scholarly journals Atmospheric Δ<sup>17</sup>O(NO<sub>3</sub><sup>−</sup>) reveals nocturnal chemistry dominates nitrate production in Beijing haze

2018 ◽  
Author(s):  
Pengzhen He ◽  
Zhouqing Xie ◽  
Xiyuan Chi ◽  
Xiawei Yu ◽  
Shidong Fan ◽  
...  
Keyword(s):  
Fine Particle ◽  
Isotopic Exchange ◽  
Sampling Period ◽  
Relative Importance ◽  
Nitrate Production ◽  
Atmospheric Nitrate ◽  
Particle Pollution ◽  
The Mean ◽  
Mass Increase ◽  
Rapid Mass

Abstract. The rapid mass increase of atmospheric nitrate is a critical driving force for the occurrence of fine-particle pollution (referred to as haze hereafter) in Beijing. However, the exact mechanisms for this rapid increase of nitrate mass has been not well constrained from field observations. Here we present the first observations of the oxygen-17 excess of atmospheric nitrate (Δ17O(NO3−)) collected in Beijing haze to reveal the relative importance of different nitrate formation pathways, and we also present the simultaneously observed δ15N(NO3−). During our sampling period, 12 h-averaged mass concentrations of PM2.5 varied from 16 to 323 μg m−3 with a mean of (141 ± 88 (1σ)) μg m−3, with nitrate ranging from 0.3 to 106.7 μg m−3. The observed Δ17O(NO3−) ranged from 27.5 ‰ to 33.9 ‰ with a mean of (30.6 ± 1.8) ‰ while δ15N(NO3−) ranged from −2.5 ‰ to 19.2 ‰ with a mean of (7.4 ± 6.8) ‰. Δ17O(NO3−)-constrained calculations suggest nocturnal pathways (N2O5 + H2O/Cl− and NO3 + HC) dominated nitrate production during polluted days (PM2.5 ≥ 75 μg m−3) with the mean possible fraction of 56 − 97 %. For δ15N(NO3−), we found that a combined effect of variability in NOX sources and isotopic exchange between NO and NO2 is likely to be most responsible for its variations. Our results illustrate the potentiality of isotope in tracing NOX sources and nitrate formation pathways, future modelling work with the constraint of isotope data reported here may further improve our understanding of nitrogen cycle during haze.

scholarly journals Atmospheric Δ<sup>17</sup>O(NO<sub>3</sub><sup>−</sup>) reveals nocturnal chemistry dominates nitrate production in Beijing haze

2018 ◽  
Vol 18 (19) ◽  
pp. 14465-14476 ◽  
Author(s):  
Pengzhen He ◽  
Zhouqing Xie ◽  
Xiyuan Chi ◽  
Xiawei Yu ◽  
Shidong Fan ◽  
...  
Keyword(s):  
Fine Particle ◽  
Driving Force ◽  
Sampling Period ◽  
Field Observations ◽  
Relative Importance ◽  
Nitrate Production ◽  
Atmospheric Nitrate ◽  
Particle Pollution ◽  
Mass Increase ◽  
Rapid Mass

Abstract. The rapid mass increase of atmospheric nitrate is a critical driving force for the occurrence of fine-particle pollution (referred to as haze hereafter) in Beijing. However, the exact mechanisms for this rapid increase of nitrate mass have not been well constrained from field observations. Here we present the first observations of the oxygen-17 excess of atmospheric nitrate (Δ17O(NO3-)) collected in Beijing haze to reveal the relative importance of different nitrate formation pathways, and we also present the simultaneously observed δ15N(NO3-). During our sampling period, 12 h averaged mass concentrations of PM2.5 varied from 16 to 323 µg m−3 with a mean of (141±88(1SD)) µg m−3, with nitrate ranging from 0.3 to 106.7 µg m−3. The observed Δ17O(NO3-) ranged from 27.5 ‰ to 33.9 ‰ with a mean of (30.6±1.8) ‰, while δ15N(NO3-) ranged from −2.5 ‰ to 19.2 ‰ with a mean of (7.4±6.8) ‰. Δ17O(NO3-)-constrained calculations suggest nocturnal pathways (N2O5+H2O/Cl- and NO3+HC) dominated nitrate production during polluted days (PM2.5≥75 µg m−3), with a mean possible fraction of 56–97 %. Our results illustrate the potentiality of Δ17O in tracing nitrate formation pathways; future modeling work with the constraint of isotope data reported here may further improve our understanding of the nitrogen cycle during haze.

The valuation of elephant sightings in protected areas.

2021 ◽  
pp. 191-203
Author(s):  
Andrea Saayman ◽  
Melville Saayman
Keyword(s):  
South Africa ◽  
Willingness To Pay ◽  
Contingent Valuation ◽  
Protected Areas ◽  
National Parks ◽  
Big Five ◽  
The Other ◽  
Relative Importance ◽  
The Mean ◽  
Preferred Species

Abstract The research presented in this chapter determines the value that tourists on safari in protected areas in South Africa attach to elephant sightings and the relative importance of the elephant sighting compared with the other species in the Big Five. The study also determines whether tourists take the increased poaching of elephants - also in South Africa - into account when revealing their choice. Using information from five surveys conducted at different parks in South Africa from 2011 to 2013 and again in 2019, the elephant was found to be the fourth preferred species in the Big Five. The exception is Addo Elephant National Park, where the elephants are the second most preferred species. To determine the value that tourists attached to a sighting, contingent valuation was used. Although approximately a quarter to a third of respondents indicated positive amounts for a sighting across the years, the mean willingness to pay (WTP) reflects the scarcity of the species. The elephant is relatively abundant in all the parks and, in many instances, much easier to spot than the leopard or lion. It is therefore not surprising that the mean valuation of a sighting is much lower than that of the leopard and lion throughout all the years. Although tougher economic conditions in the country also influence WTP, it was found that tourists to South Africa's National Parks do not yet take the increased poaching of elephants into account when revealing their choice, nor in their valuation.

scholarly journals Actividad reproductiva y dieta de Hemidactylus frenatus (Sauria: Gekkonidae) en el norte de Colombia

2017 ◽  
Vol 57 (36) ◽  
pp. 459
Author(s):  
Jorge A. Díaz-Pérez ◽  
Alcides C. Sampedro-Marín ◽  
Martha P. Ramírez-Pinilla
Keyword(s):  
Diet Composition ◽  
Sampling Period ◽  
Reproductive Activity ◽  
Climatic Conditions ◽  
Relative Importance ◽  
Adult Males ◽  
Adult Females ◽  
Ecological Aspects ◽  
Environmental Availability ◽  
Hemidactylus Frenatus

Despite its success as an invasive species, little is known about the ecological aspects of the gekkonid lizard Hemidactylus frenatus in Colombia. In the present study the size at maturity, sexual dimorphism, reproductive activity, and diet composition of a population of this species in an urban locality of Northern Colombia were determined. We conducted eleven samplings from September 2011 to August 2012 in buildings of the municipality of Sincelejo. A total of 264 specimens H. frenatus were captured, 112 were adult females, 133 adult males and 19 juveniles. Males reach sexual maturity at a smaller size (snout-vent length) than females (males: 35.7 mm; females: 42.7 mm), also they are larger and have proportionally larger heads and mouths than females. Males were reproductive throughout the year; although testicular volume varied significantly between samples, this variation was not associated with body size and precipitation in the study area. Reproductive adult females were found during all the sampling period. Females have an invariable clutch size of two eggs and we found no differences in the diameter and weight of eggs in each oviduct. The diet of H. frenatus is varied, with Diptera, Hemiptera and Formicidae being the prey types with the greatest relative importance values. Individuals of both sexes consume a similar volume and number of prey. Thus, the studied population of H. frenatus has continuous reproductive activity and a generalist-opportunistic feeding behavior. The climatic conditions of the study area, environmental availability of prey and intrinsic features of this species appear to be responsible for their abundance and colonizing success in this and other localities.

HOW IMPORTANT IS THE SIZE OF A REPRINT ORDER?

2003 ◽  
Vol 19 (4) ◽  
pp. 711-714 ◽  
Author(s):  
Sally Hopewell ◽  
Mike Clarke
Keyword(s):  
Randomized Trials ◽  
Citation Index ◽  
Control Group ◽  
Relative Importance ◽  
The Mean ◽  
Control Set ◽  
Number Of Citations ◽  
The Impact ◽  
Very High ◽  
Subsequent Literature

Objectives: This study aims to assess the impact of articles with very high reprint orders (“high-reprint articles”) by measuring their citation in the subsequent literature as compared with a control group of articles.Methods: The twenty-one articles (published in the Lancet in 1998) with reprint orders of over 10,000 were matched with a control set of twenty-one articles with smaller reprint orders. The Science Citation Index was used to obtain the number of citations for each of the forty-two articles.Results: The twenty-one high-reprint articles were cited 2,548 times; the mean number of citations was 121 (range, 3 to 499 citations per article). Five of the twenty-one high-reprint articles had more than 200 citations, but seven (33%) were cited twenty-five times or fewer. The twenty-one control articles were cited 986 times; the mean number of citations was forty-seven (range, 1 to 165). Fifteen (71%) of the twenty-one control articles were cited twenty-five times or fewer. Thirteen of the high-reprint articles were reports of randomized trials with a mean of 163 citations. In the control articles, six were reports of randomized trials with a mean of eighty-eight citations.Conclusions: Articles with a high-reprint order were cited more frequently than other articles. However, some high-reprint articles were cited infrequently. If the size of a reprint order is related to the importance of an article, those articles with very high reprint orders may, therefore, be perceived as more important. Further research is needed to explore other aspects of the relative importance and impact of high-reprint articles.

Structured Antedependence Models for Functional Mapping of Multiple Longitudinal Traits

2005 ◽  
Vol 4 (1) ◽  
Author(s):  
Wei Zhao ◽  
Wei Hou ◽  
Ramon C. Littell ◽  
Rongling Wu
Keyword(s):  
Genetic Correlations ◽  
Covariance Matrices ◽  
Growth Trajectories ◽  
Relative Importance ◽  
Hybrid Progeny ◽  
Linkage Groups ◽  
Stem Height ◽  
Pleiotropic Qtl ◽  
The Mean ◽  
Mean Vector

In this article, we present a statistical model for mapping quantitative trait loci (QTL) that determine growth trajectories of two correlated traits during ontogenetic development. This model is derived within the maximum likelihood context, incorporated by mathematical aspects of growth processes to model the mean vector and by structured antedependence (SAD) models to approximate time-dependent covariance matrices for longitudinal traits. It provides a quantitative framework for testing the relative importance of two mechanisms, pleiotropy and linkage, in contributing to genetic correlations during ontogeny. This model has been employed to map QTL affecting stem height and diameter growth trajectories in an interspecific hybrid progeny of Populus, leading to the successful discovery of three pleiotropic QTL on different linkage groups. The implications of this model for genetic mapping within a broader context are discussed.

Condition bias of hunter-shot mallards (Anas platyrhynchos)

1986 ◽  
Vol 64 (3) ◽  
pp. 599-601 ◽  
Author(s):  
Hamilton Greenwood ◽  
Robert G. Clark ◽  
Patrick J. Weatherhead
Keyword(s):  
Anas Platyrhynchos ◽  
Sampling Period ◽  
Poor Condition ◽  
Collection Period ◽  
The Mean ◽  
Using Data ◽  
Band Recovery

We tested the hypothesis that hunters using decoys disproportionately shot ducks in poor condition. We compared weights of 316 hunter-shot mallards (Anas platyrhynchos) with those of 156 mallards we collected by jump or pass shooting at a roost. Data were subdivided by age, sex, and sampling period. In support of the hypothesis, in 11 of 12 comparisons, hunter-shot ducks weighed less than ducks collected at the roost and those differences were significant for five of the seven largest samples. Also consistent with the hypothesis, weights of hunter-shot birds were less variable than weights of birds collected at the roost in 9 of 12 comparisons. Through the fall collection period, the mean weight of ducks shot by hunters remained constant, while the weight of ducks sampled at the roost increased by 5.4%. Our results support the argument that caution must be exercised when using data from hunter-shot waterfowl for management programs based on band-recovery analysis or for any other purpose for which a condition bias could influence the interpretation of those data.

Effect of rate of hemorrhage on release of ACTH in cats

1986 ◽  
Vol 250 (1) ◽  
pp. E76-E81
Author(s):  
D. A. Bereiter ◽  
A. M. Zaid ◽  
D. S. Gann
Keyword(s):  
Slow Rate ◽  
Plasma Concentrations ◽  
Sampling Period ◽  
Cortisol Concentration ◽  
Rapid Rate ◽  
Progressive Decrease ◽  
Acute Hemorrhage ◽  
Arterial Blood ◽  
Repeated Sampling ◽  
The Mean

The effect of rate of blood loss by acute hemorrhage (H) on adrenocorticotropin (ACTH) and cortisol plasma concentrations was assessed in anesthetized cats. Arterial blood was withdrawn at a rapid rate (10% blood vol/min) or at a slow rate (2%/min), and responses were compared across three volumes of H (10, 20, and 30% of blood vol). After rapid rate of H, ACTH increased in proportion to volume of H (r = 0.669, P less than 0.001) with a mean elevation of 124 +/- 27, 267 +/- 102, and 950 +/- 195 pg/ml for 10, 20, and 30% H, respectively. Slow rate of H evoked a significant increase in ACTH that was not proportional to volume of H (r = 0.314, P greater than 0.10), and the mean change during the post-H sampling period was 611 +/- 166, 828 +/- 302, and 1,070 +/- 239 pg/ml for 10, 20, and 30% H, respectively. Control animals showed no change in ACTH to the repeated sampling paradigm. Rapid H evoked an immediate decrease in mean arterial pressure (MAP) with a post-H recovery of MAP inversely proportionate to volume of H (r = -0.552, P less than 0.01). Slow H caused a progressive decrease in MAP with no significant post-H recovery of MAP at any volume of H. Cortisol concentration increased in proportion to volume of H after rapid H (r = 0.515, P less than 0.025), but not after slow H.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Philopatry to Stopover Site and Body Condition of Transient Reed Warblers During Autumn Migration Through Israel

The Condor ◽  
2000 ◽  
Vol 102 (2) ◽  
pp. 441-444 ◽  
Author(s):  
Kobi Merom ◽  
Yoram Yom-Tov ◽  
Robin McClery
Keyword(s):  
Body Mass ◽  
Body Condition ◽  
Wing Length ◽  
First Year ◽  
Sahara Desert ◽  
Stopover Site ◽  
Acrocephalus Scirpaceus ◽  
The Mean ◽  
High Degree ◽  
Mass Increase

Abstract Philopatry to stopover site and changes in body condition of migrating Reed Warblers Acrocephalus scirpaceus were studied in Bet Shean Valley, Israel, where warblers were netted throughout the year. Although the majority of birds were seen only once, the proportion of transients seen twice or more in different years is comparable to the figure for summer residents returning between years, indicating a high degree of philopatry among transients. Transients get heavier with longer duration of stay, up to about 15 days, after which body mass increase appears to level off at about 3 g. Change in body condition, taken to be body mass divided by wing length, also was noted, albeit of less significance. The mean date of arrival in the autumn of birds in their first year was about 20 days later than that of older birds. Reed Warblers use their time effectively to replenish their body mass and improve their condition before starting the dangerous crossing of the Sahara Desert.

Fluoride in Saliva and Oral Mucosa after Brushing with 1,450 or 5,000 ppm Fluoride Toothpaste

2019 ◽  
Vol 53 (6) ◽  
pp. 675-681 ◽  
Author(s):  
Line Staun Larsen ◽  
Vibeke Baelum ◽  
Alan Richards ◽  
Bente Nyvad
Keyword(s):  
Oral Mucosa ◽  
Fluoride Concentration ◽  
Sampling Period ◽  
Tooth Brushing ◽  
Selective Electrode ◽  
Fluoride Level ◽  
Fluoride Toothpaste ◽  
Single Tooth ◽  
The Mean ◽  
Healthy Participants

The aim was to measure and compare fluoride concentrations in oral mucosa and saliva following a single brushing with either 1,450 or 5,000 ppm fluoride toothpaste. Fourteen healthy participants provided saliva and oral mucosa samples in the morning before tooth brushing. Then participants brushed their teeth with 1,450 ppm fluoride toothpaste, and saliva and mucosa samples were collected after 1, 2, 4, and 6 h. The experiment was repeated 3–7 days later with 5,000 ppm fluoride toothpaste. All samples were analyzed for fluoride using an ion-selective electrode adapted for microanalysis. Pre-brushing fluoride concentrations were higher in mucosa (mean1,450 0.26 ppm and mean5,000 0.20 ppm) than in saliva (mean1,450 0.08 ppm and mean5,000 0.07 ppm). The mean fluoride concentrations increased in both mucosa and saliva following a single brushing with both 1,450 ppm (meanmuc1,450 (1 h) 1.15 ppm, meansal1,450 (1 h) 0.33 ppm) and 5,000 ppm fluoride toothpaste (meanmuc5,000 (1 h) 3.21 ppm and meansal5,000 (1 h) 0.90 ppm). At 6 h, the fluoride concentrations had returned to pre-brushing levels. Across the 6-h sampling period the fluoride concentration in saliva was statistically significantly 1.4 times higher following brushing with 5,000 ppm compared with 1,450 ppm fluoride toothpaste. For mucosa, this ratio was only 1.1 and not statistically significant. In conclusion, the fluoride level in oral buccal mucosa is higher than in saliva and follows the same fluoride clearance pattern as in saliva. Over the initial 6-h period following a single tooth brushing, the ratio of the fluoride concentration in mucosa to that in saliva is independent of the fluoride concentrations in the toothpastes used.

Variations in the concentrations of free amino acids in the plasma of the dairy cow at parturition

1972 ◽  
Vol 39 (3) ◽  
pp. 355-364 ◽  
Author(s):  
R. Verbeke ◽  
E. Roets ◽  
G. Peeters
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Free Amino ◽  
Milk Protein ◽  
Sampling Period ◽  
Aminobutyric Acid ◽  
Amino Acid Utilization ◽  
Amino Acid Levels ◽  
The Mean ◽  
Peak Value

SummaryThe plasma levels of individual amino acids were studied in 6 dairy cows from 4 days before to 3 days after calving. During this sampling period, the concentrations of 13 amino acids showed significant changes. The levels of several amino acids were depressed markedly in the sample collected immediately before calving. Following parturition, the concentration of most amino acids gradually returned to values obtained 3 days before calving. The glutamine and alanine contents of the plasma rose to a peak value 1 day after calving and subsequently decreased. The mean concentrations of glycine and α-aminobutyric acid did not change before parturition but rose significantly thereafter. These observations are discussed in terms of amino-acid utilization for milk protein synthesis and gluconeogenesis at the onset of lactation. The changes in plasma amino acid levels appear to be synchronized with those reported for prolactin and progesterone in the 24 h before parturition. This may indicate an important influence of both hormones on the lactogenic process in the cow. The highly significant correlations obtained between the concentrations of 14 individual amino acids are discussed.

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