经济宽带通信用的理想光纤

宽带指的是大容量、高速率(一般双向的速率超过256 kb it/s),因特网或网络的连接是通过比普通铜电话线的带宽高得多的同轴电缆或光缆实现的。宽带信道可以同时传输语音、图像和数据。现在有许多不同的技术适用于宽带通信,如铜线可用于数字用户线(DSL)技术,光纤技术可用于光纤到户(FTTH),有线电视网络和无线技术可用于W iF i和W i-M ax。光纤技术可以为采用FTTH网络(即光纤到最后一英里)的用户提供宽带业务。在城域网和接入网中使用理想光纤(ITUTG.652D)的特点是,理想光纤可以提供宽带业务。究其原因是低水峰ITUTG.652D在1 383±3 nm具有低衰减和小偏振模色散(PMD),从而满足和超过宽带网络对理想光纤的性能要求。     

Measurement of changes in viscosity in polymers with gamma-ray dose using a differential viscometer

Although some works on changes in viscosity of liquids with gamma-ray dose have been made near the “gel point”, very little works have been done below this point. Changes in viscosities of different-grade silicone fluids below gel point have been measured using a differential viscometer developed in our laboratory, capable of measuring change in viscosities of two liquids directly. Preliminary results on viscosity changes when irradiated with energetic alpha particles will also be reported.     

Series impedance of GaAs planar Schottky diodes operated to 500 GHz

The author discusses the impact of ohmic contacts on the series impedance of a GaAs cylindrical planar Schottky diode. The expression for the high-frequency impedance of an annular ohmic contact is developed using a novel transmission line model. This formulation is used to ascertain the contribution of the ohmic contact impedance to the overall device series impedance at both DC and 500 GHz. Diode impedance characterization indicates that the ohmic contact impedance makes a small contribution to the series impedance in comparison to that of the other components, both at DC and submillimeter wavelengths. Hence, the dimensions of the contact pads can be scaled down significantly without any appreciable increase in series impedance but with a decrease in the parasitic pad-to-pad capacitance. Finally, this modeling establishes theoretical guidelines regarding the allowable limits for specific contact resistance in small geometry diodes, so that the device I -V characteristics are not significantly altered as a result of the ohmic contact impedance     

Skewed multivariate models related to hidden truncation and/or selective reporting

The univariate skew-normal distribution was introduced by Azzalini in 1985 as a natural extension of the classical normal density to accommodate asymmetry. He extensively studied the properties of this distribution and in conjunction with coauthors, extended this class to include the multivariate analog of the skew-normal. Arnold et al. (1993) introduced a more general skew-normal distribution as the marginal distribution of a truncated bivariate normal distribution in whichX was retained only ifY satisfied certain constraints. Using this approach more general univariate and multivariate skewed distributions have been developed. A survey of such models is provided together with discussion of related inference questions.     

Xenon molecular laser in the vacuum ultraviolet

Vacuum ultraviolet emission from high-pressure Xe gas under excitation by a pulsed electron beam has been investigated. When cavity mirrors were provided, significant line narrowing and a thousandfold increase in spectral intensity occurred at 1730 ± 10 Å. This was accompanied by severe mirror burning and provides strong evidence that an associative molecular Xe laser has been achieved.     

Query processing over incomplete autonomous databases: query rewriting using learned data dependencies

Incompleteness due to missing attribute values (aka “null values”) is very common in autonomous web databases, on which user accesses are usually supported through mediators. Traditional query processing techniques that focus on the strict soundness of answer tuples often ignore tuples with critical missing attributes, even if they wind up being relevant to a user query. Ideally we would like the mediator to retrieve such possibleanswers and gauge their relevance by accessing their likelihood of being pertinent answers to the query. The autonomous nature of web databases poses several challenges in realizing this objective. Such challenges include the restricted access privileges imposed on the data, the limited support for query patterns, and the bounded pool of database and network resources in the web environment. We introduce a novel query rewriting and optimization framework QPIAD that tackles these challenges. Our technique involves reformulating the user query based on mined correlations among the database attributes. The reformulated queries are aimed at retrieving the relevant possibleanswers in addition to the certain answers. QPIAD is able to gauge the relevance of such queries allowing tradeoffs in reducing the costs of database query processing and answer transmission. To support this framework, we develop methods for mining attribute correlations (in terms of Approximate Functional Dependencies), value distributions (in the form of Naïve Bayes Classifiers), and selectivity estimates. We present empirical studies to demonstrate that our approach is able to effectively retrieve relevant possibleanswers with high precision, high recall, and manageable cost.     

Fragment docking to S100 proteins reveals a wide diversity of weak interaction sites

The S100 protein family is a highly conserved group of Ca(2+)-binding proteins that belong to the EF-hand type and are considered potential drug targets. In the present study we focused our attention on two members of the family: S100A13 and S100B; the former is involved in the nonclassical protein release of two proangiogenic polypeptides FGF-1 and IL-1alpha that are involved in inflammatory processes, whereas S100B is known to interact with the C-terminal domain of the intracellular tumor suppressor p53 and promote cancer development. We screened, using waterLOGSY NMR experiments, 430 molecules of a generic fragment library and we identified different hits for each protein. The subset of fragments interacting with S100B has very few members in common with the subset interacting with S100A13. From the (15)N-HSQC NMR spectra of the proteins in the presence of those hits the chemical shift differences Deltadelta(HN) were calculated, and the main regions of surface interaction were identified. A relatively large variety of interaction regions for various ligands were identified for the two proteins, including known or suggested protein-protein interaction sites.     

Double-Plume Integral Models for Near-Field Mixing in Multiphase Plumes

We present a generalized integral model for multiphase plumes in stratified ambient conditions based on the double-plume approach, where the plume is composed of a rising, multiphase core plume surrounded by a counterflowing outer ring plume of dense fluid. The generalized model captures as limiting cases the current approaches in the literature, including two-fluid and mixed-fluid equations, continuous and discrete detrainment, dispersed-phase mass transfer, and two models for entrainment in the counterflow region. These modeling approaches are compared and validated against both laboratory and field-scale data. In unstratified conditions, all model formulations perform equally well. In stratification, entrainment in the counterflow region is best represented by correlation to the inner plume velocity instead of the difference between the inner and outer plume velocities. The vertical distribution of the exchange between the inner and outer plumes in the models differs from that measured in the prototype due to enhanced entrainment at the detrainment zone and forced entrainment from the collapsing intrusion layer. Nonetheless, the models predict well the length scales and volume fluxes at the detrainment zone and intrusion layer. Applications are demonstrated for reservoir air bubble plumes. The mass transfer and near-field mixing in the double-plume integral model prove sufficiently accurate to predict the depth of maximum plume rise (both the locations of total dissolution of the bubbles and the maximum height of the decelerating plume) and the volume flux, dissolved constituent mass flux, and trap height of the intrusion.     

Dissolution of Direct Ocean Carbon Sequestration Plumes Using an Integral Model Approach

We present the results of a double-plume integral model for a positively buoyant multiphase plume of liquid carbon dioxide injected at mid-depths (500–2000?m) in the ocean. In addition to the relevant plume physics, the model accounts for dissolution of the carbon dioxide droplets, the effect on dissolution of clathrate hydrate films, and the increase in seawater density due to enrichment by dissolved carbon dioxide. Due to the creation of negative buoyancy in the entrained fluid through dissolution of carbon dioxide, the near-field mixing exhibits a complex set of energetic descending outer plume structures that do not converge to a steady state. The unsteady near field is shown to be inherent in the plume physics, resulting in enhanced distribution of the dissolved carbon dioxide over the plume height and formation of multiple, unsteady intrusion layers. Despite the complex plume near field, we demonstrate that the height of maximum plume rise has a steady solution. A general empirical design equation for the maximum height of plume rise is presented from the model results, dependent on the initial droplet diameter and buoyancy flux, the strength of the ambient stratification, and the linear mass transfer reduction factor due to hydrate formation. A sensitivity analysis of the design equation highlights the droplet diameter as the most important design variable and demonstrates that current uncertainty in the value of the mass transfer reduction factor results in uncertainty of the plume rise height within a factor of three.