1,349 research outputs found
An NIP-like Notion in Abstract Elementary Classes
This paper is a contribution to "neo-stability" type of result for abstract
elementary classes. Under certain set theoretic assumptions, we propose a
definition and a characterization of NIP in AECs. The class of AECs with NIP
properly contains the class of stable AECs. We show that for an AEC and
, is NIP if and only if there is a notion of
nonforking on it which we call a w*-good frame. On the other hand, the negation
of NIP leads to being able to encode subsets
Building models in small cardinals in local abstract elementary classes
There are many results in the literature where superstablity-like
independence notions, without any categoricity assumptions, have been used to
show the existence of larger models. In this paper we show that stability is
enough to construct larger models for small cardinals assuming a mild locality
condition for Galois types.
Suppose . Let be an
abstract elementary class with .
Assume has amalgamation in , no maximal model in
, and is stable in . If is -local, then has a model of cardinality .
The set theoretic assumption that and model theoretic
assumption of stability in can be weaken to the model theoretic
assumptions that for every and stability for -algebraic types in .
We further use the result just mentioned to provide a positive answer to
Grossberg's question for small cardinals assuming a mild locality condition for
Galois types and without any stability assumptions. This last result relies on
an unproven claim of Shelah (Fact 4.5 of this paper) which we were unable to
verify
Revealing the cosmic web dependent halo bias
Halo bias is the one of the key ingredients of the halo models. It was shown
at a given redshift to be only dependent, to the first order, on the halo mass.
In this study, four types of cosmic web environments: clusters, filaments,
sheets and voids are defined within a state of the art high resolution -body
simulation. Within those environments, we use both halo-dark matter
cross-correlation and halo-halo auto correlation functions to probe the
clustering properties of halos. The nature of the halo bias differs strongly
among the four different cosmic web environments we describe. With respect to
the overall population, halos in clusters have significantly lower biases in
the {} mass range. In other
environments however, halos show extremely enhanced biases up to a factor 10 in
voids for halos of mass {}. Such a strong
cosmic web environment dependence in the halo bias may play an important role
in future cosmological and galaxy formation studies. Within this cosmic web
framework, the age dependency of halo bias is found to be only significant in
clusters and filaments for relatively small halos \la 10^{12.5}\msunh.Comment: 14 pages, 14 figures, ApJ accepte
Omics analysis in Caenorhabditis elegans: pattern inference and interpretation
High-throughput molecular technologies have greatly enhanced our understanding of biological processes by characterizing expression changes of genes (microarray and RNA-Seq data) and proteins (proteomics data), or transcription factor targets and epigenetics states (ChIP-chip and ChIP-Seq data). Among them, transcriptome studies based on microarrays or RNA-Seq have the ability to identify genes involved in the response to environmental change or specific stressors, thereby helping us to infer the underlying biological processes.
During my PhD, I mainly focused on transcriptomic data analysis, using in most cases the nematode Caenorhabditis elegans as a model taxon. In particular, I have addressed seven specific projects: i) development of ABSSeq, an improved detection approach of differential gene expression for RNA-Seq data; ii) development of aFold, a method to fully moderate fold-change of RNA-Seq data and to improve gene ranking and visualization; iii) development of WormExp, a knowledge-based approach for interpreting gene sets in C. elegans; iv) exploration of the regulation of the C. elegans immune system using curated data sets from WormExp; v) characterization of putative major effectors (GATA transcription factors) in the C. elegans innate immune system; vi) comparison of the immune response of C. elegans at protein and transcript level.
In general, our work facilitates high-throughput data analysis via improving pattern inference and interpretation, which in practice provides new insights into the immune system of C. elegans
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