scholarly journals Atmospheric and snow nitrate isotope systematics at Summit, Greenland: the reality of the post-depositional effect

2021 ◽  
Author(s):  
Zhuang Jiang ◽  
Joel Savarino ◽  
Becky Alexander ◽  
Joseph Erbland ◽  
Jean-Luc Jaffrezo ◽  
...  
Keyword(s):  
Seasonal Pattern ◽  
Ice Core ◽  
First Year ◽  
Nitrate Isotopes ◽  
Linear Relationships ◽  
Surface Snow ◽  
Nitrate Deposition ◽  
The Difference ◽  
Mass Dependent ◽  
Isotope Systematics

Abstract. The effect of post–depositional processing on the preservation of snow nitrate isotopes at Summit, Greenland remains a subject of debate which hinders the interpretations of ice–core nitrate concentrations and isotope records. Here we present the first year–round observations of atmospheric aerosol nitrate and its isotopic compositions at Summit, and compare them with published surface snow and snowpack observations. The atmospheric δ15N(NO3–) remained negative throughout the year, ranging from –3.1 ‰ to –47.9 ‰ with a mean of (–14.8 ± 7.3) ‰, and displayed no apparent seasonality that is different from the distinct seasonal δ15N(NO3–) variations observed in snowpack. The spring average aerosol δ15N(NO3–) was (–17.9 ± 8.3) ‰, significantly depleted compared to snowpack spring average of (4.6 ± 2.1) ‰, with surface snow δ15N(NO3–) of (–6.8 ± 0.5) ‰ that is in between. The differences in aerosol, surface snow and snowpack δ15N(NO3–) are best explained by the photo-driven post–depositional processing of snow nitrate, with potential contributions from fractionation during nitrate deposition. In contrast to δ15N(NO3–), the atmospheric Δ17O(NO3–) was of similar seasonal pattern and magnitude of change to that in snowpack, suggesting little to no changes in Δ17O(NO3–) from photolysis, consistent with previous modeling results. The atmospheric δ18O(NO3–) varied similarly as atmospheric Δ17O(NO3–), with summer low and winter high values. However, the difference between atmospheric and snow δ18O(NO3–) was larger than that of Δ17O(NO3–), and the linear relationships between δ18O/Δ17O(NO3–) were different for atmospheric and snowpack samples. This suggests the oxygen isotopes are also affected before preservation in the snow at Summit, but the degree of change for δ18O(NO3–) is larger than that of Δ17O(NO3–) given that photolysis is a mass-dependent process.

scholarly journals Archival processes of the water stable isotope signal in East Antarctic ice cores

2017 ◽  
Author(s):  
Mathieu Casado ◽  
Amaelle Landais ◽  
Ghislain Picard ◽  
Thomas Münch ◽  
Thomas Laepple ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Climate Models ◽  
Ice Core ◽  
Ice Cores ◽  
Climatic Conditions ◽  
Antarctic Plateau ◽  
Surface Snow ◽  
Rayleigh Distillation ◽  
The Difference ◽  
Ice Core Records

Abstract. The oldest ice core records are obtained from the East Antarctic plateau. Water isotopes records are key to reconstructing past climatic conditions over the ice sheet and at the evaporation source. The accuracy of climate reconstructions depends on knowledge of all the processes affecting water vapour, precipitation and snow isotopic compositions. Fractionation processes are well understood and can be integrated in Rayleigh distillation and isotope enabled climate models. However, a quantitative understanding of processes potentially altering the snow isotopic composition after the deposition is still missing. In low accumulation sites, such as those found in Antarctica, these poorly constrained processes are likely to play a significant role and limit the interpretation of isotopic composition. Here, we combine observations of isotopic composition in the vapour, the precipitation, the surface snow and the buried snow from Dome C, a deep ice core site on the East Antarctic Plateau. At the seasonal scale, we suggest a significant impact of metamorphism on surface snow isotopic signal compared to the initial precipitation signal. Particularly, in summer, exchanges of water molecules between vapour and snow are driven by the sublimation/condensation cycles at the diurnal scale. Using highly resolved isotopic composition profiles from pits in five Antarctic sites, we identify common patterns, despite different accumulation rates, which cannot be attributed to the seasonal variability of precipitation. Altogether, the difference in the signals observed in the precipitation, surface snow and buried snow isotopic composition constitute evidences of post-deposition processes affecting ice core records in low accumulation areas.

scholarly journals Differential Influence of Age on the Relationship between Genetic Mismatch and A(H1N1)pdm09 Vaccine Effectiveness

Viruses ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 619
Author(s):  
Lirong Cao ◽  
Shi Zhao ◽  
Jingzhi Lou ◽  
Hong Zheng ◽  
Renee W. Y. Chan ◽  
...  
Keyword(s):  
Age Groups ◽  
The Elderly ◽  
Vaccine Effectiveness ◽  
Amino Acid Mutation ◽  
Epidemic Season ◽  
Vaccine Component ◽  
Linear Relationships ◽  
The Difference ◽  
Middle Aged Adults ◽  
The Relationship

Assessment of influenza vaccine effectiveness (VE) and identification of relevant influencing factors are the current priorities for optimizing vaccines to reduce the impacts of influenza. To date, how the difference between epidemic strains and vaccine strains at genetic scale affects age-specific vaccine performance remains ambiguous. This study investigated the association between genetic mismatch on hemagglutinin and neuraminidase genes and A(H1N1)pdm09 VE in different age groups with a novel computational approach. We found significant linear relationships between VE and genetic mismatch in children, young adults, and middle-aged adults. In the children’s group, each 3-key amino acid mutation was associated with an average of 10% decrease in vaccine effectiveness in a given epidemic season, and genetic mismatch exerted no influence on VE for the elderly group. We demonstrated that present vaccines were most effective for children, while protection for the elderly was reduced and indifferent to vaccine component updates. Modeling such relationships is practical to inform timely evaluation of VE in different groups of populations during mass vaccination and may inform age-specific vaccination regimens.

Non-linear dynamics, chaos, complexity and enclaves in granitoid magmas

1996 ◽  
Vol 87 (1-2) ◽  
pp. 217-223 ◽  
Author(s):  
James Flinders ◽  
John D. Clemens
Keyword(s):  
Deterministic Chaos ◽  
Interfacial Area ◽  
Two Dimensions ◽  
Mixing Processes ◽  
Nd Isotope ◽  
Natural Systems ◽  
Non Linear ◽  
The Difference ◽  
Magma System ◽  
Isotope Systematics

ABSTRACT:Most natural systems display non-linear dynamic behaviour. This should be true for magma mingling and mixing processes, which may be chaotic. The equations that most nearly represent how a chaotic natural system behaves are insoluble, so modelling involves linearisation. The difference between the solution of the linearised and ‘true’ equation is assumed to be small because the discarded terms are assumed to be unimportant. This may be very misleading because the importance of such terms is both unknown and unknowable. Linearised equations are generally poor descriptors of nature and are incapable of either predicting or retrodicting the evolution of most natural systems. Viewed in two dimensions, the mixing of two or more visually contrasting fluids produces patterns by folding and stretching. This increases the interfacial area and reduces striation thickness. This provides visual analogues of the deterministic chaos within a dynamic magma system, in which an enclave magma is mingling and mixing with a host magma. Here, two initially adjacent enclave blobs may be driven arbitrarily and exponentially far apart, while undergoing independent (and possibly dissimilar) changes in their composition. Examples are given of the wildly different morphologies, chemical characteristics and Nd isotope systematics of microgranitoid enclaves within individual felsic magmas, and it is concluded that these contrasts represent different stages in the temporal evolution of a complex magma system driven by nonlinear dynamics. If this is true, there are major implications for the interpretation of the parts played by enclaves in the genesis and evolution of granitoid magmas.

scholarly journals Distribution and Driving Mechanism of N2O in Sea Ice and Its Underlying Seawater during Arctic Melt Season

Water ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 145
Author(s):  
Jian Liu ◽  
Liyang Zhan ◽  
Qingkai Wang ◽  
Man Wu ◽  
Wangwang Ye ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Ice Core ◽  
The Arctic ◽  
First Year ◽  
Driving Mechanism ◽  
Biogeochemical Processes ◽  
Ice Melting ◽  
Detailed Mechanism ◽  
The Arctic Ocean

Nitrous oxide (N2O) is the third most important greenhouse gas in the atmosphere, and the ocean is an important source of N2O. As the Arctic Ocean is strongly affected by global warming, rapid ice melting can have a significant impact on the N2O pattern in the Arctic environment. To better understand this impact, N2O concentration in ice core and underlying seawater (USW) was measured during the seventh Chinese National Arctic Research Expedition (CHINARE2016). The results showed that the average N2O concentration in first-year ice (FYI) was 4.5 ± 1.0 nmol kg−1, and that in multi-year ice (MYI) was 4.8 ± 1.9 nmol kg−1. Under the influence of exchange among atmosphere-sea ice-seawater systems, brine dynamics and possible N2O generation processes at the bottom of sea ice, the FYI showed higher N2O concentrations at the bottom and surface, while lower N2O concentrations were seen inside sea ice. Due to the melting of sea ice and biogeochemical processes, USW presented as the sink of N2O, and the saturation varied from 47.2% to 102.2%. However, the observed N2O concentrations in USW were higher than that of T-N2OUSW due to the sea–air exchange, diffusion process, possible N2O generation mechanism, and the influence of precipitation, and a more detailed mechanism is needed to understand this process in the Arctic Ocean.

scholarly journals Pola Musiman Kunjungan Wisatawan Mancanegara Ke Bali

2021 ◽  
Vol 14 (2) ◽  
pp. 73-90
Author(s):  
Addin Maulana ◽  
Chamma Fitri Putri Pradjwalita Koesfardani
Keyword(s):  
Seasonal Pattern ◽  
Method Of Calculation ◽  
Gini Coefficients ◽  
Tourism Marketing ◽  
Foreign Tourist ◽  
Drastic Increase ◽  
Seasonality Index ◽  
Insignificant Difference ◽  
The Difference ◽  
Allocation Strategies

The seasonal pattern of tourist arrivals is an important element that must be observed in making policies in the field of tourism marketing. By using the method of calculation, the Seasonality Ratio, Gini Coefficients, and Seasonality Index, this study aims to identify seasonal patterns of foreign tourist arrivals to Bali during the past 5 years. This study shows that: First, foreign tourists’ arrivals to Bali showed insignificant levels of variation and an equation of seasonal variations patterns is found in 2015, 2016, and 2019. Second, foreign tourist arrivals to Bali had a distribution per month that is relatively evenly distributed, with low seasonal rates, or the difference between monthly arrivals has an insignificant difference in value. Third, peak season of foreign tourists’ arrivals to Bali was concentrated in July with a drastic increase from the previous month and accompanied by a slowing decline towards the off-peak season. So, it is necessary to do an appropriate marketing and resource allocation strategies to optimize each seasonal phase.

scholarly journals THE EFFECT OF BLINDFOLD GAME ON STUDENTS’ VOCABULARY ACHIEVEMENT AT SMP NEGERI 13 KENDARI

2020 ◽  
Vol 5 (3) ◽  
pp. 200
Author(s):  
Andi An-Nisaa Arfin ◽  
Kamaluddin Kamaluddin ◽  
Wa Ode Fatmawati
Keyword(s):  
Junior High School ◽  
Alternative Hypothesis ◽  
First Grade ◽  
First Year ◽  
First Year Students ◽  
Comparison Research ◽  
Significant Difference ◽  
Post Test ◽  
The Difference ◽  
Vocabulary Achievement

The purpose of conducting this research is to examine the difference NGain scores between students who learn vocabulary with Blindfold Game and students who learn vocabulary without Blindfold Game at the first year students of SMP Negeri 13 Kendari. The samples of this research are the first grade four (VII-4) and the first grade three (VII-3) which consists of 27 students for each class. This research is conducted in comparison research design that consists of experimental class (VII-4) and controll class (VII-3). The data of this research are collected by giving pre-test and post-test in two classes (VII-4 & VII-3). The result shows that there is an improvement of the students’ vocabulary achievement. Independent samples t-test shows that, there is a significant difference in the Ngain scores for experimental class ( M = 60.08,  SD = 9.36 ) and controll class ( M = 20.41, SD = 14.56 ), t (52) = 11.904, p (0.000) < 0.05. Therefore, it can be concluded that the value of Sig (2 tailed) is lower than the significance α value (0.000 < 0.05). In other words, alternative hypothesis (H1) is accepted and the null hypothesis (H0) is rejected. It means that the Blindfold game can enrich students’ vocabulary achievement for Junior High School Student.

scholarly journals Effectiveness of riluzole in the treatment of amyotrophic lateral sclerosis

2021 ◽  
Author(s):  
Renato Puccioni Sohler ◽  
Gabriel Pinto Mendonça ◽  
Rodrigo Cesar Carvalho Freitas ◽  
José Roberto Ribas
Keyword(s):  
Amyotrophic Lateral Sclerosis ◽  
Survival Rate ◽  
Motor Neuron ◽  
Placebo Treatment ◽  
First Year ◽  
Advanced Stage ◽  
Mesh Terms ◽  
Student Test ◽  
The Difference ◽  
Lateral Sclerosis

Background: amyotrophic lateral sclerosis (ALS) is a motor neuron degenerative disease with high mortality and few therapies. One of these is riluzole, inspite of uncertainty effectiveness. Objective: the aim of this study was to evaluate the survival rate associated with the use of this medication in the treatment of ALS. Methods: The study was based on a narrative review of the scientific articles that used randomized controled trials with riluzole for ALS. We selected articles published in english during the period of January 1th, 2000 to December 31th, 2020. The MeSH terms “amyotrophic lateral sclerosis” or “motor neuron disease” and “riluzole” or “rilutek” were used in Pubmed and Lilacs databases. Studies that used only patients with advanced stage ALS were excluded. The t-Student test between sample means was applied to determine the significance of the difference between the survival time (years) of the riluzole and placebo treatment, for a 95% confidence level. Results: through the search, four articles were obtained (Table 1). Conclusion: Data analysis showed that riluzole is only effective in the first year. From the second onward, it does not exceed the results of the placebo.

scholarly journals Breaking the Binary

2021 ◽  
Vol 9 (2) ◽  
Author(s):  
Lucy Mercer-Mapstone ◽  
Sarah Bajan ◽  
Kasia Banas ◽  
Arthur Morphett ◽  
Kristine McGrath
Keyword(s):  
Minority Group ◽  
First Year ◽  
Sex And Gender ◽  
Biological Sex ◽  
Positive Attitudes ◽  
Student Cohorts ◽  
The Difference ◽  
Students Attitudes ◽  
And Gender ◽  
Partnership Approach

The need to make higher education curricula gender-inclusive is increasingly pressing as student cohorts diversify. We adopted a student-staff partnership approach to design, integrate, and evaluate a module that taught first-year science students the difference between biological sex, gender identity, gender expression, and sexual orientation in the context of genetics concepts at an Australian university. This module aimed to break the binary in misconceptions of both sex and gender, emphasising that both exist on separate spectra. Data triangulation was used to evaluate students’ attitudes towards the module and their learning of module concepts. Students’ attitudes were positive overall, and evaluation of students’ learning indicated that the majority of students understood and retained key concepts, while also identifying common misconceptions. Perhaps the most important finding was that students who identified as belonging to a minority group had significantly more positive attitudes towards the module than non-minority students. This finding supports previous research that has found inclusive curricula have greater benefit for students from minority backgrounds, indicating the importance of making such curriculum enhancements. Our results speak to both the co-creation process and students’ learning outcomes, providing valuable insights for practitioners both within science and beyond.

Studies on the storage of potatoes II. The temperature conditions inside potato clamps

1950 ◽  
Vol 40 (3) ◽  
pp. 199-226 ◽  
Author(s):  
E. M. Crook ◽  
D. J. Watson
Keyword(s):  
Air Temperature ◽  
Heat Production ◽  
First Year ◽  
Temperature Conditions ◽  
Mean Temperature ◽  
The Difference ◽  
Made In

Continuous records of the temperature of potatoes stored in clamps were made in 1942–3 (one clamp) and in 1943–4 (three clamps). In the first year, the temperatures at various positions in the clamp coverings were also recorded.The temperature at the middle of the potato heap showed a drift with time similar to that of mean air temperature. Deviations of mean air temperature from smooth trend, lasting for about a week, had no effect on the temperature of the potatoes; longerperiod deviations were reflected in the temperature of the potatoes after a lag of about a week. The difference in weekly mean temperature between potatoes and external air averaged about 1–5° C. in 1943–4. In 1942–3 it was greater, increasing to over 20° C. in April, because bacterial rotting of the potatoes following blight infection increased the rate of heat production and caused the clamp to collapse at the end of April.

Combined hormonal contraception and risk of venous thromboembolism within the first year following pregnancy

2014 ◽  
Vol 112 (07) ◽  
pp. 73-78 ◽  
Author(s):  
Thomas Bergholt ◽  
Anne Nielsen ◽  
Michael J. Paidas ◽  
Ellen Christine L. Løkkegaard ◽  
Jesper Petersen
Keyword(s):  
Venous Thromboembolism ◽  
Hormonal Contraception ◽  
Hormonal Contraceptives ◽  
First Year ◽  
The Difference ◽  
Combined Hormonal Contraception ◽  
One Year ◽  
First Time ◽  
Combined Hormonal Contraceptives

SummaryEstimating the risk of venous thromboembolism (VTE) associated with combined hormonal contraceptives following early terminated pregnancies or birth, a Danish nationwide retrospective cohort observing a one-year follow-up was defined using three unique registries. All Danish women with confirmed pregnancies aged 15–49 during the period of 1995–2009 were included. The main outcomes were relative and absolute risks of first time venous thromboembolism in users as well as non-users of combined hormonal contraceptives. In 985,569 person-years, 598 venous thromboembolisms were recorded. After early terminated pregnancies and births, respectively, 113 and 485 events occurred in 212,552 and 773,017 person-years. After early terminated pregnancies, the crude VTE incidence ratios were similar, and the numbers needed to harm were equal between groups that did or did not use combined hormonal contraceptives throughout the follow-up year. After childbirth, individuals that used combined hormonal contraceptives were more likely than non-users to experience VTE depicted by crude incidence ratios; however, the difference was only significant after 14 weeks. This implied that the numbers needed to harm were lower for those that used compared to those that did not use combined oral contraceptives in the initial 14 weeks postpartum. In conclusion, the use of combined hormonal contraceptives after early terminated pregnancies was not detrimental, but during the puerperal period, they should be used with caution.

Sign in / Sign up

Export Citation Format

Share Document