9,375 research outputs found
Are the dimensions of private information more multiple than expected? Information asymmetries in the market of supplementary private health insurance in England
Our study reexamines standard econometric approaches for the detection of information asymmetries on insurance markets. We claim that evidence based on a standard framework with 2 equations, which uses potential sources of information asymmetries, should stress the importance of heterogeneity in the parameters. We argue that conclusions derived from this methodology can be misleading if the estimated coefficients in such an `unused characteristics' framework are driven by different parts of the population.
We show formally that an individual's expected risk from the perspective of insurance, conditioned on certain characteristics (which are not used for calculating the risk premium), can equal the population's expectation in risk { although such characteristics are both related to risk and insurance probability, which is usually interpreted as an indicator of information asymmetries.
We provide empirical evidence on the existence of information asymmetries in the market for supplementary private health insurance in the UK. Overall, we found evidence for advantageous selection into the private risk pool; ie people with lower health risk tend to insure more. The main drivers of this phenomenon seem to be characteristics such as income and wealth. Nevertheless, we also found parameter heterogeneity to be relevant, leading to possible misinterpretation if the standard `unused characteristics' approach is applied
Quantum measurement of the degree of polarization of a light beam
We demonstrate a coherent quantum measurement for the determination of the
degree of polarization (DOP). This method allows to measure the DOP in the
presence of fast polarization state fluctuations, difficult to achieve with the
typically used polarimetric technique. A good precision of the DOP measurements
is obtained using 8 type II nonlinear crystals assembled for spatial walk-off
compensation.Comment: 4 pages, 3 figure
Ecosystem properties and principles of living systems as foundation for sustainable agriculture – Critical reviews of environmental assessment tools, key findings and questions from a course process
With increasing demands on limited resources worldwide, there is a growing interest in sustainable patterns of utilisation and production. Ecological agriculture is a response to these concerns.
To assess progress and compliance, standard and comprehensive measures of resource requirements, impacts and agro-ecological health are needed. Assessment tools should also be rapid, standardized, userfriendly, meaningful to public policy and applicable to management. Fully considering these requirements confounds the development of integrated methods.
Currently, there are many methodologies for monitoring performance, each with its own foundations, assumptions, goals, and outcomes, dependent upon agency agenda or academic orientation. Clearly, a concept of sustainability must address biophysical, ecological, economic, and sociocultural foundations.
Assessment indicators and criteria, however, are generally limited, lacking integration, and at times in conflict with one another. A result is that certification criteria, indicators, and assessment methods are not based on a consistent, underlying conceptual framework and often lack a management focus.
Ecosystem properties and principles of living systems, including self-organisation, renewal, embeddedness, emergence and commensurate response provide foundation for sustainability assessments and may be appropriate focal points for critical thinking in an evaluation of current methods and standards. A systems framework may also help facilitate a comprehensive approach and promote a context for meaningful discourse. Without holistic accounts, sustainable progress remains an illdefined concept and an elusive goal.
Our intent, in the work with this report, was to use systems ecology as a pedagogic basis for learning and discussion to:
- Articulate general and common characteristics of living systems.
- Identify principles, properties and patterns inherent in natural ecosystems.
- Use these findings as foci in a dialogue about attributes of sustainability to:
a. develop a model for communicating scientific rationale.
b. critically evaluate environmental assessment tools for application in land-use.
c. propose appropriate criteria for a comprehensive assessment and expanded definition of ecological land use
Time-dependent exchange-correlation hole and potential of the electron gas
The exchange-correlation hole and potential of the homogeneous electron gas
have been investigated within the random-phase approximation, employing the
plasmon-pole approximation for the linear density response function. The
angular dependence as well as the time dependence of the exchange-correlation
hole are illustrated for a Wigner-Seitz radius (atomic unit). It is
found that there is a substantial cancellation between exchange and correlation
potentials in space and time, analogous to the cancellation of exchange and
correlation self-energies. Analysis of the sum rule explains why it is more
advantageous to use a non-interacting Green function than a renormalized one
when calculating the response function within the random-phase approximation
and consequently the self-energy within the well-established
approximation. The present study provides a starting point for more accurate
and comprehensive calculations of the exchange-correlation hole and potential
of the electron gas with the aim of constructing a model based on the local
density approximation as in density functional theory.Comment: 19 pages, 15 figure
Assessing the EU’s global climate change leadership: From Copenhagen to the Paris agreement
The EU has attempted to take a leading role in climate negotiations, but how effective has it been in shaping agreements? Charles F. Parker and Christer Karlsson present survey evidence from eight climate summits leading up to the Paris agreement in 2015. They highlight that although the EU’s perception of itself as a world leader was not shared to the same extent outside of the EU, it was still perceived to be one of the key leaders alongside China and the US
Calculations of Hubbard U from first-principles
The Hubbard \emph{U} of the \emph{3d} transition metal series as well as
SrVO, YTiO, Ce and Gd has been estimated using a recently proposed
scheme based on the random-phase approximation. The values obtained are
generally in good accord with the values often used in model calculations but
for some cases the estimated values are somewhat smaller than those used in the
literature. We have also calculated the frequency-dependent \emph{U} for some
of the materials. The strong frequency dependence of \emph{U} in some of the
cases considered in this paper suggests that the static value of \emph{U} may
not be the most appropriate one to use in model calculations. We have also made
comparison with the constrained LDA method and found some discrepancies in a
number of cases. We emphasize that our scheme and the constrained LDA method
theoretically ought to give similar results and the discrepancies may be
attributed to technical difficulties in performing calculations based on
currently implemented constrained LDA schemes.Comment: 24 pages, 13 figures; Submitted to Phys. Rev.
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