Mining-energy public policy of lithium in Mexico: tension between nationalism and globalism

This article addresses Mexico's present situation in the lithium industry and its near future, ceteris paribus. Mexico's short- and long-term lithium supply will not improve by the exploration and exploitation planned by the nationalistic objectives of the current government. This analysis demonstrates that significant changes must be made to Mexico's energy policy to promote the development of lithium due to five risks: manufacturing capacity, misaligned incentives, industrial policies, geographic concentration, and limited international coordination. Therefore, although the world's largest lithium mine was found in Sonora in 2019, Mexico's policy approaches to nationalize lithium exploration and exploitation will not allow the country to capitalize on the boom of this industry, as happened in Bolivia. In the short term, Mexico's policies will create an exploration deficit due to the country's lack of know-how and investment. Thus, Mexico will not extract lithium in the long term nor benefit from the demand increase and development of a value chain, especially in North America. Given these risks, this article postulates that Mexico's lithium policy should be revised to open its market to foreign investment and use this nascent market to a good advantage

Travelling waves in a nonlinear degenerate diffusion model for bacterial pattern formation

We study a reaction diffusion model recently proposed in [5] to describe the spatiotemporal evolution of the bacterium Bacillus subtilis on agar plates containing nutrient. An interesting mathematical feature of the model, which is a coupled pair of partial differential equations, is that the bacterial density satisfies a degenerate nonlinear diffusion equation. It was shown numerically that this model can exhibit quasi-one-dimensional constant speed travelling wave solutions. We present an analytic study of the existence and uniqueness problem for constant speed travelling wave solutions. We find that such solutions exist only for speeds greater than some threshold speed giving minimum speed waves which have a sharp profile. For speeds greater than this minimum speed the waves are smooth. We also characterise the dependence of the wave profile on the decay of the front of the initial perturbation in bacterial density. An investigation of the partial differential equation problem establishes,via a global existence and uniqueness argument, that these waves are the only long time solutions supported by the problem. Numerical solutions of the partial differential equation problem are presented and they confirm the results of the analysis

Superiorization: An optimization heuristic for medical physics

Purpose: To describe and mathematically validate the superiorization methodology, which is a recently-developed heuristic approach to optimization, and to discuss its applicability to medical physics problem formulations that specify the desired solution (of physically given or otherwise obtained constraints) by an optimization criterion. Methods: The underlying idea is that many iterative algorithms for finding such a solution are perturbation resilient in the sense that, even if certain kinds of changes are made at the end of each iterative step, the algorithm still produces a constraints-compatible solution. This property is exploited by using permitted changes to steer the algorithm to a solution that is not only constraints-compatible, but is also desirable according to a specified optimization criterion. The approach is very general, it is applicable to many iterative procedures and optimization criteria used in medical physics. Results: The main practical contribution is a procedure for automatically producing from any given iterative algorithm its superiorized version, which will supply solutions that are superior according to a given optimization criterion. It is shown that if the original iterative algorithm satisfies certain mathematical conditions, then the output of its superiorized version is guaranteed to be as constraints-compatible as the output of the original algorithm, but it is superior to the latter according to the optimization criterion. This intuitive description is made precise in the paper and the stated claims are rigorously proved. Superiorization is illustrated on simulated computerized tomography data of a head cross-section and, in spite of its generality, superiorization is shown to be competitive to an optimization algorithm that is specifically designed to minimize total variation.Comment: Accepted for publication in: Medical Physic

PARÁMETROS INMUNOLÓGICOS EN OVINOS DE PELO PARA ABASTO CONTRA NEMATODOS GASTROINTESTINALES EN TABASCO, MÉXICO

A study was carried out in a sheep slaughterhouse in Tabasco, México, to determine immunological parameters in sheep, through blood, saliva, feces and mucous samples from small intestine and rennet of n=60. The cell agglomerate volume (VCA), plasma protein (PP), and leukocyte differential count were determined. The number of nematode eggs per gram (HPG) was obtained from feces, and adult parasites from rennet and small intestine were counted. The level of immunoglobulin A (IgA) was determined against Haemonchus contortus and Trichostrongylus colubriformis, and the correlations between variables were estimated. The sheep that had the highest number of adult nematodes (534) presented greater elimination of eggs (2401 to 12501 HPG). The average VCA and PP were higher, 34.5% and 7.6 g dL-1, respectively, in sheep that had been stabled compared to those in grazing, 32.3% and 7.1 g dL-1, respectively. The highest counts of lymphocytes and peripheral eosinophils (7812 and 124, respectively) were present in grazing sheep. The VCA was higher, 36.9 %, in those animals that were free from nematodes and lower in those with parasites (31.1%). The activity of the IgA was higher in rennet mucous, 1.33±0.92, and correlated significantly with IgA in serum. Because of the variability of sheep for supply, the IgA from mucous and eosinophils had scarce relation to the parasitological and hematological parametersSe realizó un estudio en un rastro de ovinos en Tabasco, México para determinar parámetros inmunológicos en ovinos, mediante muestras de sangre, saliva, heces y mucosa de intestino delgado y abomaso de n=60. Se determinó el volumen celular aglomerado (VCA), proteína plasmática (PP) y conteo diferencial de leucocitos. A partir de las heces se obtuvo el número de huevos de nematodos por gramo (HPG) y contabilizaron parásitos adultos de abomaso e intestino delgado. Se determinó el nivel de inmunoglobulina A (IgA) contra Haemonchus contortus y Trichostrongylus colubriformis, y estimaron correlaciones entre las variables. Los borregos que tuvieron la mayor cantidad de nematodos adultos (534), presentaron mayor eliminación de huevos de (2401 a 12501 HPG). Los promedios del VCA y PP fueron mayores, 34.5% y 7.6 g dL-1, respectivamente, en ovinos que se habían estabulado en comparación con aquellos en pastoreo, 32.3% y 7.1 g dL-1 respectivamente. Los mayores conteos de linfocitos y eosinófilos periféricos (7812 y 124 respectivamente) ocurrieron en los ovinos en pastoreo. El VCA fue mayor, 36.9%, en aquellos animales que estaban libres de nematodos y menor en los parasitados (31.1%). La actividad de la IgA fue mayor en mucosa de abomaso, 1.33±0.92 y correlacionó de manera significativa con la IgA en suero. Por la variabilidad de los ovinos para abasto, los IgA de mucosa y eosinófilos tuvieron poca relación con los parámetros parasitológicos y hematológico

Ultraviolet-A Light and Riboflavin Therapy for Acanthamoeba Keratitis: A Case Report

Purpose: To report ultraviolet-A (UV-A) light treatment in a patient with Acanthamoeba keratitis (AK). Methods: Interventional case report. A standard protocol for ultraviolet corneal therapy, with a power emission of 3 mW/cm2 and a wavelength of 370 nm, was used. The protocol included an 8-nm bandwidth at a 54-mm distance measured with a collimation system of diodes as well as a protective shield of riboflavin in a case of documented AK. Results: A 54-year-old female patient with AK, showing no therapeutic response to a wide variety of topical antimicrobial agents and with a visual acuity of 20/400, was treated with UV-A therapy. The patient displayed a favourable response in the first 24 h after treatment, with improvement of symptoms, visual acuity (to 20/200) and biomicroscopy cornea with haze degree I. By the third week post-treatment, the patient was symptom-free. Her visual acuity was 20/30, and the affected cornea was clear. Five months after treatment, there had been no recurrence, and her vision was 20/20. Conclusions: Treatment with UV-A light was an effective therapy in this case of AK

The relationship between truncation and phosphorylation at the C-terminus of tau protein in the paired helical filaments of Alzheimer's disease

Acknowledgements: Authors want to express their gratitude to Dr. P. Davies (Albert Einstein College of Medicine, Bronx, NY, USA) and Lester I. Binder (NorthWestern, Chicago, IL, USA) for the generous gift of mAbs (TG-3, Alz-50, and MC1), and (TauC-3), respectively, and to M. en C. Ivan J. Galván-Mendoza for his support in confocal microscopy, and Ms. Maricarmen De Lorenz for her secretarial assistance. We also want to express our gratitude to the Mexican Families who donate the brain of their loved ones affected with Alzheimer's disease, and made possible our research. This work was financially supported by CONACyT grant, No. 142293 (For R.M).Peer reviewedPublisher PD

Utilizacion del infiltrometro con doble desague en surcos para la determinacion de las curvas de infiltracion.

En base a las consideraciones anteriores al propósito a esta investigación es presentar un método de determinación de la velocidad de infiltración, modificado del infiltrômetro de Surco, (boers y Millar, 1974), que analizado a través de procedimientos muy simplificados, puede proporcionar una base firme para mejorar las determinaciones de las pruebas de infiltración a nivel de predios o granjas.bitstream/item/132728/1/32523.pd

Immune Responses to RHAMM in Patients with Acute Myeloid Leukemia after Chemotherapy and Allogeneic Stem Cell Transplantation

Leukemic blasts overexpress immunogenic antigens, so-called leukemia-associated antigens like the receptor for hyaluronan acid-mediated motility (RHAMM). Persistent RHAMM expression and decreasing CD8+ T-cell responses to RHAMM in the framework of allogeneic stem cell transplantation or chemotherapy alone might indicate the immune escape of leukemia cells. In the present study, we analyzed the expression of RHAMM in 48 patients suffering from acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Furthermore, we correlated transcripts with the clinical course of the disease before and after treatment. Real-time quantitative reverse transcriptase polymerase chain reaction was performed from RNA of peripheral blood mononuclear cells. T cell responses against RHAMM were assessed by tetramer staining (flow cytometry) and enzyme-linked immunospot (ELISPOT) assays. Results were correlated with the clinical outcome of patients. The results of the present study showed that almost 60% of the patients were RHAMM positive; specific T-cells recognizing RHAMM could be detected, but they were nonfunctional in terms of interferon gamma or granzyme B release as demonstrated by ELISPOT assays. Immunotherapies like peptide vaccination or adoptive transfer of RHAMM-specific T cells might improve the immune response and the outcome of AML/MDS patients

The Speed of Fronts of the Reaction Diffusion Equation

We study the speed of propagation of fronts for the scalar reaction-diffusion equation $u_t = u_{xx} + f(u)$\, with $f(0) = f(1) = 0$. We give a new integral variational principle for the speed of the fronts joining the state $u=1$ to $u=0$. No assumptions are made on the reaction term $f(u)$ other than those needed to guarantee the existence of the front. Therefore our results apply to the classical case $f > 0$ in $(0,1)$, to the bistable case and to cases in which $f$ has more than one internal zero in $(0,1)$.Comment: 7 pages Revtex, 1 figure not include