bluuebunny/crossref_metadata_2025 huggingface dataset:
Association of Common Haplotypes of Surfactant Protein A1 and A2 (SFTPA1 and SFTPA2) Genes with Severity of Lung Disease in Cystic Fibrosis
Authors: Choi Eun Hwa , Ehrmantraut Mary , Foster Charles B. , Moss Joel , Chanock Stephen J.
Published: January 2006

Most individual cystic fibrosis transmembrane conductance regulator (CFTR) mutations appear not to correlate directly with severity of lung damage in cystic fibrosis (CF). Components of innate immunity, namely, mannose‐binding lectin (MBL2), and surfactant protein A1 and A2 genes (SFTPA1 and SFTPA2), were shown to be critical in pulmonary host defenses. A pilot association study was conducted to identify genetic modifiers of lung disease in adult patients with CF. The structural and promoter (−221x/y) variants of MBL2, variants at codons 19, 50, 62, and 219 of SFTPA1, and at codons 9, 91, and 223 for SFTPA2, were studied in 135 adults with CF and compared to their forced expired volume in 1 sec (FEV1), diffusion of CO (DLCO), and other pulmonary scores. Predicted FEV1 was significantly lower in adults with the SFTPA1 6A3 allele and SFTPA2 1A1 allele (P = 0.01 and 0.009, respectively). The extended haplotype 6A3/1A1, which includes SFTPA1 and SFTPA2, was associated with lower pulmonary function, using FEV1 (P = 0.005) and poor pulmonary scores which were determined by American Medical Association, American Thoracic Society, and modified Shwachman‐Kulczycki scores. Lower FEV1 and DLCO values were associated with MBL2 coding variants in those who had the ΔF508 CFTR mutation (P = 0.03 and 0.004, respectively). These results support the current hypothesis that variants in pulmonary host defense molecules are potentially genetic modifiers of pulmonary disease in CF. Further work in larger populations is required to provide important new insights into the pathogenesis of CF. Pediatr Pulmonol. © 2006 Wiley‐Liss, Inc.
Characterizations of chitosan‐ammonium triflate (NH4CF3SO3) complexes by FTIR and impedance spectroscopy
Authors: Ahmad Khiar A. S. , Puteh R. , Arof A. K.
Published: January 2006

Polymer electrolytes using chitosan and ammonium triflate (NH4CF3SO3) were prepared using the solution cast technique. FTIR confirms the complexation of chitosan and NH4CF3SO3 with shifting of the amine peak at 1591 cm–1 to 1573 cm–1. The highest conducting sample contains 50 wt% of NH4CF3SO3 and at room temperature has a conductivity of 8.91 × 10–7 S cm–1. The model of Rice and Roth has been used to calculate the number density of mobile ions (n), mobility (μ) and diffusion constant (D). Conductivity was found to be dependent on the number of mobile ions. Analysis of electrical modulus and dissipation factor (tan δ) shows that charge transport occurs through a hopping mechanism. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Observation of enhanced long‐lasting phosphorescence in Y2O2S:RE3+ (RE = Lu, Gd) phosphors
Authors: Liu Chunbo , Che Guangbo
Published: January 2006

The long‐lasting phosphorescence properties of Y2O2S:RE3+ (RE = Lu, Gd) phosphors and the undoped Y2O2S matrix are systematically investigated in this paper. The brightness and persistent time of the defect‐related emission around 540 nm in the undoped Y2O2S matrix are greatly enhanced when doped with Lu3+ or Gd3+ ions. Thermoluminescence measurement has been performed and the possible mechanism of this phenomenon was also investigated on the basis of the thermoluminescence data. Based on the time dependence of the phosphorescence intensity, the long‐lasing phosphorescence in this system is considered to be due to the thermally activated electron–hole recombination at shallow traps. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of the electric field on BN conical structures
Authors: Azevedo Sérgio , de Brito Mota Fernando
Published: January 2006

We apply first‐principles calculations to investigate the effect of the electric field on boron nitride conical structures. The studies involve nanocones with different disclination angles. We applied fields of 0.3 V/Å and 0.6 V/Å parallel to the cone axis. It is shown that a small field does not affect the stability of such structures; however, for a larger field, a decrease of 0.1 eV/atom for all structures is observed. We also find modification in the energy gap due to the intensity of the electric field. The bandgap decreased proportionally to the intensity of the electric field, indicating that these results have consequences in the field emission properties of these structures. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Predicting identity consolidation from self‐construction, eudaimonistic self‐discovery, and agentic personality
Authors: Schwartz Seth J.
Published: January 2006

The present study was conducted to ascertain the extent to which three alternative perspectives on identity development (self‐construction, eudaimonistic self‐discovery, and agentic personality) relate to various indices of identity consolidation drawn from Erikson, identity status, and identity capital. A total of 183 participants (21% males; 78% ethnic minorities) completed measures drawn from Eriksonian, identity status, self‐construction, eudaimonistic self‐discovery, and identity capital perspectives. Self‐construction, eudaimonistic self‐discovery, and agentic personality (as operationalized within the identity capital model) each showed differential patterns of relationships to measures of identity consolidation, suggesting that all three strategies can be used to develop a sense of identity.
Multiple solutions of supercritical elliptic problems in perturbed domains
Authors: Molle Riccardo , Passaseo Donato
Published: January 2006

We are concerned with existence and multiplicity of nontrivial solutions for the Dirichlet problem

\mathrm{\Delta }u + |u|^{p−2}u = 0

in

Ω

,

u = 0

on

∂Ω

, where

Ω

is a bounded domain of

\mathbb{R}^{n}

,

n \geq 3

, and

p > \frac{2n}{n−2}

. We show that suitable perturbations of the domain, which modify its topological properties, give rise to a number of solutions which tends to infinity as the size of the perturbation tends to zero (some examples show that the perturbed domains may be even contractible). More precisely, we prove that for all

k \in \mathbb{N}

, if the size of the perturbation is small enough (depending on

k

), there exist at least

k

pairs of nontrivial solutions, which concentrate near the perturbation as the size of the perturbation tends to zero. The method we use, which is completely variational, gives also further informations on the qualitative properties of the solutions; in particular, these solutions (which may change sign) do not have more than

k

nodal regions and at least two solutions (which minimize the corresponding energy functional) have constant sign.

Nous étudions l'existence et la multiplicité de solutions pour le problème de Dirichlet

\mathrm{\Delta }u + |u|^{p−2}u = 0

,

u≢0

en

Ω

,

u = 0

sur

∂Ω

, où

Ω

est un ouvert borné de

\mathbb{R}^{n}

,

n \geq 3

, et

p > \frac{2n}{n−2}

. Nous démontrons que l'existence et le nombre de solutions sont liés à certaines perturbations du domaine, qui modifient ses propriétés topologiques. Chaque perturbation dépend d'un paramètre

ɛ

(l'épaisseur de la perturbation) ; quand

ɛ\rightarrow 0

, le nombre de solutions tend à l'infini et les solutions se concentrent près de la perturbation (des examples montrent que les domaines perturbés peuvent même être contractiles). Plus précisément, nous prouvons que pour tout

k\in \mathbb{N}

il existe

ɛ_{k} > 0

tel que, pour tout

ɛ\in ]0,ɛ_k[

, le problème a au moins

k

paires de solutions. La méthode que nous suivons, qui est complètement variationnelle, donne aussi des informations sur les propriétés qualitatives des solutions. En particulier, ces solutions (qui peuvent changer de signe) ne peuvent pas avoir plus que

k

régions nodales ; de plus, au moins deux solutions (qui minimisent la fonctionnelle de l'énergie) ont signe constant.
Forced vibrations of wave equations with non-monotone nonlinearities
Authors: Berti Massimiliano , Biasco Luca
Published: January 2006

We prove existence and regularity of periodic in time solutions of completely resonant nonlinear forced wave equations with Dirichlet boundary conditions for a large class of non-monotone forcing terms. Our approach is based on a variational Lyapunov–Schmidt reduction. It turns out that the infinite dimensional bifurcation equation exhibits an intrinsic lack of compactness. We solve it via a minimization argument and a-priori estimate methods related to the regularity theory of [P. Rabinowitz, Periodic solutions of nonlinear hyperbolic partial differential equations, Comm. Pure Appl. Math. 20 (1967) 145–205].

On prouve l'existence et la régularité de solutions périodiques en temps d'équations des ondes non linéaires forcées, complètement résonnantes, avec des conditions au bord de Dirichlet, pour une grande classe de termes forcants non-monotones. Notre approche est basée sur une réduction de Lyapunov–Schmidt variationnelle. L'équation de bifurcation en dimension infinie présente un manque intrinsèque de compacité. Nous la résolvons par un argument de minimisation et à l'aide d'estimations a priori inspirées de la théorie de la régularité de [P. Rabinowitz, Periodic solutions of nonlinear hyperbolic partial differential equations, Comm. Pure Appl. Math. 20 (1967) 145–205].
Inhibition of MCF‐7 breast cancer cell proliferation by MCF‐10A breast epithelial cells in coculture
Authors: Spink Barbara C. , Cole Richard W. , Katz Barbara H. , Gierthy John F. , Bradley Laurie M. , Spink David C.
Published: January 2006

A coculture system was developed to investigate the interactions between MCF‐10A breast epithelial cells and MCF‐7 breast cancer cells stably expressing the green fluorescent protein (MCF‐7‐GFP). Studies with this MCF‐10A/MCF‐7‐GFP coculture system on microtiter plates and on reconstituted basement membrane (Matrigel), revealed paracrine inhibition of MCF‐7‐GFP cell proliferation. Epidermal growth factor, which in monocultures modestly enhanced MCF‐7‐GFP and markedly increased MCF‐10A cell proliferation, greatly inhibited MCF‐7‐GFP cell proliferation in MCF‐10A/MCF‐7‐GFP cocultures. 17β‐Estradiol, which stimulated MCF‐7‐GFP but not MCF‐10A cell proliferation in monoculture, inhibited MCF‐7‐GFP cell proliferation in MCF‐10A/MCF‐7‐GFP cocultures, an effect that was blocked by the antiestrogen, ICI 182,780. On Matrigel, complex MCF‐10A/MCF‐7‐GFP cellular interactions were observed in real time that resulted in the formation of acinus‐like structures. These results indicate a role of normal epithelial cells in inhibiting tumor‐cell proliferation and demonstrate the utility of this coculture system as a model of early paracrine control of breast cancer.
Expression of APOBEC2 is transcriptionally regulated by NF‐κB in human hepatocytes
Authors: Matsumoto Tomonori , Marusawa Hiroyuki , Endo Yoko , Ueda Yoshihide , Matsumoto Yuko , Chiba Tsutomu
Published: January 2006

Apolipoprotein B mRNA‐editing enzyme catalytic subunit 2 (APOBEC2) is a member of the nucleic‐acid‐editing enzymes. However, the physiological function of APOBEC2 remains unclear. We demonstrate that APOBEC2 expression is strongly enhanced in response to both tumour necrosis factor‐α (TNF‐α) and interleukin‐1β. Inhibition of NF‐κB activation invariably blocks TNF‐α‐induced APOBEC2 expression. The promoter region of APOBEC2 contains functional NF‐κB response elements in the 5′ untranslated region of the gene at −625/−616. These results show that APOBEC2 expression is regulated by pro‐inflammatory cytokines via NF‐κB activation and suggest a possible role of APOBEC2 in the pathophysiology of hepatic inflammation.
Metabolic engineering of coenzyme Q by modification of isoprenoid side chain in plant
Authors: Takahashi Sakiko , Ogiyama Yuki , Kusano Hiroaki , Shimada Hiroaki , Kawamukai Makoto , Kadowaki Koh-ichi
Published: January 2006

Coenzyme Q (CoQ), an electron transfer molecule in the respiratory chain and a lipid‐soluble antioxidant, is present in almost all organisms. Most cereal crops produce CoQ9, which has nine isoprene units. CoQ10, with 10 isoprene units, is a very popular food supplement. Here, we report the genetic engineering of rice to produce CoQ10 using the gene for decaprenyl diphosphate synthase (DdsA). The production of CoQ9 was almost completely replaced with that of CoQ10, despite the presence of endogenous CoQ9 synthesis. DdsA designed to express at the mitochondria increased accumulation of total CoQ amount in seeds.
Characterization of human thioredoxin‐like‐1: Potential involvement in the cellular response against glucose deprivation
Authors: Jiménez Alberto , Pelto-Huikko Markku , Gustafsson Jan-Åke , Miranda-Vizuete Antonio
Published: January 2006

The thioredoxin system, composed of thioredoxin (Trx) and thioredoxin reductase (TrxR), emerges as one of the most important thiol‐based systems involved in the maintenance of the cellular redox balance. Thioredoxin‐like‐1 (TXL‐1) is a highly conserved protein comprising an N‐terminal Trx domain and a C‐terminal domain of unknown function. Here we show that TXL‐1 is a substrate for the cytosolic selenoprotein TrxR‐1. In situ hybridization experiments demonstrates high expression of Txl‐1 mRNA in various areas of central nervous system and also in some reproductive organs. Glucose deprivation, but not hydrogen peroxide treatment, reduced the levels of endogenous TXL‐1 protein in HEK‐293 cell line. Conversely, overexpression of TXL‐1 protects against glucose deprivation‐induced cytotoxicity. Taken together, the finding that Txl‐1 mRNA is highly expressed in tissues which use glucose as a primary energy source and the modulation of TXL‐1 levels upon glucose deprivation indicate that TXL‐1 might be involved in the cellular response to sugar starvation stress.
Characterization of severe acute respiratory syndrome coronavirus membrane protein
Authors: Voß Daniel , Kern Anika , Traggiai Elisabetta , Eickmann Markus , Stadler Konrad , Lanzavecchia Antonio , Becker Stephan
Published: January 2006

The coronavirus membrane protein (M) is the key player in the assembly of virions at intracellular membranes between endoplasmic‐reticulum and Golgi‐complex. Using a newly established human monoclonal anti‐M antibody we detected glycosylated and nonglycosylated membrane‐associated M in severe acute respiratory syndrome‐associated coronavirus (SARS‐CoV) infected cells and in purified virions. Further analyses revealed that M contained a single N‐glycosylation site at asparagine 4. Recombinant M was transported to the plasma membrane and gained complex‐type N‐glycosylation. In SARS‐CoV infected cells and in purified virions, however, N‐glycosylation of M remained endoglycosidase H‐sensitive suggesting that trimming of the N‐linked sugar side chain is inhibited.
Downregulation of protein kinase CKII is associated with cellular senescence
Authors: Ryu Seok-Woo , Woo Ju Hyung , Kim Young-Ho , Lee Young-Sup , Park Jeen Woo , Bae Young-Seuk
Published: January 2006

Protein kinase CKII (CKII) plays a critical role in cell growth and proliferation. In this study, we examine how CKII activity is regulated during cellular senescence. Our results demonstrate that CKII activity apparently decreases during both replicative and H2O2‐induced senescence in human diploid fibroblast IMR‐90 cells. The mRNA and protein levels of CKIIα decreases significantly during replicative and H2O2‐induced senescence, while only slight reduction in those of CKIIβ is observed during replicative senescence. Treatment of IMR‐90 cells with CKII inhibitors 5,6‐dichloro‐1‐β‐d‐ribofuranosylbenzimidazole and apigenin led cells to acquire a senescent phenotype as judged by the senescence‐associated β‐galactosidase marker and overexpression of p53 and p21Waf‐1. Knockdown of CKIIα in IMR‐90 cells by RNA interference also dramatically induced the senescent phenotype. In parallel, CKII activity was transcriptional downregulated in rat liver and testis with advancing age. Taken together, these results suggest that downregulation of CKII activity is tightly associated not only with cellular senescence but also with organism aging.
Muscarinic acetylcholine receptor inhibition in transgenic Alzheimer‐like Tg2576 mice by scopolamine favours the amyloidogenic route of processing of amyloid precursor protein
Authors: Liskowsky Wolfgang , Schliebs Reinhard
Published: January 2006

The molecular mechanisms of the interrelationship between cholinergic neurotransmission, processing of amyloid precursor protein (APP) and β‐amyloid (Aβ) production in vivo are still less understood. To reveal any effect of cholinergic dysfunction on APP processing in vivo, 11‐month‐old transgenic Tg2576 mice with Aβ plaque pathology received intraperitoneal injections of scopolamine at a daily dosage of 2 mg/kg body weight for 14 days in order to suppress cortical cholinergic transmission by chronic inhibition of muscarinic acetylcholine receptors. Scopolamine treatment of transgenic Tg2576 mice resulted in increased levels of fibrillar Aβ(1–40) and Aβ(1–42), while the soluble, SDS‐extractable Aβ level remained unchanged as compared to vehicle‐injected Tg2576 mice. α‐Secretase activity determined in cortical tissue from scopolamine‐treated Tg2576 mice was lower by about 30% as compared to that assayed in control mice, while β‐secretase activity and BACE1 protein expression appeared unaffected by scopolamine treatment. The amount of sAPPα, the product secreted by α‐secretase‐mediated APP cleavage, and the unprocessed APP were assayed in the soluble and membrane fraction, respectively, of cortical tissue preparations from treated and control mice by Western blotting. Using the anti antibody 6E10 which specifically labels human sAPPα and full length APP in transgenic Tg2576, an enhanced APP level was detected in the membrane fraction from treated mice as compared to controls, while in the soluble fraction scopolamine treatment did not affect the protein level of sAPPα. These data indicate an accumulation of APP in cortical membrane fraction in scopolamine‐treated Tg2576 mice presumably due to the decreased level of α‐secretase‐mediated APP cleavage, and further suggest that chronic suppresion of cortical muscarinic cholinergic transmission may alter the balance between α‐ and β‐secretory APP processing by favouring the amyloidogenic route.
Postpartum hemorrhage in resource‐poor settings
Authors: Geller S.E. , Adams M.G. , Kelly P.J. , Kodkany B.S. , Derman R.J.
Published: January 2006

Despite the strong interest of international health agencies, worldwide maternal mortality has not declined substantially over the past 10 years. Postpartum hemorrhage (PPH) is the most common cause of maternal death across the world, responsible for more than 25% of deaths annually. Although effective tools for prevention and treatment of PPH are available, most are not feasible or practical for use in the developing world where many births still occur at home with untrained birth attendants. Application of many available clinical solutions in rural areas would necessitate substantial changes in government infrastructure and in local culture and customs surrounding pregnancy and childbirth. Before treatment can be administered, prompt and accurate diagnosis must be made, which requires training and appropriate blood measurement tools. After diagnosis, appropriate interventions that can be applied in remote settings are needed. Many uterotonics known to be effective in reducing PPH in tertiary care settings may not be useful in community settings because they require refrigeration and/or skilled administration. Moreover, rapid transfer to a higher level of care must be available, a challenge in many settings because of distance and lack of transportation. In light of these barriers, low‐technological replacements for treatments commonly applied in the developed‐world must be utilized. Community education, improvements to emergency care systems, training for birth attendants, misoprostol, and Uniject™ have shown promise as potential solutions. In the short term, it is expedient to capitalize on practical opportunities that utilize the existing strengths and resources in each community or region in order to implement appropriate solutions to save the lives of women during childbirth.
Disentangling leanness and agility: An empirical investigation
Authors: Narasimhan Ram , Swink Morgan , Kim Soo Wook
Published: January 2006

Manufacturing plant managers have sought performance improvements by adhering to the guiding principles of leanness and agility. Lean manufacturing and agile manufacturing paradigms have also received considerable attention in operations management literature. However, paradoxically, the extant literature is lacking in clarity and fails to delineate with sufficient precision how and why leanness and agility differ. Given the resource constraints within which most manufacturing firms have to operate today, it is useful, if not critical, to develop a good understanding of how these paradigms differ and what their constituent dimensions are. Such an understanding is also essential for developing and testing theories relating to leanness and agility.

Through a literature review we discuss leanness and agility in two ways: (1) as manufacturing paradigms and (2) as performance capabilities. Our empirical study attempts to determine whether lean and agile forms occur with any degree of regularity in manufacturing plants. The results confirm the existence of homogeneous groups that resemble lean and agile performing plants, and they identify important differences pertaining to their constituent performance dimensions. The results indicate that while the pursuit of agility might presume leanness, pursuit of leanness might not presume agility. While the performance capability differences across the empirically derived groups accord well with expected differences across plants that excel in leanness and agility, the practice differences across the groups are not as clearly distinguished. We discuss the implications of our findings for further research and theory development.
Spatial Processing and Perceptual Sequence Learning in SRT Tasks
Authors: Deroost Natacha , Soetens Eric
Published: January 2006

We investigated the influence of processing relevant spatial information on learning a probabilistic sequence of irrelevant locations. Using the SRT design of Remillard (2003 ), we found that spatial perceptual learning occurs with paired but not with single targets. The pairs of targets consisted of the same stimuli, but in a different order, so that responses could have been based on the left-right location of an element, relative to the other element of the pair. The prerequisite of spatial pairs of targets suggests that spatial processing of relevant information plays a crucial role in perceptual location learning. In addition, spatial perceptual learning only took place when the target pair was presented together with other stimuli, but was absent when the target pair was presented in a blank field. Since in the latter case attention is automatically captured, this suggests that sequence learning requires endogenous attention.
Selective Stopping in Task Switching
Authors: Verbruggen Frederick , Liefooghe Baptist , Vandierendonck André
Published: January 2006

Recently, several studies stressed the role of response selection in cued task switching. The present study tried to investigate directly the hypothesis that no switch cost can be found when there was no response selection. In two experiments, we combined a cued task switching paradigm with the selective stopping paradigm. Results of the experiments demonstrated that a switch cost was found when participants selected a response, even without response execution. Alternatively, when the response was inhibited without the need of response selection, no switch cost was found. These results provide direct evidence for the distinct role of response selection in cued task switching and suggest that response execution is not a necessary factor to obtain a switch cost.
Further Evidence that the SNARC Effect is Processed Along a Dual-Route Architecture
Authors: Gevers Wim , Ratinckx Elie , De Baene Wouter , Fias Wim
Published: January 2006

In a binary response setting, it has been frequently observed that small numbers are reacted to faster with the left hand and large numbers with the right hand (i. e., the SNARC-effect) which reflects the spatial left-right orientation of the mental number line ( Dehaene, Bossini, & Giraux, 1993 ). In line with the work of Keus and Schwarz (in press ), we investigated the locus of the conflict in the SNARC effect in a parity judgment task with the Arabic numerals 1, 2, 8, or 9. Differences between compatible (left-hand response to 1 or 2 and right-hand response to 8 and 9) and incompatible SNARC conditions (left-hand response to 8 or 9 and right-hand response to 1 or 2) were observed in the lateralized readiness potential (LRP) but not in the peak latency of the P300. In accordance with Keus and colleagues ( Keus, Jenks, & Schwarz, 2005 ), we argue that the locus of the conflict is situated at intermediate response-related stages. However, instead of adopting a single-route processing architecture, a dual route account is proposed as the underlying processing architecture explaining the SNARC effect.
Employing Automatic Approach and Avoidance Tendencies for the Assessment of Implicit Personality Self-Concept
Authors: Schnabel Konrad , Banse Rainer , Asendorpf Jens
Published: January 2006

A new chronometric procedure, the Implicit Association Procedure (IAP), was adapted to assess the implicit personality self-concept of shyness. A sample of 300 participants completed a shyness-inducing role play and, before or after the role play, a shyness IAP, a shyness Implicit Association Test (IAT), and direct self-ratings. The experimental group was instructed to fake nonshyness. The control group did not receive this instruction. IAT and IAP were unaffected by position effects, and were less susceptible to faking than direct self-ratings with regard to mean levels and correlates. Under faking, correlations between direct and indirect measures decreased, and direct but not indirect measures showed higher correlations with social desirability and lower correlations with observed shyness. Despite many similarities, the true correlation between IAT and IAP was estimated only .61, indicating high method-specific variance in both procedures. The findings suggest that indirect measures are more robust against faking than traditional self-ratings but do not yet meet psychometric criteria for practical assessment purposes.
Transonic neutral wind in the thermosphere observed by the DE 2 satellite
Authors: Balthazor R. L. , Bailey G. J.
Published: January 2006

DE 2 Wind And Temperature Spectrometer (WATS) instrument data has been analyzed to investigate supersonic excursions of the measured neutral wind. There have been 488 supersonic events identified, with the zonal component of the neutral wind Mach number M in the range 1 < M < 2. These events are located in the polar cap, predominantly between 75 and 85 degrees MLT in the dawn sector. The events are located broadly spread over the height range 300–600 km. The mean horizontal linear extent of the regions of supersonic flow is estimated to be around 140 km. We find an anticorrelation between Mach number (for 1 < M < 2) and neutral temperature, which may be due to adiabatic cooling of the thermosphere from thermospheric heat sources below the satellite altitude.
Detachment folding–related Miocene submarine slope instability in the Romagna Apennines (Italy)
Authors: Bonini Marco
Published: January 2006

The relationships between slope failure and growing thrust‐related structures have been explored in the Miocene Marnoso‐Arenacea foredeep basin (Romagna Apennines). Impressive fossil slump layers are distributed along the footwall of the regional Mount Nero thrust, which evolved from detachment fold to breakthrough thrust. During the detachment fold stage, development of growth strata on the rotating forelimb was preceded by the emplacement of slump layers that are currently part of the Mount Nero thrust footwall. In this process, sliding is assumed to nucleate along the contacts between different lithologies in the semiconsolidated rock mass. The conditions of sliding, specifically the critical angle of sliding αcrit, are quantified by adding the influence of cohesion of sediments to the equilibrium analysis reported in Hubbert and Rubey's (1959) classical work. The resulting angles αcrit are discussed with respect to the depth of the basal surface of sliding and pore fluid pressure states. On the basis of such an analysis and field work results, an evolutionary model is proposed in which slide sheets come from the crest and upper forelimb of growing detachment folds and attain a deeper detachment depth as the forelimb rotates and steepens. Pore fluid pressure is found to play a major role by radically decreasing the critical angle of sliding. Likewise, localization of overpressures may also control the depth of sliding during progressive forelimb rotation. To allow sliding along gently dipping bedding surfaces, slope failure is interpreted as being related to the reactivation of anisotropies represented by lithological discontinuities.
Comparison of methods for deriving aerosol asymmetry parameter
Authors: Andrews E. , Sheridan P. J. , Fiebig M. , McComiskey A. , Ogren J. A. , Arnott P. , Covert D. , Elleman R. , Gasparini R. , Collins D. , Jonsson H. , Schmid B. , Wang J.
Published: January 2006

Values for Mie‐equivalent aerosol asymmetry parameter (g) were derived using a variety of methods from the large suite of measurements (in situ and remote from surface and aircraft) made in Oklahoma during the 2003 aerosol Intensive Operations Period (IOP). Median values derived for dry asymmetry parameter at 550 nm ranged between 0.55 and 0.63 over all instruments and for all derivation methods, with the exception of one instrument which did not measure over the full size range of optically important aerosol. Median values for the “wet” asymmetry parameter (i.e., asymmetry parameter at humidity conditions closer to ambient) were between 0.59 and 0.72. Values for g derived for surface and airborne in situ measurements were highly correlated, but in situ and remote sensing measurements both at the surface and aloft did not agree as well because of vertical inhomogeneity of the aerosol. Radiative forcing calculations suggest that a 10% decrease in g would result in a 19% reduction in top of atmosphere radiative forcing for the conditions observed during the IOP. Comparison of the different methods for deriving g suggests that in computing the asymmetry parameter, aerosol size is the most important parameter to measure; composition is less important except for how it influences the hygroscopic growth (i.e., size) of particles.
Nitrate attenuation in agricultural catchments: Shifting balances between transport and reaction
Authors: Ocampo Carlos J. , Oldham Carolyn E. , Sivapalan Murugesu
Published: January 2006

Simultaneous observations, across multiple spatial and temporal scales, are needed to understand the complex interactions between hydrological and biogeochemical processes in catchments and the primary controls on NO3− availability and mobility. This paper addresses these issues by using data collected from a detailed field experiment, carried out on two topographically different hillslopes (one steep and the other flat) located within an agricultural catchment in Western Australia. Continuous hydrometric data and measurements of chemical tracers, geochemical parameters, and NO3− concentrations taken from the shallow perched aquifer across riparian, midslope, and upland locations were analyzed and interpreted through a simple process‐based numerical model of transport and reaction. The NO3− concentration data indicated that the temporal and spatial patterns of NO3− concentrations within the hillslopes are linked to the state of hydrological connectivity of the three landscape units as the shallow perched aquifer developed during the winter. Significant NO3− attenuation occurs within the riparian zones after the transport of NO3− from midslope sources begins. Application of a mixing model, which partitions the riparian zones into three water source components, and the numerical model of NO3− transport and reaction indicates that different mechanisms, dilution in the steep hillslope and denitrification in the flat hillslope, are responsible for much of the observed NO3− attenuation in the riparian zones. In this way, this work highlights the importance of hillslope topography in determining the relative roles of transport and reaction in NO3− attenuation and export from riparian zones. The experimental results also supported the use of the Damköhler number, a simple dimensionless number that is a measure of the competition between transport and reaction processes, which allowed a favorable comparison of our findings with previous results published in the literature for different geographical settings.
Giant ionospheric disturbances excited by the M9.3 Sumatra earthquake of 26 December 2004
Authors: Liu J. Y. , Tsai Y. B. , Chen S. W. , Lee C. P. , Chen Y. C. , Yen H. Y. , Chang W. Y. , Liu C.
Published: January 2006

An Mw 9.3 earthquake originated in the Indian Ocean off the western coast of northern Sumatra at 00:58:53 Universal Time (UT) on 26 December 2004. Two giant ionospheric disturbances at 01:19 and 04:10 UT are observed by a network of digital Doppler sounders in Taiwan. The first disturbance excited mainly by Rayleigh waves, which consists of a packet of short‐period Doppler shift variations, results in vertical ionospheric fluctuations with a maximum velocity of about 70 m/s and displacement of about 200 m. The second disturbance, in a W‐shaped pulse propagating at a horizontal speed of 360 ± 70 m/s, is attributable to coupling of the atmospheric gravity waves (AGW) excited by broad crustal uplift together with the following big tsunami waves around the earthquake source zone. The accompanying ionosonde data suggest that the AGW in the atmosphere may have caused the ionosphere to move up and down by about 40 km.
An empirical parameterization for the salinity of subsurface water entrained into the ocean mixed layer (Se) in the tropical Pacific
Authors: Zhang Rong‐Hua , Busalacchi Antonio J. , Murtugudde Raghuram G. , Arkin Phillip A. , Ballabrera‐Poy Joaquim
Published: January 2006

An empirical parameterization for Se is proposed and tested in an intermediate ocean model (IOM) of the Tropical Pacific Ocean. An inverse modeling approach is first adopted to estimate Se from a sea surface salinity (SSS) anomaly (SSSA) model using observed in‐situ SSS measurements, simulated upper ocean currents, and freshwater flux (evaporation minus precipitation, E‐P) data. A relationship between Se and sea level (SL) anomalies is then obtained by utilizing an empirical orthogonal function (EOF) technique. This empirical scheme is able to estimate Se anomalies reasonably well in the equatorial Pacific Ocean and can be used to parameterize Se fields in terms of SL anomalies for use in SSSA calculations. An optimized Se parameterization naturally leads to a balanced depiction of the subsurface effect on SSS variability in association with entrainment and vertical mixing. As a result, SSSA simulations can be potentially improved in the Tropical Pacific.
Interpretation of seismic anisotropy in terms of mantle flow when melt is present
Authors: Kaminski E.
Published: January 2006

The use of seismic anisotropy to image upper mantle flow is usually based on the assumption that the direction of fast propagation of seismic waves is the same as the flow direction. Laboratory experiments showed that when melt is present, it is rather the direction of slow propagation that aligns with the flow direction. This paper presents a modeling of the effect of melt on the development of lattice preferred orientation (LPO) and its implications for the interpretation of anisotropy. Taking into account strain partitioning associated with melt segregation in the modeling yields a good agreement with experimental results. Implementing strain partitioning in a test flow shows that the effect of melt is mainly local and has a limited effect on seismic anisotropy. Water‐induced texture, melt‐filled cracks or channelized flow, might better account for seismic observations of direction of fast propagation normal to plate motion on a regional scale.
Current deformation rates and extrusion of the northwestern Okhotsk plate, northeast Russia
Authors: Hindle D. , Fujita K. , Mackey K.
Published: January 2006

Northeast Asia is a region of broad deformation resulting from the convergence of the Eurasian (EU) and North American (NA) plates. Part of this convergence has been suggested to be relieved by the extrusion and deformation of the Okhotsk plate (OK). Three models for the deformation of the seismically active northwestern corner of the Okhotsk plate, based on different modes of deformation partitioning, are calculated and compared to observations from GPS, seismicity, and geology. The results suggest that this region is being extruded southeastward and deforming internally by a mixture of pure contraction, “smooth” extrusion, and “rigid” extrusion. Calculated extrusion rates are ∼3–5.5 mm/yr, comparable to estimates from geologic data, and internal deformation rates are ∼3.0 × 10−9 yr −1. Internal deformation may be only partially accommodated by seismicity, but the short time span of seismic data leaves this subject to large uncertainty.
New insights into the mechanism of postseismic stress relaxation exemplified by the 23 June 2001 Mw = 8.4 earthquake in southern Peru
Authors: Hergert Tobias , Heidbach Oliver
Published: January 2006

The 2001 Mw = 8.4 southern Peru subduction earthquake marked the beginning of a transient postseismic surface motion in direction of the coseismic displacement at the permanent GPS station Arequipa. In general this motion is assigned to afterslip. Our hypothesis is that the observed transient signal can be explained by stress relaxation processes in the overriding plate. We use a 2D finite element model incorporating non‐linear viscoelastic Maxwell rheology. Our model results indicate that coseismically induced stresses are relieved by viscoelastic stress relaxation in the lower crust. The trenchward directed creep motion is transferred to the upper crust due to elastic coupling leading there to an instantaneous relief of elastic stresses. In contrast to the existing conceptual models for stress relaxation, which incorporate shear stresses, we conclude that tensional elastic stresses throughout the crust and upper mantle are the main driving forces for the transient GPS signal.
Carbon and hydrogen isotope constraints on degassing of CO2 and H2O in submarine lavas from the Pitcairn hotspot (South Pacific)
Authors: Aubaud Cyril , Pineau Françoise , Hékinian Roger , Javoy Marc
Published: January 2006

The analysis of CO2–δ13C–H2O–δD in vesicles of 35 submarine volcanic glasses reveals that open‐system degassing, following closed‐system degassing, is responsible for the observed variations in volatile concentration and isotopic ratios. The least degassed samples allow the assessment of minimum estimates for the flux of CO2 and H2O from the Pitcairn hotspot: 2.24 ± 0.17 104 tons C yr−1 and 1.32 ± 0.82 105 tons H2O yr−1. The results also suggest that the carbon in the source of the Pitcairn hotspot may have a δ13C value around −6‰, 2‰ lower than the source of mid‐ocean ridge basalts. This indicates either a possible contribution from the lower mantle or the possible involvement of decarbonated recycled materials with an unusual carbon isotopic signature.
Modulation of anomalous protons: Effects of different solar wind speed profiles in the heliosheath
Authors: Langner U. W. , Potgieter M. S. , Fichtner H. , Borrmann T.
Published: January 2006

Two termination shock acceleration modulation models are used to study the modulation of anomalous protons, in particular the effects of different scenarios for global solar wind speed (V) variations in the heliosheath. The first numerical model simulates a symmetric heliosphere and the second simulates an asymmetric heliosphere with respect to the Sun. The modulation differences between these models are illustrated and discussed. The geometry of the heliosphere in the latter model is deduced from a time‐dependent three‐dimensional hydrodynamic model of the heliosphere which provides the different scenarios for the V‐profiles in the heliosheath. The modulation models include the solar wind termination shock, global drifts, adiabatic energy changes, diffusion, convection, and a heliosheath. The anomalous protons are kinetically described using the Parker transport equation. A solar wind speed decreasing stronger than the generally assumed V ∝ 1/r2 dependence, with r the radial distance from the Sun, is studied as well as an extreme scenario with V ∝ r2. The stronger decrease produces a compressive flow in the heliosheath which results in additional acceleration of anomalous protons in the heliosheath. The solutions are shown for solar minimum and moderate maximum modulation conditions for both heliospheric magnetic field polarity cycles. Significant modulation differences are found to occur between these different scenarios for V in the heliosheath. If the stronger than V ∝ 1/r2 scenarios in the heliosheath are real, the anomalous intensities should increase beyond the TS, which should be measurable by the Voyager 1 spacecraft in the near future.
Seismicity on a fault controlled by rate‐ and state‐dependent friction with spatial variations of the critical slip distance
Authors: Hillers G. , Ben‐Zion Y. , Mai P. M.
Published: January 2006

We perform systematic simulations of slip using a quasi‐dynamic continuum model of a two‐dimensional (2‐D) strike‐slip fault governed by rate‐ and state‐dependent friction. The depth dependence of the a − b and L frictional parameters are treated in an innovative way that is consistent with available laboratory data and multidisciplinary field observations. Various realizations of heterogeneous L distributions are used to study effects of structural variations of fault zones on spatiotemporal evolution of slip. We demonstrate that such realizations can produce within the continuum class of models realistic features of seismicity and slip distributions on a fault. We explore effects of three types of variable L distributions: (1) a depth‐dependent L profile accounting for the variable width of fault zones with depth, (2) uncorrelated 2‐D random distributions of L with different degrees of heterogeneity, and (3) a hybrid distribution combining the depth‐dependent L profile with the 2‐D random L distributions. The first type of L distribution, with relatively small L over the depth range corresponding to the seismogenic zone and larger L elsewhere, generates stick‐slip events in the seismogenic zone and ongoing creep above and below that region. The 2‐D heterogeneous parameterizations generate frequency‐size statistics with event sizes spanning 4 orders of magnitude. Our results indicate that different degrees of heterogeneity of L distributions control (1) the number of simulated events and (2) the overall stress level and fluctuations. Other observable trends are (3) the dependency of hypocenter location on L and (4) different nucleation phases for small and large events in heterogeneous distributions.
Role of pressure gradients in sheet flow of coarse sediments under sawtooth waves
Authors: Calantoni Joseph , Puleo Jack A.
Published: January 2006

Discrete particle model (DPM) simulations have been performed to directly examine the role of horizontal pressure gradients acting on the wave bottom boundary layer (WBBL) during the process of sheet flow transport in the surf zone. The DPM is a two‐phase WBBL model that directly couples a one‐dimensional eddy‐viscosity fluid flow to a three‐dimensional particle model. Newton's Third Law is enforced at every simulation time step through fluid‐particle interaction forces of buoyancy, drag, and added‐mass. Simulations are able to reproduce bedload transport rates from a laboratory data set for coarse sediment distributions. Consequently, simulations of a monochromatic sawtooth wave were performed with three coarse grain size distributions to investigate the relative importance of bed shear stresses, horizontal pressure forces, and fluid‐particle drag forces on bedload transport processes. The simulation results demonstrate that the magnitude of the horizontal pressure force acting directly on sediment embedded in the WBBL is small compared to the magnitude of the particle drag force or particle stress; however, the phasing of the onshore peak in the horizontal pressure force with respect to the particle drag force is important to sediment mobilization and enhances the observed onshore bias in bed load flux. Removing the horizontal pressure force on the sediment particles resulted on average in a 30% reduction in net bed load flux. In the surf zone, free stream fluid accelerations are typically equated to the horizontal pressure gradient. Thus, the simulations may explain why the fluid acceleration can be a successful parameter for aiding in sediment transport predictions in the surf zone.
Dynamics of submarine groundwater discharge and freshwater‐seawater interface
Authors: Taniguchi Makoto , Ishitobi Tomotoshi , Shimada Jun
Published: January 2006

Relationships between submarine groundwater discharge (SGD) and the freshwater‐saltwater interface are evaluated by continuous measurements of SGD rates, conductivity and temperature of SGD, and resistivity measurements across the coastal aquifer. Our measurements show that the processes of SGD differ between the offshore and nearshore environments. SGD and submarine fresh groundwater discharge (SFGD) rates were largest just landward of the saltwater‐freshwater interface. SGD variations landward the saltwater‐freshwater interface had negative correlations with tidal variations, because of the connections of terrestrial groundwater in the land and the ocean. SGD in the nearshore can be explained mainly by connections of terrestrial groundwater, while offshore SGD rate is controlled mostly by oceanic process such as recirculated saline groundwater discharge.
Modeling analysis of the effect of iron enrichment on dimethyl sulfide dynamics in the NE Pacific (SERIES experiment)
Authors: Le Clainche Yvonnick , Levasseur Maurice , Vézina Alain , Bouillon René‐Christian , Merzouk Anissa , Michaud Sonia , Scarratt Michael , Wong Chi Shing , Rivkin Richard B. , Boyd Philip W. , Harrison Paul J. , Miller William L. , Law Cliff S. , Saucier François J.
Published: January 2006

The large‐scale iron enrichment conducted in the NE Pacific during the Subarctic Ecosystem Response to Iron Enrichment Study (SERIES) triggered a phytoplankton bloom dominated successively by nanophytoplankton and large diatoms. During the first 14 days, surface dimethyl sulfide (DMS) levels increased both inside (up to 22 nmol L−1) and outside (up to 19 nmol L−1) the patch, with no consistent Fe effect. Later, DMS concentrations became sixfold lower inside the patch than outside. In this study, we used a DMS budget module embedded in a one‐dimensional ocean turbulence model to investigate the contribution of the interacting physical, photochemical, and biological processes to this particular DMS response. Temporal variations in biological net DMS production were reconstructed using an inverse modeling approach. Our results show that short‐term (days) variations in both the physical processes (i.e., turbulent mixing and ventilation) and the biological cycling of DMS are needed to explain the time evolution of DMS concentrations both outside and inside the Fe‐enriched patch. The biological net DMS production was generally high (up to 0.35 nmol L−1 h−1) and comparable outside and inside the patch during the first 10 days, corresponding to the observed accumulation of DMS inside and outside the patch. Later, it became negative (net DMS biological consumption) inside the patch, suggesting a change in dimethylsulfoniopropionate bacterial metabolism. This study stresses the importance of short‐term variations in biological processes and their sensitivity to the physical environment in shaping the DMS response to iron enrichment.