Regular spaceborne measurements revealed that solar brightness varies on all timescales at which it has ever been measured. The state-of-the-art models attribute solar brightens variations to a joint action of surface magnetic field and constantly evolving granulation pattern on the solar surface and reproduce available measurements of solar brightness variability in great detail.
Studies of solar brightness variability have always been of high importance for stellar astronomers, who have been comparing it with the variability of other lower main sequence stars. The interest in solar-stellar comparison has been recently brought to a new level by the unprecedented precision of broadband stellar photometry achieved with the launch of the Kepler and Corot space missions. In general, Sun-like stars show brightness variations similar to those of the Sun but with much wider variety of patterns.
The enormous progress in MHD simulations of solar and stellar atmospheres as well as the development of new computationally-efficient radiative transfer schemes makes it finally possible to extend physics-based solar irradiance models to other stars and connect related solar and stellar studies. We present our recent achievements in modelling stellar brightness variations and show how our modelling can help to answer a very fundamental question of how typical is the Sun as active star.
I will give an overview of the known results about the existence of the weak and strong adiabatic limits in perturbative quantum field theory in the Minkowski space in the Epstein-Glaser framework. One of the characteristic features of this framework is the use of a switching function which plays the role of the infrared regulator. The adiabatic limit provides a method of removing this regulator and defining objects in the physical theory. In particular, the weak adiabatic limit is used to construct the correlation functions, such as the Wightman or Green functions, and the strong adiabatic limit allows to define the scattering operator as well as the interacting fields and their time-ordered products.
The phenomenon known as jamming has historically been studied and promoted in the context of athermal granular matter where loose grains can flow under stress, but compaction or shear strain can lead to a jamming transition into a disordered solid. The jammed state is only a solid in the sense that it can bear a load for a given direction of stress, whereas a change in the direction of stress (e.g. shear reversal) can lead to failure. The mechanism responsible for this rigidity anisotropy is the inter-particle force chains that form in the material . These form with an orientation parallel to the applied stress and bear the load on the system, but obviously cannot sustain stresses orthogonal to the chain. The jamming framework has recently been suggested to extend also to slightly thermal systems  and to dense active matter, including living matter such as in epithelial cell tissues . In this spirit we have studied the effective forces in low temperature thermal amorphous solids, where particles do not mix and flow, but nevertheless move thermally within cages formed by neighboring particles. We have exposed and quantified the many-body nature of these effective forces [4, 5] that are responsible for the load bearing effective force chains. This finding also bears implications for the applicability of the hard-sphere theory of jamming  to realistic systems and contradicts a recent claim that the mechanism of jamming in soft matter is dimensionally independent 
In this Task Force Meeting, we summarize our recent progress regarding the quest of new topological states of matter and we discuss interaction effects. We address specific models and geometries related to Josephson physics and fractional quantum Hall phases in ladder systems, the Haldane model and the Kane-Mele model in two dimensions both for fermion and boson systems. We also address new hybrid geometries and proximity effects, as well as the Mott limit in relation with quantum spin liquids and Z2 models with Majorana fermions. We present new probes and protocols to realize and characterize these quantum states as well as the transport at the edges.
The experimental realization of the Harper-Hofstadter model of hard-core bosons in ultra-cold atomic gases has placed fractional states of matter within reach. These experiments naturally probe the dynamics of the fractional state, yet little is known about such properties or how they may differ compared to their noninteracting counterparts. We use density-matrix renormalization group simulations to explore both ground state and dynamical properties of the fractional Chern insulator (FCI) state in the Harper-Hofstadter model.
Ordinary materials are "passive" in the sense that their constituents are typically made by inert particles which are subjected to thermal fluctuations, internal interactions and external fields but do not move on their own. Living systems, like schools of fish, swarms of birds, pedestrians and swimming microbes are called "active matter" since they are composed of self-propelled constituents. Active matter
is intrinsically in nonequilibrium and exhibits a plethora of novel
phenomena as revealed by a recent combined effort of statistical theory, computer simulation and real-space experiments.
The colloquium talk provides an introduction into the physics of active matter focussing on artificial microswimmers as a key example of active soft matter . A number of single-particle and collective
phenomena in active matter will be adressed ranging from circle swimming to motility-induced phase separation and inertial delay
The utilization of fuels generated from renewable sources (Renewable Fuels, RFs) is a target that our society has to achieve in a relatively short period of time, owing to the rapid depletion of fossil fuels reserves and to the dramatic environmental consequences of their massive exploitation. Catalysis has a key role in RFs generation since it allows the energetic costs of the processes, which must be provided by renewable sources (sun and wind), to be minimized –ideally – down to those imposed by thermodynamics.
Ir-based molecules and materials are among the most active catalysts in both oxidative and reductive catalytic processes underlying the generation of RFs. Unfortunately, they suffer from the little abundance of iridium in the Earth crust. Consequently, parallel to the search for efficient non-noble metal catalysts, many efforts are directed forward iridium (and, in general, noble-metal) atom economy. Three strategies have been proposed to minimizing the atomic contents of noble metal: 1) exploiting molecular catalysts, under the assumption that all metal centres are catalytically active; 2) anchoring a well-defined molecular catalyst onto a suitable support, thus obtaining a heterogenized catalyst, combining the positive aspects of homogeneous and heterogeneous catalysis; 3) diluting active metal centres in a suitable material with features that maximize the metal-accessibility and performances.
In this lecture, the results of our efforts aimed at pursuing all three strategies for developing efficient iridium catalysts for water oxidation,HCOOH dehydrogenation,and NAD+/NADH transformations are illustrated.
Life on a planet like Earth has its roots in processes starting with the formation of interstellar clouds and first complex molecules. What
follows is a sequence of events that are decisive for the success of
eventual life formation: the collapse of clouds to protostars in a cluster environment, the onset of "chemical factories" inside protostellar disks, the formation of a planetary system that remains dynamically stable with the right type of planet in the habitable zone, the transport of sufficient amounts of water to such a planet, the generation of a solid surface and an habitable atmosphere, a clement interaction with the young host star, the favorable formation of biomolecules on the planetary surface and eventually the steps to metabolism and reproduction of initial life forms. Many of these steps are still poorly understood and some of them appear unlikely, but recent research in this widely interdisciplinary field has provided
surprising insights into the complex astrophysical conditions for life. I present research highlights from a tale of several 100 million years of cosmic evolution from the interstellar medium to first life forms on a planet, emphasizing the sequence of critical events that must all succeed for life to emerge.
The identification of homogeneous catalysts for the fixation of dinitrogen has been a long-standing target in inorganic chemistry. While it is unclear whether homogeneous catalysts that produce ammonia from N2 will ever become economically competitive with the Haber-Bosch process, such catalysts will open up new synthetic routes for the incorporation of N-atoms derived from dinitrogen into industrially relevant chemicals that are not sourced from fossil resources.
A less well explored alternative to thermal nitrogen fixation with homogeneous catalysts is the photochemical cleavage of dinitrogen, which has been demonstrated with several synthetic catalysts featuring linear metal-nitrogen-nitrogen-metal cores. The photocleavage of dinitrogen is a particularly attractive as light energy is used to cleave the strong dinitrogen bond and stored in the metal-nitrogen bonds that are formed during this process. In some cases, the splitting of the nitrogen-nitrogen bond upon irradiation with light from the solar spectrum competes with the scission of the metal-nitrogen bond. However, the precise photochemical and photophysical processes that induce either process are poorly understood, hampering the systematic improvement of these catalysts.
A quantum chemical analysis of the electronic structures of dinitrogen photocleavage catalysts and the bond cleavage processes will help in designing improved catalysts. We present our current understanding of dinitrogen photocleavage, evaluate similarities and differences between known catalysts and discuss implications for possible pathways towards the improvement of their efficiencies.
Realizing new quantum states in solid state materials is of fundamental interest. Due to recent developments in experimental techniques, Floquet engineering, i.e. control of quantum states by time periodical external fields, is becoming a practical way to search for exotic nonequilibrium quantum states. In this talk, I will try to present the overview of this field based on our recent results.
Control of topology by circularly polarized laser (CPL): By applying CPL to materials such as 2D, 3D Dirac semimetals and Mott insulators, one can transform them into Floquet Chern insulator, Floquet Weyl semimetal, and even induce scalar chirality.
Dielectric breakdown of Mott insulators: Nonequilibrium steady state stabilized with current in Mott insulators was discovered to show interesting quantum features.
Integer quantum Hall heterodyne: Electrons in oscillating magnetic fields realize a dissipationless frequency converter (heterodyne) which may be used in future communication devices.
Oxygen electrocatalysis plays a pivotal role in the development of energy storage and conversion devices, such as metal–air batteries, fuel cells, and electrolyzers. Transition metal oxides (including Manganites) are being investigated as cost-effective alternatives to catalysts containing Pt, Ru, or Ir, however progress is hampered by the sluggish kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER).
Investigation of model epitaxial oxide thin films shed light on the reaction mechanism and what material properties govern the kinetics. By quantifying the formation of hydroxyls in an aqueous environment using ambient pressure X-ray photoelectron spectroscopy, we identify the electronic structure origin of the affinity for this reaction intermediate in oxygen electrocatalysis. The strength of interaction with hydroxyls correlates inversely with activity for the reduction reaction, illustrating detrimental effects of strong water interactions at the electrocatalyst surface. The understanding obtained from epitaxial surfaces develops molecular insight regarding interactions at oxide/water interfaces and mechanisms of oxygen electrocatalysis, guiding the rational design of high-surface-area oxide catalysts for technical application.
The Deep Underground Neutrino Experiment (DUNE) will be an international observatory for neutrino science, designed, constructed and operated by a global collaboration of scientists. Primary science drivers are the discovery of CP violation in the neutrino sector, the detection of neutrinos from supernovae, and the search for baryon number violation. DUNE will consist of two neutrino detectors placed in the world’s most intense neutrino beam. A near detector will record particle interactions near the source of the beam at Fermilab close to Chicago. A second, much larger, far detector operating with more than 40 kt of liquid-argon will be installed a mile underground in South Dakota. Several mid-size liquid-argon detectors at Fermilab and CERN are being constructed to demonstrate the potential of the cutting-edge liquid-argon technology employed for DUNE. I will introduce the technology and give an overview of the current status, including first ProtoDUNE results, and discuss the future discovery potential of the DUNE programme.
Eclipsing Time Variations (ETVs) are observed in several types of
close binaries, and in some of them their nature is still uncertain.
Post-common-envelope binaries (PCEBs) are of particular interest in this context, as ~90% of them present ETVs on their O-C diagram of the eclipsing times. The planetary hypothesis attributes these variations to the presence of a third (and sometimes fourth) companion, but in some cases this solution has unstable orbits over short periods of time and searches for a third companion have failed. Another explanation links the ETVs to changes in the gravitational quadrupole moment of the magnetically active component of the binary during its magnetic cycle, thus changing the gravitational potential.
This is known as the Applegate mechanism. In this talk I will focus on this mechanism and our current efforts to link the ETVs to magnetic activity in PCEBs, particularly on theoretical and computational grounds.