415 research outputs found
Entangling macroscopic diamonds at room temperature: Bounds on the continuous-spontaneous-localization parameters
A recent experiment [K. C. Lee et al., Science 334, 1253 (2011)] succeeded in
detecting entanglement between two macroscopic specks of diamonds, separated by
a macroscopic distance, at room temperature. This impressive results is a
further confirmation of the validity of quantum theory in (at least parts of)
the mesoscopic and macroscopic domain, and poses a challenge to collapse
models, which predict a violation of the quantum superposition principle, which
is the bigger the larger the system. We analyze the experiment in the light of
such models. We will show that the bounds placed by experimental data are
weaker than those coming from matter-wave interferometry and
non-interferometric tests of collapse models.Comment: 7 pages, 3 figures, v2: close to the published version, LaTe
Two- and four-quasiparticle states in the interacting boson model: Strong-coupling and decoupled band patterns in the SU(3) limit
An extension of the interacting boson approximation model is proposed by allowing for two- and four-quasiparticle excitations out of the boson space. The formation of band patterns based on two- and four-quasiparticle states is investigated in the SU(3) limit of the model. For hole-type (particle-type) fermions coupled to the SU(3) prolate (oblate) core, it is shown that the algebraic K-representation basis, which is the analog of the strong-coupling basis of the geometrical model, provides an appropriate description of the low-lying two-quasiparticle bands. In the case of particle-type (hole-type) fermions coupled to the SU(3) prolate (oblate) core, a new algebraic decoupling basis is derived that is equivalent in the geometrical limit to Stephens’ rotation-aligned basis. Comparing the wave functions that are obtained by diagonalization of the model Hamiltonian to the decoupling basis, several low-lying two-quasiparticle bands are identified. The effects of an interaction that conserves only the total nucleon number, mixing states with different number of fermions, are investigated in both the strong-coupling and decoupling limits. All calculations are performed for an SU(3) boson core and the h11/2 fermion orbital
Two-quasiparticle states in the interacting boson model. II. Electromagnetic properties in the SU(3) limit
The interacting boson approximation model, extended by allowing one boson to break and form a quasiparticle pair, is investigated in the SU(3) limit. Electromagnetic properties of yrast states are studied for the algebraic analogs of both the decoupling and strong-coupling limits. The effects of a pair-breaking interaction that mixes states with different numbers of quasiparticles are investigated for E2 transitions between yrast states. For the algebraic analog of the decoupling limit, it is shown that the mixing interaction has a strong influence on transitions in the region of crossing between the ground-state band and the lowest two-quasiparticle (2qp) band. The mixing interaction does not change the electromagnetic properties of the states of the ground-state band. This effect is due to the approximate cancellation between self-energy and vertex corrections, which corresponds to the nuclear Ward identity. For the algebraic analog of the strong-coupling limit, the K forbiddeness of E2 transitions between the ground-state band and the lowest 2qp band is high, and therefore the influence of the mixing interaction is negligible
CD4(+) and CD4(-) CD1D-restricted natural killer T cells in perinatally HIV-1 infected children receiving highly active antiretroviral therapy.
We conducted a cross-sectional study on 43 Italian perinatally human immunodeficiency virus-type 1 (HIV-1) infected children receiving highly active antiretroviral therapy (HAART) and 26 age-matched healthy controls to explore CD1d-restricted NKT subsets. CD4+CD1d-rectricted natural killer (NKT) cell depletion was evidenced in 26 HIV-1 infected children with active viral replication despite HAART. Conversely, no alteration was evidenced in 17 children with undetectable viral load, suggesting full recovery in both CD4+ and CD4− CDld-rectricted NKT cell subsets. The loss of CD4+ NKT cells in unresponsive children may have clinical consequences, including autoimmune disorders or cancer development. Future therapeutic perspectives are suggested
Optical detection and spectroscopic confirmation of supernova remnant G213.0-0.6 (now re-designated as G213.3-0.4)
During a detailed search for optical counterparts of known Galactic supernova
remnants (SNRs) using the Anglo Australian Observatory/United Kingdom Schmidt
Telescope (AAO/UKST) HAlpha survey of the southern Galactic plane we have found
characteristic optical HAlpha filaments and associated emission in the area of
SNR G213.0-0.6. Although this remnant was previously detected in the radio as a
non-thermal source, we also confirm emission at 4850 MHz in the Parkes-MIT-NRAO
(PMN) survey and at 1400 MHz in the NRAO/VLA Sky Survey (NVSS). There is an
excellent match in morphological structure between the optical (HAlpha) and
radio emission. We subsequently obtained optical spectroscopy of selected
HAlpha filaments using the South African Astronomical Observatory 1.9-m
telescope which confirmed shock excitation typical of supernova remnants. Our
discovery of HAlpha emission and the positional match with several radio
frequency maps led us to reassign G213.0-0.6 as G213.3-0.4 as these
co-ordinates more accurately reflect the actual centre of the SNR shell and
hence the most probable place of the original supernova explosion. Support for
this new SNR ID comes from the fact that the X-ray source 1RXS J065049.7-003220
is situated in the centre of this new remnant and could be connected with the
supernova explosion.Comment: 9 pages, 8 figures, Accepted for publishing in MNRA
Estimation of User's Orientation via Wearable UWB
User's orientation in indoor environments is an important part of her context. Orientation can be useful to understand what the user is looking at, and thus to improve the interaction between her and the surrounding environment. In this paper, we present a method based on wearable UWB-enabled devices. The position of the devices in space is used to estimate the user's orientation. We experimentally evaluated the impact of some operational parameters, such as the distance between worn devices, or some environmental conditions, such as the position of the user in the room. Results show that the accuracy of the method suits the needs of a wide range of practical purposes
Generalized seniority scheme in light Sn isotopes
The yrast generalized seniority states are compared with the corresponding
shell model states for the case of the Sn isotopes Sn. For most of
the cases the energies agree within 100 keV and the overlaps of the wave
functions are greater than 0.7.Comment: 8 pages, revtex. Submitted to Phys. Rev.
SS433's accretion disc, wind and jets: before, during and after a major flare
The Galactic microquasar SS433 occasionally exhibits a major flare when the
intensity of its emission increases significantly and rapidly. We present an
analysis of high-resolution, almost-nightly optical spectra obtained before,
during and after a major flare, whose complex emission lines are deconstructed
into single gaussians and demonstrate the different modes of mass loss in the
SS433 system. During our monitoring, an initial period of quiescence was
followed by increased activity which culminated in a radio flare. In the
transition period the accretion disc of SS433 became visible in H-alpha and HeI
emission lines and remained so until the observations were terminated; the
line-of-sight velocity of the centre of the disc lines during this time behaved
as though the binary orbit has significant eccentricity rather than being
circular, consistent with three recent lines of evidence. After the accretion
disc appeared its rotation speed increased steadily from 500 to 700 km/s. The
launch speed of the jets first decreased then suddenly increased. At the same
time as the jet launch speed increased, the wind from the accretion disc
doubled in speed. Two days afterwards, the radio flux exhibited a flare. These
data suggest that a massive ejection of material from the companion star loaded
the accretion disc and the system responded with mass loss via different modes
that together comprise the flare phenomena. We find that archival data reveal
similar behaviour, in that when the measured jet launch speed exceeds 0.29c
this is invariably simultaneous with, or a few days before, a radio flare. Thus
we surmise that a major flare consists of the overloading of the accretion
disc, resulting in the speeding up of the H-alpha rotation disc lines, followed
by enhanced mass loss not just via its famous jets at higher-than-usual speeds
but also directly from its accretion disc's wind.Comment: Accepted by MNRA
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