Numerical comparison of compound and extracted eye models for high frequency dosimetry

This paper compares the numerical results for the induced electric field, the specific absorption rate (SAR), and the corresponding temperature increase in two detailed models of the human eye. The first model features the human eye placed in the free space, while the second one incorporates the eye model in the realistic head model obtained from the magnetic resonance imaging (MRI) scans. The electromagnetic model is based on the hybrid FEM/BEM formulation for the biological tissue, whereas the thermal dosimetry model is based on the bioheat equation solved by using the finite element method. The preliminary analysis showed a similar distribution of the induced electric field along the pupillary axis obtained in both models, however, the numerical results for the SAR and related temperature increase showed discrepancy between the two models, which can be attributed to the high values of induced field in the corneal and scleral regions obtained in the compound eye model

On the Applicability of Numerical Quadrature for Double Surface Integrals at 5G Frequencies

The human exposure assessment to wireless communications systems including the fifth generation (5G) mobile systems is related to determining the specific absorption rate (SAR) or the absorbed power density (APD). The assessment of both quantities requires the use of various numerical techniques, including moments method (MoM). As the use of MoM results in a fully populated system matrix, a tremendous computational cost is incurred, both in terms of matrix fill time and memory allocation, as the matrix size is directly related to frequency of the problem. This paper investigates the applicability of numerical integration at frequencies related to 5G. The novelty of this work is related to the comprehensive set of tests of various combination of source and observation triangles using the developed unit cube test. A number of convergence tests were performed to investigate the effects of the increasing frequency and the discretization scheme on the numerical solution, as well as to determine how to curb the computational requirements by the proficient use of numerical integration. The results show that in the lower GHz range, lower integration orders could be used, resulting in the decrease of matrix fill time without loss of solution accuracy

A Study on the Use of Compound and Extracted Models in the High Frequency Electromagnetic Exposure Assessment

The paper presents the numerical results for the induced electric field in the various models of the human eye and the head. The comparison between the extracted or the single organ models and the compound organ models placed inside realistic head models obtained from the magnetic resonance imaging scans is presented. The numerical results for several frequencies and polarizations of the incident electromagnetic (EM) plane wave are obtained using the hybrid finite element method/boundary element method (FEM/BEM) formulation and the surface integral equation (SIE) based formulation featuring the use of method of moments, respectively. Although some previous analysis showed the similar distribution of the induced electric field along the pupillary axis obtained in both eye models, this study showed this not to be the case in general. The analysis showed that the compound eye model is much more suitable when taking into account the polarization of the incident EM wave. The numerical results for the brain models showed much better agreement in the maximum values and distributions of the induced surface field between detailed models, while homogeneous brain model showed better agreement with the compound model in the distribution along selected sagittal axis points. The analysis could provide some helpful insights when carrying out the dosimetric analysis of the human eye and the head/brain exposed to high frequency EM radiation

Five-Year Cumulative Incidence of Unhealthy Diet in Adult Croatian Population: the CroHort Study

This study investigated 5-year cumulative incidence of unhealthy dietary habits across various gender and age groups within the CroHort study, a repeated cross-sectional survey of Croatian adults. The results monitoring the frequency of certain foodstuffs consumption indicate that 10.6% of examinees (10.9% of men, and 9.1% of women) reported worsening of their dietary habits in 2008 as compared to 2003. The cumulative incidence of unhealthy diet was higher in men than in women, and was highest in younger age-groups (18-34 years), both in men and women. The public health programmes should be strengthened in a way which would put a special emphasis on education of younger adults, especially males, on nutrition health impact and healthy diet principles

Origins and genetic legacy of prehistoric dogs

Dogs were the first domestic animal, but little is known about their population history and to what extent it was linked to humans. We sequenced 27 ancient dog genomes and found that all dogs share a common ancestry distinct from present-day wolves, with limited gene flow from wolves since domestication but substantial dog-to-wolf gene flow. By 11,000 years ago, at least five major ancestry lineages had diversified, demonstrating a deep genetic history of dogs during the Paleolithic. Coanalysis with human genomes reveals aspects of dog population history that mirror humans, including Levant-related ancestry in Africa and early agricultural Europe. Other aspects differ, including the impacts of steppe pastoralist expansions in West and East Eurasia and a near-complete turnover of Neolithic European dog ancestry

Five-year cumulative incidence of unhealthy diet in adult Croatian population: the CroHort study [Prehrambene navike: 5-godišnja kumulativna incidencija - CroHort studija]

This study investigated 5-year cumulative incidence of unhealthy dietary habits across various gender and age groups within the CroHort study, a repeated cross-sectional survey of Croatian adults. The results monitoring the frequency of certain foodstuffs consumption indicate that 10.6% of examinees (10.9% of men, and 9.1% of women) reported worsening of their dietary habits in 2008 as compared to 2003. The cumulative incidence of unhealthy diet was higher in men than in women, and was highest in younger age-groups (18-34 years), both in men and women. The public health programmes should be strengthened in a way which would put a special emphasis on education of younger adults, especially males, on nutrition health impact and healthy diet principles

Synthesis of silver nanowires

U suvremenoj tehnologiji i znanosti postoji veliko zanimanje za procese sinteze nanomaterijala. Nanomaterijalima se, između ostalih materijala, smatraju nanožice. Nanožice su omogućile unaprjeđenje pojedinih uređaja u kojima funkcioniraju kao vodljivi sloj u uređajima, odnosno prozirna elektroda. U navedenim primjenama najčešće se koriste srebrne nanožice. Srebrne nanožice izvrstan su vodič električne i toplinske energije što ih čini materijalom idealnim za korištenje prijenosa energije. Postoji više metoda sinteze srebrnih nanožica poput metode tvrdog predloška koja koristi nanoporozne krute (čvrsta tvar sa porama veličine nekoliko nanometara) tvari kako bi se oblikovale nanožice. Postoje još metode mekog predloška od kojih je najvažnija poliol metoda koja koristi organski spoj kao predložak za oblikovanje nanožica. Poliol metoda koristi se češće zbog jednostavnosti i dobrog iskorištenja. U ovom radu proveden je eksperiment sinteze srebrnih nanožica poliol metodom kako bi se iskušala učinkovitost procesa. Eksperiment se sastoji od zagrijavanja etilen glikola na 160 °C u koji se dodaje bakrov(Ⅱ) klorid, otopina poli(vinil-pirolidona) u etilen glikolu i otopina srebrovog nitrata u etilen glikolu. U eksperimentu se nadalje nastojalo izdvojiti srebrne nanožice kako bi se provela njihova analiza i iskušala moguća primjena. Rezultati provedenog eksperimenta pokazali su da su dobivene srebrne nanožice, no sinteza nije bila u potpunosti uspješna zbog malog iskorištenja i djelomičnog nastanka sferičnih čestica.In modern technology and science, there is a great interest for the synthesis processes of nanomaterials. Among other type of nanomaterials are nanowires. Nanowires were step towards improving devices in which they are used as a conductive layer, i.e., transparent electrodes. Silver nanowires are most often used in the mentioned technologies. Silver nanowires are excellent conductors of electrical and thermal energy which makes them the excellent material for use in energy transmission. There are several methods of silver nanowires synthesis, such as the hard template method, which uses nanoporous solids (a solid with pores a few nanometers in size) to form the nanowires. There are also many soft template methods, the most important of which is the polyol method, which uses an organic compound as a template for forming nanowires. The polyol method is used often due to simplicity and good yield. In this work an experiment on the synthesis of silver nanowires using the polyol method was carried out to test the efficiency of the process. The experiment consisted of heating ethylene glycol to 160 °C, adding copper(Ⅱ) chloride, a solution of poly(vinyl-pyrrolidone) in ethylene glycol and a solution of silver nitrate in ethylene glycol. The experiment further aimed to isolation of silver nanowires to carry out their analysis and test possible application. The results of the conducted experiment showed that silver nanowires were obtained, but the synthesis was not completely successful due to poor yield and partial obtaining of spherical particles

A Method for Determining the Envelope of Induced Electric Field on a Simple Human Head Model by Peaks Detection

This paper is on the use of a hybrid boundary element method/finite element method (BEM/FEM) to determine the induced electric field in spherical human head models exposed to high-frequency plane electromagnetic (EM) wave. The geometrically simplified models include the homogeneous one and the non-homogeneous one, featuring compartments such as skin, skull, CSF, and brain. Both models are illuminated by plane EM wave at frequencies including 900 and 1800 MHz, 3500 MHz pertaining to 5G communication systems and also 6000 MHz representing the transition frequency related to the EMF safety standards. The numerical results for the electric field induced in both human head models are presented, while the emphasis is on the electric field along the propagation axis. The novelty of this work is related to the subsequent post-processing of the sampled induced field along the model axis by using two different numerical filtering techniques. It is shown that using the peak detection algorithm, the spline interpolation could be used to estimate the signal envelope. The exponentially decaying nature of the envelope allows to assess the penetration depth of the EM radiation within the biological tissue. Moreover, it is shown that the analytically calculated penetration depth, derived for the unbounded medium, is well reproduced by the numerical computation of EM field