Optimal low-thrust trajectories to asteroids through an algorithm based on differential dynamic programming

In this paper an optimisation algorithm based on Differential Dynamic Programming is applied to the design of rendezvous and fly-by trajectories to near Earth objects. Differential dynamic programming is a successive approximation technique that computes a feedback control law in correspondence of a fixed number of decision times. In this way the high dimensional problem characteristic of low-thrust optimisation is reduced into a series of small dimensional problems. The proposed method exploits the stage-wise approach to incorporate an adaptive refinement of the discretisation mesh within the optimisation process. A particular interpolation technique was used to preserve the feedback nature of the control law, thus improving robustness against some approximation errors introduced during the adaptation process. The algorithm implements global variations of the control law, which ensure a further increase in robustness. The results presented show how the proposed approach is capable of fully exploiting the multi-body dynamics of the problem; in fact, in one of the study cases, a fly-by of the Earth is scheduled, which was not included in the first guess solution

Research in Extracorporeal Life Support: A Call to Action

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Prone position for acute respiratory distress syndrome : A systematic review and meta-analysis

Rationale: The application of prone positioning for acute respiratory distress syndrome (ARDS) has evolved, with recent trials focusing on patients with more severe ARDS, and applying prone ventilation for more prolonged periods. Objectives: This review evaluates the effect of prone positioning on 28-day mortality (primary outcome) compared with conventional mechanical ventilation in the supine position for adults with ARDS. Methods: We updated the literature search from a systematic review published in 2010, searching MEDLINE, EMBASE, and CENTRAL (through to August 2016). We included randomized, controlled trials (RCTs) comparing prone to supine positioning in mechanically ventilated adults with ARDS, and conducted sensitivity analyses to explore the effects of duration of prone ventilation, concurrent lung-protective ventilation and ARDS severity. Secondary outcomes included Pa-O2/FIO2 ratio on Day 4 and an evaluation of adverse events. Meta-analyses used random effects models. Methodologic quality of the RCTs was evaluated using the Cochrane risk of bias instrument, and methodologic quality of the overall body of evidence was evaluated using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) guidelines. Results: Eight RCTs fulfilled entry criteria, and included 2,129 patients (1,093 [51%] proned). Meta-analysis revealed no difference in mortality (risk ratio [RR], 0.84; 95% confidence interval [CI], 0.68-1.04), but subgroup analyses found lower mortality with 12 hours or greater duration prone (five trials; RR, 0.74; 95% CI, 0.56-0.99) and for patients with moderate to severe ARDS (five trials; RR, 0.74; 95% CI, 0.56-0.99). Pa-O2/FIO2 ratio on Day 4 for all patients was significantly higher in the prone positioning group (mean difference, 23.5; 95% CI, 12.4-34.5). Prone positioning was associated with higher rates of endotracheal tube obstruction and pressure sores. Risk of bias was low across the trials. Conclusions: Prone positioning is likely to reduce mortality among patients with severe ARDS when applied for at least 12 hours daily

Measurement of the Atmospheric Muon Spectrum from 20 to 3000 GeV

The absolute muon flux between 20 GeV and 3000 GeV is measured with the L3 magnetic muon spectrometer for zenith angles ranging from 0 degree to 58 degree. Due to the large exposure of about 150 m2 sr d, and the excellent momentum resolution of the L3 muon chambers, a precision of 2.3 % at 150 GeV in the vertical direction is achieved. The ratio of positive to negative muons is studied between 20 GeV and 500 GeV, and the average vertical muon charge ratio is found to be 1.285 +- 0.003 (stat.) +- 0.019 (syst.).Comment: Total 32 pages, 9Figure

Efficacy and adverse events of early high-frequency oscillatory ventilation in adult burn patients with acute respiratory distress syndrome

Background: High-frequency oscillatory ventilation (HFOV) is one of lung protective strategies in acute respiratory distress syndrome (ARDS). It is not recommended to be used as initial mode of ventilation. Previous studies showed conflicting results for late use of HFOV (after prolonged period of conventional mechanical ventilation (CMV)). This study investigated the use of HFOV as an early therapy (after 24 h of CMV) in the management of ARDS due to burn. Methods: 70 burned ARDS patients were ventilated by CMV during the first 24 h (Day 0). Then, patients were randomly allocated into two equal groups (35 each): Group 1 (G 1 or CMV): they continued on CMV. Group 2 (G2 or HFOV): HFOV was instituted for 72 h (Days 1, 2, 3). Then, patients were shifted to CMV on Day 4 to continue on CMV. Ventilator settings, gas exchange parameters, hemodynamics, sedatives, vasoactive and paralytic requirements, barotraumas and hospital mortality were recorded and compared between the two groups. Results: In Day 0: Demographic data, ventilator settings, gas exchange parameters, and hemodynamics showed no significant difference between both groups. Days 1, 2, 3: there was statistically significant decrease of FiO2 and OI accompanied by an increase in PaO2, PaO2/FiO2 and PaCO2 in G2. Day 4: while both groups on CMV, G2 patients showed statistically significant decrease in PEEP and mPaw with same gas exchange findings on Days 1, 2, 3 between two groups. During the study period, Hypotension was observed following HFOV in G2 and was most significant in Day 1. G2 showed statistically significant increase in barotraumas and required more midazolam, atracurium and norepinephrine. There was no statistically significant difference in 30 days mortality between both groups. Conclusions: Early HFOV therapy is effective in improving oxygenation in burn patients with ARDS, but it failed to reduce hospital mortality

gp100/pmel17 and tyrosinase encode multiple epitopes recognized by Th1-type CD4+T cells.

CD4(+) T cells modulate the magnitude and durability of CTL responses in vivo, and may serve as effector cells in the tumour microenvironment. In order to identify the turnout epitopes recognized by tumour-reactive human CD4+ T cells, we combined the use of an HLA-DR4/peptide binding algorithm with an IFN-gamma ELISPOT assay. Two known and three novel CD4+ T cell epitopes derived from the gp 100/pmel17 and tyrosinase mefanocyte-associated antigens were confirmed or identified. Of major interest, we determined that freshly-isolated PBMC frequencies of Th1-type CD4+ T recognizing these peptides are frequently elevated in HLA-DR4+ melanoma patients (but not normal donors) that are currently disease-free as a result of therapeutic intervention. Epitope-specific CD4+ T cells from normal DR4+ donors could be induced, however, after in vitro stimulation with autologous dendritic cell pulsed with antigens (peptides or antigen-positive melanoma lysates) or infected with recombinant vaccinia virus encoding the relevant antigen. Peptide-reactive CD4+ T cells also recognized HLA-DR4+ melanoma cell lines that constitutively express the relevant antigen. Based on these data, these epitopes may serve as potent vaccine components to promote clinically-relevant Th1-type CD4+ T cell effector function in situ. (C) 2001 Cancer Research Campaign

Mechanical ventilation in adults with acute respiratory distress syndrome: An official clinical guideline of American Thoracic Society/European Society of Intensive Care medicine/Society of Critical care medicine

The aim of this guideline is to provide clinical recommendation on the use of mechanical ventilation in adult patients with acute respiratory distress syndrome (ARDS). Methods. This guideline is based on systematic review and metaanalysis of available literature on the use of mechanical ventilation in adult patients with ARDS. Results. All patients with ARDS should be mechanically ventilated with the use of lower tidal volumes (4\u20138 ml/kg predicted bodyweight) and lower inspiratory pressures (plateau pressure, 30 cm H2O). In severe ARDS, the prone positioning for more than 12 h/d is strongly recommended. In patients with moderate to severe ARDS, routine use of high-frequency oscillatory ventilation is not recommended; conditional recommendation has been developed for the use of higher positive end-expiratory pressure and recruitment maneuvers. Cu?? \u2013 ently, there is not enough evidence for the use of extracorporeal membrane oxygenation in patients with severe ARDS. Conclusions. Practical recommendations on selected methods to co?? \u2013 ect ventilation disturbances in adult patients with ARDS have been developed. Clinicians involved in the management of patients with ARDS should use personalized approach to the treatment of these patients. Key words: acute respiratory distress syndrome, adults, mechanical ventilation, guideline, end-expiratory pressure, tidal volume, inspiratory pressure, extracorporeal membrane oxygenation. \ua9 2018 National Research University Higher School of Economics. All rights reserved

An official American Thoracic Society/European Society of intensive care medicine/society of critical care medicine clinical practice guideline : mechanical ventilation in adult patients with acute respiratory distress syndrome

Background: This document provides evidence-based clinical practice guidelines on the use of mechanical ventilation in adult patients with acute respiratory distress syndrome (ARDS). Methods: A multidisciplinary panel conducted systematic reviews and metaanalyses of the relevant research and applied Grading of Recommendations, Assessment, Development, and Evaluation methodology for clinical recommendations. Results: For all patients with ARDS, the recommendation is strong for mechanical ventilation using lower tidal volumes (4-8 ml/kg predicted body weight) and lower inspiratory pressures (plateau pressure < 30 cm H2O) (moderate confidence in effect estimates). For patients with severe ARDS, the recommendation is strong for prone positioning for more than 12 h/d (moderate confidence in effect estimates). For patients with moderate or severe ARDS, the recommendation is strong against routine use of high-frequency oscillatory ventilation (high confidence in effect estimates) and conditional for higher positive end-expiratory pressure (moderate confidence in effect estimates) and recruitment maneuvers (low confidence in effect estimates). Additional evidence is necessary to make a definitive recommendation for or against the use of extracorporeal membrane oxygenation in patients with severe ARDS. Conclusions: The panel formulated and provided the rationale for recommendations on selected ventilatory interventions for adult patients with ARDS. Clinicians managing patients with ARDS should personalize decisions for their patients, particularly regarding the conditional recommendations in this guideline