Changes in the dynamical behavior of nonlinear systems induced by noise.

Weak noise acting upon a nonlinear dynamical system can have far-reaching consequences. The fundamental underlying problem - that of large deviations of a nonlinear system away from a stable or metastable state, sometimes resulting in a transition to a new stationary state, in response to weak additive or multiplicative noise - has long attracted the attention of physicists. This is partly because of its wide applicability, and partly because it bears on the origins of temporal irreversibility in physical processes. During the last few years it has become apparent that, in a system far from thermal equilibrium, even small noise can also result in qualitative change in the system's properties, e.g., the transformation of an unstable equilibrium state into a stable one, and vice versa, the occurrence of multistability and multimodality, the appearance of a mean field, the excitation of noise-induced oscillations, and noise-induced transport (stochastic ratchets). A representative selection of such phenomena is discussed and analyzed, and recent progress made towards their understanding is reviewed

A discrete event simulation model to support bed management

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.In recent years, due to the overcrowding of Emergency Department (ED) and the growing concern in reducing the number of inpatient ward beds, it has become crucial to improve the capacity planning and control activities, which manage the patient flows from EDs to hospital wards. Bed Management has a key role in this context. This study starts by a collaboration with the Local Health Government (LHG) of the Liguria region aimed at studying the impact of supporting bed management with some operational strategies without increasing the bed capacity. A large amount of data was collected over a one-year period at public hospital in Genova and a preliminary observational analysis was conducted to get the main information about the flow of emergency and elective patients from ED to inpatient wards. A Discrete Event Simulation (DES) model has been then developed in order to represent the real system. A scenarios analysis is proposed to assess the best strategy to improve the system performance without increasing bed capacity, by simply synchronizing bed supply and demand. The model can be used as a decision support tool to optimise the use of the available resources as well as to improve the quality of the patient pathway inside the hospital.The authors acknowledge support from the Italian Ministry of Education, University and Research (MIUR), under the grand FIRB n. RBFR081KSB. Data have been made available thanks to a collaboration between ARS Liguria (Dr. Francesco Quaglia and Domenico Gallo) and the Department of Economics and Business, University of Genova

Improved unfolding by detrending of statistical fluctuations in quantum spectra

Accepted for publication in Physical Review EA fundamental relation exists between the statistical properties of the fluctuations of the energy level spectrum of a Hamiltonian and the chaotic properties of the physical system it describes. This relationship has been addressed previously as a signature of chaos in quantum dynamical systems. In order to properly analyze these fluctuations, however, it is necessary to separate them from the general tendency, namely, its secular part. Unfortunately this process, called unfolding, is not trivial and can lead to erroneous conclusions about the chaoticity of a system. In this paper we propose a technique to improve the unfolding procedure for the purpose of minimizing the dependence on the particular procedure. This technique is based on detrending the fluctuations of the unfolded spectra through the empirical mode decomposition method

Conceptual modelling of the flow of frail elderly through acute-care hospitals: An evidence-based management approach

This is the author accepted manuscript. The final version is available from Emerald via the DOI in this record.The ageing of the world’s population is causing an increase in the number of frail patients admitted to hospitals. In the absence of appropriate management and organisation, these patients risk an excessive length of stay and poor outcomes. To deal with this problem, we propose a conceptual model to facilitate the pathway of frail elderly patients across acute-care hospitals, focused on avoiding improper wait times and treatment during the process. The conceptual model is developed to enrich the standard flowchart of a clinical pathway in the hospital. The modified flowchart encompasses new organisational units and activities carried out by new dedicated professional roles. The proposed variant aims to provide a correct assessment of frailty at the entrance, a better management of the patient’s stay during different clinical stages and an early discharge, sending the patient home or to other facilities, avoiding a delayed discharge. The model is completed by a set of indicators aimed at measuring performance improvements and creating a strong database of evidence on the managing of frail elderly’s pathways, providing proper information that can validate the model when applied in current practice. The paper proposes a design of the clinical path of frail patients in acute-care hospitals, combining elements that, according to an evidence-based management approach, have proved to be effective in terms of outcomes, costs and organisational issues. We can therefore expect an improvement in the treatment of frail patients in hospital, avoiding their functional decline and worsening frailty conditions, as often happens in current practice following the standard path of other patients The framework proposed is a conceptual model to manage frail elderly patients in acute-care wards. Our research approach lacks application to real data and proof of effectiveness. Further work will be devoted to implementing a simulation model for a specific case study and verifying the impact of the conceptual model in real care settings. The framework proposed is a conceptual model to manage frail elderly patients in acute-care wards. Our research approach lacks application to real data and proof of effectiveness. Further work will be devoted to implementing a simulation model for a specific case study and verifying the impact of the conceptual model in real care settings. This paper fulfills an identified need to study and provide solutions for the management of frail elderly patients in acute-care hospitals, and generally to produce value in a patient-centred model

Nonlinear dynamics of coupled transverse-rotational waves in granular chains

The nonlinear dynamics of coupled waves in one-dimensional granular chains with and without a substrate is theoretically studied accounting for quadratic nonlinearity. The multiple time scale method is used to derive the nonlinear dispersion relations for infinite granular chains and to obtain the wave solutions for semiinfinite systems. It is shown that the sum-frequency and difference-frequency components of the coupled transverse-rotational waves are generated due to their nonlinear interactions with the longitudinal wave. Nonlinear resonances are not present in the chain with no substrate where these frequency components have low amplitudes and exhibit beating oscillations. In the chain positioned on a substrate two types of nonlinear resonances are predicted. At resonance, the fundamental frequency wave amplitudes decrease and the generated frequency component amplitudes increase along the chain, accompanied by the oscillations due to the wave numbers asynchronism. The results confirm the possibility of a highly efficient energy transfer between the waves of different frequencies, which could find applications in the design of acoustic devices for energy transfer and energy rectification

Methods for modelling the cost-effectiveness of interventions for prostate cancer: a systematic review - Protocol

This is a protocol for a systematic review of methods for modelling the cost-effectiveness of interventions for prostate cancer. It will aim to identify and bring together all health economic modelling studies in prostate cancer, to inform the subsequent development of a whole disease model for prostate cancer. This protocol is being deposited prospectively. The following review activities have been completed at the time of depositing: Bibliographic database search strategies designed (MEDLINE, Embase, NHSEED, HTA) Bibliographic database searches conducted and results combined into an EndNote library prepared for screening Random sample of 100 citations selected for pilot screening No further review activities have been initiated or completed at time of depositing

A genetic algorithm with composite chromosome for shift assignment of part-time employees

Personnel scheduling problems involve multiple tasks, including assigning shifts to workers. The purpose is usually to satisfy objectives and constraints arising from management, labour unions and employee preferences. The shift assignment problem is usually highly constrained and difficult to solve. The problem can be further complicated (i) if workers have mixed skills; (ii) if the start/end times of shifts are flexible; and (iii) if multiple criteria are considered when evaluating the quality of the assignment. This paper proposes a genetic algorithm using composite chromosome encoding to tackle the shift assignment problem that typically arises in retail stores, where most employees work part-time, have mixed-skills and require flexible shifts. Experiments on a number of problem instances extracted from a real-world retail store, show the effectiveness of the proposed approach in finding good-quality solutions. The computational results presented here also include a comparison with results obtained by formulating the problem as a mixed-integer linear programming model and then solving it with a commercial solver. Results show that the proposed genetic algorithm exhibits an effective and efficient performance in solving this difficult optimisation problem

NANOTECNOLOGÍA EN LA INDUSTRIA ALIMENTARIA: BIONANOCOMPUESTOS EN EMPAQUES DE ALIMENTICIOS

Most food industries use non-biodegradable packaging; and the application of bionanocompounds promises to expand the use of edible and biodegradable coating or covers for use in food products. The biopolymer or biodegradable plastics must maintain appropriate conditions of moisture, temperature and oxygen availability, without leaving any toxic residue. The biopolymers are classified into natural polymers and by microbial fermentation because of their prime material and fabrication. The bionanocompounds can be nanofillings based on cellulose, carbon nanotubes, nanoclays and functional nanofillings. These new technologies lead to ethical responsibility, where the covers do not cause harm to the environment and to consumers’ health. Based on this, a revision of the main characteristics of bionanocompounds in food packaging is presented.La mayoría de las industrias alimentarias utilizan envases no biodegradables y la aplicación de bionanocompuestos promete expandir el uso de películas o cubiertas comestibles y biodegradables para su uso en productos alimenticios. Los plásticos biopolímeros o biodegradables deben mantener condiciones apropiadas de humedad, temperatura y disponibilidad de oxígeno, sin dejar ningún residuo tóxico. Los biopolímeros por su materia prima y su fabricación se clasifican en biopolímeros naturales y por fermentación microbiana. Los bionanocompuestos pueden ser nanorellenos a base de celulosa, nanotubos de carbono, nanoarcillas y nanorellenos funcionales. Estas nuevas tecnologías llevan una responsabilidad ética donde las cubiertas no causen daño al ambiente y la salud de los consumidores. Con base en lo anterior, se presenta una revisión de las principales características de los bio nanocompuestos en los empaques de alimentos