340 research outputs found
Maximal Commutative Subalgebras Invariant for CP-Maps: (Counter-)Examples
We solve, mainly by counterexamples, many natural questions regarding maximal
commutative subalgebras invariant under CP-maps or semigroups of CP-maps on a
von Neumann algebra. In particular, we discuss the structure of the generators
of norm continuous semigroups on B(G) leaving a maximal commutative subalgebra
invariant and show that there exists Markov CP-semigroups on M_d without
invariant maximal commutative subalgebras for any d>2.Comment: After the elemenitation in Version 2 of a false class of examples in
Version 1, we now provide also correct examples for unital CP-maps and Markov
semigroups on M_d for d>2 without invariant masa
The Carina Nebula and Gum 31 molecular complex: II. The distribution of the atomic gas revealed in unprecedented detail
We report high spatial resolution observations of the HI 21cm line in the
Carina Nebula and the Gum 31 region obtained with the Australia Telescope
Compact Array. The observations covered 12 deg centred on , achieving an angular resolution of 35
arcseconds. The HI map revealed complex filamentary structures across a wide
range of velocities. Several "bubbles" are clearly identified in the Carina
Nebula Complex, produced by the impact of the massive star clusters located in
this region. An HI absorption profile obtained towards the strong extragalactic
radio source PMN J1032--5917 showed the distribution of the cold component of
the atomic gas along the Galactic disk, with the Sagittarius-Carina and Perseus
spiral arms clearly distinguishable. Preliminary calculations of the optical
depth and spin temperatures of the cold atomic gas show that the HI line is
opaque ( 2) at several velocities in the Sagittarius-Carina
spiral arm. The spin temperature is K in the regions with the highest
optical depth, although this value might be lower for the saturated components.
The atomic mass budget of Gum 31 is of the total gas mass. HI self
absorption features have molecular counterparts and good spatial correlation
with the regions of cold dust as traced by the infrared maps. We suggest that
in Gum 31 regions of cold temperature and high density are where the atomic to
molecular gas phase transition is likely to be occurring.Comment: 20 pages, 1 table, 16 Figures, Accepted for Publication in the
Monthly Notices of the Royal Astronomical Society Journa
Neutrino masses and mixing parameters in a left-right model with mirror fermions
In this work we consider a left-right model containing mirror fermions with
gauge group SU(3). The model has several free parameters which here we have
calculated by using the recent values for the squared-neutrino mass
differences. Lower bound for the mirror vacuum expectation value helped us to
obtain crude estimations for some of these parameters. Also we estimate the
order of magnitude of the masses of the standard and mirror neutrinos.Comment: 13 pages, version submitted to European Physical Journal
Identificación de las características morfológicas relacionadas con la estabilidad del rendimiento de arroz en dos regiones de Colombia
ALS skeletal muscle shows enhanced TGF-β signaling, fibrosis and induction of fibro/adipogenic progenitor markers
Indexación: Web of Science; Scopus.Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease in which upper and lower motoneurons degenerate leading to muscle wasting, paralysis and eventually death from respiratory failure. Several studies indicate that skeletal muscle contributes to disease progression; however the molecular mechanisms remain elusive. Fibrosis is a common feature in skeletal muscle under chronic damage conditions such as those caused by muscular dystrophies or denervation. However, the exact mechanisms of fibrosis induction and the cellular bases of this pathological response are unknown. We show that extracellular matrix (ECM) components are augmented in skeletal muscles of symptomatic hSOD1G93A mice, a widely used murine model of ALS. These mice also show increased TGF-β1 mRNA levels, total Smad3 protein levels and p-Smad3 positive nuclei. Furthermore, platelet-derived growth factor receptor-α (PDGFRα), Tcf4 and α-smooth muscle actin (α-SMA) levels are augmented in the skeletal muscle of symptomatic hSOD1G93A mice. Additionally, the fibro/adipogenic progenitors (FAPs), which are the main producers of ECM constituents, are also increased in these pathogenic conditions. Therefore, FAPs and ECM components are more abundant in symptomatic stages of the disease than in pre-symptomatic stages. We present evidence that fibrosis observed in skeletal muscle of symptomatic hSOD1G93A mice is accompanied with an induction of TGF-β signaling, and also that FAPs might be involved in triggering a fibrotic response. Co-localization of p-Smad3 positive cells together with PDGFRα was observed in the interstitial cells of skeletal muscles from symptomatic hSOD1G93A mice. Finally, the targeting of pro-fibrotic factors such as TGF-β, CTGF/CCN2 and platelet-derived growth factor (PDGF) signaling pathway might be a suitable therapeutic approach to improve muscle function in several degenerative diseases. © 2017 Gonzalez et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.http://journals.plos.org/plosone/article?id=10.1371/journal.pone.017764
Controlling for contamination in re-sequencing studies with a reproducible web-based phylogenetic approach
Polymorphism discovery is a routine application of next-generation sequencing technology where multiple samples are sent to a service provider for library preparation, subsequent sequencing, and bioinformatic analyses. The decreasing cost and advances in multiplexing approaches have made it possible to analyze hundreds of samples at a reasonable cost. However, because of the manual steps involved in the initial processing of samples and handling of sequencing equipment, cross-contamination remains a significant challenge. It is especially problematic in cases where polymorphism frequencies do not adhere to diploid expectation, for example, heterogeneous tumor samples, organellar genomes, as well as during bacterial and viral sequencing. In these instances, low levels of contamination may be readily mistaken for polymorphisms, leading to false results. Here we describe practical steps designed to reliably detect contamination and uncover its origin, and also provide new, Galaxy-based, readily accessible computational tools and workflows for quality control. All results described in this report can be reproduced interactively on the web as described at http://usegalaxy.org/contamination
Superefficient microcombs at the wafer level
Photonic integrated circuits utilize planar waveguides to process light on a
chip, encompassing functions like generation, routing, modulation, and
detection. Similar to the advancements in the electronics industry, photonics
research is steadily transferring an expanding repertoire of functionalities
onto integrated platforms. The combination of best-in-class materials at the
wafer-level increases versatility and performance, suitable for large-scale
markets, such as datacentre interconnects, lidar for autonomous driving or
consumer health. These applications require mature integration platforms to
sustain the production of millions of devices per year and provide efficient
solutions in terms of power consumption and wavelength multiplicity for
scalability. Chip-scale frequency combs offer massive wavelength
parallelization, holding a transformative potential in photonic system
integration, but efficient solutions have only been reported at the die level.
Here, we demonstrate a silicon nitride technology on a 100 mm wafer that aids
the performance requirements of soliton microcombs in terms of yield, spectral
stability, and power efficiency. Soliton microcombs are reported with an
average conversion efficiency exceeding 50%, featuring 100 lines at 100 GHz
repetition rate. We further illustrate the enabling possibilities of the space
multiplicity, i.e., the large wafer-level redundancy, for establishing new
sensing applications, and show tri-comb interferometry for broadband
phase-sensitive spectroscopy. Combined with heterogeneous integration of
lasers, we envision a proliferation of high-performance photonic systems for
applications in future navigation systems, data centre interconnects, and
ranging
Differential phase reconstruction of microcombs
Measuring microcombs in amplitude and phase provides unique insight into the
nonlinear cavity dynamics but spectral phase measurements are experimentally
challenging. Here, we report a linear heterodyne technique assisted by
electro-optic downconversion that enables differential phase measurement of
such spectra with unprecedented sensitivity (-50 dBm) and bandwidth coverage (>
110 nm in the telecommunications range). We validate the technique with a
series of measurements, including single cavity and photonic molecule
microcombs
Effect of 2.4-d exogenous application on the abscission and fruit growth in sweet orange. var. salustiana.
The effect of 2.4-D applications in full bloom on the abscission and fruit growth process was studied on sweet orange fruit in 20-year-old trees of Citrus sinensis (L.) Osbeck cv. Salustiana with a high flowering level. Abscission was determined on the whole tree and on the leafy inflorescences. Growth variables of the fruit were characterized (diameter, fresh and dry weight). 2.4-D application (20 mg L-1, 3.6 L per tree) increased the growth rate of the fruits and fruits size at maturity, however reduced the number of fruits which kept constant the yield at harvest. Differences between the diameter of the control fruits and the fruits treated with 2.4-D were observed during the early fruitlet development and until day 43 after anthesis. These differences increased with time following a linear relationship. For all the studied variables the diary increase level reaches the maximum by day 53, when the cell expansion of the vesicles starts
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