Search results for "NKT"
showing 10 items of 986 documents
A note on topological dimension, Hausdorff measure, and rectifiability
2020
The purpose of this note is to record a consequence, for general metric spaces, of a recent result of David Bate. We prove the following fact: Let $X$ be a compact metric space of topological dimension $n$. Suppose that the $n$-dimensional Hausdorff measure of $X$, $\mathcal H^n(X)$, is finite. Suppose further that the lower n-density of the measure $\mathcal H^n$ is positive, $\mathcal H^n$-almost everywhere in $X$. Then $X$ contains an $n$-rectifiable subset of positive $\mathcal H^n$-measure. Moreover, the assumption on the lower density is unnecessary if one uses recently announced results of Cs\"ornyei-Jones.
Assessing the influence of confounding biological factors when estimating bioaccumulation of PCBs with passive samplers in aquatic ecosystems
2017
Passive samplers are promising surrogates for organisms, mimicking bioaccumulation. However, several biological characteristics disturb the passive partitioning process in organisms by accelerating or restraining bioaccumulation, resulting in species-specific body residues of hydrophobic organic contaminants (HOCs). In addition to site-specific characteristics and HOC concentrations, age, sex, diet, biotransformation capability and habitat-specific characteristics may affect body residues. Two passive sampler types, polyethylene (PE) and polydimethylsiloxane (PDMS) were deployed in a PCB-contaminated freshwater lake water and sediment, respectively, to assess their bioaccumulation predictio…
Nyctiphanes couchii as intermediate host for Rhadinorhynchus sp. (Acanthocephala, Echinorhynchidae) from NW Iberian Peninsula waters
2013
12 páginas, 3 figuras, 3 tablas
Green sulphur bacteria as a component of the photosynthetic plankton community in small dimictic humic lakes with an anoxic hypolimnion
2013
High bacteriochlorophyll (BChl) concentrations in the anoxic water layers of some humic lakes have indicated that green sulphur bacteria (GSB) may be ecologically significant. The abundance and spatial distribution of GSB were therefore addressed in 13 small humic lakes using fragment analysis and sequencing of PCR-amplified 16S rRNA genes. GSB were detected from lakes where the photosynthetically active radiation was at least 1.1 µE m �2 s �1 at the oxic� anoxic boundary layer. In these lakes, 13 to 42% of the 16S rRNA gene sequences of the anoxic water column were assigned to GSB. The spatial distribution of GSB was tightly correlated with the spectrophotometrically measured BChl concentr…
Analysis of the vertical distribution in a model of phytoplankton dynamics
2010
Phytoplankton often faces the dilemma of living in contrasting gradients of two essential resources: the light that comes from above and nutrients that are often supplied from below. In poorly mixed water columns, algae can be heterogeneously distributed, with thin layers of biomass found on the surface, in depth, or on the sediment surface. Here, we show that these patterns can result from intraspecific competition between light and nutrients. First, we present numerical solutions of a reaction-diffusion-taxis model for phytoplankton, nutrients and light. We argue that motile phytoplankton can form a thin layer under poorly mixed conditions. The numerical solution of this model indicates t…
Zooplankton, lipids and stable isotopes: importance of seasonal, latitudinal, and taxonomic differences
2010
We found considerable seasonal, latitudinal, and taxonomic differences in zooplankton lipid content and concur- rent d 13 C values of zooplankton. We collected cladoceran as well as cyclopoid and calanoid copepod zooplankton from boreal and subarctic lakes throughout a year, allowing us to study zooplankton likely subjected to different isotopic fractionation processes and with highly variable lipid contents. Considerable seasonal variation was observed in the differ- ence between bulk and lipid-extracted zooplankton d 13 C values, indicating that seasonally changing lipid content intro- duced notable variation in zooplankton d 13 C values. The difference between bulk and lipid-extracted ma…
Emission of iodine-containing volatiles by selected microalgae species
2014
In this study we present the results of an emission study of different phytoplankton samples in aqueous media treated with elevated ozone levels. Halocarbon measurements show that the samples tested released bromoform and different iodocarbons, including iodomethane, iodochloromethane and diiodomethane. Iodide and iodate levels in the liquid phase were representative of concentrations of surface water in a natural environment. Measurement of volatile iodine (I2) emissions from two diatom samples (Mediopyxis helysia and Porosira glacialis) and the background sample (F/2 medium from filtered natural seawater) showed that the quantity of evolved I2 depends on the ozone concentration in the air…
Autovadītāju psiholoģiskā skatpunkta skalas veidošana un sākotnējā validitātes pārbaude
2022
Pētījuma mērķis bija izveidot Autovadītāju psiholoģiskā skatpunkta skalu un veikt tās pirmreizējās validitātes pārbaudes. Pētījuma rezultātā izveidota Autovadītāju psiholoģiskā skatpunkta skala ar četrām apakšskalām, kas raksturo autovadītāju psiholoģiskā skatpunkta dimensijas – piesardzību, sadarbību, telpu un spriešanu. Pētījumā identificēti turpmākie skalas pilnveidošanas un izstrādes virzieni. Pētījumā piedalījās 648 autovadītāji. Autovadītāju psiholoģiskā skatpunkta skalas validitātes pārbaudēs izmantota Autovadītāju uzvedības aptauja (Reason et al., 1990), Starppersonu reakciju aptaujas (Davis, 1980) Psiholoģiskā skatpunkta skala un Empātisko rūpju skala, kā arī Pozitīvas autovadītāju…
Latvijas ūdeņu vides pētījumi un aizsardzība: LU Bioloģijas fakultātes Hidrobioloģijas katedras sekcijas referātu tēžu krājums (Rīga, 2012. gada 24. …
2012
Krājumā ievietotās LU 70.konferences LU Bioloģijas fakultātes Hidrobioloģijas katedras sekcijas referātu tēzes nav recenzētas.
The Calabrian Stage redefined
2008
The name Calabrian was introduced in the geological literature by the French stratigrapher Maurice Gignoux in 1910, and later described in his important monograph (633 pages) "Les formations marines pliocènes et quaternaires de l'Italie du sud et de la Sicile" published in 1913. Detailed data were provided on several sections (Santa Maria di Catanzaro, Caraffa, Monasterace, Palermo) and on their fossil content. The Calabrian Stage has commonly been used for over fifty years as the oldest subdivision of the Quaternary, notably in the time scales of Berggren & van Couvering (1974) and Haq & Eysinga (1987). However, after the GSSP for the Pliocene/Pleistocene boundary (P/P) was approved by INQ…