It is suggested that the world is locally projectively flat rather than Euclidean. From this postulate it is shown that an (N+1)-particle system has the global geometry of the symmetric spaceSO(4,N+1)/SO(4)×SO(N+1). A complex representation also exists, with structureSU(2,N+1)/S[U(2)×U(N+1)]. Several aspects of these geometrics are developed. Physical states are taken to be eigenfunctions of the Laplace-Beltrami operators. The theory may provide a rational basis for comprehending the groupsSO(4, 2),SU(2)×U(1),SU(3), etc., of current interest.

A thorough account of Africa's history and its lasting influence on Western culture told from the perspective of the disparate descendants who inherited its legacy. W.E.B. Du Bois highlights the hidden stories that connect these varied communities. Originally published in 1915, The Negro presents an expansive analysis of the African diaspora over the course of history. W.E.B. Du Bois uses a critical eye to survey the early depictions of the continent, debunking stereotypical myths about its social structure. He addresses the (...) generational impact of slavery as well as the capitalistic system that made it possible. It's an honest look at the effects of white supremacy, classism and its place in modern society. From Ethiopia and Egypt to the West Indies and Latin America, Africa's influence is undeniable. The Negro sheds light on the ignored history of the continent and its many descendants. It's a vital piece of literature that acknowledges and celebrates its cultural power. With an eye-catching new cover, and professionally typeset manuscript, this edition of The Negro is both modern and readable. (shrink)

Autism spectrum disorders (ASD) are thought to result in part from altered cortical excitatory-inhibitory balance; this pathophysiology may impact the generation of oscillations on EEG. We investigated premotor-parietal cortical physiology associated with praxis, which has strong theoretical and empirical associations with ASD symptomatology. 25 children with high-functioning ASD (HFA) and 33 controls performed a praxis task involving the pantomiming of tool use, while EEG was recorded. We assessed task-related modulation of signal power in alpha and beta frequency bands. Compared with (...) controls, subjects with HFA showed 27% less left central (motor/premotor) beta (18-22 Hz) event-related desynchronization (ERD) (p = 0.030), as well as 24% less left parietal alpha (7-13 Hz) ERD (p = 0.046). Within the HFA group, blunting of central ERD attenuation was associated with impairments in clinical measures of praxis imitation (r = -0.4; p = 0.04) and increased autism severity (r = 0.48; p = 0.016). The modulation of central beta activity is associated, among other things, with motor imagery, which may be necessary for imitation. Impaired imitation has been associated with core features of ASD. Altered modulation of oscillatory activity may be mechanistically involved in those aspects of motor network function that relate to the core symptoms of ASD. (shrink)

Our primary goal was to develop and validate a task that could provide evidence about how humans learn praxis gestures, such as those involving the use of tools. To that end, we created a video-based task in which subjects view a model performing novel, meaningless one-handed actions with kinematics similar to praxis gestures. Subjects then imitated the movements with their right hand. Trials were repeated 6 times to examine practice effects. EEG was recorded during the task. As a control, subjects (...) watched videos of a model performing a well-established (over learned) tool-use gesture. These gestures were also imitated 6 times. Demonstrating convergent validity, EEG measures of task-related cortical activation were similar in topography and frequency between the novel gesture task and the overlearned, praxis gesture task. As in studies assessing motor skill learning with simpler tasks, cortical activation during novel gesture learning decreased as the same gestures were repeated. In the control condition, repetition of overlearned tool-use gestures were also associated with reductions in activation, though to a lesser degree. Given that even overlearned, praxis gestures show constriction of EEG activity with repetition, it is possible that that attentional effects drive some of the repetition effects seen in EEG measures of activation during novel gesture repetition. (shrink)

The operational definition of a weak value for a quantum mechanical system involves the limit of the weak measurement strength tending to zero. I study how this limit compares to the situation for the undisturbed system. Under certain conditions, which I investigate, this limit is discontinuous in the sense that it does not merge smoothly to the Hilbert space description of the undisturbed system. Hence, in these discontinuous cases, the weak value does not represent the undisturbed system. As a result, (...) conclusions drawn from such weak values regarding the properties of the studied system cannot be upheld. Examples are given. (shrink)

The necessity of incorporating societal and environmental concerns into publicly funded agricultural initiatives in research, extension, and practice is increasingly evident. Agriculturalists are urged to acknowledge and respond to societal concerns before an insensitive and largely ill-informed urban majority assumes a dominant posture in agricultural policy. In recent history, the availability of unrealistically cheap energy encouraged the evolution of a form of commercial agriculture unfettered by sound ecological principles. At present, external, resource-intensive intervention of increasing magnitude is needed to compensate (...) for the apparent ecological instability generated by practices such as intensive cereal management or conservation tillage practices. Polarization of the enterprises of plant and animal agriculture to enable centralized, concentrate-intensive, confinement feeding has disrupted the natural cycling of nutrients and carbon in the soil, encouraged the withdrawal of perennial forages from crop rotations, and invoked a widely ramifying network of agricultural and societal problems. Solutions to these problems must evolve from a holistic and far-reaching appraisal of causes, rather than from a piecemeal approach to individual symptoms. (shrink)

Background: The factors influencing parents’ willingness to enroll their children in biobanks are poorly understood. This study sought to assess parents’ willingness to enroll their children, and their perceived benefits, concerns, and information needs under different consent and data-sharing scenarios, and to identify factors associated with willingness. Methods: This large, experimental survey of patients at the 11 eMERGE Network sites used a disproportionate stratified sampling scheme to enrich the sample with historically underrepresented groups. Participants were randomized to receive one of (...) three consent and data-sharing scenarios. Results: In total, 90,000 surveys were mailed and 13,000 individuals responded (15.8% response rate). 5737 respondents were parents of minor children. Overall, 55% (95% confidence interval 50–59%) of parents were willing to enroll their youngest minor child in a hypothetical biobank; willingness did not differ between consent and data-sharing scenarios. Lower educational attainment, higher religiosity, lower trust, worries about privacy, and attitudes about benefits, concerns, and information needs were independently associated with less willingness to allow their child to participate. Of parents who were willing to participate themselves, 25% were not willing to allow their child to participate. Being willing to participate but not willing to allow one’s child to participate was independently associated with multiple factors, including race, lower educational attainment, lower annual household income, public health care insurance, and higher religiosity. Conclusions: Fifty-five percent of parents were willing to allow their youngest minor child to participate in a hypothetical biobank. Building trust, protecting privacy, and addressing attitudes may increase enrollment and diversity in pediatric biobanks. (shrink)

People who expect to be successful in regulating their emotions tend to experience less frequent negative emotions and are less likely to suffer from depression. It is not clear, however, whether beliefs about the likelihood of success in emotion regulation can shape actual emotion regulation success. To test this possibility, we manipulated participants' beliefs about the likelihood of success in emotion regulation and assessed their subsequent ability to regulate their emotions during a negative emotion induction. We found that participants who (...) were led to expect emotion regulation to be more successful were subsequently more successful in regulating their emotional responses, compared to participants in the control condition. Our findings demonstrate that expected success can contribute to actual success in emotion regulation. (shrink)

The unbridled positivity toward curiosity and creativity may be excessive. Both aid species survival through exploration and advancement. These beneficial effects are well documented. What remains is to understand their optimal levels and contexts for maximal achievement, health, and well-being. Every beneficial element to individuals and groups carries the potential for harm – curiosity and creativity included.

The Fragments of Pindar have not, so far as I know, been adequately discussed since the great editions of Boeckh and Dissen, and as many of them are extremely important, the following remarks are offered in the hope of turning the attention of scholars in their direction.