158 research outputs found
Testing the Effect of Hedge Height on Perceived Safety-A Landscape Design Intervention
Access to safe, green urban environments is important for quality of life in cities. The objective of this study is to explore the impact of a safety-enhancing landscape design measure on visitors' experiences in an urban park. Additionally, this paper combines the use of field and virtual reality (VR) experiments, contributing methodological insights into how to evaluate safety measures in green space management and research on perceived safety. In a field experiment (n = 266), we explored whether the height of a hedge along a pathway influenced perceived safety among users. The field study showed that cutting down the hedge improved the perceived prospect of the immediate surrounding areas for female users, which again made them feel safer in the park. We developed a VR experiment for an evening scenario in the same environment (n = 19) to supplement the field study and test the effect of the intervention further. The VR experiment also found a gender effect on perceived safety, with females reporting lower perceived safety, but no effect was shown for the height of the hedge. The results in this study show that environmental attributes such as perceived prospect and concealment should be considered in the design and management of urban green spaces. Additionally, this research demonstrates an approach to conducting field experiments to test the effects of actual design interventions and then further developing these experiments using VR technology. Further research on perceived safety in outdoor spaces is needed to make use of this combined method's potential
Measuring Magnetic Fields in Ultracool Stars and Brown Dwarfs
We present a new method for direct measurement of magnetic fields on
ultracool stars and brown dwarfs. It takes advantage of the Wing-Ford band of
FeH, which are seen throughout the M and L spectral types. These molecular
features are not as blended as other optical molecular bands, are reasonably
strong through most of the spectral range, and exhibit a response to magnetic
fields which is easier to detect than other magnetic diagnostics, including the
usual optical and near-infrared atomic spectral lines that have heretofore been
employed. The FeH bands show a systematic growth as the star gets cooler. We do
not find any contamination by CrH in the relevant spectral region. We are able
to model cool and rapidly-rotating spectra from warmer, slowly-rotating spectra
utilizing an interpolation scheme based on optical depth scaling. We show that
the FeH features can distinguish between negligible, moderate, and high
magnetic fluxes on low-mass dwarfs, with a current accuracy of about one
kilogauss. Two different approaches to extracting the information from the
spectra are developed and compared. Which one is superior depends on a number
of factors. We demostrate the validity of our new procedures by comparing the
spectra of three M stars whose magnetic fluxes are already known from atomic
line analysis. The low and high field stars are used to produce interpolated
moderate-strength spectra which closely resemble the moderate-field star. The
assumption of linear behavior for the magnetic effects appears to be
reasonable, but until the molecular constants are better understood the method
is subject to that assumption, and rather approximate. Nonetheless, it opens a
new regime of very low-mass objects to direct confirmation and testing of their
magnetic dynamos.Comment: 36 preprint pages, accepted for publication in Ap
Line Intensities and Molecular Opacities of the FeH Transition
We calculate new line lists and opacities for the
transition of FeH. The 0-0 band of this transition is responsible for the
Wing-Ford band seen in M-type stars, sunspots and brown dwarfs. The new
Einstein A values for each line are based on a high level ab initio calculation
of the electronic transition dipole moment. The necessary rotational line
strength factors (H\"onl-London factors) are derived for both the Hund's case
(a) and (b) coupling limits. A new set of spectroscopic constants were derived
from the existing FeH term values for v=0, 1 and 2 levels of the and
states. Using these constants extrapolated term values were generated for v=3
and 4 and for values up to 50.5. The line lists (including Einstein A
values) for the 25 vibrational bands with v4 were generated using a
merged list of experimental and extrapolated term values. The FeH line lists
were use to compute the molecular opacities for a range of temperatures and
pressures encountered in L and M dwarf atmospheres. Good agreement was found
between the computed and observed spectral energy distribution of the L5 dwarf
2MASS-1507.Comment: 52 pages, 3 figures, many tables, accepted for publication in the
Astrophysical Journal Supplement
3D simulations of M star atmosphere velocities and their influence on molecular FeH lines
We present an investigation of the velocity fields in early to late M-type
star hydrodynamic models, and we simulate their influence on FeH molecular line
shapes. The M star model parameters range between log g of 3.0 - 5.0 and Teff
of 2500 K and 4000 K. Our aim is to characterize the Teff- and log g
-dependence of the velocity fields and express them in terms of micro- and
macro-turbulent velocities in the one dimensional sense. We present also a
direct comparison between 3D hydrodynamical velocity fields and 1D turbulent
velocities. The velocity fields strongly affect the line shapes of FeH, and it
is our goal to give a rough estimate for the log g and Teff parameter range in
which 3D spectral synthesis is necessary and where 1D synthesis suffices. In
order to calculate M-star structure models we employ the 3D
radiative-hydrodynamics (RHD) code CO5BOLD. The spectral synthesis on these
models is performed with the line synthesis code LINFOR3D. We describe the 3D
velocity fields in terms of a Gaussian standard deviation and project them onto
the line of sight to include geometrical and limb-darkening effects. The micro-
and macro-turbulent velocities are determined with the "Curve of Growth" method
and convolution with a Gaussian velocity profile, respectively. To characterize
the log g and Teff dependence of FeH lines, the equivalent width, line width,
and line depth are regarded. The velocity fields in M-stars strongly depend on
log g and Teff. They become stronger with decreasing log g and increasing Teff.Comment: 14 pages, 17 figures, 3 tables, accepted by Astronomy & Astrophysic
Rules, Norms and Practices – A Comparative Study Exploring Disposal Practices and Facilities in Northern Europe
We identify and analyse practices and management regimes around burial and handling of ashes across eight case study towns within six Northern European countries. We analyse management of cemeteries and crematoria gardens, majority practices and provision for minority communities, including various burial types, cremated remains, the re-use of graves, and costs for interments. Comparative data is drawn from analysis of national and local regulations, interviews with stakeholders, and observations at cemeteries and crematoria gardens. The findings show significant variation in national and local regulations and practices for burial and cremation particularly around the re-use of graves, handling of ashes and costs for grave space and cremation. We identify the opportunities and constraints of these variations in terms of accessibility, diversity and equality; and argue for national directions to avoid unequal treatment within nations. Furthermore, we stress the importance of a liberal and inclusive management of European cemeteries and crematoria gardens
Submillimeter Emission from Water in the W3 Region
We have mapped the submillimeter emission from the 1(10)-1(01) transition of
ortho-water in the W3 star-forming region. A 5'x5' map of the W3 IRS4 and W3
IRS5 region reveals strong water lines at half the positions in the map. The
relative strength of the Odin lines compared to previous observations by SWAS
suggests that we are seeing water emission from an extended region. Across much
of the map the lines are double-peaked, with an absorption feature at -39 km/s;
however, some positions in the map show a single strong line at -43 km/s. We
interpret the double-peaked lines as arising from optically thick,
self-absorbed water emission near the W3 IRS5, while the narrower blue-shifted
lines originate in emission near W3 IRS4. In this model, the unusual appearance
of the spectral lines across the map results from a coincidental agreement in
velocity between the emission near W3 IRS4 and the blue peak of the more
complex lines near W3 IRS5. The strength of the water lines near W3 IRS4
suggests we may be seeing water emission enhanced in a photon-dominated region.Comment: Accepted to A&A Letters as part of the special Odin issue; 4 page
Envelope structure of deeply embedded young stellar objects in the Serpens Molecular Cloud
Aperture synthesis and single-dish (sub) millimeter molecular lines and
continuum observations reveal in great detail the envelope structure of deeply
embedded young stellar objects (SMM1, SMM2, SMM3, SMM4) in the densely
star-forming Serpens Molecular Cloud. Resolved millimeter continuum emission
constrains the density structure to a radial power law with index -2.0 +/- 0.5,
and envelope masses of 8.7, 3.0, and 5.3 M_sol for SMM1, SMM3, and SMM4. The
core SMM2 does not seem to have a central condensation and may not have formed
a star yet. The molecular line observations can be described by the same
envelope model, if an additional, small amount of warm (100 K) material is
included. This probably corresponds to the inner few hundred AU of the envelope
were the temperature is high. In the interferometer beam, the molecular lines
reveal the inner regions of the envelopes, as well as interaction of the
outflow with the surrounding envelope. Bright HCO+ and HCN emission outlines
the cavities, while SiO and SO trace the direct impact of the outflow on
ambient gas. Taken together, these observations provide a first comprehensive
view of the physical and chemical structure of the envelopes of deeply embedded
young stellar objects in a clustered environment on scales between 1000 and
10,000 AU.Comment: 46 pages, incl. 12 postscript figures, uses ApJ latex and psfig
macro
First detection of NH3 (1,0 - 0,0) from a low mass cloud core: On the low ammonia abundance of the rho Oph A core
Odin has successfully observed the molecular core rho Oph A in the 572.5 GHz
rotational ground state line of ammonia, NH3 (J,K = 1,0 - 0,0). The
interpretation of this result makes use of complementary molecular line data
obtained from the ground (C17O and CH3OH) as part of the Odin preparatory work.
Comparison of these observations with theoretical model calculations of line
excitation and transfer yields a quite ordinary abundance of methanol, X(CH3OH)
= 3e-9. Unless NH3 is not entirely segregated from C17O and CH3OH, ammonia is
found to be significantly underabundant with respect to typical dense core
values, viz. X(NH3) = 8e-10.Comment: 4 pages, 2 figures, 2 tables, to appear in Astron. Astrophys. Letter
Water and ammonia abundances in S140 with the Odin satellite
We have used the Odin satellite to obtain strip maps of the ground-state
rotational transitions of ortho-water and ortho-ammonia, as well as CO(5-4) and
13CO(5-4) across the PDR, and H218O in the central position. A physi-chemical
inhomogeneous PDR model was used to compute the temperature and abundance
distributions for water, ammonia and CO. A multi-zone escape probability method
then calculated the level populations and intensity distributions. These
results are compared to a homogeneous model computed with an enhanced version
of the RADEX code. H2O, NH3 and 13CO show emission from an extended PDR with a
narrow line width of ~3 kms. Like CO, the water line profile is dominated by
outflow emission, however, mainly in the red wing. The PDR model suggests that
the water emission mainly arises from the surfaces of optically thick, high
density clumps with n(H2)>10^6 cm^-3 and a clump water abundance, with respect
to H2, of 5x10^-8. The mean water abundance in the PDR is 5x10^-9, and between
~2x10^-8 -- 2x10^-7 in the outflow derived from a simple two-level
approximation. Ammonia is also observed in the extended clumpy PDR, likely from
the same high density and warm clumps as water. The average ammonia abundance
is about the same as for water: 4x10^-9 and 8x10^-9 given by the PDR model and
RADEX, respectively. The similarity of water and ammonia PDR emission is also
seen in the almost identical line profiles observed close to the bright rim.
Around the central position, ammonia also shows some outflow emission although
weaker than water in the red wing. Predictions of the H2O(110-101) and
(111-000) antenna temperatures across the PDR are estimated with our PDR model
for the forthcoming observations with the Herschel Space Observatory.Comment: 13 pages, 14 figures, 10 tables. Accepted for publication in
Astronomy & Astrophysics 14 November 200
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