Fifteen Years of HFC-134a Satellite Observations: Comparisons With SLIMCAT Calculations

The phase out of anthropogenic ozone-depleting substances such as chlorofluorocarbons under the terms of the Montreal Protocol led to the development and worldwide use of hydrofluorocarbons (HFCs) in refrigeration, air conditioning, and as blowing agents and propellants. Consequently, over recent years, the atmospheric abundances of HFCs have dramatically increased. HFCs are powerful greenhouse gases and are now controlled under the terms of the 2016 Kigali Amendment to the Montreal Protocol. HFC-134a is currently the most abundant HFC in the atmosphere, breaking the 100 ppt barrier in 2018, and can be measured in the Earth's atmosphere by the satellite remote-sensing instrument ACE-FTS (Atmospheric Chemistry Experiment-Fourier Transform Spectrometer), which has been measuring since 2004. This work uses the ACE-FTS v4.0 data product to investigate global distributions and trends of HFC-134a. These measurements are compared with a simulation of SLIMCAT, a state-of-the-art three-dimensional chemical transport model, which is constrained by global surface HFC-134a measurements. The agreement between observation and model is good, although in the tropical troposphere ACE-FTS measurements are biased low by up to 10–15 ppt. The overall ACE-FTS global trend of HFC-134a for the altitude range 5.5–24.5 km and 2004–2018 time period is approximately linear with a value of 4.49 ± 0.02 ppt/year, slightly lower than the corresponding SLIMCAT trend of 4.66 ppt/year. Using a simple box model, we also estimate the annual global emissions and burdens of HFC-134a from the model data, indicating that emissions of HFC-134a have increased almost linearly, reaching 236 Gg by 2018

Phosgene in the Upper Troposphere and Lower Stratosphere: A Marker for Product Gas Injection Due to Chlorine‐Containing Very Short Lived Substances

Phosgene in the atmosphere is produced via the degradation of carbon tetrachloride, methyl chloroform, and a number of chlorine‐containing very short lived substances (VSLS). These VSLS are not regulated by the Montreal Protocol even though they contribute to stratospheric ozone depletion. While observations of VSLS can quantify direct stratospheric source gas injection, observations of phosgene in the upper troposphere/lower stratosphere can be used as a marker of product gas injection of chlorine‐containing VSLS. In this work we report upper troposphere/lower stratosphere measurements of phosgene made by the ACE‐FTS (Atmospheric Chemistry Experiment Fourier Transform Spectrometer) instrument and compare with results from the TOMCAT/SLIMCAT three‐dimensional chemical transport model to constrain phosgene trends over the 2004–2016 period. The 13‐year ACE‐FTS time series provides the first observational evidence for an increase in chlorine product gas injection. In 2016, VSLS accounted for 27% of modeled stratospheric phosgene, up from 20% in the mid‐2000s

Satellite observations of stratospheric carbonyl fluoride

The vast majority of emissions of fluorine-containing molecules are anthropogenic in nature, e.g. chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs). These molecules slowly degrade in the atmosphere, leading to the formation of HF, COF2, and COClF, which are the main fluorine-containing species in the stratosphere. Ultimately both COF2 and COClF further degrade to form HF, an almost permanent reservoir of stratospheric fluorine due to its extreme stability. Carbonyl fluoride (COF2) is the second-most abundant stratospheric "inorganic" fluorine reservoir, with main sources being the atmospheric degradation of CFC-12 (CCl2F2), HCFC-22 (CHF2Cl), and CFC-113 (CF2ClCFCl2)

Investigating N₂O produced in the mesosphere - Lower thermosphere and its transport to the middle atmosphere

This paper will describe Atmospheric Chemistry - Experiment Fourier Transform Spectrometer (ACE-FTS) N₂O measurements in the middle atmosphere along with its production mechanisms and long-term variation. Comparisons with model N₂O simulations will also be discussed

CT scanning for diagnosing blunt ureteral and ureteropelvic junction injuries

<p>Abstract</p> <p>Background</p> <p>Blunt ureteral and ureteropelvic (UPJ) injuries are extremely rare and very difficult to diagnose. Many of these injuries are missed by the initial trauma evaluation.</p> <p>Methods</p> <p>Trauma registry data was used to identify all blunt trauma patients with ureteral or UPJ injuries, from 1 April 2001 to 30 November 2006. Demographics, injury information and outcomes were determined. Chart review was then performed to record initial clinical and all CT findings.</p> <p>Results</p> <p>Eight patients had ureteral or UPJ injuries. Subtle findings such as perinephric stranding and hematomas, and low density retroperitoneal fluid were evident on all initial scans, and prompted delayed excretory scans in 7/8 cases. As a result, ureteral and UPJ injuries were diagnosed immediately for these seven patients. These findings were initially missed in the eighth patient because significant associated visceral findings mandated emergency laparotomy. All ureteral and UPJ injuries have completely healed except for the case with the delay in diagnosis.</p> <p>Conclusion</p> <p>Most blunt ureteral and UPJ injuries can be identified if delayed excretory CT scans are performed based on initial CT findings of perinephric stranding and hematomas, or the finding of low density retroperitoneal fluid.</p

Bilateral ureteropelvic disruption following blunt abdominal trauma: Case report

<p>Abstract</p> <p>Background</p> <p>Ureteral injury occurs in less than 1% of blunt abdominal trauma cases, partly because the ureters are relatively well protected in the retroperitoneum. Bilateral ureteral injury is extremely rare, with only 10 previously reported cases. Diagnosis may be delayed if ureteric injury is not suspected, and delay of 36 hours or longer has been observed in more than 50% of patients with ureteric injury following abdominal trauma, leading to increased morbidity.</p> <p>Case presentation</p> <p>A 29-year-old man was involved in a highway motor vehicle collision and was ejected from the front passenger seat even though wearing a seatbelt. He was in a preshock state at the scene of the accident. An intravenous line and left thoracic drain were inserted, and he was transported to our hospital by helicopter. Whole-body, contrast-enhanced computed tomography (CT) scan showed left diaphragmatic disruption, splenic injury, and a grade I injury to the left kidney with a retroperitoneal haematoma. He underwent emergency laparotomy. The left diaphragmatic and splenic injuries were repaired. Although a retroperitoneal haematoma was observed, his renal injury was treated conservatively because the haematoma was not expanding. In the intensive care unit, the patient's haemodynamic state was stable, but there was no urinary output for 9 hours after surgery. Anuresis prompted a review of the abdominal x-ray which had been performed after the contrast-enhanced CT. Leakage of contrast material from the ureteropelvic junctions was detected, and review of the repeat CT scan revealed contrast retention in the perirenal retroperitoneum bilaterally. He underwent cystoscopy and bilateral retrograde pyelography, which showed bilateral complete ureteral disruption, preventing placement of ureteral stents. Diagnostic laparotomy revealed complete disruption of the ureteropelvic junctions bilaterally. Double-J ureteral stents were placed bilaterally and ureteropelvic anastomoses were performed. The patient's postoperative progress was satisfactory and he was discharged on the 23^rdday.</p> <p>Conclusion</p> <p>Diagnosis of ureteral injury was delayed, although delayed phase contrast-enhanced CT and abdominal x-rays performed after CT revealed the diagnosis early. Prompt detection and early repair prevented permanent renal damage and the necessity for nephrectomy.</p

Lactational coumestrol exposure increases ovarian apoptosis in adult rats

This study is the first to examine the increased apoptosis in the adult rat ovary after lactational exposure to coumestrol (COU), a potent phytoestrogen. Lactating dams were gavaged at doses of 0.01, 0.1, 1, and 10 mg/kg COU during the lactation period and the reproductive effects of female pups were investigated in young adults. Rats were sacrificed at postnatal days (PND) 81–84. Ovarian weights were reduced significantly at 0.1 and 1.0 mg/kg COU. The reduction in the ovarian weight occurred in parallel with an increase in the apoptosis at PND 135–140. A marked dose-dependent increase in the expressions of active caspase-3 and -7 was observed in ovarian granulosa cells. Immunostaining for active caspase-3 and the TUNEL staining of apoptotic cells were also increased in ovaries exposed to COU in a dose-dependent manner. These results suggest new sights into the effect of lactational exposure to COU on the female reproductive health

Why Amphibians Are More Sensitive than Mammals to Xenobiotics

Dramatic declines in amphibian populations have been described all over the world since the 1980s. The evidence that the sensitivity to environmental threats is greater in amphibians than in mammals has been generally linked to the observation that amphibians are characterized by a rather permeable skin. Nevertheless, a numerical comparison of data of percutaneous (through the skin) passage between amphibians and mammals is lacking. Therefore, in this investigation we have measured the percutaneous passage of two test molecules (mannitol and antipyrine) and three heavily used herbicides (atrazine, paraquat and glyphosate) in the skin of the frog Rana esculenta (amphibians) and of the pig ear (mammals), by using the same experimental protocol and a simple apparatus which minimizes the edge effect, occurring when the tissue is clamped in the usually used experimental device

Past changes in the vertical distribution of ozone - Part 3: Analysis and interpretation of trends

This is the final version of the article. It first appeared from Copernicus Publications via http://dx.doi.org/10.5194/acp-15-9965-2015Abstract. Trends in the vertical distribution of ozone are reported and compared for a number of new and recently revised data sets. The amount of ozone-depleting compounds in the stratosphere (as measured by equivalent effective stratospheric chlorine – EESC) was maximised in the second half of the 1990s. We examine the periods before and after the peak to see if any change in trend is discernible in the ozone record that might be attributable to a change in the EESC trend, though no attribution is attempted. Prior to 1998, trends in the upper stratosphere (~ 45 km, 4 hPa) are found to be −5 to −10 % per decade at mid-latitudes and closer to −5 % per decade in the tropics. No trends are found in the mid-stratosphere (28 km, 30 hPa). Negative trends are seen in the lower stratosphere at mid-latitudes in both hemispheres and in the deep tropics. However, it is hard to be categorical about the trends in the lower stratosphere for three reasons: (i) there are fewer measurements, (ii) the data quality is poorer, and (iii) the measurements in the 1990s are perturbed by aerosols from the Mt Pinatubo eruption in 1991. These findings are similar to those reported previously even though the measurements for the main satellite and ground-based records have been revised. There is no sign of a continued negative trend in the upper stratosphere since 1998: instead there is a hint of an average positive trend of ~ 2 % per decade in mid-latitudes and ~ 3 % per decade in the tropics. The significance of these upward trends is investigated using different assumptions of the independence of the trend estimates found from different data sets. The averaged upward trends are significant if the trends derived from various data sets are assumed to be independent (as in Pawson et al., 2014) but are generally not significant if the trends are not independent. This occurs because many of the underlying measurement records are used in more than one merged data set. At this point it is not possible to say which assumption is best. Including an estimate of the drift of the overall ozone observing system decreases the significance of the trends. The significance will become clearer as (i) more years are added to the observational record, (ii) further improvements are made to the historic ozone record (e.g. through algorithm development), and (iii) the data merging techniques are refined, particularly through a more rigorous treatment of uncertainties. The support of SPARC, IO3C, IGACO-O3 and NDACC was essential to the success of the initiative. Neil Harris thanks the UK Natural Environment Research Council for an Advanced Research Fellowship. Work at the Jet Propulsion Laboratory was performed under contract with the National Aeronautics and Space Administration. Measurements at Lauder are core funded through New Zealand’s Ministry of Business, Innovation and Employment, while those at Woolongong are supported by the Australian Research Council

An Equine Herpesvirus Type 1 (EHV-1) Expressing VP2 and VP5 of Serotype 8 Bluetongue Virus (BTV-8) Induces Protection in a Murine Infection Model

Bluetongue virus (BTV) can infect most species of domestic and wild ruminants causing substantial morbidity and mortality and, consequently, high economic losses. In 2006, an epizootic of BTV serotype 8 (BTV-8) started in northern Europe that caused significant disease in cattle and sheep before comprehensive vaccination was introduced two years later. Here, we evaluate the potential of equine herpesvirus type 1 (EHV-1), an alphaherpesvirus, as a novel vectored DIVA (differentiating infected from vaccinated animals) vaccine expressing VP2 of BTV-8 alone or in combination with VP5. The EHV-1 recombinant viruses stably expressed the transgenes and grew with kinetics that were identical to those of parental virus in vitro. After immunization of mice, a BTV-8-specific neutralizing antibody response was elicited. In a challenge experiment using a lethal dose of BTV-8, 100% of interferon-receptor-deficient (IFNAR−/−) mice vaccinated with the recombinant EHV-1 carrying both VP2 and VP5, but not VP2 alone, survived. VP7 was not included in the vectored vaccines and was successfully used as a DIVA marker. In summary, we show that EHV-1 expressing BTV-8 VP2 and VP5 is capable of eliciting a protective immune response that is distinguishable from that after infection and as such may be an alternative for BTV vaccination strategies in which DIVA compatibility is of importance