Near-equilibrium measurement of quantum size effects using Kelvin probe force microscopy

In nano-structures such as thin films electron confinement results in the quantization of energy levels in the direction perpendicular to the film. The discretization of the energy levels leads to the oscillatory dependence of many properties on the film thickness due to quantum size effects. Pb on Si(111) is a specially interesting system because a particular relationship between the Pb atomic layer thickness and its Fermi wavelength leads to a periodicity of the oscillation of two atomic layers. Here, we demonstrate how the combination of scanning force microscopy (SFM) and Kelvin probe force microscopy (KPFM) provides a reliable method to monitor the quantum oscillations in the work function of Pb ultra-thin film nano-structures on Si(111). Unlike other techniques, with SFM/KPFM we directly address single Pb islands, determine their height while suppressing the influence of electrostatic forces, and, in addition, simultaneously evaluate their local work function by measurements close to equilibrium, without current-dependent and non-equilibrium effects. Our results evidence even-odd oscillations in the work function as a function of the film thickness that decay linearly with the film thickness, proving that this method provides direct and precise information on the quantum states.Comment: This document is the unedited author's version of a Submitted Work that was subsequently accepted for publication in Nanoscale, copyright Royal Society of Chemistry after peer review. To access the final edited and published work see doi belo

Atomically resolved scanning force studies of vicinal Si(111)

Well-ordered stepped semiconductor surfaces attract intense attention owing to the regular arrangements of their atomic steps that makes them perfect templates for the growth of one- dimensional systems, e.g. nanowires. Here, we report on the atomic structure of the vicinal Si(111) surface with 10 degree miscut investigated by a joint frequency-modulation scanning force microscopy (FM-SFM) and ab initio approach. This popular stepped surface contains 7 x 7-reconstructed terraces oriented along the Si(111) direction, separated by a stepped region. Recently, the atomic structure of this triple step based on scanning tunneling microscopy (STM) images has been subject of debate. Unlike STM, SFM atomic resolution capability arises from chemical bonding of the tip apex with the surface atoms. Thus, for surfaces with a corrugated density of states such as semiconductors, SFM provides complementary information to STM and partially removes the dependency of the topography on the electronic structure. Our FM-SFM images with unprecedented spatial resolution on steps confirm the model based on a (7 7 10) orientation of the surface and reveal structural details of this surface. Two different FM-SFM contrasts together with density functional theory calculations explain the presence of defects, buckling and filling asymmetries on the surface. Our results evidence the important role of charge transfers between adatoms, restatoms, and dimers in the stabilisation of the structure of the vicinal surface

El juego de chuncana entre los chimú. Un tablero de madera que prueba la hipótesis de Erland Nordenskiöld

A principios del siglo XX el antropólogo sueco Nordenskiöld describe un tipo de juego que los indígenas del Chaco practican al final de la época de lluvias, en el mes de marzo. Nordenskiöld plantea la hipótesis de que tal juego es de origen andino. Añadiendo nuevas pruebas lingüísticas y etnológicas, así como la aplicabilidad de las reglas del referido juego del Chaco, la autora trata de demostrar, basándose en un estudio iconográfico, que un tablero de juego de la época chimú que se encuentra en el Museo Linden, Alemania, podría probar la hipótesis de Nordenskiöld.Au début du 20ème siècle l’anthropologue suédois Erland Nordenskiöld décrivit une forme de jeu pratiqué par les indigènes de la région de Chaco à la fin de la saison des pluies au mois de mars. Nordenskiöld soutient l’hypothèse que ce jeu pourrait avoir ses origines dans les Andes. L’auteur établit la probabilité de cette hypothèse en se basant sur l’analyse iconographique d’une planche en bois d’un jeu de l’époque Chimú, planche qui appartient à la collection du Musée Linden en Allemagne. L’auteur apporte des arguments linguistiques et éthnologiques supplémentaires, comme une description des règles du jeu, ce qui appuie l’hypothèse de Nordenskiöld.In the beginning of the 20th century, the Swedish anthropologist Erland Nordenskiöld described a game played by the indigenous people of the Chaco Region at the end of the rainy season (March). Nordenskiöld asserts as a hypothesis that game might have its origins in the Andes. The authors proves that hypothesis correct using an iconografic analysis of a wooden game board of the Chimu culture that is in the collection of the Linden Museum in Germany. The author presents additional linguistic and ethnological arguments as well as a game description that supports Nordenkiöld hypothesis

Abortamento/aborto: representações sociais de enfermeiras da atenção básica à saúde

Disertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciencias da Saude, Programa de Pós-Graduação em Enfermagem, Florianópolis, 2010O abortamento/aborto é uma realidade presente em nossa sociedade. É um tema polêmico, que traz múltiplas interpretações e representa interesses diversos às instituições sociais, sendo um problema de saúde pública e um desafio para os profissionais da saúde. A Atenção Básica à Saúde, porta de entrada dos usuários no Sistema Único de Saúde - SUS, recebe, algumas vezes, mulheres com a intenção de praticar o aborto e, nessa situação, as enfermeiras devido à complexidade da temática, encontram dificuldades na prática do cuidado. O estudo teve como objetivo conhecer como as enfermeiras que atuam na Atenção Básica à Saúde no município de Chapecó/SC, representam o abortamento/aborto inseguro e como essas representações podem se relacionar com as formas de se prestar cuidados em situações concretas. Trata-se de uma pesquisa de abordagem qualitativa, tipo exploratório descritivo, fundamentada na Teoria das Representações Sociais. Os dados foram coletados no período de julho a setembro de 2009, por meio da técnica de "Grupo Focal", constituído por oito enfermeiras que atuam na Atenção Básica à Saúde. A análise dos dados utilizou o método do Discurso do Sujeito Coletivo. Os discursos dão conta de que, nessas situações, a prática do cuidado vem permeada de conflitos entre posicionar-se contra o aborto ou apoiar às mulheres, e ou, manter-se na imparcialidade, deixando a responsabilidade de decisão e ação para elas. Algumas das representações tais como: 'o aborto inseguro ser um crime; o dever da mulher ficar com a criança ou entregá-la para adoção; a preservação da vida como princípio a ser almejado pela formação profissional...' normalmente desencadeiam tentativas de influenciar a mulher a não interromper a gravidez. Quando não obtém sucesso nessas tentativas, algumas enfermeiras mesmo desejando ajudar a mulher a encontrar uma saída segura, pelos limites profissionais, apenas a orientam a 'ir pra casa pensar, deixando claro que não é com ela (a enfermeira) a prática do aborto. Ficando a mulher abandonada..., indo pra clandestinidade..., tendo que se virar.' Outros discursos, trazem claramente o poder do Estado sobre as representações: 'se ocorrer o aborto pelo uso da pílula do dia seguinte ou do DIU de cobre, por serem métodos permitidos pelo governo e pela sociedade, seria considerado aborto legal e, também aborto permitido por Deus'. As enfermeiras participantes da pesquisa, nos debates dos grupos focais, refletiram a respeito de seus posicionamentos profissionais, ancorados por concepções religiosas, familiares e da formação, questionando-se: 'que 'vida' preservar? Se a criança que não é abortada, pode ser 'abortada em vida, a criança vivendo na miséria' e a mãe o 'inferno''. Essas reflexões levaram as enfermeiras a concluírem que, o posicionamento imparcial, as libera de futuras responsabilidades para com as 'crianças que não foram abortadas e vivem na condição de mortas vivas'.Abortion is a reality in our society, is a controversial issue that brings many different interpretations representing diverse interests and social institutions. The public health problem and a challenge for health professionals. The primary health gateway for users in the Unified Health System - SUS, receive, sometimes, women with the intention of abortion and, in this situation, the nurses, because of the complexity of the subject, find it difficult to explain the issues with the matter. The study aims to understand how nurses working in primary health in Chapecó / SC represent the abortion / unsafe abortion and how these representations may be related to the ways of providing care in specific situations. This is a qualitative approach, an exploratory and descriptive type, based on the Theory of Social Representations. Data were collected from July to September 2009, using the technique of "Focus Group", consisting of eight nurses working in primary health. The data analysis used the method of the Collective Subject Discourse. Speeches show that in those situations, the practice of care are permeated with conflicting stances against abortion and support to pregnant women and / or maintain the impartiality, leaving the responsibility of decision and action to them. Some of the representations such as 'unsafe abortion is a crime, the duty of the woman to keep the child or give it for adoption, the preservation of life, as a principle to be chosen in the professional training,' usually trigger attempts of women to stop pregnancy. When there is no success in these attempts, some nurses are even willing to help the woman find a safe way out, by professional boundaries, by guiding them to 'go home and think about it, making it clear that is not her (the nurse) to practice abortion. And making them understand that the procedure will be done illegally , that the woman may be abandoned .Other speeches bring clearly state power on the representation:' if abortion occurs by the use of morning-after pill or IUD Copper, being the methods permitted by the government and society, it would also be considered legal abortion and abortion also permitted by God. The nurses participating in the research, in discussions of the focus groups reflected the respect of their professional positions, anchored in religious views, family and training, questioning, 'which life 'preserve? If the child is not aborted, can be 'aborted alive, children would be living in poverty' and mother in 'hell''. These considerations led the nurses to conclude that the neutral position is the best one. Because it releases them of future liabilities to the 'children who were not aborted and will be living in conditions of living dead'

Altered Metabolic Phenotype of Immune Cells in a Spontaneous Autoimmune Uveitis Model

As one of the leading causes of blindness worldwide, uveitis is an important disease. The exact pathogenesis of autoimmune uveitis is not entirely elucidated to date. Equine recurrent uveitis (ERU) represents the only spontaneous animal model for autoimmune uveitis in humans. As the metabolism of immune cells is an emerging field in research and gains more and more significance to take part in the pathogenesis of various diseases, we conducted experiments to investigate the metabolism of immune cells of ERU cases and healthy controls. To our knowledge, the link between a deviant immunometabolism and the pathogenesis of autoimmune uveitis was not investigated so far. We showed that PBMC of ERU cases had a more active metabolic phenotype in basal state by upregulating both the oxidative phosphorylation and the glycolytic pathway. We further revealed an increased compensatory glycolytic rate of PBMC and CD4(+) T cells of ERU cases under mitochondrial stress conditions. These findings are in line with metabolic alterations of immune cells in other autoimmune diseases and basic research, where it was shown that activated immune cells have an increased need of energy and molecule demand for their effector function. We demonstrated a clear difference in the metabolic phenotypes of PBMC and, more specifically, CD4(+) T cells of ERU cases and controls. These findings are another important step in understanding the pathogenesis of ERU and figuratively, human autoimmune uveitis

Myocardial Ischemia and Reperfusion Leads to Transient CD8 Immune Deficiency and Accelerated Immunosenescence in CMV-Seropositive Patients

Rationale: There is mounting evidence of a higher incidence of coronary heart disease (CHD) in cytomegalovirus (CMV) seropositive individuals. Objective: The aim of this study was to investigate whether acute MI triggers an inflammatory T-cell response that might lead to accelerated immunosenescence in CMV-seropositive patients. Methods and Results: Thirty-four patients with acute MI undergoing primary PCI (PPCI) were longitudinally studied within 3 months following reperfusion (Cohort A). In addition, 54 patients with acute and chronic MI were analyzed in a cross-sectional study (Cohort B). CMV-seropositive patients demonstrated a greater fall in the concentration of terminally differentiated CD8 effector memory T cells (TEMRA) in peripheral blood during the first 30 min of reperfusion compared with CMV-seronegative patients (-192 vs. -63 cells/µl; p=0.008), correlating with the expression of programmed cell death-1 (PD-1) before PPCI (r=0.8; p=0.0002). A significant proportion of TEMRA cells remained depleted for at least 3 months in CMV-seropositive patients. Using high-throughput 13-parameter flow cytometry and HLA class I CMV-specific dextramers, we confirmed an acute and persistent depletion of terminally differentiated TEMRA and CMV-specific CD8+ cells in CMV-seropositive patients. Long-term reconstitution of the TEMRA pool in chronic CMV-seropositive post-MI patients was associated with signs of terminal differentiation including an increase in KLRG1 and shorter telomere length in CD8+ T cells (2225 bp vs. 3397 bp; p<0.001). Conclusions: Myocardial ischemia and reperfusion in CMV-seropositive patients undergoing PPCI leads to acute loss of antigen-specific, terminally differentiated CD8 T-cells, possibly through PD-1-dependent programmed cell death. Our results suggest that acute MI and reperfusion accelerate immunosenescence in CMV-seropositive patients

SARS-CoV-2, a Threat to Privacy?

The global SARS-CoV-2 pandemic is currently putting a massive strain on the world's critical infrastructures. With healthcare systems and internet service providers already struggling to provide reliable service, some operators may, intentionally or unintentionally, lever out privacy-protecting measures to increase their system's efficiency in fighting the virus. Moreover, though it may seem all encouraging to see the effectiveness of authoritarian states in battling the crisis, we, the authors of this paper, would like to raise the community's awareness towards developing more effective means in battling the crisis without the need to limit fundamental human rights. To analyze the current situation, we are discussing and evaluating the steps corporations and governments are taking to condemn the virus by applying established privacy research

In utero ultrafine particulate matter exposure causes offspring pulmonary immunosuppression.

Early life exposure to fine particulate matter (PM) in air is associated with infant respiratory disease and childhood asthma, but limited epidemiological data exist concerning the impacts of ultrafine particles (UFPs) on the etiology of childhood respiratory disease. Specifically, the role of UFPs in amplifying Th2- and/or Th17-driven inflammation (asthma promotion) or suppressing effector T cells (increased susceptibility to respiratory infection) remains unclear. Using a mouse model of in utero UFP exposure, we determined early immunological responses to house dust mite (HDM) allergen in offspring challenged from 0 to 4 wk of age. Two mice strains were exposed throughout gestation: C57BL/6 (sensitive to oxidative stress) and BALB/C (sensitive to allergen exposure). Offspring exposed to UFPs in utero exhibited reduced inflammatory response to HDM. Compared with filtered air (FA)-exposed/HDM-challenged mice, UFP-exposed offspring had lower white blood cell counts in bronchoalveolar lavage fluid and less pronounced peribronchiolar inflammation in both strains, albeit more apparent in C57BL/6 mice. In the C57BL/6 strain, offspring exposed in utero to FA and challenged with HDM exhibited a robust response in inflammatory cytokines IL-13 and Il-17. In contrast, this response was lost in offspring exposed in utero to UFPs. Circulating IL-10 was significantly up-regulated in C57BL/6 offspring exposed to UFPs, suggesting increased regulatory T cell expression and suppressed Th2/Th17 response. Our results reveal that in utero UFP exposure at a level close to the WHO recommended PM guideline suppresses an early immune response to HDM allergen, likely predisposing neonates to respiratory infection and altering long-term pulmonary health