On transonic viscous-inviscid interaction

The paper is concerned with the interaction between the boundary layer on a smooth body surface and the outer inviscid compressible flow in the vicinity of a sonic point. First, a family of local self-similar solutions of the Karman-Guderley equation describing the inviscid flow behaviour immediately outside the interaction region is analysed; one of them was found to be suitable for describing the boundary-layer separation. In this solution the pressure has a singularity at the sonic point with the pressure gradient on the body surface being inversely proportional to the cubic root dp_w/dx~(−x)^{-1/3} of the distance (−x) from the sonic point. This pressure gradient causes the boundary layer to interact with the inviscid part of the flow. It is interesting that the skin friction in the boundary layer upstream of the interaction region shows a characteristic logarithmic decay which determines an unusual behaviour of the flow inside the interaction region. This region has a conventional triple-deck structure. To study the interactive flow one has to solve simultaneously the Prandtl boundary-layer equations in the lower deck which occupies a thin viscous sublayer near the body surface and the Karman-Guderley equations for the upper deck situated in the inviscid flow outside the boundary layer. In this paper a numerical solution of the interaction problem is constructed for the case when the separation region is entirely contained within the viscous sublayer and the inviscid part of the flow remains marginally supersonic. The solution proves to be non-unique, revealing a hysteresis character of the flow in the interaction region

Sizes and Kinematics of Extended Narrow-Line Regions in Luminous Obscured AGN Selected by Broadband Images

To study the impact of active galactic nuclei (AGN) feedback on the galactic ISM, we present Magellan long-slit spectroscopy of 12 luminous nearby type 2 AGN (L_bol~10^{45.0-46.5} erg/s, z~0.1). These objects are selected from a parent sample of spectroscopically identified AGN to have high [OIII]{\lambda}5007 and WISE mid-IR luminosities and extended emission in the SDSS r-band images, suggesting the presence of extended [OIII]{\lambda}5007 emission. We find spatially resolved [OIII] emission (2-35 kpc from the nucleus) in 8 out of 12 of these objects. Combined with samples of higher luminosity type 2 AGN, we confirm that the size of the narrow-line region (R_NLR) scales with the mid-IR luminosity until the relation flattens at ~10 kpc. Nine out of 12 objects in our sample have regions with broad [OIII] linewidths (w_80>600 km/s), indicating outflows. We define these regions as the kinematically-disturbed region (KDR). The size of the KDR (R_KDR) is typically smaller than R_NLR by few kpc but also correlates strongly with the AGN mid-IR luminosity. Given the unknown density in the gas, we derive a wide range in the energy efficiency {\eta}=dot{E}/L_bol=0.01%-30%. We find no evidence for an AGN luminosity threshold below which outflows are not launched. To explain the sizes, velocity profiles, and high occurrence rates of the outflows in the most luminous AGN, we propose a scenario in which energy-conserving outflows are driven by AGN episodes with ~10^8-year durations. Within each episode the AGN flickers on shorter timescales, with a cadence of ~10^6 year active phases separated by ~10^7 years.Comment: 32 pages, 21 figures, ApJ in revie

Generalized conductance sum rule in atomic break junctions

When an atomic-size break junction is mechanically stretched, the total conductance of the contact remains approximately constant over a wide range of elongations, although at the same time the transmissions of the individual channels (valence orbitals of the junction atom) undergo strong variations. We propose a microscopic explanation of this phenomenon, based on Coulomb correlation effects between electrons in valence orbitals of the junction atom. The resulting approximate conductance quantization is closely related to the Friedel sum rule.Comment: 4 pages, 1 figure, appears in Proceedings of the NATO Advanced Research Workshop ``Size dependent magnetic scattering'', Pecs, Hungary, May 28 - June 1, 200

ALMA Observations of a Candidate Molecular Outflow in an Obscured Quasar

We present Atacama Large Millimeter/Submillimeter Array (ALMA) CO (1-0) and CO (3-2) observations of SDSS J135646.10+102609.0, an obscured quasar and ultra-luminous infrared galaxy (ULIRG) with two merging nuclei and a known 20-kpc-scale ionized outflow. The total molecular gas mass is M_{mol} ~ 9^{+19}_{-6} x 10^8 Msun, mostly distributed in a compact rotating disk at the primary nucleus (M_{mol} ~ 3 x 10^8 Msun) and an extended tidal arm (M_{mol} ~ 5 x 10^8 Msun). The tidal arm is one of the most massive molecular tidal features known; we suggest that it is due to the lower chance of shock dissociation in this elliptical/disk galaxy merger. In the spatially resolved CO (3-2) data, we find a compact (r ~ 0.3 kpc) high velocity (v ~ 500 km/s) red-shifted feature in addition to the rotation at the N nucleus. We propose a molecular outflow as the most likely explanation for the high velocity gas. The outflowing mass of M_{mol} ~ 7 x 10^7 Msun and the short dynamical time of t_{dyn} ~ 0.6 Myr yield a very high outflow rate of \dot{M}_{mol} ~ 350 Msun/yr and can deplete the gas in a million years. We find a low star formation rate (< 16 Msun/yr from the molecular content and < 21 Msun/yr from the far-infrared spectral energy distribution decomposition) that is inadequate to supply the kinetic luminosity of the outflow (\dot{E} ~ 3 x 10^43 erg/s). Therefore, the active galactic nucleus, with a bolometric luminosity of 10^46 erg/s, likely powers the outflow. The momentum boost rate of the outflow (\dot{p}/(Lbol/c) ~ 3) is lower than typical molecular outflows associated with AGN, which may be related to its compactness. The molecular and ionized outflows are likely two distinct bursts induced by episodic AGN activity that varies on a time scale of 10^7 yr.Comment: 16 pages, 7 figures, ApJ accepte

Constructing solutions to the Bj\"orling problem for isothermic surfaces by structure preserving discretization

In this article, we study an analog of the Bj\"orling problem for isothermic surfaces (that are more general than minimal surfaces): given a real analytic curve $\gamma$ in ${\mathbb R}^3$, and two analytic non-vanishing orthogonal vector fields $v$ and $w$ along $\gamma$, find an isothermic surface that is tangent to $\gamma$ and that has $v$ and $w$ as principal directions of curvature. We prove that solutions to that problem can be obtained by constructing a family of discrete isothermic surfaces (in the sense of Bobenko and Pinkall) from data that is sampled along $\gamma$, and passing to the limit of vanishing mesh size. The proof relies on a rephrasing of the Gauss-Codazzi-system as analytic Cauchy problem and an in-depth-analysis of its discretization which is induced from the geometry of discrete isothermic surfaces. The discrete-to-continuous limit is carried out for the Christoffel and the Darboux transformations as well.Comment: 29 pages, some figure

Extended X-ray Emission From a Quasar-Driven Superbubble

We present observations of extended, 20-kpc scale soft X-ray gas around a luminous obscured quasar hosted by an ultra-luminous infrared galaxy caught in the midst of a major merger. The extended X-ray emission is well fit as a thermal gas with a temperature of kT ~ 280 eV and a luminosity of L_X ~ 10^42 erg/s and is spatially coincident with a known ionized gas outflow. Based on the X-ray luminosity, a factor of ~10 fainter than the [OIII] emission, we conclude that the X-ray emission is either dominated by photoionization, or by shocked emission from cloud surfaces in a hot quasar-driven wind.Comment: Accepted for publication in ApJ, 6 pages, 2 figure

MRSA eradication of newly acquired lower respiratory tract infection in cystic fibrosis

UK cystic fibrosis (CF) guidelines recommend eradication of methicillin-resistant Staphylococcus aureus (MRSA) when cultured from respiratory samples. As there is no clear consensus as to which eradication regimen is most effective, we determined the efficacy of eradication regimens used in our CF centre and long-term clinical outcome. All new MRSA positive sputum cultures (n=37) that occurred between 2000 and 2014 were reviewed. Eradication regimen characteristics and clinical, microbiological and long-term outcome data were collected. Rifampicin plus fusidic acid was the most frequently used regimen (24 (65%) out of 37 patients), with an overall success rate of 79% (19 out of 24 patients). Eradication failure was more likely in patients with an additional MRSA-positive peripheral screening swab (p=0.03) and was associated with worse survival (p=0.04). Our results demonstrate the feasibility and clinical benefits of MRSA eradication. As peripheral colonisation was associated with lower eradication success, strategies combining systemic and topical treatments should be considered to optimise outcomes in CF patients

Peningkatan Produktivitas Tanah Melalui Sistem Agroforestri

. The low soil fertility and high toxic elements caused by high rainfall (&gt;2,500 mm/year) is the main factor responsible for the low soil productivity in the humid tropical zone, like Indonesia. In this condition, agroforestry system is expected to be solution. There are three components of agroforestry: silviculture, agriculture and livestock. Agroforestry in Indonesian is called Wanatani that means planting trees in agricultural land. Trees have deep rooting and spread intensively in subsoil may reduce leaching nutrient both vertically and horizontally. Cover crop protected soil from erosion. This role makes agroforestry as one form of soil and water conservation practices, produced some products that have a high economic value. This situation allowed agroforestry as a system of sustainable land management

Refining the M_BH-V_c scaling relation with HI rotation curves of water megamaser galaxies

Black hole - galaxy scaling relations provide information about the coevolution of supermassive black holes and their host galaxies. We compare the black hole mass - circular velocity (MBH - Vc) relation with the black hole mass - bulge stellar velocity dispersion (MBH - sigma) relation, to see whether the scaling relations can passively emerge from a large number of mergers, or require a physical mechanism, such as feedback from an active nucleus. We present VLA H I observations of five galaxies, including three water megamaser galaxies, to measure the circular velocity. Using twenty-two galaxies with dynamical MBH measurements and Vc measurements extending to large radius, our best-fit MBH - Vc relation, log MBH = alpha + beta log(Vc /200 km s^-1), yields alpha = 7.43+/-0.13, beta = 3.68+1.23/-1.20, and intrinsic scatter epsilon_int = 0.51+0.11/-0.09. The intrinsic scatter may well be higher than 0.51, as we take great care to ascribe conservatively large observational errors. We find comparable scatter in the MBH - sigma relations, epsilon_int = 0.48+0.10/-0.08, while pure merging scenarios would likely result in a tighter scaling with the dark halo (as traced by Vc) than baryonic (sigma) properties. Instead, feedback from the active nucleus may act on bulge scales to tighten the MBH - sigma relation with respect to the MBH - Vc relation, as observed.Comment: 27 pages, 15 figures, ApJ accepte

Sensitive Chemical Compass Assisted by Quantum Criticality

The radical-pair-based chemical reaction could be used by birds for the navigation via the geomagnetic direction. An inherent physical mechanism is that the quantum coherent transition from a singlet state to triplet states of the radical pair could response to the weak magnetic field and be sensitive to the direction of such a field and then results in different photopigments in the avian eyes to be sensed. Here, we propose a quantum bionic setup for the ultra-sensitive probe of a weak magnetic field based on the quantum phase transition of the environments of the two electrons in the radical pair. We prove that the yield of the chemical products via the recombination from the singlet state is determined by the Loschmidt echo of the environments with interacting nuclear spins. Thus quantum criticality of environments could enhance the sensitivity of the detection of the weak magnetic field.Comment: 4 pages, 3 figure