3,381 research outputs found
Is practice aligned with the principles? Implementing New Urbanism in Perth, Western Australia
New Urbanism is a recent American reform approach to urban development, which attempts to reduce car dependence through traditional design qualities such as connected streets with paths, higher density and mix with local centres. The Western Australian State Government has developed âLiveable Neighbourhoodsâ, which is a context-specific design code based on new Urbanist principles. This design code has been applied in the development of several dozen new neighbourhoods in Perth over the last decade. This paper shows that these developments do create more local walking but are no different to conventional suburban development in their regional car dependence. The causes of this are pursued in terms of a gap between principles and practice
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Forecasting camping tourism demand in Americaâs national parks using a machine learning approach
Camping has emerged as a growing sector of tourism. Within the context of the United States, where national parks are designated with the goal of preserving the natural ecosystem, this growing demand is met with a fixed supply of campsites. It is therefore important for agency managers to be able to understand and model future demand for their finite accommodations so that they might better allocate resources and disseminate projected demand trends to park visitors planning their national park journeys. This presentation describes the state of affairs concerning camping tourism within US national parks and presents an analysis using six forecasting methods to project future campsite demand. This includes a discussion of how the unique nature of camping tourism and the behavior of automobile campers present unexplored challenges for forecasting
Clustering Phase Transitions and Hysteresis: Pitfalls in Constructing Network Ensembles
Ensembles of networks are used as null models in many applications. However,
simple null models often show much less clustering than their real-world
counterparts. In this paper, we study a model where clustering is enhanced by
means of a fugacity term as in the Strauss (or "triangle") model, but where the
degree sequence is strictly preserved -- thus maintaining the quenched
heterogeneity of nodes found in the original degree sequence. Similar models
had been proposed previously in [R. Milo et al., Science 298, 824 (2002)]. We
find that our model exhibits phase transitions as the fugacity is changed. For
regular graphs (identical degrees for all nodes) with degree k > 2 we find a
single first order transition. For all non-regular networks that we studied
(including Erdos - Renyi and scale-free networks) we find multiple jumps
resembling first order transitions, together with strong hysteresis. The latter
transitions are driven by the sudden emergence of "cluster cores": groups of
highly interconnected nodes with higher than average degrees. To study these
cluster cores visually, we introduce q-clique adjacency plots. We find that
these cluster cores constitute distinct communities which emerge spontaneously
from the triangle generating process. Finally, we point out that cluster cores
produce pitfalls when using the present (and similar) models as null models for
strongly clustered networks, due to the very strong hysteresis which
effectively leads to broken ergodicity on realistic time scales.Comment: 13 pages, 11 figure
The Density Profiles of Massive, Relaxed Galaxy Clusters. II. Separating Luminous and Dark Matter in Cluster Cores
We present stellar and dark matter (DM) density profiles for a sample of
seven massive, relaxed galaxy clusters derived from strong and weak
gravitational lensing and resolved stellar kinematic observations within the
centrally-located brightest cluster galaxies (BCGs). In Paper I of the series,
we demonstrated that the total density profile derived from these data, which
span 3 decades in radius, is consistent with numerical DM-only simulations at
radii >~ 5-10 kpc, despite the significant contribution of stellar material in
the core. Here we decompose the inner mass profiles of these clusters into
stellar and dark components. Parametrizing the DM density profile as a power
law rho_DM ~ r^{-\beta} on small scales, we find a mean slope = 0.50 +-
0.10 (random) +0.14-0.13 (systematic). Alternatively, cored Navarro-Frenk-White
(NFW) profiles with = 1.14 +- 0.13 (random) +0.14-0.22
(systematic) provide an equally good description. These density profiles are
significantly shallower than canonical NFW models at radii <~ 30 kpc,
comparable to the effective radii of the BCGs. The inner DM profile is
correlated with the distribution of stars in the BCG, suggesting a connection
between the inner halo and the assembly of stars in the central galaxy. The
stellar mass-to-light ratio inferred from lensing and stellar dynamics is
consistent with that inferred using stellar population synthesis models if a
Salpeter initial mass function is adopted. We compare these results to theories
describing the interaction between baryons and DM in cluster cores, including
adiabatic contraction models and the possible effects of galaxy mergers and
active galactic nucleus feedback, and evaluate possible signatures of
alternative DM candidates.Comment: Updated to matched the published version in Ap
Changes in recreational behaviors of outdoor enthusiasts during the COVID-19 pandemic: analysis across urban and rural communities
The COVID-19 pandemic presents not only a global health crisis but has also disrupted the daily lives of people around the world. From a leisure perspective, urban outdoor enthusiasts are one group particularly impacted by the pandemic and the subsequent institutional response. Stay-at-home orders and physical distancing recommendations serve as potential inhibitors to outdoor recreation activities central to the lifestyles and wellbeing of outdoor enthusiasts. In urban areas, where these orders and recommendations are most restrictive, the potential impacts on recreation behavior are most consequential. This study provides an empirical analysis of the COVID-19 pandemicâs impact on the recreational behaviors of outdoor enthusiasts across urban and rural communities. Results suggest that the frequency of outdoor recreation participation, distance travelled to participate in outdoor recreation and distance travelled beyond roads during outdoor recreation have declined significantly more among outdoor enthusiasts residing in urban areas than urban clusters or rural areas
A revised Cepheid distance to NGC 4258 and a test of the distance scale
In a previous paper (Maoz et al. 1999), we reported a Hubble Space Telescope
(HST) Cepheid distance to the galaxy NGC 4258 obtained using the calibrations
and methods then standard for the Key Project on the Extragalactic Distance
Scale. Here, we reevaluate the Cepheid distance using the revised Key Project
procedures described in Freedman et al. (2001). These revisions alter the zero
points and slopes of the Cepheid Period-Luminosity (P-L) relations derived at
the Large Magellanic Cloud (LMC), the calibration of the HST WFPC2 camera, and
the treatment of metallicity differences. We also provide herein full
information on the Cepheids described in Maoz et al. 1999. Using the refined
Key Project techniques and calibrations, we determine the distance modulus of
NGC 4258 to be 29.47 +/- 0.09 mag (unique to this determination) +/- 0.15 mag
(systematic uncertainties in Key Project distances), corresponding to a metric
distance of 7.8 +/- 0.3 +/- 0.5 Mpc and 1.2 sigma from the maser distance of
7.2 +/- 0.5 Mpc. We also test the alternative Cepheid P-L relations of Feast
(1999), which yield more discrepant results. Additionally, we place weak limits
upon the distance to the LMC and upon the effect of metallicity in Cepheid
distance determinations.Comment: 26 pages in emulateapj5 format, including 6 figures and 5 tables.
Accepted for publication in the Astrophysical Journa
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Healthy Parks Healthy People: Evaluating and Improving Park Service Efforts to Promote Tourists Health and Well-being Introduction
Both Parks Victoria, AUS and the United States National Park Service (USNPS) focus on promoting human health and well-being while sustaining environmental well-being. This has been fostered by the agencies through the âHealthy Parks Healthy Peopleâ program, in which Parks Victoria and the USNPS are global leaders as well as agency collaborators. Given global concerns regarding health and well-being (human and environmental) this movement is crucial. However, in order for parks and associated tourism providers to implement effective health strategies, we must understand what a âhealthy parkâ is, how evidence is being promoted to existing and potential tourists, and what lessons can be learned from these agencies to facilitate these benefits globally in other settings. This research examines these questions across both agencies through content analyses, interviews, and assessments of tourism use trends. Results inform global park tourism planning and promotion efforts to improve social and ecological
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