Were Dinosaurs Cold- or Warm-Blooded?: An Exercise in Scientific Inference

This exercise introduces students to scientific inference. They will infer the mode of thermal regulation of dinosaurs (i.e., were they cold- or warm-blooded?) by comparing the relative brain size of dinosaurs to that of modern vertebrates. In the past 20 years, several lines of evidence have been introduced that suggest that dinosaurs were warm-blooded, not cold-blooded as traditionally thought. The size of the brain relative to the size of the body is one line of evidence. Modern mammals and birds are warm-blooded and have large brains relative to the size of their bodies, whereas reptiles are cold-blooded and have small brains relative to their body size (Martin, 1981). Thus, if we can estimate the relative brain size of dinosaurs we can make inferences as to their mode of thermal regulation; however, since dinosaurs are only known from fossilized specimens (except in Jurassic Park!), we must estimate this value

Relative size of brain and cerebrum in Tyrannosaurus rex: an analysis using brain-endocast quantitative relationships in extant alligators

Brain and cerebrum mass are estimated from endocasts of three tyrannosaurid taxa (Tyrannosaurus rex, Gorgosaurus, and Nanotyrannus) using morphological and quantitative brain-endocast relations in a size series of sexually mature alligators (Alligator mississippiensis). The alligator size series (N = 12) ranged from the smallest sexually mature size to the largest size commonly encountered. Alligator brain mass (MBr) increased regularly with increasing body mass, while the ratio of brain mass to endocast volume (MBr:EV) declined regularly from 67 percent to 32 percent. The ratio of cerebrum mass to cerebrocast was 38 percent in the largest alligators and regularly exceeded the MBr:EV ratio by 5.6 percent. For estimates from endocasts of non-avian dinosaurs of unknown sex, a MBr:EV ratio of 37 percent was used, the mean of the ratio of the largest male and female alligators. A corresponding 42 percent ratio was used for the cerebrum-cerebrocast ratio. Relative brain size was measured as Encephalization Quotients (EQs) based on brain-body relations in extant non-avian reptiles (REQs) and birds (BEQs). Tyrannosaurus rex has the relatively largest brain of all adult non-avian dinosaurs, excepting certain small maniraptoriforms (Troodon, Bambiraptor, and Ornithomimus), which are well within the extant bird relative brain size range. The relative brain size of T. rex is within the range of extant non-avian reptiles and, at most, 2 standard deviations (SDs) above the mean of non-avian reptile log REQs, which are normally distributed. Gorgosaurus REQs overlapped the lower end of the T. rex. Log BEQs of all theropods, excepting small maniraptoriforms, were well below the range of extant birds. Nanotyrannus log REQs were anomalously high for an adult, but the difference between Nanotyrannus log REQs and T. rex values paralleled the difference between log REQs of the smallest subadult and largest alligators. Nanotyrannus cerebrum:brain ratios were also consistent with those of an older juvenile or youngest subadult. Cerebrocast:endocast ratios of the three T. rex endocasts ranged from 41.1 to 43.5 percent, and cerebrum mass:brain mass (MCb:MBr) ratios range from 47.5 to 49.53 percent, more than the lowest ratios for extant birds (44.6 percent) but very close to ratios (45.9–47.9 percent) typical of the smallest sexually mature alligators. In Carcharodontosaurus saharicus, these ratios were 37.1 percent and 42.1 percent, respectively, the latter essentially identical to actual MCb:MBr ratios (40.76–42.91 percent) of the two largest alligators. Although the relative brain size of Carcharodontosaurus (SGM-Din 1), was approximately two thirds that of T. rex, the MCb:MBr ratio of the former was only 5.5–7.5 percent less than that of T. rex

Body mass estimates of phytosaurs (Archosauria: Parasuchidae) from the Petrified Forest Formation (Chinle Group: Revueltian : early-mid Norian) based on skull and limb bone measurements

Phytosaurs were the largest and most common semi-aquatic predators of the Late Triassic. Although their skulls are relatively common in the fossil record, articulated, or even associated skeletons are extremely rare, so it has always been difficult to gauge just how large (mass or length) an individual phytosaur may have been. Body mass in particular is an important physiological variable, often used for the scaling of organs, biomass determination, biomechanics, and locomotion. We take advantage of phytosaurs’ general similarity to extant crocodilians to attempt to reconstruct body mass and length based on measurements of the skulls and limbs of phytosaurs from the Upper Triassic Snyder and Canjilon quarries in north-central New Mexico. These quarries, in the Painted Desert Member of the Petrified Forest Formation (Revueltian: early-mid Norian) preserve catastrophic death assemblages that appear to well-represent discrete populations of phytosaurs. We also utilize a snout-vent measurement based on an articulated skeleton from the Canjilon quarry to compare the accuracy of different equations based on discrete limb elements. Body mass estimates for Snyder quarry phytosaurs range between 25 and 500 kg, with most specimens yielding estimates of approximately 200-350 kg. The Canjilon quarry sample encompasses fewer juveniles and more robust adults, including one individual that may have weighed as much as 535 kg. From equations based on nine extant crocodilian genera, these Revueltian phytosaurs appear to have approached 4.5 m total body length for a ~ 400 kg phytosaur. The prevalence of subadult to adult phytosaurs in both quarries based on body mass estimates corroborates qualitative estimates of the population structure based on skull sizes alone, thereby reinforcing the hypothesis that both quarries are catastrophic assemblages

The Graph Database: Jack of All Trades or Just Not SQL?

This special issue of IT Professional focuses on the graph database. The graph database, a relatively new phenomenon, is well suited to the burgeoning information era in which we are increasingly becoming immersed. Here, the guest editors briefly explain how a graph database works, its relation to the relational database management system (RDBMS), and its quantitative and qualitative pros and cons, including how graph databases can be harnessed in a hybrid environment. They also survey the excellent articles submitted for this special issue

The Interaction Of Multiple Convection Zones In A-type Stars

A-type stars have a complex internal structure with the possibility of multiple convection zones. If not sufficiently separated, such zones will interact through the convectively stable regions that lie between them. It is therefore of interest to ask whether the typical conditions that exist within such stars are such that these convections zones can ever be considered as disjoint. In this paper we present results from numerical simulations that help in understanding how increasing the distance between the convectively unstable regions are likely to interact through the stable region that separates them. This has profound implications for mixing and transport within these stars.Comment: 9 pages, 15 figures, Preprint accepted for publication in MNRA

Heliophysics Event Knowledgebase for the Solar Dynamics Observatory and Beyond

The immense volume of data generated by the suite of instruments on SDO requires new tools for efficient identifying and accessing data that is most relevant to research investigations. We have developed the Heliophysics Events Knowledgebase (HEK) to fill this need. The HEK system combines automated data mining using feature-detection methods and high-performance visualization systems for data markup. In addition, web services and clients are provided for searching the resulting metadata, reviewing results, and efficiently accessing the data. We review these components and present examples of their use with SDO data.Comment: 17 pages, 4 figure

Spectrum and amplitudes of internal gravity waves excited by penetrative convection in solar-type stars

The excitation of internal gravity waves by penetrative convective plumes is investigated using 2-D direct simulations of compressible convection. The wave generation is quantitatively studied from the linear response of the radiative zone to the plumes penetration, using projections onto the g-modes solutions of the associated linear eigenvalue problem for the perturbations. This allows an accurate determination of both the spectrum and amplitudes of the stochastically excited modes. Using time-frequency diagrams of the mode amplitudes, we then show that the lifetime of a mode is around twice its period and that during times of significant excitation up to 40% of the total kinetic energy may be contained into g-modes.Comment: 13 pages, 19 figures, accepted for publication in A&

On the Currents and Transports Connected With the Atlantic Meridional Overturning Circulation in the Subpolar North Atlantic

Results from an interannually forced, 0.08 degrees eddy-resolving simulation based on the Hybrid Coordinate Ocean Model, in conjunction with a small but well-determined transport database, are used to investigate the currents and transports associated with the Atlantic meridional overturning circulation (AMOC) in the subpolar North Atlantic (SPNA). The model results yield a consistent warming in the western SPNA since the early 1990s, along with mean transports similar to those observed for the trans-basin AMOC across the World Ocean Circulation Experiment hydrographic section AR19 (16.4 Sv) and boundary currents at the exit of the Labrador Sea near 53 degrees N (39.0 Sv) and east of the Grand Banks near 43 degrees N (15.9 Sv). Over a 34 year integration, the model-determined AMOC across the AR19 section and the western boundary current near 53 degrees N both exhibit no systematic trend but some long-term (interannual and longer) variabilities, including a decadal transport variation of 3-4 Sv from relatively high in the 1990s to low in the 2000s. The decadal variability of the model boundary current transport near 53 degrees N lags the observed winter time North Atlantic Oscillation index by about 2 years and leads the model AMOC across the AR19 section by about 1 year. The model results also show that the long-term variabilities are low compared to those on shorter time scales. Thus, rapid sampling of the current over long time intervals is required to filter out high-frequency variabilities in order to determine the lower frequency variabilities of interest. Citation: Xu, X., H. E. Hurlburt, W. J. Schmitz Jr., R. Zantopp, J. Fischer, and P. J. Hogan (2013), On the currents and transports connected with the atlantic meridional overturning circulation in the subpolar North Atlantic, J. Geophys. Res. Oceans, 118, 502-516, doi:10.1002/jgrc.20065

Structural Biology of Peanut Allergens

Peanuts are a cause of one of the most common food allergies. Allergy to peanuts not only affects a significant fraction of the population, but it is relatively often associated with strong reactions in sensitized individuals. Peanut and tree nut allergies, which start in childhood are often persistent and continue through life, as opposed to other food allergies that resolve with age. Cherefore, peanut allergens are one of the most intensively studied food allergens. In this review we focus on the structural studies of peanut allergens. Despite the fact that these allergens are attracting a lot of interest and several of them have had their structures experimentally determined, still some molecular properties of peanut allergens are not well understood. Peanut allergens like other allergens belong to just a few protein families. Allergens from the cupin superfamily (Ara h 1 and Ara h 3), 2S albumins (Arah 2 and Ara h 6), Ara h 8 (pathogenesis related class-10 protein) and Ara h 5 (profilin) are relatively well characterized in terms of their 3D structures. However some peanut allergens like Ara h 7 (2S albumin), Ara h 9 (nonspecific lipid-transfer protein), and especially oleosins (Ara h 10 and Ara h 11) and defensins (Ara h 12 and Ara h 13), still are waiting for such characterization