On the extended states in the Quantum Hall regime and in zero magnetic field

For a two dimensional electron system in a strong perpendicular magnetic field B, there are extended states at each Landau level. We show that if the inverse compressibility is negative, then the extended states float downward in energy when B decreases. We set up a condition for the case where all extended states are below the fermi energy in the low B limit. The condition may explain why a conducting state has been observed in a high mobility Si-Mosfet but so far not in high mobility n-GaAs.Comment: 6 pages, postscript only, contribution to SemiMag 1

How important is the efficiency of government investment ? The case of the Republic of Congo

The Republic of Congo, an oil rich country in Central Africa, has made substantial progress in the past decade in stabilizing the economy and achieving high growth rates. However, despite reaching middle-income country status in 2006, the economy is not diversified, poverty remains pervasive, and social indicators are well below the average for countries with a similar income level. This paper analyzes aspects of an ambitious investment program on which the government has embarked to improve the provision of basic services and promote private sector development. The success of this program, however, is questionable given the low absorptive capacity of the country and in particular the poor efficiency of public investment management. The analysis is based on simulations with an economy-wide model for analysis of development strategies and government policies, MAMS (Maquette for MDG Simulations). The results of the simulations show that slightly delaying large investment projects, while simultaneously improving the efficiency of the investment program, would lead to significantly higher growth rates and lower poverty levels. The analysis therefore confirms the importance of efficient public investment management for the optimal use of the country's resources.Economic Theory&Research,Labor Policies,Debt Markets,Access to Finance,Non Bank Financial Institutions

Leaf stripe resistance of spring barley cultivars

Results of six years of screening trials clearly indicate that effective resistance against barley leaf stripe is available, also in modern cultivars. Among the spring barley cultivars that are currently most widely grown in Denmark, Cabaret, Troon, Sebastian, Justina and Brazil appear most resistant, but only Brazil combines a favourable resistance performance (= low mean and standard deviation of environment-adjusted leaf stripe incidence) with a high number of observations (= years of testing). However, the cultivars appearing most resistant over the years are relatively old ones such as Vada, Alabama, Odin and particularly Scarlett, which has been resistant in all years in which it was tested. Amongst the new cultivars, Marigold, Native and SW Immer appear to have the most promising resistance properties so far. However, they have only been tested in two years of which only one had reasonably high infection levels. The results furthermore indicate huge year-to-year variation in infection levels, presumably due to variation in environmental conditions related to leaf stripe infection

Analyzing I(2) Systems by Transformed Vector Autoregressions

We characterize the restrictions imposed by the minimal I(2)-to-I(1) transformation that underlies much applied work, e.g. on money demand relationships or open-economy pricing relationships. The relationship between the parameters of the original I(2) vector autoregression, including the coefficients of polynomially cointegrating relationships, and the transformed I(1) model is characterized. We discuss estimation of the transformed model subject to restrictions as well as the more commonly used approach of unrestricted reduced rank regression. Only a minor loss of efficiency is incurred by ignoring the restrictions in the empirical example and a simulation study. A properly transformed vector autoregression thus provides a practical and effective means for inference on the parameters of the I(2) model.cointegration; stochastic trend; price homogeneity; nominal; real; Monte Carlo experiment

Scaling up aid or scaling down : the global economic crisis and Rwanda's MDGs

Rwanda is not on track to achieve most of the Millennium Development Goals at a time when hopes for scaled-up aid are mixed with concerns that, in the context of the global economic crisis, aid instead will be scaled down. This paper analyzes the effects of alternative scenarios for grant aid, government spending allocations (between infrastructure, agriculture, and human development), and government efficiency. The authors use an economy-wide model for development strategy analysis, Maquette for Millennium Development Goal Simulations. Under a plausible scenario for increased aid, annual growth in gross domestic product increases by as much as 0.6 percentage points relative to a baseline with a growth rate of 6 percent; by 2020, the headcount poverty rate declines to 32 percent, 3 percentage points lower than for the baseline. A plausible scenario for reduced aid leads to a symmetric growth reduction but a more pronounced increase in poverty, at 40 percent in 2020. When aid increases, the most positive growth and poverty reduction impacts occur if spending increases are allocated to infrastructure and agriculture; progress in human health and education is significant but weaker than if additional spending is focused on these areas. Given synergies and diminishing marginal returns from expansion in a limited area, the scenarios that may appear most attractive and politically feasible have a broad and balanced expansion across government functions, promoting both growth and human development.Population Policies,Economic Theory&Research,,Debt Markets,Achieving Shared Growth

Average fidelity between random quantum states

We analyze mean fidelity between random density matrices of size N, generated with respect to various probability measures in the space of mixed quantum states: Hilbert-Schmidt measure, Bures (statistical) measure, the measures induced by partial trace and the natural measure on the space of pure states. In certain cases explicit probability distributions for fidelity are derived. Results obtained may be used to gauge the quality of quantum information processing schemes.Comment: 15 revtex pages with 4 figures; Ver. 2: another distribution derived, an extra figure included, Ver. 3: comments in introduction and conclusion added ver 4. minor improvment

Individual plant care in cropping systems

Individual plant care cropping systems, embodied in precision farming, may lead to new opportunities in agricultural crop management. The objective of the project was to provide high accuracy seed position mapping of a field of sugar beet. An RTK GPS was retrofitted on to a precision seeder to map the seeds as they were planted. The average error between the seed map and the actual plant map was about 32 mm to 59 mm. The results showed that the overall accuracy of the estimated plant positions is acceptable for the guidance of vehicles and implements. For subsequent individual plant care, the deviations were not, in all cases, small enough to ensure accurate individual plant targeting