1,601 research outputs found
Thermal Gradient Changes Caused by Water in the Soil
The heat flow density data published in the Geothermal Atlas of Europe (1992) show relatively high values for temperature gradients measured in holes in the SW area (Portugal and Spain) of the Iberian Peninsula.
This study tries to explain this fact based in the presence of water at relatively high temperatures outside the holes where the measurements were made, and the inclination of strata, derived from samples taken from the boreholes. We used a two-dimensional numerical model based on the finite volume method. Equations governing the transfer of energy by conduction and advection and fluid flow, were solved.
Thermal conductivity values of the rocks and water may vary spatially as well as the porosity. Thermal conductivity values were measured but values of the hydraulic conductivity and porosity are unknown. Due to this fact, the models are tested with different values of these parameters.
The heat flow density value considered for the region is 60 mWm-2 and the thermal gradient is calculated using the value of thermal conductivity. The results obtained with the models are compared with those published. Different solutions can be obtained for a given hole
MedellĂn in the headlines: The role of the media in the dissemination of urban models
The circulation of ideas about âbest practicesâ and policies shape multi-scalar governance networks. This paper examines the role of the international press, both as an actor and as a medium for the circulation of urban planning models. We aim to deepen the theoretical notions on the role of media, particularly the written press, in building narratives of âurban modelsâ, and their circulation in other contexts. And second, by extending the reaches of multi-sited ethnography as the main methodological approach to follow policy mobility. This research monitored, and analysed news items published about MedellĂn on the digital editions of several newspapers across the globe between 2004 and 2017. The resulting examination shows, firstly, how the changes of the image of the city has been portrayed over time, with a growth of news items highlighting MedellĂn's urban model as an inspirational source for other cities in the world. Secondly, the research shows the importance of international media for building a particular storytelling about urban transformations. We argue that newspapers constitute a key informational infrastructure for urban policy mobility contributing to amplify mythical narratives of âurban modelsâ and to institute new metrics of good governance
Emergent modified gravity: Covariance regained
In its canonical formulation, general relativity is subject to gauge
transformations that are equivalent to space-time coordinate changes of general
covariance only when the gauge generators, given by the Hamiltonian and
diffeomorphism constraints, vanish. Since the specific form taken by Poisson
brackets of the constraints and of the gauge transformations and equations of
motion they generate is important for general covariance to be realized,
modifications of the canonical theory, suggested for instance by approaches to
quantum gravity, are not guaranteed to be compatible with the existence of a
covariant space-time line element. This caveat applies even if the modification
preserves the number of independent gauge transformations and the modified
constraints remain first class. Here, a complete derivation of covariance
conditions, regained from the canonical constraints without assuming that
space-time has its classical structure, is presented and applied in detail to
spherically symmetric vacuum models. As a broad application, the presence of
structure functions in the constraint brackets plays a crucial role, which in
an independent analysis has recently been shown to lead to higher algebraic
structures in hypersurface deformations given by an L-infinity bracket. The
physical analysis of a related feature presented here demonstrates that, at
least within the spherically symmetric setting, new theories of modified
gravity are possible that are not of higher-curvature form.Comment: 50 page
Challenging Bourdieu's Theory: Dialogic Interaction as a Means to Provide Access to Highbrow Culture for All
According to Bourdieu, class position is related to cultural capital, taste, and preferences. Accordingly, the author states that, because of their 'habitus,' those from high social classes have higher cultural capital and preferences for highbrow culture, which gives them more chances to succeed in life. On the contrary, those from low social classes have lower cultural capital because of their lowbrow cultural preferences, which makes it more difficult for them to achieve in a system that favors the dominant classes. Through the review of articles on Dialogic Literary Gatherings published in peer-reviewed journals, this article aims to provide more insights on how the principles of dialogic learning occur. The results of the review challenge Bourdieu's concept of 'habitus,' providing evidence of how socioeconomic status (SES) is not determinant to cultural capital
Response of a particle in a one-dimensional lattice to an applied force: Dynamics of the effective mass
We study the behaviour of the expectation value of the acceleration of a
particle in a one-dimensional periodic potential when an external homogeneous
force is suddenly applied. The theory is formulated in terms of modified Bloch
states that include the interband mixing induced by the force. This approach
allows us to understand the behaviour of the wavepacket, which responds with a
mass that is initially the bare mass, and subsequently oscillates around the
value predicted by the effective mass. If Zener tunneling can be neglected, the
expression obtained for the acceleration of the particle is valid over
timescales of the order of a Bloch oscillation, which are of interest for
experiments with cold atoms in optical lattices. We discuss how these
oscillations can be tuned in an optical lattice for experimental detection.Comment: 15 pages, 12 figure
TWINLATIN: Twinning European and Latin-American river basins for research enabling sustainable water resources management. Combined Report D3.1 Hydrological modelling report and D3.2 Evaluation report
Water use has almost tripled over the past 50 years and in some regions the water demand already
exceeds supply (Vorosmarty et al., 2000). The world is facing a âglobal water crisisâ; in many
countries, current levels of water use are unsustainable, with systems vulnerable to collapse from even
small changes in water availability. The need for a scientifically-based assessment of the potential
impacts on water resources of future changes, as a basis for society to adapt to such changes, is strong
for most parts of the world. Although the focus of such assessments has tended to be climate change,
socio-economic changes can have as significant an impact on water availability across the four main
use sectors i.e. domestic, agricultural, industrial (including energy) and environmental. Withdrawal
and consumption of water is expected to continue to grow substantially over the next 20-50 years
(Cosgrove & Rijsberman, 2002), and consequent changes in availability may drastically affect society
and economies.
One of the most needed improvements in Latin American river basin management is a higher level of
detail in hydrological modelling and erosion risk assessment, as a basis for identification and analysis
of mitigation actions, as well as for analysis of global change scenarios. Flow measurements are too
costly to be realised at more than a few locations, which means that modelled data are required for the
rest of the basin. Hence, TWINLATIN Work Package 3 âHydrological modelling and extremesâ was
formulated to provide methods and tools to be used by other WPs, in particular WP6 on âPollution
pressure and impact analysisâ and WP8 on âChange effects and vulnerability assessmentâ. With an
emphasis on high and low flows and their impacts, WP3 was originally called âHydrological
modelling, flooding, erosion, water scarcity and water abstractionâ. However, at the TWINLATIN
kick-off meeting it was agreed that some of these issues resided more appropriately in WP6 and WP8,
and so WP3 was renamed to focus on hydrological modelling and hydrological extremes.
The specific objectives of WP3 as set out in the Description of Work are
The effect of training and experience on mass casualty incident triage performance: Evidence from emergency personnel in a high complexity university hospital
Mass casualty incident (MCI) can occur at any time and place and health care institutions must be prepared to deal with these incidents. Emergency department staff rarely learn how to triage MCI patients during their medical or nurse degrees, or through on-the-job training. This study aims to evaluate the effect of training and experience on the MCI triage performance of emergency personnel. METHODOLOGY: This was a cross-sectional prospective study that analyzed the performance of 94 emergency department staff on the triage classifications of 50 trauma patients, before and after a short training in MCI triage, while taking into account their academic background and work experience. RESULTS: The participants were assigned initially to one of two groups: low experience if they had less than 5 years of practice, and high experience if they had more than 5 years of practice. In the low experience group, the initial accuracy was 45.76 percent, over triage 45.84 percent, and subtriage 8.38 percent. In the high experience group, the initial accuracy was 53.80 percent, over triage 37.66 percent, and sub triage 8.57 percent. POSTINTERVENTION RESULTS: In the low experience group, the post intervention accuracy was 63.57 percent, over triage 21.15 percent, and subtriage 15.30 percentage. In the high experience group, the postintervention accuracy was 67.66 percentage, over triage 15.19 percentage, and subtriage 17.14 percentage. CONCLUSION: Upon completion of this study, it can be concluded that MCI triage training significantly improved the performance of all those involved in the workshop and that experience plays an important role in MCI triage performance
New insights on satisfaction prototypes for segmentation
This paper tests a conceptual segmentation using a criterion outlined by Oliver based on the satisfaction prototypes customers may follow. The empirical study was conducted with a sample of theme park visitors grouped into four satisfaction prototypes/segments. Results show the presence of important differences by groups in terms of both the effects of perceived value dimensions on satisfaction and the level of satisfaction by segment, supporting the proposed approach. The findings are valuable for a better identification of key drivers of segments' satisfaction, which will be helpful to redesign service experiences to better fit the varying preferences of modern consumers
Contribution to EPMA to airbone pollen analysis
As a component of aerosol, pollen is found in suspension with other mineralogical and anthropogenic particles that can adhere to the pollen wall. The aim of
this study was to determine possible alterations that pollen grains suffer under different meteorological conditions in the coastal city of Porto, Portugal. For
this study, 2 airborne pollen types were taken into account: Poaceae and Alnus spp sampled in July 2010 and February 2011, respectively. Quantitative
analysis and X-ray map analysis were performed with a Field Emission Electron Probe Microanalyser (EPMA). Samples were mounted over adhesive carbon tape
and carbon coated. Control pollen showed mainly the presence of C, O, N, P, K, Mg, S, Cl and Ca in different quantities, depending on the considered species.
Airborne pollen consistently revealed a higher content of Mg and Cl than control pollen, while Si, Ca, K and P contents varied differently according to the
samples. Our results show that during their âflightâ, pollen grains acquire an external coating, become heavier and change significantly their composition
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