Carbon Uptake Rates of Sea Ice Algae and Phytoplankton under Different Light Intensities in a Landfast Sea Ice Zone, Barrow, Alaska

To determine whether nitrogen or light exerts the most control for the rates of carbon production of ice algae and phytoplankton under the ice, nitrogen addition (NO3 or NH4) and light increment experiments were executed on the landfast sea ice of Barrow, Alaska, during the 2003 growing season by using a 13C-15N dual isotope tracer technique. The productivity of the bottom sea ice algae and phytoplankton at Barrow in 2003 was limited mainly by low light levels (approximately 0.3% of the surface irradiance) at the bottom under the snow-covered sea ice. The carbon and nitrate uptake rates of ice algae and phytoplankton increased as the incubation depth in the ice hole decreased and light intensity increased. In addition, under higher light conditions, the relative production of proteins of the bottom ice algae decreased, whereas the lipid proportion increased. The higher level of lipid synthesis of the ice algae might be significant to the nutrition of zooplankton and benthos because lipids are the most energy-dense biomolecules.Afin de déterminer si c’est l’azote ou la lumière qui exerce le plus grand contrôle sur les taux de production de carbone émanant des algues de glace et du phytoplancton sous la glace, des expériences consistant en l’ajout différentiel d’azote (NO3 ou NH4) et de lumière ont été effectuées sur la glace de mer côtière de Barrow, en Alaska, pendant la saison de croissance de 2003 grâce à une technique de traceurs d’isotopes mixtes de 13C-15N. La productivité des algues de glace de mer et de phytoplancton de fond à Barrow en 2003 a été surtout restreinte par les faibles taux de lumière (environ 0,3 % de l’éclairement de la surface) au fond, sous la glace de mer couverte de neige. Les taux d’absorption de carbone et d’azote chez les algues de glace et le phytoplancton augmentaient au fur et à mesure que la profondeur d’incubation du trou de glace diminuait et que l’intensité lumineuse s’intensifiait. De plus, lorsque les conditions de luminosité étaient plus grandes, la production relative de protéines des algues de glace de fond diminuait, tandis que la proportion de lipides grimpait. Le taux plus élevé de synthèse des lipides des algues de glace pourrait revêtir de l’importance dans la nutrition du zooplancton et du benthos parce que les lipides sont les biomolécules les plus denses en énergie

A Model for Selecting Technologies in New Product Development

Due to fast changing technologies, shortening product lifecycles, and increased global competition, companies today often need to develop new products continuously and faster. Successful introduction and acceleration of new product development (NPD) is important to obtain competitive advantage for companies. Since technology selection for NPD involves complex decision makings that are critical to the profitability and growth of a company, the selection of the most appropriate technology for a new product requires the use of a robust decision-making framework capable of evaluating several technology candidates based on multiple criteria. This paper presents an integrated model that adopts interpretive structural modeling (ISM) and fuzzy analytic network process (FANP) to evaluate various different available technologies for NPD. The ISM is used to understand the interrelationships among the factors, and the FANP is to facilitate the evaluation process of decision makers under an uncertain environment with interrelated factors. A case study of a flat panel manufacturer is performed to examine the practicality of the proposed model. The results show that the model can be applied for group decision making on the available technology evaluation and selection in new product development

Nearly Massless Electrons in the Silicon Interface with a Metal Film

We demonstrate the realization of nearly massless electrons in the most widely used device material, silicon, at the interface with a metal film. Using angle-resolved photoemission, we found that the surface band of a monolayer lead film drives a hole band of the Si inversion layer formed at the interface with the film to have nearly linear dispersion with an effective mass about 20 times lighter than bulk Si and comparable to graphene. The reduction of mass can be accounted for by repulsive interaction between neighboring bands of the metal film and Si substrate. Our result suggests a promising way to take advantage of massless carriers in silicon-based thin-film devices, which can also be applied for various other semiconductor devices.Comment: 4 pages, 4 figures, accepted for publication in Physical Review Letter

Temperature-scaling behavior of the Hall conductivity for Hg-based superconducting thin films

The Hall conductivities of HgBa_{2}CaCu_{2}O_{6+\delta}and HgBa_{2}Ca_{2}Cu_{3}O_{8+\delta} thin films are investigated for a magnetic field parallel to the c axis. The mixed-state Hall conductivity for these compounds is well described by \sigma_{xy}=C_{1}/H+C_{2}+C_{3}H. The prefactor C_1 shows a temperature dependence of the form C_1 = A(1-t)^n near T_c, where t=T/T_c is the reduced temperature. Contrary to the previous results, C_2 also follows a temperature-scaling behavior similar to that of the coefficient C_1. The observed value of n = 1.8 - 2.3 is comparable to the previously observed values for YBa_{2}Cu_{3}O_{7-\delta} and La_{2-x}Sr_{x}CuO_{4}.Comment: 5 pages, 4 eps figure

Effect of sintering temperature under high pressure in the uperconductivity for MgB2

We report the effect of the sintering temperature on the superconductivity of MgB2 pellets prepared under a high pressure of 3 GPa. The superconducting properties of the non-heated MgB2 in this high pressure were poor. However, as the sintering temperature increased, the superconducting properties were vastly enhanced, which was shown by the narrow transition width for the resistivity and the low-field magnetizations. This shows that heat treatment under high pressure is essential to improve superconducting properties. These changes were found to be closely related to changes in the surface morphology observed using scanning electron microscopy.Comment: 3 Pages including 3 figure

Singlet fermionic dark matter

We propose a renormalizable model of a fermionic dark matter by introducing a gauge singlet Dirac fermion and a real singlet scalar. The bridges between the singlet sector and the standard model sector are only the singlet scalar interaction terms with the standard model Higgs field. The singlet fermion couples to the standard model particles through the mixing between the standard model Higgs and singlet scalar and is naturally a weakly interacting massive particle (WIMP). The measured relic abundance can be explained by the singlet fermionic dark matter as the WIMP within this model. Collider implication of the singlet fermionic dark matter is also discussed. Predicted is the elastic scattering cross section of the singlet fermion into target nuclei for a direct detection of the dark matter. Search of the direct detection of the dark matter provides severe constraints on the parameters of our model.Comment: 12 pages, 7 figure

Universal scaling of the Hall resistivity in MgB2 superconductors

The mixed-state Hall resistivity and the longitudinal resistivity in superconducting MgB2 thin films have been investigated as a function of the magnetic field over a wide range of current densities from 100 to 10000 A/cm^2. We observe a universal Hall scaling behavior with a constant exponent of 2.0, which is independent of the magnetic field, the temperature, and the current density. This result can be interpreted well within the context of recent theories.Comment: 4 page