Das ökonometrische Modell des HWWA-Instituts zur Konjunkturprognose

Zur Konjunkturprognose werden oft auch ökonometrische Modelle eingesetzt. Schärft die Anwendung EDV-gestützter ökonometrischer Verfahren den Blick in die Zukunft oder führt die vermeintliche „Exaktheit" solcher Modelle eher zu einer Verengung des Blickwinkels? Welche Probleme ergeben sich beim Aufbau gesamtwirtschaftlicher Modelle und bei ihrer Verwendung für Konjunkturprognosen? Diesen Fragen wird anhand des gesamtwirtschaftlichen Modells des HWWA nachgegangen. --

Development of zero-order release tablets

A thesis submitted to the Faculty of Health Sciences, University of the Witwatersrand, in fulfilment of the requirements for the degree of Doctor of Philosophy Johannesburg, 1996A new core-in-cup tablet manufactured from a novel adjustable punch, has been formulated and evaluated as to its ability to release various model drugs via a zero-order rate of release. The new punch, with an inner adjustable rod that can be adjusted to produce cup-shaped tablets of various thicknesses, was used to manufacture the core-in-cup tablets. These core-in-cup tablets were then evaluated as to their ability to be manufactured on a tabletting press, and to their ability to release model drugs both in vitro and in vivo. After evaluating the effect of various formulation factors on the compressibility and flow of various directly compressible powder combinations via factorial design, a directly compressible combination of 10%w/w camauba wax in ethylcellulose was found to produce the best cup tablets for the core-in-cup tabletsIT201

Emerging masculinities: a qualitative analysis of the construction and practice of adolescent masculinities.

Masters Degree. University of KwaZulu-Natal, Pietermaritzburg.This study aimed to investigate how a sample of South African adolescent boys construct and negotiate their masculine identities from the different versions of being male available to them within their particular social and cultural contexts. This study employed a qualitative research design using the semi-structured interview protocol developed by Frosh et al.(2002). The results of this research consistently reveal that masculinity among adolescent boys is dynamic, multiple and continually being made, performed, resisted and contested. The subjects described different ways of being male, often having to negotiate a coherent masculine identity from many competing, often contradictory versions of masculinity. However hegemonic or 'hard' masculinity remains the dominant standard against which other ways of being male are evaluated. These masculinity constructions show remarkable similarities to those of the English adolescent boys in the Frosh, Phoenix and Pattman (2002) study, which suggests that the hegemonic ideal is particularly wide ranging and well-entrenched in the lives of boys

Charge Transport Transitions and Scaling in Disordered Arrays of Metallic Dots

We examine the charge transport through disordered arrays of metallic dots using numerical simulations. We find power law scaling in the current-voltage curves for arrays containing no voids, while for void-filled arrays charge bottlenecks form and a single scaling is absent, in agreement with recent experiments. In the void-free case we also show that the scaling exponent depends on the effective dimensionality of the system. For increasing applied drives we find a transition from 2D disordered filamentary flow near threshold to a 1D smectic flow which can be identified experimentally using characteristics in the transport curves and conduction noise.Comment: 4 pages, 4 postscript figure

The convection-diffusion equation for a finite domain with time varying boundaries

A solution is developed for a convection-diffusion equation describing chemical transport with sorption, decay, and production. The problem is formulated in a finite domain where the appropriate conservation law yields Robin conditions at the ends. When the input concentration is arbitrary, the problem is underdetermined because of an unknown exit concentration. We resolve this by defining the exit concentration as a solution to a similar diffusion equation which satisfies a Dirichlet condition at the left end of the half line. This problem does not appear to have been solved in the literature, and the resulting representation should be useful for problems of practical interest. Authors of previous works on problems of this type have eliminated the unknown exit concentration by assuming a continuous concentration at the outflow boundary. This yields a well-posed problem by forcing a homogeneous Neumann exit, widely known as the Danckwerts [1] condition. We provide a solution to the Neumann problem and use it to produce an estimate which demonstrates that the Danckwerts condition implies a zero concentration at the outflow boundary, even for a long flow domain and a large time.Comment: W. J. Golz and J. R. Dorroh. 2001. The Convection-diffusion equation for a finite domain with time varying boundaries. Applied Mathematics Letters 14 : 983-988 (received by AML September 2000; accepted by AML October 2000

Mixing in a fluid flowing through a packed bed

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1948.Includes bibliographical references (leaf 68).by P.V. Danckwerts, A.C. Sugden.M.S

Physical patterns and post-hoc measures of wildfire behaviour in grassland

Botany and Zoolog

Water footprint and economic water productivity of citrus production: a comparison across three river valleys in the Eastern Cape Milands

South Africa is a semi-arid, water scarce country. The nation has suffered a spate of severe droughts in several regions in recent years, which have significantly impacted the country’s economy. Global warming, population growth, and rising demand for water intensive products are only expected to intensify water supply problems in the future. The agricultural industry is the largest consumer of water in South Africa, accounting for the majority of total surface water withdrawals. As such, the agricultural sector is faced with complex and difficult management decisions in the face of a potential water supply crisis. The water footprint (WF) and economic water productivity (EWP) of citrus production across three river catchments located in the Eastern Cape Midlands (situated in the vicinity of the settlements of Adelaide, Cookhouse and Fort Beaufort respectively) were calculated and compared. In the long-term average (LTA), blue WF weighted across all three regions accounted for the greatest proportion of total WF (53%), followed in turn by green and grey WF (30% and 17% respectively). LTA blue and grey WF was lowest in the Adelaide region, while green WF was smallest in the Fort Beaufort region. Blue, green and grey WF were found to be greatest in the Cookhouse region. LTA EWP was greatest in the Fort Beaufort region and smallest in the Adelaide region. Of all variety groups assessed, lemons were found to have the lowest LTA crop water use and blue, green and grey WF when considering citrus production averaged across all three study regions. Satsumas has the second smallest LTA blue, green and grey WF, followed by navels, mid-season mandarins, and finally, late mandarins. Lemons had the greatest LTA EWP of all varieties, followed in turn by satsumas, late mandarins, mid-season mandarins and navels. Blue crop water use was consistently lowest in the designated wet year and highest in the dry year. However, this same trend was not necessarily true for WF findings. WF and EWP are useful indicators of water use which can be used to help guide complex water management decisions. However, these indicators are single-factor productivity measures applied in a multi-factor environment. It is therefore important that factors outside of water use are considered when making water management decisions. Moreover, it is important to examine the impact that the various components making up WF and EWP have on the resultant figures, rather than merely considering the superficial results themselves. Factors such as CWU, orchard maturity, crop choice, potential yield, climate, irrigation system, economic return, water allocation and water availability should all be taken into account