Comments on the Fate of unstable orbifolds

We study the localized tachyon condensation in their mirror Landau-Ginzburg picture. We completely determine the decay mode of an unstable orbifold $C^r/Z_n$, $r=1,2,3$ under the condensation of a tachyon with definite R-charge and mass by extending the Vafa's work hep-th/0111105. Here, we give a simple method that works uniformly for all $C^r/Z_n$. For $C^2/Z_n$, where method of toric geometry works, we give a proof of equivalence of our method with toric one. For $C^r/Z_n$ cases, the orbifolds decay into sum of $r$ far separated orbifolds.Comment: 14 page, 2 figure

Localized tachyon mass and a g-theorem analogue

We study the localized tachyon condensation (LTC) of non-supersymmetric orbifold backgrounds in their mirror Landau-Ginzburg picture. Using he existence of four copies of (2,2) worldsheet supersymmetry, we show at the CFT level, that the minimal tachyon mass in twisted sectors shows somewhat analogous properties of c- or g-function. Namely, $m := |\alpha' M^2_{min}|$ satisfies $m(M) \geq m(D_1\oplus D_2)={\rm max} \{m(D_1),m(D_2)\}$. $c$- $g$- $m$- functions share the common property $f(M)\geq f(D_1\oplus D_2)$ for $f=c,g,m$, although they have different behavior in detail.Comment: 15 pages, no figure, to appear in NP

Superconductivity from D3/D7: Holographic Pion Superfluid

We show that a D3/D7 system (at zero quark mass limit) at finite isospin chemical potential goes through a superconductor (superfluid) like phase transition. This is similar to a flavored superfluid phase studied in QCD literature, where mesonic operators condensate. We have studied the frequency dependent conductivity of the condensate and found a delta function pole in the zero frequency limit. This is an example of superconductivity in a string theory context. Consequently we have found a superfluid/supercurrent type solution and studied the associated phase diagram. The superconducting transition changes from second order to first order at a critical superfluid velocity. We have studied various properties of the superconducting system like superfluid density, energy gap, second sound etc. We investigate the possibility of the isospin chemical potential modifying the embedding of the flavor branes by checking whether the transverse scalars also condense at low temperature. This however does not seem to be the case.Comment: 18 pages, 8 figures, revtex

Minimal seesaw model with tri/bi-maximal mixing and leptogenesis

We examine minimal seesaw mechanism in which the masses of light neutrinos are described with tri/bi-maximal mixing in the basis where the charged-lepton Yukawa matrix and heavy Majorana neutrino mass matrix are diagonal. We search for all possible Dirac mass textures which contain at least one zero entry in $3 \times 2$ matrix and evaluate the corresponding lepton asymmetries. We present the baryon asymmetry in terms of a single low energy unknown, a Majorana CP phase to be clued from neutrinoless double beta decay.Comment: 10 pages, 4 figures, revtex4, version to appear in Phys. Lett.

Non-Abelian Discrete Flavor Symmetries on Orbifolds

We study non-Abelian flavor symmetries on orbifolds, $S^1/Z_2$ and $T^2/Z_3$. Our extra dimensional models realize $D_N$, $\Sigma(2N^2)$, $\Delta(3N^2)$ and $\Delta(6N^2)$ including $A_4$ and $S_4$. In addition, one can also realize their subgroups such as $Q_N$, $T_7$, etc. The $S_3$ flavor symmetry can be realized on both $S^1/Z_2$ and $T^2/Z_3$ orbifolds.Comment: 16 page

Cardiac hypertrophy is inhibited by a local pool of cAMP regulated by phosphodiesterase 2

Rationale: Chronic elevation of 3'-5'-cyclic adenosine monophosphate (cAMP) levels has been associated with cardiac remodelling and cardiac hypertrophy. However, enhancement of particular aspects of cAMP/protein kinase A (PKA) signalling appears to be beneficial for the failing heart. cAMP is a pleiotropic second messenger with the ability to generate multiple functional outcomes in response to different extracellular stimuli with strict fidelity, a feature that relies on the spatial segregation of the cAMP pathway components in signalling microdomains. Objective: How individual cAMP microdomains impact on cardiac pathophysiology remains largely to be established. The cAMP-degrading enzymes phosphodiesterases (PDEs) play a key role in shaping local changes in cAMP. Here we investigated the effect of specific inhibition of selected PDEs on cardiac myocyte hypertrophic growth. Methods and Results: Using pharmacological and genetic manipulation of PDE activity we found that the rise in cAMP resulting from inhibition of PDE3 and PDE4 induces hypertrophy whereas increasing cAMP levels via PDE2 inhibition is anti-hypertrophic. By real-time imaging of cAMP levels in intact myocytes and selective displacement of PKA isoforms we demonstrate that the anti-hypertrophic effect of PDE2 inhibition involves the generation of a local pool of cAMP and activation of a PKA type II subset leading to phosphorylation of the nuclear factor of activated T cells (NFAT). Conclusions: Different cAMP pools have opposing effects on cardiac myocyte cell size. PDE2 emerges as a novel key regulator of cardiac hypertrophy in vitro and in vivo and its inhibition may have therapeutic applications

Geographical trends in academic conferences: An analysis of authors’ affiliations

In the last decade, the research literature has reached an enormous volume with an unprecedented current annual increase of 1.5 million new publications. As research gets ever more global and new countries and institutions, either from academia or corporate environments, start to contribute, it is important to monitor this complex phenomenon and understand its dynamics and equilibria. We present a study on a conference proceedings dataset extracted from Springer Nature SciGraph that illustrates insightful geographical trends and highlights the unbalanced growth of competitive research institutions worldwide in the 1996–2016 period. The main contribution of this work is fourfold. In the first instance, we found that the distributions of institutions and publications among countries follow a power law, consistently with previous literature, i.e., very few countries keep producing most of the papers accepted by high-tier conferences. Secondly, we show how the turnover rate of country rankings is extremely low and steadily declines over time, suggesting an alarmingly static landscape in which new entries struggle to emerge. We also performed an analysis of the venue locations and their effect on the distribution of countries involved in the publications, underlining the central role of Europe and China as knowledge hubs. Finally, we evidence the presence of an increasing gap between the number of institutions initiating and overseeing research endeavours (i.e. first and last authors’ affiliations) and the total number of institutions participating in research. The paper also discusses our experience in working with authors’ affiliations: an utterly simple matter at first glance, that is instead revealed to be a complex research and technical challenge

Weak Mixing Angle and Higgs Mass in Gauge-Higgs Unification Models with Brane Kinetic Terms

We show that the idea of Gauge-Higgs unification(GHU) can be rescued from the constraint of weak mixing angle by introducing localized brane kinetic terms in higher dimensional GHU models with bulk and simple gauge groups. We find that those terms lead to a ratio between Higgs and W boson masses, which is a little bit deviated from the one derived in the standard model. From numerical analysis, we find that the current lower bound on the Higgs mass tends to prefer to exceptional groups E(6), E(7), E(8) rather than other groups like SU(3l), SO(2n+1), G(2), and F(4) in 6-dimensional(D) GHU models irrespective of the compactification scales. For the compactification scale below 1 TeV, the Higgs masses in 6D GHU models with SU(3l), SO(2n+1), G(2), and F(4) groups are predicted to be less than the current lower bound unless a model parameter responsible for re-scaling SU(2) gauge coupling is taken to be unnaturally large enough. To see how the situation is changed in more higher dimensional GHU model, we take 7D S^{3}/ Z_{2} and 8D T^{4}/ Z_{2} models. It turns out from our numerical analysis that these higher dimensional GHU models with gauge groups except for E(6) can lead to the Higgs boson whose masses are predicted to be above the current lower bound only for the compatification scale above 1 TeV without taking unnaturally large value of the model parameter, whereas the Higgs masses in the GHU models with E(6) are compatible with the current lower bound even for the compatification scale below 1 TeV.Comment: 22 pages, 4 figure

Constraining parameter space in type-II two-Higgs doublet model in light of a 126 GeV Higgs boson

We explore the implications of a 126 GeV Higgs boson indicated by the recent LHC results for two-Higgs doublet model (2HDM). Identifying the 126 GeV Higgs boson as either the lighter or heavier of CP even neutral Higgs bosons in 2HDM, we examine how the masses of Higgs fields and mixing parameters can be constrained by the theoretical conditions and experimental constraints. The theoretical conditions taken into account are the vacuum stability, perturbativity and unitarity required to be satisfied up to a cut-off scale. We also show how bounds on the masses of Higgs bosons and mixing parameters depend on the cut-off scale. In addition, we investigate whether the allowed regions of parameter space can accommodate particularly the enhanced di-photon signals, ZZ* and WW* decay modes of the Higgs boson, and examine the prediction of the signal strength of Z{\gamma} decay mode for the allowed regions of the parameter space.Comment: To be published in JHEP, 20 pages, 11 figures, Figures and results are updated for the recent LHC result

Where to draw the line? Using movement data to inform protected area design and conserve mobile species

Protected areas (PAs) are a cornerstone of modern conservation. For PAs that are established to conserve mobile species, it is important to cover all the key areas regularly used by these species. However, zonation and boundaries of PAs have often been established with limited knowledge of animal movements, leaving the effectiveness of some PAs doubtful. We used radio tracking data to evaluate the extent to which two coastal PAs in mainland China encompassed the full range of habitats used by migratory shorebirds during non-breeding seasons. The core zone (highest restriction on human activities) of the Yalu Jiang Estuary National Nature Reserve (Liaoning) incorporated only 22 ± 6% (n = 34) of the diurnal home range (95% kernel density) of the endangered great knots Calidris tenuirostris. In contrast, the core zone of Chongming Dongtan (Shanghai) incorporated 73 ± 24% (n = 25) of the home range of dunlins Calidris alpina. During high tide, great knots in Yalu Jiang mostly occurred in the experimental zone (least restriction on human activities) or sometimes outside the PA boundary altogether, where the birds could face substantial threats. By investigating satellite tracking records, consulting published literature, interviewing local experts and mapping habitat composition in different coastal PAs in China, we found that wet artificial supratidal habitats were frequently used by migratory shorebirds but the coverage of these habitats in coastal PAs was low. These PA boundaries and/or zonations should be revised to conserve mobile species more effectively. With the increasing number of tracking studies, analysing the spatial relationships between PAs and the movement ranges of mobile species can increasingly inform the development of a representative, comprehensive PA network