Inversion of a SIR-based model: A critical analysis about the application to COVID-19 epidemic.

Calibration of a SIR (Susceptibles-Infected-Recovered) model with official international data for the COVID-19 pandemics provides a good example of the difficulties inherent in the solution of inverse problems. Inverse modeling is set up in a framework of discrete inverse problems, which explicitly considers the role and the relevance of data. Together with a physical vision of the model, the present work addresses numerically the issue of parameters calibration in SIR models, it discusses the uncertainties in the data provided by international authorities, how they influence the reliability of calibrated model parameters and, ultimately, of model predictions.

Life-threatening tumors of the heart in fetal and postnatal age.

OBJECTIVES: To evaluate the role of histology in diagnosis and management of biologically benign heart tumors causing life-threatening symptoms and even death in children and fetuses. The clinical impact of a multidisciplinary approach including 2-D echocardiography, histology, genetics, and cardiac surgery has not yet been fully elucidated. STUDY DESIGN: Forty-one consecutive antenatal (n = 17) or postnatal (n = 24) detected cardiac masses were evaluated by 2-D echocardiography (in alive patients) or at autopsy, and 12/41 cases with definite histologic diagnosis of primary and benign cardiac tumor were entered in this study. RESULTS: Rhabdomyomas (n = 6), hemangiomas (n = 3), central fibrous body chondroma (n = 1), fibroma (n = 1), or left atrial myxoma (n = 1) were histologically diagnosed in 4 fetuses and in 8 children. Death occurred in 6 patients showing diffuse or infiltrative tumors, 2/6 experiencing intrauterine death or sudden and unexpected infant death. Seven patients underwent surgery, 4/7 are alive and well at >5 years follow-up, whereas 3 deaths followed partial tumor resection. Two fetuses with extensive tumor/s were aborted. Tuberous sclerosis complex gene mutations were seen in patients with rhabdomyomas. CONCLUSIONS: Histology represents the best diagnostic approach in life-threatening pediatric cardiac tumors allowing definite diagnosis in cases other than rhabdomyoma and in sudden deaths, influencing clinical management and counselling. 2-D echocardiography remains the main tool for early clinical diagnosis and follow-up. A multidisciplinary approach is advisable because of rarity, difficult management, and possible associations with inheritable diseases.

CoViD-19, learning from the past: A wavelet and cross-correlation analysis of the epidemic dynamics looking to emergency calls and Twitter trends in Italian Lombardy region.

The first case of Coronavirus Disease 2019 in Italy was detected on February the 20th in Lombardy region. Since that date, Lombardy has been the most affected Italian region by the epidemic, and its healthcare system underwent a severe overload during the outbreak. From a public health point of view, therefore, it is fundamental to provide healthcare services with tools that can reveal possible new health system stress periods with a certain time anticipation, which is the main aim of the present study. Moreover, the sequence of law decrees to face the epidemic and the large amount of news generated in the population feelings of anxiety and suspicion. Considering this whole complex context, it is easily understandable how people "overcrowded" social media with messages dealing with the pandemic, and emergency numbers were overwhelmed by the calls. Thus, in order to find potential predictors of possible new health system overloads, we analysed data both from Twitter and emergency services comparing them to the daily infected time series at a regional level. Particularly, we performed a wavelet analysis in the time-frequency plane, to finely discriminate over time the anticipation capability of the considered potential predictors. In addition, a cross-correlation analysis has been performed to find a synthetic indicator of the time delay between the predictor and the infected time series. Our results show that Twitter data are more related to social and political dynamics, while the emergency calls trends can be further evaluated as a powerful tool to potentially forecast new stress periods. Since we analysed aggregated regional data, and taking into account also the huge geographical heterogeneity of the epidemic spread, a future perspective would be to conduct the same analysis on a more local basis.

Seawater intrusion in karstic, coastal aquifers: Current challenges and future scenarios in the Taranto area (southern Italy).

Mediterranean areas are characterized by complex hydrogeological systems, where management of freshwater resources, mostly stored in karstic, coastal aquifers, is necessary and requires the application of numerical tools to detect and prevent deterioration of groundwater, mostly caused by overexploitation. In the Taranto area (southern Italy), the deep, karstic aquifer is the only source of freshwater and satisfies the main human activities. Preserving quantity and quality of this system through management policies is so necessary and such task can be addressed through modeling tools which take into account human impacts and the effects of climate changes. A variable-density flow model was developed with SEAWAT to depict the "current" status of the saltwater intrusion, namely the status simulated over an average hydrogeological year. Considering the goals of this analysis and the scale at which the model was built, the equivalent porous medium approach was adopted to represent the deep aquifer. The effects that different flow boundary conditions along the coast have on the transport model were assessed. Furthermore, salinity stratification occurs within a strip spreading between 4km and 7km from the coast in the deep aquifer. The model predicts a similar phenomenon for some submarine freshwater springs and modeling outcomes were positively compared with measurements found in the literature. Two scenarios were simulated to assess the effects of decreased rainfall and increased pumping on saline intrusion. Major differences in the concentration field with respect to the "current" status were found where the hydraulic conductivity of the deep aquifer is higher and such differences are higher when Dirichlet flow boundary conditions are assigned. Furthermore, the Dirichlet boundary condition along the coast for transport modeling influences the concentration field in different scenarios at shallow depths; as such, concentration values simulated under stressed conditions are lower than those simulated under undisturbed conditions.

Is the forward problem of ground water hydrology always well posed?

Complex aquifer systems are often modeled with quasi-three-dimensional models, which consider two-dimensional horizontal flow in the aquifers and one-dimensional vertical flow through aquitards. When the aquifer system consists of a phreatic aquifer and one or more semiconfined aquifers connected by aquitards, the discrete model consists of a nonlinear system of algebraic equations, because the transmissivity of the phreatic aquifer depends on the phreatic head. If the water extraction is very high, the phreatic aquifer can be depleted and the equations of the model must be modified accordingly. There are not simple and general criteria to state if the phreatic aquifer is depleted before solving the system of equations. Therefore, the iterative procedures (e.g., relaxation methods), used to find the solution to the forward problem, must handle these particular conditions and can suffer several problems of convergence. These problems can be caused by the choice of the initial head values or of the relaxation coefficient of the iterative algorithms; however, they can also be caused by the nonexistence or nonuniqueness of the solution to the system of nonlinear equations. The study of existence and uniqueness of the general problem is very difficult and, therefore, we consider a simplified problem, for which the discrete model can be handled analytically. The results of the numerical experiments show that the solution to the forward problem can be nonunique. Only for some cases it is possible to invoke physical arguments to eliminate tentative solutions.

Squamous cell carcinoma of the prostate: long-term survival after combined chemo-radiation.

BACKGROUND: Carcinoma of the prostate gland is the most frequent malignant tumour affecting male population. While the large majority of tumours is represented by adenocarcinoma, pure squamous cell carcinoma comprises only 0.5-1% of all prostate neoplastic lesions. It is characterised by a high degree of malignancy, commonly metastasising to the bone (mainly with osteolytic lesions), liver and lungs with a median survival time of 14 months. Several therapeutic approaches have been employed in the effort to treat prostate pure squamous cell carcinoma, including radical surgery, radiotherapy, chemotherapy and hormonal therapy. All of them mostly failed to gain a significant survival benefit. CASE REPORT: We herein report on a case of pure squamous cell carcinoma of the prostate approached with combined-modality treatment, with the administration of 3 courses of cisplatin 75 mg/m(2) on day 1 and continuous infusion 5-fluorouracil 750 mg/m2 on day 1 to 5 and, subsequently, radiotherapy, with the delivery of a total dose of 46 Gy to the whole pelvis, with additional boost doses of 20 Gy to the prostatic bed and adjunctive 6 Gy to the prostate gland (72 Gy in total). The patient remained free of disease for 5 years, finally experiencing local relapse and, subsequently, dying of acute renal failure due to bilateral uretero-hydro-nephrosis. In addition, we provide a complete overview of all reported cases available within the medical literature. CONCLUSION: Since it remains questionable which should be the most appropriate therapeutic approach towards prostate pure squamous cell carcinoma, our report demonstrates that a prolonged disease control, with a consistent survival time, may be achieved by the combination of an effective local treatment such as radiotherapy with systemic infusion of chemotherapeutic drugs.