University of Potsdam

About: University of Potsdam is a education organization based out in Potsdam, Germany. It is known for research contribution in the topics: Population & Computer science. The organization has 9629 authors who have published 26740 publications receiving 759745 citations. The organization is also known as: Universität Potsdam.

Long-Term Relations Among Prosocial-Media Use, Empathy, and Prosocial Behavior

Abstract: Despite recent growth of research on the effects of prosocial media, processes underlying these effects are not well understood Two studies explored theoretically relevant mediators and moderators of the effects of prosocial media on helping Study 1 examined associations among prosocial- and violent-media use, empathy, and helping in samples from seven countries Prosocial-media use was positively associated with helping This effect was mediated by empathy and was similar across cultures Study 2 explored longitudinal relations among prosocial-video-game use, violent-video-game use, empathy, and helping in a large sample of Singaporean children and adolescents measured three times across 2 years Path analyses showed significant longitudinal effects of prosocial- and violent-video-game use on prosocial behavior through empathy Latent-growth-curve modeling for the 2-year period revealed that change in video-game use significantly affected change in helping, and that this relationship was mediated by change in empathy

Probing the transition state region in catalytic CO oxidation on Ru

Abstract: Femtosecond x-ray laser pulses are used to probe the carbon monoxide (CO) oxidation reaction on ruthenium (Ru) initiated by an optical laser pulse. On a time scale of a few hundred femtoseconds, the optical laser pulse excites motions of CO and oxygen (O) on the surface, allowing the reactants to collide, and, with a transient close to a picosecond (ps), new electronic states appear in the OK-edge x-ray absorption spectrum. Density functional theory calculations indicate that these result from changes in the adsorption site and bond formation between CO and O with a distribution of OC-O bond lengths close to the transition state (TS). After 1 ps, 10% of the CO populate the TS region, which is consistent with predictions based on a quantum oscillator model.

Uplift, exhumation and precipitation: tectonic and climatic control of Late Cenozoic landscape evolution in the northern Sierras Pampeanas, Argentina

Abstract: Deciphering the evolution of mountain belts requires information on the temporal history of both topographic growth and erosion The exhumation rate of a mountain range undergoing shortening is related to the erodability of the uplifting range as well as the efficiency of erosion, which partly depends on the available precipitation Young, rapidly deposited sediments have low thermal conductivity and are readily eroded, in contrast to underlying resistant basement rocks that have a higher thermal conductivity Apatite fission‐track thermochronology can quantify cooling; thermal models constrain the relationship between this cooling and exhumation By utilizing geological relations for a datum, we can examine the evolution of rock uplift, surface uplift and exhumation In the northern Sierras Pampeanas of Argentina, a young sedimentary basin that overlay resistant crystalline basement prior to rapid exhumation provides an ideal setting to examine the effect of contrasting thermal and erosional regimes There, tectonically active reverse‐fault‐bounded blocks partly preserve a basement peneplain at elevations in excess of 4500 m Prior to exhumation, the two study areas were covered by 1000 and 1600 m of recently deposited sediments; this sequence begins with shallow marine deposits immediately overlying the regional erosion surface Apatite fission‐track data were obtained from vertical transects in the Calchaquies and Aconquija ranges At Cumbres Calchaquies, erosion leading to the development of the peneplain commenced in the Cretaceous, probably as a result of rift‐shoulder uplift In contrast, Sierra Aconquija cooled rapidly between 55 and 45 Myr At the onset of this rapid exhumation, the sediment was quickly removed, causing fast cooling, but relatively slow rates of surface uplift Syntectonic conglomerates were produced when faulting exposed resistant bedrock; this change in rock erodability led to enhanced surface uplift rates, but decreased exhumation rates The creation of an orographic barrier after the range had attained sufficient elevation further decreased exhumation rates and increased surface uplift rates Differences in the magnitude of exhumation at the two transects are related to both differences in the thickness of the sedimentary basin prior to exhumation and differences in the effective precipitation due to an orographic barrier in the foreland and hence differences in the magnitude of headward erosion

Real-Time Observation of Surface Bond Breaking with an X-ray Laser

Abstract: We used the Linac Coherent Light Source free-electron x-ray laser to probe the electronic structure of CO molecules as their chemisorption state on Ru(0001) changes upon exciting the substrate by using a femtosecond optical laser pulse. We observed electronic structure changes that are consistent with a weakening of the CO interaction with the substrate but without notable desorption. A large fraction of the molecules (30%) was trapped in a transient precursor state that would precede desorption. We calculated the free energy of the molecule as a function of the desorption reaction coordinate using density functional theory, including van der Waals interactions. Two distinct adsorption wells—chemisorbed and precursor state separated by an entropy barrier—explain the anomalously high prefactors often observed in desorption of molecules from metals.

Ice plug prevents irreversible discharge from East Antarctica

Abstract: The Wilkes ice sheet in East Antarctica, which lies on bedrock below sea level, is sensitive to climate change but its stability and potential contribution to sea-level rise has not been comprehensively assessed. This study uses topographic data and ice-dynamic simulations to show that removal of a specific coastal ice volume destabilizes the ice sheet, leading to discharge of the entire Wilkes Basin and global sea-level rise of 3–4 m.