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PubMed2004

Assessment of phytoplankton density in relation to environmental variables in Gopalaswamy pond at Chitradurga, Karnataka.

Surface water samples of the Gopalaswamy pond were studied at two different sites during September 1997 to January 1998 and phytoplanktons were studied in relation to ten environmental variables during this period. A total of 30 species of phytoplanktons were identified under four classes, Chlorophyceae, Cyanophyceae, Bacillariophyceae and Euglenophyceae. Among these, maximum density was recorded under Cyanophyceae, Chlorophyceae, Cyanophyceae and Bacillariophyceae showed considerable fluctuations with environmental variables.

Animals↗
PubMed2001

A model for forecasting emergency hospital admissions: effect of environmental variables.

This study modeled patterns and trends in emergency hospital admissions at a hospital in Madrid, Spain. The purpose was to quantify qualitative associations that have been detected between such admissions and a number of environmental variables. The following data were used: unscheduled daily emergency hospital admissions, Madrid air pollution data, and meteorological data. Time-series analysis was performed, with Box-Jenkins modeling. A multivariate model was constructed, incorporating the different causes of admissions and the respective environmental variables. Statistically significant associations were found between hospital admissions and other variables, indicating relationships with temperature, relative humidity, and mean daily tropospheric ozone concentrations. Whereas the effect of heat on admissions was short term, that of cold was in evidence from the second week. The association with ozone showed a seven-day lag and basically manifested itself as an influence on admissions for circulatory disease.

Cardiovascular Diseases↗
PubMed2006

Seroepidemiology and occupational and environmental variables for leptospirosis, brucellosis and toxoplasmosis in slaughterhouse workers in the Paraná State, Brazil.

Leptospirosis, brucellosis and toxoplasmosis are widely-distributed zoonosis, being the man an accidental participant of their epidemiological chains. The aim of this paper was to make a seroepidemiological report and identify occupational and environmental variables related to these illnesses in 150 workers in a slaughterhouse in the Northern region of Paraná. For the diagnosis of leptospirosis a microscopical seroagglutination test was applied; for brucellosis, the tamponated acidified antigen test and the 2-mercaptoetanol tests were used, and for toxoplasmosis the indirect immunofluorescence reaction test. For each employee an epidemiological survey was filled, which investigated occupational and environmental variables which could be associated with these infections. Positive results for leptospirosis were found in 4.00% of the samples, for brucellosis in 0.66% of samples and toxoplasmosis in 70.00%. From the three diseases researched, only the results for leptospirosis suggest occupational infection.

Abattoirs↗
PubMed1993

Analysis of behavior state conditions and associated environmental variables among students with profound handicaps.

State conditions in combination with environmental events and factors significantly affect the level of alertness and responsiveness among students with profound and multiple handicaps. State conditions and environmental variables over a continuous, 5-hour period for each of 25 students in classroom settings were measured. Data were assessed using transitional probability, time series, and correspondence analysis procedures. Results showed the presence of state sequence patterns, short state change periods, and a relatively small amount of association between specific behavior states and the environmental factors and events measured in the study.

Adolescent↗
PubMed1983

Gastrointestinal cancer mortality in New Jersey counties, and the relationship with environmental variables.

The State of New Jersey (NJ) USA has been thought to have an unusually high cancer mortality rate; this assumption has been based on 1950-1969 mortality data for its 21 counties. This paper presents an analysis of gastrointestinal (GI) cancer mortality rates in New Jersey counties during 1968-1977, a comparison with the 1950-1969 rates, and associations between current GI cancer mortality rates and selected environmental variables. Age-adjusted mortality rates for GI cancers were calculated for the 21 NJ counties during the period 1968-1977, and were compared with the period 1950-1969, with the Surveillance, Epidemiology and End Results (SEER) survey and with cancer mortality in the US, 1973-1977. The county rates were also correlated with: the distribution of chemical toxic waste disposal sites; annual per capita income; the rates of low birth weight, birth defects, and infant mortality; chemical industry distribution; percentage of the population employed in chemical industries; the density of population; and the urbanization index for each of the counties. Some of the major findings are: Age-adjusted GI cancer mortality rates (all sites combined) were higher than national rates in 20 of 21 NJ counties. In comparison with national trends, NJ stomach cancer rates have declined less, oesophageal cancer rates have declined more, and pancreatic cancer mortality rates have followed similar patterns. Cancer mortality rates in NJ during the period 1968-1977 significantly (p less than 0.0001) exceeded national rates for cancer of the oesophagus (white male, non-white male), stomach (men and women), colon (white male, white female, non-white female), and rectum (whites only). In 18 of the 21 NJ counties, the observed number of cancer deaths for at least one GI cancer site was significantly greater than expected at the 0.0001 level for at least one population subgroup. Among white men, a significant (p less than 0.0001) excess of observed over expected cancer deaths was observed for three or more GI cancer sites in seven counties. The environmental variables that were most frequently associated with GI cancer mortality rates (except pancreatic cancer) were degree of urbanization, population density, and chemical toxic waste disposal sites. Some of the implications of the study findings are discussed and recommendations made for future investigations.

Adult↗
PubMed2006

A novel index for analysing the response of a microbial culture to changes in the environmental variables during cultivation.

AIMS: To analyse the sensitivity of a microbial culture to variations in the cultivation conditions by using the motile intensity of the cells. METHODS AND RESULTS: Batch cultures of Bacillus thuringiensis were used to study the sensitivity of the cells to pulse changes in pH, temperature and oxygen supply. A droplet of the culture sample was visualized under an optical microscope and the image of the moving cells was captured with a computer controlled display camera attached to the microscope. Motile intensity was computed directly using an image analysis programme. The results showed that the different phases of cell growth exhibited different motile intensities. The motile intensity changed remarkably at the high level of the motile intensity, when the environmental variables are changed. CONCLUSIONS: The product formation was considerably reduced when a disturbance was applied at the high magnitude of motile intensity. SIGNIFICANCE AND IMPACT OF STUDY: Monitoring the motile intensity by image analysis is simple and makes it an attractive method for assessing the effect of environmental variables on the growth and product formation of microbial cultures.

Bacillus thuringiensis↗
PubMed1999

Distribution of the Simulium metallicum complex in Mexico in relation to selected environmental variables.

Larvae of the Simulium metallicum complex (Diptera: Simuliidae) were collected from three foci of human onchocerciasis in Mexico. Specimens were separated into five different cytotypes, identified by morphological characteristics (head pattern and body colour) or polytene chromosome features. Differences were found between foci in the cytotype composition of the S. metallicum complex. Nearly all specimens were cytotype A in the Chamula (97%) and Soconusco (86%) foci. In the Oaxaca focus, however, cytotype I predominated (63%) with 14% cytotype A. Cytotype I comprised only 6% of specimens in the Soconusco focus and was very rare in the Chamula focus. Cytotypes B and H occurred only rarely in all three foci. Cytotype X was found only in Oaxaca. Environmental variables were measured at the collection sites and canonical correspondence analysis (CCA) was used to investigate the associations of cytotype distributions with the following factors: stream size, amount of shade, water clarity, pH, temperature and altitude. Members of the S. metallicum species complex were found to be differentially distributed according to stream conditions and there was a significant correlation between their distributions and the environmental variables. The most important factor in canonical axis 1 of the CCA was pH (t-value -4.38) with temperature (-2.48) and altitude (2.19) having some influence, but the other variables were unimportant. In the second canonical axis, pH (-3.52) was the only variable having a significant effect. Thus, cytotype A was associated with high pH, high temperature and low altitude; B was associated with similar sites but with higher temperatures and at lower average elevations. Cytotype H was found at the centres of the ranges of these variables, I at sites with the lowest temperatures and highest altitudes and X in rivers with the lowest pH.

Animals↗
PubMed2003

First-order differential equation models with estimable parameters as functions of environmental variables and their application to a study of vascular development in young hybrid aspen stems.

A novel method is described for solving systems of differential equations pertaining to organism development, where this development is assumed to be directly influenced by fluctuation in measurable environmental variables. The system parameters are written as functions of these variables and, because these functions involve the accumulation of "environment time" (e.g., "day-degrees"), the system is therefore regulated by the prevailing environmental conditions. This method contrasts with the more usual descriptions of development along a time-line. The parameters of the differential equations involved are estimated by modelling data, which show evidence of changes in the dependent variable(s), i.e. the components of the system. They are expressed in terms of their response to continuous fluctuations in one or more independent, environmental variables. Accumulated thermal time (including day-degrees) or more complex units may be derived by using either linear or nonlinear functions. Critical environmental parameters such as the basal thresholds of a given developmental process or parameters describing a nonlinear relationship with the environment may then be estimated. This paper develops the methodology of this environmentally driven approach to describing organism development in general terms, and gives a specific example of its application with reference to the cellular development within the secondary vascular tissues in the stems of young hybrid aspen trees.

Computational Biology↗
PubMed1979

Role of environmental variability in the evolution of life history strategies.

We reexamine the role of environmental variability in the evolution of life history strategies. We show that normally distributed deviations in the quality of the environment should lead to normally distributed deviations in the logarithm of year-to-year survival probabilities, which leads to interesting consequences for the evolution of annual and perennial strategies and reproductive effort. We also examine the effects of using differing criteria to determine the outcome of selection. Some predictions of previous theory are reversed, allowing distinctions between r and K theory and a theory based on variability. However, these distinctions require information about both the environment and the selection process not required by current theory.

Journal Article↗
PubMedDate not supplied

The stereotypy analysis: an instrument for examining environmental variables associated with differential rates of stereotypic behavior.

The Stereotypy Analysis, a means of analyzing environmental variables associated with differential rates of stereotypic behavior, was conducted with five persons having moderate to profound developmental disabilities. The process involves partial-interval recording of the occurrence of targeted behaviors and the presence/absence of specific environmental events. The Stereotypy Analysis was able to detect environmental events associated with stereotypic responding for 3 of the 5 subjects. Based on the results of the Stereotypy Analysis, indicated and not-indicated interventions were implemented for two subjects. The data obtained using the Stereotypy Analysis were useful in determining effective interventions for those subjects. Providing activities and prompts every 15 s, later faded to every 30 s, reduced handmouthing from a mean of 40% of intervals to 13% for one subject. Providing prompts every 30 s to engage in an activity decreased body rocking from 60% to 15% for the other. Effects for both interventions were replicated using A-B-A-B designs. The not-indicated intervention was unsuccessful for one subject; it suggested multiple control of the behavior for the other. Implications for behavioral theory and practice are discussed.

Adult↗
PubMed1983

The influence of environmental variables on amphetamine-induced activity in the preweanling rat.

The present experiments investigated how environmental stimuli influence a behavioral response to amphetamine treatment in preweanling rats. In the first experiment, 15-day-old rats received either 1 mg/kg d-amphetamine or saline and were observed in the presence of their home shavings or in a novel cage. Results showed that although familiar cues from the home bedding decreased activity of the saline treated pups, these cues did not influence the activity-enhancing effect of amphetamine. In Experiment 2, 15-day-old pups were placed in a cage with an anesthetized adult conspecific and non-directed activity, around the cage, as well as directed activity on top of the adult were recorded. Following amphetamine treatment, animals tested with a conspecific showed no increase in non-directed activity, a finding which replicates previous observations. In the present experiment, however, a significant increase was seen in the activity directed towards or on top of the anesthetized adult. These experiments reveal that familiar cues per se are not sufficient to influence amphetamine-induced activity in young rats. Activity is influenced, specifically if familiar cues are associated with a discrete object. In the presence of a familiar stimulus, non-directed activity is decreased and directed activity is enhanced. These data are discussed in terms of clinical findings which show that amphetamine acts to focus, or direct activity of the hyperactive child, and further underlines the importance of environmental variables in influencing the amphetamine response.

Aging↗
PubMed2004

Benthic diatom community response to environmental variables and metal concentrations in a contaminated bay adjacent to Casey Station, Antarctica.

This study examined the effects of anthropogenic contaminants and environmental variables on the composition of benthic diatom communities within a contaminated bay adjacent to an abandoned waste disposal site in Antarctica. The combination of geographical, environmental and chemical data included in the study explained all of the variation observed within the diatom communities. The chemical data, particularly metal concentrations, explained 45.9% of variation in the diatom communities, once the effects of grain-size and spatial structure had been excluded. Of the metals, tin explained the greatest proportion of variation in the diatom communities (28%). Tin was very highly correlated (R2>0.95) with several other variables (copper, iron, lead, and sum of metals), all of which explained similarly high proportions of total variation. Grain-size data explained 23% of variation once the effects of spatial structure and the chemical data had been excluded. The pure spatial component explained only 1.8% of the total variance. The study demonstrates that much of the compositional variability observed in the bay can be explained by concentrations of metal contaminants.

Antarctic Regions↗
PubMed1992

A preliminary analysis of environmental variables affecting the observed biobehavioural states of individuals with profound handicaps.

Recently, various researchers have recommended investigation of biobehavioural states as a worthwhile endeavour toward providing a more valid assessment of students with profound handicaps. To date, the research conducted in this area has largely focused on the biobehavioural state variable in isolation. This pilot study was conducted to examine the relationships between environmental variables and biobehavioural state variables. Six students with profound handicaps were selected as subjects and observed during normal daily school routines. The investigators discovered significant relationships between the students' prior state, position, grouping type of staff cue given, the proximity of the staff and type of activity stimulus provided, and the students' biobehavioural states. A discussion of the results and recommendations for future research are provided.

Activities of Daily Living↗
PubMed1990

Environmental variables influencing in vitro development of hamster 2-cell embryos to the blastocyst stage.

This study is a systematic analysis of environmental variables influencing development of 2-cell hamster embryos to the blastocyst stage in vitro. Experiments were done using a chemically defined (protein-free) culture medium (HECM-2). Physicochemical variables examined were temperature, the concentrations of CO2, HCO3-, Ca2+, Mg2+, K+, and O2, the presence of a silicone oil overlay, and osmotic pressure. The optimal temperature for development in vitro was 37.5 degrees C; lower temperatures were inhibitory. There was no significant effect on blastocyst development of alterations in the concentrations of NaHCO3, CaCl2, MgCl2, and KCl, or in the ratios of Ca2+:Mg2+ and Na+:K+, over the ranges tested. Development to the blastocyst stage was significantly stimulated by increased CO2 concentrations (7.5% and 10%), by reduced O2 concentrations (10% and 5%), and by the presence of silicone oil overlying the culture medium. Reduction of blastocyst development in the absence of an oil overlay was not caused by increased osmotic pressure. Cleavage stage embryos were not affected by osmolalities ranging from 250 to 350 mOsmols, but blastocyst development was inhibited at greater than or equal to 325 mOsmols. Under optimized conditions (37.5 degrees C, 10% CO2, 25 mM HCO3-, 2.0 mM Ca2+, 0.5 mM Mg2+, 3.0 mM K+, 10% O2, 250-300 mOsmols, with silicone oil overlay), 51-57% of 2-cell hamster embryos developed to the blastocyst stage. This represents a significant improvement over previous "standard" culture conditions, which supported development of 26% blastocysts from 2-cell hamster embryos. The culture system described here provides an adequate baseline response to support detailed investigations into the regulation of embryo development in the hamster.

Animals↗
PubMed2005

Blood lead level in dogs from urban and rural areas of India and its relation to animal and environmental variables.

Lead is a common environmental pollutant with deleterious health effects on human and animal. Industrial and other human activities enhance the lead level in the environment leading to its higher residues in exposed population. The present study was aimed at determining blood lead concentration in dogs from two urban areas and in surrounding rural areas of India and analyzing lead level in dogs in relation to environmental (urban/rural) and animal (age, sex, breed and housing) variables. Blood samples were collected from 305 dogs of either sex from urban (n=277) and unpolluted rural localities (n=28). Irrespective of breed, age and sex, the urban dogs had significantly (P<0.01) higher mean blood lead concentration (0.25+/-0.01 microg/ml) than rural dogs (0.10+/-0.01 microg/ml). The mean blood lead level in stray dogs either from urban or rural locality (0.27+/-0.01 microg/ml) was significantly (P<0.01) higher than that of pets (0.20+/-0.01 microg/ml), and the blood lead concentration was significantly higher in nondescript dogs (0.25+/-0.01 microg/ml) than pedigreed dogs (0.20+/-0.01 microg/ml). The locality (urban/rural) was the major variable affecting blood lead concentration in dogs. Breed and housing of the dogs of urban areas and only housing (pet/stray) in rural areas significantly (P<0.01) influenced the blood lead concentration in dogs.

Animals↗
PubMed1999

Detecting interactions between gene, site, and environmental variables using GAP.

Regressive models that incorporate measured variables and assumed genetic parameters were used to detect interactions between gene, research site, and environmental variables in GAW11 Problem 2. Replicates 1 to 5 were used in the analyses. Significant three-way gene x environment x site interactions were seen for all models, regardless of what assumptions were made about genetic transmission. Therefore, regressive models within each of the four sites were examined for significant gene x environment interactions. At one site, there was a pattern of gene x environment interaction that was consistent in most of the genetic models assumed. Joint and separate segregation and linkage analyses were compared in this site. No patterns of gene x environment interaction were seen in the other sites. Results from this analysis show that regressive modeling can identify complex interactions in data from heterogeneous populations even when ascertainment assumptions are violated.

Chromosome Mapping↗
PubMed2002

Influence of environmental variables on the spatial distribution of PCBs in Norwegian and U.K. soils: implications for global cycling.

This paper reports the influence of environmental variables on soil concentrations of polychlorinated biphenyls (PCBs) and their global fractionation. Soils were sampled from remote woodland (coniferous and deciduous) and grassland locations on a latitudinal transect through the United Kingdom and Norway. Different processes control PCB concentrations and burdens in coniferous, deciduous, and grassland soil systems; these are discussed, with emphasis on the influence of canopy scavenging and soil organic matter (OM) content. In general, concentration differences between sites were 1-2 orders of magnitude for lighter PCBs and 2-3 orders of magnitude for heavier PCBs, when expressed on a pg g(-1) dry weight basis. These differences decreased by up to an order of magnitude when expressed as pg g(-1) OM. The dataset suggests that the more volatile PCBs are moving toward equilibrium with the OM burden of the soil compartment on a European regional scale, while the distribution of the "stickier", heavier homologues appears to still be primarily influenced by their preferential deposition closer to source areas. The relative concentration of the tri- and tetra-PCBs increases with latitude, while that of the hepta- and octa-PCBs decreases, consistent with the global fractionation theory. However, the regression slopes are quite shallow, with high scatter, implying that many environmental and soil-related factors (such as precipitation, organic carbon content and type, other soil properties, local sources, etc.) are also influencing the observed congener patterns. Temperature-driven fractionation, while clearly operating and detectable, needs to be considered in this broader context.

Carbon↗
PubMed2003

Differential prediction of alcohol use and problems: the role of biopsychological and social-environmental variables.

This study examined the differential prediction of alcohol use and problems by biopsychological (i.e., affective and cognitive variables) and social-environmental (i.e., social norms) variables. Undergraduate students (N = 231) were assessed twice separated by a 30-day interval. Time 1 impulsivity, affect lability, social norms, and perceived conflict between personal strivings and alcohol use were each significant predictors of alcohol use-related problems at Time 2 (T2). Structural equation models indicated that impulsivity and affect lability were related directly with use-related problems, while social norms and use-strivings conflict were related indirectly with use-related problems (mediated by use frequency). Impulsivity moderated the T2 use to use-related problems relationship. Use frequency was associated more strongly with use-related problems among more impulsive participants.

Adolescent↗