New specimens of the basal ornithischian dinosaur Lesothosaurus diagnosticus Galton, 1978 from the Early Jurassic of South Africa

We describe new specimens of the basal ornithischian dinosaur Lesothosaurus diagnosticus Galton, 1978 collected from a bonebed in the Fouriesburg district of the Free State, South Africa. The material was collected from the upper Elliot Formation (Early Jurassic) and represents the remains of at least three individuals. These individuals are larger in body size than those already known in museum collections and offer additional information on cranial ontogeny in the taxon. Moreover, they are similar in size to the sympatric taxon Stormbergia dangershoeki. The discovery of three individuals at this locality might imply group-living behaviour in this early ornithischian.Palaeontologia africana 2016. ©2016 Paul M. Barrett, Richard J. Butler, Adam M. Yates, Matthew G. Baron&Jonah N. Choiniere. This is an open-access article published under the Creative Commons Attribution 4.0 Unported License (CC BY4.0). To view a copy of the license, please visit http://creativecommons.org/licenses/by/4.0/. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This item is permanently archived at: http://wiredspace.wits.ac.za/handle/10539/19886. The attached file is the published version of the article

Influence of solar wind on the Jovian thermosphere.

We aim to explain the reason why Jupiter's upper atmosphere is hotter than initial theories predicted by employing a coupled magnetosphere, ionosphere and thermosphere model. We use this coupled model to study how changes in upstream solar wind dynamic pressure affect Jupiter's thermospheric dynamics, energy balance, aurora and magnetosphere-ionosphere coupling currents. The variation in solar wind pressure is investigated on long (_50 Jovian days) and short (3 hours) time scales, which we respectively refer to as steady state and transient state. We vary the solar wind pressure by changing the size of the magnetosphere, as these two parameters are inversely correlated. In steady state, three different configurations are used: compressed, average and expanded magnetospheres. We find that the power dissipated by Joule heating and ion drag increases by —190% from a compressed to expanded magnetosphere. For transient modelling, the magnetosphere is compressed and expanded in a period of 3 hours. Compressions cause a reversal in momentum transfer between the thermosphere and magnetosphere. Compressions and expansions lead to at least a factor-of-two increase in ion drag and Joule heating, resulting in a —2000 TW increase in total power dissipated in the thermosphere and local temperature variations 25 K. Compressions also cause a —450% increase in auroral UV emission whilst expansions increase UV emission modestly by —37%. While these analyses do not provide a definitive answer to the elevated Jovian thermospheric temperature, they show that, in moving from a steady-state to a time-dependent paradigm, the thermospheric response to magnetospheric reconfiguration is characterised by dramatically different distributions of temperature and wind. In particular, magnetospheric compressions produce extensive cells of equatorward flow emanating from the auroral zone, suggesting that a Jovian-like magnetosphere subject to adequately frequent, repeated episodes of contraction/expansion may possess elevated thermospheric temperatures, perhaps even at the level of those observed

Magnetosphere‐Ionosphere‐Thermosphere coupling at Jupiter using a three‐dimensional atmospheric general circulation model

Jupiter's upper atmosphere is ∼700 K hotter than predicted based on solar extreme ultraviolet heating alone. The reason for this still remains a mystery and is known as the “energy crisis.” It is thought that the interaction between Jupiter and its dynamic magnetosphere plays a vital role in heating its atmosphere to the observed temperatures. Here, we present a new model of Jupiter's magnetosphere‐ionosphere‐thermosphere‐coupled system where we couple a three‐dimensional atmospheric general circulation model to an axisymmetric magnetosphere model. We find that the model temperatures are on average ∼60 K, with a maximum of ∼200 K, hotter than the model's two‐dimensional predecessor making our high‐latitude temperatures comparable to the lower limit of observations. Stronger meridional winds now transport more heat from the auroral region to the equator increasing the equatorial temperatures. However, despite this increase, the modeled equatorial temperatures are still hundreds of kelvins colder than observed. We use this model as an intermediate step toward a three‐dimensional atmospheric model coupled to a realistic magnetosphere model with zonal and radial variation

Whistler mode waves upstream of Saturn

Whistler mode waves are generated within and can propagate upstream of collisionless shocks. They are known to play a role in electron thermodynamics/acceleration and, under certain conditions, are markedly observed as wave trains preceding the shock ramp. In this paper, we take advantage of Cassini's presence at ~10 AU to explore the importance of whistler mode waves in a parameter regime typically characterized by higher Mach number (median of ~14) shocks, as well as a significantly different interplanetary magnetic field structure, compared to near Earth. We identify electromagnetic precursors preceding a small subset of bow shock crossings with properties which are consistent with whistler mode waves. We find these monochromatic, low-frequency, and circularly polarized waves to have a typical frequency range of 0.2–0.4 Hz in the spacecraft frame. This is due to the lower ion and electron cyclotron frequencies near Saturn, between which whistler waves can develop. The waves are also observed as predominantly right handed in the spacecraft frame, the opposite sense to what is typically observed near Earth. This is attributed to the weaker Doppler shift, owing to the large angle between the solar wind velocity and magnetic field vectors at 10 AU. Our results on the low occurrence of whistler waves upstream of Saturn also underpin the predominantly supercritical bow shock of Saturn

Exploring Graphs with Time Constraints by Unreliable Collections of Mobile Robots

A graph environment must be explored by a collection of mobile robots. Some of the robots, a priori unknown, may turn out to be unreliable. The graph is weighted and each node is assigned a deadline. The exploration is successful if each node of the graph is visited before its deadline by a reliable robot. The edge weight corresponds to the time needed by a robot to traverse the edge. Given the number of robots which may crash, is it possible to design an algorithm, which will always guarantee the exploration, independently of the choice of the subset of unreliable robots by the adversary? We find the optimal time, during which the graph may be explored. Our approach permits to find the maximal number of robots, which may turn out to be unreliable, and the graph is still guaranteed to be explored. We concentrate on line graphs and rings, for which we give positive results. We start with the case of the collections involving only reliable robots. We give algorithms finding optimal times needed for exploration when the robots are assigned to fixed initial positions as well as when such starting positions may be determined by the algorithm. We extend our consideration to the case when some number of robots may be unreliable. Our most surprising result is that solving the line exploration problem with robots at given positions, which may involve crash-faulty ones, is NP-hard. The same problem has polynomial solutions for a ring and for the case when the initial robots' positions on the line are arbitrary. The exploration problem is shown to be NP-hard for star graphs, even when the team consists of only two reliable robots

Spina bifida-predisposing heterozygous mutations in Planar Cell Polarity genes and Zic2 reduce bone mass in young mice

Fractures are a common comorbidity in children with the neural tube defect (NTD) spina bifida. Mutations in the Wnt/planar cell polarity (PCP) pathway contribute to NTDs in humans and mice, but whether this pathway independently determines bone mass is poorly understood. Here, we first confirmed that core Wnt/PCP components are expressed in osteoblasts and osteoclasts in vitro. In vivo, we performed detailed µCT comparisons of bone structure in tibiae from young male mice heterozygous for NTD-associated mutations versus WT littermates. PCP signalling disruption caused by Vangl2 (Vangl2Lp/+) or Celsr1 (Celsr1Crsh/+) mutations significantly reduced trabecular bone mass and distal tibial cortical thickness. NTD-associated mutations in non-PCP transcription factors were also investigated. Pax3 mutation (Pax3Sp2H/+) had minimal effects on bone mass. Zic2 mutation (Zic2Ku/+) significantly altered the position of the tibia/fibula junction and diminished cortical bone in the proximal tibia. Beyond these genes, we bioinformatically documented the known extent of shared genetic networks between NTDs and bone properties. 46 genes involved in neural tube closure are annotated with bone-related ontologies. These findings document shared genetic networks between spina bifida risk and bone structure, including PCP components and Zic2. Genetic variants which predispose to spina bifida may therefore independently diminish bone mass

Osteological and Soft-Tissue Evidence for Pneumatization in the Cervical Column of the Ostrich (Struthio camelus) and Observations on the Vertebral Columns of Non-Volant, Semi-Volant and Semi-Aquatic Birds

© 2015 Apostolaki et al. This is an open access article distributed under the terms of the Creative Commons Attribution License [4.0], which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published version of the article

Rationale and study design for a randomised controlled trial to reduce sedentary time in adults at risk of type 2 diabetes mellitus: project stand (Sedentary Time ANd diabetes)

<p>Abstract</p> <p>Background</p> <p>The rising prevalence of Type 2 Diabetes Mellitus (T2DM) is a major public health problem. There is an urgent need for effective lifestyle interventions to prevent the development of T2DM. Sedentary behaviour (sitting time) has recently been identified as a risk factor for diabetes, often independent of the time spent in moderate-to-vigorous physical activity. Project STAND (<it>Sedentary Time ANd Diabetes</it>) is a study which aims to reduce sedentary behaviour in younger adults at high risk of T2DM.</p> <p>Methods/Design</p> <p>A reduction in sedentary time is targeted using theory driven group structured education. The STAND programme is subject to piloting and process evaluation in line with the MRC framework for complex interventions. Participants are encouraged to self-monitor and self-regulate their behaviour. The intervention is being assessed in a randomised controlled trial with 12 month follow up. Inclusion criteria are a) aged 18-40 years with a BMI in the obese range; b) 18-40 years with a BMI in the overweight range plus an additional risk factor for T2DM. Participants are randomised to the intervention (n = 89) or control (n = 89) arm. The primary outcome is a reduction in sedentary behaviour at 12 months as measured by an accelerometer (count < 100/min). Secondary outcomes include physical activity, sitting/lying time using the ActivPAL posture monitor, fasting and 2 h oral glucose tolerance test, lipids, inflammatory biomarkers, body weight, waist circumference, blood pressure, illness perceptions, and efficacy beliefs for behaviour change.</p> <p>Conclusions</p> <p>This is the first UK trial to address sedentary behaviour change in a population of younger adults at risk of T2DM. The results will provide a platform for the development of a range of future multidisciplinary interventions in this rapidly expanding high-risk population.</p> <p>Trial registration</p> <p>Current controlled trials <a href="http://www.controlled-trials.com/ISRCTN08434554">ISRCTN08434554</a>, MRC project 91409.</p

Chromosomal-level assembly of the Asian Seabass genome using long sequence reads and multi-layered scaffolding

We report here the ~670 Mb genome assembly of the Asian seabass (Lates calcarifer), a tropical marine teleost. We used long-read sequencing augmented by transcriptomics, optical and genetic mapping along with shared synteny from closely related fish species to derive a chromosome-level assembly with a contig N50 size over 1 Mb and scaffold N50 size over 25 Mb that span ~90% of the genome. The population structure of L. calcarifer species complex was analyzed by re-sequencing 61 individuals representing various regions across the species' native range. SNP analyses identified high levels of genetic diversity and confirmed earlier indications of a population stratification comprising three clades with signs of admixture apparent in the South-East Asian population. The quality of the Asian seabass genome assembly far exceeds that of any other fish species, and will serve as a new standard for fish genomics