247,516 research outputs found
Finite-time Singularities in Swampland-related Dark Energy Models
In this work we shall investigate the singularity structure of the phase
space corresponding to an exponential quintessence dark energy model recently
related to swampland models. The dynamical system corresponding to the
cosmological system is an autonomous polynomial dynamical system, and by using
a mathematical theorem we shall investigate whether finite-time singularities
can occur in the dynamical system variables. As we demonstrate, the solutions
of the dynamical system are non-singular for all cosmic times and this result
is general, meaning that the initial conditions corresponding to the regular
solutions, belong to a general set of initial conditions and not to a limited
set of initial conditions. As we explain, a dynamical system singularity is not
directly related to a physical finite-time singularity. Then, by assuming that
the Hubble rate with functional form , is a
solution of the dynamical system, we investigate the implications of the
absence of finite-time singularities in the dynamical system variables. As we
demonstrate, Big Rip and a Type IV singularities can always occur if
respectively. However, Type II and Type III
singularities cannot occur in the cosmological system, if the Hubble rate we
quoted is considered a solution of the cosmological system.Comment: EPL Accepte
Machine Learning and Integrative Analysis of Biomedical Big Data.
Recent developments in high-throughput technologies have accelerated the accumulation of massive amounts of omics data from multiple sources: genome, epigenome, transcriptome, proteome, metabolome, etc. Traditionally, data from each source (e.g., genome) is analyzed in isolation using statistical and machine learning (ML) methods. Integrative analysis of multi-omics and clinical data is key to new biomedical discoveries and advancements in precision medicine. However, data integration poses new computational challenges as well as exacerbates the ones associated with single-omics studies. Specialized computational approaches are required to effectively and efficiently perform integrative analysis of biomedical data acquired from diverse modalities. In this review, we discuss state-of-the-art ML-based approaches for tackling five specific computational challenges associated with integrative analysis: curse of dimensionality, data heterogeneity, missing data, class imbalance and scalability issues
CMBPol Mission Concept Study: Probing Inflation with CMB Polarization
We summarize the utility of precise cosmic microwave background (CMB)
polarization measurements as probes of the physics of inflation. We focus on
the prospects for using CMB measurements to differentiate various inflationary
mechanisms. In particular, a detection of primordial B-mode polarization would
demonstrate that inflation occurred at a very high energy scale, and that the
inflaton traversed a super-Planckian distance in field space. We explain how
such a detection or constraint would illuminate aspects of physics at the
Planck scale. Moreover, CMB measurements can constrain the scale-dependence and
non-Gaussianity of the primordial fluctuations and limit the possibility of a
significant isocurvature contribution. Each such limit provides crucial
information on the underlying inflationary dynamics. Finally, we quantify these
considerations by presenting forecasts for the sensitivities of a future
satellite experiment to the inflationary parameters.Comment: 107 pages, 14 figures, 17 tables; Inflation Working Group
contribution to the CMBPol Mission Concept Study; v2: typos fixed and
references adde
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