Academic literature on the topic 'PPG'

La fotopletismografia (PPG) è una tecnica recente per la misura del volume del sangue arterioso basata sullo studio della variazione dell'assorbanza fra emoglobina ossigenata e deossigenata. I suoi vantaggi sono la semplicità dell'apparato, il basso costo e la non invasività. L'età biologica di un individuo è determinata non solo dall'età cronologica, ma anche da altri fattori come lo stile di vita, possibili patologie, dieta, esercizio fisico, stress. Lo studio dell'età biologica è quindi importante per la possibilità di diagnosticare possibili malattie o problemi con il proprio stile di vita. In questa tesi svilupperemo diversi modelli di machine learning e reti neurali per la regressione dell'età biologica utilizzando delle features estratte da un dataset di segnali PPG. La quantità di sangue che transita nel sistema vascolare dipende infatti dal tono vascolare e questo a sua volta dipende dall'età del soggetto.

Poly(urethane)s and poly(urethane-urea)s (PUU) are nearly ubiquitous, having been in existence since before the Second World War. Spandex, a poly(urethane-urea) elastomeric fiber, is found in nearly all articles of apparel as well as in an increasing array of other consumer items. The technology and chemistry of spandex is largely unchanged since its inception in the late 1950s, with the majority of spandex employing poly(tetramethylene ether glycol) as soft segments. Recent developments in catalyst technology have resulted in the production of ultra-low monol content poly(propylene glycol) (PPG), which is nearly difunctional (f=1.95+). This enhancement in difunctionality has potentially enabled the use of PPG as a spandex soft segment with potential spandex processing, performance, and economic benefits. PPG-based spandex elastomers were evaluated in both film and fiber form for the purpose of investigating morphological, orientational, mechanical, and thermal properties with the goal of understanding relationships between chemistry, morphology and properties. Key variables of interest were soft segment molecular weight (MW), molecular weight distribution (MWD), and composition, and hard segment content and composition. Of those, the influence of the molecular weight distribution of the polyol used for soft segments was of foremost interest and had previously been largely neglected during the course of poly(urethane) and poly(urethane-urea) research. It was found that over the range of PUU compositions suitable for production of spandex, that hard segment content and composition had little effect upon the morphology and thermal and mechanical properties. Appreciable trends as functions of soft segment molecular weight were observed. The soft segment MWD was adjusted through the addition of a low molecular weight homolog of PPG, tri(propylene glycol) (TPG), decreasing the number average soft segment MW. The results of these experiments were contrary to those for variation of soft segment molecular weight. It was determined that the low MW portion of the polyol MWD contributes to the building of hard segments in addition to or in lieu of soft segments. Incorporation of TPG in the PUUs resulted in larger, presumably less cohesive, hard domains and increased hard segment content. The TPG containing materials had enhanced tensile properties, less permanent set, and less residual orientation after deformation. These materials proved quite comparable to those using PTMEG soft segments. Comparison of film and fiber PUUs revealed only minor differences, implying that the trends and conclusions drawn from the study of films with spandex-like compositions would also hold for fibers. The key difference between films and fibers is that fibers maintain some residual ordering and orientation due to drawing of the fibers during processing. Of the processing variables investigated, none impacted the morphology as determined from small angle x-ray scattering. It was concluded, that of the various compositional variables germane to spandex, the polyol MW and MWD played key roles in development of morphology, and hence properties. The role of polyol MWD had been woefully neglected during the development of spandex previously, and was observed to be a critical variable.<br>Ph. D.

<p> A laboratory scale plating cell was built that provided reproducible bottom-up fill results for the electrochemical deposition of copper in damascene features. Several techniques used in the full wafer plating tool were incorporated into the setup to accurately control the process conditions. These techniques included but were not limited to a voltage controlled `hot-entry' step, a custom coupon holder to allow sample rotation, a secondary thief electrode and an automatic entry system. The results of qualification experiments are presented to demonstrate that precise control was realized along with repeatable partial fill plating results. The qualified setup was then used to perform time-evolved partial fill plating experiments using several different structural configurations of open-source suppressors to investigate their affect on the gap-fill characteristics. </p><p> Common open-source suppressors used for copper filling of damascene interconnects include polyethylene glycol (PEG), polypropylene glycol (PPG), or a copolymer structure of both. Differences in the configuration and structure of these suppressors generate variations in polarization strength, surface adsorption rate, and SPS displacement rate. These properties were measured by electrochemical transient analysis and coupled with the results of time-evolved partial fill plating experiments to determine the effect of electrochemical property variations on the gap-fill characteristics. The high polarization strength of PPG, along with its greater dependence on concentration was found to greatly increase the bottom-up growth rate during copper filling, while the improved resistance to accelerator displacement of PEG resulted in better sidewall protection. Both these gap-fill characteristics were evident when PEG and PPG were combined together as a mixture of separate homopolymers or in copolymer structures, although the overall influence was dependent on the size and configuration of each component. These data sets provided a more fundamental understanding of PEG, PPG and their different configurations role in the metallization of damascene interconnects. These data can also be used to infer the relative gap-fill performance to screen new suppressor candidates and reduce the quantity of plating experiments by comparison of the electrochemical properties.</p>

The field of app-based PPG monitoring of cardiac activity is promising, yet classification of heart rhythms in normal sinus rhythm (NSR) or atrial fibrillation (Afib) is difficult in the case of noisy measurements. In this work, we aim at characterizing a dataset of 1572 subjects, whose signals have been crowdsourced by collecting measurements via a dedicated smartphone app, using the embedded camera. We evaluate the distributions of three features of our signals: the peak area, amplitude and the time interval between two successive pulses. We evaluate if some factors affected the distributions, discovering that the strongest effects are for age and BMI groupings. We evaluate the results agreement between the R G B channels of acquisition, finding good agreement between the first two. After finding signal quality indexes in literature, we use a subset of them in a classification task, combined with dynamic time warping distance, a technique that matches a signal to a template. We achieve an accuracy of 89% on the test set, for binary quality classification. On the chaotic temporal series we evaluate the appearance of different types of rhythms on Poincaré plots and we quantify the results by a measure of their 3D spread. We perform this on a set of 20 subjects, 10 NSR and 10 Afib, finding significant differences between their 3D morphologies. We extend our analysis to the larger dataset, obtaining some significant results.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>73<br>Cataloged from student-submitted PDF version of thesis.<br>Includes bibliographical references (pages 149-155).<br>This work presents a wearable congestive heart failure (CHF) monitor at the ear that uses the ballistocardiogram (BCG), electrocardiogram (ECG), and photoplethysmogram (PPG) to extract mean blood pressure up the Carotid Artery. Being a natural anchoring point, the ear is demonstrated as a viable location for the integrated sensing of physiological signals. The BCG is obtained with an accelerometer, the ECG is taken in a single lead configuration, with one electrode at the mastoid and one on the back of the neck, and the PPG is measured by reflecting light off of the mastoid region above Reid's baseline. When the BCG and PPG are used together, a time delay of the blood pulse wave can be obtained, known as the pulse transit time (PTT), from a single site of measurement. The ear-worn device is wirelessly connected to a computer for real-time data recording. A clinical test involving hemodynamic maneuvers is performed on 15 subjects. The results demonstrate a linear relationship between mean blood pressure and ln(1/PTT ). Using amplitude information from the BCG signal allows for improving the accuracy of the PTT-to-BP algorithm without additional sensors. While the clinical device uses commercial components, a custom integrated circuit for reflectance-mode PPG is designed with the goal of removing static and time-varying interferers while minimizing power consumption and device size. The chip nominally consumes 425[mu]W and only requires LEDs and photodiodes to operate, replacing 7 chips and a MATLAB program compared to the discrete version. The circuit architecture leverages analog and digital techniques to remove up to 100[mu]A of static interferers and attenuate time-varying interferers by 87dB.<br>by Eric S. Winokur.<br>Ph. D.

Orientador: Leila da Costa Ferreira<br>Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Filosofia e Ciencias Humanas<br>Made available in DSpace on 2018-08-03T16:37:44Z (GMT). No. of bitstreams: 1 Silva_AlbertoLuizTeixeirada_D.pdf: 13402835 bytes, checksum: f8330aeb6ae1d6f22c68d11ca3c36ae0 (MD5) Previous issue date: 2003<br>Doutorado

Photoplethysmography is an optical technique for measuring the perfusion of blood in skin and tissue arterial vessels. Due to its simplicity, accessibility and abundance of information on an individual’s cardiovascular system, it has been a pervasive topic of research within recent years. With these benefits however there are many challenges concerning the processing and conditioning of the signal in order to allow information to be extracted. One such challenge is removing the baseline drift of the signal, which is caused by respiratory rate, muscle tremor and physiological changes within the body as a response to various stimuli. Over the years there have been many methods developed in order to condition the signal such as Wavelet Transform, Cubic Spline Interpolation, Morphological Operators and Fourier-Based filtering techniques. All have their own individual benefits and drawbacks. These drawbacks are that they are unsuitable for real-time usage due to the computation power needed, or have the trade-off of being real-time at the cost of deforming the signal which is unideal for accurate analysis. This thesis aims to explore these techniques in order to develop an algorithm that can be used to condition the signal against the baseline drift in real-time, while being able to achieve good computational efficiency and the preservation of the signal form.

Penile plethysmography is amongst the best measures for prediction of sexual recidivism and has been extensively researched. However, there are a variety of criticisms regarding use of penile plethysmography (PPG), including financial investment, significant training needs, lack of standardization, intrusive nature of the measure, extensive time for testing, and inability to use PPG with all groups of sexual offenders (e.g., women and adolescents). Viewing time has been studied, though not as extensively as PPG, regarding detection of sexual interest. This study examined the relationship between Monarch 21 PPG and Affinity viewing time variables, including responses to individual stimuli, a sex deviance differential, and a sex deviance ratio. It was predicted that there would be a significant positive correlation between key variables of the Monarch 21 PPG and Affinity. Overall, the associations found between the Monarch 21 PPG and the Affinity were significant, although the magnitudes of the associations were modest. When considering sexual deviance ratios and differentials (as is typically utilized in PPG literature), there was a small, but significant association between the Monarch 21 PPG and the Affinity. Consequently, it is recommended that more research be done comparing these two sets of measures, further evaluating the Affinity and its' predictive validity, and examining the complex arousal pattern shapes, rather than focusing only on a series of discrete variables.

Cette thèse s’intéresse aux systèmes d’authentification continue basés sur les signaux cardiaques, et plus précisément du signal PPG. Ce dernier est très largement utilisé dans les montres connectées et équipements médicaux, et son usage principal est de mesurer la fréquence cardiaque ainsi que le taux d’oxygène dans le sang.Cependant, ce signal est suffisamment précis et complexe pour différencier les individus et créer un nouveau système d’authentification. La mesure de ce signal en continu est déjà largement répandue au sein des populations, ainsi il paraît logique de chercher à l’utiliser pour créer un système d’authentification continue.Afin de créer un tel système, nous avons d’abord effectué un état de l’art. Ce dernier a mis en lumière divers biais méthodologiques au sein de la communauté. L’identification de ces derniers nous a poussés à créer un nouveau système de comparaison ainsi qu’une nouvelle méthode d’analyse des résultats. Nous avons ainsi testé et comparé plus de 250 modèles d’intelligence artificielle capables de reconnaître des individus à l’aide de leurs battements de cœur.Puis, nous avons créé un premier système d’authentification continue basé sur le signal PPG et étudié diverses attaques par corruption. Cette étude nous a permis de déterminer certaines failles de l’apprentissage continu.Enfin, nous avons déterminé une nouvelle méthode pour paramétrer de manière optimale un système d’authentification continue. Cette procédure permet de maximiser l’ergonomie de chaque utilisateur pour un niveau de sécurité défini<br>This thesis focuses on continuous authentication systems based on cardiac signals, and more specifically on the PPG signal. The latter is widely used in connected watches and medical equipment, and its main purpose is to measure heart rate and oxygen levels in the blood.However, this signal is sufficiently precise and complex to differentiate between individuals and create a new authentication system. The continuous measurement of this signal is already widespread in populations, so it seems logical to seek to use it to create a continuous authentication system.In order to create such a system, we first carried out a state-of-the-art study. This revealed various methodological biases within the community. Identifying these biases prompted us to create a new comparison system and a new method for analyzing the results. We tested and compared over 250 artificial intelligence models capable of recognizing individuals by their heartbeat.We then created a first continuous authentication system based on the PPG signal and studied various corruption attacks. This study enabled us to identify some of the shortcomings of continuous learning.Finally, we determined a new method for optimally parameterizing a continuous authentication system. This procedure maximizes the usability of each user for a given level of security