A hydrodynamic theory of premixed flame propagation within closed vessels is developed assuming the flame is much thinner than all other fluid dynamic lengths. In this limit, the flame is confined to a surface separating the unburned mixture from burned combustion products, and propagates at a speed determined from the analysis of its internal structure. Unlike freely propagating flames that propagate under nearly isobaric conditions, combustion in a closed vessel results in continuous increases in pressure, burning rate and flame temperature, and a progressive decrease in flame thickness. The flame speed is shown to depend on the voluminal stretch rate, which measures the deformation of a volume element of the flame zone, and on the rate of pressure rise. Both effects are modulated by pressure-dependent Markstein numbers that depend on heat release and mixture properties while capturing the effects of temperature-dependent transport and stoichiometry. The model applies to flames of arbitrary shape propagating in general flows, laminar or turbulent, within vessels of general configurations. The main limitation of hydrodynamic flame theories is the assumption that variations inside the flame zone due to chemistry or turbulence, which could potentially alter its internal structure, are physically unresolved. Nonetheless, the theory, deduced from physical first principles, identifies the various mechanisms involved in the combustion process as demonstrated in detailed discussions of planar flames propagating in rectangular channels and spherically expanding flames in spherical vessels. It also enables the construction of instructive models to numerically simulate the evolution of multi-dimensional and corrugated flames under confinement.

Carrot is an important vegetable crop worldwide valued for its fleshy edible roots of varied colours. Owing to its highly cross-pollinated nature and small flower size, cytoplasmic male sterility (CMS) is being utilized for hybrid development. Among different types of male sterility, petaloid CMS is widely used for hybrid carrot breeding globally. This study aimed to develop selection criteria for parents in developing heterotic F1 hybrids using CMS lines. A large number of agro-morphological traits and Simple Sequence Repeats (genomic-SSRs) were used to assess the diversity among parental lines. We developed 60 F1 hybrids by crossing four petaloid CMS lines and 15 testers in line × tester mating design and evaluated them in replicated randomized block design trial for four vegetative and 11 economic traits. The mean squares of all the traits in line × tester interactions were significant. The estimates of genetic components of variance indicated predominance of non-additive gene action except for root maturity, root length and core diameter. The hybrids with highest per se performance also had significant positive specific combining ability effects. The root yield and root weight showed highest heterosis percentage (33%). The best performing heterotic hybrids were DCatH-5392, DCatH-700 and DCatH-9892. Correlation between genetic distance and relative heterosis of economic traits indicated no significant association and thus genetic distance could not be used to predict heterosis. As most of the yield-related traits were controlled by non-additive gene action, heterosis breeding could be potentially used along with combining ability analysis to reduce time in selection of best parents and crosses in tropical carrot.

We describe system verification tests and early science results from the pulsar processor (PTUSE) developed for the newly commissioned 64-dish SARAO MeerKAT radio telescope in South Africa. MeerKAT is a high-gain ( ${\sim}2.8\,\mbox{K Jy}^{-1}$ ) low-system temperature ( ${\sim}18\,\mbox{K at }20\,\mbox{cm}$ ) radio array that currently operates at 580–1 670 MHz and can produce tied-array beams suitable for pulsar observations. This paper presents results from the MeerTime Large Survey Project and commissioning tests with PTUSE. Highlights include observations of the double pulsar $\mbox{J}0737{-}3039\mbox{A}$ , pulse profiles from 34 millisecond pulsars (MSPs) from a single 2.5-h observation of the Globular cluster Terzan 5, the rotation measure of Ter5O, a 420-sigma giant pulse from the Large Magellanic Cloud pulsar PSR $\mbox{J}0540{-}6919$ , and nulling identified in the slow pulsar PSR J0633–2015. One of the key design specifications for MeerKAT was absolute timing errors of less than 5 ns using their novel precise time system. Our timing of two bright MSPs confirm that MeerKAT delivers exceptional timing. PSR $\mbox{J}2241{-}5236$ exhibits a jitter limit of $<4\,\mbox{ns h}^{-1}$ whilst timing of PSR $\mbox{J}1909{-}3744$ over almost 11 months yields an rms residual of 66 ns with only 4 min integrations. Our results confirm that the MeerKAT is an exceptional pulsar telescope. The array can be split into four separate sub-arrays to time over 1 000 pulsars per day and the future deployment of S-band (1 750–3 500 MHz) receivers will further enhance its capabilities.

We describe a simple method to objectively identify the threshold for edge detection in morphometric measurement of brain structures. This method correlates highly with the subjective operator-driven approach to edge detection. While the objective approach, using a histogram of pixel intensities, reduces rater bias and may reliably identify brain-CSF boundaries, its value in morphometric measurements of smaller cerebral structures may be somewhat limited.

Introduction: Online medical education resources are widely used in emergency medicine (EM), but strategies to assess quality remain elusive. We previously derived the Medical Education Translational Resources: Impact and Quality (METRIQ) 8 instrument to evaluate quality in medical education blog posts. Methods: As part of a subsequent validation study (The METRIQ Blog Study), a mixed-methods usability analysis was performed to obtain user feedback on the quality assessment instrument in order to improve its clarity and reliability. Participants in the METRIQ Study were first asked to rate five blog posts using the METRIQ-8 Score. They then evaluated the METRIQ-8 instruments ease of use and likelihood of being recommended to others using a 7-point Likert scale and free text comments. Participants were also asked to flag and comment on items within the score that they felt were unclear. Global usability ratings were summarized using median scores or percent rated unclear. We used ANOVA to test associations between ease of use and demographic factors. A thematic analysis was performed on the comments. Results: 309 EM medical students, residents, and attendings completed the survey. Global ratings were generally very favorable (median 2 [IQR 2-3], with 7 being the lowest score) for ease of use and likelihood of recommendation, and did not vary by participants country of origin, frequency of blog use, or learner level. Participants stated that the score was structured, systematic, and straightforward. They found it useful for junior learners and for guiding blog creation. Four questions in the score (questions 2, 4, 5, and 7) were identified by 10% of subjects to be unclear. Thematic analysis of comments identified suggested four main themes for improving the score: adding clearer definitions with marking rubrics; shortening the 7-point scale; adding items evaluating blog post presentation and utility; and, rephrasing the wording of certain questions for clarity. Conclusion: A mixed methods usability analysis of the METRIQ-8 instrument for assessing blog quality was globally well received by EM medical students, residents, and attendings. Qualitative analyses revealed multiple areas to improve the instruments clarity and usability. The METRIQ score is a promising instrument for evaluating the quality of blogs; further development and testing is needed to improve its utility.

The discovery of the first electromagnetic counterpart to a gravitational wave signal has generated follow-up observations by over 50 facilities world-wide, ushering in the new era of multi-messenger astronomy. In this paper, we present follow-up observations of the gravitational wave event GW170817 and its electromagnetic counterpart SSS17a/DLT17ck (IAU label AT2017gfo) by 14 Australian telescopes and partner observatories as part of Australian-based and Australian-led research programs. We report early- to late-time multi-wavelength observations, including optical imaging and spectroscopy, mid-infrared imaging, radio imaging, and searches for fast radio bursts. Our optical spectra reveal that the transient source emission cooled from approximately 6 400 K to 2 100 K over a 7-d period and produced no significant optical emission lines. The spectral profiles, cooling rate, and photometric light curves are consistent with the expected outburst and subsequent processes of a binary neutron star merger. Star formation in the host galaxy probably ceased at least a Gyr ago, although there is evidence for a galaxy merger. Binary pulsars with short (100 Myr) decay times are therefore unlikely progenitors, but pulsars like PSR B1534+12 with its 2.7 Gyr coalescence time could produce such a merger. The displacement (~2.2 kpc) of the binary star system from the centre of the main galaxy is not unusual for stars in the host galaxy or stars originating in the merging galaxy, and therefore any constraints on the kick velocity imparted to the progenitor are poor.

Acromelic dysplasias are a group of skeletal dysplasias characterised by short-limbed short stature with other distinctive phenotypic features including small hands and feet and stiff joints. Geleophysic dysplasia is an acromelic dysplasia that is associated with characteristic facial features, progressive cardiac valvular thickening, and tracheal stenosis. Owing to overlapping clinical features with other types of short-limbed skeletal dysplasias, it is important to make a precise diagnosis as they have different cardiac morbidity and mortality. We present the cases of three patients with geleophysic dysplasia and progressive mitral valve disease to emphasise the natural history of this disorder and provide guidance regarding cardiac health supervision in these individuals.

Introduction: The use of free open access medicine, particularly open educational resources (OERs), by medical educators and learners continues to increase. As OERs, especially blogs and podcasts, rise in popularity, their ease of dissemination raises concerns about their quality. While critical appraisal of primary research and journal articles is formally taught, no training exists for the assessment of OERs. Thus, the ability of educators and learners to effectively assess the quality of OERs using gestalt alone has been questioned. Our goal is to determine whether gestalt is sufficient for emergency medicine learners (EM) and physicians to consistently rate and reliably recommend OERs to their colleagues. We hypothesized that EM physicians and learners would differ substantively in their assessment of the same resources. Methods: Participants included 31 EM learners and 23 EM attending physicians from Canada and the U.S. A modified Dillman technique was used to administer 4 survey blocks of 10 blog posts per subject between April and August, 2015. Participants were asked whether they would recommend each OER to 1) a learner or 2) an attending physician. The ratings reliability was assessed using single measures intraclass correlations and their correlations amongst the groups were assessed using Spearman’s rho. Family-wise adjustments were made for multiple comparisons using the Bonferroni technique. Results: Learners demonstrated poor reliability when recommending resources for other learners (ICC= 0.21, 95% CI 0.13-0.39) and attending physicians (ICC = 0.16, 95% CI=0.09-0.30). Similarly, attendings had poor reliability when recommending resources for learners (ICC= 0.27, 95% CI 0.18-0.41) and other attendings (ICC=0.22, 95% CI 0.14-0.35). Learners and attendings demonstrated moderate consistency between them when recommending resources for learners (rs=0.494, p<.01) and attendings (rs=0.491, p<.01). Conclusion: Using a gestalt-based rating system is neither reliable nor consistent when recommending OERs to learners and attending physicians. Learners’ gestalt ratings for recommending resources for other learners and attendings were especially unreliable. Our findings suggests the need for structured rating systems to rate OERs.

Brazil today has a legal market that allows for foreign lawyers and foreign firms, but existing regulations are restrictive. Foreign lawyers cannot practice domestic law or litigation, nor can Brazilian‐licensed lawyers working for foreign firms or partnering with foreign lawyers. This was not always the case, however. Until 1963, there was little regulation of the legal profession. Beginning in 1913, elite US lawyers traveled to Brazil, with some even becoming prominent domestic practitioners. They partnered with local elite lawyers (who maintained their domestic privileges) and served as key brokers for US businesses seeking market entry. Drawing on the elite theory literature, and on ethnographies, interview data, and over 1,000 pages of rare Portuguese and English archival sources, this study's thesis is that sophisticated US and Brazilian legal elites capitalized on the lack of regulation to advance their financial interests, and in the process transformed Brazil's corporate legal sector.