UAV Formation Flight Utilizing a Low Cost, Open Source Configuration

The control of multiple unmanned aerial vehicles (UAVs) in a swarm or cooperative team scenario has been a topic of great interest for well over a decade, growing steadily with the advancements in UAV technologies. In the academic community, a majority of the studies conducted rely on simulation to test developed control strategies, with only a few institutions known to have nurtured the infrastructure required to propel multiple UAV control studies beyond simulation and into experimental testing. With the Cal Poly UAV FLOC Project, such an infrastructure was created, paving the way for future experimentation with multiple UAV control systems. The control system architecture presented was built on concepts developed in previous work by Cal Poly faculty and graduate students. An outer-loop formation flight controller based on a virtual waypoint implementation of potential function guidance was developed for use on an embedded microcontroller. A commercially-available autopilot system, designed for fully autonomous waypoint navigation utilizing low cost hardware and open source software, was modified to include the formation flight controller and an inter-UAV communication network. A hardware-in-the-loop (HIL) simulation was set up for multiple UAV testing and was utilized to verify the functionality of the modified autopilot system. HIL simulation results demonstrated leader-follower formation convergence to 15 meters as well as formation flight with three UAVs. Several sets of flight tests were conducted, demonstrating a successful leader-follower formation, but with relative distance convergence only reaching a steady state value of approximately 35 +/- 5 meters away from the leader

Vasoreactivity in CADASIL: comparison to structural MRI and neuropsychology

Impaired cerebrovascular reactivity precedes histological and clinical evidence of CADASIL in animal models. We aimed to more fully characterise peripheral and cerebral vascular function and reactivity in a cohort of adult CADASIL patients, and explore the associations of these with conventional clinical, imaging and neuropsychological measures. 22 adults with CADASIL gave informed consent to participate in an exploratorystudy of vascular function in CADASIL. Clinical assessment, comprehensive vascular assessment, MRI and neuropsychological testing were conducted. Transcranial Doppler and arterial spin labelling MRI with hypercapnia challenge both measured cerebral vasoreactivity. Number and volume of lacunes, subcortical hyperintensity volume, microbleeds and normalised brain volume were assessed on MRI scans. Analysis was exploratory and examined associations between different markers. The results showed that cerebrovascular reactivity measured by ASL correlated with peripheral vasoreactivity measured by flow mediated dilatation. Subjects with >5 lacunes were older, with evidence of atherosclerosis and had impaired cerebral and peripheral vasoreactivity. Subjects with depressive symptoms, disability or delayed processing speed, also had impaired vasoreactivity, as well as more lacunes and brain atrophy. Impaired vasoreactivity and vascular dysfunction may play a significant role in the pathophysiology of CADASIL and vascular tests may be important to include in both longitudinal and clinical trials

Regioselective generation and reactivity control of subnanometric platinum clusters in zeolites for high-temperature catalysis

[EN] Subnanometric metal species (single atoms and clusters) have been demonstrated to be unique compared with their nanoparticulate counterparts. However, the poor stabilization of subnanometric metal species towards sintering at high temperature (>500 degrees C) under oxidative or reductive reaction conditions limits their catalytic application. Zeolites can serve as an ideal support to stabilize subnanometric metal catalysts, but it is challenging to localize subnanometric metal species on specific sites and modulate their reactivity. We have achieved a very high preference for localization of highly stable subnanometric Pt and PtSn clusters in the sinusoidal channels of purely siliceous MFI zeolite, as revealed by atomically resolved electron microscopy combining high-angle annular dark-field and integrated differential phase contrast imaging techniques. These catalysts show very high stability, selectivity and activity for the industrially important dehydrogenation of propane to form propylene. This stabilization strategy could be extended to other crystalline porous materials.This work has been supported by the European Union through the European Research Council (grant ERC-AdG-2014-671093, SynCatMatch) and the Spanish government through the Severo Ochoa Programme (SEV-2016-0683). L.L. thanks ITQ for providing a contract. The authors also thank the Microscopy Service of UPV for the TEM and STEM measurements. The XAS measurements were carried out in CLAESS beamline at the ALBA synchrotron. HR STEM measurements were performed at DME-UCA in Cadiz University with financial support from FEDER/MINECO (MAT2017-87579-R and MAT2016-81118-P). A relevant patent application (European patent application No. 19382024.8) has been presented. C.W.L. thanks CAPES (Science without Frontiers-Process no. 13191/13-6) for a predoctoral fellowship.Liu, L.; Lopez-Haro, M.; Lopes, CW.; Li, C.; Concepción Heydorn, P.; Simonelli, L.; Calvino, JJ.... (2019). Regioselective generation and reactivity control of subnanometric platinum clusters in zeolites for high-temperature catalysis. Nature Materials. 18(8):866-875. https://doi.org/10.1038/s41563-019-0412-6S86687518

Individual participant data analysis of two trials on aldosterone blockade in myocardial infarction

Background: Two recent randomised trials studied the benefit of mineralocorticoid receptor antagonists (MRAs) in ST-segment elevation myocardial infarction (STEMI) irrespective or in absence of heart failure. The studies were both undersized to assess hard clinical endpoints. A pooled analysis was preplanned by the steering committees. Methods: We conducted a prespecified meta-analysis of patient-level data of patients with STEMI recruited in two multicentre superiority trials, randomised within 72 hours after symptom onset. Patients were allocated (1:1) to two MRA regimens: (1) an intravenous bolus of potassium canrenoate (200 mg) followed by oral spironolactone (25 mg once daily) versus standard therapy or (2) oral eplerenone (25–50 mg) versus placebo. The primary and key secondary outcomes, all-cause death and the composite of all-cause death or resuscitated sudden death, respectively, were assessed in the intention-to-treat population using a Cox model stratified on the study identifier. Results: Patients were randomly assigned to receive (n=1118) or not the MRA regimen (n=1123). After a median follow-up time of 188 days, the primary and secondary outcomes occurred in 5 (0.4%) and 17 (1.5%) patients (adjusted HR (adjHR) 0.31, 95% CI 0.11 to 0.86, p=0.03) and 6 (0.5%) and 22 (2%) patients (adjHR 0.26, 95% CI 0.10 to 0.65, p=0.004) in the MRA and control groups, respectively. There were also trends towards lower rates of cardiovascular death (p=0.06) and ventricular fibrillation (p=0.08) in the MRA group. Conclusion: Our analysis suggests that compared with standard therapy, MRA regimens are associated with a reduction of death and death or resuscitated sudden death in STEMI

Oxygen challenge magnetic resonance imaging in healthy human volunteers

Oxygen challenge imaging involves transient hyperoxia applied during deoxyhaemoglobin sensitive (T2*-weighted) magnetic resonance imaging and has the potential to detect changes in brain oxygen extraction. In order to develop optimal practical protocols for oxygen challenge imaging, we investigated the influence of oxygen concentration, cerebral blood flow change, pattern of oxygen administration and field strength on T2*-weighted signal. Eight healthy volunteers underwent multi-parametric magnetic resonance imaging including oxygen challenge imaging and arterial spin labelling using two oxygen concentrations (target FiO2 of 100 and 60%) administered consecutively (two-stage challenge) at both 1.5T and 3T. There was a greater signal increase in grey matter compared to white matter during oxygen challenge (p < 0.002 at 3T, P < 0.0001 at 1.5T) and at FiO2 = 100% compared to FiO2 = 60% in grey matter at both field strengths (p < 0.02) and in white matter at 3T only (p = 0.0314). Differences in the magnitude of signal change between 1.5T and 3T did not reach statistical significance. Reduction of T2*-weighted signal to below baseline, after hyperoxia withdrawal, confounded interpretation of two-stage oxygen challenge imaging. Reductions in cerebral blood flow did not obscure the T2*-weighted signal increases. In conclusion, the optimal protocol for further study should utilise target FiO2 = 100% during a single oxygen challenge. Imaging at both 1.5T and 3T is clinically feasible

Demographic trade-offs predict tropical forest dynamics

Understanding tropical forest dynamics and planning for their sustainable management require efficient, yet accurate, predictions of the joint dynamics of hundreds of tree species. With increasing information on tropical tree life histories, our predictive understanding is no longer limited by species data but by the ability of existing models to make use of it. Using a demographic forest model, we show that the basal area and compositional changes during forest succession in a neotropical forest can be accurately predicted by representing tropical tree diversity (hundreds of species) with only five functional groups spanning two essential trade-offs—the growth-survival and stature-recruitment trade-offs. This data-driven modeling framework substantially improves our ability to predict consequences of anthropogenic impacts on tropical forests

Structural modulation and direct measurement of subnanometric bimetallic PtSn clusters confined in zeolites

[EN] Modulating the structures of subnanometric metal clusters at the atomic level is a great synthetic and characterization challenge in catalysis. Here, we show how the catalytic properties of subnanometric platinum clusters (0.5-0.6 nm) confined in the sinusoidal 10R channels of purely siliceous MFI zeolite are modulated upon introduction of partially reduced tin species that interact with the noble metal at the metal/support interface. The platinum-tin clusters are stable in H(2)over an extended period of time (>6 h), even at high temperatures (for example, 600 degrees C), which is determined by only a few additional tin atoms added to the platinum clusters. The structural features of platinum-tin clusters, which are not immediately visible by conventional characterization techniques but can be established after combination of in situ extended X-ray absorption fine structure, high-angle annular dark-field scanning transmission electron microscopy and CO infrared data, are key to providing a one-order of magnitude lower deactivation rate in the propane dehydrogenation reaction while maintaining high intrinsic (initial) catalytic activityThis work was supported by the European Union through the European Research Council (grant ERC-AdG-2014-671093, SynCatMatch) and the Spanish government through the "Severo Ochoa Program" (SEV-2016-0683). L.L. thanks the ITQ for providing a contract. The authors also thank the Microscopy Service of the UPV for the TEM and STEM measurements. The XAS measurements were carried out in the CLAESS beamline of the ALBA synchrotron. We thank Giovanni Agostini for his kind support in the analysis of XAS data. HR-HAADF-STEM measurements were performed at DME-UCA at Cadiz University with financial support from FEDER/MINECO (MAT2017-87579-R and MAT2016-81118-P). C.W.L. thanks CAPES (Science without Frontiers -Process no. 13191/13-6) for a predoctoral fellowship. The financial support from ExxonMobil for this project is also greatly acknowledged.Liu, L.; Lopez-Haro, M.; Lopes, CW.; Rojas-Buzo, S.; Concepción Heydorn, P.; Manzorro, R.; Simonelli, L.... (2020). Structural modulation and direct measurement of subnanometric bimetallic PtSn clusters confined in zeolites. Nature Catalysis. 3(8):628-638. https://doi.org/10.1038/s41929-020-0472-7S62863838Liu, L. & Corma, A. Metal catalysts for heterogeneous catalysis: from single atoms to nanoclusters and nanoparticles. Chem. Rev. 118, 4981–5079 (2018).An, K. & Somorjai, G. A. Nanocatalysis I: synthesis of metal and bimetallic nanoparticles and porous oxides and their catalytic reaction studies. Catal. 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Brain imaging factors associated with progression of subcortical hyperintensities in CADASIL over two year follow up

Background: Mutations in the NOTCH3 gene cause CADASIL, a cerebral small vessel disease manifesting with stroke, migraine and dementia in adults. The disease displays significant phenotypic variability which is incompletely explained. Early abnormalities in vascular function have been shown in animal models. We postulated that studying changes in vascular function may offer insights into disease progression. Methods: Twenty two subjects with CADASIL (50% female, 50 (±11) years) from 19 pedigrees were included in a longitudinal multimodality study using brain MRI, clinical measures, neuropsychology, and measures of peripheral vascular function. MRI studies included measurement of structural brain changes, cerebral blood flow (CBF) and cerebrovascular reactivity by arterial spin labelling and a CO2 respiratory challenge. Results: Over two years, new stroke or TIA occurred in 5 (23%) subjects and new significant disability in 1 (5%). There were significant increases in number of lacunes, subcortical hyperintensity volume and microbleeds, and a decrease in brain volume. CBF declined by 3.2 (±4.5) ml/100g/min over two years. CBF and carotid‐femoral pulse wave velocity at baseline predicted change in subcortical hyperintensity volume at follow up. Carotid‐intima‐media thickness and age predicted brain atrophy. Baseline CBF was lower in subjects who showed a decline in attention and working memory. Conclusion: CBF predicts radiological progression of hyperintensities and thus is a potential biomarker of disease progression in CADASIL. Over two years, there were changes in several relevant imaging biomarkers (CBF, brain volume, lacunes, microbleeds, and hyperintensity volume). Future studies in CADASIL should consider assessment of CBF as prognostic factor

High platelet reactivity in patients with acute coronary syndromes undergoing percutaneous coronary intervention: Randomised controlled trial comparing prasugrel and clopidogrel

Background: Prasugrel is more effective than clopidogrel in reducing platelet aggregation in acute coronary syndromes. Data available on prasugrel reloading in clopidogrel treated patients with high residual platelet reactivity (HRPR) i.e. poor responders, is limited. Objectives: To determine the effects of prasugrel loading on platelet function in patients on clopidogrel and high platelet reactivity undergoing percutaneous coronary intervention for acute coronary syndrome (ACS). Patients: Patients with ACS on clopidogrel who were scheduled for PCI found to have a platelet reactivity ≥40 AUC with the Multiplate Analyzer, i.e. “poor responders” were randomised to prasugrel (60 mg loading and 10 mg maintenance dose) or clopidogrel (600 mg reloading and 150 mg maintenance dose). The primary outcome measure was proportion of patients with platelet reactivity <40 AUC 4 hours after loading with study medication, and also at one hour (secondary outcome). 44 patients were enrolled and the study was terminated early as clopidogrel use decreased sharply due to introduction of newer P2Y12 inhibitors. Results: At 4 hours after study medication 100% of patients treated with prasugrel compared to 91% of those treated with clopidogrel had platelet reactivity <40 AUC (p = 0.49), while at 1 hour the proportions were 95% and 64% respectively (p = 0.02). Mean platelet reactivity at 4 and 1 hours after study medication in prasugrel and clopidogrel groups respectively were 12 versus 22 (p = 0.005) and 19 versus 34 (p = 0.01) respectively. Conclusions: Routine platelet function testing identifies patients with high residual platelet reactivity (“poor responders”) on clopidogrel. A strategy of prasugrel rather than clopidogrel reloading results in earlier and more sustained suppression of platelet reactivity. Future trials need to identify if this translates into clinical benefit

Effect of eplerenone on extracellular cardiac matrix biomarkers in patients with acute ST-elevation myocardial infarction without heart failure: insights from the randomized double-blind REMINDER Study

Objective: Aldosterone stimulates cardiac collagen synthesis. Circulating biomarkers of collagen turnover provide a useful tool for the assessment of cardiac remodeling in patients with an acute myocardial infarction (MI).  Methods: The REMINDER trial assessed the effect of eplerenone in patients with an acute ST-elevation Myocardial Infarction (STEMI) without known heart failure (HF), when initiated within 24 h of symptom onset. The primary outcome was almost totally (>90%) driven by natriuretic peptide (NP) thresholds after 1-month post-MI (it also included a composite of cardiovascular death or re-hospitalization or new onset HF or sustained ventricular tachycardia or fibrillation or LVEF ≤40% after 1-month post-MI). This secondary analysis aims to assess the extracellular matrix marker (ECMM) levels with regards to: (1) patients` characteristics; (2) determinants; (3) and eplerenone effect.  Results: Serum levels of ECMM were measured in 526 (52%) of the 1012 patients enrolled in the REMINDER trial. Patients with procollagen type III N-terminal propeptide (PIIINP) above the median were older and had worse renal function (p < 0.05). Worse renal function was associated with increased levels of PIIINP (standardized β ≈ 0.20, p < 0.05). Eplerenone reduced PIIINP when the levels of this biomarker were above the median of 3.9 ng/mL (0.13 ± 1.48 vs. -0.37 ± 1.56 ng/mL, p = 0.008). Higher levels of PIIINP were independently associated with higher proportion of NP above the prespecified thresholds (HR = 1.95, 95% CI 1.16-3.29, p = 0.012).  Conclusions: Eplerenone effectively reduces PIIINP levels when baseline values were above the median. Eplerenone may limit ECMM formation in post-MI without HF