tinySLAM-based exploration with a swarm of nano-UAVs

This paper concerns SLAM and exploration for a swarm of nano-UAVs. The laser range finder-based tinySLAM algorithm is used to build maps of the environment. The maps are synchronized using an iterative closest point algorithm. The UAVs then explore the map by steering to points selected by a modified dynamic coverage algorithm, for which we prove a stability result. Both algorithms inform each other, allowing the UAVs to map out new areas of the environment and move into them for exploration. Experimental findings using the nano-UAV Crazyflie 2.1 platform are presented. A key challenge is to implement all algorithms on the hardware limited experimental platform.Comment: Published at the Sixth International Symposium on Swarm Behavior and Bio-Inspired Robotics 2023 (SWARM 6th 2023). Pages 899-90

Sedimentologische Auswirkungen der Grundfischerei in der Kieler Bucht (Westliche Ostsee)

Sedimentological effects of trawl fishery are little investigated compared to the biological effects. The objectives for the present investigation concern the mechanical disturbance of the sediments and the reworking induced by the ploughing effect of the trawl-net otter boards. For investigation of the distribution of trawl-net tracks on the sediment surface and their morphological analysis highresolving side-scan Sonar and video instruments (ROV) were used, occasionally supported by scuba divers. Manifold mechanical effects on the sediments observed up to 23 cm sediment depth were studied on X-ray graphs from video-controlled box core sampling. The reworking of sediments is due to the suspension cloud during trawling as well as to erosion which acts preferredly at small-scale topography formed by the ploughing effect of the otter boards. Oblique action of the otter boards and their frequently jumping rnotion reduce the surface disturbed by trawling. Sedimentologische Auswirkungen der Grundfischerei sind bisher im Vergleich zu biologischen Effekten wenig untersucht. Die Fragestellung der vorliegenden Arbeit setzt hauptsächlich an den mechanischen Störungen und den Konsequenzen für die Sedimenturnlagerung durch den Einfluß der Grundfischerei, vor allem durch die Pflugwirkung der Scherbretter, im Gebiet der Kieler Bucht an. Die Verbreitung der Grundfischereispuren am Meeresboden wurde mit Hilfe eines hochauflösenden Seitensichtsonars untersucht, für die morphologische Analyse wurden zusätzlich Video- und Tauchbeobachtungen eingesetzt. Die mechanischen Störeffekte wurden an Röntgen-Radiographien untersucht. Die an Radiographien von video-gesteuerten Kastengreiferproben beobachtete Tiefenwirkung der mechanischen Störungen des Sedimentgefüges - Faltungs- und Wickelgefüge, Zerscherungen sowie Laminierung durch Pflugsohleneffekte werden beschrieben - beträgt bis zu 23 cm. Umlagerung erfolgt über die beim Grundfischen erzeugte Suspensionswolke sowie über Erosion, die an den durch die Scherbretter entstandenen Unebenheiten bevorzugt ansetzt. Die Verbreitung der Suspensionswolke erfolgt deshalb mehr lokal, während das erodierte Material durch episodische Bodenströmungen weiter verfrachtet wird. Eine beträchtliche Reduktion der Flächenwirkung der Scherbretter auf Schlickböden erfolgt dadurch, daß diese zum weitaus überwiegenden Teil nur schräg "über Eck" den Grund berühren oder, durch elastische Reaktion des Geschirrs auf den Sedimentwiderstand bedingt, sich hüpfend fortbewegen

Gelation of cereal β-glucan at low concentrations

Viscosity of cereal beta-glucan during digestion is considered to be a vital factor for its health effects. Thus, studies on solution properties and gelation are essential for understanding the mechanisms of the beta-glucan functionality. The aim of this study was to investigate the effect of the dissolution temperature on gelation of cereal beta-glucan at low concentrations that are relevant for food products. The rheological properties of oat and barley beta-glucans (OBG and BBG) using three dissolution temperatures (37 degrees C, 57 degrees C and 85 degrees C) at low concentration (1.5% and 1%, respectively) were studied for 7 days. Additionally, the beta-glucans were oxidised with 70 mM H2O2 and 1 mM FeSO4 x 7H(2)O as a catalyst, to evaluate the consequence of oxidative degradation on the gelation properties. The study showed that dissolution at 85 degrees C did not result in gelation. The optimal dissolution temperature for gelation of OBG was 37 degrees C and for gelation of BBG 57 degrees C. At these temperatures, also the oxidised OBG and BBG gelled, although the gel strength was somewhat lower than in the non-oxidised ones. Gelation was suggested to require partial dissolution of beta-glucan, which depended on the molar mass and aggregation state of the beta-glucan molecule. Therefore, the state of beta-glucan in solution and its thermal treatment history may affect its technological and physiological functionality. (C) 2017 Elsevier Ltd. All rights reserved.Peer reviewe

Single breath N2-test and exhaled nitric oxide in men

SummaryThe N2 slope is an index of inhomogeneous distribution of ventilation and has been suggested to be suited for early testing of chronic obstructive pulmonary disease (COPD) in smokers. The aim of the present study was to examine the association between the fraction of exhaled nitric oxide (FENO) and the N2 slope in a random population of smoking and non-smoking men. Altogether 57 subjects were included in the study, 24 never-smokers, seven ex-smokers and 26 current smokers. Subjects were examined twice, in 1995 when they regarded themselves as healthy, and in a follow-up in 2001. Spirometry, N2 slope and high-resolution computed tomography (HRCT) were performed in 1995 while the follow-up examination included also measurement of FENO.The FENO value was significantly lower and the N2 slope higher in current smokers. In smokers but not in never- or ex-smokers FENO was correlated to the difference in N2 slope between 1995 and 2001 (rs=0.49, P=0.01). We analysed the data by multiple linear regression adjusted for smoking, mild respiratory symptoms and inhaled steroids. There were significant associations between FENO and the N2 slope both in 1995 and in 2001. The strongest association was found to exist with the change in N2 slope during these years.Sixteen of the subjects could be classified as having COPD, six with mild and ten with moderate COPD. There was a trend for an increase in N2 slope with increased severity of COPD; among subjects with no COPD the N2 slope in 2001 was 2.3% N2/L, and those with mild and moderate COPD had 2.5% N2/L and 3.9% N2/L, respectively (P=0.0004). No such trend was seen for FENO (17.8, 15.5 and 20.3 parts per billion (ppb), respectively, P=0.8).The results show that FENO is associated with the N2 slope, indicating that FENO reflects inflammatory changes in the peripheral airways of both non-smoking and smoking subjects

Tomosynthesis in pulmonary cystic fibrosis with comparison to radiography and computed tomography: a pictorial review

The purpose of this pictorial review is to illustrate chest imaging findings of cystic fibrosis (CF) using tomosynthesis (digital tomography), in comparison to radiography and computed tomography (CT). CF is a chronic systemic disease where imaging has long been used for monitoring chest status. CT exposes the patient to a substantially higher radiation dose than radiography, rendering it unsuitable for the often needed repeated examinations of these patients. Tomosynthesis has recently appeared as an interesting low dose alternative to CT, with an effective dose of approximately 0.08 mSv for children and 0.12 mSv for adults. Tomosynthesis is performed on the same X-ray system as radiography, adding only about 1 min to the normal examination time. Typical pulmonary changes in CF such as mucus plugging, bronchial wall thickening, and bronchiectases are shown in significantly better detail with tomosynthesis than with traditional radiography. In addition, the cost for a tomosynthesis examination is low compared to CT. To reduce the radiation burden of patients with CF it is important to consider low dose alternatives to CT, especially in the paediatric population. Tomosynthesis has a lower radiation dose than CT and gives a superior visualisation of pulmonary CF changes compared to radiography. It is important to further determine the role of tomosynthesis for monitoring disease progression in CF

Systematic review with meta-analysis of the epidemiological evidence relating smoking to COPD, chronic bronchitis and emphysema

<p>Abstract</p> <p>Background</p> <p>Smoking is a known cause of the outcomes COPD, chronic bronchitis (CB) and emphysema, but no previous systematic review exists. We summarize evidence for various smoking indices.</p> <p>Methods</p> <p>Based on MEDLINE searches and other sources we obtained papers published to 2006 describing epidemiological studies relating incidence or prevalence of these outcomes to smoking. Studies in children or adolescents, or in populations at high respiratory disease risk or with co-existing diseases were excluded. Study-specific data were extracted on design, exposures and outcomes considered, and confounder adjustment. For each outcome RRs/ORs and 95% CIs were extracted for ever, current and ex smoking and various dose response indices, and meta-analyses and meta-regressions conducted to determine how relationships were modified by various study and RR characteristics.</p> <p>Results</p> <p>Of 218 studies identified, 133 provide data for COPD, 101 for CB and 28 for emphysema. RR estimates are markedly heterogeneous. Based on random-effects meta-analyses of most-adjusted RR/ORs, estimates are elevated for ever smoking (COPD 2.89, CI 2.63-3.17, n = 129 RRs; CB 2.69, 2.50-2.90, n = 114; emphysema 4.51, 3.38-6.02, n = 28), current smoking (COPD 3.51, 3.08-3.99; CB 3.41, 3.13-3.72; emphysema 4.87, 2.83-8.41) and ex smoking (COPD 2.35, 2.11-2.63; CB 1.63, 1.50-1.78; emphysema 3.52, 2.51-4.94). For COPD, RRs are higher for males, for studies conducted in North America, for cigarette smoking rather than any product smoking, and where the unexposed base is never smoking any product, and are markedly lower when asthma is included in the COPD definition. Variations by sex, continent, smoking product and unexposed group are in the same direction for CB, but less clearly demonstrated. For all outcomes RRs are higher when based on mortality, and for COPD are markedly lower when based on lung function. For all outcomes, risk increases with amount smoked and pack-years. Limited data show risk decreases with increasing starting age for COPD and CB and with increasing quitting duration for COPD. No clear relationship is seen with duration of smoking.</p> <p>Conclusions</p> <p>The results confirm and quantify the causal relationships with smoking.</p

Systematic review of the evidence relating FEV1 decline to giving up smoking

<p>Abstract</p> <p>Background</p> <p>The rate of forced expiratory volume in 1 second (FEV₁) decline ("beta") is a marker of chronic obstructive pulmonary disease risk. The reduction in beta after quitting smoking is an upper limit for the reduction achievable from switching to novel nicotine delivery products. We review available evidence to estimate this reduction and quantify the relationship of smoking to beta.</p> <p>Methods</p> <p>Studies were identified, in healthy individuals or patients with respiratory disease, that provided data on beta over at least 2 years of follow-up, separately for those who gave up smoking and other smoking groups. Publications to June 2010 were considered. Independent beta estimates were derived for four main smoking groups: never smokers, ex-smokers (before baseline), quitters (during follow-up) and continuing smokers. Unweighted and inverse variance-weighted regression analyses compared betas in the smoking groups, and in continuing smokers by amount smoked, and estimated whether beta or beta differences between smoking groups varied by age, sex and other factors.</p> <p>Results</p> <p>Forty-seven studies had relevant data, 28 for both sexes and 19 for males. Sixteen studies started before 1970. Mean follow-up was 11 years. On the basis of weighted analysis of 303 betas for the four smoking groups, never smokers had a beta 10.8 mL/yr (95% confidence interval (CI), 8.9 to 12.8) less than continuing smokers. Betas for ex-smokers were 12.4 mL/yr (95% CI, 10.1 to 14.7) less than for continuing smokers, and for quitters, 8.5 mL/yr (95% CI, 5.6 to 11.4) less. These betas were similar to that for never smokers. In continuing smokers, beta increased 0.33 mL/yr per cigarette/day. Beta differences between continuing smokers and those who gave up were greater in patients with respiratory disease or with reduced baseline lung function, but were not clearly related to age or sex.</p> <p>Conclusion</p> <p>The available data have numerous limitations, but clearly show that continuing smokers have a beta that is dose-related and over 10 mL/yr greater than in never smokers, ex-smokers or quitters. The greater decline in those with respiratory disease or reduced lung function is consistent with some smokers having a more rapid rate of FEV₁decline. These results help in designing studies comparing continuing smokers of conventional cigarettes and switchers to novel products.</p