Analysis Reveals (analysis + reveal)

Distribution by Scientific Domains
Distribution within Chemistry

Kinds of Analysis Reveals

  • regression analysis reveal

  • Selected Abstracts

    The Internet and Anti-War Activism: A Case Study of Information, Expression, and Action

    Seungahn Nah
    This case study examines how traditional and Internet news use, as well as face-to-face and online political discussion, contributed to political participation during the period leading up to the Iraq War. A Web-based survey of political dissenters (N = 307) conducted at the start of the U.S.-led invasion of Iraq provides the data used to examine the relationships among informational media use, online and face-to-face political discussion, and political participation among the respondents, who were recruited through blogs, discussion boards, and listservs opposing the Iraq war. Analyses reveal that among these respondents, Internet news use contributed to both face-to-face and online discussion about the situation in Iraq. Online and face-to-face political discussion mediated certain news media effects on anti-war political participation. The study stresses the complementary role of Web news use and online political discussion relative to traditional modes of political communication in spurring political participation. [source]

    Relationships among Strategic Capabilities and the Performance of Women-Owned Small Ventures

    Miri Lerner
    This study of small, life-style ventures owned by women focuses on the strategic, firm-level factors related to business performance. A theoretical model drawing on the resource-based theory is developed and tested empirically. The model includes strategic capabilities, management styles, and their relation to performance. It is tested empirically on a sample of 220 Israeli female business owners. Analysis reveals that life-style venture performance is highly correlated with certain aspects of the business owner's skills as well as the venture&apops;s resources. Paradoxically, the owner/managers in the sample rate their skills and their venture's resources as being weak in precisely those areas that correlate positively with business performance. These findings suggest that performance of life-style ventures owned by women depends more on marketing, financial, and managerial skills than on innovation. [source]

    Categorization bases and their influence on product category knowledge structures

    PSYCHOLOGY & MARKETING, Issue 6 2002
    José Antonio Rosa
    This study examines the relationship between categorization bases and the persistent use of specific categories in the motorcycle industry. Categorization bases are distinguished from one another and classified based on their distance from embodied experience. The relationship between the different classes that emerge and the number of years that specific category labels remain part of the market conversation is subsequently explored. The fundamental proposition is that categorization bases that are close to embodied experience, such as perceptible properties and affordances, will give rise to shorter-lived categories relative to categorization bases that are further removed from embodied experience, such as historical criteria and scientific authority. Market stories from published sources are content analyzed and coded, and used as sources of industry categories. Analysis reveals that four categorization bases,usage scripts, scientific authority, experiential wholes, and affordances,are associated with greater category persistence in the motorcycle market when used as the primary basis for categorization, whereas perceptible properties, metaphorical creations, and historical criteria were associated with lower-persistence categories. The results were not perfectly aligned with a strict distance-from-embodied-experience argument, and their implications for future research and theory are discussed. © 2002 Wiley Periodicals, Inc. [source]

    Differential admixture shapes morphological variation among invasive populations of the lizard Anolis sagrei

    MOLECULAR ECOLOGY, Issue 8 2007
    Abstract The biological invasion of the lizard Anolis sagrei provides an opportunity to study evolutionary mechanisms that produce morphological differentiation among non-native populations. Because the A. sagrei invasion represents multiple native-range source populations, differential admixture as well as random genetic drift and natural selection, could shape morphological evolution during the invasion. Mitochondrial DNA (mtDNA) analyses reveal seven distinct native-range source populations for 10 introduced A. sagrei populations from Florida, Louisiana and Texas (USA), and Grand Cayman, with 2,5 native-range sources contributing to each non-native population. These introduced populations differ significantly in frequencies of haplotypes from different native-range sources and in body size, toepad-lamella number, and body shape. Variation among introduced populations for both lamella number and body shape is explained by differential admixture of various source populations; mean morphological values of introduced populations are correlated with the relative genetic contributions from different native-range source populations. The number of source populations contributing to an introduced population correlates with body size, which appears independent of the relative contributions of particular source populations. Thus, differential admixture of various native-range source populations explains morphological differences among introduced A. sagrei populations. Morphological differentiation among populations is compatible with the hypothesis of selective neutrality, although we are unable to test the hypothesis of interdemic selection among introductions from different native-range source populations. [source]

    Phylogeography of the mountain chickadee (Poecile gambeli): diversification, introgression, and expansion in response to Quaternary climate change

    MOLECULAR ECOLOGY, Issue 5 2007
    Abstract Since the late 1990s, molecular techniques have fuelled debate about the role of Pleistocene glacial cycles in structuring contemporary avian diversity in North America. The debate is still heated; however, there is widespread agreement that the Pleistocene glacial cycles forced the repeated contraction, fragmentation, and expansion of the North American biota. These demographic processes should leave genetic ,footprints' in modern descendants, suggesting that detailed population genetic studies of contemporary species provide the key to elucidating the impact of the late Quaternary (late Pleistocene,Holocene). We present an analysis of mitochondrial DNA (mtDNA) variation in the mountain chickadee (Poecile gambeli) in an attempt to examine the genetic evidence of the impact of the late Quaternary glacial cycles. Phylogenetic analyses reveal two strongly supported clades of P. gambeli: an Eastern Clade (Rocky Mountains and Great Basin) and a Western Clade (Sierra Nevada and Cascades). Post-glacial introgression is apparent between these two clades in the Mono Lake region of Central California. Within the Eastern Clade there is evidence of isolation-by-distance in the Rocky Mountain populations, and of limited gene flow into and around the Great Basin. Coalescent analysis of genetic variation in the Western Clade indicates that northern (Sierra Nevada/Cascades) and southern (Transverse/Peninsular Ranges) populations have been isolated and evolving independently for nearly 60 000 years. [source]

    Integron-associated gene cassettes in Halifax Harbour: assessment of a mobile gene pool in marine sediments

    J. E. Koenig
    Summary The integron/gene cassette systems identified in bacteria comprise a class of genetic elements that allow adaptation by acquisition of gene cassettes. Integron gene cassettes have been shown to facilitate the spread of drug resistance in human pathogens but their role outside a clinical setting has not been explored extensively. We sequenced 2145 integron gene cassettes from four marine sediment samples taken from the vicinity of Halifax Nova Scotia, Canada, increasing the number of gene cassettes obtained from environmental microbial communities by 10-fold. Sequence analyses reveals that the majority of these cassettes encode novel proteins and that this study is consistent with previous claims of high cassette diversity as we estimate a Chao1 diversity index of ,3000 cassettes from these samples. The functional distribution of environmental cassettes recovered in this study, when compared with that of cassettes from the only other source with significant sampling (Vibrio genomes) suggests that alternate selection regimes might be acting on these two gene pools. The majority of cassettes recovered in this study encode novel, unknown proteins. In instances where we obtained multiple alleles of a novel protein we demonstrate that non-synonymous versus synonymous substitution rates ratios suggest relaxed selection. Cassette-encoded proteins with known homologues represent a variety of functions and prevalent among these are isochorismatases; proteins involved in iron scavenging. Phylogenetic analysis of these isochorismatases as well as of cassette-encoded acetyltransferases reveals a patchy distribution, suggesting multiple sources for the origin of these cassettes. Finally, the two most environmentally similar sample sites considered in this study display the greatest overlap of cassette types, consistent with the hypothesis that cassette genes encode adaptive proteins. [source]

    Prediction of butterfly diversity hotspots in Belgium: a comparison of statistically focused and land use-focused models

    Dirk Maes
    Abstract Aim, We evaluate differences between and the applicability of three linear predictive models to determine butterfly hotspots in Belgium for nature conservation purposes. Location, The study is carried out in Belgium for records located to Universal Transverse Mercator (UTM) grid cells of 5 × 5 km. Methods, We first determine the relationship between factors correlated to butterfly diversity by means of modified t -tests and principal components analysis; subsequently, we predict hotspots using linear models based on land use, climate and topographical variables of well-surveyed UTM grid cells (n = 197). The well-surveyed squares are divided into a training set and an evaluation set to test the model predictions. We apply three different models: (1) a ,statistically focused' model where variables are entered in descending order of statistical significance, (2) a ,land use-focused' model where land use variables known to be related to butterfly diversity are forced into the model and (3) a ,hybrid' model where the variables of the ,land use-focused model' are entered first and subsequently complemented by the remaining variables entered in descending order of statistical significance. Results, A principal components analyses reveals that climate, and to a large extent, land use are locked into topography, and that topography and climate are the variables most strongly correlated with butterfly diversity in Belgium. In the statistically focused model, biogeographical region alone explains 65% of the variability; other variables entering the statistically focused model are the area of coniferous and deciduous woodland, elevation and the number of frost days; the statistically focused model explains 77% of the variability in the training set and 66% in the evaluation set. In the land use-focused model, biogeographical region, deciduous and mixed woodland, natural grassland, heathland and bog, woodland edge, urban and agricultural area and biotope diversity are forced into the model; the land use-focused model explains 68% of the variability in the training set and 57% in the evaluation set. In the hybrid model, all variables from the land use-focused model are entered first and the covariates elevation, number of frost days and natural grassland area are added on statistical grounds; the hybrid model explains 78% of the variability in the training set and 67% in the evaluation set. Applying the different models to determine butterfly diversity hotspots resulted in the delimitation of spatially different areas. Main conclusions, The best predictions of butterfly diversity in Belgium are obtained by the hybrid model in which land use variables relevant to butterfly richness are entered first after which climatic and topographic variables were added on strictly statistical grounds. The land use-focused model does not predict butterfly diversity in a satisfactory manner. When using predictive models to determine butterfly diversity, conservation biologists need to be aware of the consequences of applying such models. Although, in conservation biology, land use-focused models are preferable to statistically focused models, one should always check whether the applied model makes sense on the ground. Predictive models can target mapping efforts towards potentially species-rich sites and permits the incorporation of un-surveyed sites into nature conservancy policies. Species richness distribution maps produced by predictive modelling should therefore be used as pro-active conservation tools. [source]

    Transmission network expansion planning with security constraints based on bi-level linear programming

    Hong Fan
    Abstract In deregulated power market, multiple conflicting objectives with many constraints should be balanced in transmission planning. The primary objective is to ensure the reliable supply to the demand as economically as possible. In this paper, a new bi-level linear programming model for transmission network expansion planning (TNEP) with security constraints has been proposed. The modeling improves traditional building style by adding reliability planning into economy planning as constraints, letting optimal planning strategy be more economic and highly reliable. A hybrid algorithm which integrates improved niching genetic algorithm and prime-dual interior point method is newly proposed to solve the TNEP based on bi-level programming. The advantages of the new methodology include (1) the highest reliability planning scheme can be acquired as economically as possible; (2) new model avoids the contradictions of conflicting objectives in TNEP, and explores new ideas for TNEP modeling; (3) the proposed hybrid algorithm is able to solve bi-level programming and fully manifests the merits of two algorithms as well. Simulation results obtained from two well-known systems and comparison analysis reveal that the proposed methodology is valid. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Determination of the metal ion dependence and substrate specificity of a hydratase involved in the degradation pathway of biphenyl/chlorobiphenyl

    FEBS JOURNAL, Issue 4 2005
    Pan Wang
    BphH is a divalent metal ion-dependent hydratase that catalyzes the formation of 2-keto-4-hydroxypentanoate from 2-hydroxypent-2,4-dienoate (HPDA). This reaction lies on the catabolic pathway of numerous aromatics, including the significant environmental pollutant, polychlorinated biphenyls (PCBs). BphH from the PCB degrading bacterium, Burkholderia xenoverans LB400, was overexpressed and purified to homogeneity. Atomic absorption spectroscopy and Scatchard analysis reveal that only one divalent metal ion is bound to each enzyme subunit. The enzyme exhibits the highest activity when Mg2+ was used as cofactor. Other divalent cations activate the enzyme in the following order of effectiveness: Mg2+ > Mn2+ > Co2+ > Zn2+ > Ca2+. This differs from the metal activation profile of the homologous hydratase, MhpD. UV-visible spectroscopy of the Co2+,BphH complex indicates that the divalent metal ion is hexa-coordinated in the enzyme. The nature of the metal ion affected only the kcat and not the Km values in the BphH hydration of HPDA, suggesting that cation has a catalytic rather than just a substrate binding role. BphH is able to transform alternative substrates substituted with methyl- and chlorine groups at the 5-position of HPDA. The specificity constants (kcat/Km) for 5-methyl and 5-chloro substrates are, however, lowered by eight- and 67-fold compared with the unsubstituted substrate. Significantly, kcat for the chloro-substituted substrate is eightfold lower compared with the methyl-substituted substrate, showing that electron withdrawing substituent at the 5-position of the substrate has a negative influence on enzyme catalysis. [source]

    Graphene-Based Nanoporous Materials Assembled by Mediation of Polyoxometalate Nanoparticles

    Ding Zhou
    Abstract A kind of graphene-based nanoporous material is prepared through assembling graphene sheets mediated through polyoxometalate nanoparticles. Owing to the strong interaction between graphene and polyoxometalate, 2D graphene sheets with honeycomb-latticed carbon atoms could assemble into a porous structure, in which 3D polyoxometalate nanoparticles serve as the crosslinkers. Nitrogen and hydrogen sorption analysis reveal that the as-prepared graphene-based hybrid material possesses a specific surface area of 680 m2 g,1 and a hydrogen uptake volume of 0.8,1.3 wt%. Infrared spectrometry is used to probe the electron density changes of polyoxometalate particle in the redox-cycle and to verify the interaction between graphene and polyoxometalate. The as-prepared graphene-based materials are further characterized by Raman spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. [source]

    Bottom-Up Engineering of Subnanometer Copper Diffusion Barriers Using NH2 -Derived Self-Assembled Monolayers

    Arantxa Maestre Caro
    Abstract A 3-aminopropyltrimethoxysilane-derived self-assembled monolayer (NH2SAM) is investigated as a barrier against copper diffusion for application in back-end-of-line (BEOL) technology. The essential characteristics studied include thermal stability to BEOL processing, inhibition of copper diffusion, and adhesion to both the underlying SiO2 dielectric substrate and the Cu over-layer. Time-of-flight secondary ion mass spectrometry and X-ray spectroscopy (XPS) analysis reveal that the copper over-layer closes at 1,2-nm thickness, comparable with the 1.3-nm closure of state-of-the-art Ta/TaN Cu diffusion barriers. That the NH2SAM remains intact upon Cu deposition and subsequent annealing is unambiguously revealed by energy-filtered transmission electron microscopy supported by XPS. The SAM forms a well-defined carbon-rich interface with the Cu over-layer and electron energy loss spectroscopy shows no evidence of Cu penetration into the SAM. Interestingly, the adhesion of the Cu/NH2SAM/SiO2 system increases with annealing temperature up to 7.2,J m,2 at 400,°C, comparable to Ta/TaN (7.5,J m,2 at room temperature). The corresponding fracture analysis shows that when failure does occur it is located at the Cu/SAM interface. Overall, these results demonstrate that NH2SAM is a suitable candidate for subnanometer-scale diffusion barrier application in a selective coating for copper advanced interconnects. [source]

    Biodegradable Dextran Nanogels for RNA Interference: Focusing on Endosomal Escape and Intracellular siRNA Delivery

    Koen Raemdonck
    Abstract The successful therapeutic application of small interfering RNA (siRNA) largely relies on the development of safe and effective delivery systems that are able to guide the siRNA therapeutics to the cytoplasm of the target cell. In this report, biodegradable cationic dextran nanogels are engineered by inverse emulsion photopolymerization and their potential as siRNA carriers is evaluated. The nanogels are able to entrap siRNA with a high loading capacity, based on electrostatic interaction. Confocal microscopy and flow cytometry analysis reveal that large amounts of siRNA-loaded nanogels can be internalized by HuH-7 human hepatoma cells without significant cytotoxicity. Following their cellular uptake, it is found that the nanogels are mainly trafficked towards the endolysosomes. The influence of two different strategies to enhance endosomal escape on the extent of gene silencing is investigated. It is found that both the application of photochemical internalization (PCI) and the use of an influenza-derived fusogenic peptide (diINF-7) can significantly improve the silencing efficiency of siRNA-loaded nanogels. Furthermore, it is shown that an efficient gene silencing requires the degradation of the nanogels. As the degradation kinetics of the nanogels can easily be tailored, these particles show potential for intracellular controlled release of short interfering RNA. [source]

    Comparison of low temperature mixed refrigerant cycles for separation systems

    M. Mafi
    Abstract Numerous mixed refrigerant cycles (MRCs) were developed in the past several decades in different applications. In this paper, two sets of low temperature MRCs are developed and simulated for a typical olefin plant utilizing a mixture of methane, ethane, propane and nitrogen as cycle working fluid to replace the pure ethylene refrigeration cycle that is used in conjunction with propylene refrigeration cycle in conventional plants. The key parameters of the cycles including mixture compositions and operating pressure levels are optimized to meet the objective of minimum shaftwork in compressor. The results show that different cycle configuration has different optimal mixture composition and low and high operating pressures. The results of exergy analysis reveal that the main location of the exergy loss in the cycles is the heat exchanger system. Also, the Carnot factor versus heat flow diagram is provided to identify the distribution of inefficiencies in the heat exchangers for each cycle. The simulation results show that MRCs can improve the thermodynamic performance of refrigeration system using the optimal working fluid mixture composition, optimal high and low operating pressures and optimal arrangement of the cycle components. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Getting Even or Getting Equal?

    Retributive Desires, Transitional Justice
    This article examines the effect that different policy interventions of transitional justice have on the desires of the victims of human rights violations for retribution. The retributive desires assessed in this article are conceptualized as individual, collective, and abstract demands for the imposition of a commensurate degree of suffering upon the offender. We suggest a plausible way of reducing victims' retributive desires. Instead of "getting even" in relation to the suffering, victims and perpetrators may "get equal" in relation to their respective statuses, which were affected by political crimes. The article hypothesizes that the three classes of transitional justice: (1) reparation that empowers victims by financial compensation, truth telling, and social acknowledgment; (2) retribution that inflicts punishment upon perpetrators; and (3) reconciliation that renews civic relationship between victims and perpetrators through personal contact, apology, and forgiveness; each contributes to restoring equality between victims and perpetrators, and in so doing decreases the desires that victims have for retribution. In order to test our hypotheses, we conducted a survey of former political prisoners in the Czech Republic. Results from the regression analysis reveal that financial compensation, social acknowledgement, punishment, and forgiveness are likely to reduce victims' retributive desires. [source]

    Ethnocultural Reproduction and Attitudes towards Cohabiting Relationships,

    Barbara A. Mitchell
    Se fondant sur des notions d'interculturalité et de changement social, cet article fournit une explication des différences ethnoculturelles dans les attitudes à l'endroit des relations de cohabitation hétérosexuelle chez les jeunes adultes canadiens. L'accent est mis sur la mise au jour des mécanismes clés par lesquels les groupes ethniques « reproduisent » des orientations teintées de traditionalisme ou de libéralisme à l'endroit de ces conditions de logement. L'ensemble de données utilisé dans cette recherche est tiré d'un sous-ensemble de 1 907 jeunes adultes choisis au hasard dans la Culture and Coresidence Study de 1999,2000. Les analyses à deux variables montrent de fortes différences ethnocuturelles dans la propension à déclarer que la cohabitation est acceptable, les Britanniques étant les plus favorables, suivis des Européens du Sud, des Chinois et enfin des Indo-Canadiens. Les réultats de l'analyse de régression logistique révèlent qu'une constellation de facteurs ethnocul-turels concourent à ces différences, par exemple la religiosité des jeunes adultes, le traditionalisme dans la famille et le rôle assignéà chacun des sexes, ainsi que l'usage quotidien d'une langue ethnique avec son entourage. From a cross-cultural and social change perspective, this paper explicates ethnocultural differences in attitudes towards heterosexual cohabiting relationships among Canadian young adults. The focus is on uncovering the key mechanisms by which ethnic groups "reproduce" traditional or liberal value orientations towards this living arrangement. The data set used in this research is drawn from a sub-set of 1,907 randomly-selected young adults from the 1999,2000 Culture and Coresidence Study. Bivariate analyses show strong ethnocultural differences in the propensity to report that cohabitation is acceptable, with the British group the most favourable, followed by Southern Europeans, Chinese, and finally, Indo-Canadians. Results from the logistic regression analysis reveal that a constellation of ethnocultural factors contribute to these differences. These include: young adult's religiosity, familism and gender-role traditionalism, and routine use of ethnic language with peers. [source]

    Model for Calculation of Agglomerate Sizes of Nanoparticles in a Vibro-fluidized Bed

    H. Wang
    Abstract The behavior of SiO2 nanoparticles and the effects of operating conditions on nanoparticle agglomerate sizes have been investigated under conditions created in a vibro-fluidized bed (VFB). The experimental results reveal that the vibrations imposed in the bed can suppress slugging and/or channeling, in contrast to conventional fluidization with upflow only. The vibrations imposed in the particle bed affect both the minimum fluidization velocity and the agglomerate size, both of which decrease with increases in the energy introduced to the bed by the vibrations. The effect of vibrations on the agglomeration in vibro-fluidized beds of nanoparticles depends on the critical vibration frequency corresponding to a minimum agglomerate size. Both the amplitude and the frequency of the applied vibrations have significant effects on the agglomerate size. The experimental results and the consequent analysis reveal that increasing levels of vibrations in the bed yields finer agglomerates. The Richardson-Zaki scaling law combined with Stokes law permits the prediction of agglomerate sizes and the extent of initial bed voidage. The average agglomerate sizes predicted are in good agreement with those determined experimentally. [source]

    A Mononuclear Cyclopentadiene,Iron Complex Grafted in the Supercages of HY Zeolite: Synthesis, Structure, and Reactivity

    Jinlin Long
    Abstract The reaction of ferrocene with the acidic hydroxy groups in the supercages of zeolite HY dehydrated at 673,K and the reactivity of the resultant surface species towards CO and O2 were investigated by temperature-programmed decomposition (TPD) and reduction (TPR) and IR, X-ray absorption fine structure analysis (XAFS), and X-ray photoelectron (XP) spectroscopy. In situ FTIR, TPD, TPR, and chemical analysis reveal that the Cp2Fe molecule adsorbed on the zeolite surface loses one cyclopentadienyl group under vacuum at 423,K, which leads to the formation of a well-defined mononuclear surface Fe-C5H6 complex grafted to two acidic sites and one (Si-O-Si) unit, as confirmed by the lack of Fe,Fe contributions in the EXAFS spectra. Each iron atom is coordinated, on average, to three oxygen atoms of the zeolite surface with a FeO distance of 2.00,Å and to five carbon atoms with a FeC distance of 2.09,Å. IR spectra indicate that the cyclopentadiene,iron species grafted on the surface of the zeolite is quite stable in vacuo or under an inert or hydrogen atmosphere below 423,K, and is also relatively stable under oxygen at room temperature. However, the cyclopentadiene ligand readily reacts with CO to form a compound containing carbonyl at 323,K, and even at room temperature. The single carbonyl band in the IR spectra provides evidence for the nearly uniform formation of a cyclopentadiene,iron species on the surface of the zeolite. [source]

    A Framework for Estimating Benefits of Using Auctions in Revenue Management,

    DECISION SCIENCES, Issue 3 2002
    Tim Baker
    ABSTRACT We develop a stochastic model to explore the benefits of incorporating auctions in revenue management. To the best of our knowledge the extant literature on modeling in revenue management has not considered auctions. We consider three models, namely, a traditional fixed price (non-auction) model, a pure auction model, and a hybrid auction model and evaluate their revenue performance under a variety of conditions. The hybrid approach outperforms the other two in all 24 scenarios and yields an average revenue increase of 16.1% over the next best. A surprise finding is that there is no significant difference between the performance of the fixed price and pure auction approaches. A sensitivity analysis reveals that the relative superiority of the hybrid revenue management strategy is reasonably robust. [source]

    Transcriptional control of Rohon-Beard sensory neuron development at the neural plate border

    Christy Cortez Rossi
    Abstract Rohon-Beard (RB) mechanosensory neurons are among the first sensory neurons to develop, and the process by which they adopt their fate is not completely understood. RBs form at the neural plate border (NPB), the junction between neural and epidermal ectoderm, and require the transcription factor prdm1a. Here, we show that prior to RB differentiation, prdm1a overlaps extensively with the epidermal marker dlx3b but shows little overlap with the neuroectodermal markers sox3 and sox19a. Birthdating analysis reveals that the majority of RBs are born during gastrulation in zebrafish, suggesting that it is during this period that RBs become specified. Expression analysis in prdm1a and neurogenin1 mutant and dlx3b/dlx4b morpholino-injected embryos suggests that prdm1a is upstream of dlx3b, dlx4b, and neurogenin1 at the NPB. mRNA for neurogenin1 or dlx3b/dlx4b can rescue the lack of RBs in prdm1a mutants. Based on these data, we suggest a preliminary gene regulatory network for RB development. Developmental Dynamics 238:931,943, 2009. © 2009 Wiley-Liss, Inc. [source]


    ECONOMICS & POLITICS, Issue 3 2004
    Michael J. Hiscox
    Conventional wisdom holds that increasing international capital mobility reduces incentives for firms to lobby for trade protection. This paper argues that the effects of increased international capital mobility on the lobbying incentives of firms depend critically upon levels of inter-industry mobility. General-equilibrium analysis reveals that if capital is highly industry-specific, greater international mobility among some types of specific capital may increase lobbying incentives for owners of other specific factors and thereby intensify industry-based rent-seeking in trade politics. Evidence on levels of inward and outward investment in US manufacturing industries between 1982 and 1996, and on industry lobbying activities, indicate that these effects may be quite strong. [source]

    Firm-Specific Human Capital and Governance in IPO Firms: Addressing Agency and Resource Dependence Concerns

    Jonathan D. Arthurs
    Entrepreneurs with firm-specific human capital represent both a potential source of competitive advantage and a threat to appropriate the rents that are ultimately generated by a new venture. This situation presents interesting agency and resource dependence challenges. While potential investors in these ventures will want assurances that their interests are protected, they will also want to ensure that these key entrepreneurs remain with the organization. Using agency theory and resource dependence theory, we examine the types of governance mechanisms that are implemented in firms going through an initial public offering comparing those ventures which indicate a dependence on these critical entrepreneurs versus those that do not. Our analysis reveals that ventures exhibiting dependence on key entrepreneurs are associated with higher insider and outsider ownership by the board, greater start-up experience by the board, greater use of contingent compensation, and greater use of involuntary departure agreements. [source]

    Reversible, Fine Performance Tuning of an Organometallic Molecular Wire by Addition, Ligand Replacement and Removal of Dicobalt Fragments

    Yuya Tanaka
    Abstract Communication between the two iron centres in (dithienylethyne)diyl complex 1 can be finely tuned by reversible addition to, ligand replacement at and removal from the C,C moiety in 1 of dicobalt fragments Co2(CO)n(PR3)6,n. Performance analysis reveals that disparate mechanisms are in operation for the two systems. In the case of the dicobalt adducts, indirect communication via the dicobalt steppingstone can be finely tuned by controlling the electronic structure of the dicobalt unit. [source]

    Designed Assembly and Structures and Photoluminescence of a New Class of Discrete ZnII Complexes of 1H -1,10-Phenanthroline-2-one

    Jie-Peng Zhang
    Abstract The hydrothermal reaction of 1H -1,10-phenanthroline-2-one (Hophen), zinc acetate, benzoic acid (Hba), and triethylamine (3.0 mL) yields the tetranuclear complex [Zn4(,3 -OH)2(ophen)4(ba)2] (2), which features a chair-like Zn4(,3 -OH)2 cluster with two ba ligands centrosymmetrically oriented. [(OAc){Zn3(,3 -OH)(ophen)3}(ox){Zn3(,3 -OH)(ophen)3}(OAc)] (3; ox = oxalate) was isolated when less triethylamine (1.0 mL) was used. Two Zn3(,3 -OH)(ophen)3 clusters in 3 are linked together by an oxalate to form a dumbbell-like structure in which the acetate and oxalate ligands point outward from the Zn3(,3 -OH)(ophen)3 cluster with an acute bending angle. A geometric analysis reveals that Zn3(,3 -OH)(ophen)3 and dicarboxylate with an obtuse bending angle cannot form an infinite zigzag chain, whereas the ring isomer can. With isophthalate (ipa), thiophene-2,5-dicarboxylate (tda), and 4,4,-oxybis(benzoate) (oba) instead of the acetate of 3 three new complexes, namely [{Zn3(,3 -OH)(ophen)3}(ipa)2{Zn3(,3 -OH)(ophen)3}]·0.5H2O (4), [{Zn3(,3 -OH)(ophen)3}(tda)2{Zn3(,3 -OH)(ophen)3}] (5), and [{Zn3(,3 -OH)(ophen)3}(oba)2{Zn3(,3 -OH)(ophen)3}] (6), were obtained in which two Zn3(,3 -OH)(ophen)3 clusters are linked by a pair of ipa, tda, or oba ligands to form isostructural, cluster-based 2:2 metallomacrocycles. Photoluminescence studies of 2,6 revealed that their luminescent properties are derived from ophen-based ,-,* excited states. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

    Lithium and Potassium Amides of Sterically Demanding Aminopyridines

    Natalie M. Scott
    Abstract The reaction of Grignard compounds of 1-bromo-2,4,6-diisopropylbenzene (1) or 1-bromo-2,6-dimethylbenzene (2), formed in situ, with 2,6-dibromopyridine in the presence of a catalytic amount of [(dme)NiBr2] (dme = 1,2-dimethoxyethane) and tricyclohexylphosphane (1:2 ratio) leads to the corresponding monoarylated bromopyridines. These bromopyridines undergo Pd-catalysed aryl amination (Buchwald,Hartwig amination) with 2,6-diisopropylaniline giving rise to (2,6-diisopropylphenyl)[6-(2,4,6-triisopropylphenyl)pyridin-2-yl]amine (Ap*H) and (2,6-diisopropylphenyl)[6-(2,6-dimethylphenyl)pyridin-2-yl]amine (Ap,H) (Ap = aminopyridinate). Deprotonation of Ap*H in diethyl ether using BuLi results (after workup in hexane) in a colourless crystalline material. X-ray structural analysis reveals it to be a monomeric three-coordinate lithium aminopyridinate. In toluene solution, an equilibrium between [(Ap*Li)2] (in excess at room temperature) and [Ap*Li(OEt2)] (prominent at low temperature) is observed. Reaction of Ap,H with BuLi in diethyl ether gives rise to [Ap*LiAp*Li(OEt2)]. Deprotonation of Ap*H and Ap,H using KH leads to [Ap*K]n and [Ap,K],, respectively. [Ap,K], is a rare example of a crystalline organometallic polymer, as determined by X-ray analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

    A Novel 3-D Self-Penetrating Topological Network Assembled by Mixed Bridging Ligands

    Xing Li
    Abstract The assembly of 5-sulfoisophthalic acid (H3sipa) and 4,4,-bipyridine (bpy) with Cd2+ ions gave rise to a new polymeric complex {[Cd3(sipa)2(bpy)4(H2O)2]·3H2O}n (1). X-ray diffraction analysis reveals that complex 1 has a 3-D self-penetrating network formed by the interlocking and interweaving of two types of one-dimensional chains comprising two kinds of Cd4(sipa)4 and Cd4(bpy)4 units, respectively. The sipa3, ligand serves as the connector and the Cd2+ ion as the node. Thermogravimetric analysis (TGA) and the luminescence property of 1 are discussed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

    Political parties, electoral systems and democracy: A cross-national analysis

    Models are used to explore whether the number of political parties increases a country's democracy score on the POLITY IV measure of democracy, and whether countries with proportional representation electoral systems have higher democracy scores than those without. Multiple regression analysis reveals that countries with proportional electoral systems have higher democracy scores. Countries involved in the Third Wave of democracy may find the choice of an electoral system among the most important issues in structuring a democratic government. [source]

    Damping torque analysis for DC bus implemented damping control,

    W. Du
    Abstract Damping torque analysis is a well-developed technique for understanding and studying power system oscillations. This paper presents the applications of damping torque analysis for DC bus implemented damping control in power transmission networks in two examples. The first example is the investigation of damping effect of shunt voltage source converter (VSC) based flexible AC transmission systems (FACTS) voltage control, i.e. static synchronous compensator (STATCOM) voltage control. It is shown in the paper that STATCOM voltage control mainly contributes synchronous torque and hence has little effect on the damping of power system oscillations. The second example is the damping control implemented by a battery energy storage system (BESS) installed in a power system. Damping torque analysis reveals that when BESS damping control is realized by regulating exchange of active and reactive power between the BESS and power system, respectively, BESS damping control exhibits different properties. It is concluded by damping torque analysis that BESS damping control implemented by regulating active power is better with less interaction with BESS voltage control and more robust to variations of power system operating conditions. In the paper, all analytical conclusions obtained are demonstrated by simulation results of example power systems. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    An ecdysteroid-inducible insulin-like growth factor-like peptide regulates adult development of the silkmoth Bombyx mori

    FEBS JOURNAL, Issue 5 2009
    Naoki Okamoto
    Insulin-like growth factors (IGFs) play essential roles in fetal and postnatal growth and development of mammals. They are secreted by a wide variety of tissues, with the liver being the major source of circulating IGFs, and regulate cell growth, differentiation and survival. IGFs share some biological activities with insulin but are secreted in distinct physiological and developmental contexts, having specific functions. Although recent analyses of invertebrate genomes have revealed the presence of multiple insulin family peptide genes in each genome, little is known about functional diversification of the gene products. Here we show that a novel insulin family peptide of the silkmoth Bombyx mori, which was purified and sequenced from the hemolymph, is more like IGFs than like insulin, in contrast to bombyxins, which are previously identified insulin-like peptides in B. mori. Expression analysis reveals that this IGF-like peptide is predominantly produced by the fat body, a functional equivalent of the vertebrate liver and adipocytes, and is massively released during pupa,adult development. Studies using in vitro tissue culture systems show that secretion of the peptide is stimulated by ecdysteroid and that the secreted peptide promotes the growth of adult-specific tissues. These observations suggest that this peptide is a Bombyx counterpart of vertebrate IGFs and that functionally IGF-like peptides may be more ubiquitous in the animal kingdom than previously thought. Our results also suggest that the known effects of ecdysteroid on insect adult development may be in part mediated by IGF-like peptides. [source]

    cDNA cloning and characterization of a novel calmodulin-like protein from pearl oyster Pinctada fucata

    FEBS JOURNAL, Issue 19 2005
    Shuo Li
    Calcium metabolism in oysters is a very complicated and highly controlled physiological and biochemical process. However, the regulation of calcium metabolism in oyster is poorly understood. Our previous study showed that calmodulin (CaM) seemed to play a regulatory role in the process of oyster calcium metabolism. In this study, a full-length cDNA encoding a novel calmodulin-like protein (CaLP) with a long C-terminal sequence was identified from pearl oyster Pinctada fucata, expressed in Escherichia coli and characterized in vitro. The oyster CaLP mRNA was expressed in all tissues tested, with the highest levels in the mantle that is a key organ involved in calcium secretion. In situ hybridization analysis reveals that CaLP mRNA is expressed strongly in the outer and inner epithelial cells of the inner fold, the outer epithelial cells of the middle fold, and the dorsal region of the mantle. The oyster CaLP protein, with four putative Ca2+ -binding domains, is highly heat-stable and has a potentially high affinity for calcium. CaLP also displays typical Ca2+ -dependent electrophoretic shift, Ca2+ -binding activity and significant Ca2+ -induced conformational changes. Ca2+ -dependent affinity chromatography analysis demonstrated that oyster CaLP was able to interact with some different target proteins from those of oyster CaM in the mantle and the gill. In summary, our results have demonstrated that the oyster CaLP is a novel member of the CaM superfamily, and suggest that the oyster CaLP protein might play a different role from CaM in the regulation of oyster calcium metabolism. [source]

    A steady-state modeling approach to validate an in vivo mechanism of the GAL regulatory network in Saccharomyces cerevisiae

    FEBS JOURNAL, Issue 20 2004
    Malkhey Verma
    Cellular regulation is a result of complex interactions arising from DNA,protein and protein,protein binding, autoregulation, and compartmentalization and shuttling of regulatory proteins. Experiments in molecular biology have identified these mechanisms recruited by a regulatory network. Mathematical models may be used to complement the knowledge-base provided by in vitro experimental methods. Interactions identified by in vitro experiments can lead to the hypothesis of multiple candidate models explaining the in vivo mechanism. The equilibrium dissociation constants for the various interactions and the total component concentration constitute constraints on the candidate models. In this work, we identify the most plausible in vivo network by comparing the output response to the experimental data. We demonstrate the methodology using the GAL system of Saccharomyces cerevisiae for which the steady-state analysis reveals that Gal3p neither dimerizes nor shuttles between the cytoplasm and the nucleus. [source]