bluuebunny/crossref_metadata_2025 huggingface dataset:
Cross Metathesis Allowing the Conversion of a Ruthenium Indenylidene Complex into Grubbs' Catalyst
Authors: Dorta Reto , Kelly Roy A. , Nolan Steven P.
Published: August 2004

The active metathesis catalyst (PCy3)2Cl2Ru(3‐phenylinden‐1‐ylidene) (4) was obtained in high yield using a simple one‐pot procedure. The initial reaction of RuCl2(PPh3)3 with 1,1‐diphenyl‐2‐propyn‐1‐ol gave (PPh3)2Cl2Ru(3‐phenylinden‐1‐ylidene) (6). In situ exchange of PPh3 with PCy3 led to the isolation of 4 in>90% yield. Whereas complex 6 did not show any activity in the cross metathesis reaction with styrene, reaction of compound 4 with excess styrene gave Grubbs' catalyst, (PCy3)2Cl2RuC(H)Ph (1), dichloro(phenylmethylene)bis(tricyclohexylphosphane)ruthenium(II), in nearly quantitative yield. This two‐step procedure yielded complex 1 in 88% overall yield starting from inexpensive and commercially available materials. The widely used metathesis catalyst 1 was also obtained in good yield in one single step, that is, without isolation of compound 4, making this a simple and safe synthetic route to Grubbs' catalyst.
Enantioselective Hydrogenation of Trimethylindolenine in Ionic Liquids
Authors: Giernoth Ralf , Krumm Matthias S.
Published: August 2004

The enantioselective hydrogenation of trimethylindolenine (1) has been carried out in a variety of ionic liquids using an Ir‐XYLIPHOS catalyst. Compared to the reaction in conventional organic media, slightly higher temperatures (50 °C) are required, which is mainly due to the higher viscosities of the ionic media. Under these conditions we were able to identify three reaction media that gave ees comparable to the conventional process in toluene with greatly reduced reaction time (15 h as opposed to 23 h for 100% conversion; 91% conversion after 8 h). The sensitivity of the reaction system towards oxygen was also reduced significantly.
Chiral Amplification in Macromolecular Helicity Assisted by Noncovalent Interaction with Achiral Amines and Memory of the Helical Chirality
Authors: Morino Kazuhide , Watase Nobuyuki , Maeda Katsuhiro , Yashima Eiji
Published: August 2004

Poly[(4‐carboxyphenyl)acetylene] (poly‐1) exhibits an intense induced circular dichroism (ICD) in the UV‐visible region upon complexation with excess (R)‐1‐(1‐naphthyl)ethylamine ((R)‐2), owing to the formation of a predominantly single‐handed helical conformation of the polymer backbone. In the presence of a small amount of (R)‐2, poly‐1 showed a very weak ICD due to the lack of a single‐handed helical conformation. However, we have found that the co‐addition of the excess bulky, achiral 1‐naphthylmethylamine (5) with a small amount of (R)‐2 caused a dramatic increase in the ICD magnitude, comparable to the full ICD induced by excess (R)‐2. This indicates that an almost single‐handed helix can be induced on poly‐1 upon complexation with a small amount of (R)‐2 assisted by achiral 5. Furthermore, the induced single‐handed helical poly‐1 could be successfully memorized by the replacement of (R)‐2 and 5 with achiral 2‐aminoethanol or n‐butylamine.
Extracellular matrix regulates endothelial functions through interaction of VEGFR‐3 and integrin α5β1
Authors: Zhang Xuefeng , Groopman Jerome E. , Wang Jian Feng
Published: August 2004

Endothelium extracellular matrix (ECM) interactions can provide distinct spatial and molecular signals which control cellular proliferation, migration, and differentiation. Here, we investigated the role of fibronectin (FN), a major ECM protein, on the functions of lymphatic endothelial cells (LEC). We observed that FN, the ligand for integrin α5β1, selectively promoted the growth of LEC as compared with vitronectin (VN) in the presence of the ligand for vascular endothelial growth factor receptor 3 [VEGFR‐3 (VEGF‐C156S)]. Upon investigating the mechanisms whereby ECM components regulate VEGFR‐3 signaling, we found that FN transactivated VEGFR‐3 and significantly enhanced the phosphorylation of VEGFR‐3 induced by VEGF‐C156S as compared to VN. An enhanced association of the integrin subunit α5 or β1 with VEGFR‐3, after stimulation with VEGF‐C156S, was observed by co‐immunoprecipitation. While blockade of integrin α5β1 inhibited the VEGF‐C156S‐induced phosphorylation of VEGFR‐3, no similar effect was obtained by blocking integrin αvβ3. FN also protected the endothelial cells from serum deprivation‐induced apoptosis. Moreover, while the specific PI3 kinase inhibitor, LY294002, abolished this FN‐mediated cell survival, the MAPK kinase inhibitor, PD98059, had no significant effect. Furthermore, a dominant‐negative mutant of VEGFR‐3 (G857R) reduced VEGF‐C156S or FN‐mediated cell survival, as well as the activities of PI3 kinase/Akt. Our results indicate that integrin α5β1 participates in the activation of both VEGFR‐3 and its downstream PI3 kinase/Akt signaling pathway, which is essential for FN‐mediated lymphatic endothelial cell survival and proliferation. © 2005 Wiley‐Liss, Inc.
Increased expression of geminin stimulates the growth of mammary epithelial cells and is a frequent event in human tumors
Authors: Montanari Micaela , Boninsegna Alma , Faraglia Beatrice , Coco Claudio , Giordano Antonio , Cittadini Achille , Sgambato Alessandro
Published: August 2004

Geminin is a potent inhibitor of origin assembly and re‐replication in multicellular eukaryotes and is a negative regulator of DNA replication during the cell cycle. Thus, it was proposed as an inhibitor of cell proliferation and as a potential tumor suppressor gene. However, the protein was found specifically expressed in proliferating lymphocytes and epithelial cells and up‐regulated in several malignancies. Therefore, geminin is now regarded as an oncogene but its role in tumor development remains unknown. In this study, we evaluated by Western blot analysis the expression of geminin in a series of human cancer cell lines of various histogenetic origin and in a series of human primary colon, rectal, and breast cancers. Expression of geminin was variable in different cell lines and not related to the expression level of the corresponding mRNA. Moreover, geminin was expressed at higher level in 56% and 58% of colon and rectal cancers, respectively, compared with the corresponding adjacent normal mucosa. A high expression of geminin was also detected by immunohistochemistry in 60% of human primary breast cancers. We also transfected a full‐length geminin cDNA in a human non‐tumorigenic and a cancer breast cell lines and obtained derivatives expressing high levels of the protein. Geminin overexpression stimulated cell cycle progression and proliferation in both normal and cancer cells and increased the anchorage—independent growth of breast cancer cells. These results demonstrate that expression of geminin is frequently deregulated in tumor cells and might play an important role in the regulation of cell growth in both normal and malignant cells. © 2005 Wiley‐Liss, Inc.
Upregulation of TNF‐α‐induced ICAM‐1 surface expression by adenylate cyclase‐dependent pathway in human endothelial cells
Authors: Bernot Denis , Peiretti Franck , Canault Matthias , Juhan‐Vague Irène , Nalbone Gilles
Published: August 2004

The level of adhesion molecules expressed at the endothelial cell surface is critical in the control of inflammation. Adenylate cyclase (AC) activity allowing cyclic adenosine monophosphate (cAMP) production can modulate the inflammatory process. We investigated the AC‐dependent modulation of ICAM‐1 surface expression in human umbilical venous endothelial cells (HUVEC). Pretreatment of HUVEC with forskolin significantly upregulated tumor necrosis factor alpha (TNF‐α)‐ and interleukin‐1 alpha (IL1‐α)‐induced ICAM‐1 surface expression exclusively after a prolonged time of incubation with forskolin (at least 7–8 h). A poorly metabolizable analog of cAMP, dibutyryl‐cAMP, mimicked forskolin effect on ICAM‐1 surface expression. Protein kinase A (PKA) inhibitor H89 prevented forskolin effect on ICAM‐1 surface expression. Upregulation of ICAM‐1 surface level occurred through the increase in its mRNA levels and also to a subsequent activation of ICAM‐1 intracellular trafficking towards cell surface. Stimulation by agonists of β‐adrenergic receptors did not alter the TNF‐α‐induced ICAM‐1 surface expression. Pretreatment of HUVEC with pertussis toxin, which is known to activate AC through Giα inhibition, upregulated mRNA levels and surface expression of ICAM‐1 induced by TNF‐α. This effect was serum‐dependent, since ICAM‐1 expression was no more upregulated by pertussis toxin in cells cultured in 1% instead of 20% serum‐enriched medium. However, forskolin treatment of HUVEC did not modify their overall adhesive properties. In conclusion, a persistent cAMP level elevation activating PKA is able to enhance ICAM‐1 expression at the cell surface of endothelial cells placed under pro‐inflammatory conditions. Combination of activation of gene transcription and membrane targeting may account for this augmentation. © 2004 Wiley‐Liss, Inc.
Direct analysis for performance‐based design of steel and composite structures
Authors: Richard Liew J Y , Chen H
Published: August 2004

There is a worldwide trend for modern design specifications to depart from prescriptive methods and to move towards performance‐based design approaches. The gradual shift towards performance‐based design increases the need to have efficient and robust direct analysis methods to assess the global performance of structures. Considerable research has been conducted on nonlinear analysis methods in steel and composite members and frames over the last decade. Whilst their use has been limited to the investigation of structural failure and detailed member behaviour, the emergence of high‐speed computers and pre‐ and post‐processing graphic software has led to an increased reliance of direct analysis for designing large‐scale structural systems. This paper reviews some of the principles related to the use of direct analysis for performance‐based design of steel and composite frames, and discusses the issues that are essential for implementation in practice. Illustrative examples are given to show the benefits of using direct analysis for evaluating the overall performance of structural systems in terms of serviceability, ultimate strength and also under exceptional conditions (accidental design situations).
Noncovalent intermolecular energetics: RDX crystal
Authors: Politzer Peter , Ma Yuguang
Published: August 2004

A methodology for using electronic densities to determine electrostatic, polarization, and total energies of noncovalent interactions is summarized and applied to two key molecular pair combinations in the crystal lattice of RDX (hexahydro‐1,3,5‐trinitro‐s‐triazine). It is found that the total interaction energies can be well approximated as purely electrostatic between RDX molecules in the chair–AAE conformation. However, Mulliken and CHelpG point‐charge models are not adequate for reproducing these energies. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Site‐specific N‐glycosylation analysis: matrix‐assisted laser desorption/ionization quadrupole‐quadrupole time‐of‐flight tandem mass spectral signatures for recognition and identification of glycopeptides
Authors: Krokhin Oleg , Ens Werner , Standing Kenneth G. , Wilkins John , Perreault Hélène
Published: August 2004

The identification of glycosylation sites in proteins is often possible through a combination of proteolytic digestion, separation, mass spectrometry (MS) and tandem MS (MS/MS). Liquid chromatography (LC) in combination with MS/MS has been a reliable method for detecting glycopeptides in digestion mixtures, and for assigning glycosylation sites and glycopeptide sequences. Direct interfacing of LC with MS relies on electrospray ionization, which produces ions with two, three or four charges for most proteolytic peptides and glycopeptides. MS/MS spectra of such glycopeptide ions often lead to ambiguous interpretation if deconvolution to the singly charged level is not used. In contrast, the matrix‐assisted laser desorption/ionization (MALDI) technique usually produces singly charged peptide and glycopeptide ions. These ions require an extended m/z range, as provided by the quadrupole‐quadrupole time‐of‐flight (QqTOF) instrument used in these experiments, but the main advantages of studying singly charged ions are the simplicity and consistency of the MS/MS spectra. A first aim of the present study is to develop methods to recognize and use glycopeptide [M+H]+ ions as precursors for MS/MS, and thus for glycopeptide/glycoprotein identification as part of wider proteomics studies. Secondly, this article aims at demonstrating the usefulness of MALDI‐MS/MS spectra of N‐glycopeptides. Mixtures of diverse types of proteins, obtained commercially, were prepared and subjected to reduction, alkylation and tryptic digestion. Micro‐column reversed‐phase separation allowed deposition of several fractions on MALDI plates, followed by MS and MS/MS analysis of all peptides. Glycopeptide fractions were identified after MS by their specific m/z spacing patterns (162, 203, 291 u) between glycoforms, and then analyzed by MS/MS. In most cases, MS/MS spectra of [M+H]+ ions of glycopeptides featured peaks useful for determining sugar composition, peptide sequence, and thus probable glycosylation site. Peptide‐related product ions could be used in database search procedures and allowed the identification of the glycoproteins. Copyright © 2004 John Wiley & Sons, Ltd.
Channel estimation and interference suppression for uplink CDMA mobile communication systems
Authors: Zheng Zi‐Wei , Yang Zhi‐Xing , Zhu Yi‐Sheng , Pan Chang‐Yong
Published: August 2004

Wireless communications for mobile telephone and data transmission is currently undergoing very rapid development. Code division multiple‐access (CDMA) implemented with direct sequence spread spectrum signaling is among the most promising multiplexing technologies for cellular telecommunications services. In this paper, jointly period inserted pilot symbols assisted recursive (PIPSAR) channel estimation and interference suppression techniques are proposed for uplink CDMA mobile communication systems. The uplink CDMA mobile communication system model is described in the form of space‐time domain through antenna array and multipath expression. Interference suppression is achieved by using adaptive minimum mean squared error (MMSE) digital filters that span several successive received chip oversampling vectors of a symbol interval. PIPSAR techniques are used to estimate channel parameters. The correlation between the successive periods is considered to further improve the performance of the proposed scheme. Analysis and simulations are used to evaluate the performance of the proposed scheme. Copyright © 2004 John Wiley & Sons, Ltd.
Radio resource metric estimation for a TDD‐CDMA system supporting wireless internet traffic
Authors: Lee Yeonwoo , McLaughlin Steve
Published: August 2004

In this paper, the effect of wireless internet traffic on the functionality of a radio resource metric estimation (RME) applicable to a TDD‐CDMA system which incorporates a multirate transmission scheme (such as multicode and multislot) with simple call admission control algorithm is investigated. A solution for efficient inter‐working between the physical layer and the higher layers is proposed, a resource metric mapping function (RMMF) that can deliver information about the state of the current channel load condition by the monitoring of signal‐to‐interference ratio (SIR) bursts and also the availability of a code pool by estimating the mean and the standard deviation of SIR bursts. This function is defined and demonstrated by means of an average raw BER mapping diagram as a function of the mean and the standard deviation of SIR bursts according to the multirate transmission method. By using this kind of mapping function combined with throughput estimation, the radio resource allocation algorithm can successfully reflect the current interference and mobile radio channel characteristics. Copyright © 2004 John Wiley & Sons, Ltd.
A survey of QoS enhancements for IEEE 802.11 wireless LAN
Authors: Ni Qiang , Romdhani Lamia , Turletti Thierry
Published: August 2004

Quality‐of‐service (QoS) is a key problem of today's IP networks. Many frameworks (IntServ, DiffServ, MPLS etc.) have been proposed to provide service differentiation in the Internet. At the same time, the Internet is becoming more and more heterogeneous due to the recent explosion of wireless networks. In wireless environments, bandwidth is scarce and channel conditions are time‐varying and sometimes highly lossy. Many previous research works show that what works well in a wired network cannot be directly applied in the wireless environment. Although IEEE 802.11 wireless LAN (WLAN) is the most widely used IEEE 802.11 wireless LAN (WLAN) standard today, it cannot provide QoS support for the increasing number of multimedia applications. Thus, a large number of 802.11 QoS enhancement schemes have been proposed, each one focusing on a particular mode. This paper summarizes all these schemes and presents a survey of current research activities. First, we analyze the QoS limitations of IEEE 802.11 wireless MAC layers. Then, different QoS enhancement techniques proposed for 802.11 WLAN are described and classified along with their advantages/drawbacks. Finally, the upcoming IEEE 802.11e QoS enhancement standard is introduced and studied in detail. Copyright © 2004 John Wiley & Sons, Ltd.
A versatile toolbox for PCR‐based tagging of yeast genes: new fluorescent proteins, more markers and promoter substitution cassettes
Authors: Janke Carsten , Magiera Maria M. , Rathfelder Nicole , Taxis Christof , Reber Simone , Maekawa Hiromi , Moreno‐Borchart Alexandra , Doenges Georg , Schwob Etienne , Schiebel Elmar , Knop Michael
Published: August 2004

Tagging of genes by chromosomal integration of PCR amplified cassettes is a widely used and fast method to label proteins in vivo in the yeast Saccharomyces cerevisiae. This strategy directs the amplified tags to the desired chromosomal loci due to flanking homologous sequences provided by the PCR‐primers, thus enabling the selective introduction of any sequence at any place of a gene, e.g. for the generation of C‐terminal tagged genes or for the exchange of the promoter and N‐terminal tagging of a gene. To make this method most powerful we constructed a series of 76 novel cassettes, containing a broad variety of C‐terminal epitope tags as well as nine different promoter substitutions in combination with N‐terminal tags. Furthermore, new selection markers have been introduced. The tags include the so far brightest and most yeast‐optimized version of the red fluorescent protein, called RedStar2, as well as all other commonly used fluorescent proteins and tags used for the detection and purification of proteins and protein complexes. Using the provided cassettes for N‐ and C‐terminal gene tagging or for deletion of any given gene, a set of only four primers is required, which makes this method very cost‐effective and reproducible. This new toolbox should help to speed up the analysis of gene function in yeast, on the level of single genes, as well as in systematic approaches. Copyright © 2004 John Wiley & Sons, Ltd.
Linkages among adolescent girls’ romantic relationships, best friendships, and peer networks
Authors: Kuttler Ami Flam , La Greca Annette M
Published: August 2004

This study examined the linkages among girls’ best friendships and romantic relationships and accounted for the level of dating involvement as a moderating variable. Social exchange and Sullivan's socioemotional theories served as guides in this process. Questionnaires were administered to 446 girls aged 15–19 years. Results showed that: (a) dating is associated with more positive and less negative interactions with best friends; (b) increasing age and dating involvement are linked with increased reliance on romantic partners; (c) romantic relationships have more negative interactions than best friendships; and (d) peer‐network size and structure is related to dating behaviour. Mid to late adolescence is a time when girls shift attention away from friends and towards romantic partners.
Rearrangement of nuclear ribonucleoprotein (RNP)‐containing structures during apoptosis and transcriptional arrest
Authors: Biggiogera Marco , Bottone Maria Grazia , Scovassi Anna Ivana , Soldani Cristiana , Vecchio Lorella , Pellicciari Carlo
Published: August 2004

Abstract The aim of this paper is to review the data in the literature concerning ribonucleoprotein components during apoptosis, where a major rearrangement of RNPs takes place. In parallel with chromatin changes, the nucleoplasmic constituents (perichromatin fibrils; perichromatin granules; interchromatin granules and nuclear bodies) as well as the nucleoli aggregate into heterogeneous clusters called HERDS, in the interchromatin space. Later, these RNP‐containing structures are extruded from the nucleus and leave the cell within cytoplasmic blebs. We propose also a role for HERDS as markers of irreversible transcriptional arrest.
Time-on-task effect in trait anhedonia
Authors: Dubal Stéphanie , Jouvent Roland
Published: August 2004

The capacity to sustain attention was explored in a sample of anhedonic subjects according to the Chapman physical anhedonia scale. Sustained attention was determined by studying task-induced changes over the duration of the Eriksen response competition task [Percept. Psychophys. 16 (1974) 143]. Anhedonic subjects had longer reaction times (RTs), but missed no more targets than control subjects. Anhedonic subject RTs got longer with time-on-task (TOT) and displayed greater intra-subject variability. These results confirm those of a previous study indicating that anhedonic subjects may have developed a more conservative response strategy [Psychophysiology 37 (2000) 711] and suggest that this strategy may result in a more rapid decrease in energetical resources. Moreover, the greater intra-subject variability demonstrates the importance of assessing performance over time and its relationship to the variability of responses in the cognitive performance of anhedonic subjects.
Predictors of work disabilities in patients with panic disorder with agoraphobia
Authors: Latas Milan , Starcevic Vladan , Vucinic Dusanka
Published: August 2004

Objective

The aim of this study was to ascertain predictors of work insufficiency in patients with panic disorder (PD) with agoraphobia (AG).

Method

Linear regression was used to identify predictors of work insufficiency in a sample of 72 consecutive outpatients with PD with AG. Intensity of work insufficiency was ascertained from modified National Institute of Mental Health Panic Questionnaire (NIMH PQ). That represented dependent variable. Independent variables were demographic data, duration of illness, presence of comorbid current major depression episode, presence of any personality disorder and scores on the Panic and Agoraphobia Scale (PAS) subscales: panic attacks, AG (avoidance behavior), anticipatory anxiety and worries about health.

Results

Patients reported severe work insufficiency. The best predict variable for the work insufficiency in patients with PD with AG was high score on the PAS dimension of AG.

Conclusion

Patients generally reported severe effects of PD with AG on work efficacy and the results suggested that the impaired work efficacy was the most associated with avoidance behavior. These results recommend that the treatment of PD with AG patients should be related to decreasing avoidance behavior in order to establish adequate work performance in patients.
Zerumbone, a tropical ginger sesquiterpene, activates phase II drug metabolizing enzymes
Authors: Nakamura Yoshimasa , Yoshida Chiho , Murakami Akira , Ohigashi Hajime , Osawa Toshihiko , Uchida Koji
Published: August 2004

Zerumbone (ZER), a sesquiterpene compound occurring in tropical ginger Zingiber zerumbet Smith, has been implicated as one of the promising chemopreventive agents against colon and skin cancer. In the present study, we investigated the phase II detoxification enzymes induction of ZER using a cultured rat normal liver epithelial cell line. Exposure of RL34 cells to ZER resulted in the significant induction of glutathione S‐transferase, while the reduced analogues of ZER (α‐humulene and 8‐hydroxy‐α‐humulene) did not show any inducing effect. Therefore, the electrophilic property, characterized by the reactivity with intracellular nucleophiles including protein sulfhydryls as well as low molecular weight thiols, at the 8‐position α,β‐unsaturated carbonyl group plays an important role in the induction of phase II enzymes. ZER induced nuclear localization of the transcription factor Nrf2 that binds to antioxidant response element (ARE) of the phase II enzyme genes, suggesting that ZER is a potential activator of the Nrf2/ARE‐dependent detoxification pathway. This is consistent with the observation that ZER potentiated the gene expression of several Nrf2/ARE‐dependent phase II enzyme genes, including γ‐glutamylcysteine synthetase, glutathione peroxidase, and hemeoxygenase‐1. The present study also implied the antioxidant role of this detoxification system activation by ZER in the neutralization of lipid peroxidation in hepatocytes, providing a new insight for cancer prevention.
DKT1, a novel K+ channel from carrot, forms functional heteromeric channels with KDC1
Authors: Formentin Elide , Varotto Serena , Costa Alex , Downey Patrick , Bregante Monica , Naso Alessia , Picco Cristiana , Gambale Franco , Lo Schiavo Fiorella
Published: August 2004

We report the isolation and characterisation of DKT1, a new carrot K+ channel α‐subunit belonging to the Shaker‐like family. DKT1 is expressed in many tissues of the adult plant, suggesting that it may play important roles in both nutrition and other important physiological processes. During embryo development, DKT1 is expressed at later phases implying the involvement of K+ in embryo maturation. When co‐expressed with KDC1 in Xenopus oocytes, DKT1 is able to form functional, heteromeric channels, suggesting that possible interactions between these two ion channels in plant tissues may modulate K+ uptake.
The Chinese and Japanese communist parties: three decades of discord and reconciliation, 1966–1998
Authors: Berton Peter
Published: August 2004

This article depicts a painful period in the relations between the Chinese and Japanese communist parties. Using a case study of relations between a ruling Chinese communist party and a non-ruling Japanese communist party, the article covers negotiations and communique ´ between the JCP leader Miyamoto and CCP leadershipin 1966 that was overruled by Mao Zedong on the issue of Soviet ‘‘revisionism’’ and revolutionary line for the JCP. It discusses the resulting breakdown of negotiations and CCP’s efforts to splinter the Japanese party by setting up a pro-Beijing Japanese communist group. The article analyzes the obstacles to normalization, and the reasons why the leadershipof the two parties decided to compromise and reach normalization in 1998 after 30 years of acrimony.
Lake-level changes during the past 100,000 years at Lake Baikal, southern Siberia
Authors: Urabe Atsushi , Tateishi Masaaki , Inouchi Yoshio , Matsuoka Hirokazu , Inoue Takahiko , Dmytriev Alexsander , Khlystov Oleg M.
Published: August 2004

Lake-level changes inferred from seismic surveying and core sampling of the floor of Lake Baikal near the Selenga River delta can be used to constrain regional climatic history and appear to be correlated to global climate changes represented by marine oxygen isotope stages (MIS). The reflection pattern and correlation to the isotope stages indicate that the topset and progradational foreset sediments of the deltas formed during periods of stable lake levels and warm climatic conditions. During warm stages, the lake level was high, and during cold stages it was low. The drop in the lake level due to cooling from MIS 5 through MIS 4 is estimated to be 33–38 m; from MIS 3 through MIS 2, it fell an additional 11–15 m. Because the lake level is chiefly controlled by evaporation and river input, we infer that more water was supplied to Lake Baikal during warm stages.
Contemporary tectonic deformation of the Basin and Range province, western United States: 10 years of observation with the Global Positioning System
Authors: Hammond William C. , Thatcher Wayne
Published: August 2004

We have estimated patterns and rates of crustal movement across 800 km of the Basin and Range at ∼39° north latitude with Global Positioning System surveys in 1992, 1996, 1998, and 2002. The total rate of motion tangent to the small circle around the Pacific‐North America pole of rotation is 10.4 ± 1.0 mm/yr, and motion normal to this small circle is 3.9 ± 0.9 mm/yr compared to the east end of our network. On the Colorado Plateau the east end of our network moves by ∼1–2 mm/yr westerly with respect to North America. Transitions in strain rates delimit six major tectonic domains within the province. These deformation zones coincide with areas of modern seismicity and are, from east to west, (1) east‐west extension in the Wasatch Fault zone, (2) low rate east‐west extension centered near the Nevada‐Utah border, (3) low rate east‐west contraction between 114.7°W and 117.9°W, (4) extension normal to and strike‐slip motion across the N10°E striking Central Nevada Seismic Zone, (5) right lateral simple shear oriented N13°W inside the Walker Lane Belt, and (6) shear plus extension near the Sierra Nevada frontal faults. Concentration of shear and dilatational deformation across the three westernmost zones suggests that the Walker Lane Belt lithosphere is rheologically weak. However, we show that linear gradients in viscosity and gravitational potential energy can also effectively concentrate deformation. In the Basin and Range, gradients in gravitational potential are spatially anticorrelated with dilatational strain rates, consistent with the presence of horizontal variations in viscosity of the lithosphere.
Multielemental analysis and characterization of fine aerosols at several key ACE‐Asia sites
Authors: Cohen David D. , Garton David , Stelcer Eduard , Hawas Olga , Wang Tao , Poon Steven , Kim Jiyoung , Choi Byoung Cheol , Oh Sung Nam , Shin Hye‐Jung , Ko Mi Young , Uematsu Mitsuo
Published: August 2004

PM2.5 and PM10 particle size fractions were measured every Wednesday and Sunday for an 18‐month period from 1 January 2001 at three key ACE‐Asia sites: Hong Kong, Cheju Island in southern Korea, and Sado Island in Japan. Median 24 hour PM2.5 mass loadings of 29, 16, and 9.1 μg/m3 and coarse mass loadings of 33, 14, and 11 μg/m3 were measured at Hong Kong, Cheju, and Sado Island sites, respectively, during the study period. The corresponding maximum PM2.5 and coarse mass values for the three sites were 109, 81, and 78 μg/m3 and 101, 162, and 253 μg/m3, respectively. Accelerator‐based ion beam analysis (IBA) techniques were used to quantify major components as well as significant trace elements. These included total hydrogen, black carbon, F, Na, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, and Pb, with detection limits close to or below 1 ng/m3. The average PM2.5 percentage composition by weight across the three sites was estimated to be around (8.4 ± 4)% black carbon, (7.7 ± 7)% soil, (43 ± 14)% ammonium sulfate, (11 ± 16)% organic matter, (10 ± 12)% salinity, and (0.6 ± 0.3)% trace elements. Soil fingerprints for the east Asian region were generated using oxides of measured Al, Si, K, Ca, Ti, Mn, and Fe concentrations. The coarse fraction was dominated by wind blown soil (23%) and sea salts (48%). [PM10/PM2.5] mass ratios were typically (2.1 ± 0.4) averaged across all sites for the whole year. [PM10/PM2.5] mass ratios for the 21 IBA elements analyzed were also provided. This quantitative data providing both masses and dates over an 18‐month period provide useful input for aerosol transport modeling for the east Asia region.
Seabed erosion on the Lomonosov Ridge, central Arctic Ocean: A tale of deep draft icebergs in the Eurasia Basin and the influence of Atlantic water inflow on iceberg motion?
Authors: Kristoffersen Y. , Coakley B. , Jokat W. , Edwards M. , Brekke H. , Gjengedal J.
Published: August 2004

The submarine Lomonosov Ridge, which bisects the Arctic Ocean, is covered by ∼450 m of hemipelagic sediments. High‐resolution chirp sonar and side‐scan data have documented erosion of a section of the ridge. Here we present multichannel seismic and chirp sonar data which show removal of unconsolidated sediments along the Eurasia Basin side of the Lomonosov Ridge, where the central ridge is shallower than 1000 m. The incomplete erosion of the hemipelagic drape and probable topographic control of ice motion suggest that the deepest draft glacier ice, which reached the central Arctic Ocean from the Eurasia Basin, was in the form of armadas of large icebergs embedded in sea ice rather than a single, continuous floating ice shelf. Massive, rapid discharge of glacier ice was probably required to produce the deepest draft (>800 m) icebergs. Eastward and northward drift trajectories from a likely iceberg source area on the Kara‐Barents Sea margin would reflect the relative strength of Atlantic inflow through the Fram Strait. However, only icebergs with drafts exceeding bathymetric thresholds on the Lomonosov Ridge would leave an erosive imprint on the seabed. Advection of Atlantic water may have been relatively strong at times of discharge from the Saalian ice sheet. Icebergs exiting the Arctic Ocean caused massive erosion and redeposition of the hemipelagic sediments on top of Yermak Plateau.
Gibbs sampling for conditional spatial disaggregation of rain fields
Authors: Onibon Hubert , Lebel Thierry , Afouda Abel , Guillot Gilles
Published: August 2004

Gibbs sampling is used to simulate Sahelian rain fields conditional to an areal estimate provided either as the output of an atmospheric model or by a satellite rainfall algorithm. Whereas various methods are widely used to generate simulated rain fields conditioned on point observations, there are many fewer simulation algorithms able to produce a spatially disaggregated rain field of known averaged value. The theoretical and practical aspects of Gibbs sampling for the purpose of conditional rain field simulation are explored in the first part of the paper. It is proposed to used a so‐called acceptation‐rejection algorithm to ensure convergence of the conditional simulation. On a Sahelian case study, it is then showed that Gibbs sampling performs similarly to the well‐known turning band method in an unconditional mode. A preliminary validation of the method in conditional mode is presented. Several rain fields are simulated conditionally on an observed rainfield, whose only the spatial average over a 100 × 100 km2area is supposed to be known. These conditional simulations are compared with the observed rain field and to other rain fields of similar magnitude. For a given class of events, the conditional rain fields have a distribution of point values similar to the distribution of observed point values. At the same time, the model is producing a wide range of spatial patterns corresponding to a single area average, giving an idea of the variety of possible fields of equal areal value.
New insights into the burial history of organic carbon on the early Earth
Authors: Bjerrum Christian J. , Canfield Donald E.
Published: August 2004

The isotope record of organic matter and calcium carbonate is often used to infer the burial history of organic carbon through time. As organic carbon burial is widely held to control long‐term oxygen production, the isotope record also relates to the production rates of oxygen on Earth. Current interpretations of the record suggest a long‐term consistency in the proportion of total carbon buried as organic carbon (f ratio), with some important periods of much higher burial proportions. The isotope record is analyzed here with a new carbon isotope mass balance model, which considers submarine hydrothermal weathering of ocean crust as a significant removal pathway of inorganic carbon. With this model the f ratio is considerably reduced if isotopically depleted inorganic carbon is precipitated during hydrothermal weathering and if hydrothermal weathering dominates inorganic carbon removal from the surface environment. In contrast to previous calculations, our analysis of the carbon isotope record shows that organic carbon burial in the Archean accounted for only between 0% and 10% of the total carbon burial. These low burial proportions would have contributed to a slow accumulation of atmospheric oxygen in the Archean.
Size change of Asian dust particles caused by sea salt interaction: Measurements in southwestern Japan
Authors: Zhang Daizhou , Iwasaka Yasunobu
Published: August 2004

Water dialysis was applied to remove water‐soluble components in the individual Asian dust particles collected in southwestern Japan. Size and composition of the particles before and after the dialysis were compared. It was found that the post‐dialysis number‐size distributions of mineral‐sea salt mixture particles shifted toward smaller ranges compared to their pre‐dialysis distributions and the more sea salt the particles contained the larger the shift of their distribution was, while the dialysis did not cause apparent changes in size or morphology of particles in which sea salt was not identified. Estimation from total detected dust particles revealed that mixing with sea salt had caused their size distributions to shift to larger ranges approximately by 0.4 ∼ 0.8 μm. Hence, the interaction of dust particles and sea salt is likely an important process in size and composition changes of dust particles during their long range transport, consequently affecting mass transformation and radiation transfer in the atmosphere as well as the sedimental flux of mineral dust to sea surface.
A 14‐year European Cloud Climatology from NOAA/AVHRR data in comparison to surface observations
Authors: Meerkötter Ralf , König Christine , Bissolli Peter , Gesell Gerhard , Mannstein Hermann
Published: August 2004

A 14‐year (1990–2003) high resolution European Cloud Climatology has been generated by use of NOAA/AVHRR data. For selected areas we present spatially averaged monthly means of total cloud cover derived from noon overpasses and compare them with surface SYNOP observations. The climatologies do not reveal a significant trend of cloud cover over the 14‐year period. However, both data sets show a clear latitudinal variability and a seasonal dependence which is more pronounced in the satellite than in the SYNOP observations. Mean differences between satellite and SYNOP data range from about −2% to −10% in all seasons except summer when the mean difference is as large as −15.3%. As a special feature we notice the broad minimum of cloud cover during the extreme dry and hot summer in 2003 in Central Europe.
Second‐order random wave solutions for internal waves in a two‐layer fluid
Authors: Song Jin‐Bao
Published: August 2004

The equations describing the random displacement of the density interface and the associated velocity potentials in a constant depth, two‐layer fluid with a rigid lid were solved to second order using an expansion technique analogous to that used to study random surface waves by Longuet‐Higgins [1963] and Sharma and Dean [1979]. As expected, the first‐order solutions represent a linear superposition of many waves with different amplitudes, wave numbers and frequencies. The second‐order solutions describe the second‐order wave‐wave interactions. The solutions derived from the present work include as special cases those obtained by Thorpe for progressive internal waves [Thorpe, 1968a] and standing internal waves [Thorpe, 1968b]. Moreover, the solutions reduce to those derived for random surface waves by Sharma and Dean [1979] when the density of the upper fluid is taken as zero.
Observed changes in the South Indian Ocean gyre circulation, 1987–2002
Authors: Palmer Matthew D. , Bryden Harry L. , Hirschi Joël , Marotzke Jochem
Published: August 2004

We use hydrographic data at 32°S from 1987, 1995 and 2002 to investigate changes in the strength of the subtropical gyre circulation in the Indian Ocean. Relative geostrophic transports are computed for the ocean interior using geopotential anomalies and a zero‐velocity surface at 2230 dbar and then filtered with an 8° Gaussian to remove the high wavenumbers. Our estimates of the relative gyre transports are: 41 ± 5.1 Sv (1 Sv = 106 m3s−1) for 1987, 42 ± 7.0 Sv for 1995 and 58 ± 7.0 Sv for 2002. This represents a 40% increase from 1987 to 2002. The main areas of change in the geostrophic transports are just east of Madagascar Ridge and around Broken Plateau, which is consistent with differences we observe in the isopycnal depths in these areas. Maps of contoured velocity suggest that most of the change happened between 1995 and 2002, which supports our transport estimates.
Dynamic coordinates for auroral ion outflow
Authors: Andersson L. , Peterson W. K. , McBryde K. M.
Published: August 2004

The ionosphere provides a large and variable fraction of the plasma that makes up the Earth's magnetosphere. The sparseness of ion outflow observations and limitations of global magnetospheric models have limited progress in understanding how spatial and temporal variations in the ionospheric component of the magnetosphere affects magnetospheric processes such as storms and substorms. Moreover, because existing comprehensive ion outflow data sets are not organized in terms of large‐scale, dynamic, magnetospheric features, they cannot be used as boundary conditions or ground truth for large‐scale magnetospheric models. This paper presents a method to self‐consistently generate dynamic auroral zone boundaries from ion and electron data obtained on the same platform with mass‐resolved ion outflow observations. We show that this dynamic coordinate system can be used to organize the ion outflow observations so that they are compatible to use with large‐scale magnetospheric models.
A quantitative assessment of the 1998 carbon monoxide emission anomaly in the Northern Hemisphere based on total column and surface concentration measurements
Authors: Yurganov L. N. , Blumenstock T. , Grechko E. I. , Hase F. , Hyer E. J. , Kasischke E. S. , Koike M. , Kondo Y. , Kramer I. , Leung F.‐Y. , Mahieu E. , Mellqvist J. , Notholt J. , Novelli P. C. , Rinsland C. P. , Scheel H. E. , Schulz A. , Strandberg A. , Sussmann R. , Tanimoto H. , Velazco V. , Zander R. , Zhao Y.
Published: August 2004

Carbon monoxide abundances in the atmosphere have been measured between January 1996 and December 2001 in the high Northern Hemisphere (HNH) (30°–90°N) using two different approaches: total column amounts of CO retrieved from infrared solar spectra and CO mixing ratios measured in situ at ground‐based stations. The data were averaged, and anomalies of the CO HNH burden (deviations of the total tropospheric mass between 30°N and 90°N from the mean seasonal profile, determined as the 5 year average) were analyzed. The anomalies obtained from in situ and total column data agree well and both show two maxima, by far the largest in October 1998 and a lower one in August 1996. A noticeable decrease of the positive 1998 summer anomaly with increasing height was found. A box model was applied, and anomalies in source rates were obtained under the assumption of insignificant interannual sink variations. In August 1998 the HNH emission anomaly was estimated to be 38 Tg month−1. The annual 1998 emission positive anomaly was 96 Tg yr−1. Nearly all excess CO may be attributed to the emissions from boreal forest fires. According to available inventories, biomass burning emits around 52 Tg yr−1 during the “normal” years; therefore total biomass emissions in 1998 were as large as 148 Tg yr−1. In August 1998, CO contribution from the biomass burning was twice as large as that from fossil fuel combustion. The results were compared to available emission inventories.
Strong feedbacks between hydrology and sliding of a small alpine glacier
Authors: Anderson Robert S. , Anderson Suzanne P. , MacGregor Kelly R. , Waddington Edwin D. , O'Neel Shad , Riihimaki Catherine A. , Loso Michael G.
Published: August 2004

We report the spatial and temporal pattern of sliding on the 7‐km‐long Bench Glacier, Alaska. Using five continuously recording GPS antennas following motion of the surface ice, distributed at 1 km spacing along the glacier center line, we documented surface ice motion over 50 days during summer 2002. Surface speeds in two previous winters constrain the motion component associated with ice deformation, allowing isolation of the sliding speed history. We observed two speedup events bracketing 2 weeks of steady slow sliding. The first event was not associated with a meteorological trigger, was more subtle than the second, and propagated up‐glacier at a rate of several hundred meters per day. The second event coincided with a warm up‐valley wind, which triggered considerable melt of the glacier surface. Sliding speeds in this event reached 0.3 m d−1 and began almost simultaneously at all sites in the ablation area. Both the horizontal and vertical displacement time series can be explained by growth and collapse of cavities in the lee of bumps in the bedrock bed. Cavities grow during rapid sliding and decay by viscous creep. We posit that effective pressure, averaged over some large area of the bed, is inversely proportional to the sliding speed. This effective pressure then controls the collapse rate of cavities, whose dimensions are estimated from a plausible, stepped‐bed geometry. This model explains well the horizontal and vertical surface displacement history through the first event and beginning of the second event. The vertical record demands a substantial and abrupt drop in water pressure that departs from the posited sliding‐effective pressure relationship. We argue that this pressure drop reflects establishment of efficient subglacial drainage, also manifested in a nearly simultaneous step increase in water discharge in the exit stream. The establishment of an efficient conduit system terminates sliding; its maintenance inhibits further sliding over the remainder of the summer.
Experimental study of liquid‐gas flow structure effects on relative permeabilities in a fracture
Authors: Chen Chih‐Ying , Horne Roland N. , Fourar Mostafa
Published: August 2004

Two‐phase flow through fractured media is important in geothermal, nuclear, and petroleum applications. In this research an experimental apparatus was built to capture the unstable nature of the two‐phase flow in a smooth‐walled fracture and display the flow structures under different flow configurations in real time. The air‐water relative permeability was obtained from experiment and showed deviation from the X curve behavior suggested by earlier studies. Through this work the relationship between the phase channel morphology and relative permeability in fractures was determined. A physical tortuous channel approach was proposed to quantify the effects of the flow structure. This approach could replicate the experimental results with a good accuracy. Other relative permeability models (viscous coupling model, X curve model, and Corey curve model) were also compared. Except for the viscous coupling model, these models did not interpret the experimental relative permeabilities as well as the proposed tortuous channel model. Hence we concluded that the two‐phase relative permeability in fractures depends not only on liquid type and fracture geometry but also on the structure of the two‐phase flow.