12 research outputs found
Low energy excitations in crystalline perovskite oxides: Evidence from noise experiments
In this paper we report measurements of 1/f noise in a crystalline metallic
oxide with perovskite structure down to 4.2K. The results show existence of
localized excitations with average activation energy 70-80 meV which
produce peak in the noise at T 35-40K. In addition, it shows clear
evidence of tunnelling type two-level-systems (as in glasses) which show up in
noise measurements below 30K.Comment: 11 pages, 4 figures, to appear in Phys Rev B, vol 58, 1st Dec issu
A comparison of aqueous extracts from the B horizon of a birch and aspen forest in interior Alaska
Effects of carbon, fertilizer, and drought on foliar chemistry of tree species in interior Alaska
Changes in foliarchemistryresultingfromchanges in forest-flooarnd min- eral-soilmoistureavailability,forest-floomricrobialenergysupply,andnitrogenavailability wereinvestigatedacross thesuccessional sequences in bothuplandand floodplainlandscape positions.Three amendments,sugar,sawdust,and nitrogenfertilizer(NH4NO3),were ap- plied to a series of threeupland and fourfloodplainsuccessional sites. The sugar and sawdusttreatmentwseredesignedtoincreasethecarbon:nitrogenratio(C/N)oftheforest floorto values typicalof black spruce sites (C/N = 50). The nitrogenfertilizertreatment was designed to equal estimatedyearlyN mineralizationin an attempto double available nitrogenin the forestfloor.A moistureexclusion treatmentwas designed to remove all summerrainfallfromthe treatmenptlots.
Foliarphosphorusconcentrationwserehigherintheuplandsitesthanonthefloodplain. No consistentdifferenceswerereportedamongsuccessionalstageswithina landscapeunit. Theeffectofeithersugarorsawdusttreatmenwtastodecreasefoliarphosphorusconcen- trations.Sugar produced more significantdifferencesthan did sawdust. Sugar treatments decreased foliarnitrogenin all treespecies except forwhitespruce,while fertilizertended to increasefoliarnitrogenI.n thesecond yearfollowingtreatmentherewas notan increase in foliarnitrogenconcentrationresultingfromfertilizertreatment
Influence of phosphorus on growth and biomass distribution of Alaskan taiga tree seedlings
Partitioning of Cellulase and Phospho Mono Esterase Activities in Aspen and Birch Forest Soils
Vegetation Soils and Forest Productivity in Selected Forest Types in Interior Alaska USA
Rest-Frame Mid-Infrared Detection of an Extremely Luminous Lyman Break Galaxy with the Spitzer Infrared Spectrograph (IRS)
We present the first rest-frame of approximately 4 microns detection of a Lyman break galaxy. The data were obtained using the 16 microns imaging capability of the Spitzer Infrared Spectrograph. The target object, J134026.44+634433.2, is an extremely luminous Lyman break galaxy at z=2.79, first identified in Sloan Digital Sky Survey (SDSS) spectra (as reported by Bentz et al.). The source is strongly detected with a flux of 0.94 +/- 0.02 mJy. Combining Spitzer and SDSS photometry with supporting ground-based J- and K-band data, we show that the spectral energy distribution is consistent with an actively star-forming galaxy. We also detect other objects in the Spitzer field of view, including a very red mid-infrared source. We find no evidence of a strong lens among the mid-infrared sources
Probing Optimal Reaction Energy for Synthesis of Element 119 from <sup>51</sup>V+<sup>248</sup>Cm Reaction with Quasielastic Barrier Distribution Measurement
International audienceThe quasielastic barrier distribution of 51V+248Cm was extracted by measuring the excitation function of quasielastic backscattering using a gas-filled recoil ion separator, GARIS-III. The obtained barrier distribution is well explained by the coupled-channels calculation, indicating a significant effect of the rotational excitation of deformed 248Cm. From the measured average Coulomb barrier height and deformation parameters of 248Cm, the side-collision energy leading to a compact configuration of colliding nuclei was obtained. The relation between the side collision energy and the excitation function of the evaporation-residue cross sections in the 48Ca+248Cm system was evaluated as a reference for the 51V+248Cm case. The optimal reaction energy to synthesize a new element 119 at the 51V+248Cm fusion reaction (3n and 4n channels) was estimated with an aid of these experimental data