201 research outputs found
Framing the ultimatum game: the contribution of simulation
It has now become widely accepted that economic decisions are influenced by cognitive and emotional processes. In the present study, we aimed at disentangling the neural mechanisms associated with the way in which the information is formulated, i.e., framing effect, in terms of gain or loss, which influences people\u2019s decisions. Participants played a fMRI version of the Ultimatum Game (UG) where we manipulated bids through two different frames: the expression \u201cI give you\u201d (gain) focusing on money the respondent would receive if she/he agreed with the proponent, and the expression \u201cI take\u201d (loss) focusing on the money that would be removed from the respondent in the event that she/he accepted the offer. Neuroimaging data revealed a frame by response interaction, showing an increase of neural activity in the right rolandic operculum/insular cortex, the anterior cingulate, among other regions, for accepting the frame \u201cI take\u201d vs. rejecting, as compared to accepting the frame \u201cI give you\u201d vs. rejecting. In addition, the left occipito-temporal junction was activated for \u201cI take\u201d vs. \u201cI give you\u201d for offer 5, corresponding to the equal offer made unpleasant by the presence of the frame \u201cI take,\u201d where is the proposer that takes the money. Our data extend the current understanding of the neural substrates of social decision making, by disentangling the structures sensitive to the way in which the information is formulated (i.e., framing effect), in terms of gain or loss
Atomic fountains and optical clocks at SYRTE: status and perspectives
In this article, we report on the work done with the LNE-SYRTE atomic clock
ensemble during the last 10 years. We cover progress made in atomic fountains
and in their application to timekeeping. We also cover the development of
optical lattice clocks based on strontium and on mercury. We report on tests of
fundamental physical laws made with these highly accurate atomic clocks. We
also report on work relevant to a future possible redefinition of the SI
second
Landau and dynamical instabilities of Bose-Einstein condensates with superfluid flow in a Kronig-Penney potential
We study the elementary excitations of Bose-Einstein condensates in a
one-dimensional periodic potential and discuss the stability of superfluid flow
based on the Kronig-Penney model. We analytically solve the Bogoliubov
equations and calculate the excitation spectrum. The Landau and dynamical
instabilities occur in the first condensate band when the superfluid velocity
exceeds certain critical values, which agrees with the result of condensates in
a sinusoidal potential. It is found that the onset of the Landau instability
coincides with the point where the perfect transmission of low-energy
excitations is forbidden, while the dynamical instability occurs when the
effective mass is negative. It is well known that the condensate band has a
peculiar structure called swallowtail when the periodic potential is shallow
compared to the mean field energy. We find that the upper side of the
swallowtail is dynamically unstable although the excitations have the linear
dispersion reflecting the positive effective mass.Comment: 6 pages, 2 figures, Proceedings of the International Symposium on
Quantum Fluids and Solids (QFS2006
Shortcut to adiabaticity in spinor condensates
We devise a method to shortcut the adiabatic evolution of a spin-1 Bose gas with an external magnetic field as the control parameter. An initial many-body state with almost all bosons populating the Zeeman sublevel m = 0 is evolved to a final state very close to a macroscopic spin-singlet condensate, a fragmented state with three macroscopically occupied Zeeman states. The shortcut protocol, obtained by an approximate mapping to a harmonic oscillator Hamiltonian, is compared to linear and exponential variations of the control parameter. We find a dramatic speedup of the dynamics when using the shortcut protocol
Coarse-Grained Finite-Temperature Theory for the Condensate in Optical Lattices
In this work, we derive a coarse-grained finite-temperature theory for a Bose
condensate in a one-dimensional optical lattice, in addition to a confining
harmonic trap potential. We start from a two-particle irreducible (2PI)
effective action on the Schwinger-Keldysh closed-time contour path. In
principle, this action involves all information of equilibrium and
non-equilibrium properties of the condensate and noncondensate atoms. By
assuming an ansatz for the variational function, i.e., the condensate order
parameter in an effective action, we derive a coarse-grained effective action,
which describes the dynamics on the length scale much longer than a lattice
constant. Using the variational principle, coarse-grained equations of motion
for the condensate variables are obtained. These equations include a
dissipative term due to collisions between condensate and noncondensate atoms,
as well as noncondensate mean-field. To illustrate the usefulness of our
formalism, we discuss a Landau instability of the condensate in optical
lattices by using the coarse-grained generalized Gross-Pitaevskii
hydrodynamics. We found that the collisional damping rate due to collisions
between the condensate and noncondensate atoms changes sign when the condensate
velocity exceeds a renormalized sound velocity, leading to a Landau instability
consistent with the Landau criterion. Our results in this work give an insight
into the microscopic origin of the Landau instability.Comment: 38 pages, 2 figures. Submitted to Journal of Low Temperature Physic
Toward optimization of postremission therapy for residual disease-positive patients with acute myeloid leukemia
Purpose:Despite the identification of several baseline prognostic indicators, the outcome of patients with acute myeloid leukemia (AML) is generally heterogeneous. The effects of autologous (AuSCT) or allogeneic stem-cell transplantation (SCT) are still under evaluation. Minimal residual disease (MRD) states may be essential for assigning patients to therapy-dependent risk categories. Patients and Methods: By multiparametric flow cytometry, we assessed the levels of MRD in 142 patients with AML who achieved complete remission after intensive chemotherapy. Results: A level of 3.5 x 10(-4) residual leukemia cells (RLCs) after consolidation therapy was established to identify MRD-negative and MRD-positive cases, with 5-year relapse-free survival (RFS) rates of 60% and 16%, respectively (P <.0001) and overall survival (OS) rates of 62% and 23%, respectively (P=.0001). Of patients (n = 77) who underwent a transplantation procedure (56 AuSCT and 21 SCT procedures); 42 patients (55%) were MRD positive (28 patients who underwent AuSCT and 14 patients who underwent SCT) and 35 patients (45%) were MRD negative (28 patients who underwent AuSCT and seven who underwent SCT). MRD-negative patients had a favorable prognosis, with only eight (22%) of 35 patients experiencing relapse, whereas 29 (69%) of 42 MRD-positive patients experienced relapse (P <.0001). In this high-risk group of 42 patients, we observed that 23 (82%) of 28 of those who underwent AuSCT experienced relapse, whereas six (43%) of 14 who underwent SCT experienced relapse (P=.014). Patients who underwent SCT also had a higher likelihood of RFS (47% v 14%). Conclusion A threshold of 3.5 x 10(-4) RLCs postconsolidation is critical for predicting disease outcome. MRD-negative patients have a good outcome regardless of the type of transplant they receive. In the MRD-positive group, AuSCT does not improve prognosis and SCT represents the primary option
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