Search results for "ASTER"
showing 10 items of 2223 documents
Entropy-controlled diastereoselectivity in the photocyclization of rigid derivatives of o-allylaniline.
2002
Two rigid derivatives of o-allylaniline, namely 8-allyl-2-phenyl-1,2,3,4-tetrahydroquinoline (1b) and 7-(trans-2-cinnamyl)-2-methylindoline (1c), have been chosen as suitable systems to study the potential stereoselectivity of the photocyclization process. Photolysis of 1b leads to a mixture of diastereomeric lilolidines 4 (trans/cis), while 1cproduces a mixture of 4 (trans/cis) and the tetrahydropyrrolo[3,2,1-hi]indole derivatives 5 (trans/cis). To disclose whether the diastereoselectivity could be entropy dependent, photolysis of 1b and 1c has been performed at several temperatures. In both cases, linear relationships have been observed when ln(k(t)/k(c)) (the relative reaction rate const…
Conduit dynamics and post explosion degassing on Stromboli: A combined UV camera and numerical modeling treatment.
2016
Abstract Recent gas flux measurements have shown that Strombolian explosions are often followed by periods of elevated flux, or “gas codas,” with durations of order a minute. Here we present UV camera data from 200 events recorded at Stromboli volcano to constrain the nature of these codas for the first time, providing estimates for combined explosion plus coda SO2 masses of ≈18–225 kg. Numerical simulations of gas slug ascent show that substantial proportions of the initial gas mass can be distributed into a train of “daughter bubbles” released from the base of the slug, which we suggest, generate the codas, on bursting at the surface. This process could also cause transitioning of slugs i…
Quality Model - Master Plan and DNA of an Information System
2012
Every theory has its surroundings and postulates. So has a theory about quality models, and it is better to make the main lines of these ideas explicit before presenting the theory itself. A human made information system (IS) as a technical artifact exists and operates always in the context of societies, organizations, personal lives etc. It is a tool used for gathering, storing, processing, presenting and exchanging (communication) information. These activities can be termed “information behavior” (Allen et al., 2011). Accordingly the context of an information system has a two-tiered structure (Figure 1). The inner tier, information behavior, is subordinate to the outer tier, human society…
Understanding the Health Disaster: Research Design for the Response to the 2014 West African Ebola Outbreak
2015
International audience; The 2014 Ebola outbreak in West Africa is the largest ever in history, affecting multiple countries and to this date, the World Health Organization has registered more than 6,500 deaths attributed to Ebola. The challenges arising from this outbreak to responders worldwide do not follow the standard characterisation or response patterns of natural sudden onset vs. conflict disasters. Rather, it is a medical emergency, which is intertwined with multiple challenges in the sectors decision-making, coordination, logistics and information management. In this paper, we present our research framework, which is based on desk research and initial interviews with responders. Th…
On the Nature of Information Management in Complex and Natural Disasters
2015
Abstract The purpose of this paper is to present reflections on the nature of information management (IM) and its role and function to support coordination in one of the largest humanitarian crises of our time, the Syria crisis. Starting from general principles for humanitarian information management, we analyze the challenges that information managers face in conflict situations, when information is – more than anywhere else – a source of power and influence. This work outlines the interdependence of advocacy and operational information management, the sensitivity of information, and barriers to information sharing. The results are complex and highly interlaced information and coordination…
Information transfer determined by association of neighbours in European bee-eater (Merops apiaster) colonies
2007
The Information Centre Hypothesis (ICH) and the Two-Strategies Hypothesis (TSH) predict that foraging success is enhanced by information exchanged among individuals within a colony or roost. Nest location within a colony may be critical in this regard, as individuals with abundant, nearby neighbours likely have greater access to information regarding a new food resource than relatively isolated breeders. To determine how the availability of neighbours influences information transfer, we quantified foraging success in a population of European bee-eaters (Merops apiaster) provided with a honey bee (Apis mellifera) hive as a new food resource. To quantify potential information transfer we deve…
Eines web per a l'elaboració del Treball Final de Grau i Màster en Enginyeria Química
2014
La necessitat d'un gran volum d'informació per a l'elaboració de projectes de caràcter professional en Enginyeria Química pot esdevenir un greu problema en aquells casos en els quals el projecte ha de ser preparat pels alumnes per al seu Treball Fi de Grau o Treball Fi de Màster, ja que la consecució d'aquesta informació és complicada i implica, en moltes ocasions, una despesa econòmica important. Per resoldre aquest problema, l'objectiu d'aquest article és subministrar a l'estudiant eines web de lliure accés que li permeten tenir informació relativa a les parts del projecte que ha d'elaborar. Per a fer-ho s'ha realitzat una anàlisi dels camps en els quals l'estudiant necessita informació i…
Rúbricas para la tutorización y (auto)evaluación de Trabajos Fin de Máster en el ámbito del desarrollo local y territorial
2015
[EN] The final project of the Master's Degree in Management and Promotion of Local Development reflects the plurality and multidisciplinary complexity of working in the field of territorial development where different approaches and professors come together, each one with their own scientific corpus and educational practice. In order to deal with this complexity, the design of a new evaluation model for this subject was seen as necessary. The idea was to guarantee transversal and simple criteria which were seen as valid under any academic perspective that values the students' work and learning in the theoretical and/or applied field of local development. The rubric proposed as result allows…
Synthesis and X-ray structure of metalated Rhodium(II) catalysts with a chiral phospholane
2001
The reaction of Rh2(O2CR)4 (R = CH3, CF3) with the chiral phosphane (2S,5S)-2,5-dimethyl-1-phenylphospholane (PC*H), results in the formation of two diastereoisomers of Rh2(O2CCR)2(PC*)2, with (P) and (M) configuration. These can easily be isolated by chromatographic methods to obtain enantiomerically pure RhII compounds. Preliminary catalytic studies have shown that they induce moderate asymmetry in the cyclization of 5-aryl-1-diazo-2-pentanones and 1-diazo-5-hexen-2-one. X-ray analysis of the (M) diastereoisomer with formula Rh2(O2CCCH3)2(PC*)2 is reported. The crystallographic parameters are as follows: space group P21212 (orthorhombic) with a = 12.1347(11) A, b = 14.5870(13) A, c = 9.81…
Di‐ and Trivalent Ytterbium Complexes Containing Linked Amino‐ and Amidocyclopentadienyl Ligands
2003
Reactions of the aminocyclopentadienes (C5Me4H)SiMe2NHR (R = Et, allyl, nPr, tBu) with [YbI2(THF)2] in the presence of two equivalents of potassium 1,2-diphenylethenide in THF at room temperature gave the diamagnetic half-sandwich complexes [Yb(η5-C5Me4SiMe2NHR)Ln(μ-I)]2 (L = THF, n = 2, L = DME, n = 1). The tert-butylamido derivative [Yb(η5-C5Me4SiMe2NHtBu)(THF)2(μ-I)]2 was characterized by X-ray structural analysis as a dinuclear complex containing a nonchelating aminocyclopentadienyl ligand. Deprotonation of the aminocyclopentadiene (C5H4tBu)SiMe2NHtBu with two equivalents of potassium 1,2-diphenylethenide in THF, followed by reaction with [YbI2(THF)2] at 60 °C, gave the trivalent ytterb…