Adherence to antibiotic treatment guidelines and outcomes in the hospitalized elderly with different types of pneumonia

Background: Few studies evaluated the clinical outcomes of Community Acquired Pneumonia (CAP), Hospital-Acquired Pneumonia (HAP) and Health Care-Associated Pneumonia (HCAP) in relation to the adherence of antibiotic treatment to the guidelines of the Infectious Diseases Society of America (IDSA) and the American Thoracic Society (ATS) in hospitalized elderly people (65 years or older). Methods: Data were obtained from REPOSI, a prospective registry held in 87 Italian internal medicine and geriatric wards. Patients with a diagnosis of pneumonia (ICD-9 480-487) or prescribed with an antibiotic for pneumonia as indication were selected. The empirical antibiotic regimen was defined to be adherent to guidelines if concordant with the treatment regimens recommended by IDSA/ATS for CAP, HAP, and HCAP. Outcomes were assessed by logistic regression models. Results: A diagnosis of pneumonia was made in 317 patients. Only 38.8% of them received an empirical antibiotic regimen that was adherent to guidelines. However, no significant association was found between adherence to guidelines and outcomes. Having HAP, older age, and higher CIRS severity index were the main factors associated with in-hospital mortality. Conclusions: The adherence to antibiotic treatment guidelines was poor, particularly for HAP and HCAP, suggesting the need for more adherence to the optimal management of antibiotics in the elderly with pneumonia

Nonlinear model standardization for the analysis and design of nonlinear systems with multiple equilibria

In engineering practice, a nonlinear system stable about several equilibria is often studied by linearizing the system over a small range of operation around each of these equilibria, and allowing the study of the system using linear system methods. Theoretically, for operations beyond a small range but still within the stable regime of an equilibrium, the system behaves nonlinearly, and can be described and investigated using the Volterra series approach. However, there is still no available approach that can systematically transform the model of a nonlinear system into a form that can be studied over the whole stable regime about an equilibrium so as to facilitate the system study using the Volterra series approach. This transformation is, in the present study, referred to as nonlinear model standardization, which is the extension of the well-known concept of linearization to the nonlinear case. In this paper, a novel approach to nonlinear model standardization is proposed for nonlinear systems that can be described by a Nonlinear AutoRegressive model with eXogeneous input (NARX) or a nonlinear differential equation (NDE) model. The proposed approach is then used in three case studies covering the applications in nonlinear system analysis, nonlinear system design, and nonlinearity compensation, respectively, demonstrating the significance of the proposed nonlinear model standardization in a wide range of engineering practices

Analysis of aerodynamics pressure measurements by dynamic coherent structures

none1Aerodynamic pressure measurements are usually interpreted through statistical tools involving modal representations. The most popular approach is based on the Principal Component Analysis (PCA), which provides the theoretical basis for the well-known concept of coherent structure. In order to overcome some theoretical and practical limitations, alternative approaches can be formulated adapting techniques developed in the feature-recognition field. In this sense, the Independent Component Analysis (ICA) can be conceived as an evolution of PCA in which high-order statistics are used to identify a non-orthogonal modal representation; ICA has been used to solve the Blind Source Separation (BSS) problem as well as to extract features from random data. Both PCA and ICA show severe limitations when applied to represent (and interpret) propagating phenomena such as the pressure field generated by a vortex advected by the mean flow. To overcome these problems, an explicit description of the time evolution is introduced in the modal representation through two techniques, Dynamic-PCA and Dynamic-ICA; besides, the novel concept of dynamic coherent structure is presented and used as an interpretative tool. The application of the above-mentioned methods is demonstrated referring to the aerodynamic pressure field measured on a bluff body immersed in a turbulent boundary layer.mixedL. CARASSALECarassale, Luig

Modelli discreti per lo studio della risposta di cavi eccitati dal vento

The nonlinear random oscillations of a cable induced by a turbulent wind are investigated proponing a discrete model, with quadratic-cubic nonlinearities and parametric excitation terms arising from geometric and aerodynamic effects. The formulation is independent of the order of discretization adopted for representing the cable motion and the turbulence field, as well as the order of the nonlinear terms retained in the expression of the aerodynamic force. A parametric analysis on a realistic model of suspended cable highlights the importance of the different classes of nonlinear terms enclosed in the model

Synthesis of multi-input Volterra systems by a topological assemblage scheme

The Volterra series expansion is widely employed to represent the input-output relationship of nonlinear dynamical systems. Such a representation is based on the Volterra frequency-response functions (VFRF), which can be calculated from the equation governing the system by the so-called harmonic probing method. This operation is straightforward for simple systems, may reach a prohibitive level of complexity for multiple-input systems when the calculation of a high-order VFRF is required. An alternative technique for the evaluation of the VFRFs of multiple-input systems is here presented generalizing an existing technique originally limited to the scalar case. A 2-dof mechanical example is used to illustrate the application of the technique