Information Seeking Can Be Social

For reasons ranging from obligation to curiosity, users have a strong inclination to seek information from others during the search process. Search systems using statistical analytics over traces left behind by others can help support the search experience.     

Deposition thickness based high-throughput nano-imprint template

International Technology Roadmap for Semiconductors 2003 projected nano-imprint lithography has the potential of high throughput, sub-20 nm resolution, and low cost [S.Y. Chou, P.R. Krauss, P.J. Renstrom, Appl. Phys. Lett. 67 (1995) 3144; Science 272 (1996) 85, J.A. Rogers, C. Mirkin, Mater. Res. Bull. 26 (2001)]. For nano-imprint lithography, a template with 1X resolution is required. The existing industrial infrastructure for supporting deep ultra violet 4X photo masks by e-beam and/or a laser beam scanning writer does not offer pitch (center-to-center distance of an array of patterned lines) less than ∼60 nm [<http://public.itrs.net/2003ITRS>]. For nano-imprint lithography to be accepted across the industry, a reproducible simple fabrication process to make a high resolution, single emboss template is essential [L. Jay Guo, J. Phys. D: Appl. Phys. 37 (2004) R123-R141]. Here we show, a general fabrication method and fabricated nano-imprint templates with sub-15 nm template line width and 10 nm pitch length through out the entire 200 mm wafer, varying the deposition thickness of multiple alternate films, using atomic layer deposition. Although multilayer nano-imprint templates and their exciting use have been demonstrated, [W.J. Dauksher et al., J. Vac. Sci. Technol. B 22 (2004) 3306, B. Heidari, et al., The 49th international conference on electron, ion and photon beam technology and nanofabrication, Orlando, Florida, 2005, William M. Tong, et al., Proc. SPIE 5751 (2005) 46-55, N.A. Melosh, A. Boukai, F. Diana, B. Gerardot, A. Badolato, P.M. Petroff, J.R. Heath, Science 300 (2003) 112] such a small pitch was not shown and either complex lattice mismatch-based epitaxially grown films or unconventional etch chemistry was used. The bare necessity was a simple and economical fabrication process for a high throughput nano-imprint template. In that context, we have developed a template fabrication process using classical micro-fabrication techniques. Successful use of these techniques made the template fabrication process simple, economical, and expedient. Also a novel technique to provide flexible and accurate alignment for nanowire patterning has been described. In this technique, nanowire patterning is accomplished on the entire wafer with a single impression. Industry level batch-fabrication of our scheme illustrates its reproducibility and manufacturability. We anticipate, this simple, economical and time saving technique will help researchers and developers to perform their experiment on nano-scale feature patterned substrates easily and conveniently.     

部署40G技术正当时

当今业内普遍达成的一个共识是运营商不应单纯为追求高速度的虚名而采用40G技术，应该等待40G技术具备与现有技术相当的性价比，也就是说，当40G技术的成本降至10G技术的四倍以下时才予以采用。然而，对于何时能够降至四倍以下，则众说纷纭。例如，有人指出当前40G技术的成本是10G技术的十倍。在本文中，我们将分析40G传输技术应用障碍如何被夸大或误解，同时指出目前已投入商用的40G产品的成本已不足10G技术的四倍。从理论上讲，40G线路信号所要求的光信噪比（OSNR）高出10G信号6分贝，这意味着10G信号可以不经再生传输更远的距离。…     

A Methodology for Architecture Exploration of Heterogeneous Signal Processing Systems

We present a methodology for the exploration of signal processing architectures at the system level. The methodology, named SPADE, provides a means to quickly build models of architectures at an abstract level, to easily map applications, modeled as Kahn Process Networks, onto these architecture models, and to analyze the performance of the resulting system by simulation. The methodology distinguishes between applications and architectures, and uses a trace-driven simulation technique for co-simulation of application models and architecture models. As a consequence, architecture models need not be functionally complete to be used for performance analysis while data dependent behavior is still handled correctly. We have used the methodology for the exploration of architectures and mappings of an MPEG-2 video decoder application.     

Isomers of dechlorane plus in Lake Winnipeg and Lake Ontario food webs

The extent of bioaccumulation of the syn- and anti-isomers of Dechlorane Plus (DP) is assessed in archived food web samples from Lake Winnipeg and Lake Ontario. Concentrations of the isomers were determined using purified analytical solutions of individual isomers as opposed to the technical mixture. The syn-isomer was consistently detected in all samples from both lakes; the anti-isomer was detected in all Lake Ontario samples, but only 45% of the samples from Lake Winnipeg. The pattern of bioaccumulation was different for the isomers in Lake Winnipeg. The anti-isomer was dominant in higher trophic level (TL) organisms like walleye [arithmetic mean +/- 1 x standard error: 730 +/- 120 pg/g, lipid weight (1w)] and goldeye (760 +/- 170 pg/g, Iw) while the syn-isomer dominated the lower TL organisms like zooplankton (550 +/- 40 pg/g, Iw) and mussels (430 +/- 140 pg/g, Iw). In Lake Ontario, the extent of bioaccumulation of the isomers and concentrations was greatest in the lower TL benthic organism, Diporeia (syn, 1307 +/- 554; and anti, 3108 +/- 898 pg/g Iw) and also high in zooplankton (syn, 719; and anti, 1332 pg/g Iw). This suggests that the isomers are bioavailable in sediment and that, despite their molecular size, diffusion from the water column into zooplankton can occur. Differences in the mean fractional abundance of the anti-isomer (mean fanti = mean concentration of the anti-isomer divided by sum of mean syn- and anti-concentrations) were pronounced in sediments between lakes (Lake Winnipeg mean fanti = 0.610, Lake Ontario mean fanti = 0.860) and the extent of enrichment (anti-) and depletion (syn-) of the isomers were more marked in Lake Winnipeg biota. There were also differences in the biomagnification potentials, as measured bythe trophic magnification factor (TMF), between the isomers in the Lake Winnipeg food web; no statistically significant TMFs for either isomer were found for the     

Natural-light labeling of tomatoes does not facilitate growth or penetration of Salmonella into the fruit

The survival-growth capacity of Salmonella populations on tomato epidermis labeled by a natural-light labeling system was investigated after persistent fears of such marks serving as possible entryways for the pathogenic organisms, alone and in the presence of Pectobacterium carotovorum subsp. carotovorum, a soft-rot organism. Different treatments involving natural-light labeling, fruit waxing, and a five-strain cocktail of Salmonella were applied to mature green tomato surfaces in different sequences prior to storage at 4, 12, or 25°C. Fruit was sampled every 3 days, and Salmonella was enumerated from all treatments and unlabeled fruit, which served as controls. There were no significant differences between treatments or between treatments and controls throughout. The results indicate that the cuticle and epidermal interruptions caused by natural-light labeling do not facilitate the penetration and colonization of the tomato pericarp. In a separate set of experiments, the capacity of Salmonella to penetrate tomato in the presence of a potential synergism with P. carotovorum subsp. carotovorum was investigated. The addition of P. carotovorum at higher, lower, or equal population densities to Salmonella did not significantly alter the behavior of Salmonella on tomatoes stored at 25°C, regardless of natural-light labeling. The inability of P. carotovorum and Salmonella to colonize natural-light-etched surfaces of tomato fruit indicates that the use of this technology does not adversely compromise the surface of tomatoes.     

Concentration and bioaccumulation of dechlorane compounds in coastal environment of northern China

Dechloranes, including Dechlorane Plus (DP), Mirex (Dechlorane), Dechlorane 602 (Dec 602), Dechlorane 603 (Dec 603), and Dechlorane 604 (Dec 604), were determined using GC-MSD for water, sediment and oyster samples collected at 15 sampling sites near the Bohai and Huanghai Sea shore area of northern China in 2008. DP and Mirex were detected in most water, sediment, and oyster samples, which indicated widespread distribution of these two compounds. The mean concentrations in water, sediment and oyster samples, respectively, were 1.8 ng/L, 2.9 ng/g dry weight (dw) and 4.1 ng/g wet weight (ww) for total DP, and 0.29 ng/L, 0.90 ng/g dw, and 2.0 ng/g ww for Mirex. Dec 602 and Dec 603 were not detected in water but in small portions of the sediment and oyster samples, showing a low level of contamination by these two chemicals in the region. Strong and significant correlations were found between total DP and Mirex concentrations in water, sediment and oyster samples, probably suggesting similar local sources of these two chemicals. Dec 604 was not found in any samples. The biota-sediment accumulation factor (BSAF) of DP, Mirex, and Dec 602 declined along with the increase of their logarithm of octanol-water partition coefficients (log Kow), possibly indicating that compounds with lower log Kow (like Mirex and Dec 602) accumulated more readily in biota. The mean fractional abundance of syn-DP (fsyn) was 0.34 in water samples, a value lower than that in Chinese commercial mixture (0.41), while the mean fsyn for surface sediment (0.44) and oyster (0.45) samples were higher than technical values. Enrichment of syn-DP in oyster was in agreement with previously reported findings in Great Lakes fish. Enrichment of syn-DP in marine surface sediments, however, is contrary to data reported for fresh water sediments. To our knowledge this is the first report of Dec 602, Dec 603, and Dec 604 in a marine environment and also the first report of Dechloranes in marine biota.     

Kairomones and their use for management of entomophagous insects

In laboratory experiments conducted to compare the kairomonal activity forMicroplitis croceipes (Cresson) of frass fromHeliothis zea (Boddie) larvae fed on different host plants,M. croceipes females responded to extracts of frass from larvae reared on cotton or soybeans but not on corn. The lack of response to frass from larvae reared on corn was shown to be a result of a lack of some appropriate chemical(s) in the corn.Lepidoptera: Noctuidae.Hymenoptera: Braconidae.In cooperation with the University of Georgia College of Agriculture Experiment Stations, Coastal Plain Station, Tifton, Georgia 31793. Accepted for publication February 9, 1981.Mention of a proprietary product in this paper does not constitute an endorsement by this product by the USDA.     

Sensitivity analysis based preform die shape design for net-shape forging

A sensitivity analysis method for preform die shape design in net-shape forging processes is developed in this paper using the rigid viscoplastic finite element method. The preform die shapes are represented by cubic B-spline curves. The control points or coefficients of B-spline are used as the design variables. The optimization problem is to minimize the zone where the realized and desired final forging shapes do not coincide. The sensitivities of the objective function, nodal coordinates and nodal velocities with respect to the design variables are developed in detail. A procedure for computing the sensitivities of history-dependent functions is presented. The remeshing procedure and the interpolation/transfer of the history-dependent parameters, such as effective strain, are stated. The procedures of sensitivity analysis based preform die design are also described. In addition, a method for the adjustment of the volume loss resulting from the finite element analysis is given in order to make the workpiece volume consistent in each optimization iteration. The method developed in this paper is used to design the preform die shape of H-shaped forging processes, including plane strain and axisymmetric deformations. The results show that a flashless forging with a complete die fill is realized using the optimized preform die shape.