Search results for "DF"
showing 10 items of 1699 documents
Experimental Observations of Flow and Bed Processes in Large-Amplitude Meandering Flume
2009
Meanders of large amplitude often exhibit asymmetric planform shape or subsidiary bends. The present work is aimed at improving on understanding of the morphodynamic phenomena affecting the bed evolution of large amplitude meandering channels. Attention is focused on the development of the steady point bar-pool configuration and of the superimposed large-scale migrating bed forms; of particular interest is the role of the changing channel curvature and bed topography variation on flow pattern. A series of experiments was carried out in a sine-generated large-amplitude meandering flume, for two values of width-to-depth ratio. Maps documenting the bed topography and the flow pattern along the…
Experimental observations of upstream overdeepening
2005
The issue of morphodynamic influence in meandering streams is investigated through a series of laboratory experiments on curved and straight flumes. Both qualitative and quantitative observations confirm the suitability of the recent theoretical developments (Zolezzi & Seminara 2001) that indicate the occurrence of two distinct regimes of morphodynamic influence, depending on the value of the width ratio of the channel β. The threshold value βR separating the upstream from the downstream influence regimes coincides with the resonant value discovered by Blondeaux & Seminara (1985). Indeed it is observed that upstream influence may occur only in relatively wide channels, while narrower stream…
Color constancy in goldfish: the limits
2000
Color constancy was investigated in behavioral training experiments on colors ranging from blue to yellow, located in the color space close to Planck's locus representing the main changes in natural skylight. Two individual goldfish were trained to peck at a test field of medium hue out of a series of 13-15 yellowish and bluish test fields presented simultaneously on a black background. During training the tank in which the fish were swimming freely was illuminated with white light. Correct choices were rewarded with food. During the tests differently saturated yellow or blue illumination was used. The degree of color constancy was inferred from the choice behavior under these illuminations…
Protective role of mindfulness, self-compassion and psychological flexibility on the burnout subtypes among psychology and nursing undergraduate stud…
2021
Abstract To explore the relationship between mindfulness, self-compassion and psychological flexibility, and the burnout subtypes in university students of the Psychology and Nursing degrees, and to analyse possible risk factors for developing burnout among socio-demographic and studies-related characteristics. Design Cross-sectional study conducted on a sample of 644 undergraduate students of Nursing and Psychology from two Spanish universities. Methods The study was conducted between December 2015 and May 2016. Bivariate Pearson's correlations were computed to analyse the association between mindfulness facets, self-compassion and psychological flexibility, and levels of burnout. Multivar…
Oracle risinājumu pielietojums Big Data kontekstā
2016
Maģistra darbā tika apskatīti un analizēti Oracle un citu ražotāju piedāvātie risinājumi Big Data apstrādei un analīzei. Darbs satur teorētisku dažādu ražotāju rīku apskati un salīdzinājumu, kā arī praktisko daļu, kurā tiek analizētas datu savienošanas iespējas hibrīdā datu noliktavā. Par hibrīdo datu noliktavu tiek uzskatīta tāda datu noliktava, kurā daļa datu atrodas RDBMS sistēmā un daļa datu HDFS sistēmā. Darba galvenie mērķi ir analizēt šāda veida sistēmas veiktspēju, izmantojot dažādus datu apvienošanas veidus. Testu laikā tika apskatīti apskatīti gadījumi, kad datu apvienošana notiek RDBMS sistēmas pusē un gadījumi, kad datu apvienošana notiek HDFS sistēmas pusē, kā arī tika izpētīta…
A comparison of HDFS compact data formats: Avro versus Parquet
2017
In this paper, file formats like Avro and Parquet are compared with text formats to evaluate the performance of the data queries. Different data query patterns have been evaluated. Cloudera’s open-source Apache Hadoop distribution CDH 5.4 has been chosen for the experiments presented in this article. The results show that compact data formats (Avro and Parquet) take up less storage space when compared with plain text data formats because of binary data format and compression advantage. Furthermore, data queries from the column based data format Parquet are faster when compared with text data formats and Avro. Article in English. HDFS glaustųjų duomenų formatų palyginimas: Avro prieš Parquet…
A systematic review of SQL-on-Hadoop by using compact data formats
2016
Article also submitted for publication in Baltic J. Modern Computing (BJMC) on October 5, 2016.
Diorganotin(IV) N-acetyl-L-cysteinate complexes: synthesis, solid state, solution phase, DFT and biological investigations.
2009
Diorganotin(IV) complexes of N-acetyl-L-cysteine (H(2)NAC; (R)-2-acetamido-3-sulfanylpropanoic acid) have been synthesized and their solid and solution-phase structural configurations investigated by FTIR, Mössbauer, (1)H, (13)C and (119)Sn NMR spectroscopy. FTIR results suggested that in R(2)Sn(IV)NAC (R = Me, Bu, Ph) complexes NAC(2-) behaves as dianionic tridentate ligand coordinating the tin(IV) atom, through ester-type carboxylate, acetate carbonyl oxygen atom and the deprotonated thiolate group. From (119)Sn Mössbauer spectroscopy it could be inferred that the tin atom is pentacoordinated, with equatorial R(2)Sn(IV) trigonal bipyramidal configuration. In DMSO-d(6) solution, NMR spectr…
Biogenic Selenium Nanoparticles: A Fine Characterization to Unveil Their Thermodynamic Stability
2021
Among the plethora of available metal(loid) nanomaterials (NMs), those containing selenium are interesting from an applicative perspective, due to their high biocompatibility. Microorganisms capable of coping with toxic Se-oxyanions generate mostly Se nanoparticles (SeNPs), representing an ideal and green alternative over the chemogenic synthesis to obtain thermodynamically stable NMs. However, their structural characterization, in terms of biomolecules and interactions stabilizing the biogenic colloidal solution, is still a black hole that impairs the exploitation of biogenic SeNP full potential. Here, spherical and thermodynamically stable SeNPs were produced by a metal(loid) tolerant Mic…
Seasonal benthic nepheloid layer in the Gulf of Riga, Baltic Sea: Sources, structure and geochemical interactions
2005
Abstract The sources of particles, as well as the geochemical structure and interfacial exchange were studied for the summer benthic nepheloid layer of the shallow (50 m) Gulf of Riga. The material was sampled at nine stations during three cruises of August 2001–2003 with a main focus on the deep waters. Suspended particulate matter (SPM) and its major (N, Si, P, Al, Fe, Mn, Ca) elements were determined as the principal parameters. The results indicate the summer benthic nepheloid layer as an important component of the environmental regime of the Gulf of Riga. The nepheloid layer develops as a result of the near-bottom hydrodynamics and a corresponding saline structure below the thermocline…