271 research outputs found
Chiral Lagrangian with confinement from the QCD Lagrangian
An effective Lagrangian for the light quark in the field of a static source
is derived systematically using the exact field correlator expansion. The
lowest Gaussian term is bosonized using nonlocal colorless bosonic fields and a
general structure of effective chiral Lagrangian is obtained containing all set
of fields. The new and crucial result is that the condensation of scalar
isoscalar field which is a usual onset of chiral symmetry breaking and is
constant in space-time, assumes here the form of the confining string and
contributes to the confining potential, while the rest bosonic fields describe
mesons with the q\bar q quark structure and pseudoscalars play the role of
Nambu-Goldstone fields. Using derivative expansion the effective chiral
Lagrangian is deduced containing both confinement and chiral effects for
heavy-light mesons. The pseudovector quark coupling constant is computed to be
exactly unity in the local limit,in agreement with earlier large N_c arguments.Comment: LaTeX2e, 17 page
The structure and properties of a hypoeutectic silumin subjected to complex electron–ion-plasma processing
The layer-by-layer analysis of structural–phase states and tribological properties of hypoeutectic АК10М2Н-type silumin at the depth up to 170 μm after the complex processing is carried out by the state-of-the-art methods of physical materials science. It involves the electroexplosion alloying with titanium and yttrium-oxide powder in different ratios followed by electron-beam processing.Методами сучасного фізичного матеріалознавства проведено пошарову аналізу структурно-фазових станів і трибологічних властивостей доевтектичного силуміну марки АК10М2Н на глибині до 170 мкм після комплексного оброблення. Воно полягало в електропідривному леґуванні титаном і порошком оксиду ітрію в різних співвідношеннях з подальшим електронно-пучковим обробленням.Методами современного физического материаловедения проведён послойный анализ структурно-фазовых состояний и трибологических свойств доэвтектического силумина марки АК10М2Н на глубине до 170 мкм после комплексной обработки. Она заключалась в электровзрывном легировании титаном и порошком оксида иттрия в разных соотношениях с последующей электронно-пучковой обработкой
Width of Sunspot Generating Zone and Reconstruction of Butterfly Diagram
Based on the extended Greenwich-NOAA/USAF catalogue of sunspot groups it is
demonstrated that the parameters describing the latitudinal width of the
sunspot generating zone (SGZ) are closely related to the current level of solar
activity, and the growth of the activity leads to the expansion of SGZ. The
ratio of the sunspot number to the width of SGZ shows saturation at a certain
level of the sunspot number, and above this level the increase of the activity
takes place mostly due to the expansion of SGZ. It is shown that the mean
latitudes of sunspots can be reconstructed from the amplitudes of solar
activity. Using the obtained relations and the group sunspot numbers by Hoyt
and Schatten (1998), the latitude distribution of sunspot groups ("the Maunder
butterfly diagram") for the 18th and the first half of the 19th centuries is
reconstructed and compared with historical sunspot observations.Comment: 16 pages, 11 figures; accepted by Solar Physics; the final
publication will be available at www.springerlink.co
Analytic Methods in Nonperturbative QCD
Recently developed analytic methods in the framework of the Field Correlator
Method are reviewed in this series of four lectures and results of calculations
are compared to lattice data and experiment. Recent lattice data demonstrating
the Casimir scaling of static quark interaction strongly support the FCM and
leave very little space for all other theoretical models, e.g. instanton
gas/liquid model. Results of calculations for mesons, baryons, quark-gluon
plasma and phase transition temperature demonstrate that new analytic methods
are a powerful tool of nonperturbative QCD along with lattice simulations.Comment: LaTeX, 34 pages; Lectures given at the 13th Indian-Summer School
"Understanding the Structure of Hadrons", August 28 - September 1, 2000,
Prague, Czech Republi
Crystal collimation experiment on 70-GeV proton accelerator
The first proof-of-principle experiment on "crystal collimation" was performed with 70-GeV protons on IHEP accelerator. A bent crystal installed in the ring as a primary element upstream of a collimator has reduced the radiation levels downstream in the accelerator by a factor of two. The measurements agree with Monte Carlo predictions
Использование устройств аспирации тромба при острых окклюзиях коронарных артерий
There were analyzed 38 patients with acute coronary syndrome with ST segment elevation. Every patient was revealed by coronary angiography to have an occlusion in one of the main coronary arteries. The patients were divided in two groups by the technique of percutaneous coronary intervention. In the first group (n = 18) after mechanical recanalisation with wire we used a catheter for thrombus aspiration. Furthermore according to results after coronary angiography these patients underwent either direct stenting or predilatation with further stenting. After mechanical recanalisation in the second group (n = 20) routine stenting with predilatation were performed. The reperfusion quality was evaluated by TIMI scale by the angiography and ST segment decrease during 30 minutes after the intervention. It was statistically proved that adequate reperfusion was achieved in the group with thrombus aspiration catheter.Проанализированы результаты обследования и лечения 38 пациентов с инфарктом миокарда с подъемом сегмента ST. По результатам коронарной ангиографии во всех наблюдениях определялась окклюзия одной из магистральных коронарных артерий. Пациенты были разделены на две группы в зависимости от тактики выполнения чрескожного коронарного вмешательства. В первой группе (n = 18) после механической реканализации проводником в зону окклюзии вводили катетер для аспирации тромба. Далее в зависимости от ангиографического результата выполнялось прямое стентирование поражения или предварительная баллонная ангиопластика с последующим стентированием. Во второй группе (n = 20) после механической реканализации выполнялась баллонная ангиопластика с последующим стентированием. Адекватность реперфузии оценивалась по степени восстановления кровотока по шкале TIMI по результатам коронарной ангиографии и по снижению сегмента ST по данным ЭКГ через 30 минут после окончания вмешательства. При сравнении результатов первой и второй групп установлено, что достоверно чаще в первой группе пациентов удавалось достигнуть адекватной реперфузии
Observation of Non-Exponential Orbital Electron Capture Decays of Hydrogen-Like Pr and Pm Ions
We report on time-modulated two-body weak decays observed in the orbital
electron capture of hydrogen-like Pr and Pm
ions coasting in an ion storage ring. Using non-destructive single ion,
time-resolved Schottky mass spectrometry we found that the expected exponential
decay is modulated in time with a modulation period of about 7 seconds for both
systems. Tentatively this observation is attributed to the coherent
superposition of finite mass eigenstates of the electron neutrinos from the
weak decay into a two-body final state.Comment: 12 pages, 5 figure
Deuteron frozen spin polarized target for nd experiements at the VdG accelerator of Charles University
A frozen spin polarized deuteron target cooled by the 3He/4He dilution
refrigerator is described. Fully deuterated 1,2-propanediol was used as a
target material. Deuteron vector polarization about 40% was obtained for the
target in the shape of a cylinder of 2 cm diameter and 6 cm length. The target
is intended for a study of 3N interactions at the polarized neutron beam
generated by the Van de Graaff accelerator at the Charles University in Prague
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
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