Demonstration of action-potential-producing cells in the rat pineal gland in vitro and their regulation by norepinephrine and nitric oxide

PURPOSE: The purpose of this study was to analyse donor and time dependent variations in the frequencies of radiation-induced aberrations in chromosomes 1 and 2. MATERIALS AND METHODS: Human lymphocytes from two donors were irradiated with 1 and 2 Gy of X-rays. Chromosomal aberrations were scored in chromosomes 1 and 2 painted with different fluorochromes and in Giemsa stained cells. Two time displaced experiments were performed with lymphocytes of each donor. RESULTS: In cells of both donors chromosome 1 was generally more frequently involved in translocations than chromosome 2. This result was not always reproducible. Chromosome 2 showed a higher frequency of acentric fragments, especially following a dose of 1 Gy. Again interexperimental variations were observed. No differences between the two chromosomes were seen with regard to other aberration types. Both chromosomes showed less dicentrics and more acentric fragments than proportional to their DNA content. CONCLUSIONS: Chromosomes 1 and 2 show a different sensitivity to ionizing radiation. The difference is dependent on the aberration type and is not always reproducible. This variability could contribute to the difficulty in reaching a consensus regarding the radiosensitivity of individual chromosomes.     

Tooling competence a key competition factor

High-quality tools are needed for volume production of PM parts. GKN Sinter Metals has created a central tool shop near Bonn to supply several European production sites. Klaus Vollrath reports…     

The emerging conceptualization of groups as information processors.

A selective review of research highlights the emerging view of groups as information processors. In this review, the authors include research on processing objectives, attention, encoding, storage, retrieval, processing response, feedback, and learning in small interacting task groups. The groups as information processors perspective underscores several characteristic dimensions of variability in group performance of cognitive tasks, namely, commonality—uniqueness of information, convergence–diversity of ideas, accentuation–attenuation of cognitive processes, and belongingness–distinctiveness of members. A combination of contributions framework provides an additional conceptualization of information processing in groups. The authors also address implications, caveats, and questions for future research and theory regarding groups as information processors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparing the rheology of native spider and silkworm spinning dope

Silk production has evolved to be energetically efficient and functionally optimized, yielding a material that can outperform most industrial fibres, particularly in toughness. Spider silk has hitherto defied all attempts at reproduction, despite advances in our understanding of the molecular mechanisms behind its superb mechanical properties. Spun fibres, natural and man-made, rely on the extrusion process to facilitate molecular orientation and bonding. Hence a full understanding of the flow characteristics of native spinning feedstock (dope) will be essential to translate natural spinning to artificial silk production. Here we show remarkable similarity between the rheologies for native spider-dragline and silkworm-cocoon silk, despite their independent evolution and substantial differences in protein structure. Surprisingly, both dopes behave like typical polymer melts. This observation opens the door to using polymer theory to clarify our general understanding of natural silks, despite the many specializations found in different animal species.     

Morphology and structure of silkworm cocoons

Silkworm cocoons are natural polymer fibre composites made from silk fibres and sericin binder. While silk is an interesting natural material per se, an understanding of the role of silk within one of its main functional applications in silkworm cocoons will provide inspiration and tools for the design of new artificial silk composites. Here, we describe in some detail the structure and morphology of the cocoons of 27 different species of silkworm. While cocoon morphology can be described very broadly as a nonwoven fibre composite, we demonstrate a diversity of structural features such as: the number and connectivity of layers through the cocoon wall thickness, the amount and distribution of sericin binder, the diameter and packing density of the silk fibres, the degree of orientation of the nonwoven structure, the distribution of larger holes within that structure, and the presence of calcium oxalate crystals.     

Spider webs inspiring soft robotics

In soft robotics, bio-inspiration ranges from hard- to software. Orb web spiders provide excellent examples for both. Adapted sensors on their legs may use morphological computing to fine-tune feedback loops that supervise the handling and accurate placement of silk threads. The spider''s webs embody the decision rules of a complex behaviour that relies on navigation and piloting laid down in silk by behaviour charting inherited rules. Analytical studies of real spiders allow the modelling of path-finding construction rules optimized in evolutionary algorithms. We propose that deconstructing spiders and unravelling webs may lead to adaptable robots able to invent and construct complex novel structures using relatively simple rules of thumb.