6,045 research outputs found
Anosognosia in Amnestic Mild Cognitive Impairment is Related to Diminished Hippocampal Volume Comparable to Alzheimer's Disease Dementia:Preliminary MRI Findings
Although the presence of anosognosia in amnestic mild cognitive impairment (aMCI) may be predictive of conversion to Alzheimer’s disease (AD), little is known about its neural correlates in AD and aMCI. Four different groups were compared using volumetric and diffusion magnetic resonance imaging metrics in regions of interest (hippocampus and cingulum cortex gray matter, cingulum bundle white matter): aMCI subjects with anosognosia (n = 6), aMCI subjects without anosognosia (n = 12), AD subjects with anosognosia (n = 6), and AD subjects without anosognosia (n = 9). aMCI subjects with anosognosia displayed a significantly lower gray matter density (GMD) in the bilateral hippocampus than aMCI subjects without anosognosia, which was accounted for by bilateral hippocampal differences. Furthermore, we identified that the mean hippocampal gray matter density of aMCI subjects with anosognosia was not statistically different than that of AD subjects. The groups of aMCI and AD subjects with anosognosia also displayed a lower GMD in the bilateral cingulum cortex compared to subjects without anosognosia, but these differences were not statistically significant. No statistically significant differences were found in the fractional anisotropy or mean diffusivity of the hippocampus or cingulum between subjects with and without anosognosia in aMCI or AD groups. While these findings are derived from a small population of subjects and are in need of replication, they suggest that anosognosia in aMCI might be a useful clinical marker to suspect brain changes associated with AD neuropathology
A High Statistics Measurement of the Lambdac+ Lifetime
A high statistics measurement of the Lambdac+ lifetime from the Fermilab
fixed-target FOCUS photoproduction experiment is presented. We describe the
analysis technique with particular attention to the determination of the
systematic uncertainty. The measured value of 204.6 +/- 3.4 (stat.) +/- 2.5
(syst.) fs from 8034 +/- 122 Lambdac -> pKpi decays represents a significant
improvement over the present world average.Comment: Submitted to Physical Review Letter
Search for CP violation in D0 and D+ decays
A high statistics sample of photoproduced charm particles from the FOCUS
(E831) experiment at Fermilab has been used to search for CP violation in the
Cabibbo suppressed decay modes D+ to K-K+pi+, D0 to K-K+ and D0 to pi-pi+. We
have measured the following CP asymmetry parameters: A_CP(K-K+pi+) = +0.006 +/-
0.011 +/- 0.005, A_CP(K-K+) = -0.001 +/- 0.022 +/- 0.015 and A_CP(pi-pi+) =
+0.048 +/- 0.039 +/- 0.025 where the first error is statistical and the second
error is systematic. These asymmetries are consistent with zero with smaller
errors than previous measurements.Comment: 12 pages, 4 figure
Study of the D^0 \to pi^-pi^+pi^-pi^+ decay
Using data from the FOCUS (E831) experiment at Fermilab, we present new
measurements for the Cabibbo-suppressed decay mode . We measure the branching ratio .
An amplitude analysis has been performed, a first for this channel, in order to
determine the resonant substructure of this decay mode. The dominant component
is the decay , accounting for 60% of the decay rate.
The second most dominant contribution comes from the decay , with a fraction of 25%. We also study the
line shape and resonant substructure. Using the helicity formalism for the
angular distribution of the decay , we measure
a longitudinal polarization of %.Comment: 38 pages, 8 figures. accepted for publication in Physical Review
A Study of D0 --> K0(S) K0(S) X Decay Channels
Using data from the FOCUS experiment (FNAL-E831), we report on the decay of
mesons into final states containing more than one . We present
evidence for two Cabibbo favored decay modes, and
, and measure their combined branching fraction
relative to to be = 0.0106
0.0019 0.0010. Further, we report new measurements of
=
0.0179 0.0027 0.0026, = 0.0144 0.0032 0.0016,
and = 0.0208 0.0035 0.0021 where the first error is
statistical and the second is systematic.Comment: 11 pages, 3 figures, typos correcte
A measurement of lifetime differences in the neutral D-meson system
Using a high statistics sample of photoproduced charm particles from the
FOCUS experiment at Fermilab, we compare the lifetimes of neutral D mesons
decaying via D0 to K- pi+ and K- K+ to measure the lifetime differences between
CP even and CP odd final states. These measurements bear on the phenomenology
of D0 - D0bar mixing. If the D0 to K-pi+ is an equal mixture of CP even and CP
odd eigenstates, we measure yCP = 0.0342 \pm 0.0139 \pm 0.0074.Comment: 15 pages, 5 figure
Search for CP violation in D0 and D+ decays
A high statistics sample of photoproduced charm particles from the FOCUS
(E831) experiment at Fermilab has been used to search for CP violation in the
Cabibbo suppressed decay modes D+ to K-K+pi+, D0 to K-K+ and D0 to pi-pi+. We
have measured the following CP asymmetry parameters: A_CP(K-K+pi+) = +0.006 +/-
0.011 +/- 0.005, A_CP(K-K+) = -0.001 +/- 0.022 +/- 0.015 and A_CP(pi-pi+) =
+0.048 +/- 0.039 +/- 0.025 where the first error is statistical and the second
error is systematic. These asymmetries are consistent with zero with smaller
errors than previous measurements.Comment: 12 pages, 4 figure
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