Search

Beaches are areas of high economic value derived largely from high demand for recreational goods and services. These outdoor recreational resources are likely to succumb to considerable health pres...

This paper reports the first formal non-market valuation of a major mountain biking event in South Africa by applying the individual travel cost method (TCM). Due to the non-negative, integer nature of the trip data, several count data models were estimated. Mountain biking is fast becoming one of South Africa's most popular recreational sports and these estimates of economic value may assist policy-makers in managing mountain biking venues in general, and congestion conflicts, specifically. The locus of this study is the annual Trans Baviaans mountain biking event staged in the Baviaanskloof Mega-Reserve situated in the Eastern Cape Province of South Africa – part of this reserve was declared a World Heritage Site in 2004. In total, 288 fully completed questionnaires were collected and used in the analysis. The economic value estimated, by employing a negative binomial model with endogenous stratification, for trips taken to the event during 2014 amounted to ZAR2308 (US$201) per person per trip. Management Implications The paper underlines the substantial benefits of a MTB event. The provided findings are valuable ● to plan MTB events at other locations, ● to compare the benefits with other landscape related sport events, and ● to improve MTB events including environmental information and mitigation of impacts.

Recent biological studies with ultra-high dose-rate (> 40 Gy/s) irradiation demonstrate the killing of tumors along with a reduction in the side-effect on normal tissues. These features can suggest the alternative radiotherapy method. The radio-biological mechanisms need to be understood, and to be applied tumor treatment. Biological validations of the ultra-high dose-rate beam are required. The 6-MeV electron linear accelerator constructed in 2015 at the Dongnam Institute of Radiological & Medical Sciences was upgraded to generate an electron beam at an ultra-high dose rate and to provide preclinical irradiation for in vitro studies of cells and small animals. The irradiation device was designed with a dual scattering foil system to achieve a uniform beam distribution with a diameter of 30 mm at a distance of 110 mm from the primary foil. The 6-MeV accelerator operating with a 6-MW pulse modulator based on a thyratron-switched pulse-forming network provides beam operation per pulse utilizing a single-board computer to control the pulse timing. The film dosimetry at a depth of 10 mm in a water phantom of the irradiation device demonstrated that a beam with an RF power of 2.5 MW and an electron-gun heating current of 2 A produced a dose per pulse of 4.22±0.12 Gy/pulse. This resulted in a dose rate of 422 Gy/s with a pulse rate of 100 Hz. The upgraded accelerator was successfully tested for preclinical use and is currently in full operation with studies being performed on the radio-biological effects of ultra-high dose-rate beam. The paper describes the design features of the ultra-high dose-rate electron beam generated from the 6-MeV accelerator and the dose measurement using the irradiation device. The design of the preclinical irradiator is also discussed.

Introduction Down syndrome (DS) is the most common aneuploidy, caused by an extra copy of all or part of chromosome 21 (chr21). Differential microRNA (miRNA) expression is involved in many human diseases including DS. However, the genome-wide changes in miRNA expression in DS fetal placentas have yet to be determined, and the function of these changes is also unclear. Methods We profiled genome-wide miRNA expression in placenta samples from euploid or DS fetuses by using microarray technology and predicted the functions of differentially expressed miRNAs using bioinformatics tools. Results Thirty-four miRNAs were significantly differentially expressed in the DS placenta compared with the normal placenta (16 up-regulated and 18 down-regulated). However, expression of chr21-derived miRNAs did not change. Predicted target genes included 7434 genes targeted by up-regulated miRNAs and 6071 genes targeted by down-regulated miRNAs. Seventy-six of these target genes were located on chr21 (10 genes controlled by down-regulated miRNAs and 34 genes by up-regulated miRNAs, and 32 genes by both). Target genes on chr21 were significantly associated with DS and DS-related disorders, such as mental retardation, neurobehavioral manifestations, and congenital abnormalities. Discussion To our knowledge, this is the first genome-wide study to comprehensively survey placental miRNAs in DS fetuses. Our results provide new insight into miRNA expression in placentas of fetuses with DS. Additionally, our findings indicate that the differentially expressed miRNAs in the DS placenta may potentially affect various pathways related to DS pathogenesis.

Introduction To investigate the association between pregnancies with small for gestational age (SGA) neonates and the concentration of cell-free fetal DNA or cell-free total DNA in maternal plasma during the first and second trimesters using tissue-specific epigenetic characteristics of the SERPINB5 gene. Methods A nested case–control study was conducted with maternal plasma collected at 11 to 26 gestational weeks from 51 women with SGA neonates and 102 controls. We performed a real-time quantitative methylation-specific PCR to quantify concentrations of unmethylated- SERPINB5 (U- SERPINB5 ) as a cell-free fetal DNA marker and methylated- SERPINB5 (M- SERPINB5 ) as a cell-free total DNA marker. Results A positive correlation was observed between U- SERPINB5 and M- SERPINB5 concentrations in both control ( r = 0.363, p r = 0.548, p SERPINB5 or M- SERPINB5 was significantly positive correlated with gestational age at sampling in both controls (U- SERPINB5 : r = 0.397, p SERPINB5 : r = 0.275, p = 0.005) and SGA (U- SERPINB5 : r = 0.274, p = 0.052; M- SERPINB5 : r = 0.439, p = 0.001). However, the concentration of U- SERPINB5 or M- SERPINB5 was not correlated with birthweight. At 11–14 weeks, U- SERPINB5 and M- SERPINB5 concentrations in SGA did not differ significantly from those of controls. There were also no statistically significant differences in the concentrations of U- SERPINB5 and M- SERPINB5 between SGA and controls at 15–26 weeks of gestation. Discussion Our findings suggest that U- SERPINB5 and M- SERPINB5 concentrations in maternal plasma during early pregnancy are not associated with pregnancies who delivered SGA neonates.

The objectives of this research are to investigate effects of sludge properties in terms of particle size composition on performance of physical and chemical cleaning and to understand fouling mechanisms of the specific feed solutions. The sludge was centrifuged at three rotational speeds to differentiate particle size distributions, and the supernatant and residual flocs were used for microfiltration and cleaning processes. The filtration flux with the flocs was greater than those of the three supernatants, which indicates that fouling was greater with supernatants. Taking into account that the solid concentrations of the raw sludge and the residual flocs were 10 times greater than those of the supernatants, the reduction in flux for the supernatants is significant. The flux was recovered to 64% of the clean water flux at the maximum efficiency by two cleaning of membrane fouled with supernatant treated at 1,000 rpm. In addition, increasing removal of coarse particles by applying higher centrifug...

Parametric regression models of hedonic price functions suffer from two main specification issues: the identification of appropriate dependent and independent variables, and the choice of functional form. Although the first issue remains relevant with the use of nonparametric regression models, the second issue becomes irrelevant since these models do not presume functional forms a priori. We estimate a linear parametric model via OLS, which fails a common specification test, before showing that recently developed nonparametric regression methods outperform it significantly. In addition to estimating the models, we compare the out-of-sample prediction performance of the OLS and nonparametric models. Our data reveals that the nonparametric models provide more accurate predictions than the parametric model.

Using beach visitation data collected via the administration of a questionnaire to 226 respondents, this paper estimates a random utility model of beach recreation. The relative value of selected attributes of beaches is estimated, and the recreational values of lost access to four Blue Flag beaches in the Nelson Mandela Bay area, namely Kings beach, Humewood beach, Hobie beach and Wells Estate beach, respectively are calculated to be R44.73, R24.61, R37.85 and R2.68 per person, per trip.

The Rhodes trout fishery, located in the North Eastern Cape, is one of South Africa’s premier fly-fishing destinations. The integrity of the fishery is, however, under threat due to various land-use practices, which could weaken its appeal as a tourist attraction. The aim of this study is to estimate the amount recreational users are willing to pay for a project to improve the trout habitat of waters managed by the Wild Trout Association (WTA) in this fishery in order to improve its fish population density by 100 per cent. Data were collected from a biased sample of 96 respondents via a questionnaire during September 2006 to September 2007. The median estimated willingness-to-pay (WTP) for the project was R245 per annum per person, and the total WTP was estimated at R171 500 per annum. A valuation function to predict WTP responses was also estimated, and showed that gross annual pre-tax income and the number of visits per annum were positive determinants of WTP. The results of this study show that policy-makers should take heed of the importance trout fly fishers attach to this fishery when declaring trout zones in the upper catchments of South Africa. The aggregate WTP estimation, however, constitutes only a partial analysis of value. A number of other factors and environmental value streams need to be analysed and compared with the value estimates generated by this study if adequate holistic decision-making is to take place with regard to trout stream improvement. More specifically, the aggregate WTP estimated in this study must be viewed as only one input into a comprehensive social cost-benefit analysis to determine the desirability of trout stream improvement for wider society.

Acoustic emission transducers were used to study the brush/rotor interface of a homopolar motor as a function of design parameters such as speed and load. The results indicate that acoustic emission is well suited for in situ monitoring of brush wear and rotor conditions, and for analyzing the tribological phenomena occurring at the brush/rotor interface.

Fatty acid ω-3 desaturase (FAD) is the key enzyme catalyzing the formation of trienoic fatty acids. We utilized an Arabidopsis FAD7 gene and the seven independent transgenic rice plants harbouring 1 to 3 copies of this gene were generated. The expression of FAD7 mRNA was different among independent transgenic lines regardless of the copy number. The total linolenic acid (18:3) contents reduced by about 7 – 32 % in transgenic rice plants but the linoleic acid (18:2) content increased accordingly. With or without wounding treatments, the jasmonate content was higher in transgenic lines than in wild-type rice plant. The transgenic lines overproducing jasmonate also showed increased expression of PR1b mRNA and allene oxide synthase inresponse to wounding.

Transgenic rice plants harbouring Bacillus subtilis protoporphyrinogen oxidase (Protox) gene, which is targeted into plastid, were generated by Agrobacterium-mediated transformation using a rice (Oryza sativa L. cv. Dongjin) and their gene integration at T1 generation by Southern and mRNA expression in T2 generation by Northern blotting were analyzed. Their herbicide-resistant trait was further confirmed by in vitro leaf segment assay and in planta bioassays such as seed germination assay and measurement of growth inhibition. The herbicide oxyfluorfen resistance in transgenic rice plants was not very high. The results showed that the Protox from B. subtilis can not be applicable as a gene source to generate a high level oxyfluorfen tolerance in plants.

Targeted oncolytic viruses and immunostimulatory therapeutics are being developed as novel cancer treatment platforms. These approaches can be combined through the expression of immunostimulatory cytokines from targeted viruses, including adenoviruses and herpesviruses. Although intratumoral injection of such viruses has been associated with tumor growth inhibition, eradication of distant metastases was not reported. The major limitations for this approach to date have been (1) inefficient intravenous virus delivery to tumors and (2) the lack of predictive, immunocompetent preclinical models. To overcome these hurdles, we developed JX-594, a targeted, thymidine kinase − vaccinia virus expressing human GM-CSF (hGM-CSF), for intravenous (i.v.) delivery. We evaluated two immunocompetent liver tumor models: a rabbit model with reproducible, time-dependent metastases to the lungs and a carcinogen-induced rat liver cancer model. Intravenous JX-594 was well tolerated and had highly significant efficacy, including complete responses, against intrahepatic primary tumors in both models. In addition, whereas lung metastases developed in all control rabbits, none of the i.v. JX-594-treated rabbits developed detectable metastases. Tumor-specific virus replication and gene expression, systemically detectable levels of hGM-CSF, and tumor-infiltrating CTLs were also demonstrated. JX-594 holds promise as an i.v.-delivered, targeted virotherapeutic. These two tumor models hold promise for the optimization of this approach.

The Sundays River Estuary, situated in the Eastern Cape, South Africa, has excessive recreational demand for estuarine services, specifically recreational fishing. The estuary has been over-fished, putting its sustainability at risk. Various management interventions may be required in order to save it, but how is this to be done without reducing welfare? The main aim of this paper is twofold: first, to assess and comprehend the economic value of the estuarine resources at stake; and, second, to propose policy measures to redress the situation (excessive demand, specifically recreational fishing). An application of a choice experiment reveals that the physical size of fish stocks is a very important predictor of recreational choice at the Sundays River Estuary, and it is recommended that demand be curtailed through an increase in the boat license fee for using the estuary of ZAR174 per annum. Keywords : Estuary, demand management, recreational attributes, recreational fishery, choice experiment