An empirical note on factor shares

In this study, we propose an explanation for why labor and capital shares do not seem to have a trend: an increasing trend in physical capital share is compensated by a decreasing trend in land share. Similarly, an increasing trend in human capital share is compensated by a decreasing trend in raw labor share. We also find empirical support for the claim that the elasticity of output with respect to reproducible factors, human and physical capital, is positively correlated with the income level. This result has important implications for economic growth theory and for empirical exercises related to economic growth

Analytical solutions for protective filters based on soil-retention and permeability criteria with respect to the phenomenon of soil boiling

For the successful performance of a granular filter medium, existing design guidelines, which are based on the particle size distribution (PSD) characteristics of the base soil and filter medium, require two contradictory conditions to be satisfied, viz., soil retention and permeability. In spite of the wider applicability of these guidelines, it is well recognized that (i) they are applicable to a particular range of soils tested in the laboratory, (ii) the design procedures do not include performance-based selection criteria, and (iii) there are no means to establish the sensitivity of the important variables influencing performance. In the present work, analytical solutions are developed to obtain a factor of safety with respect to soil-retention and permeability criteria for a base soil - filter medium system subjected to a soil boiling condition. The proposed analytical solutions take into consideration relevant geotechnical properties such as void ratio, permeability, dry unit weight, effective friction angle, shape and size of soil particles, seepage discharge, and existing hydraulic gradient. The solution is validated through example applications and experimental results, and it is established that it can be used successfully in the selection as well as design of granular filters and can be applied to all types of base soils.

Biased technological change, human capital and factor shares

We propose a one-good model where technological change is factor saving and costly. We consider a production function with two reproducible factors: physical capital and human capital, and one not reproducible factor. The main predictions of the model are the following: (a) The elasticity of output with respect to the reproducible factors depends on the factor abundance of the economies. (b) The income share of reproducible factors increases with the stage of development. (c) Depending on the initial conditions, in some economies the production function converges to AK, while in other economies long-run growth is zero. (d) The share of human factors (raw labor and human capital) converges to a positive number lower than one. Along the transition it may decrease, increase or remain constant.

Factor saving innovations and factor income shares

We present an endogenous growth model where innovations are factor saving. Technologies can be changed paying a cost and technological change takes place only if the benefits are larger than the costs. Since the gains derived from factor saving innovations depend on factor abundance, biased innovations respond to changes in factors supply. Therefore, as an economy becomes more capital abundant agents try to use capital more intensively. Consequently, (a) the elasticity of output with respect to reproducible factors depends on the capital abundance of the economy and (b) the income share of reproducible factors increases as the economy grows. Another insight of the model is that in some economies the production function converges to an AK in the long run, while in others long-run growth is zero

Re-measuring labor's share

Measuring labor's share of an economy's aggregate income seems straightforward, at least in principle. Count up wage and salary income, along with the value of benefits provided to employees, and divide it by total income. However, one fundamental concept of labor's share in macroeconomic theory is not the amount of aggregate income paid out to labor. Rather, it is the share of aggregate production that is attributable to "raw" units of labor. Or, otherwise stated, it is the share of aggregate income that would have been paid to laborers if they had no accumulated stocks of human capital.1 This share corresponds to an aggregate production function parameter: the elasticity of output with respect to physical (i.e. non-augmented or raw) units of labor (Robert Solow, 1957). In this paper we estimate annual raw labor’s share for the US, 1949 to 1996.

Practical stability with respect to model mismatch of approximate discrete-time output feedback control

This paper establishes a practical stability result for discrete-time output feedback control involving mismatch between the exact system to be stabilised and the approximating system used to design the controller. The practical stability is in the sense of an asymptotic bound on the amount of error bias introduced by the model approximation, and is established using local consistency properties of the systems. Importantly, the practical stability established here does not require the approximating system to be of the same model type as the exact system. Examples are presented to illustrate the nature of our practical stability result.

The effect of heating temperature on the properties of vermiculites from Tanzania with respect to potential agronomic applications

This study was carried out to assess the properties of vermiculites from Tanzania with respect to the temperature used to expand them. Vermiculites from five locations in the Mozambique Belt of Tanzania were sampled and heated at 15, 200, 400, 600 and 800 °C in a muffle furnace. Palabora Europe Ltd provided one sample for comparison from their South Africa deposit which provides vermiculite used worldwide as a soil amendment. Water release characteristic, cation exchange capacity, pH, mass loss, and bulk density were among the properties assessed. All six vermiculites responded differently on heating, and had a significant variation in their agronomic properties. Water release characteristic varied with the degree of exfoliation and phase composition. Although vermiculites from Tanzania expanded on heating, their capacity to retain plant available water was relatively low as compared to vermiculite from Palabora. Disintegration on heating and the presence of a high amount of iron could be among the factors affecting their water release characteristic. Loss of hydroxyl water was higher in vermiculites than in hydrobiotites. Dehydroxylation enhanced the availability of exchangeable K⁺ and reduced significantly the cation exchange capacity of vermiculites. The optimum exchangeable K⁺ was obtained on heating at a temperature of 600 °C. The pH was unaffected by heating to a temperature of less than 600 °C. At higher temperature, the pH increased in some samples and was accompanied by substantial amounts of exchangeable Mg²⁺. Thus, it was concluded that initial characterization of vermiculites is essential prior to potential agricultural applications in order to optimize their agronomic potential. © 2008 Elsevier B.V. All rights reserved.

Gastrointestinal symbionts of chimpanzees in Cantanhez National Park, Guinea-Bissau with respect to habitat fragmentation

One of the major factors threatening chimpanzees (Pan troglodytes verus) in Guinea-Bissau is habitat fragmentation. Such fragmentation may cause changes in symbiont dynamics resulting in increased susceptibility to infection, changes in host specificity and virulence. We monitored gastrointestinal symbiotic fauna of three chimpanzee subpopulations living within Cantanhez National Park (CNP) in Guinea Bissau in the areas with different levels of anthropogenic fragmentation. Using standard coproscopical methods (merthiolate-iodine formalin concentration and Sheather's flotation) we examined 102 fecal samples and identified at least 13 different symbiotic genera (Troglodytella abrassarti, Troglocorys cava, Blastocystis spp., Entamoeba spp., Iodamoeba butschlii, Giardia intestinalis, Chilomastix mesnili, Bertiella sp., Probstmayria gombensis, unidentified strongylids, Strongyloides stercoralis, Strongyloides fuelleborni, and Trichuris sp.). The symbiotic fauna of the CNP chimpanzees is comparable to that reported for other wild chimpanzee populations, although CNP chimpanzees have a higher prevalence of Trichuris sp. Symbiont richness was higher in chimpanzee subpopulations living in fragmented forests compared to the community inhabiting continuous forest area. We reported significantly higher prevalence of G. intestinalis in chimpanzees from fragmented areas, which could be attributed to increased contact with humans and livestock.

Environment and health with respect to a poverty-related disease: the epidemiology of trachoma in Spain, 1925-1941

Trachoma currently represents one of the three main causes of ‘avoidable' blindness and reaches intolerable dimensions in many developing countries. It was endemic in many regions of eastern Spain until well into the twentieth century. The aim of this paper is to analyze the epidemiological development of this disease in contemporary Spain; to examine its determining factors, particularly environmental and sanitary/health factors, and, finally, to study the health care, environmental and socio-economic measures that led to its control and eradication. We believe that the historical approach not only highlights the role of environmental factors in the development of trachoma, but may also aid in understanding the current epidemiology of trachoma.

Determinants of Firm Growth with respect to Exporting and Innovation Activities: Evidence from Egyptian SMEs

Small and medium-sized enterprises (SMEs) are considered to be the driving engine for employment growth, source of innovation and technological progress. Moreover, the success of small exporters is critical for economic growth and is considered as an important development stage for many SMEs. However, their competitive advantage lies within the firm’s ability to innovate. This thesis contributes to the above literature by examining two main factors believed to promote firm growth namely ‘exporting’ and ‘innovation’ activities. Growing interests on the relationship between exporting, innovation and growth have recently been tackled. However, there remains a gap in literature on the relationship between exporting, innovation and firm growth for SMEs in emerging economies. Previous studies are conducted in developed counties such as UK, Ireland, USA, Germany, and Switzerland, which leaves the gap for those developing countries. Thus, this thesis addresses the gap by examining the importance of innovation and exporting activities in the growth of SMEs in Egypt. It is also the researcher’s intent to recognise the unique contribution of innovation on firm exporting activities covering all sectors. gypt, one of the countries that were tremendously affected by the so-called ‘Arab Spring revolution’, is suffering from slow economic growth, high unemployment and poverty rate. Thus, the government must ensure economic growth and job creation. Programmes to encourage and develop SMEs should be part of inclusive growth strategy. Meanwhile, exporting is regarded as a key factor to help the economy recover from recession and stimulate economic growth. On the other hand, innovation leads to better performance in terms of growth, exporting and productivity. Therefore, SMEs and their exporting and innovation activities should be an integral part of any recovery and growth strategy for the economy. Moreover, Egypt is suffering from the so-called ‘Missing Middle’, which is problematic as medium firms tend to provide better employment growth and productivity. Therefore, more light is to shed on the importance of exporting and innovation in the growth of firms. The research design was quantitative in nature, testing the proposed hypotheses. The study was conducted in 2013 based on questionnaires of 406 Egyptians SMEs. The results of the empirical study suggest that both exporting and innovation activities are important in firm growth. However, the results show that, after controlling for endogeneity, innovation does not affect exporting activities in SMEs.

Can the contra-lateral limb be used as a control with respect to analyses of bone remodelling?

Bone loss may result from remodelling initiated by implant stress protection. Quantifying remodelling requires bone density distributions which can be obtained from computed tomography scans. Pre-operative scans of large animals however are rarely possible. This study aimed to determine if the contra-lateral bone is a suitable control for the purpose of quantifying bone remodelling. CT scans of 8 pairs of ovine tibia were used to determine the likeness of left and right bones. The deviation between the outer surfaces of the bone pairs was used to quantify geometric similarity. The density differences were determined by dividing the bones into discrete volumes along the shaft of the tibia. Density differences were also determined for fractured and contra-lateral bone pairs to determine the magnitude of implant related remodelling. Left and right ovine tibiae were found to have a high degree of similarity with differences of less than 1.0 mm in the outer surface deviation and density difference of less than 5% in over 90% of the shaft region. The density differences (10–40%) as a result of implant related bone remodelling were greater than left-right differences. Therefore, for the purpose of quantifying bone remodelling in sheep, the contra-lateral tibia may be considered an alternative to a pre-operative control.

Practical stability of approximating discrete-time filters with respect to model mismatch using relative entropy concepts

This paper establishes practical stability results for an important range of approximate discrete-time filtering problems involving mismatch between the true system and the approximating filter model. Using local consistency assumption, the practical stability established is in the sense of an asymptotic bound on the amount of bias introduced by the model approximation. Significantly, these practical stability results do not require the approximating model to be of the same model type as the true system. Our analysis applies to a wide range of estimation problems and justifies the common practice of approximating intractable infinite dimensional nonlinear filters by simpler computationally tractable filters.

Practical stability of approximating discrete-time filters with respect to model mismatch

This paper establishes practical stability results for an important range of approximate discrete-time filtering problems involving mismatch between the true system and the approximating filter model. Practical stability is established in the sense of an asymptotic bound on the amount of bias introduced by the model approximation. Our analysis applies to a wide range of estimation problems and justifies the common practice of approximating intractable infinite dimensional nonlinear filters by simpler computationally tractable filters.

Ecological design with respect to the environment of large-scale marina developments in Queensland

Ecological principles have been employed to assist in the sustainability of a suite of 'gateway' marinas currently being developed in Queensland. Tasks included (a) location and fostering of core remnant native vegetation areas, (b) understanding the dynamic patterns of region behaviour using the ecological strategies employed by key flora and fauna species, (c) promoting those native wildlife species best characterising the region, and (d) allocating management actions along elongated buffer zones to the catchment headwaters (rather than only peripheral to the property). The design of infrastructure and its relationship to sustainable landscape development is lacking such a response int eh planning and detailing of new marinas. This paper distinguishes between the practice of landscape ecology and the design of ecological landscapes, offering examples of the principles of the latter in support of the concept of ecological landscape practice.

Weak conformance of process models with respect to data objects

Process models specify behavioral aspects by describing ordering constraints between tasks which must be accomplished to achieve envisioned goals. Tasks usually exchange information by means of data objects, i.e., by writing information to and reading information from data objects. A data object can be characterized by its states and allowed state transitions. In this paper, we propose a notion which checks conformance of a process model with respect to data objects that its tasks access. This new notion can be used to tell whether in every execution of a process model each time a task needs to access a data object in a particular state, it is ensured that the data object is in the expected state or can reach the expected state and, hence, the process model can achieve its goals.