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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

The isolation, purification and properties of a nuclease from neurospora crassa conidia specific for single-stranded DNA

Rabin, E. Z. January 1971 (has links)
Note:
12

Spectroscopic studies of poly(vinyl fluoride)

Hong, Jin-Who January 1991 (has links)
No description available.
13

A Multi-Step Resonant Ionization Spectroscopy Technique Using CW Laser Excitation

Liu, Chen January 1988 (has links)
Note:
14

EVIDENCE FOR THE DIRECT DETECTION OF THE THERMAL SPECTRUM OF THE NON-TRANSITING HOT GAS GIANT HD 88133 b

Piskorz, Danielle, Benneke, Björn, Crockett, Nathan R., Lockwood, Alexandra C., Blake, Geoffrey A., Barman, Travis S., Bender, Chad F., Bryan, Marta L., Carr, John S., Fischer, Debra A., Howard, Andrew W., Isaacson, Howard, Johnson, John A. 23 November 2016 (has links)
We target the thermal emission spectrum of the non-transiting gas giant HD 88133 b with high-resolution near-infrared spectroscopy, by treating the planet and its host star as a spectroscopic binary. For sufficiently deep summed flux observations of the star and planet across multiple epochs, it is possible to resolve the signal of the hot gas giant's atmosphere compared to the brighter stellar spectrum, at a level consistent with the aggregate shot noise of the full data set. To do this, we first perform a principal component analysis to remove the contribution of the Earth's atmosphere to the observed spectra. Then, we use a cross-correlation analysis to tease out the spectra of the host star and HD 88133 b to determine its orbit and identify key sources of atmospheric opacity. In total, six epochs of Keck NIRSPEC L-band observations and three epochs of Keck NIRSPEC K-band observations of the HD 88133 system were obtained. Based on an analysis of the maximum likelihood curves calculated from the multi-epoch cross-correlation of the full data set with two atmospheric models, we report the direct detection of the emission spectrum of the non-transiting exoplanet HD 88133 b and measure a radial projection of the Keplerian orbital velocity of 40 +/- 15 km s(-1), a true mass of 1.02(-0.28)(+0.61) M-J, a nearly face-on orbital inclination of 15(-5)(+60), and an atmosphere opacity structure at high dispersion dominated by water vapor. This, combined with 11 years of radial velocity measurements of the system, provides the most up-to-date ephemeris for HD 88133.
15

HI4PI: a full-sky H i survey based on EBHIS and GASS

Ben Bekhti, N., Flöer, L., Keller, R., Kerp, J., Lenz, D., Winkel, B., Bailin, J., Calabretta, M. R., Dedes, L., Ford, H. A., Gibson, B. K., Haud, U., Janowiecki, S., Kalberla, P. M. W., Lockman, F. J., McClure-Griffiths, N. M., Murphy, T., Nakanishi, H., Pisano, D. J., Staveley-Smith, L. 20 October 2016 (has links)
Context. Measurement of the Galactic neutral atomic hydrogen (H I) column density, NH I, and brightness temperatures, T-B, is of high scientific value for a broad range of astrophysical disciplines. In the past two decades, one of the most-used legacy H I datasets has been the Leiden/Argentine/Bonn Survey (LAB). Aims. We release the H I 4 pi survey (HI4PI), an all-sky database of Galactic H I, which supersedes the LAB survey. Methods. The HI4PI survey is based on data from the recently completed first coverage of the Effelsberg-Bonn H I Survey (EBHIS) and from the third revision of the Galactic All-Sky Survey (GASS). EBHIS and GASS share similar angular resolution and match well in sensitivity. Combined, they are ideally suited to be a successor to LAB. Results. The new HI4PI survey outperforms the LAB in angular resolution (theta(FWHM) = 16'.2) and sensitivity (sigma(rms) = 43 mK). Moreover, it has full spatial sampling and thus overcomes a major drawback of LAB, which severely undersamples the sky. We publish all-sky column density maps of the neutral atomic hydrogen in the Milky Way, along with full spectroscopic data, in several map projections including HEALPix.
16

The study on Photoreflectance Of ZnSe

Ko, Yi-Ling 23 June 2001 (has links)
We have studies the II-VI ternary compound semiconductor ZnSe grown by molecular beam epitaxy ¡]MBE¡^Method. The modulation spectroscopy was used to study ZnSe. ZnSe epilayer was grown on GaAs substrate. The lattice mismatch¡]0.27 ¢H¡^between GaAs and ZnSe create a strain at the GaAs/ZnSe interface. The strain will remove the degeneracy of heavy and light holes to conduction band transition energies. We use the photoreflectance to measure the energy of different thickness ZnSe epilayers at low temperature. It was found that as the epilayer thickness becomes larger, the£GE will become smaller. We have also analyzed the energy of different temperatures in terms of Varshni relation, and the temperature dependence of the broadening parameters.
17

Implementation of Wavelet Encoding Spectroscopic Imaging Technique on a 3 Tesla Whole Body MR Scanner

Fu, Yao 12 April 2010 (has links)
A 3D wavelet based encoding spectroscopic method (WE-SI) is investigated and implemented on a 3 Tesla Siemens Scanner. Compared to CSI, the proposed method is able to reduce acquisition time, and preserves the spatial metabolite distribution. As expected, a decrease in Signal to Noise Ratio (SNR) is noticed in WE-SI data compared to CSI. The dissertation explores important physical principles in MRI and spectroscopic imaging as a background, following by introduction of the wavelet encoding theory and comparison to Fourier encoding.
18

Implementation of Wavelet Encoding Spectroscopic Imaging Technique on a 3 Tesla Whole Body MR Scanner

Fu, Yao 12 April 2010 (has links)
A 3D wavelet based encoding spectroscopic method (WE-SI) is investigated and implemented on a 3 Tesla Siemens Scanner. Compared to CSI, the proposed method is able to reduce acquisition time, and preserves the spatial metabolite distribution. As expected, a decrease in Signal to Noise Ratio (SNR) is noticed in WE-SI data compared to CSI. The dissertation explores important physical principles in MRI and spectroscopic imaging as a background, following by introduction of the wavelet encoding theory and comparison to Fourier encoding.
19

Near infrared quantitative chemical imaging as an objective, analytical tool for optimization of the industrial processing of wheat

Boatwright, Mark Daniel January 1900 (has links)
Doctor of Philosophy / Biochemistry and Molecular Biophysics Interdepartmental Program / John M. Tomich / David L. Wetzel / The technique of near infrared chemical imaging has been widely used for many industrial applications. It offers selectivity and/or sensitivity for numerous organic functional groups. The advantage of the near infrared spectroscopic region is the linear relationship of absorbance and concentration that enables quantitation. This universally employed technique has been a boon for research studies in the industrial process of wheat milling for the production of flour. The milling process has numerous sequential grinding and sieving steps that enable selective physical segregation of a starch rich endosperm product from wheat. Thousands of spectra of purified endosperm and non-endosperm standards are collected to develop a spectral library. Quantitation of the purity of individual processing streams is accomplished by applying a partial least squares calibration that is based upon the spectral library. The quantitative chemical imaging technique is useful for determination of endosperm purity profiles for mill flour streams. These plots reveal purity changes as less pure streams are added to produce a flour blend. The chemical structural basis furthermore allows comparison of purity even with changes in the wheat blend being milled with representative standardization. Furthermore, whereas a certain section of sieves is responsible, for designating the material defined as flour, application of the spectroscopic method is obvious. Select examples of key processing streams were studied to show the possibility of sieve-by-sieve analysis of the physical separation to provide mill optimization. These novel methods of analysis would not be possible without the sensitive and selective method of quantitative chemical imaging. Application of this technique to a few select unit processes is projected to reasonably affect a 1% increase in the yield of high quality flour. This amounts to a significant financial gain against low profit margins.
20

FIGS—Faint Infrared Grism Survey: Description and Data Reduction

Pirzkal, Norbert, Malhotra, Sangeeta, Ryan, Russell E., Rothberg, Barry, Grogin, Norman, Finkelstein, Steven L., Koekemoer, Anton M., Rhoads, James, Larson, Rebecca L., Christensen, Lise, Cimatti, Andrea, Ferreras, Ignacio, Gardner, Jonathan P., Gronwall, Caryl, Hathi, Nimish P., Hibon, Pascale, Joshi, Bhavin, Kuntschner, Harald, Meurer, Gerhardt R., O’Connell, Robert W., Oestlin, Goeran, Pasquali, Anna, Pharo, John, Straughn, Amber N., Walsh, Jeremy R., Watson, Darach, Windhorst, Rogier A., Zakamska, Nadia L, Zirm, Andrew 01 September 2017 (has links)
The Faint Infrared Grism Survey (FIGS) is a deep Hubble Space Telescope (HST) WFC3/IR (Wide Field Camera 3 Infrared) slitless spectroscopic survey of four deep fields. Two fields are located in the Great Observatories Origins Deep Survey-North (GOODS-N) area and two fields are located in the Great Observatories Origins Deep Survey-South (GOODS-S) area. One of the southern fields selected is the Hubble Ultra Deep Field. Each of these four fields were observed using the WFC3/G102 grism (0.8 mu m-1.15 mu m continuous coverage) with a total exposure time of 40 orbits (approximate to 100 kilo-seconds) per field. This reaches a 3 sigma continuum depth of approximate to 26 AB magnitudes and probes emission lines to similar to 10(-17) erg s(-1) cm(-2). This paper details the four FIGS fields and the overall observational strategy of the project. A detailed description of the Simulation Based Extraction (SBE) method used to extract and combine over 10,000 spectra of over 2000 distinct sources brighter than m(F105W) = 26.5 mag is provided. High fidelity simulations of the observations is shown to significantly improve the background subtraction process, the spectral contamination estimates, and the final flux calibration. This allows for the combination of multiple spectra to produce a final high quality, deep, 1D spectra for each object in the survey.

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