Geological mapping of the Hokusai (H05) quadrangle of Mercury: Status update

[Introduction] MESSENGER data are being used to construct ~1:3M scale quadrangle geological maps of Mercury. Here, we present our progress mapping the Hokusai (H05) quadrangle

Post-deposition (and ongoing?) modification of Caloris ejecta blocks

Mercury’s circum-Caloris region hosts numerous kilometer-scale knobs. If these land-forms, peculiar to Caloris, are its ejecta, then they can provide insight into the deep materials of the planet

Constructional Volcanic Edifices on Mercury: Candidates and Hypotheses of Formation

Mercury, a planet with a predominantly volcanic crust, has perplexingly few, if any, constructional volcanic edifices, despite their common occurrence on other solar system bodies with volcanic histories. Using image and topographical data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, we describe two small (< 15 km‐diameter) prominences with shallow summit depressions associated with volcanically flooded impact features. We offer both volcanic and impact‐related interpretations for their formation, and then compare these landforms with volcanic features on Earth and the Moon. Though we cannot definitively conclude that these landforms are volcanic, the paucity of constructional volcanic edifices on Mercury is intriguing in itself. We suggest that this lack is because volcanic eruptions with sufficiently low eruption volumes, rates, and flow lengths, suitable for edifice construction, were highly spatiotemporally restricted during Mercury's geological history. We suggest that volcanic edifices may preferentially occur in association with late‐stage, post‐impact effusive volcanic deposits. The ESA/JAXA BepiColombo mission to Mercury will be able to investigate further our candidate volcanic edifices, search for other, as‐yet unrecognized edifices beneath the detection limits of MESSENGER data, and test our hypothesis that edifice construction is favored by late‐stage, low‐volume effusive eruptions

A comprehensive survey of hearing questionnaires: how many are there, what do they measure, and how have they been validated?

The self-report questionnaire is a popular tool for measuring outcomes in trials of interventions for hearing impairment. Many have been designed over the last fifty years, and there is no single standard questionnaire that is widely accepted and used. We felt it would be a valuable resource to have a comprehensive collection of all adult hearing-loss questionnaires (excluding those wholly devoted to tinnitus, children, or cochlear implants) and to survey their degree of validation. We collated copies of every published hearing difficulty questionnaire that we could find. The search was primarily done by iterative reference searching. Questionnaire topics were obtained by mapping the text of each questionnaire onto a set of categories; reports of validation methods were taken from the primary paper(s) on each questionnaire. In total we found 139 hearing-specific questionnaires (though many others were found that were primarily about something else). Though not formally systematic, we believe that we have included every questionnaire that is important, most of those of some notice, and a fair fraction of those obscure. We classified 111 as “primary” and the remaining 28 as “contractions”, being shortened versions of a primary without any new questions. In total, there were 3618 items across all the primary questionnaires. The median number of items per questionnaire was 20; the maximum was 158. Across all items, about one third were concerned with the person’s own hearing, another third with the repercussions of it, and about a quarter with hearing aids. There was a wide range in validation methods, from only using items chosen statistically from wider pools and with formal validation against independent measures of clinical outcomes, to just reporting a correlation with an audiogram measure of hearing loss. The “state of play” of the field of hearing questionnaires will be discussed

High throughput sequencing in acute lymphoblastic leukemia reveals clonal architecture of central nervous system and bone marrow compartments

No abstract available

Evidence for the Strongest Version of the 4d a-Theorem, via a-Maximization Along RG Flows

In earlier work, we (KI and BW) gave a two line "almost proof" (for supersymmetric RG flows) of the weakest form of the conjectured 4d a-theorem, that a_{IR}<a_{UV}, using our result that the exact superconformal R-symmetry of 4d SCFTs maximizes a=3Tr R^3-Tr R. The proof was incomplete because of two identified loopholes: theories with accidental symmetries, and the fact that it's only a local maximum of \it{a}. Here we discuss and extend a proposal of Kutasov (which helps close the latter loophole) in which a-maximization is generalized away from the endpoints of the RG flow, with Lagrange multipliers that are conjectured to be identified with the running coupling constants. a-maximization then yields a monotonically decreasing "a-function" along the RG flow to the IR. As we discuss, this proposal in fact suggests the strongest version of the a-theorem: that 4d RG flows are gradient flows of an a-function, with positive definite metric. In the perturbative limit, the RG flow metric thus obtained is shown to agree precisely with that found by very different computations by Osborn and collaborators. As examples, we discuss a new class of 4d SCFTs, along with their dual descriptions and IR phases, obtained from SQCD by coupling some of the flavors to added singlets.Comment: 36 pages, 6 figures. v2: added referenc

The Exact Superconformal R-symmetry Minimizes τRR\tau_{RR}

We present a new, general constraint which, in principle, determines the superconformal $U(1)_R$ symmetry of 4d $\N =1$ SCFTs, and also 3d $\N =2$ SCFTs. Among all possibilities, the superconformal $U(1)_R$ is that which minimizes the coefficient, $\tau_{RR}$, of its two-point function. Equivalently, the superconformal $U(1)_R$ is the unique one with vanishing two-point function with every non-R flavor symmetry. For 4d $\N =1$ SCFTs, $\tau_{RR}$ minimization gives an alternative to a-maximization. $\tau_{RR}$ minimization also applies in 3d, where no condition for determining the superconformal $U(1)_R$ had been previously known. Unfortunately, this constraint seems impractical to implement for interacting field theories. But it can be readily implemented in the AdS geometry for SCFTs with AdS duals.Comment: 18 page

MESSENGER Observations of Volcanism on Mercury: From Hokusai Quadrangle Down to Small Cones

This thesis addresses the regional geology of the planet Mercury as seen by the MErcury Surface, Space ENvironment, and Ranging (MESSENGER) mission. I aimed to investigate the existence and origin of volcanic photogeological units and landforms on Mercury not mappable at the global scale. Using MESSENGER images, I have made the first 1:3,000,000-scale geological map of the Hokusai (H05) quadrangle. My map shows that this region has a similar history of effusive volcanism to the rest of Mercury, with widespread plains formation having given way to lower volume effusions that were ultimately confined to impact craters. However, I found that H05 contains plains that do not conform to the definitions of the two globally recognised plains units on Mercury, intercrater plains and smooth plains, which are thought to be volcanic in origin. I mapped such plains as intermediate plains, due to their intermediate roughness between the two global plains types, and I suggest that they represent incompletely volcanically resurfaced regions of Mercury’s crust. The apparent absence of even small volcanic constructs on Mercury, emphasised to me during my mapping of the volcanologically diverse H05, led me to search for such constructs across Mercury. The two candidates I found, if volcanic, were probably built by low-volume eruptions that were uncharacteristic of most of Mercury’s volcanic history. During my search for volcanoes, I investigated the circum-Caloris knobs. Through mapping, photogeological observations and topographic measurements, I have shown that these small (<15 km across) landforms are not volcanoes, but instead are Caloris ejecta blocks that have undergone long-lived, or even recent, modification into cones. My observations suggest that volatile-loss might have driven modification of the blocks. The intermediate plains, candidate volcanoes, and circum-Caloris knobs will be important targets for the BepiColombo mission, which launched during the preparation of this thesis

Preliminary findings from geological mapping of the Hokusai (H5) quadrangle of Mercury

Quadrangle geological maps from Mariner 10 flybys only cover 45% of the surface of Mercury at 1:5M scale. This study will use orbital data from NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) satellite, to produce a map at ~1:2M scale of the Hokusai quadrangle (0–90° E; 22.5–66° N), which is in the hemisphere unmapped by Mariner 10. This geological map will aim to be compatible with other new quadrangle maps and to complement a global map now in progress

Pluralism and social epistemology in economics

Economics plays a significant role in decision-making in contemporary western societies, but its role is increasingly questioned. A recurring topic among the challenges raised by critics is that economics as a discipline lacks sufficient pluralism. That is, it fails to enable, encourage, and respect the use of different ontologies, methodologies, theories, and/or schools of thought to study economic reality. Has this been a productive critique? Does talk about pluralism help identify genuine problems in the discipline? Pluralism in economics could draw support from the current consensus in philosophy that pluralism in science is a good thing. I argue, however, that the claim that economic research is insufficiently pluralist is unlikely to convince economists who believe economics is already pluralist enough and that it does not offer unambiguous recommendations for change. This is because there are too many legitimate ways to interpret how pluralism maps to practice. There are numerous variables that pluralist ideals might focus on—the things that they seek multiple rather than one of—and different interpretations of how many of those variables economics has in practice. Yet, as I go on to argue, this does not mean that talk of pluralism is entirely beside the point, since the reasons pluralists offer for their ideals do help to identify genuine problems in economics. The social epistemic strategies that arguments for pluralism recommend point us to three concrete issues in the way economic research is organised: gender imbalances, a steep internal hierarchy, and a dismissive attitude to outsiders. I show that economic research could be more progressive, representative of the interests of those in society, accepted, and legitimate and less likely to fall into bias if the discipline alleviated its gender imbalances, if it were less hierarchical, and if it had a healthier relationship with outsiders. In chapter 1, I outline the debate about pluralism in economics and explain how my thesis utilises a novel approach to social epistemology to offer a way out of the impasse in which that the debate presently resides. In chapter 2, I explain the different philosophical arguments for pluralism in science and categorise them using the variables they focus on and the reasons they give for pluralism. In chapter 3, I argue that interpreting pluralism as a particular arrangement of variables for economics to attain does not lead to unambiguous recommendations for change because it leaves too much open. Yet, I go on to argue, in chapter 4, that drawing on the reasons for pluralism can provide a set of heuristics for piecemeal evaluations of the social epistemic practices in economics. In chapters 5, 6, and 7, I apply these heuristics to economics. I provide evidence that [a] women are outnumbered in economics and face an adverse environment in the discipline, that [b] economics is steeply hierarchical, and that [c] economists form an in-group that assumes superiority and frequently dismisses outside voices. I argue that these three features of economic research block avenues for productive forms of feedback (mechanisms that help to challenge, justify, and refine scientific knowledge), block the interests of certain perspectives being heard, and block public scrutiny of the decisions made by economists.Funded by the Cambridge Arts and Humanities Research Council doctoral training centre