94 research outputs found
3-D model simulations of dynamical and microphysical interactions in pyroconvective clouds under idealized conditions
Abstract. Dynamical and microphysical processes in pyroconvective clouds in mid-latitude conditions are investigated using idealized three-dimensional simulations with the Active Tracer High resolution Atmospheric Model (ATHAM). A state-of-the-art two-moment microphysical scheme building upon a realistic parameterization of cloud condensation nuclei (CCN) activation has been implemented in order to study the influence of aerosol concentration on cloud development. The results show that aerosol concentration influences the formation of precipitation. For low aerosol concentrations (NCN = 200 cm−3), rain droplets are rapidly formed by autoconversion of cloud droplets. This also triggers the formation of large graupel and hail particles, resulting in an early onset of precipitation. With increasing aerosol concentration (NCN = 1000 cm−3 and NCN = 20 000 cm−3) the formation of rain droplets is delayed due to more but smaller cloud droplets. Therefore, the formation of ice crystals and snowflakes becomes more important for the eventual formation of graupel and hail, which is delayed at higher aerosol concentrations. This results in a delay of the onset of precipitation and a reduction of its intensity with increasing aerosol concentration. This study is the first detailed investigation of the interaction between cloud microphysics and the dynamics of a pyroconvective cloud using the combination of a high-resolution atmospheric model and a detailed microphysical scheme.
This work has been supported by an International Max Planck Research School fellowship and the Max
Planck Society.This is the final published version. It first appeared at http://www.atmos-chem-phys.net/14/7573/2014/acp-14-7573-2014.html
Measurement of the Boson Mass
A measurement of the mass of the boson is presented based on a sample of
5982 decays observed in collisions at
= 1.8~TeV with the D\O\ detector during the 1992--1993 run. From a
fit to the transverse mass spectrum, combined with measurements of the
boson mass, the boson mass is measured to be .Comment: 12 pages, LaTex, style Revtex, including 3 postscript figures
(submitted to PRL
Search for Production via Trilepton Final States in collisions at TeV
We have searched for associated production of the lightest chargino,
, and next-to-lightest neutralino, , of the
Minimal Supersymmetric Standard Model in collisions at
\mbox{ = 1.8 TeV} using the \D0 detector at the Fermilab Tevatron
collider. Data corresponding to an integrated luminosity of 12.5 \ipb
were examined for events containing three isolated leptons. No evidence for
pair production was found. Limits on
BrBr are
presented.Comment: 17 pages (13 + 1 page table + 3 pages figures). 3 PostScript figures
will follow in a UUEncoded, gzip'd, tar file. Text in LaTex format. Submitted
to Physical Review Letters. Replace comments - Had to resumbmit version with
EPSF directive
Second Generation Leptoquark Search in p\bar{p} Collisions at = 1.8 TeV
We report on a search for second generation leptoquarks with the D\O\
detector at the Fermilab Tevatron collider at = 1.8 TeV.
This search is based on 12.7 pb of data. Second generation leptoquarks
are assumed to be produced in pairs and to decay into a muon and quark with
branching ratio or to neutrino and quark with branching ratio
. We obtain cross section times branching ratio limits as a function
of leptoquark mass and set a lower limit on the leptoquark mass of 111
GeV/c for and 89 GeV/c for at the 95%\
confidence level.Comment: 18 pages, FERMILAB-PUB-95/185-
The Azimuthal Decorrelation of Jets Widely Separated in Rapidity
This study reports the first measurement of the azimuthal decorrelation
between jets with pseudorapidity separation up to five units. The data were
accumulated using the D{\O}detector during the 1992--1993 collider run of the
Fermilab Tevatron at 1.8 TeV. These results are compared to
next--to--leading order (NLO) QCD predictions and to two leading--log
approximations (LLA) where the leading--log terms are resummed to all orders in
. The final state jets as predicted by NLO QCD
show less azimuthal decorrelation than the data. The parton showering LLA Monte
Carlo {\small HERWIG} describes the data well; an analytical LLA prediction
based on BFKL resummation shows more decorrelation than the data.Comment: 6 pages with 4 figures, all uuencoded and gzippe
Jet Production via Strongly-Interacting Color-Singlet Exchange in Collisions
A study of the particle multiplicity between jets with large rapidity
separation has been performed using the D{\O}detector at the Fermilab Tevatron
Collider operating at TeV. A significant excess of
low-multiplicity events is observed above the expectation for color-exchange
processes. The measured fractional excess is , which is consistent with a strongly-interacting
color-singlet (colorless) exchange process and cannot be explained by
electroweak exchange alone. A lower limit of 0.80% (95% C.L.) is obtained on
the fraction of dijet events with color-singlet exchange, independent of the
rapidity gap survival probability.Comment: 15 pages (REVTeX), 3 PS figs (uuencoded/tar compressed, epsf.sty)
Complete postscript available at http://d0sgi0.fnal.gov/d0pubs/journals.html
Submitted to Physical Review Letter
Ultrasonic intensification as a tool for enhanced microbial biofuel yields
peer-reviewedUltrasonication has recently received attention as a novel bioprocessing tool for process intensification in many areas
of downstream processing. Ultrasonic intensification (periodic ultrasonic treatment during the fermentation process)
can result in a more effective homogenization of biomass and faster energy and mass transfer to biomass over short
time periods which can result in enhanced microbial growth. Ultrasonic intensification can allow the rapid selective
extraction of specific biomass components and can enhance product yields which can be of economic benefit. This
review focuses on the role of ultrasonication in the extraction and yield enhancement of compounds from various
microbial sources, specifically algal and cyanobacterial biomass with a focus on the production of biofuels. The
operating principles associated with the process of ultrasonication and the influence of various operating conditions
including ultrasonic frequency, power intensity, ultrasonic duration, reactor designs and kinetics applied for ultrasonic
intensification are also described
Measurement of the gauge boson couplings in Collisions at TeV
The gauge boson couplings were measured using () events at TeV observed with the
{D\O} detector at the Fermilab Tevatron Collider. The signal, obtained from the
data corresponding to an integrated luminosity of , agrees
well with the Standard Model prediction. A fit to the photon transverse energy
spectrum yields limits at the 95% confidence level on the CP--conserving
anomalous coupling parameters of ( = 0) and
( = 0).Comment: 16pages (14pages + 2figure pages) Uses ReVTEX Two postscript files
for figures will follow immediatel
Measurement of the and Couplings in Collisions at TeV
We have directly measured the ZZ-gamma and Z-gamma-gamma couplings by
studying p pbar --> l+ l- gamma + X, (l = e, mu) events at the CM energy of
1.813.3 pb^-1)
for the electron (muon) channel, yields the following 95% confidence level
limits on the anomalous CP-conserving ZZ-gamma couplings: -1.9 < h^Z_30 < 1.8
(h^Z_40 = 0), and -0.5 < h^Z_40 < 0.5 (h^Z_30 = 0), for a form-factor scale
Lambda = 500 GeV. Limits for the Z-gamma-gamma$ couplings and CP-violating
couplings are also discussed.Comment: 11 pages, 1 table, and 3 figure
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