bluuebunny/crossref_metadata_2025 huggingface dataset:
U–Th–Pb ages of single zircons in Archaean supracrustals from Nain Province, Labrador, Canada
Authors: Schiøtte L. , Compston W. , Bridgwater D.
Published: October 2008

Ion-probe U–Pb dating of igneous zircons from an acid metavolcanite belonging to the Nulliak supracrustal association of the Saglek area, northern Labrador, suggests an original age of 3776 ± 8 Ma (2σ), interpreted as the deposition age of the volcanite. In accordance with the field model, this is slightly but significantly older than the previously obtained ion-probe U–Pb age of igneous zircons from the main phase of the Uivak gneisses, which carries inclusions of the supracrustal association. A secondary event of zircon growth recorded in the metavolcanite has a maximum age of 3065 ± 8 Ma (2σ).A metapelite belonging to the Weekes amphibolite supracrustal association of the Hopedale area south of Nain contains rounded, low-U zircons of 3258 ± 24 Ma (2σ) age. Occasional textural evidence suggests that some of these zircons are most likely detrital grains of igneous origin, in which case 3258 ± 24 Ma is a minimum age of the source from which the sediment was derived and a maximum age for the deposition of the sediment. However, the possibility that the age represents recrystallization of the sediment under high-grade conditions cannot be ruled out. A 2841 ± 5 Ma (2σ) age obtained on a younger generation of euhedrally zoned high-U zircons from the metapelite is within error of the published bulk zircon U–Pb age of the tonalitic component of the Kanairiktok plutonic suite that intrudes the older orthogneiss and supracrustal units in the area. These younger zircons are most likely to have grown during migmatization of the metasediment at the time of emplacement of the suite.The zircon data give no positive evidence to support correlation between the Nulliak supracrustals and the Weekes amphibolite association.
Th–U disequilibrium dating of Middle and Late Pleistocene wood and shells from Banks and Victoria islands, Arctic Canada
Authors: Causse C. , Vincent J. -S.
Published: October 2008

An attempt has been made at dating Middle and Late Pleistocene deposits from Banks and Victoria islands using the Th–U disequilibrium method. Geological correlations are difficult to establish because of the discontinuous nature of the terrestrial units and the relative absence of datable fossil wood and shells. The Th–U geochemical system likely remained closed for extended periods because of the presence of permafrost, which implies very limited or absent water circulation. The Th–U age determinations obtained confirmed the previously established stratigraphic framework and provide chronological information in that samples of Sangamonian age are differentiated from those that are younger (Wisconsinan and Holocene) or older (Middle Pleistocene). The Th–U disequilibrium method carefully used in areas where water circulation is limited can thus provide chronological control for sediments older than those that can be dated by the radiocarbon method.
Sm–Nd isochron from a granodiorite–granite complex in the Portman Lake region, Northwest Territories
Authors: Stevenson Ross K. , Patchett P. J. , Martin R. F.
Published: October 2008

Whole-rock samples for a granodiorite–granite intrusion in the Portman Lake area of the Northwest Territories yield an Sm–Nd isochron with an age of 2577 ± 36 Ma. The addition of a garnet analysis results in an age of 2562 ± 21 Ma. An Sm–Nd isochron is rare for granitic samples because of small ranges in 147Sm/144Nd values and variability in the initial Nd isotopic ratios. A wide range in 147Sm/144Nd values among samples in this study is considered a result of garnet fractionation and (or) variable concentrations of titanite in the samples. The εNd values for the initial Nd isotopic ratios of the isochrons are essentially zero or bulk Earth values. The evolution of the intrusion at 2.56 Ga reflects either the remelting of (2.7–2.8 Ga) preexisting continental crust or the mixing of depleted mantle material and crust older than 2.8 Ga. In either case, the data argue for a crustal history of at least 200 Ma prior to the intrusion of the complex in this section of the Churchill Province.
Metal uptake and Fe-, Ti-oxide biomineralization by acidophilic microorganisms in mine-waste environments, Elliot Lake, Canada
Authors: Mann H. , Fyfe W. S.
Published: October 2008

Acidic effluent containing enhanced concentrations of toxic heavy metals discharges from a cumulative total of 104 ha of mine-tailings waste in Canada. Communities of acidophilic microorganisms, specifically the unicellular alga Euglena sp. and bacteria, thrive in many of the hostile, low-pH effluent environments, which are otherwise devoid of life. The micro organisms concentrate aqueous dissolved metals onto cell walls and at intracellular sites, during the life cycle, and strongly bind metals during early diagenesis. A sequence is observed in which amorphous Fe and Ti concentrated at cell walls are progressively transformed to microcrystalline aggregates of goethite, ferrihydrite, maghemite, magnetite, haematite, lepidocrocite, and ilmenite. The bioprecipitated Ti- and Fe-oxides and oxyhydroxides act as scavengers for heavy metals such as Cu, Pb, Zn, Ni, Cd, and Th. Acidophilic microorganisms play a central role in the toxic-metal budget of mine-tailings waste by efficiently sequestering aqueous metals and by promoting nucleation of oxide minerals whose inorganic formation is kinetically inhibited, thereby retarding toxic-metal dispersion into the natural environment.
Geochemistry of Late Proterozoic basaltic rocks from southeastern Cape Breton Island, Nova Scotia
Authors: Dostal J. , Keppie J. D. , Murphy J. B.
Published: October 2008

Late Proterozoic volcanic rocks of the Fourchu Group from the Avalon Zone in southeastern Cape Breton Island, Nova Scotia, are composed predominantly of mafic and felsic types with subordinate intermediate units that were all affected by subgreenschist- to greenschist-facies metamorphism. The rocks crop out in four fault blocks (Coastal, Stirling, East Bay Hills, and Coxheath) and have geochemical characteristics of ensialic orogenic volcanic suites. The basaltic rocks range from tholeiitic to calc-alkaline and show a distinct compositional zonation that resembles the across-arc variation observed in recent volcanic-arc systems. The variations include a progressive increase in abundances of light rare-earth elements, Th, Zr, Hf, Nb, and Ta and in the ratios of Zr/SiO2, Th/SiO2, Zr/Y, La/Yb, and Th/Hf from the Coastal block in the southeast to the Coxheath block in the northwest. The zonation may be explained in terms of a northwesterly-dipping subduction zone, with the trench lying to the southeast of Nova Scotia.
The Weekend dykes, a newly recognized mafic dyke swarm on the eastern shore of Nova Scotia, Canada
Authors: Ruffman Alan , Greenough John D.
Published: October 2008

A group of related mafic dykes is present along the eastern shore of Nova Scotia from Halifax to Country Harbour. The dykes are generally vertical, strike about 150°, and have an abundance of carbonate, apatite, and hydrous mafic minerals, indicating that the dykes may have formed from an alkaline (lamprophyric) magma. They postdate the Acadian folding of the Cambro-Ordovician Meguma Group metasedimentary rocks but predate Carboniferous faulting. Abundant exotic gneissic and (meta)plutonic xenoliths, representing probable pre-Meguma Group rocks, are found in half of the presently known dykes.The dykes may have formed in a regional tensional field during a shearing event synchronous with docking between the Meguma and Avalonian terranes or in a more local radial stress field around an igneous body, such as the Bog Island Lake or Ten Mile Lake diatreme in the Liscomb Complex. Similar ages suggest that the dykes may be related to the intrusion of the Devono-Carboniferous granites of the Musquodoboit batholith.
Les Plourdosteidae fam. nov. (Placodermi, Arthrodira) et leurs relations phylétiques au sein des Brachythoraci
Authors: Vézina Daniel
Published: October 2008

The study of Plourdosteus canadensis (Brachythoraci, Placodermi) from the Escuminac Formation (Frasnian) led us to erect a new family: the Plourdosteidae. Firstly, we discuss all the characteristics that allowed Ørvig to differentiate the genus Plourdosteus from Coccosteus. It is proposed to consider Plourdosteus mironovi as a synonym of Plourdosteus trautscholdi, found in the Baltic region of the USSR. The characteristics that support the monophyly of the Plourdosteidae are listed and are represented on a phylogenetic diagram. In the conclusion, the Dunkleosteidea sup. fam. nov., the Plourdosteidae fam. nov., and the type species Plourdosteus canadensis are defined. The different species of Plourdosteus are also listed.
The thermal regime of a permafrost body at Mont du Lac des Cygnes, Quebec
Authors: Allard Michel , Fortier Richard
Published: October 2008

A low peat plateau in the alpine forest–tundra at Mont du Lac des Cygnes, 100 km northeast of Québec City, contains a permafrost body 2 m thick. At an elevation of 960 m, this is the southernmost known occurrence of alpine permafrost in eastern Canada. The terrain over the permafrost is windblown and bears a very thin and discontinuous snow cover. One year of continuous temperature records indicates that the mean annual air temperature at this site is about −1.3 °C. The permafrost remains at temperatures very near the freezing point for most of the year.
Cover gneisses of the Monashee Terrane: a record of synsedimentary rifting in the North American Cordillera
Authors: Scammell Robert J. , Brown Richard L.
Published: October 2008

The Monashee Terrane of southeastern British Columbia is composed of Lower Proterozoic basement gneisses unconformably overlain by cover gneisses. The latter constitute a thick (> 2000 m) and laterally extensive (> 150 km) upper-amphibolite-grade succession of metasedimentary rocks, locally intercalated with minor intrusive and extrusive units. This succession is interpreted as reflecting initial broad, amagmatic subsidence and sedimentation on a cratonic platform (basement gneisses), most likely of North American affinity. Throughout most of the terrane, syndepositional magmatism is first marked by a laterally extensive (> 100 km) stratiform pyroclastic carbonatite, which is part of intermittent (long-lived?) alkaline magmatism. One alkaline body was intruded at ca. 740 ± 36 Ma (U–Pb zircon), suggesting that it may be part of initial Windermere rifting. Post-pyroclastic-carbonatite syndepositional extensional tectonism is further evidenced at the north end of the terrane by interlayered mature and immature siliciclastic sediments, with rapid facies changes, intercalated with ultramafic and mafic sills and flows, plus minor felsic pyroclastic deposits. All of these later deposits lie above stratigraphy correlated with strata hosting a stratiform Pb–Zn deposit with an Early Cambrian galena Pb-isotope age and, therefore, may be correlative with a rift–drift transition recorded in Hamill Group strata to the east. Rift tectonism recorded in cover gneisses may reflect one or more documented rift and rift–drift events recorded in Upper Proterozoic to Lower Cambrian strata of the western North American continental terrace prism.
Comparison of isotope stages 1–61 with the Baoji-type pedostratigraphic section of north-central China
Authors: Rutter Nat , Ding Zhongli , Liu Tungsheng
Published: October 2008

Until now, comparisons between terrestrial and marine proxy climatic records have been achieved successfully only for the last 1.2 Ma or back to oxygen isotope stage 36. The Baoji loess–paleosol section of north-central China possesses 37 field-identifiable paleosols and 37 loess units representing a time span of about 2.5 Ma. The Baoji section is judged by the authors to be the most complete pedostratigraphic sequence in north-central China. This section, coupled with recent success in correlating isotope records back to stage 63, or approximately 1.88 Ma, has enabled a more detailed comparison over a longer time span. Using magnetic reversals as markers, the records are shown to have nearly equal numbers of identifiable warm and cold periods during the last 1.8 Ma. In addition, although there are exceptions, data sets reveal similar patterns during the same time intervals, indicating climatic events on a global scale.
U–Pb ages and Sm–Nd signature of two subsurface granites from the Fort Simpson magnetic high, northwest Canada
Authors: Villeneuve M. E. , Thériault R. J. , Ross G. M.
Published: October 2008

Two undeformed biotite granites recovered from exploratory hydrocarbon drill holes that penetrated basement in the Fort Simpson magnetic high were analyzed for U–Pb zircon geochronology and Sm–Nd isotopic composition. Both samples give crystallization ages of 1845 Ma, with errors of less than 5 Ma. This age overlaps with the waning stages of magmatism in the Great Bear magmatic zone of Wopmay Orogen, 200 km to the east. One sample has an initial εNd of +1.3 and a TDM of 2.14 Ga, whereas the other yielded an initial εNd of −2.1 and a TDM of 2.45 Ga. The latter sample indicates that Early Proterozoic light rare-earth element enriched lithosphere with a crustal history dating back to at least 2.45 Ga is present in the subsurface west of Wopmay Orogen.
Geochemical variations in Middle Ordovician volcanic rocks of the northern Miramichi Highlands and their tectonic significance
Authors: Staal C. R. Van , Winchester J. A. , Bédard J. H.
Published: October 2008

A detailed geochemical study of Middle Ordovician volcanic rocks, undertaken in the northern Miramichi Highlands of New Brunswick, shows that 10 basaltic suites can be distinguished. These suites are assigned to the Tetagouche and Fournier groups. The contact between these two groups is a major thrust zone, marked for over 70 km by a prominent blueschist zone. All the Tetagouche Group volcanic rocks have chemistries consistent with extrusion in a continental rift, but most Fournier Group basalts in the Miramichi Highlands have chemistries suggestive of an oceanic back-arc setting. The chemical signatures, stratigraphic variations, and structural data indicate that the northern Miramichi Highlands preserve a section across a telescoped Middle Ordovician back-arc basin that initially opened as a result of asthenospheric injection near the rear part of a Lower Ordovician ensialic arc.
Structure of the Early Proterozoic Hurwitz Group in the Tavani area, Keewatin, Northwest Territories
Authors: Park Adrian F. , Ralser Steven
Published: October 2008

A structural study of the Early Proterozoic Hurwitz Group has been carried out in the Tavani area, approximately 80 km southwest of Rankin Inlet, District of Keewatin, Northwest Territories. The Hurwitz Group, in the Tavani area, consists of orthoquartzites of the Kinga Formation (Whiterock Lake Member) and quartz-feldspar arenites and litharenites of the Tavani Formation. More localized lithologies include siltstone, sandstones, breccia, and shales beneath the Whiterock Lake Member and conglomerate, shales, and shale-clast breccias within the Tavani Formation.Open, northeast-trending folds dominate the Hurwitz Group, although overturned folds and easterly trending structures are developed locally. Later northwest-trending faults complicate the northeast-trending structural pattern. Three structural domains are defined: north of the Wilson River, the Whiterock Syncline, and the Last Lake belt. The interrelationship of folding and faulting creates distinctive patterns in each domain, though overall, folding is demonstrated to be a local response to basement faulting, including reactivation of Archean structures. An overall north–south compressive regime is envisaged in which heterogeneities in the Archean basement are responsible for local peculiarities.
Évolution paléogéographique de la marge nord-ouest de l'Afrique du Cambrien à la fin du Carbonifère (du Maroc au Libéria)
Authors: Villeneuve Michel , Cornée Jean-Jacques
Published: October 2008

Paleogeographic reconstructions of Paleozoic time are presented for the northwest margin of the West-African Craton. An extensional regime and a marine transgression were dominant during the Early Cambrian. During the Middle Cambrian, the Rokélides orogen was responsible for the sea regression to the south, while the proto-Atlantic opening was active to the north of the Reguibat shield. A large stable marine platform was present during Early and Middle Ordovician. A general regression and the formation of the West-African Inlandsis took place during the Late Ordovician. During Silurian time, this sea transgressed over most of the African platform. Incipient Hercynian deformations during the Early Devonian produced horsts and grabens in Morocco. At the end of the Devonian and the beginning of the Carboniferous, the sea was restricted to isolated basins and tectonic trenches. Collision between West Africa and North America during the Late Carboniferous transformed the Lower Paleozoic margin into an Hercynian orogenic belt, whose structure is controlled by the presence of crustal blocks, generated as early as the Cambrian, and probably reflecting, in turn, older Panafrican zones of weakness. [Translated by the Journal]
NULL ENERGY CONDITION AND DARK ENERGY MODELS
Authors: QIU TAOTAO , CAI YI-FU , ZHANG XINMIN
Published: October 2008

Null Energy Condition (NEC) requires the equation of state (EoS) of the universe wu satisfy wu ≥ -1, which implies, for instance in a universe with matter and dark energy dominating wu = w m Ω m + w de Ω de = w de Ω de ≥ -1. In this paper we study constraints on the dark energy models from the requirement of the NEC. We will show that with Ω de ~ 0.7, w de < -1 at present epoch is possible. However, NEC excludes the possibility of w de < -1 forever as happened in the Phantom model, but if w de < -1 stays for a short period of time as predicted in the Quintom theory, NEC can be satisfied. We take three examples of Quintom models of dark energy, namely the phenomenological EoS, the two-scalar-field model and the single scalar model with a modified Dirac–Born–Infeld (DBI) Lagrangian to show how this happens.
MODELING NONLINEAR GENE REGULATORY NETWORKS FROM TIME SERIES GENE EXPRESSION DATA
Authors: FUJITA ANDRÉ , SATO JOÃO RICARDO , GARAY-MALPARTIDA HUMBERTO MIGUEL , SOGAYAR MARI CLEIDE , FERREIRA CARLOS EDUARDO , MIYANO SATORU
Published: October 2008

In cells, molecular networks such as gene regulatory networks are the basis of biological complexity. Therefore, gene regulatory networks have become the core of research in systems biology. Understanding the processes underlying the several extracellular regulators, signal transduction, protein–protein interactions, and differential gene expression processes requires detailed molecular description of the protein and gene networks involved. To understand better these complex molecular networks and to infer new regulatory associations, we propose a statistical method based on vector autoregressive models and Granger causality to estimate nonlinear gene regulatory networks from time series microarray data. Most of the models available in the literature assume linearity in the inference of gene connections; moreover, these models do not infer directionality in these connections. Thus, a priori biological knowledge is required. However, in pathological cases, no a priori biological information is available. To overcome these problems, we present the nonlinear vector autoregressive (NVAR) model. We have applied the NVAR model to estimate nonlinear gene regulatory networks based entirely on gene expression profiles obtained from DNA microarray experiments. We show the results obtained by NVAR through several simulations and by the construction of three actual gene regulatory networks (p53, NF-κB, and c-Myc) for HeLa cells.
OBJECTIVE EVALUATION MEASURES OF GENETIC MARKER SELECTION IN LARGE-SCALE SNP GENOTYPING
Authors: KAMINUMA ELI , MASUYA HIROSHI , MIURA IKUO , MOTEGI HIROMI , TAKAHASI KENZI R. , NAKAZAWA MIKI , MATSUI MINAMI , GONDO YOICHI , NODA TETSUO , SHIROISHI TOSHIHIKO , WAKANA SHIGEHARU , TOYODA TETSURO
Published: October 2008

High-throughput single nucleotide polymorphism (SNP) genotyping systems provide two kinds of fluorescent signals detected from different alleles. In current technologies, the process of genotype discrimination requires subjective judgments by expert operators, even when using clustering algorithms. Here, we propose two evaluation measures to manage fluorescent scatter data with nonclear plot aggregation. The first is the marker ranking measure, which provides a ranking system for the SNP markers based on the distance between the scatter plot distribution and a user-defined ideal distribution. The second measure, called individual genotype membership, uses the membership probability of each genotype related to an individual plot in the scatter data. In verification experiments, the marker ranking measure determined the ranking of SNP markers correlated with the subjective order of SNP markers judged by an expert operator. The experiment using the individual genotype membership measure clarified that the total number of unclassified individuals was remarkably reduced compared to that of manually unclassified ones. These two evaluation measures were implemented as the GTAssist software. GTAssist provides objective standards and avoids subjective biases in SNP genotyping workflows.
KINETIC MODELING OFACEOPERON GENETIC REGULATION INESCHERICHIA COLI
Authors: PESKOV KIRILL , GORYANIN IGOR , PRANK KLAUS , TOBIN FRANK , DEMIN OLEG
Published: October 2008

A family of kinetic models has been developed that takes into account available experimental information on the regulation of ace operon expression in Escherichia coli. This has allowed us to study and analyze possible versions of regulation of the ace operon and to test their possibilities. Based on literature analysis, we found that there is an ambiguity of properties of IclR (main repressor of ace operon). The main aspect of this ambiguity are two different forms of IclR purified from E. coli K strain and different coeffector sets for IclR purified from E. coli K and B strains. It has been shown that the full-length form of IclR is physiologically relevant and that IclR truncation is a result of purification of the protein from E. coli K strains. We also found that the IclR protein purified from E. coli B strain carries two coeffector binding sites. Using model-developed levels of steady state aceBAK expression against physiological ranges of coeffectors, concentration has been predicted.
LONG-RANGE INFORMATION AND PHYSICALITY CONSTRAINTS IMPROVE PREDICTED PROTEIN CONTACT MAPS
Authors: MARTIN ALBERTO J. M. , BAÙ DAVIDE , VULLO ALESSANDRO , WALSH IAN , POLLASTRI GIANLUCA
Published: October 2008

Protein topology representations such as residue contact maps are an important intermediate step towards ab initio prediction of protein structure, but the problem of predicting reliable contact maps is far from solved. One of the main pitfalls of existing contact map predictors is that they generally predict unphysical maps, i.e. maps that cannot be embedded into three-dimensional structures or, at best, violate a number of basic constraints observed in real protein structures, such as the maximum number of contacts for a residue. Here, we focus on the problem of learning to predict more "physical" contact maps. We do so by first predicting contact maps through a traditional system (XXStout), and then filtering these maps by an ensemble of artificial neural networks. The filter is provided as input not only the bare predicted map, but also a number of global or long-range features extracted from it. In a rigorous cross-validation test, we show that the filter greatly improves the predicted maps it is input. CASP7 results, on which we report here, corroborate this finding. Importantly, since the approach we present here is fully modular, it may be beneficial to any other ab initio contact map predictor.
SPONSORSHIP, COMMUNITY, AND SOCIAL CAPITAL RESOURCES IN INDIGENOUS COMMUNITIES
Authors: SWINNEY JANE
Published: October 2008

This exploratory study conducted in heavily indigenous communities was undertaken to investigate entrepreneurial perceptions of community (sense of place, image, and positioning) and social capital (reciprocity, shared vision, and density of networks) resources present in rural communities, and the sponsorship involvement of the entrepreneurs in community activities. The uniqueness of the study was its focus on indigenous communities with a higher than state average Native-American population. Previous work highlighting the collective nature and attitudes of Native Americans was not supported for the entrepreneurs in this study. Indigenous entrepreneurs were those who identified their ethnicity as Native American and majority entrepreneurs were those who identified their ethnicity as white. For indigenous entrepreneurs, there were no significant correlations among social capital resources or community resources and sponsorship. For majority entrepreneurs, all three social capital resources correlated significantly with sponsorship, and none of the community resources correlated significantly with sponsorship. The correlation between image and sponsorship was statistically significant for the total sample (n = 149).

Mean scores to each of the social capital and community resources were calculated. Positioning was the resource with the lowest mean score. The positioning statement differentiates one downtown from a competing downtown and is indicative of how the downtown wants to be perceived. The findings point to the need for economic development officials to strengthen community positioning through an improved understanding and acceptance of the community's position statement by business owners in the community.
SEGMENTING THE POPULATION OF ENTREPRENEURS: A CLUSTER ANALYSIS STUDY
Authors: CARDON MELISSA S. , SHINNAR RACHEL S. , EISENMAN MICKI , ROGOFF EDWARD G.
Published: October 2008

This paper contributes to our understanding of minority entrepreneurs in the US by showing that ethnicity alone should not be used to describe or categorize small business owners. We examine a sample of 508 entrepreneurs from three minority groups (African, Mexican, and Korean Americans) and a white group using cluster analysis to explore a categorization pattern that best describes the differences among these entrepreneurs. Our findings suggest that minority entrepreneurs are in fact a very heterogeneous group on a multitude of dimensions such as motivations for entry, satisfaction with the business, nature of problems experienced, and demographics of the business such as its size and gross income. Based on our findings, we recommend that educational and support programs targeting minority entrepreneurs should consider other variables rather than focusing on ethnicity alone.
REPRESENTATIONS OF INTEGERS BY THE FORM x2 + xy + y2 + z2 + zt + t2
Authors: CHAPMAN ROBIN
Published: October 2008

We give an elementary proof of the number of representations of an integer by the quaternary quadratic form x2 + xy + y2 + z2 + zt + t2.
ON THE HARDY–LITTLEWOOD PROBLEM IN SHORT INTERVALS
Authors: LANGUASCO ALESSANDRO , ZACCAGNINI ALESSANDRO
Published: October 2008

We study the distribution of Hardy–Littlewood numbers in short intervals both unconditionally and conditionally, i.e. assuming the Riemann Hypothesis (RH). We prove that a suitable average of the asymptotic formula for the number of representations of a Hardy–Littlewood number holds in the interval [n, n + H], where H < X1-1/k+∊ and n ∈ [X, 2X].
BEHAVIOR OF SOME GENERALIZED MULTIPLE SINE FUNCTIONS
Authors: ONODERA KAZUHIRO
Published: October 2008

Our aim is to investigate the behavior of generalized multiple sine functions with general period parameters in the fundamental domain. For that, we need to calculate the number of their extremal values. By estimating their special values, we determine it in some cases including the quintuple sine function. As a consequence, we sketch their graphs.
ON CURVES OVER FINITE FIELDS WITH JACOBIANS OF SMALL EXPONENT
Authors: FORD KEVIN , SHPARLINSKI IGOR
Published: October 2008

We show that finite fields over which there is a curve of a given genus g ≥ 1 with its Jacobian having a small exponent, are very rare. This extends a recent result of Duke in the case of g = 1. We also show that when g = 1 or g = 2, our lower bounds on the exponent, valid for almost all finite fields 𝔽qand all curves over 𝔽q, are best possible.
A p-ADIC LIMIT OF SIEGEL–EISENSTEIN SERIES OF PRIME LEVEL q
Authors: MIZUNO YOSHINORI
Published: October 2008

We show that a p-adic limit of a Siegel–Eisenstein series of prime level q becomes a Siegel modular form of level pq. This paper contains a simple formula for Fourier coefficients of a Siegel–Eisenstein series of degree two and prime levels.
HYPERGEOMETRIC BERNOULLI POLYNOMIALS AND APPELL SEQUENCES
Authors: HASSEN ABDUL , NGUYEN HIEU D.
Published: October 2008

There are two analytic approaches to Bernoulli polynomials Bn(x): either by way of the generating function zexz/(ez - 1) = ∑ Bn(x)zn/n! or as an Appell sequence with zero mean. In this article, we discuss a generalization of Bernoulli polynomials defined by the generating function zN exz/(ez - TN-1(z)), where TN(z) denotes the Nth Maclaurin polynomial of ez, and establish an equivalent definition in terms of Appell sequences with zero moments in complete analogy to their classical counterpart. The zero-moment condition is further shown to generalize to Bernoulli polynomials generated by the confluent hypergeometric series.
ON THE PROBLEM OF INTEGER SOLUTIONS TO DECOMPOSABLE FORM INEQUALITIES
Authors: LIU YUANCHENG
Published: October 2008

This paper proves a conjecture proposed by Chen and Ru in [1] on the finiteness of the number of integer solutions to decomposable form inequalities. Let k be a number field and let F(X1,…,Xm) be a non-degenerate decomposable form with coefficients in k. We show that for every finite set of places S of k containing the archimedean places of k, for each real number λ < 1 and each constant c > 0, the inequality [Formula: see text] has only finitely many [Formula: see text]-non-proportional solutions, where HS(x1,…,xm) = Πυ∈S max 1≤i≤m ||xi||υ is the S-height.
Serum amyloid A induces endothelial dysfunction in porcine coronary arteries and human coronary artery endothelial cells
Authors: Wang Xinwen , Chai Hong , Wang Zehao , Lin Peter H. , Yao Qizhi , Chen Changyi
Published: October 2008

The objective of this study was to determine the effects and mechanisms of serum amyloid A (SAA) on coronary endothelial function. Porcine coronary arteries and human coronary arterial endothelial cells (HCAECs) were treated with SAA (0, 1, 10, or 25 μg/ml). Vasomotor reactivity was studied using a myograph tension system. SAA significantly reduced endothelium-dependent vasorelaxation of porcine coronary arteries in response to bradykinin in a concentration-dependent manner. SAA significantly decreased endothelial nitric oxide (NO) synthase (eNOS) mRNA and protein levels as well as NO bioavailability, whereas it increased ROS in both artery rings and HCAECs. In addition, the activities of internal antioxidant enzymes catalase and SOD were decreased in SAA-treated HCAECs. Bio-plex immunoassay analysis showed the activation of JNK, ERK2, and IκB-α after SAA treatment. Consequently, the antioxidants seleno-l-methionine and Mn(III) tetrakis-(4-benzoic acid)porphyrin and specific inhibitors for JNK and ERK1/2 effectively blocked the SAA-induced eNOS mRNA decrease and SAA-induced decrease in endothelium-dependent vasorelaxation in porcine coronary arteries. Thus, SAA at clinically relevant concentrations causes endothelial dysfunction in both porcine coronary arteries and HCAECs through molecular mechanisms involving eNOS downregulation, oxidative stress, and activation of JNK and ERK1/2 as well as NF-κB. These findings suggest that SAA may contribute to the progress of coronary artery disease.
Acidic reoxygenation protects against endothelial dysfunction in rat aortic rings submitted to simulated ischemia
Authors: López Diego , Rodríguez-Sinovas Antonio , Agulló Luis , Inserte Javier , Cabestrero Alberto , García-Dorado David
Published: October 2008

Ischemia-reperfusion causes endothelial dysfunction. Prolongation of acidosis during initial cardiac reperfusion limits infarct size in animal models, but the effects of acidic reperfusion on vascular function are unknown. The present work analyzes the effects of acidic reoxygenation on vascular responses to different agonists in rat aortic rings. Arterial rings obtained from Sprague-Dawley rat aorta were placed in organ baths containing a Krebs solution oxygenated at 37°C (pH 7.4). After equilibration (30 mN, 1 h), the effects of acidosis (pH 6.4) on aortic responses to acetylcholine and norepinephrine were initially assessed under normoxic conditions. Thereafter, the effects of acidosis during hypoxia (1 h) or reoxygenation on aortic responses to acetylcholine, norepinephrine, or sodium nitroprusside were analyzed and compared with those observed in control rings. Acidosis did not modify aortic responses to acetylcholine or adrenaline during normoxia. In contrast, rings submitted to hypoxia and reoxygenated at pH 7.4 showed a reduction in vasodilator responses to acetylcholine and in contractions to norepinephrine with no change in responses to sodium nitroprusside. Reoxygenation at pH 6.4 did not modify the depressed response to norepinephrine but enhanced the recovery of acetylcholine-induced vasorelaxation. Cumulative concentration-response curves to acetylcholine showed an increased responsiveness to this drug in rings reoxygenated at a low pH. This functional improvement was associated with the preservation of aortic cGMP content after stimulation of reoxygenated rings with acetylcholine. In conclusion, acidic reoxygenation preserves endothelial function in arterial rings submitted to simulated ischemia, likely through the preservation of cGMP signaling.
Role of multidrug resistance-associated protein 1 in the pathogenesis of allergic airway inflammation
Authors: Yoshioka Masakata , Sagara Hironori , Takahashi Fumiyuki , Harada Norihiro , Nishio Kazuto , Mori Akio , Ushio Hiroko , Shimizu Kazue , Okada Takenori , Ota Mayumi , Ito Yoichi M. , Nagashima Osamu , Atsuta Ryo , Suzuki Toshihiro , Fukuda Takeshi , Fukuchi Yoshinosuke , Takahashi Kazuhisa
Published: October 2008

Multidrug resistance-associated protein 1 (MRP1) is a cysteinyl leukotriene (CysLT) export pump expressed on mast cells. CysLTs are crucial mediators in allergic airway disease. However, biological significance of MRP1 in allergic airway inflammation has not yet been elucidated. In this study, we sensitized wild-type control mice ( mrp1+/+) and MRP1-deficient mice ( mrp1−/−) to ovalbumin (OVA) and challenged them with OVA by aerosol. Airway inflammation and goblet cell hyperplasia after OVA exposure were reduced in mrp1−/− mice compared with mrp1+/+ mice. Furthermore, CysLT levels in bronchoalveolar lavage fluid (BALF) from OVA-exposed mrp1−/− mice were significantly lower than those from OVA-exposed mrp1+/+ mice. Levels of OVA-specific IgE, IL-4, and IL-13 in BALF were also decreased in OVA-exposed mrp1−/− mice. IgE-mediated release of CysLTs from murine bone marrow-derived mast cells was markedly impaired by MRP1 deficiency. Our results indicate that MRP1 plays an important role in the development of allergic airway inflammation through regulation of IgE-mediated CysLT export from mast cells.
Performance of Equal Power Allocation in Multiuser OFDM‐Based Cognitive Radio Systems
Authors: Zhang Yonghong , Leung Cyril
Published: October 2008

The performance difference between a simple equal subchannel
power allocation and the optimal water‐filling subchannel
power allocation schemes is studied for a multiuser OFDM‐based
cognitive radio (CR) system. It is shown that this difference
depends on the average subchannel gain variations among
the CR users as well as the activity levels of the primary users.
Ka Band Phase Locked Loop Oscillator Dielectric Resonator Oscillator for Satellite EHF Band Receiver
Authors: Coco S. , Di Maggio F. , Laudani A. , Pomona I.
Published: October 2008

This paper describes the design and fabrication of a Ka Band PLL DRO having a fundamental oscillation frequency of 19.250 GHz, used as local oscillator in the low-noise block of a down converter (LNB) for an EHF band receiver. Apposite circuital models have been created to describe the behaviour of the dielectric resonator and of the active component used in the oscillator core. The DRO characterization and measurements have shown very good agreement with simulation results. A good phase noise performance is obtained by using a very highQdielectric resonator.
A Compact Wideband Stacked Antenna for the Tri-Band GPS Applications
Authors: Abd Elrazzak Maher M. , Alsharekh M. F.
Published: October 2008

A compact wideband stacked patch antenna is presented for the applications of GPS systems. This antenna covers the L1, L2, and L5 GPS bands of operating frequencies 1.575, 1.227, and 1.176 GHz, respectively. High permittivity dielectric materials are used to minimize the antenna dimensions. The obtained antenna is of dimensions  mm. To verify the design, the time dependence field distribution, the scattering parameters, and the radiation pattern are presented. The scattering parameters show that the antenna operates at the GPS frequencies with lower than  dB. The finite difference time domain (FDTM) with the perfect matched layer (PML) is used in the present analysis.
Evaluation of Short-Term Psychological Functions in Opiate Addicts after Ablating the Nucleus Accumbens via Stereotactic Surgery
Authors: He Fei , Guan Hao , Zhao Zhijing , Miao Xinfang , Zhou Qin , Li Lihong , Huang Dongmei , Liu Anheng , Miao Danmin
Published: October 2008

Objective: To investigate the short-term psychological function of opiate addicts who have undergone ablative stereotactic surgery targeting the nucleus accumbens (NAc) for alleviating opiate drug psychological dependence. Methods: The psychological functional status of 14 opiate addicts was assessed by standardized psychological tests both before and approximately 3 months after stereotactic surgery. Standardized tests included the Wechsler Adult Intelligence Scale-Revised Chinese (WAIS-RC), the Clinical Memory Scale of Chinese (CMS), the Eysenck Personality Questionnaire (EPQ) and the Symptom Checklist 90 (SCL-90). The evaluation of psychological dimensions included intelligence, memory, personality characteristics and mental health symptoms. Results: Compared with the preoperative state, there was no statistically significant difference in full-scale intelligence quotient (IQ) postoperatively, but without Bonferroni correction a significant decline by 13.55% (p < 0.05) was observed in the Digit Symbol-Substitution subtest of WAIS-RC. The memory quotient (MQ) of CMS demonstrated a significant decline of 10.65% (p < 0.05) postoperatively. Concerning the participants’ personality characteristics, a significant postoperative increase (p < 0.05) was detected in the Psychoticism (P) trait of EPQ. The mental healthy severity indexes of SCL-90 were decreased postoperatively. After Bonferroni correction, however, there was no statistical difference between pre- and postoperative results on all assessments. Conclusions: Although the patients’ intelligence measures were not changed significantly, their short-term memory and attention appeared to decline postoperatively. In addition, there was a trend towards change in some personality characteristics postoperatively. The postoperative mental health levels of the patients increased, indicating a trend towards improvement. Stereotactic ablation of the NAc in opiate addicts may be associated with short-term negative psychological functions. Advisement regarding the safety of the new surgical modality and recommendations for further investigation are necessary.
Estimate of Dementia Prevalence in a Community Sample from São Paulo, Brazil
Authors: Bottino Cássio M.C. , Azevedo, Jr. Dionisio , Tatsch Mariana , Hototian Sergio R. , Moscoso Marco A. , Folquitto Jefferson , Scalco Andreia Z. , Bazzarella Mario C. , Lopes Marcos A. , Litvoc Julio
Published: October 2008

Aims: To estimate dementia prevalence and describe the etiology of dementia in a community sample from the city of São Paulo, Brazil. Methods: A sample of subjects older than 60 years was screened for dementia in the first phase. During the second phase, the diagnostic workup included a structured interview, physical and neurological examination, laboratory exams, a brain scan, and DSM-IV criteria diagnosis. Results: Mean age was 71.5 years (n = 1,563) and 58.3% had up to 4 years of schooling (68.7% female). Dementia was diagnosed in 107 subjects with an observed prevalence of 6.8%. The estimate of dementia prevalence was 12.9%, considering design effect, nonresponse during the community phase, and positive and negative predictive values. Alzheimer’s disease was the most frequent cause of dementia (59.8%), followed by vascular dementia (15.9%). Older age and illiteracy were significantly associated with dementia. Conclusions: The estimate of dementia prevalence was higher than previously reported in Brazil, with Alzheimer’s disease and vascular dementia being the most frequent causes of dementia. Dementia prevalence in Brazil and in other Latin American countries should be addressed by additional studies to confirm these higher dementia rates which might have a sizable impact on countries’ health services.
Apolipoprotein E Polymorphism and Brain Morphology in Mild Cognitive Impairment
Authors: Thomann Philipp A. , Roth Ann-Sophie , Dos Santos Vasco , Toro Pablo , Essig Marco , Schröder Johannes
Published: October 2008

Background: The apolipoprotein E (ApoE) genotype has been confirmed as the major genetic risk factor for late-onset Alzheimer’s disease (AD). How the ApoE genotype and brain morphology relate to each other is only partly understood, particularly in mild cognitive impairment, the assumed prestage of AD. Methods: A total of 83 subjects with mild cognitive impairment (aging-associated cognitive decline criteria) were investigated with optimized voxel-based morphometry (VBM). We tested for differences in gray and white matter densities between groups according to their ApoE status, i.e. Ε4 allele noncarriers (n = 42), subjects with one Ε4 allele (n = 27) and subjects with two Ε4 alleles (n = 14). Results: In individuals carrying two Ε4 alleles, VBM revealed a decline in gray matter density predominantly in the medial temporal lobe region. Subjects with a single copy of the Ε4 allele exhibited gray matter atrophy in the right inferior frontal gyrus. With respect to white matter changes, atrophy was only found in subjects homozygous for Ε4 and confined to the right superior and middle temporal gyrus. Conclusion: Our findings support the hypothesis that the ApoE genotype in mild cognitive impairment might be associated with structural changes typically found in the early stages of AD.
Hippocampal Surface Analysis in Subjective Memory Impairment, Mild Cognitive Impairment and Alzheimer’s Dementia
Authors: Tepest Ralf , Wang Lei , Csernansky John G. , Neubert Philip , Heun Reinhard , Scheef Lukas , Jessen Frank
Published: October 2008

Background/Aims: Alzheimer’s disease (AD) is preceded by prodromal states. To determine the neuroanatomical basis for the relationship among such states, we assessed surface conformations of the hippocampus in AD, mild cognitive impairment (MCI) and subjective memory impairment (SMI). Methods: Hippocampal surfaces were reconstructed three-dimensionally via large-deformation high-dimensional MRI brain mapping in 14 SMI, 15 MCI, 12 AD and 13 controls. The surfaces were divided a priori into lateral, superior and inferior-medial zones, which approximated the CA1, combined CA2, CA3, CA4 subfields and the subiculum, respectively. Results: Group differences reached statistical significance in the lateral zone (F = 3.2, d.f. = 3, p = 0.033) and inferior-medial zone (F = 2.8, d.f. = 3, p = 0.049) subfields. The groups differed in total hippocampal volume only at the trend level (F = 2.5, d.f. = 3, p = 0.071). Surface deformation maps revealed similar patterns in SMI, MCI and AD subjects, but quantitative differences were significant only when comparing MCI and AD with control subjects. Conclusions: Hippocampal surface deformation in the CA1 subfield was most pronounced in AD, less so in MCI and minor in SMI subjects. These results suggest that hippocampus degeneration develops gradually in AD, and may be observable long before dementia is apparent.
Inhibition of ATP-Induced Glutamate Release by MRS2179 in Cultured Dorsal Spinal Cord Astrocytes
Authors: Zeng Jun-Wei , Liu Xiao-Hong , He Wen-juan , Du Lu , Zhang Jin-Hai , Wu Xi-Gui , Ruan Huai-Zhen
Published: October 2008

It was reported that ATP, an excitatory chemical mediator, exerts its effects by activation of the P2X (ligand-gated cationic channels) and P2Y (G protein-coupled receptors) purinoceptors in the nervous system. In the present work, we used confocal laser scanning microscopy and high-performance liquid chromatography to assess the role of the P2Y1 receptor in ATP-evoked Ca2+ mobilization and glutamate release from cultured dorsal spinal cord astrocytes. ATP (0.01–100 µmol/l) produces a dose-dependent rise in the Ca2+ relative fluorescence intensity in cultured astrocytes. N6methyl-2′-deoxyadenosine-3′,5′-bisphosphate (MRS2179, 0.01–100 µmol/l), a P2Y1-specific antagonist, could dose-dependently inhibit ATP-evoked Ca2+ mobilization. In addition, 100 µmol/l ATP caused glutamate efflux from cultured dorsal spinal cord astrocytes in a time-dependent manner. 100 µmol/l MRS2179 significantly inhibited the glutamate efflux induced by ATP, which suggests that P2Y1 receptor activation is responsible for the ATP-induced glutamate efflux from astrocytes. Taken together, our results demonstrate that P2Y1 receptor plays an important role in modulating the function of astrocytes, which raises the possibility that MRS2179, a potent P2Y1-specific antagonist, may become a potential drug in treating many chronic neurological diseases characterized by astrocytic activation in the nervous system.
Follow-Up Interviews after Eclampsia
Authors: Andersgaard Alice Beathe , Herbst Andreas , Johansen Marianne , Borgström Anna , Bille Anna Gry , Øian Pål
Published: October 2008

Background/Aims: The aim of the study was to assess the prevalence of persisting symptoms 6 months or more after eclampsia. Methods: During a 2-year period (mid-1998 to mid-2000), 210 patients with eclampsia were included in a prospective cohort study of eclampsia in Denmark, Norway and Sweden. One hundred and twenty-three women (59%) were followed up with a structured telephone interview, 6–24 months (median 11) after their eclamptic fit. Results: At the time of follow-up, 63 women (51%) had at least one persistent symptom; 2 patients had severe neurological sequels (hemiparesis and dysarthria), 11% had visual disturbances, 22% had problems concentrating or recalling phone numbers and messages, 18% reported frequent headaches and 10% had vertigo or balance problems. Conclusion: Although few women suffered from severe sequels, many women had persisting symptoms following eclampsia indicating a need for follow-up of these patients. A case-control study comparing the health and symptoms between women having suffered from eclampsia and women without this complication may therefore be justified.