New parametrization method for dissipative particle dynamics

We introduce an improved method of parameterizing the Groot-Warren version of Dissipative Particle Dynamics (DPD) by exploiting a correspondence between DPD and Scatchard-Hildebrand regular solution theory. The new parameterization scheme widens the realm of applicability of DPD by first removing the restriction of equal repulsive interactions between like beads, and second, by relating all conservative interactions between beads directly to cohesive energy densities. We establish the correspondence by deriving an expression for the Helmoltz free energy of mixing obtaining a heat of mixing which is exactly the same form as that for a regular mixture (quadratic in the volume fraction) and an entropy of mixing which reduces to the ideal entropy of mixing for equal molar volumes. We equate the conservative interaction parameters in the DPD force law to the cohesive energy densities of the pure fluids providing an alternative method of calculating the self-interaction parameters as well as a route to the cross-interaction parameter. We validate the new parameterization by modelling the binary system: SnI4/SiCl4, which displays liquid-liquid coexistence below an upper critical solution temperature around 140°C. A series of DPD simulations were conducted at a set of temperatures ranging from 0°C to above the experimental upper critical solution temperature using conservative parameters based on extrapolated experimental data. These simulations can be regarded as being equivalent to a quench from a high temperature to a lower one at constant volume. Our simulations recover the expected phase behaviour ranging from solid-liquid coexistence to liquid-liquid co-existence and eventually leading to a homogeneous single phase system. The results yield a binodal curve in close agreement with one predicted using regular solution theory, but, significantly, in closer agreement with actual solubility measurements

Narrative support for young game designers’ writing

Creating narrative-based computer games is a complex and challenging task. Narrative Threads is a suite of software tools designed to aid young people (aged 11-15) in creating their own narrative-based games as a writing development activity. A participatory design process highlighted the areas where additional support was required, and informed the iterative design of Narrative Threads. The tools are implemented as a plugin to a commercial game creation toolset, and constitute character and object design tools, a branching narrative diagramming tool and an augmented story map view. In this paper, we provide an overview of the design of the tools and describe an evaluation carried out with 14 children over a four-day workshop. The study examined tool usage patterns, and compared games created with Narrative Threads to those created using the standard toolset. The results suggest a number of ways in which dynamic external representations of story elements can support writing activities in narrative-based game creation. Young designers using Narrative Threads wrote more character dialogue, made stronger links between the conversations they wrote and wider game events, and designed more complex characters, compared to those using the standard toolset. In addition to showing how Narrative Threads can support young games designers, the results have broader implications for anyone looking to support storytelling and writing through game creation activities and tools

Matter effects in the D0-D0bar system

We discuss the impact of matter effects in the D0-D0bar system. We show that such effects could, in principle, be measured, but that they cannot be used to probe the mass difference x_D or the lifetime difference y_D. This occurs because the mixing effects and the matter effects decouple at short times. We also comment briefly on the B systems.Comment: 6 pages, RevTe

Impacto sobre a aprendizagem dos alunos: Perspectivas sobre a Comissão Nacional de Certificação de Professores

The purpose of this study is to report National Board Certified Teachers’ (NBCTs) perceived impact on student learning. The guiding research question for this study, “How do teachers perceive the influence of the National Board Certification process on student learning in their own classrooms?” was explored. A total of 496 NBCTs currently teaching in North Carolina public schools completed the survey questionnaire in which they responded to demographic questions, Likert item questions, and open-ended questions. More than 80% of the study’s participants reported the certification process had positively influenced student learning in their classrooms. Thematic analysis revealed several reoccurring themes that NBCTs reported having impact on student learning in their classrooms. These included impact on academic achievement, improved teaching, and/or an increase of effective evaluation and assessment strategies.El propósito de este estudio es informar sobre la percepción del impacto de la Comisión Nacional de Certificación Docente (por su sigla en inglés NBCTs) en el aprendizaje de los estudiantes. La pregunta de investigación que guía este estudio es "¿Cómo perciben los profesores la influencia del proceso de Certificación de la NBCTs en el aprendizaje de los estudiantes en las aulas de su país”. Un total de 496 docentes que cuentan con su NBCTs en las escuelas públicas de Carolina del Norte completó la encuesta en la que respondieron a preguntas demográficas, preguntas usando escalas Likert y preguntas abiertas. Más del ochenta por ciento de los participantes del estudio informó que el proceso de certificación ha influido positivamente en el aprendizaje de los estudiantes en sus clases. Análisis temático reveló varios temas recurrentes que los docentes NBCTs reportaron influyen en el aprendizaje de los estudiantes, incluidos rendimiento académico, mejora de la enseñanza, y/o un aumento de estrategias de evaluación y evaluación eficaces.O objetivo deste estudo é relatar sobre as percepções de impacto da Comissão Nacional de Certificação de Professores (sigla em Inglês NBCTs) nos aprendizagens dos alunos. A questão de pesquisa que orientou este estudo foi "Como é que os professores percebem a influência do processo de certificação NBCTs na aprendizagem dos alunos nas salas de aula do seu país". Um total de 496 professores têm seus NBCTs nas escolas públicas da Carolina do Norte responderam as perguntas sobre dados demográficos, perguntas usando uma escala Likert e perguntas abertas. Mais de oitenta por cento dos participantes do estudo relataram que o processo de certificação tem efeitos positivos na aprendizagem dos alunos em suas aulas. A análise temática revelou vários temas recorrentes que os professores NBCTs indicaram que influenciam a aprendizagem dos alunos, incluindo desempenho acadêmico, melhoras na educação, e/ou um aumento de estratégias de avaliação e de avaliação eficazes

Two Qubits in the Dirac Representation

A general two qubit system expressed in terms of the complete set of unit and fifteen traceless, Hermitian Dirac matrices, is shown to exhibit novel features of this system. The well-known physical interpretations associated with the relativistic Dirac equation involving the symmetry operations of time-reversal T, charge conjugation C, parity P, and their products are reinterpreted here by examining their action on the basic Bell states. The transformation properties of the Bell basis states under these symmetry operations also reveal that C is the only operator that does not mix the Bell states whereas all others do. In a similar fashion, expressing the various logic gates introduced in the subject of quantum computers in terms of the Dirac matrices shows for example, that the NOT gate is related to the product of time-reversal and parity operators.Comment: 11 page

Rare and Endangered Vetebrates of Ohio

Author Institution: U.S. Soil Conservation Service; Introductory Biology Program, The Ohio State University; School of Natural Resources, The Ohio State University; and Division of Wildlife, Ohio Department of Natural ResourcesThis paper, an annotated list of Ohio's rare and endangered vertebrate species, was compiled to supplement a similar national list and includes 10 mammals, 62 birds, 10 reptiles, 4 amphibians, and 33 fishes. Where possible, suggestions are made both as to causes of the rare or endangered status of these species and as to means of halting the trend. Ratings of endangered, rare, peripheral, or undetermined, as defined for the national classification, are given for each species

Results and recommendations from an intercomparison of six Hygroscopicity-TDMA systems

The performance of six custom-built Hygrocopicity-Tandem Differential Mobility Analyser (H-TDMA) systems was investigated in the frame of an international calibration and intercomparison workshop held in Leipzig, February 2006. The goal of the workshop was to harmonise H-TDMA measurements and develop recommendations for atmospheric measurements and their data evaluation. The H-TDMA systems were compared in terms of the sizing of dry particles, relative humidity (RH) uncertainty, and consistency in determination of number fractions of different hygroscopic particle groups. The experiments were performed in an air-conditioned laboratory using ammonium sulphate particles or an external mixture of ammonium sulphate and soot particles. The sizing of dry particles of the six H-TDMA systems was within 0.2 to 4.2% of the selected particle diameter depending on investigated size and individual system. Measurements of ammonium sulphate aerosol found deviations equivalent to 4.5% RH from the set point of 90% RH compared to results from previous experiments in the literature. Evaluation of the number fraction of particles within the clearly separated growth factor modes of a laboratory generated externally mixed aerosol was done. The data from the H-TDMAs was analysed with a single fitting routine to investigate differences caused by the different data evaluation procedures used for each H-TDMA. The differences between the H-TDMAs were reduced from +12/-13% to +8/-6% when the same analysis routine was applied. We conclude that a common data evaluation procedure to determine number fractions of externally mixed aerosols will improve the comparability of H-TDMA measurements. It is recommended to ensure proper calibration of all flow, temperature and RH sensors in the systems. It is most important to thermally insulate the aerosol humidification unit and the second DMA and to monitor these temperatures to an accuracy of 0.2 degrees C. For the correct determination of external mixtures, it is necessary to take into account size-dependent losses due to diffusion in the plumbing between the DMAs and in the aerosol humidification unit.Peer reviewe

How good are your fits? Unbinned multivariate goodness-of-fit tests in high energy physics

Multivariate analyses play an important role in high energy physics. Such analyses often involve performing an unbinned maximum likelihood fit of a probability density function (p.d.f.) to the data. This paper explores a variety of unbinned methods for determining the goodness of fit of the p.d.f. to the data. The application and performance of each method is discussed in the context of a real-life high energy physics analysis (a Dalitz-plot analysis). Several of the methods presented in this paper can also be used for the non-parametric determination of whether two samples originate from the same parent p.d.f. This can be used, e.g., to determine the quality of a detector Monte Carlo simulation without the need for a parametric expression of the efficiency.Comment: 32 pages, 12 figure