Home About us Contact
|
Home About us Contact | ||
|
|
||
Active Modes (active + mode)
Selected AbstractsDynamic power management in new architecture of wireless sensor networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 6 2009Chuan Lin Abstract Dynamic power management (DPM) technology has been widely used in sensor networks. Though many specific technical challenges remain and deserve much further study, the primary factor currently limiting progress in sensor networks is not these challenges but is instead the lack of an overall sensor network architecture. In this paper, we first develop a new architecture of sensor networks. Then we modify the sleep state policy developed by Sinha and Chandrakasan in (IEEE Design Test Comput. 2001; 18(2):62,74) and deduce that a new threshold satisfies the sleep-state transition policy. Under this new architecture, nodes in deeper sleep states consume lower energy while asleep, but require longer delays and higher latency costs to awaken. Implementing DPM with considering the battery status and probability of event generation will reduce the energy consumption and prolong the whole lifetime of the sensor networks. We also propose a new energy-efficient DPM, which is a modified sleep state policy and combined with optimal geographical density control (OGDC) (Wireless Ad Hoc Sensor Networks 2005; 1(1,2):89,123) to keep a minimal number of sensor nodes in the active mode in wireless sensor networks. Implementing dynamic power management with considering the battery status, probability of event generation and OGDC will reduce the energy consumption and prolong the whole lifetime of the sensor networks. Copyright © 2008 John Wiley & Sons, Ltd. [source] Glucocorticoids maintain human osteoclasts in the active mode of their resorption cycleJOURNAL OF BONE AND MINERAL RESEARCH, Issue 10 2010Kent Sře Abstract Osteoclasts are known to exert their resorptive activity through a so-called resorption cycle consisting of alternating resorption and migration episodes and resulting typically in the formation of increasing numbers of discrete round excavations on bone slices. This study shows that glucocorticoids deeply modify this resorptive behavior. First, glucocorticoids gradually induce excavations with a trenchlike morphology while reducing the time-dependent increase in excavation numbers. This indicates that glucocorticoids make osteoclasts elongate the excavations they initiated rather than migrating to a new resorption site, as in control conditions. Second, the round excavations in control conditions contain undegraded demineralized collagen as repeatedly reported earlier, whereas the excavations with a trenchlike morphology generated under glucocorticoid exposure appear devoid of leftovers of demineralized collagen. This indicates that collagenolysis proceeds generally at a lower rate than demineralization under control conditions, whereas collagenolysis rates are increased up to the level of demineralization rates in the presence of glucocorticoids. Taking these observations together leads to a model where glucocorticoid-induced increased collagenolysis allows continued contact of osteoclasts with mineral, thereby maintaining resorption uninterrupted by migration episodes and generating resorption trenches. In contrast, accumulation of demineralized collagen, as prevails in controls, acts as a negative-feedback loop, switching resorptive activity off and promoting migration to a new resorption site, thereby generating an additional resorption pit. We conclude that glucocorticoids change the osteoclastic resorption mode from intermittent to continuous and speculate that this change may contribute to the early bone fragilization of glucocorticoid-treated patients. © 2010 American Society for Bone and Mineral Research. [source] Functionally distinct haemoglobins of the cryopelagic Antarctic teleost Pagothenia borchgrevinkiJOURNAL OF FISH BIOLOGY, Issue 2000A. Riccio Pagothenia borchgrevinki, has a higher haemoglobin concentration than other Antarctic notothenioids and the high oxygen capacity may correlate with the relatively active mode of life of this fish. The fish has five haemoglobins (Hb C, Hb 0, Hb 1, Hb 2 and Hb 3) with Hb 1 accounting for 70,80% of the total, and Hb C being present in trace amounts. Hb 1 and Hb 2 are functionally similar in terms of Bohr and Root effects. Hb 3 has a weaker Bohr effect than Hb 1 and Hb 2, and the Root effect is similar to that of Hb 1. Hb 0 has a strong Bohr effect and the Root effect is enhanced to a larger extent by the physiological effectors chlorides and phosphates than that of the other components with the exception of Hb C. The heats of oxygenation are lower than those of temperate fish haemoglobins. Temperature variations may have a different effect on the functional properties of each haemoglobin, and chloride and phosphates may play an important role in the conformational change between the oxy and deoxy structures. The complete amino acid sequences of Hb 1 and Hb 0, as well as partial N-terminal or internal sequences of the other haemoglobins, have been established. The high multiplicity of functionally distinct haemoglobins indicates that P. borchgrevinki, has a specialized haemoglobin system. [source] Temperature-Dependent Optical Reflectivity of Tetragonal-Prime Yttria-Stabilized ZirconiaJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2006John A. Nychka The optical reflectance of dense, metastable, tetragonal-prime zirconia plates, made by densifying electron beam physical vapor-deposited powder, is reported as a function of temperature up to 1673 K (1400°C) over the range of 400,1500 cm,1 (6.67,25 ,m). Curve fitting of the reflectance as a function of temperature was performed using two different damped oscillator models, each with three infrared (IR)-active modes. Oscillator parameters were then used to calculate the values of the indices of refraction and absorption as a function of temperature using the classical dispersion theory. The reflectance data of tetragonal-prime yttria-stabilized zirconia at room temperature are qualitatively similar to that reported for the equilibrium tetragonal phase in that it can be fit with three IR-active modes. [source] High pressure Raman study of BaMoO4PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 14 2004D. Christofilos Abstract The structural stability of polycrystalline BaMoO4 under hydrostatic pressure has been investigated by means of Raman spectroscopy up to 8 GPa. Raman spectra reveal a pressure induced phase transition at ,5.8 GPa. Upon pressure release the structure reverts to its ambient pressure scheelite (CaWO4) structure with no observable hysteresis. The large number of Raman active modes of the high pressure phase suggests either an increase of the size of the unit cell and/or a non-centrosymmetric structure leading to the activation of the ungerade modes of the scheelite structure. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A new adaptive backstepping Coulomb friction compensator for servo control systems,ASIAN JOURNAL OF CONTROL, Issue 1 2009Jen-te Yu Abstract A new Coulomb friction compensator is proposed for servo control systems in this paper. The novelty of the new approach lies in its capability of assigning the eigenvalues of the resulting closed loop system while attacking the problem. First, based on the standard backstepping methodology, an implicit Lyapunov function, with part of the components being only symbolically constructed at the very beginning, is utilized. To increase the robustness of the system against disturbance and model inaccuracy, an integral term is employed in the design. Using part of the variable gradient method, we are able to turn the implicit Lyapunov function into an explicit one, which is positive definite, and whose time-derivative is negative definite. Second, it will be shown that the resulting closed loop error system is a switched linear system with two possible active modes that share the same set of eigenvalues, which is at our disposal. Unlike the common adaptive control design methods, such as the Control Lyapunov Function approach, in which the gains are typically positive but otherwise arbitrary, and are hence difficult to choose and have a lack of connection with the system's performance, our new scheme imposes two further constraints on the gains. It turns out that we can then match these gains with the coefficients of the desired characteristic equation of the closed loop system. In this respect, the gains are linked to the system's overall performance, which is a new and very appealing feature for such a scheme. Finally, a procedure of constructing a common Lyapunov function is provided to prove exponential stability of the aforementioned switched linear system. In addition, using the invariance principle, we will show the convergence of the estimated Coulomb friction coefficient to its real value. Numerical simulations are given to validate the effectiveness of the design and its robustness against friction time-variations. Compared to existing results, the proposed scheme is much simpler, hence, much more advantageous computationally. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] Reduction of a set of elementary modes using yield analysisBIOTECHNOLOGY & BIOENGINEERING, Issue 2 2009Hyun-Seob Song Abstract This article proposes a new concept termed "yield analysis" (YA) as a method of extracting a subset of elementary modes (EMs) essential for describing metabolic behaviors. YA can be defined as the analysis of metabolic pathways in yield space where the solution space is a bounded convex hull. Two important issues arising in the analysis and modeling of a metabolic network are handled. First, from a practical sense, the minimal generating set spanning the yield space is recalculated. This refined generating set excludes all the trivial modes with negligible contribution to convex hull in yield space. Second, we revisit the problem of decomposing the measured fluxes among the EMs. A consistent way of choosing the unique, minimal active modes among a number of possible candidates is discussed and compared with two other existing methods, that is, those of Schwartz and Kanehisa (Schwartz and Kanehisa, 2005. Bioinformatics 21: 204,205) and of Provost et al. (Provost et al., 2007. Proceedings of the 10th IFAC Symposium on Computer Application in Biotechnology, 321,326). The proposed idea is tested in a case study of a metabolic network of recombinant yeasts fermenting both glucose and xylose. Due to the nature of the network with multiple substrates, the flux space is split into three independent yield spaces to each of which the two-staged reduction procedure is applied. Through a priori reduction without any experimental input, the 369 EMs in total was reduced to 35 modes, which correspond to about 91% reduction. Then, three and four modes were finally chosen among the reduced set as the smallest active sets for the cases with a single substrate of glucose and xylose, respectively. It should be noted that the refined minimal generating set obtained from a priori reduction still provides a practically complete description of all possible states in the subspace of yields, while the active set covers only a specific set of experimental data. Biotechnol. Bioeng. 2009;102: 554,568. © 2008 Wiley Periodicals, Inc. [source] Characteristics of adult dentally fearful individuals.EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 4 2000A cross-cultural study This cross-cultural study investigated adult dental fear patients in three countries. A joint intake interview questionnaire and a dental anxiety scale explored the level, background and concomitant factors of dental anxiety among patients at the Universities of Tel Aviv (Israel), Göteborg (Sweden), and Pittsburgh (USA). It was shown that patients at all three sites were quite similar with regard to age, sex, level of dental anxiety (DAS) and avoidance time. Negative emotions were common, with more negative everyday life effects among Swedish patients. Regardless of country, most patients stated that they had always been fearful, but environmental etiologic factors were frequently reported. Swedish patients more often reported both direct and indirect learning patterns than Israeli patients. Patients' motivation for treatment was high, while the belief in getting fear reduction was clearly lower. The most common reason for Israeli patients to seek treatment was a personal decision to try to cope with the situation, while for Swedish patients it was pain. Israeli and US patients preferred more ,active' modes of treatment such as behavioral management therapies, while Swedish patients equally preferred active and more ,passive' treatment approaches such as general anesthesia. Preference for dentist attributes were similar among groups and underlined the strong emphasis that fearful individuals place upon dentists' behaviors and their performance of dentistry. [source] | |||||||||||||