Extrinsic curvature effects in brane-world scenarios

We consider models of bosons on curved 3+1 dimensional space-time embedded in a higher dimensional flat ambient space. We propose to derive (rather than postulate) equations of motions by assuming that a standard Klein-Gordon field on ambient space is restricted to space-time by a strong confining potential. This leads to a modified Klein-Gordon equation on space-time which includes, in addition to the standard terms, a term with a so-called induced potential which depends on intrinsic- and extrinsic curvature of the embedded space-time but not on the details of the confining potential. We compute this induced potential for natural, simple embeddings of Schwarzschild- and Robertson-Walker space-times. We also discuss possible observable implications of our results and, in particular, propose and study an extension of a standard model of cosmological inflation taking into account extrinsic curvature effects. We show that the modified model allows for a solution where the scaling function vanishes like a power law with exponent 0.6830.. at some initial time.Comment: 24 pages; v2: typos correcte

Alternating Least-Squares for Low-Rank Matrix Reconstruction

For reconstruction of low-rank matrices from undersampled measurements, we develop an iterative algorithm based on least-squares estimation. While the algorithm can be used for any low-rank matrix, it is also capable of exploiting a-priori knowledge of matrix structure. In particular, we consider linearly structured matrices, such as Hankel and Toeplitz, as well as positive semidefinite matrices. The performance of the algorithm, referred to as alternating least-squares (ALS), is evaluated by simulations and compared to the Cram\'er-Rao bounds.Comment: 4 pages, 2 figure

Relevance Singular Vector Machine for low-rank matrix sensing

In this paper we develop a new Bayesian inference method for low rank matrix reconstruction. We call the new method the Relevance Singular Vector Machine (RSVM) where appropriate priors are defined on the singular vectors of the underlying matrix to promote low rank. To accelerate computations, a numerically efficient approximation is developed. The proposed algorithms are applied to matrix completion and matrix reconstruction problems and their performance is studied numerically.Comment: International Conference on Signal Processing and Communications (SPCOM), 5 page

Эволюция диагностических критериев транзиторных ишемических атак

МОЗГА ГОЛОВНОГО ИШЕМИЯ ТРАНЗИТОРНАЯНЕВРОЛОГИЧЕСКИЕ ПРОЯВЛЕНИ

T-Duality of Green-Schwarz Superstrings on AdS(d) x S(d) x M(10-2d)

We verify the self-duality of Green-Schwarz supercoset sigma models on AdS$_d \times S^d$ backgrounds (d=2,3,5) under combined bosonic and fermionic T-dualities without gauge fixing kappa symmetry. We also prove this property for superstrings on AdS$_d \times S^d \times S^d$ (d=2,3) described by supercoset sigma models with the isometries governed by the exceptional Lie supergroups $D(2,1;\alpha)$ (d=2) and $D(2,1;\alpha)\times D(2,1;\alpha)$ (d=3), which requires an additional T-dualisation along one of the spheres. Then, by taking into account the contribution of non-supercoset fermionic modes (up to the second order), we provide evidence for the T-self-duality of the complete type IIA and IIB Green-Schwarz superstring theory on AdS$_d\times S^d \times T^{10-2d}$ (d=2,3) backgrounds with Ramond-Ramond fluxes. Finally, applying the Buscher-like rules to T-dualising supergravity fields, we prove the T-self-duality of the whole class of the AdS$_d\times S^d \times M^{10-2d}$ superbackgrounds with Ramond-Ramond fluxes in the context of supergravity.Comment: v2: 57 pages, 1 figure, typos fixed and clarifications added, version to appear in JHE

Strong positive relationships between eDNA concentrations and biomass in juvenile and adult pike (Esox lucius) under controlled conditions: Implications for monitoring

Reliable abundance information is the foundation for managing aquatic resources. Species with low catchability are, however, often overlooked in monitoring programmes. Thus, governing bodies lack the data necessary to make well-informed management decisions. Environmental DNA (eDNA) can produce quantitative estimates of fish abundances, but the precision varies greatly depending on the species and system. It is, therefore, necessary to evaluate its performance and investigate how fish biomass and density affects eDNA dynamics on a case-by-case basis before eDNA-based monitoring can be a viable option. Here, we evaluate how biomass and density of an ecologically and socioeconomically important top predator, the Northern pike (Esox lucius), relate to eDNA concentrations in controlled aquarium and mesocosm experiments. We carried out experiments using both juvenile and adult individuals and evaluated eDNA, biomass and density relationships at three different time points using a previously developed TaqMan assay, targeting the cytochrome oxidase I gene. We also evaluated the performance of multiple extraction methods (DNeasy Blood & Tissue kit, DNeasy PowerWater kit, and Chelex 100), and filtering systems (single- vs. double-membrane filters). The results from both pike experiments showed a strong positive linear relationship between eDNA concentration and pike biomass (R2 = 0.74 – 0.87). Levels of eDNA dropped drastically within the initial 24 h of juvenile pike being removed from the aquaria, and low levels were detectable for up to 308 h. Of the extraction methods, Chelex 100 yielded the highest DNA concentration, offering a quick and cost-effective alternative compared with existing widely used extraction methods. Using double membrane filters of different material showed no increase in DNA yield regardless of the extraction method but it allowed more water to be processed. Although several challenges remain, our results show that eDNA holds promise to become a useful tool for monitoring fish biomass in natural environments

A dynamical symmetry for supermembranes

A dynamical symmetry for supersymmetric extended objects is given.Comment: 3 page