1,729 research outputs found

    The logic and linguistic model for automatic extraction of collocation similarity

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    The article discusses the process of automatic identification of collocation similarity. The semantic analysis is one of the most advanced as well as the most difficult NLP task. The main problem of semantic processing is the determination of polysemy and synonymy of linguistic units. In addition, the task becomes complicated in case of word collocations. The paper suggests a logical and linguistic model for automatic determining semantic similarity between colocations in Ukraine and English languages. The proposed model formalizes semantic equivalence of collocations by means of semantic and grammatical characteristics of collocates. The basic idea of this approach is that morphological, syntactic and semantic characteristics of lexical units are to be taken into account for the identification of collocation similarity. Basic mathematical means of our model are logical-algebraic equations of the finite predicates algebra. Verb-noun and noun-adjective collocations in Ukrainian and English languages consist of words belonged to main parts of speech. These collocations are examined in the model. The model allows extracting semantically equivalent collocations from semi-structured and non-structured texts. Implementations of the model will allow to automatically recognize semantically equivalent collocations. Usage of the model allows increasing the effectiveness of natural language processing tasks such as information extraction, ontology generation, sentiment analysis and some others

    Efficient microwave synthesis of novel aromatic esters catalyzed by zirconia and its modified forms: a kinetic study

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    A series of solid acids such as ZrO2, 5% Mo(VI)/ZrO2, 10% Mo(VI)/ZrO2, 20% Mo(VI)/ZrO2 and SO42-/ZrO2 were prepared. These solid acids were characterized by BET, NH3-TPD/n-butylamine back titration, powder-XRD, FT-IR spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and ICP-OES techniques. The catalytic performance of these solid acids was evaluated in the synthesis of novel aromatic esters by the assistance of microwave irradiation and the catalytic activity of these solid acids was compared with pTsOH. The results clearly indicated that the zirconia based solid acids are efficient green catalysts for esterification reactions, which gave a maximum yield of the ester in a shorter reaction time and comparable catalytic activity of the pTsOH Bronsted acid. Kinetic studies were carried out to calculate the temperature coefficients (1.66 and 1.56) and energy of activation (66.82 kJ mol(-1) and 58.93 kJ mol(-1)) for SO42-/ZrO2 and pTsOH respectively. Pre-adsorption studies revealed that the reaction follows the Langmuir-Hinshelwood mechanism. The SO42-/ZrO2 solid acid catalyst was found to be reactivable and reusable

    Non-linear IVIV characteristics in two-dimensional superconductors: Berezinskii-Kosterlitz-Thouless physics vs inhomogeneity

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    One of the hallmarks of the Berezinskii-Kosterlitz-Thouless (BKT) transition in two-dimensional (2D) superconductors is the universal jump of the superfluid density, that can be indirectly probed via the non-linear exponent of the current-voltage IVIV characteristics. Here, we compare the experimental measurements of IVIV characteristics in two cases, namely NbN thin films and SrTiO3_3-based interfaces. While the former display a paradigmatic example of BKT-like non-linear effects, the latter do not seem to justify a BKT analysis. Rather, the observed IVIV characteristics can be well reproduced theoretically by modelling the effect of mesoscopic inhomogeneity of the superconducting state. Our results offer an alternative perspective on the spontaneous fragmentation of the superconducting background in confined 2D systems.Comment: Final version, as publishe

    Surgical Stabilization of Femur Fractures in Post-Traumatic Hypoxemic Patients: When and Why?

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    Background: Post-traumatic hypoxemia can deteriorate during operative manipulations. Objectives: In the present study, criteria-based approach was applied to determine optimum conditions for femur surgery. The aim of this study was to optimize perioperative management of post-traumatic hypoxemia. Patients and Methods: In this prospective observational study, post-traumatic adults with PaO2 200 mmHg (FiO2 < 0.5, PEEP < 8 cm H2O). Results: A total of 31 adults (26 males and 5 females) with LIS of 0.1 to 2.5 (26 patients) and > 2.5 (five patients) at admission were recruited. Sixteen patients were admitted within 24 hours and 15 between 24 and 90 hours after injury. Thirteen patients were operated within 24 hours. Post-operative LIS was improved. No adverse sequels or mortality were seen. Conclusions: Appropriate surgical stabilization can be safely performed during established post-traumatic hypoxemia using a multidisciplinary approach, continuous monitoring, and serial investigations to diagnose fulminant pathology and associated injuries

    Probability distribution of persistent spins in a Ising chain

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    We study the probability distribution Q(n,t)Q(n,t) of n(t)n(t), the fraction of spins unflipped till time tt, in a Ising chain with ferromagnetic interactions. The distribution shows a peak at n=nmaxn=n_{max} and in general is non-Gaussian and asymmetric in nature. However for n>nmaxn>n_{max} it shows a Gaussian decay. A data collapse can be obtained when Q(n,t)/LαQ(n,t)/L^{\alpha} versus (nnmax)Lβ(n-n_{max})L^{\beta} is plotted with α0.45\alpha \sim 0.45 and β0.6\beta \sim 0.6. Interestingly, nmax(t)n_{max}(t) shows a different behaviour compared to =P(t) = P(t), the persistence probability which follows the well-known behaviour P(t)tθP(t)\sim t^{-\theta}. A quantitative estimate of the asymmetry and non-Gaussian nature of Q(n,t)Q(n,t) is made by calculating its skewness and kurtosis.Comment: 4 pages, submitted to J. Phys

    Three Spin Spiky Strings in beta-deformed Background

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    We study rigidly rotating strings in β\beta-deformed AdS5×S5AdS_5\times S^5 background with one spin along AdS5_5 and two angular momenta along S5S^5. We find the spiky string solutions and present the dispersion relation among various charges in this background. We further generalize the result to the case of four angular momenta along AdS5×Sγ5AdS_5 \times S_{\gamma}^5.Comment: 12 pages, minor corrections, added references, to appear in JHE

    CH radio emission from heiles cloud 2 as a tracer of molecular cloud evolution

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    A mapping observation of the J=1/2J=1/2 Λ\Lambda-type doubling transition (3.3 GHz) of CH has been conducted toward Heiles Cloud 2 (HCL2) in the Taurus molecular cloud complex to reveal its molecular cloud-scale distribution. The observations were carried out with the Effelsberg 100 m telescope. The CH emission is found to be extended over the whole region of HCL2. It is brighter in the southeastern part, which encloses the TMC-1 cyanopolyyne peak than in the northwestern part. Its distribution extends continuously from the peak of the neutral carbon emission (CI peak) to the TMC-1 ridge, as if it were connecting the distributions of the [C I] and C18^{18}O emissions. Since CH is an intermediate in gas-phase chemical reactions from C to CO, its emission should trace the transition region. The above distribution of the CH emission is consistent with this chemical behavior. Since the CH abundance is subject to the chemical evolutionary effect, the CH column density in HCL2 no longer follows a linear correlation wit the H2_2 column density reported for diffuse and translucent clouds. More importantly, the CH line profile is found to be composed of the narrow and broad components. Although the broad component is dominant around the CI peak, the narrow component appears in the TMC-1 ridge and dense core regions such as L1527 and TMC-1A. This trend seems to reflect a narrowing of the line width during the formation of dense cores. These results suggest that the 3.3 GHz CH line is a useful tool for tracing the chemical and physical evolution of molecular clouds.Comment: 8 page

    A photoionization model of the compact HII region G29.96-0.02

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    We present a detailed photoionization model of G29.96-0.02 (hereafter G29.96), one of the brightest Galactic Ultra Compact HII (UCHII) regions in the Galaxy. This source has been observed extensively at radio and infrared wavelengths. The most recent data include a complete ISO (SWS and LWS) spectrum, which displays a remarkable richness in atomic fine-structure lines. The number of observables is twice as much as the number available in previous studies. In addition, most atomic species are now observed in two ionization stages. The radio and infrared data on G29.96 are best reproduced using a nebular model with two density components: a diffuse (n_e~680cm-3) extended (~1 pc) component surrounding a compact (~0.1 pc) dense (n_e~57000cm-3) core. The properties of the ionizing star were derived using state-of-the-art stellar atmosphere models. CoStar models yield an effective temperature of \~30^{+2}_{-1} kK whereas more recent non-LTE line blanketed atmospheres with stellar winds indicate somewhat higher values, Teff~32--38 kK. This range in Teff is compatible with all observational constraints, including near-infrared photometry and bolometric luminosity. The range 33-36 kK is also compatible with the spectral type O5-O8 determined by Watson and Hanson (97) when recent downward revisions of the effective temperature scale of O stars are taken into account. The age of the ionizing star of G29.96 is found to be a few 10^6 yr, much older than the expected lifetime of UCHII regions. Accurate gas phase abundances are derived with the most robust results being Ne/S=7.5 and N/O=0.43 (1.3 and 3.5 times the solar values, respectively).Comment: Accepted in Astronomy and Astrophysic

    Higher order antibunching is not a rare phenomenon

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    Since the introduction of higher order nonclassical effects, higher order squeezing has been reported in a number of different physical systems but higher order antibunching is predicted only in three particular cases. In the present work, we have shown that the higher order antibunching is not a rare phenomenon rather it can be seen in many simple optical processes. To establish our claim, we have shown it in six wave mixing process, four wave mixing process and in second harmonic generation process.Comment: 6 pages, no figure, Latex 2
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