Water resources of Africa, the cases of Cameroun and Ghana

Includes bibliographical references.This study is a progress report on 'Water resources of Africa, the cases of Cameroun and Ghana'.Sponsored by the National Science Foundation GA 29149

Decoloniality, Language, Identity and Communication: The Case Study of Cameroonian Pidgin

In this paper the intersection between decoloniality language identity and communication is discussed in how they come together in the use or refusal to use Cameroon Pidgin CamP The paper draws on the concepts of coloniality and decoloniality and relates them to language as used by Cameroonians in South Africa The argument is that it is surprising that many Cameroonian Pidgin speaking immigrants are choosing not to communicate in Pidgin especially since usage of the language from the home country could become a locus of solidarity and reproduction of one aspect of the everydayness of home in a new country This article relies on a qualitative framework comprised of openended interviews focus group discussions and participant observation to explore the role of language identity and decoloniality in communication The idea is to explore how these issues and themes intersect and what the intersections themselves tell us firstly about the nature of identity and secondly about the relationship between language and identit

Selective Conversion Of Glycerol To Lactic Acid By CaO γ-Al2O3 Supported Catalyst

Pengeluaran biodiesel telah membangun dengan pesat di Malaysia dan ia menjana lebihan gliserol mentah sebagai produk utama bersama. Berdasarkan keadaan semasa, penukaran gliserol kepada bahan kimia nilai tambah yang lebih tinggi seperti asid laktik telah menarik ramai penyelidik untuk memastikan kemampanan ekonomi industri biodiesel. Dalam kajian ini, CaO disokong pada alumina, γ-Al2O3 telah disintesis dengan berbeza muatan CaO (20-50 % berat) dan pengkalsinan terakhir pada suhu optimum iaitu 700 ° C. Pemangkin yang disintesis telah dicirikan melalui analisis permukaan, SEM, TEM, XRD, EDX, FTIR, TGA dan N2 penjerapan sesuhu. Ciri-ciri pemangkin dihubungkaitkan dengan aktiviti mangkin dalam eterifikasi gliserol kepada asid laktik dan prestasi yang ditunjuk berdasarkan penukaran gliserol dan hasil asid laktik. Hasil yang tinggi asid laktik telah dikenal pasti dengan menggunakan pemangkin 30CaO/γ-Al2O3 yang telah disediakan dengan menggunakan 30% berat muatan CaO memuatkan dan dikalsinasikan pada suhu 700 ° C dalam pengeluaran asid laktik daripada gliserol. Kesan keadaan tindak balas seperti muatan pemangkin (5-20 % berat), suhu tindak balas (270-330 °C), masa tindak balas (0.5 - 4 jam) juga dijelaskan dan dihubungkaitkan dengan ciri-ciri mangkin. Selain itu, keadaan tindak balas terbaik diperolehi pada muatan pemangkin 10% berat, suhu tindak balas 290 ° C dan masa tindak balas 2 jam di bawah keadaan, 95% daripada penukaran gliserol dan 49% hasil asid laktik telah dicapai. Dari segi penggunaan semula, pemangkin ini adalah boleh digunakan semula sehingga 3 kali dalam tindak balas dengan penurunan dari 95% kepada 73% dalam penukaran gliserol, manakala penurunan dalam hasil asid laktik dari 47% kepada 27% dalam aktiviti pemangkin. Kajian kinetik pembentukan asid laktik berjaya dilaksanakan dan didapati menepati model kinetic tertib pertama terhadap glycerol dengan tenaga pengaktifan sebanyak 61.730 kJ/mol. Sebagai kesimpulan, 30CaO/γ-Al2O3 merupakan pemangkin yang menunjukkan aktiviti yang baik dan ia merupakan pemangkin aktif yang sesuai untuk digunakan dalam tindak balas yang melibatkan gliserol. _______________________________________________________________________________________________________ The biodiesel production has been developing rapidly in Malaysia and it generates a surplus of crude glycerol as the primary co-product. Based on the current situation, the conversion of glycerol to higher value-added chemicals like lactic acid has attracted many researchers to ensure the economic sustainability of the biodiesel industry. In the present work, CaO supported on alumina, γ-Al2O3 catalyst was synthesized with different CaO loadings (20-50 wt. %) and the final calcination at optimum temperature was 700 °C. The synthesized catalyst were then characterized by means of surface analysis, SEM, TEM, XRD, EDX, FTIR, TGA and N2 adsorption-desorption isotherm. The characteristics of the catalysts were correlated with the catalytic activity in glycerol etherification and the performance demonstrated based on the glycerol conversion and lactic acid yield. It was found that high yield of lactic acid was identified by using 30CaO/γ-Al2O3 catalyst which was prepared using 30 wt.% of CaO loading and calcined at 700 °C in the production of lactic acid from glycerol. Effects of reaction condition such as catalyst loadings (5-20 wt. %), reaction temperature (270-330 °C), reaction time (0.5-4 h) were also explained and correlated with the characteristics of the catalysts. On top of that, the best reaction conditions were obtained at 10 wt. % of catalyst loading, a reaction temperature of 290 °C and a reaction time of 2 h. Under these conditions, using 30CaO/γ-Al2O3 catalyst, 95 % of glycerol conversion and 49 % of lactic acid yield were obtained. In terms of reusability, this catalyst was reusable for up to 3 times in this reaction with decrease from 95% to 73% for glycerol conversion, while decrease from 47% to 27% in lactic acid yield in the catalytic activity. The kinetic study of lactic acid formation was successfully conducted with a first order kinetic model and the activation energy of reaction of 61.730 kJ/mol was determined. As a conclusion, 30CaO/γ-Al2O3 catalyst showed good activity and it is an active catalyst that is suitable to be used in the reaction involving glycerol

Hydrogen peroxide enhances the expression and function of Giα proteins in aortic vascular smooth muscle cells from Sprague-Dawley rats : role of growth factor receptors transactivation

Nous avons récemment démontré que les espèces réactives oxygénées induisent une augmentation de l’expression des protéines Giα dans les cellules du muscle lisse vasculaire (CMLV) provenant d’aortes de rats spontanément hypertendus (SHR, de l’anglais spontaneously hypertensive rats). La présente étude a pour but d’étudier les effets du peroxyde d’hydrogène (H2O2), un oxydant qui induit le stress oxydatif, sur l’expression de Giα et sur l’activité de l’adénylate cyclase, et d’explorer les voies de signalisation sous-jacentes responsables de cette réponse. Nos résultats montrent que H2O2 induit une augmentation de l’expression des protéines Giα-2 et Giα-3 de manière dose- et temps-dépendante avec une augmentation maximale de 40-50% à 100 µM après 1 heure, sans affecter l’expression de Gsα. L’expression des protéines Giα a été maintenue au niveau normal en presence de AG 1478, AG1295, PD98059 et la wortmannine, des inhibiteurs d’EGF-R (de l’anglais epidermal growth factor receptor), PDGFR-β (de l’anglais platelet-derived growth factor receptor β), de la voie de signalisation ras-ERK1/2 (de l’anglais extracellular regulated kinase1/2), et de la voie de la PI3Kinase-AKT (de l’anglais phosphatidyl inositol-3 kinase), respectivement. En outre, le traitement des CMLV avec H2O2 a induit une augmentation du degré de phosphorylation d’EGF-R, PDGF-R, ERK1/2 et AKT; et cette expression a été maintenue au niveau témoin par leurs inhibiteurs respectifs. Les inhibiteurs d’EGF-R et PDGF-R ont aussi induit une diminution du degré de phosphorylation de ERK1/2, et AKT/PKB. En outre, la transfection des cellules avec le siRNA (de l’anglais, small interfering ribonucleic acid) de EGF-R et PDGFR-β a atténué la surexpression des protéines Giα-2 et Giα-3 induite par le traitement au H2O2. La surexpression des protéines Giα induite par H2O2 a été corrélée avec une augmentation de la fonction de la protéine Giα. L’inhibition de l’activité de l’adénylate cyclase par de faibles concentrations de GTPγS après stimulation par la forskoline a augmenté de 20% dans les cellules traitées au H2O2. En outre, le traitement des CMLV au H2O2 a aussi accru l’inhibition de l’activité de l’adénylate cyclase par les hormones inhibitrices telles que l’angiotensine II, oxotrémorine et C-ANP4-23. D’autre part, la stimulation de l’adénylate cyclase induite par GTPγS, glucagon, isoprotérénol, forskoline, et le fluorure de sodium (NaF) a été atténuée de façon significative dans les cellules traitées au H2O2. Ces résultats suggèrent que H2O2 induit la surexpression des protéines Giα-2 and Giα-3 via la transactivation des récepteurs des facteurs de croissance EGF-R, PDGFR-β et l’activation des voies de signalisation ras-ERK1/2 et PI3K-AKT Mot-cles: Protéines Giα, peroxyde d’hydrogène, stress oxydant, récepteurs des facteurs de croissance, MAP kinases, adénylate cyclase, hypertensionWe recently have shown that reactive oxygen species contribute to the enhanced expression of Giα proteins in vascular smooth muscle cells (VSMC) from spontaneously hypertensive rats (SHR). The present study was undertaken to examine if H2O2, an oxidant that induces oxidative stress could also enhance the expression of Giα proteins and associated adenylyl cyclase signalling in aortic VSMC and to further explore the underlying signaling pathways responsible for this response. Treatment of cells with H2O2 increased the expression of Giα-2 and Giα-3 proteins but not that of Gsα proteins in a concentration- and time-dependent manner. A maximal increase of 40-50% was observed at 100µM and 1h. The enhanced expression of Giα proteins was restored to control levels by AG 1478, AG1295, PD98059 and wortmannin, inhibitors of epidermal growth factor receptor (EGF-R), platelet-derived growth factor receptor (PDGFR-β), the mitogen-activated protein kinase (MEK1/2), and PI3 kinase respectively. In addition, treatment of VSMC with H2O2 also increased the phosphorylation of EGF-R, PDGF-R, ERK1/2 and AKT and this increased phosphorylation was attenuated to control levels by the respective inhibitors, whereas the inhibitors of EGF-R and PDGE-R also attenuated the enhanced phosphorylation of ERK1/2 and AKT to control levels. Transfection of cells with EGF-R and PDGFR-β siRNA followed by H2O2 treatment restored the H2O2-induced enhanced expression of Giα-2 and Giα-3 proteins to control levels. The increased expression of Giα proteins by H2O2 was reflected in the increased Gi functions. The inhibition of forskolin (FSK)-stimulated AC activity by low concentration of GTPγS (receptor- independent Gi functions) was increased by about 20% by H2O2 treatment. Moreover, treatment of cells with H2O2 also resulted in an increased Ang II-, C-ANP4-23, and oxotremorine-mediated inhibition of AC (receptor-dependent functions of Gi). On the other hand, Gsα-mediated stimulation of AC by GTPγS, glucagon, isoproterenol, FSK, and NaF was significantly decreased in H2O2-treated cells. These results suggest that H2O2 increases the expression of Giα-2 and Giα-3 proteins in VSMC through the transactivation of EGF-R, PDGFR-β and associated ERK1/2 and PI3K signalling pathways. Keywords: Giα proteins, hydrogen peroxide, adenylyl cyclase, oxidative stress, MAP kinase, growth factor receptors, hypertension

Effet de la maladie des taches angulaires sur le rendement des varietes de haricot commun (Phaseolus vulgaris l.) a Foumbot dans L’ouest Cameroun

Cette étude a été menée à l’IRAD de Foumbot dans le but d’examiner l’effet de la maladie des taches angulaires (MTA) sur le rendement des variétés améliorées de haricot commun. Six variétés améliorées de haricot ont été semées dans un dispositif complètement randomisé avec trois répétions. Les données collectées sur l’incidence et la sévérité de la maladie, ainsi que le rendement de chaque variété ont été soumises à une Analyse des Variances. Les résultats montrent que l’incidence et la sévérité de la maladie ainsi que le rendement ont été significativement différents (P d ≤ 0,05) entre les variétés. L’incidence de la maladie a été significativement plus élevée chez les variétés naines dans la proportion de 100 %, que chez les variétés grimpantes dans la proportion 85 % au 50e jour après semis. La maladie a été plus sévère chez les variétés naines (39 %) que chez les variétés grimpantes (20 %). Les variétés grimpantes ont été les plus productrices. L’étude montre que la MTA du haricot commun réduit significativement le rendement en grains de cette culture à Foumbot et la variété grimpante NUV-6 se présente comme un bon candidat en vue de la sélection pour la résistance contre cette maladie.Mots clés : Maladie des taches angulaires, haricot, variété, rendement.English AbstractEffect of angular leaf spot disease on the yield of common bean (Phaseolus vulgaris l.) varieties at Foumbot in Western CameroonThis study was conducted at IRAD of Foumbot to examine the effect of Angular Leaf Spot (ALS) disease on the performance of improved varieties of common bean. Indeed, six improved bean varieties were sown in a completely randomized design with three replications. The data collected on the incidence and severity of the disease, as well as the yield of each variety were subjected to Analysis of Variances. The results show that the incidence and severity of the disease, as well as the yield were ignificantly different (P d ≤ 0.05) between the varieties with respect to days after sowing (DAS). From 50 days after sowing (DAS), disease incidence was higher for bush varieties in proportion of 100 % than climbing varieties in proportion of 85 %. The disease was more severe on the bush varieties than the climbing varieties respectively in proportions of 39 % and 20 %. Climbing varieties were the most productive compared to bush varieties. The study shows that the ALS disease of common bean significantly reduce the yield of both the climbing and bush varieties in Foumbot. But in terms of disease, climbing variety NUV-6 proved best as it showed some resistance to ALS and had quality seeds.Key words : Angular leaf spot disease, bean, variety, yiel

Negotiation of identities and language practices among Cameroonian immigrants in Cape Town

Philosophiae Doctor - PhDThis thesis is an exploration of the historical, socio-cultural, economic, and political settings in which identities are negotiated and performed among Cameroonian immigrants in Cape Town. Focusing on language as localized practices and different interaction regimes, the thesis investigates how Cameroonian immigrants maintain and reconfigure the Anglophone/Francophone identity options in novel and hybrid ways. In addition, the study examines how ideologies favouring different languages are reproduced and challenged in translocal and transnational discourses. Guided by the poststructuralist theories the thesis explores the stance that reality is socially constructed, based on symbolic and material structural limitations that are challenged and maintained in interaction. That is, whatever we do or believe in, is supported by some historical or cultural frames of meanings in our lived world, which often gives room to some manoeuvre to do things in a new way. The study adopts a multiplex interpretive approach to data collection. This entails a qualitative sociolinguistic approach where interviews, discussion and observations at different socio-economic places namely; meetings, workplaces, homes, restaurants, drinking spots and many sites from all over Cape Town, were explored. The study suggests that Cameroonians have a multiplicity of identity options, which are manifested and negotiated performatively through language, dress code, song, food, business, and other practices that comprise their lifestyles. These identities are translocal and transnational in nature, and tend to blend South African, Cameroonian, and even American traits. It is also suggests that the different identity options which they manifest are highly mobile, enabling Cameroonians to fit into South African social structures as well as the Cameroonian ways of doing things. Additionally, the multiplicity of identities that Cameroonians manifest, blur the fault-line between Anglophone/Francophone identities. It is evident from the study that hybridity and the reconstruction practices are not only confined to languages. Hybridity also extends to discourse orders especially in terms of how meetings are conducted. The Cameroonian meetings captured through the activities of Mifi Association and CANOWACAT are characterised by ‘disorder of discourse’ in which both formal and informal versions of English and French are used separately or as amalgams alongside CPE and their national languages, not only in side talks, but also when contributing to the meeting proceedings. Ultimately, the study concludes that Cameroonians are social actors making up an indispensable part of the social interaction in the Cape Town Diaspora. Just as they influence the languages, the entrepreneurial practices, and spaces in which they interact, the Cameroonian immigrants are also transformed. The major contribution of the study is that it adds to the recent debates about the nature of multilingualism and identities in late modern society. It emphasises that languages and identities are fluid, complex, and unstable. The distinction or boundaries between the various languages in multilingual practices are also not as clear-cut. This leads to a reframing of voice and actor hood as meaning is constructed across translocal and transnational contexts and domains in a networked world transformed by the mobility of endless flows of information, goods, ideas, and people. Thus, the study contributes to those arguing for a paradigm shift in sociolinguistic theory in which language is not a property of groups, nor is it an autonomous and bounded system fixed in time and space. Thus, identities, languages and the spaces of interaction are not fixed systems; identities, languages, and spaces are dynamic and in a state of flux. This in turn questions the notions of multilingualism and language itself, as well as the veracity of concepts such as code-switching, speech community, language variation, as the search for a sociolinguistic framework that can deal with phenomena predicated by motion, instability, and uncertainty, continues.South Afric

Screen house and field resistance of taro cultivars to taro leaf blight disease (Phytophtora colocasiae)

Article PurchasedIntroduction: Taro leaf blight disease cause by Phytophtora colocasiae has become an economic disease in Cocoyam growing regions of Cameroon. Aims: To screen for resistance 10 improved and 4 local cultivars of taro against taro leaf blight disease. Study Design: A randomized complete block design study. Place of Study: Studies were conducted at the International Institute of Tropical Agriculture (IITA) Yaounde Nkolbisson from July 2013 to January 2014. Methodology: Taro cultivars from tissue culture were planted in the screen house conditions and tested for virulence and pathogenicity with 4 isolates of Phythophthora colocasiae at spore density of 3×104 spores /ml of distilled water. Plants were planted in the field to assess disease incidence and severity. Results: The results obtained on the different taro cultivars, revealed that all the 4 isolates showed variable pathogenicity. They caused lesions on inoculated leaves. There was variability in pathogenicity based on the small lesion lengths produced on cultivars, these included BL/SM132 and Red petiole. Isolate 3 showed a stronger sensitivity to leaf collapse and defoliation irrespective of the cultivar tested. There was a significant difference (p = 0.05) in tissue collapse and leaf defoliation on exposure to the different fungal isolates. The result of field infection rates of P. colocasiae at 126 DAP-154 DAP on 10 improved and 4 local cultivars indicated that there was significant variability (p = 0.05) in incidence and disease severity, with high incidence and severity occurring at 154 DAP in all cultivars. Improved cultivar BL/SM132 showed no classic symptoms of P. colocasiae and therefore it was resistant to Phytophthora colocasiae. Conclusion: The results obtained on virulence and pathogenicity of Phythophthora colocasiae on the different taro cultivars revealed that all the 4 isolates showed variable pathogenicity. They caused lesions, on inoculated leaves. Isolate 3 showed a stronger sensitivity to leaf collapse and defoliation irrespective of the cultivar tested. The result of field infection rates of P. colocasiae at 126 DAP-154 DAP on 10 improved and 4 local cultivars indicated that there was a significant variability (p = 0.05) in disease incidence and severity, with high incidence and severity occurring at 154 DAP in all cultivars. Improved cultivar BL/SM132 showed no classic symptoms of P. colocasiae and therefore it was resistant to Phytophthora colocasiae as compared to all the other cultivars which showed high severity rates of infection of the disease and thus were susceptible to the disease

Cultural, morphological and pathogenic variability of Phytophthora colocasiae isolate from taro in Cameroon

There exist 124 species of Phytophthora worldwide that cause serious diseases in natural ecosystems. These species have been identified using molecular methods. This study was conducted to determine the cultural, morphological and pathogenic variability of isolates of P. colocasiae processed from cultivars of Taro from Cameroon.The study was conducted in three agroecological regions, namely, Yaoundé, Bambui and Ekona where the disease was prevalent. Morphology showed that the mycelia were circular on all the isolates, in the three study zones. Mycelia colours ranged from white to cotton white. The colours of the culture media, after inoculation and mycelia growth, were the same. There was a significant difference (P<0.05) in mycelial growth among the isolate; with the longest of 5.5 cm in V6 juice agar media. Spore morphology was either spherical or ovoid in all the Taro isolates, in all culture media, except water medium. All four isolates were pathogenic to the four cultivars of Taro, causing lesions on leaves on inoculation. The most virulent fungi isolates were L1 (dark green petiole with small leaves) and L2 (red petiole with small leaves), which caused the largest lesion (>10 mm) in Taro cultivars during 14 days of inoculation. &nbsp

Application of in-vitro micropropagation technique for sustainable production of four local taro cultivars [Colocasia esculenta (L.) Schott] in Cameroon

Open Access JournalTaro leaf blight disease has recently been reported in Cameroon to cause between 50 and 100% yields loss of taro in most of the agro-ecological crop growing regions. This has led to a significant reduction in disease-free planting materials, edible crop and increased. The Meristem culture technique has been used to produce crop plants free of viruses and fungi especially in vegetative propagated colocassia plants. This aimed at applying in-vitro micro-propagation technique for sustainable production of four local taro cultivars in Cameroon. This study was conducted at the Root and Tuber Tissue Culture Laboratory, of the Institute of Agricultural Research for Development (IRAD), Bambui from April 2015 to November 2016. Micro-plants from four local taro cultivars were produced in vitro from apical meristem tips. The tip meristems were excised from corms of the four local taro cultivars. The excised explants were surface sterilized with alcohol and sodium hypochlorite in sequence steps at different concentrations. Meristems were cultured at establishment stage on Murashige and Skoog (MS) medium with 30 g of sugar, 1.1 ml of 6-benzylaminopurine and 7 g of agar. Shoots proliferation was induced in MS with 2.2 ml of 6-benzylaminopurine (BAP). Result shows a significant difference at p≤0.5 in number of shoots, petiole length, open leaf and corm diameter among the cultivars and no significant variation in mean number of senescence leaf with respect to all the cultivars, at 60 days of shoot tip culture. At rooting stage, taro shoots were cultured on MS media supplemented with 10 ml of 0.1 mg/ml naphthalene acetic-acid (NAA). Roots were produced on all the cultivars with excellent mean growth rate of 14.7 ± 0.69 recorded in cultivar with dark green petiole and small leaves