225,777 research outputs found

    Phase curves of WASP-33b and HD 149026b and a New Correlation Between Phase Curve Offset and Irradiation Temperature

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    We present new 3.6 and 4.5 μm\mu m Spitzer phase curves for the highly irradiated hot Jupiter WASP-33b and the unusually dense Saturn-mass planet HD 149026b. As part of this analysis, we develop a new variant of pixel level decorrelation that is effective at removing intrapixel sensitivity variations for long observations (>10 hours) where the position of the star can vary by a significant fraction of a pixel. Using this algorithm, we measure eclipse depths, phase amplitudes, and phase offsets for both planets at 3.6 μm\mu m and 4.5 μm\mu m. We use a simple toy model to show that WASP-33b's phase offset, albedo, and heat recirculation efficiency are largely similar to those of other hot Jupiters despite its very high irradiation. On the other hand, our fits for HD 149026b prefer a very high albedo and an unusually high recirculation efficiency. We also compare our results to predictions from general circulation models, and find that while neither are a good match to the data, the discrepancies for HD 149026b are especially large. We speculate that this may be related to its high bulk metallicity, which could lead to enhanced atmospheric opacities and the formation of reflective cloud layers in localized regions of the atmosphere. We then place these two planets in a broader context by exploring relationships between the temperatures, albedos, heat transport efficiencies, and phase offsets of all planets with published thermal phase curves. We find a striking relationship between phase offset and irradiation temperature--the former drops with increasing temperature until around 3400 K, and rises thereafter. Although some aspects of this trend are mirrored in the circulation models, there are notable differences that provide important clues for future modeling efforts

    The stellar host in star-forming low-mass galaxies: Evidence for two classes

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    The morphological evolution of star-forming galaxies provides important clues to understand their physical properties, as well as the triggering and quenching mechanisms of star formation. We aim at connecting morphology and star-formation properties of low-mass galaxies (median stellar mass ∼\sim 108.5^{8.5} M⊙_{\odot}) at low redshift (z<0.36z<0.36). We use a sample of medium-band selected star-forming galaxies from the GOODS-North field. Hα\alpha images for the sample are created combining both spectral energy distribution fits and HST data. Using them, we mask the star forming regions to obtain an unbiased two-dimensional model of the light distribution of the host galaxies. For this purpose we use PHI\texttt{PHI}, a new Bayesian photometric decomposition code. We apply it independently to 7 HST bands assuming a S\'ersic surface brightness model. Star-forming galaxy hosts show low S\'ersic index (with median nn ∼\sim 0.9), as well as small sizes (median ReR_e ∼\sim 1.6 kpc), and negligible change of the parameters with wavelength (except for the axis ratio, which grows with wavelength). Using a clustering algorithm, we find two different classes of star-forming galaxies: A more compact, redder, and high-nn (class A) and a more extended, bluer and lower-nn one (class B). We also find evidence that the first class is more spheroidal-like. In addition, we find that 48% of the analyzed galaxies present negative color gradients (only 5% are positive). The host component of low-mass star-forming galaxies at z<0.36z<0.36 separates into two different classes, similar to what has been found for their higher mass counterparts. The results are consistent with an evolution from class B to class A. Several mechanisms from the literature, like minor and major mergers, and violent disk instability, can explain the physical process behind the likely transition between the classes. [abridged]Comment: Accepted for publication in Astronomy & Astrophysics. 13 pages, 11 figure

    The European Citizens' Initiative: the territorial extension of a European political public sphere?

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    A key aim of the European Citizens' Initiative (ECI) introduced in 2012 was to promote transnational discussion and deliberation, but there is relatively little analysis of the impact of this feature. We use primary and secondary data collection to examine the legacies left by almost 50 ECI campaigns at the conclusion of their official status, identifying mixed results. Using data drawn from interviews with 22 Citizen Committees, we identify and assess ECI campaigns which have disappeared with little trace of continued networks of communication, and at the other end of the spectrum, we find a notable reach of campaigns into some Central and East European countries, in which a young cohort of post-student campaigners attracted by the use of new technologies for campaigning feature prominently. In recognition of debates about the prospects for EU democratisation which transnational contestation might provide, we identify from continuing campaigns shared features which may provide clues as to the formation of political public spheres across national boundaries

    Discovery of Protein Phosphorylation Motifs through Exploratory Data Analysis

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    BACKGROUND: The need for efficient algorithms to uncover biologically relevant phosphorylation motifs has become very important with rapid expansion of the proteomic sequence database along with a plethora of new information on phosphorylation sites. Here we present a novel unsupervised method, called Motif Finder (in short, F-Motif) for identification of phosphorylation motifs. F-Motif uses clustering of sequence information represented by numerical features that exploit the statistical information hidden in some foreground data. Furthermore, these identified motifs are then filtered to find "actual" motifs with statistically significant motif scores. RESULTS AND DISCUSSION: We have applied F-Motif to several new and existing data sets and compared its performance with two well known state-of-the-art methods. In almost all cases F-Motif could identify all statistically significant motifs extracted by the state-of-the-art methods. More importantly, in addition to this, F-Motif uncovers several novel motifs. We have demonstrated using clues from the literature that most of these new motifs discovered by F-Motif are indeed novel. We have also found some interesting phenomena. For example, for CK2 kinase, the conserved sites appear only on the right side of S. However, for CDK kinase, the adjacent site on the right of S is conserved with residue P. In addition, three different encoding methods, including a novel position contrast matrix (PCM) and the simplest binary coding, are used and the ability of F-motif to discover motifs remains quite robust with respect to encoding schemes. CONCLUSIONS: An iterative algorithm proposed here uses exploratory data analysis to discover motifs from phosphorylated data. The effectiveness of F-Motif has been demonstrated using several real data sets as well as using a synthetic data set. The method is quite general in nature and can be used to find other types of motifs also. We have also provided a server for F-Motif at http://f-motif.classcloud.org/, http://bio.classcloud.org/f-motif/ or http://ymu.classcloud.org/f-motif/

    A search for strong, ordered magnetic fields in Herbig Ae/Be stars

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    The origin of magnetic fields in intermediate-mass and high-mass stars is fundamentally a mystery. Clues toward solving this basic astrophysical problem can likely be found at the pre-main sequence (PMS) evolutionary stage. With this work, we perform the largest and most sensitive search for magnetic fields in pre-main sequence Herbig Ae/Be (HAeBe) stars. Sixty-eight observations of 50 HAeBe stars have been obtained in circularly polarised light using the FORS1 spectropolarimeter at the ESO VLT. An analysis of both Balmer and metallic lines reveals the possible presence of weak longitudinal magnetic fields in photospheric lines of two HAeBe stars, HD 101412 and BF Ori. The intensity of the longitudinal fields detected in HD 101412 and BF Ori suggest that they correspond to globally-ordered magnetic fields with surface intensities of order 1 kG. Monte Carlo simulations of the longitudinal field measurements of the undetected stars allow us to place an upper limits of about 300 G on the general presence of aligned magnetic dipole magnetic fields, and of about 500 G on perpendicular dipole fields. We find that the observed bulk incidence of magnetic HAeBe stars in our sample is 8-12%, in good agreement with that of magnetic main sequence stars of similar masses. We also find that the rms longitudinal field intensity of magnetically-detected HAeBe stars is similar to that of Ap stars and consistent with magnetic flux conservation during stellar evolution. These results are all in agreement with the hypothesis that the magnetic fields of main sequence Ap/Bp stars are fossils, which already exist within the stars at the pre-main sequence stage. Finally, we explore the ability of our new magnetic data to constrain magnetospheric accretion in Herbig Ae/Be stars.Comment: Accepted by Monthly Notices of the Royal Astronomical Society, 2007 January 11. Received 2007 January 11; in original form 2006 August 18. The paper contains 18 pages, 11 figures and 2 table

    Look and say technique in teaching vocabulary for improving students vocabulary mastery: an experimental study at the six grade students of MI AI-Mishbah Bandung

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    Selecting a technique in teaching vocabulary was necessary to increase student language ability. Look and Say technique is one of techniques that is enable to increase students' language ability in vocabulary mastery. In this technique students are taught to memorize words by sight, student learn carefully and draw on picture clues and key words, the students are encouraged to glean meaning of unfamiliar words from the context. This skill is oriented to train students to independent readers. Look and Say technique is great for providing and overview of a topic. So, students have some hooks and which they can hang the new knowledge that they might encounter during the study. This research is based on the difficulties faced by students of Elementary School in Vocabulary mastery of simples words it is important to find need and alternative way of teaching learning vocabulary to enhance students mastery of vocabulary. Therefore, I tried to apply teaching learning process by using Look and Say technique to enhance student mastery of vocabulary. I used and experiment technique that involved to students groups: experiment and control groups. The sample of research was class VI A by using Look and Say technique (experiment groups), and class VI B without using Look and Say technique (control Group), it used conventional method. In conventional English Method a the researcher used technique of direct method and the students a were given homework. This research was conducted to find out students pre-treatment ability and their post-treatment ability on mastery of vocabulary and to find out effect of picture clues on their ability in mastery on vocabulary. The instrument of research was vocabulary mastery test. The test consisted of 18 item on the mastery of vocabulary. The collecting of data were carried out by using pre-test and post-test. The data on the mastery of vocabulary test were analyzed by using t-test and descriptive analysis. The result of the data analysis showed that tc„u„t = of 15.75. t distribution table on a = of 5%, and liable of 6.6, so (count ttable In other words the null hypothesis wes rejected. Conversely. Alternative hypothesis MD was accepted. Based on the result of the average of pre-test, the students mastery of vocabulary of both experiment and control groups is so difkrent ( experiment group =74.1 and control group = 49.4). It means that the students mastery of vocabulary in experiment group was better than the students mastery of vocabulary in the control group
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