The fact that feed-forward and top-down propagation of sensory information use distinct frequency bands is an appealing assumption for which evidence remains scarce. Here we obtain human depth ...recordings from two auditory cortical regions in both hemispheres, while subjects listen to sentences, and show that information travels in each direction using separate frequency channels. Bottom-up and top-down propagation dominates in γ- and δ-β (<40 Hz) bands, respectively. The predominance of low frequencies for top-down information transfer is confirmed by cross-regional frequency coupling, which indicates that the power of γ-activity in A1 is modulated by the phase of δ-β activity sampled from association auditory cortex (AAC). This cross-regional coupling effect is absent in the opposite direction. Finally, we show that information transfer does not proceed continuously but by time windows where bottom-up or top-down processing alternatively dominates. These findings suggest that the brain uses both frequency- and time-division multiplexing to optimize directional information transfer.
The primary efficacy outcome in trials of urate lowering therapy (ULT) for gout is serum urate (SU). The aim of this study was to examine the strength of the relationship between SU and ...patient-important outcomes to determine whether SU is an adequate surrogate endpoint for clinical trials.
Multiple databases through October 2017 were searched. Randomized controlled trials comparing any ULT in people with gout with any control or placebo, ≥three months duration were included. Open label extension (OLE) trial data were included in secondary analyses. Standardized data elements were extracted independently by two reviewers.
Ten RCTs and 3 OLE studies were identified. From the RCTs (maximum duration 24 months) meta-regression did not reveal an association between the relative risk of a gout flare and the difference in proportions of individuals with SU < 6mg/dL (P = 0.47; R2 = 8%). In a post hoc analysis, the ratio of the time in months at which the proportion of individuals having a flare was reported/time in months at which the proportion of individuals with SU < 6mg/dL was reported was calculated and studies where the ratio was <2 were excluded. Using the remaining 6 studies there was an association between proportion of individuals achieving SU < 6mg/dL and gout flares (over patient years). Duration of ULT was inversely associated with the proportion of patients experiencing a flare. Study duration and variability in reporting of outcomes limited the analysis. Observational studies supported the trend of fewer flares in those with lower SU.
Based on aggregate clinical trial-level data an association between SU and gout flare could not be confirmed. However, based on observational ecological study design data—including longer duration extension studies—SU < 6mg/dL was associated with reduced gout flares.
It is widely accepted that transport is stressful for horses, but only a few studies are available involving horses that are transported regularly and are accustomed to transport. We determined ...salivary cortisol immunoreactivity (IR), fecal cortisol metabolites, beat-to-beat (RR) interval, and heart rate variability (HRV) in transport-experienced horses (N
=
7) in response to a 2-d outbound road transport over 1370
km and 2-d return transport 8 d later. Salivary cortisol IR was low until 60
min before transport but had increased (
P
<
0.05) 30
min before loading. Transport caused a further marked increase (
P
<
0.001), but the response tended to decrease with each day of transport. Concentrations of fecal cortisol metabolites increased on the second day of both outbound and return transports and reached a maximum the following day (
P
<
0.001). During the first 90
min on Day 1 of outbound transport, mean RR interval decreased (
P
<
0.001). Standard deviations of RR interval (SDRR) decreased transiently (
P
<
0.01). The root mean square of successive RR differences (RMSSD) decreased at the beginning of the outbound and return transports (
P
<
0.01), reflecting reduced parasympathetic tone. On the first day of both outbound and return transports, a transient rise in geometric HRV variable standard deviation 2 (SD2) occurred (
P
<
0.01), indicating increased sympathetic activity. In conclusion, transport of experienced horses leads to increased cortisol release and changes in heart rate and HRV, which is indicative of stress. The degree of these changes tended to be most pronounced on the first day of both outbound and return transport.
Abstract
We review recent progress and motivate the need for further developments in nuclear optical potentials that are widely used in the theoretical analysis of nucleon elastic scattering and ...reaction cross sections. In regions of the nuclear chart away from stability, which represent a frontier in nuclear science over the coming decade and which will be probed at new rare-isotope beam facilities worldwide, there is a targeted need to quantify and reduce theoretical reaction model uncertainties, especially with respect to nuclear optical potentials. We first describe the primary physics motivations for an improved description of nuclear reactions involving short-lived isotopes, focusing on its benefits for fundamental science discoveries and applications to medicine, energy, and security. We then outline the various methods in use today to build optical potentials starting from phenomenological, microscopic, and
ab initio
methods, highlighting in particular, the strengths and weaknesses of each approach. We then discuss publicly-available tools and resources facilitating the propagation of recent progresses in the field to practitioners. Finally, we provide a set of open challenges and recommendations for the field to advance the fundamental science goals of nuclear reaction studies in the rare-isotope beam era. This paper is the outcome of the Facility for Rare Isotope Beams Theory Alliance (FRIB-TA) topical program ‘Optical Potentials in Nuclear Physics’ held in March 2022 at FRIB. Its content is non-exhaustive, was chosen by the participants and reflects their efforts related to optical potentials.
Accurate multiplicities of prompt fission neutrons emitted in neutron-induced fission on a large energy range are essential for fundamental and applied nuclear physics. Measuring them to high ...precision for radioactive fissioning nuclides remains, however, an experimental challenge. In this work, the average prompt-neutron multiplicity emitted in the 239Pu(n,f) reaction was extracted as a function of the incident-neutron energy, over the range 1-700 MeV, with a novel technique, which allowed to minimize and correct for the main sources of bias and thus achieve unprecedented precision.
At low energies, our data validate for the first time the ENDF/B-VIII.0 nuclear data evaluation with an independent measurement and reduce the evaluated uncertainty by up to 60%. This work opens up the possibility of precisely measuring prompt fission neutron multiplicities on highly radioactive nuclei relevant for an essential component of energy production world-wide.
Here, the energy spectrum of prompt neutron emitted in fission (PFNS) plays a very important role in nuclear science and technology. A Coordinated Research Project (CRP) "Evaluation of Prompt Fission ...Neutron Spectra of Actinides" was established by the IAEA Nuclear Data Section in 2009, with the major goal to produce new PFNS evaluations with uncertainties for actinide nuclei.
Measuring prompt fission neutrons to high precision is an experimental challenge, especially for radioactive fissioning nuclides. However, accurate average multiplicities, ν¯p, and kinetic energy ...distributions of prompt fission neutrons are essential for fundamental and applied nuclear physics. We present here a recent measurement of the 239Pu (n,f) ν¯p as a function of the incident-neutron energy, over the range 1-700 MeV. The measurement was performed with a cutting-edge setup and an innovative technique, which allowed to minimize and account for the main sources of bias. An unprecedented precision was therefore achieved. Our data are compared to GEF predictions as well as to evaluated libraries. For the first time, at low energies, the ENDF/B-VIII.0 nuclear data evaluation is validated with an independent measurement and the evaluated uncertainty reduced by up to 60%. This work paves the way to precisely measure prompt fission neutron multiplicities on highly radioactive nuclei.
Diving into Raynal’s DWBA code Blanchon, G.; Dupuis, M.; Arellano, H. F. ...
The European physical journal. A, Hadrons and nuclei,
2021/1, Letnik:
57, Številka:
1
Journal Article
Recenzirano
The study of nucleon-nucleus elastic scattering for spherical targets amounts to solving Schrödinger equation with a given optical potential. This potential can be obtained microscopically by taking ...as a starting point the interaction between two nucleons. It can also be obtained in a phenomenological way by postulating the geometry of potential and fitting parameters to reproduce experimental data. Microscopic approaches show in general terms that optical potentials are nonlocal, energy-dependent, complex and dispersive. The nonlocality of the potential leads to an integro-differential equation for the wavefunction. We present here a new version of SIDES (Schrödinger Integro-Differential Equation Solver), a code developed with the participation of Jacques Raynal, extended for nonlocal potentials with first-derivative terms.
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