Efficient Block Scheduling to Minimize Context Switching Time for Programmable Embedded Processors

Scheduling is one of the most often addressed optimization problems in DSP compilation, behavioral synthesis, and system-level synthesis research. With the rapid pace of changes in modern DSP applications requirements and implementation technologies, however, new types of scheduling challenges arise. This paper is concerned with the problem of scheduling blocks of computations in order to optimize the efficiency of their execution on programmable embedded systems under a realistic timing model of their processors. We describe an effective scheme for scheduling the blocks of any computation on a given system architecture and with a specified algorithm implementing each block. We also present algorithmic techniques for performing optimal block scheduling simultaneously with optimal architecture and algorithm selection. Our techniques address the block scheduling problem for both single- and multiple-processor system platforms and for a variety of optimization objectives including throughput, cost, and power dissipation. We demonstrate the practical effectiveness of our techniques on numerous designs and synthetic examples.     

The Role of Titanium Dioxide on the Hydration of Portland Cement: A Combined NMR and Ultrasonic Study

Titanium dioxide (TiO₂) is an excellent photocatalytic material that imparts biocidal, self-cleaning and smog-abating functionalities when added to cement-based materials. The presence of TiO₂ influences the hydration process of cement and the development of its internal structure. In this article, the hydration process and development of a pore network of cement pastes containing different ratios of TiO₂ were studied using two noninvasive techniques (ultrasonic and NMR). Ultrasonic results show that the addition of TiO₂ enhances the mechanical properties of cement paste during early-age hydration, while an opposite behavior is observed at later hydration stages. Calorimetry and NMR spin–lattice relaxation time T₁ results indicated an enhancement of the early hydration reaction. Two pore size distributions were identified to evolve separately from each other during hydration: small gel pores exhibiting short T₁ values and large capillary pores with long T₁ values. During early hydration times, TiO₂ is shown to accelerate the formation of cement gel and reduce capillary porosity. At late hydration times, TiO₂ appears to hamper hydration, presumably by hindering the transfer of water molecules to access unhydrated cement grains. The percolation thresholds were calculated from both NMR and ultrasonic data with a good agreement between both results.     

Effects of temperature,pH, and ionic strength on the adsorption of nanoparticles at liquid–liquid interfaces

The effects of temperature, pH and sodium chloride (NaCl) concentration on the equilibrium and dynamic interfacial tension (IFT) of 4.4-nm gold nanoparticles capped with n-dodecanethiol at hydrocarbon–water interfaces was studied. The pendant drop technique was used to study the adsorption properties of these nanoparticles at the hexane–water and nonane–water interfaces. The physical size of the gold nanoparticles was determined by TEM image analysis. The interfacial properties of mixtures of these nanoparticles, having different sizes and capping agents, were then studied. The addition of NaCl was found to cause a decrease of the equilibrium and dynamic IFT greater than that which accompanies the adsorption of nanoparticles at the interface in the absence of NaCl. Although IFT values for acidic and neutral conditions were found to be similar, a noticeable decrease in the IFT was found for more basic conditions. Increasing the temperature of the system was found to cause an increase in both dynamic and equilibrium IFT values. These findings have implications for the self-assembly of functionalized gold nanoparticles at liquid–liquid interfaces.     

NMR Spectral Data of Benzofurans and Bithiophenes from Hairy Root Cultures of Tagetes Patula Andthe Molecular Structure of Isoeuparin

In the course of our biosynthetic studies of constituents of hairy root cultures of Tagetes patula, we isolated four bithiophenes,[5-(3-buten-1-yny1)]-2,2′-bithiophenes(BBT),5-(4-acetoxy-1-butyny1)-2,2′-bithiophenes (BBTOAc),5-(4-hydroxy-1-butyny1)-2,2′bithiophenes (BBTOH) and 5-(3,4-diacetoxy-1-butyny1)-2,2′-bithiophenes [BBT(OAc)2]. In addition, stigmasterol, α-farnesene, three known benzofurans, of which only one was previouly isolated from T.patula, as well as a new benzofuran were obtained. The structures of the componds were determined by spectral analysis and comparison with published data. The molecular structure of the benzofuran isoeuparin was established by single crystal x-ray diffraction.     

Cross-linguistic studies of children's and adults' vowel spaces

This study examines cross-linguistic variation in the location of shared vowels in the vowel space across five languages (Cantonese, American English, Greek, Japanese, and Korean) and three age groups (2-year-olds, 5-year-olds, and adults). The vowels /a/, /i/, and /u/ were elicited in familiar words using a word repetition task. The productions of target words were recorded and transcribed by native speakers of each language. For correctly produced vowels, first and second formant frequencies were measured. In order to remove the effect of vocal tract size on these measurements, a normalization approach that calculates distance and angular displacement from the speaker centroid was adopted. Language-specific differences in the location of shared vowels in the formant values as well as the shape of the vowel spaces were observed for both adults and children.     

One-pot regioselective synthesis and X-ray crystal structure of a stable [60]fullerene trisadduct with the e(edge),e(face),trans-1 addition pattern

The Bingel functionalisation of C(60) with a structurally novel tether equipped with three reactive malonate groups afforded a C(2v)-symmetrical e(edge),e(face),trans-1 trisadduct in a complete regioselective manner and in an excellent yield of 65%. The [60]fullerene trisadduct showed pronounced ability to crystallise and gave X-ray quality single crystals for analysis.     

Retention of structurally diverse drugs in human serum albumin chromatography and its potential to simulate plasma protein binding

The retention behavior of 39 structurally diverse neutral, basic and acidic drugs was investigated on an HSA stationary phase using PBS buffer (pH 7.0) and acetonitrile or 2-propanol as organic modifiers. Extrapolated or directly measured log k_w values as well as isocratic retention factors were correlated with plasma protein binding data taken from the literature. Retention factors determined in the presence of 10% acetonitrile led to high quality 1:1 correlation with apparent log K_HSA values. The derived reference equation was successfully validated using a secondary set of 24 drugs. Further analysis of HSA retention into more fundamental properties revealed the involvement of anionic species in solute-stationary phase interactions, expressed by the negatively charged fraction, besides the partitioning mechanism which was reflected by lipophilicity. Protonation of basic drugs, although less important, may also influence retention, leading to reduced partitioning into the HSA surface as a net effect, while it seems to have no effect on HSA binding. The above results were further confirmed by linear solvation energy relationships (LSER).     

Sesquiterpenes from Chrysoma Pauciflosculosa

Abstract

The aerial parts of Chrysoma pauciflosculosa (syn. Solidago pauciflosculosa) gave two new sesquiterpenes, (+)-β-turmerone and a bisabolane endoperoxide, together with the known (-)-α-trans-bergamotene and (+)-β-sesquiphellandrene. When exposed to air and light, (+)-β-turmerone and (+)-β-sesquiphellandrene gave oxidative degradation products, involving hydroperoxide intermediates. Photosensitized singlet oxygen reactions of (+)-β-turmerone provided a series of bisabolane-type endoperoxides. The structures of the natural compounds as well as those of the degradation products and derivatives were elucidated by chemical and spectroscopic methods, mainly NMR and MS. Aqueous solutions of (+)-β-turmerone,(+)-β-sesquiphellandrene and (-)-α-trans-bergamotene were tested for their effects on the germination and radicle growth of three Florida sandhill species, Rudbeckia hirta, Schizachyrium scoparium, Leptochloa dubia, as well as Lactuca sativa. (+)-β-Turmerone significantly inhibited germination of L. sativa, stimulated radicle growth of L. sativa and S. scoparium at the 10^?4 M level, and mildly inhibited radicle growth of R. hirta, as did (+)-β-sesquiphellandrene. (-)-α-trans-Bergamotene stimulated germination of S. scoparium and L. sativa and significantly enhanced radicle growth of S. scoparium.     

An analytical model for the determination of the cup-burner minimum extinguishing concentration of inert fire suppression agents

An analytical model based on the perfectly stirred reactor (PSR) concept is developed and utilized in the prediction of the minimum extinguishing concentration (MEC) of inert fire suppression agents that is established in the standard cup-burner test. In the PSR-based approach, both thermal (heat absorption) and chemical mechanisms of fire suppression can be captured. The assumed perfect mixing, on the other hand, prevents the ability to capture transport related mechanisms. In past work, the PSR approach using detailed chemistry was demonstrated to be effective in reproducing the MEC albeit with the need of single point calibration. The closed form solution presented herein becomes possible when the detailed chemistry is simplified to a single step, mole preserving chemical reaction. At the core of the model is an analytical expression for the extinction temperature which is transcendental and thus requires a numerical iterative solution. The analytical model is first verified using a traditional computational PSR (CHEMKIN package) that employs the same reduced kinetics as the analytical model. Subsequently, results from the analytical model are contrasted to those from a traditional PSR with detailed chemistry, from a semi-analytical approach that assumes heat absorption by the agent is the primary extinguishing mechanism, and from experimental data of various research groups. Good agreement is achieved validating the analytical model as a simple and accurate approach to determine the MEC. The analytical model is also used in a parametric assessment of the impact of geographic altitude (i.e. effect of ambient pressure) on the MEC and results are in good agreement with those of a traditional PSR with detailed chemistry.