Reform der EU-Milchmarktpolitik bei instabilen Weltmärkten

The article examines the market and welfare effects of the current CAP reform and further policy options on the EU dairy market. The main focus is the influence of unstable world markets and the uncertainty it generates in policy analysis which has been widely neglected. The simulations of a stochastic dairy market model reveal that the considered policy options affect the impact of world market instabilities on the EU dairy market. Thus, not only a changing level of producer price or revenues can be expected, but also a changing degree of instability. Policy making without taking such instability changes into account may lead to undesired effects and, finally, could undermine the realisation of policy objectives. Also, the evaluation of the welfare effects of the policy options is more sophisticated than in a deterministic examination. With respect to the assessment of the CAP reform the simulations show that its impact on the EU dairy market instability as well as on the uncertainty of the welfare effects depends crucially on whether the quota is binding or not.CAP, dairy market, milk quota system, partial equilibrium model, uncertainty, stochastic simulation, Agricultural and Food Policy, Livestock Production/Industries,

Quantification of the Downstream Impact of Extratropical Transition for Typhoon Jangmi and Other Case Studies

The impact of extratropical transition on the midlatitude flow is quantified based on potential vorticity inversion. The detailed study of Typhoon Jangmi (2008) reveals the diabatically enhanced net transport of low-PV air to the tropopause as the key physical process determining the direct impact of ET. Relocation experiments and further case studies show the crucial role of the relative position of the TC and the midlatitude flow for the downstream impact of ET and the reduced predictability

Are “New Urban” Neighborhood Design Characteristics Associated with Greater Levels of Social Capital within Neighborhoods? : Evidence from Greenville, South Carolina

Proponents of “new urbanism” suggest that “new urban” neighborhood design characteristics promote social interaction within the neighborhood. In this paper we formally analyze the relationship between “new urban” neighborhood characteristics (e.g., grid street patterns, green space, mixed commercial and residential land use) and social capital formation. We conducted a survey in order to determine the presence of new urban characteristics in neighborhoods and levels of neighborhood-specific social capital in Greenville, South Carolina. We then constructed a social capital index, which we regressed against a set of new urban and control variables. We find that new urban characteristics which facilitate personal interactions are correlated with the social capital index, as are the “youthfulness” of the neighborhood, homeownership rates, fewer hours worked, and the presence of children 18 and under in the household. These results suggest that some aspects of new urbanism may help promote the development of social capital within neighborhoods

Quantification of the downstream impact of extratropical transition for Typhoon Jangmi and other case studies

The impact of extratropical transition on the midlatitude flow is quantified based on potential vorticity inversion. The detailed study of Typhoon Jangmi (2008) reveals the diabatically enhanced net transport of low-PV air to the tropopause as the key physical process determining the direct impact of ET. Relocation experiments and further case studies show the crucial role of the relative position of the TC and the midlatitude flow for the downstream impact of ET and the reduced predictability

DRAMA at the PettingZoo: Dynamically restricted action spaces for multi-agent reinforcement learning frameworks

The Agent Environment Cycle (AEC) of PettingZoo has been a major paradigm shift in the implementation of Multi-Agent Reinforcement Learning (MARL) frameworks, providing a unified and concise interface for any kind of multi-agent environment. Based on this model, we propose DRAMA, a principled approach for dynamic action space restrictions. DRAMA can be used to add statically computed physical constraints as well as a self-learning multi-agent governance: It generalizes the idea of action masking to continuous action spaces and self-learning restrictions, while being fully compatible with the AEC implementation of PettingZoo—and, by transitivity, with most major MARL frameworks. In this paper, we provide the theoretical background of restricted multi-agent systems, present an extension of PettingZoo via wrapper classes, and show the potential of our approach for various use cases. By treating dynamic restrictions as an additional player of a multi-agent system, our approach offers novel capabilities and flexibility in handling multi-agent environments and thus serves as a valuable tool for researchers and practitioners in the field

Similarity and variability of blocked weather-regime dynamics in the Atlantic-European region

Weather regimes govern an important part of the sub-seasonal variability of the mid-latitude circulation. Due to their role in weather extremes and atmospheric predictability, regimes that feature a blocking anticyclone are of particular interest. This study investigates the dynamics of these ''blocked'' regimes in the North Atlantic-European region from a year-round perspective. For a comprehensive diagnostic, we combine wave activity concepts and a piecewise potential-vorticity (PV) tendency framework. The latter essentially quantifies the well-established PV perspective of mid-latitude dynamics. All blocked regimes during the 1979&ndash;2021 period of ERA5 reanalysis are considered. Wave activity characteristics exhibit distinct differences between blocked regimes. After regime onset, one regime (Greenland Blocking) is associated with a suppression of wave activity flux, whereas two other regimes (Atlantic Ridge and European Blocking) are associated with a northward deflection of the flux without a clear net change. During onset, the envelope of Rossby wave activity retracts upstream for Greenland Blocking, whereas the envelope extends downstream for Atlantic Ridge and European Blocking. The fourth regime (Scandinavian Blocking) exhibits intermediate wave activity characteristics. From the perspective of piecewise PV tendencies projected onto the respective regime pattern, the dynamics that govern regime onset exhibit a large degree of similarity: Linear Rossby wave dynamics and nonlinear eddy PV fluxes dominate and are of approximately equal relative importance, whereas baroclinic coupling and divergent amplification make minor contributions. Most strikingly, all blocked regimes exhibit very similar (intra-regime) variability: a retrograde and an upstream pathway to regime onset. The retrograde pathway is dominated by nonlinear PV eddy fluxes, whereas the upstream pathway is dominated by linear Rossby wave dynamics. Importantly, there is a large degree of cancellation between the two pathways for some of the mechanisms before regime onset. The physical meaning of a regime-mean perspective before onset can thus be severely limited. Implications of our results for understanding predictability of blocked regimes are discussed. We further discuss the limitations of projected tendencies in capturing the importance of moist processes, which tend to occur at the fringes or outside of the regime pattern. Finally, we stress that this study investigate the variability of the governing dynamics without prior empirical stratification of data by season or by type of regime transition. We demonstrate, however, that our dynamics-centered approach does not map predominantly on variability that is associated with these factors. The main modes of dynamical variability revealed herein, and the large similarity of the blocked regimes in exhibiting this variability are thus significant results.</p

Lifetime Risk of Lower-Extremity Peripheral Artery Disease Defined by Ankle-Brachial Index in the United States.

Background There are no available lifetime risk estimates of lower-extremity peripheral artery disease (PAD). Methods and Results Using data from 6 US community-based cohorts and the vital statistics, we estimated the prevalence and incidence of PAD, defined as an ankle-brachial index&nbsp;&lt;&nbsp;0.90, at each year of age from birth to 80&nbsp;years for white, black, and Hispanic men and women. Then, we used Markov Monte Carlo simulations in a simulated cohort of 100&nbsp;000 individuals to estimate lifetime risk of PAD. On the basis of odds ratios of PAD for traditional atherosclerotic risk factors (eg, diabetes mellitus and smoking), we developed a calculator providing residual lifetime risk of PAD. In an 80-year horizon, lifetime risks of PAD were 30.0% in black men and 27.6% in black women, but ≈19% in white men and women and ≈22% in Hispanic men and women. From another perspective, 9% of blacks were estimated to develop PAD by 60&nbsp;years of age, while the same proportion was seen at ≈70&nbsp;years for whites and Hispanics. The residual lifetime risk within the same race/ethnicity varied by 3.5- to 5-fold according to risk factors (eg, residual lifetime risk in 45-year-old black men was 19.9% when current smoking, diabetes mellitus, and history of cardiovascular disease were absent versus 70.4% when all were present). Conclusions In the United States, ≈30% of blacks are estimated to develop PAD during their lifetime, whereas the corresponding estimate is ≈20% for whites and Hispanics. The residual lifetime risk within the same race/ethnicity substantially varies according to traditional risk factors

RAISE the bar: Restriction of action spaces for improved social welfare and equity in traffic management

Restriction-based governance has recently been proposed as an alternative to reward shaping for achieving system-level goals in competitive multi-agent systems. In this work, we apply these two approaches to the domain of traffic management, specifically investigating their efficacy and fairness. Our results show that edge restrictions in congested traffic networks are superior to dynamic pricing with regard to equity (i.e., equal treatment of agents) while achieving comparable travel-time improvements. We argue that the former metric, as an adequate proxy for fairness, can be crucial for the quality and acceptance of a governance scheme, particularly when human agents are affected