16,532 research outputs found
Identification of a novel sequence motif recognised by the ankyrin-repeat domain of zDHHC17/13 S-acyl-transferases
S-acylation is a major post-translational modification affecting several cellular processes and being particularly important for neuronal functions. This modification is catalysed by a family of transmembrane S-acyl-transferases that contain a conserved zinc-finger DHHC (zDHHC) domain. Typically, eukaryote genomes encode for 7-24 distinct zDHHC enzymes, with 2 members also harbouring an ankyrin-repeat (AR) domain at their cytosolic N-terminus. The AR domain of zDHHC enzymes is predicted to engage in numerous interactions, and facilitates both substrate recruitment and S-acylation-independent functions; however, the sequence/structural features recognised by this module remain unknown. The two mammalian AR-containing S-acyltransferases are the Golgi-localised zDHHC17 and zDHHC13, also known as Huntingtin-interacting proteins 14 and 14-like, respectively; these are highly expressed in brain, and their loss in mice leads to neuropathological deficits that are reminiscent of Huntington disease. Here, we report that zDHHC17 and zDHHC13 recognise via their AR domain, evolutionary conserved and closely related sequences of a [VIAP][VIT]xxQP consensus in SNAP25, SNAP23, Cysteine-String Protein, Huntingtin, Cytoplasmic Linker Protein 3 and Microtubule Associated Protein 6. This novel AR-binding sequence motif is found in regions predicted to be unstructured, and is present in a number of zDHHC17 substrates and zDHHC17/13-interacting S-acylated proteins. This is the first study to identify a motif recognised by AR-containing zDHHCs
Ultra Low-Power Analog Median Filters
The design and implementation of three analog median filter topologies, whose transistors operate in the deep weak-inversion region, is described. The first topology is a differential pairs array, in which drain currents are driven into two nodes in a differential fashion, while the second topology is based on a wide range OTA, which is used to maximize the dynamic range. Finally, the third topology uses three range-extended OTAs. The proposed weak-inversion filters were designed and fabricated in ON Semiconductor 0.5 micrometer technology through MOSIS. Experimental results of three-input fabricated prototypes for all three topologies are show, where power consumptions of 90nW in the first case, and 270nW in the other two cases can be noticed. A dual power supply +/-1.5 Volts were used
Study of star-forming galaxies in SDSS up to redshift 0.4: I. Metallicity evolution
The chemical composition of the gas in galaxies versus cosmic time provides a
very important tool for understanding galaxy evolution. Although there are many
studies at high redshift, they are rather scarce at lower redshifts. However,
low redshift studies can provide important clues about the evolution of
galaxies, furnishing the required link between local and high redshift
universe. In this work we focus on the metallicity of the gas of star-forming
galaxies at low redshift, looking for signs of chemical evolution.
To analyze the metallicity contents star-forming galaxies of similar
luminosities and masses at different redshifts. With this purpose, we present a
study of the metallicity of relatively massive (log(M_star/M_sun)>10.5) star
forming galaxies from SDSS--DR5 (Sloan Digital Sky Survey--Data Release 5),
using different redshift intervals from 0.04 to 0.4.
We used data processed with the STARLIGHT spectral synthesis code, correcting
the fluxes for dust extinction, estimating metallicities using the R_23 method,
and segregating the samples with respect to the value of the
[NII]6583/[OII]3727 line ratio in order to break the R_23 degeneracy selecting
the upper branch. We analyze the luminosity and mass-metallicity relations, and
the effect of the Sloan fiber diameter looking for possible biases.
By dividing our redshift samples in intervals of similar magnitude and
comparing them, significant signs of metallicity evolution are found.
Metallicity correlates inversely with redshift: from redshift 0 to 0.4 a
decrement of ~0.1 dex in 12+log(O/H) is found.Comment: 11 pages, 9 figures, Accepted for publication in A&
XMM-Newton and Deep Optical Observations of the OTELO fields: the Groth-Westphal Strip
OTELO (OSIRIS Tunable Emission Line Object Survey) will be carried out with
the OSIRIS instrument at the 10 m GTC telescope at La Palma, and is aimed to be
the deepest and richest survey of emission line objects to date. The deep
narrow-band optical data from OSIRIS will be complemented by means of
additional observations that include: (i) an exploratory broad-band survey that
is already being carried out in the optical domain, (ii) FIR and sub-mm
observations to be carried with the Herschel space telescope and the GTM, and
(iii) deep X-Ray observations from XMM-Newton and Chandra.Here we present a
preliminary analysis of public EPIC data of one of the OTELO targets,the
Groth-Westphal strip, gathered from the XMM-Newton Science Archive (XSA). EPIC
images are combined with optical BVRI data from our broadband survey carried
out with the 4.2m WHT at La Palma. Distance-independent diagnostics (involving
X/O ratio, hardness ratios, B/T ratio) are tested.Comment: 2 pages, 2 figures, uses graphicx package. To appear in proceedings
of "The X-Ray Universe 2005", San Lorenzo del Escorial, Spain, September
26-30, 200
Mechanical detection of carbon nanotube resonator vibrations
Bending-mode vibrations of carbon nanotube resonator devices were
mechanically detected in air at atmospheric pressure by means of a novel
scanning force microscopy method. The fundamental and higher order bending
eigenmodes were imaged at up to 3.1GHz with sub-nanometer resolution in
vibration amplitude. The resonance frequency and the eigenmode shape of
multi-wall nanotubes are consistent with the elastic beam theory for a doubly
clamped beam. For single-wall nanotubes, however, resonance frequencies are
significantly shifted, which is attributed to fabrication generating, for
example, slack. The effect of slack is studied by pulling down the tube with
the tip, which drastically reduces the resonance frequency
The Low Redshift survey at Calar Alto (LoRCA)
The Baryon Acoustic Oscillation (BAO) feature in the power spectrum of
galaxies provides a standard ruler to measure the accelerated expansion of the
Universe. To extract all available information about dark energy, it is
necessary to measure a standard ruler in the local, z<0.2, universe where dark
energy dominates most the energy density of the Universe. Though the volume
available in the local universe is limited, it is just big enough to measure
accurately the long 100 Mpc/h wave-mode of the BAO. Using cosmological N-body
simulations and approximate methods based on Lagrangian perturbation theory, we
construct a suite of a thousand light-cones to evaluate the precision at which
one can measure the BAO standard ruler in the local universe. We find that
using the most massive galaxies on the full sky (34,000 sq. deg.), i.e. a
K(2MASS)<14 magnitude-limited sample, one can measure the BAO scale up to a
precision of 4\% and 1.2\% using reconstruction). We also find that such a
survey would help to detect the dynamics of dark energy.Therefore, we propose a
3-year long observational project, named the Low Redshift survey at Calar Alto
(LoRCA), to observe spectroscopically about 200,000 galaxies in the northern
sky to contribute to the construction of aforementioned galaxy sample. The
suite of light-cones is made available to the public.Comment: 15 pages. Accepted in MNRAS. Please visit our website:
http://lorca-survey.ft.uam.es
Fractal dimension of interstellar clouds: opacity and noise effects
There exists observational evidence that the interstellar medium has a
fractal structure in a wide range of spatial scales. The measurement of the
fractal dimension (Df) of interstellar clouds is a simple way to characterize
this fractal structure, but several factors, both intrinsic to the clouds and
to the observations, may contribute to affect the values obtained. In this work
we study the effects that opacity and noise have on the determination of Df. We
focus on two different fractal dimension estimators: the perimeter-area based
dimension (Dper) and the mass-size dimension (Dm). We first use simulated
fractal clouds to show that opacity does not affect the estimation of Dper.
However, Dm tends to increase as opacity increases and this estimator fails
when applied to optically thick regions. In addition, very noisy maps can
seriously affect the estimation of both Dper and Dm, decreasing the final
estimation of Df. We apply these methods to emission maps of Ophiuchus, Perseus
and Orion molecular clouds in different molecular lines and we obtain that the
fractal dimension is always in the range 2.6 < Df < 2.8 for these regions.
These results support the idea of a relatively high (> 2.3) average fractal
dimension for the interstellar medium, as traced by different chemical species.Comment: 17 pages including 6 figures and 1 table. Accepted for publication in
Ap
Relationship between the gut microbiome and osteoarthritis pain: Review of the literature
Background: Osteoarthritis (OA) is the most common form of chronic pain in Europe (34%), representing a great economic and social cost to society. There are studies that suggest an intestineâbrainâarticulation axis and hint at the existence of low-grade intestinal inflammation in OA, which would be related to an alteration of the microbiota and to the impairment of the epithelial barrier, with leakage of the microbial components. Purpose: The purpose of this study was to review the association between gut microbiome and pain in the OA population through a review of the literature. Methods: A literature search was conducted to identify all available studies on the association between the gut microbiome and pain in the OA population, with no publication date limit until September 2020 and no language limit, in the MEDLINE, CINAHL, Web of Science and Cochrane Central Register of Controlled Trials databases. Results: Only three of 2084 studies detected and analyzed by performing the proposed searches in the detailed databases, were finally selected for this review, of which one was with and two were without intervention. These studies only weakly support a relationship between the gut microbiome and OA, specifically a correlation between certain taxa or microbial products and the inflammatory landscape and severity of OA symptoms, including knee pain. Conclusions: Despite encouraging results, this review highlights the paucity of high-quality studies addressing the potential role of the gut microbiome in OA-re-lated pain, along with the disparity of the techniques used so far, making it impossible to draw firm conclusions on the topic
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