1,721,097 research outputs found
A Novel Co-simulation Framework for Verification and Validation of GNC Algorithms for Autonomous UAV
No full textThe use of autonomous Unmanned Aerial Vehicles (UAVs) in commercial applications has the potential to disrupt several industries. To effectively cover the broad spectrum of possible applications, UAV integrators require the ability to develop drone platforms that meet the requirements specified for the missions to accomplish. This is not limited to the correct sizing of the UAV physical subsystems, but also on the Guidance, Navigation, and Control (GNC) algorithms that enable the UAV to operate autonomously in an efficient way. System simulation can provide a valuable support to both activities. In the predesign phase, it allows exploring the design space, analyzing the performance of multiple UAV variants, and selecting the most promising concepts. Once this phase is completed, the resulting dynamic and multi-physics performance model of the UAV presents a sufficient fidelity to support the continuous development of GNC algorithms. Thanks to a novel co-simulation framework proposed in this paper, the performance model can then be integrated in a co-simulation framework to include perception sensors, mission environment, and GNC algorithms. Two use cases based on the framework are presented and discussed
Quadrotor Trajectory Control Based on Energy-Optimal Reference Generator
Full text linkInspired by the limited battery life of multi-rotor unmanned aerial vehicles (UAVs), this research investigated hierarchical real-time control of UAVs with the generation of energy-optimal reference trajectories. The goal was to design a reference generator and controller based on optimal-control theory that would guarantee energy consumption close to optimal with lower computational cost. First, a least-squares-estimation-(LSE) algorithm identified the parameters of the UAV mathematical model. Then, by considering a precise electrical model for the brushless DC motors and rest-to-rest maneuvers, the extraction of clear rules to compute the optimal mission time and generate ’energetic trajectories’ was performed. These rules emerged from analyzing the optimal-control strategy results that minimized the consumption over many simulations. Afterward, a hierarchical controller tracked those desired energetic trajectories identified as sub-optimal. Numerical experiments compared the results regarding trajectory tracking, energy performance index, and battery state of charge (SOC). A co-simulation framework consisting of commercial software tools, Simcenter Amesim for the physical modeling of the UAV, and Matlab-Simulink executed numerical simulations of the implemented controller
ANALYSIS OF PFS AND OS FROM THE SATURN STUDY ACCORDING TO EGFR IHC STATUS USING THE H-SCORE READING METHOD
No full textPerspectives on salvage therapy for non-small-cell lung cancer
No full text: Platinum-based chemotherapy offers a modest survival advantage over best supportive care in chemotherapy-naive patients with a good performance status and advanced/metastatic non-small-cell lung cancer (NSCLC). Despite the survival benefit associated with first-line chemotherapy, the majority of patients will experience relapse or disease progression. In clinicalpractice, an increasing number of patients maintain a good performance status after first-line treatment and are eligible for further treatments. Docetaxel (Taxotere) at 75 mg/m2 given once every 3 weeks has been the standard of care for second-line chemotherapy since the year 2000. Pemetrexed (Alimta) is a novel multitargeted antifolate agent with single-agent activity in first- and second-line treatment of NSCLC. A large phase 111 study comparing docetaxel to pemetrexed in second-line therapy demonstrated that pemetrexed is equally active and less toxic than docetaxel. Based on these results, pemetrexed is a reasonable second-line chemotherapy option for patients with recurrent, advanced NSCLC. Progress made in the field of molecular biology has led to the identification of drugs active against specific cellular targets. Gefitinib (Iressa) and erlotinib (Tarceva) are both orally active tyrosine kinase inhibitors of the epidermal growth factor receptor. Phase II and III trials have demonstrated that these agents are active particularly in a subgroup of patients with specific biologic characteristics. Both drugs have been approved for the treatment of pretreated NSCLC. Other drugs, such as cetuximab (Erbitux) and bevacizumab (Avastin) have shown promising activity in NSCLC and are currently being tested in clinical trials
Evaluation of EGFR protein expression by immunohistochemistry using H-score and the magnification rule: Re-analysis of the SATURN study
No full textAbstractIntroductionThe phase III SATURN study demonstrated that first-line maintenance erlotinib extended progression-free survival (PFS) and overall survival (OS) versus placebo in patients with advanced non-small cell lung cancer (NSCLC). Analysis of epidermal growth factor receptor (EGFR) expression by immunohistochemistry (IHC) found no significant interaction between EGFR IHC status and PFS (p=0.63) or OS (p=0.52). The FLEX study of first-line cetuximab plus chemotherapy demonstrated that EGFR IHC expression was predictive of improved OS with cetuximab when assessed by H-score with a magnification rule. This novel method was used to reassess samples from SATURN.MethodsThe H-score method assigned a score of 0–300 to each patient, based on the percentage of cells stained at different intensities viewed at various magnifications. The discriminatory threshold was set at 200, per the FLEX study, and existing samples were re-read and classed as low (H-score<200) or high (≥200) EGFR expression. PFS and OS were re-analyzed based on these new classifications.ResultsIn the overall and EGFR wild-type populations, erlotinib provided a consistent survival benefit versus placebo. Hazard ratios (HRs) in the overall population were similar between EGFR IHC-positive and -negative patients for median PFS (HR 0.68 [95% confidence interval (CI) 0.53–0.86] and 0.76 [95% CI 0.62–0.93], respectively) and OS (HR 0.80 [95% CI 0.62–1.05] and 0.80 [95% CI 0.64–1.01] for IHC-positive and IHC-negative, respectively). In the EGFR wild-type population, HRs were again similar between EGFR IHC-positive and -negative subpopulations for PFS (HR 0.69 [95% CI 0.51–0.95] and 0.84 [95% CI 0.63–1.12], respectively) and OS (HR 0.78 [95% CI 0.55–1.10] and 0.76 [95% CI 0.55–1.05], respectively).ConclusionsThese data suggest that EGFR IHC does not have value as a marker to predict erlotinib benefit in the first-line maintenance setting for advanced NSCLC
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Neoadjuvant immunotherapy strategies for resectable non-small cell lung cancer (NSCLC): Current evidence among special populations and future perspectives
No full textAbout one third of patients with Non-Small Cell Lung Cancer (NSCLC) presents at diagnosis with localized or locally advanced disease amenable to curative surgical resection. Surgical operability refers to stage Ito IIIA and selected stage IIIB NSCLC. One of the main challenges in the management of early-stage resectable NSCLC is the optimization of available therapeutic strategies to prevent local and distant disease relapse, thus improving survival outcomes. There is evidence supporting the clinical use of both adjuvant and neoadjuvant immunotherapy-based strategies for resected/resectable, stage IB-IIIA NSCLC. Available data from randomized phase III trials have led to the incorporation of several immune checkpoint blockers (ICBs) into the international guidelines for early-stage NSCLC. Preclinical rationale of targeting specific subsets of T-cells by acting early on immune checkpoint receptors (e.g., PD-(L)1 and CTLA-4) is strong. Recent evidence is in favor of the neoadjuvant approach alone or as a part of perioperative strategy, demonstrating survival benefit. Combining neoadjuvant chemotherapy and immunotherapy before surgery results in both pathologic complete response (pCR) and major pathologic response (MPR) improvement, and survival outcomes, with no major safety issues. In this review, we summarize the rationale behind neoadjuvant/perioperative immunotherapy strategies and, due to the clinical relevance of immunotherapy in resectable NSCLC, we provide current evidence of this cutting-edge approach among special populations including older adults, women, and oncogene addicted NSCLC. To conclude, we present future perspectives in the use of immunotherapy for operable NSCLC with a special focus on novel investigational combinations underway
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