Nanometer-scale InGaAs Field-Effect Transistors for THz and CMOS technologies

Integrated circuits based on InGaAs Field Effect Transistors are currently in wide use in the RF front-ends of smart phones and other mobile platforms, wireless LANs, high data rate fiber-optic links and many defense and space communication systems. InGaAs ICs are also under intense research for new millimeter-wave applications such as collision avoidance radar and gigabit WLANs. InGaAs FET scaling has nearly reached the end of the road and further progress to propel this technology to the THz regime will require significant device innovations. Separately, as Si CMOS faces mounting difficulties to maintain its historical density scaling path, InGaAs-channel MOSFETs have recently emerged as a credible alternative for mainstream logic technology capable of scaling to the 10 nm node and below. To get to this point, fundamental technical problems had to be solved though there are still many challenges to be addressed before the first non-Si CMOS technology becomes a reality. The intense research that this exciting prospect is generating is also reinvigorating the prospects of InGaAs FETs to become the first true THz electronics technology. This paper reviews progress and challenges of InGaAs-based FET technology for THz and CMOS.Focus Center Research Program. Center for Materials, Structures and DevicesIntel CorporationUnited States. Army Research LaboratorySemiconductor Research Corporatio

Ortodoxia y heterodoxia en el estudio de la escultura románica española: estado de la cuestión

Revisión de la investigación sobre la escultura románica española de hacia 1070-1200. Los problemas metodológicos analizados incluyen la definición de "románico", las fuentes locales e importadas para la escultura arquitectónica de la Península Ibérica, el impacto del patronazgo y de la peregrinación a Santiago de Compostela, la disyunción entre documento y monumentos, y las cronologías dispares de los monumentos más significativos de la Península. Los edificios examinados incluyen León, Jaca, Frómista, Compostela, Silos, Pamplona, San Juan de la Peña y Zaragoza. Igualmente se han tenido en cuenta estudios iconográficos y métodos adecuados a las especiales circunstancias de la España medieval.A review of the scholarship of Spanish Romanesque sculpture ca. 1070-1200. Methodological problems covered include the definition of "Romanesque", the local and imported sources for architectural sculpture in the Iberian Península, the impact of patronage and of the pilgrimage to Santiago de Compostela, the disjuction of the documents and monuments, and the widely varying chronologies for the Peninsula's most significant sites. Monuments discussed include León, Jaca, Frómista, Compostela, Silos, Soria, Pamplona, San Juan de la Peña, and Zaragoza. Iconographic studies and methods appropriate for the special circumstances of medieval Spain are also considered

The High-Electron Mobility Transistor at 30: Impressive Accomplishments and Exciting Prospects

2010 marked the 30th anniversary of the High-Electron Mobility Transistor (HEMT). The HEMT represented a triumph for the, at the time, relatively new concept of bandgap engineering and nascent molecular beam epitaxy technology. The HEMT showcased the outstanding electron transport characteristics of two-dimensional electron gas (2DEG) systems in III-V compound semiconductors. In the last 30 years, HEMTs have been demonstrated in several material systems, most notably AlGaAs/GaAs and AlGaN/GaN. Their uniqueness in terms of noise, power and high frequency operation has propelled HEMTs to gain insertion in a variety of systems where they provide critical performance value. 2DEG systems have also been a boon in solid-state physics where new and often bizarre phenomena have been discovered. As we look forward, HEMTs are uniquely positioned to expand the reach of electronics in communications, signal processing, electrical power management and imaging. Some of the most exciting prospects in the near future for HEMT-like devices are those of GaN for high voltage power management and III-V CMOS to give a new lease on life to Moore’s Law. This paper briefly reviews some highlights of HEMT development in the last 30 years in engineering and science. It also speculates about potential future applications

Studies of hexahelicene bonded phases for the HPLC resolution of enantiomers

The thesis presents a review of the literature on the HPLC resolution of enantiomers using chiral stationary phases and discusses the mechanisms of separation and the utility of these phases. The synthesis and chemical, chiroptical and spectroscopic properties of helicenes are also reviewed and the potential utility of helicene-based for the HPLC resolution of enantiomers is discussed. The work carried out involved the preparation of a hexahelicene-based chiral stationary phase and demonstrations of its utility for the resolution of chiral analytes. This phase was chemically bonded rather than physically coated, in order to make it stable to hydrolysis and solvent stripping, and therefore to permit its employment with a wide range of mobile phases. This thesis describes the synthesis of hexahelicen-7-ylacetic acid methyl ester, including confirmation of the structure of the key synthetic intermediates by spectroscopic analysis, and the investigation of several proceduresfor the resolution of hexahelicen-7-ylacetic acid methyl ester into its enantiomers, one of which enabled around 100 mg amounts of each of (+) and (-) enantiomers of hexahelicen-7-ylacetic acid to be obtained in highly chemically and optically pure form. The thesis also gives an account of several synthetic approaches to covalently bonding of the chiral selector (hexahelicen-7-ylacetic acid) to a modified silica stationary phase. Chiral stationary phases were prepared from each of the enantiomers in sufficient amount to permit the packing of analytical columns of these phases. Chiral solutes containing nitroaryl functionalities were synthesised to investigate the chiral resolving power of these novel phases. Adequate separations were obtained with both chiral stationary phases and, as anticipated, the eluting order of chiral analytes was reversed between the (+) and (-) stationary phases. The work demonstrated the utility of these columns for the resolution of nitroaryl-containing chiral analytes

Study of lifetimes of nuclear excited states near the N=20 island of inversion using the Doppler Shift Attenuation Method

openIn the region along the neutron-rich N = 20 shell closure, the ground-state structure of certain isotopes is known to be dominated by intruder configurations. In these configurations, neutrons occupy states above the N = 20 shell gap, while leaving vacancies in the shell below. This area on the nuclear chart is known as the N = 20 island of inversion. The trend extends to nearby nuclei, where sets of intruder states have been found among their excited states. Lifetime measurements are commonly used to unravel the nature and properties of nuclear states, as they are closely related to transition probabilities. Comparing those to theoretical predictions, indirect information on the nuclear wave-functions can be extracted. This thesis provides a first-step analysis of an experiment which aims to investigate the interplay between spherical and intruder configurations in the low-lying states of isotopes on the boundary of the N = 20 island of inversion, namely 34Si and 35P. The AGATA High-Purity Germanium γ-tracking array was used in coincidence with the PRISMA high-acceptance magnetic spectrometer to detect the γ rays emitted in the decay of the states of interest. From the γ-ray energy spectrum measured, the Doppler Shift Attenuation Method was used to extract the associated lifetimes, expected to lie in the range from 30 to 100 fs. The analysis involved processing data from both detectors. In order to extract the lifetimes, the shapes of the peaks in the γ-ray energy spectrum were compared to those produced by a Monte Carlo GEANT4 simulation, adapted to mimic the experimental conditions. Doing so, it was possible to estimate the lifetime of the first 2+ state in 36S and provide a first preliminary lifetime estimation for the 3/2+ state of 35P.In the region along the neutron-rich N = 20 shell closure, the ground-state structure of certain isotopes is known to be dominated by intruder configurations. In these configurations, neutrons occupy states above the N = 20 shell gap, while leaving vacancies in the shell below. This area on the nuclear chart is known as the N = 20 island of inversion. The trend extends to nearby nuclei, where sets of intruder states have been found among their excited states. Lifetime measurements are commonly used to unravel the nature and properties of nuclear states, as they are closely related to transition probabilities. Comparing those to theoretical predictions, indirect information on the nuclear wave-functions can be extracted. This thesis provides a first-step analysis of an experiment which aims to investigate the interplay between spherical and intruder configurations in the low-lying states of isotopes on the boundary of the N = 20 island of inversion, namely 34Si and 35P. The AGATA High-Purity Germanium γ-tracking array was used in coincidence with the PRISMA high-acceptance magnetic spectrometer to detect the γ rays emitted in the decay of the states of interest. From the γ-ray energy spectrum measured, the Doppler Shift Attenuation Method was used to extract the associated lifetimes, expected to lie in the range from 30 to 100 fs. The analysis involved processing data from both detectors. In order to extract the lifetimes, the shapes of the peaks in the γ-ray energy spectrum were compared to those produced by a Monte Carlo GEANT4 simulation, adapted to mimic the experimental conditions. Doing so, it was possible to estimate the lifetime of the first 2+ state in 36S and provide a first preliminary lifetime estimation for the 3/2+ state of 35P

Factors affecting wheat nutritional value for broiler chickens

In Europe, broiler chickens are fed with balanced diets where the energy is mainly supplied by wheat. The feed industry considers wheat a moderately uniform raw material and therefore its energy content and nutrient digestibility are taken from feeding tables (tabulated values) and assigned to all wheat grains. However, all major wheat-producing countries report considerable variability in energy content of wheat which invalidates the assumption of uniformity among wheat grains and forces the industry to look for the factors responsible of the variation. This PhD has focused on the study of factors that affect the nutritional value of wheat for broiler chickens. After the literature review, few nutrient components of the wheat grain (starch and non-starch polysaccharides) where selected and deeper studied in different wheat cultivars fed to broiler chickens. Emphasis was put on the rate of wheat starch digestion by broiler chickens and its effect on broiler performance

The Intelligent Web

Many people are working on the Semantic Web with the main objective being to enhance web searches. Our proposal is a new research strategy based on the existence of a discrete set of semantic relations for the creation and exploitation of semantic networks on the web. To do so, we have defined in a previous paper (Álamo, Martínez, Jaén) the Rhetoric-Semantic Relation (RSR) based on the results of the Rhetoric Structure Theory. We formulate a general set of RSR capable of building discourse and making it possible to express any concept, procedure or principle in terms of knowledge nodes and RSRs. These knowledge nodes can then be elaborated in the same way. This network structure in terms of RSR makes the objective of developing automatic answering systems possible as well as any other type of utilities oriented towards the exploitation of semantic structure, such as the automatic production of web pages or automatic e-learning generation