2,598 research outputs found
Parental cultural models and resources for understanding mathematical achievement in culturally diverse school settings
This paper proposes that the theoretical concept of cultural models can offer useful insights into parental involvement in their child’s mathematical achievement and the resources they use to go about gaining information in culturally diverse learning settings. This examination takes place within a cultural-developmental framework and draws on the notion of cultural models to explicate parental understandings of their child’s mathematics achievement and what resources are used to make sense of this. Three parental resources are scrutinized: (a) the teacher, (b) examination test results, and (c) constructions of child development. The interviews with 22 parents revealed some ambiguity around the interpretation of these resources by the parent, which was often the result of incongruent cultural models held between the home and the school. The resources mentioned are often perceived as being unambiguous but show themselves instead to be highly interpretive because of the diversity of cultural models in existence in culturally diverse settings. Parents who are in minority or marginalized positions tend to have difficulties in interpreting cultural models held by school, thereby disempowering them to be parentally involved in the way the school would like
New GTC spectroscopic data and a statistical study to better constrain the redshift of the BL Lac RGB J2243 + 203
We present new spectroscopic data of the BL Lac RGB 2243 + 203, and its surroundings, obtained with the OSIRIS Multi Object Spectrograph (MOS) mounted in the Gran Telescopio Canarias (GTC). The spectra of neither the BL Lac nor its host galaxy show any spectral feature, thus hindering direct determination of its redshift. The spectroscopic redshift distribution of objects in the MOS field of view shows four galaxies with redshift between 0.5258 and 0.5288. We make use of a statistical analysis to test the possibility that the targeted BL Lac may be a member of that group. By using the spectroscopic redshifts obtained with our GTC observations, we found that this probability is between 86 and 93 per cent.Fil: Rosa González, D. Instituto Nacional de Astrofísica, Optica y Electrónica; MéxicoFil: Muriel, Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Mayya, Y. D.. Instituto Nacional de Astrofísica, Optica y Electrónica; MéxicoFil: Aretxaga, I.. Instituto Nacional de Astrofísica, Optica y Electrónica; MéxicoFil: Becerra González, J.. Instituto de Astrofisica de Canarias; EspañaFil: Carramiñana, Alberto. Instituto Nacional de Astrofísica, Optica y Electrónica; MéxicoFil: Méndez-Abreu, J.. Instituto Nacional de Astrofísica, Optica y Electrónica; MéxicoFil: Vega, O. Instituto Nacional de Astrofísica, Optica y Electrónica; MéxicoFil: Terlevich, E-. Instituto Nacional de Astrofísica, Optica y Electrónica; MéxicoFil: Coutiño de León, S.. Instituto Nacional de Astrofísica, Optica y Electrónica; MéxicoFil: Furniss, A.. Instituto Nacional de Astrofísica, Optica y Electrónica; MéxicoFil: Longinotti, A. L.. Instituto Nacional de Astrofísica, Optica y Electrónica; MéxicoFil: Terlevich, R. J.. Instituto Nacional de Astrofísica, Optica y Electrónica; MéxicoFil: Pichel, Ana Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Rovero, Adrian Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Donzelli, Carlos Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; Argentin
Wavelength calibration for OSIRIS/GTC* tunable filters
OSIRIS (Optical System for Imaging and low Resolution Integrated
Spectroscopy) is the first light instrument of the Gran Telescopio Canarias
(GTC). It provides a flexible and competitive tunable filter (TF). Since it is
based on a Fabry-Perot interferometer working in collimated beam, the TF
transmission wavelength depends on the position of the target with respect to
the optical axis. This effect is non-negligible and must be accounted for in
the data reduction. Our paper establishes a wavelength calibration for OSIRIS
TF with the accuracy required for spectrophotometric measurements using the
full field of view (FOV) of the instrument. The variation of the transmission
wavelength across the FOV is well described by
, where is the central
wavelength, represents the physical distance from the optical axis, and
mm is the effective focal length of the camera lens. This
new empirical calibration yields an accuracy better than 1\,\AA\ across the
entire OSIRIS FOV (8\arcmin8\arcmin), provided that the position
of the optical axis is known within 45 m ( 1.5 binned pixels). We
suggest a calibration protocol to grant such precision over long periods, upon
re-alignment of OSIRIS optics, and in different wavelength ranges. This
calibration differs from the calibration in OSIRIS manual which, nonetheless,
provides an accuracy \AA\, for R\lesssim 2\arcmin.Comment: 22 pages, 7 figures, accepted for publication in PAS
The intrinsic shape of galaxy bulges
The knowledge of the intrinsic three-dimensional (3D) structure of galaxy
components provides crucial information about the physical processes driving
their formation and evolution. In this paper I discuss the main developments
and results in the quest to better understand the 3D shape of galaxy bulges. I
start by establishing the basic geometrical description of the problem. Our
understanding of the intrinsic shape of elliptical galaxies and galaxy discs is
then presented in a historical context, in order to place the role that the 3D
structure of bulges play in the broader picture of galaxy evolution. Our
current view on the 3D shape of the Milky Way bulge and future prospects in the
field are also depicted.Comment: Invited Review to appear in "Galactic Bulges" Editors: Laurikainen
E., Peletier R., Gadotti D. Springer Publishing. 24 pages, 7 figure
Search for Top Squark Pair Production in the Dielectron Channel
This report describes the first search for top squark pair production in the
channel stop_1 stopbar_1 -> b bbar chargino_1 chargino_1 -> ee+jets+MEt using
74.9 +- 8.9 pb^-1 of data collected using the D0 detector. A 95% confidence
level upper limit on sigma*B is presented. The limit is above the theoretical
expectation for sigma*B for this process, but does show the sensitivity of the
current D0 data set to a particular topology for new physics.Comment: Five pages, including three figures, submitted to PRD Brief Report
Arm and interarm abundance gradients in CALIFA spiral galaxies
Spiral arms are the most singular features in disc galaxies. These structures can exhibit different patterns, namely grand design and flocculent arms, with easily distinguishable characteristics. However, their origin and the mechanisms shaping them are unclear. The overall role of spirals in the chemical evolution of disc galaxies is another unsolved question. In particular, it has not been fully explored if the H ii regions of spiral arms present different properties from those located in the interarm regions. Here we analyse the radial oxygen abundance gradient of the arm and interarm star forming regions of 63 face-on spiral galaxies using CALIFA Integral Field Spectroscopy data. We focus the analysis on three characteristic parameters of the profile: slope, zero-point, and scatter. The sample is morphologically separated into flocculent versus grand design spirals and barred versus unbarred galaxies. We find subtle but statistically significant differences betweenthe arm and interarm distributions for flocculent galaxies, suggesting that the mechanisms generating the spiral structure in these galaxies may be different to those producing grand design systems, for which no significant differences are found. We also find small differences in barred galaxies, not observed in unbarred systems, hinting that bars may affect the chemical distribution of these galaxies but not strongly enough as to be reflected in the overall abundance distribution. In light of these results, we propose bars and flocculent structure as two distinct mechanisms inducing differences in the abundance distribution between arm and interarm star forming regions
Search for Production via Trilepton Final States in collisions at TeV
We have searched for associated production of the lightest chargino,
, and next-to-lightest neutralino, , of the
Minimal Supersymmetric Standard Model in collisions at
\mbox{ = 1.8 TeV} using the \D0 detector at the Fermilab Tevatron
collider. Data corresponding to an integrated luminosity of 12.5 \ipb
were examined for events containing three isolated leptons. No evidence for
pair production was found. Limits on
BrBr are
presented.Comment: 17 pages (13 + 1 page table + 3 pages figures). 3 PostScript figures
will follow in a UUEncoded, gzip'd, tar file. Text in LaTex format. Submitted
to Physical Review Letters. Replace comments - Had to resumbmit version with
EPSF directive
Search for bottom squarks in pbarp collisions at sqrt(s)=1.8 TeV
We report on a search for bottom squarks produced in pbarp collisions at
sqrt(s) = 1.8 TeV using the D0 detector at Fermilab. Bottom squarks are assumed
to be produced in pairs and to decay to the lightest supersymmetric particle
(LSP) and a b quark with branching fraction of 100%. The LSP is assumed to be
the lightest neutralino and stable. We set limits on the production cross
section as a function of bottom squark mass and LSP mass.Comment: 5 pages, Latex. submitted 3-12-1999 to PRD - Rapid Communicatio
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