A simple genetic algorithm for calibration of stochastic rock discontinuity networks

Este artículo propone un método para llevar a cabo la calibración de las familias de discontinuidades en macizos rocosos. We present a novel approach for calibration of stochastic discontinuity network parameters based on genetic algorithms (GAs). To validate the approach, examples of application of the method to cases with known parameters of the original Poisson discontinuity network are presented. Parameters of the model are encoded as chromosomes using a binary representation, and such chromosomes evolve as successive generations of a randomly generated initial population, subjected to GA operations of selection, crossover and mutation. Such back-calculated parameters are employed to make assessments about the inference capabilities of the model using different objective functions with different probabilities of crossover and mutation. Results show that the predictive capabilities of GAs significantly depend on the type of objective function considered; and they also show that the calibration capabilities of the genetic algorithm can be acceptable for practical engineering applications, since in most cases they can be expected to provide parameter estimates with relatively small errors for those parameters of the network (such as intensity and mean size of discontinuities) that have the strongest influence on many engineering applications

The appropriateness of gatekeeping in the provision of reproductive health care for adolescents in Lithuania:the general practice perspective

BACKGROUND: Adolescents' consultation of primary health care services remains problematic despite their accessibility. The reproductive health service seeking behavior of adolescents is the object of much research but little is known about how this behavior is influenced by the gatekeeping system. This study aimed to explore general practitioners' perceptions of the appropriateness of gatekeeping in adolescent reproductive health care. METHODS: Twenty in-depth interviews regarding factors affecting adolescent reproductive health care were carried out on a diverse sample of general practitioners and analyzed using grounded theory. RESULTS: The analysis identified several factors that shaped GPs' negative attitude to gatekeeping in adolescent reproductive health care. Its appropriateness in this field was questionable due to a lack of willingness on the part of GPs to provide reproductive health services for teenagers, their insufficient training, inadequately equipped surgeries and low perceived support for reproductive health service provision. CONCLUSION: Since factors for improving adolescent reproductive health concern not only physicians but also the health system and policy levels, complex measures should be designed to overcome these barriers. Discussion of a flexible model of gatekeeping, encompassing both co-ordination of care provided by GPs and the possibility of patients' self-referral, should be included in the political agenda. Adolescents tend to under-use rather than over-use reproductive health services and every effort should be made to facilitate the accessibility of such services

Using the Ages and Stages Questionnaire to teach medical students developmental assessment: a descriptive analysis

BACKGROUND: After a survey of medical graduates' skills found a lack of confidence in developmental assessment, a program was introduced with the broad aims of increasing medical student confidence and respect for the parents' role in childhood developmental assessment. Research has shown that parents' concerns are as accurate as quality screening tests in assessing development, so the program utilised the Ages and Stages Questionnaire, a parent completed, child development assessment tool. METHOD: To evaluate the program, an interpretative analysis was completed on the students' reports written during the program and a questionnaire was administered to the parents to gain their perception of the experience. As well, student confidence levels in assessing growth and development were measured at the end of the paediatric term. RESULTS: Although there was an increase in student confidence in developmental assessment at the end of the term, it was not statistically significant. However the findings indicated that students gained increased understanding of the process and enhanced recognition of the parental role, and the study suggested there was increased confidence in some students. Parents indicated that they thought they should be involved in the teaching of students. CONCLUSION: The ASQ was shown to have been useful in an education program at the level of advanced beginners in developmental assessment

Importance of proximity to resources, social support, transportation and neighborhood security for mobility and social participation in older adults: results from a scoping study

ABSTRACT: Background: Since mobility and social participation are key determinants of health and quality of life, it is important to identify factors associated with them. Although several investigations have been conducted on the neighborhood environment, mobility and social participation, there is no clear integration of the results. This study aimed to provide a comprehensive understanding regarding how the neighborhood environment is associated with mobility and social participation in older adults.Methods: A rigorous methodological scoping study framework was used to search nine databases from different fields with fifty-one keywords. Data were exhaustively analyzed, organized and synthesized according to the International Classification of Functioning, Disability and Health (ICF) by two research assistants following PRISMA guidelines, and results were validated with knowledge users.Results: The majority of the 50 selected articles report results of cross-sectional studies (29; 58 %), mainly conducted in the US (24; 48 %) or Canada (15; 30 %). Studies mostly focused on neighborhood environment associations with mobility (39; 78 %), social participation (19; 38 %), and occasionally both (11; 22 %). Neighborhood attributes considered were mainly 'Pro ducts and technology' (43; 86) and 'Services, systems and policies' (37; 74 %), but also 'Natural and human- made changes' (27; 54 %) and 'Support and relationships' (21; 42 %). Mobility and social participation were both positively associated with Proximity to resources and recreational facilities, Social support, Having a car or driver's license, Public transportation and Neighborhood security, and negatively associated with Poor user-friendliness of the walking environment and Neighborhood insecurity. Attributes of the neighborhood environment not covered by previous research on mobility and social participation mainly concerned 'Attitudes', and 'Services, systems and policies'.Conclusion: Results from this comprehensive synthesis of empirical studies on associations of the neighborhood environment with mobility and social participation will ultimately support best practices, decisions and the development of innovative inclusive public health interventions including clear guidelines for the creation of age-supportive environments. To foster mobility and social participation, these interventions must consider Proximity to resources and to recreational facilities, Social support, Transportation, Neighborhood security and User-friendliness of the walking environment. Future studies should include both mobility and social participation, and investigate how they are associated with 'Attitudes', and 'Services, systems and policies' in older adults, including disadvantaged older adults

The neighbourhood environment and use of neighbourhood resources in older adults with and without lower limb osteoarthritis:results from the Hertfordshire Cohort Study

This study aimed to examine the associations of perceptions of neighbourhood cohesion and neighbourhood problems and objectively measured neighbourhood deprivation with the use of neighbourhood resources by older adults with and without lower limb osteoarthritis (LLOA), and to assess whether these relationships are stronger in older persons with LLOA than in those without the condition. Data from the Hertfordshire Cohort Study were used. American College of Rheumatology classification criteria were used to diagnose clinical LLOA (knee and/or hip osteoarthritis). Use of neighbourhood resources was assessed using the Home and Community Environment instrument. Participants were asked about their perceptions of neighbourhood cohesion and neighbourhood problems. Objective neighbourhood deprivation was assessed using the Index of Multiple Deprivation score based on 2010 census data. Of the 401 participants (71–80 years), 74 (18.5 %) had LLOA. The neighbourhood measures were not significantly associated with use of resources in the full sample. A trend for a negative association between use of public transport and perceived neighbourhood problems was observed in participants with LLOA (OR = 0.77, 99 % CI = 0.53–1.12), whereas a trend for a positive association between perceived neighbourhood problems and use of public transport was found in participants without LLOA (OR = 1.18, 99 % CI = 1.00–1.39). The perception of more neighbourhood problems seems only to hinder older adults with LLOA to make use of public transport. Older adults with LLOA may be less able to deal with neighbourhood problems and more challenging environments than those without the condition

Protein 4.1B Contributes to the Organization of Peripheral Myelinated Axons

Neurons are characterized by extremely long axons. This exceptional cell shape is likely to depend on multiple factors including interactions between the cytoskeleton and membrane proteins. In many cell types, members of the protein 4.1 family play an important role in tethering the cortical actin-spectrin cytoskeleton to the plasma membrane. Protein 4.1B is localized in myelinated axons, enriched in paranodal and juxtaparanodal regions, and also all along the internodes, but not at nodes of Ranvier where are localized the voltage-dependent sodium channels responsible for action potential propagation. To shed light on the role of protein 4.1B in the general organization of myelinated peripheral axons, we studied 4.1B knockout mice. These mice displayed a mildly impaired gait and motility. Whereas nodes were unaffected, the distribution of Caspr/paranodin, which anchors 4.1B to the membrane, was disorganized in paranodal regions and its levels were decreased. In juxtaparanodes, the enrichment of Caspr2, which also interacts with 4.1B, and of the associated TAG-1 and Kv1.1, was absent in mutant mice, whereas their levels were unaltered. Ultrastructural abnormalities were observed both at paranodes and juxtaparanodes. Axon calibers were slightly diminished in phrenic nerves and preterminal motor axons were dysmorphic in skeletal muscle. βII spectrin enrichment was decreased along the axolemma. Electrophysiological recordings at 3 post-natal weeks showed the occurrence of spontaneous and evoked repetitive activity indicating neuronal hyperexcitability, without change in conduction velocity. Thus, our results show that in myelinated axons 4.1B contributes to the stabilization of membrane proteins at paranodes, to the clustering of juxtaparanodal proteins, and to the regulation of the internodal axon caliber

User Experiences of Development of Dependence on the Synthetic Cannabinoids, 5f-AKB48 and 5F-PB-22, and Subsequent Withdrawal Syndromes

Emergence of synthetic cannabinoids (SCBs) in herbal smoking mixtures is a public health concern. New SCB’s such as 5f-AKB48 and 5F-PB-22 have been detected in French seizures and in sudden death post mortems in the US. The aim was to describe development of dependence on herbal smoking mixtures containing the SCB’s, 5f-AKB48 and 5F-PB-22 and subsequent withdrawal syndromes. Dependent users of herbal smoking mixtures known to contain the SCB’s 5f-AKB48 and 5F-PB-22 with an average Severity of Dependence Score (SDS) of 13 were interviewed using a structured guide (three males/three females). Narratives were analysed using the Empirical Phenomenological Psychological (EPP) five step method. Six themes with 68 categories emerged from the analysis. Themes are illustrated as 1) Networks and Product Availability; 2) Drivers and Motives for Use; 3) Effect and Pathways toward Dependence; 4) Poly Substance Use and Comparisons to Natural Cannabis; 5) Dependence and Withdrawal and 6) Self-detoxification Attempts. Two higher levels of abstraction above these theme-levels emerged from the data, with sole use of herbal smoking mixtures containing 5f-AKB48 and 5F-PB-22 centering on the interplay between intense cravings, compulsive all-consuming seeking, use and re-dose behaviours, and fear of the psychiatric and self-harms caused when in withdrawal. This is the first study describing dependence and withdrawal experiences in users dependent on 5f-AKB48 and 5F-PB-22. Given the potential for adverse psychiatric and physical consequences of dependent use, further development of specific clinical responses and clinical research around toxicity and withdrawal severity are warranted