Instrumental neutron activation analysis of an enriched 28Si single-crystal

The determination of the Avogadro constant plays a key role in the redefinition of the kilogram in terms of a fundamental constant. The present experiment makes use of a silicon single-crystal highly enriched in 28Si that must have a total impurity mass fraction smaller than a few parts in 109. To verify this requirement, we previously developed a relative analytical method based on neutron activation for the elemental characterization of a sample of the precursor natural silicon crystal WASO 04. The method is now extended to fifty-nine elements and applied to a monoisotopic 28Si single-crystal that was grown to test the achievable enrichment. Since this crystal was likely contaminated, this measurement tested also the detection capabilities of the analysis. The results quantified contaminations by Ge, Ga, As, Tm, Lu, Ta, W and Ir and, for a number of the detectable elements, demonstrated that we can already reach the targeted 1 ng/g detection limit.Comment: 9 pages, 1 figure, 1 tabl

Early Science with the Large Millimetre Telescope: Molecules in the Extreme Outflow of a proto-Planetary Nebula

Extremely high velocity emission likely related to jets is known to occur in some proto-Planetary Nebulae. However, the molecular complexity of this kinematic component is largely unknown. We observed the known extreme outflow from the proto-Planetary Nebula IRAS 16342-3814, a prototype water fountain, in the full frequency range from 73 to 111 GHz with the RSR receiver on the Large Millimetre Telescope. We detected the molecules SiO, HCN, SO, and $^{13}$CO. All molecular transitions, with the exception of the latter are detected for the first time in this source, and all present emission with velocities up to a few hundred km s$^{-1}$. IRAS 16342-3814 is therefore the only source of this kind presenting extreme outflow activity simultaneously in all these molecules, with SO and SiO emission showing the highest velocities found of these species in proto-Planetary Nebulae. To be confirmed is a tentative weak SO component with a FWHM $\sim$ 700 km s$^{-1}$. The extreme outflow gas consists of dense gas (n$_{\rm H_2} >$ 10$^{4.8}$--10$^{5.7}$ cm$^{-3}$), with a mass larger than $\sim$ 0.02--0.15 M$_{\odot}$. The relatively high abundances of SiO and SO may be an indication of an oxygen-rich extreme high velocity gas.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical Society Letter

Palatal surgery in a transoral robotic setting (TORS): preliminary results of a retrospective comparison between uvulopalatopharyngoplasty (UPPP), expansion sphincter pharyngoplasty (ESP) and barbed repositioning pharyngoplasty (BRP)

Negli ultimi anni si è diffusa lopinione che la chirurgia multilivello nel trattamento della sindrome delle apnee ostruttive garantisca risultati pià soddisfacenti. Lobiettivo del nostro lavoro è quello di confrontare tre tecniche palatali associate alla TORS: luvulopalatofaringoplastica (UPPP), lexpansion sphincter pharyngoplasy (ESP) e la barbed repositioning pharingoplasty (BRP). Trenta pazienti, trattati con TORS, tonsillectomia e settoturbinoplastica e chirurgia palatale sono stati retrospettivamente studiati. I seguenti valori pre e post-operatori sono stati presi in considerazione: AHI, ESS, VAS per la valutazione del dolore, tempi operatori palatali, data di dimissione e complicanze (tipi ed incidenza). Sia la BRP che lESP hanno garantito dei valori postoperatorio di AHI inferiori rispetto allUPPP con un maggior tasso di successo chirurgico. Dallaltra parte non è stato possibile dimostrare una superiorità della BRP sullESP. I tempi operatori più lunghi sono stati registrati nel gruppo ESP mentre i più brevi sono stati riscontrati nel gruppo BRP. Riassumendo, ESP e BRP sono risultate più efficaci dellUPPP in un setting robotico multilivello. Inoltre, essendo una tecnica rapida, di facile apprendimento e dal basso tasso di complicanze, la BRP si presenta come una valida opzione chirurgica nel trattamento dellOSAS

LMT/AzTEC observations of Vega

Vega is the prototypical debris disc system. Its architecture has been extensively studied at optical to millimetre wavelengths, revealing a near face-on, broad, and smooth disc with multiple distinct components. Recent millimetre-wavelength observations from ALMA spatially resolved the inner edge of the outer, cold planetesimal belt from the star for the first time. Here we present early science imaging observations of the Vega system with the AzTEC instrument on the 32-m LMT, tracing extended emission from the disc out to 150 au from the star. We compare the observations to three models of the planetesimal belt architecture to better determine the profile of the outer belt. A comparison of these potential architectures for the disc does not significantly differentiate between them with the modelling results being similar in many respects to the previous ALMA analysis, but differing in the slope of the outer region of the disc. The measured flux densities are consistent between the LMT (single dish) and ALMA (interferometric) observations after accounting for the differences in wavelength of observation. The LMT observations suggest the outer slope of the planetesimal belt is steeper than was suggested in the ALMA analysis. This would be consistent with the interferometric observations being mostly blind to structure at the disc outer edges, but the overall low signal to noise of the LMT observations does not definitively resolve the structure of the outer planetesimal belt.FK and JPM acknowledge research support by the Ministry of Science and Technology of Taiwan under grant MOST107-2119-M-001-031-MY3, and Academia Sinica under grant AS-IA-106-M03. JPM acknowledges research support by the Ministry of Science and Technology of Taiwan under grant MOST109-2112-M-001-036-MY3. MC thanks Consejo Nacional de Ciencia y Tecnología (CONACyT) for financial support through grant CB-2015-256961

Search for galactic axions with a high-Q dielectric cavity

A haloscope of the QUAX--$a\gamma$ experiment, composed of an high-Q resonant cavity immersed in a 8 T magnet and cooled to $\sim 4.5$~K is operated to search for galactic axion with mass $m_a\simeq42.8~\mu\text{eV}$. The design of the cavity with hollow dielectric cylinders concentrically inserted in a OFHC Cu cavity, allowed us to maintain a loaded quality-factor Q $\sim 300000$ during the measurements in presence of magnetic field. Through the cavity tuning mechanism it was possible to modulate the resonance frequency of the haloscope in the region $10.35337-10.35345$~GHz and thus acquire different dataset at different resonance frequencies. Acquiring each dataset for about 50 minutes, combining them and correcting for the axion's signal estimation-efficiency we set a limit on the axion-photon coupling $g_{a\gamma\gamma}< 0.731\times10^{-13}$ GeV$^{-1}$ with the confidence level set at $90\%$

The NIKA2 large-field-of-view millimetre continuum camera for the 30 m IRAM telescope

Context. Millimetre-wave continuum astronomy is today an indispensable tool for both general astrophysics studies (e.g. star formation, nearby galaxies) and cosmology (e.g. cosmic microwave background and high-redshift galaxies). General purpose, large-field-of-view instruments are needed to map the sky at intermediate angular scales not accessible by the high-resolution interferometers (e.g. ALMA in Chile, NOEMA in the French Alps) and by the coarse angular resolution space-borne or ground-based surveys (e.g. Planck, ACT, SPT). These instruments have to be installed at the focal plane of the largest single-dish telescopes, which are placed at high altitude on selected dry observing sites. In this context, we have constructed and deployed a three-thousand-pixel dual-band (150 GHz and 260 GHz, respectively 2 mm and 1.15 mm wavelengths) camera to image an instantaneous circular field-of-view of 6.5 arcmin in diameter, and configurable to map the linear polarisation at 260 GHz. Aims. First, we are providing a detailed description of this instrument, named NIKA2 (New IRAM KID Arrays 2), in particular focussing on the cryogenics, optics, focal plane arrays based on Kinetic Inductance Detectors, and the readout electronics. The focal planes and part of the optics are cooled down to the nominal 150 mK operating temperature by means of an adhoc dilution refrigerator. Secondly, we are presenting the performance measured on the sky during the commissioning runs that took place between October 2015 and April 2017 at the 30-m IRAM telescope at Pico Veleta, near Granada (Spain). Methods. We have targeted a number of astronomical sources. Starting from beam-maps on primary and secondary calibrators we have then gone to extended sources and faint objects. Both internal (electronic) and on-the-sky calibrations are applied. The general methods are described in the present paper. Results. NIKA2 has been successfully deployed and commissioned, performing in-line with expectations. In particular, NIKA2 exhibits full width at half maximum angular resolutions of around 11 and 17.5 arcsec at respectively 260 and 150 GHz. The noise equivalent flux densities are, at these two respective frequencies, 33±2 and 8±1 mJy s1/2. A first successful science verification run was achieved in April 2017. The instrument is currently offered to the astronomy community and will remain available for at least the following ten years

Defining the genetic control of human blood plasma N-glycome using genome-wide association study

Glycosylation is a common post-translational modification of proteins. Glycosylation is associated with a number of human diseases. Defining genetic factors altering glycosylation may provide a basis for novel approaches to diagnostic and pharmaceutical applications. Here we report a genome-wide association study of the human blood plasma N-glycome composition in up to 3811 people measured by Ultra Performance Liquid Chromatography (UPLC) technology. Starting with the 36 original traits measured by UPLC, we computed an additional 77 derived traits leading to a total of 113 glycan traits. We studied associations between these traits and genetic polymorphisms located on human autosomes. We discovered and replicated 12 loci. This allowed us to demonstrate an overlap in genetic control between total plasma protein and IgG glycosylation. The majority of revealed loci contained genes that encode enzymes directly involved in glycosylation (FUT3/FUT6, FUT8, B3GAT1, ST6GAL1, B4GALT1, ST3GAL4, MGAT3 and MGAT5) and a known regulator of plasma protein fucosylation (HNF1A). However, we also found loci that could possibly reflect other more complex aspects of glycosylation process. Functional genomic annotation suggested the role of several genes including DERL3, CHCHD10, TMEM121, IGH and IKZF1. The hypotheses we generated may serve as a starting point for further functional studies in this research area

Replication of fifteen loci involved in human plasma protein N-glycosylation in 4,802 samples from four cohorts

Human protein glycosylation is a complex process, and its in vivo regulation is poorly understood. Changes in glycosylation patterns are associated with many human diseases and conditions. Understanding the biological determinants of protein glycome provides a basis for future diagnostic and therapeutic applications. Genome-wide association studies (GWAS) allow to study biology via a hypothesis-free search of loci and genetic variants associated with a trait of interest. Sixteen loci were identified by three previous GWAS of human plasma proteome N-glycosylation. However, the possibility that some of these loci are false positives needs to be eliminated by replication studies, which have been limited so far. Here, we use the largest set of samples so far (4,802 individuals) to replicate the previously identified loci. For all but one locus, the expected replication power exceeded 95%. Of the sixteen loci reported previously, fifteen were replicated in our study. For the remaining locus (near the KREMEN1 gene) the replication power was low, and hence replication results were inconclusive. The very high replication rate highlights the general robustness of the GWAS findings as well as the high standards adopted by the community that studies genetic regulation of protein glycosylation. The fifteen replicated loci present a good target for further functional studies. Among these, eight genes encode glycosyltransferases: MGAT5, B3GAT1, FUT8, FUT6, ST6GAL1, B4GALT1, ST3GAL4, and MGAT3. The remaining seven loci offer starting points for further functional follow-up investigation into molecules and mechanisms that regulate human protein N-glycosylation in vivo

Early science with the Large Millimetre Telescope: Deep LMT/AzTEC millimetre observations of ϵ Eridani and its surroundings

ϵ Eridani is a nearby, young Sun-like star that hosts a ring of cool debris analogous to the Solar system's Edgeworth-Kuiper belt. Early observations at (sub-)mm wavelengths gave tentative evidence of the presence of inhomogeneities in the ring, which have been ascribed to the effect of a putative low eccentricity planet, orbiting close to the ring. The existence of these structures has been recently challenged by high-resolution interferometric millimetre observations. Here, we present the deepest single-dish image of ϵ Eridani at millimetre wavelengths, obtained with the Large Millimetre Telescope Alfonso Serrano (LMT). The main goal of these LMT observations is to confirm (or refute) the presence of non-axisymmetric structure in the disc. The dusty ring is detected for the first time along its full projected elliptical shape. The radial extent of the ring is not spatially resolved and shows no evidence, to within the uncertainties, of dust density enhancements. Additional features of the 1.1 mm map are: (i) the presence of significant flux in the gap between the ring and the star, probably providing the first exo-solar evidence of Poynting-Robertson drag, (ii) an unambiguous detection of emission at the stellar positionwith a flux significantly above that expected from ϵ Eridani's photosphere, and (iii) the identification of numerous unresolved sources which could correspond to background dusty star-forming galaxies.This work would have not been possible without the long-term financial support from the Mexican Science and Technology Funding Agency, CONACyT (Consejo Nacional de Ciencia y Tecnología) during the construction and operational phase of the Large Millimetre Telescope Alfonso Serrano, as well as support from the US National Science Foundation via the University Radio Observatory program, the Instituto Nacional de Astrofísica, Optica y Electrónica (INAOE) and the University of Massachusetts, Amherst (UMass). MC, EB, FCSM, MO and RLV work was supported by CONACyT research grants SEP-2009-134985 and SEP-2011-169554. GMK is supported by the Royal Society as a Royal Society University Research Fellow. CE is partly supported by Spanish grant AYA2014-55840-P. JPM is supported by a UNSW Vice Chancellor's Postdoctoral Fellowship. SL acknowledges support from CONACyT through grant 238631