This paper explored the antecedents and the role of local artisans in Spatial Planning (SP) activities in Ghana. The paper was based on the results of an inspection of 5896 already built houses at Mepe in the Volta Re...This paper explored the antecedents and the role of local artisans in Spatial Planning (SP) activities in Ghana. The paper was based on the results of an inspection of 5896 already built houses at Mepe in the Volta Region of Ghana. A mixed method research approach was used to gather the data through snowball non-probability sampling technique. It enabled the researchers to identify 100 local artisans. Survey questionnaires were used, which was followed by structured interviews with five (5) elders who lived in the town for over 65 years. The results showed that the early houses were built on community lands with mud and thatch clustered with narrow and unnamed alleys. Property owners heavily depended on local artisans for professional guidance, although some artisans were ill-trained and unaware of existing government SP regulations. The study was limited to artisans who practiced at the local community level. The findings showed that many local artisans were poorly trained, resulting in poor workmanship and non-compliance with local planning regulations. The paper recommends the integration of SP into the artisanal curricula at both local and national levels to improve their skills.展开更多
Artisanal gold mining,a labor-intensive and antiquated technique,is a growing industry and the source of income for rural communities all over the world.However,artisanal gold mining has potential negative and long-te...Artisanal gold mining,a labor-intensive and antiquated technique,is a growing industry and the source of income for rural communities all over the world.However,artisanal gold mining has potential negative and long-term effects on economy,environment,and society.This study collected soil samples from 16 sample points including a control point to examine the pollution degrees and spatial distribution of heavy metals,as well as ecological and health risks associated with heavy metal pollution in the Ijero-Ekiti mining site,Nigeria.Geographical Information System(GIS)and remote sensing technologies were used to identify regions with high concentrations of heavy metals and assess the environmental impact of gold mining activities.The results show that the mean heavy metal concentrations of 16 soil pointa are 8.94(±5.97)mg/kg for As,0.18(±0.54)mg/kg for Cd,0.11(±1.06)mg/kg for Co,14.32(±3.43)mg/kg for Cr,6.89(±0.64)mg/kg for Cu,48.92(±11.77)mg/kg for Fe,135.81(±30.75)mg/kg for Mn,5.92(±0.96)mg/kg for Ni,5.72(±1.66)mg/kg for Pb,and 13.94(±1.38)mg/kg for Zn.The study reveals that heavy metal concentration in soils follows the order of Mn>Fe>Cr>Zn>As>Cu>Ni>Pb>Co>Cd.An analysis of soil samples indicates that 3 principal components(PCs)account for 70.008%of the total variance and there are strong positive correlations between various pairs of heavy metals.The total potential ecological risk index(309.599)in the study area is high.Non-carcinogenic risk suggests that there may be long-term health impacts on people who work in the mining areas due to chronic exposure to the environment.Based on the study,the hazard index of carcinogenic health risks associated with heavy metals through ingestion is 520.00×10^(–4).Dermal contact from As and Cr also increases the risk of cancer,with the highest hazard index value of 18.40×10^(–4).The lowest exposure pathway,with the hazard index value of 0.68×10^(–4),indicates that the inhalation of heavy metals has a comparatively low risk of cancer.This study recommends the formulation of policies to monitor the Ijero-Ekiti mining site and other regions in Nigeria where indiscriminate artisanal gold mining activities exist.展开更多
Traditionally,food sustainability has been considered solely in the stage of agricultural production.However,globalization,the expansion of the food production industry,and the emergence of supermarket chains that con...Traditionally,food sustainability has been considered solely in the stage of agricultural production.However,globalization,the expansion of the food production industry,and the emergence of supermarket chains that control the retail food market require specific significant changes in supply chains in the food sector and,therefore,we need to address the economic,social,and environmental impacts of these events.On the other hand,social selling has increased rapidly in recent years,with a further boom,following current events related to the coronavirus disease(COVID-19).This explosion of social sales,where there are usually no control and regulation entities,can bring problems associated with mishandling items.In this paper,we expose how Blockchain technology supports the traceability of social sales by validating the data provided by the chain participants such as digital health passports,production and transport data in the sale process;the proposed solution generates recommendations on productmanagement considering the agreements previously made by the network actors.To evaluate the proposed smart contracts,we useHyperledger Caliper,obtaining an average throughput of 12.6 transactions per second and an average latency of 0.3 s for the asset update process.We also use a study case to evaluate the proposed project platform’s selling-transport stage using Internet of Things(IoT)sensors.展开更多
The majority of the population of Burkina Faso lives from agriculture and therefore depends on the land. The main objective of this study is to assess the quality of the soils in the area linked to artisanal mining ac...The majority of the population of Burkina Faso lives from agriculture and therefore depends on the land. The main objective of this study is to assess the quality of the soils in the area linked to artisanal mining activities. The methodology adopted consisted in sampling and characterizing the main types of soil. In order to assess the level of soil pollution by artisanal mining, parameters such as the geo-accumulation index (Igeo) and the contamination factor (CF) are calculated. A prediction of acid mine drainage (AMD) was also carried out on samples of mine tailings which are potential sources of pollution of these soils. The results obtained show that the soils in Yimiougou are of nil to low agronomic interest. The Igeo shows that for lead, copper, zinc and arsenic the levels found in the different morphological units are partly attributable to human action and specifically artisanal mining. The values of the contamination factor indicate contamination. Cobalt presents the lowest contamination. For cadmium, the different types of soil are moderately contaminated except for the FITLC type, which has a CF value of 0.50, therefore synonymous with low or absent contamination. The various morphological units studied are very heavily contaminated with zinc, copper, lead and arsenic. The pH and conductivity values indicate that the mine tailings samples are non-acidogenic, therefore not yet oxidized. As for the sulphide contents, they show that only samples S17, S22, S23 and S24 present values that are strictly above the threshold (0.3%) and therefore potentially acid-generating. The comparative study of the acid potential (AP) and the neutralization potential (NP) reveals that the neutralization potentials of the different samples are clearly higher than the acid potentials even for the samples which present a proven acidification potential (S17, S22, S23 and S24). These results show that the mine tailings have the natural capacity to neutralize any possible mine drainage, given the presence of acid-eating minerals such as the carbonates associated with the mineralization.展开更多
Maritime safety equipment allows to prevent and minimize the risks inherent to navigation at sea. However, in the artisanal maritime fishery in Gabon, fishermen are confronted with the major difficulty of the inaccess...Maritime safety equipment allows to prevent and minimize the risks inherent to navigation at sea. However, in the artisanal maritime fishery in Gabon, fishermen are confronted with the major difficulty of the inaccessibility of protective tools to carry out fishing trips in all peace of mind. The absence of equipment to help maritime navigation poses the problem of insecurity in which the various artisanal fishermen work, often victims of numerous accidents at sea. This article aims at highlighting the difficulties of accessibility, by the fishermen, of all the conventional protection tools recommended by the administrations. In fact, the methodology used is based on the consultation of official reports and publications on the subject, field observations and semi-structured interviews with 110 actors. The results obtained reveal, on the one hand, a plethora of conventional protective equipment required of fishing vessels. On the other hand, they reveal the high cost of safety equipment which creates, among the professionals concerned, a reluctance to acquire all of the said tools and forces the interested parties to associate them very often with the traditional procedures for rescue at sea.展开更多
Active restoration is a critical component of biodiversity conservation for degraded tropical forest ecosystems caused by artisanal gold mining, and the success of restoration is dependent on native species selection....Active restoration is a critical component of biodiversity conservation for degraded tropical forest ecosystems caused by artisanal gold mining, and the success of restoration is dependent on native species selection. However, significant knowledge gaps exist regarding when and where to plant trees. This article reports on a revegetation trial undertaken in St Elizabeth, Mahdia, Guyana, to assess the survival and RGR (Relative Growth Rate) of three native woody trees and shrubs planted within three years old Acacia mangium Willd trees pruned and unpruned blocks. ANOVA (Analysis of Variance) for a completely randomized block design with four blocks, two pruned and two unpruned, within A. mangium plots. Biochar treatment was added to the plants during transplanting. Thirty-six (36) wildlings of Humiria balsamifera (Aublet.) (Tauroniro), Goupia glabra Aublet (Kabukalli), and Vismia guianensis (Aublet.) Choisy (Bloodwood) were collected and raised in a tree nursery for two weeks. The native plants were transplanted 3 m apart, survival observations and each seedling’s initial height and diameter were measured and recorded. After the experiment, 13% of seedlings from a population of 720 had died, with the highest mortality being experienced at the 92 days of the experiment (t ≤ 122 days). While the overall survival rates were high, emphasizing the importance of field trials on native and exotic species in different environments is essential to fill the knowledge gaps on suitable species for restoration in degraded areas with other land use histories.展开更多
This paper investigates a unique and interesting archaeological case,namely the newly found inscription copied from Qianzi Wen(The Thousand Character Essay)on the south wall in the main chamber of Mogao cave 9,and ana...This paper investigates a unique and interesting archaeological case,namely the newly found inscription copied from Qianzi Wen(The Thousand Character Essay)on the south wall in the main chamber of Mogao cave 9,and analyzes a series of research topics related to the inscription,hoping to thoroughly reveal the historical and cultural phenomenon of the high popularity and extensive spread of Qianzi Wen in the Tang dynasty,and attempt to restore some living scenes of ancient school students and cave-making artisans.To the best of our knowledge,this is the first time to find Qianzi Wen on the wall in Mogao caves.展开更多
The Jiapigou gold mine area, located in the upper reaches of the Songhua River, was the first and largest artisanal gold mine once in China, and it used to be prominent in two marking years(1870 and 1974). Jiapigou ar...The Jiapigou gold mine area, located in the upper reaches of the Songhua River, was the first and largest artisanal gold mine once in China, and it used to be prominent in two marking years(1870 and 1974). Jiapigou area had a gold mining history of more than 190 years, which was first opened in 1820. Gold extraction with algamation was applied as the dominant method of excavation from 1940 to 2008, and a total of more than 100 t of gold were extracted from the mine using this method and it was estimated that 100–200 t Hg were released, thus causing severe mercury environmental pollution in the mining area. In the experimental campaigns of this study, in situ air and soil Hg concentrations and air-soil Hg fluxes were measured from April 2009 to December 2011. The results showed that in the study area the total gaseous mercury(TGM) concentration exhibited remarkable spatial and temporal distribution patterns, i.e. the TGM gradually decreased following the increase in distance to gold mining sites in space, and the values in spring, summer and autumn were elevated by 1–2 orders of magnitude in comparison with those in winter. Furthermore, at other sampling sites the total soil mercury(TSM) concentration in spring was higher than that in autumn, except for the contrary laws demonstrated at the Erdaogou mining site. However, in spring and winter the Hg flux between air and soil was under the control of different environmental factors, and the characteristics were clear and distinct. In spring the Hg flux between air and soil was directly under the control of solar irradiation, and the releasing process was predominant with a remarkable positive correlation to solar irradiation. Nevertheless, in winter the Hg fluxes were indirectly under the control of solar irradiation, which caused thermal inversion due to the thick snow cover. The depositing process was predominant and the correlations between Hg flux and air temperature was remarkably negative, and there was a positive correlation between Hg flux and solar irradiation.展开更多
AIM： To evaluate the effect of incision types for Artisan phakic intraocular lens （PIOL） implantation on ocular higher-order aberrations （HOAs）.METHODS： A retrospective review was conducted of the patients who h...AIM： To evaluate the effect of incision types for Artisan phakic intraocular lens （PIOL） implantation on ocular higher-order aberrations （HOAs）.METHODS： A retrospective review was conducted of the patients who had undergone Artisan PIOL implantation for the correction of myopia and followed up for at least 6mo. Patients are classified into 2 groups considering the incision type： cornea group with patients undergone clear corneal incision; sclera group with patients undergone sclera tunnel incision. All patients with postoperative astigmatism of under 1 diopter （D） were included to minimize the effect of residual astigmatism on postoperative HOAs. Visual acuity, special equivalents, astigmatism, predictability （±1 D from target refraction）, HOAs （coma, trefoil, spherical aberration）, and corneal endothelial counts were analyzed preoperatively and 6mo postoperatively.RESULTS： At the postoperative 6mo, all patients of both groups achieved uncorrected visual acuity of 16/20 or better, and significantly decreased the spherical equivalents compared with preoperative values. The predictability of refractive correction was 96% in the former, and 94% in the latter. Unlike the sclera group, preoperative astigmatism decreased significantly in cornea group at postoperative 6mo. The HOAs increased significantly at postoperative 6mo compared to the preoperative values in both groups, and the root mean square （RMS） total and trefoil wavefront aberration of cornea group were significantly higher than those of sclera group.CONCLUSION： Although corneal incision significantly reduces preexisting astigmatism, the postoperative 6mo of total RMS and trefoil aberration change may deteriorate the visual quality after Artisan PIOL implantation.展开更多
Artisanal gold mining in local communities is on the increase. This has led to concerns about mercury pollution resulting from these mining activities. This study was conducted to assess the level of mercury pollution...Artisanal gold mining in local communities is on the increase. This has led to concerns about mercury pollution resulting from these mining activities. This study was conducted to assess the level of mercury pollution in rivers and streams around artisanal gold mining areas of the Birim North District of Ghana. Rivers, streams, sediments and boreholes were sampled to determine total mercury levels during the wet and dry seasons and to explore the potential impact of the mercury levels on water quality in the area. The results show that the total mercury concentrations measured upstream were significantly lower than concentrations in samples taken downstream. Also, the total mercury concentrations measured in the stream water samples in both seasons exceeded the WHO guideline limit (1.0 μg/L) for drinking water. However, one downstream total mercury concentration exceeded the guideline limit in the dry season. The total mercury concentrations in sediments upstream and downstream in both seasons exceeded the US-EPA guideline value of 0.2 mg/kg. The boreholes in the study area have total mercury concentrations exceeding the WHO guideline limit during both seasons. Total mercury concentrations in the boreholes in the wet season were lower than the dry season.展开更多
文摘This paper explored the antecedents and the role of local artisans in Spatial Planning (SP) activities in Ghana. The paper was based on the results of an inspection of 5896 already built houses at Mepe in the Volta Region of Ghana. A mixed method research approach was used to gather the data through snowball non-probability sampling technique. It enabled the researchers to identify 100 local artisans. Survey questionnaires were used, which was followed by structured interviews with five (5) elders who lived in the town for over 65 years. The results showed that the early houses were built on community lands with mud and thatch clustered with narrow and unnamed alleys. Property owners heavily depended on local artisans for professional guidance, although some artisans were ill-trained and unaware of existing government SP regulations. The study was limited to artisans who practiced at the local community level. The findings showed that many local artisans were poorly trained, resulting in poor workmanship and non-compliance with local planning regulations. The paper recommends the integration of SP into the artisanal curricula at both local and national levels to improve their skills.
文摘Artisanal gold mining,a labor-intensive and antiquated technique,is a growing industry and the source of income for rural communities all over the world.However,artisanal gold mining has potential negative and long-term effects on economy,environment,and society.This study collected soil samples from 16 sample points including a control point to examine the pollution degrees and spatial distribution of heavy metals,as well as ecological and health risks associated with heavy metal pollution in the Ijero-Ekiti mining site,Nigeria.Geographical Information System(GIS)and remote sensing technologies were used to identify regions with high concentrations of heavy metals and assess the environmental impact of gold mining activities.The results show that the mean heavy metal concentrations of 16 soil pointa are 8.94(±5.97)mg/kg for As,0.18(±0.54)mg/kg for Cd,0.11(±1.06)mg/kg for Co,14.32(±3.43)mg/kg for Cr,6.89(±0.64)mg/kg for Cu,48.92(±11.77)mg/kg for Fe,135.81(±30.75)mg/kg for Mn,5.92(±0.96)mg/kg for Ni,5.72(±1.66)mg/kg for Pb,and 13.94(±1.38)mg/kg for Zn.The study reveals that heavy metal concentration in soils follows the order of Mn>Fe>Cr>Zn>As>Cu>Ni>Pb>Co>Cd.An analysis of soil samples indicates that 3 principal components(PCs)account for 70.008%of the total variance and there are strong positive correlations between various pairs of heavy metals.The total potential ecological risk index(309.599)in the study area is high.Non-carcinogenic risk suggests that there may be long-term health impacts on people who work in the mining areas due to chronic exposure to the environment.Based on the study,the hazard index of carcinogenic health risks associated with heavy metals through ingestion is 520.00×10^(–4).Dermal contact from As and Cr also increases the risk of cancer,with the highest hazard index value of 18.40×10^(–4).The lowest exposure pathway,with the hazard index value of 0.68×10^(–4),indicates that the inhalation of heavy metals has a comparatively low risk of cancer.This study recommends the formulation of policies to monitor the Ijero-Ekiti mining site and other regions in Nigeria where indiscriminate artisanal gold mining activities exist.
基金The authors are grateful to the Telematics Engineering Group(GIT)and the Research Group for Rural Development(Tull)of the University of Cauca,and the Ministry of Science Technology and Innovation of Colombia(Minciencias)for the Ph.D.support granted to Cristian Valencia Payan,as well as the Project“Estrategias para la valorización de los dulces tradicionales de Popayán”(Código:110380863995)founded by Minciencias-Colombia(Contrato 127-2019).
文摘Traditionally,food sustainability has been considered solely in the stage of agricultural production.However,globalization,the expansion of the food production industry,and the emergence of supermarket chains that control the retail food market require specific significant changes in supply chains in the food sector and,therefore,we need to address the economic,social,and environmental impacts of these events.On the other hand,social selling has increased rapidly in recent years,with a further boom,following current events related to the coronavirus disease(COVID-19).This explosion of social sales,where there are usually no control and regulation entities,can bring problems associated with mishandling items.In this paper,we expose how Blockchain technology supports the traceability of social sales by validating the data provided by the chain participants such as digital health passports,production and transport data in the sale process;the proposed solution generates recommendations on productmanagement considering the agreements previously made by the network actors.To evaluate the proposed smart contracts,we useHyperledger Caliper,obtaining an average throughput of 12.6 transactions per second and an average latency of 0.3 s for the asset update process.We also use a study case to evaluate the proposed project platform’s selling-transport stage using Internet of Things(IoT)sensors.
文摘The majority of the population of Burkina Faso lives from agriculture and therefore depends on the land. The main objective of this study is to assess the quality of the soils in the area linked to artisanal mining activities. The methodology adopted consisted in sampling and characterizing the main types of soil. In order to assess the level of soil pollution by artisanal mining, parameters such as the geo-accumulation index (Igeo) and the contamination factor (CF) are calculated. A prediction of acid mine drainage (AMD) was also carried out on samples of mine tailings which are potential sources of pollution of these soils. The results obtained show that the soils in Yimiougou are of nil to low agronomic interest. The Igeo shows that for lead, copper, zinc and arsenic the levels found in the different morphological units are partly attributable to human action and specifically artisanal mining. The values of the contamination factor indicate contamination. Cobalt presents the lowest contamination. For cadmium, the different types of soil are moderately contaminated except for the FITLC type, which has a CF value of 0.50, therefore synonymous with low or absent contamination. The various morphological units studied are very heavily contaminated with zinc, copper, lead and arsenic. The pH and conductivity values indicate that the mine tailings samples are non-acidogenic, therefore not yet oxidized. As for the sulphide contents, they show that only samples S17, S22, S23 and S24 present values that are strictly above the threshold (0.3%) and therefore potentially acid-generating. The comparative study of the acid potential (AP) and the neutralization potential (NP) reveals that the neutralization potentials of the different samples are clearly higher than the acid potentials even for the samples which present a proven acidification potential (S17, S22, S23 and S24). These results show that the mine tailings have the natural capacity to neutralize any possible mine drainage, given the presence of acid-eating minerals such as the carbonates associated with the mineralization.
文摘Maritime safety equipment allows to prevent and minimize the risks inherent to navigation at sea. However, in the artisanal maritime fishery in Gabon, fishermen are confronted with the major difficulty of the inaccessibility of protective tools to carry out fishing trips in all peace of mind. The absence of equipment to help maritime navigation poses the problem of insecurity in which the various artisanal fishermen work, often victims of numerous accidents at sea. This article aims at highlighting the difficulties of accessibility, by the fishermen, of all the conventional protection tools recommended by the administrations. In fact, the methodology used is based on the consultation of official reports and publications on the subject, field observations and semi-structured interviews with 110 actors. The results obtained reveal, on the one hand, a plethora of conventional protective equipment required of fishing vessels. On the other hand, they reveal the high cost of safety equipment which creates, among the professionals concerned, a reluctance to acquire all of the said tools and forces the interested parties to associate them very often with the traditional procedures for rescue at sea.
文摘Active restoration is a critical component of biodiversity conservation for degraded tropical forest ecosystems caused by artisanal gold mining, and the success of restoration is dependent on native species selection. However, significant knowledge gaps exist regarding when and where to plant trees. This article reports on a revegetation trial undertaken in St Elizabeth, Mahdia, Guyana, to assess the survival and RGR (Relative Growth Rate) of three native woody trees and shrubs planted within three years old Acacia mangium Willd trees pruned and unpruned blocks. ANOVA (Analysis of Variance) for a completely randomized block design with four blocks, two pruned and two unpruned, within A. mangium plots. Biochar treatment was added to the plants during transplanting. Thirty-six (36) wildlings of Humiria balsamifera (Aublet.) (Tauroniro), Goupia glabra Aublet (Kabukalli), and Vismia guianensis (Aublet.) Choisy (Bloodwood) were collected and raised in a tree nursery for two weeks. The native plants were transplanted 3 m apart, survival observations and each seedling’s initial height and diameter were measured and recorded. After the experiment, 13% of seedlings from a population of 720 had died, with the highest mortality being experienced at the 92 days of the experiment (t ≤ 122 days). While the overall survival rates were high, emphasizing the importance of field trials on native and exotic species in different environments is essential to fill the knowledge gaps on suitable species for restoration in degraded areas with other land use histories.
基金This study was part of“The Investigation and Research of the Inscriptions Left by Visitors in the Past dynasties in Dunhuang Caves”supported by the Western Program of National Social and Scientific Fund(18XKG008).
文摘This paper investigates a unique and interesting archaeological case,namely the newly found inscription copied from Qianzi Wen(The Thousand Character Essay)on the south wall in the main chamber of Mogao cave 9,and analyzes a series of research topics related to the inscription,hoping to thoroughly reveal the historical and cultural phenomenon of the high popularity and extensive spread of Qianzi Wen in the Tang dynasty,and attempt to restore some living scenes of ancient school students and cave-making artisans.To the best of our knowledge,this is the first time to find Qianzi Wen on the wall in Mogao caves.
基金Under the auspices of the National Natural Science Foundation of China(No.4067305941772236)+1 种基金the 13th Five Years Research Project for Science and Technology of Education Department(No.JJKH20170922KJJJKH20170920KJ)
文摘The Jiapigou gold mine area, located in the upper reaches of the Songhua River, was the first and largest artisanal gold mine once in China, and it used to be prominent in two marking years(1870 and 1974). Jiapigou area had a gold mining history of more than 190 years, which was first opened in 1820. Gold extraction with algamation was applied as the dominant method of excavation from 1940 to 2008, and a total of more than 100 t of gold were extracted from the mine using this method and it was estimated that 100–200 t Hg were released, thus causing severe mercury environmental pollution in the mining area. In the experimental campaigns of this study, in situ air and soil Hg concentrations and air-soil Hg fluxes were measured from April 2009 to December 2011. The results showed that in the study area the total gaseous mercury(TGM) concentration exhibited remarkable spatial and temporal distribution patterns, i.e. the TGM gradually decreased following the increase in distance to gold mining sites in space, and the values in spring, summer and autumn were elevated by 1–2 orders of magnitude in comparison with those in winter. Furthermore, at other sampling sites the total soil mercury(TSM) concentration in spring was higher than that in autumn, except for the contrary laws demonstrated at the Erdaogou mining site. However, in spring and winter the Hg flux between air and soil was under the control of different environmental factors, and the characteristics were clear and distinct. In spring the Hg flux between air and soil was directly under the control of solar irradiation, and the releasing process was predominant with a remarkable positive correlation to solar irradiation. Nevertheless, in winter the Hg fluxes were indirectly under the control of solar irradiation, which caused thermal inversion due to the thick snow cover. The depositing process was predominant and the correlations between Hg flux and air temperature was remarkably negative, and there was a positive correlation between Hg flux and solar irradiation.
文摘AIM： To evaluate the effect of incision types for Artisan phakic intraocular lens （PIOL） implantation on ocular higher-order aberrations （HOAs）.METHODS： A retrospective review was conducted of the patients who had undergone Artisan PIOL implantation for the correction of myopia and followed up for at least 6mo. Patients are classified into 2 groups considering the incision type： cornea group with patients undergone clear corneal incision; sclera group with patients undergone sclera tunnel incision. All patients with postoperative astigmatism of under 1 diopter （D） were included to minimize the effect of residual astigmatism on postoperative HOAs. Visual acuity, special equivalents, astigmatism, predictability （±1 D from target refraction）, HOAs （coma, trefoil, spherical aberration）, and corneal endothelial counts were analyzed preoperatively and 6mo postoperatively.RESULTS： At the postoperative 6mo, all patients of both groups achieved uncorrected visual acuity of 16/20 or better, and significantly decreased the spherical equivalents compared with preoperative values. The predictability of refractive correction was 96% in the former, and 94% in the latter. Unlike the sclera group, preoperative astigmatism decreased significantly in cornea group at postoperative 6mo. The HOAs increased significantly at postoperative 6mo compared to the preoperative values in both groups, and the root mean square （RMS） total and trefoil wavefront aberration of cornea group were significantly higher than those of sclera group.CONCLUSION： Although corneal incision significantly reduces preexisting astigmatism, the postoperative 6mo of total RMS and trefoil aberration change may deteriorate the visual quality after Artisan PIOL implantation.
文摘Artisanal gold mining in local communities is on the increase. This has led to concerns about mercury pollution resulting from these mining activities. This study was conducted to assess the level of mercury pollution in rivers and streams around artisanal gold mining areas of the Birim North District of Ghana. Rivers, streams, sediments and boreholes were sampled to determine total mercury levels during the wet and dry seasons and to explore the potential impact of the mercury levels on water quality in the area. The results show that the total mercury concentrations measured upstream were significantly lower than concentrations in samples taken downstream. Also, the total mercury concentrations measured in the stream water samples in both seasons exceeded the WHO guideline limit (1.0 μg/L) for drinking water. However, one downstream total mercury concentration exceeded the guideline limit in the dry season. The total mercury concentrations in sediments upstream and downstream in both seasons exceeded the US-EPA guideline value of 0.2 mg/kg. The boreholes in the study area have total mercury concentrations exceeding the WHO guideline limit during both seasons. Total mercury concentrations in the boreholes in the wet season were lower than the dry season.
