381 research outputs found
Initial study on phytoextraction for recovery of metals from sorted and aged wasteâtoâenergy bottom ash
Sorted and aged bottom ash from WasteâtoâEnergy plants, i.e., MIBA (the Mineral fraction of Incinerator Bottom Ash) are potential source of metals that could be utilized to meet the increased demand from society. In this work, sunflowers (Helianthus annuus) and rapeseed (Brassica napus) were cultivated in conventional MIBA to evaluate the possibility for phytoextraction, mainly of Zn, during the period of one cultivation season in the Nordic climate. The results show that metal extraction from MIBA using rapeseed and sunflowers is workable but that neither of the used plants is optimal, mainly due to the inhibited root development and low waterâ and nutrientâholding capacities of MIBA. The addition of fertilizer is also important for growth. There was a simultaneous accumulation of numerous metals in both plant types, and the highest metal content was generally found in the roots. Calculations indicated that the ash from rapeseed root incineration contained about 2% Zn, and the contents of Co, Cu, and Pb were comparable to those in workable ores. This initial study shows that cultivation in and phytoextraction on MIBA is possible, and that the potential for increased metal extraction is high
Finding cool subdwarfs using a V-J reduced proper-motion diagram: Stellar parameters for 91 candidates
We present the results of a search for cool subdwarfs for which our
candidates were drawn from a V-J reduced proper-motion diagram constructed by
Salim & Gould (2002). Kinematic (U, V, and W) and self-consistent stellar
parameters (Teff, log g, [Fe/H], and V_t) are derived for 91 candidate
subdwarfs based on high resolution spectra. The observed stars span 3900K <
Teff < 6200K and -2.63 < [Fe/H] < 0.25 including only 3 giants (log g < 4.0).
Of the sample, 77 stars have MgH lines present in their spectra. With more than
56% of our candidate subdwarfs having [Fe/H] < -1.5, we show that the V-J
reduced proper-motion diagram readily identifies metal-poor stars.Comment: PASP (in press
The Interstellar Rubidium Isotope Ratio toward Rho Ophiuchi A
The isotope ratio, 85Rb/87Rb, places constraints on models of the
nucleosynthesis of heavy elements, but there is no precise determination of the
ratio for material beyond the Solar System. We report the first measurement of
the interstellar Rb isotope ratio. Our measurement of the Rb I line at 7800 A
for the diffuse gas toward rho Oph A yields a value of 1.21 +/- 0.30 (1-sigma)
that differs significantly from the meteoritic value of 2.59. The Rb/K
elemental abundance ratio for the cloud also is lower than that seen in
meteorites. Comparison of the 85Rb/K and 87Rb/K ratios with meteoritic values
indicates that the interstellar 85Rb abundance in this direction is lower than
the Solar System abundance. We attribute the lower abundance to a reduced
contribution from the r-process. Interstellar abundances for Kr, Cd, and Sn are
consistent with much less r-process synthesis for the solar neighborhood
compared to the amount inferred for the Solar System.Comment: 12 pages with 2 figures and 1 table; will appear in ApJ Letter
The Perceived Support From Light and Color Before and After an Evidence-Based Design Intervention in an Emergency Department Environment: A Quasi-Experimental Study
Aim: To evaluate patientsâ and family membersâ perceived support from light and color before, compared with after an evidence-based design (EBD) intervention at an emergency department (ED) using a validated instrumentâthe Light and Color Questionnaire (LCQ). Background: EDs offer acute care day and night. Thus, a supportive physical environment where light and color is crucial for how the milieu is experienced is vital. Research is limited on how care settings are perceived as supportive by users. Methods: Quasi-experimental evaluation of the refurbishing and remodeling of an ED by an expert group of nurse managers, nursing staff, nursing researchers and architects in south Sweden. LCQ includes dimensions âmaximizing awareness and orientation,â âmaximizing safety and security,â âsupporting functional abilities,â âproviding privacy,â âopportunities for personal controlâ (not for LCQ-Color), and âregulation and quality of stimulation.â LCQ was analyzed and compared in 400 surveys from 100 patients and 100 family members before the intervention and 100 patients and 100 family members after the intervention. Results: The LCQ total score significantly improved after the intervention for both patients and family members. Four of the six dimensions of LCQ Light subscale scores were significantly higher for family members, and three of the six dimensions were significantly higher for patients after the intervention. The LCQ Color subscale score showed significant improvements for all five dimensions for both patients and family members after the intervention. Conclusion: This study showed improved perceived support from light and color in the physical environment for patients and family members after an EBD intervention at an emergency department using a validated instrumentâthe Light and Color Questionnaire
The Southern Proper Motion Program III. A Near-Complete Catalog to V=17.5
We present the third installment of the Yale/San Juan Southern Proper Motion
Catalog, SPM3. Absolute proper motions, positions, and photographic B,V
photometry are given for roughly 10.7 million objects, primarily stars, down to
a magnitude of V=17.5. The Catalog covers an irregular area of 3700 square
degrees, between the declinations of -20 and -45 degrees, excluding the
Galactic plane. The proper-motion precision, for well-measured stars, is
estimated to be 4.0 mas/yr. Unlike previous releases of the SPM Catalog, the
proper motions are on the International Celestial Reference System by way of
Hipparcos Catalog stars, and have an estimated systematic uncertainty of 0.4
mas/yr. The SPM3 Catalog is available via electronic
transfer,(http://www.astro.yale.edu/astrom/) As an example of the potential of
the SPM3 proper motions, we examine the Galactocentric velocities of a group of
metal-poor, main-sequence A stars. The majority of these exhibit thick-disk
kinematics, lending support to their interpretation as thick-disk blue
stragglers, as opposed to being an accreted component.Comment: 23 pages, 10 figures, accepted for publication in Astronomical
Journa
Boron in Very Metal-Poor Stars
We have observed the B I 2497 A line to derive the boron abundances of two
very metal-poor stars selected to help in tracing the origin and evolution of
this element in the early Galaxy: BD +23 3130 and HD 84937. The observations
were conducted using the Goddard High Resolution Spectrograph on board the
Hubble Space Telescope. A very detailed abundance analysis via spectral
synthesis has been carried out for these two stars, as well as for two other
metal-poor objects with published spectra, using both Kurucz and OSMARCS model
photospheres, and taking into account consistently the NLTE effects on the line
formation. We have also re-assessed all published boron abundances of old disk
and halo unevolved stars. Our analysis shows that the combination of high
effective temperature (Teff > 6000 K, for which boron is mainly ionized) and
low metallicity ([Fe/H]<-1) makes it difficult to obtain accurate estimates of
boron abundances from the B I 2497 A line. This is the case of HD 84937 and
three other published objects (including two stars with [Fe/H] ~ -3), for which
only upper limits can be established. BD +23 3130, with [Fe/H] ~ -2.9 and
logN(B)_NLTE=0.05+/-0.30, appears then as the most metal-poor star for which a
firm measurement of the boron abundance presently exists. The evolution of the
boron abundance with metallicity that emerges from the seven remaining stars
with Teff < 6000 K and [Fe/H]<-1, for which beryllium abundances were derived
using the same stellar parameters, shows a linear increase with a slope ~ 1.
Furthermore, the B/Be ratio found is constant at a value ~ 20 for stars in the
range -3<[Fe/H]<-1. These results point to spallation reactions of ambient
protons and alpha particles with energetic particles enriched in CNO as the
origin of boron and beryllium in halo stars.Comment: 38 pages, 11 Encapsulated Postscript figures (included), uses
aaspp4.sty. Accepted for publication in The Astrophysical Journal. The
preprint is also available at: http://www.iac.es/publicaciones/preprints.htm
Constraining the Metallicity of the Low Density Lyman-alpha Forest Using OVI Absorption
We search for OVI absorption in a Keck HIRES spectrum of the z=3.62 quasar
Q1422+231. Comparison of CIV measurements to cosmological simulations shows
that \lya forest absorbers with N_HI > 10^{14.5} have [C/H]~=-2.5, for the UV
background spectrum of Haardt & Madau (HM). Lower column density absorption
arises in lower density gas, where OVI is the most sensitive metal tracer.
Since OVI lines lie at wavelengths contaminated by Lyman series absorption, we
interpret our Q1422 results by comparing to artificial spectra drawn from an
SPH simulation of a Lambda-dominated CDM model. A search for deep, narrow
features in Q1422 yields only a few candidate OVI lines, statistically
consistent with the number in artificial spectra with no metals; spectra
generated with the HM background and [O/H] >= -2.5 predict too many narrow
lines. However, applying the optical depth ratio technique of Songaila (1998),
we DO find significant OVI associated with CIV systems; matching Q1422 requires
[O/C]~=+0.5, implying [O/H]~=-2.0. Taken together these results imply that (a)
the metallicity in the low density IGM is at least a factor of three below that
in the overdense regions where CIV absorption is detectable, and (b) oxygen is
overabundant in these regions, consistent with the enrichment pattern of old
halo stars. If the UV background is heavily truncated above 4 Ry, an
implausibly high oxygen overabundance ([O/C]>+2) is required by the data; thus
a majority of the volume of the universe must have undergone helium
reionization by z=3.(Abridged)Comment: Submitted to ApJ, 48 pp including 14 ps figures, uses aaspp4.st
Lithium in Blanco1: Implications for Stellar Mixing
We obtain lithium abundances for G and K stars in Blanco 1, an open cluster
with an age similar to, or slightly younger than, the Pleiades. We critically
examine previous spectroscopic abundance analyses of Blanco 1 and conclude that
while there were flaws in earlier work, it is likely that Blanco 1 is close in
overall metallicity to the older Hyades cluster and more metal-rich than the
Pleiades. However, we find Blanco 1 has Li abundances and rotation rates
similar to the Pleiades, contradicting predictions from standard stellar
evolution models, in which convective pre-main sequence (PMS) Li depletion
should increase rapidly with metallicity. If the high metallicity of Blanco 1
is subsequently confirmed, our observations imply (1) that a currently unknown
mechanism severely inhibits PMS Li depletion, (2) that additional non-standard
mixing modes, such as those driven by rotation and angular momentum loss, are
then responsible for main sequence Li depletion between the ages of Blanco 1
and the Hyades, and (3) that in clusters younger than the Hyades, metallicity
plays only a minor role in determining the amount of Li depletion among G and K
stars. These conclusions suggest that Li abundance remains a useful age
indicator among young (less than 700 Myr) stars even when metallicities are
unknown. If non-standard mixing is effective in Population I stars, the
primordial Li abundance could be significantly larger than present day
Population II Li abundances, due to prior Li depletion.Comment: 18 pages, 3 figs. To appear in ApJ Vol. 511 (Jan 20 1999
Personalized Nursing and Health Care: Advancing Positive Patient Outcomes in Complex and Multilevel Care Environments
This Special Issue of the Journal of Personalised Medicine invited manuscripts that further establish the current state of science relating to personalized nursing and health care [...
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