Supporting remote collaborative problem-solving
- We propose a framework of individual problem-solving and communicative demands (IproCo) that bridges the gap between models from cognitive psychology and communication pragmatics. Furthermore, we present two experiments conducted to identify factors influencing the demands and to test possibilities for support. The experiments employed a remote collaborative picture-sorting task with concrete and abstract pictures and applied non-interactive conditions compared to interactive conditions. In a first experiment, the influence of the postulated demands on collaboration process and outcome was analysed, and the impact of shared applications was tested. In a second experiment, we evaluated instructional support measures consisting of model collaboration and a collaboration script. The collaboration process showed benefits of the support but the outcome did not. However, the support measures fostered the collaboration process even in the particularly difficult conditions with non-interactive communication. We discuss the impact of the IproCo framework and apply it to other tasks.
Supporting and hindering knowledge communication in a collaborative picture-sorting task
- Effective knowledge communication presupposes common ground (Clark & Brennan, 1991) that needs to be established and maintained. This is particularly difficult in remote communication as well as in non-interactive settings, because the speaker cannot use gestures or mimic and has to tailor his utterances to the addressee without receiving feedback. In these situations, the speaker may achieve mutual understanding for example by adopting the addressee’s perspective. We present a study conducted to test the impact of instructions that support and hinder individual problem solving and knowledge communication. We used a picture-sorting task requiring individual cognitive processes of feature search (Treisman & Gelade, 1980) in addition to referential communication. As our study focused on the design of utterances, all participants assumed the role of speaker. Participants were told that their descriptions would be recorded and then listened to later on by a participant in the role of addressee. Eight sets of pictures were used, which varied on two dimensions: the individual cognitive demands of detecting the relevant features (varied as between-subject factor) and the communicative demands (varied as within-subject factor). A further between-subject factor was the type of instructions: The participants received either a collaboration script as supporting instructions, or time pressure was applied to induce stress, or else they were given no additional instructions (control group). We used the speakers’ verbal utterances to examine the quality of the speakers’ descriptions. For both dimensions of difficulty, we found the expected effects. In the conditions with a collaboration script, there were fewer irrelevant features mentioned and fewer features were described with delay. In the conditions with time pressure, there were fewer irrelevant features described, but the number of correctly described pictures was impaired through the fact that relevant features were also neglected. Under time pressure, speakers tended to provide ambiguous descriptions regarding the frame of reference.
Quantitative analysis of the cardiac fibroblast transcriptome implications for NO/cGMP signaling
Maisa I. Garcia Arguinzonis
Suzanne M. Lohmann
- Cardiac fibroblasts regulate tissue repair and remodeling in the heart. To quantify transcript levels in these cells we performed a comprehensive gene expression study using serial analysis of gene expression (SAGE). Among 110,169 sequenced tags we could identify 30,507 unique transcripts. A comparison of SAGE data from cardiac fibroblasts with data derived from total mouse heart revealed a number of fibroblast-specific genes. Cardiac fibroblasts expressed a specific collection of collagens, matrix proteins and metalloproteinases, growth factors, and components of signaling pathways. The NO/cGMP signaling pathway was represented by the mRNAs for α1 and β1 subunits of guanylyl cyclase, cGMP-dependent protein kinase type I (cGK I), and, interestingly, the G-kinase-anchoring protein GKAP42. The expression of cGK I was verified by RT-PCR and Western blot. To establish a functional role for cGK I in cardiac fibroblasts we studied its effect on cell proliferation. Selective activation of cGK I with a cGMP analog inhibited the proliferation of serum-stimulated cardiac fibroblasts, which express cGK I, but not higher passage fibroblasts, which contain no detectable cGK I. Currently, our data suggest that cGK I mediates the inhibitory effects of the NO/cGMP pathway on cardiac fibroblast growth. Furthermore the SAGE library of transcripts expressed in cardiac fibroblasts provides a basis for future investigations into the pathological regulatory mechanisms underlying cardiac fibrosis.
Endothelium-dependent and -independent relaxation and VASP serines 157/239 phosphorylation by cyclic nucleotide-elevating vasodilators in rat aorta
- Endothelium-dependent vasodilation is thought to be mediated primarily by the NO/cGMP signaling pathway whereas cAMP-elevating vasodilators are considered to act independent of the endothelial cell layer. However, recent functional data suggest that cAMP-elevating vasodilators such as β-receptor agonists, adenosine or forskolin may also be endothelium-dependent. Here we used functional and biochemical assays to analyze endothelium-dependent, cGMP- and cAMP-mediated signaling in rat aorta. Acetylcholine and sodium nitroprusside (SNP) induced a concentration-dependent relaxation of phenylephrine-precontracted aorta. This response was reflected by the phosphorylation of the vasodilator-stimulated phosphoprotein (VASP), a validated substrate of cGMP- and cAMP-dependent protein kinases (cGK, cAK), on Ser157 and Ser239. As expected, the effects of acetylcholine were endothelium-dependent. However, relaxation induced by the β-receptor agonist isoproterenol was also almost completely impaired after endothelial denudation. At the biochemical level, acetylcholine- and isoproterenol-evoked cGK and cAK activation, respectively, as measured by VASP Ser239 and Ser157 phosphorylation, was strongly diminished. Furthermore, the effects of isoproterenol were repressed by eNOS inhibition when endothelium was present. We also observed that the relaxing and biochemical effects of forskolin were at least partially endothelium-dependent. We conclude that cAMP-elevating vasodilators, i.e. isoproterenol and to a lesser extent also forskolin, induce vasodilation and concomitant cyclic nucleotide protein kinase activation in the vessel wall in an endothelium-dependent way.
The NO/cGMP pathway inhibits Rap1 activation in human platelets via cGMP-dependent protein kinase I
- The NO/cGMP signalling pathway strongly inhibits agonist-induced platelet aggregation. However, the molecular mechanisms involved are not completely defined.We have studied NO/cGMP effects on the activity of Rap1, an abundant guanine-nucleotidebinding protein in platelets. Rap1-GTP levels were reduced by NO-donors and activators of NO-sensitive soluble guanylyl cyclase. Four lines of evidence suggest that NO/cGMP effects are mediated by cGMP-dependent protein kinase (cGKI): (i) Rap1 inhibition correlated with cGKI activity as measured by the phosphorylation state ofVASP, an established substrate of cGKI, (ii) 8-pCPT-cGMP, a membrane permeable cGMP-analog and activator of cGKI, completely blocked Rap1 activation, (iii) Rp- 8pCPT-cGMPS, a cGKI inhibitor, reversed NO effects and (iv) expression of cGKI in cGKI-deficient megakaryocytes inhibited Rap1 activation. NO/cGMP/cGKI effects were independent of the type of stimulus used for Rap1 activation.Thrombin-,ADPand collagen-induced formation of Rap1-GTP in platelets as well as turbulence-induced Rap1 activation in megakaryocytes were inhibited. Furthermore, cGKI inhibited ADP-induced Rap1 activation induced by the G a i -coupled P2Y12 receptor alone, i.e. independently of effects on Ca2+-signalling. From these studies we conclude that NO/cGMP inhibit Rap1 activation in human platelets and that this effect is mediated by cGKI. Since Rap1 controls the function of integrin a IIbß 3 , we propose that Rap1 inhibition might play a central role in the anti-aggregatory actions of NO/cGMP.
[Rezension zu:] Gisela Brünner. 2011. Gesundheit durchs Fernsehen. Linguistische Untersuchungen zur Vermittlung medizinischen Wissens und Aufklärung in Gesundheitssendungen. Duisburg: Universitätsverlag Rhein-Ruhr. 528 S.
Nina Jeanette Hofferberth
David Sebastian Sauer
Verso il Danubio : La passeggiata di Thomas Bernhard
- Avventurarsi e poi inoltrarsi nell'opera di Thomas Bernhard non è precisamente come fare una passeggiata, ma la passeggiata è un motivo ricorrente nell'opera bernhardiana (insieme a quella di Handke, di Sebald, di Walser, per fare solo alcuni nomi di passeggiatori nel Novecento di lingua tedesca). Le figure di Bernhard camminano, marciano, corrono, ma in una "direzione opposta" rispetto a quella indicata da Stifter. Talvolta i loro percorsi si snodano nella natura, come quando entrano in un bosco per non fare più ritorno (Gelo, Al limite boschivo, La partita a carte), a volte marciano nel chiuso della loro "casa-prigione", seguendo i percorsi labirintici e infiniti della loro mente (La Fornace, Cemento), altre volte ancora si muovono in un contesto cittadino e metropolitano, a Roma in Estinzione (dove la passeggiata con l'allievo Gambetti conserva un alone aristotelico, il peripatetico) o - più spesso - a Vienna.
Dialettica negativa e Antropologia negativa : Adorno - Anders
- Un titolo quale "Dialettica negativa e antropologia negativa" sembrerebbe preannunciare un lavoro di confronto tra Th. W. Adorno e Ulrich Sonnemann, sulla scia di una indicazione mutuata dalla "Introduzione" di "Dialettica negativa" (1966). E invece, disattendendo una simile aspettativa, la "Negative Anthropologie" cui ci si riferisce in questo saggio è quella di Günther Stern/Anders. L’idea di un confronto tra le due prospettive nasce dalla curiosità di capire la corrispondenza tra la "dialettica negativa" e l'"antropologia negativa", laddove con il secondo sintagma si intende la concezione andersiana di un'umanità inadeguata al mondo. Che poi non si tratti di una stranezza ma di un interrogativo legittimo lo conferma, indirettamente, lo stesso Adorno, che in una nota contenuta nella sezione della "Dialettica negativa" dedicata alla lettura del pensiero di Heidegger, chiama in causa proprio la lezione di Anders.
Sestrin-2, a repressor of PDGFRβ signalling, promotes cigarette smoke-induced pulmonary emphysema in mice and is upregulated in patients with COPD
K. C. Kent Lloyd
Harald von Melchner
- Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide. COPD is caused by chronic exposure to cigarette smoke and/or other environmental pollutants that are believed to induce reactive oxygen species (ROS) that gradually disrupt signalling pathways responsible for maintaining lung integrity. Here we identify the antioxidant protein Sestrin 2 (Sesn2) as a repressor of PDGFRβ signalling and PDGFRβ signalling as an upstream regulator of alveolar maintenance programs. In mice, the mutational inactivation of Sesn2 prevents the development of cigarette-smoke induced pulmonary emphysema by upregulating PDGFRβ expression via a selective accumulation of intracellular superoxide anions (O2-). We also show that SESN2 is overexpressed and PDGFRβ downregulated in the emphysematous lungs of patients with COPD and to a lesser extent in human lungs of habitual smokers without COPD, implicating a negative SESN2/PDGFRβ interrelationship in the pathogenesis of COPD. Taken together, our results imply that SESN2 could serve as both a biomarker and as a drug target in the clinical management of COPD.
Integer point sets minimizing average pairwise L1 distance: What is the optimal shape of a town?
Erik D. Demaine
Sándor P. Fekete
- An n-town, n[is an element of]N , is a group of n buildings, each occupying a distinct position on a 2-dimensional integer grid. If we measure the distance between two buildings along the axis-parallel street grid, then an n-town has optimal shape if the sum of all pairwise Manhattan distances is minimized. This problem has been studied for cities, i.e., the limiting case of very large n. For cities, it is known that the optimal shape can be described by a differential equation, for which no closed-form solution is known. We show that optimal n-towns can be computed in O(n[superscript 7.5]) time. This is also practically useful, as it allows us to compute optimal solutions up to n=80.