1,031 research outputs found

    Anchoring of proteins to lactic acid bacteria

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    The anchoring of proteins to the cell surface of lactic acid bacteria (LAB) using genetic techniques is an exciting and emerging research area that holds great promise for a wide variety of biotechnological applications. This paper reviews five different types of anchoring domains that have been explored for their efficiency in attaching hybrid proteins to the cell membrane or cell wall of LAB. The most exploited anchoring regions are those with the LPXTG box that bind the proteins in a covalent way to the cell wall. In recent years, two new modes of cell wall protein anchoring have been studied and these may provide new approaches in surface display. The important progress that is being made with cell surface display of chimaeric proteins in the areas of vaccine development and enzyme- or whole-cell immobilisation is highlighted.

    The bashful and the boastful : prestigious leaders and social change in Mesolithic Societies

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    The creation and maintenance of influential leaders and authorities is one of the key themes of archaeological and historical enquiry. However the social dynamics of authorities and leaders in the Mesolithic remains a largely unexplored area of study. The role and influence of authorities can be remarkably different in different situations yet they exist in all societies and in almost all social contexts from playgrounds to parliaments. Here we explore the literature on the dynamics of authority creation, maintenance and contestation in egalitarian societies, and discuss the implications for our interpretation and understanding of the formation of authorities and leaders and changing social relationships within the Mesolithic

    The influence of postgraduate qualifications on educational identity formation of healthcare professionals

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    Demand for postgraduate qualifications in medical education can be judged by the increase in providers worldwide over the last two decades. However, research into the impact of such courses on identity formation of healthcare professionals is limited. This study investigates the influence of such programmes on graduates’ educational identities, practices and career progression. Informed by constructivist grounded theory (CGT), semi-structured interviews were conducted with 27 graduates (2008–2012) from one postgraduate programme, who were at different stages in their careers worldwide. The audio data were transcribed and analysed using a CGT approach. Participants enrolled in award-bearing medical education courses for various intrinsic and extrinsic reasons. The findings from this study highlight their development as educators, and educational researchers, leaders and learners, as their self-efficacy in educational practices and engagement in scholarly activities increased. Graduates attributed career progression to the qualification, with many being promoted into senior positions. They also described substantial performance attainments in the workplace. The findings contribute to understanding the complexity and nuances of educational identity formation of healthcare professionals. A qualification in medical education encouraged transformational changes and epistemological development as an educator. Awareness of these findings will inform both those considering enrolment and those supporting them of potential benefits of these programmes

    Launch & Early Operations Phase (LEOP) Iridium EyeStar-S4 24-7 Link With Mosaic-X5 GPS and Launch Results

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    Satellite Mission Success is best achieved during the Launch Early Operations Phase (LEOP) when a satellite first becomes alive as radio data (TT&C) appears on the ground station within seconds. Using the Iridium global network, no matter where a tumbling satellite is in orbit, TT&C data is available anywhere-anytime. Diagnostic data, GPS, spin rates, live ADCS, temperatures, voltages, electrical power systems, primary processor, deployments, and payload monitors like plasma density or integral particle fluxes can all be tracked during the turn-on process with the option of disabling or adjusting command parameters to the unexpected. Several EyeStar-S4 flight NSL/Iridium transceivers can be linked to each bus subsystem or payload for quick-look data using the S4 microcontroller for a direct link to the ground. Although each S4 data rate is low (up to 100 bytes/s in some cases) the selected compressed data from each parallel S4 link can provide a wealth of information and science data with the TM frame formatter. After the LEOP phase of a few days, the S4 link can be optimized for sending back prompt, quick look, diagnostic, and scientific data for mission duration. Flight results are shown of the S4 Iridium link from the NSL S4-CROSSOVER Sat (Astra launch, March 8, 2022) and the NSL TROOP-3 Sat (SpaceX launch, May 25, 2022). Each was in ~525 km polar orbit and tumbling at 40 and 8 RPM, respectively. Both the satellites sent first light packets of data soon after first transmitter turn-on to the NSL console via Iridium. Both rad tolerant satellites were operating for close two years before being decommissioned in early 2024. NSL delivered the TROOP-F2 satellite (6U) for a SpaceX launch in June 2024. The satellite includes 1) three NSL-Iridium S4 transceivers with different antennas and pointing, 2) several Space Weather NSL-SWAP-E Lite sensors (Low Energy particle detector, Medium Energy Particle spectrometers, a total integral dose particle detector and a Plasma Probe), 3) several NSL Bus systems (new Mosaic-X5 GPS, new ADCS, EPS, rad hard solar cells, 900 MHz link for Sat-Sat or Sat-Ground transceiver, processors) and 4) a primary rendezvous experiment payload. In addition, 5) NSL has added two more GPS antennas to test the differential GPS capability (high-position accuracy and attitude determination required for science, rendezvous, and lower cross section for orbital debris mitigation). The 6U SWAP-E (Space Weather Array Prompt Experiment) four-satellite constellation and the 6U RAPSat three-satellite mission are scheduled for late 2024 launch (they have 22 Flight S4 transceivers). To date NSL has 100% success of all flight EyeStar- early S3\u27s and current S4\u27s in orbit and the time ordered database on the NSL secured console is ideal for analyses and constellations. Automation is everywhere in the S4 Iridium link from robotic assembly to smart algorithms. The web console is accessible from desktop or mobile to check incoming packets, send uplink commands, or receive SMS notifications. A Web API allows programmatic access

    Prospects for Creation of Cardioprotective and Antiarrhythmic Drugs Based on Opioid Receptor Agonists

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    It has now been demonstrated that the μ, δ(1), δ(2), and κ(1) opioid receptor (OR) agonists represent the most promising group of opioids for the creation of drugs enhancing cardiac tolerance to the detrimental effects of ischemia/reperfusion (I/R). Opioids are able to prevent necrosis and apoptosis of cardiomyocytes during I/R and improve cardiac contractility in the reperfusion period. The OR agonists exert an infarct‐reducing effect with prophylactic administration and prevent reperfusion‐induced cardiomyocyte death when ischemic injury of heart has already occurred; that is, opioids can mimic preconditioning and postconditioning phenomena. Furthermore, opioids are also effective in preventing ischemia‐induced arrhythmias

    The antiarrhythmic actions of bisaramil and penticainide result from mixed cardiac ion channel blockade

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    Decades of focus on selective ion channel blockade has been dismissed as an effective approach to antiarrhythmic drug development. In that context many older antiarrhythmic drugs lacking ion channel selectivity may serve as tools to explore mixed ion channel blockade producing antiarrhythmic activity. This study investigated the non-clinical electrophysiological and antiarrhythmic actions of bisaramil and penticainide using in vitro and in vivo methods. In isolated cardiac myocytes both drugs directly block sodium currents with IC50 values of 13μM (bisaramil) and 60μM (penticainide). Both drugs reduced heart rate but prolonged the P-R, QRS and Q-T intervals of the ECG (due to sodium and potassium channel blockade) in intact rats. They reduced cardiac conduction velocity in isolated rat hearts, increased the threshold currents for capture and fibrillation (indices of sodium channel blockade) and reduced the maximum following frequency as well as prolonged the effective refractory period (indices of potassium channel blockade) of electrically stimulated rat hearts. Both drugs reduced ventricular arrhythmias and eliminated mortality due to VF in ischemic rat hearts. The index of cardiac electrophysiological balance (iCEB) did not change significantly over the dose range evaluated; however, different drug effects resulted when changes in BP and HR were considered. While bisaramil is a more potent sodium channel blocker compared to penticainide, both produce a spectrum of activity against ventricular arrhythmias due to mixed cardiac ion channel blockade. Antiarrhythmic drugs exhibiting mixed ion channel blockade may serve as tools for development of safer mixed ion channel blocking antiarrhythmic drugs.M.K. Pugsley, E.S. Hayes, D.A. Saint, M.J.A. Walke

    Atmospheric radiocarbon measurements to quantify CO<sub>2</sub> emissions in the UK from 2014 to 2015

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    We present Δ14CO2 observations and related greenhouse gas measurements at a background site in Ireland (Mace Head, MHD) and a tall tower site in the east of the UK (Tacolneston, TAC) that is more strongly influenced by fossil fuel sources. These observations have been used to calculate the contribution of fossil fuel sources to the atmospheric CO2 mole fractions; this can be done, as emissions from fossil fuels do not contain 14CO2 and cause a depletion in the observed Δ14CO2 value. The observations are compared to simulated values. Two corrections need to be applied to radiocarbon-derived fossil fuel CO2 (ffCO2): one for pure 14CO2 emissions from nuclear industry sites and one for a disequilibrium in the isotopic signature of older biospheric emissions (heterotrophic respiration) and CO2 in the atmosphere. Measurements at both sites were found to only be marginally affected by 14CO2 emissions from nuclear sites. Over the study period of 2014–2015, the biospheric correction and the correction for nuclear 14CO2 emissions were similar at 0.34 and 0.25 ppm ffCO2 equivalent, respectively. The observed ffCO2 at the TAC tall tower site was not significantly different from simulated values based on the EDGAR 2010 bottom-up inventory. We explored the use of high-frequency CO observations as a tracer of ffCO2 by deriving a constant ratio of CO enhancements to ffCO2 ratio for the mix of UK fossil fuel sources. This ratio was found to be 5.7 ppb ppm−1, close to the value predicted using inventories and the atmospheric model of 5.1 ppb ppm−1. The TAC site, in the east of the UK, was strategically chosen to be some distance from pollution sources so as to allow for the observation of well-integrated air masses. However, this distance from pollution sources and the large measurement uncertainty in 14CO2 lead to a large overall uncertainty in the ffCO2, being around 1.8 ppm compared to typical enhancements of 2 ppm
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