A prototype of an autonomous controller for a quadrotor UAV

The paper proposes a complete real-time control algorithm for autonomous collision-free operations of the quadrotor UAV. As opposed to fixed wing vehicles the quadrotor is a small agile vehicle which might be more suitable for the variety of specific applications including search and rescue, surveillance and remote inspection. The developed control system incorporates both trajectory planning and path following. Using a differential flatness property the trajectory planning is posed as a constrained optimization problem in the output space (as opposed to the control space), which simplifies the problem. The trajectory and speed profile are parameterized to reduce the problem to a finite dimensional problem. To optimize the speed profile independently of the trajectory a virtual argument is used as opposed to time. A path following portion of the proposed algorithm uses a standard linear multi-variable control technique. The paper presents the results of simulations to demonstrate the suitability of the proposed control algorithm

Exercise intensity while hooked is associated with physiological status of longline-captured sharks

Some shark populations face declines owing to targeted capture and by-catch in longline fisheries. Exercise intensity during longline capture and physiological status may be associated, which could inform management strategies aimed at reducing the impacts of longline capture on sharks. The purpose of this study was to characterize relationships between exercise inten- sity and physiological status of longline-captured nurse sharks (Ginglymostoma cirratum) and Caribbean reef sharks (Carcharhinus perezi). Exercise intensity of longline-captured sharks was quantified with digital cameras and accelerometers, which was paired with blood-based physiological metrics from samples obtained immediately post-capture. Exercise intensity was associated with physiological status following longline capture. For nurse sharks, blood pH increased with capture dur- ation and the proportion of time exhibiting low-intensity exercise. Nurse sharks also had higher blood glucose and plasma potassium concentrations at higher sea surface temperatures. Associations between exercise intensity and physiological sta- tus for Caribbean reef sharks were equivocal; capture duration had a positive relation with blood lactate concentrations and a negative relationship with plasma chloride concentrations. Because Caribbean reef sharks did not appear able to influence blood pH through exercise intensity, this species was considered more vulnerable to physiological impairment. While both species appear quite resilient to longline capture, it remains to be determined if exercise intensity during capture is a useful tool for predicting mortality or tertiary sub-lethal consequences. Fisheries management should consider exercise during cap- ture for sharks when developing techniques to avoid by-catch or reduce physiological stress associated with capture

The unusual occurrence of green algal balls of <i>Chaetomorpha linum</i> on a beach in Sydney, Australia.

In spring 2014, thousands of green algal balls were washed up at Dee Why Beach, Sydney, New South Wales, Australia. Reports of algal balls are uncommon in marine systems, and mass strandings on beaches are even more rare, sparking both public and scientific interest. We identified the algal masses as Chaetomorpha linum by using light microscopy and DNA sequencing. We characterize the size and composition of the balls from Dee Why Beach and compare them to previous records of marine algal balls. We describe the environmental conditions that could explain their appearance, given the ecophysiology of C. linum

Current- and Wave-Generated Bedforms on Mixed Sand–Clay Intertidal Flats:A New Bedform Phase Diagram and Implications for Bed Roughness and Preservation Potential

The effect of bedforms on frictional roughness felt by the overlying flow is crucial to the regional modelling of estuaries and coastal seas. Bedforms are also a key marker of palaeoenvironments. Experiments have shown that even modest biotic and abiotic cohesion in sand inhibits bedform formation, modifies bedform size, and slows bedform development, but this has rarely been tested in nature. The present study used a comprehensive dataset recorded over a complete spring–neap cycle on an intertidal flat to investigate bedform dynamics controlled by a wide range of wave and current conditions, including the effects of wave–current angle and bed cohesion. A detailed picture of different bedform types and their relationship to the flow, be they equilibrium, non-equilibrium, or relict, was produced, and captured in a phase diagram that integrates wave-dominated, current-dominated, and combined wave–current bedforms. This bedform phase diagram incorporates a substantially wider range of flow conditions than previous phase diagrams, including bedforms related to near-orthogonal wave–current angles, such as ladderback ripples. Comparison with laboratory-derived bedform phase diagrams indicates that washed-out ripples, lunate interference ripples and upper-stage plane beds replace the subaqueous dune field; such bedform distributions may be a key characteristic of intertidal flats. The field data also provide a means of predicting the dimensions of these bedforms, which can be transferred to other areas and grain sizes. We show that an equation for the prediction of equilibrium bedform size is sufficient to predict the roughness, even though the bedforms are highly variable in character and only in equilibrium with the flow for approximately half the time. Whilst the effect of cohesive clay is limited under more active spring conditions, clay does play a role in reducing the bedform dimensions under more quiescent neap conditions. We also investigated which combinations of waves, currents, and bed clay contents in the intertidal zone have the highest potential for bedform preservation in the geological record. This shows that combined wave–current bedforms have the lowest preservation potential and equilibrium current ripples have the highest preservation potential, even in the presence of moderate and storm waves. Hence, the absence of wave ripples and combined-flow bedforms and their primary stratification in sedimentary successions cannot be taken as evidence that waves were absent at the time of deposition

Current- and wave- generated bedforms on mixed sand-clay intertidal flats : a new bedform phase diagram and implications for bed roughness and preservation potential

Funding: This work was supported by the United Kingdom’s Natural Environment Research Council (NERC) under Grant NE/I027223/1 (COHBED). JM, Julie Hope, and Daniel Parsons were partially funded by a Horizon 2020 European Research Council Consolidator Award (GEOSTICK, Grant 725955). The GEOSTICK project also kindly contributed the article processing fees. Andrew Manning’s contribution toward this research was partly supported by the National Science Foundation grants OCE-1924532 and OCE-1736668, TKI-MUSA project 11204950-000-ZKS-0002, and the HR Wallingford company research project FineScale (Grant Nos. ACK3013_62). DP received funding from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland) and their support is gratefully acknowledged. MASTS is funded by the Scottish Funding Council (Grant reference HR09011) and contributing institutions.The effect of bedforms on frictional roughness felt by the overlying flow is crucial to the regional modelling of estuaries and coastal seas. Bedforms are also a key marker of palaeoenvironments. Experiments have shown that even modest biotic and abiotic cohesion in sand inhibits bedform formation, modifies bedform size, and slows bedform development, but this has rarely been tested in nature. The present study used a comprehensive dataset recorded over a complete spring–neap cycle on an intertidal flat to investigate bedform dynamics controlled by a wide range of wave and current conditions, including the effects of wave–current angle and bed cohesion. A detailed picture of different bedform types and their relationship to the flow, be they equilibrium, non-equilibrium, or relict, was produced, and captured in a phase diagram that integrates wave-dominated, current-dominated, and combined wave–current bedforms. This bedform phase diagram incorporates a substantially wider range of flow conditions than previous phase diagrams, including bedforms related to near-orthogonal wave–current angles, such as ladderback ripples. Comparison with laboratory-derived bedform phase diagrams indicates that washed-out ripples, lunate interference ripples and upper-stage plane beds replace the subaqueous dune field; such bedform distributions may be a key characteristic of intertidal flats. The field data also provide a means of predicting the dimensions of these bedforms, which can be transferred to other areas and grain sizes. We show that an equation for the prediction of equilibrium bedform size is sufficient to predict the roughness, even though the bedforms are highly variable in character and only in equilibrium with the flow for approximately half the time. Whilst the effect of cohesive clay is limited under more active spring conditions, clay does play a role in reducing the bedform dimensions under more quiescent neap conditions. We also investigated which combinations of waves, currents, and bed clay contents in the intertidal zone have the highest potential for bedform preservation in the geological record. This shows that combined wave–current bedforms have the lowest preservation potential and equilibrium current ripples have the highest preservation potential, even in the presence of moderate and storm waves. Hence, the absence of wave ripples and combined-flow bedforms and their primary stratification in sedimentary successions cannot be taken as evidence that waves were absent at the time of deposition.Publisher PDFPeer reviewe

Rates, predictive factors and effectiveness of ustekinumab intensification to 4- or 6-weekly intervals in Crohn's disease

Background: The UNITI trial reports efficacy of ustekinumab (UST) dose intensification in Crohn's disease (CD) from 12- to 8-weekly, but not 4-weekly. We aimed 1) to assess the cumulative incidence of UST dose intensification to 4- or 6-weekly, 2) to identify factors associated with dose intensification, and 3) to assess the effectiveness of this strategy. Methods: We performed a retrospective, observational cohort study in NHS Lothian including all UST treated CD patients (2015–2020). Results: 163 CD patients were treated with UST (median follow-up: 20.3 months [13.4–38.4]), of whom 55 (33.7%) underwent dose intensification to 4-weekly (n = 50, 30.7%) or 6-weekly (n = 5, 3.1%). After 1 year 29.9% were dose intensified. Prior exposure to both anti-TNF and vedolizumab (HR 9.5; 1.3–70.9), and concomitant steroid use at UST start (HR 1.8; 1.0–3.1) were associated with dose intensification. Following dose intensification, 62.6% patients (29/55) remained on UST beyond 1 year. Corticosteroid-free clinical remission was achieved in 27% at week 16 and 29.6% at last follow-up. Conclusion: One third of CD patients treated with UST underwent dose intensification to a 4- or 6-weekly interval within the first year. Patients who failed both anti-TNF and vedolizumab, or required steroids at initiation were more likely to dose intensify.</p

Effects of surgically implanted tags and translocation on the movements of common bream Abramis brama (L.)

Data collected from wildlife telemetry studies relies on tagging and attachment having minimal impactson behaviour. Though a widespread technique, relatively few studies evaluate the impacts of differingtagging methods on both welfare and behaviour. Here we use tracking data, collected for other aims, toinvestigate the impact of inter-peritoneal surgical implantation of acoustic transmitters on the healthand behaviour of common bream, Abramis brama (L.). In five separate capture events, the behaviour interms of distances moved and linear range of newly tagged fish (n = 61) were compared to previouslytagged fish (n = 55) present in the same river at the same time. In the first 5 days post-tagging, newlytagged fish moved significantly further than previously tagged fish. Despite this difference, the linearranges moved by the two groups of fish were equivalent. During 6–10 days post tagging there was nosignificant differences between the two groups. Thus, the tagging procedure had short term, but not longterm behavioural impacts. In addition, a number of tagged fish were recaptured between 51 and 461days post-surgery. Recaptured fish appeared to have clean, well-healed incisions and exhibited ‘normal’behaviour in that they were caught alongside a large number of conspecifics. Three recaptured taggedfish were translocated ∼35 km downstream, to ascertain how translocation would affect their behaviour.The translocated fish had a greater linear range than control fish, with all three fish returning to the siteof capture within 6 to 24 days, suggesting that common bream can exhibit site fidelity

Reasons to Be Skeptical about Sentience and Pain in Fishes and Aquatic Invertebrates

The welfare of fishes and aquatic invertebrates is important, and several jurisdictions have included these taxa under welfare regulation in recent years. Regulation of welfare requires use of scientifically validated welfare criteria. This is why applying Mertonian skepticism toward claims for sentience and pain in fishes and aquatic invertebrates is scientifically sound and prudent, particularly when those claims are used to justify legislation regulating the welfare of these taxa. Enacting welfare legislation for these taxa without strong scientific evidence is a societal and political choice that risks creating scientific and interpretational problems as well as major policy challenges, including the potential to generate significant unintended consequences. In contrast, a more rigorous science-based approach to the welfare of aquatic organisms that is based on verified, validated and measurable endpoints is more likely to result in “win-win” scenarios that minimize the risk of unintended negative impacts for all stakeholders, including fish and aquatic invertebrates. The authors identify as supporters of animal welfare, and emphasize that this issue is not about choosing between welfare and no welfare for fish and aquatic invertebrates, but rather to ensure that important decisions about their welfare are based on scientifically robust evidence. These ten reasons are delivered in the spirit of organized skepticism to orient legislators, decision makers and the scientific community, and alert them to the need to maintain a high scientific evidential bar for any operational welfare indicators used for aquatic animals, particularly those mandated by legislation. Moving forward, maintaining the highest scientific standards is vitally important, in order to protect not only aquatic animal welfare, but also global food security and the welfare of humans

Patterns of emergency admission for IBD patients over the last 10 years in Lothian, Scotland: A retrospective prevalent cohort analysis

OBJECTIVE: It is unclear how the compounding prevalence of inflammatory bowel disease (IBD) has translated into the causes and rates of hospitalisation, particularly in an era of increased biologic prescribing. We aimed to analyse these trends in a population-based IBD cohort over the last 10 years. DESIGN: The Lothian IBD registry is a complete, validated, prevalent database of IBD patients in NHS Lothian, Scotland. ICD-10 coding of hospital discharge letters from all IBD patient admissions to secondary care between 1 January 2010 and 31 December 2019 was interrogated for admission cause, with linkage to local/national data sets on death and prescribed drugs. RESULTS: Fifty-seven per cent (4673/8211) of all IBD patients were admitted to secondary care for >24 h between 1 January 2010 and 31 December 2019. In patients 60 years (19% of admissions). Three per cent (243/8211) of IBD patients accounted for 50% of the total IBD bed-days over the study period. Age-standardised IBD admission rates fell from 39.4 to 25.5 admissions per 100,000 population between 2010 and 2019, an average annual percentage reduction of 3% (95% CI -4.5% to -2.1%, p < 0.0001). Non-IBD admission rates were unchanged overall (145-137 per 100,000 population) and specifically for serious (hospitalisation) and severe (ITU admission or death) infection over the same period. CONCLUSION: Despite compounding prevalence and increased biologic use, IBD admission rates are falling. The cause of admission varies with age, with infection the predominant cause in older patients

Effectiveness and Safety of Adalimumab Biosimilar SB5 in IBD:Outcomes in Originator to SB5 Switch, Double Biosimilar Switch and Bio-Naieve SB5 Observational Cohorts

BACKGROUND AND AIMS: Multiple adalimumab [ADA] biosimilars are now approved for use in inflammatory bowel disease [IBD]; however, effectiveness and safety data remain scarce. We aimed to investigate long-term outcomes of the ADA biosimilar SB5 in IBD patients following a switch from the ADA originator [SB5-switch cohort] or after start of SB5 [SB5-start cohort]. METHODS: We performed an observational cohort study in a tertiary IBD referral centre. All IBD patients treated with Humira underwent an elective switch to SB5. We identified all these patients in a biological prescription database that prospectively registered all ADA start and stop dates including brand names. Data on IBD phenotype, C-reactive protein [CRP], drug persistence, ADA drug and antibody levels, and faecal calprotectin were collected. RESULTS: In total, 481 patients were treated with SB5, 256 in the SB5-switch cohort (median follow-up: 13.7 months [IQR 8.6–15.2]) and 225 in the SB5-start cohort [median follow-up: 8.3 months [4.2–12.8]). Of the SB5-switch cohort, 70.8% remained on SB5 beyond 1 year; 90/256 discontinued SB5, mainly due to adverse events [46/90] or secondary loss of response [37/90]. In the SB5-start cohort, 81/225 discontinued SB5, resulting in SB5-drug persistence of 60.3% beyond 1 year. No differences in clinical remission [p = 0.53], CRP [p = 0.80], faecal calprotectin [p = 0.40] and ADA trough levels [p = 0.55] were found between baseline, week 26 and week 52 following switch. Injection site pain was the most frequently reported adverse event. CONCLUSION: Switching from ADA originator to SB5 appeared effective and safe in this study with over 12 months of follow-up