Association between surgical quality and long-term survival in lung cancer

OBJECTIVES

There are significant variations in both perioperative and long-term outcomes after lung cancer resection. While perioperative outcomes are often used as comparative measures of quality, they are unreliable, and their association with long-term outcomes remain unclear. In this context, we evaluated whether historical perioperative mortality after lung cancer resection is associated with 5-year survival.

PATIENTS AND METHODS

The National Cancer Database (NCDB) was queried to identify patients diagnosed with non-small cell lung cancer (NSCLC) in 2010-2016 who underwent surgical resection (n = 234200). Hospital-level reliability-adjusted 90-day mortality rate quartiles for 2010-2013 was used as the independent variable to analyze 5-year survival for patients diagnosed in 2014-2016 (n = 85396).

RESULTS

There were 85,396 patients in the 2014-2016 cohort across 1,086 hospitals. Overall observed 90-day mortality rate was 3.2% (SD 17.6%) with 2.6% (SD 16.0%) for the historically best performing quartile vs. 3.9% (SD 19.4%) for the worst performing quartile (p < 0.0001). Patients who underwent resection at hospitals with the best historical mortality rate had significantly better 5-year survival across all stages compared to those treated at hospitals in the worst performing quartile in multivariate Cox regression analysis (all stages - HR 1.21 [95% CI 1.15-1.26]; stage I - HR 1.19 [95% CI 1.12-1.25]; stage II - HR 1.20 [95% CI 1.09-1.32]; stage III - HR 1.36 [95% CI 1.20-1.54]) and Kaplan-Meier survival estimates (all stages - p < 0.0001, stage I - p < 0.0001; stage II - p = 0.0004; stage III - p < 0.0001).

CONCLUSION

With expanded lung cancer screening criteria and likely increase in early-stage detection, profiling performance is paramount to ensuring mortality benefits. We found that episodes surrounding surgical resection may be used to profile long-term outcomes that likely reflect quality across a broader context of care. Evaluating lung cancer care quality using perioperative outcomes may be useful in profiling provider performance and guiding value-based payment policies.

Correlation Between Gaze Behaviors and Social Communication Skills of Young Autistic Children: A Meta-Analysis of Eye-Tracking Studies

This meta-analysis examined correlations between eye-tracking measures of gaze behaviors manifested during dynamic salient social stimuli and behavioral assessment measures of social communication skills of young autistic children. We employed a multilevel model with random effects to perform three separate meta-analyses for correlation between social communication skills and (a) all gaze behaviors, (b) gaze duration, and (c) gaze transition. Subsequently, we performed meta-regression to assess the role of four moderators, including age, continuum of naturalness of stimuli, gaze metric, and area of interest, on correlation effect sizes that were heterogeneous at the population level. A total of 111 correlation coefficients from 17 studies for 1132 young autistic children or children with high-likelihood for autism (Mage range = 6-95 months) were included in this meta-analysis. The correlation effect sizes for all three meta-analyses were significant, supporting the relation between improved gaze behaviors and better social communication skills. In addition, age, gaze metric, and area of interest were significant moderators. This suggests the importance of identifying meaningful gaze behaviors related to social communication skills and the increasingly influential role of gaze behaviors in shaping social communication skills as young autistic children progress through the early childhood stage. The continuum of naturalness of stimuli, however, was revealed to trend towards having a significant moderating effect. Lastly, it is important to note the evidence of potential publication bias. Our findings are discussed in the context of early identification and intervention and unraveling the complex nature of autism.

Parent-to-parent support among parents of children with autism: A review of the literature

LAY ABSTRACT

Parents of autistic children have long reported feelings of isolation and increased stress during and after receiving their child's diagnosis. Increasing global prevalence of autism also calls for increased services and supports to meet the needs of these families, but most parents who live in low-resource settings still report exacerbated barriers. This may indicate the need for diversifying intervention delivery models to increase contextual fit and enhance implementation effects for different populations. For example, many parents have reported parent-to-parent (P2P) model to be a source of emotional support, advocacy, and knowledge related to their child's diagnosis, and practical advice. However, little is known about this topic due to the lack of synthesis of relevant autism literature. To address this gap, we conducted a literature review to gain a deeper understanding of how P2P support is used. We identified 25 studies based on our inclusion and exclusion criteria, which we coded to extract variables such as demographic information of participants, types of P2P, dosage, target outcomes, and social validity. About half of studies focused on providing support groups for parents, and the other half focused on individual matching and mentoring for skill acquisition of parents. Across the included 25 studies, a total of 141 parents participated as parent mentors and 747 parents as parent mentees. We also present implications for future research.

Reported quality indicators and implementation outcomes of community partnership in autism intervention research: A systematic review

There is minimal research on the quality of community partnerships in studies of interventions for autistic children. However, building high quality community engagement in autism intervention research may improve implementation outcomes. This systematic review examined studies that report community partnership in autism intervention research. A total of 135 articles were identified and 11 of these articles were included in the final review. Community partnership data were extracted using indicators from the conceptual framework for assessing research-practice partnerships (RPP; Henrick et al., Henrick et al., Assessing research-practice partnerships: Five dimensions of effectiveness, William T. Grant Foundation, 2017) and implementation outcomes data were extracted using the taxonomy of distinct implementation outcomes (Proctor et al., Administration and Policy in Mental Health and Mental Health Services Research, 38:65-76, 2011). Quality of studies were appraised using JBIs critical appraisal tools (Munn et al., JBI Evidence Synthesis, 18:2127-2133, 2020). RPP indicators and implementation outcomes were variably reported across studies. RPP indicators and implementation outcomes more likely to be reported were related to building trust, cultivating partnership relationships, conducting rigorous research to inform action, acceptability, and feasibility. RPP indicators and implementation outcomes less likely to be reported were related to building capacity to engage in partnership work, sustainability, cost, and penetration. Together, these results may suggest the need for increased sustainability and capacity building efforts in partnerships and increased guidelines for reporting outcomes.

Examining the Efficacy of Culturally Responsive Interventions for Autistic Children and Their Families: A Meta-Analysis

Culturally responsive interventions for autistic children and their families have been developed and implemented to address issues related to limited representation, inequities, and disparities in access to care of minoritized families in research. Currently available reviews are relatively limited in scope or do not synthesize interventions specifically. Therefore, we conducted a meta-analysis to synthesize autism intervention literature that specifically targeted autistic individuals and their family members from minoritized backgrounds, such as immigrant families. We used four databases to identify studies that used culturally responsive interventions with minoritized autistic children and their families. An article was included if it included empirical intervention data using an experimental design. A total of 354 studies were initially screened, and 24 studies were included. Effect sizes of these studies were extracted across two levels (i.e., child and family levels). Data from group design studies were extracted manually, and data from single-case design studies were extracted using a web-based tool. We used design-comparable standardized effect sizes to compare across both designs. The analysis revealed a large, positive, and significant overall effect size across culturally responsive interventions. Specifically, social-communication and mental health outcomes yielded significant effects at the child level. Additionally, parents' mental health and fidelity of strategy implementation also yielded significant results. Our results suggest that culturally responsive interventions yield comparable outcomes to unadapted, original interventions. Future research should examine the distinction between the effect of cultural adaptation and the efficacy of the intervention itself.

Strategies for capacity building in a low-resource setting: Stakeholders' voices

LAY ABSTRACT

Prevalence of autism is increasing all around the globe, but there is still great inequity in accessing evidence-based interventions. Although the field of autism research has made great strides in identifying and establishing evidence-based interventions, dissemination and implementation of these interventions have been reported as inequitable. This inequity is especially highlighted in many low-resource settings, such as Mongolia. As a field, there is still much to be learned about what strategies are used by stakeholders in low-resource settings to build capacity and to mitigate the hardships. To gain a deeper understanding of strategies for capacity building within a low-resource setting, we conducted five focus groups with 30 Mongolian caregivers of children with autism and 15 individual interviews with various professionals who work in Mongolia. These stakeholders reported three main strategies, including (a) partnership, (b) advocacy, and (c) empowerment, which included several strategies and implications on capacity-building practices. Furthermore, the findings from this study may suggest important implications for future intervention research.

The impact on passenger car emissions associated with the promotion and demise of diesel fuel

The promotion and growth in the use of diesel fuel in passenger cars in the UK and Europe over the past two decades led to considerable adverse air quality impacts in urban areas and more widely. In this work, we construct a multi-decade analysis of passenger car emissions in the UK based on real driving emissions data. An important part of the study is the use of extensive vehicle emission remote sensing data covering multiple measurement locations, time periods, environmental conditions and consisting of over 600,000 measurements. These data are used to consider two scenarios: first, that diesel fuel use was not promoted in the early 2000s for climate mitigation reasons, and second, that there was not a dramatic decline in diesel fuel use following the Dieselgate scandal. The strong growth of diesel fuel use coincided with a time when diesel NOx emissions were high and, conversely, the strong decrease of diesel fuel use coincided with a time when diesel vehicle after-treatment systems for NOx control were effective. We estimate that the growth in diesel car use in the UK results in excess NOx emissions of 721 kt over a three decade period; equivalent to over 7 times total annual passenger car NOx emissions and greater than total UK NOx emissions of 681.8 kt in 2021 and with an associated damage cost of £5.875 billion. However, the sharp move away from diesel fuel post-Dieselgate only reduced NOx emissions by 41 kt owing to the effectiveness of modern diesel aftertreatment systems.

Unreported VOC Emissions from Road Transport Including from Electric Vehicles

There are widespread policy assumptions that the phase-out of gasoline and diesel internal combustion engines will over time lead to much reduced emissions of Volatile Organic Compounds (VOCs) from road transport and related fuels. However, the use of real-world emissions measurements from a new mobile air quality monitoring station demonstrated a large underestimation of alcohol-based species in road transport emissions inventories. Scaling of industry sales statistics enabled the discrepancy to be attributed to the use of ancillary solvent products such as screenwash and deicer which are not included in internationally applied vehicle emission methodologies. A fleet average nonfuel nonexhaust VOC emission factor of 58 ± 39 mg veh^-1 km^-1 was calculated for the missing source, which is greater than the total of all VOCs emitted from vehicle exhausts and their associated evaporative fuel losses. These emissions are independent of the vehicle energy/propulsion system and therefore applicable to all road vehicle types including those with battery-electric powertrains. In contrast to predictions, vehicle VOC emissions may actually increase given a predicted growth in total vehicle kilometers driven in a future electrified fleet and will undergo a complete VOC respeciation due to the source change.

Strain-induced dark exciton generation in rippled monolayer MoS2

Recently, it has been revealed that dark excitons play a significant role in optically controlled information processing due to their much longer radiative lifetimes than those of bright ones. For the realizable implementation of the features, it is important to understand and manipulate conditions in which dark excitons could exist. We adopt strain-engineered rippling as a new parameter for the modification of the electronic structure of monolayer MoS₂ and demonstrate the efficient conversion of bright to dark excitons via a first-principles study. For rippled monolayer MoS₂ above a strain of ∼6.8%, we show that the spin order of the conduction band is reversed and the spin forbidden dark exciton then goes below the bright one.

Extensive field evidence for the release of HONO from the photolysis of nitrate aerosols

Particulate nitrate ([Formula: see text]) has long been considered a permanent sink for NO_x (NO and NO₂), removing a gaseous pollutant that is central to air quality and that influences the global self-cleansing capacity of the atmosphere. Evidence is emerging that photolysis of [Formula: see text] can recycle HONO and NO_x back to the gas phase with potentially important implications for tropospheric ozone and OH budgets; however, there are substantial discrepancies in "renoxification" photolysis rate constants. Using aircraft and ground-based HONO observations in the remote Atlantic troposphere, we show evidence for renoxification occurring on mixed marine aerosols with an efficiency that increases with relative humidity and decreases with the concentration of [Formula: see text], thus largely reconciling the very large discrepancies in renoxification photolysis rate constants found across multiple laboratory and field studies. Active release of HONO from aerosol has important implications for atmospheric oxidants such as OH and O₃ in both polluted and clean environments.

Parent-Implemented Interventions via Telepractice in Autism Research: A Review of Social Validity Assessments

Purpose of Review

Parent-implemented autism interventions are considered empirically validated interventions and the use of telepractice in these interventions is reported as effective. However, little is known about the social validity assessments and outcomes of these interventions. The purpose of this review is to explore the current practices of conducting social validity assessment and reporting its outcomes within parent-implemented telepractice autism interventions.

Recent Findings

The 11 reviewed studies included caregivers as participants, telepractice intervention focusing on social communication outcomes of young autistic children, and were published in a peer-reviewed journal within the past five years.

Summary

The researchers in the reviewed articles reported positive outcomes for parent-implemented telepractice autism interventions. Notably, however, information about social validity assessments of the interventions was limited. Researchers are encouraged to evaluate the social validity of interventions using multiple data sources and methods, and report on their findings as they relate to other types of data.

Parent peer coaching program: A cascading intervention for parents of children with autism in Mongolia

LAY ABSTRACT

Parents of children with autism are known to experience severe hardships related to raising their children. These hardships are exacerbated in low-resource settings internationally where there is very little resource for children and their families, including professionals who provide evidence-based treatment. Mongolia was chosen as an example of such low-resource settings in this single-case research, and four parent mentors and five parent peers and their children with autism participated and completed the study. A local parent group, the Autism Association of Mongolia, was actively involved in this study and helped with recruitment, development, adaptation, and implementation of the intervention to increase acceptability and feasibility. In addition, a local bilingual research assistant was also utilized as the purpose of this study was to build capacity of diverse stakeholders of children with autism in Mongolia. The research assistant was trained and coached by the research team on both content (communication teaching strategies and behavior management) and delivery (coaching adults), who then provided coaching to parent mentors via live videoconferencing in Mongolian. Parent mentors then similarly provided coaching to parent peers after observing the interactions with their children with autism. The findings suggest that parents can effectively deliver high-fidelity coaching to disseminate evidence-based treatment in low-resource settings when given proper training and coaching. Further examination on scalability and sustainment of effects is suggested.

Airborne quantification of net methane and carbon dioxide fluxes from European Arctic wetlands in Summer 2019

Arctic wetlands and surrounding ecosystems are both a significant source of methane (CH₄) and a sink of carbon dioxide (CO₂) during summer months. However, precise quantification of this regional CH₄ source and CO₂ sink remains poorly characterized. A research flight using the UK Facility for Airborne Atmospheric Measurement was conducted in July 2019 over an area (approx. 78 000 km²) of mixed peatland and forest in northern Sweden and Finland. Area-averaged fluxes of CH₄ and carbon dioxide were calculated using an aircraft mass balance approach. Net CH₄ fluxes normalized to wetland area ranged between 5.93 ± 1.87 mg m^-2 h^-1 and 4.44 ± 0.64 mg m^-2 h^-1 (largest to smallest) over the region with a meridional gradient across three discrete areas enclosed by the flight survey. From largest to smallest, net CO₂ sinks ranged between -513 ± 74 mg m^-2 h^-1 and -284 ± 89 mg m^-2 h^-1 and result from net uptake of CO₂ by vegetation and soils in the biosphere. A clear gradient of decreasing bulk and area-averaged CH₄ flux was identified from north to south across the study region, correlated with decreasing peat bog land area from north to south identified from CORINE land cover classifications. While N₂O mole fraction was measured, no discernible gradient was measured over the flight track, but a minimum flux threshold using this mass balance method was calculated. Bulk (total area) CH₄ fluxes determined via mass balance were compared with area-weighted upscaled chamber fluxes from the same study area and were found to agree well within measurement uncertainty. The mass balance CH₄ fluxes were found to be significantly higher than the CH₄ fluxes reported by many land-surface process models compiled as part of the Global Carbon Project. There was high variability in both flux distribution and magnitude between the individual models. This further supports previous studies that suggest that land-surface models are currently ill-equipped to accurately capture carbon fluxes inthe region. This article is part of a discussion meeting issue 'Rising methane: is warming feeding warming? (part 2)'.

Isotopic signatures of methane emissions from tropical fires, agriculture and wetlands: the MOYA and ZWAMPS flights

We report methane isotopologue data from aircraft and ground measurements in Africa and South America. Aircraft campaigns sampled strong methane fluxes over tropical papyrus wetlands in the Nile, Congo and Zambezi basins, herbaceous wetlands in Bolivian southern Amazonia, and over fires in African woodland, cropland and savannah grassland. Measured methane δ¹³C_CH4 isotopic signatures were in the range -55 to -49‰ for emissions from equatorial Nile wetlands and agricultural areas, but widely -60 ± 1‰ from Upper Congo and Zambezi wetlands. Very similar δ¹³C_CH4 signatures were measured over the Amazonian wetlands of NE Bolivia (around -59‰) and the overall δ¹³C_CH4 signature from outer tropical wetlands in the southern Upper Congo and Upper Amazon drainage plotted together was -59 ± 2‰. These results were more negative than expected. For African cattle, δ¹³C_CH4 values were around -60 to -50‰. Isotopic ratios in methane emitted by tropical fires depended on the C3 : C4 ratio of the biomass fuel. In smoke from tropical C3 dry forest fires in Senegal, δ¹³C_CH4 values were around -28‰. By contrast, African C4 tropical grass fire δ¹³C_CH4 values were -16 to -12‰. Methane from urban landfills in Zambia and Zimbabwe, which have frequent waste fires, had δ¹³C_CH4 around -37 to -36‰. These new isotopic values help improve isotopic constraints on global methane budget models because atmospheric δ¹³C_CH4 values predicted by global atmospheric models are highly sensitive to the δ¹³C_CH4 isotopic signatures applied to tropical wetland emissions. Field and aircraft campaigns also observed widespread regional smoke pollution over Africa, in both the wet and dry seasons, and large urban pollution plumes. The work highlights the need to understand tropical greenhouse gas emissions in order to meet the goals of the UNFCCC Paris Agreement, and to help reduce air pollution over wide regions of Africa. This article is part of a discussion meeting issue 'Rising methane: is warming feeding warming? (part 2)'.

Challenging Behaviors Online Modules for Parents of Young Children with Disabilities: A Pilot Feasibility Study

Challenging behaviors exhibited by young children negatively affect development and may also prevent children from receiving appropriate education. These behaviors may also hinder positive family interactions and have a significant impact on parents and other family members. Although various parent training approaches exist to increase parents' capacity to address these challenging behaviors, many parents are reportedly not able to access training due to time and resource constraints. To address inequitable dissemination of information, we developed and piloted the use of the Challenging Behavior Online Modules with 10 parents of children with disabilities. In particular, we examined the feasibility of the Challenging Behavior Online Modules for increasing parents' knowledge and use of positive parenting practices with their young children. Parents reported satisfaction with the contents and delivery method of the intervention. Implications and directions for future research are also suggested.

Alphabet strategy for diabetes care: A checklist approach in the time of COVID-19 and beyond

Chronic disease management requires achievement of critical individualised targets to mitigate again long-term morbidity and premature mortality associated with diabetes mellitus. The responsibility for this lies with both the patient and health care professionals. Care plans have been introduced in many healthcare settings to provide a patient-centred approach that is both evidence-based to deliver positive clinical outcomes and allow individualised care. The Alphabet strategy (AS) for diabetes is based around such a care plan and has been evidenced to deliver high clinical standards in both well-resourced and under-resourced settings. Additional patient educational resources include special care plans for those people with diabetes undertaking fasting during Ramadan, Preconception Care, Prevention and Remission of Diabetes. The Strategy and Care Plan has facilitated evidence-based, cost-efficient multifactorial intervention with an improvement in the National Diabetes Audit targets for blood pressure, cholesterol levels and glycated haemoglobin. Many of these attainments were of the standard seen in intensively treated cohorts of key randomized controlled trials in diabetes care such as the Steno-2 and United Kingdom Prospective Diabetes Study. This is despite working in a relatively under-resourced service within the United Kingdom National Health Service. The AS for diabetes care is a useful tool to consider for planning care, education of people with diabetes and healthcare professional. During the time of the coronavirus disease 2019 pandemic the risk factors for the increased mortality observed have to be addressed aggressively. The AS has the potential to help with this aspiration.

Sources of non-methane hydrocarbons in surface air in Delhi, India

Rapid economic growth and development have exacerbated air quality problems across India, driven by many poorly understood pollution sources and understanding their relative importance remains critical to characterising the key drivers of air pollution. A comprehensive suite of measurements of 90 non-methane hydrocarbons (NMHCs) (C₂-C₁₄), including 12 speciated monoterpenes and higher molecular weight monoaromatics, were made at an urban site in Old Delhi during the pre-monsoon (28-May to 05-Jun 2018) and post-monsoon (11 to 27-Oct 2018) seasons using dual-channel gas chromatography (DC-GC-FID) and two-dimensional gas chromatography (GC×GC-FID). Significantly higher mixing ratios of NMHCs were measured during the post-monsoon campaign, with a mean night-time enhancement of around 6. Like with NO_x and CO, strong diurnal profiles were observed for all NMHCs, except isoprene, with very high NMHC mixing ratios between 35-1485 ppbv. The sum of mixing ratios of benzene, toluene, ethylbenzene and xylenes (BTEX) routinely exceeded 100 ppbv at night during the post-monsoon period, with a maximum measured mixing ratio of monoaromatic species of 370 ppbv. The mixing ratio of highly reactive monoterpenes peaked at around 6 ppbv in the post-monsoon campaign and correlated strongly with anthropogenic NMHCs, suggesting a strong non-biogenic source in Delhi. A detailed source apportionment study was conducted which included regression analysis to CO, acetylene and other NMHCs, hierarchical cluster analysis, EPA UNMIX 6.0, principal component analysis/absolute principal component scores (PCA/APCS) and comparison with NMHC ratios (benzene/toluene and i-/n-pentane) in ambient samples to liquid and solid fuels. These analyses suggested the primary source of anthropogenic NMHCs in Delhi was from traffic emissions (petrol and diesel), with average mixing ratio contributions from Unmix and PCA/APCS models of 38% from petrol, 14% from diesel and 32% from liquified petroleum gas (LPG) with a smaller contribution (16%) from solid fuel combustion. Detailed consideration of the underlying meteorology during the campaigns showed that the extreme night-time mixing ratios of NMHCs during the post-monsoon campaign were the result of emissions into a very shallow and stagnant boundary layer. The results of this study suggest that despite widespread open burning in India, traffic-related petrol and diesel emissions remain the key drivers of gas-phase urban air pollution in Delhi.

Key Role of NO3 Radicals in the Production of Isoprene Nitrates and Nitrooxyorganosulfates in Beijing

The formation of isoprene nitrates (IsN) can lead to significant secondary organic aerosol (SOA) production and they can act as reservoirs of atmospheric nitrogen oxides. In this work, we estimate the rate of production of IsN from the reactions of isoprene with OH and NO₃ radicals during the summertime in Beijing. While OH dominates the loss of isoprene during the day, NO₃ plays an increasingly important role in the production of IsN from the early afternoon onwards. Unusually low NO concentrations during the afternoon resulted in NO₃ mixing ratios of ca. 2 pptv at approximately 15:00, which we estimate to account for around a third of the total IsN production in the gas phase. Heterogeneous uptake of IsN produces nitrooxyorganosulfates (NOS). Two mono-nitrated NOS were correlated with particulate sulfate concentrations and appear to be formed from sequential NO₃ and OH oxidation. Di- and tri-nitrated isoprene-related NOS, formed from multiple NO₃ oxidation steps, peaked during the night. This work highlights that NO₃ chemistry can play a key role in driving biogenic-anthropogenic interactive chemistry in Beijing with respect to the formation of IsN during both the day and night.

Children with Autism Spectrum Disorders in Low-Resource Settings: Reported Experiences and Needs of Parents in Mongolia

Although it is well-documented that families of children with autism in developed nations report hardships, few researchers have focused on families who live in less-developed, low-resource settings. Using five focus groups with 30 parents of children with autism in Mongolia, a low- resource setting, the purpose of this study was to provide detailed accounts of their experiences, challenges, and needs. Participants reported severe challenges related to raising their children with autism in their country. Parents shared barriers related to the limited availability of services and support, exacerbated financial burdens, and a lack of enforcement of relevant laws. Parents also shared their perceived needs including more services for their children, more sustainable training and coaching programs for parents, and parents' collective advocacy.

Insights into air pollution chemistry and sulphate formation from nitrous acid (HONO) measurements during haze events in Beijing

Wintertime urban air pollution in many global megacities is characterised by episodic rapid increase in particulate matter concentrations associated with elevated relative humidity - so-called haze episodes, which have become characteristic of cities such as Beijing. Atmospheric chemistry within haze combines gas- and condensed-phase chemical processes, leading to the growth in secondary species such as sulphate aerosols. Here, we integrate observations of reactive gas phase species (HONO, OH, NO_x) and time-resolved aerosol composition, to explore observational constraints on the mechanisms responsible for sulphate growth during the onset of haze events. We show that HONO abundance is dominated by established fast gas-phase photochemistry, but the consideration of the additional formation potentially associated with condensed-phase oxidation of S species by aqueous NO₂ leading to NO₂^- production and hence HONO release, improves agreement between observed and calculated gas-phase HONO levels. This conclusion is highly dependent upon aerosol pH, ionic strength and particularly the parameterisation employed for S(iv) oxidation kinetics, for which an upper limit is derived.

3D Bioprinting-Tunable Small-Diameter Blood Vessels with Biomimetic Biphasic Cell Layers

Blood vessel damage resulting from trauma or diseases presents a serious risk of morbidity and mortality. Although synthetic vascular grafts have been successfully commercialized for clinical use, they are currently only readily available for large-diameter vessels (>6 mm). Small-diameter vessel (<6 mm) replacements, however, still present significant clinical challenges worldwide. The primary objective of this study is to create novel, tunable, small-diameter blood vessels with biomimetic two distinct cell layers [vascular endothelial cell (VEC) and vascular smooth muscle cell (VSMC)] using an advanced coaxial 3D-bioplotter platform. Specifically, the VSMCs were laden in the vessel wall and VECs grew in the lumen to mimic the natural composition of the blood vessel. First, a novel bioink consisting of VSMCs laden in gelatin methacryloyl (GelMA)/polyethylene(glycol)diacrylate/alginate and lyase was designed. This specific design is favorable for nutrient exchange in an ambient environment and simultaneously improves laden cell proliferation in the matrix pore without the space restriction inherent with substance encapsulation. In the vessel wall, the laden VSMCs steadily grew as the alginate was gradually degraded by lyase leaving more space for cell proliferation in matrices. Through computational fluid dynamics simulation, the vessel demonstrated significantly perfusable and mechanical properties under various flow velocities, flow viscosities, and temperature conditions. Moreover, both VSMCs in the scaffold matrix and VECs in the lumen steadily proliferated over time creating a significant two-cell-layered structure. Cell proliferation was confirmed visually through staining the markers of alpha-smooth muscle actin and cluster of differentiation 31, commonly tied to angiogenesis phenomena, in the vessel matrices and lumen, respectively. Furthermore, the results were confirmed quantitatively through gene analysis which suggested good angiogenesis expression in the blood vessels. This study demonstrated that the printed blood vessels with two distinct cell layers of VECs and VSMCs could be potential candidates for clinical small-diameter blood vessel replacement applications.

Dual Resonant Sum Frequency Generations from Two-Dimensional Materials

We propose dual resonant optical sum frequency generation (SFG), where the two most singular resonances could be selected, and report for the monolayer (1L-) WSe₂ when one (ω₁) of two excitation pulses is resonant to A exciton and their sum frequency (ω₁ + ω₂) to D exciton. The dual resonant SFG confirms that, under an irradiation of ω₁ and ω₂ pulses with the same fluence of ∼1.4 × 10¹⁰ W/m², its signal intensity could be enhanced about 20 times higher than the resonant SHG (i.e., 2ω₁ to the D excitonic absorption). Further, the dual resonant SFG intensity of 1L-WSe₂ is found to be 1 order of magnitude higher than the single resonant SFG intensity of 1L-WS₂ under the same condition of two-pulse irradiation. Finally, observations of the dual resonant SFG are thoroughly examined using real-time time-dependent density functional theory (rt-TDDFT), and the relevant nonlinear optical characteristics are scrutinized using the Greenwood-Kubo formalism.

Parent Leadership and Civic Engagement: Suggestions for the Next Individuals With Disabilities Education Act Reauthorization

Although parent involvement is a cornerstone of the Individuals with Disabilities Education Act (IDEA), few individual parents of children with disabilities participate in civic engagement to voice their suggestions for the next IDEA reauthorization. To address this gap, a civic engagement training was conducted with 95 parents of children with disabilities across four states. At the end of the training, participants completed videotaped testimonials voicing their suggestions for the next IDEA reauthorization. Participant suggestions clustered around three themes: expanding IDEA to address specific concerns; adding text to provide specificity and clarity in IDEA; and implementing the current version of IDEA. Implications for research and policy are discussed.

P6561Diagnostic yield of implantable loop recorders: a comparison of arrhythmia nurse specialists versus clinicians

Background

Implantable loop recorders (ILR) are recommended in guidelines to determine symptom-rhythm correlation. Arrhythmia Nurse Specialists (ANS) play a critical role in the assessment of such patients. Their effectiveness at risk stratification for ILR implantation is unknown. The ESC 2018 Syncope guidelines recommend more research in this field.

Aim

To evaluate the diagnostic yield of consecutive ILR implants at a tertiary centre over a 2year period and compare ANS versus Clinicians.

Methods

A retrospective study of all patients undergoing ILR implant between April 2016 and April 2018. Data collected included baseline patient demographics, referral source and management changes made by ILR findings.

Results

305 patients had an ILR; median age was 71yrs (interquartile range 52–81), 55% male. Median follow-up time was 15months. Referrals were from general cardiology (GC) = 98 (32%), electrophysiology (EP) = 105 (34%), and ANS-led syncope clinic = 102 (34%). Indications for ILR implant were syncope = 203 (65.9%), palpitation = 21 (6.9%), pre-syncope = 16 (5.2%), cryptogenic stroke = 35 (11.5%) and others 7 (8.9%) (falls, channelopathies). Of the entire cohort, 102 (34.0%) experienced arrhythmias recorded on the ILR that resulted in a change of management. This included: pacemaker implant = 49 (16.1%), complex-device implant = 7 (2.3%), AF=28 (9.2%), SVT=14 (4.6%), VT=1 (0.3%). Of those with a syncope indication (n=203), findings on ILR altered management in 73patients (36.0%) over a median follow-up of 18months; a pacing indication in this syncope group was present in 44 (21.9%) patients (median time to diagnosis: 2.7 months) with 24 receiving a pacemaker indication within 3 months of ILR insertion. ANS had a higher pacemaker implant rate. Overall, an ILR resulted in a diagnostic yield of 34.1% (n=104). Specialist nurse referral resulted in an overall greater trend towards change of management in 38.2% of patients compared with GC (32.7%) and EP (31.0%) (p=0.593 nurse vs. consultant).

Conclusion

The overall diagnostic yield of ILR insertion was 34% in our study. ANS had a trend towards a greater diagnostic yield compared with clinicians, and significantly more pacemaker indications. Our data suggests that ANS patient selection for ILR insertion are at least comparable to clinicians.

Anomalous Electron Dynamics Induced through the Valley Magnetic Domain: A Pathway to Valleytronic Current Processing

An interplay between an applied strain and the Berry curvature reconstruction in the uniaxially strained monolayer MoS₂ is explored that leads to the unbalanced Berry curvatures centered at K and -K points and, eventually, the valley magnetization under an external electric field. This is shown to explain a recent experimental observation of the valley magnetoelectric effect and develop a novel concept of the valley magnetic domain (VMD), i.e., a real-space homogeneous distribution of the valley magnetization. A realization of VMD guarantees a sufficient number of stable valley-polarized carriers, one of the most essential prerequisites of the valleytronics. Furthermore, we discover the anomalous electron dynamics through the VMD activation and achieve a manipulation of the anomalous transverse current perpendicular to the electric field, directly accessible to the signal processing [for instance, the current modulation under the VMD (i.e., the VMD wall) moving and the terahertz current rectification under the VMD switching]. This suggests a concept of VMD for use in providing new physical insight into the valleytronic functionality and its manipulation as a key ingredient of potential device applications.

Effects of halogens on European air-quality

Halogens (Cl, Br) have a profound influence on stratospheric ozone (O₃). They (Cl, Br and I) have recently also been shown to impact the troposphere, notably by reducing the mixing ratios of O₃ and OH. Their potential for impacting regional air-quality is less well understood. We explore the impact of halogens on regional pollutants (focussing on O₃) with the European grid of the GEOS-Chem model (0.25° × 0.3125°). It has recently been updated to include a representation of halogen chemistry. We focus on the summer of 2015 during the ICOZA campaign at the Weybourne Atmospheric Observatory on the North Sea coast of the UK. Comparisons between these observations together with those from the UK air-quality network show that the model has some skill in representing the mixing ratios/concentration of pollutants during this period. Although the model has some success in simulating the Weybourne ClNO₂ observations, it significantly underestimates ClNO₂ observations reported at inland locations. It also underestimates mixing ratios of IO, OIO, I₂ and BrO, but this may reflect the coastal nature of these observations. Model simulations, with and without halogens, highlight the processes by which halogens can impact O₃. Throughout the domain O₃ mixing ratios are reduced by halogens. In northern Europe this is due to a change in the background O₃ advected into the region, whereas in southern Europe this is due to local chemistry driven by Mediterranean emissions. The proportion of hourly O₃ above 50 nmol mol^-1 in Europe is reduced from 46% to 18% by halogens. ClNO₂ from N₂O₅ uptake onto sea-salt leads to increases in O₃ mixing ratio, but these are smaller than the decreases caused by the bromine and iodine. 12% of ethane and 16% of acetone within the boundary layer is oxidised by Cl. Aerosol response to halogens is complex with small (∼10%) reductions in PM_2.5 in most locations. A lack of observational constraints coupled to large uncertainties in emissions and chemical processing of halogens make these conclusions tentative at best. However, the results here point to the potential for halogen chemistry to influence air quality policy in Europe and other parts of the world.

Correlates of current and heavy smoking among U.S. soldiers returning from combat

Smoking rates are higher in U.S. soldiers than civilians, with combat-experienced soldiers particularly at risk for heavy smoking (≥20 cigarettes/day). While heavy smoking is correlated with mental health symptoms in civilian samples, the extent to which these symptoms, background variables, and unit climate (self-reported assessments of cohesion, organizational support, and leadership) are linked to smoking in at-risk soldiers remains unclear. The present study examines a range of correlates of smoking-related behavior. Cross-sectional, anonymous surveys were collected from 3,380 soldiers following a deployment in 2008-2009. Measures included demographics, combat exposures, unit climate (e.g., unit cohesion, perceived organizational support, leadership), short sleep duration, and behavioral health variables (e.g., posttraumatic stress disorder, depression, anxiety, alcohol misuse, aggression, adverse childhood experiences [ACEs]). Logistic regression modeled the effects of these variables on two outcome variables: daily smoking and heavy smoking. In the current sample, nearly half (47%) of soldiers reported smoking daily, with 35% of all smokers reporting heavy smoking (17% of the entire sample). Daily smoking was associated with demographic (age, gender, education, rank), behavioral health (ACE, alcohol misuse, sleep duration, aggression), and unit characteristics (unit cohesion); only increased combat exposures and aggression were specifically associated with heavy smoking. Interventions focused on the postdeployment period could incorporate messages about alternatives to smoking as a coping strategy while unit interventions or individual counseling addressing aggression could also address smoking as a negative coping strategy. (PsycINFO Database Record

Schottky barrier tuning of the single-layer MoS2 on magnetic metal substrates through vacancy defects and hydrogenation

For the practical device application of the two-dimensional semiconducting MoS₂, it is a critical issue to manipulate the electronic and magnetic properties locally at its contact to the metal electrode. For the tuning of those properties, we have proposed the vacancy-defective 1L-MoS₂ or the hydrogenated 1L-MoS₂ at the metal [Co(0001) or Ni(111)] contacts and performed first-principles electronic structure calculations. By controlling the atomic vacancy defects and the hydrogen coverages, we investigate the Schottky barrier heights and charge and spin transfers at the interface. Our findings provide a physical insight into the practical device design using the two-dimensional MoS₂.

Capacitance-Assisted Sustainable Electrochemical Carbon Dioxide Mineralisation

An electrochemical cell comprising a novel dual-component graphite and Earth-crust abundant metal anode, a hydrogen producing cathode and an aqueous sodium chloride electrolyte was constructed and used for carbon dioxide mineralisation. Under an atmosphere of 5 % carbon dioxide in nitrogen, the cell exhibited both capacitive and oxidative electrochemistry at the anode. The graphite acted as a supercapacitive reagent concentrator, pumping carbon dioxide into aqueous solution as hydrogen carbonate. Simultaneous oxidation of the anodic metal generated cations, which reacted with the hydrogen carbonate to give mineralised carbon dioxide. Whilst conventional electrochemical carbon dioxide reduction requires hydrogen, this cell generates hydrogen at the cathode. Carbon capture can be achieved in a highly sustainable manner using scrap metal within the anode, seawater as the electrolyte, an industrially relevant gas stream and a solar panel as an effective zero-carbon energy source.

Two-dimensional semiconductors ZrNCl and HfNCl: Stability, electric transport, and thermoelectric properties

Searching for novel two-dimensional (2D) semiconducting materials is a challenging issue. We investigate novel 2D semiconductors ZrNCl and HfNCl which would be isolated to single layers from van der Waals layered bulk materials, i.e., ternary transition-metal nitride halides. Their isolations are unquestionably supported through an investigation of their cleavage energies as well as their thermodynamic stability based on the ab initio molecular dynamics and phonon dispersion calculations. Strain engineering is found to be available for both single-layer (1L) ZrNCl and 1L-HfNCl, where a transition from an indirect to direct band gap is attained under a tensile strain. It is also found that 1L-ZrNCl has an excellent electron mobility of about 1.2 × 10³ cm² V⁻¹ s⁻¹, which is significantly higher than that of 1L-MoS₂. Lastly, it is indicated that these systems have good thermoelectric properties, i.e., high Seebeck coefficient and high power factor. With these findings, 1L-ZrNCl and 1L-HfNCl would be novel promising 2D materials for a wide range of optoelectronic and thermoelectric applications.

Evaluating the performance of low cost chemical sensors for air pollution research

Low cost pollution sensors have been widely publicized, in principle offering increased information on the distribution of air pollution and a democratization of air quality measurements to amateur users. We report a laboratory study of commonly-used electrochemical sensors and quantify a number of cross-interferences with other atmospheric chemicals, some of which become significant at typical suburban air pollution concentrations. We highlight that artefact signals from co-sampled pollutants such as CO2 can be greater than the electrochemical sensor signal generated by the measurand. We subsequently tested in ambient air, over a period of three weeks, twenty identical commercial sensor packages alongside standard measurements and report on the degree of agreement between references and sensors. We then explore potential experimental approaches to improve sensor performance, enhancing outputs from qualitative to quantitative, focusing on low cost VOC photoionization sensors. Careful signal handling, for example, was seen to improve limits of detection by one order of magnitude. The quantity, magnitude and complexity of analytical interferences that must be characterised to convert a signal into a quantitative observation, with known uncertainties, make standard individual parameter regression inappropriate. We show that one potential solution to this problem is the application of supervised machine learning approaches such as boosted regression trees and Gaussian processes emulation.

Spatially resolved flux measurements of NOx from London suggest significantly higher emissions than predicted by inventories

To date, direct validation of city-wide emissions inventories for air pollutants has been difficult or impossible. However, recent technological innovations now allow direct measurement of pollutant fluxes from cities, for comparison with emissions inventories, which are themselves commonly used for prediction of current and future air quality and to help guide abatement strategies. Fluxes of NOx were measured using the eddy-covariance technique from an aircraft flying at low altitude over London. The highest fluxes were observed over central London, with lower fluxes measured in suburban areas. A footprint model was used to estimate the spatial area from which the measured emissions occurred. This allowed comparison of the flux measurements to the UK's National Atmospheric Emissions Inventory (NAEI) for NOx, with scaling factors used to account for the actual time of day, day of week and month of year of the measurement. The comparison suggests significant underestimation of NOx emissions in London by the NAEI, mainly due to its under-representation of real world road traffic emissions. A comparison was also carried out with an enhanced version of the inventory using real world driving emission factors and road measurement data taken from the London Atmospheric Emissions Inventory (LAEI). The measurement to inventory agreement was substantially improved using the enhanced version, showing the importance of fully accounting for road traffic, which is the dominant NOx emission source in London. In central London there was still an underestimation by the inventory of 30-40% compared with flux measurements, suggesting significant improvements are still required in the NOx emissions inventory.

Theory and simulation of micropolar fluid dynamics

This paper reviews the fundamentals of micropolar fluid dynamics (MFD), and proposes a numerical scheme integrating Chorin’s projection method and time-centred split method (TCSM) for solving unsteady forms of MFD equations. It has been known that Navier–Stokes equations are incapable of explaining the phenomena at micro and nano scales. On the contrary, MFD can naturally pick up the physical phenomena at micro and nano scales owingto its additional degrees of freedom for gyration. In this study, the analytical and exact solutions of Couette and Hagen–Poiseuille flow are provided. Though this study is limited to the steady flow cases, the unsteady term in the MFD has been taken into account. This present work initiates the development of a general-purpose code of computational micropolar fluid dynamics (CMFD). The discretization scheme in space is demonstrated with nearly second-order accuracy on multiple meshes.

New Method to Determine the Schottky Barrier in Few-Layer Black Phosphorus Metal Contacts

Schottky barrier height and carrier polarity are seminal concepts for a practical device application of the interface between semiconductor and metal electrode. Investigation of those concepts is usually made by a conventional method such as the Schottky-Mott rule, incorporating the metal work function and semiconductor electron affinity, or the Fermi level pinning effect, resulting from the metal-induced gap states. Both manners are, however, basically applied to the bulk semiconductor metal contacts. To explore few-layer black phosphorus metal contacts far from the realm of bulk, we propose a new method to determine the Schottky barrier by scrutinizing the layer-by-layer phosphorus electronic structure from the first-principles calculation combined with the state-of-the-art band unfolding technique. In this study, using the new method, we calculate the Schottky barrier height and determine the contact polarity of Ti, Sc, and Al metal contacts to few-layer (mono-, bi-, tri-, and quadlayer) black phosphorus. This gives a significant physical insight toward the utmost layer-by-layer manipulation of electronic properties of few-layer semiconductor metal contacts.

VOC emission rates over London and South East England obtained by airborne eddy covariance

Volatile organic compounds (VOCs) originate from a variety of sources, and play an intrinsic role in influencing air quality. Some VOCs, including benzene, are carcinogens and so directly affect human health, while others, such as isoprene, are very reactive in the atmosphere and play an important role in the formation of secondary pollutants such as ozone and particles. Here we report spatially-resolved measurements of the surface-to-atmosphere fluxes of VOCs across London and SE England made in 2013 and 2014. High-frequency 3-D wind velocities and VOC volume mixing ratios (made by proton transfer reaction – mass spectrometry) were obtained from a low-flying aircraft and used to calculate fluxes using the technique of eddy covariance. A footprint model was then used to quantify the flux contribution from the ground surface at spatial resolution of 100 m, averaged to 1 km. Measured fluxes of benzene over Greater London showed positive agreement with the UK’s National Atmospheric Emissions Inventory, with the highest fluxes originating from central London. Comparison of MTBE and toluene fluxes suggest that petroleum evaporation is an important emission source of toluene in central London. Outside London, increased isoprene emissions were observed over wooded areas, at rates greater than those predicted by a UK regional application of the European Monitoring and Evaluation Programme model (EMEP4UK). This work demonstrates the applicability of the airborne eddy covariance method to the determination of anthropogenic and biogenic VOC fluxes and the possibility of validating emission inventories through measurements.

Clustering approaches to improve the performance of low cost air pollution sensors

Low cost air pollution sensors have substantial potential for atmospheric research and for the applied control of pollution in the urban environment, including more localized warnings to the public. The current generation of single-chemical gas sensors experience degrees of interference from other co-pollutants and have sensitivity to environmental factors such as temperature, wind speed and supply voltage. There are uncertainties introduced also because of sensor-to-sensor response variability, although this is less well reported. The sensitivity of Metal Oxide Sensors (MOS) to volatile organic compounds (VOCs) changed with relative humidity (RH) by up to a factor of five over the range of 19–90% RH and with an uncertainty in the correction of a factor of two at any given RH. The short-term (second to minute) stabilities of MOS and electrochemical CO sensor responses were reasonable. During more extended use, inter-sensor quantitative comparability was degraded due to unpredictable variability in individual sensor responses (to either measurand or interference or both) drifting over timescales of several hours to days. For timescales longer than a week identical sensors showed slow, often downwards, drifts in their responses which diverged across six CO sensors by up to 30% after two weeks. The measurement derived from the median sensor within clusters of 6, 8 and up to 21 sensors was evaluated against individual sensor performance and external reference values. The clustered approach maintained the cost competitiveness of a sensor device, but the median concentration from the ensemble of sensor signals largely eliminated the randomised hour-to-day response drift seen in individual sensors and excluded the effects of small numbers of poorly performing sensors that drifted significantly over longer time periods. The results demonstrate that for individual sensors to be optimally comparable to one another, and to reference instruments, they would likely require frequent calibration. The use of a cluster median value eliminates unpredictable medium term response changes, and other longer term outlier behaviours, extending the likely period needed between calibration and making a linear interpolation between calibrations more appropriate. Through the use of sensor clusters rather than individual sensors, existing low cost technologies could deliver significantly improved quality of observations.

Recent Internet Use and Associations with Clinical Outcomes among Patients Entering Addiction Treatment Involved in a Web-Delivered Psychosocial Intervention Study

The acceptability and clinical impact of a web-based intervention among patients entering addiction treatment who lack recent internet access are unclear. This secondary analysis of a national multisite treatment study (NIDA Clinical Trials Network-0044) assessed for acceptability and clinical impact of a web-based psychosocial intervention among participants enrolling in community-based, outpatient addiction treatment programs. Participants were randomly assigned to 12 weeks of a web-based therapeutic education system (TES) based on the community reinforcement approach plus contingency management versus treatment as usual (TAU). Demographic and clinical characteristics, and treatment outcomes were compared among participants with recent internet access in the 90 days preceding enrollment (N = 374) and without internet access (N = 133). Primary outcome variables included (1) acceptability of TES (i.e., module completion; acceptability of web-based intervention) and (2) clinical impact (i.e., self-reported abstinence confirmed by urine drug/breath alcohol tests; retention measured as time to dropout). Internet use was common (74 %) and was more likely among younger (18-49 years old) participants and those who completed high school (p < .001). Participants randomized to TES (n = 255) without baseline internet access rated the acceptability of TES modules significantly higher than those with internet access (t = 2.49, df = 218, p = .01). There was a near significant interaction between treatment, baseline abstinence, and internet access on time to dropout (χ ²(1) = 3.8089, p = .051). TES was associated with better retention among participants not abstinent at baseline who had internet access (X ²(1) = 6.69, p = .01). These findings demonstrate high acceptability of this web-based intervention among participants that lacked recent internet access.

The Alphabet Strategy and standards of care in young adults with type 1 diabetes

The Alphabet Strategy is a mnemonic-based approach to assist commitment to important aspects of diabetes care: Advice; Blood pressure lowering; Cholesterol and creatinine control; Diabetes control; Eye examination; Foot examination; and use of Guardian drugs. This strategy reported high standards of care of patients with type 2 diabetes. This study assesses the impact of the Alphabet Strategy on diabetes management in young adults with type 1 diabetes and compared data with those of a recently published multicentre study. Results were analysed using the chi-square test and Student's t-test.

Data were collected retrospectively from 68 patients with type 1 diabetes aged 16—25 years attending the George Eliot Hospital (GEH) adolescent diabetes clinic and who were being managed as per The Alphabet Strategy.

Standards of diabetes care in the GEH clinic were better than those reported in the multicentre study. GEH versus multicentre study: clinic non-attendance 12% vs. 24.6%: mean HbA1C% 8.4 vs. 9.5, p<0.001: screening rates; hypertension 100% vs. 88%, p<0.05; nephropathy 80% vs. 56%, p<0.01; retinopathy 98% in GEH clinic: prevalence of complications; nephropathy 5% vs. 21%, p<0.02; retinopathy 24% vs. 28%, not significant.

In conclusion, we found regular clinic visits and separate adolescent clinics improve glycaemic control. The Alphabet Strategy may be considered an effective approach in monitoring/screening and attaining targets in young adults with type 1 diabetes.

The Alphabet strategy — a tool to achieve clinical trial standards in routine practice?

The Steno-2 study and UKPDS showed that targeted intensified intervention on modifiable cardiovascular risk factors in patients with type 2 diabetes reduces morbidity and mortality. The Alphabet POEM strategy (Practice Of Evidence-based Medicine) assessed the effect of systematic application of the Alphabet Strategy to care of patients with type 2 diabetes. In comparison to the Steno-2 intensive cohort, Alphabet POEM fared similarly with regard to diastolic blood pressure (BP), HbA1C, aspirin and angiotensin-converting enzyme (ACE) inhibitor use, but less well with respect to systolic BP, total cholesterol and use of statins. Alphabet POEM achieved better systolic and diastolic BP than UKPDS but glycaemic control was significantly worse. The standards achieved in the Steno-2 study and UKPDS are in principle, at least, partially achievable in a district general hospital in the UK, but fully achieving them in practice will probably need a radical restructuring, and greater provision of resources.

Rectifying the Optical-Field-Induced Current in Dielectrics: Petahertz Diode

Investigating a theoretical model of the optical-field-induced current in dielectrics driven by strong few-cycle laser pulses, we propose an asymmetric conducting of the current by forming a heterojunction made of two distinct dielectrics with a low hole mass (m_{h}^{*}≪m_{e}^{*}) and low electron mass (m_{e}^{*}≪m_{h}^{*}), respectively. This proposition introduces the novel concept of a petahertz (10^{15}  Hz) diode to rectify the current in the petahertz domain, which should be a key ingredient for the electric signal manipulation of future light-wave electronics. Further, we suggest the candidate dielectrics for the heterojunction.

A pervasive role for biomass burning in tropical high ozone/low water structures

Air parcels with mixing ratios of high O3 and low H2O (HOLW) are common features in the tropical western Pacific (TWP) mid-troposphere (300-700 hPa). Here, using data collected during aircraft sampling of the TWP in winter 2014, we find strong, positive correlations of O3 with multiple biomass burning tracers in these HOLW structures. Ozone levels in these structures are about a factor of three larger than background. Models, satellite data and aircraft observations are used to show fires in tropical Africa and Southeast Asia are the dominant source of high O3 and that low H2O results from large-scale descent within the tropical troposphere. Previous explanations that attribute HOLW structures to transport from the stratosphere or mid-latitude troposphere are inconsistent with our observations. This study suggest a larger role for biomass burning in the radiative forcing of climate in the remote TWP than is commonly appreciated.

On the interpretation of in situ HONO observations via photochemical steady state

A substantial body of recent literature has shown that boundary layer HONO levels are higher than can be explained by simple, established gas-phase chemistry, to an extent that implies that additional HONO sources represent a major, or the dominant, precursor to OH radicals in such environments. This conclusion may be reached by analysis of point observations of (for example) OH, NO and HONO, alongside photochemical parameters; however both NO and HONO have non-negligible atmospheric lifetimes, so these approaches may be problematic if substantial spatial heterogeneity exists. We report a new dataset of HONO, NO_x and HO_x observations recorded at an urban background location, which support the existence of additional HONO sources as determined elsewhere. We qualitatively evaluate the possible impacts of local heterogeneity using a series of idealised numerical model simulations, building upon the work of Lee et al. (J. Geophys. Res., 2013, DOI: 10.1002/2013JD020341). The simulations illustrate the time required for photostationary state approaches to yield accurate results following substantial perturbations in the HO_x/NO_x/NO_y chemistry, and the scope for bias to an inferred HONO source from NO_x and VOC emissions in either a positive or negative sense, depending upon the air mass age following emission. To assess the extent to which these impacts may be present in actual measurements, we present exploratory spatially resolved measurements of HONO and NO_x abundance obtained using a mobile instrumented laboratory. Measurements of the spatial variability of HONO in urban, suburban and rural environments show pronounced changes in abundance are found in proximity to major roads within urban areas, indicating that photo-stationary steady state (PSS) analyses in such areas are likely to be problematic. The measurements also show areas of very homogeneous HONO and NO_x abundance in rural, and some suburban, regions, where the PSS approach is likely to be valid. Implications for future exploration of HONO production mechanisms are discussed.

Atmospheric ethanol in London and the potential impacts of future fuel formulations

There is growing global consumption of non-fossil fuels such as ethanol made from renewable biomass. Previous studies have shown that one of the main air quality disadvantages of using ethanol blended fuels is a significant increase in the production of acetaldehyde, an unregulated and toxic pollutant. Most studies on the impacts of ethanol blended gasoline have been carried out in the US and Brazil, with much less focus on the UK and Europe. We report time resolved measurements of ethanol in London during the winter and summer of 2012. In both seasons the mean mixing ratio of ethanol was around 5 ppb, with maximum values over 30 ppb, making ethanol currently the most abundant VOC in London air. We identify a road transport related source, with ‘rush-hour’ peaks observed. Ethanol is strongly correlated with other road transport-related emissions, such as small aromatics and light alkanes, and has no relationship to summer biogenic emissions. To determine the impact of road transport-related ethanol emission on secondary species (i.e. acetaldehyde and ozone), we use both a chemically detailed box model (incorporating the Master Chemical Mechanism, MCM) and a global and nested regional scale chemical transport model (GEOS-Chem), on various processing time scales. Using the MCM model, only 16% of the modelled acetaldehyde was formed from ethanol oxidation. However, the model significantly underpredicts the total levels of acetaldehyde, indicating a missing primary emission source, that appears to be traffic-related. Further support for a primary emission source comes from the regional scale model simulations, where the observed concentrations of ethanol and acetaldehyde can only be reconciled with the inclusion of large primary emissions. Although only constrained by one set of observations, the regional modelling suggests a European ethanol source similar in magnitude to that of ethane (∼60 Gg per year) and greater than that of acetaldehyde (∼10 Gg per year). The increased concentrations of ethanol and acetaldehyde from primary emissions impacts both radical and NO_x cycling over Europe, resulting in significant regional impacts on NO_y speciation and O₃ concentrations, with potential changes to human exposure to air pollutants.

Enhanced light absorption by mixed source black and brown carbon particles in UK winter

Black carbon (BC) and light-absorbing organic carbon (brown carbon, BrC) play key roles in warming the atmosphere, but the magnitude of their effects remains highly uncertain. Theoretical modelling and laboratory experiments demonstrate that coatings on BC can enhance BC's light absorption, therefore many climate models simply assume enhanced BC absorption by a factor of ∼1.5. However, recent field observations show negligible absorption enhancement, implying models may overestimate BC's warming. Here we report direct evidence of substantial field-measured BC absorption enhancement, with the magnitude strongly depending on BC coating amount. Increases in BC coating result from a combination of changing sources and photochemical aging processes. When the influence of BrC is accounted for, observationally constrained model calculations of the BC absorption enhancement can be reconciled with the observations. We conclude that the influence of coatings on BC absorption should be treated as a source and regionally specific parameter in climate models.