418 research outputs found

    Reinstatement of rhipicephalus (Boophilus) australis (Acari: Ixodidae) with redescription of the adult and larval stages

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    Rhipicephalus australis Fuller, the Australian cattle tick, is reinstated and the adults and larvae redescribed from material collected in Australia. This long ignored boophilid was previously known as R. microplus Canestrini for specimens reported in Australia and New Caledonia. The adults of R. australis are easily recognized by a combination of characters, such as the ventro-medial spurs in the palpal segments of the male, and the abundant, plumose, pale white setae on the dorsum of the female. Other details, such as coxal and adanal shields are more variable among different populations and may lead to incorrect determinations. Larvae of R. australis are clearly smaller than those of R. microplus. The use of principal components analysis on body measurements leads to a clear separation of larvae of both taxa. A phylogenetic analysis based on 12S- and 16S-rDNA gene sequences supports the conspecificity of the neotype material on which the reinstatement of the species is proposed, and of the specimens used for previous interspecific crosses. R. australis is now known to be present in Australia, New Caledonia, the island of Borneo, Philippines, Sumatra, Java, New Guinea, Cambodia, and Tahiti. Both R. microplus and R. australis coexist in some countries in southeastern Asia. Given the extreme importance of these ticks for the cattle industry, field data on their distribution in the region are required to know the actual range of these species and to understand the evolution of the group.Fil: Estrada Peña, Agustín. Universidad de Zaragoza; EspañaFil: Venzal, José M.. Universidad de la República; UruguayFil: Nava, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; ArgentinaFil: Mangold, Atilio Jose. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Guglielmone, Alberto Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; ArgentinaFil: Labruna, Marcelo B.. Universidade de Sao Paulo; BrasilFil: de la Fuente, José. Instituto de Investigación en Recursos Cinegéticos; Españ

    Trust in Leadership and Perceptions of Justice in Fostering Employee Commitment

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    In a period of uncertainty, trust in leadership and perceptions of fairness have emerged as pivotal factors for fostering employee identification and affective commitment. Drawing from authentic leadership theory, this leadership style is identified as a crucial antecedent of affective commitment, examining the mediating role of distributive justice and the moderating role of interactional justice. A quantitative approach was employed, utilizing data from 302 questionnaires completed by Spanish retail workers. For data analysis, SPSS v.25 was used to generate descriptive statistics, while partial least squares structural equation modeling was applied to test the proposed hypotheses. Our findings revealed that authentic leadership is positively associated with the development of affective commitment, with distributive justice acting as a mediating factor between the two. Furthermore, interactional justice negatively moderates the relationship between distributive justice and affective commitment. Contrary to initial expectations, the second moderation, between authentic leadership and affective commitment, was not found to be significant

    Vectorial model for progressive adaptation for purchase and sale of shares using stock market indicators

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    Las acciones son consideradas como parte fundamental del mercado de renta variable, ya que sus valores cambian con el tiempo como consecuencia de la oferta y la demanda, y por efecto de la volatilidad de los mercados. Esta volatilidad hace que la negociación de acciones en un mercado bursátil sea una tarea extremadamente difícil. Es por esto que en este artículo se desarrolla y analiza un sistema para la negociación automática de acciones, el cual incorpora una serie de modelos vectoriales por aprendizaje progresivo inspirado en la estructura de una máquina de vector soporte. Para la configuración de la estructura general del modelo, se utilizaron una serie de indicadores bursátiles utilizados por los inversionistas para fijar posiciones de compra y venta, mientras que el aprendizaje el modelo utilizó una estrategia negociación secuencial sobre cinco acciones diferentes inscritas en la bolsa de valores de Colombia, y en donde el aprendizaje estuvo guiado por las posiciones de compra y venta que iban fijando cada uno de los indicadores bursátiles de entrada, Los resultados arrojados por el sistema, mostraron la rentabilidad que el modelo iba logrando en la negociación como consecuencia del avance en el aprendizaje que cada uno de los modelos iba logrando a lo largo de la secuencia de acciones utilizadas para este estudio, haciendo el sistema cada vez más robusto, lo que lo hace ideal para la negociación de acciones basada en indicadores bursátilesThe shares are considered as a fundamental part of the equity market, as their values change over time as a result of offer and demand, and the effect of market volatility. This volatility makes the trading of shares on a stock exchange is an extremely difficult task. That is why in this article develops and analyzes a system for automatic trading shares, which incorporates a series of progressive learning vector models inspired by the structure of a support vector machine. For the configuration of the overall structure of the model, a number of stock market indicators used by investors to establish positions for buying and selling, were used while learning the model used a sequential negotiation strategy on five different shares listed on the stock exchange of Colombia, and where learning was guided by buying and selling positions that were setting each input stock market indicators. Results from the system showed the profitability that the model was achieved in the negotiation as a result of progress in learning that each of the models was achieved along the sequence of actions used for this study, making the system each more robust time, which makes it ideal for trading shares based on stock indexe

    Singular Temperatures Connected to Charge Transport Mechanism Transitions in Perylene Bisimides from Steady-State Photocurrent Measurements

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    Perylene bisimides (PBIs) are n-type semiconducting and photogenerating materials widely used in a variety of optoelectronic devices. Particularly interesting are PBIs that are simultaneously water-soluble and liquid-crystalline (PBI-W+LC) and, thus, attractive for the development of high-performing easily processable applications in biology and “green” organic electronics. In this work, singular temperatures connected to charge transport mechanism transitions in a PBI-W+LC derivative are determined with high accuracy by means of temperature-dependent photocurrent studies. These singular temperatures include not only the ones observed at 60 and 110 °C, corresponding to phase transition temperatures from crystalline to liquid-crystalline (LC) and from LC to the isotropic phase, respectively, as confirmed by differential scanning calorimetry (DSC), but also a transition at 45 °C, not observed by DSC. By analyzing the photocurrent dependence simultaneously on temperature and on light intensity, this transition is interpreted as a change from monomolecular to bimolecular recombination. These results might be useful for other semiconducting photogenerating materials, not necessarily PBIs or even organic semiconductors, which also show transport behavior changes at singular temperatures not connected with structural or phase transitions.We appreciate support from the Spanish government (MINECO) and the European Community (FEDER) through Grant MAT-2011-28167-C02-01, as well as the University of Alicante. We gratefully acknowledge financial support from MINECO (MAT2014-52305-P) and the UCM-BSCH joint project (GR3/14-910759). A. de la Peña thanks Universidad Complutense for a predoctoral fellowship

    Functional and Immunological Relevance of Anaplasma marginale Major Surface Protein 1a Sequence and Structural Analysis.

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    Bovine anaplasmosis is caused by cattle infection with the tick-borne bacterium, Anaplasma marginale. The major surface protein 1a (MSP1a) has been used as a genetic marker for identifying A. marginale strains based on N-terminal tandem repeats and a 5'-UTR microsatellite located in the msp1a gene. The MSP1a tandem repeats contain immune relevant elements and functional domains that bind to bovine erythrocytes and tick cells, thus providing information about the evolution of host-pathogen and vector-pathogen interactions. Here we propose one nomenclature for A. marginale strain classification based on MSP1a. All tandem repeats among A. marginale strains were classified and the amino acid variability/frequency in each position was determined. The sequence variation at immunodominant B cell epitopes was determined and the secondary (2D) structure of the tandem repeats was modeled. A total of 224 different strains of A. marginale were classified, showing 11 genotypes based on the 5'-UTR microsatellite and 193 different tandem repeats with high amino acid variability per position. Our results showed phylogenetic correlation between MSP1a sequence, secondary structure, B-cell epitope composition and tick transmissibility of A. marginale strains. The analysis of MSP1a sequences provides relevant information about the biology of A. marginale to design vaccines with a cross-protective capacity based on MSP1a B-cell epitopes

    Molecular dynamics simulation of surface phenomena due to high electronic excitation ion irradiation in amorphous silica

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    We studied by means of an atomistic model based on molecular dynamics the thermal evolution of surface atoms in amorphous silica under high electronic excitation produced by irradiation with swift heavy ions. The model was validated with the total and differential yields measured in sputtering experiments with different ions and ion energies showing a very good quantitative prediction capability. Three mechanisms are behind the evolution of the surface region: (1) an ejection mechanism of atoms and clusters with kinetic energy exceeding their binding energy to the sample surface, which explains the experimentally observed angular distributions of emitted atoms, and the correlation of the total sputtering yield with the electronic stopping power and the incidence angle. (2) A collective mechanism of the atoms in the ion track originated by the initial atom motion outwards the track region subsequently followed by the return to the resulting low-density region in the track center. The collective mechanism describes the energy dissipation of bulk atoms and the changes in density, residual stress, defect formation and optical properties. (3) A flow mechanism resulting from the accumulation and subsequent evolution of surface atoms unable to escape. This mechanism is responsible for the crater rim formation.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was funded by the projects Radiafus-5 (PID2019-105325RB-C32) of Spanish Ministry of Science, Technofusion (S2018/EMT-4437) of Madrid Regional Government and Eurofusion (EH150531176). The authors acknowledge the computer resources and technical assistance provided by the Centro de Supercomputación y Visualización de Madrid (CeSViMa) CESVIMA-MAGERIT. AP acknowledges the support of FONDECYT under grants 3190123. EMB thanks support from grant ANPCyT PICTO-UUMM-2019-00048. JK was supported by the Beatriz Galindo Program (BEAGAL18/00130) from the Ministerio de Educación y Formación Profesional of Spain

    Microwave-induced covalent functionalization of few-layer graphene with arynes under solvent-free conditions

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    A non-conventional modification of exfoliated few-layer graphene (FLG) with different arynes under microwave (MW) irradiation and solvent-free conditions is reported. The described approach allows reaching fast, efficient and mild covalent functionalization of FLG.M. P. is the recipient of the AXA Chair (2016-2023). This work was supported by the EU H2020-Adhoc-2014-20 Graphene Core1 (no. 696656)S

    Structural basis of human kinesin-8 function and inhibition

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    Kinesin motors play diverse roles in mitosis and are targets for anti-mitotic drugs. The clinical significance of these motors emphasizes the importance of understanding the molecular basis of their function. Equally, investigations into the modes of inhibition of these motors provide crucial information about their molecular mechanisms. Kif18A regulates spindle microtubules through its dual functionality – microtubule-based stepping and regulation of microtubule dynamics. We investigated the mechanism of Kif18A and its inhibition by the small molecule BTB-1. The Kif18A motor domain drives ATP-dependent plus-end microtubule gliding, and undergoes conformational changes consistent with canonical mechanisms of plus-end directed motility. The Kif18A motor domain also depolymerises microtubule plus and minus ends. BTB-1 inhibits both microtubule-based Kif18A activities. A reconstruction of BTB-1-bound, microtubule-bound Kif18A, in combination with computational modelling, identified an allosteric BTB-1 binding site near loop5, where it blocks the ATP-dependent conformational changes we characterised. Strikingly, BTB-1 binding is close to that of well-characterised Kif11 inhibitors that block tight microtubule binding, whereas BTB-1 traps Kif18A on the microtubule. Our work highlights a general mechanism of kinesin inhibition in which small molecule binding near loop5 prevents a range of conformational changes, blocking motor function
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