Modeling charge transport in C60-based self-assembled monolayers for applications in field-effect transistors

We have investigated the conductance properties of C60-containing self-assembled monolayers (SAMs), which are used in organic field-effect transistors, employing a combination of molecular-dynamics simulations, semiempirical electronic structure calculations and Landauer transport theory. The results reveal the close relation between the transport characteristics and the structural and electronic properties of the SAM. Furthermore, both local pathways of charge transport in the SAMs and the influence of structural fluctuations are analyzed.Comment: 10 figure

Memory control ability modulates intrusive memories after analogue trauma

AbstractBackgroundMost people suffer from intrusive memories in the aftermath of trauma. For survivors' well-being, it is key that these intrusions are controlled. Memory control can be exerted through retrieval suppression. Poor retrieval suppression, however, should be associated with persistent distressing intrusions and posttraumatic stress disorder (PTSD). This study tested the hypothesis that individual differences in retrieval suppression predict intrusive memories after trauma. Retrieval suppression was examined with the think/no-think task (TNT) using behavioral and event related potential (ERP) measures.MethodsTwenty-four healthy participants watched a “traumatic” film after performing the TNT task. The frequency and distress of intrusions from the “traumatic” film was measured with an electronic diary. Additionally the Impact of Event Scale (IES) was assessed.ResultsIn line with our hypothesis, behavioral measures of retrieval suppression ability predicted reduced distress ratings for intrusions (r=−.53, p<.01). Further ERP markers of retrieval suppression (a fronto-centrally distributed N2) predicted reduced distress ratings for intrusions (r=−.45, p<.05) and reduced IES Intrusion scores (r=−.56, p<.01).LimitationsThe presented film is a relatively mild stressor as compared to a real-life trauma. Further studies are needed to explore the role of memory control processes for real-life trauma.ConclusionsParticipants with lower retrieval suppression ability exhibited less distressing intrusive memories after analogue trauma. The ERP correlate of retrieval suppression was associated with less distressing intrusive memories and reduced IES Intrusion scores, suggesting that deficient memory control is a potential risk factor for developing PTSD

Meta-Analyse programmatischer-präventiver Förderung der emotionalen und sozialen Entwicklung in der Primarstufe

Im Gegensatz zu klinischen Einrichtungen ist die Schule für alle Kinder und Jugendliche zugänglich, sodass sie das wichtigste Setting für präventive Maßnahmen im Bereich der emotionalen und sozialen Entwicklung ist. Internationale Studien bestätigen die Wirksamkeit schulischer präventiver Förderung. Bei der Übertragung dieser Befunde auf Schulen in Deutschland besteht jedoch das Problem, dass die Wirkung von Präventionsprogrammen nicht beliebig interkulturell übertragbar ist. Eine Überprüfung für das deutsche Schulsystem ist vor diesem Hintergrund indiziert. Ziel dieser Arbeit ist es, die Wirksamkeit manualisierter, deutschsprachiger Präventionsprogramme für den Einsatz in der Schule meta-analytisch zu erfassen, überblicksartig darzustellen und den Einfluss spezifischer Moderatoren auf die Programmeffekte zu überprüfen. Der Vergleich der Effekte der unterschiedlichen Studien erfolgt mittels Cohens d und der anschließenden Berechnung der mittleren gewichteten Effektstärke nach Wilson. Entlang der inhaltlichen und methodischen Einschlusskriterien konnten insgesamt zwölf Programme für die Primarstufe identifiziert werden. Zu diesen liegen zusammen 13 Studien mit insgesamt 169 Gruppenvergleichen vor. Im Prä-Post-Vergleich liegt die durchschnittliche Effektstärke bei dw=0.15. Für die Prä-Follow-up Analysen ergibt sich dw=0.23. Zudem konnten relevante Einflüsse der Erhebungsmethode (r=.22) und der Präventionsebene (r=.39) festgestellt werden. Auf Programmebene lassen sich die schrittweise Erarbeitung eines sozialen Problemlösezirkels (r=.31) und die Anzahl der Einheiten (r=.33) als relevante Einflussfaktoren für die Wirksamkeit herausstellen. Implikationen für das Fach emotionale und soziale Entwicklung werden diskutiert. (DIPF/Orig.

What determines the density structure of molecular clouds? A case study of Orion B with <i>Herschel</i>

A key parameter to the description of all star formation processes is the density structure of the gas. In this Letter, we make use of probability distribution functions (PDFs) of Herschel column density maps of Orion B, Aquila, and Polaris, obtained with the Herschel Gould Belt survey (HGBS). We aim to understand which physical processes influence the PDF shape, and with which signatures. The PDFs of Orion B (Aquila) show a lognormal distribution for low column densities until AV ~ 3 (6), and a power-law tail for high column densities, consistent with a ρα r-2 profile for the equivalent spherical density distribution. The PDF of Orion B is broadened by external compression due to the nearby OB stellar aggregates. The PDF of a quiescent subregion of the non-star-forming Polaris cloud is nearly lognormal, indicating that supersonic turbulence governs the density distribution. But we also observe a deviation from the lognormal shape at AV > 1 for a subregion in Polaris that includes a prominent filament. We conclude that (1) the point where the PDF deviates from the lognormal form does not trace a universal AV -threshold for star formation, (2) statistical density fluctuations, intermittency, and magnetic fields can cause excess from the lognormal PDF at an early cloud formation stage, (3) core formation and/or global collapse of filaments and a non-isothermal gas distribution lead to a power-law tail, and (4) external compression broadens the column density PDF, consistent with numerical simulations

TEACH-WELL. Psychische Gesundheit und Wohlbefinden im Klassenraum durch das Good Behavior Game (Team-oriented classroom intervention to support mental health and well being – TEACH-WELL)

Im Beitrag wird die TEACH-WELL Studie vorgestellt und das Design kritisch diskutiert. Es handelt sich um die Beschreibung eines Forschungsvorhabens, das sich derzeit noch in der Planungsphase befindet. TEACH-WELL möchte die vor allem in den USA, Belgien und den Niederlanden nachgewiesenen Effekte des Good Behavior Game (GBG) in der Grundschule replizieren. In Anlehnung an das Forschungsdesign des wissenschaftlichen Ausgangsprojekts von Leflot, van Lier, Onghena & Colpin (2010, 2013) wird ein Quasi-experimentelles Kontrollgruppendesign mit fünf Messzeitpunkten und insgesamt ca. 1.300 Grundschülerinnen und -schüler umgesetzt. Es ist davon auszugehen, dass sich durch den Einsatz des GBG unter anderem eine deutliche Verhaltensverbesserung der Schülerinnen und Schüler im Unterricht zeigt. (DIPF/Orig.

Uptake of triiodothyronine sulfate and suppression of thyrotropin secretion in cultured anterior pituitary cells

To investigate the uptake of triiodothyronine sulfate (T3S) and its effect on thyrotropin-releasing hormone (TRH)-induced thyrotropin (TSH) secretion, anterior pituitary cells were isolated from euthyroid rats and cultured for 3 days in medium containing 10% fetal calf serum. Incubation was performed at 37°C in medium containing 0.5% bovine serum albumin (BSA). Exposure of the pituitary cells to TRH (0.1 μmol/L) for 2 hours stimulated TSH secretion by 176%. This effect was reduced by approximately 45% after a 2-hour preincubation with T3 (0.001 to 1 μmol/L). A significant inhibitory effect of T3S on TRH-induced TSH release was only observed at a concentration of 1 μmol/L. The uptake of [125I]T3 after 1 hour of incubation was reduced by 40% ± 4% (P < .001) by simultaneous addition of 10 nmol/L unlabeled T3, whereas 1 μmol/L T3S was required to obtain a reduction of the [125I]T3 uptake by 34% ± 2% (P < .001). The amount of T3 present in the unlabeled T3S preparation was 0.25% as determined by radioimmunoassay. When pituitary cells were incubated for 1 hour with [125I]T3S or [125I]T3 both 50,000 cpm/0.25 mL), the uptake of [125I]T3zS expressed as a percentage of the dose was 0.04% ± 0.02% (mean ± SE, n = 4), whereas that of [125I]T3 amounted to 3.0% ± 0.4% (n = 4). In contrast, when hepatocytes were incubated for 1 hour with [125I]T3S, the uptake amounted to 5.1% ± 0.8% (n = 9), whereas that of [125I]T3 was 22.1% ± 1.7% (n = 9). Furthermore, [125I]T3S was as rapidly deiodinated (iodide production, 14.9% ± 2.6%; n = 9) as [125I]T3 (12.1% ± 0.8%, n = 9) by hepatocytes. It is concluded that (1) T3S is poorly taken up by pituitary cells, and (2) the suppressive effect of high concentrations of T3S on TRH-induced TSH secretion and on [125I]T3 uptake can be explained by slight contamination with T3. Thus, it appears that T3S has only a minor biological effect, if any, on the pituitary

Cluster-formation in the Rosette molecular cloud at the junctions of filaments

For many years feedback processes generated by OB-stars in molecular clouds, including expanding ionization fronts, stellar winds, or UV-radiation, have been proposed to trigger subsequent star formation. However, hydrodynamic models including radiation and gravity show that UV-illumination has little or no impact on the global dynamical evolution of the cloud. The Rosette molecular cloud, irradiated by the NGC2244 cluster, is a template region for triggered star-formation, and we investigated its spatial and density structure by applying a curvelet analysis, a filament-tracing algorithm (DisPerSE), and probability density functions (PDFs) on Herschel column density maps, obtained within the HOBYS key program. The analysis reveals not only the filamentary structure of the cloud but also that all known infrared clusters except one lie at junctions of filaments, as predicted by turbulence simulations. The PDFs of sub-regions in the cloud show systematic differences. The two UV-exposed regions have a double-peaked PDF we interprete as caused by shock compression. The deviations of the PDF from the log-normal shape typically associated with low- and high-mass star-forming regions at Av~3-4m and 8-10m, respectively, are found here within the very same cloud. This shows that there is no fundamental difference in the density structure of low- and high-mass star-forming regions. We conclude that star-formation in Rosette - and probably in high-mass star-forming clouds in general - is not globally triggered by the impact of UV-radiation. Moreover, star formation takes place in filaments that arose from the primordial turbulent structure built up during the formation of the cloud. Clusters form at filament mergers, but star formation can be locally induced in the direct interaction zone between an expanding HII--region and the molecular cloud.Comment: A&A Letter, in pres

The Herschel view of the on-going star formation in the Vela-C molecular cloud

As part of the Herschel guaranteed time key program 'HOBYS', we present the photometric survey of the star forming region Vela-C, one of the nearest sites of low-to-high-mass star formation in the Galactic plane. Vela-C has been observed with PACS and SPIRE in parallel mode between 70 um and 500 um over an area of about 3 square degrees. A photometric catalogue has been extracted from the detections in each band, using a threshold of 5 sigma over the local background. Out of this catalogue we have selected a robust sub-sample of 268 sources, of which 75% are cloud clumps and 25% are cores. Their Spectral Energy Distributions (SEDs) have been fitted with a modified black body function. We classify 48 sources as protostellar and 218 as starless. For two further sources, we do not provide a secure classification, but suggest they are Class 0 protostars. From SED fitting we have derived key physical parameters. Protostellar sources are in general warmer and more compact than starless sources. Both these evidences can be ascribed to the presence of an internal source(s) of moderate heating, which also causes a temperature gradient and hence a more peaked intensity distribution. Moreover, the reduced dimensions of protostellar sources may indicate that they will not fragment further. A virial analysis of the starless sources gives an upper limit of 90% for the sources gravitationally bound and therefore prestellar. We fit a power law N(logM) prop M^-1.1 to the linear portion of the mass distribution of prestellar sources. This is in between that typical of CO clumps and those of cores in nearby star-forming regions. We interpret this as a result of the inhomogeneity of our sample, which is composed of comparable fractions of clumps and cores.Comment: 9 pages, 7 figures, accepted by A&

Herschel Observations of a Potential Core Forming Clump: Perseus B1-E

We present continuum observations of the Perseus B1-E region from the Herschel Gould Belt Survey. These Herschel data reveal a loose grouping of substructures at 160 - 500 micron not seen in previous submillimetre observations. We measure temperature and column density from these data and select the nine densest and coolest substructures for follow-up spectral line observations with the Green Bank Telescope. We find that the B1-E clump has a mass of ~ 100 solar masses and appears to be gravitationally bound. Furthermore, of the nine substructures examined here, one substructure (B1-E2) appears to be itself bound. The substructures are typically less than a Jeans length from their nearest neighbour and thus, may interact on a timescale of ~ 1 Myr. We propose that B1-E may be forming a first generation of dense cores, which could provide important constraints on the initial conditions of prestellar core formation. Our results suggest that B1-E may be influenced by a strong, localized magnetic field, but further observations are still required.Comment: 14 pages, 8 figures, published in A&A: Minor calibration correctio

A <i>Herschel</i> and BIMA study of the sequential star formation near the W 48A H II region

We present the results of Herschel HOBYS (Herschel imaging survey of OB Young Stellar objects) photometric mapping combined with Berkeley Illinois Maryland Association (BIMA) observations and additional archival data, and perform an in-depth study of the evolutionary phases of the star-forming clumps in W 48A and their surroundings. Age estimates for the compact sources were derived from bolometric luminosities and envelope masses, which were obtained from the dust continuum emission, and agree within an order of magnitude with age estimates from molecular line and radio data. The clumps in W 48A are linearly aligned by age (east-old to west-young): we find a ultra-compact (UC) H II region, a young stellar object (YSO) with class II methanol maser emission, a YSO with a massive outflow and finally the NH2D prestellar cores from Pillai et al. This remarkable positioning reflects the (star) formation history of the region. We find that it is unlikely that the star formation in the W 48A molecular cloud was triggered by the UC H II region and discuss the Aquila supershell expansion as a major influence on the evolution of W 48A. We conclude that the combination of Herschel continuum data with interferometric molecular line and radio continuum data is important to derive trustworthy age estimates and interpret the origin of large-scale structures through kinematic information