152 research outputs found
Casimir-Polder shifts on quantum levitation states
An ultracold atom above a horizontal mirror experiences quantum reflection
from the attractive Casimir-Polder interaction, which holds it against gravity
and leads to quantum levitation states. We analyze this system by using a
Liouville transformation of the Schr\"odinger equation and a Langer coordinate
adapted to problems with a classical turning point. Reflection on the
Casimir-Polder attractive well is replaced by reflection on a repulsive wall
and the problem is then viewed as an ultracold atom trapped inside a cavity
with gravity and Casimir-Polder potentials acting respectively as top and
bottom mirrors. We calculate numerically Casimir-Polder shifts of the energies
of the cavity resonances and propose a new approximate treatment which is
precise enough to discuss spectroscopy experiments aiming at tests of the weak
equivalence principle on antihydrogen. We also discuss the lifetimes by
calculating complex energies associated with cavity resonances.Comment: Accepted in PR
Quantum reflection of antihydrogen from a liquid helium film
We study the quantum reflection of ultracold antihydrogen atoms bouncing on
the surface of a liquid helium film. The Casimir-Polder potential and quantum
reflection are calculated for different thicknesses of the film supported by
different substrates. Antihydrogen can be protected from anni- hilation for as
long as 1.3s on a bulk of liquid 4He, and 1.7s for liquid 3He. These large
lifetimes open interesting perspectives for spectroscopic measurements of the
free fall acceleration of antihydrogen. Variation of the scattering length with
the thickness of a film of helium shows interferences which we interpret
through a Liouville transformation of the quantum reflection problem
The Dynamics of Ecosystems, Biodiversity Management and Social Institutions at High Northern Latitudes
Ecosystems at high latitudes are highly dynamic, influenced
by a multitude of large-scale disturbances. Due to global
change processes these systems may be expected to be
particularly vulnerable, affecting the sustained production
of renewable wood resources and abundance of plants
and animals on which local cultures depend. In this paper,
we assess the implications of new understandings of high
northern latitude ecosystems and what must be done to
manage systems for resilience. We suggest that the focus
of land management should shift from recovery from local
disturbance to sustaining ecosystem functions in the face
of change and disruption. The role of biodiversity as insurance
for allowing a system to reorganize and develop during
the disturbance and reorganization phases needs to be
addressed in management and policy. We emphasize that
the current concepts of ecological reserves and protected
areas need to be reconsidered to developp dynamic tools
for sustainable management of ecosystems in face of
change. Characteristics of what may be considered as customary
reserves at high latitudes are often consistent with
a more dynamic view of reserves. We suggest new directions
for addressing biodiversity management in dynamic
landscapes at high latitudes, and provide empirical examples
of insights from unconventional perspectives that may
help improve the potential for sustainable management of
biodiversity and the generation of ecosystem services
Burnout syndrome among psychiatric trainees in 22 countries: Risk increased by long working hours, lack of supervision, and psychiatry not being first career choice
Background: Postgraduate medical trainees experience high rates of burnout, but evidence regarding psychiatric trainees is missing. We aim to determine burnout rates among psychiatric trainees, and identify individual, educational and work-related factors associated with severe burnout. Methods: In an online survey psychiatric trainees from 22 countries were asked to complete the Maslach Burnout Inventory (MBI-GS) and provide information on individual, educational and work-related parameters. Linear mixed models were used to predict the MBI-GS scores, and a generalized linear mixed model to predict severe burnout. Results: This is the largest study on burnout and training conditions among psychiatric trainees to date. Complete data were obtained from 1980 out of 7625 approached trainees (26%; range 17.8-65.6%). Participants were 31.9 (SD 5.3) years old with 2.8 (SD 1.9) years of training. Severe burnout was found in 726 (36.7%) trainees. The risk was higher for trainees who were younger (P < 0.001), without children (P = 0.010), and had not opted for psychiatry as a first career choice (P = 0.043). After adjustment for socio-demographic characteristics, years in training and country differences in burnout, severe burnout remained associated with long working hours (P < 0.001), lack of supervision (P < 0.001), and not having regular time to rest (P = 0.001). Main findings were replicated in a sensitivity analysis with countries with response rate above 50%. Conclusions: Besides previously described risk factors such as working hours and younger age, this is the first evidence of negative influence of lack of supervision and not opting for psychiatry as a first career choice on trainees' burnout
Integrating the Water Planetary Boundary With Water Management From Local to Global Scales
The planetary boundaries framework defines the "safe operating space for humanity" represented by nine global processes that can destabilize the Earth System if perturbed. The water planetary boundary attempts to provide a global limit to anthropogenic water cycle modifications, but it has been challenging to translate and apply it to the regional and local scales at which water problems and management typically occur. We develop a cross-scale approach by which the water planetary boundary could guide sustainable water management and governance at subglobal contexts defined by physical features (e.g., watershed or aquifer), political borders (e.g., city, nation, or group of nations), or commercial entities (e.g., corporation, trade group, or financial institution). The application of the water planetary boundary at these subglobal contexts occurs via two approaches: (i) calculating fair shares, in which local water cycle modifications are compared to that context's allocation of the global safe operating space, taking into account biophysical, socioeconomic, and ethical considerations; and (ii) defining a local safe operating space, in which interactions between water stores and Earth System components are used to define local boundaries required for sustaining the local water system in stable conditions, which we demonstrate with a case study of the Cienaga Grande de Santa Marta wetlands in Colombia. By harmonizing these two approaches, the water planetary boundary can ensure that water cycle modifications remain within both local and global boundaries and complement existing water management and governance approaches
Transnational corporations and the challenge of biosphere stewardship
This is the author accepted manuscript. The final version is available from Nature Research via the DOI in this recordSustainability within planetary boundaries requires concerted action by individuals, governments, civil society and private actors. For the private sector, there is concern that the power exercised by transnational corporations generates, and is even central to, global environmental change. Here, we ask under which conditions transnational corporations could either hinder or promote a global shift towards sustainability. We show that a handful of transnational corporations have become a major force shaping the global intertwined system of people and planet. Transnational corporations in agriculture, forestry, seafood, cement, minerals and fossil energy cause environmental impacts and possess the ability to influence critical functions of the biosphere. We review evidence of current practices and identify six observed features of change towards 'corporate biosphere stewardship', with significant potential for upscaling. Actions by transnational corporations, if combined with effective public policies and improved governmental regulations, could substantially accelerate sustainability efforts.Beijer FoundationErling-Persson Family FoundationMarianne and Marcus Wallenberg FoundationWalton Family FoundationDavid and Lucile Packard FoundationGordon and Betty Moore FoundationMistra: The Swedish Foundation for Strategic Environmental Researc
Triple Bottom Line or Trilemma? Global Tradeoffs Between Prosperity, Inequality, and the Environment
This is the final version. Available on open access from Elsevier via the DOI in this recordData availability: All data used in the paper is openly available. Replication code is provided on the GitHub repository
https://github.com/juanrocha/trilemma/A key aim of sustainable development is the joint achievement of prosperity, equality, and environmental integrity: in other words, material living standards that are high, broadly-distributed, and low-impact. This has often been called the âtriple bottom lineâ. But instead, what if there is a âtrilemmaâ that inhibits the simultaneous achievement of these three goals? We analysed international patterns and trends in the relationships between per-capita gross national income, the Gini coefficient for income distribution, and per-capita ecological footprint from 1995 to 2017, benchmarking them against thresholds from the existing literature. A âdynamicâ analysis of the trajectories of 59 countries and a âstaticâ analysis of a larger sample of 140 countries found that none met the triple bottom line, and that instead there were widespread tradeoffs among the three indicators. These tradeoffs, leading to divergent national trajectories and country clusters, show that common pair-wise explanations such as Kuznets Curves do not adequately capture important development dynamics. In particular, while only a few countries simultaneously met the thresholds for prosperity and equality on the one hand and equality and environment on the other, none did for prosperity and environment. Moreover, inequality likely makes resolving this critical tradeoff more difficult. Our findings suggest that mitigating the sustainability trilemma may require countries â especially those that are already prosperous â to prioritize economic redistribution and environmental stewardship over further growth.FormasSwedish Research Counci
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