Transition Dynamics

Mountaintop removal/valley fill mining (MTR/VF) brings an array of environmental impacts at every stage of the process, many of which directly and indirectly affect local hydrology and water quality. Analysis of the practice in the region of its heaviest use, the Central Appalachian coalfields, has revealed two primary causes of such degradation: valley fills and coal slurry impoundments. When overburden from a mountaintop removal mine is dumped into the nearby valley, it significantly increases the total dissolved solids (TDS) concentration, metal concentration, and pH of the water, significantly degrading the water quality and stream activity and ultimately causing a loss of biodiversity in local ecosystems. When coal from the mine site is processed and cleaned, the highly toxic slurry byproduct must be stored in massive impoundments, where the risk of spilling into surface or groundwater is a constant threat. Although the Surface Mining Control and Reclamation Act of 1977 (SMCRA) requires the reclamation of such disturbed land and water to reduce the impact of valley filling, current technologies and a general misunderstanding of ecological processes make this impossible, leaving most mitigation of the impact up to new federal and state litigation. Unfortunately, recent changes to the Clean Water Act (CWA) have effectively sanctioned valley fills, requiring that any call for stricter enforcement of environmental regulation on the matter begin with scientifically addressing such discrepancies. In contrast, very little regulation has governed the construction and maintenance of slurry impoundments since the first major spill incident, but a more recent incident of greater magnitude has incited demand for new regulatory frameworks and technology to reduce the risk of impact and the volume of slurry produced. This paper will review the history of MTR/VF, its process and environmental impacts, and the steps that can be taken to mitigate such impacts.

In this article a new Modelica library to model vehicle power trains is discussed. An overview of the elements within the library is given, such as planetary gearsets, laminar clutches, torque losses, driver, warm up model. The library is demonstrated through the discussion of two illustrative examples, for drive cycle fuel consumption prediction and for investigating gearshift transition dynamics of an automatic gearbox. Together with the Modelica simulation environment Dymola, this library is suited and used for HIL (Hardware-In-the-Loop) simulations.

An R&D based endogenous growth - applied general equilibrium model is developed from an underlying analytical model which combines Romer's capital variety with Grossman and Helpman's multi-sector open economy model. The transitional dynamics of the analytical model are derived. For numerical implementation, a time discrete empirical model, with an Armington structure, is fit to East Asian data of the social

Les changements dans la couverture et utilisation du terrain, les modifications des circuits de l’énergie et les changements climatiques sont constituants des « changements globales », terme incluant tous les impacts humains sous les complexes des systèmes socio-écologiques. La plupart des auteurs faite une connexion entre la pression sous l’environnement et les forces socio-économiques, considérant que le processus de transition économique et la conscience environnementale réduite produisent problèmes environnementaux sérieux. Cette recherche s’agit de l’investigation des impacts environnementaux par les dynamiques de transition dans longues périodes réfléchies par des changements dans la couverture et utilisation du terrain dans la région de développement roumaine sud-ouest, en connexion avec le déclin post-socialiste de l’économie, aggravé par le fait que beaucoup des villes ont perdu leur fonction industrielle. La méthodologie est basée sur l’allocation de des changements dans la couverture et utilisation du terrain indiquées par les données CORINE entre 1990-2000 et 2000-2006 aux dynamiques de transition spécifique, calculant la surface affectée par chaque type, et utilisant le kriging commun pour trouvant les zones le plus affectées. Les résultats indiquent que le plus importantes dynamiques sont le forestage (afforestation ou reforestation), abandon et développement de l’agriculture, déforestation et urbanisation pour la première période, et le forestage (afforestation ou reforestation), déforestation, abandon de l’agriculture et urbanisation pendant la deuxième. Donné que la colonisation naturelle des parcelles agricoles abandonnées par la végétation forestière pourrait être erronément classifiée comme foretage, les causes majeurs peuvent être attribuées au déclin de l’économie, soutenant l’hypothèse de travail.

A negative or nonsignificant empirical correlation between aggregate R&D intensity and the economic growth rate is a well-known fact in the empirical growth literature, but scarcely addressed in the theoretical growth literature. This paper develops an endogenous-growth~model that explores the interrelation~between horizontal and vertical R&D under a lab-equipment specification that is consistent with that stylized fact. A key feature is that the growth rate is fully endogenous both on the intensive and on the extensive margin. Strong composition effects between horizontal and vertical R&D, along both transition and the balanced-growth path, then emerge as the main mechanism producing those results. This setting also allows us to obtain a relationship between economic growth and firm dynamics that is consistent with the empirical facts.

The analysis of inequality and polarization patterns between by regions of a national economy is central to ascertain their possibilities of future economic development. In this work we study such patterns in municipalities and boroughs of Mexico City Metropolitan Area (Zona Metropolitana de la Ciudad de Mexico, ZMCM). The evolution of inequality and polarization in this important area of Mexico is studied with new proposals of measurement using spatially conditioned indexes and through a dynamic transition analysis. The results confirm that the territorial inequality has grown among the municipalities and boroughs that integrate the ZMCM. Moreover, this phenomenon coincides with an increase of the polarization characterized by the formation of four subgroups or convergence clubs.

Literature is replete with both top–down and bottom–up energy policy models developed for addressing various policy and planning concerns in developed countries. These models provide a good starting point for analyzing certain issues in the modern industries of developing ...

We present a quantitative experimental evidence for the influence of critical fluctuations on the high frequency dielectric relaxation in a binary critical mixture. The analysis clearly shows the presence of critical anomaly both for the maxima (epsilon(")(p)) and frequencies (f(p)) of loss curves peaks. For the temperature evolution of epsilon(")(p) similar relation as for the static dielectric permittivity was obtained. The temperature dependence of relaxation times can be portrayed by using the Eyring-type equation remote from the critical consolute point and shows the unusual precritical speeding up. The obtained behavior resembles that found recently in the isotropic phase of nematic liquid crystals [A. Drozd-Rzoska and S. J. Rzoska, Phys. Rev. E 65, 041701 (2002)]. Results presented agree also with the recent theoretical suggestion [S. Goodyear and S. C. Tucker, J. Chem. Phys. 111, 9673 (1999)] that relaxation in supercritical fluids may exhibit glasslike features.

Mediterranean ecosystems are global hotspots of biodiversity threaten by human disturbances. Growing evidence indicates that regeneration of Mediterranean forests can be halted under certain circumstances and that successional stages can become notoriously persistent. The Mediterranean sclerophyllous forest in central Chile is been largely transformed into savannas dominated by the invasive legume tree Acacia caven as result of interacting management and ecological factors. We used multi-temporal satellite imag- ery to study the transition dynamics of these major vegetation types over the last four decades (1975– 2008). Vegetation changes were related to indicators of resource availability (topography, water avail- ability, solar radiance), potential propagule availability (distance to forest remnant patches) and distur- bance regimes (grazing, fire occurrence and distance to roads and cities). During this study period, forests were mostly converted into Acacia savannas (46.1%). Aca...

In the past 15 years sedimentological studies (Valentine and Giannetti, 1995; Wilson and Hildreth, 1997; Rosi et al., 2001), physical models (Neri et al., 1988; Veitch and Woods, 2000; Kaminski and Jaupart, 2001) and laboratory experiments (Carey et al., 1988) converge at defining a new eruptive regime transitional between the fully convective and the fully collapsing end -members. Buoyant columns and density currents are contemporaneously fed in the transitional dynamic regime and fall beds are intercalated with the density current deposits in the area invested by them. The sedimentological analysis of the well exposed 800yr B.P. plinian eruption of the volcano Quilotoa (Ecuador) enabled us to i) recognize a gradual evolution of the eruptive regime, ii) characterize the fall and density current deposits emplaced during the transitional regime. The eruptive activity began with at least two phreatic explosions and the effusion of a small volume lava dome. Eruptive behaviour then switched to explosive and fed a purely convective column that accumulated a reverse graded pumice fall while rising up to an height of 30 km. A small volume, diluted and slow density current (S1 current) was emplaced in the proximal SW sector just before the column reached its maximum height. Two group s of more voluminous and faster intra-plinian density currents (S2 and S3 currents) were subsequently emplaced contemporaneously with the accumulation of the lower and upper part respectively of a normal graded pumice fall bed. S2 and S3 currents were radially distributed around the crater and deposited bedded layers with facies of decreasing energy when moving away from the crater. Massive beds of small volume were emplaced only i) inside the proximal valley channel near the topography break in slope, ii) outside the valley channel in medial area where the currents impinged against relieves. A thick sequence of pyroclastic flow deposits (S4 currents) accumulated in the valley channels around the crater only in a post-plinian phase. During this phase, the convective plume was purely coignimbritic. The runout (from 4 to 11 km) and the degree of valley -confinement progressively increased from S1 to S4 currents. The eruption ended with the collapse of a 2.6 km summit caldera. During this last eruptive phase, coarse lithic-rich flow units with runout shorter than previously were emplaced. The parallel evolution of column height (grain-size), fountain height (size of ballistics) and flow properties (surges vs. flows) compares well with the numerical simulations of pyroclastic dispersion performed by Neri et al. (2002). In the whole dispersion area, the fall bed has a polymodal grain-size. The coarse modes of the fall appear related to the plinian column, while the fines ones have a co-ignimbrite fall origin. Sub-pop ulation analysis shows that the fine modes are related to ash aggregation that in transitional eruptions plays a significant role in the deposition of very fine sizzes also in very proximal areas. The fall deposit is totally eroded and reworked by the syn-plinian currents in the proximal areas and partially eroded in the medial areas. Grain-size and maximum clast analysis indicate that a significant fraction of the intraplinian beds is of primary fall origin. Strong similarities are found between the Quilot oa deposits and that accumulated during the transitional phase of the 1991 Pinatubo eruption (Rosi et al., 2001). These evidences should be carefully taken in account for risk assessment when analysing deposits accumulated in the transitional eruptive regi me with the aim at calculating the physical parameters characterizing the density currents ( Brissette and Lajoie, 1990). References : Brissette FP and Lajoie J (1990) Depositional mechanics of turbulent nuées ardentes (surges) from their grain-sizes. Bull Volcanol 53:60-66. Carey S, Sigurdsson H, Sparks RSJ (1988) Experimental studies of particle-laden plumes. J Geophys Res 93:15314-15328 Kaminski E and Jaupart C (2001) Marginal stability of atmospheric eruption columns and pyroclastic flow generation J Geophys Res 106: 21785-21798 Neri A, Papale P and Macedonio G (1998) The role of magma composition and water content in explosive eruptions: 2. Pyroclastic dispersion dynamics. J Volcanol Geotherm Res 87: 95-115 Neri A, Di Muro A, Rosi M (2002) Mass partition during collapsing and transitional columns by using numerical simulations. In press on J Volcanol Geotherm Res Rosi M., Paladio-Melosantos M.L., Di Muro A., Leoni R., Bacolcol T. (2001) Fall vs Flow Activity During the 1991 Climactic Eruption of Mt. Pinatubo (Philippines). Bull Volcanol 62: 549-566 Valentine G.A., Giannetti B. (1995) Single Pyroclastic beds deposited by simultaneous fallout and surge processes: Roccamonfina volcano, Italy. J Volcanol Geotherm Res 64:129-137. Veitch G and Woods A (2002) Particle recycling and oscillations of volcanic eruption columns. J of Geophys Res, 105: 2829-2842. Wilson C.J.N., Hildreth W. (1997) The Bishop Tuff: new insights from eruptive stratigraphy J of Geol. 105:407-439.