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91.
Nontrivial regular polytopes only exist in three and four dimensions. This paper describes a software package that allows to interactively visualize and analyze these regular polytopes. The following four tools are available: Display of the Schlegel diagrams, perspective projections with the possibility of interactively rotating the polytope in three-/four-dimensional space before projection, interactive slicing along various directions, cut-throughs and fold-downs. Various examples illustrate the approach. 相似文献
92.
This study is concerned with the anthropomorphization of technical devices and the resulting influence on human-machine interaction; a special focus is on the verbal interaction between human and machine. Questions included: why do people regard technical devices as humans, when do they do so and how do they perceive their own dialogue and other persons' dialogues with technical devices? Correlation coefficients were calculated between the amount of displayed anthropomorphism and subjects' personality structure, fear of technical devices and self-rated technical competency. A subsequent regression analysis revealed that extraversion and gender of the respondents significantly predicted the amount of interaction with technical devices. Regression analysis showed that neuroticism and agreeableness significantly predicted self-rated technical competency. Technical devices that were seen as helpers or friends were generally treated less unfriendly than devices perceived as merely tools. The findings are discussed in the context of emotion and stress at work and the usability of technical devices. 相似文献
93.
Comparison of detrended fluctuation analysis and spectral analysis for heart rate variability in sleep and sleep apnea 总被引:1,自引:0,他引:1
Penzel T Kantelhardt JW Grote L Peter JH Bunde A 《IEEE transactions on bio-medical engineering》2003,50(10):1143-1151
Sleep has been regarded as a testing situation for the autonomic nervous system, because its activity is modulated by sleep stages. Sleep-related breathing disorders also influence the autonomic nervous system and can cause heart rate changes known as cyclical variation. We investigated the effect of sleep stages and sleep apnea on autonomic activity by analyzing heart rate variability (HRV). Since spectral analysis is suited for the identification of cyclical variations and detrended fluctuation analysis can analyze the scaling behavior and detect long-range correlations, we compared the results of both complementary techniques in 14 healthy subjects, 33 patients with moderate, and 31 patients with severe sleep apnea. The spectral parameters VLF, LF, HF, and LF/HF confirmed increasing parasympathetic activity from wakefulness and REM over light sleep to deep sleep, which is reduced in patients with sleep apnea. Discriminance analysis was used on a person and sleep stage basis to determine the best method for the separation of sleep stages and sleep apnea severity. Using spectral parameters 69.7% of the apnea severity assignments and 54.6% of the sleep stage assignments were correct, while using scaling analysis these numbers increased to 74.4% and 85.0%, respectively. We conclude that changes in HRV are better quantified by scaling analysis than by spectral analysis. 相似文献
94.
Competencies have been formulated for entry level nurses. Specialist and generic advanced nursing competencies are also being developed. This paper describes exploratory groundwork on aged and extended care nursing competencies derived from interviews with nurses, allied health staff, residents and their families from one setting. Critical Incident Technique1 was used to guide semistructured interviews with 29 participants. A thematic analysis of the data suggests that the Australian Nursing Council Inc.2 competencies make a useful but incomplete contribution to understanding the perceived role of nursing in aged and extended care. A conceptual framework developed from the data illustrates the interdependence of competencies with the context in which they are observed. The framework proposes a number of elements which have the potential to offer a means to better interpret nursing competence (critical aspects) in aged and extended care contexts. 相似文献
95.
G. Hausmann 《Fibre Chemistry》1976,7(2):234-234
Chronicle
Birthday greetings to Aleksander Bernardovich Pakshver 相似文献96.
97.
Using FRP reinforcement in construction of the metroline station Brandenburger Tor. At present the metroline station Brandenburger Tor in Berlin is under construction. The station is to be one of the three stations for the provisional shuttle service between Lehrter Bahnhof, Reichstag and Brandenburger Tor. The shuttle service will be in service in the year 2007. As a first step of construction an excavation pit using diaphragm walls is erected where the platform area will be built using conventional mining excavation with ground freezing. In order to establish the ground freezing 30 microtunnels with a diameter of 1.60m have to be driven which will be supplied with frozen lines. For the first time in Germany glass fiber reinforced polymers (FRP) are employed for the extremely stressed diaphragm walls which form the micro tunnels. Because of the low transverse strength the FRP can separated easily. 相似文献
98.
Ludger Blum Robert Deja Roland Peters Detlef Stolten 《International Journal of Hydrogen Energy》2011,36(17):11056-11067
Fuel cell systems are always said to show high electrical efficiency. The results achieved up to now, however, differ considerably, especially between the various fuel cell types all using natural gas as fuel. With the presented study the reasons for the different results and general potentials for fuel cell systems are highlighted. For that purpose several system lay-out concepts were elaborated for PEFC, PAFC and SOFC.The performed energy balance calculations for eight different plant concepts (three PEFC, two PAFC and three SOFC) for steady state operation with methane revealed that because of external reforming PEFC and PAFC systems are limited to about 67% and 70%, respectively, for the fuel utilisation. High temperature fuel cells can achieve at least 80% because of the possibility of internal reforming, or even over 90% in case of anode off-gas recycling. In combination with a cell voltage which is about 100 mV lower than that of MCFC and planar SOFC, PEFC can only achieve 38% of electrical net efficiency, PAFC 42% and tubular SOFC 54%. The latter is similar to MCFC, which is operated at higher cell voltage but lower fuel utilisation. The highest efficiency with up to 63% can be achieved with planar SOFC systems, because this concept allows high fuel utilisation together with high cell voltages. 相似文献
99.
Samuel Owusu Yeboah Yulita Chebotip Mitei Jane Catherine Ngila Ludger Wessjohann Juergen Schmidt 《Journal of the American Oil Chemists' Society》2011,88(10):1539-1549
The lipid components of three Cameroonian seed oils, ke tchock (Aframomum arundinaceum), njangsa (Ricinodendron heudelotii) and calabash nutmeg (Monodora myristica), have been investigated. Gas chromatography (GC)–mass spectrometry (MS) fatty acid (FA) analysis showed M. myristica seed oil to be dominated by linoleic (49.29%) and oleic (37.17%) acids; R. heudelotii was mainly linoleic (58.73%), followed by stearic (15.00%) and oleic (14.21%) acids; A. arundinaceum was predominantly oleic (65.76%) and palmitic (20.36%) acids. Electrospray ionization (ESI)-Fourier transform ion cyclotron
resonance (FTICR)-MS analysis showed seven major triacylglycerol (TAG) classes for M. myristica, with C54:5, C54:4 and C54:6 dominating. R. heudelotii had eight major TAG classes with C54:8, C54:7 and C54:6 being most abundant. A. arundinaceum also had eight major TAG classes with C52:2, C54:3 and C50:2 dominating. 13C nuclear magnetic resonance (NMR) analysis of the TAGs showed that both sn-1,3 and sn-2 positions were predominantly occupied by linoleoyl and oleoyl chains. High-performance liquid chromatography (HPLC) fluorescence
detector (FLD) analysis showed that M. myristica contained only α- and β-tocopherols (195.40 and 73.95 μg/g, respectively), R. heudelotii contained mainly γ-tocopherol (289.40 μg/g), and A. arundinaceum had mainly γ- and β-tocopherols (236.78 and 124.93 μg/g, respectively). GC–MS analysis of the unsaponifiable matter showed
that β-sitosterol was the most abundant phytosterol in all three seed oils. The absolute amounts of 4-desmethylsterols were
196.15, 608.71 and 362.15 μg/g for M. myristica, R. heudelotii and A. arundinaceum seed oils, respectively. These compositional and structural studies provide justification for the use of all three seed oils
in food products. 相似文献
100.
RL Ufret-Vincenty L Quigley N Tresser SH Pak A Gado S Hausmann KW Wucherpfennig S Brocke 《Canadian Metallurgical Quarterly》1998,188(9):1725-1738
A peptide derived from the human papillomavirus L2 protein is recognized by a myelin basic protein (MBP)-specific T cell clone from a multiple sclerosis patient and by MBP-specific autoantibodies purified from multiple sclerosis brain tissue. We now show in mice that low doses of this papillomavirus peptide were optimal in selecting a subpopulation of papillomavirus peptide-specific T cells that cross-reacted with MBP(87-99) and with an unrelated viral peptide derived from the BSLF1 protein of Epstein-Barr virus (EBV). These low dose viral peptide- specific T cell lines were highly encephalitogenic. Splenocytes from mice transferred with viral peptide-specific T cells showed a vigorous response to both the papillomavirus and MBP peptides, indicating that viral antigen-specific T cells survived for a prolonged time in vivo. The EBV peptide, unable to prime and select an autoreactive T cell population, could still activate the low dose papillomavirus peptide-specific cells and induce central nervous system (CNS) autoimmunity. Cytokine profiles of papillomavirus peptide-specific encephalitogenic T cells and histopathology of CNS lesions resembled those induced by MBP. These results demonstrate conserved aspects in the recognition of the self-antigen and a cross-reactive viral peptide by human and murine MBP-specific T cell receptors. We demonstrate that a viral antigen, depending on its nature, dose, and number of exposures, may select autoantigen-specific T cells that survive in vivo and can trigger autoimmune disease after adoptive transfer. 相似文献