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). [Acknowledgments - This work was supported by the Ministry of Education and Science of the Republic of Serbia (41006).

Fluktuacije ulova nekih pelagičnih vrsta riba u Mediteranu

U radu su analizirani 63 godine dugački podaci o ulovu tune (Thunnus thynnus) i srdele (Sardina pilchardus) u Mediteranu, metodom spektralne (Fourierove) analize i kros korelacjom. Analiza je pokazala da ulov tune sadrži ciklične komponente od 2.6, 3.65, 5.64, 7.75, 10.34 and 15.5 i verovatno 31 godinu, dok su u ulovu srdele najizraženije bile amplitude od 2.44, 3.65, 6.2, 7.75 i 10.34 godina. Prema tome, oba su vremenska niza bila koherentna u ciklusima od 3.65, 7.75 i 10.34 godina. Takođe je ustanovljeno da je ulov tune koherentan sa indeksom severoatlantske oscilacije (NAO) i to u periodima od 2, 3.35, 4.43, 6.89, 10.34 i verovtno 31 godina. Ovo ukazuje da klimatski ciklusi utiču na fluktuacije populacije ove ribe. Nadalje, upoređenje fluktuacija ulova tune u zapadnom i istočnom Mediteranu je pokazalo da su one potpuno sinhrone

The mechanism of the NH4 ion oscillatory transport across the excitable cell membrane

This paper presents results on typical oscillations of the membrane potential induced by the excitation of the cell membrane by different concentrations of the NH4Cl solution. The existence of four classes of oscillations of the membrane potential and several different single and local impulses rhythmically occurring were determined. It is known that the oscillatory processes of the membrane potential are in direct dependence on oscillatory transport processes of NH4 and Cl ions across the excitable cell membrane. A hypothesis on a possible mechanism of oscillatory transport processes of NH4 and Cl ions across the excitable cell membrane is also presented

Privredni ribolov na Dunavu u Srbiji

U radu se daje pregled slatkovodnog ribarstva sa aspekta upravljanja, ekspolatacije ribljih resursa, tržišta ribom, legislative koja uređuje delatnost ribarstva, kao i problemi sektora ribarstva u Srbiji. Istraživanje i analiza privrednog ribolova na Dunavu kroz Srbiju (588 km toka) sprovedeno je prikupljanjem podataka ribarske statistike za period od 1948. do 2010. godine, njihovim unošenjem u elektronsku bazu i analiziranjem uz korišćenje različitih metoda. Statistički podaci uključuju ukupan ulov, ulov rekreativnog i privrednog ribolova, ulov privredno značajnih vrsta i alohtonih vrsta. Korišćenjem anketnog upitnika za ribare dobijeni su podaci o demografskoj strukturi ribara koji se bave ribarenjem kao osnovnom delatnošću, o sastavu ulova, koliko je ribarstvo perspektivna privredna grana i koji su problemi i potencijalna rešenja. Većina ribara pripada starosnoj grupi koja je u opsegu od 45 do 50 godina. Privredni ribolov je važna ekonomska delatnost i predstavlja osnovni izvor prihoda za većinu ribara. Tržište slatkovodnom ribom je neuređena oblast koja zavisi od ličnog zalaganja i odgovornosti pojedinca koji ima interes u prodaji ribe. Ribarstvo na Dunavu u Srbiji je već dugi niz godina u procesu tranzicije ka tržišnoj ekonomiji. Dugoročne fluktuacije hidroloških podataka (vodostaj) upoređivane su sa fluktuacijama godišnjeg ulova ribe iz Dunava kako bi se uočila eventualna međusobna zavisnost i uporedili njihovi trendovi. Rezultati ovog istraživanja treba da posluže kao pregled stanja sektora sa svim postojećim nedostacima koje treba ispraviti u cilju što uspešnijeg upravljanja ribarstvom na Dunavu i ostalim rekama u Srbiji gde je zastupljen privredni ribolov

Single yeast cell nanomotions correlate with cellular activity.

Living single yeast cells show a specific cellular motion at the nanometer scale with a magnitude that is proportional to the cellular activity of the cell. We characterized this cellular nanomotion pattern of nonattached single yeast cells using classical optical microscopy. The distribution of the cellular displacements over a short time period is distinct from random motion. The range and shape of such nanomotion displacement distributions change substantially according to the metabolic state of the cell. The analysis of the nanomotion frequency pattern demonstrated that single living yeast cells oscillate at relatively low frequencies of around 2 hertz. The simplicity of the technique should open the way to numerous applications among which antifungal susceptibility tests seem the most straightforward

Sleep spindles as an early biomarker of REM sleep disorder in a rat model of Parkinson’s disease cholinopathy

Rhythmic oscillations of neuronal populations, generated by different mechanisms, are present at several levels of the central nervous system and serve many important physiological or reflect pathological functions. Understanding the role of brain oscillations as possible biomarkers of brain function and plasticity is still a challenge, and despite extensive research, their role is still not well established. We recently demonstrated that the hallmarks of earlier aging onset during impaired thalamo-cortical cholinergic innervation (in a rat model of Parkinson’s disease cholinopathy) were consistently expressed, from 3 and one half to 5 and one half months of age, through increased electroencephalographic (EEG) sigma activity amplitude during rapid eye movement (REM) sleep, as a unique aging induced REM sleep phenomenon. In addition, there was altered motor cortical drive during non-rapid-eye-movement (NREM) and REM sleep. In order to explain this new aging-induced REM sleep phenomenon, we analyzed possible differences between control REM sleep spindle activity and REM sleep spindle activity at the onset of REM sleep “enriched“ with sigma activity (at 4 and one half months of age), following bilateral pedunculopontine tegmental nucleus (PPT) cholinergic neuronal loss in the rat. We analzyed differences in spindle density, duration, and frequency. We demonstrated in young adult Wistar rats with the severely impaired PPT cholinergic innervation the alterations in sleep spindle dynamics and pattern during REM sleep in the motor cortex as the earliest biomarkers for the onset of their altered aging processes

Characterization of Coupled Ground State and Excited State Equilibria by Fluorescence Spectral Deconvolution

Fluorescence probes with multiparametric response based on the relative variation in the intensities of several emission bands are of great general utility. An accurate interpretation of the system requires the determination of the number, positions and intensities of the spectral components. We have developed a new algorithm for spectral deconvolution that is applicable to fluorescence probes exhibiting a two-state ground-state equilibrium and a two-state excited-state reaction. Three distinct fluorescence emission bands are resolved, with a distribution of intensities that is excitation-wavelength-dependent. The deconvolution of the spectrum into individual components is based on their representation as asymmetric Siano-Metzler log-normal functions. The application of the algorithm to the solvation response of a 3-hydroxychromone (3HC) derivative that exhibits an H-bonding-dependent excited-state intramolecular proton transfer (ESIPT) reaction allowed the separation of the spectral signatures characteristic of polarity and hydrogen bonding. This example demonstrates the ability of the method to characterize two potentially uncorrelated parameters characterizing dye environment and interactions

Definition of a temporal distribution index for high temporal resolution precipitation data over Peninsular Spain and the Balearic Islands: the fractal dimension; and its synoptic implications

Precipitation on the Spanish mainland and in the Balearic archipelago exhibits a high degree of spatial and temporal variability, regardless of the temporal resolution of the data considered. The fractal dimension indicates the property of self-similarity, and in the case of this study, wherein it is applied to the temporal behaviour of rainfall at a fine (10-min) resolution from a total of 48 observatories, it provides insights into its more or less convective nature. The methodology of Jenkinson & Collison which automatically classifies synoptic situations at the surface, as well as an adaptation of this methodology at 500 hPa, was applied in order to gain insights into the synoptic implications of extreme values of the fractal dimension. The highest fractal dimension values in the study area were observed in places with precipitation that has a more random behaviour over time with generally high totals. Four different regions in which the atmospheric mechanisms giving rise to precipitation at the surface differ from the corresponding above-ground mechanisms have been identified in the study area based on the fractal dimension. In the north of the Iberian Peninsula, high fractal dimension values are linked to a lower frequency of anticyclonic situations, whereas the opposite occurs in the central region. In the Mediterranean, higher fractal dimension values are associated with a higher frequency of the anticyclonic type and a lower frequency of the advective type from the east. In the south, lower fractal dimension values indicate higher frequency with respect to the anticyclonic type from the east and lower frequency with respect to the cyclonic type

Modeling EEG fractal dimension changes in wake and drowsy states in humans: a preliminary study

Aim of this preliminary study was to examine and compare topographic distribution of Higuchi's fractal dimension (FD, measure of signal complexity) of EEG signals between states of relaxed wakefulness and drowsiness, as well as their FD differences. The experiments were performed on 10 healthy individuals using a fourteen-channel montage. An explanation is offered on the causes of the detected FD changes. FD values of 60 s records belonging to wake (Hori's stage 1) and drowsy (Hori's stages 2–4) states were calculated for each channel and each subject. In 136 out of 140 epochs an increase in FD was obtained. Relationship between signal FD and its relative alpha amplitude was mathematically modeled and we quantitatively demonstrated that the increase in FD was predominantly due to a reduction in alpha activity. The model was generalized to include other EEG oscillations. By averaging FD values for each channel across 10 subjects, four clusters (O2O1; T6P4T5P3; C3F3F4C4F8F7; T4T3) for the wake and two clusters (O2O1P3T6P4T5; C3C4F4F3F8T4T3F7) for the drowsy state were statistically verified. Topographic distribution of FD values in wakefulness showed a lateral symmetry and a partial fronto-occipital gradient. In drowsiness, a reduction in the number of clusters was detected, due to regrouping of channels T3, T4, O1 and O2. Topographic distribution of absolute FD differences revealed largest values at F7, O1 and F3. Reorganization of channel clusters showed that regionalized brain activity, specific for wakefulness, became more global by entering into drowsiness. Since the global increase in FD during wake-to-drowsy transition correlated with the decrease of alpha power, we inferred that increase of EEG complexity may not necessarily be an index of brain activation