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We examine the proposal in the previous paper to resolve the puzzle in transitions in discrete gauge groups. We focus on a four-section geometry to test the proposal. We observed that a discrete ℤ2 gauge group enlarges and U(1) also forms in F-theory along any bisection geometries locus in the four-section geometry built as the complete intersections of two quadrics in ℙ3 fibered over any base. Furthermore, we demonstrate that giving vacuum expectation values to hypermultiplets breaks the enlarged U(1) × ℤ2 gauge group down to a discrete ℤ4 gauge group via Higgsing. We thus confirmed that the proposal in the previous paper is consistent when a four-section splits into a pair of bisections in the four-section geometry. This analysis may be useful for understanding the Higgsing processes occurring in the transitions in discrete gauge groups in six-dimensional F-theory models. We also discuss the construction of a family of six-dimensional F-theory models in which U(1) × ℤ4 forms. [ABSTRACT FROM AUTHOR]

In this study, we introduce a new class of rational elliptic 3-folds, which we refer to as “1/2 Calabi-Yau 3-folds”. We construct elliptically fibered Calabi-Yau 3-folds by utilizing these rational elliptic 3-folds. The construction yields a novel approach to build elliptically fibered Calabi-Yau 3-folds of various Mordell-Weil ranks. Our construction of Calabi-Yau 3-folds can be considered as a three-dimensional generalization of the operation of gluing pairs of 1/2 K3 surfaces to yield elliptic K3 surfaces. From one to seven U(1)s form in six-dimensional N = 1 F-theory on the constructed Calabi-Yau 3-folds. Seven tensor multiplets arise in these models. [ABSTRACT FROM AUTHOR]

We argue that global F-theory compactifications to four dimensions gener- ally exhibit higher rank Yukawa matrices from multiple geometric contributions known as Yukawa points. The holomorphic couplings furthermore have large hierarchies for generic complex structure moduli. Unlike local considerations, the compact setup realizes these features all through geometry, and requires no instanton corrections. As an example, we consider a concrete toy model with SU(5) × U(1) gauge symmetry. From the geometry, we find two Yukawa points for the 1 0 − 2 5 ¯ 6 5 ¯ − 4 coupling, producing a rank two Yukawa matrix. Our methods allow us to track all complex structure dependencies of the holomorphic couplings and study the ratio numerically. This reveals hierarchies of O (105) and larger on a full-dimensional subspace of the moduli space. [ABSTRACT FROM AUTHOR]

We apply machine learning techniques to solve a specific classification problem in 4D F-theory. For a divisor D on a given complex threefold base, we want to read out the non-Higgsable gauge group on it using local geometric information near D. The input features are the triple intersection numbers among divisors near D and the output label is the non-Higgsable gauge group. We use decision tree to solve this problem and achieved 85%-98% out-of-sample accuracies for different classes of divisors, where the data sets are generated from toric threefold bases without (4,6) curves. We have explicitly generated a large number of analytic rules directly from the decision tree and proved a small number of them. As a crosscheck, we applied these decision trees on bases with (4,6) curves as well and achieved high accuracies. Additionally, we have trained a decision tree to distinguish toric (4,6) curves as well. Finally, we present an application of these analytic rules to construct local base configurations with interesting gauge groups such as SU(3). [ABSTRACT FROM AUTHOR]

Using a one-way Monte Carlo algorithm from several different starting points, we get an approximation to the distribution of toric threefold bases that can be used in four-dimensional F-theory compactification. We separate the threefold bases into 'resolvable' ones where the Weierstrass polynomials ( f, g) can vanish to order (4 , 6) or higher on codimension-two loci and the 'good' bases where these (4 , 6) loci are not allowed. A simple estimate suggests that the number of distinct resolvable base geometries exceeds 10, with over 10 'good' bases, though the actual numbers are likely much larger. We find that the good bases are concentrated at specific 'end points' with special isolated values of h that are bigger than 1,000. These end point bases give Calabi-Yau fourfolds with specific Hodge numbers mirror to elliptic fibrations over simple threefolds. The non-Higgsable gauge groups on the end point bases are almost entirely made of products of E, F, G and SU(2). Nonetheless, we find a large class of good bases with a single non-Higgsable SU(3). Moreover, by randomly contracting the end point bases, we find many resolvable bases with h( B) ∼ 50-200 that cannot be contracted to another smooth threefold base. [ABSTRACT FROM AUTHOR]

We show that F-theory compactifications with abelian gauge factors generally exhibit a non-trivial global gauge group structure. The geometric origin of this structure lies with the Shioda map of the Mordell-Weil generators. This results in constraints on the $$ \mathfrak{u}(1) $$ charges of non-abelian matter consistent with observations made throughout the literature. In particular, we find that F-theory models featuring the Standard Model algebra actually realise the precise gauge group [SU(3) × SU(2) × U(1)]/ ℤ . Furthermore, we explore the relationship between the gauge group structure and geometric (un-)higgsing. In an explicit class of models, we show that, depending on the global group structure, an $$ \mathfrak{s}\mathfrak{u}(2)\oplus \mathfrak{u}(1) $$ gauge theory can either unhiggs into an SU(2) × SU(2) or an SU(3) × SU(2) theory. We also study implications of the charge constraints as a criterion for the F-theory 'swampland'. [ABSTRACT FROM AUTHOR]

Supergravity theories in more than four dimensions with grand unified gauge symmetries are an important intermediate step towards the ultraviolet completion of the Standard Model in string theory. Using toric geometry, we classify and analyze six-dimensional F-theory vacua with gauge group SO(10) taking into account Mordell-Weil U(1) and discrete gauge factors. We determine the full matter spectrum of these models, including charged and neutral SO(10) singlets. Based solely on the geometry, we compute all matter multiplicities and confirm the cancellation of gauge and gravitational anomalies independent of the base space. Particular emphasis is put on symmetry enhancements at the loci of matter fields and to the frequent appearance of superconformal points. They are linked to non-toric Kähler deformations which contribute to the counting of degrees of freedom. We compute the anomaly coefficients for these theories as well by using a base-independent blow-up procedure and superconformal matter transitions. Finally, we identify six-dimensional supergravity models which can yield the Standard Model with high-scale supersymmetry by further compactification to four dimensions in an Abelian flux background. [ABSTRACT FROM AUTHOR]

Using E-strings, we can analyze not only six-dimensional superconformal field theories but also probe vacua of non-perturabative heterotic string. We study strings made of D3-branes wrapped on various two-cycles in the global F-theory setup. We claim that E-strings are elementary in the sense that various combinations of E-strings can form M-strings as well as heterotic strings and new kind of strings, called G-strings. Using them, we show that emissions and combinations of heterotic small instantons generate most of known six-dimensional superconformal theories, their affinizations and little string theories. Taking account of global structure of compact internal geometry, we also show that special combinations of E-strings play an important role in constructing six-dimensional theories of D- and E-types. We check global consistency conditions from anomaly cancellation conditions, both from five-branes and strings, and show that they are given in terms of elementary E-string combinations. [ABSTRACT FROM AUTHOR]

According to a recent classification of 6d (1 , 0) theories within F-theory there are only six 'pure' 6d gauge theories which have a UV superconformal fixed point. The corresponding gauge groups are SU(3) , SO(8) , F , E , E , and E . These exceptional models have BPS strings which are also instantons for the corresponding gauge groups. For G simply-laced, we determine the 2d $$ \mathcal{N}=\left(0,4\right) $$ worldsheet theories of such BPS instanton strings by a simple geometric engineering argument. These are given by a twisted S compactification of the 4d $$ \mathcal{N}=2 $$ theories of type H , D , E , E and E (and their higher rank generalizations), where the 6d instanton number is mapped to the rank of the corresponding 4d SCFT. This determines their anomaly polynomials and, via topological strings, establishes an interesting relation among the corresponding T × S partition functions and the Hilbert series for moduli spaces of G instantons. Such relations allow to bootstrap the corresponding elliptic genera by modularity. As an example of such procedure, the elliptic genera for a single instanton string are determined. The same method also fixes the elliptic genus for case of one F instanton. These results unveil a rather surprising relation with the Schur index of the corresponding 4d $$ \mathcal{N}=2 $$ models. [ABSTRACT FROM AUTHOR]

Starting from 6D superconformal field theories (SCFTs) realized via F-theory, we show how reduction on a circle leads to a uniform perspective on the phase structure of the resulting 5D theories, and their possible conformal fixed points. Using the correspon-dence between F-theory reduced on a circle and M-theory on the corresponding elliptically fibered Calabi-Yau threefold, we show that each 6D SCFT with minimal supersymmetry directly reduces to a collection of between one and four 5D SCFTs. Additionally, we find that in most cases, reduction of the tensor branch of a 6D SCFT yields a 5D generalization of a quiver gauge theory. These two reductions of the theory often correspond to different phases in the 5D theory which are in general connected by a sequence of flop transitions in the extended Kähler cone of the Calabi-Yau threefold. We also elaborate on the structure of the resulting conformal fixed points, and emergent flavor symmetries, as realized by M-theory on a canonical singularity. [ABSTRACT FROM AUTHOR]

We determine the discrete gauge symmetries that arise in F-theory compactifications on examples of genus-one fibered Calabi-Yau 4-folds without a section. We construct genus-one fibered Calabi-Yau 4-folds using Fano manifolds, cyclic 3-fold covers of Fano 4-folds, and Segre embeddings of products of projective spaces. Discrete ℤ , ℤ , ℤ and ℤ symmetries arise in these constructions. We introduce a general method to obtain multisections for several constructions of genus-one fibered Calabi-Yau manifolds. The pullbacks of hyperplane classes under certain projections represent multisections to these genus-one fibrations. We determine the degrees of these multisections by computing the intersection numbers with fiber classes. As a result, we deduce the discrete gauge symmetries that arise in F-theory compactifications. This method applies to various Calabi-Yau genus-one fibrations. [ABSTRACT FROM AUTHOR]

Warped higher-dimensional compactifications with "bulk" standard model, or their AdS/CFT dual as the purely 4D scenario of Higgs compositeness and partial compositeness, offer an elegant approach to resolving the electroweak hierarchy problem as well as the origins of avor structure. However, low-energy electroweak/avor/CP constraints and the absence of non-standard physics at LHC Run 1 suggest that a "little hierarchy problem" remains, and that the new physics underlying naturalness may lie out of LHC reach. Assuming this to be the case, we show that there is a simple and natural extension of the minimal warped model in the Randall-Sundrum framework, in which matter, gauge and gravitational fields propagate modestly different degrees into the IR of the warped dimension, resulting in rich and striking consequences for the LHC (and beyond). The LHC-accessible part of the new physics is AdS/CFT dual to the mechanism of "vectorlike confinement", with TeV-scale Kaluza-Klein excitations of the gauge and gravitational fields dual to spin-0,1,2 composites. Unlike the minimal warped model, these low-lying excitations have predominantly avor-blind and avor/CP-safe interactions with the standard model. Remarkably, this scenario also predicts small deviations from avor-blindness originating from virtual effects of Higgs/top compositeness at ~ O(10) TeV, with subdominant resonance decays into Higgs/top-rich final states, giving the LHC an early "preview" of the nature of the resolution of the hierarchy problem. Discoveries of this type at LHC Run 2 would thereby anticipate (and set a target for) even more explicit explorations of Higgs compositeness at a 100TeV collider, or for next-generation avor tests. [ABSTRACT FROM AUTHOR]

We systematically analyze the local combinations of gauge groups and matter that can arise in 6D F-theory models over a fixed base. We compare the low-energy constraints of anomaly cancellation to explicit F-theory constructions using Weierstrass and Tate forms, and identify some new local structures in the 'swampland' of 6D supergravity and SCFT models that appear consistent from low-energy considerations but do not have known F-theory realizations. In particular, we classify and carry out a local analysis of all enhancements of the irreducible gauge and matter contributions from 'non-Higgsable clusters,' and on isolated curves and pairs of intersecting rational curves of arbitrary self-intersection. Such enhancements correspond physically to unHiggsings, and mathematically to tunings of the Weierstrass model of an elliptic CY threefold. We determine the shift in Hodge numbers of the elliptic threefold associated with each enhancement. We also consider local tunings on curves that have higher genus or intersect multiple other curves, codimension two tunings that give transitions in the F-theory matter content, tunings of abelian factors in the gauge group, and generalizations of the ' E8' rule to include tunings and curves of self-intersection zero. These tools can be combined into an algorithm that in principle enables a finite and systematic classification of all elliptic CY threefolds and corresponding 6D F-theory SUGRA models over a given compact base (modulo some technical caveats in various special circumstances), and are also relevant to the classification of 6D SCFT's. To illustrate the utility of these results, we identify some large example classes of known CY threefolds in the Kreuzer-Skarke database as Weierstrass models over complex surface bases with specific simple tunings, and we survey the range of tunings possible over one specific base. [ABSTRACT FROM AUTHOR]

We study global symmetry groups of six-dimensional superconformal field theories (SCFTs). In the Coulomb branch we use field theoretical arguments to predict an upper bound for the global symmetry of the SCFT. We then analyze global symmetry groups of F-theory constructions of SCFTs with a one-dimensional Coulomb branch. While in the vast majority of cases, all of the global symmetries allowed by our Coulomb branch analysis can be realized in F-theory, in a handful of cases we find that F-theory models fail to realize the full symmetry of the theory on the Coulomb branch. In one particularly mysterious case, F-theory models realize several distinct maximal subgroups of the predicted group, but not the predicted group itself. [ABSTRACT FROM AUTHOR]

We review some recent developments regarding supersymmetric field theories in six and five dimensions. In particular, we will describe the classification of supersymmetric six-dimensional theories with a holographic IIA dual; they are 'linear quivers' consisting of chains of many SU (or SO/Sp) gauge groups connected by hypermultiplets and tensor multiplets. We will also describe the wider classification of supersymmetric six-dimensional theories that can be engineered in F-theory; these are also chains, but they include exceptional gauge groups and copies of a more exotic 'E-string' theory with a single tensor and E8 flavor symmetry. Finally we discuss some properties of these theories under compactification to lower dimensions. [ABSTRACT FROM AUTHOR]

Genetically modified (GM) plants expressing Bt toxin provide protection against lepidopteran pests. The only GM crop in Pakistan is Bt cotton, which was illegally imported and adopted rapidly by cotton producers. Farmers gained access to the seed of many unapproved Bt genotypes before the matter was picked up and formal approval granted by the relevant governmental agencies. The present study was conducted to evaluate the samples of Bt cotton, collected from farmers and seed dealer, for transgene integration and expression. Seeds of 52 cotton genotypes, labelled as Bt, were collected from various farmers and seed dealers. An immunoblot strip test was carried out, which showed that only 0·86 of the samples collected were synthesizing Cry1Ac toxin. According to multiplexed polymerase chain reaction (PCR) results, 0·86 of the genotypes tested were positive for the Mon531 event (an ‘event’ is a specific genetic modification in a specific species) and 0·14 were negative for any transgene. Transcript analysis of transgenes in positive genotypes by real-time Rt-PCR confirmed the synthesis of mRNA in all genotypes but with significant variation. The concentration of Bt toxin revealed by enzyme linked immunosorbent assay (ELISA) showed that only 0·02 genotypes had the reported optimum level. The real-time PCR and ELISA results further confirmed the attenuation of transgene expression at transcriptional and translational level by various internal and external factors. The same type of event was found in all genotypes, with significant variation in toxin level, revealing the impact of genetic background on transgene expression. The findings support the recommendation to improve the existing quality criteria for transgenic cotton variety approval and certification in Pakistan, with the inclusion of toxin concentration in the list of parameters to be considered. [ABSTRACT FROM PUBLISHER]

Heavy metals, which have widespread environmental distribution and originate from natural and anthropogenic sources, are common environmental pollutants. In recent decades, their contamination has increased dramatically because of continuous discharge in sewage and untreated industrial effluents. Because they are non-degradable, they persist in the environment; accordingly, they have received a great deal of attention owing to their potential health and environmental risks. Although the toxic effects of metals depend on the forms and routes of exposure, interruptions of intracellular homeostasis include damage to lipids, proteins, enzymes and DNA via the production of free radicals. Following exposure to heavy metals, their metabolism and subsequent excretion from the body depends on the presence of antioxidants (glutathione, α-tocopherol, ascorbate, etc.) associated with the quenching of free radicals by suspending the activity of enzymes (catalase, peroxidase, and superoxide dismutase). Therefore, this review was written to provide a deep understanding of the mechanisms involved in eliciting their toxicity in order to highlight the necessity for development of strategies to decrease exposure to these metals, as well as to identify substances that contribute significantly to overcome their hazardous effects within the body of living organisms. [ABSTRACT FROM AUTHOR]

We use F-theory to classify possibly all six-dimensional superconformal field theories (SCFTs). This involves a two step process: We first classify all possible tensor branches allowed in F-theory (which correspond to allowed collections of contractible spheres) and then classify all possible configurations of seven-branes wrapped over them. We describe the first step in terms of 'atoms' joined into 'radicals' and 'molecules,' using an analogy from chemistry. The second step has an interpretation via quiver-type gauge theories constrained by anomaly cancellation. A very surprising outcome of our analysis is that all of these tensor branches have the structure of a linear chain of intersecting spheres with a small amount of possible decoration at the two ends. The resulting structure of these SCFTs takes the form of a generalized quiver consisting of ADE-type nodes joined by conformal matter. A collection of highly non-trivial examples involving E8 small instantons probing an ADE singularity is shown to have an F-theory realization. This yields a classification of homomorphisms from ADE subgroups of [ABSTRACT FROM AUTHOR]

The first run of the LHC has been tremendously successful, having discovered the Higgs boson as well as having set stringent limits on superpartner masses. This has severely constrained supersymmetric models. A consistent scenario based on LHC data suggests that the third generation sfermions, Higgsinos and the gluino must be light while the first two generation sfermions are heavy. Furthermore, an extra contribution to the Higgs quartic coupling is needed to explain the 126 GeV Higgs mass. Interestingly this spectrum can naturally arise from supersymmetry breaking in a warped geometry where the sfermion spectrum is related to the fermion mass hierarchy. Various possible scenarios are reviewed and compared with the data from the first run at the LHC. [ABSTRACT FROM AUTHOR]

We analyze the standard model gauge group $$SU(3)\times SU(2) \times U(1)$$ constructed in F-theory. The non-Abelian part $$SU(3) \times SU(2)$$ is described by a surface singularity of Kodaira type. Blow-up analysis shows that the non-Abelian part is distinguished from the naïve product of $$SU(3)$$ and $$SU(2)$$ , but that it should be a rank three group along the chain of $$E_n$$ groups, because it has non-generic gauge symmetry enhancement structure responsible for desirable matter curves. The Abelian part $$U(1)$$ is constructed from a globally valid two-form with the desired gauge quantum numbers, using a similar method to the decomposition (factorization) method of the spectral cover. This technique makes use of an extra section in the elliptic fiber of the Calabi-Yau manifold, on which F-theory is compactified. Conventional gauge coupling unification of $$SU(5)$$ is achieved, without requiring a threshold correction from the flux along the hypercharge direction. [ABSTRACT FROM AUTHOR]

Four-form flux in F-theory compactifications not only stabilizes moduli, but gives rise to ensembles of string vacua, providing a scientific basis for a stringy notion of naturalness. Of particular interest in this context is the ability to keep track of algebraic information (such as the gauge group) associated with individual vacua while dealing with statistics. In the present work, we aim to clarify conceptual issues and sharpen methods for this purpose, using compactification on K3 × K3 as a test case. Our first approach exploits the connection between the stabilization of complex structure moduli and the Noether-Lefschetz problem. Compactification data for F-theory, however, involve not only a four-fold (with a given complex structure) Y and a flux on it, but also an elliptic fibration morphism Y→ B, which makes this problem complicated. The heterotic-F-theory duality indicates that elliptic fibration morphisms should be identified modulo isomorphism. Based on this principle, we explain how to count F-theory vacua on K3 × K3 while keeping the gauge group information. Mathematical results reviewed/developed in our companion paper are exploited heavily. With applications to more general four-folds in mind, we also clarify how to use Ashok-Denef-Douglas' theory of the distribution of flux vacua in order to deal with statistics of sub-ensembles tagged by a given set of algebraic/topological information. As a side remark, we extend the heterotic/F-theory duality dictionary on flux quanta and elaborate on its connection to the semistable degeneration of a K3 surface. [ABSTRACT FROM AUTHOR]

We develop geometric techniques to determine the spectrum and the chiral indices of matter multiplets for four-dimensional F-theory compactifications on elliptic Calabi-Yau fourfolds with rank two Mordell-Weil group. The general elliptic fiber is the Calabi-Yau onefold in dP. We classify its resolved elliptic fibrations over a general base B. The study of singularities of these fibrations leads to explicit matter representations, that we determine both for U(1) × U(1) and SU(5) × U(1) × U(1) constructions. We determine for the first time certain matter curves and surfaces using techniques involving prime ideals. The vertical cohomology ring of these fourfolds is calculated for both cases and general formulas for the Euler numbers are derived. Explicit calculations are presented for a specific base B = ℙ. We determine the general G-flux that belongs to $ H_V^{{\left( {2,2} \right)}} $ of the resolved Calabi-Yau fourfolds. As a by-product, we derive for the first time all conditions on G-flux in general F-theory compactifications with a non-holomorphic zero section. These conditions have to be formulated after a circle reduction in terms of Chern-Simons terms on the 3D Coulomb branch and invoke M-theory/F-theory duality. New Chern-Simons terms are generated by Kaluza-Klein states of the circle compactification. We explicitly perform the relevant field theory computations, that yield non-vanishing results precisely for fourfolds with a non-holomorphic zero section. Taking into account the new Chern-Simons terms, all 4D matter chiralities are determined via 3D M-theory/F-theory duality. We independently check these chiralities using the subset of matter surfaces we determined. The presented techniques are general and do not rely on toric data. [ABSTRACT FROM AUTHOR]

The backreactions of anti-branes on a variety of supergravity backgrounds have been shown in a recent series of papers to be riled by some unexplained flux singularities. All of the situations studied so far involve backgrounds with (close to) AdS-asymptotics. It is the purpose of this work to study the backreaction of anti-M2 branes on a background exhibiting a different UV behavior: the so-called $ \mathbb{A} $ regular solution of eleven-dimensional supergravity that we consider has 'Taub-NUT type' asymptotics. As it turns out, some subleading infrared singularities are inevitable; they cannot be naturally ascribed to the anti-branes backreacting on this background. Moreover, our configuration does not involve smeared branes. This lends further credence to the work of Bena et al. [33] suggesting that the singularities encountered are in no way remnants of smearing that would wash away once brane polarization is taken into account. [ABSTRACT FROM AUTHOR]

We analyze the spectra of non-chiral and chiral bifundamental mesons arising on intersecting D7-branes in AdS × S. In the absence of magnetic flux on the curve of intersection, the spectrum is non-chiral, and the dual gauge theory is conformal in the quenched/probe approximation. For this case we calculate the dimensions of the bifundamental mesonic operators. We then consider magnetization of the D7-branes, which deforms the dual theory by an irrelevant operator and renders the mesons chiral. The magnetic flux spoils the conformality of the dual theory, and induces a D3-brane charge that becomes large in the ultraviolet, where the non-normalizable bifundamental modes are rapidly divergent. An ultraviolet completion is therefore necessary to calculate the correlation functions in the chiral case. On the other hand, the normalizable modes are very well localized in the infrared, leading to new possibilities for local model-building on intersecting D7-branes in warped geometries. [ABSTRACT FROM AUTHOR]

Freshwater fish, Tor putitora caught from polluted portion of River Kabul was studied for various hepatic biochemical parameters and was compared with control fish caught from non polluted Warsak Dam to know the possible toxic effects of pollution in the river. Fish liver was dissected out and analyzed for various biochemical parameters like total protein, soluble protein, total cholesterol, total lipid, glucose, free amino acid, DNA, RNA and enzymes such as amylase, GOT, GPT and LDH. The hepatic total proteins, soluble proteins, total cholesterol, total lipids, glucose content and free amino acids in fish sample 1 and sample 2 increased 29% and 16%, 6% and 15%, 75% and 68%, 41% and 65%, 47% and 26%, and 333% and 729%, respectively as compared to control sample. The DNA content decreased 14% and 20%, whereas the RNA decreased 41% and 32% in sample 1 and 2, respectively. The fish sample from site I and II showed 5% and 17% increased hepatic amylase activity, 69% and 72% decreased GOT activity in sample 1 and 2, respectively. The GPT activity decreased 45% in sample 1 and increased 28% in sample 2. The LDH activity was decreased 69% in sample 1, but showed 14% increase in sample 2 as compared to control sample. The increase and decrease in various biochemical parameters and enzymes in the liver of test fish samples in comparison with the control shows the adverse effect of aquatic pollution on the fish health. Aquatic pollution could be one of the major reasons of rapid decline in population of this endangered South Asian fresh water fish. [ABSTRACT FROM AUTHOR]

F-theory models are constructed where the 7-brane has a nontrivial fundamental group. The base manifolds used are a toric Fano variety and a smooth toric threefold coming from a reflexive polyhedron. The discriminant locus of the elliptically fibered Calabi-Yau fourfold can be chosen such that one irreducible component is not simply connected (namely, an Enriques surface) and supports a non-Abelian gauge theory. [ABSTRACT FROM AUTHOR]

J. Neurochem. (2010) 114, 440–451. Previous in vitro and in vivo investigations have suggested manganese (Mn2+) may play a role in pathogenesis through facilitating refolding of the normal cellular form of the prion protein into protease resistant, pathogenic isoforms (PrPSc), as well as the subsequent promotion of higher order aggregation of these abnormal conformers. To further explore the role of Mn2+ in pathogenesis, we undertook a number of studies, including an assessment of the disease modifying effects of chelation therapy in a well-characterized mouse model of prion disease. The di-sodium, calcium derivative of the chelator, cyclohexanediaminetetraacetic acid (Na2CaCDTA), was administered intraperitoneally to mice inoculated intra-cerebrally with either high or low-dose inocula, with treatment beginning early (shortly after inoculation) or late (at the usual mid-survival point of untreated mice). Analyses by inductively coupled plasma-mass spectrometry demonstrated brain Mn2+ levels were selectively reduced by up to 50% in treated mice compared with untreated controls, with copper, iron, zinc and cobalt levels unchanged. In mice administered high-dose inocula, none of the treatment groups displayed an increase in survival although western blot analyses of early intensively treated mice showed reduced brain PrPSc levels; mice infected using low-dose inocula however, showed a significant prolongation of survival ( p = 0.002). Although our findings support a role for Mn2+ in prion disease, further studies are required to more precisely delineate the extent of pathogenic involvement. [ABSTRACT FROM AUTHOR]

We study the dynamics of a D3 brane in generic IIB warped compactifications, using the Hamiltonian formulation discussed in arXiv:0805.3700. Taking into account of both closed and open string fluctuations, we derive the warped Kähler potential governing the motion of a probe D3 brane. By including the backreaction of D3, we also comment on how the problem of defining a holomorphic gauge coupling on wrapped D7 branes in warped background can be resolved. [ABSTRACT FROM AUTHOR]

The article presents an overview of the political life of the Kashmiri Hindus, a community in the Muslim-majority region of Kashmir Valley in Jammu and Kashmir State in India. It highlights the development of Kashmiri Hindu collective identity in the country through community discourse in the 1990s. It also discusses the migration of the community to different towns and cities in the country while looking forward for an opportunity to return to their homeland.

We review the Batyrev approach to Calabi–Yau spaces based on reflexive weight vectors. The Universal CY algebra gives a possibility to construct the corresponding reflexive numbers in a recursive way. A physical interpretation of the Batyrev expression for the Calabi–Yau manifolds is presented. Important classes of these manifolds are related to the simple-laced and quasi-simple-laced numbers. We discuss the classification and recurrence relations for them in the framework of quantum field theory methods. A relation between the reflexive numbers and the so-called Berger graphs is studied. In this correspondence the role played by the generalized Coxeter labels is highlighted. Sets of positive roots are investigated in order to connect them to possible new algebraic structures stemming from the Berger matrices. [ABSTRACT FROM AUTHOR]

On promoting the type IIA side of the $\mathcal{N}=1$ heterotic/type IIA dual pairs of Ref. 1 to M-theory on a "barely G2 manifold" of Ref. 2, by spectrum-matching we show a possible triality between heterotic, M and F theories. The manifolds that figure in this triality are a self-mirror Calabi–Yau, a barely G2 manifold and an elliptically fibered Calabi–Yau four-fold with trivially rationally ruled CP1× Enriques surface base, respectively. We raise an apparent puzzle on the F-theory side, namely, the Hodge data of the 4-fold derived cannot be obtained by a naive freely acting orbifold of CY3(3,243)×T2 as one might have guessed on the basis of arguments related to dualities involving string, M and (definition of) F theories. There are some interesting properties of the antiholomorphic involution used in Ref. 1 for constructing the type IIA orientifold and by us in constructing the "barely G2 manifold," that we also study. [ABSTRACT FROM AUTHOR]

The present study investigates the possible effects of Hg[SUP2+], Pb[SUP2+], and Cd[SUP2+] on [[SUP3]H]-glutamate binding. To better understand the role of the thiol-disulfide status on the toxicity of such metals toward glutamatergic neurotransmission, we used three thiol chelating agents, 2,3-dimercaptopropanol (BAL), 2,3-dimercaptopropane 1-sulfonate (DMPS), and meso-2,3-dimercaptosuccinic acid (DMSA). Dithiotreitol (DTT) was tested for its ability to prevent metals-induced inhibition on [[SUP3]H]-glutamate binding. Hg[SUP2+] Pb[SUP2+], and Cd[SUP2+] showed a concentration-dependent inhibition on [[SUP3]H]-glutamate binding, and mercury was the most effective inhibitor. BAL did not prevent [[SUP3]H]-glutamate binding inhibition by Hg[SUP2+], Cd[SUP2+], and Pb[SUP2+]. However, DMPS and DMSA prevented the inhibition caused by Cd[SUP2+] and Pb[SUP2+], but not by Hg[SUP2+]. DTT did not prevent the inhibition on [[SUP3]H]-glutamate binding caused by 10 μM Hg[SUP2+]. In contrast, it was able to partially prevent [[SUP3]H]-glutamate binding inhibition caused by 40 μM Pb[SUP2+] and Cd[SUP2+]. These results demonstrated that the heavy metals present an inhibitory effect on [[SUP3]H]-glutamate binding. In addition, BAL was less effective to protect [[SUP3]H]-glutamate binding inhibition caused by these metals than other chelating agents studied. [ABSTRACT FROM AUTHOR]

We apply a universal normal Calabi–Yau algebra to the construction and classification of compact complex n-dimensional spaces with SU(n) holonomy and their fibrations. This algebraic approach includes natural extensions of reflexive weight vectors to higher dimensions and a “dual” construction based on the Diophantine decomposition of invariant monomials. The latter provides recurrence formulas for the numbers of fibrations of Calabi–Yau spaces in arbitrary dimensions, which we exhibit explicitly for some Weierstrass and K3 examples. [ABSTRACT FROM AUTHOR]

By using methods of toric geometry, we investigate compactifications of F-theory on the elliptic Calabi–Yau threefolds. [ABSTRACT FROM AUTHOR]