Boundary regularity for the Poisson equation in reifenberg-flat domains

This paper is devoted to the investigation of the boundary regularity for the Poisson equation {{cc} -\Delta u = f & \text{in} \Omega u= 0 & \text{on} \partial \Omega where $f$ belongs to some $L^p(\Omega)$ and $\Omega$ is a Reifenberg-flat domain of $\mathbb R^n.$ More precisely, we prove that given an exponent $\alpha\in (0,1)$, there exists an $\varepsilon>0$ such that the solution $u$ to the previous system is locally H\"older continuous provided that $\Omega$ is $(\varepsilon,r_0)$-Reifenberg-flat. The proof is based on Alt-Caffarelli-Friedman's monotonicity formula and Morrey-Campanato theorem

Are spiral galaxies optically thin or thick?

The opacity of spiral galaxies is examined by modelling the dust and stellar content of individual galaxies. The model is applied to five late-type spiral galaxies (NGC 4013, IC 2531, UGC 1082, NGC 5529 and NGC 5907). Having analyzed a total of seven galaxies thus far, the five galaxies mentioned above plus UGC 2048 and NGC 891 presented in (Xilouris et al. 1997, 1998), we are able to draw some general conclusions, the most significant of which are: 1) The face-on central optical depth is less than one in all optical bands indicating that typical spiral galaxies like the ones that we have modelled would be completely transparent if they were to be seen face-on. 2) The dust scaleheight is about half that of the stars, which means that the dust is more concentrated near the plane of the disk. 3) The dust scalelength is about 1.4 times larger than that of the stars and the dust is more radially extended than the stars. 4) The dust mass is found to be about an order of a magnitude more than previously measured using the IRAS fluxes, indicating the existence of a cold dust component. The gas-to-dust mass ratio calculated is close to the value derived for our Galaxy. 5) The derived extinction law matches quite well the Galactic extinction law, indicating a universal dust behaviour.Comment: 13 pages. Accepted for publication in A&

Optical observations of NEA 162173 (1999 JU3) during the 2011-2012 apparition

Near-Earth asteroid 162173 (1999 JU3) is a potential target of two asteroid sample return missions, not only because of its accessibility but also because of the first C-type asteroid for exploration missions. The lightcurve-related physical properties of this object were investigated during the 2011-2012 apparition. We aim to confirm the physical parameters useful for JAXA's Hayabusa 2 mission, such as rotational period, absolute magnitude, and phase function. Our data complement previous studies that did not cover low phase angles. With optical imagers and 1-2 m class telescopes, we acquired the photometric data at different phase angles. We independently derived the rotational lightcurve and the phase curve of the asteroid. We have analyzed the lightcurve of 162173 (1999 JU3), and derived a synodic rotational period of 7.625 +/- 0.003 h, the axis ratio a/b = 1.12. The absolute magnitude H_R = 18.69 +/- 0.07 mag and the phase slope of G = -0.09 +/- 0.03 were also obtained based on the observations made during the 2011-2012 apparition.Comment: 4 pages, 3 figure

On the L_p-solvability of higher order parabolic and elliptic systems with BMO coefficients

We prove the solvability in Sobolev spaces for both divergence and non-divergence form higher order parabolic and elliptic systems in the whole space, on a half space, and on a bounded domain. The leading coefficients are assumed to be merely measurable in the time variable and have small mean oscillations with respect to the spatial variables in small balls or cylinders. For the proof, we develop a set of new techniques to produce mean oscillation estimates for systems on a half space.Comment: 44 pages, introduction revised, references expanded. To appear in Arch. Rational Mech. Ana

Veillonella rogosae sp. nov., an anaerobic, Gram-negative coccus isolated from dental plaque

Strains of a novel anaerobic, Gram-negative coccus were isolated from the supra-gingival plaque of children. Independent strains from each of six subjects were shown, at a phenotypic level and based on 16S rRNA gene sequencing, to be members of the genus Veillonella. Analysis revealed that the six strains shared 99.7 % similarity in their 16S rRNA gene sequences and 99.0 % similarity in their rpoB gene sequences. The six novel strains formed a distinct group and could be clearly separated from recognized species of the genus Veillonella of human or animal origin. The novel strains exhibited 98 and 91 % similarity to partial 16S rRNA and rpoB gene sequences of Veillonella parvula ATCC 10790T, the most closely related member of the genus. The six novel strains could be differentiated from recognized species of the genus Veillonella based on partial 16S rRNA and rpoB gene sequencing. The six novel strains are thus considered to represent a single novel species of the genus Veillonella, for which the name Veillonella rogosae sp. nov. is proposed. The type strain is CF100T (=CCUG 54233T=DSM 18960T)

Diagnosis of flood events in Brisbane (Australia) using a flood index based on daily effective precipitation

Like drought, flood events are extremely detrimental to the community [1, 2]. In the State of Queensland (Australia) the 2010–2011 Summer period saw a very significant flooding that appeared to be exacerbated by La Nina, with damages of magnitudes similar to previous flood in 1974 and mid-1950s [3]. Therefore, a plethora of flood events in this region raises serious questions about how best to address the vulnerability and costs [4]. Several studies documented particularly vulnerable geographic setting of the capital city, Brisbane. To name a few, the worst event was in January 1974 and next in 2010, which flooded most dwellings around Brisbane River catchment, severely in Toowoomba and the Lockyer Creek catchment (where 23 people had drowned). Insurers received some 56,200 claims with payouts totaling $2.55 billion, due to estimated inundations of 18,000 properties. Crucial to any flood mitigation and adaptation is the prediction of events with a good real-time monitoring system. The system should detect precisely the onset dates and corresponding water-intensive properties. A flood event is dependent on how abundant the water resources due to heavy rain are and how the water is dissipated over time. Hence a scientific method for detecting floods should be based on remaining effective precipitation on daily basis, due to heavy rain over a period of time. In this paper we applied an obje400+-ctive flood diagnostic method following an earlier pioneer study [6]. The Flood Index (FI) used in this research was initially developed by [6] based on the concept of daily Effective Precipitation (EP) proposed by [7] using the Available Water Resources Index (AWRI), and later used by [8] for analysis of water abundant seasons. The daily FI was applied to the flood region of Brisbane, the state capital of Queensland, Australia (27°30' S, 153°1' E). In order to compute the FI, the pre-processed daily rainfall data was acquired from Australian Bureau of Meteorology (http://www.bom.gov.au/climate/data-services/). Data for the period 1915–2012 were analysed. Since the FI was a standardized value comparing daily water resources for any Julian date to the yearly maximum values over climatological period, it detected flood starting date (for FI > 0) and represented adequately anomalously high precipitation that potentially triggered flood situation. The severity, intensity and durations were analysed by running sum approach of [9] over identified flood periods between onset and termination dates. Our results demonstrated good skill of the daily Flood Index for objective diagnosis and monitoring of flood events based on water intensive properties. The method allowed for the detection of the event, and quantified its properties for comparison of various events. The method was novel for quantifying floods and appears quite promising for forecasting flood events using time-series approaches