Feynman-α and Rossi-α formulas with spatial and modal effects

Feynman-α and Rossi-α formulas including multiple α-modes are derived for stochastic and continuous neutron sources. The presented formalism is further developed to achieve spatial correction factors for the single α-mode point kinetics representations of the Feynman-α and Rossi-α formulas. As a natural extension of the multiple α-mode formalism, delayed neutrons are included in the Feynman-α formula. The obtained formulas are validated experimentally in a strongly heterogeneous system obeying multiple α-modes, resulting in good agreement with the presented theoretical framework.     

Long-term recovery of PCB-contaminated sediments at the Lake Hartwell superfund site: PCB dechlorination. 2. Rates and extent

This paper reports on extensive polychlorinated biphenyl (PCB) dechlorination measured in Lake Hartwell (Pickens County, SC) sediments. Vertical sediment cores were collected from 18 locations in Lake Hartwell (Pickens County, SC) and analyzed in 5-cm increments for PCB congeners. The preferential loss of meta and para chlorines with sediment depth demonstrated that PCBs in the sediments underwent reductive dechlorination after burial. Notably, ortho chlorines were highly conserved for more than 5 decades; since the first appearance of PCBs, ca. 1950-1955. These dechlorination characteristics resulted in the accumulation of lower chlorinated congeners dominated by ortho chlorine substituents. Dechlorination rates were determined by plotting the numbers of meta plus para chlorines per biphenyl molecule (mol of chlorine/mol of PCB) with sediment age. Regression analyses showed linear correlations between meta plus para chlorine concentrations with time. The average dechlorination rate was 0.094 +/- 0.063 mol of Cl/mol of PCB/yr. The rates measured using the 2001 cores were approximately twice those measured using the 2000 cores, most likely because the 2001 cores were collected only at transects O, L, and I, which had the highest rates measured in 2000. An inverse of the dechlorination rates indicated that 16.4 +/- 11.6 yr was required per meta plus para chlorine removal (ranging from 4.3 to 43.5 yr per chlorine removal). The rates determined from this study were 1-2 orders of magnitude lower than rates reported from laboratory microcosm studies using Hudson River and St. Lawrence River sediments, suggesting that dechlorination rates reported for laboratory experiments are much higher than those occurring in situ.     

Rayonnement parasite des terminaisons court-circuitées en ligne microfente et en guide d’onde coplanaire

An integral equations technique solved by the moment method associated with simple one-port model is used to analyse parasitic radiation of short circuit terminations of slotlines and coplanar waveguides. This parasitic effect is represented by a frequency-dependent normalized resistance. Theoretical results are compared to experimental ones for substrates with several dielectric constants.     

Automatic discovery of Web Query Interfaces using machine learning techniques

The amount of information contained in databases available on the Web has grown explosively in the last years. This information, known as the Deep Web, is heterogeneous and dynamically generated by querying these back-end (relational) databases through Web Query Interfaces (WQIs) that are a special type of HTML forms. The problem of accessing to the information of Deep Web is a great challenge because the information existing usually is not indexed by general-purpose search engines. Therefore, it is necessary to create efficient mechanisms to access, extract and integrate information contained in the Deep Web. Since WQIs are the only means to access to the Deep Web, the automatic identification of WQIs plays an important role. It facilitates traditional search engines to increase the coverage and the access to interesting information not available on the indexable Web. The accurate identification of Deep Web data sources are key issues in the information retrieval process. In this paper we propose a new strategy for automatic discovery of WQIs. This novel proposal makes an adequate selection of HTML elements extracted from HTML forms, which are used in a set of heuristic rules that help to identify WQIs. The proposed strategy uses machine learning algorithms for classification of searchable (WQIs) and non-searchable (non-WQI) HTML forms using a prototypes selection algorithm that allows to remove irrelevant or redundant data in the training set. The internal content of Web Query Interfaces was analyzed with the objective of identifying only those HTML elements that are frequently appearing provide relevant information for the WQIs identification. For testing, we use three groups of datasets, two available at the UIUC repository and a new dataset that we created using a generic crawler supported by human experts that includes advanced and simple query interfaces. The experimental results show that the proposed strategy outperforms others previously reported works.     

Three-dimensional reconstruction of a plant dictyosome from series of ultrathin sections using computer image processing

A single dictyosome from an actively secreting ovary gland cell of Aptenia cordifolia has been reconstructed in 3-D from a series of twenty-nine electron micrographs by computer image processing. The reconstruction is presented under different viewing angles in the form of shaded perspective displays. From these displays the entire dictyosome, surrounded by numerous vesicles, appears to be more a spherical than a flat body. The plate-like region of the dictyósome is demonstrated when only a portion of the electron micrographs is used for the image processing, leading to ‘cut-off’ displays. Since some upper planes were removed, such ‘cut-off’ displays revealed both tubular connections between cisternae of the dictyosome and the neighbouring endoplasmic reticulum as well as tubular continuities between adjacent Golgi cisternae within the same stack. Possible consequences of both types of interconnections on transport and processing of proteins and glycoproteins are discussed.     

Determination of the sticking coefficient of energetic hydrocarbon molecules by molecular dynamics

The sticking coefficient of hydrocarbon species is a key quantity that influences the growth process of amorphous hydrocarbon layers. To extend the very limited database for low impact energies, classical molecular dynamics simulations were performed, determining the sticking coefficients of CH_x (x = 0 … 4) with kinetic energies between 5 and 100 eV. Similar simulations are performed with hydrogen substituted by deuterium. Additionally, analytical formulas are presented that fit the data very well and can be used to interpolate the simulation results.     

Subcarrier and Power Allocation for the Downlink of Multiuser OFDM Transmission

In this paper, a new algorithm for subcarrier and power allocation for the downlink of multiuser OFDM transmission is presented. The proposed algorithm is more stable and it offers a lower complexity and better performance than previous existing algorithms. Khalid El Baamrani was born in Ouarzazate, Morocco in 1976. He received the License degree (equiv. B.A.) in electronic engineering from the University of Cadi Ayyad, Marrakech, Morocco, in 1998, the D.E.S.A. (equiv. M.A) in electrical engineering from the University of CadiAyyad, Marrakech, Morocco, in 2000, the certificate in engineering of the data-processing networks and telecommunications from the national institute of posts and telecommunications, Rabat, Morocco in 2002 and the Ph.D. degree at University of Cadi Ayyad, Marrakech, Morocco in 2005. His research interests include multicarrier modulation, communication theory, multiuser information theory, OFDM and DSL systems. Victor P. Gil Jiménez received the B. Eng. in Telecommunications with honors from University of Alcalá in 1998 and the M. Eng. in Telecommunications and the PhD. degree both from the University Carlos III de Madrid in 2001 and 2005, respectively. He is with the Department of Signal Theory and Communications at the University Carlos III de Madrid as an Assistant Professor. He worked at the Spanish Antarctica Base in 1999 as Communications Staff. He visited University of Leeds and Chalmers Technical University in 2003 and 2004 respectively. His research interests include multicarrier communications and signal processing for wireless systems. Ana Garcia Armada received the Telecommunication Engineer degree and the Ph.D in Electrical Engineering both from the Polytechnic University of Madrid (Spain) in 1994 and 1998, respectively. She is currently working as an Associate Professor at the University Carlos III de Madrid, where she has occupied several management positions. She has participated in several national and international research projects, most of them related to OFDM. She is coauthor of four books on wireless communications and signal processing. She has published 13 papers in international journals and more than 40 papers in conferences. She has contributed to international organizations such as ITU and ETSI. She has performed research stays in ESA-ESTEC, Kansas University, Stanford University and Bell Labs. Her research interests are simulation of communication systems, multicarrier and MIMO techniques.     

Plug-plug kinetic capillary electrophoresis: method for direct determination of rate constants of complex formation and dissociation

We present a method for direct determination of rate constants of complex formation, k(on), and dissociation, k(off). The method is termed plug-plug kinetic capillary electrophoresis (ppKCE). To explain the concept of the method, we consider the formation of a noncovalent complex C between molecules A and B; A is assumed to migrate slower in electrophoresis than B. In ppKCE, a short plug of A is injected into a capillary, followed by a short plug of B. When a high voltage is applied, the electrophoretic zone of B moves through that of A, allowing for the formation of C. When the zones of A and B are separated, C starts dissociating. The features of the resulting electropherogram are defined by both binding and dissociation. We developed a unique mathematical approach that allows finding k(on) and k(off) from a single electropherogram without nonlinear regression analysis. The approach uses algebraic functions with the only input parameters from electropherograms being areas and migration times of electrophoretic peaks. In this work, we explain theoretical bases of ppKCE and prove the principle of the method by finding k(on) and k(off) for a protein-ligand complex. The unique capability of the method to directly determine both k(on) and k(off) along with its simplicity make ppKCE highly attractive to a broad community of molecular scientists.     

代价敏感分类器的比较研究

简要地回顾了代价敏感学习的理论和现有的代价敏感学习算法.将代价敏感学习算法分为两类,分别是直接代价敏感学习和代价敏感元学习,其中代价敏感元学习可以将代价不敏感的分类器转换为代价敏感的分类器.提出了一种简单、通用、有效的元学习算法,称为经验阈值调整算法(简称ETA).评估了各种代价敏感元学习算法和ETA的性能.ETA几乎总是得到最低的误分类代价,而且它对误分类代价率最不敏感.还得到了一些关于元学习的其它有用结论.     

A low-cost method to produce superhydrophobic polymer surfaces

Here, we introduce a novel and inexpensive template-based structuring process to create superhydrophobic polymer surfaces adapted from the naturally occurring micro/nano structured surfaces found on the superhydrophobic leaves of the quaking aspen tree. Electroformed nanocrystalline nickel coupons were sandblasted and chemically etched to create a negative reproduction of the aspen leaf surface structure. These nanocrystalline nickel samples were then employed as re-useable templates and pressed against various polymers at elevated temperatures, transferring the desired superhydrophobic structure to their surfaces. This structuring process resulted in water contact angles above 150° and tilt angles below 5° for polyethylene, polypropylene and polytetrafluoroethylene samples. In addition, the effects of temperature, water drop size and surfactant concentration on these pressed polymer surfaces were investigated to assess potential application limitations for these surfaces.