@article{14003, abstract = {Molecular chirality plays an essential role in most biochemical processes. The observation and quantification of chirality-sensitive signals, however, remains extremely challenging, especially on ultrafast timescales and in dilute media. Here, we describe the experimental realization of an all-optical and ultrafast scheme for detecting chiral dynamics in molecules. This technique is based on high-harmonic generation by a combination of two-color counterrotating femtosecond laser pulses with polarization states tunable from linear to circular. We demonstrate two different implementations of chiral-sensitive high-harmonic spectroscopy on an ensemble of randomly oriented methyloxirane molecules in the gas phase. Using two elliptically polarized fields, we observe that the ellipticities maximizing the harmonic signal reach up to 4.4 ± 0.2 % (at 17.6 eV). Using two circularly polarized fields, we observe circular dichroisms ranging up to 13 ± 6 % (28.3–33.1 eV). Our theoretical analysis confirms that the observed chiral response originates from subfemtosecond electron dynamics driven by the magnetic component of the driving laser field. This assignment is supported by the experimental observation of a strong intensity dependence of the chiral effects and its agreement with theory. We moreover report and explain a pronounced variation of the signal strength and dichroism with the driving-field ellipticities and harmonic orders. Finally, we demonstrate the sensitivity of the experimental observables to the shape of the electron hole. This technique for chiral discrimination will yield femtosecond temporal resolution when integrated in a pump-probe scheme and subfemtosecond resolution on chiral charge migration in a self-probing scheme.}, author = {Baykusheva, Denitsa Rangelova and Wörner, Hans Jakob}, issn = {2160-3308}, journal = {Physical Review X}, keywords = {General Physics and Astronomy}, number = {3}, publisher = {American Physical Society}, title = {{Chiral discrimination through bielliptical high-harmonic spectroscopy}}, doi = {10.1103/physrevx.8.031060}, volume = {8}, year = {2018}, } @article{14284, abstract = {Pore-forming toxins (PFT) are virulence factors that transform from soluble to membrane-bound states. The Yersinia YaxAB system represents a family of binary α-PFTs with orthologues in human, insect, and plant pathogens, with unknown structures. YaxAB was shown to be cytotoxic and likely involved in pathogenesis, though the molecular basis for its two-component lytic mechanism remains elusive. Here, we present crystal structures of YaxA and YaxB, together with a cryo-electron microscopy map of the YaxAB complex. Our structures reveal a pore predominantly composed of decamers of YaxA–YaxB heterodimers. Both subunits bear membrane-active moieties, but only YaxA is capable of binding to membranes by itself. YaxB can subsequently be recruited to membrane-associated YaxA and induced to present its lytic transmembrane helices. Pore formation can progress by further oligomerization of YaxA–YaxB dimers. Our results allow for a comparison between pore assemblies belonging to the wider ClyA-like family of α-PFTs, highlighting diverse pore architectures.}, author = {Bräuning, Bastian and Bertosin, Eva and Praetorius, Florian M and Ihling, Christian and Schatt, Alexandra and Adler, Agnes and Richter, Klaus and Sinz, Andrea and Dietz, Hendrik and Groll, Michael}, issn = {2041-1723}, journal = {Nature Communications}, keywords = {General Physics and Astronomy, General Biochemistry, Genetics and Molecular Biology, General Chemistry, Multidisciplinary}, publisher = {Springer Nature}, title = {{Structure and mechanism of the two-component α-helical pore-forming toxin YaxAB}}, doi = {10.1038/s41467-018-04139-2}, volume = {9}, year = {2018}, } @article{10362, abstract = {Nuclear pore complexes (NPCs) form gateways that control molecular exchange between the nucleus and the cytoplasm. They impose a diffusion barrier to macromolecules and enable the selective transport of nuclear transport receptors with bound cargo. The underlying mechanisms that establish these permeability properties remain to be fully elucidated but require unstructured nuclear pore proteins rich in Phe-Gly (FG)-repeat domains of different types, such as FxFG and GLFG. While physical modeling and in vitro approaches have provided a framework for explaining how the FG network contributes to the barrier and transport properties of the NPC, it remains unknown whether the number and/or the spatial positioning of different FG-domains along a cylindrical, ∼40 nm diameter transport channel contributes to their collective properties and function. To begin to answer these questions, we have used DNA origami to build a cylinder that mimics the dimensions of the central transport channel and can house a specified number of FG-domains at specific positions with easily tunable design parameters, such as grafting density and topology. We find the overall morphology of the FG-domain assemblies to be dependent on their chemical composition, determined by the type and density of FG-repeat, and on their architectural confinement provided by the DNA cylinder, largely consistent with here presented molecular dynamics simulations based on a coarse-grained polymer model. In addition, high-speed atomic force microscopy reveals local and reversible FG-domain condensation that transiently occludes the lumen of the DNA central channel mimics, suggestive of how the NPC might establish its permeability properties.}, author = {Fisher, Patrick D. Ellis and Shen, Qi and Akpinar, Bernice and Davis, Luke K. and Chung, Kenny Kwok Hin and Baddeley, David and Šarić, Anđela and Melia, Thomas J. and Hoogenboom, Bart W. and Lin, Chenxiang and Lusk, C. Patrick}, issn = {1936-086X}, journal = {ACS Nano}, keywords = {general physics and astronomy}, number = {2}, pages = {1508--1518}, publisher = {American Chemical Society}, title = {{A Programmable DNA origami platform for organizing intrinsically disordered nucleoporins within nanopore confinement}}, doi = {10.1021/acsnano.7b08044}, volume = {12}, year = {2018}, } @article{10626, abstract = {Owing to their wide tunability, multiple internal degrees of freedom, and low disorder, graphene heterostructures are emerging as a promising experimental platform for fractional quantum Hall (FQH) studies. Here, we report FQH thermal activation gap measurements in dual graphite-gated monolayer graphene devices fabricated in an edgeless Corbino geometry. In devices with substrate-induced sublattice splitting, we find a tunable crossover between single- and multicomponent FQH states in the zero energy Landau level. Activation gaps in the single-component regime show excellent agreement with numerical calculations using a single broadening parameter Γ≈7.2K. In the first excited Landau level, in contrast, FQH gaps are strongly influenced by Landau level mixing, and we observe an unexpected valley-ordered state at integer filling ν=−4.}, author = {Polshyn, Hryhoriy and Zhou, H. and Spanton, E. M. and Taniguchi, T. and Watanabe, K. and Young, A. F.}, issn = {1079-7114}, journal = {Physical Review Letters}, keywords = {general physics and astronomy}, number = {22}, publisher = {American Physical Society}, title = {{Quantitative transport measurements of fractional quantum Hall energy gaps in edgeless graphene devices}}, doi = {10.1103/physrevlett.121.226801}, volume = {121}, year = {2018}, } @article{11065, abstract = {Premature aging disorders provide an opportunity to study the mechanisms that drive aging. In Hutchinson-Gilford progeria syndrome (HGPS), a mutant form of the nuclear scaffold protein lamin A distorts nuclei and sequesters nuclear proteins. We sought to investigate protein homeostasis in this disease. Here, we report a widespread increase in protein turnover in HGPS-derived cells compared to normal cells. We determine that global protein synthesis is elevated as a consequence of activated nucleoli and enhanced ribosome biogenesis in HGPS-derived fibroblasts. Depleting normal lamin A or inducing mutant lamin A expression are each sufficient to drive nucleolar expansion. We further show that nucleolar size correlates with donor age in primary fibroblasts derived from healthy individuals and that ribosomal RNA production increases with age, indicating that nucleolar size and activity can serve as aging biomarkers. While limiting ribosome biogenesis extends lifespan in several systems, we show that increased ribosome biogenesis and activity are a hallmark of premature aging.}, author = {Buchwalter, Abigail and HETZER, Martin W}, issn = {2041-1723}, journal = {Nature Communications}, keywords = {General Physics and Astronomy, General Biochemistry, Genetics and Molecular Biology, General Chemistry}, publisher = {Springer Nature}, title = {{Nucleolar expansion and elevated protein translation in premature aging}}, doi = {10.1038/s41467-017-00322-z}, volume = {8}, year = {2017}, } @article{14004, abstract = {High-harmonic spectroscopy driven by circularly polarized laser pulses and their counterrotating second harmonic is a new branch of attosecond science which currently lacks quantitative interpretations. We extend this technique to the midinfrared regime and record detailed high-harmonic spectra of several rare-gas atoms. These results are compared with the solution of the Schrödinger equation in three dimensions and calculations based on the strong-field approximation that incorporate accurate scattering-wave recombination matrix elements. A quantum-orbit analysis of these results provides a transparent interpretation of the measured intensity ratios of symmetry-allowed neighboring harmonics in terms of (i) a set of propensity rules related to the angular momentum of the atomic orbitals, (ii) atom-specific matrix elements related to their electronic structure, and (iii) the interference of the emissions associated with electrons in orbitals corotating or counterrotating with the laser fields. These results provide the foundation for a quantitative understanding of bicircular high-harmonic spectroscopy.}, author = {Baykusheva, Denitsa Rangelova and Brennecke, Simon and Lein, Manfred and Wörner, Hans Jakob}, issn = {1079-7114}, journal = {Physical Review Letters}, keywords = {General Physics and Astronomy}, number = {20}, publisher = {American Physical Society}, title = {{Signatures of electronic structure in bicircular high-harmonic spectroscopy}}, doi = {10.1103/physrevlett.119.203201}, volume = {119}, year = {2017}, } @article{14005, abstract = {Strong-field photoelectron holography and laser-induced electron diffraction (LIED) are two powerful emerging methods for probing the ultrafast dynamics of molecules. However, both of them have remained restricted to static systems and to nuclear dynamics induced by strong-field ionization. Here we extend these promising methods to image purely electronic valence-shell dynamics in molecules using photoelectron holography. In the same experiment, we use LIED and photoelectron holography simultaneously, to observe coupled electronic-rotational dynamics taking place on similar timescales. These results offer perspectives for imaging ultrafast dynamics of molecules on femtosecond to attosecond timescales.}, author = {Walt, Samuel G. and Bhargava Ram, Niraghatam and Atala, Marcos and Shvetsov-Shilovski, Nikolay I and von Conta, Aaron and Baykusheva, Denitsa Rangelova and Lein, Manfred and Wörner, Hans Jakob}, issn = {2041-1723}, journal = {Nature Communications}, keywords = {General Physics and Astronomy, General Biochemistry, Genetics and Molecular Biology, General Chemistry, Multidisciplinary}, publisher = {Springer Nature}, title = {{Dynamics of valence-shell electrons and nuclei probed by strong-field holography and rescattering}}, doi = {10.1038/ncomms15651}, volume = {8}, year = {2017}, } @article{14006, abstract = {We present a theoretical formalism for the calculation of attosecond delays in molecular photoionization. It is shown how delays relevant to one-photon-ionization, also known as Eisenbud-Wigner-Smith delays, can be obtained from the complex dipole matrix elements provided by molecular quantum scattering theory. These results are used to derive formulae for the delays measured by two-photon attosecond interferometry based on an attosecond pulse train and a dressing femtosecond infrared pulse. These effective delays are first expressed in the molecular frame where maximal information about the molecular photoionization dynamics is available. The effects of averaging over the emission direction of the electron and the molecular orientation are introduced analytically. We illustrate this general formalism for the case of two polyatomic molecules. N2O serves as an example of a polar linear molecule characterized by complex photoionization dynamics resulting from the presence of molecular shape resonances. H2O illustrates the case of a non-linear molecule with comparably simple photoionization dynamics resulting from a flat continuum. Our theory establishes the foundation for interpreting measurements of the photoionization dynamics of all molecules by attosecond metrology.}, author = {Baykusheva, Denitsa Rangelova and Wörner, Hans Jakob}, issn = {1089-7690}, journal = {The Journal of Chemical Physics}, keywords = {Physical and Theoretical Chemistry, General Physics and Astronomy}, number = {12}, publisher = {AIP Publishing}, title = {{Theory of attosecond delays in molecular photoionization}}, doi = {10.1063/1.4977933}, volume = {146}, year = {2017}, } @article{14031, abstract = {High-harmonic spectroscopy driven by circularly polarized laser pulses and their counterrotating second harmonic is a new branch of attosecond science which currently lacks quantitative interpretations. We extend this technique to the midinfrared regime and record detailed high-harmonic spectra of several rare-gas atoms. These results are compared with the solution of the Schrödinger equation in three dimensions and calculations based on the strong-field approximation that incorporate accurate scattering-wave recombination matrix elements. A quantum-orbit analysis of these results provides a transparent interpretation of the measured intensity ratios of symmetry-allowed neighboring harmonics in terms of (i) a set of propensity rules related to the angular momentum of the atomic orbitals, (ii) atom-specific matrix elements related to their electronic structure, and (iii) the interference of the emissions associated with electrons in orbitals corotating or counterrotating with the laser fields. These results provide the foundation for a quantitative understanding of bicircular high-harmonic spectroscopy.}, author = {Baykusheva, Denitsa Rangelova and Brennecke, Simon and Lein, Manfred and Wörner, Hans Jakob}, issn = {1079-7114}, journal = {Physical Review Letters}, keywords = {General Physics and Astronomy}, number = {20}, publisher = {American Physical Society}, title = {{Signatures of electronic structure in bicircular high-harmonic spectroscopy}}, doi = {10.1103/physrevlett.119.203201}, volume = {119}, year = {2017}, } @article{11072, abstract = {Spatiotemporal activation of RhoA and actomyosin contraction underpins cellular adhesion and division. Loss of cell–cell adhesion and chromosomal instability are cardinal events that drive tumour progression. Here, we show that p120-catenin (p120) not only controls cell–cell adhesion, but also acts as a critical regulator of cytokinesis. We find that p120 regulates actomyosin contractility through concomitant binding to RhoA and the centralspindlin component MKLP1, independent of cadherin association. In anaphase, p120 is enriched at the cleavage furrow where it binds MKLP1 to spatially control RhoA GTPase cycling. Binding of p120 to MKLP1 during cytokinesis depends on the N-terminal coiled-coil domain of p120 isoform 1A. Importantly, clinical data show that loss of p120 expression is a common event in breast cancer that strongly correlates with multinucleation and adverse patient survival. In summary, our study identifies p120 loss as a driver event of chromosomal instability in cancer. }, author = {van de Ven, Robert A.H. and de Groot, Jolien S. and Park, Danielle and van Domselaar, Robert and de Jong, Danielle and Szuhai, Karoly and van der Wall, Elsken and Rueda, Oscar M. and Ali, H. Raza and Caldas, Carlos and van Diest, Paul J. and HETZER, Martin W and Sahai, Erik and Derksen, Patrick W.B.}, issn = {2041-1723}, journal = {Nature Communications}, keywords = {General Physics and Astronomy, General Biochemistry, Genetics and Molecular Biology, General Chemistry}, publisher = {Springer Nature}, title = {{p120-catenin prevents multinucleation through control of MKLP1-dependent RhoA activity during cytokinesis}}, doi = {10.1038/ncomms13874}, volume = {7}, year = {2016}, } @article{14010, abstract = {We report measurements of energy-dependent attosecond photoionization delays between the two outer-most valence shells of N2O and H2O. The combination of single-shot signal referencing with the use of different metal foils to filter the attosecond pulse train enables us to extract delays from congested spectra. Remarkably large delays up to 160 as are observed in N2O, whereas the delays in H2O are all smaller than 50 as in the photon-energy range of 20-40 eV. These results are interpreted by developing a theory of molecular photoionization delays. The long delays measured in N2O are shown to reflect the population of molecular shape resonances that trap the photoelectron for a duration of up to ∼110 as. The unstructured continua of H2O result in much smaller delays at the same photon energies. Our experimental and theoretical methods make the study of molecular attosecond photoionization dynamics accessible.}, author = {Huppert, Martin and Jordan, Inga and Baykusheva, Denitsa Rangelova and von Conta, Aaron and Wörner, Hans Jakob}, issn = {1079-7114}, journal = {Physical Review Letters}, keywords = {General Physics and Astronomy}, number = {9}, publisher = {American Physical Society}, title = {{Attosecond delays in molecular photoionization}}, doi = {10.1103/physrevlett.117.093001}, volume = {117}, year = {2016}, } @article{14011, abstract = {We introduce bicircular high-harmonic spectroscopy as a new method to probe dynamical symmetries of atoms and molecules and their evolution in time. Our approach is based on combining a circularly polarized femtosecond fundamental field of frequency ω with its counterrotating second harmonic 2ω. We demonstrate the ability of bicircular high-harmonic spectroscopy to characterize the orbital angular momentum symmetry of atomic orbitals. We further show that breaking the threefold rotational symmetry of the generating medium-at the level of either the ensemble or that of a single molecule-results in the emission of the otherwise parity-forbidden frequencies 3qω  (q∈N), which provide a background-free probe of dynamical molecular symmetries.}, author = {Baykusheva, Denitsa Rangelova and Ahsan, Md Sabbir and Lin, Nan and Wörner, Hans Jakob}, issn = {1079-7114}, journal = {Physical Review Letters}, keywords = {General Physics and Astronomy}, number = {12}, publisher = {American Physical Society}, title = {{Bicircular high-harmonic spectroscopy reveals dynamical symmetries of atoms and molecules}}, doi = {10.1103/physrevlett.116.123001}, volume = {116}, year = {2016}, } @article{10376, abstract = {Nucleation processes are at the heart of a large number of phenomena, from cloud formation to protein crystallization. A recently emerging area where nucleation is highly relevant is the initiation of filamentous protein self-assembly, a process that has broad implications in many research areas ranging from medicine to nanotechnology. As such, spontaneous nucleation of protein fibrils has received much attention in recent years with many theoretical and experimental studies focusing on the underlying physical principles. In this paper we make a step forward in this direction and explore the early time behaviour of filamentous protein growth in the context of nucleation theory. We first provide an overview of the thermodynamics and kinetics of spontaneous nucleation of protein filaments in the presence of one relevant degree of freedom, namely the cluster size. In this case, we review how key kinetic observables, such as the reaction order of spontaneous nucleation, are directly related to the physical size of the critical nucleus. We then focus on the increasingly prominent case of filament nucleation that includes a conformational conversion of the nucleating building-block as an additional slow step in the nucleation process. Using computer simulations, we study the concentration dependence of the nucleation rate. We find that, under these circumstances, the reaction order of spontaneous nucleation with respect to the free monomer does no longer relate to the overall physical size of the nucleating aggregate but rather to the portion of the aggregate that actively participates in the conformational conversion. Our results thus provide a novel interpretation of the common kinetic descriptors of protein filament formation, including the reaction order of the nucleation step or the scaling exponent of lag times, and put into perspective current theoretical descriptions of protein aggregation.}, author = {Šarić, Anđela and Michaels, Thomas C. T. and Zaccone, Alessio and Knowles, Tuomas P. J. and Frenkel, Daan}, issn = {1089-7690}, journal = {The Journal of Chemical Physics}, keywords = {physical and theoretical chemistry, general physics and astronomy}, number = {21}, publisher = {American Institute of Physics}, title = {{Kinetics of spontaneous filament nucleation via oligomers: Insights from theory and simulation}}, doi = {10.1063/1.4965040}, volume = {145}, year = {2016}, } @article{10378, abstract = {The ability of biological molecules to replicate themselves is the foundation of life, requiring a complex cellular machinery. However, a range of aberrant processes involve the self-replication of pathological protein structures without any additional assistance. One example is the autocatalytic generation of pathological protein aggregates, including amyloid fibrils, involved in neurodegenerative disorders. Here, we use computer simulations to identify the necessary requirements for the self-replication of fibrillar assemblies of proteins. We establish that a key physical determinant for this process is the affinity of proteins for the surfaces of fibrils. We find that self-replication can take place only in a very narrow regime of inter-protein interactions, implying a high level of sensitivity to system parameters and experimental conditions. We then compare our theoretical predictions with kinetic and biosensor measurements of fibrils formed from the Aβ peptide associated with Alzheimer’s disease. Our results show a quantitative connection between the kinetics of self-replication and the surface coverage of fibrils by monomeric proteins. These findings reveal the fundamental physical requirements for the formation of supra-molecular structures able to replicate themselves, and shed light on mechanisms in play in the proliferation of protein aggregates in nature.}, author = {Šarić, Anđela and Buell, Alexander K. and Meisl, Georg and Michaels, Thomas C. T. and Dobson, Christopher M. and Linse, Sara and Knowles, Tuomas P. J. and Frenkel, Daan}, issn = {1745-2481}, journal = {Nature Physics}, keywords = {general physics and astronomy}, number = {9}, pages = {874--880}, publisher = {Springer Nature}, title = {{Physical determinants of the self-replication of protein fibrils}}, doi = {10.1038/nphys3828}, volume = {12}, year = {2016}, } @article{10380, abstract = {Using non-equilibrium molecular dynamics simulations, it has been recently demonstrated that water molecules align in response to an imposed temperature gradient, resulting in an effective electric field. Here, we investigate how thermally induced fields depend on the underlying treatment of long-ranged interactions. For the short-ranged Wolf method and Ewald summation, we find the peak strength of the field to range between 2 × 107 and 5 × 107 V/m for a temperature gradient of 5.2 K/Å. Our value for the Wolf method is therefore an order of magnitude lower than the literature value [J. A. Armstrong and F. Bresme, J. Chem. Phys. 139, 014504 (2013); J. Armstrong et al., J. Chem. Phys. 143, 036101 (2015)]. We show that this discrepancy can be traced back to the use of an incorrect kernel in the calculation of the electrostatic field. More seriously, we find that the Wolf method fails to predict correct molecular orientations, resulting in dipole densities with opposite sign to those computed using Ewald summation. By considering two different multipole expansions, we show that, for inhomogeneous polarisations, the quadrupole contribution can be significant and even outweigh the dipole contribution to the field. Finally, we propose a more accurate way of calculating the electrostatic potential and the field. In particular, we show that averaging the microscopic field analytically to obtain the macroscopic Maxwell field reduces the error bars by up to an order of magnitude. As a consequence, the simulation times required to reach a given statistical accuracy decrease by up to two orders of magnitude.}, author = {Wirnsberger, P. and Fijan, D. and Šarić, Anđela and Neumann, M. and Dellago, C. and Frenkel, D.}, issn = {1089-7690}, journal = {The Journal of Chemical Physics}, keywords = {physical and theoretical chemistry, general physics and astronomy}, number = {22}, publisher = {American Institute of Physics}, title = {{Non-equilibrium simulations of thermally induced electric fields in water}}, doi = {10.1063/1.4953036}, volume = {144}, year = {2016}, } @article{8456, abstract = {The large majority of three-dimensional structures of biological macromolecules have been determined by X-ray diffraction of crystalline samples. High-resolution structure determination crucially depends on the homogeneity of the protein crystal. Overall ‘rocking’ motion of molecules in the crystal is expected to influence diffraction quality, and such motion may therefore affect the process of solving crystal structures. Yet, so far overall molecular motion has not directly been observed in protein crystals, and the timescale of such dynamics remains unclear. Here we use solid-state NMR, X-ray diffraction methods and μs-long molecular dynamics simulations to directly characterize the rigid-body motion of a protein in different crystal forms. For ubiquitin crystals investigated in this study we determine the range of possible correlation times of rocking motion, 0.1–100 μs. The amplitude of rocking varies from one crystal form to another and is correlated with the resolution obtainable in X-ray diffraction experiments.}, author = {Ma, Peixiang and Xue, Yi and Coquelle, Nicolas and Haller, Jens D. and Yuwen, Tairan and Ayala, Isabel and Mikhailovskii, Oleg and Willbold, Dieter and Colletier, Jacques-Philippe and Skrynnikov, Nikolai R. and Schanda, Paul}, issn = {2041-1723}, journal = {Nature Communications}, keywords = {General Biochemistry, Genetics and Molecular Biology, General Physics and Astronomy, General Chemistry}, publisher = {Springer Nature}, title = {{Observing the overall rocking motion of a protein in a crystal}}, doi = {10.1038/ncomms9361}, volume = {6}, year = {2015}, } @article{8498, abstract = {In the present note we announce a proof of a strong form of Arnold diffusion for smooth convex Hamiltonian systems. Let ${\mathbb T}^2$ be a 2-dimensional torus and B2 be the unit ball around the origin in ${\mathbb R}^2$ . Fix ρ > 0. Our main result says that for a 'generic' time-periodic perturbation of an integrable system of two degrees of freedom $H_0(p)+\varepsilon H_1(\theta,p,t),\quad \ \theta\in {\mathbb T}^2,\ p\in B^2,\ t\in {\mathbb T}={\mathbb R}/{\mathbb Z}$ , with a strictly convex H0, there exists a ρ-dense orbit (θε, pε, t)(t) in ${\mathbb T}^2 \times B^2 \times {\mathbb T}$ , namely, a ρ-neighborhood of the orbit contains ${\mathbb T}^2 \times B^2 \times {\mathbb T}$ . Our proof is a combination of geometric and variational methods. The fundamental elements of the construction are the usage of crumpled normally hyperbolic invariant cylinders from [9], flower and simple normally hyperbolic invariant manifolds from [36] as well as their kissing property at a strong double resonance. This allows us to build a 'connected' net of three-dimensional normally hyperbolic invariant manifolds. To construct diffusing orbits along this net we employ a version of the Mather variational method [41] equipped with weak KAM theory [28], proposed by Bernard in [7].}, author = {Kaloshin, Vadim and Zhang, K}, issn = {0951-7715}, journal = {Nonlinearity}, keywords = {Mathematical Physics, General Physics and Astronomy, Applied Mathematics, Statistical and Nonlinear Physics}, number = {8}, pages = {2699--2720}, publisher = {IOP Publishing}, title = {{Arnold diffusion for smooth convex systems of two and a half degrees of freedom}}, doi = {10.1088/0951-7715/28/8/2699}, volume = {28}, year = {2015}, } @article{14014, abstract = {We have studied a coupled electronic-nuclear wave packet in nitric oxide using time-resolved strong-field photoelectron holography and rescattering. We show that the electronic dynamics mainly appears in the holographic structures whereas nuclear motion strongly modulates the angular distribution of the rescattered photoelectrons.}, author = {Walt, Samuel G and Ram, N Bhargava and von Conta, Aaron and Baykusheva, Denitsa Rangelova and Atala, Marcos and Wörner, Hans Jakob}, issn = {1742-6596}, journal = {Journal of Physics: Conference Series}, keywords = {General Physics and Astronomy}, number = {11}, publisher = {IOP Publishing}, title = {{Resolving the dynamics of valence-shell electrons and nuclei through laser-induced diffraction and holography}}, doi = {10.1088/1742-6596/635/11/112135}, volume = {635}, year = {2015}, } @article{14015, abstract = {We advance high-harmonic spectroscopy to resolve molecular charge migration in time and space and simultaneously demonstrate extensive control over the process. A multidimensional approach enables us to reconstruct both quantum amplitudes and phases with a resolution of better than 100 attoseconds and to separately reconstruct field-free and laser- driven charge migration. Our techniques make charge migration in molecules measurable on the attosecond time scale and open new avenues for laser control of electronic primary processes.}, author = {Kraus, P M and Mignolet, B and Baykusheva, Denitsa Rangelova and Rupenyan, A and Horný, L and Penka, E F and Tolstikhin, O I and Schneider, J and Jensen, F and Madsen, L B and Bandrauk, A D and Remacle, F and Wörner, H J}, issn = {1742-6596}, journal = {Journal of Physics: Conference Series}, keywords = {General Physics and Astronomy}, number = {11}, publisher = {IOP Publishing}, title = {{Attosecond charge migration and its laser control}}, doi = {10.1088/1742-6596/635/11/112136}, volume = {635}, year = {2015}, } @article{14016, abstract = {All attosecond time-resolved measurements have so far relied on the use of intense near-infrared laser pulses. In particular, attosecond streaking, laser-induced electron diffraction and high-harmonic generation all make use of non-perturbative light–matter interactions. Remarkably, the effect of the strong laser field on the studied sample has often been neglected in previous studies. Here we use high-harmonic spectroscopy to measure laser-induced modifications of the electronic structure of molecules. We study high-harmonic spectra of spatially oriented CH3F and CH3Br as generic examples of polar polyatomic molecules. We accurately measure intensity ratios of even and odd-harmonic orders, and of the emission from aligned and unaligned molecules. We show that these robust observables reveal a substantial modification of the molecular electronic structure by the external laser field. Our insights offer new challenges and opportunities for a range of emerging strong-field attosecond spectroscopies.}, author = {Kraus, P. M. and Tolstikhin, O. I. and Baykusheva, Denitsa Rangelova and Rupenyan, A. and Schneider, J. and Bisgaard, C. Z. and Morishita, T. and Jensen, F. and Madsen, L. B. and Wörner, H. J.}, issn = {2041-1723}, journal = {Nature Communications}, keywords = {General Physics and Astronomy, General Biochemistry, Genetics and Molecular Biology, General Chemistry, Multidisciplinary}, publisher = {Springer Nature}, title = {{Observation of laser-induced electronic structure in oriented polyatomic molecules}}, doi = {10.1038/ncomms8039}, volume = {6}, year = {2015}, }