957 resultados para CURRENT SELF-OSCILLATION


Relevância:

30.00% 30.00%

Publicador:

Resumo:

Spectroscopic catalogues, such as GEISA and HITRAN, do not yet include information on the water vapour continuum that pervades visible, infrared and microwave spectral regions. This is partly because, in some spectral regions, there are rather few laboratory measurements in conditions close to those in the Earth’s atmosphere; hence understanding of the characteristics of the continuum absorption is still emerging. This is particularly so in the near-infrared and visible, where there has been renewed interest and activity in recent years. In this paper we present a critical review focusing on recent laboratory measurements in two near-infrared window regions (centred on 4700 and 6300 cm−1) and include reference to the window centred on 2600 cm−1 where more measurements have been reported. The rather few available measurements, have used Fourier transform spectroscopy (FTS), cavity ring down spectroscopy, optical-feedback – cavity enhanced laser spectroscopy and, in very narrow regions, calorimetric interferometry. These systems have different advantages and disadvantages. Fourier Transform Spectroscopy can measure the continuum across both these and neighbouring windows; by contrast, the cavity laser techniques are limited to fewer wavenumbers, but have a much higher inherent sensitivity. The available results present a diverse view of the characteristics of continuum absorption, with differences in continuum strength exceeding a factor of 10 in the cores of these windows. In individual windows, the temperature dependence of the water vapour self-continuum differs significantly in the few sets of measurements that allow an analysis. The available data also indicate that the temperature dependence differs significantly between different near-infrared windows. These pioneering measurements provide an impetus for further measurements. Improvements and/or extensions in existing techniques would aid progress to a full characterisation of the continuum – as an example, we report pilot measurements of the water vapour self-continuum using a supercontinuum laser source coupled to an FTS. Such improvements, as well as additional measurements and analyses in other laboratories, would enable the inclusion of the water vapour continuum in future spectroscopic databases, and therefore allow for a more reliable forward modelling of the radiative properties of the atmosphere. It would also allow a more confident assessment of different theoretical descriptions of the underlying cause or causes of continuum absorption.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Ruminant husbandry is a major source of anthropogenic greenhouse gases (GHG). Filling knowledge gaps and providing expert recommendation are important for defining future research priorities, improving methodologies and establishing science-based GHG mitigation solutions to government and non-governmental organisations, advisory/extension networks, and the ruminant livestock sector. The objectives of this review is to summarize published literature to provide a detailed assessment of the methodologies currently in use for measuring enteric methane (CH4) emission from individual animals under specific conditions, and give recommendations regarding their application. The methods described include respiration chambers and enclosures, sulphur hexafluoride tracer (SF6) technique, and techniques based on short-term measurements of gas concentrations in samples of exhaled air. This includes automated head chambers (e.g. the GreenFeed system), the use of carbon dioxide (CO2) as a marker, and (handheld) laser CH4 detection. Each of the techniques are compared and assessed on their capability and limitations, followed by methodology recommendations. It is concluded that there is no ‘one size fits all’ method for measuring CH4 emission by individual animals. Ultimately, the decision as to which method to use should be based on the experimental objectives and resources available. However, the need for high throughput methodology e.g. for screening large numbers of animals for genomic studies, does not justify the use of methods that are inaccurate. All CH4 measurement techniques are subject to experimental variation and random errors. Many sources of variation must be considered when measuring CH4 concentration in exhaled air samples without a quantitative or at least regular collection rate, or use of a marker to indicate (or adjust) for the proportion of exhaled CH4 sampled. Consideration of the number and timing of measurements relative to diurnal patterns of CH4 emission and respiratory exchange are important, as well as consideration of feeding patterns and associated patterns of rumen fermentation rate and other aspects of animal behaviour. Regardless of the method chosen, appropriate calibrations and recovery tests are required for both method establishment and routine operation. Successful and correct use of methods requires careful attention to detail, rigour, and routine self-assessment of the quality of the data they provide.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

This article compares the efficiency of induced polarization (IP) and resistivity in characterizing a contamination plume due to landfill leakage in a typical tropical environment. The resistivity survey revealed denser electrical current flow that induced lower resistivity values due to the high ionic content. The increased ionic concentration diminished the distance of the ionic charges close to the membrane, causing a decrease in the IP phenomena. In addition, the self-potential (SP) method was used to characterize the preferential flow direction of the area. The SP method proved to be effective at determining the flow direction; it is also fast and economical. In this study, the resistivity results were better correlated with the presence of contamination (lower resistivity) than the IP (lower chargeability) data.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Solar-powered vehicle activated signs (VAS) are speed warning signs powered by batteries that are recharged by solar panels. These signs are more desirable than other active warning signs due to the low cost of installation and the minimal maintenance requirements. However, one problem that can affect a solar-powered VAS is the limited power capacity available to keep the sign operational. In order to be able to operate the sign more efficiently, it is proposed that the sign be appropriately triggered by taking into account the prevalent conditions. Triggering the sign depends on many factors such as the prevailing speed limit, road geometry, traffic behaviour, the weather and the number of hours of daylight. The main goal of this paper is therefore to develop an intelligent algorithm that would help optimize the trigger point to achieve the best compromise between speed reduction and power consumption. Data have been systematically collected whereby vehicle speed data were gathered whilst varying the value of the trigger speed threshold. A two stage algorithm is then utilized to extract the trigger speed value. Initially the algorithm employs a Self-Organising Map (SOM), to effectively visualize and explore the properties of the data that is then clustered in the second stage using K-means clustering method. Preliminary results achieved in the study indicate that using a SOM in conjunction with K-means method is found to perform well as opposed to direct clustering of the data by K-means alone. Using a SOM in the current case helped the algorithm determine the number of clusters in the data set, which is a frequent problem in data clustering.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

It has been proposed that low birth weight is associated with high levels of blood pressure in later life. The aim of this study was to assess the relationship of blood pressure to birth weight and current body size during growth and adulthood. A total of 711 female multiple births, with one group of 244 in their growth phase mean age 12.0 (2.3)(SD) years and the other of 467 adults (mean age 35.2 (12.6) years), had height, weight and both systolic (SBP) and diastolic (DBP) blood pressures measured, and self-reported their birth weight. Regression analyses were performed to assess the cross-sectional and within-pair associations of blood pressure to birth weight, with and without adjustments for current body size. Within-pair analysis was based on 296 twin pairs. Cross-sectionally, a reduction in birth weight of 1 kg was associated with 2 to 3 mm Hg higher age-adjusted SBP, which was of marginal significance and explained about 2% of the population variance. Adjustment for body mass index did not significantly change this association. Within-pair analyses found no association between birth weight and SBP or DBP,even after adjusting for current body size. After age, current body size was the strongest predictor of systolic BP. The weak association of blood pressure to birth weight cross-sectionally is of interest, but any within-pair effect of birth weight on blood pressure must be minimal compared with the effect of current body size.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The role of adult romantic attachment style in the relationship between childhood experiences and current depression was examined. Childhood maltreatment, parental separation/divorce, family adaptability and cohesion during childhood, current attachment style in romantic relationships, vulnerability to depression, and current depressive symptoms were measured in a self-selected sample of adults (N = 133). A large degree of overlap was found in the experience of different types of maltreatment during childhood. Depressive symptoms were uniquely predicted by the sexual abuse and neglect scales, with significant additional variance explained after entering the degree to which respondents' current romantic attachment style was “secure”. Maltreatment and family dysfunction in childhood were significant predictors of depression and vulnerability to depression. Although maltreatment scores did not differentiate between different attachment styles, the degree to which respondents were securely attached may explain -in part -the association between early childhood environment and depressive symptoms in adulthood.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

An effective scheme for soccer summarization is significant to improve the usage of this massively growing video data. The paper presents an extension to our recent work which proposed a framework to integrate highlights into play-breaks to construct more complete soccer summaries. The current focus is to demonstrate the benefits of detecting some specific audio-visual features during play-break sequences in order to classify highlights contained within them. The main purpose is to generate summaries which are self-consumable individually. To support this framework, the algorithms for shot classification and detection of near-goal and slow-motion replay scenes is described. The results of our experiment using 5 soccer videos (20 minutes each) show the performance and reliability of our framework.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Complaints about advertising in Australia have been on the increase in recent years under the stewardship of the new industry self-regulatory body, the Advertising Standards Board. This study utilises clustering analyses based on geodemographic and psychographic data to present a concrete profile of complainants about advertising in Australia. The findings indicate that the advertising publics must shoulder responsibility and ensure that greater care is taken to include all members of Australian society in the current complaints
process and that this inclusivity will ensure that the highest possible standards are the norms of the industry.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Practicing teachers and principals in selected Government schools in Victoria provided data on their levels of emotional intelligence and teacher efficacy beliefs. The data supported the theoretical expectation of a linkage between emotional intelligence and teacher self efficacy. Regression analyses showed that neither gender nor age moderated this relationship. However length of teaching experience and current status add significant direct effects on predicting teacher self efficacy but did not moderate the relationship between emotional intelligence and teacher self efficacy. These findings are significant as this now demonstrates a relationship between levels of emotional intelligence in teachers, their self efficacy beliefs and teacher effectiveness.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The current study investigated the relationship between career-related mentoring, psychosocial mentoring, business success, and self-esteem in participants of a program that was designed to assist in the establishment of a new business. Seventy-seven protégés and their matched mentors were included in the study. A comparison of mentor and protégé perceptions revealed that mentors considered themselves to provide higher levels of psychosocial support than did the protégés. Protégé perceptions of business success were predicted by the frequency of mentor contact and the level of career-related support provided by their mentor.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Aims: University student alcohol misuse is a considerable problem. Alcohol expectancy research has contributed significantly to our understanding of problem drinking in young adults. Most of this research has investigated positive expectancy alone. The current study utilized two measures of alcohol expectancy, the alcohol expectancy questionnaire (AEQ) and the drinking expectancy profile [consisting of the drinking expectancy questionnaire (DEQ) and the drinking refusal self-efficacy questionnaire] to predict severity of alcohol dependence, frequency of drinking, and the quantity of alcohol consumed per occasion. Methods: Measures of drinking behaviour and alcohol expectancy were completed by 174 undergraduate university students. Results: Positive alcohol expectancy factors accounted for significant variance in all three drinking indices, with the DEQ adding additional variance to AEQ scores on frequency and severity of alcohol dependence indices. Negative expectancy did not add incremental variance to the prediction of drinking behaviour in this sample. Drinking refusal self-efficacy and dependence beliefs added additional variance over positive and negative expectancies in the prediction of all three drinking parameters. Conclusions: Positive expectancy and drinking refusal self-efficacy were strongly related to university student drinking. The incorporation of expectancy as a means of informing prevention approaches in tertiary education shows promise.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

A Self-Assessment Manual (SAM) for early childhood practitioners has been developed around the previously reported framework (Raban, Waniganayake, Deans, Brown & Reynolds, 2003a), and this has been piloted in a number of early childhood settings. When engaging in self reflection using SAM, practitioners collaborate with mentors from the Early Childhood Consortium Victoria (ECCV) to consider their past, present and future professional experiences. This process empowers practitioners to critically examine their current practice and plan for their future professional development in a more systematic way. SAM is seen here to serve dual purposes: on the one hand, it is an evaluative instrument that can direct professional development of individual practitioners. On the other hand, it is a research tool aimed at identifying theoretical assumptions underpinning professional practice, and allows a longitudinal approach to mapping professional growth and development. Either way, it has the potential to enhance the quality of early childhood experiences for preschool children regardless of the settings in which they may find themselves. This paper presents a formative evaluation of this work and discusses its potential for professional development planning.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

This paper explores psychotherapeutic themes and modes of thought emerging in interviews with mothers and daughters participating in a cross-generational study of young women 'on the margins'. The focus of the discussion is two-fold. First it discusses current theoretical debates concerning the ascendancy of psychotherapeutic modes of constituting the self, and argues that we require closer attention to the gendered and differentiated ways in which these are registered and articulated. Second, it considers the significance of 'happiness' and the ways in which pairs of mothers and daughters draw upon a repertoire of psychotherapeutic discourses to represent their relation to schooling, self, family, and work. It concludes with some speculative observations about the significance of attending to the psychotherapeutic turn for understanding contemporary femininity, the desire for openness as a measure of a good relationship (and of democracy), and contemporary aspirations of happiness.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Research has indicated that having a sexually transmitted infection (STI) such as genital herpes and genital human papilloma virus (HPV) can have a negative impact on an individual's sexuality. The current study was designed to evaluate the effect of STI status, relationship status, and disclosure status on various dimensions of sexual self-concept. A questionnaire that evaluated the above variables was completed by 117 individuals with genital herpes, 82 individuals with HPV, and 75 individuals with no STI. The results demonstrated that having herpes or HPV had a significant negative impact on aspects of sexual self-concept. It does not appear that an individual's relationship status is a factor associated with the impact of having an STI on the sexual self-concept. Respondents who had disclosed their STI to their partners, however, had significantly more positive feelings about aspects of their sexual self-concept than those who had not disclosed their STI to their partners. The implications of these research findings for health practitioners are discussed.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Objective: To explore trends in the practice of mother-infant psychotherapy among perinatal psychiatry clinicians based in Melbourne.Methods: A cross-sectional survey with a purpose designed self-report questionnaire was used to assess the attitudes and practices of 47 perinatal and infant psychiatry clinicians in their use and understanding of mother-infant psychotherapy.Results: Seventy per cent of clinicians in this field of psychotherapy who responded to the questionnaire subscribe to a psychodynamic model, although cognitive behavioural models are also used. The interventions were mostly used in conjunction with other interventions, would be more accurately described as 'parent-infant psychotherapy', and non-psychiatrists in the area tended to be more likely to be formally trained in psychotherapy, but only 4% were formally trained in specific mother-infant psychotherapy. There was a unanimous request for further clinical training in this area.Conclusions: The emerging field of perinatal psychiatry needs to develop coherent therapeutic models and conduct outcome trials on specific interventions. Specific trainings in these models, in assessment and in diagnostic frameworks are required to enhance clinical efficacy, for research and service development purposes.