Evaluation of Instrumental Errors Built in Circular Dichroism Spectrometers

Because of the increased use of circular dichroism (CD) spectroscopy as a routine technique by nonspecialists to determine the conformational/configurational properties of biomolecules, we have decided to present here some criteria to accurately check the ordinate scale calibration of a CD spectrometer particularly in the critical lowwavelength UV region, to understand, and correct, where possible, the potential limitations coming from the hardware. We also analyze some wavelength calibration methods, and some standards for the CD-scale calibration, and we discuss the critical characteristics of current instrumentation affecting measurements. The example of the bovine catalase CD spectrum is considered

Partnership Communities

We undertake the first quantitative and broadly comparative study of the structure and performance of partnership communities to our knowledge. Our study addresses several important research questions. How connected are the members of partnership communities? How can we understand the quality of the projects a community undertakes? How do political institutions shape their structure and performance? After defining partnership communities as networked communities of private firms which form the consortia that enter into long-term contractual arrangements with governments, we show how they are affected by government demand for partners. We then provide an overview of those factors predicting success in financing projects. Finally, we focus on the political economy of partnership communities. We develop and test theoretical predictions about how national institutions shape partnership communities and the quality of projects. We also investigate voters' preferences over alternative arrangements of infrastructure delivery before drawing out implications for research and practice

Alterations of cardiovascular complexity during acute exposure to high altitude: A multiscale entropy approach

Stays at high altitude induce alterations in cardiovascular control and are a model of specific pathological cardiovascular derangements at sea level. However, high-altitude alterations of the complex cardiovascular dynamics remain an almost unexplored issue. Therefore, our aim is to describe the altered cardiovascular complexity at high altitude with a multiscale entropy (MSE) approach. We recorded the beat-by-beat series of systolic and diastolic blood pressure and heart rate in 20 participants for 15 min twice, at sea level and after arrival at 4554 m a.s.l. We estimated Sample Entropy and MSE at scales of up to 64 beats, deriving average MSE values over the scales corresponding to the high-frequency (MSEHF) and low-frequency (MSELF) bands of heart-rate variability. We found a significant loss of complexity at heart-rate and blood-pressure scales complementary to each other, with the decrease with high altitude being concentrated at Sample Entropy and at MSEHF for heart rate and at MSELF for blood pressure. These changes can be ascribed to the acutely increased chemoreflex sensitivity in hypoxia that causes sympathetic activation and hyperventilation. Considering high altitude as a model of pathological states like heart failure, our results suggest new ways for monitoring treatments and rehabilitation protocols

Multi-wavelength SPAD photoplethysmography for cardio-respiratory monitoring

There is a growing interest in photoplethysmography (PPG) for the continuous monitoring of cardio-respiratory signals by portable instrumentation aimed at the early diagnosis of cardiovascular diseases. In this context, it is conceivable that PPG sensors working at different wavelengths simultaneously can optimize the identification of apneas and the quantification of the associated heart-rate changes or other parameters that depend on the PPG shape (e.g., systematic vascular resistance and pressure), when evaluating the severity of breathing disorders during sleep and in general for health monitoring. Therefore, the objective of this work is to present a novel pulse oximeter that provides synchronous data logging related to three light wavelengths (green, red, and infrared) in transmission mode to optimize both heart rate measurements and a reliable and continuous assessment of oxygen saturation. The transmission mode is considered more robust over motion artifacts than reflection mode, but current pulse oximeters cannot employ green light in transmission mode due to the high absorbance of body tissues at this wavelength. For this reason, our device is based on a Single-Photon Avalanche Diode (SPAD) with very short deadtime (less than 1 ns) to have, at the same time, the single photon sensitivity and high-count rate that allows acquiring all the wavelengths of interest on the same site and in transmission mode. Previous studies have shown that SPAD cameras can be used for measuring the heart rate through remote PPG, but oxygen saturation and heart-rate measures through contact SPAD-based PPG sensors have never been addressed so far. The results of the preliminary validation on six healthy volunteers reflect the expected physiological phenomena, providing rms errors in the Inter Beat Interval estimation smaller than 70 ms (with green light) and a maximum error in the oxygen saturation smaller than 1% during the apneas. Our prototype demonstrates the reliability of SPAD-based devices for continuous long-term monitoring of cardio-respiratory variables as an alternative to photodiodes especially when minimal area and optical power are required

Complexity analysis of surface electromyography for assessing the myoelectric manifestation of muscle fatigue: A review

The surface electromyography (sEMG) records the electrical activity of muscle fibers during contraction: one of its uses is to assess changes taking place within muscles in the course of a fatiguing contraction to provide insights into our understanding of muscle fatigue in training protocols and rehabilitation medicine. Until recently, these myoelectric manifestations of muscle fatigue (MMF) have been assessed essentially by linear sEMG analyses. However, sEMG shows a complex behavior, due to many concurrent factors. Therefore, in the last years, complexity-based methods have been tentatively applied to the sEMG signal to better individuate the MMF onset during sustained contractions. In this review, after describing concisely the traditional linear methods employed to assess MMF we present the complexity methods used for sEMG analysis based on an extensive literature search. We show that some of these indices, like those derived from recurrence plots, from entropy or fractal analysis, can detect MMF efficiently. However, we also show that more work remains to be done to compare the complexity indices in terms of reliability and sensibility; to optimize the choice of embedding dimension, time delay and threshold distance in reconstructing the phase space; and to elucidate the relationship between complexity estimators and the physiologic phenomena underlying the onset of MMF in exercising muscles

Microarray analyses to identify differentially expressed genes for assessing meat quality in swine

In order to identify candidate genes and molecular mechanisms that influence meat quality and production in pigs, microarray experiments were carried out to find differences in gene expression levels between two pools of six individuals, constituting the extreme tails of the Gaussian distribution of seven adjusted phenotypes of 100 Landrace and Large White animals. The phenotypes considered in this study were: muscle compactness, marbling, colour uniformity, fat covering, colour, dorsal fat, thickness, ham fat thickness. 437 differentially expressed ESTs (Expressed Sequence Tags) were found, clustering in different pathways according to their ontology. In particular, 73 functional categories were identified and ten of them could have a role in meat quality. Among the ESTs belonging to these pathways, seven of them were selected to be validated in quantitative real-time RT-PCR