3,584 research outputs found
Assessing the volcanic hazard for Rome. 40Ar/39Ar and In-SAR constraints on the most recent eruptive activity and present-day uplift at Colli Albani Volcanic District
We present new 40Ar/39Ar data which allow us to refine the recurrence time for the most recent eruptive activity occurred at Colli Albani Volcanic District (CAVD) and constrain its geographic area. Time elapsed since the last eruption (36 kyr) overruns the recurrence time (31 kyr) in the last 100 kyr. New interferometric synthetic aperture radar data, covering the years 1993–2010, reveal ongoing inflation with maximum uplift rates (>2 mm/yr) in the area hosting the most recent (<200 ka) vents, suggesting that the observed uplift might be caused by magma injection within the youngest plumbing system. Finally, we frame the present deformation within the structural pattern of the area of Rome, characterized by 50 m of regional uplift since 200 ka and by geologic evidence for a recent (<2000 years) switch of the local stress-field, highlighting that the precursors of a new phase of volcanic activity are likely occurring at the CAVD
Data-driven models for microscopic vehicle emissions
In this paper, a new approach for describing the relationship between tailpipe emissions and vehicle movement variables is presented, called generalized additive model for location, scale and shape (GAMLSS). The dataset for this model is second-by-second emission laboratory measurements, following a real driving cycle that were recorded in urban, suburban and motorway areas of London. The GAMLSS emission model estimates each of CO_{2}, CO and NO_{x} in each second for two different vehicle types (petrol or diesel) using instantaneous speed and acceleration as the explanatory variables. Comparing the results with current emission models indicates substantial improvement in accuracy and quality of estimation by this approach
Variations in primary production and particulate carbon flux through the base of the euphotic zone at the site of the Sediment Trap Intercomparison Experiment (Panama Basin)
C primary production data collected during the deployment and recovery cruises of STIE in 1979 showed a simple relationship with light and nutrient concentrations in the euophotic zone. A simple empirical relationship, calibrated using these data, was derived so that weekly averaged observations of fractional cloudiness, sea-surface temperature and mixed layer depth could be used to estimate primary production on a weekly basis for the years 1976–1979. 15N-uptake measurements, which estimate new production, were combined with the 14C data to estimate particulate carbon fluxes from the euphotic zone. Results of calculations showed that production may vary by a factor of three and particulate carbon flux by a factor of ten on a week to week basis with peak values corresponding to times when the mixed layer became enriched in nutrients. Mean euphotic zone production and particulate carbon flux estimated for the STIE deployment cruise were 286 and 138 mg C m–2 d–1, respectively; they were 174 and 59 mg C m–2 d–1 for the recovery cruise. Mean production and flux values were 261 and 122 mg C m–2 d–1, respectively for the duration of STIE. Three high production and particle sedimentation events may have occurred during STIE in September and October 1979. 1979 appeared to be a year of lower than average primary production compared with 1976 and 1977
Groundwater seepage landscapes from distant and local sources in experiments and on Mars
© 2014 Author(s). Valleys with theater-shaped heads can form due to the seepage of groundwater and as a result of knickpoint (waterfall) erosion generated by overland flow. This ambiguity in the mechanism of formation hampers the interpretation of such valleys on Mars, particularly since there is limited knowledge of material properties. Moreover, the hydrological implications of a groundwater or surface water origin are important for our understanding of the evolution of surface features on Mars, and a quantification of valley morphologies at the landscape scale may provide diagnostic insights on the formative hydrological conditions. However, flow patterns and the resulting landscapes produced by different sources of groundwater are poorly understood. We aim to improve the understanding of the formation of entire valley landscapes through seepage processes from different groundwater sources that will provide a framework of landscape metrics for the interpretation of such systems. We study groundwater seepage from a distant source of groundwater and from infiltration of local precipitation in a series of sandbox experiments and combine our results with previous experiments and observations of the Martian surface. Key results are that groundwater flow piracy acts on valleys fed by a distant groundwater source and results in a sparsely dissected landscape of many small and a few large valleys. In contrast, valleys fed by a local groundwater source, i.e., nearby infiltration, result in a densely dissected landscape. In addition, valleys fed by a distant groundwater source grow towards that source, while valleys with a local source grow in a broad range of directions and have a strong tendency to bifurcate, particularly on flatter surfaces. We consider these results with respect to two Martian cases: Louros Valles shows properties of seepage by a local source of groundwater and Nirgal Vallis shows evidence of a distant source, which we interpret as groundwater flow from Tharsis
Flexible Causal Inference for Political Science
Measuring the causal impact of state behavior on outcomes is one of the biggest methodological challenges in the field of political science, for two reasons: behavior is generally endogenous, and the threat of unobserved variables that confound the relationship between behavior and outcomes is pervasive. Matching methods, widely considered to be the state of the art in causal inference in political science, are generally ill-suited to inference in the presence of unobserved confounders. Heckman-style multiple-equation models offer a solution to this problem; however, they rely on functional-form assumptions that can produce substantial bias in estimates of average treatment effects. We describe a category of models, flexible joint likelihood models, that account for both features of the data while avoiding reliance on rigid functional-form assumptions. We then assess these models’ performance in a series of neutral simulations, in which they produce substantial (55% to
90%) reduction in bias relative to competing models. Finally, we demonstrate their utility in a reanalysis of Simmons’ (2000) classic study of the impact of Article VIII commitment on compliance with the IMF’s currency-restriction regime
Double-lumen endotracheal tube for percutaneous tracheostomy: in vitro and in vivo preliminary data
Humour and laughter in meetings: influence, decision-making and the emergence of leadership
Recent constructions view leadership as a process of social influence which coordinates processes of change. Moreover, such processes are not necessarily linked to role hierarchy but may be emergent and distributed within teams. However, the micro-processes through which this occurs are not well understood. The significance of the paper lies in its contribution to an understanding of the emergence of leadership in teams, and in particular how humour and laughter are drawn on as a resource by which to exert social influence. Here, we use the construct of the play frame, ‘non serious’ talk in which participants jointly construct extended humorous sequences as improvisations, to analyse how team members manoeuvre in order to accomplish influence, decision-making and leadership. In taking this approach we are not concerned with considerations of how managers use jokes to exercise control, or workers use humour to subvert management. Rather, we examine how humour, and particularly the laughter it engenders, can contribute to an understanding of organizations as centred on communication and founded on the precept that organizations are ‘talked into being’. Here we show how talk in a play frame institutes a context which can be utilised by participants to exert influence and we demonstrate the highly contingent and contextual nature of the emergence of leadership within teams
Avaliação do crescimento vegetativo em cafeeiro arábica e sua dependência com fatores climáticos no Estado de Goiás.
Objetivou-se avaliar o crescimento vegetativo em Coffea arabica e relacioná-lo com os fatores climáticos, tendo como base o crescimento sazonal dos ramos ortotrópicos e plagiotrópicos, com diferentes idades, em condições irrigadas e não irrigadas, sujeitos as alterações climáticas e ao déficit hídrico no Cerrado Goiano.Conpeex 2010
Conditional Adversarial Camera Model Anonymization
The model of camera that was used to capture a particular photographic image
(model attribution) is typically inferred from high-frequency model-specific
artifacts present within the image. Model anonymization is the process of
transforming these artifacts such that the apparent capture model is changed.
We propose a conditional adversarial approach for learning such
transformations. In contrast to previous works, we cast model anonymization as
the process of transforming both high and low spatial frequency information. We
augment the objective with the loss from a pre-trained dual-stream model
attribution classifier, which constrains the generative network to transform
the full range of artifacts. Quantitative comparisons demonstrate the efficacy
of our framework in a restrictive non-interactive black-box setting.Comment: ECCV 2020 - Advances in Image Manipulation workshop (AIM 2020
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