7,828 research outputs found
Insights from Industry Leaders: A Maturity Model for Strengthening Communication Measurement and Evaluation
Much scholarship has been devoted to identifying barriers that prevent the advancement of communication measurement and evaluation. This research focuses on the characteristics, objectives, and practices of chief communication officers (CCOs) with successful measurement and evaluation programs. Three key dimensions of practice emerged from in-depth interviews: communication executives’ measurement practices and evaluation programs were used to adjust communication strategies; were aligned with other business units; and were integrated with business priority plans. Interviewees also focused on the ability of communication measurement practices and evaluation programs to provide insights for executives, to align communication with the work of other business units, and to connect the organization with the outside environment and stakeholders. This study extends strategic communication scholarship by discussing how overcoming barriers and advancing measurement and evaluation work relates to roles adopted by organizational leaders. This article also offers a preliminary, scalable maturity model that aids in the development, formalization, and optimization of strategic communication measurement and evaluation. This study demonstrates the capacity for communication evaluation to overcome perceived barriers, realize appropriate stature with organizations, and grow communication functions accordingly
First-passage theory of exciton population loss in single-walled carbon nanotubes reveals micron-scale intrinsic diffusion lengths
One-dimensional crystals have long range translational invariance which
manifests as long exciton diffusion lengths, but such intrinsic properties are
often obscured by environmental perturbations. We use a first-passage approach
to model single-walled carbon nanotube (SWCNT) exciton dynamics (including
exciton-exciton annihilation and end effects) and compare it to results from
both continuous-wave and multi-pulse ultrafast excitation experiments to
extract intrinsic SWCNT properties. Excitons in suspended SWCNTs experience
macroscopic diffusion lengths, on the order of the SWCNT length, (1.3-4.7 um)
in sharp contrast to encapsulated samples. For these pristine samples, our
model reveals intrinsic lifetimes (350-750 ps), diffusion constants (130-350
cm^2/s), and absorption cross-sections (2.1-3.6 X 10^-17 cm^2/atom) among the
highest previously reported.and diffusion lengths for SWCNTs.Comment: 6 pages, 3 figure
Physical activity is prospectively associated with adolescent nonalcoholic fatty liver disease
Objectives: The aim of the present study was to assess whether objectively measured physical activity at mean ages 12 and 14 years are prospectively associated with ultrasound scan liver fat and stiffness (alanine aminotransferase, aspartate aminotransferase [AST], and [gamma]-glutamyl transferase [GGT]) assessed at mean age 17.8 years.
Methods: Participants were from the Avon Longitudinal Study of Parents and Children. Total physical activity (counts per minute) and minutes of moderate to vigorous physical activity (MVPA) were measured using ActiGraph accelerometers at mean ages 12 and 14 years.
Results: Greater total physical activity and MVPA at ages 12 and 14 years were associated with lower odds of liver fat and lower GGT levels at mean age 17.8 years, such as per 15-minute increase in daily MVPA at age 12 years, the confounder adjusted odds ratio of liver fat was 0.47 (95% confidence interval [CI] 0.27–0.84). Associations attenuated after additional adjustment for fat mass as a potential confounder (eg, per 15-minute increase in daily MVPA at age 12 years, the odds ratio of liver fat attenuated to 0.65 [95% CI 0.35–1.21]) or a potential mediator (eg, per 15-minute increase in daily MVPA at age 12 years the odds ratio of liver fat attenuated to 0.59 [95% CI 0.32–1.09]). Results did not further attenuate after additional adjustment for insulin resistance. There was some evidence that greater total physical activity and MVPA at age 12 years were associated with the higher AST levels.
Conclusions: Adolescents who were more active in childhood have lower odds of fatty liver and lower GGT levels. These findings are likely to be, at least in part, explained by adiposity
Modelling yarn balloon motion in ring spinning
Air-drag on a ballooning yarn and balloon shape affect the yarn tension and ends-down (yarn breakage), which in turn affects energy consumption and yarn productivity in ring spinning. In this article, a mathematical model of yarn ballooning motion in ring spinning is established. The model can be used to generate balloon shape and predict tension in the ballooning yarn under given spinning conditions. Yarn tension was measured using a computer data acquisition system and the balloon shapes were captured using a digital camera with video capability during the experiments using cotton and wool yarns at various balloon-heights and with varying yarn-length in the balloon. The air-drag coefficients on ballooning cotton and wool yarns in ring spinning were estimated by making a “best fit” between the theoretical and experimental turning points. The theoretical results were verified with experimental data. The effects of air-drag and balloon shape on yarn tension are discussed
Testing For Nonlinearity Using Redundancies: Quantitative and Qualitative Aspects
A method for testing nonlinearity in time series is described based on
information-theoretic functionals -- redundancies, linear and nonlinear forms
of which allow either qualitative, or, after incorporating the surrogate data
technique, quantitative evaluation of dynamical properties of scrutinized data.
An interplay of quantitative and qualitative testing on both the linear and
nonlinear levels is analyzed and robustness of this combined approach against
spurious nonlinearity detection is demonstrated. Evaluation of redundancies and
redundancy-based statistics as functions of time lag and embedding dimension
can further enhance insight into dynamics of a system under study.Comment: 32 pages + 1 table in separate postscript files, 12 figures in 12
encapsulated postscript files, all in uuencoded, compressed tar file. Also
available by anon. ftp to santafe.edu, in directory pub/Users/mp/qq. To be
published in Physica D., [email protected]
Antigen-driven T-cell turnover.
A mathematical model is developed to characterize the distribution of cell turnover rates within a population of T lymphocytes. Previous models of T-cell dynamics have assumed a constant uniform turnover rate; here we consider turnover in a cell pool subject to clonal proliferation in response to diverse and repeated antigenic stimulation. A basic framework is defined for T-cell proliferation in response to antigen, which explicitly describes the cell cycle during antigenic stimulation and subsequent cell division. The distribution of T-cell turnover rates is then calculated based on the history of random exposures to antigens. This distribution is found to be bimodal, with peaks in cell frequencies in the slow turnover (quiescent) and rapid turnover (activated) states. This distribution can be used to calculate the overall turnover for the cell pool, as well as individual contributions to turnover from quiescent and activated cells. The impact of heterogeneous turnover on the dynamics of CD4(+) T-cell infection by HIV is explored. We show that our model can resolve the paradox of high levels of viral replication occurring while only a small fraction of cells are infected
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Stepping stones to the Neolithic? Radiocarbon dating the Early Neolithic on islands within the ‘western seaways’ of Britain
The western seaways – an arc of sea stretching from the Channel Islands in the south, up through the Isles of Scilly, the Isle of Man and the Outer Hebrides to Orkney in the north – have long been seen as crucial to our understanding of the processes which led to the arrival of the Neolithic in Britain and Ireland in the centuries around 4000 BC. The western seaways have not, however, been considered in detail within any of the recent studies addressing the radiocarbon chronology of the Earliest Neolithic in that wider region. This paper presents a synthesis of all existing 5th and 4th millennia cal BC radiocarbon dates from islands within the western seaways, including 50 new results obtained specifically for this study. While the focus here is insular in a literal sense, the project’s results have far reaching implications for our understanding of the Mesolithic-Neolithic transition across Britain and Ireland and beyond. The findings broadly fit well with Whittle et al.’s (2011) Gathering Time model, suggesting that the earliest dated Neolithic in this zone falls into the c. 3900-3700 cal BC bracket. However, it is also noted that our current chronological understanding is based on comparatively few dates spread across a large area. Consequently, it is suggested that both further targeted work and an approach that incorporates an element of typo-chronology (as well as absolute dating) is necessary if we are to move our understanding of the process of transition in this key region forward
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Identification of a candidate gene for a QTL for spikelet number per spike on wheat chromosome arm 7AL by high-resolution genetic mapping.
Key messageA high-resolution genetic map combined with haplotype analyses identified a wheat ortholog of rice gene APO1 as the best candidate gene for a 7AL locus affecting spikelet number per spike. A better understanding of the genes controlling differences in wheat grain yield components can accelerate the improvements required to satisfy future food demands. In this study, we identified a promising candidate gene underlying a quantitative trait locus (QTL) on wheat chromosome arm 7AL regulating spikelet number per spike (SNS). We used large heterogeneous inbred families ( > 10,000 plants) from two crosses to map the 7AL QTL to an 87-kb region (674,019,191-674,106,327 bp, RefSeq v1.0) containing two complete and two partial genes. In this region, we found three major haplotypes that were designated as H1, H2 and H3. The H2 haplotype contributed the high-SNS allele in both H1 × H2 and H2 × H3 segregating populations. The ancestral H3 haplotype is frequent in wild emmer (48%) but rare (~ 1%) in cultivated wheats. By contrast, the H1 and H2 haplotypes became predominant in modern cultivated durum and common wheat, respectively. Among the four candidate genes, only TraesCS7A02G481600 showed a non-synonymous polymorphism that differentiated H2 from the other two haplotypes. This gene, designated here as WHEAT ORTHOLOG OF APO1 (WAPO1), is an ortholog of the rice gene ABERRANT PANICLE ORGANIZATION 1 (APO1), which affects spikelet number. Taken together, the high-resolution genetic map, the association between polymorphisms in the different mapping populations with differences in SNS, and the known role of orthologous genes in other grass species suggest that WAPO-A1 is the most likely candidate gene for the 7AL SNS QTL among the four genes identified in the candidate gene region
Methods for estimating the case fatality ratio for a novel, emerging infectious disease.
During the course of an epidemic of a potentially fatal disease, it is important that the case fatality ratio be well estimated. The authors propose a novel method for doing so based on the Kaplan-Meier survival procedure, jointly considering two outcomes (death and recovery), and evaluate its performance by using data from the 2003 epidemic of severe acute respiratory syndrome in Hong Kong, People's Republic of China. They compare this estimate obtained at various points in the epidemic with the case fatality ratio eventually observed; with two commonly quoted, naïve estimates derived from cumulative incidence and mortality statistics at single time points; and with estimates in which a parametric mixture model is used. They demonstrate the importance of patient characteristics regarding outcome by analyzing subgroups defined by age at admission to the hospital
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