1,470 research outputs found

    The key aspects of innovation-oriented regional industrial and economic policy

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    Integration processes taking place in the economy, the new requirements to enhance the effectiveness of production during international competition as well as the need to ensure the social conditions lead to the development and implementation of innovation-oriented regional industrial and economic policy, which in its turn, requires adopting substantial organizational and economic recommendations

    Correlated time-dependent transport through a 2D quantum structure

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    We use a generalized master equation (GME) to describe the nonequilibrium magnetotransport of interacting electrons through a broad finite quantum wire with an embedded ring structure. The finite quantum wire is weakly coupled to two broad leads acting as reservoirs of electrons. The mutual Coulomb interaction of the electrons is described using a configuration interaction method for the many-electron states of the central system. We report some non-trivial interaction effects both at the level of time-dependent filling of states and on the time-dependent transport. We find that the Coulomb interaction in this non-trivial geometry can enhance the correlation of electronic states in the system and facilitate it's charging in certain circumstances in the weak coupling limit appropriate for the GME. In addition, we find oscillations in the current in the leads due to the correlations oscillations caused by the switched-on lead- system coupling. The oscillations are influenced and can be enhanced by the external magnetic field and the Coulomb interaction.Comment: RevTeX (pdf-LaTeX), 10 pages with 15 included jpg figure

    Reconstruction of Random Colourings

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    Reconstruction problems have been studied in a number of contexts including biology, information theory and and statistical physics. We consider the reconstruction problem for random kk-colourings on the Δ\Delta-ary tree for large kk. Bhatnagar et. al. showed non-reconstruction when Δ12klogko(klogk)\Delta \leq \frac12 k\log k - o(k\log k) and reconstruction when Δklogk+o(klogk)\Delta \geq k\log k + o(k\log k). We tighten this result and show non-reconstruction when Δk[logk+loglogk+1ln2o(1)]\Delta \leq k[\log k + \log \log k + 1 - \ln 2 -o(1)] and reconstruction when Δk[logk+loglogk+1+o(1)]\Delta \geq k[\log k + \log \log k + 1+o(1)].Comment: Added references, updated notatio

    Percolation in invariant Poisson graphs with i.i.d. degrees

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    Let each point of a homogeneous Poisson process in R^d independently be equipped with a random number of stubs (half-edges) according to a given probability distribution mu on the positive integers. We consider translation-invariant schemes for perfectly matching the stubs to obtain a simple graph with degree distribution mu. Leaving aside degenerate cases, we prove that for any mu there exist schemes that give only finite components as well as schemes that give infinite components. For a particular matching scheme that is a natural extension of Gale-Shapley stable marriage, we give sufficient conditions on mu for the absence and presence of infinite components

    Computational investigations of the electronic structure of molecular actinide compounds

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    In this PhD thesis the electronic structure of a range of actinide compounds has been investigated using density functional theory. The reason for using DFT instead of other methods is mainly due to the size of the compounds which makes multireference calculations prohibitively expensive, but also to make comparisons with previously calculated DFT results. The first chapter presents the basic concepts of electronic structure theory and the chemical properties of the actinides and lanthanides. The theoretical foundation of DFT and the consequences of relativity are also introduced. In the second chapter the bonding in mixed MUCl6, MUCl8 2-, NpReCl8 2- and PuOsC NpReCl8 2- (M = Mo, W) systems is investigated and compared with previous work on the M2Cl6, M2C NpReCl8 2- U2Cl6 and U2C NpReCl8 2- systems. The study shows that the total bonding energy in the mixed compounds is the average of the two “pure” compounds. The third chapter deals with systems of plenary or lacunary Keggin phosphomolybdate coordination to actinide (Th), lanthanide (Ce, La, Lu) and transition metal (Hf, Zr) cations: [PMo12O40]3-, [PMo11O39]2 14-, [PMo12O40]2 6- and [PMo11O39][PMo12O40]10-. These large, highly anionic systems proved to be very challenging computationally. The main result of the study confirms that the bonding is ionic and that there are few differences in the behaviour of the transition metals. In the fourth chapter the electronic spectrum of NpO2 2+, NpO2Cl4 2- and NpO2(OH)4 2- is calculated using time dependent DFT. TDDFT has proved adequate for the uranium analogues of these systems and this extends previous work on f0 systems to f1 systems. The results show that TDDFT is in poor agreement with both experimental results and multireference calculations for these compounds. In chapter five, group 15 and 16 uranyl analogues have been investigated. For the UE2 (E = O, S, Se, Te) analogues the geometry bends for all chalcogens heavier than O. The UE2 2+ analogues remain linear all the way down group 16. In U(NCH3)2 2+ the formation of a {pi} “back bone” along the axis of the molecule was noted. The {sigma}-bonding valence MOs stabilize while the {pi} MOs are destabilized down group 15 and 16. Chapter six is a summary of the results in this thesis and an outlook on potential future work

    Molecular Basis of Enhanced Activity in Factor VIIa-Trypsin Variants Conveys Insights into Tissue Factor-mediated Allosteric Regulation of Factor VIIa Activity

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    The complex of coagulation factor VIIa (FVIIa), a trypsin-like serine protease, and membrane-bound tissue factor (TF) initiates blood coagulation upon vascular injury. Binding of TF to FVIIa promotes allosteric conformational changes in the FVIIa protease domain and improves its catalytic properties. Extensive studies have revealed two putative pathways for this allosteric communication. Here we provide further details of this allosteric communication by investigating FVIIa loop swap variants containing the 170 loop of trypsin that display TF-independent enhanced activity. Using x-ray crystallography, we show that the introduced 170 loop from trypsin directly interacts with the FVIIa active site, stabilizing segment 215–217 and activation loop 3, leading to enhanced activity. Molecular dynamics simulations and novel fluorescence quenching studies support that segment 215–217 conformation is pivotal to the enhanced activity of the FVIIa variants. We speculate that the allosteric regulation of FVIIa activity by TF binding follows a similar path in conjunction with protease domain N terminus insertion, suggesting a more complete molecular basis of TF-mediated allosteric enhancement of FVIIa activity

    Strict inequalities of critical values in continuum percolation

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    We consider the supercritical finite-range random connection model where the points x,yx,y of a homogeneous planar Poisson process are connected with probability f(yx)f(|y-x|) for a given ff. Performing percolation on the resulting graph, we show that the critical probabilities for site and bond percolation satisfy the strict inequality pcsite>pcbondp_c^{\rm site} > p_c^{\rm bond}. We also show that reducing the connection function ff strictly increases the critical Poisson intensity. Finally, we deduce that performing a spreading transformation on ff (thereby allowing connections over greater distances but with lower probabilities, leaving average degrees unchanged) {\em strictly} reduces the critical Poisson intensity. This is of practical relevance, indicating that in many real networks it is in principle possible to exploit the presence of spread-out, long range connections, to achieve connectivity at a strictly lower density value.Comment: 38 pages, 8 figure

    Impact of inhaled corticosteroids on growth in children with asthma: systematic review and meta-analysis

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    Background: Long-term inhaled corticosteroids (ICS) may reduce growth velocity and final height of children with asthma. We aimed to evaluate the association between ICS use of >12 months and growth. Methods: We initially searched MEDLINE and EMBASE in July 2013, followed by a PubMed search updated to December 2014. We selected RCTs and controlled observational studies of ICS use in patients with asthma. We conducted random effects meta-analysis of mean differences in growth velocity (cm/year) or final height (cm) between groups. Heterogeneity was assessed using the I2 statistic. Results: We found 23 relevant studies (twenty RCTs and three observational studies) after screening 1882 hits. Meta-analysis of 16 RCTs showed that ICS use significantly reduced growth velocity at one year follow-up (mean difference -0.48 cm/year (95% CI -0.66 to -0.29)). There was evidence of a dose-response effect in three RCTs. Final adult height showed a mean reduction of -1.20 cm (95% CI -1.90 cm to -0.50 cm) with budesonide versus placebo in a high quality RCT. Meta-analysis of two lower quality observational studies revealed uncertainty in the association between ICS use and final adult height, pooled mean difference -0.85 cm (95% CI -3.35 to 1.65). Conclusion: Use of ICS for >12 months in children with asthma has a limited impact on annual growth velocity. In ICS users, there is a slight reduction of about a centimeter in final adult height, which when interpreted in the context of average adult height in England (175 cm for men and 161 cm for women), represents a 0.7% reduction compared to non-ICS users
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