High-speed InGaP/GaAs HBTs with a strained InxGa1-xAs base

A self-aligned InGaP/GaAs heterojunction bipolar transistor with a compositionally graded In_xGa_1-xAs base has been demonstrated with f_T=83 GHz and f_max=197 GHz. To our knowledge, these results are the highest reported for both parameters in InGaP/GaAs HBT's. The graded base, which improves electron transport through the base, results in a DC current gain and a cutoff frequency which are 100% and 20% higher, respectively, than that achieved by an identical device with a nongraded base. The high f_max results from a heavily doped base, self-aligned base contacts, and a self-aligned collector etch. These results demonstrate the applicability of InGaP/GaAs HBT's in high-speed microwave applications     

Ahch, the mouse homologue of DAX1: cloning, characterization and synteny with GyK, the glycerol kinase locus

We cloned the murine full-length cDNA encoding Ahch, the mouse homologue of DAX1 (DSS-AHC Region on Human X Chromosome, Gene1) which is the gene responsible for human X-linked adrenal hypoplasia congenita (AHC) and hypogonadotropic hypogonadism (HH). Sequence analysis revealed that the murine and human cDNAs have 65% aa identity and 75% aa similarity overall. The cysteine residues in the putative DNA binding domain, which may interact with Zn2+ ions to form zinc fingers, are 100% conserved between the two species, indicating that the novel zinc-finger structures in DAX1 may be functional. In addition, mouse interspecific backcrosses show that the Ahch gene is closely linked to the glycerol kinase locus, GyK, on the mouse X chromosome, indicating that the order of the loci is conserved in this syntenic region between mouse and human.     

Spermatozoa-like cell invaders (nuclear vlimata) in human neoplasia

Spermatozoa-like cells (nuclear vlimata) have been identified in malignant cell cultures and embryonic cells, also common in the cytology and histology of all types of human neoplasia even after chemotherapy. A new mechanism of invasion of malignant cells has been described, according to which neoplastic cells behave and function as parasites using host-cells to divide, survive and eventually produce nuclear vlimata (bullets). Nuclear vlimata are the end cell products of incomplete, unequal, assymetrical division of neoplastic cells. The nuclear vlima exhibits similar morphology to spermatozoa and virus (head with, or without, tail) and invades the cytoplasm and/or nucleus of surrounding host-cells by a similar mechanism to sperm-oocyte interaction (fertilization) or viral cell infection, in the events of nuclear vlima-->tumor-->nuclear vlima-->tumor. The nuclear vlima head contains and transfers DNA, and when incorporated into the host-nucleus is indistinguishable from nucleoli and when in the cytoplasm is similar to sperm pronucleus, observed after sperm penetration of the oocyte. Function of nuclear vlimata is directly dependent on the specific extracellular matrix produced by malignant cells, consisting of glycosaminoglycans-protease-membranes. This mechanism of invasion constitutes the link of all scientific information concerning human neoplasia.     

Optimum spread spectrum signals for wideband channel sounding

Optimum periodic spread spectrum test signals suitable for wideband channel sounding are introduced. In contrast to conventional test signals based on m sequences, the proposed test signals with complex lowpass equivalents offer minimum crest factors in order to minimise the outband power spectral density at the output of a nonlinear transmitter amplifier.<>     

The relationship between coffee consumption and serum cholesterol under consideration of smoking history

To provide insight into the stream of Medicare payments over time, a sixteen-year longitudinal study examines three age cohorts of beneficiaries, looking separately at beneficiaries who died during the study period and those who survived. The common wisdom that a small minority of the population accounts for a large majority of health care expenditures is tempered when health care use is examined over an extended period of time. By putting high average costs in the final years of life in the context of a cohort's total lifetime experience, the study shows a leveling of spending over time, resulting in a lower concentration of health care resources on a small fraction of the population.     

Transient thermal performance of line traps

This paper develops a transient thermal model for line traps. The model was incorporated into a computer program that numerically integrates the governing nonlinear differential equation in time to predict critical temperatures and component short and long term ratings for a wide range of operating conditions. The model accounts for many factors including: variable air properties, variable material properties, environmental conditions, and a wide variety of component geometries and orientations. To verify the temperatures predicted by the thermal model, The Georgia Power Research Center carried out an extensive series of indoor laboratory tests to experimentally measure temperatures of energized line traps under transient loading conditions. Model predictions were within 8°C for 75 percent of the data. This paper presents the development of the governing equations and describes in detail the calculation of the convective and radiative components of heat transfer. Comparisons of the model predictions for two different line trap designs in different orientations to experimental data are presented to demonstrate the accuracy and flexibility of the thermal model