Search results for "3C"
showing 10 items of 396 documents
Volume preserving mean curvature flows near strictly stable sets in flat torus
2021
In this paper we establish a new stability result for the smooth volume preserving mean curvature flow in flat torus $\mathbb T^n$ in low dimensions $n=3,4$. The result says roughly that if the initial set is near to a strictly stable set in $\mathbb T^n$ in $H^3$-sense, then the corresponding flow has infinite lifetime and converges exponentially fast to a translate of the strictly stable (critical) set in $W^{2,5}$-sense.
Topological canal foliations
2019
Regular canal surfaces of $\mathbb{R}^3$ or $\mathbb{S}^3$ admit foliations by circles: the characteristic circles of the envelope. In order to build a foliation of $\mathbb{S}^3$ with leaves being canal surfaces, one has to relax the condition “canal” a little (“weak canal condition”) in order to accept isolated umbilics. Here, we define a topological condition which generalizes this “weak canal” condition imposed on leaves, and classify the foliations of compact orientable 3-manifolds we can obtain this way.
Acoustic wave guides as infinite-dimensional dynamical systems
2015
We prove the unique solvability, passivity/conservativity and some regularity results of two mathematical models for acoustic wave propagation in curved, variable diameter tubular structures of finite length. The first of the models is the generalised Webster's model that includes dissipation and curvature of the 1D waveguide. The second model is the scattering passive, boundary controlled wave equation on 3D waveguides. The two models are treated in an unified fashion so that the results on the wave equation reduce to the corresponding results of approximating Webster's model at the limit of vanishing waveguide intersection.
Dynamics of soil organic matter pools after agricultural abandonment
2014
Changes of land use from croplands to natural vegetation usually increase Carbon (C) stocks in soil. However, the contribution of old and new C to various pools still is not clearly analyzed.We measured the 13C signature of soil organic carbon (SOC) pools after vegetation change from vineyard (C3) to grassland (C4) under Mediterranean climate to assess the changes of old and new C in total SOC, microbial biomass (MB), dissolved organic C (DOC), and CO2 efflux from soil. Development of the perennial grass Hyparrhenia hirta (C4) on vineyard abandoned for 15 or 35 years ago increased C stocks for 13% and 16%, respectively (in the upper 15 cm). This increase was linked to the incorporation of n…
The variable food webs in cold-water lakes
2022
Titanocene Selenide Sulfides Revisited: Formation, Stabilities, and NMR Spectroscopic Properties
2019
[TiCp2S5] (phase A), [TiCp2Se5] (phase F), and five solid solutions of mixed titanocene selenide sulfides [TiCp2SexS5−x] (Cp = C5H5−) with the initial Se:S ranging from 1:4 to 4:1 (phases B–E) were prepared by reduction of elemental sulfur or selenium or their mixtures by lithium triethylhydridoborate in thf followed by the treatment with titanocene dichloride [TiCp2Cl2]. Their 77Se and 13C NMR spectra were recorded from the CS2 solution. The definite assignment of the 77Se NMR spectra was based on the PBE0/def2-TZVPP calculations of the 77Se chemical shifts and is supported by 13C NMR spectra of the samples. The following complexes in varying ratios were identified in the CS2 solutions of …
Functional inequalities for generalized inverse trigonometric and hyperbolic functions
2014
Various miscellaneous functional inequalities are deduced for the so-called generalized inverse trigonometric and hyperbolic functions. For instance, functional inequalities for sums, difference and quotient of generalized inverse trigonometric and hyperbolic functions are given, as well as some Gr\"unbaum inequalities with the aid of the classical Bernoulli inequality. Moreover, by means of certain already derived bounds, bilateral bounding inequalities are obtained for the generalized hypergeometric ${}_3F_2$ Clausen function.
Benthic foodweb structure in a large shallow lake studied by stable isotope analysis
2014
The benthic foodweb structure of Lake Võrtsjärv, a large (270 km2), shallow, and turbid Estonian lake, was evaluated based on C and N stable-isotope signatures (δ13C, δ15N). Variation in δ13C between sampling sites was not related to site proximity to the littoral zone or the more vegetated southern part of the lake, but rather appeared to be influenced by in-situ site peculiarities. δ13C was stable temporally and between functional feeding groups, a result implying that the whole benthic food web of the lake relies largely on the same C source admixture, essentially particulate organic matter (POM). Thus, the foodweb composition of Lake Võrtsjärv is remarkably homogeneous given the lake’s …
Inferring Phytoplankton, Terrestrial Plant and Bacteria Bulk δ¹³C Values from Compound Specific Analyses of Lipids and Fatty Acids.
2015
Stable isotope mixing models in aquatic ecology require δ13C values for food web end members such as phytoplankton and bacteria, however it is rarely possible to measure these directly. Hence there is a critical need for improved methods for estimating the δ13C ratios of phytoplankton, bacteria and terrestrial detritus from within mixed seston. We determined the δ13C values of lipids, phospholipids and biomarker fatty acids and used these to calculate isotopic differences compared to the whole-cell δ13C values for eight phytoplankton classes, five bacterial taxa, and three types of terrestrial organic matter (two trees and one grass). The lipid content was higher amongst the phytoplankton (…
Ģimenes ārstu nozīmētās H.Pylori eradikācijas shēmas, to atbilstība vadlīnijām, indikācijām un efektivitāte
2015
H.pylori ir patogēna baktērija, kas kolonizē kuņģa gļotādu. H.pylori eradikācija potenciāli var pasargāt no kuņģa vēža. Māstrihtas vadlīnijas IV nosaka, H.pylori eradikācijas terapiju veikt pacientiem ar noteiktām indikācijām. Pētījumā analizēta ģimenes ārstu nozīmēto eradikācijas terapijas kursu efektivitāte un tā atbilstība vadlīnijām. Analīzē izmantoti dati par 412 pacientiem, kuri ieradušies uz eradikācijas terapijas kursa kontroli. Analīze veikta gan pēc pirmreizēja, gan atkārtota eradikācijas kursa. Kopumā tika analizēti 427 eradikācijas terapijas kursi, 224 no tiem, bija ģimenes ārstu nozīmēti. Sekmīga ģimenes ārstu nozīmētā terapija bija 170 (75.9%) gadījumos, pirmreizēji nozīmētas …