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1.
Klaus Reinhardt Hans Georg Breunig Aisada Uchugonova Karsten K?nig 《Journal of the Royal Society Interface》2015,12(110)
We explore the possibility of characterizing sperm cells without the need to stain them using spectral and fluorescence lifetime analyses after multi-photon excitation in an insect model. The autofluorescence emission spectrum of sperm of the common bedbug, Cimex lectularius, was consistent with the presence of flavins and NAD(P)H. The mean fluorescence lifetimes showed smaller variation in sperm extracted from the male (tau m, τm = 1.54–1.84 ns) than in that extracted from the female sperm storage organ (tau m, τm = 1.26–2.00 ns). The fluorescence lifetime histograms revealed four peaks. These peaks (0.18, 0.92, 2.50 and 3.80 ns) suggest the presence of NAD(P)H and flavins and show that sperm metabolism can be characterized using fluorescence lifetime imaging. The difference in fluorescence lifetime variation between the sexes is consistent with the notion that female animals alter the metabolism of sperm cells during storage. It is not consistent, however, with the idea that sperm metabolism represents a sexually selected character that provides females with information about the male genotype. 相似文献
2.
GL Baum 《Canadian Metallurgical Quarterly》1996,334(21):1404; author reply 1404-1404; author reply 1405
3.
In antenna design there are some fundamental relationships based on reciprocity. The equivalence of antenna pattern in transmission and reception is well known. Less well known is the time-derivative relationship going from reception to transmission. These relationships are derived here and expressed in various useful forms. Electric and magnetic dipoles are given special consideration, and the combined form constructed as a terminated TEM transmission line (the BTW antenna) is discussed for its transmission and reception properties 相似文献
4.
All leaders in health care today are charged with the responsibility of transforming present practices into new and different ones that are needed for the future. The structural side of transforming is ultimately easier than the human side. However, the most frequent failures come from not concentrating sufficiently on the behavioral side of the change. Structural and psychological change must occur simultaneously and embrace each other for best results. 相似文献
5.
Zupac D. Baum K.W. Kosier S.L. Schrimpf R.D. Galloway K.F. 《Electron Device Letters, IEEE》1991,12(10):546-549
The effect of noncatastrophic positive human body model (HBM) electrostatic discharge (ESD) stress on n-channel power MOSFETs is radically different from that on p-channel MOSFETs. In n-channel transistors, the stress causes negative shifts of the current-voltage characteristics indicative of positive charge trapping in the gate oxide. In p-channel transistors, the stress increases the drain-to-source leakage current, probably due to localized avalanche electron injection from the p-doped drain 相似文献
6.
Vladimir L. Solozhenko ‡ Vladimir Z. Turkevich§ Georg Will† 《Journal of the American Ceramic Society》1996,79(10):2798-2800
Peculiarities of the formation of BN in a self-propagating reaction between LiBF4 and Li3 N have been studied under a wide range of p,T conditions within the region of thermodynamic stability of cBN. Boron nitride crystallized mainly in the form of highly ordered hBN (1700–2100 K), of mesographitic BN (2200–3000 K), or of turbostratic BN (>3000 K). Cubic boron nitride was obtained with a low yield (up to 14 vol%) as a result of precipitation from the metastable eutectic liquid in the BN-Li3 N system. These results give further evidence for an alternative metastable behavior in the BN phase formation under high pressures. 相似文献
7.
Works of adhesion at the carbon fiber-liquid interface determined using a modified wetting technique
Works of adhesion WSL between aqueous solutions with pH values in the range from 1 to 14 and carbon fibers from different sources, which were additionally treated in an inert atmosphere or in oxygen, were measured by use of a microbalance. These works of adhesion WSL were found to show distinct stepwise dependencies on the pH value. The works of adhesion WSL are attributed to dispersion interactions WSL1 and various acid-base interactions wslab—in the latter case between the acidic and basic surface groups of carbon and the various basic and acidic aqueous solutions. 相似文献
8.
9.
The use of block coding and errors-and-erasures decoding can enhance performance in frequency-hop (FH) communication systems, provided that a good scheme is employed to determine which symbols to erase. The problem of making erasure decisions from collections of receiver outputs is investigated in this paper. Methods to determine which received symbols to erase are derived from Bayesian decision theory. Decision rules are developed for a system with M-ary orthogonal signaling, noncoherent demodulation, and frequency-selective fading. One result is a class of Bayesian schemes in which erasure decisions are made independently from symbol to symbol. Within this class is a rule that uses signal amplitude estimates for improved performance. A second result is a Bayesian technique in which erasure decisions are mutually dependent and are made collectively for each codeword. These techniques are analyzed and compared with the performance of receivers that use erasure techniques that require multiple applications of bounded distance decoding. The performance of the Bayesian techniques for dependent erasures are also compared with the performance of receivers that do not permit erasures. It is found that each of the Bayesian techniques offers substantial performance gains over errors-only decoding, and the dependent erasure scheme provides the best performance among the techniques of lower complexity 相似文献
10.
Folding of the collagen triple helix provides an opportunity to look at multichain molecular assembly. This triple helix also offers unique advantages for the study of folding because the process is very slow compared to globular proteins, and the kinetics of folding can be obtained in real time by NMR. Studies on triple-helical peptides illustrate the ability to observe kinetic folding intermediates directly and the ability to propose detailed mechanisms of folding through the use of real-time NMR methods. Defective collagen folding has been implicated in various connective tissue diseases and the capacity of NMR to look at the folding of specific sites provides a tool for obtaining information about altered folding mechanisms. Comparison of folding in peptides that model normal and diseased collagens could shed light on the molecular perturbation and the etiology of disease. 相似文献