Performance Study of a Centralized Concurrency Control Algorithm for Distributed Database Systems using SIMULA

The stimulation technique has gained much importance in the performance studies of Concurrency Control (CC) algorithms for distributed database systems. However, details regarding the simulation methodology and implementation are seldom mentioned in the literature. One objective of this paper is to elaborate the simulation methodology using SIMULA. Detailed studies have been carried out on a centralised CC algorithm and its modified version. The results compare well with a previously reported study on these algorithms. Here, additional results concerning the update intensiveness of transactions and the degree of conflict are obtained. The degree of conflict is quantitatively measured and it is seen to be a useful performance index. Regression analysis has been carried out on the results, and an optimisation study using the regression model has been performed to minimise the response time. Such a study may prove useful for the design of distributed database systems.

Equatorial modes observed in atmospheric variables

Wavenumber-frequency spectral analysis of different atmospheric variables has been carried Out using 25 years of data. The area considered is the tropical belt 25 degrees S-25 degrees N. A combined FFT wavelet analysis method has been used for this purpose. Variables considered are outgoing long wave radiation (OLR), 850 hPa divergence, zonal and meridional winds at 850, 500 and 200 hPa levels, sea level pressure and 850 hPa geopotential height. It is shown that the spectra of different variables have some common properties, but each variable also has few features diffe:rent from the rest. While Kelvin mode is prominent in OLR, and zonal winds, it is not clearly observed in pressure and geopotential height fields; the latter two have a dominant wavenumber zero mode not seen in other variables except in meridional wind at 200 hPa and 850 hPa divergences. Different dominant modes in the tropics show significant variations on sub-seasonal time scales.

Occurrence, divergence and evolution of intrinsic terminators across Eubacteria

In Escherichia coli, the canonical intrinsic terminator of transcription includes a palindrome followed by a U-trail on the transcript. The apparent underrepresentation of such terminators in eubacterial genomes led us to develop a rapid and accurate algorithm, GeSTer, to predict putative intrinsic terminators. Now, we have analyzed 378 genome sequences with an improved version of GeSTer. Our results indicate that the canonical E. coli type terminators are not overwhelmingly abundant in eubacteria. The atypical structures, having stem-loop structures but lacking ‘U’ trail, occur downstream of genes in all the analyzed genomes but different phyla show conserved preference for different types of terminators. This propensity correlates with genomic GC content and presence of the factor, Rho. 60–70% of identified terminators in all the genomes show “optimized” stem-length and ΔG. These results provide evidence that eubacteria extensively rely on the mechanism of intrinsic termination, with a considerable divergence in their structure, positioning and prevalence. The software and detailed results for individual genomes are freely available on request

Sulphate ion dynamics in a-alums studied by esr at high pressures

The variation of zero-field splitting and linewidth of Cr3+ ion in KCr and KAI alums with hydrostatic pressure and with temperature is investigated. A model for the apparent phase transition is proposed on the basis of the reorientational motion of the SO2-4 groups.

Use of Multiblade Coordinates for Helicopter Flap-Lag Stability with Dynamic Inflow

Rotor flap-lag stability in forward flight is studied with and without dynamic inflow feedback via a multiblade coordinate transformation (MCT). The algebra of MCT is found to be so involved that it requires checking the final equations by independent means. Accordingly, an assessment of three derivation methods is given. Numerical results are presented for three- and four-bladed rotors up to an advance ratio of 0.5. While the constant-coefficient approximation under trimmed conditions is satisfactory for low-frequency modes, it is not satisfactory for high-frequency modes or for untrimmed conditions. The advantages of multiblade coordinates are pronounced when the blades are coupled by dynamic inflow.

Determination of the optically equivalent model in three-dimensional photoelasticity

Any stressed photoelastic medium can be reduced to an optically equivalent model consisting of a linear retarder, with retardation 1 and principal axis at azimuth 1, and a pure rotator of power 2. The paper describes two simple methods to determine these quantities experimentally. Further, a method is described to overcome the problem of rotational effects in scattered-light investigations. This new method makes use of the experimentally determined characteristic parameters

Construction of a cDNA clone for a nuclear-coded subunit of cytochrome c oxidase from rat liver

A cDNA library for 6S–9S poly(A)-containing RNA from rat liver was constructed in Image . Initial screening of the clones was carried out using single stranded 32P-labeled cDNA prepared against poly(A)-containing RNA isolated from immunoadsorbed polyribosomes enriched for the nuclear-coded subunit messenger RNAs of cytochrome c oxidase. One of the clones, pCO89, was found to hybridize with the messenger RNA for subunit VIC. The DNA sequence of the insert in pCO89 was carried out and it has got extensive homology with the C-terminal 33 amino acids of subunit VIC from beef heart cytochrome c oxidase. In addition, the insert contained 146 bp, corresponding to a portion of the 3′-non-coding region. Northern blot analysis of rat liver RNA with the nick-translated insert of pCO89 revealed that the messenger RNA for subunit VI would contain around 510 bases.

Determination of the optically equivalent model in three-dimensional photoelasticity

Any stressed photoelastic medium can be reduced to an optically equivalent model consisting of a linear retarder, with retardation delta1 and principal axis at azimuth phgr1, and a pure rotator of power phgr2. The paper describes two simple methods to determine these quantities experimentally. Further, a method is described to overcome the problem of rotational effects in scattered-light investigations. This new method makes use of the experimentally determined characteristic parameters.

The Crystal and Molecular Structure of l-(Diphenylmethyl)azetidin-3-ol

1-(Diphenylmethyl)azetidin-3-ol is triclinic, space group P1, with a=8.479(2), b=17.294(4),c = 10.606 (3) A, a = 118.59 (2),/~ = 100.30 (2), y = 89.63 (2) °, Z = 4. The structure was solved by multisolution methods and refined to an R of 0.044 for 2755 reflexions. The four-membered rings in the two independent molecules are puckered with dihedral angles of 156 and 153 ° . The two molecules differ in conformation with respect to rotation of the phenyl rings about the C-C bonds. The structure is stabilized by a network of O-H. • • N intermolecular hydrogen bonds.

Further characterization of the saccharide specificity of peanut (Arachis hypogaea) agglutinin

2-Dansylamino-2-deoxy-D-galactose (GalNDns) has been shown to bind to peanut (Arachis hypogaea) agglutinin (PNA) in a saccharide-specific manner. This binding was accompanied by a five-fold increase in the fluorescence of GalNDns. The interaction was characterized by an association constant of 0.15 mM at 15° and ΔH and ΔS values of -57.04 kJ·mol-1 and -118.1 J·mol-1.K-1, respectively. Binding of a variety of other mono-, di- and oligo-saccharides to PNA, studied by monitoring their ability to dissociate the PNA-GalNDns complex, revealed that PNA interacts with several T-antigen-related structures, such as β-d-Galp-(1→3)-D-GalNAc, β-D-Galp-(1→3)-α-D-GalpNAcOMe, and β-D-Galp-(1→3)-α-D-GalpNAc(1→3)-Ser, as well as the asialo-G(M1) tetrasaccharide, with comparable affinity, thus showing that this lectin does not discriminate between saccharides in which the penultimate sugar of the β-D-Galp-(1→3)-D-GalNAc unit is the α or β anomer, in contrast to jacalin (Artocarpus integrifolia agglutinin), another anti T-lectin which preferentially binds to β-D-Galp-(1→3)-α-D-GalNAc and does not recognize β-D-Galp-(1→3)-β-D-GalNAc or the related asialo-G(M1) oligosaccharide. These studies also indicated that, in the extended combining region of PNA which accommodates a disaccharide, the primary subsite (subsite A) is highly specific for D-galactose, whereas the secondary subsite (subsite B) is less specific and can accommodate various structures, such as D-galactose, 2-acetamido-2-deoxy-D-galactose, D-glucose, and 2-acetamido-2-deoxy-D-glucose.

Subspace intersection method of high-resolution bearing estimation in shallow ocean using acoustic vector sensors

The subspace intersection method (SIM) provides unbiased bearing estimates of multiple acoustic sources in a range-independent shallow ocean using a one-dimensional search without prior knowledge of source ranges and depths. The original formulation of this method is based on deployment of a horizontal linear array of hydrophones which measure acoustic pressure. In this paper, we extend SIM to an array of acoustic vector sensors which measure pressure as well as all components of particle velocity. Use of vector sensors reduces the minimum number of sensors required by a factor of 4, and also eliminates the constraint that the intersensor spacing should not exceed half wavelength. The additional information provided by the vector sensors leads to performance enhancement in the form of lower estimation error and higher resolution.

Aging response and its effect on the functional properties of Cu–Al–Ni shape memory alloys

The β-phase aging response of Cu–Al–Ni single crystal shape memory alloys (SMAs) within the temperature range of 473–573 K has been investigated. Alloys in austenitic (Cu–14.1Al–4Ni wt.%, alloy A) and martensitic (Cu–13.4Al–4Ni wt.%, alloy M) conditions at room temperature were considered. Aged samples show presence of β1′ and γ1′ martensites in both the alloys and formation of γ2 precipitates in the alloy A. The differential scanning calorimetry (DSC) thermograms of the aged samples show increase in transformation temperatures as well as transformation hysteresis with aging. Dynamic mechanical analysis (DMA) was conducted on both the alloys to ascertain the role of precipitates and martensitic transition on tan δ, which characterizes the damping behaviour of the material. With aging, a steady decrease in tan δ value was observed in both the alloys, which was attributed to the decrease in the number of interfaces per unit area with increasing aging temperature. Moreover, in alloy A, as the volume fraction of precipitate increases with aging, the movement of martensitic interfaces is restricted causing a decreased tan δ.

The generalized anomeric effect in the 1,3-thiazolidines: Evidence forboth sulphur and nitrogen as electron donors. Crystal structures of various N-acylthiazolidines including mercury(II) complexes. Possible relevance to penicillin action

Evidence for the generalized anomeric effect (GAE) in the N-acyl-1,3-thiazolidines, an important structural motif in the penicillins, was sought in the crystal structures of N-(4-nitrobenzoyl)-1,3-thiazolidine and its (2:1) complex with mercuric chloride, N-acetyl-2-phenyl-1,3-thiazolidine, and the (2:1) complex of N-benzoyl-1,3-thiazolidine with mercuric bromide. An inverse relationship was generally observed between the. C-2-N and C-2-S bond lengths of the thiazolidine ring, supporting the existence of the GAE. (Maximal bond length changes were similar to 0.04 angstrom for C-2-N-3, S-1-C-2, and similar to 0.08 angstrom for N-3-C-6.) Comparison with N-acylpyrrolidines and tetrahydrothiophenes indicates that both the nitrogen-to-sulphur and sulphur-to-nitrogen GAE's operate simultaneously in the 1,3-thiazolidines, the former being dominant. (This is analogous to the normal and exo-anomeric effects in pyranoses, and also leads to an interesting application of Baldwin's rules.) The nitrogen-to-sulphur GAE is generally enhanced in the mercury(II) complexes (presumably via coordination at the sulphur); a 'competition' between the GAE and the amide resonance of the N-acyl moiety is apparent. There is evidence for a 'push-pull' charge transfer between the thiazolidine moieties in the mercury(II) complexes, and for a 'back-donation' of charge from the bromine atoms to the thiazolidine moieties in the HgBr2 complex. (The sulphur atom appears to be sp(2) hybridised in the mercury(II) complexes, possibly for stereoelectronic reasons.) These results are apparently relevant to the mode of action of the penicillins. (c) 2006 Elsevier B.V. All rights reserved.

Preliminary X-ray crystallographic analysis of 2-methylcitrate synthase from Salmonella typhimurium

Analysis of the genomic sequences of Escherichia coli and Salmonella typhimurium has revealed the presence of several homologues of the well studied citrate synthase (CS). One of these homologues has been shown to code for 2-methylcitrate synthase (2-MCS) activity. 2-MCS catalyzes one of the steps in the 2-methylcitric acid cycle found in these organisms for the degradation of propionate to pyruvate and succinate. In the present work, the gene coding for 2-MCS from S. typhimurium (StPrpC) was cloned in pRSET-C vector and overexpressed in E. coli. The protein was purified to homogeneity using Ni-NTA affinity chromatography. The purified protein was crystallized using the microbatch-under-oil method. The StPrpC crystals diffracted X-rays to 2.4 A resolution and belonged to the triclinic space group P1, with unit-cell parameters a = 92.068, b = 118.159, c = 120.659 A, alpha = 60.84, beta = 67.77, gamma = 81.92 degrees. Computation of rotation functions using the X-ray diffraction data shows that the protein is likely to be a decamer of identical subunits, unlike CSs, which are dimers or hexamers.

Chain structures in alkali metal borophosphates: synthesis and characterization of K3[BP3O9(OH)3] and Rb3[B2P3O11(OH)2]

Two new alkali metal borophosphates, K-3[BP(3)o(9)(OH)(3)] and Rb-3[B2P3O11(OH)(2)], were synthesized by applying solvothermal techniques using ethanol as solvent. The crystal structures were solved by means of single-crystal X-ray diffraction (K-3[BP3O9(OH)(3)], monoclinic, C2/c (No. 15), a = 2454.6(8) pm, b = 736.3(2) pm, c = 1406.2(4) pm, beta = 118.35(2)degrees, Z = 8; Rb-3[B2P3O11(OH)(2)], monoclinic, P2(1)/c (No. 14), a = 781.6(2) pm, b:= 667.3(2) pm, c = 2424.8(5) pm, beta = 92.88(1)degrees, Z = 4). Both crystal structures comprise borophosphate chain anions. While for the rubidium compound a loop-branched chain motif is found as common for most of the chain anions in alkali metal borophosphates, the crystal structure of the potassium phase comprises the first open-branched chain with the highest phosphate content found so far in this group of compounds. Both chain anions are Closely related to known anhydrous or hydrated phases, and the structural relations are discussed in terms of how the presence of OH groups and hydrogen bonds as well as number, charge, and size of charge balancing cations influence the 3D structural arrangement. The anionic entities are classified in terms of general principles of structural systematics for borophosphates.