Search results for "mass [rho(770)]"
showing 10 items of 416 documents
Influence of Nutrients and Mixing on the Primary Production and Community Respiration in the Gulf of Riga
1999
Abstract Rates of plankton community production and respiration in relation to wind, solar radiation, biomass and nutrients were measured in the mixed layer during a late spring, a mid-summer and an early autumn situation in the Gulf of Riga. System metabolism was estimated by the in vitro oxygen method and from oxygen mass balance directly in the water. Gross production (GPP) remained fairly stable throughout the investigation periods with a mean of 1.8 g C m−2 day−1 (range: 0.5–3.9 g C m−2 day−1). Community respiration varied from 0.5 to 6.4 g C m−2 day−1 during the two summer studies (the high respiration rates ranging from 3.0 to 10.4 g C m−2 day−1 found during the autumn cruise were pr…
Global distributions of diazotrophs Gamma-A nifH genes abundance - Depth integrated values computed from a collection of source datasets - Contributi…
2013
The MAREDAT atlas covers 11 types of plankton, ranging in size from bacteria to jellyfish. Together, these plankton groups determine the health and productivity of the global ocean and play a vital role in the global carbon cycle. Working within a uniform and consistent spatial and depth grid (map) of the global ocean, the researchers compiled thousands and tens of thousands of data points to identify regions of plankton abundance and scarcity as well as areas of data abundance and scarcity. At many of the grid points, the MAREDAT team accomplished the difficult conversion from abundance (numbers of organisms) to biomass (carbon mass of organisms). The MAREDAT atlas provides an unprecedente…
Superconducting Solenoid System with Adjustable Shielding Factor for Precision Measurements of the Properties of the Antiproton
2019
Physical review applied 12(4), 044012 (2019). doi:10.1103/PhysRevApplied.12.044012
A DERIVATION OF THE VLASOV-NAVIER-STOKES MODEL FOR AEROSOL FLOWS FROM KINETIC THEORY
2016
This article proposes a derivation of the Vlasov-Navier-Stokes system for spray/aerosol flows. The distribution function of the dispersed phase is governed by a Vlasov-equation, while the velocity field of the propellant satisfies the Navier-Stokes equations for incompressible fluids. The dynamics of the dispersed phase and of the propellant are coupled through the drag force exerted by the propellant on the dispersed phase. We present a formal derivation of this model from a multiphase Boltzmann system for a binary gaseous mixture, involving the droplets/dust particles in the dispersed phase as one species, and the gas molecules as the other species. Under suitable assumptions on the colli…
The invasive seaweed Asparagopsis taxiformis erodes the habitat structure and biodiversity of native algal forests in the Mediterranean Sea
2021
Abstract Invasive seaweeds are listed among the most relevant threats to marine ecosystems worldwide. Biodiversity hotspots, such as the Mediterranean Sea, are facing multiple invasions and are expected to be severely affected by the introduction of new non-native seaweeds in the near future. In this study, we evaluated the consequences of the shift from the native Ericaria brachycarpa to the invasive Asparagopsis taxiformis habitat on the shallow rocky shores of Favignana Island (Egadi Islands, MPA, Sicily, Italy). We compared algal biomass and species composition and structure of the associated epifaunal assemblages in homogenous and mixed stands of E. brachycarpa and A. taxiformis. The r…
Optimum Carrier Concentration in n-Type PbTe Thermoelectrics
2014
Taking La- and I-doped PbTe as an example, the current work shows the effects of optimizing the thermoelectric figure of merit, zT, by controlling the doping level. The high doping effectiveness allows the carrier concentration to be precisely designed and prepared to control the Fermi level. In addition to the Fermi energy tuning, La-doping modifies the conduction band, leading to an increase in the density of states effective mass that is confirmed by transport, infrared reflectance and hard X-ray photoelectron spectroscopy measurements. Taking such a band structure modification effect into account, the electrical transport properties can then be well-described by a self-consistent single…
Optimization of the carrier concentration in phase-separated half-Heusler compounds
2014
Inspired by the promising thermoelectric properties of phase-separated half-Heusler materials, we investigated the influence of electron doping in the n-type Ti_(0.3−x)Zr_(0.35)Hf_(0.35)NiSn compound. The addition of Nb to this compound led to a significant increase in its electrical conductivity, and shifted the maximum Seebeck coefficient to higher temperatures owing to the suppression of intrinsic carriers. This resulted in an enhancement of both the power factor α^2σ and figure of merit, zT. The applicability of an average effective mass model revealed the optimized electron properties for samples containing Nb. There is evidence in the literature that the average effective mass model i…
A Penning Trap for Studying Cluster Ions
1986
We propose to use a Penning trap for spectroscopy of stored cluster ions. A similar device has been built for the purpose of mass measurements of short-lived nuclei produced at the on-line isotope separator ISOLDE/CERN. A resolving power of 500,000 in a mass measurement of39K and an accuracy of 2 × 10−7 for the85Rb/39K mass ratio were obtained. An efficiency for in-flight capture as high as 70% was achieved. The method provides very high sensitivity since typically only 10 to 100 ions are stored in the trap. We intend to perform laser spectroscopy on trapped Na clusters as a first application of the trap technique.
Photoluminescence study of excitons in homoepitaxial GaN
2001
High-resolution photoluminescence spectra have been measured in high-quality homoepitaxial GaN grown on a free-standing GaN substrate with lower residual strain than in previous work. Unusually strong and well-resolved excitonic lines were observed. Based on free- and bound exciton transitions some important GaN parameters are derived. The Arrhenius plot of the free A exciton recombination yields a binding energy of 24.7 meV. Based on this datum, an accurate value for the band-gap energy, EG(4.3 K) = 3.506 eV, can be given. From the donor bound excitons and their “two-electron” satellites, the exciton localization energy and donor ionization energy are deduced. Finally, estimates of the ele…
Impact of nitrogen doping on the band structure and the charge carrier scattering in monolayer graphene
2021
The addition of nitrogen as a dopant in monolayer graphene is a flexible approach to tune the electronic properties of graphene as required for applications. Here, we investigate the impact of the doping process that adds N dopants and defects on the key electronic properties, such as the mobility, the effective mass, the Berry phase, and the scattering times of the charge carriers. Measurements at low temperatures and magnetic fields up to 9 T show a decrease of the mobility with increasing defect density due to elastic, short-range scattering. At low magnetic fields weak localization indicates an inelastic contribution depending on both defects and dopants. Analysis of the effective mass …