Molecular cloning, sequencing and sequence analysis of Thermus thermophilus tyrosyl-tRNA synthetase

The gene encoding tyrosyl-tRNA synthetase (TyrRS) from the extreme thermophilic eubacterium T. thermophilus HB27 has been cloned and sequenced. The open reading frame encodes a polypeptide chain of 432 amino acid residues in length (molecular mass 48717 Da). Comparison of the amino acid sequence of the T. thermophilus TyrRS (TyrRSTT) with those of TyrRS from various organisms shows that T. thermophilus enzyme shares a branch in the philogenetic tree of eubacterial TyrRSs with the enzymes from Aquifex aeolicus, Deinococcus radiodurans, Haemophilus influenzae and Helicobacter pyroly (40-57 % amino acid identity), distinct from the branch containing Esherichia coli, Chlamydia trachomatis and Bacillus stearothermophilus, for example (24–28 % amino acid identity). The TyrRS active site domain is highly conserved, whereas a C-terminal tRNA binding domain contains only few conserved residues. But even in the active site exists one very important difference between the two groups of bacterial TyrRSs: Lys-41 in TyrRSTT (and in TyrRS from many human pathogenic bacteria) is conserved as a tyrosine in another group of bacterial TyrRSs and eukaryotic sequences including human. This knowledge could be exploited in the design of new antibiotics.Клоновано та визначено нуклеотидну послідовність гена, що кодує тирозил-тРНК синтетазу (TyrRS) із екстремальнотермофільної еубактеріХ Т. thermophilus НВ27 (TyrRSTT). Відкрита рамка зчитування кодує поліпептидний ланцюг до­вжиною 432 амінокислотних залишки (молекулярна маса 48717 Да). Порівняння амінокислотної послідовності TyrRSTT з відповідними послідовностями інших організмів виявило, що фермент із Т. thermophilus належить до тієї ж гілки філо­генетичного дерева еубактеріальних TyrRS, що й ферменти із Aquifex aeolicus, Deinococcus radiodurans, Haemophilus influenzae і Helicobacter pyroly (ідентичність 40–57 %), але не до тієї, до якої належать, наприклад, Escherichia coli, Chlamydia tracho­matis і Bacillus stearothermophilus (24–28 % ідентичності). Амінокислотна послідовність каталітичного домену висококонсервативна, тоді як тРНК-зв'язувальний С-кінцевий домен містить лише невелику кількість консервативних залишків. Але навіть в активному центрі існує важлива відмінність між двома групами еубактеріальних TyrRS: залишок Lys-41 в TyrRSTT (і в TyrRS із багатьох патогенних бактерій людини) представлений консервативним залишком тирозину в бак­теріальних TyrRS іншої групи, а також еукаріотичних TyrRS, включаючи людину. Ця відмінність може бути використана при створенні нових антибіотиків.Клонирован ген, кодирующий тирозил-тРНК синтетазу (TyrRS) из экстремально термофильной эубактерии Т. ther­mophilus НВ27 (TyrRSTT), и определена его нуклеотидная последовательность. Открытая рамка считывания кодирует полипептидную цепь длиной 432 аминокислотных остатка (молекулярная масса 448717 Да). Сравнение аминокислотных последовательностей TyrRSTT с соответствующими последвательностями из других организмов выявило, что фермент из Т. thermophilus относится к той же ветви филогенетиче­ского древа эубактериальных TyrRS, что и ферменты из Aquifex aeolicus, Deinococcus radiodurans, Haemophilus influenzae и Helicobacter pyroly (идентичность 40–57 %), но не к той, к которой принадлежат, например, Escherichia coli, Chlamydia trachomatis и Bacillus stearothermophilus (24–28 % идентично­сти). Аминокислотная последовательность каталитического домена высококонсервативна, в то время как тРНК-связывающий С-концевой домен содержит лишь несколько консерва­тивных остатков. Однако даже в последовательности актив­ного центра отмечено важное различие между двумя группами эубактериальных TyrRS: остаток Lys-41 в TyrRSTT (и в TyrRS из многих патогенных бактерий человека) представлен консервативным остатком тирозина в бактериальных TyrRS другой группы, а также в TyrRS эукариот, включая человека Это отличие может быть использовано при создании новых антибиотиков

Capture and transport of macroparticles in curved plasma duct at low magnetic field in the presence of an electron beam

The possibility of the macroparticles transport through a magnetic separator due to their capture by the electric field generated inside the duct becomes possible. The conditions are obtained under which transport of the macroparticles by the negative space charge is investigated. It is shown that if there is a space charge in the plasma duct then the interaction of positively charged macroparticles and the negative space charge takes place and as a result, capturing of the macroparticle through the magnetic separator takes place.Изучена возможность транспортировки макрочастиц (МЧ) через магнитный сепаратор в результате их захвата электрическим полем, созданным отрицательным пространственным зарядом. Показано, что при условии существования пространственного заряда в плазмоводе происходит взаимодействие положительно заряженной МЧ и отрицательного пространственного заряда, в результате чего возможно удержание МЧ внутри плазмовода. Определены условия, при которых происходит траспортировка МЧ через сепаратор.Досліджено можливість транспортування макрочастинок (МЧ) крізь магнітний сепаратор у результаті їх захоплення електричним полем, що створюється від’ємним просторовим зарядом. Показано, що за умови існування просторового заряду в плазмоводі відбувається взаємодія позитивно зарядженої МЧ та негативного просторового заряду, внаслідок чого стає можливим утримання МЧ всередині плазмовода. Здобуто умови, за яких відбувається транспортування МЧ крізь магнітний сепаратор

New Approach to GUTs

We introduce a new string-inspired approach to the subject of grand unification which allows the GUT scale to be small, \lesssim 200 TeV, so that it is within the reach of {\em conceivable} laboratory accelerated colliding beam devices. The key ingredient is a novel use of the heterotic string symmetry group physics ideas to render baryon number violating effects small enough to have escaped detection to date. This part of the approach involves new unknown parameters to be tested experimentally. A possible hint at the existence of these new parameters may already exist in the EW precision data comparisons with the SM expectations.Comment: 8 pages; improved text and references, note added; extended text, 1 figure added; extended text for publication in Eur. Phys. Journal

Double volume reflection of a proton beam by a sequence of two bent crystals

The doubling of the angle of beam deflection due to volume reflection of protons by a sequence of two bent silicon crystals was experimentally observed at the 400 GeV proton beam of the CERN SPS. A similar sequence of short bent crystals can be used as an efficient primary collimator for the Large Hadron Collider

Demonstration of the temporal matter-wave Talbot effect for trapped matter waves

We demonstrate the temporal Talbot effect for trapped matter waves using ultracold atoms in an optical lattice. We investigate the phase evolution of an array of essentially non-interacting matter waves and observe matter-wave collapse and revival in the form of a Talbot interference pattern. By using long expansion times, we image momentum space with sub-recoil resolution, allowing us to observe fractional Talbot fringes up to 10th order.Comment: 17 pages, 7 figure

Kaon Production and Kaon to Pion Ratio in Au+Au Collisions at \snn=130 GeV

Mid-rapidity transverse mass spectra and multiplicity densities of charged and neutral kaons are reported for Au+Au collisions at \snn=130 GeV at RHIC. The spectra are exponential in transverse mass, with an inverse slope of about 280 MeV in central collisions. The multiplicity densities for these particles scale with the negative hadron pseudo-rapidity density. The charged kaon to pion ratios are $K^+/\pi^- = 0.161 \pm 0.002 {\rm (stat)} \pm 0.024 {\rm (syst)}$ and $K^-/\pi^- = 0.146 \pm 0.002 {\rm (stat)} \pm 0.022 {\rm (syst)}$ for the most central collisions. The $K^+/\pi^-$ ratio is lower than the same ratio observed at the SPS while the $K^-/\pi^-$ is higher than the SPS result. Both ratios are enhanced by about 50% relative to p+p and $\bar{\rm p}$+p collision data at similar energies.Comment: 6 pages, 3 figures, 1 tabl

Phi meson production in Au+Au and p+p collisions at sqrt (s)=200 GeV

We report the STAR measurement of Phi meson production in Au+Au and p+p collisions at sqrt (s)=200 GeV. Using the event mixing technique, the Phi spectra and yields are obtained at mid-rapidity for five centrality bins in Au+Au collisions and for non-singly-diffractive p+p collisions. It is found that the Phi transverse momentum distributions from Au+Au collisions are better fitted with a single-exponential while the p+p spectrum is better described by a double-exponential distribution. The measured nuclear modification factors indicate that Phi production in central Au+Au collisions is suppressed relative to peripheral collisions when scaled by the number of binary collisions. The systematics of versus centrality and the constant Phi/K- ratio versus beam species, centrality, and collision energy rule out kaon coalescence as the dominant mechanism for Phi production.Comment: 6 pages, 3 figures, submitted to Phys. Rev. Let

Azimuthal anisotropy at RHIC: the first and fourth harmonics

We report the first observations of the first harmonic (directed flow, v_1), and the fourth harmonic (v_4), in the azimuthal distribution of particles with respect to the reaction plane in Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC). Both measurements were done taking advantage of the large elliptic flow (v_2) generated at RHIC. From the correlation of v_2 with v_1 it is determined that v_2 is positive, or {\it in-plane}. The integrated v_4 is about a factor of 10 smaller than v_2. For the sixth (v_6) and eighth (v_8) harmonics upper limits on the magnitudes are reported.Comment: 6 pages with 3 figures, as accepted for Phys. Rev. Letters The data tables are at http://www.star.bnl.gov/central/publications/pubDetail.php?id=3

Observation of focusing of 400 GeV/c proton beam with the help of bent crystals

The results of observation and studies of focusing of 400 GeV/ c proton beam with the help of bent single crystals are presented. Two silicon crystals have been used in the measurements. The focal length of the first and second crystals is found to be 1.48 m and 0.68 m, respectively. The mean square size of the horizontal profile in the focus was 3.1 and 4.3 times as small as at the exit of the crystals

Results of measurements of the analyzing powers for polarized neutrons on C, CH <inf>2</inf> and Cu targets for momenta between 3 and 4.2 GeV/c

The analyzing powers for neutron charge exchange nA → pX reactions on nuclei have been measured on C, CH2 and Cu targets at incident neutron momenta 3.0 - 4.2 GeV/c by detecting one charged particle in forward direction. The polarized neutron measurements are the first of their kind. The experiment was performed using the Nuclotron accelerator in JINR Dubna, where polarized neutrons and protons were obtained from breakup of a polarized deuteron beam which has a maximum momentum of 13 GeV/c. The polarimeter ALPOM2 was used to obtain the analyzing power dependence on the transverse momentum of the final-state nucleon. These data have been used to estimate the figure of merit of a proposed experiment at Jefferson Laboratory to measure the recoiling neutron polarization in the quasi-elastic 2H(e, e'n) reaction, which yields information on the charge and magnetic elastic form factors of the neutron