81 research outputs found
Study of the plutino object (208996) 2003 AZ84 from stellar occultations: size, shape and topographic features
We present results derived from four stellar occultations by the plutino
object (208996) 2003~AZ, detected at January 8, 2011 (single-chord
event), February 3, 2012 (multi-chord), December 2, 2013 (single-chord) and
November 15, 2014 (multi-chord). Our observations rule out an oblate spheroid
solution for 2003~AZ's shape. Instead, assuming hydrostatic equilibrium,
we find that a Jacobi triaxial solution with semi axes ~km % axis ratios and
, can better account for all our occultation observations.
Combining these dimensions with the rotation period of the body (6.75~h) and
the amplitude of its rotation light curve, we derive a density ~g~cm a geometric albedo . A grazing chord
observed during the 2014 occultation reveals a topographic feature along
2003~AZ's limb, that can be interpreted as an abrupt chasm of width
~km and depth ~km or a smooth depression of width ~km
and depth ~km (or an intermediate feature between those two extremes)
The cell biology of vision
Humans possess the remarkable ability to perceive color, shape, and motion, and to differentiate between light intensities varied by over nine orders of magnitude. Phototransduction—the process in which absorbed photons are converted into electrical responses—is the first stage of visual processing, and occurs in the outer segment, the light-sensing organelle of the photoreceptor cell. Studies of genes linked to human inherited blindness have been crucial to understanding the biogenesis of the outer segment and membrane-trafficking of photoreceptors
Submillimetre Source Counts in the Fields of High-Redshift Galaxy Clusters
We present a submillimetre survey of seven high-z galaxy clusters
(0.64<z<1.0) using the Submillimetre Common-User Bolometer Array (SCUBA) at 850
and 450 um. The targets, of similar richness and redshift, are selected from
the Red-sequence Cluster Survey (RCS). We use this sample to investigate the
apparent excess of submillimetre source counts in the direction of cluster
fields compared to blank fields. The sample consists of three galaxy clusters
that exhibit multiple optical arcs due to strong gravitational lensing, and a
control group of four clusters with no apparent strong lensing. A tentative
excess of 2.7-sigma is seen in the number density of submillimetre luminous
galaxies (SMGs) within the lensing cluster fields compared to that in the
control group. Ancillary observations at radio, mid-infrared, optical, and
X-ray wavelengths allow for the identification of counterparts to many of the
SMGs. Utilizing photometric redshifts, we conclude that at least three of the
galaxies within the lensing fields have redshifts consistent with the clusters
and implied infrared luminosities of ~10^12 Lsol. The existence of SMG cluster
members may therefore be boosting source counts in the lensing cluster fields,
which might be an effect of the dynamical state of those clusters. However, we
find that the removal of potential cluster members from the counts analysis
does not entirely eliminate the difference between the cluster samples. We also
investigate possible occurrences of lensing between background SMGs and lower-z
optical galaxies, though further observations are required to make any
conclusive claims. Although the excess counts between the two cluster samples
have not been unambiguously accounted for, these results warrant caution for
interpreting submillimetre source counts in cluster fields and point source
contamination for Sunyaev-Zel'dovich surveys. [Abridged]Comment: 33 pages, 23 figures, 5 tables; accepted for publication in MNRA
Wear and corrosion interactions on titanium in oral environment : literature review
The oral cavity is a complex environment where corrosive substances from dietary, human saliva, and oral biofilms may accumulate in retentive areas of dental implant systems and prostheses promoting corrosion at their surfaces. Additionally, during mastication, micromovements may occur between prosthetic joints causing a relative motion between contacting surfaces, leading to wear. Both processes (wear and corrosion) result in a bio-tribocorrosion system once that occurs in contact with biological tissues and fluids. This review paper is focused on the aspects related to the corrosion and wear behavior of titanium-based structures in the oral environment. Furthermore, the clinical relevance of the oral environment is focused on the harmful effect that acidic substances and biofilms, formed in human saliva, may have on titanium surfaces. In fact, a progressive degradation of titanium by wear and corrosion (tribocorrosion) mechanisms can take place affecting the performance of titanium-based implant and prostheses. Also, the formation of wear debris and metallic ions due to the tribocorrosion phenomena can become toxic for human tissues. This review gathers knowledge from areas like materials sciences, microbiology, and dentistry contributing to a better understanding of bio-tribocorrosion processes in the oral environment.(undefined
Vacuum-cooled liquid nitrogen increases the developmental ability of vitrified-warmed bovine oocytes
HEMATOLOGICAL PARAMETERS AND SEROPREVALENCE OF Ehrlichia canis AND Babesia vogeli IN DOGS
Modelagem da Lagoa da Pampulha: uma ferramenta para avaliar o impacto da bacia hidrográfica na dinâmica do fitoplâncton
Incentivos Extracontratuais e Comportamentos Ex Post no Relacionamento entre Shopping e Lojista
Advances in paediatrics in 2016: current practices and challenges in allergy, autoimmune diseases, cardiology, endocrinology, gastroenterology, infectious diseases, neonatology, nephrology, neurology, nutrition, pulmonology
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