Is dark matter an extra-dimensional effect?

We investigate the possibility that the observed behavior of test particles outside galaxies, which is usually explained by assuming the presence of dark matter, is the result of the dynamical evolution of particles in higher dimensional space-times. Hence, dark matter may be a direct consequence of the presence of an extra force, generated by the presence of extra-dimensions, which modifies the dynamic law of motion, but does not change the intrinsic properties of the particles, like, for example, the mass (inertia). We discuss in some detail several possible particular forms for the extra force, and the acceleration law of the particles is derived. Therefore, the constancy of the galactic rotation curves may be considered as an empirical evidence for the existence of the extra dimensions.Comment: 11 pages, no figures, accepted for publication in MPLA; references adde

Effect of rotational shepherding on demographic and genetic connectivity of calcareous grassland plants

Response to habitat fragmentation may not be generalized among species, in particular for plant communities with a variety of dispersal traits. Calcareous grasslands are one of the most species-rich habitats in Central Europe, but abandonment of traditional management has caused a dramatic decline of calcareous grassland species. In the Southern Franconian Alb in Germany, reintroduction of rotational shepherding in previously abandoned grasslands has restored species diversity, and it has been suggested that sheep support seed dispersal among grasslands. We tested the effect of rotational shepherding on demographic and genetic connectivity of calcareous grassland specialist plants and whether the response of plant populations to shepherding was limited to species dispersed by animals (zoochory). Specifically, we tested competing dispersal models and source and focal patch properties to explain landscape connectivity with patch-occupancy data of 31 species. We fitted the same connectivity models to patch occupancy and nuclear microsatellite data for the herb Dianthus carthusianorum (Carthusian pink). For 27 species, patch connectivity was explained by dispersal by rotational shepherding regardless of adaptations to zoochory, whereas population size (16% species) and patch area (0% species) of source patches were not important predictors of patch occupancy in most species. [Correction made after online publication, February 25, 2014: Population size and patch area percentages were mistakenly inverted, and have now been fixed.] Microsite diversity of focal patches significantly increased the model variance explained by patch occupancy in 90% of the species. For D. carthusianorum, patch connectivity through rotational shepherding explained both patch occupancy and population genetic diversity. Our results suggest shepherding provides dispersal for multiple plant species regardless of their dispersal adaptations and thus offers a useful approach to restore plant diversity in fragmented calcareous grasslands

Directed dispersal by rotational shepherding supports landscape genetic connectivity in a calcareous grassland plant

Directed dispersal by animal vectors has been found to have large effects on the structure and dynamics of plant populations adapted to frugivory. Yet, empirical data are lacking on the potential of directed dispersal by rotational grazing of domestic animals to mediate gene flow across the landscape. Here, we investigated the potential effect of large-flock shepherding on landscape-scale genetic structure in the calcareous grassland plant Dianthus carthusianorum, whose seeds lack morphological adaptations to dispersal to animals or wind. We found a significant pattern of genetic structure differentiating population within grazed patches of three nonoverlapping shepherding systems and populations of ungrazed patches. Among ungrazed patches, we found a strong and significant effect of isolation by distance (r = 0.56). In contrast, genetic distance between grazed patches within the same herding system was unrelated to geographical distance but significantly related to distance along shepherding routes (r = 0.44). This latter effect of connectivity along shepherding routes suggests that gene flow is spatially restricted occurring mostly between adjacent populations. While this study used nuclear markers that integrate gene flow by pollen and seed, the significant difference in the genetic structure between ungrazed patches and patches connected by large-flock shepherding indicates the potential of directed seed dispersal by sheep across the landscape

Conformal Invariance in Einstein-Cartan-Weyl space

We consider conformally invariant form of the actions in Einstein, Weyl, Einstein-Cartan and Einstein-Cartan-Weyl space in general dimensions($>2$) and investigate the relations among them. In Weyl space, the observational consistency condition for the vector field determining non-metricity of the connection can be obtained from the equation of motion. In Einstein-Cartan space a similar role is played by the vector part of the torsion tensor. We consider the case where the trace part of the torsion is the Kalb-Ramond type of field. In this case, we express conformally invariant action in terms of two scalar fields of conformal weight -1, which can be cast into some interesting form. We discuss some applications of the result.Comment: 10 pages, version to appear MPL

The impact of the Internet of Things (IoT) on Servitization: An exploration of changing supply relationships

This research paper explores the emerging potential of IoT technology as an enabler for manufacturers seeking to exploit opportunities for new production, business and operating models. Following an analysis of extant literature and exploration of four in-depth cases, the paper presents four dominant pathways to servitizing the business model through IoT implementation. This first finding is extended in the cross-case analysis, through a categorization of cases into the four pathways, comparing different levels of supplier integration and information exchange. Using this data and categorizations, the paper arrives at certain theoretical propositions regarding the wider impact of IoT technology implementation on information exchange and relational rents through self-enforcing safeguards, risk and financial incentive sharing and lastly transaction cost economics. These propositions lead to the recommendation for suppliers to adopt a servitization pathway of ‘operational service’ models, in order to reap maximum competitive benefit and return on specific investments. This suggests a dependence on the servitization pathway chosen by the supplier, implying that there is no single solution to deal with buyer-supplier relationships in IoT servitization environments

An ecological connectivity network maintains genetic diversity of a flagship wildflower, Pulsatilla vulgaris

Ecological connectivity networks have been proposed as an efficient way to reconnect communities in fragmented landscapes. Yet few studies have evaluated if they are successful at enhancing actual functional connectivity (i.e. realized dispersal or gene flow) of focal species, or if this enhanced connectivity is enough to maintain genetic diversity and fitness of plant populations. Here we test the efficacy of an ecological connectivity network implemented in southern Germany since 1989 to reconnect calcareous grassland fragments through rotational shepherding. We genotyped 1449 individuals from 57 populations and measured fitness-related traits in 10 populations of Puisatilla vulgaris, a flagship species of calcareous grasslands in Europe. We tested if the shepherding network explained functional connectivity in P. vulgaris and if higher connectivity translated to higher genetic diversity and fitness of populations. We found that population-specific F-st was lowest in populations that had high connectivity within the shepherding network, and that well-connected populations within the network had significantly higher genetic diversity than ungrazed and more isolated grazed populations. Moreover, genetic diversity was significantly positively correlated with both seed set and seed mass. Together our results suggest that the implementation of an ecological shepherding network is an effective management measure to maintain functional connectivity and genetic diversity at the landscape scale for a calcareous grassland specialist. Populations with reduced genetic diversity would likely benefit from inclusion, or better integration into the ecological connectivity network. Our study demonstrates the often postulated but rarely tested sequence of positive associations between connectivity, genetic diversity, and fitness at the landscape scale, and provides a framework for testing the efficacy of ecological connectivity networks for focal species using molecular genetic tools.Peer reviewe

PI3 kinase signalling blocks Foxp3 expression by sequestering Foxo factors

Expression of the regulatory T (T reg) cell–associated transcription factor Foxp3 can be induced by signals from the T cell receptor (TCR), interleukin-2 (IL-2), and transforming growth factor (TGF)-β. These signals are integrated by a network involving phosphatidylinositol 3 kinase (PI3K), protein kinase B (PKB; here referred to as Akt), and the mammalian target of rapamycin (mTOR). New studies show that the Foxo proteins Foxo1 and Foxo3a, which are inactivated by Akt, drive Foxp3 expression. These studies therefore explain the negative regulation of Foxp3 by PI3K signaling, and add Foxo proteins to the growing list of nuclear factors capable of modulating Foxp3 expression

An ecological approach to problems of Dark Energy, Dark Matter, MOND and Neutrinos

Modern astronomical data on galaxy and cosmological scales have revealed powerfully the existence of certain dark sectors of fundamental physics, i.e., existence of particles and fields outside the standard models and inaccessible by current experiments. Various approaches are taken to modify/extend the standard models. Generic theories introduce multiple de-coupled fields A, B, C, each responsible for the effects of DM (cold supersymmetric particles), DE (Dark Energy) effect, and MG (Modified Gravity) effect respectively. Some theories use adopt vanilla combinations like AB, BC, or CA, and assume A, B, C belong to decoupled sectors of physics. MOND-like MG and Cold DM are often taken as opposite frameworks, e.g. in the debate around the Bullet Cluster. Here we argue that these ad hoc divisions of sectors miss important clues from the data. The data actually suggest that the physics of all dark sectors is likely linked together by a self-interacting oscillating field, which governs a chameleon-like dark fluid, appearing as DM, DE and MG in different settings. It is timely to consider an interdisciplinary approach across all semantic boundaries of dark sectors, treating the dark stress as one identity, hence accounts for several "coincidences" naturally.Comment: 12p, Proceedings to the 6-th Int. Conf. of Gravitation and Cosmology. Neutrino section expande