Kondo effect near the Van Hove singularity in biased bilayer graphene

Magnetic impurity adsorbed on one of the carbon planes of a bilayer graphene is studied. The formation of the many-body SU(2) and SU(4) resonances close to the bandgap is analyzed within the mean field Kotliar-Ruckenstein slave boson approach. Impact of enhanced hybridization and magnetic instability of bilayer doped near the Van Hove singularity on the screening of magnetic moment is discussed.Comment: 10 pages, 8 figure

Electric field control of spins in bilayer graphene: Local moment formation and local moment interactions

We study local moment formation for adatoms on bilayer graphene (BLG) within a mean-field theory of the Anderson impurity model. The wavefunctions of the BLG electrons induce strong particle-hole asymmetry and band dependence of the hybridization, which is shown to result in unusual features in the impurity model phase diagram. We also study the effect of varying the chemical potential, as well as varying an electric field perpendicular to the bilayer; the latter modifies the density of states of electrons in BLG and, more significantly, shifts the impurity energy. We show that this leads to regimes in the impurity phase diagram where local moments can be turned on or off by applying modest external electric fields. Finally, we show that the RKKY interaction between local moments can be varied by tuning the chemical potential (as has also been suggested in monolayer graphene) or, more interestingly, by tuning the electric field so that it induces changes in the band structure of BLG.Comment: Revised discussion and figures, 17 page

Gauging the mass of metals in the gas phase of galaxies from the Local Universe to the Epoch of Reionization

The chemical enrichment of dust and metals are vital processes in constraining the star formation history of the universe. Previously, the dust masses of high-redshift star-forming galaxies have been determined through their far-infrared continuum, however, equivalent, and potentially simpler, approaches to determining the metal masses have yet to be explored at $z\gtrsim 2$. Here, we present a new method of inferring the metal mass in the interstellar medium (ISM) of galaxies out to $z\approx 8$, using the far-infrared [CII]$-158\mu$m emission line as a proxy. We calibrated the [CII]-to-$M_{\rm Z,ISM}$ conversion factor based on a benchmark observational sample at $z\approx 0$, in addition to gamma-ray burst sightlines at $z>2$ and cosmological hydrodynamical simulations of galaxies at $z\approx 0$ and $z\approx 6$. We found a universal scaling across redshifts of $\log (M_{\rm Z,ISM}/M_\odot) = \log (L_{\rm [CII]}/L_\odot) - 0.45,$ with a 0.4 dex scatter, which is constant over more than two orders of magnitude in metallicity. We applied this scaling to recent surveys for [CII] in galaxies at $z\gtrsim 2$ and determined the fraction of metals retained in the gas-phase ISM, $M_{\rm Z,ISM} / M_\star$, as a function of redshift showing that an increasing fraction of metals reside in the ISM of galaxies at higher redshifts. We place further constraints on the cosmic metal mass density in the ISM ($\Omega_{\rm Z,ISM}$) at $z\approx 5$ and $\approx 7$, yielding $\Omega_{\rm Z,ISM} = 6.6^{+13}_{-4.3}\times 10^{-7}\,M_\odot\, {\rm Mpc}^{-3}$ ($z\approx 5$) and $\Omega_{\rm Z,ISM} = 2.0^{+3.5}_{-1.3}\times 10^{-7}\,M_\odot\, {\rm Mpc}^{-3}$ ($z\approx 7$). These results are consistent with the expected metal yields from the integrated star formation history at the respective redshifts. This suggests that the majority of metals produced at $z\gtrsim 5$ are confined to the ISM of galaxies.Comment: Accepted in A&A, abstract abridge

Bilateral Breast Involvement In Acute Lymphoblastic-Leukemia - Color Doppler Sonography Findings

WOS: A1995RW13800059PubMed ID: 767695

Radical treatment for hepatic echinococcosis

Background: Hydatid liver surgery is associated with a high incidence of recurrence. Combined medical and surgical treatment should decrease the recurrence rates. Methods: In a retrospective study, 75 patients receiving operative treatment for hepatic echinococcosis with or without albendazole therapy were invited to enter a follow-up survey. Patients were examined clinically, and hydatid serology and B-mode ultrasound were performed. The initial results were evaluated by a panel and patients with equivocal results were further studied with diagnostic aspiration and direct microscopic examination for protoscolices. Results: Thirty-nine patients (52%) responded and 36 were followed up (22 in Group I with operation plus albendazole; 14 in Group 2 with operation alone). Although recurrence could not be excluded in 24 of these patients (18 Group I, 6 Group 2) when the initial results were evaluated, diagnostic aspiration revealed protoscolices in only two of them. One of these patients was excluded from the study because of inapproriate usage of albendazole. The recurrence rate was therefore 5%. Discussion: The recurrence rate in this study is lower than that obtained in our previous experience, but it does not represent a significant benefit for combined ('radical') treatment of echinococcosis. Data obtained from the follow-up studies are confusing for most of the parameters and indicate that the present methods for assessment are unsatisfactory for evaluating the treatment of hepatic echinococcosis

CT findings of abdominal tuberculosis in 12 patients

WOS: 000177873400004PubMed ID: 12204236Our purpose was to evaluate the Computed Tomography (CT) findings of the abdominal tuberculosis (TBC) retrospectively which was diagnosed histopatologically. This study included 12 patients, All patients were evaluated by abdominal CT study. Most findings of CT studies were mesenteric calcified or noncalcified lymphadenopathies, ascites, thickened intestinal wall located on the right lower quadrant of abdomen, thickening of peritoneum, mottled soft-tissue densities in omentum and mesenterium. In addition, one of the patients had bilateral calcified adrenal glands and one of them had calcified mass in adrenal gland. If peritoneal thickening, ascites, abdominal lymphadenophaties and thickened intestinal walls are obtained, TBC should be considered in differential diagnosis in developing countries. (C) 2002 Elsevier Science Ltd. All rights reserved

The potential value of power Doppler ultrasound imaging compared with grey-scale ultrasound findings in the diagnosis of local recurrence after radical prostatectomy

WOS: 000236663500004PubMed ID: 16546462AIM: To determine the value of power Doppler ultrasound (PDUS) imaging during transrectal ultrasonography (TRUS) in detecting local recurrence after radical retropubic prostatectomy (RRP). MATERIALS AND METHODS: Eighteen patients were evaluated in whom local recurrence of prostate cancer was suspected on the basis of elevated serum prostate-specific antigen (PSA) levels (above 0.4 ng/ml) after RRP with no evidence of metastatic disease. Grey-scale TRUS and PDUS-guided biopsies of the vesicourethral anastomosis (VUA) and perianastomotic soft tissues were obtained after TRUS examinations of the prostatic fossa. The ability to detect locally recurrent prostate cancer using grey-scate TRUS alone was compared with TRUS combined with PDUS. RESULTS: Fifteen of the 18 patients (83%) had positive biopsies for local recurrent tumour at histological examination. TRUS atone detected grey-scate abnormalities in 15 of 18 patients (83%), of whom 14 (77%) had positive TRUS-guided biopsies. PDUS during TRUS showed hypervascularity in 14 of 18 patients (77%). Biopsies of these hypervascular regions were positive in all patients (100%). The sensitivity and specificity of TRUS atone in detecting recurrent tumour were 93 and 67%, respectively, with a positive predictive value (PPV) of 93% and a negative predictive value (NPV) of 67%. TRUS combined with PDUS had a sensitivity and specificity of 93 and 100%, respectively, with a PPV and a NPV of 100 and 75%, respectively. (c) 2006 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved