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Background: Approximately 3 to 4 billion people worldwide are exposed to household air pollution, which has been associated with increased blood pressure (BP) in pregnant women in some studies. Methods: We recruited 3195 pregnant women in Guatemala, India, Peru, and Rwanda and randomly assigned them to intervention or control groups. The intervention group received a gas stove and fuel during pregnancy, while the controls continued cooking with solid fuels. We measured BP and personal exposure to PM 2.5 , black carbon and carbon monoxide 3× during gestation. We conducted an intention-to-treat and exposure-response analysis to determine if household air pollution exposure was associated with increased gestational BP. Results: Median 24-hour PM 2.5 dropped from 84 to 24 μg/m 3 after the intervention; black carbon and carbon monoxide decreased similarly. Intention-to-treat analyses showed an increase in systolic BP and diastolic BP in both arms during gestation, as expected, but the increase was greater in intervention group for both systolic BP (0.69 mm Hg [0.03–1.35]; P =0.04) and diastolic BP (0.62 mm Hg [0.05–1.19]; P =0.03). The exposure-response analyses suggested that higher exposures to household air pollution were associated with moderately higher systolic BP and diastolic BP; however, none of these associations reached conventional statistical significance. Conclusions: In intention-to-treat, we found higher gestational BP in the intervention group compared with controls, contrary to expected. In exposure-response analyses, we found a slight increase in BP with higher exposure, but it was not statistically significant. Overall, an intervention with gas stoves did not markedly affect gestational BP.

RATIONALE: Pneumonia is the leading cause of death in children worldwide. Identifying and appropriately managing severe pneumonia in a timely manner improves outcomes. Little is known about the readiness of healthcare facilities to manage severe pediatric pneumonia in low-resource settings. OBJECTIVES: As part of the Household Air Pollution Intervention Network (HAPIN) trial, we sought to identify healthcare facilities that were adequately resourced to manage severe pediatric pneumonia in Jalapa, Guatemala (J-GUA); Puno, Peru (P-PER); Kayonza, Rwanda (K-RWA); and Tamil Nadu, India (T-IND). We conducted a facility-based survey of available infrastructure, staff, equipment, and medical consumables. Facilities were georeferenced and a road network analysis was performed. MEASUREMENTS AND MAIN RESULTS: Of the 350 healthcare facilities surveyed, 13% had adequate resources to manage severe pneumonia, 37% had pulse oximeters, and 44% had supplemental oxygen. Mean (±SD) travel time to an adequately-resourced facility was 41±19 minutes in J-GUA, 99±64 minutes in P-PER, 40±19 minutes in K-RWA, and 31±19 minutes in T-IND. Expanding pulse oximetry coverage to all facilities reduced travel time by 44% in J-GUA, 29% in P-PER, 29% in K-RWA, and 11% in T-IND (all p

Correlation filter (CF) based trackers have recently drawn great attention in visual tracking community due to their impressive performance, and computational efficiency on benchmark datasets. However, the performance of most existing trackers using correlation filter is hampered by two aspects: i) Included background information in the selected rectangular target patch is considered as part of the target, and they are treated as important as the real target in training new filter model, it causes the filter easily drift when target shape changes dramatically. ii) Existing filters use a moving average operation with an empirical weight to update the filter model in each frame, such per frame adaptation constantly introduces new information of the target patch, but never consider the consistence of the historical information, and the newly obtained one, further increases the risk of drifting. This paper presents a new framework including saliency map, and a novel CF regression model. We reformulate the original optimization problem, and provide a closed form solution for multidimensional features which is solved efficiently using alternating direction method of multipliers (ADMM), and accelerated using Sherman-Morrison lemma, our algorithm as a new framework can be easily integrated into CF base trackers to boost their tracking performance. We perform comprehensive experiments on five benchmarks: OTB-2015, VOT2016, VOT2018, UAV123, and TempleColor-128. Results show that the proposed method performs favorably against lots of state-of-the-art methods with a speed close to real-time. Our method with deep features performs much better on all 5 datasets.

The characteristics of the T/S structures, water mass exchange and deep circulation in the Andaman Sea are investigated based on the simulation from a high-resolution general circulation model (MITgcm). The results show that, below 1 000 m, the water mass is saltier, warmer and more homogeneous in the Andaman Sea than that in the Bay of Bengal, attributing to the strong vertical mixing at the depth of ∼1 800 m. The water mass exchange between the Andaman Sea and the Bay of Bengal goes through three major channels, which manifests itself as follows: the northern channel (Preparis Channel) is the main passage of water mass transport from the Bay of Bengal to the Andaman Sea, whereas the Middle Channel (the south of Andaman Islands and the north of Nicobar Islands) has an opposite transport; the southern channel (Great Channel) features with a four-layer water exchange which results in the least net transport among the three channels; all the transports through the three channels have an intra-annual variation with a period of half a year. At 1 000-m depth, the entire Andaman Sea is occupied by a cyclonic circulation in January and July while by an anticyclonic one in April and October. The semiannual cycle found in both the deep circulation and water mass exchange is likely associated with the downwelling eastward-propagating Kelvin waves induced by the semiannual westerly component in the equatorial Indian Ocean during intermonsoon seasons.

Background: Ambient fine particulate matter [PM ≤2.5μm in aerodynamic diameter (PM2.5)] is a major health risk for children, particularly in South Asia, which currently experiences the highest PM2.5 levels globally. Nevertheless, there is comparatively little epidemiological evidence from this region to quantify the effects of PM2.5 on child survival. Objectives: We estimated the association between PM2.5 exposure and child survival in India. Methods: We constructed a large, retrospective, and nationally representative cohort of children

This paper studies the hybrid event-triggered tracking control based on an unmanned autonomous helicopter (UAH) and an unmanned ground vehicle (UGV) under unmeasurable states, transmission delay, external disturbance, and deception attacks. By designing a switching condition, a hybrid event-triggered scheme (ETS) is proposed to realize an elegant trade-off between less data transmissions and control performance. Then, based on the designs of the observer and tracking controller, an augmented closed-loop system is established, and a sufficient condition on uniform ultimate boundedness is presented. Moreover, a co-design method of the hybrid ETS, observer, and controller is obtained via linear matrix inequalities (LMIs), which is further extended by utilizing an improved adaptive hybrid ETS. Finally, some simulation and comparisons are exploited to illustrate the proposed method.

This work presents a dynamic event-triggered sliding mode controller to solve the problem on cooperative formation flight for unmanned aerial vehicles (UAVs) under outside disturbances and communication delay. Initially, a second-order kinematic model for each UAV is established, and the leader-follower framework is adopted to realize the desired formation flight. Second, an effective design of disturbance observer is proposed based on that the disturbance in the UAV is generated by an external nonlinear system. Third, a new dynamic event-triggered mechanism (DETM) is presented and the triggering threshold is adjusted by an exogenous system, which can help reduce data transmissions and maintain control performance more efficiently. Then, a distributed dynamic event-triggered sliding mode control strategy is proposed for the UAV system, and two sufficient conditions on exponential stability of the overall closed-loop system are derived. Furthermore, the controller gain, observer gain, and triggering parameter can be obtained by solving the derived linear matrix inequalities (LMIs). Finally, a simulated example is exploited to illustrate the obtained results.

The preconception period is a critical window for gametogenesis, therefore preconception exposure to air pollutants may have long-term effects on children. We systematically reviewed epidemiological evidence concerning the effects of preconception ambient air pollution exposure on children's health outcomes and identified research gaps for future investigations. We searched PubMed and Web of Science from journal inception up to October 2022 based on an established protocol (PROSPERO: CRD42022277608). We then identified 162 articles based on searching strategy, 22 of which met the inclusion criteria. Studies covered a wide range of health outcomes including birth defects, preterm birth, birthweight, respiratory outcomes, and developmental outcomes. Findings suggested that exposure to outdoor air pollutants during maternal preconception period were associated with various health outcomes, of which birth defects has the most consistent findings. A meta-analysis revealed that during 3-month preconception period, a 10 μg/m

Computer vision plays a key role in measuring the relative posture and position between spacecrafts, especially in various close-range space tasks. As one of the essential steps for computer vision, camera calibration is important for obtaining precise three-dimensional contours of a space target. The focal length of on-orbit zoom cameras constantly changes. Thus, it is practical to calibrate the focal length rather than other intrinsic camera parameters. However, traditional calibration targets, such as checkerboards, cannot be used to calibrate a space camera in orbit. To address this problem, we propose a two-step process for focal length calibration. In the first step, the initial estimate of the camera focal length was generated with vanishing points obtained from the solar panels of satellites. In the second step, the initial solution was optimized by the particle swarm optimization algorithm. The results of the simulations and laboratory experiments confirmed the accuracy, flexibility, and good antinoise interference performance of the proposed method. Thus, the proposed method has practical significance for space tasks, such as space rendezvous-docking and on-orbit maintenance.

Polarization-sensitive photodetectors based on anisotropic semiconductors sense both the intensity and polarization state information without extra optical components. Here, a self-powered organic photodetector (OPD) composed of intrinsically stretchable polymer donor PNTB6-Cl and non-fullerene acceptor Y6 is reported. The PNTB6-Cl:Y6 photoactive film accommodates a remarkable 100% strain without fracture, exhibiting a high optical anisotropy of 1.8 after strain alignment. The resulting OPD not only shows an impressive faint-light detection capability (high spectral responsivity of 0.45 A W

Background Household air pollution adversely affects human health and the environment, yet more than 40% of the world still depends on solid cooking fuels. The House Air Pollution Intervention Network (HAPIN) randomized controlled trial is assessing the health effects of a liquefied petroleum gas (LPG) stove and 18-month supply of free fuel in 3,200 households in rural Guatemala, India, Peru, and Rwanda. Aims We conducted formative research in Guatemala to create visual messages that support the sustained, exclusive use of LPG in HAPIN intervention households. Method We conducted ethnographic research, including direct observation ( n = 36), in-depth ( n = 18), and semistructured ( n = 6) interviews, and 24 focus group discussions ( n = 96) to understand participants’ experience with LPG. Sixty participants were selected from a pilot study of LPG stove and 2-months of free fuel to assess the acceptability and use of LPG. Emergent themes were used to create visual messages based on observations and interviews in 40 households; messages were tested and revised in focus group discussions with 20 households. Results We identified 50 codes related to household air pollution and stoves; these were reduced into 24 themes relevant to LPG stoves, prioritizing 12 for calendars. Messages addressed fear and reluctance to use LPG; preference of wood stoves for cooking traditional foods; sustainability and accessibility of fuel; association between health outcomes and household air pollution; and the need for inspirational and aspirational messages. Discussion We created a flip chart and calendar illustrating themes to promote exclusive LPG use in HAPIN intervention households.

Calcium looping is a promising technology for CO2 capture, although traditional calcium-based sorbents undergo a rapid loss of capacity after repeated cycles. Improving the toughness of sorbents can be accomplished with the use of stabilizer compounds, but at the cost of sorption performance. Minimizing the stabilizer content whilst maintaining high thermal stability is an effective pathway to solve this bottleneck. Here, a facile MOF-templated synthesis route is for the first time reported to yield highly efficient Al2O3-stabilized, Ca-based sorbents. Cyclic performance experiments and detailed characterization techniques are employed to identify the effects of synthesis factors on the structure-performance relationship of the synthesized CO2 sorbents. Calcium aluminum solid solution and its homogeneous mixture with CaO at the nanoscale provide for high thermal stability. The different CO2 uptake behavior for the synthesized sorbents primarily results from the influence of synthesis factors on the crystallization rates and coordination modes between metal ion and organic ligands. The stabilizer content (i.e. Al2O3) can be as low as 4.44 wt% and yet maintain a favorable thermal stability. Compared to that of the limestone-derived CO2 sorbents, the best MOF-derived sorbent can achieve about 500% times the CO2 sorption capacity after 30 repeated CO2 uptakes and sorbent regenerations.

Background There are only a few studies on sex hormones in females of different ages suffering from depression, and their conclusions are not uniform until now. This study aimed to investigate the correlation between the severity of depression in females and factors such as sex hormones and differences in sex hormone levels in females of different ages, exploring variations after treatment. Methods A total of 169 females with depression were selected and divided into the first-episode (91 cases) and recurrent (78 cases) groups. Then, on the basis of their age, the first-episode patients were divided into the young (48 cases, age 55 years); the patients with recurrent depression were classified into the young (37 cases, age 55 years). The patients were assessed in accordance with the International Classification of Diseases of mental and behavioral disorders. The serum progesterone, prolactin, estradiol, and testosterone levels in the patients were measured, and differences in sex hormone levels of the groups were analyzed. Results The estradiol level was negatively correlated with age and the prolactin level was positively correlated with occupation. The severity of depression in females was found to be negatively correlated with age. The serum progesterone and estradiol levels in the young group were significantly higher than those in the elderly group, regardless of the first episode or recurrence. Estradiol levels in the perimenopausal and elderly groups with first-episode depression were significantly higher than those in the same group with recurrent depression. However, there was no significant difference in the serum progesterone, prolactin, estradiol, and testosterone levels in the recurrent group before and after treatment. Conclusions Sex hormone levels, especially estradiol, varied among females of different ages suffering from depression. Recurrent depression also has a certain effect on sex hormone levels in females. Not only should the age and relapse be considered when studying the sex hormone levels of females with depression, but also attention should be paid to whether the patients have used antidepressants before their sexual hormonal testing.

The Andaman Sea (AS) is characterized by surprisingly weak stratification in its deep basin in drastic contrast to the nearby Bay of Bengal (BoB), presumably due to strong diapycnal mixing fertilized by the dissipation of internal tides. Here, we report on the first estimates of tidal mixing in the AS using idealized numerical simulations resolving the generation and evolution of low-mode internal tides. The estimation is based on a diagnostic analysis of the energetics of the simulated internal tides of both local and non-local origins. The results highlight the dominant role of the internal tides generated in the channels along the western boundary island chain in energizing diapycnal mixing in the entire AS. Tidal dissipation and mixing in the deep basin of the AS are found to be highly elevated, with the depth-integrated dissipation rate and the diapycnal diffusivity being O(10(-2)-10 ) W m(-2) and O(10(-3)-10(-2)) m(2) s(-1), respectively, both of which are 1-2 orders of magnitude larger than those in the deep BoB. These model-based estimates of tidal mixing are in general consistent with those from in situ conductivity-temperature-depth (CTD) measurements using the fine-scale parameterization. Our results suggest that the oft-used tidal mixing parameterization considering only local internal tide generation would underestimate the depth-integrated tidal dissipation in the AS by several orders of magnitude, highlighting therefore the necessity of considering contributions of non-local internal tides in parameterizing tidal dissipation and mixing in marginal seas like the AS.

Exposures to ambient air pollutants are well-known risk factors for childhood asthma and asthma exacerbation. It’s unknown whether different air pollutants individually or jointly affect pathophysiological mechanisms of asthma. In this study, we aim to integrate transcriptome and untargeted metabolome to identify dysregulated genetic and metabolic pathways that are associated with exposures to a mixture of ambient and traffic-related air pollutants among adults with asthma history. In this cross-sectional study, 102 young adults with childhood asthma history were enrolled from southern California in 2012. Whole blood transcriptome was measured using Illumina HumanHT-12 v4 Expression BeadChip, with 20,869 expression signatures. Serum untargeted metabolomics including 937 metabolites were analyzed using the Metabolon Ultra-high Performance Liquid Chromatography-Tandem Mass Spectrometry. Participants’ regional (NO2, O3, PM10, PM2.5) and near-roadway air pollution exposures averaged at one-month and one-year before study visit were estimated based on residential addresses. xMWAS network analysis and joint-pathway analysis were performed to identify subnetworks and genetic and metabolic pathways that were associated with air pollutants exposures adjusted for socio-characteristic covariates. Network analysis found that exposures to air pollutants mixture were connected to 357 gene markers and 92 metabolites. One-year and one-month averaged PM2.5 and NO2 exposures were associated with several amino acids related to serine, glycine, and beta-alanine metabolism. Lower serum levels of carnosine and aspartate, which were involved in beta-alanine metabolic pathway, as well as choline were also associated with worse asthma control (p

Ambient air pollutants are well-known risk factors for childhood asthma and asthma exacerbation. It is unknown whether different air pollutants individually or jointly affect pathophysiological mechanisms of asthma. In this study, we aim to integrate transcriptome and untargeted metabolome to identify dysregulated genetic and metabolic pathways that are associated with exposures to a mixture of ambient and traffic-related air pollutants among adults with asthma history. In this cross-sectional study, 102 young adults with childhood asthma history were enrolled from southern California in 2012. Whole blood transcriptome was measured with 20,869 expression signatures and serum untargeted metabolomics including 937 metabolites were analyzed by Metabolon, Inc. Participants’ exposures to regional air pollutants (NO(2), O(3), PM(10), PM(2.5)) and near-roadway air pollutants averaged at one month and one year before study visit were estimated based on residential addresses. xMWAS network analysis and joint-pathway analysis were performed to identify subnetworks and genetic and metabolic pathways that were associated with exposure to air pollutants adjusted for sociocharacteristic covariates. Network analysis found that exposures to air pollutants mixture were connected to 357 gene markers and 92 metabolites. One-year and one-month averaged PM(2.5) and NO(2) were associated with several amino acids related to serine, glycine, and beta-alanine metabolism. Lower serum levels of carnosine and aspartate, which were involved in beta-alanine metabolic pathway, as well as choline were also associated with worse asthma control (p

Metal-organic framework (MOF) is a promising template to synthesis highly efficient calcium-based sorbents for high temperature CO2 capture. However, the way of loading promoter on calcium oxide affects the CO2 sorption performance of MOF-derived sorbents. In this work, a series of MOF-derived sorbents with three promoter types (Al2O3, MgO, ZrO2) are synthesized from one-step synthesis method and two-step synthesis method to investigate the influence of loading strategy on the material structure and sorption behavior. Detailed characterization techniques and reaction kinetics are used to interpret the essential reason for different reactivity of the sorbents using two loading strategies. Loading strategy affects promoter loading, crystallite size, CO2 sorption capacity and sorption/desorption rate, but leads to a limited impact on reaction time. Two-step synthesis method contributes to a higher promoter loading for the sorbents, due to the absence of coordination competition between calcium and metal cations to form a bimetallic MOF template. Moreover, it is benefitted to yield higher CO2 sorption capacity and CO2 retention rate, even introduces a self-activation effect by reorganizing the material structure. The result provides a useful guide to optimize the connection way between promoter and calcium oxide for improving the sorption activity and thermal stability of CO2 sorbents.

BackgroundThe Household Air Pollution Intervention Network (HAPIN) trial aims to assess health benefits of a liquefied petroleum gas (LPG) cookfuel and stove intervention among women and children across four low- and middle-income countries (LMICs). We measured exposure contrasts for women, achievable under alternative conditions of biomass or LPG cookfuel use, at potential HAPIN field sites in India, to aid in site selection for the main trial.MethodsWe recruited participants from potential field sites within Villupuram and Nagapattinam districts in Tamil Nadu, India, that were identified during a feasibility assessment. We performed.(i) cross-sectional measurements on women (N = 79) using either biomass or LPG as their primary cookfuel and (ii) before-and-after measurements on pregnant women (N = 41), once at baseline while using biomass fuel and twice – at 1 and 2 months – after installation of an LPG stove and free fuel intervention. We involved participants to co-design clothing and instrument stands for personal and area sampling. We measured 24 or 48-h personal exposures and kitchen and ambient concentrations of fine particulate matter (PM2.5) using gravimetric samplers.ResultsIn the cross-sectional analysis, median (interquartile range, IQR) kitchen PM2.5 concentrations in biomass and LPG using homes were 134 μg/m3 [IQR:71–258] and 27 μg/m3 [IQR:20–47], while corresponding personal exposures were 75 μg/m3 [IQR:55–104] and 36 μg/m3 [IQR:26–46], respectively. In before-and-after analysis, median 48-h personal exposures for pregnant women were 72 μg/m3 [IQR:49–127] at baseline and 25 μg/m3 [IQR:18–35] after the LPG intervention, with a sustained reduction of 93% in mean kitchen PM2.5 concentrations and 78% in mean personal PM2.5 exposures over the 2 month intervention period. Median ambient concentrations were 23 μg/m3 [IQR:19–27). Participant feedback was critical in designing clothing and instrument stands that ensured high compliance.ConclusionsAn LPG stove and fuel intervention in the candidate HAPIN trial field sites in India was deemed suitable for achieving health-relevant exposure reductions. Ambient concentrations indicated limited contributions from other sources. Study results provide critical inputs for the HAPIN trial site selection in India, while also contributing new information on HAP exposures in relation to LPG interventions and among pregnant women in LMICs.Trial registrationClinicalTrials.Gov.NCT02944682; Prospectively registered on October 17, 2016.

Classical discriminative correlation filter (DCF) model suffers from boundary effects, several modified discriminative correlation filter models have been proposed to mitigate this drawback using enlarged search region, and remarkable performance improvement has been reported by related papers. However, model deterioration is still not well addressed when facing occlusion and other challenging scenarios. In this work, we propose a novel Temporally-regularized Context-aware Correlation Filters (TCCF) model to model the target appearance more robustly. We take advantage of the enlarged search region to obtain more negative samples to make the filter sufficiently trained, and a temporal regularizer, which restricting variation in filter models between frames, is seamlessly integrated into the original formulation. Our model is derived from the new discriminative learning loss formulation, a closed form solution for multidimensional features is provided, which is solved efficiently using Alternating Direction Method of Multipliers (ADMM). Extensive experiments on standard OTB-2015, TempleColor-128 and VOT-2016 benchmarks show that the proposed approach performs favorably against many state-of-the-art methods with real-time performance of 28fps on single CPU.

The Household Air Pollution Intervention Network trial is a multi-country study on the effects of a liquefied petroleum gas (LPG) stove and fuel distribution intervention on women's and children's health. There is limited data on exposure reductions achieved by switching from solid to clean cooking fuels in rural settings across multiple countries. As formative research in 2017, we recruited pregnant women and characterized the impact of the intervention on personal exposures and kitchen levels of fine particulate matter (PM2.5) in Guatemala, India, and Rwanda. Forty pregnant women were enrolled in each site. We measured cooking area concentrations of and personal exposures to PM2.5 for 24 or 48 h using gravimetric-based PM2.5 samplers at baseline and two follow-ups over two months after delivery of an LPG cookstove and free fuel supply. Mixed models were used to estimate PM2.5 reductions. Median kitchen PM2.5 concentrations were 296 μg/m3 at baseline (interquartile range, IQR: 158–507), 24 μg/m3 at first follow-up (IQR: 18–37), and 23 μg/m3 at second follow-up (IQR: 14–37). Median personal exposures to PM2.5 were 134 μg/m3 at baseline (IQR: 71–224), 35 μg/m3 at first follow-up (IQR: 23–51), and 32 μg/m3 at second follow-up (IQR: 23–47). Overall, the LPG intervention was associated with a 92% (95% confidence interval (CI): 90–94%) reduction in kitchen PM2.5 concentrations and a 74% (95% CI: 70–79%) reduction in personal PM2.5 exposures. Results were similar for each site. Conclusions The intervention was associated with substantial reductions in kitchen and personal PM2.5 overall and in all sites. Results suggest LPG interventions in these rural settings may lower exposures to the WHO annual interim target-1 of 35 μg/m3. The range of exposure contrasts falls on steep sections of estimated exposure-response curves for birthweight, blood pressure, and acute lower respiratory infections, implying potentially important health benefits when transitioning from solid fuels to LPG., Highlights • There was high uptake of an LPG stove and fuel intervention in 3 rural settings. • The LPG intervention was associated with a 92% reduction in kitchen PM2.5 levels. • The intervention was associated with a 74% reduction in personal exposure to PM2.5 • Maternal PM2.5 exposure was reduced to the WHO annual interim target-1 of 35 μg/m3. • Results from 3 countries indicate switching to clean fuel could improve health., Capsule summary: LPG stove and fuel intervention can reduce kitchen area and personal PM2.5 exposure levels in a pilot study of clean cookstove intervention trial. This strongly suggests switching to clean cook can improve health.

In view of the demand of 3D vision, we proposed a fully digital indirect time-of-flight SOC based on single-photon avalanche diode (SPAD). The single pixel unit of the SOC consists of an analog SPAD pixel module and a digital phase integration processing module and is designed by 180nm CIS CMOS technology. In this design, an all-digital design structured is used to collect phase information at high speed in an attempt to improve the frame rate of the sensor. We also propose a new quenching circuit that speeds up the detector quenching and controls the reset time to reduce the damage rate of SPAD.

Summary Pneumonia is a leading killer of children younger than 5 years despite high vaccination coverage, improved nutrition, and widespread implementation of the Integrated Management of Childhood Illnesses algorithm. Assessing the effect of interventions on childhood pneumonia is challenging because the choice of case definition and surveillance approach can affect the identification of pneumonia substantially. In anticipation of an intervention trial aimed to reduce childhood pneumonia by lowering household air pollution, we created a working group to provide recommendations regarding study design and implementation. We suggest to, first, select a standard case definition that combines acute (≤14 days) respiratory symptoms and signs and general danger signs with ancillary tests (such as chest imaging and pulse oximetry) to improve pneumonia identification; second, to prioritise active hospital-based pneumonia surveillance over passive case finding or home-based surveillance to reduce the risk of non-differential misclassification of pneumonia and, as a result, a reduced effect size in a randomised trial; and, lastly, to consider longitudinal follow-up of children younger than 1 year, as this age group has the highest incidence of severe pneumonia.

Background: High quality personal exposure data is fundamental to understanding the health implications of household energy interventions, interpreting analyses across assigned study arms, and characterizing exposure–response relationships for household air pollution. This paper describes the exposure data collection for the Household Air Pollution Intervention Network (HAPIN), a multicountry randomized controlled trial of liquefied petroleum gas stoves and fuel among 3,200 households in India, Rwanda, Guatemala, and Peru. Objectives: The primary objectives of the exposure assessment are to estimate the exposure contrast achieved following a clean fuel intervention and to provide data for analyses of exposure–response relationships across a range of personal exposures. Methods: Exposure measurements are being conducted over the 3-y time frame of the field study. We are measuring fine particulate matter [PM

Additional file 1.