50,723 research outputs found

    Metallicities of galaxies in the nearby Lynx-Cancer void

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    Does the void environment have a sizable effect on the evolution of dwarf galaxies? If yes, the best probes should be the most fragile least massive dwarfs. We compiled a sample of about one hundred dwarfs with M_B in the range -12 to -18 mag, falling within the nearby Lynx-Cancer void. The goal is to study their evolutionary parameters -- gas metallicity and gas mass-fraction, and to address the epoch of the first substantial episode of Star Formation. Here we present and discuss the results of O/H measurements in 38 void galaxies, among which several the most metal-poor galaxies are found with the oxygen abundances of 12+log(O/H)=7.12-7.3 dex.Comment: 2 pages, one figure. To appear in proceedings of 'Environment and the Formation of Galaxies: 30 years later,' (Lisbon, September 2010), published by Springer-Verla

    A slow coronal mass ejection with rising X-ray source

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    An eruptive event, which occurred on 16th April 2002, is discussed. Using images from the Transition Region and Coronal Explorer ( TRACE) at 195 angstrom, we observe a lifting flux rope which gives rise to a slow coronal mass ejection ( CME). There are supporting velocity observations from the Coronal Diagnostic Spectrometer ( CDS) on the Solar and Heliospheric Observatory ( SOHO), which illustrate the helical nature of the structure. Additionally a rising coronal hard X- ray source, which is observed with the Reuven Ramaty High Energy Solar Spectroscopic Imager ( RHESSI), is shown to follow the flux rope with a speed of similar to 60 km s(-1). It is also sampled by the CDS slit, although it has no signature in the Fe XIX band. Following the passage of this source, there is evidence from the CDS for down- flowing ( cooling) material along newly reconnected loops through Doppler velocity observations, combined with magnetic field modeling. Later, a slow CME is observed with the Large Angle and Spectroscopic Coronagraph ( LASCO). We combine a height- time profile of the flux rope at lower altitudes with the slow CME. The rising flux rope speeds up by a factor of 1.7 at the start of the impulsive energy release and goes through further acceleration before reaching 1.5 solar radii. These observations support classical CME scenarios in which the eruption of a filament precedes flaring activity. Cusped flare loops are observed following the erupting flux rope and their altitude increases with time. In addition we find RHESSI sources both below and above the probable location of the reconnection region

    Guidelines for the design of haptic widgets

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    Haptic feedback has been shown to improve user performance in Graphical User Interface (GUI) targeting tasks in a number of studies. These studies have typically focused on interactions with individual targets, and it is unclear whether the performance increases reported will generalise to the more realistic situation where multiple targets are presented simultaneously. This paper addresses this issue in two ways. Firstly two empirical studies dealing with groups of haptically augmented widgets are presented. These reveal that haptic augmentations of complex widgets can reduce performance, although carefully designed feedback can result in performance improvements. The results of these studies are then used in conjunction with the previous literature to generate general design guidelines for the creation of haptic widgets

    Energy and centrality dependences of charged multiplicity density in relativistic nuclear collisions

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    Using a hadron and string cascade model, JPCIAE, the energy and centrality dependences of charged particle pseudorapidity density in relativistic nuclear collisions were studied. Within the framework of this model, both the relativistic p+pˉp+\bar p experimental data and the PHOBOS and PHENIX Au+AuAu+Au data at snn\sqrt s_{nn}=130 GeV could be reproduced fairly well without retuning the model parameters. The predictions for full RHIC energy Au+AuAu+Au collisions and for Pb+PbPb+Pb collisions at the ALICE energy were given. Participant nucleon distributions were calculated based on different methods. It was found that the number of participant nucleons, ,isnotawelldefinedvariablebothexperimentallyandtheoretically.Therefore,itisinappropriatetousechargedparticlepseudorapiditydensityperparticipantpairasafunctionof, is not a well defined variable both experimentally and theoretically. Therefore, it is inappropriate to use charged particle pseudorapidity density per participant pair as a function of for distinguishing various theoretical models.Comment: 10 pages, 4 figures, submitted to Phy. Lett.

    Estrogen Binding Protein Activity in Morris Hepatoma 7777 Compared With Normal Rat Liver

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    Estrogen binding protein activities were determined in the cytosol from adult male Buffalo rat liver and Morris hepatoma 7777. Estrogen receptors were prepared using the protamine sulfate precipitation technique of Chamness. The ability of various unlabeled steroids competing with [3H]estradiol was examined to establish the binding specificity. Estradiol binding in Morris hepatoma 7777 cytosol was greatly decreased compared with that present in hepatic cytosol prepared from normal rat liver. The receptor concentration expressed as femtomoles per milligram of cytoplasmic protein was 31.1 ± 2.9 SD for normal rat liver and 0.41 ± 0.88 SD for the hepatoma. Gel filtration chromatography revealed the presence of an estrogen binder in hepatoma cytosol which was not present in either normal liver or in the protamine sulfate precipitates of hepatoma cytosol. The molecular weight, binding specificity, and precipitation of this protein by specific antiserum suggests that it is α-fetoprotein. © 1984, American Gastroenterological Association. All rights reserved

    Local three-nucleon interaction from chiral effective field theory

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    The three-nucleon (NNN) interaction derived within the chiral effective field theory at the next-to-next-to-leading order (N2LO) is regulated with a function depending on the magnitude of the momentum transfer. The regulated NNN interaction is then local in the coordinate space, which is advantages for some many-body techniques. Matrix elements of the local chiral NNN interaction are evaluated in a three-nucleon basis. Using the ab initio no-core shell model (NCSM) the NNN matrix elements are employed in 3H and 4He bound-state calculations.Comment: 17 pages, 9 figure

    Discovery of the potential role of sensors in a personal emergency response system: what can we learn from a single workshop?

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    Capturing knowledge from domain experts is important to effectively integrate novel technological support in existing care processes. In this paper, we present our experiences in using a specific type of workshop, which we identified as a decision-tree workshop, to determine the process and information exchange during the usage of a Personal Emergency Response System (PERS). We conducted the workshop with current and possible future users of a PERS system to investigate the potential of context-and social awareness for such a system. We discuss the workshop format as well as the results and reflection on this workshop

    Relating near-Earth observations of an interplanetary coronal mass ejection to the conditions at its site of origin in the solar corona

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    A halo coronal mass ejection (CME) was detected on January 20, 2004. We use solar remote sensing data (SOHO, Culgoora) and near-Earth in situ data (Cluster) to identify the CME source event and show that it was a long duration flare in which a magnetic flux rope was ejected, carrying overlying coronal arcade material along with it. We demonstrate that signatures of both the arcade material and the flux rope material are clearly identifiable in the Cluster and ACE data, indicating that the magnetic field orientations changed little as the material traveled to the Earth, and that the methods we used to infer coronal magnetic field configurations are effective
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