A simulating software of fetal phonocardiographic signals

A valuable alternative to traditional diagnostic tool to record fetal heart rate, to monitor the general fetal wellbeing, is fetal phonocardiography, a passive and low cost acoustic recording of fetal heart sounds. In this paper, it is presented a simulating software of fetal phonocardiographic signals relative to different fetal physiological states and recording conditions (for example different kinds and levels of noise). This software can be useful to test and assess fetal heart rate extraction algorithms from fetal phonocardiographic recordings and as a teaching tool for demonstration to medical students and others. © 2010 IEEE.

Fibre impairment compensation using artificial neural network equalizer for high-capacity coherent optical OFDM signals

We propose an artificial neural network (ANN) equalizer for transmission performance enhancement of coherent optical OFDM (C-OOFDM) signals. The ANN equalizer showed more efficiency in combating both chromatic dispersion (CD) and single-mode fibre (SMF)-induced non-linearities compared to the least mean square (LMS). The equalizer can offer a 1.5 dB improvement in optical signal-to-noise ratio (OSNR) compared to LMS algorithm for 40 Gbit/s C-OOFDM signals when considering only CD. It is also revealed that ANN can double the transmission distance up to 320 km of SMF compared to the case of LMS, providing a nonlinearity tolerance improvement of ∼0.7 dB OSNR.

All-optical add-drop multiplexing of OFDM signals

We discuss the recently proposed architecture for an all-optical add-drop multiplexer of OFDM signals and we summarize the results of its theoretical design and experimental implementation. © 2015 OSA.

Explaining turn of the year order flow imbalance

The paper provides evidence of a turn of the year effect in the order flow imbalance of both retail and institutional investors. In December there is net selling pressure which is reversed in January. We examine high frequency intraday order flow information and find that the changes in order flow imbalance between December and January are related to firm risk factors and characteristics. We find that retail order flow imbalances are associated with a wide range of risk characteristics including beta, illiquidity and unsystematic risk. Imbalances in institutional order flow are associated with only a small number of risk variables. We show that these order flow changes are important because risk premiums are elevated in January. Our results are robust to the effects of decimalization.

Direction Finding Estimators of Cyclostationary Signals in Array Processing for Microwave Power Transmission

A solar power satellite is paid attention to as a clean, inexhaustible large- scale base-load power supply. The following technology related to beam control is used: A pilot signal is sent from the power receiving site and after direction of arrival estimation the beam is directed back to the earth by same direction. A novel direction-finding algorithm based on linear prediction technique for exploiting cyclostationary statistical information (spatial and temporal) is explored. Many modulated communication signals exhibit a cyclostationarity (or periodic correlation) property, corresponding to the underlying periodicity arising from carrier frequencies or baud rates. The problem was solved by using both cyclic second-order statistics and cyclic higher-order statistics. By evaluating the corresponding cyclic statistics of the received data at certain cycle frequencies, we can extract the cyclic correlations of only signals with the same cycle frequency and null out the cyclic correlations of stationary additive noise and all other co-channel interferences with different cycle frequencies. Thus, the signal detection capability can be significantly improved. The proposed algorithms employ cyclic higher-order statistics of the array output and suppress additive Gaussian noise of unknown spectral content, even when the noise shares common cycle frequencies with the non-Gaussian signals of interest. The proposed method completely exploits temporal information (multiple lag ), and also can correctly estimate direction of arrival of desired signals by suppressing undesired signals. Our approach was generalized over direction of arrival estimation of cyclostationary coherent signals. In this paper, we propose a new approach for exploiting cyclostationarity that seems to be more advanced in comparison with the other existing direction finding algorithms.

All-optical add-drop multiplexer for OFDM signals

We summarize our research work on the design and development of an add-drop multiplexer for spectrally overlapping OFDM signals. The standard node functions of sub-channel drop, extraction and insertion were obtained whilst the signals remained fully in the optical domain. Numerical simulations have been carried out to identify the main sources of degradation and to benchmark the architectural performance against critical design parameters, whereas the experimental demonstration of the scheme has been achieved for both single quadrature and dual quadrature signals. The reported scheme enables a fully flexible node compatible with future terabit per second super-channel transmission.

Accent Recognition for Noisy Audio Signals

It is well established that accent recognition can be as accurate as up to 95% when the signals are noise-free, using feature extraction techniques such as mel-frequency cepstral coefficients and binary classifiers such as discriminant analysis, support vector machine and k-nearest neighbors. In this paper, we demonstrate that the predictive performance can be reduced by as much as 15% when the signals are noisy. Specifically, in this paper we perturb the signals with different levels of white noise, and as the noise become stronger, the out-of-sample predictive performance deteriorates from 95% to 80%, although the in-sample prediction gives overly-optimistic results. ACM Computing Classification System (1998): C.3, C.5.1, H.1.2, H.2.4., G.3.

Numerical investigation of all-optical add-drop multiplexing for spectrally overlapping OFDM signals

We propose a novel architecture for all-optical add-drop multiplexing of OFDM signals. Sub-channel extraction is achieved by means of waveform replication and coherent subtraction from the OFDM super-channel. Numerical simulations have been carried out to benchmark the performance of the architecture against critical design parameters.

Two cascaded SOAs used as intensity modulators for adaptively modulated optical OFDM signals in optical access networks

Detailed theoretical and numerical investigations of the transmission performance of adaptively modulated optical orthogonal frequency division multiplexed (AMOOFDM) signals are undertaken, for the first time, in optical amplification and chromatic dispersion (CD) compensation free single mode fiber (SMF) intensity-modulated and directdetection (IMDD) systems using two cascaded semiconductor optical amplifiers in a counterpropagating configuration as an intensity modulator (TC-SOA-CC-IM). A theoretical model describing the characteristics of this configuration is developed. Extensive performance comparisons are also made between the TC-SOA-CC and the single SOA intensity modulators. It is shown that, the TC-SOA-CC reaches its strongly saturated region using a lower input optical power much faster than the single SOA resulting in significantly reduced effective carrier lifetime and thus wide TC-SOA-CC bandwidths. It is shown that at low input optical power, we can increase the signal line rate almost 115% which will be more than twice the transmission performance offered by single SOA. In addition, the TCSOA-CC-IM is capable of supporting signal line rates higher than corresponding to the SOA-IM by using 10dB lower input optical powers. For long transmission distance, the TC-SOA-CC-IM has much stronger CD compensation capability compared to the SOA-IM. In addition the use of TC-SOA-CC-IM is more effective regarding the capability to benefit from the CD compensation for shorter distances starting at 60km SMF, whilst for the SOA-IM starting at 90km. © 2014 Optical Society of America.

The development of attenuation compensation models of fluorescence spectroscopy signals

This study examines the effect of blood absorption on the endogenous fluorescence signal intensity of biological tissues. Experimental studies were conducted to identify these effects. To register the fluorescence intensity, the fluorescence spectroscopy method was employed. The intensity of the blood flow was measured by laser Doppler flowmetry. We proposed one possible implementation of the Monte Carlo method for the theoretical analysis of the effect of blood on the fluorescence signals. The simulation is constructed as a four-layer skin optical model based on the known optical parameters of the skin with different levels of blood supply. With the help of the simulation, we demonstrate how the level of blood supply can affect the appearance of the fluorescence spectra. In addition, to describe the properties of biological tissue, which may affect the fluorescence spectra, we turned to the method of diffuse reflectance spectroscopy (DRS). Using the spectral data provided by the DRS, the tissue attenuation effect can be extracted and used to correct the fluorescence spectra.

Hungary's U-Turn

For two decades Hungary, like the other Eastern European countries, followed a general policy of establishing and strengthening the institutions of democracy, rule of law, and a market economy based on private property. However, since the elections of 2010, when Viktor Orbán's Fidesz party came to power, Hungary has made a dramatic U-turn. This article investigates the different spheres of society: political institutions, the rule of law, and the influence of state and market on one another, as well as the world of ideology (education, science and art), and describes the U-turn’s implications for these fields and the effect it has on the life of people. It argues against the frequent misunderstandings in the interpretation and evaluation of the Hungarian situation, pointing out some typical intellectual fallacies. It draws attention to the dangers of strengthening nationalism, and to the ambivalence evident in Hungarian foreign policy, and looks into the relationship between Hungary and the Western world, particularly the European Union. Finally, it outlines the possible scenarios resulting from future developments in the Hungarian situation.

Hungary's U-Turn

For two decades Hungary, like the other Eastern European countries, followed a general policy of establishing and strengthening the institutions of democracy, rule of law, and a market economy based on private property. However, since the elections of 2010, when Viktor Orbán's Fidesz party came to power, Hungary has made a dramatic U-turn. This article investigates the different spheres of society: political institutions, the rule of law, and the influence of state and market on one another, as well as the world of ideology (education, science and art), and describes the U-turn's implications for these fields and the effect it has on the life of people. It argues against the frequent misunderstandings in the interpretation and evaluation of the Hungarian situation, pointing out some typical intellectual fallacies. It draws attention to the dangers of strengthening nationalism, and to the ambivalence evident in Hungarian foreign policy, and looks into the relationship between Hungary and the Western world, particularly the European Union. Finally, it outlines the possible scenarios resulting from future developments in the Hungarian situation.

Hungary's U-Turn

For two decades Hungary, like the other Eastern European countries, followed a general policy of establishing and strengthening the institutions of democracy, rule of law, and a market economy based on private property. However, since the elections of 2010, when Viktor Orbán's Fidesz party came to power, Hungary has made a dramatic U-turn. This article investigates the different spheres of society: political institutions, the rule of law, and the influence of state and market on one another, as well as the world of ideology (education, science and art), and describes the U-turn’s implications for these fields and the effect it has on the life of people. It argues against the frequent misunderstandings in the interpretation and evaluation of the Hungarian situation, pointing out some typical intellectual fallacies. It draws attention to the dangers of strengthening nationalism, and to the ambivalence evident in Hungarian foreign policy, and looks into the relationship between Hungary and the Western world, particularly the European Union. Finally, it outlines the possible scenarios resulting from future developments in the Hungarian situation.

Why Leaves Turn Red in Autumn. The Role of Anthocyanins in Senescing Leaves of Red-Osier Dogwood

Why the leaves of many woody species accumulate anthocyanins prior to being shed has long puzzled biologists because it is unclear what effects anthocyanins may have on leaf function. Here, we provide evidence for red-osier dogwood (Cornus stolonifera) that anthocyanins form a pigment layer in the palisade mesophyll layer that decreases light capture by chloroplasts. Measurements of leaf absorbance demonstrated that red-senescing leaves absorbed more light of blue-green to orange wavelengths (495–644 nm) compared with yellow-senescing leaves. Using chlorophyll a fluorescence measurements, we observed that maximum photosystem II (PSII) photon yield of red-senescing leaves recovered from a high-light stress treatment, whereas yellow-senescing leaves failed to recover after 6 h of dark adaptation, which suggests photo-oxidative damage. Because no differences were observed in light response curves of effective PSII photon yield for red- and yellow-senescing leaves, differences between red- and yellow-senescing cannot be explained by differences in the capacities for photochemical and non-photochemical light energy dissipation. A role of anthocyanins as screening pigments was explored further by measuring the responses PSII photon yield to blue light, which is preferentially absorbed by anthocyanins, versus red light, which is poorly absorbed. We found that dark-adapted PSII photon yield of red-senescing leaves recovered rapidly following illumination with blue light. However, red light induced a similar, prolonged decrease in PSII photon yield in both red- and yellow-senescing leaves. We suggest that optical masking of chlorophyll by anthocyanins reduces risk of photo-oxidative damage to leaf cells as they senesce, which otherwise may lower the efficiency of nutrient retrieval from senescing autumn leaves.