6,385 research outputs found
High emission rate of sulfuric acid from Bezymianny volcano, Kamchatka
High concentrations of primary sulfuric acid (H2SO4) in fumarolic gases and high emission rate of sulfuric acid aerosol in the plume were measured at Bezymianny volcano, an active dome-growing andesitic volcano in central Kamchatka. Using direct sampling, filter pack sampling, and differential optical absorption spectroscopy measurements, we estimated an average emission of H2SO4 at 243 ± 75 t/d in addition to an average SO2 emission of 212 ± 65 t/d. The fumarolic gases of Bezymianny correspond to arc gases released by several magma bodies at different stages of degassing and contain 25-92% of entrained air. H2SO4 accounts for 6-87 mol% of the total sulfur content, 42.8 mol% on average, and SO2 is the rest. The high H2SO4 in Bezymianny fumaroles can be explained by catalytic oxidation of SO2 inside the volcanic dome. Because sulfate aerosol is impossible to measure remotely, the total sulfur content in a plume containing significant H2SO4 may be seriously underestimated
Exploring the relation between preoperative physical functioning and the impact of major complications in patients following pancreatic resection
BACKGROUND: This study aimed to evaluate the association between preoperative level of physical functioning and time to recovery of physical functioning, postoperative complications, and the impact of postoperative major complications in patients undergoing elective pancreatic resection. Additionally, prediction models to identify high-risk patients for developing a major complication were externally validated. METHODS: Perioperative data of patients who underwent pancreatic resection were analysed. Primary outcomes were time to recovery of physical functioning and postoperative major complications. Impact of a major complication was explored by evaluating its effect on time to recovery of physical functioning. Risk-prediction models were retrieved following a systematic review. RESULTS: Multivariable analysis (n = 63) showed that ASA grade III (OR 3.498) and preoperative platelet count (OR 1.005) were associated with major complications, whereas aerobic capacity (OR 0.347) was associated with time to recovery of physical functioning. Age, preoperative aerobic capacity, functional mobility, and perceived level of functional capacity were associated with the impact of a major complication. The AUC of two risk prediction models were 0.556 and 0.701. CONCLUSION: Preoperative parameters of physical function were associated with postoperative outcomes and may be useful in outcome prediction, although future approaches should not only register the incidence of major complications but also take the impact of a complication on a patient's physical functioning into account
How metal films de-wet substrates - identifying the kinetic pathways and energetic driving forces
We study how single-crystal chromium films of uniform thickness on W(110)
substrates are converted to arrays of three-dimensional (3D) Cr islands during
annealing. We use low-energy electron microscopy (LEEM) to directly observe a
kinetic pathway that produces trenches that expose the wetting layer. Adjacent
film steps move simultaneously uphill and downhill relative to the staircase of
atomic steps on the substrate. This step motion thickens the film regions where
steps advance. Where film steps retract, the film thins, eventually exposing
the stable wetting layer. Since our analysis shows that thick Cr films have a
lattice constant close to bulk Cr, we propose that surface and interface stress
provide a possible driving force for the observed morphological instability.
Atomistic simulations and analytic elastic models show that surface and
interface stress can cause a dependence of film energy on thickness that leads
to an instability to simultaneous thinning and thickening. We observe that
de-wetting is also initiated at bunches of substrate steps in two other
systems, Ag/W(110) and Ag/Ru(0001). We additionally describe how Cr films are
converted into patterns of unidirectional stripes as the trenches that expose
the wetting layer lengthen along the W[001] direction. Finally, we observe how
3D Cr islands form directly during film growth at elevated temperature. The Cr
mesas (wedges) form as Cr film steps advance down the staircase of substrate
steps, another example of the critical role that substrate steps play in 3D
island formation
Coherent control of orbital wavefunctions in the quantum spin liquid
Resonant driving of electronic transitions with coherent laser sources
creates quantum coherent superpositions of the involved electronic states. Most
time-resolved studies have focused on gases or isolated subsystems embedded in
insulating solids, aiming for applications in quantum information. Here, we
demonstrate coherent control of orbital wavefunctions in pyrochlore
, which forms an interacting spin liquid ground state. We
show that resonant excitation with a strong THz pulse creates a coherent
superposition of the lowest energy Tb 4f states before the magnetic
interactions eventually dephase them. The coherence manifests itself as a
macroscopic oscillating magnetic dipole, which is detected by ultrafast
resonant x-ray diffraction. The induced quantum coherence demonstrates coherent
control of orbital wave functions, a new tool for the ultrafast manipulation
and investigation of quantum materials
Test results from a uranium hadron calorimeter using wire chamber readout
A uranium gas sampling calorimeter has been tested with electrons and pions between 1 and 50 GeV. A comparative evaluation of the response and the resolution for proportional and streamer mode operation of the gas wire chamber detectors is given for two different gas mixtures.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26795/1/0000351.pd
Therapeutic effects of functional orthodontic appliances on cervical spine posture: a retrospective cephalometric study
Taxing the Informal Economy: The Current State of Knowledge and Agendas for Future Research
This paper reviews the literature on taxation of the informal economy, taking stock of key debates
and drawing attention to recent innovations. Conventionally, the debate on whether to tax has frequently focused
on the limited revenue potential, high cost of collection, and potentially adverse impact on small firms. Recent
arguments have increasingly emphasised the more indirect benefits of informal taxation in relation to economic
growth, broader tax compliance, and governance. More research is needed, we argue, into the relevant costs and
benefits for all, including quasi-voluntary compliance, political and administrative incentives for reform, and
citizen-state bargaining over taxation
Study of Leading Hadrons in Gluon and Quark Fragmentation
The study of quark jets in e+e- reactions at LEP has demonstrated that the
hadronisation process is reproduced well by the Lund string model. However, our
understanding of gluon fragmentation is less complete. In this study enriched
quark and gluon jet samples of different purities are selected in three-jet
events from hadronic decays of the Z collected by the DELPHI experiment in the
LEP runs during 1994 and 1995. The leading systems of the two kinds of jets are
defined by requiring a rapidity gap and their sum of charges is studied. An
excess of leading systems with total charge zero is found for gluon jets in all
cases, when compared to Monte Carlo Simulations with JETSET (with and without
Bose-Einstein correlations included) and ARIADNE. The corresponding leading
systems of quark jets do not exhibit such an excess. The influence of the gap
size and of the gluon purity on the effect is studied and a concentration of
the excess of neutral leading systems at low invariant masses (<~ 2 GeV/c^2) is
observed, indicating that gluon jets might have an additional hitherto
undetected fragmentation mode via a two-gluon system. This could be an
indication of a possible production of gluonic states as predicted by QCD.Comment: 19 pages, 6 figures, Accepted by Phys. Lett.
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