A 1-Gb/s/pin 512-Mb DDRII SDRAM using a digital DLL and a slew-rate-controlled output buffer

A 1-Gb/s/pin 512-Mb DDRII SDRAM has been developed using a digital delay-locked loop (DLL) and a slew-rate-controlled output buffer. The digital DLL has a frequency divider for DLL input, performs at an operating frequency of up to 500 MHz at 1.6 V, and provides internal clocking with 50% duty-cycle correction. The DLL has a current-mirror-type interpolator, which enables a resolution as high as 14 ps, needs no standby current, and can operate at voltages as low as 0.8 V. The slew-rate impedance-controlled output buffer circuit reduces the output skew from 107 to 10 ps. This SDRAM was tested using a 0.13-/spl mu/m 126.5-mm/sup 2/ 512-Mb chip.     

The metabolic anatomy of tremor in Parkinson's disease

OBJECTIVE: To identify regional metabolic brain networks related specifically to the presence of tremor in PD. BACKGROUND: The pathophysiology of parkinsonian tremor is unknown. Because tremor in PD occurs mainly in repose, we used resting state PET with 18F-fluorodeoxyglucose (FDG) to identify specific metabolic brain networks associated with this clinical manifestation. METHODS: We studied two discrete groups of eight PD patients with and without tremor using FDG/PET. Both patient groups were matched for gender, age, and Unified Parkinson Disease Rating Scale ratings for akinesia and rigidity. Ten normal volunteer subjects served as controls. RESULTS: Network analysis with the Scaled Subprofile Model was performed in two steps. 1) We computed the expression of the PD-related pattern (PDRP) identified by us previously in each of the PD patients and control subjects. Although PDRP subject scores were abnormally elevated in the combined PD cohort (p < 0.005), these values did not differ in the PD patient groups with and without tremor (p = 0.36). 2) We used SSM to analyze the data from the combined PD cohort comprising both patient groups. We found that PD patients with tremor were characterized by increased expression of a metabolic network comprising the thalamus, pons, and premotor cortical regions. Subject scores for this pattern were elevated in the tremor group compared with the atremulous patient group and the normal control group (p < 0.005). CONCLUSIONS: The findings suggest that PD patients with tremor are characterized by distinct increases in the functional activity of thalamo-motor cortical projections. Modulation of this functional anatomic pathway is likely to be the mechanism for successful interventions for the relief of parkinsonian tremor.     

Patterns of expression for the mRNA corresponding to the four isoforms of phospholipase Cbeta in mouse brain

Ligand binding to neurotransmitter and hormone receptors which couple to the Gq subclass of GTP-binding protein leads to the activation of phospholipase Cbeta (PLCbeta) which hydrolyses phosphatidyl-inositol 4,5-bisphosphate, yielding a pair of second messengers, diacylglycerol and inositol 1,4,5-trisphosphate (IP3). The expression of PLCbeta1-4 mRNAs was comparatively examined by in situ hybridization in the mouse brain. In adults, PLCbeta1 mRNA was expressed predominantly in the telencephalon, including the cerebral cortex, hippocampus, amygdala, lateral septum and olfactory bulb, with little expression in most thalamic nuclei. PLCbeta2 mRNA was distributed in the white matter, suggesting its expression in non-neuronal cells, most likely oligodendrocytes. PLCbeta3 mRNA was specifically expressed in cerebellar Purkinje cells. The highest levels of PLCbeta4 mRNA were detected in Purkinje cells. High levels of PLCbeta4 mRNA were also found in the thalamus and medial septum, whereas weak signals were detected in most telencephalic regions, thus showing an expression pattern almost reciprocal to that of PLCbeta1 mRNA. During development, such characteristic regional expression of PLCbeta1 and PLCbeta4 were observed starting in late foetal stages, while specific expression of PLCbeta2 and PLCbeta3 appeared in early postnatal stages. We conclude that despite the existence of four PLCbeta isoforms, only one or two of them is expressed in individual neurons and glial cells. The distinct expression of PLCbetas provides a molecular basis for analysing the nature of the specific signal transduction pathway leading to the production of diacylglycerol and IP3 in distinct cell types and in different regions of the brain.     

Ectopic expression of DAN enhances the retinoic acid-induced neuronal differentiation in human neuroblastoma cell lines

Retinoic acid (RA) plays a major role in neuronal cell differentiation. Neuroblastoma cells differentiate in vitro by extending neurites and forming ganglion-like aggregates in response to RA. In the present study, we have examined a biological role(s) of DAN in the regulation of RA-mediated cellular differentiation in neuroblastoma cells. RTBM1 and SH-SY5Y cells undergo marked morphological changes associated with a remarkable induction of DAN gene expression when exposed to RA. By transfecting an expression vector harboring a rat DAN cDNA into SH-SY5Y cells, we have obtained two independent transfectants which express a large amount of DAN. The forced expression of DAN gene enhanced the neurite extension in the presence of RA, suggesting that DAN gene product might contain some regulatory role(s) in the RA-induced cellular differentiation in neuroblastoma cells.     

An instantaneous response CMOS optical receiver IC with widedynamic range and extremely high sensitivity using feed-forwardauto-bias adjustment

An instantaneous response CMOS optical-receiver IC is described with wide input dynamic range and high sensitivity. In a TCM (time compression multiplexing)-TDMA (time division multiple access) fiber-optic subscriber system, a receiver should be able to handle burst-data packets with different amplitude. This requires quick response and a wide dynamic range. Instantaneous response is achieved with a new feed-forward auto-bias adjustment technique. In addition, multistaged offset compensation provides a wide dynamic range without any external elements and adjustments. Using these design techniques, an optical receiver IC was fabricated in a standard 0.8-μm CMOS technology. The receiver has a wide dynamic range of more than 25 dB for burst-mode optical input at 29 Mb/s. It has high transimpedance gain of 150 dBΩ and high sensitivity of -42 dBm with stable operation for FET threshold voltage and power supply voltage fluctuation     

A mesenteric liposarcoma with production of granulocyte colony-stimulating factor

A 77-year-old female was admitted to our hospital because of pyrexia and a right retroperitoneal mass. Leukocytosis and other inflammatory findings were noted. Bone-marrow aspiration revealed hypercellularity with no malignant cells. An additional mass was detected sonographically in the pelvis. The serum concentration of granulocyte colony-stimulating factor (G-CSF) was highly elevated (299 pg/ml). The tumors were removed at laparotomy, and the pelvic mass was found to arise from the ileocecal mesentery. Postoperatively, white blood cell count and serum G-CSF concentrations decreased to normal levels. The mesenteric tumor showed weakly positive immunostaining for human G-CSF, and Northern and polymerase chain reaction (PCR) analyses detected CSF and its mRNA in the mesenteric tumor.     

A Taxonomy of Representation Strategies in Iconic Communication

Predicting whether the intended audience will be able to recognize the meaning of an icon or pictograph is not an easy task. Many icon recognition studies have been conducted in the past. However, their findings cannot be generalized to other icons that were not included in the study, which, we argue, is their main limitation. In this paper, we propose a comprehensive taxonomy of icons that is intended to enable the generalization of the findings of recognition studies. To accomplish this, we analyzed a sample of more than eight hundred icons according to three axes: lexical category, semantic category, and representation strategy. Three basic representation strategies were identified: visual similarity; semantic association; and arbitrary convention. These representation strategies are in agreement with the strategies identified in previous taxonomies. However, a greater number of subcategories of these strategies were identified. Our results also indicate that the lexical and semantic attributes of a concept influence the choice of representation strategy.