Recording single-channel activity of inositol trisphosphate receptors in intact cells with a microscope, not a patch clamp.

Optical single-channel recording is a novel tool for the study of individual Ca2+-permeable channels within intact cells under minimally perturbed physiological conditions. As applied to the functioning and spatial organization of IP3Rs, this approach complements our existing knowledge, which derives largely from reduced systems - such as reconstitution into lipid bilayers and patch clamping of IP3Rs on the membrane of excised nuclei - where the spatial arrangement and interactions among IP3Rs via CICR are disrupted. The ability to image the activity of single IP3R channels with millisecond resolution together with localization of their positions with a precision of a few tens of nanometers both raises several intriguing questions and holds promise of answers. In particular, what mechanism underlies the anchoring of puffs and blips to static locations; why do these Ca2+ release events appear to involve only a very small fraction of the IP3Rs within a cell; and how can we reconcile the relative immotility of functional IP3Rs with numerous studies reporting free diffusion of IP3R protein in the ER membrane

Studies of Sensor Data Interpretation for Asset Management of the Built Environment

Sensing in the built environment has the potential to reduce asset management expenditure and contribute to extending useful service life. In the built environment, measurements are usually performed indirectly; effects are measured remote from their causes. Modelling approximations from many sources, such as boundary conditions, geometrical simplifications and numerical assumptions result in important systematic uncertainties that modify correlation values between measurement points. In addition, conservative behavior models that were employed - justifiably during the design stage, prior to construction - are generally inadequate when explaining measurements of real behavior. This paper summarizes the special context of sensor data interpretation for asset management in the built environment. Nearly twenty years of research results from several doctoral thesis and fourteen full-scale case studies in four countries are summarized. Originally inspired from research into model based diagnosis, work on multiple model identification evolved into a methodology for probabilistic model falsification. Throughout the research, parallel studies developed strategies for measurement system design. Recent comparisons with Bayesian model updating have shown that while traditional applications Bayesian methods are precise and accurate when all is known, they are not robust in the presence of approximate models. Finally, details of the full-scale case studies that have been used to develop model falsification are briefly described. The model-falsification strategy for data interpretation provides engineers with an easy-to-understand tool that is compatible with the context of the built environment

Conditions for Growth and Retreat of the Laurentide Ice Sheet

Results of three dimensional numerical modelling of the North American ice sheets in response to the Earth's orbital radiation variations are reviewed in relation to the conditions for formation and retreat of the ice sheets. The last interglacial develops as a clear result of the preceding high summer radiation levels and is not very dependent on the climatic paramaterisation. The magnitude and timing of the last glacial maximum provides a means of fine tuning the climatic parameterisation. In between these two periods the extent of ice sheet advances and retreat is strongly sensitive to the magnitude of the ice sheet albedo feedback parameter. The time changes of the radiation, climate, ice sheet cover and bedrock depression are out of phase and as a result equilibrium is not attained. The distribution of land surface elevation plays a key role in the pattern of seeding of the ice sheet growth and the subsequent advances, coalescence and retreat. The dispersal pattern of bedrock in till can be expected to reflect the growth and advance phases of the ice sheet development rather than the maximum configuration. Finally, the cycles of ice ages over the last 500,000 years from the modelling follows the occurrence of extreme summer radiation levels over a wide latitude band of 40-80°N due to coincidence of obliquity and perihelion features superimposed on the hysteresis effects of the ice cover.Les résultats obtenus à partir de la modélisation numérique tri-dimensionnelle des calottes glaciaires de l'Amérique du Nord selon les variations de l'insolation des latitudes sont examinés en fonction des conditions à l'origine de la formation et du retrait des inlandsis. L'existence du dernier interglaciaire est nettement le résultat des hauts niveaux antérieurs d'insolation estivale et très peu celui des paramètres climatiques. L'ampleur et la durée du dernier maximum glaciaire permettent de préciser les paramètres climatiques en cause. Entre ces deux périodes, l'importance de la progression des glaciers et de leur retrait subséquent est grandement influencée par l'albédo de la calotte glaciaire. Les changements temporels de l'insolation, du climat, de la couverture de glace et de l'enfoncement du substratum sont décalés les uns par rapport aux autres, résultant en un déséquilibre. La répartition des altitudes de la surface terrestre joue un rôle clé dans le processus de formation de la calotte glaciaire, ainsi que des récurrences, de la coalescence et du retrait subséquents. On peut s'attendre à ce que le mode de dispersion des dépôts glaciaire expriment davantage les phases de croissance et de récurrence de la calotte glaciaire que sa configuration maximale. En dernier lieu selon le modèle, les cycles de glaciation au cours des 500 000 dernières années suivent l'apparition de niveaux extrêmes d'insolation le long d'une large bande de 40° à 80° de latitude, en raison de l'obliquité de l'écliptique et des caractéristiques du périhélie surimposés à l'effet d'hystéréris causé par la couverture de glace.Die Ergebnisse eines dreidimensionalen numerischen Modells der nordamerikanischen Eisdecken entsprechend den Variationen der Sonneneinstrahlung in verschiedenen Breiten werden in Bezug auf die Bedingungen fur die Bildung und den Riickzug der Eisdecken untersucht. Die letzte Interglazialzeit ist eine klare Folge der vorhergehenden hohen sommerlichen Sonneneinstrahlungen und ist nicht sehr abhângig von den klimatischen Parametern. Der Umfang und die Dauer des letzten glazialen Maximums erlauben die klimatischen Parameter genau zu bestimmen. Zwischen diesen beiden Perioden war der Umfang des Vorrückens und Rückzugs der Eisdecke stark beeinflupt vom Umfang der Albedo-Parameter der Eisdecke. Die zeitlichen Wechsel der Sonneneinstrahlung, des Klimas, der Eisdecke und der Senkung des Landes sind nicht phasengleich, und so wird kein Gleichgewicht erreicht. Die Verteilung der Erdoberflächenerhebungen nimmt eine Schlüsselrolle ein in dër Verteilung des Wachsens der Eisdecke und den darauf folgenden Rückphasen, dem Zusammenwachsen und dem Rückzug. Es ist anzunehmen, dap die Art der Verteilung des Landes in der Grundmoräne eher das Anwachsen und die VorstoBphasen der Eisdecke spiegelt als ihre maximale Gestalt. Zuletzt entsprechen dem Modell nach die Zyklen der Vereisung während der letzten 500,000 Jahre dem Vorkommen extremer sommerlicher Sonneneinstrahlung entlang eines breiten Gùrtels von 40-80o nördlicher Breite, infolge der Übereinstimmung von Neigungswinkel und Charakteristika der Sonnennähe, überlagert durch die Hysteresis-Wirkungen der Eisdecke

Innovative 3D and 2D machine vision methods for analysis of plants and crops in the field

© 2018 Elsevier B.V. Machine vision systems offer great potential for automating crop control, harvesting, fruit picking, and a range of other agricultural tasks. However, most of the reported research on machine vision in agriculture involves a 2D approach, where the utility of the resulting data is often limited by effects such as parallax, perspective, occlusion and changes in background light – particularly when operating in the field. The 3D approach to plant and crop analysis described in this paper offers potential to obviate many of these difficulties by utilising the richer information that 3D data can generate. The methodologies presented, such as four-light photometric stereo, also provide advanced functionalities, such as an ability to robustly recover 3D surface texture from plants at very high resolution. This offers potential for enabling, for example, reliable detection of the meristem (the part of the plant where growth can take place), to within a few mm, for directed weeding (with all the associated cost and ecological benefits) as well as offering new capabilities for plant phenotyping. The considerable challenges associated with robust and reliable utilisation of machine vision in the field are also considered and practical solutions are described. Two projects are used to illustrate the proposed approaches: a four-light photometric stereo apparatus able to recover plant textures at high-resolution (even in direct sunlight), and a 3D system able to measure potato sizes in-the-field to an accuracy of within 10%, for extended periods and in a range of environmental conditions. The potential benefits of the proposed 3D methods are discussed, both in terms of the advanced capabilities attainable and the widespread potential uptake facilitated by their low cost

A study of two stochastic search methods for structural control

Abstract: Many engineering tasks involve the search for good solutions among many possibilities. In most cases, tasks are too complex to be modeled completely and their solution spaces often contain local minima. Therefore, classical optimization techniques cannot, in general, be applied effectively. This paper studies two stochastic search methods, one well-established �simulated annealing � and one recently developed �probabilistic global search Lausanne�, applied to structural shape control. Search results are applied to control the quasistatic displacement of a tensegrity structure with multiple objectives and interdependent actuator effects. The best method depends on the accuracy related to requirements defined by the objective function and the maximum number of evaluations that are allowed

Combining dynamic relaxation method with artificial neural networks to enhance simulation of tensegrity structures

Abstract: Structural analyses of tensegrity structures must account for geometrical nonlinearity. The dynamic relaxation method correctly models static behavior in most situations. However, the requirements for precision increase when these structures are actively controlled. This paper describes the use of neural networks to improve the accuracy of the dynamic relaxation method in order to correspond more closely to data measured from a full-scale laboratory structure. An additional investigation evaluates training the network during the service life for further increases in accuracy. Tests showed that artificial neural networks increased model accuracy when used with the dynamic relaxation method. Replacing the dynamic relaxation method completely by a neural network did not provide satisfactory results. First tests involving training the neural network online showed potential to adapt the model to changes during the service life of the structure. DOI: 10.1061/�ASCE�0733-9445�2003�129:5�672