Nonmonotonic Magnetic Susceptibility of Dipolar Hard-Spheres at Low Temperature and Density

We investigate, via numerical simulations, mean field, and density functional theories, the magnetic response of a dipolar hard sphere fluid at low temperatures and densities, in the region of strong association. The proposed parameter-free theory is able to capture both the density and temperature dependence of the ring-chain equilibrium and the contribution to the susceptibility of a chain of generic length. The theory predicts a nonmonotonic temperature dependence of the initial (zero field) magnetic susceptibility, arising from the competition between magnetically inert particle rings and magnetically active chains. Monte Carlo simulation results closely agree with the theoretical findings. DOI: 10.1103/PhysRevLett.110.148306

Computing the phase diagram of binary mixtures: A patchy particle case study

We investigate the phase behaviour of 2D mixtures of bi-functional and three-functional patchy particles and 3D mixtures of bi-functional and tetra-functional patchy particles by means of Monte Carlo simulations and Wertheim theory. We start by computing the critical points of the pure systems and then we investigate how the critical parameters change upon lowering the temperature. We extend the successive umbrella sampling method to mixtures to make it possible to extract information about the phase behaviour of the system at a fixed temperature for the whole range of densities and compositions of interest. (C) 2013 AIP Publishing LLC.

Branching points in the low-temperature dipolar hard sphere fluid

In this contribution, we investigate the low-temperature, low-density behaviour of dipolar hard-sphere (DHS) particles, i.e., hard spheres with dipoles embedded in their centre. We aim at describing the DHS fluid in terms of a network of chains and rings (the fundamental clusters) held together by branching points (defects) of different nature. We first introduce a systematic way of classifying inter-cluster connections according to their topology, and then employ this classification to analyse the geometric and thermodynamic properties of each class of defects, as extracted from state-of-the-art equilibrium Monte Carlo simulations. By computing the average density and energetic cost of each defect class, we find that the relevant contribution to inter-cluster interactions is indeed provided by (rare) three-way junctions and by four-way junctions arising from parallel or anti-parallel locally linear aggregates. All other (numerous) defects are either intra-cluster or associated to low cluster-cluster interaction energies, suggesting that these defects do not play a significant part in the thermodynamic description of the self-assembly processes of dipolar hard spheres. (C) 2013 AIP Publishing LLC.

Nonlinear mixture model for hyperspectral unmixing

Proceedings of International Conference - SPIE 7477, Image and Signal Processing for Remote Sensing XV - 28 September 2009

Self-assembly in chains, rings, and branches: a single component system with two critical points

Agências financiadoras: FCT - PEstOE/FIS/UI0618/2011; PTDC/FIS/098254/2008 ERC-PATCHYCOLLOIDS e MIUR-PRIN

Recent history of fractional calculus

This survey intends to report some of the major documents and events in the area of fractional calculus that took place since 1974 up to the present date.

Properties of patchy colloidal particles close to a surface: a Monte Carlo and density functional study

We investigate the behavior of a patchy particle model close to a hard-wall via Monte Carlo simulation and density functional theory (DFT). Two DFT approaches, based on the homogeneous and inhomogeneous versions of Wertheim's first order perturbation theory for the association free energy are used. We evaluate, by simulation and theory, the equilibrium bulk phase diagram of the fluid and analyze the surface properties for two isochores, one of which is close to the liquid side of the gas-liquid coexistence curve. We find that the density profile near the wall crosses over from a typical high-temperature adsorption profile to a low-temperature desorption one, for the isochore close to coexistence. We relate this behavior to the properties of the bulk network liquid and find that the theoretical descriptions are reasonably accurate in this regime. At very low temperatures, however, an almost fully bonded network is formed, and the simulations reveal a second adsorption regime which is not captured by DFT. We trace this failure to the neglect of orientational correlations of the particles, which are found to exhibit surface induced orientational order in this regime.

Quantitative description of the self-assembly of patchy particles into chains and rings

We numerically study a simple fluid composed of particles having a hard-core repulsion complemented by two patchy attractive sites on the particle poles. An appropriate choice of the patch angular width allows for the formation of ring structures which, at low temperatures and low densities, compete with the growth of linear aggregates. The simplicity of the model makes it possible to compare simulation results and theoretical predictions based on the Wertheim perturbation theory, specialized to the case in which ring formation is allowed. Such a comparison offers a unique framework for establishing the quality of the analytic predictions. We find that the Wertheim theory describes remarkably well the simulation results.

Non-colorectal intestinal tract carcinomas in inflammatory bowel disease: results of the 3rd ECCO Pathogenesis Scientific Workshop (II)

Patients with inflammatory bowel diseases (IBD) have an excess risk of certain gastrointestinal cancers. Much work has focused on colon cancer in IBD patients, but comparatively less is known about other more rare cancers. The European Crohn's and Colitis Organization established a pathogenesis workshop to review what is known about these cancers and formulate proposals for future studies to address the most important knowledge gaps. This article reviews the current state of knowledge about small bowel adenocarcinoma, ileo-anal pouch and rectal cuff cancer, and anal/perianal fistula cancers in IBD patients.

Temperature-induced structural transitions in self-assembling magnetic nanocolloids

With the help of a unique combination of density functional theory and computer simulations, we discover two possible scenarios, depending on concentration, for the hierarchical self-assembly of magnetic nanoparticles on cooling. We show that typically considered low temperature clusters, i.e. defect-free chains and rings, merge into more complex branched structures through only three types of defects: four-way X junctions, three-way Y junctions and two-way Z junctions. Our accurate calculations reveal the predominance of weakly magnetically responsive rings cross-linked by X defects at the lowest temperatures. We thus provide a strategy to fine-tune magnetic and thermodynamic responses of magnetic nanocolloids to be used in medical and microfluidics applications.

Convergence to the European Energy Policy in European countries: case studies and comparison

Purpose – Our paper aims at analyzing how different European countries cope with the European Energy Policy, which proposes a set of measures (free energy market, smart meters, energy certificates) to improve energy utilization and management in Europe. Design/methodology/approach – The paper first reports the general vision, regulations and goals set up by Europe to implement the European Energy Policy. Later on, it performs an analysis of how some European countries are coping with the goals, with financial, legal, economical and regulatory measures. Finally, the paper draws a comparison between the countries to present a view on how Europe is responding to the emerging energy emergency of the modern world. Findings – Our analysis on different use cases (countries) showed that European countries are converging to a common energy policy, even though some countries appear to be later than others In particular, Southern European countries were slowed down by the world financial and economical crisis. Still, it appears that contingency plans were put into action, and Europe as a whole is proceeding steadily towards the common vision. Research limitations/implications – European countries are applying yet more cuts to financing green technologies, and it is not possible to predict clearly how each country will evolve its support to the European energy policy. Practical implications – Different countries applied the concepts and measures in different ways. The implementation of the European energy policy has to cope with the resulting plethora of regulations, and a company proposing enhancement regarding energy management still has to possess robust knowledge of the single country, before being able to export experience and know-how between European countries. Originality/Value – Even though a few surveys on energy measures in Europe are already part of the state-of-the-art, organic analysis diagonal to the different topics of the European Energy Policy is missing. Moreover, this paper highlights how European countries are converging on a common view, and provides some details on the differences between the countries, thus facilitating parties interesting into cross-country export of experience and technology for energy management.

Integrated Management of Cloud Computing Resources

Lunacloud is a cloud service provider with offices in Portugal, Spain, France and UK that focus on delivering reliable, elastic and low cost cloud Infrastructure as a Service (IaaS) solutions. The company currently relies on a proprietary IaaS platform - the Parallels Automation for Cloud Infrastructure (PACI) - and wishes to expand and integrate other IaaS solutions seamlessly, namely open source solutions. This is the challenge addressed in this thesis. This proposal, which was fostered by Eurocloud Portugal Association, contributes to the promotion of interoperability and standardisation in Cloud Computing. The goal is to investigate, propose and develop an interoperable open source solution with standard interfaces for the integrated management of IaaS Cloud Computing resources based on new as well as existing abstraction libraries or frameworks. The solution should provide bothWeb and application programming interfaces. The research conducted consisted of two surveys covering existing open source IaaS platforms and PACI (features and API) and open source IaaS abstraction solutions. The first study was focussed on the characteristics of most popular open source IaaS platforms, namely OpenNebula, OpenStack, CloudStack and Eucalyptus, as well as PACI and included a thorough inventory of the provided Application Programming Interfaces (API), i.e., offered operations, followed by a comparison of these platforms in order to establish their similarities and dissimilarities. The second study on existing open source interoperability solutions included the analysis of existing abstraction libraries and frameworks and their comparison. The approach proposed and adopted, which was supported on the conclusions of the carried surveys, reuses an existing open source abstraction solution – the Apache Deltacloud framework. Deltacloud relies on the development of software driver modules to interface with different IaaS platforms, officially provides and supports drivers to sixteen IaaS platform, including OpenNebula and OpenStack, and allows the development of new provider drivers. The latter functionality was used to develop a new Deltacloud driver for PACI. Furthermore, Deltacloud provides a Web dashboard and REpresentational State Transfer (REST) API interfaces. To evaluate the adopted solution, a test bed integrating OpenNebula, Open- Stack and PACI nodes was assembled and deployed. The tests conducted involved time elapsed and data payload measurements via the Deltacloud framework as well as via the pre-existing IaaS platform API. The Deltacloud framework behaved as expected, i.e., introduced additional delays, but no substantial overheads. Both the Web and the REST interfaces were tested and showed identical measurements. The developed interoperable solution for the seamless integration and provision of IaaS resources from PACI, OpenNebula and OpenStack IaaS platforms fulfils the specified requirements, i.e., provides Lunacloud with the ability to expand the range of adopted IaaS platforms and offers a Web dashboard and REST API for the integrated management. The contributions of this work include the surveys and comparisons made, the selection of the abstraction framework and, last, but not the least, the PACI driver developed.

Evaluation of penicillin therapy in patients with leptospirosis and acute renal failure

The effectiveness of specific antibiotic treatment in severe leptospirosis is still under debate. As part of a prospective study designed to evaluate renal function recovery after leptospirosis acute renal failure (ARF) (ARF was defined as Pcr > or = 1.5 mg/dL), the clinical evolutions of 16 treated patients (T) were compared to those of 18 untreated patients (nT). Treatment or non-treatment was the option of each patient's attending infectologist. The penicillin treatment was always with 6 million IU/day for 8 days. No difference was found between the two groups in terms of age, gender, number of days from onset of symptoms to hospital admission, or results of laboratory tests performed upon admission and during hospitalization, but proteinuria was higher in the treated group. There were no significant difference in the other parameters employed to evaluate patients' clinical evolution as: length of hospital stay, days of fever, days to normalization of renal function, days to total bilirubins normalized or reached 1/3 of maximum value and days to normalization of platelet counts. Dialytic treatment indication and mortality were similar between group T and nT. In conclusion, penicillin therapy did not provide better clinical outcome in patients with leptospirosis and ARF.

Evaluation of hemostasis disorders and anticardiolipin antibody in patients with severe leptospirosis

A prospective study was designed to evaluate disorders of hemostasis and levels of anticardiolipin antibodies (ACL) in 30 patients with severe leptospirosis and acute renal failure (ARF) (ARF was defined as serum creatinine > or = 1.5 mg/dL). The patients had been admitted to the Walter Cantídio University Hospital, São José Infectious Diseases Hospital and General Hospital of Fortaleza, Ceará, from August 1999 to July 2001. They all were male, with a mean age of 32 ± 14 years and with clinical and laboratory diagnoses of ARF leptospirosis. The time elapsed between onset of symptoms and the first hemorrhagic manifestation was 9 ± 4 days. Bleeding was observed in 86% of the patients. Laboratory tests showed significantly high levels of urea (181 ±95 mg/dl), fibrinogen, (515 ± 220 mg/dl), prothrombin time (13.3 ± 0.9 seconds) and low platelet counts (69 ± 65x10³/mm³) on admission. There was no elevation in activated partial thromboplastin time or thrombin time. Levels of IgM and IgG ACL concentrations were significantly increased (p < 0.05) in leptospirosis patients when compared to control patients (28.5 ± 32.4 vs. 11.5 ± 7.9MPL U/ml and 36.7 ± 36.1 vs. 6.5 ± 2.5 GPL U/ml), respectively. Vasculitis, thrombocytopenia and uremia should be considered important factors for the pathogenesis of hemorrhagic disturbances and the main cause of death in severe leptospirosis.

Acute renal failure after massive honeybee stings

Two clinical cases of patients who survived after numerous attacks of Africanized bees (600 and 1500 bee stings, respectively) are reported. Clinical manifestation was characterized by diffuse and widespread edema, a burning sensation in the skin, headache, weakness, dizziness, generalized paresthesia, somnolence and hypotension. Acute renal failure developed and was attributed to hypotension, intravascular hemolysis, myoglobinuria due to rhabdomyolysis and probably to direct toxic effect of the massive quantity of injected venom. They were treated with antihistaminic, corticosteroids and fluid infusion. One of them had severe acute renal failure and dialysis was required. No clinical complication was observed during hospital stay and complete renal function recovery was observed in both patients. In conclusion, acute renal failure after bee stings is probably due to pigment nephropathy associated with hypovolemia. Early recognition of this syndrome is crucial to the successful management of these patients.