Thermodynamic analysis of inverted bifurcation

We present a thermodynamic analysis of inverted bifurcation in binary mixtures heated from below. From this analysis it follows that an inverted bifurcation is caused by the competition between a stabilizing effect with a long relaxation time and a destabilizing effect with a short relaxation time. These conditions are precisely the same as those that give rise to overstability. This might explain why overstability and inverted bifurcation occur in the same systems

Minimal lepton flavor violating realizations of minimal seesaw models

We study the implications of the global U(1)R symmetry present in minimal lepton flavor violating implementations of the seesaw mechanism for neutrino masses. In the context of minimal type I seesaw scenarios with a slightly broken U(1)R, we show that, depending on the R-charge assignments, two classes of generic models can be identified. Models where the right-handed neutrino masses and the lepton number breaking scale are decoupled, and models where the parameters that slightly break the U(1)R induce a suppression in the light neutrino mass matrix. We show that within the first class of models, contributions of right-handed neutrinos to charged lepton flavor violating processes are severely suppressed. Within the second class of models we study the charged lepton flavor violating phenomenology in detail, focusing on mu to e gamma, mu to 3e and mu to e conversion in nuclei. We show that sizable contributions to these processes are naturally obtained for right-handed neutrino masses at the TeV scale. We then discuss the interplay with the effects of the right-handed neutrino interactions on primordial B - L asymmetries, finding that sizable right-handed neutrino contributions to charged lepton flavor violating processes are incompatible with the requirement of generating (or even preserving preexisting) B - L asymmetries consistent with the observed baryon asymmetry of the Universe.Comment: 21 pages, 4 figures; version 2: Discussion on possible generic models extended, typos corrected, references added. Version matches publication in JHE

Fundamental Strings, Holography, and Nonlinear Superconformal Algebras

We discuss aspects of holography in the AdS_3 \times S^p near string geometry of a collection of straight fundamental heterotic strings. We use anomalies and symmetries to determine general features of the dual CFT. The symmetries suggest the appearance of nonlinear superconformal algebras, and we show how these arise in the framework of holographic renormalization methods. The nonlinear algebras imply intricate formulas for the central charge, and we show that in the bulk these correspond to an infinite series of quantum gravity corrections. We also makes some comments on the worldsheet sigma-model for strings on AdS_3\times S^2, which is the holographic dual geometry of parallel heterotic strings in five dimensions.Comment: 25 page

Radiative contribution to neutrino masses and mixing in μν\mu\nuSSM

In an extension of the minimal supersymmetric standard model (popularly known as the $\mu\nu$SSM), three right handed neutrino superfields are introduced to solve the $\mu$-problem and to accommodate the non-vanishing neutrino masses and mixing. Neutrino masses at the tree level are generated through $R-$parity violation and seesaw mechanism. We have analyzed the full effect of one-loop contributions to the neutrino mass matrix. We show that the current three flavour global neutrino data can be accommodated in the $\mu\nu$SSM, for both the tree level and one-loop corrected analyses. We find that it is relatively easier to accommodate the normal hierarchical mass pattern compared to the inverted hierarchical or quasi-degenerate case, when one-loop corrections are included.Comment: 51 pages, 14 figures (58 .eps files), expanded introduction, other minor changes, references adde

Decoupling property of the supersymmetric Higgs sector with four doublets

In supersymmetric standard models with multi Higgs doublet fields, selfcoupling constants in the Higgs potential come only from the D-terms at the tree level. We investigate the decoupling property of additional two heavier Higgs doublet fields in the supersymmetric standard model with four Higgs doublets. In particular, we study how they can modify the predictions on the quantities well predicted in the minimal supersymmetric standard model (MSSM), when the extra doublet fields are rather heavy to be measured at collider experiments. The B-term mixing between these extra heavy Higgs bosons and the relatively light MSSM-like Higgs bosons can significantly change the predictions in the MSSM such as on the masses of MSSM-like Higgs bosons as well as the mixing angle for the two light CP-even scalar states. We first give formulae for deviations in the observables of the MSSM in the decoupling region for the extra two doublet fields. We then examine possible deviations in the Higgs sector numerically, and discuss their phenomenological implications.Comment: 26 pages, 24 figures, text sligtly modified,version to appear in Journal of High Energy Physic

Angular and Current-Target Correlations in Deep Inelastic Scattering at HERA

Correlations between charged particles in deep inelastic ep scattering have been studied in the Breit frame with the ZEUS detector at HERA using an integrated luminosity of 6.4 pb-1. Short-range correlations are analysed in terms of the angular separation between current-region particles within a cone centred around the virtual photon axis. Long-range correlations between the current and target regions have also been measured. The data support predictions for the scaling behaviour of the angular correlations at high Q2 and for anti-correlations between the current and target regions over a large range in Q2 and in the Bjorken scaling variable x. Analytic QCD calculations and Monte Carlo models correctly describe the trends of the data at high Q2, but show quantitative discrepancies. The data show differences between the correlations in deep inelastic scattering and e+e- annihilation.Comment: 26 pages including 10 figures (submitted to Eur. J. Phys. C

A review of elliptical and disc galaxy structure, and modern scaling laws

A century ago, in 1911 and 1913, Plummer and then Reynolds introduced their models to describe the radial distribution of stars in `nebulae'. This article reviews the progress since then, providing both an historical perspective and a contemporary review of the stellar structure of bulges, discs and elliptical galaxies. The quantification of galaxy nuclei, such as central mass deficits and excess nuclear light, plus the structure of dark matter halos and cD galaxy envelopes, are discussed. Issues pertaining to spiral galaxies including dust, bulge-to-disc ratios, bulgeless galaxies, bars and the identification of pseudobulges are also reviewed. An array of modern scaling relations involving sizes, luminosities, surface brightnesses and stellar concentrations are presented, many of which are shown to be curved. These 'redshift zero' relations not only quantify the behavior and nature of galaxies in the Universe today, but are the modern benchmark for evolutionary studies of galaxies, whether based on observations, N-body-simulations or semi-analytical modelling. For example, it is shown that some of the recently discovered compact elliptical galaxies at 1.5 < z < 2.5 may be the bulges of modern disc galaxies.Comment: Condensed version (due to Contract) of an invited review article to appear in "Planets, Stars and Stellar Systems"(www.springer.com/astronomy/book/978-90-481-8818-5). 500+ references incl. many somewhat forgotten, pioneer papers. Original submission to Springer: 07-June-201

Pharmacokinetic-Pharmacodynamic Modeling in Pediatric Drug Development, and the Importance of Standardized Scaling of Clearance.

Pharmacokinetic/pharmacodynamic (PKPD) modeling is important in the design and conduct of clinical pharmacology research in children. During drug development, PKPD modeling and simulation should underpin rational trial design and facilitate extrapolation to investigate efficacy and safety. The application of PKPD modeling to optimize dosing recommendations and therapeutic drug monitoring is also increasing, and PKPD model-based dose individualization will become a core feature of personalized medicine. Following extensive progress on pediatric PK modeling, a greater emphasis now needs to be placed on PD modeling to understand age-related changes in drug effects. This paper discusses the principles of PKPD modeling in the context of pediatric drug development, summarizing how important PK parameters, such as clearance (CL), are scaled with size and age, and highlights a standardized method for CL scaling in children. One standard scaling method would facilitate comparison of PK parameters across multiple studies, thus increasing the utility of existing PK models and facilitating optimal design of new studies

Sandstone matrix acidizing knowledge and future development

To meet rising global demands for energy, the oil and gas industry continuously strives to develop innovative oilfield technologies. With the development of new enhanced oil recovery techniques, sandstone acidizing has been significantly developed to contribute to the petroleum industry. Different acid combinations have been applied to the formation, which result in minimizing the near wellbore damage and improving the well productivity. A combination of hydrofluoric acid and hydrochloric acid (HF:HCl) known as mud acid has gained attractiveness in improving the porosity and permeability of the reservoir formation. However, high-temperature matrix acidizing is now growing since most of the wells nowadays become deeper and hotter temperature reservoirs, with a temperature higher than 200 °F. As a result, mud acid becomes corrosive, forms precipitates and reacts rapidly, which causes early consumption of acid, hence becoming less efficient due to high pH value. However, different acids have been developed to combat these problems where studies on retarded mud acids, organic-HF acids, emulsified acids, chelating agents have shown their effectiveness at different conditions. These acids proved to be alternative to mud acid in sandstone acidizing, but the reaction mechanism and experimental analysis have not yet been investigated. The paper critically reviews the sandstone acidizing mechanism with different acids, problems occurred during the application of different acids and explores the reasons when matrix stimulation is successful over fracturing. This paper also explores the future developing requirement for matrix acidizing treatments and new experimental techniques that can be useful for further development, particularly in developing new acids and acidizing techniques, which would provide better results and information of topology, morphology and mineral dissolution and the challenges associated with implementing these “new” technologies

A numerical modelling and simulation of core-scale sandstone acidizing process: a study on the effect of temperature

A wide and comprehensive understanding of the chemical reactions and mechanisms of HBF4 is crucial as it significantly influences its performance in stimulating a sandstone formation. In general, it is well-known that HBF4 is able to provide a deeper penetration into the sandstone matrix before being spent due to its uniquely slow hydrolysis ability to produce HF. In the present study, a 3D numerical modelling and simulation were conducted to examine the capability of HBF4 in enhancing the porosity and permeability of the sandstone matrix. The model is built in COMSOL® Multiphysics commercial software of computational fluid dynamics (CFD) to simulate the acid core flooding process on sandstone core. The model had been validated against the experimental data in the literature. The results matched with the measured plot data very well. The effect of temperature on the performance HBF4 sandstone acidizing is evaluated in this study. The simulation results indicated that at low temperature of 25 °C, HBF4 is not very effective, as justified in its poor porosity and permeability increments of only 1.07 and 1.23, respectively. However, at elevated temperatures, the porosity and permeability enhancement also become increasingly more significant, which showed 1.26 and 2.06, respectively, at 65 °C; and 1.67 and 7.06, respectively, at 105 °C. Therefore, one can conclude that HBF4 acid treatment performed better at elevated temperatures due to increased hydrolysis rate, which is a governing function in HBF4 sandstone acidizing. Overall, this model had provided a reliable alternative to optimize various other parameters of HBF4 acid treatment