3,213 research outputs found
The Renormalizable Three-Term Polynomial Inflation with Large Tensor-to-Scalar Ratio
We systematically study the renormalizable three-term polynomial inflation in
the supersymmetric and non-supersymmetric models. The supersymmetric inflaton
potentials can be realized in supergravity theory, and only have two
independent parameters. We show that the general renormalizable supergravity
model is equivalent to one kind of our supersymmetric models. We find that the
spectral index and tensor-to-scalar ratio can be consistent with the Planck and
BICEP2 results, but the running of spectral index is always out of the
range. If we do not consider the BICEP2 experiment, these
inflationary models can be highly consistent with the Planck observations and
saturate its upper bound on the tensor-to-scalar ratio (). Thus,
our models can be tested at the future Planck and QUBIC experiments.Comment: 38 pages, 40 figure
The Supersymmetric Standard Models with a Pseudo-Dirac Gluino from Hybrid and Term Supersymmetry Breakings
We propose the Supersymmetric Standard Models (SSMs) with a pseudo-Dirac
gluino from hybrid and term supersymmetry (SUSY) breakings. Similar to
the SSMs before the LHC, all the supersymmetric particles in the Minimal SSM
(MSSM) obtain the SUSY breaking soft terms from the traditional gravity
mediation and have masses within about 1 TeV except gluino. To evade the LHC
SUSY search constraints, the gluino also has a heavy Dirac mass above 3 TeV
from term SUSY breaking. Interestingly, such a heavy Dirac gluino mass will
not induce the electroweak fine-tuning problem. We realize such SUSY breakings
via an anomalous gauge symmetry inspired from string models. To
maintain the gauge coupling unification and increase the Higgs boson mass, we
introduce extra vector-like particles. We study the viable parameter space
which satisfies all the current experimental constraints, and present a
concrete benchmark point. This kind of models not only preserves the merits of
pre-LHC SSMs such as naturalness, dark matter, etc, but also solves the
possible problems in the SSMs with Dirac gauginos due to the -term gravity
mediation.Comment: 6 pages,3 figures,revised versio
On the anisotropies of the cosmological gravitational-wave background from pulsar timing array observations
Significant evidence for a stochastic gravitational-wave background has
recently been reported by several Pulsar Timing Array observations. These
studies have shown that, in addition to astrophysical explanations based on
supermassive black hole binaries (SMBHBs), cosmological origins are considered
equally important sources for these signals. To further explore these
cosmological sources, in this study, we discuss the anisotropies in the
cosmological gravitational wave background (CGWB) in a model-independent way.
Taking the North American Nanohertz Observatory for Gravitational Waves
(NANOGrav) 15-year dataset as a benchmark, we estimate the angular power
spectra of the CGWB and their cross-correlations with cosmic microwave
background (CMB) fluctuations and weak gravitational lensing. We find that the
NANOGrav 15-year data implies suppressed Sachs-Wolf (SW) effects in the CGBW
spectrum, leading to a marginally negative cross-correlation with the CMB at
large scales. This procedure is applicable to signals introduced by different
early universe processes and is potentially useful for identifying unique
features about anisotropies of CGWB from future space-based interferometers and
astrometric measurements.Comment: 22 pages, 4 figure
Feature Selection for Longitudinal Data by Using Sign Averages to Summarize Gene Expression Values over Time
With the rapid evolution of high-throughput technologies, time series/longitudinal high-throughput experiments have become possible and affordable. However, the development of statistical methods dealing with gene expression profiles across time points has not kept up with the explosion of such data. The feature selection process is of critical importance for longitudinal microarray data. In this study, we proposed aggregating a gene’s expression values across time into a single value using the sign average method, thereby degrading a longitudinal feature selection process into a classic one. Regularized logistic regression models with pseudogenes (i.e., the sign average of genes across time as predictors) were then optimized by either the coordinate descent method or the threshold gradient descent regularization method. By applying the proposed methods to simulated data and a traumatic injury dataset, we have demonstrated that the proposed methods, especially for the combination of sign average and threshold gradient descent regularization, outperform other competitive algorithms. To conclude, the proposed methods are highly recommended for studies with the objective of carrying out feature selection for longitudinal gene expression data
An Ensemble of the iCluster Method to Analyze Longitudinal lncRNA Expression Data for Psoriasis Patients
BACKGROUND: Psoriasis is an immune-mediated, inflammatory disorder of the skin with chronic inflammation and hyper-proliferation of the epidermis. Since psoriasis has genetic components and the diseased tissue of psoriasis is very easily accessible, it is natural to use high-throughput technologies to characterize psoriasis and thus seek targeted therapies. Transcriptional profiles change correspondingly after an intervention. Unlike cross-sectional gene expression data, longitudinal gene expression data can capture the dynamic changes and thus facilitate causal inference.
METHODS: Using the iCluster method as a building block, an ensemble method was proposed and applied to a longitudinal gene expression dataset for psoriasis, with the objective of identifying key lncRNAs that can discriminate the responders from the non-responders to two immune treatments of psoriasis.
RESULTS: Using support vector machine models, the leave-one-out predictive accuracy of the 20-lncRNA signature identified by this ensemble was estimated as 80%, which outperforms several competing methods. Furthermore, pathway enrichment analysis was performed on the target mRNAs of the identified lncRNAs. Of the enriched GO terms or KEGG pathways, proteasome, and protein deubiquitination is included. The ubiquitination-proteasome system is regarded as a key player in psoriasis, and a proteasome inhibitor to target ubiquitination pathway holds promises for treating psoriasis.
CONCLUSIONS: An integrative method such as iCluster for multiple data integration can be adopted directly to analyze longitudinal gene expression data, which offers more promising options for longitudinal big data analysis. A comprehensive evaluation and validation of the resulting 20-lncRNA signature is highly desirable
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