Influence of hysteresis on tidal capillary fringe dynamics in a well-sorted sand

Nielsen and Perrochet [Adv. Water Resour. 23 (2000) 503] presented experimental data for cyclic water movement in the vadose zone above an oscillating watertable. The response of the watertable to cyclic forcing was characterised by the ratios of the forcing head to watertable amplitudes and their associated phase lag. They found that their non-hysteretic Richards' equation model failed to represent the observed behaviour of these parameters. This paper explores the effect on the simulated capillary fringe dynamics (in terms of these parameters) of including varying degrees of hysteresis in the moisture retention curve used in a numerical model of their experiment. It is clear that hysteresis can indeed account for observed discrepancies between simulation and experiment and that the effect of hysteresis varies with the frequency of oscillation. The use of a single-valued mean retention curve, as advocated by some authors, fails to provide a match between the simulated and observed behaviour of the Nielsen and Perrochet parameters, but is shown to be adequate for predicting time-averaged soil moisture profiles. (C) 2003 Elsevier Ltd. All rights reserved.

Genotype and environment effects on dynamics of harvest index during grain filling in sorghum

An approach based on a linear rate of increase in harvest index (141) with time after anthesis has been used as a simple means-to predict grain growth and yield in many crop simulation models. When applied to diverse situations, however, this approach has been found to introduce significant error in grain yield predictions. Accordingly, this study was undertaken to examine the stability of the HI approach for yield prediction in sorghum [Sorghum bicolor (L.) Moench]. Four field experiments were conducted under nonlimiting water. and N conditions. The experiments were sown at times that ensured a broad range in temperature and radiation conditions. Treatments consisted of two population densities and three genotypes varying in maturity. Frequent sequential harvests were used to monitor crop growth, yield, and the dynamics of 111. Experiments varied greatly in yield and final HI. There was also a tendency for lower HI with later maturity. Harvest index dynamics also varied among experiments and, to a lesser extent, among treatments within experiments. The variation was associated mostly with the linear rate of increase in HI and timing of cessation of that increase. The average rate of HI increase was 0.0198 d(-1), but this was reduced considerably (0.0147) in one experiment that matured in cool conditions. The variations found in IN dynamics could be largely explained by differences in assimilation during grain filling and remobilization of preanthesis assimilate. We concluded that this level of variation in HI dynamics limited the general applicability of the HI approach in yield prediction and suggested a potential alternative for testing.

SPAnDX: a process-based population dynamics model to explore management and climate change impacts on an invasive alien plant, Acacia nilotica

This paper describes a process-based metapopulation dynamics and phenology model of prickly acacia, Acacia nilotica, an invasive alien species in Australia. The model, SPAnDX, describes the interactions between riparian and upland sub-populations of A. nilotica within livestock paddocks, including the effects of extrinsic factors such as temperature, soil moisture availability and atmospheric concentrations of carbon dioxide. The model includes the effects of management events such as changing the livestock species or stocking rate, applying fire, and herbicide application. The predicted population behaviour of A. nilotica was sensitive to climate. Using 35 years daily weather datasets for five representative sites spanning the range of conditions that A. nilotica is found in Australia, the model predicted biomass levels that closely accord with expected values at each site. SPAnDX can be used as a decision-support tool in integrated weed management, and to explore the sensitivity of cultural management practices to climate change throughout the range of A. nilotica. The cohort-based DYMEX modelling package used to build and run SPAnDX provided several advantages over more traditional population modelling approaches (e.g. an appropriate specific formalism (discrete time, cohort-based, process-oriented), user-friendly graphical environment, extensible library of reusable components, and useful and flexible input/output support framework). (C) 2003 Published by Elsevier Science B.V.

Performing race, culture, and gender in an Indigenous Australian women's music and dance classroom

One perpetual concern among Indigenous Australian peoples is authenticity of voice. Who has the right to speak for, and to make representations about, the knowledges and cultures of Indigenous Australian peoples? Whose voice is more authentic, and what happens to these ways of knowing when they make the journey into mainstream Western academic classrooms? In this paper, I examine these questions within the politics of ���doing��� Indigenous Australian studies by focusing on my own experiences as a lecturer in the Aboriginal and Torres Strait Islander Studies Unit at the University of Queensland. My findings suggest that representation is a matter of problematizing positionality and, from a pedagogical standpoint, being aware of, and willing to address, the ways in which power, authority, and voice are performed and negotiated as teachers and learners of Indigenous Australian studies.

Pr��ticas e saberes da professora pomerana : um estudo sobre interculturalidade

Esta pesquisa analisa pr��ticas e saberes da professora pomerana em uma escola do campo de ensino fundamental em Santa Maria de Jetib��/Estado do Esp��rito Santo/Brasil, para problematizar quest��es sobre cultura e interculturalidade. Aprofundam-se reflex��es sobre quais t��m sido as contribui����es dessas pr��ticas para uma educa����o escolar intercultural. Beneficia-se do estudo de caso para an��lise de documentos, observa����es de aulas, observa����es participantes em planejamentos, realiza����o de entrevista semiestruturada com a professora e, anota����es no di��rio de campo. Situam-se brevemente quest��es da hist��ria dos descendentes de pomeranos, bem como sobre as principais produ����es acad��micas referentes �� educa����o desse povo tradicional. Discuss��es te��rico-metodol��gicas contribuem para compreens��o e embasamento de alguns conceitos-chave, como: cultura(s) (THOMPSON, 1995; GEERTZ, 2012), interculturalismo (CANDAU, 2005; FORNET-BETANCOURT, 2004), cultura escolar e cultura da escola (FORQUIN, 1993), pr��ticas docentes (FREIRE, 1996), saberes docentes (TARDIF, 2012), parceria (FOERSTE, 2005) etc. Aponta-se que as pr��ticas da professora pomerana faziam parte do contexto escolar antes da implementa����o do Programa de Educa����o Escolar Pomerana (PROEPO) no que se refere ao uso oral da l��ngua pomerana na sala de aula. As pr��ticas da professora se ressignificam na intera����o com os saberes culturais, experienciais e coletivos produzidos na din��mica escolar e comunit��ria. Essas pr��ticas possibilitam o di��logo da cultura escolar com a cultura da escola, promovendo a viv��ncia das experi��ncias locais e o acesso ao saber universal. Pode-se afirmar que no contexto da escola investigada existem algumas condi����es que favorecem a dimens��o da interculturalidade nos processos pedag��gicos. Cabe aprofundar estudos sobre as contribui����es da educa����o escolar para o ensino bil��ngue e seus impactos �� valoriza����o da cultura pomerana e a consequente manuten����o da l��ngua deste povo tradicional. Tens��es e conflitos foram identificados quanto ao enfoque do PROEPO ao desenvolvimento das habilidades de leitura e escrita em l��ngua pomerana.

Curr��culo e educa����o especial : as a����es da escola a partir dos di��logos cotidianos

O estudo teve como objetivo investigar as a����es constitu��das por uma escola p��blica de Ensino Fundamental para o envolvimento de alunos com defici��ncia e com transtornos globais do desenvolvimento no curr��culo escolar. Contou com as contribui����es te��ricas de Boaventura de Sousa Santos, Michel de Certeau e Philippe Meirieu para uma discuss��o sociol��gica, filos��fica e pedag��gica das situa����es desencadeadas pela pesquisa. No campo do curr��culo, aproximou-se das teoriza����es de Silva, Moreira, Apple e Sacrist��n, dentre outros, por serem te��ricos que analisam o trabalho com o conhecimento no contexto escolar. J�� no campo da Educa����o Especial, dialogou com as produ����es de pesquisadores que postulam pela ideia de que o processo de inclus��o escolar pressup��e acesso �� escola, bem como perman��ncia e a garantia do direito de apropria����o dos conhecimentos socialmente produzidos. Como aporte te��rico-metodol��gico, apoiou-se nos pressupostos da pesquisa-a����o colaborativo-cr��tica que advoga pela possibilidade de, por meio da pesquisa cient��fica, produzir conhecimento sobre a realidade social, promover mudan��as nas situa����es desafiadoras e envolver os sujeitos pesquisados em processos de forma����o continuada em contexto. O trabalho de pesquisa foi realizado em uma escola de Ensino Fundamental, pertencente �� Rede P��blica Municipal de Ensino de Vila Velha/ES, envolvendo professores, pedagogos, dirigente escolar, respons��veis pelos discentes e alunos matriculados do 1�� ao 6�� ano do Ensino Fundamental. O processo de produ����o de dados se efetivou no per��odo de julho de 2010 a julho de 2011. O pesquisador esteve tr��s vezes por semana no campo de pesquisa, participando das interven����es em sala de aula, dos espa��os para planejamento e forma����o continuada e tamb��m de momentos informais na entrada, recreio e sa��da dos alunos. Para o desenvolvimento do estudo, trabalhou-se com tr��s frentes correlacionadas: a observa����o participante e a escuta dos discursos produzidos por alunos, professores, equipe t��cnico-pedag��gica e respons��veis pelos discentes sobre o envolvimento dos estudantes com indicativos �� Educa����o Especial no curr��culo escolar; a constitui����o de espa��os de forma����o continuada, tomando os dados produzidos na primeira etapa do estudo como elementos de sustenta����o da din��mica formativa; o acompanhamento das a����es praticadas pela escola para envolvimento das necessidades educacionais dos alunos com indicativos �� Educa����o Especial no curr��culo escolar, a partir das reflex��es desencadeadas nos espa��os de forma����o continuada. Como resultados, a pesquisa aponta a necessidade de advogar pela constitui����o de curr��culos escolares mais abertos para contemplar as necessidades de aprendizagem de alunos com comprometimentos f��sicos, ps��quicos, intelectuais ou sensoriais. Esta pesquisa se distancia de l��gicas que defendem a flexibiliza����o curricular como um esvaziamento do curr��culo em nome das condi����es existenciais dos alunos. Entende que, entre o curr��culo escolar e a produ����o de conhecimentos pelos alunos com indicativos �� Educa����o Especial, h�� uma pluralidade de situa����es que precisam ser problematizadas pela escola: a leitura produzida sobre a aprendizagem dos alunos; a falta de conhecimento sobre a sexualidade humana; os desafios presentes na rela����o fam��lia e escola; e os pressupostos da normalidade/anormalidade. Esses fatores podem se configurar como elementos que impedem que os alunos obtenham sucesso em sua jornada educativa, por��m, em contrapartida, podem ser utilizados como quest��es a subsidiar espa��os de forma����o continuada. O estudo aponta que, por meio de atitudes colaborativas e cr��ticas entre os profissionais da escola, �� poss��vel articular a����es que garantam o direito de aprender do estudante com defici��ncia e com transtornos globais do desenvolvimento na escola de ensino comum.

An outline of military technological dynamics as restraints for acquisition, international cooperation and domestic technological development

The expectation that technological returns from defense expenditure through acquisition, international cooperation and domestic research would further national development underappreciates the different technological dynamic of the armed services. This paper outlines the technological dynamic the stems from fighting in the air, at sea and on land, exemplifying consequences for the case of acquisition.

Molecular dynamics computer simulation of scratch resistance testing of polymers: visualization

Experimental scratch resistance testing provides two numbers: the penetration depth Rp and the healing depth Rh. In molecular dynamics computer simulations, we create a material consisting of N statistical chain segments by polymerization; a reinforcing phase can be included. Then we simulate the movement of an indenter and response of the segments during X time steps. Each segment at each time step has three Cartesian coordinates of position and three of momentum. We describe methods of visualization of results based on a record of 6NX coordinates. We obtain a continuous dependence on time t of positions of each of the segments on the path of the indenter. Scratch resistance at a given location can be connected to spatial structures of individual polymeric chains.

Polymer indentation with mesoscopic molecular dynamics

Indentation tests are used to determine the hardness of a material, e.g., Rockwell, Vickers, or Knoop. The indentation process is empirically observed in the laboratory during these tests; the mechanics of indentation is insufficiently understood. We have performed first molecular dynamics computer simulations of indentation resistance of polymers with a chain structure similar to that of high density polyethylene (HDPE). A coarse grain model of HDPE is used to simulate how the interconnected segments respond to an external force imposed by an indenter. Results include the time-dependent measurement of penetration depth, recovery depth, and recovery percentage, with respect to indenter force, indenter size, and indentation time parameters. The simulations provide results that are inaccessible experimentally, including continuous evolution of the pertinent tribological parameters during the entire indentation process.

Simulating scratch behavior of polymers with mesoscopic molecular dynamics

Part replacement and repair is needed in structures with moving parts because of scratchability and wear. In spite of some accumulation of experimental evidence, scratch resistance is still not well understood. We have applied molecular dynamics to study scratch resistance of amorphous polymeric materials through computer simulations. As a first approach, a coarse grain model was created for high density polyethylene at the mesoscale. We have also extended the traditional approach and used real units rather than reduced units (to our knowledge, for the first time), which enable an improved quantification of simulation results. The obtained results include analysis of penetration depth, residual depth and recovery percentage related to indenter force and size. Our results show there is a clear effect from these parameters on the tribological properties. We also discuss a "crooked smile" effect on the scratched surface and the reasons for its appearance.

Pectus Excavatum postsurgical outcome based on preoperative soft body dynamics simulation

Pectus excavatum is the most common congenital deformity of the anterior chest wall, in which an abnormal formation of the rib cage gives the chest a caved-in or sunken appearance. Today, the surgical correction of this deformity is carried out in children and adults through Nuss technic, which consists in the placement of a prosthetic bar under the sternum and over the ribs. Although this technique has been shown to be safe and reliable, not all patients have achieved adequate cosmetic outcome. This often leads to psychological problems and social stress, before and after the surgical correction. This paper targets this particular problem by presenting a method to predict the patient surgical outcome based on pre-surgical imagiologic information and chest skin dynamic modulation. The proposed approach uses the patient pre-surgical thoracic CT scan and anatomical-surgical references to perform a 3D segmentation of the left ribs, right ribs, sternum and skin. The technique encompasses three steps: a) approximation of the cartilages, between the ribs and the sternum, trough b-spline interpolation; b) a volumetric mass spring model that connects two layers - inner skin layer based on the outer pleura contour and the outer surface skin; and c) displacement of the sternum according to the prosthetic bar position. A dynamic model of the skin around the chest wall region was generated, capable of simulating the effect of the movement of the prosthetic bar along the sternum. The results were compared and validated with patient postsurgical skin surface acquired with Polhemus FastSCAN system

Network dynamics in scientific knowledge acquisition: an analysis in three public universities in the state of Bahia

This paper aims to cast some light on the dynamics of knowledge networks in developing countries by analyzing the scientific production of the largest university in the Northeast of Brazil and its influence on some of the remaining regional research institutions in the state of Bahia. Using a methodology test to be employed in a larger project, the Universidade Federal da Bahia (UFBA) (Federal University of Bahia), the Universidade do Estado da Bahia (Uneb) (State of Bahia University) and the Universidade Estadual de Santa Cruz (Uesc)'s (Santa Cruz State University) scientific productions are discussed in one of their most traditionally expressive sectors in academic production - namely, the field of chemistry, using social network analysis of co-authorship networks to investigate the existence of small world phenomena and the importance of these phenomena in research performance in these three universities. The results already obtained through this research bring to light data of considerable interest concerning the scientific production in unconsolidated research universities. It shows the important participation of the UFBA network in the composition of the other two public universities research networks, indicating a possible occurrence of small world phenomena in the UFBA and Uesc networks, as well as the importance of individual researchers in consolidating research networks in peripheral universities. The article also hints that the methodology employed appears to be adequate insofar as scientific production may be used as a proxy for scientific knowledge.