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Search Results: 1 - 10 of 297795 matches for " J. Dick "
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A characterization of Sobolev spaces on the sphere and an extension of Stolarsky's invariance principle to arbitrary smoothness
J. Brauchart,J. Dick
Mathematics , 2012, DOI: 10.1007/s00365-013-9217-z
Abstract: In this paper we study reproducing kernel Hilbert spaces of arbitrary smoothness on the sphere $\mathbb{S}^d \subset \mathbb{R}^{d+1}$. The reproducing kernel is given by an integral representation using the truncated power function $(\boldsymbol{x} \cdot \boldsymbol{z} - t)_+^{\beta-1}$ defined on spherical caps centered at $\boldsymbol{z}$ of height $t$, which reduce to an integral over indicator functions of spherical caps as studied in [J. Brauchart, J. Dick, arXiv:1101.4448v1 [math.NA], to appear in Proc. Amer. Math. Soc.] for $\beta = 1$. This is in analogy to the generalization of the reproducing kernel to arbitrary smoothness on the unit cube. We show that the reproducing kernel is a sum of a Kamp{\'e} de F{\'e}riet function and the Euclidean distance $\|\boldsymbol{x}-\boldsymbol{y}\|$ of the arguments of the kernel raised to the power of $2\beta -1$ if $2\beta - 1$ is not an even integer; otherwise the logarithm of the distance $\|\boldsymbol{x}-\boldsymbol{y}\|$ appears. For $\beta \in \mathbb{N}$ the Kamp\'e de F\'eriet function reduces to a polynomial, giving a simple closed form expression for the reproducing kernel. Using this space we can generalize Stolarsky's invariance principle to arbitrary smoothness. Previously, Warnock's formula, which is the analogue to Stolarsky's invariance principle for the unit cube $[0,1]^s$, has been generalized using similar techniques [J. Dick, Ann. Mat. Pura. Appl., (4) 187 (2008), no. 3, 385--403].
Does Consciousness Collapse the Wave Function
Dick J. Bierman
Physics , 2003,
Abstract: A conceptual replication of the Hall-experiment to test the 'subjective reduction' interpretation of the measurement problem in Quantum Physics is reported. Two improvements are introduced. First the delay between pre-observation and final observation of the same quantum event is increased from a few microseconds in the original experiment to 1 second in this replication. Second, rather than using the observers conscious response as the dependent variable, we use the early brain responses as measured by EEG. These early responses cover a period where the observer is not yet conscious of the quantum event. Results support the 'subjective reduction' hypothesis because significant differences between the brain responses of the final observer are found dependent upon the pre-observer looking or not looking at the quantum event (exact binomial p < 0.02). Alternative 'normal' explanations are discussed and rejected. It is concluded that the present results do justify further research along these lines.
THE CHARGE OF THE LIGHT BRIGADE And South Africa's Very Own Pony
H.J. Dick Usher
Scientia Militaria : South African Journal of Military Studies , 2012, DOI: 10.5787/14-1-531
Abstract: The story of the cavalry charge which I shall relate might have been forgotten by now had it not been immortalized by Alfred Lord Tennyson in his poem, 'The Charge of the Light Brigade.' Two stanzas from that work appear in this article. The Crimean War (1853-1856) was so named because nearly all the fighting took place in the Crimea, a peninsula north of the Black Sea. Russia was a large country with few seaports. The Black Sea lies to the south of Russia, but part of the shores of the Black Sea belonged to Turkey and the Turks could keep the ships of other nations away from their shores. For this reason Russia planned to take possession of Turkey and offered to divide it, when conquered, with Britain. But Britain was not interested, and also did not want Russia to gain too much power. In the Crimean War the Allies consisted of Turkey, France, Sardinia, and Britain. The war was ended by the Treaty of Paris in 1856.
BRITISH ARMY COMMISIONS BY PURCHASE
H.J. Dick Usher
Scientia Militaria : South African Journal of Military Studies , 2012, DOI: 10.5787/8-4-766
Abstract: I have before me a copy of a letter dated 12 May, 1814, written by certain Lieutenant-Colonel William Fuller of the King's Dragoon Guards to a British Lord, in which is advised that a commission for His Lordship's son would cost £735. Further on in this article I shall state the prices as they were at the time of the' Crimean War. Only recently did I read a book by a very well-known British author who claims that the British army of the 1850's was small, and that the Crimean War was to prove that it was shockingly organised, but he speaks only well of the navy of that period. I ask that my readers please bear in mind that in earlier days there was no such rank as second-lieutenant nor sub-lieutenant in the British army. The most junior commissioned rank in the infantry was that of ensign. In the cavalry, it was cornet until 1871, when it became sub-lieutenant.
Supertranslations to All Orders*  [PDF]
Rainer Dick
Journal of Modern Physics (JMP) , 2010, DOI: 10.4236/jmp.2010.11007
Abstract: We calculate the transformation laws of the general linear superfield and chiral superfields under supertranslations to all orders in the translation parameters . We use the superfield formalism with complete expansions of the component fields in the coordinate shifts . The results show in particular how a general supertranslation transforms each component field of a supermultiplet into a complete superfield. The results also provide complete parametri-zations of orbits of component fields under supertranslations.
Swallowing threshold parameters of subjects with complete dentures and overdentures  [PDF]
Dick. J. Witter, F. Anneke Tekamp, Ad P. Slagter, Cees M. Kreulen, Nico H. J. Creugers
Open Journal of Stomatology (OJST) , 2011, DOI: 10.4236/ojst.2011.13012
Abstract: Aim: To compare the chewing process and swallowing threshold parameters of subjects with complete dentures and overdentures with data obtained from subjects with complete natural dentitions. Metho-dology: The chewing process in terms of swallowing threshold parameters of four groups of subjects with complete dentures (all females) was quantified by sieving particles after chewing of an artificial test ‘food’ and compared with that of subjects with com-plete natural dentitions as a reference group (33 sub-jects). All subjects (except those of the reference group) had a complete denture in the upper jaw. Regarding the lower jaw two groups with complete dentures (with high (24 subjects), respectively low mandible (12 subjects)) and two groups with overdentures (implant-retained (22 subjects), respectively natural root supported (19 subjects)) were composed. Results: The ‘overdenture-implants’ group needed significantly more chewing cycles and time (mean: 45 cycles in 32 seconds) until ‘swallowing’ compared to the group with complete natural dentitions (mean: 26 cycles in 19 seconds until ‘swallowing’). Also the ‘complete denture-low mandible’ group needed sig-nificantly more cycles and time (mean: 52 cycles in 44 seconds) until ‘swallowing’ than the complete dentition group. In the ‘overdenture-natural roots’ group these outcomes (33 cycles in 24 seconds) were not significantly different compared with the complete dentition group. The ‘complete denture-high mandi-ble’ group (32 cycles in 26 seconds) needed not sig-nificantly more cycles until ‘swallowing’, however time until ‘swallowing’ was significantly longer com-pared to the complete dentition group. All denture groups had significantly larger mean particle sizes when ‘swallowing’ (sizes in the order of 3 mm) than the natural dentition group (about 2 mm). Conclusion: Despite efforts to compensate for a reduced chewing efficiency, subjects with complete dentures (including overdentures) had 50% larger median particle sizes when ‘swallowing’ compared to subjects with complete natural dentitions.
A Vietnamese version of the 14-item oral health impact profile (OHIP-14VN)  [PDF]
Anneloes E. Gerritsen, Thoa C. Nguyen, Dick J. Witter, Ewald M. Bronkhorst, Nico H. J. Creugers
Open Journal of Epidemiology (OJEpi) , 2012, DOI: 10.4236/ojepi.2012.21005
Abstract: Aim: To validate a Vietnamese short version (OHIP- 14VN) for use in epidemiological studies. Methods: The original English-language version was translated into Vietnamese, back translated and after some revisions tested for psychometric properties. Subjects (n = 724) were asked to self-administer a questionnaire but could ask for assistance. Convergent validity was tested by investigating associations between OHIP domain and total scores, and dichotomized self-reported satisfaction with 1) the dentition in general, 2) chewing function, and 3) esthetics. Groups validity was evaluated by comparing OHIP scores of subjects having ≤6 molars vs. >6 molars and tooth decay vs. no decay. Test-retest reliability was investigated in a convenience sample (n = 54) and expressed in Intraclass Correlation Coefficients (ICCs). Internal consistency was assessed by Cronbach’s alpha and average interitem correlation coefficients. Results: Validity: all associations were in the hypothesized directions. Differences in mean OHIP total were statistically sig-nificant for all discriminative variables. OHIP scores completed with assistance were significantly lower than those from self-administered questionnaires and therefore analyzed separately. For both administration formats differences in mean scores were still significant for “satisfaction” but for having ≤6 molars or decay the differences lost significance for most domain and total scores. Reliability: ICCs ranged from 0.54 - 0.74. Internal consistency: Cronbach’s alphas for OHIP total scores were 0.93 (self-administered) and 0.91 (with assistance). Average interitem correlation coefficients ranged from 0.26 - 0.67 (self-administered) and 0.28 - 0.69 (with assistance). Conclusions: This Vietnamese version of the OHIP-14 demonstrated good construct validity and acceptable reliability for OHIP total scores however OHIP-14VN domain scores should be interpreted with caution.
Incorporating Genetics into Your Studies: A Guide for Social Scientists
Danielle M. Dick,Shawn J. Latendresse
Frontiers in Psychiatry , 2011, DOI: 10.3389/fpsyt.2011.00017
Abstract: There has been a surge of interest in recent years in incorporating genetic components into on-going longitudinal, developmental studies and related psychological studies. While this represents an exciting new direction in developmental science, much of the research on genetic topics in developmental science does not reflect the most current practice in genetics. This is likely due, in part, to the rapidly changing landscape of the field of genetics, and the difficulty this presents for developmental scientists who are trying to learn this new area. In this review, we present an overview of the paradigm shifts that have occurred in genetics and we introduce the reader to basic genetic methodologies. We present our view of the current stage of research ongoing at the intersection of genetics and social science, and we provide recommendations for how we could do better. We also address a number of issues that social scientists face as they integrate genetics into their projects, including choice of a study design (candidate gene versus genome-wide association versus sequencing), different methods of DNA collection, and special considerations involved in the analysis of genotypic data. Through this review, we hope to equip social scientists with a deeper understanding of the many considerations that go into genetics research, in an effort to foster more meaningful cross-disciplinary initiatives.
Consistency of Markov chain quasi-Monte Carlo on continuous state spaces
S. Chen,J. Dick,A. B. Owen
Statistics , 2011, DOI: 10.1214/10-AOS831
Abstract: The random numbers driving Markov chain Monte Carlo (MCMC) simulation are usually modeled as independent U(0,1) random variables. Tribble [Markov chain Monte Carlo algorithms using completely uniformly distributed driving sequences (2007) Stanford Univ.] reports substantial improvements when those random numbers are replaced by carefully balanced inputs from completely uniformly distributed sequences. The previous theoretical justification for using anything other than i.i.d. U(0,1) points shows consistency for estimated means, but only applies for discrete stationary distributions. We extend those results to some MCMC algorithms for continuous stationary distributions. The main motivation is the search for quasi-Monte Carlo versions of MCMC. As a side benefit, the results also establish consistency for the usual method of using pseudo-random numbers in place of random ones.
Spatial analysis of BSE cases in the Netherlands
Lourens Heres, Dick J Brus, Thomas J Hagenaars
BMC Veterinary Research , 2008, DOI: 10.1186/1746-6148-4-21
Abstract: We have found three spatial case clusters in the Dutch BSE epidemic. The clusters are geographically distinct and each cluster appears in a different birth cohort. When testing all birth cohorts together, only one significant cluster was detected. The fact that we found stronger spatial clustering when using a cohort-based analysis, is consistent with the evidence that most BSE infections occur in animals less than 12 or 18 months old.Significant spatial case clustering is present in the Dutch BSE epidemic. The spatial clusters of BSE cases are most likely due to time-dependent heterogeneities in exposure related to feed production.Disease clustering patterns may provide important clues to the nature of disease transmission. In the context of BSE in cattle, clustering can be defined as cases not being completely randomly distributed amongst farms. We speak of spatial clustering if cases are more likely to occur in geographic proximity to other cases. after correcting for spatial differences in density of cattle.BSE cases first occurred in the Netherlands in 1997. After a peak of 24 cases in 2002 the epidemic has now much declined. In Table 1 we list the chronology of introduction of the different BSE control measures in the Netherlands. The majority of Dutch BSE cases were born after the introduction of a ban on ruminant Meat-and-Bone Meal (MBM) in ruminant feed in 1989, and the results of a case-control study [1] indicate that cross-contamination of ruminant feed with MBM from pig or poultry feed has been the main cause of these cases.As the transmission of BSE is at least predominantly feed-borne, case clustering patterns differ from patterns caused by infectious spread via direct transmission between hosts. In particular, none of the farms with BSE in The Netherlands (82 farms in total) has had more than one animal diagnosed [1].Although this paper deals with a spatial analysis of the BSE case data, we find it useful to discuss the possible clustering mechanisms
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