979 research outputs found

    Properties of the ground 3^3F2_2 state and the excited 3^3P0_0 state of atomic thorium in cold collisions with 3^3He

    Full text link
    We measure inelastic collisional cross sections for the ground 3^3F2_2 state and the excited 3^3P0_0 state of atomic thorium in cold collisions with 3^3He. We determine for Th (3^3F2_2) at 800 mK the ratio γ500\gamma \approx 500 of the momentum-transfer to Zeeman relaxation cross sections for collisions with 3^3He. For Th (3^3P0_0), we study electronic inelastic processes and find no quenching even after 10610^6 collisions. We also determine the radiative lifetime of Th (3^3P0_0) to be τ>130\tau > 130 ms. This great stability of the metastable state opens up the possibility for further study, including trapping

    Vibrational quenching of the electronic ground state in ThO in cold collisions with 3^3He

    Full text link
    We measure the ratio γ\gamma of the momentum-transfer to the vibrational quenching cross section for the X (1Σ+^1\Sigma^+), ν=1\nu=1, J=0\mathrm{J=0} state of molecular thorium monoxide (ThO) in collisions with atomic 3^3He between 800 mK and 2.4 K. We observe indirect evidence for ThO--He van der Waals' complex formation, which has been predicted by theory. We determine the 3-body recombination rate constant Γ3\Gamma_3 at 2.4 K, and establish that the binding energy Eb>_b > 4 K

    Large spin relaxation rates in trapped submerged-shell atoms

    Get PDF
    Spin relaxation due to atom-atom collisions is measured for magnetically trapped erbium and thulium atoms at a temperature near 500 mK. The rate constants for Er-Er and Tm-Tm collisions are 3.0 times 10^-10 cm^3 s^-1 and 1.1 times 10^-10 cm^3 s^-1, respectively, 2-3 orders of magnitude larger than those observed for highly magnetic S-state atoms. This is strong evidence for an additional, dominant, spin relaxation mechanism, electrostatic anisotropy, in collisions between these "submerged-shell" L > 0 atoms. These large spin relaxation rates imply that evaporative cooling of these atoms in a magnetic trap will be highly inefficient.Comment: 10 pages, 3 figure

    Spectral Decomposition of Broad-Line AGNs and Host Galaxies

    Full text link
    Using an eigenspectrum decomposition technique, we separate the host galaxy from the broad line active galactic nucleus (AGN) in a set of 4666 spectra from the Sloan Digital Sky Survey (SDSS), from redshifts near zero up to about 0.75. The decomposition technique uses separate sets of galaxy and quasar eigenspectra to efficiently and reliably separate the AGN and host spectroscopic components. The technique accurately reproduces the host galaxy spectrum, its contributing fraction, and its classification. We show how the accuracy of the decomposition depends upon S/N, host galaxy fraction, and the galaxy class. Based on the eigencoefficients, the sample of SDSS broad-line AGN host galaxies spans a wide range of spectral types, but the distribution differs significantly from inactive galaxies. In particular, post-starburst activity appears to be much more common among AGN host galaxies. The luminosities of the hosts are much higher than expected for normal early-type galaxies, and their colors become increasingly bluer than early-type galaxies with increasing host luminosity. Most of the AGNs with detected hosts are emitting at between 1% and 10% of their estimated Eddington luminosities, but the sensitivity of the technique usually does not extend to the Eddington limit. There are mild correlations among the AGN and host galaxy eigencoefficients, possibly indicating a link between recent star formation and the onset of AGN activity. The catalog of spectral reconstruction parameters is available as an electronic table.Comment: 18 pages; accepted for publication in A

    Treatment algorithm for infants diagnosed with spinal muscular atrophy through newborn screening

    Get PDF
    Spinal muscular atrophy (SMA) is an autosomal recessive disease characterized by the degeneration of alpha motor neurons in the spinal cord, leading to muscular atrophy. SMA is caused by deletions or mutations in the survival motor neuron 1 gene (SMN1). In humans, a nearly identical copy gene, SMN2, is present. Because SMN2 has been shown to decrease disease severity in a dose-dependent manner, SMN2 copy number is predictive of disease severity. To develop a treatment algorithm for SMA-positive infants identified through newborn screening based upon SMN2 copy number. A working group comprised of 15 SMA experts participated in a modified Delphi process, moderated by a neutral third-party expert, to develop treatment guidelines. The overarching recommendation is that all infants with two or three copies of SMN2 should receive immediate treatment (n = 13). For those infants in which immediate treatment is not recommended, guidelines were developed that outline the timing and appropriate screens and tests to be used to determine the timing of treatment initiation. The identification SMA affected infants via newborn screening presents an unprecedented opportunity for achievement of maximal therapeutic benefit through the administration of treatment pre-symptomatically. The recommendations provided here are intended to help formulate treatment guidelines for infants who test positive during the newborn screening process

    Semiautomated Glasgow-Blatchford Bleeding Score helps direct bed placement for patients with upper gastrointestinal bleeding.

    Get PDF
    OBJECTIVE: The Glasgow-Blatchford Bleeding Score (GBS) was designed to identify patients with upper gastrointestinal bleeding (UGIB) who do not require hospitalisation. It may also help stratify patients unlikely to benefit from intensive care. DESIGN: We reviewed patients assigned a GBS in the emergency room (ER) via a semiautomated calculator. Patients with a score ≤7 (low risk) were directed to an unmonitored bed (UMB), while those with a score of ≥8 (high risk) were considered for MB placement. Conformity with guidelines and subsequent transfers to MB were reviewed, along with transfusion requirement, rebleeding, length of stay, need for intervention and death. RESULTS: Over 34 months, 1037 patients received a GBS in the ER. 745 had an UGIB. 235 (32%) of these patients had a GBS ≤7. 29 (12%) low-risk patients were admitted to MBs. Four low-risk patients admitted to UMB required transfer to MB within the first 48 hours. Low-risk patients admitted to UMBs were no more likely to die, rebleed, need transfusion or require more endoscopic, radiographic or surgical procedures than those admitted to MBs. No low-risk patient died from GIB. Patients with GBS ≥8 were more likely to rebleed, require transfusion and interventions to control bleeding but not to die. CONCLUSION: A semiautomated GBS calculator can be incorporated into an ER workflow. Patients with a GBS ≤7 are unlikely to need MB care for UGIB. Further studies are warranted to determine an ideal scoring system for MB admission

    The effects of composition and thermal path on hot ductility of forging steels

    Get PDF
    This work examines the effects of composition and thermal handling path on the hot ductility of as-cast steelforging ingots. Poor ductility of the as-cast structure can lead to cracking of the ingot prior to forging or theformation of tears early during the forging process. The as-cast structure is particularly susceptible to crackingdue to the large grain size and high degree of microsegregation present.Experiments were conducted to evaluate the ductility of the as-cast steel with varying levels aluminum andnitrogen. Multiple thermal handling paths were followed in order to approximate the different thermal conditionsexperienced approximately six inches below the surface of a large (~40 MT) steel ingot following solidification.Hot tension testing after in-situ melting and solidification was used for quantitative measurements of thematerial ductility. The majority of testing was carried out on a modified P20 mild tool steel. The experimentsindicate a significant loss of ductility for materials with high aluminum and nitrogen contents(AlxN = 5.2x10-4) in the temperature range of 950 °C - 1050 °C upon solidification and direct cooling to thetest temperature. This behavior is not present in material with AlxN products below 1.3x10-4. All materialstested exhibited a loss of ductility when the sample was cooled to 900 °C, immediately reheated to 1000°C andtested. With increasing hold times at 900 °C prior to reheating to 1000 °C, the material with high aluminum andnitrogen contents recovers ductility much more quickly than the low aluminum and nitrogen materials.Funding in part by the Forging Industry Educational & Research Foundation and Ellwood Group, Inc

    Motavizumab, A Neutralizing Anti-Respiratory Syncytial Virus (Rsv) Monoclonal Antibody Significantly Modifies The Local And Systemic Cytokine Responses Induced By Rsv In The Mouse Model

    Get PDF
    Motavizumab (MEDI-524) is a monoclonal antibody with enhanced neutralizing activity against RSV. In mice, motavizumab suppressed RSV replication which resulted in significant reduction of clinical parameters of disease severity. We evaluated the effect of motavizumab on the local and systemic immune response induced by RSV in the mouse model. Balb/c mice were intranasally inoculated with 106.5 PFU RSV A2 or medium. Motavizumab was given once intraperitoneally (1.25 mg/mouse) as prophylaxis, 24 h before virus inoculation. Bronchoalveolar lavage (BAL) and serum samples were obtained at days 1, 5 (acute) and 28 (long-term) post inoculation and analyzed with a multiplex assay (Beadlyte Upstate, NY) for simultaneous quantitation of 18 cytokines: IL-1α, IL-1β, IL-2, IL-3, IL-4, IL-5, IL-6, KC (similar to human IL-8), IL-10, IL-12p40, IL-12p70, IL-13, IL-17, TNF-α, MCP-1, RANTES, IFN-γ and GM-CSF. Overall, cytokine concentrations were lower in serum than in BAL samples. By day 28, only KC was detected in BAL specimens at low concentrations in all groups. Administration of motavizumab significantly reduced (p < 0.05) BAL concentrations of IL-1α, IL-12p70 and TNF-α on day 1, and concentrations of IFN-γ on days 1 and 5 compared with RSV-infected untreated controls. In the systemic compartment, the concentrations of IL-10, IFN-γ and KC were significantly reduced in the motavizumab-treated mice compared with the untreated controls. In summary, prophylactic administration of motavizumab was associated with significant reductions on RSV replication and concentrations of cytokine and chemokines, which are likely related to the improvement observed in clinical markers of disease severity

    Human Mars Mission Design - The Ultimate Systems Challenge

    Get PDF
    A human mission to Mars will occur at some time in the coming decades. When it does, it will be the end result of a complex network of interconnected design choices, systems analyses, technical optimizations, and non-technical compromises. This mission will extend the technologies, engineering design, and systems analyses to new limits, and may very well be the most complex undertaking in human history. It can be illustrated as a large menu, or as a large decision tree. Whatever the visualization tool, there are numerous design decisions required to assemble a human Mars mission, and many of these interconnect with one another. This paper examines these many decisions and further details a number of choices that are highly interwoven throughout the mission design. The large quantity of variables and their interconnectedness results in a highly complex systems challenge, and the paper illustrates how a change in one variable results in ripples (sometimes unintended) throughout many other facets of the design. The paper concludes with a discussion of some mission design variables that can be addressed first, and those that have already been addressed as a result of ongoing National Aeronautics and Space Administration (NASA) developments, or as a result of decisions outside the technical arena. It advocates the need for a 'reference design' that can be used as a point of comparison, and to illustrate the system-wide impacts as design variables change

    Permeability of Noble Gases through Kapton, Butyl, Nylon, and "Silver Shield"

    Get PDF
    Noble gas permeabilities and diffusivities of Kapton, butyl, nylon, and "Silver Shield" are measured at temperatures between 22C and 115C. The breakthrough times and solubilities at 22C are also determined. The relationship of the room temperature permeabilities to the noble gas atomic radii is used to estimate radon permeability for each material studied. For the noble gases tested, Kapton and Silver Shield have the lowest permeabilities and diffusivities, followed by nylon and butyl, respectively.Comment: 14 pages, 7 figure
    corecore