Testing approaches for global optimization of space trajectories

In this paper the procedures to test global search algorithms applied to space trajectory design problems are discussed. Furthermore, a number of performance indexes that can be used to evaluate the effectiveness of the tested algorithms are presented. The performance indexes are then compared and the actual significance of each one of them is highlighted. Three global optimization algorithms are tested on three typical space trajectory design problems

Aerodynamic design optimization of wind turbine airfoils under aleatory and epistemic uncertainty

This paper presents different approaches to optimize wind turbine airfoils in an uncertain scenario. The approaches are specifically applied to the aerodynamic design optimization of a wind turbine airfoil accounting for the uncertainty in setting up the XFOIL's NCRIT constant: a parameter that is considered affected by a chain of aleatory and epistemic uncertainty. Subject to a set of aerodynamic and structural constraints, the uncertain response of the airfoil is optimized by means of both probability- and imprecise probability-based approaches. These solutions are compared with a reference airfoil optimized with a conventional design approach, in which the treatment of uncertainty is carried out in a simplistic fashion. Once evaluated in the probabilistic scenario, the airfoil designed with the conventional approach still achieves the largest aerodynamic efficiency mean. This airfoil is however affected by the largest performance sensitivity to NCRIT variations. The airfoils optimized by means of uncertainty-based approaches instead achieve larger performance robustness and reliability than the airfoil optimized with the conventional approach

Robust multi-fidelity design of a micro re-entry unmanned space vehicle

This article addresses the preliminary robust design of a small-scale re-entry unmanned space vehicle by means of a hybrid optimization technique. The approach, developed in this article, closely couples an evolutionary multi-objective algorithm with a direct transcription method for optimal control problems. The evolutionary part handles the shape parameters of the vehicle and the uncertain objective functions, while the direct transcription method generates an optimal control profile for the re-entry trajectory. Uncertainties on the aerodynamic forces and characteristics of the thermal protection material are incorporated into the vehicle model, and a Monte-Carlo sampling procedure is used to compute relevant statistical characteristics of the maximum heat flux and internal temperature. Then, the hybrid algorithm searches for geometries that minimize the mean value of the maximum heat flux, the mean value of the maximum internal temperature, and the weighted sum of their variance: the evolutionary part handles the shape parameters of the vehicle and the uncertain functions, while the direct transcription method generates the optimal control profile for the re-entry trajectory of each individual of the population. During the optimization process, artificial neural networks are utilized to approximate the aerodynamic forces required by the optimal control solver. The artificial neural networks are trained and updated by means of a multi-fidelity approach: initially a low-fidelity analytical model, fitted on a waverider type of vehicle, is used to train the neural networks, and through the evolution a mix of analytical and computational fluid dynamic, high-fidelity computations are used to update it. The data obtained by the high-fidelity model progressively become the main source of updates for the neural networks till, near the end of the optimization process, the influence of the data obtained by the analytical model is practically nullified. On the basis of preliminary results, the adopted technique is able to predict achievable performance of the small spacecraft and the requirements in terms of thermal protection materials

From risk-based health surveillance to health promotion: an evidence-based experience in a health care setting.

Health surveillance’s aim consists in different aspects: (i) to ensure worker’s health, (ii) to comply regulation, (iii) to detect health changes at their onset, (iv) to reduce cost, (v) to provide a fitness for job judgement, (vi) to provide a medical baseline and (vii) to be part of a preventive programme. Some of these aspects are perceived as benefits from the different stakeholders. Employers indicated as benefits worker’s satisfaction improvement, cost reduction, relationship improvement, early detection of health changes5. The study showed some other benefits: an improvement in worker’s satisfaction, an improvement in the relationship between stakeholders (even though based on qualitative data only), an early detection of health changes in few cases and a sickness absence reduction after influenza vaccination programme

Analysis of some global optimization algorithms for space trajectory design

In this paper, we analyze the performance of some global search algorithms on a number of space trajectory design problems. A rigorous testing procedure is introduced to measure the ability of an algorithm to identify the set of ²-optimal solutions. From the analysis of the test results, a novel algorithm is derived. The development of the novel algorithm starts from the redefinition of some evolutionary heuristics in the form of a discrete dynamical system. The convergence properties of this discrete dynamical system are used to derive a hybrid evolutionary algorithm that displays very good performance on the particular class of problems presented in this paper

Endoplasmic Reticulum Associated Aminopeptidase 2 (ERAP2) is released in the secretome of activated MDMs and reduces in vitro HIV-1 infection

Background: Haplotype-specific alternative splicing of the endoplasmic reticulum (ER) aminopeptidase type 2 (ERAP2) gene results in either full-length (FL, haplotype A) or alternatively spliced (AS, haplotype B) mRNA. HapA/HapA homozygous (HomoA) subjects show a reduced susceptibility to HIV-1 infection, probably secondary to the modulation of the antigen processing/presenting machinery. ERAP1 was recently shown to be secreted from the plasma membrane in response to activation; we investigated whether ERAP2 can be released as well and if the secreted form of this enzyme retains its antiviral function. Methods: Human monocyte derived macrophages (MDMs) were differentiated from peripheral blood mononuclear cells (PBMCs) isolated from 6 HomoA healthy controls and stimulated with IFN\u3b3 and LPS. ERAP2-FL secretion was evaluated by mass spectrometry. PBMCs (14 HomoA and 16 HomoB) and CD8-depleted PBMCs (CD8-PBMCs) (4 HomoA and 4 HomoB) were in vitro HIV-infected in the absence/presence of recombinant human ERAP2-FL (rhERAP2) protein; p24 viral antigen quantification was used to assess viral replication. IFN\u3b3 and CD69 mRNA expression, as well as the percentage of perforin-producing CD8+ T Lymphocytes, were analyzed 3 and 7-days post in vitro HIV-1-infection, respectively. The effect of rhERAP2 addition in cell cultures on T cell apoptosis, proliferation, activation, and maturation was evaluated as well on 24 h-stimulated PBMCs. Results: ERAP2 can be secreted from human MDMs in response to IFN\u3b3/LPS stimulation. Notably, the addition of rhERAP2 to PBMC and CD8-PBMC cultures resulted in the reduction of viral replication, though these differences were statistically significant only in PBMCs (p < 0.05 in both HomoA and HomoB). This protective effect was associated with an increase in IFN\u3b3 and CD69 mRNA expression and in the percentage of perforin-expressing CD107+CD8+ cells. RhERAP2 addition also resulted in an increase in CD8+ activated lymphocyte (CD25+HLA-DRII+) and Effector Memory/Terminally differentiated CD8+ T cells ratio. Conclusions: This is the first report providing evidence for the release of ERAP2 in the secretome of immunocompetent cells. Data herein also indicate that exogenous ERAP2-FL exerts its protective function against HIV-1 infection, even in HomoB subjects who do not genetically produce it. Presumably, this defensive extracellular feature is only partially dependent on immune system modulation

When food can make the difference : The case of elvitegravir-based co-formulation

Stribild should be administered under fed conditions to optimize drugs exposure. Here we assessed to what extent this advice is applied in the real life scenario by therapeutic drug monitoring in 75 HIV-infected patients given Stribild-based antiretroviral therapy. Fifty-three percent of our patients took Stribild at lunch/supper time, 23% in the morning with breakfast, and 24% middle in the morning or late in the evening. Twelve out of the 75 patients had unquantifiable elvitegravir concentrations, whereas in the remaining the levels were largely distributed. Wide inter-individual variability in the tenofovir, cobicistat and darunavir trough concentrations was also observed. In real life settings a significant proportion of patients took Stribild without food, namely in the mid-morning or late in the evening. This resulted in a wide inter-individual variability of antiretroviral drug trough concentrations. To avoid the risk for patients to experience suboptimal drug exposure, it is important that health professionals more convincingly advise their patients to take Stribild in fed conditions. On the other hand, the role of patient education and patient responsibility to correctly take the therapy should not be underestimated

Analytical Benchmark Problems for Multifidelity Optimization Methods

The paper presents a collection of analytical benchmark problems specifically selected to provide a set of stress tests for the assessment of multifidelity optimization methods. In addition, the paper discusses a comprehensive ensemble of metrics and criteria recommended for the rigorous and meaningful assessment of the performance of multifidelity strategies and algorithms

Valutazione dell'attività muscolare faringea attraverso elettromiografia di superficie nasofaringea in pazienti disfagici affetti da ictus ischemico acuto

La disfagia orofaringea è spesso presente durante la fase acuta di un ictus. Lo scopo di questo lavoro è stato quello di valutare se la registrazione elettromiografica di superficie tramite un elettrodo nasofaringeo può essere impiegata per testare l'attività muscolare del faringe nei pazienti con ictus acuto e se queste misurazioni elettrofisiologiche possono essere correlate con la valutazione clinica della deglutizione. Dal punto di vista clinico la severità del quadro è stata valutata mediante l'utilizzo della scala del National Institute of Health Stroke (NIHSS); la disfagia è stata valutata mediante il test di screening Gugging Swallowing Scale (GUSS); l'estensione della lesione ischemica alla TAC è stata misurata attraverso l'Alberta Stroke Programme Early CT Score (ASPECTS). Abbiamo valutato 70 pazienti di cui 50 disfagici (Dys+), e 20 non disfagici (Dys). Ciascun partecipante è stato sottoposto a un'elettromiografia di superficie registrata mediante un elettrodo NP costituito da un catetere di Teflon isolato in acciaio (lungo 16 cm e con un diametro in punta di 1,5 mm). L'elettrodo è stato inserito attraverso la cavità nasale, ruotato e posizionato approssimativamente 3 mm antero-inferiormente rispetto alla volta salpingo-palatina. Per ogni partecipante sono state registrate ed analizzate le risposte elettromiografiche di almeno quattro deglutizioni volontarie ripetute. La deglutizione induce sempre all'elettromiografia burst ripetitivi e polifasici di durata compresa fra 0,25 e 1 secondo, con un'ampiezza intorno ai 100-600mV. I disfagici hanno mostrano una maggiore durata del burst rilevato all'elettromiografia rispetto ai non disfagici, con una differenza statisticamente significativa (p < 0,001), ma non hanno mostrano differenze in termini di ampiezza del burst stesso (p = 0,775); quest'ultima invece era inversamente correlata con lo NIHSS score [r(48) = 0,31; p < 0,05)] e con lo ASPECTS score [r(48) = 0,27; p < 0,05]. Questi risultati suggeriscono che le registrazioni nasofaringee possono rappresentare un indice semi-quantitativo delle difficoltà deglutitorie secondarie a disfunzione faringea ed in particolare, i risultati dell'elettromiografia sarebbero indicativi di una ridotta motilità faringea durante la fase acuta di un ictus