52 research outputs found
H I studies of the sculptor group galaxies
Results from large-scale mapping of the H I gas in the Sculptor group are presented. From this kinematic analysis, a mean global (M/L sub B) approx. equals 9 solar maximum/solar luminosity (at the last observed velocity point) is found for the individual galaxies. This is only a factor approx. 10 smaller than the (M/L sub B) dyn approx. equals 90 solar maximum/solar luminosity derived from a dynamical study of the whole group. The parameters derived from the mass models suggest that most of the unseen matter has to be concentrated around the luminous galaxies. Under the assumption that the Sculptor group is a virialized system and that all the mass is associated with the galaxies, an upper limit of approx. 40 kpc is derived for the size of the dark halos present in the five late-type spirals of the group
The Progenitors of Dwarf Spheroidal Galaxies
Dwarf spheroidal (dSph) galaxies present an evolutionary puzzle that we
explore in 40 early- and late-type dwarfs in the Local Group and nearby field.
Although dSphs formed stars over extended periods, today all but one are free
of detectable interstellar matter (ISM), even in the Fornax dSph, where stars
still formed 100 Myr ago. Combining metallicities for red giants with HI data
from the literature, we show that the well-known offset in
luminosity-metallicity (L-Z) relations for dSphs and dwarf irregular (dIrr)
galaxies exists also when comparing only their old stellar populations: dSphs
have higher mean stellar metallicities for a fixed luminosity. Evidently
younger dSphs experienced more efficient enrichment than young dIrrs. Dwarf
galaxies, whose locus in the L-Z diagram is consistent with that of dSphs even
for baryonic luminosities, are the ``transition-type dwarfs'' Phoenix, DDO210,
LGS3, Antlia, and KKR25. They have mixed dIrr/dSph morphologies, low stellar
masses, low angular momentum, and HI contents of less than a few 10^6 solar
masses. Unlike dIrrs, many transition-type dwarfs would closely resemble dSphs
if their gas were removed; they are likely dSph progenitors. As gas removal is
key, we consider the empirical evidence for various gas removal processes. We
suggest that internal gas removal mechanisms are inadequate and favor ram
pressure stripping to make dSphs. A combination of initial conditions and
environment seems to support the formation of dSphs, which appear to form from
small galaxies with active early star formation, whose evolution halts due to
externally induced gas loss. Transition-type dwarfs then are dSphs that kept
their ISM, and therefore should replace dSphs in isolated locations where
stripping is ineffective. (Abridged)Comment: 25 pages in AASTeX two-column preprint style, 1 table, 3 figures.
Accepted for publication in the Astronomical Journal (April 2003 issue
The Sample Analysis at Mars Investigation and Instrument Suite
The Sample Analysis at Mars (SAM) investigation of the Mars Science Laboratory(MSL) addresses the chemical and isotopic composition of the atmosphere and volatilesextracted from solid samples. The SAM investigation is designed to contribute substantiallyto the mission goal of quantitatively assessing the habitability of Mars as an essentialstep in the search for past or present life on Mars. SAM is a 40 kg instrument suite locatedin the interior of MSLs Curiosity rover. The SAM instruments are a quadrupole massspectrometer, a tunable laser spectrometer, and a 6-column gas chromatograph all coupledthrough solid and gas processing systems to provide complementary information on thesame samples. The SAM suite is able to measure a suite of light isotopes and to analyzevolatiles directly from the atmosphere or thermally released from solid samples. In additionto measurements of simple inorganic compounds and noble gases SAM will conducta sensitive search for organic compounds with either thermal or chemical extraction fromsieved samples delivered by the sample processing system on the Curiosity rovers roboticarm
The Milky Way's circular velocity curve between 4 and 14 kpc from APOGEE data
We measure the Milky Way's rotation curve over the Galactocentric range 4 kpc
<~ R <~ 14 kpc from the first year of data from the Apache Point Observatory
Galactic Evolution Experiment (APOGEE). We model the line-of-sight velocities
of 3,365 stars in fourteen fields with b = 0 deg between 30 deg < l < 210 deg
out to distances of 10 kpc using an axisymmetric kinematical model that
includes a correction for the asymmetric drift of the warm tracer population
(\sigma_R ~ 35 km/s). We determine the local value of the circular velocity to
be V_c(R_0) = 218 +/- 6 km/s and find that the rotation curve is approximately
flat with a local derivative between -3.0 km/s/kpc and 0.4 km/s/kpc. We also
measure the Sun's position and velocity in the Galactocentric rest frame,
finding the distance to the Galactic center to be 8 kpc < R_0 < 9 kpc, radial
velocity V_{R,sun} = -10 +/- 1 km/s, and rotational velocity V_{\phi,sun} =
242^{+10}_{-3} km/s, in good agreement with local measurements of the Sun's
radial velocity and with the observed proper motion of Sgr A*. We investigate
various systematic uncertainties and find that these are limited to offsets at
the percent level, ~2 km/s in V_c. Marginalizing over all the systematics that
we consider, we find that V_c(R_0) 99% confidence. We find an
offset between the Sun's rotational velocity and the local circular velocity of
26 +/- 3 km/s, which is larger than the locally-measured solar motion of 12
km/s. This larger offset reconciles our value for V_c with recent claims that
V_c >~ 240 km/s. Combining our results with other data, we find that the Milky
Way's dark-halo mass within the virial radius is ~8x10^{11} M_sun.Comment: submitted to Ap
MeerKAT-16 HI observation of the dIrr galaxy WLM
We present observations and models of the kinematics and the distribution of the
neutral hydrogen (Hi) in the isolated dwarf irregular galaxy, Wolf-Lundmark-Melotte
(WLM). We observed WLM with the Green Bank Telescope (GBT) and as part of
the MeerKAT Early Science Programme, where 16 dishes were available. The Hi disc
of WLM extends out to a major axis diameter of 300 (8.5 kpc), and a minor axis
diameter of 200 (5.6 kpc) as measured by the GBT. We use the MeerKAT data to
model WLM using the TiRiFiC software suite, allowing us to t di erent tilted-ring
models and select the one that best matches the observation. Our nal best- tting
model is a
at disc with a vertical thickness, a constant inclination and dispersion,
and a radially-varying surface brightness with harmonic distortions. To simulate bar-
like motions, we include second-order harmonic distortions in velocity in the tangential
and the vertical directions. We present a model with only circular motions included
and a model with non-circular motions. The latter describes the data better. Overall,
the models reproduce the global distribution and the kinematics of the gas, except for
some faint emission at the 2 level. We model the mass distribution of WLM with a
pseudo-isothermal (ISO) and a Navarro-Frenk-White (NFW) dark matter halo models.
The NFW and the ISO models t the derived rotation curves within the formal errors,
but with the ISO model giving better reduced chi-square values. The mass distribution
in WLM is dominated by dark matter at all radii.The MeerKAT telescope is operated by the South African
Radio Astronomy Observatory, which is a facility of the Na-
tional Research Foundation, an agency of the Department
of Science and Innovation.
This work is based upon research supported by the South
African Research Chairs Initiative of the Department of Sci-
ence and Technology and National Research Foundation.
The nancial assistance of the South African Radio Astron-
omy Observatory (SARAO) towards this research is hereby
acknowledged (www.sarao.ac.za).
PK is partially supported by the BMBF project 05A17PC2
for D-MeerKAT.
AS acknowledges the Russian Science Foundation grant
19-12-00281 and the Program of development of M.V.http://mnras.oxfordjournals.orgam2021Physic
Prediction of Opioid-Induced Respiratory Depression on Inpatient Wards Using Continuous Capnography and Oximetry: An International Prospective, Observational Trial.
BACKGROUND: Opioid-related adverse events are a serious problem in hospitalized patients. Little is known about patients who are likely to experience opioid-induced respiratory depression events on the general care floor and may benefit from improved monitoring and early intervention. The trial objective was to derive and validate a risk prediction tool for respiratory depression in patients receiving opioids, as detected by continuous pulse oximetry and capnography monitoring.
METHODS: PRediction of Opioid-induced respiratory Depression In patients monitored by capnoGraphY (PRODIGY) was a prospective, observational trial of blinded continuous capnography and oximetry conducted at 16 sites in the United States, Europe, and Asia. Vital signs were intermittently monitored per standard of care. A total of 1335 patients receiving parenteral opioids and continuously monitored on the general care floor were included in the analysis. A respiratory depression episode was defined as respiratory rate ≤5 breaths/min (bpm), oxygen saturation ≤85%, or end-tidal carbon dioxide ≤15 or ≥60 mm Hg for ≥3 minutes; apnea episode lasting \u3e30 seconds; or any respiratory opioid-related adverse event. A risk prediction tool was derived using a multivariable logistic regression model of 46 a priori defined risk factors with stepwise selection and was internally validated by bootstrapping.
RESULTS: One or more respiratory depression episodes were detected in 614 (46%) of 1335 general care floor patients (43% male; mean age, 58 ± 14 years) continuously monitored for a median of 24 hours (interquartile range [IQR], 17-26). A multivariable respiratory depression prediction model with area under the curve of 0.740 was developed using 5 independent variables: age ≥60 (in decades), sex, opioid naivety, sleep disorders, and chronic heart failure. The PRODIGY risk prediction tool showed significant separation between patients with and without respiratory depression (P \u3c .001) and an odds ratio of 6.07 (95% confidence interval [CI], 4.44-8.30; P \u3c .001) between the high- and low-risk groups. Compared to patients without respiratory depression episodes, mean hospital length of stay was 3 days longer in patients with ≥1 respiratory depression episode (10.5 ± 10.8 vs 7.7 ± 7.8 days; P \u3c .0001) identified using continuous oximetry and capnography monitoring.
CONCLUSIONS: A PRODIGY risk prediction model, derived from continuous oximetry and capnography, accurately predicts respiratory depression episodes in patients receiving opioids on the general care floor. Implementation of the PRODIGY score to determine the need for continuous monitoring may be a first step to reduce the incidence and consequences of respiratory compromise in patients receiving opioids on the general care floor
The extended H i halo of NGC 4945 as seen by MeerKAT
The State Agency for Research of the Spanish Ministry of Science, Innovation and Universities through the ‘Center of Excellence Severo Ochoa’ awarded to the Instituto de Astrofísica de Andalucía; the Economic Transformation, Industry, Knowledge and Universities Council of the Regional Government of Andalusia and the European Regional Development Fund from the European Union; the South African Radio Astronomy Observatory (SARAO); BMBF Verbundforschung; DFG Sonderforschungsbereich and the European Research Council (ERC).http://mnras.oxfordjournals.orghj2022Physic
Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine
[This corrects the article DOI: 10.1186/s13054-016-1208-6.]
Monoculturalidad en las prácticas pedagógicas en la formación inicial docente en La Araucanía, Chile
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