991 resultados para 207-1258
Resumo:
The preparation of a series of nickel dichloride complexes with bulky diphosphinomethane chelate ligands R2PCH2PR′2 is reported. Reaction with the appropriate Grignard reagent leads to the corresponding dimethyl and dibenzyl complexes. Cationic monomethyl and mono-η3-benzyl complexes are generated from these dialkyl complexes by protonation with [H(OEt2)2]+[B(3,5-(CF3)2C6H3)4]−, while the complex [(dtbpm κ2P)Ni(η3-CH(CH2Ph)Ph]+[B(3,5-(CF3)2C6H3)4]−is obtained from protonation of the Ni(0) olefin complex (dtbpm-κ2P)N(η2-trans-stilbene). Crystal structures of examples of dichlorides, dimethyl, dibenzyl, cationic methyl, and cationic η3-benzyl complexes are reported. Solutions of the cations polymerize ethylene under mild conditions and without the necessity of an activating agent, to form polyethylene having high molecular weights and low degrees of chain branching. In comparison to the Ni methyl cations, the η3-benzyl cation complexes are more stable and somewhat less active but still very efficient in C2H4 polymerization. The effect on the resulting polyethylene of varying the substituents R, R′ on the phosphine ligand has been examined, and a clear trend for longer chain PE with less branching in the presence of more bulky substituents on the diphosphine has been found. Density functional calculations have been used to examine the rapid suprafacial η3 to η3 haptotropic shift processes of the[(R2PCH2PR′2)Ni] fragment and the η3−η1 change of the coordination mode of the benzyl group required for polymerization in those cations.
Resumo:
There is a continued need to consider ways to prevent early adolescent engagement in a variety of harmful risk-taking behaviours for example, violence, road-related risks and alcohol use. The current prospective study examined adolescents’ reports of intervening to try and stop friends’ engagement in such behaviours among 207 early adolescents (mean age = 13.51 years, 50.1% females). Findings showed that intervening behaviour after three months was predicted by the confidence to intervene which in turn was predicted by student and teacher support although not parental support. The findings suggest that the benefits of positive relationship experiences might extend to the safety of early adolescent friendship groups particularly through the development of confidence to try and stop friends’ risky and dangerous behaviours. Findings from the study support the important role of the school in creating a culture of positive adolescent behaviour whereby young people take social responsibility.
Resumo:
In Mango Boulevard Pty Ltd v Spencer [2010] QCA 207, a self-executing order had been made in consequence of continuing default by parties to the proceedings in meeting their disclosure obligations. The case involved several questions about the construction and implications of the self-executing order. This note focuses on the aspects of the case relating to that order.
Resumo:
The Cape York Welfare Reform (‘CYWR’) trial was due to expire at the end of 2011. In October 2011, the Queensland Government voted to extend the trial until the end of 2013. In November 2011, the Federal Minister for Indigenous Affairs announced changes to the Social Security (Administration) Act 1999 (Cth) that will extend another similar welfare reform, the School Enrolment and Attendance through Welfare Reform Measure (‘SEAM’), throughout other parts of Australia. This article examines the CYWR with reference to the Racial Discrimination Act 1975 (Cth) (‘RDA’), using the data available in the publications from the Family Responsibilities Commission (‘FRC’).It finds no clear evidence that the reforms have been effective in improving social conditions thus far and, as such, serious concerns as to whether the CYWR breaches the RDA.
Resumo:
This chapter will first consider the rationale for a transition pedagogy for first and final year law students. It then discusses the elements of a transition pedagogy for both years, noting the synergies and differences between programs designed to assist transition into and out of a law degree. In doing so, the authors attempt to explore the extent to which the first year curriculum principles identified by Sally Kift under an Australian Learning and Teaching Council (ALTC) Senior Fellowship may also be applied to the final year university experience. During the course of the discussion, examples are drawn from universities and Law Schools in Australia and internationally which seek to address these imperatives...
Resumo:
The Comprehensive Australian Study of Entrepreneurial Emergence (CAUSEE) is the largest study of new firm creation ever undertaken in Australia. The project provides an exciting opportunity to fundamentally improve our understanding of independent entrepreneurship in Australia by studying factors that initiate, hinder and facilitate the process of emergence of new economic activities and organisations. The longitudinal project has followed a large random sample of nascent firms (n=625) and young firms (n=559) over a six year period. NFs are on-going start-up efforts while YFs are already established but less than four years old. The study also includes a comparison group of non-founders and over-samples of over 100 high potential start-ups in each category. The CAUSEE dataset file contains hundreds of variables throughout 5 waves of data collection. Extensive documentation on the dataset is available in the related handbook. The CAUSEE project has received significant external funding from the Australian Research Council (DP0666616 and LP0776845); National Australia Bank; BDO Australia, and the Australian Government Department of Industry, Innovation and Science.
Resumo:
Injury is the leading cause of death among young people, and involvement in health risk behaviors, such as alcohol use and transport-related risks, is related to increased risk for injury. Effective health promotion programs for adolescents focus on multiple levels, including relationships with peers and parents, student knowledge, behavior and attitudes, and school-level factors such as school connectedness. This study describes the pilot evaluation of a comprehensive, multi-level injury prevention program for 13-14 year old adolescents, targeting change in injury associated with transport and alcohol risks. The program, called Skills for Preventing Injury in Youth (SPIY), incorporates two primary elements: an 8-week, teacher delivered attitude and behavior change curriculum with peer protection and first aid messages; and professional development for program teachers focusing on strategies to increase students’ connectedness to school. Five Australian high schools were recruited for the pilot evaluation research, with three being assigned to receive intervention components and two assigned as curriculum-as-usual controls. In the intervention schools, 118 Year 8 students participated in surveys at baseline, with 105 completing surveys at follow up, six months following the intervention. In the control schools, 196 Year 8 students completed surveys at baseline and 207 at follow up. Survey measures included self-reported injury, risk taking behavior and school connectedness. Results showed that students in the control schools were significantly more likely to report riding bikes without helmets, riding with dangerous drivers, having driven cars on the road, and using alcohol six months after the program, while the intervention group showed no such increase in these behaviors. Additionally, students in the control schools were significantly more likely to report having had pedestrian-related injuries at follow up than they were at the baseline measurement, while intervention school students showed no change. There was also a trend observed in terms of a decrease in bicycle related injuries among intervention school students, compared with a slight increasing trend in bicycle injuries among control students. Overall, scores on the school connectedness scale decreased significantly from baseline to follow up for both intervention and control students, however measurement limitations may have impacted on results relating to students’ connectedness. Overall, the SPIY program has shown promising results in regards to prevention of students’ health risk behavior and injuries. Evidence suggests that the curriculum component was important; however there was limited evidence to suggest that teacher training in school connectedness strategies contributed to these promising results. While school connectedness may be an important factor to target in risk and injury prevention programs, programs may need to incorporate whole-of-school strategies or target a broader range of teachers than were selected for the current research.
Resumo:
Background: The accurate evaluation of physical activity levels amongst youth is critical for quantifying physical activity behaviors and evaluating the effect of physical activity interventions. The purpose of this review is to evaluate contemporary approaches to physical activity evaluation amongst youth. Data sources: The literature from a range of sources was reviewed and synthesized to provide an overview of contemporary approaches for measuring youth physical activity. Results: Five broad categories are described: self-report, instrumental movement detection, biological approaches, direct observation, and combined methods. Emerging technologies and priorities for future research are also identified. Conclusions: There will always be a trade-off between accuracy and available resources when choosing the best approach for measuring physical activity amongst youth. Unfortunately, cost and logistical challenges may prohibit the use of "gold standard" physical activity measurement approaches such as doubly labelled water. Other objective methods such as heart rate monitoring, accelerometry, pedometry, indirect calorimetry, or a combination of measures have the potential to better capture the duration and intensity of physical activity, while self-reported measures are useful for capturing the type and context of activity.
Resumo:
The decline of large coevolved frugivorous species within fragmented habitats can have an effect on ecological processes, for example, seed dispersal and germination. It is therefore necessary for more resilient species to ensure essential processes are maintained within the system. This study investigates the influence of two rodent species, Melomys cervinipes (Fawn-footed Melomys) and Rattus fuscipes (Bush Rat), on the germination process of rainforest fruits. Both species are endemic to north Queensland rainforest and commonly found in fragmented habitats in high densities. We found in 85% of fruit species tested, rodent feeding increased seed germination rate by a factor of 3.5. Our results suggest that rodents can play a significant role in enhancing germination rates of fruits in the tropical rainforest of far north Queensland.
Resumo:
Timed-release cryptography addresses the problem of “sending messages into the future”: information is encrypted so that it can only be decrypted after a certain amount of time, either (a) with the help of a trusted third party time server, or (b) after a party performs the required number of sequential operations. We generalise the latter case to what we call effort-release public key encryption (ER-PKE), where only the party holding the private key corresponding to the public key can decrypt, and only after performing a certain amount of computation which may or may not be parallelisable. Effort-release PKE generalises both the sequential-operation-based timed-release encryption of Rivest, Shamir, and Wagner, and also the encapsulated key escrow techniques of Bellare and Goldwasser. We give a generic construction for ER-PKE based on the use of moderately hard computational problems called puzzles. Our approach extends the KEM/DEM framework for public key encryption by introducing a difficulty notion for KEMs which results in effort-release PKE. When the puzzle used in our generic construction is non-parallelisable, we recover timed-release cryptography, with the addition that only the designated receiver (in the public key setting) can decrypt.
Resumo:
Privacy is an important component of freedom and plays a key role in protecting fundamental human rights. It is becoming increasingly difficult to ignore the fact that without appropriate levels of privacy, a person’s rights are diminished. Users want to protect their privacy - particularly in “privacy invasive” areas such as social networks. However, Social Network users seldom know how to protect their own privacy through online mechanisms. What is required is an emerging concept that provides users legitimate control over their own personal information, whilst preserving and maintaining the advantages of engaging with online services such as Social Networks. This paper reviews “Privacy by Design (PbD)” and shows how it applies to diverse privacy areas. Such an approach will move towards mitigating many of the privacy issues in online information systems and can be a potential pathway for protecting users’ personal information. The research has also posed many questions in need of further investigation for different open source distributed Social Networks. Findings from this research will lead to a novel distributed architecture that provides more transparent and accountable privacy for the users of online information systems.