35 research outputs found
Phytoplankton blooms weakly influence the cloud forming ability of sea spray aerosol
After many field studies, the establishment of connections between marine microbiological processes, sea spray aerosol (SSA) composition, and cloud condensation nuclei (CCN) has remained an elusive challenge. In this study, we induced algae blooms to probe how complex changes in seawater composition impact the ability of nascent SSA to act as CCN, quantified by using the apparent hygroscopicity parameter (Îșapp). Throughout all blooms, Îșapp ranged between 0.7 and 1.4 (average 0.95â±â0.15), consistent with laboratory investigations using algaeâproduced organic matter, but differing from climate model parameterizations and in situ SSA generation studies. The size distribution of nascent SSA dictates that changes in Îșapp associated with biological processing induce less than 3% change in expected CCN concentrations for typical marine cloud supersaturations. The insignificant effect of hygroscopicity on CCN concentrations suggests that the SSA production flux and/or secondary aerosol chemistry may be more important factors linking ocean biogeochemistry and marine clouds.Key PointsChanges in seawater and sea spray composition did not strongly affect expected CCN concentrationsBlooms may impact clouds more strongly through changes in aerosol flux or secondary chemistryModel parameterizations likely overestimate changes in cloud nuclei due to primary marine organicsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134444/1/grl54978_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134444/2/grl54978-sup-0001-supinfo.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134444/3/grl54978.pd
Genome-wide structural variant analysis identifies risk loci for non-Alzheimerâs dementias
We characterized the role of structural variants, a largely unexplored type of genetic variation, in two non-Alzheimerâs dementias, namely Lewy body dementia (LBD) and frontotemporal dementia (FTD)/amyotrophic lateral sclerosis (ALS). To do this, we applied an advanced structural variant calling pipeline (GATK-SV) to short-read whole-genome sequence data from 5,213 European-ancestry cases and 4,132 controls. We discovered, replicated, and validated a deletion in TPCN1 as a novel risk locus for LBD and detected the known structural variants at the C9orf72 and MAPT loci as associated with FTD/ALS. We also identified rare pathogenic structural variants in both LBD and FTD/ALS. Finally, we assembled a catalog of structural variants that can be mined for new insights into the pathogenesis of these understudied forms of dementia
Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study
Summary
Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally.
Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies
have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of
the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income
countries globally, and identified factors associated with mortality.
Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to
hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis,
exomphalos, anorectal malformation, and Hirschsprungâs disease. Recruitment was of consecutive patients for a
minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical
status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary
intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause,
in-hospital mortality for all conditions combined and each condition individually, stratified by country income status.
We did a complete case analysis.
Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital
diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal
malformation, and 517 with Hirschsprungâs disease) from 264 hospitals (89 in high-income countries, 166 in middleincome
countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male.
Median gestational age at birth was 38 weeks (IQR 36â39) and median bodyweight at presentation was 2·8 kg (2·3â3·3).
Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income
countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups).
Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome
countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries;
pâ€0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients
combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88â4·11],
p<0·0001; middle-income vs high-income countries, 2·11 [1·59â2·79], p<0·0001), sepsis at presentation (1·20
[1·04â1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention
(ASA 4â5 vs ASA 1â2, 1·82 [1·40â2·35], p<0·0001; ASA 3 vs ASA 1â2, 1·58, [1·30â1·92], p<0·0001]), surgical safety
checklist not used (1·39 [1·02â1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed
(ventilation 1·96, [1·41â2·71], p=0·0001; parenteral nutrition 1·35, [1·05â1·74], p=0·018). Administration of
parenteral nutrition (0·61, [0·47â0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65
[0·50â0·86], p=0·0024) or percutaneous central line (0·69 [0·48â1·00], p=0·049) were associated with lower mortality.
Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome,
middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will
be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger
than 5 years by 2030
COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study
Background:
The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms.
Methods:
International, prospective observational study of 60â109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms.
Results:
âTypicalâ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (â€â18 years: 69, 48, 23; 85%), older adults (â„â70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each Pâ<â0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country.
Interpretation:
This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men
New tools and paradigms for the analysis of sea spray aerosols by single particle mass spectrometry
Aerosols can influence the chemistry of the atmosphere as well as also impact global climate by directly scattering light and modifying cloud properties. Sea spray aerosols (SSA) are the second most abundant natural aerosol globally and have the potential to strongly influence atmospheric chemistry and scattering of solar radiation in marine regions. In this dissertation, an ATOFMS was utilized to characterize the chemistry of SSA, focusing on describing the mixing state of the population and also distributions of chemical components within particles. Existing paradigms describing SSA via single particle mass spectrometers (SPMS) were expanded upon and SPMS descriptions of SSA with results from offline spectromicroscopy and quantitative ensemble techniques were unifed. This research was facilitated by the development of a new SPMS data analysis toolkit, which enabled both script-based and visual data exploration all within a single programming environment. Utilizing this toolkit, ATOFMS depth profiling studies of supermicron SSA illustrated that much of the variation in SSA mass spectral signatures is likely due to inconsistent desorption of particles with core-shell morphologies, helping to unify online and offline descriptions of the SSA mixing state. In a study of SSA generated from a model seawater solution, the interpretation of single particle ion signatures were informed by complimentary offline microscopy images and quantitative chemical composition measurements. It was deduced that the high calcium signal and total negative ion yield were likely a product of the coordination of calcium to carboxylate in the desorbed and ionized particle. For the first time, depth profiling and size dependence analyses were coupled to isolate likely microbial ion signatures (BioSS) from within the SSA population. These new paradigms were applied to interpret SSA ATOFMS data sets from collaborative studies, where the influence of biologically mediated changes in seawater chemistry on SSA chemistry and climate impacts were explored. Concentrations of BioSS and warm ice nucleating particles were correlated, suggesting microbe-containing SSA may effectively nucleate ice in marine clouds. Finally, ATOFMS and aerosol mass spectrometry descriptions of SSA helped establish a mechanistic framework illustrating how SSA chemical composition is modulated not only by phytoplankton primary production but also by microbial degradation processes
Effect of Structural Heterogeneity in Chemical Composition on Online Single-Particle Mass Spectrometry Analysis of Sea Spray Aerosol Particles
Knowledge of the surface composition
of sea spray aerosols (SSA)
is critical for understanding and predicting climate-relevant impacts.
Offline microscopy and spectroscopy studies have shown that dry supermicron
SSA tend to be spatially heterogeneous particles with sodium- and
chloride-rich cores surrounded by organic enriched surface layers
containing minor inorganic seawater components such as magnesium and
calcium. At the same time, single-particle mass spectrometry reveals
several different mass spectral ion patterns, suggesting that there
may be a number of chemically distinct particle types. This study
investigates factors controlling single particle mass spectra of nascent
supermicron SSA. Depth profiling experiments conducted on SSA generated
by a fritted bubbler and total ion intensity analysis of SSA generated
by a marine aerosol reference tank were compared with observations
of ambient SSA observed at two coastal locations. Analysis of SSA
produced by utilizing controlled laboratory methods reveals that single-particle
mass spectra with weak sodium ion signals can be produced by the desorption
of the surface of typical dry SSA particles composed of salt cores
and organic-rich coatings. Thus, this lab-based study for the first
time unifies findings from offline and online measurements as well
as lab and field studies of the SSA particle-mixing state
Expanding Single Particle Mass Spectrometer Analyses for the Identification of Microbe Signatures in Sea Spray Aerosol
Ocean-derived microbes
in sea spray aersosol (SSA) have the potential
to influence climate and weather by acting as ice nucleating particles
in clouds. Single particle mass spectrometers (SPMSs), which generate <i>in situ</i> single particle composition data, are excellent
tools for characterizing aerosols under changing environmental conditions
as they can provide high temporal resolution and require no sample
preparation. While SPMSs have proven capable of detecting microbes,
these instruments have never been utilized to definitively identify
aerosolized microbes in ambient sea spray aersosol. In this study,
an aerosol time-of-flight mass spectrometer was used to analyze laboratory
generated SSA produced from natural seawater in a marine aerosol reference
tank. We present the first description of a population of biological
SSA mass spectra (BioSS), which closely match the ion signatures observed
in previous terrestrial microbe studies. The fraction of BioSS dramatically
increased in the largest supermicron particles, consistent with field
and laboratory measurements of microbes ejected by bubble bursting,
further supporting the assignment of BioSS mass spectra as microbes.
Finally, as supported by analysis of inorganic ion signals, we propose
that dry BioSS particles have heterogeneous structures, with microbes
adhered to sodium chloride nodules surrounded by magnesium-enriched
coatings. Consistent with this structure, chlorine-containing ion
markers were ubiquitous in BioSS spectra and identified as possible
tracers for distinguishing recently aerosolized marine from terrestrial
microbes
Recommended from our members
Secondary Marine Aerosol Plays a Dominant Role over Primary Sea Spray Aerosol in Cloud Formation.
Marine aerosols play a critical role in impacting our climate by seeding clouds over the oceans. Despite decades of research, key questions remain regarding how ocean biological activity changes the composition and cloud-forming ability of marine aerosols. This uncertainty largely stems from an inability to independently determine the cloud-forming potential of primary versus secondary marine aerosols in complex marine environments. Here, we present results from a unique 6-day mesocosm experiment where we isolated and studied the cloud-forming potential of primary and secondary marine aerosols over the course of a phytoplankton bloom. The results from this controlled laboratory approach can finally explain the long-observed changes in the hygroscopic properties of marine aerosols observed in previous field studies. We find that secondary marine aerosols, consisting of sulfate, ammonium, and organic species, correlate with phytoplankton biomass (i.e., chlorophyll-a concentrations), whereas primary sea spray aerosol does not. Importantly, the measured CCN activity (Îșapp = 0.59 ± 0.04) of the resulting secondary marine aerosol matches the values observed in previous field studies, suggesting secondary marine aerosols play the dominant role in affecting marine cloud properties. Given these findings, future studies must address the physical, chemical, and biological factors controlling the emissions of volatile organic compounds that form secondary marine aerosol, with the goal of improving model predictions of ocean biology on atmospheric chemistry, clouds, and climate
Recommended from our members
Secondary Marine Aerosol Plays a Dominant Role over Primary Sea Spray Aerosol in Cloud Formation.
Marine aerosols play a critical role in impacting our climate by seeding clouds over the oceans. Despite decades of research, key questions remain regarding how ocean biological activity changes the composition and cloud-forming ability of marine aerosols. This uncertainty largely stems from an inability to independently determine the cloud-forming potential of primary versus secondary marine aerosols in complex marine environments. Here, we present results from a unique 6-day mesocosm experiment where we isolated and studied the cloud-forming potential of primary and secondary marine aerosols over the course of a phytoplankton bloom. The results from this controlled laboratory approach can finally explain the long-observed changes in the hygroscopic properties of marine aerosols observed in previous field studies. We find that secondary marine aerosols, consisting of sulfate, ammonium, and organic species, correlate with phytoplankton biomass (i.e., chlorophyll-a concentrations), whereas primary sea spray aerosol does not. Importantly, the measured CCN activity (Îșapp = 0.59 ± 0.04) of the resulting secondary marine aerosol matches the values observed in previous field studies, suggesting secondary marine aerosols play the dominant role in affecting marine cloud properties. Given these findings, future studies must address the physical, chemical, and biological factors controlling the emissions of volatile organic compounds that form secondary marine aerosol, with the goal of improving model predictions of ocean biology on atmospheric chemistry, clouds, and climate