Search results for "LDA"

Determination of ammonia and primary amine compounds and Kjeldahl nitrogen in water samples with a modified Roth's fluorimetric method.

2005

Abstract A method for the simultaneous determination of primary amino groups and ammonium ion has been proposed. The method is based in solution derivatization with o-Phthaldialdehyde/N-acetyl-cisteine (OPA/NAC) and fluorescence measurement of the formed isoindols. Analytical characteristics and description of the developed procedure have been provided. The calibration graphs for ammonium (up to 1.44 mg L−1 of N) and methylamine as primary amino model compound (up to 0.282 mg L−1 of N), were obtained. Bivariate and multivariate calibration models have been tested. The limits of detection were 0.07 mg L−1 of N and 0.004 mg L−1 of N for ammonium and amine, respectively. The procedure was firs…

Zvaigžņotā Debess: 2017/18, Ziema (238)

2017

Contents: “ZVAIGŽŅOTĀ DEBESS” FORTY YEARS AGO: I.Vilka. Starry Sky and Birds’ Journeys (abridged) ; N.Cimahoviča. Spirals of Saturn’s Rings (abridged) ; I.Šmelds. V Readings of Friedrich Zander ; DEVELOPMENTS in SCIENCE: K.Schwartz. Most Distant Galaxy Clusters and 3D Structure of the Universe ; DISCOVERIES: M.Gills. The Day when Multi-Messenger Astronomy Was Announced ; I.Pundure. ESO Telescopes and Hubble Observe the Source of Gravitational Waves for the First Time ; I.Eglītis. Asteroid “Balklavs” ; SPACE RESEARCH and EXPLORATION: R.Misa. Mission of Cassini – Discoveries to the Very End ; J.Jaunbergs. The Icy World Tethys ; OBSERVATORIES and INSTRUMENTS: M.Gills. The Giant Radio Telescope…

Exploring topics in LDA models through Statistically Validated Networks: directed and undirected approaches

2022

Probabilistic topic models are machine learning tools for processing and understanding large text document collections. Among the different models in the literature, Latent Dirichlet Allocation (LDA) has turned out to be the benchmark of the topic modelling community. The key idea is to represent text documents as random mixtures over latent semantic structures called topics. Each topic follows a multinomial distribution over the vocabulary words. In order to understand the result of a topic model, researchers usually select the top-n (essential words) words with the highest probability given a topic and look for meaningful and interpretable semantic themes. This work proposes a new method …

Folding Patterns in a Family of Oligoamide Foldamers

2015

A series of small, unsymmetrical pyridine-2,6-dicarboxylamide oligoamide foldamers with varying lengths and substituents at the end groups were synthetized to study their conformational properties and folding patterns. The @-type folding pattern resembled the oxyanion-hole motifs of enzymes, but several alternative folding patterns could also be characterized. Computational studies revealed several alternative conformers of nearly equal stability. These folding patterns differed from each other in their intramolecular hydrogen-bonding patterns and aryl-aryl interactions. In the solid state, the foldamers adopted either the globular @-type fold or the more extended S-type conformers, which w…

Conformational properties and folding analysis of a series of seven oligoamide foldamers

2016

33 crystal structures (11 unsolvated and 22 solvates) of a series of seven oligoamide foldamers were analysed. The crystal structures revealed that despite the structural and environmental differences the series of foldamers prefer only two general conformations, a protohelical @-conformation and a sigmoidal S-conformation. Both conformations also have preferred crystal packing motifs and solvate forming tendencies. Hydrogen bonding was found to be the most decisive factor in conformational preference, but steric properties, the type of the peripheral substituents, as well as solvent and aromatic interactions were also found to have an effect on the conformational details and crystal form. …

Prøver, måling og og evaluering – pedagogiske utviklingsverktøy eller måleredskaper? Et kritisk perspektiv på vurderende og dokumenterende sakprosa i…

2018

Lederartikkelen gir en presentasjon av temanummeret  Evalueringens sakprosa. Seks studier av evaluerende tekster i barnehage og skole  og setter temaet i et kritisk perspektiv. Det slas fast at temanummerets artikler spenner fra det deskriptive til det kritisk-normative, fra det elevorienterte til det byrakratiorientere, og fra fokus pa tekst til fokus pa sosial praksis. The editorial article is a presentation of the theme issue  Evaluation saksprosa. Six studies of evaluative texts in kindergarten and school  and situates the topic in a critical perspective. The editors state that the theme number's articles range from the descriptive to the critical-normative, from the student-oriented to…

Liturgical literacy as hidden capital : Experiences from Qur’an education in Sweden

2019

This article focuses on a form of supplementary Islamic education that centres on Qur’an studies and examines the reported experiences of Muslim students that regularly shift between this and their mainstream secular school. Its aim is to better comprehend the dialectical interplay between this type of supplementary education and mainstream secular schooling. Within this framework, the article explores how the traditional way of reading, reciting, and memorizing the Qur’an might relate to the type of teaching and learning that occurs within mainstream public schools. It also explores the possibility of a secular bias within the Swedish school system, the contribution of Qur’an studies to ma…

Kollokationen in Leserbriefen der Wochenzeitschrift Die Zeit

2020

Im Rahmen der Phraseologieforschung haben Kollokationen traditionell nur wenig Beachtung gefunden. Im Gegensatz zu Idiomen sind sie in der Regel semantisch transparent und bereiten daher Fremdsprachenlernern selten rezeptive Schwierigkeiten. Bei der Textproduktion muss jedoch die Problematik der Kollokationen beachtet werden. Aus diesem Grund halten wir Kollokationen für einen wichtigen Bereich der Phraseologie. Im vorliegenden Beitrag wird die Aufmerksamkeit auf die syntaktische Struktur, den Gebrauch und die Funktion von Kollokationen in 243 Leserbriefen der Zeitschrift Die Zeit gerichtet. Nach Heranziehung zweier Kollokationswörterbücher sowie einiger anderer Quellen konnten 278 Kollokat…

MINERALIZZAZIONE DEL CARBONIO IN SUOLI BOSCHIVI DOPO RISCALDAMENTO ED INUMIDIMENTO CONTROLLATI

2011

Supramolecular chirality and symmetry breaking of fluoride complexes of achiral foldamers

2017

Aromatic oligoamide foldamers containing a central pyridine-2,6-dicarbonyl motif are partially preorganized to favor the binding of fluoride anions. In the solid state, the foldamer-fluoride complexes form achiral, polar and chiral crystal structures depending on the chemical structure of the foldamer. One of the six foldamers studied here, a C2v symmetrical foldamer (1), formed repeatedly chiral crystal structures when crystallized with tetra-butylammonium fluoride, showing supramolecular bulk chirality and symmetry breaking in crystallization.