The effect of cooling rate on the impact performance and dynamic mechanical properties of rotationally molded metallocene catalyzed linear low density polyethylene

This article examines changes to the morphology of rotationally molded metallocene catalyzed linear low density polyethylene brought about by varying the cooling rate during processing. These changes in morphology lead to variations in the impact performance, which is reflected in the dynamic mechanical characteristics of the materials. Various analytical techniques are used in an attempt to explain the differences in impact behavior. Slow cooling is shown to result in high crystallinity, and in the formation of large spherulites, which in turn is detrimental to the impact performance of the material, particularly at low temperatures. The high crystallinity corresponds with a shift in the β transition of the material to a higher temperature, and is shown to result in a higher brittle–ductile transition. A case study was also carried out on samples from a finished part provided by an industrial molder, one section of which failed in a brittle manner when impact tested while the other failed in a ductile manner. Microscopy results showed that the brittle material had large spherulites at the inside surface, while the ductile material showed incipient degradation at this surface, which has previously been shown to be of benefit to impact strength in rotationally molded parts. Dynamic mechanical studies again showed a β transition at a higher temperature in the brittle samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1963–1971, 2006     

A color image watermarking framework for copyright protection of stereo images based on binocular just noticeable difference and LU decomposition

Multimedia Tools and Applications - The copyright protection of three-dimensional (3D) content is a matter of interest in artistic and creative works due to the rights of the holder for the...     

Guarino Guarini and Universal Mathematics

Guarini considered the mathematical studies to be of fundamental importance for all artists and scholars. His own knowledge of mathematics was vast and profound. The aim of this present paper is to show, through an analysis of the most substantial of his mathematical works, Euclides adauctus, along with the Appendix to this printed a few months later, the role that philosophical and mathematical studies had on his cultural formation, on the new and original research that he conducted, and on his teaching activities, while looking for traces of the mathematical sources that he consulted and cited that indicate which authors and works exerted the greatest influence on him.     

Trends in psychotherapy process research: Samples, measures, researchers, and classic publications.

Psychotherapy studies published in the Journal of Counseling Psychology (JCP) and the Journal of Consulting and Clinical Psychology (JCCP) between 1978 and 1992 were examined. Differences were found between the 2 journals. JCP published mostly process, outcome, and analog research, whereas JCCP published mostly outcome research. Most process and process-outcome studies across journals were of individual, brief therapy. Across the years, more diversity was evident in samples used in process research in terms of student status, gender, and race of clients and therapists. Three content areas were prominent in the process measures and classic studies: therapist techniques, therapist influence, and facilitative conditions. Lists are provided of the frequently used measures, most productive authors, and classic studies in process research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An output formation consensus control for leader–follower networked multi-agent systems under communication constraints and switching topologies

In this paper, the formation consensus problem for a class of leader–follower networked multi-agent systems under communication constraints and switching topologies is investigated. A networked predictive control scheme is proposed to achieve stability and output formation consensus with the switching topology, capable of compensating for data loss and time delays in the network. By equating the whole closed-loop networked multi-agent system with the proposed control scheme to the corresponding switched system, the sufficient and necessary condition of output formation consensus and stability for agents is given. Finally, using three-degree-of-freedom air-bearing spacecraft simulators as the control objects, the proposed scheme is demonstrated to be able to actively compensate for the communication constraints through numerical simulations, and it is also verified to have a good control performance by further realizing the formation task of the simulators through practical experiments.     

Experimental study of diffusion-based extraction from a cell suspension

A recently proposed application of microfluidics is the post-thaw processing of biological cells. Numerical simulations suggest that diffusion-based extraction of the cryoprotective agent dimethyl sulfoxide (DMSO) from blood cells is viable and more efficient than centrifugation, the conventional method of DMSO removal. In order to validate the theoretical model used in these simulations, a prototype was built and the flow of two parallel streams, a suspension of Jurkat cells containing DMSO and a wash stream that contained neither cells nor DMSO, was characterized experimentally. DMSO transport in a rectangular channel (depth 500 μm, width 25 mm and overall length 125 mm) was studied as a function of three dimensionless parameters: depth ratio of the streams, cell volume fraction in the cell solution, and the Peclet number (Pe) based on channel depth, average flow rate and the diffusion coefficient for DMSO in water. In our studies, values of Pe ranged from O(10³) to O(10⁴). Laminar flow was ensured by keeping the Reynolds number between O(1) and O(10). Experimental results based on visual and quantitative data demonstrate conclusively that a microfluidic device can effectively remove DMSO from liquid and cell laden streams without compromising cell recovery. Also, flow conditions in the microfluidic device appear to have no adverse effect on cell viability at the outlet. Further, the results demonstrate that we can predict the amount of DMSO removed from a given device with the theoretical model mentioned previously.     

Spanish Melon Landraces: Revealing Useful Diversity by Genomic,Morphological, and Metabolomic Analysis

Spain is a secondary centre of the diversification of the melon (Cucumis melo L.), with high diversity represented in highly appreciated landraces belonging to the Flexuosus and Ibericus groups. A collection of 47 accessions of Flexuosus, Chate, Piel de Sapo, Tendral, Amarillo, Blanco, and Rochet was analysed using a genotyping-by-sequencing (GBS) approach. A total of 66,971 quality SNPs were identified. Genetic analysis differentiated Ibericus accessions and exotic materials (Ameri, Momordica, Kachri, and Agrestis), while Flexuous accessions shared ancestry between them. Within the Ibericus group, no clear genomic distinction could be identified for the different landraces evaluated, with accessions of different landraces showing high genetic similarity. The morphological characterization confirmed that the external colour and fruit shape had been used as recognition patterns for Spanish melon landraces, but variability within a landrace exists. Differences were found in the sugars and acid and volatile profiles of the materials. Flexuosus and Chate melons at the immature commercial stage accumulated malic acid and low levels of hexoses, while Ibericus melons accumulated high contents of sucrose and citric acid. Specific trends could be identified in the Ibericus landraces. Tendral accumulated low levels of sugars and citric acid and high of malic acid, maintaining higher firmness, Rochet reached higher levels of sugars, and Amarillo tended to lower malic acid contents. Interestingly, high variability was found within landraces for the acidic profile, offering possibilities to alter taste tinges. The main volatile organic compounds (VOCs) in Flexuosus and Chate were aldehydes and alcohols, with clear differences between both groups. In the Ibericus landraces, general trends for VOC accumulation could be identified, but, again, a high level of variation exists. This situation highlights the necessity to develop depuration programs to promote on-farm in situ conservation and, at the same time, offers opportunities to establish new breeding program targets and to take advantage of these sources of variation.     

A single pass algorithm for clustering evolving data streams based on swarm intelligence

Existing density-based data stream clustering algorithms use a two-phase scheme approach consisting of an online phase, in which raw data is processed to gather summary statistics, and an offline phase that generates the clusters by using the summary data. In this article we propose a data stream clustering method based on a multi-agent system that uses a decentralized bottom-up self-organizing strategy to group similar data points. Data points are associated with agents and deployed onto a 2D space, to work simultaneously by applying a heuristic strategy based on a bio-inspired model, known as flocking model. Agents move onto the space for a fixed time and, when they encounter other agents into a predefined visibility range, they can decide to form a flock if they are similar. Flocks can join to form swarms of similar groups. This strategy allows to merge the two phases of density-based approaches and thus to avoid the computing demanding offline cluster computation, since a swarm represents a cluster. Experimental results show that the bio-inspired approach can obtain very good results on real and synthetic data sets.