Old timber plantations and secondary forests attain levels of plant diversity and structure similar to primary forests in the West African humid tropics

Considering the high rate of primary forest degradation and loss in the tropics, the ability to conserve plant diversity within alternative forest landscape components is critical to biodiversity conservation. This study compares the restoration potential of old forest plantations and secondary forests. We assessed and compared the floristics, plant species diversity, conservation value, and structure of old (42-47 years) timber plantations of Aucoumea klaineana Pierre, Cedrela odorata L., Tarrietia utilis Sprague, and Terminalia ivorensis A. Chev. and similar-aged secondary forests with nearby primary (old-growth) forests in the moist and wet forest zones of Ghana. We established a systematic sampling set-up of ninety-three 20 m x 20 m plots in total on 11 sites, with smaller nested subplots for saplings and ground vegetation. The floristic composition of the plantation and secondary forest stands were similar to that of the primary forests, with many rare and restricted-range species shared by the three forest types. Approximately 77% and 60% of primary forest plant species also occurred in plantation and secondary forests, respectively. Species diversity, measured by the Shannon-Wiener Diversity Index (H') and Simpson Index (S), for the primary forest (H'=3.07, S = 0.91) was not statistically different from the plantation (H'=2.85, S = 0.87) or secondary (H'=2.95, S = 0.88) forests. Overall, species richness was higher in the primary and secondary forests compared to the plantations. At the tree stratum (>= 10 cm DBH), the assessed diversity indices were significantly different between the primary forest and the plantations. However, such differences did not exist among the saplings (10 cm > DBH >= 2 cm) and ground vegetation (< 2cm DBH). The plantations and secondary forests were similar to the primary forests for all the structural characteristics assessed. However, basal area and bole volume were significantly higher in the plantations compared with secondary forests. Conservation value (using Genetic Heat Index as an indicator) was highest in one of the C. odorata plantations (W-CO). Our study demonstrates that plantation and secondary forests can develop into structurally complex and floristically diverse self-organized stands similar to primary forests. Passive conversion of plantations to more natural ecosystems is an effective and low-cost forest restoration strategy leading to diverse ecosystems with high conservation value.Peer reviewe

Structural Characteristics of Reinforced Palm Kernel Shell Concrete Deep Beams

This paper evaluates the structural characteristics of deep beams made from reinforced palm kernel shell concrete (PKSC) and normal weight concrete (NWC). Twelve PKSC and NWC deep beam samples, with and without shear reinforcement were tested under three-point loading and their structural behavior studied. The ultimate shear strength of PKSC beams increased with a decrease in the shear span-to- depth ratio. Post diagonal cracking shear resistance is greater in PKSC deep beams than beams of normal weight concrete. The shear capacity of the PKSC and NWC deep beams were assessed to be un-conservative using ACI 318-99, ACI 318-05, Eurocode (EC) 2 and a kinematic model, when compared with the experimental results. Nonetheless, this necessitated the development of a calibration procedure to correct the bias inherent in these models. Calibrated shear strength models revealed the compressive strength and the ratio of the shear span-to-total depth as significant influential parameters for correcting the inherent bias in the original deterministic shear strength models. The calibrated functional model of ACI-318-99 may produce conservative predictions, given this limited number of test specimens. Therefore future studies should investigate the reliability of the calibrated models, and quantifying the uncertainties in the estimated coefficients of parameters, using a much larger representative dataset

Above-ground carbon stocks and timber value of old timber plantations, secondary and primary forests in southern Ghana

High deforestation rates, especially in the tropics, currently result in the annual emission of large amounts of carbon, contributing to global climate change. There is therefore an urgent need to take actions to mitigate climate change both by slowing down deforestation and by initiating new sinks. Tropical forest plantations are generally thought to sequester carbon rapidly during the initial years but there is limited knowledge on their long-term potential. In this study, we assessed the carbon sequestration in old (42-47 years) timber plantations of Aucoumea klaineana, Cedrela odorata, Tarrietia utilis, and Terminalia ivorensis, and secondary forests of similar ages, by comparing their basal areas and above-ground carbon stocks (AGC) to that of nearby primary forests. Additionally, we estimated and compared timber volume and stumpage value in the three forest types. Systematic random sampling of ninety-three 20 m x 20 m plots in eleven forest sites (2 secondary forests, 2 primary forests, and 7 timber plantations) was undertaken to determine the effect of forest type on AGC, basal area, timber volume, and stumpage value. After 42 years of growth, mean AGC of the timber plantations (159.7 +/- 14.3 Mg ha(-1)) was similar to that of primary forests (173.0 +/- 25.1 Mg ha(-1)) and both were significantly higher than the mean AGC of the secondary forests (103.6 +/- 12.3 Mg ha(-1)). Mean basal area and timber volume of the timber plantations and secondary forests were similar to that of the primary forests, though in each case the timber plantations had significantly higher values compared to the secondary forests. Mean timber value of the plantations ($8577 ha(-1)) was significantly higher than both secondary ($1870 ha(-1)) and primary forests ($3112 ha(-1)). Contrary to our expectations, naturally regenerated trees (woody recruits) within the timber plantations had similar AGC levels, basal area, timber volume, and value compared to the secondary forests. Long-rotation tropical forest plantations under low-intensity management could achieve higher AGC levels and thus have higher climate change mitigation potential and timber values compared to naturally regenerated secondary forests, and are able to reach values similar to primary forests. Monoculture timber plantations could facilitate the successful colonization of their understoreys by native woody recruits that contribute considerably to stand AGC and timber values. Long-rotation forest plantations in the tropics therefore have a critical role to play in forest rehabilitation and climate change mitigation while having the potential to provide modest financial returns to landowners through selective harvesting of timber and/or payments for carbon sequestration.Peer reviewe

Comparison of post-fire planted and natural dry semi-deciduous forest communities in Ghana

Peer reviewe

The changing epidemiology of esophageal cancer in sub-Saharan Africa – the case of Ghana

Introduction: Esophageal cancer portends a grim prognosis. Most patients present with incurable disease. Scanty epidemiologic data on the disease has contributed to its low priority on the national. We sought to evaluate the current national trend in the presentation and outcome of esophageal cancer using our institutional experience from 1992 – 2010. Methods: This is a retrospective study based on 152 patients who were seen in our institution during the study period. The perioperative data of these patients were retrieved and the relevant details recorded. Histopathological reports were available for 75 patients managed over the period. The study setting was The National Cardiothoracic Centre, which serves as the only tertiary referral centre in the country for cardiothoracic problems. Results: There were 122 males and 30 females with a mean age of 57.8±11.7 years. The yearly trend from 1992 to 2010 showed a steady increase in the incidence of esophageal cancer. High alcohol consumption and smoking dominated the history of 82.2% of the patients. Squamous cell carcinoma accounted for 78.7% and adenocarcinoma 21.3%. Distribution of esophageal carcinoma by anatomical location was 84.9% for distal third, 11.8% for middle third and 3.3% for upper third. All patients presented with incurable disease. Conclusion: The study shows an increasing incidence of esophageal carcinoma in this country. Alcohol abuse and smoking are major risk factors; squamous cell carcinoma is the dominant histological type in this study.Pan African Medical Journal 2012; 13:

Value Co-creation Inside the Ridesharing Economy: Evidence from the Chinese Sharing Economy Experiencescape with Set-theoretic and SEM Applications

The study empirically examines value co-creative behaviors within the framework of ridesharing, complexity theory, and fsQCA. A total of 301, questionnaires were acquired through social media and conventional sources in the study. The questionnaires were analysed to validate our proposed hypotheses by using structural equation modelling (SEM) and fuzzy set qualitative comparative analysis (fsQCA), ostensibly to assess the direct (indirect) relationships, and all feasible solutions that defined Equifinality respectively. The SEM results of the study revealed that resources and experiential consumption remain the corner stone of distinct value formation; and the antecedents of commuters’ high intention to participate in ridesharing value co-creation. Furthermore, among the dimensions of experiential consumption, escapism was found to be the most influential contributor of commuters’ high intention to participate in ridesharing value co-creation. In terms of fsQCA, the results revealed seven (7) recipes of configurations (solutions) for predicting commuters’ high intention to participate in ridesharing value co-creation. Arguably, there is a chasm in literature with respect to ridesharing value co-creation. Whiles the study intends to address this chasm, the implications of the study will enhance managerial decision-making on how to combine their scarce resources to design memorable and authentic-laden services that will attract the commuting public for value co-creation. The study narrows the chasm and further deepens the stream of literature on sharing economy through its theoretical provision, and unique focus on value co-creation in the ambit of ridesharing. Keywords: Value co-creation/destruction, fsQCA, sharing economy, experience economy, memorable experience. S-D logic, complexity theory

The Explication Defence of Arguments from Reference

In a number of influential papers, Machery, Mallon, Nichols and Stich have presented a powerful critique of so-called arguments from reference, arguments that assume that a particular theory of reference is correct in order to establish a substantive conclusion. The critique is that, due to cross-cultural variation in semantic intuitions supposedly undermining the standard methodology for theorising about reference, the assumption that a theory of reference is correct is unjustified. I argue that the many extant responses to Machery et al.’s critique do little for the proponent of an argument from reference, as they do not show how to justify the problematic assumption. I then argue that it can in principle be justified by an appeal to Carnapian explication. I show how to apply the explication defence to arguments from reference given by Andreasen (for the biological reality of race) and by Churchland (against the existence of beliefs and desires)

High prevalence of multidrug-resistant tuberculosis among patients with rifampicin resistance using GeneXpert Mycobacterium tuberculosis/rifampicin in Ghana

AbstractObjective/BackgroundDrug-resistant strains of tuberculosis (TB) represent a major threat to global TB control. In low- and middle-income countries, resource constraints make it difficult to identify and monitor cases of resistance using drug susceptibility testing and culture. Molecular assays such as the GeneXpert Mycobacterium tuberculosis/rifampicin may prove to be a cost-effective solution to this problem in these settings. The objective of this study is to evaluate the use of GeneXpert in the diagnosis of pulmonary TB since it was introduced into two tertiary hospitals in Ghana in 2013.MethodsA 2-year retrospective audit of clinical cases involving patients who presented with clinically suspected TB or documented TB not improving on standard therapy and had samples sent for GeneXpert testing.ResultsGeneXpert identified 169 cases of TB, including 17 cases of rifampicin-resistant TB. Of the seven cases with final culture and drug susceptibility testing results, six demonstrated further drug resistance and five of these were multidrug-resistant TB.ConclusionThese findings call for a scale-up of TB control in Ghana and provide evidence that the expansion of GeneXpert may be an optimal means to improve case finding and guide treatment of drug-resistant TB in this setting

An outbreak of pneumococcal meningitis among older children (≥5 years) and adults after the implementation of an infant vaccination programme with the 13-valent pneumococcal conjugate vaccine in Ghana.

BACKGROUND: An outbreak of pneumococcal meningitis among non-infant children and adults occurred in the Brong-Ahafo region of Ghana between December 2015 and April 2016 despite the recent nationwide implementation of a vaccination programme for infants with the 13-valent pneumococcal conjugate vaccine (PCV13). METHODS: Cerebrospinal fluid (CSF) specimens were collected from patients with suspected meningitis in the Brong-Ahafo region. CSF specimens were subjected to Gram staining, culture and rapid antigen testing. Quantitative PCR was performed to identify pneumococcus, meningococcus and Haemophilus influenzae. Latex agglutination and molecular serotyping were performed on samples. Antibiogram and whole genome sequencing were performed on pneumococcal isolates. RESULTS: Eight hundred eighty six patients were reported with suspected meningitis in the Brong-Ahafo region during the period of the outbreak. In the epicenter district, the prevalence was as high as 363 suspected cases per 100,000 people. Over 95 % of suspected cases occurred in non-infant children and adults, with a median age of 20 years. Bacterial meningitis was confirmed in just under a quarter of CSF specimens tested. Pneumococcus, meningococcus and Group B Streptococcus accounted for 77 %, 22 % and 1 % of confirmed cases respectively. The vast majority of serotyped pneumococci (80 %) belonged to serotype 1. Most of the pneumococcal isolates tested were susceptible to a broad range of antibiotics, with the exception of two pneumococcal serotype 1 strains that were resistant to both penicillin and trimethoprim-sulfamethoxazole. All sequenced pneumococcal serotype 1 strains belong to Sequence Type (ST) 303 in the hypervirulent ST217 clonal complex. CONCLUSION: The occurrence of a pneumococcal serotype 1 meningitis outbreak three years after the introduction of PCV13 is alarming and calls for strengthening of meningitis surveillance and a re-evaluation of the current vaccination programme in high risk countries

Accuracy of point-of-care testing for circulatory cathodic antigen in the detection of schistosome infection : Systematic review and meta-analysis

Objective To assess the accuracy of point-of-care testing for circulatory cathodic antigen in the diagnosis of schistosome infection. Methods We searched MEDLINE, EMBASE, LILACS and other bibliographic databases for studies published until 30 September 2015 that described circulatory cathodic antigen testing compared against one to three Kato–Katz tests per subject – for Schistosoma mansoni – or the filtration of one 10-ml urine sample per subject – for S. haematobium. We extracted the numbers of true positives, false positives, true negatives and false negatives for the antigen testing and performed meta-analyses using a bivariate hierarchical regression model. Findings Twenty-six studies published between 1994 and 2014 met the inclusion criteria. In the detection of S. mansoni, a single antigen test gave a pooled sensitivity of 0.90 (95% confidence interval, CI: 0.84–0.94) and a pooled specificity of 0.56 (95% CI: 0.39–0.71; n = 7) when compared against a single Kato–Katz test. The corresponding values from comparisons with two to three Kato–Katz tests per subject were 0.85 (95% CI: 0.80–0.88) and 0.66 (95% CI: 0.53–0.76; n = 14), respectively. There appeared to be no advantage in using three antigen tests per subject instead of one. When compared against the results of urine filtration, antigen testing for S. haematobium showed poor sensitivity and poor specificity. The performance of antigen testing was better in areas of high endemicity than in settings with low endemicity. Conclusion Antigen testing may represent an effective tool for monitoring programmes for the control of S. mansoni