Properties of the Set of Hadamardized Hurwitz Polynomials

We say that a Hurwitz polynomial pt is a Hadamardized polynomial if there are two Hurwitz polynomials ft and gt such that f∗g=p, where f∗g is the Hadamard product of f and g. In this paper, we prove that the set of all Hadamardized Hurwitz polynomials is an open, unbounded, nonconvex, and arc-connected set. Furthermore, we give a result so that a fourth-degree Hurwitz interval polynomial is a Hadamardized polynomial family and we discuss an approach of differential topology in the study of the set of Hadamardized Hurwitz polynomials

Open problems related to the Hurwitz stability of polynomials segments

"In the framework of robust stability analysis of linear systems, the development of techniques and methods that help to obtain necessary and sufficient conditions to determine stability of convex combinations of polynomials is paramount. In this paper, knowing that Hurwitz polynomials set is not a convex set, a brief overview of some results and open problems concerning the stability of the convex combinations of Hurwitz polynomials is then provided.

Compilación de Proyectos de Investigación desde el año 2003 al 2012

Listado de Proyectos de investigación de UPIICSA desde 2003 a 201

Pneumonia treated in the internal medicine department: Focus on healthcare-associated pneumonia

Patients with pneumonia treated in the internal medicine department (IMD) are often at risk of healthcare-associated pneumonia (HCAP). The importance of HCAP is controversial. We invited physicians from 72 IMDs to report on all patients with pneumonia hospitalized in their department during 2weeks (one each in January and June 2010) to compare HCAP with community-acquired pneumonia (CAP) and hospital-acquired pneumonia (HAP). We analysed 1002 episodes of pneumonia: 58.9% were CAP, 30.6% were HCAP and 10.4% were HAP. A comparison between CAP, HCAP and HAP showed that HCAP patients were older (77, 83 and 80.5years; p<0.001), had poorer functional status (Barthel 100, 30 and 65; p<0.001) and had more risk factors for aspiration pneumonia (18, 50 and 34%; p<0.001). The frequency of testing to establish an aetiological diagnosis was lower among HCAP patients (87, 72 and 79; p<0.001), as was adherence to the therapeutic recommendations of guidelines (70, 23 and 56%; p<0.001). In-hospital mortality increased progressively between CAP, HCAP and HAP (8, 19 and 27%; p<0.001). Streptococcus pneumoniae was the main pathogen in CAP and HCAP. Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus (MRSA) caused 17 and 12.3% of HCAP. In patients with a confirmed aetiological diagnosis, the independent risk factors for pneumonia due do difficult-to-treat microorganisms (Enterobacteriaceae, P. aeruginosa or MRSA) were HCAP, chronic obstructive pulmonary diseases and higher Port Severity Index. Our data confirm the importance of maintaining high awareness of HCAP among patients treated in IMDs, because of the different aetiologies, therapy requirements and prognosis of this population. © 2011 The Authors. Clinical Microbiology and Infection © 2011 European Society of Clinical Microbiology and Infectious Diseases