Sketching: A Process of Drawing

The sketch is one of the most personal creations we make as students of architecture

Micrococcal Nuclease Does Not Substantially Bias Nucleosome Mapping

We have mapped sequence-directed nucleosome positioning on genomic DNA molecules using high-throughput sequencing. Chromatins, prepared by reconstitution with either chicken or frog histones, were separately digested to mononucleosomes using either micrococcal nuclease (MNase) or caspase-activated DNase (CAD). Both enzymes preferentially cleave internucleosomal (linker) DNA, although they do so by markedly different mechanisms. MNase has hitherto been very widely used to map nucleosomes, although concerns have been raised over its potential to introduce bias. Having identified the locations and quantified the strength of both the chicken or frog histone octamer binding sites on each DNA, the results obtained with the two enzymes were compared using a variety of criteria. Both enzymes displayed sequence specificity in their preferred cleavage sites, although the nature of this selectivity was distinct for the two enzymes. In addition, nucleosomes produced by CAD nuclease are 8–10 bp longer than those produced with MNase, with the CAD cleavage sites tending to be 4–5 bp further out from the nucleosomal dyad than the corresponding MNase cleavage sites. Despite these notable differences in cleavage behaviour, the two nucleases identified essentially equivalent patterns of nucleosome positioning sites on each of the DNAs tested, an observation that was independent of the histone type. These results indicate that biases in nucleosome positioning data collected using MNase are, under our conditions, not significant

Environmental and Genetic (vgll3) Effects on the Prevalence of Male Maturation Phenotypes in Domesticated Atlantic Salmon

Pre-harvest male maturation is problematic for Atlantic salmon (Salmo salar) farmers and is regulated by the environment and genetics (e.g., vgll3). Five families of all-male salmon parr (produced using YY males crossed with XX females) with different vgll3 genotypes were split between three environmental regimes in January 2018. The “advanced maturation” regime used elevated temperature (16 °C) and continuous light from January 2018 with post-smolt maturation assessed in March 2018. The “extended freshwater” regime used ambient freshwater (1–16 °C) and simulated natural photoperiod (SNP) with post-smolt maturation assessed in November 2018. The “sea transfer” regime used ambient temperatures (1–14 °C) and SNP in freshwater until May 2018 when they were transferred to 9 °C seawater with natural photoperiod for 2.5 years (final mean weight of circa. 14 kg) and assessed for post-smolt maturation, 1 sea-winter (1 SW) maturation, and 2 sea-winter (2 SW) maturation in the autumn (November/December) of 2018, 2019, and 2020, respectively. Post-smolt maturation was highest in the advanced maturation and extended freshwater regimes (39–99% depending on family) and lowest in the sea transfer regime (0–95% depending on family). In the sea transfer regime, maturity incidence increased over time (0–95% post-smolt maturation, 1–100% 1 SW, and 50–90% 2 SW maturation, depending on family). In all regimes, those homozygous for the pre-designated vgll3 “early” maturing allele had the highest incidences of maturation whilst those homozygous for the “late” allele had the lowest. A low percentage of 2 SW phenotypic and genetic females were found (0–5% depending on family), one of which was successfully crossed with an XY male resulting in progeny with an approx. 50/50 sex ratio. These results show (i) post-smolt maturation varies dramatically depending on environment although genetic regulation by vgll3 was as expected, and (ii) crossing YY sperm with XX eggs can result in XX progeny which can themselves produce viable progeny with an equal sex ratio when crossed with an XY male.publishedVersio

Vertebral deformities in interspecific diploid and triploid salmonid hybrids

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Spectroscopy and thermal modelling of the first interstellar object 1I/2017 U1 ‘Oumuamua

During the formation and evolution of the Solar System, significant numbers of cometary and asteroidal bodies were ejected into interstellar space. It is reasonable to expect that the same happened for planetary systems other than our own. Detection of such interstellar objects would allow us to probe the planetesimal formation processes around other stars, possibly together with the effects of long-term exposure to the interstellar medium. 1I/2017 U1 ‘Oumuamua is the first known interstellar object, discovered by the Pan-STARRS1 telescope in October 2017. The discovery epoch photometry implies a highly elongated body with radii of ~ 200 × 20 m when a comet-like geometric albedo of 0.04 is assumed. The observable interstellar object population is expected to be dominated by comet-like bodies in agreement with our spectra, yet the reported inactivity of 'Oumuamua implies a lack of surface ice. Here, we report spectroscopic characterization of ‘Oumuamua, finding it to be variable with time but similar to organically rich surfaces found in the outer Solar System. We show that this is consistent with predictions of an insulating mantle produced by long-term cosmic ray exposure. An internal icy composition cannot therefore be ruled out by the lack of activity, even though ‘Oumuamua passed within 0.25 au of the Sun

Atlantic salmon male post-smolt maturation can be reduced by using a 3-hour scotophase when inducing smoltification

Photoperiod regulates the occurrence of unwanted male post-smolt maturation during the production of large (>100 g) Atlantic salmon (Salmo salar) smolts. However, the optimal daylength for triggering smoltification, but not male puberty, has yet to be established. We used either continuous light (24:0 light/dark) or long days (18:6 and 21:3) after a six week “winter” zeitgeber (12:12) to induce smoltification in fish of around 120 g reared at 16 °C. The fish were sampled 1, 2, 3, and 6 weeks after the initiation of the three different photoperiod treatments (n = 153 males in total with 9–18 males/photoperiod/time point). As expected, the smoltification indicator gill Na+/K+-ATPase (NKA) was significantly (p < 0.05) elevated and peaked 2 to 3 weeks after the initiation of the different photoperiods. Pubertal males were identified in all treatments via the combined use of relative testis size and histology, plasma 11-ketotestosterone, changes in body condition, and growth rate. The total incidence of puberty was significantly higher among males on continuous light at 33% (n = 16/49) compared to 10% (6/61) and 12% (5/43) in 21:3 and 18:6, respectively. The incidence of puberty increased over time in all photoperiods, with 62% (8/13), 19% (3/16), and 38% (3/8) of the males from 24:0, 21:3, and 18:6 pubertal at week 6, respectively. The mean weight of males that went on to initiate puberty was significantly higher (13%) at the beginning of the trial compared to those that remained immature (mean weight, 127 vs 112 g, respectively), but there was no initial difference in body condition. Puberty significantly reduced gill NKA by 35% compared to immature males at week six but had no effect at earlier time-points. Photoperiod had no effect on the female GSI, and they were all considered immature. In conclusion, the incidence of male puberty during smoltification is regulated by photoperiod and leads to an earlier decline in a key indicator of seawater readiness. As such, photoperiods with a short scotophase (21:3 or 18:6) following the winter zeitgeber in a square-wave (long-short-long day) smolt regime are recommended to limit the incidence of male puberty.publishedVersio

Slow-light and evanescent modes at interfaces in photonic crystal waveguides: optimal extraction from experimental near-field measurements

We develop a systematic approach for simultaneous extraction of the dispersion relations and profiles of multiple modes in periodic waveguides though a special global optimization procedure applied to near-field electric field measurements in the waveguide plane. We apply this method to perform in-depth analysis of experimental data on wave propagation close to an interface between waveguide sections with different dispersion characteristics, and we successfully identify several modes contributing to the experimentally measured fields. We find clear evidence that when the group velocity is reduced across the interface, evanescent modes that facilitate the excitation of propagating slow-light waves appear, confirming previous theoretical predictions. (C) 2011 Optical Society of AmericaPublisher PDFPeer reviewe

Migration Fears, Policy Uncertainty and Economic Activity

Motivated by the recent European migrant crisis, Brexit, and President Trump's immigration priorities, we provide new evidence into how migration fears and migration policy uncertainty affect macroeconomic outcomes across France, Germany, the United Kingdom, and the United States. We investigate the impact of immigration-related fear and uncertainty on economic activity via vector autoregression models. Our findings indicate that both indices are associated with decreases in industrial production in all countries except Germany. Surprise increases in immigration-related fears have negative influence on unemployment rates in these four countries too. We also show that innovations in the migration related uncertainty indices do not foreshadow significant declines in output