35 research outputs found
Regulations to Respond to the Potential Benefits and Perils of SelfDriving Cars Analysis and Recommendations for Advancing Equity and Environmental Sustainability
The mobility system in the United States is unsafe, inequitable, and environmentally destructive. Most Americans rely on personally owned, individually occupied, and gas-powered cars—a status quo that leads to tens of thousands of people dying each year in collisions, creates barriers to employment and other opportunities for people of color and people with low incomes, and maintains a resource intensive transportation system that contributes to climate change and spurs sprawling land uses that destroy ecologies. Autonomous vehicles (AVs)—self-driving cars that can travel along publicly accessible streets some or all of the time without human involvement—could help mitigate these problems, if they are implemented in a thoughtful, well-regulated manner. However, if deployed haphazardly with inadequate oversight and regulation, they could produce even worse inequities than those caused by the current system.To evaluate the current landscape for AV deployment and use in the United States, we conducted a study focusing on automobile-sized AVs designed for passenger use as opposed to other types of AVs that could be used for public transit service or freight. Through a scholarship review, a scan of legislation nationwide, and interviews with stakeholders, we examine key potential benefits that AVs could generate, as well as the problems they could exacerbate. Carefully designed regulations could help ensure that these new technologies improve access to mobility and reduce pollution
ASCOT: a text mining-based web-service for efficient search and assisted creation of clinical trials
Clinical trials are mandatory protocols describing medical research on humans and among the most valuable sources of medical practice evidence. Searching for trials relevant to some query is laborious due to the immense number of existing protocols. Apart from search, writing new trials includes composing detailed eligibility criteria, which might be time-consuming, especially for new researchers. In this paper we present ASCOT, an efficient search application customised for clinical trials. ASCOT uses text mining and data mining methods to enrich clinical trials with metadata, that in turn serve as effective tools to narrow down search. In addition, ASCOT integrates a component for recommending eligibility criteria based on a set of selected protocols
A blood RNA transcriptome signature for COVID-19.
BACKGROUND: COVID-19 is a respiratory viral infection with unique features including a more chronic course and systemic disease manifestations including multiple organ involvement; and there are differences in disease severity between ethnic groups. The immunological basis for disease has not been fully characterised. Analysis of whole-blood RNA expression may provide valuable information on disease pathogenesis. METHODS: We studied 45 patients with confirmed COVID-19 infection within 10 days from onset of illness and a control group of 19 asymptomatic healthy volunteers with no known exposure to COVID-19 in the previous 14 days. Relevant demographic and clinical information was collected and a blood sample was drawn from all participants for whole-blood RNA sequencing. We evaluated differentially-expressed genes in COVID-19 patients (log2 fold change ≥ 1 versus healthy controls; false-discovery rate 0.05). CONCLUSIONS: The whole-blood transcriptome of COVID-19 has overall similarity with other respiratory infections but there are some unique pathways that merit further exploration to determine clinical relevance. The approach to a disease score may be of value, but needs further validation in a population with a greater range of disease severity
Finishing the euchromatic sequence of the human genome
The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead
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Thermal optimality of net ecosystem exchange of carbon dioxide and underlying mechanisms
It is well established that individual organisms can acclimate and adapt to temperature to optimize their functioning. However, thermal optimization of ecosystems, as an assemblage of organisms, has not been examined at broad spatial and temporal scales. Here, we compiled data from 169 globally distributed sites of eddy covariance and quantified the temperature response functions of net ecosystem exchange (NEE), an ecosystem-level property, to determine whether NEE shows thermal optimality and to explore the underlying mechanisms. We found that the temperature response of NEE followed a peak curve, with the optimum temperature (corresponding to the maximum magnitude of NEE) being positively correlated with annual mean temperature over years and across sites. Shifts of the optimum temperature of NEE were mostly a result of temperature acclimation of gross primary productivity (upward shift of optimum temperature) rather than changes in the temperature sensitivity of ecosystem respiration. Ecosystem-level thermal optimality is a newly revealed ecosystem property, presumably reflecting associated evolutionary adaptation of organisms within ecosystems, and has the potential to significantly regulate ecosystemclimate change feedbacks. The thermal optimality of NEE has implications for understanding fundamental properties of ecosystems in changing environments and benchmarking global models.This is the publisher’s final pdf. The published article is copyrighted by New Phytologist Trust and can be found at: http://www.newphytologist.org/Keywords: Climate change, Temperature acclimation, Optimum temperature, Thermal optimality, Temperature adaptatio
Weakly Coordinating Organic Cations are Intrinsically Capable of Supporting CO2 Reduction Catalysis
The rates and selectivity of electrochemical CO2 reduction are known to be strongly influenced by the identity of alkali cations in the medium. However, experimentally, it remains unclear whether cation effects arise predominantly from coordinative stabilization of surface intermediates or from changes in the mean-field electrostatic environment at the interface. Herein, we show that Au- and Ag-catalyzed CO2 reduction can occur in the presence of weakly coordinating (poly)tetraalkylammonium cations. Through competition experiments in which the catalytic activity of Au was monitored as a function of the ratio of the organic to metal cation, we identify regimes in which the organic cation exclusively controls CO2 reduction selectivity and activity. We observe substantial CO production in this regime, suggesting that CO2 reduction catalysis can occur in the absence of Lewis acidic cations and thus, coordinative interactions between the electrolyte cations and surface-bound intermediates are not required for CO2 activation. For both Au and Ag, we find that tetraalkylammonium cations support catalytic activity for CO2 reduction on par with alkali metal cations, but with distinct cation activity trends between Au and Ag. These findings support a revision in electrolyte design rules to include water-soluble organic cation salts as potential supporting electrolytes for CO2 electrolysis
An NADH-Inspired Redox Mediator Strategy to Promote Second-Sphere Electron and Proton Transfer for Cooperative Electrochemical CO2 Reduction Catalyzed by Iron Porphyrin
We present a bioinspired strategy for enhancing electrochemical carbon dioxide reduction catalysis by cooperative use of base-metal molecular catalysts with intermolecular second-sphere redox mediators that facilitate both electron and proton transfer. Functional synthetic mimics of the biological redox cofactor NADH, which are electrochemically stable and are capable of mediating both electron and proton transfer, can enhance the activity of an iron porphyrin catalyst for electrochemical reduction of CO2 to CO, achieving a 13-fold rate improvement without altering the intrinsic high selectivity of this catalyst platform for CO2 versus proton reduction. Evaluation of a systematic series of NADH analogs and redox-inactive control additives with varying proton and electron reservoir properties reveals that both electron and proton transfer contribute to the observed catalytic enhancements. This work establishes that second-sphere dual control of electron and proton inventories is a viable design strategy for developing more effective electrocatalysts for CO2 reduction, providing a starting point for broader applications of this approach to other multi-electron, multi-proton transformations
Adsorbed Cobalt Porphyrins Act like Metal Surfaces in Electrocatalysis
Carbon electrodes chemically modified with molecular active sites are potent catalysts for key energy conver-sion reactions. Generally, it is assumed that these molecularly modified electrodes operate by the same redox mediation mechanisms observed for soluble molecules, in which electron transfer and substrate activation occur in separate elementary steps. Here, we uncover that, depending on the solvent, carbon-bound cobalt porphyrin can carry out electrolysis by the non-mediated mechanisms of metal surfaces in which electron transfer and substrate activation are concerted. We chemically modify glassy carbon electrodes with cobalt tetraphenylpor-phyrin units that are anchored by flexible aliphatic linkages to form CH-CoTPP. In acetonitrile, CH-CoTPP dis-plays a clear outer-sphere Co(II/I) process which catalyzes the H2 evolution reaction by a step-wise, redox-mediated reaction sequence. In contrast, clear surface redox waves are not observed for CH-CoTPP in aqueous media and H2 evolution proceeds via a non-mediated, concerted proton-electron transfer reaction sequence over a wide pH range. The data suggest that, in aqueous electrolyte, the CoTPP fragments reside inside the electro-chemical double layer and are electrostatically coupled to the surface. This coupling allows CH-CoTPP to carry out catalysis without being pinned to the redox potential of the molecular fragment. These studies highlight that the simple adsorption of molecules can lead to reaction mechanisms typically reserved for metal surfaces, ex-posing new principles for the design of molecularly-modified electrodes
Open Circuit Potential Decay Transients Quantify Non-Equilibrium Local pH During Electrocatalysis
Many key energy conversion reactions are proton-coupled electron transfer (PCET) reactions that consume or generate protons at electrode surfaces. Thus, catalytic turnover can generate non-equilibrium local pH environments at the surface that differ substantially from that of the bulk. Quantitative insight into the magnitude of this interfacial pH swing is a prerequisite for understanding and designing efficient systems for energy conversion, but is difficult to measure, particularly under high current density operation; with complex gas diffusion electrodes (GDEs); and with membrane-decorated surfaces employed in functional devices. Herein, we develop and validate a general methodology for experimentally quantifying interfacial pH swings using open circuit potential (OCP) decay transients. Using this method, we quantify the impact of buffer strength, supporting electrolyte composition, and the presence of cation exchange polymer overlayers on the polarization-induced pH swing on Pt GDEs. We find that modest current densities of −30 mA cm−2 are sufficient to sustain pH swings of > 2 pH units, even for strongly buffered solutions. Meanwhile, the addition of alkali supporting electrolyte to unbuffered, acidic electrolyte can induce pH swings so large that the polarized electrode environment becomes strongly alkaline. The presence of a Nafion polymer overlayer containing fixed anionic charges serves to further augment the interfacial pH swing, resulting in a similar pH swing at half the applied current density. The transport characteristics of these systems were analytically modelled, enabling direct calculation of boundary layer thickness and quantitative prediction of the OCP decay transient. These studies establish methods for quantifying local pH swings and highlight the dramatic variation in local pH relative to the bulk under many electrolyte conditions