Crosstalk between nanotube devices: contact and channel effects

At reduced dimensionality, Coulomb interactions play a crucial role in determining device properties. While such interactions within the same carbon nanotube have been shown to have unexpected properties, device integration and multi-nanotube devices require the consideration of inter-nanotube interactions. We present calculations of the characteristics of planar carbon nanotube transistors including interactions between semiconducting nanotubes and between semiconducting and metallic nanotubes. The results indicate that inter-tube interactions affect both the channel behavior and the contacts. For long channel devices, a separation of the order of the gate oxide thickness is necessary to eliminate inter-nanotube effects. Because of an exponential dependence of this length scale on dielectric constant, very high device densities are possible by using high-k dielectrics and embedded contacts

Experimental techniques for ductile damage characterisation

Ductile damage in metallic materials is caused by the nucleation, growth and coalesce of voids and micro-cracks in the metal matrix when it is subjected to plastic strain. A considerable number of models have been proposed to represent ductile failure focusing on the ultimate failure conditions; however, only some of them study in detail the whole damage accumulation process. The aim of this work is to review experimental techniques developed by various authors to measure the accumulation of ductile damage under tensile loads. The measurement methods reviewed include: stiffness degradation, indentation, microstructure analysis, ultrasonic waves propagation, X-ray tomography and electrical potential drop. Stiffness degradation and indentation techniques have been tested on stainless steel 304L hourglass-shaped samples. A special interest is placed in the Continuum Damage Mechanics approach (CDM) as its equations incorporate macroscopic parameters that can represent directly the damage accumulation measured in the experiments. The other main objective lies in identifying the strengths and weaknesses of each technique for the assessment of materials subjected to different strain-rate and temperature conditions

Retroceso de escarpes en ambientes semiáridos a partir de facetas triangulares de ladera (depresión del Ebro)

[Resumen] La evolución de las laderas en las regiones áridas puede dar lugar a la generaciónde facetas triangulares de ladera situadas al pie de relieves estructurales. Al Surde Zaragoza (Depresión del Ebro) existe un buen ejemplo de secuencias de facetas triangulares donde se pueden identificar cinco estadios de evolución de laderas (Sl a Ss' de la más reciente a la más antigua). Los depósitos de estas laderas contienen fragmentos de cerámicas, carbón vegetal y cenizas que permiten obtener dataciones relativas y absolutas. El contenido en cerámicas de las acumulaciones indica una edad final de generación posterior al siglo XIX para Sl y posterior al Bronce Medio-Final (3.500-3.100 BP) para S2. Las dataciones por Carbono-14 obtenidas son 2.529±52 BP y 2.930±60 BP para S2' 27.862±444 BP para S3 y 35.570±490 BP' para S4. La acumulación más antigua no ha podido ser datada. La extrapolación de las ecuaciones logarítmicas ajustadas a los perfiles de las facetas permite calcular los retrocesos del escarpe. Los datos obtenidos indican velocidades de retroceso del escarpe de 0.9-1 m/l.000 años para los últimos 35.000 años.[Abstract] Slope evolution in arid regions may result in the development of talus flatiron sequences at the foot of structural reliefs. A good example exists to the South of Zaragoza (Ebro Basin), where five stages of slope evolution have been identified in the talus flatiron sequences (Sl to Ss' youngest to oldest). The deposits of these slopes contain pottery remains, charcoal and ashes which permit to carry out relative and absolute datings of the slope accumulations. Based on the pottery content, the most recent accumulation stage (Sl) is post-19th century. The pottery remains of the previous one (S2) indicate an age post-Middle-Late Bronze (3.5003.100 BP) and 14C datings obtained for this accumulation are 2.529±52 BP and 2.930±60 BP. The talus flatirons S3 have provided an age of 27.862±444 BP by 14C and for S4 the age is 35.570±490 BP. The oldest accumulation has not been dated. The extrapolation of the logaritmic equation fit from the talus flatiron profiles allows to calculate the scarp retreats. The data supplied indicate rates of scarp retreat of 0.9-1 m/1.000 years over the past 35.000 years

Phase Separation Driven by External Fluctuations

The influence of external fluctuations in phase separation processes is analysed. These fluctuations arise from random variations of an external control parameter. A linear stability analysis of the homogeneous state shows that phase separation dynamics can be induced by external noise. The spatial structure of the noise is found to have a relevant role in this phenomenon. Numerical simulations confirm these results. A comparison with order-disorder noise induced phase transitions is also made.Comment: 4 pages, 4 Postscript figures included in text. LaTeX (with Revtex macros

Quantum kernels to learn the phases of quantum matter

Classical machine learning has succeeded in the prediction of both classical and quantum phases of matter. Notably, kernel methods stand out for their ability to provide interpretable results, relating the learning process with the physical order parameter explicitly. Here we exploit quantum kernels instead. They are naturally related to the fidelity, and thus it is possible to interpret the learning process with the help of quantum information tools. In particular, we use a support vector machine (with a quantum kernel) to predict and characterize second-order quantum phase transitions. We explain and understand the process of learning when the fidelity per site (rather than the fidelity) is used. The general theory is tested in the Ising chain in transverse field. We show that for small-sized systems, the algorithm gives accurate results, even when trained away from criticality. Besides, for larger sizes we confirm the success of the technique by extracting the correct critical exponent ¿. Finally, we present two algorithms, one based on fidelity and one based on the fidelity per site, to classify the phases of matter in a quantum processor

Zymological indicators: a new concept applied to the detection of potential spoilage yeast species associated with fruit pulps and concentrates

DOI:10.1006/fmic.2000.0360; available online at http://www.idealibrary.comIn a survey of the microbial quality of raw materials used in fruit juice processing, yeast counts in fruit concentrates and pulps were found to range from51to 2?96103 cfu g71. Ascomycetous yeasts were representedby 76%of the isolateswhile 24%were basidiomycetes.The identi¢cation of strains isolated by the simpli¢ed identi¢cation system(SIM) revealed19 yeast species representing12 genera.Themost frequently isolated yeasts belonged to the genera Saccharomyces, Pichia, Cryptococcus, Kluyvero- myces and Candida. Fatty acid yeast composition allowed the separation of contaminating yeasts into one of threemajor groups. Group I included yeasts without linoleic (C 18:2) and linolenic (C 18:3) fatty acids such as Saccharomyces cerevisiae. Group II comprised yeasts without C 18:3 fatty acid like Zygosaccharo- myces rouxii and Torulaspora delbrueckii, and group III included yeasts with C18:2 and C18:3 acids that belong, among others, to one of the following yeast genera: Pichia, Candida, Kluyveromyces or Cryptococcus. Species-speci¢c PCR primers were used for the rapid detection and identi¢cation of the most dangerous species a¡ecting fruit concentrate stability. The simpli¢ed protocol used consisted of PCR-ampli¢cation of conserved tracts in the ITS region of the rDNA unit, thus enabling the detection ofpotentially dangerous £ora such as Zygosaccharomyces species andT. delbrueckii in contaminated fruit concentrates. Results from PCR-typing were in full agreement with the fatty acid compositions of these species. The grouping of contaminant yeasts into threemain groups showed that fatty acid compositionmay be used to di¡erentiate yeasts according to their technological signi¢cance.Yeasts isolated in thiswork as being most dangerous to product stability belong to either group II ( Z. rouxii and T. delbrueckii) or group I (Saccharomyces spp.). Group III was comprised of several species regarded as indicators of de¢ciencies in `good manufacturing practices'.Thus, each of the groups delineated may be considered to be a zymological indicator of technological signi¢cance.The conjugation of fatty acid pro¢les with PCR-typing methods may be used as a rapid detection system for contaminant yeasts. The fatty acid pro¢les provide a preliminary identi¢cation of yeasts potentially dangerous to product stability present within 48 h. of isolation. Whereas the PCR-typing method is mainly used to confirm isolate identity, when required, after the initial diagnosis has been performed, over a period of 4 h

From subdiffusion to superdiffusion of particles on solid surfaces

We present a numerical and partially analytical study of classical particles obeying a Langevin equation that describes diffusion on a surface modeled by a two dimensional potential. The potential may be either periodic or random. Depending on the potential and the damping, we observe superdiffusion, large-step diffusion, diffusion, and subdiffusion. Superdiffusive behavior is associated with low damping and is in most cases transient, albeit often long. Subdiffusive behavior is associated with highly damped particles in random potentials. In some cases subdiffusive behavior persists over our entire simulation and may be characterized as metastable. In any case, we stress that this rich variety of behaviors emerges naturally from an ordinary Langevin equation for a system described by ordinary canonical Maxwell-Boltzmann statistics

Investigation of pharmaceutical metabolites in environmental waters by LC-MS/MS

Pharmaceuticals, once ingested, are commonly metabolized in the body into more polar and soluble forms. These compounds might not be completely removed in the wastewater treatment plants and consequently being discharged into the aquatic ecosystem. In this work, a multi-class sensitive method for the analysis of 21 compounds, including 7 widely consumed pharmaceuticals and 14 relevant metabolites, has been developed based on the use of UHPLC-MS/MS in selected reaction monitoring (SRM) mode. The method was validated in six surface waters (SW) and six effluent wastewaters (EWW) at realistic concentration levels that can be found in waters. The optimized method was applied to the analysis of different types of water samples (rivers, lakes and effluent wastewater), detecting nearly all the parent compounds and metabolites investigated in this work. This fact illustrates that not only pharmaceuticals but also their metabolites are commonly present in these types of waters. Analytical research and monitoring programs should be directed not only towards parent pharmaceuticals but also towards relevant metabolites to have a realistic overview of the impact of pharmaceuticals in the aquatic environment

OBJETIVOS DE PRÁCTICAS ASISTENCIALES EN LA UNIDAD DE URGENCIAS HOSPITALARIA. PERCEPCIÓN DEL ALUMNADO SOBRE SU CUMPLIMIENTO.

El objetivo de este trabajo se centra en medir el aprendizaje de determinadas técnicas, la aportación de los seminarios impartidos, las preferencias del alumno en cuanto a su ubicación y el grado de satisfacción dentro de la unidad en las prácticas asistenciales de un grupo de 25 estudiantes de enfermería de tercer curso, correspondiente al curso 2002-2003, que realizaron sus prácticas asistenciales (médico quirúrgica II) en una unidad de urgencias hospitalarias