9,353 research outputs found
Evidence for a Massive Neutron Star from a Radial-Velocity Study of the Companion to the Black Widow Pulsar PSR B1957+20
The most massive neutron stars constrain the behavior of ultra-dense matter,
with larger masses possible only for increasingly stiff equations of state.
Here, we present evidence that the black widow pulsar, PSR B1957+20, has a high
mass. We took spectra of its strongly irradiated companion and found an
observed radial-velocity amplitude of K_obs=324+/-3 km/s. Correcting this for
the fact that, due to the irradiation, the center of light lies inward relative
to the center of mass, we infer a true radial-velocity amplitude of K_2=353+/-4
km/s and a mass ratio q=M_PSR/M_2=69.2+/-0.8. Combined with the inclination
i=65+/-2 deg inferred from models of the lightcurve, our best-fit pulsar mass
is M_PSR=2.40+/-0.12 M_sun. We discuss possible systematic uncertainties, in
particular in the lightcurve modeling. Taking an upper limit of i<85 deg based
on the absence of radio eclipses at high frequency, combined with a
conservative lower-limit to the motion of the center of mass, K_2>343 km/s
(q>67.3), we infer a lower limit to the pulsar mass of M_PSR>1.66 M_sun.Comment: 7 pages, 3 figures, 1 table, accepted for publication in ApJ;
revision includes more detail on the spectral classification and discussion
of other recent high neutron-star masse
Young Radio Pulsars in Galactic Globular Clusters
Currently three isolated radio pulsars and one binary radio pulsar with no
evidence of any previous recycling are known in 97 surveyed Galactic globular
clusters. As pointed out by Lyne et al., the presence of these pulsars cannot
be explained by core-collapse supernovae, as is commonly assumed for their
counterparts in the Galactic disk. We apply a Bayesian analysis to the results
from surveys for radio pulsars in globular clusters and find the number of
potentially observable non-recycled radio pulsars present in all clusters to be
< 3600. Accounting for beaming and retention considerations, the implied birth
rate for any formation scenario for all 97 clusters is < 0.25 pulsars per
century assuming a Maxwellian distribution of velocities with a dispersion of
10 km s^{-1}. The implied birth rates for higher velocity dispersions are
substantially higher than inferred for such pulsars in the Galactic disk. This
suggests that the velocity dispersion of young pulsars in globular clusters is
significantly lower than those of disk pulsars. These numbers may be
substantial overestimates due to the fact that the currently known sample of
young pulsars is observed only in metal-rich clusters. We propose that young
pulsars may only be formed in globular clusters with metallicities with
log[Fe/H] > -0.6. In this case, the potentially observable population of such
young pulsars is 447^{+1420}_{-399} (the error bars give the 95% confidence
interval) and their birth rate is 0.012^{+0.037}_{-0.010} pulsars per century.
The mostly likely creation scenario to explain these pulsars is the electron
capture supernova of a OMgNe white dwarf.Comment: 13 Pages, 6 Figures, 4 Tables, to appear in Ap
The Arecibo 430-MHz Intermediate Galactic Latitude Survey: Discovery of Nine Radio Pulsars
We have used the Arecibo Radio Telescope to search for millisecond pulsars in
two intermediate Galactic latitude regions (7 deg < | b | < 20 deg) accessible
to this telescope. For these latitudes the useful millisecond pulsar search
volume achieved by Arecibo's 430-MHz beam is predicted to be maximal. Searching
a total of 130 square degrees, we have discovered nine new pulsars and detected
four previously known objects. We compare the results of this survey with those
of other 430-MHz surveys carried out at Arecibo and of an intermediate latitude
survey made at Parkes that included part of our search area; the latter
independently found two of the nine pulsars we have discovered.
At least six of our discoveries are isolated pulsars with ages between 5 and
300 Myr; one of these, PSR J1819+1305, exhibits very marked and periodic
nulling. We have also found a recycled pulsar, PSR J2016+1948. With a
rotational period of 65 ms, this is a member of a binary system with a 635-day
orbital period. We discuss some of the the properties of this system in detail,
and indicate its potential to provide a test of the Strong Equivalence
Principle. This pulsar and PSR J0407+16, a similar system now being timed at
Arecibo, are by far the best systems known for such a test.Comment: Accepted for publication in ApJ Referee format: 22 pages, 7 figure
Oral health-related quality of life in portuguese pre-school children: a cross-sectional study
Purpose To study Oral Health related Quality of Life (OHRQoL) of pre-school children and its associated factors.
Methods Cross-sectional study with sample data collected through an on-line questionnaire to a non-probabilistic sample.
The questionnaire included the Portuguese version of the Early Childhood Oral Health Impact Scale (ECOHIS) and questions
about sociodemographic characteristics, oral health behaviours, and reported oral health of the child. Data analyses included
descriptive statistics, Mann–Whitney and Kruskal–Wallis tests and Linear regression (α=0.05).
Results The sample consisted of 1475 parents of pre-school children (3–5 years-old), residing in Portugal. The mean ECOHIS
total score was 1.5 (sd=3.4). In the bivariate analysis the child’s age, starting toothbrushing after one year of age, frequent
intake of sugary food and drinks, previous appointment with an oral health professional, all reported of oral health problems,
and a negative perception of oral health were negatively associated with OHRQoL (p<0,05). In the regression model the
factors that most contributed to a worse quality of life were dental caries and abscess, contributing to an ECOHIS average
increase of 2.56 and 3.34, respectively.
Conclusions The studied population presented a good OHRQoL, with the item related to pain being the most relevant for
the ECOHIS score. Worst OHRQoL was found in older children, whose parents negatively rated the children's oral health
and with reported dental caries, trauma, and abscess.info:eu-repo/semantics/publishedVersio
The role of ionic liquids in the pharmaceutical field: an overview of relevant applications
Solubility, bioavailability, permeation, polymorphism, and stability concerns associated to solid-state pharmaceuticals demand for effective solutions. To overcome some of these drawbacks, ionic liquids (ILs) have been investigated as solvents, reagents, and anti-solvents in the synthesis and crystallization of active pharmaceutical ingredients (APIs), as solvents, co-solvents and emulsifiers in drug formulations, as pharmaceuticals (API-ILs) aiming liquid therapeutics, and in the development and/or improvement of drug-delivery-based systems. The present review focuses on the use of ILs in the pharmaceutical field, covering their multiple applications from pharmaceutical synthesis to drug delivery. The most relevant research conducted up to date is presented and discussed, together with a critical analysis of the most significant IL-based strategies in order to improve the performance of therapeutics and drug delivery systems.publishe
Extraction of high value triterpenic acids from eucalyptus globulus biomass using hydrophobic deep eutectic solvents
Triterpenic acids (TTAs), known for their promising biological properties, can be found in different biomass sources and related by-products, such as Eucalyptus globulus bark, and have been extracted using organic volatile solvents such as dichloromethane. Recently, deep eutectic solvents (DES) have been identified as promising alternatives for the extraction of value-added compounds from biomass. In the present work, several hydrophobic DES were tested for the extraction of TTAs from E. globulus bark. Initial solubility studies revealed that DES based on menthol and thymol as the most promising solvents for these compounds given the highest solubilities obtained for ursolic acid (UA) at temperatures ranging from room temperature up to 90 °C. Accordingly, an eutectic mixture of menthol:thymol (1:2) was confirmed as the best candidate for the TTAs extraction from E. globulus outer bark, leading to extraction yields (weight of TTA per weight of biomass) at room temperature of 1.8 wt% for ursolic acid, 0.84 wt% for oleanolic acid and 0.30 wt% for betulinic acid. These values are significantly higher than those obtained with conventional organic solvents under similar conditions. The results obtained using these DES are promising for the recovery of TTAs for nutraceutical and pharmacological applications, while reinforcing the potential of DES as promising solvents to be applied in biorefinery processes.publishe
Proteínas de feijão caupi [Vigna unguiculata (L.) Walp]: caracterização e aplicação nutricional.
Utilização e valor protéico; Proteínas de reserva; Protéinas tóxicas.bitstream/item/35890/1/Doc44.pd
Co‐existing monophasic teratoma and uterine adenocarcinoma in a female dog
Ovarian teratomas are occasionally reported in dogs; the rarest type is the monophasic teratoma,composed of tissues originating from only one germ layer. Canine endometrial adenocarcinomas are also rare in dogs and mainly affect geriatric females.
This report describes case of co-existing ovarian teratoma and uterine adenocarcinoma in a 10-year old nulliparous female Boxer presented with lethargy, anorexia and purulent vaginal discharge.
Abdominal ultrasonography evidenced pyometra and a mass in the left ovary. This was composed of
a uniform whitish tissue with multiple cystic structures. The histology revealed an atrophy of the ovarian parenchyma, compressed by a proliferation of well-differentiated nervous tissue staining positively to vimentin, S100 and neuronal specific enolase (NSE), and negatively to keratin and inhibin. The left uterine horn, whose diameter was markedly increased, showed foci of endometrial cellular atypia, evident nucleoli and mitoses, at light microscopy.
To our best knowledge, this is the first report of a coexisting ovarian monophasic teratoma and
endometrial adenocarcinoma, two rare reproductive neoplasia in dogs
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