bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Axial Ligation or π–π‐Type Interactions on Photochemical Charge Stabilization in “Two‐Point” Bound Supramolecular Porphyrin–Fullerene Conjugates
Authors: D'Souza Francis , Chitta Raghu , Gadde Suresh , Zandler Melvin E. , McCarty Amy L. , Sandanayaka Atula S. D. , Araki Yasuyaki , Ito Osamu
Published: May 2005

Two types of structurally well‐defined, self‐assembled zinc porphyrin–fullerene conjugates were formed by “two‐point” binding strategies to probe the effect of axial ligation or π–π‐type interactions on the photochemical charge stabilization in the supramolecular dyads. To achieve this, meso‐tetraphenylporphyrin was functionalized to possess one or four [18]crown‐6 moieties at different locations on the porphyrin macrocycle while fullerene was functionalized to possess an alkyl ammonium cation, and a pyridine or phenyl entities. As a result of the crown ether–ammonium cation complexation, and zinc–pyridine coordination or π–π‐type interactions, stable zinc porphyrin–fullerene conjugates with defined distance and orientation were formed. Evidence for the zinc–pyridine complexation or π–π‐type interactions was obtained from the spectral and computational studies. Steady‐state and time‐resolved emission studies revealed efficient quenching of the zinc–porphyrin singlet excited state in these dyads, and the measured rates of charge separation, kCS were found to be slightly better in the case of the dyads held by axial coordination and crown ether–cation complexation. Nanosecond transient absorption studies provided evidence for the electron transfer reactions, and these studies also revealed charge stabilization in these dyads. The lifetimes of the radical ion pairs were found to depend upon the type of porphyrins utilized to form the dyads, that is, porphyrin possessing the crown ether moiety at the ortho position of one of the phenyl rings yielded prolonged charge stabilized states. Addition of pyridine to the supramolecular dyads eliminated the zinc–pyridine coordination or π–π‐type interactions of the “two‐point” bound systems due to the formation of a new zinc–pyridine axial bond thus giving a unique opportunity to probe the effect of axial coordination or π–π interactions on kCS and kCR. Under these conditions, the measured electron transfer rates revealed faster kCS and slower kCR as compared to those obtained in the absence of added pyridine. The evaluated lifetimes of the radical ion‐pairs were found to be hundreds of nanoseconds and were longer in the presence of pyridine.
Analysis of force generation during flagellar assembly through optical trapping of free‐swimming Chlamydomonas reinhardtii
Authors: McCord Rachel Patton , Yukich John N. , Bernd Karen K.
Published: May 2005

Many studies have used velocity measurements, waveform analyses, and theoretical flagella models to investigate the establishment, maintenance, and function of flagella of the biflagellate green algae Chlamydomonas reinhardtii. We report the first direct measurement of Chlamydomonas flagellar swimming force. Using an optical trap (“optical tweezers”) we detect a 75% decrease in swimming force between wild type (CC124) cells and mutants lacking outer flagellar dynein arms (oda1). This difference is consistent with previous estimates and validates the force measurement approach. To examine mechanisms underlying flagella organization and function, we deflagellated cells and examined force generation during flagellar regeneration. As expected, fully regenerated flagella are functionally equivalent to flagella of untreated wild type cells. However, analysis of swimming force vs. flagella length and the increase in force over regeneration time reveals intriguing patterns where increases in force do not always correspond with increases in length. These investigations of flagellar force, therefore, contribute to the understanding of Chlamydomonas motility, describe phenomena surrounding flagella regeneration, and demonstrate the advantages of the optical trapping technique in studies of cell motility. Cell Motil. Cytoskeleton 61:137–144, 2005. © 2005 Wiley‐Liss, Inc.
Similar long‐term results of breast‐conservation treatment for Stage I and II invasive lobular carcinoma compared with invasive ductal carcinoma of the breast
Authors: Santiago Roberto J. , Harris Eleanor E. R. , Qin Li , Hwang Wei‐Ting , Solin Lawrence J.
Published: May 2005

BACKGROUND

The objective of the current study was to determine the long‐term results of breast‐conservation treatment in women with early‐stage, invasive lobular carcinoma of the breast.

METHODS

Between 1977 and 1995, 1093 women with Stage I and II invasive ductal carcinoma of the breast and 55 women with invasive lobular carcinoma of the breast underwent lumpectomy, axillary lymph node dissection, and radiation treatment. Overall, 49% of the women received adjuvant systemic therapy (chemotherapy and/or hormones).

RESULTS

The median age was 52 years for patients in the invasive ductal group and 54 years for patients in the invasive lobular group. The median follow‐up was 8.7 years and 10.2 years for patients in the invasive ductal and invasive lobular groups, respectively. A comparison of patients who had invasive lobular carcinoma with patients who had invasive ductal carcinoma showed no difference in the 10‐year actuarial rates of overall survival (85% vs. 79%, respectively; P = 0.73), cause‐specific survival (93% vs. 84%, respectively; P = 0.85), or freedom from distant metastases (81% vs. 80%, respectively; P = 0.76). The 10‐year rates of local failure were 18% for patients with invasive lobular carcinoma and 12% for patients with invasive ductal carcinoma (P = 0.24), and the 10‐year rates of contralateral breast carcinoma development for the 2 groups were 12% and 8%, respectively (P = 0.40).

CONCLUSIONS

Breast‐conservation treatment yielded similar long‐term results for women with early‐stage, invasive lobular carcinoma and women with the more prevalent invasive ductal carcinoma. Cancer 2005. © 2005 American Cancer Society.
Interobserver reliability of computed tomography‐derived primary tumor volume measurement in patients with supraglottic carcinoma
Authors: Mukherji Suresh K. , Toledano Alicia Y. , Beldon Clifford , Schmalfuss Ilona M. , Cooper Jay S. , Sicks JoRean D. , Amdur Robert , Sailer Scott , Loevner Laurie A. , Kousouboris Phil , Ang Kian
Published: May 2005

BACKGROUND

Prior studies have determined that macroscopic (“gross”) tumor volume (GTV), as calculated from pretreatment computer tomography (CT), was capable of predicting local control in squamous cell carcinoma arising in different subsites in the head and neck in patients who were treated with nonsurgical organ‐preservation therapy. The majority of these studies were single‐institution, retrospective investigations. Consequently, there has been concern that GTV measurements may not be reproducible by different readers at different institutions. The objective of the current study was to measure the interobserver reliability for GTV measurements for squamous cell carcinoma of the supraglottic larynx (SGSCCA) performed by different readers at different institutions.

METHODS

Eight experienced readers (4 neuroradiologists and 4 radiation oncologists) from different institutions independently measured the pretreatment GTV of 20 patients with SGSCCA. The CT scans were obtained from patients entered into the definitive radiation therapy arm of Radiation Therapy Oncology Group protocol 91‐11, who had supraglottic carcinoma and underwent pretreatment CT scans of the neck. Statistical analysis focused on interobserver reliability as measured by the intraclass correlation coefficient.

RESULTS

The intraclass correlation coefficient was 0.81 (95% lower confidence bound, 0.71). This value was interpreted as “excellent.”

CONCLUSIONS

GTV measurements were reliable and reproducible when performed by neuroradiologists and radiation oncologists who were experienced in the interpretation of CT scans of the extracranial head and neck in patients with SGSCCA. The result implied that the correlation between GTV and local control should be reproducible across institutions. Cancer 2005. © 2005 American Cancer Society.
Energy‐adjustable mechanism of the combined hybrid finite element method and improvement of Zienkiewicz's plate‐element
Authors: Xie Xiao‐ping , Hu Jian‐cheng
Published: May 2005

The combined hybrid finite element method for plate bending problems allows arbitrary combinations of deflection interpolation and bending moment approximations. A novel expression of the approach discloses the energy‐adjustable mechanism of the hybrid variational principle to enhance accuracy and stability of displacement‐based finite element models. For a given displacement approximation, appropriate choices of the bending moment mode and the combination parameter α ∈ (0,1) can lead to accurate energy approximation which generally yields numerically high accuracy of the displacement and bending moment approximations. By virtue of this mechanism, improvement of Zienkiewicz's triangular plate‐element is discussed. The deflection is approximated by Zienkiewicz incomplete cubic interpolation. And three kinds of bending moments approximations are considered: a 3‐parameter constant mode, a 5‐parameter incomplete linear mode, and a 9‐parameter linear mode. Since the parameters of the assumed bending moments modes can be eliminated at an element level, the computational cost of the combined hybrid counterparts of Zienkiewicz's triangle are as same as that of Zienkiewicz's triangle. Numerical experiments show that the combined hybrid versions can attain high accuracy at coarse meshes. Copyright © 2005 John Wiley & Sons, Ltd.
Analysis of multiscale methods for stochastic differential equations
Authors: Weinan E , Liu Di , Vanden‐Eijnden Eric
Published: May 2005

We analyze a class of numerical schemes proposed [26] for stochastic differential equations with multiple time scales. Both advective and diffusive time scales are considered. Weak as well as strong convergence theorems are proven. Most of our results are optimal. They in turn allow us to provide a thorough discussion on the efficiency as well as optimal strategy for the method. © 2005 Wiley Periodicals, Inc.
The Influence of Solid‐State Molecular Organization on the Reaction Paths of Thiyl Radicals
Authors: Faucitano Antonio , Buttafava Armando , Mariani Mario , Chatgilialoglu Chryssostomos
Published: May 2005

Electron paramagnetic resonance (EPR) spectroscopy has been employed to investigate the effect of solid‐state molecular organization on the reaction of thiyl radicals with thiols. In an irradiated C18H37SH/thiourea clathrate, the conversion of thiyl to perthiyl radicals is substantial, due to the head‐to‐head arrangement of the reactants within the channels and the suppression of other possible competing reactions due to hindrance by the clathrate walls. The perthiyl radical was identified using EPR analysis of its molecular dynamics within the clathrate channels. Irradiated polyethylene film containing 30 % C18H37SH afforded a negligible conversion of thiyl to perthiyl radicals because of the random distribution of reactants. These results suggest that in the absence of favorable structure‐control effects, the reaction between RS. and RSH is unimportant with respect to other competing reactions. Perthiyl radicals are also the major product in the vacuum solid‐state radiolysis of lysozyme. A proposal of the mechanism involved in all cases is based on the equilibrium RS.+RSH⇌RSS.(H)R, followed by the irreversible conversion of the sulfuranyl radical to the perthiyl radical. As the equilibrium is strongly shifted to the left, the intermediate sulfuranyl radicals were not detected, but the lack of other competing reactions for the thiyl radicals caused the formation of perthiyl radicals to become the major path in the clathrate and in solid lysozyme radiolysis.
Probing Binding‐Mode Diversity in Guanidinium–Oxoanion Host–Guest Systems
Authors: Haj‐Zaroubi Manal , Schmidtchen Franz P.
Published: May 2005

An attempt to experimentally estimate the role of binding‐mode diversity (structural fuzziness) on the molecular recognition seen in the prominent guanidinium–oxoanion host–guest pair is described. The global heat response as measured by isothermal titration calorimetry in acetonitrile, which was obtained from the interaction of five different but structurally closely related guanidinium hosts with three rigid phosphinate guests of decreasing accessibility of their binding sites, is correlated to provide a trend analysis. All host–guest associations of 1:1 stoichiometry in this series are strongly enthalpy‐driven. The change in complexation entropy can be related to the tightness of the mutual fit of the host–guest partners, which approaches a minimum limit and is interpreted as the unique lock‐and‐key binding mode. The ordinary host–guest complexation in this ensemble features substantial positive entropy changes that correlate inversely with the binding interface area. This finding excludes desolvation effects as the major cause of entropy production, and provides evidence for the existence of a broad variety of complex configurations rather than a single binding mode to represent the associated host–guest pair. This result bears on the molecular design of systems that vitally depend on structural fidelity, such as nanoassemblies or homogeneous catalysis.
A Computational Study of Thiolate and Selenolate Oxidation by Hydrogen Peroxide
Authors: Cardey Bruno , Enescu Mironel
Published: May 2005

Ab initio molecular orbital calculations have been used to study the effects of the molecular environment on the oxidation of thiolate and selenolate by hydrogen peroxide. The reaction was first examined in vacuo at the QCISD(T)/6‐311+G(2df,2pd)//MP2/6‐311+G(d,p) level of theory. It was found for both thiolate and selenolate that a reactant aggregate is formed, which has a dissociation rate constant comparable to the activation rate constant (about 10−3 s−1 for thiolate and 10−1 s−1 for selenolate). Using the polarizable continuum model (PCM) it was then found that the dissociation barrier energy decreases dramatically in water giving a dissociation rate constant of the order of 109 s−1. In this case, the predicted overall rate constant of the thiolate reaction was about 10.2 mol−1 dm3 s−1, which is in good agreement with the experimental rate constant of cysteine oxidation in aqueous solution. The calculated rate constant for the selenolate reaction was somewhat higher (about 35.4 mol−1 dm3 s−1). However, this value is several orders of magnitude smaller than the experimental value reported for the oxidation of selenocysteine in glutathione peroxidase. By considering the effect of the PCM dielectric constant on the reaction rate constant it was concluded that the high reactivity of the selenocysteine in glutathione peroxidase, as compared with cysteine, could be mainly due to the molecular environment of the selenocysteine residue.
Mesoscopic Structures of Maghemite Nanocrystals: Fabrication, Magnetic Properties, and Uses
Authors: Pileni Marie‐Paule , Ngo Anh‐Tu
Published: May 2005

Mesoscopic structures made of maghemite (γ‐Fe2O3) nanocrystals with different coatings and shapes are described. They are controlled by a combination of van der Waals and magnetic dipolar interactions and their shapes are responsible for the collective magnetic response of the nanocrystals. It is shown that spherical γ‐Fe2O3 nanocrystals can be used as a mask to reproduce the mesoscopic structure on a silicon wafer.
Switching Mechanism in Polar Columnar Mesophases Made of Bent‐Core Molecules
Authors: Gorecka Ewa , Vaupotič Nataša , Pociecha Damian , Čepič Mojca , Mieczkowski Jozef
Published: May 2005

The behaviour of polar, broken‐layer‐type columnar phases made of bent molecules (B1Rev and B1RevTilted) was studied under an applied electric field. There are two competing mechanisms of ferroelectric switching in the polar B1RevTilted columnar phase: collective rotation around the long molecular axis and collective rotation around the tilt cone. The proposed model shows that the main factor discriminating the type of switching is the width of the column cross‐section.
Particle Distribution in a Microporous Material: Experiments with Zeolite A
Authors: Meyer Marc , Leiggener Claudia , Calzaferri Gion
Published: May 2005

The theory on particle distribution and exchange equilibria in a microporous material is applied to experimental ion‐exchange data involving zeolite Na‐A and zeolite K‐A, with silver ions as the exchanging species. The presented method enables direct evaluation of the measured data and consideration of nonequivalent particle sites. The isotherms of the K+ versus Ag+ exchange in zeolite K‐A rise much more steeply, at low exchange degrees, than those of the Na+ versus Ag+ exchange in zeolite Na‐A. This result implies a different course of the ion‐exchange reactions. Spectroscopic measurements on dehydrated, partly silver‐exchanged zeolites Na‐A and K‐A do indeed show that in zeolite Na‐A, the Na+ ions occupying four‐ring positions are exchanged faster for Ag+ than the Na+ ions occupying eight‐ and six‐ring positions, while in zeolite K‐A the exchange does not start with the four‐ring ion but with six‐ring ions, followed by the four‐ring ion. These findings are consistent with the results obtained from evaluation of the ion‐exchange data. The resulting thermodynamic quantities significantly differ from published reference values, which we suggest should be revised.
RBMX gene is essential for brain development in zebrafish
Authors: Tsend‐Ayush Enkhjargal , O'Sullivan Lynda A. , Grützner Frank S. , Onnebo Sara M.N. , Lewis Rowena S. , Delbridge Margaret L. , Marshall Graves Jennifer A. , Ward Alister C.
Published: May 2005

The human RBMX gene was discovered recently through its homology to the spermatogenesis candidate gene RBMY. Its position on the human X chromosome suggests that it may be involved in X‐linked mental retardation syndromes. However, to date there is scant information on the in vivo role of RBMX. To address this issue, we have isolated a zebrafish rbmx orthologue and characterized its embryonic expression pattern. Zebrafish rbmx is maternally expressed and then widely expressed in the embryo up to 24 hr postfertilization. In later stages of embryonic development, rbmx transcripts are localized predominantly in the brain, branchial arches, and liver primordium. The function of rbmx during embryonic development was examined by the use of an antisense morpholino targeting rbmx. The rbmx‐morphants displayed an underdeveloped head and eyes, reduced body size, defective somite patterning, and absence of jaws. Furthermore, in the absence of functional rbmx, expression of specific markers for the fore‐ and hindbrain (otx2, krox20) was severely reduced. These studies demonstrate for the first time that rbmx is required for normal embryonic development, in particular of the brain, consistent with a role in X‐linked mental retardation. Developmental Dynamics 234:682–688, 2005. © 2005 Wiley‐Liss, Inc.
Fabricating of Acetylcholine Biosensor by a Layer‐by‐layer Deposition Technique for Determining Trichlorfon
Authors: Shi Haibin , Zhao Zixia , Song Zhao , Huang Jiadong , Yang Yu , Anzai Jun‐ichi , Osa Tetsuo , Chen Qiang
Published: May 2005

An acetylcholine (ACh) biosensor has been fabricated with bienzymes/poly(diallyldimethylammonium chloride) (PDDA) multilayer film‐modified platinum (Pt) electrodes by a layer‐by‐layer technique (LBL). The ACh biosensor was optimized and the properties are described. This ACh biosensor was used for the detection of organophosphate pesticide trichlorfon. The detection limits (found 0.001 μg/mL for trichlorfon) make it possible to detect the pollutants. This simple protocol of biosensor preparation, high sensitivity and stability are very promising for the determination of environmental pollutants in field conditions.
Polycrystalline Gold Electrodes: A Comparative Study of Pretreatment Procedures Used for Cleaning and Thiol Self‐Assembly Monolayer Formation
Authors: Carvalhal Rafaela Fernanda , Sanches Freire Renato , Kubota Lauro Tatsuo
Published: May 2005

The influence of different surface pretreatment procedures on the electrochemical response of a polycrystalline gold electrode was evaluated. Mechanical polishing with slurry alumina (M), chemical oxidation with H2SO4/H2O2 (C), electrochemical polishing (potential cycling between −0.1 V and 1.2 V vs. SCE) (E), chemical reduction with ethanol, and combinations among these treatments were employed to change the surface electrode characteristics. The efficiency of the proposed pretreatments was evaluated by electrochemical responses towards the redox couple ferri(II/III)‐ammonium sulfate and by the formation of a self‐assembly monolayer of 3‐mercaptopropionic acid (3 MPA SAM) on gold electrodes. The procedure (C) allowed important gold surfaces activation. Using procedures (C) and (E) the roughness of polycrystalline gold surfaces was significantly minimized and more reproducible surfaces could be obtained. From the profile of reductive desorption of 3 MPA SAM it was possible to verify that reduced gold surfaces generated better packed monolayers than oxidized ones and a comparative study using CV and DPV techniques showed that between the two desorption peaks, the one localized at more negative potential values corresponds to the cleavage of Au‐S bond from the chemisorbed thiol. In general, the improvement in the studied electrochemical responses could not only be attributed to an increase in the real surface area of the electrode, but to the chemical surface states set off by the pretreatment procedure.
Sensitivity and Selectivity of Polypyrrole Based AC‐Amperometric Sensors for Electroinactive Ions – Frequency and Applied Potential Influence
Authors: Walkiewicz Sebastian , Michalska Agata , Maksymiuk Krzysztof
Published: May 2005

Oxidation/reduction of polypyrrole films coupled with ion exchange on the polymer/solution interface can be utilized for amperometric sensing of electroinactive ions. Anion or cation exchanging films (polypyrrole doped by chloride or poly(4‐styrenesulfonate) ions, respectively) can be used to determine common anions (as Cl−, NO$\rm{ {_{3}^{-}}}$, SO$\rm{ {_{4}^{2-}}}$ etc) or cations (K+, Na+, Li+, Ca2+, Mg2+) under conditions of alternating current (AC) amperometry in the range 10−4–1 M. A sensitivity can be tuned by choosing appropriate electrode potential, corresponding to polypyrrole oxidation (anion‐exchanging films) or reduction (cation‐exchangers). Electrochemical impedance spectroscopy and AC‐voltammetry studies have shown that applied frequency and potential could also affect the observed dependence of the signal (admittance or AC‐current) on ion concentration. For high frequency the sensitivity is higher but selectivity lower, due to influence of solution conductivity on the response. For low frequencies the sensitivity is lower; however, a selectivity increase was observed due to diverse mobility of ions in the polymer film. Selectivity of AC‐amperometric responses was studied both in separate and mixed solutions.
Comparative analysis of the mutagenic activity of oxaliplatin and cisplatin in the Hprt gene of CHO cells
Authors: Silva Maria J. , Costa Paula , Dias Anabela , Valente Marco , Louro Henriqueta , Boavida Maria G.
Published: May 2005

Oxaliplatin is a platinum‐derived antitumor drug that is active against cisplatin‐resistant tumors and has lower overall toxicity than does cisplatin. DNA adduct formation is believed to mediate the cytotoxic activity of both compounds; however, the adducts may also be responsible for mutagenic and secondary tumorigenic activities. In this study, we have compared the mutagenicity of oxaliplatin and cisplatin in the Hprt gene of CHO‐K1 cells. Both drugs produced dose‐related increases in mutant frequency. For 1‐hr treatments, oxaliplatin was less mutagenic than cisplatin at equimolar doses, while similar mutant frequencies were induced at equitoxic doses. Sequencing of mutant Hprt genes indicated that the mutation spectra of both oxaliplatin and cisplatin were significantly different from the spontaneous mutation spectrum (P = 0.014 and P = 0.008, respectively). A significant difference was also observed between the spectra of oxaliplatin‐ and cisplatin‐induced mutations (P = 0.033). Although G:C→T:A transversion was the most common mutation produced by both compounds, oxaliplatin produced higher frequencies of A:T→T:A transversion than did cisplatin, most commonly at nucleotide 307, and higher frequencies of small deletions/insertions. Also, cisplatin induced tandem base‐pair substitutions, mainly at positions 135/136, and a higher frequency of G:C→A:T transition than did oxaliplatin. These results provide the first evidence that oxaliplatin is mutagenic and that the profiles of cisplatin‐ and oxaliplatin‐induced mutations display not only similarities but also distinctive features relating to the type and sequence‐context preference for mutation. Environ. Mol. Mutagen., 2005. © 2005 Wiley‐Liss, Inc.
Contribution of BRCA1 and BRCA2 germ‐line mutations to the incidence of breast cancer in young women: Results from a prospective population‐based study in France
Authors: Bonadona Valerie , Sinilnikova Olga M. , Chopin Sandrine , Antoniou Antonis C. , Mignotte Hervé , Mathevet Patrice , Brémond Alain , Martin Alain , Bobin Jean‐Yves , Romestaing Pascale , Raudrant Daniel , Rudigoz René‐Charles , Léoné Mélanie , Chauvin Franck , Easton Douglas F. , Lenoir Gilbert M , Lasset Christine
Published: May 2005

The prevalence of BRCA1/2 germ‐line mutations was assessed in a prospective population‐based series of early‐onset breast cancer (BC) patients in France, and the usefulness of a clinical assessment of hereditary BC risk, based on multiple criteria including pedigree structure, was evaluated. Through the Rhône region BC registry, 232 women diagnosed with BC before 46 years of age were included. They were tested for BRCA1/2 mutations an average of 10 months after diagnosis. All the women were classified according to their family history of cancer: high risk of hereditary breast cancer (HBC), low risk of HBC, isolated BC, and unknown HBC risk. Deleterious mutations were observed in 21 women (9.1%): 15 (6.5%) BRCA1 and 6 (2.6%) BRCA2. Mutations were more prevalent in women who developed BC before age 41 than in women who developed BC between ages 41 and 45 (12.8% versus 5.2%, respectively, P = 0.04). A high prevalence of BRCA1/2 mutations was found among women in the high‐risk category with particular family features (i.e., small family size, predominantly male pedigree, specific cancers; 23.5%) and among women with isolated BC before age 41 and with five or fewer close adult female relatives (16.6%). According to the 10% probability level recommended by the American Society of Clinical Oncology guidelines for genetic testing of cancer, BRCA1/2 mutation screening should be considered for all women diagnosed before age 41, except for those with isolated BC in a large pedigree including multiple unaffected female relatives. The clinical assessment of HBC risk that we have developed should help in the decision to perform genetic testing. © 2005 Wiley‐Liss, Inc.
ETV6 gene rearrangements in invasive breast carcinoma
Authors: Letessier Anne , Ginestier Christophe , Charafe‐Jauffret Emmanuelle , Cervera Nathalie , Adélaïde José , Gelsi‐Boyer Véronique , Ahomadegbe Jean‐Charles , Benard Jean , Jacquemier Jocelyne , Birnbaum Daniel , Chaffanet Max
Published: May 2005

The ETV6/TEL gene encodes a transcription factor frequently rearranged in several types of cancer. We looked for ETV6 rearrangements in invasive breast cancer using fluorescence in situ hybridization (FISH) of BAC probes on sections of tissue microarrays containing 632 tumor samples. Of these samples, signal of sufficient quality for screening by FISH was obtained for 356. Five cases (one lobular, one nontypical secretory, one mixed, and two ductal carcinomas) showed ETV6 rearrangement. © 2005 Wiley‐Liss, Inc.
Progressive loss of the spongiotrophoblast layer of Birc6/Bruce mutants results in embryonic lethality
Authors: Hitz Christiane , Vogt‐Weisenhorn Daniela , Ruiz Patricia , Wurst Wolfgang , Floss Thomas
Published: May 2005

We have generated a mouse line with a mutant allele of the mouse Bruce/Birc6 gene induced by gene trap mutagenesis. Based on its structural features, Bruce is a member of the family of apoptosis inhibitor proteins (IAPs). This mutation leads to a truncated transcript and protein and results in a complete loss of the wildtype Bruce protein. Bruce mutant mice die from a progressive loss of their placental spongiotrophoblast layer between day 11.5 and 14.5 of embryonic development. The cause of the Bruce homozygous mutant phenotype is a lack of proliferation of spongiotrophoblast cells in the developing placenta. In contrast to in vitro data, which indicate a function for Bruce in apoptosis inhibition, the in vivo results presented here suggest instead a role for Bruce in cell division. genesis 42:91–103, 2005. © 2005 Wiley‐Liss, Inc.
Deconstructing helicoplacoids: reinterpreting the most enigmatic Cambrian echinoderms
Authors: Sprinkle James , Wilbur Bryan C.
Published: May 2005

Helicoplacoids, the most enigmatic group of Early Cambrian echinoderms, have a spirally plated, inverted pear‐ to spindle‐shaped theca with numerous interambulacral pleats and a long triradiate ambulacrum. They occur in western Laurentia along with the earliest edrioasteroids and epispire‐bearing eocrinoids(?), but unlike these other groups, helicoplacoids do not show pentameral symmetry around a centrally located, upward‐facing mouth. It is uncertain where the major body openings were located in helicoplacoids, where new plates were added during thecal growth, and whether helicoplacoids were primitive, pre‐pentameral, stem‐group echinoderms or derived, relatively specialized forms that had lost several ambulacra.

We made highly modified, side‐layout, plating diagrams of different helicoplacoid species by cutting the theca apart half‐way between the spiraling ambulacra, leaving four to six interambulacral pleats on each side. This deconstructed thecal strip resulted in an elongate sigmoid‐shaped plating diagram with a long central single or paired ambulacrum that is interpreted as three ambulacral branches (A down, C and D up) around a central mouth on the side of the theca. The unrolled plating diagram resembles an elongate French curve drawing template with nearly parallel sides, a large or small sigmoidal top (where the theca is rounded and the interambulacral pleats converge), and an open deviated bottom, where the interambulacral pleats turn down to a truncated conical base. The two upward‐extending ambulacra are only one to two interambulacral pleats apart, which only slightly increases the plating strip width. New interambulacral plates are added at the summit and base, and interambulacral pleats rarely branch elsewhere. New floor and cover plates are added at the top and bottom distal ambulacral tips. If this plating model is correct, the anus (which has still not been identified) should be located near the thecal summit where the C and D ambulacra end, and all imperforate extraxial plating has apparently been lost from the theca.

If upright, spirally pleated helicoplacoids with three ambulacra were derived from attached, domal or pyrgate, pentameral edrioasteroids, numerous changes must have occurred in the thecal shape, number of ambulacra, and interambulacral areas. These changes either occurred gradually in a sequence, or a single major change (spiralled body form?) caused all the others to rapidly follow. Copyright © 2005 John Wiley & Sons, Ltd.
Monitoring over‐winter soil water dynamics in a freezing and snow‐covered environment using a thermally insulated tensiometer
Authors: Iwata Yukiyoshi , Hirota Tomoyoshi
Published: May 2005

Water potential below a frozen soil layer was continuously monitored over an entire winter period (using thermally insulated tensiometers sheltered in a heated chamber) along with other soil, snow and atmospheric variables. In early winter, the freezing front advanced under a thin snow cover, inducing upward soil water flow in the underlying unfrozen soil. The freezing front started to retreat when the snow cover became thick enough to insulate the soil, resulting in the reversal of the flow direction in the unfrozen zone. These data provide a clear illustration of soil water dynamics, which have rarely been monitored with a tensiometer. Copyright © 2005 John Wiley & Sons, Ltd.
Effects of grid cell size and time step length on simulation results of the Limburg soil erosion model (LISEM)
Authors: Hessel Rudi
Published: May 2005

With increasing computer power, process‐based models that use grids to discretize space have become increasingly popular. For such models, the simulation results might depend on both grid cell size and, in the case of dynamic models, on the time step length used in the model. In this study, the dynamic Limburg soil erosion model (LISEM) was applied to a small catchment on the Chinese Loess Plateau. To study the effect of grid cell size and time step length, simulations were performed for grid cell sizes ranging from 5 to 100 m for a single time step length, and for time step lengths ranging from 2 to 120 s for a single grid cell size. The results show that the LISEM results vary considerably as a function of both grid cell size and time step length. For both increase in cell size and increasing time step length, the trend was a decrease in predicted discharge and predicted soil loss. For discharge, the most important causes are likely to be a decrease in slope with increasing grid cell size, rainfall averaging for longer time step lengths, and numerical dispersion of the kinematic wave solution. For soil loss, the cause is less clear, reflecting the complexity of soil loss prediction, which depends on available water, transport capacity and sediment redistribution, all of which change in time and space. These results show that a choice for a certain grid cell size and a certain time step length should be made before calibration of the model. Similar erosion models are likely to have similar dependencies on grid size and time step length. Copyright © 2005 John Wiley & Sons, Ltd.
Using recurrent neural networks to reconstruct rainfall‐runoff processes
Authors: Pan Tsung‐yi , Wang Ru‐yih
Published: May 2005

Many novel techniques for reconstructing rainfall‐runoff processes require hydrometeorologic and geomorphologic information for modelling. However, certain information is not always measurable. In this paper, we employ a special recurrent neural network to reconstruct the rainfall‐runoff process by using collected rainfall data. In addition, we propose an indirect system identification to overcome the drawback of a traditional, time‐consuming trial‐and‐error search. The indirect system identification is an efficient method to recognize the structure of a recurrent neural network. The unit hydrograph can be derived directly from the weights of the network due to a state‐space form embedded in the recurrent neural network. This improves the link between the weights of the network and the physical concepts that most neural networks fail to connect.

The case studies of 41 events from 1966 to 1997 have been implemented in Taiwan's Wu‐Tu watershed, where the runoff path‐lines are short and steep. Two recurrent neural networks and one state‐space model are utilized to simulate the rainfall‐runoff processes for comparison. The results are validated by four criteria: coefficient of efficiency; peak discharge error; time to peak arrival error; total discharge volume error. The resulting data from the recurrent neural network reveal that the neural network proposed herein is appropriate for hydrological systems. Copyright © 2005 John Wiley & Sons, Ltd.
Modelling snowpack surface temperature in the Canadian Prairies using simplified heat flow models
Authors: Raj Singh Purushottam , Yew Gan Thian
Published: May 2005

Three practical schemes for computing the snow surface temperature Ts, i.e. the force–restore method (FRM), the surface conductance method (SCM), and the Kondo and Yamazaki method (KYM), were assessed with respect to Ts retrieved from cloud‐free, NOAA‐AVHRR satellite data for three land‐cover types of the Paddle River basin of central Alberta. In terms of R2, the mean Ts, the t‐test and F‐test, the FRM generally simulated more accurate Ts than the SCM and KYM. The bias in simulated Ts is usually within several degrees Celsius of the NOAA‐AVHRR Ts for both the calibration and validation periods, but larger errors are encountered occasionally, especially when Ts is substantially above 0 °C. Results show that the simulated Ts of the FRM is more consistent than that of the SCM, which in turn was more consistent than that of the KYM. This is partly because the FRM considers two aspects of heat conduction into snow, a stationary‐mean diurnal (sinusoidal) temperature variation at the surface coupled to a near steady‐state ground heat flux, whereas the SCM assumes a near steady‐state, simple heat conduction, and other simplifying assumptions, and the KYM does not balance the snowpack heat fluxes by assuming the snowpack having a vertical temperature profile that is linear. Copyright © 2005 John Wiley & Sons, Ltd.
Annual and seasonal variability in evapotranspiration and water table at a shrub‐covered bog in southern Ontario, Canada
Authors: Lafleur Peter M. , Hember Robbie A. , Admiral Stuart W. , Roulet Nigel T.
Published: May 2005

Evapotranspiration (ET) was measured via the eddy covariance technique at a shrub bog peatland in southeastern Ontario for 5 years. For most of the study period the temperature was above normal. Precipitation was variable, but, in 2 years, late summer dry periods resulted in an extended period of deep drawdown of the water table (WT). Growing‐season (May–September) daily ET varied considerably; maximum ET rates were 4 to 5 mm day−1. Winter ET rates were an order of magnitude smaller than in summer, yet the total winter ET loss was important, accounting for 23 to 30% of the annual ET water loss. Annual precipitation exceeded annual ET by 1·55 to 1·94 times.

During the growing season, daily ET was closely related to daily potential evaporation (PET); however, the slope of this relationship was statistically different in some years. In contrast, ET and WT were only weakly related in most years. When ET was sorted into 5 cm WT classes there was no difference in mean ET across most WT classes; only the two deepest WT classes had significantly smaller mean ET. The ratio ET/PET followed the same pattern. We present a conceptual model of ET that relates WT, soil hydraulic properties and moss and vascular plant processes. Copyright © 2005 John Wiley & Sons, Ltd.
The effects of different input data and their spatial resolution on the results obtained from a conceptual nutrient emissions model: the River Stör case study
Authors: Venohr Markus , Behrendt Horst , Kluge Winfrid
Published: May 2005

This paper focuses on the influences of different data sources, and the variation in spatial resolution of input data and analysis, on the calculated nutrient emissions using the conceptual model MONERIS. MONERIS calculates both nitrogen and phosphorus emissions from point and diffuse sources and the riverine nutrient retention. By subtracting the retention from the emissions, a riverine nutrient load was estimated and compared with the observed nutrient river load. All calculations were conducted for the period from 1991 to 1993.

The River Stör, with a catchment area of 1135 km2, located in a postglacial lowland landscape in northern Germany, was chosen as a case study area. Two different data sets (e.g. land use, soil type or wastewater treatment plant inventory) were used: a commonly available standard data set (German or European maps) and a more detailed set with a higher spatial resolution derived from several studies at the Ecosystem Research Centre in Kiel. Initially, both data sets were used to apply MONERIS to the total catchment. The results were compared to adapt some of the free model‐parameters to the conditions in the relatively small lowland river catchment.

Using the standard data set, total nutrient emissions of 2320 tons year−1 of nitrogen and 96 tons year−1 phosphorus were calculated. The detailed data set yielded slightly higher emissions for nitrogen (2420 tons year−1) and for phosphorus (102 tons year−1). According to the spatial resolution, the proportion of the area of tile drainages and sandy soils derived from the different data sets varies considerably. This causes great differences in the total nutrient emissions estimated by the two approaches. Comparing the observed and the calculated nutrient loads, reliable results for catchments larger than 50 km2, or third‐order streams, could be shown. Copyright © 2005 John Wiley & Sons, Ltd.
Suspended sediment dynamics associated with snowmelt runoff in a small mountain stream of Lake Tahoe (Nevada)
Authors: Langlois Jacques L. , Johnson Dale W. , Mehuys Guy R.
Published: May 2005

The Lake Tahoe basin is experiencing an environmental decline that is partly due to sediment intakes from its tributaries. Many studies have estimated suspended sediment loads in these streams with a discrete sampling programme by collecting water samples and using a rating technique. However, the relationship between stream discharge and suspended sediment concentration (SSC) in these tributaries is known to differ during the rising and falling limbs of the snowmelt‐dominated hydrograph. Because of this hysteresis effect, sediment rating curves are poor predictors of suspended sediment dynamics in the stream. In this study, suspended sediment transport was investigated using a turbidity meter to provide a continuous record of sediment concentration during the snowmelt period. Hysteresis in suspended sediment transport was also investigated and is quantified with an H index, which is the ratio of the areas under the curve at different stages of the hydrograph. The temporal lag between the peak of SSC and the peak of stream discharge was quantified using cross‐correlation analysis. For almost all events, SSCs were higher during the rising limb of the hydrograph for a given discharge, with SSC peaks occurring before discharge peaks, resulting in clockwise hysteresis (H > 1). The H indices increased (looser hysteresis loop) as the availability of sediments increased and as the lag between peaks in SSC and discharge was larger. A restriction of the proposed H index was that it could only be computed when stream discharge increased by more than 30% during a melt event. Copyright © 2005 John Wiley & Sons, Ltd.
Stochastic multiobjective optimization of reservoirs in parallel
Authors: Wang Y. C. , Yoshitani J. , Fukami K.
Published: May 2005

A stochastic multiobjective optimization method for finding noninferior solutions of the operation problem of reservoirs in parallel is presented. This problem is characterized by a multiobjective optimization, a multireservoir system, and stochasticity of inflows, which represent three difficult aspects in reservoir system planning and operation. In this method, a constraint technique, decomposition iteration, and simulation analysis are employed conjunctively to deal with the three difficult aspects. The constraint technique is intended to transform the multiobjective optimization into a uniobjective one and the decomposition iteration in conjunction with the simulation analysis attempts to alleviate the dimensionality problem. The proposed methodology is applied to a reservoir system in the upper Tone River basin, which consists of three reservoirs in parallel and is operated primarily for three objectives: hydropower, water supply, and flood control. A total of 49 noninferior solutions for the reservoir system are obtained, from which the decision makers may be able to find the most satisfactory operating policy. Copyright © 2005 John Wiley & Sons, Ltd.
Long‐term trend analysis for precipitation in Asian Pacific FRIEND river basins
Authors: Xu Z. X. , Takeuchi K. , Ishidaira H. , Li J. Y.
Published: May 2005

In order to analyse the long‐term trend of precipitation in the Asian Pacific FRIEND region, records from 30 river basins to represent the large range of climatic and hydrological characteristics in the study area are selected. The long‐term trend in precipitation time series and its association with the southern oscillation index (SOI) series are investigated. Application of the nonparametric Mann–Kendall test for 30 precipitation time series has shown that only four of these 30 time series have a long‐term trend at the 5% level of significance. Nevertheless, most of the records tend to decrease over the last several decades. The dataset is further divided geographically into northern, middle, and southern zones, with 20°N and 20°S latitude as the dividing lines. The middle zone has the greatest variation and the southern zone the least variation over the past century. Also, the southern zone has greater variation during the past 30 years. The association between precipitation and SOI is investigated by dividing the precipitation records of each station into El Niño, La Niña, and neutral periods. The Wilcoxon rank‐sum test showed that differences in precipitation for the three classes were most marked in the southern zone of the study area. The frequencies of below‐ and above‐average precipitation for El Niño, La Niña, and neutral periods are estimated for the 30 precipitation time series as well. The results show that the frequencies of precipitation under each set of conditions, with lower precipitation generally associated with El Niño periods in the southern zone. Copyright © 2005 John Wiley & Sons, Ltd.
Spatial evolution of nitrogen and phosphorus loads along a small Mediterranean river: implication of bed sediments
Authors: Tournoud Marie‐George , Perrin Jean‐Louis , Gimbert Frédéric , Picot Bernadette
Published: May 2005

This study addresses the spatial variations in water quality along the River Vène (France). The Vène drains a 67 km2 rural basin, with a large karstic area, located in a Mediterranean context. A 1 day sampling campaign was conducted along the river, in winter low‐flow conditions (February 2003). Physico‐chemical parameters and water flow discharge were measured in situ during the sampling campaign. Water quality was evaluated by determining the concentrations of nitrogen and phosphorus in water and bed‐sediment samples. Nitrogen and phosphorus loads were evaluated taking into account the measured concentrations and discharge. The campaign included 18 sampling points and concerned the whole river from the spring to the outlet, plus the main inputs, i.e. sewage treatment works, main tributaries and karstic springs. The spatial evolution of nitrogen and phosphorus loads along the river allowed the significant role of point‐source inputs to be demonstrated. The decrease in nutrient loads along the river occurred mainly in specific reaches where fine sediments had accumulated. In these zones, phosphorus is trapped in the bed sediments in calcium‐bound phosphates due to precipitation processes. Copyright © 2005 John Wiley & Sons, Ltd.