11,751 research outputs found
Electroweak Tests at Beta-beams
We explore the possibility of measuring the Weinberg angle from
(anti)neutrino-electron scattering using low energy beta beams, a method that
produces single flavour neutrino beams from the beta-decay of boosted
radioactive ions. We study how the sensitivity of a possible measurement
depends on the intensity of the ion beam and on a combination of different
Lorentz boosts of the ions.Comment: 10 pages, 6 figure
Time-Reversal Violating Schiff Moment of 225Ra
We use the Skyrme-Hartree-Fock method, allowing all symmetries to be broken,
to calculate the time-reversal-violating nuclear Schiff moment (which induces
atomic electric dipole moments) in the octupole-deformed nucleus 225Ra. Our
calculation includes several effects neglected in earlier work, including self
consistency and polarization of the core by the last nucleon. We confirm that
the Schiff moment is large compared to those of reflection-symmetric nuclei,
though ours is generally a few times smaller than recent estimates.Comment: Typos corrected, references added, minor changesin text. Version to
appear in PRC. 10 pages, 4 figure
Dark matter cores in the Fornax and Sculptor dwarf galaxies: joining halo assembly and detailed star formation histories
We combine the detailed Star Formation Histories of the Fornax and Sculptor
dwarf Spheroidals with the Mass Assembly History of their dark matter (DM) halo
progenitors to estimate if the energy deposited by Supernova type II (SNeII) is
sufficient to create a substantial DM core. Assuming the efficiency of energy
injection of the SNeII into DM particles is , we find
that a single early episode, , that combines the
energy of all SNeII due to explode over 0.5 Gyr, is sufficient to create a core
of several hundred parsecs in both Sculptor and Fornax. Therefore, our results
suggest that it is energetically plausible to form cores in Cold Dark Matter
(CDM) halos via early episodic gas outflows triggered by SNeII. Furthermore,
based on CDM merger rates and phase-space density considerations, we argue that
the probability of a subsequent complete regeneration of the cusp is small for
a substantial fraction of dwarf-size haloes.Comment: ApJL accepted versio
Identification of redundant and synergetic circuits in triplets of electrophysiological data
Neural systems are comprised of interacting units, and relevant information
regarding their function or malfunction can be inferred by analyzing the
statistical dependencies between the activity of each unit. Whilst correlations
and mutual information are commonly used to characterize these dependencies,
our objective here is to extend interactions to triplets of variables to better
detect and characterize dynamic information transfer. Our approach relies on
the measure of interaction information (II). The sign of II provides
information as to the extent to which the interaction of variables in triplets
is redundant (R) or synergetic (S). Here, based on this approach, we calculated
the R and S status for triplets of electrophysiological data recorded from
drug-resistant patients with mesial temporal lobe epilepsy in order to study
the spatial organization and dynamics of R and S close to the epileptogenic
zone (the area responsible for seizure propagation). In terms of spatial
organization, our results show that R matched the epileptogenic zone while S
was distributed more in the surrounding area. In relation to dynamics, R made
the largest contribution to high frequency bands (14-100Hz), whilst S was
expressed more strongly at lower frequencies (1-7Hz). Thus, applying
interaction information to such clinical data reveals new aspects of
epileptogenic structure in terms of the nature (redundancy vs. synergy) and
dynamics (fast vs. slow rhythms) of the interactions. We expect this
methodology, robust and simple, can reveal new aspects beyond pair-interactions
in networks of interacting units in other setups with multi-recording data sets
(and thus, not necessarily in epilepsy, the pathology we have approached here).Comment: 31 pages, 6 figures, 3 supplementary figures. To appear in the
Journal of Neural Engineering in its current for
Vibrations on pulse tube based Dry Dilution Refrigerators for low noise measurements
Dry Dilution Refrigerators (DDR) based on pulse tube cryo-coolers have
started to replace Wet Dilution Refrigerators (WDR) due to the ease and low
cost of operation. However these advantages come at the cost of increased
vibrations, induced by the pulse tube. In this work, we present the vibration
measurements performed on three different commercial DDRs. We describe in
detail the vibration measurement system we assembled, based on commercial
accelerometers, conditioner and DAQ, and examined the effects of the various
damping solutions utilized on three different DDRs, both in the low and high
frequency regions. Finally, we ran low temperature, pseudo-massive (30 and 250
g) germanium bolometers in the best vibration-performing system under study and
report on the results
Diagnostic Palpation in Osteopathic Medicine: A Putative Neurocognitive Model of Expertise
This thesis examines the extent to which the development of expertise in diagnostic palpation in osteopathic medicine is associated with changes in cognitive processing. Chapter 2 and Chapter 3 review, respectively, the literature on the role of analytical and non-analytical processing in osteopathic and medical clinical decision making; and the relevant research on the use of vision and haptics and the development of expertise within the context of an osteopathic clinical examination. The two studies reported in Chapter 4 examined the mental representation of knowledge and the role of analogical reasoning in osteopathic clinical decision making. The results reported there demonstrate that the development of expertise in osteopathic medicine is associated with the processes of knowledge encapsulation and script formation. The four studies reported in Chapters 5 and 6 investigate the way in which expert osteopaths use their visual and haptic systems in the diagnosis of somatic dysfunction. The results suggest that ongoing clinical practice enables osteopaths to combine visual and haptic sensory signals in a more efficient manner. Such visuo-haptic sensory integration is likely to be facilitated by top-down processing associated with visual, tactile, and kinaesthetic mental imagery. Taken together, the results of the six studies reported in this thesis indicate that the development of expertise in diagnostic palpation in osteopathic medicine is associated with changes in cognitive processing. Whereas the experts’ diagnostic judgments are heavily influenced by top-down, non-analytical processing; students rely, primarily, on bottom-up sensory processing from vision and haptics. Ongoing training and clinical practice are likely to lead to changes in the clinician’s neurocognitive architecture. This thesis proposes an original model of expertise in diagnostic palpation which has implications for osteopathic education. Students and clinicians should be encouraged to appraise the reliability of different sensory cues in the context of clinical examination, combine sensory data from different channels, and consider using both analytical and nonanalytical reasoning in their decision making. Importantly, they should develop their skills of criticality and their ability to reflect on, and analyse their practice experiences in and on action
Low-energy neutrinos at off-axis from a standard beta-beam
We discuss a scenario to extract up to 150 MeV neutrinos at a standard
beta-beam facility using one and two detectors off-axis. In particular we show
that the high-energy component of the neutrino fluxes can be subtracted through
a specific combination of the response of two off-axis detectors. A systematic
analysis of the neutrino fluxes using different detector geometries is
presented, as well as a comparison with the expected fluxes at a low-energy
beta-beam facility. The presented option could offer an alternative way to
perform low-energy neutrino experiments.Comment: 9 pages, 6 figure
Control of fluorescence in quantum emitter and metallic nanoshell hybrids for medical applications
We study the light emission from quantum emitter and double metallic
nanoshell hybrid systems. Quantum emitters act as local sources which transmit
their light efficiently due to a double nanoshell near field. The double
nanoshell consists a dielectric core and two outer nanoshells
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