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1.
Highly degenerate primers to conserved regions of the eukaryotic phosphoinositol-specific phospholipase C (PLC) were used to amplify fragments of plant PLCs from Arabidopsis thaliana genomic DNA. Eight completely different fragment sequences that showed high homology to PLCs of both animals and plants were isolated. The variation between these putative PLCs was high and suggests that, like animals, plants have multiple isoforms of PLC. Using one of the PCR clones, we isolated a corresponding full-length Arabidopsis PLC gene (ATHATPLC1G), and sequence analysis indicated that it was most like a delta-type PLC. This gene is 2.5 kb and contains seven introns, all but one of which has intron/exon border sequences that conform to the Arabidopsis consensus. The structural complexity of the gene is relatively simple compared to mammalian beta-type PLCs that can be 15 kb long with up to 30 introns. The plant gene is a single copy and was mapped to four Arabidopsis YACs, one located on chromosome 2. The promoter region contained two TATA-like elements at -43 and -185 and other putative regulatory elements that suggest that this PLC is hormonally regulated. This is the first plant PLC gene and the first delta type-PLC gene from a higher organism to be sequenced.  相似文献   
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In DS-WCDMA mobile systems such the UMTS, asynchronous cell site operation,assigning different long spreading code to each cell, yields the advantageof flexible system deployment. We can design an indoor system basedon an outdoor one. However, in general, much longer search time isrequired in asynchronous operation than in synchronous. This paperproposes three techniques to take decisions about synchronizationbased on observation of correlated signals. Classical decision criterialike maximum and threshold criterion are presented. A new decisioncriteria that we call Threshold&Max combined decision criteriais analyzed. The results of this new introduced technique is comparedwith the classical ones.  相似文献   
4.
Energy-efficient video streaming over Bluetooth using rateless coding   总被引:1,自引:0,他引:1  
Razavi  R. Fleury  M. Ghanbari  M. 《Electronics letters》2008,44(22):1309-1310
Energy-efficient error control for IEEE 802.15.1 (Bluetooth) video communication is proposed. The scheme is based on block-oriented incremental redundancy provided by rateless coding and receiver feedback. Results are presented for time-sensitive video streaming applications under a Markovian channel model. When the proposed algorithm is compared to variations of Bluetooth forward error control, there are improvements of around 3 dB in received video quality and of over 10% in energy efficiency.  相似文献   
5.
Rate constants for the reversible deprotonation of acetylacetone were measured in carboxylate and amine buffers in water and in 50%, 90% and 95% Me2SO at 20°C. The Brønsted plot for the carboxylate ions is curved in the Me2SO—water mixtures, but straight in water. The curvature is in the direction predicted by the Reactivity—Selectivity Principle (RSP). However, the Brønsted plot for the reaction with primary amines is straight in all solvents. This suggests that the curvature observerd with the carboxylate ions is caused by loss of solvation of the base; this loss of solvation is ahead of bond formation in the transition state rather than being a manifestation of the RSP. (Note that all Brønsted plots are based on pKa values measured in the respective solvents.) The intrinsic rate constant (k0) for proton transfer increases with the addition of Me2SO, and more so with the carboxylate buffers than with the amines. This increase in k0 is attributed to delayed solvation of the developing enolate ion in the transition state; with the carboxylate buffers, an additional factor is the early loss of solvation of the base. The various solvation effects observed in this study can all be understood in the context of the Principle of Imperfect Synchronization (PIS).  相似文献   
6.
Subcontinuations     
Continuations have proven to be useful for implementing a variety of control structures, including exception handling facilities and breadth-first searching algorithms. However, traditional continuations are not useful in the presence of concurrency, because the notion of the rest of the computation represented by a continuation does not in general make sense. Traditional continuations can also be difficult to use in nonconcurrent settings, since their global nature is sometimes problematic. This article presents a new type of continuation, called asubcontinuation. Just as a traditional continuation represents the rest of a computation ¿from a given point in the computation, a subcontinuation represents the rest of asubcomputation ¿from a given point in the subcomputation. Subcontinuations may be used to control tree-structured concurrency by allowing nonlocal exits to arbitrary points in a process tree and allowing the capture of a subtree of a computation as a composable continuation for later use. In the absence of concurrency the localized control achievable with subcontinuations makes them more useful than traditional continuations.  相似文献   
7.
Osmotic pressure measurements were satisfactorily used to compute the effective charge of poly(acrylic) acid (PAA) at different pHs and with different monovalent and divalent counterions. This experimental method is sensitive to the osmotically active species (polymer and counterions). After correction for the polymer contribution to the total osmotic pressure (solvency and excluded volume), the remaining pressure can be attributed to the polyelectrolyte counterions and processed with Donnan and equation of state in order to compute the effective charge number per polymeric chain (Zeff). The behavior of Zeff against the chain concentration and pH was investigated after neutralization of PAA with LiOH, NaOH, and TMAOH. The results clearly indicate that the nature of the monovalent counterion has no effect on Zeff leading to the conclusion that the interaction between monovalent counterions and the acrylate functionality is purely electrostatic in agreement with conductimetric and potentiometric results reported in the literature. The behavior of Zeff against the degree of ionization of the polymer and its concentration is also in good agreement with the theoretical expectations of the theory of ionic condensation. Osmotic measurements were also used in order to understand the influence of divalent cations (Mg2+, Ca2+, Ba2+) on Zeff of the sodium salt of PAA at pH 9 and at different divalent/acrylate molar ratio. All the divalent cations depress Zeff each of one at different degrees, confirming a specific divalent/polymer interaction. The energy of hydration of cations can explain most of the observed results with divalents.  相似文献   
8.
The Na2O-Cs2O-SiO2 system has been investigated by means of a new differential thermal analysis apparatus. Two compounds have been observed for the first time in the metasilicate and disilicate joins. The CsNaSi2O5 disilicate melts congruently at 1217 K and the peritectic fusion of the CsNaSiO3 metasilicate occurs at 1120 K.  相似文献   
9.
During the 1974–2004 period, the sleep literature had quadrupled (2384 publications in 1974, and 9721 in 2004) while overall scientific productivity had only doubled. The set of the seven most productive countries (USA, Japan, United Kingdom, Germany, France, Canada and Italy) in sleep research, and the geographical region distribution remained stable over the three decades. On the other hand several indicators appeared in the sleep research literature during the 1990s: the increasing productivity of sleep researchers; the growing number of countries publishing on sleep; the continuous creation of sleep-focused journals; the scattering of sleep publication among increasingly more scientific journals; the turnover among the leading journals; and the emergence of new entities such as China, Turkey, and the European Union.  相似文献   
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