Viscosity methods giving uniqueness for martingale problems

Let $E$ be a complete, separable metric space and $A$ be an operator on $C_b(E)$. We give an abstract definition of viscosity sub/supersolution of the resolvent equation $\lambda u-Au=h$ and show that, if the comparison principle holds, then the martingale problem for $A$ has a unique solution. Our proofs work also under two alternative definitions of viscosity sub/supersolution which might be useful, in particular, in infinite dimensional spaces, for instance to study measure-valued processes. We prove the analogous result for stochastic processes that must satisfy boundary conditions, modeled as solutions of constrained martingale problems. In the case of reflecting diffusions in $D\subset {\bf R}^d$, our assumptions allow $D$ to be nonsmooth and the direction of reflection to be degenerate. Two examples are presented: A diffusion with degenerate oblique direction of reflection and a class of jump diffusion processes with infinite variation jump component and possibly degenerate diffusion matrix

Existence and uniqueness of obliquely reflecting Brownian motion in nonpolyhedral, piecewise smooth cones, with an example of application to diffusion approximation of bandwidth sharing queues

The paper considers the stochastic differential equation with reflection that defines a semimartingale Brownian motion in a nonpolyhedral, piecewise smooth cone, with radially constant direction of reflection on each face. Existence and uniqueness in distribution of the solution are proved, under suitable assumptions. The assumptions are shown to be verified by the stochastic differential equation with reflection satisfied by the conjectured limit, under diffusive space-time scaling, of the workload process in an example of stochastic network operating under a 2-fair bandwidth sharing policy, thus ensuring that the conjectured limit is uniquely characterized. This is a key step in proving diffusion approximation for the network

Co-axial wet-spinning in 3D Bioprinting: state of the art and future perspective of microfluidic integration

Nowadays, 3D bioprinting technologies are rapidly emerging in the field of tissue engineering and regenerative medicine as effective tools enabling the fabrication of advanced tissue constructs that can recapitulate in vitro organ/tissue functions. Selecting the best strategy for bioink deposition is often challenging and time consuming process, as bioink properties-in the first instance, rheological and gelation-strongly influence the suitable paradigms for its deposition. In this short review, we critically discuss one of the available approaches used for bioprinting-namely co-axial wet-spinning extrusion. Such a deposition system, in fact, demonstrated to be promising in terms of printing resolution, shape fidelity and versatility when compared to other methods. An overview of the performances of co-axial technology in the deposition of cellularized hydrogel fibres is discussed, highlighting its main features. Furthermore, we show how this approach allows (i) to decouple the printing accuracy from bioink rheological behaviour-thus notably simplifying the development of new bioinks- A nd (ii) to build heterogeneous multi-materials and/or multicellular constructs that can better mimic the native tissues when combined with microfluidic systems. Finally, the ongoing challenges and the future perspectives for the ultimate fabrication of functional constructs for advanced research studies are highlighted. © 2018 IOP Publishing Ltd

Diritto e Religione. Percorsi interdisciplinari e cartografia dei saperi

The author means to survey the symbolic, narrative and memorial process by which legal traditions were established, by probing into unsuspected connections between historical constructions by a legal and normative order on the one side, and the intellectual and imaginative scope of an economy of salvation on the other

The English Katéchon. La mediazione teologico-politica in epoca Tudor

The essay discusses the protean shapes of the politics of memory which conformed English tradition. The intellectual construction of a ‘remembered past’ was inscribed within a theological promise of redemption and salvation; the millenaristic thought created a visionary imagination and supported the recognition of antichristic and katechontic bodies. Moving from these premises, the Author highlights the pivotal role played by Queen Elizabeth I in giving substance to English memory. The main purpose is to investigate the process of cultural negotiation which governed the onto juridical threshold between Elizabeth’s Flesh (that is her natural, physical, female and even sexual consistence) and Elizabeth’s body of sovereignty. The canonical representation construed what, in a very original manner, the Author defines as Katechontic Elizabeth, making an adjectival use of the greek word katechon with its strong theological ascendancy. According to this approach, Elizabeth was depicted as the mundane force destined to fight against the Antichrist, historically embodied by the Roman Pope. In this framework the Author outlines the multifarious devices used to legitimate the cult of the Virgin Queen or, more incisively, to transform a virginal flesh into a body of salvation, evocatively into a katechontic body. They fundamentally were: an apocalyptic narrative, an apologetic plot, the projection of a millenaristic order and a redundant iconography.The essay discusses the protean shapes of the politics of memory which conformed English tradition. The intellectual construction of a ‘remembered past’ was inscribed within a theological promise of redemption and salvation; the millenaristic thought created a visionary imagination and supported the recognition of antichristic and katechontic bodies. Moving from these premises, the Author highlights the pivotal role played by Queen Elizabeth I in giving substance to English memory. The main purpose is to investigate the process of cultural negotiation which governed the onto juridical threshold between Elizabeth’s Flesh (that is her natural, physical, female and even sexual consistence) and Elizabeth’s body of sovereignty. The canonical representation construed what, in a very original manner, the Author defines as Katechontic Elizabeth, making an adjectival use of the greek word katechon with its strong theological ascendancy. According to this approach, Elizabeth was depicted as the mundane force destined to fight against the Antichrist, historically embodied by the Roman Pope. In this framework the Author outlines the multifarious devices used to legitimate the cult of the Virgin Queen or, more incisively, to transform a virginal flesh into a body of salvation, evocatively into a katechontic body. They fundamentally were: an apocalyptic narrative, an apologetic plot, the projection of a millenaristic order and a redundant iconography

Ret and Etv4 Promote Directed Movements of Progenitor Cells during Renal Branching Morphogenesis

Branching morphogenesis of the epithelial ureteric bud forms the renal collecting duct system and is critical for normal nephron number, while low nephron number is implicated in hypertension and renal disease. Ureteric bud growth and branching requires GDNF signaling from the surrounding mesenchyme to cells at the ureteric bud tips, via the Ret receptor tyrosine kinase and coreceptor Gfrα1; Ret signaling up-regulates transcription factors Etv4 and Etv5, which are also critical for branching. Despite extensive knowledge of the genetic control of these events, it is not understood, at the cellular level, how renal branching morphogenesis is achieved or how Ret signaling influences epithelial cell behaviors to promote this process. Analysis of chimeric embryos previously suggested a role for Ret signaling in promoting cell rearrangements in the nephric duct, but this method was unsuited to study individual cell behaviors during ureteric bud branching. Here, we use Mosaic Analysis with Double Markers (MADM), combined with organ culture and time-lapse imaging, to trace the movements and divisions of individual ureteric bud tip cells. We first examine wild-type clones and then Ret or Etv4 mutant/wild-type clones in which the mutant and wild-type sister cells are differentially and heritably marked by green and red fluorescent proteins. We find that, in normal kidneys, most individual tip cells behave as self-renewing progenitors, some of whose progeny remain at the tips while others populate the growing UB trunks. In Ret or Etv4 MADM clones, the wild-type cells generated at a UB tip are much more likely to remain at, or move to, the new tips during branching and elongation, while their Ret−/− or Etv4−/− sister cells tend to lag behind and contribute only to the trunks. By tracking successive mitoses in a cell lineage, we find that Ret signaling has little effect on proliferation, in contrast to its effects on cell movement. Our results show that Ret/Etv4 signaling promotes directed cell movements in the ureteric bud tips, and suggest a model in which these cell movements mediate branching morphogenesis

A dynamic CGE modelling approach for analyzing trade-offs in climate change policy options: the case of Green Climate Fund

38 p.We investigate the trade-offs between economic growth and low carbon targets for developing and developed countries in the period up to 2035. Policy options are evaluated with an original version of the dynamic CGE model GDynE. Abatement costs appear to be strongly detrimental to economic growth for developing countries. We investigate options for reducing these costs that are consistent with a green growth strategy. We show that Green Climate Fund financed through a levy on carbon taxation can benefit all parties, and larger benefits are associated with investment of the Green Climate Fund to foster energy efficiency in developing countries

Local topographic and edaphic factors largely predict shrub encroachment in Mediterranean drylands

Shrub encroachment influences several ecosystem services in drylands worldwide. Yet, commonly used strategies to reduce encroachment show a low medium-term success, calling for a better understanding of its causes. Previous works identified multiple drivers responsible for this phenomenon, including anthropogenic and environmental causes. However, the relative effect of climate, topography and edaphic factors on shrub encroachment is not fully understood nor has been properly quantified in Mediterranean Basin drylands. Also, understanding how these drivers lead to changes in plant communities' functional traits associated to shrub encroachment is crucial, considering traits influence ecosystem processes and associated ecosystem services. Here, we studied the understory of a Mediterranean dryland ecosystem composed of savanna-like Holm-oak woodlands, along a regional climatic gradient. We specifically assessed (i) how climatic, topographic and edaphic factors influence understory relative shrub cover (RSC) and (ii) their direct and indirect effects (via RSC) on plant functional traits. We studied the mean and diversity of 12 functional traits related to plant regeneration, establishment, and dispersal, at the community-level. We found that, under similar low-intensity land use, topographic and edaphic factors, namely slope variations and soil C:N ratio, were the most important predictors of shrub encroachment, determining communities' functional characteristics. Climate, namely summer precipitation, had a much lesser influence. Our model explained 52% of the variation in relative shrub cover. Climate had a stronger effect on a set of functional traits weakly involved in shrub encroachment, related to flowering and dispersal strategies. We show that shrub encroachment is largely predicted by topo-edaphic factors in Mediterranean drylands subject to conventional low-intensity land use. Hence, management strategies to reduce encroachment need to take these drivers into account for efficient forecasting and higher cost-effectiveness. Our results suggest that climate change might not greatly impact shrub encroachment in the Mediterranean Basin, but may affect functional structure and reduce functional diversity of plant communities, thus affecting ecosystem functioning.info:eu-repo/semantics/publishedVersio