463 research outputs found

    Intra-seasonal variability of extreme boreal stratospheric polar vortex events and their precursors

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    This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this record.The dynamical variability of the boreal stratospheric polar vortex has been usually analysed considering the extended winter as a whole or only focusing on December, January and February. Yet recent studies have found intra-seasonal differences in the boreal stratospheric dynamics. In this study, the intra-seasonal variability of anomalous wave activity preceding polar vortex extremes in the Northern Hemisphere is examined using ERA-Interim reanalysis data. Weak (WPV) and strong (SPV) polar vortex events are grouped into early, mid- or late winter sub-periods depending on the onset date. Overall, the strongest (weakest) wave- activity anomalies preceding polar vortex extremes are found in mid- (early) winter. Most of WPV (SPV) events in early winter occur under the influence of east (west) phase of the Quasi-Biennial Oscillation 20 (QBO) and an enhancement (inhibition) of wavenumber-1 wave activity (WN1). Mid- and late winter WPV 21 events are preceded by a strong vortex and an enhancement of WN1 and WN2, but the spatial structure of the anomalous wave activity and the phase of the QBO are different. Prior to mid-winter WPVs the enhancement of WN2 is related to the predominance of La Niña and linked to blockings over Siberia. Mid-winter SPV events show a negative phase of the Pacific-North America pattern that inhibits WN1 injected into the stratosphere. This study suggests that dynamical features preceding extreme polar vortex events in mid-winter should not be generalized to other winter sub-periods.This work was supported by the Spanish Ministry of Economy and Competitiveness (grant number CGL2012- 34997). BA is supported by the Natural Environment Research Council (grant number NE/M006123/1). MA acknowledges funding from the NASA ACMAP program

    Short Communication. Embryo yield in llamas synchronized with two different intravaginal progesterone-releasing devices and superovulated with eCG

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    The objectives of this study were to compare the effects of two intravaginal devices (ID) containing the same dose (0.5 g) of progesterone (P4) on subsequent ovarian response, embryo production and circulating P4 concentration profile in llamas (Lama glama) treated with equine chorionic gonadotropin (eCG) for ovarian superstimulation. Female llamas were randomly assigned (n = 10 llamas per group) to one of the following groups and treated (Day 0) with an ID containing 0.5 g of vegetal P4 to synchronize the emergence of a new follicular wave: i) DIB 0.5® and ii) Cronipres M15®. On Day 3 llamas were intramuscularly treated with 1000 IU of eCG. The IDs were removed on Day 7. Llamas were naturally mated (Day 9) and treated with GnRH analogue to induce ovulation. A second mating was allowed 24 h later. Embryos were collected between 7 and 8 days after the first mating. Blood samples were taken every day from Day 0 to Day 7 to measure circulating P4 concentrations. The results indicated that DIB device maintained greater plasma P4 levels as compared to Cronipres until Day 2. However, the mean (± SD) number of corpora lutea and recovered embryos was not affected (p < 0.05) by the type of ID (5.3 ± 2.6 vs 4.2 ± 2.2 and 3.5 ± 2.7 vs 2.6 ± 3.0 for DIB and Cronipres, respectively). In conclusion, both DIB and Cronipres devices can be successfully used to synchronize the emergence of follicular wave prior to a single dose of eCG in superovulation protocol in llamas

    Sexo de la cría según el ovario de la ovulación en llamas (Lama glama) de la Puna argentina

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    The aim of this work was to determine the sex ratio of the offspring born from ovulations of the left or right ovaries in naturally mated llamas. Females (n=188) with the presence of an ovarian follicle ≥7 mm received controlled natural mating (Day 0). Ovulation was confirmed on day 2 by the disappearance of the ovarian follicle (n=146). Then, 104 (71.2%) females diagnosed pregnant by ultrasonography were obtained 40-45 days after mating. The mating and calving date, sex and body weight of the calf at birth were recorded in 92 individuals. The overall sex ratio of the offspring and the sex ratio of the offspring from each ovary were compared using the Chi-square goodness-of-fit test, with the expected ratio being 1:1. Ovulations from both ovaries produced a similar (p=0.14) proportion of calves born and the male: female ratio was similar. However, more male offspring originated from the left ovary than from the right (65.2 vs. 34.8%, respectively; p=0.04), although the percentages of males born originated from ovulations from the left ovary (30/53=56.6%; p=0.33) and right ovary (16/39=41.0%; p=0.26) were not different from the expected ratio (1:1). The length of gestation and live weight at birth were statistically similar between sexes.El objetivo del presente trabajo fue determinar la relación de sexos de las crías nacidas provenientes de ovulaciones de los ovarios izquierdo o derecho en llamas naturalmente apareadas. Hembras (n=188) con presencia de un folículo ovárico ≥7 mm recibieron monta natural controlada (Día 0). Se confirmó la ovulación en el día 2 por la desaparición del folículo ovárico (n=146). Se obtuvieron 104 (71.2%) hembras diagnosticadas preñadas por medio de ultrasonografía a los 40-45 días de la monta. Se registró la fecha de monta y parición, sexo y peso vivo de la cría al nacimiento en 92 llamas. La relación sexo de la cría y la relación de sexo de las crías provenientes de cada ovario fueron comparadas mediante la prueba de Chi cuadrado de bondad de ajuste, siendo la relación esperada de 1:1. Ovulaciones provenientes de ambos ovarios produjeron similar (p=0.14) proporción de crías nacidas y la relación macho: hembra fue similar. Sin embargo, más crías de sexo macho fueron originadas del ovario izquierdo que del derecho (65.2 vs. 34.8%, respectivamente; p=0.04), aunque los porcentajes de machos nacidos originados de ovulaciones del ovario izquierdo (30/53=56.6%; p=0.33) y ovario derecho (16/39=41.0%; p=0.26) no fueron diferentes de la relación esperada (1:1). La duración de la gestación y el peso vivo al nacimiento fueron estadísticamente similares entre sexos

    Is children’s education associated with parental health? Evidence from the Philippines

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    This study examines the association between children’s education and parental health using data from the 2007 Philippine Study on Ageing. It employs a broad, more comprehensive, definition of health to capture the different health dimensions. By employing multiple indicators of health, this study is able to examine whether the influence of children's education is consistent across different health indicators. It also investigates whether parental behavior and receipt of support from children serve as pathways that mediate the relationship between children’s education and parental health. Findings show that older women whose children completed tertiary education have lower odds of reporting IADL or ADL difficulty compared with their counterparts whose children attained below tertiary education. These findings contribute to the growing evidence that education is not only an individual resource; rather it could be a household or family resource that could benefit other family members

    Stimulation of ammonia oxidizer and denitrifier abundances by nitrogen loading: Poor predictability for increased soil N2O emission

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    Unprecedented nitrogen (N) inputs into terrestrial ecosystems have profoundly altered soil N cycling. Ammonia oxidizers and denitrifiers are the main producers of nitrous oxide (N2O), but it remains unclear how ammonia oxidizer and denitrifier abundances will respond to N loading and whether their responses can predict N-induced changes in soil N2O emission. By synthesizing 101 field studies worldwide, we showed that N loading significantly increased ammonia oxidizer abundance by 107% and denitrifier abundance by 45%. The increases in both ammonia oxidizer and denitrifier abundances were primarily explained by N loading form, and more specifically, organic N loading had stronger effects on their abundances than mineral N loading. Nitrogen loading increased soil N2O emission by 261%, whereas there was no clear relationship between changes in soil N2O emission and shifts in ammonia oxidizer and denitrifier abundances. Our field-based results challenge the laboratory-based hypothesis that increased ammonia oxidizer and denitrifier abundances by N loading would directly cause higher soil N2O emission. Instead, key abiotic factors (mean annual precipitation, soil pH, soil C:N ratio, and ecosystem type) explained N-induced changes in soil N2O emission. Altogether, these findings highlight the need for considering the roles of key abiotic factors in regulating soil N transformations under N loading to better understand the microbially mediated soil N2O emission

    A systematic review of the impact of educational programs on factors that affect nurses' post-operative pain management for children

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    Despite extensive research in the international arena into pain and its management, there is, as yet, little research on the topic of pain in children in Saudi Arabia and in the Gulf countries generally. A systematic review was conducted to explore the impact of education programs on factors affecting paediatric nurses’ postoperative pain management practice. This was done in order to advise the creation of an educational program for nurses in Saudi Arabia. Knowledge about pain, attitudes towards pain, beliefs about children’s pain, perceptions of children’s reports of pain, self-efficacy with regard to pain management, and perceptions of barriers to optimal practice were all considered to be relevant factors. The review was restricted to randomized controlled trials and quasi-experimental designs, excluding studies focussed on chronic pain or populations other than solely children. Studies published in English between 2000 and 2016 were identified using CINAHL, MEDLINE, Ovid SP, The Cochrane Library, ProQuest, and Google Scholar databases. Of 499 published studies identified by the search, 14 met the inclusion criteria and were included in the review. There was evidence of educational programs exerting a postive impact on enhancing pediatric nurses’ knowledge of pain and modifing their attitudes towards it, but only limited evidence was available about the impact on nurses’ beliefs and perceptions of children’s reports of pain, nurses’ self-efficacy, or barriers to optimal practice. None of the studies was conducted in Saudi Arabia. Studies were needed to address additional aspects of preparedness for effective postperative pain management. Details of educational programs used as experimental intervention must be included in reports

    The global diabatic circulation of the stratosphere as a metric for the Brewer–Dobson circulation

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    The circulation of the stratosphere, also known as the Brewer–Dobson circulation, transports water vapor and ozone, with implications for radiative forcing and climate. This circulation is typically quantified from model output by calculating the tropical upwelling vertical velocity in the residual circulation framework, and it is estimated from observations by using time series of tropical water vapor to infer a vertical velocity. Recent theory has introduced a method to calculate the strength of the global mean diabatic circulation through isentropes from satellite measurements of long-lived tracers. In this paper, we explore this global diabatic circulation as it relates to the residual circulation vertical velocity, stratospheric water vapor, and ozone at interannual timescales. We use a comprehensive climate model, three reanalysis data products, and satellite ozone data. The different metrics for the circulation have different properties, especially with regards to the vertical autocorrelation. In the model, the different residual circulation metrics agree closely and are well correlated with the global diabatic circulation, except in the lowermost stratosphere. In the reanalysis products, however, there are more differences throughout, indicating the dynamical inconsistencies of these products. The vertical velocity derived from the time series of water vapor in the tropics is significantly correlated with the global diabatic circulation, but this relationship is not as strong as that between the global diabatic circulation and the residual circulation vertical velocity. We find that the global diabatic circulation in the lower to middle stratosphere (up to 500 K) is correlated with the total column ozone in the high latitudes and in the tropics. The upper-level circulation is also correlated with the total column ozone, primarily in the subtropics, and we show that this is due to the correlation of both the circulation and the ozone with upper-level temperatures

    A review and meta-analysis of mitigation measures for nitrous oxide emissions from crop residues

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    Crop residues are of crucial importance to maintain or even increase soil carbon stocks and fertility, and thereby to address the global challenge of climate change mitigation. However, crop residues can also potentially stimulate emissions of the greenhouse gas nitrous oxide (N2_{2}O) from soils. A better understanding of how to mitigate N2_{2}O emissions due to crop residue management while promoting positive effects on soil carbon is needed to reconcile the opposing effects of crop residues on the greenhouse gas balance of agroecosystems. Here, we combine a literature review and a meta-analysis to identify and assess measures for mitigating N2_{2}O emissions due to crop residue application to agricultural fields. Our study shows that crop residue removal, shallow incorporation, incorporation of residues with C:N ratio > 30 and avoiding incorporation of residues from crops terminated at an immature physiological stage, are measures leading to significantly lower N2_{2}O emissions. Other practices such as incorporation timing and interactions with fertilisers are less conclusive. Several of the evaluated N2_{2}O mitigation measures implied negative side-effects on yield, soil organic carbon storage, nitrate leaching and/or ammonia volatilization. We identified additional strategies with potential to reduce crop residue N2_{2}O emissions without strong negative side-effects, which require further research. These are: a) treatment of crop residues before field application, e.g., conversion of residues into biochar or anaerobic digestate, b) co-application with nitrification inhibitors or N-immobilizing materials such as compost with a high C:N ratio, paper waste or sawdust, and c) use of residues obtained from crop mixtures. Our study provides a scientific basis to be developed over the coming years on how to increase the sustainability of agroecosystems though adequate crop residue management
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