Phase Noise Compensation for Nonlinearity-Tolerant Digital Subcarrier Systems With High-Order QAM

The fundamental penalty of subcarrier modulation (SCM) with independent subcarrier phase noise processing is estimated. It is shown that the fundamental signal-to-noise ratio (SNR) penalty related to poorer phase noise tolerance of decreased baudrate subcarriers increases significantly with modulation format size and can potentially exceed the gains of the nonlinear tolerance of SCM. A low-complexity algorithm is proposed for joint subcarrier phase noise processing, which is scalable in the number of subcarriers and recovers almost entirely the fundamental SNR penalty with respect to single-carrier systems operating at the same net data-rate. The proposed algorithm enables high-order modulation formats with high count of subcarriers to be safely employed for nonlinearity mitigation in optical communication systems

Machine learning aided carrier recovery in continuous-variable quantum key distribution

The secret key rate of a continuous-variable quantum key distribution (CV-QKD) system is limited by excess noise. A key issue typical to all modern CV-QKD systems implemented with a reference or pilot signal and an independent local oscillator is controlling the excess noise generated from the frequency and phase noise accrued by the transmitter and receiver. Therefore accurate phase estimation and compensation, so-called carrier recovery, is a critical subsystem of CV-QKD. Here, we explore the implementation of a machine learning framework based on Bayesian inference, namely an unscented Kalman filter (UKF), for estimation of phase noise and compare it to a standard reference method. Experimental results obtained over a 20 km fibre-optic link indicate that the UKF can ensure very low excess noise even at low pilot powers. The measurements exhibited low variance and high stability in excess noise over a wide range of pilot signal to noise ratios. This may enable CV-QKD systems with low implementation complexity which can seamlessly work on diverse transmission lines.Comment: 7 pages, 10 figure

Development of Prezi-Based KOH Link Learning Media in Elementary School Science Lessons

The background of this research is because the Prezi application-based KOH Link learning media has not yet been developed in science learning. In the learning process, the teacher already uses learning media but is less creative, while at school the facilities and infrastructure are adequate, such as LCD projectors. This study aims to determine the process of developing prezi-based KOH Link learning media products, to determine the level of effectiveness of learning media. This type of research is research and development (research and development) of the Four-D model which consists of defining, designing, developing, and disseminating. Data collection techniques are carried out by carrying out effectiveness. Data analysis techniques are performed by calculating the average value of the results of effectiveness. The results showed that classical completeness was 81.48% with very good criteria and student responses obtained an average of 3.7 with very positive criteria. Thus, it can be concluded that the Prezi-based KOH Link learning media in classifying animals based on the type of food is very effective as one of the media in science subjects

The role of stress in heart failure – ground for sex specific pathophysiology

In the last hundred years modern society went through numerous changes in life style, dietary habits, work load, physical activity and other environmental factors. As a species we are not well adapted to new demands. Higher levels of stress hormones provoke various effects, especially gradual change in the sensitivity of adrenergic, glucocorticoid and insulin receptors. All these changes are mutually associated and they gradually lead to metabolic syndrome, obesity, diabetes, heart failure and other types of pathology depending on genetic makeup and environmental factors. The aim of this paper is to summarize current knowledge concerning the impact of stress on cardiac function. Whereas stress response is sex specific we would emphasize a potential difference in pathophysiology of ischemic heart failure in men and women. Modern medicine has misinterpreted autonomous nervous system functions for years and this was reflected in heart failure (HF) and arterial hypertension therapy. Stress before the onset of menopause has a lesser effect on cardiac function compared to stress after menopause. Postmenopausal women have a significantly higher risk of heart disease, which is related to the diminished protection of the female hormonal cycle, but low doses of estrogen have not proven protective in postmenopausal women. Potential new targets of sexspecific cardiac therapy would come from better understanding of the molecular mechanisms exerted by nuclear receptors for steroid hormones, transcription factors involved in heart remodeling, cross-talk in adrenergic signaling pathways and their down-stream molecules. Keywords: heart failure, stress, adrenergic receptors, sex specific.За останнє століття сучасне суспільство зазнало багаточисельних змін у способі життя (звичках, харчуванні, навантаженнях, фізичній активності), а також під впливом чинників довкілля. Як біологічний вид ми не дуже добре адаптувалися до нових умов. Вищі рівні гормонів стресу спричиняють різні ефекти, поступово змінюється чутливість адренергічних, глюкокортикоїдних і інсулінових рецепторів. Усі ці зміни взаємопов’язані і залежно від генетичних і екологічних факторів призводять до таких метаболічних синдромів, як ожиріння, цукровий діабет, серцева недостатність тощо. Оскільки відповідь на стрес залежить і від статі, потрібно враховувати можливу різницю у патофізіології серцевої недостатності у чоловіків і жінок. Протягом багатьох років функції вегетативної нервової системи невірно трактувалися сучасною медициною, що відбилося на терапії серцевої недостатності і гіпертензії. Вплив стресу на серцеву функцію у перід до і після менопаузи різниться. У жінок у постменопаузі значно підвищується ризик серцево-судинних захворювань, який визначається зниженням захисної функції жіночого гормонального циклу. Глибше вивчення молекулярних механізмів дії ядерних рецепторів стероїдних гормонів, факторів транскрипції, які беруть участь у ремоделюванні серця, перехресних адренергічних сигнальних шляхів та їхніх ефекторних молекул призведе до постановки нових задач для гендер-специфічної терапії. Ключові слова: серцева недостатність, стрес, адренергічні рецептори, статева специфічність.За последнее столетие современное общество претерпело многочисленные изменения в образе жизни (привычках, способе питании, нагрузках, физической активности), а также под влиянием факторов окружающей среды. Как биологический вид мы не очень хорошо адаптировались к новым условиям. Более высокие уровни гормонов стресса приводят к различным эффектам, постепенно меняется чувствительность адренергических, глюкокортикоидных и инсулиновых рецепторов. Все эти изменения взаимосвязаны и в зависимости от генетической и экологических факторов приводят к таким метаболическим синдромам, как ожирение, сахарный диабет, сердечная недостаточность и др. Поскольку ответ на стресс зависит и от пола, нужно учитывать возможную разницу в патофизиологии сердечной недостаточности у мужчин и женщин. В течение многих лет функции вегетативной нервной системы неверно трактовались современной медициной, что отразилось на терапии сердечной недостаточности и гипертензии. Влияние стресса на сердечную функцию в период до и после менопаузы различается. У женщин в постменопаузе значительно повышается риск сердечно-сосудистых заболеваний, определяемый снижением защитной функции женского гормонального цикла. Более углубленное изучение молекулярных механизмов действия ядерных рецепторов стероидных гормонов, факторов транскрипции, участвующих в ремоделировании сердца, перекрестных адренергических сигнальных путей и их эффекторных молекул приведет к постановке новых задач для гендер-специфической терапии. Ключевые слова: сердечная недостаточность, стресс, адренергические рецепторы, половая специфичность

Multi-Band Programmable Gain Raman Amplifier

Optical communication systems, operating in C-band, are reaching their theoretically achievable capacity limits. An attractive and economically viable solution to satisfy the future data rate demands is to employ the transmission across the full low-loss spectrum encompassing O, E, S, C, and L band of the single mode fibers (SMF). Utilizing all five bands offers a bandwidth of up to sim53.5 THz (365 nm) with loss below 0.4 dB/km. A key component in realizing multi-band optical communication systems is the optical amplifier. Apart from having an ultra-wide gain profile, the ability of providing arbitrary gain profiles, in a controlled way, will become an essential feature. The latter will allow for signal power spectrum shaping which has a broad range of applications such as the maximization of the achievable information rate × distance product, the elimination of static and lossy gain flattening filters (GFF) enabling a power efficient system design, and the gain equalization of optical frequency combs. In this paper, we experimentally demonstrate a multi-band (S+C+L) programmable gain optical amplifier using only Raman effects and machine learning. The amplifier achieves >1000 programmable gain profiles within the range 3.5 to 30 dB, in an ultra-fast way and a very low maximum error of 1.6 cdot 10{-2} dB/THz over an ultra-wide bandwidth of 17.6-THz (140.7-nm)

Low-complexity BCH codes with optimized interleavers for DQPSK systems with laser phase noise

The presence of high phase noise in addition to additive white Gaussian noise in coherent optical systems affects the performance of forward error correction (FEC) schemes. In this paper, we propose a simple scheme for such systems, using block interleavers and binary Bose–Chaudhuri–Hocquenghem (BCH) codes. The block interleavers are specifically optimized for differential quadrature phase shift keying modulation. We propose a method for selecting BCH codes that, together with the interleavers, achieve a target post-FEC bit error rate (BER). This combination of interleavers and BCH codes has very low implementation complexity. In addition, our approach is straightforward, requiring only short pre-FEC simulations to parameterize a model, based on which we select codes analytically. We aim to correct a pre-FEC BER of around (Formula presented.). We evaluate the accuracy of our approach using numerical simulations. For a target post-FEC BER of (Formula presented.), codes selected using our method result in BERs around 3(Formula presented.) target and achieve the target with around 0.2 dB extra signal-to-noise ratio

Current preventive strategies and management of Epstein-Barr virus-related post-transplant lymphoproliferative disease in solid organ transplantation in Europe. Results of the ESGICH Questionnaire-based Cross-sectional Survey

There is limited clinical evidence on the utility of the monitoring of Epstein-Barr virus (EBV) DNAemia in the pre-emptive management of post-transplant lymphoproliferative disease (PTLD) in solid organ transplant (SOT) recipients. We investigated current preventive measures against EBV-related PTLD through a web-based questionnaire sent to 669 SOT programmes in 35 European countries. This study was performed on behalf of the ESGICH study group from the European Society of Clinical Microbiology and Infectious Diseases. A total of 71 SOT programmes from 15 European countries participated in the study. EBV serostatus of the recipient is routinely obtained in 69/71 centres (97%) and 64 (90%) have access to EBV DNAemia assays. EBV monitoring is routinely used in 85.9% of the programmes and 77.4% reported performing pre-emptive treatment for patients with significant EBV DNAemia levels. Pre-emptive treatment for EBV DNAemia included reduction of immunosuppression in 50.9%, switch to mammalian target of rapamycin inhibitors in 30.9%, and use of rituximab in 14.5% of programmes. Imaging by whole-body 18-fluoro-deoxyglucose positron emission tomography (FDG-PET) is used in 60.9% of centres to rule out PTLD and complemented computer tomography is used in 50%. In 10.9% of centres, FDG-PET is included in the first-line diagnostic workup in patients with high-risk EBV DNAemia. Despite the lack of definitive evidence, EBV load measurements are frequently used in Europe to guide diagnostic workup and pre-emptive reduction of immunosuppression. We need prospective and controlled studies to define the impact of EBV monitoring in reducing the risk of PTLD in SOT recipients