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Search Results: 1 - 10 of 201181 matches for " Mikel P Gonzales "
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Conservation in the face of diversity: multistrain analysis of an intracellular bacterium
Michael J Dark, David R Herndon, Lowell S Kappmeyer, Mikel P Gonzales, Elizabeth Nordeen, Guy H Palmer, Donald P Knowles, Kelly A Brayton
BMC Genomics , 2009, DOI: 10.1186/1471-2164-10-16
Abstract: These comparisons revealed that A. marginale has a closed-core genome with few highly plastic regions, which include the msp2 and msp3 genes, as well as the aaap locus. Comparison of the Florida and St. Maries genome sequences found that SNPs comprise 0.8% of the longer Florida genome, with 33.5% of the total SNPs between all five strains present in at least two strains and 3.0% of SNPs present in all strains except Florida. Comparison of genomes from three strains of Mycobacterium tuberculosis, Bacillus anthracis, and Nessieria meningiditis, as well as four Chlamydophila pneumoniae strains found that 98.8%–100% of SNPs are unique to each strain, suggesting A. marginale, with 76.0%, has an intermediate level of strain-specific SNPs. Comparison of genomes from other organisms revealed variation in diversity that did not segregate with the environmental niche the bacterium occupies, ranging from 0.00% to 8.00% of the larger pairwise-compared genome.Analysis of multiple A. marginale strains suggests intracellular bacteria have more variable SNP retention rates than previously reported, and may have closed-core genomes in response to the host organism environment and/or reductive evolution.While the recent boom in genome sequencing projects has provided a wealth of information about bacterial metabolism and evolution, we know little about interstrain variation. A firm understanding of the rates and sites of variation is useful in determining genotypic differences associated with phenotypic traits and in formulating control strategies for a number of pathogens. Further, knowledge about the pan-genome of organisms will aid in determining the core genomic requirements, as well as shed more light on events that occur in the various environmental niches bacteria occupy.Most studies of bacterial diversity to date have either utilized specific genomic loci [1,2] or have examined metagenomics of specific environmental niches [3,4]. While these types of studies help elucidate th
Phlébotomes du Nicaragua: I. Description de la femelle de Lutzomyia zeledoni Young et Murillo, 1984 (Diptera, Psychodidae), et implication épidémiologique de la présence de Lutzomyia longipalpis sur la fa?ade Pacifique
Le Pont, F.;Desjeux, P.;Gonzales, A.;
Memórias do Instituto Oswaldo Cruz , 1987, DOI: 10.1590/S0074-02761987000200015
Abstract: the authors describe the female of lutzomyia zeledoni young & murillo, 1984 from the group vespertilionis theodor, 1965. this species was cpatured in the peridomestic environment together with lutzomyia longipalpis lutz & neiva, 1912 here reported for the first time in nicaragua. emphasis is placed on the epidemiological importance of this latter species collected in abundance at several sites along the pacific coast.
Patterns of Chemical Diversity in the Mediterranean Sponge Spongia lamella
Charlotte Noyer, Olivier P. Thomas, Mikel A. Becerro
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0020844
Abstract: The intra-specific diversity in secondary metabolites can provide crucial information for understanding species ecology and evolution but has received limited attention in marine chemical ecology. The complex nature of diversity is partially responsible for the lack of studies, which often target a narrow number of major compounds. Here, we investigated the intra-specific chemical diversity of the Mediterranean sponge Spongia lamella. The chemical profiles of seven populations spreading over 1200 km in the Western Mediterranean were obtained by a straightforward SPE-HPLC-DAD-ELSD process whereas the identity of compounds was assessed by comparison between HPLC-MS spectra and literature data. Chemical diversity calculated by richness and Shannon indexes differed significantly between sponge populations but not at a larger regional scale. We used factor analysis, analysis of variance, and regression analysis to examine the chemical variability of this sponge at local and regional scales, to establish general patterns of variation in chemical diversity. The abundance of some metabolites varied significantly between sponge populations. Despite these significant differences between populations, we found a clear pattern of increasing chemical dissimilarity with increasing geographic distance. Additional large spatial scale studies on the chemical diversity of marine organisms will validate the universality or exclusivity of this pattern.
Frequency Noise Suppression of a Single Mode Laser with an Unbalanced Fiber Interferometer for Subnanometer Interferometry
Radek míd,Martin íek,Betislav Mikel,Ondej íp
Sensors , 2015, DOI: 10.3390/s150101342
Abstract: We present a method of noise suppression of laser diodes by an unbalanced Michelson fiber interferometer. The unstabilized laser source is represented by compact planar waveguide external cavity laser module, ORIONTM (Redfern Integrated Optics, Inc.), working at 1540.57 nm with a 1.5-kHz linewidth. We built up the unbalanced Michelson interferometer with a 2.09 km-long arm based on the standard telecommunication single-mode fiber (SMF-28) spool to suppress the frequency noise by the servo-loop control by 20 dB to 40 dB within the Fourier frequency range, remaining the tuning range of the laser frequency.
Mechanical loading of adipose derived stromal cells causes cell alignment  [PDF]
David A. Gonzales, Alice S. Ferng, Chris P. Geffre, Jamie L. Borg, Michael Miller, John A. Szivek
Journal of Biomedical Science and Engineering (JBiSE) , 2011, DOI: 10.4236/jbise.2011.45045
Abstract: Osteoarthritis is a debilitating disease that affects hundreds of millions of people worldwide. Current research involving growth and characterization of adipose derived stromal cells (ADSC) in vitro offers a potential solution for the treatment of cartilage de-fects that will allow patients to return to the physical activities they were involved in. Studies have shown that fibroblast cells grown in vitro respond to cyclic mechanical stretching by orienting in a direction perpendicular to the direction of stretch. ADSCs were isolated from human peripatellar adipose tissue discards. Cells were cultured until confluent and seeded at a density of approximately 105 cells in silicone wells pretreated with ProNectin-F Plus. After stret-ching, relative alignment of the cells was ascertained using imaging software. Stretching cells for 3, 4, 8 and 12 hours resulted in noticeable cellular alignment of approximately 60? relative to the direction of loading. Cell alignment is crucial for developing tis-sue-engineered cartilage that has similar mechanical properties to native cartilage. Mechanically loading cells is one method to achieve cell alignment. Since cell differentiation will be initiated after alignment, the resulting chondrocytes will be aligned, leading to organized collagen formation and resulting in a hya-line-like cartilage structure.
Invalid Permutation Tests
Mikel Aickin
International Journal of Mathematics and Mathematical Sciences , 2010, DOI: 10.1155/2010/769780
Abstract: Permutation tests are often presented in a rather casual manner, in both introductory and advanced statistics textbooks. The appeal of the cleverness of the procedure seems to replace the need for a rigorous argument that it produces valid hypothesis tests. The consequence of this educational failing has been a widespread belief in a “permutation principle”, which is supposed invariably to give tests that are valid by construction, under an absolute minimum of statistical assumptions. Several lines of argument are presented here to show that the permutation principle itself can be invalid, concentrating on the Fisher-Pitman permutation test for two means. A simple counterfactual example illustrates the general problem, and a slightly more elaborate counterfactual argument is used to explain why the main mathematical proof of the validity of permutation tests is mistaken. Two modifications of the permutation test are suggested to be valid in a very modest simulation. In instances where simulation software is readily available, investigating the validity of a specific permutation test can be done easily, requiring only a minimum understanding of statistical technicalities.
La democracia electrónica
Mikel Barreda
IDP , 2008,
Abstract: La irrupción de las tecnologías de la información y la comunicación (TIC) en la arena política ha despertado un amplio interés en relación con su potencialidad para transformar y mejorar la calidad de las democracias actuales. Los artículos de este monográfico abordan, desde distintos enfoques, algunos temas clave de estudio en el campo de la democracia electrónica, como son los de participación, deliberación y uso de las TIC por parte de los partidos políticos.
God's Reality, Matters of Fact and D.Z. Phillips
Burley, Mikel
Ars Disputandi : the Online Journal for Philosophy of Religion , 2011,
Spectrum of density fluctuations in Brans-Dicke chaotic inflation
Mikel Susperregi
Physics , 1996, DOI: 10.1103/PhysRevD.55.560
Abstract: In the context of Brans--Dicke theories, eternal inflation is described in such a way that the evolution of the inflaton field is determined by the value of the Planck mass in different regions of the universe. The Planck mass is given by the values of the Brans--Dicke field, which is coupled to the scalar curvature in the Lagrangian. We first calculate the joint probability distributions of the inflaton and Brans--Dicke fields, in order to compute the 3--volume ratios of homogeneous regions with arbitrary values of the fields still undergoing inflation with respect to thermalized regions. From these volume ratios one is able to extract information on the values of the fields measured by a typical observer for a given potential and, in particular, the typical value of the Planck mass at the end of inflation. In this paper, we investigate volume ratios using a regularization procedure suggested by Vilenkin, and the results are applied to powerlaw and double--well potentials. The spectrum of density fluctuations is calculated for generic potentials, and we discuss the likelihood of various scenarios that could tell us whether our region of the universe is typical or untypical depending on very general bounds on the evolution of the Brans--Dicke field.
Dark energy and dark matter from an inhomogeneous dilaton
Mikel Susperregi
Physics , 2003, DOI: 10.1103/PhysRevD.68.123509
Abstract: A cosmological scenario is proposed where the dark matter (DM) and dark energy (DE) of the universe are two simultaneous manifestations of an inhomogenous dilaton. The equation of state of the field is scale-dependent and pressureless at galactic and larger scales and it has negative pressure as a DE at very large scales. The dilaton drives an inflationary phase followed by a kinetic energy-dominated one, as in the "quintessential inflation" model introduced by Peebles & Vilenkin, and soon after the end of inflation particle production seeds the first inhomogeneities that lead to galaxy formation. The dilaton is trapped near the minimum of the potential where it oscillates like a massive field, and the excess of kinetic energy is dissipated via the mechanism of "gravitational cooling" first introduced by Seidel & Suen. The inhomogeneities therefore behave like solitonic oscillations around the minimum of the potential, known as "oscillatons", that we propose account for most DM in galaxies. Those regions where the dilaton does not transform enough kinetic energy into reheating or carry an excess of it from regions that have cooled, evolve to the tail of the potential as DE, driving the acceleration of the universe.
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