Compact Labeling Scheme for XML Ancestor Queries

XML documents are often viewed as trees (basically the parse tree of the document), and queries over such documents typically test for ancestor relationships among tree nodes. Search engines process such queries using an index structure summarizing the ancestor relations. In the index, each document item (tree node) is identified using some logical id (node label), such that, given two labels, the engine can determine the ancestor relationship between the corresponding nodes. The length of the labels is a main factor of the index size. Therefore, reducing this length, even by a constant factor, is a critical issue. In this work we consider the following problem. Given a rooted XML tree T, label the nodes of T in the most compact way such that given the labels of two nodes, one can determine in constant time, by looking at the labels only, whether one node is an ancestor of the other. Labelings currently being used are all variants of the following interval scheme. Number the leaves say from left to right and label each node with a pair consisting of the numbers of its smallest and largest leaf descendants. An ancestor query then amounts to an interval containment test on the labels. The maximum label length using this scheme is 2 log n, where n is the number of nodes in the tree. (All logarithms in this paper are to base 2.) The focus of this work is finding a scheme that works best in practice on real XML data. We suggest an orthogonal prefix-based approach, where the labeling is such that an ancestor query roughly amounts to testing whether one label is a prefix of the other. We present several new labeling schemes based on this approach and analyze their performance both theoretically and empirically.     

Vortex Matter in the Presence of Magnetic Pinning Centra

Within the non-linear Ginzburg-Landau (GL) theory, we investigate the vortex structure of a thin type II superconductor with a ferromagnetic dot on top of it. Spontaneous creation of vortex-antivortex pairs as well as specific arrangements of vortices are found. We show that the equilibrium vortex phase diagram depends on the size of the magnetic dot and its magnetization, and we discuss the shell structure of the multivortex states with magic numbers which are size and magnetization dependent.     

Calculation of the thermal response of buildings by the total thermal time constant method

This paper describes the theoretical development and experimental proof of the total thermal time constant (TTTC) method for calculation of the thermal response of buildings. The output is obtained in the form of time sequences of temperature, under given time-variation of internal heating load, or in the form of time dependent heating (or cooling) loads, under given patterns of internal temperature variation in time.TTTC method considers ventilation conditions, internal heating, metabolic heat production, cooling, solar radiation absorption on, and longwave i.r. radiation loss from, the external surfaces, solar radiation penetration through windows and the external air temperature and humidity variations in time. The main feature of this method is that each component of the building is represented here, as a heat transfer path, only by two easy to calculate numbers: the thermal resistance and the TTTC (this includes thermal resistances and heat capacities and their relative position in the heat transfer path, including partitions and ceilings) [1–3]. The two parameters characterize the influence of the element on the thermal response of a building as a whole.Experimental demonstration of the accuracy of the TTTC method in computing the thermal response of buildings is presented and compared with measured temperature time patterns both in models and actual buildings under various external conditions. The method is useful not only for the thermal design of buildings and the selection of building materials, but also for the design of passive methods of climatization, e.g. by the use of solar radiation for heating, and conversely, the cooling of a structure by longwave radiation loss (to the outer space through the atmosphere) and by ventilation. Thermal storage and insulation properties are also considered.     

The functional status of the parathyroid in adult spasmophilia patients estimated by plasma parathormone assay

In 25 cases of spasmophilia the parathyroid function was assessed by complete exploration of the P-Ca metabolism and radioimmunoassay (RIA) of parathormone (PTH). Concomitantly the bone mineralization status was assessed by induced hypercalciuria tests and administration of 30 mg vitamin D2. RIA of PTH revealed increased values in 50% of the cases. The values fall within the range of secondary hyperparathyroidism, but this percentage varies with the values of the parathyroid function obtained by P-Ca metabolism explorations. The increased PTH values do no correlate with the level of plasma total calcium, ionic calcium, and magnesemia. Nor do they correlate with the bone mineralization disorders or the duration of the disease and the age of the patients.     

About a property of a class of linear time-varying systems derived from the controllability and observability matrices

This correspondence deals with an application of a theorem of Silverman and Meadows which specifies conditions forntime-variablen-dimensional vectors to be linearly dependent. From this theorem conditions are derived which allow one to verify whether a linear time-varying system admits a realization in which either the state matrixAand the state-input matrixB, or the state matrixAand the state-output matrixC, are constant.     

Interfacial properties of hydrocarbons

The interfacial tension of aliphatic hydrocarbon-water systems has been found to increase in a linear fashion as a function of the log of hydrocarbon chain length. Contrary to the literature, values of ϕ and γ H ₂ ^d O were observed to be also dependent on hydrocarbon chain length. The relationship between hydrocarbon chain length and interfacial tension is actually opposite to that predicted by Antonow’s rule. The results are discussed in terms of hydrocarbon-water interaction and water-structure at the interface.     

Cobalt-based alloys for orthopaedic applications studied by electrochemical and XPS analysis

The composition of the passive layers formed by electrochemical oxidation at different passivation potentials on Co-Cr-Mo and Co-Ni-Cr-Mo alloys in simulated physiological solution (SPS), with and without the complexing agent EDTA, was studied by X-ray photoelectron spectroscopy. Composition as a function of depth, cationic fraction and thickness of the passive film was determined. Chromium oxide is shown to be the major constituent of the passive layer on both Co-Cr-Mo and Co-Ni-Cr-Mo alloys. The minor constituents of the passive layers, Co- and Mo-oxide in the case of Co-Cr-Mo alloy and Ni-, Co- and Mo-oxides in the case of Co-Ni-Cr-Mo alloy, are also located in the outer part of the layer. EDTA affects the formation of the passive layer on each alloy. The content of Co-, Ni- and Mo-oxide in the passive layer is lower in the presence of EDTA, thus indicating increased solubility associated with higher stability constants for complexes of metal cations with EDTA.     

A spectroscopic and electrochemical investigation of the oxidation pathway of glycyl-d,l-methionine and its N-acetyl derivative induced by gold(III)

The ¹H nuclear magnetic resonance spectroscopy was applied to study the reaction of the dipeptide glycyl-d,l-methionine (H-Gly-d,l-Met-OH) and its N-acetylated derivative (Ac-Gly-d,l-Met-OH) with hydrogen tetrachloridoaurate(III) (H[AuCl₄]). The corresponding peptide and [AuCl₄]^– were reacted in 1:1, 2:1, and 3:1 molar ratios, and all reactions were performed at pD 2.45 in 0.01 M DCl as solvent and at 25°C. It was found that the first step of these reactions is coordination of Au(III) to the thioether sulfur atom with formation of the gold(III)-peptide complex [AuCl₃(R-Gly-Met-OH-S)] (R=H or Ac). This intermediate gold(III) complex further reacts with an additional methionine residue to generate the R-Gly-Met-OH chlorosulfonium cation as the second intermediate product, which readily undergoes hydrolysis to give the corresponding sulfoxide. The oxidation of the methionine residue in the reaction between H-Gly-d,l-Met-OH and [AuCl₄]^– was five times faster (k ₂ = 0.363 ± 0.074 M^-1s^-1) in comparison to the same process with N-acetylated derivative of this peptide (k ₂ = 0.074 ± 0.007 M^-1s^-1). The difference in the oxidation rates between these two peptides can be attributed to the free terminal amino group of H-Gly-d,l-Met-OH dipeptide. The mechanism of this redox process is discussed and, for its clarification, the reaction of the H-Gly-d,l-Met-OH dipeptide with [AuCl₄]^– was additionally investigated by UV-Vis and cyclic voltammetry techniques. From these measurements, it was shown that the [AuCl₂]^– complex under these experimental conditions has a strong tendency to disproportionate, forming [AuCl₄]^– and metallic gold. This study contributes to a better understanding of the mechanism of the Au(III)-induced oxidation of methionine and methionine-containing peptides in relation to the severe toxicity of anti-arthritic and anticancer gold-based drugs.     

Cultivating creative thinking in engineering student teams: Can a computer-mediated virtual laboratory help?

In engineering design, engineers must be able to think creatively, effectively toggling between divergent thinking (developing multiple novel ideas) and convergent thinking (pursuing an appropriate idea using engineering analyses). However, creative thinking is not emphasized in many undergraduate engineering programs. In this empirical study, we analyze the divergent thinking of teams working on a virtual laboratory project. Fifteen student teams' solution paths–as represented by Model Maps–were analyzed to characterize and compare the various elements of divergent thinking: fluency, flexibility, and originality. The solution paths of these teams were compared in two physical laboratory projects and to experts completing the same virtual laboratory project. We found that students demonstrated more divergent thinking in the virtual laboratory project than in the physical laboratory projects; yet, divergent thinking and quality of solution did not correlate. There was little difference between measured elements of divergent thinking between student teams and experts.