Modeling the Marginal Revenue of Water in Selected Agricultural Commodities: A Panel Date Approach

South Africa is a water-stressed country where water availability is an important constraint to economic and social development, and will become even more so in the future if this scarce resource is not managed effectively. In order to manage this scarce supply of water, we need to value it. This study focuses on the value of water in the agricultural sector, in particular the marginal revenue of water for six irrigation commodities namely avocados, bananas, grapefruit, mangoes, oranges and sugarcane. A quadratic production function was fitted with an SUR model specification in a panel data study from 1975 to 2002 to obtain marginal revenue functions for each of the six commodities. We found that mangoes are the most efficient commodity in its water use relative to revenue generated (marginal revenue of water equals R25.43/m3 in 2002) and sugarcane the least efficient (marginal revenue of water equals R1.67/m3 in 2002). The marginal revenue of water is not an indication of the true “market” price. Neither is it an indication what the administered price should be. The marginal revenue of water is rather a guideline for policy makers to determine which industries or commodities within an industry can generate the largest revenue per unit water applied.Marginal revenue, water efficiency, panel data

The effect of restaurant attributes on customers' expectations and experiences in formal full service restaurants in Port Elizabeth, South Africa

Abstract The purpose of this study was to assess the effect of restaurant attributes on customers' expectations and experiences in formal full service restaurants. The attributes included in this research were food, service and ambience as independent variables and expectations and experiences as dependent variables. The aims were to: (a) assess restaurant attributes that are important for customers' expectations and experiences, (b) to determine which restaurant attributes had a significant relationship with customers' expectations and experiences. The questionnaire was based on Markovic, Raspor & Markovic's (2010) research. In order to meet the surveys' goals, correlation coefficient and regression analysis were conducted. The results of correlation coefficient reveal that all three restaurant attributes had a significant correlation (p<0.05) with expectations. The strongest correlation with expectations was service (r=0.76). Customers' experiences showed that all the attributes had a weak to moderate (r≤0.5) positive correlation with customers' experiences. The strongest correlation with experiences was food (r=0.54). The first regression model showed that all three dining attributes were significantly related (p<0.05) to customers' expectations. The level of service (t=10.73) was rated as the most important attribute for expectations. The second regression model showed that all three dining attributes were significantly related (p<0.05) to experiences. The second model indicated that respondents rated food (t=7.51) as the most important attribute for experience. The results reveal that although good food is an essential component for customers' experiences, however, the level of service plays a pivotal role for customers' expectations in formal full service restaurants

Myomegalin is a novel A-kinase anchoring protein involved in the phosphorylation of cardiac myosin binding protein C

<p>Abstract</p> <p>Background</p> <p>Cardiac contractility is regulated by dynamic phosphorylation of sarcomeric proteins by kinases such as cAMP-activated protein kinase A (PKA). Efficient phosphorylation requires that PKA be anchored close to its targets by A-kinase anchoring proteins (AKAPs). Cardiac Myosin Binding Protein-C (cMyBPC) and cardiac troponin I (cTNI) are hypertrophic cardiomyopathy (HCM)-causing sarcomeric proteins which regulate contractility in response to PKA phosphorylation.</p> <p>Results</p> <p>During a yeast 2-hybrid (Y2H) library screen using a trisphosphorylation mimic of the C1-C2 region of cMyBPC, we identified isoform 4 of myomegalin (MMGL) as an interactor of this N-terminal cMyBPC region. As MMGL has previously been shown to interact with phosphodiesterase 4D, we speculated that it may be a PKA-anchoring protein (AKAP).</p> <p>To investigate this possibility, we assessed the ability of MMGL isoform 4 to interact with PKA regulatory subunits R1A and R2A using Y2H-based direct protein-protein interaction assays. Additionally, to further elucidate the function of MMGL, we used it as bait to screen a cardiac cDNA library. Other PKA targets, viz. CARP, COMMD4, ENO1, ENO3 and cTNI were identified as putative interactors, with cTNI being the most frequent interactor.</p> <p>We further assessed and confirmed these interactions by fluorescent 3D-co-localization in differentiated H9C2 cells as well as by <it>in vivo </it>co-immunoprecipitation. We also showed that quantitatively more interaction occurs between MMGL and cTNI under β-adrenergic stress. Moreover, siRNA-mediated knockdown of MMGL leads to reduction of cMyBPC levels under conditions of adrenergic stress, indicating that MMGL-assisted phosphorylation is requisite for protection of cMyBPC against proteolytic cleavage.</p> <p>Conclusions</p> <p>This study ascribes a novel function to MMGL isoform 4: it meets all criteria for classification as an AKAP, and we show that is involved in the phosphorylation of cMyBPC as well as cTNI, hence MMGL is an important regulator of cardiac contractility. This has further implications for understanding the patho-aetiology of HCM-causing mutations in the genes encoding cMyBPC and cTNI, and raises the question of whether MMGL might itself be considered a candidate HCM-causing or modifying factor.</p

Developing a deliberative-Delphi method for informing national conservation capacity development strategies

Conservation governance requires inter-disciplinary approaches aimed at bridging science, management, and policy divides, which introduces capacity development challenges in developing countries. In particular, there is a need to establish how best to direct capacity development efforts in order to achieve long-term conservation benefits. To help meet this challenge, a deliberative-Delphi method was developed and tested in Namibia based on an integrated Delphi and workshop-based approach. Deliberative-Delphi involves rapid responses to questions followed by consensus workshops to agree emerging themes. The method was applied to researchers in the fields of conservation ecology, conservation governance, and futures thinking (FT) identifying and prioritising ten conservation themes over a two-day period. These themes were then aligned with Namibian conservation policy, and explicated through literature review, providing a roadmap for capacity development interventions (through setting university curricula, research agendas, and future policy changes). The approach can be applied elsewhere to focus conservation capacity development interventions

The birth of airplane stability theory

Airplane stability theory was born at the end of the XIX century and matured around 100 years ago, when airplanes were hardly controllable yet. The success and safety of flights in the pioneer years depended upon largely unknown stability and control characteristics. Understanding the modes of airplane motion has been of paramount importance for the development of aviation. The contributions made by a few scientists in the decades preceding and following the first flight by the Wright brothers set the concepts and equations that, with minor notation aspects, have remained almost unchanged till present day.Magraner Rullan, JP.; Martinez-Val, R. (2014). The birth of airplane stability theory. Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering. 228(9):1498-1506. doi:10.1177/0954410013494139S149815062289PERKINS, C. D. (1970). Development of airplane stability and control technology /1970 Von Karman Lecture/. Journal of Aircraft, 7(4), 290-301. doi:10.2514/3.44167Abzug, M. J., & Larrabee, E. E. (2002). Airplane Stability and Control, Second Edition. doi:10.1017/cbo9780511607141Graham, W. R. (1999). Asymptotic analysis of the classical aircraft stability equations. The Aeronautical Journal, 103(1020), 95-103. doi:10.1017/s0001924000027792Bryan, G. H., & Williams, W. E. (1904). The Longitudinal Stability of Aerial Gliders. Proceedings of the Royal Society of London, 73(488-496), 100-116. doi:10.1098/rspl.1904.0017Wegener, P. P. (1997). What Makes Airplanes Fly? doi:10.1007/978-1-4612-2254-5Pradeep, S., & Kamesh, S. (1999). Does the Phugoid Frequency Depend on Speed? Journal of Guidance, Control, and Dynamics, 22(2), 372-373. doi:10.2514/2.4391Phillips, W. F. (2000). Phugoid Approximation for Conventional Airplanes. Journal of Aircraft, 37(1), 30-36. doi:10.2514/2.2586Pamadi, B. N. (2004). Performance, Stability, Dynamics, and Control of Airplanes, Second Edition. doi:10.2514/4.862274Ananthkrishnan, N., & Ramadevi, P. (2002). Consistent Approximations to Aircraft Longitudinal Modes. Journal of Guidance, Control, and Dynamics, 25(4), 820-824. doi:10.2514/2.4952McRuer, D. T., Graham, D., & Ashkenas, I. (1990). Aircraft Dynamics and Automatic Control. doi:10.1515/978140085598

The mitochondrial DNA T16189C polymorphism and HIV-associated cardiomyopathy: a genotype-phenotype association study

<p>Abstract</p> <p>Background</p> <p>The mitochondrial DNA (mtDNA) T16189C polymorphism, with a homopolymeric C-tract of 10–12 cytosines, is a putative genetic risk factor for idiopathic dilated cardiomyopathy in the African and British populations. We hypothesized that this variant may predispose to dilated cardiomyopathy in people who are infected with the human immunodeficiency virus (HIV).</p> <p>Methods</p> <p>A case-control study of 30 HIV-positive cases with dilated cardiomyopathy and 37 HIV-positive controls without dilated cardiomyopathy was conducted. The study was confined to persons of black African ancestry to minimize confounding of results by population admixture. HIV-positive patients with an echocardiographically confirmed diagnosis of dilated cardiomyopathy and HIV-positive controls with echocardiographically normal hearts were studied. Patients with secondary causes of cardiomyopathy (such as hypertension, diabetes, pregnancy, alcoholism, valvular heart disease, and opportunistic infection) were excluded from the study. DNA samples were sequenced for the mtDNA T16189C polymorphism with a homopolymeric C-tract in the forward and reverse directions on an ABI3100 sequencer.</p> <p>Results</p> <p>The cases and controls were well matched for age (median 35 years versus 34 years, P = 0.93), gender (males 60% vs 53%, P = 0.54), and stage of HIV disease (mean CD4 T cell count 260.7/μL vs. 176/μL, P = 0.21). The mtDNA T16189C variant with a homopolymeric C-tract was detected at a frequency of 26.7% (8/30) in the HIV-associated cardiomyopathy cases and 13.5% (5/37) in the HIV-positive controls. There was no significant difference between cases and controls (Odds Ratio 2.33, 95% Confidence Interval 0.67–8.06, p = 0.11).</p> <p>Conclusion</p> <p>The mtDNA T16189C variant with a homopolymeric C-tract is not associated with dilated cardiomyopathy in black African people infected with HIV.</p

Axial distribution of myosin binding protein-C is unaffected by mutations in human cardiac and skeletal muscle

Myosin binding protein-C (MyBP-C), a major thick filament associated sarcomeric protein, plays an important functional and structural role in regulating sarcomere assembly and crossbridge formation. Missing or aberrant MyBP-C proteins (both cardiac and skeletal) have been shown to cause both cardiac and skeletal myopathies, thereby emphasising its importance for the normal functioning of the sarcomere. Mutations in cardiac MyBP-C are a major cause of hypertrophic cardiomyopathy (HCM), while mutations in skeletal MyBP-C have been implicated in a disease of skeletal muscle—distal arthrogryposis type 1 (DA-1). Here we report the first detailed electron microscopy studies on human cardiac and skeletal tissues carrying MyBP-C gene mutations, using samples obtained from HCM and DA-1 patients. We have used established image averaging methods to identify and study the axial distribution of MyBP-C on the thick filament by averaging profile plots of the A-band of the sarcomere from electron micrographs of human cardiac and skeletal myopathy specimens. Due to the difficulty of obtaining normal human tissue, we compared the distribution to the A-band structure in normal frog skeletal, rat cardiac muscle and in cardiac muscle of MyBP-C-deficient mice. Very similar overall profile averages were obtained from the C-zones in cardiac HCM samples and skeletal DA-1 samples with MyBP-C gene mutations, suggesting that mutations in MyBP-C do not alter its mean axial distribution along the thick filament