380 research outputs found
Spatial Attention Interacts With Serial-Order Retrieval From Verbal Working Memory
The ability to maintain the serial order of events is recognized as a major function of working memory. Although general models of working memory postulate a close link between working memory and attention, such a link has so far not been proposed specifically for serial-order working memory. The present study provided the first empirical demonstration of a direct link between serial order in verbal working memory and spatial selective attention. We show that the retrieval of later items of a sequence stored in working memory-compared with that of earlier items-produces covert attentional shifts toward the right. This observation suggests the conceptually surprising notion that serial-order working memory, even for nonspatially defined verbal items, draws on spatial attention. © The Author(s) 2013.Peer reviewe
Measurement of the rate of nu_e + d --> p + p + e^- interactions produced by 8B solar neutrinos at the Sudbury Neutrino Observatory
Solar neutrinos from the decay of B have been detected at the Sudbury
Neutrino Observatory (SNO) via the charged current (CC) reaction on deuterium
and by the elastic scattering (ES) of electrons. The CC reaction is sensitive
exclusively to nu_e's, while the ES reaction also has a small sensitivity to
nu_mu's and nu_tau's. The flux of nu_e's from ^8B decay measured by the CC
reaction rate is
\phi^CC(nu_e) = 1.75 +/- 0.07 (stat)+0.12/-0.11 (sys.) +/- 0.05(theor) x 10^6
/cm^2 s.
Assuming no flavor transformation, the flux inferred from the ES reaction
rate is
\phi^ES(nu_x) = 2.39+/-0.34 (stat.)+0.16}/-0.14 (sys) x 10^6 /cm^2 s.
Comparison of \phi^CC(nu_e) to the Super-Kamiokande Collaboration's precision
value of \phi^ES(\nu_x) yields a 3.3 sigma difference, providing evidence that
there is a non-electron flavor active neutrino component in the solar flux. The
total flux of active ^8B neutrinos is thus determined to be 5.44 +/-0.99 x
10^6/cm^2 s, in close agreement with the predictions of solar models.Comment: 6 pages (LaTex), 3 figures, submitted to Phys. Rev. Letter
Electron Antineutrino Search at the Sudbury Neutrino Observatory
Upper limits on the \nuebar flux at the Sudbury Neutrino Observatory have
been set based on the \nuebar charged-current reaction on deuterium. The
reaction produces a positron and two neutrons in coincidence. This distinctive
signature allows a search with very low background for \nuebar's from the Sun
and other potential sources. Both differential and integral limits on the
\nuebar flux have been placed in the energy range from 4 -- 14.8 MeV. For an
energy-independent \nu_e --> \nuebar conversion mechanism, the integral limit
on the flux of solar \nuebar's in the energy range from 4 -- 14.8 MeV is found
to be \Phi_\nuebar <= 3.4 x 10^4 cm^{-2} s^{-1} (90% C.L.), which corresponds
to 0.81% of the standard solar model 8B \nu_e flux of 5.05 x 10^6 cm^{-2}
s^{-1}, and is consistent with the more sensitive limit from KamLAND in the 8.3
-- 14.8 MeV range of 3.7 x 10^2 cm^{-2} s^{-1} (90% C.L.). In the energy range
from 4 -- 8 MeV, a search for \nuebar's is conducted using coincidences in
which only the two neutrons are detected. Assuming a \nuebar spectrum for the
neutron induced fission of naturally occurring elements, a flux limit of
Phi_\nuebar <= 2.0 x 10^6 cm^{-2} s^{-1}(90% C.L.) is obtained.Comment: submitted to Phys. Rev.
Measurement of the Total Active 8B Solar Neutrino Flux at the Sudbury Neutrino Observatory with Enhanced Neutral Current Sensitivity
The Sudbury Neutrino Observatory (SNO) has precisely determined the total
active (nu_x) 8B solar neutrino flux without assumptions about the energy
dependence of the nu_e survival probability. The measurements were made with
dissolved NaCl in the heavy water to enhance the sensitivity and signature for
neutral-current interactions. The flux is found to be 5.21 +/- 0.27 (stat) +/-
0.38 (syst) x10^6 cm^{-2}s^{-1}, in agreement with previous measurements and
standard solar models. A global analysis of these and other solar and reactor
neutrino results yields Delta m^{2} = 7.1^{+1.2}_{-0.6}x10^{-5} ev^2 and theta
= 32.5^{+2.4}_{-2.3} degrees. Maximal mixing is rejected at the equivalent of
5.4 standard deviations.Comment: Submitted to Phys. Rev. Let
Combined Analysis of all Three Phases of Solar Neutrino Data from the Sudbury Neutrino Observatory
We report results from a combined analysis of solar neutrino data from all
phases of the Sudbury Neutrino Observatory. By exploiting particle
identification information obtained from the proportional counters installed
during the third phase, this analysis improved background rejection in that
phase of the experiment. The combined analysis resulted in a total flux of
active neutrino flavors from 8B decays in the Sun of (5.25 \pm
0.16(stat.)+0.11-0.13(syst.))\times10^6 cm^{-2}s^{-1}. A two-flavor neutrino
oscillation analysis yielded \Deltam^2_{21} = (5.6^{+1.9}_{-1.4})\times10^{-5}
eV^2 and tan^2{\theta}_{12}= 0.427^{+0.033}_{-0.029}. A three-flavor neutrino
oscillation analysis combining this result with results of all other solar
neutrino experiments and the KamLAND experiment yielded \Deltam^2_{21} =
(7.41^{+0.21}_{-0.19})\times10^{-5} eV^2, tan^2{\theta}_{12} =
0.446^{+0.030}_{-0.029}, and sin^2{\theta}_{13} =
(2.5^{+1.8}_{-1.5})\times10^{-2}. This implied an upper bound of
sin^2{\theta}_{13} < 0.053 at the 95% confidence level (C.L.)
Low Multiplicity Burst Search at the Sudbury Neutrino Observatory
Results are reported from a search for low-multiplicity neutrino bursts in
the Sudbury Neutrino Observatory (SNO). Such bursts could indicate detection of
a nearby core-collapse supernova explosion. The data were taken from Phase I
(November 1999 - May 2001), when the detector was filled with heavy water, and
Phase II (July 2001 - August 2003), when NaCl was added to the target. The
search was a blind analysis in which the potential backgrounds were estimated
and analysis cuts were developed to eliminate such backgrounds with 90%
confidence before the data were examined. The search maintained a greater than
50% detection probability for standard supernovae occurring at a distance of up
to 60 kpc for Phase I and up to 70 kpc for Phase II. No low-multiplicity bursts
were observed during the data-taking period.Comment: 11 pages, 4 figures, submitted to Ap
Contemporary climate change and terrestrial invertebrates:Evolutionary versus plastic changes
To forecast the responses of species to future climate change, an understanding of the ability of species to adapt to long-term shifts in temperature is crucial. We present a review on evolutionary adaptation and phenotypic plasticity of temperature-related traits in terrestrial invertebrates. The evidence for adaptive evolution in melanization is good, but we caution that genetic determination needs to be tested in each individual species, and complex genetic correlations may exist. For phenological traits allochronic data sets provide powerful means to track climate-induced changes; however, rarely are responses deconstructed into evolutionary and plastic responses. Laboratory studies suggest climate change responses in these traits will be driven by both. For stress resistance, the evidence for shifts in traits is poor. Studies leaning heavily on Drosophila have demonstrated potential limits to evolutionary responses in desiccation and heat resistance. Quantifying the capacity for these species to respond plastically and extending this work to other taxa will be an important next step. We also note that, although not strictly speaking a species trait, the response of endosymbionts to heat stress requires further study. Finally, while clearly genetic, and possibly adaptive, the anonymous nature of latitudinal shifts in clines of genetic markers in Drosophila prevents further interpretation
A Search for Neutrinos from the Solar hep Reaction and the Diffuse Supernova Neutrino Background with the Sudbury Neutrino Observatory
A search has been made for neutrinos from the hep reaction in the Sun and from the diffus
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