scholarly journals Stable Isotope Composition of River Waters across the World

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1760 ◽  
Author(s):  
Yi Nan ◽  
Fuqiang Tian ◽  
Hongchang Hu ◽  
Lixin Wang ◽  
Sihan Zhao
Keyword(s):  
Multiple Regression ◽  
Hydrological Cycle ◽  
Isotope Composition ◽  
Meta Analysis ◽  
Global Network ◽  
River Waters ◽  
Spatial Coverage ◽  
Ecological Patterns ◽  
Data Points ◽  
Patterns And Processes

Stable isotopes of O and H in water are meaningful indicators of hydrological and ecological patterns and processes. The Global Network of Isotopes in Precipitation (GNIP) and the Global Network of Isotopes in Rivers (GNIR) are the two most important global databases of isotopes in precipitation and rivers. While the data of GNIP is almost globally distributed, GNIR has an incomplete spatial coverage, which hinders the utilization of river isotopes to study global hydrological cycle. To fill this knowledge gap, this study supplements GNIR and provides a river isotope database with global-coverage by the meta-analysis method, i.e., collecting 17015 additional data points from 215 published articles. Based on the newly compiled database, we find that (1) the relationship between δ18O and δ2H in river waters exhibits an asymmetric imbricate feature, and bifurcation can be observed in Africa and North America, indicating the effect of evaporation on isotopes; (2) multiple regression analysis with geographical factors indicates that spatial patterns of river isotopes are quite different across regions; (3) multiple regression with geographical and meteorological factors can well predict the river isotopes, which provides regional regression models with r2 of 0.50 to 0.89, and the best predictors in different regions are different. This work presents a global map of river isotopes and establishes a benchmark for further research on isotopes in rivers.

Hydrologic dynamics and ecosystem structure

2003 ◽  
Vol 47 (6) ◽  
pp. 17-24 ◽  
Author(s):  
I. Rodríguez-Iturbe
Keyword(s):  
Hydrological Cycle ◽  
Limiting Factor ◽  
Ecosystem Structure ◽  
Nutrient Cycles ◽  
Stochastic Fluctuation ◽  
Ecological Patterns ◽  
Probabilistic Structure ◽  
Patterns And Processes ◽  
Hydrologic Inputs ◽  
Soil Climate

Ecohydrology is the science that studies the mutual interaction between the hydrological cycle and ecosystems. Such an interaction is especially intense in water-controlled ecosystems, where water may be a limiting factor, not only because of its scarcity, but also because of its intermittent and unpredictable appearance. Hydrologic dynamics is shown to be a crucial factor for ecological patterns and processes. The probabilistic structure of soil moisture in time and space is presented as the key linkage between soil, climate and vegetation dynamics. Nutrient cycles, vegetation coexistence and plant response to environmental conditions are all intimately linked to the stochastic fluctuation of the hydrologic inputs driving an ecosystem.

scholarly journals The O and H stable isotope composition of freshwaters in the British Isles. 1. Rainfall

2003 ◽  
Vol 7 (2) ◽  
pp. 163-181 ◽  
Author(s):  
W. G. Darling ◽  
J. C. Talbot
Keyword(s):  
Hydrological Cycle ◽  
Isotope Composition ◽  
Global Network ◽  
British Isles ◽  
Winter Rainfall ◽  
Stable Isotopic ◽  
Excess Parameter ◽  
Seasonal Basis ◽  
Autumn And Winter ◽  
Relationship Of

Abstract. An understanding of the hydrological cycle in stable isotopic terms requires the characterisation of rainfall. This paper reviews existing and new data for the British Isles. Rainfall at the Wallingford (Oxfordshire) collection station was collected daily from November 1979 to October 1980. Large variations in isotopic content were noted, sometimes from day to day. Winter rainfall was similar to summer in amount, and only slightly depleted isotopically. Amount and temperature correlations with δ18O were generally low, only the autumn and winter temperature relationships being significant. A 20-year monthly dataset from 1982 to 2001 for Wallingford gives the following regression: δ2H = 7.0δ18O + 1.2, a slope somewhat below the world meteoric line but consistent with the those from other long-term stations in NW Europe. The data showed uncorrelated maxima and minima for each year, but rather more consistent amount-weighted averages. Although there is only a small difference in gradient between summer and winter rainfall values, when plotted against the month of the year there are clear changes in the values of both isotopes, and the δ2H-δ18O relationship as demonstrated by the d-excess parameter. The isotope-amount correlation is low but significant, with summer months appearing to be well-correlated when considered in terms of month of the year. On this same seasonal basis temperature has a strong correlation throughout the year, giving a positive δ18O-temperature relationship of 0.25 ‰ per °C change. The Wallingford monthly record is compared with data from Keyworth (Nottinghamshire) and the Valentia station of the GNIP (IAEA-WMO Global Network for Isotopes in Precipitation) in SW Ireland. While not large, differences between the stations are broadly attributable to the balance between maritime and continental influences. Over the period September 1981 to August 1982 the maximum number of monthly collection stations was operating across the British Isles. While a comparison of the sites serves mostly to illustrate the variability of British weather in space and time, there is clear isotopic evidence for the predominance of frontal rainfall in winter and convective rainfall in summer. The effect of altitude on isotopic content was measured within a high-relief stream catchment in Scotland. The best correlations occurred during winter, when an average relationship of approximately –0.30 ‰ δ18O per 100 m increase in altitude was observed. It is well established that rainfall isotopic composition changes in response to alterations in climate. However these changes are difficult to detect isotopically in the short term, even when the changes are indexed, e.g. in the form of the NAO (North Atlantic Oscillation). The brief duration of rainfall isotope records is a further hindrance; for the British Isles proxies such as tree-ring cellulose may have some value in extending the record back. Keywords: stable isotopes, rainfall,British Isles

A Survey on Internet of Things : Applications and Layered Wise Security Issues

2019 ◽  
pp. 171-180
Author(s):  
Uppuluri Sirisha ◽  
G. Lakshme Eswari
Keyword(s):  
Quality Of Life ◽  
Internet Of Things ◽  
Security And Privacy ◽  
Global Network ◽  
Business Growth ◽  
Paper Briefly ◽  
Smart Meters ◽  
Security Issues ◽  
Data Points

This paper briefly introduces Internet of Things(IOT) as a intellectual connectivity among the physical objects or devices which are gaining massive increase in the fields like efficiency, quality of life and business growth. IOT is a global network which is interconnecting around 46 million smart meters in U.S. alone with 1.1 billion data points per day[1]. The total installation base of IOT connecting devices would increase to 75.44 billion globally by 2025 with a increase in growth in business, productivity, government efficiency, lifestyle, etc., This paper familiarizes the serious concern such as effective security and privacy to ensure exact and accurate confidentiality, integrity, authentication access control among the devices.

scholarly journals Low skeletal muscle mass predicts relevant clinical outcomes in head and neck squamous cell carcinoma. A meta analysis

2021 ◽  
Vol 13 ◽  
pp. 175883592110088
Author(s):  
Alexey Surov ◽  
Andreas Wienke
Keyword(s):  
Skeletal Muscle ◽  
Squamous Cell Carcinoma ◽  
Postoperative Complications ◽  
Cell Carcinoma ◽  
Head And Neck ◽  
Clinical Outcomes ◽  
Multiple Regression ◽  
Skeletal Muscle Mass ◽  
Meta Analysis ◽  
Simple Regression

Background: The purpose of this meta-analysis was to analyze the influence of sarcopenia, defined as low skeletal muscle mass, on clinical outcomes in patients with head and neck squamous cell carcinoma (HNSCC) based on a large sample. Methods: The MEDLINE, EMBASE, and SCOPUS databases were screened for associations between sarcopenia and clinical outcomes in HNSCC up to December 2020. Overall, 27 studies met the inclusion criteria. The methodological quality of the studies involved was checked according to the QUADAS instrument. The meta-analysis was undertaken using RevMan 5.3 software. DerSimonian and Laird random-effects models with inverse-variance weights were used to account for heterogeneity between the studies. Results: The 27 included studies comprised 7704 patients with different HNSCCs. The cumulative calculated frequency among the studies was 42.0% [95% confidence interval (CI) 35.34–48.65]. Sarcopenia was associated with occurrence of severe postoperative complications, odds ratio (OR) 4.79, 95% CI (2.52–9.11), p < 0.00001. Sarcopenia predicted disease-free survival (DFS), simple regression: hazard ratio (HR) 2.00, 95% CI (1.63–2.45), p < 0.00001, multiple regression: HR 1.64, 95% CI (1.33–2.03), p < 0.00001. Also, sarcopenia was associated with lower overall survival (OS), simple regression: HR 1.96, 95% CI (1.71–2.24), p < 0.00001, multiple regression: HR = 1.87, 95% CI (1.53–2.29), p < 0.00001. In patients who underwent definitive chemotherapy and/or radiation, sarcopenia predicted lower OS (simple regression), HR 1.95, 95% CI (1.61–2.36), p < 0.00001, multiple regression: HR = 1.51, 95% CI (1.17–1.94), p < 0.002). In patients with primary surgical strategy with or without adjuvant radio-chemotherapy, sarcopenia was associated with lower OS (simple regression), HR 2.21, 95% CI (1.72–2.84), p < 0.00001, multiple regression: HR = 2.05, 95% CI (1.55–2.72), p < 0.00001). Conclusion: The cumulative prevalence of sarcopenia in HNSCC is 42.0%. Sarcopenia is an independent risk factor for OS and DFS in patients with HNSCC who undergo curative therapy. Sarcopenia is associated with the occurrence of severe postoperative complications.

scholarly journals Investigating late Holocene variations in hydroclimate and the stable isotope composition of precipitation using southern South American peatlands: an hypothesis

2012 ◽  
Vol 8 (5) ◽  
pp. 1457-1471 ◽  
Author(s):  
T. J. Daley ◽  
D. Mauquoy ◽  
F. M. Chambers ◽  
F. A. Street-Perrott ◽  
P. D. M. Hughes ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Air Temperature ◽  
Regional Differences ◽  
Late Holocene ◽  
Isotope Composition ◽  
Precipitation Amount ◽  
Surface Air Temperature ◽  
Global Network ◽  
Stable Isotope Composition ◽  
Δd And Δ18o

Abstract. Ombrotrophic raised peatlands provide an ideal archive for integrating late Holocene records of variations in hydroclimate and the estimated stable isotope composition of precipitation with recent instrumental measurements. Modern measurements of mean monthly surface air temperature, precipitation, and δD and δ18O-values in precipitation from the late twentieth and early twenty-first centuries provide a short but invaluable record with which to investigate modern relationships between these variables, thereby enabling improved interpretation of the peatland palaeodata. Stable isotope data from two stations in the Global Network for Isotopes in Precipitation (GNIP) from southern South America (Punta Arenas, Chile and Ushuaia, Argentina) were analysed for the period 1982 to 2008 and compared with longer-term meteorological data from the same locations (1890 to present and 1931 to present, respectively). δD and δ18O-values in precipitation have exhibited quite different trends in response to local surface air temperature and precipitation amount. At Punta Arenas, there has been a marked increase in the seasonal difference between summer and winter δ18O-values. A decline in the deuterium excess of summer precipitation at this station was associated with a general increase in relative humidity at 1000 mb over the surface of the Southeast Pacific Ocean, believed to be the major vapour source for the local precipitation. At Ushuaia, a fall in δ18O-values was associated with an increase in the mean annual amount of precipitation. Both records are consistent with a southward retraction and increase in zonal wind speed of the austral westerly wind belt. These regional differences, observed in response to a known driver, should be detectable in peatland sites close to the GNIP stations. Currently, insufficient data with suitable temporal resolution are available to test for these regional differences over the last 3000 yr. Existing peatland palaeoclimate data from two sites near Ushuaia, however, provide evidence for changes in the late Holocene that are consistent with the pattern observed in modern observations.

scholarly journals Estimation of carcass weight of Hanwoo (Korean native cattle) as a function of body measurements using statistical models and a neural network

2020 ◽  
Vol 33 (10) ◽  
pp. 1633-1641
Author(s):  
Dae-Hyun Lee ◽  
Seung-Hyun Lee ◽  
Byoung-Kwan Cho ◽  
Collins Wakholi ◽  
Young-Wook Seo ◽  
...  
Keyword(s):  
Neural Network ◽  
Multiple Regression ◽  
Partial Least Square ◽  
Least Square ◽  
Partial Least Square Regression ◽  
Carcass Weight ◽  
Body Measurements ◽  
Least Square Regression ◽  
Data Points ◽  
Hanwoo Cattle

Objective: The objective of this study was to develop a model for estimating the carcass weight of Hanwoo cattle as a function of body measurements using three different modeling approaches: i) multiple regression analysis, ii) partial least square regression analysis, and iii) a neural network.Methods: Data from a total of 134 Hanwoo cattle were obtained from the National Institute of Animal Science in South Korea. Among the 372 variables in the raw data, 20 variables related to carcass weight and body measurements were extracted to use in multiple regression, partial least square regression, and an artificial neural network to estimate the cold carcass weight of Hanwoo cattle by any of seven body measurements significantly related to carcass weight or by all 19 body measurement variables. For developing and training the model, 100 data points were used, whereas the 34 remaining data points were used to test the model estimation.Results: The R2 values from testing the developed models by multiple regression, partial least square regression, and an artificial neural network with seven significant variables were 0.91, 0.91, and 0.92, respectively, whereas all the methods exhibited similar R2 values of approximately 0.93 with all 19 body measurement variables. In addition, relative errors were within 4%, suggesting that the developed model was reliable in estimating Hanwoo cattle carcass weight. The neural network exhibited the highest accuracy.Conclusion: The developed model was applicable for estimating Hanwoo cattle carcass weight using body measurements. Because the procedure and required variables could differ according to the type of model, it was necessary to select the best model suitable for the system with which to calculate the model.

scholarly journals Global trends in downward surface solar radiation from spatial interpolated ground observations during 1961-2019

2021 ◽  
pp. 1-56
Author(s):  
Menghan Yuan ◽  
Thomas Leirvik ◽  
Martin Wild
Keyword(s):  
Solar Radiation ◽  
Spatial Interpolation ◽  
Hydrological Cycle ◽  
Explanatory Power ◽  
Surface Solar Radiation ◽  
Global Trends ◽  
Cloud Coverage ◽  
Crucial Component ◽  
Spatial Coverage ◽  
Global Dimming

AbstractDownward surface solar radiation (SSR) is a crucial component of the Global Energy Balance, affecting temperature and the hydrological cycle profoundly, and it provides crucial information about climate change. Many studies have examined SSR trends, however they are often concentrated on specific regions due to limited spatial coverage of ground based observation stations. To overcome this spatial limitation, this study performs a spatial interpolation based on a machine learning method, Random Forest, to interpolate monthly SSR anomalies using a number of climatic variables (various temperature indices, cloud coverage, etc.), time point indicators (years and months of SSR observations), and geographical characteristics of locations (latitudes, longitudes, etc). The predictors that provide the largest explanatory power for interannual variability are diurnal temperature range and cloud coverage. The output of the spatial interpolation is a 0:5° ×0:5° monthly gridded dataset of SSR anomalies with complete land coverage over the period 1961-2019, which is used afterwards in a comprehensive trend analysis for i) each continent separately, and ii) the entire globe.The continental level analysis reveals the major contributors to the global dimming and brightening. In particular, the global dimming before the 1980s is primarily dominated by negative trends in Asia and North America, while Europe and Oceania have been the two largest contributors to the brightening after 1982 and up until 2019.

scholarly journals Fragmented Landscape, Fragmented Knowledge: A Synthesis of Renosterveld Ecology and Conservation

2019 ◽  
Vol 46 (2) ◽  
pp. 171-179 ◽  
Author(s):  
Emmeline N Topp ◽  
Jacqueline Loos
Keyword(s):  
Cape Floristic Region ◽  
Fragmented Landscape ◽  
Biodiversity Hotspots ◽  
Current State ◽  
Ecological Patterns ◽  
Local Patch ◽  
Populated Region ◽  
Patterns And Processes ◽  
First Time ◽  
Effective Conservation

SummaryKnowledge of ecological patterns and processes is key to effective conservation of biodiversity hotspots under threat. Renosterveld is one of the most critically endangered habitats in the biologically unique Cape Floristic Region, South Africa. For the first time, we map and synthesize the current state of knowledge on renosterveld ecology and conservation. We investigated 132 studies for the themes, locations and taxa of renosterveld research and the fragmentation, threats, recommendations and barriers to renosterveld conservation. More studies focused on plants than any other taxa (48% of articles) and are conducted mostly in larger, intact renosterveld fragments. The most commonly identified threat to renosterveld was agricultural intensification; conservation recommendations spanned improved farming practices, formal protection and local patch management. Conservation implementation has been piecemeal and has depended largely on the goodwill of landowners, which can be constrained by costs of conservation measures and a lack of suitable restoration means. Citizen science is a promising potential solution to some barriers. Fragmented knowledge in such a transformed and relatively densely populated region highlights the scale of knowledge gaps for other biodiversity hotspots and has implications for ongoing conservation work.

scholarly journals A Meta-Analysis of Spearman’s Hypothesis Tested on Latin-American Hispanics, Including a New Way to Correct for Imperfectly Measuring the Construct of g

Psych ◽  
2019 ◽  
Vol 1 (1) ◽  
pp. 101-122
Author(s):  
Jan te Nijenhuis ◽  
Michael van den Hoek ◽  
Joep Dragt
Keyword(s):  
Latin American ◽  
Meta Analysis ◽  
Data Points ◽  
The Difference

Spearman’s hypothesis states that the difference in intelligence between groups is a function of the g loadings of the subtests, where larger differences are found on tests with higher g loadings. This finding has consistently been supported on various groups. In this study we look at samples of Latin-American Hispanics in comparison to Whites. We carried out a meta-analysis based on 14 data points and a total of 16,813 Latin-American Hispanics, including a new way to correct for imperfectly measuring the construct of g. Spearman’s hypothesis was strongly supported with a mean r of 0.63. After correction for various statistical artifacts this value became rho = 0.91. Therefore, we conclude that Spearman’s hypothesis also holds true for White/Latin-American Hispanic differences.

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