241 research outputs found

    On the Detectability of CMB Anisotropies Induced by de Sitter-G\"odel-de Sitter Phase Transition

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    A geometrical phase transition in the very early Universe, from de Sitter to G\"odel and back to de Sitter (dGd) spacetimes, can explain the universal phenomenon of rotation of many large scale structures. This phase transition is shown to induce fluctuations on the matter and radiation fields with possibly observable traces. In this work we simulate the dGd-induced inhomogeneities and use their power spectrum, parametrized by the parameter pair (p1,p2p_1, p_2), as possible seeds of CMB anisotropies along with the standard inflationary perturbations. With the Planck 2018 observations, we find p1=0.008−0.008+0.003p_1=0.008^{+0.003}_{-0.008} and p2=0.002−0.002+0.001p_2= 0.002^{+0.001}_{-0.002} consistent with pure inflationary power spectrum and no hint for the dGd transition. Future large scale surveys can further tighten the constraints and probe the physics of the early Universe

    On the classification of consistent boundary conditions for f(R) \mathit{f}(\mathit{R})-Gravity

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    Using a completely covariant approach, we discuss the role of boundary conditions (BCs) and the corresponding Gibbons--Hawking--York (GHY) terms in f(R) \mathit{f}(\mathit{R}) -gravity in arbitrary dimensions. We show that f(R) f(\mathit{R}) -gravity, as a higher derivative theory, is not described by a degenerate Lagrangian, in its original form. Hence, without introducing additional variables, one can not obtain consistent BCs, even by adding the GHY terms (except for f(R)=Rf(\mathit{R})=R). However, following the Ostrogradsky approach, we can introduce a scalar field in the framework of Brans-Dicke formalism to the system to have consistent BCs by considering appropriate GHY terms. In addition to the Dirichlet BC, the GHY terms for both Neumann and two types of mixed BCs are derived. We show the remarkable result that the f(R)f(\mathit{R})-gravity is itself compatible with one type of mixed BCs, in DD dimension, i.e. it doesn't require any GHY term. For each BC, we rewrite the GHY term in terms of Arnowit-Deser-Misner (ADM) variables.Comment: 21 page

    Complete Treatment of Compost Leachate Using Integrated Biological and Membrane Filtration Processes

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    A lab-scale SBR equipped with a flat sheet membrane in submerged configuration that is named MSBR was used for treatment of composting leachate. It was fed by biologically treated leachate with overall 70-1360 mg/L Chemical Oxygen Demand (COD). The values of pH, Electrical Conductivity (EC), and Dissolved Oxygen (DO) were monitored routinely. However, analysis of total COD, Soluble COD (SCOD), Biological Oxygen Demand (BOD5), Total Suspended Solids (TSS) and Volatile Suspended Solids (VSS) were done in feed and filtrate, whenever the system reached steady state twice a week for about 6 months. In all loading rate, BOD5 concentration was less than standard limit. The removal efficiency of total COD increased in bioreactor with time in all experiments was up to 80%. Influent SCOD varied spectacularly (50-1050 mg/L) due to the leachate collection during different seasons but in the effluent it remained relatively stable. About 60% of the feed SCOD was non biodegradable type that was separated by the membrane. Up to 99 % further solids was removed with micro pore membrane which might be mainly included in colloidal solids. The value of EC for the leachate sample was 0.86-4 mS/cm in 22 degrees C which decreased by membrane significantly. It was concluded that, MSBR as a versatile technology with high throughput could treat composting leachate below the standard limit if used after proper processes

    Environmental mycobacteria in areas of high and low tuberculosis prevalence in the Islamic Republic of Iran

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    This research compared the numbers and types of different Mycobacterium species in soil samples taken from 2 areas of Golestan province, Islamic Republic of Iran, 1 with a high prevalence of tuberculosis and 1 with a low prevalence. From 220 samples, 91 grew positive cultures (41.4%) and 161 different strains were diagnosed. The most common species isolated were Mycobacterium fortuitum, M. flavescens and M. chelonae. The frequencies of environmental Mycobacterium in the low-prevalence area were much higher than in the high-prevalence area, perhaps due to different environmental factors

    Complications leading to hospitalization due to consumption of anti-TB drugs in patients with tuberculosis in Gorgan, Iran (2007-12)

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    Background and Objective: Anti tuberculosis drugs therapy is the most effective method for controling the tuberculosis (TB). Early detection and appropriate treatment can prevent the TB-drug resistance. This study was carried out to determine the complications leading to hospitalization due to consumption of anti-TB drugs in patients with tuberculosis. Methods: In this descriptive-analytic study, 1550 records of patients with TB in urban and rural health centers of Gorgan, north of Iran were assessed during 2007-12. Checklist consists of demographic and clinical data for each patient was recorded in a questionare. Results: 44 cases experienced the complications of anti-TB drugs. 27 (61.4%) of cases with complications were women. 77.3% and 22.7% of patients affected with pulmonary and extra pulmonary tuberculosis,respectively. 38.6% of patients were diabetic. The hepatic complication was seen in 37 cases (84.1%). Skin and other complications were seen in 5 and 2 cases, respectively. There was not any relationship between drug complications and other disases. Conclusion: Hepatic damage is the most common complication leading to hospitalization in tuberculosis patients using anti-TB drugs. Keywords: Tuberculosis, Anti-TB drug, Live

    Correlation between hepatitis B G1896A precore mutations and HBeAg in chronic HBV patients

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    Background: Hepatitis B virus (HBV) infection is an important health concern worldwide, with critical outcomes. Hepatitis B e antigen (HBeAg) negative chronic hepatitis B is frequently caused by a mutation (G1896A) in the hepatitis B virus (HBV) precore (PC) reading frame, which creates a stop codon, causing premature termination of the HBe protein. Objectives: This study aimed to investigate the G1896A PC mutation and its effect on HBeAg detection in chronic HBV patients. Patients and Methods: In this study, 120 chronic HBV patients neither vaccinated or who had benefited from immunoglobulin therapy, were recruited. The HBV-DNA was extracted from plasma and polymerase chain reaction (PCR) was performed. Positive PCR products were subjected to automated sequencing. The HBV serological markers hepatitis B s antigen (HBsAg), HBeAg were tested. Results: One hundred out of 120 (83.3%) patients were HBeAg negative and 100% were HBsAg positive. The comparison of nucleotide sequences with the reference sequence (Accession number: AB033559) in HBeAg negative patients showed that there was a high rate of mutations in G1896A (93.18%). Conclusions: This study indicates that the rate of G1896A mutation at the PC region among HBeAg negative patients, in the Golestan province of Iran, was similar to the average rate encountered in other parts of Iran. The PC stop codon mutation was detected in 93.18% of HBeAg negative patients. Further studies with larger sample sizes are required to elucidate the exact role of these mutations in the clinical course of chronic HBV infection. © 2015, Ahvaz Jundishapur University of Medical Sciences

    Investigation of anaerobic biodegradability of real compost leachate emphasis on biogas harvesting

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    Anaerobic treatability of real compost leachate was assessed using laboratory-scale anaerobic sequencing batch reactor at mesophilic conditions. Interventional study was conducted at wide range of organic loading rate 0.93-25 g l(-1) day(-1) by varying hydraulic retention times 23 and 12 h. Initial chemical oxygen demand (COD) was 1.85-25 g l(-1). pH variations; total, soluble (SCOD), readily biodegradable (rbCOD) chemical oxygen demand; volatile fatty acids degradation; biogas production; and methane fraction were considered in this study. The organic matter removal efficiencies were in the range of 76-81 % depending on loading rates applied. The maximum volumetric methane production rate of 5.7 l CH4 l(-1) day(-1) was achieved at the loading rate of 19.65 g l(-1) day(-1). About 85 % of removed organic matters during the biodegradation were converted to the methane. The results have shown that the anaerobic batch reactor could be an appealing option for changing compost leachate into the useable products such as biogas and other energy-rich compounds, which may play a serious role in meeting the world's ever-increasing energy requirements in the future

    Investigation of PCB removal by single walled carbon nanotube (0, 14)

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    Background and aims: High heat capacity and low reactivity of polychlorinated biphenyls have caused to remain their herbs in the environment from a few decades. Accumulation of these pollutants in animal tissues leads to genetic mutationsas and exposure to them will accelate the trend of getting these chronic deseases. During the recent years, removal of PCBs from natural ecosystems has been considered as one of the environmental chalanges. The aim of this theoretical study was to investigate the ability of the special kind of carbon nanotubes for removal and identification of the hazardous type of PCBs. Methods: The current study investigates PCB-153 removal by using computational nanotechnology: So, this theoretical study by using semi-empirical MNDO, analysis and obsorption of PCB-153 in interactions with the wall of carbon nanotubes single-walled zigzag (0, 14) during two 6-step process has similarized and computed. The first six stages included decomposition of pollutants in middle level (Trichlorobenzene 1,2,4), and the second six stages contained calculations related to middle defeat in final products (1,2-chloropropane and 1-chloropropane). Results: During the two studied interactions, the total energy, Gibbs free energy, dependence of energy and enthalpy show a considerable decrease in the transition phase. Moreover, parameters of nuclear energy and bipolar disorder in the transition phase shows a significant increase in their amounts. Also, the conductivity of nanotubes in absorption time and decomposition of pollutants and the amount of intermediate increases considerable. Conclution: The thermodynamic parameters obtained from the interaction shows that the chemical absorption reaction of PCB-153 and its removal using the examined carbon nanotube can be done spontaneously, and this zigzag nanotube may be a suitable tool for detection and analysis for the pollutant of PCB-153

    SYNTHESIS OF MAGNETITE NANOPARTICLES AND EVALUATION OF ITS EFFICIENCY FOR ARSENIC REMOVAL FROM SIMULATED INDUSTRIAL WASTEWATER

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    In this study the efficiency of magnetic nanoparticles for removal of trivalent arsenic from synthetic industrial wastewater was evaluated. The nanoparticles was prepared by sol-gel method and characterized by X-ray methods including XRD, XRF, and SEM, and vibrating sample magnetometer (VSM). The results showed that synthesized nanoparticles were in the size range of 40-300 nm, purity of about 90%, and magnetization of nanoparticles was 36.5emu/g. In initial conditions including: pH=7, As(III) concentration of 10 mg/L, nanomagnetite concentration of 1g/L, shaking speed of 250 rpm and 20 minute retention time, 82% of As (III) was removed. Competition from common coexisting ions such as Na+, Ni2+, Cu2+, SO42-, and Cl- was ignorable but for NO3- was significant. The adsorption data of magnetite nanoparticles fit well with Freundlich isotherm equations. The adsorption capacity of the Fe3O4 for As (Ill) at pH=7 was obtained as 23.8 mg/g. It was concluded that magnetite nanoparticles have considerable potential in removal of As(III) from synthetic industrial wastewaters
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