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91.
J. Wolfrum 《Applied physics. B, Lasers and optics》1988,46(3):221-236
In recent years, various methods have been developed to observe and to influence the course of chemical reactions using laser radiation. By selectively increasing the translational, rotational, and vibrational energies and by controlling the relative orientation of the reaction partners with tunable infrared and UV lasers, direct insight can be gained into the molecular course of the breaking and re-forming of chemical bonds. As exmaples for the application of lasers in chemical synthesis the production of monomers and catalysts is discussed. The application of linear and nonlinear laser spectroscopic methods, such as laser-induced fluorescence (LIF), Coherent anti-Stokes Raman Scattering (CARS), infrared-absorption measurements with tunable diode and molecular lasers is described for non-intrusive observation of the interaction of transport processes with chemical reactions used in industrial processes with high temporal, spectral and spatial resolution. Finally the application of a UV laser microbeam apparatus in genetic engineering for laser-induced cell fusion, genetic transformation of plant cells as well as diagnosis of human diseases by laser-microdissection of chromosomes is described. 相似文献
92.
A. Roggan D. Schädel U. Netz J.-P. Ritz C.-T. Germer G. Müller 《Applied physics. B, Lasers and optics》1999,69(5-6):445-453
The absorption coefficient μa, the scattering coefficient μs, and the scattering anisotropy factor g of porcine liver were studied in vitro using the integrating sphere technique and
inverse Monte Carlo simulation in the wavelength range 450 to 700 nm. A reference preparation technique was developed using
a dermatome providing specimens of 200 to 800 μm thickness without pre-freezing the tissue. The optical parameters as measured
applying the reference preparation were compared to those measured after cryo-homogenisation. We found significant deviations
of the scattering coefficient and the anisotropy factor which were compensated when the reduced scattering coefficient μs
′ was calculated. We also compared the effects of freezing reference specimens at -20 °C and at 77 K without homogenisation.
For both freezing protocols noticeable deviations were found in all three optical parameters as well as in μs
′. The impact of tissue storage at 4 °C was measured in the range 4 to 48 h post mortem and showed a clear reduction of μa and a significant increase of μs even after 24 h of storage. Short-time storage of the specimens in saline solution reduced all three optical parameters significantly.
In conclusion, the tissue preparation must be controlled in order to provide in vitro optical parameters that sufficiently
mimic the in vivo situation.
Received: 29 June 1999 / Revised version: 1 October 1999 / Published online: 3 November 1999 相似文献
93.
David Garofalo 《Annalen der Physik》2020,532(4):1900480
Spin measurement of the 6.5 billion solar mass black hole in M87 from the Event Horizon Telescope image is the latest in a series that span a wide range in values, but that tend to share the feature of corotation between the accretion flow and black hole. The spin paradigm for black holes predicts very high black hole spin which in that framework is produced in its last significant merger. High black hole spin appears to be ruled out in the gap paradigm, however, which predicts early formation with a mass already in excess of 4 billion solar masses. In this picture, the black hole experiences slow evolution as it departs from its original radio quasar phase and over billions of years not only fails to double its mass but also falls short of regaining its original high spin, such that it is now compatible with a corotating accreting black hole whose dimensionless spin fits best in the range 0.2 < a < 0.5. 相似文献
94.
《Quaestiones Mathematicae》2013,36(2):241-256
Abstract Given a C*-algebra A and a suitable set of derivations on A, we consider the algebras A n of n-differentiable elements of A as described in [B], before passing to an analysis of important classes of bounded linear maps between two such spaces. We show that even in this general framework, all the main features of the theory for the case C(m)(U) → C (p) (V) where U and V are open balls in suitable Banach spaces, are preserved (see for example [A-G-L], [Gu-L], [Ja] and [L]). As part of the theory developed we obtain a non-trivial extension of the Kleinecke-Shirokov theorem in the category of C*-algebras to unbounded partially defined *-derivations. This indicates the existence of a single mathematical principle governing both the non-increasibility of differentiability by continuous homomorphisms and the untenability of the Heisenberg Uncertainty Principle for bounded observables. 相似文献
95.
Brooke E. Crowley Claudia Wultsch Marcella J. Kelly 《Isotopes in environmental and health studies》2013,49(5):478-498
ABSTRACTFaecal isotopic analysis may complement other non-invasive wildlife survey tools for monitoring landscape use by carnivores, such as motion-detecting cameras and non-invasive genetic sampling. We analysed carbon, nitrogen, and strontium isotopes in faecal matter produced by jaguars (Panthera onca) as well as bones from consumed prey at the Mountain Pine Ridge Forest Reserve (MPR) in Belize, Central America. The MPR is ideally suited for a spatial isotope study as vegetation and geology both vary considerably. The isotopic composition of faecal matter should reflect the habitat and geology where consumed prey lived. We used bone from consumed prey recovered from jaguar scats as a proxy for diet. Faecal matter and bone showed comparable spatial isotopic trends, suggesting that the isotopic composition of jaguar faeces can be used to detect foraging in different habitats (pine forest versus broadleaf forest) or on different geologies (Mesozoic carbonates; Palaeozoic granite, contact metamorphics, and metasediments). This result is reassuring as bones are not always present in carnivore scats. Studying landscape use by cryptic and wide-ranging carnivore species like jaguars remains challenging. Isotopic analysis of faecal matter complements the existing array of non-invasive spatial monitoring tools. 相似文献
96.
M. Zaduban 《Isotopes in environmental and health studies》2013,49(5):160-166
Anhand kernphysikalischer Charakteristika wird die Möglichkeit, einige natürliche instabile Nuklide in der Metrologie zu verwenden, diskutiert. Als Standards sind 40K und 87Rb sehr gut geeignet. Unter Berücksichtigung der Kriterien für Standards wurden die geeignetsten Kalium- und Rubidiumsalze ausgewählt, und an einigen Beispielen wird ihre praktische Anwendung gezeigt. 相似文献
97.
Serge Lazzarini Thierry Masson 《Journal of Geometry and Physics》2012,62(2):387-402
In this paper, we show how connections and their generalizations on transitive Lie algebroids are related to the notion of connections in the framework of the derivation-based noncommutative geometry. In order to compare the two constructions, we emphasize the algebraic approach of connections on Lie algebroids, using a suitable differential calculus. Two examples allow this comparison: on the one hand, the Atiyah Lie algebroid of a principal fiber bundle and, on the other hand, the space of derivations of the algebra of endomorphisms of an SL(n,C)-vector bundle. Gauge transformations are also considered in this comparison. 相似文献
98.
Abstract The intensity ratio of the T′/T87Rb NMR lines in Rb3C60 could be changed by different cooling rates after annealing at 380 °C. The results are discussed with respect to magnetically different surroundings of the Rb ions through the two standard orientations of the C60 3-ions. Additionally, the superconducting volume fraction is influenced by the different cooling procedures. 相似文献
99.
In the framework of locally compact quantum groups, we study cocycle actions. We develop the cocycle bicrossed product construction, starting from a matched pair of locally compact quantum groups. We define exact sequences and establish a one-to-one correspondence between cocycle bicrossed products and cleft extensions. In this way, we obtain new examples of locally compact quantum groups. 相似文献
100.
A class of C∗-algebras called quantum Heisenberg manifolds were introduced by Rieffel in (Comm. Math. Phys. 122 (1989) 531) as strict deformation quantization of Heisenberg manifolds. Using the ergodic action of Heisenberg group we construct a family of spectral triples. It is shown that associated Kasparov modules are homotopic. We also show that they induce cohomologous elements in entire cyclic cohomology. The space of Connes-deRham forms have been explicitly calculated. Then we characterize torsionless/unitary connections and show that there does not exist a connection that is simultaneously torsionless and unitary. Explicit examples of connections are produced with negative scalar curvature. This part illustrates computations involving some of the concepts introduced in Frohlich et al. (Comm. Math. Phys. 203 (1999) 119), for which to the best of our knowledge no infinite-dimensional example is known other that the noncommutative torus. 相似文献