Modelling of deuterium chemistry and its application to molecular clouds

We have developed new models of the chemistry of deuterium for investigating fractionation in interstellar molecular clouds. We have incorporated the latest information on reactions which affect deuteration, extended previous models to include S-D bonds for the first time and included the gasphase chemistry of some doubly-deuterated species. We present models for a wide range of physical parameters, including density, temperature, elemental abundances, and the freeze out of molecules on to dust grains. We discuss the detailed fractionation of particular species and show how fractionation can be used to probe the history of interstellar matter. The freeze out of molecules onto dust leads to significant enhancement in fractionation ratios and, in particular, to large fractionation in doubly-deuterated species.

A three-position spectral line survey of sagittarius B2 between 218 and 263 GHz. II. Data analysis

We present an analysis of the data from our Swedish-ESO Submillimetre Telescope molecular line survey in the 1.3 mm band of the N, M, and NW positions in the Sgr B2 molecular cloud. The line emissions from 42 molecular species, and some of their isotopomers, were analyzed assuming a single temperature and a homogeneous source. In cases where a source size much smaller than the antenna beam (23

ISO-SWS observations of CO2 and H2O in R cassiopeiae

We present ISO-SWS spectra of the O-rich Mira variable R Gas, showing CO2 in absorption and emission, and H2O in absorption. The CO2 absorption feature is the 01(1)0 - 00(0)0 ro-vibrationaI band at 14.97 mu m. The emission features are the 10(0)0-01(1)0 and 11(1)0 - 02(2)0 re-vibrational transitions at 13.87 and 13.48 mu m respectively. The water absorption spectrum shows the nu(1) and nu(3) re-vibrational bands in the 2.75 - 3 mu m region. Using LTE models, we derive physical parameters for the features. We find the CO2 emission temperature to be similar to 1100 K. We discuss the nature of the CO2 feature at 15 mu m and show that it can be modeled as an emission/absorption band by deviating front thermal equilibrium for the population of the 01(1)0 vibrational level. The H2O absorption spectrum is shown to arise from gas at different temperatures, but can be fit reasonably well with two components at T = 950 K and T = 250 K. The CO2 emission and hut H2O absorption temperatures an similar, suggesting chat these features probe the same region of the inner envelope. We discuss the inner envelope chemistry using molecular equilibrium calculations and recent modeling work by Duari et al. (1999), and find our observations consistent with the results.

Turbulent diffusion and mixing in interstellar dark clouds with adsorption onto grains

This paper reports the results of models of dark cloud chemistry incorporating a depth dependent density distribution with diffusive mixing and adsorption onto grains. The model is based on the approach taken by Xie et al. (1995), with the addition of grain accretion effects. Without diffusion, the central regions of the cloud freeze out in less than 10(7) years. Freeze-out time is dependent on density, so the diffuse outer region of the cloud remains abundant in gas for about an order of magnitude longer. We find that fairly small amounts of diffusive mixing can delay freeze-out at the centre of the model cloud for a time up to an order of magnitude greater than without diffusion, due to material diffusing inward from the edges of the cloud. The gas-phase lifetime of the cloud core can thus be increased by up to an order of magnitude or more by this process. We have run three different grain models with various diffusion coefficients to investigate the effects of changing the sticking parameters.

Automated detection and tracking of solar magnetic bright points

Magnetic bright points (MBPs) in the internetwork are among the smallest objects in the solar photosphere and appear bright against the ambient environment. An algorithm is presented that can be used for the automated detection of the MBPs in the spatial and temporal domains. The algorithm works by mapping the lanes through intensity thresholding. A compass search, combined with a study of the intensity gradient across the detected objects, allows the disentanglement of MBPs from bright pixels within the granules. Object growing is implemented to account for any pixels that might have been removed when mapping the lanes. The images are stabilized by locating long-lived objects that may have been missed due to variable light levels and seeing quality. Tests of the algorithm, employing data taken with the Swedish Solar Telescope, reveal that approximate to 90 per cent of MBPs within a 75 x 75 arcsec(2) field of view are detected.

Energy levels, radiative rates, and electron impact excitation rates for transitions in OVII

Aims.
In this paper we report calculations for energy levels, radiative rates, and electron impact excitation rates for transitions in O vii.
Methods.
The grasp (general-purpose relativistic atomic structure package) is adopted for calculating energy levels and radiative
rates. For determining the collision strengths and subsequently the excitation rates, the Dirac atomic R-matrix code (darc) and the
flexible atomic code (fac) are used.
Results.
Oscillator strengths, radiative rates, and line strengths are reported for all E1, E2, M1, and M2 transitions among the lowest
49 levels of O vii. Collision strengths have been averaged over a Maxwellian velocity distribution, and the resulting effective collision
strengths are reported over a wide temperature range below 2 × 106 K. Additionally, lifetimes are also listed for all levels.
Key words.

Radiative rates and electron impact excitation rates for H-like Fe XXVI

Aims. In this paper we report on calculations for energy levels, radiative rates, collision strengths, and effective collision strengths for transitions among the lowest 25 levels of the n $\le$ 5 configurations of H-like Fe XXVI.
Methods. The general-purpose relativistic atomic structure package (GRASP) and Dirac atomic R-matrix code (DARC) are adopted for the calculations.
Results. Radiative rates, oscillator strengths, and line strengths are reported for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among the 25 levels. Furthermore, collision strengths and effective collision strengths are reported for all the 300 transitions among the above 25 levels over a wide energy (temperature) range up to 1500 Ryd (107.7 K). Comparisons are made with earlier available results and the accuracy of the data is assessed.

Energy levels and radiative rates for transitions in Ni XIX

Aims. In this paper we report calculations for energy levels and radiative rates for transitions in Ni XIX.

Energy levels and radiative rates for transitions in FeIX

Aims. In this paper we report calculations for energy levels and radiative rates for transitions in Fe IX.

Reterritorialising Canada: Arctic ice’s liquid modernity and the imagining of a Canadian archipelago

Studying mobile actor networks of moving people, objects, images, and discourses, in conjunction with changing time-spaces, offers a unique opportunity to understand important, and yet relatively neglected, “relational material” dynamics of mobility. A key example of this phenomenon is the recontinentalization of Canada amidst dramatically changing articulations of the meanings and boundaries of the Canadian land-ice- ocean mass. A notable reason why Canada is being re-articulated in current times is the extensiveness of Arctic thawing. The reconfiguration of space and “motility” options in the Arctic constitutes an example of how “materiality and sociality produce themselves together.” In this paper we examine the possibilities and risks connected to this recontinentalization of Canada’s North. In exploring the past, present, and immediate future of this setting, we advance the paradigmatic view that Canada’s changing Arctic is the key element in a process of transformation of Canada into a peninsular body encompassed within a larger archipelagic entity: a place more intimately attuned to its immense (and growing) coastal and insular routes.

Roles for the subiculum in spatial information processing, memory, motivation and the temporal control of behaviour

The subiculum is in a pivotal position governing the output of the hippocampal formation. Despite this, it is a rather under-explored and sometimes ignored structure. Here, we discuss recent data indicating that the subiculum participates in a wide range of neurocognitive functions and processes. Some of the functions of subiculum are relatively well-known-these include providing a relatively coarse representation of space and participating in, and supporting certain aspects of, memory (particularly in the dynamic bridging of temporal intervals). The subiculum also participates in a wide variety of other neurocognitive functions too. however. Much less well-known are roles for the subiculum, and particularly the ventral subiculum, in the response to fear, stress and anxiety, and in the generation of motivated behaviour (particularly the behaviour that underlies drug addiction and the response to reward). There is an emerging suggestion that the subiculum participates in the temporal control of behaviour. It is notable that these latter findings have emerged from a consideration of instrumental behaviour using operant techniques; it may well be the case that the use of the watermaze or similar spatial tasks to assess subicular function (on the presumption that its functions are very similar to the hippocampus proper) has obscured rather than revealed neurocognitive functions of subiculum. The anatomy of subiculum suggests it participates in a rather subtle fashion in a very broad range of functions, rather than in a relatively more isolated fashion in a narrower range of functions, as might be the case for

Reconfiguring spaces of conflict: Northern Ireland and the impact of European integration

The Irish border has historically been one of the most contested borders in Europe. In the context of the peace process and EU membership, co-operation between Northern Ireland and the Republic of Ireland has been encouraged, supported and normalised, although internal borders of segregation stubbornly remain. This paper offers a conceptualisation of borders in conflict cases and a theoretical account of how European integration can affect their transformation. Analysis of the Northern Ireland case shows there are ambiguities within integration that allow for a ‘rebordering’ of identities at the same time as the state border diminishes in significance.

The masses and radii of HD 186753B and TYC7096-222-1B: the discovery of two M-dwarfs that eclipse A-type stars

We present observations of two new single-lined eclipsing binaries, both consisting of an Am star and an M-dwarf, discovered by the Wide Angle Search for Planets transit photometry survey. Using WASP photometry and spectroscopic measurements we find that HD 186753B has an orbital period of P=1.9194 days, a mass of M=0.24±0.02~M? and radius of R=0.31+0.06-0.06~R?; and that TCY7096-222-1B has an orbital period of P=8.9582 days, a mass of between 0.29 and 0.54 M? depending on eccentricity and radius of R=0.263+0.02-0.07~R?. We find that the Am stars have relatively low rotational velocities that closely match the orbital velocities of the M-dwarfs, suggesting that they have been “spun-down” by the M-dwarfs.

Thisness and Events

This essay is an investigation into the existence of primitive thisness, i.e. the property of being a particular individual. I begin with a look at what is commonly taken to be the test for primitive thisness, namely, the failure of application of the principle of the Identity of Indiscernibles for some class of individuals. The two classes that I look at are those of material objects and events. I then discuss Hacking’s objection to the general project of seeking counterexamples to the Identity of Indiscernibles, and consider a response due to Adams. I argue that Hacking’s objection does, indeed, count against the instantiation of thisness by material objects. I go on to argue, however, that Hacking’s objection does not hold against the instantiation of thisness by events, and that this is due to a fundamental disanalogy between space and time.