109 research outputs found
How the Supply of Fake News Affected Consumer Behavior during the 2016 US Election
We characterize the effect of fake news on online browsing during the 2016 US presidential election. We estimate that weekday increases of 10 fake news articles — that were confirmed to be false by third-party services — increased the incidence of fake news site visits by 3.0%. To address endogeneity, we employ two approaches that attempt to isolate exogenous variation in fake news supply. We also estimate that weekday 10-article increases in fake news increase the odds of visiting one or more fake news sites by 3.7%. Overall, this evidence demonstrates the effectiveness of fake news production in reaching a diverse set of consumers
Water in society: An interdisciplinary course to support undergraduate students\u27 water literacy
Parton energy loss limits and shadowing in Drell-Yan dimuon production
A precise measurement of the ratios of the Drell-Yan cross section per
nucleon for an 800 GeV/c proton beam incident on Be, Fe and W targets is
reported. The behavior of the Drell-Yan ratios at small target parton momentum
fraction is well described by an existing fit to the shadowing observed in
deep-inelastic scattering. The cross section ratios as a function of the
incident parton momentum fraction set tight limits on the energy loss of quarks
passing through a cold nucleus
Measurement of Angular Distributions of Drell-Yan Dimuons in Interactions at 800 GeV/c
We report a measurement of the angular distributions of Drell-Yan dimuons
produced using an 800 GeV/c proton beam on a hydrogen target. The polar and
azimuthal angular distribution parameters have been extracted over the
kinematic range GeV/c (excluding the
resonance region), GeV/c, and . The angular
distributions are similar to those of , and both data sets are compared
with models which attribute the distribution either to the
presence of the transverse-momentum-dependent Boer-Mulders structure function
or to QCD effects. The data indicate the presence of both
mechanisms. The validity of the Lam-Tung relation in Drell-Yan is also
tested.Comment: 4 pages, 3 figure
Measurement of Angular Distributions of Drell-Yan Dimuons in p + d Interaction at 800 GeV/c
We report a measurement of the angular distributions of Drell-Yan dimuons
produced using an 800 GeV/c proton beam on a deuterium target. The muon angular
distributions in polar angle and azimuthal angle have been
measured over the kinematic range GeV/c, GeV/c, and . No significant cos dependence is found
in these proton-induced Drell-Yan data, in contrast to the situation for
pion-induced Drell-Yan. The data are compared with expectations from models
which attribute the cos distribution to a QCD vacuum effect or to the
presence of the transverse-momentum-dependent Boer-Mulders structure function
. Constraints on the magnitude of the sea-quark
structure functions are obtained.Comment: 4 pages, 3 figure
Effect of treatment of gestational diabetes mellitus on pregnancy outcomes
Copyright © 2005 Massachusetts Medical Society.Background: We conducted a randomized clinical trial to determine whether treatment of women with gestational diabetes mellitus reduced the risk of perinatal complications. Methods: We randomly assigned women between 24 and 34 weeks’ gestation who had gestational diabetes to receive dietary advice, blood glucose monitoring, and insulin therapy as needed (the intervention group) or routine care. Primary outcomes included serious perinatal complications (defined as death, shoulder dystocia, bone fracture, and nerve palsy), admission to the neonatal nursery, jaundice requiring phototherapy, induction of labor, cesarean birth, and maternal anxiety, depression, and health status. Results: The rate of serious perinatal complications was significantly lower among the infants of the 490 women in the intervention group than among the infants of the 510 women in the routine-care group (1 percent vs. 4 percent; relative risk adjusted for maternal age, race or ethnic group, and parity, 0.33; 95 percent confidence interval, 0.14 to 0.75; P=0.01). However, more infants of women in the intervention group were admitted to the neonatal nursery (71 percent vs. 61 percent; adjusted relative risk, 1.13; 95 percent confidence interval, 1.03 to 1.23; P=0.01). Women in the intervention group had a higher rate of induction of labor than the women in the routine-care group (39 percent vs. 29 percent; adjusted relative risk, 1.36; 95 percent confidence interval, 1.15 to 1.62; P<0.001), although the rates of cesarean delivery were similar (31 percent and 32 percent, respectively; adjusted relative risk, 0.97; 95 percent confidence interval, 0.81 to 1.16; P=0.73). At three months post partum, data on the women’s mood and quality of life, available for 573 women, revealed lower rates of depression and higher scores, consistent with improved health status, in the intervention group. Conclusions: Treatment of gestational diabetes reduces serious perinatal morbidity and may also improve the woman’s health-related quality of life.Caroline A. Crowther, Janet E. Hiller, John R. Moss, Andrew J. McPhee, William S. Jeffries and Jeffrey S. Robinso
dbar/ubar Asymmetry and the Origin of the Nucleon Sea
The Drell-Yan cross section ratios, , measured in
Fermilab E866, have led to the first determination of ,
, and the integral of for the
proton over the range . The E866 results are compared
with predictions based on parton distribution functions and various theoretical
models. The relationship between the E866 results and the NMC measurement of
the Gottfried integral is discussed. The agreement between the E866 results and
models employing virtual mesons indicates these non-perturbative processes play
an important role in the origin of the , asymmetry in the
nucleon sea.Comment: 5 pages, 3 figures, ReVTe
Measurement of the Light Antiquark Flavor Asymmetry in the Nucleon Sea
A precise measurement of the ratio of Drell-Yan yields from an 800 GeV/c
proton beam incident on hydrogen and deuterium targets is reported. Over
140,000 Drell-Yan muon pairs with dimuon mass M_{mu+ mu-} >= 4.5 GeV/c^2 were
recorded. From these data, the ratio of anti-down (dbar) to anti-up (ubar)
quark distributions in the proton sea is determined over a wide range in
Bjorken-x. A strong x dependence is observed in the ratio dbar/ubar, showing
substantial enhancement of dbar with respect to ubar for x<0.2. This result is
in fair agreement with recent parton distribution parameterizations of the sea.
For x>0.2, the observed dbar/ubar ratio is much nearer unity than given by the
parameterizations.Comment: REVTeX, to be published in Phys. Rev. Let
- …