A new experimental technique has been developed for the determination of absorption line profiles in steady-state plasmas. The method involves observing the total transmitted line intensity of one component of the longitudinal Zeeman pattern from a background source. The frequency shift of this line is determined from the known magnetic field and the Landé g-factors involved. The light from the background source is amplitude modulated by a chopping wheel, and the intensity of the transmitted light is measured with a phase-sensitive detector. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Photoelectron spectroscopy is the study of the kinetic energies of the photoelectrons ejected from gaseous species by monochromatic radiation. Subtraction of these kinetic energies from the incident photon energy yields the binding energies of the orbitals from which the electrons were removed. The work to be described falls into two main parts. The first is concerned with the development of a new type of spectrometer to measure such kinetic energies. To date, all photoelectron spectrometers designed specifically for gaseous samples have employed a retarding field of cylindrical geometry to energy-analyze the emitted photoelectrons. Consideration of the angular distribution with which electrons are ejected during the photoionization process indicates that a spectrometer utilizing a retarding field of spherical geometry should give a stopping curve, the first differential of which is close to the true photoelectron kinetic energy spectrum. Instruments of both cylindrical and spherical geometry were constructed and their properties tested. Conclusive evidence for the superiority of the spherical system is presented together with details of its construction and operation. The second part of this thesis/contains the results of photoelectron spectroscopic studies on twenty-one atoms and molecules (Ar, Kr, Xe, H₂, HD, D₂, N₂, CO, O₂, NO, HF, HCl , HBr, HI, F₂, Cl₂, Br₂, I₂,N₂O, NO₂ and NH₃). The energies of the ionic states could be obtained to a precision of 0.01 ev., and they agree, well with available spectroscopic data. In many instances new ionic states are found, and where possible they are correlated with states predicted by molecular orbital theory. Relative transition probabilities to the various ionic states are also obtained by this method. They are, in nearly every case, the only experimental values available. The spacings and relative probabilities for formation of ionic vibrational levels have been measured for certain states in H₂, HD, D₂, N₂, CO, O₂, NO, F₂, N₂O and NO₂ and the values obtained compared with spectroscopic and calculated data where this is available. / Science, Faculty of / Chemistry, Department of / Graduate

A study involving both the applications of internuclear double resonance (INDOR) spectroscopy and the synthesis of carbohydrates containing organometallic substrates was undertaken. The thesis is divided into two sections to facilitate discussion. The first section involves an evaluation of homonuclear and heteronuclear INDOR as a tool for spectral analysis. Homonuclear INDOR studies of carbohydrate derivatives such as 2-deoxy-a-D-arabino-hexo-pyranose(l), sucrose octaacetate(2) and D-ribose(3) have shown this technique to be extremely effective for analysing multi-line spectra having hidden transitions. Within certain power-level ranges, the resolution of the INDOR responses is comparable to that of the normal proton spectra. Heteronuclear INDOR spectra were obtained indirectly by monitoring specific transitions in the proton spectra while irradiating the appropriate heteronuclear frequency. In this manner, the methoxy-methyl ¹³C INDOR shift of a number of anomeric gluco- and xylo-pyranoside derivatives were measured. The ¹³C shifts of the α anomers were found to be ca. 2 ppm to high field of the β anomer. This difference is more diagnostic than the small 0.1 ppm variation between two methoxy-methyl anomers in the ¹H n.m.r. spectra. Such diagnostic differences were not found for the acetoxy-methyl ¹³C shifts of anomeric sugar acetate derivatives. Other heteronuclear INDOR spectra were readily obtained for organo-metallic compounds such as trimethylphosphite(15), trimethyltin chloride (16), bromosilane(17) and tetramethyl lead(18). The second section of the thesis deals with the synthesis of some phosphorus and organometallic derivatives of monosaccharides. Treatment of various primary O-tosyl sugar derivatives with lithium diphenyl-phosphine reagent ,19, gave, in ca. 70% yields, such products as diphenyl {1,2 :3,5-di-0-methylene-α-D-glucofuranose} 6-C-phosphine oxide(20b), diphenyl {methyl 2,3,4-tri-0-acetyl-α-D-glucopyranoside} 6-C-phosphine oxide(21b) and diphenyl {l,2:3,4-di-0-isopropylidene-α-D-galactopyranose} 6-C-phosphine oxide(22b). The facile preparation of 22b is rather unique because of the known resistance of the O-tosyl group of the sugar reactant toward nucleophilic displacement. Diphenyl {3,6-anhydro-l,2-0-isopropylidene-α-L-idofuranose} 5-C-phosphine oxide(24b) was obtained in 31% yield via nucleophilic displacement of the corresponding 5-0-mesyl derivative using 19_. This typified the much lower yields obtained from secondary sulphonyl displacements. Other secondary sugar diphenyl-phosphine oxide derivatives were prepared in 50-70% yields from the opening of sugar epoxides with 19_. Notably, the scission of the epoxide bond of methyl 2,3-anhydro-3-L-ribopyranoside(29) gave diphenyl ^methyl 2,4-0-acetyl-B-L-xylopyranosidej. 3-C-phosphine oxide(30). The product was found to favour the conformation in which all the major substituents are axial. The ³¹P chemical shifts for all the sugar diphenylphosphine oxide , derivatives were measured using the INDOR technique. These shifts provided confirmation that the products were phosphine oxides. It was further shown by use of ³¹P decoupling that ³JpH ranges of 6.6-11.8 Hz and 22-33 Hz for 60° and 180° dihedral angles respectively, were present in these products. These couplings are similar to those reported for, vicinal P-H couplings in hydroxy phosphonate derivatives. Preliminary experiments, undertaken to evaluate the effectiveness of other organometallics such as lithium triphenyltin(33), lithium tri-phenyllead(34) and lithium triphenylsilane (35) , showed 33 to be an effective reagent for displacing primary O-tosylates and opening epoxides of sugar derivatives. Both 34 and 35 gave poor yields when used to displace the 0-tosylate group of 20b. Generally, organometallic species were shown to provide a viable means of synthesizing novel sugar derivatives. / Science, Faculty of / Chemistry, Department of / Graduate

<pre>The Average Transform Smooth (ATS) statistical methods [McRae, Mallows, and Cleveland], are applied to measurements of a non-gaussian random variable to make them close to gaussian. This gaussianization makes use of the well known concept of variance stabilizing transformation, but takes it further by first averaging blocks of r measurements, transforming next, and then smoothing. The smoothing can be nonparametric, or can be the fitting of a parametric model. The gaussianization makes analysis simpler and more effective.</pre><pre><br></pre><pre>In this work ATS is applied to the periodogram of a stationary parametric time series, and makes use of the periodogram large sample properties given the true power spectrum [Brillinger], to develop a new approach to parametric time series model estimation and model diagnostics. The ATS results and the theory are reformulated as a regression model, PPS-REG, involving true power spectrum and the periodogram. PPS-REG has attractive properties: iid gaussian error terms with mean 0 and a known variance; accurate estimation; much faster estimation than the classical maximum likelihood when the time series is large; enables the use of the very powerful classical regression model diagnostics; bases the diagnostics on the power spectrum, adding substantially to the standard use of the autocovariance function for diagnosing the fits of models specified in the time domain.</pre>

The high prevalence of autism spectrum disorder (ASD) results in large costs to individuals, families, and society. Among diagnosed individuals, restrictive and repetitive behaviors (RRBs) correlate with functional impairments substantially impacting wellbeing but remain less studied than social and communication deficits. Brain resting-state functional connectivity (fc) measures intrinsic, potentially RRB-associated neural dynamics. Here, whole-brain (WB), and iterated seed-based (SB)fc guided by the preceding WBfc and a priori hypotheses was performed. Combined results were used to model a brain network beginning with qualitative assessment of its potential functional association with RRBs. Once rigorously defined, the network was used to inform construction of a dynamical systems model of brain activity hypothesized to correlate with RRB severity. Qualitative model behavior tracked expectations of real cortical activity in RRB presentation. Model numerical output was found to correlate with behavioral measures of RRBs to a significantly greater degree than the underlying brain connectivity values themselves did. Some summary measures of model output were also found to correlate significantly, though near threshold, with severity measures in the other two ASD core deficit domains, and particularly, far more extensively than should be expected given the underlying brain connectivity values themselves were apparently effectively wholly uncorrelated with the measures. Significant findings are: (1) dynamical modeling of brain activity can identify significant correlations with symptom manifestation that fc alone cannot; (2) dynamical modeling of brain activity could potentially increase understanding of ASD’s extensive heterogeneity across symptom domains; (3) extensive overlap between the constructed network and known RRB-implicated brain divisions was identified, with cerebellum, increasingly implicated in distributed neocortical functional differences in RRBs in humans and animal models, centrally connected to multiple such divisions; (4) further overlap is found via striatal circuitry, implicated in multiple RRB-like behaviors previously, and forming at least 1/3 of the functional basis for the network’s hypothetical relationship with RRBs; (5) ASD-associated angular gyrus, PFC, ACC overlap was found. This successful tandem application of fc, dynamical modeling, and neurocognitive network theory illustrates the need for broad theoretical approaches in illuminating ASD heterogeneity and the neurocognitive underpinnings of specific ASD presentations. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

The Interactive Video Data Service (IVDS) system allows consumers to browse the Internet, request information on products or services, make purchases, indicate preferences, and perform other interactive applications. To provide this service, the IVDS system has three subsystems: Consumer Control (CC), Cell Repeater (CR), and Host subsystem. In the CC subsystem, an IVDS transceiver box is placed near a television set. Once the consumer sends a command to the transceiver box using a standard television/VCR/Cable remote control, the transceiver box receives information embedded in the television audio, and then transmits the information to the CR subsystem as a radio frequency (RF) spread spectrum message. The CR subsystem decodes the spread spectrum message and forwards it to the Host subsystem for processing. Located in the CR subsystem, a custom designed circuit board, called the decoder board, uses surface mounted components to decode and packetize the spread spectrum message for transfer to the CR main processor. This paper provides a functional description of the hardware components on the decoder board, and describes the hardware/software developed for interfacing the decoder board to the radio receiver and to the CR main processor. Hardware modifications were needed to correct timing problems between components. Software was developed to initialize the components for downconverting, despreading, and demodulating spread spectrum messages, and to packetize them for transfer to the CR main processor. This paper also discusses the tests used to verify both the performance of the decoder board software and the operation of the hardware components. / Master of Science

A dissertation submitted to the Faculty of Science, School of Chemistry, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, 2017. / Pyridyl-imine ligands L1-L4 were prepared by condensation of pyridine-2-carboxyaldehyde with an appropriate amine. Characterization by NMR spectroscopy, infrared spectroscopy, mass spectrometry and elemental analysis confirmed successful preparation in yields of 64-88%. These ligands were used to prepare Pd(II) complexes C1-C4, from PdCl2(CH3CN)2 and the corresponding pyridyl-imine ligand. 1H-NMR, 13C-NMR, FT-IR, mass spectrometry and elemental analysis confirmed coordination. Attempts to prepare target Fe(II) complexes C5-C8 by reacting the ligands with anhydrous FeCl2 were unsuccessful. Infrared data suggested coordination of ligands to the Fe centre, however mass spectrometry and elemental analysis data revealed that target complexes were not obtained. Pd(II) complexes C1-C4 were evaluated as catalyst precursors for 1-hexene oligomerization and norbornene polymerization using methylaluminoxane (MAO) as co-catalyst. The oligomerization of 1-hexene was investigated in a neat reaction media at various Al:Pd ratios. All investigated complexes were found to be inactive for the oligomerization of 1-hexene. From 1H-NMR spectroscopy and GC-MS analysis it was observed that the product distribution was mainly a mixture of 2-hexene and 3-hexene isomers. Parameters such as temperature and time did not have any significant influence towards the productivity of 1-hexene oligomers. Norbornene polymerization studies were carried out with Pd(II) complex C4 in toluene at room temperature. This complex was found to exhibit good activity for norbornene polymerization, producing a vinyl bicyclic polymer, confirmed with infrared and solid state 13C-NMR spectroscopy. Increasing the amount of co-catalyst (MAO) and temperature did not have any significant influence on the activity and monomer conversion. However, increasing reaction time was observed to have a significant influence on the activity. / MT2017

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