First-Principles Theory of the Momentum-Dependent Local Ansatz for Correlated Electron System

The momentum-dependent local-ansatz (MLA) wavefunction describes well correlated electrons in solids in both the weak and strong interaction regimes. In order to apply the theory to the realistic system, we have extended the MLA to the first-principles version using the tight-binding LDA+U Hamiltonian. We demonstrate for the paramagnetic Fe that the first-principles MLA can describe a reasonable correlation energy gain and suppression of charge fluctuations due to electron correlations. Furthermore, we show that the MLA yields a distinct momentum dependence of the momentum distribution, and thus improves the Gutzwiller wavefunction.Comment: 8 Pages, 3 figures; to be published in Physics Procedi

Electronic and Superconductivity Properties of FeSe Superconductor

We have investigated theoretically electronic and superconducting properties of FeSe superconductor. The calculated specific heat effective mass is found m*/mband = 2.15. This result is comparable with angle resolved photoemission spectroscopy data with the other Fe-pnictdes compound. The electron-phonon coupling constant is found l = 0.7 for this superconductor. This result is also comparable with the results of linearized augmented plane wave method.  It is observed that the FeSesystem is more correlated system compared to the Fe element

Tricuspid atresia: Where are we now?

Tricuspid atresia (TA) is a complex congenital heart disease that presents with cyanosis in the neonatal period. It is invariably fatal if left untreated and requires multiple stages of palliation. Early recognition and timely surgical intervention are therefore pivotal in the management of these infants. This literature review considers the pathophysiology, presentation, investigations, and classification of TA. Moreover, it discusses the evidence upon which the latest medical and surgical treatments are based, as well as numerous recent case reports. Further work is needed to elucidate the etiology of TA, clarify the role of pharmacotherapy, and optimize the surgical management that these patients receive.None

The role of the angle of the fibularis longus tendon in foot arch support.

INTRODUCTION: Understanding the contribution of the fibularis longus tendon to the support of the midfoot arches has potential therapeutic applications. This cadaveric study sought to quantify this support across both the transverse arch and medial longitudinal arch and to establish whether a correlation exists between this support and the angle at which the tendon enters the sole. MATERIALS AND METHODS: Markers placed in 11 dissected cadaveric foot specimens defined the arch boundaries. Incremental weights up to 150 N were applied to the fibularis longus tendon to simulate progressive muscle contraction, and associated changes in the transverse and medial longitudinal arch boundaries were recorded. RESULTS: A force of 150 N reduced the transverse arch distance by 4.6 (1.7) mm (mean [SD]) and medial longitudinal arch distance by 6.8 (1.4) mm. The angle of the fibularis longus tendon on the sole correlated well with changes in the transverse arch distance (slope ± s.e. = 0.56 ± 0.13 mm/degree, Pearson r = .83, p = .002) but only weakly with the medial longitudinal arch (0.18 ± 0.18 mm/degree, r = .32, p = .33). CONCLUSIONS: The results of this preliminary study raise the possibility that physical therapies targeting the fibularis longus tendon may be valuable in the management of midfoot arch collapse. The correlation observed with the transverse arch suggests the possibility that surgical modification of the angle of the fibularis longus tendon on the sole may benefit patients with transverse arch collapse

Responses of substantia gelatinosa neurons to putative neurotransmitters in an in vitro preparation of the adult rat spinal cord

Extracellular recordings were performed from neurons of the substantia gelatinosa (SG) in an in vitro preparation obtained from the spinal cord of adult rats. About 40% of neurons were spontaneously active. They could be synaptically influenced by low and high threshold fiber input entering the spinal cord through dorsal and ventral and ventral roots. Repetitive low threshold stimulation led to a transient increase in activity of a number of these neurons, whereas high intensity stimulation predominantly reduced excitability. The majority of non-spontaneously active neurons responded to an increase of stimulus intensity covariantly with an increase in firing rate. The excitatory effect of phoretically administeredl-glutamate as well as synaptically induced and spontaneous activity was reduced or abolished by phoretically administered GABA, glycine or the enkephalin-analogued-Ala2-d-Leu5-enkephalin. The actions of the enkephalin analogue were blocked by phoretically applied naloxone. The findings are consistent with the notion from in vivo investigations of a structurally and functionally heterogeneous population of neurons which display a responsiveness to microtopically applied putative neurotransmitters resembling dorsal horn neurons in deeper layers

Nonlocal Excitations and 1/8 Singularity in Cuprates

Momentum-dependent excitation spectra of the two-dimensional Hubbard model on the square lattice have been investigated at zero temperature on the basis of the full self-consistent projection operator method in order to clarify nonlocal effects of electron correlations on the spectra. It is found that intersite antiferromagnetic correlations cause shadow bands and enhance the Mott-Hubbard splittings near the half-filling. Furthermore nonlocal excitations are shown to move the critical doping concentration $\delta^{\ast}_{h}$, at which the singular quasiparticle peak is located just on the Fermi level, from $\delta^{\ast}_{h}=0.153$ (the single-site value) to $\delta^{\ast}_{h}=0.123$. The latter suggests the occurance of an instability such as the stripe at $\delta^{\ast}_{h}=1/8$.Comment: 4 pages, 5 figures; to be published in the Journal of Korean Physical Society (ICM12