Mean curvature and compactification of surfaces in a negatively curved Cartan-Hadamard manifold

We state and prove a Chern-Osserman-type inequality in terms of the volume growth for complete surfaces with controlled mean curvature properly immersed in a Cartan-Hadamard manifold $N$ with sectional curvatures bounded from above by a negative quantity $K_{N}\leq b<0$Comment: 24 page

RRAM variability and its mitigation schemes

Emerging technologies such as RRAMs are attracting significant attention due to their tempting characteristics such as high scalability, CMOS compatibility and non-volatility to replace the current conventional memories. However, critical causes of hardware reliability failures, such as process variation due to their nano-scale structure have gained considerable importance for acceptable memory yields. Such vulnerabilities make it essential to investigate new robust design strategies at the circuit system level. In this paper we have analyzed the RRAM variability phenomenon, its impact and variation tolerant techniques at the circuit level. Finally a variation-monitoring circuit is presented that discerns the reliable memory cells affected by process variability.Peer ReviewedPostprint (author's final draft

Kinetic Model for Micro Algae Cell Concentration and Size Distribution: Application to Nannochloropsis gaditana

The cell concentration and size distribution of the microalgae Nannochloropsis gaditana were studied over the whole growth process. Various samples were taken during the light and dark periods the algae were exposed to. The distributions obtained exhibited positive skew, and no change in the type of distribution was observed during the growth process. The size distribution shifted to lower diameters in dark periods while in light periods the opposite occurred. The overall trend during the growth process was one where the size distribution shifted to larger cell diameters, with differences between initial and final distributions of individual cycles becoming smaller. A model based on the Logistic model for cell concentration as a function of time in the dark period that also takes into account cell respiration and growth processes during dark and light periods, respectively, was proposed and successfully applied. This model provides a picture that is closer to the real growth and evolution of cultures, and reveals a clear effect of light and dark periods on the different ways in which cell concentration and diameter evolve with time.The Authors wish to thank Repsol YPF for the financial support that provided (Project reference: Ingenio 2010-CDTI-Sost CO2-CEN-2008-1027) and the Generalitat Valenciana by the fellowship of one of the authors (Program VALI + D)

Statistical analysis and comparison of 2T and 3T1D e-DRAM minimum energy operation

Bio-medical wearable devices restricted to their small-capacity embedded-battery require energy-efficiency of the highest order. However, minimum-energy point (MEP) at sub-threshold voltages is unattainable with SRAM memory, which fails to hold below 0.3V because of its vanishing noise margins. This paper examines the minimum-energy operation point of 2T and 3T1D e-DRAM gain cells at the 32-nm technology node with different design points: up-sizing transistors, using high- V th transistors, read/write wordline assists; as well as operating conditions (i.e., temperature). First, the e-DRAM cells are evaluated without considering any process variations. Then, a full-factorial statistical analysis of e-DRAM cells is performed in the presence of threshold voltage variations and the effect of upsizing on mean MEP is reported. Finally, it is shown that the product of the read and write lengths provides a knob to tradeoff energy-efficiency for reliable MEP energy operation.Peer ReviewedPostprint (author's final draft

Mean curvature and compactification of surfaces in a negatively curved Cartan–Hadamard manifold

We state and prove a Chern–Osserman-type inequality in terms of the volume growth for complete surfaces with controlled mean curvature properly immersed in a Cartan–Hadamard manifold N with sectional curvatures bounded from above by a negative quantity KN ≤ b < 0

Strategies to enhance the 3T1D-DRAM cell variability robustness beyond 22 nm

3T1D cell has been stated as a valid alternative to be implemented on L1 memory cache to substitute 6T, highly affected by device variability as technology dimensions are reduced. In this work, we have shown that 22 nm 3T1D memory cells present significant tolerance to high levels of device parameter fluctuation. Moreover, we have observed that when variability is considered the write access transistor becomes a significant detrimental element on the 3T1D cell performance. Furthermore, resizing and temperature control have been presented as some valid strategies in order to mitigate the 3T1D cell variability.Peer ReviewedPostprint (author's final draft

Datos de alimentación de ofidios en el levante sur ibérico

De las ocho especies de ofidios presentes en el levante sur ibérico se estudia en este trabajo el espectro trófico de cinco de ellos (C. hippocrepis, C. girondica, E, scalaris, M. monspessulanus y N. maura). Las tres especies no tratadas aquí más que marginalmente son M. cucullatus, N. natrix y V. latasti. C. hippocrepis y E. scalaris son especies básicamente homeotermófagas, C. girondica es casi exclusivamente sauriófaga, N. maura muestra una dieta en la que predominan los anfibios, pero formada también por peces, artrópodos y otros invertebrados, y M. monspessulanus preda sobre homeo y poiquilotermos de forma bastante equilibrada. El valor de la diversidad trófica por presa oscila entre 2.2 y 2.5 en C. hippocrepis, C. girondica, E. scalaris y N. maura, y vale 3.1 en M. monspessulanus, la especie más eurífaga. Se comparan los resultados obtenidos con los que proporciona Valverde (1967) para Andalucía y se discute la supuesta independencia de las distintas microcomunidades que preconiza el mencionado autor. Con los datos de peso seco no parece aplicable tal hipótesis a la herpetocenosis ya que los ofidios predan más de un setenta por ciento de la biomasa en el conjunto de las taxocenosis anfibia, ornítica y mamífera. Se sugiere que la independencia de cada microcomunidad de vertebrados terrestres es función inversa de la antigüedad del grupo.The trophic spectrum of five of the eight species of snakes occurring in the south east of Spain are studied here (C. hippocrepis, C. girondica, E. scalaris, M. monspessulanus and N. maura). The other three species studied slightly are, N. natrix, M. cucullatus and V. latasti. C. hippocrepis and E. scalaris are species basically homeotermophagous, C. girondica is near exclusively sauriophagous, N. maura shows a diet based mainly on amphibious but including as well fishes, arthropods and other invertebrates, and M. monspessulanus feeds itself with homeo and poiquilotermous in equal terms. The value of the trophic diversity per specie varies between 2.2 and 2.5 in C. hippocrepis, C. girondica, E. scalaris and N. maura and its value is 3.5 in M. monspessulanus the most euriphagous of the species. We compare our results with those obtained by Valverde (1967) and his hypothesis about the independence among the different microcommunities is discussed as well; With the data of dry weight it doesn't seem applicable such hypothesis towards herpetocenosis because snakes eat more than a 70 % of the biomass in the whole amphibious, ornitic and mammal taxocenosis. We suggest that the independence of each microcommunity of terrestrial vertebrates is an inverse function of group's antiquity

La resolución numérica de ecuaciones de Viète y su difusión en el curso matemático de Hérigone

Postprint (published version

Estacionalidad del tráfico de cruceros en las Islas Canarias y la complementariedad entre rutas de crucero

[ESP] España es una potencia europea receptora de tráfico de cruceros, con actividad crucerista en los puertos de sus tres zonas litorales. El presente trabajo determina el patrón de estacionalidad, y su evolución, del tráfico de cruceros en los puertos de las Islas Canarias con objeto de determinar si existe complementariedad estacional entre zonas de crucero españolas. Como método para analizar la evolución de la estacionalidad se aplica el Coeficiente de Variación. En la determinación del patrón de estacionalidad y su evolución, se emplea una serie temporal compuesta de 120 observaciones mensuales correspondientes al periodo de 2005 a 2014. [ENG] Spain is a European leader in cruise tourism, with cruising activity in its three coastal areas. This paper analyses cruise traffic seasonality pattern and its changes in the Canary Island ports in order to determine if there is seasonal complementarity between Spanish cruising regions. The analysis of the changes in seasonality is conducted using the coefficient of Variation. To determine the seasonality pattern and its changes is used a time series composed of 120 observations corresponding to monthly registers of the period 2005-2014.Centro Universitario de la Defensa. Escuela de Turismo de Cartagena. Escuela Técnica Superior de Ingeniería Industrial UPCT. Escuela Técnica Superior de Ingeniería de Telecomunicación (ETSIT). Escuela de Ingeniería de Caminos y Minas (EICM). Escuela de Arquitectura e Ingeniería de Edificación (ARQ&IDE). Parque Tecnológico de Fuente Álamo. Navantia. Campus Mare Nostrum. Estación Experimental Agroalimentaria Tomás Ferr