161 research outputs found

    Forgetfulness of continuous Markovian quantum channels

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    The notion of forgetfulness, used in discrete quantum memory channels, is slightly weakened in order to be applied to the case of continuous channels. This is done in the context of quantum memory channels with Markovian noise. As a case study, we apply the notion of weak-forgetfulness to a bosonic memory channel with additive noise. A suitable encoding and decoding unitary transformation allows us to unravel the effects of the memory, hence the channel capacities can be computed using known results from the memoryless setting.Comment: 6 pages, 2 figures, comments are welcome. Minor corrections and acknoledgment adde

    Quantum Carousel: The Fate of a Bound State Attached to a Linear Rotor

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    We study the angulon problem -- a linear rotor in a bosonic bath -- in the regime where attractive impurity-boson interactions can support a shallow bound state. To study the fate of the angulon in the vicinity of bound-state formation, we formulate a beyond-linear-coupling model. First, we consider attractive, spherically symmetric impurity-boson interactions for which the linear rotor can be mapped onto a static impurity. The well-known polaron formalism provides an adequate description in this limit. For anisotropic potentials, the presence of a shallow bound state with pronounced anisotropic character leads to a many-body instability that washes out the angulon dynamics

    The GstLAL Search Analysis Methods for Compact Binary Mergers in Advanced LIGO's Second and Advanced Virgo's First Observing Runs

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    After their successful first observing run (September 12, 2015 - January 12, 2016), the Advanced LIGO detectors were upgraded to increase their sensitivity for the second observing run (November 30, 2016 - August 26, 2017). The Advanced Virgo detector joined the second observing run on August 1, 2017. We discuss the updates that happened during this period in the GstLAL-based inspiral pipeline, which is used to detect gravitational waves from the coalescence of compact binaries both in low latency and an offline configuration. These updates include deployment of a zero-latency whitening filter to reduce the over-all latency of the pipeline by up to 32 seconds, incorporation of the Virgo data stream in the analysis, introduction of a single-detector search to analyze data from the periods when only one of the detectors is running, addition of new parameters to the likelihood ratio ranking statistic, increase in the parameter space of the search, and introduction of a template mass-dependent glitch-excision thresholding method.Comment: 12 pages, 7 figures, to be submitted to Phys. Rev. D, comments welcom

    Silvicultural management and altitude prevail on soil properties and fungal community in shaping understorey plant communities in a Mediterranean pine forest

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    Understorey vegetation plays a key role in Mediterranean forest ecosystem functioning. However, we still lack a thorough understanding of the patterns and drivers of understorey composition and diversity. As a result, understoreys are often ignored during assessments of forest functioning under climate change. Here we studied the effect of silvicultural management, topography, soil fungal community composition and soil physical and chemical properties on understorey community composition and diversity. The plant cover and number of individuals of understorey perennial plants, shrubs and non-dominant trees was recorded on 24 plots (paired: control-thinned) in a Mediterranean pine-dominated mountainous area in Northeast Spain. The study area represented a broad thinning intensity gradient (from 0 to 70 % in removed stand basal area) along a 400-m altitudinal range (from 609 m to 1013 m). Our results showed that thinning intensity and topography explained the greatest proportion of the total variance in the understorey species composition, i.e., 18 % and 16 %, respectively. Interestingly, the effects of the silvicultural treatments were significant only when considering the altitudinal effect, so that, the main impacts of thinning on the understorey community composition occurred at low altitudes (between 609 m and 870 m). Moreover, we found a significant decrease in both richness and abundance of understorey species in both the control and thinned plots with increasing altitude, with thinned plots being significantly richer in species compared to the control plots. The difference in the understorey community sensitivity to forest thinning along the altitudinal gradient suggests changes in factors that limit plant growth. Low elevation plots were restrained by light availability while high altitudes plots limited by winter freezing temperatureThis work was supported by the Spanish Ministry of Science and Innovation and Universities (RTI2018-099315-A-I00). Josu G. Alday was supported by Ramon y Cajal fellowship (RYC-2016-20528). José Antonio Bonet and Sergio de Miguel benefitted from a Serra-Húnter Fellowship provided by the Generalitat of Catalonia

    Determination of set-membership identifiability sets

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    International audienceThis paper concerns the concept of set-membership identifiability introduced in \cite{jauberthie}. Given a model, a set-membership identifiable set is a connected set in the parameter domain of the model such that its corresponding trajectories are distinct to trajectories arising from its complementary. For obtaining the so-called set-membership identifiable sets, we propose an algorithm based on interval analysis tools. The proposed algorithm is decomposed into three parts namely {\it mincing}, {\it evaluating} and {\it regularization} (\cite{jaulin2}). The latter step has been modified in order to obtain guaranteed set-membership identifiable sets. Our algorithm will be tested on two examples

    Maximum-Likelihood Parameter Estimation in Terahertz Time-Domain Spectroscopy

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    We present a maximum-likelihood method for parameter estimation in terahertz time-domain spectroscopy. We derive the likelihood function for a parameterized frequency response function, given a pair of time-domain waveforms with known time-dependent noise amplitudes. The method provides parameter estimates that are superior to other commonly used methods and provides a reliable measure of the goodness of fit. We also develop a simple noise model that is parameterized by three dominant sources and derive the likelihood function for their amplitudes in terms of a set of repeated waveform measurements. We demonstrate the method with applications to material characterization

    Izolacija i sposobnost hvatanja slobodnih radikala cijanidin 3-O-glikozida iz plodova Ribes biebersteinii Berl.

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    The reversed-phase preparative high performance liquid chromatographic purification of the methanol extract of the fruits of Ribes biebersteinii Berl. (Grossulariaceae) afforded five cyanidin glycosides, 3-O-sambubiosyl-5-O-glucosyl cyanidin (1), cyanidin 3-O-sambubioside (2), cyanidin 3-O-glucoside (3), cyanidin 3-O-(2G-xylosyl)-rutinoside (4) and cyanidin 3-O-rutinoside (5). They showed considerable free-radical-scavenging properties in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay with the RC50 values of 9.29 × 106, 9.33 × 106, 8.31 × 106, 8.96 × 106 and 9.55 × 106 mol L1, respectively. The structures of these compounds were elucidated by various chemical hydrolyses and spectroscopic means. The total anthocyanin content was 1.9 g per 100 g dried fruits on cyanidin 3-glucoside basis.Pet cijanidin glikozida, 3-O-sambubiozil-5-O-glukozil cijanidin (1), cijanidin 3-O-sambubiozid (2), cijanidin 3-O-glukozid (3), cijanidin 3-O-(2G-ksilozil)-rutinozid (4) i cijanidin 3-O-rutinosid (5) izolirani su iz metanolnog ekstrakta plodova Ribes biebersteinii Berl. (Grossulariaceae) koristeći reverzno-faznu preparativnu tekućinsku kromatografiju visoke učinkovitosti. Cijanidin glikozidi pokazali su sposobnost hvatanja slobodnih radikala u pokusu s 2,2-difenil-1-pikrilhidrazilom (DPPH). Dobivene su sljedeće RC50 vrijednosti: 9,29 × 106, 9,33 × 106, 8,31 × 106, 8,96 × 106, odnosno 9,55 × 106 mol L1. Strukture glikozida određene su kemijskom hidrolizom i spektroskopijom masa. Ukupni sadržaj antocijanina bio je 1,9 g na 100 g suhih plodova preračunato na cijanidin 3-glukozid
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