Quantum Criticality and Superconductivity in Quasi-Two-Dimensional Dirac Electronic Systems

We present a theory describing the superconducting (SC) interaction of Dirac electrons in a quasi-two-dimensional system consisting of a stack of N planes. The occurrence of a SC phase is investigated both at T=0 and T\neq 0, in the case of a local interaction, when the theory must be renormalized and also in the situation where a natural physical cutoff is present in the system. In both cases, at T=0, we find a quantum phase transition connecting the normal and SC phases at a certain critical coupling. The phase structure is shown to be robust against quantum fluctuations. The SC gap is determined for T=0 and T\neq 0, both with and without a physical cutoff and the interplay between the gap and the SC order parameter is discussed. Our theory qualitatively reproduces the SC phase transition occurring in the underdoped regime of the high-Tc cuprates. This fact points to the possible relevance of Dirac electrons in the mechanism of high-Tc superconductivity.Comment: To be published in Nuclear Physics, Section B. 24 pages, 4 figure

Controle da hipertensão arterial: desafio na Atenção Primaria à Saúde

A hipertensão arterial sistêmica (HAS) é uma patologia que atinge cerca de 30% da população adulta e constitui um dos principais fatores de risco para o padecimento de doenças cardiovasculares. O controle da HAS está diretamente relacionado ao grau de adesão do paciente ao regime terapêuticoe mudanças do estilo de vida. Na prática diária encontramos inadequado acompanhamento e controle da doençasituando aos pacientes em risco. Este estudo tem como objetivo propor um plano de intervenção para adequado acompanhamento, estimulando mudanças nos estilos de vida e melhor adesão ao tratamento anti-hipertensivo para os indivíduos portadores de HAS e residentes na área de abrangência do CMS Morro União situada na zona norte da cidade do Rio de Janeiro. Será realizado um estudo com avaliação mensal dos hipertensos acompanhados e cadastrados nesse CMS.Este estudo pretende contribuir para a melhor avaliação e acompanhamento dos pacientes portadores de hipertensão arterial, incentivando a adoção de estratégias de promoção, prevenção e controle, para minimizar ou evitar complicações decorrentes da hipertensão arterial sistêmica

Against mass media trends: Minority growth in cultural globalization

We investigate the collective behavior of a globalized society under the influence of endogenous mass media trends. The mass media trend is a global field corresponding to the statistical mode of the states of the agents in the system. The interaction dynamics is based on Axelrod’s rules for the dissemination of culture. We find situations where the largest minority group, possessing a cultural state different from that of the predominant trend transmitted by the mass media, can grow to almost half of the size of the population. We show that this phenomenon occurs when a critical number of long-range connections are present in the underlying network of interactions. We have numerically characterized four phases on the space of parameters of the system: an ordered phase; a semi-ordered phase where almost half of the population consists of the largest minority in a state different from that of the mass media; a disordered phase; and a chimera-like phase where one large domain coexists with many very small domains

Isotopic labelling reveals the efficient adaptation of wheat root TCA cycle flux modes to match carbon demand under ammonium nutrition

Proper carbon (C) supply is essential for nitrogen (N) assimilation especially when plants are grown under ammonium (NH4+) nutrition. However, how C and N metabolic fluxes adapt to achieve so remains uncertain. In this work, roots of wheat (Triticum aestivum L.) plants grown under exclusive NH4+ or nitrate (NO3−) supply were incubated with isotope-labelled substrates (15NH4+, 15NO3−, or [13C]Pyruvate) to follow the incorporation of 15N or 13C into amino acids and organic acids. Roots of plants adapted to ammonium nutrition presented higher capacity to incorporate both 15NH4+ and 15NO3− into amino acids, thanks to the previous induction of the NH4+ assimilative machinery. The 15N label was firstly incorporated into [15N]Gln vía glutamine synthetase; ultimately leading to [15N]Asn accumulation as an optimal NH4+ storage. The provision of [13C]Pyruvate led to [13C]Citrate and [13C]Malate accumulation and to rapid [13C]2-OG consumption for amino acid synthesis and highlighted the importance of the anaplerotic routes associated to tricarboxylic acid (TCA) cycle. Taken together, our results indicate that root adaptation to ammonium nutrition allowed efficient assimilation of N thanks to the promotion of TCA cycle open flux modes in order to sustain C skeleton availability for effective NH4+ detoxification into amino acids

C and N abundances of MS and SGB stars in NGC 1851

We present the first chemical analysis of stars on the double subgiant branch (SGB) of the globular cluster NGC 1851. We obtained 48 Magellan IMACS spectra of subgiants and fainter stars covering the spectral region between 3650-6750\AA, to derive C and N abundances from the spectral features at 4300\AA (G-band) and at ~ 3883\AA (CN). We added to our sample ~ 45 unvevolved stars previously observed with FORS2 at the VLT. These two datasets were homogeneously reduced and analyzed. We derived abundances of C and N for a total of 64 stars and found considerable star-to-star variations in both [C/H] and [N/H] at all luminosities extending to the red giant branch (RGB) base (V~18.9). These abundances appear to be strongly anticorrelated, as would be expected from the CN-cycle enrichment, but we did not detect any bimodality in the C or N content. We used HST and ground-based photometry to select two groups of faint- and bright-SGB stars from the visual and Str\"omgren color-magnitude diagrams. Significant variations in the carbon and nitrogen abundances are present among stars of each group, which indicates that each SGB hosts multiple subgenerations of stars. Bright- and faint-SGB stars differ in the total C+N content, where the fainter SGB have about 2.5 times the C+N content of the brighter ones. Coupling our results with literature photometric data and abundance determinations from high-resolution studies, we identify the fainter SGB with the red-RGB population, which also should be richer on average in Ba and other s-process elements, as well as in Na and N, when compared to brighter SGB and the blue-RGB population.Comment: 17 pages, 3 tables, 16 figures; typos corrected, added checks on temperature scale; A&A accepted (in press

Dogs attending primary-care practice in England with clinical signs suggestive of Chiari-like malformation/syringomyelia

Chiari-like malformation/syringomyelia (CM/SM) in dogs describes a developmental disorder that can cause pain and reduced quality of life. This retrospective study aimed to report the period prevalence, clinical signs and risk factors for diagnosis of symptomatic CM/SM in the veterinary primary-care setting using a cross-sectional design. The study population included all dogs within the VetCompass Programme (September 1, 2009–June 13, 2014). Overall, the period prevalence of symptomatic CM/SM was 0.05 per cent (95 per cent CI 0.04 per cent to 0.06 per cent) for all breeds. The period prevalence in the Cavalier King Charles Spaniel (CKCS) was 1.6 per cent (95 per cent CI 1.2 to 2.06). Other breeds at increased odds included the King Charles Spaniel (KCS), Affenpinscher, Chihuahua and Pomeranian. Insured dogs had 4.6 times the odds (95 per cent CI 2.95 to 7.17) of having a diagnosis of CM/SM compared with uninsured dogs. Pain was the most commonly associated clinical sign (67 dogs, 72 per cent). Analgesics were prescribed to 72 (77.4 per cent) of the symptomatic dogs. Despite its low overall period prevalence, the high proportion of affected dogs identified with chronic pain suggests a significant welfare issue. Financial implications could impede the diagnostic process and lead to underestimation of the true prevalence. This study may help to inform clinicians about the clinical relevance and the need for improved awareness of clinical signs, particularly in high-risk breeds, to optimise the management of CM/SM in primary-care practice

Primordial r-process Dispersion in Metal-Poor Globular Clusters

Heavy elements, those produced by neutron-capture reactions, have traditionally shown no star-to-star dispersion in all but a handful of metal-poor globular clusters (GCs). Recent detections of low [Pb/Eu] ratios or upper limits in several metal-poor GCs indicate that the heavy elements in these GCs were produced exclusively by an r-process. Reexamining GC heavy element abundances from the literature, we find unmistakable correlations between the [La/Fe] and [Eu/Fe] ratios in 4 metal-poor GCs (M5, M15, M92, and NGC 3201), only 2 of which were known previously. This indicates that the total r-process abundances vary star-to-star (by factors of 2-6) relative to Fe within each GC. We also identify potential dispersion in two other GCs (M3 and M13). Several GCs (M12, M80, and NGC 6752) show no evidence of r-process dispersion. The r-process dispersion is not correlated with the well-known light element dispersion, indicating it was present in the gas throughout the duration of star formation. The observations available at present suggest that star-to-star r-process dispersion within metal-poor GCs may be a common but not ubiquitous phenomenon that is neither predicted by nor accounted for in current models of GC formation and evolution.Comment: Accepted for publication in the Astrophysical Journal Letters (6 pages, 2 figures). v2: references update

Syringomyelia and Craniocervical Junction Abnormalities in Chihuahuas

Background: Chiari-like malformation (CM) and syringomyelia (SM) are widely reported in Cavalier King Charles Spaniels and Griffon Bruxellois dogs. Increasing evidence indicates that CM and SM also occur in other small and toy breed dogs, such as Chihuahuas. Objectives: To describe the presence of SM and craniocervical junction (CCJ) abnormalities in Chihuahuas and to evaluate the possible association of CCJ abnormalities with SM. To describe CM/SM-related clinical signs and neurologic deficits and to investigate the association of CM/SM-related clinical signs with signalment, SM, or CCJ abnormalities. Animals: Fifty-three client-owned Chihuahuas. Methods: Prospective study. Questionnaire analyses and physical and neurologic examinations were obtained before magnetic resonance and computed tomography imaging. Images were evaluated for the presence of SM, CM, and atlantooccipital overlapping. Additionally, medullary kinking, dorsal spinal cord compression, and their sum indices were calculated. Results: Scratching was the most common CM/SM-related clinical sign and decreased postural reaction the most common neurologic deficit in 73 and 87% of dogs, respectively. Chiari-like malformation and SM were present in 100 and 38% of dogs, respectively. Syringomyelia was associated with the presence of CM/SM-related clinical signs (P = 0.034), and medullary kinking and sum indices were higher in dogs with clinical signs (P = 0.016 and P = 0.007, respectively). Conclusions and Clinical Importance: Syringomyelia and CCJ abnormalities are prevalent in Chihuahuas. Syringomyelia was an important factor for the presence of CM/SM-related clinical signs, but many dogs suffered from similar clinical signs without being affected by SM, highlighting the clinical importance of CCJ abnormalities in Chihuahuas.Peer reviewe

Detecting aquaculture platforms using COSMO SkyMed

Aquaculture are a very valuable asset for many coastal countries and in the future they will play an important role in food security. Satellite remote sensing can improve the temporal and geo-spatial analysis of such marine facilities. Detecting platforms used for fish and shellfish farming provides a way to monitor assets and check they do not get damaged by storms. It also allows to identify illegal placement of structures in areas which should not host farms. In this work, we want to evaluate the use of COMSO SkyMed polarimetric acquisitions. In particular, we want to use a novel methodology called intensity Dual-Pol Ratio Anomaly Detector (iDPolRAD). Extensive work has been carried out on detecting ships using space-borne Synthetic Aperture Radar (SAR) systems. However, the identification of smaller and non-metallic targets is still challenging especially when the sea conditions are rough. This work presents an assessment of different detectors and polarimetric information for the detection of wooden mussels platforms. The results show that the use of dual polarimetric information can improve the detection performance. © VDE VERLAG GMBH Berlin Offenbac

On the Dynamics of Comets in Extrasolar Planetary Systems

Since very recently, we acquired knowledge on the existence of comets in extrasolar planetary systems. The formation of comets together with planets around host stars now seems evident. As stars are often born in clusters of interstellar clouds, the interaction between the systems will lead to the exchange of material at the edge of the clouds. Therefore, almost every planetary system should have leftover remnants as a result of planetary formation in form of comets at the edges of those systems. These Oort clouds around stars are often disturbed by different processes (e.g., galactic tides, passing stars, etc.), which consequently scatter bodies from the distant clouds into the system close to the host star. Regarding the Solar System, we observe this outcome in the form of cometary families. This knowledge supports the assumption of the existence of comets around other stars. In the present work, we study the orbital dynamics of hypothetical exocomets, based on detailed computer simulations, in three star-planet systems, which are: HD~10180, 47~UMa, and HD~141399. These systems host one or more Jupiter-like planets, which change the orbits of the incoming comets in characteristic ways