Technical note: concentration and composition of airborne aerobic bacteria inside an enclosed rabbit shed

[EN] Numerous studies have been conducted to analyse bacterial aerosols in animal houses, which is beneficial for the control of animal diseases. However, little information on aerosols in enclosed rabbit sheds was available. An FA-1 sampler was employed to collect air samples in an enclosed rabbit house in the Qingdao region of China. Concentration, composition, and aerodynamics of bacterial aerosols inside the enclosed rabbit shed were systematically analysed. The concentration of airborne bacteria inside the rabbit shed was 2.11-6.36×104 colony forming unit/m3 (CFU/m3). Seventeen species of bacteria belonging to eight genera were identified. Among these, there were 11 species belonging to 4 genera of gram-positive bacteria, and 6 species belonging to 4 genera of gram-negative bacteria. The dominant species of bacteria were, in descending order, Micrococcus luteus (49.4%), Staphylococcus epidermidis (25.5%), and Alcaligenes odorans (10.2%). A total of about 76.3% of airborne bacteria was distributed in stages C-F of the FA-1 sampler (that ranges from A to F), with aerodynamic radii <3.3 μm in diameter. These particulates could enter lower respiratory tracks and even alveoli, posing a potential threat to the health of both animals and breeders.This study was supported by the National Natural Science Foundation of China (81501357).Li, S.; Li, M.; Mu, T.; Miao, Z. (2016). Technical note: concentration and composition of airborne aerobic bacteria inside an enclosed rabbit shed. World Rabbit Science. 24(1):71-75. https://doi.org/10.4995/wrs.2016.4170SWORD7175241Simpson, J. C., Niven, R. M., Pickering, C. A., Fletcher, A. M., Oldham, L. A., & Francis, H. M. (1998). Prevalence and predictors of work related respiratory symptoms in workers exposed to organic dusts. Occupational and Environmental Medicine, 55(10), 668-672. doi:10.1136/oem.55.10.66

Search for electroweak production of single top quarks in ppˉp\bar{p} collisions.

We present a search for electroweak production of single top quarks in the electron+jets and muon+jets decay channels. The measurements use ~90 pb^-1 of data from Run 1 of the Fermilab Tevatron collider, collected at 1.8 TeV with the DZero detector between 1992 and 1995. We use events that include a tagging muon, implying the presence of a b jet, to set an upper limit at the 95% confidence level on the cross section for the s-channel process ppbar->tb+X of 39 pb. The upper limit for the t-channel process ppbar->tqb+X is 58 pb. (arXiv

Helium identification with LHCb

The identification of helium nuclei at LHCb is achieved using a method based on measurements of ionisation losses in the silicon sensors and timing measurements in the Outer Tracker drift tubes. The background from photon conversions is reduced using the RICH detectors and an isolation requirement. The method is developed using pp collision data at √(s) = 13 TeV recorded by the LHCb experiment in the years 2016 to 2018, corresponding to an integrated luminosity of 5.5 fb-1. A total of around 105 helium and antihelium candidates are identified with negligible background contamination. The helium identification efficiency is estimated to be approximately 50% with a corresponding background rejection rate of up to O(10^12). These results demonstrate the feasibility of a rich programme of measurements of QCD and astrophysics interest involving light nuclei

Curvature-bias corrections using a pseudomass method

Momentum measurements for very high momentum charged particles, such as muons from electroweak vector boson decays, are particularly susceptible to charge-dependent curvature biases that arise from misalignments of tracking detectors. Low momentum charged particles used in alignment procedures have limited sensitivity to coherent displacements of such detectors, and therefore are unable to fully constrain these misalignments to the precision necessary for studies of electroweak physics. Additional approaches are therefore required to understand and correct for these effects. In this paper the curvature biases present at the LHCb detector are studied using the pseudomass method in proton-proton collision data recorded at centre of mass energy √(s)=13 TeV during 2016, 2017 and 2018. The biases are determined using Z→μ + μ - decays in intervals defined by the data-taking period, magnet polarity and muon direction. Correcting for these biases, which are typically at the 10-4 GeV-1 level, improves the Z→μ + μ - mass resolution by roughly 18% and eliminates several pathological trends in the kinematic-dependence of the mean dimuon invariant mass

Momentum scale calibration of the LHCb spectrometer

For accurate determination of particle masses accurate knowledge of the momentum scale of the detectors is crucial. The procedure used to calibrate the momentum scale of the LHCb spectrometer is described and illustrated using the performance obtained with an integrated luminosity of 1.6 fb-1 collected during 2016 in pp running. The procedure uses large samples of J/ψ → μ + μ - and B+ → J/ψ K + decays and leads to a relative accuracy of 3 × 10-4 on the momentum scale

THE RATE OF BINARY BLACK HOLE MERGERS INFERRED FROM ADVANCED LIGO OBSERVATIONS SURROUNDING GW150914

A transient gravitational-wave signal, GW150914, was identi fi ed in the twin Advanced LIGO detectors on 2015 September 2015 at 09:50:45 UTC. To asse ss the implications of this discovery, the detectors remained in operation with unchanged con fi gurations over a period of 39 days around the time of t he signal. At the detection statistic threshold corresponding to that observed for GW150914, our search of the 16 days of simultaneous two-detector observational data is estimated to have a false-alarm rate ( FAR ) of < ́ -- 4.9 10 yr 61 , yielding a p -value for GW150914 of < ́ - 210 7 . Parameter estimation follo w-up on this trigger identi fi es its source as a binary black hole ( BBH ) merger with component masses ( )( ) = - + - + mm M ,36,29 12 4 5 4 4 at redshift = - + z 0.09 0.04 0.03 ( median and 90% credible range ) . Here, we report on the constraints these observations place on the rate of BBH coalescences. Considering only GW150914, assuming that all BBHs in the universe have the same masses and spins as this event, imposing a search FAR threshold of 1 per 100 years, and assuming that the BBH merger rate is constant in the comoving frame, we infer a 90% credible range of merger rates between – -- 2 53 Gpc yr 31 ( comoving frame ) . Incorporating all search triggers that pass a much lower threshold while accounting for the uncerta inty in the astrophysical origin of each trigger, we estimate a higher rate, ranging from – -- 13 600 Gpc yr 31 depending on assumptions about the BBH mass distribution. All together, our various rate estimat es fall in the conservative range – -- 2 600 Gpc yr 31

Selective photon-breaking of C-S bonds in polythiophene to form quasi-one-dimensional carbon chains in cubic nanocrystals

10.1117/12.456811Proceedings of SPIE - The International Society for Optical Engineering442635-38PSIS

Formation of quasi-one-dimensional carbon chains in cubic nanocrystals by photon-breaking of C-S bonds inpolythiophene

Journal of Materials Research16102793-2797JMRE