Pheochromocytoma (PHEO) is a rare endocrine tumor from the chromaffin cells in the adrenomedullary gland and sympathetic/parasympathetic ganglia, secreting one or more catecholamines. It is frequently associated with ...Pheochromocytoma (PHEO) is a rare endocrine tumor from the chromaffin cells in the adrenomedullary gland and sympathetic/parasympathetic ganglia, secreting one or more catecholamines. It is frequently associated with hypertension and described in the literature as a cause of secondary diabetes mellitus. In patients with known persistent uncontrolled diabetes, PHEO is rarely mentioned as the cause of uncontrolled diabetes. The authors report a rare case of PHEO diagnosed in a 64-year-old female patient treated for 10 years with type 2 diabetes mellitus and hypertension. She was treated using a combination of insulin (2 injections) and Metformin 1000 mg twice a day. The glycemic control was poor (HbA1c-11%), and persistent High Blood Pressure (HBP). She presented with unexplained weight loss associated with permanent hyperhidrosis (sweating), affecting her quality of life and diffuse abdominal pain. The investigations confirmed the diagnosis of PHEO, which resection led to improvement of glycemic control and hypertension.展开更多
The digital transformation in Cameroon presents critical cybersecurity challenges that demand immediate attention and strategic intervention. This comprehensive analysis examines the evolving cybersecurity landscape i...The digital transformation in Cameroon presents critical cybersecurity challenges that demand immediate attention and strategic intervention. This comprehensive analysis examines the evolving cybersecurity landscape in Cameroon from 2020 to 2023, during which cyber-attacks increased by 156% and financial losses from digital fraud exceeded $45 million. This research identifies significant vulnerabilities in Cameroon’s cybersecurity ecosystem through a rigorous assessment of national infrastructure, policy frameworks, and institutional capacities. Recent data indicates that while digital service adoption has grown exponentially, with internet penetration reaching 35.2% in 2023, cybersecurity measures have lagged significantly behind international standards. This analysis draws on comprehensive data from multiple sectors, including financial services, government institutions, and telecommunications, incorporating findings from the National Cybersecurity Assessment Program and the Digital Infrastructure Security Report. The research reveals that 73% of organizations lack dedicated security teams, while response times to cyber incidents average 72 hours—three times than the global standard. Based on these findings, this paper proposes evidence-based solutions for enhancing digital resilience, including policy modernization, capacity-building initiatives, and technical infrastructure development. The recommendations encompass short-term tactical responses, medium-term strategic improvements, and long-term structural changes, providing a comprehensive roadmap for strengthening Cameroon’s national cybersecurity frameworks.展开更多
In order to contribute to a better understanding of the biodiversity of local chicken populations, this study focused on the description of the essential qualitative parameters in the phenotypic characterization of lo...In order to contribute to a better understanding of the biodiversity of local chicken populations, this study focused on the description of the essential qualitative parameters in the phenotypic characterization of local species. Conducted in 6 localities in the Far North Region of Cameroon (Doukoula, Yagoua, Guidiguis, Dziguilao, Maroua 3rd and Méri), a population of 240 local chickens, including 172 hens and 68 cocks were characterized in family farms. The choice of localities was made on the basis of their strong potential local chicken flocks in the region. To this end, each animal was the subject of a qualitative description based on the identification of the sex of the animal, the description of the colorations of the plumage and extremities, and the description of the types of format, plumage and crests. All observations were made with the naked eye and in daylight and then photographed. The main results show that the plumage colors are multiple and dominated by the White-Pied-Black (21.7%) and the Mille-fleur (20.8%);the wattles are dominated by the red (60%) and the pink (35.4%);the tarsi are dominated by the white (43.8%) and the black (32.08%);the white skin (92.5%) dominates over the pink skin (7.5%);the “Smooth-uniform” feather is dominant (97.08%), followed by the smooth-crested type (2.08%) and the fries type (0.82%);the medium size of the chickens is dominant (86.66%), followed by the dwarf size (9.58%) and the large size (3.75%). The results of this study demonstrate that there is a strong phenotypic diversity within the local chicken population. This diversity can serve as a basis for the development of selection, conservation and genetic potential improvement programs based on rational exploitation of the local chicken.展开更多
Existing knowledge on degraded mountain landscapes does not shed sufficient light on the socio-economic and ecological opportunities essential for successful restoration initiatives.To address this knowledge lacuna,a ...Existing knowledge on degraded mountain landscapes does not shed sufficient light on the socio-economic and ecological opportunities essential for successful restoration initiatives.To address this knowledge lacuna,a study was conducted on the Bamboutos Mountains landscape in Cameroon with the main objective being to analyse the opportunities for restoring this landscape in line with local,national and international development goals and to minimise the negative effects of land-use decisions.Following the Restoration Opportunity Assessment Methodology(ROAM)approach,five participatory reflection workshops were organized in the five target clusters of the landscape for data collection.The results of the study led to the development of a restoration map that presents five interventions:grassland management on an area of 4,720 ha currently occupied by shrub savannah;the practice of fruit-based agroforestry on 3,221 ha of agricultural fields;the planting of riparian forests on 451 ha of degraded watercourses;the revegetation and conservation of the Bamboutos Mountains forest reserve,sacred forests and relics of degraded forests on 435 ha of area;and the revegetation of 6 ha of degraded water sources.The carbon stocks vary from 2.66 to 345.15 tC/ha depending on the type of restoration intervention with a total carbon stock of 247,367.45 tC/ha on the 8,834 ha of area to be restored.This presents a very satisfactory economic cost-benefit,because for an investment of USD 5,991,269.84,a gain of USD 100,439,519.13 could be achieved after 20 years,i.e.,an estimated profit of USD 94,448,249.29.These results provide an understanding of the types of restoration interventions possible in this landscape,a solid basis for planning a restoration initiative.The results equally provide guidance on priority areas from a social,economic,and ecological perspective.展开更多
BACKGROUND The global prevalence of diabetes among adults aged 29-79 years was found to be 10.5%.It is a global public health threat with a rising trend in morbidity and mortality.Poor glycemic control(GC)among patien...BACKGROUND The global prevalence of diabetes among adults aged 29-79 years was found to be 10.5%.It is a global public health threat with a rising trend in morbidity and mortality.Poor glycemic control(GC)among patients with type 2 diabetes mellitus(T2DM)is a major determinant of diabetes-related complications.There are limited data on GC and associated factors among patients with T2DM in South West Region,Cameroon.AIM To assess GC and identify contributing factors among patients with T2DM in a regional hospital in South West Region,Cameroon.METHODS A cross-sectional study was conducted from February 2022 to July 2022 among 131 participants in Limbe Regional Hospital who were selected by convenience.Glycated hemoglobin(HbA1c)was measured by ion-exchange chromatography.Sociodemographic,clinical,and lifestyle data were collected,entered into Excel,and exported to Statistical Package for Social Sciences version 22 for analysis.A multivariate logistic regression analysis was conducted to assess the association between explanatory variables and GC.The level of significance was set at P<0.05.RESULTS The mean age was 56±5.1 years.Eighty-eight(67.2%)patients were female.The mean HbA1c was 8.8%±1.8%.Poor GC(HbA1c≥7%)was registered in 106(80.9%;95%confidence interval:73.1%-87.3%)participants.Lack of self-monitoring of blood glucose at home was associated with poor GC(adjusted odds ratio:3.858,95%confidence interval:1.262-11.800;P=0.018).CONCLUSION The majority of patients with T2DM had poor GC.Absence of self-monitoring of blood glucose at home was the main contributing factor for poor GC.展开更多
Sacred forests play a valuable role in the conservation of local biodiversity and provide numerous ecosystem services in Cameroon. The aim of this study was to estimate floristic diversity, stand structures and carbon...Sacred forests play a valuable role in the conservation of local biodiversity and provide numerous ecosystem services in Cameroon. The aim of this study was to estimate floristic diversity, stand structures and carbon stocks in the sacred forests of Bandrefam and Batoufam (western Cameroon). The floristic inventory and the stand structures were carried out in 25 m × 25 m plots for individuals with diameters greater than 10 cm;5 m × 5 m for individuals with diameters less than 10 cm. Carbon stocks were estimated using the non-destructive method and allometric equations. The floristic inventory identified 65 species divided into 57 genera and 30 families in the Bandrefam sacred forest and 45 species divided into 42 genera and 27 families in the Batoufam sacred forest. In the Bandrefam, the most important families are Phyllanthaceae (53.98%), Moraceae (21.69%), Lamiaceae (20.15%). At Batoufam, the most important families are Phyllanthaceae (39.73%), Fabaceae (28.47%), Araliaceae (23.77%). Malacantha alnifolia (55.14%), Vitex grandifolia (18.43%), Bosqueia angolensis (15.06%) were the most important species in Bandrefam. Otherwise, Malacantha alnifolia (28%), Polyscias fulva (22.73%), Psychotria sp. (21.28%) were the most important in Batoufam. The Bandrefam sacred forest has the highest tree density (2669 stems/ha). Total carbon stock is 484.88 ± 2.28 tC/ha at Batoufam and 313.95 ± 0.93 tC/ha at Bandrefam. The economic value varies between 5858.04 ± 27.62 USD/ha in Batoufam sacred forest and 3788.51 ± 11.26 USD/ha in Bandrefam sacred forest. The number of individuals and small-diameter trees has little influence on the carbon stocks in the trees. Medium-diameter trees store the most carbon, and very large-diameter trees, which are very poorly represented, store less carbon. In another way, wood density and the basal areas influence the carbon storage of the trees.展开更多
The REE signature of banded iron formations (BIF) and martite-goethite mineralization of the Njweng ridge (South Cameroon) are used here to decipher the nature of the ocean during the period of BIF precipitation. The ...The REE signature of banded iron formations (BIF) and martite-goethite mineralization of the Njweng ridge (South Cameroon) are used here to decipher the nature of the ocean during the period of BIF precipitation. The textures of typical BIF categories are also presented as the only sedimentary feature. Two types of BIF facies are present at Njweng: the oxide and silicate facies. These facies show two stages of phase transformations. The first is the transformation of the original magnetite mineral into martite by oxidation resulting in trellis texture;the second is a simultaneous transformation by hydration into goethite and dehydration into martite. The samples typically show LREE depleted patterns relative to HREE, a characteristic similar to that of modern seawater. Also the strong positive Eu anomalies from the samples indicate the involvement of hydrothermal plumes of volcanic origin such as at mid ocean ridges (MOR). Yttrium (Y) has a strong positive anomaly pointing to the transportation of REEs as aqueous complexes within these ancient seas. The BIF samples have no positive Ce anomalies, suggesting that the oceans at that time were more reducing with no Ce fractionation than in present day oceans. The martite-goethite mineralization rather shows a positive Ce anomaly that derived from the enrichment in REE during the weathering of REE-bearing minerals. These results are integrated into existing literature on REE in BIFs worldwide and provide new insights into these heretofore unstudied BIFs of the northern edge of the Congo Craton.展开更多
Three monogenetic cones in the Baossi–Warack area, Ngaoundéré, Adamawa Plateau forming part of the Cameroon Volcanic Line(CVL) are documented in this study. Basaltic lavas(<1 km^3) scattered around these...Three monogenetic cones in the Baossi–Warack area, Ngaoundéré, Adamawa Plateau forming part of the Cameroon Volcanic Line(CVL) are documented in this study. Basaltic lavas(<1 km^3) scattered around these vents and restricted volcaniclastic deposits were emplaced by Hawaiian and mild strombolian style eruptions. The lavas are porphyritic, mainly composed of olivine(chrysolite) and clinopyroxene(diopside and augite) phenocrysts and plagioclase(andesine) microphenocrysts. Accessory minerals include titano-magnetite and titano-hematite, nepheline,apatite and amphibole xenocrysts. Sanidine occurs in some samples and sodi-potassic albite in others. Some olivines and clinopyroxenes exhibit resorbed margins and thin reaction rims while plagioclase displays oscillatory zoning, and sieved textures as a result of magma mixing. Whole-rock geochemistry data indicates that the lavas are silica-undersaturated, composed of basanites and basalts, showing little compositional variations(SiO_2: 39.20 wt.%–48.01 wt.%,MgO: 5.29 wt.%–9.70 wt.%). Trace elements patterns of these lavas suggest they are enriched in LILE including Pb,probably due to crustal contamination. REE patterns suggest cogenetic magmas below Baossi 1 and Baossi 2 volcanoes,and distinct sources below Warack volcano and nearby lavas.The lavas studied show affinity to high-μ(HIMU), enriched type Ⅰ(EM1) and Oceanic Island Basalt(OIB)-like mantle signatures and thus indicate a heterogeneous mantle source underneath the vents as noted at other monogenetic and polygenetic volcanoes along the CVL. Primary melts derived from low degrees of partial melting(0.5%–2%) and encountered low rates of fractionation, and crustal contamination coupled with magma mixing. These melts evolved independently through structural weaknesses in the basement.展开更多
Exploration for primary gold in tropical settings is often problematic because of deep weathering and the development of a thick soil cover. In this paper we present the results of both chargeability and resistivity s...Exploration for primary gold in tropical settings is often problematic because of deep weathering and the development of a thick soil cover. In this paper we present the results of both chargeability and resistivity surveys carried out over the Belikombone hill gold prospect (14?00' - 14?25'E, 5?25' - 6?00'N) in the Betare Oya area (eastern Cameroon), where previous soil sampling had identified gold anomalies. The geophysical data were obtained using Syscal Junior 48 resistivity meter and the Schlumberger configuration array for both the vertical electrical soundings (VES) and horizontal profiling. These data were further built into a GIS framework and the continuity of favourable gold-bearing structures at depth modeled using WINSEV, RED2INV and SURFER extensions softwares. IP (Induced Polarization)-chargeability and resistivity data combined, have identified irregular anomalous zones trending NE-SW. This trend is consistent with the attitude of most auriferous quartz veins exposed in artisanal pits and parallel to the regional shear zone system and foliations. The high resistivity anomalies correspond to quartz veins while the relatively high IP anomalies correspond to low sulphide ± gold concentrations in the quartz veins. Modeling IP-chargeability and resistivity data prepared as contours and 3D maps, culminated to the development of an inferred, irregular and discontinuous mineralized body at depths of up to 95 m. The size and shape of this mineralized body can only later be tested by drilling to ascertain the resource.展开更多
We used the Earth Gravitational Model （EGM2008） data sets to analyze the regional gravity anoma- lies and to study the underground structures in Cameroon. We first created a high-resolution Free-Air anomaly database...We used the Earth Gravitational Model （EGM2008） data sets to analyze the regional gravity anoma- lies and to study the underground structures in Cameroon. We first created a high-resolution Free-Air anomaly database, then corrected the gravity field of the topographic effect by using ETOPO1 DEM with a resolution of 0.01~ to obtain the Bouguer anomaly, then applied a multi-scale wavelet-analysis technique to separate the gravity-field components into different parts of shallow-to-deep origins, and finally used the logarithmic power spectrum technique to obtain detailed images and corresponding source depths as well as certain lateral inho- mogeneity of structure density. The anomalies of shallow origin show successive elongated gravity ＂highs＂ and ＂lows＂ attributable to subsurface Tertiary and lower Cretaceous undulations. Our results are in good agreement with previous investigations.展开更多
Bioko Island（3008 m a.s.l） is located in the presently more active volcanic zone of the Cameroon Line and composed essentially of alkaline basalts and hawaiites, and lesser mugearites. The rocks show microlitic porp...Bioko Island（3008 m a.s.l） is located in the presently more active volcanic zone of the Cameroon Line and composed essentially of alkaline basalts and hawaiites, and lesser mugearites. The rocks show microlitic porphyritic texture with phenocrysts of olivine（83% 〈 Fo 〈 87%） and clinopyroxene in a matrix of plagioclase, clinopyroxene and oxides. Hawaiites and mugearites also include phenocrysts of plagioclase（An62-67Ab35-32Or3-1）. Major element variation diagrams show an increase in Si O2, Al2O3, Na2 O and K2 O with increasing Mg O for the studied rock groups. The rocks are characterized by low（^86Sr/^87Sr）i ratios（0.70320e0.70406）, high 3Nd（t） values（2.56e4.33） and high（^206Pb/^204Pb）i ratios（20.032e20.035） values.Basalts are enriched in LILE and LREE, and have（Hf/Sm）N= 0.57e1.16. These geochemical signatures are similar to those of the Mount Cameroon rocks, and might be attributed to low degrees of partial melting from a garnet-amphibole-bearing mantle source. The trace elements and isotopic compositions suggest that the parental magma source might have involved HIMU- and EM1-components.展开更多
Geophysical and geotechnical surveys were conducted in the Western Cameroon (Kekem area) following a landslide on argillaceous material in order to understand the triggering processes and mechanisms of this landslide ...Geophysical and geotechnical surveys were conducted in the Western Cameroon (Kekem area) following a landslide on argillaceous material in order to understand the triggering processes and mechanisms of this landslide and to assess the stability of the slope. The geophysical soundings consisting of vertical electrical soundings with the Schlumberger electrode array configuration were carried out to monitor the behaviour of electrical resistivity in the landslide. Geoelectrical data showed a zone of low resistivity values identified as a clayey sand-filled aquifer. This aquifer played an important role in the triggering process of the landslide. Geotechnical soundings showed that the aquifer had a thickness of 7.0 m. The depth from the landslide crest level to the failure surface reached 3.0 m and 20.6 m. Laboratory tests were then carried out in order to evaluate the cohesion of the soil and the angle of internal friction, and to calculate the safety factor in view of making a stability analysis. The laboratory results exhibited a soil with low consistency, almost doughy. The mean value of the safety factor (1.4) been lower than the slope stability coefficient (1.5), revealed that the slope is unstable, likely to know at any moment a reactivation of the slide. This study showed that electrical soundings coupled with geotechnical surveys are useful tools for the characterization of landslides.展开更多
Mapping and documentation of lithological varieties and their corresponding geochemistry at the Kitongo uranium mineralization were concerned. The Kitongo U occurrence is hosted by granitic rocks that include interlea...Mapping and documentation of lithological varieties and their corresponding geochemistry at the Kitongo uranium mineralization were concerned. The Kitongo U occurrence is hosted by granitic rocks that include interleaved sequences of metasedimentary and metavolcanic rocks of the collectively termed Poli Group. U-mineralization and Na-metasomatism are related and structurally controlled. The most promising uraniferous bodies are intimately related to intersections between the ductile ENE-trending faults and the brittle conjugate R' faults postdating the shearing event. The con- centration of uranium at fault intersections rather than along individual faults suggests that these zones that are dilatational in nature were also highly permeable and therefore the hydrothermal fluids ponded there could readily precipitate U therein. A two-stage albitization has altered the foliated granitic host rock and the second albitization that has over-printed the first one is more effective at fault intersections. Whole rock geochemistry was performed by using ICP-MS and ICP-AES respectively for major oxides, trace and REE. The U-bearing rock suite exhibits restricted range in SiO2 concentration (62.89% - 70.91%) and Al2O3 (13.16% - 18.59%) and it is poor in MgO (0.02% - 1.03%), CaO (0.24% - 1.88%) and K2O (0.08% - 5.32%). The mineralized rocks are however comparatively richer in Na2O (4.33% - 10.92%) compared to their barren counterparts. The host granite and associated granodioritic rocks in the area are weakly metaluminous, peralkaline, and are calc-alkaline. They are moderately to strongly fractionated and have tholeiitic and shoshonitic affinities with moderate to high HFSE (high field strength elements) and LILE (large ion lithophile elements) enrichment. The Rb/Sr, Rb/Ba and Sr/Ba ratios are 0.31, 0.14 and 1.48, respectively. U content in the mineralized granite is up to 651 ppm while the non-mineralized rock has only 2.4 ppm U. The REE patterns of the granite show LREE enrichment and strong Eu negative anomalies (Eu/Eu* = 0.03 to 0.48). The main mineralization stage characterized by local U, Na, Pb, Zn, Ga, Hf, Sr, Fe, Al, P and Zr enrichments is related to the second albitization event and could probably be associated in time with the calcite-uranium stage. The identification of fault segments favorable for uranium mineralization in northern Cameroon (Poli area) is important for understanding the genesis of hydrothermal ore deposits within continental strike-slip faults and therefore has great implications for exploration strategies.展开更多
In Douala, economic capital of Cameroon, annual rainfall and temperature from its meteorological station (latitude: 4o00'N;longitude: 9o43'E;elevation: 5.0 m) were obtained and analysed to investigate the impa...In Douala, economic capital of Cameroon, annual rainfall and temperature from its meteorological station (latitude: 4o00'N;longitude: 9o43'E;elevation: 5.0 m) were obtained and analysed to investigate the impact of climate variability on groundwater recharge. The climate shows a strong evidence of changes towards persistent weather conditions. The region is mainly characterized by a mean inter-annual temperature of 27.4oC and influenced by the mount Cameroon (4095 m in elevation). A recent decrease in mean annual rainfall occurred since 1982. The average annual rainfall which was 4200 mm with about 220 days of rainfall from 1917 to 1937 has moved to 4049 mm for the period 1937-1957, to 3826 mm for the period 1968-1988 and to 3619 mm for the period 1971-2001. Between, 1997 and 2007, the total number of days of rainfall has not exceeded 220 (193 days of rainfall in 1998 and 216 days of rainfall in 1999). By using Gauss law on 31 years (1971-2001) of annual rainfall, one note that the value 2850 mm has 20% of luck to be not observed and the value 4219 mm has 20% of luck to be exceeded. Douala already suffers from water shortage not because of decrease of rainfall but due to quality of underground water and salty taste of the main river catched for water supply. Moreover, precipitation is considered as the main replenishment source of all water resources in the study area (watershed of Besseke). The calculated interannual groundwater recharge rate (potential recharge, not necessarily real) is about 9% compared to the interannual total precipitation received by this area located closer the Atlantic Ocean (Gulf of Guinea). Groundwater discharge from the aquifer occurs between November and March.展开更多
Up to date, tropical mountainous ecosystems still lack in depth information on soil and environmental characteristics which are major factors limiting optimum crop production. The objective of this work was to study s...Up to date, tropical mountainous ecosystems still lack in depth information on soil and environmental characteristics which are major factors limiting optimum crop production. The objective of this work was to study soil characteristics and to evaluate the land capability level for the production of some common tropical crops in mountainous ecosystem soils of North West Cameroon. Soil sampling was done following a randomized complete block design (RCBD) with four replications for three topographic positions (upslope, midslope and footslope) and at two depths (0 - 20 cm and 20 - 100 cm). It was completed by standard laboratory analyses. The fertility capability classification (FCC) system enabled to identify soil limitations and to classify soils into FCC units. Land and climate were evaluated by simple limitation and parametric methods. Globally, the soils were dark-colored, sandy clayey to clayey, compact and very acidic (pHH2O = 4.3 - 5.8). The organic matter (3.7% - 5.1% dry matter), total nitrogen (0.08% - 0.56%) and available phosphorus (22.1 to 30.9 mg?kg?1) recorded for the 0 - 20 cm depth then reduced with depth but midslope values were also lower. The C/N ratio varied between 9 and 45. Low C/N values appeared mostly in 0 - 20 cm depth at the upslope and downslope soils and subsurface soils of midslope position. Exchangeable Ca was very low to low (1.43 - 3.6 cmol + kg?1), Mg was very low to low (0.39 - 1.5 cmol + kg?1), K was low to medium (0.2 - 0.54 cmol + kg?1) and Na was very low (?1). The sum of exchangeable bases was very low (3.02 - 5.19 cmol + kg?1), cation exchange capacity was low to moderate (8.60 - 25.6 cmol + kg?1) and base saturation was very low to low (19.27% - 36.97%). Leaching of bases under heavy rainfall is a major cause of soil acidification under humid topical ecosystems. The Ca/Mg/K ratio was unbalanced and Mg was the most relatively concentrated base in all the soils. There was a clear variation of most of the soil properties along the slope and with depth. The soils were classified in the FCC system as aek for the upslope soils, Caek for the midslope soils and Cagk for the footslope soils. The principal limitations to production of huckleberry, beans, maize and potatoes were heavy rainfall, wetness, steep slope, soil texture/structure and low soil fertility. These constraints might be overcome by farming at the end of the raining season, contour ploughing, terracing, fertilization and liming.展开更多
Stream sediment geochemistry remains a versatile tool in exploration especially in regions where knowledge of the primary mineralization is lacking and the exploration activities are still at reconnaissance stage. In ...Stream sediment geochemistry remains a versatile tool in exploration especially in regions where knowledge of the primary mineralization is lacking and the exploration activities are still at reconnaissance stage. In this study, we investigate the concentrations of gold and associated elements in stream sediment samples from the Vaimba-Lidi drainage system in northern Cameroon;a relatively remote area where alluvial gold is worked locally, and exploration activities are at early stage. The main river and its principal first and second order tributaries were sampled, panned for gold grain recovery and the 100 μm size fraction analyzed for Au by fire assay with Ni finish. A suite of other elements were analyzed for by inductively coupled plasma mass spectrometry (ICP-MS). Gold grades estimated by the panning and weighing technique rarely exceed1 g/t while the Au concentrations from chemical analysis range from 3.0 to 354.0 ppm. The spatial distribution of gold and all the other elements are presented as point symbol maps and the data analyzed using multivariate statistics. From the principal component analysis (PCA), the As-Mo-W-Ag as well as the Au-Zn factors point to the presence of primary hydrothermal gold-sulphide mineralization in the area and this can be further investigated. These results highlight the importance of multielement analysis and multivariate statistical interpretation of sediment geochemical data in inferring the nature of the underlying primary mineralization in any region.展开更多
In Cameroon, despite extensive control efforts against HIV/AIDS, the number of new HIV infections is still on the rise. The factors contributing to this are not clearly understood. We hypothesized that it may lie on p...In Cameroon, despite extensive control efforts against HIV/AIDS, the number of new HIV infections is still on the rise. The factors contributing to this are not clearly understood. We hypothesized that it may lie on people living with HIV (PLHIV). In a case-control descriptive study, we studied the characteristics and sexual risky behaviour of PLHIV in the North West Region of Cameroon which has the highest HIV prevalence. Participants were screened for HIV and a structured questionnaire was used in data collection. An equivalent number (350) of PLHIV and controls who did not differ with respect to age and sex participated. Relative to the control, PLHIV were generally less educated (P < 0.001), poorer and less privileged (P < 0.001) with no stable source of income. Among participants that were once married, a greater proportion of PLHIV were divorced (OR = 5.23, P = 0.007), and widows (OR = 2.73, P = 0.001). Among participants that were single, a relatively greater proportion of PLHIV practiced multi-partner sex (OR = 4.55, P< 0.001). History of STDs was higher in PLHIV than the control (OR = 1.88, P = 0.001). Out of 350 PLHIV, 280 (80%) admitted to having had sexual intercourse after being diagnosed of which only 127 (41.78%) admitted to using condoms and 132 (47.14%) admitted to concealing their HIV status from their sexual partner(s). These findings have implications in HIV control programs which should target the poor and the less educated, as well as the sexual behaviour of PLHIV, so as to reverse the current rising trend of new infections in the country.展开更多
Iron ore deposits hosted by Precambrian banded iron formation(BIF)are the most important source of mineable iron.In Cameroon,they are located in the southern part of the country.This study reports the petrological and...Iron ore deposits hosted by Precambrian banded iron formation(BIF)are the most important source of mineable iron.In Cameroon,they are located in the southern part of the country.This study reports the petrological and geochemical data of iron ores collected from a weathering profile in the Mamelles BIF deposit,SW Cameroon.The profile is composed of three levels which are from the bottom to the top:the saprock,the ferruginous horizon,and the loose horizon.Eight representative iron ore samples(rock fragments and loose clayey material)were collected along the profile and were subjected to petrographic and geochemical analyses.Their mineralogy consists of martite,goethite,quartz,and lesser amounts of hematite,magnetite,kaolinite,and halloysite.The presence of minerals such as kaolinite and goethite in the Mamelles iron ores suggests their supergene origin.Geochemically,the saprock is characterized by high iron content(70.25 wt%Fe_(2)O_(3) t),and low silica(26.38 wt%SiO_(2))and alumina(1.14 wt%Al_(2) O_(3)).The rock fragments collected from the ferruginous horizon display higher Fe2 O3 t(72-76.40 wt%),Al_(2) O_(3)(2.80-5.43 wt%),and lower SiO_(2)(16.70-18.35 wt%)contents,suggesting the leaching of silica during the enrichment process.The loose clayey samples collected from both the ferruginous horizon and the upper loose horizon show lower iron and higher silica contents.When normalized to the underlying BIF saprock,both rock fragments and loose clayey ores display LREE enrichment,suggesting that they formed through supergene processes.Economically,most of the Mamelles iron ores are classified as medium-grade ores and a few display acceptable contents in contaminants.Overall,this petrological and geochemical study of the Mamelles iron ores revealed encouraging results.Given its strategic location near the deep seaport,the deposit should be investigated in more detail for its mining potential.展开更多
Forest logging in the Congo Basin has led to forest fragmentation due to logging infrastructures and felling gaps. In the same vein, forest concessions in the Congo Basin have increasing interest in the REDD＋ mechani...Forest logging in the Congo Basin has led to forest fragmentation due to logging infrastructures and felling gaps. In the same vein, forest concessions in the Congo Basin have increasing interest in the REDD＋ mechanism. However, there is little information or field data on carbon emissions from forest degradation caused by logging. To help fill this gap, Landsat 7 and 8 and SPOT 4 images of the East Region of Cameroon were processed and combined with field measurements （measurement of forest roads widths, felling gaps and log yards） to assess all disturbed areas. Also, measurements of different types of forest infrastructures helped to highlight emission factors. Forest contributes to 5.18 % of the degradation of the annual allowable cut （AAC） （84.53 ha） corresponding to 4.09 % of forest carbon stock （6.92 t ha^-1）. Felling gaps constitute the primary source of degradation, represented an estimated area of 32.41 ha （2 % of the cutting area） far ahead of primary roads （18.44ha） and skid trails （16.36 ha）. Assessment of the impact of degradation under the canopy requires the use of high resolution satellite images and field surveys.展开更多
AIM:Gallstone disease is increasing in sub-saharan Africa (SSA).In the west, the majority of stones can be dissolved with bile salts,since the major component is cholesterol.This medical therapy is expensive and not r...AIM:Gallstone disease is increasing in sub-saharan Africa (SSA).In the west, the majority of stones can be dissolved with bile salts,since the major component is cholesterol.This medical therapy is expensive and not readily accessible to poor populations of SSA.It was therefore necessary to analyze the chemical composition of biliary stones in a group of patients,so as to make the case for introducing bile salt therapy in SSA.METHODS: All patients with symptomatic gallstones were recruited in the study. All stones removed during cholecystectomy were sent to Houston for x-ray diffraction analysis.Data on age, sex, serum cholesterol,and thepercentage by weight of cholesterol, calcium carbonate, and amorphous material in each stone was entered into a preestablished proforma. Frequencies of the major components of the stones were determined.RESULTS:Sixteen women and ten men aged between 27 and 73 (mean 44.9) years provided stones for the study.The majority of patients (65.38%) had stones with less than 25% of cholesterol.Amorphous material made up more than 50% and 100% of stones from 16 (61.53%) and 9 (34.61%) patients respectively.CONCLUSION:Cholesterol is present in small amounts in a minority of gallstones in Yaounde. Dissolution of gallstones with bile salts is unlikely to be successful.展开更多
文摘Pheochromocytoma (PHEO) is a rare endocrine tumor from the chromaffin cells in the adrenomedullary gland and sympathetic/parasympathetic ganglia, secreting one or more catecholamines. It is frequently associated with hypertension and described in the literature as a cause of secondary diabetes mellitus. In patients with known persistent uncontrolled diabetes, PHEO is rarely mentioned as the cause of uncontrolled diabetes. The authors report a rare case of PHEO diagnosed in a 64-year-old female patient treated for 10 years with type 2 diabetes mellitus and hypertension. She was treated using a combination of insulin (2 injections) and Metformin 1000 mg twice a day. The glycemic control was poor (HbA1c-11%), and persistent High Blood Pressure (HBP). She presented with unexplained weight loss associated with permanent hyperhidrosis (sweating), affecting her quality of life and diffuse abdominal pain. The investigations confirmed the diagnosis of PHEO, which resection led to improvement of glycemic control and hypertension.
文摘The digital transformation in Cameroon presents critical cybersecurity challenges that demand immediate attention and strategic intervention. This comprehensive analysis examines the evolving cybersecurity landscape in Cameroon from 2020 to 2023, during which cyber-attacks increased by 156% and financial losses from digital fraud exceeded $45 million. This research identifies significant vulnerabilities in Cameroon’s cybersecurity ecosystem through a rigorous assessment of national infrastructure, policy frameworks, and institutional capacities. Recent data indicates that while digital service adoption has grown exponentially, with internet penetration reaching 35.2% in 2023, cybersecurity measures have lagged significantly behind international standards. This analysis draws on comprehensive data from multiple sectors, including financial services, government institutions, and telecommunications, incorporating findings from the National Cybersecurity Assessment Program and the Digital Infrastructure Security Report. The research reveals that 73% of organizations lack dedicated security teams, while response times to cyber incidents average 72 hours—three times than the global standard. Based on these findings, this paper proposes evidence-based solutions for enhancing digital resilience, including policy modernization, capacity-building initiatives, and technical infrastructure development. The recommendations encompass short-term tactical responses, medium-term strategic improvements, and long-term structural changes, providing a comprehensive roadmap for strengthening Cameroon’s national cybersecurity frameworks.
文摘In order to contribute to a better understanding of the biodiversity of local chicken populations, this study focused on the description of the essential qualitative parameters in the phenotypic characterization of local species. Conducted in 6 localities in the Far North Region of Cameroon (Doukoula, Yagoua, Guidiguis, Dziguilao, Maroua 3rd and Méri), a population of 240 local chickens, including 172 hens and 68 cocks were characterized in family farms. The choice of localities was made on the basis of their strong potential local chicken flocks in the region. To this end, each animal was the subject of a qualitative description based on the identification of the sex of the animal, the description of the colorations of the plumage and extremities, and the description of the types of format, plumage and crests. All observations were made with the naked eye and in daylight and then photographed. The main results show that the plumage colors are multiple and dominated by the White-Pied-Black (21.7%) and the Mille-fleur (20.8%);the wattles are dominated by the red (60%) and the pink (35.4%);the tarsi are dominated by the white (43.8%) and the black (32.08%);the white skin (92.5%) dominates over the pink skin (7.5%);the “Smooth-uniform” feather is dominant (97.08%), followed by the smooth-crested type (2.08%) and the fries type (0.82%);the medium size of the chickens is dominant (86.66%), followed by the dwarf size (9.58%) and the large size (3.75%). The results of this study demonstrate that there is a strong phenotypic diversity within the local chicken population. This diversity can serve as a basis for the development of selection, conservation and genetic potential improvement programs based on rational exploitation of the local chicken.
基金the material and logistical support provided by the Environmental Geomatics Laboratory of the Forestry Department of the University of Dschang
文摘Existing knowledge on degraded mountain landscapes does not shed sufficient light on the socio-economic and ecological opportunities essential for successful restoration initiatives.To address this knowledge lacuna,a study was conducted on the Bamboutos Mountains landscape in Cameroon with the main objective being to analyse the opportunities for restoring this landscape in line with local,national and international development goals and to minimise the negative effects of land-use decisions.Following the Restoration Opportunity Assessment Methodology(ROAM)approach,five participatory reflection workshops were organized in the five target clusters of the landscape for data collection.The results of the study led to the development of a restoration map that presents five interventions:grassland management on an area of 4,720 ha currently occupied by shrub savannah;the practice of fruit-based agroforestry on 3,221 ha of agricultural fields;the planting of riparian forests on 451 ha of degraded watercourses;the revegetation and conservation of the Bamboutos Mountains forest reserve,sacred forests and relics of degraded forests on 435 ha of area;and the revegetation of 6 ha of degraded water sources.The carbon stocks vary from 2.66 to 345.15 tC/ha depending on the type of restoration intervention with a total carbon stock of 247,367.45 tC/ha on the 8,834 ha of area to be restored.This presents a very satisfactory economic cost-benefit,because for an investment of USD 5,991,269.84,a gain of USD 100,439,519.13 could be achieved after 20 years,i.e.,an estimated profit of USD 94,448,249.29.These results provide an understanding of the types of restoration interventions possible in this landscape,a solid basis for planning a restoration initiative.The results equally provide guidance on priority areas from a social,economic,and ecological perspective.
文摘BACKGROUND The global prevalence of diabetes among adults aged 29-79 years was found to be 10.5%.It is a global public health threat with a rising trend in morbidity and mortality.Poor glycemic control(GC)among patients with type 2 diabetes mellitus(T2DM)is a major determinant of diabetes-related complications.There are limited data on GC and associated factors among patients with T2DM in South West Region,Cameroon.AIM To assess GC and identify contributing factors among patients with T2DM in a regional hospital in South West Region,Cameroon.METHODS A cross-sectional study was conducted from February 2022 to July 2022 among 131 participants in Limbe Regional Hospital who were selected by convenience.Glycated hemoglobin(HbA1c)was measured by ion-exchange chromatography.Sociodemographic,clinical,and lifestyle data were collected,entered into Excel,and exported to Statistical Package for Social Sciences version 22 for analysis.A multivariate logistic regression analysis was conducted to assess the association between explanatory variables and GC.The level of significance was set at P<0.05.RESULTS The mean age was 56±5.1 years.Eighty-eight(67.2%)patients were female.The mean HbA1c was 8.8%±1.8%.Poor GC(HbA1c≥7%)was registered in 106(80.9%;95%confidence interval:73.1%-87.3%)participants.Lack of self-monitoring of blood glucose at home was associated with poor GC(adjusted odds ratio:3.858,95%confidence interval:1.262-11.800;P=0.018).CONCLUSION The majority of patients with T2DM had poor GC.Absence of self-monitoring of blood glucose at home was the main contributing factor for poor GC.
文摘Sacred forests play a valuable role in the conservation of local biodiversity and provide numerous ecosystem services in Cameroon. The aim of this study was to estimate floristic diversity, stand structures and carbon stocks in the sacred forests of Bandrefam and Batoufam (western Cameroon). The floristic inventory and the stand structures were carried out in 25 m × 25 m plots for individuals with diameters greater than 10 cm;5 m × 5 m for individuals with diameters less than 10 cm. Carbon stocks were estimated using the non-destructive method and allometric equations. The floristic inventory identified 65 species divided into 57 genera and 30 families in the Bandrefam sacred forest and 45 species divided into 42 genera and 27 families in the Batoufam sacred forest. In the Bandrefam, the most important families are Phyllanthaceae (53.98%), Moraceae (21.69%), Lamiaceae (20.15%). At Batoufam, the most important families are Phyllanthaceae (39.73%), Fabaceae (28.47%), Araliaceae (23.77%). Malacantha alnifolia (55.14%), Vitex grandifolia (18.43%), Bosqueia angolensis (15.06%) were the most important species in Bandrefam. Otherwise, Malacantha alnifolia (28%), Polyscias fulva (22.73%), Psychotria sp. (21.28%) were the most important in Batoufam. The Bandrefam sacred forest has the highest tree density (2669 stems/ha). Total carbon stock is 484.88 ± 2.28 tC/ha at Batoufam and 313.95 ± 0.93 tC/ha at Bandrefam. The economic value varies between 5858.04 ± 27.62 USD/ha in Batoufam sacred forest and 3788.51 ± 11.26 USD/ha in Bandrefam sacred forest. The number of individuals and small-diameter trees has little influence on the carbon stocks in the trees. Medium-diameter trees store the most carbon, and very large-diameter trees, which are very poorly represented, store less carbon. In another way, wood density and the basal areas influence the carbon storage of the trees.
文摘The REE signature of banded iron formations (BIF) and martite-goethite mineralization of the Njweng ridge (South Cameroon) are used here to decipher the nature of the ocean during the period of BIF precipitation. The textures of typical BIF categories are also presented as the only sedimentary feature. Two types of BIF facies are present at Njweng: the oxide and silicate facies. These facies show two stages of phase transformations. The first is the transformation of the original magnetite mineral into martite by oxidation resulting in trellis texture;the second is a simultaneous transformation by hydration into goethite and dehydration into martite. The samples typically show LREE depleted patterns relative to HREE, a characteristic similar to that of modern seawater. Also the strong positive Eu anomalies from the samples indicate the involvement of hydrothermal plumes of volcanic origin such as at mid ocean ridges (MOR). Yttrium (Y) has a strong positive anomaly pointing to the transportation of REEs as aqueous complexes within these ancient seas. The BIF samples have no positive Ce anomalies, suggesting that the oceans at that time were more reducing with no Ce fractionation than in present day oceans. The martite-goethite mineralization rather shows a positive Ce anomaly that derived from the enrichment in REE during the weathering of REE-bearing minerals. These results are integrated into existing literature on REE in BIFs worldwide and provide new insights into these heretofore unstudied BIFs of the northern edge of the Congo Craton.
基金financially supported by the Ministry of Higher Education, Cameroon, through the Special Allocation for the Modernization of Research (SAMR) granted to the first author
文摘Three monogenetic cones in the Baossi–Warack area, Ngaoundéré, Adamawa Plateau forming part of the Cameroon Volcanic Line(CVL) are documented in this study. Basaltic lavas(<1 km^3) scattered around these vents and restricted volcaniclastic deposits were emplaced by Hawaiian and mild strombolian style eruptions. The lavas are porphyritic, mainly composed of olivine(chrysolite) and clinopyroxene(diopside and augite) phenocrysts and plagioclase(andesine) microphenocrysts. Accessory minerals include titano-magnetite and titano-hematite, nepheline,apatite and amphibole xenocrysts. Sanidine occurs in some samples and sodi-potassic albite in others. Some olivines and clinopyroxenes exhibit resorbed margins and thin reaction rims while plagioclase displays oscillatory zoning, and sieved textures as a result of magma mixing. Whole-rock geochemistry data indicates that the lavas are silica-undersaturated, composed of basanites and basalts, showing little compositional variations(SiO_2: 39.20 wt.%–48.01 wt.%,MgO: 5.29 wt.%–9.70 wt.%). Trace elements patterns of these lavas suggest they are enriched in LILE including Pb,probably due to crustal contamination. REE patterns suggest cogenetic magmas below Baossi 1 and Baossi 2 volcanoes,and distinct sources below Warack volcano and nearby lavas.The lavas studied show affinity to high-μ(HIMU), enriched type Ⅰ(EM1) and Oceanic Island Basalt(OIB)-like mantle signatures and thus indicate a heterogeneous mantle source underneath the vents as noted at other monogenetic and polygenetic volcanoes along the CVL. Primary melts derived from low degrees of partial melting(0.5%–2%) and encountered low rates of fractionation, and crustal contamination coupled with magma mixing. These melts evolved independently through structural weaknesses in the basement.
文摘Exploration for primary gold in tropical settings is often problematic because of deep weathering and the development of a thick soil cover. In this paper we present the results of both chargeability and resistivity surveys carried out over the Belikombone hill gold prospect (14?00' - 14?25'E, 5?25' - 6?00'N) in the Betare Oya area (eastern Cameroon), where previous soil sampling had identified gold anomalies. The geophysical data were obtained using Syscal Junior 48 resistivity meter and the Schlumberger configuration array for both the vertical electrical soundings (VES) and horizontal profiling. These data were further built into a GIS framework and the continuity of favourable gold-bearing structures at depth modeled using WINSEV, RED2INV and SURFER extensions softwares. IP (Induced Polarization)-chargeability and resistivity data combined, have identified irregular anomalous zones trending NE-SW. This trend is consistent with the attitude of most auriferous quartz veins exposed in artisanal pits and parallel to the regional shear zone system and foliations. The high resistivity anomalies correspond to quartz veins while the relatively high IP anomalies correspond to low sulphide ± gold concentrations in the quartz veins. Modeling IP-chargeability and resistivity data prepared as contours and 3D maps, culminated to the development of an inferred, irregular and discontinuous mineralized body at depths of up to 95 m. The size and shape of this mineralized body can only later be tested by drilling to ascertain the resource.
基金supported by CAS-TWAS under grant FR 3240267248the National Natural Science Foundation of China(41021003)the Research Project of State Key Laboratory of Geodesy and Earth's Dynamics(SKLGED2013-4-1-Z)
文摘We used the Earth Gravitational Model （EGM2008） data sets to analyze the regional gravity anoma- lies and to study the underground structures in Cameroon. We first created a high-resolution Free-Air anomaly database, then corrected the gravity field of the topographic effect by using ETOPO1 DEM with a resolution of 0.01~ to obtain the Bouguer anomaly, then applied a multi-scale wavelet-analysis technique to separate the gravity-field components into different parts of shallow-to-deep origins, and finally used the logarithmic power spectrum technique to obtain detailed images and corresponding source depths as well as certain lateral inho- mogeneity of structure density. The anomalies of shallow origin show successive elongated gravity ＂highs＂ and ＂lows＂ attributable to subsurface Tertiary and lower Cretaceous undulations. Our results are in good agreement with previous investigations.
基金financially supported by the Ministère des Affaires Economiques (Project SGB/ NAT 91-98)
文摘Bioko Island（3008 m a.s.l） is located in the presently more active volcanic zone of the Cameroon Line and composed essentially of alkaline basalts and hawaiites, and lesser mugearites. The rocks show microlitic porphyritic texture with phenocrysts of olivine（83% 〈 Fo 〈 87%） and clinopyroxene in a matrix of plagioclase, clinopyroxene and oxides. Hawaiites and mugearites also include phenocrysts of plagioclase（An62-67Ab35-32Or3-1）. Major element variation diagrams show an increase in Si O2, Al2O3, Na2 O and K2 O with increasing Mg O for the studied rock groups. The rocks are characterized by low（^86Sr/^87Sr）i ratios（0.70320e0.70406）, high 3Nd（t） values（2.56e4.33） and high（^206Pb/^204Pb）i ratios（20.032e20.035） values.Basalts are enriched in LILE and LREE, and have（Hf/Sm）N= 0.57e1.16. These geochemical signatures are similar to those of the Mount Cameroon rocks, and might be attributed to low degrees of partial melting from a garnet-amphibole-bearing mantle source. The trace elements and isotopic compositions suggest that the parental magma source might have involved HIMU- and EM1-components.
文摘Geophysical and geotechnical surveys were conducted in the Western Cameroon (Kekem area) following a landslide on argillaceous material in order to understand the triggering processes and mechanisms of this landslide and to assess the stability of the slope. The geophysical soundings consisting of vertical electrical soundings with the Schlumberger electrode array configuration were carried out to monitor the behaviour of electrical resistivity in the landslide. Geoelectrical data showed a zone of low resistivity values identified as a clayey sand-filled aquifer. This aquifer played an important role in the triggering process of the landslide. Geotechnical soundings showed that the aquifer had a thickness of 7.0 m. The depth from the landslide crest level to the failure surface reached 3.0 m and 20.6 m. Laboratory tests were then carried out in order to evaluate the cohesion of the soil and the angle of internal friction, and to calculate the safety factor in view of making a stability analysis. The laboratory results exhibited a soil with low consistency, almost doughy. The mean value of the safety factor (1.4) been lower than the slope stability coefficient (1.5), revealed that the slope is unstable, likely to know at any moment a reactivation of the slide. This study showed that electrical soundings coupled with geotechnical surveys are useful tools for the characterization of landslides.
文摘Mapping and documentation of lithological varieties and their corresponding geochemistry at the Kitongo uranium mineralization were concerned. The Kitongo U occurrence is hosted by granitic rocks that include interleaved sequences of metasedimentary and metavolcanic rocks of the collectively termed Poli Group. U-mineralization and Na-metasomatism are related and structurally controlled. The most promising uraniferous bodies are intimately related to intersections between the ductile ENE-trending faults and the brittle conjugate R' faults postdating the shearing event. The con- centration of uranium at fault intersections rather than along individual faults suggests that these zones that are dilatational in nature were also highly permeable and therefore the hydrothermal fluids ponded there could readily precipitate U therein. A two-stage albitization has altered the foliated granitic host rock and the second albitization that has over-printed the first one is more effective at fault intersections. Whole rock geochemistry was performed by using ICP-MS and ICP-AES respectively for major oxides, trace and REE. The U-bearing rock suite exhibits restricted range in SiO2 concentration (62.89% - 70.91%) and Al2O3 (13.16% - 18.59%) and it is poor in MgO (0.02% - 1.03%), CaO (0.24% - 1.88%) and K2O (0.08% - 5.32%). The mineralized rocks are however comparatively richer in Na2O (4.33% - 10.92%) compared to their barren counterparts. The host granite and associated granodioritic rocks in the area are weakly metaluminous, peralkaline, and are calc-alkaline. They are moderately to strongly fractionated and have tholeiitic and shoshonitic affinities with moderate to high HFSE (high field strength elements) and LILE (large ion lithophile elements) enrichment. The Rb/Sr, Rb/Ba and Sr/Ba ratios are 0.31, 0.14 and 1.48, respectively. U content in the mineralized granite is up to 651 ppm while the non-mineralized rock has only 2.4 ppm U. The REE patterns of the granite show LREE enrichment and strong Eu negative anomalies (Eu/Eu* = 0.03 to 0.48). The main mineralization stage characterized by local U, Na, Pb, Zn, Ga, Hf, Sr, Fe, Al, P and Zr enrichments is related to the second albitization event and could probably be associated in time with the calcite-uranium stage. The identification of fault segments favorable for uranium mineralization in northern Cameroon (Poli area) is important for understanding the genesis of hydrothermal ore deposits within continental strike-slip faults and therefore has great implications for exploration strategies.
文摘In Douala, economic capital of Cameroon, annual rainfall and temperature from its meteorological station (latitude: 4o00'N;longitude: 9o43'E;elevation: 5.0 m) were obtained and analysed to investigate the impact of climate variability on groundwater recharge. The climate shows a strong evidence of changes towards persistent weather conditions. The region is mainly characterized by a mean inter-annual temperature of 27.4oC and influenced by the mount Cameroon (4095 m in elevation). A recent decrease in mean annual rainfall occurred since 1982. The average annual rainfall which was 4200 mm with about 220 days of rainfall from 1917 to 1937 has moved to 4049 mm for the period 1937-1957, to 3826 mm for the period 1968-1988 and to 3619 mm for the period 1971-2001. Between, 1997 and 2007, the total number of days of rainfall has not exceeded 220 (193 days of rainfall in 1998 and 216 days of rainfall in 1999). By using Gauss law on 31 years (1971-2001) of annual rainfall, one note that the value 2850 mm has 20% of luck to be not observed and the value 4219 mm has 20% of luck to be exceeded. Douala already suffers from water shortage not because of decrease of rainfall but due to quality of underground water and salty taste of the main river catched for water supply. Moreover, precipitation is considered as the main replenishment source of all water resources in the study area (watershed of Besseke). The calculated interannual groundwater recharge rate (potential recharge, not necessarily real) is about 9% compared to the interannual total precipitation received by this area located closer the Atlantic Ocean (Gulf of Guinea). Groundwater discharge from the aquifer occurs between November and March.
文摘Up to date, tropical mountainous ecosystems still lack in depth information on soil and environmental characteristics which are major factors limiting optimum crop production. The objective of this work was to study soil characteristics and to evaluate the land capability level for the production of some common tropical crops in mountainous ecosystem soils of North West Cameroon. Soil sampling was done following a randomized complete block design (RCBD) with four replications for three topographic positions (upslope, midslope and footslope) and at two depths (0 - 20 cm and 20 - 100 cm). It was completed by standard laboratory analyses. The fertility capability classification (FCC) system enabled to identify soil limitations and to classify soils into FCC units. Land and climate were evaluated by simple limitation and parametric methods. Globally, the soils were dark-colored, sandy clayey to clayey, compact and very acidic (pHH2O = 4.3 - 5.8). The organic matter (3.7% - 5.1% dry matter), total nitrogen (0.08% - 0.56%) and available phosphorus (22.1 to 30.9 mg?kg?1) recorded for the 0 - 20 cm depth then reduced with depth but midslope values were also lower. The C/N ratio varied between 9 and 45. Low C/N values appeared mostly in 0 - 20 cm depth at the upslope and downslope soils and subsurface soils of midslope position. Exchangeable Ca was very low to low (1.43 - 3.6 cmol + kg?1), Mg was very low to low (0.39 - 1.5 cmol + kg?1), K was low to medium (0.2 - 0.54 cmol + kg?1) and Na was very low (?1). The sum of exchangeable bases was very low (3.02 - 5.19 cmol + kg?1), cation exchange capacity was low to moderate (8.60 - 25.6 cmol + kg?1) and base saturation was very low to low (19.27% - 36.97%). Leaching of bases under heavy rainfall is a major cause of soil acidification under humid topical ecosystems. The Ca/Mg/K ratio was unbalanced and Mg was the most relatively concentrated base in all the soils. There was a clear variation of most of the soil properties along the slope and with depth. The soils were classified in the FCC system as aek for the upslope soils, Caek for the midslope soils and Cagk for the footslope soils. The principal limitations to production of huckleberry, beans, maize and potatoes were heavy rainfall, wetness, steep slope, soil texture/structure and low soil fertility. These constraints might be overcome by farming at the end of the raining season, contour ploughing, terracing, fertilization and liming.
文摘Stream sediment geochemistry remains a versatile tool in exploration especially in regions where knowledge of the primary mineralization is lacking and the exploration activities are still at reconnaissance stage. In this study, we investigate the concentrations of gold and associated elements in stream sediment samples from the Vaimba-Lidi drainage system in northern Cameroon;a relatively remote area where alluvial gold is worked locally, and exploration activities are at early stage. The main river and its principal first and second order tributaries were sampled, panned for gold grain recovery and the 100 μm size fraction analyzed for Au by fire assay with Ni finish. A suite of other elements were analyzed for by inductively coupled plasma mass spectrometry (ICP-MS). Gold grades estimated by the panning and weighing technique rarely exceed1 g/t while the Au concentrations from chemical analysis range from 3.0 to 354.0 ppm. The spatial distribution of gold and all the other elements are presented as point symbol maps and the data analyzed using multivariate statistics. From the principal component analysis (PCA), the As-Mo-W-Ag as well as the Au-Zn factors point to the presence of primary hydrothermal gold-sulphide mineralization in the area and this can be further investigated. These results highlight the importance of multielement analysis and multivariate statistical interpretation of sediment geochemical data in inferring the nature of the underlying primary mineralization in any region.
文摘In Cameroon, despite extensive control efforts against HIV/AIDS, the number of new HIV infections is still on the rise. The factors contributing to this are not clearly understood. We hypothesized that it may lie on people living with HIV (PLHIV). In a case-control descriptive study, we studied the characteristics and sexual risky behaviour of PLHIV in the North West Region of Cameroon which has the highest HIV prevalence. Participants were screened for HIV and a structured questionnaire was used in data collection. An equivalent number (350) of PLHIV and controls who did not differ with respect to age and sex participated. Relative to the control, PLHIV were generally less educated (P < 0.001), poorer and less privileged (P < 0.001) with no stable source of income. Among participants that were once married, a greater proportion of PLHIV were divorced (OR = 5.23, P = 0.007), and widows (OR = 2.73, P = 0.001). Among participants that were single, a relatively greater proportion of PLHIV practiced multi-partner sex (OR = 4.55, P< 0.001). History of STDs was higher in PLHIV than the control (OR = 1.88, P = 0.001). Out of 350 PLHIV, 280 (80%) admitted to having had sexual intercourse after being diagnosed of which only 127 (41.78%) admitted to using condoms and 132 (47.14%) admitted to concealing their HIV status from their sexual partner(s). These findings have implications in HIV control programs which should target the poor and the less educated, as well as the sexual behaviour of PLHIV, so as to reverse the current rising trend of new infections in the country.
文摘Iron ore deposits hosted by Precambrian banded iron formation(BIF)are the most important source of mineable iron.In Cameroon,they are located in the southern part of the country.This study reports the petrological and geochemical data of iron ores collected from a weathering profile in the Mamelles BIF deposit,SW Cameroon.The profile is composed of three levels which are from the bottom to the top:the saprock,the ferruginous horizon,and the loose horizon.Eight representative iron ore samples(rock fragments and loose clayey material)were collected along the profile and were subjected to petrographic and geochemical analyses.Their mineralogy consists of martite,goethite,quartz,and lesser amounts of hematite,magnetite,kaolinite,and halloysite.The presence of minerals such as kaolinite and goethite in the Mamelles iron ores suggests their supergene origin.Geochemically,the saprock is characterized by high iron content(70.25 wt%Fe_(2)O_(3) t),and low silica(26.38 wt%SiO_(2))and alumina(1.14 wt%Al_(2) O_(3)).The rock fragments collected from the ferruginous horizon display higher Fe2 O3 t(72-76.40 wt%),Al_(2) O_(3)(2.80-5.43 wt%),and lower SiO_(2)(16.70-18.35 wt%)contents,suggesting the leaching of silica during the enrichment process.The loose clayey samples collected from both the ferruginous horizon and the upper loose horizon show lower iron and higher silica contents.When normalized to the underlying BIF saprock,both rock fragments and loose clayey ores display LREE enrichment,suggesting that they formed through supergene processes.Economically,most of the Mamelles iron ores are classified as medium-grade ores and a few display acceptable contents in contaminants.Overall,this petrological and geochemical study of the Mamelles iron ores revealed encouraging results.Given its strategic location near the deep seaport,the deposit should be investigated in more detail for its mining potential.
基金financially supported by FORAFAMA and COBAM project
文摘Forest logging in the Congo Basin has led to forest fragmentation due to logging infrastructures and felling gaps. In the same vein, forest concessions in the Congo Basin have increasing interest in the REDD＋ mechanism. However, there is little information or field data on carbon emissions from forest degradation caused by logging. To help fill this gap, Landsat 7 and 8 and SPOT 4 images of the East Region of Cameroon were processed and combined with field measurements （measurement of forest roads widths, felling gaps and log yards） to assess all disturbed areas. Also, measurements of different types of forest infrastructures helped to highlight emission factors. Forest contributes to 5.18 % of the degradation of the annual allowable cut （AAC） （84.53 ha） corresponding to 4.09 % of forest carbon stock （6.92 t ha^-1）. Felling gaps constitute the primary source of degradation, represented an estimated area of 32.41 ha （2 % of the cutting area） far ahead of primary roads （18.44ha） and skid trails （16.36 ha）. Assessment of the impact of degradation under the canopy requires the use of high resolution satellite images and field surveys.
文摘AIM:Gallstone disease is increasing in sub-saharan Africa (SSA).In the west, the majority of stones can be dissolved with bile salts,since the major component is cholesterol.This medical therapy is expensive and not readily accessible to poor populations of SSA.It was therefore necessary to analyze the chemical composition of biliary stones in a group of patients,so as to make the case for introducing bile salt therapy in SSA.METHODS: All patients with symptomatic gallstones were recruited in the study. All stones removed during cholecystectomy were sent to Houston for x-ray diffraction analysis.Data on age, sex, serum cholesterol,and thepercentage by weight of cholesterol, calcium carbonate, and amorphous material in each stone was entered into a preestablished proforma. Frequencies of the major components of the stones were determined.RESULTS:Sixteen women and ten men aged between 27 and 73 (mean 44.9) years provided stones for the study.The majority of patients (65.38%) had stones with less than 25% of cholesterol.Amorphous material made up more than 50% and 100% of stones from 16 (61.53%) and 9 (34.61%) patients respectively.CONCLUSION:Cholesterol is present in small amounts in a minority of gallstones in Yaounde. Dissolution of gallstones with bile salts is unlikely to be successful.
