bluuebunny/crossref_metadata_2025 huggingface dataset:
4-Acylamino-4H-1,2,4-triazoles and related structures: new investigations of their chemical and physicochemical properties associated with their particular exocyclic amide function
Authors: Pirotte Bernard , Tullio Pascal De , Masereel Bernard , Schynts Marc , Delarge Jacques , Dupont Léon , Thunus Léopold
Published: May 2006

The acido-basic behavior of 4-acylamino-4H-1,2,4-triazoles and of the related structures, 4-acylamino-4H-1,2,4-triazolium salts, 4-acylamino-1,2,4-triazoline-3-thiones, and 4-acylamino-1,2,4-triazolin-3-ones, has been compared. Among the triazolium salts examined, the 1-carboxymethyl-4-phenylacetylamino derivative has been selected as a particular triazolium salt bearing two acidic centres, a carboxylic acid group and an exocyclic amide group. This compound has been isolated in three different ionic forms corresponding to different protonation and deprotonation states of the molecule. For these compounds, IR, NMR, and X-ray data were compared and the preferential localization site of the labile proton on the betainic intermediate structure has been discussed. Taking into account that deprotonation of the amide function of 4-acylamino-4H-1,2,4-triazolium salts may introduce a negative pole in the proximity of the strong electrophilic carbon atom in the 2-position of the ring, reactivity of different triazolium salts toward the nucleophilic addition of the hydride ion has been compared. In particular, 4-acylamino-4H-1,2,4-triazolium salts free of alkyl substituent on the amide nitrogen failed to give the corresponding 4-acylamino-Δ2-1,2,4-triazolines after reaction with the hydride ion, while, under the same conditions, the 4-N-methyl derivatives were transformed into this unusual ring system in good yields. In this case, no decrease of reactivity toward the nucleophilic agent was observed since, as a result of the N-al-kylation, no deprotonation of the amide group can occur in these alkaline experimental conditions.
Molecular recognition XIV. Monte Carlo simulation of the hydration of the combining site of a Lectin
Authors: Beierbeck H. , Delbaere L. T. J. , Vandonselaar M. , Lemieux R. U.
Published: May 2006

Monte Carlo simulations of the hydration of the combining sites of the divalent lectin IV of Griffonia simplicifolia were carried out using the X-ray structure of the native lectin at 2.15 Å resolution. The regions of the combining sites are identical shallow polyamphiphilic cavities with a surface area of approximately 240 Å2 and an average depth of only about 2.2 Å. To reduce the CPU time requirements for Monte Carlo simulations of the hydration of the combining site of the native lectin, a fragment of the protein structure was examined that contained only 62 of the 243 amino acid residues and was present in both of the two subunits of the protein. This portion of the lectin, which encompassed the combining site and its immediate surroundings, was examined, employing 250 water molecules to near symmetrically cover an area of about 370 Å2 over and about the combining site with a density of 1 at 300 K. As was previously found in similar studies of the hydration of the Lewis b tetrasaccharide, the nonpolar regions are much less densely hydrated than the adjacent polar regions. This situation is considered to arise because of the hydrogen-bonding requirement for water molecules to bridge over nonpolar regions of varying dimensions. It is expected, therefore, that the association of complementary hydrophilic surfaces in aqueous solution must involve, in addition to the establishment of the usual intermolecular forces of attraction, a collapse of water structure over "flickering cavities" for return to bulk. This collapse can be expected to contribute to the driving force for association both through a decrease in enthalpy (higher density) and through an increase in entropy (greater disorder). This property of hydrated polyamphiphilic surfaces may contribute importantly to the driving force of all associations in aqueous solution since virtually all organic molecules are polyamphiphilic in character.
Effect of multiple encounters on vibrational to translational energy transfer
Authors: Snider Neil
Published: May 2006

Vibrational to translational energy transfer was studied computationally and analytically for collinear, impulsive collisions with square well oscillators, harmonic oscillators, and Morse oscillators. At a fixed temperature T the average number of encounters is between one and two if the vibrational energy EV is large compared to kT and (or) if the relative mass of the collider is small. If these conditions are met, [Formula: see text] the average energy transferred per collision, varies nearly linearly with EV over a wide range. If the average number of encounters is greater than two, [Formula: see text] as a function of EV has a more complicated form. The average final energy, [Formula: see text] is less than what is predicted by the single encounter impulsive collision (SEI) model. Other things being equal, the ratio of the actual average final energy to the SEI average final energy is roughly the same for all of the above mentioned oscillators.
Valence shell absolute photoabsorption oscillator strengths, constrained dipole oscillator strength distributions, and dipole properties for CH3NH2, (CH3)2NH, and (CH3)3N
Authors: Burton Gordon R. , Chan Wing Fat , Cooper Glyn , Brion C.E. , Kumar Ashok , Meath William J.
Published: May 2006

Dipole (e,e) spectroscopy has been used to measure the absolute photoabsorption oscillator strengths (cross sections) for the valence shells of CH3NH2, (CH3)2NH, and (CH3)3N from the photoabsorption threshold to 250 eV at low resolution (∼1 eV fwhm) and to 31 eV at high resolution (0.048 eV fwhm). The observed peaks in the photoabsorption spectra of the methylamines have been assigned to transitions to Rydberg orbital upper states. Our measured photoabsorption data, augmented by mixture rule estimates for high photon energies, have been used in conjunction with Thomas–Reiche–Kuhn sum rule and molar refractivity constraints, to construct constrained dipole oscillator strength distributions for each of the methylamines. From these constrained dipole oscillator strength distributions a wide range of related dipole properties have been calculated for each of the methylamines, and in most cases the results so obtained represent the first (reliable) determination of these properties.
Bond energies for cationic bare metal hydrides of the first transition series: a challenge to density functional theory
Authors: Ziegler Tom , Li Jian
Published: May 2006

Density functional methods based on the Local Density Approximation (LDA) and its nonlocal extensions (LDA/NL) are used to calculate the bond energies, as well as the bond lengths and vibrational frequencies of the high spin, open shell first-row transition metal hydride cations MH+. The D298(M+—H) LDA/NL bond energies are in good agreement with experiment for the early transition metals with errors within 5 kcal/mol. However, the error increases to 6–l3 kcal/mol for the late metal hydrides. An analysis based on atomic properties such as 4s ionization potentials and 4s to 3d promotion energies revealed that the large error in bonding energies among the late transition metals can be attributed to an overestimation of the exchange energy in the DFT schemes. It is shown that a simple remedy, based on a thermodynamic cycle, can improve the agreement between experimental and theoretical bond energies. However, simple cationic bare metal complexes such as MH+ remains a challenge to approximate DFT.
Ab initio molecular orbital calculations on the neutral hydrolysis and methanolysis of azetidinones, including catalysis by water. Relationship to the mechanism of action of β-lactam antibiotics
Authors: Wolfe Saul , Kim Chan-Kyung , Yang Kiyull
Published: May 2006

The docking of penicillins to a computer model of the active site of the penicillin-binding protein of Streptomyces R61 produces structures that exhibit a four-centred interaction between the O-H of a serine residue and the (O)C-N of the β-lactam ring. If such a structure is a stationary point on the reaction coordinate for the acylation of the serine OH by the β-lactam carbonyl group, the acylation mechanism would appear to consist of O—C and H—N bond formation, concerted with the cleavage of the C—N bond. The existence of this "N-protonation" mechanism, and the energetics of this mechanism in comparison to the usual "O-protonation" pathway in which proton transfer to oxygen and addition to the carbonyl group precede C—N bond fission, have been examined by ab initio MO calculations on the neutral hydrolysis and methanolysis of N-methylazetidinone, penam, and penam-3α-carboxylate. The geometries of reactants and transition structures have been optimized fully at the 3-21G or 3-21G* levels, the existence of transition structures has been confirmed by vibrational analysis, thermochemical data have been computed, and the one-point energies of all structures have been determined at the MP2/6-31G* level. The N-protonation mechanism is found to exist with all substrates, and to be preferred over the O-protonation mechanism by over 5 kcal/mol. The activation energies are 5 kcal/mol lower in the bicyclic penam than in the monocyclic N-methylazetidinone, and attack from the convex face is preferred over attack from the concave face. The introduction of a 3α-carboxylate group, as in penicillin itself, results in an additional 5 kcal/mol decrease in activation energy. The origins of these trends are discussed. Since the active sites of some penicillin-recognizing enzymes contain at least one water molecule, catalysis of the foregoing reactions by one water molecule has also been examined. The catalysis amounts to over 10 kcal/mol in both the N- and O-protonation mechanisms, and the preference for the N-protonation mechanism is maintained. It is concluded that penicillin complexes to its receptor in such a manner as to allow acylation of the active site serine residue to proceed via the energetically most favourable mechanism.
Thiobenzoates of lead (II) and bismuth (III). The crystal and molecular structures of (AsPh4) [Pb(SOCPh)3] and Pb(SOCPh)2(S2CP{c-C6H11}3)
Authors: Burnett Thomas R. , Dean Philip A.W. , Vittal Jagadese J.
Published: May 2006

The compounds M(SOCPh)n (M = Pb, n = 2; M = Bi, n = 3) have been prepared by the reaction of M(OAc)n or M(SPh)n with a slight excess of PhCOSH in MeOH. The ligands PhCOS−, (c-C6H11)3PCS2 and (c-C6H11)3PO solubilize Pb(SOCPh)2 in solvents in which it is otherwise poorly soluble. Neither Ph3P nor Ph3P increase the solubility of Pb(SOCPh)2 and none of the above five ligands enhance the solubility of very poorly soluble Bi(SOCPh)3. Solubilization of the Pb(II) compound is due in each case to a 1:1 reaction as shown by the isolation of (Ph4As)(SOCPh)3] (1) and Pb(SOCPh)2(S2CP{c-C6H11}3) (2), and by a multi-NMR (31P, 207Pb) study of the system Pb(SOCPh): (c-C6H11)3PO (in which unidentified more ligand-rich species are also formed). 1 and 2 have been characterized by multi-nuclear magnetic resonance spectroscopy (13C, 31P, 207Pb, as appropriate) and by single crystal X-ray diffractometry techniques at −50 °C. The compound 1•CH2Cl2(=1′) crystallizes in the triclinic space group [Formula: see text] with Z = 2. The crystal data for 1′ are a = 13.395(4), (b) = 16.585(3), c = 11.582(3) Å, α = 88.03(2), β = 112.34(2), γ = 113.00(2)°, V = 2171(1) Å3, ρcalcd(ρobsd) = 1.663 (1.65(3)) g cm−3, RF = 0.038, Rw = 0.035. In the [Pb(SOCPh)3]− anion the Pb—S distances are in the range 2.703(3)–2.763(2) Å. The primary coordination geometry around Pb is trigonal pyramidal (PbS3 kernel). There are four additional weaker interactions with oxygen atoms, one from each ligand and one a bridging interaction that links the anions in a centrosymmetric dimer. The Pb—O distances are in the range 2.879(6)− 3.298(7) Å. Compound 2 crystallizes in the monoclinic space group, P21/c with Z = 4. The crystal data for 2 are, a = 17.039(2), b = 11.834(2), c = 18.965(3) Å, β = 116.44(1)°, V = 3424(1) Å3 ρcalcd ρ(obsd) = 1.621 (1.61(3)) g cm−3RF = 0.034, Rw = 0.029. The (c-C6H11)3PCS2 ligand binds in an anisobidentate manner and the primary coordination geometry around Pb in the neutral molecule is trigonal pyramidal, the primary Pb—S distances in the PbS3 kernel being 2.626(2), 2.755(2), and 2.885(2) Å. The weakly bound sulfur of the (c-C6H11)3PCS2 acts as a bridge, again producing a centrosymmetric dimer. In addition to the two weak interactions to sulfur (3.350(2), 3.639(2) Å) there are also two involving the oxygens of the PhCOS− ligands (2.626(5), 3.002(5) Å).2 is the first complex containing a ligand of the type R3PCS2 bound to a Main Group element.
Contribution à l'étude du polymorphisme de quelques métallothionéines par chromatographie liquide de haute performance
Authors: Bordin Guy , Raposo Fernando Cordeiro , Rodriguez Adela-Rosa
Published: May 2006

Four commercially available metallothioneins from rabbit liver (RL, RL I, RL II) and from horse kidney (HK) have been studied by size exclusion chromatography and by reverse-phase chromatography, to characterize their polymorphism. The isoforms are detected by UV at 250 nm. Separations by size exclusion show that the metallothioneins are partially dimerized, with molar rates of dimer ranging from 5% for HK to 15% for RL II. The four chromatograms obtained by reverse phase exhibit a different morphology: RL separates in four main isoforms, RL I into two, RL II into three, and HK into two. An attribution of the various peaks for the RL, RL I, and RL II series is proposed. The comparable results obtained by the two methods allow us to estimate that RL is composed of 20–30% RL I and 70–80% of RL II.
Photoionophores derived from crown ether polycarboxylic acids: synthesis, ion binding, and spectroscopic characterization
Authors: Fyles Thomas M. , Suresh Valia Veettil
Published: May 2006

Three types of potential photoionophores based on polycarboxylic acid crown ethers were prepared, and their cation complexation behaviours and spectroscopic properties were surveyed. The first type were neutral macropolycyclic hosts prepared by capping across the faces of the crown ether with aromatic diamine chromophores. The second were bis-crown ether carboxylates bearing a bridging aromatic chromophore. The third type appended an additional chromophore-donor site on the crown ether carboxylic acid framework. Cation complexation was examined by potentiometric titration. The neutral ligands were rather poor hosts for alkali metal cations. The other two types of crown ether carboxylates showed a combination of size selectivity and electrostatic stabilization, leading to significant and selective ion binding in water. Ligands of the third type also exhibited cation-dependent absorption spectra in neutral and basic aqueous solution. No significant alkali metal or alkaline earth cation-induced perturbation of the emission spectra was uncovered, but a sodium- and cesium-dependent long wavelength emission enhancement was observed in one of the neutral ligand systems.
Solubility and solvation of pyronato and pyridinato complexes of aluminum, gallium, and indium in alcohol–water mixtures
Authors: Beatty Emma , Burgess John , Patel Marttand S.
Published: May 2006

Solubilities are reported for aluminum, gallium, and indium tris-ligand complexes of the pyrones maltol and ethylmaltol and of a number of 4-pyridinones in water–methanol and water–tert-butyl alcohol solvent mixtures, at 298.2 K. Trends and patterns in transfer chemical potentials derived from these solubilities are discussed in terms of the dependence of solvation on the nature of the ligand, the metal, and the cosolvent.
The oscillatory Belousov–Zhabotinsky reaction with flavones in batch systems using aqueous–DMF mixed medium
Authors: Maya G. , Lalitha P.V. , Ramaswamy R.
Published: May 2006

Oscillatory systems of the Belousov–Zhabotinsky type with flavones as substrates are described for the first time. Since quercetin and morin are water insoluble, a mixed medium containing DMF and water was used with one of the three catalysts Ce(III), ferroin, or Mn(II). The oscillatory behaviour of a water-soluble substrate (gallic acid) was studied in nine different aqueous–organic mixed media as well as in pure aqueous medium in the bromate–Ce(III) system. The results obtained from a catalyzed system with quercetin or morin as the substrate in an aqueous–organic mixed medium are in agreement with the accepted (FKN) mechanism for an aqueous system.
Facilitating student learning through study abroad and international projects
Authors: Fuller Ursula , Amillo June , Laxer Cary , McCracken W. Michael , Mertz Joseph
Published: May 2006

Computer science is inherently international but its effective application depends on an understanding of the local culture in which it is being used. Students and faculty need to be prepared to operate in this global environment. This ITiCSE working group report discusses why an international dimension is an important component of a computer science, student's education. It describes ways to add an international dimension to student learning and provides several case studies as examples. Barriers to international study are identified, and recommendations for how to do more to expand the international opportunities of computer science students are discussed.
The equivalence of sequential and associate information structure models
Authors: McGowan Clement , Wegner Peter
Published: May 2006

Interpreters for programming languages may be defined in terms of the information structures (data structures) generated during program execution. This paper develops a class of proof techniques for proving equivalence between two classes of programming language interpreters referred to as associative interpreters and sequential interpreters. The relation between associative and sequential interpreters is briefly illustrated first for arithmetic expression evaluation and then for lambda calculus evaluation, and the strategy for proving equivalence is briefly described. The proof technique is worked out in detail both for arithmetic expression evaluation and for lambda calculus evaluation. The relatively trivial case of arithmetic expression evaluation is considered in detail in order to illustrate the basic structure of the proof in a context familiar to the uninitiated. The proof of equivalence of associative and sequential lambda calculus interpreters demonstrates a nontrivial equivalence proof and at the same time provides valuable insights into the relation between mathematical definitions of the lambda calculus and practical implementations of the lambda calculus. It is shown that an understanding of lambda calculus interpretation in turn provides insights into interpretation mechanisms for block structure languages like ALGOL 60.
Generalized data structures in Madcap VI
Authors: Morris James B. , Wells Mark B.
Published: May 2006

The data structures proposed for the Madcap VI programming language are described. The declaration, value specification, and referencing of these structures are defined formally and their implementation using "codewords" is discussed. A structure declaration has the form of a directed tree, and a structure itself, since it can contain references to other structures, including itself, has the form of a directed graph. Levels of the tree may be ordered or unordered. Variables of primitive data-type (real, complex, etc.) are naturally considered as empty structures. The possibility for both multi-and fractional-word representation of structures is evident, but, of course the language itself is implementation independent. Thus a field is equivalent to a sub-structure. The Madcap VI generalized data structures are compared to data structure concepts in PL/1.
Hidden line elimination and topographic representation
Authors: Spital Glenn
Published: May 2006

The purpose of this paper is to present a Hidden Line Algorithm, the chief advantage of which is speed. It is predicated on a particular space-structuring format. Instead of a polyhedral representation, I use a topographical representation wherein a set of contour lines defines the three-dimensional conformation of an object or surface. Both the type of format and the speed of execution recommend this algorithm to applications which involve irregular, complex, convoluted, and finely detailed shapes.
Design automation for microfluidics-based biochips
Authors: Chakrabarty Krishnendu , Zeng Jun
Published: May 2006

Advances in microfluidics technology offer exciting possibilities in the realm of enzymatic analysis, DNA analysis, proteomic analysis involving proteins and peptides, immunoassays, implantable drug delivery devices, and environmental toxicity monitoring. Microfluidics-based biochips are therefore gaining popularity for clinical diagnostics and other laboratory procedures involving molecular biology. As more bioassays are executed concurrently on a biochip, system integration and design complexity are expected to increase dramatically. This paper presents different actuation mechanisms for microfluidics-based biochips, as well as associated design automation trends and challenges. The underlying physical principles of eletrokinetics, electrohydrodynamics, and thermo-capillarity are discussed. Next, the paper presents an overview of an integrated system-level design methodology that attempts to address key issues in the modeling, simulation, synthesis, testing and reconfiguration of digital microfluidics-based biochips. The top-down design automation will facilitate the integration of fluidic components with microelectronic component in next-generation system-on-chip designs.
Constraint satisfaction techniques for diagnosing errors in design by contract software
Authors: Ceballos Rafael , Gasca Rafael Martinez , Borrego Diana
Published: May 2006

Design by Contract enables the development of more reliable and robust software applications. In this paper, a methodology that diagnoses errors in software is proposed. This is based on the combination of Design by Contract, Model-based Diagnosis and Constraint Programming. Contracts are specified by using assertions. These assertions together with an abstraction of the source code are transformed into constraints. The methodology detects if the contracts are consistent, and if there are incompatibilities between contracts and source code. The process is automatic and is based on constraint programming.
Software product lines structuring based upon market demands
Authors: Ereño Montse , Landa Uxue , Cortazar Dra. Rebeca
Published: May 2006

Nowadays the increasing demand for customized products and services in traditional areas such as Automotion Manufacturing or Aeronautical Component Engineering is being satisfied with a new approach called "Product Platform". This successful approach is also being considered in the design of software-based components in these areas, which are recognized as complex and critical.In this paper, we present the research that is being carried out at Mondragon University. This effort focuses on the analysis of existing Product Platform Development methods and the transference of this know-how to Software Product Development.As a result, a Software Product Line (SPL) development method will be defined and applied in a real case. This method will be based upon market demands, so it should be flexible enough to respond to customer's requests and market pressure. In this paper we will explain in detail one step of the process. This step is concerned with how QFD technique can be used to the specification of components in a SPL.
Culture and environment as determinants of women's participation in computing
Authors: Frieze Carol , Hazzan Orit , Blum Lenore , Dias M. Bernardine
Published: May 2006

There are some arguments that suggest women need academic handholding, such as a "female friendly" curriculum, in order for them to participate and be successful in computer science and related fields. Then there are other arguments that suggest we need to change the field to suit women or help women adjust to the field. In this paper we present a different perspective that shows none of these may be necessary. The "Women-CS Fit" is already there! Specifically, under certain cultural and environmental conditions we can see that women fit very well into computing fields and what we have been attributing to gender is actually the result of cultural and environmental conditions. The reasons for women participating in -- or not participating in -- the field of computer science have little to do with gender and a lot to do with culture. In other words, we need to recognize that this is a cultural issue, and an issue that concerns us all. Appropriate local interventions in the micro-culture can have large effect. This argument is illustrated in this paper by three case studies.
The back end of a grading system
Authors: Noonan Robert E.
Published: May 2006

The phases of a grading system are discussed, namely: delivery, assessment, marking, review, and return. A system which addresses the back end, namely, the last three phases, is described. Late binding of marks to a graded project is used, simplifying the revision process. The use of the system by various courses and its benefits are discussed.
A robust web programming and graphics course for non-majors
Authors: Gousie Michael B.
Published: May 2006

Web Programming, Graphics, and Design is a course with no prerequisites that teaches non-computer science majors how to create their own sophisticated web pages. The course begins with the use of popular software such as Dreamweaver and Fireworks and then progresses to writing interactive web pages in Java. Students learn how to program with Java's Abstract Window Toolkit (AWT) as well as the graphics library, leading to the creation of 3D images. Solving problems involving mathematics is a theme throughout much of the course. Finally, following Wheaton College's curricular emphasis on inter-departmental offerings, the course is linked with Graphic Design I in the Art Department, enabling students to learn the design portion in even greater depth.
Chirp on crickets
Authors: Xu Li , Martin Fred G.
Published: May 2006

Traditionally, the topics of compiler construction and language processing have been taught as an elective course in Computer Science curricula. As such, students may graduate with little understanding or experience with the useful techniques embodied in modern compiler construction.In this paper, we present the design of
Chirp
, a language specification and compiler implementation. As a language,
Chirp
is based on Java/C syntax conventions and is matched with the stack-based virtual machine that is built into the simple yet versatile Handy Cricket educational robot controller. As a compiler, the
Chirp
design is a series of Java components. These modules demonstrate key compiler construction techniques including lexing, parsing, intermediate representation, semantic analysis, error handling and code generation.We have designed a 6-week teaching module to be integrated into an intermediate-level undergraduate programming class. In the module, students will incrementally build the
Chirp
compiler, culminating with code generation for the Cricket controller. They will test their work on both physical Cricket-based robots and a web-based Cricket simulator. The
Chirp
system and our pedagogical design provides a realistic and engaging environment to teach compilers in undergraduate core programming courses.
Evaluations of target tracking in wireless sensor networks
Authors: Tran Sam Phu Manh , Yang T. Andrew
Published: May 2006

Target tracking is one of the most important applications of wireless sensor networks. Optimized computation and energy dissipation are critical requirements to maximize the lifetime of the sensor network. There exists a demand for self-organizing and routing capabilities in the sensor network. Existing methods attempting to achieve these requirements, such as the LEACH-based algorithms, however, suffer either redundancy in data and sensor node deployment, or complex computation incurred in the sensor nodes. Those drawbacks result in energy use inefficiency and/or complex computation overhead.
OCO
, or
Optimized Communication and Organization
, is an algorithm that ensures maximum accuracy of target tracking, efficient energy dissipation, and low computation overhead on the sensor nodes. Simulation evaluations of OCO are compared with other two methods under various scenarios.
CyberTech I
Authors: Woszczynski Amy B.
Published: May 2006

As high schools begin to offer more distance learning courses, universities have an opportunity to establish partnerships to deliver online computer science courses. As we face declining enrollment, these partnerships offer the ability to reach a significant portion of students who may not otherwise consider computer science. Particularly for underrepresented groups, such as African-Americans, Hispanics, women, and first-generation college students, these partnerships offer the potential to recruit additional students into computing fields. This paper describes the first portion of a multi-year partnership between a large university and multiple high schools in a metropolitan area. CyberTech I is an online introduction to computer science course offered to high school students by university faculty. Initial results indicate that students were generally satisfied with their online course experience and plan to continue to participate in the program. We describe the curriculum introduced and discuss some of the challenges faced and the lessons learned.
XP practices applied to grading
Authors: Levine David B. , Walker Henry M.
Published: May 2006

The grading of student work is of the utmost importance to a computer science educator. This paper examines the practices of eXtreme Programming (XP) and considers how they apply to the tasks of assigning grades to student work, even as those grades must both evaluate the student objectively and communicate with her personally.
Designing an adaptive learning module to teach software testing
Authors: Agarwal Rahul , Edwards Stephen H. , Pérez-Quiñones Manuel A.
Published: May 2006

Adaptive learning systems aim to precisely tailor education and training to the individual needs of learners. Such systems use an internal model of a user's current knowledge to adjust the navigational affordances and presentation order of material. The user model is incrementally built and updated as the user demonstrates mastery by completing exercises and tests. Designing courses that are delivered adaptively involves addressing many complexities. This paper describes experiences designing the first adaptive module in a series intended to teach software testing skills. Experiences in using the first module and a preliminary evaluation of its effectiveness are presented.
Accessibility first!
Authors: Rosmaita Brian J.
Published: May 2006

This paper proposes an
accessibility first
pedogogy for web design, in which the course is organized around the requirement of implementing web pages accessible to visually impaired computer users. This approach and its advantages are discussed in detail.
Realism and simplicity
Authors: DeRosa Peter , Shen Kai , Stewart Christopher , Pearson Jonathan
Published: May 2006

Operating system laboratory assignments based on bare hardware or detailed machine simulators can be excessively challenging for many students. In the most often used approach, students develop kernels on virtual machines with a much simplified hardware interface. Traditionally this simplification goes so far as to make realistic performance measurement impossible. We propose
Vesper
, an instructional disk drive simulator with a high degree of performance realism. Vesper retains simplicity while providing timing statistics close to that of real disk drives. The key to our approach is to provide hardware abstractions that are simple but yet capable of capturing device interactions with major performance impacts. Vesper laboratory assignments allow students to realistically explore the performance consequences of various system designs without the cumbersome aspects of the real hardware interface. This paper describes the design and implementation of the Vesper disk drive simulator. We evaluate the effectiveness of Vesper-based laboratory assignments in terms of operating system performance evaluation. Student experience and feedback are also reported.
An innovative approach to teaching refactoring
Authors: Smith Suzanne , Stoecklin Sara , Serino Catharina
Published: May 2006

Refactoring is the process of transforming the internal structure of existing code while keeping the integrity of the code's functional requirements. Refactoring is proven to increase program maintainability, flexibility, and understandability and is recognized as a best practice in the software development community. However, with the exception of courses or lectures on extreme programming, refactoring is overlooked in the computer science curriculum. This paper helps demystify refactoring by introducing an incremental approach for teaching refactoring on the college level. Through this hands-on approach, refactoring can become an integral component in the computer science curriculum and an innovative means of reinforcing software engineering principles and good development practices. The approach and three introductory lessons are presented in this paper.
Motivating OOP by blowing things up
Authors: Bierre Kevin , Ventura Phil , Phelps Andrew , Egert Christopher
Published: May 2006

For the introductory student, the process of learning to program is an arduous task. Not only does the student have to learn the syntax of a programming language, he or she also has to apply concepts of object-oriented design and software construction in service of the projects created within the classroom. Unfortunately, as students further their study of programming, they often feel disconnected from the examples and projects they construct as part of their coursework. Projects are often perceived as toy problems and do not match the graphics-rich, interactive notion of programming that students bring with them to class. In addition, projects and classroom exercises do not convey the appropriate level of complexity and fail in the task of challenging the student to critically think about what they are constructing. This paper discusses TankBrains, a cooperative and competitive programming project presented to students in the latter part of their introductory programming course sequence. Students are challenged to create simple tank artificial intelligences as teams, which are later tested against each other in head-to-head combat. Students create their TankBrains within a collaborative virtual environment, which enforces the physics and rules of the combat simulation. Students must also present their strategies and findings to each other. This paper also examines how the use of the TankBrain system influences the students' perception regarding achievements and learning in the classroom.
Can graduating students design software systems?
Authors: Eckerdal Anna , McCartney Robert , Moström Jan Erik , Ratcliffe Mark , Zander Carol
Published: May 2006

This paper examines software designs produced by students nearing completion of their Computer Science degrees. The results of this multi-national, multi institutional experiment present some interesting implications for educators.
Social networks generate interest in computer science
Authors: Alt Casey , Astrachan Owen , Forbes Jeffrey , Lucic Richard , Rodger Susan
Published: May 2006

For forty years programming has been the foundation of introductory computer science. Despite exponential increases in computational power during this period, examples used in introductory courses have remained largely unchanged. The incredible growth in statistics courses at all levels, in contrast with the decline of students taking computer science courses, points to the potential for introducing computer science at many levels without emphasizing the process of programming: leverage the expertise and role-models provided by high school mathematics teachers by studying
topics that arise from social networks and modeling to introduce computer science as an alternative to the traditional programming approach
. This new approach may capture the interest of a broad population of students, crossing gender boundaries. We are developing modules that we hope will capture student interest and provide a compelling yet intellectually rich area of study. We plan to incorporate these modules into existing courses in math, statistics, and computer science at a wide variety of schools at all levels.
The inverted curriculum in practice
Authors: Pedroni Michela , Meyer Bertrand
Published: May 2006

Teaching introductory programming today presents considerable challenges, which traditional techniques do not properly address. Students start with a wide variety of backgrounds and prior computing experience; to retain their attention it is useful to provide graphical interfaces at the level set by video games; and with the ever-increasing presence of computing in society the stakes are higher, requiring a computing curriculum to introduce students early to the issues of large systems. We address these challenges through an "outside-in" approach, or "inverted curriculum", which emphasizes the reuse of existing components in an example domain involving graphics and multimedia, a gentle introduction to formal reasoning thanks to Design by Contract techniques, and an object-oriented method throughout. The new course has now been taught twice, with considerable gathering of student data and feedback; we report on this experience and its continuation.
Poker as a group project for artificial intelligence
Authors: Scheessele Michael R. , Schriefer Thomas
Published: May 2006

Assigning the development of a poker-playing agent as a group project allows flexibility with respect to the topics and techniques typically covered in an introductory Artificial Intelligence course. A poker agent project also provides students the experience of 'authentic' AI research, due to the status of poker as an 'unsolved' problem in AI. Despite this status, a poker agent project is feasible for a semester, half-semester, or quarter-long group project. Problems in assigning group projects are also considered, as are suggestions for mitigating these problems.
TiVo-lution
Authors: Barton Jim
Published: May 2006

One of the greatest challenges of designing a computer system is in making sure the system itself is "invisible" to the user. The system should simply be a conduit to the desired result. There are many examples of such purpose-built systems, ranging from modern automobiles to mobile phones.
Mapping live sequence chart to coloured petri nets for analysis and verification of embedded systems
Authors: Amorim Leonardo , Maciel Paulo , Nogueira Meuse , Barreto Raimundo , Tavares Eduardo
Published: May 2006

This paper presents a methodology for mapping the Live Sequence Chart (LSC) language to an equivalent Coloured Petri Net (CPN) model as an approach for analysis and verification of embedded systems' properties. LSC is a language for system specification, allowing one to specify what should happen for all execution of the system as well as the modeling of anti-scenarios. However, analysis and verification of systems' properties are not possible. In order to allow diagnosis of inconsistent specifications, besides simulation, verification and analysis should be considered. Therefore the proposition of a CPN model for LSC allows verification and analysis of systems described in LSC, hence, contributing for increasing designers' confidence on the system development process and reducing risks that may lead to project failure.
Software estimation
Authors: Bajaj Nonika , Tyagi Alok , Agarwal Rakesh
Published: May 2006

Software projects are failing because of the poor project planning and due to this estimation have gained interest in recent times. Estimation process reduces the risk around schedule and cost. Effective software project estimation is one of the most challenging activities in software development that software industries are facing. Proper project planning and control is not possible without a reliable estimate.
Top down
and
bottom up
are traditionally the most commonly used techniques to estimate the effort of the software project. Studies suggest that the software companies should use Bottom up approach unless they have a vast experience from the similar projects. The goal of this research work is to extend the existing bottom up approach to achieve greater precision in the estimates. This work proposes the use and concepts of fuzzy set theory to extend the Bottom up approach to Fuzzy bottom up approach. With the productivity rate generated by fuzzy bottom up, derived values such as effort of development can be more precisely determined.
A Convenient One-pot Synthesis of Unsymmetrical Selenium Compounds Using Bis(trimethylsilyl) Selenide
Authors: Segi Masahito , Kato Masakazu , Nakajima Tadashi , Suga Sohei , Sonoda Noboru
Published: May 2006

The reaction of bis(trimethylsilyl) selenide with n-BuLi followed by alkylation with an R1X gave alkyl silyl selenides. The repetition of a similar one-pot operation with the second n-BuLi and R2X yielded unsymmetrical selenides (R1SeR2) in good yields. This one-pot procedure could be also applicable to the syntheses of selenolesters, selenolcarbonates, and a phosphinothioyl selenide.
Near-infrared Absorbing Polymethine Dyes Terminally Substituted by 1-Benzothiopyrylium Ring
Authors: Nakazumi Hiroyuki , Watanabe Shigeru , Kado Seiji , Kitao Teijiro
Published: May 2006

Unsymmetrical polymethine near-infrared dyes terminally containing 1-benzothiopyrylium ring and N,N-dimethylamino group were first prepared from 2-methyl-, 4-methyl-, and 2,4-dimethyl-1-benzothiopyrylium salts. It is found that the maximum wavelength of these dyes on PMMA is remarkably shifted to a shorter wavelength (60–200 nm) compared with that in solution.
Naturally Occurring Rubiadins. A Caveat
Authors: Boisvert Louise , Brassard Paul
Published: May 2006

A number of typical rubiadins have been prepared by unambiguous means, and their characteristics reveal that the structures of most natural products so designated are erroneous.
Electrochemical Synthesis of Polypyrrole Films Containing Metal Oxide Particles
Authors: Yoneyama Hiroshi , Shoji Yoshihiro , Kawai Katsuhiro
Published: May 2006

Electrochemical oxidation of pyrrole has been undertaken in aqueous suspensions of metal oxides in the presence and absence of hydroxides. It has been found that polypyrrole films containing oxide particles can be prepared for oxides having the isoelectric point smaller than pH ca. 4.5 provided that pH of the oxide suspensions is high enough to build up negative charges on the oxide surfaces.
Boron Trifluoride-Assisted Alkylation of 2-Isoxazolines. A Novel Route to N-Unsubstituted Isoxazolidines
Authors: Uno Hidemitsu , Terakawa Tetsuya , Suzuki Hitomi
Published: May 2006

In the presence of boron trifluoride, 2-isoxazolines undergo the addition of organolithiums to afford N-unsubstituted isoxazolidines in moderate to good yields.
Synthesis of the Eudesmanolide with Proposed Structure for Septuplinolide
Authors: Tada Masahiro , Kanamori Akira
Published: May 2006

An eudesmanolide which has a proposed structure for septuplinolide was synthesized stereo-selectively. The spectral data of synthesized eudesmanolide are not identical with the reported data of septuplinolide to show that the proposed structure of septulpinolide is incorrect.
Facile Synthesis of Trifluoromethyl Ketones by Palladium-Catalyzed Carroll Type Reaction
Authors: Shimizu Isao , Ishii Hirotoshi , Tasaka Atsuma
Published: May 2006

Distannoxane-catalyzed transesterification of ethyl 4,4,4-trifluoroacetoacetate with allylic alcohols gave the corresponding allylic esters, which were subjected to palladium-catalyzed decarboxylation-allylation to give trifluoromethyl ketones.
Epoxidation of α,β-Unsaturated Ketones Using Dialkylzinc-Oxygen Reagents
Authors: Yamamoto Keiji , Yamamoto Norio
Published: May 2006

The autoxidation of the dialkylzinc well precedes the conjugate addition of this reagent to α,β-unsaturated ketones, which undergo nucleophilic epoxidation with the resulting alkylperoxozinc species.
pH-Dependent Molecular Recognition Performed by a Polycationic Cubic Azaparacyclophane
Authors: Murakami Yukito , Kikuchi Jun-ichi , Ohno Teruhisa , Hirayama Takayuki , Nishimura Hiroshi
Published: May 2006

A cubic cyclophane surrounded by six faces, each being constructed with the [3.3.3.3]azaparacyclophane ring, behaved as a polycationic host in acidic aqueous media and exhibited pH-dependent binding behavior toward an anionic guest, ANS, since microenvironmental properties of the host cavity are varied by the extent of protonation at the nitrogen atoms.
A New System of Autoreduction of Hemin with Isocyanide
Authors: Nakano Taku , Kitamura Yoshitaka
Published: May 2006

A new autoreduction system of hemin was established in the case of synthetic hemins with hydroquinone and isocyanide. The reduction of hemin needed both of hydroquinone and isocyanide. Kinetic studies suggested that a six-coordinated and low-spin iron porphyrin complex was an intermediate of the reduction.
Stereoselectivities in the Coupling Reactions between 2-Deoxyribose Derivative and Silylated Adenine
Authors: Kawakami Hiroshi , Matsushita Hajime , Shibagaki Makoto , Naoi Yoshitake , Itoh Kazuo , Yoshikoshi Hajime
Published: May 2006

Stereoselectivities in the coupling reactions between 1-α-chloro-2-deoxyribose derivative and silylated adenine have been examined under various conditions. The best result was obtained when the coupling reaction was carried out in 1,2,4-trichlorobenzene in the presence of triethylamine.
Dynamic Structure of Paramagnetic Complexes, MeCpMo(CO)3(p-benzoquinone) (MeCp = η5-CH3C5H4), Formed by Photochemical Reaction of [MeCpMo(CO)3]2 with p-Benzoquinones as Studied by EPR Spectroscopy
Authors: Hanaya Minoru , Iwaizumi Masamoto
Published: May 2006

The existence of the intramolecular motion and the most stable structure of the paramagnetic complexes, MeCpMo(CO)3(p-benzoquinone), formed by photochemical reaction of [MeCpMo(CO)3]2 with p-benzoquinones were revealed by the EPR spectroscopic study.
Catalysis by Interlayer Anions of a Synthetic Hydrotalcite-like Mineral in a Halide Exchange between Organic Halides
Authors: Suzuki Eiichi , Okamoto Masaki , Ono Yoshio
Published: May 2006

Exchgangeable Cl− anions in the interlayer sites of a hydrotalcite-like mineral, Mg6Al2(OH)16Cl2·4H2O, catalyzed a halide-exchange reaction between C6H5CH2Cl and C4H9Br or C4H9I in toluene or in DMF. Thus, for example, a reaction between C6H5CH2Cl (33 mmol) and C4H9Br (195 mmol) in DMF at 343 K for 20 h gave C6H5CH2Br with a 90% yield on a C6H5CH2Cl basis.
Asymmetrically Distorted Structure of (Polypyridyl)ruthenium(II) Complex with Sterically Hindered Ligand
Authors: Ichida Hikaru , Tachiyashiki Satoshi , Sasaki Yukiyoshi
Published: May 2006

In [Ru(phen)2(dmphen)]2+(dmphen = 2,9-dimethyl-1,10-phenanthroline), the potential strong steric interaction between methyl groups and phen ligands was relieved not by the elongation of Ru–N(dmphen) bonds but by an asymmetrical distortion of coordination geometry. The phen ligands were compressed and the dmphen was elongated from the D3 symmetry. The plane of dmphen tilted 15 from the N–Ru–N coordination plane.
Synthesis and the Absolute Configuration of Panaxacol
Authors: Fujimoto Yasuo , Satoh Mitsuru , Takeuchi Naoki , Kirisawa Makoto
Published: May 2006

Panaxacol, a polyacetylene isolated from the callus of Panax ginseng, was synthesized from D-(−)-diethyl tartrate. The absolute configuration of panaxacol was determined to be 9R, 10R.
Palladium-Catalyzed Carbonyl Allylation of Diketo Compounds by Allylic Alcohols with SnCl2
Authors: Masuyama Yoshiro , Tsunoda Tomoyoshi , Kurusu Yasuhiko
Published: May 2006

Palladium-catalyzed diallylation of 1,2-diketones and 1,2-ketoaldehyde by allyl alcohol with SnCl2 in DMI was accelerated and proceeded diastereoselectively thanks to a chelation of a carbonyl group to Sn(IV) (tin alkoxide) in the corresponding monoallylated intermediates.