266 resultados para MCDONALD
Resumo:
Samples of sea water contain phytoplankton taxa in varying amounts, and marine scientists are interested in the relative abundance of each taxa. Their relative biomass can be ascertained indirectly by measuring the quantity of various pigments using high performance liquid chromatography. However, the conversion from pigment to taxa is mathematically non trivial as it is a positive matrix factorisation problem where both matrices are unknown beyond the level of initial estimates. The prior information on the pigment to taxa conversion matrix is used to give the problem a unique solution. An iteration of two non-negative least squares algorithms gives satisfactory results. Some sample analysis of data indicates prospects for this type of analysis. An alternative more computationally intensive approach using Bayesian methods is discussed.
Resumo:
In this paper we present truncated differential analysis of reduced-round LBlock by computing the differential distribution of every nibble of the state. LLR statistical test is used as a tool to apply the distinguishing and key-recovery attacks. To build the distinguisher, all possible differences are traced through the cipher and the truncated differential probability distribution is determined for every output nibble. We concatenate additional rounds to the beginning and end of the truncated differential distribution to apply the key-recovery attack. By exploiting properties of the key schedule, we obtain a large overlap of key bits used in the beginning and final rounds. This allows us to significantly increase the differential probabilities and hence reduce the attack complexity. We validate the analysis by implementing the attack on LBlock reduced to 12 rounds. Finally, we apply single-key and related-key attacks on 18 and 21-round LBlock, respectively.
Resumo:
A quasi-experimental design (N=517) was used to investigate the effect on audience response to a supported charity if corporate support is featured in an advertisement. The results indicate that corporate support of a charity appears not to influence audience attitudes and donation intentions for the charity. A small portion of the audience may be motivated to donate when learning of a large corporate donation to the charity. The level of individual's favourability for the charity was the strongest predictor of their attitudes and intentions. Gender was also a predictor of more positive charity attitudes, with females reporting more positive attitudes than males for three of four charities. Managerial implications and areas for future research are discussed.
Resumo:
Trivium is a stream cipher candidate of the eStream project. It has successfully moved into phase three of the selection process under the hardware category. No attacks faster than the exhaustive search have so far been reported on Trivium. Bivium-A and Bivium-B are simplified versions of Trivium that are built on the same design principles but with two registers. The simplified design is useful in investigating Trivium type ciphers with a reduced complexity and provides insight into effective attacks which could be extended to Trivium. This paper focuses on an algebraic analysis which uses the boolean satisfiability problem in propositional logic. For reduced variants of the cipher, this analysis recovers the internal state with a minimal amount of keystream observations.
Resumo:
The purpose of this study was to evaluate the validity and inter-rater reliability of the Observation System for Recording Activity in Children: Youth Sports (OSRAC:YS). Children (N=29) participating in a parks and recreation soccer program were observed during regularly scheduled practices. Physical activity (PA) intensity and contextual factors were recorded by momentary time-sampling procedures (10-sec observe, 20-sec record). Two observers simultaneously observed and recorded children's PA intensity, practice context, social context, coach behavior, and coach proximity. Inter-rater reliability was based on agreement (Kappa) between the observer's coding for each category, and the Intraclass Correlation Coefficient (ICC) for percent of time spent in MVPA. Validity was assessed by calculating the correlation between OSRAC:YS estimated and objectively measured MVPA. Kappa statistics for each category demonstrated substantial to almost perfect inter-observer agreement (Κappa = 0.67 to 0.93). The ICC for percent time in MVPA was 0.76 (95% C.I. = 0.49 - 0.90). A significant correlation (r = 0.73) was observed for MVPA recorded by observation and MVPA measured via accelerometry. The results indicate the OSRAC:YS is a reliable and valid tool for measuring children's PA and contextual factors during a youth soccer practice.
Resumo:
Background Parents play a significant role in shaping youth physical activity (PA). However, interventions targeting PA parenting have been ineffective. Methodological inconsistencies related to the measurement of parental influences may be a contributing factor. The purpose of this article is to review the extant peer-reviewed literature related to the measurement of general and specific parental influences on youth PA. Methods A systematic review of studies measuring constructs of PA parenting was conducted. Computerized searches were completed using PubMed, MEDLINE, Academic Search Premier, SPORTDiscus, and PsycINFO. Reference lists of the identified articles were manually reviewed as well as the authors' personal collections. Articles were selected on the basis of strict inclusion criteria and details regarding the measurement protocols were extracted. A total of 117 articles met the inclusionary criteria. Methodological articles that evaluated the validity and reliability of PA parenting measures (n=10) were reviewed separately from parental influence articles (n=107). Results A significant percentage of studies used measures with indeterminate validity and reliability. A significant percentage of articles did not provide sample items, describe the response format, or report the possible range of scores. No studies were located that evaluated sensitivity to change. Conclusion The reporting of measurement properties and the use of valid and reliable measurement scales need to be improved considerably.
Resumo:
Sexuality is a subject that has been, at best, marginal in the significant body of literature that has examined gender and mining in contemporary Western nations. This is despite the fact that academics have circled, if not almost bumped into the topic in closely related discussions of hegemonic masculinity and mining work, and of patriarchal familial relations and mining communities. This scholarship has documented what has been and remains women’s primary relationship to mining—that is, as a “mining wife.” How patriarchal relations are manifest in and emerge from this state of affairs has been critiqued with research on the gendered implications of housing arrangements in mining towns, the division of household labor, changing shift-work mining rosters, and the gendered consequences of strikes and mine closures (Williams 1981; Gibson 1992; Gibson-Graham 1996; Rhodes 2005; McDonald, Mayes, and Pini 2012). Despite the centrality of the heterosexual relationship—and indeed heteronormativity—to these discussions, scholars of gender and mining have had little to say on the subject of sexuality. In response to this lacuna, this chapter takes an exploratory lens to the subject of sexuality and the mining industry. We approach the task from the perspective that the mining industry is gendered as masculine. That is, definitions of mining mobilize around masculinized notions of physicality, technical competence with machinery, and strength, as well as emphasize the harshness and dirtiness of the work (Mayes and Pini 2010).