659,079 research outputs found
Probing the neutrino mass hierarchy with CMB weak lensing
We forecast constraints on cosmological parameters with primary CMB
anisotropy information and weak lensing reconstruction with a future
post-Planck CMB experiment, the Cosmic Origins Explorer (COrE), using
oscillation data on the neutrino mass splittings as prior information. Our MCMC
simulations in flat models with a non-evolving equation-of-state of dark energy
w give typical 68% upper bounds on the total neutrino mass of 0.136 eV and
0.098 eV for the inverted and normal hierarchies respectively, assuming the
total summed mass is close to the minimum allowed by the oscillation data for
the respective hierarchies (0.10 eV and 0.06 eV). Including information from
future baryon acoustic oscillation measurements with the complete BOSS, Type 1a
supernovae distance moduli from WFIRST, and a realistic prior on the Hubble
constant, these upper limits shrink to 0.118 eV and 0.080 eV for the inverted
and normal hierarchies, respectively. Addition of these distance priors also
yields percent-level constraints on w. We find tension between our MCMC results
and the results of a Fisher matrix analysis, most likely due to a strong
geometric degeneracy between the total neutrino mass, the Hubble constant, and
w in the unlensed CMB power spectra. If the minimal-mass, normal hierarchy were
realised in nature, the inverted hierarchy should be disfavoured by the full
data combination at typically greater than the 2-sigma level. For the
minimal-mass inverted hierarchy, we compute the Bayes' factor between the two
hierarchies for various combinations of our forecast datasets, and find that
the future probes considered here should be able to provide `strong' evidence
(odds ratio 12:1) for the inverted hierarchy. Finally, we consider potential
biases of the other cosmological parameters from assuming the wrong hierarchy
and find that all biases on the parameters are below their 1-sigma marginalised
errors.Comment: 16 pages, 13 figures; minor changes to match the published version,
references adde
Hierarchical Quantized Representations for Script Generation
Scripts define knowledge about how everyday scenarios (such as going to a
restaurant) are expected to unfold. One of the challenges to learning scripts
is the hierarchical nature of the knowledge. For example, a suspect arrested
might plead innocent or guilty, and a very different track of events is then
expected to happen. To capture this type of information, we propose an
autoencoder model with a latent space defined by a hierarchy of categorical
variables. We utilize a recently proposed vector quantization based approach,
which allows continuous embeddings to be associated with each latent variable
value. This permits the decoder to softly decide what portions of the latent
hierarchy to condition on by attending over the value embeddings for a given
setting. Our model effectively encodes and generates scripts, outperforming a
recent language modeling-based method on several standard tasks, and allowing
the autoencoder model to achieve substantially lower perplexity scores compared
to the previous language modeling-based method.Comment: EMNLP 201
Perceptual considerations for quality of service management: An integrated architecture
The official published version can be obtained from the link below - copyright @ 2001 SpringerIn this paper, we suggest an integrated architecture that makes use of the objective-technical information provided by the designer and the subjectiveperceptual information supplied by the user for intelligent decision making in the construction of communication protocols. Thus, this approach, based on the Analytic Hierarchy Process, incorporates not only classical Quality of Service (QoS) considerations, but, indeed, user preferences as well. Furthermore, in keeping with the task-dependent nature consistently identified in multimedia scenarios, the suggested communication protocols also take into account the type of multimedia application, which they are transporting. Lastly, our approach also opens the possibility for such protocols to dynamically adapt based on a changing operating environment
Concepts of quantum non-Markovianity: a hierarchy
Markovian approximation is a widely-employed idea in descriptions of the
dynamics of open quantum systems (OQSs). Although it is usually claimed to be a
concept inspired by classical Markovianity, the term quantum Markovianity is
used inconsistently and often unrigorously in the literature. In this report we
compare the descriptions of classical stochastic processes and quantum
stochastic processes (as arising in OQSs), and show that there are inherent
differences that lead to the non-trivial problem of characterizing quantum
non-Markovianity. Rather than proposing a single definition of quantum
Markovianity, we study a host of Markov-related concepts in the quantum regime.
Some of these concepts have long been used in quantum theory, such as quantum
white noise, factorization approximation, divisibility, Lindblad master
equation, etc.. Others are first proposed in this report, including those we
call past-future independence, no (quantum) information backflow, and
composability. All of these concepts are defined under a unified framework,
which allows us to rigorously build hierarchy relations among them. With
various examples, we argue that the current most often used definitions of
quantum Markovianity in the literature do not fully capture the memoryless
property of OQSs. In fact, quantum non-Markovianity is highly
context-dependent. The results in this report, summarized as a hierarchy
figure, bring clarity to the nature of quantum non-Markovianity.Comment: Clarifications and references added; discussion of the related
classical hierarchy significantly improved. To appear in Physics Report
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