179 research outputs found

    Boundary Contributions Using Fermion Pair Deformation

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    Continuing the study of boundary BCFW recursion relation of tree level amplitudes initiated in \cite{Feng:2009ei}, we consider boundary contributions coming from fermion pair deformation. We present the general strategy for these boundary contributions and demonstrate calculations using two examples, i.e, the standard QCD and deformed QCD with anomalous magnetic momentum coupling. As a by-product, we have extended BCFW recursion relation to off-shell gluon current, where because off-shell gluon current is not gauge invariant, a new feature must be cooperated.Comment: 26 pages, 4 figure

    The relationship between structural game characteristics and gambling behavior: a population-level study

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    The aim of this study was to examine the relationship between the structural characteristics and gambling behavior among video lottery terminal (VLT) gamblers. The study was ecological valid, because the data consisted of actual gambling behavior registered in the participants natural gambling environment without intrusion by researchers. Online behavioral tracking data from Multix, an eight game video lottery terminal, were supplied by Norsk-Tipping (the state owned gambling company in Norway). The sample comprised the entire population of Multix gamblers (N = 31,109) who had gambled in January 2010. The individual number of bets made across games was defined as the dependent variable, reward characteristics of a game (i.e., payback percentage, hit frequency, size of winnings and size of jackpot) and bet characteristics of a game (i.e., range of betting options and availability of advanced betting options) served as the independent variables. Control variables were age and gender. Two separate cross-classified multilevel random intercepts models were used to analyze the relationship between bets made, reward characteristics and bet characteristics, where the number of bets was nested within both individuals and within games. The results show that the number of bets is positively associated with payback percentage, hit frequency, being female and age, and negatively associated with size of wins and range of available betting options. In summary, the results show that the reward characteristics and betting options explained 27 % and 15 % of the variance in the number of bets made, respectively. It is concluded that structural game characteristics affect gambling behavior. Implications of responsible gambling are discussed

    Understanding within-session loss-chasing: an experimental investigation of the impact of stake size on cognitive control

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    Loss-chasing is a central feature of problematic gambling, yet it remains a poorly conceived and understood concept. Loss-chasing is believed to stem from an ero- sion of cognitive control when gambling. The opportunity to gamble at significantly dis- parate stake sizes on a gambling activity is considered to be a risk factor for loss-chasing. This study investigated the impact of gambling at disparate stake sizes on executive processes integral to maintaining cognitive control when gambling, namely response inhibition and reflection impulsivity. Frequent adult non-problem gamblers (n = 32) participated in a repeated measures experiment; and gambled at three disparate stake sizes (£20, £2 and no stake per bet) on a simulated gambling task. Participants’ response inhibition performance and reflection impulsivity levels after gambling at various stake sizes were compared via a go/no-go task and information sampling task, respectively. Quality of decision-making i.e. the evaluation of available information to make probability judgements was impaired after gambling at higher stakes in comparison to lower stakes, indicating an increase in reflection impulsivity. No effect on response inhibition was observed. Although exploratory, this suggests that the opportunity for participants to substantially increase stake size on a gambling activity may be a risk factor for impaired cognitive performance when gambling, and perhaps create vulnerability for within-session loss-chasing in some players. Keywords Problem gambling - Cognitive control - Loss-chasing - Response inhibition - Reflection impulsivit

    The relationship between gambling event frequency, motor response inhibition, arousal, and dissociative experience

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    Speed of play has been identified as a key structural characteristic in gambling behaviour, where games involving higher playing speeds enhance the experience of gambling. Of interest in the present study is the consistent finding that games with higher event frequencies are preferred by problem gamblers and are associated with more negative gambling outcomes, such as difficulty quitting the game and increased monetary loss. The present study investigated the impact of gambling speed of play on executive control functioning, focusing on how increased speeds of play impact motor response inhibition, and the potential mediating role arousal and dissociative experience play in this relationship. Fifty regular non-problem gamblers took part in a repeated-measures experiment where they gambled with real money on a simulated slot machine across five speed of play conditions. Response inhibition was measured using an embedded Go/No-Go task, where participants had to withhold motor responses, rather than operating the spin button on the slot machine when a specific colour cue was present. Results indicated that response inhibition performance was significantly worse during faster speeds of play, and that the role of arousal in this relationship was independent of any motor priming affect. The implications of these findings for gambling legislation and gambling harm-minimisation approaches are discussed

    Prime movers : mechanochemistry of mitotic kinesins

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    Mitotic spindles are self-organizing protein machines that harness teams of multiple force generators to drive chromosome segregation. Kinesins are key members of these force-generating teams. Different kinesins walk directionally along dynamic microtubules, anchor, crosslink, align and sort microtubules into polarized bundles, and influence microtubule dynamics by interacting with microtubule tips. The mechanochemical mechanisms of these kinesins are specialized to enable each type to make a specific contribution to spindle self-organization and chromosome segregation

    Comparison of sapwood invasion by three Phytophthora spp.in different hosts

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    Many Phytophthora spp. have recently been isolated from native vegetation in Western Australia. As their pathogenicity is often unknown, it is not possible to provide advice to land managers on the impact of site infestation on native plants and how these infestations should be managed. We describe a rapid screening method based on sapwood invasion that has been used to compare the pathogenicity of Phytophthora arenaria, P. cinnamomi and P. multivora. Radial invasion into the xylem of six banksias and three eucalypts was assessed in an excised branch assay in summer and winter. Branches were wound inoculated and invasion was assessed by plating from a strip of tissue cut across the stem at the inoculation point and at 40 mm above and below. A symptomless infection had established in both the bark and sapwood within 6 days. P. arenaria was only isolated from the strip of tissue at the inoculation point. P. cinnamomi was isolated from the sapwood of Banksia attenuata, B. burdettii, B. menziesii and B. speciosa 40 mm above or below the inoculation point in some experiments. P. multivora was isolated from B. speciosa 40 mm below the inoculation point in one experiment. Hyphae of both species were seen in both ray parenchyma cells and xylem vessels. The invasiveness of the Phytophthora spp. was compared on the two groups of hosts using scores for sapwood invasion at the inoculation point. For banksias, P. cinnamomi and P. multivora had significantly higher invasion scores on banksias than P. arenaria but were not significantly different to one another. There was no significant difference between the three Phytophthora spp. on the eucalypt hosts. Assessing sapwood invasion provides a rapid, inexpensive and biologically meaningful way of screening the many Phytophthora spp. that have been isolated from native vegetation

    Comorbidity and dementia: a scoping review of the literature.

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    BACKGROUND: Evidence suggests that amongst people with dementia there is a high prevalence of comorbid medical conditions and related complaints. The presence of dementia may complicate clinical care for other conditions and undermine a patient's ability to manage a chronic condition. The aim of this study was to scope the extent, range and nature of research activity around dementia and comorbidity. METHODS: We undertook a scoping review including all types of research relating to the prevalence of comorbidities in people with dementia; current systems, structures and other issues relating to service organisation and delivery; patient and carer experiences; and the experiences and attitudes of service providers. We searched AMED, Cochrane Library, CINAHL, PubMed, NHS Evidence, Scopus, Google Scholar (searched 2012, Pubmed updated 2013), checked reference lists and performed citation searches on PubMed and Google Scholar (ongoing to February 2014). RESULTS: We included 54 primary studies, eight reviews and three guidelines. Much of the available literature relates to the prevalence of comorbidities in people with dementia or issues around quality of care. Less is known about service organisation and delivery or the views and experiences of people with dementia and their family carers. There is some evidence that people with dementia did not have the same access to treatment and monitoring for conditions such as visual impairment and diabetes as those with similar comorbidities but without dementia. CONCLUSIONS: The prevalence of comorbid conditions in people with dementia is high. Whilst current evidence suggests that people with dementia may have poorer access to services the reasons for this are not clear. There is a need for more research looking at the ways in which having dementia impacts on clinical care for other conditions and how the process of care and different services are adapting to the needs of people with dementia and comorbidity. People with dementia should be included in the debate about the management of comorbidities in older populations and there needs to be greater consideration given to including them in studies that focus on age-related healthcare issues

    Parents’ Promotion of Psychological Autonomy, Psychological Control, and Mexican–American Adolescents’ Adjustment

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    Mexican–American adolescents are at an elevated risk for adjustment difficulties. In an effort to identify parenting practices that can affect the adjustment of Mexican–American youth, the current study examined parents’ promotion of psychological autonomy and parents’ psychological control as perceived by Mexican–American early adolescents, and explored their associations with adolescents’ adjustment in the context of acculturation. In 5th grade, 134 (54.5% female) Mexican–American adolescents reported on their acculturation level and the parenting practices of their mothers and fathers. In 5th and 7th grade, adolescents also reported on their depressive symptoms, number of delinquent friends, and self-worth. Perceptions of promotion of psychological autonomy and of psychological control were positively correlated. However, perceptions of more promotion of psychological autonomy and of less psychological control predicted fewer depressive symptoms 2 years later. Perceptions of more promotion of psychological autonomy also predicted fewer delinquent friends two years later. Finally, perceptions of more promotion of psychological autonomy predicted higher self-worth only among less acculturated adolescents. The study underscores the roles that promotion of psychological autonomy and psychological control may play in Mexican–American children’s well-being during early adolescence
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