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Results for “environmental variability”

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PubMed1989

Using developmental theory to guide the search for the effects of biological risk factors on the development of children.

A structural-behavioral model of development is described as providing a basis for formulating hypotheses about the effects of biological risk factors on the development of children. It takes into account the contributions to development that come from organismic and environmental variables. These influences are modified by the effect of individual resiliency in the face of social and biological risk factors. Organismic, environmental, and individual differences are seen as making different contributions in different domains and at different periods of development. A distinction is made between the development of universal and nonuniversal behaviors. From this model, hypotheses can be derived about the effects of social and biological risk factors. The implications for developmental research designs are discussed as are the kinds of behavioral measures most likely to be sensitive enough to detect the effects of social and biological risk factors on the development of children.

Child↗
PubMed1996

Children's methods of coping with stress: a twin study of genetic and environmental influences.

The relative importance of environmental and hereditary factors in how children cope with stress was examined. Emotion-focused, problem-focused, and additional coping variables were assessed in 44 monozygotic (MZ) and 30 dizygotic (DZ) twin pairs, aged 9-16 years. The effects of heritability, shared environment, and unshared environment were examined in structural modelling analyses. Genetic factors accounted for a majority of the reliable variance in four of seven coping variables, while effects of twins' shared environment were negligible for all but one coping variable. Environmental factors important to individual differences in coping strategies were primarily unique to each child (unshared between the twins), highlighting the importance of individual experiences in shaping coping behaviors.

Adaptation, Psychological↗
PubMed1990

[Observational research on the dental compliance of growing children. A behavioral analysis].

Epidemiology has always focused attention on analysis of environmental variables, in addition to biological or physico-chemical elements, that affect the onset and development of dental pathologies. However, other environmental events, such as behavioural repertoires, that may interfere with medical treatment, reducing the chances of recovery, have never been analysed. This study, which was performed in two groups of children aged between six and ten who were examined either inside or outside to school setting, aimed to identify, in addition to the incidence of dental pathologies, the frequency of occurrence of those patterns that risk developing into non-compliant behaviour repertoires to the dentist setting. Results show a generalised response of fear and anxiety in both groups, particularly in older children. It is suggested that the prevention of biological as wall as maladaptive behavioural patterns might lead to a reduction of the social burden determined by the cost of medical care.

Anxiety↗
PubMed2005

Toxic secondary metabolite production in genetically modified potatoes in response to stress.

Potatoes produce a number of toxic secondary metabolites, which are divided into two groups: the sesquiterpenes and the glycoalkaloids (PGAs): whereas PGAs are largely preformed and present in toxic quantities in both the foliage and "green" potatoes, it is well documented that the levels of PGAs and sesquiterpenes are effected by many biotic an abiotic stresses. The development of genetically modified potato varieties has made it prudent to ascertain whether there may be changes in the amounts or types of these secondary metabolites either as a direct effect of the transgene or due to its interactions with environmental variables. Transgenic potato lines were exposed, along with nontransgenic lines, to a range of biotic and abiotic stresses and a range of environmental conditions in the field and store. Following stressing, a comparison was made of levels of potato glycoalkaloid and sesquiterpene levels between the two groups. Significant differences were observed in the levels of both glycoalkaloid and sesquiterpene levels between transgenic and control material and between infected and noninfected material.

Alkaloids↗
PubMedDate not supplied

Evaluating enrichment program study groups: academic outcomes, psychological outcomes, and variables influencing retention.

The purpose of this study was to describe and evaluate select aspects of an enrichment program (EP) for students who participated in peer mentor/tutor (PMT) led study groups throughout the semester. The evaluation addressed three areas related to the underlying conceptual framework: (1) academic outcomes; (2) psychological outcomes (satisfaction); and (3) variables influencing retention. Overall, study group participants achieved higher pass rates, lower withdrawal rates, and positive psychological outcomes (satisfaction). Students perceived that environmental variables were more influential than academic variables in influencing retention. Social integration variables were perceived as greatly supportive. Implications for nurse educators are discussed.

Adult↗
PubMed1989

Use of dental services among Danish youths: role of the social environment, the individual, and the delivery system.

The purpose of the present study was to analyze the separate effect and the total effect of the social environment, the individual and the delivery system on frequency of use of dental services among youths. The variables of use were divided into the three main groups according to Coleman (12). Information concerning use of dental services, individual and structural variables was obtained by a self-administered questionnaire to 756 Danes 20-21 yr old in 1984-85. Information concerning social environmental variables was obtained by a postal questionnaire to the mothers of the individuals in 1974 (16). Information from 552 mothers was available. Firstly, the variables concerning the social environment were inserted into a multiple dummy regression analysis as independent variables, and it was found that the following characteristics of the mothers were significant predictors: regularity of dental visits and perceived economic barriers. Secondly, the variables concerning the individual resources were set into a multiple dummy regression model as independent variables. The results showed that the following variables had a significant effect: sex, social conditions, pain tolerance, dental anxiety, and perceived economic barriers. Thirdly, multiple dummy regression analysis showed that among the structural variables general assessment of Child Dental Care compared to Youth Dental Care, and a personality assessment of the general dental practitioner were significant predictors. Finally the predictors from the three main groups all together were inserted as independent dummy variables into a regression model. The results showed that sex, social conditions, pain tolerance, dental anxiety, perceived economic barriers of the youth themselves, general assessment of Child Dental Care compared to Youth Dental Care were significant predictors.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Head injury, a multivariate study: predicting long-term productivity and independent living outcome.

As the second of a two-part research project, this study attempted to build three clinically useful prediction equations; these equations would be used to predict three long-term functional outcomes: productivity status, living arrangement status, number of hours of assistance required per week. There were ten predictor variables used in each analysis. These ten variables belonged to four theoretical classes: pre-injury demographics, pre-injury social characteristics, severity of injury, and post-injury environmental variables. The analytical method used was the General Linear Model of multiple regression, rather than the most often used Stepwise regression procedure. The results indicate that in none of the three prediction equations was more than 28% of the criterion variance accounted for, and only a minority of the predictor variables were significant predictors. It is concluded that, while the equations are of only very limited utility, the theoretical model and the analytical technique will be useful for future investigators.

Activities of Daily Living↗
PubMedDate not supplied

[Extracurricular activities of adolescents useful for smoking prevention programs. OCTOPUS team].

BACKGROUND: The cigarette smoking habit continues to be prevalent to a greater degree than would be desirable among teenagers. Innovative prevention programs are needed. This descriptive cross-sectional study sets out the behavior variables related to the cigarette smoking habit and the extracurricular activities in which teenagers are most frequently involved which are useful for setting out extracurricular prevention programs. METHODS: The data was collected by means of a questionnaire validated in a representative sample of school age youths (ages 10-11 and 13-14) from Asturias. The variables entailed in cigarette smoking were analyzed using the regression method. RESULTS: The starting smoker percentage is 14.5%-42.5%, regular smokers totaling 1.1% and 12.4%, respectively. Two models were constructed with the variables significantly related to smoking behavior, which are properly classified into smoker/non-smoker by 98.85% and 91.39% of the children, by ages. The environmental variables (availability of cigarettes and alcoholic beverages and regular visits to places entailing risk) are the major aspects comprising the model. The most common extracurricular activities are: watching TV, reading and listening to music and watching or playing sports. CONCLUSION: The findings provide keys to planning extracurricular activities tailored to fit in with the activities most popular among teens: TV commercials and ads on music media (CD's, tapes, etc.) and printed information mailed directly to teens at their homes, with messages conveyed by opinion-leaders among teens in the fields of sports, music and television.

Adolescent↗
PubMed2004

[Differential diagnostic correlations of sleep and attention disorders in childhood--comorbid psychological and organic illnesses].

Sleep disorders in childhood are a common phenomenon. A highly differenciated diagnostic effort is required as sleep in children is extremely variable between individuals, undergoes a constant natural development and depends of cultural influences on sleep behavior. The pathogenesis is predominantly due to environmental variables, especially to the child-parent interaction. Besides somatic diseases, as Sleep Related Breathing Disorders, Restless legs syndrome and nocturnal seizures play an etiologic role. Psychological and somatic factors in the development of sleep disorders have in common that they exercise a serious negative impact on cognitive daytime functioning and behavior. In this paper the interdependence of somatic and psychological factors and the relations between disturbed nighttime sleep and impaired daytime functioning will be discussed. Especially in Attention-Deficit Hyperactivity Disorder these relations can be demonstrated. Conclusions are drawn for a specific, stepwise diagnostic approach in children's sleep disorders.

Adolescent↗
PubMed1996

[The nature of personality: a co-evolutionary perspective].

Personality psychologists' attempts to explain human diversity have traditionally focused upon processes of person-situation interaction, and genotype-environment interaction. The great variability of genotypes and environments within cultures has remained unexplained in these efforts. Which processes may be responsible for the genetic and environmental variability within cultures? Answers to this question are sought in processes of genetic-cultural coevolution: mutation and sexual recombination of genes, innovation and synthesis of memes (units of cultural transmission), genotype-->environment and meme-->environment effects, and frequency-dependent natural and cultural selection. This twofold evolutionary explanation of personality differences within cultures suggests that a solid foundation of personality psychology requires bridging biology and cultural science.

Biological Evolution↗
PubMed1985

Concern for appropriateness as a moderator variable in the statistical explanation of self-reported use of alcohol and marijuana.

Two studies examine the Concern for Appropriateness Scale (Lennox & Wolfe, 1984) as a likely moderator of dispositional and environmental variables associated with self-reported use of alcohol and marijuana by college and precollege students. In Study 1, data from 408 upper division students show that concern score interacts significantly with religiosity in analyses of use of both drugs, but not with any of 11 other dispositional variables nor with drug-specific environment predictors in analyses of use of either drug. In Study 2, data from 242 recent high school graduates show that concern score interacts significantly with religiosity and drug-specific environment in the explanation of alcohol use but not in the explanation of marijuana use. All of the significant interactions are in the predicted direction. Results therefore suggest that the concern scale is valid for some of its intended purposes.

Adolescent↗
PubMedDate not supplied

[The effect of physical and chemical environmental factors on the growth of Pseudomonas aeruginosa dissociants].

The growth rates of the R-, S-, and M-dissociants of a hydrocarbon oxidizing strain of Pseudomonas aeruginosa were comparatively studied under variable environmental conditions (aeration, temperature, pH, UV radiation, and concentration of NaCl). The R-dissociant was found to be more tolerant to UV radiation, high aeration, and temperature. The S-dissociant, which is the most effective in degrading hydrocarbons, gains a selection advantage under acidic conditions. The M-dissociant has advantages over the other dissociants under conditions of decreased aeration, low temperature, and high concentration of NaCl. The results of this work are important for optimizing microbial growth conditions and for identification of bacteria. Probably, the biological sense of dissociation is to broaden the boundaries within which a species can survive under changeable environmental conditions.

Culture Media↗
PubMed2004

The effect of soil composition and hydration on the bioavailability and toxicity of cadmium to hibernating juvenile American toads (Bufo americanus).

The soil ecotoxicology literature has focused primarily on a few major taxa, to the neglect of other fossorial organisms such as amphibians. We selected cadmium (Cd) and the American toad (Bufo americanus) as a model contaminant and biological species to assess the impact of soil contamination on amphibian hibernation survival and post-hibernation condition. Soil sand composition (50, 70, 90%) and hydration (100, 150% water holding capacity (WHC)) were manipulated in addition to Cd concentration (0, 56, 165, 483 microg/g) to determine whether these soil properties affect toxicity. Soil Cd concentration significantly reduced survival and locomotor performance, and was correlated negatively with percent mass loss and positively with whole body Cd concentration. Higher sand content resulted in less mass loss and greater Cd uptake. Toads that were hibernated in 50% sand hydrated to 100% WHC had higher survival, less mass loss, and better sprint performance than those hibernated in 50% sand, 150% WHC. This study demonstrates that concentrations of Cd found in soil at highly contaminated sites can be bioaccumulated by hibernating amphibians and may reduce fitness. Differences in microhabitat use may cause species to vary in their exposure and susceptibility to soil contamination. The toxicity of Cd to amphibians could be greater in natural systems where there are multiple stressors and fluctuations in environmental variables.

Animals↗
PubMed2006

Ecological quality status of coastal benthic ecosystems in the Sea of Marmara.

The macrofauna in the north Marmara Sea were identified and evaluated with univariate measures and biotic indices (BENTIX, AMBI). As expected, the diversity and species' variety decreased as the sediments became muddier and as the stress increased. The AMBI index failed to detect the spatial differentiation of the EcoQ between the sites whereas, the BENTIX index succeeded (in 70% of the cases) in producing an ecologically relevant classification reflecting the environmental pressures. Results suggested that risks of reduced species' richness and diversity from organic loading and other associated stressors in sediments should be relatively low at TOC concentrations < about 6 mg/g, high at concentrations>about 22 mg/g, and intermediate at concentrations in-between. It is suggested that these TOC critical points may be used as a general screening-level indicator for assessing the EcoQ in association with reduced biodiversity over coastal areas receiving organic wastes and other pollutants from human activities. It is further suggested that both assignment of species to ecological groups and classification scales for biotic indices (AMBI, BENTIX) for sites in the Mediterranean Sea should be readjusted so as to be closer related to environmental variables.

Animals↗
PubMed2004

Investigating the affinities and persistence of VX nerve agent in environmental matrices.

Laboratory experiments were conducted to determine environmental variables that affect the affinities and persistence of the nerve agent O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothiolate (VX) at dilute concentrations in environmental matrices. Quantitative analyses of VX and its degradation products were performed using LC-MS. Batch hydrolysis experiments demonstrated an increasing hydrolysis rate as pH increased, as shown in previous studies, but also indicated that dissolved aqueous constituents can cause significant differences in the absolute hydrolysis rate. Adsorption isotherms from batch aqueous experiments revealed that VX has a high affinity for hydrophobic organics, a moderate affinity for montmorillonite clay, and a very low affinity for an iron-oxyhydroxide soil mineral, goethite. The adsorption on goethite was increased with the presence of dissolved organic matter in solution. VX degraded rapidly when dried onto goethite, when specific adsorption was forced. No enhanced degradation occurred with goethite in small amounts of water. These results suggest that aqueous conditions have important controls on VX adsorption and degradation in the environment and a more mechanistic understanding of these controls is needed in order to enable accurate predictions of its long-term fate and persistence.

Adsorption↗
PubMed2004

Comparison of risk factor profiles concerning self-reported skin complaints and objectively determined skin symptoms in German office workers.

The correspondence between impact factor profiles of self-reported skin sensation and of objectively determined skin symptoms was examined using data from the ProKlimA project (1994-1999). A sub-sample of 925 office workers participated in measurements of skin hydration and sebum content and responded to a questionnaire assessing sensory perception. The calculation of multiple logistic regression models revealed a significant increased risk for female sex [Odds ratio (OR): 2.3; confidence interval (CI): 1.4-3.6], poor software (OR: 2.2; CI: 1.3-4.0), unfavorable job characteristics (OR: 1.8; CI: 1.1-2.8), allergic illness (OR: 1.5; CI: 1.1-2.2) and the use of skin cream (OR:2.6; CI: 1.6-4.4) on the subjective perception of skin sensation. Regarding the objective medical examination of the skin humidity a significant increased risk was detected for a high concentration of Total Volatile Organic Compounds (OR: 2.5; CI: 1.3-4.8) and a low relative humidity (OR:1.9; CI: 1.1-3.4). The likewise objectively measured low sebum content is not associated with environmental variables. The impact profiles on subjective vs. objective outcome variables differ in a clear and typical way. Skin related sensory perception is mainly influenced by job-related and personal impacts. Indoor environmental characteristics affect skin hydration. We conclude the need to develop, to adapt and to use objective clinical methods applicable for field monitoring parallel to questioning.

Adult↗
PubMed1999

Epidemiology of tobacco use among US adolescents.

Among persons in the United States under age 18 years, every day more than 6000 try cigarette smoking for the first time and more than 3000 become daily smokers. The overwhelming majority of adults who smoke began by age 18 years. Slightly more than one-third of US high school students were cigarette smokers in 1997. In recent years, males were about as likely as females to smoke. American Indians/Alaska Natives and whites were more likely to smoke than were Hispanics, African-Americans, and Asian-Americans/Pacific Islanders. Overall, cigarette smoking prevalence declined in the late 1970s or early 1980s, leveled off in the 1980s, and increased in the 1990s. The decline in prevalence among African-Americans was especially noteworthy. Among US high school students in 1997, the prevalence of cigar smoking was higher than that of smokeless tobacco use. Indicators of nicotine dependence are prevalent among adolescents who use tobacco products. Efforts to: (1) improve the validity of self-reported behaviors; (2) increase access to school dropouts and infrequent school attendees; and (3) improve school participation rates, data availability, and data linkage systems will benefit the field. Qualitative research can suggest variables to be added to survey questionnaires. Methods research should be conducted to better quantify and explain differences between survey estimates. Tracking relevant environmental variables and new tobacco products will expand the science base and facilitate appropriate public health action.

Adolescent↗
PubMed2003

Fungal colonization of shrub willow roots at the forefront of a receding glacier.

Shrub willows ( Salix spp.) form associations with arbuscular mycorrhizal (AM), ectomycorrhizal (EM) and dark septate endophytic (DSE) fungi. Willow root colonization by these three types of fungi was studied on a deglaciated forefront of Lyman Glacier, Washington, USA. Root colonization was low; less than 1% of the root length was colonized by AM and 25.6% by DSE. EM colonized 25% of the root tips and 19.4% of the root length. AM and DSE colonization were not related to distance from the present glacier terminus or to canopy cover. EM colonization increased with distance from the glacier terminus based on gridline intercept data but not on root tip frequency data. Availability of propagules in the substrate was low, but numbers of propagules increased with distance from the glacier terminus. The EM communities were dominated by three ascomycetes showing affinity to Sordariaceae in BLAST analyses. Other frequent taxa on the glacier forefront included species of Cortinariaceae, Pezizaceae, Russulaceae, Thelephoraceae and Tricholomataceae. When occurrence of individual taxa was used as a response variable to canopy cover, distance from the glacier terminus, and their interaction, four different fungal guilds were identified: 1) fungi that did not respond to these environmental variables; 2) fungi that occurred mainly in intercanopy areas and decreased with distance from the glacier terminus; 3) fungi that were insensitive to canopy cover but increased with distance from the glacier terminus; 4) fungi that occurred mainly under willow canopies and increased with distance from the glacier terminus. We suggest that fungal colonization is mainly limited by fungal propagule availability. Environmental conditions may also limit successful establishment of plant-fungus associations. We propose that the four EM guilds partly explain successional dynamics. The initial EM community comprises fungi that tolerate low organic matter and nitrogen environment (first and second guilds above). During later community development, these fungi are replaced by those that benefit from an increased organic matter and nitrogen environment (third and fourth guilds above).

Ascomycota↗