bluuebunny/crossref_metadata_2025 huggingface dataset:
Bacteroides fragilisenterotoxin induces cyclooxygenase‐2 and fluid secretion in intestinal epithelial cells through NF‐κB activation
Authors: Kim Jung Mogg , Lee Jin Young , Yoon Young Mee , Oh Yu‐Kyoung , Kang Ju Seop , Kim Yeong‐Jeon , Kim Kyoung‐Ho
Published: August 2006

Bacteroides fragilisproduces an approximately 20‐kDa heat‐labile toxin (B. fragilisenterotoxin, BFT) which is known to be associated with diarrhea. To determine whether cyclooxygenase (COX)‐2,viaNF‐κB activation, can contribute to BFT‐induced diarrhea, the relationship between COX‐2 expression and fluid secretion in BFT‐stimulated human intestinal epithelial cells was examined. BFT stimulation increased the expression of COX‐2, but not COX‐1, in human intestinal epithelial cells. Suppression of the NF‐κB signal significantly decreased COX‐2 expression in response to BFT stimulation. Prostaglandin E2(PGE2) levels were increased in parallel with COX‐2 expression, and, conversely, PGE2production was significantly inhibited when COX‐2 or NF‐κB activities were suppressed using COX‐2 small interfering RNA (siRNA), p65 NF‐κB subunit siRNA, or a retrovirus encoding the IκBα superrepressor. In addition, a selective COX‐2 inhibitor, NS‐398, significantly inhibited the increased cAMP level induced by BFT stimulation. Furthermore, a selective COX‐2 inhibitor prevented BFT‐induced PGE2production and ileal fluid secretion in a mouse ileal loop model. These results suggest that the secretory response to BFT stimulation may be mediated by the production of PGE2, through NF‐κB activation and the up‐regulation of COX‐2 in intestinal epithelial cells.
Chiral Half‐Sandwich Ruthenium(II) Complexes as Catalysts in 1,3‐Dipolar Cycloaddition Reactions of Nitrones with Methacrolein (Eur. J. Inorg. Chem. 16/2006)
Authors: Carmona Daniel , Lamata M. Pilar , Viguri Fernando , Ferrer Joaquina , García Néstor , Lahoz Fernando J. , Martín M. Luisa , Oro Luis A.
Published: August 2006

The cover picture shows the structure of a chiral half‐sandwich ruthenium(II) complex with the (4S)‐2‐[2‐(diphenylphosphanyl)phenyl]‐4‐isopropyl‐1,3‐oxazoline ligand that catalyzes the asymmetric 1,3‐dipolar cycloaddition reaction of nitrones with methacrolein. Catalyst precursors as well as dipolarophile or nitrone‐containing intermediates have been isolated and spectroscopically and/or crystallographically characterized. Details are discussed in the article by D. Carmona, M. P. Lamata, L. A. Oro et al. on p. 3155 ff.
Distinct patterns of DNA copy number alteration are associated with different clinicopathological features and gene‐expression subtypes of breast cancer
Authors: Bergamaschi Anna , Kim Young H. , Wang Pei , Sørlie Therese , Hernandez‐Boussard Tina , Lonning Per E. , Tibshirani Robert , Børresen‐Dale Anne‐Lise , Pollack Jonathan R.
Published: August 2006

Breast cancer is a leading cause of cancer‐death among women, where the clinicopathological features of tumors are used to prognosticate and guide therapy. DNA copy number alterations (CNAs), which occur frequently in breast cancer and define key pathogenetic events, are also potentially useful prognostic or predictive factors. Here, we report a genome‐wide array‐based comparative genomic hybridization (array CGH) survey of CNAs in 89 breast tumors from a patient cohort with locally advanced disease. Statistical analysis links distinct cytoband loci harboring CNAs to specific clinicopathological parameters, including tumor grade, estrogen receptor status, presence of TP53 mutation, and overall survival. Notably, distinct spectra of CNAs also underlie the different subtypes of breast cancer recently defined by expression‐profiling, implying these subtypes develop along distinct genetic pathways. In addition, higher numbers of gains/losses are associated with the “basal‐like” tumor subtype, while high‐level DNA amplification is more frequent in “luminal‐B” subtype tumors, suggesting also that distinct mechanisms of genomic instability might underlie their pathogenesis. The identified CNAs may provide a basis for improved patient prognostication, as well as a starting point to define important genes to further our understanding of the pathobiology of breast cancer. This article contains Supplementary Material available at http://www.interscience.wiley.com/jpages/1045‐2257/suppmat. © 2006 Wiley‐Liss, Inc.
Hippocampal place cells: The “where” of episodic memory?
Authors: Kentros Clifford
Published: August 2006

Neuropsychologists have clearly implicated the hippocampus in the consolidation of memory, particularly episodic memory, the mental replay of past experiences. When recorded from behaving animals, by far the most obvious firing pattern of the primary neurons of the hippocampus is the place field: a cell tends to fire only when the animal's head is in a particular part of its environment. It seems reasonable to suspect that the primary firing correlate of the primary neurons of a structure should underlie the primary function of that structure as revealed by behavioral lesion experiments. However, we are currently still at a loss to explain how the firing of hippocampal neurons contributes to hippocampal function. This review seeks to examine the commonalities between place cells and episodic memory, and posits that an analogy can be made between the stabilization of place fields and the consolidation of memory. © 2006 Wiley‐Liss, Inc.
Stalactite drip rate variations controlled by air pressure changes: an example of non‐linear infiltration processes in the ‘Cueva del Agua’ (Spain)
Authors: Fernández‐Cortés A. , Calaforra J. M. , Sánchez‐Martos F. , Gisbert J.
Published: August 2006

A study of drip water from a stalactite in the Cueva del Agua (Granada, southern Spain) over four hydrological years has enabled a detailed characterization of infiltration through the non‐saturated zone of this cave. The most significant aspects are: (1) The drip water regime is not seasonal, but is linked instead to slow infiltration. Sudden changes in the drip water regime are detected, due to infiltration along the preferential flow paths and the draining of water of supersaturated water reserves from the microfissure and pore system. (2) The accumulation of excess rain in the unsaturated zone dislodges the reserve of supersaturated water from the matrix of microfissures and pores, giving rise to an average increase in drip intensity of 2·2 ± 0·5 mm h−1 and 37 ± 13 µS cm−1 in the electrical conductivity of the water. (3) Time‐series analysis of the drip water demonstrates a lack of linearity over time of the drip rate, indicating a chaotic regime. (4) When the dripping is constant, barometric oscillation of the air is the principal factor that causes the lack of linearity in the drip flow. In this way, over an average of 2–3 days, a mean variation of the air pressure inside the cave of 10 ± 3·7 mbar causes a mean oscillation in the drip rate of 0·5 ± 0·2 mm h−1. This increase in air pressure is translated as an increase in the relative thickness of the gaseous phase of the drip water at the cost of the aqueous phase, so reducing the drip intensity of the stalactite. Copyright © 2006 John Wiley & Sons, Ltd.
EPI image reconstruction with correction of distortion and signal losses
Authors: Liu Guoxiang , Ogawa Seiji
Published: August 2006

Purpose

To derive and implement a method for correcting geometric distortions and recovering magnetic resonance imaging (MRI) signal losses caused by susceptibility‐induced magnetic field gradients (SFGs) in regions with large static field inhomogeneities in echo‐planar imaging (EPI).

Materials and Methods

Factors to account for field inhomogeneities and SFGs were added in a traditional EPI equation that was a simple Fourier transform (FT) for expressing the actual k‐space data of an EPI scan. The inverse calculation of this “distorted EPI” equation was used as a kernel to correct geometric distortions and reductions in intensity during reconstruction. A step‐by‐step EPI reconstruction method was developed to prevent complicated phase unwrapping problems. Some EPI images of phantom and human brains were reconstructed from standard EPI k‐spaces.

Results

All images were reconstructed using the proposed multistep method. Geometric distortions were corrected and SFG‐induced MRI signal losses were recovered.

Conclusion

Results suggest that applying our method for reconstructing EPI images to reduce distortions and MRI signal losses is feasible. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Desert water harvesting from takyr surfaces: assessing the potential of traditional and experimental technologies in the Karakum
Authors: Fleskens L. , Ataev A. , Mamedov B. , Spaan W. P.
Published: August 2006

From historical times the traditionally nomadic people in desert environments of Turkmenistan have applied a range of innovative technologies to secure water supply for consumptive and productive purposes. These technologies make use of takyrs, flat or slightly sloping dense clay surfaces which act as natural catchment areas. In recent history, these technologies have been neglected, in part due to a booming water supply through irrigation development, and takyr surfaces have suffered various degradation processes. However, the limited scope for further extension of irrigation systems presents a challenge to reconsider these traditional technologies. In this paper, results of cost‐benefit analysis are presented by which an assessment is made of the potential of both traditional and experimental takyr use technologies. It is shown that they bear considerable potential for the future at relatively low investment cost, that they may help limit degradation processes and provide for a sustainable development pathway for the inhabitants of the desert. A main challenge in order to benefit from this potential is to find an appropriate management structure for maintenance and resource use of these water‐harvesting technologies. Copyright © 2006 John Wiley & Sons, Ltd.
Modifications of aminoglycoside antibiotics targeting RNA
Authors: Zhou Jian , Wang Guannan , Zhang Li‐He , Ye Xin‐Shan
Published: August 2006

The increased awareness of the central role of RNA has led to realization that RNA, as structural and functional information accumulation, is also drug target to small molecular therapy. Aminoglycosides are a group of well‐known antibiotics, which function through binding to specific sites in prokaryotic ribosomal RNA (rRNA) and affecting the fidelity of protein synthesis. Unfortunately, their clinical practice has been curtailed by toxicity and rapid increasing number of resistant strains. Therefore, it is highly desirable to design new modified aminoglycosides that will overcome the undesirable properties of natural occurring aminoglycosides. On the other hand, aminoglycosides as potential antiviral (HIV) agents were also reported. Herein, we survey the current efforts to develop new aminoglycoside derivatives with modification and reconstruction on each sugar ring and review the latest advances in structure‐activity relationships (SAR). © 2006 Wiley Periodicals, Inc. Med Res Rev, 27, No. 3, 279–316, 2007
Decreased protein tyrosine phosphorylation and membrane fluidity in spermatozoa from infertile men with varicocele
Authors: Buffone M.G. , Brugo‐Olmedo S. , Calamera J.C. , Verstraeten S.V. , Urrutia F. , Grippo L. , Corbetta J.P. , Doncel G.F.
Published: August 2006

Varicocele is a prevalent pathology among infertile men. The mechanisms linking this condition to infertility, however, are poorly understood. Our previous work showed a relationship between sperm functional quality and the ability of spermatozoa to respond to capacitating conditions with increased membrane fluidity and protein tyrosine phosphorylation. Given the reported association between varicocele, oxidative stress, and sperm dysfunction, we hypothesized that spermatozoa from infertile patients with varicocele might have a combined defect at the level of membrane fluidity and protein tyrosine phosphorylation. Semen samples from infertile patients with and without grade II/III left varicocele were evaluated for motion parameters (computer‐assisted semen analysis [CASA]), hyperactivation (CASA), incidence and intensity of protein tyrosine phosphorylation (phosphotyrosine immunofluorescence and western blotting), and membrane fluidity (Laurdan fluorometry), before and after a capacitating incubation (6 hr at 37°C in Ham's F10/BSA, 5% CO2). Spermatozoa from varicocele samples presented a decreased response to the capacitating challenge, showing significantly lower motility, hyperactivation, incidence and intensity of tyrosine phosphorylation, and membrane fluidity. The findings reported in this article indicate that the sperm dysfunction associated to infertile varicocele coexists with decreased sperm plasma membrane fluidity and tyrosine phosphorylation. These deficiencies represent potential new pathophysiological mechanisms underlying varicocele‐related infertility. Mol. Reprod. Dev. 73: 1591–1599, 2006. © 2006 Wiley‐Liss, Inc.
In vivo cellular imaging of lymphocyte trafficking by MRI: A tumor model approach to cell‐based anticancer therapy
Authors: Smirnov Pierre , Lavergne Elise , Gazeau Florence , Lewin Maïté , Boissonnas Alexandre , Doan Bich‐Thuy , Gillet Brigitte , Combadière Christophe , Combadière Béhazine , Clément Olivier
Published: August 2006

The aim of this study was to demonstrate the feasibility of in vivo cell tracking to monitor anticancer cell therapy by means of a high‐resolution noninvasive MRI method. Ovalbumin‐specific splenocytes (OT‐1) labeled with anionic γ‐Fe2O3 superparamagnetic iron oxide (SPIO) nanoparticles were adoptively transferred into C57BL/6 mice with growing ovalbumin‐expressing tumors. OT‐1 cells were tracked in vivo by 7 T MRI 24, 48, and 72 hr after they were injected. The results showed significant negative enhancement of the spleen at 24 hr, and of the tumor at 48 and 72 hr, after labeled cell injection. This suggests that the lymphocytes initially homed toward the spleen and were then recruited by the tumor. The presence of labeled cells was confirmed in ex vivo by 9.4 T microimaging of tumors and magnetic sorting of spleen cells. These results confirm that MR tracking of lymphocytes is feasible in vivo. This high‐resolution imaging method could be used to improve the monitoring of immune cell therapy. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
x‐f choice: Reconstruction of undersampled dynamic MRI by data‐driven alias rejection applied to contrast‐enhanced angiography
Authors: Malik Shaihan J. , Schmitz Stephan , O'Regan Declan , Larkman David J. , Hajnal Joseph V.
Published: August 2006

A technique for reconstructing dynamic undersampled MRI data, termed “x‐f choice,” was developed and applied to dynamic contrast‐enhanced MR angiography (DCE‐MRA). Regular undersampling in k‐t space (a hybrid of k‐space and time) creates aliasing in the conjugate x‐f space that must be resolved. When regions in the object containing fast dynamic change are sparse, as in DCE‐MRA, signal overlap caused by aliasing is often much less than the undersample factor would imply. x‐f Choice reconstruction identifies overlapping signals using a model of the full non‐aliased x‐f space that is automatically generated from the undersampled data, and applies parallel imaging (PI) to separate them. No extra reference scans are required to generate either the model or the coil sensitivity maps. At each location in the reconstructed images, g‐factor noise amplification is compared with predicted reconstruction errors to obtain an optimized solution. Acceleration factors greater than the number of receiver coils are possible, but are limited by the sparseness of the dynamic content and the signal‐to‐noise ratio (SNR) (in DCE‐MRA the latter is dominant). Temporal fidelity was validated for up to a factor 10 speed‐up using retrospectively undersampled data from a six‐coil array. The method was tested on volunteers using fivefold prospective undersampling. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Transrectal ultrasound‐guided biopsy of prostate voxels identified as suspicious of malignancy on three‐dimensional 1H MR spectroscopic imaging in patients with abnormal digital rectal examination or raised prostate specific antigen level of 4–10 ng/ml
Authors: Kumar Virendra , Jagannathan N.R. , Kumar Rajeev , Thulkar Sanjay , Gupta S. Dutta , Hemal A.K. , Gupta N.P.
Published: August 2006

Results of the evaluation of transrectal ultrasound (TRUS) guided needle biopsy of voxels identified as suspicious of malignancy on magnetic resonance spectroscopic imaging (MRSI) in a large cohort of men (n = 83) with abnormal digital rectal examination (DRE) [prostate specific antigen (PSA) 0–4 ng/ml] or PSA less than 10 ng/ml, are reported. Three‐dimensional 1H MRSI was carried out at 1.5 T using a pelvic‐phased array coil in combination with an endorectal surface coil. Voxels were classified as suspicious of malignancy based on Cit/(Cho + Cr) metabolite ratio. TRUS‐guided biopsy of suspicious voxels was performed using the z‐ and x‐coordinates obtained from MR images and two to three cores were taken from the suspected site. A systematic sextant biopsy was also carried out. MRSI showed voxels suspicious of malignancy in 44 patients while biopsy revealed cancer in 11 patients (25%). Patients who were negative for malignancy on MRSI were also negative on biopsy. An overall sensitivity of 100%, specificity of 54%, negative predictive value of 100% and accuracy of 60% were obtained. The site of biopsy was confirmed (n = 20) as a hypo‐intense area on repeat MRI while repeat MRSI revealed high choline and low citrate. The overall success rate of MRI‐directed TRUS‐guided biopsy of 25% was higher compared with a 9% success rate achieved without MR guidance in another group of 120 patients. Our results indicate that TRUS‐guided biopsy of suspicious area identified as malignant from MRSI can be performed using the coordinates of the voxel derived from MR images. This increases the detection rate of prostate cancer in men with PSA level <10 ng/ml or abnormal DRE and also demonstrates the potential of MR in routine clinical practice. Copyright © 2006 John Wiley & Sons, Ltd.
Synthesis and properties of new aromatic poly(ester‐imide)s derived from 4‐p‐biphenyl‐2,6‐bis(4‐trimellitimidophenyl) pyridine and various dihydroxy compounds
Authors: Behniafar Hossein , Khaje Mirzai Ali Akbar , Saeed Ali Beit
Published: August 2006

A novel class of wholly aromatic poly(ester‐imide)s, having a biphenylene pendant group, with inherent viscosities of 0.32–0.49 dL g−1 was prepared by the diphenylchlorophosphate‐activated direct polyesterification of the preformed imide‐ring‐containing diacid, 4‐p‐biphenyl‐2,6‐bis(4‐trimellitimidophenyl)pyridine (1) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. A reference diacid, 2,6‐bis(trimellitimido)pyridine (2) without a biphenylene pendant group and two phenylene rings in the backbone, was also synthesized for comparison purposes. At first, with due attention to structural similarity and to compare the characterization data, a model compound (3) was synthesized by the reaction of compound 1 with two mole equivalents of phenol. Moreover, the optimum condition of polymerization reactions was obtained via a study of the model compound synthesis. All of the resulting polymers were characterized by Fourier transform infrared and 1H NMR spectroscopy and elemental analysis. The ultraviolet λmax values of the poly(ester‐imide)s were also determined. All of the resulting polymers exhibited excellent solubility in common organic solvents, such as pyridine, chloroform, tetrahydrofuran, and m‐cresol, as well as in polar organic solvents, such as N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, N,N‐dimethylformamide, and dimethyl sulfoxide. The crystalline nature of the polymers obtained was evaluated by means of wide‐angle X‐ray diffraction. The resulting poly(ester‐imide)s showed nearly an amorphous nature, except poly(ester‐imide) derived from 4,4′‐dihydroxy biphenyl. The glass transition temperatures (Tg) of the polymers determined by differential scanning calorimetry thermograms were in the range 298–342 °C. The 10% weight loss temperatures (T10%) from thermogravimetric analysis curves were found to be in the range 433–471 °C in nitrogen. Films of the polymers were also prepared by casting the solutions. Copyright © 2006 Society of Chemical Industry
Crystal structure of GlcAT‐S, a human glucuronyltransferase, involved in the biosynthesis of the HNK‐1 carbohydrate epitope
Authors: Shiba Tomoo , Kakuda Shinako , Ishiguro Masaji , Morita Ippei , Oka Shogo , Kawasaki Toshisuke , Wakatsuki Soichi , Kato Ryuichi
Published: August 2006

The HNK‐1 carbohydrate epitope is found in various neural cell adhesion molecules. Two glucuronyltransferases (GlcAT‐P and GlcAT‐S) are involved in the biosynthesis of HNK‐1 carbohydrate. Our previous study on the crystal structure of GlcAT‐P revealed the reaction and substrate recognition mechanisms of this enzyme. Comparative analyses of the enzymatic activities of GlcAT‐S and GlcAT‐P showed that there are notable differences in the acceptor substrate specificities of these enzymes. To elucidate differences between their specificities, we now solved the crystal structure of GlcAT‐S. Residues interacting with UDP molecule, which is a part of the donor substrate, are highly conserved between GlcAT‐P and GlcAT‐S. On the other hand, there are some differences between these proteins in the manner they recognize their respective acceptor substrates. Phe245, one of the most important GlcAT‐P residues for the recognition of acceptors, is a tryptophan in GlcAT‐S. In addition, Val320, which is located on the C‐terminal long loop of the neighboring molecule in the dimer and critical in the recognition of the acceptor sugar molecule by the GlcAT‐P dimer, is an alanine in GlcAT‐S. These differences play key roles in establishing the distinct specificity for the acceptor substrate by GlcAT‐S, which is further supported by site‐directed mutagenesis of GlcAT‐S and a computer‐aided model building of GlcAT‐S/substrate complexes. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Structure and magnetic properties of metastable Co–Cu solid solution nanowire arrays fabricated by electrodeposition
Authors: Wang Tao , Li Fashen , Wang Ying , Song Lijing
Published: August 2006

Nanowire arrays of the metastable Cox Cu1–x (0.20 ≤ x ≤ 0.85) solid solution system which can not be obtained by equilibrium methods, were prepared by electrodeposition in pores of anodic aluminum oxide (AAO) template, and subsequently annealed at different temperatures. The as‐deposited samples all show single phase of fcc structure, and lattice parameters decrease with the increase of Co content and fundamentally accord with Vegard's law. The phase transition with heat treatment was investigated by X‐ray diffraction and differential thermal analysis (DTA) which further confirmed the formation of solid solution. With Co content increasing, the coercivity along nanowire axis for as‐deposited samples increases, but it decreases for the annealed samples at 700 °C. This phenomenon was explained considering the interaction of Co particles through Cu in nanowires after phase separation. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical characterization of polyethylene and cobalt phthalocyanine ultrathin films by means of the ATR technique at surface plasmon resonance
Authors: Rodríguez Juárez M. , Muñoz Aguirre N. , Martínez Pérez L. , Garibay‐Febles V. , Lozada‐Cassou M. , Becerril M. , Angel O. Zelaya
Published: August 2006

It is well known that the development and determination of optical properties of ultrathin films is an important issue in many technological areas. In this work organic polyethylene (PE) and cobalt phthalocyanines (CoPc) ultrathin films were deposited over metal films using the r.f. sputtering and thermal evaporation techniques, respectively. Attenuated total reflection (ATR) measurements for the system organic film/metal at the surface plasmon resonance (SPR) were used for determining the thicknesses and optical properties of the PE and CoPc thin films. Thicknesses of the order of some nanometers were found, fitting the theoretical multilayer ATR model, for p polarization monochromatic light, to the experimental reflection data. The dielectric function of CoPc ultrathin films was determined at a wavelength of 632.8 nm. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic characteristics of Mn–Co–Ti substituted barium ferrite synthesized by sol–gel processing
Authors: Ghasemi A. , Saatchi A. , Salehi M. , Hossienpour A. , Morisako A. , Liu X.
Published: August 2006

BaFe12–x (Mn0.5Co0.5Ti)x /2O19 hexaferrites with x = 1, 2 and 3 were prepared by a sol–gel process. The reaction temperature was much lower than that of the conventional ceramic method. The ferrite powders possess a hexagonal shape and are well separated from one another. Thermogravimetric analysis, X‐ray diffraction, a scanning electron microscope, an ac susceptometer and a vibrating sample magnetometer were used to analyze their structures and magnetic properties. The results showed that for all the samples magnetoplumbite structures have been formed. The samples with x = 2 and 3 have higher magnetic susceptibility and larger coercive force. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Rapid crystallization of WS2 films assisted by a thin nickel layer: An in situ energy‐dispersive X‐ray diffraction study
Authors: Ellmer K. , Seeger S. , Mientus R.
Published: August 2006

By rapid thermal crystallization of an amorphous WS3+x film, deposited by reactive magnetron sputtering at temperatures below 150 °C, layer‐type semiconducting tungsten disulfide films (WS2) were grown. The rapid crystallization was monitored in real‐time by in situ energy‐dispersive X‐ray diffraction. The films crystallize very fast (>40 nm/s), provided that a thin nickel film acts as nucleation seeds. Experiments on different substrates and the onset of the crystallization only at a temperature between 600 and 700 °C points to the decisive role of seeds for the textured growth of WS2, most probably liquid NiSx drops. The rapidly crystallized WS2 films exhibit a pronounced (001) texture with the van der Waals planes oriented parallel to the surface, leading to photoactive layers with a high hole mobility of about 80 cm2/Vs making such films suitable as absorbers for thin film solar cells. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hot phonons in GaN channels for HEMTs
Authors: Matulionis A.
Published: August 2006

Accumulation of non‐equilibrium longitudinal optical (LO) phonons (termed hot phonons) is considered as a possible cause for limitation of hot‐electron drift velocity at high electric fields in a GaN biased channel with a two‐dimensional electron gas (2DEG). Equivalent hot‐phonon temperature and hot‐phonon lifetime are estimated from experimental results on hot‐electron noise at a microwave frequency. Dependence of the hot‐phonon parameters on electron density and channel composition is investigated, and frequency performance of high‐electron‐mobility transistors (HEMTs) is discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Solid‐Phase Synthesis of Aryl‐Alkylamine Derivatives Using Protected Aminoalcohol Building Blocks on SynPhaseTM Lanterns
Authors: Zajdel Pawel , Subra Gilles , Pawłowski Maciej , Martinez Jean
Published: August 2006

A series of aryl‐alkylamine carboxamide and sulfonamide derivatives were synthesized on a BAL linker using SynPhaseTM Lanterns. All the reaction steps were performed on a solid support. The key stage was on‐resin substitution of TBDPSi‐protected aminoalcohols with various amines, which circumvented the multistep solution‐phase synthesis of alkylamine building blocks. The chemistry applied allows building up focused libraries targeted on CNS receptors.
Synthesis of Fluorous‐FMOC Reagents and Purification of Protected Dipeptides with Fluorous Solid Phase Extraction
Authors: Matsugi Masato , Yamanaka Kunihiro , Inomata Issei , Takekoshi Nao , Hasegawa Masakazu , Curran Dennis P.
Published: August 2006

Fluorous‐FMOC (f‐FMOC) reagents bearing C4F9 or C6F13 chains were prepared and the f‐FMOC protection for amino acid was conducted. Following peptide coupling, the resulting fluorous dipeptides were separated from the non‐fluorous by‐products effectively by using fluorous solid phase extraction.
Analysis of self‐interaction correction for describing core excited states
Authors: Imamura Yutaka , Nakai Hiromi
Published: August 2006

Core‐excitation energies are calculated by the self‐interaction‐corrected time‐dependent density functional theory (SIC‐TDDFT) and SIC‐delta‐self‐consistent field (SIC‐ΔSCF) methods. For carbon monoxide, SIC‐TDDFT severely overestimates core‐excitation energies, while the SIC‐ΔSCF method using Kohn–Sham density functional theory (KS‐DFT) slightly overestimates. These behaviors are attributed to the fact that the self‐interaction errors in the total and orbital energies considerably differ. We evaluate the difference of the self‐interaction errors for the Slater exchange functional. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Singlet excitation energies of thiophene derivatives of fluorene: TD‐DFT study
Authors: Gong Zhijun , Lagowski Jolanta B.
Published: August 2006

Fluorene‐thiophene (FT)‐based oligomers and polymers and their derivatives are good candidates for organic blue light‐emitting diodes. In this work, the intrinsic properties of the ground and excited states of FT monomer and its derivatives are studied. The ground‐state optimized structures and energies are obtained using molecular orbital theory and density functional theory (DFT). The ground‐state potential energy curves or surfaces of FT and its derivatives are also obtained. All derivatives are nonplanar in their electronic ground states. The character and energy of the first 20 singlet–singlet electronic transitions are investigated by applying the time‐dependent density functional theory (TD‐DFT) approximations to the correspondingly optimized ground‐state geometries. The lowest singlet state is studied with the configuration interaction (singles) approach (CIS). Excitation energies are red shifted when the FT unit or its derivatives are extended longitudinally. CIS results suggest geometry relaxation in the first singlet excited state. When available, a comparison is made with experimental results. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Large wood addition for aquatic habitat rehabilitation in an incised, sand‐bed stream, Little Topashaw Creek, Mississippi
Authors: Shields F. Douglas , Knight Scott S. , Stofleth John M.
Published: August 2006

Large wood (LW) is a key component of stream habitats, and degraded streams often contain little wood relative to less‐impacted ones. Habitat rehabilitation and erosion control techniques that emphasize addition of natural wood in the form of individual elements or structures are increasingly popular. However, the efficacy of wood addition, especially in physically unstable, warmwater systems is not well established. The effects of habitat rehabilitation of Little Topashaw Creek, a sinuous, sand‐bed stream draining 37 km2 in northwest Mississippi are described herein. The rehabilitation project consisted of placing 72 LW structures along eroding concave banks of a 2‐km reach and planting 4000 willow cuttings in sandbars opposite or adjacent to the LW structures. Response was measured by monitoring flow, channel geometry, physical aquatic habitat and fish populations in treated and untreated reaches for 2 years before and 4 years after rehabilitation. Initially, LW structures reduced high flow velocities at concave bank toes. Progressive failure of the LW structures and renewed erosion began during the second year after rehabilitation, with only 64% of the structures and about 10% of the willow plantings surviving for 3 years. Accordingly, long‐term changes in physical habitat attributable to rehabilitation were limited to an increase in LW density. Fish biomass increased in the treated reach, and species richness approximately doubled in all reaches after rehabilitation, suggesting the occurrence of some sort of stressful event prior to our study. Fish community composition shifted toward one typical of a lightly degraded reference site, but similar shifts occurred in the untreated reaches downstream, which had relatively high levels of naturally occurring LW. Large wood is a key component of sand‐bed stream ecosystems, but LW addition for rehabilitation should be limited to sites with more stable beds and conditions that foster rapid woody plant colonization of sediment deposits. Published in 2006 by John Wiley & Sons, Ltd.
Response of the benthic macroinvertebrate community in a northern Michigan stream to reduced summer streamflows
Authors: Wills Todd C. , Baker Edward A. , Nuhfer Andrew J. , Zorn Troy G.
Published: August 2006

We evaluated the response of benthic macroinvertebrates in a Michigan trout stream to flow reduction by diverting water from a 602 m reach of Hunt Creek from June through August of 1994, 1997 and 1998. We also assessed the utility of the Physical Habitat Simulation system (PHABSIM) in predicting the response of benthic insects to water withdrawals by testing the assumption of a positive linear relationship between modelled habitat (weighted usable area, WUA) and the density of 13 benthic insect families. Our findings showed that the density of filter feeding and grazing insect taxa, as well as insects classified as obligate erosional zone taxa, declined significantly in the dewatered (treatment) zone (TZ) when 90% of flow was diverted. Density of Ephemeroptera, Plecoptera and Trichoptera (EPT) taxa in the TZ was significantly lower when 90% of water was diverted as compared to density at baseflow or when flow was reduced by 50%. The density of all insects in an upstream reference zone riffle (RZ), where flow was not altered, did not change among experimental periods. Although overall reductions in the density of benthic insects at 90% flow reduction coincided with lower PHABSIM predictions of WUA, we found poor linear correlation between WUA at different flows and the density of the 13 benthic insect families for which WUA was modelled. The low proportion of variation explained by WUA for all families modelled suggests that WUA alone is not an accurate predictor of benthic insect density. Resource managers should consider the potential consequences of water withdrawals to all components of stream communities, including benthic macroinvertebrates. However, caution should be applied when using the PHABSIM technique in groundwater‐fed streams such as Hunt Creek, because most relationships between WUA and benthic insect density were insignificant. Copyright © 2006 John Wiley & Sons, Ltd.
Changing times and strategies: Shell's contribution to sustainable community development in the Niger Delta, Nigeria
Authors: Ite Uwem E.
Published: August 2006

Sustainable development and poverty are pervasive problems in the Niger Delta, mainly due to lack of significant Nigerian government commitment to the development of the region. As a corporate citizen, Shell has contributed in various ways to local community development in the area. Based on a critical analysis of the changes in its strategies and policies, the paper contends that Shell's previous approaches to community development in the Niger Delta encouraged unsustainable development and a culture of dependency. It concludes that the recently launched sustainable community development strategy has the potential to succeed where others failed, if it is implemented within a tri‐sector partnership framework involving Shell, the Nigerian government and civil society. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment.
Neonatal caffeine administration causes a permanent increase in the dendritic length of prefrontal cortical neurons of rats
Authors: Juárez‐méndez Sergio , Carretero Rosalba , Martínez‐Tellez Rubelia , Silva‐gómez Adriana B. , Flores Gonzalo
Published: August 2006

We studied the morphological changes of the dendritic length of the pyramidal neurons of the prefrontal cortex (PFC) induced by the effect of chronic administration of caffeine in the neonatal rat. The caffeine (50 mg/kg, s.c.) was injected from day 1 after birth (P1) to day 12 (P12). The morphology of the pyramidal neurons of layer 3 of the PFC was investigated in these animals at two different ages, before puberty (P35) and after puberty (P70). Before the animals were sacrificed by using overdoses of sodium pentobarbital and being perfused intracardially with 0.9% saline, the locomotor activity in a novel environment was measured. The brains were then removed, processed by the Golgi‐Cox stain, and analyzed by the Sholl method. The dendritic morphology clearly showed that the neonatal animals administered caffeine showed an increase in the dendritic length of the pyramidal neurons of the PFC when compared with the control animals at both ages. The present results suggest that neonatal administration of caffeine may in part affect the dendritic morphology of the pyramidal cells of this limbic structure and this effect persists after puberty and may be implicated in several brain processes. Synapse 60:450–455, 2006. © 2006 Wiley‐Liss, Inc.
LAT1 gene variants—potential factors influencing the clinical course of phenylketonuria
Authors: Bik‐Multanowski Miroslaw , Pietrzyk Jacek J.
Published: August 2006

The LAT1 amino acid exchanger is responsible for phenylalanine transport across the blood–brain barrier. As phenylalanine excess in the brain leads to mental retardation in untreated patients with phenylketonuria, mutations of the LAT1 gene can be responsible for milder clinical manifestations (lower brain toxicity of hyperphenylalaninaemia) observed in some patients. The aim of this study was to screen for LAT1 gene mutations in phenylketonuric patients. Within the coding sequence of the gene, three polymorphism and one new mutation (G41D) were detected. The protein sequence change due to the mutation described could influence the clinical course of phenylketonuria.
Archeological benchmarking: Fred Harvey and the service profit chain, Circa 1876
Authors: Brown Karen A. , Hyer Nancy Lea
Published: August 2006

This article illustrates the potential for studying best practices from the past, engaging in what we term archeological benchmarking. Our focus for this study was the Fred Harvey Company, which operated a highly successful string of restaurants and hotels along the Atchison, Topeka and Santa Fe Railroad line starting in 1876, reaching its peak around 1912, and continuing until the early 1950s. Fred Harvey was a visionary businessman who understood many of the key concepts guiding the most successful service operations today. This article describes the operating system Harvey used for delivering 15 million meals per year in 65 restaurants extending over a span reaching from Chicago to San Francisco. The underpinnings of Harvey's system foretold concepts considered new today, particularly the service profit chain [Heskett, J., Jones, T., Loveman, G., Sasser Jr., W.E., Schlesinger, L., 1994] and its reliance on a clear operations strategy supported by well‐trained, loyal employees and a congruent system of measurement. It is significant that Harvey achieved his success without the advantages of modern information systems by relying, instead, on his iconic leadership, dogged attention to mundane details, and the service culture he was able to embed throughout the far‐flung enterprise. The Harvey story is an example of ahead‐of‐its‐time operations thinking, but it also asks us to attend more broadly to the history of the field – as does this entire special issue – as a source of inspiration and grounding.
Fate of unproductive and unattractive habitats: recent changes in Iberian steppes and their effects on endangered avifauna
Authors: LAIOLO PAOLA , TELLA JOSÉ L.
Published: August 2006

Steppe ecosystems worldwide are affected by agricultural development and generally unprotected. Spanish shrub-steppes contain endangered avifauna, and this paper analyses their state of habitat conservation, the changes that have occurred in the last decade, primary productivity and its relationship with land exploitation and the richness of threatened birds, and avifauna responses to habitat loss. Fifty steppe remnants distributed throughout Spain and inhabited by Dupont's lark Chersophilus duponti, an endangered passerine representative of shrub steppe-like habitat, were studied. The study fragments were generally affected by agriculture exploitation, and steppe cover had significantly decreased in several isolated patches during the period 1991–1999. Steppe habitat recovered slightly in areas with low plant productivity indices, and decreased in extent in the most productive areas, in line with EU (European Union) agricultural policy recommendations to abandon marginal land of low productivity. The low overall primary productivity of Iberian steppes opened the way to industrial activities (mining, waste collection and wind-farming), which in the study areas occurred more frequently in steppe than in other habitat types that are more attractive to the public (woodland) or more productive (farmland). The emerging wind industry little affected the study plots, but the presence of anemometers suggests that the impact is likely to increase in the near future, especially in the largest steppelands. Dupont's lark was sensitive to the fragmentation of its habitat; crowding occurred in isolated and small fragments, possibly as a consequence of habitat constraints and species dispersal dynamics. Fragments inhabited by Dupont's lark also hosted other steppe birds with a high conservation value; the community of endangered birds, mostly adapted to arid conditions, was richest in the less productive sites. Only four shrub-steppe fragments are given some kind of protection throughout Spain, testifying to the limited public awareness about the value of this habitat. Urgent action is required to restore this habitat through abandonment of less productive farmland, and to create a network of protected and connected steppelands, in order to assure the long-term viability of steppe specialists and the preservation of a habitat that is unique in Western Europe. This should be coupled to an effort to increase social consciousness of the ecological value of steppes and arid landscapes in general.
Development of subsurface warm water in the East China Sea in fall
Authors: Chen Xianyao , Qiao Fangli , Ge Renfeng , Xia Changshui , Yuan Yeli
Published: August 2006

The development of subsurface warm water (SSWW) in the East China Sea (ECS) in fall is analyzed using two observational data sets and the results of a one‐dimensional numerical model. During October, the SSWW is developed in the ECS and remains till the end of November. The analysis shows that it is the Changjiang River (also known as Yangtze River) diluted water (CRDW) that maintains the vertical structure of water column with a subsurface maximum temperature in this region. In fall, the diluted water flows southward in the ECS, leading to a lower salinity layer in the upper ocean. The existence of this lower salinity layer limits the depth of the vertical mixing induced by the loss of heat on the sea surface in fall, and therefore, maintains the higher temperature of the subsurface water. In winter, when the density's vertical gradient of the low salinity layer cannot balance the negative surface buoyancy flux, the SSWW vanishes. However, this situation does not occur outside the region where the CRDW extends, because the stratification becomes unstable while the sea surface loses heat and the convective overturn will readjust the whole water column. Numerical results of a one‐dimensional model reveal that the SSWW appears if the impact of the CRDW is included in the model; otherwise, the SSWW does not occur.
Crack azimuths on Europa: Sequencing of the northern leading hemisphere
Authors: Sarid Alyssa Rose , Greenberg Richard , Hurford T. A.
Published: August 2006

Nonsynchronous rotation of Europa should result in a periodic change in stress azimuths at any given location, which may result in a corresponding change in crack azimuths. An early study seemed to provide evidence for such variation within a crack sequence in the northern trailing hemisphere. However, more recent work with higher‐resolution imagery resulted in a more complete sequence of cracks in the region and showed that the azimuth variation with time was not systematic. Similar results were found in the southern leading region. Here we investigate whether the northern leading region contains a crack record, on the basis of crosscutting relationships, that is adequate to indicate nonsynchronous rotation. As in the previous studies of other regions, we find no clear evidence of nonsynchronous rotation within crack azimuth patterns. However, there are other lines of evidence in support of nonsynchronous rotation. Therefore the lack of a continuous pattern of azimuth change with time is likely due to only a few cracks forming per cycle, thus hiding any discernable signal from nonsynchronous rotation in those regions. In that case, the cracks would have formed over numerous cycles of nonsynchronous rotation. The study also reveals a distinctive distribution of crack azimuths, with gaps at certain values. This distribution may reflect a combination of observation selection due to illumination and less‐favorable cracking orientations.
Role of transient water pressure in quarrying: A subglacial experiment using acoustic emissions
Authors: Cohen D. , Hooyer T. S. , Iverson N. R. , Thomason J. F. , Jackson M.
Published: August 2006

Probably the most important mechanism of glacial erosion is quarrying: the growth and coalescence of cracks in subglacial bedrock and dislodgement of resultant rock fragments. Although evidence indicates that erosion rates depend on sliding speed, rates of crack growth in bedrock may be enhanced by changing stresses on the bed caused by fluctuating basal water pressure in zones of ice‐bed separation. To study quarrying in real time, a granite step, 12 cm high with a crack in its stoss surface, was installed at the bed of Engabreen, Norway. Acoustic emission sensors monitored crack growth events in the step as ice slid over it. Vertical stresses, water pressure, and cavity height in the lee of the step were also measured. Water was pumped to the lee of the step several times over 8 days. Pumping initially caused opening of a leeward cavity, which then closed after pumping was stopped and water pressure decreased. During cavity closure, acoustic emissions emanating mostly from the vicinity of the base of the crack in the step increased dramatically. With repeated pump tests this crack grew with time until the step's lee surface was quarried. Our experiments indicate that fluctuating water pressure caused stress thresholds required for crack growth to be exceeded. Natural basal water pressure fluctuations should also concentrate stresses on rock steps, increasing rates of crack growth. Stress changes on the bed due to water pressure fluctuations will increase in magnitude and duration with cavity size, which may help explain the effect of sliding speed on erosion rates.