Foreground removal from CMB temperature maps using an MLP neural network

One of the main obstacles for extracting the Cosmic Microwave Background (CMB) signal from observations in the mm-submm range is the foreground contamination by emission from Galactic components: mainly synchrotron, free-free and thermal dust emission. Due to the statistical nature of the intrinsic CMB signal it is essential to minimize the systematic errors in the CMB temperature determinations. Following the available knowledge of the spectral behavior of the Galactic foregrounds simple power law-like spectra have been assumed. The feasibility of using a simple neural network for extracting the CMB temperature signal from the combined signal CMB and the foregrounds has been investigated. As a specific example, we have analysed simulated data, as expected from the ESA Planck CMB mission. A simple multilayer perceptron neural network with 2 hidden layers can provide temperature estimates over more than 80 per cent of the sky that are to a high degree uncorrelated with the foreground signals. A single network will be able to cover the dynamic range of the Planck noise level over the entire sky.     

The dark matter environment of the Abell 901/902 supercluster: a weak lensing analysis of the HST STAGES survey

We present a high-resolution dark matter reconstruction of the   z = 0.165  Abell 901/902 supercluster from a weak lensing analysis of the Hubble Space Telescope STAGES survey. We detect the four main structures of the supercluster at high significance, resolving substructure within and between the clusters. We find that the distribution of dark matter is well traced by the cluster galaxies, with the brightest cluster galaxies marking out the strongest peaks in the dark matter distribution. We also find a significant extension of the dark matter distribution of Abell 901a in the direction of an infalling X-ray group Abell 901α. We present mass, mass-to-light and mass-to-stellar mass ratio measurements of the structures and substructures that we detect. We find no evidence for variation of the mass-to-light and mass-to-stellar mass ratio between the different clusters. We compare our space-based lensing analysis with an earlier ground-based lensing analysis of the supercluster to demonstrate the importance of space-based imaging for future weak lensing dark matter 'observations'.     

Could baseline establishment be counterproductive for emissions reduction? Insights from Vietnam’s building sector

This article provides insights into the role of institutions involved in climate governance working towards a future low-carbon society at the national level, within the global climate change governance architecture. Specifically, it contributes to understanding the fragmented governance of energy efficiency policy in developing countries by focussing on Vietnam’s building sector, identifying key institutions related to underlying discourses, national and international power relations, resource distribution and coalitions. It uses the case of baseline setting in developing Nationally Appropriate Mitigation Actions (NAMAs) to illustrate institutional dynamics, nationally and transnationally, as well as to question whether demands for baseline setting achieve the ideal trade-off between actual GHG emissions reduction and institutionalized demands for accountability. The analysis reveals that, in addition to domestic efforts and challenges, the international agenda greatly influences the energy efficiency policy arena. The article presents lessons to be learnt about policy processes from the specific Vietnamese case, reflecting on the role of international actors and discourses in it. Finally, it argues for the abolition of baselines in favour of adequate monitoring and evaluation, from the perspective that requirement for deviation from fictitious baselines is unproductive and only serves an international techno-managerial discourse.

POLICY RELEVANCE

Baseline establishment is commonly considered an initial step in developing NAMAs, in order to facilitate the demonstration of a deviation from such baselines. The requirement to produce baselines is traditionally not questioned by policy practitioners. Thus, significant development resources are allocated to the establishment of baselines and the bridging of data gaps, often without consideration as to whether baselines are a necessary instrument for NAMA implementation. We suggest omitting the lengthy and resource-consuming practice of establishing baselines and recommend proceeding forthwith to the planning and implementation of mitigation and energy efficiency policies. As conditions vary significantly in different contexts, it would be more appropriate to measure the initial situation, establishing the ‘base point’, and monitor development from that point. The present article might serve as motivation for policymakers to question traditional approaches to policy development and consider alternatives to maximize the cost efficacy of NAMA programmes and facilitate their implementation.     

For your eyes only? Evaluating a coordinated and multiple views tool with a map,a parallel coordinated plot and a table using an eye-tracking approach

Geographic visualization tools with coordinated and multiple views (CMV) typically provide sets of visualization methods. Such configuration gives users the possibility of investigating data in various visual contexts; however, it can be confusing due to the multiplicity of visual components and interactive functions. We addressed this challenge and conducted an empirical study on how a CMV tool, consisting of a map, a parallel coordinate plot (PCP), and a table, is used to acquire information. We combined a task-based approach with eye-tracking and usability metrics since these methods provide comprehensive insights into users’ behaviour. Our empirical study revealed that the freedom to choose visualization components is appreciated by users. The individuals worked with all the available visualization methods and they often used more than one visualization method when executing tasks. Different views were used in different ways by various individuals, but in a similarly effective way. Even PCP, which is claimed to be problematic, was found to be a handy way of exploring data when accompanied by interactive functions.     

Public perceptions of biodiversity in Norway: From recognition to stewardship?

The authors surveyed a representative sample of the Norwegian population (N = 4077) to examine perceptions of biodiversity loss and management, the relative importance of biodiversity loss to other environmental issues, and perceived implications of biodiversity loss. The results showed that 50% of the sample population saw biodiversity as a reality and major environmental issue, and 75% recognized that biodiversity loss occurs. Biodiversity loss was perceived as a lesser global environmental problem than environmental toxins, climate change, air and water pollution, and loss of rainforest, despite the fact that these topics can be difficult to separate since biodiversity loss is a function of other environmental problems. Loss of biodiversity was seen to have negative impacts on people's relationship to the natural environment, to impact environmental resilience, to be at least partly human-induced, and to be an issue of importance and relevance to the general public, not merely to the scientific community. Self-reported levels of knowledge of environmental topics were associated with increasing concern about consequences of reductions in species diversity. The authors conclude that efforts to increase public support for biodiversity conservation can be strengthened by increased emphasis on aesthetic, emotional and cultural aspects of biodiversity.     

Closing down bars in the inner city centre: Informal urban planning,civil insecurity and subjectivity in Bolivia

The paper presents an ethnographic analysis of a group of secondary school students' protests against (illegal) bars in the city centre of El Alto, Bolivia. It shows how informal and formal practices are entangled through the state's dependence on the (illegal) actions of the citizenry in order to ensure civil security. The paper suggests that urban intervention is coproduced by state and nonstate actors at the margins of the state and that urban transformation entails subject formation, in this case that of political youth. Following Hansen and Verkaaik's (2009) argument that the city is essentially multilayered and unknowable, I argue that urban life, as well as state‐citizen relations, is indeterminate, and that it is due to this indeterminacy that the students succeeded in transforming a common association between Alteño youth, alcohol consumption and potential criminal conduct into an alternative notion of youth as responsible citizens of the New Bolivia. This conceptualization permits us to understand the urban sphere as a space not only of conflict but also of endurance and hope, and hence as a zone that allows for the imaginative production of the otherwise (Povinelli, 2011).     

Meltwater production in Antarctic blue-ice areas: sensitivity to changes in atmospheric forcing

In the near coastal regions of Dronning Maud Land, Antarctica, below-surface ice-melt in blue-ice areas has been observed. The low scattering coefficients of the large-grained blue-ice allow penetration of solar radiation, thus providing an energy source below the ice surface. The sub-surface meltwater is significant enough to show up on remote-sensing imagery in the form of ice-covered lakes. Adjacent snow-accumulation areas have much higher scattering coefficients and consequently limit solar radiation penetration in these regions. These snow and ice surfaces are generally below freezing, and little surface melting occurs. To assess the response of these melt features to changes in atmospheric forcings such as cloudiness, air temperature, and snow accumulation, a physically-based model of the coupled atmosphere, radiation, snow, and blue-ice system has been developed. The model consists of a heat transfer equation with a spectrally-dependent solar-radiation source term. The penetration of radiation into the snow and blue-ice depends on the surface albedo, and the snow and blue-ice grain size and density. Model simulations show that ice melt occurring in this area is sensitive to potential variations in atmospheric forcing. Under certain conditions more traditional surface melting occurs and, under other conditions, the existing melt processes can be shut down completely. In light of the sensitivity of this system to variations in atmospheric forcing, and the ability to view melt-related features using remote sensing, a tool exists to efficiently monitor variations in Antarctic coastal climate.     

Effects of salinity on NH4 + adsorption capacity, nitrification, and denitrification in Danish estuarine sediments

The regulatory effect of salinity on nitrogen dynamics in estuarine sediments was investigated in the Randers Fjord estuary, Denmark, using sediment slurries and intact sediment cores and applying ¹⁵N-isotope techniques. Sediment was sampled at three representative stations varying in salinity, and all experiments were run at 0‰, 10‰, 20‰, and 30‰. The sediment NH₄ ⁺ adsorption capacity decreased markedly at all stations when salinity was increased from 0‰ to 10‰; further increase showed little effect. In situ nitrification and denitrification also decreased with increasing salinities, with the most pronounced reduction of approximately 50% being observed when the salinity was raised from 0‰ to 10‰. The salinity-induced reduction in NH₄ ⁺ adsorption capacity and stimulation of NH₄ ⁺ efflux has previously been argued to cause a reduction in nitrification activity since the nitrifying bacteria become limited by NH₄ ⁺ availability at higher salinities. However, using a potential nitrification assay where NH₄ ⁺ was added in excess, it was demonstrated that potential nitrification activity also decreased with increasing salinity, indicating that the inhibitory salinity effect may also be a physiological effect on the microorganisms. This hypothesis was supported by the finding that denitrification based on NO₃ ⁻ from the overlying water (D_w), which is independent of the nitrification process, and hence NH₄ ⁺ availability, also decreased with increasing salinity. We conclude that changes in salinity have a significant effect on nitrogen dynamics in estuarine sediments, which must be considered when nitrogen transformations are measured and evaluated.