Coding of visual space during motor preparation: approaching objects rapidly modulate corticospinal excitability in hand-centered coordinates

Defensive behaviors, such as withdrawing your hand to avoid potentially harmful approaching objects, rely on rapid sensorimotor transformations between visual and motor coordinates. We examined the reference frame for coding visual information about objects approaching the hand during motor preparation. Subjects performed a simple visuomanual task while a task-irrelevant distractor ball rapidly approached a location either near to or far from their hand. After the distractor ball appearance, single pulses of transcranial magnetic stimulation were delivered over the subject's primary motor cortex, eliciting motor evoked potentials (MEPs) in their responding hand. MEP amplitude was reduced when the ball approached near the responding hand, both when the hand was on the left and the right of the midline. Strikingly, this suppression occurred very early, at 70-80ms after ball appearance, and was not modified by visual fixation location. Furthermore, it was selective for approaching balls, since static visual distractors did not modulate MEP amplitude. Together with additional behavioral measurements, we provide converging evidence for automatic hand-centered coding of visual space in the human brain.

Host niches and defensive extended phenotypes structure parasitoid wasp communities

Oak galls are spectacular extended phenotypes of gallwasp genes in host oak tissues and have evolved complex morphologies that serve, in part, to exclude parasitoid natural enemies. Parasitoids and their insect herbivore hosts have coevolved to produce diverse communities comprising about a third of all animal species. The factors structuring these communities, however, remain poorly understood. An emerging theme in community ecology is the need to consider the effects of host traits, shaped by both natural selection and phylogenetic history, on associated communities of natural enemies. Here we examine the impact of host traits and phylogenetic relatedness on 48 ecologically closed and species-rich communities of parasitoids attacking gall-inducing wasps on oaks. Gallwasps induce the development of spectacular and structurally complex galls whose species- and generation-specific morphologies are the extended phenotypes of gallwasp genes. All the associated natural enemies attack their concealed hosts through gall tissues, and several structural gall traits have been shown to enhance defence against parasitoid attack. Here we explore the significance of these and other host traits in predicting variation in parasitoid community structure across gallwasp species. In particular, we test the "Enemy Hypothesis,'' which predicts that galls with similar morphology will exclude similar sets of parasitoids and therefore have similar parasitoid communities. Having controlled for phylogenetic patterning in host traits and communities, we found significant correlations between parasitoid community structure and several gall structural traits (toughness, hairiness, stickiness), supporting the Enemy Hypothesis. Parasitoid community structure was also consistently predicted by components of the hosts' spatiotemporal niche, particularly host oak taxonomy and gall location (e.g., leaf versus bud versus seed). The combined explanatory power of structural and spatiotemporal traits on community structure can be high, reaching 62% in one analysis. The observed patterns derive mainly from partial niche specialisation of highly generalist parasitoids with broad host ranges (>20 hosts), rather than strict separation of enemies with narrower host ranges, and so may contribute to maintenance of the richness of generalist parasitoids in gallwasp communities. Though evolutionary escape from parasitoids might most effectively be achieved via changes in host oak taxon, extreme conservatism in this trait for gallwasps suggests that selection is more likely to have acted on gall morphology and location. Any escape from parasitoids associated with evolutionary shifts in these traits has probably only been transient, however, due to subsequent recruitment of parasitoid species already attacking other host galls with similar trait combinations.

Is speeding a "real" antisocial behavior? A comparison with other antisocial behaviors

The relationship between speed and crashes has been well established in the literature, with the consequence that speed reduction through enforced or other means should lead to a reduction in crashes. The extent to which the public regard speeding as a problem that requires enforcement is less clear. Analysis was conducted on public perceptions of antisocial behaviors including speeding traffic. The data was collected as part of the British Crime Survey, a face-to-face interview with UK residents on issues relating to crime. The antisocial behavior section required participants to state the degree to which they perceived 16 antisocial behaviors to be a problem in their area. Results revealed that speeding traffic was perceived as the greatest problem in local communities, regardless of whether respondents were male or female, young, middle aged, or old. The rating of speeding traffic as the greatest problem in the community was replicated in a second, smaller postal survey, where respondents also provided strong support for enforcement on residential roads, and indicated that traveling immediately above the speed limit on residential roads was unacceptable. Results are discussed in relation to practical implications for speed enforcement, and the prioritization of limited police resources. (c) 2006 Elsevier Ltd. All rights reserved.

High leverage interventions: three cases of defensive action and their lessons for OR/MS today.

This paper has two aims. First, to present cases in which scientists developed a defensive system for their homeland: Blackett and the air defense of Britain in WWII, Forrester and the SAGE system for North America in the Cold War, and Archimedes’ work defending Syracuse during the Second Punic War. In each case the historical context and the individual’s other achievements are outlined, and a description of the contribution’s relationship to OR/MS is given. The second aim is to consider some of the features the cases share and examine them in terms of contemporary OR/MS methodology. Particular reference is made to a recent analysis of the field’s strengths and weaknesses. This allows both a critical appraisal of the field and a set of potential responses for strengthening it. Although a mixed set of lessons arise, the overall conclusion is that the cases are examples to build on and that OR/MS retains the ability to do high stakes work.

Imbalanced functional link between executive control network and reward network explain the online-game seeking behaviors in Internet gaming disorder

Literatures have shown that Internet gaming disorder (IGD) subjects show impaired executive control and enhanced reward sensitivities than healthy controls. However, how these two networks jointly affect the valuation process and drive IGD subjects' online-game-seeking behaviors remains unknown. Thirty-five IGD and 36 healthy controls underwent a resting-states scan in the MRI scanner. Functional connectivity (FC) was examined within control and reward network seeds regions, respectively. Nucleus accumbens (NAcc) was selected as the node to find the interactions between these two networks. IGD subjects show decreased FC in the executive control network and increased FC in the reward network when comparing with the healthy controls. When examining the correlations between the NAcc and the executive control/reward networks, the link between the NAcc - executive control network is negatively related with the link between NAcc - reward network. The changes (decrease/increase) in IGD subjects' brain synchrony in control/reward networks suggest the inefficient/overly processing within neural circuitry underlying these processes. The inverse proportion between control network and reward network in IGD suggest that impairments in executive control lead to inefficient inhibition of enhanced cravings to excessive online game playing. This might shed light on the mechanistic understanding of IGD.

Do online hotel rating schemes influence booking behaviors?

Travelers’ hotel booking behaviors increasingly depend on peers' opinions and online ratings. This study investigates the effects of online hotel ratings on travelers' attitudes toward the hotel and booking intentions, using a 2 × 2 experimental research design. The results suggest that online rating lists are more useful and credible when published by well-known online travel communities (e.g., TripAdvisor). More favorable attitudes toward a hotel and higher booking intentions emerge when the hotel appears in best hotels lists. Finally, for the entries on best hotels lists, better attitudes and higher booking intentions result if the list is published on a well-known online travel community (Tripadvisor), whereas for entries on a worst hotel list, attitudes and booking intentions decrease even further if the list appears on TripAdvisor.

Stigma and risky behaviors among male clients of sex workers in the UK in 2001

This paper builds on existing theoretical work on sex markets (Della Giusta, Di Tommaso, and Strøm, 2009a). Using data from the British Sexual Attitudes Survey, we aim to replicate the analysis of the demand for paid sex previously conducted for the US (Della Giusta, Di Tommaso, Shima and Strøm, 2009b). We want to test formally the effect of attitudes, risky behaviors and personal characteristics on the demand for paid sex. Findings from empirical studies of clients suggest that personal characteristics (personal and family background, self-perception, perceptions of women, sexual preferences etc), economic factors (education, income, work) as well as attitudes towards risk (both health hazard and risk of being caught where sex work is illegal), and attitude towards relationships and sex are all likely to affect demand. Previous theoretical work has argued that stigma plays a fundamental role in determining both demand and risk, and that in particular due to the presence of stigma the demand for sex and for paid sex are not, as has been argued elsewhere, perfect substitutes. We use data from the British Sexual Attitudes Survey of 2001 to test these hypotheses. We find a positive effect of education (proxy for income), negative effects of professional status (proxies for stigma associated with buying sex), positive and significant effects of all risky behavior variables and no significant effects of variables which measure the relative degree of conservatism in morals. We conclude with some policy implications.