Statistical translation invariance protects a topological insulator from interactions

We investigate the effect of interactions on the stability of a disordered, two-dimensional topological insulator realized as an array of nanowires or chains of magnetic atoms on a superconducting substrate. The Majorana zero-energy modes present at the ends of the wires overlap, forming a dispersive edge mode with thermal conductance determined by the central charge $c$ of the low-energy effective field theory of the edge. We show numerically that, in the presence of disorder, the $c=1/2$ Majorana edge mode remains delocalized up to extremely strong attractive interactions, while repulsive interactions drive a transition to a $c=3/2$ edge phase localized by disorder. The absence of localization for strong attractive interactions is explained by a self-duality symmetry of the statistical ensemble of disorder configurations and of the edge interactions, originating from translation invariance on the length scale of the underlying mesoscopic array.Comment: 5+2 pages, 8 figure

Postural Control in Preschool Children with Developmental Coordination Disorder, in Sitting Position During a Functional Task

The developmental coordination disorder is a motor disorder that affects 5 to 6% of children at school-age. The postural control deficit is one of the most prevalent problems affecting 73 to 87% of these children. The present research aims to analyze and compare postural control in probable (p-DCD) and at- risk of developmental coordination disorder children and in typical children in a sitting position during a functional task. p-DCD children were tendentially less recurrent, less periodic, simpler and more regular. These children oscillated more and faster in conditions with visual information; with a visual focus they had more stability and oscillated less and slowler campared to the baseline; without visual information they reduced their oscillations and velocity and become less recurrent, periodic, stable and simpler, possibly freenzing more degrees of freedom in order to respond to absence of external information. p-DCD seem to be more dependent on external stimulus like visual information to auto organize their own balance. The greater the task’s complexity, the lesser and slower their oscillations were but also more recurrent and periodic. Despite oscillating, more and faster in all conditions and being tendentially more recurrent and periodic, in risk children revealed a behaviour pattern similar to typical in both variables. p-DCD, at-risk and typical children reveal the same manner of action without visual information, less and slower oscillations. Most likely, the problem with p-DCD is not in motor control, but on perception-action cycles’ effectivness; and, where stimulation must be focused.info:eu-repo/semantics/publishedVersio

Novel functions for Rab GTPases in multiple aspects of tumour progression

Rab GTPases are master regulators of intracellular trafficking and, in recent years, their role in the control of different aspects of tumour progression has emerged. In the present review, we show that Rab GTPases are disregulated in many cancers and have central roles in tumour cell migration, invasion, proliferation, communication with stromal cells and the development of drug resistance. As a consequence, Rab proteins may be novel potential candidates for the development of anticancer drugs and, in this context, the preliminary results obtained with an inhibitor of Rab function are also discussed

The pursuit of skin pigmentation control mechanisms

Funding: We would like to thank our group for critical reading of the manuscript. This work was supported by Fundação para a Ciência e a Tecnologia (FCT) through projects EXPL/BEXBCM/0379/2013 and PTDC/BIA-CEL/29765/2017. H.M. was supported by a PhD fellowship from FCT (PD/BD/114118/2015), and D.C.B. by the FCT Investigator Program (IF/00501/2014/CP1252/ CT0001). This article is supported by the LYSOCIL project. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 811087.The mechanisms by which the pigment melanin is transferred from melanocytes and processed within keratinocytes to achieve skin pigmentation remain ill-characterized. Nevertheless, several models have emerged in the past decades to explain the transfer process. Here, we review the proposed models for melanin transfer in the skin epidermis, the available evidence supporting each one, and the recent observations in favor of the exo/phagocytosis and shed vesicles models. In order to reconcile the transfer models, we propose that different mechanisms could co-exist to sustain skin pigmentation under different conditions. We also discuss the limited knowledge about melanin processing within keratinocytes. Finally, we pinpoint new questions that ought to be addressed to solve the long-lasting quest for the understanding of how basal skin pigmentation is controlled. This knowledge will allow the emergence of new strategies to treat pigmentary disorders that cause a significant socio-economic burden to patients and healthcare systems worldwide and could also have relevant cosmetic applications.publishersversionpublishe

In and out and out again: The travails of Brazil as a security provider in Africa

The story of Brazil as a contemporary security actor in Africa can prove a peculiar one. Marked by quick gains and an equally quick recognition over a short period of time, it has also been followed by an equally quick turnaround which has led, as of 2020, to a visible disengagement on the ground. We explore the main travails in this domain, which have compromised much of the gains previously obtained throughout the continent. The chapter begins with a general balance of the progress achieved between 2003 and 2016, followed by the highlights of the recent downturn. We then analyze a specific sub-area, namely, the inroads carried out at the defence industry level, in order to showcase the promises and contradictions often associated to what the country has offered across the Atlantic. We conclude by presenting some opportunities for a new pickup of Brazilian interest in the middle and long run

Exploratory study on maturation and competition level in young karate practitioners

Emparelhar crianças propicia sucesso e reduz lesões no desporto. Apesar das diferenças de maturação entre crianças, a idade cronológica mantém-se o principal critério para equalizar os níveis de competição, mas com uma eficiência limitada. No entanto, no karaté, o peso também é considerado. Fomos verificar se existe associação entre a idade cronológica e os indicadores maturacionais e, encontrar modelos simples que permitam colocar em reflexão novas formas de avaliação da maturação. Foram recolhidos dados em 54 jovens praticantes de karaté (idade: 12,67 ± 2,49 anos; experiência: 4,99 ± 2,44 anos; altura: 150,45 ± 15,25cm; peso: 43,09 ± 14,17 kg, 20 raparigas). A idade correlacionou-se significativamente com auto-observação da maturação sexual (rho = 0,838; p < 0,01), e foi possível encontrar modelos de regressão simples que têm uma explicação moderada na maturação, apenas utilizando variáveis de medição simples, tal como a altura, o peso e o perímetro do braço. Estes resultados devem levar as entidades competentes a refletir acerca do modo de emparelhamento dos atletas nas competições de uma forma justa em termos de maturação.Paring children improve the chance for success and reduce injury in sport. Despite the maturity differences between children, chronological age remains the main criterion to equalize competition levels, but with limited efficiency. However, in Karate, weight is also considered. We went to investigate the association between chronological age and maturational indicators and find simple models to put on reflection new ways to assess the maturity. Data were collected in 54 young Karate practitioners (age: 12.67 ± 2.49 years, experience: 4.99 ± 2.44 years, height: 150.45 ± 15.25 cm, weight: 43.09 ± 14, 17 kg, 20 girls). Age correlated significantly with self-observation of sexual maturation (rho = 0.838; p < 0.01), and it was possible to find simple regression models that have a moderate explanation in maturation, using only simple measurable variables such as the height, weight and arm circumference. These results should lead the competent entities to reflect on the way of pairing of the athletes in the competitions, in a fair way in terms of maturation.info:eu-repo/semantics/publishedVersio

Melanosomes at a glance

Melanosomes, the pigment granules that provide tissues with colour and photoprotection, are the cellular site of synthesis, storage and transport of melanin pigments. They are synthesised in mammalian skin melanocytes, in choroidal melanocytes and retinal pigment epithelial (RPE) cells in the eye, and in melanophores (a class of pigment-containing cells) in lower vertebrates. The precise fate and functions of melanosomes vary according to cell type – epidermal melanocytes supply neighbouring keratinocytes with melanosomes, which results in the pigmentation of skin and hair, whereas pigment granules are retained intracellularly in RPE cells and choroidal melanocytes. In lower vertebrates, the reversible aggregation and dispersion of melanosomes throughout the melanophore enables rapid colour change and adaptation to the environment

Retinal progression biomarkers of early and intermediate age-related macular degeneration

Funding Information: Funding: This work was supported by Fundação para a Ciência e Tecnologia project PTDC/MED-PAT/30385/2017 and iNOVA4Health-UIDB/04462/2020, a program financially supported by Fun-dação para a Ciência e Tecnologia/Ministério da Educação e Ciência, Portugal, through national funds and co-funded by FEDER under the PT2020 Partnership Agreement. Funding Information: This work was supported by Fundação para a Ciência e Tecnologia project PTDC/MEDPAT/30385/2017 and iNOVA4Health-UIDB/04462/2020, a program financially supported by Fundação para a Ciência e Tecnologia/Ministério da Educação e Ciência, Portugal, through national funds and co-funded by FEDER under the PT2020 Partnership Agreement. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Early and intermediate AMD patients represent a heterogeneous population with an important but variable risk of progression to more advanced stages of the disease. The five-year progression from early and intermediate AMD to late disease is known to range from 0.4% to 53%. This wide variation explains the particular interest in searching predictive AMD biomarkers. Clinical parameters such as drusen size, presence of pigmentary abnormalities, and fellow eye status were, traditionally, the more important predictive elements. Multimodal retinal assessment (Color Fundus Photography, Optical Coherence Tomography, Optical Coherence Angiography and Fundus Autofluorescence) is providing new and accurate image biomarkers, useful in research and in daily practice. If individual progression risk could be anticipated, then management plans should be adapted accordingly, considering follow-up intervals and therapeutic interventions. Here, we reviewed the most important image progression biomarkers of early and intermediate AMD with relevant interest in clinical practice.publishersversionpublishe

Chromosomal mapping, gene structure and characterization of the human and murine RAB27B gene

BACKGROUND: Rab GTPases are regulators of intracellular membrane traffic. The Rab27 subfamily consists of Rab27a and Rab27b. Rab27a has been recently implicated in Griscelli Disease, a disease combining partial albinism with severe immunodeficiency. Rab27a plays a key role in the function of lysosomal-like organelles such as melanosomes in melanocytes and lytic granules in cytotoxic T lymphocytes. Little is known about Rab27b. RESULTS: The human RAB27B gene is organised in six exons, spanning about 69 kb in the chromosome 18q21.1 region. Exon 1 is non-coding and is separated from the others by 49 kb of DNA and exon 6 contains a long 3' untranslated sequence (6.4 kb). The mouse Rab27b cDNA shows 95% identity with the human cDNA at the protein level and maps to mouse chromosome 18. The mouse mRNA was detected in stomach, large intestine, spleen and eye by RT-PCR, and in heart, brain, spleen and kidney by Northern blot. Transient over-expression of EGF-Rab27b fusion protein in cultured melanocytes revealed that Rab27b is associated with melanosomes, as observed for EGF-Rab27a. CONCLUSIONS: Our results indicate that the Rab27 subfamily of Ras-like GTPases is highly conserved in mammals. There is high degree of conservation in sequence and gene structure between RAB27A and RAB27B genes. Exogenous expression of Rab27b in melanocytes results in melanosomal association as observed for Rab27a, suggesting the two Rab27 proteins are functional homologues. As with RAB27A in Griscelli Disease, RAB27B may be also associated with human disease mapping to chromosome 18