980 resultados para Restricted three-body problem


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The learning experiences of first-year engineering students to a newly implemented engineering problem-based learning (PBL) curriculum is reported here, with an emphasis on student approaches to learning. Ethnographic approaches were used for data collection and analysis. This study found that student learning in a PBL team in this setting was mainly influenced by the attitudes, behaviour and learning approaches of the student members in that team. Three different learning cultures that emerged from the analysis of eight PBL teams are reported here. They are the finishing culture, the performing culture and the collaborative learning culture. It was found that the team that used a collaborative approach to learning benefited the most in this PBL setting. Students in this team approached learning at a deep level. The findings of this study imply that students in a problem-based, or project-based, learning setting may not automatically adopt a collaborative learning culture. Hence, it is important for institutions and teachers to identify and consider the factors that influence student learning in their particular setting, provide students with necessary tools and ongoing coaching to nurture deep learning approaches in PBL teams.

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This paper addresses the problem of markerless tracking of a human in full 3D with a high-dimensional (29D) body model Most work in this area has been focused on achieving accurate tracking in order to replace marker-based motion capture, but do so at the cost of relying on relatively clean observing conditions. This paper takes a different perspective, proposing a body-tracking model that is explicitly designed to handle real-world conditions such as occlusions by scene objects, failure recovery, long-term tracking, auto-initialisation, generalisation to different people and integration with action recognition. To achieve these goals, an action's motions are modelled with a variant of the hierarchical hidden Markov model The model is quantitatively evaluated with several tests, including comparison to the annealed particle filter, tracking different people and tracking with a reduced resolution and frame rate.

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This paper focuses on the problem of tracking people through occlusions by scene objects. Rather than relying on models of the scene to predict when occlusions will occur as other researchers have done, this paper proposes a linear dynamic system that switches between two alternatives of the position measurement in order to handle occlusions as they occur. The filter automatically switches between a foot-based measure of position (assuming z = Q) to a head-based position measure (given the person's height) when an occlusion of the person's lower body occurs. No knowledge of the scene or its occluding objects is used. Unlike similar research [2, 14], the approach does not assume a fixed height for people and so is able to track humans through occlusions even when they change height during the occlusion. The approach is evaluated on three furnished scenes containing tables, chairs, desks and partitions. Occlusions range from occlusions of legs, occlusions whilst being seated and near-total occlusions where only the person's head is visible. Results show that the approach provides a significant reduction in false-positive tracks in a multi-camera environment, and more than halves the number of lost tracks in single monocular camera views.

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Modern datasets are becoming heterogeneous. To this end, we present in this paper Mixed- Variate Restricted Boltzmann Machines for simultaneously modelling variables of multiple types and modalities, including binary and continuous responses, categorical options, multicategorical choices, ordinal assessment and category-ranked preferences. Dependency among variables is modeled using latent binary variables, each of which can be interpreted as a particular hidden aspect of the data. The proposed model, similar to the standard RBMs, allows fast evaluation of the posterior for the latent variables. Hence, it is naturally suitable for many common tasks including, but not limited to, (a) as a pre-processing step to convert complex input data into a more convenient vectorial representation through the latent posteriors, thereby oering a dimensionality reduction capacity, (b) as a classier supporting binary, multiclass, multilabel, and label-ranking outputs, or a regression tool for continuous outputs and (c) as a data completion tool for multimodal and heterogeneous data. We evaluate the proposed model on a large-scale dataset using the world opinion survey results on three tasks: feature extraction and visualization, data completion and prediction.

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This paper is a conceptual and methodological review of the literature on the impact of TV on preschoolers' weight status. A systematic search, of papers published between January 1995 and January 2010, identified twenty-six relevant studies. Fifteen of these were cross-sectional in design and eleven adopted a prospective design; a positive association between hours of TV and child adiposity was found in all but three studies. Although assessed in a limited number of studies, diet may mediate the relationship between TV viewing and BMI. Another likely mediator may be the content of TV programs watched; only three studies examined this association and findings were inconsistent. Our review revealed that research examining mediating effects is limited, focusing more on simple cross-sectional or prospective relationships between TV habits and child body mass index. Further investigation of the mechanisms by which TV viewing affects preschool weight gain is needed.

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We assessed intergenerational differences in food, physical activity, and body size perceptions among refugees and migrants from the Horn of Africa living in Victoria, Australia. We used a qualitative design and obtained data from 48 participants (18 individual interviews; 3 semistructured focus groups). Three major themes emerged: (a) food and physical activity, (b) preference of body size and social expectations, and (c) perceived consequences of various body sizes. For parents, large body size was perceived to equate with being beautiful and wealthy; slimness was associated with chronic illness and poverty. Parents adopted strategies that promoted weight gain in children. These included tailored food practices and restricting children’s involvement in physical activity. For young people, slimness was the ideal body size endorsed by their peers, and they adopted strategies to resist parental pressure to gain weight. Obesity-prevention programs in this subpopulation need to adopt a multigenerational approach.

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American bison grow a thick coat of fibres which assists them to withstand severe climatic conditions. Bison fibre was traditionally used in textiles by native North Americans. This study aimed to quantify the production, fibre attributes and dehairing processing of bison fibre produced from bison grazed in north-eastern Victoria. Three age/sex classes were sampled (n = 16) at seven body positions in spring. The fibre growing area was measured. Fibre was tested for diameter distribution, clean washing yield, proportion of fine fibres <36µm and fine fibre length, and processed by cashmere dehairing. Bison were 12 years of age, liveweights 160450 kg and had mean fibre growing area of 1.4 m2. They produced an average 1184 g (range 5301640 g) of fine fibre with mean fibre diameter 18.5µm, clean washing yield 76.5%, wax content 9.8%, suint content 14.5%, clean fine fibre yield 56.4%, fine fibre length 37 mm and fibre curvature was 93/mm. Mid-side fibre had a crimp frequency of 6.5/cm and mean resistance to compression of 6.6 kPa. Fibre had a tenacity of 8.7 cN/tex and an extension of 39.3%. Restricted maximum likelihood mixed model analysis showed age/sex class and sampling site significantly affected all fibre attributes. Finer and longer fibre was produced in anterior sites and in younger bison. Fibre curvature declined 5.3°/mm for each 1-µm increase in mean fibre diameter. Dehaired fibre had a mean fibre diameter of 17.8 µm and mid-length of 28 mm, suitable for woollen spinning. The production by bison of coats containing significant amounts of fibre indicates that careful harvesting of fibre could form an important source of income in bison enterprises.

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We administered a paper-and-pencil questionnaire to 133 female and 99 male Japanese high school students 13–18 years old (M = 15.9, SD = 1.57) from the Kansai area to examine cultural influences on their body image and body change behaviours. Our aim was to ascertain the independent and combined influences from traditional Japanese, modern Japanese, and Western values. Cluster analyses identified four ‘acculturative’ groups: ‘anti-modern’, ‘traditional’, ‘pro-modern/anti-traditional’, and ‘pro-Western/anti-Japanese’. Pro-modern and pro-Western adolescents were most dissatisfied with their bodies, and pro-Western adolescents were also most likely to attempt weight loss. The results demonstrate the value of assessing cultural interactions in Japan along three dimensions.

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 Problem based learning has been implemented as a pedagogical tool world-wide across a range of health professions since its inception at McMaster University, Canada, in 1969 (Neville & Norman, 2007). In addition to enhancing knowledge and understanding it is also claimed that PBL develops communication skills, encourages teamwork, sharing of information and respect for others, furthers problem solving skills, and allows students to assume responsibility for their own learning (Wood, 2003). However, the cognitive outcomes of PBL and traditional pedagogy (based on didactic teaching) are similar and hence widespread adoption of PBL has been questioned (see Colliver, 2000). Criticisms of PBL include its resource hungry nature, requiring, as it does, experienced tutors to facilitate .learning across several clusters of students dealing with the same problem. Given the actual and anticipated increase in numbers of medical students in Australia other strategies that retain the advantages of PBL, while minimising the demands on faculty, should now be explored. This paper reports our experience with a modification of the traditional PBL approach, termed PBLplus. This innovation was trialled in a regional clinical school, attached to a hospital, with a group of 19 graduate entry students, who had completed an integrated Year 1 / 2 of the MBBS. PBLplus involved allocating students from the whole class to three task directed groups. Groups had specified assignments to complete to facilitate learning across the whole class. A tutor listened to student presentations and provided an interactive presentation. Hence use of tutors was made more efficient, and faculty input was more specialised.

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Motorbike riders are 34-times more likely to die in a crash compared to car drivers per km travelled (1). Such safety risks together with special skill requirements for the driver and much lower comfort compared to normal cars are the main reasons why motorbikes represent only a fraction of all vehicle sales in developed countries. Deakin University is developing a revolutionary cross-over fun vehicle with ultra low fuel consumption and emissions. This new vehicle generation combines the best of two worlds: the fun to drive, low cost, and small size of a scooter together with the safety, comfort and easiness to operate of a car. The result is a vehicle that is more fuel efficient than most cars or even scooters.

Various tilting cross over vehicles have been presented over the last decade that were trying to automate the tilting control of narrow vehicles to make them safer. Examples of these concepts are the Carver, Clever and in some way also the MP3 scooter from Piaggio. The problem with fully enclosed concepts like the Carver or Clever is that they require very complex and therefore also expensive tilting control systems so that the vehicles are not price competitive compared to low cost micro cars or even normal small cars. The MP3 on the other hand comes with a tilting control system which is only semi automatic so that typical car advantages - comprehensive safety features like crush zones, roll over protection, air bags, safety belts or comfort features like full weather protection including heating and cooling – can not be provided.

Deakin’s approach is quite different to the above mentioned concepts. The requirements were derived based on two different investigations: The first step was a critical evaluation of social trends and the second step was an in-depth benchmarking study of existing concepts which identified the typical strengths and weaknesses of these concepts. In a critical next step a new concept was created that addresses most of the weaknesses of existing tilting three-wheelers in a holistic approach by setting clear priority rankings for the vehicle targets, based on current trends. The priorities were set in the following order: Safety, Affordability, Fun and Efficiency (SAFE).

The key feature that enables an enclosed tilting vehicle is a fully automatic tilting control system. With an automatic tilting control system the driver does not need to put the feet on the ground to balance the vehicle when he stops, so the vehicle can be built with a full enclosure. This allows the implementation of typical car like safety features (seat belts, roll over structure, crush zones, air bags). The SafeRide™ tilting control system is a passive system that involves the driver’s balancing sense in its feedback control system. The vehicle has typical scooter like steering characteristics, where the steering is initiated through countersteering. Another safety critical design feature is the crush zone between the two front wheels which is not possible with only one front wheel or with the powertrain positioned between the front wheels, as the powertrain can’t absorb a lot of energy due to its structural stiffness and density. The passive tilting control system is quite simple and therefore makes the vehicle very affordable, an important factor for successful commercialisation.

Another advantage of integrating the human balancing senses in the feedback control of the tilting system is that the system kicks in slightly after the human balancing reacts. In some instances that can generate the typical adrenalin thrill known from riding a bike. This fun factor is quite common with many trend sports like mountain biking, surfing, roller-skating, snowboarding, or skateboarding. Some of these sports have seen very rapid growth only a short time after they have been invented. Utilising the human balancing system during driving also makes the vehicle safer as the adrenalin is produced after reaching a semi-stable driving condition that is controlled by the vehicles tilting control system, but before the vehicle reaches an unstable driving condition that can not be controlled by the vehicle but only (eventually) by the driver – if he has got the required driving skill and if he is alert enough.

Efficiency superior to most cars and scooters is achieved by the aerodynamics of a fully enclosed body structure in combination with the small frontal area of a typical scooter and the droplet shape enabled by the relatively wide front with 2 wheels and the very narrow tail with only one rear wheel. The passive tilting system also contributes to the extreme efficiency as the system only draws some small electrical power for the electronic control unit. Another feature is a low cost exhaust energy recovery system which is discussed in another paper.

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As part of video-stimulated post-lesson student interview studies of problem solving activity, Williams (2005, 2011) found successful problem solvers were optimistic. This study interrogates data from three students from a broader study: the role of optimism in collaborative problem solving and how to build it. The research question that focuses this study is “What associations exist between confidence, persistence, and optimism?” The question is explored both theoretically and empirically for the purpose of increasing understanding of the nature of optimistic problem solving activity by linking it to more familiar constructs. Students were progressively selected to further the interrogatory process. It was found that confidence and persistence did not necessarily occur together, and when they did, activity associated with these two characteristics was not sufficient for optimistic problem solving activity to occur. Perseverance was also required.

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The aim of this study was to determine the effects of high-glucose, high-fructose and high-sucrose diets on weight gain, liver lipid metabolism and gene expression of proteins involved with hepatic fat metabolism. Rats were fed a diet containing either 60% glucose, 60% fructose, 60% sucrose, or a standard chow for 28 days. Results indicated that high-fructose and high-sucrose diets were associated with higher mRNA levels of gene transcripts involved with fat synthesis; ACC, FAS and ChREBP, with no change in SREBP-1C mRNA. The protein level of ChREBP and SREBP1c was similar in liver homogenates from all groups, but were higher in nuclear fractions from the liver of high-fructose and high-sucrose fed rats. The mRNA level of gene transcripts involved with fat oxidation was the same in all three diets, whilst a high-fructose diet was associated with greater amount of mRNA of the fat transporter CD36. Despite the changes in mRNA of lipogenic proteins, the body weight of animals from each group was the same and the livers from rats fed high-fructose and high-sucrose diets did not contain more fat than control diet livers. In conclusion, changing the composition of the principal monosaccharide in the diet to a fructose containing sugar elicits changes in the level of hepatic mRNA of lipogenic and fat transport proteins and protein levels of their transcriptional regulators; however this is not associated with any changes in body weight or liver fat content.

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This study assessed the degree of equivalence between paper and Internet administration of three measures of panic and agoraphobia-related cognition and behavior: Body Sensations Questionnaire (BSQ), Agoraphobic Cognitions Questionnaire (ACQ), and Mobility Inventory (MI). Participants were 110 people with panic disorder who had registered for an Internet-based treatment program in Sweden (n = 54) or Australia (n = 56). Participants were randomly assigned to complete the questionnaires via the differing administration formats in a counterbalanced order. Results showed broadly equivalent psychometric properties across administrations, with strong significant intraclass correlations between them, and comparable Cronbach's alpha coefficients. A significant mean difference between administration formats was found for the BSQ only. In contrast to previous research, Internet administration did not generate higher scores than paper administration. No effect was found for order of administration. The findings suggest that each questionnaire can be validly administered via the Internet and used with confidence.

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This paper proposes an efficient solution algorithm for realistic multi-objective median shortest path problems in the design of urban transportation networks. The proposed problem formulation and solution algorithm to median shortest path problem is based on three realistic objectives via route cost or investment cost, overall travel time of the entire network and total toll revenue. The proposed solution approach to the problem is based on the heuristic labeling and exhaustive search technique in criteria space and solution space of the algorithm respectively. The first labels each node in terms of route cost and deletes cyclic and infeasible paths in criteria space imposing cyclic break and route cost constraint respectively. The latter deletes dominated paths in terms of objectives vector in solution space in order to identify a set of Pareto optimal paths. The approach, thus, proposes a non-inferior solution set of Pareto optimal paths based on non-dominated objective vector and leaves the ultimate decision to decision-makers for purpose specific final decision during applications. A numerical experiment is conducted to test the proposed algorithm using artificial transportation network. Sensitivity analyses have shown that the proposed algorithm is advantageous and efficient over existing algorithms to find a set of Pareto optimal paths to median shortest paths problems.

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Background:  Cognitive models of body dysmorphic disorder (BDD) suggest that beliefs and evaluations related to self-concept are central to the maintenance of the disorder, but such beliefs have received little empirical attention. This study examined the relative importance of contingent self-worth and self-ambivalence to BDD symptoms in comparison to their importance to obsessive–compulsive disorder and social phobia symptoms.

Method: 
The sample comprised 194 non-clinical participants (female, N = 148; males, N = 46) with a mean age of 24.70 years (standard deviation = 9.34). Participants were asked to complete a battery of self-report questionnaires. Results:  While significant relationships were found between the self-beliefs and symptoms of all three disorders, some specificity was found in the relationships.

Conclusions: 
Self-worth based upon appearance was most important in BDD, while contingent self-worth based on the approval of others was important in social phobia. Self-ambivalence was associated with each disorder. Implications and limitations are discussed.