Threshold Resummation for Top-Pair Hadroproduction to Next-to-Next-to-Leading Log

We derive the threshold-resummed total cross section for heavy quark production in hadronic collisions accurate to next-to-next-to-leading logarithm, employing recent advances on soft anomalous dimension matrices for massive pair production in the relevant kinematic limit. We also derive the relation between heavy quark threshold resummations for fixed pair kinematics and the inclusive cross section. As a check of our results, we have verified that they reproduce all poles of the color-averaged q\bar{q} -> t\bar{t} amplitudes at two loops, noting that the latter are insensitive to the color-antisymmetric terms of the soft anomalous dimension.Comment: 18 pages; Expanded discussion, added references. Results unchanged

The first fossil cyphophthalmid harvestman from Baltic amber

The first fossil cyphophthalmid harvestman (Opiliones: Cyphophthalmi) from Palaeogene (Eocene) Baltic amber is described. This is only the third fossil example of this basal harvestman lineage; the others being from the probably slightly younger Bitterfeld amber and the much older, early Cretaceous, Myanmar (Burmese) amber. Although incomplete and lacking most of the appendages, the new Baltic amber fossil can be identified as a female. The somatic characters preserved, especially spiracle morphology and the coxo-genital region, allow it to be assigned with some confidence to the extant genus Siro Latreille, 1796 (Sironidae). This fossil is formally described here as Siro balticus sp. nov. It resembles modern North American Siro species more than modern European ones, and can be distinguished principally on its relatively large size and the outline form of the body

CHARACТERISТICS OF INFLUENZA VIRUS STRAINS, ISOLATED IN 1963 IN VARNA

In March 1963, 7 strains of influenza virus type А2 were isolated at the virological laboratory of the Higher Medical Institute - Vaгna from local inhabitants, suffering from influenza. Their etiologic signif icance in the disorders, observed in this period, was proved bу examination of the haemagglutination inhibtion test (Н.I.Т.) bу means of paired samples оfblооd sera, obtained from sick individuals as well as from those who have already suffered fгom the disease. In some оf the examined individuals а 4 аnd more fold rise in antibody titre was established.We set ourselves the task to investigate the antigenic structure of the isolated inflluenza virus stгains

Comment on Resummation of Mass Distribution for Jets Initiated by Massive Quarks

We compute in the heavy quark effective theory the soft coefficient D_2 entering the resummation of next-to-next-to-leading threshold logarithms for jets initiated by a quark with a small mass compared to the hard scale of the process. We find complete agreement with a previous computation in full QCD. Contrary to our previous guess, this coefficient turns out to be different from that one entering heavy flavor decay or heavy flavor fragmentation.Comment: 5 pages, no figures; minor changes, references added, version accepted in Phys.Lett.

Extremes of geometric variables with applications to branching processes

We obtain limit theorems for the row extrema of a triangular array of zero-modified geometric random variables. Some of this is used to obtain limit theorems for the maximum family size within a generation of a simple branching process with varying geometric offspring laws.Comment: 12 pages, some proofs are added to the published versio

Soft-Gluon Resummation for Heavy Quark Production in Charged-Current Deep Inelastic Scattering

We study soft-gluon radiation for heavy quark production in charged-current Deep Inelastic Scattering processes. We resum large-x contributions to the MSbar coefficient function to next-to-leading logarithmic accuracy and present results for charm quark structure functions for several values of the ratio m_c/Q. The effect of the resummation turns out to be visible, especially at small Q^2, and the results exhibit very little dependence on factorization and renormalization scales. The impact of our calculation on structure function measurements at NuTeV and HERA experiments is discussed.Comment: 21 pages, 7 figure

Microbiological characterization of Streptococcus pneumoniae and non-typeable Haemophilus influenzae isolates as primary causes of acute otitis media in Bulgarian children before the introduction of conjugate vaccines

BACKGROUND: Pneumococcal and Haemophilus influenzae type b (Hib) vaccines were introduced in our national immunisation program in April 2010. The aims of this retrospective, laboratory-based study were to determine the serotypes and antibiotic resistance of Streptococcus pneumoniae and H. influenzae isolates from middle ear fluid (MEF) collected before the introduction of immunization. METHODS: S. pneumoniae (n = 128) and H. influenzae (n = 40) strains isolated from MEF of children with AOM between 1994 and 2011 were studied. MICs were determined by a microdilution assay. Serotyping of S. pneumoniae was done by Quellung method and PCR capsular typing was used for H. influenzae. Macrolide resistance genes were detected by PCR for erythromycin resistant S. pneumoniae (ERSP). DNA sequencing of ftsI gene was performed for ampicillin nonsusceptible H. influenzae. RESULTS: The most common serotypes found among children with pneumococcal AOM were 19 F (20.3%), 6B (15.6%), and 19A (10.9%). The potential coverage rates by the PCV7, PCV10 and PCV13 of children aged < 5 years were 63.6%, 66.4% and 85.5%, respectively. Reduced susceptibility to oral penicillin was seen in 68.1%; resistance to erythromycin was 46.9%. We found erm(B) gene in 56.7% of the ERSP, mef(E) gene in 25%; 15% harbored both genes erm(B) + mef(E) and 3.3% had mutations of L4 ribosomal protein. Of the 40 H. influenzae isolates 97.5% were nontypeable. Nonsusceptibility to ampicillin occurred in 25%. Ampicillin resistance groups were: β-lactamase-positive ampicillin resistant (BLPAR) strains (10%), β-lactamase-negative ampicillin resistant (BLNAR) strains (12.5%) and β-lactamase-positive amoxicillin-clavulanate resistant (BLPACR) strains (2.5%). Among BLNAR and BLPACR most of the isolates (5/6) belonged to group II, defined by the Asn526Lys substitution. CONCLUSIONS: The levels of antibiotic resistance among S. pneumoniae and H. influenzae causing severe AOM in children are high in our settings. The existence of multidrug-resistant S. pneumoniae serotype 19A is of particular concern. The rate of BLNAR and BLPACR strains among H. influenzae isolates was 15%

Synthesis of Improved Catalytic Materials for High-Temperature Water-gas Shift Reaction

In this investigation, we report the preparation and characterization of Co-, Cu- and Mn-substituted iron oxide catalytic materials supported on activated carbon. Co-precipitation method and low temperature treatment were used for their synthesis. The influence of chemical composition, stoichiometry, particle size and dispersity on their catalytic activity was studied. Samples were characterized in all stages of their co-precipitation, heating and spend samples after catalytic tests. The obtained results from room and low temperature Mössbauer spectroscopy were combined with analysis of powder X-ray diffraction patterns (XRD). They revealed the preparation of nano-sized iron oxide materials supported on activated carbon. Relaxation phenomena were registered also for the supported phases. The catalytic performance in the water-gas shift reaction was studied. The activity order was as follows: Cu0.5Fe2.5O4 > Co0.5Fe2.5O4 > Mn0.5Fe2.5O4. Catalytic tests demonstrated very promising results and potential application of studied samples due to their cost-effective composition