73 research outputs found
Dynamic impacts of a financial reform of the CAP on regional land use, income and overall growth
http://ageconsearch.umn.edu/handle/4364
A description of the neutralino observables in terms of projectors
Applying Jarlskog's treatment of the CKM matrix, to the neutralino mass
matrix in MSSM for real soft gaugino SUSY breaking and -parameters, we
construct explicit analytical expressions for the four projectors which acting
on any neutralino state project out the mass eigenstates. Analytical
expressions for the neutralino mass eigenvalues in terms of the various SUSY
parameters, are also given. It is shown that these projectors and mass
eigenvalues are sufficient to describe any physical observable involving
neutralinos, to any order of perturbation theory. As an example, the cross section at tree level is given in
terms of these projectors. The expected magnitude of their various matrix
elements in plausible SUSY scenarios is also discussed.Comment: 14 pages, no figures. Version to appear in Phys. Rev. D. e-mail:
[email protected]
Mode analysis of numerical geodynamo models
It has been suggested in Hoyng (2009) that dynamo action can be analysed by
expansion of the magnetic field into dynamo modes and statistical evaluation of
the mode coefficients. We here validate this method by analysing a numerical
geodynamo model and comparing the numerically derived mean mode coefficients
with the theoretical predictions. The model belongs to the class of
kinematically stable dynamos with a dominating axisymmetric, antisymmetric with
respect to the equator and non-periodic fundamental dynamo mode. The analysis
requires a number of steps: the computation of the so-called dynamo
coefficients, the derivation of the temporally and azimuthally averaged dynamo
eigenmodes and the decomposition of the magnetic field of the numerical
geodynamo model into the eigenmodes. For the determination of the theoretical
mode excitation levels the turbulent velocity field needs to be projected on
the dynamo eigenmodes. We compare the theoretically and numerically derived
mean mode coefficients and find reasonably good agreement for most of the
modes. Some deviation might be attributable to the approximation involved in
the theory. Since the dynamo eigenmodes are not self-adjoint a spectral
interpretation of the eigenmodes is not possible
Supersymmetric dark matter in M31: can one see neutralino annihilation with CELESTE?
It is widely believed that dark matter exists within galaxies and clusters of
galaxies. Under the assumption that this dark matter is composed of the
lightest, stable supersymmetric particle, assumed to be the neutralino, the
feasibility of its indirect detection via observations of a diffuse gamma-ray
signal due to neutralino annihilations within M31 is examined. To this end,
first the dark matter halo of the close spiral galaxy M31 is modeled from
observations, then the resultant gamma-ray flux is estimated within
supersymmetric model configurations. We conclude that under favorable
conditions such as the rapid accretion of neutralinos on the central black hole
in M31 and/or the presence of many clumps inside its halo with inner
profiles, a neutralino annihilation gamma-ray signal is marginally detectable
by the ongoing collaboration CELESTE.Comment: Latex, 32 pages, 12 figures, 5 table
On the external forcing of global eruptive activity in the past 300 years
The decryption of the temporal sequence of volcanic eruptions is a key step
in better anticipating future events. Volcanic activity is the result of a
complex interaction between internal and external processes, with time scales
spanning multiple orders of magnitude. We review periodicities that have been
detected or correlated with volcanic eruptions/phenomena and interpreted as
resulting from external forces. Taking a global perspective and longer time
scales than a few years, we approach this interaction by analyzing three time
series using singular spectral analysis: the global number of volcanic
eruptions (NVE) between 1700 and 2022, the number of sunspots (ISSN), a proxy
for solar activity, the polar motion (PM) and length of day (lod), two proxies
for gravitational force. Several pseudo-periodicities are common to NVE and
ISSN, in addition to the 11-year Schwabe cycle that has been reported in
previous work, but NVE shares even more periodicities with PM. These
quasi-periodic components range from ~5 to ~130 years. We interpret our
analytical results in light of the Laplace's paradigm and propose that,
similarly to the movement of Earth's rotation axis, global eruptive activity is
modulated by commensurable orbital moments of the Jovian planets, whose
influence is also detected in solar activity
A protocol to develop shared socio-economic pathways for European agriculture
Moving towards a more sustainable future requires concerted actions, particularly in the context of global climate change. Integrated assessments of agricultural systems (IAAS) are considered valuable tools to provide sound information for policy and decision-making. IAAS use storylines to define socio-economic and environmental framework assumptions. While a set of qualitative global storylines, known as the Shared Socio-economic Pathways (SSPs), is available to inform integrated assessments at large scales, their spatial resolution and scope is insufficient for regional studies in agriculture. We present a protocol to operationalize the development of Shared Socio-economic Pathways for European agriculture â Eur-Agri-SSPs â to support IAAS. The proposed design of the storyline development process is based on six quality criteria: plausibility, vertical and horizontal consistency, salience, legitimacy, richness and creativity. Trade-offs between these criteria may occur. The process is science-driven and iterative to enhance plausibility and horizontal consistency. A nested approach is suggested to link storylines across scales while maintaining vertical consistency. Plausibility, legitimacy, salience, richness and creativity shall be stimulated in a participatory and interdisciplinary storyline development process. The quality criteria and process design requirements are combined in the protocol to increase conceptual and methodological transparency. The protocol specifies nine working steps. For each step, suitable methods are proposed and the intended level and format of stakeholder engagement are discussed. A key methodological challenge is to link global SSPs with regional perspectives provided by the stakeholders, while maintaining vertical consistency and stakeholder buy-in. We conclude that the protocol facilitates systematic development and evaluation of storylines, which can be transferred to other regions, sectors and scales and supports inter-comparisons of IAAS
Where is the EU headed given its current climate policy? A stakeholder-driven model inter-comparison.
Recent calls to do climate policy research with, rather than for, stakeholders have been answered in non-modelling science. Notwithstanding progress in modelling literature, however, very little of the scenario space traces back to what stakeholders are ultimately concerned about. With a suite of eleven integrated assessment, energy system and sectoral models, we carry out a model inter-comparison for the EU, the scenario logic and research questions of which have been formulated based on stakeholders' concerns. The output of this process is a scenario framework exploring where the region is headed rather than how to achieve its goals, extrapolating its current policy efforts into the future. We find that Europe is currently on track to overperforming its pre-2020 40% target yet far from its newest ambition of 55% emissions cuts by 2030, as well as looking at a 1.0-2.35 GtCO2 emissions range in 2050. Aside from the importance of transport electrification, deployment levels of carbon capture and storage are found intertwined with deeper emissions cuts and with hydrogen diffusion, with most hydrogen produced post-2040 being blue. Finally, the multi-model exercise has highlighted benefits from deeper decarbonisation in terms of energy security and jobs, and moderate to high renewables-dominated investment needs
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