Role of Polyamine-Induced Dimerization of Antizyme in Its Cellular Functions

Funding: This work was supported by grants from the Russian Science Foundation (grant # 17-74-20049—synthesis of C-methylated Spd analogues, ITC studies of dimerization of OAZ1, and frameshifting experiments), the Russian Science Foundation (grant # 19-74-10086—isolation of OAZ1, electrophoresis studies of dimerization of OAZ1), and the Academy of Finland (grants # 292574 and # 315487). Acknowledgments: The authors thank A. Karppinen, A. Korhonen, T. Reponen, M. Salminkoski, and S.D. Negrya for their skillful technical assistance.Peer reviewedPublisher PD

An Improved Neutron Electric Dipole Moment Experiment

A new measurement of the neutron EDM, using Ramsey's method of separated oscillatory fields, is in preparation at the new high intensity source of ultra-cold neutrons (UCN) at the Paul Scherrer Institute, Villigen, Switzerland (PSI). The existence of a non-zero nEDM would violate both parity and time reversal symmetry and, given the CPT theorem, might lead to a discovery of new CP violating mechanisms. Already the current upper limit for the nEDM (|d_n|<2.9E-26 e.cm) constrains some extensions of the Standard Model. The new experiment aims at a two orders of magnitude reduction of the experimental uncertainty, to be achieved mainly by (1) the higher UCN flux provided by the new PSI source, (2) better magnetic field control with improved magnetometry and (3) a double chamber configuration with opposite electric field directions. The first stage of the experiment will use an upgrade of the RAL/Sussex/ILL group's apparatus (which has produced the current best result) moved from Institut Laue-Langevin to PSI. The final accuracy will be achieved in a further step with a new spectrometer, presently in the design phase.Comment: Flavor Physics & CP Violation Conference, Taipei, 200

Precise Measurement of the Pi+ -> Pi0 e+ nu Branching Ratio

Using a large acceptance calorimeter and a stopped pion beam we have made a precise measurement of the rare Pi+ -> Pi0 e+ Nu,(pi_beta) decay branching ratio. We have evaluated the branching ratio by normalizing the number of observed pi_beta decays to the number of observed Pi+ -> e+ Nu, (pi_{e2}) decays. We find the value of Gamma(Pi+ -> Pi0 e+ Nu)/Gamma(total) = [1.036 +/- 0.004(stat.) +/- 0.004(syst.) +/- 0.003(pi_{e2})] x 10^{-8}$, where the first uncertainty is statistical, the second systematic, and the third is the pi_{e2} branching ratio uncertainty. Our result agrees well with the Standard Model prediction.Comment: 4 pages, 5 figures, 1 table, revtex4; changed content; updated analysi

Testing isotropy of the universe using the Ramsey resonance technique on ultracold neutron spins

Physics at the Planck scale could be revealed by looking for tiny violations of fundamental symmetries in low energy experiments. In 2008, a sensitive test of the isotropy of the Universe using has been performed with stored ultracold neutrons (UCN), this is the first clock-comparison experiment performed with free neutrons. During several days we monitored the Larmor frequency of neutron spins in a weak magnetic field using the Ramsey resonance technique. An non-zero cosmic axial field, violating rotational symmetry, would induce a daily variation of the precession frequency. Our null result constitutes one of the most stringent tests of Lorentz invariance to date.Comment: proceedings of the PNCMI2010 conferenc

MEG Upgrade Proposal

We propose the continuation of the MEG experiment to search for the charged lepton flavour violating decay (cLFV) \mu \to e \gamma, based on an upgrade of the experiment, which aims for a sensitivity enhancement of one order of magnitude compared to the final MEG result, down to the $6 \times 10^{-14}$ level. The key features of this new MEG upgrade are an increased rate capability of all detectors to enable running at the intensity frontier and improved energy, angular and timing resolutions, for both the positron and photon arms of the detector. On the positron-side a new low-mass, single volume, high granularity tracker is envisaged, in combination with a new highly segmented, fast timing counter array, to track positron from a thinner stopping target. The photon-arm, with the largest liquid xenon (LXe) detector in the world, totalling 900 l, will also be improved by increasing the granularity at the incident face, by replacing the current photomultiplier tubes (PMTs) with a larger number of smaller photosensors and optimizing the photosensor layout also on the lateral faces. A new DAQ scheme involving the implementation of a new combined readout board capable of integrating the diverse functions of digitization, trigger capability and splitter functionality into one condensed unit, is also under development. We describe here the status of the MEG experiment, the scientific merits of the upgrade and the experimental methods we plan to use.Comment: A. M. Baldini and T. Mori Spokespersons. Research proposal submitted to the Paul Scherrer Institute Research Committee for Particle Physics at the Ring Cyclotron. 131 Page

Effect of Er and Y on Structure and Properties of the Al–Zn–Mg–Cu–Zr Alloy with High Cu Content

Исследовано влияние иттрия и эрбия на фазовый состав и свойства сплава Al–Zn–Mg–Cu–Zr. Формирование диспресоидов c иттрием и эрбием при гомогенизации обеспечивает больший прирост твердости и устойчивость сплава к перестариванию.The effect of yttrium and erbium on phase composition and properties of the Al–Zn–Mg–Cu–Zr alloy was investigated. Formation of the fine dispersoids with yttrium and erbium at homogenization treatment provides a higher hardness increasing and stability during over aging.Работа выполнена при финансовой поддержке Российского научного фонда (проект № 20-79-00305).The work was carried out with the financial support of the Russian science foundation (project No. 20-79-00305)

Моделирование распределения водного эквивалента снежного покрова в тундре с использованием ГИС и данных полевой снегомерной съёмки

An approach for snow water equivalent (SWE) modelling in tundra environments has been developed for the test area on the Yamal peninsula. Detailed mapping of snow cover is very important for tundra areas under continuous permafrost conditions, because the snow cover affects the active layer thickness (ALT) and the ground temperature, acting as a heat-insulating agent. The information concerning snow cover with specific regime of accumulation can support studies of ground temperature distribution and other permafrost related aspects. Рассматривается методика моделирования водного эквивалента снежного покрова, основанная на статистической обработке данных полевой снегомерной съёмки и геоинформационном анализе различных параметров: рельефа, направления ветра, кустарниковой растительности. Установлено, что особенности рельефа в значительной степени влияют на перераспределение снежного покрова. Так, на вогнутых участках толщина снега увеличивается, а на выпуклых – уменьшается, поэтому индекс кривизны поверхности служит эффективным параметром при моделировании толщины снежного покрова на том или ином участке. Между толщиной снежного покрова и индексом кривизны поверхности установлена высокая степень корреляции (R = −0,83). Учёт перераспределения снега ветром очень важен для региона исследования. Чтобы объяснить основные закономерности этого процесса, мы применили механизм введения поправок при индексировании наветренных и подветренных склонов. Для классификации поверхности использована растровая модель экспозиции склонов, построенная на основе цифровой модели рельефа (ЦМР). В соответствии с господствующим направлением ветра положительные значения поправок присваивались подветренным склонам, а отрицательные – наветренным. Установлено, что кустарниковая растительность служит «ловушкой» для перевеваемого ветром снега, однако высота растительности не определяет его толщину, поскольку толщина снега может быть и больше, и меньше высоты стеблей, и зависит она от других факторов.

Measurement of the radiative decay of polarized muons in the MEG experiment

We studied the radiative muon decay $\mu^+ \to e^+\nu\bar{\nu}\gamma$ by using for the first time an almost fully polarized muon source. We identified a large sample (~13000) of these decays in a total sample of 1.8x10^14 positive muon decays collected in the MEG experiment in the years 2009--2010 and measured the branching ratio B($\mu^+ \to e^+\nu\bar{\nu}\gamma$) = (6.03+-0.14(stat.)+-0.53(sys.))x10^-8 for E_e > 45 MeV and E_{\gamma} > 40 MeV, consistent with the Standard Model prediction. The precise measurement of this decay mode provides a basic tool for the timing calibration, a normalization channel, and a strong quality check of the complete MEG experiment in the search for $\mu^+ \to e^+\gamma$ process.Comment: 8 pages, 7 figures. Added an introduction to NLO calculation which was recently calculated. Published versio