Transitions in active rotator systems: invariant hyperbolic manifold approach

Our main focus is on a general class of active rotators with mean field interactions, that is globally coupled large families of dynamical systems on the unit circle with non-trivial stochastic dynamics. Each isolated system is a diffusion process on a circle, with drift -delta V', where V' is a periodic function and delta is an intensity parameter. It is well known that the interacting dynamics is accurately described, in the limit of infinitely many interacting components, by a Fokker-Planck PDE and the model reduces for delta=0 to a particular case of the Kuramoto synchronization model, for which one can show the existence of a stable normally hyperbolic manifold of stationary solutions for the corresponding Fokker-Planck equation (we are interested in the case in which this manifold is non-trivial, that happens when the interaction is sufficiently strong, that is in the synchronized regime of the Kuramoto model). We use the robustness of normally hyperbolic structures to infer qualitative and quantitative results on the |delta|< delta0 cases, with delta0 a suitable threshold: as a matter of fact, we obtain an accurate description of the dynamics on the invariant manifold for delta=0 and we link it explicitly to the potential V . This approach allows to have a complete description of the phase diagram of the active rotators model, at least for |delta|< delta0, thus identifying for which values of the parameters (notably, noise intensity and/or coupling strength) the system exhibits periodic pulse waves or stabilizes at a quiescent resting state. Moreover, some of our results are very explicit and this brings a new insight into the combined effect of active rotator dynamics, noise and interaction. The links with the literature on specific systems, notably neuronal models, are discussed in detail.Comment: 29 pages, 4 figures. Version 2: some changes in introduction, added reference

Área de ocorrência do mexilhão dourado (Limnoperna fortunei) na bacia do Alto Paraguai, entre os anos de 1998 e 2004.

O uso de água armazenada nos grandes navios marítimos para obter maior estabilidade, ajudar na propulsão e em manobras, a chamada "água de lastro", é o principal meio de introdução de organismos marinhos em ambientes aquáticos, tanto marinhos como de água doce. Em todo o mundo são transferidas anualmente cerca de 12 bilhões de toneladas de "água de lastro", que transportam aproximadamente 4.500 espécies diferentes. No Brasil, aproximadamente 95% de todo o comércio exterior é feito por via marítima e estima-se que 40.000 navios visitem os portos brasileiros anualmente, deslastrando 40 milhões de toneladas de água por ano (Silva & Souza, 2004). Pela "água de lastro" a espécie de bivale de água doce Limnoperna fortunei (Dunker, 1857) foi introduzida no estuário do rio da Prata, em 1991, provavelmente trazido por navios da Korea e Hong Kong (Pastorino et al., 1993). E a navegação no sistema Paraguai-Paraná foi o principal vetor da introdução desta espécie na Bacia do Alto Paraguai, onde foi observada pela primeira vez em 1998, no rio Paraguai, próximo à cidade de Corumba (MS).bitstream/item/39645/1/DOC64.pd

Global attractor and asymptotic dynamics in the Kuramoto model for coupled noisy phase oscillators

We study the dynamics of the large N limit of the Kuramoto model of coupled phase oscillators, subject to white noise. We introduce the notion of shadow inertial manifold and we prove their existence for this model, supporting the fact that the long term dynamics of this model is finite dimensional. Following this, we prove that the global attractor of this model takes one of two forms. When coupling strength is below a critical value, the global attractor is a single equilibrium point corresponding to an incoherent state. Conversely, when coupling strength is beyond this critical value, the global attractor is a two-dimensional disk composed of radial trajectories connecting a saddle equilibrium (the incoherent state) to an invariant closed curve of locally stable equilibria (partially synchronized state). Our analysis hinges, on the one hand, upon sharp existence and uniqueness results and their consequence for the existence of a global attractor, and, on the other hand, on the study of the dynamics in the vicinity of the incoherent and synchronized equilibria. We prove in particular non-linear stability of each synchronized equilibrium, and normal hyperbolicity of the set of such equilibria. We explore mathematically and numerically several properties of the global attractor, in particular we discuss the limit of this attractor as noise intensity decreases to zero.Comment: revised version, 28 pages, 4 figure

Effects of alirocumab on types of myocardial infarction: insights from the ODYSSEY OUTCOMES trial

Aims  The third Universal Definition of Myocardial Infarction (MI) Task Force classified MIs into five types: Type 1, spontaneous; Type 2, related to oxygen supply/demand imbalance; Type 3, fatal without ascertainment of cardiac biomarkers; Type 4, related to percutaneous coronary intervention; and Type 5, related to coronary artery bypass surgery. Low-density lipoprotein cholesterol (LDL-C) reduction with statins and proprotein convertase subtilisin–kexin Type 9 (PCSK9) inhibitors reduces risk of MI, but less is known about effects on types of MI. ODYSSEY OUTCOMES compared the PCSK9 inhibitor alirocumab with placebo in 18 924 patients with recent acute coronary syndrome (ACS) and elevated LDL-C (≥1.8 mmol/L) despite intensive statin therapy. In a pre-specified analysis, we assessed the effects of alirocumab on types of MI. Methods and results  Median follow-up was 2.8 years. Myocardial infarction types were prospectively adjudicated and classified. Of 1860 total MIs, 1223 (65.8%) were adjudicated as Type 1, 386 (20.8%) as Type 2, and 244 (13.1%) as Type 4. Few events were Type 3 (n = 2) or Type 5 (n = 5). Alirocumab reduced first MIs [hazard ratio (HR) 0.85, 95% confidence interval (CI) 0.77–0.95; P = 0.003], with reductions in both Type 1 (HR 0.87, 95% CI 0.77–0.99; P = 0.032) and Type 2 (0.77, 0.61–0.97; P = 0.025), but not Type 4 MI. Conclusion  After ACS, alirocumab added to intensive statin therapy favourably impacted on Type 1 and 2 MIs. The data indicate for the first time that a lipid-lowering therapy can attenuate the risk of Type 2 MI. Low-density lipoprotein cholesterol reduction below levels achievable with statins is an effective preventive strategy for both MI types.For complete list of authors see http://dx.doi.org/10.1093/eurheartj/ehz299</p

Effect of alirocumab on mortality after acute coronary syndromes. An analysis of the ODYSSEY OUTCOMES randomized clinical trial

Background: Previous trials of PCSK9 (proprotein convertase subtilisin-kexin type 9) inhibitors demonstrated reductions in major adverse cardiovascular events, but not death. We assessed the effects of alirocumab on death after index acute coronary syndrome. Methods: ODYSSEY OUTCOMES (Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Alirocumab) was a double-blind, randomized comparison of alirocumab or placebo in 18 924 patients who had an ACS 1 to 12 months previously and elevated atherogenic lipoproteins despite intensive statin therapy. Alirocumab dose was blindly titrated to target achieved low-density lipoprotein cholesterol (LDL-C) between 25 and 50 mg/dL. We examined the effects of treatment on all-cause death and its components, cardiovascular and noncardiovascular death, with log-rank testing. Joint semiparametric models tested associations between nonfatal cardiovascular events and cardiovascular or noncardiovascular death. Results: Median follow-up was 2.8 years. Death occurred in 334 (3.5%) and 392 (4.1%) patients, respectively, in the alirocumab and placebo groups (hazard ratio [HR], 0.85; 95% CI, 0.73 to 0.98; P=0.03, nominal P value). This resulted from nonsignificantly fewer cardiovascular (240 [2.5%] vs 271 [2.9%]; HR, 0.88; 95% CI, 0.74 to 1.05; P=0.15) and noncardiovascular (94 [1.0%] vs 121 [1.3%]; HR, 0.77; 95% CI, 0.59 to 1.01; P=0.06) deaths with alirocumab. In a prespecified analysis of 8242 patients eligible for ≥3 years follow-up, alirocumab reduced death (HR, 0.78; 95% CI, 0.65 to 0.94; P=0.01). Patients with nonfatal cardiovascular events were at increased risk for cardiovascular and noncardiovascular deaths (P<0.0001 for the associations). Alirocumab reduced total nonfatal cardiovascular events (P<0.001) and thereby may have attenuated the number of cardiovascular and noncardiovascular deaths. A post hoc analysis found that, compared to patients with lower LDL-C, patients with baseline LDL-C ≥100 mg/dL (2.59 mmol/L) had a greater absolute risk of death and a larger mortality benefit from alirocumab (HR, 0.71; 95% CI, 0.56 to 0.90; Pinteraction=0.007). In the alirocumab group, all-cause death declined wit h achieved LDL-C at 4 months of treatment, to a level of approximately 30 mg/dL (adjusted P=0.017 for linear trend). Conclusions: Alirocumab added to intensive statin therapy has the potential to reduce death after acute coronary syndrome, particularly if treatment is maintained for ≥3 years, if baseline LDL-C is ≥100 mg/dL, or if achieved LDL-C is low. Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01663402

Magnetic stability against calcining of microwavesynthesized CoFe2O4 nanoparticles

High quality CoFe2O4 nanoparticles were synthesized using a one-pot, microwave assisted method, that allows forming stable colloidal solutions in alcoholic solvents, as required for the preparation by Chemical Solution Deposition of hybrid nanocomposite ferromagnetic-high Tc YBa2Cu3O7 superconducting films or devices. We have investigated how the thermal process necessary for the preparation of such epitaxial nanocomposites, involving high temperatures (800 °C) and oxygen partial pressures (1 atm), affects the structure and magnetic properties of the isolated nanoparticles. The NPs were fully characterised by XRD, SQUID, STEM-EELS and XMCD at four different stages of the thermal process. Results show that, despite intermediate changes in the cation distribution occur during the process, the final NP magnetization is stable against the thermal treatment. This result opens up perspectives for the preparation of hybrid YBCO films with embedded magnetic NPs using low-cost chemical-solution methodsAuthors acknowledge the MICIN (NANOSELECT, CSD2007-00041 and MAT2014-51778-C2-1-R and FEDER), Generalitat de Catalunya (2014SGR 753 and Xarmae), ‘‘Severo Ochoa’’ Programme for Centres of Excellence in R&D (SEV-2015-0496), the CONSOLIDER Excellence Network (MAT2015-68994-REDC) and the EU (EU-FP7 NMP-LA-2012- 280432 EUROTAPES project). Electron microscopy performed at the Centro Nacional de Microscopı´a Electro´nica (UCM) was sponsored by the ERC Starting Investigator Award No. STEMOX#239739. J. G. and M. C. also acknowledge the Ramon y Cajal program (RYC-2012- 11709, RYC-2013-12448). The XMCD experiments were performed at the BOREAS beamline of the ALBA Synchrotron Light Facility with the collaboration of ALBA staff.Peer reviewe

System Design Model for Versatile Outbreak Surveillance

Unlike usual surveillance systems, the ASTER system must provide a unified monitoring of several military populations exposed to different biological and chemical threats, and the surveillance of each population must be tailored to meet its specific risk profile. For coping with these requirements, we have developed a formal surveillance system model we have used for designing the system architecture and the webservices collaborations. The system currently covers populations in desertic areas as well as in Amazonian Forest. This versatility allowed a quick and easy system tailoring for the recent French Deployments in Jordanian Refugees Camps or in Mali