The origin of Sr segregation at La1-xSrxMnO3 surfaces

A uniform distribution of La and Sr in lanthanum-strontium manganites would lead to charged crystal planes, a charged surface, and arbitrarily large surface energy for a bulk crystal. This divergent energy can be eliminated by depleting the La concentration near the surface. Assuming an exponential form for segregation suggested by experiment, the total electrostatic energy is calculated, depending only upon the decay length and on an effective charge Z* associated with the La ion. It is found to be lower in energy than neutralization of the surface by changing Mn charge states, previously expected, and lower than simply readjusting the La concentration in the surface plane. The actual decay length obtained by minimizing this electrostatic energy is shorter than that observed. The extension of this mechanism to segregation near the surface in other systems is discussed

Feeling cold is contagious

Seeing someone plunge into an ice-cold bath induces feelings of cold. However, it was recently demonstrated that viewing another's skin temperature change also induces a small congruent temperature change in the observer. This synchronization suggests top-down influences on peripheral temperature regulation mechanisms and lends supports to somatic-simulation theories of inter-subjectivity

Relational Identities and Other-Than-Human Agency in Archaeology

Relational Identities and Other-than-Human Agency in Archaeology explores the benefits and consequences of archaeological theorizing on and interpretation of the social agency of nonhumans as relational beings capable of producing change in the world. The volume cross-examines traditional understanding of agency and personhood, presenting a globally diverse set of case studies that cover a range of cultural, geographical, and historical contexts. Agency (the ability to act) and personhood (the reciprocal qualities of relational beings) have traditionally been strictly assigned to humans. In case studies from Ghana to Australia to the British Isles and Mesoamerica, contributors to this volume demonstrate that objects, animals, locations, and other nonhuman actors also potentially share this ontological status and are capable of instigating events and enacting change. This kind of other-than-human agency is not a one-way transaction of cause to effect but requires an appropriate form of reciprocal engagement indicative of relational personhood, which in these cases, left material traces detectable in the archaeological record. Modern dualist ontologies separating objects from subjects and the animate from the inanimate obscure our understanding of the roles that other-than-human agents played in past societies. Relational Identities and Other-than-Human Agency in Archaeology challenges this essentialist binary perspective. Contributors in this volume show that intersubjective (inherently social) ways of being are a fundamental and indispensable condition of all personhood and move the debate in posthumanist scholarship beyond the polarizing dichotomies of relational versus bounded types of persons. In this way, the book makes a significant contribution to theory and interpretation of personhood and other-than-human agency in archaeology.https://cupola.gettysburg.edu/books/1141/thumbnail.jp

Different cation-protonation patterns in mol-ecular salts of unsymmetrical dimethyhydrazine : C2H9N2·Br and C2H9N2·H2PO3

Acknowledgements We thank the EPSRC National Crystallography Service (University of Southampton) for the data collections.Peer reviewedPublisher PD

Experimental determination of layer cloud edge charging from cosmic ray ionisation

The cloud-air transition zone at stratiform cloud edges is an electrically active region where droplet charging has been predicted. Cloud edge droplet charging is expected from vertical flow of cosmic ray generated atmospheric ions in the global electric circuit. Experimental confirmation of stratiform cloud edge electrification is presented here, through charge and droplet measurements made within an extensive layer of supercooled stratiform cloud, using a specially designed electrostatic sensor. Negative space charge up to 35 pC m−3 was found in a thin (<100 m) layer at the lower cloud boundary associated with the clear air-cloud conductivity gradient, agreeing closely with space charge predicted from the measured droplet concentration using ion-aerosol theory. Such charge levels carried by droplets are sufficient to influence collision processes between cloud droplets

Ultrastructural alteration of mouse lung by prolonged exposure to mixtures of helium and oxygen

Observed changes consist mainly of blebbing of capillary endothelium and alveolar epithelium, which is quite possibly indicative of cellular edema; also, there can be observed highly-convoluted basement membrane, alveolar debris, and increased numbers of platelets

Naturally Occurring Markets and Exogenous Laboratory Experiments: A Case Study of the Winner's Curse

There has been a dramatic increase in the use of experimental methods in the past two decades. An oft-cited reason for this rise in popularity is that experimental methods provide the necessary control to estimate treatment effects in isolation of other confounding factors. We question the relevance of experimental findings from laboratory settings that abstract from the field context of the task that theory purports to explain. Using common value auction theory as our guide, we identify naturally occurring settings in which one can test the theory. In our treatments the subjects are not picked at random, as in lab experiments with student subjects, but are deliberately identified by their trading roles in the natural field setting. We find that experienced agents bidding in familiar roles do not fall prey to the winner's curse. Yet, when experienced agents are observed bidding in an unfamiliar role, we find that they frequently fall prey to the winner's curse. We conclude that the theory predicts field behavior well when one is able to identify naturally occurring field counterparts to the key theoretical conditions.