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Distribution by Scientific Domains

Chemistry	31%
Medical Sciences	17%
Engineering	14%
Information Science and Computing	9%
Life Sciences	7%
Psychology	4%
Mathematics and Statistics	4%
Humanities and Social Sciences	4%
2 Other Domains	10%

Selected Abstracts

SMILIB: Rapid Assembly of Combinatorial Libraries in SMILES Notation

MOLECULAR INFORMATICS, Issue 7 2003
Andreas Schüller
Abstract A software tool was developed for fast combinatorial library enumeration (SMILIB). Its particular features are its simplicity to use, high flexibility in constructing combinatorial libraries and high speed of library construction. SMILIB offers the possibility to construct very large combinatorial libraries using the flexible and portable SMILES format. Libraries are generated at rates of approximately 30,000 molecules per minute. Combinatorial building blocks are attached to scaffolds by means of linkers rather than to concatenate them directly. This allows for creation of easily customized libraries using linkers of different size and chemical nature. A web interface for a limited web-based version of the software is available at URL: www.modlab.de. An unlimited binary version of SMILIB for command line execution on Linux systems is available from this URL. [source]

Factors associated with discussion of care plans and code status at the time of hospital admission: Results from the Multicenter Hospitalist Study,

JOURNAL OF HOSPITAL MEDICINE, Issue 6 2008
Andrew D. Auerbach MD
Abstract BACKGROUND: Hospital admission is a time when patients are sickest and also often encountering an entirely new set of caregivers. As a result, understanding and documenting a patient's care preferences at hospital admission is critically important. OBJECTIVE: To understand factors associated with documentation of care planning discussions in patients admitted to general medical services at 6 academic medical centers. DESIGN: Observational cohort study using data collected during the Multicenter Hospitalist Study, conducted between July 1, 2002 and June 30, 2004. SETTING: Prospective trial enrolling patients admitted to general medicine services at 6 university-based teaching hospitals. PATIENTS: Patients were eligible for this study if they were 18 years of age or older, admitted to a hospitalist or nonhospitalist physician, and able to give informed consent. MEASUREMENTS: Presence of chart documentation that the admitting team had discussed care plans with the patient within the first 24 hours of hospitalization. Notations such as "full code" were not counted as a discussion, whereas notations such as "discussed care wishes and plan with patient" were counted. RESULTS: A total of 17,097 patients over the age of 18 gave informed consent and completed an interview and chart abstraction; of these, 1776 (10.3%) had a code status discussion (CD) documented in the first 24 hours of their admission. Patients with a CD were older (69 years vs. 56 years, P < 0.0001), more often white (52.8% vs. 43.3%, P < 0.0001), and more likely to have cancer (19.8% vs. 11.4%, P < 0.0001), or depression (35.1% vs. 30.9%, P < 0.0001). There was marked variability in CD documentation across sites of enrollment (2.8%-24.9%, P < 0.0001). Despite strong associations seen in unadjusted comparisons, in multivariable models many socioeconomic factors, functional status, comorbid illness, and documentation of a surrogate decision maker were only moderately associated with a CD (adjusted odds ratios all less than 2.0). However, patients' site of enrollment (odds ratios 1.74-5.14) and informal notations describing prehospital care wishes (eg, orders for "do not resuscitate"/"do not intubate;" odds ratios 3.22-11.32 compared with no preexisting documentation) were powerfully associated with CD documentation. Site remained a powerful influence even in patients with no documented prehospital wishes. LIMITATIONS: Our results are derived from a relatively small number of academic sites, and we cannot connect documentation differences to differences in patient outcomes. CONCLUSIONS: Documentation of a CD at admission was more strongly associated with informal documentation of prehospital care wishes and where the patient was hospitalized than legal care planning documents (such as durable power of attorney), or comorbid illnesses. Efforts to improve communication between hospitalists and their patients might target local documentation practices and culture. Journal of Hospital Medicine 2008;3(6):437,445. © 2008 Society of Hospital Medicine. [source]

Specification, planning, and execution of QoS-aware Grid workflows within the Amadeus environment

CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 4 2008
Ivona Brandic
Abstract Commonly, at a high level of abstraction Grid applications are specified based on the workflow paradigm. However, majority of Grid workflow systems either do not support Quality of Service (QoS), or provide only partial QoS support for certain phases of the workflow lifecycle. In this paper we present Amadeus, which is a holistic service-oriented environment for QoS-aware Grid workflows. Amadeus considers user requirements, in terms of QoS constraints, during workflow specification, planning, and execution. Within the Amadeus environment workflows and the associated QoS constraints are specified at a high level using an intuitive graphical notation. A distinguishing feature of our system is the support of a comprehensive set of QoS requirements, which considers in addition to performance and economical aspects also legal and security aspects. A set of QoS-aware service-oriented components is provided for workflow planning to support automatic constraint-based service negotiation and workflow optimization. For improving the efficiency of workflow planning we introduce a QoS-aware workflow reduction technique. Furthermore, we present our static and dynamic planning strategies for workflow execution in accordance with user-specified requirements. For each phase of the workflow lifecycle we experimentally evaluate the corresponding Amadeus components. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Young children's use of a visual aid: an experimental study of the effectiveness of training

DEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 6 2009
RALF FA COX PHD
We report an experiment concerning the use of a stand magnifier by young children with visual impairments (21 males, 12 females; mean age 4y 8mo [SD 11mo]). Children had a normative developmental level and a visual acuity of 0.4 or less (,20/50 in Snellen's notation). To measure magnifier use objectively, we developed a task that closely resembled the dynamics of its real-life (pre-reading) use. Children had to follow trails visually, from a start location to an unseen end location. This could only be done successfully and reliably by proper use of the magnifier. In addition to this, we analyzed the effect of specific training with the magnifier by using a repeated-measures (before and after training) matched-groups (with respect to age and near-visual acuity) design. Results established both the task's efficacy as an instrument for measuring magnifier use in young children and the effectiveness of the training. Improvement in task performance after training was found in both groups, except for the youngest children (<3y 6mo). On average, 1.8 times as many paths were followed in both groups after training (p=0.001). The without-magnifier training group became 2.5 times as good at finding the correct end location, whereas the with-magnifier training group became 4.3 times as good (p=0.05). [source]

Grinnellian and Eltonian niches and geographic distributions of species

ECOLOGY LETTERS, Issue 12 2007
Jorge Soberón
Abstract In the recent past, availability of large data sets of species presences has increased by orders of magnitude. This, together with developments in geographical information systems and statistical methods, has enabled scientists to calculate, for thousands of species, the environmental conditions of their distributional areas. The profiles thus obtained are obviously related to niche concepts in the Grinnell tradition, and separated from those in Elton's tradition. I argue that it is useful to define Grinnellian and Eltonian niches on the basis of the types of variables used to calculate them, the natural spatial scale at which they can be measured, and the dispersal of the individuals over the environment. I use set theory notation and analogies derived from population ecology theory to obtain formal definitions of areas of distribution and several types of niches. This brings clarity to several practical and fundamental questions in macroecology and biogeography. [source]

A thermodynamic approach to the instantaneous non-active power

EUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 6 2001
A. P. Morando, Article first published online: 22 MAR 200
Having schematically run through the transition from single-phase to three-phase relationships, the energy balance is formalised using Park vector notation. The imaginary power notation emerges. Leading back, in the sinusoidal case, to the usual reactive power, it generalises its specific contents in the case of variable states, explaining in particular a typical aspect of three-phase networks: the energy bouncing from one phase to another. This aspect can be seen as an index of power quality. At last, these same considerations are obtained by means of Lagrangian and thermodynamic approaches that lend a deeper meaning to the energy related quantities. [source]

PATHS IN TRANSNATIONAL TIME-SPACE: REPRESENTING MOBILITY BIOGRAPHIES OF YOUNG SWEDES

GEOGRAFISKA ANNALER SERIES B: HUMAN GEOGRAPHY, Issue 1 2008
Lotta Frändberg
ABSTRACT. This article sets out to capture and describe individual transnational mobility from a long-term, biographical perspective. The purpose is to discuss the use of a time-geographical form of notation to represent people's transnational mobility as paths in time and space, and to demonstrate how such representations can contribute to explaining some of the dynamics of longdistance mobility. An advantage of using time-space paths is that several aspects of an individual's travel biography can be represented in a single image: intensity and extensity are immediately evident, and the temporal and spatial relationships between the various mobility actions are made visible. Using data describing all transnational trips taken during childhood and adolescence by sixty-two Swedish youth with different backgrounds, three aspects of how trajectories develop over time are discussed in more detail. The first concerns overall change in travel pattern with time. A dominant pattern of increase in travel with increasing age is observed, indicating the importance of further investigating how travel behaviour is related to experience and life-course transitions. Second, sequential relationships between migration and temporary mobility are examined. In spite of the relatively small number of respondents, a wide range of such relationships are disclosed in the material. Third, regularity and repetition in long-distance travel patterns is discussed as an increasingly important aspect of contemporary transnational mobility. Among these young people, highly regular travel is often motivated by enduring long-distance social relationships, but is also generated by leisure or holiday travel alone. [source]

Comparison of waveform inversion, part 2: phase approach

GEOPHYSICAL PROSPECTING, Issue 4 2007
J. B. Bednar
ABSTRACT In this paper, we take advantage of the natural separation into amplitude and phase of a logarithmic-based approach to full-wavefield inversion and concentrate on deriving purely kinematic approaches for both conventional and logarithmic-based methods. We compare the resulting algorithms theoretically and empirically. To maintain consistency between this and the previous paper in this series, we continue with the same symbolism and notation and apply our new algorithms to the same three data sets. We show that both of these new techniques, although different in implementation style, share the same computational methodology. We also show that reverse-time back-propagation of the residuals for our new kinematic methods continues to be the basis for calculation of the steepest-descent vector. We conclude that the logarithmic phase-based method is more practical than its conventionally based counterpart, but, in spite of the fact that the conventional algorithm appears unstable, differences are not great. [source]

Tensor-based matrices in geometrically non-linear FEM

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 15 2005
V. V. Chekhov
Abstract In the framework of the object-oriented paradigm, advantages of using the index-free tensor notation in combination with the concept of generalized tensor-based matrix are considered as being the most corresponding to the paradigm. The advantages reveal itself in the disappearance of a semantic gap between various stages of creation of FEM applications (theoretical inferences, use of the numerical methods, object-oriented software implementation) and, as a result, use of the unified object model in all the stages, as well as simplification of theoretical transformations. Based on the considered approach, a new FEM equation for large strain analysis is developed and its solution technique is outlined. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Multi-objective turbomachinery optimization using a gradient-enhanced multi-layer perceptron

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 6 2009
M. C. Duta
Abstract Response surface models (RSMs) have found widespread use to reduce the overall computational cost of turbomachinery blading design optimization. Recent developments have seen the successful use of gradient information alongside sampled response values in building accurate response surfaces. This paper describes the use of gradients to enhance the performance of the RSM provided by a multi-layer perceptron. Gradient information is included in the perceptron by modifying the error function such that the perceptron is trained to fit the gradients as well as the response values. As a consequence, the back-propagation scheme that assists the training is also changed. The paper formulates the gradient-enhanced multi-layer perceptron using algebraic notation, with an emphasis on the ease of use and efficiency of computer code implementation. To illustrate the benefit of using gradient information, the enhanced neural network model is used in a multi-objective transonic fan blade optimization exercise of engineering relevance. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Aspect-enhanced goal-driven sequence diagram

INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 8 2010
Jonathan Lee
Recently, aspect-oriented approaches have resulted in a tremendous impact on the processing of broadly scoped properties during the development of software systems. However, the weaving mechanism of these crosscutting concerns cannot be easily represented with the extant unified modeling language (UML) notation at the early stage of software development life cycle. As an attempt toward the investigation of how the crosscutting behavior takes place, we proposed, in this work, an aspect-enhanced goal-driven approach to modeling the aspectual behavior in UML state transition diagrams and sequence diagrams with the proposed interaction operators based on the aspectual weaving semantics. By introducing the proposed interaction operations in the UML combined fragment, UML sequence diagrams can be further enhanced to support the modeling of the interactions between aspectual and base behavior in the analysis and design stage of software development. To further exemplify our points, the meeting scheduler system is chosen as a vehicle to illustrate the proposed approach. © 2010 Wiley Periodicals, Inc. [source]

An MDE modeling framework for measurable goal-oriented requirements

INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 8 2010
Fernando Molina
It is a proved fact that the appropriate management of requirements is one of the most influential factors in the success of software development projects. With the advent of the model-driven engineering (MDE) development paradigm, the need for formal gathering mechanisms, which provide the necessary degree of nonambiguity and detail, has led to the proposal of a myriad of requirements metamodels. However, a great disparity exists, both in the concepts/relationships and in the underlying semantics involved in each metamodel. Moreover, most existing proposals lack backward (e.g., alignment with business goals) or forward (e.g., connection with validation methods) traceability. In view of this situation, this article proposes a "measurable requirements metamodel" that offers support to the elicitation of measurable requirements. This support is based on the explicit connection of goals, requirements, and measures, thus fostering a goal-driven measurable requirements engineering (RE) perspective. Additionally, since it is well known that metamodels only reflect the abstract syntax of the modeling language, the proposed metamodel also includes a notation (concrete syntax) which, for reasons of understandability, is based on the goal-oriented requirements language (GRL) notation. This notation is supported by a unified modeling language (UML) profile that facilitates its adoption by RE analysts in the context of any UML-based software engineering process. To support this proposal, an Eclipse tool has been developed. This tool permits the integration of measurable requirements as a driving force in the context of a given MDE development process. © 2010 Wiley Periodicals, Inc. [source]

New computational algorithm for the prediction of protein folding types

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 1 2001
Nikola, tambuk
Abstract We present a new computational algorithm for the prediction of a secondary protein structure. The method enables the evaluation of ,- and ,-protein folding types from the nucleotide sequences. The procedure is based on the reflected Gray code algorithm of nucleotide,amino acid relationships, and represents the extension of Swanson's procedure in Ref. 4. It is shown that six-digit binary notation of each codon enables the prediction of ,- and ,-protein folds by means of the error-correcting linear block triple-check code. We tested the validity of the method on the test set of 140 proteins (70 ,- and 70 ,-folds). The test set consisted of standard ,- and ,-protein classes from Jpred and SCOP databases, with nucleotide sequence available in the GenBank database. 100% accurate classification of ,- and ,-protein folds, based on 39 dipeptide addresses derived by the error-correcting coding procedure was obtained by means of the logistic regression analysis (p<0.00000001). Classification tree and machine learning sequential minimal optimization (SMO) classifier confirmed the results by means 97.1% and 90% accurate classification, respectively. Protein fold prediction quality tested by means of leave-one-out cross-validation was a satisfactory 82.1% for the logistic regression and 81.4% for the SMO classifier. The presented procedure of computational analysis can be helpful in detecting the type of protein folding from the newly sequenced exon regions. The method enables quick, simple, and accurate prediction of ,- and ,-protein folds from the nucleotide sequence on a personal computer. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 84: 13,22, 2001 [source]

Resource management model and performance evaluation for satellite communications

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 2 2001
Axel Jahn
Abstract Efficient resource management is mandatory to achieve maximum system capacity for next generation communications systems. Resource management deals with the available spectral band, time, power, and space for a transmission signal. It includes (i) the frequency planning, (ii) the selection of transmit power, and (iii) the assignment of the channels and access nodes to the users. The paper presents a generalized notation as well as graph algorithms for resource management problems. Impairment graphs can be used for frequency planning, whereas flow graphs are suitable for channel access problems. To evaluate the performance of the resource management, service criteria (such as blocking or the carrier to interference ratio C/I) or efficiency criteria (bandwidth requirements) can be derived from the graphs. The resource management techniques are applied to satellite networks with non-geostationary orbits yielding time-variant network topologies. As a simple example, the channel assignment and capacity optimization of the EuroSky Way system are shown. Furthermore, a comparison of fixed, dynamic and hybrid channel allocation schemes (FCA, DCA, HCA) for a typical MEO satellite scenario is given. Satellite diversity and its impact on bandwidth requirement and transmission quality is also examined. Finally, it is shown how spread spectrum systems can be investigated with the presented tools. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Recognition of transposed melodies by absolute-pitch possessors

JAPANESE PSYCHOLOGICAL RESEARCH, Issue 4 2004
KEN'ICHI MIYAZAKI
Abstract:, Melody recognition experiments were carried out to investigate how absolute-pitch listeners deal with melodies in a tonal context. In each trial, a short standard melody was presented auditorily with piano sounds in Experiment 1 and visually in the format of musical notation in Experiment 2, and a comparison melody followed, always in piano sounds. Listeners were required to determine whether the two melodies were the same or different with respect to relative pitch. The listeners who had absolute pitch performed more poorly in comparing transposed melodies than in comparing nontransposed melodies, and their performance for transposed melodies was significantly poorer than that of the listeners who did not have absolute pitch. These results suggest that absolute pitch may work to a serious disadvantage to musicians in dealing with melodies in different tonal contexts. [source]

Mass selection bias in galaxy cluster peculiar velocities from the kinetic Sunyaev,Zel'dovich effect

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2006
Alan C. Peel
ABSTRACT Upcoming surveys for galaxy clusters using the Sunyaev,Zel'dovich effect are potentially sensitive enough to create a peculiar velocity catalogue. The statistics of these peculiar velocities are sensitive to cosmological parameters. We develop a method to explore parameter space using N -body simulations in order to quantify dark matter halo velocity statistics which will be useful for cluster peculiar velocity observations. We show that mass selection bias from a kinetic Sunyaev,Zel'dovich velocity catalogue forecasts rms peculiar velocities with a much more complicated ,m dependency than suggested by linear perturbation theory. In addition, we show that both two-point functions for velocities disagree with linear theory predictions out to ,40 h,1 Mpc separations. A pedagogical appendix is included developing linear theory notation with respect to the two-point peculiar velocities functions. [source]

Comments on tables of magnetic space groups

ACTA CRYSTALLOGRAPHICA SECTION A, Issue 2 2009
Hans Grimmer
Litvin [Acta Cryst. (2008), A64, 419,424 and supplementary material] extends much of the information contained in Volume A of International Tables for Crystallography for the 230 space-group types to the 1651 types of Shubnikov space groups, using Opechowski,Guccione (OG) notation for the space groups with a black,white lattice. It is pointed out that OG notation has crucial disadvantages compared to Belov,Neronova,Smirnova (BNS) notation. It is shown how Litvin's diagrams of symmetry elements for the orthorhombic Shubnikov space groups can be interpreted in terms of BNS symbols and how those containing e -glides can be simplified. A number of mistakes in the diagrams of Litvin are corrected. [source]

Elastic properties of two-dimensional quasicrystals

ACTA CRYSTALLOGRAPHICA SECTION A, Issue 4 2008
Hans Grimmer
Quasicrystals (QC) with two-dimensional quasiperiodic and one-dimensional periodic structure are considered. Their symmetry can be described by embedding the three-dimensional physical space VE in a five-dimensional superspace V, which is the direct sum of VE and a two-dimensional internal space VI. A displacement v in V can be written as v = u + w, where u,VE and w ,VI. If the QC has a point group P in VE that is crystallographic, it is assumed that w and a vector u,,VE lying in the plane in which the crystal is quasiperiodic transform under equivalent representations of P, inequivalent ones if the point group is 5-, 8-, 10- or 12-gonal. From the Neumann principle follow restrictions on the form of the phonon, phason and phonon,phason coupling contributions to the elastic stiffness matrix that can be determined by combining the restrictions obtained for a set of elements generating the point group of interest. For the phonon part, the restrictions obtained for the generating elements do not depend on the system to which the point group belongs. This remains true for the phason and coupling parts in the case of crystallographic point groups but, in general, breaks down for the non-crystallographic ones. The form of the symmetric 12 × 12 matrix giving the phonon, phason and phonon,phason coupling contributions to the elastic stiffness is presented in graphic notation. [source]

The mixing time of Glauber dynamics for coloring regular trees

RANDOM STRUCTURES AND ALGORITHMS, Issue 4 2010
Leslie Ann Goldberg
Abstract We consider Metropolis Glauber dynamics for sampling proper q -colorings of the n -vertex complete b -ary tree when 3 , q , b/(2lnb). We give both upper and lower bounds on the mixing time. Our upper bound is nO(b/ log b) and our lower bound is n,(b/(q log b)), where the constants implicit in the O() and ,() notation do not depend upon n, q or b. © 2010 Wiley Periodicals, Inc. Random Struct. Alg., 2010 [source]

Nomenclature of magnetic, incommensurate, composition-changed morphotropic, polytype, transient-structural and quasicrystalline phases undergoing phase transitions.

ACTA CRYSTALLOGRAPHICA SECTION A, Issue 5 2001

A general nomenclature applicable to the phases that form in any sequence of transitions in the solid state has been recommended by an IUCr Working Group [Acta Cryst. (1998). A54, 1028,1033]. The six-field notation of the first Report, hereafter I, was applied to the case of structural phase transitions, i.e. to transformations resulting from temperature and/or pressure changes between two crystalline (strictly periodic) phases involving modifications to the atomic arrangement. Extensive examples that illustrate the recommendations were provided. This second Report considers, within the framework of a similar six-field notation, the more complex nomenclature of transitions involving magnetic phases, incommensurate phases and transitions that occur as a function of composition change. Extension of the nomenclature to the case of phases with less clearly established relevance to standard schemes of transition in equilibrium systems, namely polytype phases, radiation-induced and other transient phases, quasicrystalline phases and their transitions is recommended more tentatively. A uniform notation for the translational periodicity, propagation vector or wavevector for magnetic and/or incommensurate substances is specified. The notation adopted for incommensurate phases, relying partly on the existence of an average structure, is also consistent with that for commensurate phases in a sequence. The sixth field of the nomenclature is used to emphasize the special features of polytypes and transient phases. As in I, illustrative examples are provided for each category of phase sequence. [source]

Structures of stable and metastable Ge2Bi2Te5, an intermetallic compound in a GeTe,Bi2Te3 pseudobinary system

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2007
Toshiyuki Matsunaga
Ge2Bi2Te5 in the GeTe,Bi2Te3 pseudobinary system has two single-crystalline phases: a metastable phase with an NaCl-type structure and a stable phase with a nine-layer trigonal structure. In the metastable phase, the structure consists, in the hexagonal notation, of infinitely alternating stacks of Te and Ge/Bi layers at equal intervals along the c axis. On the other hand, in the stable phase those two layers are stacked alternately nine times to form an NaCl block. The blocks are then piled to construct a nine-layered trigonal structure with cubic close-packed stacking. Both ends of each block are covered with Te layers, contrary to the infinite alternation of Ge/Bi and Te layers in the structure of the metastable phase. The Ge/Bi layers in the metastable phase contain as much as 20,at.,% vacancies; on the other hand, those in the stable phase are filled with atoms. These two crystalline phases in Ge2Bi2Te5 have identical atomic configurations to the two corresponding phases found in Ge2Sb2Te5. [source]

Automated assignment of graph-set descriptors for crystallographically symmetric molecules

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2000
W. D. Samuel Motherwell
Algorithms for the automatic assignment of graph-set notation for intermolecular networks have been extended to molecules having internal crystallographic symmetry, for patterns up to the second level. This provides a means of achieving systematic and consistent assignments for networks containing symmetric molecules. These methodologies have been implemented in the program RPLUTO. Examples are given of the application of the method to a number of molecules with hydrogen-bonded and other intermolecular networks, illustrating the diversity of the patterns that occur. [source]

Hydrogen-bond-directed supramolecular arrays in 4,4,-bipyridinium tetrachloroterephthalate dihydrate and bis(1,10-phenanthrolinium) tetrachloroterephthalate tetrachloroterephthalic acid trihydrate

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2009
Ming-Yang He
The title compounds, C10H10N22+·C8Cl4O42,·2H2O, (I), and 2C12H9N2+·C8Cl4O42,·C8H2Cl4O4·3H2O, (II), both crystallize as charge-transfer organic salts with the dianionic or neutral acid components lying on inversion centres. The acid and base subunits in (I) arrange alternately to generate a linear tape motif via N,H...O hydrogen bonds; these tapes are further combined into a three-dimensional architecture through multiple O,H...O and C,H...O interactions involving solvent water molecules. In contrast, the neutral and anionic acid components in (II) are linked to form a zigzag chain by means of O,H...O hydrogen bonds between acid groups, with dangling 1,10-phenanthrolinium units connected to these chains by carboxylate,pyridinium interactions with R22(7) hydrogen-bond notation. Adjacent chains are further extended to result in a two-dimensional corrugated layer network via,,, interactions. Inter-ion Cl...O interactions are also found in both (I) and (II). [source]

The Mathematical Contributions of Francesco Maurolico to the Theory of Music of the 16th Century (The Problems of a Manuscript)

CENTAURUS, Issue 3 2006
Tito M. Tonietti
Here, in part I, his main results are presented and also their differences compared with the classical tradition of the mathematical theory of music. These results are a new proof of the number of commas in the tone, the theory of ,ictus', and a new notation for the composition of proportions. This is followed, in part II, by an explanation of how the original corpus of these folios was put together. Finally, part III discusses the complex puzzle of the manuscripts (one still extant, another probably lost, ,) and of their possible connections with the 1575 edition of a part of the corpus. Possible scenarios of the story of the manuscripts and probable interventions of the Jesuits on this edition are described. [source]

4422: Snellen or logMAR in clinical ophthalmology

ACTA OPHTHALMOLOGICA, Issue 2010
W SPILEERS
Purpose The question remains if visual acuity measurements in clinical ophthalmology should use the well known Snellen notation or instead should switch to the slightly less intuitive logMAR notation Methods The differences in Snellen and logMAR notation will be explained in order to understand the (dis)advantages of each notation Results When measuring visual acuity, we should always take into account the purpose of the measurement: refraction and prescription of correction, reporting (low) visual acuity in clinical trials, ... Conclusion LogMAR notation of visual acuity has several advantages but the Snellen notation is widespread and can be maintained in specific conditions. [source]

On the Chemical Reaction of Matter with Antimatter

CHEMPHYSCHEM, Issue 8 2007
Evandro Lodi Rizzini Prof.
Abstract A chemical reaction between the building block antiatomic nucleus, the antiproton (p, or in chemical notation), and the hydrogen molecular ion () has been observed by the ATHENA collaboration at CERN. The charged pair interact via the long-range Coulomb force in the environment of a Penning trap which is purpose-built to observe antiproton interactions. The net result of the very low energy collision of the pair is the creation of an antiproton,proton bound state, known as protonium (Pn), together with the liberation of a hydrogen atom. The Pn is formed in a highly excited, metastable, state with a lifetime against annihilation of around 1 ,s. Effects are observed related to the temperature of the prior to the interaction, and this is discussed herein. [source]

Transfer of Mathematical Knowledge: The Portability of Generic Instantiations

CHILD DEVELOPMENT PERSPECTIVES, Issue 3 2009
Jennifer A. Kaminski
Abstract, Mathematical concepts are often difficult to acquire. This difficulty is evidenced by failure of knowledge to transfer to novel analogous situations. One approach to this challenge is to present the learner with a concrete instantiation of the to-be-learned concept. Concrete instantiations communicate more information than their abstract, generic counterparts and, in doing so, they may facilitate initial learning. However, this article argues that extraneous information in concrete instantiations may distract the learner from the relevant mathematical structure and, as a result, hinder transfer. At the same time, generic instantiations, such as traditional mathematical notation, can be learned by both children and adults and can, in turn, allow for transfer, suggesting that generic instantiations result in a portable knowledge representation. [source]

Evaluating the accuracy of Malformations Surveillance Program in detecting virilization due to congenital adrenal hyperplasia

CONGENITAL ANOMALIES, Issue 1 2005
Julie Travitz
ABSTRACT Malformations surveillance programs of newborn infants have been developed as a method for identifying serious and relatively common birth defects. The virilization of newborn infants with the classic 21-hydroxylase form of congenital adrenal hyperplasia must be identified early if the associated metabolic crisis in the perinatal period is to be prevented. We compared the detection of virilization associated with 21-hydroxylase congenital adrenal hyperplasia in infants by three methods: an ,active' malformations surveillance of medical records at a large urban hospital; routine medical care by examining physicians; and newborn biochemical screening of blood samples. The experience at a large maternity center in Boston, since 1972, showed that pediatricians often recognized affected females (6/6), but not males (0/2); the state newborn screening program, begun in 1990, identified correctly all affected males and females. The Active Malformations Surveillance Program was the least effective screening method, identifying four of six affected females and neither of the affected males. The low rate of detecting affected females by the Surveillance Program was attributed to a failure to sensitize the research assistants to the importance of physicians' notations regarding the signs and symptoms of virilization. The failure of examining physicians, and thereby, the malformations surveillance program, to detect virilized newborn males was due to the lack of consistent associated physical features. These comparisons between these three methods of detection can be used to design and improve malformations surveillance programs. [source]

Classical and advanced multilayered plate elements based upon PVD and RMVT.

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 3 2002
Part 2: Numerical implementations
Abstract This paper presents numerical evaluations related to the multilayered plate elements which were proposed in the companion paper (Part 1). Two-dimensional modellings with linear and higher-order (up to fourth order) expansion in the z -plate/layer thickness direction have been implemented for both displacements and transverse stresses. Layer-wise as well as equivalent single-layer modellings are considered on both frameworks of the principle of virtual displacements and Reissner mixed variational theorem. Such a variety has led to the implementation of 22 plate theories. As far as finite element approximation is concerned, three quadrilaters have been considered (four-, eight- and nine-noded plate elements). As a result, 22×3 different finite plate elements have been compared in the present analysis. The automatic procedure described in Part 1, which made extensive use of indicial notations, has herein been referred to in the considered computer implementations. An assessment has been made as far as convergence rates, numerical integrations and comparison to correspondent closed-form solutions are concerned. Extensive comparison to early and recently available results has been made for sample problems related to laminated and sandwich structures. Classical formulations, full mixed, hybrid, as well as three-dimensional solutions have been considered in such a comparison. Numerical substantiation of the importance of the fulfilment of zig-zag effects and interlaminar equilibria is given. The superiority of RMVT formulated finite elements over those related to PVD has been concluded. Two test cases are proposed as ,desk-beds' to establish the accuracy of the several theories. Results related to all the developed theories are presented for the first test case. The second test case, which is related to sandwich plates, restricts the comparison to the most significant implemented finite elements. It is proposed to refer to these test cases to establish the accuracy of existing or new higher-order, refined or improved finite elements for multilayered plate analyses. Copyright © 2002 John Wiley & Sons, Ltd. [source]