Toward a script theory of guidance in computer-supported collaborative learning

This article presents an outline of a script theory of guidance for computer-supported collaborative learning (CSCL). With its four types of components of internal and external scripts (play, scene, role, and scriptlet) and seven principles, this theory addresses the question how CSCL practices are shaped by dynamically re-configured internal collaboration scripts of the participating learners. Furthermore, it explains how internal collaboration scripts develop through participation in CSCL practices. It emphasizes the importance of active application of subject matter knowledge in CSCL practices, and it prioritizes transactive over non-transactive forms of knowledge application in order to facilitate learning. Further, the theory explains how external collaboration scripts modify CSCL practices and how they influence the development of internal collaboration scripts. The principles specify an optimal scaffolding level for external collaboration scripts and allow for the formulation of hypotheses about the fading of external collaboration scripts. Finally, the article points towards conceptual challenges and future research questions

PIXE micro-PIXE and RBS analysis of thermal aged rubber material : on the additive behaviour versus aging time

BIA

Linking stellar mass and star formation in Spitzer/MIPS 24 micron galaxies

We present deep Ks<21.5 (Vega) identifications, redshifts and stellar masses for most of the sources composing the bulk of the 24 micron background in the GOODS/CDFS. Our identified sample consists of 747 Spitzer/MIPS 24 micron objects, and includes ~94% of all the 24 micron sources in the GOODS-South field which have fluxes Snu(24)>83 microJy (the 80% completeness limit of the Spitzer/GTO 24 micron catalog). 36% of our galaxies have spectroscopic redshifts (mostly at z<1.5) and the remaining ones have photometric redshifts of very good quality, with a median of |dz|=|zspec-zphot|/(1+zspec)=0.02. We find that MIPS 24 micron galaxies span the redshift range z~0-4, and that a substantial fraction (28%) lie at high redshifts z>1.5. We determine the existence of a bump in the redshift distribution at z~1.9, indicating the presence of a significant population of galaxies with PAH emission at these redshifts. Massive (M>10^11 Msun) star-forming galaxies at redshifts 2<z<3 are characterized by very high star-formation rates (SFR>500 Msun/yr), and some of them are able to construct a mass of 10^10-10^11 Msun in a single burst lifetime (~0.01-0.1 Gyr). At lower redshifts z<2, massive star-forming galaxies are also present, but appear to be building their stars on long timescales, either quiescently or in multiple modest burst-like episodes. At redshifts z~1-2, the ability of the burst-like mode to produce entire galaxies in a single event is limited to some lower (M<7x10^10 Msun) mass systems, and it is basically negligible at z<1. Our results support a scenario where star-formation activity is differential with assembled stellar mass and redshift, and where the relative importance of the burst-like mode proceeds in a down-sizing way from high to low redshifts. (abridged)Comment: Accepted for publication in the ApJ. 19 pages, 10 figures. Uses emulateap

Comparison of absolute gain photometric calibration between Planck/HFI and Herschel/SPIRE at 545 and 857 GHz

We compare the absolute gain photometric calibration of the Planck/HFI and Herschel/SPIRE instruments on diffuse emission. The absolute calibration of HFI and SPIRE each relies on planet flux measurements and comparison with theoretical far-infrared emission models of planetary atmospheres. We measure the photometric cross calibration between the instruments at two overlapping bands, 545 GHz / 500 $\mu$m and 857 GHz / 350 $\mu$m. The SPIRE maps used have been processed in the Herschel Interactive Processing Environment (Version 12) and the HFI data are from the 2015 Public Data Release 2. For our study we used 15 large fields observed with SPIRE, which cover a total of about 120 deg^2. We have selected these fields carefully to provide high signal-to-noise ratio, avoid residual systematics in the SPIRE maps, and span a wide range of surface brightness. The HFI maps are bandpass-corrected to match the emission observed by the SPIRE bandpasses. The SPIRE maps are convolved to match the HFI beam and put on a common pixel grid. We measure the cross-calibration relative gain between the instruments using two methods in each field, pixel-to-pixel correlation and angular power spectrum measurements. The SPIRE / HFI relative gains are 1.047 ($\pm$ 0.0069) and 1.003 ($\pm$ 0.0080) at 545 and 857 GHz, respectively, indicating very good agreement between the instruments. These relative gains deviate from unity by much less than the uncertainty of the absolute extended emission calibration, which is about 6.4% and 9.5% for HFI and SPIRE, respectively, but the deviations are comparable to the values 1.4% and 5.5% for HFI and SPIRE if the uncertainty from models of the common calibrator can be discounted. Of the 5.5% uncertainty for SPIRE, 4% arises from the uncertainty of the effective beam solid angle, which impacts the adopted SPIRE point source to extended source unit conversion factor (Abridged)Comment: 13 pages, 10 figures; Incorporates revisions in response to referee comments; cross calibration factors unchange

Serodiagnosis of leishmaniasis with recombinant ORFF antigen

The serodiagnostic potential of recombinant ORFF protein (rORFF) from Leishmania infantum was assessed by ELISA. Of 49 sera from confirmed cases of visceral leishmaniasis (VL), all were seropositive using 5 ng of rORFF and serum diluted 1:20, while only 38 were positive with 500 ng of soluble antigen (SA) and 44 were positive by a direct agglutination test. There was also a positive correlation between spleen size and level of seropositivity with rORFF or SA. The reciprocal endpoint titer with rORFF was 1,280 for sera from VL patients, but &lt; 20 with sera from malaria, filariasis, and tuberculosis patients, as well as with sera from healthy individuals from endemic and non-endemic areas. Sera from 10 confirmed cutaneous leishmaniasis cases from Turkey were negative or only weakly positive with rORFF although 9 were positive with SA. Thus, rORFF protein appears useful as a sensitive reagent for the differential diagnosis of VL caused by the Leishmania donovani complex

The infrared luminosity function of galaxies at redshifts z=1 and z~2 in the GOODS fields

We present the rest-frame 8 micron luminosity function (LF) at redshifts z=1 and ~2, computed from Spitzer 24 micron-selected galaxies in the GOODS fields over an area of 291 sq. arcmin. Using classification criteria based on X-ray data and IRAC colours, we identify the AGN in our sample. The rest-frame 8 micron LF for star-forming galaxies at redshifts z=1 and ~2 have the same shape as at z~0, but with a strong positive luminosity evolution. The number density of star-forming galaxies with log_{10}(nu L_nu(8 micron))>11 increases by a factor >250 from redshift z~0 to 1, and is basically the same at z=1 and ~2. The resulting rest-frame 8 micron luminosity densities associated with star formation at z=1 and ~2 are more than four and two times larger than at z~0, respectively. We also compute the total rest-frame 8 micron LF for star-forming galaxies and AGN at z~2 and show that AGN dominate its bright end, which is well-described by a power-law. Using a new calibration based on Spitzer star-forming galaxies at 0<z<0.6 and validated at higher redshifts through stacking analysis, we compute the bolometric infrared (IR) LF for star-forming galaxies at z=1 and ~2. We find that the respective bolometric IR luminosity densities are (1.2+/-0.2) x 10^9 and (6.6^{+1.2}_{-1.0}) x 10^8 L_sun Mpc^{-3}, in agreement with previous studies within the error bars. At z~2, around 90% of the IR luminosity density associated with star formation is produced by luminous and ultraluminous IR galaxies (LIRG and ULIRG), with the two populations contributing in roughly similar amounts. Finally, we discuss the consistency of our findings with other existing observational results on galaxy evolution.Comment: Accepted for publication in the ApJ. 33 pages, 15 figures. Uses emulateap

GOODS-HerschelHerschel: identification of the individual galaxies responsible for the 80-290μ\mum cosmic infrared background

We propose a new method of pushing $Herschel$ to its faintest detection limits using universal trends in the redshift evolution of the far infrared over 24$\mu$m colours in the well-sampled GOODS-North field. An extension to other fields with less multi-wavelength information is presented. This method is applied here to raise the contribution of individually detected $Herschel$ sources to the cosmic infrared background (CIRB) by a factor 5 close to its peak at 250$\mu$m and more than 3 in the 350$\mu$m and 500$\mu$m bands. We produce realistic mock $Herschel$ images of the deep PACS and SPIRE images of the GOODS-North field from the GOODS-$Herschel$ Key Program and use them to quantify the confusion noise at the position of individual sources, i.e., estimate a "local confusion noise". Two methods are used to identify sources with reliable photometric accuracy extracted using 24$\mu$m prior positions. The clean index (CI), previously defined but validated here with simulations, which measures the presence of bright 24$\mu$m neighbours and the photometric accuracy index (PAI) directly extracted from the mock $Herschel$ images. After correction for completeness, thanks to our mock $Herschel$ images, individually detected sources make up as much as 54% and 60% of the CIRB in the PACS bands down to 1.1 mJy at 100$\mu$m and 2.2 mJy at 160$\mu$m and 55, 33, and 13% of the CIRB in the SPIRE bands down to 2.5, 5, and 9 mJy at 250$\mu$m, 350$\mu$m, and 500$\mu$m, respectively. The latter depths improve the detection limits of $Herschel$ by factors of 5 at 250$\mu$m, and 3 at 350$\mu$m and 500$\mu$m as compared to the standard confusion limit. Interestingly, the dominant contributors to the CIRB in all $Herschel$ bands appear to be distant siblings of the Milky Way ($z$$\sim$0.96 for $\lambda$$<$300$\mu$m) with a stellar mass of $M_{\star}$$\sim$9$\times$10$^{10}$M$_{\odot}$.Comment: 22 pages, 16 figures. Accepted for publication by Astronomy and Astrophysic

Search for Radiative Decays of Cosmic Background Neutrino using Cosmic Infrared Background Energy Spectrum

We propose to search for the neutrino radiative decay by fitting a photon energy spectrum of the cosmic infrared background to a sum of the photon energy spectrum from the neutrino radiative decay and a continuum. By comparing the present cosmic infrared background energy spectrum observed by AKARI and Spitzer to the photon energy spectrum expected from neutrino radiative decay with a maximum likelihood method, we obatined a lifetime lower limit of $3.1 \times 10^{12}$ to $3.8 \times 10^{12}$ years at 95% confidence level for the third generation neutrino $\nu_3$ in the $\nu_3$ mass range between 50 \mmev and 150 \mmev under the present constraints by the neutrino oscillation measurements. In the left-right symmetric model, the minimum lifetime of $\nu_3$ is predicted to be $1.5 \times 10^{17}$ years for $m_3$ of 50 \mmev. We studied the feasibility of the observation of the neutrino radiative decay with a lifetime of $1.5 \times 10^{17}$ years, by measuring a continuous energy spectrum of the cosmic infrared background

The role of the LIRG and ULIRG phases in the evolution of Ks-selected galaxies

We investigate the role of the luminous infrared galaxy (LIRG) and ultra-luminous infrared galaxy (ULIRG) phases in the evolution of Ks-selected galaxies and, in particular, Extremely Red Galaxies (ERGs). With this aim, we compare the properties of a sample of 2905 Ks<21.5 (Vega mag) galaxies in the GOODS/CDFS with the sub-sample of those 696 sources which are detected at 24 microns. We find that LIRGs constitute 30% of the galaxies with stellar mass M>1x10^{11} Msun assembled at redshift z=0.5. A minimum of 65% of the galaxies with M>2.5x10^{11} Msun at z~2-3 are ULIRGs at those redshifts. 60% of the ULIRGs in our sample have the characteristic colours of ERGs. Conversely, 40% of the ERGs with stellar mass M>1.3x10^{11} Msun at 1.5<z<2.0 and a minimum of 52% of those with the same mass cut at 2.0<z<3.0 are ULIRGs. The average optical/near-IR properties of the massive ERGs at similar redshifts that are identified with ULIRGs and that are not have basically no difference, suggesting that both populations contain the same kind of objects in different phases of their lives. LIRGs and ULIRGs have an important role in galaxy evolution and mass assembly, and, although they are only able to trace a fraction of the massive (M>1x10^{11} Msun) galaxies present in the Universe at a given time, this fraction becomes very significant (>50%) at redshifts z>~2.Comment: Accepted for publication in A&A. 9 pages, 6 figure