The steady-state concentration of singlet oxygen within a lake (
1
O
2
SS
) is an important parameter that can affect the environmental half-life of pollutants and environmental fate modelling. ...However, values of
1
O
2
SS
are often determined for the near-surface of a lake, and these values typically do not represent the average over the epilimnia of lakes. In this work, the environmental and physical factors that have the largest impact on
1
O
2
SS
within lake epilimnia were identified. It was found that the depth of the epilimnion has the largest impact on depth-averaged
1
O
2
SS
, with a factor of 8.8 decrease in
1
O
2
SS
when epilimnion depth increases from 2 m to 20 m. The next most important factors are the wavelength-dependent singlet oxygen quantum yield relationship and the latitude of the lake, causing variations in
1
O
2
SS
by factors of 3.2 and 2.5 respectively, over ranges of representative values. For a set of representative parameters, the depth-averaged value of
1
O
2
SS
within an average epilimnion depth of 9.0 m was found to be 5.8 × 10
−16
M and the near-surface value of
1
O
2
SS
was found to be 1.9 × 10
−14
M. We recommend a range of 6 × 10
−17
to 5 × 10
−15
M as being more representative of
1
O
2
SS
values within the epilimnia of lakes globally and potentially more useful for estimating pollutant lifetimes than those calculated using
1
O
2
SS
values that correspond to near-surface, summer midday values. This work advances our understanding of
1
O
2
SS
inter-lake variability in the environment, and provides estimates of
1
O
2
SS
for practitioners and researchers to assess environmental half-lives of pollutants due to reaction with singlet oxygen.
1
O
2
SS
within lake epilimnia are highly affected by epilimnion depth and are barely affected by DOC concentration within the lake.
As more aquifer storage and recovery (ASR) systems are employed for management of water resources, the skillful operation of multiwell ASR systems has become very important to improve their ...performance. In this study, we developed MODFLOW and MT3DMS models to simulate a multiwell ASR system in a synthetic aquifer to assess effects of hydrogeological and operational factors on the performance of the multiwell ASR system. We evaluated a simplified (dual well) ASR system in comparison with complex system (three‐, four‐, five‐, and seven‐well systems). Recovery and energy efficiencies were calculated using the model simulations. Factors such as higher hydraulic conductivity and longitudinal dispersivity significantly reduced the recovery and energy efficiencies of the system. In contrast, increasing the volume of recharged water increased the recovery efficiency; however, the energy efficiency was reduced. Recovery and energy efficiencies also plummet when there is an increase in the underlying regional gradient and the designed storage duration. Operating the system multiple times can yield higher volume of potable water, but the energy efficiency may not vary significantly after the second operating cycle. Single‐well systems and multiwell systems exhibit similar responses to changes in physical factors, although operational factors have a more pronounced effect on the multiwell systems. One of the major findings was that fewer wells in a multiwell ASR system can yield higher volume of potable water and better output with respect to the electrical power being consumed. The results provide design engineers with guidelines for optimizing performance of the multiwell ASR systems.
Introduction
Glaucoma is known as multifactorial neurodegenerative disease with intraocular pressure (IOP) as main risk factor. Recent experimental studies showed an impact of corneal temperature on ...aqueous humour (AH) flow, thus potentially influencing IOP.1 Additionally, temperature was seen to influence fluidity of AH by changing its viscosity.2 As bench to bedside research, the aim of the present study was investigate a potential influence of ambient temperature on IOP in glaucoma patients.
Methods
Sixty‐four eyes of 64 glaucoma patients (34 male, 30 female) of the Erlangen Glaucoma Registry (NCT00494923; ISSN 2191‐5008, CS‐2011) were included between 11/17 and 08/18. All patients underwent a complete ophthalmological examination including Goldmann applanation tonometry (at 12.00 a.m). Daily local temperature (DT) was recorded. Subgroup analysis was done for a winter group (11/17–03/18; mean age: 63.6±12 years; 17 male, 15 female; mean defect 4.93±5.35 dB) and a summer group (04/2018–08/2018; mean age: 70.2±9.9 years; 17 male, 15 female; mean defect 4.68±5.08 dB).
Results
(I) Total IOP of all eyes was 13.61±3.8 mmHg. Subgroup analysis yielded a mean IOP of 14.3±3.6 mmHg in the winter group and 11.7±2.7 mmHg in the summer group. (II) Local DT was 13.96±11.1°C (‐6.8 ‐ +32.9°C) during the year. Winter local DT was measured as 3.28±4.8°C (11/17‐03/18). Summer local DT showed a mean of 24.11±3.7°C (04/18 ‐ 08/18). (III) Mean IOP was observed to be significantly higher in patients of the winter group compared to the summer group (p < 0.001).
Discussion
Experimental ex‐vivo studies suggested that cooler ambient temperatures ‘cools’ AH via corneal surface, decreasing AH fluidity. Thus, AH circulation is lowered with consecutive increase of IOP. Data of the present clinical study bridge these experimental findings, offering ambient temperature as novel influencing factor on IOP in glaucoma patients.
References
Colligris P, Perez de Lara MJ, Colligris B, Pintor J. Ocular Manifestations of Alzheimer’s and Other Neurodegenerative Diseases: The Prospect of the Eye as a Tool for the Early Diagnosis of Alzheimer’s Disease. Journal of ophthalmology 2018;2018:8538573.
Boussommier‐Calleja A, Li G, Wilson A, et al. Physical Factors Affecting Outflow Facility Measurements in Mice. Investigative ophthalmology & visual science 2015;56:8331‐8339.
The rapid development and increased use of wireless telecommunication technologies led to a substantial change of radio-frequency electromagnetic field (RF-EMF) exposure in the general population but ...little is known about temporal trends of RF-EMF in our everyday environment.
The objective of our study is to evaluate temporal trends of RF-EMF exposure levels in different microenvironments of three European cities using a common measurement protocol.
We performed measurements in the cities of Basel (Switzerland), Ghent and Brussels (Belgium) during one year, between April 2011 and March 2012. RF-EMF exposure in 11 different frequency bands ranging from FM (Frequency Modulation, 88MHz) to WLAN (Wireless Local Area Network, 2.5GHz) was quantified with portable measurement devices (exposimeters) in various microenvironments: outdoor areas (residential areas, downtown and suburb), public transports (train, bus and tram or metro rides) and indoor places (airport, railway station and shopping centers). Measurements were collected every 4s during 10–50min per environment and measurement day. Linear temporal trends were analyzed by mixed linear regression models.
Highest total RF-EMF exposure levels occurred in public transports (all public transports combined) with arithmetic mean values of 0.84V/m in Brussels, 0.72V/m in Ghent, and 0.59V/m in Basel. In all outdoor areas combined, mean exposure levels were 0.41V/m in Brussels, 0.31V/m in Ghent and 0.26V/m in Basel.
Within one year, total RF-EMF exposure levels in all outdoor areas in combination increased by 57.1% (p<0.001) in Basel by 20.1% in Ghent (p=0.053) and by 38.2% (p=0.012) in Brussels. Exposure increase was most consistently observed in outdoor areas due to emissions from mobile phone base stations. In public transports RF-EMF levels tended also to increase but mostly without statistical significance.
An increase of RF-EMF exposure levels has been observed between April 2011 and March 2012 in various microenvironments of three European cities. Nevertheless, exposure levels were still far below regulatory limits of each country. A continuous monitoring is needed to identify high exposure areas and to anticipate critical development of RF-EMF exposure at public places.
•Temporal trends of RF-EMF exposure in various outdoor and indoor microenvironments were investigated over one year.•Within one year mobile phone base station exposure levels increased in several Swiss and Belgian microenvironments.•In contrast to our hypothesis, mobile phone handset exposure did not increase in public transports.•RF-EMF exposure levels still remained substantially below the ICNIRP guidelines.
The Tarai region of Nepal is regarded as the food bowl of Nepal, and yet urban areas have increased in size at an average annual rate of 12% for the 30 years since 1988/1989, largely at the expense ...of prime agricultural land. Nepal is recognized internationally as highly sensitive to food security with 40% of its population undernourished. To aid future planning and reduce potential further loss of agricultural land and consequent increased food insecurity, we here investigated the previously unknown factors underlying this rapid urban expansion. We achieved this through analyses of land use and land cover (LULC) data, population, and climatic data, in association with focus group discussions and questionnaire surveys. We found that socioeconomic factors were perceived to have made the highest (62%) contribution to urbanization, particularly migration-led population growth and the economic opportunities offered by urban areas, followed by political factors (14.5%), physical factors (12%), and planning and policy factors (11.5%). In addition, climate and physiographic features make the area attractive for urban development along with favorable government plans and policies. Accelerated urban expansion during this period was particularly driven by mass migration due to political upheaval in the country resulting in rapid population and urban center growth. Of the total 293 urban centers in the country, the Tarai region includes 150 (51.2%) of which 77 (26.3%) are located in province 2 alone and accommodate 17.2% of Nepal’s households. This increasing urbanization trend is expected to continue in the future due to current socioeconomic and demographic factors. We hope our results which show what has driven past urbanization will aid future urban planning and management of the Tarai as well as other similar regions elsewhere in the world. We also identified that such rapid urban growth is largely at the cost of populations in rural areas with rural depopulation resulting in agriculture being abandoned in some areas. Given Nepal’s sensitivity to food security and lower food production, this will be an increasing problem for the future.
Sustainable agriculture with low inputs of chemicals and fertilizers has been recently attracting more attention from producers and researchers in the EU. The main reason for such attention is The ...European Green Deal—the EU’s latest growth strategy concerning environmental degradation and climate change. One of its main components is the Farm to Fork strategy, which especially features the reduction in pesticide and mineral fertilizer application and also supports the development of organic farming. At the same time, food demand is rising. These ambitious challenges require extensive research, development and innovation. Therefore, new non-chemical techniques for improving plant growth and resistance to biotic and abiotic stresses must be explored for their potential in this field. One of the most promising is the use of non-thermal plasma for such purposes. As this physical factor is a complex mixture of ions, atoms, electrons, radicals and molecules, its effect on plants and pathogens is also complex. This review presents different aspects of the effect of non-thermal plasma on seed germination, development of seedlings, plants and pathogens. The literature was explored to provide evidence for the possible use of non-thermal plasma for boosting plant growth and plant protection.
Under‐ice dissolved oxygen (DO) metabolism and DO depletion are poorly understood, limiting our ability to predict how changing winter conditions will affect lake ecosystems. We analyzed under‐ice DO ...dynamics based on high‐frequency (HF) data at two depths (5 and 25 m) for three winters (January–March 2014, 2015, and 2016) in oligotrophic Lake Tovel (1178 m above sea level; maximum depth 39 m). Specifically, we assessed diel metabolic rates based on HF data of DO, temperature, and light for winter 2016 and seasonal DO depletion rates based on HF data of DO for all three winters. For 2016, calculations of metabolic rates were possible only for 34% and 3% of days at 5 and 25 m, respectively; these metabolic rates generally indicated net heterotrophy at both depths. Low success in modeling metabolic rates was attributed to low diel DO variability and anomalous diel DO patterns, probably linked to under‐ice physical processes. Seasonal DO patterns for the three winters showed increasing, decreasing, or stable DO trends at 5 m while at 25 m patterns always showed decreasing DO trends but with different rates. Our multiyear study permitted us to hypothesize that the observed intraannual and interannual differences in DO depletion can be attributed to variable snow cover determining the penetration of radiation and thus photosynthesis. This study brings new insights to DO dynamics in ice‐covered systems, highlights the challenges linked to under‐ice lake metabolism, and advocates for a modeling approach that includes physical processes.
Plain Language Summary
More than half of the world's lakes freeze in winter, but scientists still know little about what happens under ice. A major challenge in dealing with winter conditions is the difficulty of sampling when snow and ice often restrict site accessibility. The use of underwater sensors that continuously measure temperature, oxygen, and light has partly overcome this obstacle. However in most lakes, sensors are removed during winter because ice breakup can damage this expensive equipment; Lake Tovel is one of the few lakes where sensors are deployed all year round. Oxygen is needed by organisms for respiration, and how much oxygen is still available in the lake when ice melts will have important implications for the rest of the year. We analyzed 3 years of under‐ice oxygen data and show that oxygen can increase at 5 m depth but always decreased at 25 m depth. Climate change predictions indicate less snow in the Alps and earlier ice breakup. We show how water movement and snow influence under‐ice oxygen. Our study brings new insights to oxygen dynamics in ice‐covered systems and highlights the challenges in understanding the biological and physical factors that influence oxygen in ice‐covered lakes.
Key Points
Under‐ice DO metabolism at a diel scale is challenging because DO patterns do not always follow those dictated by biological processes
Cluster analysis provided a way to choose appropriate days for metabolic calculations
Under‐ice DO depletion at a seasonal scale depends on snow cover, probably influencing photosynthesis
PET can reveal in vivo biological processes at the molecular level. PET-derived quantitative values have been used as a surrogate marker for clinical decision-making in numerous clinical studies and ...trials. However, quantitative values in PET are variable depending on technical, biological, and physical factors. The variability may have a significant impact on a study outcome. Appropriate scanner calibration and quality control, standardization of imaging protocols, and any necessary harmonization strategies are essential to make use of PET as a biomarker with low bias and variability. This review summarizes benefits, limitations, and remaining challenges for harmonization of quantitative PET, including whole-body PET in oncology, brain PET in neurology, PET/MR, and non-
18
F PET imaging. This review is expected to facilitate harmonization of quantitative PET and to promote the contribution of PET-derived biomarkers to research and development in medicine.
Purpose
Minimally Invasive Surgery (MIS) is demanding on the musculoskeletal and visual systems. Prevalence, severity and association of neck/shoulder problems and visual symptoms were examined among ...MIS surgeons. The associations of workplace and individual factors with these symptoms independently and combined were also examined.
Methods
MIS surgeons completed a comprehensive online survey inclusive of 52 questions about individual and workplace physical factors, neck/shoulder problems and visual symptoms. Binary logistic regression models were conducted to determine the associations of the neck/shoulder problems, visual symptoms and combined symptoms with workplace and individual factors.
Results
290 surgeons completed the survey. Neck/shoulder problems and visual symptoms were reported by 31.0% and 29.0%, respectively, 15.5% reported both problems. The prevalence and severity of neck/shoulder problems and visual symptoms were significantly associated (
p
< 0.001). Several workplace and individual factors were associated with these symptoms (
p
≤ 0.05).
Conclusions
Several factors in the workplace environment (temperature, asymmetrical weight bearing and forward head movement) and individual (being female and wearing vision correction glasses) were significantly associated with neck/shoulder problems and visual symptoms. Evaluation of different strategies to minimise the strain on the neck/shoulder region and the visual system is required.
During the past several decades, desertification and land degradation have become more and more serious in Mongolia. The drivers of land use/cover change (LUCC), such as population dynamics and ...climate change, are increasingly important to local sustainability studies. They can only be properly analyzed at small scales that capture the socio-economic conditions. Several studies have been carried out to examine the pattern of LUCC in Mongolia, but they have been focused on changes in single land types at a local scale. Although some of them were carried out at the national scale, the data interval is more than 10 years. A small-scale and year-by-year dataset of LUCC in Mongolia is thus needed for comprehensive analyses. We obtained year-by-year land use/cover changes in Mongolia from 1990 to 2021 using Landsat TM/OLI data. First, we established a random forest (RF) model. Then, in order to improve the classification accuracy of the misclassification of cropland, grassland, and built and barren areas, the classification and regression trees model (CART) was introduced for post-processing. The results show that 17.6% of the land surface has changed at least once among the six land categories from 1990 to 2021. While the area of barren land has significantly increased, the grassland and forest areas have exhibited a decreasing trend in the past 32 years. The other land types do not show promising changes. To determine the driving factors of LUCC, we applied an RF feature importance ranking to environmental factors, physical factors, socioeconomic factors, and accessibility factors. The mean annual precipitation (MAP), evapotranspiration (ET), mean annual air temperature (MAAT), DEM, GDP, and distance to railway are the main driving factors that have determined the distribution and changes in land types. Interestingly, unlike the global anti-V-shaped pattern, we found that the land use/cover changes show an N-shaped trend in Mongolia. These characteristics of land use/cover change in Mongolia are primarily due to the agricultural policies and rapid urbanization. The results present comprehensive land use/cover change information for Mongolia, and they are of great significance for policy-makers to formulate a scientific sustainable development strategy and to alleviate the desertification of Mongolia.
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