The influence of different building types on the activity concentration of Radon indoor is studied through transport models in soil and building materials. The numerical solutions of the relevant ...transport equations are solved by the finite differences method (FDM) and used to evaluate the indoor Radon activity concentration. Several boundary conditions are introduced to simulate the Radon entry into the buildings from soils and to assess the Radon activity concentration at the different floors. The types of dwelling investigated differ in the position of the lower floor respect to the ground. Comparisons are made to modeling assessments obtained considering different soil characteristics underneath the building and building materials to simulate indoor Radon activity concentration. These investigations lead to the conclusion that, in addition to the nature of the soil and building materials, the position of lower floor of dwellings plays a significant role in determining the amount of radon entry into residential buildings. This work is effective to assess the health hazards coming from the Radon accumulation in living environments.
•Evaluation of Radon indoor at different dwelling floors through transport models.•Radon indoor is simulated by varying soils characteristics and building materials.•Finite differences method (FDM) is used to solve the transport models equations.•The position of lower floor of dwellings plays a significant role.•Radon activity concentrations increase using yellow tuff.
The COVID-19 pandemic is spreading worldwide. Italy emerged early on as the country with the largest outbreak outside Asia. The outbreak in Northern Italy demonstrates that it is fundamental to ...contain the virus' spread at a very early stage of diffusion. At later stages, no containment measure, even if strict, can prevent the saturation of the hospitals and of the intensive care units in any country. Here we show that it is possible to predict when the intensive care units will saturate, within a few days from the beginning of the exponential growth of COVID-19 intensive care patients. Using early counts of intensive care patients, we predict the saturation for Lombardy, Italy. We also assess short-term and long-term lockdown effects on intensive care units and number of deaths. Governments should use the Italian outbreak as a precedent and implement appropriate containment measures to prevent the saturation of their intensive care units and protect their population, also, and above all, in anticipation of a possible second exponential spread of infections.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this paper, we study the use of a pulse vaccination strategy to eradicate infectious diseases modelizable by SIR epidemic model. We demonstrate the global asymptotic stability of the eradication ...solution (which was conjectured by Agur and coworkers in 1 for pulse vaccination in the classical SIR model) for a general model in which nonpermanent immunization, variations of the total population size, and the emerging problem of the vaccine failures are considered. As a strategy using a second inoculation is a standard practice, we propose a model to describe a modification of this strategy including the second inoculation and we study its local asymptotic stability.
Abstract
OBJECTIVES
Transapical Neochordae implantation (NC) allows beating heart mitral valve repair in patients with degenerative mitral regurgitation. The aim of this single-centre, retrospective ...study was to compare outcomes of NC versus conventional surgical (CS) mitral valve repair.
METHODS
Data of patients who underwent isolated mitral valve repair with NC or CS from January 2010 to December 2018 were collected. A propensity score matching analysis was performed to reduce confounding due to baseline differences between groups. The primary end point was overall all-cause mortality; secondary end points were freedom from reoperation, freedom from moderate (2+) and from severe (3+) mitral regurgitation (MR) and New York Heart Association functional class in the overall population and in patients with isolated P2 prolapse (type A anatomy).
RESULTS
Propensity analysis selected 88 matched pairs. There was no 30-day mortality in the 2 groups. Kaplan–Meier analysis showed similar 5-year survival in the 2 groups. Patients undergoing NC showed worse freedom from moderate MR (≥2+) (57.6% vs 84.6%; P < 0.001) and from severe MR (3+) at 5-year follow-up: 78.1% vs 89.7% (P = 0.032). In patients with type A anatomy, freedom from moderate MR and from severe MR was similar between groups (moderate: 63.9% vs 74.6%; P = 0.21; severe: 79.3% vs 79%; P = 0.77 in NC and FS, respectively). Freedom from reoperation was lower in the NC group: 78.9% vs 92% (P = 0.022) but, in type A patients, it was similar: 79.7% and 85% (P = 0.75) in the NC and CS group, respectively. More than 90% of patients of both groups were in New York Heart Association class I and II at follow-up.
CONCLUSIONS
Transapical beating-heart mitral chordae implantation can be considered as an alternative treatment to CS, especially in patients with isolated P2 prolapse
Surgical mitral valve repair is the gold standard treatment for degenerative mitral regurgitation (DMR), since it provides excellent long-term clinical and echocardiographic results and it is currently recommended by guidelines 1–11.
•We propose a new model for the time–space evolution of vascularized tumors•The model encompasses tumor aggression to healthy cells, generation and dynamics of the endothelial cells that form the ...tumor neovasculature.•Detailed derivation of a new general family of models of the tumoral angiogenesis-related chemotaxis by means of a velocity-jump random walk model.•The dynamics of oxygen concentration and of a tumor proangiogenic factor is modeled, taking into account a crowding effect that impairs proliferation and cells mobility.•Analytical study of non-negativity of all variables and of post-invasion steady state.
This work considers the propagation of a tumor from the stage of a small avascular sphere in a host tissue and the progressive onset of a tumor neovasculature stimulated by a pro-angiogenic factor secreted by hypoxic cells. The way new vessels are formed involves cell sprouting from pre-existing vessels and following a trail via a chemotactic mechanism (CM). Namely, it is first proposed a detailed general family of models of the CM, based on a statistical mechanics approach. The key hypothesis is that the CM is composed by two components: i) the well–known bias induced by the angiogenic factor gradient; ii) the presence of stochastic changes of the velocity direction, thus giving rise to a diffusive component. Then, some further assumptions and simplifications are applied in order to derive a specific model to be used in the simulations. The tumor progression is favored by its acidic aggression towards the healthy cells. The model includes the evolution of many biological and chemical species. Numerical simulations show the onset of a traveling wave eventually replacing the host tissue with a fully vascularized tumor. The results of simulations agree with experimental measures of the vasculature density in tumors, even in the case of particularly hypoxic tumors.
Highlights • A novel method to develop a bone substitute is shown. • Bioactive glasses are used as precursor to form calcium phosphate cements. • Strontium addition in the glass has positive effects ...on cement's properties.
SIR and SIS epidemic models with information—related changes in contact patterns are introduced. The global stability analysis of the endemic equilibrium is performed by means of the Li–Muldowney ...geometric approach. Biological implications of the stability conditions are given.
Cardiac surgery associated acute kidney injury (CSA-AKI) is a significant clinical problem. Its pathogenesis is complex and multifactorial. It likely involved at least six major injury pathways: ...exogenous and endogenous toxins, metabolic factors, ischemia and reperfusion, neurohormonal activation, inflammation and oxidative stress. These mechanisms of injury are likely to be active at different times with different intensity and probably act synergistically. Because of such complexity and the small number of randomised controlled investigations in this field only limited recommendations can be made. Nonetheless, it appears important to avoid nephrotoxic drugs and desirable to avoid hyperglycemia in the peri-operative period. The duration of cardiopulmonary bypass should be limited whenever possible. Off-pump surgery, when indicated, may decrease the risk of AKI. Invasive hemodynamic monitoring focussed on attention to maintaining euvolemia, an adequate cardiac output and an adequate arterial blood pressure is desirable. Echocardiography may be useful in minimizing atheroembolic complications. The administration of N-acetylcysteine to protect the kidney from oxidative stress is not recommended. There is marked lack of randomised controlled trials in this field.
Several lead objects were found gilded at the Royal Palace in Caserta (1752, Italy) and the gilding technique of nine of them was analysed. Historical research shows that lead was used because of its ...easy workability, wide availability, and low cost, and was also gilded like wood or stucco. XRF analysis made it possible to determine the elemental composition of the layering created for gilding, highlighting its characteristics and differences. Standard samples with similar features were made for the characterization of the stratigraphy of interest through the XRF technique. The novelty found in this study is that lead was also gilded using the gouache technique, that is a layering with gesso, Armenian bolus and gold leaf. The restoration interventions carried out in the past were highlighted. The results found are very useful for museum conservators and restorers as well as for research. KEYWORDS: Gilding on lead, Gouache gilding, Lead artworks, Royal Palace in Caserta, XRF technique.
El presente trabajo analiza la legislación de Argentina, Brasil, Chile, Colombia, España, Estados Unidos, Francia y Reino Unido, que hace alguna referencia a los programas de integridad y la utilidad ...de los mismos frente a la prevención de delitos relacionados con la corrupción administrativa.
El desarrollo del mismo se enmarca dentro del proyecto de Desarrollo Estratégico (PDE) de la Universidad de Buenos Aires, denominado PDE_9_2019 “Corrupción, fraude empresario y sistemas de cumplimiento en las organizaciones” que tiene por fin demostrar que programa de integridad que funciona eficazmente previene ampliamente las situaciones de corrupción.
Entendemos que estos temas son de extrema relevancia en el contexto actual de pandemia que ha obligado a las organizaciones a modificar ciertos procedimientos.
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