Temporal Trace Research Articles

Mode-Locking Dynamics in an All-PM Figure-Nine Tm-Doped Fiber Laser

We report a study on pulse dynamics in figure-nine Tm-doped all-polarization maintaining fiber laser. We analyzed laser operation from self-starting with multi-pulse dynamic to single-pulse operation by decreasing the pump power from the mode-locking threshold. By choosing a reliable setting of waveplates, our laser was generating pulses at the central wavelength of 1985 nm with a half-width of the spectrum, pulse duration, and pulse energy equal 6.4 nm, 650 fs, 177 pJ for the output port and 19.2 nm, 1279 fs, 57 pJ for the reject port in the single-pulse state. In the multi-pulse state, we recorded optical spectra, temporal waveforms, and average power at both exit ports. By analyzing temporal traces and output to reject port ratio power, we can distinguish between eight states of operation which follow an exact pattern. In the case of the single-pulse regime, we performed a further laser characterization, including relative intensity noise.

The materiality of lines: The kinaesthetics of bodily movement uniting dance and prehistoric cave art

We take two seemingly disparate practices as the foci for this work—dance and prehistoric cave art—in order to illuminate commonalities in embodied practices that reveal new theoretical insights. Whereas, dance clearly uses temporal traces of the body to shape space and create meaning, cave drawings have also begun to be explained and interpreted through kinesthetic and embodied metaphorical techniques. A key element that these fields have in common is the role of lines. The study of lines has become its own field of research, largely due to Ingold's foundational work on “linealogy”. Considering the animate nature of lines and the kinesthetic response they have on the body, contemporary artistic practices can find parallels to the nature of ancient rock art if we recognize the similarity these fields share in the formation of and interpretation of meaning through movement and material engagement. Lines are a phenomenon that, when looked at as traces—memories of movement that once took place—become an organizing principle that brings distant fields like rock art and dance together. Thus, this article takes Tilley's suggestion that “a truly phenomenological study of imagery is grounded in the kinaesthetics of bodily movement” and applies it to three different artistic practices. Tilley proposes that an artifact may be ambiguous in its meaning because it relays a variety of information, which is often layered and contradictory. Here we see, in cognitive archeology, the idea that the articulation of ambiguous lines is an attempt to bring like-minded things (in the thoughts of the one drawing or dancing) together. The authors propose that the ambiguity of lines allows for a type of withness between the mind, body, and environment, allowing us to consider the mind as extended. Lastly, the nature of lines as extended mind motivate us to propose the term of “signature” in order to circumvent the dilemma of a static sign in regards to movement.

Centimeter-level spatial resolution Brillouin optical time domain analyzer using mono-pulse self-difference.

To break through the limitation of pulse width on spatial resolution in the Brillouin optical time-domain analysis system (BOTDA), a novel, to the best of our knowledge, scheme based on mono-pulse self-difference (MPSD) is proposed for centimeter-level spatial resolution. It is performed by the self-difference of the temporal trace generated by a single-shot long pulse in the conventional BOTDA. The concept-proof of the proposed approach is demonstrated, and experimental results are presented where distributed temperature sensing with a 5-cm spatial resolution is realized based on a 40-ns pulse along a 2-km sensing fiber.

A rare case of Mönckeberg medial calcific sclerosis simulating giant cell arteritis

Background: Mönckeberg Medial Calcific Sclerosis (MMCS) is a rare condition that can mimic giant cell arteritis (GCA). It may be misinterpreted as giant cell arteritis by the clinician and cause unnecessary treatments. Therefore, it is a disease that should be differentiated from giant cell arteritis with its clinical, radiological, and pathological findings.
 Case Presentation: A 56-year-old female patient was admitted to our clinic with sudden unilateral vision loss on the right, pain in the right temporal artery trace, scalp sensitivity in the section corresponding to that area, difficulty chewing, and temporal artery sensitivity. He had a history of hemodialysis for 13 years due to hypertension, osteoporosis, a history of renal stones, and end-stage renal failure. In routine blood tests, White Blood Cell: 7.86X109/L, Hemoglobulin: 10.9 g/dL, C-reactive protein: 3.03 mg/L, Erythrocyte sedimentation rate: 53 mm/hour came. As a result of temporal artery biopsy performed for GCA, absence of giant cells, absence of epithelioid histiocytes, absence of pathological findings in the internal elastic lamina, diffuse calcification in the tunica media, and sclerosis was diagnosed as MMCS. 
 Conclusions: In the literature, 4 case reports resemble giant cell arteritis and are diagnosed as MMCS. This case report is a rare case report showing that MMCS can completely mimic GCA findings.

Pollution status and risk assessment of trace elements in Portuguese water, soils, sediments, and associated biota: a trend analysis from the 80s to 2021.

Pollution of water bodies and sediments/soils by trace elements remains a global threat and a serious environmental hazard to biodiversity and human's health. Globalization and industrialization resulted in the increase and availability of these substances in the environment posing unpredictable adverse effects to living organisms. To determine pollution status and risk contamination by trace elements, data available in the literature of the last 40 years on trace elements occurrence in three environmental matrices (water bodies, sediments/soils, and biota) from Continental Portugal were collected (about 90 studies). Data were compared to water and sediment quality guidelines to assess potential ecological risks. Most environmentally relevant hazardous elements include Zn, Cu, Cd, Pb, and As. Various studies found trace elements at levels higher than those considered safe by environmental guidelines. In surface waters, Al, Zn, Se, and Ag were found above aquatic life limits in about 60% of the reviewed papers, while Cu, Zn, and As exceed those values in more than 60% of mining waters. Hg and Cd in sediments from mining areas exceeded aquatic life limits and potential ecological risk showed extremely high risk for most of the elements. The data compiled in this review is very heterogenous, varying in terms of sampling schemes, trace elements analysed, and spatiotemporal settings. This heterogenicity leads to data differences that make meaningful comparisons difficult. Nevertheless, the compilation of scattered environmental spatial and temporal trace elements data, of either natural sources or human activity as well as the ultimate effect on biological systems, is of the upmost importance to broaden its knowledge, risk assessment, and implementation of mitigation measures.

Peaceful coexistence of thermal equilibrium and the emergence of time

We consider a quantum universe composed of a small system $S$ and a large environment. It has been demonstrated that, for the vast majority of randomly chosen wave functions of the universe satisfying a total energy constraint, the reduced density matrix of the system $S$ is given by the canonical statistical distribution. Here, through the Page-Wootters mechanism, we show that time and nonequilibrium dynamics can emerge as a consequence of the entanglement between the system and the environment present in the (randomly chosen) global wave function of the universe. The clock is provided by the environment, which ticks the temporal evolution of $S$. The paradox of the peaceful coexistence of statistical equilibrium and nonequilibrium dynamics is solved by identifying the trace over the environment degrees of freedom with the temporal trace over the entire history of the system $S$.

Decontaminate Traces From Fluorescence Calcium Imaging Videos Using Targeted Non-negative Matrix Factorization.

Fluorescence microscopy and genetically encoded calcium indicators help understand brain function by recording large-scale in vivo videos in assorted animal models. Extracting the fluorescent transients that represent active periods of individual neurons is a key step when analyzing imaging videos. Non-specific calcium sources and background adjacent to segmented neurons contaminate the neurons’ temporal traces with false transients. We developed and characterized a novel method, temporal unmixing of calcium traces (TUnCaT), to quickly and accurately unmix the calcium signals of neighboring neurons and background. Our algorithm used background subtraction to remove the false transients caused by background fluctuations, and then applied targeted non-negative matrix factorization to remove the false transients caused by neighboring calcium sources. TUnCaT was more accurate than existing algorithms when processing multiple experimental and simulated datasets. TUnCaT’s speed was faster than or comparable to existing algorithms.

Spectrally filtered ps–ns emission dynamics of atmospheric-pressure nanosecond pulsed plasmas

The temporal dynamics of atmospheric-pressure nanosecond pulsed plasma discharges in a pin-to-pin electrode configuration are studied using streak-camera line imaging of the interelectrode gap with a time resolution as short as ∼25 ps. Discharge emission initiates homogeneously throughout the interelectrode gap with no detectable streamer propagation and then temporally decays in two distinct phases. Plasma emission bands attributed to various electronic transitions are tracked for single discharges in air and N2. Spectral filtering of the excited molecular states reveals that the N2(C–B) and N2(B–A) emission bands evolve in distinct early and late phases, respectively, with a time separation of ∼15–20 ns. Furthermore, significant differences in the temporal dynamics of plasma discharges in air and N2 are observed. High levels of excited-state atomic oxygen and NO appear after the initial decay of the N2(C) state and coincide primarily with the latter phases of plasma evolution in air environments. From temporal traces of discharge emission, the formation and relaxation timescales of the electronically excited states of N2 are quantified in pure N2 and air environments with sub-nanosecond resolution. The streak-OES (optical emission spectroscopy) technique enables quantitative time-resolved studies of key chemical species for model validation in ultra-short-pulsed plasmas.

A global scheduling approach for cycle time control in complex manufacturing systems

This paper proposes a novel global scheduling approach for cycle time control strategy in large complex manufacturing systems with multiple workcentres, such as semiconductor manufacturing systems. The interaction between workcentres is taken into account by using global information such as release quantities, the Work-In-Process (WIP), cycle time targets and machine capacities. Local scheduling decisions in workcentres are steered by production targets, i.e. quantities of products to complete in each operation and each period on a scheduling horizon. These global production targets are determined by a mathematical model (global scheduling model), which optimises the satisfaction of cycle time targets. One of the major innovations of the proposed model is that it relies on the temporal trace of the WIP. The mathematical model is coupled with a generic multi-method simulation model for evaluation purpose. Computational experiments conducted on industrial data show that our global scheduling approach efficiently controls the cycle times of products.

Wireless Wearable Ultrasound Sensor to Characterize Respiratory Behavior.

A wireless wearable sensor on a paper substrate was used to continuously monitor respiratory behavior that can extract and deliver clinically relevant respiratory parameters to a smartphone. Intended to be placed horizontally at the midpoint of the costal margin and the xiphoid process as determined through anatomical analysis and experimental test, the wearable sensor is compact at only 40×35×6mm3 in size and 6.5g weight including a 2.7g lithium battery. The wearable sensor, consisting of an ultrasound emitter, an ultrasound receiver, wireless transmission system, and associated data acquisition, measures the linear change in circumference at the attachment location by recording and analyzing the changes in ultrasound pressure as the distance between the emitter and the receiver changes. Changes in ultrasound pressure corresponding to linear strain are converted to temporal lung volume data and are wirelessly transmitted to an associated custom-designed smartphone app. Processing the received data, the mobile app is able to display the temporal volume trace and the flow rate vs. volume loop graphs, which are standard plots used to analyze respiration. From the plots, the app is able to extract and display clinically relevant respiration parameters, including forced expiratory volume delivered in the first second of expiration (FEV1) and forced vital capacity (FVC). The sensor was evaluated with eight volunteers, showing a mean difference of the FEV1/FVC ratio as bounded by 0.00-4.25% when compared to the industry-standard spirometer results. By enabling continuous tracking of respiratory behavioral parameters, the wireless wearable sensor helps monitor the progression of chronic respiratory illnesses, including providing warnings to asthma patients and caregivers to pursue necessary medical assistance.

Abstract 11415: Extent of Leaflet Coaptation Governs the Biomechanics of Mitral Valve Neochordae Used for Posterior Leaflet Prolapse

Introduction: Reducing peak forces and stresses on the neochordae used to repair mitral valve prolapse, can inhibit their late failure, and increase repair durability. Restoring a larger shelf of leaflet coaptation at the time of repair, could reduce neochordae stresses and aid durability. Hypothesis: In this study, we hypothesized that using a slightly smaller annuloplasty ring can yield a higher systolic coaptation length, which in turn could reduce the neochordal forces/stresses. Methods: Pig MV (n=7) were excised and studied in a pulsatile left heart simulator ( Fig. A ), with P2 prolapse induced by transecting the marginal chordae ( Fig B1,2 ). Repair was performed with force transducer instrumented Goretex PTFE suture loops (6-0) ( Figure C1,2 ), and annuloplasty with a custom adjustable ring that could be reduced from 36mm to 30mm in 2mm increments ( Fig D1,2 ). Regurgitant fraction, leaflet coaptation, and temporal neochordae force traces were measured. Results: P2 prolapse increased MR compared to baseline (10.5 ± 7.7% vs 0%, p=0.0001), which was reduced by neochordoplasty and annuloplasty ( Fig. E ). Leaflet coaptation length increased from 0mm to 11.3 ± 3.8mm with neochordae alone, and further increased with annuloplasty to 12.7 ± 3.6mm with 34mm, 14.8 ± 4.4mm with 32mm and 15.7 ± 3.9mm with 30mm ( Fig. F ). With increasing coaptation, the peak neochordae forces reduced ( Fig G, H ), demonstrating a negative correlation between parameters ( Fig I ). Conclusions: Neochordal forces can be reduced by increasing the coaptation length with slight downsizing of the mitral annulus. An operative strategy achieving larger coaptation can yield a biomechanically optimal repair configuration, potentially improving durability.

High pulse energy, narrow-linewidth all-fiber 1064 nm picosecond master oscillator power amplifier system

We demonstrated the generation of narrow spectral bandwidth, high energy picosecond pulses from a low repetition rate SESAM mode-locked laser seeded Yb-doped fiber MOPA system. A short large mode field diameter gain fiber (DCF-30/250) was adopted to efficiently reduce the influence of nonlinear effects. The maximum pulse energy of 12.36 μJ, ∼60 ps pulses with a narrow bandwidth was obtained at a repetition rate of 5 MHz, corresponding to the peak power of 0.2 MW and average output power of 64 W. The optical-to-optical conversion efficiency was ∼64% in such a low repetition rate all-fiber laser design. The output pulse spectra and temporal trace of the MOPA system for different output powers was investigated by simulation. The simulation results were in agreement with experiment but further showed that the spectral splitting would occur as output power increased.

Weekly Crime Concentration

ObjectivesExamine and visualise the temporal concentration of different crime types and detect if their intensity varies through distinct moments of the week.MethodsThe “heartbeat of the crime signal” is constructed by overlapping the weekly time they were suffered. This study is based on more than 220,000 crimes reported to the Mexico City Police Department between January 2016 and March 2020 to capture the day and time of crimes and detect moments of the week in which the intensity exceeds the average frequency. A new metric for the temporal concentration of crime is constructed for different types of crime and regions of the city based on the corresponding heartbeats.ResultsThe temporal concentration of crime is a stable signature of different types of crime. The intensity of robberies and theft is more homogeneous from Monday to Sunday, but robberies of a bank user are highly concentrated in a week, meaning that few hours of the week capture most of the burning moments. The concentration is not homogeneously distributed in the city, with some regions experiencing a much higher temporal concentration of crime.ConclusionsCrime is highly concentrated when observed in its weekly patterns, but different types of crime and regions exhibit substantially distinct concentration levels. The temporal trace indicates specific moments for the burning times of different types of crime, which is a critical element of a policing strategy.

Darting towards Storm Shelter: A minute dinosaur trackway from southern Africa

Theropod dinosaurs are considered the main terrestrial carnivores in the Jurassic and Cretaceous. Their rise to dominance has been linked to, among others, body size changes in their early history, especially across the Triassic–Jurassic boundary. However, to qualitatively assess such temporal trends, robust skeletal and trace fossil data sets are needed globally. The richly fossiliferous southern African continental rock record in the main Karoo Basin offers an unparalleled perspective for such investigations. Herein, by documenting a newly discovered Early Jurassic trackway of very small, functionally tridactyl tracks near Storm Shelter (Eastern Cape) in South Africa, the track record can be expanded. Based on ichnological measurements at the ichnosite and digital 3D models, the footprint dimensions (length, width, splay), locomotor parameters (step length, stride, speed), and body size estimates of the trackmaker are presented. In comparison to other similar tracks, these footprints are not only the smallest Grallator-like tracks in the Clarens Formation, but also the most elongated dinosaur footprints in southern Africa to date. The tracks also show that the small-bodied bipedal trackmaker dashed across the wet sediment surface at an estimated running speed of ~12.5 km/h. During the dash, either as a predator or as a prey, the trackmaker’s small feet sunk hallux-deep into the sediment. The tracking surface is overgrown by fossilised microbial mats, which likely enhanced the footprint preservation. Based on track morphometrics and the regional dinosaur skeletal record, the trackmakers are attributed to Megapnosaurus rhodesiensis (formerly Syntarsus rhodesiensis), a small-to-medium-sized, early theropod common in southern Africa.Significance:
 
 A newly discovered Early Jurassic theropod trackway in South Africa contains not only the smallest tracks in the Clarens Formation, but also the most elongated dinosaur footprints in southern Africa to date.
 The tracks show that the small bipedal trackmaker dashed across the wet sediment surface at an estimated running speed of ~12.5 km per hour.
 During the run, the trackmaker’s feet sunk so deeply into the sediment that even the forwards-directed halluces were impressed.
 
 Open data set: https://doi.org/10.6084/m9.figshare.13007240.v1

Generalized Eigenvalue Decomposition Applied to Estimation of Spatial rPPG Distribution of Skin

Remote photoplethysmography (rPPG) has been at the forefront recently, thanks to its capacity in estimating non-contact physiological parameters such as heart rate and heart rate variability (Wang et al. in FBB 6:33, 2018). rPPG signals are typically extracted from facial videos by performing spatial averaging to obtain temporal RGB traces. Although this spatial averaging simplifies computation, it is accompanied by loss of essential spatial information which might reveal interesting relationships between signals from different spatial regions. In this article, we present a novel algorithm adapted from generalized eigenvalue decomposition (GEVD) to estimate this spatial rPPG distribution. GEVD is an extremely versatile algorithm that finds uses in signal and image processing and analytical problems such as principal component analysis and Fisher discriminant analysis (Ghojogh et al. in Tutorial 2: 1–8, 2019)(Han and Clemmensen in PR 49:43-54, 2016). It is performed using the QZ algorithm (Moler and Stewart in JNA 10(2):241–256, 2010), which in turn uses Householder transformations (Householder in JACM 5(4):339–342, 1958) to extract generalized eigenvectors of a pair of matrices. We adapt the QZ algorithm for the domain of spatio-temporal biomedical signals such as remote photoplethysmography (rPPG), electrocardiography and electroencephalography signals. We call this algorithm Temporal-QZ, which employs vectorization techniques to extract generalized eigenvectors over spatial data points simultaneously. We validate this extension in the domain of remote photoplethysmography (rPPG) measurement, for the estimation of spatial rPPG distribution of skin.

Darting towards Storm Shelter: a minute dinosaur trackway from southern Africa

Theropod dinosaurs are considered the main terrestrial carnivores in the Jurassic and Cretaceous. Their rise to dominance has been linked to, among others, body size changes in their early history, especially across the Triassic–Jurassic boundary. However, to qualitatively assess such temporal trends, robust skeletal and trace fossil data sets are needed globally. The richly fossiliferous southern African continental rock record in the main Karoo Basin offers an unparalleled perspective for such investigations. Herein, by documenting a newly discovered Early Jurassic trackway of very small, functionally tridactyl tracks near Storm Shelter (Eastern Cape) in South Africa, the track record can be expanded. Based on ichnological measurements at the ichnosite and digital 3D models, the footprint dimensions (length, width, splay), locomotor parameters (step length, stride, speed), and body size estimates of the trackmaker are presented. In comparison to other similar tracks, these footprints are not only the smallest Grallator-like tracks in the Clarens Formation, but also the most elongated dinosaur footprints in southern Africa to date. The tracks also show that the small-bodied bipedal trackmaker dashed across the wet sediment surface at an estimated running speed of ~12.5 km/h. During the dash, either as a predator or as a prey, the trackmaker’s small feet sunk hallux-deep into the sediment. The tracking surface is overgrown by fossilised microbial mats, which likely enhanced the footprint preservation. Based on track morphometrics and the regional dinosaur skeletal record, the trackmakers are attributed to Megapnosaurus rhodesiensis (formerly Syntarsus rhodesiensis), a small-to-medium-sized, early theropod common in southern Africa.Significance: A newly discovered Early Jurassic theropod trackway in South Africa contains not only the smallest tracks in the Clarens Formation, but also the most elongated dinosaur footprints in southern Africa to date. The tracks show that the small bipedal trackmaker dashed across the wet sediment surface at an estimated running speed of ~12.5 km per hour. During the run, the trackmaker’s feet sunk so deeply into the sediment that even the forwards-directed halluces were impressed. Open data set: https://doi.org/10.6084/m9.figshare.13007240.v1

The heartbeat of the city.

Human activity is organised around daily and weekly cycles, which should, in turn, dominate all types of social interactions, such as transactions, communications, gatherings and so on. Yet, despite their strategic importance for policing and security, cyclical weekly patterns in crime and road incidents have been unexplored at the city and neighbourhood level. Here we construct a novel method to capture the weekly trace, or "heartbeat" of events and use geotagged data capturing the time and location of more than 200,000 violent crimes and nearly one million crashes in Mexico City. On aggregate, our findings show that the heartbeats of crime and crashes follow a similar pattern. We observe valleys during the night and peaks in the evening, where the intensity during a peak is 7.5 times the intensity of valleys in terms of crime and 12.3 times in terms of road accidents. Although distinct types of events, crimes and crashes reach their respective intensity peak on Friday night and valley on Tuesday morning, the result of a hyper-synchronised society. Next, heartbeats are computed for city neighbourhood 'tiles', a division of space within the city based on the distance to Metro and other public transport stations. We find that heartbeats are spatially heterogeneous with some diffusion, so that nearby tiles have similar heartbeats. Tiles are then clustered based on the shape of their heartbeat, e.g., tiles within groups suffer peaks and valleys of crime or crashes at similar times during the week. The clusters found are similar to those based on economic activities. This enables us to anticipate temporal traces of crime and crashes based on local amenities.

Intact Female Mice Acquire Trace Eyeblink Conditioning Faster than Male and Ovariectomized Female Mice.

Female subjects have been widely excluded from past neuroscience work because of a number of biases, including the notion that cycling sex hormones increase variability. However, it is necessary to conduct behavioral research in mice that includes both sexes as mice are typically used for developing and evaluating future therapeutics. Understanding sex differences in learning is fundamental for the development of targeted therapies for numerous neurologic and neurodegenerative disorders, including Alzheimer’s disease, which is more prevalent in females than males. This study set out to confirm the role of sex and necessity of circulating ovarian hormones in the acquisition of the temporal associative memory task trace eyeblink conditioning (tEBC) in C57BL/6J mice. We present evidence that sex and ovarian hormones are important factors in learning. Specifically, intact female mice learn significantly faster than both male and ovariectomized (ovx) female mice. Data from pseudoconditioned control mice indicate that sex differences are because of differences in learned associations, not sensitization or spontaneous blink rate. This study strengthens the idea that ovarian hormones such as estrogen and progesterone significantly influence learning and memory and that further research is needed to determine the underlying mechanisms behind their effects. Overall, our findings emphasize the necessity of including both sexes in future behavioral studies.

Drawing the room | Drawing within the room

This project report outlines ongoing collaborative design research that addresses aspects of architectural drawing, in particular scale and time. This project is discussed through the lens of the inhabitation of drawing: in both the making of, and encountering, drawing. ‘Drawing the Room | Drawing within the Room’ (2019) couples projective drawings with post factum documentation – or creative post-occupancy data – of built houses. Using motion capture technology, the movements of inhabitation are captured and translated to line work animations. The resulting drawings of inhabitation are projected full-scale, exhibited in the space of the architectural office, the site of conceiving and production of both drawings and architecture. Using the architectural office as the space of installation and exhibition presents a practice for acknowledging and engaging with these spaces of creativity, beyond casting the office as commercial space. The project explores contemporary performative drawing practices within architecture and considers the ways in which bodies and drawings interact. This work highlights the fundamental importance of lines within architecture, not as demarcation, divider or indexical references, but as temporal traces of bodily movement.

Wavelet Variance Maximization: A contactless respiration rate estimation method based on remote photoplethysmography

Respiration is an important parameter in critical and pediatric care since its monitoring allows medical staff to detect many life-threatening diseases. One of the existing monitoring methods is based on remote photoplethysmography (rPPG). This technique consists of extracting a signal related to blood volume variations using a camera. This signal carries useful physiological information such as cardiac and respiratory rates. However, the quality of the signal is lower than regular contact-based methods and represents a major weakness of the rPPG method. In this paper, we propose an algorithm to explicitly maximize the respiratory signal quality by maximizing the Signal-to-Noise Ratio (SNR). Instead of using the regular Fast-Fourier-based energy ratio for the signal-to-noise-ratio estimation, we propose to use the continuous wavelet transform to deal with non-stationarities of the respiratory signal. The method, named Wavelet Variance Maximization (WVM), is based on the Generalized Eigen Value Decomposition (GEVD) algorithm and estimates the optimal combination of the temporal color traces to obtain a high-quality rPPG signal. Our method was tested on 12 healthy adult volunteers and the results confirm that the estimated signal has better quality than existing methods, with approximately 20% reduction of error compared to the best tested state-of-the-art method.