A new method of threshold voltage extraction via MOSFET gate-to-substrate capacitance measurement

A new method to extract MOSFET's threshold voltage VT by measurement of the gate-to-substrate capacitance C-gb of the transistor is presented. Unlike existing extraction methods based on I-V data, the measurement of C-gb does not require de drain current to now between drain and source thus eliminating the effects of source and drain series resistance R-S/D, and at the same time, retains a symmetrical potential profile across the channel. Experimental and simulation results on devices with different sizes are presented to justify the proposed method.

Genetic consequences of sequential founder events by an island-colonizing bird

The importance of founder events in promoting evolutionary changes on islands has been a subject of long-running controversy. Resolution of this debate has been hindered by a lack of empirical evidence from naturally founded island populations. Here we undertake a genetic analysis of a series of historically documented, natural colonization events by the silvereye species-complex (Zosterops lateralis), a group used to illustrate the process of island colonization in the original founder effect model. Our results indicate that single founder events do not affect levels of heterozygosity or allelic diversity, nor do they result in immediate genetic differentiation between populations. Instead, four to five successive founder events are required before indices of diversity and divergence approach that seen in evolutionarily old forms. A Bayesian analysis based on computer simulation allows inferences to be made on the number of effective founders and indicates that founder effects are weak because island populations are established from relatively large flocks. Indeed, statistical support for a founder event model was not significantly higher than for a gradual-drift model for all recently colonized islands. Taken together, these results suggest that single colonization events in this species complex are rarely accompanied by severe founder effects, and multiple founder events and/or long-term genetic drift have been of greater consequence for neutral genetic diversity.

Alterations in Plasmodium falciparum genotypes during sequential infections suggest the presence of strain specific immunity

Many of the asexual stage Plasmodium falciparum proteins that are the targets of host protective responses are markedly polymorphic. The full repertoire of diversity is not defined for any antigen. Most studies have focused on the genes encoding merozoite surface proteins 1 and 2 (MSP1, MSP2). We explored the extent of diversity of some of the less studied merozoite surface antigens and analyzed the degree of complexity of malaria field isolates by deriving nucleotide sequences of several antigens. We have determined the genotype of apical membrane antigen 1 (AMA1) in a group of 30 field samples, collected over 29 months, from individuals living in an area of intense malaria transmission in Irian Jaya, identifying 14 different alleles. AMA1 genotyping was combined with previously determined MSP2 typing. AMA1 had the greatest power in distinguishing between isolates but methodological problems, especially when mixed infections are present, suggest it is not an ideal typing target. MSP1, MSP3, and glutamate-rich protein genotypes were also determined from a smaller group of samples, and all results were combined to derive an extended antigenic haplotype. Within this subset of 10 patients, nine different genotypes could be discerned; however, five patients were all infected with the same strain. This strain was present in individuals from two separate villages and was still present 12 months later. This strain was predominant at the first time point but had disappeared at the fourth time point. This significant change in malaria genotypes could be due to strain-specific immunity developing in this population.

Dopant extraction from scanning capacitance microscopy measurements of p-n junctions using combined inverse modeling and forward simulation

This article proposes a more accurate approach to dopant extraction using combined inverse modeling and forward simulation of scanning capacitance microscopy (SCM) measurements on p-n junctions. The approach takes into account the essential physics of minority carrier response to the SCM probe tip in the presence of lateral electric fields due to a p-n junction. The effects of oxide fixed charge and interface state densities in the grown oxide layer on the p-n junction samples were considered in the proposed method. The extracted metallurgical and electrical junctions were compared to the apparent electrical junction obtained from SCM measurements. (C) 2002 American Institute of Physics.

Preliminary characterisation and extraction of anterior adhesive secretion in monogenean (platyhelminth) parasites

Secreted anterior adhesives, used for temporary attachment to epithelial surfaces of fishes (skin and gills) by some monogenean (platyhelminth) parasites have been partially characterised. Adhesive is composed of protein. Amino acid composition has been determined for seven monopisthocotylean monogeneans. Six of these belong to the Monocotylidae and one species, Entobdella soleae (van Beneden et Hesse, 1864) Johnston, 1929, is a member of the Capsalidae. Histochemistry shows that the adhesive does not contain polysaccharides, including acid mucins, or lipids. The adhesive before secretion and in its secreted form contains no dihydroxyphenylalanine (dopa). Secreted adhesive is highly insoluble, but has a soft consistency and is mechanically removable from glass surfaces. Generally there are high levels of glycine and alanine, low levels of tyrosine and methionine, and histidine is often absent. However, amino acid content varies between species, the biggest differences evident when the monocotylid monogeneans were compared with E. soleae. Monogenean adhesive shows similarity in amino acid profile with adhesives from starfish, limpets and barnacles. However, there are some differences in individual amino acids in the temporary adhesive secretions of, on the one hand, the monogeneans and, on the other hand, the starfish and limpets. These differences may reflect the fact that monogeneans, unlike starfish and barnacles, attach to living tissue (tissue adhesion). A method of extracting unsecreted adhesive was investigated for use in further characterisation studies on monogenean glues.

Cloud-point extraction and preconcentration of cyanobacterial toxins (microcystins) from natural waters using a cationic surfactant

A new cloud-point extraction and preconcentration method, using a cationic, surfactant, Aliquat-336 (tricaprylyl-methy;ammonium chloride), his-been developed for the determination of cyanobacterial toxins, microcystins, in natural waters. Sodium sulfate was used to induce phase separation at 25 degreesC. The phase behavior of Aliquat-336 with respect to concentration of Na2SO4 was studied. The cloud-point system revealed a very high phase volume ratio compared to other established systems of nonionic, anionic, and cationic surfactants: At pH 6-7, it showed an outstanding selectivity in ahalyte extraction for anionic species. Only MC-LR and MC-YR, which are known to be predominantly anionic, were extracted (with averaged recoveries of 113.9 +/- 9% and 87.1 +/- 7%, respectively). MC-RR, which is likely to be amphoteric at the above pH range, was. not cle tectable in.the extract. Coupled to HPLC/UV separation and detection, the cloud-point extraction method (with 2.5 mM Aliquat-336 and 75 mM Na2SO4 at 25 degreesC) offered detection limits of 150 +/- 7 and 470 +/- 72 pg/mL for MC-LR and MC-YR, respectively, in 25 mL of deionized water. Repeatability of the method was 7.6% for MC-LR and 7.3% for MC-YR: The cloud-point extraction process can be. completed within 10-15 min with no cleanup steps required. Applicability of the new method to the determination of microcystins in real samples was demonstrated using natural surface waters, collected from a local river and a local duck pond spiked with realistic. concentrations of microcystins. Effects of salinity and organic matter (TOC) content in the water sample on the extraction efficiency were also studied.

Surgical extraction of transplanted adult Dirofilaria immitis in cats

A jugular venotomy technique was developed to attempt extraction of Dirofilaria immitis in cats. Seven cats were first examined by cardiac ultrasound to establish the location of adult D. immitis that had been inserted by jugular venotomy. The efficiency of an extractor catheter in surgically removing filariae similarly inserted into 13 experimental cats was then assessed. A mean extraction success rate of 96% was achieved. This technique would seem to be worthy of clinical use provided the filariae are in the right atrial area.

A model to investigate hepatic extraction of oxygen during anaesthesia in the dog

Measurement of hepatic oxygen extraction was performed on six healthy Greyhound dogs over a two hour period. The Greyhounds were anaesthetised and a right subcostal surgical incision performed. Ultrasonic flow transducers were used to measure flow rate in the hepatic artery and the portal vein. The blood oxygen tensions in arterial blood and in the portal and hepatic veins were also measured. Hepatic oxygen extraction remained stable throughout the study, despite a steady decline in arterial blood pressure. The methodology described in this study provides a direct measure of oxygen uptake by the liver in the dog and could readily be used to investigate hepatic uptake of drugs. (C) 2003 Elsevier Ltd. All rights reserved.

Ocular scanning and perceptual size distortion in hemispatial neglect: effects of prism adaptation and sequential stimulus presentation

When asked to compare two lateralized shapes for horizontal size, neglect patients often indicate the left stimulus to be smaller. Gainotti and Tiacci (1971) hypothesized that this phenomenon might be related to a rightward bias in the patients' gaze. This study aimed to assess the relation between this size underestimation and oculomotor asymmetries. Eye movements were recorded while three neglect patients judged the horizontal extent of two rectangles. Two experimental manipulations were performed to increase the likelihood of symmetrical scanning of the stimulus display. The first manipulation entailed a sequential, rather than simultaneous presentation of the two rectangles. The second required adaptation to rightward displacing prisms, which is known to reduce many manifestations of neglect. All patients consistently underestimated the left rectangle, but the pattern of verbal responses and eye movements suggested different underlying causes. These include a distortion of space perception without ocular asymmetry, a failure to view the full leftward extent of the left stimulus, and a high-level response bias. Sequential presentation of the rectangles and prism adaptation reduced ocular asymmetries without affecting size underestimation. Overall, the results suggest that leftward size underestimation in neglect can arise for a number of different reasons. Incomplete leftward scanning may perhaps be sufficient to induce perceptual size distortion, but it is not a necessary prerequisite.

Automatic segmentation and 3D feature extraction of protein aggregates in Caenorhabditis Elegans

In the last years, it has become increasingly clear that neurodegenerative diseases involve protein aggregation, a process often used as disease progression readout and to develop therapeutic strategies. This work presents an image processing tool to automatic segment, classify and quantify these aggregates and the whole 3D body of the nematode Caenorhabditis Elegans. A total of 150 data set images, containing different slices, were captured with a confocal microscope from animals of distinct genetic conditions. Because of the animals’ transparency, most of the slices pixels appeared dark, hampering their body volume direct reconstruction. Therefore, for each data set, all slices were stacked in one single 2D image in order to determine a volume approximation. The gradient of this image was input to an anisotropic diffusion algorithm that uses the Tukey’s biweight as edge-stopping function. The image histogram median of this outcome was used to dynamically determine a thresholding level, which allows the determination of a smoothed exterior contour of the worm and the medial axis of the worm body from thinning its skeleton. Based on this exterior contour diameter and the medial animal axis, random 3D points were then calculated to produce a volume mesh approximation. The protein aggregations were subsequently segmented based on an iso-value and blended with the resulting volume mesh. The results obtained were consistent with qualitative observations in literature, allowing non-biased, reliable and high throughput protein aggregates quantification. This may lead to a significant improvement on neurodegenerative diseases treatment planning and interventions prevention

Ball Recovery in the Handball Tournament of the 2008 Beijing Olympic Games: Sequential Analysis of Positional Play as Used by the Spanish Team’s Defence

In sport there is a great need to obtain as much information as possible about the factors which affect the dynamics of play. This study uses sequential analysis and temporal patterns (T-patterns)to examine the evolution of defence (against an equal number of attackers)as used by the Spanish handball team at the Beijing 2008 Olympic Games. The aim is to help handball coaches (during their training and gathering of professional experience)to understand the importance of the structure of defensive systems. This can be achieved through observational processes that reveal the evolution and adaptation of these defensive systems according to different variables: the match score, the response of the opposing team and progress through the tournament.

Supercritical CO2 extraction of secondary metabolites from Agaricus blazei: experiments and modelling

The mycelium and young fruiting bodies of Agaricus blazei were submitted to supercritical CO2 extraction, in a modified commercial flow apparatus, at temperatures from 40 to 80 ºC, pressures up to 600 bar and CO2 flow-rates from 2.0 to 9.0 g.min-1. The best extraction conditions of secondary metabolites, whereby the degree of solubilization (g extract/100 g of fungi) is the highest, was obtained with pure CO2 at 400 bar, 70 ºC and a CO2 flow rate of 5.7g.min-1. The extract in that conditions were analysed by GC-Ms. In order to increase the extraction yield of secondary metabolites, which are mostly present in glycolipid fractions, a polar compound (ethanol) was used as co-solvent in the proportions of 5 and 10 % (mol/mol). The presence of ethanol increased the yield when compared with the extraction with pure CO2. Moreover, a simple model was applied to the supercritical CO2 extraction of secondary metabolites from Agaricus blazei.

Herbicidal activity of volatiles from coriander, winter savory, cotton lavender, and thyme isolated by hydrodistillation and supercritical fluid extraction

The volatiles from Coriandrum sativum L., Satureja montana L., Santolina chamaecyparissus L., and Thymus vulgaris L. were isolated by hydrodistillation (essential oil) and supercritical fluid extraction (volatile oil). Their effect on seed germination and root and shoot growth of the surviving seedlings of four crops (Zea mays L., Triticum durum L., Pisum sativum L., and Lactuca sativa L.) and two weeds (Portulaca oleracea L. and Vicia sativa L.) was investigated and compared with those of two synthetic herbicides, Agrocide and Prowl. The volatile oils of thyme and cotton lavender seemed to be promising alternatives to the synthetic herbicides because they were the least injurious to the crop species. The essential oil of winter savory, on the other hand, affected both crop and weeds and can be appropriate for uncultivated fields.