Optimal target search on a fast folding polymer chain with volume exchange

We study the search process of a target on a rapidly folding polymer (`DNA') by an ensemble of particles (`proteins'), whose search combines 1D diffusion along the chain, Levy type diffusion mediated by chain looping, and volume exchange. A rich behavior of the search process is obtained with respect to the physical parameters, in particular, for the optimal search.Comment: 4 pages, 3 figures, REVTe

Case Study: Visitor Perceptions of Captive Wildlife Tourism in a Western Australian Natural Setting

Wildlife tourism involves a broad sweep of experiences that includes all of the aspects of the tourism genre with the distinguishing feature of animals as the primary attraction. The uniqueness of Australian wildlife in combination with factors such as remoteness and rarity appear to have provided the ideal context for successful wildlife tourism operations. Barna Mia, located in a large remnant woodland in the central southern wheatbelt of Western Australia, is approximately 165 km southeast of the state's capital, Perth. Dryandra Woodland, the location of Barna Mia, consists of a closely grouped and connected cluster of native remnant vegetation blocks. The enclosure is surrounded by electrified, vermin proof fencing to keep feral predators out and the captive fauna in. The results of the visitor survey at Barna Mia suggested the experience provided a great sense of satisfaction amongst respondents. This was both in terms of the overall satisfaction as well as satisfaction with specific parts of the experience. The feeling of being "in the wild" may have been enhanced by the lack of barriers between visitors and the animals and the absence of constraints on animal movement through the enclosure. Improving the operation of Barna Mia as an attraction in itself and as part of the Dryandra Woodland product may serve to improve its success as an attraction. However, an innately attractive tourism experience cannot work without appropriate integration within the specific wildlife tourism product of Dryandra Woodland, while coordination with tourism on a regional scale is also important

Automatic motion compensation for structured illumination endomicroscopy using a flexible fiber bundle

Significance: Confocal laser scanning enables optical sectioning in clinical fiber bundle endomicroscopes, but lower-cost, simplified endomicroscopes use widefield incoherent illumination instead. Optical sectioning can be introduced in these simple systems using structured illumination microscopy (SIM), a multiframe digital subtraction process. However, SIM results in artifacts when the probe is in motion, making the technique difficult to use in vivo and preventing the use of mosaicking to synthesize a larger effective field of view (FOV). Aim: We report and validate an automatic motion compensation technique to overcome motion artifacts and allow generation of mosaics in SIM endomicroscopy. Approach: Motion compensation is achieved using image registration and real-time pattern orientation correction via a digital micromirror device. We quantify the similarity of moving probe reconstructions to those acquired with a stationary probe using the relative mean of the absolute differences (MAD). We further demonstrate mosaicking with a moving probe in mechanical and freehand operation. Results: Reconstructed SIM images show an improvement in the MAD from 0.85 to 0.13 for lens paper and from 0.27 to 0.12 for bovine tissue. Mosaics also show vastly reduced artifacts. Conclusion: The reduction in motion artifacts in individual SIM reconstructions leads to mosaics that more faithfully represent the morphology of tissue, giving clinicians a larger effective FOV than the probe itself can provide

Reconciling diverse lacustrine and terrestrial system response to penultimate deglacial warming in southern Europe

Unlike the most recent deglaciation, the regional expression of climate changes during the penultimate deglaciation remains understudied, even though it led into a period of excess warmth with estimates of global average temperature 1–2 °C, and sea level ∼6 m, above pre-industrial values. We present the first complete high-resolution southern European diatom record capturing the penultimate glacial-interglacial transition, from Lake Ioannina (northwest Greece). It forms part of a suite of proxies selected to assess the character and phase relationships of terrestrial and aquatic ecosystem response to rapid climate warming, and to resolve apparent conflicts in proxy evidence for regional paleohydrology. The diatom data suggest a complex penultimate deglaciation driven primarily by multiple oscillations in lake level, and provide firm evidence for the regional influence of abrupt changes in North Atlantic conditions. There is diachroneity in lake and terrestrial ecosystem response to warming at the onset of the last interglacial, with an abrupt increase in lake level occurring ∼2.7 k.y. prior to sustained forest expansion with peak precipitation. We identify the potentially important role of direct input of snow melt and glacial meltwater transfer to the subterranean karst system in response to warming, which would cause rising regional groundwater levels. This explanation, and the greater sensitivity of diatoms to subtle changes in temperature, reconciles the divergent lacustrine and terrestrial proxy evidence and highlights the sensitivity of lakes situated in mountainous karstic environments to past climate warming

Preconditioning and triggering of offshore slope failures and turbidity currents revealed by most detailed monitoring yet at a fjord-head delta

Rivers and turbidity currents are the two most important sediment transport processes by volume on Earth. Various hypotheses have been proposed for triggering of turbidity currents offshore from river mouths, including direct plunging of river discharge, delta mouth bar flushing or slope failure caused by low tides and gas expansion, earthquakes and rapid sedimentation. During 2011, 106 turbidity currents were monitored at Squamish Delta, British Columbia. This enables statistical analysis of timing, frequency and triggers. The largest peaks in river discharge did not create hyperpycnal flows. Instead, delayed delta-lip failures occurred 8–11 h after flood peaks, due to cumulative delta top sedimentation and tidally-induced pore pressure changes. Elevated river discharge is thus a significant control on the timing and rate of turbidity currents but not directly due to plunging river water. Elevated river discharge and focusing of river discharge at low tides cause increased sediment transport across the delta-lip, which is the most significant of all controls on flow timing in this setting

An Overview of Technology Investments in the NASA Entry Systems Modeling Project

ESM was created with two primary technical areas: Aerosciences and Materials. One of the first project deliverables, in both technology areas, was the development of Key Performance Parameters (KPPs), which are used to gauge the rate of progress in technology maturation, and to inform eventual technology downselects. In addition, the project was tasked to identify stakeholders or customers for proposed technology investments. While pull technologies are permitted within STMD, those capabilities that have strong customer support and a clear infusion plan are given higher priority. The current investment portfolio and achievements will be summarized in this paper

Modal quantum theory

We present a discrete model theory similar in structure to ordinary quantum mechanics, but based on a finite field instead of complex amplitudes. The interpretation of this theory involves only the "modal" concepts of possibility and necessity rather than quantitative probability measures. Despite its simplicity, our model theory includes entangled states and has versions of both Bell's theorem and the no cloning theorem.Comment: Presented at the 7th Workshop on Quantum Physics and Logic, Oxford University (29-30 May 2010). Revised 1 Aug 2011 in response to referee comment

Within- and Between-Child Variation in Repeated Urinary Pesticide Metabolite Measurements over a 1-Year Period

Background: Children are exposed to pesticides from many sources and routes, including dietary and incidental ingestion, dermal absorption, and inhalation. Linking health outcomes to these exposures using urinary metabolites requires understanding temporal variability within subjects to avoid exposure misclassification. Objectives: We characterized the within- and between-child variability of urinary organophosphorus and pyrethroid metabolites in 23 participants of the Children’s Pesticide Exposure Study–Washington over 1 year and examined the ability of one to four spot urine samples to categorize mean exposures. Methods: Each child provided urine samples twice daily over 7- to 16-day sessions in four seasons in 2003 and 2004. Samples were analyzed for five pyrethroid and five organophosphorus (OP) metabolites. After adjusting for specific gravity, we used a customized maximum likelihood estimation linear mixed-effects model that accounted for values below the limit of detection to calculate intraclass correlation coefficients (ICC) and conducted surrogate category analyses. Results: Within-child variability was 2–11 times greater than between-child variability. When restricted to samples collected during a single season, ICCs were higher in the fall, winter, and spring than in summer for OPs, and higher in summer and winter for pyrethroids, indicating an increase in between-person variability relative to within-person variability during these seasons. Surrogate category analyses demonstrated that a single spot urine sample did not categorize metabolite concentrations well, and that four or more samples would be needed to categorize children into quartiles consistently. Conclusions: Urinary biomarkers of these short half-life pesticides exhibited substantial within-person variability in children observed over four seasons. Researchers investigating pesticides and health outcomes in children may need repeated biomarker measurements to derive accurate estimates of exposure and relative risks. Citation: Attfield KR, Hughes MD, Spengler JD, Lu C. 2014. Within- and between-child variation in repeated urinary pesticide metabolite measurements over a 1-year period. Environ Health Perspect 122:201–206; http://dx.doi.org/10.1289/ehp.130673

Evaluation of a postdischarge coronary artery disease management program

ObjectivesWe conducted a demonstration project to assess the value of a nurse practitioner (NP) based coronary artery disease management (CAD‐DM) program for patients with an acute coronary syndrome (ACS) or percutaneous coronary intervention.MethodsPatients were recruited to attend three 1‐h monthly visits. The intervention included assessment of clinical symptoms and guideline‐based treatments; education regarding CAD/ACS; review of nutrition, exercise, and appropriate referrals; and recognition of significant symptoms and emergency response.ResultsTwo hundred thirteen (84.5%) completed the program. Physician approval for patient participation was 99%. Average age was 63 ± 11 years, 70% were male, and 89% white. At baseline, 61% (n = 133) had one or more cardiopulmonary symptoms, which declined to 30% at 12 weeks, p < .001. Sixty‐nine percent attended cardiac rehabilitation or an exercise consult. Compared to the initial assessment, an additional 20% were at low‐density lipoprotein cholesterol < 70 mg/dL (p = .04), an additional 35% met exercise goals (p < .0001), and there was an improvement in the mental (baseline 49.7 vs. 12 weeks 53, p = .0015) and physical components (44 vs. 48, p = .002) of the SF‐12 health survey.ConclusionThis NP‐based CAD‐DM program was well received and participants demonstrated improvement in physical and mental health, and increased compliance with recommended lifestyle changes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112261/1/jaan12201.pd

Human Performance on Visually Presented Traveling Salesperson Problems with Varying Numbers of Nodes

We investigated the properties of the distribution of human solution times for Traveling Salesperson Problems (TSPs) with increasing numbers of nodes. New experimental data are presented that measure solution times for carefully chosen representative problems with 10, 20, . . . 120 nodes. We compared the solution times predicted by the convex hull procedure proposed by MacGregor and Ormerod (1996), the hierarchical approach of Graham, Joshi, and Pizlo (2000), and by five algorithms drawn from the artificial intelligence and operations research literature. The most likely polynomial model for describing the relationship between mean solution time and the size of a TSP is linear or near-linear over the range of problem sizes tested, supporting the earlier finding of Graham et al. (2000). We argue the properties of the solution time distributions place strong constraints on the development of detailed models of human performance for TSPs, and provide some evaluation of previously proposed models in light of our findings