Mapping Artisanal and Small-Scale Gold Mining in Senegal Using Sentinel 2 Data.

Artisanal and small-scale gold mining (ASGM) represents a significant economic activity for communities in developing countries. In southeastern Senegal, this activity has increased in recent years and has become the main source of income for the local population. However, it is also associated with negative environmental, social, and health impacts. Considering the recent development of ASGM in Senegal and the difficulties of the government in monitoring and regulating this activity, this article proposes a method for detecting and mapping ASGM sites in Senegal using Sentinel 2 data and the Google Earth Engine. Two artisanal mining sites in Senegal are selected to test this approach. Detection and mapping are achieved following a processing pipeline. Principal component analysis (PCA) is applied to determine the optimal period of the year for mapping. Separability and threshold (SEaTH) is used to determine the optimal bands or spectral indices to discriminate ASGM from other land use. Finally, automatic classification and mapping of the scenes are achieved with support vector machine (SVM) classifier. The results are then validated based on field observations. The PCA and examination of spectral signatures as a function of time indicate that the best period for discriminate ASGM sites against other types of land use is the end of dry season, when vegetation is minimal. The classification results are presented as a map with different categories of land use. This method could be applied to future Sentinel scenes to monitor the evolution of mining sites and may also be extrapolated to other relevant areas in the Sahel.

Effect of two isolated vocal facilitating techniques glottal fry and yawn-sigh on the phonation of female speech-language pathology students: A pilot study.

OBJECTIVE: The purpose of this study was to determine the effect of two isolated vocal facilitating techniques, glottal fry and yawn-sigh, on the phonation of vocally healthy female speech-language pathology (SLP) students. STUDY DESIGN: A multigroup pretest-posttest design was used. METHODS: A group of thirty-six healthy female SLP students with a mean age of 18.1 years were assigned into three groups: a glottal fry group (practicing the facilitating technique glottal fry across 18 weeks, n=12), a yawn-sigh group (practicing the facilitating technique yawn-sigh across 18 weeks, n=12) and a control group (receiving no facilitating techniques, n=12). To compare vocal measures before and after this training period, an identical objective voice assessment protocol (maximum performance task, acoustic analysis, voice range profile and Dysphonia Severity Index) was performed in the three groups. Groups were compared over time using linear mixed models. Within-group effects of time were determined using post hoc pairwise comparisons. RESULTS: Glottal fry resulted in a significant decrease in lowest and highest intensity. Yawn-sigh resulted in a significant increase in fundamental frequency, a significant decrease in shimmer and noise-to-harmonic ratio, and a significant increase in highest intensity. CONCLUSIONS: Yawn-sigh may have a positive effect on the phonation of female vocally healthy future SLPs, whereas results are less supportive for using glottal fry in training this population's voice.

Estimation of mercury background values in sediment and biota of the Bijagós archipelago, Guinea-Bissau.

This work evaluates the mercury (Hg) contamination status (sediments and biota) of the Bijagós archipelago, off the coast of Guinea-Bissau. Sediments exhibited very low concentrations (<1-12ngg(-1)), pointing to negligible sources of anthropogenic Hg in the region. Nevertheless, Hg is well correlated to the fine fraction, aluminium, and loss on ignition, indicating the effect of grain size and organic matter content on the presence of Hg in sediments. Mercury in the bivalves Tagelus adansoni and Senilia senilis did not vary considerably among sites, ranging within narrow intervals (0.09-0.12 and 0.12-0.14µgg(-1) (dry weight), respectively). Divergent substrate preferences/feeding tactics may justify slight differences between species. The value 11ngg(-1) is proposed as the sediment background concentration for this West-African coastal region, and concentrations within the interval 8-10ngg(-1) (wet weight) may be considered as reference range for S. senilis and T. adansoni in future monitoring studies.