Climate spectrum estimation in the presence of timescale errors.

We introduce an algorithm (called REDFITmc2) for spectrum estimation in the presence of timescale errors. It is based on the Lomb-Scargle periodogram for unevenly spaced time series, in combination with the Welch's Overlapped Segment Averaging procedure, bootstrap bias correction and persistence estimation. The timescale errors are modelled parametrically and included in the simulations for determining (1) the upper levels of the spectrum of the red-noise AR(1) alternative and (2) the uncertainty of the frequency of a spectral peak. Application of REDFITmc2 to ice core and stalagmite records of palaeoclimate allowed a more realistic evaluation of spectral peaks than when ignoring this source of uncertainty. The results support qualitatively the intuition that stronger effects on the spectrum estimate (decreased detectability and increased frequency uncertainty) occur for higher frequencies. The surplus information brought by algorithm REDFITmc2 is that those effects are quantified. Regarding timescale construction, not only the fixpoints, dating errors and the functional form of the age-depth model play a role. Also the joint distribution of all time points (serial correlation, stratigraphic order) determines spectrum estimation.

Bayesian estimation of the double hurdle model in the presence of fixed costs

We present a model of market participation in which the presence of non-negligible fixed costs leads to random censoring of the traditional double-hurdle model. Fixed costs arise when household resources must be devoted a priori to the decision to participate in the market. These costs, usually of time, are manifested in non-negligible minimum-efficient supplies and supply correspondence that requires modification of the traditional Tobit regression. The costs also complicate econometric estimation of household behavior. These complications are overcome by application of the Gibbs sampler. The algorithm thus derived provides robust estimates of the fixed-costs, double-hurdle model. The model and procedures are demonstrated in an application to milk market participation in the Ethiopian highlands.

Chaucer's presence in songes and sonettes

In an elegy to Wyatt published in Tottel’s Miscellany, Surrey claims that Wyatt ‘reft Chaucer the glory of his wit’. This statement, which both lauds and resists Chaucer, is a microcosm of the way Chaucer is treated throughout the Miscellany. In examining the collection’s paradoxical attitude to Chaucer, this essay focuses particularly on the Squire’s Tale, the Franklin’s Tale, Anelida and Arcite, the Legend of Good Women, and several short lyrics. In its interest in courtly love poetry and Petrarch, the Miscellany follows a trajectory in English poetry set by Chaucer. Its courtly verse is saturated with words, phrases, and tropes from his poetry. Rhyme royal, which he introduced into English poetry, is widely used. The Canterbury Tales has been fully assimilated and can be referred to allusively with the same confidence of the audience’s knowledge as is the case when referring to classical myth; in Wyatt’s ‘Myne owne Jhon Poins’, the speaker, disclaiming deceitfulness, says that he cannot ‘say that Pan/ Passeth Appollo in musike manifold:/ Praise syr Topas for a noble tale,/ And scorne the story that the knight tolde’ (lines 48-50). However, Chaucer’s poetry is also downplayed and contested in the Miscellany. ‘Truth’, the only poem of his which appears in the volume, is disingenuously placed in the ‘Uncertain Authors’ section. In addition, some of the most important elements of his work are strongly resisted in the Miscellany, either ignored, dismissed or challenged. These elements include Chaucer’s interest in variety of voice, his sympathetic engagement with women, particularly wronged women, and his interest in female speech and particularly female complaint. The Miscellany, by contrast, is dominated by male-voiced lyrics preoccupied with the pain inflicted on the lover by a lady who is frequently unfeeling, cruel, or faithless. Chaucer’s frequent focus on the cynical seduction and betrayal of female by male is reversed in the Miscellany, and the language and metaphors he uses to express male cruelty (e.g. the word ‘newfangleness’ and images of hooks, nets and traps) are usurped to describe the lady’s cruelty to the suffering lover. On occasion, poems in the Miscellany challenge specific Chaucerian texts; ‘On His Love Named White’ throws down a gauntlet to The Book of the Duchess, while two of Surrey’s poems implicitly take issue with the female falcon’s voice in the Squire’s Tale, giving the deceitful tercelet the opportunity to shout down the falcon’s charges. The essay thus shows that in many respects Tottel’s Miscellany is only superficially Chaucerian, and that it both passively and actively takes issue with Chaucer’s work.

Adapted customer relationship management implementation framework:facilitating value creation in nursing homes

This paper proposes a framework to support Customer Relationship Management (CRM) implementation in nursing homes. The work extends research by Cheng et al. (2005) who conducted in-depth questionnaires to identify critical features (termed value-characteristics), which are areas identified as adding the most value if implemented. Although Cheng et al. did proposed an implementation framework, summary of, and inconsistent inclusion of value-characteristics, limits the practical use of this contribution during implementation. In this paper we adapt the original framework to correct perceived deficiencies. We link the value characteristics to operational, analytical, strategic and/or collaborative CRM solution types, to allow consideration in context of practical implementation solutions. The outcome of this paper shows that, practically, a 'one solution meets all characteristic' approach to CRM implementation within nursing homes is inappropriate. Our framework, however, supports implementers in identifying how value can be gained when implementing a specific CRM solution within nursing homes; which subsequently support project management and expectation management.

"Where am I?" Impact of display and content variables on spatial presence and comprehension in virtual environments

Forgetting immediate physical reality and having awareness of one�s location in the simulated world is critical to enjoyment and performance in virtual environments be it an interactive 3D game such as Quake or an online virtual 3d community space such as Second Life. Answer to the question "where am I?" at two levels, whether the locus is in the immediate real world as opposed to the virtual world and whether one is aware of the spatial co-ordinates of that locus, hold the key to any virtual 3D experience. While 3D environments, especially virtual environments and their impact on spatial comprehension has been studied in disciplines such as architecture, it is difficult to determine the relative contributions of specific attributes such as screen size or stereoscopy towards spatial comprehension since most of them treat the technology as monolith (box-centered). Using a variable-centered approach put forth by Nass and Mason (1990) which breaks down the technology into its component variables and their corresponding values as its theoretical basis, this paper looks at the contributions of five variables (Stereoscopy, screen size, field of view, level of realism and level of detail) common to most virtual environments on spatial comprehension and presence. The variable centered approach can be daunting as the increase in the number of variables can exponentially increase the number of conditions and resources required. We overcome this drawback posed by adoption of such a theoretical approach by the use of a fractional factorial design for the experiment. This study has completed the first wave of data collection and starting the next phase in January 2007 and expected to complete by February 2007. Theoretical and practical implications of the study are discussed.

Evaluating relative impact of virtual reality system variables on architectural design comprehension and presence - A variable-centered approach using fractional factorial experiment

The relative contributions of five variables (Stereoscopy, screen size, field of view, level of realism and level of detail) of virtual reality systems on spatial comprehension and presence are evaluated here. Using a variable-centered approach instead of an object-centric view as its theoretical basis, the contributions of these five variables and their two-way interactions are estimated through a 25-1 fractional factorial experiment (screening design) of resolution V with 84 subjects. The experiment design, procedure, measures used, creation of scales and indices, results of statistical analysis, their meaning and agenda for future research are elaborated.

The mysterious presence of a 5-methylcytosine oxidase in the Drosophila genome: Possible explanations

5-methylcytosine is an important epigenetic modification involved in gene control in vertebrates and many other complex living organisms. Its presence in Drosophila has been a matter of debate and recent bisulfite sequencing studies of early-stage fly embryos have concluded that the genome of Drosophila is essentially unmethylated. However, as we outline here, the Drosophila genome harbors a well-conserved homolog of the TET protein family. The mammalian orthologs TET1/2/3 are known to convert 5-methylcytosine into 5-hydroxymethylcytosine. We discuss several possible explanations for these seemingly contradictory findings. One possibility is that the 2 modified cytosine bases are generated in Drosophila only at certain developmental stages and in a cell type-specific manner during neurogenesis. Alternatively, Drosophila Tet and its mammalian homologs may carry out catalytic activity-independent functions, and the possibility that these proteins may oxidize 5-methylcytosine in RNA created by the methyltransferase Dnmt2 should also be strongly considered.

On the generalized eigenvalue problem for the Rossby wave vertical velocity in the presence of mean flow and topography

In a series of papers, Killworth and Blundell have proposed to study the effects of a background mean flow and topography on Rossby wave propagation by means of a generalized eigenvalue problem formulated in terms of the vertical velocity, obtained from a linearization of the primitive equations of motion. However, it has been known for a number of years that this eigenvalue problem contains an error, which Killworth was prevented from correcting himself by his unfortunate passing and whose correction is therefore taken up in this note. Here, the author shows in the context of quasigeostrophic (QG) theory that the error can ulti- mately be traced to the fact that the eigenvalue problem for the vertical velocity is fundamentally a non- linear one (the eigenvalue appears both in the numerator and denominator), unlike that for the pressure. The reason that this nonlinear term is lacking in the Killworth and Blundell theory comes from neglecting the depth dependence of a depth-dependent term. This nonlinear term is shown on idealized examples to alter significantly the Rossby wave dispersion relation in the high-wavenumber regime but is otherwise irrelevant in the long-wave limit, in which case the eigenvalue problems for the vertical velocity and pressure are both linear. In the general dispersive case, however, one should first solve the generalized eigenvalue problem for the pressure vertical structure and, if needed, diagnose the vertical velocity vertical structure from the latter.

Regulating vertical relations in the presence of retailer differentiation costs

We discuss public policy towards vertical relations, comparing different types of contracts between a manufacturer and a maximum of two retailers. Together with (potential) price competition between the retailers, we study the role of a (sunk) differentiation cost paid by them in order to relax competition in the retail market and broaden the market potential of the distributed product. This non-price competition element in the downstream market is responsible for our conclusion that, unlike in standard policy guidelines and previous theoretical analysis, restrictions in intra-brand competition may deserve a permissive treatment even in the absence of inter-brand competition, if retailer differentiation is costly.

Forecasting US output growth with non-linear models in the presence of data uncertainty

We consider the impact of data revisions on the forecast performance of a SETAR regime-switching model of U.S. output growth. The impact of data uncertainty in real-time forecasting will affect a model's forecast performance via the effect on the model parameter estimates as well as via the forecast being conditioned on data measured with error. We find that benchmark revisions do affect the performance of the non-linear model of the growth rate, and that the performance relative to a linear comparator deteriorates in real-time compared to a pseudo out-of-sample forecasting exercise.

Real-time forecasting of inflation and output growth with autoregressive models in the presence of data revisions

We examine how the accuracy of real-time forecasts from models that include autoregressive terms can be improved by estimating the models on ‘lightly revised’ data instead of using data from the latest-available vintage. The benefits of estimating autoregressive models on lightly revised data are related to the nature of the data revision process and the underlying process for the true values. Empirically, we find improvements in root mean square forecasting error of 2–4% when forecasting output growth and inflation with univariate models, and of 8% with multivariate models. We show that multiple-vintage models, which explicitly model data revisions, require large estimation samples to deliver competitive forecasts. Copyright © 2012 John Wiley & Sons, Ltd.