RF electro-thermal modeling of LDMOSFETs for power-amplifier design

A new approach for the electro-thermal modeling of LDMOSFETs for power-amplifier design that bypasses pulsed-IVs and pulsed-RF measurements is presented in this paper. The existence of low-frequency dispersion in LDMOSFETs is demonstrated by comparing pulsed IVs with iso-thermal IVs. The modeling technique uses iso-thermal IV and microwave measurements to obtain the temperature dependence of small-signal parameters. Optimized tensor-product B-splines, which distribute knots to minimize fitting errors, are used to represent the small-signal parameters and extract the large-signal model as a function of voltages and temperature. The model is implemented on ADS and is verified by simulating and measuring the power harmonics and IMD large-signal performance of a power amplifier. The impact on the model of temperature-dependent drain and gate charge is investigated. The presented model is found to compare well and, in some cases, exceed the existing MET model for LDMOSFETs     

Lobular carcinoma of the breast: cytological features supporting the diagnosis of lobular cancer

Lobular carcinomas have a distinct natural history with a better response to endocrine therapy and a higher incidence of local recurrence and are more often bilateral. The cytological diagnosis of lobular carcinoma permits a discriminating therapeutic approach with pre-operative Tamoxifen, more generous resection margins, and assessment of the contralateral breast. The cytological features of lobular cancer however are not well defined and the low cell yield from such neoplasms can result in a high false negative rate. To determine whether we could improve the pre-operative diagnosis, we reviewed the cytological features of 112 lobular carcinomas. They had small uniform sized nuclei with irregular outlines and inconspicuous nucleoli. The degree of dissociation was similar to duct carcinomas and the incidence of inadequate aspirates was no higher. We found no features that confidently diagnosed lobular cancer or its sub-types. However, using a combination of features, typing of lobular cancer on aspirated material is possible and should be attempted.     

High-performance liquid chromatographic determination of angiotensin II receptor antagonists in human plasma and urine. I. DuP 532 (L-694,492)

A sensitive reversed-phase high-performance liquid chromatographic method with ultraviolet detection was developed for the analysis of a new angiotensin II receptor antagonist, DuP 532 (L-694,492), in human plasma and urine. The analyte and internal standard are extracted from plasma and urine at a pH between 3.3 to 3.6 by liquid-liquid extraction and analyzed on a C6 column with ultraviolet detection at 254 nm. The mobile phase is composed of acetonitrile and phosphate buffer at pH 2.5. The limits of quantification are 6 and 7.5 ng/ml for plasma and urine, respectively.     

Age-related differences in the temporal and spatial regulation of matrix metalloproteinases (MMPs) in normal skin and acute cutaneous wounds of healthy humans

Despite the association of increasing age with chronic wound-healing disorders and an impaired rate of healing of acute cutaneous wounds, the role of matrix metalloproteinases (MMPs) is unknown. To determine the spatial and temporal patterns and activities of MMP-1, -2, -3 and -9, 132 healthy humans aged between 19 and 96 years underwent 4-mm punch biopsies followed by wound excision between day 1 and day 180 post-wounding. Wounds showed an age-related increase in MMP-2 and MMP-9 immunostaining from day 3; this was associated with degradation of gelatin as shown by zymograms and with increased proteinase activity as shown by azocoll assays. Distinct spatial localisations for each MMP were observed: MMP-2 was found in epidermal structures; MMP-9 was observed in inflammatory cells up to day 21; MMP-1 was localised to keratinocytes at the wound margin. Normal old skin showed pro-MMP-2 bands on zymography and increased MMP-2 immunostaining. These results indicate that: (1) intrinsic ageing is associated with the up-regulation of MMPs previously associated with chronic wound healing; (2) wound-tissue proteinases are essentially active up to day 21 postwounding; and (3) intrinsic ageing may predispose to tissue breakdown disorders because of MMP-2 up-regulation in normal skin.