NNLO QED contribution to the μe→μe\mu e\to \mu e elastic scattering

We present the current status of the Next-to-Next-to-Leading Order QED contribution to the $\mu e$-scattering. Particular focus is given to the techniques involved to tackle the virtual amplitude and their automatic implementation. Renormalization of the amplitude will be also discuss in details.Comment: 9 pages, 5 figures, contribution to the Workshop on "Flavour changing and conserving processes" 2019 (FCCP2019), 29-31 August 2019, Villa Orlandi, Anacapri, Capri Island, Ital

Cavity control of Excitons in two dimensional Materials

We propose a robust and efficient way of controlling the optical spectra of two-dimensional materials and van der Waals heterostructures by quantum cavity embedding. The cavity light-matter coupling leads to the formation of exciton-polaritons, a superposition of photons and excitons. Our first principles study demonstrates a reordering and mixing of bright and dark excitons spectral features and in the case of a type II van-der-Waals heterostructure an inversion of intra and interlayer excitonic resonances. We further show that the cavity light-matter coupling strongly depends on the dielectric environment and can be controlled by encapsulating the active 2D crystal in another dielectric material. Our theoretical calculations are based on a newly developed non-perturbative many-body framework to solve the coupled electron-photon Schr\"odinger equation in a quantum-electrodynamical extension of the Bethe-Salpeter approach. This approach enables the ab-initio simulations of exciton-polariton states and their dispersion from weak to strong cavity light-matter coupling regimes. Our method is then extended to treat van der Waals heterostructures and encapsulated 2D materials using a simplified Mott-Wannier description of the excitons that can be applied to very large systems beyond reach for fully ab-initio approaches.Comment: 32 pages. 10 figures, 2 tabl

A classification of meteorite impact craters

Systematic classification of meteorite impact craters for lunar and planetary crater

Collabor8: (Re-) Engaging female secondary cohorts in STEM subjects

Demand for skilled professionals in science, technology, engineering and mathematics (STEM) is projected to increase significantly with 75% of the fastest growing occupations requiring STEM skills (Australian Industry Group, 2013). Yet, over the past 20 years, Australia has seen significant decline in the number of secondary students - particularly girls - electing to study science and advanced mathematics (Office of Chief Scientist, 2014). A 2014 national STEM strategy from the Office of the Chief Scientist recommended support for `high levels of participation and success in STEM [education] for all Australians, including women, Indigenous students and students from disadvantaged and marginalised backgrounds’. Recent research builds on previous work (e.g. Fine et al, 2010; Lyons et al, 2012; Sikora, 2012; Mills et al, 2010). Zecharia et al identify three key factors found to be influencing young women’s participation in STEM subjects: 1. Relevance of STEM to sense of identity and future aspirations. 2. Perceived actual and relative ability in STEM subjects. 3. ‘Science capital’ - or experience of STEM, including formal and informal exposure to STEM subjects and careers through the curriculum, schooling, media, culture, family and personal connections’ (Zecharia et al., 2014 p.9). This paper introduces Collabor8, an engineering and IT outreach program for junior female students from high schools serving low socio-economic communities. Collabor8 will test the relative importance of Zecharia et al’s three key factors for participants’ interest in STEM; intention to select STEM subjects in senior high school and tertiary study, and evaluate the chosen outreach model

Improved Answer-Set Programming Encodings for Abstract Argumentation

The design of efficient solutions for abstract argumentation problems is a crucial step towards advanced argumentation systems. One of the most prominent approaches in the literature is to use Answer-Set Programming (ASP) for this endeavor. In this paper, we present new encodings for three prominent argumentation semantics using the concept of conditional literals in disjunctions as provided by the ASP-system clingo. Our new encodings are not only more succinct than previous versions, but also outperform them on standard benchmarks.Comment: To appear in Theory and Practice of Logic Programming (TPLP), Proceedings of ICLP 201

Stream Reasoning in Temporal Datalog

In recent years, there has been an increasing interest in extending traditional stream processing engines with logical, rule-based, reasoning capabilities. This poses significant theoretical and practical challenges since rules can derive new information and propagate it both towards past and future time points; as a result, streamed query answers can depend on data that has not yet been received, as well as on data that arrived far in the past. Stream reasoning algorithms, however, must be able to stream out query answers as soon as possible, and can only keep a limited number of previous input facts in memory. In this paper, we propose novel reasoning problems to deal with these challenges, and study their computational properties on Datalog extended with a temporal sort and the successor function (a core rule-based language for stream reasoning applications)

Spectral Functions of the Uniform Electron Gas via Coupled-Cluster Theory and Comparison to the GWGW and Related Approximations

We use, for the first time, ab initio coupled-cluster theory to compute the spectral function of the uniform electron gas at a Wigner-Seitz radius of $r_\mathrm{s}=4$. The coupled-cluster approximations we employ go significantly beyond the diagrammatic content of state-of-the-art $GW$ theory. We compare our calculations extensively to $GW$ and $GW$-plus-cumulant theory, illustrating the strengths and weaknesses of these methods in capturing the quasiparticle and satellite features of the electron gas. Our accurate calculations further allow us to address the long-standing debate over the occupied bandwidth of metallic sodium. Our findings indicate that the future application of coupled-cluster theory to condensed phase material spectra is highly promising.Comment: 6 pages, 2 figure

Inherent electronic trap states in TiO2 nanocrystals: effect of saturation and sintering

We report a quantum mechanical investigation on the nature of electronic trap states in realistic models of individual and sintered anatase TiO2 nanocrystals (NCs) of ca. 3 nm diameter. We find unoccupied electronic states of lowest energy to be localized within the central part of the NCs, and to originate from under-coordinated surface Ti atoms lying mainly at the edges between the (100) and (101) facets. These localized states are found at about 0.3–0.4 eV below the fully delocalized conduction band states, in good agreement with both electrochemical and spectro-electrochemical results. The overall DensityOf-States (DOS) below the conduction band (CB) can be accurately fitted to an exponential distribution of states, in agreement with capacitance data. Water molecules adsorbed on the NC surface raise the energy and reduce the number of localized states, thus modifying the DOS. As a possible origin of additional trap states, we further investigated the oriented attachment of two TiO2 NCs at various possible interfaces. For the considered models, we found only minor differences between the DOS of two interacting NCs and those of the individual constituent NCs. Our results point at the presence of inherent trap states even in perfectly stoichiometric and crystalline TiO2 NCs due to the unavoidable presence of under-coordinated surface Ti(IV) ions at the (100) facets

Phage displayed peptides/antibodies recognizing growth factors and their tyrosine kinase receptors as tools for anti-cancer therapeutics.

The basic idea of displaying peptides on a phage, introduced by George P. Smith in 1985, was greatly developed and improved by McCafferty and colleagues at the MRC Laboratory of Molecular Biology and, later, by Barbas and colleagues at the Scripps Research Institute. Their approach was dedicated to building a system for the production of antibodies, similar to a naïve B cell repertoire, in order to by-pass the standard hybridoma technology that requires animal immunization. Both groups merged the phage display technology with an antibody library to obtain a huge number of phage variants, each of them carrying a specific antibody ready to bind its target molecule, allowing, later on, rare phage (one in a million) to be isolated by affinity chromatography. Here, we will briefly review the basis of the technology and the therapeutic application of phage-derived bioactive molecules when addressed against key players in tumor development and progression: growth factors and their tyrosine kinase receptors

Time-dependent N-electron valence perturbation theory with matrix product state reference wavefunctions for large active spaces and basis sets: Applications to the chromium dimer and all-trans polyenes

In earlier work [A. Y. Sokolov and G. K.-L. Chan, J. Chem. Phys. 144, 064102 (2016)], we introduced a time-dependent formulation of the second-order N-electron valence perturbation theory (t-NEVPT2) which (i) had a lower computational scaling than the usual internally contracted perturbation formulation and (ii) yielded the fully uncontracted NEVPT2 energy. Here, we present a combination of t-NEVPT2 with a matrix product state (MPS) reference wavefunction (t-MPS-NEVPT2) that allows us to compute uncontracted dynamic correlation energies for large active spaces and basis sets, using the time-dependent density matrix renormalization group algorithm. In addition, we report a low-scaling MPS-based implementation of strongly contracted NEVPT2 (sc-MPS-NEVPT2) that avoids computation of the four-particle reduced density matrix. We use these new methods to compute the dissociation energy of the chromium dimer and to study the low-lying excited states in all-trans polyenes (C_4H_6 to C_(24)H_(26)), incorporating dynamic correlation for reference wavefunctionswith up to 24 active electrons and orbitals