324,997 research outputs found
Learning Generalized Depth Three Arithmetic Circuits in the Non-Degenerate Case
No full textConsider a homogeneous degree d polynomial f = T₁ + ⋯ + T_s, T_i = g_i(_{i,1}, …, _{i, m}) where g_i’s are homogeneous m-variate degree d polynomials and _{i,j}’s are linear polynomials in n variables. We design a (randomized) learning algorithm that given black-box access to f, computes black-boxes for the T_i’s. The running time of the algorithm is poly(n, m, d, s) and the algorithm works under some non-degeneracy conditions on the linear forms and the g_i’s, and some additional technical assumptions n ≥ (md)², s ≤ n^{d/4}. The non-degeneracy conditions on _{i,j}’s constitute non-membership in a variety, and hence are satisfied when the coefficients of _{i,j}’s are chosen uniformly and randomly from a large enough set. The conditions on g_i’s are satisfied for random polynomials and also for natural polynomials common in the study of arithmetic complexity like determinant, permanent, elementary symmetric polynomial, iterated matrix multiplication. A particularly appealing algorithmic corollary is the following: Given black-box access to an f = Det_r(L^(1)) + … + Det_r(L^(s)), where L^(k) = (_{i,j}^(k))_{i,j} with _{i,j}^(k)’s being linear forms in n variables chosen randomly, there is an algorithm which in time poly(n, r) outputs matrices (M^(k))_k of linear forms s.t. there exists a permutation π: [s] → [s] with Det_r(M^(k)) = Det_r(L^(π(k))).
Our work follows the works [Neeraj Kayal and Chandan Saha, 2019; Garg et al., 2020] which use lower bound methods in arithmetic complexity to design average case learning algorithms. It also vastly generalizes the result in [Neeraj Kayal and Chandan Saha, 2019] about learning depth three circuits, which is a special case where each g_i is just a monomial. At the core of our algorithm is the partial derivative method which can be used to prove lower bounds for generalized depth three circuits. To apply the general framework in [Neeraj Kayal and Chandan Saha, 2019; Garg et al., 2020], we need to establish that the non-degeneracy conditions arising out of applying the framework with the partial derivative method are satisfied in the random case. We develop simple but general and powerful tools to establish this, which might be useful in designing average case learning algorithms for other arithmetic circuit models
Resurrecting tilak chandan: the fall and future rise of local rice varieties in North India
No full textKhichdi is a simple dish prepared in the north Indian city of Rampur in the Rohilkhand region of Uttar Pradesh by cooking rice with urad dal and spices. With historical and cultural significance, it remains staple to the winter diet of all social strata. Since the 1980s, however, the rice variety previously used, tilak chandan, has experienced near-extinction in the face of growing dependence on hybrid varieties. The disappearance of this local rice reflects broader trends in agro-biodiversity associated with the Green Revolution compounded by global climate change. This paper explores these eco-cultural tensions by charting the efforts of an interdisciplinary and international collaboration bringing together historians, plant scientists and farmers to resurrect tilak chandan and other traditional varieties in the Rampur rice belt. Field trials at Benazir Farm in Rampur (2020-22) revealed the challenges of cultivating local heritage varieties, including: (i) recovery of seeds; (ii) longer growing cycles, meaning higher exposure to pests and fungal infections; (iii) height and uneven growth, making plants prone to lodging when hit by weather vagaries compounded by climate change; (iv) very low outputs resulting in high prices. Still, there remains high demand for tilak chandan and other traditional varieties due to their distinct sensory attributes of taste, texture and aroma linked to cultural and gastronomic heritage. To make these landraces more available and reliable in India’s current soil and climate conditions, we suggest incorporating their preferential characteristics into a form that is also high-yielding, drought tolerant and pest resistant
Chandan, a Multiple-Resistance Variety Released in Andhra Pradesh
No full textThis article 'Chandan, a Multiple-Resistance Variety Released in Andhra Pradesh' appeared in the International Rice Research Newsletter series, created by the International Rice Research Institute (IRRI). The primary objective of this publication was to expedite communication among scientists concerned with the development of improved technology for rice and for rice based cropping systems. This publication will report what scientists are doing to increase the production of rice in as much as this crop feeds the most densely populated and land scarce nations in the world
Interlayer Trions in 2D Transition-Metal Dichalcogenide Heterostructures
No full text© 2020, The Korean Physical Society. A dimensionally confined dielectric constant and reduced dielectric screening lead to two-dimensional transition-metal dichalcogenides (TMDs). The confined dielectric constant triggers a strong Coulomb interaction and high exciton binding energies between TMD heterostructures. Here we show a highly efficient interlayer charged exciton or trion formation and its generation sites are present in materials at room temperature. Two different transition metals (Mo, W) and chalcogenide (S, Se) elements were investigated in two different heterostructure combinations (MoS2—WS2 and MoSe2—WS2). Room temperature photoluminescence measurements demonstrate a highly efficient trion formation between and close to the heterostructure interfaces. This study highlights an effective band alignment, strong photoexciting Coulomb interaction, and formation of interlayer trions with different recombination energies. This investigation suggests the possibility of utilizing interlayer trions in promising optoelectronic devices in the future11sciescopuskc
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
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
Layer-by-layer hybrid chemical doping for high transmittance uniformity in graphene-polymer flexible transparent conductive nanocomposite
No full textA traditional transparent conducting film (TCF) such as indium tin oxide (ITO) exhibits poor mechanical flexibility and inconsistent transmittance throughout the UV-VIS-NIR spectrum. Recent TCFs like graphene films exhibit high sheet resistance (Rs) due to defect induced carrier scattering. Here we show a unique hybrid chemical doping method that results in high transmittance uniformity in a layered graphene-polymer nanocomposite with suppressed defect-induced carrier scattering. This layer-by-layer hybrid chemical doping results in low Rs (15 sq at >90% transmittance) and 3.6% transmittance uniformity (300-1000 nm) compared with graphene (17%), polymer (8%) and ITO (46%) films. The weak localization effect in our nanocomposite was reduced to 0.5%, compared with pristine (4.25%) and doped graphene films (1.2%). Furthermore, negligible Rs change (1.2 times compared to 12.6 × 103 times in ITO) and nearly unaltered transmittance spectra were observed up to 24 GPa of applied stress highlighting mechanical flexibility of the nanocomposite film. © 2018 The Author(s
Factors associated with minimum dietary diversity failure among Indian children
No full textAbstract Recognising the importance of infant and young child feeding practices during the first 2 years of life, the World Health Organization's Global Nutrition Monitoring Framework developed a minimum dietary diversity (MDD) indicator for feeding children aged 6–23 months. MDD is defined as the consumption of food items from five or more groups out of a total of eight food groups. Food intake from less than five food groups is considered minimum dietary diversity failure (MDDF). Using the nationally representative National Family Health Survey (NFHS) dataset, the present study assessed the trend in MDDF between 2005–6 and 2015–16 and the factors associated with MDDF among children aged 6–23 months during 2015–16. The NFHS conducted in 2005–6 and 2015–16 covered a sample of 14 419 and 74 078 children aged 6–23 months, respectively. Overall, the MDDF reduced from 87⋅4 % (95 % confidence interval (95 % CI) 86⋅8 %, 87⋅9 %) in 2005–6 to 80⋅6 % (95 % CI 80⋅1 %, 81⋅0 %) in 2015–16. Multivariable logistic regression analysis revealed that increased child's age, second and third birth order children, higher maternal age and education, mass media exposure of mothers and more than four antenatal care visits had a negative association with the MDDF. Children living in rural areas and residing in high-focus states of India were observed with higher odds of experiencing MDDF. Exposure to community healthcare services was negatively associated with MDDF, and anaemic children were more likely to have MDDF. Socioeconomic status of mothers and children and encouragement of maternal and child healthcare use could be helpful in devising context-specific intervention to mitigate MDDF
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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