L'eficàcia del cribratge de càncer de mama mitjançant mamografia

Els resultats disponibles ens indiquen que el cribratge de càncer de mama mitjançant mamografia és eficaç per reduir la mortalitat per aquest càncer en les dones més grans de 50 anys i que per sota d'aquesta edat hi ha més incerteses. Per altra banda, comença a haver-hi estudis que ens suggereixen que, a més d'eficaç, pot ser efectiu quan s'aplica com a programa poblacional

Limitaciones hidráulicas al aporte de agua a las hojas y resistencia a la sequía

El estudio de las limitaciones hidráulicas en el xilema y, en particular, de la vulnerabilidad al embolismo, ha permitido entender mejor las respuestas de las plantas a la sequía. Sin embargo, quedan todavía muchas cuestiones sin resolver en aspectos tan fundamentales como el papel de las células vivas en el transporte xilemático, el mecanismo de recuperación de las embolias, o las interrelaciones entre los aspectos estructurales y funcionales del xilema. En este artículo se repasan algunas aportaciones recientes al debate sobre estas cuestiones. Igualmente, se discuten las posibles implicaciones de tener un xilema muy vulnerable al embolismo, como ocurre en especies como Quercus ilex o Pinus sylvestris, en el contexto de mayor aridez predicho por los modelos de cambio climático

Disseny d'un vehicle per a l'escaneig dels caps de les vies de tren

Actualment, el manteniment de les línies ferroviàries és de gran importància per a la prevenció de riscos i en aquest treball es presenta el disseny d’un vehicle autònom el qual pugui fer l'escaneig de l'estat intern de les vies, per al manteniment preventiu de les línies ferroviàries, concretament a línies Barcelona – Vallès i Llobregat – Anoia dels FGC. Existeixen diferents mètodes pel manteniment preventiu de les vies de tren que van des d'una lubricació manual de les vies, sistemes de mesura del desnivell entre vies per a trens d'alta velocitat fins a mesures per làser del desgast dels caps de les vies. Cap manteniment actual observa l'estat intern de les vies. Per això, arran d'un projecte en el qual participava la universitat de Birmingham, on utilitzaven un sistema de visualització de l'estat intern de vies de tren anomenat E.M.A.T. (Electro Magnetic Acoustic Transducer). S'ha dissenyat un vehicle automatitzat el qual detecta falles o fissures internes en les vies dels FGC i marca la seva posició per a un posterior manteniment correctiu de la secció afectada. Finalment, la proposta contempla el disseny del vehicle, estudi dels components comercials usats, costos, manual d'ús i manual de manteniment.Actualmente, el mantenimiento de las líneas ferroviarias es de gran importancia para la prevención de riesgos y en este trabajo se presenta el diseño de un vehículo autónomo que pueda escanear el estado interno de las vías, para hacer un mantenimiento preventivo de las líneas ferroviarias, concretamente a las líneas Barcelona – Vallès y Llobregat – Anoia de los FGC. Existen diferentes métodos por el mantenimiento preventivo de las vías de tren que van desde una lubricación manual de las vías, sistemas de medida del desnivel entre vías para trenes de alta velocidad hasta medidas por láser del desgaste de cabezas de las vías. Ningún mantenimiento actual observa el estado interno de las vías. Por eso, a raíz de un proyecto en el cual participaba la universidad de Birmingham, donde utilizaban un sistema de visualización del estado interno de vías de tren denominado E.M.A.T. (Electro Magnetic Acoustic Transducer). Se ha diseñado un vehículo automatizado el cual detecta fallas o fisuras internes en las vías de los FGC y marca su posición para un posterior mantenimiento correctivo de la sección afectada. Finalmente, la propuesta contempla el diseño del vehículo, estudio de los componentes comerciales usados, costes, manual de uso y manual de mantenimiento.Nowadays, the maintenance of railway lines is really important for risks preventions and in this project an autonomous vehicle is presented for the scanning of the internal state of the tracks, in order to carry out preventive maintenance of railway lines, specifically Barcelona – Vallès and Llobregat – Anoia FGC lines. There are many different methods for the preventive maintenance of railway tracks, from manual track lubrication, systems for measuring the difference in level between rails for high-speed trains, to laser measurements of rail head wear. No current maintenance system monitors the internal condition of the rails. Therefore, starting from a project in which the University of Birmingham was involved, where using a system for visualising the internal condition of railway tracks called E.M.A.T. (Electro Magnetic Acoustic Transducer). An automated vehicle has been designed which detects internal faults or fissures in FGC tracks and marks their position for subsequent corrective maintenance of the affected section. Finally, this proposal includes the design of the vehicle, study of the commercial components used, costs, user manual and maintenance manual

Distinct macroinvertebrate soil food webs at one-meter scale in a Mediterranean agroecosystem

Altres ajuts: Acord transformatiu CRUE-CSICSoil macroinvertebrates play a central role in ecosystem processes such as decomposition and nutrient cycling, but the extent to which macroinvertebrate food web structure varies within ecosystems is basically unknown. Here, we examined changes in plant and macroinvertebrate community composition at increasing distances from trees within a citrus grove, following a gradient in organic matter and water availability created by the localized fertilization and irrigation of citrus trees. In addition, we analysed stable isotope signatures (δC and δN) of soil, plants, and macroinvertebrates to investigate changes in trophic structure within the grove. The macroinvertebrate community near the tree trunks had a higher number of detritivores and predators than the community located farther away. After correcting the isotope values of macroinvertebrates by their isotopic baseline, a spatial shift in trophic structure emerged: macroinvertebrates near the trunks had lower δC-values than those located farther away (i.e., they apparently relied more on plant- based resources). This pattern is attributable to species only found near the trunks. In contrast, species distributed across the studied area showed no differences in their isotopic signatures across space, suggesting that they are connecting otherwise two compartmentalized food webs. A reduction in organic matter and water availability at increasing distances from trees is the most parsimonious explanation of the observed isotopic gradient in soil and plants, and this may, in turn, be responsible for the observed changes in food web composition and structure. This study shows that spatial variability in macroinvertebrate soil food webs can be present at scales as small as one meter if spatial variability in environmental factors is high enough

Drastic reduction of false positive species in samples of insects by intersecting the default output of two popular metagenomic classifiers

The use of high-throughput sequencing to recover short DNA reads of many species has been widely applied on biodiversity studies, either as amplicon metabarcoding or shotgun metagenomics. These reads are assigned to taxa using classifiers. However, for different reasons, the results often contain many false positives. Here we focus on the reduction of false positive species attributable to the classifiers. We benchmarked two popular classifiers, BLASTn followed by MEGAN6 (BM) and Kraken2 (K2), to analyse shotgun sequenced artificial single-species samples of insects. To reduce the number of misclassified reads, we combined the output of the two classifiers in two different ways: (1) by keeping only the reads that were attributed to the same species by both classifiers (intersection approach); and (2) by keeping the reads assigned to some species by any classifier (union approach). In addition, we applied an analytical detection limit to further reduce the number of false positives species. As expected, both metagenomic classifiers used with default parameters generated an unacceptably high number of misidentified species (tens with BM, hundreds with K2). The false positive species were not necessarily phylogenetically close, as some of them belonged to different orders of insects. The union approach failed to reduce the number of false positives, but the intersection approach got rid of most of them. The addition of an analytic detection limit of 0.001 further reduced the number to ca. 0.5 false positive species per sample. The misidentification of species by most classifiers hampers the confidence of the DNA-based methods for assessing the biodiversity of biological samples. Our approach to alleviate the problem is straightforward and significantly reduced the number of reported false positive species