Coexisting patterns of population oscillations: the degenerate Neimark Sacker bifurcation as a generic mechanism

We investigate a population dynamics model that exhibits a Neimark Sacker bifurcation with a period that is naturally close to 4. Beyond the bifurcation, the period becomes soon locked at 4 due to a strong resonance, and a second attractor of period 2 emerges, which coexists with the first attractor over a considerable parameter range. A linear stability analysis and a numerical investigation of the second attractor reveal that the bifurcations producing the second attractor occur naturally in this type of system.Comment: 8 pages, 3 figure

Single-qubit unitary gates by graph scattering

We consider the effects of plane-wave states scattering off finite graphs, as an approach to implementing single-qubit unitary operations within the continuous-time quantum walk framework of universal quantum computation. Four semi-infinite tails are attached at arbitrary points of a given graph, representing the input and output registers of a single qubit. For a range of momentum eigenstates, we enumerate all of the graphs with up to $n=9$ vertices for which the scattering implements a single-qubit gate. As $n$ increases, the number of new unitary operations increases exponentially, and for $n>6$ the majority correspond to rotations about axes distributed roughly uniformly across the Bloch sphere. Rotations by both rational and irrational multiples of $\pi$ are found.Comment: 8 pages, 7 figure

Longitudinal Beam Stabilization at FAIR by Means of a Derivative Estimation

During acceleration in SIS18/SIS100 at GSI/FAIR longitudinal beam-oscillations are expected to occur. To reduce emittance blow-up, dedicated LLRF beam feedback systems are planned. To date longitudinal beam oscillations have been damped in machine experiments with a finite-impulse-response (FIR) filter controller with 3 filter taps. An alternative approach implementing the FIR filter as a derivative estimator controller is simulated and tested. This approach shares the same controller topology and can therefore be easily integrated in the system. It exploits the fact that the sampling rate of the feedback hardware is considerably higher than the frequency of the beam oscillations. It is therefore capable of damping oscillations without overshoot within one oscillation period

Tuning of 3-tap Bandpass Filter During Acceleration for Longitudinal Beam Stabilization at FAIR

During acceleration in the heavy-ion synchrotrons SIS18/SIS100 at GSI/FAIR longitudinal beam oscillations are expected to occur. To reduce longitudinal emittance blowup, dedicated LLRF beam feedback systems are planned. To date, damping of longitudinal beam oscillations has been demonstrated in SIS18 machine experiments with a 3-tap filter controller (e.g. [1]), which is robust in regard to control parameters and also to noise. On acceleration ramps the control parameters have to be adjusted to the varying synchrotron frequency. Previous results from beam experiments at GSI indicate that a proportional tuning rule for one parameter and an inversely proportional tuning rule for a second parameter is feasible, but the obtained damping rate may not be optimal for all synchrotron frequencies during the ramp. In this work, macro-particle simulations are performed to evaluate, whether it is sufficient to adjust the control parameters proportionally (inversely proportionally) to the change in the linear synchrotron frequency, or if it is necessary to take more parameters, such as bunch-length and synchronous phase, into account to achieve stability and a considerable high damping rate for excited longitudinal dipole beam oscillations. This is done for single- and dual-harmonic acceleration ramps

Ultrafast in cellulo photoinduced dynamics processes of the paradigm molecular light switch [Ru(bpy)2dppz]2+

An in cellulo study of the ultrafast excited state processes in the paradigm molecular light switch [Ru(bpy)2dppz]2+ by localized pump-probe spectroscopy is reported for the first time. The localization of [Ru(bpy)2dppz]2+ in HepG2 cells is verified by emission microscopy and the characteristic photoinduced picosecond dynamics of the molecular light switch is observed in cellulo. The observation of the typical phosphorescence stemming from a 3MLCT state suggests that the [Ru(bpy)2dppz]2+ complex intercalates with the DNA in the nucleus. The results presented for this benchmark coordination compound reveal the necessity to study the photoinduced processes in coordination compounds for intracellular use, e.g. as sensors or as photodrugs, in the actual biological target environment in order to derive a detailed molecular mechanistic understanding of the excited-state properties of the systems in the actual biological target environment

Analysis of the long-range transport of the volcanic plume from the 2021 Tajogaite/Cumbre Vieja eruption to Europe using TROPOMI and ground-based measurements

The eruptions of the Tajogaite volcano on the western flank of the Cumbre Vieja ridge on the island of La Palma between September and December 2021 released large amounts of ash and SO2. Transport and dispersion of the volcanic emissions were monitored by ground-based stations and satellite instruments alike. In particular, the spectrometric fluorescence and Raman lidar RAMSES at the Lindenberg Meteorological Observatory measured the plume of the strongest Tajogaite eruption of 22–23 September 2021 over northeastern Germany four days later. This study provides an analysis of SO2 vertical column density (VCD) and layer height (LH) measurements of the volcanic plume obtained with Sentinel-5 Precursor/TROPOMI, which are compared to the observations at several stations across the Canary Islands. Furthermore, a new modeling approach based on TROPOMI SO2 VCD measurements and the HYSPLIT trajectory and dispersion model was developed which confirmed the link between Tajogaite eruptions and Lindenberg measurements. Modeled mean emission height at the volcanic vent is in excellent agreement with co-located TROPOMI SO2 LH and local lidar ash height measurements. Finally, a comprehensive discussion of the RAMSES measurements is presented. A new retrieval approach has been developed to estimate the microphysical properties of the volcanic aerosol

Design and tuning of digital filters for RF feedback loops in heavy-ion synchrotrons

Damping of longitudinal coherent bunched-beam oscillations are needed in SIS18 and SIS100 to stabilize the beam, prevent emittance growth and keep beamloss low during acceleration. In last year’s work several approaches of digital filters for beam-phase control have been examined. An FIR (finite impulse response) filter with 3 taps, cf. [1], has been successfully used at GSI in several machine experiments for a beam- phase control system and a longitudinal feedback system. In principle, much more taps can be used, but it is still an open topic, whether more complex filters will lead to better results. Therefore, a detailed control-theoretic study has been started and the progress is reported in the following

Mitochondria Targeted Protein-Ruthenium Photosensitizer for Efficient Photodynamic Applications

Organelle-targeted photosensitization represents a promising approach in photodynamic therapy where the design of the active photosensitizer (PS) is very crucial. In this work, we developed a macromolecular PS with multiple copies of mitochondria-targeting groups and ruthenium complexes that displays highest phototoxicity toward several cancerous cell lines. In particular, enhanced anticancer activity was demonstrated in acute myeloid leukemia cell lines, where significant impairment of proliferation and clonogenicity occurs. Finally, attractive two-photon absorbing properties further underlined the great significance of this PS for mitochondria targeted PDT applications in deep tissue cancer therapy

Systemic therapy for advanced gastrointestinal stromal tumors: Beyond imatinib

Progression on first‐line therapy with imatinib in gastrointestinal stromal tumors (GIST) is caused by either initial resistance or more often a secondary mutation in tyrosine kinases KIT or PDGFR. Therapies in development for imatinib‐resistant GIST include agents that target KIT/PDGFR with greater potency or possess broader kinase inhibition profiles including VEGFR. To circumvent secondary mutations in KIT/PDGFR, inhibition of the downstream signaling in PI3K/Akt/mTOR pathway and enhanced degradation of KIT/PDGFR are also under investigation. J. Surg. Oncol. 2011; 104:901–906. © 2011 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/88097/1/21872_ftp.pd

The Complete Star Formation History of the Universe

The determination of the star-formation history of the Universe is a key goal of modern cosmology, as it is crucial to our understanding of how structure in the Universe forms and evolves. A picture has built up over recent years, piece-by-piece, by observing young stars in distant galaxies at different times in the past. These studies indicated that the stellar birthrate peaked some 8 billion years ago, and then declined by a factor of around ten to its present value. Here we report on a new study which obtains the complete star formation history by analysing the fossil record of the stellar populations of 96545 nearby galaxies. Broadly, our results support those derived from high-redshift galaxies elsewhere in the Universe. We find, however, that the peak of star formation was more recent - around 5 billion years ago. Our study also shows that the bigger the stellar mass of the galaxy, the earlier the stars were formed. This striking result indicates a very different formation history for high- and low-mass formation.Comment: Accepted by Nature. Press embargo until publishe