Exploratory studies of contact angle hysteresis, wetting of solidified rare gases and surface properties of mercury Final report

Contact angle hysteresis, wetting of solidified rare gases, and surface properties of mercur

A Search for Boron in Damped Ly{\alpha} Systems

We present the first systematic study of boron beyond the Local Group. This analysis is performed on a sample of 30 damped Ly{\alpha} systems (DLAs) with strong metal-lines, which are expected to trace the interstellar medium of high z galaxies. We report on two boron detections at > 3{\sigma} significance; one new detection and one confirmation. The ratios of B/O and, for the first time, B/S are compared with previous stellar and interstellar measurements in the Milky Way and Small Magellanic Cloud. The novel comparison with sulphur, which tracks oxygen's abundance, alleviates the uncertainty associated with stellar oxygen measurements. For both detections, the inferred B/S ratio is in excess of the prediction of primary boron production from spallation processes. Possible sources of contamination are discussed, as well as physical effects that could impact the observed ratios. However taken at face value, the implication of these measurements suggest potentially higher cosmic ray fluxes in DLAs. The prospects for future boron detections in other high redshift DLAs to confirm our results is also discussed.Comment: Accepted for publication in MNRAS, 19 pages, 10 figure

Emittance Growth Due To Tune Fluctuations and the Beam-beam interaction

Analytical formulae and computer simulation results are presented for the emittance growth caused by small asymmetries of the beam-beam force, caused by small fluctuations of the phase, small offsets between the beams and fluctuations in the size of the opposite beam

Transverse Beam Dynamics with Noise

The linear transverse beam dynamics perturbed by magnet non-linearities and noise is analysed, using averaging techniques

Concordant cues in faces and voices: testing the backup signal hypothesis

Information from faces and voices combines to provide multimodal signals about a person. Faces and voices may offer redundant, overlapping (backup signals), or complementary information (multiple messages). This article reports two experiments which investigated the extent to which faces and voices deliver concordant information about dimensions of fitness and quality. In Experiment 1, participants rated faces and voices on scales for masculinity/femininity, age, health, height, and weight. The results showed that people make similar judgments from faces and voices, with particularly strong correlations for masculinity/femininity, health, and height. If, as these results suggest, faces and voices constitute backup signals for various dimensions, it is hypothetically possible that people would be able to accurately match novel faces and voices for identity. However, previous investigations into novel face–voice matching offer contradictory results. In Experiment 2, participants saw a face and heard a voice and were required to decide whether the face and voice belonged to the same person. Matching accuracy was significantly above chance level, suggesting that judgments made independently from faces and voices are sufficiently similar that people can match the two. Both sets of results were analyzed using multilevel modeling and are interpreted as being consistent with the backup signal hypothesis

Diffuse Interstellar Bands in z < 0.6 CaII Absorbers

The diffuse interstellar bands (DIBs) probably arise from complex organic molecules whose strength in local galaxies correlates with neutral hydrogen column density, N(HI), and dust reddening, E(B-V). Since CaII absorbers in quasar (QSO) spectra are posited to have high N(HI) and significant E(B-V), they represent promising sites for the detection of DIBs at cosmological distances. Here we present the results from the first search for DIBs in 9 CaII-selected absorbers at 0.07 < z_abs < 0.55. We detect the 5780Ang DIB in one line of sight at z_abs = 0.1556; this is only the second QSO absorber in which a DIB has been detected. Unlike the majority of local DIB sight-lines, both QSO absorbers with detected DIBs show weak 6284Ang absorption compared with the 5780Ang band. This may be indicative of different physical conditions in intermediate redshift QSO absorbers compared with local galaxies. Assuming that local relations between the 5780Ang DIB strength and N(HI) and E(B-V) apply in QSO absorbers, DIB detections and limits can be used to derive N(HI) and E(B-V). For the one absorber in this study with a detected DIB, we derive E(B-V) = 0.23mag and log[N(HI)] >= 20.9, consistent with previous conclusions that CaII systems have high HI column densities and significant reddening. For the remaining 8 CaII-selected absorbers with 5780Ang DIB non-detections, we derive E(B-V) upper limits of 0.1-0.3mag.Comment: 5 pages, 2 figures. Accepted to MNRAS Letter

Hydrodynamic Simulation of Supernova Remnants Including Efficient Particle Acceleration

A number of supernova remnants (SNRs) show nonthermal X-rays assumed to be synchrotron emission from shock accelerated TeV electrons. The existence of these TeV electrons strongly suggests that the shocks in SNRs are sources of galactic cosmic rays (CRs). In addition, there is convincing evidence from broad-band studies of individual SNRs and elsewhere that the particle acceleration process in SNRs can be efficient and nonlinear. If SNR shocks are efficient particle accelerators, the production of CRs impacts the thermal properties of the shock heated, X-ray emitting gas and the SNR evolution. We report on a technique that couples nonlinear diffusive shock acceleration, including the backreaction of the accelerated particles on the structure of the forward and reverse shocks, with a hydrodynamic simulation of SNR evolution. Compared to models which ignore CRs, the most important hydrodynamical effects of placing a significant fraction of shock energy into CRs are larger shock compression ratios and lower temperatures in the shocked gas. We compare our results, which use an approximate description of the acceleration process, with a more complete model where the full CR transport equations are solved (i.e., Berezhko et al., 2002), and find excellent agreement for the CR spectrum summed over the SNR lifetime and the evolving shock compression ratio. The importance of the coupling between particle acceleration and SNR dynamics for the interpretation of broad-band continuum and thermal X-ray observations is discussed.Comment: Accepted for publication in A & A; 14 pages including 11 figure

The signature of dissipation in the mass-size relation: are bulges simply spheroids wrapped in a disc?

The relation between the stellar mass and size of a galaxy's structural subcomponents, such as discs and spheroids, is a powerful way to understand the processes involved in their formation. Using very large catalogues of photometric bulge+disc structural decompositions and stellar masses from the Sloan Digital Sky Survey Data Release Seven, we carefully define two large subsamples of spheroids in a quantitative manner such that both samples share similar characteristics with one important exception: the 'bulges' are embedded in a disc and the 'pure spheroids' are galaxies with a single structural component. Our bulge and pure spheroid subsample sizes are 76,012 and 171,243 respectively. Above a stellar mass of ~$10^{10}$ M$_{\odot}$, the mass-size relations of both subsamples are parallel to one another and are close to lines of constant surface mass density. However, the relations are offset by a factor of 1.4, which may be explained by the dominance of dissipation in their formation processes. Whereas the size-mass relation of bulges in discs is consistent with gas-rich mergers, pure spheroids appear to have been formed via a combination of 'dry' and 'wet' mergers.Comment: Accepted for publication in MNRAS, 6 pages, 3 figure