479 research outputs found

    An Empirical Relation Between The Large-Scale Magnetic Field And The Dynamical Mass In Galaxies

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    The origin and evolution of cosmic magnetic fields as well as the influence of the magnetic fields on the evolution of galaxies are unknown. Though not without challenges, the dynamo theory can explain the large-scale coherent magnetic fields which govern galaxies, but observational evidence for the theory is so far very scarce. Putting together the available data of non-interacting, non-cluster galaxies with known large-scale magnetic fields, we find a tight correlation between the integrated polarized flux density, S(PI), and the rotation speed, v(rot), of galaxies. This leads to an almost linear correlation between the large-scale magnetic field B and v(rot), assuming that the number of cosmic ray electrons is proportional to the star formation rate, and a super-linear correlation assuming equipartition between magnetic fields and cosmic rays. This correlation cannot be attributed to an active linear alpha-Omega dynamo, as no correlation holds with global shear or angular speed. It indicates instead a coupling between the large-scale magnetic field and the dynamical mass of the galaxies, B ~ M^(0.25-0.4). Hence, faster rotating and/or more massive galaxies have stronger large-scale magnetic fields. The observed B-v(rot) correlation shows that the anisotropic turbulent magnetic field dominates B in fast rotating galaxies as the turbulent magnetic field, coupled with gas, is enhanced and ordered due to the strong gas compression and/or local shear in these systems. This study supports an stationary condition for the large-scale magnetic field as long as the dynamical mass of galaxies is constant.Comment: 23 pages, 4 figures, accepted for publication in the Astrophysical Journal Letter

    Integrated Treatment of Saline Oily Wastewater Using Sono-Electrokinetic Process, Degradation Mechanism, and Toxicity Assessment

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    Integration of sonication (US) with electrokinetic (EK) oxidation was studied for the treatment of a saline oily wastewater, as well as the effect of operating parameters, including pH, voltage, electrode distance (ED), sonication power, and reaction time on COD removal. A COD removal of 98 % was observed for the sono-electrokinetic (SEK) process with an applied voltage of 2.5 V, US power of 300 W, initial COD concentration of 3850 mg L–1, and reaction time of 9 h. The efficiency of SEK over sonication alone and EK oxidation alone was also confirmed with a higher pseudo-first-order reaction rate constant of 0.43 h–1, compared to values of 0.13 and 0.01 for alternative processes. In addition, the biodegradability of effluent was improved based on average oxidation state (AOS) and carbon oxidation state (COS) analysis. Oxygen consumption rate inhibition, dehydrogenase activity inhibition, and growth rate inhibition methods demonstrated the low toxicity of effluent (12–15 %) compared to influent. The current work indicated that SEK is a reliable and efficient technology for the treatment of saline oily wastewaters containing recalcitrant aromatic organics. This work is licensed under a Creative Commons Attribution 4.0 International License

    Cross-Cultural Adaptations of the MacArthur Competence Assessment Tool for Treatment in Iran

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    Background: According to general ethical and legal principles, valid consent must be obtained before starting any procedure. Objectives: Due to the lack of a standard tool for assessing patients’ capacity to consent to medical treatment in Iran, the present study was carried out aiming to devise a Persian version of a cross-cultural adaptation of the MacArthur competence assessment tool. Patients and Methods: By reviewing different methods of cultural translation and adaptation for assessment tools, and due to the lack of consensus on its processes, we selected Wild’s model as one of the most comprehensive methods in this regard. Wild’s (2005) 10-stage model includes preparation, forward translation, reconciliation of the forward translation, back translation of reconciliation, back translation review, cognitive debriefing and cognitive review, and finalization, proofreading and final reporting. Using this model, we translated the MacArthur assessment tool and made it adaptable to Iranian patients. Results: The MacArthur assessment tool is not dependent on any specific culture and language. As a result, if translation and its scientific adaptation are done based on an integrated and detailed model, the tool can be used for every culture and language. In other words, this tool is not culture-specific; so, it is applicable in cases where a translation is needed, and it can be culturally adapted to suit different societies. Conclusions: In the present study, we are able to focus on and prove the efficacy and benefits of this measurement tool

    Cool and warm dust emission from M33 (HerM33es)

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    We study the far-infrared emission from the nearby spiral galaxy M33 in order to investigate the dust physical properties such as the temperature and the luminosity density across the galaxy. Taking advantage of the unique wavelength coverage (100, 160, 250, 350 and 500 micron) of the Herschel Space Observatory and complementing our dataset with Spitzer-IRAC 5.8 and 8 micron and Spitzer-MIPS 24 and 70 micron data, we construct temperature and luminosity density maps by fitting two modified blackbodies of a fixed emissivity index of 1.5. We find that the 'cool' dust grains are heated at temperatures between 11 and 28 K with the lowest temperatures found in the outskirts of the galaxy and the highest ones in the center and in the bright HII regions. The infrared/submillimeter total luminosity (5 - 1000 micron) is estimated to be 1.9x10^9 Lsun. 59% of the total luminosity of the galaxy is produced by the 'cool' dust grains (~15 K) while the rest 41% is produced by 'warm' dust grains (~55 K). The ratio of the cool-to-warm dust luminosity is close to unity (within the computed uncertainties), throughout the galaxy, with the luminosity of the cool dust being slightly enhanced in the center of the galaxy. Decomposing the emission of the dust into two components (one emitted by the diffuse disk of the galaxy and one emitted by the spiral arms) we find that the fraction of the emission in the disk in the mid-infrared (24 micron) is 21%, while it gradually rises up to 57% in the submillimeter (500 micron). We find that the bulk of the luminosity comes from the spiral arm network that produces 70% of the total luminosity of the galaxy with the rest coming from the diffuse dust disk. The 'cool' dust inside the disk is heated at a narrow range of temperatures between 18 and 15 K (going from the center to the outer parts of the galaxy).Comment: 12 pages, 14 figures, accepted for publication in A&

    Dietary intake and lifestyle behavior in different phenotypes of polycystic ovarian syndrome: a case-control study

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    Objective: To compare dietary intake and lifestyle behaviour in women with polycystic ovarian syndrome (PCOS) and healthy women. Methods: 160 healthy women (partner with male infertility) were recruited to a control group; 168 women with PCOS (diagnosed on ultrasound) were recruited to a case study group for this cross-sectional comparative study. The case group was classified into three phenotypes based on presence or absence of menstrual disorder (M), hyperandrogenism (HA), and polycystic ovary according to sonography (PCO): HA+PCO (n=53), PCO+M (n=57) and M+HA+PCO (n=66). Dietary intake and lifestyle behaviour were measured using a food frequency questionnaire (FFQ) and a lifestyle questionnaire (LQ). Results: The mean energy (P<0.001) and fat intake (P<0.001) were greater in PCOS groups compared with the control group. The average energy and fat intake were greater in HA+M+PCO group after age and BMI adjustment compared with other phenotypes (P<0.001). In comparison with the control group, lifestyle scores were lower in the PCOS group in the fields of physical activity, weight and nutrition control after age and BMI adjustment (P<0.001). The average score of lifestyle in the fields of physical activity, weight and nutrition control, and psychological health was lower in the phenotype HA+M+PCO compared with other phenotypes (P<0.001). Conclusions: Limited energy and fat intake is strongly recommended in Iranian women with PCOS especially in phenotype HA+M+PCO. Consultation on improvement of psychological health and the importance of weight and nutrition control, and appropriate physical activity in patients especially in HA+M+PCO is advocated. Keywords: Lifestyle, polycystic ovarian syndrome, die

    The Ionized Gas in Nearby Galaxies as Traced by the [NII] 122 and 205 \mu m Transitions

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    The [NII] 122 and 205 \mu m transitions are powerful tracers of the ionized gas in the interstellar medium. By combining data from 21 galaxies selected from the Herschel KINGFISH and Beyond the Peak surveys, we have compiled 141 spatially resolved regions with a typical size of ~1 kiloparsec, with observations of both [NII] far-infrared lines. We measure [NII] 122/205 line ratios in the ~0.6-6 range, which corresponds to electron gas densities nen_e~1-300 cm3^{-3}, with a median value of nen_e=30 cm3^{-3}. Variations in the electron density within individual galaxies can be as a high as a factor of ~50, frequently with strong radial gradients. We find that nen_e increases as a function of infrared color, dust-weighted mean starlight intensity, and star formation rate surface density (ΣSFR\Sigma_{SFR}). As the intensity of the [NII] transitions is related to the ionizing photon flux, we investigate their reliability as tracers of the star formation rate (SFR). We derive relations between the [NII] emission and SFR in the low-density limit and in the case of a log-normal distribution of densities. The scatter in the correlation between [NII] surface brightness and ΣSFR\Sigma_{SFR} can be understood as a property of the nen_e distribution. For regions with nen_e close to or higher than the [NII] line critical densities, the low-density limit [NII]-based SFR calibration systematically underestimates the SFR since [NII] emission is collisionally quenched. Finally, we investigate the relation between [NII] emission, SFR, and nen_e by comparing our observations to predictions from the MAPPINGS-III code.Comment: 18 pages, 9 figures, accepted for publication in The Astrophysical Journa

    A Detailed Study of the Radio--FIR Correlation in NGC6946 with Herschel-PACS/SPIRE from KINGFISH

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    We derive the distribution of the synchrotron spectral index across NGC6946 and investigate the correlation between the radio continuum (synchrotron) and far-infrared (FIR) emission using the KINGFISH Herschel PACS and SPIRE data. The radio--FIR correlation is studied as a function of star formation rate, magnetic field strength, radiation field strength, and the total gas surface brightness. The synchrotron emission follows both star-forming regions and the so-called magnetic arms present in the inter-arm regions. The synchrotron spectral index is steepest along the magnetic arms (αn1\alpha_n \sim 1), while it is flat in places of giant H{\sc ii} regions and in the center of the galaxy (αn0.60.7\alpha_n \sim 0.6-0.7). The map of αn\alpha_n provides an observational evidence for aging and energy loss of cosmic ray electrons propagating in the disk of the galaxy. Variations in the synchrotron--FIR correlation across the galaxy are shown to be a function of both star formation and magnetic fields. We find that the synchrotron emission correlates better with cold rather than with warm dust emission, when the interstellar radiation field is the main heating source of dust. The synchrotron--FIR correlation suggests a coupling between the magnetic field and the gas density. NGC6946 shows a power-law behavior between the total (turbulent) magnetic field strength B and the star formation rate surface density ΣSFR\Sigma_{\rm SFR} with an index of 0.14\,(0.16)±\pm0.01. This indicates an efficient production of the turbulent magnetic field with the increasing gas turbulence expected in actively star forming regions. The scale-by-scale analysis of the synchrotron--FIR correlation indicates that the ISM affects the propagation of old/diffused cosmic ray electrons, resulting in a diffusion coefficient of D0=4.6×1028D_0=4.6\times 10^{28}\,cm2^2\,s1^{-1} for 2.2\,GeV CREs.Comment: 23 pages, 13 figures, accepted for publication in Astronomy & Astrophysics Journa

    A far-IR view of the starburst driven superwind in NGC 2146

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    NGC 2146, a nearby luminous infrared galaxy (LIRG), presents evidence for outflows along the disk minor axis in all gas phases (ionized, neutral atomic and molecular). We present an analysis of the multi-phase starburst driven superwind in the central 5 kpc as traced in spatially resolved spectral line observations, using far-IR Herschel PACS spectroscopy, to probe the effects on the atomic and ionized gas, and optical integral field spectroscopy to examine the ionized gas through diagnostic line ratios. We observe an increased ~250 km/s velocity dispersion in the [OI] 63 micron, [OIII] 88 micron, [NII] 122 micron and [CII] 158 micron fine-structure lines that is spatially coincident with high excitation gas above and below the disk. We model this with a slow ~200 km/s shock and trace the superwind to the edge of our field of view 2.5 kpc above the disk. We present new SOFIA 37 micron observations to explore the warm dust distribution, and detect no clear dust entrainment in the outflow. The stellar kinematics appear decoupled from the regular disk rotation seen in all gas phases, consistent with a recent merger event disrupting the system. We consider the role of the superwind in the evolution of NGC 2146 and speculate on the evolutionary future of the system. Our observations of NGC 2146 in the far-IR allow an unobscured view of the wind, crucial for tracing the superwind to the launching region at the disk center, and provide a local analog for future ALMA observations of outflows in high redshift systems.Comment: 16 pages, 13 figures, accepted for publication in Ap
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