Vibrating soap films: An analog for quantum chaos on billiards

We present an experimental setup based on the normal modes of vibrating soap films which shows quantum features of integrable and chaotic billiards. In particular, we obtain the so-called scars -narrow linear regions with high probability along classical periodic orbits- for the classically chaotic billiards. We show that these scars are also visible at low frequencies. Finally, we suggest some applications of our experimental setup in other related two-dimensional wave phenomena.Comment: 5 pages, 7 figures. Better Postscript figures available on reques

Vacancies, twins, and the thermal stability of ultrafine-grained copper

Ultrafine-grained metals have impressive strength but lack the thermal stability necessary for most applications. Nano-scale, deformation twinned copper microstructures exhibit a rare combination of strength and stability. While storing less energy in their interfaces than other nanostructured metals, they also exhibit lower vacancy supersaturations, reducing the driving force and mobility for microstructure evolution. From a thermal stability perspective, the nano-twinned microstructure may thus be preferred over the more commonly produced nano-scale equiaxed microstructures

Patient safety in dentistry: development of a candidate 'never event' list for primary care

Introduction The 'never event' concept is often used in secondary care and refers to an agreed list of patient safety incidents that 'should not happen if the necessary preventative measures are in place'. Such an intervention may raise awareness of patient safety issues and inform team learning and system improvements in primary care dentistry. Objective To identify and develop a candidate never event list for primary care dentistry. Methods A literature review, eight workshops with dental practitioners and a modified Delphi with 'expert' groups were used to identify and agree candidate never events. Results Two-hundred and fifty dental practitioners suggested 507 never events, reduced to 27 distinct possibilities grouped across seven themes. Most frequently occurring themes were: 'checking medical history and prescribing' (119, 23.5%) and 'infection control and decontamination' (71, 14%). 'Experts' endorsed nine candidate never event statements with one graded as 'extreme risk' (failure to check past medical history) and four as 'high risk' (for example, extracting wrong tooth). Conclusion Consensus on a preliminary list of never events was developed. This is the first known attempt to develop this approach and an important step in determining its value to patient safety. Further work is necessary to develop the utility of this method

Consequences of swamp forest fragmentation on assemblages of vascular epiphytes and climbing plants: Evaluation of the metacommunity structure

Aim Habitat reduction in fragmented landscapes provides an opportunity to study the biogeographic patterns that drive changes in diversity in poorly studied metacommunities. In this study, colonization-extinction dynamics were indirectly evaluated through the analysis of the species-area relationship and the nestedness of vascular epiphytes and climbing plants in 30 swamp forest fragments. Location Coast of the Araucania Region in Chile. Taxon Vascular epiphytes (16 species, mainly Pteridophytes) and climbing plants (15 species). Methods We used the database in Pincheira-Ulbrich et al. (New Zealand Journal of Botany, 54, 2016, 458), where 904 trees were sampled and a total abundance of 41,097 fern fronds and 3,098 climbing stems were reported. For the species-area relationship, a simple linear regression model (SLR) and two models that consider the spatial autocorrelation of species richness among fragments, generalized least squares (GLS) and simultaneous autoregressive model (SAR), were compared. For the species nestedness, the nestedness measure based on overlap and decreasing fills (NODF) and weighted nestedness metric based on overlap and decreasing fill (WNODF) indexes were used on presence-absence and abundance matrices, respectively. These matrices were sorted by area size and distance from the largest fragment and then contrasted with the probability distribution of a randomized null model based on 10,000 simulations. Results The results showed that the area size had a significantly positive effect on epiphyte species richness, while spatial autocorrelation played a fundamental role in explaining the richness of climbing plants. Both metacommunities had a general nestedness structure in terms of species incidence, which was determined first by area size and secondly by isolation. Main conclusions Our results indicate that local colonization processes determined by species' dispersal capacities could be the predominant mechanism for the spatial configuration of climbing plant species composition. On the other hand, selective extinction determined by patch size could characterize the spatial structure of epiphyte species' compositio

From the abstract to the concrete - Implementation of an innovative tool in home care

Background: The implementation of innovations in practice is a critical factor for change and development processes in health and home care. We therefore analyze how an innovative tool - a mobility agreement to maintain physical mobility of home care clients - was implemented in Finnish home care. Methods: Our study involves ethnographic research of 13 home care visits, two years after the mobility agreement was implemented. We analyze the emergence of contradictions, the motives of the actors and the use of artifacts supporting or inhibiting the implementation. Two in-depth cases illustrate the implementation of the mobility agreement in home care visits. Findings: Our findings show that, first, to achieve practice change and development, the innovation implementation requires the overcoming of contradictions in the implementation process. Second, it calls for the emergence of a shared motive between the actors to transform the abstract concept of an innovation into a concrete practice. Third, artifacts, customary to the clients are important in supporting the implementation process. Fourth, the implementation brings about a modification of the innovation and the adopting social system. Conclusions: Innovation implementation should be seen as a transformation process of an abstract concept into a concrete practice, enabled by the actors involved. Concept design and implementation should be closely linked. In health/home care innovation management, the implementation of innovations needs to be understood as a complex collective learning process. Results can be far reaching - in our case leading to change of home care workers' professional understanding and elderly clients' mobility habits.Peer reviewe

Alternative networks: toward global access to the Internet for all

It is often said that the Internet is ubiquitous in our daily lives, but this holds true only for those who can easily access it. In fact, billions of people are still digitally disconnected, as bringing connectivity to certain zones does not make a good business case. The only solution for these unsatisfied potential users is to directly undertake the building of the infrastructure required to obtaining access to the Internet, typically forming groups in order to share the corresponding cost. This article presents a global classification and a summary of the main characteristics of different Alternative Network deployments that have arisen in recent years with an aim to provide Internet services in places where mainstream network deployments do not exist or are not adequate solutions. The Global Access to the Internet for All Research Group of the Internet Research Task Force, where all authors actively participate, is interested in documenting these emerging deployments. As an outcome of this work, a classification has converged by consensus, where five criteria have been identified and, based on them, four different types of Alternative Networks have been identified and described with real-world examples. Such a classification is useful for a deeper understanding of the common characteristics behind existing and emerging Alternative Networks

Burnout and Mental Health Stigma among Juvenile Probation Officers: The Moderating Effect of Participatory Atmosphere

Despite high rates of mental health problems among juvenile justice-involved youth, mental health stigma among juvenile probation officers (JPOs) is under-studied. This cross-sectional study examined effects of job burnout and workplace participatory atmosphere on mental health stigma among JPOs across Indiana (n = 226). Participatory atmosphere moderated the relationship between JPO burnout-related cynicism and mental health stigma (interaction β = - 0.14, p = .04); burnout was related to greater mental health stigma at low levels of participatory atmosphere. Findings suggest participatory atmosphere mitigates effects of burnout on mental health stigma among JPOs. Organizational-level interventions might help to reduce mental health stigma and combat negative effects from burnout among JPOs

ON PROCESS STABILITY IN WAAM-CMT OF ALUMINUM ALLOYS

Wire-arc additive manufacturing (WAAM) has become a cost-efficient metal additive manufacturing process. However, depositing aluminum with WAAM is challenging due to its sensitivity to heat input (linear energy density), which can cause undesirable surface topology waviness if not controlled. Thus, a process window is needed that can produce stable geometry and deposition conditions while minimizing production times. In this study, 5183 aluminum alloy wire is used to deposit 10-layer walls with varying wire feed speeds (WFS) and traverse speeds (TS) (at a constant WFS/TS ratio) and varying interpass temperature (IPT). In-situ process data consisting of optical contact-tip-workpiece-distance (CTWD) and current/voltage measurements are collected to determine process condition stability throughout the build. Part geometry is measured using a 3D scanner and build porosity is characterized via digital X-ray. A process window is identified that produces stable surface topology and process conditions at a minimal production time.Mechanical Engineerin