BCI-Based Navigation in Virtual and Real Environments

A Brain-Computer Interface (BCI) is a system that enables people to control an external device with their brain activity, without the need of any muscular activity. Researchers in the BCI field aim to develop applications to improve the quality of life of severely disabled patients, for whom a BCI can be a useful channel for interaction with their environment. Some of these systems are intended to control a mobile device (e. g. a wheelchair). Virtual Reality is a powerful tool that can provide the subjects with an opportunity to train and to test different applications in a safe environment. This technical review will focus on systems aimed at navigation, both in virtual and real environments.This work was partially supported by the Innovation, Science and Enterprise Council of the Junta de Andalucía (Spain), project P07-TIC-03310, the Spanish Ministry of Science and Innovation, project TEC 2011-26395 and by the European fund ERDF

Ribavirin as a First Treatment Approach for Hepatitis E Virus Infection in Transplant Recipient Patients

The hepatitis E virus (HEV) is the major cause of acute hepatitis of viral origin worldwide. Despite its usual course as an asymptomatic self-limited hepatitis, there are highly susceptible populations, such as those with underlying immunosuppression, which could develop chronic hepatitis. In this situation, implementation of therapy is mandatory in the sense to facilitate viral clearance. Currently, there are no specific drugs approved for HEV infection, but ribavirin (RBV), the drug of choice, is used for off-label treatment. Here, we present two cases of chronic HEV infection in transplant patients, reviewing and discussing the therapeutic approach available in the literature. The use of RBV for the treatment of an HEV infection in organ transplant patients seems to be effective. The recommendation of 12 weeks of therapy is adequate in terms of efficacy. Nevertheless, there are important issues that urgently need to be assessed, such as optimal duration of therapy and drug dosage

The decay Z -> neutrino antineutrino photon in the Standard Model

A complete study of the one-loop induced decay Z -> neutrino antineutrino photon is presented within the framework of the Standard Model. The advantages of using a nonlinear gauge are stressed. We have found that the main contributions come from the electric dipole and the magnetic dipole transitions of the Z gauge boson and the neutrino, respectively. We obtain a branching ratio B=7.16E-10, which is about four orders of magnitude smaller than the bound recentely obtained by the L3 collaboration and thus it leaves open a window to search for new physics effects in single-photon decays of the Z boson.Comment: REVTEX,15 pp, 5 eps figures, Approved for publication in Physical Review

Coherent Pair Production by Photons in the 20-170 GeV Energy Range Incident on Crystals and Birefringence

The cross section for coherent pair production by linearly polarised photons in the 20-170 GeV energy range was measured for photon aligned incidence on ultra-high quality diamond and germanium crystals. The theoretical description of coherent bremsstrahlung and coherent pair production phenomena is an area of active theoretical debate and development. However, under our experimental conditions, the theory predicted the combined cross section and polarisation experimental observables very well indeed. In macroscopic terms, our experiment measured a birefringence effect in pair production in a crystal. This study of this effect also constituted a measurement of the energy dependent linear polarisation of photons produced by coherent bremsstrahlung in aligned crystals. New technologies for manipulating high energy photon beams can be realised based on an improved understanding of QED phenomena at these energies. In particular, this experiment demonstrates an efficient new polarimetry technique. The pair production measurements were done using two independent methods simultaneously. The more complex method using a magnet spectrometer showed that the simpler method using a multiplicity detector was also viable.Comment: 10 pages, 13 figures, 1 table, REVTeX4 two column, Version for publicatio

Linear to Circular Polarisation Conversion using Birefringent Properties of Aligned Crystals for Multi-GeV Photons

We present the first experimental results on the use of a thick aligned Si crystal acting as a quarter wave plate to induce a degree of circular polarisation in a high energy linearly polarised photon beam. The linearly polarised photon beam is produced from coherent bremsstrahlung radiation by 178 GeV unpolarised electrons incident on an aligned Si crystal, acting as a radiator. The linear polarisation of the photon beam is characterised by measuring the asymmetry in electron-positron pair production in a Ge crystal, for different crystal orientations. The Ge crystal therefore acts as an analyser. The birefringence phenomenon, which converts the linear polarisation to circular polarisation, is observed by letting the linearly polarised photons beam pass through a thick Si quarter wave plate crystal, and then measuring the asymmetry in electron-positron pair production again for a selection of relative angles between the crystallographic planes of the radiator, analyser and quarter wave plate. The systematics of the difference between the measured asymmetries with and without the quarter wave plate are predicted by theory to reveal an evolution in the Stokes parameters from which the appearance of a circularly polarised component in the photon beam can be demonstrated. The measured magnitude of the circularly polarised component was consistent with the theoretical predictions, and therefore is in indication of the existence of the birefringence effect.Comment: 12 pages, 12 figures, 1 table, REVTeX4 two column, Version for publicatio

Results on the Coherent Interaction of High Energy Electrons and Photons in Oriented Single Crystals

The CERN-NA-59 experiment examined a wide range of electromagnetic processes for multi-GeV electrons and photons interacting with oriented single crystals. The various types of crystals and their orientations were used for producing photon beams and for converting and measuring their polarisation. The radiation emitted by 178 GeV unpolarised electrons incident on a 1.5 cm thick Si crystal oriented in the Coherent Bremsstrahlung (CB) and the String-of-Strings (SOS) modes was used to obtain multi-GeV linearly polarised photon beams. A new crystal polarimetry technique was established for measuring the linear polarisation of the photon beam. The polarimeter is based on the dependence of the Coherent Pair Production (CPP) cross section in oriented single crystals on the direction of the photon polarisation with respect to the crystal plane. Both a 1 mm thick single crystal of Germanium and a 4 mm thick multi-tile set of synthetic Diamond crystals were used as analyzers of the linear polarisation. A birefringence phenomenon, the conversion of the linear polarisation of the photon beam into circular polarisation, was observed. This was achieved by letting the linearly polarised photon beam pass through a 10 cm thick Silicon single crystal that acted as a "quarter wave plate" (QWP) as suggested by N. Cabibbo et al.Comment: Presented at International workshop "Relativistic Channeling and Related Coherent Phenomena", Frascati (Rome) 23-26 March 200

Coherent bremsstrahlung, boherent pair production, birefringence and polarimetry in the 20-170 GeV energy range using aligned crystals

The processes of coherent bremsstrahlung (CB) and coherent pair production (CPP) based on aligned crystal targets have been studied in the energy range 20-170 GeV. The experimental arrangement allowed for measurements of single photon properties of these phenomena including their polarization dependences. This is significant as the theoretical description of CB and CPP is an area of active theoretical debate and development. With the theoretical approach used in this paper both the measured cross sections and polarization observables are predicted very well. This indicates a proper understanding of CB and CPP up to energies of 170 GeV. Birefringence in CPP on aligned crystals is applied to determine the polarization parameters in our measurements. New technologies for high energy photon beam optics including phase plates and polarimeters for linear and circular polarization are demonstrated in this experiment. Coherent bremsstrahlung for the strings-on-strings (SOS) orientation yields a larger enhancement for hard photons than CB for the channeling orientations of the crystal. Our measurements and our calculations indicate low photon polarizations for the high energy SOS photons.Comment: 23 pages, 27 figures, 2 tables, REVTeX4 two column

Quantification of inaccurate diagnosis of COPD in primary care medicine: An analysis of the COACH clinical audit

Background: Inaccurate diagnosis in COPD is a current problem with relevant consequences in terms of inefficient health care, which has not been thoroughly studied in primary care medicine. The aim of the present study was to evaluate the degree of inaccurate diagnosis in Primary Care in Spain and study the determinants associated with it. Methods: The Community Assessment of COPD Health Care (COACH) study is a national, observational, randomized, non-interventional, national clinical audit aimed at evaluating clinical practice for patients with COPD in primary care medicine in Spain. For the present analysis, a correct diagnosis was evaluated based on previous exposure and airway obstruction with and without the presence of symptoms. The association of patient-level and center-level variables with inaccurate diagnosis was studied using multivariate multilevel binomial logistic regression models. Results: During the study 4,307 cases from 63 centers were audited. The rate of inaccurate diagnosis was 82.4% (inter-regional range from 76.8% to 90.2%). Patient-related interventions associated with inaccurate diagnosis were related to active smoking, lung function evaluation, and specific therapeutic interventions. Center-level variables related to the availability of certain complementary tests and different aspects of the resources available were also associated with an inaccurate diagnosis. Conclusions: The prevalence data for the inaccurate diagnosis of COPD in primary care medicine in Spain establishes a point of reference in the clinical management of COPD. The descriptors of the variables associated with this inaccurate diagnosis can be used to identify cases and centers in which inaccurate diagnosis is occurring considerably, thus allowing for improvement

Very light CP-odd scalar in the Two-Higgs-Doublet Model

We show that a general two-Higgs-doublet model (THDM) with a very light CP-odd scalar (A) can be compatible with the rho parameter, Br(b --> s\gamma), R_b, A_b, (g-2) of muon, Br(Upsilon --> A gamma), and the direct search via the Yukawa process at LEP. For its mass around 0.2 GeV, the muon (g-2) and Br(Upsilon --> A \gamma) data require tan(beta) to be about 1. Consequently, A can behave like a fermiophobic CP-odd scalar and predominantly decay into a photon pair ("gamma gamma"), which registers in detectors of high energy collider experiments as a single photon signature when the momentum of A is large. We compute the partial decay width of Z --> A A A and the production rate of f \bar{f} --> Z A A --> Z +"gamma gamma", f^' {\bar f} --> W^{\pm} A A --> W^\pm + "gamma gamma" and f \bar f --> H^+ H^- --> W^+ W^- A A --> W^+ W^- + "gamma gamma" at high energy colliders such as LEP, Tevatron, LHC, and future Linear Colliders. Other production mechanisms of a light A, such as gg --> h --> AA --> "gamma gamma", are also discussed.Comment: Some improvementes, references updated, 3 new figures, one new appendix, abstract and conclusions unchaged. Version to appear in Physical Review

GNSS 3D displacement field determination in Lorca (Murcia, Spain) subsidence area

Trabajo presentado en el AGU (American Geophysical Union) Fall Meeting: Advancing Earth and Space Science, celebrado en San Francisco (Estados Unidos), del 12 al 16 de diciembre de 2016Land subsidence associated to the overexploitation of aquifers represents a common hazard impacting extensive areas worldwide. Recently, González and Fernández (20101) revealed that the Alto Guadalentín Basin, located in southern Spain, is affected by the highest subsidence rates measured in Europe (about 10 cm/yr) as a direct consequence of long-term aquifer exploitation. They used ERS and ENVISAT radar data spanning the 1992¿2007 period. They identify a delayed transient nonlinear compaction of the Alto Guadalentín aquifer due to the 1990¿1995 drought period. Bonì et al. (2015) extend the previous studies using advanced DInSAR techniques to process ALOS PALSAR (2007¿2010) and COSMO-SkyMed (2011¿2012) radar images. The combination of multi-sensor SAR images with different resolutions allows for a wider monitoring time span of 20 years (1992¿2012) over the Alto Guadalentín Basin. All regional studies of the area to date are based on satellite radar interferometry using just ascending or descending acquisitions, without any combination among them to obtain vertical and horizontal (E-W) components. It is important to obtain the 3D motion field in order to perform a correct interpretation of the observations, as well as an advanced model of the aquifer evolution, to be consider for sustainable management plans of groundwater resources and hazard assessments. With this objective, a GNSS network has been defined and two surveys have been carried out in November 2015 and July 2016. Despite the limited time interval covered by the surveys, the results allow us to obtain, for the first time, the regional 3D displacement field associated to the exploitation of the aquifer. These results, although in a preliminary form, confirm previous observations and suggest that the ad-hoc establishment of small GNSS networks represent a valuable technique for the spatio-temporal monitoring of the 3D displacement field of areas subjected to extensive groundwater extraction.Peer reviewe