Neutrino oscillation models involving one extra mass eigenstate beyond the standard three (3+1) are fit to global short baseline experimental data and the recent IceCube ν_{μ}+νover ¯_{μ} ...disappearance search result. We find a best fit of Δm_{41}^{2}=1.75 eV^{2} with Δχ_{null-min}^{2}/d.o.f. of 50.61/4. We find that the combined IceCube and short baseline data constrain θ_{34} to <80°(<6°) at 90% C.L. for Δm_{41}^{2}≈2(6) eV^{2}, which is improved over present limits. Incorporating the IceCube information provides the first constraints on all entries of the 3+1 mixing matrix.
Recent global fits to short-baseline neutrino oscillation data have been performed finding preference for a sterile neutrino solution (3+1) over null. In the most recent iteration, it was pointed out ...that an unstable sterile neutrino (3+1+decay) may be a better description of the data. This is due to the fact that this model significantly reduces the tension between appearance and disappearance datasets. In this work, we add a 1-year IceCube dataset to the global fit obtaining new results for the standard 3+1 and 3+1+decay sterile neutrino scenarios. We find that the 3+1+decay model provides a better fit than the 3+1, even in the presence of IceCube, with reduced appearance to disappearance tension. The 3+1+decay model is a 5.4σ improvement over the null hypothesis and a 2.8σ improvement over the standard 3+1 model.
Uptake and metabolism of allyl thiol and allyl cysteine by undifferentiated callus of garlic and onion led to the formation of the flavour precursors alliin and isoalliin.
The path of synthesis of ...alkyl cysteine sulphoxides, or flavour precursors, in the
Alliums is still speculative. There are two proposed routes for alliin biosynthesis, one is from serine and allyl thiol while the other is from glutathione and an allyl source via γ glutamyl peptides. The routes have been investigated by exposing undifferentiated callus cultures of garlic and onion to potential pathway intermediates. After a period of incubation of 2 days the callus was extracted, and analysed for flavour precursors and related compounds by HPLC. Standards of alliin, isoallin and propiin were synthesised and their identity confirmed by HPLC and NMR. Putative intermediates selected included the amino acids serine and cysteine, as well as more complex intermediates such as allylthiol, allyl cysteine and glutathione. Both garlic and onion tissue cultures were able to synthesize alliin following incubation with allylthiol, and cysteine conjugates such as allyl cysteine. The ability of the tissue cultures to form alliin from intermediates was compatible with the proposed routes of synthesis of alliin.
We report observations of a direct ionospheric plasma outflow response to the incidence of an interplanetary shock and associated coronal mass ejection (CME) upon the earth's magnetosphere. Data from ...the WIND spacecraft, 185 RE upstream, document the passage of an interplanetary shock at 23:20 UT on 24 Sept. 1998. The polar cap plasma environment sampled by the POLAR spacecraft changed abruptly at 23:45 UT, reflecting the compressional displacement of the geopause relative to the spacecraft. POLAR left the polar wind outflow region and entered the mantle flows. Descending toward the dayside cusp region, POLAR later returned from the mantle to an enhanced polar wind flux dominated by O+ plasma and eventually containing molecular ions. The enhanced and O+− dominated outflow continued as the spacecraft passed through the high altitude cleft and then the southern cleft at lower altitude. Such a direct response of the ionosphere to solar wind dynamic pressure disturbances may have important impacts on magnetospheric dynamics.
We measure a large set of observables in inclusive charged current muon neutrino scattering on argon with the MicroBooNE liquid argon time projection chamber operating at Fermilab. We evaluate three ...neutrino interaction models based on the widely used GENIE event generator using these observables. The measurement uses a data set consisting of neutrino interactions with a final state muon candidate fully contained within the MicroBooNE detector. These data were collected in 2016 with the Fermilab Booster Neutrino Beam, which has an average neutrino energy of Formula omitted, using an exposure corresponding to Formula omitted protons-on-target. The analysis employs fully automatic event selection and charged particle track reconstruction and uses a data-driven technique to separate neutrino interactions from cosmic ray background events. We find that GENIE models consistently describe the shapes of a large number of kinematic distributions for fixed observed multiplicity.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Homologation of the nucleophilic glycine equivalent Ni-Gly-PABP Ni(II) complex of glycine Schiff base with 2-N-(α-picolyl)aminobenzophenone (PABP) 2 via alkyl halide alkylations and Michael addition ...reactions was systematically studied as a general method for preparing symmetrically α,α-disubstituted α-amino acids (sym-α,α-AA). The dialkylation reactions are conducted under operationally convenient conditions without recourse to inert atmosphere, dried solvents, and low temperatures, thus enjoying key advantages of the experimental simplicity and attractive cost structure. The method has been shown to be particularly successful for the dialkylation of complex 2 with activated and nonactivated alkyl halides, including propargyl derivatives, affording a generalized and practical access to the corresponding sym-α,α-AA. This study has also shown some limitation of the method, as it cannot be extended to α- or β-branched alkyl halides or Michael acceptors to be used for the dialkylation of glycine equivalent 2. High chemical yields of the dialkylated products, combined with the simplicity of the experimental procedure, render this method worth immediate use for multigram scale preparation of the sym-α,α-AA.
We review the status of searches for sterile neutrinos in the ∼1eV range, with an emphasis on the latest results from short baseline oscillation experiments and how they fit within sterile neutrino ...oscillation models. We present global fit results to a three-active-flavor plus one-sterile-flavor model (3+1), where we find an improvement of Δχ2=35 for 3 additional parameters compared to a model with no sterile neutrino. This is a 5σ improvement, indicating that an effect that is like that of a sterile neutrino is highly preferred by the data. However we note that separate fits to the appearance and disappearance oscillation data sets within a 3+1 model do not show the expected overlapping allowed regions in parameter space. This “tension” leads us to explore two options: 3+2, where a second additional mass state is introduced, and a 3+1+decay model, where the ν4 state can decay to invisible particles. The 3+1+decay model, which is also motivated by improving compatibility with cosmological observations, yields the larger improvement, with a Δχ2=8 for 1 additional parameter beyond the 3+1 model, which is a 2.6σ improvement. Moreover the tension between appearance and disappearance experiments is reduced compared to 3+1, although disagreement remains. In these studies, we use a frequentist approach and also a Bayesian method of finding credible regions.
With respect to this tension, we review possible problems with the global fitting method. We note multiple issues, including problems with reproducing the experimental results, especially in the case of experiments that do not provide adequate data releases. We discuss an unexpected 5 MeV excess, observed in the reactor flux energy spectrum, that may be affecting the oscillation interpretation of the short baseline reactor data. We emphasize the care that must be taken in mapping to the true neutrino energy in the case of oscillation experiments that are subject to multiple interaction modes and nuclear effects. We point to problems with the “Parameter-Goodness-of-Fit test” that is used to quantify the tension. Lastly, we point out that analyses presenting limits often receive less scrutiny that signals.
While we provide a snapshot of the status of sterile neutrino searches today and global fits to their interpretation, we emphasize that this is a fast-moving field. We briefly review experiments that are expected to report new data in the immediate future. Lastly, we consider the 5-year horizon, where we propose that decay-at-rest neutrino sources are the best method of finally resolving the confusing situation.
This paper will discuss a new method of signal read-out from photon detectors in ultra-large, underground liquid argon time projection chambers. In this design, the signal from the light collection ...system is coupled via capacitive plates to the TPC wire-planes. This signal is then read out using the same cabling and electronics as the charge information. This greatly benefits light collection: it eliminates the need for an independent readout, substantially reducing cost; it reduces the number of cables in the vapor region of the TPC that can produce impurities; and it cuts down on the number of feed-throughs in the cryostat wall that can cause heat-leaks and potential points of failure. We present experimental results that demonstrate the sensitivity of a LArTPC wire plane to photon detector signals. We also simulate the effect of a 1 mus shaping time and a 2 MHz sampling rate on these signals in the presence of noise, and find that a single photoelectron timing resolution of ~30 ns can be achieved.
Neutrino oscillation models involving extra mass eigenstates beyond the standard three (3+N) are fit to global short baseline experimental data. We find that 3+1 has a best fit of Δm412=1.75 eV2 with ...a Δχnull-min2 (dof) of 52.34 (3). The 3+2 fit has a Δχnull-min2 (dof) of 56.99 (7). For the first time, we show Bayesian credible intervals for a 3+1 model. These are found to be in agreement with frequentist intervals. The results of these new fits favor a higher Δm2 value than previous studies, which may have an impact on future sterile neutrino searches such as the Fermilab SBN program.
Neutrals created by charge‐exchange of low‐energy (∼10–100 eV) ion outflow from the ionosphere are imaged by the Low Energy Neutral Atom (LENA) imager on the IMAGE spacecraft. Comparing the neutral ...flux with changes in the solar wind during an ion outflow event on 24 June 2000 indicates that changes in solar wind density (and therefore dynamic pressure) are associated with episodic bursts of ion outflow. LENA images show that these bursts are confined to the duskside. Simultaneous images of the aurora from the IMAGE FUV Wideband Imaging Camera indicate that these episodic bursts on the duskside are associated with increased duskside auroral emissions. The pitch angle and charge exchange altitude for the ion outflow distributions are estimated by applying field line tracing in a model magnetic field and assuming that the outflow occurs in the auroral zone. The pitch angle information places constraints on the neutral atom images, indicating that the ion outflow observed on the duskside probably consists of high pitch angle conics and that field‐aligned ion outflow from other parts of the oval cannot be observed from the IMAGE spacecraft location.
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