57,649 research outputs found
Imprint of DESI fiber assignment on the anisotropic power spectrum of emission line galaxies
The Dark Energy Spectroscopic Instrument (DESI), a multiplexed fiber-fed
spectrograph, is a Stage-IV ground-based dark energy experiment aiming to
measure redshifts for 29 million Emission-Line Galaxies (ELG), 4 million
Luminous Red Galaxies (LRG), and 2 million Quasi-Stellar Objects (QSO). The
survey design includes a pattern of tiling on the sky and the locations of the
fiber positioners in the focal plane of the telescope, with the observation
strategy determined by a fiber assignment algorithm that optimizes the
allocation of fibers to targets. This strategy allows a given region to be
covered on average five times for a five-year survey, but with coverage varying
between zero and twelve, which imprints a spatially-dependent pattern on the
galaxy clustering. We investigate the systematic effects of the fiber
assignment coverage on the anisotropic galaxy clustering of ELGs and show that,
in the absence of any corrections, it leads to discrepancies of order ten
percent on large scales for the power spectrum multipoles. We introduce a
method where objects in a random catalog are assigned a coverage, and the mean
density is separately computed for each coverage factor. We show that this
method reduces, but does not eliminate the effect. We next investigate the
angular dependence of the contaminated signal, arguing that it is mostly
localized to purely transverse modes. We demonstrate that the cleanest way to
remove the contaminating signal is to perform an analysis of the anisotropic
power spectrum and remove the lowest bin, leaving
modes accurate at the few-percent level. Here, is the cosine of the angle
between the line-of-sight and the direction of . We also investigate
two alternative definitions of the random catalog and show they are comparable
but less effective than the coverage randoms method.Comment: Submitted to JCA
Continuous formulations and analytical properties of the link transmission model
The link transmission model (LTM) has great potential for simulating traffic
flow in large-scale networks since it is much more efficient and accurate than
the Cell Transmission Model (CTM). However, there lack general continuous
formulations of LTM, and there has been no systematic study on its analytical
properties such as stationary states and stability of network traffic flow. In
this study we attempt to fill the gaps. First we apply the Hopf-Lax formula to
derive Newell's simplified kinematic wave model with given boundary cumulative
flows and the triangular fundamental diagram. We then apply the Hopf-Lax
formula to define link demand and supply functions, as well as link queue and
vacancy functions, and present two continuous formulations of LTM, by
incorporating boundary demands and supplies as well as invariant macroscopic
junction models. With continuous LTM, we define and solve the stationary states
in a road network. We also apply LTM to directly derive a Poincar\'e map to
analyze the stability of stationary states in a diverge-merge network. Finally
we present an example to show that LTM is not well-defined with non-invariant
junction models. We can see that Newell's model and LTM complement each other
and provide an alternative formulation of the network kinematic wave model.
This study paves the way for further extensions, analyses, and applications of
LTM in the future.Comment: 27 pages, 5 figure
Optimization of miRNA-seq data preprocessing.
The past two decades of microRNA (miRNA) research has solidified the role of these small non-coding RNAs as key regulators of many biological processes and promising biomarkers for disease. The concurrent development in high-throughput profiling technology has further advanced our understanding of the impact of their dysregulation on a global scale. Currently, next-generation sequencing is the platform of choice for the discovery and quantification of miRNAs. Despite this, there is no clear consensus on how the data should be preprocessed before conducting downstream analyses. Often overlooked, data preprocessing is an essential step in data analysis: the presence of unreliable features and noise can affect the conclusions drawn from downstream analyses. Using a spike-in dilution study, we evaluated the effects of several general-purpose aligners (BWA, Bowtie, Bowtie 2 and Novoalign), and normalization methods (counts-per-million, total count scaling, upper quartile scaling, Trimmed Mean of M, DESeq, linear regression, cyclic loess and quantile) with respect to the final miRNA count data distribution, variance, bias and accuracy of differential expression analysis. We make practical recommendations on the optimal preprocessing methods for the extraction and interpretation of miRNA count data from small RNA-sequencing experiments
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Design of an anti-inflammatory diet (ITIS diet) for patients with rheumatoid arthritis.
Background:Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease that affects synovial joints, leading to inflammation, joint destruction, loss of function, and disability. Although recent pharmaceutical advances have improved treatment of RA, patients with RA often inquire about dietary interventions to improve RA symptoms, as they perceive rapid changes in their symptoms after consumption of certain foods. There is evidence that some ingredients have pro- or anti-inflammatory effects. In addition, recent literature has shown a link between diet and microbiome changes. Both diet and the gut microbiome are linked to circulating metabolites that may modulate inflammation. However, evidence of the effects of an anti-inflammatory and probiotic-rich diet in patients with RA is scarce. There is also a need for biological data to support its anti-inflammatory effects. Methods:The main goal of this study is to delineate the design process for a diet tailored to our RA population. To achieve this goal, we collected information on diet, supplements, cooking methods, and intake of different ingredients for each patient. Different groups were interviewed, and their feedback was assessed to design a diet that incorporates suggested anti-inflammatory ingredients in a manner that was easy for patients to adopt based on their lifestyles and backgrounds. Results:We designed a diet that includes a high intake of potential anti-inflammatory ingredients. Feedback from highly motivated patients was critical in constructing an anti-inflammatory diet (ITIS diet) with elevated adherence. Conclusion:In order to tailor our diet, we surveyed our patients on several different parameters. We obtained important feedback on how feasible our ITIS diet is for RA patients. Using this feedback, we made minor improvements and finalized the design of the ITIS diet. This diet is being used in an on-going pilot study to determine their anti-inflammatory effect in pain and joint swelling in RA patients. Trial registration:Not applicable
Finite Boolean Algebras for Solid Geometry using Julia's Sparse Arrays
The goal of this paper is to introduce a new method in computer-aided
geometry of solid modeling. We put forth a novel algebraic technique to
evaluate any variadic expression between polyhedral d-solids (d = 2, 3) with
regularized operators of union, intersection, and difference, i.e., any CSG
tree. The result is obtained in three steps: first, by computing an independent
set of generators for the d-space partition induced by the input; then, by
reducing the solid expression to an equivalent logical formula between Boolean
terms made by zeros and ones; and, finally, by evaluating this expression using
bitwise operators. This method is implemented in Julia using sparse arrays. The
computational evaluation of every possible solid expression, usually denoted as
CSG (Constructive Solid Geometry), is reduced to an equivalent logical
expression of a finite set algebra over the cells of a space partition, and
solved by native bitwise operators.Comment: revised version submitted to Computer-Aided Geometric Desig
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