Measuring the gravitational field in General Relativity: From deviation equations and the gravitational compass to relativistic clock gradiometry

How does one measure the gravitational field? We give explicit answers to this fundamental question and show how all components of the curvature tensor, which represents the gravitational field in Einstein's theory of General Relativity, can be obtained by means of two different methods. The first method relies on the measuring the accelerations of a suitably prepared set of test bodies relative to the observer. The second methods utilizes a set of suitably prepared clocks. The methods discussed here form the basis of relativistic (clock) gradiometry and are of direct operational relevance for applications in geodesy.Comment: To appear in "Relativistic Geodesy: Foundations and Application", D. Puetzfeld et. al. (eds.), Fundamental Theories of Physics, Springer 2018, 52 pages, in print. arXiv admin note: text overlap with arXiv:1804.11106, arXiv:1511.08465, arXiv:1805.1067

Damping and absorption of high frequency waves in dusty plasmas

By employing standard statistical techniques of linear fluctuation theory, it is shown how the ensemble averages over statistical distributions of charged massive grains in a dusty plasma can result in "average" dispersion relations for high‐frequency electromagnetic and electrostatic waves. The dispersion relations admit solutions for complex frequencies and wave numbers, suggesting that the waves can be damped (Im ω≠0) or absorbed (Im k≠0) in a dusty plasma

The ultimate challenge or just common sense : The present practices and future opportunities to increase the utilization of livestock manure as organic fertilizer in North West Russia

The ultimate challenge or just common sense The present practices and future opportunities to increase the utilization of livestock manure as organic fertilizer in North West Russia The risk of nutrient contamination of surface- and groundwater’s from livestock farming has been one of the issues to address in international cooperation initiatives in the Baltic Sea Region during the recent decade. In particular, international initiatives targeting North West Russia in the 2000-2010’s by HELCOM and NEFCO and as bilateral cooperation with Russia by Finland and Sweden have assessed the severity of the threat, have introduced technical solutions to process livestock manure and have explored the market potential for fertilizer products made through processing of livestock manure. However, a comprehensive resolution to the growing problem still remains a long term goal and many of the barriers to increase manure processing and organic fertilization – poor economic incentives and lack of proven cost-efficient technologies – still prevail. In Russia, ongoing adaptation of state support to agriculture as part of the WTO membership brings about indirect area-based farm support and increased share of support to investments in farm infrastructure, rural development and in management of health, hygienic and environmental aspects. These represent positive opportunities for increasing sustainable manure management and the proportion of manure-based fertilization. The Technological Regulations (TR) instrument introduced in 2008, enhanced enforcement and systematic introduction of BAT in Russian agriculture, provide a set of management tools which has good potential to be effective for the administration and be accepted by the agricultural companies. At the same time, there is a risk that the increasing concentration of livestock, in particular poultry production in Leningrad Oblast narrows alternative paths for sustainable manure management and is leading to a situation in which only large scale technological solutions may prove to be viable in order to solve the issue on the regional scale. This report reviews the current environment in North West Russian Federation to advance sustainable animal manure management and reflects this against the EU context with related examples from Latvia. The report concludes that a sustainable future for North West Russian agriculture relies on the overall sustainability of the enterprises and that regulative and subsidy measures should reinforce the positive link between economic and environmental benefit. Spatial aspects on the territorial level should be addressed as the location of agricultural enterprises both relative to each other and relative to human settlements have increasing importance from the perspective of environmental, health and biosecurity implications. Thirdly, Russia’s adaptation to the WTO framework, the process of implementing BAT in agriculture and the TR instrument to support holistic farm specific solutions provide a range of interesting topics for future international cooperation on both technical and policy levels