40 Gbit/s limiting output buffer in 80 nm CMOS

A 40 Gbit/s 1V limiting output buffer for an AC-coupled 50 /spl Omega/ load with a differential output swing of 660 mV and a gain of 18 dB is presented. A power consumption of only 24 mW and a simulated risetime of 11 ps are achieved by means of a systematic buffer optimisation.     

Magnetic Field Response in (UTh)Be13

We report on recent magnetic field studies on U _1–xTh_xBe ₁₃ with x0.1. These new results are related to previous data published by Kromer et al. [F. Kromer et al., Phys. Rev. B 62, 12477 (2000)]. The new magnetization measurements confirm the existence of an anomaly found earlier through calorimetric and dilatometric measurements at T _L c for x c1 0.019. In the critical concentration range x _c1 c2 0.0455, the critical-field curves for the mean field type of phase transition that occur at T _c1 and T _c2 (at zero field) appear to merge as T0. This interesting fact which has been inferred already from the previous measurements could be confirmed for a sample with x=0.038. The normal state for Th concentrations xx_c2 is rather unusual: A negative normal-state contribution, _n, is observed in the thermal expansion coefficient as well as the occurrence of a positive peak when superconductivity is suppressed by a magnetic field. Both effects are studied in detail and a comparison to specific heat results is given. Finally, we have investigated the non-linear contribution to the magnetization, ⁽³⁾ , of UBe ₁₃ and U _0.9 Th _0.1 Be ₁₃ . In contradiction to suggestions made previously by Aliev et al. [Aliev et al., Europhys. Lett. 32, 765 (1995)] for x=0.1, ⁽³⁾ remains negative down to T100 mK, the lowest temperature investigated.     

Sample size required to estimate a parameter in the power function distribution

The purpose of this paper is to establish a two step sampling procedure for estimating the parameter θ of the power function distribution to within givend units of its true value with a given probability 1—α;(0<α<1). The density of the power function distribution is a function of two parameters, the second of whichk is assumed known. Given a preliminary sample sizem, tables and formulas are presented by which one may establish the sizen of the second sample such thatP(|y _n —θ|<d)>1—α is true, wherey _n is the largest observation in the second sample. The method used is deriving the results of this paper is similar to that given by Graybill and Connell (1964) and since the power function density reduces to the uniform density whenk=0, their results can be derived from the formulas given here. Also a table of comparisons between the expected second sample size in this paper and two other solutions is given.

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Sumario El propósito de este escrito es el de establecer un procedimiento de muestreo de dos pasos, para estimar el parámetro de la distribución de funciones de potencia cerca ded unidades de su valor verdadero con una probabilidad 1—α;(0<0<α<1). la densidad de la distribución de funciones de potencia es una función de dos parámetros, el segundo de los cualesk se supone es conocido. Dado un tama?o de muestra preliminarm, se presentan tabulaciones y fórmulas con las cuales se puede establecer el tama?on de la segunda muestra, de tal manera queP(|y _n —θ|<d)>1—α sea cierto, dondey _n es la observación más grande en la segunda muestra. El método usado en la derivación de los resultados de este escrito es similar al dado por Graybill y Connell (1964, Journal of the American Statistical Association) y ya que la densidad de funciones de potencia se reduce a la densidad uniforme cuandok=0, sus resultados pueden ser derivados a partir de las fórmulas dadas aquí. Además, se presenta una tabulación de comparaciones entre el segundo tama?o de muestra dado en este escrito y otras dos soluciones. Lafdp de la distribución de funciones de potencia es de la formaf(u)=(k+1)θ ^−(k+1) u ^k ,0<u<θ, θ>0 y cero en cualquiera otra parte.

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Research supported under ONR contract N00014-68-A-0515.     

Children's spatial knowledge of their school campus.

72 4th-, 6th-, and 8th-grade boys were tested with different methodologies for deriving measures of their knowledge of interlandmark distances and directions on their school campus. Results show that age group differences were not large and appeared comparable for most measures. However, other results indicated that measures derived from direction vs distance information were independent. First, the accuracy with which Ss made distance and direction estimates varied across specific combinations of reference sites and targets; this pattern of differential accuracy was quite different for distance vs direction estimates. Second, correlations among the dependent measures indicated that Ss who were accurate at direction estimates were not necessarily accurate for distance estimates. It is emphasized that measures derived from Ss' estimates of direction information were not comparable with measures derived from their estimates of distance information. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluation of a platinum leasing program for fuel cell vehicles

This paper evaluates the feasibility of a platinum leasing program for future fuel-cell vehicles (FCVs) in the United States. By internalizing the residual value of platinum in the vehicle's upfront cost, a platinum lease may offer cost savings to the consumer. Several leasing scenarios were evaluated to estimate potential cash savings.     

Characteristics of multicellular spheroids formed by primary cultures of human thyroid tumor cells

Features of multicellular tumor spheroids (MCTS) differed depending on their types of cells. MCTS formed by 4000 human thyroid primary culture epithelial tumor cells displayed diameters between 0.31 and 0.33 mm within 2 days regardless of the stage of malignancy of the originating tumors. Their cellular composition reflected that of the originating tumor in regard to DNA content and the expression of cytokeratin, vimentin, as well as thyroglobulin. During the following 3 weeks, their sizes increased up to diameters of 0.42 mm when their cells had been derived from carcinomas, and MCTS originating from adenomas stopped growing within the next 2 days. After 8 days of incubation, proliferating cells were only found in carcinoma MCTS. The cells were randomly distributed over the total volume of the spheroids, which displayed irregular cell arrangements but not concentric cell layers and did not form necrotic centers.     

From volatility to value: analysing and managing financial and performance risk in energy savings projects

Many energy-related investments are made without a clear financial understanding of their values, risks, and volatilities. In the face of this uncertainty, the investor—such as a building owner or an energy service company—will often choose to implement only the most certain and thus limited energy-efficiency measures. Conversely, commodities traders and other sophisticated investors accustomed to evaluating investments on a value, risk, and volatility basis often overlook energy-efficiency investments because risk and volatility information are not provided. Fortunately, energy-efficiency investments easily lend themselves to such analysis using tools similar to those applied to supply side risk management. Accurate and robust analysis demands a high level of understanding of the physical aspects of energy-efficiency, which enables the translation of physical performance data into the language of investment. With a risk management analysis framework in place, the two groups—energy-efficiency experts and investment decision-makers—can exchange the information they need to expand investment in demand-side energy projects. In this article, we first present the case for financial risk analysis in energy efficiency in the buildings sector. We then describe techniques and examples of how to identify, quantify, and manage risk. Finally, we describe emerging market-based opportunities in risk management for energy efficiency.     

Comparison of simulation and measurement of dynamic fiber-coupling effects for high-speed multimode VCSELs

Static and dynamic measurements are performed with GaAs oxide-confined vertical-cavity surface-emitting lasers (VCSELs), using multimode fibers with a core diameter of 50 and 62.5 /spl mu/m and different numerical apertures (NAs). They show that a small NA can have a severe impact on the eye opening and thus also on the bit-error rate. The measurements are analyzed with a spatiotemporal two-dimensional (2-D) multimode VCSEL model. The required parameter extraction for the model is verified with small- and large-signal measurements. The analysis shows that the change of the eye opening can be explained by the interaction between the mode- and the current-injection profile, carrier diffusion, and intermodal gain compression (IGC). IGC increases differences in the modal power distribution caused by the interaction between the mode profiles and the current-injection profile. Carrier diffusion is able to compensate these increased differences of the modal power distribution. Its impact, however, on dynamic changes caused by IGC is moderate.     

Truncated trkB receptors on nonneuronal cells inhibit BDNF-induced neurite outgrowth in vitro

The function of truncated trkB receptors during nervous system plasticity and regeneration is currently unknown. The extensive nonneuronal localization of truncated trkB-T1 receptors, coupled with their up-regulation by CNS glial cells in response to injury, has led to the speculation that these receptors may sequester BDNF and NT-4/5 to reduce their local availability and, thus, limit axonal sprouting. Conversely, trkB-T1 receptors could bind and present neurotrophins to injured axons and facilitate their regeneration in a manor analogous to that proposed for p75(NTR) receptors on Schwann cells. To address this issue, we used an in vitro coculture paradigm in which wild-type 3T3 NIH fibroblasts or two different 3T3 cell clones stably expressing trkB-T1 receptors served as monolayer substrates upon which to evaluate the effect of trkB-T1 receptors on nonneuronal cells to influence neurotrophin (NGF, BDNF, NT-3, and NT-4/5)-induced neurite outgrowth from retinoic acid (RA)-treated SY5Y neuroblastoma cells. In these experiments, BDNF and NT-4/5 produce a strong phosphorylation of trk receptors on the RA-SY5Y cells and induce differentiation of the SY5Y cells (as measured by the development of neurofilament-positive neuritic processes). This ability of the trkB ligands to stimulate neurite outgrowth is dose dependent since increasing concentrations of BDNF (5, 25, and 100 ng/ml) result in an increased percentage of SY5Y cells developing neurites and in progressively longer neurites from SY5Y cells on the control 3T3 monolayers. In these experiments, BDNF and NT-4/5 induce the strongest neurite outgrowth, followed by NT-3 and then NGF. When trkB-T1 receptors are present on the 3T3 cell substratum both BDNF- and NT-4/5-induced neurite extension from the SY5Y cells are strongly inhibited. In contrast, NGF-induced neurite growth is unaffected and NT-3-associated growth is somewhat reduced. These results suggest that the inhibitory effect of the trkB-T1 receptors on the nonneuronal cell substrates is selective for neurite outgrowth that is mediated via the trkB-kinase receptors on the neuroblastoma cells. This ability of trkB-T1 receptors on the nonneuronal substratum to inhibit BDNF-induced neurite outgrowth can be overcome by the addition of high concentrations of BDNF (1 microg/ml). Binding assays using 125I-BDNF suggest that this inhibitory effect could be mediated via binding and internalization of BDNF by the trkB-T1 receptors on the 3T3 cells. These results provide strong support for the hypothesis that the up-regulation of trkB-T1 receptors on astrocytes following CNS lesions enhances the sequestration of the trkB ligands, BDNF and NT- 4/5, at the site of reactive gliosis and, thus, contributes to the inhibition of CNS axonal regeneration from neurons expressing trkB-kinase receptors by removing their ligands from the extracellular environment.