Hydrodynamical and radio evolution of young supernova remnant G1.9+0.3 based on the model of diffusive shock acceleration

The radio evolution of, so far the youngest known, Galactic supernova remnant (SNR) G1.9+0.3 is investigated by using three-dimensional (3D) hydrodynamic modelling and non-linear kinetic theory of cosmic ray (CR) acceleration in SNRs. We include consistent numerical treatment of magnetic field amplification (MFA) due to resonant streaming instability. Under the assumption that SNR G1.9+0.3 is the result of a Type Ia supernova explosion located near the Galactic Centre, using widely accepted values for explosion energy 10$^{51}$ erg and ejecta mass 1.4 $M_{\odot}$, the non-thermal continuum radio emission is calculated. The main purpose of this paper is to explain radio flux brightening measured over recent decades and also predict its future temporal evolution. We estimate that the SNR is now $\sim$ 120 yr old, expanding in an ambient density of 0.02 cm$^{-3}$, and explain its steep radio spectral index only by means of efficient non-linear diffusive shock acceleration (NLDSA). We also make comparison between simulations and observations of this young SNR, in order to test the models and assumptions suggested. Our model prediction of a radio flux density increase of $\sim$ 1.8 per cent yr$^{-1}$ during the past two decades agrees well with the measured values. We synthesize the synchrotron spectrum from radio to X-ray and it fits well the VLA, MOST, Effelsberg, Chandra and NuSTAR measurements. We also propose a simplified evolutionary model of the SNR in gamma rays and suggest it may be a promising target for gamma-ray observations at TeV energies with the future generation of instruments like Cherenkov Telescope Array. SNR G1.9+0.3 is the only known Galactic SNR with the increasing flux density and we present here the prediction that the flux density will start to decrease approximately 500 yr from now. We conclude that this is a general property of SNRs in free expansion phase.Comment: 16 pages, 11 figures, 1 table; corrected typos, updated reference

Is there a sociodemographic model of acceptance of postmaterialist values? The case of Serbia

The paper offers an analysis of the factors of acceptance of postmaterialist values in Serbia. In accordance with the assumptions of Ingleharťs postmaterialist value theory, but also on the basis of empirical works of his critics, the correlation between postmaterialist values and four sociodemographic variables: age, level of education, level of family income and population size of settlement, was analyzed. The data, collected in a 2007 public opinion research including 1410 citizens of Serbia aged 15-89, indicate that all the analysed factors are important, but that age is the best predictor of these values. The conclusion discusses the adequacy of generation hypothesis as a mechanism of changing predominant values in a society and the explanatory power of the analysed sociodemographic model

Microstructural changes initiated by sintering of refractory concrete based on recycled bauxite aggregate

Concretes whose structure and final properties are shaped during thermal pre-treatment or during life-service at elevated temperatures can be applied as construction material for thermal insulation and/or refractory linings in high-temperatureoperating plants. Refractory concretes designed with waste raw materials show satisfying performances in comparison with standard concretes. Sintering initiates microstructural changes within concrete. Concrete microstructure further develops with increasing temperature. Change progression can be monitored by means of destructive and non-destructive tests: either by investigating change of compressive strength or apparent porosity of concrete samples. Destructive tests, in this study, were applied in compressive strength investigation, while non-destructive tests were performed for results comparison. Experiment has been conducted on corundum (standard) concrete and recycled bauxite (experimental) concrete. Samples underwent thermal treatment from 110 to 1500°C. Macroperformance of the final refractory concrete was correlated to the microstructural change detected by means of XRD and SEM analysis. Creep testing was conducted to prove sintering process. Results showed that recycled concrete has equal if not better properties in comparison with standard refractory concrete and can be used as thermoinsulation or refractory material. The results presented in this paper contribute to the idea of including other testing methods (i.e. nondestructive methods) in investigation of microstructural changes and sintering process of refractory concrete. At the same time results of this investigation highlight advantages of application of secondary raw materials in design of refractory materials. Although recycled aggregate concrete showed lower compressive strength and higher porosity than commercial concrete it should be noted that both porosity and compressive strength are within satisfying value range for high-temperature application, i.e. these concretes will not be used as structural materials but as thermal insulation linings. In such application refractoriness is the property which is more important than strength. Considering the fact that compressive strength is above 50 MPa (and above 20 MPa at 1500°c) these concretes should be able to withstand load induced by other constructive parts of furnace and slag. Refractoriness test showed that bauxite-based recycled concrete is highly resistible on increasing temperatures and creep test showed initiation of sintering process. Corundum concrete can be used for temperature above 1500°c. Due to the satisfying performances it is concluded that recycled concrete can be equally used as standard concrete. Even though it has slightly lower properties, accent should be on the financial and ecological benefit found in using of recycled material and savings of energy and natural resources

Synthesis of BaTiO3 from a mechanically activated BaCO3-TiO2 system

In this article the solid state reaction of BaTiO3 formation from a mechanically activated BaCO3-TiO2 system has been investigated. An equimolar mixture of BaCO3 and TiO2 powders was activated in a planetary ball mill in a continual regime for 0, 30 and 90 min, pressed and thermally treated up to 1200°C. The effect of the milling and firing regime on the phase formation was investigated by the X-ray diffraction (XRD) method and differential thermal analysis (DTA). Deconvolution of the experimental DTA curve corresponding to the BaTiO3 synthesis process has been performed. The influence of the activation time on the change of characteristic temperature for each elementary step in the complete solid-state reaction of BaTiO3 formation, was analyzed. These results were correlated with the ones obtained by SEM characterization and by XRD analysis.U ovome radu je analiziran uticaj mehaničke aktivacije sistema BaCO3- TiO2 na formiranje BaTiO3. Ekvimolarne smeše praha BaCO3 i TiO2 su aktivirane u planetarnom mlinu u kontinualnom režimu tokom 0, 30 i 90 min. Uzorci su zatim presovani i termički tretirani do 1200oC. Efekat mlevenja i zagrevanja na promene faza je analiziran primenom rendgenske fazne analize i diferencijalne termijske analize. Izvršena je dekonvolucija eksperimentalno dobijene DTA krive koja odgovara procesu sinteze BaTiO3, kao i analiza uticaja vremena aktivacije na promene karakteristične temperature za svaki pojedinačni elementarni proces tokom sinteze barijum titanata. Ovi rezultati su korelisani sa rezultatima dobijenim SEM i XRD analizom

The effect of pharmacological treatment on the occurren ceof depressive disorder in patients with chronic hepatitis C

Uvod. Hronični hepatitis C je široko rasprostranjena, teška, evolutivna bolest koja predstavlja veliki javno-zdravstveni problem. Globalna prevalencija se procenjuje na oko 3% populacije. Aktuelni standardni tretman za hronični hepatitis C sastoji se u lečenju pegilovanim interferonom alfa, subkutano, jedanput nedeljno, u kombinaciji sa oralnim ribavirinom, koji se daje svakodnevno. Primenjuje se u trajanju od 48 ili 24 nedelje. Terapija interferonom je povezana sa značajnim psihijatrijskim neželjenim efektima, a najznačajnija je pojava depresivne simptomatologije. Ciljevi. Utvrđivanje učestalosti i težine depresivne simptomatologije kod osoba obolelih od hroničnog hepatitisa C na terapiji pegilovanim interferonom alfa-2a u kombinaciji s ribavirinom; komparacija rezultata učestalosti i težine depresivne simptomatologije kod osoba obolelih od hroničnog hepatitisa C na navedenoj terapiji tokom 72 nedelje ispitivanja i kontrolne grupe koju sačinjavaju osobe obolele od iste bolesti, a bez navedene terapije u istom vremenskom periodu ispitivanja; komparacija povezanosti faktora rizika za pojavu depresivnosti kod obe grupe ispitanika; analiza uticaja utvrđenih faktora rizika na razvoj depresivnosti kod obe grupe ispitanika; preporuke tretmana sa psihijatrijskog aspekta na osnovu dobijenih rezultata. Hipoteze. Postoji statistički značajna razlika u učestalosti i težini depresivne simptomatologije kod osoba obolelih od hroničnog hepatitisa C na terapiji pegilovanim interferonom alfa-2a u kombinaciji sa ribavirinom tokom 72 nedelje ispitivanja i kontrolne grupe u istom vremenskom periodu ispitivanja; postoji pozitivna korelacija između faktora rizika i depresivnosti kod osoba obolelih od hroničnog hepatitisa C na navedenoj terapiji; prisustvo psihijatrijskih poremećaja u anamnezi i ženski pol predstavljaju prediktore za razvoj depresivnosti kod osoba obolelih od hroničnog hepatitisa C na navedenoj terapiji...Introduction. Chronic hepatitis C is a widely distributed severe evolutive disease that is a great public health problem. The global prevalence is estimated at 3% of the population. The current standard treatment of chronic hepatitis C consists of pegylated interferon alpha, subcutaneously, once a week combined with oral ribavirin, taken every day. It is applied in the duration of 24 or 48 weeks. Interferon therapy is associated with significant psychiatric side effects, the most of them being depressive symptomatology. Aims. The aims of the study were to establish frequency and severity of the depression in patients with chronic hepatitis C with pegylated interferon alpha-2a combined with ribavirin (PEG-IFN-α-2a+RBV); to compare the frequency and the severity of depressive symptoms in chronic hepatitis C patients in the PEG-IFN-α-2a+RBV and in the control group consisting of the patients with same disease without the PEG-IFN-α- 2a+RBV, respectively, after 72 weeks of the observation; to compare the association of the depression risk factors in chronic hepatitis C patients in the aforementioned therapy and in the control group, respectively; and to assess the effects of the predictors on the development of depression in chronic virus hepatitis C in the PEG-IFN-α-2a+RBV and in the control group, respectively. Hypothesis. There is a statistically significant difference in the frequency and severity of depression in chronic hepatitis C patients in the aforementioned therapy and the control group after 72 weeks of observation, respectively; there is a positive correlation between specific risk factors and depression in chronic hepatitis C patients in the aforementioned therapy; the presence of lifetime psychiatric disorders and female sex are significant predictors for development of depression in chronic hepatitis C patients in the aforementioned therapy..

Synthesis and sintering of high-temperature composites based on mechanically activated fly ash

Amount of fly ash which is and yet to be generated in the coming years highlights the necessity of developing new methods of the recycling where this waste can be reused in significant quantity. A new possibility for fly ash utilization is in high-temperature application (thermal insulators or/and refractory material products). As such, fly ash has to adequately answer the mechanical and thermal stability criteria. One of the ways of achieving it is by applying mechanical activation procedure on fly ash. In present study, fly ashes from two different power plants were mechanically activated in a planetary ball mill. Mechanically treated fly ashes were cemented with two different binders: standard Portland cement and high-aluminates cement. Physico-chemical analysis and investigation of mineralogical components of composites are emphasized, due to the changes occurred in fly ash during mechanical activation and sintering of composites. Macro-performance of the composites was correlated to the microstructure of fly ash studied by means of XRD and SEM analysis. Thermal stability of crystalline phases was investigated with DTA. Highlight was placed on determination of relationship between mechanically activated fly ash and obtained composites microstructure on one side and behavior of sintered composites on the other side. [Projekat Ministarstva nauke Republike Srbije, br. 172057, 45008 and a project F-198, financed by Serbian Academy of Sciences and Arts

Updated radio Σ−D\Sigma-D relation for Galactic supernova remnants

We present updated empirical radio surface-brightness-to-diameter ($\Sigma-D$) relation for supernova remnants (SNRs) in our Galaxy. Our original calibration sample of Galactic SNRs with independently determined distances (Pavlovic et al. 2013, hereafter Paper I) is reconsidered and updated with data which became available in the past two years. The orthogonal fitting procedure and probability-density-function-based (PDF) method are applied to the calibration sample in the $\log \Sigma - \log D$ plane. Orthogonal regression keeps $\Sigma-D$ and $D-\Sigma$ relations invariant. Our previous Monte Carlo simulations verified that the slopes of the empirical $\Sigma-D$ relation should be determined by using orthogonal regression. Updated calibration sample contains 65 shell SNRs. 6 new Galactic SNRs are added to the sample from Paper I, one is omitted and distances are changed for 10 SNRs. The slope derived here is slightly steeper ($\beta \approx 5.2$) than $\Sigma-D$ slope in Paper I ($\beta \approx 4.8$). The PDF method relies on data points density maps which can provide more reliable calibrations that preserve more information contained in the calibration sample. We estimate distances to five new faint Galactic SNRs discovered for the first time by Canadian Galactic Plane Survey and obtained distances of 2.3, 4.0, 1.3, 2.9 and 4.7 kiloparsecs for G108.5+11.0, G128.5+2.6, G149.5+3.2, G150.8+3.8 and G160.1$-$1.1, respectively. The updated empirical relation is used to estimate distances of 160 shell Galactic SNRs and new results change their distance scales up to 15 per cent, compared to results from Paper I. The PDF calculation can provide even few times higher or lower values in comparison with orthogonal fit, as it uses totally different approach. However, in average, this difference is 32, 24 and 18 per cent for mode, median and mean distances.Comment: 17 pages, 3 figures, Accepted for publication in Serbian Astronomical Journa