Electrical characteristics of female and male human skin

Bioimpedance spectroscopy (BIS) is a popular method for characterizing the electrical properties of biological tissues. In this study, BIS measurement data of female and male human skin were analyzed and compared. The electrical characteristics of tissue were followed according to four-parameters of the Cole-Cole model: low frequency resistance R0; high frequency resistance R∞; relaxation time t and parameter a. Individual electrical characteristics of human skin were determined for 30 women and 30 men. The distribution and one-way analysis of variance (one-way ANOVA) of the Cole-Cole parameters R0, R∞, t, a within the human population indicated their different dependence on gender. Parameter a, which is higher in the female subjects (a =0.83±0.03) than in the male subjects (a=0.7±0.05), is strongly dependent on gender (p=0). Parameter R∞ also significantly depends on gender (p=0.002), while t and R0 seem to be slightly related to gender (p>0.05)

Međuzavisnost oscilacija i tranzijenata indukcionih procesa zakasnele fluorescencije hlorofila u tilakoidnoj membrani intaktnog lista kukuruza - reakcije na delovanje viših temperatura i suše

Standard induction processes of delayed fluorescence (DF) of chlorophyll (induction signals) occur when an intact leaf segment of maize inbreds and hybrids is kept in the phosphoroscope darkroom for more than 15 minutes (t > 15 min), and at the same time the leaf is illuminated with the intermittent white light. Resolved induction processes of DF chlorophyll into transients: A, B, C, D and E occur when the intact leaf segment of maize inbreds and hybrids is kept in the phosphoroscope darkroom for a significantly shorter period (500 s > t > 30 s), with the time rate t of 30 s, prior to its illumination with the intermittent white light. Induction transients: A, B, C, D and E are characterized with the time of their generation: tA = 31±6 ms (A), tB = 5 ± 0,5 s (B), tC = 15±5 s (C), tD = 360±20 s (D) and tE = 670±35 s (E), dynamics of changes in transients intensities (IA, IB, IC, ID and IE) and mechanisms of their generation. The induction processes of chlorophyll DF of the intact leaf of maize inbreds and hybrids resolved into transients: A, B, C, D and E are accompanied by the occurrence and different levels of activation energy (Ea, kJ mol-1) that correspond to critical temperatures ranging from 28 to 33°C. The generation mechanisms of induction transients A, B, C, D and E classify them into two groups. Transients A and B are of a physical character, while the transients: C, D, and E are of a chemical character. It is shown that the generation of the induction transients: B, C, D and E simultaneously follows establishing of the oscillations of induction processes of the DF chlorophyll. Oscillating of induction processes of DF chlorophyll is explained by the ion (K+, Na+, H+, Cl-) transport mechanism across the thylakoid membrane of the intact leaf of maize inbreds and hybrids grown under conditions of air drought, increased temperatures and water deficiency in the medium.U ovom radu ostvaruje se primena poboljšanog fotosintetično-fluorescentnog metoda u proučavanju složenih indukcionih procesa zakasnele fluorescencije (ZF) hlorofila, koji su razloženi na tranzijente: A, B, C, D i E i kod kojih mogu da nastanu oscilacije. Međuzavisnost oscilacija i indukcionih tranzijenata: A, B, C, D i E javlja se kod intaktnih listova linija (ZPR 70ž i Oh 43) i hibrida (ZPDC 360, ZPSC 46A, ZPSC 704 i ZPSC 71) kukuruza koji su gajeni u staklari u uslovima različite vazdušne suše, delovanja viših temperatura i deficita vode u podlozi. Posebno se ukazuje na uslove pri kojima dolazi do uspostavljanja standardnih indukcionih procesa ZF hlorofila. Daje se kraći opis standardne indukcione krive ZF hlorofila. Znatno detaljnije daju se eksperimentalni rezultati o razlaganju indukcionih procesa ZF hlorofila na tranzijente: A, B, C, D i E. Pokazani su vremenski i fizičko-hemijski parametri za proučavane indukcione tranzijente. Objašnjeni su njihova priroda i mehanizmi nastajanja. Utvrđene su karakteristike i mehanizam nastajanja oscilacija indukcionih procesa ZF hlorofila. Dati su uslovi pri kojima dolazi do pojave pobuđenog stanja, nastajanja fluktuacija i uspostavljanja oscilacija indukcionih procesa ZF hlorofila u tilakoidnoj membrani intaktnog lista linija i hibrida kukuruza. Izneta je hipoteza o mehanizmu nastajanja oscilacija. Objašnjena je međuzavisnost uspostavljanja oscilacija i tranzijenata indukcionih procesa ZF hlorofila

Electrical properties of human skin as aging biomarkers

A non-invasive bioimpedance spectroscopy (BIS) and Cole-Cole impedance model parameters (R-0, R-infinity, tau and alpha) were used to analyze electrical properties of intact and stripped human skin for both gender subjects divided into younger and older age groups. R-0, R-infinity and tau significantly increased while a significantly decreased with age in stripped skin for both genders (p lt 0.031). Using pooled data with respect to age, gender and skin stripping, R-0, R-infinity and t values were shown to increase with age (p lt 0.0034), R-0, tau and alpha were different between genders (p lt 0.024) and R-0, R-infinity and tau decreased with skin stripping (p lt 0.000008). All of four Cole-Cole parameters were age dependent with specific differences observed for genders and intact and stripped skin layers. Therefore, Cole-Cole parameters, obtained by non-invasive BIS measurements, are a new type of age dependent biomarkers

Dynamics of generating transients of delayed fluorescence induction signal and photosynthetic antennas: A possible relationship: Mathematical modeling approach

A mathematical model was developed for resolved temporal transients of experimentally recorded delayed fluorescence (DF) induction signal. During an intermittent light regime, antennas of the photosynthetic apparatus were treated as targets, repeatedly hit by potentially absorbable photons within a series of consecutive light flashes. Formulas were derived for the number of antennas, cumulatively hit by a specific number of photons, as function of the flash serial number (time). Model parameters included: number of absorbable photons in one flash, antenna sizes and numbers. A series of induction curves were analyzed, obtained from a ZeamaysL. leaf segment and differing in the previous dark period (td). Each curve, consisting of the two most prominent DF transients (C and D), was fitted with several model types, differing in the number of absorbed photons. For both transients, the best fitting result was achieved when DF induction was linked to the second absorbed photon. As expected, model parameters related to antenna sizes showed weaker dependence on td than those referring to antenna numbers. With restrictions applied in this model, the two DF induction transients may be related to two classes of photosynthetic antennas. Their different sizes may have a predominant influence on the efficiency of photon absorption, and possibly time-dependent appearance of DF transients

Electrical properties of human skin as aging biomarkers

A non-invasive bioimpedance spectroscopy (BIS) and Cole-Cole impedance model parameters (R-0, R-infinity, tau and alpha) were used to analyze electrical properties of intact and stripped human skin for both gender subjects divided into younger and older age groups. R-0, R-infinity and tau significantly increased while a significantly decreased with age in stripped skin for both genders (p lt 0.031). Using pooled data with respect to age, gender and skin stripping, R-0, R-infinity and t values were shown to increase with age (p lt 0.0034), R-0, tau and alpha were different between genders (p lt 0.024) and R-0, R-infinity and tau decreased with skin stripping (p lt 0.000008). All of four Cole-Cole parameters were age dependent with specific differences observed for genders and intact and stripped skin layers. Therefore, Cole-Cole parameters, obtained by non-invasive BIS measurements, are a new type of age dependent biomarkers

Prediction of fish catch in the Danube River based on long-term variability in environmental parameters and catch statistics

The effects of physical factors on fish catch in the Serbian part of the Danube River were studied for period of six decades. The data on total catch for the Danube River from river kilometre 845 to river kilometre 1433 were collected from Statistical Office of the Republic of Serbia, while water level and water temperature data were collected from 16 water gauge stations along the investigated part of the Danube River for the period 1948–2009. Cross-correlation functions have been used to analyse the functional connection between Danube water level, water temperature and fish catch while ARMA model which combines cyclic (deterministic) and random (stochastic) components of the analysed sequences was used for the forecasts. The cross-correlation function showed negative correlation between water level and temperature as well as between water temperature and catch and positive correlation between water level and catch. The Danube water level and catch were coherent at the periods of 2.06, 4.13, 6.2, 10.33, 20.66 years, while the cross correlation function between these time series did not show phase lag. The results of reconstruction and forecast of water level, temperature, and catch of fish in the Danube River, obtained by summing the cyclic and stochastic components, was used for the forecast till 2029. In 2016, seven years after, the initial forecasts were made, validity of the model was checked by obtaining data for water temperature, water level and fish catch in the Danube River for the period 2010–2015. Model gave the best prediction for water temperature; average standard error was 1.6 times higher for predicted value than for model value while for fish catch and water level they were 1.96 and 4.97, respectively. Methods used in this work could be powerful tool for prediction of fish catch and serve as the basis for better fisheries management.Science of The Total Environment (2017), 609: 664-67

Modeling the relationship between Higuchi's fractal dimension and Fourier spectra of physiological signals

The exact mathematical relationship between FFT spectrum and fractal dimension (FD) of an experimentally recorded signal is not known. In this work, we tried to calculate signal FD directly from its Fourier amplitudes. First, dependence of Higuchi’s FD of mathematical sinusoids on their individual frequencies was modeled with a two-parameter exponential function. Next, FD of a finite sum of sinusoids was found to be a weighted average of their FDs, weighting factors being their Fourier amplitudes raised to a fractal degree. Exponent dependence on frequency was modeled with exponential, power and logarithmic functions. A set of 280 EEG signals and Weierstrass functions were analyzed. Cross-validation was done within EEG signals and between them and Weierstrass functions. Exponential dependence of fractal exponents on frequency was found to be the most accurate. In this work, signal FD was for the first time expressed as a fractal weighted average of FD values of its Fourier components, also allowing researchers to perform direct estimation of signal fractal dimension from its FFT spectrum