comparative assessment

比较评估
  • 文章类型: Journal Article
    背景:在线药房市场正在增长,合法的网上药店提供便利和可访问性等优势。然而,这种增加的需求吸引了恶意行为者进入这个领域,导致非法供应商的扩散,这些供应商使用欺骗性技术在搜索结果中排名更高,并通过分发不合格或伪造的药物构成严重的公共卫生风险。搜索引擎提供商已经开始将生成式人工智能(AI)集成到搜索引擎界面中,它可以通过用户友好的体验提供更个性化的结果来彻底改变搜索。然而,这些新技术的不当整合会带来潜在风险,并可能会无意中将用户引向非法供应商,从而进一步加剧非法在线药房带来的风险。
    目标:生成AI集成在重塑搜索引擎结果中的作用,特别是与网上药店有关的,尚未研究。我们的目标是确定,确定患病率,并在AI生成的搜索结果和建议中描述非法的在线药房建议。
    方法:我们从Google的搜索生成体验(SGE)和MicrosoftBing的聊天中对AI生成的建议进行了比较评估,专注于代表多种治疗类别的流行和知名药物,包括受控物质。网站被单独检查以确定合法性,通过与全国药房委员会协会和LegitScript数据库的交叉引用,确定了已知的非法供应商。
    结果:在AI生成的搜索结果中推荐的262个网站中,47.33%(124/262)属于活跃的网上药店,31.29%(82/262)导致合法。然而,19.04%(24/126)的BingChat和13.23%(18/136)的GoogleSGE建议将用户引向非法供应商,包括受控物质。非法药房的比例因药物和搜索引擎而异。搜索引擎之间非法网站的分布存在显着差异。与GoogleSGE(6/92,6%)相比,BingChat(21/86,24%)中导致非法在线药店销售处方药的链接患病率明显更高(P=.001)。关于受控物质的建议,Google提出的建议导致流氓卖家的数量(12/44,27%;P=0.02)明显高于必应(3/40,7%)。
    结论:虽然将生成AI集成到搜索引擎中具有很好的潜力,这也带来了巨大的风险。这是第一项研究,揭示了这些平台中的漏洞,同时强调了与无意中推广非法药房相关的潜在公共卫生影响。我们发现AI生成的建议中有一个令人担忧的比例导致了非法的网上药店,这不仅可能会增加他们的交通,还会进一步加剧现有的公共卫生风险。在生成搜索中迫切需要严格的监督和适当的保障措施,以减轻消费者风险。确保积极引导用户到经过验证的药房,并优先考虑合法来源,同时将非法供应商排除在推荐之外。
    BACKGROUND: The online pharmacy market is growing, with legitimate online pharmacies offering advantages such as convenience and accessibility. However, this increased demand has attracted malicious actors into this space, leading to the proliferation of illegal vendors that use deceptive techniques to rank higher in search results and pose serious public health risks by dispensing substandard or falsified medicines. Search engine providers have started integrating generative artificial intelligence (AI) into search engine interfaces, which could revolutionize search by delivering more personalized results through a user-friendly experience. However, improper integration of these new technologies carries potential risks and could further exacerbate the risks posed by illicit online pharmacies by inadvertently directing users to illegal vendors.
    OBJECTIVE: The role of generative AI integration in reshaping search engine results, particularly related to online pharmacies, has not yet been studied. Our objective was to identify, determine the prevalence of, and characterize illegal online pharmacy recommendations within the AI-generated search results and recommendations.
    METHODS: We conducted a comparative assessment of AI-generated recommendations from Google\'s Search Generative Experience (SGE) and Microsoft Bing\'s Chat, focusing on popular and well-known medicines representing multiple therapeutic categories including controlled substances. Websites were individually examined to determine legitimacy, and known illegal vendors were identified by cross-referencing with the National Association of Boards of Pharmacy and LegitScript databases.
    RESULTS: Of the 262 websites recommended in the AI-generated search results, 47.33% (124/262) belonged to active online pharmacies, with 31.29% (82/262) leading to legitimate ones. However, 19.04% (24/126) of Bing Chat\'s and 13.23% (18/136) of Google SGE\'s recommendations directed users to illegal vendors, including for controlled substances. The proportion of illegal pharmacies varied by drug and search engine. A significant difference was observed in the distribution of illegal websites between search engines. The prevalence of links leading to illegal online pharmacies selling prescription medications was significantly higher (P=.001) in Bing Chat (21/86, 24%) compared to Google SGE (6/92, 6%). Regarding the suggestions for controlled substances, suggestions generated by Google led to a significantly higher number of rogue sellers (12/44, 27%; P=.02) compared to Bing (3/40, 7%).
    CONCLUSIONS: While the integration of generative AI into search engines offers promising potential, it also poses significant risks. This is the first study to shed light on the vulnerabilities within these platforms while highlighting the potential public health implications associated with their inadvertent promotion of illegal pharmacies. We found a concerning proportion of AI-generated recommendations that led to illegal online pharmacies, which could not only potentially increase their traffic but also further exacerbate existing public health risks. Rigorous oversight and proper safeguards are urgently needed in generative search to mitigate consumer risks, making sure to actively guide users to verified pharmacies and prioritize legitimate sources while excluding illegal vendors from recommendations.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    遗传改良主要取决于群体中存在的遗传变异水平,种群的遗传多样性程度在很大程度上决定了遗传发展的速度。为了分析遗传多样性和确定品种身份,分子标记是一种有用的工具。使用30个SSR(简单序列重复)和30个RAPD(随机扩增多态性DNA)标记,本研究对17个芒果品种的遗传差异进行了评价。使用两种标记系统的遗传多样性特征评估了它们的有效性。此外,评估了SM(简单匹配)和Dice相似系数及其对芒果聚类的影响。结果表明,SSR标记产生192个等位基因,所有这些都是多态的(100%)。用RAPD标记,获得434个条带,其中多态性361(83%)。RAPD和SSR的平均多态性信息含量(PIC)分别为0.378和0.735。与RAPD标记相比,使用SSR标记可获得更高的其他遗传多样性参数值。此外,根据两个相似系数对基因型进行分组,而不详细考虑这些系数不会影响研究结果。RAPD标记OPA_01,OPM_12,然后是OPO_12和SSR标记MIAC_4,MIAC_5,然后是mMiCIR_21,在描述所研究品种之间的遗传变异方面信息最丰富;它们可用于进一步的研究,例如遗传作图或标记辅助选择。总的来说,“Zebda”品种是所研究品种中最多样化的品种。
    Genetic improvement mainly depends on the level of genetic variability present in the population, and the degree of genetic diversity in a population largely determines the rate of genetic advancement. For analyzing genetic diversity and determining cultivar identities, a molecular marker is a useful tool. Using 30 SSR (simple sequence repeat) and 30 RAPD (randomly amplified polymorphic DNA) markers, this study evaluated the genetic divergence of 17 mango cultivars. The effectiveness of the two marker systems was evaluated using their genetic diversity characteristics. Additionally, the effects of SM (simple matching) and Dice similarity coefficients and their effects on mango clustering were evaluated. The findings showed that SSR markers generated 192 alleles, all of which were polymorphic (100%). With RAPD markers, 434 bands were obtained, 361 of which were polymorphic (83%). The average polymorphic information content (PIC) for RAPD and SSR was 0.378 and 0.735, respectively. Using SSR markers resulted in much higher values for other genetic diversity parameters compared to RAPD markers. Furthermore, grouping the genotypes according to the two similarity coefficients without detailed consideration of these coefficients could not influence the study results. The RAPD markers OPA_01, OPM_12 followed by OPO_12 and SSR markers MIAC_4, MIAC_5 followed by mMiCIR_21 were the most informative in terms of describing genetic variability among the cultivars under study; they can be used in further investigations such as genetic mapping or marker-assisted selection. Overall, \'Zebda\' cultivar was the most diverse of the studied cultivars.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    在这项研究中,生物基燃料在涡轮喷气发动机的利用是全面监测与适应各种有用的指标的研究范围的基础上热力学原理。在这方面,广泛的能量和火用,热生态学,环境,对喷气煤油燃料和生物基燃料燃料的涡轮喷气发动机进行了环境经济和可持续性分析。根据主要发现,当发动机由生物燃料驱动时,燃烧排放的质量流测为4.547kgs-1。对于喷气煤油动力的情况,比油耗和比推力确定为0.13kgkN-1s-1和147.81kNskg-1。而对于生物燃料动力的情况,它们的计算方法为0.15kgkN-1s-1和148.23kNskg-1。如果选择生物燃料而不是喷气煤油燃料,观察到发动机具有18.18%的更好的能量效率性能。对于喷气煤油使用条件,发动机的环境影响因子值为4.88,而生物燃料利用案例为4.93。对于喷射煤油使用条件,总排放的CO2排放量为336,672kg-CO2year-1,而生物燃料利用案例估计为222,012千克二氧化碳1年。此外,只要选择生物燃料作为喷气煤油的替代品,环境破坏成本流,即发动机的环境经济参数,从第1年的59,254.27美元降至第1年的39,074.11美元。观察到,对于喷气煤油和生物燃料利用情况,空气压缩机组件的可持续效率因子和可持续发展指数输出是相同的。分别为8.31和7.31。
    In this study, utilization of a bio-based fuel in a turbojet engine is comprehensively monitored with adapting various useful indicators for the scope of the study based on thermodynamic principles. In this regard, extensive energy and exergy, thermoecologic, environmental, enviroeconomic and sustainability analyses are performed for both the turbojet engines fueled by jet kerosene and fueled by a bio-based fuel. As per the main findings, the mass stream of combustion emissions is measured to be 4.547 kg s-1, when the engine is powered by biofuel. The specific fuel consumption and specific thrust are determined as 0.13 kg kN-1 s-1 and 147.81 kNs kg-1 for jet kerosene-powered case, while they are calculated as 0.15 kg kN-1 s-1 and 148.23 kNs kg-1 for biofuel-powered case. If biofuel is selected over jet-kerosene fuel, it is observed that the engine has better energy efficiency performance by 18.18%. The engine\'s environmental effect factor value is found as 4.88 for jet-kerosene usage condition, while it is found to be 4.93 for biofuel utilization case. The overall emitted CO2 emissions is measured as 336,672 kg-CO2 year-1 for jet-kerosene usage condition, while it is estimated as 222,012 kg-CO2 year-1 for the biofuel utilization case. Also, as far as biofuel is chosen as alternative to jet-kerosene, the environmental damage cost stream, namely the enviroeconomic parameter of the engine, falls from 59,254.27 US$ year-1 to 39,074.11 US$ year-1. It is observed that sustainable efficiency factor and exergetic sustainability index outputs of the components of air compressor are the same for jet-kerosene and biofuel utilization cases, which are 8.31 and 7.31, respectively.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    本文对正在进行的COVID-19大流行的第一波和第二波对美国股市的影响及其不确定性进行了首次比较评估。为此,我们研究了在COVID-19危机之前和期间,冲击对中美股市相关性的动态条件相关性和不对称影响。此外,我们分析并比较了COVID-19大流行与美国在第一和第二波大流行期间的回报和不确定性之间的关系.首先,我们发现动态相关方法支持两个股票市场之间存在波动溢出(传染效应),特别是在COVID-19在美国的快速传播阶段。第二,对新闻冲击相关面的分析表明,中美市场的冲击对两个市场的相关性具有不对称的影响。最后,我们发现美国回报之间存在持续的联系,不确定性,以及第一波和第二波爆发期间的COVID-19大流行。我们的结果证明,大流行对整个金融市场,特别是美国经济显示出有害后果。
    This paper makes the first comparative assessment of the impacts of the first and second waves of the ongoing COVID-19 pandemic for the US stock market and its uncertainty. To this end, we investigate the dynamic conditional correlation and the asymmetric impacts of shocks on the correlation between the US and Chinese stock markets before and during the COVID-19 crisis. Furthermore, we analyze and compare the relationship between the COVID-19 pandemic and US returns and uncertainty during the first and second waves of the pandemic. First, we find that the dynamic correlation approach supports the presence of volatility spillovers (contagion effects) between the two stock markets, especially during the rapid spread phase of COVID-19 in the US. Second, the analysis of news impact correlation surfaces shows that the shocks to the US and Chinese markets have asymmetric effects on the correlation between the two markets. Finally, we find a persistent link between US returns, uncertainty, and the COVID-19 pandemic during the first and second waves of the outbreak. Our results prove that the pandemic has shown harmful consequences for financial markets in general and the US economy in particular.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

       PDF(Pubmed)

  • 文章类型: Journal Article
    UNASSIGNED:食管鳞状细胞癌(ESCC)的大体肿瘤体积(GTV)的准确定义可以促进精确的照射场测定,并进一步达到放疗的疗效。这项回顾性研究旨在评估利用基于深度学习的方法从诊断为ESCC的患者的3D18F-FDGPET/CT图像自动定义GTV的适用性。
    UNASSIGNED:我们对临床队列进行了164次18F-FDGPET/CT扫描实验。首先采用最先进的食管GTV分割深度神经网络来描绘PET/CT图像上的病变区域。之后,我们提出了一种新颖的等效截顶椭锥积分法(ETECIM)来估计GTV值。骰子相似系数(DSC)指标,Hausdorff距离(HD),和平均表面距离(MSD)用于评估分割性能。符合性指数(CI),包容度(DI),和运动矢量(MV)用于评估预测和地面实况肿瘤之间的差异。GTV的统计差异,DI,位置也是确定的。
    UNASSIGNED:我们进行4倍交叉验证以进行评估,报告DSC的值,HD,MSD为0.72±0.02,11.87±4.20mm,和2.43±0.60mm(平均值±标准偏差),分别。对于每个倍数交叉验证,皮尔逊相关性(R2)达到0.8434、0.8004、0.9239和0.7119,预测和地面真值GTT之间没有显着差异(t=1.193,p=0.235)。对于DI,发现显著差异(t=-2.263,p=0.009)。对于职位评估,预测和地面真实GTT之间没有显着差异(x方向的左右:t=0.102,p=0.919,y方向的前后:t=0.221,p=0.826,z方向的颅尾:t=0.569,p=0.570)。CI的中位数为0.63,得到的MV很小。
    UNASSIGNED:预测的肿瘤与手动地面实况非常吻合。所提出的GTV估计方法ETECIM比最常用的体素体积求和方法更精确。由于与预测结果具有良好的线性相关性,因此可以求解出地面实况GTT。基于深度学习的方法在GTV定义和临床放射治疗中显示出其广阔的应用前景。
    UNASSIGNED: The accurate definition of gross tumor volume (GTV) of esophageal squamous cell carcinoma (ESCC) can promote precise irradiation field determination, and further achieve the radiotherapy curative effect. This retrospective study is intended to assess the applicability of leveraging deep learning-based method to automatically define the GTV from 3D 18F-FDG PET/CT images of patients diagnosed with ESCC.
    UNASSIGNED: We perform experiments on a clinical cohort with 164 18F-FDG PET/CT scans. The state-of-the-art esophageal GTV segmentation deep neural net is first employed to delineate the lesion area on PET/CT images. Afterwards, we propose a novel equivalent truncated elliptical cone integral method (ETECIM) to estimate the GTV value. Indexes of Dice similarity coefficient (DSC), Hausdorff distance (HD), and mean surface distance (MSD) are used to evaluate the segmentation performance. Conformity index (CI), degree of inclusion (DI), and motion vector (MV) are used to assess the differences between predicted and ground truth tumors. Statistical differences in the GTV, DI, and position are also determined.
    UNASSIGNED: We perform 4-fold cross-validation for evaluation, reporting the values of DSC, HD, and MSD as 0.72 ± 0.02, 11.87 ± 4.20 mm, and 2.43 ± 0.60 mm (mean ± standard deviation), respectively. Pearson correlations (R2) achieve 0.8434, 0.8004, 0.9239, and 0.7119 for each fold cross-validation, and there is no significant difference (t = 1.193, p = 0.235) between the predicted and ground truth GTVs. For DI, a significant difference is found (t = -2.263, p = 0.009). For position assessment, there is no significant difference (left-right in x direction: t = 0.102, p = 0.919, anterior-posterior in y direction: t = 0.221, p = 0.826, and cranial-caudal in z direction: t = 0.569, p = 0.570) between the predicted and ground truth GTVs. The median of CI is 0.63, and the gotten MV is small.
    UNASSIGNED: The predicted tumors correspond well with the manual ground truth. The proposed GTV estimation approach ETECIM is more precise than the most commonly used voxel volume summation method. The ground truth GTVs can be solved out due to the good linear correlation with the predicted results. Deep learning-based method shows its promising in GTV definition and clinical radiotherapy application.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    UNASSIGNED: Despite increasing interest in whole-slide imaging (WSI) over optical microscopy (OM), limited information on comparative assessment of various digital pathology systems (DPSs) is available.
    UNASSIGNED: A comprehensive evaluation was undertaken to investigate the technical performance-assessment and diagnostic accuracy of four DPSs with an objective to establish the noninferiority of WSI over OM and find out the best possible DPS for clinical workflow.
    UNASSIGNED: A total of 2376 digital images, 15,775 image reads (OM - 3171 + WSI - 12,404), and 6100 diagnostic reads (OM - 1245, WSI - 4855) were generated across four DPSs (coded as DPS: 1, 2, 3, and 4) using a total 240 cases (604 slides). Onsite technical evaluation revealed successful scan rate: DPS3 < DPS2 < DPS4 < DPS1; mean scanning time: DPS4 < DPS1 < DPS2 < DPS3; and average storage space: DPS3 < DPS2 < DPS1 < DPS4. Overall diagnostic accuracy, when compared with the reference standard for OM and WSI, was 95.44% (including 2.48% minor and 2.08% major discordances) and 93.32% (including 4.28% minor and 2.4% major discordances), respectively. The difference between the clinically significant discordances by WSI versus OM was 0.32%. Major discordances were observed mostly using DPS4 and least in DPS1; however, the difference was statistically insignificant. Almost perfect (κ ≥ 0.8)/substantial (κ = 0.6-0.8) inter/intra-observer agreement between WSI and OM was observed for all specimen types, except cytology. Overall image quality was best for DPS1 followed by DPS4. Mean digital artifact rate was 6.8% (163/2376 digital images) and maximum artifacts were noted in DPS2 (n = 77) followed by DPS3 (n = 36). Most pathologists preferred viewing software of DPS1 and DPS2.
    UNASSIGNED: WSI was noninferior to OM for all specimen types, except for cytology. Each DPS has its own pros and cons; however, DPS1 closely emulated the real-world clinical environment. This evaluation is intended to provide a roadmap to pathologists for the selection of the appropriate DPSs while adopting WSI.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    中国遭遇煤炭消费造成的严重空气污染。中国和欧盟的目标是减少温室气体排放。从残留物转移到沼气有助于解决这两个问题。这项研究评估了中国的沼气潜力和相关的水足迹(WFs),并将结果与欧盟的潜力和WFs进行了比较。从欧盟沼气潜力的文献综述开始,它分析信息,产生一种计算方法,其在中国的验证和应用。最后,它估计了WFs,并对欧盟和中国的沼气潜力进行了比较评估。在欧盟,来自农业的沼气,林业和其他残留物可能占一次能源消费的8%(5300PJ),在中国10%(13275PJ。)在欧盟,农业贡献了41%,林业26%,其他残留23%,和肥料10%。中国的相应结果是农业(67%),林业(23%),粪肥(7%)和其他残留物(3%)。在欧盟,沼气可能占天然气总需求的45%;在中国,2018年沼气产量超过消费量(占需求的185%)。欧盟的结果落在早期研究的残留潜力范围内。玉米,小麦,大麦和油菜对欧盟农业沼气潜力贡献了78%。在中国,主要作物是玉米(49%),大米(18%),小麦(12%)和籽棉(6%)。对于水,特定作物残留物的WF之间存在很大差异,而且在欧盟和中国作物残留物之间。大多数中国作物残留物的WFs比欧盟的残留物更大。来自甜菜残留物的沼气具有最小的WFs,来自烟草残留物的沼气最大。尽管使用残留物作为能源不会改变国家总的WFs,它将WFs重新分配给主要产品和残留物。比较评估支持更好地利用WFs较低的残留物产生的沼气潜力,也适用于其他地区和国家。
    China encounters heavy air pollution caused by coal consumption. China and the EU aim to decrease greenhouse gas emissions. Shifting to biogas from residues contributes to solving both problems. This study assesses China\'s biogas potentials and related water footprints (WFs) and compares results with potentials and WFs for the EU. Starting from a literature review on EU biogas potentials, it analyzes information resulting in a calculation methodology, its validation and application to China. Finally, it estimates WFs and makes a comparative assessment of biogas potentials of the EU and China. In the EU, biogas from agricultural, forestry and other residues might contribute 8% (5300 PJ) to primary energy consumption, in China 10% (13,275 PJ.) In the EU, agriculture contributes 41%, forestry 26%, other residues 23%, and manure 10%. The corresponding results for China are agriculture (67%), forestry (23%), manure (7%) and other residues (3%). In the EU, biogas might contribute 45% to total gas demand; in China more biogas can be produced than consumed in 2018 (185% of demand). The EU results fall in the range of residue potentials from earlier studies. Maize, wheat, barley and rapeseed contribute 78% to the EU agricultural biogas potential. In China, dominant crops are maize (49%), rice (18%), wheat (12%) and seed cotton (6%). For water, there are large differences among WFs of specific crop residues, but also between WFs for EU and Chinese crop residues. Most Chinese crop residues have larger WFs than the EU residues. Biogas from sugar beet residues has the smallest WFs, biogas from tobacco residues the largest. Although using residues for energy does not change total national WFs, it reallocates WFs over main products and residues. The comparative assessment supports better use of biogas potentials from residues with lower WFs and is also applicable for other regions and countries.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

  • 文章类型: Journal Article
    热驱动热泵系统在低品位热能的利用中起着重要作用。为了评估和比较三种不同结构的热驱动热泵和热变压器的性能,本文采用低耗散假设建立了它们的不可逆热力学模型。通过提出的模型,热负荷,推导并讨论了各种结构的性能系数(COP)及其之间的最佳关系。对不同结构的性能进行了数值评估。更重要的是,根据获得的结果,通过引入测量与系统可逆极限的偏差的参数,可以生成并比较不同结构在最大热负荷下的COP的上限和下限。因此,在低耗散假设的框架内确定了低耗散三端热泵和热变压器的最佳结构,分别。获得了与以前的研究和工程实践相一致的各种三端设备的最佳结构,这证实了低耗散模型和内可逆模型之间的兼容性,强调了低耗散模型在多端热力设备中应用的有效性。提出的模型和获得的重要结果丰富了热驱动热泵系统的理论热力学模型,并可能为现实的热驱动热泵系统的设计和运行提供一些有用的指导。
    Thermally driven heat pump systems play important roles in the utilization of low-grade thermal energy. In order to evaluate and compare the performances of three different constructions of thermally driven heat pump and heat transformer, the low-dissipation assumption has been adopted to establish the irreversible thermodynamic models of them in the present paper. By means of the proposed models, the heating loads, the coefficients of performance (COPs) and the optimal relations between them for various constructions are derived and discussed. The performances of different constructions are numerically assessed. More importantly, according to the results obtained, the upper and lower bounds of the COP at maximum heating load for different constructions are generated and compared by the introduction of a parameter measuring the deviation from the reversible limit of the system. Accordingly, the optimal constructions for the low-dissipation three-terminal heat pump and heat transformer are determined within the frame of low-dissipation assumption, respectively. The optimal constructions in accord with previous research and engineering practices for various three-terminal devices are obtained, which confirms the compatibility between the low-dissipation model and endoreversible model and highlights the validity of the application of low-dissipation model for multi-terminal thermodynamic devices. The proposed models and the significant results obtained enrich the theoretical thermodynamic model of thermally driven heat pump systems and may provide some useful guidelines for the design and operation of realistic thermally driven heat pump systems.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

       PDF(Pubmed)

  • 文章类型: Journal Article
    There are two main categories of dryness monitoring indices based on spectral feature space. One category uses the vertical distance from any point to a line passing through the coordinate origin, which is perpendicular to a soil line, to monitor the dryness conditions. The most popular indices are the Perpendicular Dryness Index (PDI) and the modified perpendicular dryness index (MPDI). The other category uses the distance from any point in feature space to the coordinate origin to represent the dryness status, for instance, the soil moisture (SM) monitoring index (SMMI) and the modified soil moisture monitoring index (MSMMI). In this study, the performances and differences of these four indicators were evaluated using field-measured SM (FSM) data based on Gaofen-1 (GF-1) wide field of view (WFV), Landsat-8 Operational Land Imager (OLI), and Sentinel-2 Multi-Spectral Instrument (MSI) sensors. Performance evaluations were conducted in two study areas, namely an arid and semi-arid region of northwest China and a humid agricultural region of southwest Canada. We employed gradient-based structural similarity (GSSIM) to quantitatively assess the similarity of the structural information and structural characteristics among these four indicators. Monitoring SM in bare soil or low vegetation-covered areas in the semi-arid region, the SMMI, PDI, MSMMI, and MPDI from Near-Infrared (NIR)-Red had significantly negative linear correlations with the FSM at 0-5-cm depth (P < 0.01). However, SMMI was better than PDI in estimating SM in bare soil, which was better than MSMMI and MPDI for GF-1. Moreover, the PDI and SMMI had similar SM evaluation abilities, which were better than those of MPDI and MSMMI for Landsat-8. The GSSIM map of the SMMI/PDI and the MSMMI/MPDI showed that the low change areas accounted for 99.89% and 98.89% for GF-1, respectively, and 95.78% and 94.45% for Landsat-8, respectively. This result indicated that the SMMI, PDI, MSMMI, and MPDI values from NIR-Red in low vegetation cover were similar. In monitoring SM in agricultural vegetation areas, the accuracy of the four indices from Short-Wave Infrared (SWIR) feature space was higher than that from NIR-Red feature space for Sentinel-2. The SM monitoring effect of MSMMI and MPDI was better than that of SMMI and PDI. Due to the lack of SWIR band, GF-1 was limited in monitoring SM in vegetation-covered areas. The SMMI and MSMMI, which do not rely on the soil line, were more suitable than PDI and MPDI for retrieving SM in the complex surface environment depending on the soil line and the number of parameters. GF-1 with 16-m resolution had higher accuracy in SM assessment than Landsat-8 with 30-m resolution and had almost the same accuracy as Sentinel-2 with 20 m.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    The removal of arsenic from groundwater is an important issue for environmental safety and human health. Research focused on the comparative assessment of arsenic removal from arsenic-bearing groundwater and arsenic-containing-synthetic water (2 mg/L) using natural magnetic material (NMM) (rock) and synthesized magnetic material (SMM) by Bacillus pasteurii and humic acid. The arsenic-bearing groundwater (97.56 ± 0.05 μg/L) exceed the WHO limit (10 μg/L) of arsenic concentration for drinking water. The NMM contains dominantly magnetite, hematite, ferrihydrate, coesite, quartz, and stishovite. The NMM of natural rock exhibited the existence of iron (6.25-8.86% Fe3O4), which is widespread and important component in sedimentary rocks. The investigation on vibrating sample magnetometers (VSM) of NMM and SMM demonstrated the typical magnetization properties, which can be separated after arsenic removal process. The thermogravimetric analysis (TGA) of SMM displayed the existence of organic matter decomposition during particle synthesis. The TEM and SEM exhibited the nanoparticle particle formation within the range of 10-39 nm (10-20 nm particle Fe3O4 through B. pasteurii). FTIR spectrum (before and after removal of arsenic) indicated the existence and binding nature in between arsenic and iron. >90% of arsenic was removed from arsenic-bearing groundwater using Fe3O4, Fe3O4 (N2-Environment), Fe3O4 with humic acid, and Fe3O4 with B. pasteurii after 25 min, 8 min, 13 min and 120 min, respectively. In case of NMM in Site-A, the arsenic removal was observed very fast as 85-87% within 30 s, whereas 95-99%, 93-95% and 88-91% removal detected using the sample of Site-A, Site-B, and Site-C respectively, after 120 min at natural pH (8.31 ± 0.05) of arsenic-bearing groundwater. Thus, NMM, (ecofriendly green material), can be applicable for arsenic removal from arsenic-bearing groundwater.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

公众号