What explains the invading success of the aquatic mud snail Potamopyrgus antipodarum (Hydrobiidae, Mollusca)?

The spread of non-native species is one of the most harmful and least reversible disturbances in ecosystems. Species have to overcome several filters to become a pest (transport, establishment, spread and impact). Few studies have checked the traits that confer ability to overcome these steps in the same species. The aim of the present study is to review the available information on the life-history and ecological traits of the mud snail, Potamopyrgus antipodarum Gray (Hydrobiidae, Mollusca), native from New Zealand, in order to explain its invasive success at different aquatic ecosystems around the world. A wide tolerance range to physico-chemical factors has been found to be a key trait for successful transport. A high competitive ability at early stages of succession can explains its establishment success in human-altered ecosystems. A high reproduction rate, high capacity for active and passive dispersal, and the escape from native predators and parasites explains its spread success. The high reproduction and the ability to monopolize invertebrate secondary production explain its high impact in the invaded ecosystems. However, further research is needed to understand how other factors, such as population density or the degree of human perturbation can modify the invasive success of this aquatic snai

Causes and consequences of chromosome segregation errors in the mouse preimplantation embryo

La division cellulaire est un processus biologique universel nécessaire à la reproduction, au développement, à la survie cellulaire ainsi qu’à la réparation des tissus. Une ségrégation chromosomique exacte pendant la mitose est essentielle pour une répartition égale des chromosomes répliqués entre les cellules filles. Des erreurs dans la ségrégation des chromosomes mènent à une condition appelée aneuploïdie, définie par un nombre inadéquat de chromosomes dans une cellule. L’aneuploïdie est associée à une altération de la santé cellulaire, la tumorigénèse, des malformations congénitales et l'infertilité. Contre toute attente, les embryons préimplantatoires de mammifères, dont les humains, consistent souvent en un mélange de cellules euploïdes et de cellules aneuploïdes. Ce mosaïcisme est inexorablement causé par des erreurs dans la ségrégation des chromosomes au cours des divisions mitotiques suivant la fécondation et est associé à un potentiel de développement réduit lors des traitements de fertilité. Malgré sa découverte il y a 25 ans, les mécanismes qui sous-tendent l’apparition de l'aneuploïdie mosaïque dans les embryons préimplantatoires sont toujours méconnus. Pour explorer les causes et les conséquences des erreurs de ségrégation chromosomique, des approches d'imagerie de fine pointe ont été utilisées sur des embryons préimplantatoires murins. L'analyse de la dynamique de la ségrégation des chromosomes via l’imagerie de cellules vivantes a permis d’identifier les chromosomes retardataires, lors de l’anaphase, comme la forme la plus répandue des erreurs de ségrégation. Ces chromosomes retardataires entraînent fréquemment une encapsulation de chromosome unique dans une structure appelée micronoyau. D'autres expériences d'imagerie par immunofluorescence sur des cellules vivantes ou fixées ont révélé que les chromosomes des micronoyaux subissent des dommages importants à l'ADN et sont mal répartis de manière récurrente lors des divisions cellulaires subséquentes dans la phase préimplantatoire. D’autres approches ont aussi permis d’examiner l'efficacité du mécanisme de contrôle de l’assemblage du fuseau mitotique, (SAC pour Spindle Assembly Checkpoint). Les résultats obtenus attestent que le SAC fonctionne, cependant la signalisation liée au SAC n’est pas efficace et ne permet pas de différer l'anaphase, malgré la présence de chromosomes retardataires et ce indépendamment de la taille des cellules. Les résultats présentés révèlent aussi qu’une inhibition partielle d’une cible du SAC, le complexe de promotion de l'anaphase (APC/C), cause une mitose prolongée et une réduction des erreurs de ségrégation. En outre, les études présentées démontrent que la fonction déficiente du SAC pendant le développement préimplantatoire est la cause principale d’une forte incidence de chromosomes retardataires qui entraînent une mauvaise ségrégation chromosomique répétée et qui causent une aneuploïdie mosaïque dans l’embryon. De plus, ce travail fournit la preuve que la modulation pharmacologique de la signalisation SAC-APC/C permet d’éviter les erreurs de ségrégation des chromosomes dans les embryons précoces. En conclusion, ces résultats apportent de nouvelles perspectives sur les causes et la nature des erreurs de ségrégation chromosomique dans les embryons. De plus, ce travail apporte de nouvelles explications mécanistiques sur l'apparition du mosaïcisme dans les embryons ce qui aura des implications importantes dans la détection et la prévention thérapeutique potentielle de l'aneuploïdie mosaïque dans les embryons préimplantatoires.Cell division is a universal biological process necessary for reproduction, development, cell survival and the maintenance and repair of tissues. Accurate chromosome segregation during mitosis is essential to ensure replicated chromosomes are partitioned equally into daughter cells. Errors in chromosome segregation often result in cells with abnormal numbers of chromosomes, a condition termed aneuploidy, which is associated with impaired cellular health, tumorigenesis, congenital defects and infertility. Counterintuitively, preimplantation embryos from many mammalian species, including humans, often consist of a mixture euploid and aneuploid cells. Such mosaic aneuploidy in embryos is inexorably caused by errors in chromosome segregation during mitotic divisions following fertilization and has been associated with reduced developmental potential in fertility treatments. However, ever since its discovery 25 years ago, how and why mosaic aneuploidy arises in the preimplantation embryo has remained elusive. To explore the causes and consequences of embryonic chromosome segregation errors, advanced imaging approaches were employed in the mouse preimplantation embryo. Live cell imaging analysis of chromosome segregation dynamics identified lagging anaphase chromosomes as the most prevalent form of chromosome mis-segregation in embryos. Lagging chromosomes frequently result in the encapsulation of single chromosomes into micronuclei, which occur in embryos in vitro and in vivo. Further live imaging and immunofluorescence experiments revealed chromosomes within micronuclei are subject to extensive DNA damage and centromeric identity loss, failing to assemble functional kinetochores and being recurrently mis-segregated during ensuing cell divisions in preimplantation development. To uncover the underlying causes for the increased propensity for chromosome mis-segregation in embryos, live imaging and loss-of-function approaches were used to examine the effectiveness of the mitotic safeguard mechanism, the Spindle Assembly Checkpoint (SAC). These studies demonstrated that the SAC normally functions to prevent segregation errors during preimplantation development but SAC signaling at misaligned chromosomes fails to delay anaphase. Moreover, SAC failure in embryos is most evident during mid-preimplantation development, independent of cell size. Partial inhibition of SAC target, the Anaphase Promoting Complex (APC/C), extended mitosis and reduced chromosome segregation errors in embryos. These studies have uncovered deficient SAC function during preimplantation development as a major cause for the high incidence of lagging chromosomes in embryos, which result in repeated mis-segregation of single chromosomes in a manner that necessarily causes mosaic aneuploidy. Additionally, this work provides proof-of-principle demonstration that pharmacological modulation of SAC-APC/C signalling can avert chromosome segregation errors in the early embryo. Altogether, these findings present new insights into the causes and nature of chromosome mis-segregation in embryos, providing novel mechanistic explanations for the occurrence of mosaicism that will have substantial implications for the detection and potential therapeutic prevention of aneuploidy in preimplantation embryos

El Trabajo Social y su acción profesional

Fombuena, J. (2020). El Trabajo Social y su acción profesional. Nau Llibres.Fombuena, J. (2020). El Trabajo Social y su acción profesional. Nau Llibres

Energy spectrum and Landau levels in bilayer graphene with spin-orbit interaction

We present a theoretical study of the bandstructure and Landau levels in bilayer graphene at low energies in the presence of a transverse magnetic field and Rashba spin-orbit interaction in the regime of negligible trigonal distortion. Within an effective low energy approach (L\"owdin partitioning theory) we derive an effective Hamiltonian for bilayer graphene that incorporates the influence of the Zeeman effect, the Rashba spin-orbit interaction, and inclusively, the role of the intrinsic spin-orbit interaction on the same footing. Particular attention is spent to the energy spectrum and Landau levels. Our modeling unveil the strong influence of the Rashba coupling $\lambda_R$ in the spin-splitting of the electron and hole bands. Graphene bilayers with weak Rashba spin-orbit interaction show a spin-splitting linear in momentum and proportional to $\lambda_R$, but scales inversely proportional to the interlayer hopping energy $\gamma_1$. However, at robust spin-orbit coupling $\lambda_R$ the energy spectrum shows a strong warping behavior near the Dirac points. We find the bias-induced gap in bilayer graphene to be decreasing with increasing Rashba coupling, a behavior resembling a topological insulator transition. We further predict an unexpected assymetric spin-splitting and crossings of the Landau levels due to the interplay between the Rashba interaction and the external bias voltage. Our results are of relevance for interpreting magnetotransport and infrared cyclotron resonance measurements, including also situations of comparatively weak spin-orbit coupling.Comment: 25 pages, 5 figure

Analysis of the Real Energy Consumption of Energy Saving Lamps

[Abstract] Light emitting diode (LED) and compact fluorescent light (CFL) lamps are widely used because they are associated with low energy consumption and a reduced environmental impact. In the present paper, a study of the real consumption of these devices has been carried out. To do this, the active, reactive, distortion and apparent power and electrical efficiency for various lamps have been measured and calculated. The distortions produced in the network provoke the consumed energy to be in the order of 50–75% higher than that which appears in the commercial characteristics. This situation means that for its operation, it is necessary to generate and distribute an amount of energy much higher than that which is declared as the consumption of these lamps, and so far, this amount of energy is neither quantified nor invoiced. Additionally, groups of lamps have also been studied to check whether, when working together on the same network, there is a compensation phenomenon that reduces the negative effects of individual lamps. We have found that this compensation effect does not occur for the type of devices evaluated

Una comunidad de aprendizaje virtual y colaborativa para egresados de diseño industrial de una universidad privada de Lima

Este proyecto de innovación se presenta como respuesta al problema de la amplia dispersión de información en las áreas técnica y práctica con que cuenta el egresado de Diseño Industrial de una universidad privada de Lima, repercutiendo en su desempeño profesional. Se pretende establecer la manera de tomar con los egresados de esa casa de estudios, un compromiso a través de actitudes y propuestas innovadoras que no son más que el seguimiento de su formación profesional en la vida diaria. El crecimiento de la tecnología ha traído consigo aportes de considerable magnitud para los medios de comunicación, y con ello grandes cambios en nosotros, como personas, comunidad, y mundo. Aprender colaborando, intercambiando opiniones es una manera de contribuir al enriquecimiento del saber. Se establecen objetivos claros para fomentar el trabajo y aprendizaje colaborativo en red entre egresados y docentes de la Especialidad de Diseño Industrial, generar entornos de trabajo sistemático para la reflexión del diseño, propiciar un espacio de la comunicación y seguimiento de la trayectoria profesional de los egresados de la carrera de Diseño Industrial. Estos objetivos se desarrollan mediante una planificación a detalle de cada una de las fases que componen el desarrollo de la propuesta en cada fase se identifica una estrategia la cual conlleva a una acción para luego terminar en una prueba piloto que estará en interacción con los usuarios finales. Toda esta experiencia va a dejarnos una retroalimentación, necesaria para los cambios que ameriten el reordenamiento de la propuesta y ponerla en marcha de manera definitiva.Tesi

No. 07: The Urban Food System of Mexico City, Mexico

This report provides an overview of Greater Mexico City and its food system. The city’s history, demographic characteristics, geography and economy are first discussed. The city’s urban food system and urban food security are then examined with a particular focus on formal and informal food retail, food expenditure patterns, and policies to combat hunger and food insecurity. Meeting the daily food demands of Mexico City’s over 20 million inhabitants requires the agricultural production of Mexico’s rural areas, its fishing industry and food imports. Food products arrive in the city from around the country in a combination of traditional and highly sophisticated modern systems of food supply and distribution. Structural changes in recent decades have led to modifications in the systems of supply, distribution and food consumption with vertically integrated companies now controlling aspects of the food chain. The system of supply and marketing of food products is also characterized by competition between public markets, large wholesale and retail companies, and neighbourhood convenience stores. While levels of household food insecurity (undernutrition) are lower than in other global cities of the South, Mexico City faces an epidemic of overnutrition, obesity and non-communicable diseases

Detection and automatic identification of car plates

This work is a pattern recognition application using digital images processing and neural networks, applied to the automatic recognition of car plates. There is a wide range of problems to be solved, which go from the segmentation of the useful section of the image, to the use of neural networks to carry out a correct identification. The purpose of this work is not only to achieve the implementation of a specific tool to classify car plates, but also to compare the solutions provided by applying digital images processing and neural networks.Computación Gráfica y VisualizaciónRed de Universidades con Carreras en Informática (RedUNCI

Detection of saffron adulteration with gardenia extracts through the determination of geniposide by liquid chromatography-mass spectrometry

A new and sophisticated saffron adulteration method with gardenia was recently discovered in the European saffron market. In this work, an analytical methodology using liquid chromatography (quadrupole-time of flight)-mass spectrometry has been developed for the detection of the adulteration of saffron samples with gardenia through the determination of geniposide as an adulteration marker. A fused-core C18 column was employed using an isocratic elution with water:acetonitrile (85:15 v/v) containing 0.1% formic acid. After optimization of the mass spectrometry conditions, the analytical characteristics related to the determination of geniposide in negative electrospray ionization mode were evaluated. Then, it was possible to detect up to 10 ng/mL geniposide after a dilution step of 50-fold of the saffron extract (LOD of 41.7 mu g of geniposide per gram of sample analysed (i.e up to 0.004%)). The developed LC-MS methodology was applied to the analysis of different authentic and suspicious saffron samples. (C) 2016 Elsevier Inc. All rights reserved