High Efficiency Positron Accumulation for High-Precision Measurements

Positrons are accumulated within a Penning trap designed to make more precise measurements of the positron and electron magnetic moments. The retractable radioactive source used is weak enough to require no license for handling radioactive material and the radiation dosage one meter from the source gives an exposure several times smaller than the average radiation dose on the earth's surface. The 100 mK trap is mechanically aligned with the 4.2 K superconducting solenoid that produces a 6 tesla magnetic trapping field with a direct mechanical coupling.Comment: 7 pages, 9 figure

Mapping surgical coordinates of the sphenopalatine foramen : surgical navigation study

Aims to identify measurements that may help intra operative localisation of the sphenopalatine foramen. The study used three dimensional surgical navigation software to study radiological anatomy, in order to define the distances and angulations between identifiable bony landmarks and the sphenopalatine foramen. The distance from the anterior nasal spine to the sphenopalatine foramen was 59 mm (+4 mm; inter observer variation = 0.866; intra observer variation = 0.822). The distance from the piriform aperture to the sphenopalatine foramen was 48 mm (+4 mm; inter observer variation = 0.828; intra observer variation = 0.779). The angle of elevation from the nasal floor to the sphenopalatine foramen was 22 degrees (+3 degrees; inter observer variation = 0.441; intra observer variation = 0.499). The sphenopalatine foramen is consistently identifiable on three dimensional, reconstructed computed tomography scans. Repeatable measurements were obtained. The centre point of the foramen lies 59 mm from the anterior nasal spine at 22 degrees elevation above the plane of the hard palate and 48 mm from the piriform aperture. We discuss how these data could be used to facilitate intra operative location of the sphenopalatine foramen in difficult cases

Constraints on Hidden Photon Models from Electron g-2 and Hydrogen Spectroscopy

The hidden photon model is one of the simplest models which can explain the anomaly of the muon anomalous magnetic moment (g-2). The experimental constraints are studied in detail, which come from the electron g-2 and the hydrogen transition frequencies. The input parameters are set carefully in order to take dark photon contributions into account and to prevent the analysis from being self-inconsistent. It is shown that the new analysis provides a constraint severer by more than one order of magnitude than the previous result.Comment: 18 pages, 2 figures, 1 table. v2: minor correction

On the \phi(1020)f_0(980) S-wave scattering and the Y(2175) resonance

We have studied the \phi(1020)f_0(980) S-wave scattering at energies around threshold employing chiral Lagrangians coupled to vector mesons through minimal coupling. The interaction kernel is obtained by considering the f_0(980) as a K\bar{K} bound state. The Y(2175) resonance is generated in this approach by the self-interactions between the \phi(1020) and the f_0(980) resonances. We are able to describe the e^+e^-\to \phi(1020)f_0(980) recent scattering data to test experimentally our scattering amplitudes, concluding that the Y(2175) resonance has a large \phi(1020)f_0(980) meson-meson component.Comment: 20 pages, 8 figure

Inner ear ossification and mineralization kinetics in human embryonic development - microtomographic and histomorphological study.

Little is known about middle and inner ear development during the second and third parts of human fetal life. Using ultra-high resolution Microcomputed Tomography coupled with bone histology, we performed the first quantitative middle and inner ear ossification/mineralization evaluation of fetuses between 17 and 39 weeks of gestational age. We show distinct ossification paces between ossicles, with a belated development of the stapes. A complete cochlear bony covering is observed within the time-frame of the onset of hearing, whereas distinct time courses of ossification for semicircular canal envelopes are observed in relation to the start of vestibular functions. The study evidences a spatio-temporal relationship between middle and inner ear structure development and the onset of hearing and balance, critical senses for the fetal adaptation to birth

Mathematical modeling to optimize control strategies in an industrial biotrickling filter for biogas sweetening

Burning biogas in a combined heat and power (CHP) plant is a promising option to reduce the emissions and the operational cost of a WWTP. However, the biogas generated in anaerobic digestion facilities in WWTPs contains average concentrations of H2S in the range from 0.1 to 0.5 vol.% which has to be removed to avoid corrosion, unnecessary production of by-products, and SO2 emissions. In a biotrickling filter (BTF), the H2S is absorbed and removed in a packed column where biomass is immobilized, being a liquid phase continuously recirculated from the bottom of the reactor. Advances in mathematical modelling of biofilters have allowed improving the knowledge of the phenomena and interactions involved in the biological desulfurization of biogas (Almenglo et al. 2013). The principal limitation for the long term operation of BTF in biogas sweetening is the accumulation of elemental sulphur due to oxygen mass transfer limitations. Apart from reducing the removal efficiency, this accumulation increases pressure drops, thus it increases the operation cost to blow the air through the bed, and force frequent maintenance tasks to replace or wash the packing material. In the present study, the dynamic model developed and validated by Rodriguez (2013) has been used to evaluate different control strategies and optimize the performance of a BTF located in the WWTP of Manresa (Barcelona). Particularly, the use of different kind of packing materials (organic and inorganic) has been evaluated to determine in different operation conditions which removal efficiency (RE) and sulphur accumulation could be expected, i.e time period of operation before the forced shutdown. Additionally, an optimal distribution of different particle sizes of materials has been proposed to reduce sulphur rate production, affecting minimally the abatement efficiencies currently obtained.Peer ReviewedPostprint (published version

Novel Approaches towards Highly Selective Self-Powered Gas Sensors

The prevailing design approaches of semiconductor gas sensors struggle to overcome most of their current limitations such as poor selectivity, and high power consumption. Herein, a new sensing concept based on devices that are capable of detecting gases without the need of any external power sources required to activate interaction of gases with sensor or to generate the sensor read out signal. Based on the integration of complementary functionalities (namely; powering and sensing) in a singular nanostructure, self-sustained gas sensors will be demonstrated. Moreover, a rational methodology to design organic surface functionalization that provide high selectivity towards single gas species will also be discussed. Specifically, theoretical results, confirmed experimentally, indicate that precisely tuning of the sterical and electronic structure of sensor material/organic interfaces can lead to unprecedented selectivity values, comparable to those typical of bioselective processes. Finally, an integrated gas sensor that combine both the self-powering and selective detection strategies in one single device will also be presented. © 2015 Published by Elsevier Ltd.Peer ReviewedPostprint (published version

Field enhanced bulk conductivity of acceptor-doped BaTi1−xCaxO3−x ceramics

The electrical properties of Ca-doped BaTiO3 are very different when Ca substitutes onto Ba or Ti sites. The p-type semiconductivity of Ti-substituted ceramics increases reversibly by one to two orders of magnitude under a dc-bias voltage of 100 V cm−1, whereas Ba-substituted ceramics show little sensitivity to a dc bias. This increase in BaTi1−xCaxO3−x, studied over the temperature range 150–600 °C, is independent of electrode material and atmosphere and is attributed to ionization of underbonded O2− ions adjacent to acceptor-doped Ca2+ ions

Rare Kaon Decays in the 1/Nc1/N_c-Expansion

We study the unknown coupling constants that appear at order $p^4$ in the Chiral Perturbation Theory analysis of $K \to \pi \gamma^* \to \pi l^+ l^-$, $K^{+-} \to \pi^{+-} \gamma \gamma$ and $K \to \pi \pi \gamma$ decays. To that end, we compute the chiral realization of the $\Delta S \, = \, 1$ Hamiltonian in the framework of the $1/N_c$-expansion of the low-energy action. The phenomenological implications are also discussed.Comment: 18 pages, LaTeX, CPT-92/P.279

Exploring the relative value of end of life QALYs: are the comparators important?

In the UK, life extending, end-of-life (EoL) treatments are an exception to standard cost-per-quality-adjusted life year (QALY) thresholds. This implies that greater value is placed on gaining these QALYs, than QALYs gained by the majority of other patient groups treated for anything else in the health system, even for other EoL contexts (such as quality of life (QoL) improvements alone). This paper reports a Person Trade-Off (PTO) study to test whether studies that find societal support for prioritising EoL life extensions can be explained by the severity, in terms of prospective QALYs loss, of the non-terminal comparator scenarios. Eight health scenarios were designed depicting i) QoL improvements for non-EoL temporary (T-QoL) and chronic (C-QoL) health problems and ii) QoL improvements and life extensions (LEs) for EoL health problems. Preferences were elicited from a quota sample of 901 Scottish respondents in 2016 using PTO techniques via Computer Assisted Personal Interview (CAPI). Our results indicate that there is little evidence to suggest that the severity of non-EoL comparator scenarios influence preferences for EoL treatments. Respondents do not appear to have a preference for EoL over non-EoL health gains; instead there is some indication that non-EoL health gains are preferred, particularly when compared to EoL-LE health gains. Comparing between QoL and life extending EoL scenarios, our results suggest QoL improvements are preferred to life extensions. Overall, results challenge current UK EoL policy which gives additional weight to EoL health gains, particularly EoL life extensions in the case of the National Institute for Health and Care Excellence (NICE)