Neural-Based Nonlinear Device Models for Intermodulation Analysis

A new procedure to learn a nonlinear model together with its derivative parameters using a composite neural network is presented.So far neural networks have never been used to extract large-signal device model accounting for distortion parameters.Applying this method to FET devices leads to nonlinear models for current- voltage functions which allow improved prediction of weak and mildly device nonlinearities in the whole bias region. The resulting models have demonstrated to be suitable for both small-signal and large-signal analyses,including intermodulation distortion prediction

Theoretical and experimental assessment of the non-linear scattering functions for the cad of non-linear microwave circuits

The Non-Linear Scattering Functions have been theoretically defined and experimentally measured for the linear-equivalent design of non-linear circuits in arbitrary large signal conditions. Non-linear measures and simulations have been compared, with good agreement. Linear CAD concepts can therefore be extended to non-linear circuits in a rigorous way

Can Ptilinopus greyii (Columbidae) Disperse Seeds in New Caledonia’s Dry Forests?

v. ill. 23 cm.QuarterlyConservation of endangered habitats of South Pacific islands is partially dependent on activity of seed dispersers. In consuming fruits, animals can spread seeds from parent plants to distant sites, thus contributing to plant regeneration and colonization of new sites. In the dry forests of New Caledonia, the red-bellied fruit-dove, Ptilinopus greyii, is a potential disperser of many fleshyfruited species. Trials with a captive bird showed that gut passage enhanced seed germination for Diospyros fasciculosa and Mimusops elengi but not for Vitex cf. collina, compared with whole fruits. Gut passage did not shorten duration of seed dormancy, which is consistent with evidence of a simple deinhibition effect for D. fasciculosa and M. elengi. Minimum Retention Time (MRT) of seeds in the gut differed significantly between the three tree species, from a mean of 17.4 min for D. fasciculosa to a mean of 52.4 min for M. elengi. These times are longer than observed foraging times in fruiting trees, potentially making this fruit-dove an effective seed disperser

Low-Bias-Complexity Ku-band GaN MMIC Doherty Power Amplifier

This paper present a two-stage Doherty power amplifier designed to maximize the efficiency at 6 dB back-off while minimizing the complexity in terms of bias voltages. The amplifier has been manufactured on a GaN-SiC 150 nm monolithic microwave integrated circuit technology. The fabricated chip, measured in continuous wave conditions, maintains a linear gain higher than 13 dB, a saturated output power in excess of 34 dBm, with a power-added efficiency higher than 20% both at saturation and at 6 dB output back-off, over the 14.5 GHz-17.25 GHz band, favorably comparing with the present state of the art for similar applications

Benefits on coronary restenosis from elective paclitaxel-eluting stent implantation in patients aged 75 years and older

OBJECTIVE: Elderly patients are increasingly referred for revascularisation yet have been underrepresented in some large clinical trials. Although the advent of drug-eluting stents has dramatically reduced clinical events related to restenosis, older age remains one of the most important correlates of adverse outcome, even after an elective percutaneous coronary intervention (PCI). We sought to evaluate the impact of paclitaxel-eluting stents on coronary restenosis in elderly patients undergoing elective PCI. METHODS: Patients undergoing successful elective PCI with stenting of de novo coronary artery lesions were identified and screened for participation in this study. All patients included in our analysis were divided into two cohort groups: patients aged or=75 years (elderly cohort). We evaluated the six-month incidence of target lesion revascularisation (TLR) and major adverse cardiac events, which included TLR, death and myocardial infarction. RESULTS: A total of 171 (58 aged >or=75 years) consecutive patients were enrolled in the study. At six months, TLR rate was similar in both groups [1.77 vs. 1.72%, odds ratio (OR) 0.97, 95% confidence interval (CI) 0.08-10.9, P = 0.98, in the younger and elderly group, respectively]. Even the rate of major adverse cardiac events was comparable between the two groups (7.96 vs. 8.62%, OR 1.09, 95% CI 0.34-3.41, P = 0.88, in the younger and elderly group, respectively). Also the angiographic restenosis rates were comparable between patients or=75 years (4.42 vs. 3.46%, P = 0.76). CONCLUSIONS: After elective paclitaxel-eluting stent implantation, there is no difference in coronary restenosis in younger and elderly patients, suggesting an age-independent efficacy

System Level Analysis of Millimetre-wave GaN-based MIMO Radar for Detection of Micro Unmanned Aerial Vehicles

The detection of Unmanned Aerial Vehicles (UAVs) of micro/nano dimensions, is becoming a hot topic, due to their large diffusion, and represents a challenging task from both the system architecture and components point of view. The Frequency Modulated Continuous Wave (FMCW) radar architecture in a Multi-Input Multi-Output configuration has been identified as the most suitable solution for this purpose, due to both its inherent short-range detection capability and compact implementation. This paper describes the operation and technology challenges inherent to the development of a millimeter-wave FMCW MIMO radar for small UAVs detection. In particular it analyzes the sub-systems specifications and the expected system performance with respect to a chip set designed and developed in GaN at 37.5 GHz applications

Gradient optimization of RF amplifiers for digital communications

A gradient optimization methodology for use with nonlinear envelope simulation is presented. Emphasis is placed on efficient evaluation of cost function gradients. To this end, an envelope sensitivity equation is derived and methods for its efficient solution are proposed. In the case of circuits of moderate size, the solution of the sensitivity equation is shown to be simple and inexpensive. The more troublesome case of larger circuits is treated by a novel application of a recently developed iterative linear equation solver. The result is a general-purpose, rigorous optimization methodology for the fine tuning of gain, adjacent channel power, power efficiency, and related performance measures in radio frequency (RF) amplifiers for digital communications. As an illustrative example, the optimization of a feedforward-linearized power amplifier is presented. © 2000 John Wiley & Sons, Inc. Int J RF and Microwave CAE 10, 353–365, 2000.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/35228/1/4_ftp.pd

postoperative mr imaging of spontaneous transdural spinal cord herniation expected findings and complications

BACKGROUND AND PURPOSE: Spontaneous transdural spinal cord herniation is no longer a rare cause of myelopathy. The high frequency of diagnoses has led to an increase in the number of surgical procedures. The purpose of this study was to describe the spectrum of postoperative MR imaging findings concerning spontaneous transdural spinal cord herniation and to provide a practical imaging approach for differentiating expected changes and complications after an operation. MATERIALS AND METHODS: We retrospectively reviewed MR images from 12 patients surgically treated for spontaneous transdural spinal cord herniation. Surgery comprised either dural defect enlargement or duraplasty procedures. Postoperative follow-ups included at least 3 (early, intermediate, late) MR imaging studies. MR images were analyzed with respect to 3 spinal compartments: intradural intramedullary, intradural extramedullary, and extradural. The meaning and reliability of changes detected on MR images were related to their radiologic and clinical evolution with time. RESULTS: Spinal cord realignment has been stable since the early study, whereas spinal cord signal and thickness evolved during the following scans. Most extramedullary and extradural changes gradually reduced in later MR images. Three patients treated with dural defect enlargements experienced the onset of new neurologic symptoms. In those patients, late MR images showed extradural fluid collection and the development of pial siderosis. CONCLUSIONS: Our findings demonstrate the spectrum of postoperative imaging findings in spontaneous transdural spinal cord herniation. Spinal cord thickness and signal intensity continued to evolve with time; most extramedullary postsurgical changes became stable. Changes observed in later images may be suggestive of complications

Estado de avance de las investigaciones arqueológicas en el sitio Empalme Querandíes 1 (centro de la subregión Pampa Húmeda, Provincia de Buenos Aires)

The aim of this article is to present the first results of an archaeological research performed at the site Empalme Querandies 1 (centre of the Humid Pampas sub-region, province of Buenos Aires). Considering a multidisciplinary approach, different types of analyses were carried out (geoenvironmental, chronology, taphonomy, subsistence, and technological trends). Stratigraphic and taphonomic studies suggest that the assemblage has a low integrity and resolution, covering different occupation events corresponding to the early Late Holocene (ca. 3100 to 2000 years BP). Faunal analyses indicate that the guanaco, the pampean deer, the greater rhea, and four armadillo species were part of the diet. Moreover, bone remains of the first two species were also used as raw material to manufacture tools. The study of the lithic assemblage shows that orthoquartzite and chert are both well represented, but there are variations in the objectives of production and in the strategies associated with their use. In the case of the pottery, undecorated as well as geometrical decorated sherds were recovered. Finally, the diverse sorts of studies indicate that part of the occupations at this multicomponent site would be related to loci of multiple activities of base camps.El objetivo de este trabajo es presentar el estado de avance de las distintas líneas de evidencia (geoambiental, cronología, tafonomía, subsistencia y tendencias tecnológicas) obtenidas a partir de las investigaciones arqueológicas llevadas a cabo en el sitio Empalme Querandíes 1 (centro de la subregión Pampa Húmeda, provincia de Buenos Aires). Los estudios estratigráficos y tafonómicos sugieren que el contexto presenta una baja integridad y resolución, abarcando diferentes eventos de ocupación del Holoceno tardío inicial (entre ca. 3100-2000 años AP). El análisis faunístico evidencia que el guanaco, el venado de las pampas, el ñandú y cuatro especies de armadillos formaron parte de la dieta. Asimismo, los restos óseos de por lo menos las dos primeras especies fueron utilizados como materia prima para confeccionar instrumentos. Respecto del material lítico, las rocas mejor representadas son la ortocuarcita y la ftanita, observándose diferencias en los objetivos de producción y en las estrategias vinculadas con su utilización. En el caso de la cerámica, se registró la presencia de tiestos no decorados y decorados con motivos geométricos. Las distintas líneas de evidencia sugieren que parte de las ocupaciones de este sitio multicomponente estarían vinculadas con loci de actividades múltiples de campamentos base

Internet-based caregiver support for Chinese Canadians taking care of a family member with alzheimer disease and related dementia

Author name used in this publication: Teresa ChiuVersion of RecordPublishe