Lumps and P-branes in Open String Field Theory

We describe numerical methods for constructing lump solutions in open string field theory. According to Sen, these lumps represent lower dimensional Dp-Branes and numerical evaluation of their energy can be compared with the expected value for the tension. We take particular care of all higher derivative terms inherent in Witten's version of open string field theory. The importance of these terms for off shell phenomena is argued in the text. Detailed numerical calculations done for the case of general $p$ brane show very good agreement with Sen's conjectured value. This gives credence to the conjecture itself and establishes further the usefulness of Witten's version of SFT .Comment: 11 pages, 1 figure, 1 table; v2: small typos correcte

Higher-dimensional study of extensions via torsors

Let S be a site. First we define the 3-category of torsors under a Picard S-2-stack and we compute its homotopy groups. Using calculus of fractions we define also a pure algebraic analogue of the 3-category of torsors under a Picard S-2-stack. Then we describe extensions of Picard S-2-stacks as torsors endowed with a group law on the fibers. As a consequence of such a description, we show that any Picard S-2-stack admits a canonical free partial left resolution that we compute explicitly. Moreover we get an explicit right resolution of the 3-category of extensions of Picard S-2-stacks in terms of 3-categories of torsors. Using the homological interpretation of Picard S-2-stacks, we rewrite this three categorical dimensions higher right resolution in the derived category of abelian sheaves on S.Comment: We change the title and we add new result

Models of forecasting currency rates in the system of managing enterprise’s competitiveness Модели прогнозирования валютных курсов в системе управления конкурентоспособностью предприятия

The article builds up a model of study of behaviour of currency rates with the use of methods of fractality and interconnection between currency rates and factors of their formation, which allows obtaining adequate forecasting in the system of managing competitiveness of metallurgy enterprises and formation of efficient currency policy.В статье построены модели исследования поведения валютных курсов с использованием методов фрактальности и взаимосвязи между валютными курсами и факторами их формирования, что позволит получить адекватные прогнозы в системе управления конкурентоспособностью металлургических предприятий и сформировать эффективную валютную политику

Koszul-Tate Cohomology For an Sp(2)-Covariant Quantization of Gauge Theories with Linearly Dependent Generators

The anti-BRST transformation, in its Sp(2)-symmetric version, for the general case of any stage-reducible gauge theories is implemented in the usual BV approach. This task is accomplished not by duplicating the gauge symmetries but rather by duplicating all fields and antifields of the theory and by imposing the acyclicity of the Koszul-Tate differential. In this way the Sp(2)-covariant quantization can be realised in the standard BV approach and its equivalence with BLT quantization can be proven by a special gauge fixing procedure.Comment: 13 pages, Latex, To Be Published in International Journal of Modern Physics

The triticeous cartilage — redefining of morphology, prevalence and function

Background: Triticeous cartilage is a small cartilaginous component of the laryngeal skeleton. This cartilage, located in posterior end of the thyrohyoid ligament, presents in different shapes. Radiological studies indicate clinical and anatomical importance of the triticeous cartilage but these studies have limited information due to inadequate inspection method. Computed tomographic angiography is able to evaluate the triticeous cartilage with using three-dimensional images in more detail. The aim of this study is to describe prevalence and morphological properties of the triticeous cartilage. Materials and methods: We examined computed tomographic angiography images of 746 patients (368 women, 378 men) retrospectively. Shapes, calcification degrees, volumes, lengths and wideness of the triticeous cartilage were evaluated by OsiriX-Lite software. Results: According to our results, triticeous cartilage presents common in the examined population (68.1%). The prevalence of the triticeous cartilage was higher in men than in women. We also found that the degree of calcification was not related with age and gender. Conclusions: Clinical importance of the triticeous cartilage is that it could be misdiagnosed with atherosclerosis in common carotid artery because the triticeous cartilage is located almost at same level as the bifurcation of the common carotid artery. Therefore, clinicians should be aware about the triticeous cartilage

Compact F-theory GUTs with U(1)_PQ

We construct semi-local and global realizations of SU(5) GUTs in F-theory that utilize a U(1)_PQ symmetry to protect against dimension four proton decay. Symmetries of this type, which assign charges to H_u and H_d that forbid a tree level \mu term, play an important role in scenarios for neutrino physics and gauge mediation that have been proposed in local F-theory model building. As demonstrated in arXiv:0906.4672, the presence of such a symmetry implies the existence of non-GUT exotics in the spectrum, when hypercharge flux is used to break the GUT group and to give rise to doublet-triplet splitting. These exotics are of precisely the right type to solve the unification problem in such F-theory models and might also comprise a non-standard messenger sector for gauge mediation. We present a detailed description of models with U(1)_PQ in the semi-local regime, which does not depend on details of any specific Calabi-Yau four-fold, and then specialize to the geometry of arXiv:0904.3932 to construct three-generation examples with the minimal allowed number of non-GUT exotics. Among these, we find a handful of models in which the D3-tadpole constraint can be satisfied without requiring the introduction of anti-D3-branes. Finally, because SU(5) singlets that carry U(1)_PQ charge may serve as candidate right-handed neutrinos or can be used to lift the exotics, we study their origin in compact models and motivate a conjecture for how to count their zero modes in a semi-local setting.Comment: 73 pages, 5 figures, v2: minor corrections to 4.3 and 6.3.1, reference adde