Geographic variations in the composition of ivory of the African elephant (Loxodonta africana)

OBJECTIVES: The purpose of the present study was to compare the inclination of the occlusal plane with occlusal guidance as a contributing factor to masticatory movement. METHODS: Masticatory movements of 41 young adults were measured using a 3-D mandibular movement analysing system. The inclination of the occlusal plane was measured in the sagittal plane using a 3-D digitizer. The contribution of the occlusal guidance and the inclination of the occlusal plane to the direction of the masticatory path of closure was evaluated at various closing levels. RESULTS: The masticatory path of closure outside the intercuspal range was influenced mainly by the inclination of the occlusal plane, and the masticatory path of closure near the intercuspal range was only influenced by occlusal guidance. The so-called gliding type masticatory pattern was observed predominantly in subjects with a posteriorly inclined occlusal plane. In contrast, a chopping type masticatory pattern was observed predominantly in subjects with an anteriorly inclined occlusal plane. CONCLUSIONS: The contribution of the inclination of the occlusal plane to masticatory movement was greater than that of occlusal guidance throughout the closing phase except near the intercuspal range.     

Personnel selection and the prediction of error.

Summarizes a few trends in current personnel selection research and presents the rationale for a prediction model, taking advantage of the concept of under- and overpredictability. A noncognitive predictor of predictability was developed, using 224 male and female clerical workers, and used to subgroup a cross-validation sample of 110 Ss into underpredictables, accurately predictables, and overpredictables. Product-moment correlations between the unweighted sum of 6 cognitive predictors (subtests on the Purdue Clerical Adaptability Test) and a criterion measure of overall job performance were .26, .48, and .40 for the 3 subgroups, respectively. This compared favorably with a correlation of .25 before subgrouping and .34, for the 6 cognitive predictors and 2 noncognitive predictor scales (used to develop the predictor of predictability). (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Poly(pent‐1‐ene) Synthesized with the Syndiospecific Catalyst i‐Pr(Cp)(9‐Flu)ZrCl2/MAO

1‐Pentene was polymerized with the syndiospecific catalyst system i‐PrC(Cp)(9‐fluorenyl)ZrCl₂/MAO. The molar mass of the resulting polymers depends strongly on the reaction temperature and decreases from M̄_w = 126 000 at 0°C to M̄_w = 46 000 at 100°C, but is more or less independent of the monomer and the MAO concentration. The influence of reaction temperature and concentrations of MAO and monomer on the type of end‐groups generated during the chain termination, as well as on the type of stereoerror, was investigated. The degree of tacticity was dependent on the polymerization temperature with [rrrr] > 0.99 at 0°C and [rrrr] = 0.75 at 100°C.     

Are You Listening to Your Spanish Speakers? How Spanish Speakers in the U.S. Say U.S. Addresses

This work presents research analyzing the structure of how U.S. addresses are spoken by Spanish speakers living in the U.S. The findings, based on live-call recordings of Spanish speakers interacting with call center agents, reveal that an English-like format with the street number spoken before the street name was used in 91% of the cases, even though the street number was said in Spanish 100% of the time. How audio prompt wording can be used to influence the way addresses are spoken and also how street names consisting of numbers are said are possible areas for future study. In addition, some best practices related to dialog design for bilingual Spanish-English speech recognition applications are also revealed during this study.     

Bayesian Control Chart for Nonconformities

The c‐chart or the control chart for nonconformities is designed for the case where one deals with the number of defects or nonconformities observed. A control chart can be developed for the total or average number of nonconformities per unit, which is well modeled by the Poisson distribution. In this paper the c‐chart will be studied, where the usual operation of the c‐chart will be extended by introducing a Bayesian approach for the c‐chart. Control chart limits, average run lengths, and false alarm rates will be determined by using a Bayesian method. These results will be compared with the results obtained when using the classical (frequentist) method. Copyright © 2014 John Wiley & Sons, Ltd.     

Homopolymerization of Higher 1‐Olefins with Metallocene/MAO Catalysts

Linear 1‐olefins from 1‐pentene to 1‐octadecene are polymerized by non‐stereospecific Cp₂HfCl₂ ( 1 ), syndiospecific Me₂C(Cp)(9‐fluorenyl)ZrCl₂ ( 2 ) and isospecific Et(Ind)₂ZrCl₂ ( 3 ) catalysts in the presence of MAO. The molecular weight of the resulting polymers (GPC) is highly dependent on the nature of the catalyst, but more or less independent of the monomer chain length. The stereoregularity of the poly(1‐olefins) obtained with 2 and 3 as determined by NMR spectroscopy decreases linearly with increasing monomer chain length. A decrease in isotacticity occurs for the poly(1‐olefins) synthesized with 3 when increasing the catalyst concentration. Vinylidene, 1,2‐disubstituted and 1,1,2‐trisubstituted double bonds attributed to different chain termination mechanisms are generated during the polymerization processes.     

Histogenesis of the chequered pattern of ivory of the African elephant (Loxodonta africana)

This study aimed to propose a hypothesis on the events which lead to the development of the characteristic chequered pattern of elephant ivory. Twenty fragments of ivory and six elephant tusks were obtained through the National Parks Board of South Africa. Polished surfaces were prepared in sagittal and longitudinal planes and the characteristics of the distinctive chequered pattern described. Light- and electron-microscopical techniques and image analyses were employed to determine the morphological basis of the pattern and to describe the spatial distribution, density and morphology of the dentinal tubules. These investigations showed that the distinctive pattern was the result of the sinusoidal, centripetal course followed by dentinal tubules. The apical, slanted part of the sinusoidal curve is the result of the centripetally moving odontoblast, which, during formation of ivory, progresses towards the centre of the tusk on a decreasing circumference. It is suggested that this leads to cell crowding, increased pressure between odontoblasts and subsequent apical movement of their cell bodies, cell degeneration and fusion. Odontoblastic degeneration and fusion probably relieve the pressure between the crowded odontoblasts by reducing their numbers and the remaining odontoblasts now orientate their centripetal course towards the tip of the tusk, thereby forming the anterior-directed part of the sinusoidal path of the tubule. As odontoblasts progress centripetally the diameter of the pulpal cavity decreases further and the processes of apical movement, fusion and degeneration of odontoblasts are repeated. This occurs until the pulpal cavity is obliterated.     

Particle Image Velocimetry Measurements within a Laboratory-Generated Swash Zone

A particle image velocimetry (PIV) technique is used to make vertically resolved two-dimensional measurements in swash zone flows, which are notoriously recalcitrant to quantitative measurement. The PIV implementation directs the light sheet into the measurement region from beneath the beach thus avoiding issues of free surface diffraction effects. Fluorescent particles and an optical filter are used to ensure that only particles, and not bubbles or free surface anomalies, are imaged. The spatially and temporally resolved velocity fields measured in a plunging and spilling wave-driven swash zone are used to investigate the boundary layer structure of the mean and turbulent quantities as well as the phase evolution of the bed shear stress, near-bed turbulent kinetic energy, and the dissipation. Results suggest that vertical structure in spilling and plunging wave forced swash zones are similar. The uprush phase is dominated by bore-generated and bore-advected turbulence, which evolves analogously to grid turbulence, while the downrush phase is ultimately dominated by boundary layer generated turbulence, which compares well near-bed with classic flat plate boundary layer theory.     

A technique of measuring and correcting emittance dilutions due to accelerator structure misalignments

This paper describes a method of reducing the transverse emittance dilution in linear colliders due to transverse wakefields arising from misaligned accelerator structures. The technique is a generalization of the Wake-Free [T.O. Raubenheimer, Nucl. Instr. and Meth. A 306 (1991) 61] correction algorithm. The structure errors are measured locally by varying the bunch charge and/or bunch length and measuring the change in the beam trajectory. The structure errors can then be corrected by varying the trajectory or moving the structures. The results of simulations are presented demonstrating the viability of the technique.