bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrophilic iminosugar active‐site‐specific chaperones increase residual glucocerebrosidase activity in fibroblasts from Gaucher patients
Authors: Chang Hui‐Hwa , Asano Naoki , Ishii Satoshi , Ichikawa Yoshitaka , Fan Jian‐Qiang
Published: August 2006

Gaucher disease is an autosomal recessive lysosomal storage disorder caused by the deficient activity of glucocerebrosidase. Accumulation of glucosylceramide, primarily in the lysosomes of cells of the reticuloendothelial system, leads to hepatosplenomegaly, anemia and skeletal lesions in type I disease, and neurologic manifestations in types II and III disease. We report herein the identification of hydrophilic active‐site‐specific chaperones that are capable of increasing glucocerebrosidase activity in the cultured fibroblasts of Gaucher patients. Screening of a variety of natural and synthetic alkaloid compounds showed isofagomine, N‐dodecyl deoxynojirimycin, calystegines A3, B1, B2 and C1, and 1,5‐dideoxy‐1,5‐iminoxylitol to be potent inhibitors of glucocerebrosidase. Among them, isofagomine was the most potent inhibitor of glucocerebrosidase in vitro, and the most effective active‐site‐specific chaperone capable of increasing residual glucocerebrosidase activity in fibroblasts established from Gaucher patients with the most prevalent Gaucher disease‐causing mutation (N370S). Intracellular enzyme activity increased approximately two‐fold after cells had been incubated with isofagomine, and the increase in glucocerebrosidase activity was both dose‐dependent and time‐dependent. Western blotting demonstrated that there was a substantial increase in glucocerebrosidase protein in cells after isofagomine treatment. Immunocytochemistry revealed an improvement in the glucocerebrosidase trafficking pattern, which overlaps that of lysosome‐associated membrane protein 2 in Gaucher fibroblasts cultivated with isofagomine, suggesting that the transport of mutant glucocerebrosidase is at least partially improved in the presence of isofagomine. The hydrophilic active‐site‐specific chaperones are less toxic to cultured cells. These results indicate that these hydrophilic small molecules are suitable candidates for further drug development for the treatment of Gaucher disease.
A MULTILEVEL INTEGRATION OF PERSONALITY, CLIMATE, SELF‐REGULATION, AND PERFORMANCE
Authors: WALLACE CRAIG , CHEN GILAD
Published: August 2006

The purpose of this multilevel study was to test whether regulatory focus mechanisms (promotion focus and prevention focus; Higgins, 1997, American Psychologist, 52, 1280–1300; Higgins, 2000, American Psychologist, 55, 1217–1230) can help explain how group safety climate and individual differences in Conscientiousness relate to individual productivity and safety performance. Results, based on a sample of 254 employees from 50 work groups, showed that safety climate and conscientiousness predicted promotion and prevention regulatory focus, which in turn mediated the relationships of safety climate and Conscientiousness with supervisor ratings of productivity and safety performance. Implications for theory and research on climate, motivation, and performance and avenues for future research are discussed.
Comment on "Computational Improvements Reveal Great Bacterial Diversity and High Metal Toxicity in Soil"
Authors: Volkov Igor , Banavar Jayanth R. , Maritan Amos
Published: August 2006

Based on analysis of the reassociation kinetics of bacterial DNA in soil, Gans
et al
. (Reports, 26 August 2005, p. 1387) claimed that millions of microbe species existed in 10 grams of pristine soil and that 99.9% of the diversity was lost as a result of toxic metals. We show that the data do not support these startling conclusions unambiguously.
Mutations That Increase the Life Span of
C. elegans
Inhibit Tumor Growth
Authors: Pinkston Julie M. , Garigan Delia , Hansen Malene , Kenyon Cynthia
Published: August 2006

Mutations in
gld-1
cause lethal germline tumors in the nematode
Caenorhabditis elegans
. We find that a wide variety of mutations that extend
C. elegans
' life span confer resistance to these tumors. The long life spans of
daf-2/
insulin-receptor mutants were not shortened at all by
gld-1
mutations; we attribute this finding to decreased cell division and increased DAF-16/p53–dependent apoptosis within the tumors. Mutations that increase life span by restricting food intake or inhibiting respiration did not affect apoptosis but reduced tumor cell division. Unexpectedly, none of these longevity mutations affected mitosis in normal germlines; this finding suggests that cellular changes that lead to longevity preferentially antagonize tumor cell growth.
The First Stars in the Universe and Cosmic Reionization
Authors: Barkana Rennan
Published: August 2006

The earliest generation of stars, far from being a mere novelty, transformed the universe from darkness to light. The first atoms to form after the Big Bang filled the universe with atomic hydrogen and a few light elements. As gravity pulled gas clouds together, the first stars ignited and their radiation turned the surrounding atoms into ions. By looking at gas between us and distant galaxies, we know that this ionization eventually pervaded all space, so that few hydrogen atoms remain today between galaxies. Knowing exactly when and how it did so is a primary goal of cosmologists, because this would tell us when the early stars formed and in what kinds of galaxies. Although this ionization is beginning to be understood by using theoretical models and computer simulations, a new generation of telescopes is being built that will map atomic hydrogen throughout the universe.
p53-Mediated Inhibition of Angiogenesis Through Up-Regulation of a Collagen Prolyl Hydroxylase
Authors: Teodoro Jose G. , Parker Albert E. , Zhu Xiaochun , Green Michael R.
Published: August 2006

Recent evidence suggests that antiangiogenic therapy is sensitive to p53 status in tumors, implicating a role for p53 in the regulation of angiogenesis. Here we show that p53 transcriptionally activates the α(II) collagen prolyl-4-hydroxylase [α(II)PH] gene, resulting in the extracellular release of antiangiogenic fragments of collagen type 4 and 18. Conditioned media from cells ectopically expressing either p53 or α(II)PH selectively inhibited growth of primary human endothelial cells. When expressed intracellularly or exogenously delivered, α(II)PH significantly inhibited tumor growth in mice. Our results reveal a genetic and biochemical linkage between the p53 tumor suppressor pathway and the synthesis of antiangiogenic collagen fragments.
Response to Comment by Bunge
et al
. on "Computational Improvements Reveal Great Bacterial Diversity and High Metal Toxicity in Soil"
Authors: Gans Jason , Wolinsky Murray , Dunbar John
Published: August 2006

Bunge
et al
. claim that we underestimated the error in our analysis of bacterial diversity in noncontaminated soil. However, they used an unsatisfactory model that exhibited pathological behavior and consequently led to an exceptionally high calculated error. In contrast, the zipf distribution yielded an error estimate only 0.7 times the estimate of the total number of species (
S
), and it is more biologically relevant.
Plant Genotypic Diversity Predicts Community Structure and Governs an Ecosystem Process
Authors: Crutsinger Gregory M. , Collins Michael D. , Fordyce James A. , Gompert Zachariah , Nice Chris C. , Sanders Nathan J.
Published: August 2006

Theory predicts, and recent empirical studies have shown, that the diversity of plant species determines the diversity of associated herbivores and mediates ecosystem processes, such as aboveground net primary productivity (ANPP). However, an often-overlooked component of plant diversity, namely population genotypic diversity, may also have wide-ranging effects on community structure and ecosystem processes. We showed experimentally that increasing population genotypic diversity in a dominant old-field plant species,
Solidago altissima
, determined arthropod diversity and community structure and increased ANPP. The effects of genotypic diversity on arthropod diversity and ANPP were comparable to the effects of plant species diversity measured in other studies.
Evolutionary Paths Underlying Flower Color Variation inAntirrhinum
Authors: Whibley Annabel C. , Langlade Nicolas B. , Andalo Christophe , Hanna Andrew I. , Bangham Andrew , Thébaud Christophe , Coen Enrico
Published: August 2006

To understand evolutionary paths connecting diverse biological forms, we defined a three-dimensional genotypic space separating two flower color morphs ofAntirrhinum. A hybrid zone between morphs showed a steep cline specifically at genes controlling flower color differences, indicating that these loci are under selection.Antirrhinumspecies with diverse floral phenotypes formed a U-shaped cloud within the genotypic space. We propose that this cloud defines an evolutionary path that allows flower color to evolve while circumventing less-adaptive regions. Hybridization between morphs located in different arms of the U-shaped path yields low-fitness genotypes, accounting for the observed steep clines at hybrid zones.
A Homomolecular Porous Network at a Cu(111) Surface
Authors: Pawin Greg , Wong Kin L. , Kwon Ki-Young , Bartels Ludwig
Published: August 2006

Anthraquinone molecules self-assemble on a Cu(111) surface into a large two-dimensional honeycomb network (

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)
R
23° with pore diameters of ≈50 Å. The spontaneous formation of a pattern containing pores roughly five times larger than the size of the constituent molecules is unprecedented. The network originates from a delicate balance between substrate-mediated repulsion and intermolecular attraction involving an unusual chemical motif: hydrogen bonding between a carbonyl oxygen and an aromatic hydrogen atom. Substrate-mediated long-range adsorbate-adsorbate repulsion has been observed on anisotropic surfaces and in the context of the absence of pattern formation. Its applicability for the design of tailored molecular films is explored here.
Two-Dimensional Nematic Colloidal Crystals Self-Assembled by Topological Defects
Authors: Muševič Igor , Škarabot Miha , Tkalec Uroš , Ravnik Miha , Žumer Slobodan
Published: August 2006

The ability to generate regular spatial arrangements of particles is an important technological and fundamental aspect of colloidal science. We showed that colloidal particles confined to a few-micrometer-thick layer of a nematic liquid crystal form two-dimensional crystal structures that are bound by topological defects. Two basic crystalline structures were observed, depending on the ordering of the liquid crystal around the particle. Colloids inducing quadrupolar order crystallize into weakly bound two-dimensional ordered structure, where the particle interaction is mediated by the sharing of localized topological defects. Colloids inducing dipolar order are strongly bound into antiferroelectric-like two-dimensional crystallites of dipolar colloidal chains. Self-assembly by topological defects could be applied to other systems with similar symmetry.
Electronically Induced Atom Motion in Engineered CoCu

n

Nanostructures
Authors: Stroscio Joseph A. , Tavazza Francesca , Crain Jason N. , Celotta Robert J. , Chaka Anne M.
Published: August 2006

We have measured the quantum yield for exciting the motion of a single Co atom in CoCu

n

linear molecules constructed on a Cu(111) surface. The Co atom switched between two lattice positions during electron excitation from the tip of a scanning tunneling microscope. The tip location with highest probability for inducing motion was consistent with the position of an active state identified through electronic structure calculations. Atom motion within the molecule decreased with increased molecular length and reflected the corresponding variation in electronic structure.
Probing the Faintest Stars in a Globular Star Cluster
Authors: Richer Harvey B. , Anderson Jay , Brewer James , Davis Saul , Fahlman Gregory G. , Hansen Brad M. S. , Hurley Jarrod , Kalirai Jasonjot S. , King Ivan R. , Reitzel David , Rich R. Michael , Shara Michael M. , Stetson Peter B.
Published: August 2006

NGC 6397 is the second closest globular star cluster to the Sun. Using 5 days of time on the Hubble Space Telescope, we have constructed an ultradeep color-magnitude diagram for this cluster. We see a clear truncation in each of its two major stellar sequences. Faint red main-sequence stars run out well above our observational limit and near to the theoretical prediction for the lowest mass stars capable of stable hydrogen burning in their cores. We also see a truncation in the number counts of faint blue stars, namely white dwarfs. This reflects the limit to which the bulk of the white dwarfs can cool over the lifetime of the cluster. There is also a turn toward bluer colors in the least luminous of these objects. This was predicted for the very coolest white dwarfs with hydrogen-rich atmospheres as the formation of H
2
and the resultant collision-induced absorption cause their atmospheres to become largely opaque to infrared radiation.
Characterization of culturable bacterial populations associating withPinus sylvestris–Suillus bovinusmycorrhizospheres
Authors: Timonen Sari , Hurek Thomas
Published: August 2006

Bacterial isolations were carried out on Pinus sylvestris – Suillus bovinus mycorrhizospheres obtained directly from boreal pine forest. When samples were taken during dry weather, the numbers of bacterial colony-forming units were significantly higher in uncolonized short roots and external mycelia than in mycorrhizal roots and soil outside the mycorrhizosphere. In contrast, the colony-forming unit counts were similar in all hypogeous samples after rainy weather. Culturable bacteria were absent from most Suillus bovinus sporocarps. The bacteria isolated from all types of mycorr hizo sphere samples, i.e. short roots, mycorrhizal roots, and external mycelia, consisted primarily of Burkholderia spp., whereas most isolates from soil outside the mycorrhizosphere were identified as Paenibacillus spp. This study shows that mycorrhizal external mycelia can expand the habitat favourable for common rhizosphere bacteria into the soil far from the immediate rhizosphere. Some of these bacteria may help the trees with nitrogen acquisition, since potentially diazotrophic bacteria harbouring nitrogenase reductase (nifH) genes were isolated from mycorrhizal root tips.Key words: boreal forest soil, Burkholderia, ectomycorrhiza, nitrogen fixation, Paenibacillus.
Characterization of a HMT2-like enzyme for sulfide oxidation fromPseudomonas putida
Authors: Shibata Hiroomi , Kobayashi Shigeki
Published: August 2006

The open reading frame pp0053, which has a high homology with the sequence of mitochondrial sulfide dehydrogenase (HMT2) conferring cadmium tolerance in fission yeast, was amplified from Pseudomonas putida KT2440 and expressed in Escherichia coli JM109(DE3). The isolated and purified PP0053-Hisshowed absorption spectra typical of a flavin adenine dinucleotide (FAD)–binding protein. The PP0053-Hiscatalyzed a transfer of sulfide-sulfur to the thiophilic acceptor, cyanide, which decreased the Kmvalue of the enzyme for sulfide oxidation and elevated the sulfide-dependent quinone reduction. Reaction of the enzyme with cyanide elicited a dose-dependent formation of a charge transfer band, and the FAD-cyanide adduct was supposed to work for a sulfur transfer. The pp0053 deletion from P. putida KT2440 led to activity declines of the intracellular catalase and ubiquinone-H2oxidase. The sulfide-quinone oxidoreductase activity in P. putida KT2440 was attributable to the presence of pp0053, and the activity showed a close relevance to enzymatic activities related to sulfur assimilation.Key words: HMT2-like enzyme, pp0053, Pseudomonas putida, sulfide oxidation.
Detection and quantification of the nifH gene in shoot and root of cucumber plants
Authors: Juraeva Dilafruz , George Eckhard , Davranov Kahramon , Ruppel Silke
Published: August 2006

A real-time polymerase chain reaction (PCR) method was applied to quantify the nifH gene pool in cucumber shoot and root and to evaluate how nitrogen (N) supply and plant age affect the nifH gene pool. In shoots, the relative abundance of the nifH gene was affected neither by different stages of plant growth nor by N supply. In roots, higher numbers of diazotrophic bacteria were found compared with that in the shoot. The nifH gene pool in roots significantly increased with plant age, and unexpectedly, the pool size was positively correlated with N supply. The relative abundance of nifH gene copy numbers in roots was also positively correlated (r = 0.96) with total N uptake of the plant. The data suggest that real-time PCR-based nifH gene quantification in combination with N-content analysis can be used as an efficient way to perform further studies to evaluate the direct contribution of the N2-fixing plant-colonizing plant growth promoting bacteria to plant N nutrition.Key words: real-time PCR, biological nitrogen fixation, cucumber, N nutrition, plant growth promoting bacteria.
Poliovirus vaccine strains in sewage and river water in South Africa
Authors: Pavlov D N
Published: August 2006

Since the initiation of the global poliomyelitis eradication program in 1988, the number of wild-type polio cases decreased from 350 000 to fewer than 500, and the number of polio endemic countries declined from more than 125 to 10. The last case of polio in South Africa caused by a wild-type poliovirus (PV) occurred in 1989. The live attenuated oral poliovirus vaccine (OPV) has been effectively used in the reduction and control of poliomyelitis. However, as OPV strains are excreted in stools after vaccination, this vaccine could become a source of dissemination of PVs in the environment and the potential cause of poliomyelitis. Therefore, the aim of the study was to determine the occurrence of OPV strains in selected sewage and river water samples. During the period between 2001 and 2003, 138 samples of river water and 213 samples of settled sewage were collected from selected areas of South Africa. A total of 860 plaques were analysed, which consisted of 703 plaques from the sewage and 157 plaques from the river water samples. Using a reverse transcriptase (RT)-multiplex PCR, 49 PVs were successfully distinguished from 176 non-polio enteroviruses (NPEVs). The 176 NPEVs consisted of 50 coxsackie B2 viruses (CBV2), followed by 39 echoviruses 11 (ECV11), 25 CBV5, 21 CBV3, 15 CBV4, 14 coxsackie A6 viruses (CAV6), 7 CBV6, 2 CAV5, 2 CBV1, and 1 ECV19, which was in agreement with the prevalence of these EVs in other parts of the world. The Sabin-specific RT-triplex PCR revealed the presence of 29 Sabin PV type 1, 8 Sabin PV type 2, and 12 Sabin PV type 3 isolates. Buffalo green monkey kidney and primary liver carcinoma cell cultures allowed the amplification of a broad spectrum of EVs, whereas human epidermoid carcinoma cells were more selective for PVs. This study addressed some of the issues regarding the prevalence of OPV strains in the environment. The identification of 49 viable OPV isolates confirmed the presence and circulation of PV vaccine strains in sewage and river water. The extent of the potential health risk constituted by these OPV isolates remains to be investigated.Key words: poliovirus vaccine strains, enteroviruses, circulation, sewage, river water, molecular techniques.
Nested polymerase chain reaction for detection of pathogenic leptospires
Authors: Jouglard Sandra Denize Dorneles , Simionatto Simone , Seixas Fabiana Kommling , Nassi Fernanda Lima , Dellagostin Odir Antônio
Published: August 2006

Leptospirosis is a widespread zoonosis caused by pathogenic members of the genus Leptospira that has a great impact on human and veterinary public health. Early diagnosis of leptospirosis is important because severe lepto spiral infection can have a fulminant course. The available serological techniques for the diagnosis of leptospirosis have low sensitivity during the early stage of the disease. Efforts are being made to develop simpler, effective, efficient, and inexpensive diagnostic methods. In this work, we first evaluate a polymerase chain reaction (PCR) based method for diagnosis of leptospirosis. Primers were designed to amplify a 264 bp region within the lipL32 gene that is conserved among pathogenic Leptospira and absent in nonpathogenic species. The sensitivity and specificity of the assay were evaluated using 7 saprophytic serovars, 37 pathogenic serovars, and 15 other microorganisms. The method was very specific for pathogenic serovars, however, it lacked sensitivity. To enhance the sensitivity, another primer pair was designed to amplify a 183 bp region within the 264 bp region of the lipL32 gene and was used in a nested PCR assay. This approach was much more sensitive than conventional PCR.Key words: leptospirosis, diagnosis, nested PCR, lipL32.
Influence of nutrients, hexadecane, and temporal variations on nitrification and exopolysaccharide composition of river biofilms
Authors: Chénier Martin R , Beaumier Danielle , Roy Réal , Driscoll Brian T , Lawrence John R , Greer Charles W
Published: August 2006

Biofilms were cultivated on polycarbonate strips in rotating annular reactors using South Saskatchewan River water during the fall of 1999 and the fall of 2001. The reactors were supplemented with carbon (glucose), nitrogen (NH4Cl), phosphorus (KH2PO4), or combined nutrients (CNP), with or without hexadecane. The impact of these treatments on nitrification and on the exopolysaccharide composition of river biofilms was determined. The results showed that the biofilms had higher NH4+oxidation, NO3–production, and N2O production activities in fall 1999 than fall 2001 when grown with CNP but had higher activities in fall 2001 than fall 1999 when grown with individual nutrients. The exopolysaccharide amounts and proportions were generally higher in fall 1999 than fall 2001, as a consequence of the higher nutrient levels in the river water in the first year of this study. The addition of P and especially CNP stimulated NH4+oxidation by the biofilms, showing a P limitation in this river ecosystem. The presence of hexadecane negatively affected these activities and lowered the amounts of exopolysaccharides in CNP and P biofilms in fall 1999 but increased the biofilm activities and exopolysaccharide amounts in CNP biofilm in fall 2001. Antagonistic, synergistic, and independent effects between nutrients and hexadecane were also observed. This study demonstrated that the biofilm autotrophic nitrification activity in the South Saskatchewan River was limited by P, that this activity and the exopolysaccharide amounts and proportions were dependent on the nutrient concentrations in the river water, and suggested that exopolysaccharides may play a protective role for biofilm microorganisms against toxic pollutants.Key words: river biofilms, nitrification, nutrients, hexadecane, exopolysaccharides.
AN ALGORITHM TO PERFORM POVMS THROUGH NEUMARK THEOREM: APPLICATION TO THE DISCRIMINATION OF NON-ORTHOGONAL PURE QUANTUM STATES
Authors: RABELO WILSON R. M. , RODRIGUES ALEXANDRE G. , VIANNA REINALDO O.
Published: August 2006

We consider a protocol to perform the optimal quantum state discrimination of N linearly independent non-orthogonal pure quantum states and present a computational code. Through the extension of the original Hilbert space, it is possible to perform an unitary operation yielding a final configuration, which gives the best discrimination without ambiguity by means of von Neumann measurements. Our goal is to introduce a detailed general mathematical procedure to realize this task by means of semidefinite programming and norm minimization. The former is used to fix which is the best detection probability amplitude for each state of the ensemble. The latter determines the matrix which leads the states to the final configuration. In a final step, we decompose the unitary transformation in a sequence of two-level rotation matrices.
NONEQUILIBRIUM MULTICRITICAL BEHAVIOR IN ANISOTROPIC HEISENBERG FERROMAGNET DRIVEN BY OSCILLATING MAGNETIC FIELD
Authors: ACHARYYA MUKTISH
Published: August 2006

The Heisenberg ferromagnet (uniaxially anisotropic along z-direction), in the presence of time dependent (but uniform over space) magnetic field, is studied by Monte Carlo simulation. The time dependent magnetic field was taken as elliptically polarised in such a way that the resulting field vector rotates in the XZ-plane. In the limit of low anisotropy, the dynamical responses of the system are studied as functions of temperature and the amplitudes of the magnetic field. As the temperature decreases, it was found that the system undergoes multiple dynamical phase transitions. In this limit, the multiple transitions were studied in details and the phase diagram for this observed multicritical behavior was drawn in field amplitude and temperature plane. The natures (continuous/discontinuous) of the transitions are determined by the temperature variations of fourth-order Binder cumulant ratio and the distributions of order parameters near the transition points. The transitions are supported by finite size study. The temperature variations of the variances of dynamic order parameter components (for different system sizes) indicate the existence of diverging length scale near the dynamic transition points. The frequency dependences of the transition temperatures of the multiple dynamic transition are also studied briefly.
FERROMAGNETIC FLUID AS A MODEL OF SOCIAL IMPACT
Authors: FRONCZAK PIOTR , FRONCZAK AGATA , HOŁYST JANUSZ A.
Published: August 2006

The paper proposes a new model of spin dynamics which can be treated as a model of sociological coupling between individuals. Our approach takes into account two different human features: Gregariousness and individuality. We will show how they affect a psychological distance between individuals and how the distance changes the opinion formation in a social group. Apart from its sociological aplications the model displays the variety of other interesting phenomena like self-organizing ferromagnetic state or a second order phase transition and can be studied from different points of view, e.g., as a model of ferromagnetic fluid, complex evolving network or multiplicative random process.
GROUND STATE PROPERTIES OF TWO SPIN MODELS WITH EXACTLY KNOWN GROUND STATES ON THE SQUARE LATTICE
Authors: SINDERMANN A. , LÖW U. , ZITTARTZ J.
Published: August 2006

We introduce a new two-dimensional model with diagonal four spin exchange and an exactly known ground-state. Using variational ansätze and exact diagonalisation we calculate upper and lower bounds for the critical coupling of the model. Both for this model and for the Shastry–Sutherland model we study periodic systems up to system size 6×6.
COMPARATIVE STUDY OF THE MULTIQUADRIC AND THIN-PLATE SPLINE RADIAL BASIS FUNCTIONS FOR THE TRANSIENT-CONVECTIVE DIFFUSION PROBLEMS
Authors: DURMUS A. , BOZTOSUN I. , YASUK F.
Published: August 2006

The numerical solutions of the unsteady transient-convective diffusion problems are investigated by using multiquadric (MQ) and thin-plate spline (TPS) radial basis functions (RBFs) based on mesh-free collocation methods with global basis functions. The results of radial basis functions are compared with the mesh-dependent boundary element and finite difference methods as well as the analytical solution for high Péclet numbers. It is reported that for low Péclet numbers, MQ-RBF provides excellent agreement, while for high Péclet numbers, TPS-RBF is better than MQ-RBF.
FINITE-SIZE CORRECTIONS TO CORRELATION FUNCTION AND SUSCEPTIBILITY IN 2D ISING MODEL
Authors: KAUPUŽS J.
Published: August 2006

Transfer matrix calculations of the critical two-point correlation function in 2D Ising model on a finite-size [Formula: see text] lattice with periodic boundaries along 〈11〉 direction are extended to L = 21. A refined analysis of the correlation function in 〈10〉 crystallographic direction at the distance r = L indicates the existence of a nontrivial finite-size correction of a very small amplitude with correction-to-scaling exponent ω < 2 in agreement with our foregoing study for L ≤ 20. Here we provide an additional evidence and show that amplitude a of the multiplicative correction term 1 + aL-ωis about -3.5·10-8if ω = 1/4 (the expected value). We calculate also the susceptibility for L ≤ 18 in order to compare our numerical estimates for the constant background contribution with the known very precise value and to look for possible nontrivial corrections to scaling. The numerical analysis reveals a perfect agreement for the background term, as well as shows that the nontrivial correction term, detected by our analysis in the correlation function, likely cancels in the susceptibility.
FINDING OUT WHO THE CROOKS ARE — TAX EVASION WITH SEQUENTIAL AUDITING
Authors: BAYER RALPH-C.
Published: August 2006

This paper investigates multi-item moral hazard with auditing contests.s Although the presented model is widely applicable, we choose tax evasion as an exemplary application. We introduce a tax-evasion model where tax authority and taxpayer invest in detection and concealment. The taxpayers have multiple potential income sources and are heterogeneous with respect to their evasion scruples. The tax authority — unable to commit to an audit strategy — observes a tax declaration and chooses its auditing efforts. We show that the tax authority prefers to audit source by source until it finds evidence for evasion to conduct a full-scale audit thereafter. Furthermore, we provide an explanation for why economic actors engage in both the formal and informal sector at the same time.
ON ASPECTS OF FOOD SAFETY AND INTERNATIONAL TRADE
Authors: MACLAREN DONALD
Published: August 2006

International supply chains in the food industry have lengthened in recent years and new sources of risk have arisen. With increased consumers' incomes, perceptions about food safety have become sharper and food safety has become an important issue in public policy both domestically and internationally. The safety of food is a credence characteristic which gives rise to a particular form of market failure involving either asymmetric information and moral hazard or symmetric imperfect information. An example from a recent experience in the UK was used to illustrate the issue of moral hazard, as well as the possible responses to it. A partial equilibrium model of an open economy was developed to investigate how the moral hazard problem that is caused for importing firms by the actions of exporting firms could be solved by the market rather than by government intervention.
COMPARATIVE STATICS ON ONLINE COMPETITION AND INTERNET TAXATION
Authors: LEE SANG-HO
Published: August 2006

This paper analyzes price competition in a differentiated goods market between online and offline firms, and compares equilibrium prices, market demands, and profits of the firms. We also investigate the effects of a commodity tax on offline firms and Internet taxes on online firm regarding government tax revenue. We demonstrate that tax revenue depends not only on the relative size of online access and offline transportation costs, but also on the maturity of e-commerce. Under the Internet Tax Freedom Act, in particular, we show that (i) when the offline commodity tax is large, tax revenue decreases with the maturity of e-commerce market increases, and (ii) when the offline commodity tax is small, tax revenue decreases first and then increases with the maturity of e-commerce market.
THE ROLE OF FOREIGN DIRECT INVESTMENT IN INDIA'S SERVICES EXPORTS: AN EMPIRICAL INVESTIGATION
Authors: SRIVASTAVA SADHANA
Published: August 2006

Export-oriented FDI is increasingly being perceived as an instrumental tool to strengthen country's export-competitiveness in developing countries. The theoretical literature suggests that both FDI and trade can be substitutive or complementary to each other depending on the nature of investment, industry-mix and host country's characteristics. In this context, the experience of the Indian economy is particularly instructive. Although some empirical studies have supported the view that FDI inflows in the Indian economy have not been export-oriented, it is important to note that none of these have studied the impact of FDI inflows on service exports, in spite of service sector emerging as a key driver of India's export growth. This paper examines the causal relationship between FDI inflows and service exports in the Indian economy during the post liberalization period since 1991. It uses a multivariate VAR framework for the analysis. The empirical results confirm the presence of short-run unidirectional Granger causality from FDI to services exports in the Indian economy.
COMPETITION POLICY AND LAW IN ASEAN
Authors: SIVALINGAM G.
Published: August 2006

The focus of this paper is on competition policy and law in the ASEAN countries. The paper begins with a descriptive evaluation of competition policy in the ASEAN countries. We then look at the effect of economic structure on the probability of early adoption of competition law among the ASEAN countries after which the competition laws of the ASEAN countries are evaluated in terms of objectives, jurisdictional exception, horizontal agreements, vertical agreements, definition and abuse of dominant position and mergers. We find that the competition laws of the four ASEAN countries that have implemented competition law are not completely harmonized.
INNOVATION, IMITATION AND ENTREPRENEURSHIP
Authors: YONG GRACE LI ANN , HO KONG WENG
Published: August 2006

This paper analyzes the gradual shift in the technological paradigm of an economy as it approaches the world technology frontier. The model developed in this paper consists of firms which employ skilled workers as an important input in technological advancement, but the novel feature here is the entrepreneur, who is the brain of technological progress. The entrepreneur has to decide to undertake either imitative or innovative activities, of which decision both affects and is affected by the country's distance to frontier. Specifically, the entrepreneur needs to have a minimum ability threshold level in order to carry out innovation. This endogenous threshold level falls as the economy moves closer to the technological frontier, enabling more entrepreneurs to be engaged in an innovation-based strategy, and consequently, moving the economy from a technological structure that is based on imitation of foreign technologies to one where domestic innovation dominates. The transitional dynamics of the model shows that there exists a steady state distance from the world frontier that countries will eventually converge to. We also find that it is possible for countries under certain conditions, to be trapped in a regime carrying out only imitation of world technologies.
DICHOTOMOUS MARKOV NOISE: EXACT RESULTS FOR OUT-OF-EQUILIBRIUM SYSTEMS
Authors: BENA IOANA
Published: August 2006

Nonequilibrium systems driven by additive or multiplicative dichotomous Markov noise appear in a wide variety of physical and mathematical models. We review here some prototypical examples, with an emphasis on analytically-solvable situations. In particular, it has escaped attention till recently that the standard results for the long-time properties of such systems cannot be applied when unstable fixed points are crossed in the asymptotic regime. We show how calculations have to be modified to deal with these cases and present a few relevant applications — the hypersensitive transport, the rocking ratchet, and the stochastic Stokes' drift. These results reinforce the impression that dichotomous noise can be put on par with Gaussian white noise as far as obtaining analytical results is concerned. They convincingly illustrate the interplay between noise and nonlinearity in generating nontrivial behaviors of nonequilibrium systems and point to various practical applications.
SUBSTITUTION EFFECT IN Pr-DOPED YBCO
Authors: ZHANG L. , WANG M. , XU Y. Y.
Published: August 2006

A series of samples of Y 1-x Pr x Ba 2 Cu 3 O y ( YPrBCO ) with 0.05 ≤ x ≤ 0.6 was synthesized and characterized by DC magnetization, X-ray diffraction (XRD), and Rietveld refinement. It is found that besides Pr substitution for Y , a part of Pr substituted for Ba in YBa 2 Cu 3 O y (YBCO), and the amount of Pr in the Y and Ba positions, respectively, is estimated by the refinement with the help of bond valence sum (BVS) calculation. By comparing the correlation of structural changes such as Ba-O (4) and Cu (1, 2)- O (4) bond lengths and superconductivity between our system with the reference system where Pr just replaces Y , structural evidences are found to explain Pr substitution for Ba suppresses Tc more strongly than that for Y .
NONLINEAR TE SURFACE WAVES IN A LAYERED ANTIFERROMAGNET — SUPERCONDUCTOR WAVEGUIDE STRUCTURE
Authors: HAMADA M. S. , SHABAT M. M. , JÄGER D.
Published: August 2006

This paper describes the theoretical characteristics of TE nonlinear transverse electric surface waves propagating at microwave frequencies in a layered structure of superconductor film bounded by an antiferromagnet substrate and a linear ferrite cover. The effects of the operating angular frequency and temperature of superconductor on the dispersion characteristics have been examined. The power flow has also been studied as a function of the reduced phase and attenuation constants.
EFFECTS OF A STRONG MAGNETIC FIELD ON INTERFACE EXCITON WITH A HOLE CONFINED IN A QUANTUM WELL
Authors: NGO VAN THANH , NGUYEN AI VIET
Published: August 2006

We study by the variational method the effects of external magnetic field on the interface exciton with a hole confined in the quantum well. The main parameters of our model are: the distance d between the interface plane and center of the quantum well, the parameters of quantum well (the half width a and the height V0) and magnetic length λ. We obtained the binding energy and effective optical efficiency of this type of interface exciton. This model can be developed to investigate the properties of two-dimensional excitons in coupled quantum well.1
Coalescence of lateral spreading magma ascending through dykes: a mechanism to form a granite canopy (El Hongo pluton, Sierras Pampeanas, Argentina)
Authors: D'Eramo F. , Pinotti L. , Tubía J.M. , Vegas N. , Aranguren A. , Tejero R. , Gómez D.
Published: August 2006

This study deals with the structure of the El Hongo trondhjemite, a ENE–WSW elongate pluton belonging to the Famatinian magmatic arc that developed from Late Cambrian to Silurian times in the Sierras Pampeanas (Argentina). Anisotropy of magnetic susceptibility (AMS) measurements combined with structural and microstructural data permit the correlation of magmatic and magnetic fabrics within this ferromagnetic pluton. Magnetic foliations strike north–south and dip steeply west but in the marginal facies the foliation becomes parallel to the ENE–WSW pluton contacts. Magnetic lineations mostly trend north–south and plunge SE. Gravity data reveal that the pluton is in the form of a very thin horizontal sheet resting on two north–south-trending root zones detected below the central portion of the pluton. These root zones represent feeder dykes that exploited tension fractures. The emplacement of the El Hongo pluton took place during the action of a buried sinistral shear zone, parallel to the elongation of the pluton, corresponding to a transfer fault associated with the late extensional exhumation of the Famatinian domain. The emplacement of other Famatinian granites of the Sierras Pampeanas could be related to similar late shear zones.
The morphology of intrusion-related vent structures and their implications for constraining the timing of intrusive events along the NE Atlantic margin
Authors: MØller Hansen Dorthe
Published: August 2006

Intrusion-related vent structures found within Palaeocene sediments and near the Palaeocene–Eocene transition in basins along the NE Atlantic margin have been studied in detail using 3D seismic data. The vents formed at the palaeo-seabed as a result of sill intrusion and the vent fill ranges in composition from entirely remobilized sedimentary to dominantly magmatic. The vents are commonly developed above sill edges and crests in sills to which they are linked by pipe- and diatreme-like structures. The vents also develop above the upper tips of deep-seated faults and at fault intersections. The vents can be used to constrain the approximate timing of igneous sill intrusion and duration of hydrothermal activity. It is estimated that using the seismically constrained stratigraphic context of these vents to establish the timing of sill emplacement is associated with an uncertainty of >100 ka and up to as much as 800 ka. Interpretation of the vents indicates that sill intrusion took place during a number of discrete phases within the Palaeocene and earliest Eocene. These structures and their timing of formation have important implications for climate change studies, basin-scale processes including fluid flow and diagenesis, as well as hydrocarbon exploration.
Two-phase orogenic convergence in the external and internal SW Alps
Authors: Ford Mary , Duchêne Stéphanie , Gasquet Dominique , Vanderhaeghe Olivier
Published: August 2006

The NW–SE-trending sector of the SW Alps includes the Dora Maira massif where Tertiary eclogites record ultrahigh pressures and rapid exhumation. Along a NE–SW crustal cross-section (Italy–France) compiled pressure–temperature–time data in internal zones are correlated with Tertiary stratigraphy in external zones to reconstruct orogen evolution, revealing a coherent two-phase convergence history. During the first, subduction–accretion phase (Eocene, 55–34 Ma) rapid north–south plate convergence caused the subduction and exhumation of high-pressure and ultrahigh-pressure (UHP) rocks in a steady-state subduction channel. This coincided with the north to NNW migration of an underfilled flexural basin across the European foreland. Nappe stacking within the subduction channel did not create significant relief, implying that primarily subduction forces generated this flexural basin. From 34 Ma onward, the second, collisional phase was characterized by slower NW–SE plate convergence. The internal units of the SW Alps underwent considerable anticlockwise rotation as they became involved in a NW–SE-oriented sinistral transpression zone between the European and Adriatic plates. To the north of the orogen the North Alpine Foreland Basin became overfilled as a result of high sediment supply from increasing orogen relief. In contrast, in SE France active flexure of the European plate appears to have ceased and sedimentation became limited to small thrust-sheet-top basins created by continuing gentle NE–SW shortening. Internal units were exhumed slowly from depths of
c
. 20 km, principally by erosion. In the SW Alps, the transition between these two phases was marked by the rapid subduction and exhumation of the Dora Maira UHP unit. Assuming lithostatic pressure, this unit would have been exhumed from 100 km depth, requiring a rate that exceeds that generated by plate convergence. Therefore, either exhumation was accelerated by additional stresses (locally generated by transpression, slab breakoff or high density contrasts) or, more controversially, the ultrahigh pressure occurred at a considerably shallower depth as a result of local overpressure.
Stable isotope transfer in open and closed system across chemically contrasted boundaries: metacarbonate–granitoid contacts in the Quérigut magmatic complex (Eastern Pyrenees, France)
Authors: DurandD Cyril , Boulvais Philippe , Marquer Didier , Rossy Michel
Published: August 2006

The processes of stable isotope transfer between chemically contrasted boundaries are examined for two metacarbonate–granitoid contacts in the Quérigut complex, Pyrénées, France. External contacts, between the sedimentary basement and granitic intrusions, behaved like a fluid-dominated open system whereas septa contacts, between carbonate septa and the host granitoids, behaved like a closed system with respect to external fluids. Along external contacts, skarns of several decimetres to several metres were developed. δ
18
O values of calcite, buffered at 13.5–14‰, suggest an advection of metamorphic aqueous fluid with a minor contribution of low δ
13
C CO
2
during skarn formation. Internal contacts are characterized by a thin centimetre-sized skarn layer. δ
13
C and δ
18
O values of calcite follow an evolution explained by decarbonation processes alone. δ
18
O exchange profiles across the contact show a typical diffusion profile with their inflection points slightly displaced towards the metacarbonate side, interpreted as a limited influx of magmatic fluids. Moreover, the shape of septa profiles varies according to the thermal energy budget induced by the intrusive rock: more isotopic alteration appears where the intrusion size is larger.
Thrust sequences and the significance of low-angle, out-of-sequence faults in the northernmost Moine Nappe and Moine Thrust Zone, NW Scotland
Authors: Holdsworth R.E. , Strachan R.A. , Alsop G.I. , Grant C.J. , Wilson R.W.
Published: August 2006

In common with most thrust belts, the Moine Thrust Zone, Scotland, preserves a foreland-propagating sequence of thrusting. However, significant examples of local to regional overstep sequences are also recognized and their interpretation remains controversial. Remapping of the northernmost Moine Thrust Zone has defined a thick belt of mylonites in the centre of which lies the ductile WNW-directed Moine Thrust. The base of the mylonite belt, however, is marked by a regionally significant, low-angle, west-directed brittle fault, here termed the Lochan Riabhach Thrust, that truncates thrust-related structures in its footwall. Comparison of the tectonic stratigraphy of the mylonite belt with that preserved in a downfaulted outlier to the west at Durness indicates that the Lochan Riabhach Thrust cuts down-section in its footwall and therefore appears to be extensional. Locally, it is unequivocally breached by underlying imbricate thrusts. We prefer to interpret the Lochan Riabhach ‘Thrust’ as an extensional fault that formed during a hiatus in thrust stacking. We relate this faulting episode to the changes in the stability of the evolving orogenic wedge and reiterate that such extensional faults may be common, although possibly unrecognized, features in many other thrust belts.
Crustal thinning, mantle exhumation and serpentinization in the Porcupine Basin, offshore Ireland: evidence from wide-angle seismic data
Authors: O'Reilly B.M. , Hauser F. , Ravaut C. , Shannon P.M. , Readman P.W.
Published: August 2006

New wide-angle seismic data were gathered along a 230 km long profile that runs east–west across a deep structural feature in the Porcupine Basin, offshore Ireland, known as the Porcupine Arch. Ocean bottom seismometers were deployed at 3–4 km intervals and seismic sources fired every 120 m along it. Prominent primary and secondary arrivals indicate that the continental crust is extremely thin (locally less than 2 km) across the basin centre. The sedimentary succession is up to 12 km thick and comprises three distinctive seismic layers. The two uppermost layers are interpreted as mostly a post-rift succession of Cretaceous and Cenozoic strata. The lowest layer thins rapidly towards the basin centre and is interpreted as a succession of predominantly Jurassic synrift sediments. A strong asymmetry in both the geometry of the crust and the sedimentary layers is probably related to a simple shear mode of extension and the subsidence that it induced. Crustal thinning is far greater than in the adjacent Rockall Basin and local exhumation of continental mantle lithosphere may have occurred in parts of the Porcupine Basin. Low P
n
velocities beneath the Porcupine Arch are compatible with larger amounts of mantle serpentinization than in the Rockall Basin.