9,554 research outputs found
Tensor spherical harmonics on S^2 and S^3 as eigenvalue problems
Tensor spherical harmonics for the 2‐sphere and 3‐sphere are discussed as eigenfunction problems of the Laplace operators on these manifolds. The scalar, vector, and second‐rank tensor harmonics are given explicitly in terms of known functions and their properties summarized
Immigration and Domestic Politics in South Africa: Contradictions of the Rainbow Nation
The region of Southern Africa has been part of the global capitalist system since its inception in the late 15th century, when Portugal incorporated Angola and Mozambique into its empire. In 1652 the Dutch East India Company established a refreshment station at the Cape of Good Hope for ships travelling between Europe and the Far East.1 From that time the region has experienced several periods of deepening incorporation into the global system
More Letter Conundrums
It\u27s time to resurrect the letter conundrum from the nineteenth century with some up-to-date examples
How to Name the Residents
I read Mary Stewart Craig\u27s article Do Mamaroneckers Like to Neck? in the November issue of Word Ways with great relish. As an upstanding citizen, I immediately sat down and set down some regional epithets that popped into my head, trying to follow her example. I mailed them to Word Ways and returned to my mystery novel. In a few days I received a note from the editor, suggesting that I elucidate and illustrate those principles that make for clever citizens\u27 names
UNIVERSITIES AND AID: A HISTORY OF THEIR PARTNERSHIP IN TECHNICAL ASSISTANCE FOR DEVELOPING COUNTRIES
International Development,
Exploring modality switching effects in negated sentences: further evidence for grounded representations
Theories of embodied cognition (e.g., Perceptual Symbol Systems Theory; Barsalou, 1999, 2009) suggest that modality specific simulations underlie the representation of concepts. Supporting evidence comes from modality switch costs: participants are slower to verify a property in one modality (e.g., auditory, BLENDER-loud) after verifying a property in a different modality (e.g., gustatory, CRANBERRIES-tart) compared to the same modality (e.g., LEAVES-rustling, Pecher et al., 2003). Similarly, modality switching costs lead to a modulation of the N400 effect in event-related potentials (ERPs; Collins et al., 2011; Hald et al., 2011). This effect of modality switching has also been shown to interact with the veracity of the sentence (Hald et al., 2011). The current ERP study further explores the role of modality match/mismatch on the processing of veracity as well as negation (sentences containing “not”). Our results indicate a modulation in the ERP based on modality and veracity, plus an interaction. The evidence supports the idea that modality specific simulations occur during language processing, and furthermore suggest that these simulations alter the processing of negation
Total Width of 125 GeV Higgs Boson
By using the LHC and Tevatron measurements of the cross sections to various
decay channels relative to the standard model Higgs boson, the total width of
the putative 125 GeV Higgs boson is determined as 6.1 +7.7-2.9 MeV. We describe
a way to estimate the branching fraction for Higgs decay to dark matter. We
also discuss a No-Go theorem for the gammagamma signal of the Higgs boson at
the LHC.Comment: 11 pages, 2 figure
What motivates African-American charitable giving: findings from a national sample
Given the growing wealth of minority families in America, including that of African-American families, the potential for charitable donations from these households is much greater. The purpose of this secondary analysis is to examine those variables that may influence African-American charitable giving patterns. This study uses the Panel Study of Income Dynamics (PSID) data to analyze the effects of multiple factors on the giving habits of African-Americans. Based on this study\u27s findings, social workers employed as executive directors or fund-raisers in private nonprofit organizations may want to identify and cultivate individual African-American donors directly, instead of relying on United Way and other federated campaigns
Maximum likelihood and pseudo score approaches for parametric time-to-event analysis with informative entry times
We develop a maximum likelihood estimating approach for time-to-event Weibull
regression models with outcome-dependent sampling, where sampling of subjects
is dependent on the residual fraction of the time left to developing the event
of interest. Additionally, we propose a two-stage approach which proceeds by
iteratively estimating, through a pseudo score, the Weibull parameters of
interest (i.e., the regression parameters) conditional on the inverse
probability of sampling weights; and then re-estimating these weights (given
the updated Weibull parameter estimates) through the profiled full likelihood.
With these two new methods, both the estimated sampling mechanism parameters
and the Weibull parameters are consistently estimated under correct
specification of the conditional referral distribution. Standard errors for the
regression parameters are obtained directly from inverting the observed
information matrix in the full likelihood specification and by either
calculating bootstrap or robust standard errors for the hybrid pseudo
score/profiled likelihood approach. Loss of efficiency with the latter approach
is considered. Robustness of the proposed methods to misspecification of the
referral mechanism and the time-to-event distribution is also briefly examined.
Further, we show how to extend our methods to the family of parametric
time-to-event distributions characterized by the generalized gamma
distribution. The motivation for these two approaches came from data on time to
cirrhosis from hepatitis C viral infection in patients referred to the
Edinburgh liver clinic. We analyze these data here.Comment: Published in at http://dx.doi.org/10.1214/14-AOAS725 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
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