High-velocity transport of nanoparticles through 1-D nanochannels at very large particle to channel diameter ratios

We explore the possibility of generating high-velocity flows of nanoparticles through flat-rectangular nanochannels, which are only 50% deeper than the diameter of the particles. Using the shear-driven flow principle, 200-nm particles can, for example, be transported through a 300-nm-deep channel at velocities up to 35 mm/s (upper limit of our current setup). Working under high-pH conditions, the velocity of the carboxylated nanoparticles still respects the small-molecule velocity law, despite the high degree of confinement to which the particles are subjected. The high degree of confinement is also found to lead to a reduced band broadening. When injecting sharply delimited particle plugs, the plate heights observed for the flow of 0.2-microm particles through a 0.3-microm channel (with plate heights of the order of 1-2 microm) are, for example, approximately 1 order of magnitude smaller than for the flow of 1.0-microm particles through a 1.4-microm channel. It is also found that the band broadening is, within its statistical variation, independent of the fluid velocity over a large range of particle velocities (5-35 mm/s). The flow method distinguishes itself from pressure-driven field-flow fractionation and hydrodynamic chromatography in that the mean particle velocity is independent of the particle size over the entire range of possible particle to channel diameter ratios.     

Controlled Nucleation of GaN Nanowires Grown with Molecular Beam Epitaxy

The location of GaN nanowires is controlled with essentially perfect selectivity using patterned SiN_x prior to molecular beam epitaxy growth. Nanowire growth is uniform within mask openings and absent on the mask surface for over 95% of the usable area of a 76 mm diameter substrate. The diameters of the resulting nanowires are controlled by the size of the mask openings. Openings of approximately 500 nm or less produce single nanowires with symmetrically faceted tips.     

MySpace is your space? Examining self-presentation of MySpace users

The study examined the role of self-presentation on MySpace pages through the information users post on their sites. MySpace users were more comfortable with posting the broad pieces of information, like gender, race, zodiac sign, and hometown. They were not as willing to present personal information like income, whether they smoke or drank or groups they belonged to. Age and motivations for creating a page were major predictors of how much information people revealed about themselves.     

Hierarchical image segmentation based on similarity of NDVI time series

Although a variety of hierarchical image segmentation procedures for remote sensing imagery have been published, none of them specifically integrates remote sensing time series in spatial or hierarchical segmentation concepts. However, this integration is important for the analysis of ecosystems which are hierarchical in nature, with different ecological processes occurring at different spatial and temporal scales. Therefore, the objective of this paper is to introduce a multi-temporal hierarchical image segmentation (MTHIS) methodology to generate a hierarchical set of segments based on spatial similarity of remote sensing time series. MTHIS employs the similarity of the fast Fourier transform (FFT) components of multi-seasonal time series to group pixels with similar temporal behavior into hierarchical segments at different scales. Use of the FFT allows the distinction between noise and vegetation related signals and increases the computational efficiency. The MTHIS methodology is demonstrated on the area of South Africa in an MTHIS protocol for Normalized Difference Vegetation Index (NDVI) time series. Firstly, the FFT components that express the major spatio-temporal variation in the NDVI time series, the average and annual term, are selected and the segmentation is performed based on these components. Secondly, the results are visualized by means of a boundary stability image that confirms the accuracy of the algorithm to spatially group pixels at different scale levels. Finally, the segmentation optimum is determined based on discrepancy measures which illustrate the correspondence of the applied MTHIS output with landcover-landuse maps describing the actual vegetation. In future research, MTHIS can be used to analyze the spatial and hierarchical structure of any type of remote sensing time series and their relation to ecosystem processes.     

Indx and findphrases,a system for generating indexes for ditroff documents

Creating back-of-the-book indexes is a difficult task involving intelligent and clerical processes. Programs have generally not achieved the level of intelligence required to perform the intelligent process of selecting terms for the index. Semi-automatic indexing programs perform the clerical process of preparing entries once the terms have been selected. The programs do not provide assistance in term determination and most require flooding the text with indexing commands. indx differs from other semi-automatic indexing programs mainly because it does not require the insertion of indexing commands into the text to be indexed. The method by which indx assists in the creation of an index is introduced and compared with the characteristics of the other programs. This method includes the use of a program that aids the term determination process. The design, implementation, and application of indx are presented. Areas in which indx may be improved or enhanced are identified. An index of this paper created with indx is included as an example.     

Fuel Switching in the Electricity Sector under the EU ETS: Review and Prospective

The European Union has implemented the European Union emission trading scheme (EU ETS) as an instrument to facilitate greenhouse gas (GHG) emission abatement stipulated in the Kyoto protocol. Empirical data show that in the early stages of the EU ETS, the value of a ton of CO2 has already led to emission abatement through switching from coal to gas in the European electric power sector. In the second part of this paper, an electricity generation simulation model is used to perform simulations on the switching behavior in both the first and the second trading periods of the EU ETS. In 2005, the reduction in GHG emissions in the electric power sector due to EU ETS is estimated close to 88?Mton. For the second trading period, a European Union allowance (EUA) price dependent GHG reduction curve has been determined. The obtained switching potential turns out to be significant, up to 300?Mton/year, at sufficiently high EUA prices.