Spin dependent D-brane interactions and scattering amplitudes in matrix theory

Spin interactions beteween two moving Dp-branes are analyzed using the Green-Schwarz formalism of boundary states. This approach turns out to be extremely efficient to compute all the spin effects related by supersymmetry to the leading v^4/r^7-p term. All these terms are shown to be scale invariant, supporting a matrix model description of supergravity interactions. By employing the LSZ reduction formula for matrix theory and the mentioned supersymmetric effective potential for D0-branes, we compute the t-pole of graviton-graviton and three form-three form scattering in matrix theory. The results are found to be in complete agreement with tree level supergravity in the corresponding kinematical regime and provide, moreover, an explicit map between these degrees of freedom in both theories.Comment: 8 pages, no figures, talk presented at the conference "Quantum aspects of gauge theories, supergravity and unification", Corfu, Greece, to appear in the proceeding

A robust model for rapidly varying flows over movable bottom with suspended and bedload transport: modelling and numerical approach

We propose a coupled model for suspended and bedload sediment transport in the shallow water framework. The model is deduced under hydrostatic pressure assumptions and will not assume any Bossinesq hypothesis. The numerical resolution is carried out in a segregated way. First the underlying system of conservation laws is solved by using a first order path-conservative Riemann solver. Then, the source terms corresponding with the erosion and depositions rates are approximated in a semi-implicit way. The final scheme preserves the positivity of the density. Several numerical experiments were carried out in order to validate the model and the numerical scheme. The results obtained are in good agreement with the experimental data

Beliefs and understandings of assessment theories and terminologies by university lecturers

This study investigated the beliefs and practices of university lecturers around assessment theories and their links with teaching practices. Given the discrepancies in the literature, the research explored the gap in theoretical understandings of summative and formative assessment and the relationship between them, as well as the relationship with lecturers’ own practices. In total, 109 lecturers from a Colombian institution of higher education participated. An instrument consisting mainly of quantitative questions, with some qualitative questions, which was originally designed to investigate these beliefs and practices among higher education lecturers in England, was used. The translation, validation and reliability processes of the instrument were carried out. Thus, an exploratory factorial study was performed to establish the dimensions of the instrument, determining seven factors. The results indicate discrepancies between what lecturers understand by formative and summative assessment and their practices in the classroom. This coincides with the theoretical contradictions also found in the analysis of specialised literature. It is concluded that a detailed understanding of the discrepancies between beliefs and practices would be valuable in redesigning the ways in which the training of lecturers’ assessment competencies is approached

ANÁLISIS TERRITORIAL MEDIANTE UN MODELO CARTOGRÁFICO EN SAN LUIS HUEXOTLA, TEXCOCO, MÉXICO

During recent decades the change in land occupation has been the result of a process that is derived from the urban growth affecting directly the lands used for agricultural activities. This entails a profound transformation in formerly rural territories and incurs in modifications of phenomena inside them, provoking geographic, economic, political, cultural and environmental changes. The locality of San Luis Huexotla, Texcoco, México, shows fast transformation processes which are not entirely understood in agricultural zones, and constitutes the study area of this study, which was focused in the analysis of change in land use occupation from agricultural to urban in the last twenty years influenced by the process referred through a cartographic model. Digital images were used that provide a geospatial dimension of the territory and constitute an innovating tool for the use of geographic information systems in social studies. In the model, data were incorporated from a broad survey on ejidatarios that contributed to the illustration of the current situation of agricultural production. The results exhibit the strong relationship between the changes in land occupation and socioeconomic factors that have influenced the transformation of the territory and impacted agricultural activities during the period of 1996-2016.En las últimas décadas el cambio de ocupación del suelo ha sido resultado de un proceso que se deriva del crecimiento urbano afectando directamente los suelos utilizados para actividades agrícolas. Lo anterior conlleva una profunda transformación en los territorios otrora rurales e incurre en modificaciones de fenómenos en su interior, provocando cambios geográficos, económicos, políticos, culturales y ambientales. La localidad de San Luis Huexotla, Texcoco, México, registra procesos de transformación rápidos y no totalmente comprendidos en las zonas agrícolas y constituye el área deestudio de esta investigación, la cual se enfocó al análisis del cambio de ocupación del uso de suelo de agrícola a urbano en los últimos veinte años influenciado por el referido proceso mediante un modelo cartográfico. Se utilizaron imágenes digitales que proporcionan una dimensión geo-espacial del territorio y constituyen una herramienta innovadora al uso de sistemas de información geográfica en estudios sociales. En el modelo se incorporaron datos de una amplia encuesta a ejidatarios que aportaron a la ilustración de la situación actual de la producción agrícola. Los resultados exhiben la fuerte relación entre los cambios de ocupación del suelo y factores socioeconómicos que han impactado en la transformación del territorio y modificaron las actividades agrícolas en el periodo 1996-2016

Behavior of tumors under nonstationary theraphy

We present a model for the interaction dynamics of lymphocytes-tumor cells population. This model reproduces all known states for the tumor. Futherly,we develop it taking into account periodical immunotheraphy treatment with cytokines alone. A detailed analysis for the evolution of tumor cells as a function of frecuency and theraphy burden applied for the periodical treatment is carried out. Certain threshold values for the frecuency and applied doses are derived from this analysis. So it seems possible to control and reduce the growth of the tumor. Also, constant values for cytokines doses seems to be a succesful treatment.Comment: 6 pages, 7 figure

Controlled Rate Thermal Analysis (CRTA) as New Method to Control the Specific Surface in Hydroxyapatite Thin Coatings

The control of the texture in synthetic hydroxyapatite ceramics had limited their application in the field of the materials for bone implantation, even more when it is used as a filling in cements and other formulations in orthopedic surgery. The present article shows preliminary results demonstrating the effectiveness of a modification of the controlled rate thermal analysis (CRTA), developed by J. Rouquerol, used for the preparation of ceramic materials with controlled textural characteristics, during the formation of ceramic powders of synthetic hydroxyapatite at low temperatures. The thermal treatments of the hydroxyapatite were carried out in a device connected to a computer, to control temperature and pressure system, keeping the decomposition speed constant. Results, reported when preparing ceramic powders of hydroxyapatite at 300 and 850°C under controlled pressure, using synthetic hydroxyapatite with a Ca/P molar ratio equal to 1.64, were checked using IR spectroscopy and X‐ray diffraction, showed that the formed phase corresponds to that of crystalline hydroxyapatite, even at 300°C of maximum temperature. Values of specific surface (BET) between 17 and 66 m2/g, with pore size in the range of 50–300 Å in both cases are obtained by N2 absorption isotherms, when analyzing the isotherms of nitrogen absorption

How good are the Garvey-Kelson predictions of nuclear masses?

The Garvey-Kelson relations are used in an iterative process to predict nuclear masses in the neighborhood of nuclei with measured masses. Average errors in the predicted masses for the first three iteration shells are smaller than those obtained with the best nuclear mass models. Their quality is comparable with the Audi-Wapstra extrapolations, offering a simple and reproducible procedure for short range mass predictions. A systematic study of the way the error grows as a function of the iteration and the distance to the known masses region, shows that a correlation exists between the error and the residual neutron-proton interaction, produced mainly by the implicit assumption that $V_{np}$ varies smoothly along the nuclear landscape.Comment: 10 pages, 18 figure

Nitrated Fatty-Acids Distribution in Storage Biomolecules during Arabidopsis thaliana Development

The non-enzymatic interaction of polyunsaturated fatty acids with nitric oxide (NO) and de rived species results in the formation of nitrated fatty acids (NO2 -FAs). These signaling molecules can release NO, reversibly esterify with complex lipids, and modulate protein function through the post translational modification called nitroalkylation. To date, NO2 -FAs act as signaling molecules during plant development in plant systems and are involved in defense responses against abiotic stress conditions. In this work, the previously unknown storage biomolecules of NO2 -FAs in Arabidopsis thaliana were identified. In addition, the distribution of NO2 -FAs in storage biomolecules during plant development was determined, with phytosterol esters (SE) and TAGs being reservoir biomolecules in seeds, which were replaced by phospholipids and proteins in the vegetative, generative, and senescence stages. The detected esterified NO2 -FAs were nitro-linolenic acid (NO2 -Ln), nitro-oleic acid (NO2 -OA), and nitro-linoleic acid (NO2 -LA). The last two were detected for the first time in Arabidopsis. The levels of the three NO2 -FAs that were esterified in both lipid and protein storage biomolecules showed a decreasing pattern throughout Arabidopsis development. Esterification of NO2 -FAs in phospholipids and proteins highlights their involvement in both biomembrane dynamics and signaling processes, respectively, during Arabidopsis plant developmentThis research was funded by ERDF grants co-financed by the Spanish Ministry of Economy and Competitiveness (Project PGC2018-096405-B-I00); the Junta de Andalucía (group BIO286); the I+D+I project within the framework Programme of FEDER Andalucía 2014–2020 (Reference 1380901); the grants for I+D+I projects, on a competitive basis, within the scope of the Andalusian plan for research, development and innovation (Junta de Andalucía, PAIDI 2020, Reference: PY20_01002); and the funding for the recruitment of researchers under Action 9 and 10 of the Research Support Plan of the University of Jaén (2019–2020, R.02/10/2020; 2020–2021, R.01/01/2022)