A comparison of the responses of mature and young clonal tea to drought.

To assist commercial producers with optimising the use of irrigation water, the responses to drought of mature and young tea crops (22 and 5 years after field planting respectively) were compared using data from two adjacent long-term irrigation experiments in Southern Tanzania. Providing the maximum potential soil water deficit was below about 400-500 mm for mature, and 200-250 mm for young plants (clone 6/8), annual yields of dry tea from rainfed or partially irrigated crops were similar to those from the corresponding well-watered crops. At deficits greater than this, annual yields declined rapidly in young tea (up to 22 kg (ha mm)-1) but relatively slowly in mature tea (up to 6.5 kg (ha mm)- 1). This apparent insensitivity of the mature crop to drought was due principally to compensation that occurred during the rains for yield lost in the dry season. Differences in dry matter distribution and shoot to root ratios contributed to these contrasting responses. Thus, the total above ground dry mass of well-irrigated, mature plants was about twice that for young plants. Similarly, the total mass of structural roots (>1 mm diameter), to 3 m depth, was four times greater in the mature crop than in the young crop and, for fine roots (<1 mm diameter), eight times greater. The corresponding shoot to root ratios (dry mass) were about 1:1 and 2:1 respectively. In addition, each unit area of leaf in the canopy of a mature plant had six times more fine roots (by weight) available to extract and supply water than did a young plant. Despite the logistical benefits resulting from more even crop distribution during the year when crops are fully irrigated, producers currently prefer to save water and energy costs by allowing a substantial soil water deficit to develop prior to the start of the rains, up to 250 mm in mature tea, knowing that yield compensation will occur later

The Role of Local Government Authorities in Facilitating Land Access for Small and Medium Tourism Enterprises Growth in Tanzania

The sustainable development of tourism destinations relies much on Small and Medium Tourism Enterprises found within Local Government Authorities (LGAs). However, tourism destinations have recently being experiencing an increase of population and social economic activities. This situation creates more demand of the land among stakeholders in particular tourism business. Contrary to lager tourism companies Small and Medium Enterprises(SMTEs) has found to be in a less advantageous position in acquiring land from destination which impairing their growth. Thus, land at the destinations is often regarded as one of the constraints for tourism development. The purpose of this study therefore was to examine the role of Local Government authorities in facilitating land management in tourism destinations particularly considering the effects upon the SMTEs growth.  The study was guided by stakeholders’ theory. Using census survey design 232 questionnaires were collected from SMTEs owners/managers at Mto wa Mbu ward in Monduli District. Multiple linear regression was used to determine the relationship between the dependent variable, SMTEs growth and five independent variables. The results strongly confirm the put forward hypothesis “Local government Authorities role in facilitating management of land interests has statistically positive influence on SMTEs growth”, Moreover, five independent variables: land committee, by- law, land allocation, land law and Land policy have statistically significant impact on the growth of small business. Therefore, the theoretical and practical implications of this study refer to stressing the need and important role of LGA’s in managing stakeholders land interests for local tourism that can stimulate the growth of small business within the destination. The study recommends empowerment of Local government Authorities in terms of legal framework to be part in the management regime of local tourism for sustainable development. Keywords: Tourism, SMTEs growth, land policy, Land allocation DOI: 10.7176/JAAS/67-04 Publication date:August 31st 202

Remaining Challenges in Tanzania's Efforts to Eliminate Iodine Deficiency.

To determine iodine levels in salt and iodine deficiency prevalence in school-aged children in 16 districts in Tanzania with previous severe iodine deficiency. A cross-sectional study in schoolchildren. Systematic probability sampling was used to select schools and subjects for goitre assessment and urinary iodine determination. Sixteen districts randomly selected from the 27 categorised as severely iodine-deficient in Tanzania. The study population was primary-school children aged 6-18 years who were examined for goitre prevalence and urinary iodine concentration (UIC). Salt samples from schoolchildren's homes and from shops were tested for iodine content. The study revealed that 83.3% of households (n=21,160) in the surveyed districts used iodised salt. Also, 94% of sampled shops (n=397) sold iodised salt, with a median iodine level of 37.0 ppm (range 4.2-240 ppm). Median UIC in 2089 schoolchildren was 235.0 microg l(-1) and 9.3% had UIC values below 50 microg l(-1). The overall unweighted mean visible and total goitre prevalence was 6.7% and 24.3%, respectively (n=16,222). The age group 6-12 years had the lowest goitre prevalence (3.6% visible and 18.0% total goitre, n=7147). The total goitre prevalence had decreased significantly in all districts from an unweighted mean of 65.4% in the 1980s to 24.3% in 1999 (P<0.05). We believe this difference was also biologically significant. ConclusionThese findings indicate that iodine deficiency is largely eliminated in the 16 districts categorised as severely iodine-deficient in Tanzania, and that the iodine content of salt purchased from shops is highly variable

Mechanism of joint formation and characteristics of interface in ultrasonic welding: Literature review

The study of ultrasonic welding has been going on for more than 50 years. The mechanism of joint formation and characterization of the interface in ultrasonically made joints between metal sheets and wires have been the most thought-provoking area for the researchers. The study of post-welding microstructure, the formation of any intermetallic compound at the interface and their effect on the joint strength, the presence of heat affected zone in the ultrasonically joined sheets has been explored but still, arguably the least understood. Interface characteristics are different in similar and dissimilar combinations of metals. This work presents a comprehensive review of literature regarding the studies on the microstructural analysis at the interface of the joints made by Ultrasonic Welding on different combinations of metal sheets. Additionally, this paper provides an analysis of the observations made by different scientists that promote the future scope of research in this area. The study has been confined to Ultrasonic metal welding only

Determination of paracetamol on electrochemically reduced graphene oxide–antimony nanocomposite modified pencil graphite electrode using adsorptive stripping differential pulse voltammetry

A simple, highly sensitive, accurate, and low-cost electrochemical sensor was developed for the determination of over-the-counter painkiller, paracetamol (PC). The enhanced sensing capabilities of the developed sensor were fabricated by the single-step modification of disposable pencil graphite electrodes (PGEs) with the simultaneous electrochemical reduction in graphene oxide and antimony (II) salts. For this purpose, an electrochemically reduced graphene oxide–antimony nanoparticle (ERGO-SbNP) nanocomposite material was prepared by trapping metallic nanoparticles between individual graphene sheets in the modification of PGEs

Phytochemical study and evaluation of the antiviral activity of aqueous extracts of three medicinal plants; Xylopia aethiopica, Gliricidia sepium and Ocimum gratissimum used in Cote d'Ivoire

Background: The present work is part of the exploration of new antiviral molecules to combat antimicrobial resistance. In purpose, this study determined the phytochemical analysis, cytotoxicity and antiviral activity of extracts from three Ivorian medicinal plants; Gliricidia sepium, Ocimum gratissimum and Xylopia aethiopica against poliovirus 1, a non-enveloped RNA virus. Methodology: Aqueous extract of the three plants, which were identified at the herbarium of National Floristic Center Abidjan, was done using a previously described method. The precipitation or staining technique was used to highlight the chemical groups in the three extracts while the polyphenol content of each extract was assessed by the colorimetric method. Cytotoxicity and antiviral activity tests were performed in 96-well plates. Cytotoxicity of each extract on L20B (a genetically engineered mouse cell line) was determined by observation of the cell line carpet. Antiviral activity of three extracts against poliovirus type I was determined after 72 hours using an assay that measures inhibition of the cytopathic effect on cell culture. Results: The three plant extracts contain polyterpenes, sterols and polyphenols, flavonoids, catechetical tannins, saponosides and quinones but none of the extract contains gallic tannins. With the exception of O. gratissimum, alkaloids were found in extracts from the two other plants, and extract of G. sepium was richer in polyphenol than the other two extracts. The cell carpet of L20B after 72 hours contact period with three extracts remained intact at concentrations ranging from 2 to 1000 μg/ml. The aqueous extract of G. sepium showed higher antiviral activity on poliovirus 1 (74.569%) at 2µg/ml than the extracts of O. gratissimum (45.6112%) and X. aethiopica (44.5247%) after 72 hours of incubation. Conclusion: The extract of G. sepium showed potent antiviral activity against poliovirus 1 than that of O. gratissimum and X. aethiopica. This was justified by its higher polyphenol content than the two extracts

A new ghost cell/level set method for moving boundary problems:application to tumor growth

In this paper, we present a ghost cell/level set method for the evolution of interfaces whose normal velocity depend upon the solutions of linear and nonlinear quasi-steady reaction-diffusion equations with curvature-dependent boundary conditions. Our technique includes a ghost cell method that accurately discretizes normal derivative jump boundary conditions without smearing jumps in the tangential derivative; a new iterative method for solving linear and nonlinear quasi-steady reaction-diffusion equations; an adaptive discretization to compute the curvature and normal vectors; and a new discrete approximation to the Heaviside function. We present numerical examples that demonstrate better than 1.5-order convergence for problems where traditional ghost cell methods either fail to converge or attain at best sub-linear accuracy. We apply our techniques to a model of tumor growth in complex, heterogeneous tissues that consists of a nonlinear nutrient equation and a pressure equation with geometry-dependent jump boundary conditions. We simulate the growth of glioblastoma (an aggressive brain tumor) into a large, 1 cm square of brain tissue that includes heterogeneous nutrient delivery and varied biomechanical characteristics (white matter, gray matter, cerebrospinal fluid, and bone), and we observe growth morphologies that are highly dependent upon the variations of the tissue characteristics—an effect observed in real tumor growth