3,484 research outputs found
Suppression of the 2010 Alexandrium fundyense bloom by changes in physical, biological, and chemical properties of the Gulf of Maine
Author Posting. © American Society of Limnology and Oceanography, 2011. This article is posted here by permission of American Society of Limnology and Oceanography for personal use, not for redistribution. The definitive version was published in Limnology and Oceanography 56 (2011): 2411-2426, doi:10.4319/lo.2011.56.6.2411.For the period 2005–2009, the abundance of resting cysts in bottom sediments from the preceding autumn was a first-order predictor of the overall severity of spring–summer blooms of Alexandrium fundyense in the western Gulf of Maine and southern New England. Cyst abundance off mid-coast Maine was significantly higher in autumn 2009 than it was preceding a major regional bloom in 2005. A seasonal ensemble forecast was computed using a range of forcing conditions for the period 2004–2009, suggesting that a large bloom was likely in the western Gulf of Maine in 2010. This did not materialize, perhaps because environmental conditions in spring–summer 2010 were not favorable for growth of A. fundyense. Water mass anomalies indicate a regional-scale change in circulation with direct influence on A. fundyense's niche. Specifically, near-surface waters were warmer, fresher, more stratified, and had lower nutrients than during the period of observations used to construct the ensemble forecast. Moreover, a weaker-than-normal coastal current lessened A. fundyense transport into the western Gulf of Maine and Massachusetts Bay. Satellite ocean color observations indicate the 2010 spring phytoplankton bloom was more intense than usual. Early season nutrient depletion may have caused a temporal mismatch with A. fundyense's endogenous clock that regulates the timing of cyst germination. These findings highlight the difficulties of ecological forecasting in a changing oceanographic environment, and underscore the need for a sustained observational network to drive such forecasts.We gratefully acknowledge support of the National Oceanic
Atmospheric Administration (grant NA06NOS4780245 for the
Gulf of Maine Toxicity (GOMTOX) program) and the Woods
Hole Center for Oceans and Human Health through National
Science Foundation grants OCE-0430724 and OCE-0911031 and
National Institute of Environmental Health Sciences grant 1P50-
ES01274201
Climatic Variability of the Circulation in the Rhode Island Sound: A Modeling Study
Seasonal and interannual variability of the circulation in the Rhode Island Sound (RIS) is investigated by employing the Regional Ocean Modeling System (ROMS) with two configurations in which a local-scale model with very fine resolution over the RIS is nested within a regional-scale model covering the entire US Northeastern Continental Shelf. The models are driven by tidal harmonics, climatological river discharge, and realistic ocean open boundary conditions and atmospheric forcing from January 2004 to December 2009. Results show that the tidal residual current forms a cyclonic circulation in the RIS, with amplitude of a few centimeters per second. During summer, the cyclonic circulation is significantly strengthened owing to tidal mixing and local stratification. However, due to strong northwesterly winds in winter, the cyclonic circulation disappears and instead the surface currents in the RIS move offshore. Simulations further indicate that the RIS winter currents, in terms of their magnitude and direction, have interannual variability that appears to be related to the North Atlantic Oscillation (NAO) winter index. In addition, the southwestward jet near the southern New England shelf break is found to intensify (weaken) during the low (high) phases of the NAO with a lag of about 1 year. The ROMS models are also used to examine the response of the regional ocean circulation to global warming, with both atmospheric forcing and open boundary conditions obtained from global climate model outputs. As the climate warms, it is found that the cyclonic gyre in the RIS is intensified, and this change is due to an intensification of the larger-scale cyclonic coastal ocean circulation over the Middle Atlantic Bight in a warming climate
Determination of the D0 -> K+pi- Relative Strong Phase Using Quantum-Correlated Measurements in e+e- -> D0 D0bar at CLEO
We exploit the quantum coherence between pair-produced D0 and D0bar in
psi(3770) decays to study charm mixing, which is characterized by the
parameters x and y, and to make a first determination of the relative strong
phase \delta between doubly Cabibbo-suppressed D0 -> K+pi- and Cabibbo-favored
D0bar -> K+pi-. We analyze a sample of 1.0 million D0D0bar pairs from 281 pb^-1
of e+e- collision data collected with the CLEO-c detector at E_cm = 3.77 GeV.
By combining CLEO-c measurements with branching fraction input and
time-integrated measurements of R_M = (x^2+y^2)/2 and R_{WS} = Gamma(D0 ->
K+pi-)/Gamma(D0bar -> K+pi-) from other experiments, we find \cos\delta = 1.03
+0.31-0.17 +- 0.06, where the uncertainties are statistical and systematic,
respectively. In addition, by further including external measurements of charm
mixing parameters, we obtain an alternate measurement of \cos\delta = 1.10 +-
0.35 +- 0.07, as well as x\sin\delta = (4.4 +2.7-1.8 +- 2.9) x 10^-3 and \delta
= 22 +11-12 +9-11 degrees.Comment: 37 pages, also available through
http://www.lns.cornell.edu/public/CLNS/2007/. Incorporated referee's comment
Updated Measurement of the Strong Phase in D0 --> K+pi- Decay Using Quantum Correlations in e+e- --> D0 D0bar at CLEO
We analyze a sample of 3 million quantum-correlated D0 D0bar pairs from 818
pb^-1 of e+e- collision data collected with the CLEO-c detector at E_cm = 3.77
GeV, to give an updated measurement of \cos\delta and a first determination of
\sin\delta, where \delta is the relative strong phase between doubly
Cabibbo-suppressed D0 --> K+pi- and Cabibbo-favored D0bar --> K+pi- decay
amplitudes. With no inputs from other experiments, we find \cos\delta = 0.81
+0.22+0.07 -0.18-0.05, \sin\delta = -0.01 +- 0.41 +- 0.04, and |\delta| = 10
+28+13 -53-0 degrees. By including external measurements of mixing parameters,
we find alternative values of \cos\delta = 1.15 +0.19+0.00 -0.17-0.08,
\sin\delta = 0.56 +0.32+0.21 -0.31-0.20, and \delta = (18 +11-17) degrees. Our
results can be used to improve the world average uncertainty on the mixing
parameter y by approximately 10%.Comment: Minor revisions, version accepted by PR
Dalitz Plot Analysis of Ds to K+K-pi+
We perform a Dalitz plot analysis of the decay Ds to K+K-pi+ with the CLEO-c
data set of 586/pb of e+e- collisions accumulated at sqrt(s) = 4.17 GeV. This
corresponds to about 0.57 million D_s+D_s(*)- pairs from which we select 14400
candidates with a background of roughly 15%. In contrast to previous
measurements we find good agreement with our data only by including an
additional f_0(1370)pi+ contribution. We measure the magnitude, phase, and fit
fraction of K*(892) K+, phi(1020)pi+, K0*(1430)K+, f_0(980)pi+, f_0(1710)pi+,
and f_0(1370)pi+ contributions and limit the possible contributions of other KK
and Kpi resonances that could appear in this decay.Comment: 21 Pages,available through http://www.lns.cornell.edu/public/CLNS/,
submitted to PR
Search for D0 to p e- and D0 to pbar e+
Using data recorded by CLEO-c detector at CESR, we search for simultaneous
baryon and lepton number violating decays of the D^0 meson, specifically, D^0
--> p-bar e^+, D^0-bar --> p-bar e^+, D^0 --> p e^- and D^0-bar --> p e^-. We
set the following branching fraction upper limits: D^0 --> p-bar e^+ (D^0-bar
--> p-bar e^+) p e^- (D^0-bar --> p e^-) < 1.2 *
10^{-5}, both at 90% confidence level.Comment: 10 pages, available through http://www.lns.cornell.edu/public/CLNS/,
submitted to PRD. Comments: changed abstract, added reference for section 1,
vertical axis in Fig.5 changed (starts from 1.5 rather than 2.0), fixed typo
Charmonium decays to gamma pi0, gamma eta, and gamma eta'
Using data acquired with the CLEO-c detector at the CESR e+e- collider, we
measure branching fractions for J/psi, psi(2S), and psi(3770) decays to gamma
pi0, gamma eta, and gamma eta'. Defining R_n = B[ psi(nS)-->gamma eta ]/B[
psi(nS)-->gamma eta' ], we obtain R_1 = (21.1 +- 0.9)% and, unexpectedly, an
order of magnitude smaller limit, R_2 < 1.8% at 90% C.L. We also use
J/psi-->gamma eta' events to determine branching fractions of improved
precision for the five most copious eta' decay modes.Comment: 14 pages, available through http://www.lns.cornell.edu/public/CLNS/,
published in Physical Review
Precision Measurement of the Mass of the h_c(1P1) State of Charmonium
A precision measurement of the mass of the h_c(1P1) state of charmonium has
been made using a sample of 24.5 million psi(2S) events produced in e+e-
annihilation at CESR. The reaction used was psi(2S) -> pi0 h_c, pi0 -> gamma
gamma, h_c -> gamma eta_c, and the reaction products were detected in the
CLEO-c detector.
Data have been analyzed both for the inclusive reaction and for the exclusive
reactions in which eta_c decays are reconstructed in fifteen hadronic decay
channels. Consistent results are obtained in the two analyses. The averaged
results of the present measurements are M(h_c)=3525.28+-0.19 (stat)+-0.12(syst)
MeV, and B(psi(2S) -> pi0 h_c)xB(h_c -> gamma eta_c)= (4.19+-0.32+-0.45)x10^-4.
Using the 3PJ centroid mass, Delta M_hf(1P)= - M(h_c) =
+0.02+-0.19+-0.13 MeV.Comment: 9 pages, available through http://www.lns.cornell.edu/public/CLNS/,
submitted to PR
Precision Measurement of B(D+ -> mu+ nu) and the Pseudoscalar Decay Constant fD+
We measure the branching ratio of the purely leptonic decay of the D+ meson
with unprecedented precision as B(D+ -> mu+ nu) = (3.82 +/- 0.32 +/-
0.09)x10^(-4), using 818/pb of data taken on the psi(3770) resonance with the
CLEO-c detector at the CESR collider. We use this determination to derive a
value for the pseudoscalar decay constant fD+, combining with measurements of
the D+ lifetime and assuming |Vcd| = |Vus|. We find fD+ = (205.8 +/- 8.5 +/-
2.5) MeV. The decay rate asymmetry [B(D+ -> mu+ nu)-B(D- -> mu- nu)]/[B(D+ ->
mu+ nu)+B(D- -> mu- nu)] = 0.08 +/- 0.08, consistent with no CP violation. We
also set 90% confidence level upper limits on B(D+ -> tau+ nu) < 1.2x10^(-3)
and B(D+ -> e+ nu) < 8.8x10^(-6).Comment: 24 pages, 11 figures and 6 tables, v2 replaced some figure vertical
axis scales, v3 corrections from PRD revie
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