3,060 research outputs found
Application of COMPOCHIP Microarray to Investigate the Bacterial Communities of Different Composts
A microarray spotted with 369 different 16S rRNA gene probes specific to microorganisms involved in the degradation process of organic waste during composting was developed. The microarray was tested with pure cultures, and of the 30,258 individual probe-target hybridization reactions performed, there were only 188 false positive (0.62%) and 22 false negative signals (0.07%). Labeled target DNA was prepared by polymerase chain reaction amplification of 16S rRNA genes using a Cy5-labeled universal bacterial forward primer and a universal reverse primer. The COMPOCHIP microarray was applied to three different compost types (green compost, manure mix compost, and anaerobic digestate compost) of different maturity (2, 8, and 16 weeks), and differences in the microorganisms in the three compost types and maturity stages were observed. Multivariate analysis showed that the bacterial composition of the three composts was different at the beginning of the composting process and became more similar upon maturation. Certain probes (targeting Sphingobacterium, Actinomyces, Xylella/Xanthomonas/ Stenotrophomonas, Microbacterium, Verrucomicrobia, Planctomycetes, Low G + C and Alphaproteobacteria) were more influential in discriminating between different composts. Results from denaturing gradient gel electrophoresis supported those of microarray analysis. This study showed that the COMPOCHIP array is a suitable tool to study bacterial communities in composts
A multiwavelength numerical model in support of quantitative retrievals of aerosol properties from automated lidar ceilometers and test applications for AOT and PM10 estimation
Abstract. The use of automated lidar ceilometer (ALC) systems for the
aerosol vertically resolved characterization has increased in recent
years thanks to their low construction and operation costs and their
capability of providing continuous unattended measurements. At the same time
there is a need to convert the ALC signals into usable geophysical
quantities. In fact, the quantitative assessment of the aerosol properties
from ALC measurements and the relevant assimilation in meteorological
forecast models is amongst the main objectives of the EU COST Action TOPROF
("Towards operational ground-based profiling with ALCs, Doppler lidars and
microwave radiometers for improving weather forecasts"). Concurrently, the E-PROFILE program of the European
Meteorological Services Network (EUMETNET) focuses on the harmonization of
ALC measurements and data provision across Europe. Within these frameworks,
we implemented a model-assisted methodology to retrieve key aerosol
properties (extinction coefficient, surface area, and volume) from elastic
lidar and/or ALC measurements. The method is based on results from a large
set of aerosol scattering simulations (Mie theory) performed at UV, visible,
and near-IR wavelengths using a Monte Carlo approach to select the input
aerosol microphysical properties. An average "continental aerosol type"
(i.e., clean to moderately polluted continental aerosol conditions) is
addressed in this study. Based on the simulation results, we derive mean
functional relationships linking the aerosol backscatter coefficients to the
abovementioned variables. Applied in the data inversion of single-wavelength
lidars and/or ALCs, these relationships allow quantitative determination of
the vertically resolved aerosol backscatter, extinction, volume, and surface
area and, in turn, of the extinction-to-backscatter ratios (i.e., the
lidar ratios, LRs) and extinction-to-volume conversion factor
(cv) at 355, 532, and 1064 nm. These variables provide valuable
information for visibility, radiative transfer, and air quality applications.
This study also includes (1) validation of the model simulations with real
measurements and (2) test applications of the proposed model-based ALC
inversion methodology. In particular, our model simulations were compared to
backscatter and extinction coefficients independently retrieved by Raman
lidar systems operating at different continental sites within the European
Aerosol Research Lidar Network (EARLINET). This comparison shows good
model–measurement agreement, with LR discrepancies below 20 %. The
model-assisted quantitative retrieval of both aerosol extinction and volume
was then tested using raw data from three different ALCs systems
(CHM 15k Nimbus), operating within the Italian Automated LIdar-CEilometer
network (ALICEnet). For this purpose, a 1-year record of the ALC-derived
aerosol optical thickness (AOT) at each site was compared to direct AOT
measurements performed by colocated sun–sky photometers. This comparison
shows an overall AOT agreement within 30 % at all sites. At one site, the
model-assisted ALC estimation of the aerosol volume and mass (i.e.,
PM10) in the lowermost levels was compared to values measured at
the surface level by colocated in situ instrumentation. Within this
exercise, the ALC-derived daily-mean mass concentration was found to
reproduce the corresponding (EU regulated) PM10 values measured by
the local air quality agency well in terms of both temporal variability and
absolute values. Although limited in space and time, the good performances of
the proposed approach suggest it could possibly
represent a valid option to extend the capabilities of ALCs to provide
quantitative information for operational air quality and meteorological
monitoring
Search for an invisibly decaying Higgs boson in e^+e^- collisions at \sqrt{s} = 183 - 189 GeV
A search for a Higgs boson decaying into invisible particles is performed
using the data collected at LEP by the L3 experiment at centre-of-mass energies
of 183 GeV and 189 GeV. The integrated luminosities are respectively 55.3 pb^-1
and 176.4 pb^-1. The observed candidates are consistent with the expectations
from Standard Model processes. In the hypothesis that the production cross
section of this Higgs boson equals the Standard Model one and the branching
ratio into invisible particles is 100%, a lower mass limit of 89.2 GeV is set
at 95% confidence level
Search for Extra Dimensions in Boson and Fermion Pair Production in e+e- Interactions at LEP
Extra spatial dimensions are proposed by recent theories that postulate the
scale of gravity to be of the same order as the electroweak scale. A sizeable
interaction between gravitons and Standard Model particles is then predicted.
Effects of these new interactions in boson and fermion pair production are
searched for in the data sample collected at centre-of-mass energies above the
Z pole by the L3 detector at LEP. In addition, the direct production of a
graviton associated with a Z boson is investigated. No statistically
significant hints for the existence of these effects are found and lower limits
in excess of 1 TeV are derived on the scale of this new theory of gravity
Search for Second-Generation Scalar Leptoquarks in Collisions at =1.96 TeV
Results on a search for pair production of second generation scalar
leptoquark in collisions at =1.96 TeV are reported. The
data analyzed were collected by the CDF detector during the 2002-2003 Tevatron
Run II and correspond to an integrated luminosity of 198 pb. Leptoquarks
(LQ) are sought through their decay into (charged) leptons and quarks, with
final state signatures represented by two muons and jets and one muon, large
transverse missing energy and jets. We observe no evidence for production
and derive 95% C.L. upper limits on the production cross sections as well
as lower limits on their mass as a function of , where is the
branching fraction for .Comment: 9 pages (3 author list) 5 figure
Search for Manifestations of New Physics in Fermion-Pair Production at LEP
The measurements of hadron and lepton-pair production cross sections and
leptonic forward-backward asymmetries performed with the L3 detector at
centre-of-mass energies between 130 GeV and 189 GeV are used to search for new
physics phenomena such as: contact interactions, exchange of virtual
leptoquarks, scalar quarks and scalar neutrinos, effects of TeV strings in
models of quantum gravity with large extra dimensions and non-zero sizes of the
fermions. No evidence for these phenomena is found and new limits on their
parameters are set
Measurement of Hadron and Lepton-Pair Production at 130GeV < \sqrt{s} < 189 GeV at LEP
We report on measurements of e+e- annihilation into hadrons and lepton pairs.
The data have been collected with the L3 detector at LEP at centre-of-mass
energies between 130 and 189 GeV. Using a total integrated luminosity of 243.7
pb^-1, 25864 hadronic and 8573 lepton-pair events are selected for the
measurement of cross sections and leptonic forward-backward asymmetries. The
results are in good agreement with Standard Model predictions
Measurement of the Tau Branching Fractions into Leptons
Using data collected with the L3 detector near the Z resonance, corresponding
to an integrated luminosity of 150pb-1, the branching fractions of the tau
lepton into electron and muon are measured to be
B(tau->e nu nu) = (17.806 +- 0.104 (stat.) +- 0.076 (syst.)) %,
B(tau->mu nu nu) = (17.342 +- 0.110 (stat.) +- 0.067 (syst.)) %.
From these results the ratio of the charged current coupling constants of the
muon and the electron is determined to be g_mu/g_e = 1.0007 +- 0.0051. Assuming
electron-muon universality, the Fermi constant is measured in tau lepton decays
as G_F = (1.1616 +- 0.0058) 10^{-5} GeV^{-2}. Furthermore, the coupling
constant of the strong interaction at the tau mass scale is obtained as
alpha_s(m_tau^2) = 0.322 +- 0.009 (exp.) +- 0.015 (theory)
Formation of the in Two-Photon Collisions at LEP
The two-photon width of the meson has been
measured with the L3 detector at LEP. The is studied in the decay
modes , KK, KK,
KK, , , and
using an integrated luminosity of 140 pb at GeV and
of 52 pb at GeV. The result is
(BR) keV. The dependence of the cross section is studied for
GeV. It is found to be better described by a Vector Meson
Dominance model form factor with a J-pole than with a -pole. In addition,
a signal of events is observed at the mass. Upper limits
for the two-photon widths of the , , and are also
given
Measurement of the ttbar Production Cross Section in ppbar Collisions at sqrt(s) = 1.96 TeV
We present a measurement of the top quark pair production cross section in
ppbar collisions at sqrt(s)=1.96 TeV using 318 pb^{-1} of data collected with
the Collider Detector at Fermilab. We select ttbar decays into the final states
e nu + jets and mu nu + jets, in which at least one b quark from the t-quark
decays is identified using a secondary vertex-finding algorithm. Assuming a top
quark mass of 178 GeV/c^2, we measure a cross section of 8.7 +-0.9 (stat)
+1.1-0.9 (syst) pb. We also report the first observation of ttbar with
significance greater than 5 sigma in the subsample in which both b quarks are
identified, corresponding to a cross section of 10.1 +1.6-1.4(stat)+2.0-1.3
(syst) pb.Comment: Accepted for publication in Physics Review Letters, 7 page
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