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Search Results: 1 - 10 of 6721 matches for " Sarah Kaufmann "
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Are most of the VHE gamma-ray unidentified sources relic PWNe?
Omar Tibolla,Michael Vorster,Sarah Kaufmann,Stefan Ferreira,Karl Mannheim
Physics , 2013,
Abstract: The evolution of Pulsar Wind Nebulae (PWNe) plays a crucial role in interpreting the very high energy (VHE; > 10^11 eV) gamma-ray unidentified sources; and moreover it represents the only viable option to explain the discovery of several "dark sources" in the TeV gamma-ray (i.e. VHE gamma-ray sources without lower energies, radio or X-ray counterparts). The newest time-dependent modeling of PWNe presented in [1] and [2] has to be tested on a broader sample of young well-known PWNe and applied to the full-sample of "dark sources". The consequences of this interpretation go far beyond the interpretation of "dark sources": e.g. there could be strong implication in the origin of cosmic rays and (when considering a leptonic origin of the gamma-ray signal) they can be important for reinterpreting the detection of starburst galaxies in the TeV gamma-ray band.
Data Aggregation: A Proposed Psychometric IPD Meta-Analysis  [PDF]
Esther Kaufmann
Open Journal of Statistics (OJS) , 2018, DOI: 10.4236/ojs.2018.81004
Abstract: Individual participant data (IPD) meta-analysis was developed to overcome several meta-analytical pitfalls of classical meta-analysis. One advantage of classical psychometric meta-analysis over IPD meta-analysis is the corrections of the aggregated unit of studies, namely study differences, i.e., artifacts, such as measurement error. Without these corrections on a study level, meta-analysts may assume moderator variables instead of artifacts between studies. The psychometric correction of the aggregation unit of individuals in IPD meta-analysis has been neglected by IPD meta-analysts thus far. In this paper, we present the adaptation of a psychometric approach for IPD meta-analysis to account for the differences in the aggregation unit of individuals to overcome differences between individuals. We introduce the reader to this approach using the aggregation of lens model studies on individual data as an example, and lay out different application possibilities for the future (e.g., big data analysis). Our suggested psychometric IPD meta-analysis supplements the meta-analysis approaches within the field and is a suitable alternative for future analysis.
No X-Ray Excess from the HESS J1741-302 Region except a New Intermediate Polar Candidate
Hideki Uchiyama,Katsuji Koyama,Hironori Matsumoto,Omar Tibolla,Sarah Kaufmann,Stefan Wagner
Physics , 2011, DOI: 10.1093/pasj/63.sp3.S865
Abstract: With the Suzaku satellite, we observed an unidentified TeV gamma-ray source HESS J1741$-$302 and its surroundings. No diffuse or point-like X-ray sources are detected from the bright southern emission peak of HESS J1741$-$302. From its neighborhood, we found a new intermediate polar candidate at the position of $(\alpha, \delta)_{\rm J2000.0} = (\timeform{17h40m35.6s}, \timeform{-30D14m16s})$, which is designated as Suzaku J174035.6$-$301416. The spectrum of Suzaku J174035.6$-$301416 exhibits emission lines at the energy of 6.4, 6.7 and 7.0 keV, which can be assigned as the K$\alpha$ lines from neutral, He-like and H-like iron, respectively. A coherent pulsation is found at a period of 432.1 $\pm$ 0.1 s. The pulse profile is quasi-sinusoidal in the hard X-ray band (4$-$8 keV), but is more complicated in the soft X-ray band (1$-$3 keV). The moderate period of pulsation, the energy flux, and the presence of the iron K$\alpha$ lines indicate that Suzaku J174035.6$-$301416 is likely an intermediate polar, a subclass of magnetized white dwarf binaries (cataclysmic variables). Based on these discoveries, we give some implications on the origin of GCDX and brief comments on HESS J1741$-$302 and PSR B1737$-$30.
Replication and Virus-Induced Transcriptome of HAdV-5 in Normal Host Cells versus Cancer Cells - Differences of Relevance for Adenoviral Oncolysis
Dominik E. Dorer, Frank Holtrup, Kurt Fellenberg, Johanna K. Kaufmann, Sarah Engelhardt, J?rg D. Hoheisel, Dirk M. Nettelbeck
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0027934
Abstract: Adenoviruses (Ads), especially HAdV-5, have been genetically equipped with tumor-restricted replication potential to enable applications in oncolytic cancer therapy. Such oncolytic adenoviruses have been well tolerated in cancer patients, but their anti-tumor efficacy needs to be enhanced. In this regard, it should be considered that cancer cells, dependent on their tissue of origin, can differ substantially from the normal host cells to which Ads are adapted by complex virus-host interactions. Consequently, viral replication efficiency, a key determinant of oncolytic activity, might be suboptimal in cancer cells. Therefore, we have analyzed both the replication kinetics of HAdV-5 and the virus-induced transcriptome in human bronchial epithelial cells (HBEC) in comparison to cancer cells. This is the first report on genome-wide expression profiling of Ads in their native host cells. We found that E1A expression and onset of viral genome replication are most rapid in HBEC and considerably delayed in melanoma cells. In squamous cell lung carcinoma cells, we observed intermediate HAdV-5 replication kinetics. Infectious particle production, viral spread and lytic activity of HAdV-5 were attenuated in melanoma cells versus HBEC. Expression profiling at the onset of viral genome replication revealed that HAdV-5 induced the strongest changes in the cellular transcriptome in HBEC, followed by lung cancer and melanoma cells. We identified prominent regulation of genes involved in cell cycle and DNA metabolism, replication and packaging in HBEC, which is in accord with the necessity to induce S phase for viral replication. Strikingly, in melanoma cells HAdV-5 triggered opposing regulation of said genes and, in contrast to lung cancer cells, no weak S phase induction was detected when using the E2F promoter as reporter. Our results provide a rationale for improving oncolytic adenoviruses either by adaptation of viral infection to target tumor cells or by modulating tumor cell functions to better support viral replication.
Analysis of Urban Change in Shenzhen City Based on Landsat Archived Data  [PDF]
Tingting Chen, Hermann Josef Kaufmann
Journal of Computer and Communications (JCC) , 2018, DOI: 10.4236/jcc.2018.611014
With the ongoing development of economy and urbanization in China, the change of land use types has attracted more and more attention. In this study we focused on the urban development of Shenzhen City, Guangdong Province, analyzing Landsat 5 TM and Landsat 8 OLI data. We used an SVM based classification, a land transfer matrix approach, a directional growth analysis method and we calculated the inversion of land surface temperature to derive information of land cover changes that occurred in the time period between 1987 and 2017. The results are combined with Shenzhen’s economy, transportation policy and other aspects to find the driving forces of the urban development. The results show that during the observed 30 years, the area of construction land has increased significantly. Most of it is converted from other lands, and some of them are reclaimed. Most rapidly developing are areas west and northwest of the Bao’an, Nanshan and Longhua. The vegetated areas decreased slightly. Caused by the continuous increase of the construction land, the so-called heat island effect emerges slightly but continuously.
On the Free Energy That Drove Primordial Anabolism
Michael Kaufmann
International Journal of Molecular Sciences , 2009, DOI: 10.3390/ijms10041853
Abstract: A key problem in understanding the origin of life is to explain the mechanism(s) that led to the spontaneous assembly of molecular building blocks that ultimately resulted in the appearance of macromolecular structures as they are known in modern biochemistry today. An indispensable thermodynamic prerequisite for such a primordial anabolism is the mechanistic coupling to processes that supplied the free energy required. Here I review different sources of free energy and discuss the potential of each form having been involved in the very first anabolic reactions that were fundamental to increase molecular complexity and thus were essential for life.
Von der empirischen zur "zielgerichteten" Therapie
Kaufmann M
Speculum - Zeitschrift für Gyn?kologie und Geburtshilfe , 2009,
Karst landscape evolution
Speleogenesis and Evolution of Karst Aquifers , 2003,
Abstract: We present results of a numerical study of karst denudation on limestone plateaux. The landscape evolution model used incorporates not only long-range fluvial processes and short-range hill-slope processes, but also large-scale chemical dissolution of limestone surfaces. The relative efficiencies of fluvial and chemical processes are of equal importance to the landscape evolution of a plateau dropping to sea level along an escarpment. While fluvial processes have an impact confined to river channels, the karst denudation process is more uniform, removing material also from the plateau surface. The combined effect of both processes results in a landscape evolution almost twice as effective as the purely erosional evolution of an insoluble landscape.
Virtual Environments for Mathematics and Geometry Education
Hannes Kaufmann
Themes in Science and Technology Education , 2009,
Abstract: Since ancient times mathematicians and geometricians have used visualisations to describe, discuss, study and teach mathematics. In mathematics education, visualisations are still usedwhenever possible to support teaching, to inspire students and feed their need to actually see abstract mathematical facts. In our times, virtual reality presents a fascinating, extremely motivatingnew tool in teachers’ hands which allows students to see mathematics in three dimensions. This article gives an overview of various, mainly immersive, virtual environments that have been developed in the previous 10 years to support mathematics and geometry education. The focus lies on one advanced application for geometry education that has been usedand evaluated with over 500 students throughout the years. Findings and teaching experiences are described and discussed.
A Problemática da Consciência e a Lacuna Explicativa
Nicolas Kaufmann
Princípios : Revista de Filosofia , 1999,
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