8,123 research outputs found
City and Countryside Revisited. Comparative rent movements in London and the South-East, 1580-1914
Economic historians have traditionally argued that urban growth in England was driven primarily by prior improvements in agricultural supply in the two centuries before the industrial revolution. Recent revisionist scholarship by writers such as Jan Luiten van Zanden and Robert Allen has suggested that 'the city drove the countryside, not the reverse'. This paper assembles new serial data on urban and agricultural rent movements in Kent, Essex and London, from 1580-1914, which enables us to provide a tentative estimate of the strength of the urban variable and the productivity of land across the rural-urban continuum. Our initial findings support the revisionist view, and throw new light on London's position within the wider metropolitan region. Comparative rent movements suggests a greater continuity between town and countryside than has often been assumed, with sharp increases in rental values occurring on the rural-urban fringes of London and the lower Medway valley
Review of \u3ci\u3eThe Ecology and Management of Prairies in the Central United States.\u3c/i\u3e By Chris Helzer.
This relatively short book is an informative and easyto- read account of the author\u27s philosophy and advice on how to manage prairies in the Central U.S., an area corresponding to the eastern portion of the Great Plains where tall- and mixed-grass prairie occurred. With fragmentation and huge losses of this region\u27s natural prairie habitat, there is a growing appreciation for active management of remnants and prairie restoration. This book provides an excellent introduction to this topic
Review of \u3ci\u3eThe Ecology and Management of Prairies in the Central United States.\u3c/i\u3e By Chris Helzer.
This relatively short book is an informative and easyto- read account of the author\u27s philosophy and advice on how to manage prairies in the Central U.S., an area corresponding to the eastern portion of the Great Plains where tall- and mixed-grass prairie occurred. With fragmentation and huge losses of this region\u27s natural prairie habitat, there is a growing appreciation for active management of remnants and prairie restoration. This book provides an excellent introduction to this topic
The transition from a coherent optical vortex to a Rankine vortex: beam contrast dependence on topological charge
Spatially coherent helically phased light beams carry orbital angular momentum (OAM) and contain phase singularities at their centre. Destructive interference at the position of the phase singularity means the intensity at this point is necessarily zero, which results in a high contrast between the centre and the surrounding annular intensity distribution. Beams of reduced spatial coherence yet still carrying OAM have previously been referred to as Rankine vortices. Such beams no longer possess zero intensity at their centre, exhibiting a contrast that decreases as their spatial coherence is reduced. In this work, we study the contrast of a vortex beam as a function of its spatial coherence and topological charge. We show that beams carrying higher values of topological charge display a radial intensity contrast that is more resilient to a reduction in spatial coherence of the source
Shawnee National Forest Vegetation Plot Analysis
Prescribed burns were conducted in 2675 acres (12 individual burn units) in the Hidden Springs and Vienna Ranger District of the Shawnee National Forest in southern Illinois. The prescribed burning program was conducted with the goal of improving wildlife habitat and timber stand condition. Stand condition was monitored from 2004 through 2009 (2013 in two sites) to assess the success in reducing the abundance of undesirable shade tolerant mesic species and increase regeneration of desirable shade intolerant taxa. The results of analyzing data from the monitoring program are reported here from 13 of 23 permanent monitoring plots. Over the first five years of this program the stands are generally increasing in basal area and decreasing in tree density as expected through normal stand maturation. There are indications that the prescribed burning program has been successful in some sites through a reduction in maples and an increase in oaks and hickories, an increase in the herb and shrub layer species richness, and a decrease in the exotic Japanese honeysuckle. The success of prescribed burning as a management tool is site-specific, varying across the landscape, and likely reflecting historical contingency. Continued monitoring of these sites is necessary; analysis of data from additional permanent plots is recommended as is improved intensity of the prescribed burns to enhance efficacy of the management treatment
What do loose groups tell us about galaxy formation?
We present the results of a Parkes Multibeam HI survey of six loose groups of
galaxies analogous to the Local Group. This survey was sensitive to HI-rich
objects in these groups to below 10^7 M(sun) of HI, and was designed to search
for low mass, gas-rich satellite galaxies and potential analogs to the
high-velocity clouds seen around the Milky Way. This survey detected a total of
79 HI-rich objects associated with the six groups, half of which were new
detections. While the survey identified a small number of dwarf galaxies, no
star-free HI clouds were discovered. The HI mass function of the six groups
appears to be roughly flat as is that of the Local Group. The cumulative
velocity distribution function (CVDF) of the HI-rich halos in the six groups is
identical to that of the Local Group. Both of these facts imply that these
groups are true analogs to the Local Group and that the Local Group is not
unique in its lack of low-mass dwarf galaxies as compared to the predictions of
cold dark matter models of galaxy formation. This survey also constrains the
distance to and HI masses of the compact high-velocity clouds (CHVCs) around
the Milky Way. The lack of CHVC analog detections implies that they are
distributed within <160 kpc of the Milky Way and have average HI masses of
<4x10^5 M(sun). The spatial distribution of CHVCs is consistent with the
predictions of simulations for dark matter halos. Furthermore the CVDF of Local
Group galaxies plus CHVCs matches the predicted CVDF of cold dark matter
simulations of galaxy formation. This provides circumstantial evidence that
CHVCs may be associated with low-mass dark matter halos.Comment: 4 pages, to appear in the proceedings of "Baryons in Dark Matter
Halos" Eds R-J., Dettmar, U. Klein, P. Salucci, PoS, SISSA,
http://pos.sissa.i
Population Dynamics of Endangered Iresine Rhizomatosa (Juda’s Bush)
Population changes of Iresine rhizomatosa Standl. (Juda’s bush, bloodleaf: Amaranthaceae) a State listed (Endangered in Illinois and Maryland, Rare in Indiana) perennial bush of floodplain forests is reported. The size/stage class distribution of I. rhizomatosa plants in Beall Woods and Robeson Hills, Illinois was determined to assess the proportional representation of individuals of different sizes, and monitor fecundity. One hundred randomly located individuals were tagged in each population in March 2012 and monitored for two years. Seedling emergence was monitored from fall 2012 through spring 2013. The number of flowering spikes, and numbers of seed produced were monitored on randomly selected adult plants in fall 2012. Survivorship of seedlings was low (\u3c 50%), re-growth of plants was poor, and seeds had low viability (8-12%) and germination rate (\u3c 1%); all features consistent with the rare status of this state-endangered plant. As a perennial, this plant is buffered to some extent against periods of poor recruitment, but populations would be at risk if these coincided with periods of high adult mortality
An HI census of Loose Groups of Galaxies
We present results from our Parkes Multibeam HI survey of 3 loose groups of
galaxies that are analogous to the Local Group. This is a survey of groups
containing only spiral galaxies with mean separations of a few hundred kpc, and
total areas of approximately 1 sq. Mpc; groups similar to our own Local Group.
We present a census of the HI-rich objects in these groups down to an M(HI),
1-sigma sensitivity ~7x10^5 M(sun), as well as the detailed properties of these
detections from follow-up Compact Array observations. We found 7 new HI-rich
members in the 3 groups, all of which have stellar counterparts and are,
therefore, typical dwarf galaxies. The ratio of low-mass to high-mass gas-rich
galaxies in these groups is less than in the Local Group meaning that the
``missing satellite'' problem is not unique. No high-velocity cloud analogs
were found in any of the groups. If HVCs in these groups are the same as in the
Local Group, this implies that HVCs must be located within ~300-400 kpc of the
Milky Way.Comment: 6 pages, to appear in the ASP proceedings of IAU Symposium 217,
"Recycling intergalactic and interstellar matter", eds. Pierre-Alain Duc,
Jonathan Braine, Elias Brink
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