443 research outputs found
Drinfeld Twists and Algebraic Bethe Ansatz of the Supersymmetric t-J Model
We construct the Drinfeld twists (factorizing -matrices) for the
supersymmetric t-J model. Working in the basis provided by the -matrix (i.e.
the so-called -basis), we obtain completely symmetric representations of the
monodromy matrix and the pseudo-particle creation operators of the model. These
enable us to resolve the hierarchy of the nested Bethe vectors for the
invariant t-J model.Comment: 23 pages, no figure, Latex file, minor misprints are correcte
Cognitive Ability and Cardiovascular Control in Intellectually and Developmentally Disabled People
Earlier, we examined positive effects of hyperoxic air on the cognitive ability of intellectually
and developmentally disabled people (IDDP). In this study, correlation between cognitive
performance in the visual matching task and heart rate (HR) was investigated under normal
air conditions. Eighteen men (mean age 28.7 ± 5.0 year) and 22 women (mean age 35.5 ± 6.9
year) with an assessed disability level of 2.3 ± 0.6 participated. The experiment consisted of
three phases, a total of 7 min, including the rest (3 min), control (2 min), and visual matching
task 2 min phases. The HR in visual matching task phase increased, compared to those in the
rest and control phases. The cognitive ability in the visual matching task correlated with the
HR values; the response time showed a negative correlation with HR, while the accuracy rate
showed a positive correlation. Thus, adaptive changes in cardiovascular regulation probably
related to cognitive efforts and emotional excitation should be considered a noticeable factor
influencing brain supply with oxygen in IDDP (similarly to healthy people). The result of this
study agrees with the earlier obtained indications that hyperoxic air can positively affect the
cognitive performance in IDDP.Раніше ми вивчали позитивні впливи повітря, збагаченого
киснем, на когнітивні здатності людей з недостатнім інтелектуальним розвитком (НІР). У нашій роботі ми досліджували кореляцію між показниками когнітивної активності в
тесті візуальної відповідності та частотою серцевих скорочень (ЧСС) у таких суб’єктів в умовах дихання нормальним
повітрям. У тестах брали участь 18 чоловіків (середній вік
28.7 ± 5.0 року) та 22 жінки (35.5 ± 6.9 року) з оцінкою рівня
інтелектуального розвитку 2.3 ± 0.6. Експеримент (загальна
тривалість 7 хв) складався з трьох фаз: стан розслаблення
(3 хв), контроль (2 хв) та тест візуальної відповідності
(2 хв). Величини ЧСС у межах цього тесту порівняно з величинами в умовах розслаблення й контролю зростали. Показники когнітивних здібностей корелювали з величинами
ЧСС; кореляція часу відповіді була негативною, а точності відповіді – позитивною. Отже, адаптивні зміни регуляції
серцево-судинної системи, мабуть, пов’язані з когнітивними
зусиллями та емоційним збудженням, є істотним фактором,
який впливає на постачання мозку киснем у людей із НІР
(як і у здорових людей). Результати нашої роботи узгоджуються з отриманими раніше свідоцтвами про те, що дихання
повітрям, збагаченим киснем, позитивно впливає на когнітивні можливості людей із НІР
Correlations Between Charge Ordering and Local Magnetic Fields in Overdoped YBaCuO
Zero-field muon spin relaxation (ZF-SR) measurements were undertaken on
under- and overdoped samples of superconducting YBaCuO to
determine the origin of the weak static magnetism recently reported in this
system. The temperature dependence of the muon spin relaxation rate in
overdoped crystals displays an unusual behavior in the superconducting state. A
comparison to the results of NQR and lattice structure experiments on highly
doped samples provides compelling evidence for strong coupling of charge, spin
and structural inhomogeneities.Comment: 4 pages, 4 figures, new data, new figures and modified tex
Ground state and elementary excitations of single and binary Bose-Einstein condensates of trapped dipolar gases
We analyze the ground-state properties and the excitation spectrum of
Bose-Einstein condensates of trapped dipolar particles. First, we consider the
case of a single-component polarized dipolar gas. For this case we discuss the
influence of the trapping geometry on the stability of the condensate as well
as the effects of the dipole-dipole interaction on the excitation spectrum. We
discuss also the ground state and excitations of a gas composed of two
antiparallel dipolar components.Comment: 12 pages, 9 eps figures, final versio
Measurement of Mass and Width of the W Boson at LEP
We report on measurements of the mass and total decay width of the W boson
with the L3 detector at LEP. W-pair events produced in
interactions between 161 GeV and 183 GeV centre-of-mass energy are selected in
a data sample corresponding to a total luminosity of 76.7 pb. Combining
all final states in W-pair production, the mass and total decay width of the W
boson are determined to be GeV and
GeV, respectively
Search for Heavy Neutral and Charged Leptons in ee Annihilation at = 183 and 189 GeV
A search for unstable neutral and charged heavy leptons as well as for stable
charged heavy leptons is performed at center-of-mass energies = 183
and 189 GeV with the L3 detector at LEP. No evidence for their existence is
found. We exclude neutral heavy leptons which couple to the electron, muon or
tau family, of the Dirac type for masses below 92.4, 93.3 and 83.3 GeV, and of
the Majorana type for masses below 81.8, 84.1 and 73.5 GeV, respectively. We
exclude unstable charged heavy leptons for masses below 93.9 GeV for a wide
range of the associated neutral heavy lepton mass. If the unstable charged
heavy lepton decays to a light neutrino, we exclude masses below 92.4 GeV. The
production of stable charged heavy leptons with mass less than 93.5 GeV is also
excluded
Measurement of an Elongation of the Pion Source in Z Decays
We measure Bose-Einstein correlations between like-sign charged pion pairs in
hadronic Z decays with the L3 detector at LEP. The analysis is performed in
three dimensions in the longitudinal center-of-mass system. The pion source is
found to be elongated along the thrust axis with a ratio of transverse to
longitudinal radius of
Galaxy Clusters Associated with Short GRBs. II. Predictions for the Rate of Short GRBs in Field and Cluster Early-Type Galaxies
We determine the relative rates of short GRBs in cluster and field early-type
galaxies as a function of the age probability distribution of their
progenitors, P(\tau) \propto \tau^n. This analysis takes advantage of the
difference in the growth of stellar mass in clusters and in the field, which
arises from the combined effects of the galaxy stellar mass function, the
early-type fraction, and the dependence of star formation history on mass and
environment. This approach complements the use of the early- to late-type host
galaxy ratio, with the added benefit that the star formation histories of
early-type galaxies are simpler than those of late-type galaxies, and any
systematic differences between progenitors in early- and late-type galaxies are
removed. We find that the ratio varies from R(cluster)/R(field) ~ 0.5 for n =
-2 to ~ 3 for n = 2. Current observations indicate a ratio of about 2,
corresponding to n ~ 0 - 1. This is similar to the value inferred from the
ratio of short GRBs in early- and late-type hosts, but it differs from the
value of n ~ -1 for NS binaries in the Milky Way. We stress that this general
approach can be easily modified with improved knowledge of the effects of
environment and mass on the build-up of stellar mass, as well as the effect of
globular clusters on the short GRB rate. It can also be used to assess the age
distribution of Type Ia supernova progenitors.Comment: ApJ accepted versio
Search for leptophobic Z ' bosons decaying into four-lepton final states in proton-proton collisions at root s=8 TeV
Peer reviewe
- …