The Husain-Kuchar Model: Time Variables and Non-degenerate Metrics

We study the Husain-Kuchar model by introducing a new action principle similar to the self-dual action used in the Ashtekar variables approach to Quantum Gravity. This new action has several interesting features; among them, the presence of a scalar time variable that allows the definition of geometric observables without adding new degrees of freedom, the appearance of a natural non-degenerate four-metric and the possibility of coupling ordinary matter.Comment: LaTeX, 22 pages, accepted for publication in Phys. Rev.

Pancreas divisum. Correlation between anatomical abnormalities and bile precipitation in the gallbladder in seven patients

Pancreas divisum is a genetic defect associated with recurrent acute pancreatitis due to insufficient drainage of the accessory pancreatic duct. Seven young patients diagnosed with pancreatic divisum and thickening of the gallbladder bile as shown on magnetic resonance cholangio-pancreatography without pancreatic ductal changes underwent laparoscopic cholecystectomy. During the mean follow-up of 32 months no episode of pancreatitis was reported. There is an association between PD and higher concentration of bile in the gallbladder. Cholecystectomy can be considered curative in patients with PD in the absence of indications for major surgery

The effects of anthocyanin-rich Myrtaceae fruits peel powder on fibrosis-associated hepatocarcinogenesisin mice.

Fruits from Myrtaceae family, as jabuticaba (Myrciaria jaboticaba (Vell) O. Berg), jamelão (Syzygium cumini (L.) Skeels) and jambo (Syzygium malaccense), raise interest due to their high levels of anthocyanins, antioxidant compounds, and, thus, potential for chronic disease risk reduction¹. Therefore, the study evaluated whether the ingestion of jabuticaba, jamelão or jambo peel powder attenuates fibrosis-associated hepatocarcinogenesis. Neonatal female C3H/Hej mice were submitted to a diethylnitrosamine (DEN)/carbon tetrachloride (CCl4)-induced fibrosis-associated hepatocarcinogenesis model. Mice also received basal diet or basal diet containing 2% of jabuticaba, jamelão or jambo dehydrated peels for 10 weeks. HPLC analysis of dehydrated fruit peels revealed high levels of anthocyanins in jabuticaba (802.89±22.88 mg/100g), jamelão (575.95±9.42 mg/100g) and jambo (156.05±10.39 mg/100g). These fruits displayed different types of anthocyanins (Figures 1-3). Interestingly, only the ingestion of basal diet containing jamelão peel powder attenuated liver fibrosis compared to DEN/CCl4 (Figure 4). Mechanisms will be evaluated, as well as the effects of these fruits on the development of preneoplasic/neoplastic liver lesions.WTPC. 21 a 26 de abril

Epidemic dynamics in finite size scale-free networks

Many real networks present a bounded scale-free behavior with a connectivity cut-off due to physical constraints or a finite network size. We study epidemic dynamics in bounded scale-free networks with soft and hard connectivity cut-offs. The finite size effects introduced by the cut-off induce an epidemic threshold that approaches zero at increasing sizes. The induced epidemic threshold is very small even at a relatively small cut-off, showing that the neglection of connectivity fluctuations in bounded scale-free networks leads to a strong over-estimation of the epidemic threshold. We provide the expression for the infection prevalence and discuss its finite size corrections. The present work shows that the highly heterogeneous nature of scale-free networks does not allow the use of homogeneous approximations even for systems of a relatively small number of nodes.Comment: 4 pages, 2 eps figure

Towards complete integrability of two dimensional Poincar\'e gauge gravity

It is shown that gravity on the line can be described by the two dimensional (2D) Hilbert-Einstein Lagrangian supplemented by a kinetic term for the coframe and a translational {\it boundary} term. The resulting model is equivalent to a Yang-Mills theory of local {\it translations} and frozen Lorentz gauge degrees. We will show that this restricted Poincar\'e gauge model in 2 dimensions is completely integrable. {\it Exact} wave, charged black hole, and `dilaton' solutions are then readily found. In vacuum, the integrability of the {\it general} 2D Poincar\'e gauge theory is formally proved along the same line of reasoning.Comment: 35 pages, report Cologne-thp-1993-H

Class of correlated random networks with hidden variables

We study a class models of correlated random networks in which vertices are characterized by \textit{hidden variables} controlling the establishment of edges between pairs of vertices. We find analytical expressions for the main topological properties of these models as a function of the distribution of hidden variables and the probability of connecting vertices. The expressions obtained are checked by means of numerical simulations in a particular example. The general model is extended to describe a practical algorithm to generate random networks with an \textit{a priori} specified correlation structure. We also present an extension of the class, to map non-equilibrium growing networks to networks with hidden variables that represent the time at which each vertex was introduced in the system

Epidemic processes in complex networks

In recent years the research community has accumulated overwhelming evidence for the emergence of complex and heterogeneous connectivity patterns in a wide range of biological and sociotechnical systems. The complex properties of real-world networks have a profound impact on the behavior of equilibrium and nonequilibrium phenomena occurring in various systems, and the study of epidemic spreading is central to our understanding of the unfolding of dynamical processes in complex networks. The theoretical analysis of epidemic spreading in heterogeneous networks requires the development of novel analytical frameworks, and it has produced results of conceptual and practical relevance. A coherent and comprehensive review of the vast research activity concerning epidemic processes is presented, detailing the successful theoretical approaches as well as making their limits and assumptions clear. Physicists, mathematicians, epidemiologists, computer, and social scientists share a common interest in studying epidemic spreading and rely on similar models for the description of the diffusion of pathogens, knowledge, and innovation. For this reason, while focusing on the main results and the paradigmatic models in infectious disease modeling, the major results concerning generalized social contagion processes are also presented. Finally, the research activity at the forefront in the study of epidemic spreading in coevolving, coupled, and time-varying networks is reported.Comment: 62 pages, 15 figures, final versio

Use of artificial vision techniques for diagnostic of nitrogen nutritional status in maize plants

The identification of the nutritional status of maize by foliar chemical analysis requires sampling of leaves when the plant is in an advanced stage of development, hindering corrective action in ongoing cultivation, if deficiency detection of a specific nutrient occurs. An artificial vision system (AVS) is a set of methods used for analysis and interpretation of images. Therefore, an AVS is being developed to identify nutrient deficiencies at different stages of plant development, especially in the early stages of growth, which may contribute to early diagnosis and correction in the same cycle of growth. The objective was to evaluate methods of digital image processing to develop the AVS to diagnose induced nitrogen deficiency in maize leaves. The experiment was done in greenhouse and the treatments were N doses (0.0; 3.0; 6.0 e 15.0 mMol L-1) combined with three growing stages (V4, V7 and R1). The images of maize leaves were digitized in 1200 dpi. After scanning, leaves were chemically analyzed for N content and was determined the dry mass of plants. The studied methods in AVS were: Volumetric Fractal Dimension (VFD), Gabor Wavelet (GW) and VFD with canonical analysis. The omission and reduction of nitrogen in maize plants resulted in typical symptoms of N deficiency. The AVS was able to identify levels of nitrogen deficiency in the early stages of development of corn, with global percentage of right of 82.5% at V4 and 87.5% at V7. The GW technique with color images resulted in the better method for features extraction.FAPESP (10/18233-3; 09/51835-0

Identification of COVID-19 patients at risk of hospital admission and mortality: a European multicentre retrospective analysis of mid-regional pro-adrenomedullin

Background: Mid-Regional pro-Adrenomedullin (MR-proADM) is an inflammatory biomarker that improves the prognostic assessment of patients with sepsis, septic shock and organ failure. Previous studies of MR-proADM have primarily focussed on bacterial infections. A limited number of small and monocentric studies have examined MR-proADM as a prognostic factor in patients infected with SARS-CoV-2, however there is need for multicenter validation. An evaluation of its utility in predicting need for hospitalisation in viral infections was also performed. Methods: An observational retrospective analysis of 1861 patients, with SARS-CoV-2 confirmed by RT-qPCR, from 10 hospitals across Europe was performed. Biomarkers, taken upon presentation to Emergency Departments (ED), clinical scores, patient demographics and outcomes were collected. Multiclass random forest classifier models were generated as well as calculation of area under the curve analysis. The primary endpoint was hospital admission with and without death. Results: Patients suitable for safe discharge from Emergency Departments could be identified through an MR-proADM value of ≤ 1.02 nmol/L in combination with a CRP (C-Reactive Protein) of ≤ 20.2 mg/L and age ≤ 64, or in combination with a SOFA (Sequential Organ Failure Assessment) score < 2 if MR-proADM was ≤ 0.83 nmol/L regardless of age. Those at an increased risk of mortality could be identified upon presentation to secondary care with an MR-proADM value of > 0.85 nmol/L, in combination with a SOFA score ≥ 2 and LDH > 720 U/L, or in combination with a CRP > 29.26 mg/L and age ≤ 64, when MR-proADM was > 1.02 nmol/L. Conclusions: This international study suggests that for patients presenting to the ED with confirmed SARS-CoV-2 infection, MR-proADM in combination with age and CRP or with the patient’s SOFA score could identify patients at low risk where outpatient treatment may be safe