756 research outputs found
Neutrino Phenomenology in a 3+1+1 Framework
Evidence continues to grow in the MiniBooNE (MB) antineutrino mode supporting
a low-energy excess compatible with the MB neutrino mode and possibly also
confirming the results of the LSND experiment. At least one sterile neutrino is
required to explain the anomalies consistent with the observations of other
experiments. At the same time, there is a strong tension between the positive
signals of LSND and MB and the null results of nu_e and nu_mu disappearance
experiments. We explore a scenario, first proposed in \cite{Nelson:2010hz},
where the presence of an additional heavy sterile neutrino (with mass well
above an eV) can alleviate tension between LSND, MB and the null results of
disappearance experiments. We compare and contrast this 3+1+1 scenario with the
more standard 3+1 scenario and carry out global fits to all oscillation data
including new 2011 MB anti-nu data. We find that the tension can be somewhat
alleviated and that a phenomenologically viable window for the heavy neutrino,
consistent with rare decays and BBN constraints, can be found if the fifth
neutrino has a mass of order 0.3 - 10 GeV. We also find, however, that the 2011
MB anti-nu data exacerbates the tension with null experiments in both the 3+1
and 3+1+1 models when the lowest energy bins are included, resulting in little
improvement in the global fit. We also discuss the implications of an
additional neutrino for the reactor and gallium anomalies, and show that an
oscillation explanation of the anomalies is disfavored by cosmological
considerations, direct searches, and precision electroweak tests.Comment: 22 pages, 5 figures; replaced to reflect journal versio
23 GHz VLBI Observations of SN 2008ax
We report on phase-referenced 23 GHz Very-Long-Baseline-Interferometry (VLBI)
observations of the type IIb supernova SN 2008ax, made with the Very Long
Baseline Array (VLBA) on 2 April 2008 (33 days after explosion). These
observations resulted in a marginal detection of the supernova. The total flux
density recovered from our VLBI image is 0.80.3 mJy (one standard
deviation). As it appears, the structure may be interpreted as either a
core-jet or a double source. However, the supernova structure could be somewhat
confused with a possible close by noise peak. In such a case, the recovered
flux density would decrease to 0.480.12 mJy, compatible with the flux
densities measured with the VLA at epochs close in time to our VLBI
observations. The lowest average expansion velocities derived from our
observations are km s (case of a double
source) and km s (taking the weaker source
component as a spurious, close by, noise peak, which is the more likely
interpretation). These velocities are 7.3 and 2 times higher, respectively,
than the maximum ejecta velocity inferred from optical-line observations.Comment: 4 pages, 3 figures. Accepted in A&A on 24/03/200
A robust ex vivo method to evaluate the diffusion properties of agents in biological tissues
A robust method is presented for evaluating the diffusion properties of chemicals in ex vivo biological tissues. Using this method that relies only on thickness and collimated transmittance measurements, the diffusion properties of glycerol, fructose, polypropylene glycol and water in muscle tissues were evaluated. Amongst other results, the diffusion coefficient of glycerol in colorectal muscle was estimated with a value of 3.3 × 10−7 cm2/s. Due to the robustness and simplicity of the method, it can be used in other fields of biomedical engineering, namely in organ cryoprotection and food industry
Transmission analysis of a large tuberculosis outbreak in London: a mathematical modelling study using genomic data
Outbreaks of tuberculosis (TB) - such as the large isoniazid-resistant outbreak centred on London, UK, which originated in 1995 - provide excellent opportunities to model transmission of this devastating disease. Transmission chains for TB are notoriously difficult to ascertain, but mathematical modelling approaches, combined with whole-genome sequencing data, have strong potential to contribute to transmission analyses. Using such data, we aimed to reconstruct transmission histories for the outbreak using a Bayesian approach, and to use machine-learning techniques with patient-level data to identify the key covariates associated with transmission. By using our transmission reconstruction method that accounts for phylogenetic uncertainty, we are able to identify 21 transmission events with reasonable confidence, 9 of which have zero SNP distance, and a maximum distance of 3. Patient age, alcohol abuse and history of homelessness were found to be the most important predictors of being credible TB transmitters
An Intermediate Luminosity Transient in NGC300: The Eruption of a Dust-Enshrouded Massive Star
[abridged] We present multi-epoch high-resolution optical spectroscopy,
UV/radio/X-ray imaging, and archival Hubble and Spitzer observations of an
intermediate luminosity optical transient recently discovered in the nearby
galaxy NGC300. We find that the transient (NGC300 OT2008-1) has a peak absolute
magnitude of M_bol~-11.8 mag, intermediate between novae and supernovae, and
similar to the recent events M85 OT2006-1 and SN2008S. Our high-resolution
spectra, the first for this event, are dominated by intermediate velocity
(~200-1000 km/s) hydrogen Balmer lines and CaII emission and absorption lines
that point to a complex circumstellar environment, reminiscent of the yellow
hypergiant IRC+10420. In particular, we detect broad CaII H&K absorption with
an asymmetric red wing extending to ~1000 km/s, indicative of gas infall onto a
massive and relatively compact star (blue supergiant or Wolf-Rayet star); an
extended red supergiant progenitor is unlikely. The origin of the inflowing gas
may be a previous ejection from the progenitor or the wind of a massive binary
companion. The low luminosity, intermediate velocities, and overall similarity
to a known eruptive star indicate that the event did not result in a complete
disruption of the progenitor. We identify the progenitor in archival Spitzer
observations, with deep upper limits from Hubble data. The spectral energy
distribution points to a dust-enshrouded star with a luminosity of about 6x10^4
L_sun, indicative of a ~10-20 M_sun progenitor (or binary system). This
conclusion is in good agreement with our interpretation of the outburst and
circumstellar properties. The lack of significant extinction in the transient
spectrum indicates that the dust surrounding the progenitor was cleared by the
outburst.Comment: Submitted to ApJ; emulateapj style; 39 pages; 26 figure
Consequences of sexual harassment in sport for female athletes
Sexual harassment research was first undertaken in the workplace and educational settings. Research on sexual harassment in sport is scarce but has grown steadily since the mid-1980s. Even so, very little is known about the causes and/or characteristics and/or consequences of sexual harassment in sport settings. This article reports on the findings from interviews with 25 elite female athletes in Norway who indicated in a prior survey (N =572) that they had experienced sexual harassment from someone in sport. The consequences of the incidents of sexual harassment that were reported were mostly negative, but some also reported that their experiences of sexual harassment had had no consequences for them. “Thinking about the incidents”, a “destroyed relationship to the coach”, and “more negative view of men in general” were the most often negative consequences mentioned. In addition, a surprising number had chosen to move to a different sport or to drop out of elite sport altogether because of the harassment
High-resolution observations of SN 2001gd in NGC 5033
We report on 8.4 GHz VLBI observations of SN2001gd in the spiral galaxy
NGC5033 made on 26 June 2002 and 8 April 2003. Our data nominally suggests a
relatively strong deceleration for the expansion of SN2001gd, but we cannot
dismiss the possibility of a free supernova expansion. From our VLBI
observations on 8 April 2003, we inferred a minimum total energy in
relativistic particles and magnetic fields in the supernova shell of E_min
=(0.3-14) 10^{47} ergs, and a corresponding equipartition average magnetic
field of B_min = (50--350) mG. We also present multiwavelength VLA measurements
of SN2001gd, which are well fit by an optically thin, synchrotron spectrum,
partially absorbed by thermal plasma. We obtain a supernova flux density of
(1.02 +/- 0.05) mJy at the observing frequency of 8.4 GHz for the second epoch,
which results in an isotropic radio luminosity of (6.0 +/- 0.3) * 10^{36} ergs
between 1.4 and 43.3 GHz, at an adopted distance of 13.1 Mpc. Finally, we
report on an XMM-Newton X-ray detection of SN2001gd on 18 December 2002. The
supernova X-ray spectrum is consistent with optically thin emission from a soft
component (associated with emission from the reverse shock) at a temperature
around 1 keV. The observed flux corresponds to an isotropic X-ray luminosity of
L_X = 1.4 +/- 0.4 * 10^{39} ergs/s in the (0.3-5) keV band. We suggest that
both radio and X-ray observations of SN2001gd indicate that a circumstellar
interaction similar to that displayed by SN1993J in M81 is taking place.Comment: 9 pages, 6 figures, 2 tables, accepted for publication in MNRA
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