Ambiguity, Optimism, and Pessimism in Adverse Selection Models

We investigate the effect of ambiguity and ambiguity attitude on the shape and properties of the optimal contract in an adverse selection model with a continuum of types, using the parametric model of ambiguity and ambiguity aversion called the NEO-additive model (Chateauneuf, Eichberger, and Grant, 2007). We show that it necessarily features efficiency and a jump at the top and pooling at the bottom of the distribution. Conditional on the degree of ambiguity, the pooling section may or may not be supplemented by a separating section. As a result, ambiguity adversely affects the principal’s ability to solve the adverse selection problem and therefore the least efficient types benefit from ambiguity with respect to risk. Conversely, ambiguity is detrimental to the most efficient types. This is confirmed in the comparative statics section

La moralité kantienne a-t-elle une fin ?

La moralité kantienne n’a pas de fin au sens d’un motif matériel puisque cette activité se définit comme celle qui est motivée seulement par le concept du devoir. Mais elle a une fin au sens d’un concept matériel qui, sans motiver la volonté, guide celle-ci. La morale kantienne présente donc un aspect non seulement déontologique, mais téléologique

La doctrine kantienne du bien et du souverain bien.

Even though the question of the highest good and what it consists in lay at the basis of the Ancients ' moral systems, it seems to have gone out of fashion in the Modern era. However, according to Kant, man cannot will anything but under the idea of good and, in order to be able to bring the series of his ends to a close, he needs to conceive the idea of an unconditioned end of his, the "highest good". By tackling the problem of the universal meaning of human life, Kant pays tribute to an ancient approach to practical philosophy in which the latter, in its teleological aspect, teaches man what the absolutely necessary end of his conduct must consist in and how he can attain it. As a result, he builds a doctrine of the summum bonum, following in the Ancients' footsteps, the conclusion of which doctrine lies in the answer to philosophy's two pratical questions. What may I hope (the question concerning the essence of the highest good)? What am I to do (the question concerning the conduct resulting in the highest good)? But the Copernican Revolution in ethics is the discovery that the concept of the good and that of the highest good are determined by the moral law. Kantian ethics formulates the moral law first, and defines the good and the highest good later, in the converse order from that in which the Ancients operated. This original method is responsible for a theory that opposes ancient ethics in many ways. It leads Kant to the idea that human ends are heterogeneous and that the highest good is a synthesis based on a relation of subordination, i.e., happiness conditioned by morality.Même si la question du souverain bien et de ce qui le constitue était au fondement des systèmes moraux des Anciens, elle semble n'être plus à l'ordre du jour pour nous, les Modernes. Pourtant, nous dit Kant, l'homme ne peut rien vouloir si ce n'est sous l'idée d'une fin et il a besoin, pour pouvoir mettre un terme à la série de ses fins, de concevoir un inconditionné, une fin « architectonique» sienne, dont le nom est le « souverain bien ». En abordant à nouveau la question du sens universel de la vie humaine, Kant adhère à une conception antique de la philosophie pratique dans laquelle celle-ci, en tant que téléologie morale, enseigne à l'homme en quoi doit consister la fin absolument nécessaire de sa conduite et comment il peut l'atteindre. Il élabore donc, comme les Anciens, une théorie du "summum bonum" dont le point d'orgue est la réponse aux deux questions pratiques de la philosophie. Que puis-je espérer (question de l'essence du souverain bien) ? Que dois-je faire (question de la conduite menant au souverain bien) ? Mais la Révolution copernicienne consiste, en éthique, à découvrir que le concept du bien et celui du bien le plus grand sont déterminés par la loi morale. La morale kantienne formule d'abord la loi morale, pour ensuite définir le bien et le souverain bien, tandis que les Anciens faisaient l'inverse. Ces points de méthode sont responsables d'une théorie qui s'oppose aux morales antiques par plusieurs aspects. Elle conduit à l'idée d'une hétérogénéité de fins humaines qui implique une conception du souverain bien comme une synthèse contenant un rapport de subordination, le bonheur conditionné par la moralité

Structure and dynamics in protic ionic liquids: a combined optical Kerr-effect and dielectric relaxation spectroscopy study

The structure and dynamics of ionic liquids (ILs) are unusual due to the strong interactions between the ions and counter ions. These microscopic properties determine the bulk transport properties critical to applications of ILs such as advanced fuel cells. The terahertz dynamics and slower relaxations of simple alkylammonium nitrate protic ionic liquids (PILs) are here studied using femtosecond optical Kerr-effect spectroscopy, dielectric relaxation spectroscopy, and terahertz time-domain spectroscopy. The observed dynamics give insight into more general liquid behaviour while comparison with glass-forming liquids reveals an underlying power-law decay and relaxation rates suggest supramolecular structure and nanoscale segregation

Highly Ordered Titanium Dioxide Nanostructures via a Simple One Step Vapor Inclusion Method in Block Copolymer Films

Nanostructured crystalline titanium dioxide (TiO2) finds applications in numerous fields such as photocatalysis or photovoltaics where its physical and chemical properties depend on its shape and crystallinity. We report a simple method of fabricating TiO2 nanowires by selective area deposition of titanium tetraisopropoxide (TTIP) and water in a CVD-based approach at low temperature by utilizing PS-b-PEO self-assembled block copolymer thin film as a template. Parameters such as exposure time to TTIP (minutes to hours), working temperature (~18 to 40 °C) and relative humidity (20 to 70 RH%) were systemically investigated through GISAXS, SEM and XPS and optimized for fabrication of TiO2 nanostructures. The resulting processing conditions yielded titanium dioxide nanowires with a diameter of 24 nm. An extra calcination step (400 – 700 °C) was introduced to burn off the remaining organic matrix and introduce phase change from amorphous to anatase in TiO2 nanowires without any loss in order

Subsurface ablation of atherosclerotic plaque using ultrafast laser pulses

We perform subsurface ablation of atherosclerotic plaque using ultrafast pulses. Excised mouse aortas containing atherosclerotic plaque were ablated with ultrafast near-infrared (NIR) laser pulses. Optical coherence tomography (OCT) was used to observe the ablation result, while the physical damage was inspected in histological sections. We characterize the effects of incident pulse energy on surface damage, ablation hole size, and filament propagation. We find that it is possible to ablate plaque just below the surface without causing surface damage, which motivates further investigation of ultrafast ablation for subsurface atherosclerotic plaque removal

Ultrafast laser ablation for targeted atherosclerotic plaque removal

Coronary artery disease, the main cause of heart disease, develops as immune cells and lipids accumulate into plaques within the coronary arterial wall. As a plaque grows, the tissue layer (fibrous cap) separating it from the blood flow becomes thinner and increasingly susceptible to rupturing and causing a potentially lethal thrombosis. The stabilization and/or treatment of atherosclerotic plaque is required to prevent rupturing and remains an unsolved medical problem. Here we show for the first time targeted, subsurface ablation of atherosclerotic plaque using ultrafast laser pulses. Excised atherosclerotic mouse aortas were ablated with ultrafast near-infrared (NIR) laser pulses. The physical damage was characterized with histological sections of the ablated atherosclerotic arteries from six different mice. The ultrafast ablation system was integrated with optical coherence tomography (OCT) imaging for plaque-specific targeting and monitoring of the resulting ablation volume. We find that ultrafast ablation of plaque just below the surface is possible without causing damage to the fibrous cap, which indicates the potential use of ultrafast ablation for subsurface atherosclerotic plaque removal. We further demonstrate ex vivo subsurface ablation of a plaque volume through a catheter device with the high-energy ultrafast pulse delivered via hollow-core photonic crystal fiber

Tunable electromagnetic resonant shunt using pulse-width modulation

This article proposes a novel mean for tuning the natural frequency of an electromagnetic resonant shunt, using a pulse-width modulation (PWM) circuit. It is used to modulate the value of the capacitance of the shunt, and the electrical frequency is shown to be proportional to the command parameter of the PWM, the duty cycle. An easy and efficient strategy to tune the resonant shunt in real time is then proposed, thus obtaining a low powered and always stable vibration control device. The article proposes the theory of PWM, giving a robust method to predict the dynamics of the system. Then, an accurate multi-mode theoretical model of the tunable resonant shunt coupled to an elastic structure is proposed and experimentally validated on an elastic multi-mode structure, in the case of two different control strategies. The first one is a standard resonant shunt with both the electrical frequency and damping optimized to reduce a given resonance peak. The second one is based on a resonant shunt with the electrical damping as low as possible, which creates an antiresonance and a “notch” type mechanical response at the driving frequency. Both strategies are experimentally validated with real time variation and adaptation of the electrical frequency, obtaining an efficient vibration control device, able to reduce by a factor 40 the vibration level

Improved resistive shunt by means of negative capacitance: new circuit, performances and multi-mode control

This paper deals with vibration control by means of piezoelectric patches shunted with electrical impedances made up by a resistance and a negative capacitance. The paper analyses most of the possible layouts by which a negative capacitance can be built and shows that a common mathematical description is possible. This allows closed formulations to be found in order to optimise the electrical network for mono- and multi-mode control. General analytical formulations are obtained to estimate the performance of the shunt in terms of vibration reduction. In particular, it is highlighted that the main effect of a negative capacitance is to artificially enhance the electromechanical coupling factor, which is the basis of performance estimation. Stability issues relating to the use of negative capacitances are especially addressed using refined models for the piezoelectric patch capacitance. Furthermore, a new circuit based on a couple of negative capacitances is proposed and tested, showing better performances than those provided by the usual layouts with a single negative capacitance. Finally, guidelines and analytical formulations to deal with the practical implementation of negative capacitance circuits are provided

A new electrical circuit with negative capacitances to enhance resistive shunt damping

This article proposes a new layout of electrical network based on two negative capacitance circuits, aimed at increasing the performances of a traditional resistive piezoelectric shunt for structural vibration reduction. It is equivalent to artificially increase the modal electromechanical coupling factor of the electromechanical structure by both decreasing the short-circuit natural frequencies and increasing the open-circuit ones. This leads to higher values of the modal electromechanical coupling factor with respect to simple negative capacitance configurations, when the same margin from stability is considered. This technique is shown to be powerful in enhancing the control performance when associated to a simple resistive shunt, usually avoided because of its poor performances