bluuebunny/crossref_metadata_2025 huggingface dataset:
CW‐LD pumped acousto‐optic Q‐switched Nd:YVO4 laser
Authors: Xiu‐Jiang Huang , Ming‐Zhong Li , Zhan Sui , Yong‐Zhi Liu , Yan‐Yong Wang , Yi‐Ming Luo , Hai‐Yan Chen
Published: June 2004

A high‐power continuous‐wave (CW) laser‐diode (LD) pumped acousto‐optic Q‐switched Nd:YVO4 laser is presented. A short pulse at 1064 nm is obtained. With a repetition rate of 50 kHz, a maximum average output power of 5.72 W is achieved. The optical‐conversion efficiency and the slope efficiency are 28% and 32.4%, respectively. At the repetition rate of 10 kHz and the pulse width of 16.3 ns, the maximum single‐pulse energy of 286 μJ and the peak power of 13 kW are acquired. The laser can be used as a signal source for free‐space optical communication. The output signal agrees well with the modulate signal. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 281–283, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20278
A 3‐mW concurrent 2.4/5.2‐GHz dual‐band low‐noise amplifier for WLAN applications in 0.18‐μm CMOS technology
Authors: Lee Tai‐Hsing , Lin Yo‐Sheng
Published: June 2004

A concurrent 2.4/5.2‐GHz dual‐band monolithic low‐noise amplifier implemented with a 0.18‐μm mixed‐signal CMOS technology is reported for the first time. This LNA only consumed 3‐mW power, and achieved minimum noise figures of 3.3 and 3.26 dB and 2.4 and 5.2 GHz, respectively. Input and output return losses more than 10 dB were obtained at both 2.4 and 5.2 GHz. In addition, IIP3 of 17 and 5 dBm were achieved at 2.4 and 5.2 GHz, respectively. No off‐chip components were required for input and output matching. To our knowledge, this LNA exhibits a state‐of‐the‐art performance. Due to the careful selection of the size of the transistors and the passive elements in our proposed method power matching and noise matching can be achieved simultaneously at the dual‐band of interest. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 287–292, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20280
Wideband cylindrical dielectric resonator antenna excited using an L‐strip feed
Authors: Menon Sreedevi K. , Lethakumary B. , Mohanan P. , Bijumon P. V. , Sebastian M. T.
Published: June 2004

A broadband cylindrical dielectric resonator antenna (DRA) energized with an L‐strip feed is presented. The novel exciting technique achieves a 2:1 VSWR bandwidth of 18%. The variation of bandwidth for different feed parameters is also studied. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 293–294, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20281
Nonuniform meandered and fork‐type grounded antenna design
Authors: Hsu Cho‐Kang , Chiu Cheng‐Nan
Published: June 2004

A novel kind of printed antenna, called nonuniform meandered and fork‐type grounded antenna (NMFGA), is proposed in this paper. The design of the NMFGA is simple, clear, and versatile: a nonuniform meandered patch (top patch) is designed to generate multiple and tunable resonant frequencies, while a fork‐type grounded patch (bottom patch) is designed to improve and enhance the bandwidth property. As a design example, an EGSM/DCS dual‐band antenna is presented. The measured and simulated reflection losses and measured radiation patterns are obtained and studied. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 297–299, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20284
Analysis of finite arrays of circumferentially oriented printed dipoles on electrically large cylinders
Authors: Ertürk V. B. , Güner Baris
Published: June 2004

An efficient and accurate hybrid method of moments (MoM)/Green's function technique in the spatial domain is developed for the rigorous analysis of large, finite phased arrays of circumferentially oriented printed dipoles on electrically large, dielectric‐coated, circular cylinders. Basic performance metrics (in the form of array current distribution, active reflection coefficient, far‐field patterns, and so forth) of several arrays have been obtained and compared with similar printed arrays on grounded planar substrates. Certain discrepancies have been observed and discussed. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 299–304, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20285
Quasistatic TEM characteristics of multilayer elliptical and cylindrical coplanar waveguides
Authors: Akan Volkan , Yazgan Erdem
Published: June 2004

Simple analytic CAD‐oriented expressions are presented for calculating the quasistatic TEM parameters of multilayer elliptical coplanar waveguides (ME CPWs) and multilayer cylindrical coplanar waveguides (MC CPWs) by using the conformal mapping method. It is shown that the derived expressions are accurate and very simple for use in related applications. Comparisons have also been made between the results of this paper and those available in the literature. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 317–322, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20290
Strain‐tuned dual‐wavelength erbium‐doped fiber laser
Authors: Xiong Lingyun , Sun Lei , Feng Xinhuan , Kai Guiyun , Liu Yange , Zhang Weigang , Yuan Shuzhong , Dong Xiaoyi
Published: June 2004

A tunable dual‐wavelength Er‐doped fiber laser (EDFL) is proposed and demonstrated. By applying axial and lateral strain simultaneously on the fiber Bragg grating (FBG), the absolute wavelength and wavelength spacing of the Er‐doped fiber laser can be tuned continuously. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 323–324, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20291
Design model for broadside‐coupled suspended substrate stripline for microwave and millimeter‐wave applications
Authors: Kumar Raj
Published: June 2004

Simple closed‐form expressions for the analysis of broadside coupled suspended substrate stripline is presented. The expressions are valid over a wide range of structural parameters and dielectric constants. The validity range of this expression for structural parameters is 1.0 ≤ εr ≤ 30.0 (dielectric constant), 0.2 ≤ W/b ≤ 10.0 (strip width), and d/b ≤ 0.5 (substrate thickness). The average accuracies of the present expressions are <0.8% and <0.6% for even‐ and odd‐mode impedances, respectively. The maximum deviation is ±1.25% and ±1.16% for even‐ and odd‐mode impedances with respect to the reference values. This closed‐form model is useful for the interactive CAD analysis of microwave and millimeter‐wave circuit. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 328–331, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20293
Author's reply to remarks on “A 2D TLM model for electromagnetic wave propagation in Tellegen media”
Authors: Cabeceira A. C. L. , Barba I. , Grande A. , Repressa J.
Published: June 2004

© 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 345–346, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20299
Agenesis of the ductus venosus associated with direct umbilical venous return into the heart—case series and review of literature
Authors: Sau Ashis , Sharland Gurleen , Simpson John
Published: June 2004

Objectives

The purpose of our study was to review our own experience and the available literature on the prenatal diagnosis of absent ductus venosus associated with direct insertion of the umbilical vein into the heart.

Methods

A retrospective review of the database of a tertiary fetal cardiology centre. The literature was searched for cases with a prenatal diagnosis of such an umbilical venous anomaly.

Results

Between January 2000 and June 2003, nine fetuses were diagnosed as having absence of the ductus venosus with the umbilical vein directly draining into the heart. This represents the largest reported clinical experience of this anomaly. We also report, to our knowledge, the first prenatal diagnosis of insertion of the umbilical vein into the left atrium. Combining our series with those found in the literature, a total of 35 cases were identified. Cardiomegaly was reported in 25 of the 35 cases (71%). Structural cardiac abnormalities and other extra‐cardiac anomalies were found in 13 of the 35 cases (37%). Hydrops was present or developed in 6 cases (17%). The outcome data were available for 33. The overall survival rate was 67% (22 of 33).

Conclusions

Careful assessment of the ductus venosus and the umbilical vein should be a part of the evaluation of every fetus with unexplained cardiomegaly. All fetuses with abnormal connection of the umbilical vein should undergo a clinical and ultrasonographic assessment both in utero and after birth to exclude any cardiac and extra‐cardiac abnormalities. During the prenatal period, serial ultrasound examinations are indicated and delivery is considered when there is evidence of progressive cardiovascular compromise. Copyright © 2004 John Wiley & Sons, Ltd.
Prenatally diagnosed giant omphaloceles: short‐ and long‐term outcomes
Authors: Biard Jean‐Marc , Wilson R. Douglas , Johnson Mark P. , Hedrick Holly L. , Schwarz Uwe , Flake Alan W. , Crombleholme Timothy M. , Adzick N. Scott
Published: June 2004

Objectives

To review prenatal findings, short‐ and long‐term outcomes of giant omphaloceles (GO) managed at a single institution (1996–2001).

Methods

Prenatal findings and early postnatal outcomes were retrospectively reviewed. Clinical short‐ and long‐term outcomes were analyzed in eight and five children respectively. Parents and physicians of the children were surveyed by written questionnaires about the children's subsequent health issues. (IRB 2002‐2‐2683).

Results

Seventeen pregnancies with GO were identified: Eight fetuses were live born, four ended in (terminations), two died in utero and three were lost to follow‐up. Live‐born fetuses had prenatal ascites, extreme levocardia and were delivered by cesarean section at a mean of 37 weeks' gestation with a mean birth weight of 2903 g. All neonates required intubation. Two infants (2/8) died within one year. Four of the six survivors had respiratory insufficiency with a mean ventilation time of 76 days. Respiratory and feeding problems complicated the early neonatal course. Long‐term follow‐up was available for five patients (mean age of 33.2 months). Asthma, recurrent pulmonary infections, feeding problems, gastroesophageal reflux and failure to thrive were the major problems.

Conclusions

Respiratory and feeding problems were the most common neonatal and long‐term medical management issues. Parents need to be counseled prenatally about the probability of multiple surgeries and long hospitalization following birth. Copyright © 2004 John Wiley & Sons, Ltd.
Photocrosslinking system using multifunctional epoxy crosslinkers having thermally degradable properties
Authors: Okamura Haruyuki , Shin Kazuo , Tsunooka Masahiro , Shirai Masamitsu
Published: June 2004

A novel thermally degradable photocrosslinking system was investigated. Difunctional and trifunctional epoxides with tertiary ester linkages were synthesized. When blended films of epoxides and poly(vinyl phenol) or epoxides and poly(methacrylic acid‐co‐ethyl methacrylate) with a photoacid generator were irradiated and then baked at relatively low temperatures (<100 °C), the films became insoluble in solvents. The heating conditions strongly affected the insoluble fractions of the blends. The insoluble fractions of the blended films containing the trifunctional epoxide were higher than the fractions of the films containing the difunctional epoxide. The crosslinked films became soluble after baking at relatively high temperatures (>120 °C). The reaction pathway of the blended system was studied with in situ Fourier transform infrared measurements. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3685–3696, 2004
Preparation and properties of alkoxy(methyl)silsesquioxanes as coating agents
Authors: Gunji Takahiro , Iizuka Yasuhito , Arimitsu Koji , Abe Yoshimoto
Published: June 2004

Polysilsesquioxanes were prepared through the acid‐catalyzed hydrolytic polycondensation of triethoxy(methyl)silane, triisopropoxy(methyl)silane, or triisobutoxy(methyl)silane and subjected to dip coating to form coating films. The film formation depended on the polarity and crystallinity of the substrate, and a correlation was found between the substrate and polysilsesquioxane solubility parameters. When the coating film was heated, thermal condensation occurred at about 500 °C between hydroxy groups or between hydroxy and alkoxy groups. The methyl group attached to silicon decomposed, and siloxane bonding formed at about 800 °C. The adhesion and hardness of the coating films were evaluated with the Japanese Industrial Standard K5400 protocol, and they increased with increases in the heating time and heat‐treatment temperature. The refractive index of the coating films decreased when the heat‐treatment temperature was increased to 500 °C because of the combustion of organic groups. In contrast, the surface electric resistance increased with the heat‐treatment temperature up to 500 °C. The dielectric constant was 2.6–2.8 and decreased with an increases in the molecular weight and the degree of crosslinking of the polysilsesquioxanes. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3676–3684, 2004
Dielectric analysis of a crosslinking epoxy resin at a high microwave frequency
Authors: Zong Liming , Zhou Shuangjie , Sun Rensheng , Kempel Leo C. , Hawley Martin C.
Published: June 2004

The dielectric properties of a curing epoxy/amine system have been studied from 25 to 120 °C at 2.45 GHz. The epoxy resins at different extents of curing exhibit a γ relaxation, which can be described by the Arrhenius rate law. The relaxation is attributed to the motions of the dipolar groups associated with the crosslinking system. A simple model is proposed to represent the temperature dependence of the dielectric properties. A complete description of the evolution of the parameters during the polymerization has been obtained. The nature of the information yielded by dielectrometry on the dynamics of the system is discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2871–2877, 2004
An Overview on the Synthetic Routes and Properties of Ammonium Dinitramide (ADN) and other Dinitramide Salts
Authors: Venkatachalam Subbiah , Santhosh Gopalakrishnan , Ninan Ninan Kovoor
Published: June 2004

In recent years, there has been a considerable interest in the development of novel type of high performance propellants for use in solid rocket motors. Ammonium salt of dinitramidic acid NH4N(NO2)2 (ADN) has attracted wide interest as a potentially useful energetic oxidizer for rocket propellants because of its clean and environment‐friendly exhaust products during burning. ADN contains one N(NO2)2 group and its synthesis requires new type of N‐nitration. The present paper reviews the general synthetic methods used for the synthesis of inorganic, organic and metal dinitramide salts and their properties, with a special emphasis on ammonium dinitramide. The salient features with reference to the extent of conversion and ease of separation of the products of the various synthetic methodologies are also addressed.
Optimization of Propellant Binders – Part I: Statistical Methodology
Authors: Niehaus Michael , Greeb Olaf
Published: June 2004

The development of new propellant binder systems requires the thermodynamic calculation of physico‐chemical data as well as the adaption of the mechanical properties in order to achieve a reliable innerballistic profile of the resulting propellant. However, in most cases the mechanical data may not be easily predicted due to the complex interactions between the components of the binder like the resin, the curing agent or possibly plasticizers and curing catalysts. Therefore, this study focusses on the capability of the multivariate analysis on the prediction of the E‐modulus of a system comprising nitrocellulose as well as GAP, Desmodur N100 and an energetic plasticiser. Using this method, an equation has been derived which, within the regression intervall, may be used for the prediction of the E‐modulus as a function of the components mentioned above.
Patterns of retinal light absorption related to retinitis pigmentosa mutants from in silico model structures of rhodopsin
Authors: Padrón‐García J. Alexander , Crespo‐Otero Rachel , Hernández‐Rodríguez Erix William , Garriga Pere , Montero Luis A. , García‐Piñeiro José Carlos
Published: June 2004

Changes induced by mutations in rhodopsin that are associated with the degenerative visual disease retinitis pigmentosa result in an altered pattern of light absorption according to quantum mechanical simulations and reference experimental works. Eleven single‐point mutations associated with retinitis pigmentosa at and in the proximity to the retinal binding pocket of rhodopsin have been modeled in silico and their spectra calculated with the NDOL (Neglect of Differential Overlap accounting L azimuthal quantum number) a priori method. The altered pattern of absorption found would lead to cumulative consequences in energy dissipation with aging. Different energy balances in the case of mutants at the very molecular level, compared to native nonmutated rhodopsin, can cause permanent cellular stress and would play a role in the progression of the retine degenerative process. It could explain the worsening of the pathological condition mostly in adults and suggests the probable beneficial effects of using quenching drugs and protection devices against excess of light in the early stages of life for avoiding or reducing potential damage. Proteins 2004. © 2004 Wiley‐Liss, Inc.
Reversal of the inhibition of photosynthesis by herbicides affecting hydroxyphenylpyruvate dioxygenase by plastoquinone and tocopheryl derivatives inChlamydomonas reinhardtii
Authors: Trebst Achim , Depka Brigitte , Jäger Johannes , Oettmeier Walter
Published: June 2004

Isoxaflutole or pyrazolate inhibition of tocopherol and plastoquinone biosynthesis in the green algaChlamydomonas reinhardtiiDang leads to the inactivation of photosystem II and the degradation of its reaction centre D1 protein when exposed to strong light. Cell‐permeable short‐chain derivatives of plastoquinone and tocopherol were tested in the reversal. Addition of decyl‐plastoquinone reverses herbicide‐induced inhibition of photosynthesis and inactivation of photosystem II in short‐time (1 h) exposure of the algae to high light. In high light longer than 1 h, decyl‐plastoquinone alone loses effectiveness, but a synthetic permeable tocopheryl derivative retards the inhibitory effects on photosystem II and on the degradation of the D1 protein. This indicates that tocopherol deficiency induced by the herbicides makes a major contribution to their secondary mode of action in high light stress. Copyright © 2004 Society of Chemical Industry
Changes in susceptibility to conventional insecticides of a Cry1Ac‐selected population of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)
Authors: Wu Kongming , Guo Yuyuan
Published: June 2004

The changes in the susceptibility of the cotton bollworm, Helicoverpa armigera (Hübner) to three insecticides (lambda‐cyhalothrin, phoxim and endosulfan) commonly used for control of this pest in China were monitored by bioassays at various generations. The insects were originally collected from Bt cotton fields and selected with Cry1Ac over 44 generations. In comparison with a susceptible strain, the larval resistance of the Bt‐selected populations to Cry1Ac toxin increased 106‐fold. Simultaneously, the resistance levels to lambda‐cyhalothrin, phoxim and endosulfan declined dramatically. The results indicated no positive cross‐resistance between Cry1Ac toxin and the insecticides. Evidence of the lack of cross‐resistance to three commonly used synthetic insecticides in our laboratory‐derived Cry1Ac‐resistant population may suggest that growers can confidently use these insecticides if and when resistance to Cry1Ac cotton does occur. Copyright © 2004 Society of Chemical Industry
Design Strategies for the Multivariate Exponentially Weighted Moving Average Control Chart
Authors: Testik Murat Caner , Borror Connie M.
Published: June 2004

The multivariate exponentially weighted moving average (MEWMA) control chart has received significant attention from researchers and practitioners because of its desirable properties. There are several different approaches to the design of MEWMA control charts: statistical design; economic–statistical design; and robust design. In this paper a review and comparison of these design strategies is provided.Copyright © 2004 John Wiley & Sons, Ltd.
Statistical Inference about the Shape Parameter of the New Two‐parameter Bathtub‐shaped Lifetime Distribution
Authors: Wu Jong‐Wuu , Lu Hai‐Lin , Chen Chong‐Hong , Wu Chun‐Hsien
Published: June 2004

This paper proposes a simple and exact method for conducting a statistical test about the shape parameter of the new two‐parameter lifetime distribution with a bathtub‐shaped or increasing failure rate function, as well as an exact confidence interval for the same parameter. The necessary critical values of the test are given. The method provided in this paper can be used for type II right censored data. Moreover, Monte Carlo simulation and an example are used to compare this new method to the existing approach of Chen (Statistics and Probability Letters 2000; 49:155–161). Copyright © 2004 John Wiley & Sons, Ltd.
Gender and ethnicity differences in the prevalence of traumatic events: evidence from a New Zealand community sample
Authors: Flett Ross A. , Kazantzis Nikolaos , Long Nigel R. , MacDonald Carol , Millar Michelle
Published: June 2004

One thousand five hundred community residing New Zealand adults were assessed regarding their experience of traumatic events. Sixty‐one per cent of those surveyed reported exposure to a traumatic event during their lifetime. Unexpected death of a close friend or relative was the most prevalent traumatic experience for the present sample, whereas combat and natural disasters were the least prevalent traumatic events. Consistent with prior research demonstrating gender differences in exposure to traumatic events, child and adult sexual assault was more common among women, and motor vehicle accidents and combat were more common among men. The present study also found that Maori individuals (indigenous people) had experienced a number of traumatic events to a greater extent than their European counterparts. These results are discussed within the New Zealand social context. Copyright © 2004 John Wiley & Sons, Ltd.
A distant evolutionary relationship between GPI‐specific phospholipase D and bacterial phosphatidylcholine‐preferring phospholipase C
Authors: Rigden Daniel J
Published: June 2004

In eukaryotes some surface proteins are attached to the plasma membrane by a glycosylphosphatidylinositol (GPI) anchor. A GPI‐specific phospholipase D (GPI‐PLD) activity has been characterized and implicated in the regulation of anchoring, thereby influencing the dispersal of anchored proteins or their maintenance on the cell surface, and possibly in cell signalling. Despite its biological and medical importance, little is known of the structure of GPI‐PLD. Here, a distant relationship between the catalytic domains of GPI‐PLD and some bacterial phospholipases C is demonstrated. A model of the GPI‐PLD catalytic site sheds light on catalysis and highlights possibilities for design of improved and more specific GPI‐PLD inhibitors. The databases contain hitherto unnoticed close homologues of GPI‐PLD from yeast and Dictyostelium discoideum.
Lipopolysaccharide signaling induces serum amyloid A (SAA) synthesis in human hepatocytes in vitro
Authors: Migita Kiyoshi , Abiru Seigo , Nakamura Minoru , Komori Atsumasa , Yoshida Yuki , Yokoyama Terufumi , Daikoku Manabu , Ueki Toshihito , Takii Yasushi , Yano Koji , Yastuhashi Hiroshi , Eguchi Katsumi , Ishibashi Hiromi
Published: June 2004

To investigate the role of lipopolysaccharide (LPS) in hepatocyte activation, we examined the expression of Toll‐like receptor 4 (TLR4), the putative receptor for LPS in human hepatocytes. TLR4 mRNA and protein expression was confirmed in human hepatocytes. Stimulation of human hepatocytes with LPS results in rapid degradation of IkappaB‐α and mitogen activated protein kinase activation. Human hepatocytes stimulated by LPS produced serum amyloid A protein. Our data suggest that human hepatocytes utilize components of TLR4 signal transduction pathways in response to LPS and these direct LPS‐mediated effects on hepatocytes may contribute to liver inflammation and injury.
Vitamin E activates CRABP‐II gene expression in cultured human fibroblasts, role of protein kinase C
Authors: Gimeno Amparo , Zaragozá Rosa , Viña Juan R , Miralles Vicente J
Published: June 2004

The treatment of human fibroblasts with different tocopherols in the presence of retinol caused an increase in cytoplasmic retinoic acid binding protein II (CRABP‐II) mRNA and protein. The possibility of an involvement of protein kinase C (PKC) in the response to tocopherols was supported by the results obtained with the PKC‐specific inhibitors, calphostin C and bisindolylmaleimide I. The effect of α‐tocopherol was prevented by okadaic acid, suggesting that a protein phosphatase is responsible for PKC dephosphorylation produced by the presence of tocopherols. The results shown support the hypothesis that phosphorylation/dephosphorylation of RXRα via PKC may be involved in the regulation of CRABP‐II gene expression.
Sphingolipid C4 hydroxylation influences properties of yeast detergent‐insoluble glycolipid‐enriched membranes
Authors: Idkowiak-Baldys Jolanta , Grilley Michelle M , Takemoto Jon Y
Published: June 2004

Sphingoid base C4 hydroxylation is required for syringomycin E action on the yeast plasma membrane. Detergent‐insoluble glycolipid‐enriched membranes (DIGs) from a yeast strain lacking C4 hydroxylated sphingoid bases (sur2
Δ) are composed of linear membrane fragments instead of vesicular structures observed for wild‐type DIGs, though they have similar lipid compositions and amounts of DIG marker proteins. Light‐scattering bands collected from sur2
Δ after centrifugation of Triton X‐100‐treated cell lysates in continuous density gradients have lower buoyant densities than that of the wild‐type. The results show that C4 hydroxylation influences the physical and structural properties of DIGs and suggest that syringomycin E interacts with lipid rafts.
Distinct regulatory mechanism of yeast GPX2 encoding phospholipid hydroperoxide glutathione peroxidase by oxidative stress and a calcineurin/Crz1‐mediated Ca2+ signaling pathway
Authors: Tsuzi Daisuke , Maeta Kazuhiro , Takatsume Yoshifumi , Izawa Shingo , Inoue Yoshiharu
Published: June 2004

The GPX2 gene encodes a homologue of mammalian phospholipid hydroperoxide glutathione peroxidase in Saccharomyces cerevisiae. Previously, we have reported that the oxidative stress‐induced expression of GPX2 is strictly regulated by Yap1 and Skn7 transcription factors. Here, we found that the expression of GPX2 is induced by CaCl2 in a calcineurin (CN)/Crz1‐dependent manner, and the CN‐dependent response element was specified in the GPX2 promoter. Neither Yap1 nor Skn7 was required for Ca2+‐dependent induction of GPX2, therefore, distinct regulation for the oxidative stress response and Ca2+ signal response for GPX2 exists in yeast cells.
Increase of SUMO‐1 expression in response to hypoxia: direct interaction with HIF‐1α in adult mouse brain and heart in vivo
Authors: Shao Ruijin , Zhang Fu-Ping , Tian Fei , Anders Friberg P , Wang Xiaoyang , Sjöland Helen , Billig Håkan
Published: June 2004

The present study investigates the regulation of small ubiquitin‐related modifier‐1 (SUMO‐1) expression in response to hypoxia in adult mouse brain and heart. We observed a significant increase in SUMO‐1 mRNAs and proteins after hypoxic stimulation in vivo. Because SUMO‐1 interacts with various transcription factors, including hypoxia‐inducible factor‐1β (HIF‐1β) in vitro, we not only demonstrated that the HIF‐1α expression is increased by hypoxia in brain and heart, but also provided evidence that SUMO‐1 co‐localizes in vivo with HIF‐1α in response to hypoxia by demonstrating the co‐expression of these two proteins in neurons and cardiomyocytes. The specific interaction between SUMO‐1 and HIF‐1α was additionally demonstrated with co‐immunoprecipitation. These results indicate that the increased levels of SUMO‐1 participate in the modulation of HIF‐1α function through sumoylation in brain and heart.
The phosphorylation status and anti‐apoptotic activity of Bcl‐2 are regulated by ERK and protein phosphatase 2A on the mitochondria
Authors: Tamura Yuki , Simizu Siro , Osada Hiroyuki
Published: June 2004

Bcl‐2 protein play important roles in the regulation of apoptosis. We previously reported that the phosphorylation of Bcl‐2 was augmented by treatment with protein phosphatase 2A (PP2A) inhibitor; however, the kinase responsible for Bcl‐2 phosphorylation had not yet been identified. In this study, we identified extracellular‐signal‐regulated kinase (ERK) as the responsible kinase for the phosphorylation of Bcl‐2. We also found that the transmembrane region (TM) deleted form of Bcl‐2 (Bcl‐2ΔTM), which was unable to localize on the mitochondria was constitutively phosphorylated, whereas wild‐type Bcl‐2 that localized on the mitochondria, was present in its hypophosphorylated form. The phosphorylation of Bcl‐2ΔTM was retarded by treatment with MAP kinase ERK kinase (MEK) inhibitor and PP2A did not bind to Bcl‐2ΔTM. These observations suggest that Bcl‐2ΔTM is constitutively phosphorylated by ERK, but is not dephosphorylated by PP2A in human tumor cell lines. The phosphorylation of Bcl‐2 resulted in a reduction in anti‐apoptotic function, implying that dephosphorylation promoted the anti‐apoptotic activity of Bcl‐2 protein in human tumor cell lines. Thus, the present findings suggest that ERK and PP2A are physiological regulators of Bcl‐2 phosphorylation, and these enzymes exert an influence on the anti‐apoptotic function of Bcl‐2.
Induction of the glucose‐6‐phosphate dehydrogenase gene expression by chronic hypoxia in PC12 cells
Authors: Gao Lin , Mejı́as Rebeca , Echevarrı́a Miriam , López-Barneo José
Published: June 2004

We studied the regulation of glucose‐6‐phosphate dehydrogenase (G6PD) gene expression by chronic hypoxia. G6PD mRNA level and activity were increased in PC12 cells by hypoxia in a dose‐ and time‐dependent manner. Cobalt chloride and dimethyloxalylglycine, which can mimic hypoxia, also activated G6PD gene expression. Interestingly, hypoxia‐induced G6PD expression followed a time course much slower than that of phosphoglycerate kinase 1 (PGK1), a hypoxia‐inducible factor (HIF)‐dependent glycolytic enzyme. Hypoxic‐G6PD induction was almost negligible in non‐excitable Buffalo rat liver cells, although in these cells PGK1 was strongly upregulated by low PO2. Furthermore, G6PD but not PGK1 induction was blocked by the antioxidants glutathione and N‐acetylcysteine. These results suggest the dependence of G6PD gene expression on HIF and intracellular redox status and the differential hypoxic regulation of glucose‐metabolizing enzymes.
Roles of a conserved proline in the internal fusion peptide of Ebola glycoprotein
Authors: Gómara Marı́a J , Mora Puig , Mingarro Ismael , Nieva José L
Published: June 2004

The structural determinants underlying the functionality of viral internal fusion peptides (IFPs) are not well understood. We have compared EBOwt (GAAIGLAWIPYFGPAAE), representing the IFP of the Ebola fusion protein GP, and EBOmut (GAAIGLAWIPYFGRAAE) derived from a non‐functional mutant with conserved Pro537 substituted by Arg. P537R substitution did not abrogate peptide‐membrane association, but interfered with the ability to induce bilayer destabilization. Structural determinations suggest that Pro537 is required to preserve a membrane‐perturbing local conformation in apolar environments.
Expression of brain‐specific angiogenesis inhibitor 3 (BAI3) in normal brain and implications for BAI3 in ischemia‐induced brain angiogenesis and malignant glioma
Authors: Kee Hae Jin , Ahn Kyu Youn , Choi Ki Choon , Won Song Jung , Heo Tag , Jung Shin , Kim Jong-Keun , Bae Choon Sang , Kim Kyung Keun
Published: June 2004

Murine brain‐specific angiogenesis inhibitor 1 and 2 (mBAI1, mBAI2) are involved in angiogenesis after cerebral ischemia. In this study, mBAI3 was cloned and characterized. Northern and Western blot analyses demonstrated a unique developmental expression pattern in the brain. The level of mBAI3 in brain peaked 1 day after birth, unlike mBAI1 and mBAI2, which peaked 10 days after birth. In situ hybridization analyses of the brain showed the same localization of BAI3 as BAI1 and BAI2, which includes most neurons of cerebral cortex and hippocampus. In the in vivo focal cerebral ischemia model, BAI3 expression decreased from 0.5 h after hypoxia until 8 h, but returned to control level after 24 h. The expression of vascular endothelial growth factor following ischemia showed an inverse pattern. The decreased expressions of BAIs in high‐grade gliomas were observed, but BAI3 expression was generally lower in malignant gliomas than in normal brain. Our results indicate that the expression and distribution of BAI3 in normal brain, but not its developmental expression, are very similar to those of BAI1 and BAI2, and that BAI3 may participate in the early phases of ischemia‐induced brain angiogenesis and in brain tumor progression.
Evaluation of the mechanism underlying the inhibitory effect of guanidinoacetate on brain Na+, K+‐ATPase activity
Authors: Zugno Alexandra I. , Franzon Renata , Chiarani Fábria , Bavaresco Caren S. , Wannmacher Clovis M.D. , Wajner Moacir , Wyse Angela T.S.
Published: June 2004

Guanidinoacetate methyltransferase deficiency (GAMT‐deficiency) is an inherited neurometabolic disorder clinically characterized by epilepsy and mental retardation and biochemically by accumulation of guanidinoacetate (GAA) and depletion of creatine. Although the neurological symptoms are predominant, the pathogenesis of the brain dysfunction in this disorder is not yet established. In the present study we investigated the in vitro effect of GAA on Na+, K+‐ATPase and Mg2+‐ATPase activities in synaptic plasma membrane from hippocampus of young rats. Results showed that GAA significantly inhibited Na+, K+‐ATPase activity without affecting Mg2+‐ATPase activity. We also evaluated the effect of glutathione (GSH), trolox, Nϖ‐nitro‐l‐arginine methyl ester (L‐NAME) and taurine (Tau) on the inhibition elicited by GAA on Na+, K+‐ATPase activity. GSH, trolox, L‐NAME and Tau per se did not alter Na+, K+‐ATPase activity. However, L‐NAME and taurine prevented the inhibitory effect of GAA on this enzyme activity. Our findings suggest that the inhibition of Na+, K+‐ATPase activity caused by GAA is possibly mediated by nitric oxide (NO) formation and/or synaptic membrane alteration. The present data may contribute to the understanding of the neurological dysfunction characteristic of GAMT‐deficient patients.
Recruitment on the Net: How Do Organizational Web Site Characteristics Influence
Authors: Cober Richard T. , Brown Douglas J. , Keeping Lisa M. , Levy Paul E.
Published: June 2004

The use of organizational web sites for recruitment has become increasingly common. Despite their widespread growth, however, little is known about how these web sites influence recruitment outcomes. In the current paper, we present a model that explicates how job seekers interact with and respond to web site characteristics to predict various job seeker attitudes and behaviors. We suggest that job seekers are initially affected by the facade of a web site, comprised of the web site’s aesthetic and playfulness features. Coupled with system features of the web site, these initial affective reactions then influence perceptions of the usability of the web site. Perceptions of usability and affective reactions work through two key mediating constructs, job seeker search behavior and web site attitude, to ultimately predict applicant attraction. Throughout the paper we present a series of testable propositions that should serve to guide future research.
A Person-Environment Fit Model for Virtual Organizations
Authors: Shin Yuhyung
Published: June 2004

While the increasing sophistication of information technology has led to the spread of virtual organizations, there has been very little research on what factors contribute to individuals’ effectiveness in such organizations. This paper argues that organizations possess different degrees of virtuality based on four dimensions of temporal, spatial, cultural, and organizational dispersion. Using a person-environment fit framework, a theoretical model that identifies individual qualities required to fit into virtual organizations, virtual teams, and virtual jobs is developed, taking into account dimensions and degrees of virtuality. Mechanisms for enhancing fit in virtual organizations as well as theoretical and practical implications of the model are addressed.
Eight Motivational Forces and Voluntary Turnover: A Theoretical Synthesis with Implications for Research
Authors: Maertz Carl P. , Griffeth Rodger W.
Published: June 2004

In this study, we synthesize, from the attitude and turnover literatures, a framework of eight (8) distinctive motives, or “Forces”. We then illustrate how the “8 Forces” framework can be utilized by turnover researchers as clarification of reported reasons for turnover, as causal mediators of turnover predictors, and as factors related to the type of turnover decision process. Finally, we discuss further implications of this framework.
Signaling the Strategic Value of Knowledge
Authors: Ndofor Hermann Achidi , Levitas Edward
Published: June 2004

Firms competing primarily on knowledge resources face problems in informing relevant external stakeholders about the value of that knowledge without losing its value. This knowledge may be transferred to stakeholders only at great expense, or that transfer of knowledge to stakeholders may simultaneously promote its transfer to competitors. By conceptualizing firms and the environments within which they compete to differ in levels of uncertainty, this paper develops a framework to examine signaling mechanisms firms can use to effectively signal the value of their knowledge to two key stakeholder groups, the capital and labor markets, while avoiding associated transfer problems.
THE ACADEMIC BETRAYAL OF FREE SPEECH
Authors: Jacobson Daniel
Published: June 2004

“ 'Free speech' is just the name we give
to verbal behavior that serves the substantive agendas we wish
to advance”—or so literary theorist and professor of law
Stanley Fish has claimed. This cynical dictum is one of several
skeptical challenges to freedom of speech that have been extremely
influential in the American academy. I will follow the skeptics'
lead by distinguishing between two broad styles of critique: the
progressive and the postmodern. Fish's dictum, however, like many
of the bluntest charges, belongs to neither class exclusively. As an
initial characterization of the distinction between these critiques,
progressive skepticism claims that freedom of speech is a bad thing,
while postmodernist skepticism claims it to be conceptually impossible.
Both forms of skepticism hold the classical liberal endorsement of free
speech and condemnation of censorship to be both naive and reactionary.
Skepticism about free speech flourishes at universities in the United
States and is especially well represented among professors at the
country's most prestigious law schools. As legal scholar Robert
Post approvingly observes: “Liberated from traditional
inhibitions against official suppression of speech, the left has
mobilized to pursue a rich variety of political agendas.”
Partitioning net ecosystem carbon exchange into net assimilation and respiration with canopy‐scale isotopic measurements: An error propagation analysis with 13CO2 and CO18O data
Authors: Ogée J. , Peylin P. , Cuntz M. , Bariac T. , Brunet Y. , Berbigier P. , Richard P. , Ciais P.
Published: June 2004

Stable CO2 isotope measurements are increasingly used to partition the net CO2 exchange between terrestrial ecosystems and the atmosphere in terms of nonfoliar respiration (FR) and net photosynthesis (FA) in order to better understand the variations of this exchange. However, the accuracy of the partitioning strongly depends on the isotopic disequilibrium between these two gross fluxes, and a rigorous estimation of the errors on FA and FR is needed. In this study, we account for and propagate uncertainties on all terms in the mass balance and isotopic mass balance equations for CO2 in order to get accurate estimates of the errors on FA and FR. We apply our method to a maritime pine forest in the southwest of France. Nighttime Keeling plots are used to estimate the 13C and 18O isotopic signature of FR (δR), and for both isotopes the a priori uncertainty associated with this term is estimated to be around 2‰ at our site. Using δ13C‐CO2 and [CO2] measurements, we then show that the uncertainty on instantaneous values of FA and FR can be as large as 4 μmol m−2 s−1. Even if we could get more accurate estimates of the net CO2 flux, the isoflux, and the isotopic signatures of FA and FR, this uncertainty would not be significantly reduced because the isotopic disequilibrium between FA and FR is too small, around 2–3‰. With δ18O‐CO2 and [CO2] measurements the uncertainty associated with the gross fluxes lies also around 4 μmol m−2 s−1 but could be dramatically reduced if we were able to get more accurate estimates of the CO18O isoflux and the associated discrimination during photosynthesis. This is because the isotopic disequilibrium between FA and FR is large, of the order of 12–17‰. The isotopic disequilibrium between FA and FR and the uncertainty on δR vary among ecosystems and over the year. Our approach should help to choose the best strategy to study the carbon budget of a given ecosystem using stable isotopes.
Toward modeling turbulent suspension of sand in the nearshore
Authors: Hsu Tian‐Jian , Liu Philip L.‐F.
Published: June 2004

We present two depth‐ and phase‐resolving models, based on single‐ and two‐phase approaches for suspended sediment transport under water waves. Both models are the extension of a wave hydrodynamic model Cornell Breaking Wave and Structure (COBRAS). In the two‐phase approach, dilute two‐phase mass and momentum equations are calculated along with a fluid turbulence closure based on balance equations for the fluid turbulence kinetic energy kf and its dissipation rate εf. In the single‐phase approach the fluid flow is described by the Reynolds‐Averaged Navier‐Stokes equations, while the sediment concentration is calculated by an advection‐diffusion equation for the conservation of sediment mass. The fluid turbulence is calculated by kf‐εf equations that incorporate the essential influence of sediment, which can also be consistently deduced from the two‐phase theory. By adopting a commonly used sediment flux boundary condition near the bed the proposed models are tested against laboratory measurements of suspended sediment under nonbreaking skewed water waves and shoaling broken waves. Although the models predict wave‐averaged sediment concentrations reasonably well, the corresponding time histories of instantaneous sediment concentration are less accurate. We demonstrate that this is due to the uncertainties in the near‐bed sediment boundary conditions. In addition, we show that under breaking waves the near‐bed sediment pickup cannot be solely parameterized by the bottom friction, suggesting that other effects may also influence the near‐bed sediment boundary conditions.
A mechanistic model for river incision into bedrock by saltating bed load
Authors: Sklar Leonard S. , Dietrich William E.
Published: June 2004

Abrasion by bed load is a ubiquitous and sometimes dominant erosional mechanism for fluvial incision into bedrock. Here we develop a model for bedrock abrasion by saltating bed load wherein the wear rate depends linearly on the flux of impact kinetic energy normal to the bed and on the fraction of the bed that is not armored by transient deposits of alluvium. We assume that the extent of alluvial bed cover depends on the ratio of coarse sediment supply to bed load transport capacity. Particle impact velocity and impact frequency depend on saltation trajectories, which can be predicted using empirical functions of excess shear stress. The model predicts a nonlinear dependence of bedrock abrasion rate on both sediment supply and transport capacity. Maximum wear rates occur at moderate relative supply rates due to the tradeoff between the availability of abrasive tools and the partial alluviation of the bedrock bed. Maximum wear rates also occur at intermediate levels of excess shear stress due to the reduction in impact frequency as grain motion approaches the threshold of suspension. Measurements of bedrock wear in a laboratory abrasion mill agree well with model predictions and allow calibration of the one free model parameter, which relates rock strength to rock resistance to abrasive wear. The model results suggest that grain size and sediment supply are fundamental controls on bedrock incision rates, not only by bed load abrasion but also by all other mechanisms that require bedrock to be exposed in the channel bed.
Integrated hydrogeological and geophysical study of depression‐focused groundwater recharge in the Canadian prairies
Authors: Berthold Susann , Bentley Laurence R. , Hayashi Masaki
Published: June 2004

In the northern prairie region of North America, numerous seasonal wetlands and ephemeral ponds form as snowmelt water is trapped in small topographical depressions. A detailed hydrogeological investigation is combined with electrical resistivity imaging (ERI) to evaluate the roles of the wetlands and ponds on depression‐focused groundwater recharge at the St. Denis National Wildlife Area in Saskatchewan, Canada. The analysis of groundwater samples indicated two distinct geochemical zones: a zone of salt leaching under Wetland 109 and zones of salt accumulation under the adjacent uplands. Two intermediate zones were identified as partially leached or mixed leached‐unleached and premodern or mixed saline‐nonsaline water. The resistivity images of the areas around 109 were classified using the correlation between ERI‐derived electrical conductivity (EC) and the groundwater EC. The ERI data clearly showed that depression‐focused recharge occurs under all depressions regardless of size. Leaching is observed to the depth of a regional intertill aquifer, indicating that depression‐focused recharge contributes to the regional groundwater system. The ERI data also revealed the complex pattern of salt distribution that could not have been recognized by hydrogeological observations alone. The complex distribution of salts appears to be caused by interaction between wetlands and variations in topography.
First principles determination of the phase boundaries of high‐pressure polymorphs of silica
Authors: Tsuchiya Taku , Caracas Razvan , Tsuchiya Jun
Published: June 2004

We perform first principles calculations of three ordered high‐pressure polymorphs of silica to investigate their phase equilibrium: stishovite, CaCl2 and α‐PbO2. We use the density‐functional linear response theory to calculate lattice dynamical properties and the quasiharmonic approximation to determine the high temperature phase boundaries. We obtain positive and almost parallel Clapeyron slopes for both the stishovite‐CaCl2 and the CaCl2‐α‐PbO2 phase transitions: 56 + 0.006 T (GPa) and 106 + 0.006 T (GPa), respectively. These boundaries are consistent with recent experimental results. The pressure and temperature conditions for the former transition correspond to the mid‐lower mantle region where some minor seismic discontinuities have been observed. The latter transition corresponds to the pressure and temperature conditions associated with the lowermost mantle and the D″ discontinuity. The stable form of silica at the bottom of mantle is the α‐PbO2 structure.