On the equations defining monomial curves

Let C be a monomial curve in three dimensional projective space over an algebraically closed field K of characteristic zero . We give several necessary criterions for C to be set theoretic complete intersection. Using these criterions we get several restrictions concerning the form of the equations that define C set theoretically.     

Rigid objects, triangulated subfactors and abelian localizations

We show that the abelian category $\mathsf{mod}\text{-}\mathcal{X }$ of coherent functors over a contravariantly finite rigid subcategory $\mathcal{X }$ in a triangulated category $\mathcal{T }$ is equivalent to the Gabriel–Zisman localization at the class of regular maps of a certain factor category of $\mathcal{T }$ , and moreover it can be calculated by left and right fractions. Thus we generalize recent results of Buan and Marsh. We also extend recent results of Iyama–Yoshino concerning subfactor triangulated categories arising from mutation pairs in $\mathcal{T }$ . In fact we give a classification of thick triangulated subcategories of a natural pretriangulated factor category of $\mathcal{T }$ and a classification of functorially finite rigid subcategories of $\mathcal{T }$ if the latter has Serre duality. In addition we characterize $2$ -cluster tilting subcategories along these lines. Finally we extend basic results of Keller–Reiten concerning the Gorenstein and the Calabi–Yau property for categories arising from certain rigid, not necessarily cluster tilting, subcategories, as well as several results of the literature concerning the connections between $2$ -cluster tilting subcategories of triangulated categories and tilting subcategories of the associated abelian category of coherent functors.     

Subcarrier modulation in all-optical chaotic communication systems

The enhancement of the encryption properties of chaotic signals generated by a semiconductor laser subject to optical feedback is numerically demonstrated by applying subcarrier modulation. The numerical analysis shows that the message can be very efficiently encrypted when the radio frequency carrier is within the frequency range where the chaos power density is maximized. Decoding performance is also numerically assessed considering both open- and closed-loop schemes at the receiver side. The impact of subcarrier modulation on system's performance under the influence of parameter mismatch is highlighted.     

Jak1 has a dominant role over Jak3 in signal transduction through γc-containing cytokine receptors

Genetic deficiency of Jak3 leads to abrogation of signal transduction through the common gamma chain (γc) and thus to immunodeficiency suggesting that specific inhibition of Jak3 kinase may result in immunosuppression. Jak1 cooperates with Jak3 in signaling through γc-containing receptors. Unexpectedly, a Jak3-selective inhibitor was less efficient in abolishing STAT5 phosphorylation than pan-Jak inhibitors. We therefore explored the roles of Jak1 and Jak3 kinase functionality in signaling using a reconstituted system. The presence of kinase-inactive Jak1 but not kinase-inactive Jak3 resulted in complete abolishment of STAT5 phosphorylation. Specific inhibition of the "analog-sensitive" mutant AS-Jak1 but not AS-Jak3 by the ATP-competitive analog 1NM-PP1 abrogated IL-2 signaling, corroborating the data with the selective Jak3 inhibitor. Jak1 thus plays a dominant role over Jak3 and these data challenge the notion that selective ATP-competitive Jak3 kinase inhibitors will be effective.     

Novel thermoresponsive block copolymers having different architectures—structural,rheological, thermal,and dielectric investigations

Thermoresponsive block copolymers comprising long, hydrophilic, nonionic poly(methoxy diethylene glycol acrylate) (PMDEGA) blocks and short hydrophobic polystyrene (PS) blocks are investigated in aqueous solution. Various architectures, namely diblock, triblock, and starblock copolymers are studied as well as a PMDEGA homopolymer as reference, over a wide concentration range. For specific characterization methods, polymers were labeled, either by partial deuteration (for neutron scattering studies) or by fluorophores. Using fluorescence correlation spectroscopy, critical micellization concentrations are identified and the hydrodynamic radii of the micelles, r _h ^mic , are determined. Using dynamic light scattering, the behavior of r _h ^mic in dependence on temperature and the cloud points are measured. Small-angle neutron scattering enabled the detailed structural investigation of the micelles and their aggregates below and above the cloud point. Viscosity measurements are carried out to determine the activation energies in dependence on the molecular architecture. Differential scanning calorimetry at high polymer concentration reveals the glass transition of the polymers, the fraction of uncrystallized water and effects of the phase transition at the cloud point. Dielectric relaxation spectroscopy shows that the polarization changes reversibly at the cloud point, which reflects the formation of large aggregates upon heating through the cloud point and their redissolution upon cooling.     

Brane Cosmology From Heterotic String Theory

We consider brane cosmologies within the context of five-dimensional effective actions with higher curvature corrections. The actions are compatible with bulk string amplitude calculations from heterotic string theory. We find wrapped solutions that satisfy the field equations in an approximate but acceptable manner given their complexity, where the internal, four-dimensional, scale factor is naturally inflating, having an exponential De-Sitter form. The temporal dependence of the metric components is nontrivial so that this metric cannot be factored as in a conformally flat case. The effective Planck mass is finite and the brane solutions can localize four-dimensional gravity while the four-dimensional gravitational constant varies with time. The Hubble constant can be freely specified through the initial value of the scalar field, to conform with recent data.     

Ultrasound assisted catalytic wet peroxide oxidation of phenol: kinetics and intraparticle diffusion effects

The combination of ultrasound irradiation and catalytic wet peroxide oxidation was used as a means to degrade phenol. Direct and indirect irradiation were employed, while experiments in the absence of ultrasound were used as reference. A mixed (Al-Fe) pillared clay named FAZA, was used as a catalyst in the form of powder, extrudates and crushed extrudates. Ultrasound was found to clearly enhance the extrudates performance, increasing the conversion at 4h by more than 6 times under direct and almost 11 times under indirect irradiation. This observation is attributed to the reduction of diffusion resistance within the catalyst pores. The overall sonication-catalytic wet peroxide oxidation process appears very promising for environmental purposes.     

Numerical experiments on the efficiency of local grid refinement based on truncation error estimates

Local grid refinement aims to optimise the relationship between accuracy of the results and number of grid nodes. In the context of the finite volume method no single local refinement criterion has been globally established as optimum for the selection of the control volumes to subdivide, since it is not easy to associate the discretisation error with an easily computable quantity in each control volume. Often the grid refinement criterion is based on an estimate of the truncation error in each control volume, because the truncation error is a natural measure of the discrepancy between the algebraic finite-volume equations and the original differential equations. However, it is not a straightforward task to associate the truncation error with the optimum grid density because of the complexity of the relationship between truncation and discretisation errors. In the present work several criteria based on a truncation error estimate are tested and compared on a regularised lid-driven cavity case at various Reynolds numbers. It is shown that criteria where the truncation error is weighted by the volume of the grid cells perform better than using just the truncation error as the criterion. Also it is observed that the efficiency of local refinement increases with the Reynolds number. The truncation error is estimated by restricting the solution to a coarser grid and applying the coarse grid discrete operator. The complication that high truncation error develops at grid level interfaces is also investigated and several treatments are tested.