High Resolution Photoemission Study on Low-T_K Ce Systems: Kondo Resonance, Crystal Field Structures, and their Temperature Dependence

We present a high-resolution photoemission study on the strongly correlated Ce-compounds CeCu_6, CeCu_2Si_2, CeRu_2Si_2, CeNi_2Ge_2, and CeSi_2. Using a normalization procedure based on a division by the Fermi-Dirac distribution we get access to the spectral density of states up to an energy of 5 k_BT above the Fermi energy E_F. Thus we can resolve the Kondo resonance and the crystal field (CF) fine-structure for different temperatures above and around the Kondo temperature T_K. The CF peaks are identified with multiple Kondo resonances within the multiorbital Anderson impurity model. Our theoretical 4f spectra, calculated from an extended non-crossing approximation (NCA), describe consistently the observed photoemission features and their temperature dependence. By fitting the NCA spectra to the experimental data and extrapolating the former to low temperatures, T_K can be extracted quantitatively. The resulting values for T_K and the crystal field energies are in excellent agreement with the results from bulk sensitive measurements, e.g. inelastic neutron scattering.Comment: 16 two-column pages, 10 figure

The high-pressure alpha/beta phase transition in lead sulphide (PbS): X-ray powder diffraction and quantum mechanical calculations

The high-pressure behaviour of PbS was investigated by angular dispersive X-ray powder diffraction up to pressures of 6.8 GPa. Experiments were accompanied by first principles calculations at the density functional theory level. By combining both methods reliable data for the elastic properties of rock-salt type alpha- and high-pressure beta-PbS could be obtained. beta-PbS could be determined to crystallise in the CrB-type (B33), with space group Cmcm. The reversible ferro-elastic alpha/beta transition is of first order. It is accompanied by a large volume discontinuity of about 5% and a coexistence region of the two phases. A gliding mechanism of {001} bilayers along one of the cubic -directions governs the phase transition which can be described in terms of group/subgroup relationships via a common subgroup, despite its reconstructive character. The quadrupling of the primitive unit cell indicates a wave vector (0,0,pi/a) on the Delta-line of the Brillouin zone.Comment: 7 pages, 5 figures, 3 tables submitted to EP

Atomic correlations in itinerant ferromagnets: quasi-particle bands of nickel

We measure the band structure of nickel along various high-symmetry lines of the bulk Brillouin zone with angle-resolved photoelectron spectroscopy. The Gutzwiller theory for a nine-band Hubbard model whose tight-binding parameters are obtained from non-magnetic density-functional theory resolves most of the long-standing discrepancies between experiment and theory on nickel. Thereby we support the view of itinerant ferromagnetism as induced by atomic correlations.Comment: 4 page REVTeX 4.0, one figure, one tabl

Aerobic Exercise and Yoga Improve NeuroCognitive Function in Women with Early Psychosis

Impairments of attention and memory are evident in early psychosis, and are associated with functional disability. In a group of stable, medicated women patients, we aimed to determine whether participating in aerobic exercise or yoga improved cognitive impairments and clinical symptoms. A total of 140 female patients were recruited, and 124 received the allocated intervention in a randomized controlled study of 12 weeks of yoga or aerobic exercise compared with a wait-list group. The primary outcomes were cognitive functions including memory and attention. Secondary outcome measures were the severity of psychotic and depressive symptoms, and hippocampal volume. Data from 124 patients were included in the final analysis based on the intention-to-treat principle. Both yoga and aerobic exercise groups demonstrated significant improvements in working memory (P<0.01) with moderate to large effect sizes compared to the wait-list control group. The yoga group showed additional benefits in verbal acquisition (P<0.01) and attention (P=0.01). Both types of exercise improved overall and depressive symptoms (all P≤0.01) after 12 weeks. Small increases in hippocampal volume were observed in the aerobic exercise group compared with wait-list (P=0.01). Both types of exercise improved working memory in early psychosis patients, with yoga having a larger effect on verbal acquisition and attention than aerobic exercise. The application of yoga and aerobic exercise as adjunctive treatments for early psychosis merits serious consideration. This study was supported by the Small Research Funding of the University of Hong Kong (201007176229), and RGC funding (C00240 / 762412) by the Authority of Research, Hong Kong.published_or_final_versio

Temperature dependence of the Kondo resonance and its satellites in CeCu_2Si_2

We present high-resolution photoemission spectroscopy studies on the Kondo resonance of the strongly-correlated Ce system CeCu$_2$Si$_2$. Exploiting the thermal broadening of the Fermi edge we analyze position, spectral weight, and temperature dependence of the low-energy 4f spectral features, whose major weight lies above the Fermi level $E_F$. We also present theoretical predictions based on the single-impurity Anderson model using an extended non-crossing approximation (NCA), including all spin-orbit and crystal field splittings of the 4f states. The excellent agreement between theory and experiment provides strong evidence that the spectral properties of CeCu$_2$Si$_2$ can be described by single-impurity Kondo physics down to $T \approx 5$ K.Comment: 4 pages, 3 figure

The Kondo Resonance in Electron Spectroscopy

The Kondo resonance is the spectral manifestation of the Kondo properties of the impurity Anderson model, and also plays a central role in the dynamical mean-field theory (DMFT) for correlated electron lattice systems. This article presents an overview of electron spectroscopy studies of the resonance for the 4f electrons of cerium compounds, and for the 3d electrons of V_2O_3, including beginning efforts at using angle resolved photoemission to determine the k-dependence of the resonance. The overview includes the comparison and analysis of spectroscopy data with theoretical spectra as calculated for the impurity model and as obtained by DMFT, and the Kondo volume collapse calculation of the cerium alpha-gamma phase transition boundary, with its spectroscopic underpinnings.Comment: 32 pages, 11 figures, 151 references; paper for special issue of J. Phys. Soc. Jpn. on "Kondo Effect--40 Years after the Discovery

Genome-Wide Linkage Scan in Gullah-Speaking African American Families With Type 2 Diabetes: The Sea Islands Genetic African American Registry (Project SuGAR)

OBJECTIVE—The Gullah-speaking African American population from the Sea Islands of South Carolina is characterized by a low degree of European admixture and high rates of type 2 diabetes and diabetic complications. Affected relative pairs with type 2 diabetes were recruited through the Sea Islands Genetic African American Registry (Project SuGAR)

Genome-wide copy number variation study in anorectal malformations

Anorectal malformations (ARMs, congenital obstruction of the anal opening) are among the most common birth defects requiring surgical treatment (2-5/10 000 live-births) and carry significant chronic morbidity. ARMs present either as isolated or as part of the phenotypic spectrum of some chromosomal abnormalities or monogenic syndromes. The etiology is unknown. To assess the genetic contribution to ARMs, we investigated single-nucleotide polymorphisms and copy number variations (CNVs) at genome-wide scale. A total of 363 Han Chinese sporadic ARM patients and 4006 Han Chinese controls were included. Overall, we detected a 1.3-fold significant excess of rare CNVs in patients. Stratification of patients by presence/absence of other congenital anomalies showed that while syndromic ARM patients carried significantly longer rare duplications than controls (P = 0.049), non-syndromic patients were enriched with both rare deletions and duplications when compared with controls (P = 0.00031). Twelve chromosomal aberrations and 114 rare CNVs were observed in patients but not in 868 controls nor 11 943 healthy individuals from the Database of Genomic Variants. Importantly, these aberrations were observed in isolated ARM patients. Gene-based analysis revealed 79 genes interfered by CNVs in patients only. In particular, we identified a de novo DKK4 duplication. DKK4 is a member of the WNT signaling pathway which is involved in the development of the anorectal region. In mice, Wnt disruption results in ARMs. Our data suggest a role for rare CNVs not only in syndromic but also in isolated ARM patients and provide a list of plausible candidate genes for the disorder.postprin

Deep Learning-based Method for Fully Automatic Quantification of Left Ventricle Function from Cine MR Images: A Multivendor, Multicenter Study

Purpose: To develop a deep learning–based method for fully automated quantification of left ventricular (LV) function from short-axis cine MR images and to evaluate its performance in a multivendor and multicenter setting. Materials and Methods: This retrospective study included cine MRI data sets obtained from three major MRI vendors in four medical centers from 2008 to 2016. Three convolutional neural networks (CNNs) with the U-NET architecture were trained on data sets of increasing variability: (a) a single-vendor, single-center, homogeneous cohort of 100 patients (CNN1); (b) a single-vendor, multicenter, heterogeneous cohort of 200 patients (CNN2); and (c) a multivendor, multicenter, heterogeneous cohort of 400 patients (CNN3). All CNNs were tested on an independent multivendor, multicenter data set of 196 patients. CNN performance was evaluated with respect to the manual annotations from three experienced observers in terms of (a) LV detection accuracy, (b) LV segmentation accuracy, and (c) LV functional parameter accuracy. Automatic and manual results were compared with the paired Wilcoxon test, Pearson correlation, and Bland-Altman analysis. Results: CNN3 achieved the highest performance on the independent testing data set. The average perpendicular distance compared with manual analysis was 1.1 mm ± 0.3 for CNN3, compared with 1.5 mm ± 1.0 for CNN1 (P < .05) and 1.3 mm ± 0.6 for CNN2 (P < .05). The LV function parameters derived from CNN3 showed a high correlation (r2 ≥ 0.98) and agreement with those obtained by experts for data sets from different vendors and centers. Conclusion: A deep learning–based method trained on a data set with high variability can achieve fully automated and accurate cine MRI analysis on multivendor, multicenter cine MRI data