Haemoglobin and size dependent constraints on swimbladder inflation in fish larvae

In developmental studies of fish species (especially physostomians) it could be demonstrated, that the lack of haemoglobin during larval and juvenile stages is a relatively common phenomenon. Generally it is linked with body translucency. In representatives of the families Galaxiidae, Osmeridae and Clupeidae, partly reared, partly observed immediately after being caught in the wild, it turned out, that this condition coincides with a considerable delay in swimbladder inflation. To determine the moment of its first inflation, larvae placed in a hermetic chamber were observed under a dissecting microscope. While lowering the pressure, the expanding swimbladder showed whether or not its content is really gaseous. The reason postulated to be responsible for the delayed inflation is that larvae lacking haemoglobin do not have the possibility of oxygen transport to their buoyancy organ by means of the blood. Apart of this, capillarity force calculations and body force estimations show that with decreasing size the constraints linked with surface tension increase overproportionally. While in larger sized larvae like trout we could demonstrate inflation by swallowing air, in species with small larvae this was not the case. Below a certain size, even in physostomians, the ductus pneumaticus is no alternative to the blood pathway for swimbladder inflation

Variational bound on energy dissipation in turbulent shear flow

We present numerical solutions to the extended Doering-Constantin variational principle for upper bounds on the energy dissipation rate in plane Couette flow, bridging the entire range from low to asymptotically high Reynolds numbers. Our variational bound exhibits structure, namely a pronounced minimum at intermediate Reynolds numbers, and recovers the Busse bound in the asymptotic regime. The most notable feature is a bifurcation of the minimizing wavenumbers, giving rise to simple scaling of the optimized variational parameters, and of the upper bound, with the Reynolds number.Comment: 4 pages, RevTeX, 5 postscript figures are available as one .tar.gz file from [email protected]

Stochastic Resonance in a simple model of magnetic reversals

We discuss the effect of stochastic resonance in a simple model of magnetic reversals. The model exhibits statistically stationary solutions and bimodal distribution of the large scale magnetic field. We observe a non trivial amplification of stochastic resonance induced by turbulent fluctuations, i.e. the amplitude of the external periodic perturbation needed for stochastic resonance to occur is much smaller than the one estimated by the equilibrium probability distribution of the unperturbed system. We argue that similar amplifications can be observed in many physical systems where turbulent fluctuations are needed to maintain large scale equilibria.Comment: 6 page

Generation and Structure of Solitary Rossby Vortices in Rotating Fluids

The formation of zonal flows and vortices in the generalized Charney-Hasegawa-Mima equation is studied. We focus on the regime when the size of structures is comparable to or larger than the deformation (Rossby) radius. Numerical simulations show the formation of anticyclonic vortices in unstable shear flows and ring-like vortices with quiescent cores and vorticity concentrated in a ring. Physical mechanisms that lead to these phenomena and their relevance to turbulence in planetary atmospheres are discussed.Comment: 3 pages in REVTeX, 5 postscript figures separately, submitted to Phys. Rev.

Emergence of pointer states in a non-perturbative environment

We show that the pointer basis distinguished by collisional decoherence consists of exponentially localized, solitonic wave packets. Based on the orthogonal unraveling of the quantum master equation, we characterize their formation and dynamics, and we demonstrate that the statistical weights arising from an initial superposition state are given by the required projection. Since the spatial width of the pointer states can be obtained by accounting for the gas environment in a microscopically realistic fashion, one may thus calculate the coherence length of a strongly interacting gas.Comment: 8 pages, 1 figure; corresponds to published versio

Rubrobacter aplysinae sp. nov., isolated from the marine sponge Aplysina aerophoba

A Gram-stain-positive, non-spore-forming bacterium (strain RV113(T)) was isolated from the marine sponge Aplysina aerophoba. 16S rRNA gene sequence analysis showed that strain RV113(T) belongs to the genus Rubrobacter, and is related most closely to Rubrobacter bracarensis VF70612_S1(T) (96.9% similarity) and more distantly related (<93%) to all other species of the genus Rubrobacter. The peptidoglycan diamino acid was lysine. Strain RV113(T) exhibited a quinone system with menaquinone MK-8 as the predominant compound. The polar lipid profile of strain RV113(T) consisted of the major compounds phosphatidylglycerol and two unidentified phosphoglycolipids. The major fatty acid was anteiso-C17 : 0ω9c. These chemotaxonomic traits are in agreement with those of other species of the genus Rubrobacter. The results of physiological and biochemical tests allowed the clear phenotypic differentiation of strain RV113(T) from all recognized Rubrobacter species. Strain RV113(T) is thus considered to represent a novel species, for which the name Rubrobacter aplysinae sp. nov. is proposed. The type strain is RV113(T) ( = DSM 27440(T) = CECT 8425(T))

A compendium of NASA Aerobee sounding rocket launchings for 1966

Compendium of Aerobee sounding rocket launchings for 196