Exposición de curvas y superficies: una experiencia extraacadémica universitaria

En este artículo se comenta una experiencia extraacadémica realizada por un grupo de alumnos universitarios de Matemáticas, juntamente con su profesor, en el marco de la Semana de las Matemáticas organizada por la Facultad de Matemáticas de Sevilla para conmemorar el Año Mundial de las Matemáticas (Año 2000). La citada experiencia consistió en la realización y montaje de una Exposición de Curvas y Superficies, cuyos objetivos generales, desarrollo y conclusiones finales constituyen la base de este trabajo

Internal friction associated with ε martensite in shape memory steels produced by casting route and through additive manufacturing: Influence of thermal cycling on the martensitic transformation

Among the different families of shape memory alloys (SMA), the Fe-Mn-Si-Cr-Ni alloys have attracted a renewed interest because of its low cost, high corrosion resistance and high recovery strength during the shape memory effect, and the new technologies of additive manufacturing offer unforeseen possibilities for this family of SMA. In the present work, the reversible gamma - epsilon martensitic transformation (MT), responsible for the shape memory effect, is studied in two Fe-Mn-Si-Cr-Ni alloys with high (20.2 wt%) and low (15.8 wt%) Mn content, produced by the conventional route of casting and rolling, in comparison with the MT in another similar alloy, with intermediate Mn content (19.4 wt%), which was produced by gas atomization and additive manufacturing through laser metal deposition. The forward and reverse gamma - epsilon MT is studied by mechanical spectroscopy through the internal friction spectra and the dynamic modulus variation, together with a parallel microstructural characterization including in-situ observation of the gamma - epsilon MT during cooling and heating at the scanning electron microscope. The evolution of the transformed fraction of epsilon martensite, evaluated through the integral area of the internal friction peak, was followed along thermal cycling in all three alloys. Both, the internal friction and the electron microscopy studies show that the epsilon martensite amount increases very fast during the first few cycles, and then decreases with a tendency towards its stabilization for many tens of cycles. The results show that the gamma - epsilon MT is more stable on cycling in the additive manufactured sample than in the conventionally processed samples, opening new avenues for designing shape memory steels to be specifically processed through additive manufacturing.This work was supported by the ELKARTEK-CEMAP (KK-2020/00047) project from the Industry Department of the Basque Government, and the GIU-17/071 from the University of the Basque Country, UPV/EHU. This work made use of the SGIKER facilities at the UPV/EHU

Polymorphisms of the WNT10B Gene, Bone Mineral Density, and Fractures in Postmenopausal Women

Producción CientíficaWnt ligands are important regulators of skeletal homeostasis. Wnt10B tends to stimulate the differentiation of common mesenchymal precursors toward the osteoblastic lineage, while inhibiting adipocytic differentiation. Hence, we decided to explore the association of WNT10B allelic variants with bone mineral density and osteoporotic fractures. A set of tag SNPs capturing most common variations of the WNT10B gene was genotyped in 1438 Caucasian postmenopausal women, including 146 with vertebral fractures and 432 with hip fractures. We found no association between single SNPs and spine or hip bone mineral density (BMD). In the multilocus analysis, some haplotypes showed a slight association with spine BMD (P = 0.03), but it was not significant after multiple-test correction. There was no association between genotype and vertebral or hip fractures. Transcripts of WNT10B and other Wnt ligands were detected in human bone samples by real-time PCR. However, there was no relationship between genotype and RNA abundance. Thus, WNT10B is expressed in the bone microenvironment and may be an important regulator of osteoblastogenesis, but we have not found evidence for a robust association of common WNT10B gene allelic variants with either BMD or fractures in postmenopausal women

Differential analysis of genome-wide methylation and gene expression in mesenchymal stemcells of patients with fractures and osteoarthritis

Insufficient activity of the bone-forming osteoblasts leads to low bone mass and predisposes to fragility fractures. The functional capacity of human mesenchymal stem cells (hMSCs), the precursors of osteoblasts, may be compromised in elderly individuals, in relation with the epigenetic changes associated with aging. However, the role of hMSCs in the pathogenesis of osteoporosis is still unclear. Therefore, we aimed to characterize the genome-wide methylation and gene expression signatures and the differentiation capacity of hMSCs from patients with hip fractures. We obtained hMSCs from the femoral heads of women undergoing hip replacement due to hip fractures and controls with hip osteoarthritis. DNA methylation was explored with the Infinium 450K bead array. Transcriptome analysis was done by RNA sequencing. The genomic analyses revealed that most differentially methylated loci were situated in genomic regions with enhancer activity, distant from gene bodies and promoters. These regions were associated with differentially expressed genes enriched in pathways related to hMSC growth and osteoblast differentiation. hMSCs from patients with fractures showed enhanced proliferation and upregulation of the osteogenic drivers RUNX2/OSX. Also, they showed some signs of accelerated methylation aging. When cultured in osteogenic medium, hMSCs from patients with fractures showed an impaired differentiation capacity, with reduced alkaline phosphatase activity and poor accumulation of a mineralized matrix. Our results point to 2 areas of potential interest for discovering new therapeutic targets for low bone mass disorders and bone regeneration: the mechanisms stimulating MSCs proliferation after fracture and those impairing their terminal differentiation

Contribution of genetic and epigenetic mechanisms to Wnt pathway activity in prevalent skeletal disorders

Producción CientíficaWe reported previously that the expression of Wnt-related genes is lower in osteoporotic hip fractures than in 26 osteoarthritis. We aimed to confirm those results by analyzing β-catenin levels and explored potential genetic 27 and epigenetic mechanisms involved. 28 β-Catenin gene expression and nuclear levelswere analyzed by real time PCR and confocal immunofluorescence. 29 Increased nuclear β-catenin was found in osteoblasts isolated from patients with osteoarthritis (99 ± 4 30 units vs. 76 ± 12, p = 0.01, n = 10), without differences in gene transcription, which is consistent with 31 a post-translational down-regulation of β-catenin and decreased Wnt pathway activity. 32 Twenty four single nucleotide polymorphisms (SNPs) of genes showing differential expression between fractures 33 and osteoarthritis (WNT4, WNT10A, WNT16 and SFRP1) were analyzed in DNA isolated from blood of 853 pa- 34 tients. The genotypic frequencies were similar in both groups of patients, with no significant differences. 35 Methylation ofWnt pathway genes was analyzed in bone tissue samples (15 with fractures and 15 with osteo- 36 arthritis) by interrogating a CpG-based methylation array. Six genes showed significant methylation differences 37 between both groups of patients: FZD10, TBL1X, CSNK1E, WNT8A, CSNK1A1L and SFRP4. The DNA demethylating 38 agent 5-deoxycytidine up-regulated 8 genes, including FZD10, in an osteoblast-like cell line, whereas it down- 39 regulated other 16 genes. 40 In conclusion,Wnt activity is reduced in patientswith hip fractures, in comparisonwith thosewith osteoarthritis. 41 It does not appear to be related to differences in the allele frequencies of the Wnt genes studied. On the other 42 hand, methylation differences between both groups could contribute to explain the differences inWnt activit

Evaluación del estado nutricional en pacientes trasplantados renales durante 5 años de seguimiento

Introducción: El aumento de peso y la malnutrición después del trasplante renal es frecuente, y el sobrepeso y la obesidad resultante se asocia con complicaciones graves de salud. Por el contrario, la prevalencia de la desnutrición en pacientes con trasplante renal y sus efectos en el resultado del trasplante de riñón se subestima. Objetivos: El objetivo de este trabajo fue evaluar el estado nutricional de pacientes trasplantados renales y determinar si en el periodo de cinco años de seguimiento, estos pacientes sufren alteraciones que sugieran deterioro nutricional. Métodos: La muestras estuvo formada por 119 pacientes trasplantados renales, que asistieron durante cinco años a la consulta postrasplante. A todos los pacientes se realizaron determinaciones de colesterol total, lipoproteínas de baja densidad (LDL), lipoproteínas de alta densidad (HDL), concentraciones de triglicéridos y ferritina (Ft), y se les efectuaron mediciones antropométricas de peso, altura e IMC. Los pacientes fueron divididos en tres grupos según la tasa de filtración glomerular : Grupo 1: < 60 mL/min, Grupo 2: 89–60 mL/min Grupo 3: ≥ 90 mL/min. Resultados: El peso e IMC tiende a disminuir en el grupo 3 mientras aumenta en el resto de grupos. Se produce una disminución de Colesterol total, HDL, LDL, Trigliceridos y Ferritina menos acusado en el grupo 3. Conclusiones: Tras cinco años se puede observar una reducción significativa de los parametros bioquímicos nutricionales en general, así mismo el estado nutricional esta estrechamente relacionado y es directamente proporcional a la función del injerto.Introduction: Weight gain and malnutrition after kidney transplantation is common and the resulting overweight and obesity is associated with serious health complications. By contrast, the prevalence of malnutrition in patients with renal transplantation and its impact on the outcome of kidney transplantation is underestimated. Objectives: The aim of this study was to evaluate the nutritional status of renal transplant patients and determine if the five-year follow-up, these patients undergo alterations that suggest nutritional deterioration. Methods: The sample consisted of 119 renal transplant patients who attended for five years post-transplant consultation. All patients measurements of total cholesterol, low density lipoprotein (LDL), high density lipoprotein (HDL), triglycerides and ferritin (Ft) were performed. and anthropometric measurements were made of weight, height and BMI. Patients were divided into three groups according to GFR Group 1: <60 mL / min, Group 2: 89-60 mL / min Group 3: ≥ 90 mL / min. Results: The weight and BMI tended to decrease in group 3 while increasing in the other groups. A decrease in total cholesterol, HDL, LDL, Triglycerides and Ferritin less pronounced in group 3 occurs. Conclusions: After five years you can see a significant reduction in nutritional biochemical parameters in general, likewise the nutritional status is closely related, and is directly proportional to the function of the graft

BIOSTIMULATION OF CUCUMBER CROP PRODUCED IN SHELTERED CONDITIONS

Objective: To evaluate the physiological and productive response of cucumber crop to the induction of three commercial phytohormones (Cito Xplosión, Súper Hormonal, Vitaminum Forte) grown under protected conditions. Design/methodology/approach: The experiment consisted of three treatments, T1 (Cito Xplosión), T2 (Súper Hormonal), and T3 (Vitaminum Forte). The evaluated variables were plant height, number of leaves, fresh biomass, fruit diameter and length, number and weight, total soluble solids, pH, and electrical conductivity. Results: In the physiological variables, values of plant heights were 225, 228, 220, and 238 cm for T1, T2, T3, and the control. 33 leaves for all treatments and 31 for the control, T1 and T2 produced higher fresh biomass in leaves, stems, roots, and flowers, while T3 produced higher biomass in fruits. For the fruit length, the values were 16.9, 17.6, 17.6, and 18.4 cm, and diameters of 5.2, 5.2, 5.1, and 5.1 cm for T1, T2, T3, and the control. The weight of fruits was 293.2, 297.3, 283.9, and 281.7 g with yields of 10.1, 10.9, 10.0, and 9.6 kg m-2 for T1, T2, T3, and the control. Limitations on study/implications: More varieties should be evaluated using different nutrient solution concentrations and management practices as a function of the number of stems to assess whether phytohormones influence physiological or productive variables. Findings/conclusions: From an economic point of view, T2 was the best treatment, achieving a higher yield and fruit quality

OCCASO - II. Physical parameters and Fe abundances of red clump stars in 18 open clusters

Open clusters have long been used to study the chemodynamical evolution of the Galactic disc. This requires a homogeneously analysed sample covering a wide range of ages and distances. In this paper, we present the Open Clusters Chemical Abundances from Spanish Observatories (OCCASO) second data release. This comprises a sample of high-resolution (R > 65 000) and high signal-to-noise spectra of 115 red clump stars in 18 open clusters. We derive atmospheric parameters (Teff, log g, ξ), and [Fe/H] abundances using two analysis techniques: equivalent widths and spectral synthesis. A detailed comparison and a critical review of the results of the two methods are made. Both methods are carefully tested between them, with the Gaia FGK benchmark stars, and with an extensive sample of literature values. We perform a membership study using radial velocities and the resulting abundances. Finally, we compare our results with a chemodynamical model of the Milky Way thin disc concluding that the oldest open clusters are consistent with the models only when dynamical effects are taken into account