1,245 research outputs found
Phage inducible islands in the gram-positive cocci
The SaPIs are a cohesive subfamily of extremely common phage-inducible chromosomal islands (PICIs) that reside quiescently at specific att sites in the staphylococcal chromosome and are induced by helper phages to excise and replicate. They are usually packaged in small capsids composed of phage virion proteins, giving rise to very high transfer frequencies, which they enhance by interfering with helper phage reproduction. As the SaPIs represent a highly successful biological strategy, with many natural Staphylococcus aureus strains containing two or more, we assumed that similar elements would be widespread in the Gram-positive cocci. On the basis of resemblance to the paradigmatic SaPI genome, we have readily identified large cohesive families of similar elements in the lactococci and pneumococci/streptococci plus a few such elements in Enterococcus faecalis. Based on extensive ortholog analyses, we found that the PICI elements in the four different genera all represent distinct but parallel lineages, suggesting that they represent convergent evolution towards a highly successful lifestyle. We have characterized in depth the enterococcal element, EfCIV583, and have shown that it very closely resembles the SaPIs in functionality as well as in genome organization, setting the stage for expansion of the study of elements of this type. In summary, our findings greatly broaden the PICI family to include elements from at least three genera of cocci
Validation of ERA5-Land temperature and relative humidity on four Peruvian glaciers using on-glacier observations
Weather and climate conditions drive the evolution of tropical glaciers which play an important role as water reservoirs for Peruvian inhabitants in the arid coast and semi-arid Andean region. The scarcity of long-term high-quality observations over Peruvian glaciers has motivated the extensive use of reanalysis data to describe the climatic evolution of these glaciers. However, the representativeness and uncertainties of these reanalysis products over these glaciers are still poorly constrained. This study evaluates the ability of the ERA5-Land reanalysis (ERA5L) to reproduce hourly and monthly 2 m air temperature and relative humidity (T2m and Rh2m, respectively) over several Peruvian glaciers. We compared the ERA5L with data from four on-glacier automatic weather stations (AWS), whose hourly time series were completed with nearby stations, for the period January 2017 to December 2019. Results indicates a better performance of the reanalysis for T2m (r >0.80) than for Rh2m (similar to 0.4<
Delivery actuator for a transcervical sterilization device
The use of delivery systems in the human body for positioning and deploying implants, such as closure devices, dilation balloons, stents, coils and sterilization devices, are gaining more importance to preclude surgical incisions and general anesthesia. The majorities of the non-surgical medical devices are delivered in a low profile into human body form and subsequently require specialized operations for their deployment and release. An analogous procedure for permanent female sterilization is the transcervical approach that does not require either general anesthesia or surgical incision and uses a normal body passage. The objective of this paper is to detail the design, development and verification of an ergonomic actuator for a medical application. In particular, this actuator is designed for the deployment and release of an implant to achieve instant permanent female sterilization via the transcervical approach. This implant is deployed under hysteroscopic visualization and requires a sequence of rotary and linear operations for its deployment and release. More specifically, this manually operated actuator is a hand held device designed to transmit the required forces in a particular sequence to effect both implant deployment and release at a target location. In order to design the actuator and to investigate its mechanical behavior, a three-dimensional (3D) Computer Aided Design (CAD) model was developed and Finite Element Method (FEM) was used for simulations and optimization. Actuator validation was performed following a number of successful bench-top in-air deployments and in-vitro deployments in animal tissue and explanted human uteri. During these deployments it was observed that the actuator applied the required forces to the implant resulting in successful deployment. Initial results suggest that this actuator can be used single handedly during the deployment phase. The ongoing enhancement of this actuator is moving towards “first-in- man” clinical trials
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.This paper presents a morphological study of Sternostoma turdi Zumpt and Till, 1955, (female, male and nymph), Sternostoma loxiae Fain, 1965 (female) and Sternostoma christinae Guevara-Benitez, Lopez-Roman and Ubeda-Ontiveros, 1974 (male)
Estudio morfológico de la hembra, macho y ninfa de Rallinyssus Candistigmus Strandtmann, 1948 (Acarina: Rhinonyssidae), parásito de las fosas nasales de Flica Atra Atra L. granadinas
This paper presents a study of female, male and nymph of Rallinyssus caudistigmus STRANDTMANN, 1948, from the nasal cavities of Fulica atra atra L.Se estudian morfológieamente la hembra, macho y ninfa de Raziínyssus caudístigmus STRANDTMANN, 1948, encontrados en las fosas nasales de la focha común. Fulíca atra atra L, capturada en la provincia de Granada
The M4 Core Project with HST --- I. Overview and First-Epoch
We present an overview of the ongoing Hubble Space Telescope large program
GO-12911. The program is focused on the core of M4, the nearest Galactic
globular cluster, and the observations are designed to constrain the number of
binaries with massive companions (black holes, neutron stars, or white dwarfs)
by measuring the ``wobble'' of the luminous (main-sequence) companion around
the center of mass of the pair, with an astrometric precision of ~50
micro-arcseconds. The high spatial resolution and stable medium-band PSFs of
WFC3/UVIS will make these measurements possible. In this work we describe: (i)
the motivation behind this study, (ii) our observing strategy, (iii) the many
other investigations enabled by this unique data set, and which of those our
team is conducting, and (iv) a preliminary reduction of the first-epoch
data-set collected on October 10, 2012.Comment: 25 pages, 14 figures (9 at low resolution), 3 tables. Published in:
Astronomische Nachrichten, Volume 334, Issue 10, pages 1062-1085, December
2013. http://onlinelibrary.wiley.com/doi/10.1002/asna.201311911/abstrac
M4 Core Project with HST - III. Search for variable stars in the primary field
We present the results of a photometric search for variable stars in the core
of the Galactic globular cluster M4. The input data are a large and
unprecedented set of deep Hubble Space Telescope WFC3 images (large program
GO-12911; 120 orbits allocated), primarily aimed at probing binaries with
massive companions by detecting their astrometric wobbles. Though these data
were not optimised to carry out a time-resolved photometric survey, their
exquisite precision, spatial resolution and dynamic range enabled us to firmly
detect 38 variable stars, of which 20 were previously unpublished. They include
19 cluster-member eclipsing binaries (confirming the large binary fraction of
M4), RR Lyrae, and objects with known X-ray counterparts. We improved and
revised the parameters of some among published variables.Comment: 11 pages, 5 figures, 2 tables. Accepted for publication in MNRA
LEGUS and Halpha-LEGUS Observations of Star Clusters in NGC 4449: Improved Ages and the Fraction of Light in Clusters as a Function of Age
We present a new catalog and results for the cluster system of the starburst
galaxy NGC 4449 based on multi-band imaging observations taken as part of the
LEGUS and Halpha-LEGUS surveys. We improve the spectral energy fitting method
used to estimate cluster ages and find that the results, particularly for older
clusters, are in better agreement with those from spectroscopy. The inclusion
of Halpha measurements, the role of stochasticity for low mass clusters, the
assumptions about reddening, and the choices of SSP model and metallicity all
have important impacts on the age-dating of clusters. A comparison with ages
derived from stellar color-magnitude diagrams for partially resolved clusters
shows reasonable agreement, but large scatter in some cases. The fraction of
light found in clusters relative to the total light (i.e., T_L) in the U, B,
and V filters in 25 different ~kpc-size regions throughout NGC 4449 correlates
with both the specific Region Luminosity, R_L, and the dominant age of the
underlying stellar population in each region. The observed cluster age
distribution is found to decline over time as dN/dt ~ t^g, with g=-0.85+/-0.15,
independent of cluster mass, and is consistent with strong, early cluster
disruption. The mass functions of the clusters can be described by a power law
with dN/dM ~ M^b and b=-1.86+/-0.2, independent of cluster age. The mass and
age distributions are quite resilient to differences in age-dating methods.
There is tentative evidence for a factor of 2-3 enhancement in both the star
and cluster formation rate ~100 - 300 Myr ago, indicating that cluster
formation tracks star formation generally. The enhancement is probably
associated with an earlier interaction event
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