84 research outputs found
Application of fast Fourier transforms to EPR spectra of free radicals in solution
A method of reducing EPR spectra of free radicals in solution is presented in detail. This method is based on the use of the fast Fourier transform algorithm and curve fitting in the Fourier space by weighted least-squares minimization. Comparison with previous work is shown for EPR spectra of methyl viologen.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23183/1/0000110.pd
Pottery production and trade in the Banda zone, Indonesia: the Kei tradition in its spatial and historical context
This paper provides the first comprehensive description of pottery production in the Kei islands of eastern Indonesia, based on field data collected mainly in 1981 and on Museum collections in the UK and The Netherlands. The account is situated in what we know of the dynamics of trading systems that existed in the Moluccan islands between 1500 and 2000. Kei pottery is widely thought to be the successor of a tradition established in the Banda islands that was extinguished with the 1621 Dutch massacre of Bandanese, but re-established at several sites in the Kei islands by Bandanese migrants after this date. These claims are critically examined using ethnographic and archaeological data, and an attempt made to compare the production and trading patterns of pottery in the ‘Banda zone’ before and after 1621
The Use of Auxlliaries in Performing Medical Surgical Procedures and Sorting Patients in the O.P.D
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Diatoms as indicators of historical water quality: a comparison of samples taken in the Wemmershoek catchment (Western Province, South Africa) in 1960 and 2008
Historical diatom records provide a means of retrospectively determining water quality and inferring ecological condition in rivers and streams. In this study we re-sampled sites originally sampled 48 years previously. We then determined the scores for the Biological Diatom Index (BDI) and the South African Diatom Index (SADI) for each dataset. The results revealed that the present day conditions in this relatively undisturbed locality were almost identical to those reflected by the samples collected half a century before. This illustrates the value of historical diatom data for the purposes of determining antecedent water quality
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Integration of finite element analysis and numerical optimization techniques for RAM transport package design
Type B radioactive material transport packages must meet strict Nuclear Regulatory Commission (NRC) regulations specified in 10 CFR 71. Type B containers include impact limiters, radiation or thermal shielding layers, and one or more containment vessels. In the past, each component was typically designed separately based on its driving constraint and the expertise of the designer. The components were subsequently assembled and the design modified iteratively until all of the design criteria were met. This approach neglects the fact that components may serve secondary purposes as well as primary ones. For example, an impact limiter`s primary purpose is to act as an energy absorber and protect the contents of the package, but can also act as a heat dissipater or insulator. Designing the component to maximize its performance with respect to both objectives can be accomplished using numerical optimization techniques
Added precision in 57Fe Mossbauer spectroscopy
This paper contains (1) the necessary mathematics for a precise interpretation of Mossbauer data, and (2) a characterization of a spectrometer designed specifically to maximize the information avalable from these data. The innovative aspects of this spectrometer are that it provides a known absorber lineshape, that it is quantitative, and that is provides information of the vibrational states of the absorber via the second order Doppler shift vs temperature and the total absorption vs temperature. The spectrometer allows sample temperature and applied magnetic field to be varied in any combination of 2-350 K or 0-6 T, respectively. Simultaneous collection of four data streams allows an accurate representation of the transmission spectrum. Sophisticated computer treatment with extensive use of least squares fitting procedures and fast Fourier transform techniques provides the final output display of sample cross-section vs standardized source velocity. The cross-section display is shown to be independent of the thickness of samples with Mossbauer optical densities up to 3. In addition, we report the method and results of measurements which must precede the operation of the spectrometer: (1) the absorption coefficient of iron at 14 keV: (498+/-7)cm-1, (2) the Debye temperature of our source (57Co in rhodium matrix): (361+/-20)K, (3) the source lineshape: three Lorentzians with Heisenberg linewidth, a center line with twice the intensity of the symmetrically placed outer lines which are spaced 0.055 mm/s apart, (4) the Mossbauer effect cross-section for 57Fe: (2.4+/-0.2) x 10-18 cm2, (5) the Debye temperature of iron (NBS # 1541): (430+/-30) K, and (6) the values for the Hamiltonian parameters of iron metal (NBS # 1541) at 290, 101 and 4.2 K. The precision of the determined Hamiltonian parameters is defined in terms of a statistic with a weighted [chi]2 distribution.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22843/1/0000403.pd
The Molecular and Submolecular Structure of the Semiquinone Cations of Alloxazines and Isoalloxazines as Revealed by Electron Spin Resonance Spectroscopy
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