91 research outputs found
Digital Signal Processing
Contains an introduction and reports on fifteen research projects.National Science Foundation FellowshipU.S. Navy - Office of Naval Research (Contract N00014-81-K-0742)National Science Foundation (Grant ECS 84-07285)Sanders Associates, Inc.U.S. Air Force - Office of Scientific Research (Contract F19628-85-K-0028)AT&T Bell Laboratories Doctoral Support ProgramCanada, Bell Northern Research ScholarshipCanada, Fonds pour la Formation de Chercheurs et /'Aide a la Recherche Postgraduate FellowshipCanada, Natural Science and Engineering Research Council Postgraduate FellowshipAmoco Foundation FellowshipFannie and John Hertz Foundation Fellowshi
Digital Signal Processing
Contains an introduction and reports on twenty research projects.National Science Foundation (Grant ECS 84-07285)U.S. Navy - Office of Naval Research (Contract N00014-81-K-0742)National Science Foundation FellowshipSanders Associates, Inc.U.S. Air Force - Office of Scientific Research (Contract F19628-85-K-0028)Canada, Bell Northern Research ScholarshipCanada, Fonds pour la Formation de Chercheurs et l'Aide a la Recherche Postgraduate FellowshipCanada, Natural Science and Engineering Research Council Postgraduate FellowshipU.S. Navy - Office of Naval Research (Contract N00014-81-K-0472)Fanny and John Hertz Foundation FellowshipCenter for Advanced Television StudiesAmoco Foundation FellowshipU.S. Air Force - Office of Scientific Research (Contract F19628-85-K-0028
Functional sex differences in human primary auditory cortex
Background We used PET to study cortical activation during auditory stimulation and found sex differences in the human primary auditory cortex (PAC). Regional cerebral blood flow (rCBF) was measured in 10 male and 10 female volunteers while listening to sounds (music or white noise) and during a baseline (no auditory stimulation). Results and discussion We found a sex difference in activation of the left and right PAC when comparing music to noise. The PAC was more activated by music than by noise in both men and women. But this difference between the two stimuli was significantly higher in men than in women. To investigate whether this difference could be attributed to either music or noise, we compared both stimuli with the baseline and revealed that noise gave a significantly higher activation in the female PAC than in the male PAC. Moreover, the male group showed a deactivation in the right prefrontal cortex when comparing noise to the baseline, which was not present in the female group. Interestingly, the auditory and prefrontal regions are anatomically and functionally linked and the prefrontal cortex is known to be engaged in auditory tasks that involve sustained or selective auditory attention. Thus we hypothesize that differences in attention result in a different deactivation of the right prefrontal cortex, which in turn modulates the activation of the PAC and thus explains the sex differences found in the activation of the PAC. Conclusion Our results suggest that sex is an important factor in auditory brain studies
Broca's Region: Novel Organizational Principles and Multiple Receptor Mapping
A novel map of Broca's language region is proposed based on transmitter receptor distributions as functionally relevant molecular markers. It sheds new light on the relation between anatomy and functional segregation
Measurement of and binding energy in Au+Au collisions at = 3 GeV
Measurements of mass and binding energy of and
in Au+Au collisions at GeV are
presented, with an aim to address the charge symmetry breaking (CSB) problem in
hypernuclei systems with atomic number A = 4. The binding energies
are measured to be MeV and MeV for and , respectively. The measured binding-energy difference
is MeV for ground states. Combined with
the -ray transition energies, the binding-energy difference for excited
states is MeV, which is negative and
comparable to the value of the ground states within uncertainties. These new
measurements on the binding-energy difference in A = 4 hypernuclei
systems are consistent with the theoretical calculations that result in
and present a new method for the study of CSB effect using relativistic
heavy-ion collisions.Comment: 8 pages, 5 figure
Tomography of Ultra-relativistic Nuclei with Polarized Photon-gluon Collisions
A linearly polarized photon can be quantized from the Lorentz-boosted
electromagnetic field of a nucleus traveling at ultra-relativistic speed. When
two relativistic heavy nuclei pass one another at a distance of a few nuclear
radii, the photon from one nucleus may interact through a virtual
quark-antiquark pair with gluons from the other nucleus forming a short-lived
vector meson (e.g. ). In this experiment, the polarization was
utilized in diffractive photoproduction to observe a unique spin interference
pattern in the angular distribution of decays.
The observed interference is a result of an overlap of two wave functions at a
distance an order of magnitude larger than the travel distance
within its lifetime. The strong-interaction nuclear radii were extracted from
these diffractive interactions, and found to be fm () and fm (), larger than the nuclear charge
radii. The observable is demonstrated to be sensitive to the nuclear geometry
and quantum interference of non-identical particles
Search for the chiral magnetic effect via charge-dependent azimuthal correlations relative to spectator and participant planes in Au+Au collisions at = 200 GeV
The chiral magnetic effect (CME) refers to charge separation along a strong
magnetic field due to imbalanced chirality of quarks in local parity and
charge-parity violating domains in quantum chromodynamics. The experimental
measurement of the charge separation is made difficult by the presence of a
major background from elliptic azimuthal anisotropy. This background and the
CME signal have different sensitivities to the spectator and participant
planes, and could thus be determined by measurements with respect to these
planes. We report such measurements in Au+Au collisions at a nucleon-nucleon
center-of-mass energy of 200 GeV at the Relativistic Heavy-Ion Collider. It is
found that the charge separation, with the flow background removed, is
consistent with zero in peripheral (large impact parameter) collisions. Some
indication of finite CME signals is seen with a significance of 1--3 standard
deviations in mid-central (intermediate impact parameter) collisions.
Significant residual background effects may, however, still be present.Comment: 8 pages, 3 figure
Observation of Global Spin Alignment of and Vector Mesons in Nuclear Collisions
The strong force, as one of the four fundamental forces at work in the
universe, governs interactions of quarks and gluons, and binds together the
atomic nucleus. Notwithstanding decades of progress since Yukawa first
developed a description of the force between nucleons in terms of meson
exchange, a full understanding of the strong interaction remains a major
challenge in modern science. One remaining difficulty arises from the
non-perturbative nature of the strong force, which leads to the phenomenon of
quark confinement at distance scales on the order of the size of the proton.
Here we show that in relativistic heavy-ion collisions, where quarks and gluons
are set free over an extended volume, two species of produced vector (spin-1)
mesons, namely and , emerge with a surprising pattern of global
spin alignment. In particular, the global spin alignment for is
unexpectedly large, while that for is consistent with zero. The
observed spin-alignment pattern and magnitude for the cannot be
explained by conventional mechanisms, while a model with strong force fields
accommodates the current data. This is the first time that the strong force
field is experimentally supported as a key mechanism that leads to global spin
alignment. We extract a quantity proportional to the intensity of the field of
the strong force. Within the framework of the Standard Model, where the strong
force is typically described in the quark and gluon language of Quantum
Chromodynamics, the field being considered here is an effective proxy
description. This is a qualitatively new class of measurement, which opens a
new avenue for studying the behaviour of strong force fields via their imprint
on spin alignment
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