9,207 research outputs found
Multiwavelength study of the starburst galaxy NGC7714. I: Ultraviolet-Optical spectroscopy
We have studied the physical conditions in the central 300 pc of the
proto-typical starburst galaxy NGC 7714. Our analysis is based on ultraviolet
spectroscopy with the HST+GHRS and ground-based optical observations.The data
are interpreted using evolutionary models optimized for young starburst
regions. The massive stellar population is derived in a self-consistent way
using the continuum and stellar absorption lines in the ultraviolet and the
nebular emission line optical spectrum.
The central starburst has an age of about 4.5 Myr, with little evidence for
an age spread. Wolf-Rayet features at the ultraviolet indicates a stellar
population of 2000 Wolf-Rayet stars. The overall properties of the newly
formed stars are quite similar to those derived, e.g., in 30 Doradus. A
standard Salpeter IMF is consistent with all observational constraints. We find
evidence for spatial structure within the central 300 pc sampled. Therefore it
is unlikely that the nucleus of NGC 7714 hosts a single star cluster exceeding
the properties of other known clusters. Contrary to previous suggestions, we
find no evidence for a nuclear supernova rate that would significantly exceed
the total disk-integrated rate. About one supernova event per century is
predicted.Comment: 19 pages, 9 figures in a tar file. Accepted for publication in ApJ,
1999, March, issue 51
Cost utility of a pharmacistâled minor ailment service compared with usual pharmacist care
Background: A cluster randomised controlled trial (cRCT) performed from July 2018 to March 2019 demonstrated
the clinical impact of a community pharmacist delivered minor ailment service (MAS) compared with usual pharâ
macist care (UC). MAS consisted of a technology-based face-to-face consultation delivered by trained community
pharmacists. The consultation was guided by clinical pathways for assessment and management, and communicaâ
tion systems, collaboratively agreed with general practitioners. MAS pharmacists were trained and provided monthly
practice support by a practice change facilitator. The objective of this study was to assess the cost utility of MAS,
compared to UC.
Methods: Participants recruited were adult patients with symptoms suggestive of a minor ailment condition, from
community pharmacies located in Western Sydney. Patients received MAS (intervention) or UC (control) and were
followed-up by telephone 14-days following consultation with the pharmacist. A cost utility analysis was conducted
alongside the cRCT. Transition probabilities and costs were directly derived from cRCT study data. Utility values were
not available from the cRCT, hence we relied on utility values reported in the published literature which were used to
calculate quality adjusted life years (QALYs), using the area under the curve method. A decision tree model was used
to capture the decision problem, considering a societal perspective and a 14-day time horizon. Deterministic and
probabilistic sensitivity analyses assessed robustness and uncertainty of results, respectively.
Results: Patients (n=894) were recruited from 30 pharmacies and 82% (n=732) responded to follow-up. On averâ
age, MAS was more costly but also more efective (in terms of symptom resolution and QALY gains) compared to UC.
MAS patients (n=524) gained an additional 0.003 QALYs at an incremental cost of 2277 (95% CI $681.49â3811.22) per QALY.
Conclusion: Economic fndings suggest that implementation of MAS within the Australian context is cost efective.
Trial registration Registered with Australian New Zealand Clinical Trials Registry (ANZCTR) and allocated the ACTRN:
ACTRN12618000286246. Registered on 23 February 2018.Consumer Healthcare Products AustraliaAustralian Governmen
AVOCADO: A Virtual Observatory Census to Address Dwarfs Origins
Dwarf galaxies are by far the most abundant of all galaxy types, yet their
properties are still poorly understood -especially due to the observational
challenge that their intrinsic faintness represents. AVOCADO aims at
establishing firm conclusions on their formation and evolution by constructing
a homogeneous, multiwavelength dataset for a statistically significant sample
of several thousand nearby dwarfs (-18 < Mi < -14). Using public data and
Virtual Observatory tools, we have built GALEX+SDSS+2MASS spectral energy
distributions that are fitted by a library of single stellar population models.
Star formation rates, stellar masses, ages and metallicities are further
complemented with structural parameters that can be used to classify them
morphologically. This unique dataset, coupled with a detailed characterization
of each dwar's environment, allows for a fully comprehensive investigation of
their origins and to track the (potential) evolutionary paths between the
different dwarf types.Comment: 4 pages, 1 figure. To appear in the proceedings of IAU Symposium 277,
"Tracing the Ancestry of Galaxies on the Land of our Ancestors", Carignan,
Freeman, and Combes, ed
Polyploidy in the Olive Complex (Olea europaea): Evidence from Flow Cytometry and Nuclear Microsatellite Analyses
Background Phylogenetic and phylogeographic investigations have been previously performed to study the evolution of the olive tree complex (Olea europaea). A particularly high genomic diversity has been found in north-west Africa. However, to date no exhaustive study has been addressed to infer putative polyploidization events and their evolutionary significance in the diversification of the olive tree and its relatives. Methods Representatives of the six olive subspecies were investigated using (a) flow cytometry to estimate genome content, and (b) six highly variable nuclear microsatellites to assess the presence of multiple alleles at co-dominant loci. In addition, nine individuals from a controlled cross between two individuals of O. europaea subsp. maroccana were characterized with microsatellites to check for chromosome inheritance. Key Results Based on flow cytometry and genetic analyses, strong evidence for polyploidy was obtained in subspp. cerasiformis (tetraploid) and maroccana (hexaploid), whereas the other subspecies appeared to be diploids. Agreement between flow cytometry and genetic analyses gives an alternative approach to chromosome counting to determine ploidy level of trees. Lastly, abnormalities in chromosomes inheritance leading to aneuploid formation were revealed using microsatellite analyses in the offspring from the controlled cross in subsp. maroccana. Conclusions This study constitutes the first report for multiple polyploidy in olive tree relatives. Formation of tetraploids and hexaploids may have played a major role in the diversification of the olive complex in north-west Africa. The fact that polyploidy is found in narrow endemic subspecies from Madeira (subsp. cerasiformis) and the Agadir Mountains (subsp. maroccana) suggests that polyploidization has been favoured to overcome inbreeding depression. Lastly, based on previous phylogenetic analyses, we hypothesize that subsp. cerasiformis resulted from hybridization between ancestors of subspp. guanchica and europae
Can the Recording of Motor Potentials Evoked by Transcranial Magnetic Stimulation Be Optimized?
LINER/H II "Transition" Nuclei and the Nature of NGC 4569
Motivated by the discovery of young, massive stars in the nuclei of some
LINER/H II ``transition'' nuclei such as NGC 4569, we have computed
photoionization models to determine whether some of these objects may be
powered solely by young star clusters rather than by accretion-powered active
nuclei. The models were calculated with the photoionization code CLOUDY, using
evolving starburst continua generated by the the STARBURST99 code of Leitherer
et al. (1999). We find that the models are able to reproduce the emission-line
spectra of transition nuclei, but only for instantaneous bursts of solar or
higher metallicity, and only for ages of ~3-5 Myr, the period when the
extreme-ultraviolet continuum is dominated by emission from Wolf-Rayet stars.
For clusters younger than 3 Myr or older than 6 Myr, and for models with a
constant star-formation rate, the softer ionizing continuum results in an
emission spectrum more typical of H II regions. This model predicts that
Wolf-Rayet emission features should appear in the spectra of transition nuclei.
While such features have not generally been detected to date, they could be
revealed in observations having higher spatial resolution. Demographic
arguments suggest that this starburst model may not apply to the majority of
transition nuclei, particularly those in early-type host galaxies, but it could
account for some members of the transition class in hosts of type Sa and later.
The starburst models during the Wolf-Rayet-dominated phase can also reproduce
the narrow-line spectra of some LINERs, but only under conditions of
above-solar metallicity and only if high-density gas is present (n_e >~ 10^5
cm^{-3}). This scenario could be applicable to some ``Type 2'' LINERs which do
not show any clear signs of nonstellar activity.Comment: To appear in PASP. 22 pages, includes 9 figures, uses AASTeX v5.
The Nature of LINERs
We present -band (m) spectroscopy of a sample of nine
galaxies showing some degree of LINER activity (classical LINERs, weak-[O {\sc
i}] LINERs and transition objects), together with -band spectroscopy for
some of them. A careful subtraction of the stellar continuum allows us to
obtain reliable [Fe {\sc ii}]m/Pa line ratios. We conclude
that different types of LINERs (i.e., photoionized by a stellar continuum or by
an AGN) cannot be easily distinguished based solely on the [Fe {\sc ii}]m/Pa line ratio.
The emission line properties of many LINERs can be explained in terms of an
aging starburst. The optical line ratios of these LINERs are reproduced by a
model with a metal-rich H {\sc ii} region component photoionized with a single
stellar temperature K, plus a supernova remnant (SNR) component.
The [Fe {\sc ii}] line is predominantly excited by shocks produced by SNRs in
starbursts and starburst-dominated LINERs, while Pa tracks H {\sc ii}
regions ionized by massive young stars. The contribution from SNRs to the
overall emission line spectrum is constrained by the [Fe {\sc ii}]m/Pa line ratio. Although our models for aging starbursts are
constrained only by these infrared lines, they consistently explain the optical
spectra of the galaxies also.
The LINER-starburst connection is tested by predicting the time dependence of
the ratio of the ionizing luminosity () to the supernova rate
(SNr), /(SNr). We predict the relative number of starbursts to
starburst-dominated LINERs (aging starbursts) and show that it is in
approximate agreement with survey findings for nearby galaxies.Comment: Accepted in ApJ (19 pages, 8 figures, uses emulateapj.sty
Pneumocystis primary infection in non-immunosuppressed infants in Lima, Peru
Objectives:
To provide original data on Pneumocystis primary infection in non-immunosuppressed infants from Peru. /
Methods:
A cross sectional study was performed. Infants less than seven months old, without any underlying medical conditions attending the âwell babyâ outpatient clinic at one hospital in Lima, Peru were prospectively enrolled during a 15-month period from November 2016 to February 2018. All had a nasopharyngeal aspirate (NPA) for detection of P. jirovecii DNA using a PCR assay, regardless of respiratory symptoms. P. jirovecii DNA detection was considered to represent pulmonary colonization contemporaneous with Pneumocystis primary infection. Associations between infantsâ clinical and demographic characteristics and results of P. jirovecii DNA detection were analyzed. /
Results:
P. jirovecii DNA was detected in 45 of 146 infants (30.8%) and detection was not associated with concurrent respiratory symptoms in 40 of 45 infants. Infants with P. jirovecii had a lower mean age when compared to infants not colonized (p <0.05). The highest frequency of P. jirovecii was observed in 2-3-month-old infants (p < 0.01) and in the cooler winter and spring seasons (p <0.01). Multivariable analysis showed that infants living in a home with †1 bedroom were more likely to be colonized; Odds Ratio =3.03 (95%CI 1.31-7.00; p =0.01). /
Conclusion:
Pneumocystis primary infection in this single site in Lima, Peru, was most frequently observed in 2-3-month-old infants, in winter and spring seasons, and with higher detection rates being associated with household conditions favoring close inter-individual contacts and potential transmission of P. jirovecii
Synthetic spectra of H Balmer and HeI absorption lines. II: Evolutionary synthesis models for starburst and post-starburst galaxies
We present evolutionary stellar population synthesis models to predict the
spectrum of a single-metallicity stellar population, with a spectral sampling
of 0.3 A in five spectral regions between 3700 and 5000 A. The models, which
are optimized for galaxies with active star formation, synthesize the profiles
of the hydrogen Balmer series (Hb, Hg, Hd, H8, H9, H10, H11, H12 and H13) and
the neutral helium absorption lines (HeI 4922, HeI 4471, HeI 4388, HeI 4144,
HeI 4121, HeI 4026, HeI 4009 and HeI 3819) for a burst with an age ranging from
1 to 1000 Myr, and different assumptions about the stellar initial mass
function. Continuous star formation models lasting for 1 Gyr are also
presented. The input stellar library includes NLTE absorption profiles for
stars hotter than 25000 K and LTE profiles for lower temperatures. The
temperature and gravity coverage is 4000 K <Teff< 50000 K and 0.0< log g$< 5.0,
respectively.
The models can be used to date starburst and post-starburst galaxies until 1
Gyr. They have been tested on data for clusters in the LMC, the super-star
cluster B in the starburst galaxy NGC 1569, the nucleus of the dwarf elliptical
NGC 205 and a luminous "E+A" galaxy. The full data set is available for
retrieval at http://www.iaa.es/ae/e2.html and at
http://www.stsci.edu/science/starburst/, or on request from the authors at
[email protected]: To be published in ApJS. 48 pages and 20 figure
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