8,230 research outputs found
Longitudinal Atomic Beam Spin Echo Experiments: A possible way to study Parity Violation in Hydrogen
We discuss the propagation of hydrogen atoms in static electric and magnetic
fields in a longitudinal atomic beam spin echo (lABSE) apparatus. Depending on
the choice of the external fields the atoms may acquire both dynamical and
geometrical quantum mechanical phases. As an example of the former, we show
first in-beam spin rotation measurements on atomic hydrogen, which are in
excellent agreement with theory. Additional calculations of the behaviour of
the metastable 2S states of hydrogen reveal that the geometrical phases may
exhibit the signature of parity-(P-)violation. This invites for possible future
lABSE experiments, focusing on P-violating geometrical phases in the lightest
of all atoms.Comment: 6 pages, 4 figure
ARIA 2016 : Care pathways implementing emerging technologies for predictive medicine in rhinitis and asthma across the life cycle
European Innovation Partnership on Active and Healthy Ageing Reference Site MACVIA-France, EU Structural and Development Fund Languedoc-Roussillon, ARIA.Peer reviewedPublisher PD
Geodiversidade e viticultura: identidade regional e terroir vitivinĂcola no Estado do Rio Grande do Sul, Brasil.
O Rio Grande do Sul(RS) tem uma geodiversidade que induzĂ formação de solos e terrenos, incluindo os fatores naturais e culturais que implicam respostas agronĂŽmicas diferentes pela videira. Estas caracterĂsticas valorizam a produção de vinhos com qualidades Ășnicas, que podem definir diferentes terroirs.Resumo
The Physical Role of Gravitational and Gauge Degrees of Freedom in General Relativity - II: Dirac versus Bergmann observables and the Objectivity of Space-Time
(abridged)The achievements of the present work include: a) A clarification of
the multiple definition given by Bergmann of the concept of {\it (Bergmann)
observable. This clarification leads to the proposal of a {\it main conjecture}
asserting the existence of i) special Dirac's observables which are also
Bergmann's observables, ii) gauge variables that are coordinate independent
(namely they behave like the tetradic scalar fields of the Newman-Penrose
formalism). b) The analysis of the so-called {\it Hole} phenomenology in strict
connection with the Hamiltonian treatment of the initial value problem in
metric gravity for the class of Christoudoulou -Klainermann space-times, in
which the temporal evolution is ruled by the {\it weak} ADM energy. It is
crucial the re-interpretation of {\it active} diffeomorphisms as {\it passive
and metric-dependent} dynamical symmetries of Einstein's equations, a
re-interpretation which enables to disclose their (nearly unknown) connection
to gauge transformations on-shell; this is expounded in the first paper
(gr-qc/0403081). The use of the Bergmann-Komar {\it intrinsic
pseudo-coordinates} allows to construct a {\it physical atlas} of 4-coordinate
systems for the 4-dimensional {\it mathematical} manifold, in terms of the
highly non-local degrees of freedom of the gravitational field (its four
independent {\it Dirac observables}), and to realize the {\it physical
individuation} of the points of space-time as {\it point-events} as a
gauge-fixing problem, also associating a non-commutative structure to each
4-coordinate system.Comment: 41 pages, Revtex
On the Transit Potential of the Planet Orbiting iota Draconis
Most of the known transiting exoplanets are in short-period orbits, largely
due to the bias inherent in detecting planets through the transit technique.
However, the eccentricity distribution of the known radial velocity planets
results in many of those planets having a non-negligible transit probability.
One such case is the massive planet orbiting the giant star iota Draconis, a
situation where both the orientation of the planet's eccentric orbit and the
size of the host star inflate the transit probability to a much higher value
than for a typical hot Jupiter. Here we present a revised fit of the radial
velocity data with new measurements and a photometric analysis of the stellar
variability. We provide a revised transit probability, an improved transit
ephemeris, and discuss the prospects for observing a transit of this planet
from both the ground and space.Comment: 6 pages, 7 figures, accepted for publication in ApJ. Radial
velocities will be made available in the on-line version and through the NASA
Star and Exoplanet Database (NStED). Minor corrections from ApJ proof have
been applie
The Fundamental Plane in RX J0142.0+2131: a galaxy cluster merger at z=0.28
We present the Fundamental Plane (FP) in the z = 0.28 cluster of galaxies RX
J0142.0+2131. There is no evidence for a difference in the slope of the FP when
compared with the Coma cluster, although the internal scatter is larger. On
average, stellar populations in RX J0142.0+2131 have rest-frame V-band
mass-to-light ratios (M/L_V) 0.29+-0.03 dex lower than in Coma. This is
significantly lower than expected for a passively-evolving cluster formed at
z_f=2. Lenticular galaxies have lower average M/L_V and a distribution of M/L_V
with larger scatter than ellipticals. Lower mass-to-light ratios are not due to
recent star formation: our previous spectroscopic observations of RX
J0142.0+2131 E/S0 galaxies showed no evidence for significant star-formation
within the past ~4 Gyr. However, cluster members have enhanced alpha-element
abundance ratios, which may act to decrease M/L_V. The increased scatter in the
RX J0142.0+2131 FP reflects a large scatter in M/L_V implying that galaxies
have undergone bursts of star formation over a range of epochs. The seven
easternmost cluster galaxies, including the second brightest member, have M/L_V
consistent with passive evolution and z_f = 2. We speculate that RX
J0142.0+2131 is a cluster-cluster merger where the galaxies to the east are yet
to fall into the main cluster body or have not experienced star formation as a
result of the merger.Comment: 4 pages, 2 figures, accepted for publication in ApJ Letter
Non-continuous Froude number scaling for the closure depth of a cylindrical cavity
A long, smooth cylinder is dragged through a water surface to create a cavity
with an initially cylindrical shape. This surface void then collapses due to
the hydrostatic pressure, leading to a rapid and axisymmetric pinch-off in a
single point. Surprisingly, the depth at which this pinch-off takes place does
not follow the expected Froude power-law. Instead, it displays two
distinct scaling regimes separated by discrete jumps, both in experiment and in
numerical simulations (employing a boundary integral code). We quantitatively
explain the above behavior as a capillary waves effect. These waves are created
when the top of the cylinder passes the water surface. Our work thus gives
further evidence for the non-universality of the void collapse
Oscillations of the magnetic polarization in a Kondo impurity at finite magnetic fields
The electronic properties of a Kondo impurity are investigated in a magnetic
field using linear response theory. The distribution of electrical charge and
magnetic polarization are calculated in real space. The (small) magnetic field
does not change the charge distribution. However, it unmasks the Kondo cloud.
The (equal) weight of the d-electron components with their magnetic moment up
and down is shifted and the compensating s-electron clouds don't cancel any
longer (a requirement for an experimental detection of the Kondo cloud). In
addition to the net magnetic polarization of the conduction electrons an
oscillating magnetic polarization with a period of half the Fermi wave length
is observed. However, this oscillating magnetic polarization does not show the
long range behavior of Rudermann-Kittel-Kasuya-Yosida oscillations because the
oscillations don't extend beyond the Kondo radius. They represent an internal
electronic structure of the Kondo impurity in a magnetic field. PACS: 75.20.Hr,
71.23.An, 71.27.+
Quantization of a relativistic particle on the SL(2,R) manifold based on Hamiltonian reduction
A quantum theory is constructed for the system of a relativistic particle
with mass m moving freely on the SL(2,R) group manifold. Applied to the
cotangent bundle of SL(2,R), the method of Hamiltonian reduction allows us to
split the reduced system into two coadjoint orbits of the group. We find that
the Hilbert space consists of states given by the discrete series of the
unitary irreducible representations of SL(2,R), and with a positive-definite,
discrete spectrum.Comment: 12 pages, INS-Rep.-104
Near-infrared and X-ray obscuration to the nucleus of the Seyfert 2 galaxy NGC 3281
We present the results of a near-infrared and X-ray study of the Seyfert 2
galaxy NGC 3281. Emission from the Seyfert nucleus is detected in both regions
of the electromagnetic spectrum, allowing us to infer both the equivalent line
of sight hydrogen column density, N_H = 71.0(+11.3,-12.3)e26/m^2 and the
extinction due to dust, A_V = 22+/-11 magnitudes (90% confidence intervals). We
infer a ratio of N_H/A_V which is an order of magnitude larger than that
determined along lines of sight in the Milky Way and discuss possible
interpretations. We consider the most plausible explanation to be a dense cloud
in the foreground of both the X-ray and infrared emitting regions which
obscures the entire X-ray source but only a fraction of the much larger
infrared source.Comment: 23 pages including 9 figure
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