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1.
Los Angeles is often described as the epitome of urban fragmentation, a notion which in this context is frequently connected to, or even conflated with urban sprawl. At the same time, the city features integrated water and power networks which have been under public ownership for over 70 years. We thus have an apparent paradox in the context of the debate on ‘splintering urbanism’, between socio-spatial fragmentation and the integration of networks. In discussing the idea that deregulation of infrastructural networks exacerbates urban fragmentation, the authors use the case of Los Angeles in order to highlight the central role of private interests in management decisions concerning infrastructure networks. The authors carry out their analysis in an historical perspective, revealing that network integration and universal access can often serve private interests more than the public good. Urban fragmentation in Los Angeles, they conclude, is the result of a complex process of instrumentalisation of network development and management. 相似文献
2.
A new parameterization for atmospheric transmission and O2 photodissociation in the Schumann-Runge band region has been developed and tested with a 1D radiative-photochemical model. The parameterization is based on the O2-column along the line of sight to the Sun and the local temperature. Line-by-line calculations have served as a benchmark for testing this method and several other, commonly used, parameterizations. The comparisons suggest that differences between the line-by-line calculations and currently accepted parameterizations can be reduced significantly by using the new method, particularly at large solar zenith angles. The production rate of O-atoms computed with this method shows less than 6% deviation compared to the line-by-line calculations at any altitude, all solar zenith angles and in all seasons. The largest errors are found toward the shorter wavelengths in the Schumann-Runge region at low altitudes. Transmittance is approximated to better than 4% at any altitude and/or solar zenith angle. The total O-production rate above 20 km is approximated to better than 2%. The new parameterization is easily implemented in existing photochemical models and in many cases it may simply replace the existing algorithm. The computational effort exceeds that of other parameterizations but in view of the total computation time needed for the actual calculation of the parameterized Schumann-Runge bands this should not lead to significant performance degeneration. The first 14 coefficients of the parameterization are included in this study. Both the complete sets of coefficients and a simple algorithm can be obtained by contacting the authors. A photochemical model study shows the largest effect of the parameterization method is on odd hydrogen concentrations. Subsequent interaction with an odd oxygen family causes differences in the ozone concentrations between the different parameterizations of more than 10% at selected altitudes. Although it is already established that deficiencies in the treatment of Schumann-Runge band absorption are unlikely to explain the current underestimation of ozone concentration at the stratopause in a variety of photochemical models, this study does show that the choice of parameterization has a large impact on the accuracy of the results at large solar zenith angles and in different seasons. 相似文献
3.
I.C. McDade E.J. Llewellyn R.G.H. Greer D.P. Murtagh 《Planetary and Space Science》1982,30(11):1133-1136
A simple vibrational relaxation model which reproduces the observed altitude integrated vibrational distribution of the Herzberg I bands in the nightglow is used to derive the altitude profiles of the individual vibrational levels at 1 km intervals in the 85–115 km height range. The possible errors associated with using rocket-borne photometer measurements of a limited number of bands in the O2(A3Σu+?X3Σg?) system to infer the total Herzberg I emission profile are assessed. 相似文献
4.
M. J. López-González D. P. Murtagh P. J. Espy J. J. López-Moreno R. Rodrigo G. Witt 《Annales Geophysicae》1996,14(1):59-67
The temporal variation of OH* emission and weighted rotational temperature has been studied for high-latitude summer conditions. Observations for 60°N latitude show OH weighted temperatures that always exceed 145 K even during periods of noctilucent clouds. Using a one-dimensional model the effects in excited OH concentration produced by changes in temperature, eddy diffusion, and water concentration have been analysed. We are forced to conclude that there remains a discrepancy between the OH temperatures predicted by the model and that obtained from OH* measurements. An increase in OH* concentration from June to the beginning of August, followed by a slow decrease during August has been obtained in agreement with the measurements. The 16-day modulation present in the measurements was simulated in a simple manner by varying the temperature in the mesopause region. This variation produces periodic modulations in both OH* concentration and weighted temperature of 16 days. The results show the temperature leading the OH* column concentration by three days. This phase shift is also present in the observations. 相似文献
5.
Earth observation relies heavily on imaging. Extraction of informationin turn relies on image processing and analysis. A new and powerfulmethodology has come to the fore in recent years, based on the waveletand other multiscale transforms. Of the many possible application areaswe describe in this paper some approaches for object and feature findingin images', noise filtering of synthetic aperture radar (SAR) images, andthe automatic geometrical registration of different images. 相似文献
6.
M. S. Johnston P. Eriksson S. Eliasson C. G. Jones R. M. Forbes D. P. Murtagh 《Climate Dynamics》2012,39(11):2713-2731
Tropical upper tropospheric humidity, clouds, and ice water content, as well as outgoing longwave radiation (OLR), are evaluated in the climate model EC Earth with the aid of satellite retrievals. The Atmospheric Infrared Sounder and Microwave Limb Sounder together provide good coverage of relative humidity. EC Earth’s relative humidity is in fair agreement with these observations. CloudSat and CALIPSO data are combined to provide cloud fractions estimates throughout the altitude region considered (500–100?hPa). EC Earth is found to overestimate the degree of cloud cover above 200?hPa and underestimate it below. Precipitating and non-precipitating EC Earth ice definitions are combined to form a complete ice water content. EC Earth’s ice water content is below the uncertainty range of CloudSat above 250?hPa, but can be twice as high as CloudSat’s estimate in the melting layer. CERES data show that the model underestimates the impact of clouds on OLR, on average with about 9?W?m?2. Regionally, EC Earth’s outgoing longwave radiation can be ～20?W?m?2 higher than the observation. A comparison to ERA-Interim provides further perspectives on the model’s performance. Limitations of the satellite observations are emphasised and their uncertainties are, throughout, considered in the analysis. Evaluating multiple model variables in parallel is a more ambitious approach than is customary. 相似文献
7.
Murtagh A 《Irish geography : bulletin of the Geographical Society of Ireland》2010,43(2):149-159
Getting food to our plates has become a highly complex, industrialised and globalised process. However, transformations in how our food is supplied are not without resistance. Initiatives are emerging that take a step back to simpler, alternative methods of food supply, bringing the producer and consumer closer together. Alternative food initiatives which are commonly found in Ireland include allotments, community gardens, farmers' markets, farm shops and on-farm food enterprises. Understanding alternative food activities as a social movement can illuminate a fresh perspective on their nature and potential. While briefly considering the broad dynamics of alternative food activity in Ireland, this exploratory paper looks at the question of the nature of resistance and whether a collective vision may exist across initiatives, illustrated by two examples, a community garden and consumer food co-op. Finally some conclusions as to how alternative food initiatives may play a transformative role within the contemporary food system are discussed. 相似文献
8.
Eight thousand images of the solar corona were captured during the June 2001 total solar eclipse. New software for the alignment
of the images and an automated technique for detecting intensity oscillations using multi-scale wavelet analysis were developed.
Large areas of the images covered by the Moon and the upper corona were scanned for oscillations and the statistical properties
of the atmospheric effects were determined. The à Trous wavelet transform was used for noise reduction and Monte Carlo analysis as a significance test of the detections. The effectiveness
of those techniques is discussed in detail. 相似文献
9.
James Glynn Maurizio Gargiulo Alessandro Chiodi Paul Deane Fionn Rogan Brian Ó Gallachóir 《Climate Policy》2019,19(1):30-42
The Paris Agreement is the last hope to keep global temperature rise below 2°C. The consensus agrees to holding the increase in global average temperature to well below 2°C above pre-industrial levels, and to aim for 1.5°C. Each Party’s successive nationally determined contribution (NDC) will represent a progression beyond the party’s then current NDC, and reflect its highest possible ambition. Using Ireland as a test case, we show that increased mitigation ambition is required to meet the Paris Agreement goals in contrast to current EU policy goals of an 80–95% reduction by 2050. For the 1.5°C consistent carbon budgets, the technically feasible scenarios' abatement costs rise to greater than €8,100/tCO2 by 2050. The greatest economic impact is in the short term. Annual GDP growth rates in the period to 2020 reduce from 4% to 2.2% in the 1.5°C scenario. While aiming for net zero emissions beyond 2050, investment decisions in the next 5–10 years are critical to prevent carbon lock-in.
Key policy insights
Economic growth can be maintained in Ireland while rapidly decarbonizing the energy system.
The social cost of carbon needs to be included as standard in valuation of infrastructure investment planning, both by government finance departments and private investors.
Technological feasibility is not the limiting factor in achieving rapid deep decarbonization.
Immediate increased decarbonization ambition over the next 3–5 years is critical to achieve the Paris Agreement goals, acknowledging the current 80–95% reduction target is not consistent with temperature goals of ‘well below’ 2°C and pursuing 1.5°C.
Applying carbon budgets to the energy system results in non-linear CO2 emissions reductions over time, which contrast with current EU policy targets, and the implied optimal climate policy and mitigation investment strategy.
10.
F.D. Murtagh 《Astrophysics and Space Science》1997,247(1-2):31-40
Astronomy as a discipline is essentially online and digital. It thus offers an ideal framework for the examination of current
trends in electronic publishing. Electronic publishing is driven on the winds of various underlying technologies. We look
at a number of these, focusing on information access and retrieval.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献