4,772 research outputs found
R\'enyi generalizations of quantum information measures
Quantum information measures such as the entropy and the mutual information
find applications in physics, e.g., as correlation measures. Generalizing such
measures based on the R\'enyi entropies is expected to enhance their scope in
applications. We prescribe R\'enyi generalizations for any quantum information
measure which consists of a linear combination of von Neumann entropies with
coefficients chosen from the set {-1,0,1}. As examples, we describe R\'enyi
generalizations of the conditional quantum mutual information, some quantum
multipartite information measures, and the topological entanglement entropy.
Among these, we discuss the various properties of the R\'enyi conditional
quantum mutual information and sketch some potential applications. We
conjecture that the proposed R\'enyi conditional quantum mutual informations
are monotone increasing in the R\'enyi parameter, and we have proofs of this
conjecture for some special cases.Comment: 9 pages, related to and extends the results from arXiv:1403.610
The effects of upcoding, cream skimming and readmissions on the Italian hospitals efficiency: a populationābased investigation
In this paper we analyze the effects of some distortions induced by prospective payment system, i.e. Upcoding, Cream Skimming and Readmissions, on hospitalsā technical efficiency. We estimate a production function using a populationābased dataset composed by all active hospitals in an Italian region during the period 1998ā2007. We show that cream skimming and upcoding have a negative impact on hospitalsā technical efficiency, while readmissions have a positive effect. Moreover, we find that private hospitals are more engaged in cream skimming than public and notāforāprofit ones, while we observe no ownership differences regarding upcoding. Notāforāprofit hospitals have the highest readmission index. Last, notāforāprofit and public hospitals have the same efficiency levels, while private hospitals have the lowest technical efficiency.Upcoding, Cream Skimming, Readmission, Hospital Technical Efficiency, Ownership.
Simultaneous Multiwavelength Observations of Magnetic Activity in Ultracool Dwarfs. IV. The Active, Young Binary NLTT 33370 AB (=2MASS J13142039+1320011)
We present multi-epoch simultaneous radio, optical, H{\alpha}, UV, and X-ray
observations of the active, young, low-mass binary NLTT 33370 AB (blended
spectral type M7e). This system is remarkable for its extreme levels of
magnetic activity: it is the most radio-luminous ultracool dwarf (UCD) known,
and here we show that it is also one of the most X-ray luminous UCDs known. We
detect the system in all bands and find a complex phenomenology of both flaring
and periodic variability. Analysis of the optical light curve reveals the
simultaneous presence of two periodicities, 3.7859 0.0001 and 3.7130
0.0002 hr. While these differ by only ~2%, studies of differential
rotation in the UCD regime suggest that it cannot be responsible for the two
signals. The system's radio emission consists of at least three components:
rapid 100% polarized flares, bright emission modulating periodically in phase
with the optical emission, and an additional periodic component that appears
only in the 2013 observational campaign. We interpret the last of these as a
gyrosynchrotron feature associated with large-scale magnetic fields and a cool,
equatorial plasma torus. However, the persistent rapid flares at all rotational
phases imply that small-scale magnetic loops are also present and reconnect
nearly continuously. We present an SED of the blended system spanning more than
9 orders of magnitude in wavelength. The significant magnetism present in NLTT
33370 AB will affect its fundamental parameters, with the components' radii and
temperatures potentially altered by ~+20% and ~-10%, respectively. Finally, we
suggest spatially resolved observations that could clarify many aspects of this
system's nature.Comment: emulateapj, 22 pages, 15 figures, ApJ in press; v2: fixes low-impact
error in Figure 15; v3: now in-pres
The effect of dispersoids and processing variables on grain refinement of aluminium alloys deformed by ECAE
Star formation properties of sub-mJy radio sources
We investigate the star formation properties of ~800 sources detected in one
of the deepest radio surveys at 1.4 GHz. Our sample spans a wide redshift range
(~0.1 - 4) and about four orders of magnitude in star formation rate (SFR). It
includes both star forming galaxies (SFGs) and active galactic nuclei (AGNs),
further divided into radio-quiet and radio-loud objects. We compare the SFR
derived from the far infrared luminosity, as traced by Herschel, with the SFR
computed from their radio emission. We find that the radio power is a good SFR
tracer not only for pure SFGs but also in the host galaxies of RQ AGNs, with no
significant deviation with redshift or specific SFR. Moreover, we quantify the
contribution of the starburst activity in the SFGs population and the
occurrence of AGNs in sources with different level of star formation. Finally
we discuss the possibility of using deep radio survey as a tool to study the
cosmic star formation history.Comment: 18 pages, 14 figures, 1 table (available in its entirety as ancillary
data
The effect of dispersoids on the grain refinement mechanisms during deformation of aluminium alloys to ultra-high strains
Renyi generalizations of the conditional quantum mutual information
The conditional quantum mutual information of a tripartite state
is an information quantity which lies at the center of many
problems in quantum information theory. Three of its main properties are that
it is non-negative for any tripartite state, that it decreases under local
operations applied to systems and , and that it obeys the duality
relation for a four-party pure state on systems . The
conditional mutual information also underlies the squashed entanglement, an
entanglement measure that satisfies all of the axioms desired for an
entanglement measure. As such, it has been an open question to find R\'enyi
generalizations of the conditional mutual information, that would allow for a
deeper understanding of the original quantity and find applications beyond the
traditional memoryless setting of quantum information theory. The present paper
addresses this question, by defining different -R\'enyi generalizations
of the conditional mutual information, some of which we can
prove converge to the conditional mutual information in the limit
. Furthermore, we prove that many of these generalizations
satisfy non-negativity, duality, and monotonicity with respect to local
operations on one of the systems or (with it being left as an open
question to prove that monotoniticity holds with respect to local operations on
both systems). The quantities defined here should find applications in quantum
information theory and perhaps even in other areas of physics, but we leave
this for future work. We also state a conjecture regarding the monotonicity of
the R\'enyi conditional mutual informations defined here with respect to the
R\'enyi parameter . We prove that this conjecture is true in some
special cases and when is in a neighborhood of one.Comment: v6: 53 pages, final published versio
- ā¦