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We study the asymptotic behaviour of the powers of a composition operator on various Banach spaces of holomorphic functions on the disc, namely, standard weighted Bergman spaces (finite and infinite order), Bloch space, little Bloch space, Bloch-type space and Dirichlet space. Moreover, we give a complete characterization of those composition operators that are similar to an isometry on these various Banach spaces. We conclude by studying the asymptotic behaviour of semigroups of composition operators on these various Banach spaces.
We present a detailed, complete glacier inventory for Alaska and neighboring Canada using multi-sensor satellite data from 2000 to 2011. For each glacier, we derive outlines and 51 variables, including center-line lengths, outline types and debris cover. We find 86 723 km2 of glacier area (27 109 glaciers >0.025 km2), ∼12% of the global glacierized area outside ice sheets. Of this area 12.0% is drained by 39 marine-terminating glaciers (74 km of tidewater margin), and 19.3% by 148 lake- and river-terminating glaciers (420 km of lake-/river margin). The overall debris cover is 11%, with considerable differences among regions, ranging from 1.4% in the Kenai Mountains to 28% in the Central Alaska Range. Comparison of outlines from different sources on >2500 km2 of glacierized area yields a total area difference of ∼10%, emphasizing the difficulties in accurately delineating debris-covered glaciers. Assuming fully correlated (systematic) errors, uncertainties in area reach 6% for all Alaska glaciers, but further analysis is needed to explore adequate error correlation scales. Preliminary analysis of the glacier database yields a new set of well-constrained area/length scaling parameters and shows good agreement between our area–altitude distributions and previously established synthetic hypsometries. The new glacier database will be valuable to further explore relations between glacier variables and glacier behavior.
The Randolph Glacier Inventory (RGI) is a globally complete collection of digital outlines of glaciers, excluding the ice sheets, developed to meet the needs of the Fifth Assessment of the Intergovernmental Panel on Climate Change for estimates of past and future mass balance. The RGI was created with limited resources in a short period. Priority was given to completeness of coverage, but a limited, uniform set of attributes is attached to each of the ~198 000 glaciers in its latest version, 3.2. Satellite imagery from 1999–2010 provided most of the outlines. Their total extent is estimated as 726 800 ± 34 000 km2. The uncertainty, about ±5%, is derived from careful single-glacier and basin-scale uncertainty estimates and comparisons with inventories that were not sources for the RGI. The main contributors to uncertainty are probably misinterpretation of seasonal snow cover and debris cover. These errors appear not to be normally distributed, and quantifying them reliably is an unsolved problem. Combined with digital elevation models, the RGI glacier outlines yield hypsometries that can be combined with atmospheric data or model outputs for analysis of the impacts of climatic change on glaciers. The RGI has already proved its value in the generation of significantly improved aggregate estimates of glacier mass changes and total volume, and thus actual and potential contributions to sea-level rise.
The pineal hormone melatonin is able to shift the timing of circadian
rhythms, including the sleep–wake cycle, and to promote sleep. Melatonin
agonists with similar properties have therapeutic potential for the
treatment of circadian rhythm sleep disorders. Depression is specifically
targeted by agomelatine, which is also a serotonin-2C (5-HT2C)
OH(1720 MHz) and methanol masers are now recognized to be excellent probes of the interactions of supernova remnants with molecular clouds and tracers of massive star formation, respectively. To better understand the nature of star formation activity in the central region of the Galaxy, we have used these two classes of masers combined with the IRAC and MIPS data to study prominent sites of ongoing star formation in the nuclear disk. The nuclear disk is characterized by massive GMCs with elevated gas temperatures, compared to their dust temperatures. We note an association between methanol masers and a class of mid-infrared “green sources”. These highly embedded YSOs show enhanced 4.5μm emission due to excited molecular lines.
The distribution of methanol masers and supernova remnants suggest a low efficiency of star formation (with the exception of Sgr B2), which we believe is due to an enhanced flux of cosmic ray electrons impacting molecular clouds in the nuclear disk. We also highlight the importance of cosmic rays in their ability to heat molecular clouds, and thus increase the gas temperature.
The variation in the substrate temperature during ion beam assisted deposition (IBAD), which employs the use of energetic ions to bombard a growing film, has been shown to influence the quality of crystalline texture in MgO films. Determining the acceptable deviation from the optimum ion to molecule ratio for different substrate temperatures establishes the optimum MgO deposition conditions. For each fixed deposition temperature, a set of samples was produced by varying the ion assist beam current from sample to sample while keeping the deposition rate constant. In this way, the ion to molecule ratio was modified and the range of achieving well textured films was determined. The investigation of the MgO texture dependence on the substrate temperature reveals that the best in-plane alignment is obtained at ˜ 25°C. At this temperature, MgO films with in-plane orientation distribution as low as 3.7° full width at half maximum (FWHM) have been attained. MgO films deposited at temperatures higher than 100°C have broad in-plane alignment. Although, the deposition at the lowest temperature (-150°C) did not improve the in-plane texture, the acceptable deviation from the optimum ion to molecule ratio for achieving biaxially textured films was the largest. As a trend, the acceptable ion to molecule deviation decreases with increasing substrate temperature. This is especially important for continuous IBAD MgO depositions where less restrictive conditions are desired.
We have used a low temperature magnetic imaging system to determine current pathways in 5 cm long “good” and “bad” regions of a 1-cm-wide YBa2Cu3O7-δ coated conductor. The good and bad regions were identified with 4 point probe measurements taken at 1 cm intervals along the tape length. The current density map from the good region showed the expected edge peaked structure, similar to that seen in previous work on high quality test samples grown on single crystal substrates. The structure was also consistent with theoretical understanding of thin film superconductors where demagnetizing effects are strong. The maps from the bad region showed that the current was primarily confined to the right half of the sample. The left half carried only a small current that reached saturation quickly. Effectively halving the sample width quantitatively explains the critical current measured in that section. Spatially resolved x-ray analysis with 1 mm resolution was used to further characterize the bad section and suggested an abnormally large amount of a-axis YBCO present. This may be the result of non-uniform heating leading to a low deposition temperature in that area.
Let u be a bounded slowly oscillating mild solution of an inhomogeneous Cauchy problem, u̇ (t) = Au (t) + f (t), on R or R+, where A is a closed operator such that σap (A) ∩iR is countable, and the Carleman or Laplace transform of f has a continuous extension to an open subset of the imaginary axis with countable complement. It is shown that u is (asymptotically) almost periodic if u is totally ergodic (or if X does not contain c0 in the case of a problem on R). Similar results hold for second-order Cauchy problems and Volterra equations.
The Montserrat Oriole Icterus oberi is endemic to the Caribbean island of Montserrat where, prior to 1995, it was widely distributed across the island's three main interior mountain ranges: the Centre, Soufriere and South Soufriere Hills. In July 1995, a long-dormant volcano on Chances Peak in the Soufriere Hills began to erupt. Since then the forest habitat of the oriole on the Soufriere and South Soufriere Hills has been devastated by pyroclastic flows and surges, heavy ash eruptions and rock falls. The Montserrat Oriole populations that inhabited these two mountain ranges have probably been lost. In December 1997, a census of the remaining Centre Hills population was undertaken to assess its status in the face of the heavy ash fall that occurred earlier the same year. To do this, a systematic grid of 140 sample points was overlaid on an area of 1,437.5 n a encompassing the Centre Hills, and a 10-minute count of all bird species was undertaken at 137 of these points during an eight-day survey period. The distance from the point to each oriole detected was measured and records of all other species were allocated to one of five distance bands radiating out from the point. Distance sampling was used to model densities, and thus to estimate population sizes, of eight bird species in the study area. It was estimated that 4,000 (95% CIs 1,500–7,800) Montserrat Orioles remain in the Centre Hills and thus the world. Although the probability of pyroclastic flows and surges overrunning the Centre Hills is considered rerrtote, it is recommended that the Montserrat Oriole be classified as Globally Threatened (Endangered) under the revised IUCN threat categories because of its loss of breeding habitat since 1995.
We successfully deposited high quality biaxially oriented BaxSr1-xTiO3 thin films on polycrystalline yttrium iron garnet substrates using both the metal-organic chemical liquid deposition and pulsed laser deposition methods with biaxially oriented MgO and yttriumstabilized- zirconia buffer layers. The dielectric losses of the films range from 0.005 to 0.015 while 25% of dielectric constant change was observed with 40V bias voltage up to 10 MHz. Both the dissipation and dielectric constant of the films remained nearly constants over a wide temperature range. A dual-tuning microwave phase shifter using a BST film grown on an MgO buffered polycrystalline YIG substrate was fabricated. A significant phase shift was observed in a wide frequency range when an electric bias or a magnetic field was applied to the device.
Fission fragment damage was introduced into aligned sintered samples of various superconductors containing small additions of UO2 by irradiation with thermal neutrons. Samples of aligned, sintered YBa2Cu3Ox, powdered Bi2Sr2Ca1Cu2Oy, powdered Bi1.7Pb0.3Sr2Ca2Cu3Oz, and epitaxial films of YBa2Cu3Ox on (100)SrTiO3 were used. Magnetic hysteresis, with the critical state model, was used to evaluate changes in the intragranular critical current. In the case of the Bi1.7Pb0.3Sr2Ca2Cu3Oz powders an increase in intragranular Jc at 0.8 T of greater than 70 times was produced by the radiation. The epitaxial film showed no change in Jc on irradiation. This behavior upon irradiation is attributed to the pinning caused by damage produced by the fission products of uranium.
Ten patients with seasonal affective disorder received the following treatments for 5 days each: (a) artificial daylight (2500 lux) from 20.00 to 23.00 and from 07.00 to 10.00 hours; (b) red light (300 lux) from 20.00 to 23.00 and from 07.00 to 10.00 hours; (c) artificial daylight (2500 lux) from 22.00 to 23.00 and from 07.00 to 08.00 hours. The antidepressant effect of treatment (a) was superior to that of treatment (b), suggesting that the effect of light treatment in winter depression is more than that of a placebo. The antidepressant effect of treatment (a) was superior to that of treatment (c), although these two treatments equally suppressed plasma melatonin concentrations. Consequently, in these patients there is a dissociation between the effect of light treatment on melatonin and the reduction of depression ratings.
Thin-film GdBa2Cu3Ox superconductors with an onset Tc > 90 K have been produced. The films were fabricated by thermal reaction in an oxidizing atmosphere of electron-beam deposited Ba/Gd/Cu multilayers. Attempts to produce the superconducting phase YBa2Cu3Ox by multilayer reaction were unsuccessful due to a positive heat of mixing between Y and Ba. The appearance of a wide superconducting transition in GdBa2Cu3Ox films may be the result of tunneling through a nonsuperconducting second phase.
Sintered compacts of magnetically aligned single-crystal particles have been studied by x-ray, microscopy, and magnetic measurements. Though significant alignment and very anisotropie magnetic hysteresis were obtained, the magnitude of the hysteresis indicates, through the critical state model, that the bulk critical current density remains low.
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