791 research outputs found

    THE INTERLANGUAGE DEVELOPMENT OF ARTICLES IN ENGLISH AS A SECOND LANGUAGE: A LONGITUDINAL STUDY

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    Speakers of other languages often have trouble learning the article system in English. This study traces the development of six learners, three Arabic speakers whose first language (L1) has articles and three Chinese speakers whose L1 does not. The study follows how learners use articles and maps that usage onto Huebner's (1983) semantic wheel to see their interlanguage form-function relationships with articles. Short spontaneous speeches by two groups of learners over the course of a year were used to see if the learners' L1 affects their development (Master, 1997; Zobl, 1982). Articles are examined in the context of the noun phrase in which they appear (Liu & Gleason, 2002; Huebner, 1983; Parrish, 1987; Robertson, 2000) and the countability of the noun phrase is also considered (Hiki, 1990). It was found that the Arabic speakers were more accurate in their use of the and š, but the Chinese were more accurate with a(n). Overall, there are few differences between the target-like use of the two groups and this is hypothesized to be due to neither Arabic nor Chinese having an indefinite article (Kharma, 1981; Thompson-Panos & Thomas-RuĂŸiĂŁ, 1983; Roberston, 2000). However, because Arabic has a definite article while Chinese does not, the Arabic speakers seem to develop a more target-like representation of the earlier than the Chinese speakers. The Chinese speakers confirmed acquisition stages proposed by Thomas (1989), while the Arabic speakers seem to associate a in introductory contexts (I had a friend named Tom) before existential contexts (That is a truck) and this is hypothesized to be a result of L1 transfer. This study concludes by illustrating the development using Huebner's semantic wheel to map out both groups' form-function relationships over time (Butler, 2002; Huebner, 1983) and suggesting that the article acquisition stages proposed are not as universal as previously thought (Master, 1995; Thomas, 1989), but actually differ based on features in the learner's L1

    Ad- and desorption of Rb atoms on a gold nanofilm measured by surface plasmon polaritons

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    Hybrid quantum systems made of cold atoms near nanostructured surfaces are expected to open up new opportunities for the construction of quantum sensors and for quantum information. For the design of such tailored quantum systems the interaction of alkali atoms with dielectric and metallic surfaces is crucial and required to be understood in detail. Here, we present real-time measurements of the adsorption and desorption of Rubidium atoms on gold nanofilms. Surface plasmon polaritons (SPP) are excited at the gold surface and detected in a phase sensitive way. From the temporal change of the SPP phase the Rubidium coverage of the gold film is deduced with a sensitivity of better than 0.3 % of a monolayer. By comparing the experimental data with a Langmuir type adsorption model we obtain the thermal desorption rate and the sticking probability. In addition, also laser-induced desorption is observed and quantified.Comment: 9 pages, 6 figure

    Surface Plankton Protozoa from Lake Erie in the Put-in-Bay Region

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    Author Institution: Department of Zoology, Clemson Colleg

    Cooperative Scattering by Cold Atoms

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    We have studied the interplay between disorder and cooperative scattering for single scattering limit in the presence of a driving laser. Analytical results have been derived and we have observed cooperative scattering effects in a variety of experiments, ranging from thermal atoms in an optical dipole trap, atoms released from a dark MOT and atoms in a BEC, consistent with our theoretical predictions.Comment: submitted for special issue of PQE 201

    Young stellar object jet models: From theory to synthetic observations

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    Astronomical observations, analytical solutions and numerical simulations have provided the building blocks to formulate the current theory of young stellar object jets. Although each approach has made great progress independently, it is only during the last decade that significant efforts are being made to bring the separate pieces together. Building on previous work that combined analytical solutions and numerical simulations, we apply a sophisticated cooling function to incorporate optically thin energy losses in the dynamics. On the one hand, this allows a self-consistent treatment of the jet evolution and on the other, it provides the necessary data to generate synthetic emission maps. Firstly, analytical disk and stellar outflow solutions are properly combined to initialize numerical two-component jet models inside the computational box. Secondly, magneto-hydrodynamical simulations are performed in 2.5D, following properly the ionization and recombination of a maximum of 2929 ions. Finally, the outputs are post-processed to produce artificial observational data. The first two-component jet simulations, based on analytical models, that include ionization and optically thin radiation losses demonstrate promising results for modeling specific young stellar object outflows. The generation of synthetic emission maps provides the link to observations, as well as the necessary feedback for the further improvement of the available models.Comment: accepted for publication A&A, 20 pages, 11 figure

    Spiral shocks in the accretion disc of IP Peg during outburst maximum

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    In response to our recent discovery of spiral arms in the accretion disc of IP Peg during rise to outburst, we have obtained time-resolved spectrophotometry of IP Peg during outburst maximum. In particular, indirect imaging of HeII 4686, using Doppler tomography, shows a two-arm spiral pattern on the disc image, which confirms repeatability over different outbursts. The jump in HeII intensity (a factor of more than two) and in velocity (~200--300 km/s) clarifies the shock nature of the spiral structure. The HeII shocks show an azimuthal extent of ~90 degrees, a shallow power-law emissivity ~V^{-1}, an upper limit of 30 degrees in opening angle, and a flux contribution of 15 per cent of the total disc emission. We discuss the results in view of recent simulations of accretion discs which show that spiral shocks can be raised in the accretion disc by the secondary star.Comment: 5 pages, 4 figures, MNRAS journal paper. in pres

    Formation of Episodic Magnetically Driven Radiatively Cooled Plasma Jets in the Laboratory

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    We report on experiments in which magnetically driven radiatively cooled plasma jets were produced by a 1 MA, 250 ns current pulse on the MAGPIE pulsed power facility. The jets were driven by the pressure of a toroidal magnetic field in a ''magnetic tower'' jet configuration. This scenario is characterized by the formation of a magnetically collimated plasma jet on the axis of a magnetic ''bubble'', confined by the ambient medium. The use of a radial metallic foil instead of the radial wire arrays employed in our previous work allows for the generation of episodic magnetic tower outflows which emerge periodically on timescales of ~30 ns. The subsequent magnetic bubbles propagate with velocities reaching ~300 km/s and interact with previous eruptions leading to the formation of shocks.Comment: 6 pages, 5 figures. Accepted for publication in Astrophysics & Space Scienc

    The channel-activating protease CAP1/Prss8 is required for placental labyrinth maturation.

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    The serine protease CAP1/Prss8 is crucial for skin barrier function, lung alveolar fluid clearance and has been unveiled as diagnostic marker for specific cancer types. Here, we show that a constitutive knockout of CAP1/Prss8 leads to embryonic lethality. These embryos presented no specific defects, but it is during this period, and in particular at E13.5, that wildtype placentas show an increased expression of CAP1/Prss8, thus suggesting a placental defect in the knockout situation. The placentas of knockout embryos exhibited significantly reduced vascular development and incomplete cellular maturation. In contrary, epiblast-specific deletion of CAP1/Prss8 allowed development until birth. These CAP1/Prss8-deficient newborns presented abnormal epidermis, and died soon after birth due to impaired skin function. We thus conclude that a late placental insufficiency might be the primary cause of embryonic lethality in CAP1/Prss8 knockouts. This study highlights a novel and crucial role for CAP1/Prss8 in placental development and function

    Effect of a conventional energy-restricted modified diet with or without meal replacement on weight loss and cardiometabolic risk profile in overweight women

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    <p>Abstract</p> <p>Background</p> <p>Abdominal obesity, atherogenic dyslipidemia and hypertension are essential risk factors for cardiovascular diseases. Several studies showed favorable effects of weight loss in overweight subjects on cardiometabolic risk profile.</p> <p>Methods</p> <p>This open-label, randomized, controlled study investigated the effect of an energy-restricted modified diet with (MR) or without meal replacements for weight control (C) on weight loss, body composition and cardiometabolic risk profile in overweight women. Of 105 randomized participants, 87 were eligible for per protocol analysis. Anthropometric, clinical, blood, 24 h-urine parameters and dietary intake were assessed at baseline and after 12 weeks.</p> <p>Results</p> <p>Dietary intervention resulted in a significant weight loss in both groups (MR: -5.98 ± 2.82 kg; p < 0.001, C: -4.84 ± 3.54 kg; p < 0.001). However, the rate of responder (weight loss >5%) was higher in MR (77%) versus C group (50%) (p = 0.010). A significant reduction in waist circumference (WC) and body fat mass (BFM) was observed in both groups. Body cell mass (BCM) and lean body mass (LBM) decreased, while percentage of BCM of body weight increased in MR more than in C group. Systolic and diastolic blood pressure (BP) significantly decreased and to a similar extent in both groups. Total cholesterol (TC), LDL-C but also HDL-C declined significantly in both groups, while no change occurred in triglycerides.</p> <p>Conclusions</p> <p>Both dietary intervention strategies had a similar effect on weight loss and body fat distribution, but rate of responder was significantly higher in MR group. Systolic BP decreased to a similar extent in both groups. Cardiometabolic risk profile improved only partly in both groups.</p
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