Purity-bounded uncertainty relations in multidimensional space -- generalized purity

Uncertainty relations for mixed quantum states (precisely, purity-bounded position-momentum relations, developed by Bastiaans and then by Man'ko and Dodonov) are studied in general multi-dimensional case. An expression for family of mixed states at the lower bound of uncertainty relation is obtained. It is shown, that in case of entropy-bounded uncertainty relations, lower-bound state is thermal, and a transition from one-dimensional problem to multi-dimensional one is trivial. Results of numerical calculation of the relation lower bound for different types of generalized purity are presented. Analytical expressions for general purity-bounded relations for highly mixed states are obtained.Comment: 12 pages, 2 figures. draft version, to appear in J. Phys. A Partially based on a poster "Multidimensional uncertainty relations for states with given generalized purity" presented on X Intl. Conf. on Quantum Optics'2004 (Minsk, Belarus, May 30 -- June 3, 2004) More actual report is to be presented on ICSSUR-2005, Besan\c{c}on, France and on EQEC'05, Munich. V. 5: amended article after referees' remark

Laminar burning velocity of hybrid methane-iron-air flames

As widely acknowledged, it is mandatory to decarbonize our energy system. A low-cost opportunity to achieve this is with high energy density metal carriers. Renewable energy can be used to reduce metal oxides to metal. This metal can be stored under ambient conditions in the form of a powder and be combusted (=oxidised) whenever energy is needed, providing fully renewable heat. In this work, micron sized iron powder is considered as metal energy carrier and the effect of iron powder on the adiabatic burning velocity of methane-air flames is investigated for different mixtures. To do so the Heat Flux (HF) method is used to stabilize hybrid methane-iron-air flames on a perforated plate on which is heated at the rim. Thermocouples are connected at different distances from the center of the plate. This way, the change in adiabatic burning velocity of flames can be found by measuring the temperature gradient over the burner plate for different mixtures and gas velocities. Via a loadcell connected to a dispersion system, the iron powder mass flow is tracked. By combining the data from the loadcell with the thermocouples data the effect different powder loading for various gas mixtures on the burning velocity can be extracted. The challenges here are to supply the flame with a continuous and accurate mass flow of iron particles while also taking into account the dynamics of the created aerosol.<br/

The Heat Flux Method adapted for hybrid iron-methane-air flames

Recently a cyclic energy storage concept was proposed in which metal powders are used as CO2-free energy carrier: the metal fuel cycle. In this cycle, the burning of iron powder is considered as the discharge of the energy carrier. However, for this cycle to be a efficient one, more understanding of the laminar burning velocity of iron powder is needed. Therefore, a new burner - based on the Heat Flux Method (HFM) - is proposed which can measure the burning velocities of flat hybrid iron-methane-air flames. In this paper, this burner is described and a proof of burner is given by first results. Further analysis of these results show that the opportunities for improvement lay in limiting the fluctuations for iron-concentrations on small time scales

A forged ‘chimera’ including the second specimen of the protostegid sea turtle Santanachelys gaffneyi and shell parts of the pleurodire Araripemys from the Lower Cretaceous Santana Group of Brazil

Fossils of Cretaceous sea turtles adapted to an open marine lifestyle remain rare finds to date. Furthermore, the relationships between extant sea turtles, chelonioids, and other Mesozoic marine turtles are still contested, with one key species being Santanachelysgaffneyi Hirayama, 1998, long considered the earliest true sea turtle. The species is an Early Cretaceous member of Protostegidae, a controversial clade either placed within or closely related to Chelonioidea or, alternatively, along the stem lineage of hidden-neck turtles (Cryptodira) and representing an independent open marine radiation. Santanachelysgaffneyi is one of the most completely preserved early protostegids and is therefore critical for establishing the global phylogenetic position of the group. However, the single known specimen of this taxon is yet to be described in detail. Here we describe a second specimen of Santanachelysgaffneyi from its type horizon, the Romualdo Formation (late Aptian) of the Santana Group of the Araripe basin, NE Brazil. The skeletal elements preserved include the posterior part of the skull, neck vertebrae, shoulder girdle, anterior-most and left/central part of the carapace with few peripherals, and plastron lacking most of the hyoplastra. The remaining part of the carapace was apparently completed by fossil dealers using an anterior part of the pleurodiran Araripemydidae, tentatively identified as a shell portion of cf. Araripemysbarretoi, a more common Santana fossil turtle, among other indeterminate turtle shell fragments. The purpose of this paper is to report the repatriation of the specimen to Brazil and to provide a preliminary description