RF-MEMS switch actuation pulse optimization using Taguchi's method

Copyright @ 2011 Springer-VerlagReliability and longevity comprise two of the most important concerns when designing micro-electro-mechanical-systems (MEMS) switches. Forcing the switch to perform close to its operating limits underlies a trade-off between response bandwidth and fatigue life due to the impact force of the cantilever touching its corresponding contact point. This paper presents for first time an actuation pulse optimization technique based on Taguchi’s optimization method to optimize the shape of the actuation pulse of an ohmic RF-MEMS switch in order to achieve better control and switching conditions. Simulation results show significant reduction in impact velocity (which results in less than 5 times impact force than nominal step pulse conditions) and settling time maintaining good switching speed for the pull down phase and almost elimination of the high bouncing phenomena during the release phase of the switch

Resistive damping implementation as a method to improve controllability in stiff ohmic RF-MEMS switches

This paper presents in detail the entire procedure of calculating the bias resistance of an ohmic RF-MEMS switch, controlled under resistive damping (charge drive technique). In case of a very stiff device, like the North Eastern University switch, the actuation control under resistive damping is the only way to achieve controllability. Due to the short switching time as well as the high actuation voltage, it is not practical to apply a tailored control pulse (voltage drive control technique). Implementing a bias resistor of 33 MΩ in series with the voltage source, the impact velocity of the cantilever has been reduced 80 % (13.2 from 65.9 cm/s), eliminating bouncing and high initial impact force during the pull-down phase. However, this results in an affordable cost of switching time increase from 2.38 to 4.34 μs. During the release phase the amplitude of bouncing has also been reduced 34 % (174 from 255 nm), providing significant improvement in both switching operation phases of the switch. © 2013 Springer-Verlag Berlin Heidelberg

Knowledge-based energy functions for computational studies of proteins

This chapter discusses theoretical framework and methods for developing knowledge-based potential functions essential for protein structure prediction, protein-protein interaction, and protein sequence design. We discuss in some details about the Miyazawa-Jernigan contact statistical potential, distance-dependent statistical potentials, as well as geometric statistical potentials. We also describe a geometric model for developing both linear and non-linear potential functions by optimization. Applications of knowledge-based potential functions in protein-decoy discrimination, in protein-protein interactions, and in protein design are then described. Several issues of knowledge-based potential functions are finally discussed.Comment: 57 pages, 6 figures. To be published in a book by Springe

A new, large-bodied omnivorous bat (Noctilionoidea: Mystacinidae) reveals lost morphological and ecological diversity since the Miocene in New Zealand

A new genus and species of fossil bat is described from New Zealand's only pre-Pleistocene Cenozoic terrestrial fauna, the early Miocene St Bathans Fauna of Central Otago, South Island. Bayesian total evidence phylogenetic analysis places this new Southern Hemisphere taxon among the burrowing bats (mystacinids) of New Zealand and Australia, although its lower dentition also resembles Africa's endemic sucker-footed bats (myzopodids). As the first new bat genus to be added to New Zealand's fauna in more than 150 years, it provides new insight into the original diversity of chiropterans in Australasia. It also underscores the significant decline in morphological diversity that has taken place in the highly distinctive, semi-terrestrial bat family Mystacinidae since the Miocene. This bat was relatively large, with an estimated body mass of ~40 g, and its dentition suggests it had an omnivorous diet. Its striking dental autapomorphies, including development of a large hypocone, signal a shift of diet compared with other mystacinids, and may provide evidence of an adaptive radiation in feeding strategy in this group of noctilionoid bats

Analysis of the Effects of Polymorphism on Pollen Profilin Structural Functionality and the Generation of Conformational, T- and B-Cell Epitopes

An extensive polymorphism analysis of pollen profilin, a fundamental regulator of the actin cytoskeleton dynamics, has been performed with a major focus in 3D-folding maintenance, changes in the 2-D structural elements, surface residues involved in ligands-profilin interactions and functionality, and the generation of conformational and lineal B- and T-cell epitopes variability. Our results revealed that while the general fold is conserved among profilins, substantial structural differences were found, particularly affecting the special distribution and length of different 2-D structural elements (i.e. cysteine residues), characteristic loops and coils, and numerous micro-heterogeneities present in fundamental residues directly involved in the interacting motifs, and to some extension these residues nearby to the ligand-interacting areas. Differential changes as result of polymorphism might contribute to generate functional variability among the plethora of profilin isoforms present in the olive pollen from different genetic background (olive cultivars), and between plant species, since biochemical interacting properties and binding affinities to natural ligands may be affected, particularly the interactions with different actin isoforms and phosphoinositides lipids species. Furthermore, conspicuous variability in lineal and conformational epitopes was found between profilins belonging to the same olive cultivar, and among different cultivars as direct implication of sequences polymorphism. The variability of the residues taking part of IgE-binding epitopes might be the final responsible of the differences in cross-reactivity among olive pollen cultivars, among pollen and plant-derived food allergens, as well as between distantly related pollen species, leading to a variable range of allergy reactions among atopic patients. Identification and analysis of commonly shared and specific epitopes in profilin isoforms is essential to gain knowledge about the interacting surface of these epitopes, and for a better understanding of immune responses, helping design and development of rational and effective immunotherapy strategies for the treatment of allergy diseases. [EN]This study was supported by the following European Regional Development Fund co-financed grants: MCINN BFU 2004-00601/BFI, BFU 2008-00629, BFU2011-22779, CICE (Junta de Andalucía) P2010-CVI15767, P2010-AGR6274 and P2011-CVI-7487, and by the coordinated project Spain/Germany MEC HA2004-0094. JCJ-L thanks Spanish CSIC and the European Marie Curie research program for his I3P-BPD-CSIC, and PIOF-GA-2011-301550 grants, respectively.Peer reviewe