3,786 research outputs found
Flow-Based Network Analysis of the Caenorhabditis elegans Connectome
We exploit flow propagation on the directed neuronal network of the nematode C. elegans to reveal dynamically relevant features of its connectome. We find flow-based groupings of neurons at different levels of granularity, which we relate to functional and anatomical constituents of its nervous system. A systematic in silico evaluation of the full set of single and double neuron ablations is used to identify deletions that induce the most severe disruptions of the multi-resolution flow structure. Such ablations are linked to functionally relevant neurons, and suggest potential candidates for further in vivo investigation. In addition, we use the directional patterns of incoming and outgoing network flows at all scales to identify flow profiles for the neurons in the connectome, without pre-imposing a priori categories. The four flow roles identified are linked to signal propagation motivated by biological input-response scenarios
Cellular mechanisms in sympathoâmodulation of the heart
Cardiovascular function relies on complex servo-controlled regulation mechanisms that involve both fast-acting feedback responses and long-lasting adaptations affecting the gene expression. The adrenergic system, with its specific receptor subtypes and intracellular signalling cascades provides the major regulatory system, while the parasympathetic system plays a minor role. At the molecular level, Ca2+ acts as the general signal trigger for the majority of cell activities including contraction, metabolism and growth. During recent years, important new results have emerged allowing an integrated view of how the multifarious Ca2+-signalling mechanisms transmit adrenergic impulses to intracellular target sites. These insights into cellular and molecular mechanisms are pivotal in improving pharmacological control of the sympathetic responses to surgical trauma and perioperative stress. They are examined in detail in this review, with particular emphasis being given to the differences in intracellular signalling between cardiomyocytes and vascular smooth muscle cell
Approximate roots of a valuation and the Pierce-Birkhoff Conjecture
This paper is a step in our program for proving the Piece-Birkhoff Conjecture
for regular rings of any dimension (this would contain, in particular, the
classical Pierce-Birkhoff conjecture which deals with polynomial rings over a
real closed field). We first recall the Connectedness and the Definable
Connectedness conjectures, both of which imply the Pierce - Birkhoff
conjecture. Then we introduce the notion of a system of approximate roots of a
valuation v on a ring A (that is, a collection Q of elements of A such that
every v-ideal is generated by products of elements of Q). We use approximate
roots to give explicit formulae for sets in the real spectrum of A which we
strongly believe to satisfy the conclusion of the Definable Connectedness
conjecture. We prove this claim in the special case of dimension 2. This proves
the Pierce-Birkhoff conjecture for arbitrary regular 2-dimensional rings
Surface structure of i-Al(68)Pd(23)Mn(9): An analysis based on the T*(2F) tiling decorated by Bergman polytopes
A Fibonacci-like terrace structure along a 5fold axis of i-Al(68)Pd(23)Mn(9)
monograins has been observed by T.M. Schaub et al. with scanning tunnelling
microscopy (STM). In the planes of the terraces they see patterns of dark
pentagonal holes. These holes are well oriented both within and among terraces.
In one of 11 planes Schaub et al. obtain the autocorrelation function of the
hole pattern. We interpret these experimental findings in terms of the
Katz-Gratias-de Boisseu-Elser model. Following the suggestion of Elser that the
Bergman clusters are the dominant motive of this model, we decorate the tiling
T*(2F) by the Bergman polytopes only. The tiling T*(2F) allows us to use the
powerful tools of the projection techniques. The Bergman polytopes can be
easily replaced by the Mackay polytopes as the decoration objects. We derive a
picture of ``geared'' layers of Bergman polytopes from the projection
techniques as well as from a huge patch. Under the assumption that no surface
reconstruction takes place, this picture explains the Fibonacci-sequence of the
step heights as well as the related structure in the terraces qualitatively and
to certain extent even quantitatively. Furthermore, this layer-picture requires
that the polytopes are cut in order to allow for the observed step heights. We
conclude that Bergman or Mackay clusters have to be considered as geometric
building blocks of the i-AlPdMn structure rather than as energetically stable
entities
Formal Reasoning Using an Iterative Approach with an Integrated Web IDE
This paper summarizes our experience in communicating the elements of
reasoning about correctness, and the central role of formal specifications in
reasoning about modular, component-based software using a language and an
integrated Web IDE designed for the purpose. Our experience in using such an
IDE, supported by a 'push-button' verifying compiler in a classroom setting,
reveals the highly iterative process learners use to arrive at suitably
specified, automatically provable code. We explain how the IDE facilitates
reasoning at each step of this process by providing human readable verification
conditions (VCs) and feedback from an integrated prover that clearly indicates
unprovable VCs to help identify obstacles to completing proofs. The paper
discusses the IDE's usage in verified software development using several
examples drawn from actual classroom lectures and student assignments to
illustrate principles of design-by-contract and the iterative process of
creating and subsequently refining assertions, such as loop invariants in
object-based code.Comment: In Proceedings F-IDE 2015, arXiv:1508.0338
Die gute alte Fruchtfolge als BekÀmpfungsmethode gegen den Maiswurzelbohrer (Diabrotica virgifera virgifera LeConte)
Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae), the western corn rootworm
(WCR), is an immigrant from North America and one of the top ten global agricultural
pest species. Within the last 15 years, WCR invaded Europe at 3 focal points, and has
been steadily extending its domain soon threatening commercial maize production.
After the first detection in Switzerland in 2000 near Lugano, careful observations by
pheromone trap monitoring of this quarantine organism have been realized.
Experiences with WCR whose populations dynamics are incompletely understood,
have also been studied by installing a continuous maize field comparing population
dynamics with rotated maize fields in the immediate surroundings. Our experiences
with WCR populations in the Swiss territory are here briefly summarized:
1. Mandatory crop rotation in the canton Ticino slowed spread of WCR significantly.
WCR infestations north of the main Alpine mountain chain were rare and eradicated
by crop rotation. 2. In a continuous maize cropping system population of WCR can
reach economic damage level, but can also be confined by unknown factors 3.
Switzerland with its rigorous crop rotation program may serve as an example of farsighted
WCR management preserving environment and saving money
Taking an ethics of care perspective on two university teacher training programmes
This paper shows the usefulness and interest of taking an ethics of care perspective to evaluate university teacher training programmes. More precisely, in this case study we use the five elements of care identified by Tronto â attentiveness, responsibility, competence, responsiveness and trust â to assess two multiple-day training programmes offered at the University of Geneva. We show how small changes in our practice such as giving some choice to the participants over the topics addressed, adapting the schedule to meet the participantsâ constraints or dedicating time slots specifically for the questions and concerns raised by the participants can have a big impact on the level of care provided. We moreover argue that this framework brings interesting and novel elements that appropriately âcounterbalancesâ traditional evaluations that are usually implicitly based on notions such as performance, efficiency and measurability. Finally, we briefly explain how the ethics of care could be used a basis to not only evaluate but to rethink and elaborate training programmes
Perioperative Strategien zur Regulierung des Sympathikotonus
Zusammenfassung: Obwohl fĂŒr verschiedene therapeutische Konzepte zur Verminderung der kardialen perioperativen MorbiditĂ€t und MortalitĂ€t zunehmend Evidenz vorliegt, bleibt die tatsĂ€chliche Umsetzung solcher Konzepte im klinischen Alltag oft aus. Zwar ist einem groĂen Teil der klinisch tĂ€tigen Ărzte die wachsende Literatur bekannt; dieses Wissen wird aber nur in einem Teil der FĂ€lle angewendet, selbst wenn allgemein akzeptierte Indikationen bestehen. Die vorliegende Ăbersichtsarbeit hat deshalb zum Ziel, die GrĂŒnde fĂŒr die mangelnde Umsetzung aufzuzeigen und nochmals die wesentlichen Grundlagen sowie die klinische Bedeutung einzelner Strategien einschlieĂlich des α2-Agonismus, der ÎČ-adrenergen Blockade und der RegionalanĂ€sthesien zusammenzufassen. Dies insbesondere im Hinblick auf die klinische Anwendung dieser Konzepte in einem allgemeinanĂ€sthesiologischen Umfeld. Zudem wird ein Ausblick in die auf "gene profiling" basierende individualisierte Pharmakotherapie der perioperativen Medizin von morgen gegebe
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