3,586 research outputs found
Genetic relationships within and among Iberian fescues (Festuca L.) based on PCR-amplified markers
The genus Festuca comprises approximately 450 species and is widely distributed around the world. The Iberian Penninsula, with more than 100 taxa colonizing very diverse habitats, is one of its main centers of diversification. This study was conducted to assess molecular genetic variation and genetic relatedness among 91 populations of 31 taxa of Iberian fescues, based on several molecular markers (random amplified polymorphic DNA, amplified fragment length polymorphisms, and trnL sequences). The analyses showed the paraphyletic origin of the broad-leaved (subgenus Festuca, sections Scariosae and Subbulbosae, and subgenus Schedonorus) and the fine-leaved fescues (subgenus Festuca, sections Aulaxyper, Eskia, and Festuca). Schedonorus showed a weak relationship with Lolium rigidum and appeared to be the most recent of the broad-leaved clade. Section Eskia was the most ancient and Festuca the most recent of the fine-leaved clade. Festuca and Aulaxyper were the most related sections, in concordance with their taxonomic affinities. All taxa grouped into their sections, except F. ampla and F. capillifolia (section Festuca), which appeared to be more closely related to Aulaxyper and to a new independent section, respectively. Most populations clustered at the species level, but some subspecies and varieties mixed their populations. This study demonstrated the value in combining different molecular markers to uncover hidden genetic relationships between populations of Festuca
Identification and characterization of Rhipicephalus (Boophilus) microplus candidate protective antigens for the control of cattle tick infestations
The cattle ticks, Rhipicephalus (Boophilus) spp., affect cattle production in tropical and subtropical regions of the world. Tick vaccines constitute a cost-effective and environmentally friendly alternative to tick control. The recombinant Rhipicephalus microplus Bm86 antigen has been shown to protect cattle against tick infestations. However, variable efficacy of Bm86-based vaccines against geographic tick strains has encouraged the research for additional tick-protective antigens. Herein, we describe the analysis of R. microplus glutathione-S transferase, ubiquitin (UBQ), selenoprotein W, elongation factor-1 alpha, and subolesin (SUB) complementary DNAs (cDNAs) by RNA interference (RNAi) in R. microplus and Rhipicephalus annulatus. Candidate protective antigens were selected for vaccination experiments based on the effect of gene knockdown on tick mortality, feeding, and fertility. Two cDNA clones encoding for UBQ and SUB were used for cattle vaccination and infestation with R. microplus and R. annulatus. Control groups were immunized with recombinant Bm86 or adjuvant/saline. The highest vaccine efficacy for the control of tick infestations was obtained for Bm86. Although with low immunogenic response, the results with the SUB vaccine encourage further investigations on the use of recombinant subolesin alone or in combination with other antigens for the control of cattle tick infestations. The UBQ peptide showed low immunogenicity, and the results of the vaccination trial were inconclusive to assess the protective efficacy of this antigen. These experiments showed that RNAi could be used for the selection of candidate tick-protective antigens. However, vaccination trials are necessary to evaluate the effect of recombinant antigens in the control of tick infestations, a process that requires efficient recombinant protein production and formulation systems
Undergraduate student gender, personality and academic confidence
Within a socio-situational and socio-behavioural context, the relationships between the Big
Five personality traits and the academic confidence of university students and how they differed
by sex of the student was explored. Previous research has identified both conscientiousness and
academic confidence as being linked to university performance. In respect of sex, female students
have been found to score higher on all of the Big Five measures, whereas the relationship between sex
and academic confidence has been mixed. Using self-report measures of personality and academic
confidence from 1523 Spanish students, it was found that the female students were more confident in
their grades, studying and attendance components of academic confidence and had higher scores
for conscientiousness, agreeableness and neuroticism personality measures. A multiple regression
analysis found that personality predicts academic confidence, with conscientiousness being the trait
that statistically loaded the most strongly. This research further confirms the validity of the Academic
Behavioural Confidence scale and suggests that measures of personality and, especially, academic
confidence could be usefully used in student support situations to help students acquire the strategies
and skills that lead to successful university study. It is suggested that further research in the area
needs to include outcome or achievement measures and measures of hypothetical constructs, such as
personality and academic confidence, that go beyond self-report measures
Non-linear dynamic soil response underneath a vertical breakwater subjected to impulsive sea wave actions
A theoretical model of the soil-water-structure interaction involved in a breakwater
structure subjected to sea wave actions is presented. The model includes i) soil skeleton-pore fluid
interaction governed by the u − pw Generalized Biot formulation [1] including dynamic effects, ii)
non-linear soil elastoplastic behaviour described by a novel Generalized Plasticity model [2] coupled
with a conservative hyperelastic formulation for the dependence of the elastic stiffness on the stress
[3], iii) coupling between the caisson and foundation through a non-linear contact with geometrical
compatible formulation incorporating frictional behaviour.
The numerical solution of the settled governing equations has been fully developed through the Finite
Element Method. Furthermore, a program called ADÍNDICA has been created in M Matlab language.
ADÍNDICA is a Spanish acronym for “Caisson Breakwater Dynamic Analysis”. Related numerical
analyses are developed with reference to precise boundary value problems of specific physical nature.
ADÍNDICA code has been able to reproduce adequately the principal characteristics of the caisson
oscillations and instantaneous pore pressure generation relation deduced experimentally. Moreover,
ADÍNDICA has been able to reproduce satisfactorily the accumulative settlement behaviour of a
vertical breakwater structure subjected to series of sea wave impacts including the correlation
between accumulated settlements and residual pore pressure
Dislocation Emission around Nanoindentations on a (001) fcc Metal Surface Studied by STM and Atomistic Simulations
We present a combined study by Scanning Tunneling Microscopy and atomistic
simulations of the emission of dissociated dislocation loops by nanoindentation
on a (001) fcc surface. The latter consist of two stacking-fault ribbons
bounded by Shockley partials and a stair-rod dislocation. These dissociated
loops, which intersect the surface, are shown to originate from loops of
interstitial character emitted along the directions and are usually
located at hundreds of angstroms away from the indentation point. Simulations
reproduce the nucleation and glide of these dislocation loops.Comment: 10 pages, 4 figure
Molecular identification of Cordylobia anthropophaga Blanchard (Diptera: Calliphoridae) larvae collected from dogs (Canis familiaris) in Jos South, Plateau State, Nigeria
This work is licensed under the
Creative Commons Attribution License.-- et al.Myiasis-causing larvae were extracted from dogs attending veterinary clinics in Plateau State, Nigeria and subjected to molecular analysis involving polymerase chain reaction amplification of the 28S rRNA gene of blowflies, cloning and sequencing techniques. All larvae were confirmed as Cordylobia anthropophaga Blanchard (Diptera: Calliphoridae) after the initial morphological identification. This is the first molecular identification of any myiasis-causing fly species in Nigeria and may serve as a reliable alternative to morphological identification where samples are not well preserved or difficult to identify to species level.We thank at the Instituto de Investigacion en Recursos Cinegiticos, IREC (CSIC-UCLM-JCCM), Ciudad Real, Spain for providing the facilities to carry out this research.Peer Reviewe
Secuenciación dinámica de sistemas de fabricación flexible mediante aprendizaje automático: análisis de los principales sistemas de secuenciación existentes
Una forma habitual de secuenciar de modo dinámico los trabajos en los sistemas de fabricación es mediante el empleo de reglas de secuenciación. Sin embargo, el problema que presenta este método es que el comportamiento del sistema de fabricación dependerá de su estado, y no existe una regla que supere a las demás en todos los posibles estados que puede presentar el sistema de fabricación. Por lo tanto, sería interesante usar en cada momento la regla más adecuada. Para lograr este objetivo, se pueden utilizar sistemas de secuenciación que emplean aprendizaje automático que permiten, analizando el comportamiento previo del sistema de fabricación (ejemplos de entrenamiento), obtener el conocimiento necesario para determinar la regla de secuenciación más apropiada en cada instante. En el presente trabajo se realiza una revisión de los principales sistemas de secuenciación existentes en la literatura que utilizan aprendizaje automático para variar de forma dinámica la regla de secuenciación empleada en cada momento
Trajectory Tracking Error Using Fractional Order PID Control Law for Two‐Link Robot Manipulator via Fractional Adaptive Neural Networks
The problem of trajectory tracking of unknown nonlinear systems of fractional order is solved using fractional order dynamical neural networks. For this purpose, we obtained control laws and laws of adaptive weights online, obtained using the Lyapunov stability analysis methodology of fractional order. Numerical simulations illustrate the obtained theoretical results
Aplicación de redes neuronales artificiales a la previsión de series temporales no estacionarias o no invertibles
En los últimos tiempos se ha comprobado un aumento del interés en la aplicación de las Redes Neuronales Artificiales a la previsión de series temporales, intentando explotar las indudables ventajas de estas herramientas. En este artículo se calculan previsiones de series no estacionarias o no invertibles, que presentan dificultades cuando se intentan pronosticar utilizando la metodología ARIMA de Box-Jenkins. Las ventajas de la aplicación de redes neuronales se aprecian con más claridad, cuando se trata de pronosticar sistemas multivariantes no estacionarios
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