Boundary of Quantum Evolution under Decoherence

Relaxation effects impose fundamental limitations on our ability to coherently control quantum mechanical phenomena. In this letter, we establish physical limits on how closely can a quantum mechanical system be steered to a desired target state in the presence of relaxation. In particular, we explicitly compute the maximum coherence or polarization that can be transferred between coupled nuclear spins in the presence of very general decoherence mechanisms that include cross-correlated relaxation. We give analytical expressions for the control laws (pulse sequences) which achieve these physical limits and provide supporting experimental evidence. Exploitation of cross-correlation effects has recently led to the development of powerful methods in NMR spectroscopy to study very large biomolecules in solution. We demonstrate with experiments that the optimal pulse sequences provide significant gains over these state of the art methods, opening new avenues for spectroscopy of much larger proteins. Surprisingly, in spite of very large relaxation rates, optimal control can transfer coherence without any loss when cross-correlated relaxation rates are tuned to auto-correlated relaxation rates

Broadband Relaxation-Optimized Polarization Transfer in Magnetic Resonance

Many applications of magnetic resonance are limited by rapid loss of spin coherence caused by large transverse relaxation rates. In nuclear magnetic resonance (NMR) of large proteins, increased relaxation losses lead to poor sensitivity of experiments and increased measurement time. In this paper we develop broadband relaxation optimized pulse sequences (BB-CROP) which approach fundamental limits of coherence transfer efficiency in the presence of very general relaxation mechanisms that include cross-correlated relaxation. These broadband transfer schemes use new techniques of chemical shift refocusing (STAR echoes) that are tailored to specific trajectories of coupled spin evolution. We present simulations and experimental data indicating significant enhancement in the sensitivity of multi-dimensional NMR experiments of large molecules by use of these methods

Spin polarization of Auger- and of photoelectrons from barium atoms exposed to circularly polarized radiation and their cross comparison

Kuntze R, Salzmann M, Böwering N, Heinzmann U. Spin polarization of Auger- and of photoelectrons from barium atoms exposed to circularly polarized radiation and their cross comparison. Zeitschrift für Physik D: Atoms, Molecules and Clusters. 1994;30(2-3):235-237.New results of spin polarization of both photoelectrons and Auger electrons are reported after 5[Rho] photoionization of free Ba atoms with circularly polarized light. A substantial polarization transfer from the spin polarized photons to the spin polarized photoelectrons and via the hole state orientation to the spin polarized Auger-electrons is observed. The cross comparison of the results for photoelectrons and Auger-electrons allows a quantitative test of the assumed two step model where both electron-emission processes occur in sequence

Antibiotics in early life and childhood pre-B-ALL. Reasons to analyze a possible new piece in the puzzle

Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer with precursor B-cell ALL (pB-ALL) accounting for~85% of the cases. Childhood pB-ALL development is infuenced by genetic susceptibility and host immune responses. The role of the intestinal microbiome in leukemogenesis is gaining increasing attention since Vicente-Dueñas’ seminal work demonstrated that the gut microbiome is distinct in mice genetically predisposed to ALL and that the alteration of this microbiome by antibiotics is able to trigger pB-ALL in Pax5 heterozygous mice in the absence of infectious stimuli. In this review we provide an overview on novel insights on the role of the microbiome in normal and preleukemic hematopoiesis, infammation, the efect of dysbiosis on hematopoietic stem cells and the emerging importance of the innate immune responses in the conversion from preleukemic to leukemic state in childhood ALL. Since antibiotics, which represent one of the most widely used medical interventions, alter the gut microbial composition and can cause a state of dysbiosis, this raises exciting epidemiological questions regarding the implications for antibiotic use in early life, especially in infants with a a preleukemic “frst hit”. Sheading light through a rigorous study on this piece of the puzzle may have broad implications for clinical practice

Adaptive Data-Driven Predictive Control as a Module in Building Control Hierarchy: A Case Study of Demand Response in Switzerland

By providing various services, such as demand responses, buildings play a crucial role in the energy market due to their significant energy consumption. However, effectively commissioning buildings for desired functionality requires significant expert knowledge and design effort, considering the variations in building dynamics and intended use. In this study, we introduce an adaptive data-driven control scheme as a module within the building control hierarchy. This scheme offers a versatile, flexible, and user-friendly interface for different design objectives. We evaluate the proposed scheme by coordinating a building and an energy storage system to provide Secondary Frequency Control (SFC) in a Swiss demand response program. Specifically, we integrate the scheme into a three-layer hierarchical SFC control framework, and each layer of this hierarchy is designed to achieve distinct operational goals. Apart from its flexibility, our approach significantly enhances cost efficiency, resulting in a 24.64% and 28.74% reduction in operational costs compared to conventional control schemes. Our findings emphasize the potential of the proposed scheme to reduce the commissioning costs of advanced building control strategies and facilitate the adoption of new techniques in building control

Photoelectron spin polarization approaching unity: photoionization of TI

Böwering N, Salzmann M, Müller M, Klausing H-W, Heinzmann U. Photoelectron spin polarization approaching unity: photoionization of TI. Physica Scripta. 1990;41(4):429-432.It is shown that a complete photoelectron-spin polarization occurs independent of emission angle for two special sets of values of the dynamical photoionization parameters. In spin- and angle-resolved photoelectron spectroscopy of thallium the dynamical parameters were measured near the autoionization resonances at 149 nm and 82 nm. A pronounced angular variation of the polarization component A[Theta] was observed at 83 nm. For both resonances the parameters were found to approach different limiting values such that the length of the spin-polarization vector assumes values close to unity at all emission angles. The implications of these results for the corresponding dipole transition matrix elements are discussed

ActiveMoCap: Optimized Viewpoint Selection for Active Human Motion Capture

The accuracy of monocular 3D human pose estimation depends on the viewpoint from which the image is captured. While freely moving cameras, such as on drones, provide control over this viewpoint, automatically positioning them at the location which will yield the highest accuracy remains an open problem. This is the problem that we address in this paper. Specifically, given a short video sequence, we introduce an algorithm that predicts which viewpoints should be chosen to capture future frames so as to maximize 3D human pose estimation accuracy. The key idea underlying our approach is a method to estimate the uncertainty of the 3D body pose estimates. We integrate several sources of uncertainty, originating from deep learning based regressors and temporal smoothness. Our motion planner yields improved 3D body pose estimates and outperforms or matches existing ones that are based on person following and orbiting.Comment: For associated video, see https://youtu.be/i58Bu-hbZHs Published in CVPR 202

Photoassociation adiabatic passage of ultracold Rb atoms to form ultracold Rb_2 molecules

We theoretically explore photoassociation by Adiabatic Passage of two colliding cold ^{85}Rb atoms in an atomic trap to form an ultracold Rb_2 molecule. We consider the incoherent thermal nature of the scattering process in a trap and show that coherent manipulations of the atomic ensemble, such as adiabatic passage, are feasible if performed within the coherence time window dictated by the temperature, which is relatively long for cold atoms. We show that a sequence of ~2*10^7 pulses of moderate intensities, each lasting ~750 ns, can photoassociate a large fraction of the atomic ensemble at temperature of 100 microkelvin and density of 10^{11} atoms/cm^3. Use of multiple pulse sequences makes it possible to populate the ground vibrational state. Employing spontaneous decay from a selected excited state, one can accumulate the molecules in a narrow distribution of vibrational states in the ground electronic potential. Alternatively, by removing the created molecules from the beam path between pulse sets, one can create a low-density ensemble of molecules in their ground ro-vibrational state.Comment: RevTex, 23 pages, 9 figure

QCD corrections to the Wilson coefficients C9 and C10 in two-Higgs doublet models

In this letter we present the analytic results for the two-loop corrections to the Wilson coefficients C_9(mu_W) and C_10(mu_W) in type-I and type-II two-Higgs-doublet models at the matching scale mu_W. These corrections are important ingredients for next-to-next-to-leading logarithmic predictions of various observables related to the decays B -> X_s l^+ l^- in these models. In scenarios with moderate values of tan(beta) neutral Higgs boson contributions can be safely neglected for e,mu. Therefore we concentrate on the contributions mediated by charged Higgs bosons.Comment: 12 pages, 3 figure

Silent synapses generate sparse and orthogonal action potential firing in adult-born hippocampal granule cells.

In adult neurogenesis young neurons connect to the existing network via formation of thousands of new synapses. At early developmental stages, glutamatergic synapses are sparse, immature and functionally 'silent', expressing mainly NMDA receptors. Here we show in 2- to 3-week-old young neurons of adult mice, that brief-burst activity in glutamatergic fibers is sufficient to induce postsynaptic AP firing in the absence of AMPA receptors. The enhanced excitability of the young neurons lead to efficient temporal summation of small NMDA currents, dynamic unblocking of silent synapses and NMDA-receptor-dependent AP firing. Therefore, early synaptic inputs are powerfully converted into reliable spiking output. Furthermore, due to high synaptic gain, small dendritic trees and sparse connectivity, neighboring young neurons are activated by different distinct subsets of afferent fibers with minimal overlap. Taken together, synaptic recruitment of young neurons generates sparse and orthogonal AP firing, which may support sparse coding during hippocampal information processing