"The Look of Stagniation: Romania's Erratic Transition"

A transition path is expected to lead, eventually, to economic performance and sectoral structure typical of market economies. This twofold result would issue from a complex resource re-allocation process, almost automatically igniting a new mechanism of accumulation and growth. Romania's experience of persistent fluctuations around a descending trend, however, seems to contradict such notion of the one-way, self-fuelling path. It causes us to rethink some of the analytical tools and theories economists are using everyday. In this paper, I will offer the reflections of an academician together with, hopefully, some more practical suggestions. My main point is that an analysis focusing solely upon resource re-allocation mechanisms cannot fully account for Romania's erratic transition because it tends to miss the link with the dual processes of accumulation and creation of new resources. I will, therefore, reconstruct the "other side" of Romania's story by looking at its dynamic structure, described by the distribution of the economy's sectoral paths. The evolution over time of such distribution is the key to understanding the two issues of macroeconomic vulnerability and the non-sustainability of the country's current situation. Thus, the dynamics of Romania's economy is treated as a specimen of an independent variety of transition. It is one that not only proves unable to initialise and then sustain long-term growth; it seems to actually absorb and destroy more resources than it creates, in this way generating a slow agony from time to time interrupted sudden bursts of activity. The term dynamic trap is meant to describe such a repeating pattern of wild fluctuations around a contracting trend. Due partly to the short time horizon and data availability, the conclusions of the foregoing analysis can only be tentative. Still, they clearly point out the need to re-consider policy for Romania and similar countries. In particular, measures are required to put in place and to enhance mechanisms of technology transfers, to re-orient sectoral composition that generates trade specialization, and generally to create conditions for an accelerated process of accumulation of physical as well as human capital assets. The economic environment in such countries seems unable to process macroeconomic policies in the expected way.

Pathologic Hematopoiesis: Congenital dyserythropoietic anemia Type II, congenital erythrocytosis anf thrombocytopenias

The blood contains several different types of cells. Each of these cell types is quite distinct in appearance, and each has a specific biological function. Despite their extreme structural and functional differences, blood cells are the progeny of a single type of cell: the hematopoietic stem cell (HSC). The processes involved in the production of the various cell types of the blood from the HSCs are collectively called hematopoiesis. Hematopoiesis includes HSC self-renewal, HSC commitment to specific lineages, and maturation of lineage-committed progenitors into functional blood cells. Self-renewal may occur by symmetric HSC division, such as expansion of the HSC pool during fetal life or post-HSC transplantation. Other possible fates of HSC divisions include apoptosis or mobilization to the peripheral circulation following stress such as growth factor stimulation or depletion of marrow cells by irradiation or chemotherapy. During normal steady state conditions, HSCs reside mainly in the marrow cavity, but under certain stress conditions HSCs can migrate and colonize other organs like liver and spleen in a process termed extramedullary hematopoiesis. Hematopoiesis begins early during embryogenesis and undergoes many changes during fetal and neonatal development. Unlike some organ systems that form in early life and are not continually replaced, turnover and replenishment of the hematopoietic system continue throughout life

Analysis and comparison of microscopic traffic flow models with real traffic microscopic data

The ever more widespread use of microscopic traffic simulation in the analysis of road systems has re-focussed attention on sub-models, including car-following models. The difficulties of micro-simulation models in accurately reproducing real traffic phenomena stem not only from the complexity of calibration and validation operations but also from the structural inadequacy of the sub-models themselves. These drawbacks both originate in the scant information available on real phenomena, due to the difficulty of gathering accurate field data. In this study, the use of K-dGPS instruments allowed trajectories of four vehicles in a platoon to be accurately monitored in real traffic conditions, both on urban and extra-urban roads. Some of these data were used to analyse the behaviour of four microscopic traffic flow models which differed greatly both in approach and complexity. The effect on model calibration results of the choice of performance measures was first investigated and inter-vehicle spacing was shown to be the most reliable measure. Model calibrations showed results similar to those obtained in other studies that used test track data. Instead, validations resulted in higher deviations compared to previous studies (with peaks in cross-validations between urban and extra-urban experiments). This confirms the need for real traffic data. On comparison, all the models showed similar performances (i.e. similar deviations in validation). However, if surprisingly the simplest model performed on average better than the others, the most complex one was the most robust, never reaching particularly high deviations

Dynamic Complementarities, Efficiency and Nash Equilibria for Populations of Firms and Workers

We consider an economy with two types of firms (innovative and non-innovative) and two types of workers (skilled and unskilled), where workers' decisions are driven by imitative behavior, and thus the evolution of such an economy depends on the initial distribution of the firms. We show that there exists a continuous of high level steady states and only one low level and asymptotically stable equilibrium. There exists a threshold value on the initial number of firms to be overcome it to located in the basin of attraction of one of the high level equilibrium. We show that in each high level equilibrium there coexists a share of innovative firms with a share of non-innovative firms, and a share of skilled workers (human capital) coexisting with a share of unskilled workers. But if the initial share of innovative firms is lower than the threshold value, then the economy evolves to a low level equilibrium wholly composed by non-innovative firms and unskilled workers. Finally, we characterise the equilibria as the evolutionarily stable strategies against a field.Imitative Behavior, Poverty Traps, Strategic Complementarities, Two Population Normal Form Game, Threshold Value.

On the asymptotic behaviour of solutions to the fractional porous medium equation with variable density

We are concerned with the long time behaviour of solutions to the fractional porous medium equation with a variable spatial density. We prove that if the density decays slowly at infinity, then the solution approaches the Barenblatt-type solution of a proper singular fractional problem. If, on the contrary, the density decays rapidly at infinity, we show that the minimal solution multiplied by a suitable power of the time variable converges to the minimal solution of a certain fractional sublinear elliptic equation.Comment: To appear in DCDS-

Global existence for reaction-diffusion evolution equations driven by the p-Laplacian on manifolds

We consider reaction-diffusion equations driven by the p-Laplacian on noncompact, infinite volume manifolds assumed to support the Sobolev inequality and, in some cases, to have L2 spectrum bounded away from zero, the main example we have in mind being the hyperbolic space of any dimension. It is shown that, under appropriate conditions on the parameters involved and smallness conditions on the initial data, global in time solutions exist and suitable smoothing effects, namely explicit bounds on the L∞ norm of solutions at all positive times, in terms of Lq norms of the data. The geometric setting discussed here requires significant modifications w.r.t. the Euclidean strategies

On the stability of solutions of semilinear elliptic equations with Robin boundary conditions on Riemannian manifolds

We investigate existence and nonexistence of stationary stable nonconstant solutions, i.e. patterns, of semilinear parabolic problems in bounded domains of Riemannian manifolds satisfying Robin boundary conditions. These problems arise in several models in applications, in particular in Mathematical Biology. We point out the role both of the nonlinearity and of geometric objects such as the Ricci curvature of the manifold, the second fundamental form of the boundary of the domain and its mean curvature. Special attention is devoted to surfaces of revolution and to spherically symmetric manifolds, where we prove refined results

Use of tactile cues by Notiosorex crawfordi (Insectivora) in response to topographical features in the environment

Abstract: The present studies were conducted on the ability of males of the gray shrew, Notiosorex crawfordi to use tactile cues to detect and respond to changes in topographical features of their environment. The animals were videotaped, digitized, and analyzed through video recordings. All subjects showed habituation (decrease in distance traveled) to arena conditions, followed by dishabituation when positions of the blocks were changed. Intact (INT) and sham controls (SHC) shrews traveled significantly greater distances and showed higher exploration velocities as compared to animals with shaved vibrissae (SHV). Results provide empirical evidence that N. crawfordi can effectively use tactile cues to detect and respond to changes in its environment