Robust dynamic traffic assignment for single destination networks under demand and capacity uncertainty

In this article, we discuss the system-optimum dynamic traffic assignment (SO-DTA) problem in the presence of time-dependent uncertainties on both traffic demands and road link capacities. Building on an earlier formulation of the problem based on the cell transmission model, the SO-DTA problem is robustly solved, in a probabilistic sense, within the framework of random convex programs (RCPs). Different from traditional robust optimization schemes, which find a solution that is valid for all the values of the uncertain parameters, in the RCP approach we use a fixed number of random realizations of the uncertainty, and we are able to guarantee a priori a desired upper bound on the probability that a new, unseen realization of the uncertainty would make the computed solution unfeasible. The particular problem structure and the introduction of an effective domination criterion for discarding a large number of generated samples enables the computation of a robust solution for medium- to large-scale networks, with low desired violation probability, with a moderate computational effort. The proposed approach is quite general and applicable to any problem that can be formulated through a linear programing model, where the stochastic parameters appear in the constraint constant terms only. Simulation results corroborate the effectiveness of our approach

Photo-induced second-order nonlinearity in stoichiometric silicon nitride waveguides

We report the observation of second-harmonic generation in stoichiometric silicon nitride waveguides grown via low-pressure chemical vapour deposition. Quasi-rectangular waveguides with a large cross section were used, with a height of 1 {\mu}m and various different widths, from 0.6 to 1.2 {\mu}m, and with various lengths from 22 to 74 mm. Using a mode-locked laser delivering 6-ps pulses at 1064 nm wavelength with a repetition rate of 20 MHz, 15% of the incoming power was coupled through the waveguide, making maximum average powers of up to 15 mW available in the waveguide. Second-harmonic output was observed with a delay of minutes to several hours after the initial turn-on of pump radiation, showing a fast growth rate between 10$^{-4}$ to 10$^{-2}$ s$^{-1}$, with the shortest delay and highest growth rate at the highest input power. After this first, initial build-up, the second-harmonic became generated instantly with each new turn-on of the pump laser power. Phase matching was found to be present independent of the used waveguide width, although the latter changes the fundamental and second-harmonic phase velocities. We address the presence of a second-order nonlinearity and phase matching, involving an initial, power-dependent build-up, to the coherent photogalvanic effect. The effect, via the third-order nonlinearity and multiphoton absorption leads to a spatially patterned charge separation, which generates a spatially periodic, semi-permanent, DC-field-induced second-order susceptibility with a period that is appropriate for quasi-phase matching. The maximum measured second-harmonic conversion efficiency amounts to 0.4% in a waveguide with 0.9 x 1 {\mu}m$^2$ cross section and 36 mm length, corresponding to 53 {\mu}W at 532 nm with 13 mW of IR input coupled into the waveguide. The according $\chi^{(2)}$ amounts to 3.7 pm/V, as retrieved from the measured conversion efficiency.Comment: 20 pages, 10 figure

Forecasting Network Traffic: A Survey and Tutorial with Open-Source Comparative Evaluation

This paper presents a review of the literature on network traffic prediction, while also serving as a tutorial to the topic. We examine works based on autoregressive moving average models, like ARMA, ARIMA and SARIMA, as well as works based on Artifical Neural Networks approaches, such as RNN, LSTM, GRU, and CNN. In all cases, we provide a complete and self-contained presentation of the mathematical foundations of each technique, which allows the reader to get a full understanding of the operation of the different proposed methods. Further, we perform numerical experiments based on real data sets, which allows comparing the various approaches directly in terms of fitting quality and computational costs. We make our code publicly available, so that readers can readily access a wide range of forecasting tools, and possibly use them as benchmarks for more advanced solutions

Osteoporosis guidelines from a rehabilitation perspective: systematic analysis and quality appraisal using AGREE II

Background: People affected by osteoporosis and fragility fractures often report disability and poor health-related quality of life. Albeit rehabilitation has a crucial role in older people, post-menopausal women and other subjects with high risk of fragility fractures, the rehabilitation perspective has been poorly investigated in the available guidelines for osteoporosis. Aim: To systematically evaluate the quality of guidelines for osteoporosis from a rehabilitation perspective. Design: Systematic analysis of guidelines. Setting: Not applicable. Population: Osteoporotic patients. Methods: On May 2020, we performed a systematic search on medical literature of all guidelines published in the last 10 years on PubMed, PEDro, and international guideline databases. The study selection was based on key terms "exercise", "physical activity" or "rehabilitation". All authors independently assessed the methodological quality through the Appraisal of Guidelines for Research & Evaluation (AGREE) II instrument, consisting of six domains (scope, stakeholder involvement, rigor and development, clarity of presentation, applicability, editorial independence). Results: Out of 331 documents retrieved, a total of 34 guidelines were selected after the screening phases. Twenty (58.8%) high quality guidelines were reported. According to AGREE II instrument, a mean score of 78.1±21.8% was reported for "scope and purpose" domain; for stakeholder involvement, the mean score was 58.1±22.1%; the rigor of development was good (mean score of 61.3±27.3%); for clarity of presentation the mean score was 79.4±20.3%; the applicability was poor (mean score of 30.9±25.2%); for editorial independence the mean score was 75.1±24.6%. Rehabilitation recommendations for osteoporotic patients were reported in 21 (61.8%) of the selected guidelines. Conclusions: This is the first systematic analysis evaluating quality of the guidelines for osteoporosis using AGREE II instrument. Starting from a state of the art of the currently available evidence, we could conclude that therapeutic exercise at moderate to high intensity is encouraged by several guidelines for the management of people with osteoporosis and fragility fractures. More than half of guidelines were of high-quality. However, most guidelines are lacking specific indications about exercise features. Clinical rehabilitation impact: This study might support the implementation of a rehabilitation perspective in the guidelines for osteoporotic patients

A Joint Optimization Approach for Power-Efficient Heterogeneous OFDMA Radio Access Networks

Heterogeneous networks have emerged as a popular solution for accommodating the growing number of connected devices and increasing traffic demands in cellular networks. While offering broader coverage, higher capacity, and lower latency, the escalating energy consumption poses sustainability challenges. In this paper a novel optimization approach for orthogonal heterogeneous networks is proposed to minimize transmission power while respecting individual users' throughput constraints. The problem is formulated as a mixed integer geometric program, and optimizes at once multiple system variables such as user association, working bandwidth, and base stations transmission powers. Crucially, the proposed approach becomes a convex optimization problem when user-base station associations are provided. Evaluations in multiple realistic scenarios from the production mobile network of a major European operator and based on precise channel gains and throughput requirements from measured data validate the effectiveness of the proposed approach. Overall, our original solution paves the road for greener connectivity by reducing the energy footprint of heterogeneous mobile networks, hence fostering more sustainable communication systems.TRUEpu

A Joint Optimization Approach for Power-Efficient Heterogeneous OFDMA Radio Access Networks

Heterogeneous networks have emerged as a popular solution for accommodating the growing number of connected devices and increasing traffic demands in cellular networks. While offering broader coverage, higher capacity, and lower latency, the escalating energy consumption poses sustainability challenges. In this paper a novel optimization approach for OFDMA heterogeneous networks is proposed to minimize transmission power while respecting individual users throughput constraints. The problem is formulated as a mixed integer geometric program, and optimizes at once multiple system variables such as user association, working bandwidth, and base stations transmission powers. Crucially, the proposed approach becomes a convex optimization problem when user-base station associations are provided. Evaluations in multiple realistic scenarios from the production mobile network of a major European operator and based on precise channel gains and throughput requirements from measured data validate the effectiveness of the proposed approach. Overall, our original solution paves the road for greener connectivity by reducing the energy footprint of heterogeneous mobile networks, hence fostering more sustainable communication systems

Surgical bleeding after pre-operative unfractionated heparin and low molecular weight heparin for coronary bypass surgery

Background and Objectives Since the impairment of platelet function may cause excess peri-operative bleeding, pre-operative discontinuation of aspirin and heparin bridging are common for cardiac surgery. We evaluated the impact of pre-operative administration of enoxaparin and unfractionated heparin (UFH) on coagulation parameters and peri-operative bleeding in patients undergoing elective coronary artery bypass grafting (CABG) surgery after discontinuation of aspirin. Design and Methods Forty-three patients with three-vessel coronary artery disease undergoing elective CABG surgery discontinued aspirin and were randomized to receive either UFH 180 UI/Kg × 2/day s.c. or enoxaparin 100 UI/Kg × 2/day s.c. until 12 h before surgery (median pre-operative treatment 8 days, range 6–12 days). Surgery was performed as usual with UFH. Neither UFH nor any low molecular weight heparin was given in the immediate post-operative period. The effects of UFH and enoxaparin were monitored by the activated partial thromboplastin time (aPTT) and the Enox-test (sensitive to factor Xa inhibition) using a Rapidpoint® Coagulation Analyzer. aPTT and factor Xa activity were also measured by standard methods. Peri-operative bleeding and the nadirs of hemoglobin concentration, hematocrit and platelet count were monitored post-operatively. Results Patients in the two groups were similar for number of bypasses, on-pump time, total surgery time, and time from the last heparin administration. Coagulation parameters increased significantly and similarly at 30 min and 6 h with both treatments, but returned within the normal range at 12 h. Hemoglobin, hematocrit and platelet counts significantly decreased to the same extent after CABG and re-normalized at the same time. Transfusional requirements of blood and plasma units were similar in the two groups. Interpretation and Conclusions From the kinetics of coagulation parameters and the evaluation of bleeding, enoxaparin is a safe alternative to UFH as a bridging therapy to CABG after discontinuation of aspirin

Prognostic role of endocarditis in isolated tricuspid valve surgery. A propensity-weighted study

Objectives The role of the underlying etiology in isolated tricuspid valve surgery has not been investigated extensively in current literature. Aim of this study was to analyse outcomes of patients undergoing surgery due to endocarditis compared to other pathologies. Methods The SURTRI study is a multicenter study enrolling adult patients who underwent isolated tricuspid valve surgery (n = 406, 55 ± 16 y.o.; 56% female) at 13 international sites. Propensity weighted analysis was performed to compare groups (IE group n = 107 vs Not-IE group n = 299). Results No difference was found regarding the 30-day mortality (Group IE: 2.8% vs Group Not-IE = 6.8%; OR = 0.45) and major adverse events. Weighted cumulative incidence of cardiac death was significantly higher for patients with endocarditis (p = 0.01). The composite endpoint of cardiac death and reoperation at 6 years was reduced in the Group IE (63.2 ± 6.8% vs 78.9 ± 3.1%; p = 0.022). Repair strategy resulted in an increased late survival even in IE cases. Conclusions Data from SURTRI study report acceptable 30-day results but significantly reduced late survival in the setting of endocarditis of the tricuspid valve. Multi-disciplinary approach, repair strategy and earlier treatment may improve outcomes. © 2022 The Author

Pb effects on an experimental model of porcine prepubertal Sertoli cells

The environmental pollution is one of the main factors implicated in the world’s fertility decline. Lead (Pb) is one of the major heavy metal contaminants that impairs several organs but preferentially accumulates in male reproductive organs and alters in vivo and in vitro sperm quality [1]. Nowadays, the underlying mechanisms remain unclear. Sertoli cells (SC) provides structural and metabolic support to the spermatogenic cells within the seminiferous tubules, therefore, metabolic and structural changes in SC affect the developing germ cells and consequently alter spermatogenesis. This study aimed to assess whether exposure to subtoxic doses of Pb would adversely affect superior mammalian SC function. Highly purified and functional porcine pre-pubertal SC were isolated [2] and treated with three different Pb acetate concentrations. Parameters of SC functionality, such as inhibin B and anti-Müllerian hormone (AMH) mRNAs and proteins were decreased by Pb exposure respect to the control, such as the FSH-r integrity in terms of 17-β-estradiol production, under FSH stimulation. In addition, we observed an increase of AKT and mTOR mRNAs, p38 phosphorylation ratio and Akt phosphorylation ratio in all experimental conditions, respect to the control. In conclusion, the Pb-related toxicity on SC, even at low concentrations, is expected to alter spermatogenesis