Impact Of Seasonal Variation Research Articles

Effects of Treated Manure Conditions on Ammonia and Hydrogen Sulfide Emissions from a Swine Finishing Barn Equipped with Semicontinuous Pit Recharge System in Summer

Gaseous emissions from animal production systems affect the local and regional air quality. Proven farm-scale mitigation technologies are needed to lower these emissions and to provide management practices that are feasible and sustainable. In this research, we evaluate the performance of a unique approach that simultaneously mitigates emissions and improves air quality inside a barn equipped with a manure pit recharge system. Specifically, we tested the effects of summertime feeding rations (used by farmers to cope with animal heat stress) and manure management. To date, the pit recharge system has been proven to be effective in mitigating both ammonia (NH3; approximately 53%) and hydrogen sulfide (H2S; approximately 84%) emissions during mild climate conditions. However, its performance during the hot season with a high crude protein diet and high nitrogen loading into the pit manure recharge system is unknown. Therefore, we compared the emissions and indoor air quality of the rooms (240 pigs, ~80 kg each) equipped with a conventional slurry and pit recharge system. The main findings highlight the importance and impact of seasonal variation and diet and manure management practices. We observed 31% greater NH3 emissions from the pit recharge system (33.7 ± 1.4 g·head−1·day−1) compared with a conventional slurry system (25.9 ± 2.4 g·head−1·day−1). Additionally, the NH3 concentration inside the barn was higher (by 24%) in the pit recharge system compared with the control. On the other hand, H2S emissions were 55% lower in the pit recharge system (628 ± 47 mg·head−1·day−1) compared with a conventional slurry pit (1400 ± 132 mg·head−1·day−1). Additionally, the H2S concentration inside the barn was lower (by 54%) in the pit recharge system compared with the control. The characteristics of the pit recharge liquid (i.e., aerobically treated manure), such as the total nitrogen (TN) and ammonium N (NH4-N) contents, contributed to the higher NH3 emissions from the pit recharge system in summer. However, their influence on H2S emissions had a relatively low impact, i.e., emissions were still reduced, similarly as they were in mild climate conditions. Overall, it is necessary to consider a seasonal diet and manure management practices when evaluating emissions and indoor air quality. Further research on minimizing the seasonal nitrogen loading and optimizing pit recharge manure characteristics is warranted.

Impact of seasonal variations on soil electrical conductivity as an earthquake precursor along the Margalla Fault Line, Islamabad

The present research deals with the study of soil electrical conductivity as an earthquake precursor along the Margalla fault line and its correlation with the increase in temperature due to global warming. Moreover, comparative study to analyze correlation of EC with physico chemical properties of soil like moisture content, pH, temperature and texture has been conducted. This correlation can help in short term probabilistic analysis of earthquakes with accuracy and without bias because many inter related properties have also been taken into account. Thus, analyses were conducted by collecting soil samples through incremental sampling technique and analyzing by laboratory methods including electrical meters for pH and EC and hydrometer for soil texture analysis. Results suggest that EC and temperature have a negative correlation which means that increase in temperature results in decline in soil EC along the studied fault line. Also, low temperature can increase the EC of soil, which can assist in developing a probabilistic seismic hazard analysis in the area in context of the electrical conductivity as a short term precursor to earthquakes.

Assessment of aflatoxin in milk and feed samples and impact of seasonal variations in the Punjab, Pakistan.

The present study was designed to assess the incidence of aflatoxin contamination in animal feed and raw milk samples (total 240 each) collected from dairy farms during the complete year of 2015. These samples were collected through a cluster random sampling technique by dividing the province of Punjab, Pakistan into five clusters (north, south, east, west and central). Factors (environmental & physical) affecting aflatoxin contamination in milk and animal feed at farms were also studied. The AFM1 levels in raw milk & AFB1 levels in feed samples were analyzed by using the ELISA technique. Results demonstrated that overall about 53% raw milk samples from dairy farms were contaminated beyond the US MRL (0.50 µg/L) for AFM1 with than average level of 0.59 µg/L, while the 95% farm feed samples were exceeding the FDA MRL (20 µg/kg) of AFB1 with average level of 43 µg/kg. During winter season, the concentration of AFM1 was higher in all clusters with avg 0.68 µg/L, while the AFB1 contamination was highest in the spring season with avg 54 µg/kg. Market feed prices had negative correlation with AFB1 contamilevels, which were further supported by the positive correlation between quantity of feed at farms with AFM1 and AFB1 contamination. Results exhibited significantly positive impact of environmental factors on milk and feed aflatoxin contamination levels, whereas temperature showed an inverse relationship with AFM1 and AFB1 levels. The study recommends need of synergistic extension work to support dairy farms and highlight the contamination levels for regulatory bodies to introduce strategic policies for control measures.

Impact of seasonal variations of ambient seismic noise level on the number of registered earthquakes in the Arctic regions

Researchers at the Seismological Laboratory of the Institute of Geodynamics and Geology of the Federal Center for Integrated Arctic Research of the Russian Academy of Sciences (FCIARctic) have been engaged in the seismological monitoring of the European Arctic sector since 2011. In this paper, we present a comparative assessment of the earthquakes spatial distribution in this region based on the data from the International Seismological Centre (ISC) and the FCIARctic’s Arkhangelsk Seismic Network (ASN) obtained in 2012–2016. The paper presents the waveforms of earthquakes occurred at the Gakkel Ridge and the Svalbard archipelago processed with the use of a Russian software package WSG (Windows Seismic Grafer) recommended by the Unified Geophysical Service of the Russian Academy of Sciences. A standard 4–8 Hz bandpass filter was used for the processing of regional Arctic earthquakes. The impact of seasonal variations on the quality of earthquakes registration was analysed based on the seismograms recorded by the ASN’s island-based Arctic stations from 2012 to 2014 The same analysis was done for the central broadband sensor SPA0 of the Norwegian NORSAR-owned SPITS group installed at the Svalbard archipelago. A correlation has been established between the number of earthquakes recorded by the ASN’s island Arctic stations and SPA0 station. The number of regional earthquakes, recorded by ASN’s island Arctic stations is is smaller in summer-autumn periods than in winter periods. Forthe SPA0 station, which is part of SPITS group, there is not seasonality in the number of registered earthquakes. Generally, earthquakes are recorded uniformly, exception on January. This might be due to the increased seismic activity in the Svalbard archipelago during that period.

Point and Interval Predictions for Tanjiahe Landslide Displacement in the Three Gorges Reservoir Area, China

Accurate landslide displacement prediction has great practical significance for mitigating geohazards. Traditional deterministic forecasting methods can provide only a single point value and cannot give the degree of uncertainty associated with the forecast, thereby failing to provide information on predictive confidence. This study applied interval prediction for landslide displacement. Taking the Tanjiahe landslide of the Three Gorges Reservoir Area as an example and considering the impact of seasonal variations in reservoir level and rainfall, the uncertainties associated with landslide displacement prediction were quantified into prediction intervals (PIs) by a bootstrapped least-square support vector machine (LSSVM) method (B-LSSVM). The proposed method consists of three steps: First, the LSSVM and bootstrapping were combined to estimate the true regression means of landslide displacement and the variance with respect to model misspecification uncertainties. Second, a new LSSVM model optimized by a genetic algorithm (GA) was implemented to estimate the noise variance. Finally, the point prediction was derived from the regression means, and the PIs were constructed by combining the regression mean, the model variance, and the noise variance. We applied the proposed method to predict the displacement of four GPS monitoring points of the Tanjiahe landslide, and we comprehensively compared the prediction accuracy and the quality of the constructed PIs with benchmark methods. A simulation and performance comparison showed that the proposed method is a promising technique for providing accurate and reliable prediction results for landslide displacement.

Evaluating the Impact of Seasonal Variability on Groundwater Quality using Multivariate Analysis of Variance

Groundwater which constitutes high percent of the global fresh water is one of the most important sources of drinking water. When polluted, groundwater has deleterious effects on its users. Consequently, the quality and pollution of groundwater is a health concern in the world. The focus of the study is to evaluate the impact of seasonal variation on the quality of groundwater within the study areaHundred (100) boreholes spread to cover the study area were sampled. The water samples were analyzed using standard procedures for assessing drinking water qualities in order to determine the condition of groundwater quality within the study area. Statistical analysis of the groundwater quality data was done using weighted average index method to determine the water quality index and multivariate analysis of variance (MANOVA) to assess the impact of seasonal variation. Result of multivariate analysis of variance (MANOVA) which was employed to assess the presence of seasonal variability revealed that the calculated partial Eta squared of the Pillai’s trace statistics was 1.00 which indicates 100% variability among the dependent variables occasioned by seasonal change. Keywords: Multivariate statistics, Seasonal variation, Water quality index, Pillai’s trace statistics and Partial Eta squared. DOI : 10.7176/CMR/11-10-05 Publication date: December 31 st 2019

Seasonal variations effect on antioxidant compounds and their role in the adaptation of some halophytes at Wadi Gharandal, Southwest Sinai

The impact of seasonal variations on lipid peroxidation in terms of malondialdehyde (MDA) content, and contents of chlorophyll a and b, carotenoid, ascorbic acid content, proline content, glycine betaine content and total phenols content were assessed in seven halophytic representative species, viz., the shoot system of Halocnemum strobilaceum (Pall.) M. Bieb., Arthrocnemum macrostachyum (Moric.) K. Koch, Suaeda vermiculata Forssk. ex J. F. Gmel., Atriplex halimus L., Zygophyllum album L., Tammarix nilotica (Ehrenb.) Bunge, and Limonium pruinosum (L.) Chaz. Lipid peroxidation and glycine-betaine increased in summer, while chlorophyll a and b, and carotenoid decreased in all the species studied. During winter, the ascorbic acid content increased in all species, except in L. pruinosum, while total phenols content increased during summer except in Z. album. Positive correlations were recorded among carotenoids with chl. a, chl. b, ascorbic acid, proline and total phenols and also proline content with total phenols in the first four species belongs to Amaranthaceae. These results indicate that glycine betaine biosynthesis play a pivotal role in diluting the oxidative damage result in abiotic stress, especially in Amaranthaceae.

The influence of climate change on the escalating communal conflict between herdsmen and farmers: the case of the Fulani ethnic group in Nigeria

Current scientific evidence shows that human activities are causing interference at different levels in the global climate and availability of natural resources, and many authors already relate water scarcity to the increased risk of violent conflict, particularly in rural societies on the African continent. Climate disruptions caused by climate change are reflected on a regional and local scale, and the greatest impacts are already being felt in the poorest areas of the planet. Nigeria, Africa's most populous country, has been facing environmental problems in its territory that can be associated with climate change, such as rising temperatures, reduced rainfall and advancing desertification. Considering that all these phenomena have been worsening since the early twentieth century in Nigeria and, due to the escalating of violent conflicts since the beginning of the current century, the objective of this paper is to analyse how climate change can interfere in the conflict between herdsmen and farmers, as well as the possible impact of seasonal variation in rainfall on the dynamics of these communal conflicts. The study focused on literature review and the case study took place in four Nigerian states (Plateau, Benue, Taraba and Nasarawa) for the period 2010-2017, focusing on the communal conflict involving the Fulani ethnic group. The approach adopted was the inductive method in which the behaviour of rainfall in the study area was compared with the number of deaths resulting from the conflict, in addition to using geo-processing software to understand the spatial and temporal distribution of casualties. The theoretical framework used was that proposed by Thomas Homer-Dixon (1994) and the information was collected from primary sources, with consultation of qualitative and quantitative data, and from secondary sources through book reviews, publications and papers in scientific journals. While it is not yet possible to establish a direct and linear relationship between climate change and violent conflict, the revised literature indicates that competition for water and other natural resources in certain parts of Nigeria is increasing, and that the violent conflicts between Fulani herdsmen and farmers are increasing due to the dispute over access to water sources and grazing lands. Data analysis shows that in the study area there are 46.4% more deaths in the dry season (November to April) than in the rainy season (May to October). While there are still not enough elements to conclude that climate change is the primary cause of the conflict, the analysis reinforces the need, in certain contexts, particularly in developing countries with populations highly dependent on the primary sector of the economy, for the impacts of climate change to be seriously considered as a risk to human security.

Impacts of Seasonal Variation on Organochlorine Pesticides in the East China Sea and Northern South China Sea.

To investigate the characteristics of historic-use organochlorine pesticides (OCPs) in the marginal seawater of China, we examined the seasonal and spatial distributions of hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), and dichlorodiphenyltrichloroethane (DDTs) in the northern South China Sea (NSCS, 18-23° N) and East China Sea (ECS, 26-32° N). Seasonally, in the NSCS, the significantly higher concentrations (p < 0.05) of HCB, HCHs, and DDTs were found in summer, autumn, and summer through autumn, respectively. In the ECS, the higher concentrations were found in summer through winter, autumn, and summer. Spatially, HCB concentrations were significantly higher in the NSCS than in the ECS during all seasons except winter. During all four seasons, concentrations of HCHs were significantly higher in the NSCS than in the ECS. In summer and autumn, concentrations of DDTs were significantly higher in the NSCS than in the ECS, while no significant differences were found in spring and winter. Generally, regional usage, river-influenced coastal plumes, phytoplankton abundances, and ocean currents played crucial roles in the input, transport, degradation, and dilution of OCPs. These dynamic factors along with the seasonally alternating monsoon directly influenced the seasonal and spatial characteristics of OCPs. Furthermore, the profiles and diagnostic ratios of HCHs and DDTs revealed highly weathered OCP residues, attributed to eroded soils carried by surface runoff and long-range oceanic and atmospheric transport.

Impact of seasonal variations in Plasmodium falciparum malaria transmission on the surveillance of pfhrp2 gene deletions

Ten countries have reported pfhrp2/pfhrp3 gene deletions since the first observation of pfhrp2-deleted parasites in 2012. In a previous study (Watson et al., 2017), we characterised the drivers selecting for pfhrp2/3 deletions and mapped the regions in Africa with the greatest selection pressure. In February 2018, the World Health Organization issued guidance on investigating suspected false-negative rapid diagnostic tests (RDTs) due to pfhrp2/3 deletions. However, no guidance is provided regarding the timing of investigations. Failure to consider seasonal variation could cause premature decisions to switch to alternative RDTs. In response, we have extended our methods and predict that the prevalence of false-negative RDTs due to pfhrp2/3 deletions is highest when sampling from younger individuals during the beginning of the rainy season. We conclude by producing a map of the regions impacted by seasonal fluctuations in pfhrp2/3 deletions and a database identifying optimum sampling intervals to support malaria control programmes.

Comprehensive performance evaluation of various solar PV system configurations

This study presents a year-long comprehensive performance analysis of four distinct solar photovoltaic (SPV) system configurations with central inverter, micro inverter, fixed axis structure and dual axis sun tracker (DAST) structure installed at the Indian Institute of Technology Kharagpur, West Bengal, India. Technical and economic performance indices are used to analyse the impact of inverter technology and DAST structure using field data of one year. Specifically, technical parameters specified by IEC 61724 are used to compare simulated results with field data from June 2017 to May 2018. The difference between the simulated and measured values of all the configurations is mostly attributed to the variation in solar irradiance and module temperature data. For simulation study, daily and monthly average values are considered while daily instantaneous data are used for measured values. Comparison of measured values through energy yield, capacity factor and performance ratio (PR) indices has confirmed the superiority of dual axis micro inverter system configuration. Additionally, the impact of seasonal variation on PR values for all four system configurations is also analysed. Economic performance for 25 years of project life using payback period, net present value and levelised cost of energy indices concludes dual axis central inverter system configuration as the most economical.

Insight into the Contrasting Findings of Therapeutic Trials of Digital Ischaemic Manifestations of Systemic Sclerosis

Digital vascular complications are a major cause of disease-related morbidity in systemic sclerosis (SSc). Demonstrating treatment efficacy in the management of cutaneous vascular manifestations of SSc has been challenging. The contrasting findings of clinical trials of Raynaud’s phenomenon (RP) and digital ulcers (DU) for within-class medications have led to doubt on likely efficacy; with geographic variation in reimbursement policies and variation in clinical practice. In this paper, we compare the contrasting trials of phosphodiesterase inhibitors in the management of SSc-RP and endothelin receptor antagonists in the management of SSc-DU to help identify potential barriers for future successful clinical trials in these fields. Scrutiny of the contrasting clinical trials in these fields has identified a number of important differences in trial design and patient characteristics that may account for differences in clinical trial outcomes. These factors include differences in patient selection, impact of seasonal variation in weather, and the definitions applied to SSc manifestations. The contrasting findings of clinical trials of within-class medications for the management of digital vascular manifestations of SSc have been disappointing but can provide investigators with valuable insight into treatment response in SSc and the pre-requisites for future effective clinical trial design.

Seasonal Variation of Phyto-Constituents of Tea Leaves Affects Antiproliferative Potential

Objective: Tea (Camellia sinensis Linn.; family: Theaceae) is popular as a stimulant beverage across the globe and is also utilized as a functional antioxidant in alternative medicine. This study has evaluated the impact of seasonal variation on phyto-constituents of tea.Method: The antiproliferative potential of methanolic extracts of tea leaves collected in the rainy season (MECR) was compared with the extract of tea leaves collected in the autumn season (MECA) of the same mother plant. Evaluation of in vivo antitumor activity was carried out in adult female Swiss albino mice groups inoculated with Ehrlich ascites carcinoma (EAC) cells. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to compare efficacy of MECR with that of MECA in the EAC cell line. Both qualitative and quantitative tests for phytochemical constituents present in MECA and MECR were performed. Antitumor efficacy of both the extracts was determined by evaluating different tumor markers showing dose-dependent cytotoxicity.Results: Statistically significant reduction in EAC-induced tumor was observed in MECR treated mice compared to MECA treated ones. Cell decimation was significantly higher with MECR treatment, where restoration of different parameters including tissue structures returned to normal. Moreover, gas chromatography–mass spectrometry (GC-MS) study revealed the presence of cyclobarbital and benzazulene derivative in MECR, which is thought to be a novel source of these chemicals.Conclusions: To our knowledge, there is no report that has attempted to reveal nutritional changes in terms of efficacy and variation in anticancer constituents in tea leaves, plucked in two seasons. This study revealed a novel source of barbital and benzazulene derivative. The unique presence of cyclobarbital and benzazulene, as revealed from GC-MS data, in methanolic extract of tea leaves collected during the rainy season (MECR) may have contributed to its enhanced in vitro (adopting MTT assay) and in vivo (on EAC-infected Swiss albino mice) cytotoxicity vis-à-vis antiproliferative properties compared to methanolic extract of tea leaves collected during the autumn season (MECA). The nature of plucking leaves in the two selected seasons is different.

Impacts of seasonal variation and operating parameters on double-stage trommel performance

The high-level objective of this research was to quantify and assess impact of uncertainties of trommel screening with respect to feed-rate variation, clogging of screen apertures, and seasonal variation in waste characteristics, including particle size distribution (PSD) and composition using full-scale trials. A two-stage trommel screen which is operated at a municipal solid waste processing facility located in a cold region (Edmonton, Canada) was evaluated. The waste processed was co-mingled refuse with the recyclable material removed. The variation of size separation mass balance and recovery with respect to total and overs loading feed rate, season and operation time were monitored. The characteristics of the feedstock and separated waste streams were determined by sieve and compositional analyses. Separation and recovery results verified that the performance of the first stage where <5 cm of organic-rich waste was screened out, varied seasonally. Further, a strong linear correlation was obtained between recovery results and corresponding overs loading rate that varied between seasons. This correlation also varied within operation cycle during the winter trials due to clogging of screens. An equation is proposed to quantify clogging formation according to operation uptime and feed rate. Waste characterization results indicated the waste generated in the winter, spring, and summer had three distinct PSDs, especially the compostable fraction, contributing to the seasonality in trommel performance. In contrast, the PSD of the combustible fraction remained consistent in all seasons. This research successfully quantified the impact of uncertainties of full trommel operations in different seasons and during the operation cycle.

Impact of seasonal variation on lupeol content in latex of Calotropis gigantea R.Br. and Calotropis procera Ait.

Impact of seasonal variation on lupeol content in latex of Calotropis gigantea R.Br. and Calotropis procera Ait.

Impact of Seasons on Soil Physico-Chemical Properties and Tea Yields Based on Enriched Sheep Manure Used in Kericho, Kenya

Tea (Camellia sinensis (L) O. Kuntze) is a perennial crop grown for beverage consumption. Its production is the leading foreign exchange earner in Kenya contributing about 26% foreign exchange and 4% GDP. Nitrogen (N), Phosphorus (P) and potassium (K) are the recommended nutrients for tea production. However, their continuous use has been reported to have negative effect on soil physico-chemical properties and health. Sheep manure has been recommended in tea production for its soil pH buffering effect and increased tea yields. However, effects of sheep manure enriched with inorganic fertilizer on tea soils and yield have not been conclusively investigated. This study was established at KALRO—Tea Research Institute Kericho in Timbilil estate to determine the impact of seasonal variation on soil pysico-chemical properties and yields on enriched sheep manure used. Randomized complete block design (RCBD) experimental design was adopted with 14 treatments replicated thrice. The treatments were: control with no fertilizer use, NPK at 180 Kgs N/ha/yr, sheep manure only and two enriched sheep manure ratios of 4:1 and 8:1 which translates to a mixture of (4:1) 4 parts of sheep manure and 1 part of D.A.P inorganic fertilizer. Same applied to 8:1 ratio, respectively at rates of 60, 120, 180 and 240 Kgs N/ha once per year. Data were subjected to ANOVA in GenStat statistical package and means separated by Duncan’s multiple range tests at P ≤ 0.05 significance level. Results obtained showed that soil physico-chemical properties and tea yields were influenced significantly (P ≤ 0.05) by treatments applied. Soil available water and organic matter were higher on enriched sheep manure 4:1 at 240 rate used while soil porosity and bulk density were not significantly affected. Total N and P, increased with enriched sheep manure ratio of 4:1 at 240 rate while K+, Ca2+, Mg2+, Mn and pH increased with sole application of sheep manure at rate 180 and enriched sheep manure 8:1 at 180 rate. Tea yields increased with enriched sheep manure 4:1 ratios at the rates of 240. The findings recommend enriched sheep manure 4:1 ratio at 240 rates to be adopted by tea farmers within Kericho region. Further studies involving different geographical locations are proposed.

Impact of seasonal variation in meteorological conditions on dry eye severity.

PurposeTo compare dry eye (DE) diagnosis patterns by season in Miami vis-a-vis the US and examine differences in DE symptoms and signs by season in Miami.Patients and methodsUS veteran affairs (VA) patient visits with ICD-9 codes for DE (375.15) and routine medical examination (V70.0) from 2010 to 2013 were retrospectively analyzed to evaluate the seasonal pattern of DE diagnosis. A total of 365 patients with normal ocular anatomy were prospectively recruited from the Miami VA eye clinic from 2014 to 2016 for the assessment of symptoms and signs.ResultsWhile DE visit prevalence in Miami was about 10% lower than that of the rest of the country (22.5% vs 33.7%), Miami had roughly four times higher variability in DE visit prevalence throughout the year than the US. Peak values for DE symptoms in the Miami cohort aligned with peak DE prevalence seen in the retrospective sample, occurring in spring and fall. A similar, but less dramatic, pattern was noted with DE signs. The seasonal pattern in DE symptoms remained even after controlling for confounders including demographics and medication use.ConclusionDE symptoms, and to a lesser degree signs, varied by month, with the highest severity of symptoms occurring in spring and fall, which corresponded with peak allergy season and weather fluctuations, respectively. These findings have important implications for season-specific diagnosis, treatment, and management of DE.

Impact of Seasonal Variations on Foliage Penetration Experiment: A WSN-Based Device-Free Sensing Approach

Foliage penetration (FOPEN) has been found to be a critical mission for a variety of applications, ranging from surveillance to military. Recently, an emerging technology, namely wireless sensor network (WSN)-based device-free sensing (DFS), has been introduced to the domain of FOPEN. This technology only utilizes radio-frequency signals for target detection and classification; thus, no additional hardware is required, just a wireless transceiver. Although the feasibility of using this technology for human detection indoors has been explored to some extent, it is questionable if the same technology can be transferred to outdoors. As far as FOPEN is concerned, the impact of seasonal variations on detection accuracy can be severe. To address this concern, in this paper, an experiment is conducted in four seasons, and how to ensure reasonable detection accuracy with seasonal variations is intensively investigated. To fully evaluate the potential of using the WSN-based DFS for FOPEN, an impulse-radio ultrawideband technology-based prototype is used to collect data samples in different seasons. Unlike the conventional approach based on a combination of statistical properties of received-signal strength and a support vector machine, this approach adopts two special measures for performance enhancement. One measure is to use a higher order cumulant (HOC) algorithm for feature extraction, so that the impact on detection accuracy due to unwanted clutters can be minimized. The other one is to determine the optimal parameters of the classifier by means of a flower pollination algorithm. Consequently, the adverse effects on detection accuracy due to variations of weather conditions in four seasons can be accommodated. According to the experimental result, it is shown that the average classification accuracy of the presented approach can be improved by at least 20% under all seasons with an ensured robustness.

Impact of seasonal variations on the first ischemic events in patients with moyamoya disease

ObjectivesThis retrospective study aimed to explore the impact of seasonal variations on the first ischemic events in patients with moyamoya disease (MMD). Patients and MethodsBased on the first-time ischemic event occurrence, 113 patients, including 84 with cerebral infarction and 29 with transient ischemic attack, who were diagnosed with ischemic MMD were divided into four groups: spring (March–May), summer (June–August), autumn (September–November) and winter (December–February). The incidence of cerebral infarction was considered as the primary parameter. The impact of seasonal variations on the occurrence of cerebral infarction was analyzed by Poisson regression model and seasonal analysis. ResultsWhen summer was set as the reference, patients in summer were more significantly susceptible to develop cerebral infarction as compared with spring (IRR, 0.529, 95%CI, 0.299–0.937, p = 0.03), autumn (IRR, 0.441, 95%CI, 0.240–0.810, p < 0.01) and winter (0.500, 95%CI, 0.279–0.895, p = 0.02). The seasonality of the time series in summer (1.231) was substantially higher than that in the other three seasons (−0.269 in spring, −0.656 in autumn and −0.306 in winter). No discrepancy in either NIHSS or mRS scores at admission was observed among the four seasons. ConclusionPatients with MMD may be more vulnerable to cerebral infarction in summer compared with the other three seasons, and seasonal onset of cerebral infarction does not seem to be associated with the severity of neurological disability at admission.

A GIS-based method to define geographical determinants of environmental exposure to agricultural pesticides in France

Introduction Exposure to pesticides has been suggested as a risk factor for several diseases or adverse health outcomes. The use of geographic information systems (GIS) in epidemiological studies to y to assess environmental exposure to agricultural pesticides (EEAP) is growing. Residential proximity to agricultural crops is frequently used as a surrogate of EEAP. Previous studies have suggested that application of pesticides near residences results in contamination of indoor surfaces. US studies have recently reported a positive correlation between the proximity or crop acreage and the contamination of indoor dust by agricultural pesticides in nearby homes. There is however no validated and applicable model in France: the US model is based on pesticide use registries and adapted on large crops and local practices. However, most of these studies did not consider spatial information on environmental factors such as wind direction and physical barriers (structural or natural) to pesticide drift from the field to receptors. In France, the availability of public data on these aspects allows to describe the relationship between the proximity of agricultural areas and residential exposure to pesticides. We aimed to assess geographical determinants of the indoor dust contamination by agricultural pesticides in different crop areas (SIGEXPO project). Methods A GIS was developed for 239 households, from three different agricultural sectors (69 near orchards and cereals, 66 near cereals, 68 near vineyards) and an urban area (n = 36). For each residence, the GIS considers the agricultural land use, the proximity of household to agricultural zones (fields). For five different buffer sizes (250 m–1250 m), we used GIS to determine targeted crop acreage, prevailing winds, and vegetative, topographic and structural barriers to pesticides drift from crops. Two additional dimensions have been considered in the development of the GIS: prevailing winds direction that influence pesticide drift and obstacles that mitigate on pesticide drift from agricultural applications, i.e. the presence of topographical, vegetal (hedges, forests) or structural barriers (built areas). The effect of obstacles is reflected in the presence of topographical, vegetal (hedges, forests) or structural barriers (built areas). In parallel, both recent ( 6 month) indoor dust samples were collected from households without professional pesticide users and analyzed. Pesticide applicators were excluded from the study. Information household characteristics and domestic pesticide users were collected by questionnaire. Redundancy analyzes were conducted to define the geographical determinants that best explain the indoor dust concentrations of the 27 agricultural pesticides detected in more than 10% of study households. Results Overall, main determinants of agricultural pesticides contamination in indoor dust were crop acreage within 500 m (orchards) or 1000 m buffer size (vineyards and cereals), as well as prevailing winds, and the presence of vegetative barriers. Our different models explained up to 18.3% of the variability of the pesticide contamination in indoor dust. Conclusion While the explained variability remains modes overall, it was above or comparable to previous studies. The determinants identified should be taken into account in future GIS-based approaches aiming to assess EEAP in the French context. The approach developed to assess the impact of wind and barriers need to be validated on additional datasets. Future studies should include the analyses of the impact of seasonal variations into the geographical determinants selection.