On Efficiency and Validity of Previous Homeplug MAC Performance Analysis

The Medium Access Control protocol of Power Line Communication networks (defined in Homeplug and IEEE 1901 standards) has received relatively modest attention from the research community. As a consequence, there is only one analytic model that complies with the standardised MAC procedures and considers unsaturated conditions. We identify two important limitations of the existing analytic model: high computational expense and predicted results just prior to the predicted saturation point do not correspond to long-term network performance. In this work, we present a simplification of the previously defined analytic model of Homeplug MAC able to substantially reduce its complexity and demonstrate that the previous performance results just before predicted saturation correspond to a transitory phase. We determine that the causes of previous misprediction are common analytical assumptions and the potential occurrence of a transitory phase, that we show to be of extremely long duration under certain circumstances. We also provide techniques, both analytical and experimental, to correctly predict long-term behaviour and analyse the effect of specific Homeplug/IEEE 1901 features on the magnitude of misprediction errors

Modeling, Analysis and Impact of a Long Transitory Phase in Random Access Protocols

In random access protocols, the service rate depends on the number of stations with a packet buffered for transmission. We demonstrate via numerical analysis that this state-dependent rate along with the consideration of Poisson traffic and infinite (or large enough to be considered infinite) buffer size may cause a high-throughput and extremely long (in the order of hours) transitory phase when traffic arrivals are right above the stability limit. We also perform an experimental evaluation to provide further insight into the characterisation of this transitory phase of the network by analysing statistical properties of its duration. The identification of the presence as well as the characterisation of this behaviour is crucial to avoid misprediction, which has a significant potential impact on network performance and optimisation. Furthermore, we discuss practical implications of this finding and propose a distributed and low-complexity mechanism to keep the network operating in the high-throughput phase.Comment: 13 pages, 10 figures, Submitted to IEEE/ACM Transactions on Networkin

A role for von Hippel-Lindau protein in pancreatic beta-cell function.

ObjectiveThe Vhlh gene codes for the von Hippel-Lindau protein (VHL), a tumor suppressor that is a key player in the cellular response to oxygen sensing. In humans, a germline mutation in the VHL gene leads to the von Hippel-Lindau disease, a familial syndrome characterized by benign and malignant tumors of the kidney, central nervous system, and pancreas.Research design and methodsWe use Cre-lox recombination to eliminate Vhlh in adult mouse pancreatic beta-cells. Morphology of mutant islets is assessed by immunofluorescence analysis. To determine the functional state of Vhlh(-/-) islets, insulin secretion is measured in vivo and in vitro, and quantitative PCR is used to identify changes in gene expression.ResultsLoss of VHL in beta-cells leads to a severe glucose-intolerant phenotype in adult animals. Although VHL is not required for beta-cell specification and development, it is critical for beta-cell function. Insulin production is normal in beta-cells lacking VHL; however, insulin secretion in the presence of high concentrations of glucose is impaired. Furthermore, the loss of VHL leads to dysregulation of glycolytic enzymes, pointing to a perturbation of the intracellular energy homeostasis.ConclusionsWe show that loss of VHL in beta-cells leads to defects in glucose homeostasis, indicating an important and previously unappreciated role for VHL in beta-cell function. We believe that the beta-cell-specific Vhlh-deficient mice might be a useful tool as a "genetic hypoxia" model, to unravel the possible link between hypoxia signaling and impairment of beta-cell function

Multi-domain ferroelectricity as a limiting factor for voltage amplification in ferroelectric field-effect transistors

We revise the possibility of having an amplified surface potential in ferroelectric field-effect transistors pointed out by [S. Salahuddin and S. Datta, Nano Lett. 8, 405 (2008)]. We show that the negative-capacitance regime that allows for such an amplification is actually bounded by the appearance of multi-domain ferroelectricity. This imposes a severe limit to the maximum step-up of the surface potential obtainable in the device. We indicate new device design rules taking into account this scenario.Comment: 4 pages, 3 figure

El coleccionismo de fotografía en España y la colección Castellano

La primera parte de este artículo repasa varias de las principales colecciones de fotografía en España de los siglos XIX y XX, centrándose en su proceso de institucionalización, mediante el cual el archivo personal de un fotógrafo se transforma en una colección. La segunda parte estudia una gran excepción dentro de este panorama, una colección privada de fotografía, la reunida por el pintor madrileño Manuel Castellano entre los años 1850 y 1875 aproximadamente. Un análisis de su contenido y de las anotaciones escritas sobre las fotografías sugiere algunos posibles criterios seguidos en la formación de la colección, en su presentación y sobre la forma en la que fue contemplada.The first part of this paper presents an overview of several of the principal photographic collections in Spain from the 19th and 20th centuries, focusing on their process of institutionalisation by which a photographer's personal archive is transformed into a collection. The second part studies a notable exception within this panorama: a private photographic collection assembled by the Madrid painter Manuel Castellano between 1850-1870, approximately. An analysis of its content and the written annotations about these photos suggests certain possible criteria followed in its presentation and regarding the way in which it was contemplated

Prevalencia de patógenos zoonósicos (virus de Influenza Aviar, flavivirus del Complejo Antigénico de la Encefalitis Japonesa y Salmonella spp.) y resultados preliminares de parasitofauna hemática en paloma doméstica (Columba livia doméstica) y animales de la colección del Parque zoológico Municipal de Córdoba

Premio extraordinario de Trabajo Fin de Máster curso 2013-2014. Medicina,Sanidad y Mejora Animal.Durante el periodo 2013-2014 se realizó un estudio transversal para determinar la prevalencia de patógenos zoonósicos y hemoparásitos en 154 palomas domésticas (Columba livia var. domestica) capturadas en el Parque Zoológico Municipal de Córdoba (PZMC) y en 93 muestras de animales de la colección del Parque. Las muestras de suero se analizaron para detectar anticuerpos frente a virus de la Influenza Aviar (VIA) y flavivirus del Complejo Antigénico de la Encefalitis Japonesa (CAEJ). Así mismo, se analizaron muestras de contenidos digestivos y heces para el aislamiento de Salmonella spp. Paralelamente, se determinó la frecuencia de infección de hemoparásitos en 60 palomas. No se detectaron anticuerpos frente a VIA en ninguna de las 148 (0,0%; IC95%:0,0- 1,9) palomas analizadas mediante bELISA, mientras que se confirmó seropositividad en 5 de 28 (18,5%; IC95%:6,0-31,0) aves de la colección. Once de 142 (8,5%; IC95%:4,0-12,9) sueros de palomas presentaron anticuerpos frente a flavivirus del CAEJ mediante bELISA. Además, 4 de los 49 (8,2%; IC95%:1,9-14,5) ejemplares de la colección analizados resultaron seropositivos frente a flavivirus. El cultivo para el aislamiento de Salmonella spp. determinó ausencia de infección en las 152 muestras de contenido digestivo de paloma (0,0%; IC95%:0,0-1,9), mientras que 4 de 44 (9,1%; IC95%:1,0-17,2) muestras de heces de los animales de la colección resultaron positivas. Haemoproteus sub. Haemoproteus spp. fue detectado en 52 de las 60 (86,7%; IC95%:78,3-95,0) palomas analizadas. Los resultados obtenidos indican circulación de flavivirus del CAEJ en la población de palomas y animales del PZMC. Estas especies podrían ser usadas como centinelas para la monitorización de flavivirus en zonas urbanas. La ausencia de positividad frente a VIA y Salmonella spp., sugieren que las palomas no tienen un papel relevante en la epidemiología de estos patógenos. Los resultados determinan una elevada diseminación de Haemoproteus (H.) en las poblaciones de palomas del PZMC, lo cual podría tener implicación para la conservación de algunas especies de aves.A cross-sectional study was carried out to determine the prevalence of different pathogenic zoonotic agents and hemoparasites in 154 domestic pigeon (Columba livia var. domestica) and 93 samples of animals from the Córdoba Municipal Zoo Park (CMZP) between 2013 and 2014. Serum samples were tested to determine the presence of antibodies against Avian Influenza virus (AIV) and flaviviruses of the Japanese Encephalitis Antigenic Complex (JEAC). Moreover, samples of digestive content were analyzed for Salmonella spp. isolation. Seropositivity to AIV was not found in any of the 148 pigeons samples tested, while 5 out of 28 (18.5%; IC95%:6.0-31.0) zoo birds showed positive results using bELISA. A total of 11 out of 142 (8.5%; IC95%:4.0-12.9) pigeons analyzed presented antibodies to JEAC by bELISA. Thus, 4 out of 49 (8.2%; IC95%:1.9-14.5) zoo animals were seropositive against flaviviruses. Salmonella spp. was not isolated in any of the 152 intestine samples of pigeon (0.0%; IC95%:0.0-1.9), but 4 out of 44 samples (9.1%; IC95%:1.0-17.2) from zoo animals were positive. Finally, 52 out of 60 (86.7%; IC95%:78.3-95.0) were infected by Haemoproteus sub. Haemoproteus spp. The results obtained in the present study indicate circulation of flaviviruses of the JEAC in domestic pigeons and animals from the CMZP. The absence of seropositivity against AIV and the negative cultures to Salmonella spp. in the pigeons tested, suggest a limited role of this species in the epidemiology of both diseases. Parasitological results suggest a widespread of Haemoproteus (H.) in the pigeon population, which could has implications for the conservation of bird species

AIP and MEN1 mutations and AIP immunohistochemistry in pituitary adenomas in a tertiary referral center.

Background: Pituitary adenomas have a high disease burden due to tumor growth/ invasion and disordered hormonal secretion. Germline mutations in genes such as MEN1 and AIP are associated with early onset of aggressive pituitary adenomas that can be resistant to medical therapy. Aims: We performed a retrospective screening study using published risk criteria to assess the frequency of AIP and MEN1 mutations in pituitary adenoma patients in a tertiary referral center. Methods: Pituitary adenoma patients with pediatric/adolescent onset, macroadenomas occurring ≤30 years of age, familial isolated pituitary adenoma (FIPA) kindreds and acromegaly or prolactinoma cases that were uncontrolled by medical therapy were studied genetically. We also assessed whether immunohistochemical staining for AIP (AIP-IHC) in somatotropinomas was associated with somatostatin analogs (SSA) response. Results: Fifty-five patients met the study criteria and underwent genetic screening for AIP/MEN1 mutations. No mutations were identified and large deletions/duplications were ruled out using MLPA. In a cohort of sporadic somatotropinomas, low AIP-IHC tumors were significantly larger (P = 0.002) and were more frequently sparsely granulated (P = 0.046) than high AIP-IHC tumors. No significant relationship between AIP-IHC and SSA responses was seen. Conclusions: Germline mutations in AIP/MEN1 in pituitary adenoma patients are rare and the use of general risk criteria did not identify cases in a large tertiary-referral setting. In acromegaly, low AIP-IHC was related to larger tumor size and more frequent sparsely granulated subtype but no relationship with SSA responsiveness was seen. The genetics of pituitary adenomas remains largely unexplained and AIP screening criteria could be significantly refined to focus on large, aggressive tumors in young patients

On the use of logistic functions for coastal flood assessment

Coastal flooding results as the combination of wave conditions, mean water level and terrain characteristics. The associated damage can be expressed as a function of the flooding water column and it will rarely remain stationary in a sea level scenario. The objective of the study is to determine the importance of the dynamic (waves) and hydrostatic (sea level) component as a function of a damage level and to determine what combinations of hydrodynamic drivers may lead to unacceptable damage levels. The analysis has been performed through the use of logistic functions in the beach of Sant Pere Pescador (Girona province), covering an extension of 6,3 kilometres with an average width of 90m. The approach of the research consists of the creation of two multinomial regression models to be analyzed for 6 hydrodynamic scenarios derived from a coupled hydromorphodynamic model, one made in a node-by-node basis and the other one through polygons. The results show that a node-by-node model has nearly 10% of information loss due to the small variability and the small number of measurements. However, both models successfully predict similar expected prediction and probability to reach a flood categories for the proposed scenarios. Results from the multinomial regression clearly reveals sea level rise as the main contribution to flood increase, with the wave return period being less significant. The model also suggests that a drastic increase in the flooding water column, approximately between 0,6 and 1 m will occur for sea level rise bigger than 0,25m. According the IPCC predictions for the sea level rise in the Mediterranean Coast, this is expected to occur between a time range of 2040-2070 (for the RCP 8.5, the most dramatic climate scenario) or starting in 2045 (for RCP 2.6 and RCP 4.5, less severe scenarios). For what concerns the spatial extension of the flooding, the expected categories of flooding shows that the northern region of the Sant Pere Pescador beach is likely to suffer more severe flooding than the central and southern regions, both in intensity and spatial extent, reaching water depths larger than 0,6 - 1m for scenarios with sea level rise larger than 0,25m.Las inundaciones de costas son fenómenos causados por la combinación del oleaje, el nivel medio del mar y las características del terreno. El daño asociado puede ser expresado en función de la columna de agua de inundación, tomando diferentes valores para distintas situaciones de subida del nivel del mar. El objetivo del presente estudio es determinar la importancia de la componente dinámica (olas) e hidrostática (nivel del mar) como componentes de predicción del nivel de daño para poder determinar qué combinaciones de parámetros hidrodinámicos lleva a niveles de daño inaceptables. El análisis se ha llevado a cabo a través del uso de modelos logísticos en la zona de playa de Sant Pere Pescador (Provincia de Girona), cubriendo una extensión de 6,3 Km de largo con un ancho medio de 90m. Para su desarrollo, se han elaborados dos modelos multinomiales de regresión analizando 6 escenarios hidrodinámicos. Uno de los modelos se ha centrado en el estudio nodo a nodo y el otro mediante el análisis de polígonos. Los resultados muestran que, para el modelo nodo a nodo, hay una pérdida de cerca del 10% de la información inicial debido a la escasa variabilidad en la muestra y debido al reducido número de datos disponibles. No obstante, ambos modelos consiguen predecir de manera similar la probabilidad y la predicción de llegar a ciertas categorías de inundación para los distintos escenarios. Los resultados del modelo de regresión logística muestran la subida del nivel del mar como principal contribuyente al incremento de la cota de inundación, mientras que el período de retorno de la ola es menos significativo. El modelo también indica que para niveles de incremento del nivel del mar mayores que 0,25m, gran parte de la costa se va a ver seriamente afectada con inundaciones entre 0,6 y 1 metro de agua. Según las predicciones del IPCC, para incrementos del nivel del mar en la costa del Mediterráneo, se espera que una subida del nivel del mar alcance los 0,25m entre el 2040 y el 2070 (para el RCP 8.5, el escenario climático más severo) o 2045 (para escenarios climáticos menos graves como el RCP 2.6 y RCP 4.5). En cuanto a la extensión de la inundación, se prevé que en la zona norte de la Playa de Sant Pere Pescador se obtengan mayores categorías de inundación, en comparación con la zona centro y sur, debido a la elevación y la configuración de las dunas. Concretamente, se esperan valores de inundación entre 0,6m y 1m en la zona norte para escenarios de subida del nivel del mar mayor que 0,25m.Les inundacions de costes son fenòmens causats per la combinació de l’onatge, el nivell mig del mar i les característiques del terreny. Els danys associats poden ser expressats en funció de la columna d’aigua d’inundació, prenent valors variables en funció dels diferents escenaris d’augment del nivell. del mar. L’objectiu d’aquest treball és determinar la importància de la component dinàmica (onades) i hidrostàtica (nivell del mar) en la predicció del nivell de dany per tal de determinar quines combinacions dels paràmetres hidrodinàmics duen a nivells de dany inacceptables. L’anàlisi s’ha dut a terme a través de l’ús de models logístics en la zona de platja de Sant Pere Pescador (Província de Girona), cobrint una extensió de 6,3 Km de llarg i un ample mitjà de 90m. S’han analitzat 6 escenaris hidrodinàmics mitjançant l’elaboració de dos models multinomials, un centrat en l’estudi node a node i l’altre mitjançant polígons. Els resultats mostren que, per el model node a node, hi ha una pèrdua aproximada d’un 10% de la informació inicial, degut a l’escassa variabilitat en la mostra i al reduït nombre de dades mesurades. No obstant, ambdós models aconsegueixen predir de manera molt similar la probabilitat i les prediccions d’arribar a certes categories d’inundació per a diferents escenaris. Els resultats del model de regressió logístic mostra la pujada del nivell del mar com a principal contribuïdor a l’increment del nivell d’inundació, mentre que el període de retorn resulta menys significatiu. El model també indica que, per a nivells d’increment del mar majors de 0,25m, gran part de la costa es veurà greument afectada amb inundacions d’entre 0,6 i 1m d’aigua. Segons les prediccions del IPCC, s’espera que en la costa Mediterrània el nivell del mar pugi fins els 0,25m entre el 2040 i el 2070 (per el RCP 8.5, que és l’escenari climàtic més advers) o al 2045 (per a prediccions climàtiques menys greus, com el RCP 2.6 i 4.5) Pel que fa l’extensió de la inundació, es preveu que a la zona nord de la Platja de Sant Pere Pescador s’hi obtinguin majors cotes d’inundació que en les zones centre i sud, degut a l’elevació i la configuració de les dunes. Concretament, s’esperen valors d’inundació entre 0,6 i 1m per a escenaris on la pujada del nivell del mar sobrepassi els 0,25m