117,327 research outputs found
Optimisation by Evolutionary Algorithms of Free-Layer Damping Treatments on Plates
No full textThe problem of controlling or reducing vibration levels is very common in many different applications. From costly aeroplane fuselages to cheap domestic appliances the prob- lem can be tackled with the appropriate use of free layer damping treatments (FLDT).1 This technique, based on the distribution of layers of visoelastic material on the vibrating parts, is frequently adopted since it is cheap, efficient and easily applicable either at the design stage or in situ as a cor- rective measure. Due to these advantages and few limitations, not much care is taken to optimise the material distribution. Conversely, the necessity to produce lighter and quieter products will force the designer to optimise these treatments too. Under these circumstances, the most appropriate optimi- sation objectives seem to be the maximisation of the achiev- able damping levels and the minimisation of the amount of added material. In this work the potential of the genetic algorithm for the determination of th
Cellular biomechanics impairment in keratinocytes is associated with a C-terminal truncated desmoplakin: An atomic force microscopy investigation
No full textIn a tissue continuously challenged by mechanical stresses, such as the skin or the heart, cells perceive information about their microenvironment through several adhesive protein complexes and activate cell-signaling events to maintain tissue cohesion. Consequently, alteration of cell adhesion components leads to aberrant assembly of the associated cytoplasmic scaffolding and signaling pathways, which may reflect changes to the tissue physiology and mechanical resistance. Desmoplakin is an essential component of the cell-cell junction, anchoring the desmosomal protein complex to the intermediate filaments (IFs). Inherited mutations in desmoplakin are associated with both heart and skin disease (cardiocutaneous syndrome). In this study, we investigated the mechanical properties of human keratinocytes harboring a cardiocutaneous-associated homozygous C-terminal truncation in desmoplakin (JD-1) compared to a control keratinocyte line (K1). Using Single Cell Force Spectroscopy (SCFS) AFM-based measurements, JD-1 keratinocytes displayed an overall alteration in morphology, elasticity, adhesion capabilities and viscoelastic properties, highlighting the profound interconnection between the adhesome pathways and the IF scaffold
DNA-protein interaction dynamics at the Lamin B2 replication origin
No full textTo date, a complete understanding of the molecular events leading to DNA replication origin activation in mammalian cells still remains elusive. In this work, we report the results of a high resolution chromatin immunoprecipitation study to detect proteins interacting with the human Lamin B2 replication origin. In addition to the pre-RC component ORC4 and to the transcription factors USF and HOXC13, we found that 2 components of the AP-1 transcription factor, c-Fos and c-Jun, are also associated with the origin DNA during the late G1 phase of the cell cycle and that these factors interact with ORC4. Both DNA replication and AP-1 factor binding to the origin region were perturbed by cell treatment with merbarone, a topoisomerase II inhibitor, suggesting that DNA topology is essential for determining origin function
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Evolution of the primate cathelicidin. Correlation between structural variations and antimicrobial activity.
No full textCathelicidin genes homologous to the human CAMP gene, coding for the host defense peptide LL-37, have been sequenced and analyzed in 20 primate species, including Great Apes, hylobatidae, cercopithecidae, callithricidae, and cebidae. The region corresponding to the putative mature antimicrobial peptide is subject to a strong selective pressure for variation, with evidence for positive selection throughout the phylogenetic tree relating the peptides, which favors alterations in the charge while little affecting overall hydrophobicity or amphipathicity. Selected peptides were chemically synthesized and characterized, and two distinct types of behavior were observed. Macaque and leaf-eating monkey RL-37 peptides, like other helical antimicrobial peptides found in insect, frog, and mammalian species, were unstructured in bulk solution and had a potent, salt and medium independent antimicrobial activity in vitro, which may be the principal function also in vivo. Human LL-37 and the orangutan, hylobates, and callithrix homologues instead showed a salt-dependent structuring and likely aggregation in bulk solution that affected antimicrobial activity and its medium dependence. The two types of peptides differ also in their interaction with host cells. The evolution of these peptides has thus resulted in distinct mechanisms of action that affect the direct antimicrobial activity andmayalso modulate accessory antimicrobial functions due to interactions with host cells
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