Un estudio sobre el problema de la enseñanza – aprendizaje de la definición geométrica en el nivel medio superior: el efecto de los ejemplos prototipo

Este artículo muestra los resultados de una actividad escolar con estudiantes del Nivel Medio Superior. La actividad se llevó a cabo en el curso de Geometría y Trigonometría. El objetivo principal de esta investigación es hacer una reflexión acerca de las diferencias entre la definición de un concepto y la imagen conceptual que los estudiantes tienen acerca de ese objeto. Así como también analizar las posibles implicaciones que esa diferencia podría generar en el entendimiento de los estudiantes de los conceptos matemáticos.

Label-free based quantitative proteomics analysis of primary neonatal porcine Leydig cells exposed to the persistent contaminant 3-methylsulfonyl-DDE

Evidence that persistent environmental pollutants may target the male reproductive system is increasing. The male reproductive system is regulated by secretion of testosterone by testicular Leydig cells, and perturbation of Leydig cell function may have ultimate consequences. 3-Methylsulfonyl-DDE (3-MeSO₂-DDE) is a potent adrenal toxicants formed from the persistent insecticide DDT. Although studies have revealed the endocrine disruptive effect of 3-MeSO₂-DDE, the underlying mechanisms at cellular level in steroidogenic Leydig cells remains to be established. The current study addresses the effect of 3-MeSO₂-DDE on viability, hormone production and proteome response of primary neonatal porcine Leydig cells. The AlamarBlue™ assay was used to evaluate cell viability. Solid phase radioimmunoassay was used to measure concentration of hormones produced by both unstimulated and Luteinizing hormone (LH)-stimulated Leydig cells following 48h exposure. Protein samples from Leydig cells exposed to a non-cytotoxic concentration of 3-MeSO₂-DDE (10μM) were subjected to nano-LC-MS/MS and analyzed on a Q Exactive mass spectrometer and quantified using label-free quantitative algorithm. Gene Ontology (GO) and Ingenuity Pathway Analysis (IPA) were carried out for functional annotation and identification of protein interaction networks. 3-MeSO₂-DDE regulated Leydig cell steroidogenesis differentially depending on cell culture condition. Whereas its effect on testosterone secretion at basal condition was stimulatory, the effect on LH-stimulated cells was inhibitory. From triplicate experiments, a total of 6804 proteins were identified in which the abundance of 86 proteins in unstimulated Leydig cells and 145 proteins in LH-stimulated Leydig cells was found to be significantly regulated in response to 3-MeSO₂-DDE exposure. These proteins not only are the first reported in relation to 3-MeSO₂-DDE exposure, but also display small number of proteins shared between culture conditions, suggesting the action of 3-MeSO₂-DDE on several targeted pathways, including mitochondrial dysfunction, oxidative phosphorylation, EIF2-signaling, and glutathione-mediated detoxification. Further identification and characterization of these proteins and pathways may build our understanding to the molecular basis of 3-MeSO₂-DDE induced endocrine disruption in Leydig cells.

Jarvis Creek S029

The South Carolina Department of Natural Resources provides maps to recreational and state shellfish grounds, available to the public for recreational harvesting or to commercial harvest. This map shows the location of Jarvis Creek S029 Recreational Shellfish Ground in Beaufort County.

Indenture between William and Margaret Wilson to Stephen M. Jarvis

Indenture of statutory mortgage between William and Margaret Wilson of the Village of Grimsby to Stephen M. Jarvis of Toronto regarding part of Lot no. 10 in the 1st Concession in Grimsby - instrument no. 502, February 26, 1869.

Payment for Shelby, Cunningham, Jarvis, Mater and Jones accounts

Payment for Shelby, Cunningham, Jarvis, Mater and Jones accounts. This document has some water damage which has smeared the writing but it does not affect text, July 29, 1882.

Payment for the Shelby, Cunningham, Jarvis, Jones, Mater, Sampson, Conklin, Dennis and Griffin accounts

Payment for the Shelby, Cunningham, Jarvis, Jones, Mater, Sampson, Conklin, Dennis and Griffin accounts, Jan. 29, 1883.

Payment for the Shelby, Cunningham, Jarvis, Jones, Mater, Sampson, Dennis, Conklin and Griffin accounts

Payment for the Shelby, Cunningham, Jarvis, Jones, Mater, Sampson, Dennis, Conklin and Griffin accounts, July 30, 1883.

Payment for the Cunningham, Jarvis, Jones, Mater, Sampson, Dennis, Conklin and Griffin accounts

Payment for the Cunningham, Jarvis, Jones, Mater, Sampson, Dennis, Conklin and Griffin accounts, Jan. 29, 1884.

Payment for the Atkins and Schmidt accounts from Jarvis, Conklin and Morgan Negotiators of Farm Mortgages

Payment for the Atkins and Schmidt accounts from Jarvis, Conklin and Morgan Negotiators of Farm Mortgages, Dec. 29, 1884.

Form letter: a printed, 2 1/2 page copy of Jarvis Conklin and Co. Mortgage, Loans and Municipal Bonds letter to S.D. Woodruff, signed by James Conklin

Form letter: a printed, 2 1/2 page copy of Jarvis Conklin and Co. Mortgage, Loans and Municipal Bonds letter to S.D. Woodruff, signed by James Conklin, n.d.

Letter which was enclosed with the application, bond mortgage and abstract of the Jones and Mater accounts to Samuel Woodruff from Jarvis, Conklin and Co.

Letter which was enclosed with the application, bond mortgage and abstract of the Jones and Mater accounts to Samuel Woodruff from Jarvis, Conklin and Co., May 4, 1882.

Letter to Jarvis Franklin and Co. from Samuel Woodruff

Letter to Jarvis Franklin and Co. acknowledging the receipts and copies of application from Samuel Woodruff, May 19, 1882.

Letter regarding farm loans addressed to S.D. Woodruff from Jarvis, Conklin and Co.

Letter (1 page, printed) regarding farm loans addressed to S.D. Woodruff from Jarvis, Conklin and Co., Sept. 12, 1882.