Global regularity of three-dimensional Ricci limit spaces

In their recent work [ST17], Miles Simon and the second author established a local bi-Hölder correspondence between weakly noncollapsed Ricci limit spaces in three dimensions and smooth manifolds. In particular, any open ball of finite radius in such a limit space must be bi-Hölder homeomorphic to some open subset of a complete smooth Riemannian three-manifold. In this work we build on the technology from [ST16, ST17] to improve this local correspondence to a global-local correspondence. That is, we construct a smooth three-manifold M, and prove that the entire (weakly) noncollapsed three-dimensional Ricci limit space is homeomorphic to M via a globally-defined homeomorphism that is bi-Hölder once restricted to any compact subset. Here the bi-Hölder regularity is with respect to the distance dg on M, where g is any smooth complete metric on M. A key step in our proof is the construction of local pyramid Ricci flows, existing on uniform regions of spacetime, that are inspired by Hochard’s partial Ricci flows [Hoc16]. Suppose (M, g0, x0) is a complete smooth pointed Riemannian three-manifold that is (weakly) noncollapsed and satisfies a lower Ricci bound. Then, given any k ∈ N, we construct a smooth Ricci flow g(t) living on a subset of spacetime that contains, for each j ∈ {1, . . . , k}, a cylinder Bg0 (x0, j) × [0, Tj ], where Tj is dependent only on the Ricci lower bound, the (weakly) noncollapsed volume lower bound and the radius j (in particular independent of k) and with the property that g(0) = g0 throughout Bg0 (x0, k).</p

How soccer players head the ball: a test of optic acceleration cancellation theory with virtual reality

We measured the movements of soccer players heading a football in a fully immersive virtual reality environment. In mid-flight the ball’s trajectory was altered from its normal quasi-parabolic path to a linear one, producing a jump in the rate of change of the angle of elevation of gaze (α) from player to ball. One reaction time later the players adjusted their speed so that the rate of change of α increased when it had been reduced and reduced it when it had been increased. Since the result of the player’s movement was to regain a value of the rate of change close to that before the disturbance, the data suggest that the players have an expectation of, and memory for, the pattern that the rate of change of α will follow during the flight. The results support the general claim that players intercepting balls use servo control strategies and are consistent with the particular claim of Optic Acceleration Cancellation theory that the servo strategy is to allow α to increase at a steadily decreasing rate

Farmer evaluation of biocontrol methods against rootknot nematodes in tomatoes

This report was presented at the UK Organic Research 2002 Conference. Root-knot nematodes in tomatoes cause financial loss to Kenyan smallholders. While soil fumigation appears to be losing effectiveness two bio-control agents (bcas), Pasteuria penetrans and Verticillium chlamydosporium, appear promising. Participatory budgeting is being used to compare the bcas with chemical and other biological controls on commercial and organic smallholdings

Non-Infringing Uses in Digital Sampling: The Role of Fair Use and the de Minimis Threshold in Sample Clearance Reform

In this book excerpt, the authors address the role of two major legal exceptions to copyright protection in the music industry’s practices surrounding digital sampling. Although the United States law on the books requires a balance between the interests of copyright owners and sampling musicians, the business practice has been to mandate licensing in almost every instance. Despite this hurdle to a more balanced approach to sampling, the authors discuss several benefits that might come through doctrinal or statutory reforms, or even through developing best practices for claiming fair use

Can the Use of Web 2.0 Tools Help Deliver 21st Century Learning?

It has long been recognized that people need to be literate to function optimally within society. The 21st century has seen technology increase the complexity of environments, so that a literate person must now possess a wide range of abilities, competencies, and literacies. These have often been referred to as “21st-century skills” and while many of them are not new, the extent to which individual success depends on having such skills is new. The current study seeks to explore ways in which technology can be used to increase literacy and enhance 21st century skills in students. 1193 students attending Sahmyook University in Seoul, South Korea were placed in small groups and asked to make a movie in English. This constructivist, real-world, group-based project required students to collaboratively negotiated their way through a variety of language, technical and social challenges using a wiki. We can conclude from this study that collaborative projects, supported by web 2.0 tools, can deliver worthwhile learning. Students reported that the project; was interesting and rewarding, improved their relationships with classmates, encouraged teamwork, improved English skills, facilitated positive attitudes and the development of ICT skills. Students experienced improved technical, collaborative, leadership, critical thinking and problem solving skills that enhanced knowledge and contributed to their personal 21st century skill set

Institutionalization as a contributing factor in antisocial behaviour : implications for statutory social work practice

Bibliography: pages 211-235.This study looks at the role of statutory social work practice within the framework of current South African legislation. The implications of this legislation for persons exhibiting antisocial behaviour were examined in the light of institutional and community-based management options. An overview of the literature is presented in order to place the concepts of institutional care, community-based options and legal reform in perspective. These literature studies provided the framework for an exploratory survey of 70 purposely sampled statutory social work clients, with a view to re-examining institutionalization as a possible contributing factor in their antisocial behaviour. Using a structured interview schedule, the Researcher elicited information concerning the respondents' histories of institutionalization, their evaluations of its effects and other possible factors contributing to their antisocial behaviour. The outcome of the study confirmed the major research question, namely that institutionalization could be regarded as a contributing factor in antisocial behaviour. Conversely, the findings reflected major literature surveys which stated that institutionalization has an adaptive potential for certain client systems. Results flowing from both negative and positive factors are mediated by the characteristics of the institution; by those who are institutionalized, and by other factors which precede, coexist with or follow institutionalization. The study supports the preferential use of community-based alternatives in statutory social work as well as providing guidelines for institutional reform and future research

Identifying which septic patients have increased mortality risk using severity scores:a cohort study

Background: Early aggressive therapy can reduce the mortality associated with severe sepsis but this relies on prompt recognition, which is hindered by variation among published severity criteria. Our aim was to test the performance of different severity scores in predicting mortality among a cohort of hospital inpatients with sepsis. Methods: We anonymously linked routine outcome data to a cohort of prospectively identified adult hospital inpatients with sepsis, and used logistic regression to identify associations between mortality and demographic variables, clinical factors including blood culture results, and six sets of severity criteria. We calculated performance characteristics, including area under receiver operating characteristic curves (AUROC), of each set of severity criteria in predicting mortality. Results: Overall mortality was 19.4% (124/640) at 30 days after sepsis onset. In adjusted analysis, older age (odds ratio 5.79 (95% CI 2.87-11.70) for &ge;80y versus &lt;60y), having been admitted as an emergency (OR 3.91 (1.31-11.70) versus electively), and longer inpatient stay prior to sepsis onset (OR 2.90 (1.41-5.94) for &gt;21d versus &lt;4d), were associated with increased 30 day mortality. Being in a surgical or orthopaedic, versus medical, ward was associated with lower mortality (OR 0.47 (0.27-0.81) and 0.26 (0.11-0.63), respectively). Blood culture results (positive vs. negative) were not significantly association with mortality. All severity scores predicted mortality but performance varied. The CURB65 community-acquired pneumonia severity score had the best performance characteristics (sensitivity 81%, specificity 52%, positive predictive value 29%, negative predictive value 92%, for 30 day mortality), including having the largest AUROC curve (0.72, 95% CI 0.67-0.77). Conclusions: The CURB65 pneumonia severity score outperformed five other severity scores in predicting risk of death among a cohort of hospital inpatients with sepsis. The utility of the CURB65 score for risk-stratifying patients with sepsis in clinical practice will depend on replicating these findings in a validation cohort including patients with sepsis on admission to hospital