A robust optimization hybrid algorithm for solving the direct kinematics of the general Gough-Stewart platform

El problema de cinemática directa para los robots paralelos se puede enunciar como sigue: dado un conjunto de valores de las variables articulares, se deben encontrar los valores correspondientes en las variables cartesianas, es decir, la posición y orientación del órgano terminal. En muchas ocasiones, el problema de cinemática directa requiere la resolución de un sistema de ecuaciones no-lineales. Los métodos más eficientes para resolver problemas de este tipo suponen convexidad de una función de costo cuyo mínimo es la solución del sistema. La capacidad de tales métodos de optimización para encontrar una solución adecuada depende fuertemente del punto inicial. Un problema bien conocido es la selección de tal punto inicial, el cual requiere información a priori sobre una vecindad convexa donde se encuentra la solución. Este artículo propone un método eficiente para seleccionar y generar el punto inicial basado en aprendizaje probabilístico. El método evita eficientemente los mínimos locales, sin necesidad de intervención humana o información a priori, lo cual lo hace más robusto si se compara con el método Dogleg u otro método de minimización local basado en gradiente. Con el propósito de mostrar el desempeño del método híbrido, se presentan experimentos y su discusión correspondiente. La propuesta se puede extender a otras estructuras con cadenas cinemáticas cerradas, o a la solución en general de sistemas de ecuaciones no-lineales, y por supuesto, para problemas de optimización no-lineales.The direct kinematics problem for parallel robots can be stated as follows: given values of the joint variables, the corresponding Cartesian variable values, the pose of the end-effector, must be found. Most of the times the direct kinematics problem involves the solution of a system of non-linear equations. The most efficient methods to solve such kind of equations assume convexity in a cost function which minimum is the solution of the non-linear system. In consequence, the capacity of such methods depends on the knowledge about an starting point which neighboring region is convex, hence the method can find the global minimum. This article propose a method based on probabilistic learning about an adequate starting point for the Dogleg method which assumes local convexity of the function. The proposed method efficiently avoids the local minima, without need of human intervention or apriori knowledge, thus it shows a more robust performance than the simple Dogleg method or other gradient based methods. To demonstrate the performance of the proposed hybrid method, numerical experiments and the respective discussion are presented. The proposal can be extended to other structures of closed-kinematics chains, to the general solution of systems of non-linear equations, and to the minimization of non-linear functions.Peer Reviewe

The O-mannosylation and production of recombinant APA (45/47 KDa) protein from Mycobacterium tuberculosis in Streptomyces lividans is affected by culture conditions in shake flasks

<p>Abstract</p> <p>Background</p> <p>The Ala-Pro-rich <it>O</it>-glycoprotein known as the 45/47 kDa or APA antigen from <it>Mycobacterium tuberculosis </it>is an immunodominant adhesin restricted to mycobacterium genus and has been proposed as an alternative candidate to generate a new vaccine against tuberculosis or for diagnosis kits. In this work, the recombinant <it>O</it>-glycoprotein APA was produced by the non-pathogenic filamentous bacteria <it>Streptomyces lividans</it>, evaluating three different culture conditions. This strain is known for its ability to produce heterologous proteins in a shorter time compared to <it>M. tuberculosis</it>.</p> <p>Results</p> <p>Three different shake flask geometries were used to provide different shear and oxygenation conditions; and the impact of those conditions on the morphology of <it>S. lividans </it>and the production of rAPA was characterized and evaluated. Small unbranched free filaments and mycelial clumps were found in baffled and coiled shake flasks, but one order of magnitude larger pellets were found in conventional shake flasks. The production of rAPA is around 3 times higher in small mycelia than in larger pellets, most probably due to difficulties in mass transfer inside pellets. Moreover, there are four putative sites of <it>O</it>-mannosylation in native APA, one of which is located at the carboxy-terminal region. The carbohydrate composition of this site was determined for rAPA by mass spectrometry analysis, and was found to contain different glycoforms depending on culture conditions. Up to two mannoses residues were found in cultures carried out in conventional shake flasks, and up to five mannoses residues were determined in coiled and baffled shake flasks.</p> <p>Conclusions</p> <p>The shear and/or oxygenation parameters determine the bacterial morphology, the productivity, and the <it>O</it>-mannosylation of rAPA in <it>S. lividans</it>. As demonstrated here, culture conditions have to be carefully controlled in order to obtain recombinant <it>O</it>-glycosylated proteins with similar "quality" in bacteria, particularly, if the protein activity depends on the glycosylation pattern. Furthermore, it will be an interesting exercise to determine the effect of shear and oxygen in shake flasks, to obtain evidences that may be useful in scaling-up these processes to bioreactors. Another approach will be using lab-scale bioreactors under well-controlled conditions, and study the impact of those on rAPA productivity and quality.</p

Whole sequence of the mitochondrial DNA genome of Kearns Sayre Syndrome patients: Identification of deletions and variants

Mitochondria both produce the energy of the cell as ATP via respiration and regulate cellular metabolism. Accordingly, any deletion or mutation in the mitochondrial DNA (mtDNA) may result in a disease. One of these diseases is Kearns Sayre syndrome (KSS), described for the first time in 1958, where different large-scale deletions of different sizes and at different positions have been reported in the mitochondrial genome of patients with similar clinical symptoms. In this study, sequences of the mitochondrial genome of three patients with clinic features of KSS were analyzed. Our results revealed the position, heteroplasmy percentage, size of deletions, and their haplogroups. Two patients contained deletions reported previously and one patient showed a new deletion not reported previously. These results display for the first time a systematic analysis of mtDNA variants in the whole mtDNA genome of patients with KSS to help to understand their association with the disease

Personalized Medicine in Ovarian Cancer: A Perspective From Mexico

Ovarian cancer (OC) represents a serious health problem worldwide. In Mexico, most OC patients are detected at late stages, consequently making OC one of the leading causes of death in women after reaching puberty. Personalized medicine (PM) provides an individualized therapeutic opportunity for treating each patient relying on “omic” tools to match the correct drug with the specific pathogenic genomic signature. PM can help predict the best therapeutic option for each affected woman suffering from OC. In recent years, Mexico has made contributions to the PM of OC; however, it still has a long way to go for its full implementation in the country’s health system

Las categorías o facetas fundamentales: una metodología para el diseño de taxonomías corporativas de sitios Web argentinos

El análisis por facetas ha sido revaloado en los últimos años para el diseño de taxonomías corporativas. Con el fin de confirmar su utilidad, analizamos los sitios Web de diferentes organizaciones argentinas: tres bodegas de vino, tres industrias alimenticias, seis clubes de fútbol, cinco asociaciones profesionales, tres facultades universitarias y cinco agencias de gobierno. De las 16 categorías o facetas fundamentales propuestas por el Classification Research Group, las bodegas de vino coincidieron en 13 (81%), las industrias alimenticias en 11 (68%), los clubes de fútbol en 7 (43%), las asociaciones profesionales en 5 (31%), las facultades en 8 (50%) y las agencias de gobierno en 9 (56%). Estas diferencias se deben al hecho de que no todas las categorías son necesarias para todas las organizaciones. Se concluye que el método del análisis por facetas es útil para diseñar taxonomías corporativas y optimizar los sitios Web, de acuerdo con las características particulares de cada organización. Palabras claves Análisis de facetas; Taxonomías corporativas; Sítios Web argentinos. Fundamental categories or facets: a methodology for the design of corporate taxonomies of Argentinian web sites Abstract Faceted analysis has been reassessed in last years for designing corporative taxonomies. In order to confirm its usefulness, we analyzed the Web sites of different Argentine organizations: three wineries, three food industries, six football clubs, five professional associations, three university schools, and five government agencies. From the 16 fundamental categories or facets proposed by the Classification Research Group, wineries coincide in 13 (81%), food industries in 11 (68%), football clubs in 7 (43%), professional associations in 5 (31%), university schools in 8 (50%), and government agencies in 9 (56%). These differences are due to the fact that not all the categories are necessary for all organizations. We conclude that the method of faceted analysis is useful for designing corporative taxonomies and for optimizing Web sites, in accordance to particular characteristics of each organization. Keywords Faceted analysis; Corporative taxonomies; Argentine Web sites

Identificación, distribución y plantas hospederas de diez especies de agromyzidae (insecta: diptera), de interés agronómico en México

Ten species of Agromyzidae of agronomic interest in Texcoco, (state of Mexico); Altamira, (state of Tamaulipas), Magdalena Contreras, (Mexico City), and Nativitas, (state of Tlaxcala) are presented. Adescription of the adults, their geographic distributions and their host plants, are provided. In addition a key with photographs of the aedeagus and sperm pumps of all species are provided. The species included are: Amauromyza abnormalis (Malloch), Liriomyza brassicae (Riley), Liriomyza sabaziae Spencer, Liriomyza trifolii (Burgess), Melanagromyza minimoides Spencer, Melanagromyza neotropica Spencer, Melanagromyza splendida Frick, Melanagromyza tomaterae Steyskal, Melanagromyza viridis (Frost) and Ophiomyia lantanae (Froggatt).Se presentan diez especies de Agromyzidae de interés agronómico en Texcoco, (Estado de México), Altamira, (Tamaulipas), Magdalena Contreras, (D. F) y Nativitas, (Tlaxcala). Se proporciona unadescripción del adulto, distribución y plantas hospederas de cada especie, además de una clave para su identificación con fotografías que ilustran las características del edeago y bomba eyaculadora porespecie. Las especies identificadas fueron: Amauromyza abnormalis (Malloch), Liriomyza brassicae (Riley), Liriomyza sabaziae Spencer, Liriomyza trifolii (Burgess), Melanagromyza minimoides Spencer,Melanagromyza neotropica Spencer, Melanagromyza splendida Frick, Melanagromyza tomaterae Steyskal, Melanagromyza viridis (Frost) y Ophiomyia lantanae (Froggatt)

Behavioral and Cytological Differences between Two Parkinson’s Disease Experimental Models

The knowledge about the biochemical and behavioral changes in humans with PD has allowed proposing animal models for its study; however, the results obtained so far have been heterogeneous. Recently, we established a novel PD model in rodents by manganese chloride (MnCl2) and manganese acetate (Mn (OAc)3) mixture inhalation. After inhaling, the rodents presented bilateral loss of SNc dopaminergic neurons. Later, we conclude that the alterations are of dopamine origin since L-DOPA reverted the alterations. After six months, SNc significantly reduced the number of cells, and striatal dopamine content decreased by 71%. The animals had postural instability, action tremor, and akinesia; these symptoms improved with L-DOPA, providing evidence that Mn mixture inhalation induces comparable alterations that those in PD patients. Thus, this study aimed to compare the alterations in two different PD experimental models: 6-OHDA unilateral lesion and Mn mixture inhalation through open field test, rotarod performance and the number of SNc dopaminergic neurons. The results show that the Mn-exposed animals have motor alterations and bilateral and progressive SNc neurons degeneration; in contrast, in the 6-OHDA model, the neuronal loss is unilateral and acute, demonstrating that the Mn exposure model better recreates the characteristics observed in PD patients

Measurement of the semileptonic charge asymmetry in B0 meson mixing with the D0 detector

We present a measurement of the semileptonic mixing asymmetry for B0 mesons, a^d_{sl}, using two independent decay channels: B0 -> mu+D-X, with D- -> K+pi-pi-; and B0 -> mu+D*-X, with D*- -> antiD0 pi-, antiD0 -> K+pi- (and charge conjugate processes). We use a data sample corresponding to 10.4 fb^{-1} of ppbar collisions at sqrt(s) = 1.96 TeV, collected with the D0 experiment at the Fermilab Tevatron collider. We extract the charge asymmetries in these two channels as a function of the visible proper decay length (VPDL) of the B0 meson, correct for detector-related asymmetries using data-driven methods, and account for dilution from charge-symmetric processes using Monte Carlo simulation. The final measurement combines four signal VPDL regions for each channel, yielding a^d_{sl} = [0.68 \pm 0.45 \text{(stat.)} \pm 0.14 \text{(syst.)}]%. This is the single most precise measurement of this parameter, with uncertainties smaller than the current world average of B factory measurements.Comment: Version includes minor textual changes following peer review by journal, most notably the updating of Ref. [21] to reflect the most recent publicatio

Search for new fermions ("quirks") at the Fermilab Tevatron Collider

We report results of a search for particles with anomalously high ionization in events with a high transverse energy jet and large missing transverse energy in $2.4$ fb$^{-1}$ of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron $p\bar{p}$ collider. Production of such particles (quirks) is expected in scenarios with extra QCD-like {\it SU(N)} sectors, and this study is the first dedicated search for such signatures. We find no evidence of a signal and set a lower mass limit of 107 ~GeV for the mass of a charged quirk with strong dynamics scale $\Lambda$ in the range from 10 keV to 1 MeV.Comment: submitted to Phys. Rev. Letter

Evidence for an anomalous like-sign dimuon charge asymmetry

We measure the charge asymmetry A of like-sign dimuon events in 6.1 fb(-1) of p (p) over bar collisions recorded with the D0 detector at a center-of-mass energy root s = 1.96 TeV at the Fermilab Tevatron collider. From A, we extract the like-sign dimuon charge asymmetry in semileptonic b-hadron decays: A(sl)(b) = -0.00957 +/- 0.00251 (stat) +/- 0.00146 (syst). This result differs by 3.2 standard deviations from the standard model prediction A(sl)(b)(SM) = (-2.3(0.6)(+0.5)) x 10(-4) and provides first evidence of anomalous CP violation in the mixing of neutral B mesons