Extra-planar gas in the spiral galaxy NGC 4559

We present 21-cm line observations of the spiral galaxy NGC 4559, made with the Westerbork Synthesis Radio Telescope. We have used them to study the HI distribution and kinematics, the relative amount and distribution of luminous and dark matter in this galaxy and, in particular, the presence of extra-planar gas. Our data do reveal the presence of such a component, in the form of a thick disk, with a mass of 5.9 x 10^8 Mo (one tenth of the total HI mass) and a mean rotation velocity 25-50 km/s lower than that of the thin disk. The extra-planar gas may be the result of galactic fountains but accretion from the IGM cannot be ruled out. With this study we confirm that lagging, thick HI layers are likely to be common in spiral galaxies.Comment: 17 pages, 10 figures. Accepted for publication in A&

Kinematics of diffuse ionized gas in the disk halo interface of NGC 891 from Fabry-P\'erot observations

The properties of the gas in halos of galaxies constrain global models of the interstellar medium. Kinematical information is of particular interest since it is a clue to the origin of the gas. Here we report observations of the kinematics of the thick layer of the diffuse ionized gas in NGC 891 in order to determine the rotation curve of the halo gas. We have obtained a Fabry-P\'erot data cube in Halpha to measure the kinematics of the halo gas with angular resolution much higher than obtained from HI 21 cm observations. The data cube was obtained with the TAURUS II spectrograph at the WHT on La Palma. The velocity information of the diffuse ionized gas extracted from the data cube is compared to model distributions to constrain the distribution of the gas and in particular the halo rotation curve. The best fit model has a central attenuation tau_H-alpha=6, a dust scale length of 8.1 kpc, an ionized gas scale length of 5.0 kpc. Above the plane the rotation curve lags with a vertical gradient of -18.8 km/s/kpc. We find that the scale length of the H-alpha must be between 2.5 and 6.5 kpc. Furthermore we find evidence that the rotation curve above the plane rises less steeply than in the plane. This is all in agreement with the velocities measured in the HI.Comment: A&A, in press. 13 pages, 19 figure

A kinematic study of the irregular dwarf galaxy NGC 2366 using HI and Halpha observations

Abridged. Context. The metal content of dwarf galaxies and the metal enrichment of the intergalactic medium both suggest that mass loss from galaxies is a significant factor for the chemical evolution history of galaxies, in particular of dwarf galaxies. However, no clear evidence of a blow-away in local dwarf galaxies has been found so far. Aims. We therefore performed a detailed kinematic analysis of the neutral and ionised gas in the nearby star-forming irregular dwarf galaxy NGC 2366 in order to make predictions about the fate of the gas and to get a more complete picture of this galaxy. Methods. A deep Halpha image and Fabry-Perot interferometric data of NGC 2366 were obtained. They were complemented by HI synthesis data from the THINGS survey. We searched for line-splitting both in Halpha and HI by performing a Gaussian decomposition. To get an idea whether the expansion velocities are high enough for a gas blow-away, we used the pseudo-isothermal halo model, which gives us realistic values for the escape velocities of NGC 2366. The good data quality also allowed us to discuss some peculiarities of the morphology and the dynamics in NGC 2366. Results. A large red-shifted outflow north west of the giant extragalactic HII region with an expansion velocity of up to 50 km/s is found in Halpha, but not in HI. Additionally, a blue-shifted component north of the giant extragalactic HII region was detected both in Halpha and HI with an expansion velocity of up to 30 km/s. A comparison with the escape velocities of NGC 2366 reveals that the gas does not have enough kinetic energy to leave the gravitational potential.Comment: 15 pages, 14 figures, accepted for publication by A&

Embodied cognitive ecosophy: the relationship of mind, body, meaning and ecology

The concept of embodied cognition has had a major impact in a number of disciplines. The extent of its consequences on general knowledge and epistemology are still being explored. Embodied cognition in human geography has its own traditions and discourses but these have become somewhat isolated in the discipline itself. This paper argues that findings in other disciplines are of value in reconceptualising embodied cognition in human geography and this is explored by reconsidering the concept of ecosophy. Criticisms of ecosophy as a theory are considered and recent work in embodied cognition is applied to consider how such criticisms might be addressed. An updated conceptualisation is proposed, the embodied cognitive ecosophy, and three characteristics arising from this criticism and synthesis are presented with a view to inform future discussions of ecosophy and emotional geography

Diagnostic Dilemma of Small Incidentally Discovered Adrenal Masses: Role for 131 I-6β-Iodomethyl-norcholesterol Scintigraphy

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42408/1/268-21-1-36_21n1p36.pd

An H-alpha survey aiming at the detection of extraplanar diffuse ionized gas in halos of edge-on spiral galaxies. I. How common are gaseous halos among non-starburst galaxies?

In a series of two papers we present results of a new H-alpha imaging survey, aiming at the detection of extraplanar diffuse ionized gas in halos of late-type spiral galaxies. We have investigated a sample of 74 nearby edge-on spirals, covering the northern and southern hemisphere. In 30 galaxies we detected extraplanar diffuse emission at mean distances of |z|~1-2 kpc. Individual filaments can be traced out to |z|<= 6 kpc in a few cases. We find a good correlation between the FIR flux ratio (S_60/S_100) and the SFR per unit area (L_FIR/D^2_25), based on the detections/non-detections. This is actually valid for starburst, normal and for quiescent galaxies. A minimal SFR per unit area for the lowest S_60/S_100 values, at which extended emission has been detected, was derived, which amounts to (dE/dt)_A25^thres = (3.2+-0.5)x10E+40 erg/s/kpc^2. There are galaxies where extraplanar emission was detected at smaller values of L_FIR/D^2_25, however, only in combination with a significantly enhanced dust temperature. The results corroborate the general view that the gaseous halos are a direct consequence of SF activity in the underlying galactic disk.Comment: LaTeX, 12 pages, 7 figures, accepted for publication in A&

Cosmological radiative transfer comparison project - II. The radiation-hydrodynamic tests

The development of radiation hydrodynamical methods that are able to follow gas dynamics and radiative transfer (RT) self-consistently is key to the solution of many problems in numerical astrophysics. Such fluid flows are highly complex, rarely allowing even for approximate analytical solutions against which numerical codes can be tested. An alternative validation procedure is to compare different methods against each other on common problems, in order to assess the robustness of the results and establish a range of validity for the methods. Previously, we presented such a comparison for a set of pure RT tests (i.e. for fixed, non-evolving density fields). This is the second paper of the Cosmological Radiative Transfer Comparison Project, in which we compare nine independent RT codes directly coupled to gas dynamics on three relatively simple astrophysical hydrodynamics problems: (i) the expansion of an H ii region in a uniform medium, (ii) an ionization front in a 1/r2 density profile with a flat core and (iii) the photoevaporation of a uniform dense clump. Results show a broad agreement between the different methods and no big failures, indicating that the participating codes have reached a certain level of maturity and reliability. However, many details still do differ, and virtually every code has showed some shortcomings and has disagreed, in one respect or another, with the majority of the results. This underscores the fact that no method is universal and all require careful testing of the particular features which are most relevant to the specific problem at han

Numerical Relativity: A review

Computer simulations are enabling researchers to investigate systems which are extremely difficult to handle analytically. In the particular case of General Relativity, numerical models have proved extremely valuable for investigations of strong field scenarios and been crucial to reveal unexpected phenomena. Considerable efforts are being spent to simulate astrophysically relevant simulations, understand different aspects of the theory and even provide insights in the search for a quantum theory of gravity. In the present article I review the present status of the field of Numerical Relativity, describe the techniques most commonly used and discuss open problems and (some) future prospects.Comment: 2 References added; 1 corrected. 67 pages. To appear in Classical and Quantum Gravity. (uses iopart.cls

An H-alpha survey aiming at the detection of extraplanar diffuse ionized gas in halos of edge-on spiral galaxies II. The H-alpha survey atlas and catalog

In this second paper on the investigation of extraplanar diffuse ionized gas in nearby edge-on spiral galaxies we present the actual results of the individual galaxies of our H-alpha imaging survey. A grand total of 74 galaxies have been studied, including the 9 galaxies of a recently studied sub-sample (Rossa & Dettmar 2000). 40.5% of all studied galaxies reveal extraplanar diffuse ionized gas, whereas in 59.5% of the survey galaxies no extraplanar diffuse ionized gas could be detected. The average distances of this extended emission above the galactic midplane range from 1-2 kpc, while individual filaments in a few galaxies reach distances of up to |z| ~ 6 kpc. In several cases a pervasive layer of ionized gas was detected, similar to the Reynolds layer in our Milky Way, while other galaxies reveal only extended emission locally. The morphology of the diffuse ionized gas is discussed for each galaxy and is compared with observations of other important ISM constituents in the context of the disk-halo connection, in those cases where published results were available. Furthermore, we present the distribution of extraplanar dust in these galaxies, based on an analysis of the unsharp-masked R-band images. The results are compared with the distribution of the diffuse ionized gas.Comment: LaTeX, 21 pages, 7 figures, accepted for publication in A&A, figs. 22-54 are only available in electronic form and figs. 2-11 + 17-20 are also available at http://www.astro.rub.de/jrossa/ha-surve

Scintigraphy of incidentally discovered bilateral adrenal masses

The purpose of this study was to determine the patterns of iodine-131 6β-iodomethylnorcholesterol (NP-59) imaging and the correlation with computed tomography (CT)-guided adrenal biopsy and follow-up in patients with bilateral adrenal masses. To this end we investigated a consecutive sample of 29 euadrenal patients with bilateral adrenal masses discovered on CT for reasons other than suspected adrenal disease. Adrenal scintigraphy was performed using 1 mCi of NP-59 injected intravenously, with gamma camera imaging 5–7 days later. In 13 of the 29 patients bilateral adrenal masses were the result of metastatic involvement from lung carcinoma (5), lymphoma (3), adrenocarcinoma of the colon (3), squamous cell carcinoma of the larynx (1), and anaplastic carcinoma of unknown primary (1). Among these cases the NP-59 scan demonstrated either bilaterally absent tracer accumulation (in eight, all with bilateral metastases proven by CT guided biopsy or progression on follow-up CT) or marked asymmetry of adrenocortical NP-59 uptake (in five). Biopsy of the adrenal demonstrating the least NP-59 uptake documented malignant involvement of that gland in five of five patients. In two patients an adenoma was found simultaneously in one adrenal with a contralateral malignant adrenal mass. In each of these cases, the adenoma demonstrated the greatest NP-59 uptake. In 16 patients diagnosis of adenoma was made on the basis of (a) CT guided adrenal biopsy of the gland with the greatest NP-59 uptake of the pair ( n =4), or (b) adrenalectomy ( n =2), or (c) absence of change in the size of the adrenal mass on follow-up CT scanning performed 6 months to 3 years later ( n =10). It is concluded that differential in vivo functional information provided by NP-59 scintigraphy complements that derived from anatomic imaging and can be used in patients with bilateral adrenal masses to select which gland would be the best choice for further diagnostic invasive evaluation (e.g., adrenal biopsy) or may suggest the presence of bilateral adrenal metastases in patients with incidentally discovered, bilateral adrenal masses.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46838/1/259_2004_Article_BF00941847.pd