2,016 research outputs found
A New Concept of Transonic Galactic Outflows in a Cold Dark Matter Halo with a Central Super-Massive Black Hole
We study fundamental properties of isothermal, steady and spherically
symmetric galactic outflow in the gravitational potential of a cold dark matter
halo and a central super-massive black hole. We find that there are two
transonic solutions having different properties: each solution is mainly
produced by the dark matter halo and the super-massive black hole,
respectively. Furthermore, we apply our model to the Sombrero galaxy. In this
galaxy, Chandra X-ray observatory detected the diffuse hot gas as the trace of
galactic outflows while the star-formation rate is low and the observed gas
density distribution presumably indicates the hydrostatic equilibrium. To solve
this discrepancy, we propose a solution that this galaxy has a transonic
outflow, however, the transonic point forms in a very distant region from the
galactic center (? 127 kpc). In this slowly accelerated transonic
outflow, the outflow velocity is less than the sound velocity for most of the
galactic halo. Since the gas density distribution in this subsonic region is
similar to the hydrostatic one, it is difficult to distinguish the wide
subsonic region from hydrostatic state. Such galactic outflows are dfferent
from the conventional supersonic outflows observed in star-forming galaxies.Comment: 7 pages, 3 figures, accepted for publication in JPS Conference
Proceedings. arXiv admin note: substantial text overlap with arXiv:1405.345
Recommended from our members
An unusual cause of gynaecomastia in a male
Summary: Beta-human chorionic gonadotropin (βhCG) is normally produced by syncytiotrophoblasts of the placenta during pregnancy and aids embryo implantation. However, it is also secreted in varying amounts in non-pregnant conditions commonly heralding a neoplastic process. We present a case of 50-year-old man, who presented with bilateral gynaecomastia with elevated testosterone, oestradiol, suppressed gonadotropins with progressively increasing levels of human chorionic gonadotropin (hCG). Biochemical and radiological investigations including ultrasonography of testes, breast tissue, MRI pituitary and CT scan full body did not identify the source of hCG. FDG PET scan revealed a large mediastinal mass with lung metastasis. Immunostaining and histological analysis confirmed the diagnosis of primary choriocarcinoma of the mediastinum. It is highly aggressive and malignant tumor with poor prognosis. Early diagnosis and management are essential for the best outcome. Learning Points: High βhCG in a male patient or a non-pregnant female suggests a paraneoplastic syndrome. In the case of persistently positive serum hCG, exclude immunoassay interference by doing the urine hCG as heterophilic antibodies are not present in the urine. Non-gestational choriocarcinoma is an extremely rare trophoblastic tumor and should be considered in young men presenting with gynaecomastia and high concentration of hCG with normal gonads. A high index of suspicion and extensive investigations are required to establish an early diagnosis of extra-gonadal choriocarcinoma. Early diagnosis is crucial to formulate optimal management strategy and to minimize widespread metastasis for best clinical outcome
Design and implementation of an oil leakage monitoring system based on wireless network
Monitoring pipeline leaks is one of the recent hot studies. Leakage may occur because of time corrosion in the tube raw materials. To reduce the negative consequences of this leak, an effective leak detection system is used to prevent serious leakage accidents and damage in oil pipelines. Buildings, ecosystems, air pollution, and human life are all at risk in case of leakage occurs which could lead to fires. This paper introduces one of the research methods for the detection of pipeline leaks with a particular focus on software-based methods. The computer board interface (CBI) and wireless sensor networks have been used beside Arduino as a micro-monitor for the entire system. ZigBee is also utilized to send read data from sensors to the monitoring system displayed on the LabVIEW graphical user interface (GUI). The operator can take direct action when a leak occurs. The effectiveness of the leakage monitoring process and its practical use are demonstrated by the introduction of computerized techniques based on pressure gauge analysis on a specific pipeline in the laboratory. The result showed that the system is widely covered, accurate data transmission and robust real-time performance which reduces economic losses and environmental pollution
Corrosion, Passivity and Pitting of Inconel (600) in Sulphuric Acid
A potentiostatic study of the behaviour of Inconel (600) in molar sulphuric acid has been carried out over the temperature range 293-313 K. Values have been established for the potentials and current densities of the corrosion, active-passive transition, passivity and transpassive states. For corrosion, the current density (ic) and potential (Ec) have been determined from well-defined Tafel lines. The potential and current density prior to the commencement of passivity have been obtained corresponding respectively to the critical potential (Ecr( and to the current density (icr) for the active-passive transition state. The passive range was defined by the respective potentials and current densities for passive film formation and dissolution. The dissolution point was correlated with transpassive potential (Et) and current density (it). All the estimated potentials and current densities for the various states were influenced by temperature and the presence of additives in the sulphuric acid. Additives such as nitric acid, thiourea and sodium chloride lowered the corrosion current density (ic) of the alloy while hydrochloric acid enhanced the value of ic. Addition of thiourea or sodium chloride or hydrochloric acid caused a shift in the corrosion potential (Ec) to less negative values while nitric acid shifted Ec to more negative potentials. The kinetic effect of the additives have been studies. Values of activation energy (E) were considered to be apparent and some negative values of E have been obtained with certain additives for the critical and passivity processes. Such negative E values were attributed to small values of true energies of activation together with relatively large exothermic enthalpies of such processes
COMPARATIVE PHARMACOGNOSTICAL STUDY OF THE GENUINE AND MARKET SAMPLES OF THE STEM BARK OF CIRABILWA (HOLPTELEA INTEGRIFOLIA PLANCH.)
Context: The stem bark of Cirabilwa (Holoptelea integrifolia Planch.) is used for treating various disease conditions including Dyspepsia, Flatulence, Colic, Helminthiasis, Vomiting, Skin diseases, Diabetes Mellitus, Haemorrhoids and Rheumatism in traditional system of medicine since ancient times. As a part of a proposed clinical study, sufficient quantity of the plant drug was required to evaluate the antidyslipidemic effects, which was procured from market. Aim: This study was designed to identify and compare the pharmacognostical features of the genuine hand collected samples and market samples of the stem bark of this medicinal plant, so as to prove the genuinity of the market samples before using it for clinical study. Materials and Methods: Macroscopic and microscopic methods were applied to determine the diagnostic features of the shade dried samples of the intact stem bark of both samples of the drug and was compared with the available data. Results: The shape, color, thickness, odour, consistency, fracture and surface characteristics were determined. Compound microscope images showed the presence of ray cells, stone cells, starch grains, rhomboidal crystals in both the samples. Conclusion: The study confirmed the identity of both genuine and market samples. Comparable results were obtained which proved the genuinity of the market samples of the stem bark of Cirabilwa (Holoptelea integrifolia Planch)
Thermodynamic and Kinetic Study of the Adsorption of Pb (II) from Aqueous Solution Using Bentonite and Activated Carbon
The adsorption of Pb(II) ions onto bentonite and activated carbon was investigated. The effects of pH, initial adsorbent dosage, contact time and temperature were studied in batch experiments. The maximum adsorption capacities for bentonite and activated carbon were 0.0364 and 0.015 mg/mg, respectively. Thermodynamic parameters such as Gibbs free energy change, Enthalpy change and Entropy change have been calculated. These thermodynamic parameters indicated that the adsorption process was thermodynamically spontaneous under natural conditions and the adsorption was endothermic in nature. Experimental data were also tested in terms of adsorption kinetics, the results showed that the adsorption processes followed well pseudo second- order kinetics
- …