Search results for "RINGS"
showing 10 items of 434 documents
Augsnes un veģetācijas izmaiņas piesārņojuma dēļ Rīgas pilsētas mežos
2017
Pilsētas vides piesārņojumu var novērtēt dažādos veidos un viens no visbiežāk izmantotajiem ir sūnu biomonitorings. Līdz šim vēl nav atklāti un noskaidroti vienoti standarti par sūnu biomonitoringa efektīvāku izmantošanu. Nav arī vienota pētījuma par augsnes piesārņojuma ietekmi uz augu sugu daudzveidību. Pētījuma mērķis ir noskaidrot pilsētas vides piesārņotības pakāpes izvērtējumu, izmantojot sūnas un augsni kā bioindikatorus, un noteikt augu sugu daudzveidību atkarībā no augsnes piesārņojuma. Sphagnum sūnu sastāvā esošās smago metālu augstās koncentrācijas norāda, ka lielākais vides piesārņojums atrodams ceļa malās ar intensīvu satiksmi vai rūpnīcu, ostu tuvumā. Smago metālu piesārņojums…
MR 3020148 Reviewed McMullen, C.T. Braid groups and Hodge theory. Mathematische Annalen, vol. 355 (2013), pp.893–-946. (Reviewer Francesca Vetro) 20F…
2014
In this paper, the author studies the unitary representations of the braid group and the geometric structures on moduli space that arise via the Hodge theory of cyclic branched coverings of P^1. In particular, the author is interested in the classification of certain arithmetic subgroups of U(r, s) which envelop the image of the braid group. The author investigates their connections with complex reflection groups, Teichm\"{u}lller curves, ergodic theory and problems in surface topology.
Synthesis of Lamellarin D Trimethyl Ether and Lamellarin H via 6π-Electrocyclization.
2015
An electrocyclic ring closure of a 2-azapentadienyl anion generated in situ from a chalcone and glycine ester is the key step of an efficient synthesis of the pyrrole core of the lamellarin alkaloids. A recently developed scalable one-pot procedure provides multigram quantities of a 3,5-diaryl-4-iodopyrrole-2-carboxylate intermediate which is transformed in four further high-yielding operations including a one-pot Pomeranz–Fritsch alkylation/cyclization and an Ullmann-type lactone ring closure into the pentacyclic lamellarin skeleton.
Long-term decrease in Asian monsoon rainfall and abrupt climate change events over the past 6,700 years
2021
Significance The variability of the Asian summer monsoon (ASM) is important for the functioning of ecological and societal systems at regional to continental scales, but the long-term evolution and interannual variability of this system is not well understood. Here, we present a stable isotope–based reconstruction of ASM variability covering 4680 BCE to 2011 CE. Superimposed on a gradual drying trend, a rapid drop in mean annual precipitation (>40%) toward persistently drier conditions occurred in ∼1675 BCE. This megadrought caused regional forest deterioration and enhanced aeolian activity affecting Chinese ecosystems. We argue that this abrupt aridification starting ∼2000 BCE triggered wa…
Contact formation in random networks of elongated objects
2014
The effect of steric hindrance is an important aspect of granular packings as it gives rise to, e.g., limitations on the densities of ordered and disordered packings, both of which are essentially defined by the geometry of the constituents. Here we focus on random packing of rods via deposition and their distributions of contact number and segment length. Such statistical properties are relevant for mechanical properties of the structures, but the (quite large) steric effects on them have not been addressed in previous studies. We therefore develop a theory that describes the statistical properties of rod packings, while taking into account that the deposited rods cannot overlap and thus i…
Multiple origins of methane in fluids circulating in the Othrys ophiolite, central Greece
2018
The complex geology of Greece includes two important parallel running ophiolitic belts. The Othrys Massif in central Greece belongs to westernmost of them. In and around this wide ophiolite outcrop, some cold hyperalkaline and some hypothermal (T < 40°C) alkaline springs are present. Thirty water samples were collected at 17 different sites and both bubbling and dissolved gases were analysed for their chemical (He, Ne, H2, O2, N2, CH4, C2H6, CO2 and H2S) and isotope (He, δ13C-CO2, δ 13C-CH4, δ 2H-CH4) composition. All samples except one have H2S contents below detection limit (10 μmol/mol), whilst H2 (from <2 to 2500 μmol/mol), CO2 (up to 26,000 but generally below 1000 μmol/mol) and …
Crystal structure of 1-(2-fluorobenzoyl)-2,7-dimethoxynaphthalene
2014
The asymmetric unit of the compound contains two independent conformers. Each conformer is stacked along the a axis to form columns through van der Waals interactions only.
IDS sistēmas ieviešana augstas veiktspējas tīklu drošības monitoringam ar atvērtā pirmkoda rīkiem un patēriņa aparatūru
2019
Darba mērķis ir izpētīt, kā izmantot atvērtā pirmkoda IDS sistēmas ar patēriņa aparatūru, lai monitorētu drošību augstas veiktspējas tīklos, kuros tīkla caurlaidība pārsniedz 10Gbit/s. Lai parādītu, kāds ir veiktspējas ieguvums no dažādām ar veiktspēju saistītam izmaiņām IDS sistēmā, mērķis ir veikt sistēmas ieviešanu, kur tiek veiktas izmaiņas pa posmiem un tiek iegūti rezultāti par izmaiņām veiktspējas rādītājos. Darbā tika pētīti ar IDS sistēmas veiktspējas uzlabošanu saistīti akadēmiskie darbi, lai apkopotu tajās izmantotās metodes, kas ir palīdzējušas sasniegt augstus IDS sistēmas veiktspējas rādītājus. Darba praktiskajā daļā tika ieviests pakešu ģenerators IDS sistēmas veiktspējas tes…
Profesjonsfaglig digital kompetanse blant norsklærere : En kvalitativ studie som undersøker hvordan norsklærere på mellomtrinnet tilrettelegger for e…
2019
Masteroppgave grunnskolelærerutdanning trinn 1-7 NO502 - Universitetet i Agder 2019 The purpose of this thesis wasto investigate primary school teachers (grades 5-7) and their professional digital competence in the Norwegian subject. The research was based on the question: How do teachers arrange for a digital didactic in the Norwegian subject as a result of their professional digital competence?Through a phenomenologicalstudy, it wasan aim to try to understand twelve teachersstatements about what it means forteachersofNorwegian to have professional digital competence. The study also aimedto gain insight into how teachers create design for learning in digital environments using digital tool…
Too close for comfort? The impact of salesperson‐customer proximity on consumers' purchase behavior
2021
Across a series of lab and field studies, with a total sample of over 1200 participants, we investigate how the physical proximity between salespeople and customers can impact store loyalty, purchase intentions, and actual spending. An initial survey among a representative sample of retail salespeople reveals that they associate close physical proximity between employees and customers with positive consumer outcomes, an intuition that dovetails with prior research documenting the positive influence of such proximity on purchase intentions, particularly in nonexpressive consumption contexts. Contrary to this work, we demonstrate, across four studies in which proximity was both measured and m…