Experimental Investigation into the Aerodynamic Performance of Both Rigid and Flexible Wing Structured Micro-Air-Vehicles

The Air Force Research Lab, Munitions Directorate, Eglin Air Force Base, Florida has designed a man-portable carbon-fiber Micro-Air-Vehicle (MA V) used for on-the-spot surveillance by Special Operations Forces (SOF) for enemy reconnaissance as well as post-strike Battle Damage Assessment (BDA).The main goals of this experiment are: 1) characterize the flow quality of the new AFIT 3\u27 x 3\u27 wind tunnel and 2) determine the aerodynamic performance characteristics of the 24 span, 6 chord flexible and rigid wing MA V s. The turbulent intensity of the wind tunnel was approximately 2%. Both MA Vs had an average lift slope within 3.5% of the theoretical value. Flexible wings deformed in response to perturbations in local flow field conditions, promulgating the delay of wing stall by nearly double. Aeroelastic effects begin to dominate low speed, laminar Reynolds number effects at tunnel velocities greater than 30 miles per hour. The flexible wing MA V displayed static stability in all three principal control axes (Pitch, Roll, Yaw), while the rigid MA V was not definitively stable in any axis. All flexible wing control surface configurations resulted in predictable and consistent performance between -10° and + 10° elevon deflection. Reponses declined steadily after ±10° showing dramatic direction changes

An Experimental Investigation into the Effect of Flap Angles for a Piezo-Driven Wing

This article presents a comparison of results from six degree of freedom force and moment measurements and Particle Image Velocimetry (PIV) data taken on the Air Force Institute of Technology\u27s (AFIT) piezoelectrically actuated, biomimetically designed Hawkmoth, Manduca Sexta, class engineered wing, at varying amplitudes and flapping frequencies, for both trimmed and asymmetric flapping conditions to assess control moment changes. To preserve test specimen integrity, the wing was driven at a voltage amplitude 50% below the maximum necessary to achieve the maximal Hawkmoth total stroke angle. 86 and 65 stroke angles were achieved for the trimmed and asymmetric tests respectively. Flapping tests were performed at system structural resonance, and at 10% off system resonance at a single amplitude, and PZT power consumption was calculated for each test condition. Two-dimensional PIV visualization measurements were taken transverse to the wing planform, recorded at the mid-span, for a single frequency and amplitude setting, for both trimmed and asymmetric flapping to correlate with the 6-DoF balance data. Linear velocity data was extracted from the 2-D PIV imagery at 1/2 and 1 chord locations above and below the wing, and the mean velocities were calculated for four separate wing phases during the flap cycle. The mean forces developed during a flap cycle were approximated using a modification of the Rankine-Froude axial actuator disk model to calculate the transport of momentum flux as a measure of vertical thrust produced during a static hover flight condition. Values of vertical force calculated from the 2-D PIV measurements were within 20% of the 6-DOF force balance experiments. Power calculations confirmed flapping at system resonance required less power than at off resonance frequencies, which is a critical finding necessary for future vehicle design considerations

Investigation into Reynolds Number Effects on a Biomimetic Flapping Wing

This research investigated the behavior of a Manduca sexta inspired biomimetic wing as a function of Reynolds number by measuring the aerodynamic forces produced by varying the characteristic wing length and testing at air densities from atmospheric to near vacuum. A six degree of freedom balance was used to measure forces and moments, while high speed cameras were used to measure wing stroke angle. An in-house created graphical user interface was used to vary the voltage of the drive signal sent to the piezoelectric actuator which determined the wing stroke angle. The Air Force Institute of Technology baseline 50 mm wing was compared to wings manufactured with 55, 60, 65, and 70 mm spans, while maintaining a constant aspect ratio. Tests were conducted in a vacuum chamber at air densities between 0.5% and 100% of atmospheric pressure. Increasing the wingspan increased the wing’s weight, which reduced the first natural frequency; and did not result in an increase in vertical force over the baseline 50 mm wing. However, if the decrease in natural frequency corresponding to the increased wing span was counteracted by increasing the thickness of the joint material in the linkage mechanism, vertical force production increased over the baseline wing planform. Of the wings built with the more robust flapping mechanism, the 55 mm wing span produced 95% more vertical force at a 26% higher flapping frequency, while the 70 mm wing span produced 165% more vertical force at a 10% lower frequency than the Air Force Institute of Technology baseline wing. Negligible forces and moments were measured at vacuum, where the wing exhibited predominantly inertial motion, revealing flight forces measured in atmosphere are almost wholly limited to interaction with the surrounding air. Lastly, there was a rough correlation between Reynolds number and vertical force, indicating Reynolds number is a useful modelling parameter to predict lift and corresponding aerodynamic coefficients for a specific wing design

The impact of the COVID-19 pandemic on an international rehabilitation study in MS: the CogEx experience

Pandemic restrictions have led to changes in therapy plans and disrupted rehabilitation services for people with multiple sclerosis. CogEx is an international, multicentre MS dual-intervention (cognitive rehabilitation, aerobic exercise) randomized, controlled rehabilitation trial confined to people with progressive disease. The primary outcome is cognition (processing speed).There are 11 treatment sites in six countries with participants required to make 27 site visits over 12 weeks. Collectively, the large, in-person demands of the trial, and the varying international policies for the containment of COVID-19, might disproportionately impact the administration of CogEx. During the first lockdown, all centres closed on average for 82.9 (SD = 24.3) days. One site was required to lockdown on two further occasions. One site remained closed for 16 months. Ten staff (19.2%) were required to quarantine and eight staff (15.4%) tested positive for COVID. 10 of 264 (3.8%) participants acquired COVID-19. All survived. The mean duration of enrollment delay has been [236.7 (SD = 214.5) days]. Restarting participants whose interventions were interrupted by the pandemic meant recalculating the intervention prescriptions for these individuals. While the impact of the pandemic on CogEx has been considerable, all study sites are again open. Participants and staff have shown considerable flexibility and resilience in keeping a complex, international endeavour running. The future in general remains uncertain in the midst of a pandemic, but there is cautious optimism the study will be completed with sufficient sample size to robustly evaluate our hypothesis and provide meaningful results to the MS community on the impact of these interventions on people with progressive MS. Trial registration: The trial was registered on September 20th 2018 at www.clinicaltrials.gov having identifier NCT03679468. Registration was performed before recruitment was initiated

The relationship between processing speed and verbal and non-verbal new learning and memory in progressive multiple sclerosis

Objective: Processing speed (PS) deficits are the most common cognitive deficits in multiple sclerosis (MS), followed by learning and memory deficits, and are often an early cognitive problem. It has been argued that impaired PS is a primary consequence of MS, which in turn decreases learning. The current analysis examined the association between PS and learning in a large cohort of individuals with progressive MS. Methods: Baseline data from a randomized clinical trial on rehabilitation taking place at 11 centers across North America and Europe were analyzed. Participants included 275 individuals with clinically definite progressive MS (primary, secondary) consented into the trial. Results: Symbol Digit Modalities Test (SDMT) significantly correlated with California Verbal Learning Test-II (CVLT-II) (r = 0.21, p = 0.0003) and Brief Visuospatial Memory Test–Revised (BVMT-R) (r = 0.516, p < 0.0001). Receiver operating characteristic (ROC) analysis of the SDMT z score to distinguish between impaired and non-impaired CVLT-II performance demonstrated an area under the curve (AUC) of 0.61 (95% confidence interval (CI): 0.55–0.68) and a threshold of −1.62. ROC analysis between SDMT and BVMT-R resulted in an AUC of 0.77 (95% CI: 0.71–0.83) and threshold of −1.75 for the SDMT z score to predict impaired BVMT-R. Conclusion: Results indicate little ability beyond chance to predict CVLT-II from SDMT (61%), albeit statistically significant. In contrast, there was a 77% chance that the model could distinguish between impaired and non-impaired BVMT-R. Several potential explanations are discussed

Small-Scale and Global Dynamos and the Area and Flux Distributions of Active Regions, Sunspot Groups, and Sunspots: A Multi-Database Study

In this work we take advantage of eleven different sunspot group, sunspot, and active region databases to characterize the area and flux distributions of photospheric magnetic structures. We find that, when taken separately, different databases are better fitted by different distributions (as has been reported previously in the literature). However, we find that all our databases can be reconciled by the simple application of a proportionality constant, and that, in reality, different databases are sampling different parts of a composite distribution. This composite distribution is made up by linear combination of Weibull and log-normal distributions -- where a pure Weibull (log-normal) characterizes the distribution of structures with fluxes below (above) $10^{21}$Mx ($10^{22}$Mx). We propose that this is evidence of two separate mechanisms giving rise to visible structures on the photosphere: one directly connected to the global component of the dynamo (and the generation of bipolar active regions), and the other with the small-scale component of the dynamo (and the fragmentation of magnetic structures due to their interaction with turbulent convection). Additionally, we demonstrate that the Weibull distribution shows the expected linear behavior of a power-law distribution (when extended into smaller fluxes), making our results compatible with the results of Parnell et al. (2009)

Sustained Mps1 activity is required in mitosis to recruit O-Mad2 to the Mad1–C-Mad2 core complex

To satisfy the mitotic checkpoint and drive chromosome congression, the Mps1 kinase lets go of kinetochores by phosphorylating itself in trans (see also related papers by Maciejowski et al. and Santaguida et al. in this issue)

The Diagnostic Utility of Induced Sputum Microscopy and Culture in Childhood Pneumonia.

BACKGROUND.: Sputum microscopy and culture are commonly used for diagnosing the cause of pneumonia in adults but are rarely performed in children due to difficulties in obtaining specimens. Induced sputum is occasionally used to investigate lower respiratory infections in children but has not been widely used in pneumonia etiology studies. METHODS.: We evaluated the diagnostic utility of induced sputum microscopy and culture in patients enrolled in the Pneumonia Etiology Research for Child Health (PERCH) study, a large study of community-acquired pneumonia in children aged 1-59 months. Comparisons were made between induced sputum samples from hospitalized children with radiographically confirmed pneumonia and children categorized as nonpneumonia (due to the absence of prespecified clinical and laboratory signs and absence of infiltrate on chest radiograph). RESULTS.: One induced sputum sample was available for analysis from 3772 (89.1%) of 4232 suspected pneumonia cases enrolled in PERCH. Of these, sputum from 2608 (69.1%) met the quality criterion of <10 squamous epithelial cells per low-power field, and 1162 (44.6%) had radiographic pneumonia. Induced sputum microscopy and culture results were not associated with radiographic pneumonia, regardless of prior antibiotic use, stratification by specific bacteria, or interpretative criteria used. CONCLUSIONS.: The findings of this study do not support the culture of induced sputum specimens as a diagnostic tool for pneumonia in young children as part of routine clinical practice

Safety of Induced Sputum Collection in Children Hospitalized With Severe or Very Severe Pneumonia.

BACKGROUND.: Induced sputum (IS) may provide diagnostic information about the etiology of pneumonia. The safety of this procedure across a heterogeneous population with severe pneumonia in low- and middle-income countries has not been described. METHODS.: IS specimens were obtained as part a 7-country study of the etiology of severe and very severe pneumonia in hospitalized children <5 years of age. Rigorous clinical monitoring was done before, during, and after the procedure to record oxygen requirement, oxygen saturation, respiratory rate, consciousness level, and other evidence of clinical deterioration. Criteria for IS contraindications were predefined and serious adverse events (SAEs) were reported to ethics committees and a central safety monitor. RESULTS.: A total of 4653 IS procedures were done among 3802 children. Thirteen SAEs were reported in relation to collection of IS, or 0.34% of children with at least 1 IS specimen collected (95% confidence interval, 0.15%-0.53%). A drop in oxygen saturation that required supplemental oxygen was the most common SAE. One child died after feeding was reinitiated 2 hours after undergoing sputum induction; this death was categorized as "possibly related" to the procedure. CONCLUSIONS.: The overall frequency of SAEs was very low, and the nature of most SAEs was manageable, demonstrating a low-risk safety profile for IS collection even among severely ill children in low-income-country settings. Healthcare providers should monitor oxygen saturation and requirements during and after IS collection, and assess patients prior to reinitiating feeding after the IS procedure, to ensure patient safety

Standardization of Clinical Assessment and Sample Collection Across All PERCH Study Sites.

BACKGROUND.: Variable adherence to standardized case definitions, clinical procedures, specimen collection techniques, and laboratory methods has complicated the interpretation of previous multicenter pneumonia etiology studies. To circumvent these problems, a program of clinical standardization was embedded in the Pneumonia Etiology Research for Child Health (PERCH) study. METHODS.: Between March 2011 and August 2013, standardized training on the PERCH case definition, clinical procedures, and collection of laboratory specimens was delivered to 331 clinical staff at 9 study sites in 7 countries (The Gambia, Kenya, Mali, South Africa, Zambia, Thailand, and Bangladesh), through 32 on-site courses and a training website. Staff competency was assessed throughout 24 months of enrollment with multiple-choice question (MCQ) examinations, a video quiz, and checklist evaluations of practical skills. RESULTS.: MCQ evaluation was confined to 158 clinical staff members who enrolled PERCH cases and controls, with scores obtained for >86% of eligible staff at each time-point. Median scores after baseline training were ≥80%, and improved by 10 percentage points with refresher training, with no significant intersite differences. Percentage agreement with the clinical trainer on the presence or absence of clinical signs on video clips was high (≥89%), with interobserver concordance being substantial to high (AC1 statistic, 0.62-0.82) for 5 of 6 signs assessed. Staff attained median scores of >90% in checklist evaluations of practical skills. CONCLUSIONS.: Satisfactory clinical standardization was achieved within and across all PERCH sites, providing reassurance that any etiological or clinical differences observed across the study sites are true differences, and not attributable to differences in application of the clinical case definition, interpretation of clinical signs, or in techniques used for clinical measurements or specimen collection