Advantageous Leadership in Public Good Provision: The Case of an Endogenous Contribution Technology

From the perspective of standard public good theory the total amount of greenhouse gas mitigation (or public good supply in general) will be lower in a leader-follower game than in a simultaneous Nash game so that strategic leadership is disadvantageous for climate policy. We show that this need no longer be true when the leading country has the option to employ a technology by which it can reduce its abatement costs and thus improve the productivity of its contribution technology. Our general result is illustrated by an example with Cobb-Douglas preferences and, finally, an empirical application to global climate policy is briefly discussed

Advantageous Leadership in Public Good Provision: The Case of an Endogenous Contribution Technology

From the perspective of standard public good theory the total amount of greenhouse gas mitigation (or public good supply in general) will be lower in a leader-follower game than in a simultaneous Nash game so that strategic leadership is disadvantageous for climate policy. We show that this need no longer be true when the leading country has the option to employ a technology by which it can reduce its abatement costs and thus improve the productivity of its contribution technology

Technological Transfers in Global Climate Policy

Theoretical analysis and empirical evidence show that leadership behavior in climate policy through increased abatement efforts or international transfers cannot be expected to be very successful. In this paper we instead show that pioneering activities, which are based on green technological innovations carried out by a coalition of countries, may be a better approach for combatting global warming through unilateral action. In particular, we examine in an otherwise standard model of private public good supply how the success of such a policy depends on the intensity and scope of technological spillovers

Maximum rates of climate change are systematically underestimated in the geological record

D.B.K. was supported by NERC Fellowship grant NE/I02089X/1 and W.K. by DFG grant Ki 806/12-1. Jonny Beedell is thanked for his help in data compilation and Michael Joachimski for discussions.Peer reviewedPublisher PD

Optical fibers with interferometric path length stability by controlled heating for transmission of optical signals and as components in frequency standards

We present a simple method to stabilize the optical path length of an optical fiber to an accuracy of about 1/100 of the laser wavelength. We study the dynamic response of the path length to modulation of an electrically conductive heater layer of the fiber. The path length is measured against the laser wavelength by use of the Pound-Drever-Hall method; negative feedback is applied via the heater. We apply the method in the context of a cryogenic resonator frequency standard.Comment: Expanded introduction and outlook. 9 pages, 5 figure

Evaluation of the ultimate performances of a Ca+ single-ion frequency standard

We numerically evaluate the expected performances of an optical frequency standard at 729 nm based on a single calcium ion. The frequency stability is studied through the Allan deviation and its dependence on the excitation method (single Rabi pulse or two Ramsey pulses schemes) and the laser linewidth are discussed. The minimum Allan deviation that can be expected is estimated to $\sigma_y(\tau) \approx 2.5\times 10^{-15}/\sqrt{\tau}$ with $\tau$ the integration time. The frequency shifts induced by the environmental conditions are evaluated to minimize the uncertainty of the proposed standard by chosing the most suited environment for the ion. If using the odd isotope $^{43}$Ca$^{+}$ and a vessel cooled to 77 K, the expected relative shift is $-2 \times 10^{-16}$ with an uncertainty of $\pm 4\times10^{-16}$, mainly due to the quadrupole shift induced by the unknown static electric field gradient .Comment: soumis le 27/07/04 a Physics Letters

Leadership in social dilemmas

The objective of this thesis is to assess the prospects of leadership in the provision of public goods like climate change mitigation theoretically and empirically. The thesis is divided in four major sections. The theoretical Section I is based on classical narrow payoff maximizing economic agents and makes use of the Aggregative Game Approach (Cornes and Hartley 2007, Cornes 2016). Chapter 1 considers pioneering behaviour in coalition building and the resulting incentive effect on another group to form a coalition whereas Chapter 2 sheds light on the effects that technology transfers exert on the choice of a contribution technology by a group of countries. Chapter 3 addresses the question whether the sequential provision of a public good (in a Stackelberg game) increases public good supply as compared to simultaneous provision (in a Nash game) if one of two countries has the possibility to adopt an improved contribution technology. The theoretical analysis in Section I is complemented in Section II by an empirical example concerning leadership in technological progress of solar energy through its subsidization in Germany. The two remaining parts then move away from narrow payoff-maximizing agents. Both in public discussion and economic literature reciprocity is regarded as a key to successful cooperation and successful leadership. Consequently, Section III addresses the scope of reciprocity in economic experiments as well as in international relations (Chapter 5). Chapter 6 then investigates in an online experiment on MTurk the within-subject stability of reciprocal patterns across classification methods using a sequential public goods game (Fischbacher et al. 2001) on the one hand and a sequential prisoner’s dilemma (e.g. Miettinen et al. 2017) on the other hand. The final Section IV deals with the question whether it can be expected that leading-by-example is able to increase public good supply. A meta-analysis of the existing literature in Chapter 7 as well as a lab experiment that incorporates leadership in a dynamic public goods game with endowment carryover (Gächter et al. 2017) in Chapter 8 provide some answers to this question

Uneven spatial sampling distorts reconstructions of Phanerozoic seawater temperature

Paleotemperature proxy records are widely used to reconstruct the global climate throughout the Phanerozoic and to test macroevolutionary hypotheses. However, the spatial distribution of these records varies through time. This is problematic because heat is unevenly distributed across Earth's surface. Consequently, heterogeneous spatial sampling of proxy data has the potential to bias reconstructed temperature curves. We evaluated the spatiotemporal evolution of sampling using a compilation of Phanerozoic δ18O data. We tested the influence of variable spatial coverage on global estimates of paleotemperature by sampling a steep “modern-type” latitudinal temperature gradient and a flattened “Eocene-type” gradient, based on the spatial distribution of δ18O samples. We show that global paleotemperature is overestimated in ∼70% of Phanerozoic stages. Perceived climatic trends for some intervals might be artifactually induced by shifts in paleolatitudinal sampling, with equatorward shifts in sampling concurring with warming trends, and poleward shifts concurring with cooling trends. Yet, the magnitude of some climatic perturbations might also be underestimated. For example, the observed Ordovician cooling trend may be underestimated due to an equatorward shift in sampling. Our findings suggest that while proxy records are vital for reconstructing Earth's paleotemperature in deep time, consideration of the spatial nature of these data is crucial to improving these reconstructions

Theory and applications of atomic and ionic polarizabilities

Atomic polarization phenomena impinge upon a number of areas and processes in physics. The dielectric constant and refractive index of any gas are examples of macroscopic properties that are largely determined by the dipole polarizability. When it comes to microscopic phenomena, the existence of alkaline-earth anions and the recently discovered ability of positrons to bind to many atoms are predominantly due to the polarization interaction. An imperfect knowledge of atomic polarizabilities is presently looming as the largest source of uncertainty in the new generation of optical frequency standards. Accurate polarizabilities for the group I and II atoms and ions of the periodic table have recently become available by a variety of techniques. These include refined many-body perturbation theory and coupled-cluster calculations sometimes combined with precise experimental data for selected transitions, microwave spectroscopy of Rydberg atoms and ions, refractive index measurements in microwave cavities, ab initio calculations of atomic structures using explicitly correlated wave functions, interferometry with atom beams, and velocity changes of laser cooled atoms induced by an electric field. This review examines existing theoretical methods of determining atomic and ionic polarizabilities, and discusses their relevance to various applications with particular emphasis on cold-atom physics and the metrology of atomic frequency standards.Comment: Review paper, 44 page