A FLAVOPROTEIN IN Phycomyces blakesleeanus WITH SHORT FLUORESCENCE LIFETIME

Abstract— The photoreceptor system for the blue-light-induced phototropism in the fungus Phycomyces blakesleeanus includes one or more flavin chromophores, probably located in the plasma membrane of the sporangiophore. From a plasma-membrane fraction of short synchronous sporangiophores, we have enriched, by column chromatography, specific proteins with covalently bound flavins. These flavoproteins were analyzed by a fluorescence lifetime assay. Flavoproteins with fluorescence lifetimes significantly less than 5 ns have been predicted to be involved in blue-light reception. We studied samples from a wild type strain and from the night-blind mutant LI. (genotype madC). For the enriched flavoprotein samples, we found predominant fluorescent components with lifetimes of 1.5 ns (74%) for wild type and 1.8 ns (83%) for LI. According to this assay, one or both of these flavoproteins are likely components of the blue-light photoreceptor system in P. blakesleeanus.     

Time-Resolved Digital Image Correlation in the Scanning Electron Microscope for Analysis of Time-Dependent Mechanisms

Experimental Mechanics - Background: Advancements in the Digitial Image Correlation (DIC) technique over the past decade have greatly improved spatial resolution. However, many processes, such as...     

On Vacuum Fluctuations and Particle Masses

The idea that the mass m of an elementary particle is explained in the semi-classical approximation by quantum-mechanical zero-point vacuum fluctuations has been applied previously to spin-1/2 fermions to yield a real and positive constant value for m, expressed through the spinorial connection Γ _i in the curved-space Dirac equation for the wave function ψ due to Fock. This conjecture is extended here to bosonic particles of spin 0 and spin 1, starting from the basic assumption that all fundamental fields must be conformally invariant. As a result, in curved space-time there is an effective scalar mass-squared term , where R is the Ricci scalar and Λ _b is the cosmological constant, corresponding to the bosonic zero-point energy-density, which is positive, implying a real and positive constant value for m ₀, through the positive-energy theorem. The Maxwell Lagrangian density for the Abelian vector field F _ij ≡A _j,i −A _i,j is conformally invariant without modification, however, and the equation of motion for the four-vector potential A _i contains no mass-like term in curved space. Therefore, according to our hypothesis, the free photon field A _i must be massless, in agreement with both terrestrial experiment and the notion of gauge invariance.     

Pareto efficiency,simple game stability,and social structure in finitely repeated games

Simple game (sensu Brown and Vincent, 1987) evolutionary theory, when coupled with social structure measured as non‐random encounter of strategy “clones”, often permits equilibrium refinement leading to Pareto superior outcomes (e.g., Axelrod, 1981; Myerson et al., 1991), a foundational goal of economic game theory (Myerson, 1991: 370–375). This conclusion, derived from analyses of one‐shot and infinitely repeated games, fails for finitely repeated games. While mutant cluster invasion enhances Pareto efficiency of equilibria in the former, it can depress Pareto efficiency in the latter. Cooperative equilibria of finitely repeated games (under economic analysis) can be susceptible to cluster‐invasion by even more Pareto efficient strategies which are not themselves evolutionarily stable. Evolutionary (simple) game theory's ability to eliminate Pareto inferior Nash equilibrium strategies induces vulnerabilities foreign to economic analysis. Simple game analysis of finitely repeated games suggests that social structure, modeled as perennial invasion by mutant‐clusters, can induce cyclic invasion, saturation, and loss of cooperation.     

Syrian hamster embryo (SHE) assay (pH 6.7) coupled with infrared spectroscopy and chemometrics towards toxicological assessment

The Syrian hamster embryo (SHE) assay (pH 6.7) is an in vitro candidate to replace in vivo carcinogenicity tests. However, the conventional method of visual scoring of foci (non-transformed vs. transformed colonies) can be time-consuming and is open to subjectivity. Infrared (IR) spectroscopy has the potential to provide objective assessment of such SHE colonies with the added advantage of potentially providing mechanistic information. In this study, SHE cells were treated with one of eight different chemical regimens, allowed in culture to attach and form foci on IR-reflective glass slides; these were subsequently interrogated by attenuated total reflection (ATR) Fourier-transform IR (FTIR) spectroscopy. Derived mid-IR spectra (n = 13,406) were subjected to chemometric analysis focusing primarily on the extraction of biochemical information related to test agent treatment and/or morphological transformation. The use of ATR-FTIR spectroscopy with chemometrics to analyze the SHE assay is a novel approach to toxicological assessment.     

Determination of cerium in minerals with sulphanilic acid

Cerium can be determined colorimetrically in minerals with sulphanilic acid. Cerium(III) ions are oxidized with silver(II) in 1-7% sulphuric acid. Sulphanilic acid is oxidized by cerium(IV) ions in 20% sulphuric acid. The absorbance is determined at 540 nm. In the presence of maganese or chromium, cerium can be separated by precipitation as the oxalate. Lanthanum can be used as a gathering agent if necessary.     

Eine Methode zur Bestimmung des Schwefels in Sulfitablauge und organischen Verbindungen mittels Kaliumpermanganats

Ohne Zusammenfassung     

Spin and lifetime of the ω− hyperon

A total of 101 ω^? decays have been found in K^?p interactions at 10 and $\text{16 GeV}\text{c}$. The decay angular distribution has been fitted under the assumptions that the ω^? has spin either $\text{1}\text{2}\text{or}\text{3}\text{2}$. It has been found that the probability of isotropy (spin$\text{1}\text{2}\text{)}$ is less than one in a thousand, whereas the probability for spin $\text{3}\text{2}$ is about 70%. Thus, we exclude the spin $\text{1}\text{2}$ assignment. The lifetime of the ω^? is found to be (1.41_?0.24^+0.15) × 10^?10s, in agreement with our earlier result based on about $\text{1}\text{5}$ of the present sample.