6,004 research outputs found
MORFOGÉNESIS DE TRYPANOSOMA CRUZI: FACTORES RELEVANTES PARA LA DIFERENCIACIÓN IN VITRO
En este artículo nosotros revisamos el estado actual de la morfogénesis de Trypanosoma cruzi in vivo e in vitro examinando los siguientes aspectos a) la definición de estadio del parásito y el concepto de competencia, b) epimastigogénesis y metaciclogénesis en el vector e inducida in vitro, c) amastigogénesis y tripomastigogénesis extra e intracelular. Nosotros enfatizamos el papel que juegan algunos factores que disparan los procesos de diferenciación en condiciones axénicas. Proponemos como hipótesis que en los hospedadores vertebrado e invertebrado, la secuencia de eventos morfológicos son equivalentes y solo difiere la velocidad en que ocurren en función de la temperatura microambiental
Discovery of a cluster of galaxies behind the Milky Way: X-ray and optical observations
We report the discovery of Cl 2334+48, a rich cluster of galaxies in the Zone
of Avoidance, identified in public images from the XMM-Newton archive. We
present the main properties of this cluster using the XMM-Newton X-ray data,
along with new optical spectroscopic and photometric observations. Cl 2334+48
is located at z = 0.271 +/- 0.001, as derived from the optical spectrum of the
brightest member galaxy. Such redshift agrees with a determination from the
X-ray spectrum (z = 0.263 (+0.012/-0.010)), in which an intense emission line
is matched to the rest wavelength of the Fe Kalpha complex. Its intracluster
medium has a plasma temperature of 4.92 (+0.50/-0.48) keV, sub-solar abundance
(0.38 +/- 0.12 Zsun), and a bolometric luminosity of 3.2 x 10^44 erg/s. A
density contrast delta = 2500 is obtained in a radius of 0.5 Mpc/h70, and the
corresponding enclosed mass is 1.5 x 10^14 Msun. Optical images show an
enhancement of g'-i' > 2.5 galaxies around the central galaxy, as expected if
these were cluster members. The central object is a luminous E-type galaxy,
which is displaced ~ 40 kpc/h70 from the cluster X-ray center. In addition, it
has a neighbouring arc-like feature (~ 22" or 90 kpc/h70 from it), probably due
to strong gravitational lensing. The discovery of Cl 2334+48 emphasises the
remarkable capability of the XMM-Newton to reveal new clusters of galaxies in
the Zone of Avoidance.Comment: 9 pages, 11 figures, Accepted for publication in A&A (on July 12,
2006
Translucency parameter of conventional restorative glass-ionomer cements.
OBJECTIVE: To evaluate the translucency parameter (TP) and contrast ratio (CR) of different conventional restorative glass-ionomer cements (GICs). MATERIALS AND METHODS: Eighteen brands of GICs were evaluated. Five disks of each material were made following ISO 9917-1. The luminous reflectance and Central Bureau of the International Commission on Illumination parameters of disks were evaluated using a colorimeter, against backings of white and black, to obtain the translucent parameter and contrast ratio of different brands of glass-ionomer cements. The correlation between translucency parameter and contrast ratio was assessed with the Pearson correlation test. The translucent and contrast ratio parameters values were submitted to the one-way ANOVA and Tukey test for multiple comparisons (p < 0.05). RESULTS: There was a strong inverse relationship between CR and TP (r2 = 0.94, p < 0.001). The contrast ratio decreased as translucency increased. There were significant differences in TP and CR among brands (p < 0.001). CONLUSIONS: GICs exhibit different translucency and contrast ratio behavior. Some brands of GICs presented very low TP and this condition would be unacceptable for areas with esthetic demands. In addition, TP and CR showed a strong linear relationship. CLINICAL SIGNIFICANCE: The results found in this study demonstrated that the knowledge of the translucency and CR of different conventional restorative GICs is important in order to guide clinicians in the selection of restorative GICs for anterior teeth
NoSOCS in SDSS. II. Mass Calibration of Low Redshift Galaxy Clusters with Optical and X-ray Properties
We use SDSS data to investigate the scaling relations of 127 NoSOCS and 56
CIRS galaxy clusters at low redshift (). We show that richness and
both optical and X-ray luminosities are reliable mass proxies. The scatter in
mass at fixed observable is 40%, depending on the aperture, sample and
observable considered. For example, for the massive CIRS systems
= 0.33 0.05 and = 0.48
0.06. For the full sample = 0.43 0.03 and
= 0.56 0.06. We estimate substructure using two and
three dimensional optical data, verifying that substructure has no significant
effect on the cluster scaling relations (intercepts and slopes), independent of
which substructure test we use. For a subset of twenty-one clusters, we
estimate masses from the M-T relation using temperature measures from BAX.
The scaling relations derived from the optical and X-ray masses are indeed very
similar, indicating that our method consistently estimates the cluster mass and
yields equivalent results regardless of the wavelength from which we measure
mass. For massive systems, we represent the mass-richness relation by a
function with the form , with
M being expressed in units of 10 M. Using the virial
mass, for CIRS clusters, we find A = (1.39 0.07) and B = (1.00
0.11). The relations based on the virial mass have a scatter of
= 0.37 0.05, while = 0.77
0.22 for the caustic mass and = 0.34 0.08
for the temperature based mass (abridged).Comment: 27 pages, 22 figures, 12 tables, Accepted to MNRA
Stars and dark matter in the spiral gravitational lens 2237+0305
We construct a mass model for the spiral lens galaxy 2237+0305, at redshift
z_l=0.04, based on gravitational-lensing constraints, HI rotation, and new
stellar-kinematic information, based on data taken with the ESI spectrograph on
the 10m Keck-II Telescope. High resolution rotation curves and velocity
dispersion profiles along two perpendicular directions, close to the major and
minor axes of the lens galaxy, were obtained by fitting the Mgb-Fe absorption
line region. The stellar rotation curve rises slowly and flattens at r~1.5"
(~1.1 kpc). The velocity dispersion profile is approximately flat. A
combination of photometric, kinematic and lensing information is used to
construct a mass model for the four major mass components of the system -- the
dark matter halo, disc, bulge, and bar. The best-fitting solution has a dark
matter halo with a logarithmic inner density slope of gamma=0.9+/-0.3 for
rho_DM propto r^-gamma, a bulge with M/L_B=6.6+/-0.3 Upsilon_odot, and a disc
with M/L_B =1.2+/-0.3 Upsilon_odot, in agreement with measurements of late-type
spirals. The bulge dominates support in the inner regions where the multiple
images are located and is therefore tightly constrained by the observations.
The disc is sub-maximal and contributes 45+/-11 per cent of the rotational
support of the galaxy at 2.2r_d. The halo mass is (2.0+/-0.6) x 10^12 M_odot,
and the stellar to virial mass ratio is 7.0+/-2.3 per cent, consistent with
typical galaxies of the same mass.Comment: 14 pages, 6 figures, MNRAS, in pres
Sensitivity and Insensitivity of Galaxy Cluster Surveys to New Physics
We study the implications and limitations of galaxy cluster surveys for
constraining models of particle physics and gravity beyond the Standard Model.
Flux limited cluster counts probe the history of large scale structure
formation in the universe, and as such provide useful constraints on
cosmological parameters. As a result of uncertainties in some aspects of
cluster dynamics, cluster surveys are currently more useful for analyzing
physics that would affect the formation of structure than physics that would
modify the appearance of clusters. As an example we consider the Lambda-CDM
cosmology and dimming mechanisms, such as photon-axion mixing.Comment: 24 pages, 8 eps figures. References added, discussion of scatter in
relations between cluster observables lengthene
Ovarian activity, metabolic and physiological parameters of Canindé goats submitted to short-term supplementation with licuri oil.
This study aimed to evaluate the estrous behavior, ovarian activity, feed intake, metabolic and physiological parameters of Canind ?e goats supplemented for nine days with Licuri oil (Syagrus coronata). Thirty-six adult fe- male goats were distributed randomly into two groups: control group (n = 18) without Licuri oil and the oil group (n = 18) receiving a supplement containing 3% Licuri oil. The short-term food supplementation was associated with an estrus synchronization protocol. The number of ovulations and follicle diameter were eval- uated by ultrasonography. Dry matter intake (DMI) and nutrient intake, water ingestion, and physiological parameters such as rectal temperature (RT), respiratory rate (RR), heart rate (HR), and serum concentrations of cholesterol and non-esterified fatty acids (NEFA) were also determined. As concern statistical analysis, ANOVA followed by Fisher?s LSD was used and the differences were considered significant when P < 0.05. The control group showed higher HR and RR in the afternoon shift compared to the Oil group. The Oil group showed lower DMI but higher ether extract intake, and serum cholesterol and NEFA concentration than control group. Treatments did not affect estrus response and ovulation rate, but the Licuri oil increased the number of small follicles. The supplementation of Licuri oil improved thermal comfort during the dry season and a marginal increase in the ovarian activity was observed
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