45,877 research outputs found
The L-p-to-L-q boundedness of commutators with applications to the Jacobian operator
No full textSupplying the missing necessary conditions, we complete the characterisation of the L-p -> L-q boundedness of commutators [b, T] of pointwise multiplication and Calderon-Zygmund operators, for arbitrary pairs of 1 q, our results are new even for special classical operators with smooth kernels. As an application, we show that every f is an element of L-p(R-d) can be represented as a convergent series of normalised Jacobians J(u) = det del uof u is an element of (over dot(W))(1,dp)(R-d)(d). This extends, from p = 1 to p > 1, a result of Coifman, Lions, Meyer and Semmes about J:. (over dot(W))(1,d)(R-d)(d) -> H-1(R-d), and supports a conjecture of Iwaniec about the solvability of the equation Ju = f is an element of L-p(R-d). (C) 2021 The Author(s). Published by Elsevier Masson SAS.Peer reviewe
De Maiestate / Praeside M. Jacobo Thomasio, Moralis Philosoph. P. P., publice disputabit Johannes Dunte, R. L. Author & Respon: ad diem 9. Septembr. H L. Q. C.
No full textDE MAIESTATE / PRAESIDE M. JACOBO THOMASIO, MORALIS PHILOSOPH. P. P., PUBLICE DISPUTABIT JOHANNES DUNTE, R. L. AUTHOR & RESPON: AD DIEM 9. SEPTEMBR. H L. Q. C.
De Maiestate / Praeside M. Jacobo Thomasio, Moralis Philosoph. P. P., publice disputabit Johannes Dunte, R. L. Author & Respon: ad diem 9. Septembr. H L. Q. C. (1)
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Beiträge (21
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
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
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Raul Morin, author of 'Among the Valiant' shakes hands with Dr. Hector P. Garcia (photograph)
No full text(L. to R.): Raul Morin, author of 'Among the Valiant' shakes hands with Dr. Hector P. Garcia
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
Dissipation of Quasiclassical Turbulence in Superfluid 4He
No full textWe compare the decay of turbulence in superfluid 4He produced by a moving grid to the decay of turbulence in the same channel created by either an impulsive spin-down to rest or by intensive ion injection. In all cases the vortex line density L at late time t decays as L ~ t^-3/2. Below 0.8 K, the spin-down turbulence maintains initial rotation and decays slower than grid turbulence and ion-jet turbulence. This is presumably due to the decoupling of the superfluid component from the normal one at large length scales at low temperatures, thus changing its effective boundary condition from no-slip to slip
Outsourcing and Skill Imports: Foreign High-Skilled Workers on H-1B and L-1 Visas in the United States
No full textThis working paper looks in detail at the H-1B and L-1 visa programs for temporary employment in the United States. Based on official data from the US Citizenship and Immigration Services and the US Department of State, H-1B and L-1 visa issuance rapidly increased in the late 1990s, followed by a marked slowdown after 2001. This points to the highly cyclical nature of both visa programs. Indian nationals and immigrants working in computer-related occupations dominate the H1-B and L-1 population in the United States, but these two groups are also found to be the most cyclical segment, with very large declines in inflows after 2001. The total population of H-1B visaholders in 2003 is estimated to range between 387,000 and 746,000, of which 160,000 to 306,000 were Indian nationals. As all data on H-1B/L-1 visaholders are gross numbers and gross jobs data for comparable categories are absent, the extent of the impact of these visa programs on the US labor market cannot be gauged precisely. A broad range of US industries and educational institutions are found to be employing H-1B recipients, with the IT industry being the dominant sector. Evidence of aggressive wage-cost cutting, including paying H-1B recipients only the legally mandated 95 percent of the prevailing US wage, is found among some H-1B employers, although no systematic abuse of the system is present.Outsourcing, offshoring, high-skilled labor, immigration, H1B/L-1 visas
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
The stability of IQ in people with low intellectual ability: an analysis of the literature
No full textA meta-analysis of the stability of low IQ (IQ 80) was performed on IQ tests that have been
commonly used—tests that were derived by D. Wechsler (1949, 1955, 1974, 1981, 1991, 1997)
and those based on the Binet scales (L. M. Terman, 1960; L. M. Terman & Merrill, 1972). Weighted-
mean stability coefficients of .77 and .78 were found for Verbal IQ (V IQ) and Performance IQ
(P IQ) on the Wechsler tests and .82 for Full-Scale IQ (FS IQ) on both Wechsler and Binet tests,
for a mean test–retest interval of 2.8 years. Although the majority of FS IQs changed by less than
6 points, 14% changed by 10 points or more. The author suggests that the results of IQ assessment
should be treated with more caution than previously thought
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