1,181 research outputs found
Search for Lorentz Invariance and CPT Violation with the MINOS Far Detector
We searched for a sidereal modulation in the MINOS far detector neutrino rate. Such a signal would be
a consequence of Lorentz and CPT violation as described by the standard-model extension framework. It
also would be the first detection of a perturbative effect to conventional neutrino mass oscillations. We
found no evidence for this sidereal signature, and the upper limits placed on the magnitudes of the Lorentz
and CPT violating coefficients describing the theory are an improvement by factors of 20–510 over the
current best limits found by using the MINOS near detector
Improved Measurement of Muon Antineutrino Disappearance in MINOS
We report an improved measurement of ν̅_μ disappearance over a distance of 735 km using the MINOS detectors and the Fermilab Main Injector neutrino beam in a ν̅_μ-enhanced configuration. From a total exposure of 2.95×10^20 protons on target, of which 42% have not been previously analyzed, we make the most precise measurement of Δm̅^2=[2.62_(-0.28)^(+0.31)(stat)±0.09(syst)]×10^(-3) eV^2 and constrain the ν_μ mixing angle sin^(2)(2θ̅)>0.75 (90% C.L.). These values are in agreement with Δm^2 and sin^(2)(2θ) measured for νμ, removing the tension reported in [ P. Adamson et al. Phys. Rev. Lett. 107 021801 (2011)]
Polyhedral units and network connectivity in calcium aluminosilicate glasses from high-energy x-ray diffraction
Structure factors for Cax/2AlxSi1-xO2 glasses (x=0,0.25,0.5,0.67) extended to
a wave vector of magnitude Q= 40 1/A have been obtained by high-energy x-ray
diffraction. For the first time, it is possible to resolve the contributions of
Si-O, Al-O and Ca-O coordination polyhedra to the experimental atomic pair
distribution functions (PDF). It has been found that both Si and Al are
four-fold coordinated and so participate in a continuous tetrahedral network at
low values of x. The number of network breaking defects in the form of
non-bridging oxygens (NBO's) increases slowly with x until x=0.5 (NBO's ~ 10%
at x=0.5). By x=0.67 the network breaking defects become significant as
evidenced by the significant drop in the average coordination number of Si. By
contrast, Al-O tetrahedra remain free of NBO's and fully integrated in the
Al/Si-O network for all values of x. Calcium maintains a rather uniform
coordination sphere of approximately 5 oxygen atoms for all values of x. The
results suggest that not only Si/Al-O tetrahedra but Ca-O polyhedra, too, play
a role in determining the glassy structure
Iron oxidation at low temperature (260–500 C) in air and the effect of water vapor
The oxidation of iron has been studied at low temperatures (between 260 and 500 C) in dry air or air with 2 vol% H2O, in the framework of research on dry corrosion of nuclear waste containers during long-term interim storage. Pure iron is regarded as a model material for low-alloyed steel. Oxidation tests were performed in a thermobalance (up to 250 h) or in a laboratory furnace (up to 1000 h). The oxide scales formed were characterized using SEM-EDX, TEM, XRD, SIMS and EBSD techniques. The parabolic rate constants deduced from microbalance experiments were found to be in good agreement with the few existing values of the literature. The presence of water vapor in air was found to strongly influence the transitory stages of the kinetics. The entire structure of the oxide scale was composed of an internal duplex magnetite scale made of columnar grains and an external hematite scale made of equiaxed grains. 18O tracer experiments performed at 400 C allowed to propose a growth mechanism of the scale
Nanostructure of cellulose microfibrils in spruce wood
The structure of cellulose microfibrils in wood is not known in detail, despite the abundance of cellulose in woody biomass and its importance for biology, energy, and engineering. The structure of the microfibrils of spruce wood cellulose was investigated using a range of spectroscopic methods coupled to small-angle neutron and wide-angle X-ray scattering. The scattering data were consistent with 24-chain microfibrils and favored a “rectangular” model with both hydrophobic and hydrophilic surfaces exposed. Disorder in chain packing and hydrogen bonding was shown to increase outwards from the microfibril center. The extent of disorder blurred the distinction between the I alpha and I beta allomorphs. Chains at the surface were distinct in conformation, with high levels of conformational disorder at C-6, less intramolecular hydrogen bonding and more outward-directed hydrogen bonding. Axial disorder could be explained in terms of twisting of the microfibrils, with implications for their biosynthesis
Informational needs of general practitioners regarding discharge medication: content, timing and pharmacotherapeutic advice
textabstractObjective: To investigate the needs of Dutch general practitioners on discharge medication, both regarding content, timing and the appreciation of pharma-cotherapeutic advices from clinical pharmacists. Setting: A general teaching hospital in Amsterdam, the Netherlands. Method: A prospective observational study was performed. A questionnaire with regard to the content, optimal timing (including way of information transfer) and appreciation of pharmacotherapeutic advices was posted to 464 general practitioners. One reminder was sent. Main outcome measure: Description of the needs of general practitioners was assessed. For each question and categories of comments frequency tables were made. The Fisher-exact test was used to study associations between the answers to the questions. Results: In total, 149 general practitioners (32%) responded. Most general practitioners (75%) experienced a delay in receiving discharge medication information and preferred to receive this on the day of discharge. GPs wished to receive this information mainly through e-mail (44%). There was a significant correlation (P = 0.002) between general practitioners who wanted to know whether and why medication had been stopped (87%) and changed (88%) during hospital admission. The general practitioners (88%) appreciated pharmacotherapeutic advices from clinical pharmacists. Conclusion: This study indicates how information transfer on discharge medication to GPs can be optimised in the Netherlands. The information arrives late and GPs want to be informed on the day of discharge mainly by e-mail. GPs wish to know why medication is changed or discontinued and appreciate pharmacotherapeutic advices from clinical pharmacists
Enumerating Isolated Cliques in Temporal Networks
Isolation is a concept from the world of clique enumeration that is mostly
used to model communities that do not have much contact to the outside world.
Herein, a clique is considered isolated if it has few edges connecting it to
the rest of the graph. Motivated by recent work on enumerating cliques in
temporal networks, we lift the isolation concept to this setting. We discover
that the addition of the time dimension leads to six distinct natural isolation
concepts. Our main contribution is the development of fixed-parameter
enumeration algorithms for five of these six clique types employing the
parameter "degree of isolation". On the empirical side, we implement and test
these algorithms on (temporal) social network data, obtaining encouraging
preliminary results
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