High-resolution hyperfine spectroscopy of excited states using electromagnetically-induced transparency

We use the phenomenon of electromagnetically-induced transparency in a three-level atomic system for hyperfine spectroscopy of upper states that are not directly coupled to the ground state. The three levels form a ladder system: the probe laser couples the ground state to the lower excited state, while the control laser couples the two upper states. As the frequency of the control laser is scanned, the probe absorption shows transparency peaks whenever the control laser is resonant with a hyperfine level of the upper state. As an illustration of the technique, we measure hyperfine structure in the $7S_{1/2}$ states of $^{85}$Rb and $^{87}$Rb, and obtain an improvement of more than an order of magnitude over previous values.Comment: 7 pages, 6 figure

Laser cooling and trapping of Yb from a thermal source

We have successfully loaded a magneto-optic trap for Yb atoms from a thermal source without the use of a Zeeman slower. The source is placed close to the trapping region so that it provides a large flux of atoms that can be cooled and captured. The atoms are cooled on the ${^1S_0} \leftrightarrow {^1P_1}$ transition at 398.8 nm. We have loaded all seven stable isotopes of Yb into the trap. For the most abundant isotope ($^{174}$Yb), we load more than $10^7$ atoms into the trap within 1 s. For the rarest isotope ($^{168}$Yb) with a natural abundance of only 0.13%, we still load about $4 \times 10^5$ atoms into the trap. We find that the trap population is maximized near a detuning of $-1.5\Gamma$ and field gradient of 75 G/cm.Comment: 4 figures, 6 page

Structure evaluation of computer human animation quality

The University of Bedfordshire in partial fulfilment of the requirements for the degree of Doctor of PhilosophyThis work will give a wide survey for various techniques that are present in the field of character computer animation, which concentrates particularly on those techniques and problems involved in the production of realistic character synthesis and motion. A preliminary user study (including Questionnaire, online publishing such as flicker.com, interview, multiple choice questions, publishing on Android mobile phone, and questionnaire analysis, validation, statistical evaluation, design steps and Character Animation Observation) was conducted to explore design questions, identify users' needs, and obtain a "true story" of quality character animation and the effect of using animation as useful tools in Education. The first set of questionnaires were designed to accommodate the evaluation of animation from candidates from different walks of life, ranging from animators, gamers, teacher assistances (TA), students, teaches, professionals and researchers using and evaluating pre-prepared animated character videos scenarios, and the study outcomes has reviewed the recent advances techniques of character animation, motion editing that enable the control of complex animations by interactively blending, improving and tuning artificial or captured motions. The goal of this work was to augment the students learning intuition by providing ways to make education and learning more interesting, useful and fun objectively, in order to improve students’ respond and understanding to any subject area through the use of animation also by producing the required high quality motion, reaction, interaction and story board to viewers of the motion. We present a variety of different evaluation to the motion quality by measuring user sensitivity, observations to any noticeable artefact, usability, usefulness etc. to derive clear useful guidelines from the results, and discuss several interesting systematic trends we have uncovered in the experimental data. We also present an efficient technique for evaluating the capability of animation influence on education to fulfil the requirements of a given scenario, along with the advantages and the effect on those deficiencies of some methods commonly used to improve animation quality to serve the learning process. Finally, we propose a wide range of extensions and statistical calculation enabled by these evaluation tools, such as Wilcoxon, F-test, T-test, Wondershare Quiz creator (WQC), Chi square and many others explained with full details

Do accruals exacerbate information asymmetry in the market?

A considerable body of evidence, both archival and experimental, suggests that accounting accruals are heterogeneously interpreted by investors. In this study, I examine whether the information asymmetry among investors arising from this heterogeneous interpretation, implied in these empirical results, affects transactions costs in the form of the bid-ask spread and its adverse selection component. I examine this impact both, in general, for all trading activity occurring for a firm over a continuous flow of information during the year and around the first release of accrual information for each quarter. The results of the study provide empirical evidence of a positive association between the adverse selection component of the bid-ask spread and accruals in the yearly analysis. The results of the quarterly event tests conducted both around earnings announcements and the 10-Q/10-K filing dates indicate that the increase in the adverse selection component of the spread is positively linked to the absolute magnitude of total accruals. Documenting the existence of such a real cost of accruals provides a transactions cost basis for understanding why cost of capital increases with accrual activity (Dechow et al. 1996, Francis et al. 2005) as well as suggesting that the information asymmetries associated with such activity merit serious attention of accounting policy maker

Voice quality features in the production of pharyngeal consonants by Iraqi Arabic speakers

PhD ThesisThis study investigates nasalisation and laryngealisation in the production of pharyngeal consonants in Iraqi Arabic (IA) and as potential voice quality (VQ) settings of IA speakers in general. Pharyngeal consonants have been the subject of investigation in many studies on Arabic, primarily due to the wide range of variation in their realisation across dialects, including approximant, fricative, and stop variants. This is the first quantitative study of its kind to extend these findings to IA and to investigate whether any of the variants and/or VQ features are dialect- specific. The study offers a detailed auditory and acoustic account of the realisations of pharyngeal consonants as produced by nine male speakers of three Iraqi dialects: Baghdad (representing Central gelet), Basra (representing Southern gelet) and Mosul (representing Northern qeltu) (Blanc, 1964; Ingham, 1997). Acoustic cues of nasalisation and phonation types are investigated in isolated vowels, oral, nasal, and pharyngeal environments in order to unravel the source of the nasalised and laryngealised VQ percept and to establish whether their manifestations are categorical or particular to certain contexts. Results suggest a range of realisations for the pharyngeals that are conditioned by word position and dialect. Regardless of realisation, VQ measurements suggest that: 1- nasalisation increases when pharyngeals are adjacent to nasals, beyond what is expected of a nasal environment; 2- vowels neighbouring pharyngeals show more nasalisation than in oral environments; 3- vowels in pharyngeal contexts and isolation show more laryngealisation compared with nasal and oral contexts; 4- both nasals and pharyngeals show progressive effect of nasalisation, and pharyngeals show a progressive effect of laryngealisation; 5- /ħ/ shows more nasalisation but less laryngealisation effect on neighbouring vowels than /ʕ/; and 6- Baghdad speech is the most nasalised and laryngealised and Basra speech the least. These results coincide with observations on Muslim Baghdadi gelet having a guttural quality (Bellem, 2007). The study reveals that the overall percept of a nasalised and laryngealised VQ in IA is a local feature rather than a general vocal setting