Climate variables

气候变量
  • 文章类型: Journal Article
    Awassi是一个肥尾羊品种,叙利亚最好的品种是著名的。Awassi绵羊是叙利亚红肉和牛奶生产的主要来源。在这项研究中,我们使用1961年至2020年的时间序列数据估算了各种因素对绵羊肉和牛奶产量的影响。本研究采用柯布-道格拉斯生产函数对数据进行分析。获得的结果表明,叙利亚的Awassi肉类生产受到car体重量(p<0.001)和屠宰绵羊数量(p<0.001)的积极和显着影响,弹性系数分别为0.994和1.000。模型结果表明,在0.1%的显著性水平下,原奶产量和产奶动物对产奶量有积极和显著的影响。弹性系数为0.998。然而,气候因素(降水和温度)对1%和5%显著水平的牛奶产量有显著影响和负面影响,分别。这一结果阐明了政府应实施的政策和程序,以发展叙利亚的绵羊生产。因此,可以说,政策制定者应该通过实施育种计划来提高绵羊的质量和生产力特征,提高放牧潜力,保护天然牧场。此外,应支持饲料配给,以帮助育种者克服干旱和高饲料价格的影响。
    Awassi is a fat-tailed sheep breed, and the best breed in Syria is famous. Awassi sheep are Syria\'s main source of red meat and milk production. In this study, we estimated the influence of various factors on sheep meat and milk production using time-series data from 1961 to 2020. This study employed the Cobb-Douglas production function to analyze the data. The results obtained indicate that Awassi meat production in Syria was positively and significantly influenced by carcass weight (p < 0.001) and quantity of slaughtered sheep (p < 0.001), with elasticity coefficients of 0.994 and 1.000, respectively. The model results show that raw milk yield and milk animals have a positive and significant influence on milk production at the 0.1 % significance level, with an elasticity coefficient of 0.998. However, climatic factors (precipitation and temperature) have a significant effect and negative influence on milk production at the 1 % and 5 % significance levels, respectively. This result sheds light on the policies and procedures the government should implement to develop sheep production in Syria. Therefore, it can be stated that policymakers should enhance the quality and productivity characterization of sheep through the implementation of breeding programs, improve grazing potential, and protect natural pastures. Furthermore, feed rations should be supported to help breeders overcome the effects of drought and high feed prices.
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  • 文章类型: Journal Article
    热带森林是全球生物多样性的热点地区,在全球碳(C)循环中至关重要。了解异质和生物多样性系统中地上碳储量(AGC)的驱动因素可以阐明生物多样性与碳积累之间关系的基础过程。这里,我们调查生物多样性,环境,景观结构影响AGC。我们在349个地块中检查了此类关联,这些地块包括巴西南部大西洋森林95,346平方公里,包括三种森林类型:密集的全层森林(DF),混合全层森林(MF),和季节性落叶林(SF)。每个地块都由环境变量描述,景观指标,和生物多样性(物种丰富度和功能多样性)。我们利用多样性,环境,和景观变量来建立广义线性混合模型,并了解哪些会影响森林AGC。我们发现,在所有森林类型中,物种丰富度与AGC呈正相关,合并和单独。季节性温度和等温线会影响所有森林类型的AGC;此外,股票受到SF年降水量和MF等温线的积极影响。在景观指标中,总碎片边缘对MF中的碳储量产生负面影响。我们的结果表明,物种多样性对亚热带森林碳储量的重要性。气候效应也是相关的,显示这些因素的重要性,尤其是在一个气候变化往往会对森林蓄积量产生负面影响的世界里。
    Tropical forests are global biodiversity hotspots and are crucial in the global carbon (C) cycle. Understanding the drivers of aboveground carbon stock (AGC) in a heterogeneous and biodiverse system can shed light on the processes underlying the relationship between biodiversity and carbon accumulation. Here, we investigate how biodiversity, environment, and landscape structure affect AGC. We examined such associations in 349 plots comprising over 95,346 km2 the Atlantic Forest of southern Brazil, encompassing three forest types: Dense Ombrophylous Forest (DF), Mixed Ombrophylous Forest (MF), and Seasonal Deciduous Forest (SF). Each plot was described by environmental variables, landscape metrics, and biodiversity (species richness and functional diversity). We used diversity, environmental, and landscape variables to build generalized linear mixed models and understand which can affect the forest AGC. We found that species richness is associated positively with AGC in all forest types, combined and separately. Seasonal temperature and isothermality affect AGC in all forest types; additionally, stocks are positively influenced by annual precipitation in SF and isothermality in MF. Among landscape metrics, total fragment edge negatively affects carbon stocks in MF. Our results show the importance of species diversity for carbon stocks in subtropical forests. The climate effect was also relevant, showing the importance of these factors, especially in a world where climate change tends to affect forest stock capacity negatively.
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  • 文章类型: Journal Article
    汞(Hg)是一种有毒金属,对生态系统构成重大风险,生物群,人类健康,并且仍然是优先关注的问题。在温带和北方湖泊中,汞和甲基汞(MMHg)预计会随着大气汞沉积而变化,湖水化学,流域特征和气候变量。这项研究的目的是量化未扰动的贫营养湖泊中的Hg和MMHg,并确定控制其分布的因素。我们首先假设湖泊Hg(和MMHg在较小程度上)的空间变化与大气沉积有关,流域特征,和陆地出口溶解有机碳(DOC)。我们其次研究了1990年代中期至2010年代末之间观察到的大气汞排放减少后,湖泊汞浓度是否有所下降。我们发现总的来说,大气汞对湖泊汞和MMHg浓度影响不大,两者都主要受到源自森林流域的DOC输入的影响。DOC和Hg之间的关系在春季和秋季之间有所不同,春季Hg与DOC的比率是春季的两倍。这似乎与汞的融雪输入(DOC的输入相对减少)或在冰雪覆盖期间汞的内部湖泊积累有关。在20年来密集访问的10个湖泊中,尽管大气汞浓度呈显著负趋势,但只有3个显示湖泊汞显著下降,表明大气和地表水时间趋势之间存在滞后。总的来说,陆地集水区保留了约80%的大气汞,这意味着在过去的几十年中,土壤中已经建立了大型汞池。因此,仅减少大气中的汞并不一定会导致湖泊中的汞减少,因为汞的浓度可能会受到DOC出口趋势和流域特征的调节。这强调需要提高我们对汞从集水区转移到湖泊的过程的理解。
    Mercury (Hg) is a toxic metal that presents a major risk to ecosystems, biota, human health, and remains a priority concern. In temperate and boreal lakes Hg and methylmercury (MMHg) are expected to vary as a function of atmospheric Hg deposition, lake water chemistry, catchment characteristics and climate variables. The aim of this study was to quantify Hg and MMHg in unperturbed oligotrophic lakes and to identify the factors controlling their distribution. We first hypothesized that lake Hg (and MMHg to lesser extent) spatial variations are linked to atmospheric deposition, catchment characteristics, and terrestrial exportation of dissolved organic carbon (DOC). We secondly examined if lake Hg concentrations have followed the decrease in atmospheric Hg emission observed between the mid-1990s to the end-2010s. We found that overall, atmospheric Hg has little impact on lake Hg and MMHg concentrations, which are both primarily influenced by DOC input originating from the forest catchment. The relationship between DOC and Hg differed between the spring and the fall, with a Hg-to-DOC ratio twice as high in spring. This seems related to snowmelt input of Hg (with a relatively reduced input of DOC) or the internal lake build-up of Hg during the ice-covered period. Of the 10 lakes intensively visited over a 20-year period, only 3 showed significant lake Hg decreases despite significant negative trends in atmospheric Hg concentrations, suggesting a lag between atmospheric and surface water temporal trends. Overall, terrestrial catchments retain around 80% of atmospheric Hg implying that large Hg pools have been built up in soils in the last decades. As such, the reduction of atmospheric Hg alone will not necessarily result in Hg decreases in lakes, since the Hg concentrations may be modulated by DOC export trends and catchment characteristics. This stresses the need to improve our understanding of the processes governing Hg transfers from catchments into lakes.
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  • 文章类型: Journal Article
    这项研究旨在调查影响印度不同气候分地区近地表臭氧(850hpa)浓度的季节性和长期(2003-2021年)变化的因素。ERA-5和CAAQMS(连续环境空气质量监测站)地面测量的每日(2019-2021年)近地表臭氧值的详细比较表明,ERA-5与CAAQMS测量在时间上同相,与印度的气候分区域无关。ERA-5近地表臭氧在大多数气候分区域显示出统计上显著的长期(2003-2021年)积极趋势[每十年2%-4%(ppd)],在印度-恒河飞机(IGP)上,印度南部和中部的趋势尤其强劲。还分别估计了每个季节的趋势,在秋季和冬季,印度中部和南部的大部分为正(2-6ppd)。广泛的气候分析表明,印度季风系统中的风逆转在整个印度次大陆的这种趋势模式中起着至关重要的作用。6月至9月的西南风可能会带来海洋来源的臭氧不足空气,因此引起稀释效应,而秋末和冬季初的东北风似乎从平流层-对流层流出物中吸收了富含臭氧的空气。它允许印度中部和南部的近地表臭氧增强。季节性主成分分析(PCA)表明,前体气体(CH4和NO2)和气候变量,尤其是比湿度(SH)是冬季近地表臭氧变化的主要驱动因素,在春天,气候变量,如边界层高度(BLH),温度(T)和SH有显著作用。主成分回归(PCR)显示,近地表臭氧水平长期增加,主要由IGP和南部次区域的前体浓度主导。然而,BLH,T和SH可以显着解释印度东北部和沿海的近地表臭氧趋势。
    This study aims to investigate the factors influencing seasonal and long-term (2003-2021) changes in the near surface ozone (850 hpa) concentrations over different climatic sub-regions of India. Detailed comparison of daily (2019-2021) near surface ozone values of ERA-5 and CAAQMS (Continuous Ambient Air Quality Monitoring Stations) ground-based measurements revealed that ERA-5 is temporally in phase with CAAQMS measurements falling indifferent climatic sub-regions of India. ERA-5 near surface ozone shows statistically significant long-term (2003-2021) positive trends [2-4 percent per decade (ppd)] over most of the climatic sub-regions, over Indo-Gangetic Planes (IGPs), Southern and Central India trends are particularly strong. Trends were also estimated for each season separately, which were largely positive (2-6 ppd) over Central and Southern India in the Autumn and Winter seasons. Extensive climatological analysis reveals that the reversal of winds in the Indian monsoonal system plays a vital role in such trend patterns across the Indian subcontinent. South-westerly winds from June through September presumably bring ozone deficit air of marine origin, thus causing a dilution effect while the North-easterly winds during late Autumn and early Winters plausibly bring ozone-rich air from the stratospheric-tropospheric efflux dominated Himalayan region. It allows near surface ozone enhancement over Central and Southern India. Seasonal Principal component analysis (PCA) revealed that precursor gases (CH4 and NO2) and climatic variables especially specific humidity (SH) are the primary drivers of near surface ozone variability in the Winter season, while in Spring, climatic variables like boundary layer height (BLH), temperature (T) and SH have a significant role. Principal component regression (PCR) reveals a long-term increase in near surface ozone levels mostly dominated by precursor concentration over IGPs and Southern sub-regions. Whereas, BLH, T and SH significantly explain near surface ozone trends over North-eastern and Coastal India.
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  • 文章类型: Journal Article
    冰川面积的变化,冰川湖,碎片盖,和地貌特征如碎片扇对冰川动力学有重大影响。因此,精确及时地观察和跟踪冰川面的变化是必要的。高空间分辨率遥感图像的可用性使在当地分析冰川表面变化变得可行。然而,随着空间分辨率的提高,光谱变异性增加,在变化检测过程中引发了其他挑战(例如错误的更改和错误注册)。可以优选地使用基于对象的变化检测(OBCD)方法而不是常规的基于像素的变化检测方法来处理这些挑战。因此,这项研究提出了一种使用高空间分辨率遥感图像来检测冰川特征变化的OBCD方法。通过将冰川特征与重要的气候变量相关联,进一步分析了冰川特征的变异性,也就是说,气温和降水。作为一个案例研究,已使用高空间分辨率WorldView-2和线性成像自扫描系统(LISS)-4图像研究了Gangotri冰川(印度北阿坎德喜马拉雅山)特征的变化,为期3年2011-2014年。冰川表面和非冰川表面之间的光谱对应关系已通过将亮度温度和斜率视为辅助数据来临时区分来处理。使用OBCD方法已获得〜84%的变化检测精度。结果进一步表明,冰川特征的变化与气候观测一致。
    Changes in glacier area, glacial lakes, debris cover, and geomorphological features such as debris fans have a significant impact on glacial dynamics. Therefore, precise and timely observation and tracking of glacier surface changes is a necessity. The availability of high spatial resolution remote sensing images has made it viable to analyse the glacier surface changes at a local level. However, with an increase in spatial resolution, the spectral variability increases, giving rise to additional challenges (such as false changes and misregistration) in the change detection process. These challenges can preferably be dealt with using an object-based change detection (OBCD) approach rather than the conventional pixel-based change detection approach. Therefore, this study has proposed an OBCD methodology using high-spatial-resolution remote sensing images to detect changes in glacier features. Variability in glacier features has been further analysed by associating it with important climate variables, that is, air temperature and precipitation. As a case study, the changes in Gangotri Glacier (Uttarakhand Himalayas in India) features have been studied using high-spatial-resolution WorldView-2 and Linear Imaging Self-Scanning System (LISS)-4 images for a 3-year period 2011-2014. The spectral correspondences between glacier surface and non-glacier surface have been handled by considering brightness temperature and slope as ancillary data to improvise their distinction. A change detection accuracy of ~ 84% has been obtained using the OBCD approach. Results further show that the variations in glacier features are in congruence with the climatic observations.
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  • 文章类型: Journal Article
    登革热是世界上传播最迅速的蚊媒病毒性疾病之一。因为它主要在城市和半城市地区发现,城市化和影响环境和幼虫栖息地的相关人类活动可能成为风险因素(例如,车道宽度,街道沟渠的条件),以传播登革热。然而,目前还没有关于登革热流行的基于微观尺度城市化的危险因素的系统研究。我们描述了研究区域,与城市化相关的两个微观尺度环境风险因素,和气象数据。由于观测涉及空间和时间相关性,我们还使用一些统计方法来分析城市化与登革热之间的关系。在这项研究中,我们分析了高雄的数据,台湾南部人口稠密的城市,并发现与城市化相关的环境风险因素(蚊子幼虫的沟渠和密密麻麻的街道被称为“登革热车道”)和登革热病例的聚集效应之间存在正相关。统计分析还显示,研究区域内阳性沟渠的发生与登革热泳道的发生显着相关。本文还分析了气候变量与正沟之间的关系,表明登革热与降雨和温度之间的关系,温度有更大的影响。总的来说,这项工作对政府决策者来说是直接相关和适用的,他们将需要减少这些有利的栖息地,为病媒传播疾病的传播者,并实施新的城市建设法规,从而减少登革热在未来爆发中的传播。
    Dengue is one of the world\'s most rapidly spreading mosquito-borne viral diseases. As it is found mostly in urban and semi-urban areas, urbanization and associated human activities that affect the environment and larval habitats could become risk factors (e.g., lane width, conditions of street ditches) for the spread of dengue. However, there are currently no systematic studies of micro-scale urbanization-based risk factors for the spread of dengue epidemics. We describe the study area, two micro-scale environmental risk factors associated with urbanization, and meteorological data. Since the observations involve spatial and temporal correlations, we also use some statistical methods for the analysis of spatial and spatial-temporal data for the relationship between urbanization and dengue. In this study, we analyzed data from Kaohsiung, a densely populated city in southern Taiwan, and found a positive correlation between environmental risk factors associated with urbanization (ditches positive for mosquito larvae and closely packed streets termed \"dengue lanes\") and clustering effects in dengue cases. The statistical analysis also revealed that the occurrence of positive ditches was significantly associated with that of dengue lanes in the study area. The relationship between climate variables and positive ditches was also analyzed in this paper, indicating a relationship between dengue and both rainfall and temperature, with temperature having a greater effect. Overall, this work is immediately relevant and applicable for policymakers in government, who will need to reduce these favorable habitats for vector-born disease spreaders and implement regulations for new urban constructions to thus reduce dengue spread in future outbreaks.
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  • 文章类型: Journal Article
    生物或化学化合物的空中颗粒物(PM)的长距离传播和运输,它们被认为是SARS-CoV-2病毒体的可能携带者,可能对COVID-19病毒性疾病的发病率和严重程度产生负面影响。考虑到550nm处的总气溶胶光学深度(AOD)作为大气气溶胶负荷变量,在2020年2月26日至2022年3月31日期间,直径≤2.5µm(PM2.5)的可吸入细PM或直径≤10µm(PM10)的粗PM,以及COVID-19在罗马尼亚的五次浪潮,本研究调查了室外PM对布加勒斯特市COVID-19大流行的影响。通过对PM2.5、PM10和气候参数的每日平均时间序列和卫星数据进行描述性统计分析,这项研究发现PM2.5和PM10浓度下降趋势为24.58%和18.9%,分别与大流行前时期(2015-2019年)相比。高浓度PM2.5和PM10颗粒暴露与COVID-19发病率和死亡率呈正相关。整个大流行期间得出的平均PM2.5/PM10比率相对较低(<0.44),表明与交通相关的粗颗粒分数占主导地位。在第一波和第三波COVID-19大流行及其相关的封锁期间,布加勒斯特地区的平均AOD水平显着下降(~28.2%和~16.4%,分别)与大流行前(2015-2019年)平均AOD水平相比。这项研究的结果对于在病毒感染期间实施COVID-19安全控制和健康措施的决策者非常重要。
    The long-distance spreading and transport of airborne particulate matter (PM) of biogenic or chemical compounds, which are thought to be possible carriers of SARS-CoV-2 virions, can have a negative impact on the incidence and severity of COVID-19 viral disease. Considering the total Aerosol Optical Depth at 550 nm (AOD) as an atmospheric aerosol loading variable, inhalable fine PM with a diameter ≤2.5 µm (PM2.5) or coarse PM with a diameter ≤10 µm (PM10) during 26 February 2020-31 March 2022, and COVID-19\'s five waves in Romania, the current study investigates the impact of outdoor PM on the COVID-19 pandemic in Bucharest city. Through descriptive statistics analysis applied to average daily time series in situ and satellite data of PM2.5, PM10, and climate parameters, this study found decreased trends of PM2.5 and PM10 concentrations of 24.58% and 18.9%, respectively compared to the pre-pandemic period (2015-2019). Exposure to high levels of PM2.5 and PM10 particles was positively correlated with COVID-19 incidence and mortality. The derived average PM2.5/PM10 ratios during the entire pandemic period are relatively low (<0.44), indicating a dominance of coarse traffic-related particles\' fraction. Significant reductions of the averaged AOD levels over Bucharest were recorded during the first and third waves of COVID-19 pandemic and their associated lockdowns (~28.2% and ~16.4%, respectively) compared to pre-pandemic period (2015-2019) average AOD levels. The findings of this research are important for decision-makers implementing COVID-19 safety controls and health measures during viral infections.
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  • 文章类型: Journal Article
    气候因素的影响(温度,湿度,湿度降水,和霜冻日)对人口的变化,损坏,和豹蛾的侵扰区,ZeuzerapyrinaL.,在2006-2018年期间在伊朗的四个地区进行了研究,包括萨曼,阿拉克,Najaf-abad,还有Baft.对于趋势分析,Mann-Kendall检验是对气候和害虫种群的时间序列数据进行的。根据结果,年平均值(肯德尔的统计数据,T=0.64和0.48),年最小值(T=0.60和0.42),和1月的平均值(分别为T=0.64和0.61)温度在Saman和Najaf-abad显示出增加的趋势。此外,阿拉克的年平均最低温度和1月温度(分别为T=0.41和0.45)和巴夫特的年平均最高温度(T=0.79)呈上升趋势。霜冻天数/年(肯德尔的统计数据,T=-0.63,-0.53,-0.32和-0.37)和年平均相对湿度(分别为T=-0.43,-0.63,-0.64和-0.42)在萨曼,阿拉克,木筏,和纳杰夫-巴德站。趋势分析表明,捕获的蛾的平均数量显着增加(T=0.59,0.76和0.90),受感染的树枝/树的百分比(T=0.66,0.58和0.90),Saman的活动孔/树的数量(T=0.79、0.55和0.68)和受感染区域(分别为T=0.99、0.73和0.98),阿拉克和纳杰夫-巴德站。根据逐步回归,一月份的平均气温,秋天,和冬季是增加Z.Pyrina伤害和种群的最有效变量,而相对湿度和霜冻天数对减少它起了主要作用。
    The effect of climate factors (temperature, humidity, precipitation, and frost days) on the population changes, damage, and infestation area of the leopard moth, Zeuzera pyrina L., was studied during 2006-2018 in four parts of Iran including Saman, Arak, Najaf-abad, and Baft. For trend analysis, the Mann-Kendall test was run on time series data of both climate and pest population. According to the results, the annual mean (Kendall\'s statistics, T = 0.64 and 0.48), annual minimum (T = 0.60 and 0.42), and January mean (T = 0.64 and 0.61, respectively) temperatures showed increasing trends in Saman and Najaf-abad. Moreover, the annual mean minimum and January temperatures (T = 0.41 and 0.45, respectively) in Arak and the annual mean maximum temperature (T = 0.79) in Baft showed increasing trends. The number of frost days/year (Kendall\'s statistics, T = -0.63, -0.53, -0.32 and -0.37) and annual mean relative humidity (T = -0.43, -0.63, -0.64 and -0.42, respectively) showed decreasing trends in Saman, Arak, Baft, and Najaf-abad stations. Trend analysis indicated significant increases in the mean number of moths caught (T = 0.59, 0.76 and 0.90), the percentage of infested branches/tree (T = 0.66, 0.58, and 0.90), the number of active holes/tree (T = 0.79, 0.55, and 0.68) and the infested areas (T = 0.99, 0.73, and 0.98, respectively) in Saman, Arak and Najaf-abad stations. According to stepwise regression, the mean temperatures of January, autumn, and winter were the most effective variables for increasing Z. pyrina damage and population, while relative humidity and the number of frost days played the major role in reducing it.
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  • 文章类型: Journal Article
    预计全球一半以上的人口生活在容易感染登革热的地区,其中绝大多数在亚洲。登革热是公众健康关注的问题,特别是在泰国南部地区,由于有利于其传播的环境因素。登革热感染的风险在人群水平上在时间和空间上有所不同,因此,考虑时空变化,研究感染风险非常重要。
    本研究使用R软件的CARBayesST软件包,使用马尔可夫链蒙特卡罗(MCMC)模拟,在贝叶斯环境中提出了联合时空流行病学模型。为此,使用了泰国公共卫生部提供的2002年至2018年泰国南部地区的每月登革热记录和8个环境变量.
    结果表明,随着温度的升高,阴雨天数和海平面压力与登革热的发病率较高,因此发病率较高,而风速的增加似乎暗示了一个保护因素。同样,我们发现,在不久的将来,登革热的风险在Phipun地区升高,PhromKili,LanSaka,PhraPhrom和ChaloemPhakiat。由此产生的估计提供了对协变量风险因素影响的见解,泰国南部地区的时空趋势和与登革热相关的健康不平等。
    考虑到一些可能抑制或增强登革热发生的人为因素,讨论了可能的含义。风险图表明哪些地区高于和低于基线风险,允许识别局部异常和高风险边界。在不久的将来,考虑到东南亚蚊子传播的潜在因素,需要预防和控制疾病风险升高的威胁。
    More than half of the global population is predicted to be living in areas susceptible to dengue transmission with the vast majority in Asia. Dengue fever is of public health concern, particularly in the southern region of Thailand due to favourable environmental factors for its spread. The risk of dengue infection at the population level varies in time and space among sub-populations thus, it is important to study the risk of infection considering spatio-temporal variation.
    This study presents a joint spatio-temporal epidemiological model in a Bayesian setting using Markov chain Monte Carlo (MCMC) simulation with the CARBayesST package of R software. For this purpose, monthly dengue records by district from 2002 to 2018 from the southern region of Thailand provided by the Ministry of Public Health of Thailand and eight environmental variables were used.
    Results show that an increasing level of temperature, number of rainy days and sea level pressure are associated with a higher occurrence of dengue fever and consequently higher incidence risk, while an increasing level of wind speed seems to suggest a protective factor. Likewise, we found that the elevated risks of dengue in the immediate future are in the districts of Phipun, Phrom Kili, Lan Saka, Phra Phrom and Chaloem Phakiat. The resulting estimates provide insights into the effects of covariate risk factors, spatio-temporal trends and dengue-related health inequalities at the district level in southern Thailand.
    Possible implications are discussed considering some anthropogenic factors that could inhibit or enhance dengue occurrence. Risk maps indicated which districts are above and below baseline risk, allowing for the identification of local anomalies and high-risk boundaries. In the event of near future, the threat of elevated disease risk needs to be prevented and controlled considering the factors underlying the spread of mosquitoes in the Southeast Asian region.
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  • 文章类型: Journal Article
    背景:连续叶子出现之间的时间,或者phyllochron,表征一年生植物的营养发育。假设检验模型,可以比较遗传群体和/或环境条件之间的叶时,通常基于热时间对叶片数量的回归;大多数情况下,假定叶片出现率恒定。然而,回归模型忽略了叶数过程的自相关,并可能导致有偏差的测试程序。此外,恒定叶片出现率的假设可能过于严格。
    方法:我们提出了一个随机过程模型,其中新叶的出现被认为是由连续的时间事件引起的。该模型提供了灵活且更准确的建模以及无偏的测试程序。将其应用于三年来在田间收集的原始玉米数据集,这些数据来自两个玉米自交系的开花时间的两个不同选择实验。
    结论:我们表明,在选择群体之间没有观察到叶型的主要差异,而是在祖先系之间。多年的实验和叶子排名。我们的结果突显了与一个季节恒定的叶子出现率的假设的强烈背离,这可能与气候变化有关。即使无法明确确定单个气候变量的影响。
    BACKGROUND: The time between the appearance of successive leaves, or phyllochron, characterizes the vegetative development of annual plants. Hypothesis testing models, which allow the comparison of phyllochrons between genetic groups and/or environmental conditions, are usually based on regression of thermal time on the number of leaves; most of the time a constant leaf appearance rate is assumed. However regression models ignore auto-correlation of the leaf number process and may lead to biased testing procedures. Moreover, the hypothesis of constant leaf appearance rate may be too restrictive.
    METHODS: We propose a stochastic process model in which emergence of new leaves is considered to result from successive time-to-events. This model provides a flexible and more accurate modeling as well as unbiased testing procedures. It was applied to an original maize dataset collected in the field over three years on plants originating from two divergent selection experiments for flowering time in two maize inbred lines.
    CONCLUSIONS: We showed that the main differences in phyllochron were not observed between selection populations but rather between ancestral lines, years of experimentation and leaf ranks. Our results highlight a strong departure from the assumption of a constant leaf appearance rate over a season which could be related to climate variations, even if the impact of individual climate variables could not be clearly determined.
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