969 research outputs found
Copper speciation in coastal rain and estuarine water
Copper exists in two oxidation states in natural waters, Cu(I) and Cu(II). Determining the speciation of copper rather than its total concentration is essential in order to assess the atmospheric reactivity and environmental fate of copper in the troposphere. The concentration and speciation of copper was determined in rainwater samples from Wilmington, North Carolina, from August 25, 2000 to September 24, 2002. Volume weighted average concentrations of Cutotal, Cu(I), and Cu(II) in rainwater were 5.3 nM, 1.4 nM, and 3.2 nM, respectively. An undetermined ligand may be stabilizing Cu(I) in authentic rainwater.
Rainwater Cu(II) concentrations were significantly higher in the summer, whereas Cu(I) concentrations were significantly higher in the winter. The calculated atmospheric flux of copper, 504 ”g m-2 yr-1, is in good agreement with the calculated copper flux at Florianopolis, Brazil and two Maryland Chesapeake Bay sites. Copper(I) and Cu(II) concentrations were not correlated with each other and Cu(II) concentrations did not correlate with any other rainwater analyte. Significant positive correlations were found between Cu(I) and DOC, SO42-, NO3-, and Fetotal. All copper species (Cu(I), Cu(II), Cutotal, Cuparticulate) showed an inverse correlation with rainfall amount. All copper species increased in concentration with decreasing rainwater pH. All copper species were higher for storms of continental origin versus storms of coastal origin. No diurnal variations were seen with Cu(I). However, Cu(II) concentrations had a maximum between 12 pm â 6 pm. It is possible that Fe oxyhydroxides with adsorbed Cu(II) undergo reactions that release Cu(II) in the presence of sunlight. Contamination by trace metals, such as copper, contributes to the degradation of estuarine systems in many areas, including North Carolina. Speciation, or the distribution of copper among its various chemical forms, controls the reactivity, toxicity, and bioavailability of the metal in estuarine sediments and water, as in rain. Estuarine water samples were collected and analyzed for Cu(I) during April, July, and November of 2001 and March 2002. The percentage of total copper as Cu(I) varied from 1.9% - 4.1% with an overall average of 3.4%. No flux of Cu(I) was observed into or out of the water overlying the estuarine sediments in controlled laboratory experiments. Almost the same amount of copper that enters the Cape Fear River estuary from atmospheric deposition (8.7 X 102 moles Cu/year) fluxes into the sediments (5.8 X 102 moles Cu/year)
Outlook and appraisal [June 1993]
First quarter GDP figures signal the end of the recession. Recent falls in unemployment and rising house prices should stimulate greater expenditure from consumers now that the threat of redundancy has receded
Special article : Quarterly Economic Commentary: Volume 10-18
The Fraser ofAllander Institute has, since its inception, sought to promote debate and research into the Scottish economy. One way in which we have done this is to publish, every quarter, a collection of views and results from those who conduct research in this area. In the current volume J McGilvray presents a review of the responses to the government's consultation paper on water and sewerage in Scotland. In previous volumes, a large number of articles appeared and addressed a wide variety of subjects. Articles which appeared in volumes 10 - 18 are documented on the following pages and those wishing to obtain backcopies can do so, through the Institute, by contacting the editor. Articles appear by volume & number and are labelled according to whether they were a Feature Article (FA), Briefing Paper (BP), Economic Perspective (EP) or a Special Article (SA
Search for the lepton-flavor-violating decays Bs0âe±Όâ and B0âe±Όâ
A search for the lepton-flavor-violating decays Bs0âe±Όâ and B0âe±Όâ is performed with a data sample, corresponding to an integrated luminosity of 1.0ââfb-1 of pp collisions at âs=7ââTeV, collected by the LHCb experiment. The observed number of Bs0âe±Όâ and B0âe±Όâ candidates is consistent with background expectations. Upper limits on the branching fractions of both decays are determined to be B(Bs0âe±Όâ)101ââTeV/c2 and MLQ(B0âe±Όâ)>126ââTeV/c2 at 95% C.L., and are a factor of 2 higher than the previous bounds
Observation of two new baryon resonances
Two structures are observed close to the kinematic threshold in the mass spectrum in a sample of proton-proton collision data, corresponding
to an integrated luminosity of 3.0 fb recorded by the LHCb experiment.
In the quark model, two baryonic resonances with quark content are
expected in this mass region: the spin-parity and
states, denoted and .
Interpreting the structures as these resonances, we measure the mass
differences and the width of the heavier state to be
MeV,
MeV,
MeV, where the first and second
uncertainties are statistical and systematic, respectively. The width of the
lighter state is consistent with zero, and we place an upper limit of
MeV at 95% confidence level. Relative
production rates of these states are also reported.Comment: 17 pages, 2 figure
Model-independent search for CP violation in D0âKâK+ÏâÏ+ and D0âÏâÏ+Ï+Ïâ decays
A search for CP violation in the phase-space structures of D0 and View the MathML source decays to the final states KâK+ÏâÏ+ and ÏâÏ+Ï+Ïâ is presented. The search is carried out with a data set corresponding to an integrated luminosity of 1.0 fbâ1 collected in 2011 by the LHCb experiment in pp collisions at a centre-of-mass energy of 7 TeV. For the KâK+ÏâÏ+ final state, the four-body phase space is divided into 32 bins, each bin with approximately 1800 decays. The p-value under the hypothesis of no CP violation is 9.1%, and in no bin is a CP asymmetry greater than 6.5% observed. The phase space of the ÏâÏ+Ï+Ïâ final state is partitioned into 128 bins, each bin with approximately 2500 decays. The p-value under the hypothesis of no CP violation is 41%, and in no bin is a CP asymmetry greater than 5.5% observed. All results are consistent with the hypothesis of no CP violation at the current sensitivity
Observation of the decay
The decay is observed for the first
time, using proton-proton collisions collected with the LHCb detector
corresponding to an integrated luminosity of 3fb. A signal yield of
decays is reported with a significance of 6.2 standard deviations.
The ratio of the branching fraction of \B_c \rightarrow J/\psi K^+ K^- \pi^+
decays to that of decays is measured to be
, where the first uncertainty is statistical and the
second is systematic.Comment: 18 pages, 2 figure
Observation of associated production of a boson with a meson in the~forward region
A search for associated production of a boson with an open charm meson is
presented using a data sample, corresponding to an integrated luminosity of
of proton--proton collisions at a centre-of-mass energy
of 7\,TeV, collected by the LHCb experiment. %% Seven candidate events for
associated production of a boson with a meson and four candidate
events for a boson with a meson are observed with a combined
significance of 5.1standard deviations. The production cross-sections in the
forward region are measured to be where the first uncertainty is statistical and the
second systematic.Comment: 18 pages, 2 figure
Observation of the decay B+câBÂșsÏ+
The result of a search for the decay B+câBÂșsÏ+ is presented, using the BÂșsâDs-Ï+ and BÂșsâJ/ÏÏ channels. The analysis is based on a data sample of pp collisions collected with the LHCb detector, corresponding to an integrated luminosity of 1ââfb-1 taken at a center-of-mass energy of 7 TeV, and 2ââfb-1 taken at 8 TeV. The decay B+câBÂșsÏ+ is observed with significance in excess of 5 standard deviations independently in both decay channels. The measured product of the ratio of cross sections and branching fraction is [Ï(Bc+)/Ï(BÂșs)]ĂB(Bc+âBÂșsÏ+)=[2.37±0.31â(stat)±0.11â(syst)-0.13+0.17(ÏBc+)]Ă10-3, in the pseudorapidity range 2<η(B)<5, where the first uncertainty is statistical, the second is systematic, and the third is due to the uncertainty on the Bc+ lifetime. This is the first observation of a B meson decaying to another B meson via the weak interaction
Measurements of the , , meson and baryon lifetimes
Measurements of -hadron lifetimes are reported using collision data,
corresponding to an integrated luminosity of 1.0fb, collected by the
LHCb detector at a centre-of-mass energy of Tev. Using the exclusive decays
, , ,
and the average decay
times in these modes are measured to be = 0.004 0.003 ps, =
0.006 0.004 ps, = 0.013
0.005 ps, = 0.027
0.006 ps and = 0.011
0.005 ps, where the first uncertainty is statistical and the second is
systematic. These represent the most precise lifetime measurements in these
decay modes. In addition, ratios of these lifetimes, and the ratio of the
decay-width difference, , to the average width, , in
the system, , are
reported. All quantities are found to be consistent with Standard Model
expectations.Comment: 28 pages, 4 figures. Updated reference
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