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At least 163 records · Page 9Linked to original sources
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↗
PubMed1989

Radiotherapy or surgery for T2N0M0 glottic carcinoma? A decision-analytic approach.

Decision analysis was used to evaluate the results of treatment of T2N0M0 glottic carcinoma as presented in the literature. Based on mean values for recurrence, salvage eligibility after recurrence and salvage success, the 5-year survival after radiotherapy and surgery proved to be almost identical, 85 and 86%. If the recurrence rates and the salvage rates were varied, a marginal advantage for surgery in small tumours (T2a) and a major advantage in more extended (T2b) tumours was seen if only survival is considered. To take the quality of speech into account, a utility analysis was performed. A utility scale was defined ranging from 0.0 as the value for death, to 1.0 for a successfully irradiated patient with preservation of normal speech. A utility of 0.99 or less for the laryngectomized patient would favour radiotherapy over surgery for all T2 tumours. In patients with T2b tumours and in extreme circumstances, e.g. if failure rates of radiotherapy are extremely high or if recurrence rates after surgery are extremely low, an exact assessment of patient utilities may be pivotal. Under normal circumstances radiotherapy is preferred for T2N0M0 glottic carcinoma if both survival and the quality of speech are taken into account.

Carcinoma↗
PubMed1993

Analytical approaches to genomic evolution.

We model the non-local mechanisms of genomic evolution and propose methods for studying the evolutionary divergence of species based on these models. Mechanisms include the movement of segments of genomes within a single chromosome (transpositions), the reciprocal translocation of segments between two chromosomes, and the inversion of segments. Each of these is studied in the context of a different type of genomic data. We introduce the theory of phylogenetic invariants for evolutionary inference based on very long macromolecular sequences.

Animals↗
PubMed1983

Assessing adolescent health needs: a factor analytic approach.

Advances in technology are rapidly expanding health educators' resources for presenting information tailored to meet individual health needs and interests. A self-administered questionnaire was given to 510 youths in grades 6 through 9 to ascertain adolescents' health concerns and thus develop more appropriate educational programs. Smoking, diet and weight control, physical fitness, and general health items were included. Factor analysis methods identified ten concerns; smoking, weight control, exercise effects, peer approval of appearance, preparatory health behaviors, planning and maintaining a personal health program, feeling good about oneself, communication issues, comparisons with others, and resistance to negative peer influences. Sex and grade were significantly associated with particular responses. Recommendations include the value of addressing each area of the content domain as it relates to health lessons to ensure that information is relevant to the needs and interests of individual adolescents.

Adolescent↗
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↗
PubMed1996

A functional-analytic approach to the diagnosis of a transient tic disorder.

The diagnostic utility of functional analyses has been demonstrated with a variety of behaviors including tics. Whereas previous analyses have focused on the discovery of maintaining variables to aid in treatment prescription, we employed a functional analysis to confirm a clinical diagnosis. An 11 year old male student, who had not been previously diagnosed with a tic disorder, exhibited multiple vocal tic-like behaviors which had persisted over a period of time. Teacher reports conflicted regarding the possible etiology of these behaviors. Hence, a functional analysis was conducted in the classroom to determine if the behaviors were maintained by operant variables. Our hypothesis stated that the occurrence of vocal behaviors across experimental conditions would strongly indicate the presence of a tic disorder. The functional analysis included the following conditions: attention, escape, alone, freeplay, and high sensory stimulation. We used a multi-element design to evaluate the effects of the different stimulus conditions on vocal-behavior frequency. Data indicated the student exhibited vocal behaviors in all conditions. However, the behaviors were partially exacerbated in the attention and escape conditions. Results supported the diagnosis of a transient tic disorder affected by operant variables.

Attention↗
PubMed2002

Functional motions of influenza virus hemagglutinin: a structure-based analytical approach.

Influenza virus hemagglutinin (HA), a homotrimeric integral membrane glycoprotein essential for viral infection, is engaged in two biological functions: recognition of target cells' receptor proteins and fusion of viral and endosomal membranes, both requiring substantial conformational flexibility from the part of the glycoprotein. The different modes of collective motions underlying the functional mobility/adaptability of the protein are determined in the present study using an extension of the Gaussian network model (GNM) to treat concerted anisotropic motions. We determine the molecular mechanisms that may underlie HA function, along with the structural regions or residues whose mutations are expected to impede function. Good agreement between theoretically predicted fluctuations of individual residues and corresponding x-ray crystallographic temperature factors is found, which lends support to the GNM elucidation of the conformational dynamics of HA by focusing upon a subset of dominant modes. The lowest frequency mode indicates a global torsion of the HA trimer about its longitudinal axis, accompanied by a substantial mobility at the viral membrane connection. This mode is proposed to constitute the dominant molecular mechanism for the translocation and aggregation of HAs, and for the opening and dilation of the fusion pore. The second and third collective modes indicate a global bending, allowing for a large lateral surface exposure, which is likely to facilitate the close association of the viral and endosomal membranes before pore opening. The analysis of kinetically hot residues, in contrast, reveals a localization of energy centered around the HA2 residue Asp112, which apparently triggers the solvent exposure of the fusion peptide.

Anisotropy↗
PubMed2001

Analytical approaches to measuring cospeciation of host and parasites: through a glass, darkly.

Studies of cophylogenetic associations between hosts and parasites have become increasingly common. Historically, congruence between host and parasite phylogenies has been seen as evidence for cospeciation. Analyses of such coevolutionary relationships, however, are made extremely difficult by the complex interplay of cospeciation, host switching, sorting (extinction), duplication (intrahost speciation) and inertia (lack of parasite speciation) events, all of which may produce incongruence between host and parasite phylogenies. Here we review several methods of analysing cospeciation. We illustrate these methods with an example from a Procellariiformes (seabird) and chewing louse (Halipeurus) association.

Animals↗
PubMed2001

Relationship between worm burden and male proportion in Schistosoma mansoni experimentally infected rodents and primates. A meta-analytical approach.

This paper investigates the relationship between the worm burden and the male proportion of adult Schistosoma mansoni. This relationship was tested using data from the literature on S. mansoni experimentally infected rodents and primates. The analyses were performed within each animal model (rat, mouse, hamster and monkey) and showed positive linear relationships between worm burden and male proportion. An analysis between the four animal models showed the same positive linear relationship. The role of the genetic diversity of male and female schistosomes in this relationship is discussed.

Animals↗
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↗
PubMed2000

Unveiling synaptic plasticity: a new graphical and analytical approach.

Short-term synaptic plasticity has a key role in information processing in the CNS, whereas memories can be formed through long-lasting changes in synaptic strength. Despite the importance of these phenomena, it remains difficult to determine whether a synaptic modulation is expressed at a presynaptic or postsynaptic site. This article describes a new approach that, in its simplest form, can identify the site of expression by direct graphical means. A more-sophisticated form of the technique can quantify functional synaptic properties and determine which of these properties is altered following a modulation of synaptic strength.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed2000

An analytical approach to the implementation of genetically modified crops.

Public scepticism towards genetically modified (GM) crops is increasing. To address this, the risks and benefits of GM crops must be examined across scientific disciplines, and be discussed with the authorities, the agricultural industry and the consumers. In a feasibility study we have systematically analysed the challenges of the development and marketing of GM crops in Europe. A life-cycle inventory was used together with established technology foresight techniques in an interdisciplinary and empirical framework. The approach taken in this study established a dialogue between stakeholders and provided a framework for discussions about the future direction of GM crops.

Agriculture↗