To study the U.S. public's health behaviors, attitudes, and policy opinions about COVID-19 in the earliest weeks of the national health crisis (March 20-23, 2020).
We designed and fielded an original ...representative survey of 3,000 American adults between March 20-23, 2020 to collect data on a battery of 38 health-related behaviors, government policy preferences on COVID-19 response and worries about the pandemic. We test for partisan differences COVID-19 related policy attitudes and behaviors, measured in three different ways: party affiliation, intended 2020 Presidential vote, and self-placed ideological positioning. Our multivariate approach adjusts for a wide range of individual demographic and geographic characteristics that might confound the relationship between partisanship and health behaviors, attitudes, and preferences.
We find that partisanship-measured as party identification, support for President Trump, or left-right ideological positioning-explains differences in Americans across a wide range of health behaviors and policy preferences. We find no consistent evidence that controlling for individual news consumption, the local policy environment, and local pandemic-related deaths erases the observed partisan differences in health behaviors, beliefs, and attitudes. In further analyses, we use a LASSO regression approach to select predictors, and find that a partisanship indicator is the most commonly selected predictor across the 38 dependent variables that we study.
Our analysis of individual self-reported behavior, attitudes, and policy preferences in response to COVID-19 reveals that partisanship played a central role in shaping individual responses in the earliest months of the COVID-19 pandemic. These results indicate that partisan differences in responding to a national public health emergency were entrenched from the earliest days of the pandemic.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The FeFe hydrogenases (H2ases) catalyze the redox reaction that interconverts protons and H2. This area of biocatalysis has attracted attention because the metal-based chemistry is unusual, and the ...reactions have practical implications. The active site consists of a 4Fe–4S cluster bridged to a Fe2(μ-dithiolate)(CN)2(CO)3 z center (z = 1– and 2−). The dithiolate cofactor is HN(CH2S)22–, called the azadithiolate (adtH2–). Although many derivatives of Fe2(SR)2(CO)6–x L x are electrocatalysts for the hydrogen evolution reaction (HER), most operate by slow nonbiomimetic pathways. Biomimetic hydrogenogenesis is thought to involve intermediates, wherein the hydride substrate is adjacent to the amine of the adtH, being bonded to only one Fe center. Formation of terminal hydride complexes is favored when the diiron carbonyl models contain azadithiolate. Although unstable in the free state, the adt cofactor is stable once it is affixed to the Fe2 center. It can be prepared by alkylation of Fe2(SH)2(CO)6 with formaldehyde in the presence of ammonia (to give adtH derivatives) or amines (to give adtR derivatives). Weak acids protonate Fe2(adtR)(CO)2(PR3)4 to give terminal hydrido (term-H) complexes. In contrast, protonation of the related 1,3-propanedithiolate (pdt2−) complexes Fe2(pdt)(CO)2(PR3)4 requires strong acids. The amine in the azadithiolate is a kinetically fast base, relaying protons to and from the iron, which is a kinetically slow base. The crystal structure of the doubly protonated model (term-H)Fe2(HadtH)(CO)2(dppv)22+ confirms the presence of both ammonium and terminal hydrido centers, which interact through a dihydrogen bond (dppv = cis-C2H2(PPh2)2). DFT calculations indicate that this H---H interaction is sensitive to the counterions and is strengthened upon reduction of the diiron center. For the monoprotonated models, the hydride (term-H)Fe2(adtH)(CO)2(dppv)2+ exists in equilibrium with the ammonium tautomer Fe2(HadtH)(CO)2(dppv)2+. Both (term-H)Fe2(HadtH)(CO)2(dppv)22+ and (term-H)Fe2(adtH)(CO)2(dppv)2+ are highly active electrocatalysts for HER. Catalysis is initiated by reduction of the diferrous center, which induces coupling of the protic ammonium center and the hydride ligand. In contrast, the propanedithiolate (term-H)Fe2(pdt)(CO)2(dppv)2+ is a poor electrocatalyst for HER. Oxidation of H2 has been demonstrated, starting with models for the oxidized state (“Hox”), for example, Fe2(adtH)(CO)3(dppv)(PMe3)+. Featuring a distorted Fe(II)Fe(I) center, this Hox model reacts slowly with high pressures of H2 to give (μ-H)Fe2(adtH)(CO)3(dppv)(PMe3)+. Highlighting the role of the proton relay, the propanedithiolate Fe2(pdt)(CO)3(dppv)(PMe3)+ is unreactive toward H2. The Hox-model + H2 reaction is accelerated in the presence of ferrocenium salts, which simulate the role of the attached 4Fe–4S cluster. The redox-complemented complex Fe2(adtBn)(CO)3(dppv)(FcP*) n+ catalyzes both proton reduction and hydrogen oxidation (FcP* = (C5Me5)Fe(C5Me4CH2PEt2)).
Virtually all organosulfur compounds react with Fe(0) carbonyls to give the title complexes. These reactions are reviewed in light of major advances over the past few decades, spurred by interest in ...Fe2(μ-SR)2(CO) x centers at the active sites of the FeFe-hydrogenase enzymes. The most useful synthetic route to Fe2(μ-SR)2(CO)6 involves the reaction of thiols with Fe2(CO)9 and Fe3(CO)12. Such reactions can proceed via mono-, di-, and triiron intermediates. The reactivity of Fe(0) carbonyls toward thiols is highly chemoselective, and the resulting dithiolato complexes are fairly rugged. Thus, many complexes tolerate further synthetic elaboration directed at the organic substituents. A second major route involves alkylation of Fe2(μ-S2)(CO)6, Fe2(μ-SH)2(CO)6, and Li2Fe2(μ-S)2(CO)6. This approach is especially useful for azadithiolates Fe2(μ-SCH2)2NR(CO)6. Elaborate complexes arise via addition of the FeSH group to electrophilic alkenes, alkynes, and carbonyls. Although the first example of Fe2(μ-SR)2(CO)6 was prepared from ferrous reagents, ferrous compounds are infrequently used, although the Fe(II)(SR)2 + Fe(0) condensation reaction is promising. Almost invariably low-yielding, the reaction of Fe3(CO)12, S8, and a variety of unsaturated substrates results in C–H activation, affording otherwise inaccessible derivatives. Thiones and related CS-containing reagents are highly reactive toward Fe(0), often giving complexes derived from substituted methanedithiolates and C–H activation.
Human–Robot Interaction Sheridan, Thomas B.
Human factors,
06/2016, Letnik:
58, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Objective:
The current status of human–robot interaction (HRI) is reviewed, and key current research challenges for the human factors community are described.
Background:
Robots have evolved from ...continuous human-controlled master–slave servomechanisms for handling nuclear waste to a broad range of robots incorporating artificial intelligence for many applications and under human supervisory control.
Methods:
This mini-review describes HRI developments in four application areas and what are the challenges for human factors research.
Results:
In addition to a plethora of research papers, evidence of success is manifest in live demonstrations of robot capability under various forms of human control.
Conclusions:
HRI is a rapidly evolving field. Specialized robots under human teleoperation have proven successful in hazardous environments and medical application, as have specialized telerobots under human supervisory control for space and repetitive industrial tasks. Research in areas of self-driving cars, intimate collaboration with humans in manipulation tasks, human control of humanoid robots for hazardous environments, and social interaction with robots is at initial stages. The efficacy of humanoid general-purpose robots has yet to be proven.
Applications:
HRI is now applied in almost all robot tasks, including manufacturing, space, aviation, undersea, surgery, rehabilitation, agriculture, education, package fetch and delivery, policing, and military operations.
This paper is concerned with the parameter estimation of a general class of nonlinear dynamic systems in state-space form. More specifically, a Maximum Likelihood (ML) framework is employed and an ...Expectation Maximisation (EM) algorithm is derived to compute these ML estimates. The Expectation (E) step involves solving a nonlinear state estimation problem, where the smoothed estimates of the states are required. This problem lends itself perfectly to the particle smoother, which provides arbitrarily good estimates. The maximisation (M) step is solved using standard techniques from numerical optimisation theory. Simulation examples demonstrate the efficacy of our proposed solution.
Three in one: New reagents are needed to generate liquid fuels from biomass, but the reagents must serve multiple roles. For the conversion of fructose into the title compound 1, formic acid serves ...three roles: assists in the isomerization/dehydration, serves as an H2 source for hydrogenation, and helps deoxygenate the alcohol functional groups.
Institutional Work Lawrence, Thomas B; Suddaby, Roy; Leca, Bernard
07/2009
eBook
The 'institutional' approach to organizational research has shown how enduring features of social life - such as marriage and bureaucracy - act as mechanisms of social control. Such approaches have ...traditionally focused attention on the relationships between organizations and the fields in which they operate, providing strong accounts of the processes through which institutions govern action. In contrast, the study of institutional work reorients these traditional concerns, shifting the focus to understanding how action affects institutions. This book sets a research agenda within the field of institutional work by analyzing the ways in which individuals, groups, and organizations work to create, maintain, and disrupt the institutions that structure their lives. Through a series of essays and case studies, it explores the conceptual core of institutional work, identifies institutional work strategies, provides exemplars for future empirical research, and embeds the concept within broader sociological debates and ideas.
Aging is an inherently stochastic process, and its hallmark is heterogeneity between organisms, cell types, and clonal populations, even in identical environments. The replicative lifespan of primary ...human cells is telomere dependent; however, its heterogeneity is not understood. We show that mitochondrial superoxide production increases with replicative age in human fibroblasts despite an adaptive UCP-2-dependent mitochondrial uncoupling. This mitochondrial dysfunction is accompanied by compromised Ca(2+)i homeostasis and other indicators of a retrograde response in senescent cells. Replicative senescence of human fibroblasts is delayed by mild mitochondrial uncoupling. Uncoupling reduces mitochondrial superoxide generation, slows down telomere shortening, and delays formation of telomeric gamma-H2A.X foci. This indicates mitochondrial production of reactive oxygen species (ROS) as one of the causes of replicative senescence. By sorting early senescent (SES) cells from young proliferating fibroblast cultures, we show that SES cells have higher ROS levels, dysfunctional mitochondria, shorter telomeres, and telomeric gamma-H2A.X foci. We propose that mitochondrial ROS is a major determinant of telomere-dependent senescence at the single-cell level that is responsible for cell-to-cell variation in replicative lifespan.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The commensal microbiota is a major regulator of the immune system. The majority of commensal bacteria inhabit the gastrointestinal tract and are known to regulate local mucosal defenses against ...intestinal pathogens. There is growing appreciation that the commensal microbiota also regulates immune responses at extraintestinal sites. Currently, however, it is unclear how this influences host defenses against bacterial infection outside the intestine. Microbiota depletion caused significant defects in the early innate response to lung infection by the major human pathogen Klebsiella pneumoniae. After microbiota depletion, early clearance of K. pneumoniae was impaired, and this could be rescued by administration of bacterial Nod-like receptor (NLR) ligands (the NOD1 ligand MurNAcTri(DAP) and NOD2 ligand muramyl dipeptide MDP) but not bacterial Toll-like receptor (TLR) ligands. Importantly, NLR ligands from the gastrointestinal, but not upper respiratory, tract rescued host defenses in the lung. Defects in early innate immunity were found to be due to reduced reactive oxygen species-mediated killing of bacteria by alveolar macrophages. These data show that bacterial signals from the intestine have a profound influence on establishing the levels of antibacterial defenses in distal tissues.
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