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Review of Nitrous Oxide (N2O) Emissions from Motor Vehicles
Nitrous oxide (N2O) is both an ozone depleting gas and a potent greenhouse gas (GHG), having a global warming potential (GWP) value nearly 300 times that of carbon dioxide (CO2). While long known to be a trace by-product of combustion, N2O was not considered a pollutant of concern until the introduction of the three-way catalyst (TWC) on light-duty gasoline vehicles in the 1980s. These precious metal-containing catalysts were found to increase N2O emissions substantially. Through extensive research efforts, the effects of catalyst type, temperature, air/fuel ratio, space velocity, and other factors upon N2O emissions became better understood. Although not well documented, N2O emissions from non-catalyst vehicles probably averaged 5-10 mg/mi (on the standard FTP test), while early generation TWC-equipped vehicles exceeded 100 mg/mi. As emissions control systems evolved to meet increasingly stringent criteria pollutant standards, N2O emissions also decreased. Today’s Tier 3 vehicles are required to meet a U.S. Environmental Protection Agency (EPA) N2O tailpipe standard of 10 mg/mi.
N2O emissions from diesel engines and vehicles became of concern in the 2000s, when catalytic control devices such as diesel particulate filters (DPFs), lean oxides of nitrogen (NOx) traps (LNTs), and selective catalytic reduction (SCR) units were introduced to control PM and NOx. As with gasoline vehicles, N2O emissions from diesel applications are a balance between N2O formation and destruction within these catalytic devices. Modern U.S. light-duty diesel vehicles must comply with the same 10 mg/mi N2O standard that applies to gasoline vehicles; modern heavy-duty diesel (HDD) engines must comply with EPA’s recently established N2O standard of 100 mg/bhp-hr. The total GWP of motor vehicle exhaust is dominated by CO2 emissions, with N2O contributing only 1-2%. Furthermore, the total mass of N2O emissions from mobile sources is declining - largely due to turnover of the light-duty fleet. Consequently, N2O emissions from motor vehicles do not represent a significant contribution to global GHGs.
Journal Article
Empire, migration and identity in the British world
This volume brings together established scholars with a new generation of migration and transnational historians. Their work weaves together the 'new' imperial and the 'new' migration histories, and explores the interplay of migration within and between the local, regional, imperial, and transnational arenas.
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The use of ATR-FTIR to track the degradation of single-use polystyrene cup lids during 24 months of temperate outdoor exposure
A set of unused virgin polystyrene coffee cup lids were distributed in the environment (Sutton Bonington, UK) for a period of 24 months to compare monthly degradation rates across four treatments with variable degrees of exposure to natural UV irradiance (full or reduced exposure) and soil (surface or buried). Analysis of monthly samples (hole-punched discs) from three lids of each treatment via FTIR-ATR indicated that the lids in each treatment displayed varying levels of degradation, ranked as follows: exposure on the ground surface, no shading > exposure on the ground surface, shading> both buried treatments. Principal component analyses (PCAs) and the carbonyl index indicated that photooxidation via sunlight exposure was the primary degradation mechanism for polystyrene under these environmentally relevant conditions. Monthly variations in spectra for each treatment (particularly surface treatments) also indicated that degradation rate was not a continuous process, with a multiple regression establishing correlation between monthly carbonyl index for the first 12 months of the experiment, and both UV irradiance and temperature (p = 0.058). This demonstrated that environmental polystyrene degradation rate was closely related to seasonal cycles in the temperate environment.
Journal Article
Drug shortage management: A qualitative assessment of a collaborative approach
Drug shortages frequently and persistently affect healthcare institutions, posing formidable financial, logistical, and ethical challenges. Despite plentiful evidence characterizing the impact of drug shortages, there is a remarkable dearth of data describing current shortage management practices. Hospitals within the same state or region may not only take different approaches to shortages but may be unaware of shortages proximate facilities are facing. Our goal is to explore how hospitals in Michigan handle drug shortages to assess potential need for comprehensive drug shortage management resources. We conducted semi-structured interviews with diverse stakeholders throughout the state to describe experiences managing drug shortages, approaches to recent shortages, openness to inter-institutional engagement, ideas for a shared resource, and potential obstacles to implementation. To solicit additional feedback on ideas for a shared resource gathered from the interviews, we held focus groups with pharmacists, physicians, ethicists, and community representatives. Among participants representing a heterogeneous sample of institutions, three themes were consistent: (1) numerous drug shortage strategies occurring simultaneously; (2) inadequate resources and lead time to proactively manage shortages; and (3) interest in, but varied attitudes toward, a collaborative approach. These data provide insight to help develop and test a shared drug shortage management resource for enhancing fair allocation of scarce drugs. A shared resource may help institutions adopt accepted best practices and more efficiently access or share finite resources in times of shortage.
Journal Article
Association of cancer-related mortality, age and gonadectomy in golden retriever dogs at a veterinary academic center (1989-2016)
Golden retriever dogs have been reported to have an increased prevalence of cancer compared to other breeds. There is also controversy over the effect spay or neuter status might have on longevity and the risk for developing cancer. The electronic medical records system at an academic center was searched for all dogs who had a necropsy exam from 1989-2016. 9,677 canine necropsy examinations were completed of which 655 were golden retrievers. Age was known for 652 with a median age of death 9.15 years. 424 of the 652 (65.0%) were determined to have died because of cancer. The median age for dying of a cause other than cancer was 6.93 years while those dying of cancer had a median age of 9.83 years (p<0.0001). There was no significant difference in the proportion of intact males and castrated males dying of cancer (p = 0.43) but a greater proportion of spayed females died of cancer compared to intact females (p = 0.001). Intact female dogs had shorter life spans than spayed female dogs (p<0.0001), but there were no differences between intact and castrated males. Intriguingly, being spayed or neutered did not affect the risk of a cancer related death but increasing age did. The most common histologic diagnosis found in golden retrievers dying of cancer was hemangiosarcoma (22.64%) followed by lymphoid neoplasia (18.40%). Overall golden retriever dogs have a substantial risk of cancer related mortality in a referral population and age appears to have a larger effect on cancer related mortality than reproductive status.
Journal Article
Longevity and mortality in cats: A single institution necropsy study of 3108 cases (1989–2019)
Client-owned cats who underwent a post-mortem examination (n = 3,108) at a veterinary medical teaching hospital between 1989 and 2019 were studied to determine longevity and factors affecting mortality. Demographic factors, environmental factors, age, and causes of death were assessed. Sexes included 5.66% intact females, 39.86% spayed females, 6.95% intact males and 47.49% neutered males. 84.2% were mixed breed cats. Age at death was known for 2,974 cases with a median of 9.07 years. Cancer was the most common pathophysiologic cause of death (35.81%) and was identified in 41.3% of cats. When categorized by organ system, mortality was most attributed to multiorgan/systemic (21.72%). Renal histologic abnormalities were noted in 62.84% of cats but was considered the primary cause of death in only 13.06% of cats. Intact female and male cats had significantly shorter lifespans than their spayed or neutered counterparts. FeLV positive status was associated with decreased longevity (P<0.0001) while FIV status was not. This study reports on risk factors associated with mortality and highlights areas of research that may contribute to improved lifespan in cats.
Journal Article
Global importance of methane emissions from drainage ditches and canals
Globally, there are millions of kilometres of drainage ditches which have the potential to emit the powerful greenhouse gas methane (CH 4 ), but these emissions are not reported in budgets of inland waters or drained lands. Here, we synthesise data to show that ditches spanning a global latitudinal gradient and across different land uses emit large quantities of CH 4 to the atmosphere. Area-specific emissions are comparable to those from lakes, streams, reservoirs, and wetlands. While it is generally assumed that drainage negates terrestrial CH 4 emissions, we find that CH 4 emissions from ditches can, on average, offset ∼10% of this reduction. Using global areas of drained land we show that ditches contribute 3.5 Tg CH 4 yr −1 (0.6–10.5 Tg CH 4 yr −1 ); equivalent to 0.2%–3% of global anthropogenic CH 4 emissions. A positive relationship between CH 4 emissions and temperature was found, and emissions were highest from eutrophic ditches. We advocate the inclusion of ditch emissions in national GHG inventories, as neglecting them can lead to incorrect conclusions concerning the impact of drainage-based land management on CH 4 budgets.
Journal Article
Functional Links Between Aβ Toxicity, Endocytic Trafficking, and Alzheimer's Disease Risk Factors in Yeast
Aβ (beta-amyloid peptide) is an important contributor to Alzheimer's disease (AD). We modeled Aβ toxicity in yeast by directing the peptide to the secretory pathway. A genome-wide screen for toxicity modifiers identified the yeast homolog of phosphatidylinositol binding clathrin assembly protein (PICALM) and other endocytic factors connected to AD whose relationship to Aβ was previously unknown. The factors identified in yeast modified Aβ toxicity in glutamatergic neurons of Caenorhabditis elegans and in primary rat cortical neurons. In yeast Aβ impaired the endocytic trafficking of a plasma membrane receptor, which was ameliorated by endocytic pathway factors identified in the yeast screen. Thus, links between Aβ, endocytosis, and human AD risk factors can be ascertained with yeast as a model system.
Journal Article