693 research outputs found
Reactivation of single-episode pain patterns in the hippocampus and decision making
Aversive and rewarding experiences can exert a strong influence on subsequent behavior. While decisions are often supported by the value of single past episodes, most research has focused on the role of well-learned value associations. Recent studies have begun to investigate the influence of reward-associated episodes, but it is unclear if these results generalize to negative experiences such as pain. To investigate whether and how the value of previous aversive experiences modulates behavior and brain activity, in our experiments female and male human participants experienced episodes of high or low pain in conjunction with incidental, trial-unique neutral pictures. In an incentive-compatible surprise test phase, we found that participants avoided pain-paired objects. In a separate fMRI experiment, at test, participants exhibited significant pain value memory. Neurally, when participants were re-exposed to pain-paired objects, we found no evidence for reactivation of pain-related patterns in pain-responsive regions such as the anterior insula. Critically, however, we found significant reactivation of pain-related patterns of activity in the hippocampus, such that activity significantly discriminated high versus low pain episodes. Further, stronger reactivation in the anterior hippocampus was related to improved pain value memory performance. Our results demonstrate that single incidental aversive experiences can build memories that affect decision making and that this influence may be supported by the hippocampus
Deterministic quantum mechanics: The role of the Maxwell–Boltzmann distribution
To be accepted by the community, the claim that nuclear motion has to be treated classically must be tested for all kinds of phenomena. For the moment we claim that in a quantum chemical calculation, a classical description of nuclear motion is superior to the use of the Schrödinger equation, and investigate how far we get with this statement. In the present paper we address the question what nuclear quantum statistics means in this context. We will show that the Maxwell–Boltzmann velocity distribution evolves quickly in any molecular dynamics simulation and this guarantees the physically correct behavior of molecular systems. Using first-principles molecular dynamics simulations, or more precisely Car–Parrinello molecular dynamics, we investigate what this means for Bose-Einstein condensates and for Cooper pairs. It turns out that our approach can explain all relevant phenomena. As a consequence, we can introduce a deterministic formulation of quantum mechanics and can get rid of all the paradoxa in traditional quantum mechanics. The basic idea is to treat electrons and nuclei differently
Learning of distant state predictions by the orbitofrontal cortex in humans
Representations of our future environment are essential for planning and decision making. Previous research in humans has demonstrated that the hippocampus is a critical region for forming and retrieving associations, while the medial orbitofrontal cortex (OFC) is an important region for representing information about recent states. However, it is not clear how the brain acquires predictive representations during goal-directed learning. Here, we show using fMRI that while participants learned to find rewards in multiple different Y-maze environments, hippocampal activity was highest during initial exposure and then decayed across the remaining repetitions of each maze, consistent with a role in rapid encoding. Importantly, multivariate patterns in the OFC-VPFC came to represent predictive information about upcoming states approximately 30 s in the future. Our findings provide a mechanism by which the brain can build models of the world that span long-timescales to make predictions
Bistability of Slow and Fast Traveling Waves in Fluid Mixtures
The appearence of a new type of fast nonlinear traveling wave states in
binary fluid convection with increasing Soret effect is elucidated and the
parameter range of their bistability with the common slower ones is evaluated
numerically. The bifurcation behavior and the significantly different
spatiotemporal properties of the different wave states - e.g. frequency, flow
structure, and concentration distribution - are determined and related to each
other and to a convenient measure of their nonlinearity. This allows to derive
a limit for the applicability of small amplitude expansions. Additionally an
universal scaling behavior of frequencies and mixing properties is found.
PACS: 47.20.-k, 47.10.+g, 47.20.KyComment: 4 pages including 5 Postscript figure
Crystallization of the Photosystem II core complex and its chlorophyll binding subunit CP43 from transplastomic plants of Nicotianatabacum
Photosystem II from transplastomic plants of Nicotiana tabacum with a hexahistidine tag at the N-terminal end of the PsbE subunit (α-chain of the cytochrome b559) was purified according to the protocol of Fey et al. (BBA 12:1501–1509, 2008). The protein sample was then subjected to two additional gel filtration runs in order to increase its homogeneity and to standardize the amount of detergent. Large three dimensional crystals of the core complex were obtained. Crystals of one of its chlorophyll binding subunits (CP43) in isolation grew in very similar conditions that differed only in the concentration of the detergent. Diffraction of Photosystem II and CP43 crystals at various synchrotron beamlines was limited to a resolution of 7 and 14 Å, respectively. In both cases the diffraction quality was insufficient for an unambiguous assignment of the crystallographic lattice or space group
LUCI onboard Lagrange, the Next Generation of EUV Space Weather Monitoring
LUCI (Lagrange eUv Coronal Imager) is a solar imager in the Extreme
UltraViolet (EUV) that is being developed as part of the Lagrange mission, a
mission designed to be positioned at the L5 Lagrangian point to monitor space
weather from its source on the Sun, through the heliosphere, to the Earth. LUCI
will use an off-axis two mirror design equipped with an EUV enhanced active
pixel sensor. This type of detector has advantages that promise to be very
beneficial for monitoring the source of space weather in the EUV. LUCI will
also have a novel off-axis wide field-of-view, designed to observe the solar
disk, the lower corona, and the extended solar atmosphere close to the
Sun-Earth line. LUCI will provide solar coronal images at a 2-3 minute cadence
in a pass-band centred on 19.5 nm. Observations made through this pass-band
allow for the detection and monitoring of semi-static coronal structures such
as coronal holes, prominences, and active regions; as well as transient
phenomena such as solar flares, limb Coronal Mass Ejections (CMEs), EUV waves,
and coronal dimmings. The LUCI data will complement EUV solar observations
provided by instruments located along the Sun-Earth line such as PROBA2-SWAP,
SUVI-GOES and SDO-AIA, as well as provide unique observations to improve space
weather forecasts. Together with a suite of other remote-sensing and in-situ
instruments onboard Lagrange, LUCI will provide science quality operational
observations for space weather monitoring
Influence of through-flow on linear pattern formation properties in binary mixture convection
We investigate how a horizontal plane Poiseuille shear flow changes linear
convection properties in binary fluid layers heated from below. The full linear
field equations are solved with a shooting method for realistic top and bottom
boundary conditions. Through-flow induced changes of the bifurcation thresholds
(stability boundaries) for different types of convective solutions are deter-
mined in the control parameter space spanned by Rayleigh number, Soret coupling
(positive as well as negative), and through-flow Reynolds number. We elucidate
the through-flow induced lifting of the Hopf symmetry degeneracy of left and
right traveling waves in mixtures with negative Soret coupling. Finally we
determine with a saddle point analysis of the complex dispersion relation of
the field equations over the complex wave number plane the borders between
absolute and convective instabilities for different types of perturbations in
comparison with the appropriate Ginzburg-Landau amplitude equation
approximation. PACS:47.20.-k,47.20.Bp, 47.15.-x,47.54.+rComment: 19 pages, 15 Postscript figure
Combined inhibition of Aurora-A and ATR kinase results in regression of MYCN-amplified neuroblastoma
Amplification of MYCN is the driving oncogene in a subset of high-risk neuroblastoma. The MYCN protein and the Aurora-A kinase form a complex during S phase that stabilizes MYCN. Here we show that MYCN activates Aurora-A on chromatin, which phosphorylates histone H3 at serine 10 in S phase, promotes the deposition of histone H3.3 and suppresses R-loop formation. Inhibition of Aurora-A induces transcription-replication conflicts and activates the Ataxia telangiectasia and Rad3 related (ATR) kinase, which limits double-strand break accumulation upon Aurora-A inhibition. Combined inhibition of Aurora-A and ATR induces rampant tumor-specific apoptosis and tumor regression in mouse models of neuroblastoma, leading to permanent eradication in a subset of mice. The therapeutic efficacy is due to both tumor cell-intrinsic and immune cell-mediated mechanisms. We propose that targeting the ability of Aurora-A to resolve transcription-replication conflicts is an effective therapy for MYCN-driven neuroblastoma (141 words)
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