High-speed, high-frequency ultrasound, \u3ci\u3ein utero\u3c/i\u3e vector-flow imaging of mouse embryos

Real-time imaging of the embryonic murine cardiovascular system is challenging due to the small size of the mouse embryo and rapid heart rate. High-frequency, linear-array ultrasound systems designed for small-animal imaging provide high-frame-rate and Doppler modes but are limited in regards to the field of view that can be imaged at fine-temporal and -spatial resolution. Here, a plane-wave imaging method was used to obtain high-speed image data from in utero mouse embryos and multi-angle, vector-flow algorithms were applied to the data to provide information on blood flow patterns in major organs. An 18-MHz linear array was used to acquire plane-wave data at absolute frame rates ≥10 kHz using a set of fixed transmission angles. After beamforming, vector-flow processing and image compounding, effective frame rates were on the order of 2 kHz. Data were acquired from the embryonic liver, heart and umbilical cord. Vector-flow results clearly revealed the complex nature of blood-flow patterns in the embryo with fine-temporal and -spatial resolution

Searching for a signal: Environmental DNA (eDNA) for the detection of invasive signal crayfish, Pacifastacus leniusculus (Dana, 1852)

Environmental DNA (eDNA) is a rapid, non-invasive method for species detection and distribution using DNA deposited in the environment by target organisms. eDNA has become a recognised and powerful tool for detecting invasive species in a broad range of aquatic ecosystems. We examined the use of eDNA as a tool for detecting the invasive American signal crayfish Pacifastacus leniusculus in Scotland. Species-specific TaqMan probe and primers were designed for P. leniusculus and a robust quantitative PCR (qPCR) assay and DNA extraction protocol were developed. We investigated the detection capability for P. leniusculus from water samples in a controlled laboratory experiment and determined whether crayfish density (low = 1 crayfish 5.5 L-1 or high = 3 crayfish 5.5 L-1) or length of time in tanks (samples taken at 1, 3 and 7 days) influenced DNA detectability. Additionally, the persistence of DNA was investigated after P. leniusculus removal (samples taken at 1, 3 and 7 days post removal). P. leniusculus DNA was consistently detected during the entire 7-day period and higher density tanks yielded stronger positive results with lower Ct values. After removal of P. leniusculus, there was a rapid and continuous decrease in the detectability of DNA. P. leniusculus DNA could only be detected in high density tanks by the end of the 7-day period, while DNA was no longer detectable in low density tanks after 72 hours. Preliminary field experiments sampled water from three sites in winter and five sites in summer. P. leniusculus was known to be present at two of these sites. P. leniusculus was not detected at any site in winter. However, in summer, positive signals were observed at sites with known P. leniusculus, and at sites where P. leniusculus was believed to be present anecdotally, but not confirmed. All sites where crayfish were believed to be absent were negative for eDNA. Therefore, eDNA represents a promising technique to detect and monitor invasive P. leniusculus, although the presence of detectable amounts of eDNA may be season and location dependent, even where invasive crayfish are known to be present

Changes in everyday mobility in England since the 1940s: A case study

Everyday mobility is usually neglected in academic studies of population movement. This paper argues that it deserves greater attention, and that interaction between everyday mobility and residential migration is increasingly significant. Data on changes in everyday mobility since the 1940s have been collected through a series of surveys and in-depth interviews. This paper presents results from a case study of the everyday mobility of children aged 10/11 in Lancaster, NW England. Analysis of changes in the distance travelled, the time spent travelling, the mode of transport used and of travel companions shows that although there have been major and obvious changes in transport technology, and in the structure of economy and society, since the 1940s, many aspects of everyday mobility did not change. For many everyday activities the distances over which children travel have changed little, the time taken in travelling for everyday mobility has changed less, and gender differentials in both the mode of transport used and travel companions are stable over time. The most significant change is the restrictive influence of the fear of crime.La mobilité quotidienne est généralement négligée dans les études universitaires du mouvement de la population. Cet article affirme qu’elle mérite plus d’attention, et que l’interaction entre mobilité quotidienne et migration résidentielle est de plus en plus significative. Les données concernant l’évolution de la mobilité quotidienne depuis les années quarante ont été rassemblées au moyen d’une série de sondages et d’entrevues en profondeur. Cet article présente les résultats d’une étude de cas de la mobilité quotidienne des enfants de dix à onze ans à Lancaster, au nord-ouest de l’Angleterre. L’analyse des changements en termes de distance parcourue, de durée, de moyen de transport utilisé et de compagnons de voyage, démontre qu’en dépit d’évidentes et significatives modifications dans la technologie des transports et la structure de l’économie et de la société depuis les années quarante, un grand nombre d’aspects de la mobilité quotidienne n’ont pas évolué. Pour beaucoup d’activités quotidiennes, les distances parcourues par les enfants ont peu changé, le temps qu’ils y consacrent encore moins, et les différences entre hommes et femmes, non seulement en ce qui concerne le mode de transport utilisé, mais aussi par rapport aux compagnons de voyage, sont restées stables au cours du temps. Le changement le plus significatif est l’influence restrictive de la peur du crime

Regulation of Carotenoid Composition and Shoot Branching in Arabidopsis by a Chromatin Modifying Histone Methyltransferase, SDG8

Carotenoid pigments are critical for plant survival, and carotenoid composition is tuned to the developmental stage, tissue, and to environmental stimuli. We report the cloning of the CAROTENOID CHLOROPLAST REGULATORY1 (CCR1) gene. The ccr1 mutant has increased shoot branching and altered carotenoid composition, namely, reduced lutein in leaves and accumulation of cis-carotenes in dark-grown seedlings. The CCR1 gene was previously isolated as EARLY FLOWERING IN SHORT DAYS and encodes a histone methyltransferase (SET DOMAIN GROUP 8) that methylates histone H3 on Lys 4 and/or 36 (H3K4 and H3K36). ccr1 plants show reduced trimethyl-H3K4 and increased dimethyl-H3K4 surrounding the CAROTENOID ISOMERASE (CRTISO) translation start site, which correlates with low levels of CRTISO mRNA. Microarrays of ccr1 revealed the downregulation of 85 genes, including CRTISO and genes associated with signaling and development, and upregulation of just 28 genes. The reduction in CRTISO transcript abundance explains the altered carotenoid profile. The changes in shoot branching are additive with more axillary branching mutants, but the altered carotenoid profile may partially affect shoot branching, potentially by perturbed biosynthesis of the carotenoid substrates of strigolactones. These results are consistent with SDG8 regulating shoot meristem activity and carotenoid biosynthesis by modifying the chromatin surrounding key genes, including CRTISO. Thus, the level of lutein, the most abundant carotenoid in higher plants that is critical for photosynthesis and photoprotection, appears to be regulated by a chromatin modifying enzyme in Arabidopsis thaliana

High-frequency ultrasonic speckle velocimetry in sheared complex fluids

High-frequency ultrasonic pulses at 36 MHz are used to measure velocity profiles in a complex fluid sheared in the Couette geometry. Our technique is based on time-domain cross-correlation of ultrasonic speckle signals backscattered by the moving medium. Post-processing of acoustic data allows us to record a velocity profile in 0.02--2 s with a spatial resolution of 40 $\mu$m over 1 mm. After a careful calibration using a Newtonian suspension, the technique is applied to a sheared lyotropic lamellar phase seeded with polystyrene spheres of diameter 3--10 $\mu$m. Time-averaged velocity profiles reveal the existence of inhomogeneous flows, with both wall slip and shear bands, in the vicinity of a shear-induced ``layering'' transition. Slow transient regimes and/or temporal fluctuations can also be resolved and exhibit complex spatio-temporal flow behaviors with sometimes more than two shear bands.Comment: 15 pages, 18 figures, submitted to Eur. Phys. J. A

Taming Labor: Workers’ struggles, workplace unionism and collective bargaining on a Chinese waterfront

This paper draws on data acquired in semi-structured interviews to address the question of effective workplace trade unionism in China. These are rarely-sighted phenomena due to rigid prohibitions on organizing outside the Party-led All-China Federation of Trade Unions. Indeed some commentators are extinct. Evidence from a case study of the Yantian International Container Terminal suggests that this is not necessarily the case. The authors do not underestimate the very real constraints on labor organizing but rather turn the spotlight on working class power in the wider context of labor militancy and cautious trade union reform. We argue that the YICT union developed a system of annual collective bargaining in order to ‘tame’ the power of militant dockworkers and prevent strikes. This required an effective enterprise-level trade union that was nevertheless able to manipulate members’ somewhat ambiguous acceptance of its role