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Geometric Pattern (geometric + pattern)
Selected AbstractsExperimental Physiology ,Review Article: Tissue capillary supply , it's quality not quantity that counts!EXPERIMENTAL PHYSIOLOGY, Issue 10 2010Stuart Egginton This article explores how common misunderstandings about the microcirculation , that capillary supply varies directly with O2 demand, that local capillary supply in muscle is determined by fibre type and that it is appropriate to model capillary distribution as either random or in a fixed geometric pattern , arise from quantifying capillarity by simple measures of quantitative extent, rather than the more functionally relevant qualitative distribution. We show that the latter approach reveals exquisite control of angiogenesis that determines the location of new vessels with astonishing accuracy, motivating a reappraisal of the physiological remodelling process and a new approach to computational investigations into peripheral O2 transport. [source] Formation of a geometric pattern with a mobile wireless sensor networkJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 10 2004Justin Lee Mobile wireless sensor networks (MWSNs) will enable information systems to gather detailed information about the environment on an unprecedented scale. These self-organizing, distributed networks of sensors, processors, and actuators that are capable of movement have a broad range of potential applications, including military reconnaissance, surveillance, planetary exploration, and geophysical mapping. In many of the foreseen applications, the MWSN will need to form a geometric pattern without assistance from the user. In military reconnaissance, for example, the nodes will be dropped onto the battlefield from a plane and land at random positions. The nodes will be expected to arrange themselves into a predetermined formation in order to perform a specific task. Thus, we present algorithms for forming a line, circle, and regular polygon from a given set of random positions. The algorithms are distributed and use no communication between the nodes to minimize energy consumption. Unlike past studies of geometric problems where algorithms are either tested in simulations where each node has global knowledge of all the other nodes or implemented on a small number of robots, the robustness of our algorithms has been studied with simulations that model the sensor system in detail. The simulations demonstrate that the algorithms are robust against random errors in the sensors and actuators. © 2004 Wiley Periodicals, Inc. [source] Structure and hydrogen bonding in 2,4-dihydroxybenzoic acid at 90, 100, 110 and 150,K; a theoretical and single-crystal X-ray diffraction studyACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2007Andrew Parkin A new polymorph of 2,4-dihydroxybenzoic acid is reported. The structure was characterized by multiple-temperature X-ray diffraction and solid-state DFT computations. The material shows a geometric pattern of hydrogen bonding consistent with cooperativity between the intermolecular carboxylic acid dimer and intramolecular hydrogen bonds. The presence of proton disorder within this hydrogen-bond system, which would support such a cooperative model, was not fully ruled out by the initial X-ray studies. However, solid-state calculations on the three possible end-point tautomers indicate that the dominant crystallographically observed configuration is substantially lower in energy than the other tautomers (by at least 9,kJ,mol,1), indicating that no disorder should be expected. It is therefore concluded that no disorder is observed either in the intra- or intermolecular hydrogen bonds of the title compound and that the cooperativity between the hydrogen bonds is not present within the temperature range studied. [source] Overestimation of Left Ventricular Mass and Misclassification of Ventricular Geometry in Heart Failure Patients by Two-Dimensional Echocardiography in Comparison with Three-Dimensional EchocardiographyECHOCARDIOGRAPHY, Issue 3 2010Dmitry Abramov M.D. Background: Accurate assessment of left ventricular hypertrophy (LVH) and ventricular geometry is important, especially in patients with heart failure (HF). The aim of this study was to compare the assessment of ventricular size and geometry by 2D and 3D echocardiography in normotensive controls and among HF patients with a normal and a reduced ejection fraction. Methods: One hundred eleven patients, including 42 normotensive patients without cardiac disease, 41 hypertensive patients with HF and a normal ejection fraction (HFNEF), and 28 patients with HF and a low ejection fraction (HFLEF), underwent 2DE and freehand 3DE. The differences between 2DE and 3DE derived LVM were evaluated by use of a Bland,Altman plot. Differences in classification of geometric types among the cohort between 2DE and 3DE were determined. Results: Two-dimensional echocardiography overestimated ventricular mass compared to 3D echocardiography (3DE) among normal (166 ± 36 vs. 145 ± 20 gm, P = 0.002), HFNEF (258 ± 108 vs. 175 ± 47gm, P < 0.001), and HFLEF (444 ± 136 vs. 259 ± 77 gm, P < 0.001) patients. The overestimation of mass by 2DE increased in patients with larger ventricular size. The use of 3DE to assess ventricular geometry resulted in reclassification of ventricular geometric patterns in 76% of patients with HFNEF and in 21% of patients with HFLEF. Conclusion: 2DE overestimates ventricular mass when compared to 3DE among patients with heart failure with both normal and low ejection fractions and leads to significant misclassification of ventricular geometry in many heart failure patients. (Echocardiography 2010;27:223-229) [source] Coupled axial,radial segregation in rotating drums with high fill levelsAICHE JOURNAL, Issue 7 2006H. P. Kuo Axial segregation and radial segregation within the granular bed in a rotating drum with a fill level > 50% were experimentally investigated. The axial segregated patterns and the radial segregated patterns were coupled within the bed, resulting in observation of new segregated patterns at the plane along the rotational shaft. The segregated patterns are different from the previous axial band and radial core patterns and show coupled new patterns, including the "cross" patterns, the "band-core-in-core" patterns, and other geometric patterns. The new segregation patterns are strong functions of the fill level and the rotational speed of the drum. The formation of the axial,radial coupled patterns was attributed to the fill level, the free flowing surface of the bed. A virtual drum hypothesis is proposed to explain the formation of the complex segregated patterns. © 2006 American Institute of Chemical Engineers AIChE J, 2006 [source] Compression-Inhibited Pore Formation of Polyelectrolyte Multilayers Containing Weak Polyanions: A Scanning Force Microscopy StudyCHEMPHYSCHEM, Issue 3 2006Bo Wang Abstract Morphological changes of poly(acrylic acid)/poly(diallyldimethylammonium chloride) multilayers induced by low pH were investigated by scanning force microscopy. The weakened interaction between the charged polymer chains in the protonation process is believed to be the reason for this variation. Kinetic studies have shown that during protonation phase separation and dissociation of the multilayers took place successively. The compression of the multilayers, however, caused a transition of the multilayers from a rubbery state to a glassy state. As a result, the closely compacted multilayers lost their sensitivity to pH change. An increase of electrostatic and hydrophobic interactions, can decrease the free energy of the multilayers, and stabilize the films. By compression of the multilayers with a rubber stamp having geometric patterns, films with spatially localized pores were produced. [source] | ||||||||||