A simple theory to predict the threshold voltage of short-channel IGFET's

A simple expression for the threshold voltage of an IGFET is derived from a charge conservation principle which geometrically takes into account two-dimensional edge effects. The expression is derived for zero drain voltage and is valid for short and long-channel lengths. The dependence of the threshold voltage on the source and drain diffusion depth, r_j, and channel length, L, is explicitly given. In the limit, L/r_j → ∞, the threshold voltage equation reduces to the familiar expression for the long-channel case.The theory is compared with the measured threshold voltages on IGFET's fabricated with 1·4, 3·8 and 7·4 μm channel lengths. The dependence of the threshold voltage under backgate bias voltages ranging from zero to breakdown agrees closely with the theory.     

A historical note on animal magnetism.

Describes the role played by Benjamin Franklin in the demise of animal magnetism research. Franklin served on a commission appointed by the French Academy of Sciences whose subsequent report failed to support the work of F. A. Mesmer and his disciple C. Deslon. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A direct method for cluster analysis

An algorithm based on a least-mean-square (LMS) criterion is presented. This algorithm partitions a multi-dimensional data set directly into a desired number of clusters. The result is compared favorably to existing methods in both performance and computational efficiency. An efficient method for determining a reasonable set of distributed initial cluster centers based on principal component analysis is also presented. This clustering algorithm is shown to converge to a unique minimum based on the LMS criterion and is demonstrated by digital computer simulation and applied to the analysis of vectorcardiograms.     

An Investigation of Negative Differential Resistance and Novel Collector–Current Kink Effects in SiGe HBTs Operating at Cryogenic Temperatures

In this paper, a new negative-differential-resistance (NDR) effect and a novel collector-current kink effect are investigated in the cryogenically operated SiGe heterojunction bipolar transistors (HBTs). Theory based on an enhanced positive-feedback mechanism associated with heterojunction barrier effect at deep cryogenic temperatures is proposed to explain both the observed NDR and the collector-current kink. The accumulated charge induced by the barrier effect acts at low temperatures to enhance the total collector-current, indirectly producing both phenomena. This theory is confirmed using the calibrated 2-D DESSIS simulations over temperature. These unique cryogenic effects also have significant impact on the ac performance of SiGe HBTs operating at high injection. Technology evolution plays an important role in determining the magnitude of the observed phenomena, and the scaling implications are addressed. In addition, the present NDR effect is also compared with previously reported NDR and hysteresis effects observed in highly scaled SiGe HBTs operating under forced-I_B-base bias. The input drive condition of the transistor during its use in circuits, either under pure forced-current bias or under pure forced-voltage bias, or more practically, somewhere in between, determines the magnitude of the observed NDR and is of potential concern for circuit designers and must be carefully modeled     

An efficient algorithm for superresolution in medium field imaging

In this paper, we study the problem of reconstruction of a high-resolution (HR) image from several blurred low-resolution (LR) image frames in medium field. The image frames consist of blurred, decimated, and noisy versions of a HR image. The HR image is modeled as a Markov random field (MRF), and a maximum a posteriori (MAP) estimation technique is used for the restoration. We show that with the periodic boundary condition, a HR image can be restored efficiently by using fast Fourier transforms. We also apply the preconditioned conjugate gradient method to restore HR images in the aperiodic boundary condition. Computer simulations are given to illustrate the effectiveness of the proposed approach. This research was conducted with support from the Army Research Office Grant DAAD 19-03-1-0261 and the National Science Foundation Grant CCF-0429481. Research supported in part by RGC Grant Nos. 7130/02P, 7046/03P, 7035/04P and 7035/04P and FRG/04-05/II-51.     

Understanding barriers to home‐based and self‐care in‐center hemodialysis

Despite superior outcomes and lower associated costs, relatively few patients with end‐stage renal disease undergo self‐care or home hemodialysis. Few studies have examined patient‐ and physician‐specific barriers to self‐care and home hemodialysis in the modern era. The degree to which innovative technology might facilitate the adoption of these modalities is unknown. We surveyed 250 patients receiving in‐center hemodialysis and 51 board‐certified nephrologists to identify key barriers to adoption of self‐care and home hemodialysis. Overall, 172 (69%) patients reported that they were “likely” or “very likely” to consider self‐care hemodialysis if they were properly trained on a new hemodialysis system designed for self‐care or home use. Nephrologists believed that patients were capable of performing many dialysis‐relevant tasks, including: weighing themselves (98%), wiping down the chair and machine (84%), clearing alarms during treatment (53%), taking vital signs (46%), and cannulating vascular access (41%), but thought that patients would be willing to do the same in only 69%, 34%, 31%, 29%, and 16%, respectively. Reasons that nephrologists believe patients are hesitant to pursue self‐care or home hemodialysis do not correspond in parallel or by priority to reasons reported by patients. Self‐care and home hemodialysis offer several advantages to patients and dialysis providers. Overcoming real and perceived barriers with new technology, education and coordinated care will be required for these modalities to gain traction in the coming years.     

POPULATION STRUCTURE IN THREE SPECIES OF CO‐DISTRIBUTED SALMONID FISHES IN THE PEACE RIVER AND TRIBUTARIES NEAR A MAJOR PROPOSED HYDROELECTRIC DEVELOPMENT IN NORTHEASTERN BRITISH COLUMBIA,CANADA

Dam construction and reservoir formation represent profound anthropogenic alterations to natural riverscapes, especially in terms of connectivity in migratory fishes. The Peace River in northeastern British Columbia (BC), Canada, is the largest river system in BC, home to 39 native fishes and currently has two major hydroelectric projects, and a third one (‘Site C’) is proposed. Three co‐distributed and migratory fishes, the bull trout (Salvelinus confluentus), Arctic grayling (Thymallus arcticus) and the mountain whitefish (Prosopium williamsoni) are key species in the Peace River ecologically and in terms of recreational fisheries. We examined microsatellite DNA variation in these species to assess genetic diversity, levels of population subdivision and connectivity to better understand potential impacts and to provide baseline information for subsequent monitoring. Expected heterozygosity and number of alleles averaged 0.65 and 7.7, 0.73 and 11.9, and 0.72 and 10.8 for bull trout (nine loci), Arctic grayling (10 loci) and mountain whitefish (10 loci), respectively. Estimates of the effective number of breeders (N_b) ranged from 35 to 255 for bull trout to over 3700 for Arctic grayling. Population subdivision (F_ST, θ) was 0.040, 0.063 and 0.023 in bull trout, Arctic grayling and mountain whitefish, respectively (all p < 0.001). Temporal differences within localities for all species accounted for <1% of total variation in allele frequencies. An estimated 6.2% (mountain whitefish), 4.6% (bull trout) and 8.8% (Arctic grayling) of fish samples were inferred (p < 0.05) to be immigrants to one locality from another locality. Our results suggest that connectivity amongst localities is important to successful completion of the life history of each species, the potential disruption of which will be a critical aspect of post‐development monitoring. Copyright © 2013 John Wiley & Sons, Ltd.     

Uncorrelated component analysis for blind source separation

The uncorrelated component analysis (UCA) of a stationary random vector process consists of searching for a linear transformation that minimizes the temporal correlation between its components. Through a general analysis we show that under practically reasonable and mild conditions UCA is a solution for blind source separation. The theorems proposed in this paper for UCA provide useful insights for developing practical algorithms. UCA explores the temporal information of the signals, whereas independent component analysis (ICA) explores the spatial information; thus UCA can be applied for source separation in some cases where ICA cannot. For blind source separation, combining ICA and UCA may give improved performance because more information can be utilized. The concept of single UCA (SUCA) is also proposed, which leads to sequential source separation.This work was supported in part by grants from the Research Grants Council of Hong Kong, grants HKU553/96M, HKU7036/97E, and HKUST776/96E.