45 research outputs found

    Positronium Hyperfine Splitting in Non-commutative Space at the Order α6\alpha^6

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    We obtain positronium Hyperfine Splitting owing to the non-commutativity of space and show that, in the leading order, it is proportional to Ξα6\theta \alpha^6 where, Ξ\theta is the parameter of non-commutativity. It is also shown that spatial non-commutativity splits the spacing between n=2n=2 triplet excited levels E(23S1)→E(23P2)E(2^3S_1)\to E(2^3P_2) which provides an experimental test on the non-commutativity of space.Comment: 7 pages, 2 figures, to appear in Phys. Rev.

    Search for C-violating, P-conserving interactions and observation of 23S1 to 21P1 transitions in positronium

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    Possible C-forbidden transitions between 23S1 and 21P1 states of positronium are investigated. Limits are placed on the CP-violating state-mixing matrix element:|1P1|HHCP| 23P1>| 1P1 states and measurement of the 23S1 to 21P1 transition frequency, v0=11181 +/- 13 MHz, verifying QED calculations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30784/1/0000437.pd

    The Effect of Data Augmentation on Classification of Atrial Fibrillation in Short Single-Lead ECG Signals Using Deep Neural Networks

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    Cardiovascular diseases are the most common cause of mortality worldwide. Detection of atrial fibrillation (AF) in the asymptomatic stage can help prevent strokes. It also improves clinical decision making through the delivery of suitable treatment such as, anticoagulant therapy, in a timely manner. The clinical significance of such early detection of AF in electrocardiogram (ECG) signals has inspired numerous studies in recent years, of which many aim to solve this task by leveraging machine learning algorithms. ECG datasets containing AF samples, however, usually suffer from severe class imbalance, which if unaccounted for, affects the performance of classification algorithms. Data augmentation is a popular solution to tackle this problem. In this study, we investigate the impact of various data augmentation algorithms, e.g., oversampling, Gaussian Mixture Models (GMMs) and Generative Adversarial Networks (GANs), on solving the class imbalance problem. These algorithms are quantitatively and qualitatively evaluated, compared and discussed in detail. The results show that deep learning-based AF signal classification methods benefit more from data augmentation using GANs and GMMs, than oversampling. Furthermore, the GAN results in circa 3% better AF classification accuracy in average while performing comparably to the GMM in terms of f1-score

    Dual-band magneto-electric dipole antenna with high-gain for base-station applications

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    The paper presents the results of a novel high-gain dual-band magneto-electric dipole (MED) antenna. The antenna comprises two pairs of horizontal metal plates of different heights that are excited by a Γ-shaped feedline structure. The antenna is entirely made of metal plates. Compared to traditional MED antennas the proposed design exhibits dual-band operation with higher radiation gain and whose frequency ratio can be modified by simply adjusting the heights of the two magneto-electric dipole segments. This feature is necessary for cellular base-station applications. The operation and characteristics of the antenna are validated by measurements. The measured results confirm the proposed antenna achieves fractional bandwidths of 13.31% (801.9-916.2 MHz) and 19.76% (1710.7-2085.7 MHz) for S11 ≀-10 dB. It has stable unidirectional radiation patterns and optimum radiation gains of 9.2 dBi and 7.8 dBi at the first and second operating bands, respectively

    Study of tagging effects on surviving rate of Caspian trout (Salmo trutta caspius) fries before releasing to natural habitat

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    Study of tagging effects on survival rate of Caspian trout (Salmo trutta caspius) fries before releasing to natural habitat was a part of a large research plan on conservation and restoration of Caspian trout stocks in the Southern Caspian by Coldwater Fishes Research Center. Catching brooders, propagation, larvae and juvenile rearing were carried out in Southern coasts and rivers of Caspian sea and in shahid Bahonar propagation center in Kelardasht, Mazandaran (North of Iran) in autumn 2012. 150 fries for each treatment (5, 10 and 20 g fries and Plastic T tag, elastomer tag and control treatments) anesthetized, weighed (g), measured (mm), tagged, disinfected and introduced to cement ponds. Fries were kept and fed for 5 days and their behavior and responses to food, infection of wound and mortality were recorded. No mortality were observed in all treatments, fries were shocked for few hours after handling and did not take food but they started to feed from the first day after tagging and there was no infection in macroscopic observation of wound

    Complete Result for Positronium Energy Levels at Order alpha^6 m

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    We have completed theoretical predictions for positronium energy levels through order alpha^6 m by the calculation of the spin independent, radiative recoil correction. This contribution is significant and amounts to 10.64 MHz for the 1S state. We further perform detailed comparison of theoretical predictions to experimental results for 1S-2S and 2S-2P transitions.Comment: 9 pages, 2 tables. Email: [email protected]

    Comparison of non-invasive to invasive oxygenation ratios for diagnosing acute respiratory distress syndrome following coronary artery bypass graft surgery: a prospective derivation-validation cohort study

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    Objective: To determine if non-invasive oxygenation indices, namely peripheral capillary oxygen saturation (SpO2)/ fraction of inspired oxygen (Fi O2) and partial pressure of alveolar oxygen (PAO2)/Fi O2 may be used as effective surrogates for the partial pressure of arterial oxygen (PaO2)/Fi O2. Also, to determine the SpO2/Fi O2 and PAO2/Fi O2 values that correspond to PaO2/Fi O2 thresholds for identifying acute respiratory distress syndrome (ARDS) in patients following coronary artery bypass graft (CABG) surgery. Methods: A prospective derivation-validation cohort study in the Open-Heart ICU of an academic teaching hospital. Recorded variables included patient demographics, ventilator settings, chest radiograph results, and SPO2, PaO2, PAO2, SaO2, and Fi O2. Linear regression modeling was used to quantify the relationship between indices. Receiver operating characteristic (ROC) curves were used to determine the sensitivity and specificity of the threshold values. Results: One-hundred seventy-five patients were enrolled in the derivation cohort, and 358 in the validation cohort. The SPO2/Fi O2 and PAO2/Fi O2 ratios could be predicted well from PaO2/Fi O2, described by the linear regression models SPO2/Fi O2 = 71.149 + 0.8PF and PAO2/Fi O2 = 38.098 + 2.312PF, respectively. According to the linear regression equation, a PaO2/Fi O2 ratio of 300 equaled an SPO2/Fi O2 ratio of 311 (R2 0.857, F 1035.742, < 0.0001) and a PAO2/Fi O2 ratio of 732 (R2 0.576, F 234.887, < 0.0001). The SPO2/Fi O2 threshold of 311 had 90% sensitivity, 80% specificity, LR+ 4.50, LR- 0.13, PPV 98, and NPV 42.1 for the diagnosis of mild ARDS. The PAO2/Fi O2 threshold of 732 had 86% sensitivity, 90% specificity, LR+ 8.45, LR- 0.16, PPV 98.9, and NPV 36 for the diagnosis of mild ARDS. SPO2/ Fi O2 had excellent discrimination ability for mild ARDS (AUC ± SE = 0.92 ± 0.017; 95% CI 0.889 to 0.947) as did PAO2/ Fi O2 (AUC ± SE = 0.915 ± 0.018; 95% CI 0.881 to0.942). Conclusions: PaO2 and SaO2 correlated in the diagnosis of ARDS, with a PaO2/Fi O2 of 300 correlating to an SPO2/ Fi O2 of 311 (Sensitivity 90%, Specificity 80%). The SPO2/ Fi O2 ratio may allow for early real-time rapid identification of ARDS, while decreasing the cost, phlebotomy, blood loss, pain, skin breaks, and vascular punctures associated with serial arterial blood gas measurements

    Experimental progress in positronium laser physics

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