Measuring Strong and Weak Phases in Time-Independent B Decays

Flavor SU(3) symmetry implies certain relations among $B$-decay amplitudes to $\pi\pi$, $\pi K$ and $K {\bar K}$ final states, when annihilation-like diagrams are neglected. Using three triangle relations, we show how to measure the weak CKM phases $\alpha$ and $\gamma$ using time-independent rate measurements only. In addition, one obtains all the strong final-state phases and the magnitudes of individual terms describing tree (spectator), color-suppressed and penguin diagrams. Many independent measurements of these quantities can be made with this method, which helps to eliminate possible discrete ambiguities and to estimate the size of SU(3)-breaking effects.Comment: 2 figures available from the authors upon request, 12 pages,UdeM-LPN-TH-94-19

Representaciones de los profesores de primarias rurales y urbano-marginadas sobre su trabajo durante el confinamiento por COVID-19

The aim of this research was to analyze the representations of rural and urban-marginalized elementary school teachers about their work during the COVID-19 pandemic at the beginning of the 2020-2021. The theoretical framework that guides the study is the sociodiscursive interactionism applied to the conception of teaching work, particularly the dimensions of represented and prescribed work. Part of the method was to apply a questionnaire with open and multiple-choice items that was supplied to 24 teachers from two Mexican states: San Luis Potosí and Veracruz. The results exibit that distance learning increases educational backwardness or hinders learning. Furthermore, they allow to identify the difficulties foreseen for the new school year (Internet connection, explanation of content and communication with families) and recognize that WhatsApp became the main alternative for the development of synchronous classes, sending assignments and communication with students and their familie

Estimating wind speed and capacity factors in Mexico using reanalysis data

In the fundamental stage of resource assessment, high-quality wind speed measurements are required to estimate power production. However, this high-quality data is not always available, and therefore the analysis of alternative sources becomes essential. In this work, we analyze the ability of MERRA-2 to represent wind speed characteristics at 24 anemometric stations in Mexico. The assessment was carried out using the Pearson correlation coefficient between the observed time series, and the obtained by interpolating bias-corrected reanalysis-estimated wind speed to all locations for different time-averaging periods. Results showed that the reanalysis’ performance is not uniform throughout the country; it depends on the time resolution, local orographic conditions, and the relationship between the local flow and the large-scale circulation. Based on these results, the country was subdivided into eight regions. The best-represented region was the Chivela Pass, where the winds are tightly linked to the interaction between the large-scale circulation and the local orography. The worst performing regions were located where the land sea-mask and orography at the reanalysis’ resolution may not be accurate enough to reproduce the station’s wind speeds. Reanalysis-estimated capacity factors exhibit large interannual variability in some stations, which can have significant consequences for the operation of individual wind farms and the power grid. The results show that, while caution should be exercised when applying reanalyses to wind resource assessment in Mexico, reanalysis wind power estimates can be a valuable tool to investigate the feasibility and installed capacity requirements for Mexico to meet its renewable energy targets

Cervical cancer cell lines expressing NKG2D-ligands are able to down-modulate the NKG2D receptor on NKL cells with functional implications

<p>Abstract</p> <p>Background</p> <p>Cervical cancer represents the third most commonly diagnosed cancer and the fourth leading cause of cancer-related deaths in women worldwide. Natural killer (NK) cells play an important role in the defense against viruses, intracellular bacteria and tumors. NKG2D, an activating receptor on NK cells, recognizes MHC class I chain-related molecules, such as MICA/B and members of the ULBP/RAET1 family. Tumor-derived soluble NKG2D-ligands have been shown to down-modulate the expression of NKG2D on NK cells. In addition to the down-modulation induced by soluble NKG2D-ligands, it has recently been described that persistent cell-cell contact can also down-modulate NKG2D expression. The goal of this study was to determine whether the NKG2D receptor is down-modulated by cell-cell contact with cervical cancer cells and whether this down-modulation might be associated with changes in NK cell activity.</p> <p>Results</p> <p>We demonstrate that NKG2D expressed on NKL cells is down-modulated by direct cell contact with cervical cancer cell lines HeLa, SiHa, and C33A, but not with non-tumorigenic keratinocytes (HaCaT). Moreover, this down-modulation had functional implications. We found expression of NKG2D-ligands in all cervical cancer cell lines, but the patterns of ligand distribution were different in each cell line. Cervical cancer cell lines co-cultured with NKL cells or fresh NK cells induced a marked diminution of NKG2D expression on NKL cells. Additionally, the cytotoxic activity of NKL cells against K562 targets was compromised after co-culture with HeLa and SiHa cells, while co-culture with C33A increased the cytotoxic activity of the NKL cells.</p> <p>Conclusions</p> <p>Our results suggest that differential expression of NKG2D-ligands in cervical cancer cell lines might be associated with the down-modulation of NKG2D, as well as with changes in the cytotoxic activity of NKL cells after cell-cell contact with the tumor cells.</p

Future Scenarios and Trends of Energy Demand in Colombia using Long-range Energy Alternative Planning

The prospective of Colombia's energy demand will be defined by economic, social, cultural and political phenomena. Modeling the factors that determine demand can be broadly divided into quantitative and qualitative. The quantitative phenomena, demography, energy efficiency and the direct consumption of fuels; qualitative effects are specific conditions, which are defined within each scenario as variables that will have effects on quantitative phenomena. In the baseline scenario, the transportation sector is expected to remain as the largest representative of Colombia's energy demand, although its participation in the year 2050 will be reduced by approximately 7%. The residential sector will have a reduced growth supported by the law 1715 that will increase distributed generation and implement more efficient lighting systems. A scenario focused on energy diversification shows a reduction in demand since the short term. Transport sector is maintained with similar behaviors in all scenarios as the goods transport networks keep the same.  Keywords: Energy Prospective, Energy Demand, Economic & Energy.  JEL Classifications: Q47, Q41, Q5