80 research outputs found
Pattern Count on Multiply Restricted Permutations
Previous work has studied the pattern count on singly restricted
permutations. In this work, we focus on patterns of length 3 in multiply
restricted permutations, especially for double and triple pattern-avoiding
permutations. We derive explicit formulae or generating functions for various
occurrences of length 3 patterns on multiply restricted permutations, as well
as some combinatorial interpretations for non-trivial pattern relationships.Comment: 23 pages, 2 figure
Mixed Statistics on 01-Fillings of Moon Polyominoes
We establish a stronger symmetry between the numbers of northeast and
southeast chains in the context of 01-fillings of moon polyominoes. Let \M be
a moon polyomino with rows and columns. Consider all the 01-fillings of
\M in which every row has at most one 1. We introduce four mixed statistics
with respect to a bipartition of rows or columns of \M. More precisely, let
and be the union of rows whose
indices are in . For any filling , the top-mixed (resp. bottom-mixed)
statistic (resp. ) is the sum of the number of
northeast chains whose top (resp. bottom) cell is in , together
with the number of southeast chains whose top (resp. bottom) cell is in the
complement of . Similarly, we define the left-mixed and
right-mixed statistics and , where is a subset
of the column index set . Let be any of these
four statistics , , and , we show that the joint distribution of the pair is symmetric and independent of the subsets . In
particular, the pair of statistics is
equidistributed with (\se(M),\ne(M)), where \se(M) and are the
numbers of southeast chains and northeast chains of , respectively.Comment: 20 pages, 6 figure
Comparison of evolutionary algorithms in gene regulatory network model inference
Background: The evolution of high throughput technologies that measure gene expression levels has created a
data base for inferring GRNs (a process also known as reverse engineering of GRNs). However, the nature of
these data has made this process very di±cult. At the moment, several methods of discovering qualitative
causal relationships between genes with high accuracy from microarray data exist, but large scale quantitative
analysis on real biological datasets cannot be performed, to date, as existing approaches are not suitable for real
microarray data which are noisy and insu±cient.
Results: This paper performs an analysis of several existing evolutionary algorithms for quantitative gene
regulatory network modelling. The aim is to present the techniques used and oÂźer a comprehensive comparison
of approaches, under a common framework. Algorithms are applied to both synthetic and real gene expression
data from DNA microarrays, and ability to reproduce biological behaviour, scalability and robustness to noise are assessed and compared.
Conclusions: Presented is a comparison framework for assessment of evolutionary algorithms, used to infer gene
regulatory networks. Promising methods are identiÂŻed and a platform for development of appropriate model
formalisms is established
Guanosine effect on cholesterol efflux and apolipoprotein E expression in astrocytes
The main source of cholesterol in the central nervous system (CNS) is represented by glial cells, mainly astrocytes, which also synthesise and secrete apolipoproteins, in particular apolipoprotein E (ApoE), the major apolipoprotein in the brain, thus generating cholesterol-rich high density lipoproteins (HDLs). This cholesterol trafficking, even though still poorly known, is considered to play a key role in different aspects of neuronal plasticity and in the stabilisation of synaptic transmission. Moreover, cell cholesterol depletion has recently been linked to a reduction in amyloid beta formation. Here we demonstrate that guanosine, which we previously reported to exert several neuroprotective effects, was able to increase cholesterol efflux from astrocytes and C6 rat glioma cells in the absence of exogenously added acceptors. In this effect the phosphoinositide 3 kinase/extracellular signal-regulated kinase 1/2 (PI3K/ERK1/2) pathway seems to play a pivotal role. Guanosine was also able to increase the expression of ApoE in astrocytes, whereas it did not modify the levels of ATP-binding cassette protein A1 (ABCA1), considered the main cholesterol transporter in the CNS. Given the emerging role of cholesterol balance in neuronal repair, these effects provide evidence for a role of guanosine as a potential pharmacological tool in the modulation of cholesterol homeostasis in the brain
Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median ). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July
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