926 resultados para self-organizing maps of Kohonen


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Report published in the Proceedings of the National Conference on "Education and Research in the Information Society", Plovdiv, May, 2015

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Background: Self-testing technology allows people to test themselves for chlamydia without professional support. This may result in reassurance and wider access to chlamydia testing, but anxiety could occur on receipt of positive results. This study aimed to identify factors important in understanding self-testing for chlamydia outside formal screening contexts, to explore the potential impacts of self-testing on individuals, and to identify theoretical constructs to form a Framework for future research and intervention development. Methods: Eighteen university students participated in semi-structured interviews; eleven had self-tested for chlamydia. Data were analysed thematically using a Framework approach. Results: Perceived benefits of self-testing included its being convenient, anonymous and not requiring physical examination. There was concern about test accuracy and some participants lacked confidence in using vulvo-vaginal swabs. While some participants expressed concern about the absence of professional support, all said they would seek help on receiving a positive result. Factors identified in Protection Motivation Theory and the Theory of Planned Behaviour, such as response efficacy and self-efficacy, were found to be highly salient to participants in thinking about self-testing. Conclusions: These exploratory findings suggest that self-testing independently of formal health care systems may no more negatively impact people than being tested by health care professionals. Participants’ perceptions about self-testing behaviour were consistent with psychological theories. Findings suggest that interventions which increase confidence in using self-tests and that provide reassurance of test accuracy may increase self-test intentions.

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Expansive periphyton mats are a striking characteristic of the Florida Everglades. Floating periphyton mats are home to a diverse macroinvertebrate community dominated by chironomid and ceratopogonid larvae and amphipods that use the mat as both a food resource and refuge from predation. While this periphyton complex functions as a self-organizing system, it also serves as a base for trophic interactions with larger organisms. The purpose of my research was to quantify variation in the macroinvertebrate community inhabiting floating periphyton mats, describe the role of mats in shaping food-web dynamics, and describe how these trophic interactions change with eutrophication. ^ I characterized the macroinvertebrate community inhabiting periphyton through a wet-season by describing spatial variation on scales from 0.2 m to 3 km. Floating periphyton mats contained a diverse macroinvertebrate community, with greater taxonomic richness and higher densities of many taxa than adjacent microhabitats. Macroinvertebrate density increased through the wet season as periphyton mats developed. While some variation was noted among sites, spatial patterns were not observed on smaller scales. I also sampled ten sites representing gradients of hydroperiod and nutrient (P) levels. The density of macroinvertebrates inhabiting periphyton mats increased with increasing P availability; however, short-hydroperiod P-enriched sites had the highest macroinvertebrate density. This pattern suggests a synergistic interaction of top-down and bottom-up effects. In contrast, macroinvertebrate density was lower in benthic floc, where it was negatively correlated with hydroperiod. ^ I used two types of mesocosms (field cages and tanks) to manipulate large consumers (fish and grass shrimp) with inclusion/exclusion cages over an experimental P gradient. In most cases, periphyton mats served as an effective predation refuge. Macroinvertebrates were consumed more frequently in P-enriched treatments, where mats were also heavily grazed. Macroinvertebrate densities decreased with increasing P in benthic floc, but increased with enrichment in periphyton mats until levels were reached that caused disassociation of the mat. ^ This research documents several indirect trophic interactions that can occur in complex habitats, and emphasizes the need to characterize dynamics of all microhabitats to fully describe the dynamics of an ecosystem. ^

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This study investigated the effectiveness of goal setting and attributional feedback on self-efficacy for writing and writing achievement of students who are gifted underachievers. Students in grades 3, 4 and 5 participated. Five dependent measures were investigated: fluency, syntax, range, diversity and organization. The results indicated that a systematic writing instruction program increased self-efficacy for writing. In addition the self-efficacy strategies of goal setting and attributional feedback improve self-efficacy and increased some areas of writing achievement. The dependent measures most affected were fluency, syntax and organization. The students in this study did not improve their levels of vocabulary. This study included many practical applications for teachers to use in a classroom setting. ^

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This study examined relationships among self-esteem, remedial academic placement, ethnicity, gender, and enrollment status, using a nonexperimental, ex post facto research design. Participants were 113 freshman community college students attending Broward Community College in South Florida. The Coopersmith Self-Esteem Inventory (Adult Form) was used to measure the self-esteem of the participants. The results of this study indicate a significant difference between the mean self-esteem levels of the students enrolled in remedial academic classes (m = 66.08) and those enrolled in regular academic classes (m = 73.97). An independent samples t-test at the.05 significance level indicated that regular students were found to have higher levels of self-esteem than remedial students (t(112) = 2.14, p =.03). Two-way analyses of variance of placement status by ethnicity, of placement status by gender, and of placement status by enrollment status on self-esteem were also conducted. Interactions between placement status and the other factors were not found to be significant (p $>$.05). However, a significant main effect for ethnicity was found (p $<$.05). The results indicated that white students had a mean self-esteem level (m = 75.30) significantly higher than non-white students (m = 62.76, p =.002).^ The results of this study suggests that many community college students have problems related to self-esteem. Further research should be conducted on remedial and minority college students using a larger sample size and additional variables, such as socio-economic status. ^

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Within the Stage II program evaluation of the Miami Youth Development Project's (YDP) Changing Lives Program (CLP), this study evaluated CLP intervention effectiveness in promoting positive change in emotion-focused identity exploration (i.e. feelings of personal expressiveness; PE) and a "negative" symptom of identity development (i.e. identity distress; ID) as a first step toward the investigation of a self-transformative model of identity development in adolescent youth. Using structural equation modeling techniques, this study found that participation in the CLP is associated with positive changes in PE (path = .841, p < .002), but not changes in ID. Increase in ID scores was found to be associated with increases in PE (path = .229, p < .002), as well. Intervention effects were not moderated by age/stage, gender, or ethnicity, though differences were found in the degree to which participating subgroups (African-American/Hispanic, male/female, 14-16 years old/17-19 years old) experience change in PE and ID. Findings also suggest that moderate levels of ID may not be deleterious to identity exploration and may be associated with active exploration. ^

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Within the Stage II program evaluation of the Miami Youth Development Project's (YDP) Changing Lives Program (CLP), this study evaluated CLP intervention effectiveness in promoting positive change in emotion-focused identity exploration (i.e. feelings of personal expressiveness; PE) and a "negative" symptom of identity development (i.e. identity distress; ID) as a first step toward the investigation of a self-transformative model of identity development in adolescent youth. Using structural equation modeling techniques, this study found that participation in the CLP is associated with positive changes in PE (path = .841, p < .002), but not changes in ID. Increase in ID scores was found to be associated with increases in PE (path = .229, p < .002), as well. Intervention effects were not moderated by age/stage, gender, or ethnicity, though differences were found in the degree to which participating subgroups (African- American/Hispanic, male/female, 14-16 years old/17-19 years old) experience change in PE and ID. Findings also suggest that moderate levels of ID may not be deleterious to identity exploration and may be associated with active exploration.

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We completely determine the spectra of composition operators induced by linear fractional self-maps of the unit disc acting on weighted Dirichlet spaces; extending earlier results by Higdon [8] and answering the open questions in this context.

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We analyze a recent proposal for spontaneous mirror symmetry breaking based on the coupling of first-order enantioselective autocatalysis and direct production of the enantiomers that invokes a critical role for intrinsic reaction noise. For isolated systems, the racemic state is the unique stable outcome for both stochastic and deterministic dynamics when the system is in compliance with the constraints dictated by the thermodynamics of chemical reaction processes. In open systems, the racemic outcome also results for both stochastic and deterministic dynamics when driving the auto-catalysis unidirectionally by external reagents. Nonracemic states can result in the latter only if the reverse reactions are strictly zero: these are kinetically controlled outcomes for small populations and volumes, and can be simulated by stochastic dynamics. However, the stability of the thermodynamic limit proves that the racemic outcome is the unique stable state for strictly irreversible externally driven autocatalysis. These findings contradict the suggestion that the inhibition requirement of the Frank autocatalytic model for the emergence of homochirality may be relaxed in a noise-induced mechanism.

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Background. The Scale for Psychosocial Factors in Food Allergy (SPS-FA) is based on the biopsychosocial model of health and was developed and validated in Chile to measure the interaction between psychological variables and allergy symptoms in the child. We sought to validate this scale in an English speaking population and explore its relationship with parental quality of life, self-efficacy, and mental health. Methods. Parents (n = 434) from the general population in the UK, who had a child with a clinical diagnosis of food allergy, completed the SPS-FA and validated scales on food allergy specific parental quality of life (QoL), parental self-efficacy, and general mental health. Findings. The SPS-FA had good internal consistency (alphas = .61-.86). Higher scores on the SPS-FA significantly correlated with poorer parental QoL, self-efficacy, and mental health. All predictors explained 57% of the variance in SPS-FA scores with QoL as the biggest predictor (β = .52). Discussion. The SPS-FA is a valid scale for use in the UK and provides a holistic view of the impact of food allergy on the family. In conjunction with health-related QoL measures, it can be used by health care practitioners to target care for patients and evaluate psychological interventions for improvement of food allergy management.

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Self-report measures of cognitive problems may have value, but there are indications that scores on such measures are influenced by other factors such as personality. In an online correlational study, 523 non-clinical volunteers completed measures of personality, digit span, and the Prospective and Retrospective Memory Questionnaire. Self-reported prospective and retrospective memory failures were associated positively with neuroticism and negatively with conscientiousness, but not with digit span performance. These findings are consistent with other indications that conscientiousness and neuroticism may underpin self-reports of cognitive problems.

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PURPOSE Suicide is a leading cause of death among adolescents. Self-harm is the most important risk factor for suicide, yet the majority of self-harm does not come to the attention of health services. The purpose of this study was to establish the relative incidence of adolescent suicide, hospital-treated self-harm and self-harm in the community. METHODS Annual suicide rates were calculated for 15-17 year-old in the Cork and Kerry region in Ireland based on data from the Central Statistics Office. Rates of hospital-treated self-harm were collected by the Irish National Registry of Deliberate Self-Harm. Rates of self-harm in the community were assessed using a survey of 3,881 adolescents, the Child and Adolescent Self-harm in Europe study. RESULTS The annual suicide rate was 10/100,000. Suicide was six times more common among boys than girls. The annual incidence rate of hospital-treated self-harm was approximately 344/100,000, with the female rate almost twice the male rate. The rate of self-harm in the community was 5,551/100,000, and girls were almost four times more likely to report self-harm. For every boy who died by suicide, 16 presented to hospital with self-harm and 146 reported self-harm in the community. For every female suicide, 162 girls presented to hospital with self-harm and 3,296 reported self-harm. CONCLUSIONS Gender differences in relative rates of self-harm and suicide are very large, with boys who have harmed themselves at particularly high risk of suicide. Knowledge of the relative incidence of self-harm and suicide in adolescents can inform prevention programmes and services.

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Thesis (Ph.D.)--University of Washington, 2016-08

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In this thesis, I studied self-efficacy in the learning of English and Swedish in Finland. The theory of self-efficacy, which was created by Albert Bandura, suggests that the beliefs a person has of his or her capabilities in a certain task affect the person’s performance in the task. My aim was to study whether there are differences in self-efficacy beliefs between the learners of English and Swedish, and whether these beliefs correlate with the performance in the language in question. My hypotheses were that the learners of English have higher self-efficacy beliefs than the learners of Swedish and that self-efficacy beliefs correlate with language performance. The study was quantitative, and it consisted of a self-efficacy questionnaire and a language test which were distributed to students of English and Swedish in an upper secondary school in Rovaniemi. The study was answered by 137 students, of whom 93 were learners of English and 44 were learners of Swedish. The results indicated that the learners of English had a higher sense of efficacy than the learners of Swedish. The analysis proved that there was a significant correlation between English students’ self-efficacy and their performance in the language measured by the test and the grades. In addition, a significant correlation existed between Swedish students’ self-efficacy and their grades. However, there was no correlation between the Swedish students’ self-efficacy and their test results. The difference in the self-efficacy beliefs of the two language groups indicates that people in Finland are more confident in using English than Swedish, which also implies that English is more valued in Finnish society than Swedish. It is important to acknowledge the lower self-efficacy beliefs in Swedish because various studies have proven that self-efficacy affects academic achievement. As a suggestion for further research, the self-efficacy beliefs of different language groups could be compared in a qualitative study in order to understand the development of self-efficacy more profoundly.

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The dissertation is devoted to the study of problems in calculus of variation, free boundary problems and gradient flows with respect to the Wasserstein metric. More concretely, we consider the problem of characterizing the regularity of minimizers to a certain interaction energy. Minimizers of the interaction energy have a somewhat surprising relationship with solutions to obstacle problems. Here we prove and exploit this relationship to obtain novel regularity results. Another problem we tackle is describing the asymptotic behavior of the Cahn-Hilliard equation with degenerate mobility. By framing the Cahn-Hilliard equation with degenerate mobility as a gradient flow in Wasserstein metric, in one space dimension, we prove its convergence to a degenerate parabolic equation under the framework recently developed by Sandier-Serfaty.