Continuum Singularities of a Mean Field Theory of Collisions

Consider a complex energy $z$ for a $N$-particle Hamiltonian $H$ and let $\chi$ be any wave packet accounting for any channel flux. The time independent mean field (TIMF) approximation of the inhomogeneous, linear equation $(z-H)|\Psi>=|\chi>$ consists in replacing $\Psi$ by a product or Slater determinant $\phi$ of single particle states $\phi_i.$ This results, under the Schwinger variational principle, into self consistent TIMF equations $(\eta_i-h_i)|\phi_i>=|\chi_i>$ in single particle space. The method is a generalization of the Hartree-Fock (HF) replacement of the $N$-body homogeneous linear equation $(E-H)|\Psi>=0$ by single particle HF diagonalizations $(e_i-h_i)|\phi_i>=0.$ We show how, despite strong nonlinearities in this mean field method, threshold singularities of the {\it inhomogeneous} TIMF equations are linked to solutions of the {\it homogeneous} HF equations.Comment: 21 pages, 14 figure

Histamine release after intravenous application of short-acting hypnotics. A comparison of etomidate, Althesin (CT1341) and propanidid

The subject of histamine release was investigated in 16 volunteers by means of plasma histamine determination after the administration of etornidate, Althesin, propanidid, and Cremophor EL. Althesin and propanidid caused release of histamine in various degrees of frequency. Blood pressure changes were rather pronounced with both anaesthetic agents; tachycardia reached its maximum in the first and second minute, which seems to be an argument against histamine release as the underlying cause of this reaction. Histamine was, indeed, only released to such an extent (with the exception of one borderline case) that no clinical symptoms other than secretion of gastric juice and erythema were to be expected. After the application of etomidate and Cremophor EL an increase in plasma histamine was not detectable. Changes in the differential blood picture in terms of a decrease in basophils only occurred after Althesin and propanidid; not, however, after etomidate and Cremophor EL. Etomidate is, therefore, the first hypnotic drug for intravenous application which is unlikely to cause chemical histamine release

Content-aware Traffic Engineering

Also appears as TU-Berlin technical report 2012-3, ISSN: 1436-9915Also appears as TU-Berlin technical report 2012-3, ISSN: 1436-9915Today, a large fraction of Internet traffic is originated by Content Providers (CPs) such as content distribution networks and hyper-giants. To cope with the increasing demand for content, CPs deploy massively distributed infrastructures. This poses new challenges for CPs as they have to dynamically map end-users to appropriate servers, without being fully aware of network conditions within an ISP as well as the end-users network locations. Furthermore, ISPs struggle to cope with rapid traffic shifts caused by the dynamic server selection process of CPs. In this paper, we argue that the challenges that CPs and ISPs face separately today can be turned into an opportunity. We show how they can jointly take advantage of the deployed distributed infrastructures to improve their operation and end-user performance. We propose Content-aware Traffic Engineering (CaTE), which dynamically adapts the traffic demand for content hosted on CPs by utilizing ISP network information and end-user location during the server selection process. As a result, CPs enhance their end-user to server mapping and improve end-user experience, thanks to the ability of network-informed server selection to circumvent network bottlenecks. In addition, ISPs gain the ability to partially influence the traffic demands in their networks. Our results with operational data show improvements in path length and delay between end-user and the assigned CP server, network wide traffic reduction of up to 15%, and a decrease in ISP link utilization of up to 40% when applying CaTE to traffic delivered by a small number of major CPs

Dynamics of Electron Localization in Warm vs. Cold Water Clusters

The process of electron localization on a cluster of 32 water molecules at 20, 50, and 300~K is unraveled using ab initio molecular dynamics simulations. In warm, liquid clusters, the excess electron relaxes from an initial diffuse and weakly bound structure to an equilibrated, strongly bound species within 1.5 ps. In contrast, on cold, glassy clusters the relaxation processes is not completed and the electron becomes trapped in a metastable surface state with an intermediate binding energy. These results question the validity of extrapolations of the properties of solvated electrons from cold clusters of increasing size to the liquid bulk

Methane-Oxidizing Seawater Microbial Communities from an Arctic Shelf

Marine microbial communities can consume dissolved methane before it can escape to the atmosphere and contribute to global warming. Seawater over the shallow Arctic shelf is characterized by excess methane compared to atmospheric equilibrium. This methane originates in sediment, permafrost, and hydrate. Particularly high concentrations are found beneath sea ice. We studied the structure and methane oxidation potential of the microbial communities from seawater collected close to Utqiagvik, Alaska, in April 2016. The in situ methane concentrations were 16.3 ± 7.2 nmol L−1 , approximately 4.8 times oversaturated relative to atmospheric equilibrium. The group of methaneoxidizing bacteria (MOB) in the natural seawater and incubated seawater was \u3e 97 % dominated by Methylococcales (γ -Proteobacteria). Incubations of seawater under a range of methane concentrations led to loss of diversity in the bacterial community. The abundance of MOB was low with maximal fractions of 2.5 % at 200 times elevated methane concentration, while sequence reads of non-MOB methylotrophs were 4 times more abundant than MOB in most incubations. The abundances of MOB as well as non-MOB methylotroph sequences correlated tightly with the rate constant (kox) for methane oxidation, indicating that non-MOB methylotrophs might be coupled to MOB and involved in community methane oxidation. In sea ice, where methane concentrations of 82 ± 35.8 nmol kg−1 were found, Methylobacterium (α-Proteobacteria) was the dominant MOB with a relative abundance of 80 %. Total MOB abundances were very low in sea ice, with maximal fractions found at the ice– snow interface (0.1 %), while non-MOB methylotrophs were present in abundances similar to natural seawater communities. The dissimilarities in MOB taxa, methane concentrations, and stable isotope ratios between the sea ice and water column point toward different methane dynamics in the two environments

Nanoscale patterning of self-assembled monolayer (SAM)-functionalised substrates with single molecule contact printing

Defined arrangements of individual molecules are covalenty connected ("printed") onto SAM-functionalised gold substrates with nanometer resolution. Substrates were initially pre-functionlised by coating with 3,3′-dithiodipropionic acid (DTPA) to form a self-assembled monolayer (SAM), which was characterised by atomic force microscopy (AFM), contact angle goniometry, cyclic voltammetry and surface plasmon resonance (SPR) spectroscopy. Pre-defined "ink" patterns displayed on DNA origami-based single-use carriers ("stamp") were covalently conjugated to the SAM using 1-ethyl-3-(3-dimethylamino-propyl)carbodiimide (EDC) and N-hydroxy-succinimide (NHS). These anchor points were used to create nanometer-precise single-molecule arrays, here with complementary DNA and streptavidin. Sequential steps of the printing process were evaluated by AFM and SPR spectroscopy. It was shown that 30% of the detected arrangements closely match the expected length distribution of designed patterns, whereas another 40% exhibit error within the range of only 1 streptavidin molecule. SPR results indicate that imposing a defined separation between molecular anchor points within the pattern through this printing process enhances the efficiency for association of specific binding partners for systems with high sterical hindrance. This study expands upon earlier findings where geometrical information was conserved by the application of DNA nanostructures, by establishing a generalisable strategy which is universally applicable to nearly any type of prefunctionalised substrate such as metals, plastics, silicates, ITO or 2D materials

On multiplicity correlations in the STAR data

The STAR data on the multiplicity correlations between narrow psudorapidity bins in the pp and AuAu collisions are discussed. The PYTHIA 8.145 generator is used for the pp data, and a naive superposition model is presented for the AuAu data. It is shown that the PYTHIA generator with default parameter values describes the pp data reasonably well, whereas the superposition model fails to reproduce the centrality dependence seen in the data. Some possible reasons for this failure and a comparison with other models are presented.Comment: 8 pages, 3 figure