Search results for "nucleus"
showing 10 items of 1803 documents
Bioassays to monitor taspase1 function for the identification of pharmacogenetic inhibitors
2011
Background Threonine Aspartase 1 (Taspase1) mediates cleavage of the mixed lineage leukemia (MLL) protein and leukemia provoking MLL-fusions. In contrast to other proteases, the understanding of Taspase1's (patho)biological relevance and function is limited, since neither small molecule inhibitors nor cell based functional assays for Taspase1 are currently available. Methodology/Findings Efficient cell-based assays to probe Taspase1 function in vivo are presented here. These are composed of glutathione S-transferase, autofluorescent protein variants, Taspase1 cleavage sites and rational combinations of nuclear import and export signals. The biosensors localize predominantly to the cytoplasm…
Ab initio limits of atomic nuclei
2019
We predict the limits of existence of atomic nuclei, the proton and neutron drip lines, from the light through medium-mass regions. Starting from a chiral two- and three-nucleon interaction with good saturation properties, we use the valence-space in-medium similarity renormalization group to calculate ground-state and separation energies from helium to iron, nearly 700 isotopes in total. We use the available experimental data to quantify the theoretical uncertainties for our ab initio calculations towards the drip lines. Where the drip lines are known experimentally, our predictions are consistent within the estimated uncertainty. For the neutron-rich sodium to chromium isotopes, we provid…
Molecular determinants of large cargo transport into the nucleus
2020
Nucleocytoplasmic transport is tightly regulated by the nuclear pore complex (NPC). Among the thousands of molecules that cross the NPC, even very large (>15 nm) cargoes such as pathogens, mRNAs and pre-ribosomes can pass the NPC intact. For these cargoes, there is little quantitative understanding of the requirements for their nuclear import, especially the role of multivalent binding to transport receptors via nuclear localisation sequences (NLSs) and the effect of size on import efficiency. Here, we assayed nuclear import kinetics of 30 large cargo models based on four capsid-like particles in the size range of 17–36 nm, with tuneable numbers of up to 240 NLSs. We show that the requireme…
Recent results from PHENIX on the evolution of hot QCD
2014
The Relativistic Heavy Ion Collider’s (RHIC) energy scan program explores the phase transition between the hadron gas and the quark gluon plasma phases by varying center-of-mass energies from √sNN = 7.7 to 200 GeV and using various system sizes. The nuclear modification factor of π0 and the azimuthal anisotropy of charged hadrons were measured in Au+Au collisions at c.m. energies √sNN = 39, 62.4 and 200 GeV. In addition, we present recent results of direct photon yield and anisotropy measurements in Au+Au collisions at c.m. energy √sNN = 200 GeV.
Characterization of the shape-staggering effect in mercury nuclei
2018
In rare cases, the removal of a single proton (Z) or neutron (N) from an atomic nucleus leads to a dramatic shape change. These instances are crucial for understanding the components of the nuclear interactions that drive deformation. The mercury isotopes (Z = 80) are a striking example1,2: their close neighbours, the lead isotopes (Z = 82), are spherical and steadily shrink with decreasing N. The even-mass (A = N + Z) mercury isotopes follow this trend. The odd-mass mercury isotopes 181,183,185Hg, however, exhibit noticeably larger charge radii. Due to the experimental difficulties of probing extremely neutron-deficient systems, and the computational complexity of modelling such heavy nucl…
Applicability of pion-nucleus Drell-Yan data in global analysis of nuclear parton distribution functions
2017
Despite the success of modern nuclear parton distribution functions (nPDFs) in describing nuclear hard-process data, they still suffer from large uncertainties. One of the poorly constrained features is the possible asymmetry in nuclear modifications of valence $u$ and $d$ quarks. We study the possibility of using pion-nucleus Drell-Yan dilepton data as a new constraint in the global analysis of nPDFs. We find that the nuclear cross-section ratios from the NA3, NA10 and E615 experiments can be used without imposing significant new theoretical uncertainties and, in particular, that these datasets may have some constraining power on the $u$/$d$ -asymmetry in nuclei.
Exclusive heavy vector meson production at next-to-leading order in the dipole picture
2021
We calculate exclusive production of a longitudinally polarized heavy vector meson at next-to-leading order in the dipole picture. The large quark mass allows us to separately include both the first QCD correction proportional to the coupling constant $\alpha_s$, and the first relativistic correction suppressed by the quark velocity $v^2$. Both of these corrections are found to be numerically important in $\mathrm{J}/\psi$ production. The results obtained are directly suitable for phenomenological calculations. We also demonstrate how vector meson production provides complementary information to structure function analyses when one extracts the initial condition for the energy evolution of …
D^- mesic atoms
2011
The anti-D meson self-energy is evaluated self-consistently, using unitarized coupled-channel theory, by computing the in-medium meson-baryon T-matrix in the C=-1,S=0 sector. The heavy pseudo-scalar and heavy vector mesons, anti-D and anti-D^*, are treated on equal footing as required by heavy quark spin symmetry. Results for energy levels and widths of D^- mesic atoms in 12C, 40Ca, 118Sn and 208Pb are presented. The spectrum contains states of atomic and of nuclear types for all nuclei. anti-D^0--nucleus bound states are also obtained. We find that, after electromagnetic and nuclear cascade, these systems end up with the anti-D bound in the nucleus, either as a meson or as part of a exotic…
Mesonic decay of 5ΛHe with quark-model-based hypernuclear wave function
1993
Abstract We have evaluated the mesonic decay of the 5 Λ He hypernucleus by using a Λ wave function generated from the quark cluster model. As a consequence of the Λ N repulsion at short distances we obtain a Λ wave function in the nucleus with a large radius. The smaller overlap with the 4 He core with respect to simpler wave functions and the effect of the pion renormalization increase the mesonic width considerably and one obtains a good reproduction of the experimental data.
The neurobiological bases for the pharmacotherapy of nicotine addiction.
2007
Nicotine, the major psychoactive agent present in tobacco, acts as a potent addictive drug both in humans and laboratory animals, whose locomotor activity is also stimulated. A large body of evidence indicates that the locomotor activation and the reinforcing effects of nicotine may be related to its stimulatory effects on the mesolimbic dopaminergic function. Thus, it is now well established that nicotine can increase in vivo DA outflow in the nucleus accumbens and the corpus striatum. The stimulatory effect of nicotine on DA release most probably results from its ability to excite the neuronal firing rate and to increase the bursting activity of DA neurons in the substantia nigra pars com…