4,481 research outputs found
Edge technique for measurement of laser frequency shifts including the Doppler shift
A method is disclosed for determining the frequency shift in a laser system by transmitting an outgoing laser beam. An incoming laser beam having a frequency shift is received. A first signal is acquired by transmitting a portion of the incoming laser beam to an energy monitor detector. A second signal is acquired by transmitting a portion of the incoming laser beam through an edge filter to an edge detector, which derives a first normalized signal which is proportional to the transmission of the edge filter at the frequency of the incoming laser beam. A second normalized signal is acquired which is proportional to the transmission of the edge filter at the frequency of the outgoing laser beam. The frequency shift is determined by processing the first and second normalized signals
Biogenesis of Cytochrome c in Neurospora crassa
# 1.
Precipitating antibodies specific for apocytochrome c and holocytochrome c, respectively, were employed to study synthesis and intracellular transport of cytochrome c in Neurospora in vitro.
# 2.
Apocytochrome c as well as holocytochrome c were found to be synthesized in a cell-free homogenate. A precursor product relationship between the two components is suggested by kinetic experiments.
# 3.
Apocytochrome c synthesized in vitro was found in the post-ribosomal fraction and not in the mitochondrial fraction, whereas holocytochrome c synthesized in vitro was mainly detected in the mitochondrial fraction. A precursor product relationship between postribosomal apocytochrome c and mitochondrial holocytochrome c is indicated by the labelling data. In the microsomal fraction both apocytochrome c and holocytochrome c were found in low amounts. Their labelling kinetics do not suggest a precursor role of microsomal apocytochrome c or holocytochrome c.
# 4.
Formation of holocytochrome c from apocytochrome c was observed when postribosomal supernatant containing apocytochrome c synthesized in vitro was incubated with isolated mitochondria, but not when incubated in the absence of mitochondria. The cytochrome c formed under these conditions was detected in the mitochondria.
# 5.
Conversion of labelled apocytochrome c synthesized in vitro to holocytochrome c during incubation of a postribosomal supernatant with isolated mitochondria was inhibited when excess isolated apocytochrome c, but not when holocytochrome c was added.
# 6.
The data presented are interpreted to show that apocytochrome c is synthesized on cytoplasmic ribosomes and released into the supernatant. It is suggested that apocytochrome c migrates to the inner mitochondrial membrane, where the heme group is covalently linked to the apoprotein. The hypothesis is put forward that the concomitant change in conformation leads to trapping of holocytochrome c in the membrane. The probles of permeability of the outer mitochondrial membrane to apocytochrome c and the site and nature of the reaction by which the heme group is linked to the apoprotein are discussed
Analytic treatment of nuclear spin-lattice relaxation for diffusion in a cone model
We consider nuclear spin-lattice relaxation rate resulted from a diffusion
equation for rotational wobbling in a cone. We show that the widespread point
of view that there are no analytical expressions for correlation functions for
wobbling in a cone model is invalid and prove that nuclear spin-lattice
relaxation in this model is exactly tractable and amenable to full analytical
description. The mechanism of relaxation is assumed to be due to dipole-dipole
interaction of nuclear spins and is treated within the framework of the
standard Bloemberger, Purcell, Pound - Solomon scheme. We consider the general
case of arbitrary orientation of the cone axis relative the magnetic field. The
BPP-Solomon scheme is shown to remain valid for systems with the distribution
of the cone axes depending only on the tilt relative the magnetic field but
otherwise being isotropic. We consider the case of random isotropic orientation
of cone axes relative the magnetic field taking place in powders. Also we
consider the cases of their predominant orientation along or opposite the
magnetic field and that of their predominant orientation transverse to the
magnetic field which may be relevant for, e.g., liquid crystals. Besides we
treat in details the model case of the cone axis directed along the magnetic
field. The latter provides direct comparison of the limiting case of our
formulas with the textbook formulas for free isotropic rotational diffusion.
The dependence of the spin-lattice relaxation rate on the cone half-width
yields results similar to those predicted by the model-free approach.Comment: 29 p., 7 fig. arXiv admin note: substantial text overlap with
arXiv:1101.249
Digital Genesis: Computers, Evolution and Artificial Life
The application of evolution in the digital realm, with the goal of creating
artificial intelligence and artificial life, has a history as long as that of
the digital computer itself. We illustrate the intertwined history of these
ideas, starting with the early theoretical work of John von Neumann and the
pioneering experimental work of Nils Aall Barricelli. We argue that
evolutionary thinking and artificial life will continue to play an integral
role in the future development of the digital world.Comment: Extended abstract of talk presented at the 7th Munich-Sydney-Tilburg
Philosophy of Science Conference: Evolutionary Thinking, University of
Sydney, 20-22 March 2014. Presentation slides from talk available at
http://www.tim-taylor.com/papers/digital-genesis-presentation.pd
Method of and apparatus for measuring temperature and pressure
Laser beams are transmitted through gas to a reflecting target, which may be either a solid surface or particulate matter in gas or the gas molecules. The return beams are measured to determine the amount of energy absorbed by the gas. For temperature measurements, the laser beam has a wavelength at which the gas exhibits a relatively temperature sensitive and pressure insensitive absorption characteristic for pressure measurements, the laser beam has a wavelength at which the gas has a relatively pressure sensitive and temperature insensitive absorption characteristic. To reduce the effects of scattering on the absorption measurements a reference laser beam with a weak absorption characteristic is transmitted colinearly with the data beam having a strong absorption characteristic. The two signals are processed as a ratio to eliminate back scattering. Embodiments of transmitters and receivers described include a sequential laser pulse transmitter and receiver, a simultaneous laser pulse transmitter and receiver
Ocean properties
The author has identified the following significant results. Results of testing the CP program indicate that the best results can be obtained in the near infrared water bands. The absorption due to water vapor and carbon dioxide in the thermal infrared band appeared to be less reliable in comparison to spacecraft-acquired data and band models. Comparisons of laboratory carbon dioxide transmission in the thermal infrared band show good agreement except in regions where lines are known to be missing. The comparison of ozone transmission at a wavelength of 9.6 micrometers to laboratory data showed unexceptedly large differences
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