Molecular simulations of heterogeneous ice nucleation. II. Peeling back the layers

Coarse grained molecular dynamics simulations are presented in which the sensitivity of the ice nucleation rate to the hydrophilicity of a graphene nanoflake is investigated. We find that an optimal interaction strength for promoting ice nucleation exists, which coincides with that found previously for a face centered cubic (111) surface. We further investigate the role that the layering of interfacial water plays in heterogeneous ice nucleation and demonstrate that the extent of layering is not a good indicator of ice nucleating ability for all surfaces. Our results suggest that to be an efficient ice nucleating agent, a surface should not bind water too strongly if it is able to accommodate high coverages of water

Molecular simulations of heterogeneous ice nucleation. I. Controlling ice nucleation through surface hydrophilicity

Ice formation is one of the most common and important processes on earth and almost always occurs at the surface of a material. A basic understanding of how the physicochemical properties of a material’s surface affect its ability to form ice has remained elusive. Here, we use molecular dynamics simulations to directly probe heterogeneous ice nucleation at a hexagonal surface of a nanoparticle of varying hydrophilicity. Surprisingly, we find that structurally identical surfaces can both inhibit and promote ice formation and analogous to a chemical catalyst, it is found that an optimal interaction between the surface and the water exists for promoting ice nucleation. We use our microscopic understanding of the mechanism to design a modified surface in silico with enhanced ice nucleating ability

The Functionality of Mobile Apps for Anxiety: Systematic Search and Analysis of Engagement and Tailoring Features

BACKGROUND: A range of mobile apps for anxiety have been developed in response to the high prevalence of anxiety disorders. Although the number of publicly available apps for anxiety is increasing, attrition rates among mobile apps are high. These apps must be engaging and relevant to end users to be effective; thus, engagement features and the ability to tailor delivery to the needs of individual users are key. However, our understanding of the functionality of these apps concerning engagement and tailoring features is limited. OBJECTIVE: The aim of this study is to review how cognitive behavioral elements are delivered by anxiety apps and their functionalities to support user engagement and tailoring based on user needs. METHODS: A systematic search for anxiety apps described as being based on cognitive behavioral therapy (CBT) was conducted on Android and iPhone marketplaces. Apps were included if they mentioned the use of CBT for anxiety-related disorders. We identified 597 apps, of which 36 met the inclusion criteria and were reviewed through direct use. RESULTS: Cognitive behavioral apps for anxiety incorporate a variety of functionalities, offer several engagement features, and integrate low-intensity CBT exercises. However, the provision of features to support engagement is highly uneven, and support is provided only for low-intensity CBT treatment. Cognitive behavioral elements combine various modalities to deliver intervention content and support the interactive delivery of these elements. Options for personalization are limited and restricted to goal selection upon beginning use or based on self-monitoring entries. Apps do not appear to provide individualized content to users based on their input. CONCLUSIONS: Engagement and tailoring features can be significantly expanded in existing apps, which make limited use of social features and clinical support and do not use sophisticated features such as personalization based on sensor data. To guide the evolution of these interventions, further research is needed to explore the effectiveness of different types of engagement features and approaches to tailoring therapeutic content

Understanding users’ perspectives on mobile apps for anxiety management

Anxiety disorders are the most common type of mental health problem. The potential of apps to improve mental health has led to an increase in the number of anxiety apps available. Even though anxiety apps hold the potential to enhance mental health care for individuals, there is relatively little knowledge concerning users’ perspectives. This mixed-methods study aims to understand the nature of user burden and engagement with mental health apps (MHapps) targeting anxiety management, in order to identify ways to improve the design of these apps. Users’ perspectives on these apps were gathered by analyzing 600 reviews from 5 apps on the app stores (Study 1), and conducting 15 interviews with app users (Study 2). The results shed light on several barriers to adoption and sustained use. Users appreciate apps that offer content variation, customizability, and good interface design, and often requested an enhanced, personalized experience to improve engagement. We propose addressing the specific app quality issues identified through human-centered design, more personalized content delivery, and by improving features for social and therapeutic support

Identity tags: A vector for cross-infection?

Background. Nosocomial infections represent one of the challenging problems of modern medicine. Healthcare providers play an important role in the transmission of these infections on their hands, clothing and equipment. Modern security systems require personnel to wear clearly displayed identity (ID) tags, and to have an easily accessible access disc. These access and ID tags are often worn around the neck on a lanyard, and could possibly harbour bacteria and be a vector for cross-infection.Method. Saline-moistened swabs of the front and back of ID tags of 50 healthcare workers were taken for bacterial culture. Swabs were inoculated onto standard microbiological media. Potential pathogens were subjected to sensitivity testing while organisms resembling normal skin commensals were reported as such.Results. Twenty-eight of the 50 (56%) ID swabs cultured exhibited no bacterial growth. Eighteen (36%) swabs grew primarily skin flora. Neutrophils were observed under microscopy on two (4%) swabs. Seven (14%) swabs grew potentially pathogenic bacteria. Doctors were found to have almost three times the risk of carrying pathogenic bacteria on their ID tags compared with nurses. Recent patient contact also showed a higher incidence of colonisation. There were no statistically significant differences between variables such as ward or area of work, nature of patient contact, time since qualification, level of qualification or length of employment at Red Cross War Memorial Children’s Hospital, Cape Town, South Africa.Conclusions. Prevention of hospital-acquired infections is important in any setting. The ID tag has been identified as a possible source of infection spread in this and previous studies. The ID tag has to date been neglected as a potential source of pathogen spread, and efforts to make staff aware of this potential danger should be considered in every institution

Designing personalized mental health interventions for anxiety: CBT therapists’ perspective

Anxiety disorders are the most common mental health problem, and cognitive-behavioral therapy is one of the most widely used, evidence-based treatments. While several mobile apps for anxiety that integrate cognitive-behavioral therapy (CBT) techniques exist, major challenges remain concerning uptake and engagement. Personalization is one strategy that can be used to improve client engagement, and integrating therapist input is one mechanism for such personalization. This study aims to understand therapist practices and identify new possibilities for delivering intervention content between face-to-face CBT therapy sessions. It comprised semi-structured interviews, followed by a series of ideation activities, and thematic analysis of the data. The results showed the central role of clients in shaping the content of therapy sessions, their challenges with homework practice, and therapists’ diverse practices. Analysis of the ideation activities elaborated the potential role of therapists in the personalization of apps for anxiety. We conclude with takeaways for designers of personalized mental health mobile applications

Validation of walking speed estimation from trunk mounted accelerometers for a range of walking speeds

Walking speed is a strong indicator of the health status of older people and patients. Using algorithms, the walking speed can be estimated from wearable accelerometers, which enables min-imally obtrusive (longitudinal) monitoring. We evaluated the performance of two algorithms, the inverted pendulum (IP) algorithm, and a novel adaptation correcting for lateral step movement, which aimed to improve accuracy during slow walking. To evaluate robustness, we gathered data from different groups (healthy adults, elderly, and elderly patients) of volunteers (n = 159) walking under various conditions (over ground, treadmill, using walking aids) at a broad range of speeds (0.11–1.93 m/s). Both of the algorithms showed good agreement with the reference values and sim-ilar root-mean-square errors (RMSEs) for walking speeds ≥0.5 m/s, which ranged from 0.09–0.16 m/s for the different positions, in line with the results from others. However, for slower walking, RMSEs were significantly better for the new method (0.06–0.09 m/s versus 0.15–0.19 m/s). Pearson correlation improved for speeds <0.5 m/s (from 0.67–0.72 to 0.73–0.82) as well as higher speeds (0.87– 0.97 to 0.90–0.98) with the new method. Overall, we found that IP(-based) walking speed estimation proved to be applicable for a variety of wearing positions, conditions and speeds, indicating its potential value for health assessment applications

Self-reported body fat change in HIV-infected men is a marker of decline in physical health-related quality of life with aging, independent of co-morbidity

Objective: Self-perception of changes in body fat among HIV+ persons is associated with decreased health related quality of life in cross-sectional studies. The longitudinal impact of body fat changes on health related quality of life, while accounting for comorbidity and anatomic location or severity of body fat changes, is unknown. Design: This was a longitudinal analysis of HIV+ and HIV- Multicenter AIDS Cohort Study (MACS) participants who completed questionnaires assessing self-perceived body fat changes (baseline visit) and a health related quality of life (Short Form-36) at baseline and then ≥5 years later. Methods: Relationships between body fat changes and change in Short Form-36 Physical and Mental Component Summary scores were investigated using mixedmodel regression. Results: We studied 270 HIV+ and 247 HIV- men. At baseline, ≥50% of HIV+ men reported body fat changes; physical component but not mental component summary scores were lower among HIV+ men who reported moderate/severe leg or abdominal fat changes (p<0.05). At follow-up, physical component summary scores were significantly lower among men with face, leg, or abdominal fat changes compared to men without perceived fat changes (p<0.05). No significant changes were seen in mental component scores by fat change location or severity. In the final model, body fat changes at any site or severity were significant predictors of a decline in physical component summary score (p<0.05), independent of demographics or comorbidities. Mental component summary score was not associated with body fat changes, but higher mental component summary score was associated with increasing age and time. Conclusions: Negative self-perceived body fat changes were associated with decline in physical health related quality of life, independent of comorbidities, and may be a marker of an increased risk for physical function decline with aging

Sliding charge density wave in manganites

The so-called stripe phase of the manganites is an important example of the complex behaviour of metal oxides, and has long been interpreted as the localisation of charge at atomic sites. Here, we demonstrate via resistance measurements on La_{0.50}Ca_{0.50}MnO_3 that this state is in fact a prototypical charge density wave (CDW) which undergoes collective transport. Dramatic resistance hysteresis effects and broadband noise properties are observed, both of which are typical of sliding CDW systems. Moreover, the high levels of disorder typical of manganites result in behaviour similar to that of well-known disordered CDW materials. Our discovery that the manganite superstructure is a CDW shows that unusual transport and structural properties do not require exotic physics, but can emerge when a well-understood phase (the CDW) coexists with disorder.Comment: 13 pages; 4 figure

Social and ecological effectiveness of large marine protected areas

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Large marine protected areas are increasingly being established to meet global conservation targets and promote sustainable use of resources. Although the factors affecting the performance of small-scale marine protected areas are relatively well studied, there is no such body of knowledge for large marine protected areas. We conducted a global meta-analysis to systematically investigate social, ecological, and governance characteristics of successful large marine protected areas with respect to several social and ecological outcomes. We included all large (>10,000km2), implemented (>5 years of active management) marine protected areas that had sufficient data for analysis, for a total of twelve cases. We used the Social-Ecological Systems Meta-Analysis Database, and a consistent protocol for using secondary data and key informant interviews, to code proxies for fisheries, ecosystem health, and the wellbeing of user groups (mainly fishers). We tested four sets of hypotheses derived from the literature on smallscale marine protected areas and common-pool resources: (i) the attributes of species and ecosystems to be managed in the marine protected area, (ii) adherence to principles for designing small-scale marine protected areas, (iii) adherence to the design principles for common-pool resource management, and (iv) stakeholder participation. We found varying levels of support for these hypotheses. Improved fisheries were associated with older marine protected areas, and higher levels of enforcement. Declining fisheries were associated with several ecological and economic factors, including low productivity, high mobility, and high market value. High levels of participation were correlated with improvements in wellbeing and ecosystem health trends. Overall, this study constitutes an important first step in identifying factors affecting social wellbeing and ecological performance of large marine protected areas.NCB thanks SSHRC and NSERC. CMB was supported by the Price Fellowship and Stanford University’s Emmett Interdisciplinary Program in Environmental Resources. GE is supported by a SSHRC postdoctoral fellowship. We gratefully acknowledge participants of our key informant interviewsThis is the author accepted manuscript. The final version is available from the publisher via the DOI in this record