Universal shapes formed by two interacting cracks

We investigate the origins of the widely-observed "en passant" crack pattern which forms through interactions between two approaching cracks. A rectangular elastic plate is notched on each long side and then subjected to quasistatic uniaxial strain from the short side. The two cracks propagate along approximately straight paths until they pass each other, after which they curve and release a lenticular fragment. We find that for materials with diverse mechanical properties, the shape of this fragment has an aspect ratio of 2:1, with the length scale set by the initial crack offset $s$ and the time scale set by the ratio of $s$ to the pulling velocity. The cracks have a universal square root shape which we understand using a simple geometric model of the crack-crack interaction

Selling a service: experiences of peer supporters while promoting exclusive infant feeding in three sites in South Africa

<p>Abstract</p> <p>Background</p> <p>Even though it has been shown that peer support to mothers at home helps to increase exclusive breastfeeding, little is known about the experiences of peer supporters themselves and what is required of them to fulfil their day-to-day tasks. Therefore, a community-based randomised control trial using trained "lay" women to support exclusive infant feeding at home was implemented in three different sites across South Africa. The aim of this paper is to describe the experiences of peer supporters who promote exclusive infant feeding.</p> <p>Methods</p> <p>Three focus group discussions were held, in a language of their choice, with peer supporters. These meetings focused on how the peer educators utilised their time in the process of delivering the intervention. Data from the discussions were transcribed, with both verbatim and translated transcripts being used in the analysis.</p> <p>Results</p> <p>Unlike the services provided by mainstream health care, peer supporters had to market their services. They had to negotiate entry into the mother's home and then her life. Furthermore, they had to demonstrate competence and come across as professional and trustworthy. An HIV-positive mother's fear of being stigmatised posed an added burden - subsequent disclosure of her positive status would lead to an increased workload and emotional distress. Peer supporters spent most of their time in the field and had to learn the skill of self-management. Their support-base was enhanced when supervision focused on their working conditions as well as the delivery of their tasks. Despite this, they faced other insurmountable issues, such as mothers being compelled to offer their infants mixed feeding simultaneously due to normative practices and working in the fields postpartum.</p> <p>Conclusion</p> <p>Designers of peer support interventions should consider the skills required for delivering health messages and the skills required for selling a service. Supportive supervision should be responsive both to the health care task and the challenges faced in the process of delivering it.</p> <p>Trial registration</p> <p>NCT00297150.</p

Defect turbulence in inclined layer convection

We report experimental results on the defect turbulent state of undulation chaos in inclined layer convection of a fluid withPrandtl number $\approx 1$. By measuring defect density and undulation wavenumber, we find that the onset of undulation chaos coincides with the theoretically predicted onset for stable, stationary undulations. At stronger driving, we observe a competition between ordered undulations and undulation chaos, suggesting bistability between a fixed-point attractor and spatiotemporal chaos. In the defect turbulent regime, we measured the defect creation, annihilation, entering, leaving, and rates. We show that entering and leaving rates through boundaries must be considered in order to describe the observed statistics. We derive a universal probability distribution function which agrees with the experimental findings.Comment: 4 pages, 5 figure

Selling a service: experiences of peer supporters while promoting exclusive infant feeding in three sites in South Africa

Background: Even though it has been shown that peer support to mothers at home helps to increase exclusive breastfeeding, little is known about the experiences of peer supporters themselves and what is required of them to fulfil their day-to-day tasks. Therefore, a community-based randomised control trial using trained “lay” women to support exclusive infant feeding at home was implemented in three different sites across South Africa. The aim of this paper is to describe the experiences of peer supporters who promote exclusive infant feeding. Methods: Three focus group discussions were held, in a language of their choice, with peer supporters. These meetings focused on how the peer educators utilised their time in the process of delivering the intervention. Data from the discussions were transcribed, with both verbatim and translated transcripts being used in the analysis. Results: Unlike the services provided by mainstream health care, peer supporters had to market their services. They had to negotiate entry into the mother’s home and then her life. Furthermore, they had to demonstrate competence and come across as professional and trustworthy. An HIV-positive mother’s fear of being stigmatised posed an added burden - subsequent disclosure of her positive status would lead to an increased workload and emotional distress. Peer supporters spent most of their time in the field and had to learn the skill of selfmanagement. Their support-base was enhanced when supervision focused on their working conditions as well as the delivery of their tasks. Despite this, they faced other insurmountable issues, such as mothers being compelled to offer their infants mixed feeding simultaneously due to normative practices and working in the fields postpartum. Conclusion: Designers of peer support interventions should consider the skills required for delivering health messages and the skills required for selling a service. Supportive supervision should be responsive both to the health care task and the challenges faced in the process of delivering it.publishedVersio

The Influence of Network Topology on Sound Propagation in Granular Materials

Granular materials, whose features range from the particle scale to the force-chain scale to the bulk scale, are usually modeled as either particulate or continuum materials. In contrast with either of these approaches, network representations are natural for the simultaneous examination of microscopic, mesoscopic, and macroscopic features. In this paper, we treat granular materials as spatially-embedded networks in which the nodes (particles) are connected by weighted edges obtained from contact forces. We test a variety of network measures for their utility in helping to describe sound propagation in granular networks and find that network diagnostics can be used to probe particle-, curve-, domain-, and system-scale structures in granular media. In particular, diagnostics of meso-scale network structure are reproducible across experiments, are correlated with sound propagation in this medium, and can be used to identify potentially interesting size scales. We also demonstrate that the sensitivity of network diagnostics depends on the phase of sound propagation. In the injection phase, the signal propagates systemically, as indicated by correlations with the network diagnostic of global efficiency. In the scattering phase, however, the signal is better predicted by meso-scale community structure, suggesting that the acoustic signal scatters over local geographic neighborhoods. Collectively, our results demonstrate how the force network of a granular system is imprinted on transmitted waves.Comment: 19 pages, 9 figures, and 3 table

Prevalence and Characteristics of Autism Spectrum Disorder Among Children Aged 4 Years - Early Autism and Developmental Disabilities Monitoring Network, Seven Sites, United States, 2010, 2012, and 2014

Problem/Condition: Autism spectrum disorder (ASD) is estimated to affect up to 3% of children in the United States. Public health surveillance for ASD among children aged 4 years provides information about trends in prevalence, characteristics of children with ASD, and progress made toward decreasing the age of identification of ASD so that evidence-based interventions can begin as early as possible. Period Covered: 2010, 2012, and 2014. Description of System: The Early Autism and Developmental Disabilities Monitoring (Early ADDM) Network is an active surveillance system that provides biennial estimates of the prevalence and characteristics of ASD among children aged 4 years whose parents or guardians lived within designated sites. During surveillance years 2010, 2012, or 2014, data were collected in seven sites: Arizona, Colorado, Missouri, New Jersey, North Carolina, Utah, and Wisconsin. The Early ADDM Network is a subset of the broader ADDM Network (which included 13 total sites over the same period) that has been conducting ASD surveillance among children aged 8 years since 2000. Each Early ADDM site covers a smaller geographic area than the broader ADDM Network. Early ADDM ASD surveillance is conducted in two phases using the same methods and project staff members as the ADDM Network. The first phase consists of reviewing and abstracting data from children's records, including comprehensive evaluations performed by community professionals. Sources for these evaluations include general pediatric health clinics and specialized programs for children with developmental disabilities. In addition, special education records (for children aged >= 3 years) were reviewed for Arizona, Colorado, New Jersey, North Carolina, and Utah, and early intervention records (for children aged 0 to = 60% data on cognitive test scores (Arizona, New Jersey, North Carolina, and Utah), the frequency of co-occurring intellectual disabilities was significantly higher among children aged 4 years than among those aged 8 years for each site in each surveillance year except Arizona in 2010. The percentage of children with ASD who had a first evaluation by age 36 months ranged from 48.8% in Missouri in 2012 to 88.9% in Wisconsin in 2014. The percentage of children with a previous ASD diagnosis from a community provider varied by site, ranging from 43.0% for Arizona in 2012 to 86.5% for Missouri in 2012. The median age at earliest known ASD diagnosis varied from 28 months in North Carolina in 2014 to 39.0 months in Missouri and Wisconsin in 2012. In 2014, the ASD prevalence based on the DSM-IV-TR case definition was 20% higher than the prevalence based on the DSM-5 (17.0 versus 14.1 per 1,000, respectively). Trends in ASD prevalence and characteristics among children aged 4 years during the study period were assessed for the three sites with data for all 3 years and consistent data sources (Arizona, Missouri, and New Jersey) using the DSM-IV-TR case definition; prevalence was higher in 2014 than in 2010 among children aged 4 years in New Jersey and was stable in Arizona and Missouri. In Missouri, ASD prevalence was higher among children aged 8 years than among children aged 4 years. The percentage of children with ASD who had a comprehensive evaluation by age 36 months was stable in Arizona and Missouri and decreased in New Jersey. In the three sites, no change occurred in the age at earliest known ASD diagnosis during 2010-2014. Interpretation: The findings suggest that ASD prevalence among children aged 4 years was higher in 2014 than in 2010 in one site and remained stable in others. Among children with ASD, the frequency of cognitive impairment was higher among children aged 4 years than among those aged 8 years and suggests that surveillance at age 4 years might more often include children with more severe symptoms or those with co-occurring conditions such as intellectual disability. In the sites with data for all years and consistent data sources, no change in the age at earliest known ASD diagnosis was found, and children received their first developmental evaluation at the same or a later age in 2014 compared with 2010. Delays in the initiation of a first developmental evaluation might adversely affect children by delaying access to treatment and special services that can improve outcomes for children with ASD. Public Health Action: Efforts to increase awareness of ASD and improve the identification of ASD by community providers can facilitate early diagnosis of children with ASD. Heterogeneity of results across sites suggests that community-level differences in evaluation and diagnostic services as well as access to data sources might affect estimates of ASD prevalence and age of identification. Continuing improvements in providing developmental evaluations to children as soon as developmental concerns are identified might result in earlier ASD diagnoses and earlier receipt of services, which might improve developmental outcomes.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Notions of agency in early literacy classrooms: assemblages and productive intersections

Agency and its role in the early literacy classroom has long been a topic for debate. While sociocultural accounts often portray the child as a cultural agent who negotiates their own participation in classroom culture and literacy learning, more recent framings draw attention from the individual subject, instead seeing agency as dispersed across people and materials. In this article I draw on my experiences of following children as they followed their interests in an early literacy classroom, drawing on the concepts of assemblage and people yet to come, as defined by Deleuze and Guattari and Spinoza’s common notion. I provide one illustrative account of moment-by-moment activity and suggest that in education settings it is useful to see activity as a direct and ongoing interplay of three dimensions: children’s moving bodies; the classroom; and its materials. I propose that children’s ongoing movements create possibilities for ‘doing’ and ‘being’ that flow across and between children. I argue that thinking with assemblage can draw attention to both the potentiality and the power dynamics inherent in the ongoing present and also counter preconceived notions of individual child agency and linear trajectories of literacy development, and the inequalities this these concepts can perpetuate within early education settings

Healthcare professional preferences in the health and fitness assessment and optimization of older patients facing colorectal cancer surgery

Abstract: Aim: There are few age‐ and fitness‐specific, evidence‐based guidelines for colorectal cancer surgery. The uptake of different assessment and optimization strategies is variable. The aim of this study was to explore healthcare professional opinion about these issues using a mixed methods design. Methods: Semi‐structured qualitative interviews were undertaken with healthcare professionals from a single UK region involved in the treatment, assessment and optimization of colorectal surgery patients. Interviews were analysed using the framework approach. An online questionnaire survey was subsequently designed and disseminated to UK surgeons to quantitatively assess the importance of interview themes. Descriptive statistics were used to analyse questionnaire data. Results: Thirty‐seven healthcare professionals out of 42 approached (response rate 88%) were interviewed across five hospitals in the south Yorkshire region. Three broad themes were developed: attitudes towards treatment of the older patient, methods of assessment of suitability and optimization strategies. The questionnaire was completed by 103 out of an estimated 256 surgeons (estimated response rate 40.2%). There was a difference in opinion regarding the role of major surgery in older patients, particularly when there is coexisting dementia. Assessment was not standardized. Access to optimization strategies was limited, particularly in the emergency setting. Conclusion: There is wide variation in the process of assessment and provision of optimization strategies in UK practice. Lack of evidence‐based guidelines, cost and time constraints restrict the development of services and pathways. Differences in opinion between surgeons towards patients with frailty or dementia may account for some of the variation in colorectal cancer outcomes

Why do women not use antenatal services in low and middle income countries? A metasynthesis of qualitative studies

Background: Almost 50% of women in low & middle income countries (LMIC’s) don’t receive adequate antenatal care. Women’s views can offer important insights into this problem. Qualitative studies exploring inadequate use of antenatal services have been undertaken in a range of countries, but the findings are not easily transferable. We aimed to inform the development of future antenatal care programmes through a synthesis of findings in all relevant qualitative studies. Methods and Findings: Using a pre-determined search strategy, we identified robust qualitative studies reporting on the views and experiences of women in LMIC’s who received inadequate antenatal care. We used meta-ethnographic techniques to generate themes and a line of argument synthesis. We derived policy relevant hypotheses from the findings. We included 21 papers representing the views of more than 1230 women from 15 countries. Three key themes were identified: ‘Pregnancy as socially risky and physiologically healthy’; ‘Resource use and survival in conditions of extreme poverty’and ‘Not getting it right first time’. The line of argument synthesis describes a dissonance between programme design and cultural contexts that may restrict access and discourage return visits. We hypothesize that centralized, risk-focused antenatal care programmes may be at odds with the resources, beliefs and experiences of pregnant women who underuse antenatal services. Conclusions: Our findings suggest that there may be a mis-alignment between current antenatal provision and the social and cultural context of some women in LMIC’s. Antenatal care provision that is theoretically and contextually at odds with local contextual beliefs and experiences are likely to be underused, especially when attendance generates increased personal risks of lost family resource or physical danger during travel; when the promised care is not delivered due to resource constraints; and when women experience covert or overt abuse in care settings