bluuebunny/crossref_metadata_2025 huggingface dataset:
Hecke C*-Algebras, Schlichting Completions and Morita Equivalence
Authors: Kaliszewski S. , Landstad Magnus B. , Quigg John
Published: October 2008

The Hecke algebra of a Hecke pair (G, H) is studied using the Schlichting completion (Ḡ, ), which is a Hecke pair whose Hecke algebra is isomorphic to and which is topologized so that is a compact open subgroup of Ḡ. In particular, the representation theory and C*-completions of are addressed in terms of the projection using both Fell's and Rieffel's imprimitivity theorems and the identity . An extended analysis of the case where H is contained in a normal subgroup of G (and in particular the case where G is a semi-direct product) is carried out, and several specific examples are analysed using this approach.
Finitary Group Cohomology and Group Actions on Spheres
Authors: Hamilton Martin
Published: October 2008

We show that if G is an infinitely generated locally (polycyclic-by-finite) group with cohomology almost-everywhere finitary, then every finite subgroup of G acts freely and orthogonally on some sphere.
Vulnerable relations: lifecourse, wellbeing and social exclusion in Buenos Aires, Argentina
Authors: LLOYD-SHERLOCK PETER , LOCKE CATHERINE
Published: October 2008

Many have presumed that in developing countries, contact with children is beneficial to older people's wellbeing, and particularly that women receive more support from children than men because of their lifelong commitment to family responsibilities. This study questions these stylised notions through an analysis of 22 life histories of older women and men living in a district with high rates of social exclusion in Buenos Aires, Argentina. It focuses on the subjective accounts of relationships with children and grandchildren and their influence on current wellbeing. The life histories reveal complex lived experiences and the significance of key events. The informants speak of the anxiety and harm caused by struggling children, about problems of remote relations with successful children, and of the insecurity of the neighbourhood. The analysis contrasts a materialistic interpretation of the influence of children on older people's wellbeing with the informants' more holistic evaluation of family relationships. By applying a life-course framework, we demonstrate that children may be a key source of vulnerability for older people, that the gendering of parent-child relations and later-life wellbeing is nuanced, that both local and national conditions influence relationships with specific children, with implications for the intergenerational transmission of wellbeing.
A cross-linguistic investigation of the acquisition of the pragmatics of indefinite and definite reference in two-year-olds
Authors: ROZENDAAL MARGOT ISABELLA , BAKER ANNE EDITH
Published: October 2008

The acquisition of reference involves both morphosyntax and pragmatics. This study investigates whether Dutch, English and French two- to three-year-old children differentiate in their use of determiners between non-specific/specific reference, newness/givenness in discourse and mutual/no mutual knowledge between interlocutors. A brief analysis of the input shows a clear association between form and function, although there are some language differences in this respect. As soon as determiner use can be statistically analyzed, the children show a relatively adult-like pattern of association for the distinctions of non-specific/specific and newness/givenness. The distinction between mutual/no mutual knowledge appears later. Reference involving no mutual knowledge is scarcely evidenced in the input and barely used by the children at this age. The development of associations is clearly related to the rate of determiner development, the French being quickest, then the English, then the Dutch.
The relationship of parenting stress and child temperament to language development among economically disadvantaged preschoolers
Authors: NOEL MELANIE , PETERSON CAROLE , JESSO BEULAH
Published: October 2008

Oral language skills in the preschool years are predictive of children's later reading success and literacy acquisition, and among these language skills, vocabulary and narrative ability play important roles. Children from low socioeconomic families face risks to their language development and because of threats to these skills it is important to identify factors that promote their development among high-risk groups. This preliminary study explored two potential factors that may be related to language skills in 56 low SES mother–child dyads (children aged 2 ; 8–4 ; 10), namely child temperament and parenting stress. Results showed that child temperament and parenting stress were related to children's oral language skills. Child temperament characteristics that would likely aid social interaction were related to narrative ability and children rated high on emotionality had poorer receptive vocabulary skills. Parenting stress was related to children's receptive and expressive vocabulary skills. Results are interpreted in terms of the possible mediating role of parent–child interactions in children's oral language skill development, and future directions for family intervention are discussed.
From emotion resonance to empathic understanding: A social developmental neuroscience account
Authors: Decety Jean , Meyer Meghan
Published: October 2008

The psychological construct of empathy refers to an intersubjective induction process by which positive and negative emotions are shared, without losing sight of whose feelings belong to whom. Empathy can lead to personal distress or to empathic concern (sympathy). The goal of this paper is to address the underlying cognitive processes and their neural underpinnings that constitute empathy within a developmental neuroscience perspective. In addition, we focus on how these processes go awry in developmental disorders marked by impairments in social cognition, such as autism spectrum disorder, and conduct disorder. We argue that empathy involves both bottom-up and top-down information processing, underpinned by specific and interacting neural systems. We discuss data from developmental psychology as well as cognitive neuroscience in support of such a model, and highlight the impact of neural dysfunctions on social cognitive developmental behavior. Altogether, bridging developmental science and cognitive neuroscience helps approach a more complete understanding of social cognition. Synthesizing these two domains also contributes to a better characterization of developmental psychopathologies that impacts the development of effective treatment strategies.
The changing impact of genes and environment on brain development during childhood and adolescence: Initial findings from a neuroimaging study of pediatric twins
Authors: Lenroot Rhoshel K. , Giedd Jay N.
Published: October 2008

Human brain development is created through continuing complex interactions of genetic and environmental influences. The challenge of linking specific genetic or environmental risk factors to typical or atypical behaviors has led to interest in using brain structural features as an intermediate phenotype. Twin studies in adults have found that many aspects of brain anatomy are highly heritable, demonstrating that genetic factors provide a significant contribution to variation in brain structures. Less is known about the relative impact of genes and environment while the brain is actively developing. We summarize results from the ongoing National Institute of Mental Health child and adolescent twin study that suggest that heritability of different brain areas changes over the course of development in a regionally specific fashion. Areas associated with more complex reasoning abilities become increasingly heritable with maturation. The potential mechanisms by which gene–environment interactions may affect heritability values during development is discussed.
The neural bases of obsessive–compulsive disorder in children and adults
Authors: Maia Tiago V. , Cooney Rebecca E. , Peterson Bradley S.
Published: October 2008

Functional imaging studies have reported with remarkable consistency hyperactivity in the orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), and caudate nucleus of patients with obsessive–compulsive disorder (OCD). These findings have often been interpreted as evidence that abnormalities in cortico–basal ganglia–thalamo–cortical loops involving the OFC and ACC are causally related to OCD. This interpretation remains controversial, however, because such hyperactivity may represent either a cause or a consequence of the symptoms. This article analyzes the evidence for a causal role of these loops in producing OCD in children and adults. The article first reviews the strong evidence for anatomical abnormalities in these loops in patients with OCD. These findings are not sufficient to establish causality, however, because anatomical alterations may themselves be a consequence rather than a cause of the symptoms. The article then reviews three lines of evidence that, despite their own limitations, permit stronger causal inferences: the development of OCD following brain injury, pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection, and neurosurgical lesions that attenuate OCD. Converging evidence from these various lines of research supports a causal role for the cortico–basal ganglia–thalamo–cortical loops that involve the OFC and ACC in the pathogenesis of OCD in children and adults.
Polarised subtyping for sized types
Authors: ABEL ANDREAS
Published: October 2008

We present an algorithm for deciding polarised higher-order subtyping without bounded quantification. Constructors are identified not only modulo β, but also η. We give a direct proof of completeness, without constructing a model or establishing a strong normalisation theorem. Inductive and coinductive types are enriched with a notion of size and the subtyping calculus is extended to account for the inclusions arising between the sized types.
Bounded polymorphism in session types
Authors: GAY SIMON J.
Published: October 2008

Session types allow high-level specifications of structured patterns of communication, such as client-server protocols, to be expressed as types and verified by static typechecking. In collaboration with Malcolm Hole, we previously introduced a notion of subtyping for session types, which was formulated for an extended pi calculus. Subtyping allows one part of a system, for example, a server, to be refined without invalidating type-correctness of other parts, for example, clients. In this paper we introduce bounded polymorphism, which is based on the same notion of subtyping, in order to support more precise and flexible specifications of protocols; in particular, a choice of type in one message may affect the types of future messages. We formalise the syntax, operational semantics and typing rules of an extended pi calculus, and prove that typechecking guarantees the absence of run-time communication errors. We study algorithms for checking instances of the subtype relation in two versions of our system, which we call KernelS≤and FullS≤, and establish that subtyping in KernelS≤is decidable, and that subtyping in FullS≤is undecidable.
Bounds For The Real Zeros of Chromatic Polynomials
Authors: DONG F. M. , KOH K. M.
Published: October 2008

Sokal in 2001 proved that the complex zeros of the chromatic polynomialPG(q) of any graphGlie in the disc |q| < 7.963907Δ, where Δ is the maximum degree ofG. This result answered a question posed by Brenti, Royle and Wagner in 1994 and hence proved a conjecture proposed by Biggs, Damerell and Sands in 1972. Borgs gave a short proof of Sokal's result. Fernández and Procacci recently improved Sokal's result to |q| < 6.91Δ. In this paper, we shall show that all real zeros ofPG(q) are in the interval [0,5.664Δ). For the special case that Δ = 3, all real zeros ofPG(q) are in the interval [0,4.765Δ).
B2[g] Sets and a Conjecture of Schinzel and Schmidt
Authors: CILLERUELO JAVIER , VINUESA CARLOS
Published: October 2008

A set of integers is called a B2[g] set if every integer m has at most g representations of the form m = a + a′, with a ≤ a′ and a, a′ ∈ . We obtain a new lower bound for F(g, n), the largest cardinality of a B2[g] set in {1,. . .,n}. More precisely, we prove that infn→∞$\frac{F(g, n)}{\sqrt{gn}}\geq \frac 2{\sqrt \pi}-\e_g$ where ϵg → 0 when g → ∞. We show a connection between this problem and another one discussed by Schinzel and Schmidt, which can be considered its continuous version.
Influence of hyaluronan accumulation during cumulus expansion onin vitroporcine oocyte maturation
Authors: Yokoo Masaki , Kimura Naoko , Abe Hiroyuki , Sato Eimei
Published: October 2008

During oocyte maturation, the cumulus–oocyte complexes (COCs) expand dramatically. This phenomenon, which is known as cumulus expansion, is the result of the synthesis and accumulation of hyaluronan in the extracellular space between cumulus cells. The purpose of this study was to investigate the effect of 6-diazo-5-oxo-l-norleucine (DON), an inhibitor of hyaluronan synthesis, on cumulus expansion duringin vitroporcine oocyte maturation and hyaluronan accumulation within COCs. Further, this study aimed to examine the influence of hyaluronan accumulation within COCs on the rate of oocyte maturation. Cumulus expansion was observed duringin vitromaturation. However, the addition of DON to the maturation medium significantly inhibited cumulus expansion. The total inhibition of hyaluronan accumulation within COCs was observed with the use of confocal microscopy. Moreover, a positive correlation between the area of cumulus expansion and the rate of oocyte maturation was observed. These results demonstrate that the hyaluronan accumulation within the COCs during oocyte maturation affects oocyte maturation. On the basis of these results, we propose that hyaluronan accumulation within the COCs during cumulus expansion is a necessary step in the porcine oocyte maturation process.
Questions de corps de définition pour les variétés abéliennes en caractéristique positive
Authors: Benoist Franck , Delon Françoise
Published: October 2008

Dichotomies in various conjectures from algebraic geometry are in fact occurrences of the dichotomy among Zariski structures. This is what Hrushovski showed and which enabled him to solve, positively, the geometric Mordell–Lang conjecture in positive characteristic. Are we able now to avoid this use of Zariski structures? Pillay and Ziegler have given a direct proof that works for semi-abelian varieties they called ‘very thin’, which include the ordinary abelian varieties. But it does not apply in all generality: we describe here an abelian variety which is not very thin. More generally, we consider from a model-theoretical point of view several questions about the fields of definition of semi-abelian varieties.
De non ordinaria recognitione PSL2
Authors: Deloro Adrien
Published: October 2008

We establish an identification result of the projective special linear group of dimension 2
among a certain class of groups the Morley rank of which is finite.
Circuits arithmétiques et calculs tensoriels
Authors: Malod Guillaume
Published: October 2008

The classes in Valiant's theory are classes of polynomials defined by arithmetic circuits. We characterize them by different notions of tensor calculus, in the vein of Damm, Holzer and McKenzie. This characterization underlines in particular the role played by properties of parallelization in these classes. We also give a first natural complete sequence for the class VPnb, the analogue of the class P in this context.
TRADITIONALIST DISSENT: THE REORIENTATION OF AMERICAN CONSERVATISM, 1865–1900
Authors: HARP GILLIS J.
Published: October 2008

The last couple of decades has brought a renewed interest in American conservatism among historians. Yet most recent studies have focused on the emergence of neoconservatism after World War II and virtually no recent scholarly work has pursued the history of conservatism before the 1920s. Both Richard Hofstadter and Clinton Rossiter agreed that the late nineteenth century was an important watershed in the evolution of American conservative thought. Hofstadter argued that the new laissez-faire conservatism that became dominant during the Gilded Age was remarkable in that “it lacked many of the signal characteristics of conservatism as it is usually found.” Yet some conservatives refused to accept key features of what Clinton Rossiter once branded this new “contradictory conservatism.” This essay focuses mostly on Protestant clerical intellectuals (both Northern and Southern) who dissented from the new orthodoxy and attempted to preserve older conservative principles. Against the laissez-faire conservatives' hyperindividualism, these dissenting conservatives stressed an organic view of the social order and the importance of mediating institutions such as family and church. To the others' secularism, they offered a social theory suffused with evangelical Protestantism. This analysis highlights where these dissidents differed from their fellow conservatives and seeks also to elucidate their alternative conservative vision of the American republic. Such a study serves to clarify just how profound an ideological shift occurred among conservatives during the Gilded Age and illuminates some of the persistent tensions within American conservatism still evident today.
SITE-SPECIFIC: THE FRACTURED HUMANITY OF J. ROBERT OPPENHEIMER
Authors: BORGWARDT ELIZABETH
Published: October 2008

“God knows,” lamented the physicist Isidor Rabi, “I'm not the simplest person, but compared to Oppenheimer, I'm very, very simple.” J. Robert Oppenheimer played myriad roles in the science and politics of modern America: as a physicist working to establish a synthetic American school uniting theoretical and experimental approaches; as a government functionary and “weaponeer” piloting the development and fine-tuning the deployment of the first atomic bombs; as insider, consultant, and oracle speaking in the name of American science; but also as outsider, voice of conscience, and political pariah.
EXPLAINING THE THIRD REICH: ETHICS, BELIEFS, INTERESTS
Authors: PENDAS DEVIN O.
Published: October 2008

In recent years, the historiography of Nazi Germany has taken what Neil Gregor has called a “voluntarist turn.” By this, Gregor means that the recent literature on Nazi Germany has emphasized “that the panoply of organizations actively involved in occupation and murder, the number of German men and women who actively participated in these crimes, and the range of places in which they committed them, was much, much greater than has hitherto been acknowledged.” In the first instance this voluntarist turn has meant an increased stress on the centrality of Nazi criminality and atrocity to the regime, not as one feature, but as the central characteristic, of the Third Reich. Alongside this, however, has come an increased insistence that these criminal policies were both widely known at the time and broadly popular among Germans. As Saul Friedländer has put it, “the everyday involvement of the population with the regime was far deeper than has long been assumed, due to the widespread knowledge and passive acceptance of the crimes, as well as the crassest profit derived from them.” In short, then, the most recent trend among historians of the Third Reich is to insist that people believed in the Nazi project, including its criminal aspects.
Lower mantle tomography and phase change mapping
Authors: Sun Daoyuan , Helmberger Don
Published: October 2008

A lower mantle S wave triplication (Scd) has been recognized for many years and appears to be explained by the recently discovered perovskite (PV) to postperovskite (PPV) phase change. Seismic observations of Scd display (1) rapid changes in strength and timing relative to S and ScS and (2) early arrivals beneath fast lower mantle regions. While the latter feature can be explained by a Clapeyron slope (γ) of 6 MPa/K and a velocity jump of 1.5% when corrected by tomographic predictions, it does not explain the first feature. Here, we expand on this mapping approach by attempting a new parameterization that requires a sample of D" near the ScS bounce point (δVS) where the phase height (hph) and velocity jump (β) are functions of (δVS). These parameters are determined by modeling dense record sections collected from USArray and PASSCAL data where Grand's tomographic model is the most detailed in D" structure beneath Central America. We also address the range of γ to generate new global models of the phase boundary and associated temperature variation. We conclude that a γ near 9 MPa/K is most satisfactory but requires β to be nonuniform with a range from about 1.0 to 4.0% with some slow region samples requiring the largest values. Moreover, the edges of the supposed buckled slabs delimitated by both P and S waves display very rapid changes in phase boundary heights producing Scd multipathing. These features can explain the unstable nature of the Scd phase with easy detection to no detection commonly observed. The fine structure at the base of the mantle beneath these edges contains particularly strong reflections indicative of local ultralow velocity zones, which are predicted in some dynamic models.
Magnetic properties experiments and the Surface Stereo Imager calibration target onboard the Mars Phoenix 2007 Lander: Design, calibration, and science goals
Authors: Leer K. , Bertelsen P. , Binau C. S. , Djernis Olsen L. , Drube L. , Falkenberg T. V. , Haspang M. P. , Madsen M. B. , Olsen M. , Sykulska H. , Vijendran S. , Pike W. T. , Staufer U. , Parrat D. , Lemmon M. , Hecht M. H. , Mogensen C. T. , Gross M. A. , Goetz W. , Marshall J. , Britt D. , Smith P. , Shinohara C. , Woida P. , Woida R. , Tanner R. , Reynolds R. , Shaw A.
Published: October 2008

The first NASA scout mission to Mars, Phoenix, launched 4 August will land in the northern part of Mars in the locality of 68°N and 233°E on 25 May 2008. Part of the science payload is the Magnetic Properties Experiments (MPE) that consists of two main experiments: the Improved Sweep Magnet Experiment (ISWEEP) and 10 sets of two Microscopy, Electrochemistry, and Conductivity Analyzer (MECA) magnet substrates with embedded permanent magnets of different strength. The ISWEEP experiment is, as the name indicates, an improved version of the Sweep Magnet Experiments flown onboard the two Mars Exploration Rovers (MERs) Spirit and Opportunity. The sweep magnet is ring shaped and is designed to allow only nonmagnetic particles to enter a small circular area at the center of the surface of this structure. Results from this experiment have shown that on the MERs hardly any particles can be detected in the central area of this ring‐shaped magnet. From this we have concluded that essentially all particles in the Martian atmosphere are magnetic in the sense that they are attracted to permanent magnets. In order to improve the sensitivity of the Sweep Magnet Experiment for detection of nonmagnetic or very weakly magnetic particles, the ISWEEP holds six ring‐shaped magnets, somewhat larger than the sweep magnet of the MERs, and with six different background colors in the central area. The six different colors provide new possibilities for improved contrast between these background colors, i.e., any putative nonmagnetic particles should render these more easily detectable. The Surface Stereo Imager will also take advantage of the small clean areas in the ISWEEPs and use the presumably constant colors for radiometric calibration of images. The MECA magnets work as substrates in the MECA microscopy experiments; they are built to attract and hold magnetic particles from dust samples. The collected dust will then be examined by the optical microscope and the atomic force microscope in the MECA package.
Distribution and escape of molecular hydrogen in Titan's thermosphere and exosphere
Authors: Cui J. , Yelle R. V. , Volk K.
Published: October 2008

We present an in‐depth study of the distribution and escape of molecular hydrogen (H2) on Titan, based on the global average H2 distribution at altitudes between 1000 and 6000 km, extracted from a large sample of Cassini/Ion and Neutral Mass Spectrometer (INMS) measurements. Below Titan's exobase, the observed H2 distribution can be described by an isothermal diffusion model, with a most probable flux of (1.37 ± 0.01) × 1010 cm−2 s−1, referred to the surface. This is a factor of ∼3 higher than the Jeans flux of 4.5 × 109 cm−2 s−1, corresponding to a temperature of 152.5 ± 1.7 K, derived from the background N2 distribution. The H2 distribution in Titan's exosphere is modeled with a collisionless approach, with a most probable exobase temperature of 151.2 ± 2.2 K. Kinetic model calculations in the 13‐moment approximation indicate a modest temperature decrement of several kelvin for H2, as a consequence of the local energy balance between heating/cooling through thermal conduction, viscosity, neutral collision, and adiabatic outflow. The variation of the total energy flux defines an exobase level of ∼1600 km, where the perturbation of the Maxwellian velocity distribution function, driven primarily by the heat flow, becomes strong enough to raise the H2 escape flux considerably higher than the Jeans value. Nonthermal processes may not be required to interpret the H2 escape on Titan. In a more general context, we suggest that the widely used Jeans formula may significantly underestimate the actual thermal escape flux and that a gas kinetic model in the 13‐moment approximation provides a better description of thermal escape in planetary atmospheres.
Where do fossil fuel carbon dioxide emissions from California go? An analysis based on radiocarbon observations and an atmospheric transport model
Authors: Riley W. J. , Hsueh D. Y. , Randerson J. T. , Fischer M. L. , Hatch J. G. , Pataki D. E. , Wang W. , Goulden M. L.
Published: October 2008

Characterizing flow patterns and mixing of fossil fuel‐derived CO2 is important for effectively using atmospheric measurements to constrain emissions inventories. Here we used measurements and a model of atmospheric radiocarbon (14C) to investigate the distribution and fluxes of atmospheric fossil fuel CO2 across the state of California. We sampled 14C in annual C3 grasses at 128 sites and used these measurements to test a regional model that simulated anthropogenic and ecosystem CO2 fluxes, transport in the atmosphere, and the resulting Δ14C of annual grasses (Δg). Average measured Δg levels in Los Angeles, San Francisco, the Central Valley, and the North Coast were 27.7 ± 20.0, 44.0 ± 10.9, 48.7 ± 1.9, and 59.9 ± 2.5‰, respectively, during the 2004–2005 growing season. Model predictions reproduced regional patterns reasonably well, with estimates of 27.6 ± 2.4, 39.4 ± 3.9, 46.8 ± 3.0, and 59.3 ± 0.2‰ for these same regions and corresponding to fossil fuel CO2 mixing ratios (Cf) of 13.7, 6.1, 4.8, and 0.3 ppm. Δg spatial heterogeneity in Los Angeles and San Francisco was higher in the measurements than in the predictions, probably from insufficient spatial resolution in the fossil fuel inventories (e.g., freeways are not explicitly included) and transport (e.g., within valleys). We used the model to predict monthly and annual transport patterns of fossil fuel‐derived CO2 within and out of California. Fossil fuel CO2 emitted in Los Angeles and San Francisco was predicted to move into the Central Valley, raising Cf above that expected from local emissions alone. Annually, about 21, 39, 35, and 5% of fossil fuel emissions leave the California airspace to the north, east, south, and west, respectively, with large seasonal variations in the proportions. Positive correlations between westward fluxes and Santa Ana wind conditions were observed. The southward fluxes over the Pacific Ocean were maintained in a relatively coherent flow within the marine boundary layer, while the eastward fluxes were more vertically dispersed. Our results indicate that state and continental scale atmospheric inversions need to consider areas where mixing ratio measurements are sparse (e.g., over the ocean to the south and west of California), transport within and across the marine boundary layer, and terrestrial boundary layer dynamics. Radiocarbon measurements can be very useful in constraining these estimates.
Neural network treatment of 4 years long NO measurement in temperate spruce and beech forests
Authors: Dupont R. , Butterbach‐Bahl K. , Delon C. , Bruggemann N. , Serça D.
Published: October 2008

NO soil emissions are directly influenced by soil environmental (temperature, humidity), chemical (pH, N content, C content…) and physical (soil content, texture) variables. All these parameters exert linear or non linear influences that fluctuate in threshold and intensity between sites. Because of the lack of field experiments and to the high variability in time (diurnal and seasonal cycle) and space (regions, soil and vegetation type) of the environmental parameters influencing NO emissions, estimates of NO emissions worldwide still remain highly uncertain. In this study we developed nonlinear regressions to describe NO flux emission from soil in dependency with relevant environmental parameters for a forest site in a temperate region (Höglwald, South Germany, 1994–1997) using an Artificial Neural Network (ANN). The resulting algorithm links NO fluxes with air, surface and depth temperatures, surface WFPS (Water Field Pore Space) and humus pH. All these parameters were evaluated and selected as relevant and non redundant. Network performances are evaluated for different numbers of hidden neurons. Resulting equations linking NO fluxes from soils and variables are obtained, and show to perform well with measurements (R2 = 0.81). Average NO fluxes values of 14.6 gN ha−1 d−1 are obtained for calculated and measured fluxes. In a second part, 2002–2003 NO soil fluxes are estimated from the ANN equation obtained from 1994–1997 flux measurements performed at the same site. Overall, simulated results give a good estimation of NO fluxes, with a mean value of 15.3 gN ha d−1 close to the 21.7 gN ha d−1 measured mean for the 2002–2003 period. ANN algorithm gives also a good representation of low frequency (seasonal) variations. On the basis of our results, we suggest that ANN is a good alternative between detailed biogeochemical models and large scale models, and may be the appropriate tool for estimating NO emissions at a regional scale.
New U‐Th/Pb constraints on timing of shearing and long‐term slip‐rate on the Karakorum fault
Authors: Valli Franck , Leloup Philippe Hervé , Paquette Jean‐Louis , Arnaud Nicolas , Li Haibing , Tapponnier Paul , Lacassin Robin , Guillot Stéphane , Liu Dunyi , Deloule Etienne , Xu Zhiqin , Mahéo Gweltaz
Published: October 2008

Zircons and monazites from 6 samples of the North Ayilari dextral shear zone (NAsz), part of the Karakorum fault zone (KFZ), have been dated with the U‐Th‐Pb method, using both ID‐TIMS and SIMS techniques. The ages reveal (1) inheritance from several events spanning a long period between the late Archean and the Jurassic; (2) an Eocene‐Oligocene magmatic event (∼35–32 Ma); (3) an Oligo‐Miocene magmatic event (∼25–22 Ma), at least partly synkinematic to the right‐lateral deformation; and (4) a period of metamorphism metasomatism (∼22–14 Ma) interpreted as thermal and fluid advection in the shear zone. The Labhar Kangri granite located ∼375 km farther Southeast along the KFZ is dated at 21.1 ± 0.3 Ma. Such occurrence of several Oligo‐Miocene granites along the KFZ, some of which show evidence for synkinematic emplacement, suggests that the fault zone played an important role in the genesis and /or collection of crustal melts. We discuss several scenarios for the onset and propagation of the KFZ, and offset estimates based on the main sutures zones. Our preferred scenario is an Oligo‐Miocene initiation of the fault close to the NA range, and propagation along most of its length prior to ∼19 Ma. In its southern half, the averaged long‐term fault‐rate of the KFZ is greater than 8 to 10 mm/a, in good agreement with some shorter‐term estimates based on the Indus river course, or Quaternary moraines and geodesy. Our results show the KFZ cannot be considered as a small transient fault but played a major role in the collision history.
Methyl chloride and isoprene emissions from tropical rain forest in Southeast Asia
Authors: Saito Takuya , Yokouchi Yoko , Kosugi Yoshiko , Tani Makoto , Philip Elizabeth , Okuda Toshinori
Published: October 2008

Methyl chloride (CH3Cl) fluxes were investigated at leaf and forest‐canopy scales in tropical forests in Malaysia. Screening of CH3Cl‐emitting species showed that 21% of 117 tree species were CH3Cl emitters; the percentage was markedly higher for dipterocarps (66%) than non‐dipterocarps (6%). The dipterocarp‐derived CH3Cl was characterized by high emissions (median: 0.03 μg g−1 h−1) and low stable carbon isotope ratios (mean: −88.9 ± 11.0‰). Measurements of CH3Cl above the canopy showed a slight decrease in the mixing ratios with increasing height. These values were used to estimate the canopy‐scale flux of about 14 μg m−2 h−1, comparable to that extrapolated from the leaf‐scale emissions. Using the canopy‐scale flux, global CH3Cl emission by tropical forests was estimated to be 1.3 Tg yr−1, representing approximately 30% of the global emissions. Above‐canopy measurements were also made for isoprene, with a mean flux of 1.2 mg m−2 h−1.
Light‐toned strata and inverted channels adjacent to Juventae and Ganges chasmata, Mars
Authors: Weitz C. M. , Milliken R. E. , Grant J. A. , McEwen A. S. , Williams R. M. E. , Bishop J. L.
Published: October 2008

Light‐toned layered deposits on the plains adjacent to Juventae and Ganges Chasmata have been identified and analyzed with several instruments onboard the Mars Reconnaissance Orbiter, including HiRISE, CTX, and CRISM. Beds exhibit variations in brightness, color, polygonal fracturing, and erosional properties that are not seen in light‐toned layered deposits within the chasmata. At both Juventae and Ganges, the light‐toned layered deposits along the plains have associated features we interpret as fluvial, including sinuous ridges (inverted channels) that exhibit light‐toned layering and an extensive valley system for the Ganges deposit. The strong correlation between the inverted channels and light‐toned layered deposits suggests an association with fluvial‐lacustrine processes, although pyroclastic and eolian activity may also be involved in their emplacement. The identification of potential fluvial‐lacustrine layered deposits and associated valley networks suggests surface water flow in the Valles Marineris region that occurred for sustained periods during the Hesperian (3.7–3.0 Gyr).
ERA‐40 reanalysis hydrological applications in the characterization of regional drought
Authors: Dutra Emanuel , Viterbo Pedro , Miranda Pedro M. A.
Published: October 2008

The use of a land surface model (TESSEL) for drought characterization is proposed. The method is tested with the 1958–2001 ECMWF ERA‐40 reanalysis and its results are successfully compared with those obtained with other indices (SPI, PDSI) computed from observations in Iberia, a region highly vulnerable to drought. The proposed index, Normalized Soil Moisture (NSM), requires no local tuning, and, in principle, is readily computable from point observations, reanalysis, forecasts or climate scenarios. NSM from offline integrations has an enhanced consistency for drought analysis when compared with NSM computed directly from ERA‐40 soil moisture. Analysis of the NSM fields indicates that while the spatial heterogeneity of precipitation is the main driver of the spatial variability of drought, the spatial distribution of soil characteristics modulates its temporal variability. This suggests the need for better soil maps at the global scale.
An upward moving thin layer in the equatorial F region observed by a digisonde
Authors: Lee Chien‐Chih , Su Shin‐Yi , Reinisch Bodo W.
Published: October 2008

This study presents an observation of a thin layer motion in the equatorial F region for the first time. The thin layer is detected by the Jicamarca Digisonde from 1000 to 1230 LT (1500 to 1730 UT) on 14 October 1996. We apply the inversion and fitting processes to derive the parameters (peak density, peak height, scale heights) of a thin layer. Results show that the thin layer has a constant total content of 2.48 × 106 el/cm2 that might be formed by the long‐lived metallic ions. From 1000 to 1200 LT, the layer is lifted upward from 164.6 to 275.9 km height with a velocity of 15.5 m/s, where the topside and bottomside scale heights are 2.8–5.0 and 1.2–2.4 km, respectively. In addition to the characteristics of the thin layer, this observation further provides evidence for the vertical transport of metallic ions in the equatorial F region.
Water isotopes during the Last Glacial Maximum: New general circulation model calculations
Authors: Lee Jung‐Eun , Fung Inez , DePaolo Donald J. , Otto‐Bliesner Bette
Published: October 2008

The application of water isotopes to estimate the glacial‐interglacial cycle of temperature (T) assumes the validity of the present‐day spatial relationship between Ta and δ18O in precipitation (δ18Op) to estimate temporal changes of the temperature at a fixed location. We explored how and why the spatial relationship between annual mean Ta − δ18Op is different from the temporal relationship at one location. Our general circulation‐isotope model exhibits a spatial slope of 1.22‰/°C between annual mean temperature at the top of the inversion layer (Ti) and δ18Op over Antarctica, comparable to the observed value of 1.25‰/°C from Dahe et al. (1999) and using the Phillpot and Zillman (1970) relationship between surface temperature and the temperature of the inversion layer. Over the Southern Ocean (45°–60°S), local evaporation accounts for 50% of precipitation, and this evaporative flux (mean δ18Oe of ∼−1‰) increases the δ18O of vapor (mean δ18Ov of ∼−16‰). During the Last Glacial Maximum (LGM; 21,000 years ago), the isotopic composition of the vapor near the ice edge (∼60°S) is calculated to be similar to the present values because evaporative recharge also accounts for ∼50% of the precipitation over the Southern Ocean. As a result, the isotopic composition of vapor during the LGM is close to the present values at the ice edge. The apparent temporal slope over eastern Antarctica is half of the observed spatial slope. Our LGM experiment estimates an Antarctic mean annual temperature decrease of 13°C at Vostok, much larger than previous estimates. Our experiments with two specifications of LGM sea surface temperatures suggest that the value of the temporal slope is related to the temperature decrease over the Southern Ocean.
Historical isotope simulation using Reanalysis atmospheric data
Authors: Yoshimura K. , Kanamitsu M. , Noone D. , Oki T.
Published: October 2008

In this paper we present a multidecadal and global three‐dimensional stable water isotope data set. This is accomplished by incorporating processes of the stable water isotopes into an atmospheric general circulation model and by applying a spectral nudging technique toward Reanalysis dynamical fields. Unlike the global model simulations forced only by sea surface temperature (SST), the dynamical fields used in the simulation are never far from observation because the spectral nudging technique constrains large‐scale atmospheric circulation to that of observation, and therefore the simulated isotopic fields are reasonably accurate over the entire globe for daily to interannual time scales. As a case in point, it is revealed that the current approach reproduces the Arctic Oscillation much more correctly than the simulations forced only by SST, and consequently, the monthly isotopic variability better matches observations over midlatitudes to high latitudes in the Northern Hemisphere, especially Europe. This method is of great use in providing information in regions where in situ isotope observations are not available. Such information is required for a variety of biogeochemical, hydrological, and paleoclimate studies and as boundary and initial conditions for regional isotopic simulations.
Impact of efflux transporters and of seizures on the pharmacokinetics of oxcarbazepine metabolite in the rat brain
Authors: Clinckers R , Smolders I , Michotte Y , Ebinger G , Danhof M , Voskuyl R A , Pasqua O Della
Published: October 2008

Background and purpose:

Accurate prediction of biophase pharmacokinetics (PK) is essential to optimize pharmacotherapy in epilepsy. Here, we characterized the PK of the active metabolite of oxcarbazepine, 10,11‐dihydro‐10‐hydroxy‐carbamazepine (MHD) in plasma and in the hippocampus. Simultaneously, the impact of acute seizures and efflux transport mechanisms on brain distribution was quantified.

Experimental approach:

Rats received subtherapeutic and anticonvulsant doses of MHD in non‐epileptic conditions and during focal pilocarpine‐induced limbic seizures. To evaluate the effect of efflux transport blockade, a separate group received subtherapeutic doses combined with intrahippocampal perfusion of verapamil. Free plasma and extracellular hippocampal MHD concentrations were determined using microdialysis and liquid chromatography techniques. An integrated PK model describing simultaneously the PK of MHD in plasma and brain was developed using nonlinear mixed effects modelling. A bootstrap procedure and a visual predictive check were performed to assess model performance.

Key results:

A compartmental model with combined zero‐ and first‐order absorption, including lag time and biophase distribution best described the PK of MHD. A distributional process appeared to underlie the increased brain MHD concentrations observed following seizure activity and efflux transport inhibition, as reflected by changes in the volume of distribution of the biophase compartment. In contrast, no changes were observed in plasma PK.

Conclusions and implications:

Simultaneous PK modelling of plasma and brain concentrations has not been used previously in the evaluation of antiepileptic drugs (AEDs). Characterisation of biophase PK is critical to assess the impact of efflux transport mechanisms and acute seizures on brain disposition and, consequently, on AED effects.

British Journal of Pharmacology (2008) 155, 1127–1138; doi:10.1038/bjp.2008.366; published online 6 October 2008
Apolipoprotein(a) stimulates vascular endothelial cell growth and migration and signals through integrin αVβ3
Authors: Liu Lei , Craig Andrew W. , Meldrum Heather D. , Marcovina Santica M. , Elliott Bruce E. , Koschinsky Marlys L.
Published: October 2008

Elevated plasma concentrations of Lp(a) [lipoprotein(a)] are an emerging risk factor for atherothrombotic disease. Apo(a) [apolipoprotein(a)], the unique glycoprotein component of Lp(a), contains tandem repeats of a plasminogen kringle (K) IV-like domain. In the light of recent studies suggesting that apo(a)/Lp(a) affects endothelial function, we evaluated the effects of apo(a)/Lp(a) on growth and migration of cultured HUVECs (human umbilical-vein endothelial cells). Two full-length r-apo(a) [recombinant apo(a)] variants (12K and 17K), as well as Lp(a), were able to stimulate HUVEC growth and migration to a comparable extent; 17K r-apo(a) also decreased the levels of total and active transforming growth factor-β secreted by these cells. Using additional r-apo(a) variants corresponding to deletions and/or site-directed mutants of various kringle domains in the molecule, we were able to determine that the observed effects of full-length r-apo(a) on HUVECs were dependent on the presence of a functional lysine-binding site(s) in the apo(a) molecule. With respect to signalling events elicited by apo(a) in HUVECs, we found that 17K treatment of the cells increased the phosphorylation level of FAK (focal adhesion kinase) and MAPKs (mitogen-activated protein kinases), including ERK (extracellular-signal-regulated kinase), p38 and JNK (c-Jun N-terminal kinase). In addition, we showed that LM609, the function-blocking antibody to integrin αVβ3, abrogated the effects of 17K r-apo(a) and Lp(a) on HUVECs. Taken together, the results of the present study suggest that the apo(a) component of Lp(a) signals through integrin αVβ3 to activate endothelial cells.
A chimaeric glutamyl:glutaminyl-tRNA synthetase: implications for evolution
Authors: Saha Rajesh , Dasgupta Saumya , Basu Gautam , Roy Siddhartha
Published: October 2008

aaRSs (aminoacyl-tRNA synthetases) are multi-domain proteins that have evolved by domain acquisition. The anti-codon binding domain was added to the more ancient catalytic domain during aaRS evolution. Unlike in eukaryotes, the anti-codon binding domains of GluRS (glutamyl-tRNA synthetase) and GlnRS (glutaminyl-tRNA synthetase) in bacteria are structurally distinct. This originates from the unique evolutionary history of GlnRSs. Starting from the catalytic domain, eukaryotic GluRS evolved by acquiring the archaea/eukaryote-specific anti-codon binding domain after branching away from the eubacteria family. Subsequently, eukaryotic GlnRS evolved from GluRS by gene duplication and horizontally transferred to bacteria. In order to study the properties of the putative ancestral GluRS in eukaryotes, formed immediately after acquiring the anti-codon binding domain, we have designed and constructed a chimaeric protein, cGluGlnRS, consisting of the catalytic domain, Ec GluRS (Escherichia coli GluRS), and the anti-codon binding domain of EcGlnRS (E. coli GlnRS). In contrast to the isolated EcN-GluRS, cGluGlnRS showed detectable activity of glutamylation of E. coli tRNAglu and was capable of complementing an E. coli ts (temperature-sensitive)-GluRS strain at non-permissive temperatures. Both cGluGlnRS and EcN-GluRS were found to bind E. coli tRNAglu with native EcGluRS-like affinity, suggesting that the anticodon-binding domain in cGluGlnRS enhances kcat for glutamylation. This was further confirmed from similar experiments with a chimaera between EcN-GluRS and the substrate-binding domain of EcDnaK (E. coli DnaK). We also show that an extended loop, present in the anticodon-binding domains of GlnRSs, is absent in archaeal GluRS, suggesting that the loop was a later addition, generating additional anti-codon discrimination capability in GlnRS as it evolved from GluRS in eukaryotes.