Fano hypersurfaces and Calabi-Yau supermanifolds

In this paper, we study the geometrical interpretations associated with Sethi's proposed general correspondence between N = 2 Landau-Ginzburg orbifolds with integral \hat{c} and N = 2 nonlinear sigma models. We focus on the supervarieties associated with \hat{c} = 3 Gepner models. In the process, we test a conjecture regarding the superdimension of the singular locus of these supervarieties. The supervarieties are defined by a hypersurface \widetilde{W} = 0 in a weighted superprojective space and have vanishing super-first Chern class. Here, \widetilde{W} is the modified superpotential obtained by adding as necessary to the Gepner superpotential a boson mass term and/or fermion bilinears so that the superdimension of the supervariety is equal to \hat{c}. When Sethi's proposal calls for adding fermion bilinears, setting the bosonic part of \widetilde{W} (denoted by \widetilde{W}_{bos}) equal to zero defines a Fano hypersurface embedded in a weighted projective space. In this case, if the Newton polytope of \widetilde{W}_{bos} admits a nef partition, then the Landau-Ginzburg orbifold can be given a geometrical interpretation as a nonlinear sigma model on a complete intersection Calabi-Yau manifold. The complete intersection Calabi-Yau manifold should be equivalent to the Calabi-Yau supermanifold prescribed by Sethi's proposal.Comment: 24 pages, uses JHEP3.cls; v2: minor corrections, references adde

Strategy Change in Vibrissal Active Sensing during Rat Locomotion

During exploration, rats and other small mammals make rhythmic back-and-forth sweeps of their long facial whiskers (macrovibrissae) [1, 2 and 3]. These “whisking” movements are modulated by head movement [4] and by vibrissal sensory input [5 and 6] and hence are often considered “active” in the Gibsonian sense of being purposive and information seeking [7 and 8]. An important hallmark of active sensing is the modification of the control strategy according to context [9]. Using a task in which rats were trained to run circuits for food, we tested the hypothesis that whisker control, as measured by high-speed videography, changes with contextual variables such as environment familiarity, risk of collision, and availability of visual cues. In novel environments, functionally blind rats moved at slow speeds and performed broad whisker sweeps. With greater familiarity, however, they moved more rapidly, protracted their whiskers further, and showed decreased whisking amplitude. These findings indicate a strategy change from using the vibrissae to explore nearby surfaces to using them primarily for “look ahead.” In environments with increased risk of collision, functionally blind animals moved more slowly but protracted their whiskers further. Sighted animals also showed changes in whisker control strategy with increased familiarity, but these changes were different to those of the functionally blind strain. Sighted animals also changed their vibrissal behavior when visual cues were subsequently removed (by being placed in darkness). These contextual influences provide strong evidence of active control and demonstrate that the vibrissal system provides an accessible model of purposive behavior in mammals

Vanishing refuge? Testing the forest refuge hypothesis in coastal East Africa using genome-wide sequence data for seven amphibians

High‐throughput sequencing data have greatly improved our ability to understand the processes that contribute to current biodiversity patterns. The “vanishing refuge” diversification model is speculated for the coastal forests of eastern Africa, whereby some taxa have persisted and diversified between forest refugia, while others have switched to becoming generalists also present in non‐forest habitats. Complex arrangements of geographical barriers (hydrology and topography) and ecological gradients between forest and non‐forest habitats may have further influenced the region's biodiversity, but elucidation of general diversification processes has been limited by lack of suitable data. Here, we explicitly test alternative diversification modes in the coastal forests using genome‐wide single nucleotide polymorphisms, mtDNA, spatial and environmental data for three forest (Arthroleptis xenodactyloides, Leptopelis flavomaculatus and Afrixalus sylvaticus) and four generalist (Afrixalus fornasini, A. delicatus, Leptopelis concolor, L. argenteus) amphibians. Multiple analyses provide insight about divergence times, spatial population structure, dispersal barriers, environmental stability and demographic history. We reveal highly congruent intra‐specific diversity and population structure across taxa, with most divergences occurring during the late Pliocene and Pleistocene. Although stability models support the existence of some forest refugia, dispersal barriers and demographic models point toward idiosyncratic diversification modes across taxa. We identify a consistent role for riverine barriers in the diversification of generalist taxa, but mechanisms of diversification are more complex for forest taxa and potentially include topographical barriers, forest refugia and ecological gradients. Our work demonstrates the complexity of diversification processes in this region, which vary between forest and generalist taxa, but also for ecologically similar species with shared population boundaries

Leveraging the macro-level environment to balance work and life: an analysis of female entrepreneurs' job satisfaction

This study investigates the interactive effect of female entrepreneurs’ experience of work–life imbalance and gender-egalitarian macro-level conditions on their job satisfaction, with the prediction that the negative linear relationship between work–life imbalance and job satisfaction may be buffered by the presence of women-friendly action resources, emancipative values, and civic entitlements. Data pertaining to 7,392 female entrepreneurs from 44 countries offer empirical support for these predictions. Female entrepreneurs who are preoccupied with their ability to fulfill both work and life responsibilities are more likely to maintain a certain level of job satisfaction, even if they experience significant work–life imbalances, to the extent that they operate in supportive macro-level environments

Explaining the effect of rapid internationalization on horizontal foreign divestment in the retail sector. An extended penrosean perspective

Building on and extending Penrosean logic we argue that rapid international expansion by firms might lead to a breach of Penrosean constraints on efficient expansion and to subsequent divestment of international operations to bring firm scope back into Penrosean constraints. We further predict that intra-regional concentration and international experience moderate the above effect because they influence firms ability to avoid a breach of Penrosean constraints and/or weaken the consequences of such a breach. Using data on the international expansion and divestment of large retail MNEs over the period 2003-2012 we find empirical support for the proposed extended Penrose effect in explaining international divestment as well as for the moderating effects of intra-regional concentration and international experience. Our study contributes to the development of Penrosean logic and to our understanding of the factors that drive firms to divest overseas operations

Kreditbedömningar och Data Warehouse : En studie om riktlinjer för insamling, transformering och inladdning av kreditbedömningsinformation i Data Warehouse

Studien har handlat om att ta fram riktlinjer för hur extrahering, transformering och inladdning (ETL) av kreditbedömningsinformation bör göras när det kommer till att införa ett Data Warehouse (DW). Ett kvalitativt angreppssätt har använts med både en fallstudie och en intervjustudie, där fallstudien genomfördes med Asitis AB som är en systemleverantör förfinans- och reskontrafinansiering (factoring) för att undersöka potentiella affärsmöjligheter med ett DW med kreditbedömningsinformation. Intervjustudien användes för att samla in värdefull information från individer inom alla berörda problemområden, och användes sedan i fallstudien. Resultatet var både framgångsfaktorer och fallgropar för ETL-processen med kreditbedömningsinformation som kan fungera som stöd för organisationer med detta behov. Det har visat sig att ETL-processen för kreditbedömningsinformation utgör ett område med stor potential för affärsmöjligheter, där det krävs hög kompetens, domänkunskap, proaktivitet och juridisk kunskap vid genomförande av ETL-processen