Syllinae (Syllidae: polychaeta) from the Mediterranean coast of Egypt with the description of two new species

This is the second paper dealing with the Syllidae collected on soft and hard bottom from the north-western coast of Egypt (Mediterranean Sea) and southern part of the Suez Canal. Eleven species were reported, two of them seem to be new to science, (Syllis sp.1 and Syllissp.2), but need further examination. Six species namely Opisthosyllis brunnea, Syllis columbretensis, Syllis gerlachi, Syllis ergeni, Syllis pulvinata andTrypanosyllis coeliaca were recorded as new for Egyptian waters

Dynamics of Uniform Quantum Gases, II: Magnetic Susceptibility

A general expression for temperature-dependent magnetic susceptibility of quantum gases composed of particles possessing both charge and spin degrees of freedom has been obtained within the framework of the generalized random-phase approximation. The conditions for the existence of dia-, para-, and ferro-magnetism have been analyzed in terms of a parameter involving single-particle charge and spin. The zero-temperature limit retrieves the expressions for the Landau and the Pauli susceptibilities for an electron gas. It is found for a Bose gas that on decreasing the temperature, it passes either through a diamagnetic incomplete Meissner-effect regime or through a paramagnetic-ferromagnetic large magnetization fluctuation regime before going to the Meissner phase at BEC critical temperature

Phase Space Reduction and the Instanton Crossover in (1+1)-Dimensional Turbulence

We study (1+1)-dimensional turbulence in the framework of the Martin-Siggia-Rose field theory formalism. The analysis is focused on the asymptotic behaviour at the right tail of the probability distribution function (pdf) of velocity differences, where shock waves do not contribute. A BRS-preserving scheme of phase space reduction, based on the smoothness of the relevant velocity fields, leads to an effective theory for a few degrees of freedom. The sum over fluctuations around the instanton solution is written as the expectation value of a functional of the time-dependent physical fields, which evolve according to a set of Langevin equations. A natural regularization of the fluctuation determinant is provided from the fact that the instanton dominates the action for a finite time interval. The transition from the turbulent to the instanton dominated regime is related to logarithmic corrections to the saddle-point action, manifested on their turn as multiplicative power law corrections to the velocity differences pdf.Comment: The revised version contains more detailed discussions on some technical point

A case study of the effects of gas and oil production on artificial reef and demersal fish and macrocrustacean communities in the northwestern Gulf of Mexico

This report provides a synthesis of the observed effects of the Buccanneer Gas and Oil Field on biological systems and fisheries of the study area. Demersal fishes and macrocrustaceans, the biofouling community, reef and pelagic fishes were used as indicators of impacts. Other biological components (bacteria, plankton and in-faunal benthos) were considered as part of the environment and were addressed only to the extent that they directly impacted or limited the primary indicator groups

The reaction of cytochrome c with [Fe(EDTA)(H2O)]−

AbstractThe interaction of horse ferricytochrome c with the reagents [Fe(EDTA)(H2O)]− and [Cr(CN)6]3− were studied at pH 7 and 25°C by 1H-NMR spectroscopy. Two binding regions near to the heme crevice of cytochrome c were identified. Both regions bound both reagents but they exhibited different selectivities.The relevance of this finding to the electron-transfer function of cytochrome c is discussed

Mapping the ultrafast flow of harvested solar energy in living photosynthetic cells

Photosynthesis transfers energy efficiently through a series of antenna complexes to the reaction center where charge separation occurs. Energy transfer in vivo is primarily monitored by measuring fluorescence signals from the small fraction of excitations that fail to result in charge separation. Here, we use two-dimensional electronic spectroscopy to follow the entire energy transfer process in a thriving culture of the purple bacteria, Rhodobacter sphaeroides. By removing contributions from scattered light, we extract the dynamics of energy transfer through the dense network of antenna complexes and into the reaction center. Simulations demonstrate that these dynamics constrain the membrane organization into small pools of core antenna complexes that rapidly trap energy absorbed by surrounding peripheral antenna complexes. The rapid trapping and limited back transfer of these excitations lead to transfer efficiencies of 83% and a small functional light-harvesting unit

Detuning effects in the one-photon mazer

The quantum theory of the mazer in the non-resonant case (a detuning between the cavity mode and the atomic transition frequencies is present) is written. The generalization from the resonant case is far from being direct. Interesting effects of the mazer physics are pointed out. In particular, it is shown that the cavity may slow down or speed up the atoms according to the sign of the detuning and that the induced emission process may be completely blocked by use of a positive detuning. It is also shown that the detuning adds a potential step effect not present at resonance and that the use of positive detunings defines a well-controlled cooling mechanism. In the special case of a mesa cavity mode function, generalized expressions for the reflection and transmission coefficients have been obtained. The general properties of the induced emission probability are finally discussed in the hot, intermediate and cold atom regimes. Comparison with the resonant case is given.Comment: 9 pages, 8 figure