Tibetan Plateau Grassland Protection: Tibetan Herders\u27 Ecological Conception Versus State Policies

The establishment of the “Three Rivers’ Sources Nature Reserve” in 2002 - one of China’s largest ecological protection projects - has had a major impact on the lives of Tibetan nomadic herders. This paper examines the ecological viewpoints of Tibetan herders, their conceptions of grassland protection and what they believe to be the best strategies to solve grazing problems. According to the Chinese authorities, the Nature Reserve was established to protect the grasslands, as well as the sources of China’s three major rivers – the Yellow River, the Yangtse and the Mekong. Grazing bans and flock reduction have been two recurring measures in this ecological protection project. Tibetan herders have also often been forced to settle down in new purpose built villages. These “ecological migrations”, as they are referred to in State environmental discourse, are also related to State policies to bolster security through population surveillance and territorial control. Therefore, in this complex context, ecological strategies are combined with political interests. To provide an alternative reading to the existing expert analyses of ecological problems and State reports on grassland and grazing problems, my paper focus on what Tibetan herders, resettled in new villages, think about these topics. Comparing their views against State discourse and policies, it is evident that herders have a different perception of the causes of the current ecological problems and propose alternative solutions, showing a high degree of consciousness of and active concern over grassland problems. Finally, I will argue that, although the ‘ecological migrations’ are often presented as the trigger of the settling of Tibetan nomads, the new resettlement villages are just the latest step in a much longer process of sedentarization, which had already started in the 1980s with the grasslands’ fencing policy

Pattern invariance for reaction-diffusion systems on complex networks

Given a reaction-diffusion system interacting via a complex network, we propose two different techniques to modify the network topology while preserving its dynamical behaviour. In the region of parameters where the homogeneous solution gets spontaneously destabilized, perturbations grow along the unstable directions made available across the networks of connections, yielding irregular spatio-temporal patterns. We exploit the spectral properties of the Laplacian operator associated to the graph in order to modify its topology, while preserving the unstable manifold of the underlying equilibrium. The new network is isodynamic to the former, meaning that it reproduces the dynamical response (pattern) to a perturbation, as displayed by the original system. The first method acts directly on the eigenmodes, thus resulting in a general redistribution of link weights which, in some cases, can completely change the structure of the original network. The second method uses localization properties of the eigenvectors to identify and randomize a subnetwork that is mostly embedded only into the stable manifold. We test both techniques on different network topologies using the Ginzburg-Landau system as a reference model. Whereas the correlation between patterns on isodynamic networks generated via the first recipe is larger, the second method allows for a finer control at the level of single nodes. This work opens up a new perspective on the multiple possibilities for identifying the family of discrete supports that instigate equivalent dynamical responses on a multispecies reaction-diffusion system

Evolution of Model-Based System Engineering Methodologies for the Design of Space Systems in the Advanced Stages of the Project (Phases B-C)

The main topic of the present work is addressed to the evaluation of the possible improvements that can be achieved with the integration of Model Based System Engineering Methodologies in the advanced phases of space project. In particular a model based approach will be proposed for two main aspects directly affecting the design phases of complex systems. The first one is represented by the management of design options that becomes difficult to monitor as the project proceeds, increasing the amount of data to take into consideration. The other one is represented by the integration between Multidisciplinary Design Optimization (MDO) techniques and a Model Based System Engineering (MBSE) environment. The aim of the research activity concerns the feasibility of such connection in order to assess actual advantages and possible drawbacks. In this last case the objective is to show how the Multidisciplinary Design Optimization (MDO) methods may be managed in the context of a MBSE environment with respect to the traditional design approach. In particular this analysis is addressed to the demonstration of the benefits of MBSE methodology and MDO techniques considering a space system reference case. In the first part of the thesis a briefly description of the problem statement is introduced to better explain the subjects of the following chapters. In particular the reasons and the related purposes that have animated this work are considered. In the next sec..on the state of the art about the considered approach is presented, providing a background for the following activities. In this context a wider analysis of the motivations and thesis objectives is considered. The following chapters deals with the survey and critical assessment of the main work related to this thesis. The analysis, design and implementation of the proposed framework are considered in the next sections. At the end of this part the results obtained are presented without arguing about the related benefits or drawbacks, which are considered in the following. A critical assessment of the results is then presented, analyzing the main contributions and related disadvantages with respect to the current approaches. In the next sec..on the incoming activities and further developments are presented. The final part concerns at last the summary conclusions of the work done

The second will be first: competition on directed networks

Multiple sinks competition is investigated for a walker diffusing on directed complex networks. The asymmetry of the imposed spatial support makes the system non transitive. As a consequence, it is always possible to identify a suitable location for the second absorbing sink that screens at most the flux of agents directed against the first trap, whose position has been preliminarily assigned. The degree of mutual competition between pairs of nodes is analytically quantified through apt indicators that build on the topological characteristics of the hosting graph. Moreover, the positioning of the second trap can be chosen so as to minimize, at the same time the probability of being in turn shaded by a thirdly added trap. Supervised placing of absorbing traps on a asymmetric disordered and complex graph is hence possible, as follows a robust optimization protocol. This latter is here discussed and successfully tested against synthetic data

Spectral control for ecological stability

A system made up of N interacting species is considered. Self-reaction terms are assumed of the logistic type. Pairwise interactions take place among species according to different modalities, thus yielding a complex asymmetric disordered graph. A mathematical procedure is introduced and tested to stabilise the ecosystem via an {\it ad hoc} rewiring of the underlying couplings. The method implements minimal modifications to the spectrum of the Jacobian matrix which sets the stability of the fixed point and traces these changes back to species-species interactions. Resilience of the equilibrium state appear to be favoured by predator-prey interactions

Slope instability in the Bastardo Basin (Umbria, Central Italy) ? The landslide of Barattano

International audienceThe Bastardo Basin is one of the classics Apenninic intermontane basins of central Italy. They are en-closed tectonic basins (graben and semigraben) with high anthropization, but with high vulnerability, too (seismic, hydrogeological and geomorphological). The paper concerns some aspects about slope instability in the Bastardo Basin as part of a wider research, which aims to actually define the characteristics of the liability to landslides of the Apenninic intermontane basins. In particular lithological, stratigraphical and hydrogeological conditions are analysed under which a landslide near village of Barattano has developed. This mass movement, at different times, produced partial or total occlusion of the torrent Puglia. Here geognostic investigations together with laboratory tests and subsequent monitoring of landslide area were carried out. A back analysis, based on limit equilibrium solutions for the factor of safety of the slope, provided the residual strenght properties of the soil mass along the sliding surface. The landslide of Barattano is representative of a very frequent situation (in terms of type, factors and causes of the movement, possible development of the movement) not only within Bastardo Basin, but in general within Apenninic intermontane basins, too. The study of landslide and the design of appropriate remedial measures are of great importance in terms of prevention and mitigation of geologic-hydraulic risk in Apenninic intermontane basins

Endogenous crisis waves: a stochastic model with synchronized collective behavior

We propose a simple framework to understand commonly observed crisis waves in macroeconomic Agent Based models, that is also relevant to a variety of other physical or biological situations where synchronization occurs. We compute exactly the phase diagram of the model and the location of the synchronization transition in parameter space. Many modifications and extensions can be studied, confirming that the synchronization transition is extremely robust against various sources of noise or imperfections.Comment: 5 pages, 3 figures. This paper is part of the CRISIS project, http://www.crisis-economics.e

Global topological control for synchronized dynamics on networks

A general scheme is proposed and tested to control the symmetry breaking instability of a homogeneous solution of a spatially extended multispecies model, defined on a network. The inherent discreteness of the space makes it possible to act on the topology of the inter-nodes contacts to achieve the desired degree of stabilization, without altering the dynamical parameters of the model. Both symmetric and asymmetric couplings are considered. In this latter setting the web of contacts is assumed to be balanced, for the homogeneous equilibrium to exist. The performance of the proposed method are assessed, assuming the Complex Ginzburg-Landau equation as a reference model. In this case, the implemented control allows one to stabilize the synchronous limit cycle, hence time-dependent, uniform solution. A system of coupled real Ginzburg-Landau equations is also investigated to obtain the topological stabilization of a homogeneous and constant fixed point