An Eulerian finite element method for tangential Navier-Stokes equations on evolving surfaces

The paper introduces a geometrically unfitted finite element method for the numerical solution of the tangential Navier--Stokes equations posed on a passively evolving smooth closed surface embedded in $\mathbb{R}^3$. The discrete formulation employs finite difference and finite elements methods to handle evolution in time and variation in space, respectively. A complete numerical analysis of the method is presented, including stability, optimal order convergence, and quantification of the geometric errors. Results of numerical experiments are also provided

The Dependence of the Soft X-ray Properties of LMXBs on the Metallicity of Their Environment

We determine the X-ray spectral properties of a sample of low-mass X-ray binaries (LMXBs) which reside in globular clusters of M31, as well as five LMXBs in Galactic globular clusters and in the Large Magellanic Cloud using the ROSAT PSPC. We find a trend in the X-ray properties of the LMXBs as a function of globular cluster metallicity. The spectra of LMXBs become progressively softer as the metallicity of its environment increases. The one M31 globular cluster LMXB in our sample which has a metallicity greater than solar has spectral properties similar to those of LMXBs in the bulge of M31, but markedly different from those which reside in low metallicity globular clusters, both in M31 and the Galaxy. The spectral properties of this high metallicity LMXB is also similar to those of X-ray faint early-type galaxies. This lends support to the claim that a majority of the X-ray emission from these X-ray faint early-type galaxies results from LMXBs and not hot gas, as is the case in their X-ray bright counterparts.Comment: 5 pages, 2 embedded Postscript figures, uses emulateapj.sty, Astrophysical Journal Letters, in pres

The Distance of the First Overtone RR Lyrae Variables in the MACHO LMC Database: A New Method to Correct for the Effects of Crowding

Previous studies have indicated that many of the RR Lyrae variables in the LMC have properties similar to the ones in the Galactic globular cluster M3. Assuming that the M3 RR Lyrae variables follow the same relationships among period, temperature, amplitude and Fourier phase parameter phi31 as their LMC counterparts, we have used the M3 phi31-logP relation to identify the M3-like unevolved first overtone RR Lyrae variables in 16 fields near the LMC bar. The temperatures of these variables were calculated from the M3 logP-logTe relation so that the extinction could be derived for each star separately. Since blended stars have lower amplitudes for a given period, the period amplitude relation should be a useful tool for identifying which stars are affected by crowding. We find that the low amplitude stars are brighter. We remove them from the sample and derive an LMC distance modulus 18.49+/-0.11.Comment: 30 pages, 7 figures, accepted for publication in the Astronomical Journa

Towards interoperability of entity-based and event-based IoT platforms: The case of NGSI and EPCIS standards

With the advancement of IoT devices and thanks to the unprecedented visibility and transparency they provide, diverse IoT-based applications are being developed. With the proliferation of IoT, both the amount and type of data items captured have increased dramatically. The data generated by IoT devices reside in different organizations and systems, and a major barrier to utilizing the data is the lack of interoperability among the standards used to capture the data. To reduce this barrier, two major standards have emerged: the Global Standards One (GS1) Electronic Product Code Information Service (EPCIS) and the FIWARE Next Generation Services Interface (NGSI). However, the two standards differ not only in the data encoding but also in the underlying philosophy of representing IoT data; namely, EPCIS is event-based, and NGSI is entity-based. Interoperability between FIWARE and EPCIS is essential for system integration. This paper presents OLIOT Mediation Gateway, now one of the incubated generic enablers offered by the FIWARE Foundation, that realizes the required interoperability between NGSI and EPCIS systems. It also demonstrates the applicability and feasibility of the Gateway by applying it to a real-life case study of integrating transparency systems used in a meat supply chain

A Reanalysis of theUltraviolet Extinction from Interstellar Dust in the Large Magellanic Cloud

We have reanalyzed the Large Magellanic Cloud's (LMC) ultraviolet (UV) extinction using data from the IUE final archive. Our new analysis takes advantage of the improved signal--to--noise of the IUE NEWSIPS reduction, the exclusion of stars with very low reddening, the careful selection of well matched comparison stars, and an analysis of the effects of Galactic foreground dust. Differences between the average extinction curves of the 30 Dor region and the rest of the LMC are reduced compared to previous studies. We find that there is a group of stars with very weak 2175 Ang. bumps that lie in or near the region occupied by the supergiant shell, LMC 2, on the southeast side of 30 Dor. The average extinction curves inside and outside LMC 2 show a very significant difference in 2175 Ang. bump strength, but their far--UV extinctions are similar. While it is unclear whether or not the extinction outside the LMC 2 region can be fit with the relation of Cardelli, Clayton and Mathis (CCM), sightlines near LMC 2 cannot be fit with CCM due to their weak 2175 Ang. bumps. While the extinction properties seen in the LMC lie within the range of properties seen in the Galaxy, the correlations of UV extinction properties with environment seen in the Galaxy do not appear to hold in the LMC.Comment: 29 pages, 10 figures, to be published in Ap

Presentation of Primary Open Angle Glaucoma (POAG) at Lions Sight First Eye Hospital in Blantyre, Malawi

ObjectivePrimary open angle glaucoma (POAG) is the most common type of glaucoma in Africa. We carried out a study to  determine the clinical presentation pattern of patients with primary open angle glaucoma (POAG) at a tertiary  hospital in Malawi.DesignA cross-sectional studySettingLions Sight First Eye Hospital—a major referral and teaching state eye hospital in Blantyre, MalawiSubjectsStudy participants were newly diagnosed POAG patients at specialist eye clinic during study period.ResultsA total of 60 POAG patients were recruited into the study. The mean age was 58.7 years (SD= 16.6, range 18 - 86). There were more male (44, 73.3%) than female (16, 27.7%) patients. The majority of patients (73%) presented  one year after onset of visual symptoms. Twenty-six patients (43%) had unilateral blindness (visual acuity < 3/60; WHO classification), while nine patients (15%) presented with bilateral blindness. A vertical cup-to-disc ratio (CDR) of 0.8 or worse was seen in 92 eyes (79%). The mean intraocular pressure (IOP) reading was 35.5 mmHg (SD 13.30). Of the thirty-three eyes that successfully underwent visual field analysis, very advanced defects were recorded in 12 eyes (36%).ConclusionThis study demonstrates delayed presentation and male predominance among POAG patients at a tertiary eye hospital in Malawi. Glaucoma intervention programmes should aim at identifying patients with treatable glaucoma with particular attention to women

Anchoring Knowledge in Interaction: Towards a Harmonic Subsymbolic/Symbolic Framework and Architecture of Computational Cognition

We outline a proposal for a research program leading to a new paradigm, architectural framework, and prototypical implementation, for the cognitively inspired anchoring of an agent’s learning, knowledge formation, and higher reasoning abilities in real-world interactions: Learning through interaction in real-time in a real environment triggers the incremental accumulation and repair of knowledge that leads to the formation of theories at a higher level of abstraction. The transformations at this higher level filter down and inform the learning process as part of a permanent cycle of learning through experience, higher-order deliberation, theory formation and revision. The envisioned framework will provide a precise computational theory, algorithmic descriptions, and an implementation in cyber-physical systems, addressing the lifting of action patterns from the subsymbolic to the symbolic knowledge level, effective methods for theory formation, adaptation, and evolution, the anchoring of knowledge-level objects, real-world interactions and manipulations, and the realization and evaluation of such a system in different scenarios. The expected results can provide new foundations for future agent architectures, multi-agent systems, robotics, and cognitive systems, and can facilitate a deeper understanding of the development and interaction in human-technological settings

Low-Mass Pre-Main Sequence Stars in the Large Magellanic Cloud - III: Accretion Rates from HST-WFPC2 Observations

We have measured the present accretion rate of roughly 800 low-mass (~1-1.4 Mo) pre-Main Sequence stars in the field of Supernova 1987A in the Large Magellanic Cloud (LMC, Z~0.3 Zo). It is the first time that this fundamental parameter for star formation is determined for low-mass stars outside our Galaxy. The Balmer continuum emission used to derive the accretion rate positively correlates with the Halpha excess. Both these phenomena are believed to originate from accretion from a circumstellar disk so that their simultaneous detection provides an important confirmation of the pre-Main Sequence nature of the Halpha and UV excess objects, which are likely to be the LMC equivalent of Galactic Classical TTauri stars. The stars with statistically significant excesses are measured to have accretion rates larger than 1.5x10^{-8}Mo/yr at an age of 12-16 Myrs. For comparison, the time scale for disk dissipation observed in the Galaxy is of the order of 6 Myrs. Moreover, the oldest Classical TTauri star known in the Milky Way (TW Hydrae, with 10 Myrs of age) has a measured accretion rate of only 5x10^{-10} Mo/yr, ie 30 times less than what we measure for stars at a comparable age in the LMC. Our findings indicate that metallicity plays a major role in regulating the formation of low-mass stars.Comment: Accepted for publication in the Astrophysical Journal (10 June 2004), 28 pages, 9 figures. Typo corrected in the abstract on 21 February 200

Performance of the AMS-02 Transition Radiation Detector

For cosmic particle spectroscopy on the International Space Station the AMS experiment will be equipped with a Transition Radiation Detector (TRD) to improve particle identification. The TRD has 20 layers of fleece radiator with Xe/CO2 proportional mode straw tube chambers. They are supported in a conically shaped octagon structure made of CFC-Al-honeycomb. For low power consumption VA analog multiplexers are used as front-end readout. A 20 layer prototype built from final design components has achieved proton rejections from 100 to 2000 at 90% electron efficiency for proton beam energies up to 250 GeV with cluster counting, likelihood and neural net selection algorithms.Comment: 11 pages, 25 figures, espcrc2.sty (elsevier 2-column