The role of robustness and changeability on the origin and evolution of genetic codes

We propose that an essential factor on the origin of genetic codes is a balanced accomplishment of robustness and changeability, two antithetical, but fundamental, properties for the survival and evolution of organisms. These measures are defined as the intrinsic properties of genetic codes. An evaluation of these properties explains the structural regularity of genetic codes, estimates the order of codon reassignment in deviant codes, and predicts the most probable deviant codes that exist. The enumeration of genetic codes that could have evolved from the standard genetic code under the selection pressure on robustness and changeability strongly limits the freedom of codon reassignments. The codon reassignments of all currently known deviant genetic codes belong to this predicted evolutionary path, and they generally give the highest improvements on robustness and changeability.     

Preparation and characteristics of Ni-ferrite powders obtained in the presence of fused salts

This paper describes Ni-ferrite formation in the presence of Li₂SO₄-Na₂SO₄ molten salts, and in particular the effects of the raw materials, amount of salts, heating temperature and time on the size and shape of the ferrite powders, as well as on the rate of ferrite formation. The molten salts accelerate ferrite formation and complete ferrite formation is attained at lower temperatures than in solid state reactions. Ferrite powders with two types of shapes are obtained from NiO with different particle sizes and aggregation states; one is similar to the starting Fe₂O₃ particles and the other has an octahedral crystal habit. The difference follows from the different dissolution rates of Fe₂O₃ and NiO. Growing particles in molten salts have a crystal habit, but the most stable particle shape is rounded.     

Factors determining drug residence in skin during transdermal absorption: studies on beta-blocking agents

A high rate of induction (9 of 10 cases) of human autologous cytotoxic T lymphocytes (CTL) was achieved in vitro from peripheral blood mononuclear cells of renal carcinoma patients by applying an interleukin (IL)-cocktail consisting of IL-1, -2, -4, and -6. The CTL specifically lysed their own target carcinoma cells within 24 h but did not kill neighboring autologous normal kidney cells or allogeneic renal cancer cell lines. In the case of TUHR4TKB, for which autologous CTL were not induced, no expression of MHC class-I molecules was observed on the surface of these carcinoma cells, although they were sensitive to autologous natural killer cells. The results imply that adoptive immunotherapy for metastasized renal carcinoma will be feasible with autologous CTL in combination with natural killer cells.     

Multiple mode locking of lasers

Details of experimental results on higher order phase-locking phenomena of a He-Ne laser with a fixed cavity length and a fixed position of the laser tube in the cavity are presented. Two methods have been used in the experiments in order to obtain high bit-rate optical pulses. In one method modified Michelson-type resonators and a three-mirror Fabry-Perot resonator are utilized to suppress the oscillation of the undesired modes. Optical pulses of repetition rates up to about 600 megabits/s have been obtained. The second method utilizes an internal phase perturbation in a conventional Fabry-Perot cavity at a frequency nearly equal to a multiple of the longitudinal mode spacing. The repetition rate of optical pulses generated does not always coincide with the modulation frequency, but depends on the fine tuning of the frequency. In contrast to the former method, mode quenching is not necessarily required to produce multiple-bit pulses.     

Linear differential games with terminal payoff

A linear differential game whose payoff is determined by a convex function of the state vector at a given terminal time is investigated. An explicit expression for the greatest lower bound of the value of the game is obtained. A simple condition which guarantees the existence of the value of the game is derived by a geometric approach. Under this condition, instead of solving the Bellman equation, the value of the game can be calculated by maximizing a function on the unit sphere of the output space whose dimension is usually much less than that of the state space. The method of synthesizing the optimal strategies is also derived. Another game called a minimax energy game whose payoff is given by the difference between the consumed energies of both players is treated briefly, and an extension of the concept of controllability is discussed.     

Silicon implanted super low-noise GaAs MESFET

Super low-nose GaAs MESFETs have been fabricated using direct ion implantation into undoped LEC substrates. Microwave results at 12 GHz include a noise figure of 1.3 dB, with an associated gain of 10.3 dB and a maximum available gain of 14.9 dB.     

Analysis of irreversible circulation in reactor noise

A new parameter is proposed as a statistical variable of multi-dimensional reactor noise analysis. It indicates circulation in a space of state variables, while the well-known variance σ represents the spread of distribution of fluctuations. The pair of quantities σ and are minimum necessary integral indices to characterize any power spectral density and are convenient for data retrieval. The is less sensitive to the effect of low-cut filter than σ. The analysis of experimental data by using is demonstrated and compared with the results of theoretical treatment.     

Characteristics of germanium avalanche photodiodes in the wavelength region of 1-1.6 µm

Dark current, quantum efficiency, multiplication noise, and pulse response of germanium avalanche photodiodes with n+-p junction were studied to find an optimum structure. The dark current can be separated by graphical means into a leakage current component and a multiplied component which flows through the junction. The dark current components are also evaluated by using diodes with various diameters. The quantum efficiency and the multiplication noise are shown to be strongly affected by the n+ layer thickness. An n+ layer thickness optimized for signal-to-noise ratio is estimated from experimental and calculated results, using a figure of merit for avalanche photodiodes. The response waveform for mode-locked Nd:YAG laser shows a rise time of 100 ps and a half pulsewidth of less than 200 ps.