Letteratura scientifica selezionata sul tema "Expression problem"
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Articoli di riviste sul tema "Expression problem"
1
Mukhamedova, Nigora. "THE PROBLEM OF EXPRESSION NON-CATEGORICAL STATEMENTS IN LINGUISTIC TEXTS." INTERNATIONAL JOURNAL OF WORD ART 3, no. 3 (March 30, 2020): 91–97. http://dx.doi.org/10.26739/2181-9297-2020-3-13.
Testo completoAbstract (sommario):
The article deals with the issues based on the study of non-categorical statements in a linguistic text in modern English. The essence of scientific communication is a message, or the transmission by means of language of some mental content, including the expression of an intellectual-evaluative attitude to the subject of speech. The content of intellectual assessments is conditioned by knowledge and experience of intellectual and material activities of people.In a scientific text, this attitude can be the result of verifying the truth of what is expressed by the author himself or by another scientist or a team of researchers, as well as confirmation or refutation of apreviously formed assessment that served as the basis for further discussion
2
Diveev, A. I., and E. A. Sofronova. "Machine Search Problem for Mathematical Expression." Doklady Mathematics 110, S1 (December 2024): S25—S34. https://doi.org/10.1134/s1064562424602087.
Testo completoAbstract (sommario):
Abstract The problem of searching for a mathematical expression is formulated. Classes of mathematical problems where this problem is in demand are presented. A general approach to solving this problem based on machine learning using symbolic regression methods is given. This approach allows finding not only the parameters of the desired mathematical expression, but also its structure. The general problem of machine learning by methods of symbolic regression is described and a unified approach to overcoming it based on the application of the principle of small variations of the basis solution is given.
3
Roy, Subhro, and Dan Roth. "Mapping to Declarative Knowledge for Word Problem Solving." Transactions of the Association for Computational Linguistics 6 (December 2018): 159–72. http://dx.doi.org/10.1162/tacl_a_00012.
Testo completoAbstract (sommario):
Math word problems form a natural abstraction to a range of quantitative reasoning problems, such as understanding financial news, sports results, and casualties of war. Solving such problems requires the understanding of several mathematical concepts such as dimensional analysis, subset relationships, etc. In this paper, we develop declarative rules which govern the translation of natural language description of these concepts to math expressions. We then present a framework for incorporating such declarative knowledge into word problem solving. Our method learns to map arithmetic word problem text to math expressions, by learning to select the relevant declarative knowledge for each operation of the solution expression. This provides a way to handle multiple concepts in the same problem while, at the same time, supporting interpretability of the answer expression. Our method models the mapping to declarative knowledge as a latent variable, thus removing the need for expensive annotations. Experimental evaluation suggests that our domain knowledge based solver outperforms all other systems, and that it generalizes better in the realistic case where the training data it is exposed to is biased in a different way than the test data.
4
Lin, Xin, Zhenya Huang, Hongke Zhao, Enhong Chen, Qi Liu, Hao Wang, and Shijin Wang. "HMS: A Hierarchical Solver with Dependency-Enhanced Understanding for Math Word Problem." Proceedings of the AAAI Conference on Artificial Intelligence 35, no. 5 (May 18, 2021): 4232–40. http://dx.doi.org/10.1609/aaai.v35i5.16547.
Testo completoAbstract (sommario):
Automatically solving math word problems is a crucial task for exploring the intelligence levels of machines in the general AI domain. It is highly challenging since it requires not only natural language understanding but also mathematical expression inference. Existing solutions usually explore sequence-to-sequence models to generate expressions, where the problems are simply encoded sequentially. However, such models are generally far from enough for understanding problems as similar to humans and lead to incorrect answers. To this end, in this paper, we propose a novel Hierarchical Math Solver (HMS) to make deep understanding and exploitation of problems. In problem understanding, imitating human reading habits, we propose a hierarchical word-clause-problem encoder. Specifically, we first split each problem into several clauses and learn problem semantics from the local clause level to the global problem level. Then, in clause understanding, we propose a dependency-based module to enhance clause semantics with the dependency structure of the problem. Next, in expression inference, we propose a novel tree-based decoder to generate the mathematical expression for the answer. In the decoder, we apply a hierarchical attention mechanism to enhance the problem semantics with context from different levels, and a pointer-generator network to guide the model to copy existing information and infer extra knowledge. Extensive experimental results on two widely used datasets demonstrate that HMS achieves not only better answers but also more reasonable inference.
5
Clemons, Bil. "Solving the Membrane Protein Expression Problem." Biophysical Journal 112, no. 3 (February 2017): 329a—330a. http://dx.doi.org/10.1016/j.bpj.2016.11.1783.
Testo completo
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Peng, Xiangyang, Wei Liu, and Jinrong Shen. "A class of constrained inverse eigenvalue problem and associated approximation problem for symmetrizable matrices." Filomat 33, no. 7 (2019): 1903–9. http://dx.doi.org/10.2298/fil1907903p.
Testo completoAbstract (sommario):
The real symmetric matrix is widely applied in various fields, transforming non-symmetric matrix to symmetric matrix becomes very important for solving the problems associated with the original matrix. In this paper, we consider the constrained inverse eigenvalue problem for symmetrizable matrices, and obtain the solvability conditions and the general expression of the solutions. Moreover, we consider the corresponding optimal approximation problem, obtain the explicit expressions of the optimal approximation solution and the minimum norm solution, and give the algorithm and corresponding computational example.
7
Mamiyeva, Turkan. "Solving the Cauchy and Boundary Value Problem for a Continuous Multiplicative Differential Equation of the Second Order." Euroasia Journal of Mathematics, Engineering, Natural & Medical Sciences 11, no. 35 (September 25, 2024): 30–33. https://doi.org/10.5281/zenodo.13884817.
Testo completoAbstract (sommario):
In the presented work, the Cauchy and boundary value problem for the inhomogeneous equation with the second order multiplicative derivative in the case of discontinuity is considered. The general solution of the considered equation, which depends on two arbitrary constants, has been obtained. Then, when looking at the Cauchy problem, these arbitrary constants are determined from the given initial conditions, and when looking at the boundary problem, these arbitrary constants are determined from the given boundary conditions. Thus, analytical expressions have been obtained for the solution of the problems considered both in the Cauchy problem and in the boundary problem. Moreover, in the continuous case, an analytical expression has been obtained for the solution of the Cauchy and boundary problem considered for the second formulation multiplicative derivative inhomogeneous differential equation. Thus, all seven algebraic operations and integration operations are involved in this analytical expression.
8
Ludlow, Peter. "Cognitive dynamics: Red Queen semantics versus the story of O." Belgrade Philosophical Annual 35, no. 2 (2022): 53–67. http://dx.doi.org/10.5937/bpa2202053l.
Testo completoAbstract (sommario):
It appears that indexicals must have fine-grained senses for us to explain things involving human action and emotions, and we typically identify these different senses with different modes of expression. On the other hand, we also express the very same thought in very different ways. The first problem is the problem of cognitive significance. The second problem is what Branquinho (1999) has called the problem of cognitive dynamics. The question is how we can solve both of those problems at the same time. Vojislav Božičković (2021) offers one solution in which the cognitive dynamics runs through the objects of the attitudes. I discuss this solution and offer an alternative in which the theory of cognitive dynamics has no use for the objects of the attitudes to unify expressions of attitudes. When we say or believe "the same thing" using different modes of expressions, it is by virtue of our deploying a dynamic theory of attitude expression. Like Lewis Carrol's Red Queen, we must run to stay in place.
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Cruz, Dalia. "Oral expression: a problem to be addressed." SCIÉNDO 23, no. 4 (December 31, 2020): 293–98. http://dx.doi.org/10.17268/sciendo.2020.035.
Testo completo
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Chen, Brayden. "A New Method to Explore the Integer Partition Problem." International Journal on Cybernetics & Informatics 12, no. 04 (July 27, 2023): 75–83. http://dx.doi.org/10.5121/ijci.2023.120406.
Testo completoAbstract (sommario):
Integer Partition is a well known difficult problem in number theory and no solid solution has been found until today. The authors used Linear Difference Equation and Root of Unity to successfully get the expressions for integer n when the group number is k=2, k=3, k=4 and k=5. This proves the close relationship between integer partition and root of unity. With the analysis, it can be concluded that there will be an expression of U(n,k) existing for any n and k and we have found a method to develop the expression. Also this has provided a new interesting method to do further research in the integer partition area.
Tesi sul tema "Expression problem"
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Sias, James Bar-On Dorit. "How the nature of expression constitutes a problem for expressivism." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2009. http://dc.lib.unc.edu/u?/etd,2279.
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Thesis (M.A.)--University of North Carolina at Chapel Hill, 2009.<br>Title from electronic title page (viewed Jun. 26, 2009). "... in partial fulfillment of the requirements for the degree of Master of Arts in the Department of Philosophy." Discipline: Philosophy; Department/School: Philosophy.
2
Henderson, Ian. "Solving the inclusion body problem - a case study : high level expression of TEM-1 #beta#-lactamase in Escherichia coli." Thesis, University of Warwick, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282432.
Testo completo
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Hooper, Emma G. "Maternal Emotion Expression, Depressive Symptoms, and Stress: Profiles in Relation to Child Emotion Socialization and Problem Behavior." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1374094882.
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Seefried, Sean Computer Science & Engineering Faculty of Engineering UNSW. "Language extension via dynamically extensible compilers." Awarded by:University of New South Wales. Computer Science and Engineering, 2006. http://handle.unsw.edu.au/1959.4/29524.
Testo completoAbstract (sommario):
This dissertation provides the motivation for and evidence in favour of an approach to language extension via dynamic loading of plug-ins. There is a growing realisation that language features are often a superior choice to software libraries for implementing applications. Among the benefits are increased usability, safety and efficiency. Unfortunately, designing and implementing new languages is difficult and time consuming. Thus, reuse of language infrastructure is an attractive implementation avenue. The central question then becomes, what is the best method to extend languages? Much research has focussed on methods of extension based on using features of the language itself such as macros or reflection. This dissertation focuses on a complementary solution: plug-in compilers. In this approach languages are extended at run-time via dynamic extensions to compilers, called plug-ins. Plug-ins can be used to extend the expressiveness, safety and efficiency of languages. However, a plug-in compiler provides other benefits. Plug-in compilers encourage modularity, lower the barrier of entry to development, and facilitate the distribution and use of experimental language extensions. This dissertation describes how plug-in support is added, to both the front and back-end of a compiler, and demonstrates their application through a pair of case studies.
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Erdogdu, Utku. "Efficient Partially Observable Markov Decision Process Based Formulation Of Gene Regulatory Network Control Problem." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614317/index.pdf.
Testo completoAbstract (sommario):
The need to analyze and closely study the gene related mechanisms motivated the
research on the modeling and control of gene regulatory networks (GRN). Dierent
approaches exist to model GRNs<br>they are mostly simulated as mathematical models
that represent relationships between genes. Though it turns into a more challenging
problem, we argue that partial observability would be a more natural and realistic
method for handling the control of GRNs. Partial observability is a fundamental
aspect of the problem<br>it is mostly ignored and substituted by the assumption that
states of GRN are known precisely, prescribed as full observability. On the other hand,
current works addressing partially observability focus on formulating algorithms for
the nite horizon GRN control problem. So, in this work we explore the feasibility of
realizing the problem in a partially observable setting, mainly with Partially Observable
Markov Decision Processes (POMDP). We proposed a POMDP formulation for
the innite horizon version of the problem. Knowing the fact that POMDP problems
suer from the curse of dimensionality, we also proposed a POMDP solution method
that automatically decomposes the problem by isolating dierent unrelated parts of
the problem, and then solves the reduced subproblems. We also proposed a method
to enrich gene expression data sets given as input to POMDP control task, because
in available data sets there are thousands of genes but only tens or rarely hundreds of
samples. The method is based on the idea of generating more than one model using
the available data sets, and then sampling data from each of the models and nally
ltering the generated samples with the help of metrics that measure compatibility,
diversity and coverage of the newly generated samples.
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WENJING, ZHU. "CARRY A LIFE : The Exploration of How Carrying Affects The Expression of Wearing." Thesis, Högskolan i Borås, Institutionen Textilhögskolan, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-17712.
Testo completoAbstract (sommario):
Interested by the relation of function and fashion expression, this project choose ‘carry’ as an example function to dive in. It explores how ‘carry’ affects the expression of wearing and how it can be interpret into fashion expression. The research question - what do we carry in life - gives the foundation in the developing of an aesthetic for sustaining. Problem solving was the methodology that I adopted from Industrial design. Together with other methods, it helped me in deign rationale. During the exploration, ‘carry’ is analyzed, decomposed and translated into a conceptual collection. The interpretation of ‘carry’ is not functional oriented or literal-symbol inspired. The dynamic moment of functioning is more of the focus rather than a static expression of garment. In addition, minimized fashion expression is also discussed as the aesthetic of sustainability.<br>Program: Modedesignutbildningen
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Ralić, Sara. "Interprétation et traduction d’expressions figées du français vers le serbe dans un corpus littéraire contemporain." Thesis, Paris 4, 2015. http://www.theses.fr/2015PA040196.
Testo completoAbstract (sommario):
Cette thèse propose une analyse de l’expression figée en tant que signe linguistique complexe, stable, variable et dynamique et en tant que problème de traduction à partir d’un corpus composé d’œuvres littéraires contemporaines françaises et de leurs traductions serbes. Le discours met en évidence la distance entre la signification du modèle et le sens de l’expression figée sémantiquement accomplie imbriquée dans le texte, dont l’une des réalisations est le défigement qui, lui, ne consiste simplement pas à renverser les critères syntaxiques, mais à élaborer un nouveau signifié de synthèse au service des stratégies discursives de l’énonciateur. Ce travail identifie les mécanismes linguistiques propres à l’expression figée et incontournables dans l’acte de traduire, ainsi que les incompatibilités entre les problèmes de sa traduction et certaines propriétés qui lui sont attribuées. Les problèmes que pose la traduction de l’expression figée dans le texte littéraire, dont elle façonne la progression narrative, excèdent la dichotomie entre la solution éthique et la solution ethnologique. Ils relèvent de la façon dans le locuteur établit le lien entre la conceptualisation inhérente à l’expression figée, elle-même construite sur la base des concepts préexistants - d’où l’image mentale et la charge connotative -, et la réalité à laquelle il l’applique. Sa traduction, eu égard à sa complexité pragma-sémantique, exige forcément une approche sourcière dans la phase interprétative et une solution cibliste<br>This thesis proposes an analysis of a phraseme as a complex, stable, variable and dynamic linguistic sign, and as a translation problem based on a corpus of contemporary French literature and its Serbian translations. The discourse highlights the distance between the meaning of a model and the meaning of a phraseme that is semantically accomplished and embedded in a text. One of its possible realizations is a pun that does not only consist in transgressing the syntactic criteria but in developing a new global signified, serving the speaker’s discursive strategies. This work identifies linguistic mechanisms specific to lexical frozenness that are inevitable in the act of translation, and incompatibilities between the problems of translation and properties of a given phraseme. Its translation problems in a literary text, whose narrative progression it shapes, exceed the dichotomy between a domesticated translation and a foreignized translation. Translation problems result from the way in which the speaker establishes the link between the conceptualization inherent to a phraseme, built itself on the basis of pre-existing concepts - hence the mental image and the connotative surplus value - and the reality to which the speaker applies it. Its translation, given its pragma-semantic complexity, necessarily requires a source-oriented approach in the interpretative phase and a target-oriented solution
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Checcucci, Érica de Sousa. "Ensino-aprendizagem de BIM nos cursos de graduação em engenharia civil e o papel da expressão gráfica neste contexto." Faculdade de Educação, 2014. http://repositorio.ufba.br/ri/handle/ri/15295.
Testo completoAbstract (sommario):
Submitted by Érica Checcucci (erica.checcucci@univasf.edu.br) on 2014-05-03T15:04:50Z
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TESE -final - 17_4.pdf: 5511812 bytes, checksum: 7bf4dece9310718a9ad7f50bcb5dfc7c (MD5)<br>UNIVASF - Universidade Federal do Vale do São Francisco. FAPESB - Fundação de Amparo à Pesquisa do Estado da Bahia.<br>Resumo: O objetivo deste trabalho é contribuir para a adoção de BIM (Modelagem da Informação da Construção) nos cursos de graduação em Engenharia Civil. Para tal, é feita uma análise sobre o paradigma BIM e sobre experiências nacionais e internacionais de ensino-aprendizagem sobre o tema; são identificadas competências necessárias para se trabalhar com BIM; são investigados que elementos esta modelagem pode trazer para a configuração instrumental e cognitiva do estudante; são apresentados métodos e estratégias de ensino-aprendizagem que se mostram adequados para trabalhar com o contexto BIM. A partir dos estudos efetuados, é desenvolvido um método para identificar interfaces entre o currículo do engenheiro civil e BIM, mapeando momentos da formação do aluno nos quais esta modelagem pode ser discutida e trabalhada. Finalmente, a pesquisa volta-se para investigar a Expressão Gráfica (EG) e cria uma proposta para estruturação desta área dentro de um currículo de engenharia civil que adote o BIM. O trabalho desenvolvido é exploratório, qualitativo, de natureza fenomenológica e utilizou como pressupostos a implicação do pesquisador, o rigor da pesquisa qualitativa e o paradigma da complexidade. Dentre os seus principais resultados, pode ser ressaltado que: (a) a adoção do paradigma BIM demanda a atualização dos cursos de engenharia civil, o que envolve também a formação de docentes para se trabalhar com o tema; (b) experiências de sucesso vem sendo feitas tanto no Brasil como no exterior e mostram que não apenas é possível trabalhar BIM na graduação, como ele tem trazido diversas vantagens para o aprendizado de conteúdos de engenharia e o desenvolvimento cognitivo dos estudantes; (c) é importante planejar a implantação de BIM considerando o contexto específico de cada instituição e curso; (d) cursos que tem entre seus objetivos inserir BIM nos processos de ensino-aprendizagem devem buscar promover um alto grau de integração entre disciplinas e fomentar o trabalho colaborativo entre docentes; (e) para que aconteça um aprendizado integrado e contínuo, deve-se trabalhar BIM em diversos componentes curriculares ao longo do curso; (f) para que a área de EG possa contribuir para a formação do engenheiro civil em BIM, seu escopo deve ser ampliado, incluindo não apenas o desenho (2D) e a modelagem geométrica (3D) mas também abrangendo a compreensão de informações multidimensionais, multimodais e abstratas; (g) esta área pode trabalhar com os alunos uma pequena parte do amplo contexto BIM, no entanto fornecendo insumos para que os estudantes construam uma base sólida a partir da qual possam desenvolver as competências necessárias para trabalhar com esta modelagem, e finalmente, (h) o processo de ensino-aprendizagem de BIM será mais sólido se for continuado durante toda a formação do estudante, iniciando-se logo no seu acesso à universidade e nas disciplinas do núcleo básico.<br>Abstract: The purpose of this study is to contribute to the adoption of BIM (Building Information Modeling) in undergraduate courses in Civil Engineering. To this end, an analysis of the BIM paradigm and of national and international experiences in teaching and learning of the subject is made; necessary skills to work with BIM are identified, and the elements that this modeling can bring to the student cognition are investigated. Strategies to deploy BIM courses in civil engineering education and methods of teaching and learning that prove suitable to work with BIM context are presented. From the studies conducted, a method is developed to identify interfaces between the Civil Engineer curriculum and BIM, mapping moments of student education in which this modeling can be discussed and worked out. Finally, the research turns to investigate the Graphic Expression and creates a proposal for structuring this area within a civil engineering curriculum that adopts BIM. The work is exploratory, has a phenomenological nature and assumptions of the implication of the researcher, the rigor of qualitative research and the complexity paradigm. Among the main results, it can be noted that: (a) the adoption of BIM paradigm demand updating courses in civil engineering, which also involves the training of teachers for working with the theme; (b) some success experiences have been achieved both in Brazil and abroad and show that BIM can be studied not only in graduation course, but it has also brought several advantages for learning engineering content and cognitive development of students; (c) it is important to create a plan for implementation of BIM, considering the specific context of each institution and course; (d) courses that have among its objectives work with BIM should seek to promote a high degree of integration between disciplines and foster collaborative work among teachers; (e) to make an integrated and continuous learning, BIM should be worked in various curriculum components along the course; (f) for the GE contribute to the formation of the civil engineering in BIM, its scope should be expanded, including not only the (2D) design and (3D) geometric modeling but also encompassing the understanding of multidimensional, multimodal and abstract information; (g) GE can work with students a small part of the wider BIM context, however providing inputs for students to build a solid foundation from which they can develop the necessary skills to work with this modeling; (h) the teaching and learning of BIM will be more solid if they are continued throughout the student's education, starting already after their access to the university and as part of the basic core disciplines.<br>Resumen: El objetivo de este trabajo es contribuir a la adopción de BIM (Building Information Modeling) en los cursos de pregrado en Ingeniería Civil. Para ello, se realiza un análisis del paradigma BIM y en las experiencias nacionales e internacionales de enseñanza y aprendizaje sobre el tema; se identifican las habilidades necesarias para trabajar con BIM y cuáles son los elementos que este modelo puede aportar a la configuración instrumental y cognitiva del estudiante; se presentan métodos y estrategias de enseñanza y aprendizaje que resulten adecuados para trabajar con el contexto de BIM. A partir de los estudios realizados, se ha desarrollado un metodo para identificar las interfaces entre el currículo del Ingeniero Civil y BIM y son mapeados momentos la educación de los estudiantes en el que este modelado puede ser discutido. Finalmente, la investigación se dirige a la Expresión Gráfica y crea una propuesta de estructuración de este sector dentro de un plan de estudios de ingeniería civil para adoptar BIM. El trabajo es exploratorio, de naturaleza fenomenológica y utiliza como supuestos la implicación de la investigadora, el rigor de la investigación cualitativa y el paradigma de la complejidad. Entre los principales resultados, se puede observar que: (a) la adopción del paradigma BIM demanda de actualización en los cursos de ingeniería civil, lo que implica también la formación de los docentes para trabajar con el tema; (b) experiencias exitosas se han realizado tanto en Brasil como en el extranjero y demuestran que no sólo es posible trabajar BIM en la graduación, como él ha traído una serie de ventajas para el aprendizaje de la ingeniería y el desarrollo cognitivo de los estudiantes; (c) es importante crear un plan para la implementación de BIM, teniendo en cuenta el contexto específico de cada institución; (d) un curso que tiene entre sus objetivos tratar de BIM debe promover un alto grado de integración entre las disciplinas y el trabajo colaborativo entre los maestros; (e) para que ocurra un aprendizaje integrado y continuo, BIM debería ser trabajado en diversos componentes del plan de estudios a lo largo del curso; (f) de modo que el área de EG pueda contribuir a la formación del ingeniero civil en BIM, su alcance debe ampliarse, incluyendo no sólo el diseño (2D) y modelado geométrico (3D), pero también abarcando la comprensión de la información multidimensional, multimodal y abstracta; (g) la EG puede proporcionar insumos para que los estudiantes puedan construir una base sólida para desarrollar las habilidades necesarias para trabajar con este modelaje; (h) la enseñanza-aprendizaje de BIM será más sólida si se continúa a lo largo de la educación del estudiante, desde su acceso a la universidad y las disciplinas del núcleo básico.
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Christo, Danilo dos Santos. "Introdução da noção de variável em expressões algébricas por meio da resolução de problemas: Uma abordagem dinâmica." Pontifícia Universidade Católica de São Paulo, 2006. https://tede2.pucsp.br/handle/handle/11080.
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Previous issue date: 2006-10-31<br>Students difficulties in writing and interpreting algebraic language,
particularly in comprehending the meaning of variable have been discussed
by such researchers as Kieran, Küchemann, Arcavi and others.
In this research, we evaluate a teaching proposal in which it is aimed at
explaining established relations between elements of circumstances of
proportionality and generalizable arithmetic expressions. This analysis of
regularity eases the algebraic language teaching through a dynamic
approach in which the notion of dependence among the circumstantial
variables is emphasized. This proposal was applied to a sixth grade group of
a public primary school in São Paulo city. The analysis of the obtained results
allows us to verify the teaching proposal s efficiency for attaining the
objectives of this research and provides tools for training teachers<br>Dificuldades dos alunos na escrita e interpretação da linguagem algébrica e,
em particular, na compreensão do significado de variável, têm sido
discutidas por pesquisadores como Kieran, Küchemann, Arcavi, entre outros.
Nesta pesquisa, avaliamos uma proposta de ensino na qual busca-se
descrever as relações estabelecidas entre os elementos de situações de
proporcionalidade com as expressões aritméticas generalizáveis. A análise
dessas regularidades favorece o ensino da linguagem algébrica, em uma
abordagem dinâmica em que se enfatiza a noção de dependência entre as
variáveis envolvidas na situação. A proposta foi desenvolvida em uma sexta
série do ensino fundamental de uma escola municipal da cidade de São
Paulo. A análise dos resultados obtidos permite-nos constatar a eficiência da
proposta de ensino para a consecução dos objetivos visados nesta
investigação e fornece subsídios para a formação de professores
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Goria, Stéphane. "L'Expression du problème dans la Recherche d'Informations: Application à un contexte d'Intermédiation Territoriale." Phd thesis, Université Nancy II, 2006. http://tel.archives-ouvertes.fr/tel-00011918.
Testo completoAbstract (sommario):
L'Intelligence Territoriale est un concept récemment apparu en France. Nous l'avons identifié comme la conjugaison d'actions d'Intelligence Economique et de Knowledge Management appliquées à un territoire. L'Intermédiation Territoriale en est une forme particulière, qui s'appuie sur la notion de médiation et l'utilisation d'intermédiaire(s) humain(s). Nous avons participé à la mise en place d'un tel dispositif, dans lequel les intermédiaires humains sont notamment chargés de résoudre des problèmes informationnels pour des tiers. Nos travaux ont cherché à améliorer l'efficacité de ces personnels pour répondre aux Problèmes de Recherche d'Informations (PRI) qui leurs sont posés. Dans ce but, nous avons puisé notre inspiration dans les domaines de la Communication Humaine, de la Représentation des Connaissances et de la Résolution de Problèmes. Nous en avons déduit une solution en quatre parties : (1) des Principes de bonne formulation d'un énoncé de PRI, (2) un Modèle d'aide à la génération d'un questionnement sur un PRI, (3) un Outil d'aide à la représentation de l'interprétation d'un sujet de PRI, (4) une Pertinence informationnelle orientée vers la demande.
Libri sul tema "Expression problem"
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Stepney, Stella A. Art therapy with students at risk: Fostering resilience and growth through self-expression. 2nd ed. Springfield, Ill: Charles C. Thomas, 2010.
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Stepney, Stella A. Art therapy with students at risk: Fostering resilience and growth through self-expression. 2nd ed. Springfield, Ill: Charles C. Thomas, 2010.
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Henderson, Ian. Solving the inclusion body problem: A case study : high level expression of TEM-1 [beta]-lactamase in Escherichia coli. [s.l.]: typescript, 1993.
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Roy, Michel. Expressions idiomatiques en français. Vanier, Ont: CFORP, 1998.
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Judi, Lesiak, ed. Problems in written expression: Assessment and remediation. New York, N.Y: Guilford Press, 1989.
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Harer, John B. Censorship of expression in the 1980s: Statistical survey. London: Greenwood, 1994.
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Pekarskai͡a, Irina Vladimirovna. Kontaminat͡sii͡a v kontekste problemy sistemnosti stilisticheskikh resursov russkogo i͡azyka. Abakan: Khakasskiĭ gos. universitet im. N.F. Katanova, 2000.
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Wuthnow, Robert. The God problem: Expressing faith and being reasonable. Berkeley: University of California Press, 2012.
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John, Mason. Expressing generality. Milton Keynes: Centre for Mathematics Education, Open University, 1988.
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Incorporated, Girls. Girls enCourage: A component of Girls Inc. sporting chance, for girls ages 12-14 : outdoor adventure, nontraditional sports, communication and teambuilding, group and individual goal setting, responsible risk taking, creative self-expression, problem solving, leadership skills, expedition planning. New York, NY: Girls Inc., 2007.
Cerca il testo completoCapitoli di libri sul tema "Expression problem"
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Torgersen, Mads. "The Expression Problem Revisited." In ECOOP 2004 – Object-Oriented Programming, 123–46. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-540-24851-4_6.
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Laugier, Sandra. "Understanding, Meaning, and Expression." In Human Understanding as Problem, edited by Jesús Padilla Gálvez and Margit Gaffal, 115–34. Berlin, Boston: De Gruyter, 2018. http://dx.doi.org/10.1515/9783110613384-007.
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Mayr, Ernst W. "The Dynamic Tree Expression Problem." In Concurrent Computations, 157–79. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4684-5511-3_10.
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Ferreira, Cândida. "Gene Expression Programming in Problem Solving." In Soft Computing and Industry, 635–53. London: Springer London, 2002. http://dx.doi.org/10.1007/978-1-4471-0123-9_54.
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Merz, Peter, and Andreas Zell. "Clustering Gene Expression Profiles with Memetic Algorithms." In Parallel Problem Solving from Nature — PPSN VII, 811–20. Berlin, Heidelberg: Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/3-540-45712-7_78.
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Bartoli, Alberto, Simone Cumar, Andrea De Lorenzo, and Eric Medvet. "Compressing Regular Expression Sets for Deep Packet Inspection." In Parallel Problem Solving from Nature – PPSN XIII, 394–403. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-10762-2_39.
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Ferreira, Margarida, Miguel Terra-Neves, Miguel Ventura, Inês Lynce, and Ruben Martins. "FOREST: An Interactive Multi-tree Synthesizer for Regular Expressions." In Tools and Algorithms for the Construction and Analysis of Systems, 152–69. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-72016-2_9.
Testo completoAbstract (sommario):
AbstractForm validators based on regular expressions are often used on digital forms to prevent users from inserting data in the wrong format. However, writing these validators can pose a challenge to some users.We present Forest, a regular expression synthesizer for digital form validations. Forest produces a regular expression that matches the desired pattern for the input values and a set of conditions over capturing groups that ensure the validity of integer values in the input. Our synthesis procedure is based on enumerative search and uses a Satisfiability Modulo Theories (SMT) solver to explore and prune the search space. We propose a novel representation for regular expressions synthesis, multi-tree, which induces patterns in the examples and uses them to split the problem through a divide-and-conquer approach. We also present a new SMT encoding to synthesize capture conditions for a given regular expression. To increase confidence in the synthesized regular expression, we implement user interaction based on distinguishing inputs.We evaluated Forest on real-world form-validation instances using regular expressions. Experimental results show that Forest successfully returns the desired regular expression in 70% of the instances and outperforms Regel, a state-of-the-art regular expression synthesizer.
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Czajkowski, Marcin, Krzysztof Jurczuk, and Marek Kretowski. "Generic Relative Relations in Hierarchical Gene Expression Data Classification." In Parallel Problem Solving from Nature – PPSN XVI, 372–84. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-58115-2_26.
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Chen, Ying-ping, and David E. Goldberg. "Introducing Start Expression Genes to the Linkage Learning Genetic Algorithm." In Parallel Problem Solving from Nature — PPSN VII, 351–60. Berlin, Heidelberg: Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/3-540-45712-7_34.
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Jorro-Aragoneses, Jose L., Belén Díaz-Agudo, and Juan A. Recio-García. "Addressing the Cold-Start Problem in Facial Expression Recognition." In Case-Based Reasoning Research and Development, 197–211. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-24586-7_14.
Testo completoAtti di convegni sul tema "Expression problem"
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Landero-Sepúlveda, Pamela, Sofia Castro-Castro, and Mario Inostroza-Ponta. "Evaluating Alternate Feature Sets as a Local Search Strategy for Gene Expression Feature Selection Problem." In 2024 43rd International Conference of the Chilean Computer Science Society (SCCC), 1–7. IEEE, 2024. https://doi.org/10.1109/sccc63879.2024.10767621.
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Li, Y., F. P. Dawalibi, J. Cheng, and Y. Jiang. "Integrated Corrosion Analysis Software and Its Application to Dc Corrosion Analysis." In CONFERENCE 2023, 1–12. NACE International, 2023. https://doi.org/10.5006/c2023-18819.
Testo completoAbstract (sommario):
Abstract This paper introduces a novel approach to analyze corrosion effects and to model electrochemical problems with non-linear boundary conditions. The computation of the electrical current distribution along protected structures is based on an automated algorithm involving the polarization curves and an integrated iterative process. The method is first used to solve a well-known benchmark test problem and the results are compared to those obtained using the benchmark analytical expression. Then, an example of a realistic cathodic protection system aimed at mitigating stray currents from a HVDC electrode on a pipeline is described and discussed. It is shown that the proposed iterative approach accurately computes the electrochemical potential process. This approach constitutes the core effort in the development of an accurate non-linear polarization solver.
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Wang, Yanlin, and Bruno C. d. S. Oliveira. "The expression problem, trivially!" In Modularity '16: 15th International Conference on Modularity. New York, NY, USA: ACM, 2016. http://dx.doi.org/10.1145/2889443.2889448.
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Black, Andrew P. "The Expression Problem, Gracefully." In ECOOP '15: European Conference on Object-Oriented Programming ECOOP 2015. New York, NY, USA: ACM, 2015. http://dx.doi.org/10.1145/2786555.2786556.
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Valizadeh, Mojtaba, Philip John Gorinski, Ignacio Iacobacci, and Martin Berger. "Correct and Optimal: The Regular Expression Inference Challenge." In Thirty-Third International Joint Conference on Artificial Intelligence {IJCAI-24}. California: International Joint Conferences on Artificial Intelligence Organization, 2024. http://dx.doi.org/10.24963/ijcai.2024/717.
Testo completoAbstract (sommario):
We propose regular expression inference (REI) as a challenge for code/language modelling, and the wider machine learning community. REI is a supervised machine learning (ML) and program optimisation task, and poses the problem of finding minimal regular expressions from examples: Given two finite sets of strings P and N and a cost function cost(·), the task is to generate an expression r that accepts all strings in P and rejects all strings in N , while no other such expression r′ exists with cost(r′) < cost(r). REI has advantages as a challenge problem: (i) regular expressions are well-known, widely used, and a natural idealisation of code; (ii) REI’s asymptotic worst-case complexity is well understood; (iii) REI has a small number of easy to understand parameters (e.g. P or N cardinality, string lengths of examples, or the cost function); this lets us easily finetune REI-hardness; (iv) REI, with its emphasis on optimisation, is an unsolved problem for deep learning based ML. Recently, an REI solver was implemented on GPUs, using program synthesis techniques. This enabled, for the first time, fast generation of minimal regular expressions for complex REI instances. Building on this advance, we generate and publish the first large-scale datasets for REI, and devise and evaluate several initial heuristic and machine learning baselines. We invite the community to participate and explore ML methods that learn to solve REI problems. We believe that progress in REI directly translates to progress in code/language modelling.
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Jamkhedkar, Pramod A., Gregory L. Heileman, and Iván Martínez-Ortiz. "The problem with rights expression languages." In the ACM workshop. New York, New York, USA: ACM Press, 2006. http://dx.doi.org/10.1145/1179509.1179522.
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Cai, Liang-Wu. "Using MATLAB to Enhance Engineering Students’ Analytical Problem-Solving Skills." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-43020.
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Symbolic analysis is one of the most feared tasks for many undergraduate students in engineering disciplines. Students argue that, without numerical values, it is difficult to make a sense out of a long expression. Instructors have experienced that students are diffident in such analyses; and they quickly lose interest in the topic. This trend has been enhanced with more prevalent use of computers in engineering curricula in recent years. In the senior level Mechanical Vibrations course, this author has experimented with an innovative procedure of using mathematical software such as MATLAB to enhance the students’ learning experience with extensive symbolic calculations. In this experiment, MATLAB is used as a rudimentary plotting device that allows students to plot curves. The procedure provides students a systematical approach to produce parametric plots from an analytical expression, and to validate the expression on physical grounds. This innovative procedure has changed students’ perception about long expressions, decreased their fear, and boosted their confidence in their analytical skills. All these help student to develop a more positive altitude towards symbolic analyses.
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Wang, Desheng, Yubo Qian, Yu Xing, Yansong Li, Yifei Yang, Qing Wu, and Tieke He. "Problem Kit System for Expression Ability Evaluation." In 2020 7th International Conference on Dependable Systems and Their Applications (DSA). IEEE, 2020. http://dx.doi.org/10.1109/dsa51864.2020.00067.
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Carvalho Junior, Francisco Heron de. "The expression problem in platform-aware programming." In Simpósio Brasileiro de Linguagens de Programação, 94–97. Sociedade Brasileira de Computação, 2024. http://dx.doi.org/10.5753/sblp.2024.3689.
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Platform-aware programming involves making assumptions about specific features of the target execution environment to improve performance. We restate a fundamental problem in software extensibility called The Expression Problem for platform-aware programming to show how a solution based on dynamic multiple dispatch over platform types may improve such a performance engineering practice.
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Awal, Ahmad-Montaser, Harold Mouchere, and Christian Viard-Gaudin. "The Problem of Handwritten Mathematical Expression Recognition Evaluation." In 2010 International Conference on Frontiers in Handwriting Recognition (ICFHR). IEEE, 2010. http://dx.doi.org/10.1109/icfhr.2010.106.
Testo completoRapporti di organizzazioni sul tema "Expression problem"
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Mayr, Ernst W. The Dynamic Tree Expression Problem,. Fort Belvoir, VA: Defense Technical Information Center, May 1987. http://dx.doi.org/10.21236/ada323937.
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Chejanovsky, Nor, and Bruce D. Hammock. Enhancement of Baculoviruses' Insecticidal Potency by Expression of Synergistic Anti-Insect Scorpion Toxins. United States Department of Agriculture, January 1996. http://dx.doi.org/10.32747/1996.7573070.bard.
Testo completoAbstract (sommario):
The extensive use or non-specific, hazardous, chemical insecticides demands the development of "healthier" alternative means for pest control. Insect-specific, baculoviruses expressing anti-insect toxin genes (from mites or scorpions) demonstrated in laboratory assays and field trials enhanced insecticidal activity and provided some protection from lepidopterous larvae to agricultural plantations. To utilize recombinant baculoviruses as commercial biopesticides in row crop agriculture, further increase in their speed of kill should be achieved and the reduction in crop damage should be comparable to the levels obtained with organic insecticides (the problem). In this project we developed strategies to improve further the efficacy of recombinant baculoviruses which included: I) Synergism among baculoviruses expressing different anti-insect toxins: a) Synergism among two complementary anti-insect scorpion neurotoxins each expressed by a separate recombinant baculovirus, both regulated by the same or a different viral promoter. b) Synergism among two complementary anti-insect scorpion neurotoxins expressed by the same recombinant virus, both regulated by the same or a different viral promoter respectively. The above included two classes of pharmacologically complementary toxins: i) toxins with strictly anti-insect selectivity (excitatory and depressant); ii) toxins with preferential anti-insect activity (anti-insect alpha toxins). c) Synergism among wild type viruses, recombinant baculoviruses and chemicals (insecticides and phytochemicals) II) Identification of more potent toxins against lepidopterous pests for their expression by baculoviruses. Our approach was based on the synergistic effect displayed by the combined application of pairs of anti-insect toxins to blowfly and lepidopterous larvae that resulted in 5 fold increase in their insecticidal activity without apparent increase in their anti-mammal toxicity (toxins LqhIT2 and LqhaIT, LqhIT2 and AaIT, and LqhaIT and AaIT (1). Thus, we developed new concepts and produced a "second generation" of recombinant baculoviruses with enhanced potencies and speeds of kill comparable to classical insecticides. These achievements contribute to make these biopesticides a viable alternative to minimize the use of hazardous chemicals in pest control. Also, our project contributed new tools and model systems to advance the study of insect sodium channels.
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Pichersky, Eran, Alexander Vainstein, and Natalia Dudareva. Scent biosynthesis in petunia flowers under normal and adverse environmental conditions. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7699859.bard.
Testo completoAbstract (sommario):
The ability of flowering plants to prosper throughout evolution, and for many crop plants to set fruit, is strongly dependent on their ability to attract pollinators. To that end many plants synthesize a spectrum of volatile compounds in their flowers. Scent is a highly dynamic trait that is strongly influenced by the environment. However, with high temperature conditions becoming more common, the molecular interplay between this type of stress and scent biosynthesis need to be investigated. Using petunia as a model system, our project had three objectives: (1) Determine the expression patterns of genes encoding biosynthetic scent genes (BSGs) and of several genes previously identified as encoding transcription factors involved in scent regulation under normal and elevated temperature conditions. (2) Examine the function of petunia transcription factors and a heterologous transcription factor, PAPl, in regulating genes of the phenylpropanoid/benzenoid scent pathway. (3) Study the mechanism of transcriptional regulation by several petunia transcription factors and PAPl of scent genes under normal and elevated temperature conditions by examining the interactions between these transcription factors and the promoters of target genes. Our work accomplished the first two goals but was unable to complete the third goal because of lack of time and resources. Our general finding was that when plants grew at higher temperatures (28C day/22C night, vs. 22C/16C), their scent emission decreased in general, with the exception of a few volatiles such as vanillin. To understand why, we looked at gene transcription levels, and saw that generally there was a good correlation between levels of transcriptions of gene specifying enzymes for specific scent compounds and levels of emission of the corresponding scent compounds. Enzyme activity levels, however, showed little difference between plants growing at different temperature regimes. Plants expressing the heterologous gene PAPl showed general increase in scent emission in control temperature conditions but emission decreased at the higher temperature conditions, as seen for control plants. Finally, expression of several transcription factor genes decreased at high temperature, but expression of new transcription factor, EOB-V, increased, implicating it in the decrease of transcription of BSGs. The major conclusion of this work is that high temperature conditions negatively affect scent emission from plants, but that some genetic engineering approaches could ameliorate this problem.
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Ohad, Nir, and Robert Fischer. Control of Fertilization-Independent Development by the FIE1 Gene. United States Department of Agriculture, August 2000. http://dx.doi.org/10.32747/2000.7575290.bard.
Testo completoAbstract (sommario):
A fundamental problem in biology is to understand how fertilization initiates reproductive development. During plant reproduction, one sperm cell fuses with the egg to form an embryo, whereas a second sperm cell fuses with the adjacent central cell nucleus to form the endosperm tissue that supports embryo and/or seedling development. To understand the mechanisms that initiate reproduction, we have isolated mutants of Arabidopsis that allow for replication of the central cell and subsequent endosperm development without fertilization. In this project we have cloned the MEA gene and showed that it encode a SET- domain polycomb protein. Such proteins are known to form chromatin-protein complexes that repress homeotic gene transcription and influence cell proliferation from Drosophylla to mammals. We propose a model whereby MEA and an additional polycomb protein we have cloned, FIE , function to suppress a critical aspect of early plant reproduction and endosperm development, until fertilization occurs. Using a molecular approach we were able to determine that FIE and MEA interact physically, suggesting that these proteins have been conserved also during the evolution of flowering plants. The analysis of MEA expression pattern revealed that it is an imprinted gene that displays parent-of- origin-dependent monoallelic expression specifically in the endosperm tissue. Silencing of the paternal MEA allele in the endosperm and the phenotype of mutant mea seeds support the parental conflict theory for the evolution of imprinting in plants and mammals. These results contribute new information on the initiation of endosperm development and provide a unique entry point to study asexual reproduction and apomixis which is expected to improve crop production.
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Heifetz, Yael, and Michael Bender. Success and failure in insect fertilization and reproduction - the role of the female accessory glands. United States Department of Agriculture, December 2006. http://dx.doi.org/10.32747/2006.7695586.bard.
Testo completoAbstract (sommario):
The research problem. Understanding of insect reproduction has been critical to the design of insect pest control strategies including disruptions of mate-finding, courtship and sperm transfer by male insects. It is well known that males transfer proteins to females during mating that profoundly affect female reproductive physiology, but little is known about the molecular basis of female mating response and no attempts have yet been made to interfere with female post-mating responses that directly bear on the efficacy of fertilization. The female reproductive tract provides a crucial environment for the events of fertilization yet thus far those events and the role of the female tract in influencing them are poorly understood. For this project, we have chosen to focus on the lower reproductive tract because it is the site of two processes critical to reproduction: sperm management (storage, maintenance, and release from storage) and fertilization. E,fforts during this project period centered on the elucidation of mating responses in the female lower reproductive tract The central goals of this project were: 1. To identify mating-responsive genes in the female lower reproductive tract using DNA microarray technology. 2. In parallel, to identify mating-responsive genes in these tissues using proteomic assays (2D gels and LC-MS/MS techniques). 3. To integrate proteomic and genomic analyses of reproductive tract gene expression to identify significant genes for functional analysis. Our main achievements were: 1. Identification of mating-responsive genes in the female lower reproductive tract. We identified 539 mating-responsive genes using genomic and proteomic approaches. This analysis revealed a shift from gene silencing to gene activation soon after mating and a peak in differential gene expression at 6 hours post-mating. In addition, comparison of the two datasets revealed an expression pattern consistent with the model that important reproductive proteins are pre-programmed for synthesis prior to mating. This work was published in Mack et al. (2006). Validation experiments using real-time PCR techniques suggest that microarray assays provide a conservativestimate of the true transcriptional activity in reproductive tissues. 2.lntegration of proteomics and genomics data sets. We compared the expression profiles from DNA microarray data with the proteins identified in our proteomic experiments. Although comparing the two data sets poses analyical challenges, it provides a more complete view of gene expression as well as insights into how specific genes may be regulated. This work was published in Mack et al. (2006). 3. Development of primary reproductive tract cell cultures. We developed primary cell cultures of dispersed reproductive tract cell types and determined conditions for organ culture of the entire reproductive tract. This work will allow us to rapidly screen mating-responsive genes for a variety of reproductive-tract specifi c functions. Scientific and agricultural significance. Together, these studies have defined the genetic response to mating in a part of the female reproductive tract that is critical for successful fertllization and have identified alarge set of mating-responsive genes. This work is the first to combine both genomic and proteomic approaches in determining female mating response in these tissues and has provided important insights into insect reproductive behavior.
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Leach, Roland M., Mark Pines, Carol V. Gay, and Shmuel Hurwitz. In vivo and in vitro Chondrocyte Metabolism in Relationship to the Developemnt of Tibial Dyschondroplasia in Broiler Chickens. United States Department of Agriculture, July 1993. http://dx.doi.org/10.32747/1993.7568090.bard.
Testo completoAbstract (sommario):
Skeletal deformities are a significant financial and welfare problem for the world poultry industry. Tibial dyschondroplasia (TD) is the most prevalent skeletal abnormality found in young broilers, turkeys and ducks. Tibial dyschondroplasia results from a perturbation of the sequence of events in the epiphyseal growth plate, the tissue responsible for longitudinal bone growth. The purpose of this investigation was to test the hypothesis that TD was the result of a failure of growth plate chondrocytes to differentiate and express the chemotactic molecules required for cartilage vascularization. In this investigation in situ hybridization and immunocytochemical techniques were used to study chondrocyte gene products associated with cartilage maturation and vascularization such as osteopontin, osteonectin, type X collagen, and alkaline phosphatase. All markers were present in the growth plate tissue anter or to the TD lesion but were greatly diminished in the TD lesion. Thus, rather than not acquiring the markers for hypertrophy, it appears that the growth plate chondrocytes reach a certain stage of hypertrophy and then de-differentiate into cells which resemble chondrocytes in the prehypertrophic zone. Similar patterns were observed in all TD tissues examined whether the lesions were spontaneous or induced by dietary treatments or genetic selection. The decrease in gene expression can at least be partially explained by the fact that many of the dysplastic chondrocytes show classic signs of apoptosis. These results provide an explanation for the observation that a variety of genes show reduced expression in the TD lesion when examined by in situ hybridization. This would suggest that future research should focus on the earliest detectable stages in the development of TD and examine endocrine and autocrine factors which cause chondrocytes to de-differentiate and undergo premature apoptosis.
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Sessa, Guido, and Gregory Martin. Role of GRAS Transcription Factors in Tomato Disease Resistance and Basal Defense. United States Department of Agriculture, 2005. http://dx.doi.org/10.32747/2005.7696520.bard.
Testo completoAbstract (sommario):
The research problem: Bacterial spot and bacterial speck diseases of tomato are causedby strains of Xanthomonas campestris pv. vesicatoria (Xcv) and Pseudomonas syringae pv.tomato (Pst), respectively. These bacteria colonize aerial parts of the plant and causesignificant losses in tomato production worldwide. Protection against Xcv and Pst bycultural practices or chemical control has been unsuccessful and there are only limitedsources of genetic resistance to these pathogens. In previous research supported in part byBARD IS-3237-01, we extensively characterized changes in tomato gene expression uponthe onset of spot and speck disease resistance. A remarkable finding of these studies wasthe inducibility in tomato leaves by both Xcv and Pst strains of genes encodingtranscriptional activator of the GRAS family, which has not been previously linked todisease resistance. Goals: Central goals of this research were to investigate the role of GRAS genes in tomatoinnate immunity and to assess their potential use for disease control.Specific objectives were to: 1. Identify GRAS genes that are induced in tomato during thedefense response and analyze their role in disease resistance by loss-of-function experiments.2. Overexpress GRAS genes in tomato and characterize plants for possible broad-spectrumresistance. 3. Identify genes whose transcription is regulated by GRAS family. Our main achievements during this research program are in three major areas:1. Identification of tomato GRAS family members induced in defense responses andanalysis of their role in disease resistance. Genes encoding tomato GRAS family memberswere retrieved from databases and analyzed for their inducibility by Pst avirulent bacteria.Real-time RT-PCR analysis revealed that six SlGRAS transcripts are induced during theonset of disease resistance to Pst. Further expression analysis of two selected GRAS genesshowed that they accumulate in tomato plants in response to different avirulent bacteria orto the fungal elicitor EIX. In addition, eight SlGRAS genes, including the Pst-induciblefamily members, were induced by mechanical stress in part in a jasmonic acid-dependentmanner. Remarkably, SlGRAS6 gene was found to be required for tomato resistance to Pstin virus-induced gene silencing (VIGS) experiments.2. Molecular analysis of pathogen-induced GRAS transcriptional activators. In aheterologous yeast system, Pst-inducible GRAS genes were shown to have the ability toactivate transcription in agreement with their putative function of transcription factors. Inaddition, deletion analysis demonstrated that short sequences at the amino-terminus ofSlGRAS2, SlGRAS4 and SlGRAS6 are sufficient for transcriptional activation. Finally,defense-related SlGRAS proteins were found to localize to the cell nucleus. 3. Disease resistance and expression profiles of transgenic plants overexpressing SlGRASgenes. Transgenic plants overexpressing SlGRAS3 or SlGRAS6 were generated. Diseasesusceptibility tests revealed that these plants are not more resistant to Pst than wild-typeplants. Gene expression profiles of the overexpressing plants identified putative direct orindirect target genes regulated by SlGRAS3 and SlGRAS6. Scientific and agricultural significance: Our research activities established a novel linkbetween the GRAS family of transcription factors, plant disease resistance and mechanicalstress response. SlGRAS6 was found to be required for disease resistance to Pstsuggesting that this and possibly other GRAS family members are involved in thetranscriptional reprogramming that takes place during the onset of disease resistance.Their nuclear localization and transcriptional activation ability support their proposed roleas transcription factors or co-activators. However, the potential of utilizing GRAS familymembers for the improvement of plant disease resistance in agriculture has yet to bedemonstrated.
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Crisosto, Carlos, Susan Lurie, Haya Friedman, Ebenezer Ogundiwin, Cameron Peace, and George Manganaris. Biological Systems Approach to Developing Mealiness-free Peach and Nectarine Fruit. United States Department of Agriculture, 2007. http://dx.doi.org/10.32747/2007.7592650.bard.
Testo completoAbstract (sommario):
Peach and nectarine production worldwide is increasing; however consumption is flat or declining because of the inconsistent eating quality experienced by consumers. The main factor for this inconsistent quality is mealiness or woolliness, a form of chilling injury that develops following shipping periods in the global fruit market today. Our research groups have devised various postharvest methods to prolong storage life, including controlled atmosphere and delayed storage; however, these treatments only delay mealiness. Mealiness texture results from disruption of the normal ripening process involving disassembly of cell wall material, and creates a soft fruit texture that is dry and grainy instead of juicy and smooth. Solving this problem is a prerequisite for increasing the demand for fresh peach and nectarine. Two approaches were used to reveal genes and their associated biochemical processes that can confer resistance to mealiness or wooliness. At the Volcani Center, Israel, a nectarine cultivar and the peach cultivar (isogenetic materials) from which the nectarine cultivar spontaneously arose, and at the Kearney Agricultural Center of UC Davis, USA, a peach population that segregates for quantitative resistance to mealiness was used for dissecting the genetic components of mealiness development. During our project we have conducted research integrating the information from phenotypic, biochemical and gene expression studies, proposed possible candidate genes and SNPs-QTLs mapping that are involved in reducing peach mealiness susceptibility. Numerous genes related to ethylene biosynthesis and its signal transduction, cell wall structure and metabolism, stress response, different transcription factor families were detected as being differentially accumulated in the cold-treated samples of these sensitive and less sensitive genotypes. The ability to produce ethylene and keep active genes involved in ethylene signaling, GTP-binding protein, EIN-3 binding protein and an ethylene receptor and activation of ethyleneresponsive fruit ripening genes during cold storage provided greater resistance to CI. Interestingly, in the functional category of genes differentially expressed at harvest, less chilling sensitive cultivar had more genes in categories related to antioxidant and heat sock proteins/chaperones that may help fruit to adapt to low temperature stress. The specific objectives of the proposed research were to: characterize the phenotypes and cell wall components of the two resistant systems in response to mealiness- inducing conditions; identify commonalities and specific differences in cell wall proteins and the transcriptome that are associated with low mealiness incidence; integrate the information from phenotypic, biochemical, and gene expression studies to identify candidate genes that are involved in reducing mealiness susceptibility; locate these genes in the Prunus genome; and associate the genes with genomic regions conferring quantitative genetic variation for mealiness resistance. By doing this we will locate genetic markers for mealiness development, essential tools for selection of mealiness resistant peach lines with improved fruit storability and quality. In our research, QTLs have been located in our peach SNPs map, and proposed candidate genes obtained from the integrated result of phenotypic, biochemical and gene expression analysis are being identified in our QTLs as an approach searching for consistent assistant markers for peach breeding programs.
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Friedman, Haya, Chris Watkins, Susan Lurie, and Susheng Gan. Dark-induced Reactive Oxygen Species Accumulation and Inhibition by Gibberellins: Towards Inhibition of Postharvest Senescence. United States Department of Agriculture, December 2009. http://dx.doi.org/10.32747/2009.7613883.bard.
Testo completoAbstract (sommario):
Dark-induced senescence could pose a major problem in export of various crops including cuttings. The assumption of this work was that ROS which is increased at a specific organelle can serve as a signal for activation of cell senescence program. Hormones which reduce senescence in several crops like gibberellic acid (GA) and possibly cytokinin (CK) may reduce senescence by inhibiting this signal. In this study we worked on Pelargonium cuttings as well as Arabidopsis rosette. In Pelargonium the increase in ROS occurred concomitantly with increase in two SAGs, and the increase persisted in isolated chloroplasts. In Arabidopsis we used two recentlydeveloped technologies to examine these hypotheses; one is a transcriptome approach which, on one hand, enabled to monitor expression of genes within the antioxidants network, and on the other hand, determine organelle-specific ROS-related transcriptome footprint. This last approach was further developed to an assay (so called ROSmeter) for determination of the ROS-footprint resulting from defined ROS stresses. The second approach involved the monitoring of changes in the redox poise in different organelles by measuring fluorescence ratio of redox-sensitive GFP (roGFP) directed to plastids, mitochondria, peroxisome and cytoplasm. By using the roGFP we determined that the mitochondria environment is oxidized as early as the first day under darkness, and this is followed by oxidation of the peroxisome on the second day and the cytoplast on the third day. The plastids became less oxidized at the first day of darkness and this was followed by a gradual increase in oxidation. The results with the ROS-related transcriptome footprint showed early changes in ROS-related transcriptome footprint emanating from mitochondria and peroxisomes. Taken together these results suggest that the first ROS-related change occurred in mitochondria and peroxisomes. The analysis of antioxidative gene’s network did not yield any clear results about the changes occurring in antioxidative status during extended darkness. Nevertheless, there is a reduction in expression of many of the plastids antioxidative related genes. This may explain a later increase in the oxidation poise of the plastids, occurring concomitantly with increase in cell death. Gibberellic acid (GA) prevented senescence in Pelargonium leaves; however, in Arabidopsis it did not prevent chlorophyll degradation, but prevented upregulation of SAGs (Apendix Fig. 1). Gibberellic acid prevented in Pelargonium the increase in ROS in chloroplast, and we suggested that this prevents the destruction of the chloroplasts and hence, the tissue remains green. In Arabidopsis, reduction in endogenous GA and BA are probably not causing dark-induced senescence, nevertheless, these materials have some effect at preventing senescence. Neither GA nor CK had any effect on transcriptome footprint related to ROS in the various organelles, however while GA reduced expression of few general ROS-related genes, BA mainly prevented the decrease in chloroplasts genes. Taken together, GA and BA act by different pathways to inhibit senescence and GA might act via ROS reduction. Therefore, application of both hormones may act synergistically to prevent darkinduced senescence of various crops.
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Tucker, Mark L., Shimon Meir, Amnon Lers, Sonia Philosoph-Hadas, and Cai-Zhong Jiang. Elucidation of signaling pathways that regulate ethylene-induced leaf and flower abscission of agriculturally important plants. United States Department of Agriculture, January 2012. http://dx.doi.org/10.32747/2012.7597929.bard.
Testo completoAbstract (sommario):
The Problem: Abscission is a highly regulated process, occurring as a natural terminal stage of development, in which various organs are separated from the parent plant. In most plant species, the process is initiated by a decrease in active auxin in the abscission zone (AZ) and an increase in ethylene, and may be accelerated by postharvest or environmental stresses. Another potential key regulator in abscission is IDA (Inflorescence Deficient in Abscission), which was identified as an essential peptide signal for floral organ abscission in Arabidopsis. However, information is still lacking regarding the molecular mechanisms integrating all these regulators. In our previous BARD funded research we made substantial progress towards understanding these molecular events in tomato, and the study is still in progress. We established a powerful platform for analysis of genes for regulatory proteins expressed in AZ. We identified changes in gene expression for several transcription factors (TFs) directly linked to ethylene and auxin signaling and several additional regulatory proteins not so obviously linked to these hormones. Moreover, we demonstrated using a virus-induced gene silencing (VIGS) assay that several play a functional role in the onset of abscission. Based on these results we have selected 14 genes for further analysis in stably transformed tomato plants. All 14 genes were suppressed by RNA interference (RNAi) using a constitutive promoter, and 5 of them were also suppressed using an abscission-specific promoter. Transformations are currently at different stages of progress including some lines that already display an abscission phenotype. Objectives: We propose here to (1) complete the functional analysis of the stably transformed tomato plants with T2 lines and perform transcriptome analysis using custom abscission-specific microarrays; (2) conduct an indepth analysis of the role of IDA signaling in tomato leaf and flower abscission; (3) perform transcriptome and proteome analyses to extend the earlier gene expression studies to identify transcripts and proteins that are highly specific to the separation layer (i.e., target cells for cell separation) prior to the onset of abscission; (4) extend and compliment the work in tomato using a winnowed set of genes in soybean. Methodology: Next Generation Sequencing (NGS) of mRNA will be used to further increase the list of abscission-associated genes, and for preparation of a custom tomato abscission microarray to test altered gene expression in transgenic plants. Tandem mass spectrometry (LC-MS/MS) of protein extracts from leaf petiole, flower pedicel and their AZ tissues will be used to identify the proteome of the AZ before and during abscission. AZ-specific gene promoters will be used in stably transformed tomato plants to reduce non-target phenotypes. The bean pod mottle virus (BPMV) plasmid vectors will be used for VIGS analysis in soybean. Expected Contribution: Our study will provide new insights into the regulation of ethylene-induced abscission by further revealing the role of key regulators in the process. This will permit development of novel techniques for manipulating leaf and flower abscission, thereby improving the postharvest performance of agriculturally important crops.