1,712 research outputs found

    A new skeleton of the cryptoclidid plesiosaur Tatenectes laramiensis reveals a novel body shape among plesiosaurs

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    Current knowledge of plesiosaurs of clade Cryptoclidia is constrained by a lack of fossils from outside the Oxford Clay deposits of England. Recent fieldwork in the Sundance Formation of the Bighorn Basin, Wyoming, has resulted in the recovery of significant new fossils of cryptoclidid plesiosaurs, including the small-bodied form Tatenectes laramiensis. A new partial skeleton of this taxon is reported here; it is the most complete and best-preserved example of the taxon found to date, comprising a complete dorsal vertebral series, many ribs and gastralia, and a complete pelvic girdle. This skeleton illuminates several unique features of the taxon, including a novel pattern of midline pachyostosis in the gastralia. In addition, a range of both axial and appendicular morphological features reveals that Tatenectes had a body shape unique among known plesiosaurs, characterized by extreme dorsoventral compression, and modest anteroposterior reduction. The combination of the new skeleton with information from previous finds allows the first reconstruction of the taxon. Tatenectes had a dorsoventrally compressed, oblate spheroid body shape, with a high skeletal mass concentration in the ventral elements. We hypothesize that these features were adaptations for increased near-surface stability, perhaps allowing access to above normal wave base, inshore environments in the shallow Sundance Seaway

    Odor supported place cell model and goal navigation in rodents

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    Experiments with rodents demonstrate that visual cues play an important role in the control of hippocampal place cells and spatial navigation. Nevertheless, rats may also rely on auditory, olfactory and somatosensory stimuli for orientation. It is also known that rats can track odors or self-generated scent marks to find a food source. Here we model odor supported place cells by using a simple feed-forward network and analyze the impact of olfactory cues on place cell formation and spatial navigation. The obtained place cells are used to solve a goal navigation task by a novel mechanism based on self-marking by odor patches combined with a Q-learning algorithm. We also analyze the impact of place cell remapping on goal directed behavior when switching between two environments. We emphasize the importance of olfactory cues in place cell formation and show that the utility of environmental and self-generated olfactory cues, together with a mixed navigation strategy, improves goal directed navigation

    Differential influences of environment and self-motion on place and grid cell firing

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    Place and grid cells in the hippocampal formation provide foundational representations of environmental location, and potentially of locations within conceptual spaces. Some accounts predict that environmental sensory information and self-motion are encoded in complementary representations, while other models suggest that both features combine to produce a single coherent representation. Here, we use virtual reality to dissociate visual environmental from physical motion inputs, while recording place and grid cells in mice navigating virtual open arenas. Place cell firing patterns predominantly reflect visual inputs, while grid cell activity reflects a greater influence of physical motion. Thus, even when recorded simultaneously, place and grid cell firing patterns differentially reflect environmental information (or ‘states’) and physical self-motion (or ‘transitions’), and need not be mutually coherent

    Modules for Prolog Revisited

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    Module systems are an essential feature of programming languages as they facilitate the re-use of existing code and the development of general purpose libraries. Unfortunately, there has been no consensual module system for Prolog, hence no strong development of libraries, in sharp contrast to what exists in Java for instance. One difficulty comes from the call predicate which interferes with the protection of the code, an essential task of a module system. By distinguishing the called module code protection from the calling module code protection, we review the existing syntactic module systems for Prolog. We show that no module system ensures both forms of code protection, with the noticeable exceptions of Ciao-Prolog and XSB. We then present a formal module system for logic programs with calls and closures, define its operational semantics and formally prove the code protection property. Interestingly, we also provide an equivalent logical semantics of modular logic programs without calls nor closures, which shows how they can be translated into constraint logic programs over a simple module constraint system

    Introductory Life Science Mathematics and Quantitative Neuroscience Courses

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    We describe two sets of courses designed to enhance the mathematical, statistical, and computational training of life science undergraduates at Emory College. The first course is an introductory sequence in differential and integral calculus, modeling with differential equations, probability, and inferential statistics. The second is an upper-division course in computational neuroscience. We provide a description of each course, detailed syllabi, examples of content, and a brief discussion of the main issues encountered in developing and offering the courses

    High-resolution spectroscopy of the R Coronae Borealis and Other Hydrogen Deficient Stars

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    High-resolution spectroscopy is a very important tool for studying stellar physics, perhaps, particularly so for such enigmatic objects like the R Coronae Borealis and related Hydrogen deficient stars that produce carbon dust in addition to their peculiar abundances. Examples of how high-resolution spectroscopy is used in the study of these stars to address the two major puzzles are presented: (i) How are such rare H-deficient stars created? and (ii) How and where are the obscuring soot clouds produced around the R Coronae Borealis stars?Comment: 16 pages, 9 figures, Astrophysics and Space Science Proceedings, Springer-Verlag, Berlin, 201

    University teachers’ views of interprofessional learning and their role in achieving outcomes - a qualitative study

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    Over the past decade, there has been a rapid increase in higher education institutions offering opportunities for interprofessional learning (IPL) to their students. The literature presents a number of factors that contribute to effective IPL, including having trained facilitators that help optimise the learning process. Many of these IPL facilitators are university teachers and the literature provides us with some insight into their views of IPL. However, little is known about university teachers’ views about IPL and their role in supporting students in achieving outcomes linked to IPL during their own teaching; this paper explores these areas. University teachers, working with students in Norway and England who contribute to patients’ care pathway were purposively invited to join focus groups. Data collected from the teachers’ conversations during these focus groups were analysed to elicit the main themes. Findings show that university teachers have a wide range of views about IPL, its potential to enhance collaborative practice and care, and their role in helping students achieve outcomes linked to IPL. A key challenge appears to be whether IPL is “worth the struggle,” which emphasises the need for strong leadership in order to align pedagogical approaches in education and practice that strive to achieve agreed outcomes
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