Three-dimensional structure of Serratia marcescens nuclease at 1.7 Å resolution and mechanism of its action

AbstractThe three-dimensional crystal structure of Serratia marcescens (Sm) nuclease has been refined at 1.7 Å resolution to the R-factor of 17.3% and R-free of 22.2%. The final model consists of 3678 non-hydrogen atoms and 443 water molecules. The analysis of the secondary and the tertiary structures of the Sm nuclease suggests a topology which reveals essential inner symmetry in all the three layers forming the monomer. We propose the plausible mechanism of its action based on a concerted participation of the catalytically important amino acid residues of the enzyme active site

АРТРОДЕЗИРОВАНИЕ ГОЛЕНОСТОПНОГО СУСТАВА С ИСПОЛЬЗОВАНИЕМ ТРЕХ СПОНГИОЗНЫХ ВИНТОВ

Purpose — to evaluate the efficiency of the proposed method of arthrodesis by three cancellous screws in patients with posttraumatic arthrosis of the ankle joint.Materials and Methods. After removal of talus and tibia cartilage and autografting the proposed method features placement of foot into the optimal position and fixation of the ankle joint with three cancellous screws. 23 patients with posttraumatic ankle deformity arthrosis of grades III–IV underwent surgery according to the described procedure. Condition of all patients prior to and after the surgery was evaluated using the international ankle and rear foot assessment scale of the American Orthopedic Society of the Foot and Ankle (AOFAS).Results. In 20 patients (88%) the ankle ankylosis was reported within 2.5 months, which was confirmed by X-ray examination. In 2 patients (8%) the ankylosis took place in the period up to 4 months. Loss of the correct position of the foot with screws migration was reported in one patient (4%). The authors observed that patients with postoperative deviation of the tibiotalar angle not exceeding 5 degrees as compared to a healthy limb demonstrated the best functional outcomes.Conclusion. The suggested technique ensures a secure fixation of talus in a predetermined position, a single-step compression between the closed joint surfaces and allows an early effective rehabilitation.Цель исследования — оценить эффективность предложенного способа артродезирования тремя спонгиозными винтами у пациентов с посттравматическим деформирующим артрозом голеностопного сустава.Материал и методы. Особенность методики заключается в том, что после удаления хряща таранной и большеберцовой костей, оригинальной пластики аутологичной костью стопу выводят в оптимальное положение и фиксируют голеностопный сустав тремя спонгиозными винтами. Предложенным способом было прооперировано 23 пациента с посттравматическим деформирующим артрозом голеностопного сустава III–IV степени. Состояние всех пациентов до и после операции оценивали с использованием шкалы оценки голеностопного сустава и заднего отдела стопы, принятой Американским ортопедическим обществом стопы и голеностопного сустава (AOFAS).Результаты. У 20 (88%) больных костный анкилоз голеностопного сустава был достигнут в срок до 2,5 мес., что было подтверждено рентгенологическим исследованием, у 2 (8%) больных анкилоз состоялся в срок до 4 мес. У одного больного (4%) возникла потеря корректного положения стопы с миграцией винтов. Пациенты, у которых отклонение таранно-большеберцового угла не превышало 5° по сравнению со здоровой конечностью после операции, имели наилучшие функциональные результаты.Заключение. Предложенный способ обеспечивает надежное удержание таранной кости в заданном положении, одномоментную компрессию между замыкаемыми поверхностями сустава и позволяет начать раннюю и эффективную реабилитаци

Anisotropic flows from colour strings: Monte-Carlo simulations

By direct Monte-Carlo simulations it is shown that the anisotropic flows can be successfully described in the colour string picture with fusion and percolation provided anisotropy of particle emission from the fused string is taken into account. Quenching of produced particles in the strong colour field of the string is the basic mechanism for this anisotropy. The concrete realization of this mechanism is borrowed from the QED. Due to dependence of this mechanism on the external field strength the found flows grow with energy, with values for $v_2$ at LHC energies greater by ~15% than at RHIC energies.Comment: New version with a non-static distribution of string

On the structure of the B\"acklund transformations for the relativistic lattices

The B\"acklund transformations for the relativistic lattices of the Toda type and their discrete analogues can be obtained as the composition of two duality transformations. The condition of invariance under this composition allows to distinguish effectively the integrable cases. Iterations of the B\"acklund transformations can be described in the terms of nonrelativistic lattices of the Toda type. Several multifield generalizations are presented

On Asymptotic Expansion in the Random Allocation of Particles by Sets

We consider a scheme of equiprobable allocation of particles into cells by sets. The Edgeworth type asymptotic expansion in the local central limit theorem for a number of empty cells left after allocation of all sets of particles is derived.Comment: 15 page

Instanton Corrections to Quark Form Factor at Large Momentum Transfer

Within the Wilson integral formalism, we discuss the structure of nonperturbative corrections to the quark form factor at large momentum transfer analyzing the infrared renormalon and instanton effects. We show that the nonperturbative effects determine the initial value for the perturbative evolution of the quark form factor and attribute their general structure to the renormalon ambiguities of the perturbative series. It is demonstrated that the instanton contributions result in the finite renormalization of the next-to-leading perturbative result and numerically are characterized by a small factor reflecting the diluteness of the QCD vacuum within the instanton liquid model.Comment: Version coincident with the journal publication, 9 pages; REVTe

The spectrum features of UHECRs below and surrounding GZK

The energy spectrum of UHECRs is discussed on the basis of the Yakutsk array database analysis. In the region E=0.1 to 30 EeV the showers are detected under trigger-500, while at energies above 30 EeV the whole acceptance area for trigger-1000 is used in order to utilize all the data available in the region of GZK cutoff.Comment: Invited talk at CRIS2004: GZK and surroundings, Catania, Italy, 31.05.04. To appear in Nucl. Phys. B Proc. Supp

Quark structure of the pion and pion form factor

We consider the pion structure in the region of low and moderately high momentum transfers: at low $Q^2$, the pion is treated as a composite system of constituent quarks; at moderately high momentum transfers, $Q^2=10\div25\;GeV^2$, the pion \ff is calculated within perturbative QCD taking into account one--gluon hard exchange. Using the data on pion \ff at $Q^2<3\;GeV^2$ and pion axial--vector decay constant, we reconstruct the pion \wf in the soft and intermediate regions. This very wave function combined with one--gluon hard scattering amplitude allows a calculation of the pion \ff in the hard region $Q^2=10\div25\;GeV^2$. A specific feature of the reconstructed pion \wf is a quasi--zone character of the $q\bar q$--excitations. On the basis of the obtained pion \wf and the data on deep inelastic scattering off the pion, the valence quark distribution in a constituent quark is determined.Comment: 22 pages, latex, 14 figure