Children who cannot read: a study of their home environment

Thesis (M.S.)--Boston University, 1943. This item was digitized by the Internet Archive

A distance-limited sample of massive star-forming cores from the RMS survey

We analyse C18O (J = 3−2) data from a sample of 99 infrared (IR)-bright massive young stellar objects (MYSOs) and compact H ii regions that were identified as potential molecular-outflow sources in the Red MSX Source survey. We extract a distance-limited (D < 6 kpc) sample shown to be representative of star formation covering the transition between the source types. At the spatial resolution probed, Larson-like relationships are found for these cores, though the alternative explanation, that Larson's relations arise where surface-density-limited samples are considered, is also consistent with our data. There are no significant differences found between source properties for the MYSOs and H ii regions, suggesting that the core properties are established prior to the formation of massive stars, which subsequently have little impact at the later evolutionary stages investigated. There is a strong correlation between dust-continuum and C18O-gas masses, supporting the interpretation that both trace the same material in these IR-bright sources. A clear linear relationship is seen between the independently established core masses and luminosities. The position of MYSOs and compact H ii regions in the mass–luminosity plane is consistent with the luminosity expected from a cluster of protostars when using an ∼40 per cent star formation efficiency and indicates that they are at a similar evolutionary stage, near the end of the accretion phase

Observatoire Scientifique en Appui à la GEstion du territoire (OSAGE) : entre espaces, temps, milieux, sociétés et informatique

L'article constitue une réflexion globale et conceptuelle autour de la notion d'observatoire scientifique en appui à la gestion du territoire. Il est le fruit d'une réflexion interdisciplinaire. Le terme observatoire recouvre de nombreuses acceptions et, à l'heure actuelle, de nombreuses réalisations existent sous diverses formes. Notre objectif est de tirer parti de la synergie entre scientifiques de divers domaines afin de prendre en compte la valeur ajoutée que constitue l'expertise scientifique pour clarifier la définition et les principes constitutifs fondamentaux de tels systèmes. Nous déclinons la vision de ce type d'observatoire au travers d&#8217;une approche conceptuelle. L'accent est mis sur le dispositif scientifique, et la déclinaison technique envisagée

An injectable bone marrow-like scaffold enhances T cell immunity after hematopoietic stem cell transplantation.

Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative treatment for multiple disorders, but deficiency and dysregulation of T cells limit its utility. Here we report a biomaterial-based scaffold that mimics features of T cell lymphopoiesis in the bone marrow. The bone marrow cryogel (BMC) releases bone morphogenetic protein-2 to recruit stromal cells and presents the Notch ligand Delta-like ligand-4 to facilitate T cell lineage specification of mouse and human hematopoietic progenitor cells. BMCs subcutaneously injected in mice at the time of HSCT enhanced T cell progenitor seeding of the thymus, T cell neogenesis and diversification of the T cell receptor repertoire. Peripheral T cell reconstitution increased ~6-fold in mouse HSCT and ~2-fold in human xenogeneic HSCT. Furthermore, BMCs promoted donor CD4+ regulatory T cell generation and improved survival after allogeneic HSCT. In comparison to adoptive transfer of T cell progenitors, BMCs increased donor chimerism, T cell generation and antigen-specific T cell responses to vaccination. BMCs may provide an off-the-shelf approach for enhancing T cell regeneration and mitigating graft-versus-host disease in HSCT

Measurement of fast and thermal neutron flux from the d + D reaction using the activation method

LPSC-acc ;

The Origins of [CII] Emission in Local Star-forming Galaxies

The [CII] 158um fine-structure line is the brightest emission line observed in local star-forming galaxies. As a major coolant of the gas-phase interstellar medium, [CII] balances the heating, including that due to far-ultraviolet photons, which heat the gas via the photoelectric effect. However, the origin of [CII] emission remains unclear, because C+ can be found in multiple phases of the interstellar medium. Here we measure the fractions of [CII] emission originating in the ionized and neutral gas phases of a sample of nearby galaxies. We use the [NII] 205um fine-structure line to trace the ionized medium, thereby eliminating the strong density dependence that exists in the ratio of [CII]/[NII] 122um. Using the FIR [CII] and [NII] emission detected by the KINGFISH and Beyond the Peak Herschel programs, we show that 60-80% of [CII] emission originates from neutral gas. We find that the fraction of [CII] originating in the neutral medium has a weak dependence on dust temperature and the surface density of star formation, and a stronger dependence on the gas-phase metallicity. In metal-rich environments, the relatively cooler ionized gas makes substantially larger contributions to total [CII] emission than at low abundance, contrary to prior expectations. Approximate calibrations of this metallicity trend are provided.Comment: 8 pages, accepted for publication in Ap

Shape Deformation driven Structural Transitions in Quantum Hall Skyrmions

The Quantum Hall ground state away from $\nu = 1$ can be described by a collection of interacting skyrmions. We show within the context of a nonlinear sigma model, that the classical ground state away from $\nu = 1$ is a skyrmion crystal with a generalized N\'eel order. We show that as a function of filling $\nu$, the skyrmion crystal undergoes a triangle to square to triangle transition at zero temperature. We argue that this structural transition, driven by a change in the shape of the individual skyrmions, is stable to thermal and quantum fluctuations and may be probed experimentally.Comment: 4 pages (REVTEX) and 4 .eps figure

Infall and outflow motions towards a sample of massive star-forming regions from the RMS survey

We present the results of an outflow and infall survey towards a distance-limited sample of 31 massive st ar-forming regions drawn from the Red MSX source (RMS) survey. The presence of young, active outflows is identified from SiO (8-7) emission and the infall dynamics are explored using HCO + /H 13 CO + (4-3) emission. We investigate if the infall and outflow parameters vary with source properties, exploring whether regions hosting potentially young active outflows show similarities or differences with regions harbouring more evolved, possibly momentum-driven, 'fossil' outflows. SiO emission is detected towards approximately 46 per cent of the sources. When considering sources with and without an SiO detection (i.e. potentially active and fossil outflows, respectively), only the 12 CO outflow velocity shows a significant difference between samples, indicating SiO is more prevalent towards sources with higher outflow velocities. Furthermore, we find the SiO luminosity increases as a function of the Herschel 70 μm to WISE 22 μm flux ratio, suggesting the production of SiO is prevalent in younger, more embedded regions. Similarly, we find tentative evidence that sources with an SiO detection have a smaller bolometric luminosity-to-mass ratio, indicating SiO (8-7) emission is associated with potentially younger regions. We do not find a prevalence towards sources displaying signatures of infall in our sample. However, the higher energy HCO + transitions may not be the best suited tracer of infall at this spatial resolution in these regions. © 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society