Agro-Ecological Assessment for the Transition of the Agricultural Sector in Ukraine. Part I: Socio-Economic Aspects

Since 1991, Ukraine has been undergoing a transformation of its economic and social system to enable the transition to a market economy. There are a number of positive developments that have already resulted from the changes in the socio-economic environment. However the transformation of farming systems into new forms did not greatly improve the sustainable use of natural resources or strengthen the economic performance, so that the influence of this intervention on sustainability of farming systems in Ukraine has had more negative than positive results. Large-scale farms continue to over-exploit natural resources and new private farmers, lacking in experience, knowledge and financial resources, continue to use obsolete technologies that are economically inefficient and may cause land degradation. All the components of the farming sector such as agricultural enterprises, household plots, and individual private farms, still remain problematic in terms of efficiency and are constrained by policies and inadequate markets. While economic conditions for agriculture have changed considerably since the beginning of the 1990s, agricultural policy in Ukraine was focused on trying to revive the production level, without the comprehensive analysis of agro-ecological conditions, internal and external markets, infrastructure, farmers' incentives etc. Rational agricultural land use is imperative in Ukraine. Existing agricultural systems are not appropriate for changing production, technological, economic or ecological realities. There is an urgent need for major policy changes in Ukraine towards rural welfare growth, sustainable agriculture and efficient land management, and establishment of agricultural market networks supported by adequate legislation. With the additional pressure of transition to a market economy, a new agricultural paradigm is required. This paper is the first in a series of reports on "Agro-ecological Assessment for Transition of the Agricultural Sector in Ukraine". The reports aim at further elaboration of integrated strategies and policies towards maintaining the sustainability of natural resources and the environment while remaining economically viable and internationally competitive. This paper on "Socio-economic analysis" describes the main socio-economic features of the transition processes in the Ukrainian agricultural sector, trends in agricultural production, and changes in its farming systems and land use. The second report "Land Resources and Agricultural Productivity: Methodology and Results" provides the inventory of natural (land, climatic) resources and the evaluation of biophysical limitations and potentials of the crop production in Ukraine at the national and regional levels. The third paper "Climate Change Impacts on Agricultural Productivity: Methodology and Results" investigates impacts of climate change/variability on the crop production and land use change in Ukraine on national and regional scales and indicates possible ways of adaptation over the coming three decades

2D materials and van der Waals heterostructures

The physics of two-dimensional (2D) materials and heterostructures based on such crystals has been developing extremely fast. With new 2D materials, truly 2D physics has started to appear (e.g. absence of long-range order, 2D excitons, commensurate-incommensurate transition, etc). Novel heterostructure devices are also starting to appear - tunneling transistors, resonant tunneling diodes, light emitting diodes, etc. Composed from individual 2D crystals, such devices utilize the properties of those crystals to create functionalities that are not accessible to us in other heterostructures. We review the properties of novel 2D crystals and how their properties are used in new heterostructure devices

Lifting of the Landau level degeneracy in graphene devices in a tilted magnetic field

We report on transport and capacitance measurements of graphene devices in magnetic fields up to 30 T. In both techniques, we observe the full splitting of Landau levels and we employ tilted field experiments to address the origin of the observed broken symmetry states. In the lowest energy level, the spin degeneracy is removed at filling factors $\nu=\pm1$ and we observe an enhanced energy gap. In the higher levels, the valley degeneracy is removed at odd filling factors while spin polarized states are formed at even $\nu$. Although the observation of odd filling factors in the higher levels points towards the spontaneous origin of the splitting, we find that the main contribution to the gap at $\nu= -4,-8$, and $-12$ is due to the Zeeman energy.Comment: 5 pages, 4 figure

Diagrammatic Quantum Monte Carlo for Two-Body Problem: Exciton

We present a novel method for precise numerical solution of the irreducible two-body problem and apply it to excitons in solids. The approach is based on the Monte Carlo simulation of the two-body Green function specified by Feynman's diagrammatic expansion. Our method does not rely on the specific form of the electron and hole dispersion laws and is valid for any attractive electron-hole potential. We establish limits of validity of the Wannier (large radius) and Frenkel (small radius) approximations, present accurate data for the intermediate radius excitons, and give evidence for the charge transfer nature of the monopolar exciton in mixed valence materials.Comment: 4 pages, 5 figure

Determination of Different Biological Factors on the Base of Dried Blood Spot Technology

It is well-known that distinct biological indices (analytes) have distinct variability. We try to use some mathematical algorithms to pick out a set of blood parameters which give an opportunity to retrieve the initial volume of the blood spotted, and use it to calculate exact concentrations of analyts interesting to a physician. For our analysis we used the database of biochemical blood parameters obtained in Russian Scientific Center of Roentgen-Radiology during 1995-2000, which includes more than 30000 of patients.Comment: 5 page