Interplay between the electrical transport properties of GeMn thin films and Ge substrates

We present evidence that electrical transport studies of epitaxial p-type GeMn thin films fabricated on high resistivity Ge substrates are severely influenced by parallel conduction through the substrate, related to the large intrinsic conductivity of Ge due to its small bandgap. Anomalous Hall measurements and large magneto resistance effects are completely understood by taking a dominating substrate contribution as well as the measurement geometry into account. It is shown that substrate conduction persists also for well conducting, degenerate, p-type thin films, giving rise to an effective two-layer conduction scheme. Using n-type Ge substrates, parallel conduction through the substrate can be reduced for the p-type epi-layers, as a consequence of the emerging pn-interface junction. GeMn thin films fabricated on these substrates exhibit a negligible magneto resistance effect. Our study underlines the importance of a thorough characterization and understanding of possible substrate contributions for electrical transport studies of GeMn thin films.Comment: 9 pages, 9 figure

A scalable architecture for quantum computation with molecular nanomagnets

A proposal for a magnetic quantum processor that consists of individual molecular spins coupled to superconducting coplanar resonators and transmission lines is carefully examined. We derive a simple magnetic quantum electrodynamics Hamiltonian to describe the underlying physics. It is shown that these hybrid devices can perform arbitrary operations on each spin qubit and induce tunable interactions between any pair of them. The combination of these two operations ensures that the processor can perform universal quantum computations. The feasibility of this proposal is critically discussed using the results of realistic calculations, based on parameters of existing devices and molecular qubits. These results show that the proposal is feasible, provided that molecules with sufficiently long coherence times can be developed and accurately integrated into specific areas of the device. This architecture has an enormous potential for scaling up quantum computation thanks to the microscopic nature of the individual constituents, the molecules, and the possibility of using their internal spin degrees of freedom.Comment: 27 pages, 6 figure

Reconstruction of the two-dimensional gravitational potential of galaxy clusters from X-ray and Sunyaev-Zel'dovich measurements

The mass of galaxy clusters is not a direct observable, nonetheless it is commonly used to probe cosmological models. Based on the combination of all main cluster observables, that is, the X-ray emission, the thermal Sunyaev-Zel'dovich (SZ) signal, the velocity dispersion of the cluster galaxies, and gravitational lensing, the gravitational potential of galaxy clusters can be jointly reconstructed. We derive the two main ingredients required for this joint reconstruction: the potentials individually reconstructed from the observables and their covariance matrices, which act as a weight in the joint reconstruction. We show here the method to derive these quantities. The result of the joint reconstruction applied to a real cluster will be discussed in a forthcoming paper. We apply the Richardson-Lucy deprojection algorithm to data on a two-dimensional (2D) grid. We first test the 2D deprojection algorithm on a $\beta$-profile. Assuming hydrostatic equilibrium, we further reconstruct the gravitational potential of a simulated galaxy cluster based on synthetic SZ and X-ray data. We then reconstruct the projected gravitational potential of the massive and dynamically active cluster Abell 2142, based on the X-ray observations collected with XMM-Newton and the SZ observations from the Planck satellite. Finally, we compute the covariance matrix of the projected reconstructed potential of the cluster Abell 2142 based on the X-ray measurements collected with XMM-Newton. The gravitational potentials of the simulated cluster recovered from synthetic X-ray and SZ data are consistent, even though the potential reconstructed from X-rays shows larger deviations from the true potential. Regarding Abell 2142, the projected gravitational cluster potentials recovered from SZ and X-ray data reproduce well the projected potential inferred from gravitational-lensing observations. (abridged)Comment: accepted for publication in the journal A&

Cranio-cerebral gunshot wounds

Cranio-cerebral gunshots wounds (CCGW) are the most devastating injuries to the central nervous system, especially made by high velocity bullets, the most devastating, severe and usually fatal type of missile injury to the head. Objective: To investigate and compare, using a retrospective study on five cases the clinical outcomes of CCGW. Predictors of poor outcome were: older age, delayed mode of transportation, low admission CGS score with haemodynamic instability, CT visualization of diffuse brain damage, bihemispheric, multilobar injuries with lateral and midline sagittal planes trajectories made by penetrating high velocity bullets fired from a very close range, brain stem and ventricular injury with intraventricular and/or subarachnoid hemorrhage, mass effect and midline shift, evidence of herniation and/or hematomas, high ICP and/or hypotension, abnormal coagulation states on admission or disseminated intravascular coagulation. Less harmful effects were generated by retained missiles, bone fragments with CNS infection, DAI lesions and neuronal damages associated to cavitation, seizures. Material and methods: 5 patients (4 male and 1 female), age ranged 22-65 years, with CCGW, during the period 2004-2009, caused by military conflict and accidental firing. After initial resuscitation all patients were assessed on admission by the Glasgow Coma Scale (GCS). After investigations: X-ray skull, brain CT, Angio-CT, cerebral MRI, SPECT; baseline investigations, neurological, haemodynamic and coagulability status all patients underwent surgical treatment following emergency intervention. The survival, mortality and functional outcome were evaluated by Glasgow Outcome Scale (GOS) score. Results: Referring on five cases we evaluate on a retrospective study the clinical outcome, imagistics, microscopic studies on neuronal and axonal damage generated by temporary cavitation along the cerebral bullet’s track, therapeutics, as the review of the literature. Two patients with an admission CGS 9 and 10 survived and three patients with admission CGS score of 3, with severe ventricular, brain stem injuries and lateral plane of high velocity bullets trajectories died despite treatment.Conclusion: CCGW is the most devastating type of missile injury to the head. Aggressive intensive care management in combination with early management with less aggressive meticulous neurosurgical technique, has significantly reduced the mortality and morbidity associated with these injuries, but they still remain unacceptably high. Primary prevention of these injuries remains important, the patient must be monitored closely for possible complications

Spectroscopy on two coupled flux qubits

We have performed spectroscopy measurements on two coupled flux qubits. The qubits are coupled inductively, which results in a $\sigma_1^z\sigma_2^z$ interaction. By applying microwave radiation, we observe resonances due to transitions from the ground state to the first two excited states. From the position of these resonances as a function of the magnetic field applied we observe the coupling of the qubits. The coupling strength agrees well with calculations of the mutual inductance

Release from UNC93B1 reinforces the compartmentalized activation of select TLRs

Nucleic acid-sensing Toll-like receptors (TLRs) are subject to complex regulation to facilitate the recognition of microbial DNA and RNA while limiting the recognition of an organism's own nucleic acids1. Failure to properly regulate these TLRs can lead to autoimmune and autoinflammatory diseases2-6. Intracellular localization of these receptors is thought to be crucial for the discrimination between self and non-self7, but the molecular mechanisms that reinforce compartmentalized activation of intracellular TLRs remain poorly understood. Here we describe a mechanism that prevents the activation of TLR9 from locations other than endosomes. This control is achieved through the regulated release of the receptor from its trafficking chaperone UNC93B1, which occurs only within endosomes and is required for ligand binding and signal transduction. Preventing release of TLR9 from UNC93B1, either by mutations in UNC93B1 that increase affinity for TLR9 or through an artificial tether that impairs release, results in defective signalling. Whereas TLR9 and TLR3 are released from UNC93B1, TLR7 does not dissociate from UNC93B1 in endosomes and is regulated by distinct mechanisms. This work defines a checkpoint that reinforces the compartmentalized activation of TLR9, and provides a mechanism by which activation of individual endosomal TLRs may be distinctly regulated