Lightweight and Effective Convolutional Neural Networks for Vehicle Viewpoint Estimation From Monocular Images

Vehicle viewpoint estimation from monocular images is a crucial component for autonomous driving vehicles and for fleet management applications. In this paper, we make several contributions to advance the state-of-the-art on this problem. We show the effectiveness of applying a smoothing filter to the output neurons of a Convolutional Neural Network (CNN) when estimating vehicle viewpoint. We point out the overlooked fact that, under the same viewpoint, the appearance of a vehicle is strongly influenced by its position in the image plane, which renders viewpoint estimation from appearance an ill-posed problem. We show how, by inserting in the model a CoordConv layer to provide the coordinates of the vehicle, we are able to solve such ambiguity and greatly increase performance. Finally, we introduce a new data augmentation technique that improves viewpoint estimation on vehicles that are closer to the camera or partially occluded. All these improvements let a lightweight CNN reach optimal results while keeping inference time low. An extensive evaluation on a viewpoint estimation benchmark and on actual vehicle camera data shows that our method significantly outperforms the state-of-the-art in vehicle viewpoint estimation, both in terms of accuracy and memory footprint

Development and Validation of a Comprehensive Model to Estimate Early Allograft Failure among Patients Requiring Early Liver Retransplant

Importance: Expansion of donor acceptance criteria for liver transplant increased the risk for early allograft failure (EAF), and although EAF prediction is pivotal to optimize transplant outcomes, there is no consensus on specific EAF indicators or timing to evaluate EAF. Recently, the Liver Graft Assessment Following Transplantation (L-GrAFT) algorithm, based on aspartate transaminase, bilirubin, platelet, and international normalized ratio kinetics, was developed from a single-center database gathered from 2002 to 2015. Objective: To develop and validate a simplified comprehensive model estimating at day 10 after liver transplant the EAF risk at day 90 (the Early Allograft Failure Simplified Estimation [EASE] score) and, secondarily, to identify early those patients with unsustainable EAF risk who are suitable for retransplant. Design, Setting, and Participants: This multicenter cohort study was designed to develop a score capturing a continuum from normal graft function to nonfunction after transplant. Both parenchymal and vascular factors, which provide an indication to list for retransplant, were included among the EAF determinants. The L-GrAFT kinetic approach was adopted and modified with fewer data entries and novel variables. The population included 1609 patients in Italy for the derivation set and 538 patients in the UK for the validation set; all were patients who underwent transplant in 2016 and 2017. Main Outcomes and Measures: Early allograft failure was defined as graft failure (codified by retransplant or death) for any reason within 90 days after transplant. Results: At day 90 after transplant, the incidence of EAF was 110 of 1609 patients (6.8%) in the derivation set and 41 of 538 patients (7.6%) in the external validation set. Median (interquartile range) ages were 57 (51-62) years in the derivation data set and 56 (49-62) years in the validation data set. The EASE score was developed through 17 entries derived from 8 variables, including the Model for End-stage Liver Disease score, blood transfusion, early thrombosis of hepatic vessels, and kinetic parameters of transaminases, platelet count, and bilirubin. Donor parameters (age, donation after cardiac death, and machine perfusion) were not associated with EAF risk. Results were adjusted for transplant center volume. In receiver operating characteristic curve analyses, the EASE score outperformed L-GrAFT, Model for Early Allograft Function, Early Allograft Dysfunction, Eurotransplant Donor Risk Index, donor age × Model for End-stage Liver Disease, and Donor Risk Index scores, estimating day 90 EAF in 87% (95% CI, 83%-91%) of cases in both the derivation data set and the internal validation data set. Patients could be stratified in 5 classes, with those in the highest class exhibiting unsustainable EAF risk. Conclusions and Relevance: This study found that the developed EASE score reliably estimated EAF risk. Knowledge of contributing factors may help clinicians to mitigate risk factors and guide them through the challenging clinical decision to allocate patients to early liver retransplant. The EASE score may be used in translational research across transplant centers

Physical activity in liver transplant recipients: a large multicenter study

Aim Healthy lifestyle and appropriate diet are of critical importance after liver transplant (LT). We provided an analysis of the main patterns of physical activity and found factors associated with physical activity itself.Methods Clinically stable LT recipients were enrolled between June and September 2021. Patients completed a composite questionnaire about physical activity, adherence to Mediterranean Diet (MD), quality of life (QoL), and employment. Correlations were analysed using the Pearson coefficients while different subgroups were compared by t-test for independent samples or ANOVAs. Multivariable logistic regression analysis was conducted to find predictors of inactivity.Results We enrolled 511 subjects (71% males, mean age 63 +/- 10.8 years). One hundred and ninety-three patients reported high level of physical activity, 197 a minimal activity and 121 declared insufficient activity. Among these latter, 29 subjects were totally inactive. Considering the 482 LT recipients performing some kind of physical activity, almost all reported a low-quality, non-structured activity. At multivariate analysis, time from LT (odds ratio 0.94, 95% CI 0.89-0.99, p = 0.017), sedentary lifestyle (odds ratio 0.99, 95% CI 0.19-0.81, p = 0.012), low adherence to MD (odds ratio 1.22, 95% CI 1.01-1.48, p = 0.049), and low level of QoL (physical dimension) (odds ratio 1.13, 95% CI 1.08-1.17, p < 0.001), were independently associated with total inactivity.Conclusion A large portion of LT recipients report an insufficient level of physical activity or are wholly inactive. Inactivity increases with time from LT and was strongly associated with suboptimal diet and low QoL

Quality of life in liver transplant recipients during the Corona virus disease 19 pandemic: A multicentre study

Background: Liver transplant recipients require specific clinical and psychosocial attention given their frailty. Main aim of the study was to assess the quality of life after liver transplant during the current pandemic. Methods: This multicentre study was conducted in clinically stable, liver transplanted patients. Enrollment opened in June and finished in September 2021. Patients completed a survey including lifestyle data, quality of life (Short Form health survey), sport, employment, diet. To examine the correlations, we calculated Pearson coefficients while to compare subgroups, independent samples t-tests and ANOVAs. To detect the predictors of impaired quality of life, we used multivariable logistic regression analysis. Results: We analysed data from 511 patients observing significant associations between quality of life’s physical score and both age and adherence to Mediterranean diet (p <.01). A significant negative correlation was observed between mental score and the sedentary activity (p <.05). Female patients scored significantly lower than males in physical and mental score. At multivariate analysis, females were 1.65 times more likely to report impaired physical score than males. Occupation and physical activity presented significant positive relation with quality of life. Adherence to Mediterranean diet was another relevant predictor. Regarding mental score, female patients were 1.78 times more likely to show impaired mental score in comparison with males. Sedentary activity and adherence to Mediterranean diet were further noteworthy predictors. Conclusions: Females and subjects with sedentary lifestyle or work inactive seem to show the worst quality of life and both physical activity and Mediterranean diet might be helpful to improve it

Integrated Planar Solid Oxide Fuel Cell: Steady-State Model of a Bundle and Validation through Single Tube Experimental Data

This work focuses on a steady-state model developed for an integrated planar solid oxide fuel cell (IP-SOFC) bundle. In this geometry, several single IP-SOFCs are deposited on a tube and electrically connected in series through interconnections. Then, several tubes are coupled to one another to form a full-sized bundle. A previously-developed and validated electrochemical model is the basis for the development of the tube model, taking into account in detail the presence of active cells, interconnections and dead areas. Mass and energy balance equations are written for the IP-SOFC tube, in the classical form adopted for chemical reactors. Based on the single tube model, a bundle model is developed. Model validation is presented based on single tube current-voltage (I-V) experimental data obtained in a wide range of experimental conditions, i.e., at different temperatures and for different H2/CO/CO2/CH4/H2O/N2 mixtures as the fuel feedstock. The error of the simulation results versus I-V experimental data is less than 1% in most cases, and it grows to a value of 8% only in one case, which is discussed in detail. Finally, we report model predictions of the current density distribution and temperature distribution in a bundle, the latter being a key aspect in view of the mechanical integrity of the IP-SOFC structure