Tunable multi-photon Rabi oscillations in an electronic spin system

We report on multi-photon Rabi oscillations and controlled tuning of a multi-level system at room temperature (S=5/2 for Mn2+:MgO) in and out of a quasi-harmonic level configuration. The anisotropy is much smaller than the Zeeman splittings, such as the six level scheme shows only a small deviation from an equidistant diagram. This allows us to tune the spin dynamics by either compensating the cubic anisotropy with a precise static field orientation, or by microwave field intensity. Using the rotating frame approximation, the experiments are very well explained by both an analytical model and a generalized numerical model. The calculated multi-photon Rabi frequencies are in excellent agreement with the experimental data

Coherent manipulation of electron spins up to ambient temperatures in Cr5+^{5+}(S=1/2) doped K3_3NbO8_8

We report coherent spin manipulation on Cr$^{5+}$ (\emph{S} = 1/2, \emph{I} = 0) doped K$_3$NbO$_8$, which constitutes a dilute two-level model relevant for use as a spin qubit. Rabi oscillations are observed for the first time in a spin system based on transition metal oxides up to room temperature. At liquid helium temperature the phase coherence relaxation time \emph{$T_2$} reaches $\sim 10$ $\mu$s and, with a Rabi frequency of 20 MHz, yields a single qubit figure of merit \emph{$Q_M$} of about 500. This shows that a diluted ensemble of Cr$^{5+}$ (\emph{S} = 1/2) doped K$_3$NbO$_8$ is a potential candidate for solid-state quantum information processing.Comment: 4 page

Statistical model of the powder flow regulation by nanomaterials

Fine powders often tend to agglomerate due to van der Waals forces between the particles. These forces can be reduced significantly by covering the particles with nanoscaled adsorbates, as shown by recent experiments. In the present work a quantitative statistical analysis of the effect of powder flow regulating nanomaterials on the adhesive forces in powders is given. Covering two spherical powder particles randomly with nanoadsorbates we compute the decrease of the mutual van der Waals force. The dependence of the force on the relative surface coverage obeys a scaling form which is independent of the used materials. The predictions by our simulations are compared to the experimental results.Comment: 18 pages, 9 figures, 1 table, LaTeX; reviewed version with minor changes, published (Powder Technology

Multiphoton Resonances in Pulse EPR

Two- and three-photon electron spin echoes of a two-level system are observed using, in addition to the microwave excitation, a linearly polarized radio-frequency field oriented along the static magnetic field B0. Such multiphoton echoes are detected when the sum of the energies of one microwave and one or two radio-frequency photons are equal to the difference between energies of two spin states. The multiphoton character of the echoes is confirmed by measuring the spin nutation frequency as a function of the angle between the radio-frequency field and B0, and monitoring the echo amplitude as a function of the radiation field strengths. Floquet theory, usually applied for the description of multiphoton resonances with an odd number of photons, is extended to the case where an even number of photons participate in the transition. © 2000 Academic Press

Serological diagnosis of echinococcosis: the diagnostic potential of native antigens

Purpose: Human alveolar (AE) and cystic echinococcosis (CE) caused by the metacestode stages of Echinococcus multilocularis and E. granulosus, respectively, lack pathognomonic clinical signs. Diagnosis therefore relies on the results of imaging and serological studies. The primary goal of this study was to evaluate the efficacy of several easy-to-produce crude or partially purified E. granulosus and E. multilocularis metacestode-derived antigens as tools for the serological diagnosis and differential diagnosis of patients suspicious for AE or CE. Methods: The sera of 51 treatment-naïve AE and 32 CE patients, 98 Swiss blood donors and 38 patients who were initially suspicious for echinococcosis but suffering from various other liver diseases (e.g., liver neoplasia, etc.) were analysed. Results: According to the results of enzyme-linked immunosorbent assays (ELISA), metacestode-derived antigens of E. granulosus had sensitivities varying from 81 to 97% and >99.9% for the diagnosis of CE and AE, respectively. Antigens derived from E. multilocularis metacestodes had sensitivities ranging from 84 to 91% and >99.9% for the diagnosis of CE and AE, respectively. Specificities ranged from 92 to >99.9%. Post-test probabilities for the differential diagnosis of AE from liver neoplasias, CE from cystic liver lesions, and screening for AE in Switzerland were around 95, 86 and 2.2%, respectively. Cross-reactions with antibodies in sera of patients with other parasitic affections (fasciolosis, schistosomosis, amebosis, cysticercosis, and filarioses) did occur at variable frequencies, but could be eliminated through the use of confirmatory testing. Conclusions: Different metacestode-derived antigens of E. granulosus and E. multilocularis are valuable, widely accessible, and cost-efficient tools for the serological diagnosis of echinococcosis. However, confirmatory testing is necessary, due to the lack of species specificity and the occurrence of cross-reactions to other helminthic disease

[18F]Fluoro-2-Deoxy-D-Glucose Incorporation by MCF-7 Breast Tumour Cells In Vitro Is Modulated by Treatment with Tamoxifen, Doxorubicin, and Docetaxel: Relationship to Chemotherapy-Induced Changes in ATP Content, Hexokinase Activity, and Glucose Transport

Breast tumours responding to chemotherapy exhibit decreased [18F]fluoro-2-deoxy-D-glucose ([18F]FDG) incorporation. Underlying mechanisms of these changes is poorly understood. Here, in MCF-7 cells, responding to chemotherapy drugs commonly utilised in the treatment of breast cancer, [18F]FDG incorporation and several pivotal factors associated with [18F]FDG incorporation investigated. Methods. IC50 and subclinical doxorubicin, docetaxel, and tamoxifen doses determined using MTT assay. [18F]FDG incorporation by cells treated with IC50 drug doses for 48 hours and 72 hours were determined and FDG dephosphorylation estimated by measuring loss of 18F from [18F]FDG-preincubated cells (pulse-chase). Glucose transport determined by measuring initial uptake rate of non-metabolised glucose analogue omethylglucose; hexokinase activity and ATP content measured in cell homogenates; Cell cycle distribution determined using flow cytometry of propidium iodide stained nuclei. Results. [18F]FDG incorporation and ATP content decreased in cells after 72 hours treatment with IC50 doses of tamoxifen, doxorubicin, and docetaxel compared with untreated controls. Decreased glucose transport and/or hexokinase activity accompanied decreased [18F]FDG incorporation by MCF-7 cells treated with tamoxifen or doxorubicin but not docetaxel. Conclusions. Tumour cell [18F]FDG incorporation along with ATP content decreased by treatment with tamoxifen, doxorubicin and docetaxel paralleling clinical observations for solid tumours. Effect of each treatment on glucose transport and hexokinase activity was chemotherapy-drug dependent

The continuous wave electron paramagnetic resonance experiment revisited

When the modulation frequency used in continuous wave electron paramagnetic resonance (cw EPR) spectroscopy exceeds the linewidth, modulation sidebands appear in the spectrum. It is shown theoretically and experimentally that these sidebands are actually multiple photon transitions, σ++k × π, where one microwave (mw) σ+ photon is absorbed from the mw radiation field and an arbitrary number k of radio frequency (rf) π photons are absorbed from or emitted to the modulation rf field. Furthermore, it is demonstrated that both the derivative shape of the lines in standard cw EPR spectra and the distortions due to overmodulation are caused by the unresolved sideband pattern of these lines. The single-photon transition does not even give a contribution to the first-harmonic cw EPR signal. Multiple photon transitions are described semiclassically in a toggling frame and their existence is proven using second quantization. With the toggling frame approach and perturbation theory an effective Hamiltonian for an arbitrary sideband transition is derived. Based on the effective Hamiltonians an expression for the steady-state density operator in the singly rotating frame is derived, completely describing all sidebands in all modulation frequency harmonics of the cw EPR signal. The relative intensities of the sidebands are found to depend in a very sensitive way on the actual rf amplitude and the saturation of single sidebands is shown to depend strongly on the effective field amplitude of the multiple photon transitions. By comparison with the analogous solutions for frequency-modulation EPR it is shown that the field-modulation and the frequency-modulation technique are not equivalent. The experimental data fully verify the theoretical predictions with respect to intensities and lineshapes. © 2003 Elsevier Science (USA). All rights reserved

An operational definition of the biome for global change research

CITATION: Conradi, T. et al. 2020. An operational definition of the biome for global change research. New Phytologist, 227:1294–1306, doi:10.1111/nph.16580.The original publication is available at https://nph.onlinelibrary.wiley.comBiomes are constructs for organising knowledge on the structure and functioning of the world’s ecosystems, and serve as useful units for monitoring how the biosphere responds to anthropogenic drivers, including climate change. The current practice of delimiting biomes relies on expert knowledge. Recent studies have questioned the value of such biome maps for comparative ecology and global-change research, partly due to their subjective origin. Here we propose a flexible method for developing biome maps objectively. The method uses range modelling of several thousands of plant species to reveal spatial attractors for different growth-form assemblages that define biomes. The workflow is illustrated using distribution data from 23 500 African plant species. In an example application, we create a biome map for Africa and use the fitted species models to project biome shifts. In a second example, we map gradients of growth-form suitability that can be used to identify sites for comparative ecology. This method provides a flexible framework that (1) allows a range of biome types to be defined according to user needs and (2) enables projections of biome changes that emerge purely from the individualistic responses of plant species to environmental changes.Publisher's versio

Feasibility of Group Schema Therapy for Outpatients with Severe Borderline Personality Disorder in Germany:A Pilot Study with Three Year Follow-Up

Borderline Personality Disorder (BPD) is a severe, challenging to treat mental disorder. Schema therapy (ST) as an individual therapy has been proven to be an effective psychological treatment for BPD. A group format of ST (GST) has been developed and evaluated in a randomized controlled trial in the United States and piloted in The Netherlands. These results suggest that GST speeds up and amplifies treatment effects of ST and might reduce delivery costs. However, feasibility in the German health care system and with BPD patients with high BPD severity and comorbidity, and frequent hospitalization, has not been tested to date. We investigated GST in 10 severely impaired, highly comorbid female patients with BPD, that needed frequent hospital admission. Patients received an outpatient ST-treatment program with weekly group and individual sessions for 1 year. Outcome measures including BPD severity, general psychopathology, psychosocial functioning, quality of life, happiness, schemas, and modes, and days of hospitalization were assessed at the start of treatment and 6, 12, and 36 months later with semi-structured interviews and self-report measures. We observed significant decreases in severity of BPD symptoms, general symptom severity, dysfunctional BPD-specific modes and schemas, and days of hospitalization. Functional modes, quality of live and happiness improved. The results of this feasibility study are promising and encourage further implementation of ST outpatient treatment programs even for patients with severe BPD and high hospitalization risk. However, small sample size and the missing of a control group do not allow the generalizability of these findings