Mining the Common Heritage of Our DNA: Lessons Learned From Grotius and Pardo

The Human Genome Project generated oceans of DNA sequence data and spurred a multinational race to grab the bounties of these oceans. In response to these DNA property grabs, UNESCO, drawing upon international law precedents addressing analogous grabs in the past, declared the Human Genome the heritage of humanity. The UNESCO Declaration provided, first, that the heritage shall not, in its natural state, give rise to financial gains and, second, that countries establish an international framework to make the benefits from genome research available to all. This iBrief will first examine Grotius’s Mare Liberum to determine whether international law precedent indeed bars the private appropriation of a common heritage. Second, the iBrief will revisit the framework developed by Pardo for the exploitation of the mineral resources of the ocean floor and analyze whether it could serve as a model for an international framework for sharing the benefits of current genome research

Climate models miss most of the coarse dust in the atmosphere.

Coarse mineral dust (diameter, ≥5 μm) is an important component of the Earth system that affects clouds, ocean ecosystems, and climate. Despite their significance, climate models consistently underestimate the amount of coarse dust in the atmosphere when compared to measurements. Here, we estimate the global load of coarse dust using a framework that leverages dozens of measurements of atmospheric dust size distributions. We find that the atmosphere contains 17 Tg of coarse dust, which is four times more than current climate models simulate. Our findings indicate that models deposit coarse dust out of the atmosphere too quickly. Accounting for this missing coarse dust adds a warming effect of 0.15 W·m-2 and increases the likelihood that dust net warms the climate system. We conclude that to properly represent the impact of dust on the Earth system, climate models must include an accurate treatment of coarse dust in the atmosphere

Efficient computation of updated lower expectations for imprecise continuous-time hidden Markov chains

We consider the problem of performing inference with imprecise continuous-time hidden Markov chains, that is, imprecise continuous-time Markov chains that are augmented with random output variables whose distribution depends on the hidden state of the chain. The prefix `imprecise' refers to the fact that we do not consider a classical continuous-time Markov chain, but replace it with a robust extension that allows us to represent various types of model uncertainty, using the theory of imprecise probabilities. The inference problem amounts to computing lower expectations of functions on the state-space of the chain, given observations of the output variables. We develop and investigate this problem with very few assumptions on the output variables; in particular, they can be chosen to be either discrete or continuous random variables. Our main result is a polynomial runtime algorithm to compute the lower expectation of functions on the state-space at any given time-point, given a collection of observations of the output variables

Bayesian Optimization with Unknown Constraints

Recent work on Bayesian optimization has shown its effectiveness in global optimization of difficult black-box objective functions. Many real-world optimization problems of interest also have constraints which are unknown a priori. In this paper, we study Bayesian optimization for constrained problems in the general case that noise may be present in the constraint functions, and the objective and constraints may be evaluated independently. We provide motivating practical examples, and present a general framework to solve such problems. We demonstrate the effectiveness of our approach on optimizing the performance of online latent Dirichlet allocation subject to topic sparsity constraints, tuning a neural network given test-time memory constraints, and optimizing Hamiltonian Monte Carlo to achieve maximal effectiveness in a fixed time, subject to passing standard convergence diagnostics.Comment: 14 pages, 3 figure

Tailoring optical response of a hybrid comprising a quantum dimer emitter strongly coupled to a metal nanoparticle

We study theoretically the optical response of a nanohybrid comprising a symmetric quantum dimer emitter coupled to a metal nanoparticle (MNP). The interactions between the exitonic transitions in the dimer and the plasmons in the MNP lead to novel effects in the composite's input-output characteristics for the light intensity and the absorption spectrum, which we study in the linear and nonlinear regimes. We fnd that the exciton-plasmon hybridization leads to optical bistability and hysteresis for the one-exciton transition and enhancement of excitation for the two-exciton transition. The latter leads to a signifcant decrease of the field strength needed to saturate the system. In the linear regime, the absortion spectrum has a dispersive (Fano-like) line shape. The spectral position and shape of this spectrum depend on the detuning of the dimer's one-exciton resonance relative to the plasmon resonance. Upon increasing the applied field intensity to the nonlinear regime, the Fano-like singularities in the absorption spectra are smeared and they disappear due to the saturation of the dimer, which leads to the MNP dominating the spectrum. The above effects, for which we provide physical explanations, allow one to tailor the Fano-like shape of the absorption spectrum, by changing either the detuning or the input power

Trapping time statistics and efficiency of transport of optical excitations in dendrimers

We theoretically study the trapping time distribution and the efficiency of the excitation energy transport in dendritic systems. Trapping of excitations, created at the periphery of the dendrimer, on a trap located at its core, is used as a probe of the efficiency of the energy transport across the dendrimer. The transport process is treated as incoherent hopping of excitations between nearest-neighbor dendrimer units and is described using a rate equation. We account for radiative and non-radiative decay of the excitations while diffusing across the dendrimer. We derive exact expressions for the Laplace transform of the trapping time distribution and the efficiency of trapping and analyze those for various realizations of the energy bias, number of dendrimer generations, and relative rates for decay and hopping. We show that the essential parameter that governs the trapping efficiency, is the product of the on-site excitation decay rate and the trapping time (mean first passage time) in the absence of decay.Comment: 26 pages, 6 figure

Evolution of AGN Space Densities and the FR Dichotomy

We focus on a comparison of the space densities of FRI and FRII extended radio sources at different epochs, and find that FRI and FRII sources show similar space density enhancements in various redshift ranges, possibly implying a common evolution.Comment: IAU Symposium 267 Proceeding - 1 pag

Plasmon-assisted two-photon Rabi oscillations in a semiconductor quantum dot -- metal nanoparticle heterodimer

Tho-photon Rabi oscillations hold potential for quantum computing and quantum information processing, because during a Rabi cycle a pair of entangled photons may be created. We theoretically investigate the onset of this phenomenon in a heterodimer comprising a semiconductor quantum dot strongly coupled to a metal nanoparticle. Two-photon Rabi oscillations in this system occur due to a coherent two-photon process involving the ground-to-biexciton transition in the quantum dot. The presence of a metal nanoparticle nearby the quantum dot results in a self-action of the quantum dot via the metal nanoparticle, because the polatization state of the latter depends on the quantum state of the former. The interparticle interaction gives rise to two principal effects: (i) - enhancement of the external field amplitude and (ii) - renormalization of the quantum dot's resonance frequencies and relaxation rates of the off-diagonal density matrix elements, both depending on the populations of the quantum dot's levels. Here, we focus on the first effect, which results in interesting new features, in particular, in an increased number of Rabi cycles per pulse as compared to an isolated quantum dot and subsequent growth of the number of entangled photon pairs per pulse. We also discuss the destructive role of radiative decay of the excitonic states on two-photon Rabi oscillations for both an isolated quantum dot and a heterodimer.Comment: 11 pages, 19 figure