1,720,973 research outputs found
Novel Stability Conditions for Nonlinear Monotone Systems and Consensus in Multi-Agent Networks
Full text linkWe introduce a novel definition of monotonicity, termed “type-K” in honor of Kamke, and study nonlinear type-K monotone dynamical systems possessing the plus-subhomogeneity property, which we call “K-subtopical” systems after Gunawardena and Keane. We show that type-K monotonicity, which is weaker than strong monotonicity, is also equivalent to monotonicity for smooth systems evolving in continuous-time, but not in discrete-time. K-subtopical systems are proved to converge toward equilibrium points, if any exists, generalizing the result of Angeli and Sontag about convergence of topical systems' trajectories toward the unique equilibrium point when strong monotonicity is considered. The theory provides an new methodology to study the consensus problem in nonlinear multi-agent systems (MASs). Necessary and sufficient conditions on the local interaction rule of the agents ensuring the K-subtopicality of MASs are provided, and consensus is proven to be achieved asymptotically by the agents under given connectivity assumptions on directed graphs. Examples in continuous-time and discrete-time corroborate the relevance of our results in different applications
Le carcinome papillare encapsulé de la thyroide: une entite clinique avec un bas degree de melignité.
No full textFactors predicting in-hospital mortality of patients with diffuse peritonitis from perforated colonic diverticulitis
No full textAim: Diverticulitis free perforation still remains a major life-threatening condition. Herein we evaluate factors influencing prognosis of patients with perforated colonic diverticulitis and the current validity of Mannheim Peritonitis Index (MPI) in predicting mortality. Material of Study: From January 2000 to October 2010, 39 patients were operated on for generalized peritonitis from perforated diverticulitis. Five postoperative deaths (12.8%) related to septic shock occurred. A cross-sectional study between deceased and non-deceased patients was carried out. Results: Deceased patients were significantly older than non-deceased (76.4 vs. 59.1 years, p=0.019); duration of symptoms was longer in deceased patients (102 vs. 26.9 hours, p=0.000); MPI was higher in deceased patients (31.4 vs. 21.2, p=0.000). Age, duration of symptoms and MPI were independent risk factors predicting poor prognosis. The highest sensitivity and specificity of MPI in predicting mortality was shown for a score >27. Conclusions: MPI is still effective in predicting postoperative mortality. People who nurse older persons must pay higher attention to complaints in order to reduce the delay in hospitalization
Distributed Fiedler Vector Estimation with Application to Desynchronization of Harmonic Oscillator Networks
Full text linkThe Fiedler vector of a graph is the eigenvector corresponding to the algebraic connectivity, which is the second-smallest eigenvalue (counting multiple eigenvalues separately) of the corresponding Laplacian matrix. We propose a continuous-time distributed control protocol to drive the value of the state variables of a network toward the Fiedler vector, up to a scale factor. Our protocol is unbiased and robust with respect to the initial network state, but the knowledge of the algebraic connectivity is required. By means of the proposed control law, we design a local state feedback that achieves desynchronization on arbitrary undirected connected networks of diffusively coupled harmonic oscillators. We provide numerical simulations to corroborate the theoretical results
A Sliding Mode Observer design for the Average State Estimation in Large-Scale Systems
Full text linkIn this letter the average state estimation problem on a large-scale system with only few gateway nodes available for measurements is solved as the design problem of a reduced-order sliding mode observer subjected to unmatched perturbations. Necessary and sufficient conditions to guarantee the exact estimation are derived. Still, even in the case such conditions are not fulfilled, the boundedness of the estimation error is proved. Finally, a criteria to minimize such bound, and a gain adaptation law to trade-off that bound and its convergence rate are provided. Neither the observer complexity nor the estimation error depend explicitly on the size of the system, thus making the approach scalable and computationally tractable. Simulations supporting the effectiveness of the proposed strategy and a comparison with other existing strategies are also provided
Rectal perforation from endometriosis in pregnancy: case report and literature review
Full text linkThis case report describes a woman with spontaneous rectal perforation from decidualized endometriosis in pregnancy. A 37-year-old woman was admitted to our hospital at 30 wk of pregnancy with symptoms suggestive of pyelonephritis, which persisted until 33 wk of gestation when delivery of a premature male baby was performed through a cesarean section. On postoperative day 2, an abdominal computed tomography showed free air in the peritoneal cavity and a pelvic abscess. Explorative celiotomy revealed a diffuse severe fecaloid peritonitis that originated from a 3-cm wide rectal perforation. A Hartmann operation was then performed. Histopathological findings were consistent with decidualization of the rectal wall. Only 20 cases of intestinal perforation due to endometriosis have been reported in the literature. This report is believed to be the first case of spontaneous rectal perforation from endometriosis in pregnancy, and it shows the potential occurrence of serious and unexpected complications of the disease
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