Predicting the optical observables for nucleon scattering on even-even actinides

Previously derived Lane consistent dispersive coupled-channel optical model for nucleon scattering on $^{232}$Th and $^{238}$U nuclei is extended to describe scattering on even-even actinides with $Z=$90--98. A soft-rotator-model (SRM) description of the low-lying nuclear structure is used, where SRM Hamiltonian parameters are adjusted to the observed collective levels of the target nucleus. SRM nuclear wave functions (mixed in $K$ quantum number) have been used to calculate coupling matrix elements of the generalized optical model. The "effective" deformations that define inter-band couplings are derived from SRM Hamiltonian parameters. Conservation of nuclear volume is enforced by introducing a dynamic monopolar term to the deformed potential leading to additional couplings between rotational bands. Fitted static deformation parameters are in very good agreement with those derived by Wang and collaborators using the Weizs\"acker-Skyrme global mass model (WS4), allowing to use the latter to predict cross section for nuclei without experimental data. A good description of scarce "optical" experimental database is achieved. SRM couplings and volume conservation allow a precise calculation of the compound-nucleus formation cross sections, which is significantly different from the one calculated with rigid-rotor potentials coupling the ground-state rotational band. Derived parameters can be used to describe both neutron and proton induced reactions.Comment: 6 pages, 4 figures, 5 table

Multiple positive solutions of parabolic systems with nonlinear, nonlocal initial conditions

In this paper we study the existence, localization and multiplicity of positive solutions for parabolic systems with nonlocal initial conditions. In order to do this, we extend an abstract theory that was recently developed by the authors jointly with Radu Precup, related to the existence of fixed points of nonlinear operators satisfying some upper and lower bounds. Our main tool is the Granas fixed point index theory. We also provide a non-existence result and an example to illustrate our theory.Comment: 28 pages, 1 figure. arXiv admin note: text overlap with arXiv:1401.135

Applications of BGP-reflection functors: isomorphisms of cluster algebras

Given a symmetrizable generalized Cartan matrix $A$, for any index $k$, one can define an automorphism associated with $A,$ of the field $\mathbf{Q}(u_1, >..., u_n)$ of rational functions of $n$ independent indeterminates $u_1,..., u_n.$ It is an isomorphism between two cluster algebras associated to the matrix $A$ (see section 4 for precise meaning). When $A$ is of finite type, these isomorphisms behave nicely, they are compatible with the BGP-reflection functors of cluster categories defined in [Z1, Z2] if we identify the indecomposable objects in the categories with cluster variables of the corresponding cluster algebras, and they are also compatible with the "truncated simple reflections" defined in [FZ2, FZ3]. Using the construction of preprojective or preinjective modules of hereditary algebras by Dlab-Ringel [DR] and the Coxeter automorphisms (i.e., a product of these isomorphisms), we construct infinitely many cluster variables for cluster algebras of infinite type and all cluster variables for finite types.Comment: revised versio

Galois coverings of weakly shod algebras

We investigate the Galois coverings of weakly shod algebras. For a weakly shod algebra not quasi-tilted of canonical type, we establish a correspondence between its Galois coverings and the Galois coverings of its connecting component. As a consequence, we show that a weakly shod algebra is simply connected if and only if its first Hochschild cohomology group vanishes.Comment: Some references were added. The proof of Lemma 6.5 was modifie

Measures to promote renewable energy for electricity generation in Algeria

Algeria has enormous renewable energy potential. However, fossil fuels remain the main electricity generation source, and the country is the third largest CO2 emitter in Africa. Algeria is also particularly vulnerable to climate change. Therefore, a set of actions related to energy, forests, industry and waste sectors have been programmed, over the period 2015–2030, and the government action program has given priority to promote renewable energy. In this sense, Algeria is committed to significantly promote investment in renewable energy, during the period 2020–2030. Thus by 2030, renewable electricity production capacity will achieve 22,000 MW, representing 27% of total electricity generation. This paper analyzes the electricity generation measures implemented in Algeria to reach the required energy mix, the legislative framework, financial aid, the feed-in tariff system, the tax incentives, and the tender and auctions undertaken. The analyses reveal that, although the electricity price premium policy has not been revoked, the newly enacted tender scheme is designed to become the standard procedure for launching renewable energy projects in Algeria in the coming years

Managing the Risk of Stranded Assets in Agriculture and Forestry

To date, much of the research into stranded assets – broadly defined as assets incurring significant unanticipated or premature write-downs or devaluations – has focused on the fossil fuel sector. However, not least in the context of the 2015 Paris Agreement, and with growing understanding that climate change may become a major factor in the creation of stranded assets, it has become clear that it is not just the energy sector that will be affected. Assets in agriculture and forestry may also be at risk of stranding, because of physical impacts such as drought and desertification as well as through regulatory and technological change.The risk of stranding is particularly high in production regions where natural forests are being cleared for agricultural use. Other regions at high risk are those where climate change is predicted to have impacts that will severely disrupt production cycles or shift production patterns. In addition, strong low-carbon development plans can affect the regulatory frameworks that govern the agriculture and forestry sectors, bringing further risks of stranding.Stranding risks have a potential impact on the various actors positioned along the supply chain for agriculture and forest commodities. They include the land- or rights-owners, the owners of infrastructure related to the transport and processing of commodities, consumer companies and investors.The faster the pace of decarbonization, or the more pronounced the impacts of climate change, the greater the chance of asset stranding and the higher the likelihood of economic, social and political impacts. The prospect of asset stranding could be sufficient to cause potentially affected groups to impede efforts towards low-carbon development, but this possibility has not been sufficiently accounted for in the national low-carbon development plans of either developed or developing economies. As a result, there is a potential risk to the implementation of such plans.This paper includes case studies of stranding risk in Brazil, Malaysia and Liberia. In these countries, there are potentially significant risks of stranding, both from regulation and climate change impacts. However, there has been very little consideration of these risks by policymakers, and there are significant information gaps.Further research is necessary in the following areas: analysing the outlook for biofuels to assess the risk of stranding and the possible impacts of new technology; assessing the physical impacts of extreme weather events on investments, taking into account the role of the insurance industry and price fluctuations; and determining whether growing consumer preferences for 'sustainable' products contribute to the risk of stranding in agriculture and forestry.Such research could be used to initiate discussions within producer countries about the risk of stranded assets given their national strategies and policies, and in light of the available evidence of the physical impacts of climate change, in order to identify the options for both mitigating and managing that risk

The multiplicativity of fixed point invariants

We prove two general factorization theorems for fixed-point invariants of fibrations: one for the Lefschetz number and one for the Reidemeister trace. These theorems imply the familiar multiplicativity results for the Lefschetz and Nielsen numbers of a fibration. Moreover, the proofs of these theorems are essentially formal, taking place in the abstract context of bicategorical traces. This makes generalizations to other contexts straightforward.Comment: 24 pages. v3: final version, to appear in AG