Institutional public private partnerships for core health services: evidence from Italy.

RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.BACKGROUND: Public-private partnerships (PPPs) are potential instruments to enable private collaboration in the health sector. Despite theoretical debate, empirical analyses have thus far tended to focus on the contractual or project dimension, overlooking institutional PPPs, i.e., formal legal entities run by proper corporate-governance mechanisms and jointly owned by public and private parties for the provision of public-health goods. This work aims to fill this gap by carrying out a comparative analysis of the reasons for the adoption of institutional PPPs and the governance and managerial features necessary to establish them as appropriate arrangements for public-health services provisions. METHODS: A qualitative analysis is carried out on experiences of institutional PPPs within the Italian National Health Service (Sistema Sanitario Nazionale, SSN). The research question is addressed through a contextual and comparative embedded case study design, assuming the entire population of PPPs (4) currently in force in one Italian region as the unit of analysis: (i) a rehabilitation hospital, (ii), an orthopaedic-centre, (iii) a primary care and ambulatory services facility, and (iv) a health- and social-care facility. Internal validity is guaranteed by the triangulation of sources in the data collection phase, which included archival and interview data. RESULTS: Four governance and managerial issues were found to be critical in determining the positive performance of the case examined: (i) a strategic market orientation to a specialised service area with sufficient potential demand, (ii) the allocation of public capital assets and the consistent financial involvement of the private partner, (iii) the adoption of private administrative procedures in a regulated setting while guaranteeing the respect of public administration principles, and (iv) clear regulation of the workforce to align the contracts with the organisational culture. CONCLUSIONS: Findings suggests that institutional PPPs enable national health services to reap great benefits when introduced as a complement to the traditional public-service provisions for a defined set of services and goals

Notions of explainability and evaluation approaches for explainable artificial intelligence

Explainable Artificial Intelligence (XAI) has experienced a significant growth over the last few years. This is due to the widespread application of machine learning, particularly deep learning, that has led to the development of highly accurate models that lack explainability and interpretability. A plethora of methods to tackle this problem have been proposed, developed and tested, coupled with several studies attempting to define the concept of explainability and its evaluation. This systematic review contributes to the body of knowledge by clustering all the scientific studies via a hierarchical system that classifies theories and notions related to the concept of explainability and the evaluation approaches for XAI methods. The structure of this hierarchy builds on top of an exhaustive analysis of existing taxonomies and peer-reviewed scientific material. Findings suggest that scholars have identified numerous notions and requirements that an explanation should meet in order to be easily understandable by end-users and to provide actionable information that can inform decision making. They have also suggested various approaches to assess to what degree machine-generated explanations meet these demands. Overall, these approaches can be clustered into human-centred evaluations and evaluations with more objective metrics. However, despite the vast body of knowledge developed around the concept of explainability, there is not a general consensus among scholars on how an explanation should be defined, and how its validity and reliability assessed. Eventually, this review concludes by critically discussing these gaps and limitations, and it defines future research directions with explainability as the starting component of any artificial intelligent system

Classification of Explainable Artificial Intelligence Methods through Their Output Formats

Machine and deep learning have proven their utility to generate data-driven models with high accuracy and precision. However, their non-linear, complex structures are often difficult to interpret. Consequently, many scholars have developed a plethora of methods to explain their functioning and the logic of their inferences. This systematic review aimed to organise these methods into a hierarchical classification system that builds upon and extends existing taxonomies by adding a significant dimension—the output formats. The reviewed scientific papers were retrieved by conducting an initial search on Google Scholar with the keywords “explainable artificial intelligence”; “explainable machine learning”; and “interpretable machine learning”. A subsequent iterative search was carried out by checking the bibliography of these articles. The addition of the dimension of the explanation format makes the proposed classification system a practical tool for scholars, supporting them to select the most suitable type of explanation format for the problem at hand. Given the wide variety of challenges faced by researchers, the existing XAI methods provide several solutions to meet the requirements that differ considerably between the users, problems and application fields of artificial intelligence (AI). The task of identifying the most appropriate explanation can be daunting, thus the need for a classification system that helps with the selection of methods. This work concludes by critically identifying the limitations of the formats of explanations and by providing recommendations and possible future research directions on how to build a more generally applicable XAI method. Future work should be flexible enough to meet the many requirements posed by the widespread use of AI in several fields, and the new regulation

A Quantitative Evaluation of Global, Rule-Based Explanations of Post-Hoc, Model Agnostic Methods

Understanding the inferences of data-driven, machine-learned models can be seen as a process that discloses the relationships between their input and output. These relationships consist and can be represented as a set of inference rules. However, the models usually do not explicit these rules to their end-users who, subsequently, perceive them as black-boxes and might not trust their predictions. Therefore, scholars have proposed several methods for extracting rules from data-driven machine-learned models to explain their logic. However, limited work exists on the evaluation and comparison of these methods. This study proposes a novel comparative approach to evaluate and compare the rulesets produced by five model-agnostic, post-hoc rule extractors by employing eight quantitative metrics. Eventually, the Friedman test was employed to check whether a method consistently performed better than the others, in terms of the selected metrics, and could be considered superior. Findings demonstrate that these metrics do not provide sufficient evidence to identify superior methods over the others. However, when used together, these metrics form a tool, applicable to every rule-extraction method and machine-learned models, that is, suitable to highlight the strengths and weaknesses of the rule-extractors in various applications in an objective and straightforward manner, without any human interventions. Thus, they are capable of successfully modelling distinctively aspects of explainability, providing to researchers and practitioners vital insights on what a model has learned during its training process and how it makes its predictions

Highly luminescent perovskite–aluminum oxide composites

In this communication we report on the preparation of CH3NH3PbBr3 perovskite/Al2O3 nanoparticle composites in a thin film configuration and demonstrate their high photoluminescence quantum yield. The composite material is solution-processed at low temperature, using stable alumina nanoparticle dispersions. There is a large influence of the alumina nanoparticle concentration on the perovskite morphology and on its photoluminescence

Perovskite solar cells prepared by flash evaporation

A simple vacuum deposition method for the preparation of high quality hybrid organic-inorganic methylammonium lead iodide perovskite thin films is reported. When sandwiched in between organic charge transporting layers, such films lead to solar cells with a power conversion efficiency of 12.2%

A comparative analysis of rule-based, model-agnostic methods for explainable artificial intelligence

The ultimate goal of Explainable Artificial Intelligence is to build models that possess both high accuracy and degree of explainability. Understanding the inferences of such models can be seen as a process that discloses the relationships between their input and output. These relationships can be represented as a set of inference rules which are usually not explicit within a model. Scholars have proposed several methods for extracting rules from data-driven machine-learned models. However, limited work exists on their comparison. This study proposes a novel comparative approach to evaluate and compare the rulesets produced by four post-hoc rule extractors by employing six quantitative metrics. Findings demonstrate that these metrics can actually help identify superior methods over the others thus are capable of successfully modelling distinctively aspects of explainability

Hybrid perovskites for light-emitting and photovoltaic devices

El objetivo de esta tesis es el desarrollo de métodos y materiales apropiados para la preparación de capas delgadas de perovskitas híbridas, y su implementación en dispositivos optoelectrónicos. Se dedicará particular atención a las relaciones entre la naturaleza del material, el método de deposición y las propiedades optoelectrónicas. El trabajo está organizado como sigue: - Células solares de perovskitas preparadas por evaporación flash. Se desarrolla un simple método de evaporación por la preparación de células solares. - Dispositivos de perovskita con alta eficiencia fotovoltaica y electroluminiscente. En este capítulo se presentan dispositivos optoelectrónicos de perovskitas preparados mediante co-evaporación que, además de presentar alta eficiencia fotovoltaica, lucen también electroluminiscencia. - Compuestos de perovskita-óxido de aluminio altamente luminiscentes. En este capítulo se presenta un método prometedor para el aumento del rendimiento cuántico de fotoluminiscencia. Cada capítulo se compone por una introducción del tema, seguida por una descripción detallada de las metodologías y por una discusión de los datos experimentales obtenidos. En el capítulo 2 se presentó la evaporación flash, una técnica novedosa para la deposición de capas aptas para ser implementadas en células solares. Para conseguir dispositivos eficientes, es esencial el perfeccionamiento del protocolo de evaporación. En particular, la calidad de la capa evaporada puede ser sustancialmente modificada dependiendo de la forma de la perovskita empleada como precursor. Los mejores resultados se obtuvieron cuando el material para evaporar es depositado en forma de capa delgada encima de la hoja de metal, asegurando un intercambio de calor uniforme entre metal y perovskita y causando la rápida evaporación del MAPbI3. Con este método se prepararon células solares caracterizadas por una eficiencia superior al 12% con capas activas de perovskita de tan sólo 250 nm de grosor. En el capítulo 3 se ha estudiado la relación entre fenómenos fotovoltaicos y electroluminiscentes en dispositivos de perovskitas. En particular se ha evidenciado como diodos de MAPbI3, empleados principalmente como células solares, pueden comportarse también cómo dispositivos emisores de luz. La electroluminiscencia de las perovskitas, a diferencia de la de los diodos orgánicos emisores de luz, es directamente proporcional a la densidad de corriente inyectada en el dispositivo. Por tanto, para aumentar la eficiencia de luminiscencia sin dañar los dispositivos por el estrés térmico que conlleva las altas corrientes, se ha medido el diodo de perovskita en corriente pulsada. De este modo, se ha podido obtener eficiencia doble comparada con la obtenida mediante corriente continua. Los resultados presentados en el capítulo 3 indican que las perovskitas tridimensionales de metilamonio se caracterizan por una alta concentración de trampas electrónicas, que disminuyen las recombinaciones radiativas afectando negativamente la eficiencia de la electroluminiscencia. Por esta razón, un incremento del rendimiento cuántico de fotoluminiscencia es necesario para la preparación de diodos de perovskitas emisores de luz. El capítulo 4 propone una estrategia para aumentar el PLQY de MAPbBr3, consistente en la preparación de compuestos de perovskita y Al2O3. Previamente se condujo un estudio para evaluar el efecto de la estequiometría de la perovskita, a través del cual se observó que un exceso de MABr ayuda a la formación de capas uniformes y compactas, y que además presentan un mayor PLQY. Cuando se añade el óxido de aluminio a la perovskita, el tamaño de los granos es reducido por efecto de la matriz de Al2O3, obteniendo un incremento del PLQY hasta el 39%. El comportamiento óptico de los compuestos perovskita-alúmina está dictado por la cantidad de Al2O3, y luminiscencia más intensa se ha alcanzado con el 50 wt.% de alúmina. En estas condiciones, el tiempo de vida y la constante radiativa de foto-luminiscencia se alargan gracias al mayor carácter excitónico de las nanopartículas de perovskitas, mientras que la componente no-radiativa se ve reducida por la pasivación de las trampas.The aim of this thesis was to develop methods as well as materials for the preparation of perovskite optoelectronic devices. A wide number of techniques have been employed for the preparation of perovskite thin-films, which have been implemented both in solar cells and light-emitting diodes. The flash evaporation, a novel method for the deposition of thin perovskite films suitable for solar cells have been presented in Chapter 2. The development of an optimized evaporation protocol is essential for the preparation of efficient devices. In particular, the evaporated film quality can be significantly influenced by the form of perovskite used as the precursor. It was found that if a thin perovskite layer is coated onto the metal foil (used as the heater), uniform heat exchange resulting in a homogeneous and fast film evaporation can be achieved. The best results were obtained when meniscus coating was employed to coat the metal heater. Under this condition, smooth and uniform perovskite films are readily deposited. When incorporated in multilayer solar cells, flash-evaporated perovskites lead to power conversion efficiency exceeding 12%, with an active layer thickness of only 250 nm. In Chapter 3, the relationship between photovoltaic and electroluminescence phenomena in perovskite devices have been discussed. In particular, it has been demonstrated that efficient MAPbI3 diodes prepared by dual source vacuum deposition, mainly studied for photovoltaic applications, also show intense electroluminescence when measured in forward bias. It has been observed that the electroluminescence efficiency of perovskite diodes is proportional to the current density injected in the device, as opposite to most OLEDs. In OLEDs the electroluminescence efficiency typically diminishes as the current density is increased, due to exciton-exciton annihilation. In perovskites, the low exciton binding energy leads to the formation of free carriers, hence the radiative band-to-band recombination is enhanced when trap states are filled at high current regimes. In order to increase the electroluminescence efficiency without thermal damage of the device at high currents, a pulsed driving mode was employed, which allows to obtain twice as high efficiency compared to the device biased in direct current. The results presented in Chapter 3 suggest that perovskites are characterized by a high concentration of traps that hinders radiative recombination hence limiting the electroluminescence efficiency. For this reason, the enhancement of the photoluminescence quantum yield (PLQY) is desirable for the preparation of efficient light-emitting diodes. In order to address this issue, the effect of the perovskite precursor stoichiometry and the addition of Al2O3 nanoparticles to the morphological and optical properties of MAPbBr3 has been investigated. Through a preliminary study it was demonstrated that an excess of MABr helps the formation of compact and uniform films, enhancing the PLQY most likely due to passivating effect of the excess precursor. Thanks to the high film quality, the correspondent light-emitting diodes showed intense electroluminescence and low leakage current, further confirming the potential of perovskites as light-emitting materials. When Al2O3 nanoparticles were added to non-stoichiometric perovskites, the grain size of the material was strongly reduced, resulting in an enhancement of the PLQY up to 39 %. The luminescence characteristics are strongly dependent on the amount of alumina blended with the MAPbBr3, with the most intense effect obtained for 50 wt.% loading in aluminum oxide. The incorporation of alumina also increases the PL lifetimes and the radiative rate constant, reducing the non-radiative path due to the passivation of traps states

Experimental Analysis of R134a and R1234ze(E) Flow Boiling Inside a Roll Bond Evaporator

Roll bond type evaporator is one of the most widely used technology in household refrigerators. Despite that, only few works that analyze the performance of this component are available in literature. Furthermore, no evidence is given to the impact on the heat transfer performance when substituting the original HFC refrigerant with an HFO inside the same evaporator. This paper presents an experimental study of R134a and R1234ze(E) inside an off the shelf roll bond evaporator, commonly used for small size domestic refrigerators. The evaporator was mounted inside a climate dark chamber where ambient temperature and humidity were maintained stable during the tests. To control the inlet conditions (evaporation temperature, inlet quality, refrigerant mass flow rate) it was used a water cooled miniature scale vapor cycle system with R134a and R1234ze(E) as working fluids. By means of an IR-thermo-camera, the whole roll bond temperature field was investigated under different working conditions. 15 thermocouples were collocated on the back of the evaporator to verify the temperatures reported in the images collected by the IR thermo-camera. From these pictures it was possible to delineate the super heating region and to point out the areas of the evaporator in which heat transfer is less efficient depending on the fluid and on the working conditions. During the experimental tests the refrigerant mass flow rate was varied by regulating the compressor speed, while ambient temperature and evaporation temperature were kept as constant. The data acquired from the vapor cycle system (i.e. condensation and evaporation pressure, evaporator inlet quality, vapour superheating, refrigerant mass flow rate) coupled with the IR thermo-camera images allowed to evaluate the behavior and the efficiency of the roll bond. Since the data were collected maintaining the same operating conditions in term of ambient temperature and humidity, heat flow rate and evaporation temperature, it was possible to highlight differences among the two refrigerants in term of mass flux. Furthermore, on the basis of the IR images and of the thermocouples measurements, an average heat transfer coefficient was defined and determined both on the air and the refrigerant side. The average heat transfer coefficients of the two refrigerants are compared and outlined in the paper