Various mitigation measures have been implemented to fight the coronavirus disease 2019 (COVID-19) pandemic, including widely adopted social distancing and mandated face covering. However, assessing ...the effectiveness of those intervention practices hinges on the understanding of virus transmission, which remains uncertain. Here we show that airborne transmission is highly virulent and represents the dominant route to spread the disease. By analyzing the trend and mitigation measures in Wuhan, China, Italy, and New York City, from January 23 to May 9, 2020, we illustrate that the impacts of mitigation measures are discernable from the trends of the pandemic. Our analysis reveals that the difference with and without mandated face covering represents the determinant in shaping the pandemic trends in the three epicenters. This protective measure alone significantly reduced the number of infections, that is, by over 78,000 in Italy from April 6 to May 9 and over 66,000 in New York City from April 17 to May 9. Other mitigation measures, such as social distancing implemented in the United States, are insufficient by themselves in protecting the public. We conclude that wearing of face masks in public corresponds to the most effective means to prevent interhuman transmission, and this inexpensive practice, in conjunction with simultaneous social distancing, quarantine, and contact tracing, represents the most likely fighting opportunity to stop the COVID-19 pandemic. Our work also highlights the fact that sound science is essential in decision-making for the current and future public health pandemics.
Although regional haze adversely affects human health and possibly counteracts global warming from increasing levels of greenhouse gases, the formation and radiative forcing of regional haze on ...climate remain uncertain. By combining field measurements, laboratory experiments, and model simulations, we show a remarkable role of black carbon (BC) particles in driving the formation and trend of regional haze. Our analysis of long-term measurements in China indicates declined frequency of heavy haze events along with significantly reduced SO₂, but negligibly alleviated haze severity. Also, no improving trend exists for moderate haze events. Our complementary laboratory experiments demonstrate that SO₂ oxidation is efficiently catalyzed on BC particles in the presence of NO₂ and NH₃, even at low SO₂ and intermediate relative humidity levels. Inclusion of the BC reaction accounts for about 90–100% and 30–50%of the sulfate production during moderate and heavy haze events, respectively. Calculations using a radiative transfer model and accounting for the sulfate formation on BC yield an invariant radiative forcing of nearly zero W m−2 on the top of the atmosphere throughout haze development, indicating small net climatic cooling/warming but large surface cooling, atmospheric heating, and air stagnation. This BC catalytic chemistry facilitates haze development and explains the observed trends of regional haze in China. Our results imply that reduction of SO₂ alone is insufficient in mitigating haze occurrence and highlight the necessity of accurate representation of the BC chemical and radiative properties in predicting the formation and assessing the impacts of regional haze.
High levels of ultrafine particles (UFPs; diameter of less than 50 nm) are frequently produced from new particle formation under urban conditions, with profound implications on human health, weather, ...and climate. However, the fundamental mechanisms of new particle formation remain elusive, and few experimental studies have realistically replicated the relevant atmospheric conditions. Previous experimental studies simulated oxidation of one compound or a mixture of a few compounds, and extrapolation of the laboratory results to chemically complex air was uncertain. Here, we show striking formation of UFPs in urban air from combining ambient and chamber measurements. By capturing the ambient conditions (i.e., temperature, relative humidity, sunlight, and the types and abundances of chemical species), we elucidate the roles of existing particles, photochemistry, and synergy of multipollutants in new particle formation. Aerosol nucleation in urban air is limited by existing particles but negligibly by nitrogen oxides. Photooxidation of vehicular exhaust yields abundant precursors, and organics, rather than sulfuric acid or base species, dominate formation of UFPs under urban conditions. Recognition of this source of UFPs is essential to assessing their impacts and developing mitigation policies. Our results imply that reduction of primary particles or removal of existing particles without simultaneously limiting organics from automobile emissions is ineffective and can even exacerbate this problem.
Photochemical oxidation of aromatic hydrocarbons leads to tropospheric ozone and secondary organic aerosol (SOA) formation, with profound implications for air quality, human health, and climate. ...Toluene is the most abundant aromatic compound under urban environments, but its detailed chemical oxidation mechanism remains uncertain. From combined laboratory experiments and quantum chemical calculations, we show a toluene oxidation mechanism that is different from the one adopted in current atmospheric models. Our experimental work indicates a larger-than-expected branching ratio for cresols, but a negligible formation of ring-opening products (e.g., methylglyoxal). Quantum chemical calculations also demonstrate that cresols are much more stable than their corresponding peroxy radicals, and, for the most favorable OH (ortho) addition, the pathway of H extraction by O₂ to form the cresol proceeds with a smaller barrier than O₂ addition to form the peroxy radical. Our results reveal that phenolic (rather than peroxy radical) formation represents the dominant pathway for toluene oxidation, highlighting the necessity to reassess its role in ozone and SOA formation in the atmosphere.
Cognitive-behavioral treatments for panic disorder (PD) emphasize interoceptive exposure (IE) to target anxiety sensitivity (AS) but vary considerably in its manner of delivery. This randomized ...controlled trial was conducted to compare the efficacy of the low-dose delivery of IE exercises often prescribed in treatment protocols to an intensive form of IE hypothesized to optimize inhibitory learning. Participants (N = 120) with elevated AS were randomly assigned to one of four single-session interventions: (a) low-dose IE as prescribed in Barlow and Craske's Panic Control Treatment, (b) low-dose IE without controlled breathing or a lengthy between-trial rest period, (c) intensive IE, or (d) expressive writing control. Compared to the other conditions, intensive IE produced significantly greater reductions in AS and fearful responding to a straw breathing task from pretreatment to posttreatment. Maintenance of gains during the follow-up period did not differ between conditions. Changes in fear toleration and negative outcome expectancies fully mediated the superior efficacy of intensive IE over low-dose IE. The two low intensity IE conditions produced particularly high rates of fear sensitization on between-trial and outcome variables. The findings suggest that the intensive delivery of IE exercises has the potential to improve the efficacy of exposure-based treatments for PD.
•Interoceptive exposure (IE) for panic is often delivered in a low-dose manner.•This randomized controlled trial compared low-dose IE to high-intensity IE.•Intensive IE was significantly more effective than low-dose IE.•Intensive IE optimized improvement in catastrophic predictions and fear toleration.•Low-dose IE produced higher rates of fear sensitization than intensive IE.
This study explores the effects of two humor styles—pure humor and satire—on audiences’ Twitter engagement intentions as well as their attitudes toward mRNA Covid-19 vaccines. In an online ...between-subjects experiment (N = 484), these styles were embedded within a scientist’s tweet about the vaccines. The results showed that, compared to a no humor tweet, both pure humor and satire increased audience’s expectancy violation, subsequently decreasing both outcomes. Superiority as an individual trait also moderated the relationship between humor styles and both expectancy violation and Twitter engagement. These findings broaden our understanding of different humor styles in science communication on Twitter.
We study the relative importance of social factors (including household, workplace, and neighborhood peer effects) and personal characteristics (including age, gender, tax rates, and funds under ...management) for asset allocation decisions. The most important factors (in order) are household peer effects, personal characteristics and workplace peer effects. Neighborhood peer effects and financial advice play a less important role. We use instrumental variables for both household and workplace peer effects and find results that are consistent with causal peer effects.
Secondary organic aerosol (SOA) represents a major constituent of tropospheric fine particulate matter, with profound implications for human health and climate. However, the chemical mechanisms ...leading to SOA formation remain uncertain, and atmospheric models consistently underpredict the global SOA budget. Small α-dicarbonyls, such as methylglyoxal, are ubiquitous in the atmosphere because of their significant production from photooxidation of aromatic hydrocarbons from traffic and industrial sources as well as from biogenic isoprene. Current experimental and theoretical results on the roles of methylglyoxal in SOA formation are conflicting. Using quantum chemical calculations, we show cationic oligomerization of methylglyoxal in aqueous media. Initial protonation and hydration of methylglyoxal lead to formation of diols/tetrol, and subsequent protonation and dehydration of diols/tetrol yield carbenium ions, which represent the key intermediates for formation and propagation of oligomerization. On the other hand, our results reveal that the previously proposed oligomerization via hydration for methylglyoxal is kinetically and thermodynamically implausible. The carbenium ion-mediated mechanism occurs barrierlessly on weakly acidic aerosols and cloud/fog droplets and likely provides a key pathway for SOA formation from biogenic and anthropogenic emissions.
As social media become increasingly important for science communication, scientists are grappling with their new role on these platforms. While some have called for the increased presence and ...training of scientists on social media, others prefer to leverage the influence of social media influencers for science communication. This study explores the effects of source identity (scientist or influencer) and self-disclosure type (personal or professional) on perceptions of authenticity and expertise, as well as parasocial interactions. In an online between-subjects experiment (N = 1579), participants rated scientists on Twitter as more authentic and qualified than influencers, and rated Twitter profiles with professional self-disclosure as more qualified than profiles with personal self-disclosure. Subsequently, participants indicated stronger parasocial interactions, higher information-seeking intentions, and higher prosocial intentions. Anti-intellectualism was found to moderate these relationships. These findings suggest that scientists can employ certain strategies as they seek to establish themselves and reach wider audiences on social media platforms.
Two potential platform technologies for the oral delivery of protein therapeutics were synthesized and tested. pH-responsive poly(itaconic acid-co-N-vinyl-2-pyrrolidone) (P(IA-co-NVP)) hydrogel ...microparticles were tested in vitro with model proteins salmon calcitonin, urokinase, and rituximab to determine the effects of particle size, protein size, and crosslinking density on oral delivery capability. Particle size showed no significant effect on overall delivery potential but did improve percent release of encapsulated protein over the micro-scale particle size range studied. Protein size was shown to have a significant impact on the delivery capability of the P(IA-co-NVP) hydrogel. We show that when using P(IA-co-NVP) hydrogel microparticles with 3mol% tetra(ethylene glycol) dimethacrylate crosslinker, a small polypeptide (salmon calcitonin) loads and releases up to 45μg/mg hydrogel while the mid-sized protein urokinase and large monoclonal antibody rituximab load and release only 19 and 24μg/mg hydrogel, respectively. We further demonstrate that crosslinking density offers a simple method for tuning hydrogel properties to variously sized proteins. Using 5mol% TEGDMA crosslinker offers optimal performance for the small peptide, salmon calcitonin, whereas lower crosslinking density of 1mol% offers optimal performance for the much larger protein rituximab. Finally, an enzymatically-degradable hydrogels of P(MAA-co-NVP) crosslinked with the peptide sequence MMRRRKK were synthesized and tested in simulated gastric and intestinal conditions. These hydrogels offer ideal loading and release behavior, showing no degradative release of encapsulated salmon calcitonin in gastric conditions while yielding rapid and complete release of encapsulated protein within 1h in intestinal conditions.
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