Micro-PIXE (Particle-Induced X-Ray Emission Analysis) Applications in Minerals Research

The versatility of the PIXE method with microbeams of protons as a non-destructive, in-situ probe for trace element analysis in the geosciences has been demonstrated in an ever increasing number of cases. While in most applications the method can be considered as derivative or as an extension of electron microprobe methodology, features unique to the proton microprobe enable new approaches to hitherto intractable problems of analysis. An appropriate niche has been established in igneous mineralogy and petrology, with important implications both in the basic geosciences as well as mineral industry applications, particularly in the diamond exploration industry. This paper reviews recent advances and discusses the advantages and limitations of current micro-PIXE applications in the geosciences in view of other competing and complimentary methods

The complete amino acid sequence of the antenna polypeptide B806-866-β from the cytoplasmic membrane of the green bacterium Chloroflexus auranliacus

AbstractThe bacteriochlorophyll a-binding polypeptide B806–866-β was extracted from membranes of the green thermophilic bacterium Chloroflexus aurantiacus with chloroform/methanol/ammonium acetate. Purification of the antenna polypeptide (6.3 kDa) was achieved by chromatography on Sephadex LH-60, Whatman DE-32 and by FPLC. The complete amino acid sequence (53 amino acid residues) was determined. The B806–866-β polypeptide is sequence homologous to the antenna β-polypeptides of purple bacteria (27–40%) and exhibits the characteristic three domain structure of the B870, B800–850 and B800–820 antenna complexes. The two typical His residues, conserved in all antenna β-polypeptides of purple bacteria, were found: His-24 lies within the N-terminal hydrophilic domain and His-42 within the central hydrophobic domain. This polypeptide together with the previously described α-polypeptide form the basic structural unit of the B806–866 antenna complex from C. aurantiacus

Understanding the μ\muSR spectra of MnSi without magnetic polarons

Transverse-field muon-spin rotation ($\mu$SR) experiments were performed on a single crystal sample of the non-centrosymmetric system MnSi. The observed angular dependence of the muon precession frequencies matches perfectly the one of the Mn-dipolar fields acting on the muons stopping at a 4a position of the crystallographic structure. The data provide a precise determination of the magnetic dipolar tensor. In addition, we have calculated the shape of the field distribution expected below the magnetic transition temperature $T_C$ at the 4a muon-site when no external magnetic field is applied. We show that this field distribution is consistent with the one reported by zero-field $\mu$SR studies. Finally, we present ab initio calculations based on the density-functional theory which confirm the position of the muon stopping site inferred from transverse-field $\mu$SR. In view of the presented evidence we conclude that the $\mu$SR response of MnSi can be perfectly and fully understood without invoking a hypothetical magnetic polaron state.Comment: 10 pages, 12 figure

Design of a Personalized Lighting Control System Enabled by a Space Model

This paper reports on a research effort to develop a prototype of a personalized lighting control system that adjusts the visual environment based on user preferences. Lighting controllers query a space model to retrieve lighting objects that are near given user locations and map user preferences into control actions for these lighting objects. A user scenario illustrates the concept of personalized lighting control. The scenario is used to develop functional and non-functional system requirements which inform system design. The structure of a proposed space model and space model queries are described and illustrated with examples. Implementation environments for system modules and data communication between modules are discussed. System and user tests are outlined that will be performed for initial feedback on the feasibility of personalized lighting control

Cardiovascular toxicity induced by chemotherapy, targeted agents and radiotherapy: ESMO Clinical Practice Guidelines

Cardiovascular (CV) toxicity is a potential short- or long-term complication of various anticancer therapies. Some drugs, such as anthracyclines or other biological agents, have been implicated in causing potentially irreversible clinically important cardiac dysfunction. Although targeted therapies are considered less toxic and better tolerated by patients compared with classic chemotherapy agents, rare but serious complications have been described, and longer follow-up is needed to determine the exact profile and outcomes of related cardiac side-effects. Some of these side-effects are irreversible, leading to progressive CV disease, and some others induce reversible dysfunction with no long-term cardiac damage to the patient. Assessment of the prevalence, type and severity of cardiac toxicity caused by various cancer treatments is a breakthrough topic for patient management. Guidelines for preventing, monitoring and treating cardiac side-effects are a major medical need. Efforts are needed to promote strategies for cardiac risk prevention, detection and management, avoiding unintended consequences that can impede development, regulatory approval and patient access to novel therapy. These new ESMO Clinical Practice Guidelines are the result of a multidisciplinary cardio-oncology review of current evidence with the ultimate goal of providing strict criteria-based recommendations on CV risk prevention, assessment, monitoring and management during anticancer treatmen

Dynamical fidelity of a solid-state quantum computation

In this paper we analyze the dynamics in a spin-model of quantum computer. Main attention is paid to the dynamical fidelity (associated with dynamical errors) of an algorithm that allows to create an entangled state for remote qubits. We show that in the regime of selective resonant excitations of qubits there is no any danger of quantum chaos. Moreover, in this regime a modified perturbation theory gives an adequate description of the dynamics of the system. Our approach allows to explicitly describe all peculiarities of the evolution of the system under time-dependent pulses corresponding to a quantum protocol. Specifically, we analyze, both analytically and numerically, how the fidelity decreases in dependence on the model parameters.Comment: 9 pages, 6 figures, submitted to PR

Magnetism, superconductivity and coupling in cuprate heterostructures probed by low-energy muon-spin rotation

We present a low-energy muon-spin-rotation study of the magnetic and superconducting properties of YBa2Cu3O7/PrBa2Cu3O7 trilayer and bilayer heterostructures. By determining the magnetic-field profiles throughout these structures we show that a finite superfluid density can be induced in otherwise semiconducting PrBa2Cu3O7 layers when juxtaposed to YBa2Cu3O7 "electrodes" while the intrinsic antiferromagnetic order is unaffected.Comment: 10 pages, 9 figures; figure 9 corrected in version

Interlaboratory evaluation of rat hepatic gene expression changes induced by methapyrilene.

Several studies using microarrays have shown that changes in gene expression provide information about the mechanism of toxicity induced by xenobiotic agents. Nevertheless, the issue of whether gene expression profiles are reproducible across different laboratories remains to be determined. To address this question, several members of the Hepatotoxicity Working Group of the International Life Sciences Institute Health and Environmental Sciences Institute evaluated the liver gene expression profiles of rats treated with methapyrilene (MP). Animals were treated at one facility, and RNA was distributed to five different sites for gene expression analysis. A preliminary evaluation of the number of modulated genes uncovered striking differences between the five different sites. However, additional data analysis demonstrated that these differences had an effect on the absolute gene expression results but not on the outcome of the study. For all users, unsupervised algorithms showed that gene expression allows the distinction of the high dose of MP from controls and low dose. In addition, the use of a supervised analysis method (support vector machines) made it possible to correctly classify samples. In conclusion, the results show that, despite some variability, robust gene expression changes were consistent between sites. In addition, key expression changes related to the mechanism of MP-induced hepatotoxicity were identified. These results provide critical information regarding the consistency of microarray results across different laboratories and shed light on the strengths and limitations of expression profiling in drug safety analysis