Exciton-exciton interaction engineering in coupled GaN quantum dots

We present a fully three-dimensional study of the multiexciton optical response of vertically coupled GaN-based quantum dots via a direct-diagonalization approach. The proposed analysis is crucial in understanding the fundamental properties of few-particle/exciton interactions and, more important, may play an essential role in the design/optimization of semiconductor-based quantum information processing schemes. In particular, we focus on the interdot exciton-exciton coupling, key ingredient in recently proposed all-optical quantum processors. Our analysis demonstrates that there is a large window of realistic parameters for which both biexcitonic shift and oscillator strength are compatible with such implementation schemes.Comment: 3 two-column pages, 3 figure

Destrucció dels "boscos animals" del fons del mar

L'anomenat "bosc animal", compost per gorgònies, coralls, esponges i altres organismes que viuen fixos al fons del mar, és un ecosistema amb importants funcions dins el conjunt dels oceans que està en seriós declivi a tot el planeta. La pesca, i concretament la pesca d'arrossegament, és la principal pertorbació d'aquests ecosistemes, ja que "escombra" el fons del mar i el despulla de flora i fauna. Aquest article intenta explicar els principals motius de la seva ràpida desaparició i degradació, així com per què no s'està fent res efectiu per conservar-los.El llamado "bosque animal", compuesto por gorgonias, corales, esponjas y otros organismos que viven fijos en el fondo del mar, es un ecosistema con importantes funciones dentro del conjunto de los océanos que está en serio declive en todo el planeta. La pesca, y concretamente la pesca de arrastre, es la principal perturbación de estos ecosistemas, pues "barre" el fondo del mar y lo despoja de flora y fauna. Este artículo intenta explicar los principales motivos de su rápida desaparición y degradación, así como por qué no se está haciendo nada efectivo para conservarlos

The Labor Market Return to an Attractive Face: Evidence from a Field Experiment

We provide new evidence on the link between beauty and hiring practices in the labor market. Specifically, we study if people with less attractive faces are less likely to be contacted after submitting a resume. Our empirical strategy is based on an experimental approach. We sent fictitious resumes with pictures of attractive and unattractive faces to real job openings in Buenos Aires, Argentina. We find that attractive people receive 36 percent more responses (callbacks) than unattractive people. Given the experimental design, this difference can be attributed to the exogenous manipulation of facial attractiveness of our fake job applicants.facial attractiveness, callback rates, labor market discrimination

Efficient Importance Sampling Maximum Likelihood Estimation of Stochastic Differential Equations

This paper considers ML estimation of a diffusion process observed discretely. Since the exact loglikelihood is generally not available, it must be approximated. We review the most efficient approaches in the literature, and point to some drawbacks. We propose to approximate the loglikelihood using the EIS strategy (Richard and Zhang, 1998), and detail its implementation for univariate homogeneous processes. Some Monte Carlo experiments evaluate its performance against an alternative IS strategy (Durham and Gallant, 2002), showing that EIS is at least equivalent, if not superior, while allowing a greater flexibility needed when examining more complicated models

The bud break process and its variation among local populations of boreal black spruce

Phenology of local populations can exhibit adaptations to the current environmental conditions resulting from a close interaction between climate and genotype. The bud break process and its variations among populations were analyzed in greenhouse by monitoring the growth resumption in black spruce [Picea mariana (Mill.) BSP] seedlings originating from seeds of five stands across the closed boreal forest in Quebec, Canada. Bud break lasted 15 days and occurred earlier and quicker in northern provenances. Provenance explained between 10.2 and 32.3% of the variance in bud break, while the families accounted for a smaller but still significant part of the variance. The late occurrence of one phenological phase corresponded to a delayed occurrence of the others according to linear relationships. A causal model was proposed in the form of a chain of events with each phase of bud break being related to the previous and successive one, while no link was observed between non-adjacent phases. The adaptation of black spruce populations along the latitudinal gradient points toward a strategy based on rapid physiological processes triggered by temperature increase inducing high metabolic activity. The variation observed in bud break reflects an evolutionary trade-off between maximization of security and taking advantage of the short growing season. This work provides evidence of the phenological adaptations of black spruce to its local environmental conditions while retaining sizeable genetic diversity within populations. Because of the multigenic nature of phenology, this diversity should provide some raw material for adaptation to changing local environmental conditions

Money, income, and profit: lessons from the monetary theory of production

In this paper we analyze Augusto Graziani’s numerous contributions to the monetary theory of production, which he developed from a theoretical but also a policy-oriented perspective. We focus on the rejection of the neoclassical dichotomy, the causal relation between production and money creation, and the definition of macroeconomic saving. These three dimensions of Graziani’s work can be identified in the framework of the monetary circuit, in the tradition of classical and Marxian economic thought. The outcome of Graziani’s investigations sheds light on the working of a monetary economy of production from the issuance of bank money to the distribution of income and capital accumulation.In this paper we analyze Augusto Graziani’s numerous contributions to the monetary theory of production, which he developed from a theoretical but also a policy-oriented perspective. We focus on the rejection of the neoclassical dichotomy, the causal relation between production and money creation, and the definition of macroeconomic saving. These three dimensions of Graziani’s work can be identified in the framework of the monetary circuit, in the tradition of classical and Marxian economic thought. The outcome of Graziani’s investigations sheds light on the working of a monetary economy of production from the issuance of bank money to the distribution of income and capital accumu-lation