1,355 research outputs found
BIOCHEMICAL AND GENETIC-ANALYSIS OF RHIZOBIUM-MELILOTI MUTANTS DEFECTIVE IN C-4-DICARBOXYLATE TRANSPORT
No full textENGELKE T, JAGADISH MN, Pühler A. BIOCHEMICAL AND GENETIC-ANALYSIS OF RHIZOBIUM-MELILOTI MUTANTS DEFECTIVE IN C-4-DICARBOXYLATE TRANSPORT. JOURNAL OF GENERAL MICROBIOLOGY. 1987;133:3019-3029
IDENTIFICATION AND SEQUENCE-ANALYSIS OF THE RHIZOBIUM-MELILOTI DCTA GENE ENCODING THE C-4-DICARBOXYLATE CARRIER
No full textEngelke T, Jording D, Kapp D, Pühler A. IDENTIFICATION AND SEQUENCE-ANALYSIS OF THE RHIZOBIUM-MELILOTI DCTA GENE ENCODING THE C-4-DICARBOXYLATE CARRIER. JOURNAL OF BACTERIOLOGY. 1989;171(10):5551-5560
Application of acute maximal exercise to protect orthostatic tolerance after simulated microgravity
No full text Pages R837–R847: K. A. Engelke, D. F. Doerr, and V. A. Convertino. “Application of acute maximal exercise to protect orthostatic tolerance after simulated microgravity.” On p. 837, the author line of the article and abstract and the affiliation line should read as follows: KEITH A. ENGELKE, DONALD F. DOERR,CRAIG G. CRANDALL, AND VICTOR A. CONVERTINO Department of Physiology, University of Florida, Gainesville, Florida 32610; National Aeronautics and Space Administration-Kennedy Space Center, Cape Canaveral, Florida 32899;Department of Physiology, University of North Texas Health Science Center, Ft. Worth, Texas 76107; and Physiology Research Branch, Clinical Science Division, Brooks Air Force Base, Texas 78235 </jats:p
Application of acute maximal exercise to protect orthostatic tolerance after simulated microgravity
No full text Pages R837–R847: K. A. Engelke, D. F. Doerr, and V. A. Convertino. “Application of acute maximal exercise to protect orthostatic tolerance after simulated microgravity.” On p. 837, the author line of the article and abstract and the affiliation line should read as follows: KEITH A. ENGELKE, DONALD F. DOERR, CRAIG G. CRANDALL, AND VICTOR A. CONVERTINO Department of Physiology, University of Florida, Gainesville, Florida 32610; National Aeronautics and Space Administration-Kennedy Space Center, Cape Canaveral, Florida 32899; Department of Physiology, University of North Texas Health Science Center, Ft. Worth, Texas 76107; and Physiology Research Branch, Clinical Science Division, Brooks Air Force Base, Texas 78235 </jats:p
Lipid-coated zinc oxide nanocrystals as innovative ROS-generators for photodynamic therapy
No full textPhotodynamic Therapy (PDT) is a medical treatment that combines the administration of a nontoxic drug, called photosensitizer (PS), with light irradiation of the targeted region. It has been proposed as a new cancer therapy, promising better selectivity and fewer side-effects compared to traditional chemo- and radio-therapies. PSs indeed can accumulate specifically within the region of interest so that when the light is directly focused only in that region the therapeutic effect is highly localized. Traditional PSs, like chlorins and porphyrins, suffer from several drawbacks such as aggregation in biological media and poor biocompatibility. Thus, the development of innovative photosensitizers able to overcome these issues is crucial to the therapeutic action of PDT. Among the others, nanostructured Zinc Oxide (ZnO) has been recently proposed as new therapeutic agent and PS thanks to its semiconducting properties, biocompatible features, and ease of functionalization [1]. Nevertheless, further efforts are needed in order to improve its colloidal stability in biological media and to unravel the effective therapeutic mechanism. Here, we propose the synthesis and characterization of lipid-coated ZnO nanoparticles as new photosensitizer for cancer PDT [2]. First, by Dynamic Light Scattering (DLS) experiments, we show that the lipid-coating increases the colloidal stability of the ZnO NPs in Phosphate buffered saline (PBS). Then, using Electron Paramagnetic Resonance (EPR) coupled with the spin-trapping technique, we demonstrate and characterize the ability of bare and lipid-coated ZnO NPs to generate Reactive Oxygen Species (ROS) in water only when remotely actuated via light irradiation. Interestingly, our results aware that the surface chemistry of the NPs greatly influence the type of photo-generated ROS. Finally, we show that our NPs are effectively internalized inside human epithelial carcinoma cells (HeLa) via a lysosomal pathway and that they are able to generate ROS inside cancer cells. [1] B. Dumontel, M. Canta, H. Engelke, A. Chiodoni, L. Racca, A. Ancona, T. Limongi, G. Canavese and V. Cauda, J. Mater. Chem. B. under revision. [2] A. Ancona, H. Engelke, N. Garino, B. Dumontel, W.Fazzini and V. Cauda, to be submitted. The support from ERC Starting Grant - Project N. 678151 "Trojananohorse" is gratefully acknowledged
A UNIFYING APPROACH TO FRACTIONAL LEVY PROCESSES
No full textStarting from the moving average representation of fractional Brownian motion, there are two different approaches to constructing fractional Levy processes in the literature. Applying L-2-integration theory, one can keep the same moving average kernel and replace the driving Brownian motion by a pure jump Levy process with finite second moments. Alternatively, in the framework of alpha-stable random measures, the Brownian motion is replaced by an alpha-stable Levy process and the exponent in the kernel is reparametrized by H - 1/alpha. We now provide a unified approach taking kernels of the form a((t - s)(+)(gamma) - (-s)(+)(gamma)) + b((t - s)(-)(gamma) -(-s)(-)(gamma)), where gamma can be chosen according to the existing moments and the Blumenthal-Getoor index of the underlying Levy process. These processes may exhibit both long and short range dependence. In addition we will examine further properties of the processes, e. g., regularity of the sample paths and the semimartingale property.Deutsche Telekom Stiftung; Deutsche Forschungsgemeinschaft [SFB 823
Design Recommendations for Augmented Reality based Training of Maintenance Skills
No full textTraining for service technicians inmaintenance tasks is a classical application field of Augmented Reality explored by different research groups. Mostly technical aspects (tracking, visualization etc.) have been in focus of this research field. In this chapter we present results of interdisciplinary research based on the fusion of cognitive science, psychology and computer science. We focus on analyzing the improvement of Augmented Reality based training of skills which are relevant for maintenance and assembly tasks. The skills considered in this work comprise sensorimotor skills as well as cognitive skills. Different experiments have been conducted in order to find recommendations for the design of Augmented Reality training systems which overcome problems of existing approaches. The suggestions concern the fields of content visualization and multimodal feedback
Estimation of Hüsler-Reiss distributions and Brown-Resnick processes
No full textEstimation of extreme value parameters from observations in the max-domain of attraction of a multivariate max-stable distribution commonly uses aggregated data such as block maxima. Multivariate peaks-over-threshold methods, in contrast, exploit additional information from the non-aggregated 'large' observations. We introduce an approach based on peaks over thresholds that provides several new estimators for processes eta in the max-domain of attraction of the frequently used Husler-Reiss model and its spatial extension: Brown-Resnick processes. The method relies on increments eta(.) - eta t(0)/conditional on eta t(0)/exceeding a high threshold, where t(0) is a fixed location. When the marginals are standardized to the Gumbel distribution, these increments asymptotically form a Gaussian process resulting in computationally simple estimates of the Husler-Reiss parameter matrix and particularly enables parametric inference for Brown-Resnick processes based on (high dimensional) multivariate densities. This is a major advantage over composite likelihood methods that are commonly used in spatial extreme value statistics since they rely only on bivariate densities. A simulation study compares the performance of the new estimators with other commonly used methods. As an application, we fit a non-isotropic Brown-Resnick process to the extremes of 12-year data of daily wind speed measurements
Construction of a liquid-state NMR DNP shuttle spectrometer: first experimental results and evaluation of optimal performance characteristics.
No full textFirst results from a liquid-state shuttle dynamic nuclear polarization (DNP) spectrometer are presented. The device polarizes a water sample at 9.7 GHz and 0.34 T in a commercial Bruker electron paramagnetic resonance (EPR) spectrometer and then transfers the sample via a homebuilt pneumatic shuttle device into the 600 MHz and 14.09 T nuclear magnetic resonance (NMR) spectrometer with a conventional NMR probe for detection. The shuttle transfer time is approximately 115 ms. Initial experiments measure the postshuttle proton magnetization compared with the Boltzmann magnetization at 14.09 T. The DNP enhancement factor at 0.34 T is reported for the nitroxide polarizer TEMPOL in water solution. Reduction of the magnetization during shuttling because of relaxation is quantified. Optimization of this apparatus is expected to bring the NMR enhancement factor for protons close to the theoretical enhancement maximum of -7.92
Quantitative Ultrasound of Cortical Bone in the Femoral Neck Predicts Femur Strength: Results of a Pilot Study
No full textArticle first published online: 15 JAN 2013 Pour consulter la version éditeur DOI: 10.1002/jbmr.1742A significant risk of femoral neck (FN) fracture exists for men and women with an areal bone mineral density (aBMD) higher than the osteoporotic range, as measured with dual-energy X-ray absorptiometry (DXA). Separately measuring the cortical and trabecular FN compartments and combining the results would likely be a critical aspect of enhancing the diagnostic capabilities of a new technique. Because the cortical shell determines a large part of FN strength a novel quantitative ultrasound (QUS) technique that probes the FN cortical compartment was implemented, aimed at testing the sensitivity of the method to variations of FN cortical properties and FN strength. Nine femurs (women, mean age 83 years) were subjected to QUS to measure the through transmission time-of-flight (TOF) at the FN and mechanical tests to assess strength. Quantitative computed tomography (QCT) scans were performed to enable analysis of the dependence of TOF on bone parameters. DXA was also performed for reference. An ultrasound wave propagating circumferentially in the cortical shell, which TOF was not influenced by the properties of the trabecular compartment Q3, was measured in all specimens. Averaged TOF for nine FN measurement positions/orientations was significantly correlated to strength (R² = 0.79) and FN cortical QCT variables: total BMD (R² = 0.54); regional BMD in the inferoanterior (R² = 0.90) and superoanterior (R² = 0.57) quadrants; and moment of inertia (R² = 0.71). The results of this study demonstrate that QUS can perform a targeted measurement of the FN cortical compartment. Because the method involves mechanical guided waves, the QUS variable is related to the geometric and material properties of the cortical shell (cortical thickness, tissue elasticity, and porosity). This work opens the way to a multimodal QUS assessment of the proximal femur, combining our approach targeting the cortical shell with the existing modality sensitive to the trabecular compartment. In vivo feasibility of our approach has to be confirmed with experimental data in patients
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