Search results for "Ih"
showing 10 items of 9382 documents
Psihohigiēnas nozīme cilvēka personības attīstībā
1994
Measurement of the branching ratio and an upper limit on
1995
Abstract Using 1.45 million hadronic Z decays collected by the ALEPH experiment at LEP, the b → τ − ν - τ X branching ratio is measured to be 2.75 ± 0.30 ± 0.37%. In addition an upper limit of 1.8 × 10 −3 at 90% confidence level is placed upon the exclusive branching ratio of B − → τ − ν - τ . These measurements are consistent with SM expectations, and put the constraint tan β M h ± GeV −1 at 90% confidence level on all Type II two Higgs doublet models (such as the MSSM).
Updated measurement of the τ lepton lifetime
1997
A new measurement of the mean lifetime of the tau lepton is presented. Three different analysis methods are applied to a sample of 90000 tau pairs, collected in 1993 and 1994 with the ALEPH detector at LEP. The average of this measurement and those previously published by ALEPH is tau_tau = 290.1 +- 1.5 +- 1.1 fs.
Measurement of the AtmosphericνeSpectrum with IceCube
2015
We present a measurement of the atmospheric $\nu_e$ spectrum at energies between 0.1 TeV and 100 TeV using data from the first year of the complete IceCube detector. Atmospheric $\nu_e$ originate mainly from the decays of kaons produced in cosmic-ray air showers. This analysis selects 1078 fully contained events in 332 days of livetime, then identifies those consistent with particle showers. A likelihood analysis with improved event selection extends our previous measurement of the conventional $\nu_e$ fluxes to higher energies. The data constrain the conventional $\nu_e$ flux to be $1.3^{+0.4}_{-0.3}$ times a baseline prediction from a Honda's calculation, including the knee of the cosmic-…
Large numbers of cold positronium atoms created in laser-selected Rydberg states using resonant charge exchange
2016
Lasers are used to control the production of highly excited positronium atoms (Ps*). The laser light excites Cs atoms to Rydberg states that have a large cross section for resonant charge-exchange collisions with cold trapped positrons. For each trial with 30 million trapped positrons, more than 700 000 of the created Ps* have trajectories near the axis of the apparatus, and are detected using Stark ionization. This number of Ps* is 500 times higher than realized in an earlier proof-of-principle demonstration (2004 Phys. Lett. B 597 257). A second charge exchange of these near-axis Ps* with trapped antiprotons could be used to produce cold antihydrogen, and this antihydrogen production is e…
Ar amīniem modificētu 1,4-dihidropiridīna atvasinājumu sintēze un īpašību pētījumi
2016
Sintezēts nekomerciāli pieejamais didodecil 2,6-bis(brometil)-4-fenil-1,4-dihidropiridīna-3,5-dikarboksilāts. Tam veikta broma aizvietošana 2,6-vietās ar dažādiem amīniem, iegūstot desmit jaunus oriģinālus savienojumus. Dots jaunsintezēto savienojumu fiziko-ķīmisko īpašību raksturojums, noteikta sintezēto savienojumu reducējošās kapacitātes aktivitāte, izmantojot fosformolibdēna kompleksa metodi, veikta antiradikālās aktivitātes noteikšana ar 1,1-difenil-2-pikrilhidrazil brīvo radikāļu metodi. Noskaidrots, ka no visiem jaunsintezētajiem savienojumiem, visaktīvākais ir didodecil 2,6-bis[(5-fluoro-2,6-diokso-3-tetrahidrofurān-2-il-pirimidīn-1-il)metil]-4-fenil-1,4-dihidropiridīna-3,5-dikarbok…
1,4-Dihidropiridīnu atvasinājumu nanodaļiņu toksiskuma novērtējums mikroorganismos
2017
1,4 Dihidropiridīnu (1,4 DHP) atvasinājumi ir plaša organisko vielu grupa, kurā arvien tiek sintezēti jauni savienojumi ar plašām pielietojuma iespējām. Jauno savienojumu toksicitātes raksturojums ir nepieciešams, lai paredzētu to pielietojuma iespējas un novērtētu to iedarbību uz vidi un dzīvajiem organismiem. Darbā pielāgota universāla un efektīva atšķaidījumu metode, lai noteiktu deviņu katjono amfifilo 1,4 DHP atvasinājumu toksicitātes robežkoncentrācijas sešām baktērijām un vienam raugam. Papildus noteikta 1,4 DHP atvasinājumu ietekme uz iekššūnas ATP daudzumu, skābekļa patēriņa ātrumu un etīdija bromīda transportu šūnās. Noskaidrojot toksicitātes robežkoncentrācijas un gūstot ieskatu …
A butterfly like motion as a clue to the photophysics of thioxanthone
2006
Abstract A theoretical, quantum-chemical study of the thioxanthone (TX) molecule has been performed at the MP2 and CASPT2 levels of theory. Geometries, absorption energies, and transition and state properties have been investigated. Two conformers have been found very close in energy with planar (P) and non-planar (NP) structures, the latter characterized by a dihedral angle θ = 173.3° representing the bend of the side benzene rings and an out-of-plane angle ϕ = 4° of the C O bond. Large changes in the relative positions and properties of the two low-lying electronic absorption bands, ππ * and nπ * , are computed when changing the conformation. As a consequence of the analysis of the TX a…
New exotic beams from the SPIRAL 1 upgrade
2018
Since 2001, the SPIRAL 1 facility has been one of the pioneering facilities in ISOL techniques for reaccelerating radioactive ion beams: the fragmentation of the heavy ion beams of GANIL on graphite targets and subsequent ionization in the Nanogan ECR ion source has permitted to deliver beams of gaseous elements (He, N, O, F, Ne, Ar, Kr) to numerous experiments. Thanks to the CIME cyclotron, energies up to 20 AMeV could be obtained. In 2014, the facility was stopped to undertake a major upgrade, with the aim to extend the production capabilities of SPIRAL 1 to a number of new elements. This upgrade, which is presently under commissioning, consists in the integration of an ECR booster in the…