Amplitude Correlation Research Articles

Spontaneous Variation in Electrocorticographic Resting-State Connectivity.

Prior studies using functional magnetic resonance imaging, electroencephalography, and magnetoencephalography have observed both structured patterns in resting-state functional connectivity and spontaneous longitudinal variation in connectivity patterns independent of a task. In this first study using electrocorticography (ECoG), we characterized spontaneous, intersession variation in resting-state functional connectivity not linked to a task. We evaluated pairwise connectivity between electrodes using three measures (phase locking value [PLV], amplitude correlation, and coherence) for six canonical frequency bands, capturing different characteristics of time-evolving signals. We grouped electrodes into 10 functional regions and used intraclass correlation (ICC) to estimate pairwise longitudinal stability. We found that stronger PLV (PLV ≥0.4) in theta through gamma bands and strong correlation in all bands (R2's ≥0.6) are linked to substantial stability (ICC ≥0.6), but that stability does not imply strong phase locking or amplitude correlation. There was no notable link between strong coherence and high ICC. All within-region PLVs are markedly stable across frequencies. In addition, we highlight interaction patterns across several regions: parahippocampal/entorhinal cortex is characterized by stable, weak functional connectivity except self-connections. Dorsolateral prefrontal cortex connectivity is weak and unstable, except self-connections. Inferior parietal lobule has little stability despite narrow connectivity bounds. We confirm prior studies linking functional connectivity strength and intersession variability, extending into higher frequencies than other modalities, with greater spatial specificity than scalp electrophysiology. We suggest further studies quantitatively compare ECoG to other modalities and/or use these findings as a baseline to capture functional connectivity and dynamics linked to perturbations with a task or disease state.

Intensity Estimation of Electromagnetic Emission from Individual ICs Based on Noise Source Amplitude Modulation and Correlation Analysis

Intensity Estimation of Electromagnetic Emission from Individual ICs Based on Noise Source Amplitude Modulation and Correlation Analysis

The structure of equidistant-frequency groups in the oscillation spectra of the dayside magnetosphere

Abstract The structure of natural signals (geomagnetic field disturbances in the ULF range registered at Mondy and Borok observatories) is studied for the first time by means of the APCF (amplitude and phase correlation function) method, unrelated to spectral analysis but based on analysing a specially constructed correlation function of the amplitude and phase fluctuations in the recorded signal. This method can detect the presence of a group of equidistant frequencies in the spectrum of the original signal as well as measuring the difference, Δ f , of two adjacent frequencies in the group. The end product of the APCF method is a histogram of multiple Δ f values. In the traditional spectral method of signal analysis, the presence in the spectrum of a peak at a certain frequency means that, in the original signal, the oscillation amplitude has a local maximum at this frequency. In the APCF “spectrum” (histogram), each peak corresponds, not to one, but to a whole group of equidistant frequencies in the original signal. The position of the peak on the horizontal axis defines, not a specific frequency, but the difference of two adjacent frequencies which is typical of the entire group. Comparison of one of the histograms for ULF disturbance records with the traditional spectrum shows that the chaotic spectrum, which is generally assumed to be noise, in reality possesses a strictly ordered structure. Most spectral peaks have been found to belong to one of many (more than 10) equidistant frequency groups. In the full spectrum, the peaks of these groups overlap forming a complex chaotic sequence. The analysis of the peaks in all the hist ograms makes it possible to conclude that the equidistant frequency groups corresponding to peaks in each histogram, are eigenfrequencies of a 2D Alfven resonator. The existence of such a resonator in the magnetosphere, in the vicinity of the plasmapause outer edge, was earlier predicted in theoretical studies [Guglielmi, Polyakov, 1983; Leonovich, Mazur, 1987]. The APCF processing method allows this prediction to be confirmed experimentally.

Ultrasonographic and electrophysiologic evaluation of median and ulnar nerves in chronic stroke patients with upper extremity spasticity

Objective: To evaluate the upper extremity nerves of stroke patients morphologically and electrophysiologically and to determine whether there is a relationship between clinical evaluations, ultrasonographic measurements, and electrodiagnostic findings.Methods: This cross-sectional study included 30 chronic stroke patients. After recording demographical data, clinical, ultrasonographic, and electrophysiological evaluations were performed. Clinical evaluations included Brunnstrom Recovery Stages (BRS), Fugl-Meyer Assessment (FMA), Modified Ashworth Scale (MAS), Motricity index (MI), Functional Independence Measurement (FIM), and Functional Ambulation Scale (FAS). For ultrasonographic measurements, median and ulnar nerves were scanned. Median and ulnar nerve conduction studies were performed bilaterally.Results: Mean ages of the patients were 62.2 ± 13.0 years (range 24–84 years; 22 males, 8 females). There was no significant difference in median/ulnar nerve ultrasonographic measurements between paretic and non-paretic sides (p > .05), whereas median nerve motor conduction velocity was significantly slower and median nerve F-wave latency was prolonged on the paretic side (p < .05). The median and ulnar nerve compound motor action potential (CMAP) amplitudes of paretic sides were positively correlated with lower extremity BRS and FAS scores. Median CMAP amplitudes were also positively correlated with FIM scores and ulnar CMAP amplitudes were positively correlated with motricity scores. Moreover, on the paretic side, there were positive correlations of median SNAP amplitudes with FIM and FAS scores (p < .05).Conclusions: Our results showed electrophysiological changes in peripheral nerves on the paretic upper extremities, however, no morphological change was determined. Further studies with larger number of patients and longer follow-up periods are needed to clarify the effect of stroke and spasticity on the peripheral nervous system.

Assessment of ablation catheter contact on valve annulus: Implications on accessory pathway ablation

BackgroundCatheter-tissue contact force is an important factor influencing lesion size and efficacy and thereby potential for arrhythmia recurrence following accessory pathway (AP) radiofrequency ablation. We aim to evaluate adequacy and perception of catheter contact on the tricuspid and mitral annuli.MethodsData were collected from 42 patients undergoing catheter ablation. Operators were blinded to contact force information and reported perceived contact (poor, moderate, or good) while positioning the catheter at four tricuspid annular sites (12, 9, 6 and 4 o'clock positions; abbreviated as TA12, TA9, TA6 and TA4) and three mitral annular sites (3, 5 and 7 o'clock positions; abbreviated as MA3, MA5 and MA7) through long vascular sheaths.ResultsThe highest and lowest mean contact forces were obtained at MA7 (13.3 ± 1.7 g) and TA12 (3.6 g ± 1.3 g) respectively. Mean contact force on tricuspid annulus (6.1 g ± 0.9 g) was lower than mitral annulus (9.8 ± 0.9 g) locations (p = 0.0036), with greater proportion of sites with <10 g contact force (81.7% vs 60.4%; p = 0.0075). Perceived contact had no impact on measured mean contact force for both mitral and tricuspid annular positions (p = 0.959 and 0.671 respectively). There was correlation of both impedance and atrial electrogram amplitude with contact force, though insufficient to be clinically applicable.ConclusionA high proportion of annular catheter applications have low contact force despite being performed with long vascular sheaths in the hands of experienced operators. In addition, there was no impact of operator perceived contact force on actual measured contact force. This may carry implications for success of AP ablation.

EEG can predict speech intelligibility

Objective. Speech signals have a remarkable ability to entrain brain activity to the rapid fluctuations of speech sounds. For instance, one can readily measure a correlation of the sound amplitude with the evoked responses of the electroencephalogram (EEG), and the strength of this correlation is indicative of whether the listener is attending to the speech. In this study we asked whether this stimulus-response correlation is also predictive of speech intelligibility. Approach. We hypothesized that when a listener fails to understand the speech in adverse hearing conditions, attention wanes and stimulus-response correlation also drops. To test this, we measure a listener’s ability to detect words in noisy speech while recording their brain activity using EEG. We alter intelligibility without changing the acoustic stimulus by pairing it with congruent and incongruent visual speech. Main results. For almost all subjects we found that an improvement in speech detection coincided with an increase in correlation between the noisy speech and the EEG measured over a period of 30 min. Significance. We conclude that simultaneous recordings of the perceived sound and the corresponding EEG response may be a practical tool to assess speech intelligibility in the context of hearing aids.

ACCURACY OF BEARING DETERMINATION IN A THREE-CHANNEL MONOPULSE AMPLITUDE CORRELATION DIRECTION FINDER

In the work, the study of the achievable accuracy of determining the coordinates of the radiating in the radio range of spacecraft using a three‑element amplitude correlation direction finder has been performed. The proposed scheme makes it possible to select single and group low‑power complex signals and simultaneously determine the bearings of several sources, the signals of which can be separated in time‑frequency‑code space. As an example, the radiation pattern of a three‑element antenna system with an orthogonal arrangement of partial diagrams with respect to the equal‑signal direction is considered. The results of statistical modeling of the correlation processing algorithm obtained for a three‑channel monopulse system with a 3.7° pattern width and estimates of the potential accuracy of determining the bearing are presented. Simulation results are given to evaluate the instrumental accuracy of the direction finder. The proposed method of direction finding provides the ability to determine the geodetic coordinates of aerospace objects using the station electronic reconnaissance.

Structural and functional connectivity in newly diagnosed juvenile myoclonic epilepsy.

We aimed to evaluate structural and functional connectivity of patients with newly diagnosed juvenile myoclonic epilepsy (JME) compared to healthy subjects. We enrolled 36 patients with a diagnosis of JME, who were newly diagnosed and drug-naïve. They underwent T1-weighted imaging, and structural volumes were calculated using FreeSurfer software. In addition, EEG data were obtained from all of them. Structural and functional connectivity matrices were estimated by calculating the structural volumes and EEG amplitude correlation, respectively. Then, the connectivity measures were calculated using the BRAPH program. We also enrolled healthy subjects to compare its structural and functional connectivity with the patients with JME. We observed that patients with JME exhibited significantly different functional and structural connectivity compared to healthy control subjects. In the global structural connectivity, global efficiency, and local efficiency, and small-worldness index were decreased, whereas characteristic path length was increased in patients with JME. Betweenness centrality of cingulate, precentral, superior parietal, and superior frontal cortex was increased in patients with JME whereas that of hippocampus was decreased. In the functional connectivity, the betweenness centrality of the fronto-central electrodes was significantly increased. This study reports that the structural connectivity and functional connectivity in patients with JME are significantly different from those in healthy control subjects, even those with newly diagnosed drug-naive state. The patients with JME exhibited disrupted topological disorganization of the global brain network and hub reorganization in structural and functional connectivity. These alterations are implicated in the pathogenesis of JME and suggestive of network disease.

Ionic current correlations are ubiquitous across phyla

Ionic currents, whether measured as conductance amplitude or as ion channel transcript numbers, can vary many-fold within a population of identified neurons. In invertebrate neuronal types multiple currents can be seen to vary while at the same time their magnitudes are correlated. These conductance amplitude correlations are thought to reflect a tight homeostasis of cellular excitability that enhances the robustness and stability of neuronal activity over long stretches of time. Although such ionic conductance correlations are well documented in invertebrates, they have not been reported in vertebrates. Here we demonstrate with two examples, identified mouse hippocampal granule cells (GCs) and cholinergic basal forebrain neurons, that the correlation of ionic conductance amplitudes between different ionic currents also exists in vertebrates, and we argue that it is a ubiquitous phenomenon expressed by many species across phyla. We further demonstrate that in dentate gyrus GCs these conductance correlations are likely regulated in a circadian manner. This is reminiscent of the known conductance regulation by neuromodulators in crustaceans. However, in GCs we observe a more nuanced regulation, where for some conductance pairs the correlations are completely eliminated while for others the correlation is quantitatively modified but not obliterated.

Effects of Local and Global Dynamics on the Supertertiary Organization of Postsynaptic Density Protein 95

Postsynaptic density protein 95 (PSD-95) is a critical scaffolding protein in the excitatory postsynaptic density (PSD) with key functions in synaptic organization and regulation of synaptic strength. PSD-95 is a canonical multidomain scaffold protein comprised of three PDZ domains, an SH3 domain, and a guanylate “pseudokinase” (GuK) domain connected in series by flexible polypeptide linkers. The domains of PSD-95 show varying degrees of interaction and were suggested to partition into two independent supramodules. The first two PDZ domains display weak interactions but the third PDZ domain preferentially interacted with the SH3 and GuK domains. Despite a trove of structural studies, we do not understand how the interactions of PSD-95 with its diverse set of synaptic binding partners are regulated. PSD-95 exchanges between supertertiary configurations as part of its functional cycle. Interactions and posttranslational modifications can change the conformation with effects on function. This suggests that internal dynamics may regulate access to binding sites in PSD-95. In this work, we utilize a FRET network designed to probe all pairwise combinations of the five domains. We used multiparameter fluorescence detection and filtered fluorescence correlation spectroscopy to identify interdomain interactions and resolve dynamics from picoseconds to milliseconds. The labeling sites were on α-helices or surface loops. We distinguished locally rigid or flexible sites based on their relative contribution to FRET efficiencies and correlation amplitudes. Global analysis of the entire FRET network allowed comparison of the timescales associated with local and interdomain motions. Describing how local and interdomain dynamics drive the supertertiary organization of PSD-95 provides a basis for understanding how conformational changes regulate multidomain scaffold proteins.

Protein Unfolded States are Characterized by the Duality of Sequence-Specific Conformational Preferences and Ensemble-Averaged Features of Canonical Random Coils

A consensus regarding rigorous, quantitative descriptions of unfolded states of autonomously foldable proteins under folding conditions has remained elusive despite its fundamental importance for a variety of processes in vivo. Here, we combine time-resolved Förster Resonance Energy Transfer (FRET) using multiple non-perturbing, amino-acid-sized dye pairs, paramagnetic relaxation enhancement (PRE) experiments with multiple labels, equilibrium and time-resolved small angle X-ray scattering (SAXS), extensive all-atom simulations, and polymer theory to construct a rigorous, atomistic descriptions for unfolded states of different proteins under their respective folding conditions. Our descriptions summarize sequence-specific contact distributions while provide a framework for quantifying the amplitudes of conformational fluctuations and correlations among these fluctuations. The picture that emerges suggests that unfolded states are conformationally heterogeneous, and this heterogeneity is sequence-specific both in terms of the biases for native as well as non-native contacts. Despite significant conformational heterogeneity, quantifiable biases toward the sequence-specific folded state topologies result from conformational fluctuations in unfolded states. Importantly, we find that converging on a coherent picture for heterogeneous ensembles such as unfolded states under folding conditions requires a combination of readouts from multiple type of experiments that are then integrated with theory and simulation. These methods are also directly applicable to studies of sequence-to-conformation relationships of intrinsically disordered proteins.

Information geometry in a reduced model of self-organised shear flows without the uniform coloured noise approximation

We investigate information geometry in a toy model of self-organised shear flows, where a bimodal PDF of x with two peaks signifying the formation of mean shear gradients is induced by a finite memory time of a stochastic forcing f . We calculate time-dependent probability density functions (PDFs) for different values of the correlation time and amplitude D of the stochastic forcing, and identify the parameter space for unimodal and bimodal stationary PDFs. By comparing results with those obtained under the uniform coloured noise approximation (UCNA) in Jacquet et al (2018 Entropy 20 613), we find that UCNA tends to favor the formation of a bimodal PDF of x for given parameter values and D. We map out attractor structure associated with unimodal and bimodal PDFs of x by measuring the total information length against the location x0 of a narrow initial PDF of x. Here represents the total number of statistically different states that a system passes through in time. We examine the validity of the UCNA from the perspective of information change and show how to fine-tune an initial joint PDF of x and f to achieve a better agreement with UCNA results.

Theoretical analysis of entanglement enhancement with two cascaded optical cavities

Entanglement source with high entanglement degree is the guarantee for accomplishing the quantum information transmission and process with higher fidelity. Continuous variable Einstein-Podolsky-Rosen (EPR) entangled optical field with quantum correlation of amplitude and phase quadrature is a basic and important quantum resource in the quantum information science area, which can be obtained by a non-degenerate optical parametric amplifier (NOPA) operated below the threshold pump power. Because of the limitation of the imperfect performance of optical components in optical cavity, we should find efficient methods of implementing quantum manipulation to improve the entanglement degree of the entangled state of light. Connecting NOPA1 and NOPA2 in series, the entangled state of light output from the NOPA1 can be manipulated by NOPA2, and the entanglement degree can be enhanced under certain conditions. To improve the entanglement degree to a greater extent, the structure of the NOPA1 is chosen as a half-monolithic standing-wave optical resonator with the triple resonance of the pump and two subharmonic modes. The NOPA1 is able to output the entangled optical fields with an entanglement degree of 8.4 dB, which is the highest entanglement generated by a single device so far. The structure of the NOPA2 can be chosen as a standing-wave optical cavity or a four-mirror ring optical cavity. According to the different structures of the NOPA2, we theoretically design two kinds of optical systems with two cascaded cavities and compare the effects of the two optical systems on the continuous variable EPR entanglement cascaded enhancement in detail. Based on the above contrastive analysis, when the entanglement degree of the input optical fields is 8.4 dB and the transmissivity of the output coupler is lower, the structure of a four-mirror ring optical cavity for NOPA2 cannot enhance the entanglement degree, so the optical system including NOPA2 with standing wave cavity structure and the optical isolator with high transmission efficiency is appropriate. When the transmissivity of the output coupler and transmission efficiency of the optical isolator are higher, the structure of the NOPA2 should be chosen as a standing-wave optical cavity, otherwise the structure of the NOPA2 should be chosen as a four-mirror ring optical cavity. We also theoretically analyze the dependence of the correlation degree of output optical fields on physical parameters. The results show that under the conditions of higher input and output coupling efficiency, higher transmission efficiency and lower intro-cavity loss, the entangled state of light with higher entanglement degree can be obtained experimentally. This provides the reference for obtaining entangled optical fields with higher entanglement degree in the future.

Experimental study of neutron counting in a zero-power reactor driven by a neutron source inherent in highly enriched uranium fuels

ABSTRACT Even a zero-power reactor core containing highly enriched uranium has a weak neutron source inherent in uranium 235, and consequently, a neutron counter placed closely to the core without external neutron source registers a certain counting rate. The study of the counting is very important for zero-power reactor physics experiments with a high precision. In this experimental study, first, at a shutdown state of the UTR-Kinki reactor without start-up neutron source, a pulse height distribution of output signals from a neutron proportional counter was measured to confirm that these signals resulted from neutron detections. At several subcritical states of the UTR, then, the Feynman-α analysis was carried out to confirm that the neutrons detected by the counter must be fission neutrons multiplied by fission chain reactions. The correlation amplitude measured in the Feynman-α analysis was much higher than that measured in a previous drive by start-up source. Further, it was also confirmed that the subcriticality dependence of neutron counting rate followed the source multiplication formula. This feature indicated that the one-point model was very successful in the subcritical range including the shutdown state.

Crossover from anomalous to normal diffusion: truncated power-law noise correlations and applications to dynamics in lipid bilayers

The emerging diffusive dynamics in many complex systems show a characteristic crossover behaviour from anomalous to normal diffusion which is otherwise fitted by two independent power-laws. A prominent example for a subdiffusive–diffusive crossover are viscoelastic systems such as lipid bilayer membranes, while superdiffusive–diffusive crossovers occur in systems of actively moving biological cells. We here consider the general dynamics of a stochastic particle driven by so-called tempered fractional Gaussian noise, that is noise with Gaussian amplitude and power-law correlations, which are cut off at some mesoscopic time scale. Concretely we consider such noise with built-in exponential or power-law tempering, driving an overdamped Langevin equation (fractional Brownian motion) and fractional Langevin equation motion. We derive explicit expressions for the mean squared displacement and correlation functions, including different shapes of the crossover behaviour depending on the concrete tempering, and discuss the physical meaning of the tempering. In the case of power-law tempering we also find a crossover behaviour from faster to slower superdiffusion and slower to faster subdiffusion. As a direct application of our model we demonstrate that the obtained dynamics quantitatively describes the subdiffusion–diffusion and subdiffusion–subdiffusion crossover in lipid bilayer systems. We also show that a model of tempered fractional Brownian motion recently proposed by Sabzikar and Meerschaert leads to physically very different behaviour with a seemingly paradoxical ballistic long time scaling.

Long-range strain correlations in 3D quiescent glass forming liquids

Recent two-dimensional computer simulations and experiments indicate that even supercooled liquids exhibit long-lived, long-range strain correlations expected only in solids. Here we investigate this issue in three dimensions via Newtonian molecular-dynamics simulations, by a generalized hydrodynamics approach, and by experiments on Brownian hard-sphere colloids. Both in the glassy state and in liquid regimes, strain correlations are predicted to decay with a power law, reminiscent of elastic fields around an inclusion. In contrast, the temporal evolution of the correlation amplitude is distinct in the liquid state, where it grows linearly with time, and in the glass, where it reaches a time-independent plateau. These predictions are assessed via molecular-dynamics simulations and experiments. In simple liquids, the size of the cooperative strain patterns is of the order of the distance traveled by (high-frequency) transverse sound prior to structural relaxation. This length is of the order of nanometers in a normal liquid and grows to macroscale upon approaching the glass transition.

Mechanism Analysis of PCC Harmonic Resonance Based on Nonlinear Self-Oscillation Concept in a High-Power Grid-Tied Photovoltaic Plant

With the high penetration of photovoltaic systems, the interaction between grid-tied inverters and line impedances results in harmonic resonance at point of common coupling (PCC) in high-power photovoltaic (PV) plants. Thus far, most publications have reported about this issue from a theoretical perspective, and there is no field verification in a real PV plant. To fill this gap, field waveforms are captured in a high-power PV plant to figure out the mechanism of the harmonic resonance phenomenon. This paper, for the first time, presents a nonlinear self-oscillation concept to clarify the mechanism of the harmonic resonance in a high-power PV plant. The field harmonic measurement of a grid-tied PV plant is carried out. The analysis of harmonic spectra and current distributions in a photovoltaic plant shows that these harmonic characteristics are different from the signals generated by the resonances of PV inverter output filters. The correlation of frequency, phase sequence and amplitude show that the different harmonics at PCC are generated by the same source inside PV inverters. Based on the comparison of PCC harmonics with periodic steady-state outputs of nonlinear systems, the nonlinear self-oscillation concept is proposed to clarify the mechanism of the harmonic resonance in a high-power PV plant. The tests in field and signal analysis verify the effectiveness of the proposed method and solution.

Phase shift invariant imaging of coherent sources (PSIICOS) from MEG data

Increasing evidence suggests that neuronal communication is a defining property of functionally specialized brain networks and that it is implemented through synchronization between population activities of distinct brain areas. The detection of long-range coupling in electroencephalography (EEG) and magnetoencephalography (MEG) data using conventional metrics (such as coherence or phase-locking value) is by definition contaminated by spatial leakage. Methods such as imaginary coherence, phase-lag index or orthogonalized amplitude correlations tackle spatial leakage by ignoring zero-phase interactions. Although useful, these metrics will by construction lead to false negatives in cases where true zero-phase coupling exists in the data and will underestimate interactions with phase lags in the vicinity of zero. Yet, empirically observed neuronal synchrony in invasive recordings indicates that it is not uncommon to find zero or close-to-zero phase lag between the activity profiles of coupled neuronal assemblies. Here, we introduce a novel method that allows us to mitigate the undesired spatial leakage effects and detect zero and near zero phase interactions. To this end, we propose a projection operation that operates on sensor-space cross-spectrum and suppresses the spatial leakage contribution but retains the true zero-phase interaction component. We then solve the network estimation task as a source estimation problem defined in the product space of interacting source topographies. We show how this framework provides reliable interaction detection for all phase-lag values and we thus refer to the method as Phase Shift Invariant Imaging of Coherent Sources (PSIICOS). Realistic simulations demonstrate that PSIICOS has better detector characteristics than existing interaction metrics. Finally, we illustrate the performance of PSIICOS by applying it to real MEG dataset recorded during a standard mental rotation task. Taken together, using analytical derivations, data simulations and real brain data, this study presents a novel source-space MEG/EEG connectivity method that overcomes previous limitations and for the first time allows for the estimation of true zero-phase coupling via non-invasive electrophysiological recordings.

Time-Dependent Probability Density Functions and Attractor Structure in Self-Organised Shear Flows.

We report the time-evolution of Probability Density Functions (PDFs) in a toy model of self-organised shear flows, where the formation of shear flows is induced by a finite memory time of a stochastic forcing, manifested by the emergence of a bimodal PDF with the two peaks representing non-zero mean values of a shear flow. Using theoretical analyses of limiting cases, as well as numerical solutions of the full Fokker–Planck equation, we present a thorough parameter study of PDFs for different values of the correlation time and amplitude of stochastic forcing. From time-dependent PDFs, we calculate the information length (), which is the total number of statistically different states that a system passes through in time and utilise it to understand the information geometry associated with the formation of bimodal or unimodal PDFs. We identify the difference between the relaxation and build-up of the shear gradient in view of information change and discuss the total information length () which maps out the underlying attractor structures, highlighting a unique property of which depends on the trajectory/history of a PDF’s evolution.

Correlation of the LeTID amplitude to the Aluminium bulk concentration and Oxygen precipitation in PERC solar cells

Abstract We performed an extensive study of light induced degradation experiments in PERC solar cells made of Boron doped Cz Silicon material from several experimental crystals. Strong LeTID (Light and Elevated Temperature Induced Degradation) amplitudes were found in cells originating from the top and tail part of the crystals. A statistical analysis reveals a strong correlation to the bulk concentration of Aluminium in cells originating from wafers close to the tail. Close to the top, the LeTID effect is strongly enhanced whenever Oxygen precipitation occurs in the cell process.