Accurate substrate modelling of RF CMOS

The losses within the substrate of an RF IC can have significant effect on performance in a mixed signal application. in order to model substrate coupling accurately, it is represented by an RC network to account for both resistive and dielectric losses at high frequency (> 1 GHz). A small-signal equivalent circuit model of an RF IC inclusive of substrate parasitic effect is analysed in terms of its y-parameters and an extraction procedure for substrate parameters has been developed. By coupling the extracted substrate parameters along with extrinsic resistances associated with gate, source and drain, a standard BSIM3 model has been extended for RF applications. The new model exhibits a significant improvement in prediction of output reflection coefficient S-22 in the frequency range from 1 to 10 GHz in device mode of operation and for a low noise amplifier (LNA) at 2.4 GHz. Copyright (C) 2006 John Wiley & Sons, Ltd.

Extrinsic parameter extraction and RF modelling of CMOS

An analytical approach for CMOS parameter extraction which includes the effect of parasitic resistance is presented. The method is based on small-signal equivalent circuit valid in all region of operation to uniquely extract extrinsic resistances, which can be used to extend the industry standard BSIM3v3 MOSFET model for radio frequency applications. The verification of the model was carried out through frequency domain measurements of S-parameters and direct time domain measurement at 2.4 GHz in a large signal non-linear mode of operation. (C) 2003 Elsevier Ltd. All rights reserved.

Investigation of an electron string ion source with field emission cathode

The string mode of operation for an electron beam ion source uses axially oscillating electrons in order to reduce power consumption, also simplifying the construction by omitting the collector with cooling requirements and has been called electron string ion source (ESIS). We have started a project (supported by INTAS and GSI) to use Schottky field emitting cathode tips for generating the electron string. The emission from these specially conditioned tips is higher by orders of magnitude than the focused Brillouin current density at magnetic fields of some Tesla and electron energies of some keV. This may avoid the observed instabilities in the transition from axially oscillating electrons to the string state of the electron plasma, opening a much wider field of possible operating parameters for an ESIS. Besides the presentation of the basic features, we emphasize in this paper a method to avoid damaging of the field, emission tip by backstreaming ions. (C) 2008 American Institute of Physics.

Comparison of biosensor platforms for surface plasmon resonance based detection of paralytic shellfish toxins

Paralytic shellfish poisoning (PSP) toxins are produced by certain marine dinoflagellates and may accumulate in bivalve molluscs through filter feeding. The Mouse Bioassay (MBA) is the internationally recognised reference method of analysis, but it is prone to technical difficulties and regarded with increasing disapproval due to ethical reasons. As such, alternative methods are required. A rapid surface plasmon resonance (SPR) biosensor inhibition assay was developed to detect PSP toxins in shellfish by employing a saxitoxin polyclonal antibody (R895). Using an assay developed for and validated on the Biacore Q biosensor system, this project focused on transferring the assay to a high-throughput, Biacore T100 biosensor in another laboratory. This was achieved using a prototype PSP toxin kit and recommended assay parameters based on the Biacore Q method. A monoclonal antibody (GT13A) was also assessed. Even though these two instruments are based on SPR principles, they vary widely in their mode of operation including differences in the integrated mu-fluidic cartridges, autosampler system, and sensor chip compatibilities. Shellfish samples (n = 60), extracted using a simple, rapid procedure, were analysed using each platform, and results were compared to AOAC high performance liquid chromatography (HPLC) and MBA methods. The overall agreement, based on statistical 2 x 2 comparison tables, between each method ranged from 85% to 94.4% using R895 and 77.8% to 100% using GT13A. The results demonstrated that the antibody based assays with high sensitivity and broad specificity to PSP toxins can be applied to different biosensor platforms. (C) 2011 Elsevier B.V. All rights reserved.

The initial mode of action of copper on the cardiac physiology of the blue mussel, Mytilus edulis

Previous studies have shown that low levels of copper (down to 0.8 muM) induce bradycardia in the blue mussel (Mytilus edulis) and that this is not caused by prolonged Valve closure. The aim of this study was to determine the precise mechanism responsible. To establish if copper was directly affecting heart cell physiology, recordings of contractions from isolated ventricular strips were made using an isometric force transducer, in response to copper concentrations (as CuCl2) ranging between 1 muM and 1 mM. Inhibition of mechanical activity only occurred at 1 mM copper, suggesting that the copper-induced bradycardia observed in whole animals cannot be attributed to direct cardiotoxicity. Effects of copper on the cardiac nerves were subsequently examined. Following removal of visceral ganglia (from where the cardiac nerves originate), exposure to 12.5 muM copper had no effect on the heart rate of whole animals. The effect of copper on the heart rate of mussels could not be abolished by depletion of the monoamine content of the animal using reserpine. However, pre-treatment of the animals with alpha -bungarotoxin considerably reduced the sensitivity of the heart to copper. These results indicated that the influence of copper on the heart of M. edulis might be mediated by a change in the activity of cholinergic nerves to heart. In the final experiments, mussels were injected with either benzoquinonium or D-tubocurarine, prior to copper exposure, in an attempt to selectively block the inhibitory or excitatory cholinoreceptors of the heart. Only benzoquinonium decreased the susceptibility of the heart to copper, suggesting that copper affects the cardiac activity of blue mussels by stimulating inhibitory cholinergic nerves to the heart. (C) 2001 Elsevier Science B.V. All rights reserved.

Monochloroacetic acid and 60% salicylic acid as a treatment for simple plantar warts:effectiveness and mode of action

Monochloroacetic acid crystals and 60% salicylic acid ointment was found to be more effective than placebo as a treatment for simple plantar warts in a double blind study on 57 patients. Nineteen (66%) patients in the active treatment group compared with five (18%) patients in the placebo group were cured after 6 weeks (P = 0.002). The active treatment was associated with a significantly higher cure rate 6 months after entry (P = 0.04). Treatments were well tolerated. IgG or IgM antibodies or both to human papilloma virus (HPV) types 1 or 2 or both were detected significantly more frequently in the actively treated group 6 weeks after entry (P = 0.0005). Twelve (50%) patients considered to be cured had no detectable secondary immune response. Our results suggest that cure does not depend primarily on the humoral system but rather on mechanical destruction of wart tissue, or occurs as a result of cell mediated immunity.

Mode of insertion of the abductor hallucis muscle in human feet and its arterial supply

The abductor hallucis flap is commonly used as a pedicled flap (distally or proximally based) in the management of ankle, heel, and mid-foot lesions, where it is ideally used for closing defects. This study investigates the anatomical details of this muscle regarding its various forms of insertion and its arterial supply in 15 cadaveric feet. Four types of insertion could be distinguished: type A, insertion at the proximal phalanx of the big toe (46.7%); type B, insertion by two slips into the base of the proximal phalanx and the sesamoid bone (33.3%); type C, insertion at the sesamoid bone (6.7%); And type D, the insertion is divided into superficial tendinous and deep fleshy parts which are attached to the base of the proximal phalanx and to the metatarsophalangeal joint capsule of the big toe, respectively (13.3%). As regards the arterial supply, three patterns were noticed: pattern A (40%) where the medial plantar artery (MPA) is divided into superficial and deep branches that supplied the muscle; pattern B (53.3%) where the MPA failed to produce a deep branch but instead continued as the superficial branch supplying the two ends of the muscle; and pattern C (6.6%) where the MPA continued as a deep branch supplying the muscle. A superficial branch of MPA provided a branch to the abductor hallucis muscle from its proximal part. In two specimens (13.3%), the lateral plantar artery shared in the supply of the most proximal part of the muscle. These results can be useful in determining the appropriate flap design based on the abductor hallucis type of insertion and the pattern of its arterial supply in the patients.

Mode of prostate cancer detection is associated with the psychological wellbeing of survivors: results from the PiCTure study

Purpose: Many men with prostate cancer are asymptomatic, diagnosed following prostate specific antigen (PSA) testing. We investigate whether mode of detection, i.e. ‘PSA detected’ or ‘clinically detected’, was associated with psychological wellbeing among prostate cancer survivors. Methods: A cross-sectional postal questionnaire was administered in 2012 to 6559 prostate cancer (ICD10 C61) survivors up to 18 years post-diagnosis, identified through population-based cancer registries in Ireland. Psychological wellbeing was assessed using the Depression Anxiety Stress Scale-21. Logistic regression was used to investigate associations between mode of detection and depression, anxiety and stress, adjusting for socio-demographic and clinical confounders. Results: The response rate was 54 % (3348/6262). Fifty-nine percent of survivors were diagnosed with asymptomatic PSA-tested disease. Prevalence of depression (13.8 vs 20.7 %; p < 0.001), anxiety (13.6 vs 20.9 %; p < 0.001) and stress (8.7 vs 13.8 %; p < 0.001) were significantly lower among survivors diagnosed with PSA-detected, than clinically detected disease. After adjusting for clinical and socio-demographic factors, survivors with clinically detected disease had significantly higher risk of depression (odds ratio (OR) = 1.46 95 % CI 1.18, 1.80; p = 0.001), anxiety (OR = 1.36 95 % CI 1.09, 1.68; p = 0.006) and stress (OR = 1.43 95 % CI 1.11, 1.85; p = 0.006) than survivors with PSA-detected disease. Conclusions: These findings contribute to the ongoing debate on benefits and risks of PSA testing and may be considered by policy makers formulating population-based prostate cancer screening policies. The relatively high prevalence of negative psychological states among survivors means that a ‘risk-adapted approach’ should be implemented to screen survivors most at risk of psychological morbidity for psychological health, and mode of detection could be considered as a risk stratum.