142 research outputs found

    A remote sensing approach for regional-scale mapping of agricultural land-use systems based on NDVI time series.

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    In response to the need for generic remote sensing tools to support large-scale agricultural monitoring, we present a new approach for regional-scale mapping of agricultural land-use systems (ALUS) based on object-based Normalized Difference Vegetation Index (NDVI) time series analysis. The approach consists of two main steps. First, to obtain relatively homogeneous land units in terms of phenological patterns, a principal component analysis (PCA) is applied to an annual MODIS NDVI time series, and an automatic segmentation is performed on the resulting high-order principal component images. Second, the resulting land units are classified into the crop agriculture domain or the livestock domain based on their land-cover characteristics. The crop agriculture domain land units are further classified into different cropping systems based on the correspondence of their NDVI temporal profiles with the phenological patterns associated with the cropping systems of the study area. A map of the main ALUS of the Brazilian state of Tocantins was produced for the 2013-2014 growing season with the new approach, and a significant coherence was observed between the spatial distribution of the cropping systems in the final ALUS map and in a reference map extracted from the official agricultural statistics of the Brazilian Institute of Geography and Statistics (IBGE). This study shows the potential of remote sensing techniques to provide valuable baseline spatial information for supporting agricultural monitoring and for large-scale land-use systems analysis

    The potential for remote sensing and hydrologic modelling to assess the spatio-temporal dynamics of ponds in the Ferlo Region (Senegal)

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    In the Ferlo Region in Senegal, livestock depend on temporary ponds for water but are exposed to the Rift Valley Fever (RVF), a disease transmitted to herds by mosquitoes which develop in these ponds. Mosquito abundance is related to the emptying and filling phases of the ponds, and in order to study the epidemiology of RVF, pond modelling is required. In the context of a data scarce region, a simple hydrologic model which makes use of remote sensing data was developed to simulate pond water dynamics from daily rainfall. Two sets of ponds were considered: those located in the main stream of the Ferlo Valley whose hydrological dynamics are essentially due to runoff, and the ponds located outside, which are smaller and whose filling mechanisms are mainly due to direct rainfall. Separate calibrations and validations were made for each set of ponds. Calibration was performed from daily field data (rainfall, water level) collected during the 2001 and 2002 rainy seasons and from three different sources of remote sensing data: 1) very high spatial resolution optical satellite images to access pond location and surface area at given dates, 2) Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Digital Elevation Model (DEM) data to estimate pond catchment area and 3) Tropical Rainfall Measuring Mission (TRMM) data for rainfall estimates. The model was applied to all ponds of the study area, the results were validated and a sensitivity analysis was performed. Water height simulations using gauge rainfall as input were compared to water level measurements from four ponds and Nash coefficients >0.7 were obtained. Comparison with simulations using TRMM rainfall data gave mixed results, with poor water height simulations for the year 2001 and good estimations for the year 2002. A pond map derived from a Quickbird satellite image was used to assess model accuracy for simulating pond water areas for all the ponds of the study area. The validation showed that modelled water areas were mostly underestimated but significantly correlated, particularly for the larger ponds. The results of the sensitivity analysis showed that parameters relative to pond shape and catchment area estimation have less effects on model simulation than parameters relative to soil properties (rainfall threshold causing runoff in dry soils and the coefficient expressing soil moisture decrease with time) or the water loss coefficient. Overall, our results demonstrate the possibility of using a simple hydrologic model with remote sensing data to track pond water heights and water areas in a homogeneous arid area

    Spatio-temporal patterns and landscape-associated risk of Buruli ulcer in Akonolinga, Cameroon

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    Background: Buruli ulcer (BU) is an extensively damaging skin infection caused by Mycobacterium ulcerans, whose transmission mode is still unknown. The focal distribution of BU and the absence of interpersonal transmission suggest a major role of environmental factors, which remain unidentified. This study provides the first description of the spatio-temporal variations of BU in an endemic African region, in Akonolinga, Cameroon. We quantify landscape-associated risk of BU, and reveal local patterns of endemicity. Methodology/Principal Findings: From January 2002 to May 2012, 787 new BU cases were recorded in 154 villages of the district of Akonolinga. Incidence per village ranged from 0 (n = 59 villages) to 10.4 cases/1000 person. years (py); median incidence was 0.4 cases/1,000py. Villages neighbouring the Nyong River flood plain near Akonolinga town were identified as the highest risk zone using the SPODT algorithm. We found a decreasing risk with increasing distance to the Nyong and identified 4 time phases with changes in spatial distribution. We classified the villages into 8 groups according to landscape characteristics using principal component analysis and hierarchical clustering. We estimated the incidence ratio (IR) associated with each landscape using a generalised linear model. BU risk was highest in landscapes with abundant wetlands, especially cultivated ones (IR = 15.7, 95% confidence interval [95% CI] = 15.7[4.2-59.2]), and lowest in reference landscape where primary and secondary forest cover was abundant. In intermediate-risk landscapes, risk decreased with agriculture pressure (from IR[95% CI] = 7.9[2.2-28.8] to 2.0[0.6-6.6]). We identified landscapes where endemicity was stable and landscapes where incidence increased with time. Conclusion/Significance: Our study on the largest series of BU cases recorded in a single endemic region illustrates the local evolution of BU and identifies the Nyong River as the major driver of BU incidence. Local differences along the river are explained by wetland abundance and human modification of the environment

    До питання про співвідношення праворозуміння та правової думки

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    У статті проаналізовано структуру праворозуміння, дано визначення поняття правова думка та вказано, що праворозуміння, як осмислення правової дійсності є складовою частиною правової думки.В статье проанализировано структуру правопонимания, дано определение понятия правовая мысль иопределено, что правопонимание как осмысление правовой действительности является составляющей правовой мысли.In the article are analyzed the structure of legal understanding, given the definition of legal thought and determined that the legal comprehension as a legal interpretation of reality is a part of legal thought

    Combining hydrology and mosquito population models to identify the drivers of Rift Valley fever emergence in semi-arid regions of West Africa

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    BACKGROUND: Rift Valley fever (RVF) is a vector-borne viral zoonosis of increasing global importance. RVF virus (RVFV) is transmitted either through exposure to infected animals or through bites from different species of infected mosquitoes, mainly of Aedes and Culex genera. These mosquitoes are very sensitive to environmental conditions, which may determine their presence, biology, and abundance. In East Africa, RVF outbreaks are known to be closely associated with heavy rainfall events, unlike in the semi-arid regions of West Africa where the drivers of RVF emergence remain poorly understood. The assumed importance of temporary ponds and rainfall temporal distribution therefore needs to be investigated. METHODOLOGY/PRINCIPAL FINDINGS: A hydrological model is combined with a mosquito population model to predict the abundance of the two main mosquito species (Aedes vexans and Culex poicilipes) involved in RVFV transmission in Senegal. The study area is an agropastoral zone located in the Ferlo Valley, characterized by a dense network of temporary water ponds which constitute mosquito breeding sites. The hydrological model uses daily rainfall as input to simulate variations of pond surface areas. The mosquito population model is mechanistic, considers both aquatic and adult stages and is driven by pond dynamics. Once validated using hydrological and entomological field data, the model was used to simulate the abundance dynamics of the two mosquito species over a 43-year period (1961–2003). We analysed the predicted dynamics of mosquito populations with regards to the years of main outbreaks. The results showed that the main RVF outbreaks occurred during years with simultaneous high abundances of both species. CONCLUSION/SIGNIFICANCE: Our study provides for the first time a mechanistic insight on RVFV transmission in West Africa. It highlights the complementary roles of Aedes vexans and Culex poicilipes mosquitoes in virus transmission, and recommends the identification of rainfall patterns favourable for RVFV amplification

    Visual field progression 8 years after trabeculectomy in Asian eyes: results from The Singapore 5-Fluorouracil Study

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    Background/Aims: This work aimed to study the effect of long-term intraocular pressure (IOP) fluctuation on visual field (VF) progression 8 years post-trabeculectomy in Asian eyes. / Methods: This was a retrospective analysis of 8-year post-trabeculectomy data from The Singapore 5-Fluorouracil (5-FU) Study. VFs were analysed using Progressor software (Medisoft, Leeds, UK). Outcome measures included mean slope for VF per year, number of progressing points and mean slope for progressing points per year. Multivariate regression analyses were performed adjusting for age, gender, ethnicity, glaucoma type, intraoperative 5-FU, diabetes mellitus, hypertension, best pre-trabeculectomy VF mean deviation, post-trabeculectomy mean IOP, IOP reduction and IOP fluctuation (SD of IOPs at 6-monthly timepoints). / Results: 127 (52.3%) subjects completed 8-year follow-up with ≥5 reliable VFs and ≥8 6-monthly IOP measurements. Mean age was 61.8±9.6 years. Post-operatively, mean IOP was 14.2±2.8 mm Hg and mean IOP fluctuation was 2.53±1.20 mm Hg. Higher IOP fluctuation was associated with greater mean slope for field (B=−0.071; p=0.013), number of progressing points (B=0.963; p=0.014) and VF progression as defined by ≥1 progressing point (OR=1.585; p=0.029). There was also a trend towards eyes with higher IOP fluctuation having ≥3 adjacent progressing points in the same hemifield (OR=1.489; p=0.055). Greater mean IOP reduction post-trabeculectomy was associated only with a lower mean slope for progressing points per year (B=−0.026; p=0.028). There was no significant effect of intra-operative 5-FU compared with placebo for all outcome measures. / Conclusion: In post-trabeculectomy Asian eyes with well-controlled IOP, higher long-term IOP fluctuation may be associated with greater VF progression

    Ecological niche modelling of Hemipteran insects in Cameroon ; the paradox of a vector-borne transmission for Mycobacterium ulcerans, the causative agent of Buruli ulcer

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    Background: The mode of transmission of the emerging neglected disease Buruli ulcer is unknown. Several potential transmission pathways have been proposed, such as amoebae, or transmission through food webs. Several lines of evidence have suggested that biting aquatic insects, Naucoridae and Belostomatidae, may act as vectors, however this proposal remains controversial. Materials and methods: Herein, based on sampling in Cameroon, we construct an ecological niche model of these insects to describe their spatial distribution. We predict their distribution across West Africa, describe important environmental drivers of their abundance, and examine the correlation between their abundance and Buruli ulcer prevalence in the context of the Bradford-Hill guidelines. Results: We find a significant positive correlation between the abundance of the insects and the prevalence of Buruli ulcer. This correlation changes in space and time, it is significant in one Camerounese study region in (Akonolinga) and not other (Bankim). We discuss notable environmental differences between these regions. Conclusion: We interpret the presence of, and change in, this correlation as evidence (though not proof) that these insects may be locally important in the environmental persistence, or transmission, of Mycobacterium. ulcerans. This is consistent with the idea of M. ulcerans as a pathogen transmitted by multiple modes of infection, the importance of any one pathway changing from region to region, depending on the local environmental conditions

    住み込み女中ハナ・カルウィックが観たパイロンの悲劇『サルダナパラス』

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    In 1854 Hannah Cullwick, a 21-year-old Victorian maid-servant, met a 26-year-old gentleman named Arthur Munby on the Oxford Street in London. They fell in love with each other on the spot and started an unusual master-slave relationship crossing the class barrier between them. Later they secretly got married without being known to anybody except Hannah's close relatives. Munby, an upper-middle class gentleman, was interested in working class women and it was his favorite pastime to find hard-working women and talk to them. Hannah was one of his findings, so to speak. On the other hand, Hannah also had a reason to be attracted to Munby. She was looking for a man for whom she could serve as a slave. What made Hannah earnestly interested in becoming somebody's slave was a popular stage play that Hannah had seen in her spare time one year before they met. The play was Lord George Gordon Byron's historic tragedy, Sardanapalus, which depicts a feminine, peace-loving King of ancient Nineveh and the decline and collapse of the Assirian Empire in one night. It also depicts a love story between the king Sardanapalus and a slave woman, Myrrah. Hannah was very impressed with the love between the king and the slave, and identified herself with the slave. So, it may be said that the stage play eventually changed her life. This paper discusses what qualities of the play, Sardanapalus, Hannah and many other Victorians were impressed with most and how the tragic impression was created by the story or the death of the feminine king Sardanapalus. It also discusses the historical and social background of the play from which it was produced and the reasons why it could receive such high reputation and popularity among the Victorians. This paper focuses on the characteristics of the slave, Myrrah, considering her background both as an Ionian and as a Greek. We can hypothesize that Hannah was particularly attracted to the slave Myrrah's deep democratic values, and the uniqueness of her trying to influence the king Sardanapalus, which came from her Greek origin. This paper speculates that it was this heroism that inspired not only Hannah but also countless Victorians
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