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Results for “environmental variability”

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At least 631 records · Page 35Linked to original sources
PubMed2007

Organizational and unit factors contributing to reduction in the use of seclusion and restraint procedures on an acute psychiatric inpatient unit.

OBJECTIVE: The use of seclusion or restraint (S/R) as an emergency medical intervention to assist patients in regaining behavioral control continues to be an area of interest and concern for the Joint Commission on the Accreditation of Healthcare Organizations (JCAHO), consistent with the ongoing concerns in the medical, patient advocate, legislative and legal communities. This study examined unit characteristics and the use of S/R in a VA facility with a secured, acute mental health unit before and after the promulgation of the JCAHO 2000 standards for utilization of S/R for behavioral health reasons. METHODS: Variables examined include patient acuity, patient census, number of admits, number of discharges, length of stay, number of nursing staff on duty, critical incidents and S/R hours per month. RESULTS: Results indicated S/R use began showing a notable decrease corresponding to the time that senior unit management began discussions of the new JCAHO standards. These reductions maintained statistical significance even after controlling for changes in unit environmental variables.

Acute Disease↗
PubMed1991

A didactic computer simulation of the environmental impact of a pollution discharge.

Algorithms for simulating the response of a benthic animal community and several abiotic environmental variables to organic pollution are described. An IBM PC compatible computer program incorporating these methods has been written. The program simulates the abundance response of 23 species, the redox potential depth profile and several other sediment variables at any distance from a point source of pollution. The program has been designed as a teaching tool and examples of its use to study pollution biology and biometrics are given.

Algorithms↗
PubMed1983

Factors affecting the irreversible attachment of Pseudomonas aeruginosa to stainless steel.

To better understand the interaction between bacteria and surfaces, we studied the irreversible attachment of Pseudomonas aeruginosa to a common surfacing material. When brought into contact with the steel, cells began to attach in less than 1 min and the number adhering increased with time. An important physiological variable in attachment was cell motility since adherence decreased at least 90% when flagella were removed by blending. This treatment was shown to be effective because it caused motility loss and not because it removed a structure necessary for adherence. Cell viability was less important since adherence decreased only 50% when the number of viable cells was reduced 4.7 logs by heating or formaldehyde treatment. Significant environmental variables included turbulence and ionic strength. Attachment of motile cells was reduced 90% by agitation, although agitation had little effect on adherence of nonmotile cells. Both motile and nonmotile cells adhered poorly in distilled water with attachment increasing as CaCl2 or NaCl concentration increased to 10 mM. At 100 mM, attachment decreased. Viable cells, both motile and nonmotile, adhered best at a pH of 7 to 8, whereas nonviable cells attached most rapidly at a low pH.

Adhesiveness↗
PubMed1994

Genetic variation of broiler feed consumption and efficiency corrected for differences in test body weights.

Feed consumption and feed efficiency data obtained over nine generations from three selected strains of broilers were adjusted for differences in either initial or initial and final test BW (at 28 and 42 d, respectively). Genetic and environmental variables were estimated for each strain using an animal model with restricted maximum likelihood procedures to avoid bias due to reduced genetic variation caused by selection. Variance component and heritability estimates before and after adjustment of these traits for differences in test weights were evaluated. Adjustments of feed consumption data for either initial test BW or both initial and final test BW reduced additive genetic and environmental variation. Reductions were relatively greater for additive genetic than for environmental variance, thereby reducing the heritability of the adjusted trait. Adjustment of feed efficiency for initial test BW altered additive genetic variation little and reduced environmental variation slightly; however, correction for both test BW reduced variation of both components. Heritability of adjusted feed efficiency was 40% larger (.33 to .35 vs .21 to .28) than for uncorrected feed efficiency, but phenotypic variation of the adjusted feed efficiency was reduced 42% (5.82 to 6.13 vs 10.30 to 11.35). Heritabilities of feed consumption and efficiency were essentially the same (.34 and .36) after adjustment for both test weights. Changes in genetic and environmental variation and heritability due to adjustments were similar for the three strains.

Animals↗
PubMed2005

Carbon dioxide fluxes in a spatially and temporally heterogeneous temperate grassland.

Landscape position, grazing, and seasonal variation in precipitation and temperature create spatial and temporal variability in soil processes, and plant biomass and composition in grasslands. However, it is unclear how this variation in plant and soil properties affects carbon dioxide (CO2) fluxes. The aim of this study is to explore the effect of grazing, topographic position, and seasonal variation in soil moisture and temperature on plant assimilation, shoot and soil respiration, and net ecosystem CO2 exchange (NEE). Carbon dioxide fluxes, vegetation, and environmental variables were measured once a month inside and outside long-term ungulate exclosures in hilltop (dry) to slope bottom (mesic) grassland throughout the 2004 growing season in Yellowstone National Park. There was no difference in vegetation properties and CO2 fluxes between the grazed and the ungrazed sites. The spatial and temporal variability in CO2 fluxes were related to differences in aboveground biomass and total shoot nitrogen content, which were both related to variability in soil moisture. All sites were CO2 sinks (NEE>0) for all our measurements taken throughout the growing season; but CO2 fluxes were four- to fivefold higher at sites supporting the most aboveground biomass located at slope bottoms, compared to the sites with low biomass located at hilltops or slopes. The dry sites assimilated more CO2 per gram aboveground biomass and stored proportionally more of the gross-assimilated CO2 in the soil, compared to wet sites. These results indicate large spatio-temporal variability of CO2 fluxes and suggest factors that control the variability in Yellowstone National Park.

Carbon Dioxide↗
PubMed2000

Guideline implementation: what the literature doesn't tell us.

BACKGROUND: Despite large numbers of studies and literature reviews about guideline implementation, it remains unclear whether and how clinical guidelines can be used to improve the quality of medical care. This study sought to learn whether these studies and reviews have recognized the importance of systems thinking and organizational change for implementation. METHODS: A literature search was conducted for systematic reviews of guideline implementation or practice improvement studies. Each review was studied for the extent to which it identified or discussed the value of systems changes, organizational support, practice environmental factors, and use of a change process. RESULTS: Forty-seven good-quality systematic reviews were found. They largely concurred that using reminders and perhaps using feedback in the course of clinical encounters were the most effective ways of implementing guidelines. However, these same reviews rarely identified these strategies as systems changes, and there was little discussion about any need for organizational support or attention to various environmental variables that might affect implementation. The change process required to introduce a new or changed practice system received even less attention. CONCLUSION: Reviews of guideline implementation trials have focused on how to change the behavior of individual clinicians. There has been little attention to the impact of practice systems or organizational support of clinician behavior, the process by which change is produced, or the role of the practice environmental context within which change is being attempted. New attention to these issues may help us to better understand and undertake the process of improving medical care delivery.

Bibliometrics↗
PubMed2001

Zooplankton assemblages and biomass during a 4-period survey in a northern Mediterranean coastal lagoon.

The authors proposed to examine zooplankton biomass at three stations inside (T and Z) and outside (M) a coastal lagoon of the north-western Mediterranean Sea. Station T represented the lagoon central area, and station Z was positioned in a shellfish farming sector, while the seaside station (M) served as a reference of marine environment. Analyses were designed to outline the net zooplankton assemblages (taxonomic structures and length distributions) in different environmental conditions, including the farming activity. A discriminant analysis of environmental variables determined that temperature, salinity and phytoplankton implied mainly in spatial pattern of the samples. An ordination of taxa biomasses showed two main factors which might contribute to the organisation of the zooplankton assemblages: the geographical position and the thermal period. The geographical position integrated the lagoon-sea water exchange under forcing parameters (habitat, tides and winds). The thermal period reflected both the populations development cycles and the environmental constraints (temperature, salinity, trophic resources). The resulting effects appeared in structured zooplankton assemblages in space and time. The number of 50 microns interval length classes and of taxa decreased from the seaside and the lagoon central area free of farming activity to the shallower farming zone. But the biomass-length distribution profiles did not closely follow such an expected opposition between opened and confined areas: more extended profiles were observed at station Z. Biomass dominant size classes concerned the range up to 300 microns. This size category appeared to collapse in terms of biomass from the seaside or central area of the lagoon towards the farming area, similarly to zooplankton global biomass fluctuations. Difference between biomass levels and between biomass structures suggested that net zooplankton partly acted as food competitors of macro-filtering organisms, and as preys for farming shellfish and associated epifauna. This impact mainly concerned microzooplankton populations.

Animals↗
PubMed2005

Landscape genetics of the blotched tiger salamander (Ambystoma tigrinum melanostictum).

The field of landscape genetics has great potential to identify habitat features that influence population genetic structure. To identify landscape correlates of genetic differentiation in a quantitative fashion, we developed a novel approach using geographical information systems analysis. We present data on blotched tiger salamanders (Ambystoma tigrinum melanostictum) from 10 sites across the northern range of Yellowstone National Park in Montana and Wyoming, USA. We used eight microsatellite loci to analyse population genetic structure. We tested whether landscape variables, including topographical distance, elevation, wetland likelihood, cover type and number of river and stream crossings, were correlated with genetic subdivision (F(ST)). We then compared five hypothetical dispersal routes with a straight-line distance model using two approaches: (i) partial Mantel tests using Akaike's information criterion scores to evaluate model robustness and (ii) the BIOENV procedure, which uses a Spearman rank correlation to determine the combination of environmental variables that best fits the genetic data. Overall, gene flow appears highly restricted among sites, with a global F(ST) of 0.24. While there is a significant isolation-by-distance pattern, incorporating landscape variables substantially improved the fit of the model (from an r2 of 0.3 to 0.8) explaining genetic differentiation. It appears that gene flow follows a straight-line topographic route, with river crossings and open shrub habitat correlated with lower F(ST) and thus, decreased differentiation, while distance and elevation difference appear to increase differentiation. This study demonstrates a general approach that can be used to determine the influence of landscape variables on population genetic structure.

Animals↗
PubMed1993

Embryonic growth inhibition induced by cocaine is associated with the suppression of ornithine decarboxylase activity.

Cocaine use during pregnancy results in significant increases in fetal morbidity and mortality. Multiple maternal and environmental variables influence the fetal response to cocaine, and growth suppression of the developing child is frequently associated with in utero cocaine exposure. Using intact chick embryos as well as cultured embryonic tissue as a model, we report that the growth suppression induced by cocaine exposure is correlated with molecular changes occurring directly in the embryonic cells and that these molecular changes appear to be distinct from other maternal, placental, or environmental effects of the drug, including anoxia. Specifically, embryonic cocaine exposure suppresses the normal developmental increase in ornithine decarboxylase (ODC) enzymatic activity. The loss of ODC activity during the early stages of development is dose dependent and is correlated with the degree of growth suppression. The cocaine-induced loss of decarboxylase activity is specific to ODC, but cocaine, per se, has no effect on ODC activity in vitro. Moreover, a single dose of exogenous putrescine given at 120 hr of incubation blocks the cocaine-induced growth suppression. In cultured embryonic tissue, cocaine exposure inhibits the ability of a known trophic factor (insulin) to induce growth and also blocks the associated increase in ODC activity. Preliminary data suggest that cocaine hinders the binding of insulin to embryonic cells. Because ODC is a focal enzyme for the regulation of growth, the data suggest that cocaine-induced changes in the mitogenic induction of embryonic/fetal ODC activity may be a part of the biochemical mechanism by which cocaine-induced growth inhibition occurs.

Animals↗
PubMed1995

[Evaluation of the psychosocial care in maternity: experience at the Poitiers University Hospital].

BACKGROUND: High psychosocial risk pregnancies require specialized multidisciplinary help and follow-up in order to improve the outcome of babies. POPULATION AND METHODS: Thirty pregnancies were selected among 3500 and followed by a multidisciplinary team during 1990 and 1991. Evaluation included risk predictors, neurodevelopmental outcome of children at 9 and 24 months, number and time of judicial notifications. Evaluation of the mother-to-baby relationship by a psychologist as well as the environmental variables were performed. RESULTS: Four families had one or two, 20 families three or five and six families, six or more of the 15 risk predictors studied. Over the babies followed-up until the age of 24 months, four were placed out of the family, three hospitalizations were medically unjustified and there was no hospitalization for child abuse or neglect. Twelve children had development delay and two developed an environmental-related staturo-ponderal delay. Judicial notifications were realized 18 times during pregnancy or just after delivery and six times during the follow-up for child abuse and neglect. CONCLUSIONS: Taking care of high psychosocial risk pregnancies could be improved in special hospitalization units for mother and child. A better awareness of this problem could also improve the outcome of children, which remains very alarming.

Adolescent↗
PubMedDate not supplied

Combining pathway analysis with flux balance analysis for the comprehensive study of metabolic systems.

The elucidation of organism-scale metabolic networks necessitates the development of integrative methods to analyze and interpret the systemic properties of cellular metabolism. A shift in emphasis from single metabolic reactions to systemically defined pathways is one consequence of such an integrative analysis of metabolic systems. The constraints of systemic stoichiometry, and limited thermodynamics have led to the definition of the flux space within the context of convex analysis. The flux space of the metabolic system, containing all allowable flux distributions, is constrained to a convex polyhedral cone in a high-dimensional space. From metabolic pathway analysis, the edges of the high-dimensional flux cone are vectors that correspond to systemically defined "extreme pathways" spanning the capabilities of the system. The addition of maximum flux capacities of individual metabolic reactions serves to further constrain the flux space and has led to the development of flux balance analysis using linear optimization to calculate optimal flux distributions. Here we provide the precise theoretical connections between pathway analysis and flux balance analysis allowing for their combined application to study integrated metabolic function. Shifts in metabolic behavior are calculated using linear optimization and are then interpreted using the extreme pathways to demonstrate the concept of pathway utilization. Changes to the reaction network, such as the removal of a reaction, can lead to the generation of suboptimal phenotypes that can be directly attributed to the loss of pathway function and capabilities. Optimal growth phenotypes are calculated as a function of environmental variables, such as the availability of substrate and oxygen, leading to the definition of phenotypic phase planes. It is illustrated how optimality properties of the computed flux distributions can be interpreted in terms of the extreme pathways. Together these developments are applied to an example network and to core metabolism of Escherichia coli demonstrating the connections between the extreme pathways, optimal flux distributions, and phenotypic phase planes. The consequences of changing environmental and internal conditions of the network are examined for growth on glucose and succinate in the face of a variety of gene deletions. The convergence of the calculation of optimal phenotypes through linear programming and the definition of extreme pathways establishes a different perspective for the understanding of how a defined metabolic network is best used under different environmental and internal conditions or, in other words, a pathway basis for the interpretation of the metabolic reaction norm.

Glucose↗
PubMed1976

Plasma protein variability in MZ twins.

A previous study had shown that only MZ twins are easily exchanged by trained police dogs. This is certainly due to the superimposability of the biochemical basis of body scent. A different approach has now been tried, based on plasma protein fractionating procedures. A pilot study has shown that PolyAcrilamide Gel Electrophoresis (PAGE) results, as expected, in widely different patterns only in DZ twin pairs. Plasma specimens from a sample of 55 supposedly MZ twin pairs were analysed by PAGE. The substantial superimposability of MZ cotwin patterns was confirmed. Analysis of the different fractions indicates the extent of environmental variability. Application to zygosity determination is suggested.

Blood Proteins↗
PubMed1990

Medical students' attitudes toward AIDS, homosexual, and intravenous drug-abusing patients: a re-evaluation in New York City.

After completing their clinical rotations, 69% of the third-year medical school class at Columbia University responded to a survey based on one originally used by Kelly et al. at the University of Mississippi, to determine their attitudes toward acquired immunodeficiency syndrome (AIDS) patients, homosexual men, and intravenous drug abusers (IVDAs). Results of this study were compared to the findings of Kelly et al. to determine how, if at all, geographic and environmental exposures affected student attitudes. Unlike the University of Mississippi students, who exhibited a highly negative and prejudiced view of homosexuals and patients with AIDS, Columbia students displayed no evidence of negative attitude toward homosexuals and a much less harsh judgment of AIDS patients. They, however, did have dramatically negative attitudes toward IVDAs; 78.4% stated that they strongly disliked and would avoid this group of patients. There is a complex multi-variable environmental effect on students' attitudes during medical school. It is not possible to generalize attitudes from one medical school to another. The necessity of incorporating activities into student education to evaluate and to reduce prejudice is discussed.

Acquired Immunodeficiency Syndrome↗
PubMed2001

Genetic contribution to the variance in left ventricular mass: the Tecumseh Offspring Study.

OBJECTIVE: To estimate the contribution of heredity to the variance in left ventricular mass (LVM), and to ascertain whether genetic factors may interact with non-genetic factors in promoting LVM growth. SUBJECTS AND SETTING: The study population consisted of 290 healthy parents and 251 healthy children living in Tecumseh, Michigan, USA. MAIN OUTCOME MEASURE: Correlation of parents' LVM with offspring's LVM adjusting for a number of clinical variables. METHODS: LVM in parents and offspring was measured with M-mode echocardiography by the same investigators. RESULTS: Parents unadjusted LVM was unrelated to offspring unadjusted LVM, but after removing the confounding effect of age, sex, anthropometric measurements, systolic blood pressure, plasma insulin and urinary sodium excretion, parent-child correlation for LVM was 0.28 (P = 0.006). The relative contribution of parental-adjusted LVM and of several offspring phenotypic and environmental variables on offspring LVM was evaluated by multivariable regression analysis. When age, gender, anthropometric measurements and systolic blood pressure were accounted for, adjusted LVM of parents explained only 1.6% of the total variance in offspring LVM. However, after inclusion of insulin and urinary sodium in the model heredity explained 7.6% of the total variance in offspring LVM, and its predictive power was second only to that of child's height. Furthermore, an interactive effect of parental LVM with offspring systolic blood pressure was found on child's left ventricular mass. CONCLUSION: Heredity can explain a small, but definite proportion of the variance in LVM. Higher blood pressure favors the phenotypic expression of the genes that regulate LVM growth.

Adolescent↗
PubMed1985

Who goes and who stays: subject loss in a multicenter, longitudinal follow-up study.

Subject loss in a cohort of 645 infants and their families, enrolled in a multicenter clinical trial, was described. Medical/biologic, socioeconomic and social support (Environmental Quality Index [EQI] composite), and developmental outcome data were obtained. Dropout was evaluated by comparing infants who withdrew at any time throughout the study to those who remained, as well as at four different time periods between 40 weeks conceptional age and 36 months. A dropout profile was also developed. Overall dropout was predicted by EQI score, clinical center, gestational age category, and 18-month developmental status. In addition to these variables, the dropout profile included race, but not 18-month developmental status. Medical/biologic variables, environmental quality, and race and center were most influential in the first, second and third, and fourth time periods, respectively. The identification of factors which are associated with increased subject loss can help researchers project needed sample sizes in future studies.

Black or African American↗
PubMed1994

The Children's Headache Assessment Scale (CHAS): factor structure and psychometric properties.

This study investigated the content validity, factor structure, and psychometric properties of the Children's Headache Assessment Scale (CHAS), a parent rating scale for identifying environmental variables associated with pediatric headache. In Study 1, input from physicians and psychologists was obtained to develop a revised set of 44 items receiving high endorsement. In Study 2, the questionnaire was administered to parents of 92 child headache sufferers, ages 6-16, and readministered 2 weeks later. An exploratory factor analysis revealed five factors (Disruptive Impact, Social Consequences, Stress Antecedents, Physical Antecedents and Quiet Coping, and Prescription Medication Use) that reflect distinct environmental concomitants of childhood headache. Scale reliabilities (alpha, .64-.82) indicate acceptable internal consistency, and test-retest reliabilities indicate relatively stable factors and items. High scores on the Disruptive Impact factor were associated with more severe, lengthy, and infrequent headache occurrence, lending initial support for the validity of this factor. Overall, the findings support the clinical and research utility of the CHAS in behavioral treatment of childhood headache.

Adolescent↗
PubMed2006

The use of time-series data in the assessment of macrobenthic community change after the cessation of sewage-sludge disposal in Liverpool Bay (UK).

Sewage sludge was disposed of in Liverpool Bay for over 100 years. Annual amounts increased from 0.5 million tonnes per annum in 1900 to approximately 2 million tonnes per annum by 1995. Macrofauna and a suite of environmental variables were collected at a station adjacent to, and a reference station distant from, the disposal site over 13 years, spanning a pre- (1990-1998) and post- (1999-2003) cessation period. Univariate and multivariate analyses of the time-series data showed significant community differences between reference and disposal site stations and multivariate analyses revealed station-specific community development post-disposal. Temporal variability of communities collected at the disposal station post-cessation was higher than during years of disposal, when temporally stable dominance patterns of disturbance-tolerant species had established. Alterations of community structure post-disturbance reflected successional changes possibly driven by facilitation. Subtle faunistic changes at the Liverpool Bay disposal site indicate that the near-field effects of the disposal of sewage sludge were small and therefore could be considered environmentally acceptable.

Analysis of Variance↗
PubMed1978

Activities of types A and B MAO and catechol-o-methyltransferase in blood cells and skin fibroblasts of normal and chronic schizophrenic subjects.

We assayed activities of monoamine oxidase (MAO) type B in blood platelets and type A (and B) in fibroblasts cultured from punch biopsy specimens of skin, as well as of catechol-O-methyltransferase (COMT) in erythrocytes and fibroblasts. Fibroblasts contained moderate amounts of both forms of MAO (types A and B) found in human brain and large amounts of COMT activity. Activities of both enzymes correlated poorly between fibroblasts and blood cells. Comparing carefully diagnosed chronic schizophrenics with age-matched normal young men, we found no difference in these biochemical variables, nor could we distinguish patients with paranoid symptoms. In contrast, we confirmed markedly lower MAO activities in platelet samples from chronic patients provided by colleagues at the National Institute of Mental Health. Results concerning MAO and COMT activities are now sufficiently inconsistently characteristic of schizophrenics as to question their clinical applicability and to indicate a need for further critical evaluation, with special attention to diagnosis, matching of subjects, and effects of possible spurious environmental variables.

Adolescent↗