Explorando con los primos, un tema que tiene historia

En el presente trabajo se describen experiencias con números primos en distintos niveles educativos, pasando por el reconocimiento de los números primos, la Criba de Eratóstenes, los primos de Fermat y los polígonos construibles

Impacto de las Tics en los docentes de carreras de Ingeniería

Este trabajo presenta los resultados parciales de una investigación que tiene como objetivo identificar un modelo técnico-pedagógico de educación alternativo aplicando tecnologías de información y comunicación (TIC) que contribuya a reducir los problemas de deserción / fracaso y alargamiento de la duración de los estudios de estudiantes de carreras técnicas de nivel universitario. Se administró una encuesta a los docentes de la facultad de Ingeniería de la Universidad Nacional de Lomas de Zamora y se analizaron las variables: Disponibilidad personal de recursos informáticos, Nivel de conocimientos respecto de las TIC y Aplicación de las TIC a la docencia.Sociedad Argentina de Informática e Investigación Operativ

Refining the role of laparoscopy and laparoscopic ultrasound in the staging of presumed pancreatic head and ampullary tumours

Laparoscopy and laparoscopic ultrasound have been validated previously as staging tools for pancreatic cancer. The aim of this study was to identify if assessment of vascular involvement with abdominal computed tomography (CT) would allow refinement of the selection criteria for laparoscopy and laparoscopic ultrasound (LUS). The details of patients staged with LUS and abdominal CT were obtained from the unit's pancreatic cancer database. A CT grade (O, A-F) of vascular involvement was recorded by a single radiologist. Of 152 patients, who underwent a LUS, 56 (37%) had unresectable disease. Three of 26 (12%) patients with CT grade O, 27 of 88 (31%) patients with CT grade A to D, 17 of 29 (59%) patients with CT grade E and all nine patients with CT grade F were found to have unresectable disease. In all, 24% of patients with tumours <3 cm were found to have unresectable disease. In those patients with tumours considered unresectable, local vascular involvement was found in 56% of patients and vascular involvement with metastatic disease in 17%, while 20% of patients had liver metastases alone and 5% had isolated peritoneal metastases. The remaining patient was deemed unfit for resection. Selective use of laparoscopic ultrasound is indicated in the staging of periampullary tumours with CT grades A to D

Fluorescence laparoscopy imaging of pancreatic tumor progression in an orthotopic mouse model

The use of fluorescent proteins to label tumors is revolutionizing cancer research, enabling imaging of both primary and metastatic lesions, which is important for diagnosis, staging, and therapy. This report describes the use of fluorescence laparoscopy to image green fluorescent protein (GFP)-expressing tumors in an orthotopic mouse model of human pancreatic cancer. The orthotopic mouse model of human pancreatic cancer was established by injecting GFP-expressing MiaPaCa-2 human pancreatic cancer cells into the pancreas of 6-week-old female athymic mice. On postoperative day 14, diagnostic laparoscopy using both white and fluorescent light was performed. A standard laparoscopic system was modified by placing a 480-nm short-pass excitation filter between the light cable and the laparoscope in addition to using a 2-mm-thick emission filter. A camera was used that allowed variable exposure time and gain setting. For mouse laparoscopy, a 3-mm 0° laparoscope was used. The mouse’s abdomen was gently insufflated to 2 mm Hg via a 22-gauge angiocatheter. After laparoscopy, the animals were sacrificed, and the tumors were collected and processed for histologic review. The experiments were performed in triplicate. Fluorescence laparoscopy enabled rapid imaging of the brightly fluorescent tumor in the pancreatic body. Use of the proper filters enabled simultaneous visualization of the tumor and the surrounding structures with minimal autofluorescence. Fluorescence laparoscopy thus allowed exact localization of the tumor, eliminating the need to switch back and forth between white and fluorescence lighting, under which the background usually is so darkened that it is difficult to maintain spatial orientation. The use of fluorescence laparoscopy permits the facile, real-time imaging and localization of tumors labeled with fluorescent proteins. The results described in this report should have important clinical potential

Sequential surgical resection of hepatic and pulmonary metastases from colorectal cancer

# The Author(s) 2010. This article is published with open access at Springerlink.com Background Resection of isolated hepatic or pulmonary metastases from colorectal cancer is widely accepted and associated with a 5-year survival rate of 25–40%. The value of aggressive surgical management in patients with both hepatic and pulmonary metastases still remains a controversial area. Materials and methods A retrospective review of 1,497 patients with colorectal carcinoma (CRC) was analysed. Of 73 patients identified with resection of CRC and, at some point in time, both liver and lung metastases, 17 patients underwent metastasectomy (resection group). The remaining 56 patients comprised the non-resection group. Primary tumour, hepatic and pulmonary metastases of all patients were surgically treated in our department of surgery, and the results are that of a single institution. Results The resection group had a 3-year survival of 77%, a 5-year survival of 55 % and a 10-year survival of 18%; median survival was 98 months. The longest overall survival was 136 months; six patients are still alive. In the resection group, overall survival was significantly higher than in the non-resection group (p&lt;0.01). Independent from the chronology of metastasectomy, 5-year survival was 55 % with respect to the primary resection, 28 % with respect to the first metastasectomy and 14 % with respect t

Life cycles and distribution of atherinids in the marine and estuarine waters of southern Australia

New and published data have been collated for the biology and distribution of atherinid species abundant in the coastal saline waters of Australia below 30°S. This information has been used to determine whether these species typically spawn at sea or pass through the whole of their life cycle in estuaries, and in one case, also lagoons and saline lakes. Length-frequency data, gonadosomatic indices and distribution records indicate that in south-eastern Australia Craterocephalus honoriae and Atherinosoma microstoma typically reach total lengths less than 90 mm, have a one-year life cycle and breed within estuaries. This parallels the situation recently described for Atherinosoma elongata, Atherinosoma wallacei and Allanetta mugiloides in south-western Australia (Prince et al., 1982a; Prince & Potter, 1983). The marine species Atherinosoma presbyteroides, which reaches a similar size and has a one year life cycle in both south-western and south-eastern mainland Australia, only enters estuaries in large numbers in the former region. While Atherinomorus ogilbyi is also found in estuaries and typically breeds at sea, it reaches total lengths as great as 189 mm and has a longer life than A. presbyteroides. The limited data for Atherinason esox and Atherinason hepsetoides demonstrate that both these marine atherinids can attain total lengths of 139 and 108 mm respectively and live for longer than a year but do not enter estuaries in large numbers. The latter species is unique amongst southern Australian atherinids in having a distribution which extends into deeper water. It is suggested that landlocking may have played a role in the evolution and success of the estuarine mode of life sensu stricto of A. wallacei, A. elongata, A. microstoma, A. honoriae and A. mugiloides in southern Australian waters