bluuebunny/crossref_metadata_2025 huggingface dataset:
Nature and evolution of the Slave Province subcontinental lithospheric mantleThis article is one of a series of papers published in this Special Issue on the theme Lithoprobe — parameters, processes, and the evolution of a continent.
Authors: Heaman Larry M. , Pearson D. Graham
Published: May 2010

A review of the ages determined for mantle material (xenoliths and xenocrysts entrained in kimberlite) derived from the Slave Province continental lithospheric mantle (CLM) indicates that a portion of the central Slave lithosphere may be ancient (3.5–3.3 Ga) harzburgite, but the majority of this lithosphere is much younger (2.9–2.0 Ga). Relying on the most robust chronometers, the majority of Slave lithosphere peridotite formed in the Neoarchean (peak at 2.75 Ga), whereas the majority of eclogite formed in the Paleoproterozoic (2.2–2.0 Ga). The northern Slave lithosphere contains evidence of peridotite xenolith ages that young with depth. The Paleoproterozoic eclogites may have multiple origins including remnants of subducted oceanic crust and mafic–ultramafic magmas that crystallized at great depth (100–200 km). Re–Os studies of sulfide inclusions in diamond indicate that some diamonds currently mined are ancient (∼3.5 Ga), but many Slave diamonds could be considerably younger. Most eclogitic diamonds recovered from the Slave craton are interpreted to be related to the formation of Paleoproterozoic eclogite. There is abundant evidence for Mesoproterozoic modification of the Slave lithosphere (e.g., heating by magma emplacement at great depth and metasomatism) and possible new addition to the lithosphere at that time. The Canadian Slave and African Kaapvaal lithospheres have similar peaks in cratonic peridotite formation ages at about 2.8 Ga, indicating that a large portion of the CLM in these two cratons formed and stabilized in the Neoarchean. One difference is that the Slave peridotites are much less enriched in SiO2, possibly reflecting the more metasomatized nature of the Kaapvaal CLM. The dominance of Paleoproterozoic formation ages for Slave mantle eclogites contrasts with the dominance of Neoarchean formation ages for Kaapvaal mantle eclogites.
Thermal regime of the lithosphere in the Canadian ShieldThis article is one of a series of papers published in this Special Issue on the themeLithoprobe — parameters, processes, and the evolution of a continent.
Authors: Perry Claire , Rosieanu Carmen , Mareschal Jean-Claude , Jaupart Claude
Published: May 2010

Geothermal studies were conducted within the framework of Lithoprobe to systematically document variations of heat flow and surface heat production in the major geological provinces of the Canadian Shield. One of the main conclusions is that in the Shield the variations in surface heat flow are dominated by the crustal heat generation. Horizontal variations in mantle heat flow are too small to be resolved by heat flow measurements. Different methods constrain the mantle heat flow to be in the range of 12–18 mW·m–2. Most of the heat flow anomalies (high and low) are due to variations in crustal composition and structure. The vertical distribution of radioelements is characterized by a differentiation index (DI) that measures the ratio of the surface to the average crustal heat generation in a province. Determination of mantle temperatures requires the knowledge of both the surface heat flow and DI. Mantle temperatures increase with an increase in surface heat flow but decrease with an increase in DI. Stabilization of the crust is achieved by crustal differentiation that results in decreasing temperatures in the lower crust. Present mantle temperatures inferred from xenolith studies and variations in mantle seismic P-wave velocity (Pn) from seismic refraction surveys are consistent with geotherms calculated from heat flow. These results emphasize that deep lithospheric temperatures do not always increase with an increase in the surface heat flow. The dense data coverage that has been achieved in the Canadian Shield allows some discrimination between temperature and composition effects on seismic velocities in the lithospheric mantle.
Initiation, development, and benefits of Lithoprobe — shaping the direction of Earth science research in Canada and beyondThis article is one of a series of papers published in this Special Issue on the theme Lithoprobe — parameters, processes, and the evolution of a continent.Lithoprobe Contribution 1480.
Authors: Clowes Ron M.
Published: May 2010

Lithoprobe is Canada’s national, collaborative, multidisciplinary, Earth science research project established to develop a comprehensive understanding of the evolution of northern North America. It is regarded internationally as one of the most successful national geoscience projects ever undertaken. Part of Lithoprobe’s success derives from its history and organizational structure. A one-year Phase I program (1984–1985) was highly successful. Phases II to V carried the project forward until 2005, when funding terminated. Lithoprobe was organized as a decentralized research network of multidisciplinary scientific studies and collaborating scientists. About 1500 scientific publications were generated. Lithoprobe’s legacy also includes economic and social benefits. New and improved understanding of Earth history provides petroleum and mining companies with an enhanced knowledge base. Lithoprobe demonstrated the applicability of high-resolution seismic reflection studies to mineral exploration. Development of a portable seismic refraction recorder and a long-period magnetotelluric system led to technology transfer to Canadian companies. Very high-resolution seismic reflection studies, applied first by Lithoprobe, are proving effective for exploration for uranium deposits in Saskatchewan. In the cratonic areas of Canada, Lithoprobe seismic and magnetotelluric studies have provided significant new information relevant to exploration for diamonds. On the west coast of Canada, Lithoprobe studies provided data and a framework for better understanding the mega-thrust earthquake hazard in the region. Lithoprobe established a highly effective public outreach strategy that involved the print and electronic media as well as material for educational purposes. Unequivocally, Lithoprobe has enhanced the already strong reputation of the Earth sciences in Canada.
Mantle heterogeneities and their significance: results from Lithoprobe seismic reflection and refraction – wide-angle reflection studiesThis article is one of a series of papers published in this Special Issue on the themeLithoprobe — parameters, processes, and the evolution of a continent.Lithoprobe Contribution 1486.
Authors: Clowes Ron M. , White Don J. , Hajnal Zoltan
Published: May 2010

Within Lithoprobe’s 10 transects, data from more than 20 000 km of multichannel seismic (MCS) reflection profiling and 12 refraction – wide-angle reflection (R/WAR) surveys were acquired. While the main results related to crustal structure, the data also indicated substantial heterogeneity in the lithospheric mantle. Images of fossilized subduction zones from the Eocene to the Neoarchean demonstrate that current plate tectonic processes have been active for more than 2.6 Ga. The Canadian Cordillera has a thin (50–60 km) lithosphere that is likely receiving some dynamic support from the asthenosphere below. Vestiges of the last stage of accretionary tectonic processes that formed the Archean Superior craton are indicated by an unusual anisotropic high velocity layer that may represent relic oceanic lithosphere. Within the Paleoproterozoic Trans-Hudson Orogen, a restricted region of upper mantle P-wave velocity anisotropy is identified with the continental collision between the bounding Hearne and Superior cratons. In the Archean Hearne and Wyoming provinces, two dipping structures within the sub-crustal lithosphere are interpreted as subduction features related to the assembly of the two cratons. Finite-difference modeling of long-offset data (over 1300 km) reveals fine-scale heterogeneities within a layer between 90 and 150 km in the continental lithosphere, perhaps formed through lateral flow or deformation within the upper mantle. Based on Lithoprobe data, heterogeneities within the lithospheric mantle are reasonably common. They have a wide range of seismic signatures, include many different types and show differing scales. Nevertheless, their extent in the lithospheric mantle is considerably less than in the crust.
Upper mantle thermochemical structure from seismic–geodynamic flow models: constraints from the Lithoprobe initiativeThis article is one of a series of papers published in this Special Issue on the theme Lithoprobe — parameters, processes, and the evolution of a continent.
Authors: Perry H. K. Claire , Forte Alessandro
Published: May 2010

High-resolution seismic models of three-dimensional mantle heterogeneity are interpreted in terms of upper mantle thermal and compositional anomalies. These anomalies produce density perturbations that drive mantle flow and corresponding convection-related geophysical observables, such as the nonhydrostatic geoid, free-air gravity anomalies, and dynamic surface topography, and provide constraints on internal mantle density structure. The convection related observables are corrected for the isostatically compensated crustal heterogeneity and compared with those predicted by tomography-based mantle flow models. Occam inversions of the surface topography and gravity data provide inferences of the velocity–density scaling coefficients, which characterize mantle density anomalies below North America. The inferred density anomalies require simultaneous contributions from temperature and composition. The density and seismic shear velocity anomalies place constraints on the thermochemical structure of the mantle beneath the North American craton. Perturbations in the molar ratio of iron, R = XFe/(XFe + XMg), are used to quantify the compositional anomalies in terms of iron depletion in the sub-continental mantle. Estimates of the extent of basalt depletion in the tectosphere beneath North America are obtained. This depletion is interpreted to produce a local balance between positive chemical buoyancy and the negative thermal buoyancy that would otherwise be produced by the colder temperatures of the sub-cratonic mantle relative to its sub-oceanic counterpart.
SYNTHESES, MAGNETIC AND TRANSPORT PROPERTIES OF NbSr2(RE1.5Ce0.5)Cu2O10; RE = Tb, Ho, Er SERIES
Authors: BALAMURUGAN S.
Published: May 2010

The structural, magnetic and transport/electric properties of 1222-type niobio-cuprates, NbSr 2( RE 1.5 Ce 0.5) Cu 2 O 10; RE = Tb , Ho , Er compounds prepared by high pressure and high temperature synthesis conditions have been investigated and discussed briefly. In order to obtain good samples, several samples have been prepared under wide synthesis conditions between 1250°C and 1550°C for 1–2 hours at a constant high pressure of 6 GPa. The samples synthesized under extreme conditions show that they have tetragonal crystal structure with I4/mmm as a possible space group. Neither superconductivity nor magnetic ordering are seen for RE = Tb in magnetic susceptibility measurements. On the other hand, the RE = Ho compound shows magnetic transition at around 30 K. This is due to the mixed magnetic state that arises from the main 1222 phase. The RE = Er compound reveals a ferromagnetic-like transition at ~ 26 K. Unlike RE = Y , the magnetic properties of RE = Dy , Tb , Ho , Er compounds are found to be insensitive to the synthesis conditions. None of the samples showed zero resistance (bulk superconductivity) transitions and all samples reveal semiconducting characteristics. The sample with RE = Ho shows relatively low resistivity compared to the other two samples ( RE = Tb , Er ). All the samples show temperature and field dependence of magnetoresistance about 1–6%. The nearly linear dependence suggests that hopping conduction is dominant in a certain temperature range for all the three studied compounds.
EXPONENTIAL STABILITY FOR STOCHASTIC NEURAL NETWORKS OF NEUTRAL TYPE WITH IMPULSIVE EFFECTS
Authors: SAKTHIVEL RATHINASAMY , SAMIDURAI R. , ANTHONI S. MARSHAL
Published: May 2010

This paper is concerned with the exponential stability of stochastic neural networks of neutral type with impulsive effects. By employing the Lyapunov functional and stochastic analysis, a new stability criterion for the stochastic neural network is derived in terms of linear matrix inequality. A numerical example is provided to show the effectiveness and applicability of the obtained result.
SPECTROSCOPIC AND THERMAL STUDIES OF GEL-GROWN COPPER MALONATE CRYSTALS
Authors: MATHEW VARGHESE , JOSEPH JOCHAN , JACOB SABU , XAVIER LIZYMOL , ABRAHAM K. E.
Published: May 2010

Copper malonate crystals were grown using silica gel as the growth medium. The grown crystals were characterized by X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR) and Fourier transform Raman spectroscopy (FT Raman). The thermal decomposition of the compound was investigated using thermogravimetry (TG) and derivative thermogravimetry (DTG) measurements.
MODELING MULTILAYER ANTIREFLECTION COATING SYSTEMS BASED ONLiNbO3
Authors: KARAOMERLIOGLU FILIZ
Published: May 2010

Antireflection coatings have had the greatest impact on optics. The antireflection (AR) coating is the critically important technology in obtaining high performance of optoelectronic devices. In the present paper, characteristics of the ferroelectric based multilayered antireflection coating systems are investigated. Multilayer antireflection coatings consisting of insulator thin films have been modeled in the region between the 400 nm and 800 nm visible bands of electromagnetic spectrum to reduce reflectance from ferroelectric based substrate.

In this type of antireflection coating we can regulate the optical properties of a system by external electric (or thermal field) and design a broadband low reflection coating system for optoelectronic devices. In order to design and simulate the normal incidence wideband visible multilayer AR coatings, we have developed a Fortran software program based upon Fresnell equations. Different types of layers which are two-different materials like ZnSe and ZrO2for even-folded multilayer (two-, four-, six-, eight-, ten-, and twelve-layer) antireflection coatings are used. Ferroelectric material, LiNbO3is used as the substrate. The optical thicknesses of each layer are equal to a quarter-wave thick at a certain wavelength.
STABLE PAIRS
Authors: HENCKELL K.
Published: May 2010

For a finite semigroup S and pseudovariety V, (Y, T) is a V-stable pair of S iff Y ⊆ S, T ≤ S and for any relational morphism R : S ⇝ V with V ∈ V there exists a v ∈ V such that Y ⊆ R-1(v) and T ≤ R-1( Stab (v)). X ≤ S is stable if it is generated by an [Formula: see text]-chain {ai} with aiaj = ai for j < i. Given a relation R : S ⇝ A ∈ A (where A denotes the pseudovariety of aperiodic semigroups) that computes PlA(S), we construct a new relation R∞ : S ⇝ (A(M))# that computes A-stable pairs. This proves the main result of this paper: (Y, T) is an A-stable pair of S iff T ≤ ∪ X for some stableX ≤ PlA(S) and Y ⊆ Y' for some Y' ∈ PlA(S) with Y'x = Y' for all x ∈ X. As a corollary we get that if V is a local pseudovariety of semigroups, then V * A has decidable membership problem.
A PROFINITE APPROACH TO STABLE PAIRS
Authors: HENCKELL KARSTEN , RHODES JOHN , STEINBERG BENJAMIN
Published: May 2010

We give a short proof, using profinite techniques, that idempotent pointlikes, stable pairs and triples are decidable for the pseudovariety of aperiodic monoids. Stable pairs are also described for the pseudovariety of all finite monoids.
APERIODIC POINTLIKES AND BEYOND
Authors: HENCKELL KARSTEN , RHODES JOHN , STEINBERG BENJAMIN
Published: May 2010

We prove that if π is a recursive set of primes, then pointlike sets are decidable for the pseudovariety of semigroups whose subgroups are π-groups. In particular, when π is the empty set, we obtain Henckell's decidability of aperiodic pointlikes. Our proof, restricted to the case of aperiodic semigroups, is simpler than the original proof.
A STRUCTURAL APPROACH TO THE LOCALITY OF PSEUDOVARIETIES OF THE FORM LH ⓜ V
Authors: STEINBERG B.
Published: May 2010

We show that if H is a Fitting pseudovariety of groups and V is a local pseudovariety of monoids, then LH ⓜ V is local if either V contains the six element Brandt monoid, or H is a non-trivial pseudovariety of groups closed under extension.
WEAKLY ITERATED BLOCK PRODUCTS AND APPLICATIONS TO LOGIC AND COMPLEXITY
Authors: STRAUBING HOWARD , TESSON PASCAL , THÉRIEN DENIS
Published: May 2010

Unlike the wreath product, the block product is not associative at the level of varieties. All decomposition theorems involving block products, such as the bilateral version of Krohn–Rhodes' theorem, have always assumed a right-to-left bracketing of the operands. We consider here the left-to-right bracketing, which is generally weaker.

More precisely, we are interested in characterizing for any pseudovarieties of monoids U, V the smallest pseudovariety W that contains U and such that W □ V = W. This allows us to obtain new decomposition results for a number of important varieties such as DA, DO and DA * G.

We apply these results to characterize the regular languages definable with generalized first-order sentences using only two variables and to shed new light on recent results on regular languages recognized by bounded-depth circuits with a linear number of wires and regular languages with small communication complexity.
ANIMAL MICRORNA TARGET PREDICTION USING DIVERSE SEQUENCE-SPECIFIC DETERMINANTS
Authors: ZHENG YUN , ZHANG WEIXIONG
Published: May 2010

Many recent studies have shown that access of animal microRNAs (miRNAs) to their complementary sites in target mRNAs is determined by several sequence-specific determinants beyond the seed regions in the 5′ end of miRNAs. These factors have been related to the repressive power of miRNAs and used in some programs to predict the efficacy of miRNA complementary sites. However, these factors have not been systematically examined regarding their capacities for improving miRNA target prediction. We develop a new miRNA target prediction algorithm, called Hitsensor, by incorporating many sequence-specific features that determine complementarities between miRNAs and their targets, in addition to the canonical seed regions in the 5′ ends of miRNAs. We evaluate the performance of our algorithm on 720 known animal miRNA:target pairs in four species, Homo sapiens, Mus musculus, Drosophila melanogaster and Caenorhabditis elegans. Our experimental results show that Hitsensor outperforms five popular existing algorithms, indicating that our unique scheme for quantifying the determinants of complementary sites is effective in improving the performance of a miRNA target prediction algorithm. We also examine the effectiveness of miRNA-mediated repression for the predicted targets by using a published quantitative protein expression dataset of miR-223 knockout in mouse neutrophils. Hitsensor identifies more targets than the existing algorithms, and the predicted targets of Hitsensor show comparable protein level changes to those of the existing algorithms.
Effect of disodiumN,N-dialanyl protoporphyrinate, diarginine protoporphyrinate and diarginineN,N-dialanyl protoporphyrinate on respiratory burst of human neutrophilsin vitro
Authors: Bugaj Andrzej M. , Billert Hanna , Kołodziejska Patrycja , Limaszewska Alina , Stochmal Zuzanna
Published: May 2010

The effect of three amino acid protoporphyrin IX (PPIX) derivatives evaluated as sensitizers in photodynamic therapy — disodium N,N -dialanyl protoporphyrinate ( PP(Ala)2Na2), diarginine protoporphyrinate (PPArg2) and diarginine N,N -dialanyl protoporphyrinate (PP(Ala)2Arg2) – non-irradiated and pre-irradiated with UV-A, on respiratory burst of non-stimulated and opsonized zymosan stimulated neutrophils was studied. A potential synergistic effect of diazepam (7-chloro-1-methyl-5-phenyl-1,3-dihydro-2H-1,4-benzodiazepin-2-one) was also examined. PP(Ala)2Na2showed strong pro-oxidant effect towards non-stimulated neutrophils, while PPArg2and PP(Ala)2Arg2revealed no significant effect. In the case of stimulated neutrophils all studied porphyrins showed antioxidant effect, although for PP(Ala)2Na2this effect was significantly weaker than that of PPArg2and PP(Ala)2Arg2. After pre-irradiation with UV-A (λ = 365 nm, fluence 2.0 J.cm-2, fluence rate 6.7 mW.cm-2) the antioxidant activity of all studied sensitizers towards non-stimulated granulocytes did not change significantly when compared to effects of non-irradiated porphyrins, while in the case of stimulated cells, only PPArg2caused significant decrease of respiratory burst. Non-irradiated diazepam showed significant antioxidant effect and enhanced antioxidant effect of all studied porphyrins towards stimulated neutrophils, while after UV-A pre-irradiation it revealed no significant antioxidant effect on non-stimulated and stimulated neutrophils, both alone and in combination with porphyrin sensitizers.
Phosphorus-nitrogen compounds Part 17: The synthesis, spectral and electrochemical investigations of porphyrino-phosphazenes
Authors: Egemen Gamze , Hayvalı Mustafa , Kılıç Zeynel , Solak A. Osman , Üstündağ Zafer
Published: May 2010

The reactions of unsymmetrical porphyrins (1 and 2) with Ni(OAc)2·4H2O in boiling DMF produce porphyrin complexes (3 and 4). From the reactions of free porphyrin ligands 1 and 2 with hexachlorocyclotriphosphazatriene, N3P3Cl6 , the new free porphyrino-phosphazene derivatives (5 and 6) are obtained. On the other hand, the reactions of N3P3Cl6 with porphyrin complexes (3 and 4) afford the new porphyrino-phosphazene complexes (7 and 8). In the literature there are a few examples of the porphyrino-phosphazene architectures. The structural investigations of all the compounds have been made by elemental analyses, MS, FTIR, 1H NMR, 31P NMR and UV-visible techniques. The cyclic voltammograms (CVs) are examined in acetonitrile (MeCN) containing 0.1 M tetrabutylammonium-tetrafluoroborate (TBATFB) to investigate the surface attachment properties at the glassy carbon electrode (GCE) and the influence of the presence of metal cations in the porphyrin ring.
Interaction between novel porphyrin-dextran nanoparticles and human serum albumin
Authors: Zhang Zhi , Guo Qian-ni , Lu Yun-guo , Jia Tao , Yan Kun , Li Zao-ying
Published: May 2010

A novel porphyrin-dextran coated Fe3O4nanoparticle (5) was designed and synthesized. The structure of 5 was confirmed by IR, UV-vis and inductively coupled plasma atomic emission spectrometry, and dynamic laser scattering (DLS); magnetic property was measured by a vibrating sample magnetometer (VSM). The interaction between compound 5 and human serum albumin (HSA) was investigated through UV-vis absorbance spectra and fluorospectrophotometer, compared with the 5-(4-aminophenyl)-10,15,20-tris-(4-sulfonatophenyl)porphyrin, trisodium salt (3). The results showed compound 5 containing porphyrin moiety and 3 could interact with HSA. The quenching constant (Ksv) was 4.739 × 105M-1for 3, and 2.846 × 105M-1for 5; the apparent affinity binding constant (KA) was 8.562 × 103M-1for 3, and 4.978 × 104M-1for 5.
Ligand changes in ferric species of the giant extracellular hemoglobin ofGlossoscolex paulistusas function of pH: correlations between redox, spectroscopic and oligomeric properties and general implications with different hemoproteins
Authors: Moreira Leonardo Marmo , Poli Alessandra Lima , Lyon Juliana Pereira , Aimbire Flávio , Toledo José Carlos , Costa-Filho Antonio José , Imasato Hidetake
Published: May 2010

The present review is focused on the relationship between oligomeric and heme properties of HbGp, emphasizing the characteristics that can be generalized to other hemoproteins. This study represents the state-of-the-art with respect to the approaches for investigating giant extracellular hemoglobins as well as the correlation between oligomeric assembly alterations and their consequent changes in the first coordination sphere. A wide introduction focused on the properties of this hemoglobin is developed. Indeed, this hemoprotein is considered an interesting prototype of blood substitute and biosensor due to its peculiar properties, such as resistance to autoxidation and oligomeric stability. Previous studies by our group employing UV-vis, EPR and CD spectroscopies have been revised in a complete approach, in agreement with recent and relevant data from the literature. In fact, a consistent and inter-related spectroscopic study is described propitiating a wide assignment of "fingerprint" peaks found in the techniques evaluated in this paper. This review furnishes physicochemical information regarding the identification of ferric heme species of hemoproteins and metallic complexes through their spectroscopic bands. This effort at the attribution of UV-vis, EPR and CD peaks is not restricted to HbGp, and includes a comparative analysis of several hemoproteins involving relevant implications regarding several types of iron-porphyrin systems.
Representation and Accountability in Cities
Authors: Trounstine Jessica
Published: May 2010

Local governments in the United States provide essential services and allocate an enormous share of the country's public goods. Knowing how benefits are distributed and who wins and who loses in American politics requires understanding the functioning of local representative democracy. Pitkin (1967) delineates three components to democratic representation—authorization, responsiveness, and accountability. Elections play a fundamental role in each of these processes, from selecting government officials, to influencing the policies governments choose, to holding representatives accountable for outcomes. Scholars of local politics have tended toward two themes in analyzing the link between elections and representation: exploring the role of race and ethnicity, and understanding how institutions shape both practices and outcomes. Racial and ethnic divisions are prominent in local politics and shape both voting decisions and policy outcomes. Institutions implemented by municipal reformers tend to decrease the visibility of politics and in some situations advantage white, middle/upper-class residents. This review presents the research on both themes, discussing each of Pitkin's components of representation in turn, with the goal of summarizing what we know and what we still need to learn.
Immigration and Social Policy in the United States
Authors: Hero Rodney E.
Published: May 2010

The United States experienced a period of sustained large-scale immigration from the 1960s into the period of dramatic economic recession in 2008–2009. This article focuses on the impact of immigrants and immigration on social policy in the United States. I summarize the arguably, and surprisingly, scant research that specifically examines the political and policy (more than the social and/or economic) implications of immgration. I first look at the extent and nature of change within and across three minority groups over the past several decades, including evidence on their composition and geographic concentration or dispersion. Next considered are the implications of the American “racial order” as a context and its impacts on “racialization” of immigrants. Next examined are the consequences for immigrants in major arenas of American government—urban, state, and national. Although emphasis is given to issues of immigration, the importance of race/ethnicity as a social force in American politics is also considered, of necessity, because immigration and race/ethnicity are strongly interconnected though analytically separable.
Parliamentary Control of Coalition Governments
Authors: Strøm Kaare , Müller Wolfgang C. , Smith Daniel Markham
Published: May 2010

Parliamentary democracy means that the political executive is accountable to the parliamentary majority. However, when both the parliamentary majority and the cabinet consist of two or more distinct political parties, it is often difficult for the parliamentary majority to monitor and control the executive. In this article, we focus on political delegation from parliamentarians to the executive branch under multiparty parliamentary government. We identify the most important mechanisms parliamentary parties employ to remedy the accountability problems that may arise, as well as the arenas in which they are exercised: the executive arena, the parliamentary arena, and the extraparliamentary arena. We discuss the effectiveness of accountability mechanisms arena by arena, examine their use in 15 Western European countries that frequently feature coalition governments, and review our knowledge of how parliaments and parliamentary parties control political delegation and accountability in coalition governments.
The Geographic Distribution of Political Preferences
Authors: Rodden Jonathan
Published: May 2010

In order to address classic questions about democratic representation in countries with winner-take-all electoral districts, it is necessary to understand the distribution of political preferences across districts. Recent formal theory literature has contributed new insights into how parties choose platforms in countries with a continuum of heterogeneous districts. Meanwhile, increases in survey sample sizes and advances in empirical techniques have made it possible to characterize the distribution of preferences within and across electoral districts. This review addresses an emerging literature that builds on these new tools to explore the ways in which the geography of political preferences can help explain the parties that compete, the platforms and policies they choose, and even the rules under which they compete. Building on insights from economic and political geography, it pays special attention to electoral and policy biases that can emerge when there is an asymmetric distribution of preferences across districts.
Interaction of PGHS-2 and glutamatergic mechanisms controlling the ovine fetal hypothalamus-pituitary-adrenal axis
Authors: Knutson Nathan , Wood Charles E.
Published: May 2010

Prostaglandins, generated within the fetal brain, are integral components of the mechanism controlling the fetal hypothalamus-pituitary-adrenal (HPA) axis. Previous studies in this laboratory demonstrated that prostaglandin G/H synthase isozyme 2 (PGHS-2) inhibition reduces the fetal HPA axis response to cerebral hypoperfusion, blocks the preparturient rise in fetal plasma ACTH concentration, and delays parturition. We also discovered that blockade of N-methyl-d-aspartate (NMDA) receptors reduces the fetal ACTH response to cerebral hypoperfusion. The present study was designed to test the hypothesis that PGHS-2 action and the downstream effect of HPA axis stimulation are stimulated by NMDA-mediated glutamatergic neurotransmission. Chronically catheterized late-gestation fetal sheep ( n = 8) were injected with NMDA (1 mg iv). All responded with increases in fetal plasma ACTH and cortisol concentrations. Pretreatment with resveratrol (100 mg iv, n = 5), a specific inhibitor of PGHS-1, did not alter the magnitude of the HPA axis response to NMDA. Pretreatment with nimesulide (10 mg iv, n = 6), a specific inhibitor of PGHS-2, significantly reduced the HPA axis response to NMDA. To further explore this interaction, we injected NMDA in six chronically catheterized fetal sheep that were chronically infused with nimesulide ( n = 6) at a rate of 1 mg/day into the lateral cerebral ventricle for 5–7 days. In this group, there was no significant ACTH response to NMDA. Finally, we tested whether the HPA axis response to prostaglandin E2 (PGE2) is mediated by NMDA receptors. Seven chronically catheterized late-gestation fetal sheep were injected with 100 ng of PGE2, which significantly increased fetal plasma ACTH and cortisol concentrations. Pretreatment with ketamine (10 mg iv), an NMDA antagonist, did not alter the ACTH or cortisol response to PGE2. We conclude that generation of prostanoids via the action of PGHS-2 in the fetal brain augments the fetal HPA axis response to NMDA-mediated glutamatergic stimulation.
Cholinergic Modulation of the Resonance Properties of Stellate Cells in Layer II of Medial Entorhinal Cortex
Authors: Heys James G. , Giocomo Lisa M. , Hasselmo Michael E.
Published: May 2010

In vitro whole cell patch-clamp recordings of stellate cells in layer II of medial entorhinal cortex show a subthreshold membrane potential resonance in response to a sinusoidal current injection of varying frequency. Physiological recordings from awake behaving animals show that neurons in layer II medial entorhinal cortex, termed “grid cells,” fire in a spatially selective manner such that each cell's multiple firing fields form a hexagonal grid. Both the spatial periodicity of the grid fields and the resonance frequency change systematically in neurons along the dorsal to ventral axis of medial entorhinal cortex. Previous work has also shown that grid field spacing and acetylcholine levels change as a function of the novelty to a particular environment. Using in vitro whole cell patch-clamp recordings, our study shows that both resonance frequency and resonance strength vary as a function of cholinergic modulation. Furthermore, our data suggest that these changes in resonance properties are mediated through modulation of h-current and m-current.
Forward Sensitivity Approach to Dynamic Data Assimilation
Authors: Lakshmivarahan S. , Lewis J. M.
Published: May 2010

The least squares fit of observations with known error covariance to a strong‐constraint dynamical model has been developed through use of the time evolution of sensitivity functions—the derivatives of model output with respect to the elements of control (initial conditions, boundary conditions, and physical/empirical parameters). Model error is assumed to stem from incorrect specification of the control elements. The optimal corrections to control are found through solution to an inverse problem. Duality between this method and the standard 4D‐Var assimilation using adjoint equations has been proved. The paper ends with an illustrative example based on a simplified version of turbulent heat transfer at the sea/air interface.
Implications of Parameter Uncertainty on Option Prices
Authors: Lindström Erik
Published: May 2010

Financial markets are complex processes where investors interact
to set prices. We present a framework for option valuation under imperfect
information, taking risk neutral parameter uncertainty into account. The
framework is a direct generalization of the existing valuation methodology.
Many investors base their decisions on mathematical models that have been
calibrated to market prices. We argue that the calibration process introduces
a source of uncertainty that needs to be taken into account. The models
and parameters used may differ to such extent that one investor may find an
option underpriced; whereas another investor may find the very same option
overpriced. This problem is not taken into account by any of the standard
models. The paper is concluded by presenting simulations and an empirical study
on FX options, where we demonstrate improved predictive performance (in sample and out of sample) using this framework.
Variation in Provider Identification of Obesity by Individual- and Neighborhood-Level Characteristics among an Insured Population
Authors: Bleich Sara N. , Clark Jeanne M. , Goodwin Suzanne M. , Huizinga Mary Margaret , Weiner Jonathan P.
Published: May 2010

Objective. The purpose of this study was to examine whether neighborhood- and individual-level characteristics affect providers' likelihood of providing an obesity diagnosis code in their obese patients' claims.Methods. Logistic regressions were performed with obesity diagnosis code serving as the outcome variable and neighborhood characteristics and member characteristics serving as the independent variables (N= 16,151 obese plan members).Results. Only 7.7 percent of obese plan members had an obesity diagnosis code listed in their claims. Members living in neighborhoods with the largest proportions of Blacks were 29 percent less likely to receive an obesity diagnosis (P<.05). The odds of having an obesity diagnosis code were greater among members who were female, aged 44 or below, hypertensive, dyslipidemic, BMI ≥ 35 kg/m2, had a larger number of provider visits, or who lived in an urban area (allP<.05).Conclusions. Most health care providers do not include an obesity diagnosis code in their obese patients' claims. Rates of obesity identification were strongly related to individual characteristics and somewhat associated with neighborhood characteristics.
Prime-Boost Vaccination Using Chemokine-Fused gp120 DNA and HIV Envelope Peptides Activates Both Immediate and Long-Term Memory Cellular Responses in Rhesus Macaques
Authors: Qin Hong , Nehete Pramod N. , He Hong , Nehete Bharti , Buchl Stephanie , Cha Soung-chul , Sastry Jagannadha K. , Kwak Larry W.
Published: May 2010

HIV vaccine candidates with improved immunogenicity and induction of mucosal T-cell immunity are needed. A prime-boost strategy using a novel HIV glycoprotein 120 DNA vaccine was employed to immunize rhesus macaques. The DNA vaccine encoded a chimeric gp120 protein in fusion with monocyte chemoattractant protein-3, which was hypothesized to improve the ability of antigen-presenting cells to capture viral antigen through chemokine receptor-mediated endocytosis. DNA vaccination induced virus-reactive T cells in peripheral blood, detectable by T cell proliferation, INFγELISPOT and sustained IL-6 production, without humoral responses. With a peptide-cocktail vaccine containing a set of conserved polypeptides of HIV-1 envelope protein, given by nasogastric administration, primed T-cell immunity was significantly boosted. Surprisingly, long-term and peptide-specific mucosal memory T-cell immunity was detected in both vaccinated macaques after one year. Therefore, data from this investigation offer proof-of-principle for potential effectiveness of the prime-boost strategy with a chemokine-fused gp120 DNA and warrant further testing in the nonhuman primate models for developing as a potential HIV vaccine candidate in humans.
Inflammatory Molecules in Aqueous Humour and on Ocular Surface and Glaucoma Surgery Outcome
Authors: Cvenkel Barbara , Kopitar Andreja Nataša , Ihan Alojz
Published: May 2010

Purpose. To investigate the influence of inflammatory molecules in the aqueous humour and on the ocular surface on the outcome of glaucoma surgery.Methods. Thirty patients who needed antiglaucomatous surgery were included. The interleukin- (IL-) 8, IL-1, IL-6, IL-10, tumour necrosis factor- (TNF-) ; and IL-12 were determined from aqueous humour preoperatively and the imprints of conjunctiva were analysed for expression of human leukocyte antigen- (HLA-)-DR after surgery by flow cytometry. The success of trabeculectomy was defined as intraocular pressure less than 21 mmHg without antiglaucoma medication.Results. Eyes with trabeculectomy failure at 3 months showed significantly higher TNF- and IL-6 levels in the aqueous than eyes with successful surgery. Increased expression of HLA-DR on epithelial cells and antigen-presenting cells was not associated with the trabeculectomy outcome.Conclusions. Higher preoperative levels of TNF- and IL-6 in aqueous humour may contribute to the development of inflammatory milieu and were associated with worse outcome of glaucoma surgery.
Three-Dimensional Cell Growth Confers Radioresistance by Chromatin Density Modification
Authors: Storch Katja , Eke Iris , Borgmann Kerstin , Krause Mechthild , Richter Christian , Becker Kerstin , Schröck Evelin , Cordes Nils
Published: May 2010

Cell shape and architecture are determined by cell-extracellular matrix interactions and have profound effects on cellular behavior, chromatin condensation, and tumor cell resistance to radiotherapy and chemotherapy. To evaluate the role of chromatin condensation for radiation cell survival, tumor cells grown in three-dimensional (3D) cell cultures as xenografts and monolayer cell cultures were compared. Here, we show that increased levels of heterochromatin in 3D cell cultures characterized by histone H3 deacetylation and induced heterochromatin protein 1α expression result in increased radiation survival and reduced numbers of DNA double strand breaks (DSB) and lethal chromosome aberrations. Intriguingly, euchromatin to heterochromatin–associated DSBs were equally distributed in irradiated 3D cell cultures and xenograft tumors, whereas irradiated monolayer cultures showed a 2:1 euchromatin to heterochromatin DSB distribution. Depletion of histone deacetylase (HDAC) 1/2/4 or application of the class I/II pharmacologic HDAC inhibitor LBH589 induced moderate or strong chromatin decondensation, respectively, which was translated into cell line–dependent radiosensitization and, in case of LBH589, into an increased number of DSBs. Neither growth conditions nor HDAC modifications significantly affected the radiation-induced phosphorylation of the important DNA repair protein ataxia telangiectasia mutated. Our data show an interrelation between cell morphology and cellular radiosensitivity essentially based on chromatin organization. Understanding the molecular mechanisms by which chromatin structure influences the processing of radiation-induced DNA lesions is of high relevance for normal tissue protection and optimization of cancer therapy. Cancer Res; 70(10); 3925–34. ©2010 AACR.
Estrogen-Dependent and Estrogen-Independent Mechanisms Contribute to AIB1-Mediated Tumor Formation
Authors: Torres-Arzayus Maria I. , Zhao Jin , Bronson Roderick , Brown Myles
Published: May 2010

We have previously reported the oncogenic properties of the gene amplified in breast cancer 1 (AIB1), a member of the p160 family of hormone receptor coactivators. In a transgenic mouse model, AIB1 overexpression resulted in a high incidence of tumors in various tissues, including mammary gland, uterus, lung, and pituitary. To determine whether the AIB1 oncogenicity in this model depended on its function as an estrogen receptor (ER) coactivator, we abolished ER signaling through two independent approaches, by performing ovariectomy on AIB1 transgenic (AIB1-tg) mice to prevent gonadal estrogen production and by crossing AIB1-tg mice with ERα-null mutant mice. Ovariectomized (ovx) mice, but not AIB1 × ERα−/− mice, still developed mammary gland hyperplasia and ductal carcinoma in situ. Both approaches, however, completely prevented the development of invasive mammary tumors, indicating that invasive mammary tumor formation is strictly estrogen dependent. Once developed, AIB1-induced mammary tumors can subsequently lose their dependence on estrogen: Injection of ERα(+) tumor cell lines derived from such tumors into ovx or untreated wild-type mice resulted in a similar rate of tumor growth in both groups. Surprisingly, however, ovx mice had an ∼4-fold higher rate of metastasis formation, suggesting that estrogen provided some protection from metastasis formation. Lastly, our experiments identified oncogenic functions of AIB1 that are independent of its ER coactivation, as both approaches, ovariectomy and ER−/− crosses, still resulted in a high incidence of tumors in the lung and pituitary. We therefore conclude that AIB1 can exert its oncogenicity through tissue-specific estrogen-dependent and estrogen-independent functions. Cancer Res; 70(10); 4102–11. ©2010 AACR.
Preclinical Evaluation of an 131I-Labeled Benzamide for Targeted Radiotherapy of Metastatic Melanoma
Authors: Joyal John L. , Barrett John A. , Marquis John C. , Chen Jianqing , Hillier Shawn M. , Maresca Kevin P. , Boyd Marie , Gage Kenneth , Nimmagadda Sridhar , Kronauge James F. , Friebe Matthias , Dinkelborg Ludger , Stubbs James B. , Stabin Michael G. , Mairs Rob , Pomper Martin G. , Babich John W.
Published: May 2010

Radiolabeled benzamides are attractive candidates for targeted radiotherapy of metastatic melanoma as they bind melanin and exhibit high tumor uptake and retention. One such benzamide, N-(2-diethylamino-ethyl)-4-(4-fluoro-benzamido)-5-iodo-2-methoxy-benzamide (MIP-1145), was evaluated for its ability to distinguish melanin-expressing from amelanotic human melanoma cells, and to specifically localize to melanin-containing tumor xenografts. The binding of [131I]MIP-1145 to melanoma cells in vitro was melanin dependent, increased over time, and insensitive to mild acid treatment, indicating that it was retained within cells. Cold carrier MIP-1145 did not reduce the binding, consistent with the high capacity of melanin binding of benzamides. In human melanoma xenografts, [131I]MIP-1145 exhibited diffuse tissue distribution and washout from all tissues except melanin-expressing tumors. Tumor uptake of 8.82% injected dose per gram (ID/g) was seen at 4 hours postinjection and remained at 5.91% ID/g at 24 hours, with tumor/blood ratios of 25.2 and 197, respectively. Single photon emission computed tomography imaging was consistent with tissue distribution results. The administration of [131I]MIP-1145 at 25 MBq or 2.5 GBq/m2 in single or multiple doses significantly reduced SK-MEL-3 tumor growth, with multiple doses resulting in tumor regression and a durable response for over 125 days. To estimate human dosimetry, gamma camera imaging and pharmacokinetic analysis was performed in cynomolgus monkeys. The melanin-specific binding of [131I]MIP-1145 combined with prolonged tumor retention, the ability to significantly inhibit tumor growth, and acceptable projected human dosimetry suggest that it may be effective as a radiotherapeutic pharmaceutical for treating patients with metastatic malignant melanoma. Cancer Res; 70(10); 4045–53. ©2010 AACR.
Microtubule Dynamics, Mitotic Arrest, and Apoptosis: Drug-Induced Differential Effects of βIII-Tubulin
Authors: Gan Pei Pei , McCarroll Joshua A. , Po'uha Sela T. , Kamath Kathy , Jordan Mary Ann , Kavallaris Maria
Published: May 2010

Overexpression of βIII-tubulin is associated with resistance to tubulin-binding agents (TBA) in a range of tumor types. We previously showed that small interfering RNA silencing of βIII-tubulin expression hypersensitized non–small cell lung cancer cells to TBAs. To determine whether βIII-tubulin mediates its effect on drug-induced mitotic arrest and cell death by differentially regulating microtubule behavior, the effects of βIII-tubulin knockdown on microtubule dynamics were analyzed in H460 non–small cell lung cancer cells stably expressing green fluorescent protein-βI-tubulin. Interphase cells were examined at three vincristine and paclitaxel concentrations that (a) inhibited cell proliferation, (b) induced 5% to 10% mitotic arrest, and (c) induced 30% to 40% mitotic arrest. In the absence of either drug, βIII-tubulin knockdown caused no significant change in microtubule dynamic instability. At 2 nmol/L vincristine (IC50), overall microtubule dynamicity was significantly suppressed in βIII-tubulin knockdowns (−31.2%) compared with controls (−6.5%). Similar results were obtained with paclitaxel, suggesting that knockdown of βIII-tubulin induces hypersensitivity by enhancing stabilization of microtubule dynamics at low drug concentrations. At higher drug concentrations (≥40 nmol/L vincristine; ≥20 nmol/L paclitaxel), βIII-tubulin knockdown resulted in significantly reduced suppressive effects on microtubule dynamicity with little or no further increase in mitotic arrest, compared with control cells. Importantly, apoptosis was markedly increased by βIII-tubulin knockdown independent of further suppression of microtubule dynamics and mitotic arrest. These results show that βIII-tubulin knockdown enhances the effectiveness of TBAs through two mechanisms: suppression of microtubule dynamics at low drug concentrations and a mitosis-independent mechanism of cell death at higher drug concentrations. Mol Cancer Ther; 9(5); 1339–48. ©2010 AACR.