403 research outputs found
Fusion mechanism in fullerene-fullerene collisions -- The deciding role of giant oblate-prolate motion
We provide answers to long-lasting questions in the puzzling behavior of
fullerene-fullerene fusion: Why are the fusion barriers so exceptionally high
and the fusion cross sections so extremely small? An ab initio nonadiabatic
quantum molecular dynamics (NA-QMD) analysis of C+C collisions
reveals that the dominant excitation of an exceptionally "giant" oblate-prolate
H mode plays the key role in answering both questions. From these
microscopic calculations, a macroscopic collision model is derived, which
reproduces the NA-QMD results. Moreover, it predicts analytically fusion
barriers for different fullerene-fullerene combinations in excellent agreement
with experiments
LEKTOR - ein Programm zur Lesetext-Evaluation
Die vorliegende Arbeit stellt das von mir "LEKTOR" genannte, fur das Microsoft Windows Betriebssystem entwickelte Programm vor. Es ermoglicht einer im Bereich "Deutsch als Fremdsprache" (DaF) tatigen Lehrperson, Texte auf ihre Leseschwierigkeit fur Lerner zu uberprufen. Dabei gestattet das Programm folgende Dinge: ・den Schwierigkeitsgrad eines Textes zu bestimmen ・eine Wortliste der Worter auszugeben, die den festgelegten Schwierigkeitsgrad ubersteigen・allgemeine statistische Informationen zum Text zu erhalten wie Wortzahl, Satzzahl, etc. ・eine grobe syntaktische Analyse der Satze auszugeben Um all das zu ermoglichen, wurde ein Grundwortschatz von ca. 1600 Wortern gewichtet/gradiert und in 10 Stufen eingeteilt. Die Worter des Textes werden analysiert, mit den entsprechenden Lexikoneintragungen verglichen und je nach Vorgabe eine Liste erstellt und ausgegeben.Fur die syntaktische Analyse wurde kein formalisiertes Sprachmodell verwendet, weil eine solche Analyse nicht das Hauptanliegen fur die gestellte Aufgabe war. Stattdessen wurden Methoden, wie sie bei PoS-Taggern angewendet werden, sowie eigene heuristische Ansatze eingesetzt
Separate Universe Simulations with IllustrisTNG: baryonic effects on power spectrum responses and higher-order statistics
We measure power spectrum response functions in the presence of baryonic
physical processes using separate universe simulations with the IllustrisTNG
galaxy formation model. The response functions describe how the small-scale
power spectrum reacts to long-wavelength perturbations and they can be
efficiently measured with the separate universe technique by absorbing the
effects of the long modes into a modified cosmology. Specifically, we focus on
the total first-order matter power spectrum response to an isotropic density
fluctuation , which is fully determined by the logarithmic derivative
of the nonlinear matter power spectrum and the
growth-only response function . We find that is not
affected by the baryonic physical processes in the simulations at redshifts and on all scales probed (, i.e. length scales
). In practice, this implies that the power spectrum
fully specifies the baryonic dependence of its response function. Assuming an
idealized lensing survey setup, we evaluate numerically the baryonic impact on
the squeezed-lensing bispectrum and the lensing super-sample power spectrum
covariance, which are given in terms of responses. Our results show that these
higher-order lensing statistics can display varying levels of sensitivity to
baryonic effects compared to the power spectrum, with the squeezed-bispectrum
being the least sensitive. We also show that ignoring baryonic effects on
lensing covariances slightly overestimates the error budget (and is therefore
conservative from the point of view of parameter error bars) and likely has
negligible impact on parameter biases in inference analyses.Comment: 15 pages, 6 figures, 1 table; comments welcomed! v2 matches version
published in MNRA
Sustainability in Information Systems: Assortment of Current Practices in IS Organizations
The increasing dissemination of information systems into all areas of business and personal life has drawn attention to its environmental effects. IS organizations are becoming aware that they have to take up their responsibility by thinking seriously about sustainability management for information systems. While measures for using computing resources efficiently have received considerable attention, the topic of sustainability in IS management is still lacking theoretical foundation. The purpose of this paper is to explore current environmental efforts in sustainable IS management. Based on fifteen expert interviews with CIOs, IS and environmental managers from IS organizations, the paper provides researchers and practitioners alike with an explorative study on the situation of sustainability in IS operations and, thus, makes a contribution to this emerging IS research topic
Influence of Green IT on Consumers’ Buying Behavior of Personal Computers: Implications from a Conjoint Analysis
The increasing attention towards the environmental impact of IT (Information Technology) demands reorientation from IT hardware and service organisations. Consumers are more than ever sensitive about the environmental impact of products and services they buy. Environmental attributes therefore play an important role in the buying process. While the concept of Green IT has been primarily researched from the corporate perspective, the consumer perspective has widely been neglected. The purpose of this paper is to evaluate the influence of Green IT attributes of PCs (Personal Computers) on the buying behaviour of consumers. As a contribution to the ongoing discussion of Green IT, we provide marketing data from 500 participants on the importance of Green IT using conjoint and cluster analysis. It is shown that the market share for Green IT PCs could be up to 26.6%. Especially female customers value environmentally friendly attributes. Thereafter, we draw recommendations for the marketing mix of IT hardware and service organisations. The results should provide researchers and practitioners with new insights and measures about the relevance and application of Green IT in the scope of PCs
End-of-fill study on collimator tight settings
In 2010 and 2011 the collimation system has been operated with relaxed settings, i.e. with retractions between
different collimator families larger than the nominal settings that provide optimum cleaning. This configuration ensured a sufficient cleaning performance at 3.5 TeV while allowing larger tolerances on orbit control.
Tighter collimator settings were proposed to push the cleaning performance and to allow larger orbit margins
between TCDQ dump protection and tertiary collimators. With the same margins as with the relaxed settings, the β∗ could be reduced. After having verified with beam that the cleaning is improved as expected,
the feasibility of tighter collimator settings must be addressed with high stored intensity. For this purpose, an
end-of-fill study was proposed after a standard physics fill with 1380 bunches nominal bunches at 3.5 TeV, for
a total stored energy of 95 MJ. During this test, primary and secondary collimators were moved to tight settings after about 8 hours of stable physics conditions in all experiments. This note summarises the operational
procedure followed and the results of beam measurements during this study.peer-reviewe
Spin-transfer in an open ferromagnetic layer: from negative damping to effective temperature
Spin-transfer is a typical spintronics effect that allows a ferromagnetic
layer to be switched by spin-injection. Most of the experimental results about
spin transfer are described on the basis of the Landau-Lifshitz-Gilbert
equation of the magnetization, in which additional current-dependent damping
factors are added, and can be positive or negative. The origin of the damping
can be investigated further by performing stochastic experiments, like one shot
relaxation experiments under spin-injection in the activation regime of the
magnetization. In this regime, the N\'eel-Brown activation law is observed
which leads to the introduction of a current-dependent effective temperature.
In order to justify the introduction of these counterintuitive parameters
(effective temperature and negative damping), a detailed thermokinetic analysis
of the different sub-systems involved is performed. We propose a thermokinetic
description of the different forms of energy exchanged between the electric and
the ferromagnetic sub-systems at a Normal/Ferromagnetic junction. The
corresponding Fokker Planck equations, including relaxations, are derived. The
damping coefficients are studied in terms of Onsager-Casimir transport
coefficients, with the help of the reciprocity relations. The effective
temperature is deduced in the activation regime.Comment: 65 pages, 10 figure
Quantitative, Multi-institutional Evaluation of MR Thermometry Accuracy for Deep-Pelvic MR-Hyperthermia Systems Operating in Multi-vendor MR-systems Using a New Anthropomorphic Phantom
Clinical outcome of hyperthermia depends on the achieved target temperature, therefore target conformal heating is essential. Currently, invasive temperature probe measurements are the gold standard for temperature monitoring, however, they only provide limited sparse data. In contrast, magnetic resonance thermometry (MRT) provides unique capabilities to non-invasively measure the 3D-temperature. This study investigates MRT accuracy for MR-hyperthermia hybrid systems located at five European institutions while heating a centric or eccentric target in anthropomorphic phantoms with pelvic and spine structures. Scatter plots, root mean square error (RMSE) and Bland–Altman analysis were used to quantify accuracy of MRT compared to high resistance thermistor probe measurements. For all institutions, a linear relation between MRT and thermistor probes measurements was found with R2 (mean ± standard deviation) of 0.97 ± 0.03 and 0.97 ± 0.02, respectively for centric and eccentric heating targets. The RMSE was found to be 0.52 ± 0.31 °C and 0.30 ± 0.20 °C, respectively. The Bland-Altman evaluation showed a mean difference of 0.46 ± 0.20 °C and 0.13 ± 0.08 °C, respectively. This first multi-institutional evaluation of MR-hyperthermia hybrid systems indicates comparable device performance and good agreement between MRT and thermistor probes measurements. This forms the basis to standardize treatments in multi-institution studies of MR-guided hyperthermia and to elucidate thermal dose-effect relations
Absence of chronic hepatitis E in a German cohort of common variable immunodeficiency patients
Cases of chronic or prolonged hepatitis E virus (HEV) infections have been described in solid organ transplant recipients, HIV infected patients and in patients with malignancies or idiopathic CD4+ T lymphopenia. It is unknown if HEV infection also takes chronic courses in patients with common variable immunodeficiency (CVID). We studied a cohort of 73 CVID patients recruited in a low endemic Central European country. None of the subjects tested positive for HEV RNA or anti-HEV IgG. Immunoglobulin transfusions (n=10) tested negative for HEV RNA but all were anti-HEV positive. To verify that such pooled blood products contain anti-HEV protective antibodies we measured the anti-HEV IgG optical density (OD) values in patients before and after transfusion. Anti-HEV OD values increased after infusion but did not reach the cut-off considered as positive. Thus, chronic HEV infections seem to be rare events in CVID patients in Germany. Commercially available immuno globulin infusions contain anti HEV antibodies and may contribute to protection from HEV infectio
- …