bluuebunny/crossref_metadata_2025 huggingface dataset:
Prenatal 3‐dimensional sonographic and MRI findings in omphalocele–exstrophy–imperforate anus–spinal defects complex
Authors: Chen Chih‐Ping , Chang Tung‐Yao , Liu Yu‐Peng , Tsai Fuu‐Jen , Chien Shu‐Chin , Tsao Chien‐Ming , Yang Hsiao‐Bai , Wang Wayseen
Published: September 2007

We describe the second‐trimester 3D sonographic and MRI findings of omphalocele–exstrophy–imperforate anus–spinal defects (OEIS) complex. We suggest that fetal 3‐dimensional sonography with tomographic ultrasound imaging and MRI are useful adjuncts to conventional 2‐dimensional sonography in the prenatal diagnosis of OEIS complex. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2008
Changes in liquid‐holding capacity, water distribution and microstructure during chill storage of smoked salmon
Authors: Løje Hanne , Jensen Kristina N , Hyldig Grethe , Nielsen Henrik H , Nielsen Jette
Published: September 2007

BACKGROUND: During recent years, increases in liquid loss and soft texture in cold smoked salmon have been reported, possibly due to increased lipid content and a change in muscle structure. These problems can lead to downgrading of the product. This study aimed to investigate the influence of raw material composition and chill storage on quality parameters of cold smoked salmon.

RESULTS: Initial smoked fish had a higher liquid‐holding capacity (LHC) than samples stored for 20 days. Large fish lost more liquid than small fish. The difference in LHC was consistent with a change in water distribution, which could indicate denaturation of muscle protein. Studies of the microstructure showed the influence of both processing and chill storage. An indication of lipid released from the cells was seen after 20 days of chill storage, which could be related to the reduced LHC at that time.

CONCLUSION: Both raw material composition and chill storage affected the quality parameters of smoked salmon. This study has improved knowledge about the relationships between muscle structure, liquid‐holding properties and water distribution in smoked salmon. Copyright © 2007 Society of Chemical Industry
Left‐Sided microsatellite unstable colorectal cancers show less frequent methylation of hMLH1 and CpG island methylator phenotype than right‐sided ones
Authors: Tanaka Junichiro , Watanabe Toshiaki , Kanazawa Takamitsu , Tada Tomohiro , Kazama Yoshihiro , Tanaka Toshiaki , Nagawa Hirokazu
Published: September 2007

Condensed abstract

We compared the methylation status of several loci between right‐sided and left‐sided colorectal cancers (CRCs). To the best of our knowledge, this is the first to report that left‐sided CRCs show significantly less frequent methylation at several loci and CpG island methylator phenotype (CIMP) than right‐sided ones.

Background and Objectives

MSI CRC occurs in 10–20% of unselected series of patients with CRC. Somatic hMLH1 promoter methylation is reported to cause MSI in sporadic cases. Many researchers report that MSI CRCs are more frequently located in the right‐side colon than MSS CRCs. Though the number is very small, some MSI CRCs are located in the left‐side colorectum. We focused on the existence of left‐sided MSI CRCs and investigated whether they arise through hMLH1 methylation as they do in right‐sided ones.

Methods

Thirty‐eight sporadic MSI CRCs were included in the study. The methylation status of the promoter of hMLH1, p16, MINT1, 2 and 31 were examined and the proportions of methylated samples for each locus were compared.

Results

The left‐sided group showed significantly less frequent methylation in hMLH1, p16, MINT1, 2 and 31. The frequency of CIMP+ samples in the left‐sided group was significantly lower than the right‐sided group.

Conclusions

Left‐sided MSI CRCs show significantly less frequent methylation of hMLH1. They also showed significantly less frequent occurrence of CIMP+ than right‐sided ones. It is possible that left‐sided MSI CRCs differ from the right‐sided ones in the way of acquiring MSI. J. Surg. Oncol. 2007;96:611–618. © 2007 Wiley‐Liss, Inc.
Compartment syndrome of the leg associated with lithotomy position for cytoreductive surgery
Authors: Zappa Luis , Sugarbaker Paul H.
Published: September 2007

Background

Compartment syndrome is seen in patients who have ischemic damage to muscle that is contained within a fascial compartment. A pathologic cycle is initiated when tissue injury produces swelling and compromises muscle perfusion. Patients undergoing cytoreductive surgery combined with intraperitoneal chemotherapy are required to be in the lithotomy position for many hours. Compartment syndrome can develop necessitating fasciotomy.

Methods

In a study of 473 operative procedures to perform cytoreductive surgery and intraperitoneal chemotherapy, eight patients required fasciotomy on an emergency basis to treat compartment syndrome and were recorded in a prospective database over a 4‐year time period.

Results

During the hospitalization five of the eight patients developed venous thrombotic complications. In order to prevent movement of the patient on the operating table during steep Trendelenburg position, shoulder braces were used in the subsequent 250 patients and no episodes of compartment syndrome occurred.

Conclusion

Compartment syndrome in patients undergoing cytoreductive surgery may be related to changes in position on the operating table induced by steep Trendelenburg position. Minimizing this change in position has reduced the likelihood of developing Compartment syndrome. J. Surg. Oncol. 2007;96:619–623. © 2007 Wiley‐Liss, Inc.
Majorization and distances in trees
Authors: Dahl Geir
Published: September 2007

We investigate distance vectors in trees and introduce a new center concept based on the notion of majorization and discuss relations to location theory. For a tree T and a vertex v ∈ T, we define the distance vector d(v,·) = (d(v,w) w ∈ T), where d(v,w) denotes the distance between v and a vertex w. We characterize whenever d(u,·) is weakly majorized by d(v,·) for adjacent vertices u and v. Moreover, we introduce a new center concept in trees, the majorization‐center, and relate this to known centers and the set of balance vertices. © 2007 Wiley Periodicals, Inc. NETWORKS, Vol. 50(4), 251–257 2007
An efficient linear programming solver for optimal filter synthesis
Authors: Ren Jihong , Greif Chen , Greenstreet Mark R.
Published: September 2007

We consider the problem of l∞ optimal deconvolution arising in high data‐rate communication between integrated circuits. The optimal deconvolver can be found by solving a linear program for which we use Mehrotra's interior‐point approach. The critical step is solving the linear system for the normal equations in each iteration. We show that this linear system has a special block structure that can be exploited to obtain a fast solution technique whose overall computational cost depends mostly on the number of design variables, and only linearly on the number of constraints. Numerical experiments validate our findings and illustrate the merits of our approach. Copyright © 2007 John Wiley & Sons, Ltd.
More on extremal ranks of the matrix expressions A − BX ± X*B* with statistical applications
Authors: Liu Yonghui , Tian Yongge
Published: September 2007

Through a Hermitian‐type (skew‐Hermitian‐type) singular value decomposition for pair of matrices (A, B) introduced by Zha (Linear Algebra Appl. 1996; 240:199–205), where A is Hermitian (skew‐Hermitian), we show how to find a Hermitian (skew‐Hermitian) matrix X such that the matrix expressions A − BX ± X*B* achieve their maximal and minimal possible ranks, respectively. For the consistent matrix equations BX ± X*B* = A, we give general solutions through the two kinds of generalized singular value decompositions. As applications to the general linear model {y, Xβ, σ2V}, we discuss the existence of a symmetric matrix G such that Gy is the weighted least‐squares estimator and the best linear unbiased estimator of Xβ, respectively. Copyright © 2007 John Wiley & Sons, Ltd.
A multilevel Crout ILU preconditioner with pivoting and row permutation
Authors: Mayer Jan
Published: September 2007

In this paper, we present a new incomplete LU factorization using pivoting by columns and row permutation. Pivoting by columns helps to avoid small pivots and row permutation is used to promote sparsity. This factorization is used in a multilevel framework as a preconditioner for iterative methods for solving sparse linear systems. In most multilevel incomplete ILU factorization preconditioners, preprocessing (scaling and permutation of rows and columns of the coefficient matrix) results in further improvements. Numerical results illustrate that these preconditioners are suitable for a wide variety of applications. Copyright © 2007 John Wiley & Sons, Ltd.
The character of power output from utility‐scale photovoltaic systems
Authors: Curtright Aimee E. , Apt Jay
Published: September 2007

Power produced by utility‐scale solar photovoltaic (PV) systems has fluctuations on both short and long time scales. Power spectral density (PSD) analysis provides information on the character of these power fluctuations. Examination of the correlation and step size of the power output between several PV sites within a multi‐site system allows assessment of geographic diversification for addressing intermittency. Both techniques provide insight into the characteristics of firm power and/or demand response required to accommodate large‐scale PV deployment. Copyright © 2007 John Wiley & Sons, Ltd.
Synthesis and electrochemical behavior of linear oligo(ferrocenylsilane) and hyperbranched poly(ferrocenylsilane)
Authors: Huo Jia , Wang Li , Yu Hao‐Jie , Deng Li‐Bo , Zhou Jun‐Feng , Yang Qiang
Published: September 2007

Linear oligo(ferrocenylsilane) and hyperbranched poly(ferrocenylsilane) (LOFS and HPFS) were synthesized by polycondensation of 1,1′‐dilithioferrocene (FcLi2) with dimethyldichlorosilane (Me2SiCl2) and FcLi2 with methyltrichlorosilane (MeSiCl3) in THF under different conditions, respectively. The electrochemical behaviors of LOFS and HPFS in different solvents, such as THF, CH2Cl2, and CHCl3, were investigated systematically by means of cyclic voltammetry (CV). The influences of the solvent, structure of polymer, and scan rate on electrochemical behavior of poly(ferrocenylsilane) solutions are discussed. It is found that ΔE1/2 decreases with the fall of solvent polarity apart from the solvent donor effect and increases with the increase of the acceptor number (AN) of the solvent. More interestingly, the structure of polymer imposes greatly on the interaction between ferrocene units. According to the result, the mechanism of stepwise oxidation of the ferrocene units was proposed, that is, the different conformations of polymers, attaching to electrode surface, before and after oxidized resulted in the stepwise oxidation of ferrocene groups along a chain. Kinetic parameters from CVs indicate that the electrode processes are controlled by both the electrode reaction and mass diffusion and the electrochemical irreversibility of poly(ferrocenylsilane) solutions may be ascribed to the lower electron exchange efficiency on the electrode surface. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2880–2889, 2007
Comparison of glass transition and interpretation on miscibility in blends of amorphous poly(vinyl methyl ether) with highly crystallizable versus less‐crystallizable polyesters
Authors: Chiang Wan‐Jing , Woo E. M.
Published: September 2007

Various phase behavior of blends of poly(vinyl ether)s with polyesters of two types (highly crystalline and less crystalline with different main‐chains) were examined using differential scanning calorimetry (DSC) and optical microscopy (OM). Effects of varying the main‐chain polarity of the constituent polyesters on the phase behavior of the blends were analyzed. Miscibility in PVME/polyester blends was found only in polyesters with backbone CH2/CO ratio = 3.5 to 7.0). Tg‐composition relationships for blends of PVME with highly crystalline polyesters (PBA, PHS) were found to differ significantly from those for PVME blends with less‐crystalline polyesters (PTA, PEAz). Crystallinity of highly crystalline polyester constituents in blends caused significant asymmetry in the Tg‐composition relationships, and induced positive deviation of blends' Tg above linearity; on the other hand, blends of PVME with less crystalline polyesters exhibit typical Fox or Gordon‐Taylor types of relationships. The χ parameters for the miscible blends were found to range from −0.17 to −0.33, reflecting generally weak interactions. Phase behavior was analyzed and compared among blends of PVME with rapidly crystallizing vs. less‐crystallizing polyesters, respectively. Effects of polyesters' crystallinity and structures on phase behavior of PVME/polyester blends are discussed. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2899–2911, 2007
Microcellular processing and relaxation of poly(ether ether ketone)
Authors: Wang Dong , Gao Hong , Jiang Wei , Jiang Zhenhua
Published: September 2007

The semicrystalline microcellular closed‐cell foams are prepared by a two‐stage batch foaming process from poly(ether ether ketone) and characterized by scanning electronic microscopy. It can be observed that there are two kinds of cells with obviously different cellular sizes in the same transect and the distribution of larger cells (about 7 μm) looks like sandwich. The effects of foaming temperatures and transfer times on the cellular sizes and cell densities of porous materials were discussed. Particular emphasis was given to the effects of crystalline on the microcellular morphology. The relaxation mechanism of microcellular materials was systemically investigated by dynamic mechanics analysis. A plain on the storage modulus curve before Tg was observed due to the densification of cells. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2890–2898, 2007
Thermorheological complexity of poly(methyl methacrylate)/poly(vinylidene fluoride) miscible polymer blend: Terminal and segmental levels
Authors: Es‐Haghi S. Shams , Yousefi A. A. , Oromiehie A.
Published: September 2007

Oscillatory shear rheometry data for a miscible blend of 20 wt % poly(vinylidene fluoride) (PVDF) in poly(methyl methacrylate) (PMMA) shows breakdown of time–temperature superposition for this blend. A comparison between glass transition temperature which PMMA chains sense in the blend and effective glass transition temperature of this component indicates that, the Lodge–McLeish model can describe terminal dynamics of PMMA. In addition, terminal dynamics of PVDF chains in the blend is similar to that of its pure state in agreement with the mentioned model. At segmental level, dynamic mechanical thermal analysis of four wholly amorphous blends suggests that cooperativity of molecular motions decreases upon addition of 30 and 40 wt % PVDF to PMMA. This behavior has been confirmed via calculation of degree of fragility which presumably is attributed to strong tendency of PVDF chains to self‐association rather than inter‐association with PMMA chains according to the FTIR results. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2860–2870, 2007
Templated nanostructured PS‐b‐PEO nanotubes
Authors: Chen Jiun‐Tai , Zhang Mingfu , Yang Ling , Collins Margaret , Parks Jim , Avallone Armando , Russell Thomas P.
Published: September 2007

With anodic aluminum oxide (AAO) membranes as wetting templates, nanotubes of the cylinder‐forming polystyrene‐block‐poly(ethylene oxide) (PS‐b‐PEO) copolymer were generated. The PS‐b‐PEO solution was introduced into the cylindrical nanopores of an AAO membrane by capillary force and polymeric nanotubes formed after solvent evaporation. Because of the water solubility of the cylindrical PEO microdomains and the orientation of the cylindrical PEO microdomains with respect to the nanotube walls, the nanotubes were permeable to aqueous media. PS‐b‐PEO nanotubes were also prepared on the interior walls of amorphous carbon nanotubes (a‐CNTs). Because of the unique water permeability of the PEO microdomains, an avenue for functionalizing the interior of the a‐CNTs is enabled. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2912–2917, 2007
Vacancy–interstitial annihilation in titanomagnetite by thermal annealing
Authors: Walz F. , Brabers V. A. M. , Brabers J. H. V. J. , Kronmüller H.
Published: September 2007

This paper is concerned with the annealing kinetics of point defects giving rise – in the presence of Ti4+‐induced internal stresses – to pronounced, thermally activated magnetic after‐effects (MAEs) near 450, 200 and 65 K in single‐crystalline titanomagnetites Fe3–x –Δ Tix O4 of composition 0.1 < x < 0.3 and Δ < 0.005. These relaxation processes have been associated with reorientations of anisotropic point defect configurations of Ti4+‐bound octahedral (B‐site) vacancies (450 K), Fe2+ interstitials (200 K) and a specific mode of stress‐reducing electron hopping (65 K). In order to check the developed model conceptions, crystals have been systematically annealed and the induced variations of the MAE spectra carefully analysed with respect to the underlying defect kinetics. As an important result, the common recovery of the 450 K and 200 K MAEs, in one stage near T > 1000 K, yielded coincident kinetics of reaction order γ = 2 and recombination enthalpy Q = 2.45 ± 0.05 eV – as being compatible with bimolecular defect (vacancy) – anti‐defect (interstitial) recombination. The delayed recovery of the 65 K peak (at T ≥ 1100 K) points to a stress‐sensitive relaxation mechanism, being deactivated only with the final annihilation of stress‐producing anisotropic defects. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface chemical and electronic properties of plasma‐treated n‐type Al0.5Ga0.5N
Authors: Cao X. A. , Piao H. , Li J. , Lin J. Y. , Jiang H. X.
Published: September 2007

The effects of plasma treatment on the surface properties of Si‐doped Al0.5Ga0.5N were studied by X‐ray photoelectron spectroscopy and metal contact measurements. Plasma treatment resulted in a N‐deficient nonstoichiometric AlGaN surface with an increased O concentration and large red shifts of photoelectron peaks. The red shifts remained after removal of the surface oxide, indicating a downward shift of the surface Fermi level as a result of ion‐induced compensating defects. Pre‐metal plasma treatment led to more rectifying electrical characteristics of Ti/Al/Ti/Au contacts. Current–voltage characterization at elevated temperatures revealed strong compensating effects of the plasma damage in Al0.5Ga0.5N even at 300 °C. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simple fabrication of nanoporous films on ZnO for enhanced light emission
Authors: Bang J. , Kim K. , Mok S. , Ren F. , Pearton S. J. , Baik K. H. , Kim S. H. , Kim J. , Shin K.
Published: September 2007

High density nanoporous patterns were imprinted on bulk ZnO single‐crystal substrates. The nanostamps were prepared via replication from nanoporous anodized alumina. Using the nanoimprinting technique, nanopatterns were successfully transferred onto the ZnO surface. Here we demonstrate that the light emitting efficiency of ZnO is highly enhanced through the simple nano‐texturing. This simple method is applicable to any other light emitting diodes where the antireflective surface coating is desirable. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Carbon nanowire‐based temperature sensor
Authors: Zaitsev Alexander M. , Levine Alfred M. , Zaidi Sohail H.
Published: September 2007

A temperature sensor based on an array of carbon nanowires written by a 30 keV Ga+ focused ion beam on diamond substrate has been developed. The temperature sensitivity of the electrical conductuctance between the nanowires is explained by the thermal activation of charge carriers in a heterostructure graphite‐diamond over an energy barrier of 0.24 eV. The sensor shows an exponential increase of current with temperature at a rate of 0.1 dB/°C in the temperature range from 40 to 140 °C. The advantages of the novel carbon nanowire sensor are light blindness, compatibility with carbon nanotechnology, reproducibility and simplicity of fabrication. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of Carbon 1s Core Ionization Energies in Saturated Molecules
Authors: Cao Chenzhong
Published: September 2007

The Slater‐like model was established to calculate the carbon 1s core ionization energies in saturated molecules. Using the atomic Electron Affinity (EA), average valence‐shell electron energy EI and polarizability α as parameters, the charge effect, the relaxation effect, and the electrostatic field effect were evaluated for the C 1s core ionization energies in saturated molecules. The charge effect was scaled by electronegativity difference (the difference in EA and the difference in EI between the carbon atom that is being ionized and its adjacent atoms). The relaxation effect (induced dipole) was scaled by the charge on the ionized carbon atom together with the polarizability of all other atoms in the molecules. The electrostatic field effect was scaled using the charges of the other atoms in molecular backbone divided by the distance between the ionized carbon atom and the other backbone atom. Furthermore, the electrostatic relaxation effect ΔSi of C 1s electron was expressed by the above three effects. By introducing the ΔSi into the Slater model, a Slater‐like model was obtained to calculate the C 1s core ionization energy E1,C of halomethane and more complex molecules, whose correlation coefficient r is 0.99955 and the average absolute error between the calculated and the experimental values for 63 compounds is only 0.079 eV. Also the crosscorrelation was tested by the Leave‐One‐Out (LOO) crossvalidation method, and the correlation coefficient rcv=0.99941 and an average absolute error of 0.091 eV between the predicted and the experimental values were obtained. Using the obtained model, some C 1s electron ionization energies were predicted, and the results were in agreement with the experimental values. Application of the developed approach to other systems was also tested.
A new method of accurate pKb determinations for some organic amines
Authors: Jia Zhao‐Kun , Zhang Shu‐Fang , Zhou Zheng‐Yu , Zhang An‐Guo , Hou Rui‐Yan
Published: September 2007

The accurate pKb determinations for some amines have been investigated using the combination of the extended clusters‐continuum model with the polarizable continuum solvation model. The formation of molecular clusters by means of the amines wrapped up with water molecules leads to the weakness of the mutual function between the polar solvents and the amines, and, hence, the accuracy of pKb has been enhanced by using a coherent and well‐defined approach without external approximations or experimental data. The calculations are performed at the HF/6‐311++G(d, p) level and agreed well with experimental data because electron correlation effect cancels mutually in the calculated value of ΔG which is not an absolute value, but a relative value. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Theoretical study of the oxidative polymerization of aniline with peroxydisulfate: Tetramer formation
Authors: Ćirić‐Marjanović Gordana , Trchová Miroslava , Stejskal Jaroslav
Published: September 2007

Semi‐empirical quantum chemical study of the oxidative polymerization of aniline with ammonium peroxydisulfate, in aqueous solutions without added acid, has been based on the MNDO‐PM3 computations of thermodynamic, redox, and acid–base properties of reactive species and the intermediates, combined with the MM2 molecular mechanics force‐field method and conductor‐like screening model of solvation. The main reaction routes of aniline tetramerization are proposed. The regioselectivity of the formation of aniline tetramers by redox and electrophilic aromatic substitution reactions is analyzed. It was proved that the linear NC4 coupled tetra‐aniline is formed as a dominant product by three different pathways: comproportionation redox reaction between N‐phenyl‐1,4‐benzoquinonediimine and 4‐aminodiphenylamine, the one‐electron oxidation of aniline with its half‐oxidized NC4 coupled trimer, and the electrophilic aromatic substitution reaction of aniline with fully oxidized NC4 coupled trianiline nitrenium cation. The electrophilic aromatic substitution reaction of the NC4 coupled aniline trimer with aniline nitrenium cation, as well as the oxidation of aniline with half‐oxidized branched trimer, lead to the branched aniline tetramers. The competing character of different tetramerization routes is highlighted. The oxidative intramolecular cyclization of branched oligoanilines and polyaniline, leading to the generation of substituted phenazine units, has been predicted to accompany the classical routes of the polymerization of aniline. Various molecular (branched vs. linear) oligomeric structures produced at different level of acidity during the course of polymerization and their impact on the formation of supramolecular structures of conducting polyaniline (nanorods and nanotubes vs. granular morphology), are discussed. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Random mappings with exchangeable in‐degrees
Authors: Hansen Jennie C. , Jaworski Jerzy
Published: September 2007

In this article we introduce a new random mapping model, $T_n^{\hat D}$, which maps the set {1,2,…,n} into itself. The random mapping $T_n^{\hat D}$ is constructed using a collection of exchangeable random variables $\hat{D}_1, \ldots.,\hat{D}_n$ which satisfy $\sum_{i=1}^n\hat{D}_i=n$. In the random digraph, $G_n^{\hat D}$, which represents the mapping $T_n^{\hat D}$, the in‐degree sequence for the vertices is given by the variables $\hat{D}_1, \hat{D}_2, \ldots, \hat{D}_n$, and, in some sense, $G_n^{\hat D}$ can be viewed as an analogue of the general independent degree models from random graph theory. We show that the distribution of the number of cyclic points, the number of components, and the size of a typical component can be expressed in terms of expectations of various functions of $\hat{D}_1, \hat{D}_2, \ldots, \hat{D}_n$. We also consider two special examples of $T_n^{\hat D}$ which correspond to random mappings with preferential and anti‐preferential attachment, respectively, and determine, for these examples, exact and asymptotic distributions for the statistics mentioned above. © 2007 Wiley Periodicals, Inc. Random Struct. Alg., 2008
Analyzing linear mergers
Authors: Dvir Zeev , Raz Ran
Published: September 2007

Mergers are functions that transform k (possibly dependent) random sources (distributions) into a single random source, in a way that ensures that if one of the input sources has min‐entropy rate δ then the output has min‐entropy rate close to δ. Mergers have proven to be a very useful tool in explicit constructions of extractors and condensers, and are also interesting objects in their own right. In this work we give a refined analysis of the merger constructed by [Raz, STOC'05] (based on [Lu, Reingold, Vadhan, and Wigderson, STOC'03 pp. 602–611, 2003]). Our analysis uses min‐entropy instead of Shannon's entropy to derive tighter results than the ones obtained in [Raz STOC'05].

We show that for every constant r and k it is possible to construct a merger that takes as input k strings of length n bits each, and outputs a string of length n/r bits, such that if one of the input sources has min‐entropy b, the output will be close to having min‐entropy b/(r + 1). This merger uses a constant number of additional uniform bits. One advantage of our analysis is that b (the min‐entropy of the “good” source) can be as small as a constant (this constant depends on r and k), while in the analysis given in [Raz STOC'05], b is required to be linear in n. © 2007 Wiley Periodicals, Inc. Random Struct. Alg., 2008
Sampling subproblems of heterogeneous Max‐Cut problems and approximation algorithms
Authors: Drineas Petros , Kannan Ravi , Mahoney Michael W.
Published: September 2007

Recent work in the analysis of randomized approximation algorithms forNP‐hard optimization problems has involved approximating the solution to a problem by the solution of a related subproblem of constant size, where the subproblem is constructed by sampling elements of the original problem uniformly at random. In light of interest in problems with a heterogeneous structure, for which uniform sampling might be expected to yield suboptimal results, we investigate the use of nonuniform sampling probabilities. We develop and analyze an algorithm which uses a novel sampling method to obtain improved bounds for approximating the Max‐Cut of a graph. In particular, we show that by judicious choice of sampling probabilities one can obtain error bounds that are superior to the ones obtained by uniform sampling, both for unweighted and weighted versions of Max‐Cut. Of at least as much interest as the results we derive are the techniques we use. The first technique is a method to compute a compressed approximate decomposition of a matrix as the product of three smaller matrices, each of which has several appealing properties. The second technique is a method to approximate the feasibility or infeasibility of a large linear program by checking the feasibility or infeasibility of a nonuniformly randomly chosen subprogram of the original linear program. We expect that these and related techniques will prove fruitful for the future development of randomized approximation algorithms for problems whose input instances contain heterogeneities. © 2007 Wiley Periodicals, Inc. Random Struct. Alg., 2008
Direct Low‐Temperature Synthesis of Rutile Nanostructures in Ionic Liquids
Authors: Kaper Helena , Endres Frank , Djerdj Igor , Antonietti Markus , Smarsly Bernd M. , Maier Joachim , Hu Yong‐Sheng
Published: September 2007

The direct synthesis of crystalline titania nanorods by sol–gel chemistry in a special ionic liquid is reported. Unexpectedly, the high‐temperature modification, rutile, is obtained directly under ambient conditions. X‐ray diffraction and high‐resolution transmission electron microscopy measurements support the highly crystalline and structural quality of the sample. The phase‐directing property of the ionic liquids is attributable to the imide group in the counter ion, which exhibits strong interaction with specific rutile faces. Lithium insertion experiments were performed and revealed high and reversible loading capacities of up to 200 mAh g−1.
Hybridization Kinetics and Thermodynamics of DNA Adsorbed to Individually Dispersed Single‐Walled Carbon Nanotubes
Authors: Jeng Esther S. , Barone Paul W. , Nelson John D. , Strano Michael S.
Published: September 2007

Hybridization of DNA adsorbed to single‐walled carbon nanotubes in solution has much slower kinetics than free solution DNA, and can be detected through a blue shift in the near‐infrared nanotube fluorescence. Adsorption of the receptor DNA strand to the nanotube surface is consistent with models of polyelectrolyte adsorption on charged surfaces, introducing both entropic (46.8 cal mol−1 K−1) and activation energy (20.4 kcal mol−1) barriers to the hybridization, which are greater than free solution values (31.9 cal mol−1 K−1 and 12.9 kcal mol−1) at 25 °C. The increased hybridization barriers on the nanotube result in exceedingly slow kinetics for hybridization with t1/2=3.4 h, compared to the free solution value of t1/2=4 min. These results have significant implications for nanotube and nanowire biosensors.
A multiple layer model to compare RNA secondary structures
Authors: Allali Julien , Sagot Marie‐France
Published: September 2007

We formally introduce a new data structure, called MiGaL for ‘Multiple Graph Layer’, composed of various graphs linked together by relations of abstraction/refinement. The new structure is useful for representing information that can be described at different levels of abstraction, each level corresponding to a graph. We then propose an algorithm for comparing two MiGaLs. The algorithm performs a step‐by‐step comparison starting with the most ‘abstract’ level. The result of the comparison at a given step is communicated to the next step using a special colouring scheme. MiGaLs represent a very natural model for comparing RNA secondary structures that may be seen at different levels of detail, going from the sequence of nucleotides, single or paired with another to participate in a helix, to the network of multiple loops that is believed to represent the most conserved part of RNAs having similar function. We therefore show how one can use MiGaLs to very efficiently compare two RNAs of any size at different levels of detail. Copyright © 2007 John Wiley & Sons, Ltd.
Anlagendynamik, Belastungen und Entwurfanforderungen von Offshore‐Windenergieanlagen und deren Tragstruktur
Authors: Kühn Martin , Argyriadis Kimon
Published: September 2007

Die Auslegung der Tragstrukturen von Offshore‐Windenergieanlagen stellt eine neue und anspruchsvolle technische und wirtschaftliche Herausforderung dar. Der vorliegende Übersichtsartikel präsentiert in kompakter Form einige wesentliche Aspekte der Eigenschaften von Offshore‐WEA, deren Lastannahmen, Berechnungsverfahren und Richtlinien. Beispiele teils fiktiver, teils realer Offshore‐Windenergieanlagen von 1,5 bis 5 MW Leistung werden zur Veranschaulichung der Bedeutung einer die Maschine und die Tragstruktur umfassenden integrierten Betrachtung, des Einflusses der lokalen Standortbedingungen und von Besonderheiten in der Berechnung von Extrem‐ sowie Betriebsfestigkeitsbelastungen verwendet. Abschließend wird ein Ausblick auf weitere Entwicklungen gegeben.
Die neue Rheinbrücke Wesel – Entwurfsplanung und Ausschreibung
Authors: Gebert Gregor , Bohm Stefan , Sprinke Peter , Hamme Markus , Löckmann Hans , Reinsch Helmut
Published: September 2007

Die neue Rheinbrücke Wesel im Zuge der B 58n befindet sich zur Zeit in Bau. Das insgesamt 773 m lange Bauwerk wird als einhüftige Schrägseilbrücke mit einer Hauptöffnung von 335 m ausgeführt. Mit seinem 130 m hohen Pylon wird das Bauwerk die flache Rheinlandschaft nachhaltig prägen. Die Brückenkonstruktion unterteilt sich in den 409 m langen Stahlüberbau der Strombrücke und die 364 m lange Spannbetonbrücke über das linksrheinische Vorland. Beide Abschnitte sind biegesteif miteinander gekoppelt. Der Aufsatz beschreibt die statischen, konstruktiven und gestalterischen Besonderheiten des Bauwerks aus der Sicht der Entwurfsverfasser und geht auf die Ausschreibung und Vergabe dieses herausragenden Bauvorhabens ein.
Increased binding potential of [11C]raclopride during unilateral continuous microinjection of nicotine in rat striatum observed by positron emission tomography
Authors: Tajima Toshihisa , Hatano Kentaro , Suzuki Mitsuru , Ogawa Mikako , Sakiyama Yojiro , Kato Takashi , Endo Hidetoshi , Miura Hisayuki , Matsubara Michitaka , Ito Kengo
Published: September 2007

Nicotine injections and nicotine skin patches significantly improve attention, memory, and learning in Alzheimer's disease. In animal studies, nicotine improves the performance of various memory‐related tasks, an effect that is thought to be mediated by the neuronal dopaminergic system as systemic administration of nicotine decreased [11C]raclopride binding in the anesthetized state. Since high doses of systemically administered nicotine are harmful, we administrated it directly into the rat striatum via microdialysis. We then examined the acute effects of continuous central administration of high doses of nicotine on striatal dopamine concentrations by measuring [11C]raclopride binding by positron emission tomography. The concentration of dopamine in the dialysates was significantly increased from basal levels when microdialysis with 100 mM nicotine was initiated. However, contrary to expectations, the binding potential (BP) of [11C]raclopride in the nicotine‐perfused striatum was significantly higher than that in control striatum. Preinjection of mecamylamine (3 mg/kg), a nicotinic antagonist, had no effect on either extracellular dopamine levels or on the BP of [11C]raclopride. These findings suggest that the high dose of local nicotine administration induced mecamylamine‐insensitive local increases in extracellular dopamine, but might have decreased the total amount of extracellular dopamine in the striatum. Synapse 61:943–950, 2007. © 2007 Wiley‐Liss, Inc.
Receiver‐oriented load‐balancing and reliable routing in wireless sensor networks
Authors: Chen Min , Leung Victor C. M. , Mao Shiwen , Kwon Taekyoung
Published: September 2007

Routing protocols in wireless sensor networks (WSNs) typically employ a transmitter‐oriented approach in which the next hop node is selected based on neighbor or network information. This approach incurs a large overhead when the accurate neighbor information is needed for efficient and reliable routing. In this paper, a novel receiver‐oriented load‐balancing and reliable routing (RLRR) protocol is proposed. In RLRR, an intermediate node solicits next hop candidates, each of which is to respond with its own backoff time dubbed a temporal gradient (TG). In this way, the next hop is selected without any central coordination on a packet‐by‐packet basis. Thus, each node needs not maintain any neighbor information. The remaining energy level used to determine the TG is always accurate and up‐to‐date. Furthermore, neighbor nodes whose hop count is less than the soliciting node participate in the next‐hop selection process with loop‐free operation guarantee. Comprehensive simulations are carried out to show that RLRR achieves relatively longer network lifetime and higher reliability than other existing schemes. Copyright © 2007 John Wiley & Sons, Ltd.
Determination of Oil Content and Fatty Acid Composition of Sesame Mutants Suited for Intensive Management Conditions
Authors: Arslan Çiğdem , Uzun Bülent , Ülger Salih , İlhan Çağırgan M.
Published: September 2007

Sesame mutants with closed capsules, determinate growth habit and wilt resistance, have been proposed to be suitable for intensive management conditions facilitating mechanized harvesting. The objective of our experiment was to determine the oil content and fatty acid composition of these mutants before they are placed on the market. Oil content and fatty acids were studied in 19 mutants, 6 breeding lines and 4 control source genotypes. The oil contents of the seeds ranged from 46.4 to 62.7%. The mutants had generally a lower oil content than the control genotypes except the wilting tolerant group. For unsaturated fatty acids, oleic acid was higher in the mutants and breeding lines while linoleic acid was lower in the seed oil. However, no mutants or breeding lines were found with radically different composition or with any undesirable lipid component. The closed capsule and determinate growth habit mutants need to be improved for oil content while their fatty acid composition is fine.
Nonlinear Schrödinger equation with a point defect
Authors: Fukuizumi Reika , Ohta Masahito , Ozawa Tohru
Published: September 2007

We study the nonlinear Schrödinger equation with a delta-function impurity in one space dimension. Local well-posedness is verified for the Cauchy problem in

H^{1}(\mathbb{R})

. In case of attractive delta-function, orbital stability and instability of the ground state is proved in

H^{1}(\mathbb{R})

.

On étudie l'équation de Schrödinger non linéaire avec une impureté delta de Dirac en dimension 1. On vérifie que le problème de Cauchy est localement bien posé dans

H^{1}(\mathbb{R})

. Dans le cas de delta de Dirac attractif, la stabilité et l'instabilité orbitale des ondes stationnaires sont vérifiées dans

H^{1}(\mathbb{R})

.
An integral equation in conformal geometry
Authors: Hang Fengbo , Wang Xiaodong , Yan Xiaodong
Published: September 2007

Motivated by Carleman's proof of the isoperimetric inequality in the plane, we study the problem of finding a metric with zero scalar curvature maximizing the isoperimetric ratio among all zero scalar curvature metrics in a fixed conformal class on a compact manifold with boundary. We derive a criterion for the existence and make a related conjecture.
On the Dirac delta as initial condition for nonlinear Schrödinger equations
Authors: Banica V. , Vega L.
Published: September 2007

In this article we will study the initial value problem for some Schrödinger equations with Dirac-like initial data and therefore with infinite

L^{2}

mass, obtaining positive results for subcritical nonlinearities. In the critical case and in one dimension we prove that after some renormalization the corresponding solution has finite energy. This allows us to conclude a stability result in the defocusing setting. These problems are related to the existence of a singular dynamics for Schrödinger maps through the so-called Hasimoto transformation.

Dans cet article on étudie le problème de Cauchy pour des équations de Schrödinger avec donnée initiale de type Dirac et donc avec masse

L^{2}

infinie, obtenant des résultats positifs pour les non linéarités sous-critiques. Dans le cas critique et en dimension un, on montre qu'après une certaine renormalisation la solution correspondante est d'énergie finie. On en déduit un résultat de stabilité dans le cas défocalisant. Ces problèmes sont liés à l'existence d'une dynamique singulière des applications de type Schrödinger par la transformation de Hasimoto.
Subcellular distribution of spermidine/spermine N1‐acetyltransferase
Authors: Holst C. Martina , Nevsten Pernilla , Johansson Fredrik , Carlemalm Eric , Oredsson Stina M.
Published: September 2007

The subcellular distribution of the polyamine catabolic enzyme spermidine/spermine N1‐acetyltransferase (SSAT) was studied in L56Br‐C1 cells treated with 10 μM N1,N11‐diethylnorspermine (DENSPM) for 24 h. Cells were fractioned into three subcellular fractions. A particulate fraction containing the mitochondria was denoted as the mitochondrial fraction. After DENSPM treatment, an increase in SSAT activity was mainly found in the mitochondrial fraction. Western blot analysis showed an increased level of the SSAT protein in the mitochondrial fraction compared to the cytosolic fraction. Immunofluorescence microscopy and immunogold labeling transmission electron microscopy also showed a mitochondrial association of SSAT. Transmission electron microscopy revealed that the endoplasmic reticulum was devoid of ribosomes in DENSPM‐treated cells, in contrast to control cells that contained ample ribosomes. An increased SSAT activity in connection with the mitochondria may be part of the mechanism of DENSPM‐induced apoptosis.
Rhabdastrellic acid‐A inhibited PI3K/Akt pathway and induced apoptosis in human leukemia HL‐60 cells
Authors: Guo Jing‐Feng , Zhou Jun‐Min , Zhang Yong , Deng Rong , Liu Jian‐nan , Feng Gong‐Kan , Liu Zong‐Chao , Xiao Ding‐Jun , Deng Song‐Zhi , Zhu Xiao‐Feng
Published: September 2007

Increasing evidence suggests that aberrant activation of PI3K/Akt is involved in many human cancers, and that inhibition of the PI3K/Akt pathway might be a promising strategy for cancer treatment. Our investigation indicates that Rhabdastrellic acid‐A, an isomalabaricane triterpenoid isolated from the sponge, Rhabdastrella globostellata, inhibits proliferation of HL‐60 cells with an IC50 value of 0.68 μg/ml, and induces apoptosis. Rhabdastrellic acid‐A also induces cleavage of the death substrate poly (ADP‐ribose) polymerase (PARP) and caspase‐3. Pretreatment of HL‐60 cells with the caspase‐3 specific inhibitor, DEVD‐CHO, prevents Rhabdastrellic acid‐A‐induced DNA fragmentation and PARP cleavage. Activated PI3K and Akt significantly decreases after treatment with Rhabdastrellic acid‐A in HL‐60 cells. Expression levels of protein bcl‐2, bax remain unchanged in response to Rhabdastrellic acid‐A treatment in HL‐60 cells. These results suggest that Rhabdastrellic acid‐A inhibits PI3K/Akt pathway and induces caspase‐3 dependent‐apoptosis in HL‐60 human leukemia cells.
mTOR is the rapamycin‐sensitive kinase that confers mechanically‐induced phosphorylation of the hydrophobic motif site Thr(389) in p70S6k
Authors: Hornberger Troy Alan , Sukhija Kunal Balu , Wang Xiao-Rong , Chien Shu
Published: September 2007

Mechanical stretch induces phosphorylation of the hydrophobic motif site Thr(389) in p70S6k through a rapamycin‐sensitive (RS) pathway that involves a unique PI3K‐independent mechanism. Rapamycin is considered to be a highly specific inhibitor of the protein kinase mTOR; however, mTOR is also considered to be a PI3K‐dependent signaling molecule. Thus, questions remain as to whether mTOR is the RS element that confers mechanically‐induced signaling to p70S6k(389). In this study, rapamycin‐resistant mutants of mTOR along with mechanical stretch were used to address this question. The results indicate that mTOR is the RS element and reveal that mTOR signaling can be activated through a PI3K‐independent mechanism.
SAMMA, a mandelic acid condensation polymer, inhibits dendritic cell‐mediated HIV transmission
Authors: Chang Theresa L. , Teleshova Natalia , Rapista Aprille , Paluch Maciej , Anderson Robert A. , Waller Donald P. , Zaneveld Lourens J.D. , Granelli-Piperno Angela , Klotman Mary E.
Published: September 2007

SAMMA, a mandelic acid condensation polymer, exhibits a broad antimicrobial activity against several sexually transmitted pathogens including human immunodeficiency virus (HIV). Here we demonstrated that SAMMA suppressed HIV transmission by dendritic cells (DCs), one of the first target cells for primary infection. The greatest inhibitory effect was achieved when SAMMA was present during the co‐culture with target cells. The inhibitory effect of SAMMA on DC‐mediated HIV transmission was not due to cytotoxicity. Analysis of the level of DC‐associated HIV p24 antigen revealed that SAMMA prevented HIV internalization by DCs when the virus was pre‐incubated with the compound. In contrast, pre‐incubation of DCs with SAMMA followed by wash‐off did not affect the amount of cell‐associated HIV p24 antigen. In addition, SAMMA blocked HIV glycoprotein‐mediated cell–cell fusion. This study suggests that SAMMA prevents HIV infection through multiple mechanisms.
α‐Tocopheryl succinate inhibits angiogenesis by disrupting paracrine FGF2 signalling
Authors: Neuzil Jiri , Swettenham Emma , Wang Xiu-Fang , Dong Lan-Feng , Stapelberg Michael
Published: September 2007

Malignant mesothelioma (MM) cells enhanced proliferation of endothelial cells (ECs) as well as their angiogenesis in vitro by secretion of fibroblast growth factor‐2 (FGF2). This effect was suppressed by pre‐treating MM cells with α‐tocopheryl succinate (α‐TOS), which inhibited FGF2 secretion by inducing mitochondria‐dependent generation of reactive oxygen species. The role of FGF2 was confirmed by its down‐regulation by treating MM cells with siRNA, abolishing EC proliferation and wound healing enhancement afforded by MM cells. We conclude that α‐TOS disrupts angiogenesis mediated by MM cells by inhibiting FGF2 paracrine signalling.
The sterol transporting heterodimer ABCG5/ABCG8 requires bile salts to mediate cholesterol efflux
Authors: Vrins Carlos , Vink Edwin , Vandenberghe Kristin E. , Frijters Raoul , Seppen Jurgen , Groen Albert K.
Published: September 2007

The ATP binding cassette transporters ABCG5 and ABCG8 are indispensable for hepatobiliary cholesterol transport. In this study, we investigated the specificity of the heterodimer for cholesterol acceptors. Dog gallbladder epithelial cells were mono‐ or double‐transfected with lentiviral mouse Abcg5 and Abcg8 vectors. Double‐transfected cells showed increased efflux to different bile salt (BS) species, while mono‐transfected cells did not show enhanced efflux. The efflux was initiated at micellar concentrations and addition of phosphatidylcholine increased efflux. Cholesterol secretion was highly BS dependent, whereas other cholesterol acceptors such as ApoAI, HDL or methyl‐β‐cyclodextrin did not elicit Abcg5/g8 dependent cholesterol secretion.