567 research outputs found
Use of an experimental design model to determine the impact of different fermentation parameters on the development of flavour compounds in wine
An experimental design developed by YOUDEN and STEINER (1975) was successfully applied to micro-fermentation experiments with two different grape musts. This tool allowed the verification of the impact of several fermentation parameters on the fermentation course and on flavour development with a restricted number of experiments. The positive effects of a higher fermentation temperature on the development of 3-mercaptohexanol, an important contributor to the characteristic aroma of the Petite Arvine wine, could be demonstrated.
Investigation of ripple-limited low-field mobility in large-scale graphene nanoribbons
Combining molecular dynamics and quantum transport simulations, we study the degradation of mobility in graphene nanoribbons caused by substrate-induced ripples. First, the atom coordinates of large-scale structures are relaxed such that surface properties are consistent with those of graphene on a substrate. Then, the electron current and low-field mobility of the resulting non-flat nanoribbons are calculated within the Non-equilibrium Green\u27s Function formalism in the coherent transport limit. An accurate tight-binding basis coupling the sigma- and pi-bands of graphene is used for this purpose. It is found that the presence of ripples decreases the mobility of graphene nanoribbons on SiO2 below 3000 cm(2)/Vs, which is comparable to experimentally reported values. (C) 2013 AIP Publishing LLC
Improving Blind Spot Denoising for Microscopy
Many microscopy applications are limited by the total amount of usable light
and are consequently challenged by the resulting levels of noise in the
acquired images. This problem is often addressed via (supervised) deep learning
based denoising. Recently, by making assumptions about the noise statistics,
self-supervised methods have emerged. Such methods are trained directly on the
images that are to be denoised and do not require additional paired training
data. While achieving remarkable results, self-supervised methods can produce
high-frequency artifacts and achieve inferior results compared to supervised
approaches. Here we present a novel way to improve the quality of
self-supervised denoising. Considering that light microscopy images are usually
diffraction-limited, we propose to include this knowledge in the denoising
process. We assume the clean image to be the result of a convolution with a
point spread function (PSF) and explicitly include this operation at the end of
our neural network. As a consequence, we are able to eliminate high-frequency
artifacts and achieve self-supervised results that are very close to the ones
achieved with traditional supervised methods.Comment: 15 pages, 4 figure
On Landauer vs. Boltzmann and Full Band vs. Effective Mass Evaluation of Thermoelectric Transport Coefficients
The Landauer approach to diffusive transport is mathematically related to the
solution of the Boltzmann transport equation, and expressions for the
thermoelectric parameters in both formalisms are presented. Quantum mechanical
and semiclassical techniques to obtain from a full description of the
bandstructure, E(k), the number of conducting channels in the Landauer approach
or the transport distribution in the Boltzmann solution are developed and
compared. Thermoelectric transport coefficients are evaluated from an atomistic
level, full band description of a crystal. Several example calculations for
representative bulk materials are presented, and the full band results are
related to the more common effective mass formalism. Finally, given a full E(k)
for a crystal, a procedure to extract an accurate, effective mass level
description is presented.Comment: 33 pages, 8 figure
Cytoplasmic cleavage of IMPA1 3' UTR is necessary for maintaining axon integrity
The 3′ untranslated regions (3′ UTRs) of messenger RNAs (mRNAs) are non-coding sequences involved in many aspects of mRNA metabolism, including intracellular localization and translation. Incorrect processing and delivery of mRNA cause severe developmental defects and have been implicated in many neurological disorders. Here, we use deep sequencing to show that in sympathetic neuron axons, the 3′ UTRs of many transcripts undergo cleavage, generating isoforms that express the coding sequence with a short 3′ UTR and stable 3′ UTR-derived fragments of unknown function. Cleavage of the long 3′ UTR of Inositol Monophosphatase 1 (IMPA1) mediated by a protein complex containing the endonuclease argonaute 2 (Ago2) generates a translatable isoform that is necessary for maintaining the integrity of sympathetic neuron axons. Thus, our study provides a mechanism of mRNA metabolism that simultaneously regulates local protein synthesis and generates an additional class of 3′ UTR-derived RNAs
Theory and simulation of quantum photovoltaic devices based on the non-equilibrium Green's function formalism
This article reviews the application of the non-equilibrium Green's function
formalism to the simulation of novel photovoltaic devices utilizing quantum
confinement effects in low dimensional absorber structures. It covers
well-known aspects of the fundamental NEGF theory for a system of interacting
electrons, photons and phonons with relevance for the simulation of
optoelectronic devices and introduces at the same time new approaches to the
theoretical description of the elementary processes of photovoltaic device
operation, such as photogeneration via coherent excitonic absorption,
phonon-mediated indirect optical transitions or non-radiative recombination via
defect states. While the description of the theoretical framework is kept as
general as possible, two specific prototypical quantum photovoltaic devices, a
single quantum well photodiode and a silicon-oxide based superlattice absorber,
are used to illustrated the kind of unique insight that numerical simulations
based on the theory are able to provide.Comment: 20 pages, 10 figures; invited review pape
Widespread FUS mislocalization is a molecular hallmark of amyotrophic lateral sclerosis
Mutations causing amyotrophic lateral sclerosis (ALS) clearly implicate ubiquitously expressed and predominantly nuclear RNA binding proteins, which form pathological cytoplasmic inclusions in this context. However, the possibility that wild-type RNA binding proteins mislocalize without necessarily becoming constituents of cytoplasmic inclusions themselves remains relatively unexplored. We hypothesized that nuclear-to-cytoplasmic mislocalization of the RNA binding protein fused in sarcoma (FUS), in an unaggregated state, may occur more widely in ALS than previously recognized. To address this hypothesis, we analysed motor neurons from a human ALS induced-pluripotent stem cell model caused by the VCP mutation. Additionally, we examined mouse transgenic models and post-mortem tissue from human sporadic ALS cases. We report nuclear-to-cytoplasmic mislocalization of FUS in both VCP-mutation related ALS and, crucially, in sporadic ALS spinal cord tissue from multiple cases. Furthermore, we provide evidence that FUS protein binds to an aberrantly retained intron within the SFPQ transcript, which is exported from the nucleus into the cytoplasm. Collectively, these data support a model for ALS pathogenesis whereby aberrant intron retention in SFPQ transcripts contributes to FUS mislocalization through their direct interaction and nuclear export. In summary, we report widespread mislocalization of the FUS protein in ALS and propose a putative underlying mechanism for this process
A CANDLE for a deeper in-vivo insight
A new Collaborative Approach for eNhanced Denoising under Low-light Excitation (CANDLE) is introduced for the processing of 3D laser scanning multiphoton microscopy images. CANDLE is designed to be robust for low signal-to-noise ratio (SNR) conditions typically encountered when imaging deep in scattering biological specimens. Based on an optimized non-local means filter involving the comparison of filtered patches, CANDLE locally adapts the amount of smoothing in order to deal with the noise inhomogeneity inherent to laser scanning fluorescence microscopy images. An extensive validation on synthetic data, images acquired on microspheres and in vivo images is presented. These experiments show that the CANDLE filter obtained competitive results compared to a state-of-the-art method and a locally adaptive optimized non-local means filter, especially under low SNR conditions (PSNR < 8 dB). Finally, the deeper imaging capabilities enabled by the proposed filter are demonstrated on deep tissue in vivo images of neurons and fine axonal processes in the Xenopus tadpole brain.We want to thank Florian Luisier for providing free plugin of his PureDenoise filter. We also want to thank Markku Makitalo for providing the code of their OVST. This study was supported by the Canadian Institutes of Health Research (CIHR, MOP-84360 to DLC and MOP-77567 to ESR) and Cda (CECR)-Gevas-OE016. MM holds a fellowship from the Deutscher Akademischer Austasch Dienst (DAAD) and a McGill Principal's Award. ESR is a tier 2 Canada Research Chair. This work has been partially supported by the Spanish Health Institute Carlos III through the RETICS Combiomed, RD07/0067/2001. This work benefited from the use of ImageJ.Coupé, P.; Munz, M.; Manjón Herrera, JV.; Ruthazer, ES.; Collins, DL. (2012). A CANDLE for a deeper in-vivo insight. Medical Image Analysis. 16(4):849-864. https://doi.org/10.1016/j.media.2012.01.002S84986416
Search for CP violation in D+→ϕπ+ and D+s→K0Sπ+ decays
A search for CP violation in D + → ϕπ + decays is performed using data collected in 2011 by the LHCb experiment corresponding to an integrated luminosity of 1.0 fb−1 at a centre of mass energy of 7 TeV. The CP -violating asymmetry is measured to be (−0.04 ± 0.14 ± 0.14)% for candidates with K − K + mass within 20 MeV/c 2 of the ϕ meson mass. A search for a CP -violating asymmetry that varies across the ϕ mass region of the D + → K − K + π + Dalitz plot is also performed, and no evidence for CP violation is found. In addition, the CP asymmetry in the D+s→K0Sπ+ decay is measured to be (0.61 ± 0.83 ± 0.14)%
Differential branching fraction and angular analysis of the decay B0→K∗0μ+μ−
The angular distribution and differential branching fraction of the decay B 0→ K ∗0 μ + μ − are studied using a data sample, collected by the LHCb experiment in pp collisions at s√=7 TeV, corresponding to an integrated luminosity of 1.0 fb−1. Several angular observables are measured in bins of the dimuon invariant mass squared, q 2. A first measurement of the zero-crossing point of the forward-backward asymmetry of the dimuon system is also presented. The zero-crossing point is measured to be q20=4.9±0.9GeV2/c4 , where the uncertainty is the sum of statistical and systematic uncertainties. The results are consistent with the Standard Model predictions
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