174 research outputs found

    INFLUENCE OF A HETEROGENEOUS HIGH-POLYMER DNA UPON ERYTHROPOIESIS

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    Overfishing of top predators eroded the resilience of the Black Sea system regardless of the climate and anthropogenic conditions

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    It is well known that human activities, such as harvesting, have had major direct effects on marine ecosystems. However, it is far less acknowledged that human activities in the surroundings might have important effects on marine systems. There is growing evidence suggesting that major reorganization (i.e., a regime shift) is a common feature in the temporal evolution of a marine system. Here we show, and quantify, the interaction of human activities (nutrient upload) with a favourable climate (run-off) and its contribution to the eutrophication of the Black Sea in the 1980s. Based on virtual analysis of the bottom-up (eutrophication) vs. top-down (trophic cascades) effects, we found that an earlier onset of eutrophication could have counteracted the restructuring of the trophic regulation at the base of the food web that resulted from the depletion of top predators in the 1970s. These enhanced bottom-up effects would, however, not propagate upwards in the food web beyond the zooplankton level. Our simulations identified the removal of apex predators as a key element in terms of loss of resilience that inevitably leads to a reorganization. Once the food web has been truncated, the type and magnitude of interventions on the group replacing the apex predator as the new upper trophic level have no effect in preventing the trophic cascade. By characterizing the tipping point at which increased bottom-up forcing exactly counteracts the top-down cascading effects, our results emphasize the importance of a comprehensive analysis that take into account all structuring forces at play (including those beyond the marine system) at a given time.EUR-OCEANS Integration Project 2007; Marie Curie Intra-European fellowship [FP6-2005-Mobility-5]; Marie Curie European Reintegration Grant [FP7-People- 2009-RG]; EU WETLANET, KNOWSEAS, and MEECE, UK NERC QUEST; US National Science Foundation (DMS-0935617

    Astigmatism management during cataract surgery

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    Цел: да обсъдим и споделим нашия опит при интраоперативната корекция на роговичния астигматизъм по време на катарактна хирургия. Методи: В проучването са включени 48 пациенти с различна степен на роговичен астигматизъм, разделени в две групи. Подборът на метода на корекция на астигматизма беше направен на база на степента на астигматизма след изследване на роговицата с корнеален топограф и томограф. Пациентите с роговичен астигматизъм до 2,5 Д -38 очи третирахме с АК (аркуатни кератотомии), извършени с B&L VICTUS Femtosecond Laser P1atform , при останалите 11 очи имплантирахме торична вътреочна леща. Проследихме пациентите за период от 18 месеца постоперативно. Резултати: И в двете групи получихме желаната корекция на астигматизма постоперативно, В първата група редукцията на астигматизма беше средно 1, 71 dpt ± 0,63 (SD) до 0,28 ± 0,39 (РObjective: To share our experience in correcting corneal astigmatism in patients undergoing cataract surgery. Methods: Our study includes 48 eyes, 37 eyes with a corneal astigmatism of up to 2.50 dpt and 11 eyes with a higher (>2.50dpt) astigmatism. The first group was treated with arcuate keratotomies (AK) performed by B&L VICTUS Femtosecond Laser Platform. The AKs were placed on the steepest corneal meridian in a resulting depth of 85% based on the real-time OCT pachymetry. Patients from group 2 were treated with intraocular toric IOLs. Postsurgical follow-up period was 18 months and includes uncorrected visual acuity, manifest refraction, count and density of endothelial corneal cells prior to and after surgery, pachymetry, corneal topography (Placidobased and Scheimpflug image -derived topography). Results: - The mean astigmatismus reduction in the first group was from 1.71 D ± 0.63 (SD) to 0.28 ± 0.39 D (

    (New) Bulgarian Enlighteners and Ambassadors? The Reinvention of National Identity in Times of Crisis

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    Drawing on empirical data from 37 Bulgarian students and young professionals in the UK, this article explores the intersection of the discourses produced by the European crises and migrants' national identity. In Bulgaria, the crisis narrative is embedded in the arguably never‐ending democratic transition, manifested in socio‐economic instability and political volatility. Simultaneously, “Brexit Britain” is enveloped in strong Eurosceptic sentiments, propelled by a combination of austerity measures and intensified Eastern European migratory flows. Both contexts subject Bulgarian migrants to stigmatizing representations. Looking at migrants' everyday practices, the data reveals that young Bulgarians draw on the related ideas of the “new” Enlightener and Ambassador to counterbalance negative discourses. Thus, the article explores the meanings and significance attributed to the Enlighteners and the Ambassadors, arguing that the participants engage in “social creativity” and “individual mobility” strategies that lead to reinvention of national identity

    Removal of power-line interference from the ECG: a review of the subtraction procedure

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    BACKGROUND: Modern biomedical amplifiers have a very high common mode rejection ratio. Nevertheless, recordings are often contaminated by residual power-line interference. Traditional analogue and digital filters are known to suppress ECG components near to the power-line frequency. Different types of digital notch filters are widely used despite their inherent contradiction: tolerable signal distortion needs a narrow frequency band, which leads to ineffective filtering in cases of larger frequency deviation of the interference. Adaptive filtering introduces unacceptable transient response time, especially after steep and large QRS complexes. Other available techniques such as Fourier transform do not work in real time. The subtraction procedure is found to cope better with this problem. METHOD: The subtraction procedure was developed some two decades ago, and almost totally eliminates power-line interference from the ECG signal. This procedure does not affect the signal frequency components around the interfering frequency. Digital filtering is applied on linear segments of the signal to remove the interference components. These interference components are stored and further subtracted from the signal wherever non-linear segments are encountered. RESULTS: Modifications of the subtraction procedure have been used in thousands of ECG instruments and computer-aided systems. Other work has extended this procedure to almost all possible cases of sampling rate and interference frequency variation. Improved structure of the on-line procedure has worked successfully regardless of the multiplicity between the sampling rate and the interference frequency. Such flexibility is due to the use of specific filter modules. CONCLUSION: The subtraction procedure has largely proved advantageous over other methods for power-line interference cancellation in ECG signals

    Dataset of manually measured QT intervals in the electrocardiogram

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    BACKGROUND: The QT interval and the QT dispersion are currently a subject of considerable interest. Cardiac repolarization delay is known to favor the development of arrhythmias. The QT dispersion, defined as the difference between the longest and the shortest QT intervals or as the standard deviation of the QT duration in the 12-lead ECG is assumed to be reliable predictor of cardiovascular mortality. The seventh annual PhysioNet/Computers in Cardiology Challenge, 2006 addresses a question of high clinical interest: Can the QT interval be measured by fully automated methods with accuracy acceptable for clinical evaluations? METHOD: The PTB Diagnostic ECG Database was given to 4 cardiologists and 1 biomedical engineer for manual marking of QRS onsets and T-wave ends in 458 recordings. Each recording consisted of one selected beat in lead II, chosen visually to have minimum baseline shift, noise, and artifact. In cases where no T wave could be observed or its amplitude was very small, the referees were instructed to mark a 'group-T-wave end' taking into consideration leads with better manifested T wave. A modified Delphi approach was used, which included up to three rounds of measurements to obtain results closer to the median. RESULTS: A total amount of 2*5*548 Q-onsets and T-wave ends were manually marked during round 1. To obtain closer to the median results, 8.58 % of Q-onsets and 3.21 % of the T-wave ends had to be reviewed during round 2, and 1.50 % Q-onsets and 1.17 % T-wave ends in round 3. The mean and standard deviation of the differences between the values of the referees and the median after round 3 were 2.43 ± 0.96 ms for the Q-onset, and 7.43 ± 3.44 ms for the T-wave end. CONCLUSION: A fully accessible, on the Internet, dataset of manually measured Q-onsets and T-wave ends was created and presented in additional file: 1 (Table 4) with this article. Thus, an available standard can be used for the development of automated methods for the detection of Q-onsets, T-wave ends and for QT interval measurements

    Ventricular beat detection in single channel electrocardiograms

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    BACKGROUND: Detection of QRS complexes and other types of ventricular beats is a basic component of ECG analysis. Many algorithms have been proposed and used because of the waves' shape diversity. Detection in a single channel ECG is important for several applications, such as in defibrillators and specialized monitors. METHODS: The developed heuristic algorithm for ventricular beat detection includes two main criteria. The first of them is based on steep edges and sharp peaks evaluation and classifies normal QRS complexes in real time. The second criterion identifies ectopic beats by occurrence of biphasic wave. It is modified to work with a delay of one RR interval in case of long RR intervals. Other algorithm branches classify already detected QRS complexes as ectopic beats if a set of wave parameters is encountered or the ratio of latest two RR intervals RR(i-1)/RR(i )is less than 1:2.5. RESULTS: The algorithm was tested with the AHA and MIT-BIH databases. A sensitivity of 99.04% and a specificity of 99.62% were obtained in detection of 542014 beats. CONCLUSION: The algorithm copes successfully with different complicated cases of single channel ventricular beat detection. It is aimed to simulate to some extent the experience of the cardiologist, rather than to rely on mathematical approaches adopted from the theory of signal analysis. The algorithm is open to improvement, especially in the part concerning the discrimination between normal QRS complexes and ectopic beats

    37<sup>th</sup> plenary meeting report of the scientific, technical and economic committee for fisheries (PLEN-11-02)

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    The Scientific, Technical and Economic Committee for Fisheries hold its 37th plenary on 11-15 July 2011 in Copenhagen (Denmark). The terms of reference included both issues assessments of STECF Expert Working Group reports and additional requests submitted to the STECF by the Commission. Topics dealt with ranged from fisheries economics to management plan evaluation issues
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