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31.
Andrew O. Finley Abhirup Datta Bruce D. Cook Douglas C. Morton Hans E. Andersen 《Journal of computational and graphical statistics》2019,28(2):401-414
We consider alternate formulations of recently proposed hierarchical nearest neighbor Gaussian process (NNGP) models for improved convergence, faster computing time, and more robust and reproducible Bayesian inference. Algorithms are defined that improve CPU memory management and exploit existing high-performance numerical linear algebra libraries. Computational and inferential benefits are assessed for alternate NNGP specifications using simulated datasets and remotely sensed light detection and ranging data collected over the U.S. Forest Service Tanana Inventory Unit (TIU) in a remote portion of Interior Alaska. The resulting data product is the first statistically robust map of forest canopy for the TIU. Supplemental materials for this article are available online. 相似文献
32.
Krenner HJ Clark EC Nakaoka T Bichler M Scheurer C Abstreiter G Finley JJ 《Physical review letters》2006,97(7):076403
We optically probe and electrically control a single artificial molecule containing a well defined number of electrons. Charge and spin dependent interdot quantum couplings are probed optically by adding a single electron-hole pair and detecting the emission from negatively charged exciton states. Coulomb- and Pauli-blockade effects are directly observed, and tunnel coupling and electrostatic charging energies are independently measured. The interdot quantum coupling is shown to be mediated by electron tunneling. Our results are in excellent accord with calculations that provide a complete picture of negative excitons and few-electron states in quantum dot molecules. 相似文献
33.
Abbasi RU Abu-Zayyad T Allen M Amman JF Archbold G Belov K Belz JW Ben Zvi SY Bergman DR Blake SA Brusova OA Burt GW Cannon C Cao Z Connolly BC Deng W Fedorova Y Finley CB Gray RC Hanlon WF Hoffman CM Holzscheiter MH Hughes G Hüntemeyer P Jones BF Jui CC Kim K Kirn MA Loh EC Maestas MM Manago N Marek LJ Martens K Matthews JA Matthews JN Moore SA O'Neill A Painter CA Perera L Reil K Riehle R Roberts M Rodriguez D Sasaki N Schnetzer SR Scott LM Sinnis G Smith JD Sokolsky P Song C Springer RW 《Physical review letters》2008,100(10):101101
The High Resolution Fly's Eye (HiRes) experiment has observed the Greisen-Zatsepin-Kuzmin suppression (called the GZK cutoff) with a statistical significance of five standard deviations. HiRes' measurement of the flux of ultrahigh energy cosmic rays shows a sharp suppression at an energy of 6 x 10(19) eV, consistent with the expected cutoff energy. We observe the ankle of the cosmic-ray energy spectrum as well, at an energy of 4 x 10(18) eV. We describe the experiment, data collection, and analysis and estimate the systematic uncertainties. The results are presented and the calculation of the statistical significance of our observation is described. 相似文献
34.
Aromatic substitutions on 4-phenylisothiazole by nitric acid, halogens, chlorosulfonic acid and acetic anhydride take place under relatively mild conditions to give predominantly para and ortho substitution on the benzene ring. By contrast, the 3-isothiazolyl group has been shown to be meta directing. Several derivatives of 4-phenylisothiazole are described. 相似文献
35.
Fry PW Itskevich IE Mowbray DJ Skolnick MS Finley JJ Barker JA O'Reilly EP Wilson LR Larkin IA Maksym PA Hopkinson M Al-Khafaji M David JP Cullis AG Hill G Clark JC 《Physical review letters》2000,84(4):733-736
New information on the electron-hole wave functions in InAs-GaAs self-assembled quantum dots is deduced from Stark effect spectroscopy. Most unexpectedly it is shown that the hole is localized towards the top of the dot, above the electron, an alignment that is inverted relative to the predictions of all recent calculations. We are able to obtain new information on the structure and composition of buried quantum dots from modeling of the data. We also demonstrate that the excited state transitions arise from lateral quantization and that tuning through the inhomogeneous distribution of dot energies can be achieved by variation of electric field. 相似文献
36.
Holder PG Finley DT Stephanopoulos N Walton R Clark DS Francis MB 《Langmuir : the ACS journal of surfaces and colloids》2010,26(22):17383-17388
We have developed a method for integrating the self-assembling tobacco mosaic virus capsid into hydrophobic solvents and hydrophobic polymers. The capsid was modified at tyrosine residues to display an array of linear poly(ethylene glycol) chains, allowing it to be transferred into chloroform. In a subsequent step, the capsids could be transferred to a variety of hydrophobic solvents, including benzyl alcohol, o-dichlorobenzene, and diglyme. The thermal stability of the material against denaturation increased from 70 °C in water to at least 160 °C in hydrophobic solvents. With a view toward material fabrication, the polymer-coated TMV rods were also incorporated into solid polystyrene and thermally cast at 110 °C. Overall, this process significantly expands the range of processing conditions for TMV-based materials, with the goal of incorporating these templated nanoscale systems into conductive polymer matrices. 相似文献
37.
F. J. R. Schülein J. Pustiowski K. Müller M. Bichler G. Koblmüller J. J. Finley A. Wixforth H. J. Krenner 《JETP Letters》2012,95(11):575-580
We experimentally study the optical emission of a thin quantum well and its dynamic modulation by a surface acoustic wave (SAW). We observe a characteristic transition of the modulation from one maximum to two maxima per SAW cycle as the acoustic power is increased which we find in good agreement with numerical calculations of the SAW controlled carrier dynamics. At low acoustic powers the carrier mobilities limit electron-hole pair dissociation, whereas at high power levels the induced electric fields give rise to efficient acousto-electric carrier transport. The direct comparison between the experimental data and the numerical simulations provide an absolute calibration of the local SAW phase. 相似文献
38.
P. Given E. Wheeler G. Noll J. Finley 《Journal of Dispersion Science and Technology》2013,34(4-5):505-530
Confectionery coatings employ hard butter fat systems made from both lauric and non-lauric source oils. These oils are routinely modified by a combination of treatments including hydrogenation, fractionation and interesterification to achieve desired physical properties. Such processing methods create heterogeneous triglyceride mixtures consisting of a variety of compositional and positional isomers. Published phase diagrams of “simple” binary triglyceride mixtures of closely related molecules are complex, and suggest that innumberable unique liquid and solid phases may co-exist at any given temperature ( and pressure ) in vastly more complex triglyceride mixtures such as confectionery hard butters. Thus we may view confectionery fat systems as multiphasic mixtures (liquid, solid and compositional) with a propensity to undergo liquid content fluctuations and crystal size/morphology changes in response to slight changes in temperature. A true equilibrium among all phases may indeed never be attained, and a potential for movement of certain components in response to temperature change is probably constant. Surface growth of long needle-like fat crystals, “fat bloom”, most likely results from this non-equilibrium condition and serves to reduce the system's free energy. The ever present, ever changing liquid phase(s) is viewed as the vehicle for free energy minimization via triglyceride migration and ongoing crystal growth. 相似文献
39.
40.
D. Schuh J. Bauer E. Uccelli R. Schulz A. Kress F. Hofbauer J.J. Finley G. Abstreiter 《Physica E: Low-dimensional Systems and Nanostructures》2005,26(1-4):72
We report on a new approach for positioning of self-assembled InAs quantum dots on (1 1 0) GaAs with nanometer precision. By combining self-assembly of quantum dots with molecular beam epitaxy on in situ cleaved surfaces (cleaved-edge overgrowth) we have successfully fabricated arrays of long-range ordered InAs quantum dots. Both atomic force microscopy and micro-photoluminescence measurements demonstrate the ability to control position and ordering of the quantum dots with epitaxial precision as well as size and size homogeneity. Furthermore, photoluminescence investigations on dot ensembles and on single dots confirm the high homogeneity and the excellent optical quality of the quantum dots fabricated. 相似文献