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Institution

Bielefeld University

EducationBielefeld, 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.


Papers
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Journal ArticleDOI
TL;DR: It was found that hydrocortisone decreased brain activity in both the hippocampus and PFC during successful retrieval of neutral words, consistent with previous animal and human studies suggesting that glucocorticoids modulate both hippocampal and prefrontal brain regions that are crucially involved in memory processing.
Abstract: Glucocorticoids (GCs, cortisol in human) are associated with impairments in declarative memory retrieval. Brain regions hypothesized to mediate these effects are the hippocampus and prefrontal cortex (PFC). Our aim was to use fMRI in localizing the effects of GCs during declarative memory retrieval. Therefore, we tested memory retrieval in 21 young healthy males in a randomized placebo-controlled crossover design. Participants encoded word lists containing neutral and emotional words 1 h prior to ingestion of 20 mg hydrocortisone. Memory retrieval was tested using an old/new recognition paradigm in a rapid event-related design. It was found that hydrocortisone decreased brain activity in both the hippocampus and PFC during successful retrieval of neutral words. These observations are consistent with previous animal and human studies suggesting that glucocorticoids modulate both hippocampal and prefrontal brain regions that are crucially involved in memory processing.

132 citations

Journal ArticleDOI
TL;DR: In this paper, Krohn and Weyer discuss the role of real-life experiments in the implementation of verified knowledge in the context of research processes and their related risks beyond the limits of the laboratory or other such institution and directly into the wider society.
Abstract: Professor Wolfgang Krohn and Priv-Doz Dr Johannes Weyer are in the Fakultat fur Soziologie, Universitat Bielefeld, Universitatsstrasse 25, D-33615 Bielefeld, Germany. This paper was written in connection with several research projects in which 'experimental implementations' of various kinds were studied (see Herbold, Krohn and Weyer, 1991; Herbold, Krohn and Weyer, 1992; Asdonk, Bredeweg and Kowol, 1991; and Weyer, 1994). IN M O D E R N SCIENCE, there is an increasing tendency to extend research processes and their related risks beyond the limits of the laboratory or other such institution, and directly into the wider society. To greater or lesser extents, these moves are experiments. This tendency is apparent in, for instance, nuclear energy technologies, some developments in ecology, the use of physiologically dangerous chemicals, the introduction of some medicines, and in some military technology. A common denominator in such cases is that they cannot be legitimised in the name of research alone. In keeping with at least the German way of viewing them, they are declared to be the 'implementation of verified knowledge', and are justified on the basis of non-scientific (for instance commercial) interests. With the increased rate of technological innovation in recent decades, the implementation of verified knowledge has frequently become (nolens volens) the testing of risk-involving technologies. For want of a better term, we will refer to these processes as 'experimental implementation(s)', 'real-life experiments' or 'implicit experiments'. The 'risks' of interest here are related to safety, not to (for instance) the probability of obtaining publishable scientific results or of making profits. These terms have been chosen to suggest that the introduction of new technologies frequently reveals features of the traditional laboratory experimental generation of knowledge. Indeed, this is often deliberately built into the design of the project. Real-life experiments, however, differ fundamentally in one aspect from traditional ex-

132 citations

Journal ArticleDOI
TL;DR: A method based on three neural networks of the local linear map type which enables a computer to identify the head orientation of a user by learning from examples is presented.
Abstract: Humans easily recognize where another person is looking and often use this information for interspeaker coordination. We present a method based on three neural networks of the local linear map type which enables a computer to identify the head orientation of a user by learning from examples. One network is used for color segmentation, a second for localization of the face, and the third for the final recognition of the head orientation. The system works at a frame rate of one image per second on a common workstation, We analyze the accuracy achieved at different processing steps and discuss the usability of the approach in the context of a visual human-machine interface.

132 citations

Journal ArticleDOI
TL;DR: Cross sections for both processes for incident-positron energies ranging from the respective thresholds to 1000 eV are determined and the positronium-formation cross section lies above all theoretical predictions.
Abstract: Positrons ionize helium atoms either by impact ionization, resulting in three outgoing particles, or by positronium formation. We determined cross sections for both processes for incident-positron energies ranging from the respective thresholds to 1000 eV. The cross section for impact ionization by positrons (${\ensuremath{\sigma}}_{\mathrm{ion}}^{+}$) exceeds the corresponding electron cross section (${\ensuremath{\sigma}}_{\mathrm{ion}}^{\ensuremath{-}}$) below 500 eV. On the high-energy side of its maximum, the positronium-formation cross section (${\ensuremath{\sigma}}_{\mathrm{Ps}}$) lies above all theoretical predictions.

132 citations

Journal ArticleDOI
TL;DR: In this article, the off-shell correction to the massive quark propagator in an arbitrary covariant gauge is calculated and results for the bare and renormalized propagator are presented.

132 citations


Authors

Showing all 10375 results

NameH-indexPapersCitations
Stefan Grimme113680105087
Alfred Pühler10265845871
James Barber10264242397
Swagata Mukherjee101104846234
Hans-Joachim Werner9831748508
Krzysztof Redlich9860932693
Graham C. Walker9338136875
Christian Meyer93108138149
Muhammad Farooq92134137533
Jean Willy Andre Cleymans9054227685
Bernhard T. Baune9060850706
Martin Wikelski8942025821
Niklas Luhmann8542142743
Achim Müller8592635874
Oliver T. Wolf8333724211
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
2023150
2022511
20211,696
20201,655
20191,410
20181,299