Correlations of mesospheric winds with subtle motion of the Arctic polar vortex

This paper investigates the relationship between high latitude upper mesospheric winds and the state of the stratospheric polar vortex in the absence of major sudden stratospheric warmings. A ground based Michelson Interferometer stationed at Resolute Bay (74°43' N, 94°58' W) in the Canadian High Arctic is used to measure mesopause region neutral winds using the hydroxyl (OH) Meinel-band airglow emission (central altitude of ~85 km). These observed winds are compared to analysis winds in the upper stratosphere during November and December of 1995 and 1996; years characterized as cold, stable polar vortex periods. Correlation of mesopause wind speeds with those from the upper stratosphere is found to be significant for the 1996 season when the polar vortex is subtly displaced off its initial location by a strong Aleutian High. These mesopause winds are observed to lead stratospheric winds by approximately two days with increasing (decreasing) mesospheric winds predictive of decreasing (increasing) stratospheric winds. No statistically significant correlations are found for the 1995 season when there is no such displacement of the polar vortex

The Politics of Post-Qualitative Inquiry: History and Power

In this article, we offer a critical reading of the increasingly popular “post-qualitative” approach to research. We draw on insights from postcolonial theory to offer some provocations about the methodological and conceptual claims made by post-qualitative inquiry. The article considers how post-qualitative inquiry opens up possibilities for post-humanist social research. But, our critical reading of these “new” approaches argues that such research needs to attend to political and historical relations of social power, both in the worlds it constitutes and in the processes of its knowledge production. Without explicit attention to power and history, the (non)representational logics of post-qualitative inquiry risk operating less as “new” mechanisms for generative and subversive post-humanist research and more as processes of closure and erasure: closed-off from the worlds and people being researched

Long-run savings and investment strategy optimization

We focus on automatic strategies to optimize life cycle savings and investment. Classical optimal savings theory establishes that, given the level of risk aversion, a saver would keep the same relative amount invested in risky assets at any given time. We show that, when optimizing lifecycle investment, performance and risk assessment have to take into account the investor's risk aversion and the maximum amount the investor could lose, simultaneously. When risk aversion and maximum possible loss are considered jointly, an optimal savings strategy is obtained, which follows from constant rather than relative absolute risk aversion. This result is fundamental to prove that if risk aversion and the maximum possible loss are both high, then holding a constant amount invested in the risky asset is optimal for a standard lifetime saving/pension process and outperforms some other simple strategies. Performance comparisons are based on downside risk-adjusted equivalence that is used in our illustration

Transverse Shifts in Paraxial Spinoptics

The paraxial approximation of a classical spinning photon is shown to yield an "exotic particle" in the plane transverse to the propagation. The previously proposed and observed position shift between media with different refractive indices is modified when the interface is curved, and there also appears a novel, momentum [direction] shift. The laws of thin lenses are modified accordingly.Comment: 3 pages, no figures. One detail clarified, some misprints corrected and references adde

What’s in a (pseudo)name?: Ethical conundrums for the principles of anonymisation in social media research

Scholars from wide-ranging disciplines are turning to social media platforms as research sites, and as platforms expand their communicative possibilities, they create more spaces for users to enact a multitude of identities. Most platforms allow users to have ‘pseudonymous’ identities; that is, they can engage in practices intended to facilitate nonidentifiable content. But pseudonymity presents a series of unique challenges to the principles of anonymisation in qualitative research. This article explores the slippery nature of dealing with pseudonymous social media users’ personally identifiable data during research, framed around my responses to four questions I was asked when I applied for ethical approval to conduct research with pseudonymous fan communities on social media. The four questions concern: (Q1) changing notions of ‘public’ and ‘private’ forms of data; (Q2) identifying underage and therefore vulnerable participants online; (Q3) changes to the processes of obtaining informed consent from social media users; and (Q4) the risks social media research might bring to those conducting it. This article concludes by calling for qualitative researchers and Ethics Review Boards (ERBs) to engage with institutional ethics review across the duration of a project, or at the very least to advocate for ongoing consent as research progresses, especially for (but certainly not limited to) research involving pseudonymous social media users. The article aims to be useful to other researchers facing similar dilemmas. Indeed, given the popularity of pseudonymity on social media and the growing penetration of platforms across global demographics, a need for ethical discussions of this kind is surely set to increase

Chromatin Profiles of Chromosomally Integrated Human Herpesvirus-6A

Human herpesvirus-6A (HHV-6A) and 6B (HHV-6B) are two closely related betaherpesviruses that are associated with various diseases including seizures and encephalitis. The HHV-6A/B genomes have been shown to be present in an integrated state in the telomeres of latently infected cells. In addition, integration of HHV-6A/B in germ cells has resulted in individuals harboring this inherited chromosomally integrated HHV-6A/B (iciHHV-6) in every cell of their body. Until now, the viral transcriptome and the epigenetic modifications that contribute to the silencing of the integrated virus genome remain elusive. In the current study, we used a patient-derived iciHHV-6A cell line to assess the global viral gene expression profile by RNA-seq, and the chromatin profiles by MNase-seq and ChIP-seq analyses. In addition, we investigated an in vitro generated cell line (293-HHV-6A) that expresses GFP upon the addition of agents commonly used to induce herpesvirus reactivation such as TPA. No viral gene expression including miRNAs was detected from the HHV-6A genomes, indicating that the integrated virus is transcriptionally silent. Intriguingly, upon stimulation of the 293-HHV-6A cell line with TPA, only foreign promoters in the virus genome were activated, while all HHV-6A promoters remained completely silenced. The transcriptional silencing of latent HHV-6A was further supported by MNase-seq results, which demonstrate that the latent viral genome resides in a highly condensed nucleosome-associated state. We further explored the enrichment profiles of histone modifications via ChIP-seq analysis. Our results indicated that the HHV-6 genome is modestly enriched with the repressive histone marks H3K9me3/H3K27me3 and does not possess the active histone modifications H3K27ac/H3K4me3. Overall, these results indicate that HHV-6 genomes reside in a condensed chromatin state, providing insight into the epigenetic mechanisms associated with the silencing of the integrated HHV-6A genome

IMPRESSION – prediction of NMR parameters for 3-dimensional chemical structures using machine learning with near quantum chemical accuracy

The IMPRESSION (Intelligent Machine PREdiction of Shift and Scalar Information Of Nuclei) machine learning system provides an efficient and accurate route to the prediction of NMR parameters from 3-dimensional chemical structures. Here we demonstrate that machine learning predictions, trained on quantum chemical computed values for NMR parameters, are essentially as accurate but computationally much more efficient (tens of milliseconds per molecule) than quantum chemical calculations (hours/days per molecule). Training the machine learning systems on quantum chemical, rather than experimental, data circumvents the need for existence of large, structurally diverse, error-free experimental databases and makes IMPRESSION applicable to solving 3-dimensional problems such as molecular conformation and isomeris

Effect of sting size on the wake of a sphere at subcritical Reynolds numbers

Vortex shedding and turbulent motion in the wake of a sphere that is supported using a streamwise-aligned cylindrical sting are investigated at a subcritical Reynolds number of Re=3800, using high speed particle image velocimetry. The mechanism by which the presence of a sting of increasing diameter relative to the diameter of the sphere influences the wake, in terms of both the small-scale shear instability and the larger wake instability, is explored and brie y compared with the two-dimensional analog of the splitter plate introduced into a cylinder wake. The difficulties associated with obtaining converged statistics, along with the effect of free stream turbulence and sphere vibrations are detailed. An understanding of the mechanism by which the blockage, or interference, arising from the presence of the sting influences cross-wake communication and downstream development is a necessary precursor to studies of active control of the wake using surface actuation on a sting-mounted sphere