136 research outputs found

    The impact of new water vapor spectroscopy on satellite retrievals

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    Water vapor, arguably the most important trace gas constituent of Earth atmospheric physics, is also both a retrieval goal and a hindrance in the retrievals of other trace gases from nadir-measuring satellite spectrometers. This is because the atmospherically-attenuated solar spectrum in the visible and shortwave infrared is littered with water vapor bands. The recent plethora of water vapor spectroscopy databases in this spectral region has prompted us to study their utility in satellite retrievals. We consider water vapor spectroscopy compiled from four sources including new spectroscopy due to University College London and Imperial College London. Radiative transfer models of satellite measurements, in combination with accurate retrieval techniques, are quite sensitive to the accuracy and completeness of the water vapor spectroscopy. Notwithstanding the high degree of variability of a number of different factors in satellite measurements we show that retrievals are sensitive to database differences which suggests that our knowledge of water vapor spectroscopy is not as yet complete. In addition, new laboratory measurements indicate that the role of both the far-line wings of water vapor and the cumulative effect of many weak lines each have an important role to play in forming the so-called continuum

    D-region ion–neutral coupled chemistry (Sodankylä Ion Chemistry, SIC) within the Whole Atmosphere Community Climate Model (WACCM 4) – WACCM-SIC and WACCM-rSIC

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    This study presents a new ion–neutral chemical model coupled into the Whole Atmosphere Community Climate Model (WACCM). The ionospheric D-region (altitudes ∼  50–90 km) chemistry is based on the Sodankylä Ion Chemistry (SIC) model, a one-dimensional model containing 307 ion–neutral and ion recombination, 16 photodissociation and 7 photoionization reactions of neutral species, positive and negative ions, and electrons. The SIC mechanism was reduced using the simulation error minimization connectivity method (SEM-CM) to produce a reaction scheme of 181 ion–molecule reactions of 181 ion–molecule reactions of 27 positive and 18 negative ions. This scheme describes the concentration profiles at altitudes between 20 km and 120 km of a set of major neutral species (HNO3, O3, H2O2, NO, NO2, HO2, OH, N2O5) and ions (O2+, O4+, NO+, NO+(H2O), O2+(H2O), H+(H2O), H+(H2O)2, H+(H2O)3, H+(H2O)4, O3−, NO2−, O−, O2, OH−, O2−(H2O), O2−(H2O)2, O4−, CO3−, CO3−(H2O), CO4−, HCO3−, NO2−, NO3−, NO3−(H2O), NO3−(H2O)2, NO3−(HNO3), NO3−(HNO3)2, Cl−, ClO−), which agree with the full SIC mechanism within a 5 % tolerance. Four 3-D model simulations were then performed, using the impact of the January 2005 solar proton event (SPE) on D-region HOx and NOx chemistry as a test case of four different model versions: the standard WACCM (no negative ions and a very limited set of positive ions); WACCM-SIC (standard WACCM with the full SIC chemistry of positive and negative ions); WACCM-D (standard WACCM with a heuristic reduction of the SIC chemistry, recently used to examine HNO3 formation following an SPE); and WACCM-rSIC (standard WACCM with a reduction of SIC chemistry using the SEM-CM method). The standard WACCM misses the HNO3 enhancement during the SPE, while the full and reduced model versions predict significant NOx, HOx and HNO3 enhancements in the mesosphere during solar proton events. The SEM-CM reduction also identifies the important ion–molecule reactions that affect the partitioning of odd nitrogen (NOx), odd hydrogen (HOx) and O3 in the stratosphere and mesosphere

    Methods for specifying the target difference in a randomised controlled trial : the Difference ELicitation in TriAls (DELTA) systematic review

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    Peer reviewedPublisher PD

    Specialist antenatal clinics for women at high risk of preterm birth: a systematic review of qualitative and quantitative research

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    Background Preterm birth (PTB) is the leading cause of perinatal morbidity and mortality. Women with previous prenatal loss are at higher risk of preterm birth. A specialist antenatal clinic is considered as one approach to improve maternity and pregnancy outcomes. Methods A systematic review of quantitative, qualitative and mixed method studies conducted on women at high risk of preterm birth (PTB). The review primary outcomes were to report on the specialist antenatal clinics effect in preventing or reducing preterm birth, perinatal mortality and morbidity and women’s perceptions and experiences of a specialist clinic whether compared or not compared with standard antenatal care. Other secondary maternal, infant and economic outcomes were also determined. A comprehensive search strategy was carried out in English within electronic databases as far back as 1980. The reviewers selected studies, assessed the quality, and extracted data independently. Results were summarized and tabulated. Results Eleven studies fully met the review inclusion criteria, ten were quantitative design studies and only one was a qualitative design study. No mixed method design study was included in the review. All were published after 1989, seven were conducted in the USA and four in the UK. Results from five good to low quality randomised controlled trials (RCTs), all conducted before 1990, did not illustrate the efficacy of the clinic in reducing preterm birth. Whereas results from more recent low quality cohort studies showed some positive neonatal outcomes. Themes from one good quality qualitative study reflected on the emotional and psychological need to reduce anxiety and stress of women referred to such a clinic. Women expressed their negative emotional responses at being labelled as high risk and positive responses to being assessed and treated in the clinic. Women also reported that their partners were struggling to cope emotionally. Conclusions Findings from this review were mixed. Evidence from cohort studies indicated a specialist clinic may be a means of predicting or preventing preterm birth. Testing this in a randomised controlled trial is desirable, though may be hard to achieve due to the growing focus of such clinics on managing women at high risk of preterm birth. Ongoing research has to recognize women’s experiences and perceptions of such a clinic. Further clarification of the optimal referral route and a clear and standardized management and cost economic evaluation plan are also required. Fathers support and experience of PTB clinics should also be included in further research

    The spatial extent of tephra deposition and environmental impacts from the 1912 Novarupta eruption

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    The eruption of Novarupta within the Katmai Volcanic Cluster, south-west Alaska, in June 1912 was the most voluminous eruption of the twentieth century but the distal distribution of tephra deposition is inadequately quantified. We present new syntheses of published tephrostratigraphic studies and a large quantity of previously un-investigated historical records. For the first time, we apply a geostatistical technique, indicator kriging, to integrate and interpolate such data. Our results show evidence for tephra deposition across much of Alaska, Yukon, the northern Pacific, western British Columbia and northwestern Washington. The most distal tephra deposition was observed around 2,500 km downwind from the volcano. Associated with tephra deposition are many accounts of acid deposition and consequent impacts on vegetation and human health. Kriging offers several advantages as a means to integrate and present such data. Future eruptions of a scale similar to the 1912 event have the potential to cause widespread disruption. Historical records of tephra deposition extend far beyond the limit of deposition constrained by tephrostratigraphic records. The distal portion of tephra fallout deposits is rarely adequately mapped by tephrostratigraphy alone; contemporaneous reports of fallout can provide important constraints on the extent of impacts following large explosive eruptions

    New thermodynamic data for CoTiO3, NiTiO3 and CoCO3 based on low-temperature calorimetric measurements

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    The low-temperature heat capacities of nickel titanate (NiTiO3), cobalt titanate (CoTiO3), and cobalt carbonate (CoCO3) were measured between 2 and 300 K, and thermochemical functions were derived from the results. Our new data show previously unknown low-temperature lambda-shaped heat capacity anomalies peaking at 37 K for CoTiO3 and 26 K for NiTiO3. From our data we calculate standard molar entropies (298.15 K) for NiTiO3 of 90.9 ± 0.7 J mol-1 K-1 and for CoTiO3 of 94.4 ± 0.8 J mol-1 K-1. For CoCO3, we find only a small broad heat capacity anomaly, peaking at about 31 K. From our data, we suggest a new standard entropy (298.15 K) for CoCO3 of 88.9 ± 0.7 J mol-1 K-1

    Lung Adenocarcinoma of Never Smokers and Smokers Harbor Differential Regions of Genetic Alteration and Exhibit Different Levels of Genomic Instability

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    Recent evidence suggests that the observed clinical distinctions between lung tumors in smokers and never smokers (NS) extend beyond specific gene mutations, such as EGFR, EML4-ALK, and KRAS, some of which have been translated into targeted therapies. However, the molecular alterations identified thus far cannot explain all of the clinical and biological disparities observed in lung tumors of NS and smokers. To this end, we performed an unbiased genome-wide, comparative study to identify novel genomic aberrations that differ between smokers and NS

    The ACER pollen and charcoal database: A global resource to document vegetation and fire response to abrupt climate changes during the last glacial period

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    This is the final version of the article. Available from Copernicus Publications via the DOI in this record.Quaternary records provide an opportunity to examine the nature of the vegetation and fire responses to rapid past climate changes comparable in velocity and magnitude to those expected in the 21st-century. The best documented examples of rapid climate change in the past are the warming events associated with the Dansgaard-Oeschger (D-O) cycles during the last glacial period, which were sufficiently large to have had a potential feedback through changes in albedo and greenhouse gas emissions on climate. Previous reconstructions of vegetation and fire changes during the D-O cycles used independently constructed age models, making it difficult to compare the changes between different sites and regions. Here, we present the ACER (Abrupt Climate Changes and Environmental Responses) global database, which includes 93 pollen records from the last glacial period (73-15ka) with a temporal resolution better than 1000years, 32 of which also provide charcoal records. A harmonized and consistent chronology based on radiometric dating (14C, 234U/230Th, optically stimulated luminescence (OSL), 40Ar/39Ar-dated tephra layers) has been constructed for 86 of these records, although in some cases additional information was derived using common control points based on event stratigraphy. The ACER database compiles metadata including geospatial and dating information, pollen and charcoal counts, and pollen percentages of the characteristic biomes and is archived in Microsoft Access™ at https://doi.org/10.1594/PANGAEA.870867.The members of the ACER project wish to thank the QUEST-DESIRE (UK and France) bilateral project, the INQUA International Focus Group ACER and the INTIMATE-COST action for funding a suite of workshops to compile the ACER pollen and charcoal database and the workshop on ACER chronology that allow setting the basis for harmonizing the chronologies. Josué M. Polanco-Martinez was funded by a Basque Government postdoctoral fellowship (POS_2015_1_0006) and Sandy P. Harrison by the ERC Advanced Grant GC2.0: unlocking the past for a clearer future

    Cardiovascular and metabolic influences of fetal smoke exposure

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    Many epidemiological studies showed associations of low birth weight with cardiovascular disease, type 2 diabetes and obesity. The associations seem to be consistent and stronger among subjects with a postnatal catch up growth. It has been suggested that developmental changes in response to adverse fetal exposures might lead to changes in the fetal anatomy and physiology. These adaptations may be beneficial for short term, but may lead to common diseases in adulthood. Maternal smoking during pregnancy is one of the most important adverse fetal exposures in Western countries, and is known to be associated with a 150–200 g lower birth weight. An accumulating body of evidence suggests that maternal smoking during pregnancy might be involved in pathways leading to both low birth weight and common diseases, including cardiovascular disease, type 2 diabetes and obesity, in adulthood. In this review, we discuss epidemiological studies focused on the associations of maternal smoking with fetal growth and development and cardiovascular and metabolic disease in later life. We also discuss potential biological mechanisms, and challenges for future epidemiological studies
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