The Euler spiral of rat whiskers

This paper reports on an analytical study of the intrinsic shapes of 523 whiskers from 15 rats. We show that the variety of whiskers on a rat’s cheek, each of which has different lengths and shapes, can be described by a simple mathematical equation such that each whisker is represented as an interval on the Euler spiral. When all the representative curves of mystacial vibrissae for a single rat are assembled together, they span an interval extending from one coiled domain of the Euler spiral to the other. We additionally find that each whisker makes nearly the same angle of 47∘ with the normal to the spherical virtual surface formed by the tips of whiskers, which constitutes the rat’s tactile sensory shroud or “search space.” The implications of the linear curvature model for gaining insight into relationships between growth, form, and function are discussed

Morphological peculiarities of a harbour seal (Phoca vitulina) whisker revealed by normal skeletonisation.

Of all mammalian vibrissae, those of certain species of pinnipeds are exceptional. Researchers believe that their curious undulating form evolved for hydrodynamic detection. Our understanding of how these whiskers work depends on a geometrical model that captures the crucial pertinent features of the natural vibrissae including its tapering and curvature. It should also account for the form of the whisker when it flexes under external loading. We introduce and study a normal skeleton of a two-dimensional projection of a harbour seal whisker. The normal skeleton is a complete shape descriptor that involves reduction to the centreline equipped with a thickness function of the orthogonal cross-section. The contours of the whisker shape are extracted from a 2D greyscale scan. Our analysis reveals correspondence between the undulations of the width and oscillations of the centreline curvature as functions of arc length. We discuss two possible explanations for that remarkable feature: one based on consideration of growth and the other of plastic deformation. For the latter we employ a mechanical model to demonstrate appearance of curvature oscillations caused by extensive deflection of the undulating whisker due to external loading

Nano-structured magnetic metamaterial with enhanced nonlinear properties

Nano-structuring can significantly modify the properties of materials. We demonstrate that size-dependent modification of the spin-wave spectra in magnetic nano-particles can affect not only linear, but also nonlinear magnetic response. The discretization of the spectrum removes the frequency degeneracy between the main excitation mode of a nano-particle and the higher spin-wave modes, having the lowest magnetic damping, and reduces the strength of multi-magnon relaxation processes. This reduction of magnon-magnon relaxation for the main excitation mode leads to a dramatic increase of its lifetime and amplitude, resulting in the intensification of all the nonlinear processes involving this mode. We demonstrate this experimentally on a two-dimensional array of permalloy nano-dots for the example of parametric generation of a sub-harmonic of an external microwave signal. The characteristic lifetime of this sub-harmonic is increased by two orders of magnitude compared to the case of a continuous magnetic film, where magnon-magnon relaxation limits the lifetime

Representações sociais sobre hipertensão arterial e o cuidado: o discurso do sujeito coletivo

OBJETIVO: Analisar as representações sociais da equipe de saúde sobre a hipertensão arterial e a maneira como desenvolvem os cuidados específicos aos hipertensos. MÉTODOS: Utilizou-se a entrevista semiestruturada com 21 profissionais de saúde que atuavam em Unidades Básicas de Saúde, a técnica do discurso do sujeito coletivo para organização dos dados e interpretação pela teoria das representações sociais. RESULTADOS: As representações dos profissionais revelaram um distanciamento entre as ações preconizadas pelo programa de controle e as que se realizam nas unidades de saúde. CONCLUSÕES: Os profissionais reconhecem a hipertensão como uma doença grave, com grandes consequências, porém as dificuldades estruturais por parte dos serviços, aliadas à desmotivação do usuário para participação em ações de promoção em saúde, não favorecem um cuidado em saúde voltado para as necessidades dos portadores de hipertensão. Tais resultados indicam a necessidade de ações interdisciplinares na prática assistencial que impactem positivamente na oferta e qualidade dos cuidados.OBJETIVO: Analizar las representaciones sociales del equipo de salud sobre la hipertensión arterial y la manera cómo desarrollan los cuidados específicos a los hipertensos. MÉTODOS: Se utilizó la entrevista semiestructurada con 21 profesionales de salud que actuaban en Unidades Básicas de Salud, la técnica del discurso del sujeto colectivo para la organización de los datos e interpretación por la teoría de las representaciones sociales. RESULTADOS: Las representaciones de los profesionales revelaron un distanciamiento entre las acciones preconizadas por el programa de control y las que se realizan en las unidades de salud. CONCLUSIONES: Los profesionales reconocen a la hipertensión como una enfermedad grave, con grandes consecuencias, sin embargo las dificultades estructurales por parte de los servicos, aliadas a la desmotivación del usuario para participar en acciones de promoción en salud, no favorecen a un cuidado en salud volcado a las necesidades de los portadores de hipertensión. Tales resultados indican la necesidad de acciones interdisciplinaris en la práctica asistencial que impacten positivamente en el ofrecimiento y calidad de los cuidados.OBJECTIVE: To analyze the social representations of the health team about arterial hypertension and the manner that develops specific care with hypertensive patients. METHODS: We used semi-structured interviews with 21 health professionals who worked in the Basic Health Units. The technique of collective subject discourse was used for organization and interpretation of the data, using the theory of social representation. RESULTS: The representations of health professionals showed a gap between the actions recommended by the control program and those taking place in health facilities. CONCLUSIONS: Professionals recognized hypertension as a serious disease, with great consequences, but the structural difficulties for part of the services, together with the user's motivation to participate in activities to promote health, did not favor health care focused on the needs of those suffering with hypertension. These results indicate the need for interdisciplinary actions in care practice that impact positively on the delivery and quality of care

Inheritance of fertility in broiler chickens

This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Phenotypic and Genetic Divergence among Poison Frog Populations in a Mimetic Radiation

The evolution of Müllerian mimicry is, paradoxically, associated with high levels of diversity in color and pattern. In a mimetic radiation, different populations of a species evolve to resemble different models, which can lead to speciation. Yet there are circumstances under which initial selection for divergence under mimicry may be reversed. Here we provide evidence for the evolution of extensive phenotypic divergence in a mimetic radiation in Ranitomeya imitator, the mimic poison frog, in Peru. Analyses of color hue (spectral reflectance) and pattern reveal substantial divergence between morphs. However, we also report that there is a “transition-zone� with mixed phenotypes. Analyses of genetic structure using microsatellite variation reveals some differentiation between populations, but this does not strictly correspond to color pattern divergence. Analyses of gene flow between populations suggest that, while historical levels of gene flow were low, recent levels are high in some cases, including substantial gene flow between some color pattern morphs. We discuss possible explanations for these observations

Photovoltaic restoration of sight with high visual acuity

Patients with retinal degeneration lose sight due to the gradual demise of photoreceptors. Electrical stimulation of surviving retinal neurons provides an alternative route for the delivery of visual information. We demonstrate that subretinal implants with 70-μm-wide photovoltaic pixels provide highly localized stimulation of retinal neurons in rats. The electrical receptive fields recorded in retinal ganglion cells were similar in size to the natural visual receptive fields. Similarly to normal vision, the retinal response to prosthetic stimulation exhibited flicker fusion at high frequencies, adaptation to static images and nonlinear spatial summation. In rats with retinal degeneration, these photovoltaic arrays elicited retinal responses with a spatial resolution of 64 ± 11 μm, corresponding to half of the normal visual acuity in healthy rats. The ease of implantation of these wireless and modular arrays, combined with their high resolution, opens the door to the functional restoration of sight in patients blinded by retinal degeneration

F- and G-Actin Concentrations in Lamellipodia of Moving Cells

Cells protrude by polymerizing monomeric (G) into polymeric (F) actin at the tip of the lamellipodium. Actin filaments are depolymerized towards the rear of the lamellipodium in a treadmilling process, thereby supplementing a G-actin pool for a new round of polymerization. In this scenario the concentrations of F- and G-actin are principal parameters, but have hitherto not been directly determined. By comparing fluorescence intensities of bleached and unbleached regions of lamellipodia in B16-F1 mouse melanoma cells expressing EGFP-actin, before and after extraction with Triton X-100, we show that the ratio of F- to G-actin is 3.2+/−0.9. Using electron microscopy to determine the F-actin content, this ratio translates into F- and G-actin concentrations in lamellipodia of approximately 500 µM and 150 µM, respectively. The excess of G-actin, at several orders of magnitude above the critical concentrations at filament ends indicates that the polymerization rate is not limited by diffusion and is tightly controlled by polymerization/depolymerization modulators

Comparison of total parathyroidectomy without autotransplantation and without thymectomy versus total parathyroidectomy with autotransplantation and with thymectomy for secondary hyperparathyroidism: TOPAR PILOT-Trial

<p>Abstract</p> <p>Background</p> <p>Secondary hyperparathyroidism (sHPT) is common in patients with chronic renal failure. Despite the initiation of new therapeutic agents, several patients will require parathyroidectomy (PTX). Total PTX with autotransplantation of parathyroid tissue (TPTX+AT) and subtotal parathyroidectomy (SPTX) are currently considered as standard surgical procedures in the treatment of sHPT. Recurrencerates after TPTX+AT or SPTX are between 10% and 12% (median follow up: 36 months).</p> <p>Recent retrospective studies demonstrated a lower rate of recurrent sHPT of 0–4% after PTX without autotransplantation and thymectomy (TPTX) with no higher morbidity when compared to the standard procedures. The observed superiority of TPTX is flawed due to different definitions of outcomes, varying follow up periods and different surgical treatment strategies (with and without thymectomy).</p> <p>Methods/Design</p> <p>Patients with sHPT (intact parathyroid hormone > 10 times above the upper limit of normal) on long term dialysis (>12 months) will be randomized either to TPTX or TPTX+AT and followed for 36 months. Outcome parameters are recurrence rates of sHPT, frequencies of reoperations due to refractory hypoparathyroidism or recurrent/persistent hyperparathyroidism, postoperative morbidity and mortality and quality of life. 50 patients per group will be randomized in order to obtain relevant frequencies of outcome parameters that will form the basis for a large scale confirmatory multicentred randomized controlled trial.</p> <p>Discussion</p> <p>sHPT is a disease with a high incidence in patients with chronic renal failure. Even a small difference in outcomes will be of clinical relevance. To assess sufficient data about the rate of recurrent sHPT after both methods, a multicentred, randomized controlled trial (MRCT) under standardized conditions is mandatory.</p> <p>Due to the existing uncertainties the calculated number of patients necessary in each treatment arm (n > 4000) makes it impossible to perform this study as a confirmatory trial. Therefore estimates of different outcomes are performed using a pilot MRCT comparing 50 versus 50 randomized patients in order to establish a hypothesis that can be tested thereafter.</p> <p>If TPTX proves to have a lower rate of recurrent sHPT, no relevant disadvantages and no higher morbidity than TPTX+AT, current surgical practice may be changed.</p> <p>Trial registration</p> <p>International Standard Randomized Controlled Trial Number Registration (ISRCTN86202793)</p

Interventions targeting social isolation in older people: a systematic review

This is a freely-available open access publication. Please cite the published version which is available via the DOI link in this record.BACKGROUND: Targeting social isolation in older people is a growing public health concern. The proportion of older people in society has increased in recent decades, and it is estimated that approximately 25% of the population will be aged 60 or above within the next 20 to 40 years. Social isolation is prevalent amongst older people and evidence indicates the detrimental effect that it can have on health and wellbeing. The aim of this review was to assess the effectiveness of interventions designed to alleviate social isolation and loneliness in older people. METHODS: Relevant electronic databases (MEDLINE, EMBASE, ASSIA, IBSS, PsycINFO, PubMed, DARE, Social Care Online, the Cochrane Library and CINAHL) were systematically searched using an extensive search strategy, for randomised controlled trials and quasi-experimental studies published in English before May 2009. Additional articles were identified through citation tracking. Studies were included if they related to older people, if the intervention aimed to alleviate social isolation and loneliness, if intervention participants were compared against inactive controls and, if treatment effects were reported. Two independent reviewers extracted data using a standardised form. Narrative synthesis and vote-counting methods were used to summarise and interpret study data. RESULTS: Thirty two studies were included in the review. There was evidence of substantial heterogeneity in the interventions delivered and the overall quality of included studies indicated a medium to high risk of bias. Across the three domains of social, mental and physical health, 79% of group-based interventions and 55% of one-to-one interventions reported at least one improved participant outcome. Over 80% of participatory interventions produced beneficial effects across the same domains, compared with 44% of those categorised as non-participatory. Of interventions categorised as having a theoretical basis, 87% reported beneficial effects across the three domains compared with 59% of interventions with no evident theoretical foundation. Regarding intervention type, 86% of those providing activities and 80% of those providing support resulted in improved participant outcomes, compared with 60% of home visiting and 25% of internet training interventions. Fifty eight percent of interventions that explicitly targeted socially isolated or lonely older people reported positive outcomes, compared with 80% of studies with no explicit targeting. CONCLUSIONS: More, well-conducted studies of the effectiveness of social interventions for alleviating social isolation are needed to improve the evidence base. However, it appeared that common characteristics of effective interventions were those developed within the context of a theoretical basis, and those offering social activity and/or support within a group format. Interventions in which older people are active participants also appeared more likely to be effective. Future interventions incorporating all of these characteristics may therefore be more successful in targeting social isolation in older people.National Institute for Health Researc