A generalization of the Lomnitz logarithmic creep law via Hadamard fractional calculus

We present a new approach based on linear integro-differential operators with logarithmic kernel related to the Hadamard fractional calculus in order to generalize, by a parameter $\nu \in (0,1]$, the logarithmic creep law known in rheology as Lomnitz law (obtained for $\nu=1$). We derive the constitutive stress-strain relation of this generalized model in a form that couples memory effects and time-varying viscosity. Then, based on the hereditary theory of linear viscoelasticity, we also derive the corresponding relaxation function by solving numerically a Volterra integral equation of the second kind. So doing we provide a full characterization of the new model both in creep and in relaxation representation, where the slow varying functions of logarithmic type play a fundamental role as required in processes of ultra slow kinetics.Comment: 15 pages, 2 figures, to appear in Chaos, Solitons and Fractals (2017

Morphological diversity among local and introduced maize (Zea mays L.) varieties in Haiti for yield improvement

Maize, the cereal with the largest production in the world, is a staple crop in many developing countries includingHaiti. Even if Haiti is the second maize consumer in the Caribbean region, its national yield is low and alleged ofaflatoxin contamination. In order to increase grain yield, three introduced and two local maize varieties (theseused as comparative control) were evaluated. Three field trials were carried out at Torbeck and Morne Briller (Port-Salut) during different growing seasons. Experiments were designed in a three-replicate randomized block. Eachexperimental plot was 3.50 m per 10.5 m with a gross area of 36.75 m2 and 40 000 plants/ha densities. The trialswere carried out according to local agricultural practices. The results revealed that the introduced varieties hada smaller yield than the local ones. Moreover, all varieties showed some aflatoxin content below the EuropeanUnion limit (5μg/Kg). Statistical analyses showed a strong and direct correlation between yield and ear weightand an inverse correlation between yield and male and female flowering day after sowing. The broad phenotypicdiversity suggested a rich reserve of alleles to exploit in a breeding program focused to improve food security inHaiti

Characterization of NK cells in mouse models of systemic lupus erythematosus and of the role of the p85β pi3k subunit in NKG2D signaling in NK cells

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología Molecular. Fecha de lectura: 22-11-2013Natural killer (NK) cells are large granular lymphocytes that play an important part as a link between the innate and adaptive immune systems. Various autoimmune diseases are correlated with alterations in the activity of NK cells; nonetheless, their role in the pathogenesis of systemic lupus erythematosus (SLE), a complex multi-factorial disease, has not been extensively studied. One of the most important activating NK cell receptors is NKG2D, which is able to signal via the p85 subunit (either the α or β subunit) of the PI3K (phosphatidylinositide 3-kinase) enzyme, to which it binds indirectly via the DAP10 adaptor molecule. It is not known which of the two p85 subunits binds preferentially to DAP10, or whether the p85β subunit participates in mediating NKG2D receptor signaling. In the first part of this work, we studied the role of NK cells in murine models of SLE. We show that the MRL/MpJ mouse is a useful model for this analysis, and that NK cells in diseased mouse spleen suffer from impaired differentiation, which is site-specific. In addition, we show that NK cells in the kidneys of diseased SLE-like mice are phenotypically more mature and more active compared to those of healthy mice and in other non-target organs. We report the expression of the NKG2D ligands Rae-1 and Mult-1 specifically in the glomeruli of various lupus-prone mouse models. Expression of these ligands increases concomitantly with disease state and influences NK cell maturation and IFN-γ production. For the second section of the study, we analyzed the PI3K p85β subunit function in NK cells. We demonstrate that p85β is not involved in NK cell differentiation, proliferation, or maturation. The p85β-deficient NK cell phenotype is more activated than that of control mouse NK cells, as seen via cytotoxicity assays and cytokine secretion. We found that this activated phenotype is probably due to the role of p85β in NKG2D internalization, which is impaired in as p85β-deficient NK cells. Our findings identify an undescribed NK cell function in SLE pathogenesis and of the p85β PI3K subunit in the regulation of the NKG2D receptor function.Las células “asesinas naturales” (NK) son linfocitos que sirven como enlace entre el sistema inmune adaptativo e innato. Alteraciones en la actividad en las células NK están correlacionadas con enfermedades autoinmunes, aunque el papel de estas células en el Lupus Sistémico Eritromatoso (SLE), una enfermedad compleja y multifactorial, aún sigue siendo controvertido. Uno de los receptores de activación mas importantes en las células NK es el receptor NKG2D. NKG2D se une a la molécula adaptadora DAP10, y señaliza a través de la subunidad p85 del enzima PI3K. Aún no se sabe cual de las dos subunidades de p85 se une preferiblemente a la molécula adaptadora DAP10, ni si la subunidad p85β tiene un papel en la señalización mediada por el receptor NKG2D. En la primera parte de este trabajo, hemos estudiado el papel de las células NK en modelos murinos de SLE. Demostramos que el modelo MRL/MpJ es un modelo válido para el estudio de células NK en SLE, y que las células NK en el bazo de ratones enfermos tienen defectos en diferenciación. Demostramos también que células NK en los riñones de ratones enfermos con SLE son fenotipicamente más maduras y más activas comparadas con las células NK de ratones sanos, y con las células NK presentes en órganos no afectados por la enfermedad. Además, reportamos la expresión de los ligandos de NKG2D Rae-1 y Mult-1 específicamente en los glomérulos de varios ratones con susceptibilidad genética a desarrollar SLE. La expresión de estos ligandos aumenta con la progresión de la enfermedad, y que la expresión de estos ligandos influye en la maduración y producción de IFN-γ por parte de células NK. En la segunda parte de este trabajo hemos estudiado el papel de la subunidad p85β en células NK. Demostramos que la subunidad p85β no está involucrada en la diferenciación, proliferación, o maduración de células NK. Sin embargo, mostramos cómo las células NK de ratones deficientes de p85β tienen un fenotipo mas activado, como se demuenstra mediante ensayos de citotoxicidad y secreción de citoquinas. Este fenotipo más activo podría deberse al papel que p85β juega en la internalización de NKG2D, dado que las células NK deficientes en p85β tienen defectos en la internalización de dicho receptor. Estos resultados indican un papel nuevo para las células NK en la patogénesis de SLE y de la subunidad p85β de PI3K en la regulación de las funciones del receptor NKG2D

Photodetectors fabricated from a self-assembly of a deoxyguanosine derivative

A metal–semiconductor–metal (MSM) photodetector has been fabricated using as the semiconductor, a self-assembled layer of a DNA basis, namely a deoxyguanosine derivative, deposited between two gold electrodes. These were defined lithographically on a SiO2 substrate, separated by a distance of about 120 nm. The resulting self-assembled guanosine crystal has been deposited in such a way to achieve striking semiconducting properties. We show that with these conditions, the I–V characteristics are independent of the crystal orientation. The device shows a high current response (differential resistance at room temperature ranges in MΩ) which is symmetric with respect to bias sign and dependent on the illumination conditions. This behavior can be explained by taking into account the standard MSM theory and its applications as a photodetector

Intraspecific phenotypic variability of plant functional traits in contrasting mountain grasslands habitats

Empirical studies that link plants intraspecific variation to environmental conditions are almost lacking, despite their relevance in understanding mechanisms of plant adaptation, in predicting the outcome of environmental change and in conservation. Here, we investigate intraspecific trait variation of four grassland species along with abiotic environmental variation at high spatial resolution (n = 30 samples per species trait and environmental factor per site) in two contrasting grassland habitats in Central Apennines (Italy). We test for phenotypic adaptation between habitats, intraspecific trait-environment relationships within habitats, and the extent of trait and environmental variation. We considered whole plant, clonal, leaf, and seed traits. Differences between habitats were tested using ANOVA and ANCOVA. Trait-environment relationships were assessed using multiple regression models and hierarchical variance partitioning. The extent of variation was calculated using the coefficient of variation. Significant intraspecific differences in trait attributes between the contrasting habitats indicate phenotypic adaptation to in situ environmental conditions. Within habitats, light, soil temperature, and the availability of nitrate, ammonium, magnesium and potassium were the most important factors driving intraspecific trait-environment relationships. Leaf traits and height growth show lower variability than environment being probably more regulated by plants than clonal traits which show much higher variability. We show the adaptive significance of key plant traits leading to intraspecific adaptation of strategies providing insights for conservation of extant grassland communities. We argue that protecting habitats with considerable medium- and small-scale environmental heterogeneity is important to maintain large intraspecific variability within local populations that finally can buffer against uncertainty of future climate and land use scenarios

Thermochemistry and kinetics of the trans-N2H2+N reaction

AbstractThermochemical and kinetics properties of the hydrogen abstraction and addition processes of the trans-N2H2+N reaction were computed using high-level ab initio and DFT approximation methods with aug-cc-pVXZ (X=T,Q) basis set. The CCSD (T)/CBS//BB1K/aug-cc-pVTZ results for classical barrier height are 13.1 and 15.0kcal/mol for the abstraction and addition reactions, respectively. The thermal rate constants were calculated using the dual-level direct dynamics by variational transition state theory with the BB1K potential energy surface and thermochemical properties corrected with the CCSD (T)/CBS//BB1K/aug-cc-pVTZ results. The rate constants calculated show that the variational and tunneling effects play a relevant role only for the abstraction reaction

Transversal Study Describing the Applicability of the Conicity Index in the Age Group of Children

O excesso de massa corporal predominantemente na região abdominal do corpo favorece o surgimento de várias doenças, dentre elas as dislipidemias e os distúrbios cardiovasculares. Nesse contexto, o índice de conicidade (IC) é uma alternativa viável para indicar obesidade abdominal. O objetivo deste estudo foi verificar se o índice de massa corporal (IMC) e o IC apresentam alguma correlação e se o IC das crianças pode ser inserido na faixa de corte, utilizando sua fórmula original. Tratou-se de uma metodologia quantitativa analítica e descritiva, com delineamento transversal. Crianças de ambos os sexos entre 9 e 11 anos de idade participaram deste estudo. A circunferência da cintura-CC (m), altura (m) e índice de massa corporal (kg) foram utilizados como variáveis ​​para o cálculo do IC e IMC. Após a coleta dessas variáveis, foi realizada a tabulação, e posteriormente, o software estatístico SAS® Studio foi utilizado para realizar as análises estatísticas. Sessenta e seis crianças (27 homens e 39 mulheres) foram avaliadas. Observou-se que os dados de IC e IMC não se correlacionam. No entanto, os valores obtidos pelo cálculo do intervalo de confiança de 95% da média das crianças estão contidos no intervalo 1,00 e 1,73

Transistors based on the Guanosine molecule (a DNA base)

Abstract Molecules are attractive to develop nano-electronic devices. In this paper a new type of transistor is realized by using self-organized films of the Guanosine molecule, a modified DNA base. With its 40 nm channel length the transistor is a good starting point for a new class of nano-electronics devices. Experimental current-voltage characteristics are shown. A circuital model is also proposed