scholarly journals High-frequency NO<sub>3</sub><sup>−</sup> isotope (δ<sup>15</sup>N, δ<sup>18</sup>O) patterns in groundwater recharge reveal that short-term land use and climatic changes influence nitrate contamination trends

2018 ◽  
Author(s):  
Martin Suchy ◽  
Leonard I. Wassenaar ◽  
Gwyn Graham ◽  
Bernie Zebarth
Keyword(s):  
Land Use ◽  
Groundwater Recharge ◽  
High Frequency ◽  
Poultry Manure ◽  
Primary Source ◽  
Climatic Changes ◽  
Nitrate Contamination ◽  
Short Term

Abstract. Poultry manure is the primary source of nitrate (NO3−) exceedances in the transboundary Abbotsford-Sumas aquifer (Canada-USA) based on synoptic surveys two decades apart, but serious questions remained about seasonal and spatial aspects of agricultural nitrate fluxes to the aquifer to help better focus remediation efforts. We conducted over 700 monthly δ15N and δ18O of nitrate assays, focusing on newly recharged groundwater (

scholarly journals High-frequency NO<sub>3</sub><sup>−</sup> isotope (<i>δ</i><sup>15</sup>N, <i>δ</i><sup>18</sup>O) patterns in groundwater recharge reveal that short-term changes in land use and precipitation influence nitrate contamination trends

2018 ◽  
Vol 22 (8) ◽  
pp. 4267-4279 ◽  
Author(s):  
Martin Suchy ◽  
Leonard I. Wassenaar ◽  
Gwyn Graham ◽  
Bernie Zebarth
Keyword(s):  
Land Use ◽  
High Frequency ◽  
Management Practices ◽  
Near Field ◽  
Poultry Manure ◽  
Nitrate Contamination ◽  
Short Term ◽  
Nitrate Sources ◽  
Isotope Data ◽  
Decadal Scale

Abstract. Poultry manure is the primary cause of nitrate (NO3-) exceedances in the transboundary Abbotsford–Sumas aquifer (ASA; Canada–USA) based on synoptic surveys two decades apart, but questions remained about seasonal and spatial aspects of agricultural nitrate fluxes to the aquifer to help better focus remediation efforts. We conducted over 700 monthly δ15N and δ18O of nitrate assays, focusing on shallow groundwater (< 5 years old) over a 5-year period to gain new insight on spatio-temporal sources and controls of groundwater nitrate contamination. NO3- concentrations in these wells ranged from 1.3 to 99 mg N L−1 (n=1041) with a mean of 16.2±0.4 mg N L−1. The high-frequency 15N and 18O isotope data allowed us to identify three distinctive NO3- source patterns: (i) primarily from synthetic fertilizer, (ii) dynamic changes in nitrate due to changes in land use, and (iii) from a mix of poultry manure and fertilizer. A key finding was that the source(s) of nitrate in recharge could be quickly influenced by short-term near-field management practices and stochastic precipitation events, which ultimately impact long-term nitrate contamination trends. Overall, the isotope data affirmed a subtle decadal-scale shift in agricultural practices from manure increasingly towards fertilizer nitrate sources; nevertheless, poultry-derived N remains a predominant source of nitrate contamination. Because the aquifer does not generally support denitrification, remediation of the Abbotsford–Sumas aquifer is possible only if agricultural N sources are seriously curtailed, a difficult proposition due to longstanding high-value intensive poultry and raspberry and blueberry operations over the aquifer.

Prior Return Effect in Indian Stock Market: An Intra-day Analysis

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Vanita Tripathi ◽  
Shalini Aggarwal
Keyword(s):  
Stock Market ◽  
Stock Prices ◽  
High Frequency ◽  
Good News ◽  
High Frequency Data ◽  
Short Term ◽  
Fund Managers ◽  
News Events ◽  
Return Effect ◽  
Indian Stock Market

In a first of this kind, this paper examines the issue of prior return effect in Indian stock market in intra-day analysis using high frequency data. We document that in Indian stock market, security returns exhibit a reversal in their direction within few minutes of extreme price rises as well as price falls. However the speed with which the correction takes place is slightly different for good news events and bad news events. Indian investors tend to be optimistic as they immediately bring stock prices up following unjustified price falls but take time to bring stock prices down following unjustified price rises. These findings lend a further support to short-term overreaction literature. More importantly, these findings serve as a proof of predictability of the direction of future stock prices and consequent returns on an intra-day basis. It forwards important investment implications for traders, fund managers, and investors at large.

scholarly journals Small Floating Target Detection Method Based on Chaotic Long Short-Term Memory Network

2021 ◽  
Vol 9 (6) ◽  
pp. 651
Author(s):  
Yan Yan ◽  
Hongyan Xing
Keyword(s):  
High Frequency ◽  
Short Term Memory ◽  
Detection Method ◽  
Low Frequency ◽  
Sea Clutter ◽  
Short Term ◽  
Term Memory ◽  
Memory Network ◽  
Long Short Term Memory ◽  
Small Targets

In order for the detection ability of floating small targets in sea clutter to be improved, on the basis of the complete ensemble empirical mode decomposition (CEEMD) algorithm, the high-frequency parts and low-frequency parts are determined by the energy proportion of the intrinsic mode function (IMF); the high-frequency part is denoised by wavelet packet transform (WPT), whereas the denoised high-frequency IMFs and low-frequency IMFs reconstruct the pure sea clutter signal together. According to the chaotic characteristics of sea clutter, we proposed an adaptive training timesteps strategy. The training timesteps of network were determined by the width of embedded window, and the chaotic long short-term memory network detection was designed. The sea clutter signals after denoising were predicted by chaotic long short-term memory (LSTM) network, and small target signals were detected from the prediction errors. The experimental results showed that the CEEMD-WPT algorithm was consistent with the target distribution characteristics of sea clutter, and the denoising performance was improved by 33.6% on average. The proposed chaotic long- and short-term memory network, which determines the training step length according to the width of embedded window, is a new detection method that can accurately detect small targets submerged in the background of sea clutter.

scholarly journals Effect of short-term exposure to particulate air pollution on heart rate variability in normal-weight and obese adults

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Luyi Li ◽  
Dayu Hu ◽  
Wenlou Zhang ◽  
Liyan Cui ◽  
Xu Jia ◽  
...  
Keyword(s):  
Heart Rate ◽  
Air Pollution ◽  
Heart Rate Variability ◽  
High Frequency ◽  
Normal Weight ◽  
High Frequency Power ◽  
Short Term ◽  
Particulate Air Pollution ◽  
Short Term Exposure ◽  
Frequency Power

Abstract Background The adverse effects of particulate air pollution on heart rate variability (HRV) have been reported. However, it remains unclear whether they differ by the weight status as well as between wake and sleep. Methods A repeated-measure study was conducted in 97 young adults in Beijing, China, and they were classified by body mass index (BMI) as normal-weight (BMI, 18.5–24.0 kg/m2) and obese (BMI ≥ 28.0 kg/m2) groups. Personal exposures to fine particulate matter (PM2.5) and black carbon (BC) were measured with portable exposure monitors, and the ambient PM2.5/BC concentrations were obtained from the fixed monitoring sites near the subjects’ residences. HRV and heart rate (HR) were monitored by 24-h Holter electrocardiography. The study period was divided into waking and sleeping hours according to time-activity diaries. Linear mixed-effects models were used to investigate the effects of PM2.5/BC on HRV and HR in both groups during wake and sleep. Results The effects of short-term exposure to PM2.5/BC on HRV were more pronounced among obese participants. In the normal-weight group, the positive association between personal PM2.5/BC exposure and high-frequency power (HF) as well as the ratio of low-frequency power to high-frequency power (LF/HF) was observed during wakefulness. In the obese group, personal PM2.5/BC exposure was negatively associated with HF but positively associated with LF/HF during wakefulness, whereas it was negatively correlated to total power and standard deviation of all NN intervals (SDNN) during sleep. An interquartile range (IQR) increase in BC at 2-h moving average was associated with 37.64% (95% confidence interval [CI]: 25.03, 51.51%) increases in LF/HF during wakefulness and associated with 6.28% (95% CI: − 17.26, 6.15%) decreases in SDNN during sleep in obese individuals, and the interaction terms between BC and obesity in LF/HF and SDNN were both statistically significant (p <  0.05). The results also suggested that the effects of PM2.5/BC exposure on several HRV indices and HR differed in magnitude or direction between wake and sleep. Conclusions Short-term exposure to PM2.5/BC is associated with HRV and HR, especially in obese individuals. The circadian rhythm of HRV should be considered in future studies when HRV is applied. Graphical abstract

scholarly journals An Easy-to-Use Method for Assessing Nitrate Contamination Susceptibility in Groundwater

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Daniela Ducci
Keyword(s):  
Land Use ◽  
Nitrate Contamination ◽  
Environmental Data ◽  
Susceptibility Map ◽  
Anthropogenic Pressure ◽  
Large Area ◽  
Combination Process ◽  
Arithmetic Average ◽  
Agricultural Potential ◽  
High Concentrations

This research presents a methodology for assessing nitrate contamination susceptibility in groundwater using thematic maps, derived mainly from the land use map and from statistical data available at national/regional institutes of statistics (especially demographic and environmental data). The methodology was applied in a large area of southern Italy encompassing 4 alluvial and volcanic groundwater bodies, with high concentrations of NO3. The Potential Nitrate Contamination is believed to derive from three sources: agricultural, urban, and periurban. The first one is related to the use of fertilizers. For this reason the land use map was reclassified on the basis of the crop requirements in terms of fertilizers to obtain the Agricultural Potential Nitrate Contamination (APNC) map. The urban source considers leakages from the sewage network and, consequently, it depends on the anthropogenic pressure, expressed by the population density, particularly concentrated in the urbanized areas (Urban Potential Nitrate Contamination (UPNC) map). The periurban sources include unsewered areas, especially present in the periurban context, where illegal sewage connections coexist with on-site sewage disposal (cesspools, septic tanks, and pit latrines) (Periurban Potential Nitrate Contamination (PuPNC) map). The Potential Nitrate Contamination (PNC) map is produced by overlaying the APNC, UPNC, and PuPNC maps. The map combination process is straightforward, being an algebraic combination: the output values are the arithmetic average of the input values. The final pollution susceptibility (RISK) map is obtained by combining the PNC map with the groundwater contamination vulnerability (GwVu) map. The methodology, successfully applied in the study area with a relatively good correlation between the nitrate contamination susceptibility map and the nitrate distribution in groundwater, appears to be effective and have a significant potential for being applied worldwide.

Land‐use comparison of depression‐focussed groundwater recharge in the Canadian prairies

2021 ◽  
Vol 35 (9) ◽  
Author(s):  
Laura R. Morgan ◽  
Masaki Hayashi ◽  
Edwin E. Cey
Keyword(s):  
Land Use ◽  
Groundwater Recharge ◽  
Canadian Prairies

Cibenzoline for High-Frequency Ventricular Arrhythmias: A Short-Term Comparison With Quinidine and a Long-Term Follow-up

1987 ◽  
Vol 27 (4) ◽  
pp. 283-287 ◽  
Author(s):  
Prasad R. Palakurthy ◽  
Claudio Maldonado ◽  
Gurbachan Sohi ◽  
Nancy C. Flowers
Keyword(s):  
High Frequency ◽  
Ventricular Arrhythmias ◽  
Short Term ◽  
Long Term Follow Up
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