Neutron Electromagnetic Form Factors

The nucleon electromagnetic form factors have been studied in the past extensively from unpolarized electron scattering experiments. With the development in polarized beam, recoil polarimetry, and polarized target technologies, polarization experiments have provided more precise data on these quantities. In this talk, I review recent experimental progress on this subject.Comment: 7 pages, 3 figures, Plenary talk presented at the 10th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon, August 29 - September 4, 2004, Beijing, Chin

SenVis: Interactive Tensor-based Sensitivity Visualization

Sobol's method is one of the most powerful and widely used frameworks for global sensitivity analysis, and it maps every possible combination of input variables to an associated Sobol index. However, these indices are often challenging to analyze in depth, due in part to the lack of suitable, flexible enough, and fast-to-query data access structures as well as visualization techniques. We propose a visualization tool that leverages tensor decomposition, a compressed data format that can quickly and approximately answer sophisticated queries over exponential-sized sets of Sobol indices. This way, we are able to capture the complete global sensitivity information of high-dimensional scalar models. Our application is based on a three-stage visualization, to which variables to be analyzed can be added or removed interactively. It includes a novel hourglass-like diagram presenting the relative importance for any single variable or combination of input variables with respect to any composition of the rest of the input variables. We showcase our visualization with a range of example models, whereby we demonstrate the high expressive power and analytical capability made possible with the proposed method

Driving Cell Seeding Using Surface Acoustic Wave Fluid Actuation

In this paper, we investigate the ability to drive fluid streaming via a surface acoustic wave (SAW) into a porous bioscaffold structure, and to exploit this effect to deliver fluorescent particles/yeast cells into the scaffold as a potential rapid and efficient method for cell seeding in tissue engineering. The results demonstrate that the seeding process takes approximately 10 seconds, much shorter than that if the cell suspension were to perfuse through the scaffold under the effects of gravity alone (approximately 30 mins). By increasing the input power, both the velocity of the fluid flow and the particle seeding efficiency can be enhanced. At 560 mW, fluid velocities of the order 10 mm/s were achieved; in this case, the particle/yeast seeding efficiency is around 92%. In addition to rapid seeding, the SAW streaming induced perfusion is observed to significantly improve the uniformity of the scaffold cell distribution due to greater penetration into the scaffold. Finally, we verify using a methylene violet staining procedure that 80% of the yeast cells seeded by the SAW method within the scaffold remained viable

Impact of temperatures on Hessian fly (Diptera: Cecidomyiidae) resistance in selected wheat cultivars (Poales: Poaceae) in the Great Plains region

Citation: Chen, Ming-Shun, Shanda Wheeler, Haiyan Wang, and R. Jeffrey Whitworth. 2014. “Impact of Temperatures on Hessian Fly (Diptera: Cecidomyiidae) Resistance in Selected Wheat Cultivars (Poales: Poaceae) in the Great Plains Region.” Journal of Economic Entomology 107 (3): 1266–73. https://doi.org/10.1603/EC13357.Changes in temperature can result in fundamental changes in plant physiology. This study investigated the impact of different temperatures from 14 to 26°C on the resistance or susceptibility to the Hessian fly, Mayetiola destructor (Say), of selected wheat cultivars that are either currently popular in the Great Plains area or soon to be released to this region. We found that many wheat cultivars including ‘Bill Brown,’ ‘Byrd,’ ‘Endurance,’ ‘Fuller,’ ‘GA-031257-10LE34,’ and ‘KS09H19-2-3’ were susceptible to Hessian fly infestation at ≥20°C, but became resistant at a certain lower temperature, depending on different cultivars. These cultivars were classified as Hessian fly susceptible according to the traditional standards, and their impact on Hessian fly management needs to be reevaluated. However, many wheat cultivars that were resistant at ≤20°C became destabilized at a certain higher temperature. Phenotypic variations among the resistant cultivars at different temperatures were also observed, suggesting potential different resistance mechanisms. Studies on the genetic and molecular mechanisms associated with resistance at different temperatures are needed, which may lead to improved wheat cultivars with more durable resistance to Hessian fly infestation

Tensor Approximation for Multidimensional and Multivariate Data

Tensor decomposition methods and multilinear algebra are powerful tools to cope with challenges around multidimensional and multivariate data in computer graphics, image processing and data visualization, in particular with respect to compact representation and processing of increasingly large-scale data sets. Initially proposed as an extension of the concept of matrix rank for 3 and more dimensions, tensor decomposition methods have found applications in a remarkably wide range of disciplines. We briefly review the main concepts of tensor decompositions and their application to multidimensional visual data. Furthermore, we will include a first outlook on porting these techniques to multivariate data such as vector and tensor fields

Complexity of downy birch emissions revealed by Vocus proton transfer reaction time-of-flight mass spectrometer

Biogenic volatile organic compounds (BVOCs) are known to strongly influence the global climate by affecting various atmospheric constituents such as oxidants and aerosols. Among the several BVOCs that are emitted continuously into the atmosphere, studies have shown that up to 96% of the emissions have been missed out by current analytical techniques. In this study, we used a Vocus proton-transfer-reaction time-of-flight mass spectrometer (Vocus) to characterize and quantify emissions from a branch of a downy birch tree at a boreal forest site in Hyytiala, Finland in August 2019. During the measurement period, we were able to observe real-time emissions of hydrocarbons with up to 20 carbon atoms and oxygenated compounds (OVOCs) with up to 4 oxygen atoms. OVOCs accounted for around 90% of the total observed emissions with the largest contribution from C8H8O3 (0.37 mu gg(-1)h(-1); similar to 60% of total). For the first time, emissions of diterpenes (C20H32, C20H36, and C20H38) were observed from downy birch tree, although in minor quantities (0.1% of total emissions). During this late growing season, C10H16 and C10H14 contributed similar to 7% in total emissions, while the sum of C5H8, C15H22, and C15H24 contributed around similar to 3%. The branch experienced abiotic stress during the measurement period, which might explain the unusually high emissions of C8H8O3. Standardized emission potentials are reported for all compounds using two Guenther algorithms. While emissions of most compounds fit well with either of the two algorithms, emissions of certain compounds like C8H8O3 could not be explained by either suggesting the influence of other factors besides temperature and light. Vocus PTR-TOF-MS can help identify a diverse range of molecules even if emitted in minute quantities. The BVOCs detected from birch emissions may be important in the formation of secondary organic aerosols but their implications in the atmosphere need to be verified with further studies.Peer reviewe

Exotic Hadrons Of Minimal Pentaquark (qqqq\Bar{Q}) States

It is shown that the exotic non-qqq hadrons of pentaquark $qqqq\bar{q}$ states can be clearly distinguished from the conventional qqq-baryon resonances or their hybrids if the flavor of $\bar{q}$ is different from any of the other four quarks. We suggest the physical process $p(e,e'K^-)Z(uuud\bar{s})$, which can be investigated at the Thomas Jefferson National Accelerator Facility (JLab), as an ideal process to search for the existence or non-existence of the exotic hadron of minimal pentaquark state $Z(uuud\bar{s})$. (The search for the existence of $Z(uudd\bar{s})$ is also discussed in the paper. We added this sentence after the original published form of this paper.)Comment: 7 latex pages, 1 figur

Subsampling Methods for Genomic Inference

Large-scale statistical analysis of data sets associated with genome sequences plays an important role in modern biology. A key component of such statistical analyses is the computation of p-values and confidence bounds for statistics defined on the genome. Currently such computation is commonly achieved through ad hoc simulation measures. The method of randomization, which is at the heart of these simulation procedures, can significantly affect the resulting statistical conclusions. Most simulation schemes introduce a variety of hidden assumptions regarding the nature of the randomness in the data, resulting in a failure to capture biologically meaningful relationships. To address the need for a method of assessing the significance of observations within large scale genomic studies, where there often exists a complex dependency structure between observations, we propose a unified solution built upon a data subsampling approach. We propose a piecewise stationary model for genome sequences and show that the subsampling approach gives correct answers under this model. We illustrate the method on three simulation studies and two real data examples

Massive Shift in Gene Expression during Transitions between Developmental Stages of the Gall Midge, Mayetiola Destructor

Citation: Chen, M. S., Liu, S. Z., Wang, H. Y., Cheng, X. Y., El Bouhssini, M., & Whitworth, R. J. (2016). Massive Shift in Gene Expression during Transitions between Developmental Stages of the Gall Midge, Mayetiola Destructor. PLoS One, 11(5), 1-19. https://doi.org/10.1371/journal.pone.0155616Mayetiola destructor is a destructive pest of wheat and has six developmental stages. Molecular mechanisms controlling the transition between developmental stages remain unknown. Here we analyzed genes that were expressed differentially between two successive developmental stages, including larvae at 1, 3, 5, and 7 days, pupae, and adults. A total of 17,344 genes were expressed during one or more of these studied stages. Among the expressed genes, 38-68% were differently expressed between two successive stages, with roughly equal percentages of up-and down-regulated genes. Analysis of the functions of the differentially expressed genes revealed that each developmental stage had some unique types of expressed genes that are characteristic of the physiology at that stage. This is the first genome-wide analysis of genes differentially expressed in different stages in a gall midge. The large dataset of up-and down-regulated genes in each stage of the insect shall be very useful for future research to elucidate mechanisms regulating insect development and other biological processes