1,416 research outputs found
Optimal boundary control of a viscous Cahn-Hilliard system with dynamic boundary condition and double obstacle potentials
In this paper, we investigate optimal boundary control problems for
Cahn-Hilliard variational inequalities with a dynamic boundary condition
involving double obstacle potentials and the Laplace-Beltrami operator. The
cost functional is of standard tracking type, and box constraints for the
controls are prescribed. We prove existence of optimal controls and derive
first-order necessary conditions of optimality. The general strategy, which
follows the lines of the recent approach by Colli, Farshbaf-Shaker, Sprekels
(see the preprint arXiv:1308.5617) to the (simpler) Allen-Cahn case, is the
following: we use the results that were recently established by Colli, Gilardi,
Sprekels in the preprint arXiv:1407.3916 [math.AP] for the case of
(differentiable) logarithmic potentials and perform a so-called "deep quench
limit". Using compactness and monotonicity arguments, it is shown that this
strategy leads to the desired first-order necessary optimality conditions for
the case of (non-differentiable) double obstacle potentials.Comment: Key words: optimal control; parabolic obstacle problems; MPECs;
dynamic boundary conditions; optimality conditions. arXiv admin note:
substantial text overlap with arXiv:1308.561
Unusual interplay between copper-spin and vortex dynamics in slightly overdoped La{1.83}Sr{0.17}CuO{4}
Our inelastic neutron scattering experiments of the spin excitations in the
slightly overdoped La{1.83}Sr{0.17}CuO{4} compound show that, under the
application of a magnetic field of 5 Tesla, the low-temperature susceptibility
undergoes a weight redistribution centered at the spin-gap energy. Furthermore,
by comparing the temperature dependence of the neutron data with
ac-susceptibility and magnetization measurements, we conclude that the filling
in of the spin gap tracks the irreversibility/melting temperature rather than
Tc2, which indicates an unusual interplay between the magnetic vortices and the
spin excitations even in the slightly overdoped regime of high-temperature
superconductors.Comment: 7 pages, including 5 figure
Interview with Sam Gilardi
Lisa M. Groesz recounts her interview with Sam Gilardihttps://digital.kenyon.edu/elfs_interviews/1050/thumbnail.jp
Interview with Sam Gilardi
Sam Gilardi talks about Lannings\u27 beef production.https://digital.kenyon.edu/elfs_interviews/1046/thumbnail.jp
Doping dependence of the vortex glass and sublimation transitions in the high- superconductor LaSrCuO as determined from macroscopic measurements
Magnetization and ac-susceptibility measurements are used to characterize the
mixed phase of the high-temperature cuprate superconductor
LaSrCuO over a large range of doping (0.075
0.20). The first order vortex lattice phase transition line , the
upper critical field and the second peak have been
investigated up to high magnetic fields (8 Tesla applied perpendicular to the
planes). Our results reveal a strong doping dependence of the magnetic
phase diagram, which can mainly be explained by the increasing anisotropy with
underdoping. Within our interpretation, the first order vortex lattice phase
transition is due to the sublimation (rather than melting) of the vortex
lattice into a gas of pancake vortices, whereas the second peak is related to
the transition to a more disordered vortex glass state.Comment: 7 pages, 5 figure
Influence of higher d-wave gap harmonics on the dynamical magnetic susceptibility of high-temperature superconductors
Using a fermiology approach to the computation of the magnetic susceptibility
measured by neutron scattering in hole-doped high-Tc superconductors, we
estimate the effects on the incommensurate peaks caused by higher d-wave
harmonics of the superconducting order parameter induced by underdoping. The
input parameters for the Fermi surface and d-wave gap are taken directly from
angle resolved photoemission (ARPES) experiments on Bi{2}Sr{2}CaCu{2}O{8+x}
(Bi2212). We find that higher d-wave harmonics lower the momentum dependent
spin gap at the incommensurate peaks as measured by the lowest spectral edge of
the imaginary part in the frequency dependence of the magnetic susceptibility
of Bi2212. This effect is robust whenever the fermiology approach captures the
physics of high-Tc superconductors. At energies above the resonance we observe
diagonal incommensurate peaks. We show that the crossover from parallel
incommensuration below the resonance energy to diagonal incommensuration above
it is connected to the values and the degeneracies of the minima of the
2-particle energy continuum.Comment: 13 pages, 7 figure
Will Widespread Synthetic Opioid Consumption Induce Epigenetic Consequences in Future Generations?
A growing number of evidence demonstrates that ancestral exposure to xenobiotics (pollutants, drugs of abuse, etc.) can perturb the physiology and behavior of descendants. Both maternal and paternal transmission of phenotype across generations has been proved, demonstrating that parental drug history may have significant implications for subsequent generations. In the last years, the burden of novel synthetic opioid (NSO) consumption, due to increased medical prescription of pain medications and to easier accessibility of these substances on illegal market, is raising new questions first in term of public health, but also about the consequences of the parental use of these drugs on future generations. Besides being associated to the neonatal abstinence syndrome, <i>in utero</i> exposure to opioids has an impact on neuronal development with long-term repercussions that are potentially transmitted to subsequent generations. In addition, recent reports suggest that opioid use even before conception influences the reactivity to opioids of the progeny and the following generations, likely through epigenetic mechanisms. This review describes the current knowledge about the transgenerational effects of opioid consumption. We summarize the preclinical and clinical findings showing the implications for the subsequent generations of parental exposure to opioids earlier in life. Limitations of the existing data on NSOs and new perspectives of the research are also discussed, as well as clinical and forensic consequences
LHCb Conditions Database
The LHCb Conditions Database (CondDB) project aims to provide the necessary tools to handle non-event time-varying data. The LCG project COOL provides a generic API to handle this type of data and an interface to it has been integrated into the LHCb framework Gaudi. The interface is based on the Persistency Service infrastructure of Gaudi, allowing the user to load it at run-time only if needed. Since condition data are varying with time, as the events are processed, condition objects in memory must be kept synchronized to the values in the database for the current event time. A specialized service has been developed independently of the COOL API interface to provide an automated and optimized update of the condition objects in memory. The High Level Trigger of LHCb is a specialized version of an LHCb reconstruction/analysis program and as such it will need conditions, like alignments and calibrations, from the conditions database. For performance reasons, the HLT processes running on the Event Filter Farm cannot access the database directly. A special Online implementation of the CondDB service is thus needed under supervision of the LHCb Control system
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