30 research outputs found
Collaborate, compete and share
We introduce and study a model of an interacting population of agents who
collaborate in groups which compete for limited resources. Groups are formed by
random matching agents and their worth is determined by the sum of the efforts
deployed by agents in group formation. Agents, on their side, have to share
their effort between contributing to their group's chances to outcompete other
groups and resource sharing among partners, when the group is successful. A
simple implementation of this strategic interaction gives rise to static and
evolutionary properties with a very rich phenomenology. A robust emerging
feature is the coexistence in the population of agents who invest mainly in the
success of their group and agents who concentrate in getting the largest share
of their group's profits.Comment: 10 pages, 9 figures, published versio
A Theoretical Perspective on the Photochemistry of Boron-Nitrogen Lewis Adducts
Boron-Nitrogen (B-N) Lewis adducts form a versatile family of compounds with
numerous applications in functional molecules. Despite the growing interest in
this family of compounds for optoelectronic applications, little is currently
known about their photophysics and photochemistry. Even the electronic
absorption spectrum of ammonia borane, the textbook example of a B-N Lewis
adduct, is unavailable. Given the versatility of the light-induced processes
exhibited by these molecules, we propose in this work a detailed theoretical
study of the photochemistry and photophysics of simple B-N Lewis adducts. We
used advanced techniques in computational photochemistry to identify and
characterize the possible photochemical pathways followed by ammonia borane,
and extended this knowledge to the substituted B-N Lewis adducts
pyridine-borane and pyridine-boric acid. The photochemistry observed for this
series of molecules allows us to extract qualitative rules to rationalize the
light-induced behavior of more complex B-N containing molecules
A Theoretical Perspective on the Actinic Photochemistry of 2-Hydroperoxypropanal
[Image: see text] The photochemical reactions triggered by the sunlight absorption of transient volatile organic compounds in the troposphere are notoriously difficult to characterize experimentally due to the unstable and short-lived nature of these organic molecules. Some members of this family of compounds are likely to exhibit a rich photochemistry given the diversity of functional groups they can bear. Even more interesting is the photochemical fate of volatile organic compounds bearing more than one functional group that can absorb light—this is the case, for example, of α-hydroperoxycarbonyls, which are formed during the oxidation of isoprene. Experimental observables characterizing the photochemistry of these molecules like photoabsorption cross-sections or photolysis quantum yields are currently missing, and we propose here to leverage a recently developed computational protocol to predict in silico the photochemical fate of 2-hydroperoxypropanal (2-HPP) in the actinic region. We combine different levels of electronic structure methods—SCS-ADC(2) and XMS-CASPT2—with the nuclear ensemble approach and trajectory surface hopping to understand the mechanistic details of the possible nonradiative processes of 2-HPP. In particular, we predict the photoabsorption cross-section and the wavelength-dependent quantum yields for the observed photolytic pathways and combine them to determine in silico photolysis rate constants. The limitations of our protocol and possible future improvements are discussed
On the Theoretical Determination of Photolysis Properties for Atmospheric Volatile Organic Compounds
Volatile organic compounds (VOC) are ubiquitous atmospheric molecules that generate a complex network of chemical reactions in the troposphere, often triggered by the absorption of sunlight. Understanding the VOC composition of the atmosphere relies on our ability to characterize all of their possible reaction pathways. When considering reactions of (transient) VOCs with sunlight, the availability of photolysis rate constants, utilized in general atmospheric models, is often out of experimental reach due to the unstable nature of these molecules. Here, we show how recent advances in computational photochemistry allow us to calculate \textit{in silico} the different ingredients of a photolysis rate constant, namely the photoabsorption cross-section and wavelength-dependent quantum yields. The rich photochemistry of tert-butyl hydroperoxide, for which experimental data is available, is employed to test our protocol and highlight the strengths and weaknesses of different levels of electronic structure and nonadiabatic molecular dynamics to study the photochemistry of (transient) VOCs
Time Evolution of Plasmonic Features in Pentagonal Ag Clusters
In the present work, we apply recently developed real-time descriptors to study the time evolution of plasmonic features of pentagonal Ag clusters. The method is based on the propagation of the time-dependent Schrodinger equation within a singly excited TDDFT ansatz. We use transition contribution maps (TCMs) and induced density to characterize the optical longitudinal and transverse response of such clusters, when interacting with pulses resonant with the low-energy (around 2-3 eV, A(1)) size-dependent or the high-energy (around 4 eV, E-1) size-independent peak. TCMs plots on the analyzed clusters, Ag-25(+) and Ag-43(+) show off-diagonal peaks consistent with a plasmonic response when a longitudinal pulse resonant at A(1) frequency is applied, and dominant diagonal spots, typical of a molecular transition, when a transverse E-1 pulse is employed. Induced densities confirm this behavior, with a dipole-like charge distribution in the first case. The optical features show a time delay with respect to the evolution of the external pulse, consistent with those found in the literature for real-time TDDFT calculations on metal clusters
Peeking into the Femtosecond Hot-Carrier Dynamics Reveals Unexpected Mechanisms in Plasmonic Photocatalysis
Plasmonic-driven photocatalysis may lead to reaction selectivity that cannot be otherwise achieved. A fundamental role is played by hot carriers, i.e., electrons and holes generated upon plasmonic decay within the metal nanostructure interacting with molecular species. Understanding the elusive microscopic mechanism behind such selectivity is a key step in the rational design of hot-carrier reactions. To accomplish that, we present state-of-the-art multiscale simulations, going beyond density functional theory, of hot-carrier injections for the rate-determining step of a photocatalytic reaction. We focus on carbon dioxide reduction, for which it was experimentally shown that the presence of a rhodium nanocube under illumination leads to the selective production of methane against carbon monoxide. We show that selectivity is due to a (predominantly) direct hole injection from rhodium to the reaction intermediate CHO. Unexpectedly, such an injection does not promote the selective reaction path by favoring proper bond breaking but rather by promoting bonding of the proper molecular fragment to the surface
Defining the causes of sporadic Parkinson's disease in the global Parkinson's genetics program (GP2)
The Global Parkinson’s Genetics Program (GP2) will genotype over 150,000 participants from around the world, and integrate genetic and clinical data for use in large-scale analyses to dramatically expand our understanding of the genetic architecture of PD. This report details the workflow for cohort integration into the complex arm of GP2, and together with our outline of the monogenic hub in a companion paper, provides a generalizable blueprint for establishing large scale collaborative research consortia
Multi-ancestry genome-wide association meta-analysis of Parkinson?s disease
Although over 90 independent risk variants have been identified for Parkinson’s disease using genome-wide association studies, most studies have been performed in just one population at a time. Here we performed a large-scale multi-ancestry meta-analysis of Parkinson’s disease with 49,049 cases, 18,785 proxy cases and 2,458,063 controls including individuals of European, East Asian, Latin American and African ancestry. In a meta-analysis, we identified 78 independent genome-wide significant loci, including 12 potentially novel loci (MTF2, PIK3CA, ADD1, SYBU, IRS2, USP8, PIGL, FASN, MYLK2, USP25, EP300 and PPP6R2) and fine-mapped 6 putative causal variants at 6 known PD loci. By combining our results with publicly available eQTL data, we identified 25 putative risk genes in these novel loci whose expression is associated with PD risk. This work lays the groundwork for future efforts aimed at identifying PD loci in non-European populations