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

Solid-state metathesis reactions under pressure: A rapid route to crystalline gallium nitride

High pressure chemistry has traditionally involved applying pressure and increasing temperature until conditions become thermodynamically favorable for phase transitions or reactions to occur. Here, high pressure alone is used as a starting point for carrying out rapid, self-propagating metathesis reactions. By initiating chemical reactions under pressure, crystalline phases, such as gallium nitride, can be synthesized which are inaccessible when initiated from ambient conditions. The single-phase gallium nitride made by metathesis reactions under pressure displays significant photoluminescence intensity in the blue/ultraviolet region. The absence of size or surface-state effects in the photoluminescence spectra show that the crystallites are of micron dimensions. The narrow lines of the x-ray diffraction patterns and scanning electron microscopy confirm this conclusion. Brightly luminescent thin films can be readily grown using pulsed laser deposition

The Globular Cluster System of M60 (NGC 4649). I. CFHT MOS Spectroscopy and Database

We present the measurement of radial velocities for globular clusters in M60, giant elliptical galaxy in the Virgo cluster. Target globular cluster candidates were selected using the Washington photometry based on the deep 16\arcmin \times 16\arcmin images taken at the KPNO 4m and using the $VI$ photometry derived from the HST/WFPC2 archive images. The spectra of the target objects were obtained using the Multi-Object Spectrograph (MOS) at the Canada-France-Hawaii Telescope (CFHT). We have measured the radial velocity for 111 objects in the field of M60: 93 globular clusters (72 blue globular clusters with $1.0\le(C-T_1)<1.7$ and 21 red globular clusters with $1.7\le(C-T_1)<2.4$), 11 foreground stars, 6 small galaxies, and the nucleus of M60. The measured velocities of the 93 globular clusters range from $\sim 500$ km s$^{-1}$ to $\sim 1600$ km s$^{-1}$, with a mean value of $1070_{-25}^{+27}$ km s$^{-1}$, which is in good agreement with the velocity of the nucleus of M60 ($v_{\rm gal}=1056$ km s$^{-1}$). Combining our results with data in the literature, we present a master catalog of radial velocities for 121 globular clusters in M60. The velocity dispersion of the globular clusters in the master catalog is found to be $234_{-14}^{+13}$ km s$^{-1}$ for the entire sample, $223_{-16}^{+13}$ km s$^{-1}$ for 83 blue globular clusters, and $258_{-31}^{+21}$ km s$^{-1}$ for 38 red globular clusters.Comment: 29 pages, 8 figures. To appear in Ap

Damage Proxy Map from Interferometric Synthetic Aperture Radar Coherence

A method, apparatus, and article of manufacture provide the ability to generate a damage proxy map. A master coherence map and a slave coherence map, for an area prior and subsequent to (including) a damage event are obtained. The slave coherence map is registered to the master coherence map. Pixel values of the slave coherence map are modified using histogram matching to provide a first histogram of the master coherence map that exactly matches a second histogram of the slave coherence map. A coherence difference between the slave coherence map and the master coherence map is computed to produce a damage proxy map. The damage proxy map is displayed with the coherence difference displayed in a visually distinguishable manner

Ordered Phases of Itinerant Dzyaloshinsky-Moriya Magnets and Their Electronic Properties

A field theory appropriate for magnets that display helical order due to the Dzyaloshinsky-Moriya mechanism, a class that includes MnSi and FeGe, is used to derive the phase diagram in a mean-field approximation. The helical phase, the conical phase in an external magnetic field, and recent proposals for the structure of the A-phase and the non-Fermi-liquid region in the paramagnetic phase are discussed. It is shown that the orientation of the helical pitch vector along an external magnetic field within the conical phase occurs via two distinct phase transitions. The Goldstone modes that result from the long-range order in the various phases are determined, and their consequences for electronic properties, in particular the specific heat, the single-particle relaxation time, and the electrical and thermal conductivities, are derived. Various aspects of the ferromagnetic limit, and qualitative differences between the transport properties of helimagnets and ferromagnets, are also discussed.Comment: 22pp, 8 eps fig

Numerical renormalization group study of the symmetric Anderson-Holstein model: phonon and electron spectral functions

We study the symmetric Anderson-Holstein (AH) model at zero temperature with Wilson's numerical renormalization group (NRG) technique to study the interplay between the electron-electron and electron-phonon interactions. An improved method for calculating the phonon propagator using the NRG technique is presented, which turns out to be more accurate and reliable than the previous works in that it calculates the phonon renormalization explicitly and satisfies the boson sum rule better. The method is applied to calculate the renormalized phonon propagators along with the electron propagators as the onsite Coulomb repulsion $U$ and electron-phonon coupling constant $g$ are varied. As $g$ is increased, the phonon mode is successively renormalized, and for $g \gtrsim g_{co}$ crosses over to the regime where the mode splits into two components, one of which approaches back to the bare frequency and the other develops into a soft mode. The initial renormalization of the phonon mode, as $g$ is increased from 0, depends on $U$ and the hybridization $\Delta$; it gets softened (hardened) for $U \gtrsim (\lesssim) U_s (\Delta)$. Correlated with the emergence of the soft mode is the central peak of the electron spectral function severely suppressed. These NRG calculations will be compared with the standard Green's function results for the weak coupling regime to understand the phonon renormalization and soft mode.Comment: 18 pages, 4 figures. Submitted to Phys. Rev.

In Vitro and in Vivo Phototoxicity on Gastric Mucosa Induced by Methylene Blue

BACKGROUND: Methylene blue (MB) is used endoscopically to demarcate tumors and as a photosensitizer in photodynamic therapy (PDT). However, there are few in vivo studies about its toxicity in healthy stomach tissue. We performed sequential in vitro and in vivo analyses of MB-induced phototoxicity. METHODS: We performed in vitro experiments using the AGS human gastric cancer cell line treated with light-emitting diode (LED) irradiation (3.6 J/cm RESULTS: In vitro, increased concentrations of MB led to higher TUNEL scores. However, cell viability was significantly lower after MB plus LED irradiation than after treatment with MB alone (P \u3c 0.001). In vivo, the TUNEL score was highest immediately after treatment with 0.1% or 0.5% MB plus light irradiation, and the score was significantly higher in the LED illumination plus MB group than in the control group (P \u3c 0.05). The elevated TUNEL score was maintained for 3 days in the MB plus light irradiation group but returned to normal levels on day 10. CONCLUSIONS: : Endoscopic light application with MB 0.5% concentration to the stomach may be regarded as a safe procedure despite some DNA injuries in the early period

Micro multi-nozzle jet coating of organic thin film for organic light-emitting diode lighting devices

Abstract Uniform deposition across large areas of an organic layer is one of the challenges for the industrial application of solution-based organic light‐emitting diode (OLED). In this paper, we propose an organic thin film deposition method for OLED using a micro multi-nozzle jet coating process. The developed micro multi-nozzle jet head consists of eighteen nozzles (100μm diameter), a side suction line, inlets, and a nozzle protection outer hole. To demonstrate organic thin film deposition for OLED lighting device fabrication, a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) solution was used as a hole injection layer (HIL). Thickness uniformity of the PEDOT:PSS thin film was analyzed by regulating the jetting pressure. Through single-path coating of twelve successive stable column-jet flows, PEDOT:PSS organic film of 26mm width was coated on an ITO substrate at 1m/s head speed. The PEDOT:PSS thin film of 24.25 ± 1.55nm (CV = 6.39%) thickness was obtained by the proposed coating method. For the feasibility test, OLED lighting devices with emission areas of 20mm × 20mm and 70mm × 70mm were successfully fabricated using PEDOT:PSS films deposited by a micro multi-nozzle jet coating method

Image polaritons in boron nitride for extreme polariton confinement with low losses

Polaritons in two-dimensional materials provide extreme light confinement that is difficult to achieve with metal plasmonics. However, such tight confinement inevitably increases optical losses through various damping channels. Here we demonstrate that hyperbolic phonon polaritons in hexagonal boron nitride can overcome this fundamental trade-off. Among two observed polariton modes, featuring a symmetric and antisymmetric charge distribution, the latter exhibits lower optical losses and tighter polariton confinement. Far-field excitation and detection of this high-momenta mode becomes possible with our resonator design that can boost the coupling efficiency via virtual polariton modes with image charges that we dub image polaritons. Using these image polaritons, we experimentally observe a record-high effective index of up to 132 and quality factors as high as 501. Further, our phenomenological theory suggests an important role of hyperbolic surface scattering in the damping process of hyperbolic phonon polaritons