Modeling and Analysis of Power Processing Systems

The feasibility of formulating a methodology for the modeling and analysis of aerospace electrical power processing systems is investigated. It is shown that a digital computer may be used in an interactive mode for the design, modeling, analysis, and comparison of power processing systems

Identification of a Novel, Small Molecule Partial Agonist for the Cyclic AMP Sensor, EPAC1

Screening of a carefully selected library of 5,195 small molecules identified 34 hit compounds that interact with the regulatory cyclic nucleotide-binding domain (CNB) of the cAMP sensor, EPAC1. Two of these hits (I942 and I178) were selected for their robust and reproducible inhibitory effects within the primary screening assay. Follow-up characterisation by ligand observed nuclear magnetic resonance (NMR) revealed direct interaction of I942 and I178 with EPAC1 and EPAC2-CNBs in vitro. Moreover, in vitro guanine nucleotide exchange factor (GEF) assays revealed that I942 and, to a lesser extent, I178 had partial agonist properties towards EPAC1, leading to activation of EPAC1, in the absence of cAMP, and inhibition of GEF activity in the presence of cAMP. In contrast, there was very little agonist action of I942 towards EPAC2 or protein kinase A (PKA). To our knowledge, this is the first observation of non-cyclic-nucleotide small molecules with agonist properties towards EPAC1. Furthermore, the isoform selective agonist nature of these compounds highlights the potential for the development of small molecule tools that selectively up-regulate EPAC1 activity

Glucagon-like peptide-1 (GLP-1) receptors are not overexpressed in pancreatic islets from patients with severe hyperinsulinaemic hypoglycaemia following gastric bypass

Aims/hypothesis: Glucagon-like peptide-1 (GLP-1) receptors are highly overexpressed in benign insulinomas, permitting in vivo tumour visualisation with GLP-1 receptor scanning. The present study sought to evaluate the GLP-1 receptor status in vitro in other pancreatic disorders leading to hyperinsulinaemic hypoglycaemia, specifically after gastric bypass surgery. Methods: Fresh frozen pancreatic tissue samples (n = 7) from six gastric bypass surgery patients suffering from hyperinsulinaemic hypoglycaemia were evaluated for GLP-1 receptor content using in vitro receptor autoradiography, and compared with normal pancreas and with pancreatic insulinoma tissues. Results: GLP-1 receptor analysis of the pancreatic tissues, which histopathologically were compatible with nesidioblastosis and originated from post-bypass hypoglycaemic patients, revealed a mean density value of GLP-1 receptors in the islets of 1,483 ± 183dpm/mg tissue. Pharmacological characterisation indicated the presence of specific GLP-1 receptors. The density of islet GLP-1 receptor in post-gastric bypass patients did not differ from that of normal pancreas (1,563 ± 104dpm/mg tissue, n = 10). Receptor density in pancreatic acini was low in post-bypass and control conditions. In contrast, benign insulinomas showed a high density of GLP-1 receptors, with a mean value of 8,302 ± 1,073dpm/mg tissue (n = 6). Conclusions/interpretation: In contrast to insulinoma, hyperinsulinaemic hypoglycaemia after gastric bypass surgery is not accompanied by overexpression of GLP-1 receptor in individual islets. Thus, patients with post-gastric bypass hyperinsulinaemic hypoglycaemia are not candidates for GLP-1 receptor imaging in vivo using radiolabelled exendin. These GLP-1 receptor data support the notion that the islet pathobiology of post-gastric bypass hypoglycaemia is distinctly different from that of benign insulinoma

Neutron dose rate at the SwissFEL injector test facility: first measurements

At the Paul Scherrer Institute, the new SwissFEL Free Electron Laser facility is currently in the design phase. It is foreseen to accelerate electrons up to a maximum energy of 7 GeV with a pulsed time structure. An injector test facility is operated at a maximum energy of 300 MeV and serves as the principal test and demonstration plant for the SwissFEL project. Secondary radiation is created in unavoidable interactions of the primary beam with beamline components. The resulting ambient dose-equivalent rate due to neutrons was measured along the beamline with different commercially available survey instruments. The present study compares the readings of these neutron detectors (one of them is specifically designed for measurements in pulsed fields). The experiments were carried out in both, a normal and a diagnostic mode of operation of the injecto

Theory of Interplay of Nuclear Magnetism and Superconductivity in AuIn2

The recently reported coexistence of a magnetic order, with the critical temperature T_M=35 \mu*K, and superconductivity, with the critical temperature T_S=207 m*K, in AuIn_2 is studied theoretically. It is shown that superconducting (S) electrons and localized nuclear magnetic moments (LM's) interact dominantly via the contact hyperfine (EX) interaction, giving rise to a spiral (or domain-like) magnetic order in superconducting phase. The electromagnetic interaction between LM's and S electrons is small compared to the EX one giving minor contribution to the formation of the oscillatory magnetic order. In clean samples (l>\xi_0) of AuIn$_2$ the oscillatory magnetic order should produce a line of nodes in the quasiparticle spectrum of S electrons giving rise to the power law behavior. The critical field H_c(T=0) in the coexistence phase is reduced by factor two with respect to its bare value.Comment: 4 pages with 2 PS figures, RevTeX, submitted to Physical Review B - Rapid Communication

De Novo Heterozygous POLR2A Variants Cause a Neurodevelopmental Syndrome with Profound Infantile-Onset Hypotonia

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Decoupling of superconducting layers in magnetic superconductor RuSr_{2}GdCu_{2}O_{8}

We propose the model for magnetic properties of the magnetic superconductor RuSr$_{2}$GdCu$_{2}$O$_{8}$, which incorporates the theory of the superconducting/ferromagnetic multilayers. The transition line $T_{d}(h)$, on which the Josephson coupled superconducting planes are decoupled, i.e. $j_{c}(T_{d})=0$, is calculated as a function of the exchange energy $h$. As the result of this decoupling a nonmonotonic behavior of magnetic properties, like the lower critical field $H_{c1}$, Josephson plasma frequency, etc. is realized near (or by crossing) the $T_{d}(h)$ line. The obtained results are used in analyzing the newly discovered antiferromagnetic ruthenocuprate RuSr$_{2}$GdCu$_{2}$O$_{8}$ with possible weak ferromagnetic order in the RuO planes.Comment: 12 pages, 3 figs embede

Strong spin-orbit interaction and gg-factor renormalization of hole spins in Ge/Si nanowire quantum dots

The spin-orbit interaction lies at the heart of quantum computation with spin qubits, research on topologically non-trivial states, and various applications in spintronics. Hole spins in Ge/Si core/shell nanowires experience a spin-orbit interaction that has been predicted to be both strong and electrically tunable, making them a particularly promising platform for research in these fields. We experimentally determine the strength of spin-orbit interaction of hole spins confined to a double quantum dot in a Ge/Si nanowire by measuring spin-mixing transitions inside a regime of spin-blockaded transport. We find a remarkably short spin-orbit length of $\sim$65 nm, comparable to the quantum dot length and the interdot distance. We additionally observe a large orbital effect of the applied magnetic field on the hole states, resulting in a large magnetic field dependence of the spin-mixing transition energies. Strikingly, together with these orbital effects, the strong spin-orbit interaction causes a significant enhancement of the $g$-factor with magnetic field.The large spin-orbit interaction strength demonstrated is consistent with the predicted direct Rashba spin-orbit interaction in this material system and is expected to enable ultrafast Rabi oscillations of spin qubits and efficient qubit-qubit interactions, as well as provide a platform suitable for studying Majorana zero modes