Excited-State Dynamics of Pyrimidine DNA Bases Revealed by Ultrafast Vibrational Spectroscopy

Mathematical and Physical Sciences: 3rd Place (The Ohio State University Edward F. Hayes Graduate Research Forum)To better understand the link between light absorption and deleterious DNA photoproducts, the photophysics of DNA bases was investigate with femtosecond mid-IR transient absorption spectroscopy. Markers band for two excited states, a dark singlet state and a triplet state, were found. These marker bands provide insight into the nature and dynamics of the states. The results confirm a model for pyrimidine bases previous proposed based on UV-visible transient absorption measurements. This study provides an important foundation for future investigations of the role of these states in DNA.A five-year embargo was granted for this item

An absorption origin for the soft excess in Seyfert 1 active galactic nuclei

(abridged) The soft excess seen in the X-ray spectra of many high mass accretion rate AGN can be well modelled by reflection from a partially ionised accretion disc. However, the derived parameters are often extreme, both in terms of the underlying spacetime and the reflection geometry, and these models require that the disc is far from hydrostatic equilibrium. An alternative model uses similarly partially ionised, velocity smeared material but seen in absorption, though again the derived velocities are extreme, requiring magnetic driving (in the jet?) rather than a simple line driven disc wind. We find that while both models give comparably good fits to XMM--Newton data, we favour the absorption model as, unlike reflection, all the derived spectral indices are soft. This is as expected by analogy with the correspondingly high mass accretion rate stellar mass black holes. Furthermore, these X-ray spectra are consistent with a one--to--one mapping between AGN type and spectral state, with NLS1's having softer spectra corresponding to the very high state, while the broad line AGN have Gamma~2 as expected for the high/soft state. We also use the simultaneous OM data to derive the ratio of disc to total accretion power which is another tracer of spectral state in X-ray binaries. This does not always show that the disc in NLS1's contributes less than 80 per cent of the total power, as expected for a very high state. We suggest that this is an artifact of the standard disc models used to determine the disc luminosity in our fits. The disc seen in the very high state of black hole binaries is often observed to be distorted from the standard shape, and a similar effect in NLS1's could recover the correspondance between black hole binary spectral state and AGN type.Comment: 12 pages, 12 figures, submitted to MNRA

Effectiveness of a low-frequency sports-specific resistance and plyometric training programme: the case of an elite junior badminton player

This intervention aimed to improve Badminton-specific functional performance of an elite under-19 player (18 years) via a single-weekly resistance and plyometric training (RPT) session for 8-weeks. The athlete’s ‘response-to’ and ‘withdrawal-from’ the RPT were assessed. The athlete (stature: 1.77 m, mass: 81.5 kg) completed the RPT intervention throughout a competitive season. Performance testing was conducted at; baseline, post-intervention (8-weeks) and after withdrawal-from the RPT (16-weeks). Jump height and throwing distance were assessed via countermovement jump (CMJ), standing long-jump (SLJ) and one-arm (1-MBT) and two-arm (2-MBT) medicine-ball throws respectively. Speed and agility were assessed by 5 m and 10 m sprints and ‘sideways’ and ‘four-corner’ tests respectively. A positive change from baseline to post-intervention (8-weeks) was observed in: CMJ (+0.07 m), SLJ (+0.13 m), 1-MBT (+2.25 m) and 2-MBT (+0.26 m). Observed changes in speed and agility were minimal. At the 16-weeks, small declines in CMJ, SLJ, 1-MBT and 2-MBT (0.04 m, 0.04 m, 0.52 m and 0.05 respectively) existed. Small improvements in 5 and 10 m sprint times (-0.12 s to -0.09 s) and side-ways agility were observed (-0.11 s to -0.39 s), possibly explained by conditioning effects of training and competition. An 8-week Badminton-specific RPT programme provided favourable increases in jumps and MB throws. However, such positive changes were not sustained following the withdrawal period

The Luminous, Hard State Can't Be MAD

We present a straightforward argument for why the luminous, hard state of black hole X-ray binaries (BHXRBs) cannot always be associated with a magnetically arrested accretion disc (MAD). It relies on three core premises: 1) that the type-C quasi-periodic oscillation (QPO) is best explained by Lense-Thirring (LT) precession of a tilted, inner, hot flow; 2) that observed optical and infrared (IR) QPOs with the same or lower frequency as the type-C QPO suggest the jet, too, must precess in these systems; and 3) that numerical simulations of MADs show that their strong magnetic fields promote alignment of the disc with the black hole and, thereby, suppress LT precession. If all three premises hold true, then, at least whenever the optical and IR QPOs are observed alongside the type-C QPO, these systems cannot be in the MAD state. Extending the argument further, if the type-C QPO is always associated with LT precession, then it would rule out MADs anytime this timing feature is seen, which covers nearly all BHXRBs when they are in the luminous, hard and hard-intermediate states.Comment: 5 pages, 2 figures, accepted to MNRA

A child’s-eye view of social difference

Children are increasingly the focus of Government policy, and improvement of outcomes for children in disadvantaged areas is a priority. However, little is known about how children see and experience poverty, wealth, and ‘social difference’ in their everyday lives. This report explores their own views, using their terms. A participatory approach was used, which enabled the children to lead the research focus. The report compares the similarities and differences between the findings from the two groups. The study was conducted with 42 children aged between 8 and 13. Of these, 19 were from a disadvantaged housing estate and 23 attended a fee-paying independent school. The children participated in a series of workshops and helped to choose the research methods, which included role play, photography, mapping and ‘draw and write’ techniques. The report will be of interest to researchers and policymakers in the fields of education and child poverty

In vivo visual screen for dopaminergic Rab ⇿ LRRK2-G2019S interactions in Drosophila discriminates Rab10 from Rab3

LRRK2 mutations cause Parkinson’s, but the molecular link from increased kinase activity to pathological neurodegeneration remains undetermined. Previous in vitro assays indicate that LRRK2 substrates include at least 8 Rab GTPases. We have now examined this hypothesis in vivo in a functional, electroretinogram screen, expressing each Rab with/without LRRK2-G2019S in selected Drosophila dopaminergic neurons. Our screen discriminated Rab10 from Rab3. The strongest Rab/LRRK2-G2019S interaction is with Rab10; the weakest with Rab3. Rab10 is expressed in a different set of dopaminergic neurons from Rab3. Thus, anatomical and physiological patterns of Rab10 are related. We conclude that Rab10 is a valid substrate of LRRK2 in dopaminergic neurons in vivo. We propose that variations in Rab expression contribute to differences in the rate of neurodegeneration recorded in different dopaminergic nuclei in Parkinson’s