Hypervelocity runaways from the Large Magellanic Cloud

We explore the possibility that the observed population of Galactic hypervelocity stars (HVSs) originate as runaway stars from the Large Magellanic Cloud (LMC). Pairing a binary evolution code with an N-body simulation of the interaction of the LMC with the Milky Way, we predict the spatial distribution and kinematics of an LMC runaway population. We find that runaway stars from the LMC can contribute Galactic HVSs at a rate of $3 \times 10^{-6}\;\mathrm{yr}^{-1}$. This is composed of stars at different points of stellar evolution, ranging from the main-sequence to those at the tip of the asymptotic giant branch. We find that the known B-type HVSs have kinematics which are consistent with an LMC origin. There is an additional population of hypervelocity white dwarfs whose progenitors were massive runaway stars. Runaways which are even more massive will themselves go supernova, producing a remnant whose velocity will be modulated by a supernova kick. This latter scenario has some exotic consequences, such as pulsars and supernovae far from star-forming regions, and a small rate of microlensing from compact sources around the halo of the LMC.Comment: MNRAS, in pres

Do Attitudes Towards Corruption Differ Across Cultures? Experimental Evidence from Australia, India, Indonesia andSingapore

This paper examines cultural differences in attitudes towards corruption by analysing individual-decision making in a corrupt experimental environment. Attitudes towards corruption play a critical role in the persistence of corruption. Our experiments differentiate between the incentives to engage in corrupt behaviour and the incentives to punish corrupt behaviour and allow us to explore whether, in environments characterized by lower levels of corruption, there is both a lower propensity to engage in corrupt behaviour and a higher propensity to punish corrupt behaviour. Based on experiments run in Australia (Melbourne), India (Delhi), Indonesia (Jakarta) and Singapore, we find that there is more variation in the propensities to punish corrupt behaviour than in the propensities to engage in corrupt behaviour across cultures. The results reveal that the subjects in India exhibit a higher tolerance towards corruption than the subjects in Australia while the subjects in Indonesia behave similarly to those in Australia. The subjects in Singapore have a higher propensity to engage in corruption than the subjects in Australia. We also vary our experimental design to examine the impact of a more effective punishment system and the effect of the perceived cost of bribery.Corruption, Experiments, Punishment, Cultural Analysis

A hypervelocity star with a Magellanic origin

Using proper motion measurements from Gaia DR2, we probe the origin of 26 previously known hypervelocity stars (HVSs) around the Milky Way. We find that a significant fraction of these stars have a high probability of originating close to the Milky Way centre, but there is one obvious outlier. HVS3 is highly likely to be coming almost from the centre of the Large Magellanic Cloud (LMC). During its closest approach, $21.1^{+6.1}_{-4.6}$ Myr ago, it had a relative velocity of $870^{+69}_{-66}$ kms$^{-1}$ with respect to the LMC. This large kick velocity is only consistent with the Hills mechanism, requiring a massive black hole at the centre of the LMC. This provides strong direct evidence that the LMC itself harbours a massive black hole of at least $4\times 10^3 -10^4 M_\odot$.Comment: 7 pages, 9 figures. Submitted to MNRAS. Comments welcome

Computational Investigation of Structure-Function Relationship in Fluorine-Functionalized MOFs for PFOA Capture from Water

A strategy that can be used to develop metal-organic frameworks (MOFs) to capture per- and poly-fluoroalkyl substances (PFAS) from water is functionalizing them with fluorine moieties. We investigated different fluorine-functionalization strategies and their performance in removing PFAS from water using molecular simulations. Perfluorooctanoic acid (PFOA), one of the most widely encountered PFAS in water sources, was used as the probe molecule. Our simulations show that fluorine functionalization by incorporating fluorinated anions as bridging ligands in MOFs creates additional binding sites for PFOA; however, the same sites also attract water molecules, which casts doubt on their potential use. In contrast, trifluoromethyl or fluorine substitution of the MOF ligands results in higher hydrophobicity. However, the pores fluorinated with this method should have the optimum size to accommodate PFOA. Likewise, post-synthetic fluorine functionalization of MOFs through grafting of perfluorinated alkanes showed increased PFOA affinity. Fluorine-functionalized MOFs with high hydrophobicity and optimized pore sizes can effectively capture PFOA from water at very low concentrations of PFOA

Models of Distorted and Evolving Dark Matter Halos

We investigate the ability of basis function expansions to reproduce the evolution of a Milky Way-like dark matter halo, extracted from a cosmological zoom-in simulation. For each snapshot, the density of the halo is reduced to a basis function expansion, with interpolation used to recreate the evolution between snapshots. The angular variation of the halo density is described by spherical harmonics, and the radial variation either by biorthonormal basis functions adapted to handle truncated haloes or by splines. High fidelity orbit reconstructions are attainable using either method with similar computational expense. We quantify how the error in the reconstructed orbits varies with expansion order and snapshot spacing. Despite the many possible biorthonormal expansions, it is hard to beat a conventional Hernquist-Ostriker expansion with a moderate number of terms ($\gtrsim15$ radial and $\gtrsim6$ angular). As two applications of the developed machinery, we assess the impact of the time-dependence of the potential on (i) the orbits of Milky Way satellites, and (ii) planes of satellites as observed in the Milky Way and other nearby galaxies. Time evolution over the last 5 Gyr introduces an uncertainty in the Milky Way satellites' orbital parameters of $\sim 15$ per cent, comparable to that induced by the observational errors or the uncertainty in the present-day Milky Way potential. On average, planes of satellites grow at similar rates in evolving and time-independent potentials. There can be more, or less, growth in the plane's thickness, if the plane becomes less, or more, aligned with the major or minor axis of the evolving halo.Comment: MNRAS, submitte

Rho primes in analyzing e+e- annihilation, MARK III, LASS and ARGUS data

The results of an analysis are presented of some recent data on the reactions $e^+e^-\to\pi^+\pi^-\pi^+\pi^-$, $e^+e^-\to\pi^+\pi^-\pi^0\pi^0$ with the subtracted $\omega\pi^0$ events, $e^+e^-\to\omega\pi^0$, $e^+e^-\to\eta \pi^+\pi^-$, $e^+e^-\to\pi^+\pi^-$, $K^-p\to\pi^+\pi^-\Lambda$, the decays $J/\psi\to\pi^+\pi^-\pi^0$, $tau^-\to\nu_tau\pi^+\pi^-\pi^-\pi^0$ $tau^-\to\nu_\tau\omega\pi^-$, upon taking into account both the strong energy dependence of the partial widths on energy and the previously neglected mixing of the $\rho$ type resonances. The above effects are shown to exert an essential influence on the specific values of masses and coupling constants of heavy resonances and hence are necessary to be accounted for in establishing their true nature.Comment: 20 pages, ReVTeX, 9 Postscript figures As compared to hep-ph/9607398, new material concerning the analysis of the ARGUS data on the tau decays into four pion hadronic states is adde

Yangian Symmetry at Two Loops for the su(2|1) Sector of N=4 SYM

We present the perturbative Yangian symmetry at next-to-leading order in the su(2|1) sector of planar N=4 SYM. Just like the ordinary symmetry generators, the bi-local Yangian charges receive corrections acting on several neighboring sites. We confirm that the bi-local Yangian charges satisfy the necessary conditions: they transform in the adjoint of su(2|1), they commute with the dilatation generator, and they satisfy the Serre relations. This proves that the sector is integrable at two loops.Comment: 13 pages, v2: minor correction

Size-controlled conformal nanofabrication of biotemplated three-dimensional TiO2 and ZnO nanonetworks

Cataloged from PDF version of article.A solvent-free fabrication of TiO2 and ZnO nanonetworks is demonstrated by using supramolecular nanotemplates with high coating conformity, uniformity, and atomic scale size control. Deposition of TiO2 and ZnO on three-dimensional nanofibrous network template is accomplished. Ultrafine control over nanotube diameter allows robust and systematic evaluation of the electrochemical properties of TiO2 and ZnO nanonetworks in terms of size-function relationship. We observe hypsochromic shift in UV absorbance maxima correlated with decrease in wall thickness of the nanotubes. Photocatalytic activities of anatase TiO2 and hexagonal wurtzite ZnO nanonetworks are found to be dependent on both the wall thickness and total surface area per unit of mass. Wall thickness has effect on photoexcitation properties of both TiO2 and ZnO due to band gap energies and total surface area per unit of mass. The present work is a successful example that concentrates on nanofabrication of intact three-dimensional semiconductor nanonetworks with controlled band gap energies

Structured star formation in the Magellanic inter-Cloud region

We use a new contiguous imaging survey conducted using the Dark Energy Camera to investigate the distribution and properties of young stellar populations in the Magellanic inter-Cloud region. These young stars are strongly spatially clustered, forming a narrow chain of low-mass associations that trace the densest H I gas in the Magellanic Bridge and extend, in projection, from the SMC to the outer disc of the LMC. The associations in our survey footprint have ages ≲ 30 Myr, masses in the range ∼100-1200 M⊙ and very diffuse structures with half-light radii of up to ∼100 pc. The two most populous are strongly elliptical and aligned to ≈10°, with the axis joining the centres of the LMC and the SMC. These observations strongly suggest that the young inter-Cloud populations formed in situ, likely due to the compression of gas stripped during the most recent close LMC-SMC encounter. The associations lie at distances intermediate between the two Clouds, and we find no evidence for a substantial distance gradient across the imaged area. Finally, we identify a vast shell of young stars surrounding a central association, that is spatially coincident with a low column density bubble in the H I distribution. The properties of this structure are consistent with a scenario where stellar winds and supernova explosions from massive stars in the central cluster swept up the ambient gas into a shell, triggering a new burst of star formation. This is a prime location for studying stellar feedback in a relatively isolated environment

Bonus versus penalty: how robust are the effects of contract framing?

We study the relative effectiveness of contracts that are framed either in terms of bonuses or penalties. In one set of treatments subjects know at the time of effort provision whether they have achieved the bonus / avoided the penalty. In another set of treatments subjects only learn the success of their performance at the end of the task. We fail to observe a contract framing effect in either condition: effort provision is statistically indistinguishable under bonus and penalty contracts