Effects of Geometrical Discontinuities on Distributed Passive Intermodulation in Printed Lines

This paper presents the results of experimental study of passive intermodulation (PIM) generation in microstrip lines with U-shaped and meandered strips, impedance tapers, and strips with the profiled edges. It is shown that the geometrical discontinuities in printed circuits may have a noticeable impact on distributed PIM generation even when their effect is indiscernible in the linear regime measurements. A consistent interpretation of the observed phenomena has been proposed on the basis of the phase synchronism in the four-wave mixing process. The results of this study reveal new features of PIM production important for the design and characterization of low-PIM microstrip circuits.      

Growth hormone secretion and circulating insulin-like growth factor-I (IGF-I) and IGF binding protein-3 concentrations in children with sickle cell disease

Impaired growth involving both height and weight accompanying sickle cell disease (SCD) poses diagnostic and therapeutic problems. We undertook this study to test the hypothesis that this impaired growth is associated with abnormalities of the growth hormone (GH)/insulin-like growth factor-I (IGF-I)/IGF binding protein-3 (IGFBP-3) axis in 21 children with SCD and that SCD is associated with GH resistance. Nine of 21 children with SCD had a defective GH response to both clonidine and glucagon provocation (peak < 10 micrograms/L); these children differed from the 12 others in having slower linear growth velocity (GV and GVSDS), lower circulating concentrations of IGF-I and IGFBP-3, and either partial or complete empty sellae in computed tomographic scans of the hypothalamic-pituitary area. In this group of patients with SCD, it appears that defective GH secretion and consequent low IGF-I production are the major etiological factors causing the slow growth. The two groups with SCD did not differ significantly in dietary intake, body mass index (BMI), midarm circumferences, skinfold thickness, serum albumin concentration, or intestinal absorption of D-xylose. A single injection of GH produced a smaller increase in circulating IGF-I in children with SCD with or without defective GH secretion versus 10 age-matched children with idiopathic short stature (ISS) and 11 children with isolated GH deficiency (GHD), suggesting partial GH resistance in the SCD group. The presence of defective GH secretion, decreased IGF-I synthesis, and partial resistance to GH in short children with SCD suggests that treatment with IGF-I may be superior to GH therapy for improving growth.     

Fully depleted CMOS/SOI device design guidelines for low-powerapplications

We report the fully depleted (FD) CMOS/SOI device design guidelines for low-power applications. Optimal technology, device and circuit parameters are derived and compared with bulk CMOS based design. The differences and similarities are summarized. Device design guidelines using devices with L=0.1 μm for FDSOI low-power applications are presented using an empirical drain saturation current model fitted to experimental data. The model is verified in the deep-submicron regime by two-dimensional (2-D) simulation. For L=0.1 μm FDSOI low-power technology, optimum speed and lower-power occurs at V_dd=3V_th and V_dd=1.5 V_th, respectively. Optimum buried oxide thickness is found to be between 300 and 400 nm for low-power applications. Optimum transistor sizing is when the driver device capacitance is 0.3 times the total load capacitance. Similarly optimum gate oxide thickness is when the driver device gate capacitance is 0.2-0.6 times the total load capacitance for performance and 0.1-0.2 for low-power, respectively. Finally optimum stage ratio for driving large loads is around 2-4 for both high-performance and low-power     

A physically based compact device model for fully depleted andnearly fully depleted SOI MOSFET

A compact submicrometer Fully Depleted Silicon-On-Insulator (FDSOI) and Nearly FDSOI MOSFET device model suitable for analog as well as digital application has been proposed. It is an all region model. In developing this model care has been taken in retaining the basic functional form of physical models while improving the model accuracy and computational efficiency. In addition to the commonly included effects in the FDSOI MOSFET model, we have given careful consideration to parasitic source/drain resistance, Drain Induced Conductivity Enhancement (DICE) effect, floating body effect, self-heating and model continuity. A single parameter set is used for a large set of device dimensions except threshold voltage and parasitic source/drain resistance due to silicon film thickness variations. The accuracy of the model is validated with experimental data using NMOS FDSOI devices and found to be in good agreement     

Arachnoid cysts on computed tomography

The appearances of arachnoid cysts on computed tomography are presented. They are well defined lesions with the same density as cerebrospimal fluid and are not contrast enhanced. Superficial lesions are biconvex or semicircular and may have a characteristic straight inner margin. Deep lesions and cysts between the cerebellar hemispheres are spherical and some may be difficult to differentiate from cystic neoplasms. The etiology and clinical manifestations of arachnoid cysts are also briefly discussed.     

On buried oxide effects in SOI lateral bipolar transistors

We report buried oxide effects on the Silicon-On-Insulator Lateral Bipolar Transistor (SOILBT) performance by two-dimensional (2-D) numerical simulation and experiments. An early punchthrough is observed in SOILBT compared to the bulk due to the presence of buried oxide. In addition to dopant segregation into the buried oxide, the presence of buried oxide also diverts some electric field lines emanating from collector toward substrate, due to 2-D distribution of field, leaving fewer across the base region and hence increased depletion widths and punchthrough. One-dimensional (1-D) depletion approximation fails to predict this punchthrough. To establish the evidence of buried oxide induced punchthrough without dopant segregation effect, simple and yet novel measurement techniques are proposed to extract effective base width and base doping concentration near the buried oxide-silicon film interface using the parasitic MOSFET in SOILBT. Good agreement between 2-D simulation and experimental results was observed. Finally design curves are generated using 2-D numerical simulation for different base doping and buried oxide thicknesses on SOI substrates     

A new species of Vexillata (Nemata: Ornithostrongylidae) from the coarse-haired pocket mouse Chaetodipus hispidus in New Mexico

Individuals of a new species of trichostrongyloid nematode of the genus Vexillata were collected from the intestines of the coarse-haired pocket mouse Chaetodipus hispidus from eastern New Mexico. This new species possesses general features of the genus Vexillata but may be recognized as distinct from all other species by unique features of the dorsal ray of the caudal bursa and the synlophe.