The laminar burning velocity of flames propagating in mixtures of hydrocarbons and air measured with the heat flux method

The heat flux method for stabilizing flat adiabatic flames and measuring adiabatic burning velocities is reviewed. The latest improvements of the burner construction and analysis of the measurements are presented and a reliable error estimate is deduced. A consistent and reliable set of burning velocities has been measured for a range of fuels: new results for the adiabatic burning velocities of mixtures of methane, ethane, propane, n-butane, and isobutane with air are presented, including error bars of 95% confidence intervals. The influence of variations of initial temperature on the burning velocity of mixtures of methane and air has also been studied. The results are compared with other measurements using the heat flux, counterflow, and combustion vessel methods. It seems that results for the burning velocity using different methods converge toward each other. For stoichiometric flames of methane and air this value seems to be close to 36 cm/s, while the differences between the results of different techniques do not vary by more than roughly 1 cm/s.     

Study of the IC443 SNR with the Fermi LAT

During the first six months of data taking the Fermi satellite was capable to detect gamma ray emission of the nearby supernova remnant IC443 (G189.1+3.0). IC443 is a shell-type supernova remnant located in the anticenter region where observation can be made clean enough from possible foreground and background overlap, even though care has to be taken due to the vicinity of one of the brightest gamma-ray pulsars, Geminga. IC443 estimated age (20–30 kyr) and the observed two-shell morphology with different radii suggest that the SNR shell has been interacting with surrounding interstellar matter and a neighboring SNR shell. Also the detection of strong molecular emission lines and TeV gamma-ray emission support the idea that the blast has been interacting with dense molecular gas accelerating cosmic-ray particle. After the first year of data taking, Fermi will be surely capable to determine the spatial extension and resolve in much finer details the spectral shape of the gamma-ray emission produced by the accelerated cosmic rays in IC443 distinguished from those of galactic origin.     

Analysis of the FIC detector data at the n_TOF facility

Fission cross-section measurements with the Fast Ionization Chamber (FIC) at the CERN n_TOF facility were challenged by intense signals due to γ-rays and ultra-relativistic particles from the impact of the 20 GeV proton pulses on the neutron spallation target. A method for analyzing the data taken with Flash Analog to Digital Converters (FADC) was developed to treat these problems in an automated way to provide a reliable background subtraction and a fit routine for identifying fission events even at high energies. The analysis is illustrated at the example of the fission cross-section of ²³⁸U relative to that of ²³⁵U in the energy range from 40 keV to 300 MeV.     

Response of the GLAST LAT calorimeter to relativistic heavy ions

The CsI calorimeter of the Gamma-Ray Large-Area Space Telescope (GLAST) will be calibrated in flight with cosmic-ray heavy ions. In order to determine the response of the calorimeter to relativistic heavy ions lighter than Fe, an experiment was carried out at the GSI heavy ion facility using the Fragment Separator (FRS). The measured response exhibits an unexpected feature for light ions, opposite to that observed at low incident energy: for a given deposited energy, the observed signal is greater for these ions than for protons (or more generally Z=1 minimum ionizing particles). Pulse shapes are found to be almost identical for carbon ions and Z=1 particles, with a significant slow scintillation component, which constitutes another departure from the low-energy behavior. Data on the energy resolution for the individual CsI crystals and on the loss of ions due to nuclear reactions in the calorimeter are also presented.     

Dark matter annihilations search in dwarf spheroidal galaxies with fermi

Launched in June 2008, the Fermi Gamma-ray Telescope includes a pair conversion detector designed for the 20 MeV to gamma-ray sky study, the Large Area Telescope (LAT). Operating in all-sky survey mode, its excellent sensitivity and angular resolution will allow either to discover or constrain a signal coming through the annihilation of dark matter particles. Predicted by cold dark matter scenarios as the largest clumps, dwarf spheroidal galaxies are amongst the most attractive targets for indirect search of dark matter by gamma-ray experiments. We present here an overview of the Fermi LAT Dark Matter and New Physics Working Group efforts in the searches of gamma-ray fluxes coming from WIMP pair annihilations in dwarf spheroidal galaxies.     

19’号花园 蓝色的生物多样性

这个花园是植物不同鲜艳颜色的变种。它展示了植物的多样性和不同深浅度蓝色的无限多样性。花园中精心布置的彩石,宛若彩色的台阶,层层展开,与植物互相呼应。     

Etude du transfert DE Cd, Pb, Cu ET Zn dans les chaines trophiques neritiques et estuariennes—I. Etat dans l'estuaire interne de la loire (France) au cours de l'ete 1978

In order to determine the behaviour of some trace elements (Cd, Pb, Cu, Zn) in estuarine biota, different species of crustaceans and fishes were taken up from the Loire estuary. The concentrations of metals were determined by atomic absorption.Except for Zn, the accumulation of metals is higher in crustaceans than in fishes and the phenomenon is particularly important for copper, a constituent of crustaceans respiratory pigment. The concentrations of metals are no more important for bottom-feeders than for other fishes. The highest levels are encountered for Zn followed by Cu, Pb and Cd. The Loire organisms are not so contaminated than those of the same species taken up from heavily polluted estuaries (Severn and Medway, G.-B.).Transfers in food chains were quantified with the transfer factor: f.t. = Concentration in the consumer/Concentration in the prey.For Cd, Pb and Cu, the transfer factor is generally inferior to 1, attaining exceptionally 2.01. Except in one case, it is higher than 1 for Zn. The concentration of trace elements in intestine content is higher than in stomach content, probably as a consequence of faeces enrichment by unassimilated metals. So, there is probably no biomagnification in estuarine food chain for Cd, Pb and Cu, the case of Zn being more ambiguous.     

转角遇到爱

百叶居那一年,青涩的年纪,平常的日子,你走在狭小的街道上,正想着自己的事。余晖里是葡萄牙平常人家的屋面,冷不丁与牵着怪怪宠物的邻居碰个满怀,     

Etude du transfert de Cd, Pb, Cu et Zn dans les chaines trophiques neritiques et estuariennes—II. Accumulation biologique chez les poissons planctonophages

Plankton-feeder fish and their preys (mainly Copepods and Mysids) were obtained from the Loire estuary (France). Trace elements (Cd, Pb, Cu, Zn) concentrations in organisms from different steps in the food chain were compared using the transfer factor:It is generally lower than 1 for Cd, Pb and Cu but often higher than 1 for Zn. Before interpreting this last data as a consequence of biomagnification of Zn in food chain, we have to emphasize that the level of Zn in the predator, used for the calculation of f.t., results of accumulation from both food and water.During the digestion, we often observed a light decrease of metal concentrations between prey and stomach content followed by an increase of the metal levels in intestine content compared to stomach.     

Isomer separation of Cu and Cu with a resonance ionization laser ion source

Radioactive copper isotopes were ionized with the resonance ionization laser ion source (RILIS) at the on-line isotope separator ISOLDE (CERN). Using the different hyperfine structure in the 3d¹⁰ 4s  ²S_1/2 – 3d¹⁰ 4p  ²P⁰_1/2 transition the low- and high-spin isomers of ⁷⁰Cu were selectively enhanced by tuning the laser wavelength. The light was provided by a narrow-bandwidth dye laser pumped by copper vapor lasers (CVL) and frequency doubled in a BBO crystal. The ground state to isomeric state intensity ratio could be varied by a factor of 30, allowing to assign gamma transitions unambiguously to the decay of the individual isomers. It is shown that the method can also be used to determine magnetic moments. In a first experiment for the 1⁺ ground state of ⁷⁰Cu a magnetic moment of (+)1.8(3) μ_N and for the high-spin isomer of ⁷⁰Cu a magnetic moment of (±)1.2(3) μ_N could be deduced.