63,012 research outputs found
On Sketching the q to p Norms
No full textWe initiate the study of data dimensionality reduction, or sketching, for the q -> p norms. Given an n x d matrix A, the q -> p norm, denoted |A |_{q -> p} = sup_{x in R^d \ 0} |Ax |_p / |x |_q, is a natural generalization of several matrix and vector norms studied in the data stream and sketching models, with applications to datamining, hardness of approximation, and oblivious routing. We say a distribution S on random matrices L in R^{nd} - > R^k is a (k,alpha)-sketching family if from L(A), one can approximate |A |_{q -> p} up to a factor alpha with constant probability. We provide upper and lower bounds on the sketching dimension k for every p, q in [1, infty], and in a number of cases our bounds are tight. While we mostly focus on constant alpha, we also consider large approximation factors alpha, as well as other variants of the problem such as when A has low rank
Spark Monitor 0.0.8
No full text<p>Jupyter extension to monitor Apache Spark from notebooks.</p>
<p>Available at:</p>
<p>https://github.com/krishnan-r/sparkmonitor</p>
Effect of Mach number on the structure of turbulent spots
No full textDirect numerical simulations have been performed to study the dynamics of isolated turbulent spots in compressible isothermal-wall boundary layers. Results of a bypass transition scenario at Mach 2, 4 and 6 are presented. At all Mach numbers the evolved spots have a leading-edge overhang, followed by a turbulent core and a calmed region at the rear interface. The spots have an upstream-pointing arrowhead shape when visualized by near-wall slices, but a downstream-pointing arrowhead in slices away front the wall. The lateral spreading of the spot decreases substantially with the Mach number, consistent with a growth mechanism based on the instability of lateral shear layers. Evidence for a supersonic (Mach) mode substructure is found in the Mach 6 case, where coherent spanwise structures are observed under the spot overhang region
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
On the merging of turbulent spots in a supersonic boundary-layer flow
No full textThe complex transition flow physics associated with the merging of turbulent spots in a Mach 2 boundary-layer has been studied using direct numerical simulation. Dynamics of an isolated turbulent spot, merging of laterally displaced spots, and merging of two spots in tandem are considered. The coherent structures associated with the wingtip region of the spot are found to play a major role in destabilising the surrounding laminar fluid. In the merging of laterally displaced spots a strong velocity defect, resulting in unstable inflectional velocity profiles, is observed in the interaction zone. These local inflectional instabilities within the interaction region trigger new large scale coherent structures. During the inline merging, the calmed region behind the tail of the downstream spot is found to suppress the growth of the upstream spot. The upstream spot is ultimately engulfed by the downstream spot
Supplementary_material – Supplemental material for Abrupt climate change at ~2800 yr BP evidenced by a stalagmite record from peninsular India
No full textSupplemental material, Supplementary_material for Abrupt climate change at ~2800 yr BP evidenced by a stalagmite record from peninsular India by Nitesh Sinha, Naveen Gandhi, S Chakraborty, R Krishnan, MG Yadava and R Ramesh in The Holocene</p
Letter from John P. John to Joseph R. Goodman, 1942
No full textLetter from John P. John to Joseph R. Goodman: "Here are a couple of letters Caleb received concerning the Japanese situation. I have already sent him a condensed record of their general text. Probably more material will be coming in from time to time and we will forward it to you. I guess this is sufficient since Caleb has spoken with you in detail about the problem and where he is to be contacted in the east. Louise Thompson and I are holding things down while Caleb is away and can be contacted here by mail for anything."Personal correspondence, organizational records, government documents, publications, and other papers created or collected by Joseph R. Goodman documenting the forced removal and incarceration of Japanese Americans during World War II, as well as organized resistance to incarceration. Included in the collection are records of the Japanese Young Men's Christian Association and the Japanese American Citizens' League in San Francisco, including papers of the Japanese YMCA's executive secretary Lincoln Kanai; Sakai family papers; Goodman's correspondence to and from Japanese American incarcerees, organizations opposing forced removal and incarceration of Japanese Americans, the War Relocation Authority, and others; publications, photographs, and ephemera from the Topaz Relocation Center, where Goodman taught high school; War Relocation Authority records and publications; and newspaper clippings, pamphlets, and reports about forced removal and incarceration created by various government, religious, and civic organizations, in California and nationwide
Environmentally Benign Marine Antifouling Coatings
No full textThis
document is a submitted
work that was subsequently published as a book chapter by Alpha Science International Limited.S. Krishnan, Environmentally Benign Marine Antifouling Coatings, in Biofilm Control in Biomedical and Industrial Environments, edited by P. S. Murthy, R. Sekar and V. Thiyagarajan (Alpha Science International Ltd., Oxford, U.K., 2019), ISBN 978-1-78332-393-7, Chapter 7, pp. 7.1–7.30.</div
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Replication Data for: A Regression Analysis of the probability of a recession and student loan debt utilizing data between 1993-2019
No full textOver 44.7 million Americans carry student loan debt, with the total amount valued at approximately $1.31 trillion (Quarterly Report, 2019). Ergo, consumer spending, a factor of GDP, is stifled and negatively impacts the economy (Frizell, 2014, p. 22). This study examined the relationship between student loan debt and the probability of a recession in the near future, as well as the effects of proposed student loan forgiveness policies through the use of a created model. The Federal Reserve Bank of St. Louis’s website (FRED) was used to extract data regarding total GDP per quarter and student loan debt per quarter ("Federal Reserve Economic Data," 2019). Through the combination of the student loan debt per quarter and total GDP per quarter datasets, the percentage of total GDP composed of student loan debt per quarter was calculated and fitted to a logistic curve. Future quarterly values for total GDP and the percentage of total GDP composed by student loan debt per quarter were found through Long Short Term Models and Euler’s Method, respectively. Through the creation of a probability of recession index, the probability of recession per quarter was compared to the percentage of total GDP composed by student loan debt per quarter to construct an exponential regression model. Utilizing a primarily quantitative method of analysis, the percentage of total GDP composed by student loan debt per quarter was found to be strongly associated[p < 1.26696* 10-8]with the probability of recession per quarter(p(R)), with the p(R) tending to peak as the percentage of total GDP composed of student loan debt per quarter strayed away from the carrying capacity of the logistic curve. Inputting the student loan debt forgiveness policies of potential congressional bills proposed by lawmakers found that eliminating 49.7 % and 36.7% of student loan debt would reduce the recession probabilities to be 1.73545*10-29% and 9.74474*10-25%, respectively
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