High-gain, V-band, low-noise MMIC amplifiers usingpseudomorphic MODFETs

State-of-the-art, 60-GHz, low-noise MMICs based on pseudomorphic modulation-doped FETs, with 0.25-μm×60-μm gates offset 0.3 μm from the source ohmic, are discussed. Single-state low-noise amplifiers (LNAs) exhibited minimum noise figures of 2.90 dB with 4.1 dB of associated gain at 59.25 GHz. Dual-state MMICs had minimum noise figures of 3.5 dB and 10.8 dB of associated gain at 58.50 GHz. Cascaded four-stage LNAs (two dual-stage MMICs) had minimum noise figures of 3.7 dB and over 20.7 dB of associated gain at 58.0 GHz. Finally, when biased for maximum gain, the four-stage amplifier exhibited over 30.4 dB of gain at 60.0 GHz     

A narrow-channel, 0.2-μm gate-length, double-quantum-wellpseudomorphic MODFET with high power gain at millimeter-wave frequencies

State-of-the-art pseudomorphic MODFETs were developed with metallurgical gate lengths between 0.22 and 0.25 μm, very short source-to-drain spacings of 0.7 μm, and a double-quantum-well material structure. S-parameter measurements were performed on these 60-μm gate-width devices up to 40 GHz. From these S-parameter measurements, an extrapolated value of 82 GHz was estimated for F_t. Modeling of the power gain as a function of frequency indicates that F_max may be as high as 305 GHz     

Self-consistent modeling of heating and MOSFET performance in 3-D integrated circuits

We present a new method for finding the temperature profile of vertically stacked three-dimensional (3-D) digital integrated circuits (ICs). Using our model, we achieve spatial thermal resolution at the desired circuit level, which can be as small as a single MOSFET. To resolve heating of 3-D ICs, we solve nonisothermal device equations self-consistently with lumped heat flow equations for the entire 3-D IC. Our methodology accounts for operational variations due to technology nodes (hardware: device), chip floor plans (hardware: layout), operating speed (hardware: clock frequency), and running applications (software). To model hardware, we first decide on an appropriate device configuration. We then calculate elements of the lumped thermal network using the 3-D IC layout. To include software, chip floor plan, and duty cycle-related performance variations, we employ a statistical Monte Carlo type algorithm. In this paper, we investigate performance of vertically stacked 3-D ICs, with each layer modeled after a Pentium III. Our calculated results show that layers within the stacked 3-D ICs, especially the ones in the middle, may greatly suffer from thermal heating.     

60-GHz pseudomorphic-MODFET low-noise MMIC amplifiers

The development of V-band low-noise monolithic microwave integrated circuits (MMICs) based on pseudomorphic modulation-doped FETs (P-MODFETs) is presented. These dual-stage MMICs incorporate P-MODFETs, with 0.35-μm×60-μm gates, as the active elements, electron-beam-written tuning elements, and DC-blocking and bias networks. The dual-stage chips exhibited a maximum gain of 10.2 dB at 59.5 GHz and a minimum noise figure of 5.3 dB, with an associated gain of 8.2 dB at 58.2 GHz. A cascaded four-stage amplifier using two MMIC modules exhibited 5.8-dB minimum noise figure with an associated gain of 18.3 dB at 58 GHz and up to 21.1 dB of maximum gain     

Histology and immunohistochemistry of benign vaginal polyps and the normal vaginal subepithelial layer

A Gel exclusion chromatographic method was used to determine the molecular weight distribution, and therefore, the origin, of non-dialysable urinary glucoconjugates in normal men. The results showed a mixture of glucoconjugates with molecular weight ranges of 1605 to 141,000. It is suggested that the high molecular weight forms originally constitute the glucoconjugates, and that they are probably post-glomerular in origin. These may be degraded in vivo by glucosylhydrolases to produce the low molecular weight forms. The activities of the urinary enzymes may be reduced in male type 1 diabetic patients, and this may be responsible for the reported increase in their excretion of non-dialysable urinary glucoconjugates.     

Neurodevelopmental outcome after prenatal exposure to opiates

The new population on dialysis today consists mainly of high risk patients (the elderly, diabetics, etc.) with high cardiovascular scores, and such vascular pathology is the most important predisposing factor for the occurrence of a frequent intradialytic clinical complication, vascular instability syndrome, which covers a range of clinical problems. Recently a new dialysis technique, profiled hemodialysis (PHD), has been set up and proposed for routine use. PHD consists of the clinical use of preestablished individual dialysis profiles aimed at antagonizing the changes in intradialytic plasma osmolarity by continuous modulation of dialysate sodium concentration throughout the whole extracorporeal session. In particular, PHD aims at reducing the fall of plasma osmolarity in the first half of the session (when it is higher) by reducing the sodium removal rate through increasing its dialysate concentration while taking into account the desired individual sodium balance to be reached at the end of the session. In this work, we report clinical experience with PHD compared to standard hemodialysis with constant sodium dialysate (SHD) in terms of its efficacy to maintain a more stable intradialytic blood volume (BV) and more stable hemodynamics. The PHD used in this work has been implemented by a mathematical model for computing the individual dialysate sodium profile which we have recently validated (Ursino M, Coli L, La Manna G, Grilli Cicilioni M, Dalmastri V, Guidicissi A, Masotti P, Avanzolini G, Stefani S, Bonomini V. A simple mathematical model of intradialytic sodium kinetics: "in vivo" validation during hemodialysis with constant or variable sodium. Int J Artif Organs 1996;19:393-403.). Eleven uremic patients affected by hypotension at the beginning of dialysis treatment were studied. Each patient first underwent an SHD treatment and 1 week later a PHD treatment. The 2 extracorporeal sessions (one on SHD and the other on PHD) were performed in each individual patient under identical operative conditions including the sodium mass removal by the end of the session and the ultrafiltration rate. The crit line and Doppler echocardiography were used to determine BV, cardiac output (CO), and stroke volume (SV) throughout the sessions. The mean blood pressure (MBP) and heart rate (HR) were simultaneously monitored. PHD was associated with a more stable intradialytic BV and more stable hemodynamics compared to SHD. The higher stability of BV and cardiac function (in terms of SV and CO maintenance) which was obtained above all in the first half of the PHD session was associated with a higher stability of the MBP and the HR. This resulted in an enhancement in cardiovascular tolerance to ultrafiltration throughout the session in all tested patients. In contrast, SHD in the same patients was characterized by early significant changes in BV and cardiovascular parameters resulting in a significant decrease of the MBP and a significant increase of the HR throughout the session and also 1 h after the end of dialysis. Our results indicate that PHD may represent an efficient approach for the treatment of patients suffering from intradialytic vascular instability. If long-term clinical practice confirms the efficacy of PHD in controlling dialysis intolerance symptoms, it will have great scope as a routine procedure.     

Decreased activity of acid alpha-glucosidase in a patient with persistent periocular swelling after infusions of hydroxyethyl starch

After infusion therapy with hydroxyethyl starch (HES) on account of sudden hearing loss, a 68-year-old woman developed a marked and persistent periocular swelling. This extraordinary adverse effect caused us to search for an explanation by means of histopathology, immunohistochemistry, immunoelectron microscopy and biochemistry. In lesional periocular skin and in normal-appearing skin, lysosomal storage of HES could be detected with a specific HES antibody in histiocytes, endothelial cells, basal keratinocytes and small nerves. In the periocular skin, a stronger deposition of HES was found in addition to distinct xanthomatous changes as well as features of lymphoedema. In view of lysosomal HES storage we measured the pH-dependent activity of the lysosomal alpha-glucosidase (GAA) in cultured fibroblasts. We found a 50% decreased activity of the acid GAA, which is consistent with a heterozygous state of glycogenosis type II (Pompe's disease) and potentially of pathogenetic relevance for the intralysosomal accumulation of HES. Xanthomatous changes and lymphoedema are likely to be secondary effects, but contribute considerably to the clinical manifestation of persistent visible swelling. This observation could point to a role for GAA in the elimination of tissue-stored HES. Patients with decreased activities of GAA may be at risk of unusual adverse effects following extraordinary and prolonged tissue storage of HES, especially if it is infused in large quantities.     

Hypomelanosis guttata idiopathica]

A 37-year-old white female with dark complexion presented with progressive hypopigmented macules on the face and upper trunk. She was in good health and her family history was unremarkable. Histologic examination of the hypopigmented patches revealed reduced melanin within the basal layers of the epidermis. Using immunohistochemical and ultrastructural studies, the number of melanocytes appeared normal but signs of degeneration were evident and dendrites were shortened. The diagnosis of idiopathic guttate hypomelanosis was established. The clinical picture, etiology and treatment of this relatively common but often unrecognized skin disease is discussed.