Agricultural Growth in China and Sub-Saharan African Countries

Agriculture remains a dominant sector in the economies of most African and several Asian countries. However, the poor performance of agriculture in Africa stands in sharp contrast to the robust agricultural growth in many Asian countries.2 In this regard, the experience of China is perhaps as impressive as it is relevant to many countries in Sub-Saharan Africa. A general observation is that the productivity of land and labour has to rise through intensive agriculture, given the limited area of arable land (in China and Africa) and the high rates of growth of population (as in Africa). In many African countries, labour productivity has fallen and land productivity has not increased significantly. In China, productivities of both land and labour have increased significantly since at least the early 1980s. Agricultural output can increase in three ways: (i) get more from the same quantities of inputs through better utilisation of the existing capacity; (ii) use increased quantities of inputs; and (iii) use new techniques to raise the productivity of each input or raise the total product curve. All of these may require changes in tenurial arrangements, levels of investment in infrastructure and support services, and policies that affect the prices of outputs and inputs. A close examination of factors underlying the contrasting experiences in China and African countries reveals important differences in the institutional and policy environments affecting the individual behaviour with regard to the adoption and use of new (profitable) technologies to raise the land and labour productivities.

Gravitational Wave Driven Mergers and Coalescence Time of Supermassive Black Holes

The evolution of Supermassive Black Holes (SMBHs) initially embedded in the centres of merging galaxies realised with a stellar mass function (SMF) is studied from the onset of galaxy mergers till coalescence. We performed a large set of direct N-body simulations with three different slopes of the central stellar cusp and different random seeds. Post Newtonian terms up to order 3.5 are used to drive the SMBH binary evolution in the relativistic regime. The impact of a SMF on the hardening rate and the coalescence time is investigated. We find that SMBH binaries coalesce well within one billion years when our models are scaled to galaxies with a steep cusp at low redshift. Here higher central densities provide larger supply of stars to efficiently extract energy from the SMBH binary orbit and shrink it to the phase where gravitational wave (GW) emission becomes dominant leading to the coalescence of the SMBHs. Mergers of models with shallow cusps that are representative for giant elliptical galaxies having central cores result in less efficient extraction of binary orbital energy due to the lower stellar densities in the centre. However, high values of eccentricity witnessed for SMBH binaries in such galaxy mergers ensure that the GW emission dominated phase sets in earlier at larger values of the semi-major axis. This helps to compensate for the less efficient energy extraction during the phase dominated by stellar encounters resulting in mergers of SMBHs in about one Gyr after the formation of the binary. Additionally, we witness mass segregation in the merger remnant resulting in enhanced SMBH binary hardening rates. We show that at least the final phase of the merger in cuspy low mass galaxies would be observable with the GW detector eLISA.Comment: Accepted for publication in Astronomy & Astrophysic

Experimental and Theoretical Analysis of Soft Magnetic Materials for Power applications

The efficiency of electrical machines carries a global impact because they fulfill about three-quarters of global electrical energy consumption. Its improvement requires a sound knowledge of energy loss properties of magnetic materials used in the core of electrical machines, especially non-conventional supply conditions, such as non-sinusoidal, high induction, alternating (1-D) and rotating (2-D) flux waveforms that have been posed with the incorporation of new electronic devices and materials in the systems. For these reasons, novel theoretical models and experimental techniques need to be developed to obtain the loss behavior under these complex flux regimes. To address these issues, experimental investigation and theoretical analysis have been carried out in this thesis on different magnetic materials and a wide ensemble of supply conditions. The aim of the theoretical analysis was to fill the gap between the physicists and the engineers by developing simple models that can be applied to compute the loss under realistic supply conditions. This theoretical frame is rooted in the physical principle of the separation of loss and the Statistical Theory of Loss (STL) by which the loss can be separated into the hysteresis, classical, and excess components. The concept of loss separation has been exploited under 1-D flux and extended to 2-D fluxes, where the relations between alternating and rotational losses have been obtained on a number of different materials, this analysis restricted to the region not influenced by skin effect. The proposed theoretical models have been tested by comparing loss figure of different magnetic materials over a wide range of frequencies, induction levels, and conventional or non-conventional supply conditions. To this purpose, loss characterization of non-oriented Fe-(3.2wt \%)Si steels have been performed using a three phase magnetizer able to generate 1-D and 2-D flux patterns, up to saturation magnetization. Fieldmetric and Thermometric methods have been applied at low and very high induction levels. Loss characterization of other non-oriented Fe-Si and low carbon steels have also been performed under 1-D flux at very low and high sinusoidal inductions using Epstein frame, single sheet tester or ring samples, over frequencies ranging from quasi-static conditions up to 10 kHz. Systematic uncertainties have been observed in measurements using a Single Sheet Tester due to MMF drop in flux closing yoke and a compensated Permeameter has been designed to reduce these uncertainties by compensating the MMF drop in the flux closing yoke

Socio-Economic Indicators in Rural Pakistan: Some Evidence

This study attempts to quantify the inter-provincial and interdistrict differences among villages with respect to the availability of and access to certain crucial inputs and services which affect the level of living and even quality of life in rural areas.. Using the taxonomic method for rank ordering and clustering of regions, this comparative analysis should help in identifying the areas (provinces or districts) and activities (or services) in each area which may require immediate or special attention of policy makers and planners.

Monetary aggregates in Pakistan: theoretical and empirical underpinnings

The objective of this study is to analyze theoretical as well as empirical soundness of the current monetary aggregates (M2) and to propose a broader monetary aggregate (M3), by exploring the functional characteristics and empirical relevance of financial assets. We used annual time series data from FY76 to FY03 and employed both the functional and empirical (F-M dual criteria) approaches. The results indicate that current monetary aggregates seemed to have been defined more on functional considerations compared to the empirical evidence. The analysis of new set of financial assets suggests that, while the various savings schemes individually as well as in aggregate were able to meet F-M dual criteria, deposits of NBFIs failed to satisfy this criteria. However, the functional considerations suggest that these deposits should, nevertheless, be included in a broader definition of monetary aggregates (M3).Monetary Aggregates, Pakistan