Volume 69, Number 2, 2017
 
THEORETICAL, MATHEMATICAL, AND COMPUTATIONAL PHYSICS
 
Quantum black holes effects on the shape of extensive air showers
N. ARSENE, L.I. CARAMETE, P.B. DENTON, O. MICU
Rom. Rep. Phys. 69, 105 (2017)
Abstract. We investigate the possibility to find a characteristic TeV scale quantum black holes decay signature in the data recorded by cosmic rays experiments. TeV black holes can be produced via the collisions of ultra-high energetic protons (E > 1018 eV) with nucleons from the from atmosphere. We focus on the case when the BH decays specifically into two particles. These particles are then boosted in the Earth reference frame (back-to-back in the center of mass reference frame) and induce two overlapping showers. When reconstructing both the energy and the shape of the resultant air shower, there is a significant difference between showers induced only via standard model interactions and showers produced via the back-to-back decay of BH's as intermediate states.
Article no. 105: PDF 
 
Abelian Higgs model and its phase transitions revisited
RENATA JORA
Rom. Rep. Phys. 69, 106 (2017)
Abstract. The abelian Higgs model and its phase structure are discussed from the perspective that the gauge and scalar fields admit a dual description in terms of fermion variables. The results which indicate the presence of three main phases: Coulomb, Higgs and confinement agree well with those in the literature although a nonstandard order parameter is employed.
Article no. 106: PDF 
 
Elusive noninteracting localized solutions of (2+1)-dimensional Maccari equation
K. SUBRAMANIAN, C. SENTHIL KUMAR, R. RADHA, T. ALAGESAN
Rom. Rep. Phys. 69, 107 (2017)
Abstract. In this paper, we employ the Truncated Painleve Approach (TPA) to (2+1)-dimensional Maccari equation and construct its solutions in closed form involving three lower dimensional arbitrary functions that are completely separated in the spatial and temporal variables. We then suitably harness the arbitrary functions to generate localized solutions like dromions, rogue waves, stationary rogue waves, lumps, and compactons. The highlight of the results is that the localized solutions do not evolve in space and their amplitude alone changes with time despite possessing an explicit time dependence in their structure. Besides, they are also found to be noninteracting.
Article no. 107: PDF 
 
Two (3+1)-dimensional Gardner-type equations with multiple kink solutions
A.-M. WAZWAZ
Rom. Rep. Phys. 69, 108 (2017)
Abstract. In this work we introduce two (3+1)-dimensional Gardner-type equations. We find the necessary conditions for the multiple kink solutions to exist. We show that each model possesses distinct conditions to guarantee the existence of multiple kink solutions.
Article no. 108: PDF 
 
New heat and Maxwell's equations on Cantor cubes
A.K. GOLMANKHANEH, D. BALEANU
Rom. Rep. Phys. 69, 109 (2017)
Abstract. The fractal physics is an important research domain due to its scaling properties that can be seen everywhere in the nature. In this work, the generalized Maxwell's equations are given using fractal differential equations on the Cantor cubes and the electric field for the fractal charge distribution is derived. Moreover, the fractal heat equation is defined, which can be an adequate mathematical model for describing the flowing of the heat energy in fractal media. The suggested models are solved and the plots of the corresponding solutions are presented. A few illustrative examples are given to demonstrate the application of the obtained results in solving diverse physical problems.
Article no. 109: PDF 
 
On the q-deformed modified Kadomtsev-Petviashvili hierarchy and its additional symmetries
K. TIAN, Y. GE, X. ZHU
Rom. Rep. Phys. 69, 110 (2017)
Abstract. The paper aims to construct the q-deformed modified Kadomtsev-Petviashvili (q-mKP) hierarchy and its additional symmetries. The results give the different properties and relationship between the q-mKP hierarchy and the classical mKP hierarchy.
Article no. 110: PDF 
 
 
PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
 
A feasibility study to track cosmic muons using a detector with SIPM devices based on amplitude discrimination
D. STANCA, M. NICULESCU-OGLINZANU, I. BRANCUS, B. MITRICA, A. BALACEANU, B. CAUTISANU, A. GHERGHEL-LASCU, A. HAUNGS, H.-J. MATHES, H. REBEL, A. SAFTOIU, O. SIMA, T. MOSU, T. ALIONTE, B. ALKOTBE, D. STOIAN
Rom. Rep. Phys. 69, 301 (2017)
Abstract. The possibility to build a SiPM-readout muon detector (SiRO), using plastic scintillators with optical fibers as sensitive volume and readout by SiPM photo-diodes, is investigated. SiRO shall be used for tracking cosmic muons based on amplitude discrimination. The detector concept foresees a stack of 6 active layers, grouped in 3 sandwiches for determining the muon trajectories through 3 planes. After investigating the characteristics of the photodiodes, tests have been performed using two detection modules, each being composed from a plastic scintillator sheet, 100 × 25 × 1 cm3 , with 12 parallel, equidistant ditches; each ditch filled with an optical fiber of 1.5 mm thickness and always two fibers connected to form a channel. The attenuation of the light response along the optical fiber and across the channels have been tested. The measurements of the incident muons based on the input amplitude discrimination indicate that this procedure is not efficient and therefore not sufficient, as only about 30% of the measured events could be used in the reconstruction of the muon trajectories. Based on the studies presented in this paper, the layout used for building the SiRO detector will be changed as well as the analog acquisition technique will be replaced by a digital one.
Article no. 301: PDF 
 
 
OPTICS AND PHOTONICS, PLASMAS, LASER AND BEAM PHYSICS
 
Nonstationary exponential distributions of the statistical breakdown time delay in argon DC glow discharge at low pressure
S.N. STAMENKOVIC, V.LJ. MARKOVIC, A.P. JOVANOVIC, M.N. STANKOV
Rom. Rep. Phys. 69, 408 (2017)
Abstract. The experimental distributions of statistical breakdown time delay ts in argon DC glow discharge, with unconditioned electrodes, at low pre-ionization levels are presented. Because of low level of residual particles exponential distributions are expected. However, the data deviate from expected distributions and for their description the nonstationary exponential distribution with time dependent distribution parameter YP that reflects unstable experimental conditions, is necessary (Y is electron yield, P the breakdown probability). For data analysis, Laue diagrams, cumulative, as well as density distributions are used. The obtained data are also fitted by the stationary exponential and Weibull distributions for the sake of comparison.
Article no. 408: PDF 
 
Monochromatization and polarization of the neon spectral lines in constant/variable magnetic field
I. GRUIA, L.C. CIOBOTARU
Rom. Rep. Phys. 69, 409 (2017)
Abstract. As early as the 1980s, a new physical phenomenon was observed in electronegative-electropositive gas mixtures discharges plasma, namely a significant monochromatization effect (called the M-effect) of the emitted visible light. As was established in our previous papers, the generation mechanism of this effect is mainly based on the polar resonant three-body reaction, whose cross-section strongly depends on the energy dissipated in discharge, either by increasing the total gas pressure or the electric current in discharge. In (Ne+H2) gas mixtures, the phenomenon of monochromatization was the most intensive such that the only important spectral line, virtually remaining, was λ = 585.3 nm that belongs to the neon emission spectrum. This paper deals with the study of way in which a constant/variable magnetic field influences the monochromatization and polarization degree, in regard with the neon principal spectral lines: 614.30, 640.22, 692.94, 703.24, 717.39 and 724.51 nm. Given the dependence of the cross-section of the three-body reaction on the energy reaction, the measurements have been performed for different values of the discharge current. The study reveals that the presence of a constant magnetic field improves the quality of the monochromatization-effect and, subsequently, of the polarization degree for the neon spectral lines, particularly λ = 585.3 nm, compared with the situation when the magnetic field is zero or a variable one.
Article no. 409: PDF 
 
 
CONDENSED AND SOFT MATTER PHYSICS
 
Nicotine adsorption on BN porous sheets: a density functional theory study
R. MAJIDI, A.R. KARAMI
Rom. Rep. Phys. 69, 503 (2017)
Abstract. The usage of BN porous sheet as sensor for detection of nicotine molecule was investigated. The structural and electronic properties of three different BN porous sheets were calculated by density functional theory. The calculations show that nicotine molecule is physisorbed on BN porous sheets and charge is transferred from molecule to sheet. Adsorption of the donor molecule makes these BN porous structures with insulating properties, n-type semiconductors. The sensitivity of the electronic properties of BN porous sheets to the presence of nicotine molecule indicates the possibility of using these sheets as sensor for nicotine detection.
Article no. 503: PDF 
 
Reduction of freestanding graphene oxide films using continuous wave laser
ION CALINA, MARIA DEMETER, EUGENIA BADITA, ELENA STANCU, ANCA SCARISOREANU, CATALIN VANCEA
Rom. Rep. Phys. 69, 504 (2017)
Abstract. This paper describes a novel approach to the preparation of reduced graphene oxide films. Freestanding reduced graphene oxide (rGO) films were obtained by exposing graphene oxide films to a continuous wave laser diode and were investigated by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and X-ray diffraction (XRD) to observe their different structural properties (existence of oxygen-containing functional groups, or defects). Thermal, optical, and electrical properties were also discussed along with the potential applications of reduced graphene oxide (rGO) freestanding films.
Article no. 504: PDF 
 
 
BIOPHYSICS AND MEDICAL PHYSICS
 
Dosimetric evaluation study on conventional and 3D conformal brachytherapy treatment of cervix cancer
M.T. GEORGESCU, A. TANASE, M. DUMITRACHE, B. ILEANU, R. ANGHEL
Rom. Rep. Phys. 69, 608 (2017)
Abstract. The purpose of this study was to compare International Commission on Radiation Units and Measurements (ICRU, report 38) reference points, used in conventional brachytherapy planning, with Computed Tomography (CT)-based volumetric calculations of radiation doses for target volumes and organs at risk in biopsy-proven cervix carcinoma patients. All patients underwent brachytherapy using CT-compatible applicators, followed by both conventional and CT scanning. The results confirm that point A radiation dose prescription overestimates target volume coverage, meanwhile for organs at risk the dose is underestimated. This suggests that brachytherapy needs to advance from a point-based (conventional) to a volume-based concept (3D conformal).
Article no. 608: PDF 
 
Spectroscopic study of dietary effects on volatile breath biomarkers
M. PETRUS, A.M. BRATU, C. POPA
Rom. Rep. Phys. 69, 609 (2017)
Abstract. The objective of the present research was to monitor the response of the organism to different food habits (mixed, vegetarian, raw vegan and Dukan) using a CO2 laser based photoacoustic spectroscopy technique (LPAS), a fast and precise method capable of detecting breath ethylene and ammonia biomarkers at low concentrations. Ethylene is a breath biomarker of oxidative stress and ammonia a breath biomarker of protein metabolism. Oxidative stress caused by a disturbance between free radicals and antioxidant defense remains as the major factor associated to the pathophysiology of many dysfunctions whereas ammonia originate in the amino acids catabolism and elevated breath ammonia can be associated with different diseases. The results reveal that the ethylene and ammonia breath biomarkers can be considered as a measure of wellness state in the involved volunteers. Implications for future research are also discussed.
Article no. 609: PDF 
 
A finite element method model to simulate the thermal response of vascularized tissue to laser irradation
P. BARVINSCHI, O.M. BUNOIU
Rom. Rep. Phys. 69, 610 (2017)
Abstract. In this study we developed a numerical model for calculating the heating effects of a laser beam on biological tissues, taking into considerations the cooling effects of flow in the blood vessels traversing the tissue. Because the laser radiation is supposed to be provided by a CO2 laser the volumetric heat source has a very small thickness at the surface of the tissue and it can be calculated using the Beer-Lambert's law. At the vessel entrance the blood flow is supposed to have a parabolic profile. The transient heat equation with a convection term was solved using the finite element method. A parametric study was conducted in order to see the effects of the blood flow network and laser parameters on the temperature field in the vascularized tissue. The results of the calculations suggest that the temperature distribution into the vascularized tissue depends on the laser power, laser spot size, blood vessels size and position, and blood flow rate.
Article no. 610: PDF 
 
 
ENVIRONMENTAL AND EARTH PHYSICS
 
Quantification of major ions in groundwaters using analytical techniques and statistical approaches
C. RADULESCU, A. POHOATA, P. BRETCAN, D. TANISLAV, C. STIHI, E.D. CHELARESCU
Rom. Rep. Phys. 69, 705 (2017)
Abstract. Groundwaters are used for domestic consumption, including drinking water, commercial, industrial as well as for irrigation. It is well known that the water-related health problems are the result of microbial and chemical contamination of drinking water. The main objective of this study was to determine quantitatively the contributions of various ground-water nitrate pollution sources including chemical fertilizers and animal wastes applied to croplands using the statistical approaches of PCA. In this respect, 240 wells water samples were collected from pre-existing wells, situated mainly in rural agricultural area from Targoviste Plain, Romania, between September and November 2014. Sampling was performed in according with EPA Guide for Ground-Water Sampling. Dissolved cations including Ca, Mg, Na, K, Cr, Fe, and Mn, were analysed using an iCAPTM Q ICP-MS. Dissolved anions (i.e. SO42-, NO3- and Cl-) were determined using Dionex ICS-3000 Ion Chromatography system. Alkalinity of groundwater samples was measured by titration method to quantify the carbonate species (mainly HCO3-). Quality control (QC) of chemical analyses was achieved by analyzing blanks duplicate samples. A statistical analysis of quantitative source apportionment for the chemical investigated elements was performed. The chemical parameters were interpreted with Principal Component Analysis (PCA). Pearson correlation coefficient matrix using a Student's t distribution in MatLab is used to determine the linear dependence between the analysed parameters. Schoeller diagram achieved with the RockWare AqQA program is presented for analysed ions (SO42-, HCO3-, Cl-, Ca2+, Mg2+) behavior interpretation. Durov Diagram is achieved as well, for a real interpretation of obtained data.
Article no. 705: PDF 
 
Vertical and temporal variation of aerosol mass concentration at Magurele - Romania during EMEP/PEGASOS campaign
M.M. CAZACU, O. TUDOSE, A. BOSCORNEA, L. BUZDUGAN, A. TIMOFTE, D. NICOLAE
Rom. Rep. Phys. 69, 706 (2017)
Abstract. Natural (volcanic activity, desert dust storms) and anthropogenic (fuel combustion, biomass burning etc.) aerosols play an important role in climate changes, as they influence the solar radiation balance on Earth through light scattering and absorption processes. Additionally, both natural (e.g. Saharan dust) and anthropogenic (urban traffic/industrial from big agglomerations aerosols) are acting as a trigger of the regional meteorology and weather forecast. This paper summarizes the temporal and vertical variation of mixed aerosol mass concentration near Bucharest, based on experimental data collected in the 2012 EMEP/PEGASOS campaign. From the series of experimental data collected we emphasize two cases, one for large biomass burning and one for a typical Saharan storm reaching the outskirts of Bucharest. The vertical mass concentrations profiles were determined based on the measurements performed with a multiwavelength depolarization Raman lidar. To assess the aerosol mass concentration using these lidar data, the authors are using the method proposed by Tesche et al., combined with forward simulations (i.e. OPAC). The results may contribute to describe, in an improved manner, the contribution of the mixed aerosols (low- or/and high-depolarizing particles) in the atmospheric simulations and models. It can also be used for operational purposes, such as near real time assessment of aerosol load (e.g. volcanic ash).
Article no. 706: PDF 
 
 
PHYSICS EDUCATION
 
Tools for scientific thinking - virtual laboratory for teaching physics
V. STEFANESCU, E.S. BARNA, GH. TOMSA
Rom. Rep. Phys. 69, 902 (2017)
Abstract. In the present work, we describes the software developed by the authors, designed and implemented for teaching and learning physics. The program combines a simple graphical user interface with a powerful engine that simulates the fundamental laws of Newtonian mechanics, requiring no programming skills. As the example, we present the result obtained at study the mathematical pendulum. The results are in excellent agreement with the theoretical predictions. Versatility and usability of the computer program make it suitable to be used in a virtual physics laboratory.
Article no. 902: PDF 
 

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