Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99


Any time

2020 ( 9 )

2019 ( 42 )

2018 ( 44 )

2017 ( 42 )

Custom range...

Search Results: 1 - 10 of 15026 matches for " Christian Kluge "
All listed articles are free for downloading (OA Articles)
Page 1 /15026
Display every page Item
Efficiency Evaluation of Extraction Methods for Analysis of OCPs and PCBs in Soils of Varying TOC  [PDF]
Ulrike Mülow-Stollin, Petra Lehnik-Habrink, Stephanie Kluge, Wolfram Bremser, Christian Piechotta
Journal of Environmental Protection (JEP) , 2017, DOI: 10.4236/jep.2017.86045
Abstract: Organochlorine pesticides and polychlorinated biphenyls are toxic, carcinogenic, and have a high potential for bioaccumulation. Due to their stability, they are still considered an environmental problem even though the use of most of them has been phased out several decades ago. Soil is a matrix which can retain these contaminants to a great extent. This ability is often associated with the total organic carbon content (TOC). In order to judge the pollution status of soil and to make monitoring data more easily comparable a simple, yet robust extraction method is needed. Agitation solid-liquid-extraction is well suited for this purpose. However, the influence of TOC on the analyte recovery has to be known. For the presented study, 12 organochlorine pesticides and 7 polychlorinated biphenyls were spiked into four model soils with organic carbon contents between 1.6% - 13.3%. The matrices were extracted using solid-liquid extraction between 45 minutes and 16 hours. For comparison, all soils were also extracted using pressurised liquid extraction and Soxhlet extraction. After clean-up the extracts were measured using a gas chromatography-mass spectrometry (GC-MS) system. Statistical analysis of the results implied that the TOC content of the soils did not have significant influence on the extraction efficiency. A longer solid-liquid extraction time did not necessarily increase analyte recovery: Extraction for one hour resulted in 88% recovery while 16 hour extraction led to 89%. Thus, the efficiency of all the methods was comparable for all model soils. Additional investigations regarding GC liner performance highlighted the need for isotopically labelled standards during the analysis of thermolabile pesticides.
Patterns of Coupled Theta Activity in Amygdala-Hippocampal-Prefrontal Cortical Circuits during Fear Extinction
J?rg Lesting, Rajeevan T. Narayanan, Christian Kluge, Susan Sangha, Thomas Seidenbecher, Hans-Christian Pape
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0021714
Abstract: Signals related to fear memory and extinction are processed within brain pathways involving the lateral amygdala (LA) for formation of aversive stimulus associations, the CA1 area of the hippocampus for context-dependent modulation of these associations, and the infralimbic region of the medial prefrontal cortex (mPFC) for extinction processes. While many studies have addressed the contribution of each of these modules individually, little is known about their interactions and how they function as an integrated system. Here we show, by combining multiple site local field potential (LFP) and unit recordings in freely behaving mice in a fear conditioning paradigm, that theta oscillations may provide a means for temporally and functionally connecting these modules. Theta oscillations occurred with high specificity in the CA1-LA-mPFC network. Theta coupling increased between all areas during retrieval of conditioned fear, and declined during extinction learning. During extinction recall, theta coupling partly rebounded in LA-mPFC and CA1-mPFC, and remained at a low level in CA1-LA. Interfering with theta coupling through local electrical microstimulation in CA1-LA affected conditioned fear and extinction recall depending on theta phase. These results support the hypothesis that theta coupling provides a means for inter-areal coordination in conditioned behavioral responsiveness. More specifically, theta oscillations seem to contribute to a population code indicating conditioned stimuli during recall of fear memory before and after extinction.
Using XFELs for Probing of Complex Interaction Dynamics of Ultra-Intense Lasers with Solid Matter
Thomas Kluge,Christian Gutt,Lingen Huang,Josefine Metzkes,Ulrich Schramm,Michael Bussmann,Thomas E. Cowan
Physics , 2013, DOI: 10.1063/1.4869331
Abstract: We demonstrate the potential of X-ray free-electron lasers (XFEL) to advancethe understanding of complex plasma dynamics by allowing for the first time nanometer and femtosecond resolution at the same time in plasma diagnostics. Plasma phenomena on such short timescales are of high relevance for many fields of physics, in particular in the ultra-intense ultra-short laser interaction with matter. Highly relevant yet only partially understood phenomena may become directly accessible in experiment. These include relativistic laser absorption at solid targets, creation of energetic electrons and electron transport in warm dense matter, including the seeding and development of surface and beam instabilities, ambipolar expansion, shock formation, and dynamics at the surfaces or at buried layers. We demonstrate the potentials of XFEL plasma probing for high power laser matter interactions using exemplary the small angle X-ray scattering technique, focusing on general considerations for XFEL probing.
Empirisch begründete Typenbildung in der qualitativen Sozialforschung Empirically Grounded Construction of Types and Typologies in Qualitative Social Research La construcción empírica de tipos en la investigación cualitativa
Susann Kluge
Forum : Qualitative Social Research , 2000,
Abstract: In der qualitativen Sozialforschung finden sich nur wenige Ans tze, in denen der Proze der Typenbildung detailliert expliziert und systematisiert wird; au erdem werden sehr unterschiedliche Typenbegriffe (wie z.B. Idealtypen, Realtypen, Prototypen, Extremtypen, Strukturtypen etc.) verwendet. Da der Typusbegriff für die qualitative Sozialforschung von zentraler Bedeutung ist, ist eine Kl rung des Begriffs sowie des Prozesses der Typenbildung jedoch dringend erforderlich. In dem Beitrag wird daher zun chst eine allgemeine Definition des Typusbegriffs vorgelegt, von der ausgehend Regeln für eine systematische und nachvollziehbare Bildung von Typen und Typologien formuliert werden. URN: urn:nbn:de:0114-fqs0001145 In qualitative social research, there are only a few approaches in which the process of typology construction is explicated and systematised in detail; furthermore, you can find very different concepts of types like ideal types, real types, prototypes, extreme types, types of structure. Because the construction of typologies is of central importance for the qualitative social research, it is necessary to clarify the concept of types and the process of typology construction. Therefore, this article will first present a general definition of the concept of types, and then how this definition forms the basis of rules for a systematic and controlled construction of types and typologies. URN: urn:nbn:de:0114-fqs0001145 URN: urn:nbn:de:0114-fqs0001145
Kluge, Angela
Afrikanistik Online , 2008,
A synchronic lexical study of the Ede language continuum of West Africa: The effects of different similarity judgment criteria
Kluge, Angela
Afrikanistik Online , 2007,
Abstract: In the context of a synchronic lexical study of the Ede varieties of West Africa, this paper investigates whether the use of different criteria sets to judge the similarity of lexical features in different language varieties yields matching conclusions regarding the relative relationships and clustering of the investigated varieties and thus leads to similar recommendations for further sociolinguistic research. Word lists elicited in 28 Ede varieties were analyzed with the inspection method. To explore the effects of different similarity judgment criteria, two different similarity judgment criteria sets were applied to the elicited data to identify similar lexical items. The quantification of these similarity decisions led to the computation of two similarity matrices which were subsequently analyzed by means of correlation analysis and multidimensional scaling. The findings of this analysis suggest compatible conclusions regarding the relative relationships and clustering of the investigated Ede varieties. However, the matching clustering results do not necessarily lead to the same recommendations for more in-depth sociolinguistic research, when interpreted in terms of an absolute lexical similarity threshold. The indicated ambiguities suggest the usefulness of focusing on the relative, rather than absolute in establishing recommendations for further sociolinguistic research.
Initial State Radiation: A success story
W. Kluge
Physics , 2008, DOI: 10.1016/j.nuclphysbps.2008.09.051
Abstract: The investigation of events with Initial State Radiation (ISR) and subsequent Radiative Return has become an impressively successful and guiding tool in low and intermediate energy hadron physics with electron positron colliders: it allows to measure hadronic cross sections and the ratio R from threshold up to the maximum energy of the colliders running at fixed energy, to clarify reaction mechanisms and reveal substructures (intermediate states and their decay mechanisms) and to search for new highly excited mesonic states with J^{PC} = 1^{--}. While being discussed since the sixties-seventies ISR became a powerful tool for experimentalists only with the development of EVA-PHOKHARA, a Monte Carlo generator developed over almost 10 years, while increasing its complexity, which is user friendly, flexible and easy to implement into the software of existing detectors.
Summary of H1 Results on the Strong Coupling from Inclusive and Final States
Thomas Kluge
Physics , 2007,
Abstract: Several determinations of the strong coupling from the H1 Collaboration are reviewed.
Multi Jet Production at High Q2
Thomas Kluge
Physics , 2005, DOI: 10.1063/1.2122134
Abstract: Deep-inelastic $e^+p$ scattering data, taken with the H1 detector at HERA, are used to investigate jet production over a range of four-momentum transfers $150 < Q^2 < 15000 \mathrm{GeV}^2$ and transverse jet energies $5 < E_T < 50 \mathrm{GeV}$. The analysis is based on data corresponding to an integrated luminosity of $\mathcal{L}_\mathrm{int} = 65.4 \mathrm{pb}^{-1}$ taken in the years 1999-2000 at a centre-of-mass energy $\sqrt{s} \approx 319 \mathrm{GeV}$. Jets are defined by the inclusive $k_t$ algorithm in the Breit frame of reference. Dijet and trijet jet cross sections are measured with respect to the exchanged boson virtuality and in addition the ratio of the trijet to the dijet cross section $R_{3/2}$ is investigated. The results are compared to the predictions of perturbative QCD calculations in next-to-leading order in the strong coupling constant $\alpha_s$. The value of $\alpha_s(m_Z)$ determined from the study of $R_{3/2}$ is $\alpha_s(m_Z) = 0.1175 \pm 0.0017 (\mathrm{stat.}) \pm 0.0050 (\mathrm{syst.}) ^{+0.0054}_{-0.0068} (\mathrm{theo.})$.
Studies of heavy flavour production and the hadronic final state in high energy ep collisions
Thomas Kluge
Physics , 2005, DOI: 10.1063/1.2176511
Abstract: An extract of recent results from the H1 and ZEUS Collaborations is shown. Various properties of quantum chromo dynamics are investigated by studying the details of the hadronic final state of high energy electron proton collisions at HERA. The presented results include analyses of jet cross sections and single particle production such as $\gamma$ and $D$. Part of the measurements deal with final states involving identified heavy quarks (charm and beauty).
Page 1 /15026
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.