131,338 research outputs found
MIROC4-ACTM: Model setup, input and output data for CH4 LETKF (Bisht et al., GMD-D, 2022)
No full textDetails in :
Bisht, J. S. H., Patra, P. K., Takigawa, M., Sekiya, T., Kanaya, Y., Saitoh, N., and Miyazaki, K.: Estimation of CH4 emission based on advanced 4D-LETKF assimilation system, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2022-719, 2022
On Solving Sparse Polynomial Factorization Related Problems
No full textIn a recent result of Bhargava, Saraf and Volkovich [FOCS’18; JACM’20], the first factor sparsity bound for constant individual degree polynomials was shown. In particular, it was shown that any factor of a polynomial with at most s terms and individual degree bounded by d can itself have at most s^O(d²log n) terms. It is conjectured, though, that the "true" sparsity bound should be polynomial (i.e. s^poly(d)). In this paper we provide supporting evidence for this conjecture by presenting polynomial-time algorithms for several problems that would be implied by a polynomial-size sparsity bound. In particular, we give efficient (deterministic) algorithms for identity testing of Σ^[2]ΠΣΠ^[ind-deg d] circuits and testing if a sparse polynomial is an exact power. Hence, our algorithms rely on different techniques
Derandomization via Symmetric Polytopes: Poly-Time Factorization of Certain Sparse Polynomials
No full textMore than three decades ago, after a series of results, Kaltofen and Trager (J. Symb. Comput. 1990) designed a randomized polynomial time algorithm for factorization of multivariate circuits. Derandomizing this algorithm, even for restricted circuit classes, is an important open problem. In particular, the case of s-sparse polynomials, having individual degree d = O(1), is very well-studied (Shpilka, Volkovich ICALP'10; Volkovich RANDOM'17; Bhargava, Saraf and Volkovich FOCS'18, JACM'20). We give a complete derandomization for this class assuming that the input is a symmetric polynomial over rationals. Generally, we prove an s^poly(d)-sparsity bound for the factors of symmetric polynomials over any field. This characterizes the known worst-case examples of sparsity blow-up for sparse polynomial factoring.
To factor f, we use techniques from convex geometry and exploit symmetry (only) in the Newton polytope of f. We prove a crucial result about convex polytopes, by introducing the concept of "low min-entropy", which might also be of independent interest
Introduction
No full textGrain legumes mainly consisting of common bean, pea, chickpea, faba bean, cowpea, lentil, pigeonpea, peanut, Asian Vigna species, grass pea and horsegram are under cultivation in a considerable area worldwide. With their higher protein content and symbiotic nitrogen-fixing bacteria in root nodules enabling them to fix their own nitrogen, reducing the fertilizer use in agriculture has become very important for the production systems. For most of these important grain legumes, a large number of germplasm accessions were characterized and evaluated for various agro-morphological traits, including biotic, abiotic and quality parameters. Core and mini-core collections have also been developed for the majority of grain legumes; they were further evaluated for different parameters. From these genetic resources, potential donors of desirable traits have been selected after evaluation and characterization and have been utilized in the genetic improvement of cultivars. Current available genomic resources and technologies can facilitate allele mining for novel traits of interest and incorporation from wild relatives into elite domestic genetic backgrounds
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Curating new ethnicities in a digital era: Women and media work in the British South Asian diaspora
No full textThis article analyses the unfolding impact of social media platforms on the politics of race, ethnicity, and gender in the UK. Revisiting Stuart Hall's foundational work on ‘new ethnicities’ and building on recent critiques of anti-racist struggles premised on mainstream media visibility and recognition, we explore how British South Asian women are navigating opportunities opened up by the digitalization of media industries. First, we examine how an interlocking set of shifts involving social media, techniques of self-making, and media industry logics has sparked the curation of ethnicities that challenge dominant ideas of Britishness and cultural citizenship. We then show that their success hinges on performing two forms of labour: crafting brand-ready representations that satisfy the media industries’ diversity mandates and, at the same time, subsuming their religious and ethnic identities into a picture of entrepreneurial womanhood that resonates with the logics of popular feminism
Astrometric and photometric study of NGC 6067, NGC 2506, and IC 4651 open clusters based on wide-field ground and Gaia DR2 data
No full textWe present an analysis of three southern open star clusters NGC 6067, NGC 2506, and IC 4651 using wide-field photometric and Gaia DR2 astrometric data. They are poorly studied clusters. We took advantage of the synergy between Gaia DR2 high precision astrometric measurements and ground-based wide-field photometry to isolate cluster members and further study these clusters. We identify the cluster members using proper motions, parallax and colour–magnitude diagrams. Mean proper motion of the clusters in μαcosδ and μδ is estimated as −1.90 ± 0.01 and −2.57 ± 0.01 mas yr−1 for NGC 6067, −2.57 ± 0.01, and 3.92 ± 0.01 mas yr−1 for NGC 2506 and −2.41 ± 0.01 and −5.05 ± 0.02 mas yr−1 for IC 4651. Distances are estimated as 3.01 ± 0.87, 3.88 ± 0.42, and 1.00 ± 0.08 kpc for the clusters NGC 6067, NGC 2506, and IC 4651, respectively, using parallaxes taken from Gaia DR2 catalogue. Galactic orbits are determined for these clusters using Galactic potential models. We find that these clusters have circular orbits. Cluster radii are determined as 10 arcmin for NGC 6067, 12 arcmin for NGC 2506, and 11 arcmin for IC 4651. Ages of the clusters estimated by isochrones fitting are 66 ± 8 Myr, 2.09 ± 0.14 Gyr, and 1.59 ± 0.14 Gyr for NGC 6067, NGC 2506, and IC 4651, respectively. Mass function slope for the entire region of cluster NGC 2506 is found to be comparable with the Salpeter value in the mass range of 0.77–1.54 M. The mass function analysis shows that the slope becomes flat when one goes from halo to core region in all the three clusters. A comparison of dynamical age with cluster’s age indicates that NGC 2506 and IC 4651 are dynamically relaxed clusters
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