2,712 research outputs found
Phantom Housing: The Rise and Fall of Public Housing in North America
This paper examines the rise and fall of public housing in North America in order to explore the principle of sustainability. By extension, it addresses the concept of sustainability as it relates to the city. Urbanity is simultaneously the most and least sustainable form of development. While extremely sustainable from the point of view of density (economies of scale, efficient use ofinfrastructure, etc.), it is highly vulnerable to social, political and economic forces. Such forces can easily trump the environmental sustainability of any building or community.The death and transfiguration of key portions of our public housing stock provides insights into this phenomenon – for which I will use Toronto's Regent Park as a case study. The redevelopment ofthis 69-acre parcel aims to transform a failed social vision into a model for sustainable community development
Cosmic Dawn and Epoch of Reionization Foreground Removal with the SKA
The exceptional sensitivity of the SKA will allow observations of the Cosmic
Dawn and Epoch of Reionization (CD/EoR) in unprecedented detail, both
spectrally and spatially. This wealth of information is buried under Galactic
and extragalactic foregrounds, which must be removed accurately and precisely
in order to reveal the cosmological signal. This problem has been addressed
already for the previous generation of radio telescopes, but the application to
SKA is different in many aspects.
In this chapter we summarise the contributions to the field of foreground
removal in the context of high redshift and high sensitivity 21-cm
measurements. We use a state-of-the-art simulation of the SKA Phase 1
observations complete with cosmological signal, foregrounds and
frequency-dependent instrumental effects to test both parametric and
non-parametric foreground removal methods. We compare the recovered
cosmological signal using several different statistics and explore one of the
most exciting possibilities with the SKA --- imaging of the ionized bubbles.
We find that with current methods it is possible to remove the foregrounds
with great accuracy and to get impressive power spectra and images of the
cosmological signal. The frequency-dependent PSF of the instrument complicates
this recovery, so we resort to splitting the observation bandwidth into smaller
segments, each of a common resolution.
If the foregrounds are allowed a random variation from the smooth power law
along the line of sight, methods exploiting the smoothness of foregrounds or a
parametrization of their behaviour are challenged much more than non-parametric
ones. However, we show that correction techniques can be implemented to restore
the performances of parametric approaches, as long as the first-order
approximation of a power law stands.Comment: Accepted for publication in the SKA Science Book 'Advancing
Astrophysics with the Square Kilometre Array', to appear in 201
Local Perceptions of Water-Energy-Food Security: Livelihood Consequences of Dam Construction in Ethiopia
The concept of the water-energy-food (W-E-F) nexus has quickly ascended to become a global framing for resource management policies. Critical studies, however, are questioning its value for assessing the sustainability of local livelihoods. These critiques flow in part from the perception that the majority of influential nexus analyses begin from a large-scale, implicitly top-down perspective on resource dynamics. This can lead to eciency narratives that reinforce existing power dynamics without adequate consideration of local priorities. Here, we present a community-scale perspective on large W-E-F oriented infrastructure. In doing so, we link the current debate on the nexus with alternative approaches to embrace questions of water distribution, political scales, and resource management. The data for this paper come from a survey of 549 households conducted around two large-scale irrigation and hydropower dams in the Upper Blue Nile basin of Ethiopia. The data analysis involved descriptive statistics, logistic analysis, and multinomial logistic analysis.
The two case studies presented show that the impact of dams and the perception thereof is socially diverse. Hydropower dams and irrigation schemes tend to enhance social dierences and may therefore lead to social transformation and disintegration. This becomes critical when it leads to higher vulnerability of some groups. To take these social factors/conditions into consideration, one needs to acknowledge the science-policy interface and make the nexus approach more political. The paper concludes that if the nexus approach is to live up to its promise of addressing sustainable development goals by protecting the livelihoods of vulnerable populations, it has to be applied in a manner that addresses the underlying causes that produce winners and losers in large-scale water infrastructure developments
Shared molecular targets confer resistance over short and long evolutionary timescales
Pre-existing and de novo genetic variants can both drive adaptation to environmental changes, but their relative contributions and interplay remain poorly understood. Here we investigated the evolutionary dynamics in drug-treated yeast populations with different levels of pre-existing variation by experimental evolution coupled with time-resolved sequencing and phenotyping. We found a doubling of pre-existing variation alone boosts the adaptation by 64.1% and 51.5% in hydroxyurea and rapamycin respectively. The causative pre-existing and de novo variants were selected on shared targets: RNR4 in hydroxyurea and TOR1, TOR2 in rapamycin. Interestingly, the pre-existing and de novo TOR variants map to different functional domains and act via distinct mechanisms. The pre-existing TOR variants from two domesticated strains exhibited opposite rapamycin resistance effects, reflecting lineage-specific functional divergence. This study provides a dynamic view on how pre-existing and de novo variants interactively drive adaptation and deepens our understanding of clonally evolving populations
Intragenic repeat expansion in the cell wall protein gene HPF1 controls yeast chronological aging
Aging varies among individuals due to both genetics and environment, but the underlying molecular mechanisms remain largely unknown. Using a highly recombined Saccharomyces cerevisiae population, we found 30 distinct quantitative trait loci (QTLs) that control chronological life span (CLS) in calorie-rich and calorie-restricted environments and under rapamycin exposure. Calorie restriction and rapamycin extended life span in virtually all genotypes but through different genetic variants. We tracked the two major QTLs to the cell wall glycoprotein genes FLO11 and HPF1. We found that massive expansion of intragenic tandem repeats within the N-terminal domain of HPF1 was sufficient to cause pronounced life span shortening. Life span impairment by HPF1 was buffered by rapamycin but not by calorie restriction. The HPF1 repeat expansion shifted yeast cells from a sedentary to a buoyant state, thereby increasing their exposure to surrounding oxygen. The higher oxygenation altered methionine, lipid, and purine metabolism, and inhibited quiescence, which explains the life span shortening. We conclude that fast-evolving intragenic repeat expansions can fundamentally change the relationship between cells and their environment with profound effects on cellular lifestyle and longevity
Profile of opioid prescriptions for intubated and mechanically ventilated neonates
Objective: to identify factors that affect the decision of prescribing opioids for intubated and ventilated neonates Method: retrospective study of intubated and ventilated newborn infants for periods longer than one hour, admitted to the NICU from January 1995 to June 1997. During this period, 203 patients fulfilled inclusion criteria and data of 176 charts were reviewed. Charts were analyzed regarding demographic data, characteristics of analgesia and respiratory support, invasive procedures performed and clinical entities diagnosed during the period of mechanical ventilation. Discriminative analysis was used to understand factors that lead to opioid use by some of these patients. Results: Ninety-seven neonates received at least one dose of opioids during the period of mechanical ventilation. None of these patients was evaluated with pain scales, and in 63% of them we could not retrieve any reason for opioid prescription in their charts. Discriminative analysis showed that the main differences between groups were birthweight, gestational age, oxygenation index at intubation, and number of arterial sticks during the first 72 hours of mechanical ventilation. The most mature and heaviest neonates with a more severe respiratory insufficiency received opioid analgesia during ventilation. Conclusion: the decision to use opioids in intubated and ventilated neonates was based on the infants' aspect and respiratory status. It did not consider the pain these patients might be suffering and it was not based on the evaluation of pain.Objetivo: identificar fatores que levaram os médicos a prescreverem opióides a recém-nascidos em ventilação mecânica. Método: estudo retrospectivo de pacientes em ventilação mecânica por cânula traqueal, por mais de 1 hora, internados em UTI neonatal entre janeiro de 1995 a junho de 1997. Nesse perÃodo, 203 recém-nascidos preencheram o critério de inclusão, recuperando-se 176 prontuários. Os prontuários foram analisados quanto a dados demográficos, caracterÃsticas da analgesia e do suporte ventilatório, procedimentos invasivos realizados e entidades mórbidas diagnosticadas durante o perÃodo de ventilação. Para entender os fatores que determinaram o uso da analgesia em parte dessa população, utilizou-se a análise discriminante. Resultados: Nos 97 pacientes que receberam > 1 dose de opióides durante a ventilação, a analgesia foi iniciada, em média, até 24 horas após o inÃcio da ventilação. As escalas de avaliação da dor não foram usadas em nenhum paciente e, em 63%, não havia relato do motivo para a analgesia. A análise discriminante mostrou que as variáveis que diferenciaram os grupos submetidos ou não à analgesia foram: peso ao nascer, idade gestacional, Ãndice de oxigenação e número de punções arteriais. Os neonatos com maior chance de receberem alguma dose de opióide durante a ventilação foram os de peso mais elevado, idade gestacional mais avançada, Ãndice de oxigenação mais acentuado no inÃcio da ventilação e maior necessidade de gasometrias, ou seja, os bebês mais maduros e com doença respiratória mais grave. Conclusão: os médicos não levam em conta a dor propriamente dita e nem a avaliam para decidirem pela necessidade de analgesia no neonato em ventilaçãoUniversidade Federal de São Paulo (UNIFESP) - Escola Paulista de Medicina (UNIFESP-EPM)UNIFESP-EPM Disciplina de Pediatria NeonatalUNIFESP-EPM Disciplina de BioestatÃsticaUNIFESP, - Escola Paulista de Medicina (UNIFESP-EPM)UNIFESP, EPM Disciplina de Pediatria NeonatalUNIFESP, EPM Disciplina de BioestatÃsticaSciEL
The Peacock study:feasibility of the dynamic characterisation of the paediatric hypothalamic-pituitary-adrenal function during and after cardiac surgery
An amendment to this paper has been published and can be accessed via the original article
SPICE, A Dataset of Drug-like Molecules and Peptides for Training Machine Learning Potentials
Machine learning potentials are an important tool for molecular simulation,
but their development is held back by a shortage of high quality datasets to
train them on. We describe the SPICE dataset, a new quantum chemistry dataset
for training potentials relevant to simulating drug-like small molecules
interacting with proteins. It contains over 1.1 million conformations for a
diverse set of small molecules, dimers, dipeptides, and solvated amino acids.
It includes 15 elements, charged and uncharged molecules, and a wide range of
covalent and non-covalent interactions. It provides both forces and energies
calculated at the {\omega}B97M-D3(BJ)/def2-TZVPPD level of theory, along with
other useful quantities such as multipole moments and bond orders. We train a
set of machine learning potentials on it and demonstrate that they can achieve
chemical accuracy across a broad region of chemical space. It can serve as a
valuable resource for the creation of transferable, ready to use potential
functions for use in molecular simulations.Comment: 19 pages, 6 figure
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