333,161 research outputs found
q-Differential equations for q-classical polynomials and q-Jacobi-Stirling numbers
Full text linkWe introduce, characterise and provide a combinatorial interpretation for the so-called q-Jacobi–Stirling numbers.
This study is motivated by their key role in the (reciprocal) expansion of any power of a second order
q-differential operator having the q-classical polynomials as eigenfunctions in terms of other even order operators,
which we explicitly construct in this work. The results here obtained can be viewed as the q-version of
those given by Everitt et al. and by the first author, whilst the combinatorics of this new set of numbers is a
q-version of the Jacobi–Stirling numbers given by Gelineau and the second author
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
Full text linkBoth 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.
Optimal solution of the nearest correlation matrix problem by minimization of the maximum norm
Full text linkThe nearest correlation matrix problem is to find a valid (positive semidefinite) correlation matrix, R(m,m), that is nearest to a given invalid (negative semidefinite) or pseudo-correlation matrix, Q(m,m); m larger than 2. In the literature on this problem, 'nearest' is invariably defined in the sense of the least Frobenius norm. Research works of Rebonato and Jaeckel (1999), Higham (2002), Anjos et al. (2003), Grubisic and Pietersz (2004), Pietersz, and Groenen (2004), etc. use Frobenius norm explicitly or implicitly. However, it is not necessary to define 'nearest' in this conventional sense. The thrust of this paper is to define 'nearest' in the sense of the least maximum norm (LMN) of the deviation matrix (R-Q), and to obtain R nearest to Q. The LMN provides the overall minimum range of deviation of the elements of R from those of Q. We also append a computer program (source codes in FORTRAN) to find the LMN R from a given Q. Presently we use the random walk search method for optimization. However, we suggest that more efficient methods based on the Genetic algorithms may replace the random walk algorithm of optimization.Nearest correlation matrix problem; Frobenius norm; maximum norm; LMN correlation matrix; positive semidefinite; negative semidefinite; positive definite; random walk algorithm; Genetic algorithm; computer program; source codes; FORTRAN; simulation
Dynamics and Charge Fluctuations in Large-q Sachdev-Ye-Kitaev Lattices
Full text linkIt is known that the large- complex Sachdev-Ye-Kitaev (SYK) dot thermalizes instantaneously under rather general dynamical protocols. We consider a lattice of such dots coupled together, allowing for body hopping of particles between nearest neighbors. We develop a rather general analytical framework to study the dynamics to leading order in on such a lattice, allowing for arbitrary time dependent couplings, hence general dynamical protocols. We find that the physics of the diffusive case is effectively the same as the kinetic case , assuming . Remarkably, we find that the local charge densities form a closed set of equations. They however only show fluctuations of the order , hence remaining constant in the limit . Despite this effective lack of charge dynamics, the dots do not in fact behave as isolated lattice sites which would thermalize instantaneously. Indeed, we show via a proof by contradiction that such instantaneously thermalize is not generally possible for a connected lattice. Importantly, the results are shown to be independent of the dimensionality of the lattice.Same as published version with two minor typo corrections in Eqs. (4) and (8), 15 pages, 1 figur
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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Network Q
No full textA press release from Network Q announcing that they will begin featuring Brian McNaught, a gay columnist and author, for a monthly segment
Network Q
No full textA press release from Network Q announcing that they will begin featuring Brian McNaught, a gay columnist and author, for a monthly segment
Epidemiology of Brucellosis and Q Fever in Linked Human and Animal Populations in Northern Togo
Full text linkBACKGROUND:
Although brucellosis (Brucella spp.) and Q Fever (Coxiella burnetii) are zoonoses of global importance, very little high quality data are available from West Africa.
METHODS/PRINCIPAL FINDINGS:
A serosurvey was conducted in Togo's main livestock-raising zone in 2011 in 25 randomly selected villages, including 683 people, 596 cattle, 465 sheep and 221 goats. Additionally, 464 transhumant cattle from Burkina Faso were sampled in 2012. The serological analyses performed were the Rose Bengal Test and ELISA for brucellosis and ELISA and the immunofluorescence assay (IFA) for Q Fever Brucellosis did not appear to pose a major human health problem in the study zone, with only 7 seropositive participants. B. abortus was isolated from 3 bovine hygroma samples, and is likely to be the predominant circulating strain. This may explain the observed seropositivity amongst village cattle (9.2%, 95%CI:4.3-18.6%) and transhumant cattle (7.3%, 95%CI:3.5-14.7%), with an absence of seropositive small ruminants. Exposure of livestock and people to C. burnetii was common, potentially influenced by cultural factors. People of Fulani ethnicity had greater livestock contact and a significantly higher seroprevalence than other ethnic groups (Fulani: 45.5%, 95%CI:37.7-53.6%; non-Fulani: 27.1%, 95%CI:20.6-34.7%). Appropriate diagnostic test cut-off values in endemic settings requires further investigation. Both brucellosis and Q Fever appeared to impact on livestock production. Seropositive cows were more likely to have aborted a foetus during the previous year than seronegative cows, when adjusted for age. This odds was 3.8 times higher (95%CI: 1.2-12.1) for brucellosis and 6.7 times higher (95%CI: 1.3-34.8) for Q Fever.
CONCLUSIONS:
This is the first epidemiological study of zoonoses in Togo in linked human and animal populations, providing much needed data for West Africa. Exposure to Brucella and C. burnetii is common but further research is needed into the clinical and economic impact
Tobin's Q and Financial Policy
Full text linkRecent research in macroeconomics has emphasized the importance of linking the financial and real sectors and the need for working with optimizing models. Tobin’s Q model of investment would appear to provide a framework that can satisfy these two criteria. In contrast to the original presentation of the Q model, the formal development has not recognized that the firm actively participates in a number of financial markets; in this broader context, we show that Q is likely to be an uninformative and possibly misleading signal for investment expenditures . We then endeavor to turn this negative theoretical result to positive advantage in resolving a number of empirical problems with Q models, but the modifications dictated by the theory receive little support from the data.
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