A rational model of the surface swept by a curve*

This paper shows how to construct a rational Bezier model of a swept surface that interpolates N frames (i.e., N position/orientation pairs) of a fixed rational space curve c(s) and maintains the shape of the curve at all intermediate points of the sweep. Thus, the surface models an exact sweep of the curve, consistent with the given data. The primary novelty of the method is that this exact modeling of the sweep is achieved without sacrificing a rational representation for the surface. Through a simple extension, we also allow the sweeping curve to change its size through the sweep. The position, orientation, and size of the sweeping curve can change with arbitrary continuity (we use C² continuity in this paper). Our interpolation between frames has the classical properties of Bezier interpolation, such as the convex hull property and linear precision. This swept surface is a useful primitive for geometric design. It encompasses the surface of revolution and extruded surface, but extends them to arbitrary sweeps. It is a useful modeling primitive for robotics and CAD/CAM, using frames generated automatically by a moving robot or tool.     

Identification of multiple human calcitonin receptor isoforms: heterologous expression and pharmacological characterization

The human breast carcinoma cell line T47D is known to express high-affinity calcitonin receptors (CTRs). PCR amplification of the CTR cDNA from T47D mRNA resulted in the identification of two different cDNAs that encode distinct receptor isoforms, h alpha CTR and h beta CTR. The two cDNAs are identical except that the h alpha CTR cDNA contains a 48 bp insert sequence that encodes a 16 amino acid domain in the first cytosolic loop of the receptor. Stable transfection of each receptor cDNA into murine erythroleukaemia (MEL) cells resulted in the expression of receptors with high affinity for radiolabelled salmon calcitonin (h alpha CTR Kd 0.09 nM, h beta CTR Kd 0.12 nM). Ligand competition binding studies did not reveal any significant pharmacological difference between the receptor isoforms. In transfected MEL cells and COS-1 cells the h beta CTR isoform was expressed at tenfold higher levels than the h alpha CTR. A reporter gene assay that monitored the coupling of CTR to adenylate cyclase by increases in beta-galactosidase activity indicated that both receptors were able to stimulate cyclic AMP production in response to ligand binding.     

A new analytical approach to predict spacing selection in lamellar and rod eutectic systems

The Jackson and Hunt (JH) theory has been modified to relax the assumption of isothermal solid/liquid interface used in their treatment. Based on the predictions of this modified theory, the traditional definitions of regular and irregular eutectics are revised. For regular eutectics, the new model identifies a range of spacing within the limits defined by the minimum undercooling of the α and β phases. For the irregular Al-Si eutectic system, two different spacing selection mechanisms were identified: (1) for a particular growth rate, a nearly isothermal interface can be achieved at a unique minimum spacing λ _I ; (2) the average spacing (λ _av >λ _I ) is essentially dictated by the undercooling of the faceted phase. Based on the modified theoretical model, a semiempirical expression has been developed to account for the influence of the temperature gradient, which is dominant in the irregular Al-Si system. The behavior of the Fe-Fe₃C eutectic is also discussed. The theoretical calculations have been found to be in good agreement with the published experimental measurements.     

On the compatibility of polysaccharide/maleic copolymer blends. II. Thermal behavior of pullulan‐containing blends

The compatibility of pullulan with maleic acid/vinyl acetate copolymers in the solid state in the form of thin films was studied with thermogravimetry, differential scanning calorimetry, infrared spectroscopy, and optical microscopy. With respect to morphology, blends with a content of pullulan greater than 85 wt % exhibited an even distribution of finely dispersed particles. The thermal properties were dependent on the mixing ratio, and the interactions between components were quite pronounced in the pullulan‐rich blends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1782–1791, 2002     

Combined Particle Image Velocimetry/Planar Laser Induced Fluorescence for Integral Modeling of Buoyant Jets

Combined particle image velocimetry and planar laser induced fluorescence is an efficient measurement approach for laboratory studies in environmental hydraulics. The coupling of the two well-known techniques enables synchronized planar measurements of flow velocity and concentration in an area yielding both their mean distribution as well as turbulence covariance. In this paper, the merits and limitations of the combination are first discussed. An example of experimental setup is then briefly described. Finally, an application is demonstrated for the integral modeling of an inclined round buoyant jet that takes full advantage of the capability of the combined approach.     

A review of distributed architectures for networked virtual reality

The aims of this paper are twofold. First, it identifies the general requirements of future large-scale distributed virtual reality (VR) systems based on an analysis of current VR systems, of more general distributed systems platforms and a consideration of the key issues of scale and heterogeneity. These requirements subsequently inform the development of a general VR reference architecture; and a framework which identifies the key software components which will comprise future distributed VR systems. Second, it uses this reference architecture as a vehicle for conducting a broad review of current distributed VR products and research prototypes. The review covers twelve well known VR systems and intended as a general resource for researchers entering the field. These systems are: AVIARY, BrickNet, DIVE, dVS, MASSIVE, the MR Toolkit, NPSNET, Superscape, VEOS, VUE, WAVES and World Toolkit. The review also identifies relevant standards in the areas of computer graphics and distributed systems. The paper finishes by drawing out a number of more general conclusions from the review including the urgent need to conduct research into the subjects of security and resource discovery for distributed VR systems.     

Evolution and validation of a behavioral decision theory measurement approach to achievement, power, and affiliation.

Extended the present author's (see record 1981-23696-001) research on a behavioral decision theory approach to the measurement of need for Affiliation (nAff), need for Power (nPow), and need for Achievement (nAch). In a decision-making exercise, S made decisions concerning the attractiveness of 24 hypothetical jobs that were described in terms of Aff, Pow, and Ach. Extensive psychometric data gathered from 1,741 Ss (partners in an accounting firm, military officers and cadets, high school students, undergraduates, and graduate students) were also reported. The modified measure was reliable and free of social desirability bias. The Aff, Pow, and Ach scores were significantly correlated with several objective behaviors and an alternative measure of the motives. Group difference tests among the 7 samples also supported the validity of the measurement approach. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Enhanced incorporation of exogenous arachidonic acid into phosphatidylinositol and other phospholipids during the early stages of thrombin-induced aggregation in gerbil platelets

The degradation of platelet phospholipids via phospholipase activity is known to occur during thrombin-induced platelet aggregation. Both phosphatidylinositol and phosphatidylcholine are considered to be sources of the released arachidonic acid which becomes a substrate for prostaglandin and thromboxane A₂ formation. In this work, the effect of thrombin on the incorporation of exogenous arachidonic acid into platelet membrane phospholipids was studied. Suspensions of gerbil platelets were incubated in aggregometer cuvettes with [¹⁴C] arachidonic acid in the absence or presence of thrombin, and product formation was monitored by thin layer chromatography and scintillation counting. Within 30 sec, the entry of arachidonic acid into phosphatidylinositol was increased by 165% in thrombin-stimulated platelets over controls. Under identical conditions, the incorporation into phosphatidylcholine was increased by only 57%. These results suggest that the incorporation of exogenous arachidonic acid via lysophosphatidylinositol and lysophosphatidylcholine acyltransferase activities may be intimately associated with thrombin-induced platelet aggregation in the gerbil. Presented in part at the 73rd annual AOCS meeting, Toronto, 1982.