Mechanism of G1 arrest in the Drosophila eye imaginal disc.

RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.BACKGROUND: Most differentiating cells are arrested in G1-phase of the cell cycle and this proliferative quiescence appears important to allow differentiation programmes to be executed. An example occurs in the Drosophila eye imaginal disc, where all cells are synchronized and arrested in G1 phase prior to making a fate choice either to initiate the first round of photoreceptor differentiation or to re-enter one terminal mitosis. RESULTS: We have analysed the mechanism of this temporally regulated G1-phase in order to develop an integrated model of this proliferative regulation. We find that an overlapping set of cell cycle inhibitors combine to form an efficient barrier to cell cycle progression. This barrier depends on both the primary secreted signals that drive retinal development, Dpp and Hh. Each of these has distinct, as well as partially overlapping functions, in ensuring that Cyclin E and dE2F1 are kept in check. Additionally, inhibition of Cyclin A by Roughex is essential, and this regulation is independent of Dpp and Hh. CONCLUSION: One implication of these results is to further support the idea that Cyclin A has important functions in S-phase entry as well as in mitosis. The unexpectedly complex network of regulation may reflect the importance of cells being uniformly ready to respond to the inductive signals that coordinate retinal differentiation.Published versio

Interacción entre iguales y aprendizaje de conceptos científicos

Throughout this article we try to present the first results of a wider research about the verbal intercourses which take place in small groups of students, and its relationship with the process of learning scientific concepts. The research has been done with secondary students, aged 15-16. They were working in real context on the solution of activities leading to the development of their alternative conceptions about energy. Here you have some of the conclusions obtained: 1) Their development towards more accurate concepts is wider when working in groups than working individually. 2) The actions of giving and receiving help and the following usage of that help have a clear and significative relationship with the fact of learning. 3) The pupils in homogeneous groups interact and learn more than those pupils in heterogeneous groups. Previous training in cooperative skills helps those students with less experience

Topological Progression in Proliferating Epithelia Is Driven by a Unique Variation in Polygon Distribution

Morphogenesis is consequence of lots of small coordinated variations that occur during development. In proliferating stages, tissue growth is coupled to changes in shape and organization. A number of studies have analyzed the topological properties of proliferating epithelia using the Drosophila wing disc as a model. These works are based in the existence of a fixed distribution of these epithelial cells according to their number of sides. Cell division, cell rearrangements or a combination of both mechanisms have been proposed to be responsible for this polygonal assembling. Here, we have used different system biology methods to compare images from two close proliferative stages that present high morphological similarity. This approach enables us to search for traces of epithelial organization. First, we show that geometrical and network characteristics of individual cells are mainly dependent on their number of sides. Second, we find a significant divergence between the distribution of polygons in epithelia from mid-third instar larva versus early prepupa. We show that this alteration propagates into changes in epithelial organization. Remarkably, only the variation in polygon distribution driven by morphogenesis leads to progression in epithelial organization. In addition, we identify the relevant features that characterize these rearrangements. Our results reveal signs of epithelial homogenization during the growing phase, before the planar cell polarity pathway leads to the hexagonal packing of the epithelium during pupal stages.LME is supported by the Miguel Servet (Instituto Carlos III) program that also funded the work. LME and DSG are funded by the Spanish Ministry of Science (BFU2011-25734). AS is funded by the Consejería de Innovación, Ciencia y Empresa of the Junta de Andalucía.Peer Reviewe

A Multiinstitutional Spanish Master’s Program in Ecosystem Restoration: Vision and Four-Year Experience

Since 2006, an innovative, multiinstitutional Spanish Master in Ecosystem Restoration (MER) is jointly offered by four major public universities in Madrid. In view of the high student demand—about 900 applications this academic year for only 30 places, a remarkable 75% rate of professional poststudy employment in a period of economic crisis, and the high number (> 40) of prestigious organizations involved in the program, we consider the MER program, although still young, to be very promising for the long term. We explain the process to create the MER and achieve the results obtained thus far. We describe its organization, report its vital statistics in terms of students, and identify some strengths and weaknesses observed to date. The MER program has evolved as a network of knowledge and experience that links universities, lecturers, researchers, students, private and public companies, NGOs, and administration centers. Our aim is to help other groups that may want to launch similar graduate-level ecological restoration degree programs

Rapid Prototyping for Evaluating Vehicular Communications

[Abstract] This Thesis details the different elements of a rapid prototyping system able to implement and evaluate vehicular communications fast, according to the continuously evolving requirements of the industry. The system is basically composed of a testbed and a channel emulator, which allow evaluating communication transceivers in realistic vehicular scenarios. Two different testbeds are introduced: a generic 2x2 system and a vehicular platform. The former is used to compare and study space-time block coding (STBC) transmissions at 2.4 GHz over different indoor channels. The latter makes use of software transceivers whose performance is evaluated when they work under artificial high-speed Rayleigh-fading scenarios. To show the capabilities of both platforms, three software transceivers have been developed following the specifications for the physical layers of the standards IEEE 802.11p, IEEE 802.11a and IEEE 802.16e (Mobile WiMAX). The present work details the different elements that make up each transceiver and indicates how to connect them to the rest of the system to perform evaluation measurements. Finally, single-antenna and multi-antenna performances are measured thanks to the design and implementation of three FPGA-based channel emulators that are able to recreate up to seven different vehicular scenarios that include urban canyons, suburban areas and highways[Resumo] A presente Tese detalla os elementos necesarios para constituir un sistema basado en prototipado rápido capaz de levar a cabo e avaliar comunicacións vehiculares. O hardware do sistema está composto básicamente por unha plataforma de probas (testbed) e un emulador de canal, os cales permiten avaliar o rendemento de transceptores inartiamicos recreando diferentes escenarios vehiculares. Inicialmente, este traballo céntrase na descripción do hardware do sistema, detallando a construcción e proba dunha plataforma multi-antena e un testebed vehicular. Estos sistemas permitiron, respectivamente, estudar o comportamento de códigos STBC (space-time block codes) en interiores e medir o rendemento de tranceptores software ao traballar a distintas velocidades vehiculares en canais con desvaecemento Rayleigh. Tres transceptores software foron creados seguindo as especificacións das capas físicas dos estándares IEEE 802.11p, IEEE 802.11a e IEEE 802.16e (Mobile WiMAX). Este traballo detalla os diferentes componentes de cada transceptor, indicando cómo conectalos ao resto do sistema para realizar a avaliacition do seu rendemento. Dita avaliación realizouse coa axuda de tres emuladores de canal basados en tecnoloxía FPGA (Field Programmable Gate Array), os cales son capaces de recrear ata sete escenarios vehiculares distintos, incluindo cañóns urbanos, zonas suburbanas e autopistas.[Resumen] La presente Tesis detalla los elementos necesarios para constituir un sistema basado en prototipado rtiapido capaz de llevar a cabo y evaluar comunicaciones vehiculares. El hardware del sistema está compuesto por una plataforma de pruebas (testbed) y un emulador de canal, los cuales permiten evaluar el rendimiento de transceptores inaltiambricos recreando diferentes escenarios vehiculares. Inicialmente, este trabajo se centra en la descripcition del hardware del sistema, detallando la construccition y prueba de una plataforma multi-antena y un testebed vehicular. Estos sistemas han permitido, respectivamente, estudiar el comportamiento de ctiodigos STBC (space-time block codes) en interiores y medir el rendimiento en canal con desvanecimiento Rayleigh de tranceptores software a distintas velocidades vehiculares. Tres transceptores software han sido creados siguiendo las especificaciones de las capas físicas de los estandares IEEE 802.11p, IEEE 802.11a e IEEE 802.16e (Mobile WiMAX). Este trabajo detalla los diferentes componentes de cada transceptor, indicando ctiomo conectarlos al resto del sistema para realizar la evaluacition de su rendimiento. Dicha evaluacition se realiztio con la ayuda de tres emuladores de canal basados en FPGAs (Field Programmable Gate Array), los cuales son capaces de recrear comunicaciones multi-antena en hasta siete escenarios vehiculares distintos, incluyendo cañones urbanos, zonas suburbanas y autopistas

Age-Mediated Transcriptomic Changes in Adult Mouse Substantia Nigra

Substantia nigra pars compacta (SNpc) is highly sensitive to normal aging and selectively degenerates in Parkinson's disease (PD). Until now, molecular mechanisms behind SNpc aging have not been fully investigated using high throughput techniques. Here, we show early signs of aging in SNpc, which are more evident than in ventral tegmental area (VTA), a region adjacent to SNpc but less affected in PD. Aging-associated early changes in transcriptome were investigated comparing late middle-aged (18 months old) to young (2 months old) mice in both SNpc and VTA. A meta-analysis of published microarray studies allowed us to generate a common >transcriptional signature> of the aged (≥ 24 months old) mouse brain. SNpc of late-middle aged mice shared characteristics with the transcriptional signature, suggesting an accelerated aging in SNpc. Age-dependent changes in gene expression specific to SNpc were also observed, which were related to neuronal functions and inflammation. Future studies could greatly help determine the contribution of these changes to SNpc aging. These data help understand the processes underlying SNpc aging and their potential contribution to age-related disorders like PD. © 2013 Gao et al.This work was funded by Spanish Ministry of Science and Education, Andalusian Government, and “Marcelino Botín” Foundation. “CIBERNED” (Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas) was funded by the Spanish “Carlos III” Institute of Health. LME was supported by the Spanish “Carlos III” Institute of Health. Support from the Spanish Ministry of Science and Education for MHF (“FPI” predoctoral fellowship) is also acknowledged.Peer Reviewe

Application of digital image correlation at the microscale in fiber-reinforced composites

Digital image correlation (DIC) is applied to analyzing the deformation mechanisms under transverse compression in a fiber-reinforced composite. To this end, compression tests in a direction perpendicular to the fibers were carried out inside a scanning electron microscope and secondary electron images obtained at different magnifications during the test. Optimum DIC parameters to resolve the displacement and strain field were computed from numerical simulations of a model composite and they were applied to micrographs obtained at different magnifications (250_, 2000_, and 6000_). It is shown that DIC of low-magnification micrographs was able to capture the long range fluctuations in strain due to the presence of matrix-rich and fiber-rich zones, responsible for the onset of damage. At higher magnification, the strain fields obtained with DIC qualitatively reproduce the non-homogeneous deformation pattern due to the presence of stiff fibers dispersed in a compliant matrix and provide accurate results of the average composite strain. However, comparison with finite element simulations revealed that DIC was not able to accurately capture the average strain in each phase

Mecanismos de Deformación en laminados de matriz polimérica correlación digital de imágenes y micromecánica computacional

Se ha realizado un estudio micromecánico experimental del comportamiento de laminados unidireccionales sometidos a compresión en la dirección perpendicular a las fibras. Se ha empleado la técnica de correlación digital de imágenes para observar la evolución de los campos de desplazamientos y deformaciones en la microestructura del material compuesto. En los contornos de deformación obtenidos experimentalmente se ha comprobado como las fibras tienen una deformación muy pequeña, mientras que las mayores deformaciones se concentran en las zonas de matriz de menor fracción volumétrica de fibras. Simulando por elementos finitos la microestructura estudiada se han reproducido los resultados experimentales, obteniendo distribuciones de campos de desplazamientos y deformaciones muy similares a las observadas experimentalmente

Colposcopy in the Primary Health Care: A Scoping Review

Aim: Low- and middle-income countries represent nearly 85% of all cervical cancer cases worldwide; thereby, it is extremely important to identify methods to improve the screening process. Therefore, this study aimed to summarize the primary characteristics of studies on accessibility, coverage, patient preferences, and factors associated with patient satisfaction or acceptance of colposcopy in primary healthcare. Methods: A search strategy, based on MeSH, Emtree, and free terms, was run through 5 databases (PubMed, Scopus, Embase, Ovid/Medline, and Web of Science). EndNote 20.1 © and Rayyan QCRI © were used for screening. A preset datasheet was used for data extraction. Results: The systematic search retrieved 1127 references, and after removing duplicates, screening the titles and abstracts, and reviewing the full text, 7 studies were included. The interrater reliability was 77.73% (kappa statistic = 0.1842). Most studies estimated the proportion of women that sought for colposcopy after a previous screening test for human papilloma virus. One study identifies barriers to colposcopy examination in women at risk of developing cervical cancer. Three studies assessed the decentralization of colposcopy from a tertiary healthcare center to a primary care center. Pap smear was the most common first-line screening test, followed by liquid-based cytology sample and visual inspection with acetic acid. Conclusion: Only a few countries have investigated the use of colposcopy in primary care. Thus, barriers and the care structure for this implementation to be successful in reducing cervical cancer incidence and mortality should be identified.Revisión por pare

Application of texture analysis to muscle MRI: 1-What kind of information should be expected from texture analysis?

Several previous clinical or preclinical studies using computerized texture analysis of MR Images have demonstrated much more clinical discrimination than visual image analysis by the radiologist. In muscular dystrophy, a discriminating power has been already demonstrated with various methods of texture analysis of magnetic resonance images (MRI-TA). Unfortunately, a scale gap exists between the spatial resolutions of histological and MR images making a direct correlation impossible. Furthermore, the effect of the various histological modifications on the gray level of each pixel is complex and cannot be easily analyzed. Consequently, clinicians will not accept the use of MRI-TA in routine practice if TA remains a “black box” without clinical correspondence at a tissue level. A goal therefore of the multicenter European COST action MYO-MRI is to optimize MRI-TA methods in muscular dystrophy and to elucidate the histological meaning of MRI textures.info:eu-repo/semantics/publishedVersio