Relationships and events: towards a general theory of reification and truthmaking.

We propose a novel ontological analysis of relations and relationships based on a re-visitation of a classic problem in the practice of knowledge repre- sentation and conceptual modeling, namely relationship reification. Our idea is that a relation holds in virtue of a relationship's existence. Relationships are therefore truthmakers of relations. In this paper we present a general theory or reification and truthmaking, and discuss the interplay between events and rela- tionships, suggesting that relationships are the focus of events, which emerge from the context (the scene) they occur in

Surface forces in particle technology: Wet systems

Surface forces play a fundamental role in particle processing as they control the stability, adhesion, friction and rheology of particulate systems and information on all of these can be obtained from an analysis of the normal forces measured between particles. Therefore particle processing at all stages can be informed by knowledge of the forces between the constituent particles. For wet particles systems, the interaction forces between two particles can rarely be predicted from theory, but rather requires experimentation or direct measurement. This requires that the surfaces used have the same as surface properties as the particles. In practice this is rarely possible, as surface force measurements require surfaces with extremely low roughness and precise geometry and the majority of materials do not conform to these requirements. To address these challenges we produce surfaces of low roughness and controlled chemistry using Atomic Layer Deposition (ALD) and are developing methods to calculate and understand the influence of surface roughness on the measured forces. Here we report the forces between hafnia surfaces produced by ALD and show that like ALD produced titania surfaces and silica surfaces, the expected van der Waals forces at high pH are not manifest, suggesting that most real surfaces have unexpectedly repulsive surface forces at high pH and small separations. This will fundamentally alter how these particulate systems behave when being processed, reducing the adhesion and the friction and enhancing the stability compared to the expected interaction from DLVO theory

From Oxford to Bristol and Back: The Invention of Scientific Wildlife Television

In the 1960s, two scientists from Oxford University, Niko Tinbergen and Gerald Thompson, began using film as part of their scientific practice. The BBC’s Natural History Unit (NHU) in Bristol quickly got wind of their work and started collaborating with them to develop a new approach to wildlife television making. Tinbergen, the founder of ethology, brought intellectual foundations to it, creating, with Christopher Parsons, stories of wildlife informed by the theory of evolution. Thompson provided a technological edge which enabled the Bristol NHU producers to bring a new perspective to the subject matter they were showing in their programmes. The two collaborations also led them to further define their identity as experts in wildlife television making

Electron-hole imbalance in superconductor-normal metal mesoscopic structures

We analysed the electron-hole or, in another words, branch imbalance (BI) and the related electric potential $V_{imb}$ which may arise in a mesoscopic superconductor/normal metal (S/N) structure under non-equilibrium conditions in the presence of a supercurrent. Non-equilibrium conditions can be created in different ways: a) a quasiparticle current flowing between the N reservoirs; b) a temperature gradient between the N reservoirs and no quasiparticle current. It is shown that the voltage $V_{imb}$ oscillates with the phase difference $\phi$. In a cross-geometry structure the voltage $V_{imb}$ arises in the vertical branch and affects the conditions for a transition into the $\pi$-state.Comment: 6 pages, 5 figures, accepted for publication in Europhysics Letter

The First Swift BAT Gamma-Ray Burst Catalog

We present the first Swift Burst Alert Telescope (BAT) catalog of gamma-ray bursts (GRBs), which contains bursts detected by the BAT between 2004 December 19 and 2007 June 16. This catalog (hereafter BAT1 catalog) contains burst trigger time, location, 90% error radius, duration, fluence, peak flux, and time averaged spectral parameters for each of 237 GRBs, as measured by the BAT. The BAT-determined position reported here is within 1.75' of the Swift X-ray Telescope (XRT)-determined position for 90% of these GRBs. The BAT T_90 and T_50 durations peak at 80 and 20 seconds, respectively. From the fluence-fluence correlation, we conclude that about 60% of the observed peak energies, Epeak, of BAT GRBs could be less than 100 keV. We confirm that GRB fluence to hardness and GRB peak flux to hardness are correlated for BAT bursts in analogous ways to previous missions' results. The correlation between the photon index in a simple power-law model and Epeak is also confirmed. We also report the current status for the on-orbit BAT calibrations based on observations of the Crab Nebula.Comment: 63 pages, 23 figures, Accepted in ApJS, Corrected for the BAT ground position, the image significance, and the error radius of GRB 051105, Five machine-readable tables are available at http://swift.gsfc.nasa.gov/docs/swift/results/bat1_catalog

Confirmation of the \eps -- \eiso (Amati) relation from the X-ray flash XRF 050416A observed by Swift/BAT

We report Swift Burst Alert Telescope (BAT) observations of the X-ray Flash (XRF) XRF 050416A. The fluence ratio between the 15-25 keV and 25-50 keV energy bands of this event is 1.5, thus making it the softest gamma-ray burst (GRB) observed by BAT so far. The spectrum is well fitted by the Band function with E^{\rm obs}_{\rm peak} of 15.0_{-2.7}^{+2.3} keV. Assuming the redshift of the host galaxy (z = 0.6535), the isotropic-equivalent radiated energy E_{\rm iso} and the peak energy at the GRB rest frame (E^{\rm src}_{\rm peak}) of XRF 050416A are not only consistent with the correlation found by Amati et al. and extended to XRFs by Sakamoto et al., but also fill-in the gap of this relation around the 30 - 80 keV range of E^{\rm src}_{\rm peak}. This result tightens the validity of the E^{\rm src}_{\rm peak} - E_{\rm iso} relation from XRFs to GRBs. We also find that the jet break time estimated using the empirical relation between E^{\rm src}_{\rm peak} and the collimation corrected energy E_{\gamma} is inconsistent with the afterglow observation by Swift X-ray Telescope. This could be due to the extra external shock emission overlaid around the jet break time or to the non existence of a jet break feature for XRF, which might be a further challenging for GRB jet emission, models and XRF/GRB unification scenarios.Comment: 16 pages, 4 figures; accepted for publication in ApJ

GRB 051221A and Tests of Lorentz Symmetry

Various approaches to quantum gravity suggest the possibility of violation of Lorentz symmetry at very high energies. In these cases we expect a modification at low energies of the dispersion relation of photons that contains extra powers of the momentum suppressed by a high energy scale. These terms break boost invariance and can be tested even at relatively low energies. We use the light curves of the very bright short Gamma-Ray Burst GRB 051221A and compare the arrival times of photons at different energies with the expected time delay due to a modified dispersion relation. As no time delay was observed, we set a lower bound of 0.0066 E_{pl} \sim 0.66 10^{17} GeV on the scale of Lorentz invariance violation.Comment: 9 pages, 2 figure

Discovery of Dipolar Chromospheres in Two White Dwarfs

This paper reports the ULTRACAM discovery of dipolar surface spots in two cool magnetic white dwarfs with Balmer emission lines, while a third system exhibits a single spot, similar to the prototype GD 356. The light curves are modeled with simple, circular, isothermal dark spots, yielding relatively large regions with minimum angular radii of 20 deg. For those stars with two light curve minima, the dual spots are likely observed at high inclination (or colatitude), however, identical and antipodal spots cannot simultaneously reproduce both the distinct minima depths and the phases of the light curve maxima. The amplitudes of the multi-band photometric variability reported here are all several times larger than that observed in the prototype GD 356; nevertheless, all DAHe stars with available data appear to have light curve amplitudes that increase toward the blue in correlated ratios. This behavior is consistent with cool spots that produce higher contrasts at shorter wavelengths, with remarkably similar spectral properties given the diversity of magnetic field strengths and rotation rates. These findings support the interpretation that some magnetic white dwarfs generate intrinsic chromospheres as they cool, and that no external source is responsible for the observed temperature inversion. Spectroscopic time-series data for DAHe stars is paramount for further characterization, where it is important to obtain well-sampled data, and consider wavelength shifts, equivalent widths, and spectropolarimetry.Comment: 9 pages, 5 figures, 3 tables, accepted to MNRA