social anxiety; (2) moderate social interaction anxiety; and (3) dominant public speaking anxiety. Clusters differed significantly on age and age of social phobia onset, as well as on measures of social anxiety, general anxiety and depressive symptomatology. Clusters also differed in the percentage of assigned patients who met criteria for the generalized subtype of social phobia and avoidant personality disorder. CONCLUSIONS: The results provide empirical support for the existence of three subgroups in a clinical sample of individuals with social phobia and contribute to the growing evidence for the heterogeneity of social phobia. Further study of the conceptual, clinical and aetiological significance of these subgroups is needed.

Adolescent↗
PubMed2005

An accurate and efficient empirical approach for calculating the dielectric self-energy and ion-ion pair potential in continuum models of biological ion channels.

This paper presents empirical formulas for calculating the dielectric self-energy and ion-ion pair interactions in cylindrical ion channels. The proposed approach can be extended to more complex channel structures, for example, (i) a "straight" channel with variable radius and (ii) a "curved" channel with constant radius. For calibration purposes, we compare results obtained based on the approximate effective potentials developed herein to exact electrostatic calculations obtained via the algorithm of Graf et al.: the agreement is satisfactory. A dynamic lattice Monte Carlo (DLMC) technique is used to further assess the accuracy and efficiency of the proposed empirical potentials. The concentration profiles and current-voltage curves produced with our simple empirical energy formulas are in excellent agreement with numerical results obtained using the algorithm of Graf et al., which calculates all relevant electrostatic forces exactly. The use of effective ion-ion potentials greatly reduces the computer memory required to perform DLMC ion permeation simulations in dielectrically inhomogeneous environments, thus enabling treatment of larger systems than can be handled by numerically exact techniques.

Algorithms↗
PubMed2006

An empirical approach for detecting nucleotide-binding sites on proteins.

Protein structure data in the PDB (Protein Data Bank) were used to construct empirical scores of nucleotide-protein interactions. A simple strategy to evaluate the spatial distribution of protein atoms around the base moieties of nucleotides was applied to categorize adenine, guanine, nicotinamide and flavin nucleotide-binding sites. In addition to the known nucleotide-binding motifs, the empirical scores detected several other features that were shared among proteins with different folds. The empirical scores were also used to predict the binding sites on protein molecules and a comprehensive test of the prediction system was performed. As a result, adenine, guanine, nicotinamide and flavin sites were detected with efficiencies of 31, 29, 32 and 40%, respectively. The predictions were judged to be successful if the predicted base with the best score was located within a 3.0 A r.m.s.d. from the known ligand positions.

Amino Acid Motifs↗
PubMed2005

Prediction of human drug clearance from in vitro and preclinical data using physiologically based and empirical approaches.

PURPOSE: The aim of this study is to compare the accuracy of five methods for predicting in vivo intrinsic clearance (CL(int)) and seven for predicting hepatic clearance (CL(h)) in humans using in vitro microsomal data and/or preclinical animal data. METHODS: The human CL(int) was predicted for 33 drugs by five methods that used either in vitro data with a physiologic scaling factor (SF), with an empirical SF, with the physiologic and drug-specific (the ratio of in vivo and in vitro CL(int) in rats) SFs, or rat CL(int) directly and with allometric scaling. Using the estimated CL(int), the CL(h) in humans was calculated according to the well-stirred liver model. The CL(h) was also predicted using additional two methods: using direct allometric scaling or drug-specific SF and allometry. RESULTS: Using in vitro human microsomal data with a physiologic SF resulted in consistent underestimation of both CL(int) and CL(h). This bias was reduced by using either an empirical SF, a drug-specific SF, or allometry. However, for allometry, there was a substantial decrease in precision. For drug-specific SF, bias was less reduced, precision was similar to an empirical SF. Both CL(int) and CL(h) were best predicted using in vitro human microsomal data with empirical SF. Use of larger data set of 52 drugs with the well-stirred liver model resulted in a best-fit empirical SF that is 9-fold increase on the physiologic SF. CONCLUSIONS: Overall, the empirical SF method and the drug-specific SF method appear to be the best methods; they show lower bias than the physiologic SF and better precision than allometric approaches. The use of in vitro human microsomal data with an empirical SF may be preferable, as it does not require extra information from a preclinical study.

Animals↗
PubMed2000

The implication of selection bias in clinical studies of late life depression: an empirical approach.

OBJECTIVES: It is supposed that selection bias precludes the extrapolation of results of studies carried out in a clinical setting to the general population. There is little empirical evidence demonstrating the degree to which those depressed in the community are different from those treated in clinical settings. This study compared elderly patients with major depression admitted to a psychiatric hospital with those living in the community. METHODS: All elderly (55 years and older) patients admitted between 1990 and 1992 to a psychiatric hospital with DSM major depression as the primary diagnosis (n=104), were compared with all elderly patients with the same diagnosis (n=59) who were participating in a large community study (Longitudinal Aging Study, Amsterdam). Data were gathered from the clinical sample using chart-reviews while the community-based sample was interviewed. The two groups were compared with respect to differences in demographic variables, presenting symptoms, risk factors and treatment. RESULTS: The following characteristics were significantly more prevalent in the clinical sample: late onset of the depression, threat of suicide, conflicts with significant others and use of antidepressant medication. Chronic physical illness was the only characteristic that was more prevalent in the community sample. CONCLUSION: The results confirm that elderly patients treated in clinical psychiatry represent a group with more threatening and more disruptive depressive illness. Major depression in the community was more often associated with chronic physical illness, which may hamper the recognition and treatment of depression. As the two samples were similar in all other respects, selection bias, hampering comparison of results of studies carried out across treatment settings, appears to have a very limited effect.

Activities of Daily Living↗