The structure of borders in a small world

Geographic borders are not only essential for the effective functioning of government, the distribution of administrative responsibilities and the allocation of public resources, they also influence the interregional flow of information, cross-border trade operations, the diffusion of innovation and technology, and the spatial spread of infectious diseases. However, as growing interactions and mobility across long distances, cultural, and political borders continue to amplify the small world effect and effectively decrease the relative importance of local interactions, it is difficult to assess the location and structure of effective borders that may play the most significant role in mobility-driven processes. The paradigm of spatially coherent communities may no longer be a plausible one, and it is unclear what structures emerge from the interplay of interactions and activities across spatial scales. Here we analyse a multi-scale proxy network for human mobility that incorporates travel across a few to a few thousand kilometres. We determine an effective system of geographically continuous borders implicitly encoded in multi-scale mobility patterns. We find that effective large scale boundaries define spatially coherent subdivisions and only partially coincide with administrative borders. We find that spatial coherence is partially lost if only long range traffic is taken into account and show that prevalent models for multi-scale mobility networks cannot account for the observed patterns. These results will allow for new types of quantitative, comparative analyses of multi-scale interaction networks in general and may provide insight into a multitude of spatiotemporal phenomena generated by human activity.Comment: 9 page

Antibiotics in acute bronchitis: a meta-analysis.

PurposeMost patients with acute bronchitis who seek medical care are treated with antibiotics, although the effectiveness of this intervention is uncertain. We performed a meta-analysis of randomized, controlled trials to estimate the effectiveness of antibiotics in the treatment of acute bronchitis.Subjects and methodsEnglish-language studies published January 1966 to April 1998 were retrieved using MEDLINE, bibliographies, and consultation with experts. Only randomized trials that enrolled otherwise healthy patients with a diagnosis of acute bronchitis, used an antibiotic in the treatment group and a placebo in the control group, and provided sufficient data to calculate an effect size were included.ResultsWe identified eight randomized controlled trials that satisfied all inclusion criteria. These studies used one of three antibiotics (erythromycin, doxycycline, trimethoprim/sulfamethoxazole). The use of antibiotics decreased the duration of cough and sputum production by approximately one-half day (summary effect size 0.21; 95% CI, 0.05 to 0.36). For specific symptoms, there were nonsignificant trends favoring the use of antibiotics: a decrease of 0.4 days of purulent sputum (95% CI, -0.1 to 0.8), a decrease of 0.5 days of cough (95% CI, -0.1 to 1.1), and a decrease of 0.3 days lost from work (95% CI, -0.6 to 1.1).ConclusionThis meta-analysis suggests a small benefit from the use of the antibiotics erythromycin, doxycycline, or trimethoprim/sulfamethoxazole in the treatment of acute bronchitis in otherwise healthy patients. As this small benefit must be weighed against the risk of side effects and the societal cost of increasing antibiotic resistance, we believe that the use of antibiotics is not justified in these patients

Design and Craft Education, some fundamental questions: "Lacking an appreciation of the base, a sound grounding in craft skills, they have sought to extend the necessarily ephemeral qualities of design work into the school curriculum"

Having had my attention drawn to the concern felt by craft teachers about recent developments in craft and design work in schools and, as the head of a department in which many of the ideas promoted by the Research and Development Project have been adopted as part of the normal programme of work, I feel able to comment on some aspects of Design and Craft Education that seem to need attention. It will be a tragedy if the main core of the work conducted by the Research and Development Project team becomes neglected because some of the ideas suggested provide convenient and vulnerable targes for criticism.Perhaps the largest single area of concern is the emphasis on Design as an activity rather than Craft. (The cover of Vol 5 No.1 of Studies in Design Education and Craft with its stress on design education and the almost total exclusion of the word craft is indicative of an attitude that is worrying). Let me first admit, there are many partly formed ideas of what is meant by 'Design Education' in circulation. Some of these are quite erroneous and their holders are not confined to the teaching profession. I think it is now widely accepted that what has passed for craft education in the past did not attain the ideal at which it was aimed. (This is not a case for declaring that ideal invalid.) All too many pupils suffered a stifling experience. On the other hand, many pupils found fulfilment and great enjoyment but, very little has been mentioned of their experiences. (I am firmly convinced a large proportion of the ";do it yourself' movement has its basic roots in successful school craft activities on the part of many past pupils.) The main worry, therefore, is that too much emphasis has been, and is being, placed on Design. Craft, particularly craftsmanship, is in the process of being relegated to a secondary or, supporting role. The extension of this, of course, is that a construction on Design can easily be diverted into a predominately 'Art' approach. (The article ";Metropolis";, op.cit. illustrates this. I find the whole experiment, as described, an operation singularly devoid of attributes assoCiated with craft and craftsmanship. Most of the work carried out was of a transient nature. This approaches the ideas underlying much of what is called 'Art' today.) The number of College of Education craft courses absorbed into Art and Design departments is increasing and indicative of the trend. I have also heard arguments subjugating craftsmanship amongst the advocates of Technology and Craft ideas, particularly in some Project Technology regional circles. To me, it is increasingly significant that words expressing vague meanings like 'Technology' and 'Design' are replacing words having definite meanings. This is confirmation of a growing lack of certainty in educational thinking

Spectroscopy of Stardust from 200nm to 16µM (with a gap in the middle)

UV/Vis and IR spectroscopy are complementary, non-destructive techniques that can be used to identify the presence of a range of organic and inorganic, hydrated and anhydrous minerals within micron-sized grains. We look forward to applying these techniques to the Stardust materials

Mechanisms of fragmentation of Al-W granular composites under dynamic loading

Numerical simulations of Aluminum (Al) and Tungsten (W) granular composite rings under various dynamic loading conditions caused by explosive loading were examined. Three competing mechanisms of fragmentation were observed: a continuum level mechanism generating large macrocracks described by the Grady-Kipp fragmentation mechanism, a mesoscale mechanism generating voids and microcracks near the initially unbonded Al/W interfaces due to tensile strains, and a mesoscale jetting due to the development of large velocity gradients between the W particles and adjacent Al. These mesoscale mechanisms can be used to tailor the size of the fragments by selecting an appropriate initial mesostructure for a given loading condition.Comment: 10 pages, 3 figures, submitted to AP

Group conflict and intergroup contact

This dissertation contains three papers. The first paper studies the effects of a peacebuilding intervention randomly assigned to conflicting farming and pastoral communities in Nigeria, where thousands die each year in farmer-pastoralist violence. Members of conflicting farming and pastoral groups worked together to build infrastructure projects beneficial to both communities, and that collaboration increased voluntary intergroup contact, intergroup trust, and feelings of security for the participants and for nonparticipants living in the same villages as the participants. The second paper uses a lab experiment to test a specific mechanism through which contact might work. Subjects vicariously experienced intergroup contact that either achieved or failed to achieve a joint goal. It finds that contact only improves attitudes towards the outgroup when it achieves a goal and that contact only improves attitudes of the majority group towards the minority group, not of the minority towards the majority group. The third paper bridges perspectives on group conflict in political economy and political psychology. The political economy literature focuses on bargaining; the political psychology literature focuses on group identities. This paper demonstrates that these two perspectives can work together by applying the group identity perspective to the bargaining perspective, showing how group identities and related psychological and cognitive biases complicate bargaining

Sufficient Conditions for an Operator-Valued Feynman-Kac Formula

Let E be a locally compact, second countable Hausdorff space and let X(t) be a Markov process with state space E. Sufficient conditions are given for the existence of a solution to the initial value problem, ∂u/∂t,=Au + V(x) * u, u(0) = f, where A is the infinitesimal generator of the process X on a certain Banach space and for each x ∈ E, V(x) is the infinitesimal generator of a C0 contraction semigroup on another Banach space

Ancient Cosmic Dust from Triassic Halite

We describe the discovery of fossil micrometeorites in ancient Triassic rock salt; the first to be found in salt and the oldest complete micrometeorites found to date. We present an estimated flux rate of micrometeorites to Earth at this time