Institution
Bielefeld University
Education•Bielefeld, Nordrhein-Westfalen, Germany•
About: Bielefeld University is a education organization based out in Bielefeld, Nordrhein-Westfalen, Germany. It is known for research contribution in the topics: Population & Quantum chromodynamics. The organization has 10123 authors who have published 26576 publications receiving 728250 citations. The organization is also known as: University of Bielefeld & UNIVERSITAET BIELEFELD.
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TL;DR: In this paper, the euclidean formulation of the thermodynamics for quantum spin systems was reviewed and the corresponding formalism for SU(N) gauge fields on the lattice.
186 citations
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TL;DR: A kinematic model of hexapod walking is described: the distributed artificial neural network controller walknet, which allows stable walking of the insect model as well as of a number of legged robots.
186 citations
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TL;DR: The photodissociation of water in the first absorption band, H{sub 2}O(X) + {Dirac_h}{omega} {yields} H[sub 2]O(A{sup 1}B{sub 1} + OH{sup 2}S] + OH[sup 2]II], is a prototype of fast and direct bond rupture in an excited electronic state.
Abstract: The photodissociation of water in the first absorption band, H{sub 2}O(X) + {Dirac_h}{omega} {yields} H{sub 2}O(A{sup 1}B{sub 1}) {yields} H({sup 2}S) + OH({sup 2}II), is a prototype of fast and direct bond rupture in an excited electronic state. It has been investigated from several perspectives-absorption spectrum, final state distributions of the products, dissociation of vibrationally excited states, isotope effects, and emission spectroscopy. The availability of a calculated potential energy surface for the A state, including all three internal degrees of freedom, allows comparison of all experimental data with the results of rigorous quantum mechanical calculations without any fitting parameters or simplifying model assumptions. As the result of the confluence of ab initio electronic structure theory, dynamical theory, and experiment, water is probably the best studied and best understood polyatomic photodissociation system. In this article we review the joint experimental and theoretical advances which make water a unique system for studying molecular dynamics in excited electronic states. We focus our attention especially on the interrelation between the various perspectives and the correlation with the characteristic features of the upper-state potential energy surface. 80 refs., 14 figs.
186 citations
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TL;DR: It is shown that the thermodynamic presence of these additional states gets imprinted in the yields of the ground-state strange hadrons leading to a systematic 5-8 MeV decrease of the chemical freeze-out temperatures of ground- state strange baryons.
Abstract: We compare lattice QCD results for appropriate combinations of net strangeness fluctuations and their correlations with net baryon number fluctuations with predictions from two hadron resonance gas (HRG) models having different strange hadron content. The conventionally used HRG model based on experimentally established strange hadrons fails to describe the lattice QCD results in the hadronic phase close to the QCD crossover. Supplementing the conventional HRG with additional, experimentally uncharted strange hadrons predicted by quark model calculations and observed in lattice QCD spectrum calculations leads to good descriptions of strange hadron thermodynamics below the QCD crossover. We show that the thermodynamic presence of these additional states gets imprinted in the yields of the ground-state strange hadrons leading to a systematic 5-8 MeV decrease of the chemical freeze-out temperatures of ground-state strange baryons.
186 citations
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Karlsruhe Institute of Technology1, Leibniz Association2, Goethe University Frankfurt3, Bielefeld University4, University of Mainz5, Max Planck Society6, ETH Zurich7, Colorado State University8, North Carolina State University9, Pacific Northwest National Laboratory10, University of Leeds11, Michigan Technological University12, Cooperative Institute for Research in Environmental Sciences13
TL;DR: In this paper, the authors compared the performance of 17 different immersion freezing measurements with respect to surface area-based and geometric surface-site-based ns(T) spectra and showed that the immersion freezing efficiency expressed in ns of illite-rich clay mineral particles is relatively independent of droplet size, particle mass in suspension, particle size and cooling rate during freezing.
Abstract: . Immersion freezing is the most relevant heterogeneous ice nucleation mechanism through which ice crystals are formed in mixed-phase clouds. In recent years, an increasing number of laboratory experiments utilizing a variety of instruments have examined immersion freezing activity of atmospherically relevant ice-nucleating particles. However, an intercomparison of these laboratory results is a difficult task because investigators have used different ice nucleation (IN) measurement methods to produce these results. A remaining challenge is to explore the sensitivity and accuracy of these techniques and to understand how the IN results are potentially influenced or biased by experimental parameters associated with these techniques. Within the framework of INUIT (Ice Nuclei Research Unit), we distributed an illite-rich sample (illite NX) as a representative surrogate for atmospheric mineral dust particles to investigators to perform immersion freezing experiments using different IN measurement methods and to obtain IN data as a function of particle concentration, temperature (T), cooling rate and nucleation time. A total of 17 measurement methods were involved in the data intercomparison. Experiments with seven instruments started with the test sample pre-suspended in water before cooling, while 10 other instruments employed water vapor condensation onto dry-dispersed particles followed by immersion freezing. The resulting comprehensive immersion freezing data set was evaluated using the ice nucleation active surface-site density, ns, to develop a representative ns(T) spectrum that spans a wide temperature range (−37 °C In general, the 17 immersion freezing measurement techniques deviate, within a range of about 8 °C in terms of temperature, by 3 orders of magnitude with respect to ns. In addition, we show evidence that the immersion freezing efficiency expressed in ns of illite NX particles is relatively independent of droplet size, particle mass in suspension, particle size and cooling rate during freezing. A strong temperature dependence and weak time and size dependence of the immersion freezing efficiency of illite-rich clay mineral particles enabled the ns parameterization solely as a function of temperature. We also characterized the ns(T) spectra and identified a section with a steep slope between −20 and −27 °C, where a large fraction of active sites of our test dust may trigger immersion freezing. This slope was followed by a region with a gentler slope at temperatures below −27 °C. While the agreement between different instruments was reasonable below ~ −27 °C, there seemed to be a different trend in the temperature-dependent ice nucleation activity from the suspension and dry-dispersed particle measurements for this mineral dust, in particular at higher temperatures. For instance, the ice nucleation activity expressed in ns was smaller for the average of the wet suspended samples and higher for the average of the dry-dispersed aerosol samples between about −27 and −18 °C. Only instruments making measurements with wet suspended samples were able to measure ice nucleation above −18 °C. A possible explanation for the deviation between −27 and −18 °C is discussed. Multiple exponential distribution fits in both linear and log space for both specific surface area-based ns(T) and geometric surface area-based ns(T) are provided. These new fits, constrained by using identical reference samples, will help to compare IN measurement methods that are not included in the present study and IN data from future IN instruments.
185 citations
Authors
Showing all 10375 results
Name | H-index | Papers | Citations |
---|---|---|---|
Stefan Grimme | 113 | 680 | 105087 |
Alfred Pühler | 102 | 658 | 45871 |
James Barber | 102 | 642 | 42397 |
Swagata Mukherjee | 101 | 1048 | 46234 |
Hans-Joachim Werner | 98 | 317 | 48508 |
Krzysztof Redlich | 98 | 609 | 32693 |
Graham C. Walker | 93 | 381 | 36875 |
Christian Meyer | 93 | 1081 | 38149 |
Muhammad Farooq | 92 | 1341 | 37533 |
Jean Willy Andre Cleymans | 90 | 542 | 27685 |
Bernhard T. Baune | 90 | 608 | 50706 |
Martin Wikelski | 89 | 420 | 25821 |
Niklas Luhmann | 85 | 421 | 42743 |
Achim Müller | 85 | 926 | 35874 |
Oliver T. Wolf | 83 | 337 | 24211 |