Sofia University

About: Sofia University is a education organization based out in Sofia, Bulgaria. It is known for research contribution in the topics: Large Hadron Collider & Laser. The organization has 8533 authors who have published 15730 publications receiving 306320 citations. The organization is also known as: University of Sofia & BFUS.

Search for Flavor-Changing Neutral Currents in Top-Quark Decays $t \to Zq$ in $pp$ Collisions at $\sqrt{s}=8$ TeV

Abstract: A search for flavor-changing neutral currents in top-quark decays t to Zq is performed in events produced from the decay chain t t-bar to Zq+Wb, where both vector bosons decay leptonically, producing a final state with three leptons (electrons or muons). A dataset collected with the CMS detector at the LHC is used, corresponding to an integrated luminosity of 19.7 inverse femtobarns of proton-proton collisions at a center-of-mass energy of 8 TeV. No excess is seen in the observed number of events relative to the standard model prediction; thus no evidence for flavor-changing neutral currents in top-quark decays is found. A combination with a previous search at 7 TeV excludes a t to Zq branching fraction greater than 0.05% at the 95% confidence level.

Aqueous and Serum Interferon γ, Interleukin (IL) 2, IL-4, and IL-10 in Patients With Uveitis

Abstract: Objective To determine the cytokine profile in aqueous humor and peripheral blood from patients with uveitis. Methods Cytokines (interferon [IFN]–γ, interleukin [IL] 2, IL-4, and IL-10) were measured in aqueous humor and peripheral blood samples from 23 patients with uveitis and 16 patients undergoing operation for uncomplicated cataracts (control group) by means of an enzyme-linked immunosorbent assay. Results Aqueous and serum samples from patients with uveitis showed higher levels of IFN-γ and IL-2 than those of controls ( P P =.002). No differences were found between uveitis and control groups for aqueous and serum IL-4 or aqueous IL-10 levels. In patients with uveitis, IFN-γ levels were significantly higher in serum than aqueous ( P P r =0.44; P =.03). Conclusions Aqueous and serum levels of IFN-γ and IL-2 were elevated in patients with uveitis, suggesting a predominantly type 1 response (high IFN-γ and low IL-4 levels). Elevated serum IFN-γ level seems to predispose the patient to more serious loss of vision.

Multilocular Cystic Renal Cell Carcinoma

Abstract: The 2004 World Health Organization (WHO) classification of kidney tumors recognizes multilocular cystic renal cell carcinoma (MCRCC) as a rare variant of clear cell renal cell carcinoma with a good prognosis. Available information on its clinical significance is limited. The study cohort included 45 MCRCC cases classified according to 2004 WHO criteria obtained through a multi-institutional international search. Most patients had unilateral MCRCC with no side predominance that was found incidentally; 62% were men, but women had tumors at an earlier age ( P = .385). MCRCC occurred slightly more often in men than in women (1.7:1). At diagnosis, 82% of patients had stage T1 and 16%, stage T2; 1 patient had stage T3. The Fuhrman grade was 1 (62%) or 2 (38%), with smaller tumors (≤4 cm) most likely Fuhrman grade 1 ( P = .911). All 45 patients were alive with no evidence of disease at mean follow-up of 66.1 months, confirming an extremely good prognosis after surgery and a 5-year disease-specific survival rate of 100%. To rename this tumor as multilocular cystic renal cell neoplasm of low malignant potential might help urologists approach the patients conservatively.

Proton-proton correlations observed in two-proton radioactivity of 94Ag.

Abstract: The stability and spontaneous decay of naturally occurring atomic nuclei have been much studied ever since Becquerel discovered natural radioactivity in 1896. In 1960, proton-rich nuclei with an odd or an even atomic number Z were predicted to decay through one- and two-proton radioactivity, respectively. The experimental observation of one-proton radioactivity was first reported in 1982, and two-proton radioactivity has now also been detected by experimentally studying the decay properties of 45Fe (refs 3, 4) and 54Zn (ref. 5). Here we report proton-proton correlations observed during the radioactive decay of a spinning long-lived state of the lightest known isotope of silver, 94Ag, which is known to undergo one-proton decay. We infer from these correlations that the long-lived state must also decay through simultaneous two-proton emission, making 94Ag the first nucleus to exhibit one- as well as two-proton radioactivity. We attribute the two-proton emission behaviour and the unexpectedly large probability for this decay mechanism to a very large deformation of the parent nucleus into a prolate (cigar-like) shape, which facilitates emission of protons either from the same or from opposite ends of the 'cigar'.