Surface-structure libraries: multifrequential oscillations in catalytic hydrogen oxidation on rhodium

Multifrequential oscillating spatiotemporal patterns in the catalytic hydrogen oxidation on rhodium have been observed in situ in the 10 -6 mbar pressure range using photoemission electron microscopy. The effect is manifested by periodic chemical waves, which travel over the polycrystalline Rh surface and change their oscillation frequency while crossing boundaries between different Rh(hkl) domains. Each crystallographically specific μm-sized Rh(hkl) domain exhibits an individual wave pattern and oscillation frequency, despite the global diffusional coupling of the surface reaction, altogether creating a structure library. This unique reaction behavior is attributed to the ability of stepped surfaces of high-Miller-index domains to facilitate the formation of subsurface oxygen, serving as a feedback mechanism of kinetic oscillations. Formation of a network of subsurface oxygen as a result of colliding reaction fronts was observed in situ. Microkinetic model analysis was used to rationalize the observed effects and to reveal the relation between the barriers for surface oxidation and oscillation frequency. Structural limits of the oscillations, the existence range of oscillations, as well as the effect of varying hydrogen pressure are demonstrated

Visualizing catalyst heterogeneity by a multifrequencial oscillating reaction

It is well documented that different surface structures of catalytically active metals may exhibit different catalytic properties. This is typically examined by comparing the catalytic activities and/or selectivities of various well-defined smooth and stepped/kinked single crystal surfaces. Here we report the direct observation of the heterogeneity of active polycrystalline surfaces under reaction conditions, which is manifested by multifrequential\ua0oscillations during hydrogen oxidation over rhodium, imaged in situ by photoemission electron microscopy. Each specific surface structure, i.e. the crystallographically different \ub5m-sized domains of rhodium, exhibits an individual spiral pattern and oscillation frequency, despite the global diffusional coupling of the surface reaction. This reaction behavior is attributed to the ability of stepped surfaces of high-Miller-index domains to facilitate the formation of subsurface oxygen, serving as feedback mechanism of the observed oscillations. The current experimental findings, backed by microkinetic modeling, may open an alternative approach towards addressing the structure-sensitivity of heterogeneous surfaces

HDAC4-regulated STAT1 activation mediates platinum resistance in ovarian cancer

Ovarian cancer frequently acquires resistance to platinum chemotherapy, representing a major challenge for improving patient survival. Recent work suggests resistant clones exist within a larger drug sensitive cell-population prior to chemotherapy, implying that resistance is selected for rather than generated by treatment. We sought to compare clinically-derived, intra-patient paired models of initial platinum response and subsequent resistant relapse to define molecular determinants of evolved resistance. Transcriptional analysis of a matched cell-line series from three patients with high-grade serous ovarian cancer before and after development of clinical platinum resistance (PEO1/PEO4/PEO6, PEA1/PEA2, PEO14/PEO23) identified 91 up- and 126 down-regulated genes common to acquired resistance. Significantly enhanced apoptotic response to platinum treatment in resistant cells was observed following knockdown of HDAC4, FOLR2, PIK3R1 or STAT1 (p<0.05). Interestingly, HDAC4 and STAT1 were found to physically interact. Acetyl-STAT1 was detected in platinum sensitive but not HDAC4 over-expressing platinum resistant cells from the same patient. In resistant cells, STAT1 phosphorylation/nuclear translocation was seen following platinum exposure, whereas silencing of HDAC4 increased acetyl-STAT1 levels, prevented platinum induced STAT1 activation and restored cisplatin sensitivity. Conversely, matched sensitive cells were refractory to STAT1 phosphorylation on platinum treatment. Analysis of 16 paired tumor biopsies taken before and after development of clinical platinum resistance showed significantly increased HDAC4 expression in resistant tumors (n=7/16[44%]; p=0.04). Therefore, clinical selection of HDAC4 overexpressing tumor cells upon exposure to chemotherapy promotes STAT1 deacetylation and cancer cell survival. Together, our findings identify HDAC4 as a novel, therapeutically tractable target to counter platinum resistance in ovarian cancer

Cultural Diversity and Saccade Similarities: Culture Does Not Explain Saccade Latency Differences between Chinese and Caucasian Participants

A central claim of cultural neuroscience is that the culture to which an individual belongs plays a key role in shaping basic cognitive processes and behaviours, including eye movement behaviour. We previously reported a robust difference in saccade behaviour between Chinese and Caucasian participants; Chinese participants are much more likely to execute low latency express saccades, in circumstances in which these are normally discouraged. To assess the extent to which this is the product of culture we compared a group of 70 Chinese overseas students (whose primary cultural exposure was that of mainland China), a group of 45 participants whose parents were Chinese but who themselves were brought up in the UK (whose primary cultural exposure was western European) and a group of 70 Caucasian participants. Results from the Schwartz Value Survey confirmed that the UK-Chinese group were culturally similar to the Caucasian group. However, their patterns of saccade latency were identical to the mainland Chinese group, and different to the Caucasian group. We conclude that at least for the relatively simple reflexive saccade behaviour we have investigated, culture cannot explain the observed differences in behaviour

London calling?: Preferred emigration destinations among Icelandic youth

Post-print (lokagerð höfundar)Preferred emigration destinations among adolescents reflect images and stereotypes of other countries that continuously emerge in a multitude of local and global discourses and from concrete experiences with other countries. The affinities of Icelandic adolescents are split between the islands of the Northern Atlantic, continental Nordic countries, European core countries, and North American countries. If they had to leave Iceland, however, the largest proportion of Icelandic adolescents would want to move to the United States. Girls are more likely to choose the Nordic countries, in particular Denmark, while boys are more likely to choose English-speaking countries with a reputation for economic and military power such as the United States and England. Adolescents are more likely to prefer migrating to Europe rather than North America if they are proud of their Icelandic nationality, live in cohesive communities, have more educated parents, and feel closer to Europe. Adolescents who want to move abroad are in contrast most likely to have North American destinations in mind. Recent geopolitical changes may however shift the attention of Icelandic adolescents eastward towards the European continent.This article has benefited greatly from extensive discussions with Atli Hafthorsson, Brynhildur Thorarinsdottir, Kjartan Olafsson and Michael S. Gibbons, and from the pioneering scholarship of Professor Thorbjorn Broddason. The data collection was in part made possible by a grant from the University of Akureyri Research Fund.Peer Reviewe

Methodische Aspekte professionellen Handelns in Pädagogik und Sozialer Arbeit

Der Beitrag thematisiert die Komplexität des professionellen Handelns in der Pädagogik und der sozialen Arbeit, wobei die methodischen Zugänge und Reflexionshilfen im Mittelpunkt der Betrachtungen stehen. Im ersten Teil wird das Verhältnis von Subjekt und Ort in den beiden Feldern beleuchtet. Der Zusammenhang von Subjekt und Ort verweist darauf, dass es eine „wichtige professionelle Aufgabe ist, institutionelle Räume zu schaffen, die den Prinzipien der Prävention, der Integration und der Partizipation verpflichtet sind und in denen die individuellen Verfasstheiten der Individuen berücksichtigt werden.“ Teil 2 beschäftigt sich mit der Triangulierung und Virtualisierung in institutionellen und intersubjektiven Kontexten. Dabei werden die nicht immer konfliktfreien Verständigungsprozesse zwischen den Adressaten und den Professionellen in den Vordergrund gestellt. In Teil 3 werden die reziproke Anerkennung und die Dreiheit von Bildung, Erziehung und Betreuung hervorgehoben. Abschließend wird in Teil 4 auf die psychoanalytisch-pädagogische Reflexion in der Pädagogik und der sozialen Arbeit eingegangen. (DIPF/Bal