Towards a muon scattering tomography system for both low-Z and high-Z materials

Muon scattering tomography (MST) is a non-destructive technique to image various materials by utilizing cosmic ray muons as probes. A typical MST system with a two-fold track detectors is particularly effective in detecting high-$Z$ materials (e.g. nuclear materials), but difficult to recognize low-$Z$ materials (e.g. explosive materials). In this work, we present a concept of MST system to discriminate both low-$Z$ and high-$Z$ materials by extra measuring momentum of low-energy muons with a Cherenkov detector. A toy Monte Carlo simulation to describe detector responses and multiple scatterings of a muon tracking through materials is developed for statistical tests. Based on momentum-dependent track reconstruction and image reconstruction algorithm, we evaluate separation powers of different materials in the system. The results show that momentum measurement of low-energy muons and accurate track reconstruction can improve separation power of low-$Z$ materials significantly. This may enable the MST system to detect both low-$Z$ and high-$Z$ materials with cosmic ray muons in the whole energy range.Comment: 17 pages with 13 figures and 1 tabl

Examining the density and diversity of human activity in the built environment: The case of the pearl river delta, China

Rapid urbanization in China has been accompanied by spatial inefficiency in patterns of human activity, of which 'ghost towns' are the most visible result. In this study, we measure the density and diversity of human activity in the built environment and relate this to various explanatory factors. Using the Pearl River Delta (PRD) as an empirical case, our research demonstrates the distribution of human activity by multi-source data and then explores its dynamics within these areas. This empirical study is comprised of two parts. The first part explores location information regarding human activity in urbanized areas and shows density and diversity. Regression models are applied to explore how density and diversity are affected by urban scale, morphology and by a city's administrative level. Results indicate that: 1) cities with smaller populations are more likely to be faced with lower density and diversity, but they derive greater marginal benefits from improving land use efficiency; 2) the compactness of the layout of urban land, an index reflecting the plane shapes of the built environment, is highly correlated with density and diversity in built-up areas; and 3) the administrative importance of a city has a significant and positive impact on the density of human activity, but no obvious influence on its diversity

Inhibition of Bone Morphogenetic Protein Signal Transduction Prevents the Medial Vascular Calcification Associated with Matrix Gla Protein Deficiency

Objective: Matrix Gla protein (MGP) is reported to inhibit bone morphogenetic protein (BMP) signal transduction. MGP deficiency is associated with medial calcification of the arterial wall, in a process that involves both osteogenic transdifferentiation of vascular smooth muscle cells (VSMCs) and mesenchymal transition of endothelial cells (EndMT). In this study, we investigated the contribution of BMP signal transduction to the medial calcification that develops in MGP-deficient mice. Approach and Results MGP-deficient mice (MGP-/-) were treated with one of two BMP signaling inhibitors, LDN-193189 or ALK3-Fc, beginning one day after birth. Aortic calcification was assessed in 28-day-old mice by measuring the uptake of a fluorescent bisphosphonate probe and by staining tissue sections with Alizarin red. Aortic calcification was 80% less in MGP-/- mice treated with LDN-193189 or ALK3-Fc compared with vehicle-treated control animals (P<0.001 for both). LDN-193189-treated MGP-/- mice survived longer than vehicle-treated MGP-/- mice. Levels of phosphorylated Smad1/5 and Id1 mRNA (markers of BMP signaling) did not differ in the aortas from MGP-/- and wild-type mice. Markers of EndMT and osteogenesis were increased in MGP-/- aortas, an effect that was prevented by LDN-193189. Calcification of isolated VSMCs was also inhibited by LDN-193189. Conclusions: Inhibition of BMP signaling leads to reduced vascular calcification and improved survival in MGP-/- mice. The EndMT and osteogenic transdifferentiation associated with MGP deficiency is dependent upon BMP signaling. These results suggest that BMP signal transduction has critical roles in the development of vascular calcification in MGP-deficient mice

A Mechanics Study on the Self-Righting of Abalone from the Substrate

In this study, we aim to probe the self-righting behavior of abalone on a substrate based on experiments and mechanistic analyses. A successful self-righting process of abalone is observed, and its critical condition in theory can be given in terms of the rotation angle. Then, according to the moment balance and potential energy minimization, the required tension force of the abalone foot for self-righting is derived with respect to the rotation angle. The experimental result also shows that in many cases the abalone cannot finish this self-righting process. Then, measurements on the tolerant strength of abalone muscle and tolerant adhesion strength of the foot on substrate are both conducted. It is judged that the abalone muscle is strong enough, which can provide enough tension force, and thus, the self-righting mainly depends on the adhesion area of the foot on substrate. These findings cast new light on engineering new types of biomaterials and devices, such as marine equipment and soft robotics

The Analysis of a Novel Computational Thinking Test in a First Year Undergraduate Computer Science Course

In Ireland, Computer Science is not yet a state examination subject. In recent years, steps to include it have been taken - it was introduced as a Leaving Certificate subject in the academic year of 2018-19 on a pilot basis and will be examined for the first time in 2020 (O’Brien, 2017). Prior to this, the only Computer Science course offered at second level was a Junior Certificate Coding short course (NCCA, 2017). Research shows that an early introduction to computing is an advantage for students. It can build confidence in dealing with complexity and with open-ended problems (Yevseyeva &Towhidnejad, 2012). Problem-solving skills can be extended and transferred as reported by Koh et al. (2013) and students’ analytical skills can be improved according to Lishinski et al. (2016) and Van Dyne and Braun (2014). It has been shown by Webb and Rosson (2013) that students’ self-efficacy for computational problem solving, abstraction, debugging and terminology can be in-creased. It has also been found that teaching Computational Thinking can provide a better understanding of how programming is about solving a problem (not just coding) and that it can improve female students’ attitudes and confidence towards programming (Davies, 2008). One especially interesting finding is that exposure to Computational Thinking can be used as an early indicator and predictor of academic success since Computational Thinking scores have been found to correlate strongly with general academic achievement by Haddad and Kalaani (2015). This paper examines first year undergraduate Computer Science students who took a novel test to assess their Computational Thinking skills and in addition a survey gathering their views on Computer Science and Computational Thinking. This survey was administered twice within the academic year and comparisons are drawn on the changes between these survey results

A. Delineation of the smallest portion of Ge-1 that mediates interaction with LMKB.

<p>GFP-NLS-Ge-1 fragment (amino acids 630–1437) localized to nuclear dots (green, ii) in HEp-2 cells, but RFP-LMKB remained in P-bodies and was not detected in the nucleus (red, i), suggesting that N-terminal amino acids in Ge-1 are required for interaction with LMKB. To identify the N-terminal portion of Ge-1 that interacts with LMKB, RFP-LMKB was tested for the ability to recruit N-terminal fragments of Ge-1 to P-bodies. In the presence of RFP-LMKB (red, iv), GFP-Ge-1(1–1094) localized to cytoplasmic dots resembling P-bodies (green, v). In cells expressing RFP-LMKB (red, vii) and GFP-Ge-1(1–1094) (green, viii), both proteins co-localized with endogenous Ge-1 (blue, ix), confirming that these structures are P-bodies. In the absence of LMKB (RFP alone, red, x), GFP-Ge-1(1–1094) did not localize to P-bodies (green, xi), but was instead distributed throughout the cytoplasm. Smaller fragments of Ge-1, including amino acids 1–935 (green, xiv) and 104–1094 (green, xvii) did not co-localize with co-expressed LMKB in P-bodies. Merge of fluorescence in i and ii, iv and v, x and xi, xiii and xiv, and xvi and xvii is shown in iii, vi, xii, xv and xviii. DAPI staining (blue in the merged panels) indicates the location of nuclei. White bar in xviii indicates 5.0 µm. <b>B.</b> Schematic representation of Ge-1 and summary of results. The N-terminus of Ge-1 contains a WD40 repeat domain. The C-terminus contains four regions that have repeating hydrophobic residue periodicity (ψ(X_2-3)-repeat domains). + indicates a fragment of Ge-1 that interacts with LMKB; - indicates a fragment of Ge-1 that does not interact with LMKB. The black rectangle indicates the smallest tested portion of Ge-1 that interacts with LMKB.</p

Loss of LMKB immunoreactivity after LMKB knockdown in BJAB and Hut78 cells.

<p>Treatment of BJAB cells with siRNA directed against LMKB resulted in loss of P-body staining as determined by indirect immunofluorescence (i). LMKB was detected in a cytoplasmic dot staining pattern in cells treated with control siRNA (green, iv). DAPI staining (blue) in ii and v indicate the location of nuclei. Merge of the preceding panels is shown in iii and vi. Treatment of Hut78 cells with siRNA directed against LMKB also resulted in loss of cytoplasmic dot staining (vii), compared with cells treated with control siRNA (green, x). Loss of LMKB did not alter the cellular location of Ge-1-containing P-bodies (red, viii and xi) demonstrating that LMKB is not required for P-body formation. Merge of vii and viii, and x and xi, is shown in ix and xii. DAPI staining (blue) in the merged panels indicates the location of nuclei. White bar in xii indicates 5.0 µm.</p

The effects of LMKB depletion on gene expression in BJAB and Hut78 cells

<p>. SiRNA-mediated knock-down of LMKB in BJAB and Hut78 cells resulted in a greater than 80% decrease in the level of <i>LMKB</i> mRNA (i). LMKB depletion had no effect on the level of <i>PPP2cb</i> mRNA in either cell line (ii). The level of <i>IFI44L</i> mRNA was increased in both BJAB and Hut78 cell lines after LMKB knock-down (iii).</p