The Coulomb interaction among massless Dirac fermions in graphene is unscreened around the isotropic Dirac points, causing a logarithmic velocity renormalization and a cone reshaping. In less symmetric Dirac materials possessing anisotropic cones with tilted axes, the Coulomb interaction can provide still more exotic phenomena, which have not been experimentally unveiled yet. Here, using site-selective nuclear magnetic resonance, we find a non-uniform cone reshaping accompanied by a bandwidth reduction and an emergent ferrimagnetism in tilted Dirac cones that appear on the verge of charge ordering in an organic compound. Our theoretical analyses based on the renormalization-group approach and the Hubbard model show that these observations are the direct consequences of the long-range and short-range parts of the Coulomb interaction, respectively. The cone reshaping and the bandwidth renormalization, as well as the magnetic behaviour revealed here, can be ubiquitous and vital for many Dirac materials.

Recent advances in the study of nodal Weyl fermions (WFs), quasi-relativistic massless particles, constitute a novel realm of quantum many-body phenomena. The Coulomb interaction in such systems, having a zero density of states at the Fermi level, is of particular interest, since in contrast to conventional correlated metals, its long-ranged component is unscreened. Here, through nuclear-magnetic-resonance (NMR) measurements, we unveil the exotic spin correlations of two-dimensional WFs in an organic material, causing a divergent increase of the Korringa ratio by a factor of 1000 upon cooling, in striking contrast with conventional metallic behaviors. Combined with model calculations, we show that this divergence stems from the interaction-driven velocity renormalization that almost exclusively suppresses the zero-momentum spin fluctuations. At low temperatures, the NMR rate shows a remarkable increase, which is shown by numerical analyses to correspond to inter-node excitonic fluctuations, precursor of a transition from massless to massive quasiparticles.The WFs are massless quasiparticles in matter exhibiting a linear energy-momentum dispersion, with low-energy properties governed by the relativistic Dirac-Weyl theory (1). They have been discovered in a range of materials in two-dimensional (2D) and three-dimensional (3D) systems, where extensive studies focusing upon their relativistic and topological aspects revealed unconventional charge (2) and spin (3-6) responses. In contrast to the massive electron systems subjected to short-range electronic correlations, the Coulomb interaction among WFs has a highly unusual characteristic, since its long-range component is unscreened at the bandcrossing nodes due to the vanishing density of states (2). As a result, anomalous phenomena directly induced by the long-range interactions come along, in which the strength of the interaction is characterized by a dimensionless coupling constant , given by the ratio of the 3 Coulomb potential to the electronic kinetic energy (1, 2). For instance, in a weak coupling regime, recent studies have found an upward renormalization of the electron velocity in the 2D system graphene (1, 2, 7), in marked contrast to its suppression in conventional correlated materials. In strong coupling, theoretical studies have predicted an even more exotic phenomenon: an excitonic mass gap opening, which originates from the incipient instability of massless fermions, as first discussed in high-energy physics (8, 9) and more recently in the context of condensed matter (10-12). In spite of a great deal of theoretical advances, however, the size of  proves to be rather small in a range of materials (1, 2); consequently, experimental characterization of WFs has remained largely limited especially under strong coupling, and the excitonic instability is yet to be investigated.Here, by combining NMR experiments and model calculations, we demonstrate the realization of a strongly-coupled 2D WF system in the organic salt -(BEDT-TTF)2I3 (-I 3 ) a...

We present a simple model for the γN → ππN reaction which reproduces the cross sections of the π + π − p, π + π − n, π + π 0 n and π − π 0 p channels over the range of the energies 0.41−0.85 GeV. We use the dynamical model for the resonances, ∆(1232), N * (1520) and ρ-meson. The total photoabsorption off a nucleon is also discussed.PACS number(s): 25.20.Dc, 25.20.Lj

Recent developments in imaging technology have enabled CT and MR cholangiopancreatography (MRCP) to provide minimally invasive alternatives to endoscopic retrograde cholangiopancreatography for the pre- and post-operative assessment of biliary disease. This article describes anatomical variants of the biliary tree with surgical significance, followed by comparison of CT and MR cholangiographies. Drip infusion cholangiography with CT (DIC-CT) enables high-resolution three-dimensional anatomical representation of very small bile ducts (e.g. aberrant branches, the caudate branch and the cystic duct), which are potential causes of surgical complications. The disadvantages of DIC-CT include the possibility of adverse reactions to biliary contrast media and insufficient depiction of bile ducts caused by liver dysfunction or obstructive jaundice. Conventional MRCP is a standard, non-invasive method for evaluating the biliary tree. MRCP provides useful information, especially regarding the extrahepatic bile ducts and dilated intrahepatic bile ducts. Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced MRCP may facilitate the evaluation of biliary structure and excretory function. Understanding the characteristics of each type of cholangiography is important to ensure sufficient perioperative evaluation of the biliary system.

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Effects of non-resonant photoproductions arising from two different πN N couplings are investigated in the γN → ππN reaction. We find that the pseudoscalar (PS) πN N coupling is generally preferable to the pseudovector (PV) πN N coupling and particularly the total cross sections are successfully described by the model with the PS πN N coupling. In order to see the difference between the two couplings, we also show the results of invariant mass spectra and helicity-dependent cross sections in various isospin channels calculated with the PS and PV couplings.

The circadian clock, regulating hormonal secretion and metabolisms

The circadian clock is responsible for the generation of circadian rhythms in hormonal secretion and metabolism. These peripheral clocks could be reset by various cues in order to adapt to environmental variations. The ovary can be characterized as having highly dynamic physiology regulated by gonadotropins. Here, we aimed to address the status of circadian clock in the ovary, and to explore how gonadotropins could regulate clockwork in granulosa cells (GCs). To this end, we mainly utilized the immunohistochemistry, RT-PCR, and real-time monitoring of gene expression methods. PER1 protein was constantly abundant across the daily cycle in the GCs of immature ovaries. In contrast, PER1 protein level was obviously cyclic through the circadian cycle in the luteal cells of pubertal ovaries. In addition, both FSH and LH induced Per1 expression in cultured immature and mature GCs, respectively. The promoter analysis revealed that the Per1 expression was mediated by the cAMP response element binding protein. In cultured transgenic GCs, both FSH and LH also induced the circadian oscillation of Per2. However, the Per2 oscillation promoted by FSH quickly dampened within only one cycle, whereas the Per2 oscillation promoted by LH was persistently maintained. Collectively, these findings strongly suggest that both FSH and LH play an important role in regulating circadian clock in the ovary; however, they might exert differential actions on the clockwork in vivo due to each specific role within ovarian physiology.